493 research outputs found

    Mean-field analysis of the stability of a K-Rb Fermi-Bose mixture

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    We compare the experimental stability diagram of a Fermi-Bose mixture of K-40 and Rb-87 atoms with attractive interaction to the predictions of a mean-field theoretical model. We discuss how this comparison can be used to give a better estimate of the interspecies scattering length, which is currently known from collisional measurements with larger uncertainty.Comment: 5 pages, 4 figure

    Search for dark photons as candidates for Dark Matter with FUNK

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    An additional U(1) symmetry predicted in theories beyond the Standard Model of particle physics can give rise to hidden (dark) photons. Depending on the mass and density of these hidden photons, they could account for a large fraction of the Dark Matter observed in the Universe. When passing through an interface of materials with different dielectric properties, hidden photons are expected to produce a tiny flux of photons. The wavelength of these photons is directly related to the mass of the hidden photons. In this contribution we report on measurements covering the visible and near-UV spectrum, corresponding to a dark photon mass in the eV range. The data were taken with the FUNK experiment using a spherical mirror of ~14m2 total area built up of 36 aluminum segments

    Template-stripped gold surfaces with 0.4 nm rms roughness suitable for force measurements. Application to the Casimir force in the 20-100 nm range

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    Using a template-stripping method, macroscopic gold surfaces with root-mean-square (rms) roughness less than 0.4 nm have been prepared, making them useful for studies of surface interactions in the nanometer range. The utility of such substrates is demonstrated by measurements of the Casimir force at surface separations between 20 and 100 nm, resulting in good agreement with theory. The significance and quantification of this agreement is addressed, as well as some methodological aspects regarding the measurement of the Casimir force with high accuracy.Comment: 7 figure

    5-HT2C Agonists Modulate Schizophrenia-Like Behaviors in Mice

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    All FDA-approved antipsychotic drugs (APDs) target primarily dopamine D2 or serotonin (5-HT2A) receptors, or both; however, these medications are not universally effective, they may produce undesirable side effects, and provide only partial amelioration of negative and cognitive symptoms. The heterogeneity of pharmacological responses in schizophrenic patients suggests that additional drug targets may be effective in improving aspects of this syndrome. Recent evidence suggests that 5-HT2C receptors may be a promising target for schizophrenia since their activation reduces mesolimbic nigrostriatal dopamine release (which conveys antipsychotic action), they are expressed almost exclusively in CNS, and have weight-loss-promoting capabilities. A difficulty in developing 5-HT2C agonists is that most ligands also possess 5-HT2B and/or 5-HT2A activities. We have developed selective 5-HT2C ligands and herein describe their preclinical effectiveness for treating schizophrenia-like behaviors. JJ-3-45, JJ-3-42, and JJ-5-34 reduced amphetamine-stimulated hyperlocomotion, restored amphetamine-disrupted prepulse inhibition, improved social behavior, and novel object recognition memory in NMDA receptor hypofunctioning NR1-knockdown mice, and were essentially devoid of catalepsy. However, they decreased motivation in a breakpoint assay and did not promote reversal learning in MK-801-treated mice. Somewhat similar effects were observed with lorcaserin, a 5-HT2C agonist with potent 5-HT2B and 5-HT2A agonist activities, which is approved for treating obesity. Microdialysis studies revealed that both JJ-3-42 and lorcaserin reduced dopamine efflux in the infralimbic cortex, while only JJ-3-42 decreased it in striatum. Collectively, these results provide additional evidence that 5-HT2C receptors are suitable drug targets with fewer side effects, greater therapeutic selectivity, and enhanced efficacy for treating schizophrenia and related disorders than current APDs. Neuropsychopharmacology advance online publication, 12 April 2017; doi:10.1038/npp.2017.52

    Modern topics in theoretical nuclear physics

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    Over the past five years there have been profound advances in nuclear physics based on effective field theory and the renormalization group. In this brief, we summarize these advances and discuss how they impact our understanding of nuclear systems and experiments that seek to unravel their unknowns. We discuss future opportunities and focus on modern topics in low-energy nuclear physics, with special attention to the strong connections to many-body atomic and condensed matter physics, as well as to astrophysics. This makes it an exciting era for nuclear physics.Comment: 8 pages, 1 figure, prepared for the Nuclear Physics Town Hall Meeting at TRIUMF, Sept. 9-10, 2005, comments welcome, references adde

    The KASCADE-Grande Experiment and the LOPES Project

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    KASCADE-Grande is the extension of the multi-detector setup KASCADE to cover a primary cosmic ray energy range from 100 TeV to 1 EeV. The enlarged EAS experiment provides comprehensive observations of cosmic rays in the energy region around the knee. Grande is an array of 700 x 700 sqm equipped with 37 plastic scintillator stations sensitive to measure energy deposits and arrival times of air shower particles. LOPES is a small radio antenna array to operate in conjunction with KASCADE-Grande in order to calibrate the radio emission from cosmic ray air showers. Status and capabilities of the KASCADE-Grande experiment and the LOPES project are presented.Comment: To appear in Nuclear Physics B, Proceedings Supplements, as part of the volume for the CRIS 2004, Cosmic Ray International Seminar: GZK and Surrounding

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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