首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
This paper focuses on the changes occurring in households in the indigenous Rana Tharus community. I discuss the household not in terms of physical structure but instead on the social aspects: how people relate to each other through the lens of the household context. I argue that the fluid nature of households makes its flexible to different ecological environments and socio‐economic scenarios. My ethnography of Rana households clearly illustrated that the formation, structure and management of Rana households was fundamentally linked to people's livelihoods. Before 1950s, abundant land resources allowed Ranas to live in joint‐type households. This particular household arrangement not only fulfilled labour needs but also secured the mutual security for every household member. Gradually, undivided and big households (known in Rana as Badaghar) became the ideal model for Ranas as soon as such establishments did not become divided or separated. This household structure also served as an important safety net for most Ranas and fundamental to other social relationships especially Mukhiya (household head system) and Kurmaa (patrilineal kin). However, since the 1950s, new socio‐economic landscapes have significantly challenged the maintenance of traditional Rana households. Within the lifetime of most Ranas, they first experienced household fission and the disappearance of the Mukhiya system. The dynamic relationships between Rana household and new ecological, social and economic landscapes are explored here. It is concluded that the household is a critical institution allowing anthropologists to better understand the long‐term social impacts caused by state policies and ecological changes. This is because people often practice their new household relations in their everyday life as a response to environmental and livelihood changes.  相似文献   

2.
Ben Davies 《Bioethics》2016,30(6):462-468
Greg Bognar has recently offered a prioritarian justification for ‘fair innings’ distributive principles that would ration access to healthcare on the basis of patients' age. In this article, I agree that Bognar's principle is among the strongest arguments for age‐based rationing. However, I argue that this position is incomplete because of the possibility of ‘time‐relative' egalitarian principles that could complement the kind of lifetime egalitarianism that Bognar adopts. After outlining Bognar's position, and explaining the attraction of time‐relative egalitarianism, I suggest various ways in which these two kinds of principle could interact. Since various options have very different implications for age‐based rationing, proponents of such a rationing scheme must take a position on time‐relative egalitarianism to complement a lifetime prioritarian view like Bognar's.  相似文献   

3.
Jonathan Pugh 《Bioethics》2015,29(3):145-152
Jurgen Habermas has argued that carrying out pre‐natal germline enhancements would be inimical to the future child's autonomy. In this article, I suggest that many of the objections that have been made against Habermas' arguments by liberals in the enhancement debate misconstrue his claims. To explain why, I begin by explaining how Habermas' view of personal autonomy confers particular importance to the agent's embodiment and social environment. In view of this, I explain that it is possible to draw two arguments against germline enhancements from Habermas' thought. I call these arguments ‘the argument from negative freedom’ and ‘the argument from natality’. Although I argue that many of the common liberal objections to Habermas are not applicable when his arguments are properly understood, I go on to suggest ways in which supporters of enhancement might appropriately respond to Habermas' arguments.  相似文献   

4.
Building on research theorizing scale, this article proposes augmentations to existing frameworks that will help illuminate how localities are linked to ‘stranger collectives’ like nations, ethnicities, and global religious ‘communities’. In this case of ethnic revival from Mexico's Sierra Mazateca, people use new vernacular literacy practices tied to local musical performances as a way of ‘customizing’ modular forms deployed by national and global institutions to manage indigenous difference. People ‘re‐imagine’ locality through a localized indigenous literacy that takes templates provided by the Mexican state and the Catholic Church and places them in productive tension with local context: musical properties of the indigenous language Mazatec, locally valued performance practices, and local musical‐linguistic ideologies. While this revival movement draws on immanently modular forms, once locally embedded they become ‘unpiratable’, and constitute a new resource for inscribing local belonging. This case suggests the importance of considering linguistic and musical aspects of social context often taken for granted in anthropological investigations of scale.  相似文献   

