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511.
In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35 ± 1 °C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369–466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000–3000 mgNH4–N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation–emission matrix spectroscopy data showed that food waste was completely degraded.We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production.  相似文献   
512.
We develop a model of hunting, farming and defensive action to study the environmental and economic consequences of introducing a program to compensate peasants of a small economy for the damage caused by wildlife. We show that the widespread belief that compensation induces wildlife conservation may be erroneous. Compensation can lower the wildlife stock, and may result in a net welfare loss for local people.  相似文献   
513.
Limited toxicity data are available for estuarine and marine species and the widely used pyrethroid insecticide, permethrin. This study determined acute effects of permethrin on survival, lipid peroxidation, acetylcholinesterase activity, and splenocyte proliferation for two fish species found in South Carolina estuaries; juvenile red drum (Sciaenops ocellatus) and adult mummichog (Fundulus heteroclitus). Juvenile S. ocellatus were significantly more sensitive than adult F. heteroclitus to permethrin exposure, with a 96-h LC50 value of 8 μg/L determined for red drum compared to 23 μg/L for mummichog. Lipid peroxidation activity of the liver increased in permethrin-treated fish compared to control animals after 24 h and decreased after 96 h. Permethrin had no effect on acetylcholinesterase activity of the brain at the concentrations tested. Permethrin exposure significantly inhibited splenocyte proliferation, indicating an immunosuppressive effect. Most of the effects of permethrin on fish cellular stress enzymes and survival occurred at concentrations much higher than those typically measured in the environment. However, inhibition of splenocyte proliferation in juvenile red drum occurred at approximately twice that of measured permethrin concentrations in surface water. These findings may prove useful to the future management and regulation of pyrethroid insecticide use near estuarine habitats.  相似文献   
514.
Human modification of the environment is driving declines in population size and distributional extent of much of the world's biota. These declines extend to many of the most abundant and widespread species, for which proportionally small declines can result in the loss of vast numbers of individuals, biomass, and interactions. These losses could have major localized effects on ecological and cultural processes and services without elevating a species’ global extinction risk. Although most conservation effort is directed at species threatened with extinction in the very near term, the value of retaining abundance regardless of global extinction risk is justifiable based on many biodiversity or ecosystem service metrics, including cultural services, at scales from local to global. The challenges of identifying conservation priorities for widespread and abundant species include quantifying the effects of species’ abundance on services and understanding how these effects are realized as populations decline. Negative effects of population declines may be disconnected from the threat processes driving declines because of species movements and environment flows (e.g., hydrology). Conservation prioritization for these species shares greater similarity with invasive species risk assessments than extinction risk assessments because of the importance of local context and per capita effects of abundance on other species. Because conservation priorities usually focus on preventing the extinction of threatened species, the rationale and objectives for incorporating declines of nonthreatened species must be clearly articulated, going beyond extinction risk to encompass the range of likely harmful effects (e.g., secondary extinctions, loss of ecosystem services) if declines persist or are not reversed. Research should focus on characterizing the effects of local declines in species that are not threatened globally across a range of ecosystem services and quantifying the spatial distribution of these effects through the distribution of abundance. The case for conserving abundance in nonthreatened species can be made most powerfully when the costs of losing this abundance are better understood.  相似文献   
515.
A 29-year-old woman was referred for suspicion of twin-twin transfusion syndrome (TTTS). Several ultrasonographic and neonatal criteria of TTTS were encountered in this twin pregnancy. The peculiar observations in this case were, firstly, the demonstration of superficial anastomosis by Doppler ultrasound and, secondly, that one single therapeutic amniocentesis could have been sufficient to partially correct the progression of the syndrome, as after amniocentesis it was no longer possible to demonstrate the vascular communication. This observation suggests that superficial anastomoses could also have a role in the genesis of TTTS. Their effect could be monitored by Doppler ultrasound and could be more easily corrected by therapeutic amniocentesis.  相似文献   
516.
Deficiency of amylo-1,6–glucosidase activity was expressed in parallel in liver and skin fibroblasts from a patient with type III glycogenosis. In crude extracts of control liver and muscle, amylo-1, 6–glucosidase (M.W. 164000) was identified by immunoprecipitation; no cross-reacting material was found in the patient's liver. Assay of amylo-1,6–glucosidase activity in cultured skin fibroblasts from the affected family revealed less than 10 per cent of control value in mutant homozygous cells whereas in cells from the parents, activity was reduced to 40–60 per cent of the control value. Activity in cultured amniotic fluid cells was similar to that of control fibroblasts. In cultured amniotic fluid cells obtained during the mother's subsequent pregnancy, the normal amylo–1,6–glucosidase activity measured, predicted correctly the outcome of this pregnancy prior to the 20th week of gestation.  相似文献   
517.
During the last 30 years, growing demand for science-based policy making has contributed to the mobilization of scientific cooperation alongside transnational political arrangements for addressing environmental issues. Following the contemporary trend toward regionalizing environmental policy and practice, many of these scientific joint efforts have focused on a regional scale. This article examines regional scientific cooperation in the context of the institutionalization of mountain regions in Europe. Such cooperation can be observed from the Pyrenees to Central Asia, albeit with a degree of variation that largely remains unexplored in scientific research. Sometimes scientific cooperation served to lay the groundwork of a mountain policy initiative, other times it appeared in its wake; some examples appear as loose networks of individual scientists, others are set up as formalized monitoring and observation centers; finally, some scientific joint efforts are formally linked to, or incorporated in a mountain policy initiative, while others are largely independent. The article proposes a new typology for understanding the interactions between regional scientific mobilization and regional policy making and provides up-to-date portraits of six main cases.  相似文献   
518.
Beckwith–Wiedemann syndrome (BWS) is an overgrowth syndrome associated with congenital malformations and tumour predisposition. BWS results from variable mutations or epigenetic modifications of imprinted genes in the 11p15 chromosomal region. We present a fetus with mild general overgrowth and bilateral enlarged echogenic kidneys with loss of the corticomedullary differentiation in which prenatal diagnosis of BWS was suspected. The rest of the fetal anatomy and the amniotic fluid volume appeared normal. After termination of the pregnancy, molecular analysis confirmed the diagnosis of BWS by showing an isolated hypermethylation of the H19 gene. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
519.
Sanjad–Sakati syndrome (SSS) is an autosomal recessive disorder characterized by congenital hypoparathyroidism, growth and mental retardation. In Saudi Arabia, the disease is caused by a deletion of 12 bp (155-166nt) in the tubulin-specific chaperone E gene. In a family with two affected siblings with SSS, preimplantation genetic diagnosis (PGD) was performed. Fluorescent PCR (F-PCR) was utilized to check the heterozygosity and the homozygosity status of the parents and the affected children, respectively. F-PCR was then optimized for single-cell analysis by using peripheral blood lymphocytes. The patient underwent a cycle with intra-cytoplasmic sperm injection. A total of 11 embryos were obtained and biopsied. There were five heterozygous, three homozygous affected and three normal embryos. One heterozygous and one normal embryo were transferred because of their very good quality (morula). A singleton pregnancy was obtained, and amniosynthesis confirmed the presence of the heterozygous fetus. These results show for the first time, the feasibility of PGD for SSS. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
520.
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