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1.
A comprehensive assessment of the impacts of climate change on agro-ecosystems over this century is developed, up to 2080 and at a global level, albeit with significant regional detail. To this end an integrated ecological-economic modelling framework is employed, encompassing climate scenarios, agro-ecological zoning information, socio-economic drivers, as well as world food trade dynamics. Specifically, global simulations are performed using the FAO/IIASA agro-ecological zone model, in conjunction with IIASAs global food system model, using climate variables from five different general circulation models, under four different socio-economic scenarios from the intergovernmental panel on climate change. First, impacts of different scenarios of climate change on bio-physical soil and crop growth determinants of yield are evaluated on a 5' X 5' latitude/longitude global grid; second, the extent of potential agricultural land and related potential crop production is computed. The detailed bio-physical results are then fed into an economic analysis, to assess how climate impacts may interact with alternative development pathways, and key trends expected over this century for food demand and production, and trade, as well as key composite indices such as risk of hunger and malnutrition, are computed. This modelling approach connects the relevant bio-physical and socio-economic variables within a unified and coherent framework to produce a global assessment of food production and security under climate change. The results from the study suggest that critical impact asymmetries due to both climate and socio-economic structures may deepen current production and consumption gaps between developed and developing world; it is suggested that adaptation of agricultural techniques will be central to limit potential damages under climate change.  相似文献   

2.
This paper provides an overview of the development of Americanist archeology in the United States.
Since the 1920s, there have been two, and sometimes more, interpretive communities among Americanist archeologists in the United States.
These reflect and are related to the development of U.S. society. One articulates the concerns of national capital and its allies; the other, the interests of
international capital and its allies. They are grounded in different theoretical traditions. The discourses produced by their proponents resonate with
particular world views that reflect different relations to power.  相似文献   

3.
成功  张家楠  薛达元 《生态学报》2014,34(16):4785-4793
传统生态知识是民族生态学研究的核心范畴,国外已有多年的研究基础,国内的相关研究正是方兴未艾。通过文献查询和比较分析等方法,介绍了国外已有的传统生态知识的民族生态学分析框架的3个模型:知识-实践-信仰的三角形框架;本土经验知识-资源管理知识-社会制度知识-世界观知识的四椭圆框架;事实观察-管理体系-旧有及当下利用-伦理价值-文化特征-宇宙观的五边形框架。结合田野调查研究,提出了一个立体的传统生态知识的民族生态学分析模型,强调了传统生态知识的动态特征,将民族对于自然的被动认识和主动认知、民族人际关系规范、民族的哲学与伦理等方面所呈现出的传统生态知识进行了分类,从而为民族生态学的调查研究提供了方法上的建议。最后总结了这个立体的传统生态知识分析框架的意义,并建议在我国的生态文明建设中发展和应用民族生态学。  相似文献   

4.
Cybernetic modeling strives to uncover the inbuilt regulatory programs of biological systems and leverage them toward computational prediction of metabolic dynamics. Because of its focus on incorporating the global aims of metabolism, cybernetic modeling provides a systems-oriented approach for describing regulatory inputs and inferring the impact of regulation within biochemical networks. Combining cybernetic control laws with concepts from metabolic pathway analysis has culminated in a systematic strategy for constructing cybernetic models, which was previously lacking. The newly devised framework relies upon the simultaneous application of local controls that maximize the net flux through each elementary flux mode and global controls that modulate the activities of these modes to optimize the overall nutritional state of the cell. The modeling concepts are illustrated using a simple linear pathway and a larger network representing anaerobic E. coli central metabolism. The E. coli model successfully describes the metabolic shift that occurs upon deleting the pta-ackA operon that is responsible for fermentative acetate production. The model also furnishes predictions that are consistent with experimental results obtained from additional knockout strains as well as strains expressing heterologous genes. Because of the stabilizing influence of the included control variables, the resulting cybernetic models are more robust and reliable than their predecessors in simulating the network response to imposed genetic and environmental perturbations.  相似文献   

5.
Globality and Constructions of World Health   总被引:1,自引:0,他引:1  
Explorations of the social construction of health and illness reveal that popular and professional discourses on health and disease implicitly contain underlying images of how societies can or should be structured. Globality, which is a notion that refers to the consciousness of the world as a single place, suggests that these images of world structure are now salient. This article describes four current discourses of "world health" and discusses them in terms of their underlying ideal images of world order. The four images of the world are defined in terms of four elemental points of reference: individuals, societies, the system of societies, and humankind. These ideal images have either a gemeinschaft (community) or gesellschaft (society) orientation. An anthropology of globality can refine and extend our understandings of discourses of world health. Sensitivity to these discourses and their world-oriented ideological roots should help to demystify the notion of world health. [world health, globality, global culture]  相似文献   

