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1.
Sally Engle Merry 《Ethnos》2013,78(3-4):157-175
Gender must be understood as a domain of social practice with its own structure and dynamics. An outline of a relational account of gender is given, emphasizing the multiple structures of gender and the way bodies are drawn into social practice. Emerging research on masculinity can best be understood through such an approach, which allows the multiplicity of masculinities, and their interrelations, to be traced. Two case studies are outlined: theoretical work on the relations between masculinities and state institutions, and field research on working‐class masculinities under structural unemployment.  相似文献   

2.
Coevolution—reciprocal evolutionary change among interacting species driven by natural selection—is thought to be an important force in shaping biodiversity. This ongoing process takes place within tangled networks of species interactions. In microbial communities, evolutionary change between hosts and parasites occurs at the same time scale as ecological change. Yet, we still lack experimental evidence of the role of coevolution in driving changes in the structure of such species interaction networks. Filling this gap is important because network structure influences community persistence through indirect effects. Here, we quantified experimentally to what extent coevolutionary dynamics lead to contrasting patterns in the architecture of bacteria–phage infection networks. Specifically, we look at the tendency of these networks to be organized in a nested pattern by which the more specialist phages tend to infect only a proper subset of those bacteria infected by the most generalist phages. We found that interactions between coevolving bacteria and phages become less nested over time under fluctuating dynamics, and more nested under arms race dynamics. Moreover, when coevolution results in high average infectivity, phages and bacteria differ more from each other over time under arms race dynamics than under fluctuating dynamics. The tradeoff between the fitness benefits of evolving resistance/infectivity traits and the costs of maintaining them might explain these differences in network structure. Our study shows that the interaction pattern between bacteria and phages at the community level depends on the way coevolution unfolds.  相似文献   

3.
Symbols and dynamics in the brain   总被引:2,自引:0,他引:2  
Cariani P 《Bio Systems》2001,60(1-3):59-83
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4.
The dynamics of individual DNA molecules in a thin gel were studied with fluorescence microscopy. Driven by an electric field, molecules hooked around isolated obstacles and became extended. By analyzing molecular images, we identified the reptation tube and primitive chain. When the field was turned off, the molecules relaxed. The relaxation time tau1 and primitive chain length at equilibrium depend on N, the size of the molecule in base pairs, consistently with reptation theory. Using five yeast chromosomal DNAs ranging in size from 245 kb to 980 kb, we found that: These results constitute a way of sizing individual DNA molecules by imaging rather than by gel electrophoresis.  相似文献   

5.
The resolution of the June 1983 Plenum of the Central Committee of the CPSU "Current problems in ideological mass political work of the Party" points out the necessity of "raising the level of educational work in schools and teachers' training institutions, systematic pursuit of Leninist principles in comprehensive labor and polytechnical schools, inculcating in pupils the habits and love of socially useful work, expanding their ideological horizons, and shaping in each and every one of them the high qualities of a citizen of socialist society and an active builder of communism" [2. P. 78].  相似文献   

6.
Juvenile hormone (JH) has an important role in the behavior of eusocial Hymenoptera. Previous work has shown that JH influences aggression and dominance behavior in primitive eusocial insects that lack discrete queen and worker castes (e.g. Bombus bees and Polistes wasps). In contrast, JH is one of the factors that mediates temporal polyethism among workers in advanced eusocial insects that have reproductive castes (e.g. Apis bees and Polybiawasps). Therefore, initial observations suggest that JH may have different roles in primitive and advanced eusocial taxa. Here, we use detailed behavioral observations of marked individuals to test whether JH influences temporal polyethism in the primitive eusocial wasp Polistes dominulus. First, we show that workers in P. dominulus have an age-related division of labor, as workers switch from nest work to foraging as they mature. Then, we show that application of JH accelerates the onset of foraging behavior.Workers treated with JH start foraging at a younger age than control workers. Therefore, JH mediates temporal polyethism in the primitively eusocial insect Polistes dominulus. Received 23 April 2008; revised 6 August 2008; accepted 11 August 2008  相似文献   

7.
《Biophysical journal》2021,120(21):4722-4737
In this work, we propose a generalized Langevin equation-based model to describe the lateral diffusion of a protein in a lipid bilayer. The memory kernel is represented in terms of a viscous (instantaneous) and an elastic (noninstantaneous) component modeled through a Dirac δ function and a three-parameter Mittag-Leffler type function, respectively. By imposing a specific relationship between the parameters of the three-parameter Mittag-Leffler function, the different dynamical regimes—namely ballistic, subdiffusive, and Brownian, as well as the crossover from one regime to another—are retrieved. Within this approach, the transition time from the ballistic to the subdiffusive regime and the spectrum of relaxation times underlying the transition from the subdiffusive to the Brownian regime are given. The reliability of the model is tested by comparing the mean-square displacement derived in the framework of this model and the mean-square displacement of a protein diffusing in a membrane calculated through molecular dynamics simulations.  相似文献   