5.
Models of isolation‐by‐distance formalize the effects of genetic drift and gene flow in a spatial context where gene dispersal is spatially limited. These models have been used to show that, at an appropriate spatial scale, dispersal parameters can be inferred from the regression of genetic differentiation against geographic distance between sampling locations. This approach is compelling because it is relatively simple and robust and has rather low sampling requirements. In continuous populations, dispersal can be inferred from isolation‐by‐distance patterns using either individuals or groups as sampling units. Intrigued by empirical findings where individual samples seemed to provide more power, we used simulations to compare the performances of the two methods in a range of situations with different dispersal distributions. We found that sampling individuals provide more power in a range of dispersal conditions that is narrow but fits many realistic situations. These situations were characterized not only by the general steepness of isolation‐by‐distance but also by the intrinsic shape of the dispersal kernel. The performances of the two approaches are otherwise similar, suggesting that the choice of a sampling unit is globally less important than other settings such as a study's spatial scale.  相似文献   

6.
To evaluate rates of evolution, to establish tests of correlation between two traits, or to investigate to what degree the phylogeny of a species assemblage is predictive of a trait value so‐called tests for phylogenetic signal are used. Being based on different approaches, these tests are generally thought to possess quite different statistical performances. In this article, we show that the Blomberg et al. K and K*, the Abouheif index, the Moran's I, and the Mantel correlation are all based on a cross‐product statistic, and are thus all related to each other when they are associated to a permutation test of phylogenetic signal. What changes is only the way phylogenetic and trait similarities (or dissimilarities) among the tips of a phylogeny are computed. The definitions of the phylogenetic and trait‐based (dis)similarities among tips thus determines the performance of the tests. We shortly discuss the biological and statistical consequences (in terms of power and type I error of the tests) of the observed relatedness among the statistics that allow tests for phylogenetic signal. Blomberg et al. K* statistic appears as one on the most efficient approaches to test for phylogenetic signal. When branch lengths are not available or not accurate, Abouheif's Cmean statistic is a powerful alternative to K*.  相似文献   

7.
In the period from January 1981 to December 2010, 1068 small‐molecule new chemical entities (NCEs) were introduced, of which ca. 34% are either a natural product or a close analogue. While this metric reflects the impact natural products have played in delivering new chemical starting points (leads) for the pharmaceutical industry, it does not capture the decline this approach has suffered over the last 20 years as the high‐throughput screening (HTS) of pure compound libraries has become more popular. An impediment to natural‐product drug discovery in the HTS paradigm is the lack of a clear strategy that enables front‐loading of an extract or fraction's chemical constituents so that they are compliant with lead‐ and drug‐like chemical space. To address this imbalance, an approach based on lipophilicity, as measured by clog P has been developed that, together with advances being made in isolation and structural elucidation, can afford natural product leads in timelines compatible with pure compound screening.  相似文献   

8.
The sieve tubes of the phloem are enigmatic structures. Their role as channels for the distribution of assimilates was established in the 19th century, but their sensitivity to disturbations has hampered the elucidation of their transport mechanisms and its regulation ever since. Ernst Münch's classical monograph of 1930 is generally regarded as the first coherent theory of phloem transport, but the ‘Münchian’ pressure flow mechanism had been discussed already before the turn of the century. Münch's impact rather rested on his simple physical models of the phloem that visualized pressure flow in an intuitive way, and we argue that the downscaling of such models to realistic, low‐Reynolds‐number sizes will boost our understanding of phloem transport in this century just as Münch's models did in the previous one. However, biologically meaningful physical models that could be used to test predictions of the many existing mathematical models would have to be designed in analogy with natural phloem structures. Unfortunately, the study of phloem anatomy seems in decline, and we still lack basic quantitative data required for evaluating the plausibility of our theoretical deductions. In this review, we provide a subjective overview of unresolved problems in angiosperm phloem structure research within a functional context.  相似文献   

