940 research outputs found

    Model Checking Tap Withdrawal in C. Elegans

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    We present what we believe to be the first formal verification of a biologically realistic (nonlinear ODE) model of a neural circuit in a multicellular organism: Tap Withdrawal (TW) in \emph{C. Elegans}, the common roundworm. TW is a reflexive behavior exhibited by \emph{C. Elegans} in response to vibrating the surface on which it is moving; the neural circuit underlying this response is the subject of this investigation. Specifically, we perform reachability analysis on the TW circuit model of Wicks et al. (1996), which enables us to estimate key circuit parameters. Underlying our approach is the use of Fan and Mitra's recently developed technique for automatically computing local discrepancy (convergence and divergence rates) of general nonlinear systems. We show that the results we obtain are in agreement with the experimental results of Wicks et al. (1995). As opposed to the fixed parameters found in most biological models, which can only produce the predominant behavior, our techniques characterize ranges of parameters that produce (and do not produce) all three observed behaviors: reversal of movement, acceleration, and lack of response

    Suppression of field-induced spin density wave order in Sr_{3}Ru_{2}O_{7} with pressure

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    Measuring the resistivity of high-purity single crystals of Sr_{3}Ru_{2}O_{7} under pressure, we find strong evidence that the field-induced spin density wave phase at the H ∥ c metamagnetic transition is suppressed at a surprisingly low pressure of ∼ 3 ± 1 kbar. This offers the possibility of studying a bare quasi-two-dimensional spin density wave quantum critical point, testing the T → 0 K limit of theories of Planckian dissipation and quantum criticality. Preliminary attempts to fit ρ(T) with a quantum critical spin fluctuation model, while encouraging, reveal a need for further, complementary measurements

    A sensorised surgical glove to improve training and detection of obstetric anal sphincter injury: A preclinical study on a pig model

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    OBJECTIVE: To create a sensorised surgical glove that can accurately identify obstetric anal sphincter injury to facilitate timely repair, reduce complications and aid training. DESIGN: Proof-of-concept. SETTING: Laboratory. SAMPLE: Pig models. METHODS: Flexible triboelectric pressure/force sensors were mounted onto the fingertips of a routine surgical glove. The sensors produce a current when rubbed on materials of different characteristics which can be analysed. A per rectum examination was performed on the intact sphincter of pig cadavers, analogous to routine examination for obstetric anal sphincter injuries postpartum. An anal sphincter defect was created by cutting through the vaginal mucosa and into the external anal sphincter using a scalpel. The sphincter was then re-examined. Data and signals were interpreted. MAIN OUTCOME MEASURES: Sensitivity and specificity of the glove in detecting anal sphincter injury. RESULTS: In all, 200 examinations were performed. The sensors detected anal sphincter injuries in a pig model with sensitivities between 98% and 100% and a specificity of 100%. The current produced when examining an intact sphincter and sphincter with a defect was significantly different (p < 0.001). CONCLUSION: In this preliminary study, the sensorised glove accurately detected anal sphincter injury in a pig model. Future plans include its clinical translation, starting with an in-human study on postpartum women, to determine whether it can accurately detect different types of obstetric anal sphincter injury in vivo

    Kaizen newspaper

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    Systems, computer program products, and methods are disclosed for tracking an improvement event. An embodiment includes an event interface configured to receive a plurality of entries related to each of a plurality of improvement events. The plurality of entries includes a project identifier for the improvement event, a creation date, an objective, an action related to reaching the objective, and a first deadline related to the improvement event. A database interface is configured to store the plurality of entries in an event database

    Monetary policy uncertainty spillovers in time and frequency domains

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    We use the recently created monthly Interest Rate Uncertainty measure, to investigate monetary policy uncertainty across the US, Germany, France, Italy, Spain, UK, Japan, Canada, and Sweden in both the time and frequency domains. We find that the largest spillover indices are from innovations in the country itself; however, there are some instances where spillover indices between countries are large. These relationships change over time and we observe large variances in pairwise spillovers during the global financial crisis. We find that most of the volatility is confined to the crisis period. Policy makers should consider accounting for the spillovers from the US, Germany, France and Spain, as we found that they are the most consistent net transmitters of monetary policy uncertainty

