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  • 1
    In: PLoS ONE, 2017, Vol.12(2)
    Description: Costly signaling theory provides an explanation for why humans are willing to a pay a premium for conspicuous products such as luxury brand-labeled clothing or conspicuous environmentally friendly cars. According to the theory, the extra cost of such products is a signal of social status and wealth and leads to advantages in social interactions for the signaler. A previous study found positive evidence for the case of luxury brand labels. However, an issue of this study was that some of the experiments were not conducted in a perfectly double-blind manner. I resolved this by replicating variations of the original design in a double-blind procedure. Additionally, besides the luxury label condition, I introduced a “green” label condition. Thus, the hypothesis that signaling theory is able to explain pro-environmental behavior was tested for the first time in a natural field setting. Further, I conducted experiments in both average and below-average socioeconomic neighborhoods, where, according to signaling theory, the effects of luxury signals should be even stronger. In contrast to the original study, I did not find positive effects of the luxury brand label in any of the five experiments. Nor did I find evidence for a green-signaling effect. Moreover, in poor neighborhoods a negative tendency of the luxury label actually became evident. This suggests that a signaling theory explanation of costly labels must take into account the characteristics of the observers, e.g. their social status.
    Keywords: Research Article ; Biology And Life Sciences ; Biology And Life Sciences ; Biology And Life Sciences ; Social Sciences ; Biology And Life Sciences ; Social Sciences ; Biology And Life Sciences ; Social Sciences ; Social Sciences ; Biology And Life Sciences ; Biology And Life Sciences ; Biology And Life Sciences ; Earth Sciences ; Social Sciences ; Biology And Life Sciences ; Biology And Life Sciences ; Biology And Life Sciences ; Social Sciences ; Biology And Life Sciences ; Social Sciences
    E-ISSN: 1932-6203
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  • 2
    In: PLoS ONE, 2015, Vol.10(4)
    Description: This paper identifies trends within and relationships between the amount of participation and the quality of contributions in three crowdsourced surveys. Participants were asked to perform a collective problem solving task that lacked any explicit incentive: they were instructed not only to respond to survey questions but also to pose new questions that they thought might-if responded to by others-predict an outcome variable of interest to them. While the three surveys had very different outcome variables, target audiences, methods of advertisement, and lengths of deployment, we found very similar patterns of collective behavior. In particular, we found that: the rate at which participants submitted new survey questions followed a heavy-tailed distribution; the distribution in the types of questions posed was similar; and many users posed non-obvious yet predictive questions. By analyzing responses to questions that contained a built-in range of valid response we found that less than 0.2% of responses lay outside of those ranges, indicating that most participants tend to respond honestly to surveys of this form, even without explicit incentives for honesty. While we did not find a significant relationship between the quantity of participation and the quality of contribution for both response submissions and question submissions, we did find several other more nuanced participant behavior patterns, which did correlate with contribution in one of the three surveys. We conclude that there exists an optimal time for users to pose questions early on in their participation, but only after they have submitted a few responses to other questions. This suggests that future crowdsourced surveys may attract more predictive questions by prompting users to pose new questions at specific times during their participation and limiting question submission at non-optimal times.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 3
    In: PLoS ONE, 2015, Vol.10(7)
    Description: Background Mortality from ischemic stroke has declined over time. However, little is known about the reasons for the decreased mortality. We therefore aimed to evaluate trends in in-hospital mortality and to identify factors associated with these trends. Methods This study was based on a prospective database of 26 hospitals of the Stroke Register of Northwestern Germany, which included 73,614 patients admitted between 2000 and 2011. Time trends in observed (crude) and risk-adjusted in-hospital mortality were assessed. Independent factors associated with death after stroke were evaluated using multivariable logistic regression analysis. Results The observed in-hospital mortality decreased from 6.6% in 2000 to 4.6% in 2008 (P 〈 0.001 for trend) and then remained fairly stable. The risk-adjusted mortality decreased from 2.85% in 2000 to 1.86% in 2008 (P 〈 0.01 for trend) and