共查询到20条相似文献,搜索用时 15 毫秒
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T Uetake 《American journal of physical anthropology》1992,89(1):19-27
Twenty healthy men were asked to walk as straight as possible to a target 60 m away at normal speed. A series of footprints was recorded for each subject by having him wear socks soaked with red ink and walk on white paper fixed flat to the floor. Fourier analysis was applied to determine whether the subjects actually were able to walk straight, and the results revealed that all walked in a sinuous line rather than a straight line. Periodicity and amplitude of the meandering differed from subject to subject. These facts suggest that none of us can walk in a strictly straight line; rather, we meander, primarily due to a slight structural or functional imbalance of our limbs, which produces a gait asymmetry, and secondarily due to feedback from our sense of sight, which acts to correct the shifted walking course. 相似文献
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Andrzej K. Kamocki Aleksander Kołos Piotr Banaszuk 《Wetlands Ecology and Management》2017,25(3):359-367
The main aim of this study was to determine the effectiveness of removing invasive downy birch in non-forest peatland applying a single cut. We tested whether the removal of birch was positively related to the height of cutting, season of the year and age of the trees. Our study showed that birch trees cut at the higher tested height exhibited a lower survival rate than those cut below or just above the ground level. Furthermore, the winter cut produced more non-sprouting stumps than those recorded after the cut performed in autumn. In our opinion, winter cutting at breast height is the best management strategy for downy birch control. However, we suppose that the effective elimination of birch by applying a single cut is not possible, and the treatment should be repeated in subsequent years or boosted by additional treatments. 相似文献
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D S Barrett 《BMJ (Clinical research ed.)》1990,301(6766):1429-1430
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Can we integrate bioinformatics data on the Internet? 总被引:2,自引:0,他引:2
Martin AC 《Trends in biotechnology》2001,19(9):327-328
The NETTAB (Network Tools and Applications in Biology) 2001 Workshop entitled 'CORBA and XML: towards a bioinformatics-integrated network environment' was held at the Advanced Biotechnology Centre, Genoa, Italy, 17-18 May 2001. 相似文献
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Journal of Mathematical Biology - We consider an integro-difference model to study the effect of a stationary barrier zone on invasion of a population with a strong Allee effect. It is assumed that... 相似文献
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Blend MJ 《Perspectives in biology and medicine》2005,48(1):138-142
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Christopher L. Jerde 《Journal of fish biology》2021,98(2):341-353
Environmental (e)DNA, as a general approach in aquatic systems, seeks to connect the presence of species' genetic material in the water and hence to infer the species' physical presence. However, fisheries managers face making decisions with risk and uncertainty when eDNA indicates a fish is present but traditional methods fail to capture the fish. In comparison with traditional methods such as nets, electrofishing and piscicides, eDNA approaches have more sources of underlying error that could give rise to false positives. This has resulted in some managers to question whether eDNA can be used to make management decisions because there is no fish in hand. As a relatively new approach, the methods and techniques have quickly evolved to improve confidence in eDNA. By evaluating an eDNA based research programmes through the pattern of the eDNA signal, assay design, experimental design, quality assurance and quality control checks, data analyses and concurrent search for fish using traditional gears, the evidence for fish presence can be evaluated to build confidence in the eDNA approach. The benefits for fisheries management from adopting an eDNA approach are numerous but include cost effectiveness, broader geographic coverage of habitat occupancy, early detection of invasive species, non-lethal stock assessments, exploration of previously inaccessible aquatic environments and discovery of new species hidden beneath the water's surface. At a time when global freshwater and marine fisheries are facing growing threats from over-harvest, pollution and climate change, we anticipate that growing confidence in eDNA will overcome the inherent uncertainty of not having a fish in hand and will empower the informed management actions necessary to protect and restore our fisheries. 相似文献
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Fanie Pelletier Marco Festa‐Bianchet Jon T. Jorgenson Chiarastella Feder Anne Hubbs 《Ecology and evolution》2014,4(17):3375-3382
Human harvests can unwittingly drive evolution on morphology and life history, and these selective effects may be detrimental to the management of natural resources. Although theory suggests that harvest refuges, as sources of unselected animals, could buffer the effects of human exploitation on wild populations, few studies have assessed their efficiency. We analyzed records from >7000 trophy bighorn rams (Ovis canadensis) harvested in Alberta, Canada, between 1974 and 2011 to investigate if the movement of rams from refuges toward harvested areas reduced the effects of selective harvesting on horn size through phenotypic rescue. Rams taken near refuges had horns on average about 3% longer than rams shot far from refuges and were slightly older, suggesting migration from refuges into hunted areas. Rams from areas adjacent to and far from harvest refuges, however, showed similar declines in horn length and increases in age at harvest over time, indicating a decreasing rate of horn growth. Our study suggests that the influx of rams from refuges is not sufficient to mitigate the selective effects of sheep trophy harvest. Instead, we suggest that selective hunting of highly mobile animals may affect the genetic structure of populations that spend part of the year inside protected areas. 相似文献
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Can we ever identify the Urmetazoan? 总被引:1,自引:0,他引:1
Unraveling the root of the metazoan tree of life has been adifficult task since the time of Haeckel and the invention ofphylogenetics. Even considerable amounts of recent moleculardata have not provided a generally accepted answer. Here, wereview the major problems of this phylogenetic conundrum andprovide some directions for solving it. 相似文献
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J Le Grand 《BMJ (Clinical research ed.)》1993,307(6911):1018-1019
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Silvia De Monte Alice Soccodato Séverine Alvain Francesco d'Ovidio 《The ISME journal》2013,7(10):2054-2056
Understanding the variability of marine biodiversity is a central issue in microbiology. Current observational programs are based on in situ studies, but their implementation at the global scale is particularly challenging, owing to the ocean extent, its temporal variability and the heterogeneity of the data sources on which compilations are built. Here, we explore the possibility of identifying phytoplanktonic biodiversity hotspots from satellite. We define a Shannon entropy index based on patchiness in ocean color bio-optical anomalies. This index provides a high resolution (1 degree) global coverage. It shows a relation to temperature and mid-latitude maxima in accordance with those previously evidenced in microbiological biodiversity model and observational studies. Regional maxima are in remarkable agreement with several known biodiversity hotspots for plankton organisms and even for higher levels of the marine trophic chain, as well as with some in situ planktonic biodiversity estimates (from Atlantic Meridional Transect cruise). These results encourage to explore marine biodiversity with a coordinated effort of the molecular, ecological and remote sensing communities. 相似文献
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