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.
2.
We investigate whether accommodating job attributes influence the probability of returning to work three years after a cancer diagnosis. Using a combination of Danish administrative data and a survey carried out among Danish breast, colon, and melanoma skin cancer survivors, we find that the probability of returning to work is significantly and positively correlated with a flexible work schedule during and after cancer treatment. The result is robust when controlling for pre-cancer work experience, job seniority, pre-cancer job dissatisfaction, and post-cancer ability to work. Furthermore, we show that the influence of a flexible schedule varies with respect to cancer survivors’ ability to work, level of education, and type of cancer.  相似文献   

3.
4.
5.
Insect pollinators provide a crucial ecosystem service, but are under threat. Urban areas could be important for pollinators, though their value relative to other habitats is poorly known. We compared pollinator communities using quantified flower-visitation networks in 36 sites (each 1 km2) in three landscapes: urban, farmland and nature reserves. Overall, flower-visitor abundance and species richness did not differ significantly between the three landscape types. Bee abundance did not differ between landscapes, but bee species richness was higher in urban areas than farmland. Hoverfly abundance was higher in farmland and nature reserves than urban sites, but species richness did not differ significantly. While urban pollinator assemblages were more homogeneous across space than those in farmland or nature reserves, there was no significant difference in the numbers of rarer species between the three landscapes. Network-level specialization was higher in farmland than urban sites. Relative to other habitats, urban visitors foraged from a greater number of plant species (higher generality) but also visited a lower proportion of available plant species (higher specialization), both possibly driven by higher urban plant richness. Urban areas are growing, and improving their value for pollinators should be part of any national strategy to conserve and restore pollinators.  相似文献   

6.
Leslie Ries  Thomas D. Sisk 《Oikos》2010,119(10):1636-1642
For decades, researchers have categorized species as “edge‐loving” or “edge‐avoiding”, but recent studies that show inconsistencies in responses have called these labels into question and led to a sense that edge effects are idiosyncratic and difficult to understand. We suggest that species would be better categorized according to their sensitivity to edges, not the direction of observed responses because no species should be expected to show the same response to all edge types. Measures of edge sensitivity will apply widely across taxa and landscapes and allow metrics that are broadly comparable, making generalities easier to discern. Finally, while the direction of observed edge responses remains a critical (but largely understood) dynamic, most reported edge responses are neutral, so discovering when species are least likely to respond to edges will increase our understanding of edge ecology and associated fragmentation effects. We offer a case study that measures edge sensitivity of 15 butterfly species at 12 edge types. We found that sensitivity is weakly related to vulnerability to predation, but more importantly we show how our results generate new predictions about edge sensitivity that can be explored in future studies.  相似文献   

7.
Studies in experimental grasslands have extensively documented the effects of sown plant diversity on the colonization of new species, but the responses of the sown plant combinations themselves have rarely been investigated. We established experimental grasslands differing in species richness (1, 2, 4, 8, and 16) and functional group number and composition (1–4; legumes, grasses, small herbs, tall herbs), and we studied the changes in the abundance of sown species (residents) in both weeded and non-weeded subplots over a period of five years after sowing. The accumulation of new species through spontaneous colonization in the non-weeded treatment did not affect the number of resident species, but had increasingly negative effects over time on the cover of resident species and their aboveground biomass production at community level. Temporal stability of resident populations was lower and year-to-year changes in resident species composition were larger in non-weeded than in weeded subplots. Compositional dissimilarity between weeded and non-weeded treatments increased through time. These negative effects of the colonization of new species on the abundances and stability of resident populations depended on resident species identity and not on additional variation between different functional groups. The colonization of new species did not change the number of resident species emerging from seeds, but reduced seedling densities of residents. Colonization did not affect the structure of resident communities as measured by species evenness, functional trait diversity and mean trait values suggesting that colonization can destabilize the species composition of residents in terms of abundance while leaving them unchanged in terms of functional characteristics. Generally, negative impacts of colonizing species on residents which accelerated through time decreased with an increasing number of sown species. Sowing more diverse grassland mixtures increases their predictability in terms of ecosystem characteristics, which is important for ecological restoration and sustainable agriculture.  相似文献   

