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1.
Because of a change at a hospital, we are able to contrast two different structures of leadership in a union worksite. Since we had tested a cognitive construct we call "union consciousness" before the change, the difference in structure provides a natural experiment to determine the consequences of structural change for cognition. We repeated the test after the change and found a different cognitive structure. We conclude that cognitive structures are not enduring configurations but that they change as structures change. This leads to the further conclusion that external structures are powerful determinants of patterns of thought, [ experiment, cognition, structure, organized labor, unions, healthcare, culture, theory ]  相似文献   

2.
As Arabidopsis thaliana is increasingly employed in evolutionary and ecological studies, it is essential to understand patterns of natural genetic variation and the forces that shape them. Previous work focusing mostly on global and regional scales has demonstrated the importance of historical events such as long-distance migration and colonization. Far less is known about the role of contemporary factors or environmental heterogeneity in generating diversity patterns at local scales. We sampled 1,005 individuals from 77 closely spaced stands in diverse settings around Tübingen, Germany. A set of 436 SNP markers was used to characterize genome-wide patterns of relatedness and recombination. Neighboring genotypes often shared mosaic blocks of alternating marker identity and divergence. We detected recent outcrossing as well as stretches of residual heterozygosity in largely homozygous recombinants. As has been observed for several other selfing species, there was considerable heterogeneity among sites in diversity and outcrossing, with rural stands exhibiting greater diversity and heterozygosity than urban stands. Fine-scale spatial structure was evident as well. Within stands, spatial structure correlated negatively with observed heterozygosity, suggesting that the high homozygosity of natural A. thaliana may be partially attributable to nearest-neighbor mating of related individuals. The large number of markers and extensive local sampling employed here afforded unusual power to characterize local genetic patterns. Contemporary processes such as ongoing outcrossing play an important role in determining distribution of genetic diversity at this scale. Local “outcrossing hotspots” appear to reshuffle genetic information at surprising rates, while other stands contribute comparatively little. Our findings have important implications for sampling and interpreting diversity among A. thaliana accessions.  相似文献   

3.
Ethnobotanical studies often assume plant knowledge is shared by all members of an arbitrarily bounded human group. By describing the uses and local categorization of plants in one village in rural Panama in a heteroglossic approach, the different knowledges within a village are presented in one article. Plants used in the daily work of women and men, and the work of village spe-cialists are described. Villagers negotiate changing realities by adapting plant use and knowl-edge; this is reflected in local categorization of plant names into antes and hoy dia. Unlike the established ethnobotanical assumption that bounded units of plant knowledge are dying, the younger generations of villagers, who work both within and outside the village, know more plants useful to their changing economic opportunities. Subsistence agriculturalists possess the adaptive plant knowledge skills to be stewards of the environment.  相似文献   

4.
Geographic range, turnover rate and the scaling of species diversity   总被引:6,自引:0,他引:6  
The study of the relative roles of local and regional processes in determining the scaling of species diversity is a very active field in current ecology. The importance of species turnover and the species‐range‐size frequency distributions in determining how local and regional species diversity are linked has been recognised by recent approaches. Here we present a model, based on a system of fully nested sampling quadrats, to analyse species diversity at several scales. Using a recursive procedure that incorporates increasingly smaller scales and a multiplicative formula for relating local and regional diversity, the model allows the simultaneous depiction of alpha, beta and gamma diversity in a single “species‐scale plot”. Species diversity is defined as the number of ranges that are intersected by sampling quadrats of various sizes. The size, shape and location of individual species ranges determine diversity at any scale, but the average point diversity, measured at hypothetical zero‐area localities, is determined solely by the size of individual ranges, regardless of their shape and location. The model predicts that if the species‐area relationship is a power function, then beta diversity must be scale invariant if measured at constant scale increments. Applying the model to the mammal fauna of four Mexican regions with contrasting environmental conditions, we found that: 1) the species‐range‐size frequency distribution at the scale of the Mexican regions differs from the log‐normal pattern reported for the national and continental scales. 2) Beta diversity is not scale‐invariant within each region, implying that the species‐area relationship (SAR) does not follow a power function. 3) There is geographic variation in beta diversity. 4) The scaling of diversity is directly linked to patterns of species turnover rate, and ultimately determined by patterns in the geographic distribution of species. The model shows that regional species diversity and the average distribution range of species are the two basic data necessary to predict patterns in the scaling of species diversity.  相似文献   

