This prospective longitudinal survey compared the stress levels of students taught using an outdoor curriculum in a forest, with children in a normal school setting. We were especially interested in the effect outdoor teaching might have on the children’s normal diurnal cortisol rhythm. 48 children (mean age = 11.23; standard deviation (SD) = 0.46) were enrolled, with 37 in the intervention group (IG), and 11 in the control group (CG). The intervention consisted of one full school day per week in the forest over the school year. Stress levels were measured in cortisol with three samples of saliva per day. Furthermore, the data allowed for statistical control of physical activity (PA) values. For data analysis, we used a linear mixed-effects model (LMM) with random intercept and general correlation matrix for the within-unit residuals. The LMM yields that IG have expected greater decline of cortisol compared to CG; rate 0.069 µg/L vs. 0.0102 µg/L (log-units/2 h), p = 0.009. PA does not show a statistically significant interaction with cortisol (p = 0.857), despite being higher in the intervention group (p < 0.001). The main effect in our measures was that the IG had a steady decline of cortisol during the school day. This is in accordance with a healthy child’s diurnal rhythm, with a significant decline of cortisol from morning to noon. This effect is constant over the school year. The CG does not show this decline during either measurement day. Further research is needed to fully explain this interesting phenomenon.
http://ift.tt/2oUCViQ
Κυριακή 30 Απριλίου 2017
Σάββατο 29 Απριλίου 2017
Female white-collar workers remain at higher risk of breast cancer after adjustments for individual risk factors related to reproduction and lifestyle
Objectives
http://ift.tt/2psD9zC
The aim was to investigate the variation in risk of breast cancer between occupational groups with a focus on white-collar and blue-collar workers and to investigate to what extent the differences were explained by risk factors related to reproduction and lifestyle.
MethodsBetween 1991 and 1996, 14 119 women born between 1923 and 1950 and residents of Malmö, Sweden, were included in this cohort study. Individual data on risk factors (eg, age, parity, age at first child, months of breast feeding per child, hormonal replacement therapy, physical activity, alcohol consumption, smoking, height and body mass index) and occupational history were assessed using a questionnaire. First-time diagnoses of invasive breast cancer were identified through the Swedish Cancer Registry up until 31 December 2013.
ResultsA total of 897 women were diagnosed with breast cancer. Analyses adjusted for age showed an increased risk for white-collar workers compared with blue-collar workers and indicated higher risks in the occupational categories: professionals, administrative and bookkeeping than among women in sales, transportation, production and service work. This difference was only marginally attenuated after adjustment for an extensive set of risk factors related to reproduction and lifestyle.
ConclusionReproductive and lifestyle factors explain only a minor part of the increased risk of breast cancer in white-collar workers. Further studies are needed to investigate the remaining factors for the difference in risk between occupational groups.
http://ift.tt/2psD9zC
Study of the critical velocity in tunnels with longitudinal ventilation and spray systems
Publication date: June 2017
Source:Fire Safety Journal, Volume 90
Author(s): Z. Tang, Y.J. Liu, J.P. Yuan, Z. Fang
Based on the Froude similarity law, a small-scale tunnel model (1/14) was built based in this study to investigate critical velocities of tunnels. Critical velocity is the minimum air velocity required to resist the spread of smoke from a fire upstream in a tunnel. A set of experiments was conducted to investigate the critical velocities under different experimental conditions by varying the heat release rate of the fire, ambient temperature, operating pressure and arrangement of the nozzles. The results of the tests with no spray indicated that the ambient temperature has little impact on the critical velocity. Moreover, based on the dimensionless analysis method, a new correlation was established to predict the critical velocities in the tunnel without Water spray-based Fixed Fire Fighting Systems (WFFFS). The accuracy of the correlation was illustrated by the results of the present tests and a number of tests on different scales published by other scholars. Furthermore, 60 tests with WFFFS activation were carried out. The results show that the critical velocity is significantly reduced after the water spray discharged from the nozzles. The maximum reduction of the critical velocity is approximately 31%. The reduction of the critical velocity strongly depends on the number, positions and operating pressures of the nozzles. The mechanisms of the reduction of the critical velocity caused by spraying were discussed. The cooling effect of the water droplets on hot gas is not the only mechanism for decreasing the critical velocity caused by spraying. Spraying increases the inertial force of the longitudinal airflow and is the other mechanism for the reduction.
http://ift.tt/2pg1WIv
Source:Fire Safety Journal, Volume 90
Author(s): Z. Tang, Y.J. Liu, J.P. Yuan, Z. Fang
Based on the Froude similarity law, a small-scale tunnel model (1/14) was built based in this study to investigate critical velocities of tunnels. Critical velocity is the minimum air velocity required to resist the spread of smoke from a fire upstream in a tunnel. A set of experiments was conducted to investigate the critical velocities under different experimental conditions by varying the heat release rate of the fire, ambient temperature, operating pressure and arrangement of the nozzles. The results of the tests with no spray indicated that the ambient temperature has little impact on the critical velocity. Moreover, based on the dimensionless analysis method, a new correlation was established to predict the critical velocities in the tunnel without Water spray-based Fixed Fire Fighting Systems (WFFFS). The accuracy of the correlation was illustrated by the results of the present tests and a number of tests on different scales published by other scholars. Furthermore, 60 tests with WFFFS activation were carried out. The results show that the critical velocity is significantly reduced after the water spray discharged from the nozzles. The maximum reduction of the critical velocity is approximately 31%. The reduction of the critical velocity strongly depends on the number, positions and operating pressures of the nozzles. The mechanisms of the reduction of the critical velocity caused by spraying were discussed. The cooling effect of the water droplets on hot gas is not the only mechanism for decreasing the critical velocity caused by spraying. Spraying increases the inertial force of the longitudinal airflow and is the other mechanism for the reduction.
http://ift.tt/2pg1WIv
Structural response of a steel-frame building to horizontal and vertical travelling fires in multiple floors
Publication date: Available online 28 April 2017
Source:Fire Safety Journal
Author(s): Egle Rackauskaite, Panagiotis Kotsovinos, Guillermo Rein
During previous fire events such as the World Trade Centre Towers (WTC) 1, 2 & 7 in New York (2001), the Windsor Tower in Madrid (2005), and the Plasco building in Iran (2017), flames were observed to travel horizontally across the floor plate and vertically to different floors. Such fires are not considered as part of the traditional prescriptive structural design for fire. Recently, the Travelling Fires Methodology (TFM) has been developed to account for such horizontally travelling nature of fires. A dozen of studies have investigated the structural response of steel, concrete, and composite structures to a single-floor travelling fire. 5 out of 6 of the vertically travelling fire studies have been limited to the structures with a long span composite truss system as in the WTC Towers. The aim of this work is to investigate the response of a substantially different structural system, i.e. a generic multi-storey steel frame, subjected to travelling fires in multiple floors, and varying the number of fire floors, including horizontal and vertical fire spread. A two-dimensional 10-storey 5-bay steel frame is modelled in the finite element software LS-DYNA. The number of multiple fire floors is varied between 1 and 10, and for each of these scenarios, 5 different fire types are investigated. They include four travelling fire scenarios and the standard fire. In total, 51 fire simulations are considered. The development of deflections, axial forces, bending moments and frame utilization are analysed. Results show that the largest stresses develop in the fire floors adjacent to cool floors, and their behaviour is independent of the number of fire floors. Results indicate that both the fire type and the number of fire floors have a significant effect on the failure time (i.e. exceeded element load carrying capacity) and the type of collapse mechanism. In the cases with a low number of fire floors (1–3) failure is dominated by the loss of material strength, while in the cases with larger number of fire floors (5–10) failure is dominated by thermal expansion. Collapse is mainly initiated by the pull-in of external columns (1–3-floor fires; 1–9-floor fires for 2.5% TFM) or swaying of the frame to the side of fire origin (5–10-floor fires). This study has assessed a different structural form compared to previous literature under an extensive range of multiple floor travelling fire scenarios. We find that although vertically travelling fires result in larger beam axial forces and initial deflections, simultaneous travelling fires result in shorter failure times and represent a more onerous scenario for the steel frame investigated.
http://ift.tt/2oVmGTs
Source:Fire Safety Journal
Author(s): Egle Rackauskaite, Panagiotis Kotsovinos, Guillermo Rein
During previous fire events such as the World Trade Centre Towers (WTC) 1, 2 & 7 in New York (2001), the Windsor Tower in Madrid (2005), and the Plasco building in Iran (2017), flames were observed to travel horizontally across the floor plate and vertically to different floors. Such fires are not considered as part of the traditional prescriptive structural design for fire. Recently, the Travelling Fires Methodology (TFM) has been developed to account for such horizontally travelling nature of fires. A dozen of studies have investigated the structural response of steel, concrete, and composite structures to a single-floor travelling fire. 5 out of 6 of the vertically travelling fire studies have been limited to the structures with a long span composite truss system as in the WTC Towers. The aim of this work is to investigate the response of a substantially different structural system, i.e. a generic multi-storey steel frame, subjected to travelling fires in multiple floors, and varying the number of fire floors, including horizontal and vertical fire spread. A two-dimensional 10-storey 5-bay steel frame is modelled in the finite element software LS-DYNA. The number of multiple fire floors is varied between 1 and 10, and for each of these scenarios, 5 different fire types are investigated. They include four travelling fire scenarios and the standard fire. In total, 51 fire simulations are considered. The development of deflections, axial forces, bending moments and frame utilization are analysed. Results show that the largest stresses develop in the fire floors adjacent to cool floors, and their behaviour is independent of the number of fire floors. Results indicate that both the fire type and the number of fire floors have a significant effect on the failure time (i.e. exceeded element load carrying capacity) and the type of collapse mechanism. In the cases with a low number of fire floors (1–3) failure is dominated by the loss of material strength, while in the cases with larger number of fire floors (5–10) failure is dominated by thermal expansion. Collapse is mainly initiated by the pull-in of external columns (1–3-floor fires; 1–9-floor fires for 2.5% TFM) or swaying of the frame to the side of fire origin (5–10-floor fires). This study has assessed a different structural form compared to previous literature under an extensive range of multiple floor travelling fire scenarios. We find that although vertically travelling fires result in larger beam axial forces and initial deflections, simultaneous travelling fires result in shorter failure times and represent a more onerous scenario for the steel frame investigated.
http://ift.tt/2oVmGTs
IJERPH, Vol. 14, Pages 472: Care-Seeking Patterns and Direct Economic Burden of Injuries in Bangladesh
This study provides a comprehensive review of the care-seeking patterns and direct economic burden of injuries from the victims’ perspective in rural Bangladesh using a 2013 household survey covering 1.17 million people. Descriptive statistics and bivariate analyses were used to derive rates and test the association between variables. An analytic model was used to estimate total injury out-of-pocket (OOP) payments and a multivariate probit regression model assessed the relationship between financial distress and injury type. Results show non-fatal injuries occur to 1 in 5 people in our sample per year. With average household size of 4.5 in Bangladesh--every household has an injury every year. Most non-fatally injured patients sought healthcare from drug sellers. Less than half of fatal injuries sought healthcare and half of those with care were hospitalized. Average OOP payments varied significantly (range: $8–$830) by injury type and outcome (fatal vs. non-fatal). Total injury OOP expenditure was $$355,795 and $5000 for non-fatal and fatal injuries, respectively, per 100,000 people. The majority of household heads with injuries reported financial distress. This study can inform injury prevention advocates on disparities in healthcare usage, OOP costs and financial distress. Reallocation of resources to the most at risk populations can accelerate reduction of preventable injuries and prevent injury related catastrophic payments and impoverishment.
http://ift.tt/2qhJptT
http://ift.tt/2qhJptT
IJERPH, Vol. 14, Pages 473: 6MWT Performance and its Correlations with VO2 and Handgrip Strength in Home-Dwelling Mid-Aged and Older Chinese
Six-minute walk test (6MWT) performance is more commonly used in clinic patients with chronic cardiopulmonary diseases but not in home-dwelling individuals of similar age, and its correlations with oxygen uptake (VO2) and muscle strength require further investigation. The current study determined the 6MWT performance of 106 home-dwelling residents (mean age of 62 years) in Suzhou, China. VO2 at a respiratory exchange ratio (R) of 1 was measured through graded cycling exercise tests on 46 participants. Handgrip strength of all participants was tested. 6MWT distance measured 543.4 ± 67.2 m (total work 351.0 ± 62.8 kJ) with similar distances ambulated each minute. Heart rate, blood pressure, and rate of perceived exertion scores significantly increased after 6MWT. VO2 at R = 1 reached 1238 ± 342 mL/min (18.6 ± 4.7 mL/kg/min), whereas handgrip strength totaled 29.8 ± 9.6 kg. 6MWT distance showed strong correlations with VO2 (r = 0.549, p ≤ 0.001) and handgrip strength (r = 0.359, p < 0.001). Aside from providing reference values for 6MWT performance (~543 m, ~559 m in males and ~533 in females) for home-dwelling Chinese residents, our results suggest that as a parameter of exercise endurance, 6MWT performance correlates with both aerobic capacity and muscle fitness.
http://ift.tt/2pfJ7Fl
http://ift.tt/2pfJ7Fl
IJERPH, Vol. 14, Pages 471: The Relationship of PM Variation with Visibility and Mixing-Layer Height under Hazy/Foggy Conditions in the Multi-Cities of Northeast China
The variations of visibility, PM-mass concentration and mixing-layer height (MLH) in four major urban/industry regions (Shenyang, Anshan, Benxi and Fushun) of central Liaoning in Northeast China are evaluated from 2009 to 2012 to characterize their dynamic effect on air pollution. The annual mean visibilities are about 13.7 ± 7.8, 13.5 ± 6.5, 12.8 ± 6.1 and 11.5 ± 6.8 km in Shenyang, Anshan, Benxi and Fushun, respectively. The pollution load (PM × MLH) shows a weaker vertical diffusion in Anshan, with a higher PM concentration near the surface. High concentrations of fine-mode particles may be partially attributed to the biomass-burning emissions from September in Liaoning Province and surrounding regions in Northeast China as well as the coal burning during the heating period with lower MLH in winter. The visibility on non-hazy fog days is about 2.5–3.0 times higher than that on hazy and foggy days. The fine-particle concentrations of PM2.5 and PM1.0 on hazy and foggy days are ~1.8–1.9 times and ~1.5 times higher than those on non-hazy foggy days. The MLH declined more severely during fog pollution than in haze pollution. The results of this study can provide useful information to better recognize the effects of vertical pollutant diffusion on air quality in the multi-cities of central Liaoning Province in Northeast China.
