219 research outputs found

    Multi-object segmentation using coupled nonparametric shape and relative pose priors

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    We present a new method for multi-object segmentation in a maximum a posteriori estimation framework. Our method is motivated by the observation that neighboring or coupling objects in images generate configurations and co-dependencies which could potentially aid in segmentation if properly exploited. Our approach employs coupled shape and inter-shape pose priors that are computed using training images in a nonparametric multi-variate kernel density estimation framework. The coupled shape prior is obtained by estimating the joint shape distribution of multiple objects and the inter-shape pose priors are modeled via standard moments. Based on such statistical models, we formulate an optimization problem for segmentation, which we solve by an algorithm based on active contours. Our technique provides significant improvements in the segmentation of weakly contrasted objects in a number of applications. In particular for medical image analysis, we use our method to extract brain Basal Ganglia structures, which are members of a complex multi-object system posing a challenging segmentation problem. We also apply our technique to the problem of handwritten character segmentation. Finally, we use our method to segment cars in urban scenes

    Work-family trajectories across Europe: differences between social groups and welfare regimes

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    IntroductionWork and family trajectories develop and interact over the life course in complex ways. Previous studies drew a fragmented picture of these trajectories and had limited scope. We provide the most comprehensive study of early-to-midlife work-family trajectories to date.MethodsUsing retrospective data from waves 3 and 7 of the Survey of Health, Aging and Retirement in Europe (SHARE), we reconstructed work-family trajectories from age 15 to 49 among almost 80,000 individuals born between 1908 and 1967 across 28 countries. We applied multichannel sequence and cluster analysis to identify typical trajectories and multinomial logistic regression models to uncover their social composition.ResultsThe results revealed six common trajectories. The dominant and therefore standard trajectory represents continuous full-time employment with having a partner and children. Women, the lower educated and persons from conservative and liberal welfare regimes are underrepresented in this trajectory, whereas men, higher educated people and those from social-democratic, Eastern European and Baltic welfare regimes are overrepresented. The other trajectories denote a deviation from the standard one, integrating a non-standard form of work with standard family formation or vice versa. Mothers in a stable relationship generally work part-time or not at all. When mostly in full-time employment, women are more likely to be divorced. Lower educated persons are less likely to have work-family trajectories characterized by full-time work and a non-standard family, yet more likely to be non-employed for large parts of their life with standard family formation. Younger cohorts are underrepresented in non-employment trajectories, but overrepresented in part-time employment trajectories along with a partner and children as well as full-time employment trajectories with divorce. Individuals from Southern European and liberal regimes are more likely to be non-working and self-employed partnered parents and those from social-democratic regimes are more likely to be full-time employed divorced parents. We also found pronounced gender differences in how educational level, birth cohort and welfare regime are associated with work-family trajectories from early to midlife.DiscussionOur findings highlight the socially stratified nature of earlier-life work-family trajectories in Europe. Potential implications for inequalities in later life are discussed

    Trade flows, exchange rate uncertainty and financial depth: evidence from 28 emerging countries

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    This paper investigates the effects of real exchange rate uncertainty on manufactures exports from 28 emerging economies, representing 82\% of all developing country manufactures exports, and explores the sources of heterogeneity in the uncertainty effects by controlling for the direction of trade (South-North or South-South), and the level of financial development of the exporting country. The empirical results show that for more than half of the countries the uncertainty effect is unidirectional, either South-South or South-North, and the median impact is negative. In addition, while we find that financial development augments trade, exchange rate shocks can negate this effect. Last but not the least, trade among developing economies improves export growth under exchange rate shocks

    Trade flows, exchange rate uncertainty and financial depth: evidence from 28 emerging countries

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    This paper investigates the effects of real exchange rate uncertainty on manufactures exports from 28 emerging economies, representing 82\% of all developing country manufactures exports, and explores the sources of heterogeneity in the uncertainty effects by controlling for the direction of trade (South-North or South-South), and the level of financial development of the exporting country. The empirical results show that for more than half of the countries the uncertainty effect is unidirectional, either South-South or South-North, and the median impact is negative. In addition, while we find that financial development augments trade, exchange rate shocks can negate this effect. Last but not the least, trade among developing economies improves export growth under exchange rate shocks