6.
Tensor subspace transformation, a commonly used subspace transformation technique, has gained more and more popularity over the past few years because many objects in the real world can be naturally represented as multidimensional arrays, i.e. tensors. For example, a RGB facial image can be represented as a three-dimensional array (or 3rd-order tensor). The first two dimensionalities (or modes) represent the facial spatial information and the third dimensionality (or mode) represents the color space information. Each mode of the tensor may express a different semantic meaning. Thus different transformation strategies should be applied to different modes of the tensor according to their semantic meanings to obtain the best performance. To the best of our knowledge, there are no existing tensor subspace transformation algorithm which implements different transformation strategies on different modes of a tensor accordingly. In this paper, we propose a fusion tensor subspace transformation framework, a novel idea where different transformation strategies are implemented on separate modes of a tensor. Under the framework, we propose the Fusion Tensor Color Space (FTCS) model for face recognition.  相似文献   

7.
The ecological impacts of alien species invasion are a major threat to global biodiversity. The increasing number of invasion events by alien species and the high cost and difficulty of eradicating invasive species once established require the development of new methods and tools for predicting the most susceptible areas to invasion. Invasive pollinators pose serious threats to biodiversity and human activity due to their close relationship with many plants (including crop species) and high potential competitiveness for resources with native pollinators. Although at an early stage of expansion, the bumblebee species Bombus terrestris is becoming a representative case of pollinator invasion at a global scale, particularly given its high velocity of invasive spread and the increasing number of reports of its impacts on native bees and crops in many countries. We present here a methodological framework of habitat suitability modeling that integrates new approaches for detecting habitats that are susceptible to Bombus terrestris invasion at a global scale. Our approach did not include reported invaded locations in the modeling procedure; instead, those locations were used exclusively to evaluate the accuracy of the models in predicting suitability over regions already invaded. Moreover, a new and more intuitive approach was developed to select the models and evaluate different algorithms based on their performance and predictive convergence. Finally, we present a comprehensive global map of susceptibility to Bombus terrestris invasion that highlights priority areas for monitoring.  相似文献   

8.
Proteins have a highly dynamic nature and there is a complex interrelation between their structural dynamics and binding behavior. By assuming various conformational ensembles, they perform both local and global fluctuations to interact with other proteins in a dynamic infrastructure adapted to functional motion. Here, we show that there is a significant association between allosteric mutations, which lead to high-binding-affinity changes, and the hinge positions of global modes, as revealed by a large-scale statistical analysis of data in the Structural Kinetic and Energetic Database of Mutant Protein Interactions (SKEMPI). We further examined the mechanism of allosteric dynamics by conducting studies on human growth hormone (hGH) and pyrin domain (PYD), and the results show how mutations at the hinge regions could allosterically affect the binding-site dynamics or induce alternative binding modes by modifying the ensemble of accessible conformations. The long-range dissemination of perturbations in local chemistry or physical interactions through an impact on global dynamics can restore the allosteric dynamics. Our findings suggest a mechanism for the coupling of structural dynamics to the modulation of protein interactions, which remains a critical phenomenon in understanding the effect of mutations that lead to functional changes in proteins.  相似文献   

9.
Herbivory by domestic and wild ungulates is a major driver of global vegetation dynamics. However, grazing is not considered in dynamic global vegetation models, or more generally in studies of the effects of environmental change on ecosystems at regional to global scale. An obstacle to this is a lack of empirical tests of several hypotheses linking plant traits with grazing. We, therefore, set out to test whether some widely recognized trait responses to grazing are consistent at the global level. We conducted a meta‐analysis of plant trait responses to grazing, based on 197 studies from all major regions of the world, and using six major conceptual models of trait response to grazing as a framework. Data were available for seven plant traits: life history, canopy height, habit, architecture, growth form (forb, graminoid, herbaceous legume, woody), palatability, and geographic origin. Covariates were precipitation and evolutionary history of herbivory. Overall, grazing favoured annual over perennial plants, short plants over tall plants, prostrate over erect plants, and stoloniferous and rosette architecture over tussock architecture. There was no consistent effect of grazing on growth form. Some response patterns were modified by particular combinations of precipitation and history of herbivory. Climatic and historical contexts are therefore essential for understanding plant trait responses to grazing. Our study identifies some key traits to be incorporated into plant functional classifications for the explicit consideration of grazing into global vegetation models used in global change research. Importantly, our results suggest that plant functional type classifications and response rules need to be specific to regions with different climate and herbivory history.  相似文献   