5.
Lu M  Ma J 《Biophysical journal》2005,89(4):2395-2401
We examined the role of molecular shape in determining the patterns of low-frequency deformational motions of biological macromolecules. The low-frequency subspace of eigenvectors in normal mode analysis was found to be robustly similar upon randomization of the Hessian matrix elements as long as the structure of the matrix is maintained, which indicates that the global shape of molecules plays a more dominant role in determining the highly anisotropic low-frequency motions than the absolute values of stiffness and directionality of local interactions. The results provided a quantitative foundation for the validity of elastic normal mode analysis.  相似文献   

6.
Empirical population genetic studies have been dominated by a neutralist view, according to which gene flow and drift are the main forces driving population genetic structure in nature. The neutralist view in essence describes a process of isolation by dispersal limitation (IBDL) that generally leads to a pattern of isolation by distance (IBD). Recently, however, conceptual frameworks have been put forward that view local genetic adaptation as an important driver of population genetic structure. Isolation by adaptation (IBA) and monopolization (M) posit that gene flow among natural populations is reduced as a consequence of local genetic adaptation. IBA stresses that effective gene flow is reduced among habitats that show dissimilar ecological characteristics, leading to a pattern of isolation by environment. In monopolization, local genetic adaptation of initial colonizing genotypes results in a reduction in gene flow that fosters the persistence of founder effects. Here, we relate these different processes driving landscape genetic structure to patterns of IBD and isolation by environment (IBE). We propose a method to detect whether IBDL, IBA and M shape genetic differentiation in natural landscapes by studying patterns of variation at neutral and non‐neutral markers as well as at ecologically relevant traits. Finally, we reinterpret a representative number of studies from the recent literature by associating patterns to processes and identify patterns associated with local genetic adaptation to be as common as IBDL in structuring regional genetic variation of populations in the wild. Our results point to the importance of quantifying environmental gradients and incorporating ecology in the analysis of population genetics.  相似文献   

7.
We describe the spatial pattern of variation in body size, body shape, and adult population age structure of the Italian treefrog (Hyla intermedia). By means of a non-parametric test of matrix association (the Partial Mantel Test), we investigate the role of climate and geography in explaining the patterns of phenotypic variation. Body size is the most important source of morphometric variation, both at intra- and inter-populational levels. Body shape, despite its secondary role in explaining variation, still maintains high discriminative power among populations. Age structure differs significantly among populations, since body size correlates positively to age, these differences partly explain geographic variation of body size. The patterns of variation in both age and body size are congruent with climate variation, suggesting causal relationship. However, we find no evidence for adaptive explanations and suggest that climate-induced demographically differential survivorship might be the proximate cause responsible for the associations observed. Unlike body size, body shape varies congruently with the pattern of between-population geographic distances, which we show to be highly correlated with their genetic distances, thus suggesting isolation by distance as the proximate cause of the association.  相似文献   

8.
Using a cultural studies approach, this study situates three young adolescents in their home, neighborhood, school, and peer cultures, and contextually analyzes their uses and interpretations of television. Analyses of each student's favorite television persona illuminate each of their identity projects, which are a primary kind of cultural acquisition process. I find qualitative differences in their everyday learning within television culture as compared to local cultures, although their learning about social power across cultures is reciprocal.  相似文献   

9.
Species may cope with rapid habitat changes by distribution shifts or adaptation to new conditions. A common feature of these responses is that they depend on how the process of dispersal connects populations, both demographically and genetically. We analyzed the genetic structure of a near-threatened high-Arctic seabird, the ivory gull (Pagophila eburnea) in order to infer the connectivity among gull colonies. We analyzed 343 individuals sampled from 16 localities across the circumpolar breeding range of ivory gulls, from northern Russia to the Canadian Arctic. To explore the roles of natal and breeding dispersal, we developed a population genetic model to relate dispersal behavior to the observed genetic structure of worldwide ivory gull populations. Our key finding is the striking genetic homogeneity of ivory gulls across their entire distribution range. The lack of population genetic structure found among colonies, in tandem with independent evidence of movement among colonies, suggests that ongoing effective dispersal is occurring across the Arctic Region. Our results contradict the dispersal patterns generally observed in seabirds where species movement capabilities are often not indicative of dispersal patterns. Model predictions show how natal and breeding dispersal may combine to shape the genetic homogeneity among ivory gull colonies separated by up to 2800 km. Although field data will be key to determine the role of dispersal for the demography of local colonies and refine the respective impacts of natal versus breeding dispersal, conservation planning needs to consider ivory gulls as a genetically homogeneous, Arctic-wide metapopulation effectively connected through dispersal.  相似文献   