8.
9.
10.
A range of biodiversity metrics are available to assess the ecological integrity of aquatic ecosystems. However, performance varies considerably among different types of metrics and provides different information regarding ecosystem conditions, thus making difficult the selection of appropriate metrics for biomonitoring. The present study evaluated the robustness of six biodiversity metrics to assess environmental change and determine their utility as relevant indicators of ecosystem biodiversity and functionality. Traditional metrics such as species richness and Shannon diversity were considered along with alternative metrics such as functional diversity, size diversity and taxonomic distinctness. To that end, invertebrate assemblages in a river floodplain were used as a case study to evaluate the performance of metrics using Generalized Additive Models (GAM). GAM explained between eight and 49% of the variability in biodiversity. The regression models exhibited differences in the response of biodiversity indicators to environmental factors, suggesting that intermediate levels of turbidity and low salinity are conditions favouring increased biodiversity in the study area. Based on correlations among metrics and responses to primary environmental factors, it is concluded that Shannon and functional diversity, and rarefied species richness generated similar information regarding ecosystem conditions (i.e., the metrics were redundant); while size diversity and distinctness provided useful additional data characterizing ecosystem quality (i.e., the metrics were complementary). Functional diversity indicated not only number and dominance of species, but also each species functional role in the community, and was therefore the most informative biodiversity metric. Nevertheless, the use of a combination of metrics, for example functional and size diversity, and variation in taxonomic distinctness, provides complementary data that will serve to achieve a more thorough understanding of ecosystem structure and function, and response to primary environmental influences.  相似文献   

11.
Ecosystem services (ES) approaches to biodiversity conservation are currently high on the ecological research and policy agendas. However, despite a wealth of studies into biodiversity''s role in maintaining ES (B–ES relationships) across landscapes, we still lack generalities in the nature and strengths of these linkages. Reasons for this are manifold, but can largely be attributed to (i) a lack of adherence to definitions and thus a confusion between final ES and the ecosystem functions (EFs) underpinning them, (ii) a focus on uninformative biodiversity indices and singular hypotheses and (iii) top-down analyses across large spatial scales and overlooking of context-dependency. The biodiversity–ecosystem functioning (B–EF) field provides an alternate context for examining biodiversity''s mechanistic role in shaping ES, focusing on species'' characteristics that may drive EFs via multiple mechanisms across contexts. Despite acknowledgements of a need for B–ES research to look towards underlying B–EF linkages, the connections between these areas of research remains weak. With this review, we pull together recent B–EF findings to identify key areas for future developments in B–ES research. We highlight a means by which B–ES research may begin to identify how and when multiple underlying B–EF relationships may scale to final ES delivery and trade-offs.  相似文献   

12.
The intent of this paper is to outline a process by which we redefined an ambiguous behavioral category, rough-and-tumble play (R&T), using ethological and ethnographic methods (i.e., factor analyses, motivational/functional analyses, and interviews). Results suggest that sociometrically rejected and popular elementary school children have different concepts of R&T. For the former group, R&T and aggression seem to be interrelated and serve similar functions, while for the latter group R&T is a playful, social affiliative category. Interview results suggest that a cognitive processing difference between the groups may be at the root of this difference.  相似文献   

