首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
This research is based on the discovery of a large number of charcoal kiln sites and abandoned iron mines in Vallferrera (Axial Pyrenees, northeastern Spain). The study reveals that this region has been affected by the metal mining and smelting industry for at least 2,000 years, with maximum intensity in the eighteenth and nineteenth centuries, followed by abandonment of the activity. The region’s woodland dendrochronology and historical records indicate that exploitation of wood charcoal for metalworking affected the past vegetation in the area and impeded the development of mature woodland. Our findings suggest that the greatest changes in vegetation and landscape history occurred at times of particular specialization in socioeconomic activities.
Albert PèlachsEmail:
  相似文献   

2.
Jablonka and Lamb's claim that evolutionary biology is undergoing a ‘revolution’ is queried. But the very concept of revolutionary change has uncertain application to a field organized in the manner of contemporary biology. The explanatory primacy of sequence properties is also discussed.
Peter Godfrey-SmithEmail:
  相似文献   

3.
This study focuses on community-based knowledge to analyze the impacts of range enclosures, crop farming, fire suppression and bush encroachment on the communal rangelands of Borana, southern Ethiopia. The knowledge of local herders is the basis for decision making in the utilization and management of grazing lands. We used Borana oral history associated with the period of the gada system to reconstruct environmental change that spans a period of 48 years. Our results show that the use of communities’ perceptions as a basis for evaluating the impacts of land use change on the environment makes an important methodological contribution. Communities’ responses to changing land use resulted in the development of range enclosures, the expansion of crop farming and the fragmentation of the communal rangelands, while the suppression of fire contributed to the expansion of bush encroachment. The overall impact was forage scarcity and greater vulnerability of stock during drought years. We conclude that policymakers could use communities’ knowledge of environmental change to improve the use of the rangelands. We propose that sustainable use of the southern rangelands in the future will require a greater focus on regulating the expansion of enclosures, crop farming and ranching, as well as reintroducing fire where necessary, to control the expansion of bush cover.
Gufu ObaEmail:
  相似文献   

4.
Debates over adaptationism can be clarified and partially resolved by careful consideration of the ‘grain’ at which evolutionary processes are described. The framework of ‘adaptive landscapes’ can be used to illustrate and facilitate this investigation. We argue that natural selection may have special status at an intermediate grain of analysis of evolutionary processes. The cases of sickle-cell disease and genomic imprinting are used as case studies.
Peter Godfrey-SmithEmail:
  相似文献   

5.
Although there is a clear statistical association between expressed emotion (EE) and schizophrenic relapse, our understanding of the mechanisms underlying this relationship is underdeveloped. This study tested a theoretical model in which caregivers’ perceptions of their ill relative’s agency underlie the EE-relapse association. To evaluate this model, we completed qualitative and quantitative analyses of narratives provided by individuals caring for a relative with schizophrenia. The results indicate that high-EE caregivers perceive the expression of symptoms as stemming from their ill relative’s agency more frequently than low-EE caregivers. This was true for both high-EE-criticism and high-EE-emotional overinvolvement caregivers. High-EE and low-EE caregivers did not differ in their perceptions of the role of their ill relative’s agency with regard to the control of symptoms. The findings suggest that EE may be a proxy risk factor for caregivers’ perceptions of their ill relative’s agency.
Nicholas J. K. BreitbordeEmail:
  相似文献   

6.
This paper is an interpretation and defense of Richard Levins’ “The Strategy of Model Building in Population Biology,” which has been extremely influential among biologists since its publication 40 years ago. In this article, Levins confronted some of the deepest philosophical issues surrounding modeling and theory construction. By way of interpretation, I discuss each of Levins’ major philosophical themes: the problem of complexity, the brute-force approach, the existence and consequence of tradeoffs, and robustness analysis. I argue that Levins’ article is concerned, at its core, with justifying the use of multiple, idealized models in population biology.
Michael WeisbergEmail:
  相似文献   

