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Cooperatives are increasingly advocated as a means to improve incomes, livelihoods and the sustainability of smallholder farmers. This study analyzes the impact of commercial vegetable cooperative membership on smallholder agricultural performance in Cambodia. Institutional heterogeneities are considered across cooperatives and various econometric techniques are used to control for potential selection bias. The impacts of horticulture on agricultural outcomes are also analyzed. The results indicate that membership of commercial vegetable cooperatives has so far had no effect on agricultural incomes or the value or amounts of agricultural inputs. However, results indicate that membership has affected technology choice, access to credit services and information transmission through technological training. Additionally, there is evidence that horticulture, as a component of overall agricultural diversification, can augment farm income. The results suggest that much of the benefit of cooperative membership stems from the cooperative's provision of services, which might not be easily inferred from measures of member incomes. 相似文献
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Chengrun Wang Mei He Wen Shi Jessie Wong Tao Cheng Xiaorong Wang Lingling Hu Fenfen Chen 《环境科学学报(英文版)》2011,23(10):1721-1728
Combined chemical analyses and biological measurements were utilized to investigate potential toxicological effects and possible mechanisms involved in risk assessment of rare earth elements (REEs) on Vicia faba L. seedlings, which were hydroponically cultivated and exposed to various concentrations of lanthanum (La) for 15 days. The results showed that La contents in both the solution and roots increased with the increase of extraneous La, contributing to hormetic dose responses of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) and endoprotease (EP) isozymes activities, and HSP 70 production enhanced at low doses but suppressed at higher doses of La. These physiological responses constituted antioxidant and detoxification systems against La-induced oxidative stress. The elevated La levels also contributed to oxidatively modified proteins, which were most responsible for subsequent cell death and growth retardation of the roots. By combination of hormetic and traditional threshold dose levels, the threshold dose range was deduced to be 108-195 μg La/g dry weight in the roots, corresponding to 0.90-3.12 mg/L of soluble La in the culture solution. It suggests that persistent applications of REEs may lead to potential ecological risk in the environment. 相似文献
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A familial pericentric inversion of chromosome 19 was detected prenatally in a young primagravida. As far as the authors are aware there are no previous published reports of this rare abnormality being ascertained in this manner. The problems of counselling such a family are considered. 相似文献
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Evaluating Flow Metric‐Based Stream Classification Systems to Support the Determination of Ecological Flows in North Carolina 下载免费PDF全文
Michele C. Eddy Jennifer Phelan Lauren Patterson Jessie Allen Sam Pearsall 《Journal of the American Water Resources Association》2017,53(1):30-41
Hydroecological classification systems are typically based on an assemblage of streamflow metrics and seek to divide streams into ecologically relevant classes. Assignment of streams to classes is suggested as an initial step in the process of establishing ecological flow standards. We used two distinct hydroecological river classification systems available within North Carolina to evaluate the ability of a hydrologic model to assign the same classes as those determined by observed streamflows and to assess the transferability of such systems to ungaged streams. Class assignments were examined by rate of overall matches, rate of class matches, spatial variability in matches, and time period used in class assignment. The findings of this study indicate assignments of stream class: (1) are inconsistent among different classification systems; (2) differ between observed and modeled data; and (3) are sensitive to the period of record within observed data. One clear source of inconsistency/sensitivity in class assignments lies with the use of threshold values for metrics that distinguish stream classes, such that even small changes in metric values can result in different class assignments. Because these two hydroecological classification systems are representative of other classification systems that rely on quantitative decision thresholds, it can be surmised that the use of such systems based on stream flow metrics is not a reliable approach for guiding ecological flow determinations. 相似文献
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This article examines energy priorities for Thailand from the economic, social and environmental perspectives of sustainable development. The article uses a set of indicators devised by the International Atomic Energy Agency in partnership with other international agencies and research institutes in seven countries. Thailand's energy efficiency in the 1980s and 1990s are analysed using energy intensity indicators, and possible impacts on sustainable energy development are highlighted. The early 1990s in particular was an important period for Thailand, as the country was at the height of its economic growth, and a number of energy efficiency and conservation programmes were launched. Energy intensity indicators show continuing and faster growth in energy consumption relative to economic activity. The financial crisis in the late 1990s did halt growth in energy consumption, with positive consequences on environmental emissions, but only temporarily as Thailand's economy quickly started to recover in 2000. Notwithstanding the financial crisis, the other indicators show significant progress in economic and social dimensions. 相似文献
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Smith AG Hansson M Rodriguez-Pichardo A Ferrer-Dufol A Neubert RT Webb JR Rappe C Neubert D 《Environment international》2008,34(3):330-344
The consequences of exposure of people to highly chlorinated polychlorodibenzo-p-dioxins (PCDDs) are much less known than those of TCDD. We report on levels of PCDDs (and PCDFs) in 13 members of two families poisoned by contaminated cooking oil. Originally, all persons displayed chloracne as an early symptom. Persisting hexa- and higher chlorinated PCDDs could be analysed many years after exposure. Highest values found in blood lipids were: OCDD 660,000 pg/g; HpCDD 58,000 pg/g; HxCDDs: 3500 pg/g. None of the participants exhibited increased TCDD levels at the time of study. During a period of 6 years, HpCDD and OCDD disappeared from the blood lipids much faster in persons exposed as children or young adults, than from lipids of their parents. Surface receptors on blood lymphocytes of the members of the two families and the proliferative capacity of these blood cells in the presence of typical stimulants were analysed. Even in family members with the highest body burdens of hexa- to octachlorinated PCDDs we could not detect pronounced changes from a reference population with respect to the immunological markers. Minor deviations of levels of some receptors in a few, but not all, highly exposed persons suggested a similar trend to those reported in previous studies of persons with body burdens of > or =3000 pg TCDD/g blood lipids. An increase in the number of total blood lymphocytes in some subjects exposed as children may have similarity with highly TCDD-exposed children in Seveso. 相似文献