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1.
The study of global environmental change and its effect on biodiversity and ecosystem function is at an exciting crossroads, at which ideas developed largely through theory and small-scale experiments are now being tested with ecosystem services as they are delivered to people in real-world landscapes. Pollinators and pollination are emerging as a model system for exploring these questions, which inherently required working large spatio-temporal scales. In this Invited View, I discuss current questions that are at the leading edge of this research. I first point out some surprising knowledge gaps in our understanding of pollinators’ response to global change. I then outline several ways in which current understanding of the biodiversity-ecosystem functioning relationship might be transformed by studies conducted at large spatio-temporal scales. Specifically, I propose two hypotheses that relate to the number of species required to saturate ecosystem function, and to the mechanisms through which biodiversity stabilizes ecosystem function over space or time.  相似文献   

2.
Attention-deficit/hyperactivity disorder (ADHD) has been shown to continue into old age. Studies in children and younger adults show a reduction in hyperactive-impulsive symptoms, whereas the number of inattentive symptoms stays stable. The current study examined the lifetime stability of ADHD symptoms up to old age. Data on ADHD diagnosis and symptoms were collected in a two-phase side-study (N = 231) of the Longitudinal Aging Study Amsterdam. Paired t tests and ANCOVAs were used to analyze the data. Paired t test suggests continuity of the number of reported ADHD symptoms currently present and present in childhood. The change in the balance of inattentive/hyperactive-impulsive symptoms at present and in childhood is also the same in persons with ADHD. Finally, the difference in the change in the balance of inattentive/hyperactive-impulsive symptoms in those with and without ADHD suggests continuity throughout the life span. Our results suggest that diagnostic criteria developed for younger adults may be used among older adults. However, we collected our data retrospectively, which may have biased our results. Future research should follow larger cohorts of patients with ADHD prospectively over the life span.  相似文献   

3.
In this article, I question regional context as primary context in anthropological analyses. I argue that the idea of historical continuity in a geographical locality/region might prevent us from understanding not only radical change, but also more gradually emerging social patterns that connect the ethnography to very different kinds of histories and places. Concretely, I focus on the global Charismatic and Pentecostal movements, and as an experiment, I ask whether it is possible to go to ‘Pentecost’, instead of going to Melanesia. With ‘going to Pentecost’ as a heuristic device, I suggest it is possible to overcome methodological challenges in the study of global religious movements. In this article, I thus trace the practices and articulations of my interlocutors as part of a wider Pentecostal universe. I show how notions of seeing, borders, separations, and protection are crucial in ‘Pentecost’, and I connect this to key Christian ideas and values.  相似文献   

4.
It is generally believed that peasant culture is incompatible with industrial civilization. Furthermore, peasant-city relationships are often dichotomized, suggesting maximal cultural distance. In view of data gathered in a peasant village of the Lower Rhineland it is argued here that over a period of seventy years at least the villagers were able not only to survive within an industrial civilization without losing their cultural identity but also to we industrial wage-earning as a means of preserving the essentials of their peasant way of life. Their ability to adapt to technological change is related here to a long history of previous adaptations beginning in the Middle Ages and leading to the Second Agricultural Revolution. Historical comparison between the city and the village suggests cultural continuity of urban lower class and peasantry rather than cultural polarity between the two segments. [Europe, culture and society; culture change; peasant culture]  相似文献   

5.
Kaye J 《Human genetics》2011,130(3):377-382
The future holds the possibility to link and network biobanks, existing biorepositories and reference databases for research purposes in ways that have not been possible before. There is the potential to develop 'research portals' that will enable researchers to access these research resources that are located around the globe with the click of a mouse. In this paper, I will argue that our current governance system for research is unable to provide all of the oversight and accountability mechanisms that are required for this new way of doing research that is based upon flows of data across international borders. For example, our current governance framework for research is nationally based, with a complex system of laws, policies and practice that can be unique to a jurisdiction. It is also evident that many of the nationally based governance bodies in this field do not have the legal powers or expertise to adjudicate on the complex issues, such as privacy and disclosure risks that are raised by cross-border data sharing. In addition, the conceptual underpinning of this research governance structure is based on the "one researcher, one project, one jurisdiction" model. In the conclusion of this paper, I lay out some preliminary ideas as to how this system has to change to accommodate research that is based on networks. I suggest that a move to digital governance mechanisms might be a start to making research governance systems more appropriate for the 21st century.  相似文献   

