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71.
Borggaard OK  Gafur A  Petersen L 《Ambio》2003,32(2):118-123
An integrated socioeconomic and erosion study on the sustainability of traditional shifting cultivation (Jhum) carried out in 1998 and 1999 in the Chittagong Hill Tracts (CHT) of Bangladesh showed the system to be nonsustainable under the current conditions with fallow periods of only 3-5 years and lack of land rights. An estimated input (mainly labor) of USD 380 ha(-1) yr(-1) results in only a total output of USD 360 ha(-1) yr(-1) and Jhum cultivated areas suffer severe loss of soil and valuable plant nutrients along with runoff during the rainy season. To compensate these losses by commercial fertilizers will cost nearly USD 2 million yr(-1) for CHT. To ensure long-term productivity of the soils, Jhum should therefore be adjusted to a tolerable level and farmers should be given rights and title to the land to motivate them to switch to improved, settled farming systems.  相似文献   
72.
Due to the lack of valid injury data, the objective of this study was to assess the injury morbidity and mortality in a local community of Bangladesh. A population-based survey of 3,258 households was conducted in 1996. The information was collected by trained field-level health workers using three pretested structured forms. The estimated crude morbidity from injuries was 311 per 1,000 population per year, and injury accounted for 13% of all morbidity. The children and old-age groups experienced higher injury rates than others, and male children aged 5–15 years had the highest incidence rates (546/1,000 person-years). Falls and cutting injuries tended to be the most frequently (62.4%) observed types of injuries in this survey. The home (42%) and workplace (42%) were where most of the injuries occurred, and the majority (70.7%) of the injuries were minor. Of all deaths, mortality from injuries was 2.9%, and drowning (27.8%) and homicide (16.7%) were found as common forms of injury-causing deaths. This study invites more detailed investigation on injury morbidity and mortality.  相似文献   
73.
引言 轮垦是一种已存在多年的耕作方法,意味着从大气或从尘土沉降中得到补充的并逐渐释放到土壤中的植物营养物质在休耕期间积累在植被和土壤中.在通过砍伐和焚烧清除天然植被之后,耕地可种植庄稼1年或2年,然后让天然植被复原[1].  相似文献   
74.
Sixty healthy non-smoking white collar employees, aged 30–50, from a large corporation in Sweden participated in the study. There were four groups: 15 male and 15 female middle managers, 15 male and 15 female clerical workers. Each participant was examined individually with regard to cardiovascular and neuroendocrine functions and self-reports for 12 consecutive hours under each of two conditions: (1) a normal day at work (9 a.m.–5 p.m.) and after work (6–9 p.m.), and (2) for the same time period during work-free conditions at home. In addition, everyone was given a videotaped type A-interview and a general health check-up including blood-lipid determination. Attitudes towards work, total workload (including responsibilities outside the paid work) and sex role identity were examined by questionnaires. As expected, all groups showed a moderate increase in cardiovascular and neuroendocrine activity during the day at work. After work, however, interesting group differences emerged, suggesting slower unwinding in female managers. Differences related to occupational level and/ or sex were found for autonomy and social support at work, competitiveness, sex role and reported conflict between demands from paid work and other responsibilities. The stress profile of the female managers was considered in terms of possible long-term health risks.  相似文献   
75.
A field investigation was conducted on a Louisiana Spartina alterniflora shoreline to evaluate the toxic effects of crude oil (Alaska North Slope crude oil, ANSC) and dispersed oil (ANSC + dispersant Corexit 9,500) on three aquatic species indigenous to the Gulf of Mexico: Fundulus grandis (Gulf killifish), Crassostrea virginica (Eastern oyster), and Litopenaeus setiferus (white shrimp). Results indicated that total hydrocarbons concentration value in oiled treatments decreased rapidly in 3h and were below 1 ppm at 24h after initial treatment. Corexit 9,500 facilitated more ANSC fractions to dissolve and disperse into the water column. L. setiferus showed short-term sensitivity to the ANSC and ANSC + 9,500 at 30 ppm. However, most test organisms (>83%) of each species survived well after 24h exposure to the treatments. Laboratory tests conducted concurrent with the field investigation indicated that concentrations of crude oil higher than 30 ppm were required for any significant toxic effect on the juvenile organisms tested.  相似文献   
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