959 resultados para Classical geography


Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The classical approach to predicting the geographical extent of species invasions consists of training models in the native range and projecting them in distinct, potentially invasible areas. However, recent studies have demonstrated that this approach could be hampered by a change of the realized climatic niche, allowing invasive species to spread into habitats in the invaded ranges that are climatically distinct from those occupied in the native range. We propose an alternative approach that involves fitting models with pooled data from all ranges. We show that this pooled approach improves prediction of the extent of invasion of spotted knapweed (Centaurea maculosa) in North America on models based solely on the European native range. Furthermore, it performs equally well on models based on the invaded range, while ensuring the inclusion of areas with similar climate to the European niche, where the species is likely to spread further. We then compare projections from these models for 2080 under a severe climate warming scenario. Projections from the pooled models show fewer areas of intermediate climatic suitability than projections from the native or invaded range models, suggesting a better consensus among modelling techniques and reduced uncertainty.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Classical planning has been notably successful in synthesizing finite plans to achieve states where propositional goals hold. In the last few years, classical planning has also been extended to incorporate temporally extended goals, expressed in temporal logics such as LTL, to impose restrictions on the state sequences generated by finite plans. In this work, we take the next step and consider the computation of infinite plans for achieving arbitrary LTL goals. We show that infinite plans can also be obtained efficiently by calling a classical planner once over a classical planning encoding that represents and extends the composition of the planningdomain and the B¨uchi automaton representingthe goal. This compilation scheme has been implemented and a number of experiments are reported.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this paper is to test formally the classical business cycle hypothesis, using data from industrialized countries for the time period since 1960. The hypothesis is characterized by the view that the cyclical structure in GDP is concentrated in the investment series: fixed investment has typically a long cycle, while the cycle in inventory investment is shorter. To check the robustness of our results, we subject the data for 15 OECD countries to a variety of detrending techniques. While the hypothesis is not confirmed uniformly for all countries, there is a considerably high number for which the data display the predicted pattern. None of the countries shows a pattern which can be interpreted as a clear rejection of the classical hypothesis.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: Despite the importance of respiration and hyperventilation in anxiety disorders, research on breathing disturbances associated with hyperventilation is rare in the field of music performance anxiety (MPA, also known as stage fright). The only comparable study in this area reported a positive correlation between negative feelings of MPA and hyperventilation complaints during performance. The goals of this study were (a) to extend these previous findings to the period before performance, (b) to test whether a positive correlation also exists between hyperventilation complaints and the experience of stage fright as a problem, (c) to investigate instrument-specific symptom reporting, and (d) to confirm gender differences in negative feelings of MPA and hyperventilation complaints reported in other studies. Methods: We assessed 169 university students of classical music with a questionnaire comprising: the State-Trait Anxiety Inventory for negative feelings of MPA, the Nijmegen Questionnaire for hyperventilation complaints, and a single item for the experience of stage fright as a problem. Results: We found a significant positive correlation between hyperventilation complaints and negative feelings of MPA before performance and a significant positive correlation between hyperventilation complaints and the experience of stage fright as a problem. Wind musicians/singers reported a significantly higher frequency of respiratory symptoms than other musicians. Furthermore, women scored significantly higher on hyperventilation complaints and negative feelings of MPA. Conclusion: These results further the findings of previous reports by suggesting that breathing disturbances associated with hyperventilation may play a role in MPA prior to going on stage. Experimental studies are needed to confirm whether hyperventilation complaints associated with negative feelings of MPA manifest themselves at the physiological level. (C) 2010 Elsevier Inc. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Understanding the genetic structure of human populations is of fundamental interest to medical, forensic and anthropological sciences. Advances in high-throughput genotyping technology have markedly improved our understanding of global patterns of human genetic variation and suggest the potential to use large samples to uncover variation among closely spaced populations. Here we characterize genetic variation in a sample of 3,000 European individuals genotyped at over half a million variable DNA sites in the human genome. Despite low average levels of genetic differentiation among Europeans, we find a close correspondence between genetic and geographic distances; indeed, a geographical map of Europe arises naturally as an efficient two-dimensional summary of genetic variation in Europeans. The results emphasize that when mapping the genetic basis of a disease phenotype, spurious associations can arise if genetic structure is not properly accounted for. In addition, the results are relevant to the prospects of genetic ancestry testing; an individual's DNA can be used to infer their geographic origin with surprising accuracy-often to within a few hundred kilometres.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Epstein-Barr virus (EBV)-infected B cells with Reed-Sternberg-like cell (RS) features may occur in peripheral T-cell lymphomas (PTCLs), especially in angioimmunoblastic T-cell lymphoma. Here, we report 5 patients presenting with lymphadenopathy whose first biopsies demonstrated nodular lymphoid proliferations containing scattered CD30, CD15, EBV Hodgkin and Reed-Sternberg-like cells, which led to an initial diagnosis of lymphocyte-rich classical Hodgkin lymphoma. However, the uncommon clinical features and/or the occurrence of relapse as PTCL prompted review of the biopsies with expanded immunohistologic and molecular studies and revision of the diagnoses to follicular variant of PTCL (F-PTCL). All cases had atypical small to medium-sized CD3 T cells that expressed CD10 (4/5) and the follicular helper T-cell (TFH) antigens BCL6, PD1, CXCL13, and ICOS. All demonstrated clonal T cells with a similar pattern in multiple samples from 4 patients. In 2 cases, flow cytometry demonstrated circulating lymphocytes with an abnormal sCD3, CD4, ICOS immunophenotype. Two patients had a skin rash at presentation, and 1 had B symptoms. Two of the 4 patients treated with polychemotherapy are alive at 3 and 6 years after first diagnosis. These cases highlight how some F-PTCLs may closely mimic lymphocyte-rich classical Hodgkin lymphoma requiring careful assessment of the T cells before rendering the latter diagnosis. The functional properties of TFH cells might lead to the presence of EBV-positive B blasts with RS-like features in TFH-derived PTCL such as angioimmunoblastic T-cell lymphoma and F-PTCL.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this paper is to test formally the classical business cyclehypothesis, using data from industrialized countries for the timeperiod since 1960. The hypothesis is characterized by the view that the cyclical structure in GDP is concentrated in the investment series: fixed investment has typically a long cycle, while the cycle in inventory investment is shorter. To check the robustness of our results, we subject the data for 15 OECD countries to a variety of detrending techniques. While the hypothesis is not confirmed uniformly for all countries, there is a considerably high number for which the data display the predicted pattern. None of the countries shows a pattern which can be interpreted as a clear rejection of the classical hypothesis.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper proposes a common and tractable framework for analyzingdifferent definitions of fixed and random effects in a contant-slopevariable-intercept model. It is shown that, regardless of whethereffects (i) are treated as parameters or as an error term, (ii) areestimated in different stages of a hierarchical model, or whether (iii)correlation between effects and regressors is allowed, when the sameinformation on effects is introduced into all estimation methods, theresulting slope estimator is also the same across methods. If differentmethods produce different results, it is ultimately because differentinformation is being used for each methods.

Relevância:

20.00% 20.00%

Publicador: