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491.
Ruth?SalwayEmail author Jonathan?Wakefield 《Environmental and Ecological Statistics》2005,12(3):321-347
Ecological studies investigate relationships at the level of the group, rather than at the level of the individual. Although
such studies are a common design in epidemiology, it is well-known that estimates may be subject to ecological bias. Most
discussion of ecological bias has focused on rare disease events, where the tractability of the loglinear model allows some
characterization of the nature of different biases. This paper concentrates on non-rare events, where the Poisson approximation
to the binomial distribution is not appropriate. We limit the discussion to bias that arises from within-area variability
in exposures and confounders. Our aims are to investigate the likely sizes and directions of bias and, where possible, to
suggest methods for controlling the bias or for addressing the sensitivity of inference to assumptions on the nature of the
bias. We illustrate that for non-rare events it is much more difficult to characterize the direction of bias than in the rare
case. A series of simple numerical examples based on a chronic study of respiratory health illustrate the ideas of the paper. 相似文献
492.
Reactive-nitrogen (Nr) has a wide variety of beneficial and detrimental effects on human health. The most important of the beneficial effects are increasing global and regional food supplies and increased nutritional quality of available foods. However, lack of adequate dietary intake of amino acids and proteins is a serious cause of malnutrition when food supplies are inadequate because of poverty, drought, floods, wars, and displacements of people as refugees. There is sufficient, though limited, quantitative data indicating that increased circulation of Nr in the environment is responsible for significant human health effects via other exposure pathways. Nr can lead to harmful health effects from airborne occupational exposures and population-wide indoor and outdoor air pollution exposures to nitrogen dioxide and ozone. Nr can also affect health via water pollution problems, including methemoglobinemia from contaminated ground water, eutrophication causing fish kills and algal blooms that can be toxic to humans, and via global warming. The environmental pollutants stemming from reactive nitrogen are ubiquitous, making it difficult to identify the extent to which Nr exerts a specific health effect. As all populations are susceptible, continued interdisciplinary investigations are needed to determine the extent and nature of the beneficial and harmful effects on human health of nitrogen-related pollutants and their derivatives. 相似文献
493.
Jonathan Levinson 《环境质量管理》1998,7(4):97-110
Environmental Information Services Inc. (EIS) publishes detailed reports and offers custom research related to the full spectrum of environmental issues facing corporations. This article highlights several key sections from EIS's new 1997 Chemical Industry Report. It details the environmental performance, policies, and expenditures of the largest companies in the chemical industry. EIS industry reports contain data on five key performance criteria—toxic waste management, hazardous waste generation, penalties, spills, and Superfund sites. Here we examine one of those—penalties—and the policies of three of the largest companies in the chemical industry. In the full report, which can be obtained from EIS, 15 corporations are analyzed based on all the performance criteria. 相似文献
494.
Albert Robbat Jonathan E. Kenny Sigurdur Smarason Jane Wu Pepper Andrew O. Wright 《补救:环境净化治理成本、技术与工艺杂志》1998,9(1):95-111
This article describes new field-based technologies that support the Dynamic Workplan/Adaptive Sampling and Analysis Program employed to better characterize hazardous waste sites at lower cost. A laser-induced fluorescence (LIF) probe was designed and field-tested with a cone penetrometer (CP) for investigating petroleum contaminants present at under-ground tank farms. The LIF produced real-time quantitative data for naphthalene and semiquantitative results for total petroleum hydrocarbons and diesel range organics. Two different projects are described employing fast gas chromatography/mass spectrometry (GC/MS) in the field. A 70-foot heated transfer line and probe were used in combination with a cone penetrometer to thermally extract (TE) subsurface soil-bound semivolatile organics. In the second project, soil samples were collected by a GeoprobeTM and brought to the surface for analysis. The direct measurement TECP data produced semiquantitative results while the more conventional means of collecting and analyzing samples produced risk analysis quality data in the field. A new set of mass spectrometry algorithms provided the technology breakthrough for identifying and quantifying a wide range of Environmental-Protection-Agency-listed target compounds in the presence of high levels of matrix (petroleum) interferents under fast, 7 min/sample, GC conditions. 相似文献
495.
Dr Simon E. Meagher Nicholas M. Fisk Jonathan G. Harvey Geoffrey F. Watson Antheunis Boogert 《黑龙江环境通报》1993,13(6):495-501
Congenital bronchopulmonary malformations detectable on prenatal ultrasound include cystic adenomatoid malformation (CAM), lobar sequestration, and upper airway atresia. We describe three fetuses with prenatally detected intrathoracic lesions in which the associated pulmonary hyperechogenicity disappeared before delivery. In the first case of pulmonary sequestration, the infant was asymptomatic after birth. However, in a case of CAM and another with laryngeal atresia, respiratory distress developed after delivery, despite recent scans showing apparently normal lung fields. This experience suggests that ultrasonic resolution of hyperechogenic lung lesions in utero does not necessarily indicate resolution of the underlying pathology. 相似文献
496.
In species with more than one male reproductive morph, there typically exists a larger morph with exaggerated secondary sexual characters, and a smaller morph with reduced secondary sexual characters. These exaggerated and reduced morphologies are commonly thought to represent specializations to alternative behavioral reproductive tactics—large body size and exaggerated secondary sexual characters should both facilitate territoriality, courtship, and pair-spawning; while small body size and reduced secondary sexual characters should facilitate sneaky cuckoldry. Given this postulated relationship between morphology and behavior, we examined the relationship between the morphology of exaggerated males and cuckoldry. In a field and aquarium study of the midshipman fish, a fish with both exaggerated and reduced morphs, we demonstrated cuckoldry in some males of the exaggerated morph. Since the reduced morphology is thought to be an adaptation towards sneaky cuckoldry, we predicted that, of males with the exaggerated morph, less-exaggerated (smaller) males would be better able to gain proximity to the spawning pair during cuckoldry. In contrast to that prediction, access to the spawning pair during cuckoldry increased with the body size of the cuckolding exaggerated-morph males. This may be related to our observation that exaggerated males often cuckolded aggressively. Thus the exaggerated morphology need not preclude adaptive plasticity to cuckoldry, and may even aid it. 相似文献
497.
