230 research outputs found
Effects of Boundary Conditions on Single-File Pedestrian Flow
In this paper we investigate effects of boundary conditions on one
dimensional pedestrian flow which involves purely longitudinal interactions.
Qualitatively, stop-and-go waves are observed under closed boundary condition
and dissolve when the boundary is open. To get more detailed information the
fundamental diagrams of the open and closed systems are compared using
Voronoi-based measurement method. Higher maximal specific flow is observed from
the pedestrian movement at open boundary condition
An Upper Limit to Microwave Pulse Emission at the Onset of a Supernova
This paper reports an upper limit at 10 GHz of 4 x 10^(43) erg in a 40 MHz bandwidth for the microwave pulse emission at the onset of an optically observed supernova
A Search for Isolated Microwave Pulses from the Perseus Cluster of Galaxies
The paper describes a search for prompt
microwave emissions from supernovae in the central
region of the Perseus cluster of galaxies, using a
coincidence technique involving five tracking radiometers
located at widely spaced sites. No coincidences
were found between January and December, 1973, and no supernovae were reported during this period
from the optical surveys, in that region of sky
The Fundamental Diagram of Pedestrian Movement Revisited
The empirical relation between density and velocity of pedestrian movement is
not completely analyzed, particularly with regard to the `microscopic' causes
which determine the relation at medium and high densities. The simplest system
for the investigation of this dependency is the normal movement of pedestrians
along a line (single-file movement). This article presents experimental results
for this system under laboratory conditions and discusses the following
observations: The data show a linear relation between the velocity and the
inverse of the density, which can be regarded as the required length of one
pedestrian to move. Furthermore we compare the results for the single-file
movement with literature data for the movement in a plane. This comparison
shows an unexpected conformance between the fundamental diagrams, indicating
that lateral interference has negligible influence on the velocity-density
relation at the density domain . In addition we test a
procedure for automatic recording of pedestrian flow characteristics. We
present preliminary results on measurement range and accuracy of this method.Comment: 13 pages, 9 figure
Enhanced empirical data for the fundamental diagram and the flow through bottlenecks
In recent years, several approaches for modelling pedestrian dynamics have
been proposed and applied e.g. for design of egress routes. However, so far not
much attention has been paid to their 'quantitative' validation. This
unsatisfactory situation belongs amongst others on the uncertain and
contradictory experimental data base. The fundamental diagram, i.e. the
density-dependence of the flow or velocity, is probably the most important
relation as it connects the basic parameter to describe the dynamic of crowds.
But specifications in different handbooks as well as experimental measurements
differ considerably. The same is true for the bottleneck flow. After a
comprehensive review of the experimental data base we give an survey of a
research project, including experiments with up to 250 persons performed under
well controlled laboratory conditions. The trajectories of each person are
measured in high precision to analyze the fundamental diagram and the flow
through bottlenecks. The trajectories allow to study how the way of measurement
influences the resulting relations. Surprisingly we found large deviation
amongst the methods. These may be responsible for the deviation in the
literature mentioned above. The results are of particular importance for the
comparison of experimental data gained in different contexts and for the
validation of models.Comment: A contribution to: Pedestrian and Evacuation Dynamics 2008 (Springer)
12 pages, 7 figure
Transportation research needs and issues for Chinese agriculture
Interprovincial circulation of grain and wholesale markets in China / Wu Shuo -- Inter-state/province grain transportation in the U.S. and China / Tenpao Lee, Robert J. Hauser, Stanley R. Thompson, and Barbara J. Hrutka -- Methodology and data systems for study of transportation / Won W. Koo and Jerry Fruin -- An application of a spatial equilibrium model to analyze the impact on China's trade of a policy change / Shwu-Eng H. Webb, Catherine K. Halbrendt, Rajaram Gana, and Francis Tuan -- Possible Joint Chinese and U.S. grain transportation and distribution research opportunities / Roland R. Robinson and Donald W. Larson -- Transportation research needs and issues for Chinese agriculture: discussion of session presentations / Dale G. Anderso
Inflammatory Response of Monocytes to Ambient Particles Varies by Highway Proximity
Epidemiological studies have demonstrated associations of chronic respiratory disease with near-roadway pollutant exposure, effects that were independent of those of regional air pollutants. However, there has been limited study of the potential mechanisms for near-roadway effects. Therefore, we examined the in vitro effect of respirable particulate matter (PM) collected adjacent to a major Los Angeles freeway and at an urban background location. PM was collected on filters during two consecutive 15-day periods. Oxidative stress and inflammatory response (intracellular reactive oxygen species [ROS], IL-1β, IL-6, IL-8, and TNF-α) to PM aqueous extract was assessed in THP-1 cells, a model for evaluating monocyte/macrophage lineage cell responses. The near-roadway PM induced statistically significantly higher levels of IL-6, IL-8, and TNF-α (P < 0.01) and a near significant increase in IL-1β (P = 0.06) but did not induce ROS activity (P = 0.17). The contrast between urban background and near-roadway PM-induced inflammatory cytokines was similar in magnitude to that corresponding to temporal differences between the