共查询到20条相似文献,搜索用时 15 毫秒
1.
Jacob A. Moorad 《Evolution; international journal of organic evolution》2013,67(6):1635-1648
Precopulatory sexual selection is the association between fitness and traits associated with mate acquisition. Although sexual selection is generally recognized to be a powerful evolutionary force, most investigations are limited to characters belonging to individuals. A broader multilevel perspective acknowledges that individual fitness can be affected by aspects of mating success that are characters of groups, such as families. Parental mating success in polygynous or polyandrous human societies may exemplify traits under group‐level sexual selection. Using fitness measures that account for age‐structure, I measure multilevel selection for mate number over 55 years in a human population with declining rates of polygyny. Sexual selection had three components: individual‐level selection for ever‐mating (whether an individual mated) and individual‐ and family‐level selection for polyandry and polygyny. Family‐ and individual‐level selection for polygyny was equally strong, three times stronger than family‐level selection for polyandry and more than an order of magnitude stronger than individual‐level selection for polyandry. However, individual‐level selection for polyandry and polygyny was more effective at explaining relative fitness variance than family‐level selection. Selection for ever‐mating was the most important source of sexual selection for fitness; variation for ever‐mating explained 23% of relative fitness variance. 相似文献
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Margit Alt Murphy Hanna C Persson Anna Danielsson Jurgen Broeren Åsa Lundgren-Nilsson Katharina S Sunnerhagen 《BMC neurology》2011,11(1):56
Background
Recovery patterns of upper extremity motor function have been described in several longitudinal studies, but most of these studies have had selected samples, short follow up times or insufficient outcomes on motor function. The general understanding is that improvements in upper extremity occur mainly during the first month after the stroke incident and little if any, significant recovery can be gained after 3-6 months. The purpose of this study is to describe the recovery of upper extremity function longitudinally in a non-selected sample initially admitted to a stroke unit with first ever stroke, living in Gothenburg urban area. 相似文献4.
Sônia Cristina Oliveira Melo Fernanda Amato Gaiotto Fernanda Barbosa Cupertino Ronan Xavier Corrêa Alessandra Maria Moreira Reis Dário Grattapaglia Rosana Pereira Vianello Brondani 《Conservation Genetics》2007,8(6):1269-1271
Caesalpinia echinata, commonly known as Pau-brasil (Brazilwood), the famous tree that named Brazil is native to the Atlantic forest. Men extensively
exploited it ever since discovery and colonial times due to its value as a source of red dye. As a consequence, Brazilwood
is a threatened species with populations reduced to small forest fragments. Ten polymorphic microsatellite loci were developed
from an enriched genomic library. Using fluorescently-labeled primers, a total of 83 alleles were found after analyzing a
sample of 44 trees. These high genetic information content markers should allow detailed investigations of mating systems,
gene flow, population structure and paternity in natural populations. 相似文献
5.
The apparent difficulty to precisely control fine-tuning of biomaterial degradation has initiated the recent paradigm shift from conventional top-down fabrication methods to more nature-inspired bottom-up assemblies. Sophistication of material fabrication techniques allows today's scientists to reach beyond conventional natural materials in order to synthesise tomorrow's ‘designer material’. Material degradation into smaller components and subsequent release of encapsulated cells or cell-signalling agents have opened medically exploitable avenues, transforming the area of regenerative medicine into a dynamic and self-propagating branch of modern medicine. The aim to synthesise ever more refined scaffolding structures in order to create micro- and nanoenvironments resembling those found in natural tissues now represents an ever growing niche in the materials sciences. Recently, we have developed and conducted the world's first in-human tracheal transplantation using a non-degradable completely synthetic biomaterial. Fuelled by such clinical potential, we are currently developing a biodegradable version suitable for skin tissue engineering and paediatric applications. However, despite enormous efforts, current, as yet insurmountable challenges include precise biomaterial degradation within pre-determined spatial and temporal confines in an effort to release bio-signalling agents in such orchestrated fashion as to fully regenerate functioning tissues. In this review, the authors, almost anti-climactically, ask the readers to step out of the artificially over-constructed spiral of ever more convoluted scaffold fabrication techniques and consider the benefits of controllable bottom-up scaffold fabrication methods. It will further be investigated how scaffold designs and fabrication methods may influence degradation and subsequent release of incorporated elements. A focus will be placed on the delivery of growth factors, stem cells and therapeutic agents alone or in parallel. The difficulties of designing a delivery vehicle capable of delivering multiple factors whilst maintaining distinct release kinetics will be highlighted. Finally, this review will be rounded off with an insight into current literature addressing the recurring issues of degradation product toxicities and suggests means of overcoming those. 相似文献
6.