7.
A coalition of environmental activists and professionals created the San Diego Fire Recovery Network (SDFRN) while the largest wildfire in California history was still burning at the city’s edge in October 2003. Acting quickly while the citizenry questioned governmental ability to protect their rapidly growing region, SDFRN proposed to reduce fire risk in a way that altered residential knowledge practices and identity while reshaping governance relationships. While this effort stalled after governmental agencies restored public confidence through massive fire prevention initiatives, SDFRN’s efforts may not have been in vain. Retained within collective memory, SDFRN contributed to community resilience by diversifying possible responses to environmental change and uncertainty. In this way, flexible, informal learning organizations such as SDFRN may serve as “skunkworks,” seizing on disaster in order to incubate social–ecological relationships that might avert greater tragedies to come.
Bruce Evan GoldsteinEmail:
  相似文献   

8.
In 1998, a decree issued by the Indonesian government enabled communities in Krui, Indonesia, to register for concession rights over the area of state forest land planted with their agroforests. Registration would provide farmers with the legal right to manage and benefit from these agroforests. In 2005, we found that even though none of the Krui communities has ever formally applied for their concession rights, the decree has been instrumental in stopping outsiders’ attempts to appropriate these agroforests. Farmers within the state forest zone felt secure enough to continue investing in their complex agroforestry systems, while planting trees reinforced their feeling of security. We conclude that it is not the legal status of tenure, but the perception of tenure security that is of significance in people’s land-use decisions. These results are considered in the wider context of state–community conflicts over forest land in the tropics.
Koen KustersEmail:
  相似文献   

9.
In researching the biomedically-engineered drug Neulasta (filgrastim), a breast cancer patient becomes aware of the extent to which knowledge about the development and marketing of drugs influences her decisions with regard to treatment. Time spent on understanding the commercial interests of insurers and pharmaceutical companies initially thwarts but ultimately aids the healing process. This first-person narrative calls for physicians to recognize that the alignment of commercial interests transgresses the patient’s humanity.
Jane E. SchultzEmail:
  相似文献   

10.
This article contributes to the encouraging recent trend toward more critical examination of the linkages between remote sensing and social analysis of environmental change. Using two case studies from Malawi, we explain the importance of thinking about temporal scale when using remote sensing data. Specifically, from our on-the-ground research, we came to appreciate three important issues: (1) multiple causation and multiple temporal scales operating simultaneously—making inference of casual relations between particular social factors and observed land use changes difficult; (2) ‘visible’ vs. ‘invisible’ processes and events; and (3) ‘continuous’ vs. ‘punctuated’ social and environmental processes. We observe that in each case, social differentiation is key to understanding which temporal frames are most relevant in understanding observed land use dynamics. We conclude that, while these are not entirely new observations, research on the applications of remote sensing in social analysis of environmental change could be enriched by more rigorous examination of linkages between environmental change, temporal scale, and the social relations (including social differentiation) that can help to explain how and why particular temporal frames are most salient.
Pauline E. PetersEmail:
  相似文献   

11.
On the island of Hainan, China, the provincial government has recently committed itself to sustainable development, which requires the integration of social, environmental, and economic factors in decision making. However, while Hainan’s recent Eco-province designation establishes environmental and economic factors as the basis of policy development, it overlooks the equally important social component of sustainability, in which social needs and values are key considerations. This paper presents the results of a study on Hainan in 2002, with government officials, forestry workers, and the Li, an indigenous minority group, and places the province’s situation within the context of both the larger changes underway in China, and the theory and practice of sustainable forestry. The research results show that the government of Hainan has not yet been able to manage both social welfare and environmental and economic issues, demonstrating the difficulty of implementing sustainable forestry and of balancing short- with long-term goals. The inclusion of Li communities in forestry-related decision making could reduce tensions between local communities and forestry management and also improve the sustainability of the government’s forestry practices.
Susan K. WismerEmail:
  相似文献   

12.
Does Investment in the Sexes Differ When Fathers Are Absent?   总被引:1,自引:1,他引:0  
This study examines child survival and growth in a patrilineal Ethiopian community as a function of father absence and sex. In line with evolutionary predictions for sex-biased parental investment, the absence of a father and associated constraints on household resources is more detrimental for sons’ than daughters’ survival in infancy. Father absence doubles a son’s risk of dying in infancy but has a positive influence on the well-being of female members of the household, improving daughter survival, growth, and maternal nutritional status. Lack of paternal investment may be compensated for by other matrilateral kin through increased reciprocity between mother, daughter, and sister.
Mhairi A. GibsonEmail:
  相似文献   