6.
Sex differences are recognized in children's free drawings with respect to motifs, colors, figure compositions, and expression. Boys tend to draw mobile objects and mechanical objects with dark or cold colors and often use bird's-eye-view composition when they draw pictures, whereas girls like to draw human motifs (especially girls and women), flowers, and butterflies with light and warm colors and tend to arrange motifs in a row on the ground. Analyses were made on the drawings of girls with congenital adrenal hyperplasia (CAH) and unaffected boys and girls, using masculine and feminine indexes. Sex difference in masculine and feminine indexes was clear in the drawings by unaffected boys and girls. Their drawings do not or mostly do not contain characteristics typical of the opposite sex. Compared with those of unaffected girls, the pictures of CAH girls more strongly showed masculine characteristics. The feminine index for the pictures of CAH girls was significantly lower than that for unaffected girls, while the masculine index for CAH girls was significantly higher than that for unaffected girls. Furthermore, the masculine index for CAH girls was not significantly different from that of unaffected boys. These results suggest that androgen exposure during fetal life may contribute to shaping masculine characteristics in children's free drawings.  相似文献   

7.
Regular unscheduled movements of rancherías within a confined area or settlement district result in the phenomenon described as "village drift," a process whereby a settlement may change its location gradually by several kilometers over a period of years. This article presents a model of village drift based on data acquired from recent archaeological and geomorphological field studies and archival research on the Akimel O'odham, the Gila River Pima of south-central Arizona. The model provides an excellent example of human ecodynamics---an emerging landscape perspective that emphasizes the coevolution of humans and their ecosystem---with implications for understanding prehistoric and historic settlement in desert riverine environments.  相似文献   

8.
《Acta Oecologica》2006,29(1):72-77
Extrapolating the results from experiments on effects of species loss to natural systems is difficult since most studies, with the exception of microbial microcosm studies, have been performed on relatively short time-scales. One problem with short-term, experimental studies is that complex interactions between species in natural systems may alter the importance of underlying mechanisms over time thus making the effects observed in the experiments representative of a transient phase. Although some evidence indicates that initial effects of species richness observed in short-term experiments may be persistent, other results suggest that effects may change over time. Using detritivorous insect larvae in freshwater mesocosms, where both facilitation and niche differentiation mechanisms were operating and where resources were gradually decreasing, I examined the effects of species richness over time. I found that the initial effect of species richness on ecosystem function was enhanced over time when systems of high and low diversity were compared. There was an overall effect of species composition on larval growth, and when analysing the growth of each species separately it was found that one species was significantly affected by species richness, one showed a marginally insignificant effect of species richness, and the third species was significantly, differently affected by species richness over time. Thus, the results show that species loss initially leading to small, negative, or even undetectable, effects on ecosystem function may increase in importance over the long-term.  相似文献   

9.
Despite the recent attention given to the archaeology of childhood, households continue to be treated by archaeologists as the product of adult behavior and activities. Yet children shaped the decisions and motivations of adults and influenced the structure and organization of daily activities and household space. Further, children's material culture serves to both create and disrupt social norms and daily life, making children essential to understanding broader mechanisms of change and continuity. Thus, archaeologists should reconceptualize houses as places of children. This research brings together multiple lines of evidence from the Early Postclassic site of Xaltocan, Mexico, including ethnohistory, burials, and figurines to reconstruct the social roles and identities of children and to problematize our understanding of households. I argue that thinking of houses as places of children enables us to see that children were essential to daily practice, the construction and transmission of social identity, and household economic success.  相似文献   