8.
Abstract. Scientific progress in plant ecology is at risk of being obscured by increasing ignorance of major works in the field. The driving force seems to be the twin seductions of novelty and crowd psychology. I illustrate this tendency with three examples from plant community ecology that span the past thirty years of ecological research. I offer, as one solution, the concept of a canon: a short list of essential books that we assume all students and co‐workers have read, a short list that summarizes the wisdom of the discipline. A canon can be likened to DNA, be it in music, art, or science, as it carries forward through time the key ideas that have worked in the past. Without a canon, there is no memory of past achievement, no context for appreciating current work, and no way of judging the quality of newer productions. I suggest 20 essential books (the short canon), and 22 complementary readings, for a total of 42 books needed in any young professional's library on plant ecology.  相似文献   

9.
This paper discusses the recent rise of popular ‘blockbuster’ books written by international development industry insiders and produced by commercial publishers. The paper explores a set of common stylistic devices found within this emerging genre. Though each book is different, a key trope is the story of an author's earlier professional life—the hard lessons and gritty insights that have supposedly emerged from it—that normally underpins each narrative. By living the challenges involved in development work at first hand, and by making mistakes and experiencing epiphanies along the way, these author-professionals want readers to know that they have found out the hard way that long-cherished beliefs about development now need to be questioned. Readers are invited to relive these lessons and epiphanies, and to think and act differently about development by upholding a highly pragmatic form of development professionalism. Combining elements of research monograph, self-help book and personal memoir, these development blockbuster books can be understood not only as commodities, but also as part of the development gift. The authors promise a gift of experience but, in reality, these books are mundane commodities enmeshed in capitalist exchange relations.  相似文献   

10.
Animal husbandry and working conditions for livestock farmers have changed significantly in recent years as agriculture has been exposed to economic as well as health, environmental and ethical challenges. The idea of interdependent welfare between humans and animals is more relevant now than ever. Here, we innovatively bridge two disciplines—ergonomics and applied ethology—to achieve an in-depth observational understanding of real husbandry practice (by farmers, inseminators, vets) at work. Ergonomics aims to gain a detailed understanding of human activity in its physical, sensitive and cognitive dimensions in relation to a task. It also aims to transform work situations through a systemic approach drawing on multiple levers for change. Here, we examine how this analysis holds up to the inclusion of animals as an integral component of the livestock farmer’s work situation. Applied ethology studies behaviours in animals managed by humans. It aims to understand how these animals perceive their environment, including how they construct their relationship with the livestock farmer. This paper proposes an original conception of the human–animal relationship in animal husbandry that employs core structural concepts from both disciplines. From an ergonomic point of view, we address the human–animal relations by examining the relationship between ‘prescribed’ and real work practices, between work and personal life situation, between professional task and human activity. On the applied ethology side of the equation, the human–animal relationship is a process built through communication and regular interactions between two ‘partners’ who know each other. The goal is to understand how each partner perceives the other according to their multimodal sensory world and their cognitive and emotional capacities, and to predict the outcome of future interactions. We cross-analyse these scientific views to show, based on examples, how and in what way they can intersect to bring better analysis of these human–animal relationships. We reflect on common working hypotheses and situated observational approaches based on indicators (behaviour and animal and human welfare/health). This analysis prompts us to clarify what human–animal relational practice means in animal husbandry work, i.e. a strategy employed by the livestock farmer to work safely and efficiently in a healthy environment, where the animal is treated as a partner in the relationship. In this perspective, the challenge is for the livestock farmer’s activity to co-build a positive relationship and avoid being subject to this one.  相似文献   

11.
Advances in medical imaging and image processing are paving the way for personalised cardiac biomechanical modelling. Models provide the capacity to relate kinematics to dynamics and—through patient-specific modelling—derived material parameters to underlying cardiac muscle pathologies. However, for clinical utility to be achieved, model-based analyses mandate robust model selection and parameterisation. In this paper, we introduce a patient-specific biomechanical model for the left ventricle aiming to balance model fidelity with parameter identifiability. Using non-invasive data and common clinical surrogates, we illustrate unique identifiability of passive and active parameters over the full cardiac cycle. Identifiability and accuracy of the estimates in the presence of controlled noise are verified with a number of in silico datasets. Unique parametrisation is then obtained for three datasets acquired in vivo. The model predictions show good agreement with the data extracted from the images providing a pipeline for personalised biomechanical analysis.  相似文献   