13.
Sub-Antarctic Marion Island has had a permanent research station for 50 years and the islands Wandering Albatrosses have been intensively studied for 20 years. The reactions of breeding birds to approaches by a human on foot were recorded. Three response variables were calculated: intensity of vocal reaction (IVR), intensity of non-vocal reaction (INR) and overall response index (ORI). At 5 m from the nest, twice as many birds stood and/or vocalised as at 15 m. Nearest neighbour distance, age and gender did not explain individual variability of responses. Study colony birds had higher IVR scores than non-study colony birds; birds at colonies closest to the station had the highest ORI scores. A better breeding record was associated with lower IVR and ORI scores, but a causative relationship remains to be demonstrated. A minimum viewing distance of 25 m is recommended for breeding Wandering Albatrosses.
Marienne S. de VilliersEmail: Fax: +27-21-6503434
John CooperEmail:
Peter G. RyanEmail:
  相似文献   

14.
This paper demonstrates that the human visual system, the primary sensory conduit for primates, processes ambient energy in a way that obligatorily constructs the objects that we ineluctably perceive. And since our perceptual apparatus processes information only in terms of objects (along with the properties and movements of objects), we are limited in our ability to comprehend ‘what is’ when we move beyond our ordinary world of midsize objects—as, for example, when we address the micro microworld of quantum physics.
Philip Richard SullivanEmail:
  相似文献   

15.
Event-related brain potentials (ERP) are important neural correlates of cognitive processes. In the domain of language processing, the N400 and P600 reflect lexical-semantic integration and syntactic processing problems, respectively. We suggest an interpretation of these markers in terms of dynamical system theory and present two nonlinear dynamical models for syntactic computations where different processing strategies correspond to functionally different regions in the system’s phase space.
Peter beim GrabenEmail:
  相似文献   

16.
We construct a mapping from complex recursive linguistic data structures to spherical wave functions using Smolensky’s filler/role bindings and tensor product representations. Syntactic language processing is then described by the transient evolution of these spherical patterns whose amplitudes are governed by nonlinear order parameter equations. Implications of the model in terms of brain wave dynamics are indicated. Electronic supplementary material  The online version of this article (doi: ) contains supplementary material, which is available to authorized users.
Peter beim GrabenEmail:
  相似文献   

17.
Though the formal coherence and empirical utility of Marcello Barbieri’s concept of organic code have been starting to become established, a general conception of how the semantics of organic codes is related to the pragmatics of their use is still missing. Barbieri took a first step towards such a conception by distinguishing three types of semiosis in living systems: manufacturing, signalling, and interpretive semiosis. This paper integrates Barbieri’s distinction into Roman Jakobson’s systematization of possible functions of messages in order to propose a general conception of possible types of semiosis in living systems. As a result, Barbieri’s thesis that manufacturing and signalling semiosis are basic types of semiosis, can be confirmed and completed communication-theoretically.
Stefan ArtmannEmail:
  相似文献   

18.
19.
Studies on the effects of a variety of exogenous and anthropogenic environmental factors, including endocrine disruptors, heavy metals, UV light, high temperature, and others, on marine organisms have been presented at the 2nd Bilateral Seminar Italy–Japan held in November 2006. Reports were discussed in order to reveal the current situation of marine ecosystems, aiming at evaluation and prediction of environmental risks.
V. MatrangaEmail:
  相似文献   

20.
This paper discusses the persistent devaluation of the girl child in India and the link between the entrenched perception of female valuelessness and the actual practice of infanticide of girl babies or foetuses. It seeks to place female infanticide, or ‘gendercide,’ within the context of Western-derived conceptions of ethics, justice and rights. To date, current ethical theories and internationally purveyed moral frameworks, as well as legal and political declarations, have fallen short of an adequate moral appraisal of infanticide. This paper seeks to rethink the issue.
Renuka M. SharmaEmail:
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

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