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排序方式: 共有910条查询结果,搜索用时 15 毫秒
871.
The presence of Troglochaetus beranecki is reported in the phreatic groundwater of eskers in southern Finland within the area
covered by glaciers during the last glacial epoch. The hitherto known distribution of this species includes central and southern
Europe and parts of northern America, but it has not previously been found in northern Europe, where groundwater invertebrates
have generally been assumed to be lacking. The limit of distribution of this species is now moved 1500 km to the north-east.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
872.
Jukka T. Salonen 《Free radical research》2013,47(12):1299-1306
Self-selected supplementation of vitamin E has been associated with reduced coronary events and atherosclerotic progression, but the evidence from clinical trials is controversial. ASAP was a 6-year randomized trial to study the effect of supplementation with vitamin E plus slow-release vitamin C on carotid atherosclerotic progression in 520 hypercholesterolemic men and women aged 45-69 years. The supplementation reduced the progression of carotid atherosclerosis by 26% ( P =0.014), by 33% ( P =0.024) in men and 14% (not significant) in women. The effect was larger in subjects with low baseline vitamin C or atherosclerotic plaques. In the Harvard IVUS trial, the combined supplementation with vitamins E and C significantly inhibited the progression of coronary atherosclerosis in one year. These data confirm that the supplementation with a combination of vitamins E and C can retard atherosclerotic progression. The findings of completed trials testing the effect on cardiovascular events are less consistent. The major on-going clinical trials include the SU.VI.MAX, WHS, WACS and WAVE studies. These involve in total over 80,000 subjects, who are treated with antioxidative supplements for years. The results of these studies will become available during 2003-2006. They may provide the necessary additional information concerning the effect of antioxidants on cardiovascular events. 相似文献
873.
Gabrielle L. Harrow John A. Lees William P. Hanage Marc Lipsitch Jukka Corander Caroline Colijn Nicholas J. Croucher 《The ISME journal》2021,15(5):1523
Streptococcus pneumoniae can be divided into many strains, each a distinct set of isolates sharing similar core and accessory genomes, which co-circulate within the same hosts. Previous analyses suggested the short-term vaccine-associated dynamics of S. pneumoniae strains may be mediated through multi-locus negative frequency-dependent selection (NFDS), which maintains accessory loci at equilibrium frequencies. Long-term simulations demonstrated NFDS stabilised clonally-evolving multi-strain populations through preventing the loss of variation through drift, based on polymorphism frequencies, pairwise genetic distances and phylogenies. However, allowing symmetrical recombination between isolates evolving under multi-locus NFDS generated unstructured populations of diverse genotypes. Replication of the observed data improved when multi-locus NFDS was combined with recombination that was instead asymmetrical, favouring deletion of accessory loci over insertion. This combination separated populations into strains through outbreeding depression, resulting from recombinants with reduced accessory genomes having lower fitness than their parental genotypes. Although simplistic modelling of recombination likely limited these simulations’ ability to maintain some properties of genomic data as accurately as those lacking recombination, the combination of asymmetrical recombination and multi-locus NFDS could restore multi-strain population structures from randomised initial populations. As many bacteria inhibit insertions into their chromosomes, this combination may commonly underlie the co-existence of strains within a niche.Subject terms: Population genetics, Microbial ecology, Microbial genetics, Bacterial genetics, Phylogenetics 相似文献
874.
Jukka Särkkä 《Ecography》1982,5(4):396-404
In material sampled from 0.5–6 m on two sampling dates and three subareas the dominant Oligochaeta were Limnodrilus hoffmeisteri Claparède and Peloscolex ferox (Eisen), both composing more than 30% of the abundances of oligochaetes present. The numbers of Oligochaeta were mostly higher in August than in May. Regional differences could be found although the lake seems to be very homogenous. Temporal and vertical variations were detectable in separate subareas. The oligochaete biomass was maximal at 2 m depth. In soft bottom sediments the oligochaetes composed 15.9% of macrobenthos biomass and 12.2% of numbers, but on the stony bottom only 1.9% of numbers. The ratio of Oligochaeta/Chironomidae was similar to those in profundals of oligotrophic lakes. Correlation coefficients between species and two measures of niche overlap were in partial agreement. A temporal niche seems to occur: when the chironomid larvae decrease during the summer, the oligochaetes increase. 相似文献
875.
Jukka Varelius 《Bioethics》2016,30(9):663-671
The view that voluntary active euthanasia and physician‐assisted suicide should be made available for terminal patients only is typically warranted by reference to the risks that the procedures are seen to involve. Though they would appear to involve similar risks, the commonly endorsed end‐of‐life practices referred to as passive euthanasia are available also for non‐terminal patients. In this article, I assess whether there is good reason to believe that the risks in question would be bigger in the case of voluntary active euthanasia and physician‐assisted suicide than in that of passive euthanasia. I propose that there is not. On that basis, I suggest that limiting access to voluntary active euthanasia and physician‐assisted suicide to terminal patients only is not consistent with accepting the existing practices of passive euthanasia. 相似文献
876.
877.
Jukka Varelius 《Bioethics》2019,33(1):195-200
In the end‐of‐life context, alleviation of the suffering of a distressed patient is usually seen as a, if not the, central goal for the medical personnel treating her. Yet it has also been argued that suffering should be seen as a part of good dying. More precisely, it has been maintained that alleviating a dying patient’s suffering can make her unable to take care of practical end‐of‐life matters, deprive her of an opportunity to ask questions about and find meaning in and for her existence, and detach her from reality. In this article, I argue that the aims referred to either do not support suffering or are better served by alleviating it. When the aims would be equally well served by enduring suffering and relieving it, the latter appears to be the preferable option, given that the distress a patient experiences has no positive intrinsic value. Indeed, as the suffering can be very distressing, it may not be worth bearing even if that was the best way to achieve the aims: the distress can sometimes be bad enough to outbalance the worth of achieving the goals. Having considered an objection to the effect that a patient can have a self‐regarding moral duty to endure the distress she faces at the end of life, I conclude that the burden of proof is on the side of those who maintain that the suffering experienced at the end of life ought to be endured as a part of dying well. 相似文献
878.
879.
One suggested anti‐predator function of alarm calls is to deliver a message to a predator that it has been detected. Moreover, giving the alarm call could provide a signal to the predator that capturing the individual giving the alarm is more difficult than capturing its silent group members, as the caller is probably the most aware of the predator's location. In an aviary experiment using stuffed dummy Willow Tits Poecile montanus, we assessed whether an authentic alarm call given by Willow Tit affected Pygmy Owl Glaucidium passerinum prey preference. In the experiment, the Owls attacked only the ‘silent’ dummy individuals, suggesting that alarm calling could offer direct fitness benefits to the caller by decreasing the attack risk of the caller relative to its group members. 相似文献
880.
Susanna Kangas Tapani Lyytikäinen Jukka Peltola Jukka Ranta Riitta Maijala 《Acta veterinaria Scandinavica》2007,49(1):35