Temporal perception deficits in schizophrenia: integration is the problem, not deployment of attentions

Patients with schizophrenia are known to have impairments in sensory processing. In order to understand the specific temporal perception deficits of schizophrenia, we investigated and determined to what extent impairments in temporal integration can be dissociated from attention deployment using Attentional Blink (AB). Our findings showed that there was no evident deficit in the deployment of attention in patients with schizophrenia. However, patients showed an increased temporal integration deficit within a hundred-millisecond timescale. The degree of such integration dysfunction was correlated with the clinical manifestations of schizophrenia. There was no difference between individuals with/without schizotypal personality disorder in temporal integration. Differently from previous studies using the AB, we did not find a significant impairment in deployment of attention in schizophrenia. Instead, we used both theoretical and empirical approaches to show that previous findings (using the suppression ratio to correct for the baseline difference) produced a systematic exaggeration of the attention deficits. Instead, we modulated the perceptual difficulty of the task to bring the baseline levels of target detection between the groups into closer alignment. We found that the integration dysfunction rather than deployment of attention is clinically relevant, and thus should be an additional focus of research in schizophrenia

Identification of a bipotent epithelial progenitor population in the adult thymus

SummaryThymic epithelial cells (TECs) are critically required for T cell development, but the cellular mechanisms that maintain adult TECs are poorly understood. Here, we show that a previously unidentified subpopulation, EpCam+UEA1−Ly-51+PLET1+MHC class IIhi, which comprises <0.5% of adult TECs, contains bipotent TEC progenitors that can efficiently generate both cortical (c) TECs and medullary (m) TECs. No other adult TEC population tested in this study contains this activity. We demonstrate persistence of PLET1+Ly-51+ TEC-derived cells for 9 months in vivo, suggesting the presence of thymic epithelial stem cells. Additionally, we identify cTEC-restricted short-term progenitor activity but fail to detect high efficiency mTEC-restricted progenitors in the adult thymus. Our data provide a phenotypically defined adult thymic epithelial progenitor/stem cell that is able to generate both cTECs and mTECs, opening avenues for improving thymus function in patients

Quantitative In Vivo Magnetic Resonance Spectroscopy Using Synthetic Signal Injection

Accurate conversion of magnetic resonance spectra to quantitative units of concentration generally requires compensation for differences in coil loading conditions, the gains of the various receiver amplifiers, and rescaling that occurs during post-processing manipulations. This can be efficiently achieved by injecting a precalibrated, artificial reference signal, or pseudo-signal into the data. We have previously demonstrated, using in vitro measurements, that robust pseudo-signal injection can be accomplished using a second coil, called the injector coil, properly designed and oriented so that it couples inductively with the receive coil used to acquire the data. In this work, we acquired nonlocalized phosphorous magnetic resonance spectroscopy measurements from resting human tibialis anterior muscles and used pseudo-signal injection to calculate the Pi, PCr, and ATP concentrations. We compared these results to parallel estimates of concentrations obtained using the more established phantom replacement method. Our results demonstrate that pseudo-signal injection using inductive coupling provides a robust calibration factor that is immune to coil loading conditions and suitable for use in human measurements. Having benefits in terms of ease of use and quantitative accuracy, this method is feasible for clinical use. The protocol we describe could be readily translated for use in patients with mitochondrial disease, where sensitive assessment of metabolite content could improve diagnosis and treatment

Production of dust by massive stars at high redshift

The large amounts of dust detected in sub-millimeter galaxies and quasars at high redshift pose a challenge to galaxy formation models and theories of cosmic dust formation. At z > 6 only stars of relatively high mass (> 3 Msun) are sufficiently short-lived to be potential stellar sources of dust. This review is devoted to identifying and quantifying the most important stellar channels of rapid dust formation. We ascertain the dust production efficiency of stars in the mass range 3-40 Msun using both observed and theoretical dust yields of evolved massive stars and supernovae (SNe) and provide analytical expressions for the dust production efficiencies in various scenarios. We also address the strong sensitivity of the total dust productivity to the initial mass function. From simple considerations, we find that, in the early Universe, high-mass (> 3 Msun) asymptotic giant branch stars can only be dominant dust producers if SNe generate <~ 3 x 10^-3 Msun of dust whereas SNe prevail if they are more efficient. We address the challenges in inferring dust masses and star-formation rates from observations of high-redshift galaxies. We conclude that significant SN dust production at high redshift is likely required to reproduce current dust mass estimates, possibly coupled with rapid dust grain growth in the interstellar medium.Comment: 72 pages, 9 figures, 5 tables; to be published in The Astronomy and Astrophysics Revie

Search for the supersymmetric partner of the top quark in pp̅ collisions at √s=1.96 TeV

