SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Risk analysis : an official publication of the Society for Risk Analysis

28

The devastating impact by Hurricane Sandy (2012) again showed New York City (NYC) is one of the most vulnerable cities to coastal flooding around the globe. The low-lying areas in NYC can be flooded by nor'easter storms and North Atlantic hurricanes. The few studies that have estimated potential flood damage for NYC base their damage estimates on only a single, or a few, possible flood events. The objective of this study is to assess the full distribution of hurricane flood risk in NYC. This is done by calculating potential flood damage with a flood damage model that uses many possible storms and surge heights as input. These storms are representative for the low-probability/high-impact flood hazard faced by the city. Exceedance probability-loss curves are constructed under different assumptions about the severity of flood damage. The estimated flood damage to buildings for NYC is between US$59 and 129 millions/year. The damage caused by a 1/100-year storm surge is within a range of US$2 bn-5 bn, while this is between US$5 bn and 11 bn for a 1/500-year storm surge. An analysis of flood risk in each of the five boroughs of NYC finds that Brooklyn and Queens are the most vulnerable to flooding. This study examines several uncertainties in the various steps of the risk analysis, which resulted in variations in flood damage estimations. These uncertainties include: the interpolation of flood depths; the use of different flood damage curves; and the influence of the spectra of characteristics of the simulated hurricanes.

Concepts: Atlantic Ocean, Storm, New York City, Tropical cyclone, Flood, Queens, Storm surge, Brooklyn

28

Previous research has shown that people err when making decisions aided by probability information. Surprisingly, there has been little exploration into the accuracy of decisions made based on many commonly used probabilistic display methods. Two experiments examined the ability of a comprehensive set of such methods to effectively communicate critical information to a decision maker and influence confidence in decision making. The second experiment investigated the performance of these methods under time pressure, a situational factor known to exacerbate judgmental errors. Ten commonly used graphical display methods were randomly assigned to participants. Across eight scenarios in which a probabilistic outcome was described, participants were asked questions regarding graph interpretation (e.g., mean) and made behavioral choices (i.e., act; do not act) based on the provided information indicated that decision-maker accuracy differed by graphical method; error bars and boxplots led to greatest mean estimation and behavioral choice accuracy whereas complementary cumulative probability distribution functions were associated with the highest probability estimation accuracy. Under time pressure, participant performance decreased when making behavioral choices.

Concepts: Decision making, Critical thinking, Statistics, Risk, Decision theory, Decision making software, Cumulative distribution function, Choice architecture

28

Crowd density is a key factor that influences the moving characteristics of a large group of people during a large-scale evacuation. In this article, the macro features of crowd flow and subsequent rescue strategies were considered, and a series of characteristic crowd densities that affect large-scale people movement, as well as the maximum bearing density when the crowd is extremely congested, were analyzed. On the basis of characteristic crowd densities, the queuing theory was applied to simulate crowd movement. Accordingly, the moving characteristics of the crowd and the effects of typical crowd density-which is viewed as the representation of the crowd’s arrival intensity in front of the evacuation passageways-on rescue strategies was studied. Furthermore, a “risk axle of crowd density” is proposed to determine the efficiency of rescue strategies in a large-scale evacuation, i.e., whether the rescue strategies are able to effectively maintain or improve evacuation efficiency. Finally, through some rational hypotheses for the value of evacuation risk, a three-dimensional distribution of the evacuation risk is established to illustrate the risk axle of crowd density. This work aims to make some macro, but original, analysis on the risk of large-scale crowd evacuation from the perspective of the efficiency of rescue strategies.

Concepts: Effect, Density, Sociology, Economics, Characteristic, Queueing theory

27

This study bridges a gap between public library and emergency management policy versus practice by examining the role of public libraries in the community resource network for disaster recovery. Specifically, this study identifies the opportunities and challenges for public libraries to fulfill their role as a FEMA-designated essential community organization and enhance community resilience. The results indicate there are several opportunities for libraries to enhance community resilience by offering technology resources and assistance; providing office, meeting, and community living room space; serving as the last redundant communication channel and a repository for community information and disaster narratives; and adapting or expanding services already offered to meet the changing needs of the community. However, libraries also face challenges in enhancing community resilience, including the temptation to overcommit library capacity and staff capability beyond the library mission and a lack of long-term disaster plans and collaboration with emergency managers and government officials. Implications for library and emergency management practice and crisis research are discussed.