Licia Colli Annalisa Paglianti Roberto Berti Gilberto Gandolfi James Tagliavini 《Environmental Biology of Fishes》2009,84(1):95-107
The phylogenetic relationships of two cavefish, Phreatichthys andruzzii and Garra barreimiae, belonging to the family Cyprinidae, were investigated by sequencing the mitochondrial cytochrome b gene. These cavefish
species are native to Somalia (eastern Africa) and Oman (southeastern Arabian peninsula), respectively, and so far no molecular
support to their taxonomy and phylogenetic position was ever provided. The analysis of cytochrome b sequences showed that
the species are monophyletic taxa, closely related to each other and to other species of the genus Garra. Molecular clock calculations allowed to date the origin of these hypogaean species back to the Plio-Pleistocene and support
the hypothesis that African cyprinids originated from Miocenic immigrations of Asian ancestors. 相似文献
7.
In the face of rapid environmental and cultural change, long‐term ecological research (LTER) and social‐ecological research (LTSER) are more important than ever. LTER contributes disproportionately to ecology and policy, evidenced by the greater proportion of LTER in higher impact journals and the disproportionate representation of LTER in reports informing policymaking. Historical evidence has played a significant role in restoration projects and it will continue to guide restoration into the future, but its use is often hampered by lack of information, leading to considerable uncertainties. By facilitating the storage and retrieval of historical information, LTSER will prove valuable for future restoration. 相似文献
8.
Timothy F. Murphy 《Bioethics》2019,33(9):1029-1034
According to an almost axiomatic standard in bioethics, moral commitment should ground parents’ relationship with their children, rather than biogenetic relatedness. This standard has been used lately to express skepticism about extending existing assisted reproductive treatments (ARTs) to same‐sex couples and to research into novel fertility interventions for those couples, but this skepticism is misplaced on several grounds. As a matter of access and equity, same‐sex couples seem presumptively entitled to genetic relatedness to their children as far as possible both in regard to existing ARTs and to novel ARTs under investigation. For those worried about the effects of trying to secure biogenetic relatedness for same‐sex couples, it may be noted that same‐sex couples will only ever be a fraction of the parents implicated in propping up “biologism,” as the expectation of biogenetic relatedness it is sometimes called. The cultural force of biologism would survive almost intact even if no same‐sex couples were ever to have genetically related children. It is therefore hard to see why same‐sex couples should forfeit aspirations to biogenetic relationships with their children or enjoy less subsidy for ARTs than the subsidy given to different‐sex couples. As matter of moral consistency, the full implications of the biologism critique have yet to be evaluated relative to different‐sex couples. 相似文献
9.
One ring to rule them all: Current trends in combating bacterial resistance to the β‐lactams
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From humble beginnings of a contaminated petri dish, β‐lactam antibiotics have distinguished themselves among some of the most powerful drugs in human history. The devastating effects of antibiotic resistance have nevertheless led to an “arms race” with disquieting prospects. The emergence of multidrug resistant bacteria threatens an ever‐dwindling antibiotic arsenal, calling for new discovery, rediscovery, and innovation in β‐lactam research. Here the current state of β‐lactam antibiotics from a structural perspective was reviewed. 相似文献
10.
An 18-month-old girl was found to have monosomy for 17q25----qter which resulted from an unequal crossing-over in the mother carrying an apparently balanced translocation 46, XX, t(3;17) (p12;q24). Clinical features of the proband included: cleft palate, micrognathia and glossoptosis. It seems to be the first reported case where a single band deletion in the long arm of chromosome 17 has ever been noted. 相似文献
11.
Expert round table on acceptance re‐implementation of bacteriophage therapy 《Biotechnology journal》2016,11(5):595-600
This multidisciplinary expert panel opinion on bacteriophage therapy has been written in the context of a society that is confronted with an ever‐increasing number of antibiotic resistant bacteria. To avoid the return to a pre‐antibiotic era, alternative treatments are urgently needed. The authors aim to contribute to the opinion formation of relevant stakeholders on how to potentially develop an infrastructure and legislation that paves the way for the acceptance and re‐implementation of bacteriophage therapy. 相似文献
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Xuan Wu Yanli Chen Zheng Xing Christopher Wai Kei Lam Su‐Seng Pang Wei Zhang Zhicheng Ju 《Liver Transplantation》2019,9(21)
The ever‐increasing demand for large‐scale energy storage systems requires novel battery technologies with low‐cost and sustainable properties. Due to earth‐abundance and cost effectiveness, the development of rechargeable potassium ion batteries (PIBs) has recently attracted much attention. Since carbon‐based materials are abundant, inexpensive, nontoxic, and safe, extensive feasibility investigations have suggested that they can become promising anode materials for PIBs. This review not only attempts to provide better understanding of the potassium storage mechanism, but also summarizes the availability of new carbon‐based materials and their electrochemical performance covering graphite, graphene, and hard carbon materials plus carbon‐based composites. Finally, the critical issues, challenges, and perspectives are discussed to demonstrate the developmental direction of PIBs. 相似文献
14.