two collection periods. PM-induced proinflammatory protein expression was attenuated by antioxidant pretreatment, and PM stimulation enhanced the activity of protein kinases, including extracellular signal-regulated kinase and c-Jun N-terminal kinase. Pretreatment of THP-1 cells with kinase inhibitors reduced PM-induced proinflammatory mediator expression. The proinflammatory response was also reduced by pretreatment with polymyxin B, suggesting a role for endotoxin. However, the patterns of PM-induced protein kinase response and the attenuation of inflammatory responses by antioxidant or polymyxin B pretreatment did not vary between near-roadway and urban background locations. We conclude that near-roadway PM produced greater inflammatory response than urban background PM, a finding consistent with emerging epidemiologic findings, but these differences were not explained by PM endotoxin content or by MAPK pathways. Nevertheless, THP-1 cells may be a model for the development of biologically relevant metrics of long-term spatial variation in exposure for study of chronic disease
BounceBack™ capsules for reduction of DOMS after eccentric exercise: a randomized, double-blind, placebo-controlled, crossover pilot study
<p>Abstract</p> <p>Background</p> <p>Delayed onset muscle soreness (DOMS) is muscle pain and discomfort experienced approximately one to three days after exercise. DOMS is thought to be a result of microscopic muscle fiber tears that occur more commonly after eccentric exercise rather than concentric exercise. This study sought to test the efficacy of a proprietary dietary supplement, BounceBack™, to alleviate the severity of DOMS after standardized eccentric exercise.</p> <p>Methods</p> <p>The study was a randomized, double-blind, placebo-controlled, crossover study. Ten healthy community-dwelling untrained subjects, ranging in age from 18–45 years, were enrolled. Mean differences within and between groups were assessed inferentially at each data collection time-point using t-tests for all outcome measures.</p> <p>Results</p> <p>In this controlled pilot study, intake of BounceBack™ capsules for 30 days resulted in a significant reduction in standardized measures of pain and tenderness post-eccentric exercise compared to the placebo group. There were trends towards reductions in plasma indicators of inflammation (high sensitivity C-reactive protein) and muscle damage (creatine phosphokinase and myoglobin).</p> <p>Conclusion</p> <p>BounceBack™ capsules were able to significantly reduce standardized measures of pain and tenderness at several post-eccentric exercise time points in comparison to placebo. The differences in the serological markers of DOMS, while not statistically significant, appear to support the clinical findings. The product appears to have a good safety profile and further study with a larger sample size is warranted based on the current results.</p
Spatial layout planning in sub-surface rail station design for effective fire evacuation
The London Underground network is a crucial part of the transportation system in one of only four ‘Alpha’ world cities. The other three – Paris, New York and Tokyo – also have such sub-surface railway transport systems that may benefit from this shape grammar station design process in a future research proposal. In London’s case, the passenger flow rates are the underlining factor in sizing infrastructure where passengers have access – it is therefore this criterion that provides the basis for the shape grammar formulation for the largest, oldest and one of the most complex underground systems in the world. The research aims to improve passenger fire evacuation times, with due cognisance of the growth of numbers using the system, and its present susceptibility to terrorist attacks taken into account. The proposed shape grammar approach will provide for generation of spatial layouts, based upon visual rules of shape recognition, replacement / union, their connectivity and spatial relationships. The paper concentrates on definition and implementation of novel shape grammar design rules that incorporate station planning design knowledge, and in particular also discusses designers’ fire risk assessment approach and related knowledge that is also needed to produce credible station design solutions. Development, to date, of the proposed artificially intelligent CAD environment is also described along with parallel theoretical research. The proposed CAD interface provides familiarity to the designer and avoids incompatibility issues regarding drawing exchange format between various software systems. The shape grammar layouts produced will be tested in SIMULEX, a commercially available evacuation package, and be compared against ‘traditionally’ designed layouts to demonstrate improvements of preliminary ‘reference’ designs, which follow the standard London Underground design process as a later stage of this research
Intelligent evacuation management systems: A review
Crowd and evacuation management have been active areas of research and study in the recent past. Various developments continue to take place in the process of efficient evacuation of crowds in mass gatherings. This article is intended to provide a review of intelligent evacuation management systems covering the aspects of crowd monitoring, crowd disaster prediction, evacuation modelling, and evacuation path guidelines. Soft computing approaches play a vital role in the design and deployment of intelligent evacuation applications pertaining to crowd control management. While the review deals with video and nonvideo based aspects of crowd monitoring and crowd disaster prediction, evacuation techniques are reviewed via the theme of soft computing, along with a brief review on the evacuation navigation path. We believe that this review will assist researchers in developing reliable automated evacuation systems that will help in ensuring the safety of the evacuees especially during emergency evacuation scenarios
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