Concepts: Public library, Library, Librarian

27

With the circulation of wild poliovirus (WPV) types 1 and 3 continuing more than a decade after the original goal of eradicating all three types of WPVs by 2000, policymakers consider many immunization options as they strive to stop transmission in the remaining endemic and outbreak areas and prevent reintroductions of live polioviruses into nonendemic areas. While polio vaccination choices may appear simple, our analysis of current options shows remarkable complexity. We offer important context for current and future polio vaccine decisions and policy analyses by developing decision trees that clearly identify potential options currently used by countries as they evaluate national polio vaccine choices. Based on a comprehensive review of the literature we (1) identify the current vaccination options that national health leaders consider for polio vaccination, (2) characterize current practices and factors that appear to influence national and international choices, and (3) assess the evidence of vaccine effectiveness considering sources of variability between countries and uncertainties associated with limitations of the data. With low numbers of cases occurring globally, the management of polio risks might seem like a relatively low priority, but stopping live poliovirus circulation requires making proactive and intentional choices to manage population immunity in the remaining endemic areas and to prevent reestablishment in nonendemic areas. Our analysis shows remarkable variability in the current national polio vaccine product choices and schedules, with combination vaccine options containing inactivated poliovirus vaccine and different formulations of oral poliovirus vaccine making choices increasingly difficult for national health leaders.

Concepts: Immune system, Vaccine, Vaccination, Poliomyelitis, Polio vaccine, Poliomyelitis eradication, OPV AIDS hypothesis, Poliovirus

26

Quantitative approaches to assessing exposure to, and associated risk from, benzene in mineral spirits solvent (MSS), used widely in parts washing and degreasing operations, have focused primarily on the respiratory pathway. The dermal contribution to total benzene uptake from such operations remains uncertain because measuring in vivo experimental dermal uptake of this volatile human carcinogen is difficult. Unprotected dermal uptake involves simultaneous sustained immersion events and transient splash/wipe events, each yielding residues subject to evaporation as well as dermal uptake. A two-process dermal exposure framework to assess dermal uptake to normal and damaged skin was applied to estimate potential daily dermal benzene dose (Dskin ) to workers who used historical or current formulations of recycled MSS in manual parts washers. Measures of evaporation and absorption of MSS dermally applied to human subjects were modeled to estimate in vivo dermal uptake of benzene in MSS. Uncertainty and interindividual variability in Dskin was characterized by Monte Carlo simulation, conditioned on uncertainty and/or variability estimated for each model input. Dermal exposures are estimated to average 33% of total (inhalation + dermal) benzene parts washing dose, with approximately equal predicted portions of dermal dose due to splash/wipe and to continuous contact with MSS. The estimated median (95th percentile) dermal and total daily benzene doses from parts washing are: 0.0069 (0.024) and 0.025 (0.18) mg/day using current, and 0.027 (0.085) and 0.098 (0.69) mg/day using historical, MSS solvents, respectively.

Concepts: Median, Benzene, Solvent, Monte Carlo, Approximation, Estimation, Carcinogen, Pi

