Is seat belt usage by front seat passengers related to seat belt usage by their drivers?

INTRODUCTION: Unrestrained drivers and passengers are involved in a significant amount of fatalities and injuries in motor-vehicle crashes in the United States. While the literature documents the effectiveness of seat belt usage in reducing crash outcomes, such as fatalities and the severity of injuries, there is a need to evaluate the impact of seat belt usage by drivers and passengers in their respective vehicles. These findings could help develop effective education and enforcement strategies to enhance occupant safety. METHOD: This paper summarizes a study comparing seat belt usage rates of drivers and passengers based on whether or not the driver uses a seat belt. Observational data from 50 sites in the state of Nevada over 3 years are used for analyses. The data are stratified based on the gender of the driver and passengers in the front seat of the vehicle and are based on area type (rural or urban). RESULTS: A comparison of the rates of seat belt usage across for the aggregated data and for various types of disaggregation and statistical analyses to compare the rates of seat belt use among passengers based on the use of seat belts by drivers confirms that when drivers use seat belts, their respective passengers are much more likely to use seat belts. Further, if drivers do not use seat belts, their passengers are not likely to use seat belts. This observation is comparable for male drivers and female drivers, and also for male passengers and female passengers. Further, there are no differences for combinations of the genders of the drivers and passenger (i.e., both male or female, or one male and one female). IMPACT ON INDUSTRY: These results suggest that education and enforcement strategies would benefit most by working toward increasing seat belt usage rates among drivers.     

Spatial distribution of dissolved Pb, Hg, Cd, Cu and As in the Bohai Sea

Characteristics of the spatial distribution of selected dissolved heavy metals were analyzed during large scale surveys from August 12 to 25,2003 in the Bohai Sea.Dissolved Pb was the only element with average concentrations higher than the grade-one sea water quality standard of China.The spatial distribution of dissolved Pb in surface water was similar to those of Cd,Cu and As,where the isopleths generally indicated decreasing values from the bays to the central areas.Only for Hg did the high concentrations not only appear in Liaodong Bay,Bohai Bay and Laizhou Bay,but also in the Central Area,viz.not only in inshore but also in offshore areas. Vertical distributions of dissolved Pb,Cd,Cu and As were largely uniform,while that of dissolved Hg increased with depth.We infer that the input of pollutants from land was the main influencing factor for the detected distribution patterns of dissolved heavy metals, followed by the dynamics of sea water,release from bottom sediments and biochemical processes.Comparing with historical data, average concentrations of dissolved heavy metals appear to decline in recent years.     

地球物理方法在地下水有机污染DNAPLs的调查与监测中的应用

地下水有机污染特别是重非水相液体(densenon-aqueousphaseliquids,缩写为DNAPLs)污染是当前国际上地下水污染控制的热点问题,而对DNAPLs的调查与监测也一直是近年来环境地球物理研究的热点。文章简述了DNAPLs的运移、分布规律和DNAPLs与周围土壤及岩石存在的物理性质差异,综述了地球物理方法在DNAPLs的调查与监测应用中的有效性,探讨了地球物理方法直接探测DNAPLs的可行性,并提出了展望。     

Landholder Profiling and Typologies for Natural Resource–Management Policy and Program Support: Potential and Constraints

The use of landholder typologies to aid the development, implementation, and monitoring natural-resource management (NRM) policies and programs has increased considerably during the past decade. This article explores the potential for using such typologies for a variety of NRM and rural and regional development applications. Review of typology use further suggests that there is potential to refine the way that typologies are developed and applied to better aid NRM, farming systems analyses, and rural and regional development. Before typologies will be adopted more widely, a number of theoretical and methodologic issues must be addressed. These include the following questions: (1) Which criteria and methods should or can be used to classify landholders? (2) How should studies across spatial and temporal scales be integrated? (3) How should multiple and single industry studies be integrated to gain the most value from research? We argue that quantitative research techniques are well suited to provide an underlying structure for landholder typologies, and qualitative research techniques are useful for developing understanding of the nature of variation within and between landholder types. We argued further that because of the potential utility and breadth for the application of landholder typologies, a nested set of landholder typologies could be developed that are coordinated at the national, regional, and local geographic levels, with repeated measures used to track the evolution with time of landholder practices, management values, and socioeconomic characteristics.     