12.
Guang Song 《Proteins》2017,85(9):1741-1758
In PDB, more than half of the entries are structure complexes and of these complexes, most are symmetric, composed of identical subunits. Complex formation is the way through which larger structures and even molecular machines are assembled and built in nature. In this work, we apply group theory and carry out a comprehensive study of the global motion patterns of protein complexes of various symmetries. The work presents for the first time a comprehensive list of all the symmetric, aesthetically pleasing, global motion patterns available to complexes of cyclic, dihedral, tetrahedral, or octahedral symmetry. Our results clearly demonstrate that complexes with the same symmetry will have the same global motion patterns and thus may function in a similar way, and that there are only a finite number of global motion patterns available to symmetric complexes as the number of protein symmetry groups is effectively finite. The work complements our current understanding of the principle of complex formation that has been mostly structure‐based by providing novel dynamics‐based insights. Furthermore, as dynamics is closely tied to function, these motion patterns can provide global insights into the general functional mechanisms of protein complexes.  相似文献   

13.
Idan Breier 《Anthrozo?s》2013,26(6):657-672
ABSTRACT

This paper examines the relations between humans and wild animals in the lands of the Bible and ancient Near East and the way in which these cultures used various creatures and their characteristics as metaphors for dangerous enemies. It focuses on three particular periods in which the sources at our disposal document human–wild animal interactions. The first section discusses the emergence of civilization in Mesopotamia as reflected in various texts, discussing their portrait of the epoch in which human culture took shape and domesticated animals began to be clearly differentiated from wild ones. The second part looks at human–canine relations—wild dogs and their domesticated counterparts—briefly surveying how the former serve as metaphors for enemies beyond inhabited regions as evinced in the Egyptian El-Amarna archive. The third section analyzes the human–animal relations portrayed in the biblical texts, reviewing the theological principles they adopt in relation to the animal kingdom and the way in which wild animals became a metaphor for both wicked adversaries and striking physical attributes.  相似文献   

14.
The mutation rate of an organism is itself evolvable. In stable environments, if faithful replication is costless, theory predicts that mutation rates will evolve to zero. However, positive mutation rates can evolve in novel or fluctuating environments, as analytical and empirical studies have shown. Previous work on this question has focused on environments that fluctuate independently of the evolving population. Here we consider fluctuations that arise from frequency-dependent selection in the evolving population itself. We investigate how the dynamics of competing traits can induce selective pressure on the rates of mutation between these traits. To address this question, we introduce a theoretical framework combining replicator dynamics and adaptive dynamics. We suppose that changes in mutation rates are rare, compared to changes in the traits under direct selection, so that the expected evolutionary trajectories of mutation rates can be obtained from analysis of pairwise competition between strains of different rates. Depending on the nature of frequency-dependent trait dynamics, we demonstrate three possible outcomes of this competition. First, if trait frequencies are at a mutation–selection equilibrium, lower mutation rates can displace higher ones. Second, if trait dynamics converge to a heteroclinic cycle—arising, for example, from “rock-paper-scissors” interactions—mutator strains succeed against non-mutators. Third, in cases where selection alone maintains all traits at positive frequencies, zero and nonzero mutation rates can coexist indefinitely. Our second result suggests that relatively high mutation rates may be observed for traits subject to cyclical frequency-dependent dynamics.  相似文献   

15.

We discuss the management of trees and forests through the lens of “landesque capital.” A theoretical point of departure is how landesque capital accumulates through a process that relies on both the ‘work of nature’ and the ‘work of people.’ This approach highlights the importance of undertaking a critical analysis of labor investment and its landscape legacies in relation to ecological processes, social dynamics, and political economy. Empirically we draw on the case of smallholder production of coffee and annual crops in southwestern Ethiopia. We show how both the production (generation and maintenance) and destruction of forests in the study area are largely shaped by processes of landesque capital accumulation and discuss the importance of analyzing how people contribute to produce forests to meet production goals in contrast to the ubiquitous notion of humans as a solely destructive force of change in forest ecosystems.

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16.
Dispersal—the movement of an individual from the site of birth to a different site for reproduction—is an ecological and evolutionary driver of species ranges that shapes patterns of colonization, connectivity, gene flow, and adaptation. In plants, the traits that influence dispersal often vary within and among species, are heritable, and evolve in response to the fitness consequences of moving through heterogeneous landscapes. Spatial and temporal variation in the quality and quantity of habitat are important sources of selection on dispersal strategies across species ranges. While recent reviews have evaluated the interactions between spatial variation in habitat and dispersal dynamics, the extent to which geographic variation in temporal variability can also shape range-wide patterns in dispersal traits has not been synthesized. In this paper, we summarize key predictions from metapopulation models that evaluate how dispersal evolves in response to spatial and temporal habitat variability. Next, we compile empirical data that quantify temporal variability in plant demography and patterns of dispersal trait variation across species ranges to evaluate the hypothesis that higher temporal variability favors increased dispersal at plant range limits. We found some suggestive evidence supporting this hypothesis while more generally identifying a major gap in empirical work evaluating plant metapopulation dynamics across species ranges and geographic variation in dispersal traits. To address this gap, we propose several future research directions that would advance our understanding of the interplay between spatiotemporal variability and dispersal trait variation in shaping the dynamics of current and future species ranges.  相似文献   