then increased to 2.32% in 2011. Use of in-hospital treatments including antiplatelets within 48 hours, antihypertensive therapy, statins, antidiabetics, physiotherapy and anticoagulants increased over time and was significantly associated with a decrease in mortality. The association of the year of admission with mortality became insignificant after adjustment for antiplatelet therapy within 48 hours (from OR 0.96; 95% CI, 0.94-0.98, to OR 0.99; 95% CI, 0.97-1.01) and physiotherapy (from OR 0.96; 95% CI, 0.94-0.97, to OR 0.99; 95% CI, 0.97-1.00). Conclusions In-hospital mortality decreased by approximately one third between 2000 and 2008. This decline was paralleled by improvements in different in-hospital managements, and we demonstrated that it was partly mediated by early antiplatelet therapy and physiotherapy use.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 4
    In: PLoS ONE, 2015, Vol.10(5)
    Description: Microvesicles are of increasing interest in biology as part of normal function of numerous systems; from the immune system (T cell activation) to implantation of the embryo (invasion of the trophoblasts) and sperm maturation (protein transfer in the epididymis). Yet, the mechanisms involved in the appearance of apical blebbing from healthy cells as part of their normal function remain understudied. Microvesicles are produced via one of two pathways: exocytosis or apical blebbing also termed ectocytosis. This work quantifies the histological appearance of apical blebbing in the porcine epididymis during development and examines the role of endogenous estrogens in regulating this blebbing. Apical blebbing appears at puberty and increases in a linear manner into sexual maturity suggesting that this blebbing is a mature phenotype. Endogenous estrogen levels were reduced with an aromatase inhibitor but such a reduction did not affect apical blebbing in treated animals compared with their vehicle-treated littermates. Epididymal production of apical blebs is a secretion mechanism of functionally mature principal cells regulated by factors other than estradiol.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 5
    In: PLoS ONE, 2016, Vol.11(1)
    Description: We present the software library marathon , which is designed to support the analysis of sampling algorithms that are based on the Markov-Chain Monte Carlo principle. The main application of this library is the computation of properties of so-called state graphs, which represent the structure of Markov chains. We demonstrate applications and the usefulness of marathon by investigating the quality of several bounding methods on four well-known Markov chains for sampling perfect matchings and bipartite graphs. In a set of experiments, we compute the total mixing time and several of its bounds for a large number of input instances. We find that the upper bound gained by the famous canonical path method is often several magnitudes larger than the total mixing time and deteriorates with growing input size. In contrast, the spectral bound is found to be a precise approximation of the total mixing time.
    Keywords: Research Article ; Computer And Information Sciences ; Physical Sciences ; Physical Sciences ; Research And Analysis Methods ; Physical Sciences ; Physical Sciences ; Computer And Information Sciences ; Physical Sciences ; Research And Analysis Methods
    E-ISSN: 1932-6203
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  • 6
    In: PLoS ONE, 2013, Vol.8(10)
    Description: The maturation of an oocyte into an egg is a key step in preparation for fertilization. In Xenopus , oocyte maturation is independent of transcription, being regulated at the level of translation and post-translational modifications of proteins. To identify factors involved in the maturation process we used two-dimensional differential gel electrophoresis to compare the proteome of oocytes and eggs. Protein abundance changes were observed in multiple cellular pathways during oocyte maturation. Most prominent was a general reduction in abundance of enzymes in the glycolytic pathway. Injection into oocytes of the glycolytic intermediates glyceraldehyde-3-phosphate, phosphoenolpyruvate and glucose-6-phosphate prevented oocyte maturation. Instead, these metabolites stimulated ROS production and subsequent apoptosis of the oocyte. In contrast, all other metabolites tested had no effect on oocyte maturation and did not induce apoptosis. These data suggest that a subset of glycolytic metabolites have the capacity to regulate oocyte viability.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 7
    Language: English
    In: PLoS ONE, 01 January 2014, Vol.9(7), p.e100950
    Description: Erufosine is a new antineoplastic agent of the group of alkylphosphocholines, which interferes with signal transduction and induces apoptosis in various leukemic and tumor cell lines. The present study was designed to examine for the first time the mechanism of resistance to erufosine in malignant cells with permanently reduced expression of the retinoblastoma (Rb) protein. Bearing in mind the high number of malignancies with reduced level of this tumor-suppressor, this investigation was deemed important for using erufosine, alone or in combination, in patients with compromised RB1 gene expression. For this purpose, clones of the leukemic T-cell line SKW-3 were used, which had been engineered to constantly express differently low Rb levels. The alkylphosphocholine induced apoptosis, stimulated the expression of the cyclin dependent kinase inhibitor p27Kip1 and inhibited the synthesis of cyclin D3, thereby causing a G2 phase cell cycle arrest and death of cells with wild type Rb expression. In contrast, Rb-deficiency impeded the changes induced by erufosine in the expression of these proteins and abrogated the induction of G2 arrest, which was correlated with reduced antiproliferative and anticlonogenic activities of the compound. In conclusion, analysis of our results showed for the first time that the Rb signaling pathway is essential for mediating the antineoplastic activity of erufosine and its efficacy in patients with malignant diseases may be predicted by determining the Rb status.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 8
    Language: English
    In: PLoS ONE, 2011, Vol.6(10), p.e25858
    Description: Type I interferons (IFN) comprise a family of cytokines that signal through a common cellular receptor to induce a plethora of genes with antiviral and other activities. Recombinant IFNs are used for the treatment of hepatitis C virus infection, multiple sclerosis, and certain malignancies. The capability of type I IFN to suppress virus replication and resultant cytopathic effects is frequently used to measure their bioactivity. However, these assays are time-consuming and require appropriate biosafety containment. In this study, an improved IFN assay is presented which is based on a recombinant vesicular stomatitis virus (VSV) replicon encoding two reporter proteins, firefly luciferase and green fluorescent protein. The vector lacks the essential envelope glycoprotein (G) gene of VSV and is propagated on a G protein-expressing transgenic cell line. Several mammalian and avian cells turned out to be susceptible to infection with the complemented replicon particles. Infected cells readily expressed the reporter proteins at high levels five hours post infection. When human fibroblasts were treated with serial dilutions of human IFN-β prior to infection, reporter expression was accordingly suppressed. This method was more sensitive and faster than a classical IFN bioassay based on VSV cytopathic effects. In addition, the antiviral activity of human IFN-λ (interleukin-29), a type III IFN, was determined on Calu-3 cells. Both IFN-β and IFN-λ were acid-stable, but only IFN-β was resistant to alkaline treatment. The antiviral activities of canine, porcine, and avian type I IFN were analysed with cell lines derived from the corresponding species. This safe bioassay will be useful for the rapid and sensitive quantification of multi-species type I IFN and potentially other antiviral cytokines.
    Keywords: Research Article ; Biology ; Medicine ; Veterinary Science ; Immunology ; Virology ; Infectious Diseases ; Microbiology ; Molecular Biology
    E-ISSN: 1932-6203
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  • 9
    Language: English
    In: PLoS ONE, 2012, Vol.7(4), p.e34578
    Description: According to optimal foraging theory, foraging decisions are based on the forager's current estimate of the quality of its environment. However, in a novel environment, a forager does not possess information regarding the quality of the environment, and may make a decision based on a biased estimate. We show, using a simple simulation model, that when facing uncertainty in heterogeneous environments it is better to overestimate the quality of the environment (to be an “optimist”) than underestimate it, as optimistic animals learn the true value of the environment faster due to higher exploration rate. Moreover, we show that when the animal has the capacity to remember the location and quality of resource patches, having a positively biased estimate of the environment leads to higher fitness gains than having an unbiased estimate, due to the benefits of exploration. Our study demonstrates how a simple model of foraging with incomplete information, derived directly from optimal foraging theory, can produce well documented complex space-use patterns of exploring animals.
    Keywords: Research Article ; Biology ; Computational Biology ; Ecology ; Neuroscience ; Evolutionary Biology
    E-ISSN: 1932-6203
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  • 10
    Language: English
    In: PLoS ONE, 23 March 2015, Vol.10(3), p.e0120821
    Description: Cranial nerves govern sensory and motor information exchange between the brain and tissues of the head and neck. The cranial nerves are derived from two specialized populations of cells, cranial neural crest cells and ectodermal placode...
    Keywords: Life Sciences ; Human Health and Pathology ; Sciences (General)
    ISSN: 1932-6203
    E-ISSN: 1932-6203
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