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211.
A prenatal diagnosis of arthrogryposis multiplex congenita (AMC) has been carried out on a 19-week-old fetus by means of echography. The ultrasonographic characteristics were unnatural position of the four limbs associated with articular anomalies together with absence of active fetal movements. A therapeutic interruption of pregnancy was performed and the diagnosis was confirmed. At autopsy, architectural disorder of the motor neurons of the anterior medullary horn revealed a neuropathic pathogenesis of the arthrogryposis. Moreover, at the lumbar level the spinal cord was progressively replaced by heterotopic bony tissue which caused a more severe deformity of the lower limbs compared with the upper. The aspects of anatomo-pathological, genetic, and differential diagnosis are discussed showing the precocity of the prenatal diagnosis and the peculiarity of the aetiology of our case.  相似文献   
212.
213.
Within the context of the EU Water Framework Directive (EUWFD), there is a demand for a holistic quality improvement of aquatic systems. Therefore, it is obvious that biodiversity is one of the quality components and hence has to be considered in detail. The ranking of habitats, based on biodiversity indices, depends on the specific measurement selected. It is postulated that a ranking of habitats by means of a biodiversity index may be ambiguous. Concepts to resolve this dilemma are demonstrated, and a graphical formalism is introduced which up to now has only been used in quantum mechanics, statistical mechanics, and theoretical chemistry: The YOUNG-diagram technique.  相似文献   
214.
Throughout Central America, the United States Agency for International Development (USAID), and the Zamorano Pan-American Agricultural School support a Safe Pesticide Use program. In 1993, a study of results was carried out among farmers and housewives in eastern Guatemala. Aspects of the methodology included: (1) participation of extension workers in all aspects of the study; (2) small, region-focused samples (eight cells, 30 interviews per cell); (3) comparison to control groups of untrained farmers and housewives; (4) a traditional questionnaire for studying acquisition of specific knowledge; and (5) a flexible instrument for building a cognitive map of knowledge and beliefs regarding pesticides. The cognitive map is a step toward applying modern psychocultural scaling, an approach already well developed for medicine and public health, to environmental problems. Positive results detected include progress at learning the meaning of colors on containers that denote toxicity and where to store pesticides. Pesticide application problems detected were mention by farmers of highly toxic, restricted pesticides as appropriate for most pest problems and of insecticides as the correct solution to fungus problems, and the widespread belief that correct pesticide dosage depends on number of pests seen rather than on land or foliage surface. Health-related problems detected were admission by a vast majority of housewives that they apply highly toxic pesticides to combat children's head-lice; low awareness that pesticides cause health problems more serious than nausea, dizziness, and headaches; and a common belief that lemonade and coffee are effective medicines for pesticide poisoning.  相似文献   
215.
In a study of the relations of staffing sufficiency to a variety of job enrichment constructs, eighty-three supervisors provided data on job-related attitudes and the extent of workgroup staffing sufficiency. Trend analysis provided support for a proposed curvilinear relation between staffing sufficiency and certain job enrichment constructs. In addition, moderate support was also obtained for Greenberg's (1979) proposal that moderate understaffing is optimally related to reactions to one's job. The potential of this research area for the understanding of enrichment processes is proposed.  相似文献   
216.
The problem of assessing the sustainability of human development is discussed in theoretical and practical terms.In Part I, two theoretical tools for describing the challenge of assessing sustainable development are introduced and briefly discussed: (i) the use of an energetic model to describe the dynamic interaction between the human and the biophysical compartment; (ii) basic concepts derived from the hierarchy theory applied to the development of human society. Sustainable and ethical development of human society requires the consideration of three hierarchical levels: the biosphere, the societal and the individual level. Such a holistic assessment can be obtained by integrating scientific and ethical considerations.In Part II, data illustrating the current terms of the dilemma of human development are presented and discussed within the theoretical frame provided in Part I. It is argued that even if we had a better understanding of the consequeces of human activity on the biosphere, current modes of organization of human society and its economic activity do not readily enable adequate planning for the sustainable development of mankind. Ideologies that can bias the discussion and the assessment of sustainable and ethical development are discussed. No solution is at hand; therefore, when we consider human development today, we are facing a high level of uncertainty.  相似文献   
217.