17.
To compare the social structure of primitively social wasps with that of communal breeding vertebrates, we used a new technique based on micro videocameras applied to the nest envelope to study the organization of behavior in Malaysian colonies of the stenogastrine wasp Eustenogaster fraterna. The reproductive division of labor in this species appears to be different from that reported so far in other species of Stenogastrinae: it is at a very primitive stage because the helpers work less hard and take fewer risks than the egg-layers. Nevertheless, the very low-risk tasks performed by the helpers (nest guarding and supply of abdominal secretion to the young larvae) are important for the colonies. Behavioral characters and ovarian development of the helpers suggest that females are only temporary helpers and that they wait to start their own production of offspring in the hope of inheriting the nest. Females of the same colony can be highly related, but in some colonies we found low-related individuals. The social organization of these wasps resembles that of vertebrate groups with helpers at the den, i.e., in the small number of individuals, the division of labor with limited reproductive inhibition, and the prolonged external work of the reproductive individuals. However, the main drive to sociality in these insects appears to be different, being based mainly on problems connected with short adult life and long immature brood development.  相似文献   

18.
Across cultures, women tend to marry older men. This phenomenon is commonly described as the result of evolved mate choice preferences, which cause men to base reproductive decisions on cues of youth and fertility in women, and women to base such decisions on cues of wealth and status in men. Other researchers have challenged this idea, arguing that husband-older spousal age-gaps might not be consistent with the joint preferences of men and women; age-gaps might instead arise as the result of sexual conflict. In such cases, the realized age-gap could benefit one party at a cost to the other. In practice, large age-gaps may result in negative outcomes for younger women married to older men—e.g., because of power differences in these relationships. Testing for the existence of sexual conflict over the size of the spousal age-gap in Tanzania, researchers found no evidence that large age-gaps are harmful to women. Here, we conceptually replicate this previous work, and assess the relationship between spousal age-gaps, partner preferences, and individual well-being in four communities in Colombia. We extend prior methods by inferring the size of idealized age-gaps using network structured mate-choice games, and measuring the realized age-gap directly among ever-married partners. Our analyses suggest that there is limited evidence of sexual conflict over the size of the spousal age-gap in these communities. First, realized age-gaps are not large on average—around 1–7 years across communities. Second, the age-gaps that do exist are consistent with the preferences of both men and women—at least during their early to middle reproductive periods. And, lastly, large age-gaps are not negatively associated with measures of fertility or well-being for either sex. Our results underscore the importance of appreciating the cultural context within which behavioral practices with potentially negative consequences are situated.  相似文献   

19.
Host populations for the plague bacterium, Yersinia pestis, are highly variable in their response to plague ranging from near deterministic extinction (i.e., epizootic dynamics) to a low probability of extinction despite persistent infection (i.e., enzootic dynamics). Much of the work to understand this variability has focused on specific host characteristics, such as population size and resistance, and their role in determining plague dynamics. Here, however, we advance the idea that the relative importance of alternative transmission routes may vary causing shifts from epizootic to enzootic dynamics. We present a model that incorporates host and flea ecology with multiple transmission hypotheses to study how transmission shifts determine population responses to plague. Our results suggest enzootic persistence relies on infection of an off-host flea reservoir and epizootics rely on transiently maintained flea infection loads through repeated infectious feeds by fleas. In either case, early-phase transmission by fleas (i.e., transmission immediately following an infected blood meal) has been observed in laboratory studies, and we show that it is capable of driving plague dynamics at the population level. Sensitivity analysis of model parameters revealed that host characteristics (e.g., population size and resistance) vary in importance depending on transmission dynamics, suggesting that host ecology may scale differently through different transmission routes enabling prediction of population responses in a more robust way than using either host characteristics or transmission shifts alone.  相似文献   

20.
How do we see Southeast Asian and diasporic visual culture today? This is the central question we ask in the Introduction to this special issue of Visual Anthropology. To answer the question, we trouble the geographic designation of “Southeast Asia” and how the region’s arts and culture have traveled and are received at the present moment. We posit that we need to see Southeast Asia and its diasporas differently. Most notably, we argue that through the lens of gender and sexuality we can better visualize and analyze the critical and creative strategies of artists and writers situated in many parts of the world. We foreground the collected essays, art pieces and poetry that query what it means to labor for the state, the art world or the academy. And as we emphasize, the collection brings together—in color, in varying compositions, in long and short form—the dynamism of art and media texts in all of their complex circulations.  相似文献   

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