17 pages, 11 figures. Published in Phys.Rev.D82:092001,2010.We present a search for the lightest supersymmetric partner of the top quark in proton-antiproton collisions at a center-of-mass energy √s=1.96  TeV. This search was conducted within the framework of the R parity conserving minimal supersymmetric extension of the standard model, assuming the stop decays dominantly to a lepton, a sneutrino, and a bottom quark. We searched for events with two oppositely-charged leptons, at least one jet, and missing transverse energy in a data sample corresponding to an integrated luminosity of 1  fb-1 collected by the Collider Detector at Fermilab experiment. No significant evidence of a stop quark signal was found. Exclusion limits at 95% confidence level in the stop quark versus sneutrino mass plane are set. Stop quark masses up to 180  GeV/c2 are excluded for sneutrino masses around 45  GeV/c2, and sneutrino masses up to 116  GeV/c2 are excluded for stop quark masses around 150  GeV/c2.Peer reviewe

Search for the Rare Radiative Decay: W→πγW\rightarrow\pi\gamma in \ppbar\ Collisions at s=1.96\sqrt{s} = 1.96 TeV

We present a search for the rare radiative decay \wpigamma\ using data corresponding to an integrated luminosity of 4.3 \invfb\ of proton-antiproton collisions at a center of mass energy of 1.96 TeV collected by the CDF experiment at Fermilab. As no statistically significant signal is observed, we set a 95% confidence level upper limit on the relative branching fraction \bratio\ at $6.4\times 10^{-5}$, a factor of 10 improvement over the previous limit

Search for New T′T^\prime Particles in Final States with Large Jet Multiplicities and Missing Transverse Energy in ppbar Collisions at sqrt(s) = 1.96 TeV

We present a search for a new particle T' decaying to a top quark via T' -> t + X, where X goes undetected. We use a data sample corresponding to 5.7 fb-1 of integrated luminosity of ppbar collisions with sqrt{s} = 1.96 TeV, collected at Fermilab by the CDF II detector. Our search for pair production of T' is focused on the hadronic decay channel, ppbar -> T'T' -> tt +XX -> bbqqqq + XX. We interpret our results in terms of a model where T' is an exotic fourth generation quark and X is a dark matter candidate. The data are consistent with standard model expectations. We set a limit on the generic production of T'T'->tt+XX, excluding the fourth generation exotic quarks T' at 95% confidence level up to m_T' = 400 GeV/c2 for m_X < 70 GeV/c2

Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events from ppˉp\bar{p} Collisions at s\sqrt{s} = 1.96 TeV

Accepted to Phys. Rev. LettWe present the results of a search for pair production of the supersymmetric partner of the top quark (the stop quark $\tilde{t}_{1}$) decaying to a $b$-quark and a chargino \chargino with a subsequent \chargino decay into a neutralino \neutralino, lepton $\ell$, and neutrino $\nu$. Using a data sample corresponding to 2.7 fb$^{-1}$ of integrated luminosity of $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV collected by the CDF II detector, we reconstruct the mass of candidate stop events and fit the observed mass spectrum to a combination of standard model processes and stop quark signal. We find no evidence for \pairstop production and set 95% C.L. limits on the masses of the stop quark and the neutralino for several values of the chargino mass and the branching ratio {\cal B}(\chargino\to\neutralino\ell^{\pm}\nu).We present the results of a search for pair production of the supersymmetric partner of the top quark (the top squark t˜1) decaying to a b quark and a chargino χ˜1± with a subsequent χ˜1± decay into a neutralino χ˜10, lepton ℓ, and neutrino ν. Using a data sample corresponding to 2.7  fb-1 of integrated luminosity of pp̅ collisions at √s=1.96  TeV collected by the CDF II detector, we reconstruct the mass of top squark candidate events and fit the observed mass spectrum to a combination of standard model processes and t˜1t˜̅ 1 signal. We find no evidence for t˜1t˜̅ 1 production and set 95% C.L. limits on the masses of the top squark and the neutralino for several values of the chargino mass and the branching ratio B(χ˜1±→χ˜10ℓ±ν).Peer reviewe

Search for Gluino-Mediated Sbottom Production in p-pbar Collisions at sqrt(s)=1.96 TeV

Final version publish in PRLWe report on a search for the supersymmetric partner of the bottom quark produced from gluino decays in data from 2.5 fb-1 of integrated luminosity collected by the Collider Detector at Fermilab at sqrt(s)=1.96 TeV. Candidate events are selected requiring two or more jets and large missing transverse energy. At least two of the jets are required to be tagged as originating from a b quark to enhance the sensitivity. The results are in good agreement with the prediction of the standard model processes, giving no evidence for gluino decay to sbottom quarks. This result constrains the gluino-pair-production cross section to be less than 40fb at 95% credibility level for a gluino mass of 350 GeV.We report on a search for the supersymmetric partner of the bottom quark produced from gluino decays in data from 2.5  fb-1 of integrated luminosity collected by the Collider Detector at Fermilab at √s=1.96  TeV. Candidate events are selected requiring two or more jets and large missing transverse energy. At least two of the jets are required to be tagged as originating from a b quark to enhance the sensitivity. The results are in good agreement with the prediction of the standard model processes, giving no evidence for gluino decay to bottom squarks. This result constrains the gluino-pair-production cross section to be less than 40 fb at 95% credibility level for a gluino mass of 350  GeV/c2.Peer reviewe

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements