30 research outputs found

    Adaptive Traits Are Maintained on Steep Selective Gradients despite Gene Flow and Hybridization in the Intertidal Zone

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    Gene flow among hybridizing species with incomplete reproductive barriers blurs species boundaries, while selection under heterogeneous local ecological conditions or along strong gradients may counteract this tendency. Congeneric, externally-fertilizing fucoid brown algae occur as distinct morphotypes along intertidal exposure gradients despite gene flow. Combining analyses of genetic and phenotypic traits, we investigate the potential for physiological resilience to emersion stressors to act as an isolating mechanism in the face of gene flow. Along vertical exposure gradients in the intertidal zone of Northern Portugal and Northwest France, the mid-low shore species Fucus vesiculosus, the upper shore species Fucus spiralis, and an intermediate distinctive morphotype of F. spiralis var. platycarpus were morphologically characterized. Two diagnostic microsatellite loci recovered 3 genetic clusters consistent with prior morphological assignment. Phylogenetic analysis based on single nucleotide polymorphisms in 14 protein coding regions unambiguously resolved 3 clades; sympatric F. vesiculosus, F. spiralis, and the allopatric (in southern Iberia) population of F. spiralis var. platycarpus. In contrast, the sympatric F. spiralis var. platycarpus (from Northern Portugal) was distributed across the 3 clades, strongly suggesting hybridization/introgression with both other entities. Common garden experiments showed that physiological resilience following exposure to desiccation/heat stress differed significantly between the 3 sympatric genetic taxa; consistent with their respective vertical distribution on steep environmental clines in exposure time. Phylogenetic analyses indicate that F. spiralis var. platycarpus is a distinct entity in allopatry, but that extensive gene flow occurs with both higher and lower shore species in sympatry. Experimental results suggest that strong selection on physiological traits across steep intertidal exposure gradients acts to maintain the 3 distinct genetic and morphological taxa within their preferred vertical distribution ranges. On the strength of distributional, genetic, physiological and morphological differences, we propose elevation of F. spiralis var. platycarpus from variety to species level, as F. guiryi

    Pure seminoma: A review and update

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    Pure seminoma is a rare pathology of the young adult, often discovered in the early stages. Its prognosis is generally excellent and many therapeutic options are available, especially in stage I tumors. High cure rates can be achieved in several ways: standard treatment with radiotherapy is challenged by surveillance and chemotherapy. Toxicity issues and the patients' preferences should be considered when management decisions are made. This paper describes firstly the management of primary seminoma and its nodal involvement and, secondly, the various therapeutic options according to stage

    Speciation, introgressive hybridization and nonlinear rate of molecular evolution in flycatchers.

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    Evolutionary history of Muscicapidae flycatchers is inferred from nuclear and mitochondrial DNA (mtDNA) sequence comparisons and population genetic analysis of nuclear and mtDNA markers. Phylogenetic reconstruction based on sequences from the two genomes yielded similar trees with respect to the order at which the species split off. However, the genetic distances fitted a nonlinear, polynomial model reflecting diminishing divergence rate of the mtDNA sequences compared to the nuclear DNA sequences. This could be explained by Haldane's rule because genetic isolation might evolve more rapidly on the mitochondrial rather than the nuclear genome in birds. This is because hybrid sterility of the heterogametic sex (females) would predate that of the homogametic sex (males), leading to sex biased introgression of nuclear genes. Analyses of present hybrid zones of pied (Ficedula hypoleuca) and collared flycatchers (F. albicollis) may indicate a slight sexual bias in rate of introgression, but the introgression rates were too low to allow proper statistical analyses. It is suggested, however, that the observed deviation from linearity can be explained by a more rapid mutational saturation of the mtDNA sequences than of the nuclear DNA sequences, as supported by analyses of third codon position transversions at two protein coding mtDNA genes. A phylogeographic scenario for the black and white flycatcher species is suggested based on interpretation of the genetic data obtained. Four species appear to have diverged from a common ancestor relatively simultaneously during the Pleistocene. After the last glaciation period, pied and collared flycatchers expanded their breeding ranges and eventually came into secondary contact in Central and Eastern Europe and on the Baltic Isles