This paper explores the extent to which women's work for earnings, education and couple communication over family planning influence current contraceptive use and children ever born in Nepal. Data came from the 1996 Nepal Family Health Survey. The findings indicate that education has a significant positive influence on current use of contraception and a significant negative influence on children ever born. There was virtually no relationship between women working and current use of contraception. However, in full models, there was a significant positive relationship for women who earn cash for work on current use and a significant negative relationship for children ever born. Working alone does not increase contraceptive use or reduce the number of children ever born in Nepal, but earning cash for work does. The husband/couple variables also proved to be important determinants of current use of contraception and children ever born. 相似文献
15.
BOGEN E 《California medicine》1959,91(1):8-11
Although fewer patients with tuberculosis are reported in a far advanced stage of the disease than ever before, the proportion of persons dying of tuberculosis whose disease had not previously been diagnosed appears to be increasing. The average length of sanatorium treatment, and the intramural case fatality rates have not shown much decrease. Tuberculosis mortality rates fall during economic depressions and rise with business booms. Epidemics of influenza do not always increase tuberculosis death rates. Common claims to the contrary are not sustained by recent California data. 相似文献
16.
Respiratory cytology continues to play a central role in the diagnosis and staging of thoracic malignancy, although over time indications have changed. Historically, sputum cytology and endobronchial brushings and washings figured prominently, but with the advent of endobronchial and endoscopic ultrasound much greater emphasis is placed on fine needle aspirates from lymph nodes. The advent of targeted sequencing panels for genomic profiling to identify driver mutations and PD-L1 directed immunotherapy means that there is a need to extract increasing amounts of diagnostic and predictive information from ever smaller amounts of diagnostic material. Recent work has demonstrated that cytology samples are well suited to delivering the information required, but in order to understand the limitations of clinical and laboratory techniques, a close working relationship between pathologist and thoracic oncologist is needed to optimise sample procurement and utilisation. 相似文献
17.
The light-mantled sooty albatross is a medium-sized albatross with a circumpolar distribution in the Southern Ocean. The known
breeding sites are restricted to Islands in sub-Antarctic latitudes close to the Antarctic convergence between 46° and 53°S.
In the austral summer season 2008/2009 we discovered a new breeding colony with at least two confirmed and three probable
nests at Fildes Peninsula, King George Island, South Shetland Islands, Antarctica (62°12′S, 59°01′W). The new breeding colony
of light-mantled sooty albatross described here represents the southernmost breeding place of any albatross species ever recorded. 相似文献
18.
《Biodemography and social biology》2013,59(1-2):51-60
Abstract This paper explores the extent to which women's work for earnings, education and couple communication over family planning influence current contraceptive use and children ever born in Nepal. Data came from the 1996 Nepal Family Health Survey. The findings indicate that education has a significant positive influence on current use of contraception and a significant negative influence on children ever born. There was virtually no relationship between women working and current use of contraception. However, in full models, there was a significant positive relationship for women who earn cash for work on current use and a significant negative relationship for children ever born. Working alone does not increase contraceptive use or reduce the number of children ever born in Nepal, but earning cash for work does. The husband/couple variables also proved to be important determinants of current use of contraception and children ever born. 相似文献
19.
John W. Chapman James T. Carlton M. Renee Bellinger April M. H. Blakeslee 《Biological invasions》2007,9(8):995-1008
The closely documented spread of the European periwinkle snail, Littorina littorea from Pictou, Nova Scotia in 1840 to New Jersey by 1870, its near absence in pre-European fossil deposits, and its close association
with human mechanisms of transport from Europe, are among the clearest evidence of a human-mediated marine introduction ever
reported. Genetic data were recently proposed as evidence that North American L. littorea predate European contact and thus, are not introduced. Review of these genetic data and all other data reveals that the simplest
explanation of the modern occurrence of this snail in North America is by human introduction. 相似文献
20.
It has long been held that Eudyptes penguins will only ever develop a maximum of two mature yolky follicles to match their invariant two-egg clutch, an idea
inferred largely from egg removal studies. Combining our own data with those from a previous but rarely cited study and by
applying these to a simple developmental model, we show that macaroni penguins (Eudyptes chrysolophus) develop up to four large, yolky vitellogenic follicles, and they do so despite the fact that they will never lay more than
two eggs or rear more than one chick, a tactic that seems maladaptive given their realized reproductive success. We discuss
these results within the context of the usual pattern of reproductive investment in Eudyptes penguins and suggest a broader significance to modes of clutch size determination among all penguins (order Sphenisciformes). 相似文献