2,574 research outputs found

    Distributional Modes for Scalar Field Quantization

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    We propose a mode-sum formalism for the quantization of the scalar field based on distributional modes, which are naturally associated with a slight modification of the standard plane-wave modes. We show that this formalism leads to the standard Rindler temperature result, and that these modes can be canonically defined on any Cauchy surface.Comment: 15 pages, RevTe

    Abscission couples cell division to embryonic stem cell fate

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    Cell fate transitions are key to development and homeostasis. It is thus essential to understand the cellular mechanisms controlling fate transitions. Cell division has been implicated in fate decisions in many stem cell types, including neuronal and epithelial progenitors. In other stem cells, such as embryonic stem (ES) cells, the role of division remains unclear. Here, we show that exit from naive pluripotency in mouse ES cells generally occurs after a division. We further show that exit timing is strongly correlated between sister cells, which remain connected by cytoplasmic bridges long after division, and that bridge abscission progressively accelerates as cells exit naive pluripotency. Finally, interfering with abscission impairs naive pluripotency exit, and artificially inducing abscission accelerates it. Altogether, our data indicate that a switch in the division machinery leading to faster abscission regulates pluripotency exit. Our study identifies abscission as a key cellular process coupling cell division to fate transitions

    Evaluating a scale of excessive mind wandering among males and females with and without attention-deficit/hyperactivity disorder from a population sample

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    Recent studies highlight the role of excessive mind wandering in attention-deficit/hyperactivity disorder (ADHD) and its association with impairment. We believe assessing mind wandering could be especially relevant to individuals, including many females, who present with less externalising manifestations of ADHD. Using a new measure based on ADHD patient reports, the Mind Excessively Wandering Scale (MEWS), we previously found adults with ADHD had elevated levels of mind wandering that contributed to impairment independently of core ADHD symptoms. Using data from an online general population survey, the current study assessed the factor-structure, reliability, validity and measurement invariance of the MEWS. We also investigated sex differences in mind wandering, as well as ADHD symptoms, impairment and wellbeing in those with and without ADHD. The MEWS had a unidimensional structure, was invariant across sex, age and ADHD status, and accounted for unique variance in impairment and wellbeing beyond core ADHD symptoms. Among those with ADHD, we found no evidence for sex differences in mind wandering and among those without ADHD males had higher scores. We also found similar levels of hyperactivity/impulsivity, emotional lability, and impairment in males and females with ADHD, but males reported greater inattention and lower wellbeing. Results suggest the MEWS is a reliable and valid instrument measuring the same construct across sex, age and ADHD status, which could aid diagnosis and monitoring of outcomes

    Tidal Response of Mars Constrained From Laboratory-Based Viscoelastic Dissipation Models and Geophysical Data

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    We employ laboratory-based grain-size- and temperature-sensitive rheological models to 16 describe the viscoelastic behavior of terrestrial bodies with focus on Mars. Shear modulus 17 reduction and attenuation related to viscoelastic relaxation occur as a result of diffusion- 18 and dislocation-related creep and grain-boundary processes. We consider five rheological 19 models, including extended Burgers, Andrade, Sundberg-Cooper, a power-law approxima- 20 tion, and Maxwell, and determine Martian tidal response. However, the question of which 21 model provides the most appropriate description of dissipation in planetary bodies, re- 22 mains an open issue. To examine this, crust and mantle models (density and elasticity) are 23 computed self-consistently through phase equilibrium calculations as a function of pres- 24 sure, temperature, and bulk composition, whereas core properties are based on an Fe-FeS 25 parameterisation. We assess the compatibility of the viscoelastic models by inverting the 26 available geophysical data for Mars (tidal response and mean density and moment of in- 27 ertia) for temperature, elastic, and attenuation structure. Our results show that although 28 all viscoelastic models are consistent with data, their predictions for the tidal response at 29 other periods and harmonic degrees are distinct. The results also show that Maxwell is 30 only capable of fitting data for unrealistically low viscosities. Our approach can be used 31 quantitatively to distinguish between the viscoelastic models from seismic and/or tidal ob- 32 servations that will allow for improved constraints on interior structure (e.g., with InSight). 33 Finally, the methodology presented here is generally formulated and applicable to other so- 34 lar and extra-solar system bodies where the study of tidal dissipation presents an important 35 means for determining interior structure

    Uterine Mast Cells and Immunoglobulin-E Antibody Responses During Clearance of \u3ci\u3eTritrichomonas foetus\u3c/i\u3e

