562 research outputs found
Toward a Multi-stage Model of Hurricane Evacuation Decision: An Empirical Study of Hurricanes Katrina and Rita
This study extended previous research by testing the Protective Action Decision Model (PADM) on hurricane evacuation decisions during Hurricanes Katrina and Rita. An examination of this mediation model shows that a household’s evacuation decision, as predicted, is determined most directly by expected wind impacts and expected evacuation impediments. In turn, expected wind impacts and expected hydrological impacts are primarily determined by expected storm threat and expected rapid onset. Finally, expected storm threat, expected rapid onset, and expected evacuation impediments are determined by households’ personal characteristics, their reception of hurricane information, and their observations of social and environmental cues. These results are generally consistent with the PADM and reinforce the importance of testing multi-stage multi-equation models of hurricane evacuation
Predicting Residents’ Responses to the May 1-4, 2010, Boston Water Contamination Incident
This study examined 110 local residents’ warning sources, warning channels, warning receipt times, message content, risk perception, and behavioral responses (warning confirmation, and consumption of untreated tap water, boiled water, bottled water, and personally chlorinated water) during the May 1-4 2010 Boston water contamination incident. Most residents received warnings from peers and news media and these warnings mentioned 2.35 of five recommended elements of a warning message—most commonly the threat and the recommended protective action. TV was the most frequent channel for additional information, partly because it was the most frequent channel of routine information, but the Internet was also a common channel for additional information. Consumption of untreated tap water declined, consumption of personally chlorinated water remained negligible, and consumption of boiled water and bottled water increased during the incident. Warning receipt from an authority increased consumption of boiled water, whereas receipt of a less specific warning tended to increase consumption of bottled water. The distribution of warning times followed a logistic (S-shaped) distribution, with the largest increase taking place during prime TV news time (4-6pm). These results call attention to the need to increase the number of comprehensive warning response studies on rapid onset disasters to provide the basis for developing a comprehensive theory that can explain similarities and differences in responses to the full range of environmental hazards
Aberrant Amygdala–Frontal Cortex Connectivity During Perception Of Fearful Faces And At Rest In Generalized Social Anxiety Disorder
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97272/1/da22014.pd
Explicit solution for vibrating bar with viscous boundaries and internal damper
We investigate longitudinal vibrations of a bar subjected to viscous boundary
conditions at each end, and an internal damper at an arbitrary point along the
bar's length. The system is described by four independent parameters and
exhibits a variety of behaviors including rigid motion, super
stability/instability and zero damping. The solution is obtained by applying
the Laplace transform to the equation of motion and computing the Green's
function of the transformed problem. This leads to an unconventional
eigenvalue-like problem with the spectral variable in the boundary conditions.
The eigenmodes of the problem are necessarily complex-valued and are not
orthogonal in the usual inner product. Nonetheless, in generic cases we obtain
an explicit eigenmode expansion for the response of the bar to initial
conditions and external force. For some special values of parameters the system
of eigenmodes may become incomplete, or no non-trivial eigenmodes may exist at
all. We thoroughly analyze physical and mathematical reasons for this behavior
and explicitly identify the corresponding parameter values. In particular, when
no eigenmodes exist, we obtain closed form solutions. Theoretical analysis is
complemented by numerical simulations, and analytic solutions are compared to
computations using finite elements.Comment: 29 pages, 6 figure
Cytoskeletal Changes During Adhesion and Release: A Comparison of Human and Nonhuman Primate Platelets
The organization of cytoskeletal proteins in whole-mount adherent platelets from African green monkeys and normal human volunteers has been studied by SEM, high vacuum electron microscopy (HVEM) and conventional (120 kV) electron microscopy. We describe three distinct organizational zones, the Central Matrix, the Trabecular Zone and the Peripheral Web in spread platelets from both sources. The Central Matrix is an ill-defined superstructure of 80-100 Ă… filaments of short length which enshrouded the granules, dense bodies, mitochondria and elements of the open-channel and dense-tubular systems. The latter, identified through the use of peroxidase cytochemistry with the whole mounts, is an anastomosing network of elongate saccules having diameters of 600-1200 Ă…. The Trabecular Zone, which encircles the Central Matrix, contains 165, 80-100 and 30-50 Ă… filaments in an open lattice of irregular lattice spacing. The outermost region of the cells, the Peripheral Web, is comprised of 70 Ă… filaments organized in a honeycomb lattice with center to center spacing in the range 150-300 Ă…. This pattern for the spread cells is not consistently observed in cells during the early stages of adhesion; therefore, correlations of SEM and TEM observations are made for the various stages of adhesion/activation
