1,075 research outputs found
Performance Assessment of Pressurized Stairs in High Rise Buildings
Research paper published in the journal Fire Technology, special issue on Smoke Control in Buildings and Tunnels.Pressurized stair cases are an important part of the fire safety strategy of
high rise buildings. Long egress times are compensated by creating safe environments
within egress staircases allowing the displacement time within those stairs as time
where occupants can be considered safe. The main mechanisms by which stairs are
‘‘made safe’’ are by guaranteeing structural protection of the enclosure and by elevating
the pressure within the stair to ensure that smoke cannot enter. Despite the critical
importance of this element of the fire safety strategy, the analysis and
implementation of these systems remain simplified. Simple models have been developed
using Bernoulli type formulations that account for static pressure and empirical
constants to calculate flows through doors and other leakage areas. Implementation
of these systems is even more simplified, consisting mainly of a direct feedback loop
that controls a fan output on the basis of a pressure measurement inside the stair.
The flow induced by the fan guarantees a minimum pressure. The pressure inside the
stair needs to be limited to enable doors to be open, thus pressure dampers are introduced
to release airflow in the event the pressure exceeds a specified maximum. Validation
of these methodologies was done in the 70s and 80s with very limited field
validation in real systems. This study presents an assessment of the performance of
pressurized staircases in six high rise buildings. All systems have been designed using
a similar methodology but implemented in different ways. In all cases the control
mechanism for the fan is a direct feedback loop from a single pressure sensor. The
results have been evaluated showing the limitations of the control system in the event
of multiple doors being opened and the limitations of the pressure release dampers
(as a response mechanism) if the pressure becomes unstable
The many positive impacts of participating in outreach activities on postgraduate students
Postgraduate students are excellent role models for school students, where their passion and energy play a vital role in engaging younger students and spreading enthusiasm and excitement about science. However, participating in outreach is not a one way activity for these postgraduate students. Through focus groups we show that the postgraduate students perceive that there are many benefits for themselves. These benefits are identified and discussed. This paper also contrasts the postgraduate with their undergraduate counterpart in terms of their contributions to engagement activities
Turbulent thermal diffusion in a multi-fan turbulence generator with the imposed mean temperature gradient
We studied experimentally the effect of turbulent thermal diffusion in a
multi-fan turbulence generator which produces a nearly homogeneous and
isotropic flow with a small mean velocity. Using Particle Image Velocimetry and
Image Processing techniques we showed that in a turbulent flow with an imposed
mean vertical temperature gradient (stably stratified flow) particles
accumulate in the regions with the mean temperature minimum. These experiments
detected the effect of turbulent thermal diffusion in a multi-fan turbulence
generator for relatively high Reynolds numbers. The experimental results are in
compliance with the results of the previous experimental studies of turbulent
thermal diffusion in oscillating grids turbulence (Buchholz et al. 2004;
Eidelman et al. 2004). We demonstrated that turbulent thermal diffusion is an
universal phenomenon. It occurs independently of the method of turbulence
generation, and the qualitative behavior of particle spatial distribution in
these very different turbulent flows is similar. Competition between turbulent
fluxes caused by turbulent thermal diffusion and turbulent diffusion determines
the formation of particle inhomogeneities.Comment: 9 pages, 9 figure, REVTEX4, Experiments in Fluids, in pres
The pharmaceutical use of permethrin: Sources and behavior during municipal sewage treatment
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2010 Springer Science+Business Media, LLC.Permethrin entered use in the 1970s as an insecticide in a wide range of applications, including agriculture, horticultural, and forestry, and has since been restricted. In the 21st century, the presence of permethrin in the aquatic environment has been attributed to its use as a human and veterinary pharmaceutical, in particular as a pedeculicide, in addition to other uses, such as a moth-proofing agent. However, as a consequence of its toxicity to fish, sources of permethrin and its fate and behavior during wastewater treatment are topics of concern. This study has established that high overall removal of permethrin (approximately 90%) was achieved during wastewater treatment and that this was strongly dependent on the extent of biological degradation in secondary treatment, with more limited subsequent removal in tertiary treatment processes. Sources of permethrin in the catchment matched well with measured values in crude sewage and indicated that domestic use accounted for more than half of the load to the treatment works. However, removal may not be consistent enough to achieve the environmental quality standards now being derived in many countries even where tertiary treatment processes are applied.United Utilities PL
Low computed tomography coronary artery calcium scores in familial longevity: the Leiden Longevity Study
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The use of phylogeny to interpret cross-cultural patterns in plant use and guide medicinal plant discovery: an example from Pterocarpus (Leguminosae)
