166 research outputs found

    Inverse spectral problems for energy-dependent Sturm-Liouville equations

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    We study the inverse spectral problem of reconstructing energy-dependent Sturm-Liouville equations from their Dirichlet spectra and sequences of the norming constants. For the class of problems under consideration, we give a complete description of the corresponding spectral data, suggest a reconstruction algorithm, and establish uniqueness of reconstruction. The approach is based on connection between spectral problems for energy-dependent Sturm-Liouville equations and for Dirac operators of special form.Comment: AMS-LaTeX, 28 page

    Social Interactions vs Revisions, What is important for Promotion in Wikipedia?

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    In epistemic community, people are said to be selected on their knowledge contribution to the project (articles, codes, etc.) However, the socialization process is an important factor for inclusion, sustainability as a contributor, and promotion. Finally, what does matter to be promoted? being a good contributor? being a good animator? knowing the boss? We explore this question looking at the process of election for administrator in the English Wikipedia community. We modeled the candidates according to their revisions and/or social attributes. These attributes are used to construct a predictive model of promotion success, based on the candidates's past behavior, computed thanks to a random forest algorithm. Our model combining knowledge contribution variables and social networking variables successfully explain 78% of the results which is better than the former models. It also helps to refine the criterion for election. If the number of knowledge contributions is the most important element, social interactions come close second to explain the election. But being connected with the future peers (the admins) can make the difference between success and failure, making this epistemic community a very social community too

    Using Games to Create Language Resources: Successes and Limitations of the Approach

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    Abstract One of the more novel approaches to collaboratively creating language resources in recent years is to use online games to collect and validate data. The most significant challenges collaborative systems face are how to train users with the necessary expertise and how to encourage participation on a scale required to produce high quality data comparable with data produced by “traditional ” experts. In this chapter we provide a brief overview of collaborative creation and the different approaches that have been used to create language resources, before analysing games used for this purpose. We discuss some key issues in using a gaming approach, including task design, player motivation and data quality, and compare the costs of each approach in terms of development, distribution and ongoing administration. In conclusion, we summarise the benefits and limitations of using a gaming approach to resource creation and suggest key considerations for evaluating its utility in different research scenarios

    Multiplicities of charged pions and unidentified charged hadrons from deep-inelastic scattering of muons off an isoscalar target

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    Multiplicities of charged pions and unidentified hadrons produced in deep-inelastic scattering were measured in bins of the Bjorken scaling variable xx, the relative virtual-photon energy yy and the relative hadron energy zz. Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam and an isoscalar target (6^6LiD). They cover the kinematic domain in the photon virtuality Q2Q^2 > 1(GeV/c)2)^2, 0.004<x<0.40.004 < x < 0.4, 0.2<z<0.850.2 < z < 0.85 and 0.1<y<0.70.1 < y < 0.7. In addition, a leading-order pQCD analysis was performed using the pion multiplicity results to extract quark fragmentation functions

    Prokineticin 1 induces Dickkopf 1 expression and regulates cell proliferation and decidualization in the human endometrium

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    Prokineticin 1 (PROK1) signalling via prokineticin receptor 1 (PROKR1) regulates the expression of several genes with important roles in endometrial receptivity and implantation. This study investigated PROK1 regulation of Dickkopf 1 (DKK1) expression, a negative regulator of canonical Wnt signalling, and its function in the non-pregnant endometrium and first trimester decidua. DKK1 mRNA expression is elevated during the mid-secretory phase of the menstrual cycle and expression increases further in first trimester decidua. DKK1 protein expression is localized to glandular epithelial and stromal cells during the proliferative, early- and mid-secretory phases, whereas expression is confined to the stroma in the late-secretory phase and first trimester decidua. PROK1 induces the expression of DKK1 in endometrial epithelial cells stably expressing PROKR1 and in first trimester decidua explants, via a Gq-calcium-calcineurin-nuclear factor of activated T-cells-mediated pathway. Endometrial epithelial cell proliferation is negatively regulated by PROK1-PROKR1 signalling. We demonstrate that this effect on cell proliferation occurs via DKK1 expression, as siRNA targeted against DKK1 reduces the PROK1-induced decrease in proliferation. Furthermore, decidualization of primary human endometrial stromal cells with progesterone and cyclic adenosine monophosphate is inhibited by miRNA knock down of PROK1 or DKK1. These data demonstrate important roles for PROK1 and DKK1 during endometrial receptivity and early pregnancy, which include regulation of endometrial cell proliferation and decidualization