9.
There is growing interest in resolving the curious disconnect between the fields of kin selection and sexual selection. Rankin's (2011, J. Evol. Biol. 24 , 71–81) theoretical study of the impact of kin selection on the evolution of sexual conflict in viscous populations has been particularly valuable in stimulating empirical research in this area. An important goal of that study was to understand the impact of sex‐specific rates of dispersal upon the coevolution of male‐harm and female‐resistance behaviours. But the fitness functions derived in Rankin's study do not flow from his model's assumptions and, in particular, are not consistent with sex‐biased dispersal. Here, we develop new fitness functions that do logically flow from the model's assumptions, to determine the impact of sex‐specific patterns of dispersal on the evolution of sexual conflict. Although Rankin's study suggested that increasing male dispersal always promotes the evolution of male harm and that increasing female dispersal always inhibits the evolution of male harm, we find that the opposite can also be true, depending upon parameter values.  相似文献   

10.
Henslow's Sparrows (Ammodramus henslowii) are known to breed in restored grasslands consisting of either warm‐ or cool‐season grasses, but additional information is needed concerning their breeding biology in these two types of grasslands. We compared the abundance, territory sizes, and pairing success of male Henslow's Sparrows in grasslands in west‐central Missouri in 2010 and 2011 using a paired‐treatment design, where warm‐ and cool‐season grasslands were located in close proximity. Selection indices indicated no apparent preference by male Henslow's Sparrows for either type of grassland, and the territory sizes and pairing success of males in cool‐ and warm‐season grasslands did not differ. In addition, we found no significant differences in habitat structure between these grassland types. Thus, our results suggest that the warm‐ and cool‐season grasslands in our study provided suitable habitat for Henslow's Sparrows. Other investigators have drawn similar conclusions for Henslow's Sparrows and for grassland birds in general, with the structural characteristics and, for some species, the size of grasslands being more important for grassland birds than plant species composition.  相似文献   

11.
Pan1 is a multi‐domain scaffold that enables dynamic interactions with both structural and regulatory components of the endocytic pathway. Pan1 is composed of Eps15 Homology (EH) domains which interact with adaptor proteins, a central region that is responsible for its oligomerization and C‐terminal binding sites for Arp2/3, F‐actin, and type‐I myosin motors. In this study, we have characterized the binding sites between Pan1 and its constitutive binding partner End3, another EH domain containing endocytic protein. The C‐terminal End3 Repeats of End3 associate with the N‐terminal part of Pan1's central coiled‐coil region. These repeats appear to act independently of one another as tandem, redundant binding sites for Pan1. The end3‐1 allele was sequenced, and corresponds to a C‐terminal truncation lacking the End3 Repeats. Mutations of the End3 Repeats highlight that those residues which are identical between these repeats serve as contact sites for the interaction with Pan1.   相似文献   

12.
The globiferous pedicellariae of the venomous sea urchin Toxopneustes pileolus contains several biologically active proteins. We have cloned the cDNA of one of the toxin components, SUL‐I, which is a rhamnose‐binding lectin (RBL) that acts as a mitogen through binding to carbohydrate chains on target cells. Recombinant SUL‐I (rSUL‐I) was produced in Escherichia coli cells, and its carbohydrate‐binding specificity was examined with the glycoconjugate microarray analysis, which suggested that potential target carbohydrate structures are galactose‐terminated N‐glycans. rSUL‐I exhibited mitogenic activity for murine splenocyte cells and toxicity against Vero cells. The three‐dimensional structure of the rSUL‐I/l ‐rhamnose complex was determined by X‐ray crystallographic analysis at a 1.8 Å resolution. The overall structure of rSUL‐I is composed of three distinctive domains with a folding structure similar to those of CSL3, a RBL from chum salmon (Oncorhynchus keta) eggs. The bound l ‐rhamnose molecules are mainly recognized by rSUL‐I through hydrogen bonds between its 2‐, 3‐, and 4‐hydroxy groups and Asp, Asn, and Glu residues in the binding sites, while Tyr and Ser residues participate in the recognition mechanism. It was also inferred that SUL‐I may form a dimer in solution based on the molecular size estimated via dynamic light scattering as well as possible contact regions in its crystal structure.  相似文献   