http://ift.tt/2qfXRp5
http://ift.tt/2qfXRp5
IJERPH, Vol. 14, Pages 439: Developing a Water Quality Index (WQI) for an Irrigation Dam
Pollution levels have been increasing in water ecosystems worldwide. A water quality index (WQI) is an available tool to approximate the quality of water and facilitate the work of decision-makers by grouping and analyzing numerous parameters with a single numerical classification system. The objective of this study was to develop a WQI for a dam used for irrigation of about 5000 ha of agricultural land. The dam, La Vega, is located in Teuchitlan, Jalisco, Mexico. Seven sites were selected for water sampling and samples were collected in March, June, July, September, and December 2014 in an initial effort to develop a WQI for the dam. The WQI methodology, which was recommended by the Mexican National Water Commission (CNA), was used. The parameters employed to calculate the WQI were pH, electrical conductivity (EC), dissolved oxygen (DO), total dissolved solids (TDS), total hardness (TH), alkalinity (Alk), total phosphorous (TP), Cl−, NO3, SO4, Ca, Mg, K, B, As, Cu, and Zn. No significant differences in WQI values were found among the seven sampling sites along the dam. However, seasonal differences in WQI were noted. In March and June, water quality was categorized as poor. By July and September, water quality was classified as medium to good. Quality then decreased, and by December water quality was classified as medium to poor. In conclusion, water treatment must be applied before waters from La Vega dam reservoir can be used for irrigation or other purposes. It is recommended that the water quality at La Vega dam is continually monitored for several years in order to confirm the findings of this short-term study.
http://ift.tt/2qhZiAw
http://ift.tt/2qhZiAw
IJERPH, Vol. 14, Pages 474: Accessing Disadvantaged Pregnant Women in Houston, Texas, and Characterizing Biomarkers of Metal Exposure: A Feasibility Study
Abstract: Communities of color or low socioeconomic status are disproportionately affected by metal exposure given spatial variability of the ambient levels of these contaminants. Despite this, there is little research characterizing metal concentrations in blood among disadvantaged populations in the U.S., especially among pregnant women who are particularly vulnerable and difficult to access. Thus, we conducted a pilot study among disadvantaged pregnant women in Houston, Texas to assess willingness to participate in key activities of an epidemiologic study and characterize exposures to 16 metals. Thirty-one women attending a Medicaid-serving prenatal clinic were included in this pilot study and completed an interviewer-administered questionnaire. We obtained and measured metal compounds in whole blood samples for 22 of these women during third-trimester prenatal visits. Median whole blood concentrations of Ni, As, Cd, and Pb were 27, 1.4, 0.6, and 6.3 µg/L, respectively. Most women were willing to participate in critical aspects of a research study, including wearing a personal air-sampling badge for 2–3 days (87.1%), receiving ultrasounds (83.9%), and providing blood draws (64.5%). Despite the small sample, our results provide evidence of women’s metal exposure and their willingness to participate in future research studies to elucidate exposure pathways and explore related health effects experienced among this population of disadvantaged pregnant women.
http://ift.tt/2prl98Q
http://ift.tt/2prl98Q
Παρασκευή 28 Απριλίου 2017
Comprehensive wind tunnel experiments of lofting and downwind transport of non-combusting rod-like model firebrands during firebrand shower scenarios
Publication date: June 2017
Source:Fire Safety Journal, Volume 90
Author(s): Ali Tohidi, Nigel Berkeley Kaye
To date, due to difficulties in making measurements during wildfires, much of what is known about firebrand showers and the subsequent fire spotting comes from mathematical modeling of the lofting and downwind transport of firebrands. However, these models lack experimental validation. Hence, the coupled lofting and downwind transport of non-combusting rod-like firebrands is experimentally modeled by releasing them through the velocity field of a large scale boundary layer wind tunnel. Complete trajectories of model firebrands are resolved using image processing algorithms. The results show a strong positive correlation between the maximum rise height (zmax) and the landing location (xl) of model firebrands. In addition, it is shown that, given the velocity field, the empirical probability density functions (PDF) of xl/zmax are similar regardless of the firebrands' aspect ratio. This implies that the lofting and downwind transport processes cannot be decoupled in transport models. Analysis of the data reveals that, the larger the aspect ratio of firebrands, the more sensitive their landing locations are to the variability in the velocity field through which they are released. The data set presented herein serves as the most comprehensive experimental evidence for not only firebrand transport studies but also for validating mathematical models for the flight of rod-like debris/brands within the velocity field of other extreme events such as hurricanes.
http://ift.tt/2oSCwy3
Source:Fire Safety Journal, Volume 90
Author(s): Ali Tohidi, Nigel Berkeley Kaye
To date, due to difficulties in making measurements during wildfires, much of what is known about firebrand showers and the subsequent fire spotting comes from mathematical modeling of the lofting and downwind transport of firebrands. However, these models lack experimental validation. Hence, the coupled lofting and downwind transport of non-combusting rod-like firebrands is experimentally modeled by releasing them through the velocity field of a large scale boundary layer wind tunnel. Complete trajectories of model firebrands are resolved using image processing algorithms. The results show a strong positive correlation between the maximum rise height (zmax) and the landing location (xl) of model firebrands. In addition, it is shown that, given the velocity field, the empirical probability density functions (PDF) of xl/zmax are similar regardless of the firebrands' aspect ratio. This implies that the lofting and downwind transport processes cannot be decoupled in transport models. Analysis of the data reveals that, the larger the aspect ratio of firebrands, the more sensitive their landing locations are to the variability in the velocity field through which they are released. The data set presented herein serves as the most comprehensive experimental evidence for not only firebrand transport studies but also for validating mathematical models for the flight of rod-like debris/brands within the velocity field of other extreme events such as hurricanes.
http://ift.tt/2oSCwy3
Effect of preloading in high-strength bolts on bolted-connections exposed to fire
Publication date: June 2017
Source:Fire Safety Journal, Volume 90
Author(s): Zhen Guo, Nan Lu, Fei Zhu, Rui Gao
Preloading is an important process for bolted connections. Previous studies over the last few decades investigated the fire behaviour of typical bolted connections. However, there is a paucity of studies that examine the effects of preloading in high-strength bolts with respect to the responses of bolted connections that are exposed to fire. This study includes a series of numerical analyses to investigate the fire behaviour of two types of bolted connections, namely extended endplate connections and fin plate connections with and without preloading. Various parameters including preloading and thickness of the connecting plate were considered. The study also demonstrates numerical methodology with respect to preloading and parameters of the damage index by using an explicit dynamic solver. The failure modes, mid-span deflections, displacements of beam ends, and fire-induced axial forces in beams are also discussed in detail. The results indicate that preloading in the bolts has little or no effect on the response of endplate connections exposed to fire because the preloading in endplate connections is offset at the thermal expansion stage. In contrast, the fire behaviour of the fin plate connections is influenced by preloading and fin plate thickness. The use of a thinner fin plate results in the connections receiving a limited effect from the preloading in the connections in fire. The use of a stronger connecting plate in fin plate connections indicates that it is not possible to ignore the effect of preloading on the fire response of connections, and this can improve safety.
http://ift.tt/2oEphVR
Source:Fire Safety Journal, Volume 90
Author(s): Zhen Guo, Nan Lu, Fei Zhu, Rui Gao
Preloading is an important process for bolted connections. Previous studies over the last few decades investigated the fire behaviour of typical bolted connections. However, there is a paucity of studies that examine the effects of preloading in high-strength bolts with respect to the responses of bolted connections that are exposed to fire. This study includes a series of numerical analyses to investigate the fire behaviour of two types of bolted connections, namely extended endplate connections and fin plate connections with and without preloading. Various parameters including preloading and thickness of the connecting plate were considered. The study also demonstrates numerical methodology with respect to preloading and parameters of the damage index by using an explicit dynamic solver. The failure modes, mid-span deflections, displacements of beam ends, and fire-induced axial forces in beams are also discussed in detail. The results indicate that preloading in the bolts has little or no effect on the response of endplate connections exposed to fire because the preloading in endplate connections is offset at the thermal expansion stage. In contrast, the fire behaviour of the fin plate connections is influenced by preloading and fin plate thickness. The use of a thinner fin plate results in the connections receiving a limited effect from the preloading in the connections in fire. The use of a stronger connecting plate in fin plate connections indicates that it is not possible to ignore the effect of preloading on the fire response of connections, and this can improve safety.
http://ift.tt/2oEphVR
Model parameter sensitivity and benchmarking of the explicit dynamic solver of LS-DYNA for structural analysis in case of fire
Publication date: June 2017
Source:Fire Safety Journal, Volume 90
Author(s): Egle Rackauskaite, Panagiotis Kotsovinos, Guillermo Rein
Due to the complex nature of structural response in fire, computational tools are often necessary for the safe design of structures under fire conditions. In recent years, use of the finite element code LS-DYNA has grown considerably in research and industry for structural fire analysis, but there is no benchmarking of the code available in the fire science literature for such applications. Moreover, due to the quasi-static nature of structural response in fire, the majority of the computational structural fire studies in the literature are based on the use of static solvers. Thus, this paper aims at benchmarking the explicit dynamic solver of LS-DYNA for structural fire analysis against other static numerical codes and experiments. A parameter sensitivity study is carried out to study the effects of various numerical parameters on the convergence to quasi-static solutions. Four canonical problems that encompass a range of thermal and mechanical behaviours in fire are simulated. In addition, two different modelling approaches of composite action between the concrete slab and the steel beams are investigated. In general, the results confirm that when numerical parameters are carefully considered such as to not induce excessive inertia forces in the system, explicit dynamic analyses using LS-DYNA provide good predictions of the key variables of structural response during fire.
http://ift.tt/2oSR0hg
Source:Fire Safety Journal, Volume 90
Author(s): Egle Rackauskaite, Panagiotis Kotsovinos, Guillermo Rein
Due to the complex nature of structural response in fire, computational tools are often necessary for the safe design of structures under fire conditions. In recent years, use of the finite element code LS-DYNA has grown considerably in research and industry for structural fire analysis, but there is no benchmarking of the code available in the fire science literature for such applications. Moreover, due to the quasi-static nature of structural response in fire, the majority of the computational structural fire studies in the literature are based on the use of static solvers. Thus, this paper aims at benchmarking the explicit dynamic solver of LS-DYNA for structural fire analysis against other static numerical codes and experiments. A parameter sensitivity study is carried out to study the effects of various numerical parameters on the convergence to quasi-static solutions. Four canonical problems that encompass a range of thermal and mechanical behaviours in fire are simulated. In addition, two different modelling approaches of composite action between the concrete slab and the steel beams are investigated. In general, the results confirm that when numerical parameters are carefully considered such as to not induce excessive inertia forces in the system, explicit dynamic analyses using LS-DYNA provide good predictions of the key variables of structural response during fire.
http://ift.tt/2oSR0hg
Impact of melting and burnout of polypropylene fibre on air permeability and mechanical properties of high-strength concrete
Publication date: Available online 28 April 2017
Source:Fire Safety Journal
Author(s): Jaeyoung Lee, Keisuke Terada, Masahiro Yamazaki, Kazunori Harada
This study intends to investigate the impact of high temperature, melting and burnout of Polypropylene Fibre (PP fibre) on mechanical properties, pore size distribution and air permeability of high strength concrete. The specimens were high-strength concrete with 120MPa strength produced with a water-binder ratio of 20%. To examine the effects of melting and burnout of the PP fibre, the experiment was conducted using two mixtures. One mixture contained 1.5kg/m3 of PP fibre, while the other did not contain any PP fibre. Heating temperatures were set to room temperature (RT), 120, 200, 300 and 400°C, considering the temperatures for the melting and burnout of the PP fibre. After heating and cooling, compression tests were carried out on the concrete specimens to measure the modulus of elasticity and Poisson's ratio. Pore size distribution was measured using the fragments created by the compression tests. Air permeability was estimated by measuring the pore size distribution. It was found that melting and burnout of the fibre did not affect the compressive strength and modulus of elasticity but the Poisson's ratio of the specimens containing fibres increased at 400°C. The effect of melting and burnout of fibre on pore volume and air permeability is quite small. If it is assumed that micro-cracks affected the air permeability, it is expected that high strength concrete with a large fibre content should create many micro-cracks at high temperature, leading to an increase of air permeability.
http://ift.tt/2oE8l1o
Source:Fire Safety Journal
Author(s): Jaeyoung Lee, Keisuke Terada, Masahiro Yamazaki, Kazunori Harada
This study intends to investigate the impact of high temperature, melting and burnout of Polypropylene Fibre (PP fibre) on mechanical properties, pore size distribution and air permeability of high strength concrete. The specimens were high-strength concrete with 120MPa strength produced with a water-binder ratio of 20%. To examine the effects of melting and burnout of the PP fibre, the experiment was conducted using two mixtures. One mixture contained 1.5kg/m3 of PP fibre, while the other did not contain any PP fibre. Heating temperatures were set to room temperature (RT), 120, 200, 300 and 400°C, considering the temperatures for the melting and burnout of the PP fibre. After heating and cooling, compression tests were carried out on the concrete specimens to measure the modulus of elasticity and Poisson's ratio. Pore size distribution was measured using the fragments created by the compression tests. Air permeability was estimated by measuring the pore size distribution. It was found that melting and burnout of the fibre did not affect the compressive strength and modulus of elasticity but the Poisson's ratio of the specimens containing fibres increased at 400°C. The effect of melting and burnout of fibre on pore volume and air permeability is quite small. If it is assumed that micro-cracks affected the air permeability, it is expected that high strength concrete with a large fibre content should create many micro-cracks at high temperature, leading to an increase of air permeability.
http://ift.tt/2oE8l1o
Fire response of exterior reinforced concrete beam-column subassemblages
Publication date: Available online 28 April 2017
Source:Fire Safety Journal
Author(s): Mohammad Mahdi Raouffard, Minehiro Nishiyama
Investigating the structural response of reinforced concrete beam-column sub-assemblies at elevated temperatures is the purpose of this paper. This goal was achieved by conducting the ISO-834 standard fire test on two identical one-third scaled reinforced concrete beam-column subassemblage test specimens. The test specimens, which each consisted of one reinforced concrete cantilever beam anchored at the mid-height of a reinforced concrete column, were installed together in a full scale furnace and subjected to downward and upward service loads, respectively. The fire compartment fully engulfed the cantilever beams (except the beams’ top face and the loading points), the beam-column connections and the lower columns. The fire test terminated after 74min as soon as the tensile longitudinal steel bars of the upward-loaded cantilever beam attained the predefined critical temperature 530°C. The lower columns exhibited partial concrete spalling and typical diagonal cracks appeared at the beam-column connections. Based on the recorded internal temperature distributions at the joint cores it was found that the material strength loss in the fire had insignificant impact on the load bearing mechanism of the joints. On the other hand, the gradual decrease in rotation capacity of the beam ends during the fire course considerably influenced the load-deflection relationship. A detailed numerical work has been carried out to simulate the response of the test specimens and will be published elsewhere.
http://ift.tt/2oSvYzr
Source:Fire Safety Journal
Author(s): Mohammad Mahdi Raouffard, Minehiro Nishiyama
Investigating the structural response of reinforced concrete beam-column sub-assemblies at elevated temperatures is the purpose of this paper. This goal was achieved by conducting the ISO-834 standard fire test on two identical one-third scaled reinforced concrete beam-column subassemblage test specimens. The test specimens, which each consisted of one reinforced concrete cantilever beam anchored at the mid-height of a reinforced concrete column, were installed together in a full scale furnace and subjected to downward and upward service loads, respectively. The fire compartment fully engulfed the cantilever beams (except the beams’ top face and the loading points), the beam-column connections and the lower columns. The fire test terminated after 74min as soon as the tensile longitudinal steel bars of the upward-loaded cantilever beam attained the predefined critical temperature 530°C. The lower columns exhibited partial concrete spalling and typical diagonal cracks appeared at the beam-column connections. Based on the recorded internal temperature distributions at the joint cores it was found that the material strength loss in the fire had insignificant impact on the load bearing mechanism of the joints. On the other hand, the gradual decrease in rotation capacity of the beam ends during the fire course considerably influenced the load-deflection relationship. A detailed numerical work has been carried out to simulate the response of the test specimens and will be published elsewhere.
http://ift.tt/2oSvYzr
Early fire detection: Are hydrogen sensors able to detect pyrolysis of house hold materials?