地球物理环境与人类健康

阐述了地球物理环境的概念，以及原生物环境和次生物环境与人类健康之间的相互关系。文章指出，地球物理环境的存在及发展变化与人类的健康生存有密切的关系：由于现代生产活动所导致的的地球物理环境污染，破坏，已构成对人类健康的严重影响。文章呼吁，要加强对地球物理环境的保护，重视并开展这方面的有关研究，制订地球物理环境质量标准，切实保护好地球物理环境。     

Book Reviews

Books reviewed:
John Twigg and Mihir R. Bhatt, eds, Understanding Vulnerability
Joachim von Braun, Tesfaye Teklu and Patrick Webb, Famine in Africa: Causes, Responses, and Prevention
C. Emdad Haque, Hazrads in a Fickle Environment: Bangladesh
Walter Gillis Peacock, Betty Hearn Morrow and Hugh Gladwin, eds, Population and Food: Global Trends and Future Prospects
Roy Gutman and David Rieff, eds, Crimes of War: What the Public Should Know     

Cross-sectional survey methods to assess retrospectively mortality in humanitarian emergencies

Since the rates and causes of mortality are critical indicators of the overall health of a population, it is important to evaluate mortality even where no complete vital statistics reporting exists. Such settings include humanitarian emergencies. Experience in cross-sectional survey methods to assess retrospectively crude, age-specific, and maternal mortality in stable settings has been gained over the past 40 years, and methods appropriate to humanitarian emergencies have been developed. In humanitarian emergencies, crude and age-specific mortality can be gauged using methods based on the enumeration of individuals resident in randomly selected households—frequently referred to as a household census. Under-five mortality can also be assessed through a modified prior birth history method in which a representative sample of reproductive-aged women are questioned about dates of child births and deaths. Maternal mortality can be appraised via the initial identification of maternal deaths in the study population and a subsequent investigation to determine the cause of each death.     

Web-based surveys as an alternative to traditional mail methods

Environmental economists have long used surveys to gather information about people's preferences. A recent innovation in survey methodology has been the advent of web-based surveys. While the Internet appears to offer a promising alternative to conventional survey administration modes, concerns exist over potential sampling biases associated with web-based surveys and the effect these may have on valuation estimates. This paper compares results obtained from a travel cost questionnaire of visitors to Fraser Island, Australia, that was conducted using two alternate survey administration modes; conventional mail and web-based. It is found that response rates and the socio-demographic make-up of respondents to the two survey modes are not statistically different. Moreover, both modes yield similar consumer surplus estimates.     

Abundance, behavior, and movement patterns of western gray whales in relation to a 3-D seismic survey, Northeast Sakhalin Island, Russia

A geophysical seismic survey was conducted in the summer of 2001 off the northeastern coast of Sakhalin Island, Russia. The area of seismic exploration was immediately adjacent to the Piltun feeding grounds of the endangered western gray whale (Eschrichtius robustus). This study investigates relative abundance, behavior, and movement patterns of gray whales in relation to occurrence and proximity to the seismic survey by employing scan sampling, focal follow, and theodolite tracking methodologies. These data were analyzed in relation to temporal, environmental, and seismic related variables to evaluate potential disturbance reactions of gray whales to the seismic survey. The relative numbers of whales and pods recorded from five shore-based stations were not significantly different during periods when seismic surveys were occurring compared to periods when no seismic surveys were occurring and to the post-seismic period. Univariate analyses indicated no significant statistical correlation between seismic survey variables and any of the eleven movement and behavior variables. Multiple regression analyses indicated that, after accounting for temporal and environmental variables, 6 of 11 movement and behavior variables (linearity, acceleration, mean direction, blows per surfacing, and surface-dive blow rate) were not significantly associated with seismic survey variables, and 5 of 11 variables (leg speed, reorientation rate, distance-from-shore, blow interval, and dive time) were significantly associated with seismic survey variables. In summary, after accounting for environmental variables, no correlation was found between seismic survey variables and the linearity of whale movements, changes in whale swimming speed between theodolite fixes, mean direction of whale movement, mean number of whale exhalations per minute at the surface, mean time at the surface, and mean number of exhalations per minute during a whales surface-to-dive cycle. In contrast, at higher received sound energy exposure levels, whales traveled faster, changed directions of movement less, were recorded further from shore, and stayed under water longer between respirations.