98 resultados para habitat specificity

em BORIS: Bern Open Repository and Information System - Berna - Suiça


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Studies of intraspecific morphological variation in fishes have traditionally focused on freshwater rather than marine species. In addition, such studies typically focus on adults, although causes and intensities of selective pressures most likely vary through an individual’s lifetime. In this study, body and head shape of a marine species, shiner perch Cymatogaster aggregata Gibbons were compared among localities along the Pacific Northwest coast of North America. Evidence was found for intraspecific variation in ontogenetic allometry, and for a closer correlation of body shape with environment rather than geographical proximity. This correlation with environment was more evident in younger fish, thereby demonstrating the importance of analysing multiple life stages. A common garden experiment suggests both environmental and genetic bases for the observed differences. Recognizing intraspecific ecomorphological complexity and its specificity to habitat and/or life stage can have important consequences for understanding the role of local adaptation and population dynamics in macroecology.

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Host determinants of HIV-1 viral tropism include factors from producer cells that affect the efficiency of productive infection and factors in target cells that block infection after viral entry. TRIM5 restricts HIV-1 infection at an early post-entry step through a mechanism associated with rapid disassembly of the retroviral capsid. Topoisomerase I (TOP1) appears to play a role in HIV-1 viral tropism by incorporating into or otherwise modulating virions affecting the efficiency of a post-entry step, as the expression of human TOP1 in African Green Monkey (AGM) virion-producing cells increased the infectivity of progeny virions by five-fold. This infectivity enhancement required human TOP1 residues 236 and 237 as their replacement with the AGM counterpart residues abolished the infectivity enhancement. Our previous studies showed that TOP1 interacts with BTBD1 and BTBD2, two proteins which co-localize with the TRIM5 splice variant TRIM5 in cytoplasmic bodies. Because BTBD1 and BTBD2 interact with one HIV-1 viral tropism factor, TOP1, and co-localize with a splice variant of another, we investigated the potential involvement of BTBD1 and BTBD2 in HIV-1 restriction.

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PURPOSE: The purpose of our study was to retrospectively evaluate the specificity, sensitivity and accuracy of computed tomography (CT), digital radiography (DR) and low-dose linear slit digital radiography (LSDR, Lodox(®)) in the detection of internal cocaine containers. METHODS: Institutional review board approval was obtained. The study collectively consisted of 83 patients (76 males, 7 females, 16-45 years) suspected of having incorporated cocaine drug containers. All underwent radiological imaging; a total of 135 exams were performed: nCT=35, nDR=70, nLSDR=30. An overall calculation of all "drug mules" and a specific evaluation of body packers, pushers and stuffers were performed. The gold standard was stool examination in a dedicated holding cell equipped with a drug toilet. RESULTS: There were 54 drug mules identified in this study. CT of all drug carriers showed the highest diagnostic accuracy 97.1%, sensitivity 100% and specificity 94.1%. DR in all cases was 71.4% accurate, 58.3% sensitive and 85.3% specific. LSDR of all patients with internal cocaine was 60% accurate, 57.9% sensitive and 63.4% specific. CONCLUSIONS: CT was the most accurate test studied. Therefore, the detection of internal cocaine drug packs should be performed by CT, rather than by conventional X-ray, in order to apply the most sensitive exam in the medico-legal investigation of suspected drug carriers. Nevertheless, the higher radiation applied by CT than by DR or LSDR needs to be considered. Future studies should include evaluation of low dose CT protocols in order to address germane issues and to reduce dosage.

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P>1. There are a number of models describing population structure, many of which have the capacity to incorporate spatial habitat effects. One such model is the source-sink model, that describes a system where some habitats have a natality that is higher than mortality (source) and others have a mortality that exceeds natality (sink). A source can be maintained in the absence of migration, whereas a sink will go extinct. 2. However, the interaction between population dynamics and habitat quality is complex, and concerns have been raised about the validity of published empirical studies addressing source-sink dynamics. In particular, some of these studies fail to provide data on survival, a significant component in disentangling a sink from a low quality source. Moreover, failing to account for a density-dependent increase in mortality, or decrease in fecundity, can result in a territory being falsely assigned as a sink, when in fact, this density-dependent suppression only decreases the population size to a lower level, hence indicating a 'pseudo-sink'. 3. In this study, we investigate a long-term data set for key components of territory-specific demography (mortality and reproduction) and their relationship to habitat characteristics in the territorial, group-living Siberian jay (Perisoreus infaustus). We also assess territory-specific population growth rates (r), to test whether spatial population dynamics are consistent with the ideas of source-sink dynamics. 4. Although average mortality did not differ between sexes, habitat-specific mortality did. Female mortality was higher in older forests, a pattern not observed in males. Male mortality only increased with an increasing amount of open areas. Moreover, reproductive success was higher further away from human settlement, indicating a strong effect of human-associated nest predators. 5. Averaged over all years, 76% of the territories were sources. These territories generally consisted of less open areas, and were located further away from human settlement. 6. The source-sink model provides a tool for modelling demography in distinct habitat patches of different quality, which can aid in identifying key habitats within the landscape, and thus, reduce the risk of implementing unsound management decisions.