Publication date: Available online 28 April 2017
Source:Fire Safety Journal
Author(s): Simone Krüger, Marie-Claire Despinasse, Tina Raspe, Kai Nörthemann, Werner Moritz
We analysed the hydrogen generation during the smouldering of polymeric materials, which are typically used in the household, in the Smoke Density Chamber coupled to a new developed hydrogen sensor to detect early stages of fires. The results of hydrogen generation were compared with the emission of carbon monoxide and smoke during the fire scenarios. Additionally, the results were compared with parameters used in traditional commercial detection systems. In this scenario, the hydrogen sensor showed encouraging results for the detection of fires in earlier phase compared to traditional detectors. Furthermore, we tested the new developed hydrogen sensor in a real room with different fire scenarios. We have also investigated interferences, e.g. steam and cigarette smoke. The hydrogen sensor could detect hydrogen generation in the earliest stage of fire, even before CO and smoke were developed in detectable amounts. Therefore, the hydrogen sensor can be applied for early fire detection in case of pyrolysis. The sensors are quite good for detecting pyrolysis gases. But when it comes to a fast ignition other techniques are more suitable for it. The sensors are best for combination with other techniques, such as smoke detectors.
http://ift.tt/2oE7SMR
Source:Fire Safety Journal
Author(s): Simone Krüger, Marie-Claire Despinasse, Tina Raspe, Kai Nörthemann, Werner Moritz
We analysed the hydrogen generation during the smouldering of polymeric materials, which are typically used in the household, in the Smoke Density Chamber coupled to a new developed hydrogen sensor to detect early stages of fires. The results of hydrogen generation were compared with the emission of carbon monoxide and smoke during the fire scenarios. Additionally, the results were compared with parameters used in traditional commercial detection systems. In this scenario, the hydrogen sensor showed encouraging results for the detection of fires in earlier phase compared to traditional detectors. Furthermore, we tested the new developed hydrogen sensor in a real room with different fire scenarios. We have also investigated interferences, e.g. steam and cigarette smoke. The hydrogen sensor could detect hydrogen generation in the earliest stage of fire, even before CO and smoke were developed in detectable amounts. Therefore, the hydrogen sensor can be applied for early fire detection in case of pyrolysis. The sensors are quite good for detecting pyrolysis gases. But when it comes to a fast ignition other techniques are more suitable for it. The sensors are best for combination with other techniques, such as smoke detectors.
http://ift.tt/2oE7SMR
IJERPH, Vol. 14, Pages 470: Does Unstable Employment Have an Association with Suicide Rates among the Young?
Although a growing body of literature has indicated that unemployment has a positive association with suicide, the dynamic aspects of unstable employment have not yet been considered in suicidology. This study explored the association between employment stability and completed suicide among people aged 25–34 years in 20 OECD (Organization for Economic Cooperation and Development) countries with time-series data (1994–2010). In order to consider the different aspects of unstable employment, we tested the impacts of employment protection legislation indicators as another proxy of job insecurity (employed, but unstable) apart from unemployment rates. Covariates, including economic growth rates, GDP per capita, fertility rates, and divorce rate, were controlled for. The analysis was designed to be gender- and age-specific, where observations with ages of 25–29 were separated from those with ages of 30–34. Random effect models were applied to examine changes over time in suicide rates, and other models were presented to check robustness. The results showed that it is a low level of employment protection, rather than unemployment itself, that was associated with increased suicide rates among all of the studied populations. The magnitude of the effect differed by gender.
http://ift.tt/2qeeGk7
http://ift.tt/2qeeGk7
Πέμπτη 27 Απριλίου 2017
IJERPH, Vol. 14, Pages 468: Assessing Greenhouse Gas Emissions and Health Co-Benefits: A Structured Review of Lifestyle-Related Climate Change Mitigation Strategies
This is the first structured review to identify and summarize research on lifestyle choices that improve health and have the greatest potential to mitigate climate change. Two literature searches were conducted on: (1) active transport health co-benefits, and (2) dietary health co-benefits. Articles needed to quantify both greenhouse gas emissions and health or nutrition outcomes resulting from active transport or diet changes. A data extraction tool (PRISMA) was created for article selection and evaluation. A rubric was devised to assess the biases, limitations and uncertainties of included articles. For active transport 790 articles were retrieved, nine meeting the inclusion criteria. For diet 2524 articles were retrieved, 23 meeting the inclusion criteria. A total of 31 articles were reviewed and assessed using the rubric, as one article met the inclusion criteria for both active transport and diet co-benefits. Methods used to estimate the effect of diet or active transport modification vary greatly precluding meta-analysis. The scale of impact on health and greenhouse gas emissions (GHGE) outcomes depends predominately on the aggressiveness of the diet or active transport scenario modelled, versus the modelling technique. Effective mitigation policies, infrastructure that supports active transport and low GHGE food delivery, plus community engagement are integral in achieving optimal health and GHGE outcomes. Variation in culture, nutritional and health status, plus geographic density will determine which mitigation scenario(s) best suit individual communities.
http://ift.tt/2qiqiPt
http://ift.tt/2qiqiPt
IJERPH, Vol. 14, Pages 469: Prospective Study on the Impact of Fear of Falling on Functional Decline among Community Dwelling Elderly Women
Fear of falling (FOF) is expected to have effects on functional decline in the elderly. In this study, we examined over 2 years the effect of change in FOF on functional decline in community dwelling elderly. We conducted a secondary analysis using data from elderly women, 70 years of age and older, who participated in the Korean Longitudinal Study of Aging (KLoSA). Participants were divided into four categories according to change in FOF between the 2010 and 2012 surveys. Multiple logistic regression analysis was conducted regarding the effects of changes in FOF on functional decline after controlling for variables as known risk factors for functional decline. Rates of functional decline were highest in the “consistently having FOF” group, whereas they were lowest in the “consistently no FOF” group in both 2010 and 2012. Characteristics independently associated with functional decline were change in FOF, depressive symptoms, low frequency of meeting friends, and fear-induced activity avoidance. Longer exposure to FOF was associated with an increased risk of functional decline. FOF is an important health problem that deserves attention in its own right. Public health approaches for elderly persons should address early detection, prevention, and intervention programs for FOF.
http://ift.tt/2plhGZb
http://ift.tt/2plhGZb
The theoretical framework of fire safety design: Reflections and alternatives
Publication date: Available online 27 April 2017
Source:Fire Safety Journal
Author(s): Jonatan Gehandler
This article aims to contribute to discussions and reflections upon the practice and theory of fire safety design. Are we reaching the results we want by the best available means? The theoretical framework of fire safety design is today restricted by a linear design process where mainly quantitative data and methods matters. A deterministic approach to safety ignores the decision-making context and considers each objective in isolation. Alternative methods for the fire safety design could view the design work as an iterative problem solving process between the designers and the stakeholders. Then decision making theory can be applied to solve the problem. In the iterative process key objectives are identified and the problem and its solutions are being reframed, creative inherently safer (cannot fail) and fail safe (forgiving to errors) alternatives are initially aimed at. Design should further embrace a function-centred view of the human-technology-structure system. A utilitarian evaluation that includes also qualitative factors can identify the best trade-offs between conflicting objectives. With a diversity of perspectives on fire safety design, the field of fire safety will be strengthened and be able to assist a rapidly changing world.
http://ift.tt/2pCJMlD
Source:Fire Safety Journal
Author(s): Jonatan Gehandler
This article aims to contribute to discussions and reflections upon the practice and theory of fire safety design. Are we reaching the results we want by the best available means? The theoretical framework of fire safety design is today restricted by a linear design process where mainly quantitative data and methods matters. A deterministic approach to safety ignores the decision-making context and considers each objective in isolation. Alternative methods for the fire safety design could view the design work as an iterative problem solving process between the designers and the stakeholders. Then decision making theory can be applied to solve the problem. In the iterative process key objectives are identified and the problem and its solutions are being reframed, creative inherently safer (cannot fail) and fail safe (forgiving to errors) alternatives are initially aimed at. Design should further embrace a function-centred view of the human-technology-structure system. A utilitarian evaluation that includes also qualitative factors can identify the best trade-offs between conflicting objectives. With a diversity of perspectives on fire safety design, the field of fire safety will be strengthened and be able to assist a rapidly changing world.
http://ift.tt/2pCJMlD
Assessing fire safety using complex numerical models with a Bayesian multi-fidelity approach
Publication date: Available online 26 April 2017
Source:Fire Safety Journal
Author(s): Rémi Stroh, Julien Bect, Séverine Demeyer, Nicolas Fischer, Damien Marquis, Emmanuel Vazquez
Nowadays, fire safety engineers are increasingly relying on sophisticated numerical simulators, typically based on Computational Fluid Dynamics (CFD) solvers, to conduct their analyses. However, the complexity of these numerical models often limits drastically the number of simulations that can be afforded, making traditional methods of safety analysis difficult or impossible to apply. This paper proposes a statistical method to evaluate a quantity of interest with an expensive simulator while saving computation time. The method is based on Bayesian statistics and multi-fidelity. We use Gaussian process regression to construct a Bayesian model of the complex simulator. This model is based on a multi-fidelity approach, which consists in simulating at different levels of accuracy, for instance by varying the spatial discretization in a CFD solver. We illustrate the method on an example of fire safety analysis, where the quantity of interest is the probability of exceeding a tenability threshold in a building on fire.
http://ift.tt/2pldHMj
Source:Fire Safety Journal
Author(s): Rémi Stroh, Julien Bect, Séverine Demeyer, Nicolas Fischer, Damien Marquis, Emmanuel Vazquez
Nowadays, fire safety engineers are increasingly relying on sophisticated numerical simulators, typically based on Computational Fluid Dynamics (CFD) solvers, to conduct their analyses. However, the complexity of these numerical models often limits drastically the number of simulations that can be afforded, making traditional methods of safety analysis difficult or impossible to apply. This paper proposes a statistical method to evaluate a quantity of interest with an expensive simulator while saving computation time. The method is based on Bayesian statistics and multi-fidelity. We use Gaussian process regression to construct a Bayesian model of the complex simulator. This model is based on a multi-fidelity approach, which consists in simulating at different levels of accuracy, for instance by varying the spatial discretization in a CFD solver. We illustrate the method on an example of fire safety analysis, where the quantity of interest is the probability of exceeding a tenability threshold in a building on fire.
http://ift.tt/2pldHMj
IJERPH, Vol. 14, Pages 467: Viability of Legionella pneumophila in Water Samples: A Comparison of Propidium Monoazide (PMA) Treatment on Membrane Filters and in Liquid
Legionella pneumophila is a ubiquitous microorganism widely distributed in aquatic environments and can cause Legionellosis in humans. A promising approach to detect viable cells in water samples involves the use of quantitative polymerase chain reaction (qPCR) in combination with photoactivatable DNA intercalator propidium monoazide (PMA). However, the PMA efficiency could be different depending on the experimental conditions used. The aim of this study was to compare two PMA exposure protocols: (A) directly on the membrane filter or (B) in liquid after filter washing. The overall PMA-induced qPCR means reductions in heat-killed L. pneumophila cells were 2.42 and 1.91 log units for exposure protocols A and B, respectively. A comparison between the results obtained reveals that filter exposure allows a higher PMA-qPCR signal reduction to be reached, mainly at low concentrations (p < 0.05). This confirms the potential use of this method to quantify L. pneumophila in water with low contamination.
http://ift.tt/2p6RYch
http://ift.tt/2p6RYch
IJERPH, Vol. 14, Pages 463: Does an Empty Nest Affect Elders’ Health? Empirical Evidence from China
The “empty-nest” elderly family has become increasingly prevalent among old people in China. This study aimed to explore the causality between empty nests and elders’ health using effective instrumental variables, including “whether old parents talk with their families when they are upset” and “ownership of housing”. The results showed that empty nests had a significantly adverse influence on elders’ physical health, cognitive ability and psychological health. Furthermore, urban elders’ cognitive ability was more influenced by empty nests than that of rural elders. Additionally, the effects of an empty nest on elders” health were more significant among female, single elders and senior rural elders. “Living resources”, “availability of medical treatment” and “social activity engagement” were found to be significant mediators between empty nests and elders’ health, accounting for 35% of the total effect.
http://ift.tt/2oM9ijI
http://ift.tt/2oM9ijI
IJERPH, Vol. 14, Pages 465: Prevalence and Correlates of Suspected Nonalcoholic Fatty Liver Disease in Chinese Children
Nonalcoholic fatty liver disease (NAFLD) has become a serious public health problem worldwide; however, the availability of information on the prevalence of NAFLD in the general pediatric population is still limited. The primary aim of this study was to reveal the prevalence and correlates of suspected NAFLD in Chinese children at the national level. Data from the China Health and Nutrition Surveys (CHNS) was used. Weight, height, waist circumference (WC), blood pressure (BP) were measured for children aged 7–18 years. Blood samples were collected and analyzed. Children were classified as having suspected NAFLD if common causes of liver disease were excluded, and serum alanine aminotransferase (ALT) values were above the established thresholds (>22.1 IU/L for girls and >25.8 IU/L for boys). A percentage of 9.03% (75 out of 831) of Chinese children was found to have suspected NAFLD. Overweight and obesity according to BMI percentiles, abdominal obesity, hyperuricemia (uric acid (UA) > 327 μmol/L), and elevated total cholesterol (TC) were all detected as the correlates of childhood suspected NAFLD when adjusting for other factors. Our study revealed the prevalence of suspected NAFLD in general Chinese children at the national level for the first time. Our findings indicate that suspected NAFLD in children is associated with increasing childhood morbidities, further studies are needed to better understand the prevalence of childhood NAFLD and its correlates, and large-scale programs should be launched to screen NAFLD in the pediatric population in China.