25

Polycyclic aromatic hydrocarbons (PAHs) have been labeled contaminants of concern due to their carcinogenic potential, insufficient toxicological data, environmental ubiquity, and inconsistencies in the composition of environmental mixtures. The Environmental Protection Agency is reevaluating current methods for assessing the toxicity of PAHs, including the assumption of toxic additivity in mixtures. This study was aimed at testing mixture interactions through in vitro cell culture experimentation, and modeling the toxicity using quantitative structure-activity relationships (QSAR). Clone-9 rat liver cells were used to analyze cellular proliferation, viability, and genotoxicity of 15 PAHs in single doses and binary mixtures. Tests revealed that many mixtures have nonadditive toxicity, but display varying mixture effects depending on the mixture composition. Many mixtures displayed antagonism, similar to other published studies. QSARs were then developed using the genetic function approximation algorithm to predict toxic activity both in single PAH congeners and in binary mixtures. Effective concentrations inhibiting 50% of the cell populations were modeled, with R(2) = 0.90, 0.99, and 0.84, respectively. The QSAR mixture algorithms were then adjusted to account for the observed mixture interactions as well as the mixture composition (ratios) to assess the feasibility of QSARs for mixtures. Based on these results, toxic addition is improbable and therefore environmental PAH mixtures are likely to see nonadditive responses when complex interactions occur between components. Furthermore, QSAR may be a useful tool to help bridge these data gaps surrounding the assessment of human health risks that are associated with PAH exposures.

Concepts: Algorithm, Polycyclic aromatic hydrocarbon, Benzene, Toxicology, Aromaticity, Environmentalism, Naphthalene, Quantitative structure-activity relationship

25

Modeling the dependence between uncertainties in decision and risk analyses is an important part of the problem structuring process. We focus on situations where correlated uncertainties are discrete, and extend the concept of the copula-based approach for modeling correlated continuous uncertainties to the representation of correlated discrete uncertainties. This approach reduces the required number of probability assessments significantly compared to approaches requiring direct estimates of conditional probabilities. It also allows the use of multiple dependence measures, including product moment correlation, rank order correlation and tail dependence, and parametric families of copulas such as normal copulas, t-copulas, and Archimedean copulas. This approach can be extended to model the dependence between discrete and continuous uncertainties in the same event tree.

Concepts: Risk, Decision theory, Probability theory, Probability, Event, Conditional probability, Random variable, Probability space

24

Seasonal flu vaccination rates are low for U.S. adults, with significant disparities between African and white Americans. Risk perception is a significant predictor of vaccine behavior but the research on this construct has been flawed. This study addressed critical research questions to understand the differences between African and white Americans in the role of risk perception in flu vaccine behavior: (1) What is the dimensionality of risk perception and does it differ between the two races?  (2) Were risk perceptions of white and African-American populations different and how were sociodemographic characteristics related to risk for each group? (3) What is the relation between risk perception and flu vaccine behaviors for African Americans and whites? The sample, drawn from GfK’s Knowledge Panel, consisted of 838 whites and 819 African Americans. The survey instrument was developed from qualitative research. Measures of risk perception included cognitive and emotional measures of disease risk and risk of side effects from the vaccine. The online survey was conducted in March 2015. Results showed the importance of risk perception in the vaccine decision-making process for both racial groups. As expected, those who got the vaccine reported higher disease risk than those who did not. Separate cognitive and emotional factors did not materialize in this study but strong evidence was found to support the importance of considering disease risk as well as risk of the vaccine. There were significant racial differences in the way risk perception predicted behavior.

Concepts: Psychology, Vaccine, United States, Black people, Race, White American, African American, Racism

24

This research is designed to provide insight into the psychological (e.g., threat appraisal or coping appraisal) and other determinants (e.g., information quality judgments or demographics) of risk information seeking or avoidance in times of an acute risk, as part of the process of increasing public resilience through adherence to risk mitigating advice. Data were collected via telephone interviews. A specialized agency interviewed 1,000 Dutch citizens, randomly confronted with one of eight fictitious, but realistic, acute risk and emergency situations. Results indicate that information seeking in an acute situation is anticipated by a less elaborate set of predictors (age and risk perception) than information seeking in a nonacute situation (age and risk perception, as well as educational level and social norm). Although risk perception is a predictor for risk information seeking, its predictive value for acute-risk-related behavior, as one might have assumed based on theories such as protection motivation theory (PMT) or the extended parallel process model (EPPM), appears to be limited. Implications for risk communication are discussed.

Concepts: Psychology, Risk, Sociology, Educational psychology, Information, Behavior, Motivation, Human behavior