10.
Catalytic loop motions facilitate substrate recognition and binding in many enzymes. While these motions appear to be highly flexible, their functional significance suggests that structure-encoded preferences may play a role in selecting particular mechanisms of motions. We performed an extensive study on a set of enzymes to assess whether the collective/global dynamics, as predicted by elastic network models (ENMs), facilitates or even defines the local motions undergone by functional loops. Our dataset includes a total of 117 crystal structures for ten enzymes of different sizes and oligomerization states. Each enzyme contains a specific functional/catalytic loop (10–21 residues long) that closes over the active site during catalysis. Principal component analysis (PCA) of the available crystal structures (including apo and ligand-bound forms) for each enzyme revealed the dominant conformational changes taking place in these loops upon substrate binding. These experimentally observed loop reconfigurations are shown to be predominantly driven by energetically favored modes of motion intrinsically accessible to the enzyme in the absence of its substrate. The analysis suggests that robust global modes cooperatively defined by the overall enzyme architecture also entail local components that assist in suitable opening/closure of the catalytic loop over the active site.  相似文献   

11.
As a result of increased interest in global health, more and more medical students and trainees from the 'developed world' are working and studying in the 'developing world'. However, while opportunities to do this important work increase, there has been insufficient development of ethical guidelines for students. It is often assumed that ethics training in developed world situations is applicable to health experiences globally. However, fundamental differences in both clinical and research settings necessitate an alternative paradigm of analysis. This article is intended for teachers who are responsible for preparing students prior to such experiences. A review of major ethical issues is presented, how they pertain to students, and a framework is outlined to help guide students in their work.  相似文献   

12.
A vision of a world without polio: the OPV cessation strategy.   总被引:1,自引:0,他引:1  
Once the eradication of wild poliovirus has been confirmed, the public health benefits of routine immunization with OPV will no longer outweigh the burden of disease either due to paralysis caused by OPV (vaccine associated paralytic polio), or by outbreaks caused by circulating vaccine-derived polioviruses. The eventual cessation of OPV use in routine immunization programmes worldwide will become necessary to assure a lasting eradication of polio. As the world moves towards polio eradication and its certification, preparations are therefore being intensified for OPV cessation, and the risk management framework for safe OPV cessation is being put in place. The framework includes bio-containment of all known poliovirus and potentially infected substances, development of an international stockpile of oral polio vaccine, ensuring a mechanism for continued global surveillance and response for polio after eradication has been certified, and national policies if countries decide to continue vaccinating with inactivated polio vaccine (IPV). It is ironic that the vaccine on which the world has depended for polio eradication will itself become a risk to eradication once the transmission of wild poliovirus has been interrupted. Final preparations for the eventual global and simultaneous cessation of OPV will require the same level of international cooperation and coordination that has brought the world to the verge of polio eradication.  相似文献   

13.
A duplication growth model of gene expression networks   总被引:8,自引:0,他引:8  
  相似文献   

14.
陆地植被净初级生产力计算模型研究进展   总被引:45,自引:2,他引:45  
植被净初级生产力(NPP)研究是全球变化与陆地生态系统的核心内容之一。在回顾NPP模型研究的基础上,综合分析了气候模型、生态生理过程模型、光能利用率模型各自的优缺点,并对NPP模型研究做出展望。生态生理过程模型是当前陆地NPP估算研究的主要手段,而区域尺度转换则是它所面临的关键问题。近年来光能利用率模型已成为NPP估算的一种全新手段,它利用遥感所获得的全覆盖数据,使区域及全球尺度的NPP估算成为可能,但其生态学机理还有待于进一步研究。已有研究表明,“生态一遥感耦合模型”将是陆地NPP估算的主要发展方向,它融合了生态生理过程模型和光能利用率模型的优点,增强了NPP模型估算的可靠性和可操作性。  相似文献   

15.
It is rare to meet protistologists who are not passionate about their study subject. The vast majority of people, however, never get the chance to hear about the work of these researchers. Although every researcher working on protists is likely to be aware of this situation, efforts made and tools employed for dissemination of knowledge are rarely documented. Following a proposal by the Italian Society of Protistology, a workshop at the 2019 VIII European Congress of Protistology in Rome, Italy, was dedicated to protistological knowledge dissemination. Through the many interventions, we discovered the diversity of efforts to reveal the protistan world to the general public, including museum exhibitions and activities, public understanding of science events, citizen science projects, specific book publications, the use of protists in teaching at all levels from primary school children to university undergraduate students, and to a global audience via social media. The participation of the workshop delegates in the discussions indicated that presentations on the wonderful world of protists to the public not only increase the visibility and accessibility of protistology research but are also very important for the scientific community. Here we report on some of the key aspects of the presentations given in the dissemination workshop.  相似文献   