http://ift.tt/2oyWCBe
http://ift.tt/2oyWCBe
Τετάρτη 26 Απριλίου 2017
IJERPH, Vol. 14, Pages 461: Association of Long-Term Near-Highway Exposure to Ultrafine Particles with Cardiovascular Diseases, Diabetes and Hypertension
Ultrafine particle (UFP) concentrations are elevated near busy roadways, however, their effects on prevalence of cardiovascular diseases, diabetes, and hypertension are not well understood. To investigate these associations, data on demographics, diseases, medication use, and time of activities were collected by in-home surveys for 704 participants in three pairs of near-highway and urban background neighborhoods in and near Boston (MA, USA). Body mass index (BMI) was measured for a subset of 435 participants. Particle number concentration (PNC, a measure of UFP) was collected by mobile monitoring in each area. Intra-neighborhood spatial-temporal regression models (approximately 20 m resolution) were used to estimate hourly ambient PNC at the residences of participants. We used participant time activity information to adjust annual average residential PNC values and assign individualized time activity adjusted annual average PNC exposures (TAA-PNC). Using multivariate logistic regression models, we found an odds ratio (OR) of 1.35 (95% CI: 0.83, 2.22) of TAA-PNC with stroke and ischemic heart diseases (S/IHD), an OR of 1.14 (95% CI: 0.81, 1.62) with hypertension, and an OR of 0.71 (95% CI: 0.46, 1.10) for diabetes. A subset analysis controlling for BMI produced slightly stronger associations for S/IHD (OR = 1.61, 95% CI: 0.88, 2.92) and hypertension (OR = 1.28, 95% CI: 0.81, 2.02), and no association with diabetes (OR = 1.09, 95% CI = 0.61, 1.96). Further research is needed with larger sample sizes and longitudinal follow-up.
http://ift.tt/2q57ELF
http://ift.tt/2q57ELF
IJERPH, Vol. 14, Pages 460: Hyponatremia Is Associated with Worse Outcomes from Fall Injuries in the Elderly
Background: Hyponatremia has been proposed as a contributor to falls in the elderly, which have become a major global issue with the aging of the population. This study aimed to assess the clinical presentation and outcomes of elderly patients with hyponatremia admitted due to fall injuries in a Level I trauma center. Methods: We retrospectively reviewed data obtained from the Trauma Registry System for trauma admissions from January 2009 through December 2014. Hyponatremia was defined as a serum sodium level <135 mEq/L, and only patients who had sustained a fall at ground level (<1 m) were included. We used Chi-square tests, Student t-tests, and Mann-Whitney U tests to compare elderly patients (age ≥65 years) with hyponatremia (n = 492) to those without (n = 2002), and to adult patients (age 20–64 years) with hyponatremia (n = 125). Results: Significantly more elderly patients with hyponatremia presented to the emergency department (ED) due to falls compared to elderly patients without hyponatremia (73.7% vs. 52.6%; OR: 2.5, 95% CI: 2.10–3.02; p < 0.001). Elderly patients with hyponatremia presented with a worse outcome, measured by significantly higher odds of intubation (OR: 2.4, 95% CI: 1.15–4.83; p = 0.025), a longer in-hospital length of stay (LOS) (11 days vs. 9 days; p < 0.001), higher proportion of intensive care unit (ICU) admission (20.9% vs. 16.2%; OR: 1.4, 95% CI: 1.07–1.76; p = 0.013), and higher mortality (OR: 2.5, 95% CI: 1.53–3.96; p < 0.001), regardless of adjustment by Injury Severity Scores (ISS) (AOR: 2.4, 95% CI: 1.42–4.21; p = 0.001). Conclusions: Our results show that hyponatremia is associated with worse outcome from fall-related injuries in the elderly, with an increased ISS, longer LOS, and a higher risk of death.
http://ift.tt/2oJrjyP
http://ift.tt/2oJrjyP
IJERPH, Vol. 14, Pages 466: Determinants of Work Performance in Workers with Depression and Anxiety: A Cross-Sectional Study
Depression and anxiety are highly prevalent disorders with an impact on existential aspects of person’s life, including employment i.e., work performance (WP). In order to develop appropriate strategies, it is essential to identify determinants of WP. The objective of this study was to identify the built, social, attitudinal and health system-related environmental determinants of WP in workers with anxiety or depression in total (N = 1211) and regarding the level of disability. Hierarchical binary logistic regression was performed on data obtained from implementation of the WHO Model Disability Survey (MDS) in Chile in 2015. Hindering aspects of means of transportation and workplace, and the use of personal assistance were determinants of WP for all workers with anxiety or depression. Results differed with level of disability. Hindering aspects of means of transportation and workplace, and discrimination were determinants of WP for persons with mild to moderate disability, while hindering aspects of the workplace and dwelling, and the use of personal assistance were determinants of WP for persons with severe disability. Our results emphasize the need for a broader understanding of determinants of WP and the requirement for an integrative approach in developing both universal and specific strategies that go beyond workplace settings.
http://ift.tt/2q759LM
http://ift.tt/2q759LM
The performance of near-surface mounted CFRP strengthened RC beam in fire
Publication date: June 2017
Source:Fire Safety Journal, Volume 90
Author(s): Yu Jiangtao, Wang Yichao, Hu Kexu, Yu Kequan, Xiao Jianzhuang
Carbon fiber reinforced polymers (CFRP) have been widely used in the retrofitting and strengthening of concrete structures. However, the layouts of CFRP in externally bonded (EB) strengthening system and near surface mounted (NSM) system result in the vulnerability of fire resistance. To explore the fire resistance potential of NSM-CFRP strengthening system, 15 RC beams strengthened with CFRP and 2 reference beams were loaded to failure either under the ISO834 standard fire or at ambient temperature. In test, the following factors were considered: the strengthening method (near surface mounted technique/externally bonded technique), adhesive (epoxy and magnesium-oxychloride cement), fire protection materials (thin intumescent fire retardant coating and thick fire retardant coating) and location of fire protection (local patch protection/single-sided protection/U-shaped protection). With appropriate fire protection, the RC beams strengthened with NSM-CFRP resisted the standard fire for more than 3h at high load level. Besides the effects of the aforementioned factors, the friction stress at the CFRP/matrix interface when CFRP is in globally slipping is found playing a crucial role for the fire resistance of NSM-CFRP strengthening system. The experimental observation sheds some light on how the NSM-CFRP strips can retain the contribution at elevated temperatures and why NSM-CFRP strengthening outperforms EB-CFRP strengthening when exposed to fire.
http://ift.tt/2q4OGoE
Source:Fire Safety Journal, Volume 90
Author(s): Yu Jiangtao, Wang Yichao, Hu Kexu, Yu Kequan, Xiao Jianzhuang
Carbon fiber reinforced polymers (CFRP) have been widely used in the retrofitting and strengthening of concrete structures. However, the layouts of CFRP in externally bonded (EB) strengthening system and near surface mounted (NSM) system result in the vulnerability of fire resistance. To explore the fire resistance potential of NSM-CFRP strengthening system, 15 RC beams strengthened with CFRP and 2 reference beams were loaded to failure either under the ISO834 standard fire or at ambient temperature. In test, the following factors were considered: the strengthening method (near surface mounted technique/externally bonded technique), adhesive (epoxy and magnesium-oxychloride cement), fire protection materials (thin intumescent fire retardant coating and thick fire retardant coating) and location of fire protection (local patch protection/single-sided protection/U-shaped protection). With appropriate fire protection, the RC beams strengthened with NSM-CFRP resisted the standard fire for more than 3h at high load level. Besides the effects of the aforementioned factors, the friction stress at the CFRP/matrix interface when CFRP is in globally slipping is found playing a crucial role for the fire resistance of NSM-CFRP strengthening system. The experimental observation sheds some light on how the NSM-CFRP strips can retain the contribution at elevated temperatures and why NSM-CFRP strengthening outperforms EB-CFRP strengthening when exposed to fire.
http://ift.tt/2q4OGoE
A computational study of extinguishment and enhancement of propane cup-burner flames by halon and alternative agents
Publication date: Available online 26 April 2017
Source:Fire Safety Journal
Author(s): Fumiaki Takahashi, Viswanath R. Katta, Gregory T. Linteris, Valeri I. Babushok
Computations of cup-burner flames in normal gravity have been performed using propane as the fuel to reveal the combustion inhibition and enhancement by the CF3Br (halon 1301) and potential alternative fire-extinguishing agents (C2HF5, C2HF3Cl2, and C3H2F3Br). The time-dependent, two-dimensional numerical code used includes a detailed kinetic model (up to 241 species and 3918 reactions), diffusive transport, and a gray-gas radiation model. The peak reactivity spot (i.e., reaction kernel) at the flame base stabilizes a trailing flame, which is inclined inwardly by a buoyancy-induced entrainment flow. As the volume fraction of agent in the coflow increases gradually, the premixed-like reaction kernel weakens, thus inducing the flame base detachment from the burner rim and blowoff-type extinguishment eventually. The two-zone flame structure (with two heat-release-rate peaks) is formed in the trailing diffusion flame. The H2O formed in the inner zone is converted further, primarily in the outer zone, to HF and CF2O through exothermic reactions most significantly with the C2HF5 addition. The total heat release of the entire flame decreases (inhibiting) for CF3Br but increases (enhancing) for the halon alternative agents, particularly C2HF5 and C2HF3Cl2. Addition of C2HF5 results in unusual (non-chain branching) reactions.
http://ift.tt/2pkVhNL
Source:Fire Safety Journal
Author(s): Fumiaki Takahashi, Viswanath R. Katta, Gregory T. Linteris, Valeri I. Babushok
Computations of cup-burner flames in normal gravity have been performed using propane as the fuel to reveal the combustion inhibition and enhancement by the CF3Br (halon 1301) and potential alternative fire-extinguishing agents (C2HF5, C2HF3Cl2, and C3H2F3Br). The time-dependent, two-dimensional numerical code used includes a detailed kinetic model (up to 241 species and 3918 reactions), diffusive transport, and a gray-gas radiation model. The peak reactivity spot (i.e., reaction kernel) at the flame base stabilizes a trailing flame, which is inclined inwardly by a buoyancy-induced entrainment flow. As the volume fraction of agent in the coflow increases gradually, the premixed-like reaction kernel weakens, thus inducing the flame base detachment from the burner rim and blowoff-type extinguishment eventually. The two-zone flame structure (with two heat-release-rate peaks) is formed in the trailing diffusion flame. The H2O formed in the inner zone is converted further, primarily in the outer zone, to HF and CF2O through exothermic reactions most significantly with the C2HF5 addition. The total heat release of the entire flame decreases (inhibiting) for CF3Br but increases (enhancing) for the halon alternative agents, particularly C2HF5 and C2HF3Cl2. Addition of C2HF5 results in unusual (non-chain branching) reactions.
http://ift.tt/2pkVhNL
Effectiveness of vertical barriers in preventing lateral flame spread over exposed EPS insulation wall
Publication date: Available online 26 April 2017
Source:Fire Safety Journal
Author(s): Liang Zhou, Aiping Chen, Lei Gao, Zhifeng Pei
Insulation panels made of organic, combustible materials are frequently used in the exterior thermal insulation systems (ETIS) for buildings. Such combustible insulation panels have been involved in several catastrophic building fires in recent years in China. One potential strategy to mitigate this fire hazard is to limit fire spread over the ETIS. The present work evaluates the effectiveness of vertical fire barriers in inhibiting fire spread over exposed insulation walls made of expanded polystyrene (EPS) panels. Reduced-scale experiments were carried out indoors using EPS panels with or without two vertical barriers made of non-combustible mineral wool, the fire started at the bottom center of the middle panel. The interval and width of the barriers were varied systematically, while the temperature distribution on the wall, the radiation heat flux from the fire, and the infra-red (IR) images were recorded. To demonstrate the validity of the concept, an outdoor, full-scale experiment was carried out using a 7-floor building. Our reduced-scale experiments showed that the installation of two vertical fire barriers successfully stopped the lateral flame spread, decreasing the peak temperatures of the two side panels by about 300°C for all barrier configurations tested. When barrier width was fixed at 5cm, an increase of the barrier interval from 30 to 90cm led to increases in the peak temperatures, radiation heat flux, and the maximum rate of upward flame spread. By contrast, when barrier interval was fixed at 90cm, an increase of the barrier width from 2 to 5cm had little influence on the combustion dynamics of the middle panel but the peak temperature on the side panels dropped, consistent with the smaller heat transferred with wider fire barriers. In the regions of the side panels next to the barriers, pyrolysis and deformation could be observed with barrier widths of 2 and 3cm, but not 5cm. Finally, our outdoor, full-scale experiment demonstrated that a 30cm wide vertical barrier made of air-filled cement successfully stopped the lateral flame spread over exposed EPS wall. The study highlights the effectiveness of vertical fire barriers in preventing the lateral flame spread over the exposed EPS insulation wall and provides another option for enhancing the fire safety of the combustible insulation systems.
http://ift.tt/2q4PJ7N
Source:Fire Safety Journal
Author(s): Liang Zhou, Aiping Chen, Lei Gao, Zhifeng Pei
Insulation panels made of organic, combustible materials are frequently used in the exterior thermal insulation systems (ETIS) for buildings. Such combustible insulation panels have been involved in several catastrophic building fires in recent years in China. One potential strategy to mitigate this fire hazard is to limit fire spread over the ETIS. The present work evaluates the effectiveness of vertical fire barriers in inhibiting fire spread over exposed insulation walls made of expanded polystyrene (EPS) panels. Reduced-scale experiments were carried out indoors using EPS panels with or without two vertical barriers made of non-combustible mineral wool, the fire started at the bottom center of the middle panel. The interval and width of the barriers were varied systematically, while the temperature distribution on the wall, the radiation heat flux from the fire, and the infra-red (IR) images were recorded. To demonstrate the validity of the concept, an outdoor, full-scale experiment was carried out using a 7-floor building. Our reduced-scale experiments showed that the installation of two vertical fire barriers successfully stopped the lateral flame spread, decreasing the peak temperatures of the two side panels by about 300°C for all barrier configurations tested. When barrier width was fixed at 5cm, an increase of the barrier interval from 30 to 90cm led to increases in the peak temperatures, radiation heat flux, and the maximum rate of upward flame spread. By contrast, when barrier interval was fixed at 90cm, an increase of the barrier width from 2 to 5cm had little influence on the combustion dynamics of the middle panel but the peak temperature on the side panels dropped, consistent with the smaller heat transferred with wider fire barriers. In the regions of the side panels next to the barriers, pyrolysis and deformation could be observed with barrier widths of 2 and 3cm, but not 5cm. Finally, our outdoor, full-scale experiment demonstrated that a 30cm wide vertical barrier made of air-filled cement successfully stopped the lateral flame spread over exposed EPS wall. The study highlights the effectiveness of vertical fire barriers in preventing the lateral flame spread over the exposed EPS insulation wall and provides another option for enhancing the fire safety of the combustible insulation systems.