10.
The well-known argument against the Search for ExtraTerrestrial Intelligence (SETI) due to George Gaylord Simpson is re-analyzed almost half a century later, in the light of our improved understanding of preconditions for the emergence of life and intelligence brought about by the ongoing “astrobiological revolution”. Simpson’s argument has been enormously influential, in particular in biological circles, and it arguably fueled the most serious opposition to SETI programmes and their funding. I argue that both proponents and opponents of Simpson’s argument have occasionally mispresented its core content. Proponents often oversimplify it as just another consequence of biological contingency, thus leaving their position open to general arguments limiting the scope of contingency in evolution (such as the recent argument of Geerat Vermeij based on selection effects in the fossil record). They also tend to neglect that the argument has been presented as essentially atemporal, while referring to entities and processes that are likely to change over time; this has become even less justifiable as our astrobiological knowledge increased in recent years. Opponents have failed to see that the weaknesses in Simpson’s position could be removed by restructuring of the argument; I suggest one way of such restructuring, envisioned long ago in the fictional context by Stanislaw Lem. While no firm consensus has emerged on the validity of Simpson’s argument so far, I suggest that, contrary to the original motivation, today it is less an anti-SETI argument, and more an astrobiological research programme. In this research programme, SETI could be generalized into a platform for testing some of the deepest assumptions about evolutionary continuity and the relative role of contingency versus convergence on unprecedented spatial and temporal scales.  相似文献   

11.
Sigrid D. P. Smith 《Oikos》2012,121(5):675-686
Ecological communities can vary greatly in species composition. Often this variation is discontinuous, in that abrupt changes in composition occur over small distances in space or short periods of time. A wide range of hypotheses from different subfields of ecology have been proposed to explain these patterns. I suggest a framework to quantitatively evaluate these hypotheses with observational data by characterizing 1) how community composition varies across sites in space, 2) how community composition varies through time, and 3) the possible drivers of this variation. I applied this approach to understand the community composition of producers in temporary and semipermanent wetlands in Michigan, USA. I identified several distinct community states which were variously dominated by particular plant functional groups (submerged, floating or emergent plants) or had no plants throughout a season. Evaluating possible hypotheses to explain this variation, I found that similar communities were not necessarily clustered near each other, suggesting that dispersal was not limited for these plants. Some sites exhibited a great deal of change in plant composition among years, shifting between two community states, but there was relatively little change at sites within a year. Moreover, these shifts did not occur in a particular order to suggest directional change or repeating cycles. Community composition was associated with several environmental variables such as pH, light and depth, and multivariate analyses suggested that species had complex, nonlinear responses to these possible drivers. Alternative stable states and interactions among multiple nonlinear drivers best explained the patterns observed in these wetlands. By formalizing initial data collection in other systems with the framework suggested here, we may gain insight into the causes of alternative community states beyond wetlands and the role of climate change and other anthropogenic forces in precipitating transitions between states.  相似文献   

12.
Here we present an analytical technique for the measurement and evaluation of changes in chronologically sequenced assemblages. To illustrate the method, we studied the cultural evolution of European cooking as revealed in seven cook books dispersed over the past 800 years. We investigated if changes in the set of commonly used ingredients were mainly gradual or subject to fashion fluctuations. Applying our method to the data from the cook books revealed that overall, there is a clear continuity in cooking over the ages – cooking is knowledge that is passed down through generations, not something (re-)invented by each generation on its own. Looking at three main categories of ingredients separately (spices, animal products and vegetables), however, disclosed that all ingredients do not change according to the same pattern. While choice of animal products was very conservative, changing completely sequentially, changes in the choices of spices, but also of vegetables, were more unbounded. We hypothesize that this may be due a combination of fashion fluctuations and changes in availability due to contact with the Americas during our study time period. The presented method is also usable on other assemblage type data, and can thus be of utility for analyzing sequential archaeological data from the same area or other similarly organized material.  相似文献   