The study of traditional knowledge of medicinal plants has led to discoveries that have helped combat diseases and improve healthcare. However, the development of quantitative measures that can assist our quest for new medicinal plants has not greatly advanced in recent years. Phylogenetic tools have entered many scientific fields in the last two decades to provide explanatory power, but have been overlooked in ethnomedicinal studies. Several studies show that medicinal properties are not randomly distributed in plant phylogenies, suggesting that phylogeny shapes ethnobotanical use. Nevertheless, empirical studies that explicitly combine ethnobotanical and phylogenetic information are scarce.In this study, we borrowed tools from community ecology phylogenetics to quantify significance of phylogenetic signal in medicinal properties in plants and identify nodes on phylogenies with high bioscreening potential. To do this, we produced an ethnomedicinal review from extensive literature research and a multi-locus phylogenetic hypothesis for the pantropical genus Pterocarpus (Leguminosae: Papilionoideae). We demonstrate that species used to treat a certain conditions, such as malaria, are significantly phylogenetically clumped and we highlight nodes in the phylogeny that are significantly overabundant in species used to treat certain conditions. These cross-cultural patterns in ethnomedicinal usage in Pterocarpus are interpreted in the light of phylogenetic relationships.This study provides techniques that enable the application of phylogenies in bioscreening, but also sheds light on the processes that shape cross-cultural ethnomedicinal patterns. This community phylogenetic approach demonstrates that similar ethnobotanical uses can arise in parallel in different areas where related plants are available. With a vast amount of ethnomedicinal and phylogenetic information available, we predict that this field, after further refinement of the techniques, will expand into similar research areas, such as pest management or the search for bioactive plant-based compounds
Reference materials for phase equilibrium studies. 2. Solid-liquid equilibria (IUPAC Technical Report)
This article is the second of three projected IUPAC Technical Reports on reference materials for phase equilibrium studies. The goal of this project was to select reference systems with critically evaluated property values for the verification of instruments and techniques used in phase equilibrium studies of mixtures. This report proposes seven systems for solid–liquid equilibrium studies, covering the four most common categories of binary mixtures: aqueous systems with organic solutes, aqueous systems with inorganic solutes, non-aqueous systems, and systems with low solubility. For each system, the available literature sources, accepted data, smoothing equations, and estimated uncertainties are given
Single pi+ Electroproduction on the Proton in the First and Second Resonance Regions at 0.25GeV^2 < Q^2 < 0.65GeV^2 Using CLAS
The ep -> e'pi^+n reaction was studied in the first and second nucleon
resonance regions in the 0.25 GeV^2 < Q^2 < 0.65 GeV^2 range using the CLAS
detector at Thomas Jefferson National Accelerator Facility. For the first time
the absolute cross sections were measured covering nearly the full angular
range in the hadronic center-of-mass frame. The structure functions sigma_TL,
sigma_TT and the linear combination sigma_T+epsilon*sigma_L were extracted by
fitting the phi-dependence of the measured cross sections, and were compared to
the MAID and Sato-Lee models.Comment: Accepted for publication in PR
Pyrethroid treatment of cattle for tsetse control: Reducing its impact on dung fauna
Background: African trypansomiases of humans and animals can be controlled by attacking the vectors,various species of tsetse fly. Treatment of cattle with pyrethroids to kill tsetse as they feed is the most cost-effective method. However, such treatments can contaminate cattle dung, thereby killing the fauna which disperse the dung and so play an important role in soil fertility. Hence there is a need to identify cost-effective methods of treating cattle with minimal impact on dung fauna.
Methodology/Principal Findings: We used dung beetles to field bioassay the levels of dung contamination following the use of spray and pour-on formulations of deltamethrin, applied to various parts of the body of cattle in Zimbabwe. Results suggested that dung was contaminated by contact with insecticide on the body surface as the cattle defecated, and by ingestion of insecticide as the cattle
licked themselves. Death of dung beetles was reduced to negligible levels by using only the spray and applying it to the legs and belly or legs alone, i.e., places where most tsetse feed.
Conclusion/Significance: The restricted applications suitable for minimising the impact on dung fauna have the collateral benefits of improving the economy and convenience of cattle treatments for tsetse control. The demonstration of collateral benefits is one of the surest ways of promoting environmentally friendly procedures
The effect of iterative model reconstruction on coronary artery calcium quantification
Coronary artery calcium (CAC) scoring with computed tomography (CT) is an established tool for quantifying calcified atherosclerotic plaque burden. Despite the widespread use of novel image reconstruction techniques in CT, the effect of iterative model reconstruction on CAC score remains unclear. We sought to assess the impact of iterative model based reconstruction (IMR) on coronary artery calcium quantification as compared to the standard filtered back projection (FBP) algorithm and hybrid iterative reconstruction (HIR). In addition, we aimed to simulate the impact of iterative reconstruction techniques on calcium scoring based risk stratification of a larger asymptomatic population. We studied 63 individuals who underwent CAC scoring. Images were reconstructed with FBP, HIR and IMR and CAC scores were measured. We estimated the cardiovascular risk reclassification rate of IMR versus HIR and FBP in a larger asymptomatic population (n = 504). The median CAC scores were 147.7 (IQR 9.6-582.9), 107.0 (IQR 5.9-526.6) and 115.1 (IQR 9.3-508.3) for FBP, HIR and IMR, respectively. The HIR and IMR resulted in lower CAC scores as compared to FBP (both p < 0.001), however there was no difference between HIR and IMR (p = 0.855). The CAC score decreased by 7.2 % in HIR and 7.3 % in IMR as compared to FBP, resulting in a risk reclassification rate of 2.4 % for both HIR and IMR. The utilization of IMR for CAC scoring reduces the measured calcium quantity. However, the CAC score based risk stratification demonstrated modest reclassification in IMR and HIR versus FBP
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