http://ift.tt/2q4PJ7N
Char cracking of medium density fibreboard due to thermal shock effect induced pyrolysis shrinkage
Publication date: Available online 26 April 2017
Source:Fire Safety Journal
Author(s): Kaiyuan Li, Mahmoud Mousavi, Simo Hostikka
Pyrolysis experiments were conducted on medium density fibreboard (MDF) in inert atmosphere and different ambient pressures, to investigate the char shrinkage and cracking. It is found that the char cracking under uniform heat flux is a typical thermal shock process induced by unbalance shrinkage along the sample thickness during pyrolysis. To predict the number of char fissures, the critical stress criterion and energy conservation theory are used to develop mathematical models under plane constitutive stress state, which reveal that under the same surface degradation the number of char fissures (blisters) strongly relates to the pyrolysis depth at cracking time. Increasing external heat flux decreases the pyrolysis depth and increases the number of char fissures. Both experiments and numerical modelling are used to validate the models. The experimental results show that the horizontal shrinkage is 11% of original length and the micro-structure of char fissures of MDF is less uniform compared to the one of natural wood with a cellular pattern. The surface stresses after cracking are found similarly close to the tensile strength under different heat fluxes, while the surface stresses are very different assuming no crack, which indicates the cracking process reduces the surface stress to lower than the tensile strength. The modelled cracking times are different from the observed cracking time as the fissures are hard to identify at its initial stage and only when they have expanded to certain size the fissures are visually observed. Using the modelled cracking time, the number of char blisters can be well correlated with the pyrolysis depth.
http://ift.tt/2pkRIqQ
Source:Fire Safety Journal
Author(s): Kaiyuan Li, Mahmoud Mousavi, Simo Hostikka
Pyrolysis experiments were conducted on medium density fibreboard (MDF) in inert atmosphere and different ambient pressures, to investigate the char shrinkage and cracking. It is found that the char cracking under uniform heat flux is a typical thermal shock process induced by unbalance shrinkage along the sample thickness during pyrolysis. To predict the number of char fissures, the critical stress criterion and energy conservation theory are used to develop mathematical models under plane constitutive stress state, which reveal that under the same surface degradation the number of char fissures (blisters) strongly relates to the pyrolysis depth at cracking time. Increasing external heat flux decreases the pyrolysis depth and increases the number of char fissures. Both experiments and numerical modelling are used to validate the models. The experimental results show that the horizontal shrinkage is 11% of original length and the micro-structure of char fissures of MDF is less uniform compared to the one of natural wood with a cellular pattern. The surface stresses after cracking are found similarly close to the tensile strength under different heat fluxes, while the surface stresses are very different assuming no crack, which indicates the cracking process reduces the surface stress to lower than the tensile strength. The modelled cracking times are different from the observed cracking time as the fissures are hard to identify at its initial stage and only when they have expanded to certain size the fissures are visually observed. Using the modelled cracking time, the number of char blisters can be well correlated with the pyrolysis depth.
http://ift.tt/2pkRIqQ
IJERPH, Vol. 14, Pages 464: Assessing Diabetes and Factors Associated with Foregoing Medical Care among Persons with Diabetes: Disparities Facing American Indian/Alaska Native, Black, Hispanic, Low Income, and Southern Adults in the U.S. (2011–2015)
Objective: Identify individual- and place-based factors associated with diagnosed diabetes and forgone medical care among those diagnosed with diabetes. Background: Diabetes affects millions of individuals globally. In the U.S. alone the prevalence rate of diagnosed diabetes has more than doubled over the past 20 years (4.2% in 1994 to 10% in 2014). Methods: The Behavioral Risk Factor Surveillance System (2011–2015) was used to identify factors associated with self-reported diabetes diagnoses (ever diagnosed) among U.S. adults. Logistic regression modeled: (1) the likelihood of having diabetes; (2) the likelihood of forgone medical care among those with diabetes, given appropriate medical care has been linked to preventing complications associated with diabetes. Results: Rates of diabetes remained relatively stable from 2011 to 2015. The likelihood of diabetes was higher (p < 0.01) among racial and ethnic minority groups, men, those with lower incomes and those with lower education. Place-based disparities indicating a higher likelihood of having a diagnosis of diabetes were found for those living in rural areas (urban versus rural, unadjusted OR = 0.844–0.908; p < 0.01) and those living in the South (North, Midwest, and Western/Pacific regions versus the South, unadjusted OR = 0.794–0.889; p < 0.01). Similar results were found with forgone medical care among those diagnosed with diabetes being more likely in the South (North, Midwest, and Western/Pacific regions versus the South, unadjusted OR = 0.542–0.819). In fully-adjusted analyses, the prevalence of diabetes and forgone medical care among those diagnosed with diabetes was higher for those with lower incomes, from several racial/ethnic minority groups, and in the South versus most other regions. Conclusions: Identifying at-risk groups informs targets for prevention and assists efforts to address chronic disease self-management among those already diagnosed with diabetes.
http://ift.tt/2qdTxmK
http://ift.tt/2qdTxmK
IJERPH, Vol. 14, Pages 462: Impact of Land Use on PM2.5 Pollution in a Representative City of Middle China
Fine particulate matter (PM2.5) pollution has become one of the greatest urban issues in China. Studies have shown that PM2.5 pollution is strongly related to the land use pattern at the micro-scale and optimizing the land use pattern has been suggested as an approach to mitigate PM2.5 pollution. However, there are only a few researches analyzing the effect of land use on PM2.5 pollution. This paper employed land use regression (LUR) models and statistical analysis to explore the effect of land use on PM2.5 pollution in urban areas. Nanchang city, China, was taken as the study area. The LUR models were used to simulate the spatial variations of PM2.5 concentrations. Analysis of variance and multiple comparisons were employed to study the PM2.5 concentration variances among five different types of urban functional zones. Multiple linear regression was applied to explore the PM2.5 concentration variances among the same type of urban functional zone. The results indicate that the dominant factor affecting PM2.5 pollution in the Nanchang urban area was the traffic conditions. Significant variances of PM2.5 concentrations among different urban functional zones throughout the year suggest that land use types generated a significant impact on PM2.5 concentrations and the impact did not change as the seasons changed. Land use intensity indexes including the building volume rate, building density, and green coverage rate presented an insignificant or counter-intuitive impact on PM2.5 concentrations when studied at the spatial scale of urban functional zones. Our study demonstrates that land use can greatly affect the PM2.5 levels. Additionally, the urban functional zone was an appropriate spatial scale to investigate the impact of land use type on PM2.5 pollution in urban areas.
http://ift.tt/2pkRGPJ
http://ift.tt/2pkRGPJ
Τρίτη 25 Απριλίου 2017
Effects of aircraft noise exposure on saliva cortisol near airports in France
Background
http://ift.tt/2q3eYua
Saliva cortisol is a possible marker of noise-induced stress and could then mediate the relation observed between exposure to aircraft or road traffic noise and cardiovascular diseases. However, the association between transportation noise and cortisol levels is still unclear. The objective of the study was to investigate the variability of saliva cortisol concentration as an indicator of disturbed hypothalamus-pituitary-adrenal (HPA) axis regulation in relation to long-term aircraft noise exposure.
MethodsSaliva samples were taken when awakening and before going to bed for 1244 participants older than 18 years of age. Information about health, socioeconomic and lifestyle factors was also collected by means of a face-to-face questionnaire performed at home by an interviewer. Aircraft noise exposure was assessed for each participant’s home address using noise maps. Linear regression models were used to evaluate the effects of aircraft noise exposure on the morning and evening cortisol levels and on the daily variation of cortisol per hour.
ResultsThis study suggests a modification of the cortisol circadian rhythm in relation to aircraft noise exposure. This exposure was associated with a smaller variation of cortisol levels over the day, with unchanged morning cortisol levels, but higher cortisol levels in the evening.
ConclusionsThese findings provide some support for a psychological stress induced by aircraft noise exposure, resulting in HPA dysregulation and a flattened cortisol rhythm, thus contributing to cardiovascular diseases.
http://ift.tt/2q3eYua
Effect of informal employment on the relationship between psychosocial work risk factors and musculoskeletal pain in Central American workers
Introduction
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The constant increase on the psychosocial demands experienced at work seems to contribute to the increase in health problems such as musculoskeletal pain (MSP). This association may be especially important in low-income and middle-income countries, where there is a large proportion of informal workers among whom there is little research. We analysed the association between psychosocial work risk factors and MSP among formal and informal workers using the First Central American Survey of Working Conditions and Health.
MethodsThis is a representative sample (n=12 024) of the economically active population of the six Spanish-speaking countries of Central America. Prevalence ratios (PR) and corresponding 95% CIs from Poisson regression models were used to estimate the association between psychosocial work risk factors and the MSP.
ResultsCompared with formal workers, informal workers reported higher prevalence of MPS in the body regions analysed (ie, cervicodorsal, lumbosacral, upper extremities) and higher exposure to psychosocial work risk factors. However, on the whole, the associations between the exposure to psychosocial work risk factors and the prevalence of MSP were similar for both formal and informal workers. Only the association between exposure to high demands and MSP in the upper extremities was higher (p=0.012) among formal (PR=1.69, 95% CI 1.46 to 1.96) than among informal workers (PR=1.40; 95% CI 1.30 to 1.51).
ConclusionExposure to adverse levels of psychosocial work risk factors is associated with higher prevalence of MPS among both formal and informal workers. However, the role of employment informality in this association is complex and requires further examination.
http://ift.tt/2peSLq6
IJERPH, Vol. 14, Pages 459: Immunization Strategies Targeting Newly Arrived Migrants in Non-EU Countries of the Mediterranean Basin and Black Sea
Background: The World Health Organization recommends that host countries ensure appropriate vaccinations to refugees, asylum seekers and migrants. However, information on vaccination strategies targeting migrants in host countries is limited. Methods: In 2015–2016 we carried out a survey among national experts from governmental bodies of 15 non-EU countries of the Mediterranean and Black Sea in order to document and share national vaccination strategies targeting newly arrived migrants. Results: Four countries reported having regulations/procedures supporting the immunization of migrants at national level, one at sub-national level and three only targeting specific population groups. Eight countries offer migrant children all the vaccinations included in their national immunization schedule; three provide only selected vaccinations, mainly measles and polio vaccines. Ten and eight countries also offer selected vaccinations to adolescents and adults respectively. Eight countries provide vaccinations at the community level; seven give priority vaccines in holding centres or at entry sites. Data on administered vaccines are recorded in immunization registries in nine countries. Conclusions: Although differing among countries, indications for immunizing migrants are in place in most of them. However, we cannot infer from our findings whether those strategies are currently functioning and whether barriers to their implementation are being faced. Further studies focusing on these aspects are needed to develop concrete and targeted recommendations for action. Since migrants are moving across countries, development of on-line registries and cooperation between countries could allow keeping track of administered vaccines in order to appropriately plan immunization series and avoid unnecessary vaccinations.
http://ift.tt/2pek3Nh
http://ift.tt/2pek3Nh
IJERPH, Vol. 14, Pages 456: Levels and Distribution of Pollutants in the Waters of an Aquatic Ecosystem in Northern Mexico
The availability of good quality water resources is essential to ensure healthy crops and livestock. The objective of this study was to evaluate the level of pollution in Bustillos Lagoon in northern Mexico. Physical-chemical parameters like sodium, chloride, sulfate, electrical conductivity, nitrates, and the pesticide dichlorodiphenyltrichloroethane (DDT) were analyzed to determine the water quality available in the lagoon. Although DDT has been banned in several countries, it is still used for agricultural purposes in Mexico and its presence in this area had not been analyzed previously. Bustillos Lagoon was divided into three zones for the evaluation: (1) industrial; (2) communal lands; and (3) agricultural. The highest concentrations of sodium (2360 mg/L) and SAR (41 meq/L) reported in the industrial zone are values exceeding the United Nations Food and Agricultural Organization (FAO) irrigation water quality guidelines. DDT and its metabolites were detected in all of the 21 sites analyzed, in the agricultural zone ∑DDTs = 2804 ng/mL, this level is much higher than those reported for other water bodies in Mexico and around the world where DDT has been used heavily. The water in the communal zone is the least contaminated, but can only be recommended for irrigation of plants with high stress tolerance and not for crops.
http://ift.tt/2peh5bC
http://ift.tt/2peh5bC
IJERPH, Vol. 14, Pages 458: Association between Sleep and Body Weight: A Panel Data Model Based on a Retrospective Longitudinal Cohort of Chinese Infants
The focus of this article is on sleep duration and sleep problems in infants and their association with body weight. A retrospective birth cohort of 519 infants was enrolled in a community-based study conducted in Changsha, China. Infant weight and other health-related information were collected during regular standard checkups at the Community Health Service Centers when infants were 1, 3, 6, 8, and 12 months old. The sleep duration and sleep problems of infants were assessed by maternal self-reports. Panel data model was used to evaluate the association of sleep duration and sleep problems with infant body weight. Significant relevance between self-reported sleep duration and weight of infants has been reported in the literature tested by the fixed effects model (p < 0.01). However, this study indicated that sleep problems of infants had no effect on their weight (p = 0.151), after adjusting feeding patterns and socioeconomic factors of their families. This paper argues that, as a potentially modifiable risk factor, infant sleep duration deserves more attention from their parents and families in order to prevent and control overweight or obesity in infants as well as reducing the incidence of obesity in adults.
http://ift.tt/2pek2ZW
http://ift.tt/2pek2ZW
Predicting the heat release rates of liquid pool fires in mechanically ventilated compartments
Publication date: Available online 25 April 2017
Source:Fire Safety Journal
Author(s): Topi Sikanen, Simo Hostikka
In this paper we perform predictive simulations of liquid pool fires in mechanically ventilated compartments. We show that steady state burning rates are accurately predicted using a detailed model for the liquid phase heat transfer. The effect of lowered oxygen vitiation on the burning rate of pool fires is correctly captured. Simulations were done using the Fire Dynamics Simulator and the experiments considered were conducted in the OECD PRISME project. The main difference between the present study and previous simulation studies is the use of a detailed liquid evaporation model and the direct calculation of the vitiation and thermal environment interactions through the CFD solver.
http://ift.tt/2p0Eqz9
Source:Fire Safety Journal
Author(s): Topi Sikanen, Simo Hostikka
In this paper we perform predictive simulations of liquid pool fires in mechanically ventilated compartments. We show that steady state burning rates are accurately predicted using a detailed model for the liquid phase heat transfer. The effect of lowered oxygen vitiation on the burning rate of pool fires is correctly captured. Simulations were done using the Fire Dynamics Simulator and the experiments considered were conducted in the OECD PRISME project. The main difference between the present study and previous simulation studies is the use of a detailed liquid evaporation model and the direct calculation of the vitiation and thermal environment interactions through the CFD solver.