Megacities and atmospheric pollution   总被引:12,自引:0,他引:12  
About half of the world's population now lives in urban areas because of the opportunity for a better quality of life. Many of these urban centers are expanding rapidly, leading to the growth of megacities, which are defined as metropolitan areas with populations exceeding 10 million inhabitants. These concentrations of people and activity are exerting increasing stress on the natural environment, with impacts at urban, regional and global levels. In recent decades, air pollution has become one of the most important problems of megacities. Initially, the main air pollutants of concern were sulfur compounds, which were generated mostly by burning coal. Today, photochemical smog--induced primarily from traffic, but also from industrial activities, power generation, and solvents--has become the main source of concern for air quality, while sulfur is still a major problem in many cities of the developing world. Air pollution has serious impacts on public health, causes urban and regional haze, and has the potential to contribute significantly to climate change. Yet, with appropriate planning, megacities can efficiently address their air quality problems through measures such as application of new emission control technologies and development of mass transit systems. This review is focused on nine urban centers, chosen as case studies to assess air quality from distinct perspectives: from cities in the industrialized nations to cities in the developing world. While each city--its problems, resources, and outlook--is unique, the need for a holistic approach to the complex environmental problems is the same. There is no single strategy in reducing air pollution in megacities; a mix of policy measures will be needed to improve air quality. Experience shows that strong political will coupled with public dialog is essential to effectively implement the regulations required to address air quality problems.  相似文献   
218.
Levels of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in both air and soil samples were measured at three different sites in Italy, in proximity to three municipal solid waste incinerators (MSWIs) to determine baseline contamination and the contributory role of incinerator emissions. At the first site, located in an agricultural, cattle-breeding, typically flattish area of the Po Valley, the dioxin concentrations had already been measured before the start-up of the new MSWI. These dioxin concentrations were then again measured after two years of continual operation of the incinerator. Despite the presence of the plant, the PCDD/Fs concentrations appear not to have been affected and were found to be in a range of 22-125 fg I-TEQ m(-3) in the air samples and 0.7-1.5 pg I-TEQ g(-1) in the soil samples. The second site is located in an industrial district of the Veneto Region, in the surroundings of an old MSWI that is not equipped with Best Available Technology (BAT) dioxin removal system. The PCDD/Fs concentrations in the air samples were between 144 and 337 fg I-TEQ m(-3). This is a typical range of values for industrial areas, while the soil samples showed contamination levels between 1.1 and 1.4 pg I-TEQ g(-1). The third site lies in the Adige Valley, near a MSWI that has been equipped with BAT for flue gas cleaning. The observed values ranged from 10 to 67 fg I-TEQ m(-3) for the air samples and 0.08-1.2 pg I-TEQ g(-1) for the soil samples. The contributory factors of the varying characteristics of the different areas together with the types of technology adopted at each MSWI plant are discussed. The PCDD/Fs levels are subsequently compared with established values from previous studies.  相似文献   
219.
Field observation and laboratory experiments were conducted to investigate sperm competition and patterns of sperm fertilization under different experimental conditions in the carrion ball-roller beetle Canthon cyanellus cyanellus. Males in nature can mate with females whose spermathecae contains fertile sperm from other males. Sperm precedence was investigated using a visible genetic marker. The progeny of red (homozygous recessive) virgin females mated once with a red male and afterward, once with a green beetle (homozygous dominant) and vice versa, revealed that regardless of its color, the last male to mate fertilized c.a. 50% of the eggs, suggesting strong sperm competition. Males were able to achieve higher levels of paternity (more than 80%) when mated ad libitum with previously mated females, although large amount of variance in paternity does not exclude the possibility of first male sperm precedence or female cryptic choice. These results suggest that repeated mating and sperm replacement are the mechanisms by which last males achieve sperm precedence.  相似文献   
220.
一组众所周知的化学药品已被划分为持久性有机污染物(POPs)1.它们的性质包括高毒性、在环境中保留时间长、在大气中可长距离传播和能在脂肪组织中累积.与持久性有机污染物直接接触可以导致急性效应、持久性有机污染物用作农药的事故,例如,已经有使农业劳动者致死或重病的例子.……  相似文献   
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