16.
17.
This paper addresses aspects of 'market culture' as it is expressed in media discourse and among financial traders and corporate managers. Particular focus is placed on their perspectives on risk and responsibility. It is suggested that the ideas and actions of financial traders and corporate leaders contribute in significant ways to the structuring of market transactions across the world. They contribute to the diffusion of perspectives on markets and market actors, influence our understandings of the scope of individual action in market transactions, and play a vital role in the development and organization of contemporary markets. The paper argues that perceptions of risk and responsibility are culturally embedded in the particular contexts in which these actors operate; that they are tightly interwoven as aspects of developing global markets; and presented as forces of nature in discourses that produce not only 'truths' but also power. It is suggested that the fetishization of the market contributes to the evasion of responsibility among financial traders, whereas it presents an opportunity for corporations to position themselves as socially responsible actors. Central to the understanding of the differing conceptualizations of risk and responsibility are perceptions of agency of different actors in financial markets.  相似文献   

18.
In the discussion of globalization and localization, the mainperspectives are either to unveil how global issues are localized, or toanalyze local modifications resulting form global integration. Incontrast, a perspective from the local to the global is proposed to beable to point at local contents of globalization. Such a perspectiverequires an analysis of how locality is constructed locally. In much ofthe current discussion local stands for places, indigenous people,villages, cities, quarters within cities, factories, regions, nations orplaces. Following older research on ethnicity and recent studies ofmigrant cultures, locality is described as a social construction, whichconnects space, local knowledge and social organization. Locality isconnected to support among those belonging to the locality, interestsand the control of resources. Thus competition and potential conflict islinked to locality. Therefore, speaking of locality implies speaking ofpower-differentials. Whether a locality can assume a dominant positionvis-à-vis other localities and define its discourses as dominantor even as universal depends on its organizational and integrativecapacity for the mobilization and application of resources. Thoughcontrol of resources required by others, the respective local knowledgebecomes a necessity for gaining access to these resources. Consequently,global discourses can and often do have a local background. Accordingly,globalization in quite often global dominance from particular localcontext.  相似文献   

19.
Our evolving understanding of ecosystem functioning along with the advent of computational power have paved the way for the development of complex mathematical models that explicitly represent the functional diversity of biotic communities and multiple biogeochemical cycles. The ever-growing demand for more complex models underscores the importance of robust sensitivity analysis (SA) to elucidate the impact of the uncertainty on model inputs and to untangle the parameter covariance patterns that ultimately lead to the emergence of equifinality problems. In this study, we propose a novel multi-pronged SA framework that integrates advanced statistical and machine learning (ML) techniques. Principal component analysis (PCA) is first applied to dissect the wide array of predictive outputs and identify modes of variability in time and/or space. Classification and Regression Tree (CART) analysis is then used to identify a set of splitting decisions connecting threshold values of key state variables and model parameters with different ranges of predictive outputs with management interest. Self-Organizing Maps (SOM) are implemented as a final step to unravel any non-linear associations between model parameters and responses. As a proof-of-concept, we used a complex aquatic biogeochemical model developed for the Bay of Quinte, a eutrophic embayment in Lake Ontario, to examine competition patterns and structural shifts among multiple functional phytoplankton (diatoms, N-fixing cyanobacteria, and Microcystis) and zooplankton (herbivores and omnivores) groups. Our sensitivity analysis framework showed that the parameters representing the dependence of growth and metabolic processes on temperature are particularly influential to recreate plankton community dynamics during the cold period of the year, whereas the interplay among the interspecific resource competition, strength of the prey-predator interactions, and phosphorus availability mainly regulate their dynamics during the growing season. The growth strategies of diatoms, their nutritional quality that determines the assimilation efficiency by zooplankton, along with the ambient nutrient availability determine our capacity to reproduce patterns of cyanobacteria dominance and faithfully depict the severity of harmful algal blooms. Finally, our study discusses the benefits of a broader use of the ML-based SA framework to unravel influential parametric interactions in modulating the behaviors of complex mathematical models.  相似文献   

20.
王耕  常畅  石永辉 《生态学报》2019,39(21):8183-8192
文章以Web of Science数据库中检索的自然资本相关文献为数据源,利用文献计量方法,分析相关文献按年份的数量变化特征、世界各国中主要研究力量和高产作者发文情况,探究目前的研究现状。之后利用Bibexcel得出高频关键词共词矩阵,导入Ucinet和NetDraw得出共现网络可视图,最后对关键词进行聚类分析。研究表明,①自然资本相关文献数量整体呈上升趋势,可大体分为萌芽发展、加速发展和成熟发展3个增长阶段;②从研究力量上看,发达国家的影响力明显强于发展中国家,美国处于遥遥领先的地位,中国起步晚,影响力较小,国际合作需要加强;③根据共词分析得出生态系统服务的价值化和可持续发展是当前的研究热点;④利用聚类分析将高频关键词分成了生态脆弱性与适应性、资本经济与自然资源、生态系统服务和资本经济管理四类。分析结果表明,未来自然资本的研究将集中于生态系统服务的价值化研究、InVEST模型的应用、绿色经济发展与区域绿色经济转型、小尺度区域服务功能价值评估及自然资本的动态评估等方面。  相似文献   

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