13.
Old ideas often persist long after sound evidence dictates otherwise. I attempt to report one such case in the life sciences, by pointing out what are perceived to be fundamental flaws or questions in conventional wisdom. It is my experience that much evidence not in support of the well accepted membrane pump view of the living cell has been overlooked, forgotten or even ignored. In presenting this idea, the evolution of our knowledge from the establishment of cellular and protoplasmic theory to the emergence of solution theory is presented. The universal hypothesis based on physical chemical principles is presented, followed by the advent of the membrane-situated energy-requiring pump. The experimental demonstration of an inadequate energy supply for the first pump is discussed, followed by a review of new evidence that calls to question the use of dilute solution theory in describing adequately cellular function. Finally, roles for cellular water are suggested to explain the cellular exclusion of sodium and to serve as a barometer for the healthy state. Within the context of a metaphor, I attempt to qualitatively embrace the physical findings. It is concluded that the mobility of water molecules may be considered to change with the progression of normal tissue to a state of disease. These changes in the mobility of water molecules are "fingerprinted" by changes in the molecular motion of the solids.  相似文献   

14.
1. Climate change is expected to produce shifts in species distributions as well as behavioural, life-history, and/or morphological adaptations to find suitable conditions or cope with the altered environment. Most of our knowledge on this issue comes from studies on vertebrates, mainly endotherm species. However, it remains uncertain how small ectotherms, such as insects, respond to increased temperature. 2. This study tested whether climate change over the last 100 years (1904–2013) has affected morphological and functional traits in workers of the social wasp Dolichovespula sylvestris in the Iberian Peninsula. 3. Head width and forewing length, as well as body mass and wing area (assuming no change in shape), decreased over time and with increased mean annual temperature, even when controlling for geographical location and altitude. Interestingly, wing size decreased with a steeper slope compared with body size. If there is no change in wing shape, this would lead to an invariable wing loading (body mass:wing area ratio) over time, with potential consequences on flying ability of more recent (and thus smaller) wasp individuals. 4. These results suggest that recent climate change is leaving morphological signatures in social wasps, increasing the evidence for this phenomenon in insects. The data furthermore suggest that the known efficient thermoregulatory ability of social insect colonies may not successfully buffer the effect of global warming.  相似文献   

15.
The claim that conceptual systems change is a platitude. That our conceptual systems are theory-laden is no less platitudinous. Given evolutionary theory, biologists are led to divide up the living world into genes, organisms, species, etc. in a particular way. No theory-neutral individuation of individuals or partitioning of these individuals into natural kinds is possible. Parallel observations should hold for philosophical theories about scientific theories. In this paper I summarize a theory of scientific change which I set out in considerable detail in a book that I shall publish in the near future. Just as few scientists were willing to entertain the view that species evolve in the absence of a mechanism capable of explaining this change, so philosophers should be just as reticent about accepting a parallel view of conceptual systems in science evolving in the absence of a mechanism to explain this evolution. In this paper I set out such a mechanism. One reason that this task has seemed so formidable in the past is that we have all construed conceptual systems inappropriately. If we are to understand the evolution of conceptual systems in science, we must interpret them as forming lineages related by descent. In my theory, the notion of a family resemblance is taken literally, not metaphorically. In my book, I set out data to show that the mechanism which I propose is actually operative. In this paper, such data is assumed.I wish to thank both Michael Ruse and Ronald Giere for suggesting improvements in an early draft of this paper. This paper is an abstract of a very long book. The number of people who helped me in developing the ideas set out in this book is extremely large, so large that I decided to defer expressing my gratitude to them until its appearance.  相似文献   

16.
We propose an online binary classification procedure for cases when there is uncertainty about the model to use and parameters within a model change over time. We account for model uncertainty through dynamic model averaging, a dynamic extension of Bayesian model averaging in which posterior model probabilities may also change with time. We apply a state-space model to the parameters of each model and we allow the data-generating model to change over time according to a Markov chain. Calibrating a "forgetting" factor accommodates different levels of change in the data-generating mechanism. We propose an algorithm that adjusts the level of forgetting in an online fashion using the posterior predictive distribution, and so accommodates various levels of change at different times. We apply our method to data from children with appendicitis who receive either a traditional (open) appendectomy or a laparoscopic procedure. Factors associated with which children receive a particular type of procedure changed substantially over the 7 years of data collection, a feature that is not captured using standard regression modeling. Because our procedure can be implemented completely online, future data collection for similar studies would require storing sensitive patient information only temporarily, reducing the risk of a breach of confidentiality.  相似文献   