http://ift.tt/2p0Eqz9
Perspectives of occupants with mobility impairments on evacuation methods for use during fire emergencies
Publication date: Available online 24 April 2017
Source:Fire Safety Journal
Author(s): Kathryn Butler, Erica Kuligowski, Susanne Furman, Richard Peacock
Since the tragic loss of life in the World Trade Center disaster, efforts have refocused on the provision of safe and efficient evacuation procedures, especially for occupants who cannot negotiate exit stairs without assistance. Several evacuation options have been designed specifically for people with mobility impairments, including occupant evacuation elevators (OEEs). Face-to-face interviews were conducted with 51 participants with mobility impairments working in buildings located in five major metropolitan areas within the U.S. The dual goals in this study were to gain an understanding of how building occupants with mobility impairments evacuate multi-story buildings during fire emergencies and to identify perspectives on the use of elevators during fire evacuations. Data analysis of interviews highlighted the benefits and concerns of study participants involving both typical building evacuation methods (i.e., emergency stair travel devices and areas of refuge), as well as evacuation methods using elevators. This study also highlights improvements that can be made to elevator systems, particularly OEEs, to reduce anxiety about fire evacuation and increase trust in the occupant evacuation elevator system via a variety of means, including education and consultation in preparation for the evacuation, information and attention to occupant needs while the evacuation is taking place, and two-way feedback and discussions afterwards. Key to all of these improvements is the need to include those with mobility impairments in the planning and execution of fire evacuations and to facilitate their ability for self-evacuation as much as is practicable. The results of this study led to guidance on evacuation planning and procedures, the use of existing elevators for evacuation of people with mobility impairments, and the use of occupant evacuation elevators.
http://ift.tt/2oGmnLn
Source:Fire Safety Journal
Author(s): Kathryn Butler, Erica Kuligowski, Susanne Furman, Richard Peacock
Since the tragic loss of life in the World Trade Center disaster, efforts have refocused on the provision of safe and efficient evacuation procedures, especially for occupants who cannot negotiate exit stairs without assistance. Several evacuation options have been designed specifically for people with mobility impairments, including occupant evacuation elevators (OEEs). Face-to-face interviews were conducted with 51 participants with mobility impairments working in buildings located in five major metropolitan areas within the U.S. The dual goals in this study were to gain an understanding of how building occupants with mobility impairments evacuate multi-story buildings during fire emergencies and to identify perspectives on the use of elevators during fire evacuations. Data analysis of interviews highlighted the benefits and concerns of study participants involving both typical building evacuation methods (i.e., emergency stair travel devices and areas of refuge), as well as evacuation methods using elevators. This study also highlights improvements that can be made to elevator systems, particularly OEEs, to reduce anxiety about fire evacuation and increase trust in the occupant evacuation elevator system via a variety of means, including education and consultation in preparation for the evacuation, information and attention to occupant needs while the evacuation is taking place, and two-way feedback and discussions afterwards. Key to all of these improvements is the need to include those with mobility impairments in the planning and execution of fire evacuations and to facilitate their ability for self-evacuation as much as is practicable. The results of this study led to guidance on evacuation planning and procedures, the use of existing elevators for evacuation of people with mobility impairments, and the use of occupant evacuation elevators.
http://ift.tt/2oGmnLn
Δευτέρα 24 Απριλίου 2017
IJERPH, Vol. 14, Pages 457: Designing Fit for Purpose Health and Social Services for Ageing Populations
Population ageing is occurring in all countries, regardless of the level of economic development. While the rising burden of chronic diseases and disabilities as a consequence of this demographic transition is well recognized, the increasing prevalence of geriatric syndromes as a public health issue is not as well recognized. Recently the World Health Organization’s World Health and Ageing Report emphasized functional ability as an important outcome for aging populations, highlighting the concept of raising intrinsic capacity throughout the life course. The complementary perspective is the prevention of frailty, which has physical, cognitive, social and psychological dimensions. Therefore, services for older people should encompass medical as well as social components. The need and evolution for a transition in health and social services in Hong Kong, a special administrative region of China which has a population with the world’s highest life expectancy, is presented as an example of how one developed economy attempts to meet the challenges of population ageing. There is a need to shift to integrated care in the community instead of specialty dominated hospital care, and to establish regular activities in the community to adopt and maintain a lifestyle that reduces frailty and disability (or promotes intrinsic capacity). A top down approach with financial incentives, together with public education to help drive policy changes, are key drivers of change. It is expected that there will be much heterogeneity between different countries in terms of barriers and facilitators, such that each country needs to document their needs and design appropriate services.
http://ift.tt/2pfT8Tk
http://ift.tt/2pfT8Tk
IJERPH, Vol. 14, Pages 455: Exclusive Breastfeeding Practice and Its Association among Mothers of under 5 Children in Kwango District, DR Congo
The benefit of the breastfeeding has been well-established. In comparison to partial breast feeding, exclusive breastfeeding has even more benefits. The aim of this study was to identify the factors associated with breastfeeding exclusivity during the first 6 months of life in order to better target public health interventions in this community towards healthier infant nutrition and address child mortality in this population. A cross-sectional survey among 1145 random households was conducted in the Kwango district of the Democratic Republic of the Congo (DRC) during 2 November 2015 to 13 November 2015. Women of reproductive age from 15–49 years and having less than 5 years old child were selected for the study. Chi-squared test and bivariate and multivariate analyses were performed using SPSS. A major finding of this study is 49.2% of the mothers are exclusively breastfeeding their children, and marital status, literacy, place of delivery, knowledge of exclusive breastfeeding and access to radio are the key indicators for exclusive breastfeeding. Exclusive breastfeeding rate is almost equivalent to the national prevalence rate for the DRC. Providing adequate knowledge to raise awareness of exclusive breast feeding and increase involvement of health care providers in enhancing knowledge through antenatal care and during delivery and postnatal care will be the best approaches to increase exclusive breastfeeding practice.
http://ift.tt/2oGsIXQ
http://ift.tt/2oGsIXQ
IJERPH, Vol. 14, Pages 454: The Effects of Taekwondo Training on Peripheral Neuroplasticity-Related Growth Factors, Cerebral Blood Flow Velocity, and Cognitive Functions in Healthy Children: A Randomized Controlled Trial
Although regular Taekwondo (TKD) training has been reported to be effective for improving cognitive function in children, the mechanism underlying this improvement remains unclear. The purpose of the present study was to observe changes in neuroplasticity-related growth factors in the blood, assess cerebral blood flow velocity, and verify the resulting changes in children’s cognitive function after TKD training. Thirty healthy elementary school students were randomly assigned to control (n = 15) and TKD (n = 15) groups. The TKD training was conducted for 60 min at a rating of perceived exertion (RPE) of 11–15, 5 times per week, for 16 weeks. Brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and insulin-like growth factor-1 (IGF-1) levels were measured by blood sampling before and after the training, and the cerebral blood flow velocities (peak systolic [MCAs], end diastolic [MCAd], mean cerebral blood flow velocities [MCAm], and pulsatility index [PI]) of the middle cerebral artery (MCA) were measured using Doppler ultrasonography. For cognitive function assessment, Stroop Color and Word Tests (Word, Color, and Color-Word) were administered along with other measurements. The serum BDNF, VEGF, and IGF-1 levels and the Color-Word test scores among the sub-factors of the Stroop Color and Word Test scores were significantly higher in the TKD group after the intervention (p < 0.05). On the other hand, no statistically significant differences were found in any factors related to cerebral blood flow velocities, or in the Word test and Color test scores (p > 0.05). Thus, 16-week TKD training did not significantly affect cerebral blood flow velocities, but the training may have been effective in increasing children’s cognitive function by inducing an increase in the levels of neuroplasticity-related growth factors.
http://ift.tt/2oqeZZn
http://ift.tt/2oqeZZn
Associations between persistent organic pollutants, type 2 diabetes, diabetic nephropathy and mortality
Objective
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Relationships were examined between persistent organic pollutants (POPs) and incident type 2 diabetes, end-stage renal disease (ESRD) and mortality.
MethodsIn a nested case–control study, 300 persons without diabetes had baseline examinations between 1969 and 1974; 149 developed diabetes (cases) and 151 remained non-diabetic (controls) during 8.0 and 23.1 years of follow-up, respectively. POPs were measured at baseline. ORs for diabetes were computed by logistic regression analysis. The cases were followed from diabetes onset to ESRD, death or 2013. HRs for ESRD and mortality were computed by cause-specific hazard models. Patterns of association were explored using principal components analysis.
ResultsPCB151 increased the odds for incident diabetes, whereas hexachlorobenzene (HCB) was protective after adjusting for age, sex, body mass index, sample storage characteristics, glucose and lipid levels. Associations between incident diabetes and polychlorinatedbiphenyl (PCB) or persistent pesticide (PST) components were mostly positive but non-significant. Among the cases, 29 developed ESRD and 48 died without ESRD. PCB28, PCB49 and PCB44 increased the risk of ESRD after adjusting for baseline demographic and clinical characteristics. Several PCBs and PSTs increased the risk of death without ESRD. The principal components analysis identified PCBs with low-chlorine load positively associated with ESRD and death without ESRD, and several PSTs associated with death without ESRD.
ConclusionsMost POPs were positively but not significantly associated with incident diabetes. PCB151 was significantly predictive and HCB was significantly protective for diabetes. Among participants with diabetes, low-chlorine PCBs increase the risk of ESRD and death without ESRD, whereas several PSTs predict death without ESRD.
http://ift.tt/2q7ARF5
Mortality from cancer and other causes among Italian chrysotile asbestos miners
Objective
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To investigate the long-term mortality of a cohort of Italian asbestos miners.
MethodsThe cohort included 1056 men employed in a chrysotile mine between 1930 and 1990, who were followed up during 1946–2014, for a total of 37 471 person-years of observation. Expected deaths and SMRs were computed using national and local (after 1980, when available) reference.
ResultsA total of 294 (27.8%) subjects were alive and at the end of follow-up, 722 (68.4%) were dead and 40 (3.8%) were lost to follow-up. The SMR for overall mortality was 1.35 (95%CI 1.25 to 1.45). The SMR for pleural cancer, based on seven observed deaths, was 5.54 (95% CI 2.22 to 11.4) and related to time since first exposure, but not to duration of employment, cumulative exposure or time since last exposure. The SMR for lung cancer was 1.16 (95% CI 0.87 to 1.52; 53 observed deaths), with no excess among workers with cumulative exposure below 100 fibre/mL-years (SMR 0.82; 95% CI 0.44 to 1.40).
ConclusionsThe update of the follow-up of this cohort confirmed an increased mortality from pleural cancer mortality in miners exposed to chrysotile and a lack of significant increase in lung cancer mortality.
http://ift.tt/2ptbxNG
IJERPH, Vol. 14, Pages 453: Fat Mass Is Positively Associated with Estimated Hip Bone Strength among Chinese Men Aged 50 Years and above with Low Levels of Lean Mass
This study investigated the relationships of fat mass (FM) and lean mass (LM) with estimated hip bone strength in Chinese men aged 50–80 years (median value: 62.0 years). A cross-sectional study including 889 men was conducted in Guangzhou, China. Body composition and hip bone parameters were generated by dual-energy X-ray absorptiometry (DXA). The relationships of the LM index (LMI) and the FM index (FMI) with bone phenotypes were detected by generalised additive models and multiple linear regression. The associations between the FMI and the bone variables in LMI tertiles were further analysed. The FMI possessed a linear relationship with greater estimated hip bone strength after adjustment for the potential confounders (p < 0.05). Linear relationships were also observed for the LMI with most bone phenotypes, except for the cross-sectional area (p < 0.05). The contribution of the LMI (4.0%–12.8%) was greater than that of the FMI (2.0%–5.7%). The associations between the FMI and bone phenotypes became weaker after controlling for LMI. Further analyses showed that estimated bone strength ascended with FMI in the lowest LMI tertile (p < 0.05), but not in the subgroups with a higher LMI. This study suggested that LM played a critical role in bone health in middle-aged and elderly Chinese men, and that the maintenance of adequate FM could help to promote bone acquisition in relatively thin men.
http://ift.tt/2pVCczk
http://ift.tt/2pVCczk
Κυριακή 23 Απριλίου 2017
IJERPH, Vol. 14, Pages 452: Breast Cancer Screening Programmes across the WHO European Region: Differences among Countries Based on National Income Level
Breast cancer (BC) is the most frequent tumour affecting women all over the world. In low- and middle-income countries, where its incidence is expected to rise further, BC seems set to become a public health emergency. The aim of the present study is to provide a systematic review of current BC screening programmes in WHO European Region to identify possible patterns. Multiple correspondence analysis was performed to evaluate the association among: measures of occurrence; GNI level; type of BC screening programme; organization of public information and awareness campaigns regarding primary prevention of modifiable risk factors; type of BC screening services; year of screening institution; screening coverage and data quality. A key difference between High Income (HI) and Low and Middle Income (LMI) States, emerging from the present data, is that in the former screening programmes are well organized, with approved screening centres, the presence of mobile units to increase coverage, the offer of screening tests free of charge; the fairly high quality of occurrence data based on high-quality sources, and the adoption of accurate methods to estimate incidence and mortality. In conclusion, the governments of LMI countries should allocate sufficient resources to increase screening participation and they should improve the accuracy of incidence and mortality rates.
http://ift.tt/2p5hQ6U
http://ift.tt/2p5hQ6U
Σάββατο 22 Απριλίου 2017
Modeling flame extinction and reignition in large eddy simulations with fast chemistry
Publication date: June 2017
Source:Fire Safety Journal, Volume 90
Author(s): J.P. White, S. Vilfayeau, A.W. Marshall, A. Trouvé, R.J. McDermott
This work seeks to support the validation of large eddy simulation models used to simulate fire suppression. The emphasis in the present study is on the prediction of flame extinction and the prevention of spurious reignition using a fast chemistry, mixing-controlled combustion model applicable to realistic fire scenarios of engineering interest. The configuration provides a buoyant, turbulent methane diffusion flame within a controlled co-flowing oxidizer. The oxidizer allows for the supply of a mixture of air and nitrogen, including conditions for which oxygen-dilution in the oxidizer leads to flame extinction. Measurements to support model validation include local profiles of thermocouple temperature and oxygen mole fraction, global combustion efficiency, and the limiting oxygen index. The present study evaluates the performance of critical flame temperature based extinction and reignition models using the Fire Dynamics Simulator, an open-source fire dynamics solver. Alternate model cases are explored, each offering a unique treatment of extinction and reignition. Comparisons between simulated results and experimental measurements are used to evaluate the capability of these models to accurately describe flame extinction. Of the considered cases, those that include provisions to prevent spurious reignition show excellent agreement with measured data, whereas a baseline case lacking explicit reignition treatment fails to predict extinction.
http://ift.tt/2p6tD78
Source:Fire Safety Journal, Volume 90
Author(s): J.P. White, S. Vilfayeau, A.W. Marshall, A. Trouvé, R.J. McDermott
This work seeks to support the validation of large eddy simulation models used to simulate fire suppression. The emphasis in the present study is on the prediction of flame extinction and the prevention of spurious reignition using a fast chemistry, mixing-controlled combustion model applicable to realistic fire scenarios of engineering interest. The configuration provides a buoyant, turbulent methane diffusion flame within a controlled co-flowing oxidizer. The oxidizer allows for the supply of a mixture of air and nitrogen, including conditions for which oxygen-dilution in the oxidizer leads to flame extinction. Measurements to support model validation include local profiles of thermocouple temperature and oxygen mole fraction, global combustion efficiency, and the limiting oxygen index. The present study evaluates the performance of critical flame temperature based extinction and reignition models using the Fire Dynamics Simulator, an open-source fire dynamics solver. Alternate model cases are explored, each offering a unique treatment of extinction and reignition. Comparisons between simulated results and experimental measurements are used to evaluate the capability of these models to accurately describe flame extinction. Of the considered cases, those that include provisions to prevent spurious reignition show excellent agreement with measured data, whereas a baseline case lacking explicit reignition treatment fails to predict extinction.