The threshold elemental ratio of carbon and phosphorus of Daphnia magna and its connection to animal growth
The growth of animal consumers is afected by the balance of elements in their diet with the transition
between limitation by one element to another known as the threshold elemental ratio (TER). Precise
estimates of TERs with known levels of uncertainty have yet to be generated for most zooplankton
consumers. We determined the TER for carbon (C) and phosphorus (P) in for a common lake zooplankter,
Daphnia magna, using experimental measurements and theoretical considerations. Daphnia growth
responses to food C:P ratios across a relatively narrow range (80–350) generated an empirical estimate
of TERC:P of 155±14. While this TER matched our modelled estimate of TERC:P (155±16), it was lower
than previous estimates of this dietary transition point. No threshold was found when we examined
daphnid body C:N or C:P ratios in response to changing food C:P ratios, which indicates P-limitation at
even lower food C:P ratios. Our results provide strong evidence that D. magna is likely to experience
acute P-limitation when food C:P ratios exceed even relatively low ratios (~155). Our model further
demonstrated that while physiological adjustments may reduce the likelihood of P-limitation or reduce
its intensity, these changes in animal material processing would be accompanied by reduced maximum
growth rates
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How Do Perceptions of Risk Communicator Attributes Affect Emergency Response? An Examination of a Water Contamination Emergency in Boston, USA
A water main break that contaminated the Boston area\u27s water distribution system prompted a four-day “boil water” order. To understand risk communication during this incident, 600 randomly sampled residents were mailed questionnaires, yielding 110 valid responses. This article describes how perceptions of different social stakeholders influenced whether respondents complied with the Protective Action Recommendation—PAR (i.e., drank boiled water), took alternative protective actions (i.e., drank bottled water or/and self-chlorinated water), or ignored the threat (i.e., continued to drink untreated tap water). Respondents perceived technical authorities (i.e., water utility, public health, and emergency management) to be higher on three social influence attributes (hazard expertize, trustworthiness, and protection responsibility) than public (i.e., news media, elected officials) and private (i.e., self/family, peers, and personal physicians) intermediate sources. Furthermore, respondents were most likely to comply with the PAR if they perceived authorities and public intermediates to be high on all three attributes and if they had larger households and lower income. Contrarily, they were more likely to take alternative actions if they were younger and had higher levels of income, risk perception, and emergency preparedness. These results underscore the need for technical authorities to develop credibility with their potential audiences before a crisis occurs
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Observation of discrete, vortex light bullets
We report the first experimental observation of vortex light bullets that are discrete, spatiotemporal, solitary waves with orbital angular momentum. We analyze conditions for their existence and investigate their rich properties and dynamics. Vortex light bullets are excited in fiber arrays with spatially shaped femtosecond pulses and analyzed with a spatiotemporal cross correlator. Most importantly, we find that they have entirely new stability properties, being robust against considerable degrees of perturbation in a limited range of energies. All experimental findings are backed up by rigorous simulations, giving further insight into the rich dynamics of vortex light bullets
Assessment of vocal cord nodules: A case study in speech processing by using Hilbert-Huang Transform
Vocal cord nodules represent a pathological condition for which the growth of unnatural masses on vocal folds affects the patients. Among other effects, changes in the vocal cords' overall mass and stiffness alter their vibratory behaviour, thus changing the vocal emission generated by them. This causes dysphonia, i.e. abnormalities in the patients' voice, which can be analysed and inspected via audio signals. However, the evaluation of voice condition through speech processing is not a trivial task, as standard methods based on the Fourier Transform, fail to fit the non-stationary nature of vocal signals. In this study, four audio tracks, provided by a volunteer patient, whose vocal fold nodules have been surgically removed, were analysed using a relatively new technique: the Hilbert-Huang Transform (HHT) via Empirical Mode Decomposition (EMD); specifically, by using the CEEMDAN (Complete Ensemble EMD with Adaptive Noise) algorithm. This method has been applied here to speech signals, which were recorded before removal surgery and during convalescence, to investigate specific trends. Possibilities offered by the HHT are exposed, but also some limitations of decomposing the signals into so-called intrinsic mode functions (IMFs) are highlighted. The results of these preliminary studies are intended to be a basis for the development of new viable alternatives to the softwares currently used for the analysis and evaluation of pathological voice
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