Phenotypic variation plays a critical role in determining the structural organisation and ecological function of wild populations. Animal groups are often structured according to factors such as species, sex, body size and parasite load, but it is unclear whether body shape also influences patterns of social organisation, and thus contributes to population phenotypic structure. Here, we use geometric morphometric analyses to determine whether wild-caught shoals of a freshwater fish, the western rainbowfish (Melanotaenia australis), are structured according to body size and shape. Using randomisation analyses, we show that the level of variation in size and shape observed in natural group assemblages is lower than that expected under a null model of random shoal composition. In addition, we found evidence of further phenotypic structuring along an upstream-downstream environmental gradient. The putative benefits of morphological assortment include a reduction in predation risk (due to prey oddity and predator confusion effects) and increased hydrodynamic or foraging efficiency. We suggest that morphological variation is a neglected component of population social organisation that can affect population processes, such as patterns of gene flow, and ecological interactions, such as predator-prey dynamics. 相似文献
498.
Viruses are a significant cause of morbidity and mortality around the world. Determining the minimum dose of virus particles
that can initiate infection, termed the minimum infective dose (MID), is important for the development of risk assessment
models in the fields of food and water treatment and the implementation of appropriate infection control strategies in healthcare
settings. Both respiratory and enteric viruses can be shed at high titers from infected individuals even when the infection
is asymptomatic. Presence of pre-existing antibodies has been shown to affect the infectious dose and to be protective against
reinfection for many, but not all viruses. Most respiratory viruses appear to be as infective in humans as in tissue culture.
Doses of <1 TCID50 of influenza virus, rhinovirus, and adenovirus were reported to infect 50% of the tested population. Similarly, low doses
of the enteric viruses, norovirus, rotavirus, echovirus, poliovirus, and hepatitis A virus, caused infection in at least some
of the volunteers tested. A number of factors may influence viruses’ infectivity in experimentally infected human volunteers.
These include host and pathogen factors as well as the experimental methodology. As a result, the reported infective doses
of human viruses have to be interpreted with caution. 相似文献
499.
Sana?S.?Syal Robyn?S.?WilsonEmail author J.?Mac?Crawford Jonathan?Lutz 《Mitigation and Adaptation Strategies for Global Change》2011,16(8):911-924
With growing evidence on how climate change impacts human health, public health agencies should develop adaptation programs
focused on the impacts predicted to affect their jurisdictions. However, recent research indicates that public health agencies
in the United States have done little to prepare the public for predicted climate change impacts, largely due in response
to a lack of resources and priority. This study surveyed Environmental Health (EH) Directors across the United States to determine
the extent to which individual level attitudes and beliefs influence the adoption of climate change adaptation programming
in a department. The results indicate that an EH Director’s perception of the health risk posed by climate change explained
27% of the variance in the number of climate change impacts being addressed. Furthermore, the study found that environmental
attitude and political views made strong, unique contributions in explaining the variance in risk perception. The results
provide evidence that individual-level attitudes and beliefs, as well as organizational-level barriers influence the adoption
of climate change adaptation programs in public health agencies. As a result, increasing EH Directors’ perception of risk
by highlighting the likelihood and severity of localized impacts may increase the adoption of adaptation programming despite
existing organizational barriers (e.g., lack of resources). Given the fact that risk perception has been shown to influence
behavior across cultures, these findings are also useful for understanding the influence of individual decision makers on
public health programming around the world. 相似文献
500.
Sota Tanaka Sayaka Tachibe Mohd Effendi Bin Wasli Jonathan Lat Logie Seman Joseph Jawa Kendawang Kozo Iwasaki Katsutoshi Sakurai 《Agriculture, ecosystems & environment》2009,129(1-3):293-301
This study discusses soil fertility under perennial cash crop farming (para rubber, Hevea brasiliensis; black pepper, Piper nigrum; oil palm, Elaeis guineensis) conducted by local farmers and an oil palm estate in an upland area of Sarawak, Malaysia, in comparison with the surrounding secondary forests. In the farmlands of the local farmers, rubber farming was conducted without fertilizer application, while 2–5 t ha?1 of NPK compounds were applied annually on pepper farms. Soils under rubber farming were acidic with poor nutrient contents, resembling soils in secondary forests. In pepper farms, soils were less acidic and showed high nutrient contents, especially with respect to available P and exchangeable Ca. This trend became stronger with increasing farming duration. Fertilizers applied around pepper vines appeared to migrate and spread across the fields. Bulk density and hardness of surface soils were higher in pepper farms than in secondary forests, indicating soil compaction due to field works. In the oil palm estate, annual fertilizer application rates were moderate at 0.4–0.8 t ha?1 of NPK compound fertilizers. However, the soil properties in the oil palm estate were similar to those of the small-scale pepper farms. Close to the bases of the palms where fertilizers usually are applied, the contents of exchangeable Ca and available P were high. Nutrient uptake by the dense root systems of the palms seemed to prevent excessive loss of nutrients through leaching. Loss of soil organic matter and deterioration of soil physical properties were brought about by terrace bench construction, but the soils seemed to recover to some extent over time. In conclusion, technologies such as intercropping and the appropriate allocation of different crops to specific locations as well as the proper selection and dosage of fertilizers should be developed and adopted to improve fertilizer efficiency and prevent water pollution due to fertilizer wash-off from farmlands. 相似文献