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Among various groups of fishes, a shift in peak wavelength sensitivity has been correlated with changes in their photic environments. The genus Sebastes is a radiation of marine fish species that inhabit a wide range of depths from intertidal to over 600 m. We examined 32 species of Sebastes for evidence of adaptive amino acid substitution at the rhodopsin gene. Fourteen amino acid positions were variable among these species. Maximum likelihood analyses identify several of these to be targets of positive selection. None of these correspond to previously identified critical amino acid sites, yet they may in fact be functionally important. The occurrence of independent parallel changes at certain amino acid positions reinforces this idea. Reconstruction of habitat depths of ancestral nodes in the phylogeny suggests that shallow habitats have been colonized independently in different lineages. The evolution of rhodopsin appears to be associated with changes in depth, with accelerated evolution in lineages that have had large changes in depth.

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Palestinian refugees registered with UNRWA and their housing conditions are officially characterized by a “ temporary status” , a situation which has lasted the past sixty years. This article explores this time-paradox by focusing on the host governments’ and UNRWA’s policies affecting the refugees’ housing conditions. After having reviewed available literature, this contribution analyses the current housing situation. Drawing on data from a recent survey, the authors provide insights on areas where intervention is needed. In all UNRWA’s fields of operation, overcrowding, lack of public spaces, humidity and structural defects are the main sources of housing discomfort that camp refugees endure. Host countries’ restrictions as well as the incapacity or unwillingness of larger urban municipalities to incorporate refugee camps in their master plans are among the main obstacles to the refugees’ housing development. Rehabilitation and self-help re-housing programs may offer substantial incentives for housing improvement. The success of such programs depends, among several factors, on the host governments’ good will to provide UNRWA with authorizations, financial support, and land, as well as on the capacity of involving the refugee communities in projects’ planning and implementation.

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Background Serologic testing algorithms for recent HIV seroconversion (STARHS) provide important information for HIV surveillance. We have shown that a patient's antibody reaction in a confirmatory line immunoassay (INNO-LIATM HIV I/II Score, Innogenetics) provides information on the duration of infection. Here, we sought to further investigate the diagnostic specificity of various Inno-Lia algorithms and to identify factors affecting it. Methods Plasma samples of 714 selected patients of the Swiss HIV Cohort Study infected for longer than 12 months and representing all viral clades and stages of chronic HIV-1 infection were tested blindly by Inno-Lia and classified as either incident (up to 12 m) or older infection by 24 different algorithms. Of the total, 524 patients received HAART, 308 had HIV-1 RNA below 50 copies/mL, and 620 were infected by a HIV-1 non-B clade. Using logistic regression analysis we evaluated factors that might affect the specificity of these algorithms. Results HIV-1 RNA <50 copies/mL was associated with significantly lower reactivity to all five HIV-1 antigens of the Inno-Lia and impaired specificity of most algorithms. Among 412 patients either untreated or with HIV-1 RNA ≥50 copies/mL despite HAART, the median specificity of the algorithms was 96.5% (range 92.0-100%). The only factor that significantly promoted false-incident results in this group was age, with false-incident results increasing by a few percent per additional year. HIV-1 clade, HIV-1 RNA, CD4 percentage, sex, disease stage, and testing modalities exhibited no significance. Results were similar among 190 untreated patients. Conclusions The specificity of most Inno-Lia algorithms was high and not affected by HIV-1 variability, advanced disease and other factors promoting false-recent results in other STARHS. Specificity should be good in any group of untreated HIV-1 patients.

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To retrospectively assess the diagnostic sensitivity of 45° Dunn view and cross-table lateral radiographs for the assessment of cam deformity by comparison with radial MRI.