http://ift.tt/2p6tD78
Electrically controlled dynamic sprinkler activation: Computational assessment of potential efficiency
Publication date: Available online 21 April 2017
Source:Fire Safety Journal
Author(s): Leonid Tanklevskiy, Anna Tsoy, Alexander Snegirev
Electrically controlled dynamic sprinkler activation is the novel technology of managing large automatic fire suppression systems that offers considerable potential advantages over conventional (thermal) sprinkler activation. It is designed to reduce the sprinkler response time, to ensure sprinkler activation in case of high ceiling clearance, and it can also be used for dynamic group activation enabling flexible response to the actual fire pattern and preventing the fire spread beyond the area protected by the group. Since the practical experience of using the new sprinkler activation algorithms is yet to be elaborated, this work attempts computational evaluation of the group enforced activation efficiency. Fire suppression dynamics is compared for a growing fire source impacted by the automatic sprinkler systems of two types: with conventional (thermal) and new (group enforced) activation algorithms. The effects of ceiling clearance, water flow rates, spray refinement, and of the horizontal airflow are examined.
http://ift.tt/2ozwots
Source:Fire Safety Journal
Author(s): Leonid Tanklevskiy, Anna Tsoy, Alexander Snegirev
Electrically controlled dynamic sprinkler activation is the novel technology of managing large automatic fire suppression systems that offers considerable potential advantages over conventional (thermal) sprinkler activation. It is designed to reduce the sprinkler response time, to ensure sprinkler activation in case of high ceiling clearance, and it can also be used for dynamic group activation enabling flexible response to the actual fire pattern and preventing the fire spread beyond the area protected by the group. Since the practical experience of using the new sprinkler activation algorithms is yet to be elaborated, this work attempts computational evaluation of the group enforced activation efficiency. Fire suppression dynamics is compared for a growing fire source impacted by the automatic sprinkler systems of two types: with conventional (thermal) and new (group enforced) activation algorithms. The effects of ceiling clearance, water flow rates, spray refinement, and of the horizontal airflow are examined.
http://ift.tt/2ozwots
Auto-extinction of engineered timber: Application to compartment fires with exposed timber surfaces
Publication date: Available online 21 April 2017
Source:Fire Safety Journal
Author(s): Alastair I. Bartlett, Rory M. Hadden, Juan P. Hidalgo, Simón Santamaria, Felix Wiesner, Luke A. Bisby, Susan Deeny, Barbara Lane
A series of compartment fire tests with multiple exposed timber surfaces have been undertaken to explore the effect of exposed timber on the fire dynamics and the potential for auto-extinction. A test with exposed wall and ceiling achieved auto-extinction after approximately 21min. Firepoint theory is applied using temperature data at the charline, is shown to predict a mass loss rate dropping below the critical value at 20–21min, and thus is successful in predicting auto-extinction. Additional uncertainties caused by delamination are explored, and recommendations for the use of auto-extinction in design are given.
http://ift.tt/2p6cKJA
Source:Fire Safety Journal
Author(s): Alastair I. Bartlett, Rory M. Hadden, Juan P. Hidalgo, Simón Santamaria, Felix Wiesner, Luke A. Bisby, Susan Deeny, Barbara Lane
A series of compartment fire tests with multiple exposed timber surfaces have been undertaken to explore the effect of exposed timber on the fire dynamics and the potential for auto-extinction. A test with exposed wall and ceiling achieved auto-extinction after approximately 21min. Firepoint theory is applied using temperature data at the charline, is shown to predict a mass loss rate dropping below the critical value at 20–21min, and thus is successful in predicting auto-extinction. Additional uncertainties caused by delamination are explored, and recommendations for the use of auto-extinction in design are given.
http://ift.tt/2p6cKJA
IJERPH, Vol. 14, Pages 451: Job Strain and Casual Blood Pressure Distribution: Looking beyond the Adjusted Mean and Taking Gender, Age, and Use of Antihypertensives into Account. Results from ELSA-Brasil
Methodological issues are pointed to as the main sources of inconsistencies in studies about the association between job strain and blood pressure (BP)/hypertension. Our aim was to analyze the relationship between job strain and the whole BP distribution, as well as potential differences by gender, age, and use of antihypertensives. Additionally, we addressed issues relating to the operationalization of the exposure and outcome variables that influence the study of their inter-relations. We evaluated the baseline date of 12,038 participants enrolled in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) (2008–2010), a multicenter cohort study of 35–74-year-old civil servants. Job strain was assessed by the Demand-Control-Support Questionnaire. The distribution of casual BP by categories of job strain was compared by a combination of exploratory techniques. Participants were classified into three subgroups (normotensives, medicated hypertensives, and unmedicated hypertensives), and analyses were stratified by gender and age. The relationship between job strain and casual BP varied along the whole outcome distribution. Hypertensive participants had greater differences in casual BP by job strain category, especially medicated hypertensives. Differences in casual BP were also greater for systolic than for diastolic BP and for older participants. No differences were encountered by gender. The exclusion of participants susceptible to misclassification for the exposure and outcome variables increased the differences observed between the categories of low and high job strain. In conclusion, the relationship between job strain and casual BP varied along the whole outcome distribution and by use of antihypertensive drugs, age, and BP parameter evaluated. Misclassification for exposure and outcome variables should be considered in analyses of this topic.
http://ift.tt/2oTfZUt
http://ift.tt/2oTfZUt
Παρασκευή 21 Απριλίου 2017
IJERPH, Vol. 14, Pages 449: Associations between Temperature and Hospital Admissions for Subarachnoid Hemorrhage in Korea
The relationship between temperature and subarachnoid hemorrhage (SAH) is less studied than that between temperature and myocardial infarction or other cardiovascular diseases. This study investigated the association between daily temperature and risk of SAH by analyzing the hospital admission records of 111,316 SAH patients from 2004 to 2012 in Korea. A Poisson regression model was used to examine the association between temperature and daily SAH hospital admissions. To analyze data and identify vulnerable groups, we used the following subgroups: sex, age, insurance type, area (rural or urban), and different climate zones. We confirmed a markedly higher SAH risk only for people of low socioeconomic status in both hot and cold temperatures; the relative risk (RR) in the Medicaid group was significantly increased and ranged from 1.04 to 1.11 for cold temperatures and 1.10 to 1.11 for hot temperatures. For the National Health Insurance group, the RR was increased to 1.02 for the maximum temperature only. The increased risk for SAH was highest in the temperate zone. An increase above the heat threshold temperature and a decrease below the cold threshold temperature were correlated with an increased risk of SAH in susceptible populations and were associated with different lag effects and RRs.
http://ift.tt/2oxE9Af
http://ift.tt/2oxE9Af
IJERPH, Vol. 14, Pages 450: A National Study of Social Media, Television, Radio, and Internet Usage of Adults by Sexual Orientation and Smoking Status: Implications for Campaign Design
Background: Smoking rates among lesbian, gay, and bisexual (LGB) people significantly exceed that of heterosexuals. Media interventions are an important part of tobacco control efforts, but limited information is available on LGB people’s media use. Methods: A nationally representative sample of 12,900 U.S. adults completed an online questionnaire assessing media use, smoking status, and demographic information. Multivariable logistic regression was used to assess relationships between media use with sexual orientation and smoking status. Results: A total of 590 (4.6%) respondents identified as LGB, of which 29% were smokers. Regardless of sexual orientation and smoking status, the Internet was the most popular media channel used, followed by television and radio. LGB respondents had significantly greater odds of having accounts on social media websites, accessing Facebook daily, and being a frequent Internet user, compared to heterosexual respondents. Similar media use was found between smokers and non-smokers, but smokers had greater odds of being frequent television viewers and frequent Internet users, compared to non-smokers. Conclusions: Compared to heterosexuals, LGB respondents reported greater use of the Internet, especially social media. Media campaigns targeting LGB populations can maximize reach by utilizing social media alongside traditional media channels.
http://ift.tt/2pLLReY
http://ift.tt/2pLLReY
IJERPH, Vol. 14, Pages 448: Who Is Using Outdoor Fitness Equipment and How? The Case of Xihu Park
Outdoor fitness equipment (OFE) placed in public parks has the potential to encourage physical activity. However, little is known about OFE users and use patterns. This study employed onsite and video observations of OFE usage to describe user characteristics and patterns in Xihu Park. Results indicate that OFE in this park attracted considerable use, particularly in the early morning and late afternoon. During these peak-hour observations, approximately 12 users per hour used the OFE, with the majority being females and seniors. The triple arm stretch and air walker were the most popular stations. However, most OFE users interacted with less than three of the available six OFE stations. Furthermore, users spent an average of less than nine minutes on all OFE stations combined. While OFE equipment was well-used in this urban park, it appears users did not interact with OFE at rates to produce a sufficient bout or level of physical activity during their park visit. Further investigations of OFE are encouraged to determine their health impact.
http://ift.tt/2pKupVk
http://ift.tt/2pKupVk
Unmanaged heathland – A fire risk in subzero temperatures?
Publication date: June 2017
Source:Fire Safety Journal, Volume 90
Author(s): Torgrim Log, Gunnar Thuestad, Liv Guri Velle, Sanjay Kumar Khattri, Gisle Kleppe
Parameters leading to the severe Flatanger and Frøya (Norway) January 2014 subzero wildfires, respectively burning 15km2 and 10km2 Atlantic heathlands (dominated by heather, Calluna vulgaris) and destroying 64 structures, have been analyzed. Traditional heathland management, including anthropogenic fire regimes, had not been performed in these areas over the last 50+ years. As a result, the vegetation composition consisted of degenerated old and woody Calluna stands, bushes and shrubs, with high amounts of accumulated (live and dead) biomass. Adiabatically heated subzero temperature easterlies dried the Calluna stands. When ignited, the lack of snow cover and the strong winds resulted in rapid fire spread. Rugged terrain, few hours of daylight at 64.4°N and the lack of roads and manmade fire lanes made controlling the fires very challenging. Drying experiments were conducted to learn how quickly Calluna plants dry at 20°C and 50% relative humidity from rain-wet conditions. Based on the surprisingly rapid drying of the lower (dead) canopy, vapor pressures and diffusion theory, it is concluded that the Flatanger and Frøya Calluna stands represented a severe fire risk within two days of exposure to 50% relative humidity air at 0°C. Young and more vigorous plants in the building phase (6–15 years old), as well as freeze drought damaged (typically some dead small branches) old but still live plants, showed different drying characteristics and dried more slowly. When understanding how degenerated Calluna stands, from Portugal to the Arctic Circle, dry in the wintertime, warnings may be issued when appropriate. This paper may also serve as input to discussions regarding the several-thousand-year tradition of prescribed burning versus potential raging wildfires in unmanaged Calluna stands.
http://ift.tt/2oYkdZb
Source:Fire Safety Journal, Volume 90
Author(s): Torgrim Log, Gunnar Thuestad, Liv Guri Velle, Sanjay Kumar Khattri, Gisle Kleppe
Parameters leading to the severe Flatanger and Frøya (Norway) January 2014 subzero wildfires, respectively burning 15km2 and 10km2 Atlantic heathlands (dominated by heather, Calluna vulgaris) and destroying 64 structures, have been analyzed. Traditional heathland management, including anthropogenic fire regimes, had not been performed in these areas over the last 50+ years. As a result, the vegetation composition consisted of degenerated old and woody Calluna stands, bushes and shrubs, with high amounts of accumulated (live and dead) biomass. Adiabatically heated subzero temperature easterlies dried the Calluna stands. When ignited, the lack of snow cover and the strong winds resulted in rapid fire spread. Rugged terrain, few hours of daylight at 64.4°N and the lack of roads and manmade fire lanes made controlling the fires very challenging. Drying experiments were conducted to learn how quickly Calluna plants dry at 20°C and 50% relative humidity from rain-wet conditions. Based on the surprisingly rapid drying of the lower (dead) canopy, vapor pressures and diffusion theory, it is concluded that the Flatanger and Frøya Calluna stands represented a severe fire risk within two days of exposure to 50% relative humidity air at 0°C. Young and more vigorous plants in the building phase (6–15 years old), as well as freeze drought damaged (typically some dead small branches) old but still live plants, showed different drying characteristics and dried more slowly. When understanding how degenerated Calluna stands, from Portugal to the Arctic Circle, dry in the wintertime, warnings may be issued when appropriate. This paper may also serve as input to discussions regarding the several-thousand-year tradition of prescribed burning versus potential raging wildfires in unmanaged Calluna stands.
http://ift.tt/2oYkdZb
An experimental study on backdraught: The dependence on temperature
Publication date: Available online 21 April 2017
Source:Fire Safety Journal
Author(s): Chia Lung Wu, Ricky Carvel
This paper presents the results of a series of reduced scale experiments to investigate the temperature conditions leading to backdraught in a fire compartment (0.8m×0.4m×0.4m), using solid polypropylene pellets as the fuel. The factors of primary interest are the pre-burn time, before the fire becomes oxygen limited, the duration of door closure, and the temperature distribution in the compartment. It is shown that the temperature inside the compartment is crucial for the occurrence of backdraught. Above 350°C, backdraught by auto-ignition is possible. If a pilot spark is present, backdraught may occur at temperatures down to 300°C. It is shown that backdraught conditions can be achieved in the early stages of a fire as long as a suitable temperature is reached, at considerably lower temperatures than those generated during flashover. Further investigation on gas concentration is essential to understand the chemistry of backdraught combustion.
http://ift.tt/2obp7ox
Source:Fire Safety Journal
Author(s): Chia Lung Wu, Ricky Carvel
This paper presents the results of a series of reduced scale experiments to investigate the temperature conditions leading to backdraught in a fire compartment (0.8m×0.4m×0.4m), using solid polypropylene pellets as the fuel. The factors of primary interest are the pre-burn time, before the fire becomes oxygen limited, the duration of door closure, and the temperature distribution in the compartment. It is shown that the temperature inside the compartment is crucial for the occurrence of backdraught. Above 350°C, backdraught by auto-ignition is possible. If a pilot spark is present, backdraught may occur at temperatures down to 300°C. It is shown that backdraught conditions can be achieved in the early stages of a fire as long as a suitable temperature is reached, at considerably lower temperatures than those generated during flashover. Further investigation on gas concentration is essential to understand the chemistry of backdraught combustion.