    A systematic review of quality of life research in medicine and health sciences

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    PURPOSE: Quality of life (QOL) is an important concept in the field of health and medicine. QOL is a complex concept that is interpreted and defined differently within and between disciplines, including the fields of health and medicine. The aims of this study were to systematically review the literature on QOL in medicine and health research and to describe the country of origin, target groups, instruments, design, and conceptual issues. METHODS: A systematic review was conducted to identify research studies on QOL and health-related quality of life (HRQOL). The databases Scopus, which includes Embase and MEDLINE, CINAHL, and PsycINFO were searched for articles published during one random week in November 2016. The ten predefined criteria of Gill and Feinstein were used to evaluate the conceptual and methodological rigor. RESULTS: QOL research is international and involves a variety of target groups, research designs, and QOL measures. According to the criteria of Gill and Feinstein, the results show that only 13% provided a definition of QOL, 6% distinguished QOL from HRQOL. The most frequently fulfilled criteria were: (i) stating the domains of QOL to be measured; (ii) giving a reason for choosing the instruments used; and (iii) aggregating the results from multiple items. CONCLUSION: QOL is an important endpoint in medical and health research, and QOL research involves a variety of patient groups and different research designs. Based on the current evaluation of the methodological and conceptual clarity of QOL research, we conclude that the majority QOL studies in health and medicine have conceptual and methodological challenges.status: publishe

    Evolution of single-particle structure near the N=20 island of inversion

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    The single-particle properties of 29Mg have been investigated via a measurement of the 28Mg(d,p)29Mg reaction, in inverse kinematics, using the ISOLDE Solenoidal Spectrometer. The negative-parity intruder states from the f p shell have been identified and used to benchmark modern shell-model calculations. The systematic data on the single-particle centroids along the N = 17 isotones show good agreement with shell-model predictions in describing the observed trends from stability toward 25O. However, there is also evidence that the effect of the finite geometry of the nuclear potential is playing a role on the behavior of the p orbitals near the particle-emission threshold.status: Published onlin

    Farm-Level Characteristics of Southern Nebraska Farms/Ranches with Annually-Planted Crops

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    The information presented in this report represents data collected from farming and ranching operations in the southern two tiers of counties in Nebraska. This study was based on a random sample of 15 1 southern Nebraska farms that have annually-planted crop acreage. Information was obtained for the 1997 crop year. This data set is referred to as the MSU/UNL survey data. From the MSU/UNL survey data, the average size of the farming operations in the survey, in 1997, was 1,3 16 acres. Of these, 856 acres were planted to annual crops, and the remaining 460 acres included 61 acres in fallow, 29 acres in hay, 287 acres in range and pasture, 28 acres in CRP, and 55 acres in other uses. Operation size was largest in the west, due mostly to a large number of range and pasture land acres per operator. Average farm size decreased in the east as range and pasture land acres and acres fallowed per farm both decreased. Acreage planted to annual crops was similar from east to west. Irrigated and dryland grain corn was the predominant crop grown in the survey area. Other major crops included soybeans, sorghum, and winter wheat. An estimated 44 percent of the respondents\u27 cropland acreage was dedicated to corn production. Other annual crops included soybean (21 percent of cropland acreage), sorghum (10 percent of cropland acreage), winter wheat (12 percent of cropland acreage), and minor crops (4 percent of cropland acreage) with most of the remaining cropland in fallow. The distribution of these crops varied across the southern tier of Nebraska counties. Winter wheat was most common in the west and soybean was more prevalent in the east. About 65 percent of total cropland acreage reported was dryland while the remaining 35 percent was irrigated. Significantly more irrigation takes place in the central area. Two-thirds of the operations surveyed reported some type of livestock enterprise. Cattle were the most common type of livestock reported, followed by hogs and sheep. Breeding cattle numbers were greater than feeder cattle numbers. Dairy cattle were rarely reported except in the eastern counties. Producers in the central and eastern counties also reported hog production, with feeder hogs greatly outnumbering breeding animals. Comparisons of acres planted and crop yields from the MSU/UNL survey data to data collected by Nebraska Agricultural Statistics Service (NASS), for the same year, show little differences. Most estimates are within 2 percentage points of each other
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