10.
Rural Youth and Youth Culture in North China   总被引:2,自引:0,他引:2  
This article describes how economic reforms have transformed the local world of village life in North China, specifically the emergence of a rural youth culture that reflects urban values and styles. This culture has both challenged and enriched rural China's tradition and its more recent communal structure, a change that reshapes the relations amongst family members of different age cohorts as well as between peasants and cadres. it is argued that this transformation in the Chinese countryside holds opportunities to improve living conditions and unmake the constraints of tradition and the modern nation-state on life chances and everyday experience. The sheer number of rural youth in China suggests that the future impact of this transformation on social realities could be enormous.  相似文献   

11.
Bhats are low-status bards from the Indian state of Rajasthan. This paper explores a Bhat puppet drama sponsored by a state-run bank meant to teach Indians an ethic of saving and planning for the future. Specifically, it examines the manner in which Bhats sabotage their work for the bank, mocking the values they are hired to promote and thus ‘resisting’ modernist ideologies that purportedly allow for the rational management of time. Still, Bhat dramas are not only conventional political weapons that turn the world upside-down, but also poetic devices that potentially raise the consciousness of audience members so that they themselves might resist. In fact, this play, in the manner it speaks truth to power and thus teaches others to resist in thought or action, resembles the Bhats' traditional praise-work for their formerly Untouchable patrons. I therefore suggest that the Bhats' ‘subaltern consciousness,’ like their insights into the discursive construction of modern authority, is tightly intertwined with local performance traditions.  相似文献   

12.
W Feldman  R Milner  N Punthakee 《CMAJ》1980,123(3):185-189
A nationwide survey of Canadian pediatricians was undertaken to answer questions about demographic and practice characteristics, perceptions of the quantity and quality of residency training in relation to the realities of practice, and the patterns of use and the value of continuing medical education. The findings included a lower average age of pediatricians from that determined 10 years earlier, a higher proportion of women practising pediatrics, and higher proportions of pediatricians entering practice in smaller communities, doing geographic full-time university work and doing mainly consulting work. Pediatrics is still perceived as an attractive discipline, but there is dissatisfaction with the quantity and quality of training in adolescent medicine, ophthalmology, dermatology, psychosocial pediatrics and orthopedics. The changing patterns of continuing medical education among the most recent certificants suggest a need for journals and professional societies to assess how they can better meet the needs of Canadian pediatricians in this area.  相似文献   

13.
Evan P. Economo  Timothy H. Keitt 《Oikos》2010,119(8):1355-1363
Biologists seek an understanding of the biological and environmental factors determining local community diversity. Recent advances in metacommunity ecology, and neutral theory in particular, highlight the importance of dispersal processes interacting with the spatial structure of a landscape for generating spatial patterns and maintaining biodiversity. The relative spatial isolation of a community is traditionally thought to have a large influence on local diversity. However, isolation remains an elusive concept to quantify, particularly in metacommunities with complex spatial structure. We represent the metacommunity as a network of local communities, and use network centrality measures to quantify the isolation of a local community. Using spatially explicit neutral theory, we examine how node position predicts variation in alpha diversity across a metacommunity. We find that diversity increases with node centrality in the network, but only when centrality is measured on a given scale in the network that widens with increasing dispersal rates and narrows with increasing evolutionary rates. More generally, complex biodiversity patterns form only when the underlying geography has structure on this critical scale. This provides a framework for understanding the influence of spatial geographic structure on global biodiversity patterns.  相似文献   