http://ift.tt/2obp7ox
Using suppression and detection devices to steer CFD fire forecast simulations
Publication date: Available online 20 April 2017
Source:Fire Safety Journal
Author(s): Wolfram Jahn
Firefighters would greatly benefit from a technology based on predictive fire simulations, able to assist their decision making process. For those simulations to be useful, they need a certain degree of precision and resolution that can only be provided by CFD type fire models. But CFD simulations typically take large periods of time to complete, and their results would thus not be available in time to be of use during an emergency. Due to the high complexity of fire spread dynamics that arises from the interaction between solid and gas phase and the corresponding physical-chemical processes (e.g. pyrolysis), the spread of the fire cannot be predicted from first principles in real-time using contemporary computers, and has to be given as parameters to the model. Data can be incorporated into the model to characterise the fire, but only a limited range of measurements are recorded in current buildings. While it might be possible that buildings of the future incorporate a higher density of sensors than contemporary buildings, it is likely that emergency response systems will have access only to conventional data such as smoke detectors and sprinkler activation time for the foreseeable future. In this study the use of conventional detection and suppression devices for the estimation of fire characteristics by means of an inverse modelling framework is explored. Additionally to the growth rate of the fire, the location of the fire origin is successfully estimated. Inverse CFD modelling and tangent linearisation is used to assimilate the data. The nature of the incoming data is consistent with current detection and suppression devices, in such that only a time of activation is recorded and fed into the model. It is shown that the growth rate of the fire and the location of its origin can be correctly and efficiently estimated using sprinkler and smoke detector activation time only. It is further shown that the estimated spread rate is not sensitive to fire origin location.
http://ift.tt/2oYeAdu
Source:Fire Safety Journal
Author(s): Wolfram Jahn
Firefighters would greatly benefit from a technology based on predictive fire simulations, able to assist their decision making process. For those simulations to be useful, they need a certain degree of precision and resolution that can only be provided by CFD type fire models. But CFD simulations typically take large periods of time to complete, and their results would thus not be available in time to be of use during an emergency. Due to the high complexity of fire spread dynamics that arises from the interaction between solid and gas phase and the corresponding physical-chemical processes (e.g. pyrolysis), the spread of the fire cannot be predicted from first principles in real-time using contemporary computers, and has to be given as parameters to the model. Data can be incorporated into the model to characterise the fire, but only a limited range of measurements are recorded in current buildings. While it might be possible that buildings of the future incorporate a higher density of sensors than contemporary buildings, it is likely that emergency response systems will have access only to conventional data such as smoke detectors and sprinkler activation time for the foreseeable future. In this study the use of conventional detection and suppression devices for the estimation of fire characteristics by means of an inverse modelling framework is explored. Additionally to the growth rate of the fire, the location of the fire origin is successfully estimated. Inverse CFD modelling and tangent linearisation is used to assimilate the data. The nature of the incoming data is consistent with current detection and suppression devices, in such that only a time of activation is recorded and fed into the model. It is shown that the growth rate of the fire and the location of its origin can be correctly and efficiently estimated using sprinkler and smoke detector activation time only. It is further shown that the estimated spread rate is not sensitive to fire origin location.
http://ift.tt/2oYeAdu
Energy distribution analysis in full-scale open floor plan enclosure fires
Publication date: Available online 20 April 2017
Source:Fire Safety Journal
Author(s): Cristian Maluk, Benjamin Linnan, Andy Wong, Juan P. Hidalgo, Jose L. Torero, Cecilia Abecassis-Empis, Adam Cowlard
Within a fast evolving built environment, understanding fire behaviour and the thermal exposure upon structural elements and systems is key for the continued provision of fire safe designs and solutions. Concepts of fire behaviour derived from research in enclosure fires has traditionally had a significant impact in general building design. At present, open floor plan enclosures are increasingly common – building design has drastically drifted away from traditional compartmentalisation. Nevertheless, the understanding of fire behaviour in open floor plan enclosures has not developed concurrently. The compartment fire framework, first conceived for under-ventilated fires in cubic compartments, has remained as standard practice. Although energy conservation within the enclosure was the basis for the current compartment fire framework that defines under-ventilated enclosure fires, little effort has been carried towards understanding the distribution of energy in design frameworks conceived for open floor plan enclosure fires. The work presented herein describes an analysis of the energy distribution established within an experimental full-scale open floor plan enclosure subjected to different fire modes and ventilation conditions. The results aim to enable the designer to estimate the fraction of the total energy released during a fire noteworthy to structural performance.
http://ift.tt/2obnE1k
Source:Fire Safety Journal
Author(s): Cristian Maluk, Benjamin Linnan, Andy Wong, Juan P. Hidalgo, Jose L. Torero, Cecilia Abecassis-Empis, Adam Cowlard
Within a fast evolving built environment, understanding fire behaviour and the thermal exposure upon structural elements and systems is key for the continued provision of fire safe designs and solutions. Concepts of fire behaviour derived from research in enclosure fires has traditionally had a significant impact in general building design. At present, open floor plan enclosures are increasingly common – building design has drastically drifted away from traditional compartmentalisation. Nevertheless, the understanding of fire behaviour in open floor plan enclosures has not developed concurrently. The compartment fire framework, first conceived for under-ventilated fires in cubic compartments, has remained as standard practice. Although energy conservation within the enclosure was the basis for the current compartment fire framework that defines under-ventilated enclosure fires, little effort has been carried towards understanding the distribution of energy in design frameworks conceived for open floor plan enclosure fires. The work presented herein describes an analysis of the energy distribution established within an experimental full-scale open floor plan enclosure subjected to different fire modes and ventilation conditions. The results aim to enable the designer to estimate the fraction of the total energy released during a fire noteworthy to structural performance.
http://ift.tt/2obnE1k
IJERPH, Vol. 14, Pages 437: Association between Serum Selenium Concentrations and Levels of Proinflammatory and Profibrotic Cytokines—Interleukin-6 and Growth Differentiation Factor-15, in Patients with Alcoholic Liver Cirrhosis
According to some authors, serum selenium levels are strongly associated with the severity of liver diseases, including liver cirrhosis. The aim of this study was to determine the relationship between the concentration of selenium and pro-inflammatory and profibrotic cytokines—interleukin-6 (IL-6) and growth differentiation factor 15 (GDF-15) in patients with alcoholic liver cirrhosis. The parameters studied were determined in the serum of 99 patients with alcoholic liver cirrhosis divided based on the severity of disease according to the Child-Turcotte-Pugh criteria. In patients with liver cirrhosis, the serum selenium concentration was statistically lower, whereas serum IL-6 and GDF-15 concentrations were higher than those in the control group. Moreover, the concentration of selenium negatively correlated with the levels of GDF-15 and IL-6. The above results may indicate a role of selenium deficiency in the pathogenesis and progression of alcoholic liver disease.
http://ift.tt/2osWY8z
http://ift.tt/2osWY8z
IJERPH, Vol. 14, Pages 447: Environmental Tobacco Smoke Exposure and Smoke-Free Rules in Homes among Socially-Disadvantaged Populations in Poland
This study aims to examine the prevalence of exposure to environmental tobacco smoke (ETS) in homes among socially-disadvantaged populations in Poland, along with the prevalence and correlates of voluntary implementation of smoke-free home rules. Data concerning 1617 respondents from a cross-sectional study completed in the Piotrkowski District were used, which was part of the “Reducing Social Inequalities in Health” program. Overall, 19.4% of the respondents declared exposure to ETS at home. In the non-smokers group, 15.5%, including 6.6% males and 18.3% females, were exposed to ETS in their place of residence (p < 0.0001). Complete smoke-free rules were adopted by 22.1% of the study participants. Two factors, smoker status and lack of ETS-associated health risk awareness, were found to be significantly associated with no adoption of total smoking bans at home. Socially-disadvantaged non-smokers, especially females from rural areas in Poland, still constitute a large population exposed to ETS in their homes—a challenge from the perspective of public health. Focused efforts are required to address social norms around exposing others to ETS.
http://ift.tt/2pl6qyS
http://ift.tt/2pl6qyS
Πέμπτη 20 Απριλίου 2017
IJERPH, Vol. 14, Pages 445: The Impact of Hyposalivation on Quality of Life (QoL) and Oral Health in the Aging Population of Al Madinah Al Munawarrah
Hyposalivation (HS) affects aging individuals by causing pain and discomfort in the oral cavity. The aim here was to determine the impact of hyposalivation and the saliva pH on the quality of life and caries status of geriatrics population. A total of 138 male outpatients attending the Taibah University College of Dentistry (TUCoD) dental clinic were included in the study. The saliva flow, pH, Quality of Life (QoL), and caries status were recorded. The QoL was measured using the Arabic version of the Oral Health Impact Profile-14 (OHIP-14), and the caries status was recorded using the Decayed, Missed, Filled Teeth (DMFT) index. The mean age was 67.5 years and 64% were classified as having hyposalivation. The older respondents tended to have a lower saliva flow and pH compared to their younger counterparts. There was a significant inverse association (p = 0.02) between the caries status and mean saliva flow rate. There was also a significant (p < 0.001) positive correlation between caries and the OHIP-14 scores (Spearman’s ρ = 0.293). The prevalence of hyposalivation was relatively high and there was an inverse relationship between the age, the saliva flow, and pH. Those with more caries reported significantly poor QoL.
http://ift.tt/2oqcBxm
http://ift.tt/2oqcBxm
IJERPH, Vol. 14, Pages 446: Prospective Analysis of the Influence of Sport and Educational Factors on the Prevalence and Initiation of Smoking in Older Adolescents from Croatia
The prevalence of smoking among Croatian adolescents is alarmingly high, but no previous study has prospectively examined the sport- and academic-factors associated with smoking and smoking initiation. This study aimed to prospectively examine the associations between scholastic (educational) achievement and sport factors and smoking in 16- to 18-year-old adolescents. This two-year prospective cohort study included 644 adolescents who were 16 years of age at baseline (46% females). Baseline testing was implemented at the beginning of the 3rd year of high school (September 2014) when participants were 16 years old. Follow-up testing was completed at the end of the fourth year of high school, which occurred 20 months later. The evaluated predictor variables were educational-achievement- and sport-related-factors. The outcome variables were (i) smoking at baseline; (ii) smoking at follow-up; and (iii) smoking initiation over the course of the study. We assessed the associations between predictors and outcomes using logistic regression models adjusted for age, gender, socioeconomic status, and conflict with parents. The educational variables were consistently associated with smoking, with lower grade-point-average (Baseline: odd ratio (OR): 2.01, 95% confidence interval (CI): 1.61–2.55; Follow-up: 1.59, 1.31–1.94), more frequent absence from school (Baseline: OR: 1.40, 95% CI: 1.19–1.69; Follow-up: 1.30, 1.08–1.58), and lower behavioral grades (Baseline: OR: 1.80, 95% CI: 1.10–2.89; Follow-up: 1.57, 1.03–2.41) in children who smoke. Adolescents who reported quitting sports were at greater odds of being smokers (Baseline: 2.07, 1.31–3.32; Follow-up: 1.66, 1.09–2.56). Sport competitive achievement at baseline was protective against smoking initiation during following two-year period (0.45, 0.21–0.91). While the influence of the educational variables on smoking initiation has been found to be established earlier; sport achievement was identified as a significant protective factor against initiating smoking in older adolescents. Results should be used in development of an anti-smoking preventive campaign in older adolescents.
http://ift.tt/2oOlFix
http://ift.tt/2oOlFix
IJERPH, Vol. 14, Pages 442: A Systematic Review: Costing and Financing of Water, Sanitation, and Hygiene (WASH) in Schools
Despite the success of recent efforts to increase access to improved water, sanitation, and hygiene (WASH) globally, approximately one-third of schools around the world still lack adequate WASH services. A lack of WASH in schools can lead to the spread of preventable disease and increase school absences, especially among women. Inadequate financing and budgeting has been named as a key barrier for integrating successful and sustainable WASH programs into school settings. For this reason, the purpose of this review is to describe the current knowledge around the costs of WASH components as well as financing models that could be applied to WASH in schools. Results show a lack of information around WASH costing, particularly around software elements as well as a lack of data overall for WASH in school settings as compared to community WASH. This review also identifies several key considerations when designing WASH budgets or selecting financing mechanisms. Findings may be used to advise future WASH in school programs.
http://ift.tt/2oTeZOx
http://ift.tt/2oTeZOx
IJERPH, Vol. 14, Pages 443: Acceptable Risk Analysis for Abrupt Environmental Pollution Accidents in Zhangjiakou City, China
Abrupt environmental pollution accidents cause considerable damage worldwide to the ecological environment, human health, and property. The concept of acceptable risk aims to answer whether or not a given environmental pollution risk exceeds a societally determined criterion. This paper presents a case study on acceptable environmental pollution risk conducted through a questionnaire survey carried out between August and October 2014 in five representative districts and two counties of Zhangjiakou City, Hebei Province, China. Here, environmental risk primarily arises from accidental water pollution, accidental air pollution, and tailings dam failure. Based on 870 valid questionnaires, demographic and regional differences in public attitudes towards abrupt environmental pollution risks were analyzed, and risk acceptance impact factors determined. The results showed females, people between 21–40 years of age, people with higher levels of education, public servants, and people with higher income had lower risk tolerance. People with lower perceived risk, low-level risk knowledge, high-level familiarity and satisfaction with environmental management, and without experience of environmental accidents had higher risk tolerance. Multiple logistic regression analysis indicated that public satisfaction with environmental management was the most significant factor in risk acceptance, followed by perceived risk of abrupt air pollution, occupation, perceived risk of tailings dam failure, and sex. These findings should be helpful to local decision-makers concerned with environmental risk management (e.g., selecting target groups for effective risk communication) in the context of abrupt environmental accidents.
http://ift.tt/2ouqmuj
http://ift.tt/2ouqmuj
IJERPH, Vol. 14, Pages 441: Water Access, Sanitation, and Hygiene Conditions and Health Outcomes among Two Settlement Types in Rural Far North Cameroon
The Far North region in Cameroon has been more heavily impacted by cholera than any other region over the past decade, but very little has been done to study the drivers of waterborne diseases in the region. We investigated the relationship between water, sanitation, and hygiene (WASH) parameters, microbial and antibiotic resistance (AR) contamination levels in drinking water, and health outcomes using health survey and molecular analysis during June and July of 2014 in two settlement types (agro-pastoralist villages and transhumant pastoralist camps). Quantitative polymerase chain reaction was used to determine fecal contamination sources, enteric pathogens, and antibiotic resistance genes. Ruminant-associated fecal contamination was widespread in both settlement types (81.2%), with human-associated contamination detected in 21.7% of the samples. Salmonella spp. (59.4%) and Shiga toxin-producing E. coli (stx1 44.9% and stx2 31.9%) were detected across all samples. Tetracycline resistance was found only in village samples. A significant difference in diarrheal incidence within the past 28 days among young children was found between camps (31.3%) and villages (0.0%). Our findings suggest that water contamination may play an important role in contributing to gastrointestinal illness, supporting the need for future research and public health intervention to reduce gastrointestinal illness in the area.
http://ift.tt/2opQ4B5
http://ift.tt/2opQ4B5
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