751 research outputs found

    Compact pseudo-Riemannian manifolds with parallel Weyl tensor

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    It is shown that in every dimension n=3j+2, j=1,2,3,..., there exist compact pseudo-Riemannian manifolds with parallel Weyl tensor, which are Ricci-recurrent, but neither conformally flat nor locally symmetric, and represent all indefinite metric signatures. The manifolds in question are diffeomorphic to nontrivial torus bundles over the circle. They all arise from a construction that a priori yields bundles over the circle, having as the fibre either a torus, or a 2-step nilmanifold with a complete flat torsionfree connection; our argument only realizes the torus case.Comment: 19 page

    Inherent biomechanical traits enable infective filariae to disseminate through collecting lymphatic vessels

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    Filariases are diseases caused by arthropod-borne filaria nematodes. The related pathologies depend on the location of the infective larvae when their migration, the asymptomatic and least studied phase of the disease, comes to an end. To determine factors assisting in filariae dissemination, we image Litomosoides sigmodontis infective larvae during their escape from the skin. Burrowing through the dermis filariae exclusively enter pre-collecting lymphatics by mechanical disruption of their wall. Once inside collectors, their rapid and unidirectional movement towards the lymph node is supported by the morphology of lymphatic valves. In a microfluidic maze mimicking lymphatic vessels, filariae follow the direction of the flow, the first biomechanical factor capable of helminth guidance within the host. Finally, non-infective nematodes that rely on universal morpho-physiological cues alone also migrate through the dermis, and break in lymphatics, indicating that the ability to spread by the lymphatic route is an ancestral trait rather than acquired parasitic adaptation

    The orthogonal-oblique bi-level model of the Outcome Questionnaire (OQ-45.2) : the case of the Polish factorial normalization

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    Aim. The aim of this project was to conduct the cross-cultural factorial validation of the Outcome Questionnaire (OQ-45.2) using the Polish population. Material and method. Data were obtained from day-patients (n = 211), inpatients (n = 234), outpatients (n = 137) and non-patients (n = 426). Statistical analyses included: parallel analysis, exploratory factor analysis, confirmatory factor analysis, correlation analysis, criterion equivalence, clinical significance and reliable change index, and test-retest. Results. Statistical analyses provided the strongest support for the bi-level model of the total score, five orthogonal (subscales specific for the Polish OQ, i.e. Social Conflicts and Addictive Behaviors; and original yet modified subscales, i.e. Symptom Distress, Interpersonal Relations, and Social Role), and two oblique factors (Somatization and Anxiety, Social Role 2). The psychometric properties of the Polish OQ were found to be adequate and similar to the original American OQ and its international adaptations. Specific for the Polish OQ cutoff scores for clinical significance were established. The role of cultural differences and the passage of time in the process of the cross-cultural validation were elaborated upon. Conclusions. The Polish version of the OQ 45-2 has been recognized as an instrument adequately measuring general functioning as well as specific areas of functioning of the individual (i.e. interpersonal relations; social role performance; social conflicts; symptom distress; somatization and anxiety; addictive behaviors). Results of this factorial analysis seem to be valuable for both clinicians using the OQ-45.2 and for creators of any psychotherapy outcome measure

    Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES

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    We present measurements of exclusive ensuremathπ+,0 and η production in pp reactions at 1.25GeV and 2.2GeV beam kinetic energy in hadron and dielectron channels. In the case of π+ and π0 , high-statistics invariant-mass and angular distributions are obtained within the HADES acceptance as well as acceptance-corrected distributions, which are compared to a resonance model. The sensitivity of the data to the yield and production angular distribution of Δ (1232) and higher-lying baryon resonances is shown, and an improved parameterization is proposed. The extracted cross-sections are of special interest in the case of pp → pp η , since controversial data exist at 2.0GeV; we find \ensuremathσ=0.142±0.022 mb. Using the dielectron channels, the π0 and η Dalitz decay signals are reconstructed with yields fully consistent with the hadronic channels. The electron invariant masses and acceptance-corrected helicity angle distributions are found in good agreement with model predictions