17.
In this essay, I suggest that American sociocultural anthropology has been a "color blind" profession for nearly a half century and that, as a discipline, we need to restore and refine our color perceptions in order to fight the supposedly fixed opposition in American society between "black" and "white" and deal with the racist consequences of this folk opposition. In the first section, 'How Anthropology Became 'Color Blind,'" I delineate the circumstances under which anthropology became the "color blind" profession. In the second section, "Teaching Color Blindness," I discuss the tendency, in teaching sociocultural anthropology, to ignore racism and its effects. In the final section, "Restoring Color Vision," I take up the questions of what the profession needs to do next to cope with racism and its consequences, emphasizing especially the issue of group identities, how they are formulated, inculcated, and overcome, and proposing a Foucauldian model—following Foucault's lead in analyzing relations of biopower and race—for formulating new ways of responding to and resisting the inevitable recastings of racist ideas,  相似文献   

18.
Testing a covariotide model of DNA substitution   总被引:10,自引:0,他引:10  
The concomitantly variable codons hypothesis of DNA substitution argues that at any time only a fraction of the codons in a gene are capable of accepting a mutation. However, as mutations are fixed at some positions in a gene, the sites that are potentially variable also change because of changed functional constraints. This hypothesis has been termed the "covarion" hypothesis or when the model is applied to nucleotides, the "covariotide" hypothesis. The covarion-covariotide model has proven to be remarkably difficult to test. Here I examine a covariotide hypothesis for 11 genes using a likelihood ratio test. I show that in nine of the genes examined a covariotide model provides a better explanation of the data than a model that does not allow constraints to change over time.  相似文献   

19.
Five rural villages in Qianjiang County (Hubei province), PR China, were investigated to collect information on the socioeconomic characteristics relevant to farming system analysis. In each village, 50 households were randomly sampled and household heads interviewed. We first present the results of this conventional survey, which describes these five villages in terms of conventional socioeconomic parameters such as demographic variables, land availability and profiles of land use, time allocation and profiles of working time use, cash flows, and degree of food self-sufficiency. Then we change focus by characterizing household types rather than village types. This is done analyzing the same raw data aggregated at the household level to illustrate the difference of a parallel readings at different hierarchical levels. Finally, we present a new approach to organize the information gathered in the conventional way into “typologies” referring to both household and village level. Such a passage makes possible a multidimensional reading of the system. One key concept of this analysis is the land-time budget (LTB) approach, which is first explained in theoretical terms and then illustrated with examples applied to our data set.  相似文献   

20.
The study of biodiversity has grown exponentially in the last thirty years in response to demands for greater understanding of the function and importance of Earth's biodiversity and finding solutions to conserve it. Here, we test the hypothesis that biodiversity science has become more interdisciplinary over time. To do so, we analyze 97,945 peer‐reviewed articles over a twenty‐two‐year time period (1990–2012) with a continuous time dynamic model, which classifies articles into concepts (i.e., topics and ideas) based on word co‐occurrences. Using the model output, we then quantify different aspects of interdisciplinarity: concept diversity, that is, the diversity of topics and ideas across subdisciplines in biodiversity science, subdiscipline diversity, that is, the diversity of subdisciplines across concepts, and network structure, which captures interactions between concepts and subdisciplines. We found that, on average, concept and subdiscipline diversity in biodiversity science were either stable or declining, patterns which were driven by the persistence of rare concepts and subdisciplines and a decline in the diversity of common concepts and subdisciplines, respectively. Moreover, our results provide evidence that conceptual homogenization, that is, decreases in temporal β concept diversity, underlies the observed trends in interdisciplinarity. Together, our results reveal that biodiversity science is undergoing a dynamic phase as a scientific discipline that is consolidating around a core set of concepts. Our results suggest that progress toward addressing the biodiversity crisis via greater interdisciplinarity during the study period may have been slowed by extrinsic factors, such as the failure to invest in research spanning across concepts and disciplines. However, recent initiatives such as the Intergovernmental Science‐Policy Platform on Biodiversity and Ecosystem Services (IPBES) may attract broader support for biodiversity‐related issues and hence interdisciplinary approaches to address scientific, political, and societal challenges in the coming years.  相似文献   

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