13.
14.
Since the inception of modern social evolution theory, a vast majority of studies have sought to explain cooperation using relatedness‐driven hypotheses. Natural populations, however, show a substantial amount of variation in social behaviour that is uncorrelated with relatedness. Age offers a major alternative explanation for variation in behaviour that remains unaccounted for. Most natural populations are structured into age‐classes, with ageing being a nearly universal feature of most major taxa, including eukaryotic and prokaryotic organisms. Despite this, the theoretical underpinnings of age‐dependent social behaviour remain limited. Here, I investigate how group age‐composition, demography and life history shape trajectories of age‐dependent behaviours that are expressed conditionally on an actor and recipient's age. I show that demography introduces novel age‐dependent selective pressures acting on social phenotypes. Furthermore, I find that life history traits influence the costs and benefits of cooperation directly, but also indirectly. Life history has a strong impact not only on the genetic structure of the population but also on the distribution of group age‐compositions, with both of these processes influencing the expression of age‐dependent cooperation. Age of peak reproductive performance, in particular, is of chief importance for the evolution of cooperation, as this will largely determine the age and relatedness of social partners. Moreover, my results suggest that later‐life reproductive senescence may occur because of demographic effects alone, which opens new vistas on the evolution of menopause and related phenomena.  相似文献   

15.
Alpha‐synuclein (α‐syn) forms the amyloid‐containing Lewy bodies found in the brain in Parkinson's disease. The neurotransmitter dopamine (DA) reacts with α‐syn to form SDS‐resistant soluble, non‐amyloid, and melanin‐containing oligomers. Their toxicity is debated, as is the nature of their structure and their relation to amyloid‐forming conformers of α‐syn. The small‐angle X‐ray scattering technique in combination with modeling by the ensemble optimization method showed that the un‐reacted native protein populated three broad classes of conformer, while reaction with DA gave a restricted ensemble range suggesting that the rigid melanin molecule played an important part in their structure. We found that 6 M guanidine hydrochloride did not dissociate α‐syn DA‐reacted dimers and trimers, suggesting covalent linkages. The pathological significance of covalent association is that if they are non‐toxic, the oligomers would act as a sink for toxic excess DA and α‐syn; if toxic, their stability could enhance their toxicity. We argue it is essential, therefore, to resolve the question of whether they are toxic or not. Proteins 2014; 82:10–21. © 2013 Wiley Periodicals, Inc.  相似文献   

16.
Joona Räsänen 《Bioethics》2016,30(9):656-662
Alberto Giubilini and Francesca Minerva's controversial article ‘After‐Birth Abortion: Why Should the Baby Live?’ has received a lot of criticism since its publishing. Part of the recent criticism has been made by pro‐life philosopher Christopher Kaczor, who argues against infanticide in his updated book ‘Ethics of Abortion’. Kaczor makes four arguments to show where Giubilini and Minerva's argument for permitting infanticide goes wrong. In this article I argue that Kaczor's arguments, and some similar arguments presented by other philosophers, are mistaken and cannot show Giubilini and Minerva's view to be flawed. I claim that if one wants to reject the permissibility of infanticide, one must find better arguments for doing so.  相似文献   

17.
Zebras, as prey species, attend to the behavior of nearby conspecifics and heterospecifics when making decisions to flee from predators. Plains zebras (Equus quagga) and Grevy's zebras (E. grevyi) frequently form mixed‐species groups in zones where their ranges overlap in Kenya. Although anecdotal observations suggest that Plains zebras are more flighty around humans than Grevy's zebras are, this has not been empirically confirmed, and relatively little is known about how they may influence each other's flight behavior. We addressed these questions by examining the flight initiation distances (FIDs) of Plains and Grevy's zebras in single‐species and mixed‐species groups from an approaching human. One target individual per group was approached steadily on foot, with start distance, alert distance, and FID recorded from this target. Using start distance and alert distance separately as covariates, 22 Plains zebras in single‐species groups exhibited a significantly longer mean FID than 15 Grevy's zebras in single‐species groups. The FIDs of 7 Plains zebras and 5 Grevy's zebras tested in mixed‐species groups were virtually equivalent and intermediate to those of Plains and Grevy's zebras in single‐species groups, suggesting a bidirectional moderating influence of heterospecifics on risk assessment. This effect was most pronounced for Plains zebras in mixed‐species groups that exhibited an FID that was significantly shorter than that of Plains zebras in single‐species groups. Our findings underscore the importance of recognizing that related equids may be differently impacted by anthropogenic stress.  相似文献   

