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661.
Ann Curtis Lisa Strain Moira Mennie Susan Holloway J. A. Raeburn G. T. N. Besley D. J. H. Brock 《黑龙江环境通报》1988,8(8):625-628
First-trimester prenatal diagnosis of cystic fibrosis (CF) using linked DNA markers is usually only possible if there is an index affected child to establish the haplotype of the parental chromosomes. We describe a prenatal diagnosis where fibroblasts, cultured from the skin of a deceased affected child and then held in frozen storage for 3 years, were used as the starting point for tracking the CF gene. The fetus was diagnosed as a homozygous normal and the diagnosis confirmed by immunoreactive trypsin testing after birth. It was also possible to establish heterozygosity in the aunt of the affected child. 相似文献
662.
Ecosystem Decay of Amazonian Forest Fragments: a 22-Year Investigation 总被引:49,自引:1,他引:49
663.
We conducted a 3-year field experiment to measure the frequency of bird movements through riparian buffer strips before and after harvesting of adjacent forest. Our study was conducted in the boreal mixed wood forest of Alberta and was designed to determine empirically whether songbirds use riparian buffer strips of forest connecting forest reserves as corridors and if they move along these buffer strips more frequently than they cross adjacent clearcuts. We used mist nets to obtain an index of the frequency of bird movement in the forest, and we observed bird movements across adjacent clearcuts for comparison. We predicted that the frequency of movement would be greater (1) in buffer strips after harvesting of adjacent forest than before harvesting, (2) in buffer strips than across clearcuts and, (3) in buffer strips than at control sites (lakeshore forest with no adjacent clearcuts). After adjusting for year-to-year variation in abundance, we found that capture rates increased significantly from pre- to post-harvest, but only for juveniles. Capture rates of adults decreased immediately after harvesting, probably because of the removal of an adjacent source of birds that previously moved through the lakeside forest. Movement rates of forest species in clearcuts were significantly lower than capture rates in the forest. The number of adults captured was positively correlated with the number of territories in the buffer strips, indicating that most birds captured were probably residents. The number of local territories was a poor predictor of juvenile captures, supporting the notion that juveniles were likely dispersing individuals. Our results indicate that buffer strips enhanced movements of juveniles (i.e., acted as corridors) and maintained movement rates of adults. Furthermore, there appeared to be a threshold distance between reserves below which birds may be less reluctant to fly across openings, making corridor use less important. 相似文献
664.
Evans Meredydd Legro Susan Popov Ilya 《Mitigation and Adaptation Strategies for Global Change》2000,5(4):319-336
Joint implementation (JI) can provide flexibility in meetingKyoto Protocol commitments, and 44 nations have already participated inthe U.N. Framework Convention on Climate Change – Activities Implemented Jointly (AIJ) pilot. Thispaper surveys JI policy and projects in three countries – Russia, Ukraine,and Poland – over the past five years and examines the effects of domesticinstitutions, foreign policy, and investment trends on JI in each country.The institutional and economic situation in the three nations differs greatly,and these distinctions have resulted in very different circumstances for AIJprojects, affecting both their number and scope. Poland has a well-definedset of rules and procedures for JI and its economy is quite strong. Ukrainehas not yet established criteria or clear procedures for AIJ project reviewsalthough it does have an Interagency Commission on Climate Change.Ukraine's economy declined by over 40% in the 1990s. Russia'seconomy has also declined, to a lesser extent. Russia does have aprocedure for reviewing AIJ projects, though it has temporarily halted thesereviews. Countries seeking JI investment can take several steps to improve thenumber and quality of AIJ projects that they receive. In the long term,governments can create macroeconomic stability and a solid legalinvestment basis to attract investment for JI and other areas. In the shortterm, however, governments can undertake several simple and inexpensivesteps to promote JI. Establishing clear rules and procedures for AIJprojects is an important step. So too are clearly delegating responsibilityfor AIJ project review and providing a single JI point of contact in thegovernment to which investors and project developers can turn. Gainingmore experience in implementing AIJ projects now is important preparationfor fully implementing the Kyoto Protocol beginning in 2008. 相似文献
665.
Calcium concentrations were measured in supernatant amniotic fluid in order to establish whether they may be used as a marker for cystic fibrosis. No difference in values were found, whether the sample was derived from a normal pregnancy or from a pregnancy which resulted in a baby affected with cystic fibrosis. 相似文献
666.
Susan L. Carpenter MEd EdD W. J. D. Kennedy 《Environmental geochemistry and health》1980,2(4):159-164
In the 1980s conflicts over the extraction and use of natural resources will increase. While some of these controversies are unavoidable, many are manufactured when people choose inappropriate methods for responding to problems. This paper explores five ways industry creates its own problems and how it can avoid doing so. They are: failure to provide adequate information to the public; relying on stereotypes in making decisions; ignoring a problem, hoping that it will disappear; assuming that technical solutions are sufficient to solve a problem; depending on archaic techniques for conducting business with the public. Specific tools for managing environmental conflict are suggested. 相似文献
667.
668.
669.
Gaps in forest cover, created by agriculture, forestry, and other anthropogenic activities, are assumed to impede the movements of many forest songbirds. Little is known, however, about the reluctance of different species of birds to cross habitat gaps. We studied this by inducing birds in the post-fledging period to cross gaps of varying widths and to choose between routes through woodland or across open areas by attracting them to a recording of mobbing calls by Chickadees ( Parus atricapillus). In 278 experiments conducted in boreal forest and agricultural landscapes near Québec city, 157 birds or flocks of birds of five species were attracted. Overall, birds were twice as likely to travel through 50 m of woodland than through 50 m in the open to reach the recording. When given a choice of traveling through woodland or across a gap, the majority of respondents preferred woodland routes, even when they were three times longer than shortcuts in the open. However, species differed greatly in their response to gaps. Our results show that woodland links significantly facilitate movements of birds across fragmented landscapes. 相似文献
670.
Quality-indicating sexually selected traits may have their honesty maintained by their costs or by an inherent “revealing”
nature. Long tails in birds are usually considered to be costly “handicaps”, but may have additional potential as revealing
indicators through the incidence of breakage. Magpies Pica pica with unbroken and less abraded tails paired earlier, but did not nest or fledge young earlier than pairs with tails in poorer
condition. Pairs mated assortatively by tail quality, and magpies with very broken tails remained unmated. Pairs in which
both members had almost undamaged tails fledged more offspring than pairs with poorer tails. Tail quality did not correlate
with the extent of any habitat type in the territory. Tail damage thus honestly indicated a magpie's reproductive potential,
and the data are consistent with its having a role in mate choice, as a revealing element of tail morphology.
Received: 28 March 1996 / Accepted after revision: 9 December 1996 相似文献