127 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

    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

    Tag-Aware Recommender Systems: A State-of-the-art Survey

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    In the past decade, Social Tagging Systems have attracted increasing attention from both physical and computer science communities. Besides the underlying structure and dynamics of tagging systems, many efforts have been addressed to unify tagging information to reveal user behaviors and preferences, extract the latent semantic relations among items, make recommendations, and so on. Specifically, this article summarizes recent progress about tag-aware recommender systems, emphasizing on the contributions from three mainstream perspectives and approaches: network-based methods, tensor-based methods, and the topic-based methods. Finally, we outline some other tag-related works and future challenges of tag-aware recommendation algorithms.Comment: 19 pages, 3 figure

    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

    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

    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

    Interleukin-1 beta has atheroprotective effects in advanced atherosclerotic lesions of mice

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    Despite decades of research, our understanding of the processes controlling late-stage atherosclerotic plaque stability remains poor. A prevailing hypothesis is that reducing inflammation may improve advanced plaque stability, as recently tested in the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) trial, in which post-myocardial infarction subjects were treated with an IL-1β antibody. Here, we performed intervention studies in which smooth muscle cell (SMC) lineage-tracing Apoe-/- mice with advanced atherosclerosis were treated with anti-IL-1β or IgG control antibodies. Surprisingly, we found that IL-1β antibody treatment between 18 and 26 weeks of Western diet feeding induced a marked reduction in SMC and collagen content, but increased macrophage numbers in the fibrous cap. Moreover, although IL-1β antibody treatment had no effect on lesion size, it completely inhibited beneficial outward remodeling. We also found that SMC-specific knockout of Il1r1 (encoding IL-1 receptor type 1) resulted in smaller lesions nearly devoid of SMCs and lacking a fibrous cap, whereas macrophage-selective loss of IL-1R1 had no effect on lesion size or composition. Taken together, these results show that IL-1β has multiple beneficial effects in late-stage murine atherosclerosis, including promotion of outward remodeling and formation and maintenance of an SMC- and collagen-rich fibrous cap

    The Emergence and Global Spread of Noninvasive Prenatal Testing

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    Since its introduction in 2011, noninvasive prenatal testing (NIPT) has spread rapidly around the world. It carries numerous benefits but also raises challenges, often related to sociocultural, legal, and economic contexts. This article describes the implementation of NIPT in nine countries, each with its own unique characteristics: Australia, Canada, China and Hong Kong, India, Israel, Lebanon, the Netherlands, the United Kingdom, and the United States. Themes covered for each country include the structure of the healthcare system, how NIPT is offered, counseling needs and resources, and cultural and legal context regarding disability and pregnancy termination. Some common issues emerge, including cost as a barrier to equitable access, the complexity of decision-making about public funding, and a shortage of appropriate resources that promote informed choice. Conversely, sociocultural values that underlie the use of NIPT vary greatly among countries. The issues described will become even more challenging as NIPT evolves from a second-tier to a first-tier screening test with expanded use. Expected final online publication date for the Annual Review of Genomics and Human Genetics Volume 22 is August 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates
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