    Measurement of the Dipion Mass Spectrum in X(3872) -> J/Psi Pi+ Pi- Decays

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    We measure the dipion mass spectrum in X(3872)--> J/Psi Pi+ Pi- decays using 360 pb-1 of pbar-p collisions at 1.96 TeV collected with the CDF II detector. The spectrum is fit with predictions for odd C-parity (3S1, 1P1, and 3DJ) charmonia decaying to J/Psi Pi+ Pi-, as well as even C-parity states in which the pions are from Rho0 decay. The latter case also encompasses exotic interpretations, such as a D0-D*0Bar molecule. Only the 3S1 and J/Psi Rho hypotheses are compatible with our data. Since 3S1 is untenable on other grounds, decay via J/Psi Rho is favored, which implies C=+1 for the X(3872). Models for different J/Psi-Rho angular momenta L are considered. Flexibility in the models, especially the introduction of Rho-Omega interference, enable good descriptions of our data for both L=0 and 1.Comment: 7 pages, 4 figures -- Submitted to Phys. Rev. Let

    Search for Higgs Boson Decaying to b-bbar and Produced in Association with W Bosons in p-pbar Collisions at sqrt{s}=1.96 TeV

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    We present a search for Higgs bosons decaying into b-bbar and produced in association with W bosons in p-pbar collisions at sqrt{s}=1.96 TeV. This search uses 320 pb-1 of the dataset accumulated by the upgraded Collider Detector at Fermilab. Events are selected that have a high-transverse momentum electron or muon, missing transverse energy, and two jets, one of which is consistent with a hadronization of a b quark. Both the number of events and the dijet mass distribution are consistent with standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson or any new particle with similar decay kinematics. These upper limits range from 10 pb for mH=110 GeV/c2 to 3 pb for mH=150 GeV/c2.Comment: 7 pages, 3 figures; updated title to published versio

    Search for Second-Generation Scalar Leptoquarks in ppˉ\bm{p \bar{p}} Collisions at s\sqrt{s}=1.96 TeV

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    Results on a search for pair production of second generation scalar leptoquark in ppˉp \bar{p} collisions at s\sqrt{s}=1.96 TeV are reported. The data analyzed were collected by the CDF detector during the 2002-2003 Tevatron Run II and correspond to an integrated luminosity of 198 pb1^{-1}. Leptoquarks (LQ) are sought through their decay into (charged) leptons and quarks, with final state signatures represented by two muons and jets and one muon, large transverse missing energy and jets. We observe no evidence for LQLQ production and derive 95% C.L. upper limits on the LQLQ production cross sections as well as lower limits on their mass as a function of β\beta, where β\beta is the branching fraction for LQμqLQ \to \mu q.Comment: 9 pages (3 author list) 5 figure

    Search for anomalous semileptonic decay of heavy flavor hadrons produced in association with a W boson at CDF II

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    We present a search for anomalous semileptonic decays of heavy flavor hadrons produced in association with a WW boson, in proton-antiproton collisions at sqrt{s}=1.96 TeV. We use 162 pb-1 of data collected with the CDF II detector at the Fermilab Tevatron Collider. We select events with one W boson and at least one jet with an identified secondary vertex. In the jets with a secondary vertex we look for a semileptonic decay to a muon. We compare the number of jets with both a secondary vertex and a semileptonic decay, and the kinematic properties of these jets, with the standard model expectation of W plus heavy flavor production and decay. No discrepancy is seen between the observation and the expectation, and we set limits on the production cross section of a B-like hadron with an anomalously high semileptonic branching ratio.Comment: 8 pages, 2 figures, submitted to PRD-RC; replaced to adjust the page forma
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