18.
Hsp90 is an essential chaperone that requires large allosteric changes to determine its ATPase activity and client binding. The co‐chaperone Aha1, which is the major ATPase stimulator in eukaryotes, is important for regulation of Hsp90's allosteric timing. Little is known, however, about the structure of the Hsp90/Aha1 complex. Here, we characterize the solution structure of unmodified human Hsp90/Aha1 complex using NMR spectroscopy. We show that the 214‐kDa complex forms by a two‐step binding mechanism and adopts multiple conformations in the absence of nucleotide. Aha1 induces structural changes near Hsp90's nucleotide‐binding site, providing a basis for its ATPase‐enhancing activity. Our data reveal important aspects of this pivotal chaperone/co‐chaperone interaction and emphasize the relevance of characterizing dynamic chaperone structures in solution.  相似文献   

19.
The COVID‐2019 pandemic is the most severe acute public health threat of the twenty‐first century. To properly address this crisis with both robust testing and novel treatments, we require a deep understanding of the life cycle of the causative agent, the SARS‐CoV‐2 coronavirus. Here, we examine the architecture and self‐assembly properties of the SARS‐CoV‐2 nucleocapsid protein, which packages viral RNA into new virions. We determined a 1.4 Å resolution crystal structure of this protein's N2b domain, revealing a compact, intertwined dimer similar to that of related coronaviruses including SARS‐CoV. While the N2b domain forms a dimer in solution, addition of the C‐terminal spacer B/N3 domain mediates formation of a homotetramer. Using hydrogen‐deuterium exchange mass spectrometry, we find evidence that at least part of this putatively disordered domain is structured, potentially forming an α‐helix that self‐associates and cooperates with the N2b domain to mediate tetramer formation. Finally, we map the locations of amino acid substitutions in the N protein from over 38,000 SARS‐CoV‐2 genome sequences. We find that these substitutions are strongly clustered in the protein's N2a linker domain, and that substitutions within the N1b and N2b domains cluster away from their functional RNA binding and dimerization interfaces. Overall, this work reveals the architecture and self‐assembly properties of a key protein in the SARS‐CoV‐2 life cycle, with implications for both drug design and antibody‐based testing.  相似文献   

20.
Kemalism in Turkey is often presented as an exemplary case of paternalistic and authoritarian modernisation from above, and lauded or condemned for that very reason. Represented in these terms, certain analytic and political binaries are also activated: state versus society; world‐view versus life‐world; universality versus particularity; inauthenticity versus indigeneity; homogeneity versus heterogeneity/resistance. By contrast, in this paper I seek to sidestep these organising categories to focus on Kemalism and Islamism as rival forms of the same social imaginary signification, and not as shorthand for these polarities. Using a number of representative texts, I argue that the extravagance of Islamist resistance in Turkey post‐1980 brings to light the fantastical power of Kemalism itself, exposed as a project of the triumph of the will. This being the case, what has been written in anthropology about acts of ‘self‐institution’? The work of Nigel Rapport and Cornelius Castoriadis emphasises, in different ways, the arbitrariness and gratuity of social creation out of nothing or self‐institution. Pierre Bourdieu's work, on the other hand, is radically contrary to Rapport's in its structuralist elaboration of agency as guided action. My analysis of processes of change within both the Islamist and Republican social movements in Turkey from the early 1990s to the present seeks a temporary rapprochement, at least in this case, between Rapport's methodological individualism and Bourdieu's methodological holism.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号