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    We showed earlier that Tritrichomonas foetus–specific bovine immunoglobulin (Ig)G1 and IgA antibodies in uterine and vaginal secretions are correlated with clearance of this sexually transmitted infection. Eosinophils have been noted in previous studies of bovine trichomoniasis but the role of mast cells and IgE responses have not been reported. The hypothesis that IgE and mast cell degranulation play a role in clearance was tested in 25 virgin heifers inseminated experimentally and infected intravaginally with T. foetus strain D1 at estrus and cultured weekly. Groups were euthanatized at 3, 6, 9, or 12 weeks, when tissues were fixed and secretions were collected for culture and antibody analysis. Immunohistochemistry using a monoclonal antibody to a soluble lipophosphoglycan (LPG)–containing surface antigen (TF1.17) demonstrated antigen uptake by uterine epithelial cells. Lymphoid nodules were detected below antigen-positive epithelium. Little IgG2 antibody was detected but IgG1, IgA, IgM, and IgE T. foetus–specific antibodies increased in uterine secretions at weeks 6 and 9 after infection. This was inversely proportional to subepithelial mast cells numbers and most animals cleared the infection by the sampling time after the lowest mast cell count. Furthermore, soluble antigen was found in uterine epithelium above inductive sites (lymphoid nodules). Cross-linking of IgE on mast cells by antigen and perhaps LPG triggering appears to have resulted in degranulation. Released cytokines may account for production of predominantly Th2 (IgG1 and IgE) and IgA antibody responses, which are related to clearance of the infection

    Constraints on Models for the Higgs Boson with Exotic Spin and Parity in VH → Vb¯b Final States

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    This is the published version. Copyright © 2014 American Physical SocietyWe present constraints on models containing non-standard-model values for the spin J and parity P of the Higgs boson H in up to 9.7  fb−1 of ppÂŻ collisions at s√=1.96  TeV collected with the D0 detector at the Fermilab Tevatron Collider. These are the first studies of Higgs boson JP with fermions in the final state. In the ZH→ℓℓbbÂŻ, WH→ℓΜbbÂŻ, and ZH→ΜΜbbÂŻ final states, we compare the standard model (SM) Higgs boson prediction, JP=0+, with two alternative hypotheses, JP=0− and JP=2+. We use a likelihood ratio to quantify the degree to which our data are incompatible with non-SM JP predictions for a range of possible production rates. Assuming that the production rate in the signal models considered is equal to the SM prediction, we reject the JP=0− and JP=2+ hypotheses at the 97.6% CL and at the 99.0% CL, respectively. The expected exclusion sensitivity for a JP=0− (JP=2+) state is at the 99.86% (99.94%) CL. Under the hypothesis that our data are the result of a combination of the SM-like Higgs boson and either a JP=0− or a JP=2+ signal, we exclude a JP=0− fraction above 0.80 and a JP=2+ fraction above 0.67 at the 95% CL. The expected exclusion covers JP=0− (JP=2+) fractions above 0.54 (0.47)

    Measurement of the B0s Lifetime in the Flavor-Specific Decay Channel B0s→D−sÎŒ+ÎœX

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    This is the published version. Copyright 2015 American Physical SocietyWe present an updated measurement of the B0s lifetime using the semileptonic decays B0s→D−sÎŒ+ÎœX, with D−s→ϕπ− and ϕ→K+K− (and the charge conjugate process). This measurement uses the full Tevatron Run II sample of proton-antiproton collisions at s√=1.96  TeV, comprising an integrated luminosity of 10.4  fb−1. We find a flavor-specific lifetime τfs(B0s)=1.479±0.010(stat)±0.021(syst)  ps. This technique is also used to determine the B0 lifetime using the analogous B0→D−Ό+ÎœX decay with D−→ϕπ− and ϕ→K+K−, yielding τ(B0)=1.534±0.019(stat)±0.021(syst)  ps. Both measurements are consistent with the current world averages, and the B0s lifetime measurement is one of the most precise to date. Taking advantage of the cancellation of systematic uncertainties, we determine the lifetime ratio τfs(B0s)/τ(B0)=0.964±0.013(stat)±0.007(syst)

    Renewing Criminalized and Hegemonic Cultural Landscapes

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    The Mafia's long historical pedigree in Mezzogiorno, Southern Italy, has empowered the Mafioso as a notorious, uncontested, and hegemonic figure. The counter-cultural resistance against the mafiosi culture began to be institutionalized in the early 1990s. Today, Libera Terra is the largest civil society organization in the country that uses the lands confiscated from the Mafia as a space of cultural repertoire to realize its ideals. Deploying labor force through volunteer participation, producing biological fruits and vegetables, and providing information to the students on the fields are the principal cultural practices of this struggle. The confiscated lands make the Italian experience of anti-Mafia resistance a unique example by connecting the land with the ideals of cultural change. The sociocultural resistance of Libera Terra conveys a political message through these practices and utters that the Mafia is not invincible. This study draws the complex panorama of the Mafia and anti-Mafia movement that uses the ‘confiscated lands’ as cultural and public spaces for resistance and socio-cultural change. In doing so, this article sheds new light on the relationship between rural criminology and crime prevention policies in Southern Italy by demonstrating how community development practice of Libera Terra changes the meaning of landscape through iconographic symbolism and ethnographic performance

    Homothetic perfect fluid space-times

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    A brief summary of results on homotheties in General Relativity is given, including general information about space-times admitting an r-parameter group of homothetic transformations for r>2, as well as some specific results on perfect fluids. Attention is then focussed on inhomogeneous models, in particular on those with a homothetic group H4H_4 (acting multiply transitively) and H3H_3. A classification of all possible Lie algebra structures along with (local) coordinate expressions for the metric and homothetic vectors is then provided (irrespectively of the matter content), and some new perfect fluid solutions are given and briefly discussed.Comment: 27 pages, Latex file, Submitted to Class. Quantum Gra
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