    Effect of atorvastatin on spermatogenesis in rats: A stereological study

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    Purpose: To investigate the effects of oral atorvastatin on spermatogenesis in a rat model.Methods: Rats were equally assigned into control and study groups, the latter receiving atorvastatin (20 mg/kg/day). At the end of 12 weeks, spermatogenetic activity was evaluated using stereological and optical fractionator methods. Serum follicle-stimulating hormone (FSH), total testosterone (TT), and luteinizing hormone (LH) levels were measured using micro–ELISA kits. Total cholesterol, triglyceride (TG), low-density lipoprotein cholesterol (LDL - C), and high-density lipoprotein cholesterol levels were also measured by enzymatic colorimetric assays.Results: Testicular stereological analysis revealed that atorvastatin reduced Sertoli cell numbers (p < 0.001), spermatogonia (p < 0.001), spermatocytes (p < 0.001), and seminiferous tubule diameters (p < 0.001). LDL – C (p = 0.01) and TG (p = 0.01) values were significantly lower in the study group compared with the control group. There was no significant difference in FSH (p = 0.44), LH (p = 0.48),and TT (p = 0.06) levels between the groups.Conclusion: The findings show that atorvastatin causes deleterious effects on rat spermatogenesis. It should therefore be used with caution in clinical practice owing to its potential adverse effects, especially on male fertility. Keywords: Statin, Atorvastatin, Spermatogenesis, Stereology, Testi

    Obstructive sleep apnea syndrome is associated with impaired pulmonary artery distensibility and right ventricular systolic dysfunction

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    Conclusion: PAD is a significant tool to evaluate pulmonary vasculature stiffening and is well correlated with disease severity in OSAS. Further, impaired PAD may lead to RV systolic dysfunction

    Biogasification and combustion reactions of Turkish lignites: adsorption behavior and biogasification of Soma lignite and co-combustion of Beypazari lignite with biomass

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    In this study, our primary objective is to understand CBM capacity of the Soma coal basin. For this reason, porosity of the coal samples must be determined. Usually, surface area and the porosity of the materials can be calculated through the N2 physical sorption experiment, in this method entire relative pressure range (10-8 to 1) can be analyzed without using high pressure equipments. However, for microporous materials like carbon materials and zeolites physical sorption occurs at very low relative pressure ranges (10-8 to 10-3) and experiments that are conducted with N2 are less reliable due to the low diffusion rate and adsorption equilibrium in the pores between 0,5 to 1 nm at 77 K. It is also known that specifically for carbon materials experiments that are conducted at low temperatures such as N2 sorption causes pore shrinkage that leads to the low sorption equilibrium

    Creative destruction in science

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    Drawing on the concept of a gale of creative destruction in a capitalistic economy, we argue that initiatives to assess the robustness of findings in the organizational literature should aim to simultaneously test competing ideas operating in the same theoretical space. In other words, replication efforts should seek not just to support or question the original findings, but also to replace them with revised, stronger theories with greater explanatory power. Achieving this will typically require adding new measures, conditions, and subject populations to research designs, in order to carry out conceptual tests of multiple theories in addition to directly replicating the original findings. To illustrate the value of the creative destruction approach for theory pruning in organizational scholarship, we describe recent replication initiatives re-examining culture and work morality, working parents\u2019 reasoning about day care options, and gender discrimination in hiring decisions. Significance statement It is becoming increasingly clear that many, if not most, published research findings across scientific fields are not readily replicable when the same method is repeated. Although extremely valuable, failed replications risk leaving a theoretical void\u2014 reducing confidence the original theoretical prediction is true, but not replacing it with positive evidence in favor of an alternative theory. We introduce the creative destruction approach to replication, which combines theory pruning methods from the field of management with emerging best practices from the open science movement, with the aim of making replications as generative as possible. In effect, we advocate for a Replication 2.0 movement in which the goal shifts from checking on the reliability of past findings to actively engaging in competitive theory testing and theory building. Scientific transparency statement The materials, code, and data for this article are posted publicly on the Open Science Framework, with links provided in the article

    Examining the generalizability of research findings from archival data

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    This initiative examined systematically the extent to which a large set of archival research findings generalizes across contexts. We repeated the key analyses for 29 original strategic management effects in the same context (direct reproduction) as well as in 52 novel time periods and geographies; 45% of the reproductions returned results matching the original reports together with 55% of tests in different spans of years and 40% of tests in novel geographies. Some original findings were associated with multiple new tests. Reproducibility was the best predictor of generalizability—for the findings that proved directly reproducible, 84% emerged in other available time periods and 57% emerged in other geographies. Overall, only limited empirical evidence emerged for context sensitivity. In a forecasting survey, independent scientists were able to anticipate which effects would find support in tests in new samples
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