13.
What criteria should be used to select biodiversity indicators?   总被引:2,自引:0,他引:2  
The conservation of biodiversity is a major goal in nature conservation, but measuring the total biodiversity of a site or a region is not possible; thus there is a great demand for indicators to represent biodiversity. To be able to make use of indicators, criteria must first be established for their selection, and the degree to which the indicators meet the criteria must be tested. However, the purposes for which indicators are applied—and thus sometimes the criteria themselves—differ between ecological science and environmental policy. As transparency in choosing and testing suitable biodiversity indicators will optimize the results of an indicator, this article first aims to determine if there are common approaches in selecting biodiversity indicators in ecology and environmental policy. Second, we asked which criteria biodiversity indicators were scientifically tested against to determine their suitability. To answer these questions, we analyzed papers on biodiversity indicators referenced in the Web of Science. Our results demonstrate different patterns for selecting biodiversity indicators in the different fields of application. In ecology, the quality of indicators is mainly determined by a close relationship between indicator and indicandum (i.e., indicated phenomenon), while the relevance of an indicator for a given issue, e.g., reserve selection or an assessment of a certain impact, is of paramount importance for conservation policy. Surprisingly, few biodiversity indicators are empirically tested to determine if they meet the criteria by which they were purportedly chosen. We argue that this is due to the different conceptualizations of biodiversity indicators in science and environmental policy. Since the suitability of biodiversity indicators remains untested in many cases, our findings suggest room to make better use of indicators in ecology and environmental policy. As the results of ecological research are put to use to solve environmental problems, the selection of indicators for ecological research should correspond to a large extent with those used in environmental policy. Further, to assess the suitability of a biodiversity indicator, it should be tested against all of the criteria relevant for its selection.  相似文献   

14.
15.
Acta Biotheoretica - The concept of causal specificity is drawing considerable attention from philosophers of biology. It became the rationale for rejecting (and occasionally, accepting) a thesis...  相似文献   

16.
The minute (adult size 1.3–4.8 mm) land snail species of the family Diplommatinidae in the Fiji archipelago are revised based on historical material and modern (1998–99) collections targeting limestone outcrops on the largest island, Viti Levu, and several smaller islands in the Lau group. The forty-two species (including 30 new species) belong to the genera Moussonia Semper, 1865, Palaina Semper, 1865 and Diancta Martens, 1867, which are briefly characterized and keyed. The diagnostic structure of the inner lamellar system of each species is illustrated. All species except one are endemic to Fiji. In Viti Levu, the 12 localities surveyed each had 1–13 (average 5) species of Diplommatinidae; ten species were each found at a single site only. In the Lau islands, five islands were visited, with 1–4 species per island; four species are known from single islands. The number of historically known species not recollected in 1998–99 (7 species), the number of single-site occurrences (14 species), and the numerous islands — including limestone islands — that have not been surveyed at all, indicate that the 42 species of Diplommatinidae currently known from Fiji represent perhaps only half of the Fiji diplommatinid fauna. Such numbers approach the diplommatinid diversity of Palau (39 described and more than 60 undescribed species), and surpasses by far the diversity of other South Pacific archipelagos of comparable land area (New Caledonia, Vanuatu, Samoa).Nomenclatural acts: Lectotypes designated: Diplommatina fuscula, Diplommatina fuscula var. vitiana, Diplommatina godeffroyana, Diplommatina godeffroyana var. latecostata, Diplommatina tuberosa, Diplommatina martensi var. macrostoma, all Mousson, 1870. Neotypes designated: Diplommatina subregularis, Diplommatina ascendens, Diplommatina quadrata, all Mousson, 1870. New species: Diancta aurea sp. n., Diancta aurita sp. n., Diancta basiplana sp. n., Diancta controversa sp. n., Diancta densecostulata sp. n., Diancta dextra sp. n., Diancta dilatata sp. n., Diancta distorta sp. n., Diancta pulchella sp. n., Diancta rotunda sp. n., Diancta subquadrata sp. n., Diancta trilamellata sp. n., Moussonia acuta sp. n., Moussonia barkeri sp. n., Moussonia brodieae sp. n., Moussonia longipalatalis sp. n., Moussonia minutissima sp. n., Moussonia obesa sp. n., Moussonia polita sp. n., Moussonia uncinata sp. n., Moussonia vitianoides sp. n., Palaina alberti sp. n., Palaina flammulata sp. n., Palaina glabella sp. n., Palaina kitteli sp. n., Palaina labeosa sp. n., Palaina parietalis sp. n., Palaina sulcata sp. n., Palaina truncata sp. n., Palaina tuberosissima sp. n.  相似文献   

