2,808 research outputs found

    Few-Body States in Fermi-Systems and Condensation Phenomena

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    Residual interactions in many particle systems lead to strong correlations. A multitude of spectacular phenomenae in many particle systems are connected to correlation effects in such systems, e.g. pairing, superconductivity, superfluidity, Bose-Einstein condensation etc. Here we focus on few-body bound states in a many-body surrounding.Comment: 10 pages, proceedings 1st Asian-Pacific Few-Body Conference, needs fbssuppl.sty of Few-Body System

    Evidence for an exotic S=-2, Q=-2 baryon resonance in proton-proton collisions at the CERN SPS

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    Results of resonance searches in the Xi - pi -, Xi - pi +, Xi -bar+ pi -, and Xi -bar+ pi + invariant mass spectra in proton-proton collisions at sqrt[s]=17.2 GeV are presented. Evidence is shown for the existence of a narrow Xi - pi - baryon resonance with mass of 1.862±0.002 GeV/c2 and width below the detector resolution of about 0.018 GeV/c2. The significance is estimated to be above 4.2 sigma . This state is a candidate for the hypothetical exotic Xi --3/2 baryon with S=-2, I=3 / 2, and a quark content of (dsdsu-bar). At the same mass, a peak is observed in the Xi - pi + spectrum which is a candidate for the Xi 03/2 member of this isospin quartet with a quark content of (dsusd-bar). The corresponding antibaryon spectra also show enhancements at the same invariant mass

    Early prediction of upper limb functioning after stroke using clinical bedside assessments: a prospective longitudinal study.

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    Early and accurate prediction of recovery is needed to assist treatment planning and inform patient selection in clinical trials. This study aimed to develop a prediction algorithm using a set of simple early clinical bedside measures to predict upper limb capacity at 3-months post-stroke. A secondary analysis of Stroke Arm Longitudinal Study at Gothenburg University (SALGOT) included 94 adults (mean age 68 years) with upper limb impairment admitted to stroke unit). Cluster analysis was used to define the endpoint outcome strata according to the 3-months Action Research Arm Test (ARAT) scores. Modelling was carried out in a training (70%) and testing set (30%) using traditional logistic regression, random forest models. The final algorithm included 3 simple bedside tests performed 3-days post stroke: ability to grasp, to produce any measurable grip strength and abduct/elevate shoulder. An 86-94% model sensitivity, specificity and accuracy was reached for differentiation between poor, limited and good outcome. Additional measurement of grip strength at 4 weeks post-stroke and haemorrhagic stroke explained the underestimated classifications. External validation of the model is recommended. Simple bedside assessments have advantages over more lengthy and complex assessments and could thereby be integrated into routine clinical practice to aid therapy decisions, guide patient selection in clinical trials and used in data registries

    The one-pion-exchange three-nucleon force and the AyA_y puzzle

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    We consider a new three-nucleon force generated by the exchange of one pion in the presence of a 2N correlation. The underlying irreducible diagram has been recently suggested by the authors as a possible candidate to explain the puzzle of the vector analyzing powers AyA_y and iT11iT_{11} for nucleon-deuteron scattering. Herein, we have calculated the elastic neutron-deuteron differential cross section, AyA_y, iT11iT_{11}, T20T_{20}, T21T_{21}, and T22T_{22} below break-up threshold by accurately solving the Alt-Grassberger-Sandhas equations with realistic interactions. We have also studied how AyA_y evolves below 30 MeV. The results indicate that this new 3NF diagram provides one possible additional contribution, with the correct spin-isospin structure, for the explanation of the origin of this puzzle.Comment: revised version: We have also studied how Ay evolves below 30 MeV, 4 Pages (twocolumn), 2 figures, uses psfig, RevTe

    Studying Cat (Felis catus) Diabetes: Beware of the Acromegalic Imposter

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    Naturally occurring diabetes mellitus (DM) is common in domestic cats (Felis catus). It has been proposed as a model for human Type 2 DM given many shared features. Small case studies demonstrate feline DM also occurs as a result of insulin resistance due to a somatotrophinoma. The current study estimates the prevalence of hypersomatotropism or acromegaly in the largest cohort of diabetic cats to date, evaluates clinical presentation and ease of recognition. Diabetic cats were screened for hypersomatotropism using serum total insulin-like growth factor-1 (IGF-1; radioimmunoassay), followed by further evaluation of a subset of cases with suggestive IGF-1 (>1000 ng/ml) through pituitary imaging and/ or histopathology. Clinicians indicated pre-test suspicion for hypersomatotropism. In total 1221 diabetic cats were screened; 319 (26.1%) demonstrated a serum IGF-1>1000 ng/ml (95% confidence interval: 23.6-28.6%). Of these cats a subset of 63 (20%) underwent pituitary imaging and 56/63 (89%) had a pituitary tumour on computed tomography; an additional three on magnetic resonance imaging and one on necropsy. These data suggest a positive predictive value of serum IGF-1 for hypersomatotropism of 95% (95% confidence interval: 90-100%), thus suggesting the overall hypersomatotropism prevalence among UK diabetic cats to be 24.8% (95% confidence interval: 21.2-28.6%). Only 24% of clinicians indicated a strong pre-test suspicion; most hypersomatotropism cats did not display typical phenotypical acromegaly signs. The current data suggest hypersomatotropism screening should be considered when studying diabetic cats and opportunities exist for comparative acromegaly research, especially in light of the many detected communalities with the human disease

    Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76$ TeV

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    In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v2v_2 reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb-Pb collisions at sNN=2.76\sqrt{s_{_{\rm NN}}} =2.76 TeV. The two-particle correlator ⟹cos⁥(φα−φÎČ)⟩\langle \cos(\varphi_\alpha - \varphi_\beta) \rangle, calculated for different combinations of charges α\alpha and ÎČ\beta, is almost independent of v2v_2 (for a given centrality), while the three-particle correlator ⟹cos⁥(φα+φÎČ−2Κ2)⟩\langle \cos(\varphi_\alpha + \varphi_\beta - 2\Psi_2) \rangle scales almost linearly both with the event v2v_2 and charged-particle pseudorapidity density. The charge dependence of the three-particle correlator is often interpreted as evidence for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. However, its measured dependence on v2v_2 points to a large non-CME contribution to the correlator. Comparing the results with Monte Carlo calculations including a magnetic field due to the spectators, the upper limit of the CME signal contribution to the three-particle correlator in the 10-50% centrality interval is found to be 26-33% at 95% confidence level.Comment: 20 pages, 6 captioned figures, 1 tables, authors from page 15, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/382

    Optical model potentials involving loosely bound p-shell nuclei around 10 MeV/A

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    We present the results of a search for optical model potentials for use in the description of elastic scattering and transfer reactions involving stable and radioactive p-shell nuclei. This was done in connection with our program to use transfer reactions to obtain data for nuclear astrophysics, in particular for the determination of the astrophysical S_17 factor for 7Be(p,\gamma)8B using two (7Be,8B) proton transfer reactions. Elastic scattering was measured using 7Li, 10B, 13C and 14N projectiles on 9Be and 13C targets at or about E/A=10 MeV/nucleon. Woods-Saxon type optical model potentials were extracted and are compared with potentials obtained from a microscopic double folding model. We use these results to find optical model potentials for unstable nuclei with emphasis on the reliability of the description they provide for peripheral proton transfer reactions. We discuss the uncertainty introduced by the procedure in the prediction of the DWBA cross sections for the (7Be,8B) reactions used in extracting the astrophysical factor S_17(0).Comment: 16 pages, LaTEX file, 9 figures (PostScript files

    Measurement of the production of charm jets tagged with D0^{0} mesons in pp collisions at s\sqrt{s}= 7 TeV

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    The production of charm jets in proton-proton collisions at a center-of-mass energy of s=7\sqrt{s}=7 TeV was measured with the ALICE detector at the CERN Large Hadron Collider. The measurement is based on a data sample corresponding to a total integrated luminosity of 6.236.23 nb−1{\rm nb}^{-1}, collected using a minimum-bias trigger. Charm jets are identified by the presence of a D0^0 meson among their constituents. The D0^0 mesons are reconstructed from their hadronic decay D0→^0\rightarrowK−π+^{-}\pi^{+}. The D0^0-meson tagged jets are reconstructed using tracks of charged particles (track-based jets) with the anti-kTk_{\mathrm{T}} algorithm in the jet transverse momentum range 5<pT,jetch<305<p_{\rm{T,jet}}^{\mathrm{ch}}<30 GeV/c{\rm GeV/}c and pseudorapidity ∣ηjet∣<0.5|\eta_{\rm jet}|<0.5. The fraction of charged jets containing a D0^0-meson increases with pT,jetchp_{\rm{T,jet}}^{\rm{ch}} from 0.042±0.004 (stat)±0.006 (syst)0.042 \pm 0.004\, \mathrm{(stat)} \pm 0.006\, \mathrm{(syst)} to 0.080±0.009 (stat)±0.008 (syst)0.080 \pm 0.009\, \rm{(stat)} \pm 0.008\, \rm{(syst)}. The distribution of D0^0-meson tagged jets as a function of the jet momentum fraction carried by the D0^0 meson in the direction of the jet axis (z∣∣chz_{||}^{\mathrm{ch}}) is reported for two ranges of jet transverse momenta, 5<pT,jetch<155<p_{\rm{T,jet}}^{\rm{ch}}<15 GeV/c{\rm GeV/}c and 15<pT,jetch<3015<p_{\rm{T,jet}}^{\rm{ch}}<30 GeV/c{\rm GeV/}c in the intervals 0.2<z∣∣ch<1.00.2<z_{||}^{\rm{ch}}<1.0 and 0.4<z∣∣ch<1.00.4<z_{||}^{\rm{ch}}<1.0, respectively. The data are compared with results from Monte Carlo event generators (PYTHIA 6, PYTHIA 8 and Herwig 7) and with a Next-to-Leading-Order perturbative Quantum Chromodynamics calculation, obtained with the POWHEG method and interfaced with PYTHIA 6 for the generation of the parton shower, fragmentation, hadronisation and underlying event.Comment: 29 pages, 8 captioned figures, 3 tables, authors from page 24, published version, figures at http://alice-publications.web.cern.ch/node/525
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