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Scholars, policy-makers and advocates have, in the last decade, recommended greater involvement by non-governmental organizations (NGOs) in community forest management in developing countries. Behind these recommendations lies a notion that NGOs are a sound complement to formal governments and that NGOs can improve communities’ abilities to manage their own forests. There is limited empirical work, however, testing how NGO activity affects local forest governance and deforestation. This paper reports the results of quantitative statistical tests on the effects of local NGO importance—as measured by local forest users’ reports of NGO importance—on deforestation in a sample of 200 rural Bolivian communities. In addition, it examines the effect of NGO importance on community forestry institutions—specifically, the presence of institutions for rule-making, forest monitoring, sanctioning, and enforcement of rules. Contrary to earlier research, these results suggest that NGOs have no discernible effect on community forestry institutions, though other external actors—most notably, municipal governments—seem to have a positive effect. The paper also reports a negative correlation of NGO importance on deforestation. Although these quantitative results are in part supported by qualitative field observations in selected Bolivian communities, care is needed in drawing generalized causal inferences from this evidence. 相似文献
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Halldin K 《Domestic animal endocrinology》2005,29(2):420-429
Many environmental contaminants can interact with the endocrine system, thereby potentially disrupting the reproductive fitness of individuals. In avian species, the egg-yolk is a major route for excretion of lipophilic compounds by the adult female bird and embryos are exposed to contaminants that have been deposited in the eggs. The reproductive and neuroendocrine system of Japanese quail undergoes sexual differentiation during embryo development. The phenotypic sex, including sex-specific adult behavior, is hormonally imprinted already before hatching. The sexual differentiation of the brain in quail is sensitive to estrogens and the presence of estrogen results in a female phenotype. The relatively low concentration of estrogens in male embryos, on the other hand, results in a male behavioral phenotype. The behavior of male quail can be demasculinized by estrogen exposure during the period of sexual differentiation, and estrogen-exposed males are not able to display a male-typical behavior as adults. Also, differentiation of the reproductive organs is sensitive to hormones during embryogenesis, and an excess of estrogens can for instance induce persistent morphological changes in the reproductive organs of females. Our research has focused on effects in adult birds after embryonic estrogen exposure. We have studied sexual behavior and other reproductive variables in adult quail after in ovo injection of known and suspected estrogenic compounds. Synthetic estrogens and insecticides, such as o,p'-DDT altered the development of the neural system and resulted in demasculinization of male quail. In females, o,p'-DDT caused morphological changes of the oviduct and egg laying was reduced. Our studies suggest that the neural system and the female reproductive system of avian embryos are very sensitive to the effects of chemicals with estrogenic activity. 相似文献
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Nils-Erik Ahlberg MD PhD Kerstin Hansson VDM Leif Svensson PhD Krister Iwarsson VDM PhD 《Veterinary radiology & ultrasound》1989,30(6):253-260
Heart volume mensuration was evaluated on conventional radiographs from eight normal cats in different body positions using computed tomography (CT). Heart volumes were calculated from orthogonal thoracic radiographs in ventral and dorsal recumbency and from radiographs exposed with a vertical X-ray beam in dorsal and lateral recumbency using the formula for an ellipsoid body. Heart volumes were also estimated with CT in ventral, dorsal, right lateral and left lateral recumbency. No differences between heart volumes from CT in ventral recumbency and those from CT in right and left lateral recumbency were seen. In dorsal recumbency, however, significantly lower heart volumes were obtained. Heart volumes from CT in ventral recumbency were similar to those from radiographs in ventral and dorsal recumbency and dorsal/left lateral recumbency. Close correlation was also demonstrated between heart volumes from radiographs in dorsal/ left lateral recumbency and body weights of the eight cats. 相似文献
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