14.
A central issue in socioecology is the nature of the relationship between an organism's environment and its social structure. In chimpanzees, the fission-fusion social system is thought to minimize feeding competition for primary dietary components: ephemeral, dispersed patches of ripe fruit. Intragroup feeding competition is thought to force individuals into small parties. Informal observations in the Sonso region of the Budongo forest had suggested that in this habitat, food supply was such that feeding competition was less important in determining grouping patterns than elsewhere. We used data collected on food supply and party sizes over a 4-year period to investigate this suggestion. In accord with theoretical expectation, sizes of foraging parties fluctuated with the size of food patches. However, party sizes showed either negative or no relationship with habitat-wide measures of food abundance. Likewise party sizes showed little relationship to overall measures of food dispersion. For important dietary items, both fruit and leaves had patchy distributions, though the degree of clumping was not strong, and fruit was not more clumped than leaves. Generally, abundant food appeared to be less patchy, and chimpanzees appeared to use more patches as food became more abundant rather than forming larger parties. We suggest that both dispersal and abundance need to be considered when investigating the impact of food supply on grouping patterns, and that the importance of food as a factor in determining chimpanzee grouping patterns declines with increasing levels of abundance.  相似文献   

15.
As Myanmar undergoes political and societal transition, observers are asking questions about citizenship and ethnic identity. How does one think about citizenship and people's negotiations with law in political-legal regimes that do not subscribe to liberal democratic norms? This paper investigates how law marginalizes the Burmese Chinese minority in Myanmar and the nature of their legal participation. Since law asserts cultural power impacting the way people think and behave, we engage with the concept of legal consciousness to understand how perceptions of legal vulnerability shape political subjectivity ambivalently. The paper highlights the spatial strategies and everyday practices that the Burmese Chinese deploy to navigate oppressive laws, but signals that internal social divisions and geopolitical considerations deter collective action towards rights assertion. It argues that studying the multiple sites and scales through which law is engaged contributes towards recovering citizenship aspirations where engagement with power and authority are articulated differently from Western norms.  相似文献   

16.
Community studies as a form of study in complex societies cart be unduly restrictive though this need not be the case. It depends on the criteria employed to select a field location, and on the types of social organization studied within that location. These themes are illustrated by reference to the Australian community studies of Ron Wild and Harry Oxley. Some limitations in their studies are noted only in order to illustrate how their work might have been linked profitably with debates in Australian historiography over issues of class culture, ideology and consciousness. I propose a framework for Australian community studies that would allow anthropologists to explore some of the themes introduced in this discussion.  相似文献   

17.
In the traditionalist villages of south Pentecost, kastom has long been a bulwark against European influences, both Christian and secular. However, their retention of the famous gol land dive ritual has brought the south Pentecost people under pressure from tourism, whose great allure masks the risks of a rise of kastom as commodity, packaged for sale, and of the erosion of kasfom's centrality as living practice. Pressures to conform to a pure kastom (i.e. unadulterated by any non-indigenous elements) distort the realities of a dynamic kastom that has long incorporated useful elements of alien material culture into everyday living.  相似文献   

18.
Amino acid sequence patterns suggested to characterize specific recurrent turn conformation in protein are tested as to their predictive power in a database containing 75 proteins of known structure. Many of these patterns are found to be associated with local structures that differ from the motifs originally used to derive them. It is therefore concluded that, while they could be useful for improving predictions made by other methods, their stand-alone predictive power is poor. The issue of deriving and validating consensus sequence patterns for use in protein structure prediction is raised.  相似文献   

19.
20.
Li MS 《Biophysical journal》2007,93(8):2644-2654
It is well known that the unfolding times of proteins, tauu, scales with the external mechanical force f as tauu=tauu0exp(-fxu/kBT), where xu is the location of the average transition state along the reaction coordinate given by the end-to-end distance. Using the off-lattice Go-like models, we have shown that in terms of xu, proteins may be divided into two classes. The first class, which includes beta- and beta/alpha-proteins, has xu approximately 2-5 A whereas the second class of alpha-proteins has xu about three times larger than that of the first class, xu approximately 7-15 A. These results are in good agreement with the experimental data. The secondary structure is found to play the key role in determining the shape of the free energy landscape. Namely, the distance between the native state and the transition state depends on the helix content linearly. It is shown that xu has a strong correlation with mechanical stability of proteins. Defining the unfolding force, fu, from the constant velocity pulling measurements as a measure of the mechanical stability, we predict that xu decays with fu by a power law, xu approximately fu(-mu), where the exponent mu is approximately 0.4. We have demonstrated that the unfolding force correlates with the helix content of a protein. The contact order, which is a measure of fraction of local contacts, was found to strongly correlate with the mechanical stability and the distance between the transition state and native state. Our study reveals that xu and fu might be estimated using either the helicity or the contact order.  相似文献   

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