17.
What is mzXML good for?   总被引:1,自引:0,他引:1  
mzXML (extensible markup language) is one of the pioneering data formats for mass spectrometry-based proteomics data collection. It is an open data format that has benefited and evolved as a result of the input of many groups, and it continues to evolve. Due to its dynamic history, its structure, purpose and applicability have all changed with time, meaning that groups that have looked at the standard at different points during its evolution have differing impressions of the usefulness of mzXML. In discussing mzXML, it is important to understand what mzXML is not. First, mzXML does not capture the raw data. Second, mzXML is not sufficient for regulatory submission. Third, mzXML is not optimized for computation and, finally, mzXML does not capture the experiment design. In general, it is the authors' opinion that XML is not a panacea for bioinformatics or a substitute for good data representation, and groups that want to use mzXML (or other XML-based representations) directly for data storage or computation will encounter performance and scalability problems. With these limitations in mind, the authors conclude that mzXML is, nonetheless, an indispensable data exchange format for proteomics.  相似文献   

18.
19.
Personalized computational hemodynamics (CH) is a promising tool to clarify/predict the link between low density lipoproteins (LDL) transport in aorta, disturbed shear and atherogenesis. However, CH uses simplifying assumptions that represent sources of uncertainty. In particular, modelling blood-side to wall LDL transfer is challenged by the cumbersomeness of protocols needed to obtain reliable LDL concentration profile estimations. This paucity of data is limiting the establishment of rigorous CH protocols able to balance the trade-offs among the variety of in vivo data to be acquired, and the accuracy required by biological/clinical applications.In this study, we analyze the impact of LDL concentration initialization (initial conditions, ICs) and inflow boundary conditions (BCs) on CH models of LDL blood-to-wall transfer in aorta. Technically, in an image-based model of human aorta, two different inflow BCs are generated imposing subject-specific inflow 3D PC-MRI measured or idealized (flat) velocity profiles. For each simulated BC, four different ICs for LDL concentration are applied, imposing as IC the LDL distribution resulting from steady-state simulations with average conditions, or constant LDL concentration values.Based on CH results, we conclude that: (1) the imposition of realistic 3D velocity profiles as inflow BC reduces the uncertainty affecting the representation of LDL transfer; (2) different LDL concentration ICs lead to markedly different patterns of LDL transfer.Given that it is not possible to verify in vivo the proper LDL concentration initialization to be applied, we suggest to carefully set and unambiguously declare the imposed BCs and LDL concentration IC when modelling LDL transfer in aorta, in order to obtain reproducible and ultimately comparable results among different laboratories.  相似文献   

20.
Truth is threatened in our societies and one might wish that scientists should stand up for truth, but in order to do so, one needs to know what is truth and how it can be recognized. The oldest and most widely accepted concept of truth is the Correspondence Theory requesting a fit of propositions and reality. In the Coherence Theory truth is a consistent property of a whole system of propositions. In the Pragmatic Theory truth works in practical terms. Scientists have defined criteria to verify true statements by experiments and by the simplicity of theories. Aristotle proposed parsimony claiming the superiority of theories which derive from fewer hypotheses. David Hume suggested probability arguments to assess the force of evidence. Nicolai Hartmann elaborated a model based on the congruence of a priori logical arguments with a posteriori empirical observations. Karl Popper introduced the falsification of testable theories as a way to better theories. The analysis shows that scientific and medical research uses classical philosophical criteria of truth in their daily work. Humanities use different, hermeneutic criteria of truth. Finally, societies need for their coherence a dialectic approach to truth based on honest discussion of opposing views.  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