442 research outputs found

    Neutrino Detection using Lead Perchlorate

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    We discuss the possibility of using lead perchlorate as a neutrino detector. The primary neutrino interactions are given along with some relevant properties of the material.Comment: 2 pages, 2 figures, TAUP-99, TEX fil

    Scaling Laws and Transient Times in 3He Induced Nuclear Fission

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    Fission excitation functions of compound nuclei in a mass region where shell effects are expected to be very strong are shown to scale exactly according to the transition state prediction once these shell effects are accounted for. The fact that no deviations from the transition state method have been observed within the experimentally investigated excitation energy regime allows one to assign an upper limit for the transient time of 10 zs.Comment: 7 pages, TeX type, psfig, submitted to Phys. Rev. C, also available at http://csa5.lbl.gov/moretto/ps/he3_paper.p

    Rabies screen reveals GPe control of cocaine-triggered plasticity.

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    Identification of neural circuit changes that contribute to behavioural plasticity has routinely been conducted on candidate circuits that were preselected on the basis of previous results. Here we present an unbiased method for identifying experience-triggered circuit-level changes in neuronal ensembles in mice. Using rabies virus monosynaptic tracing, we mapped cocaine-induced global changes in inputs onto neurons in the ventral tegmental area. Cocaine increased rabies-labelled inputs from the globus pallidus externus (GPe), a basal ganglia nucleus not previously known to participate in behavioural plasticity triggered by drugs of abuse. We demonstrated that cocaine increased GPe neuron activity, which accounted for the increase in GPe labelling. Inhibition of GPe activity revealed that it contributes to two forms of cocaine-triggered behavioural plasticity, at least in part by disinhibiting dopamine neurons in the ventral tegmental area. These results suggest that rabies-based unbiased screening of changes in input populations can identify previously unappreciated circuit elements that critically support behavioural adaptations

    Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

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    This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

    Bone sialoprotein immobilized in collagen type I enhances bone regeneration in vitro and in vivo

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    The use of bioactive molecules is a promising approach to enhance the bone healing properties of biomaterials. The aim of this study was to define the role of bone sialoprotein (BSP) immobilized in collagen type I in various settings. In vitro studies with human primary osteoblasts in mono- or in co-culture with endothelial cells demonstrated a slightly increased gene expression of osteogenic markers as well as an increased proliferation rate in osteoblasts after application of BSP immobilized in collagen type I. Two critical size bone defect models were used to analyze bone regeneration. BSP incorporated in collagen type I increased bone regeneration only marginally at one concentration in a calvarial defect model. To induce the mechanical stability, three-dimensional printing was used to produce a stable porous cylinder of polylactide. The cylinder was filled with collagen type I and immobilized BSP and implanted into a femoral defect of critical size in rats. This hybrid material was able to significantly induce bone regeneration. Our study clearly shows the osteogenic effect of BSP when combined with collagen type I as carrier and thereby offers various approaches and options for its use as bioactive molecule in bone substitute materials

    A comparison of shear bond strength of brackets bonded to zirconia

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    Purpose: The objective of this study was to compare the shear bond strength (SBS) of ceramic orthodontic brackets bonded to highly translucent zirconia surfaces following the use of two different primers. Materials and methods: Three types of highly translucent zirconia crowns, Cercon xt ML, e.max ZirCAD, and STML-ML Katana Zirconia, were milled, sandblasted, and primed using two zirconia primers, Monobond Etch and Prime and Z-Prime Plus. A ceramic bracket (Radiance) was bonded onto the facial surface of each crown. Shear bond strength was evaluated using a universal testing machine. Results: There was no significant overall difference across the six experimental groups regarding shear bond strength. The use of the two tested zirconia primers resulted in comparable and clinically acceptable shear bond strengths. Conclusions: Both tested zirconia primers were associated with adequate bond strength when bonding a ceramic orthodontic bracket to the three highly translucent zirconia substrates

    Patient Perspectives on Performance of a Smartphone App for Atrial FibrillationSelf-Management

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    Introduction: AF self-care requires patients to perform daily self-monitoring for symptoms, practice decision making to address symptom changes, and adhere to prescribed medication, diet, physical activity, and follow-up care. Technology can facilitate these critical self-care behaviors and ultimately improve patient outcomes. We assessed atrial fibrillation (AF) patients' experiences with a smartphone application (app) for AF self-management. Methods: A focus group with 9 AF patients and app users was conducted and analyzed using qualitative research methods. The focus group was recorded, transcribed, and coded using a priori and inductive coding strategies. Participant responses for each code were synthesized to identify primary themes. Results: We identified four superordinate themes from patients' experiences: (1) disconnect between tool and its intended use; (2) app as acknowledged tool for adherence; (3) knowledge as empowerment; (3) motives: self-interest vs supporting research. Results from this qualitative study underscore the need to clarify the app's intended use and to better accommodate patients with different AF experiences. The disconnect between a tool and its intended use can generate frustration for users. Discussion: The study reinforces that participants not only see how the app is a tool for adherence; they also see knowledge they gain via the app as empowering, suggesting a correlation between app use and self-efficacy

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

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    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
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