    Mapping subnational HIV mortality in six Latin American countries with incomplete vital registration systems

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    Background: Human immunodeficiency virus (HIV) remains a public health priority in Latin America. While the burden of HIV is historically concentrated in urban areas and high-risk groups, subnational estimates that cover multiple countries and years are missing. This paucity is partially due to incomplete vital registration (VR) systems and statistical challenges related to estimating mortality rates in areas with low numbers of HIV deaths. In this analysis, we address this gap and provide novel estimates of the HIV mortality rate and the number of HIV deaths by age group, sex, and municipality in Brazil, Colombia, Costa Rica, Ecuador, Guatemala, and Mexico. Methods: We performed an ecological study using VR data ranging from 2000 to 2017, dependent on individual country data availability. We modeled HIV mortality using a Bayesian spatially explicit mixed-effects regression model that incorporates prior information on VR completeness. We calibrated our results to the Global Burden of Disease Study 2017. Results: All countries displayed over a 40-fold difference in HIV mortality between municipalities with the highest and lowest age-standardized HIV mortality rate in the last year of study for men, and over a 20-fold difference for women. Despite decreases in national HIV mortality in all countries—apart from Ecuador—across the period of study, we found broad variation in relative changes in HIV mortality at the municipality level and increasing relative inequality over time in all countries. In all six countries included in this analysis, 50% or more HIV deaths were concentrated in fewer than 10% of municipalities in the latest year of study. In addition, national age patterns reflected shifts in mortality to older age groups—the median age group among decedents ranged from 30 to 45 years of age at the municipality level in Brazil, Colombia, and Mexico in 2017. Conclusions: Our subnational estimates of HIV mortality revealed significant spatial variation and diverging local trends in HIV mortality over time and by age. This analysis provides a framework for incorporating data and uncertainty from incomplete VR systems and can help guide more geographically precise public health intervention to support HIV-related care and reduce HIV-related deaths

    Characterisation of the dip-bump structure observed in proton-proton elastic scattering at root s=8 TeV

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    The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton-proton scattering at root s = 8 TeV in the squared four-momentum transfer range 0.2 GeV2 &lt; vertical bar t vertical bar &lt; 1.9 GeV2. This interval includes the structure with a diffractive minimum ("dip") and a secondary maximum ("bump") that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for root s = 8 TeV yields the positions, vertical bar t vertical bar(dip) = (0.521 +/- 0.007) GeV2 and vertical bar t vertical bar(bump) = (0.695 +/- 0.026) GeV2, as well as the cross-section values, d sigma/dt vertical bar(dip) = (15.1 +/- 2.5) mu b/GeV2 and d sigma/dt vertical bar(bump) = (29.7 +/- 1.8) mu b/Ge-2, for the dip and the bump, respectively

    The motivation for citizens’ involvement in life sciences research is predicted by age and gender

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    Open Science is an umbrella term encompassing multiple concepts as open access to publications, open data, open education and citizen science that aim to make science more open and transparent. Citizen science, an important facet of Open Science, actively involves nonscientists in the research process, and can potentially be beneficial for multiple actors, such as scientists, citizens, policymakers and society in general. However, the reasons that motivate different segments of the public to participate in research are still understudied. Therefore, based on data gathered from a survey conducted in Czechia, Germany, Italy, Spain, Sweden, and the UK (N = 5,870), this study explores five types of incentives that can motivate individuals to become involved in life sciences research. The results demonstrate that men and younger individuals are more persuaded by extrinsic motives (external benefits or rewards), as compared with women and older people, who are driven by intrinsic motives (that originates from within an individual). This paper shows that specific strata of the population are differentially motivated to engage in research, thereby providing relevant knowledge for effectively designing public involvement activities that target various groups of the public in research projects

    Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target

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    Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar 6LiD target. They cover the kinematic domain View the MathML source in the photon virtuality, 0.0045 GeV/c2 in the invariant mass of the hadronic system. The results from the sum of the z -integrated K+ and K 12 multiplicities at high x point to a value of the non-strange quark fragmentation function larger than obtained by the earlier DSS fit

    Triangle Singularity as the Origin of the a1(1420)

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    The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a(1)(1420), decaying to f(0)(980)(pi). With a mass too close to and a width smaller than the axial-vector ground state a(1)(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a(1) (1260) resonance into K* (-> K pi) (K) over bar and subsequent rescattering through a triangle singularity into the coupled f(0)(980)p channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the lightmeson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect
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