    Structural trends in atomic nuclei from laser spectroscopy of tin

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    Tin is the chemical element with the largest number of stable isotopes. Its complete proton shell, comparable with the closed electron shells in the chemically inert noble gases, is not a mere precursor to extended stability; since the protons carry the nuclear charge, their spatial arrangement also drives the nuclear electromagnetism. We report high-precision measurements of the electromagnetic moments and isomeric differences in charge radii between the lowest 1/2(+), 3/2(+), and 11/2(-) states in Sn117-131, obtained by collinear laser spectroscopy. Supported by state-of-the-art atomic-structure calculations, the data accurately show a considerable attenuation of the quadrupole moments in the closed-shell tin isotopes relative to those of cadmium, with two protons less. Linear and quadratic mass-dependent trends are observed. While microscopic density functional theory explains the global behaviour of the measured quantities, interpretation of the local patterns demands higher-fidelity modelling. Measurements of the hyperfine structure of chemical elements isotopes provide unique insight into the atomic nucleus in a nuclear model-independent way. The authors present collinear laser spectroscopy data obtained at the CERN ISOLDE and measure hyperfine splitting along a long chain of odd-mass tin isotopes.Peer reviewe

    Galaxy and Mass Assembly (GAMA): Variation in galaxy structure across the green valley

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    Using a sample of 472 local Universe (z \u3c 0.06) galaxies in the stellar mass range 10.25 \u3c logM*/M⊙ \u3c 10.75, we explore the variation in galaxy structure as a function of morphology and galaxy colour. Our sample of galaxies is subdivided into red, green, and blue colour groups and into elliptical and non-elliptical (disk-type) morphologies. Using Kilo- Degree Survey (KiDS) and Visible and Infrared Survey Telescope for Astronomy (VISTA) Kilo-Degree Infrared Galaxy Survey (VIKING) derived postage stamp images, a group of eight volunteers visually classified bars, rings, morphological lenses, tidal streams, shells, and signs of merger activity for all systems. We find a significant surplus of rings (2.3s) and lenses (2.9s) in disk-type galaxies as they transition across the green valley. Combined, this implies a joint ring/lens green valley surplus significance of 3.3s relative to equivalent disk-types within either the blue cloud or the red sequence. We recover a bar fraction of ~44 per cent which remains flat with colour, however, we find that the presence of a bar acts to modulate the incidence of rings and (to a lesser extent) lenses, with rings in barred disk-type galaxies more common by ~20-30 percentage points relative to their unbarred counterparts, regardless of colour. Additionally, green valley disk-type galaxies with a bar exhibit a significant 3.0s surplus of lenses relative to their blue/red analogues. The existence of such structures rules out violent transformative events as the primary end-of-life evolutionary mechanism, with a more passive scenario the favoured candidate for the majority of galaxies rapidly transitioning across the green valley

    Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context

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    Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts

    Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas

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    Although theMYConcogene has been implicated incancer, a systematic assessment of alterations ofMYC, related transcription factors, and co-regulatoryproteins, forming the proximal MYC network (PMN),across human cancers is lacking. Using computa-tional approaches, we define genomic and proteo-mic features associated with MYC and the PMNacross the 33 cancers of The Cancer Genome Atlas.Pan-cancer, 28% of all samples had at least one ofthe MYC paralogs amplified. In contrast, the MYCantagonists MGA and MNT were the most frequentlymutated or deleted members, proposing a roleas tumor suppressors.MYCalterations were mutu-ally exclusive withPIK3CA,PTEN,APC,orBRAFalterations, suggesting that MYC is a distinct onco-genic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such asimmune response and growth factor signaling; chro-matin, translation, and DNA replication/repair wereconserved pan-cancer. This analysis reveals insightsinto MYC biology and is a reference for biomarkersand therapeutics for cancers with alterations ofMYC or the PMN

    Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

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    This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin
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