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Latter Analyses (latter + analysis)

Distribution by Scientific Domains

Humanities and Social Sciences	50%

Selected Abstracts

A probability-based analysis of temporal and spatial co-occurrence in grassland birds

JOURNAL OF BIOGEOGRAPHY, Issue 12 2006
Joseph A. Veech
Abstract Aim, To test for non-random co-occurrence in 36 species of grassland birds using a new metric and the C -score. The analysis used presence,absence data of birds distributed among 305 sites (or landscapes) over a period of 35 years. This analysis departs from traditional analyses of species co-occurrence in its use of temporal data and of individual species' probabilities of occurrence to derive analytically the expected co-occurrence between paired species. Location, Great Plains region, USA. Methods, Presence,absence data for the bird species were obtained from the North American Breeding Bird Survey. The analysis was restricted to species pairs whose geographic ranges overlapped. Each of 541 species pairs was classified as a positive, negative, or non-significant association depending on the mean difference between the observed and expected frequencies of co-occurrence over the 35-year time-span. Results, Of the 541 species pairs that were examined, 202 to 293 (37,54%) were positively associated, depending on which of two null models was used. However, only a few species pairs (<5%) were negatively associated. An additional 89 species pairs did not have overlapping ranges and hence represented de facto negative associations. The results from analyses based on C -scores generally agreed with the analyses based on the difference between observed and expected co-occurrence, although the latter analyses were slightly more powerful. Main conclusions, Grassland birds within the Great Plains region are primarily distributed among landscapes either independently or in conjunction with one another. Only a few species pairs exhibited repulsed or segregated distributions. This indicates that the shared preference for grassland habitat may be more important in producing coexistence than are negative species interactions in preventing it. The large number of non-significant associations may represent random associations and thereby indicate that the presence/absence of other grassland bird species may have little effect on whether a given focal species is also found within the landscape. In a broader context, the probability-based approach used in this study may be useful in future studies of species co-occurrence. [source]

Phenotypical and functional analysis of T cells in periodontitis

JOURNAL OF PERIODONTAL RESEARCH, Issue 4 2001
M. D. A. Petit
To explore aspects of cellular immune responses in the pathogenesis of periodontitis we analyzed phenotype and function of peripheral T cells. Two groups of subjects participated: one group consisted of 10 highly susceptible patients with severe periodontitis (mean age 29 years) and a control group consisted of 10 age, gender and race matched subjects with gingivitis. From all subjects peripheral blood was collected. The results showed that the numbers of CD3+, CD4+ and CD8+ T cells as well as the CD4/CD8 ratio, and the proliferative capacity of T cells, were not different between the two groups of subjects. Also, proportions of naive and memory T cells for both the CD4+ and CD8+ subpopulations were not different. Functional heterogeneity within the CD4+ and CD8+ T cell compartments was determined by intracellular analysis of interferon- ,(IFN- ,) and interleukin-4 (IL-4) production. On the basis of these latter analyses among CD4+ and CD8+ cells, T helper (Th) 1 or Th2 function and T cytotoxic (Tc) 1 or Tc2 function, respectively, could be deduced. No significant differences in proportions of CD4+ and CD8+ T cells positive for intracellular IFN- , or IL-4 were observed between periodontitis patients and gingivitis controls; however a higher level of intracellular IL-4 in CD8+ T cells was seen in periodontitis patients. This might indicate that there is a shift towards a Tc2 function within the CD8+ T cell subpopulation. The current explorative study suggests that further research into the role of CD8+T cells in the pathogenesis of periodontitis is warranted. [source]

Identification of differentially expressed root genes upon rhizomania disease

MOLECULAR PLANT PATHOLOGY, Issue 6 2008
LAURE SCHMIDLIN
SUMMARY Rhizomania is one of the most devastating sugar beet diseases. It is caused by Beet necrotic yellow vein virus (BNYVV), which induces abnormal rootlet proliferation. To understand better the physiological and molecular basis of the disorder, transcriptome analysis was performed by restriction fragment differential display polymerase chain reaction (RFDD-PCR), which provided differential gene expression profiles between non-infected and infected sugar beet roots. Two distinct viral isolates were used to detect specific or general virus-induced genes. Differentially expressed genes were selected and identified by sequence analysis, followed by reverse Northern and reverse transcriptase PCR experiments. These latter analyses of different plants (Beta vulgaris and Beta macrocarpa) infected under distinct standardized conditions revealed specific and variable expressions. Candidate genes were linked to cell development, metabolism, defence signalling and oxidative stress. In addition, the expression of already characterized genes linked to defence response (pathogenesis-related protein genes), auxin signalling and cell elongation was also studied to further examine some aspects of the disease. Differential expression was retrieved in both B. vulgaris and B. macrocarpa. However, some candidate genes were found to be deregulated in only one plant species, suggesting differential response to BNYVV or specific responses to the BNYVV vector. [source]

VIII,Epistemic Deference: The Case of Chance

PROCEEDINGS OF THE ARISTOTELIAN SOCIETY (HARDBACK), Issue 1pt2 2007
James M. Joyce
Epistemic deference is the phenomenon in which one person uses the deliverances of some information source, perhaps the opinions of another person, as a model for what to believe. The paper aims to clarify the nature of epistemic deference in probabilistic contexts, to explain the conditions under which deference is appropriate, and to examine deference to objective chances, as epitomized in David Lewis's Principal Principle. This latter analysis will show, in contrast with views that portray chance as an ideal inductive logician with total recall, that our deference to chance is grounded in contingent limitations on our ability to access information and our recognition that the physical probabilities that instantiate the actual chances codify all the types of information that humans are able to possess. [source]