233 research outputs found

    Seasonal variability of ocean circulation near the Dotson Ice Shelf, Antarctica

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    Recent rapid thinning of West Antarctic ice shelves are believed to be caused by intrusions of warm deep water that induce basal melting and seaward meltwater export. This study uses data from three bottom-mounted mooring arrays to show seasonal variability and local forcing for the currents moving into and out of the Dotson ice shelf cavity. A southward flow of warm, salty water had maximum current velocities along the eastern channel slope, while northward outflows of freshened ice shelf meltwater spread at intermediate depth above the western slope. The inflow correlated with the local ocean surface stress curl. At the western slope, meltwater outflows followed the warm influx along the eastern slope with a ~2–3 month delay. Ocean circulation near Dotson Ice Shelf, affected by sea ice distribution and wind, appears to significantly control the inflow of warm water and subsequent ice shelf melting on seasonal time-scales

    Search for Lepton-Flavor-Violating tau Decays into a Lepton and an f0(980) Meson

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    We search for lepton-flavor-violating tau decays into a lepton (electron or muon) and an f0(980) meson using 671 fb-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. No events are observed and we set the following 90% C.L. upper limits on the branching fraction products: B(tau- -> e-f0(980))*B(f0(980)->pi+pi-) mu-f0(980))*B(f0(980) -> pi+pi-)<3.4x10^-8. This is the first search performed for these modes.Comment: 10 pages, 4 figures, submitted to Phys. Lett.

    Search for B+ -> D*+ pi0 decay

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    We report on a search for the doubly Cabibbo suppressed decay B+ -> D*+ pi0, based on a data sample of 657 million BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider. We find no significant signal and set an upper limit of Br(B+ -> D*+ pi0) < 3.6 x 10^-6 at the 90% confidence level. This limit can be used to constrain the ratio between suppressed and favored B -> D* pi decay amplitudes, r < 0.051, at the 90% confidence level.Comment: 5pages, 2figures, submitted to PRL (v1); PRL published version (v2: minor corrections in the text

    Observation of the ϕ(1680)\phi(1680) and the Y(2175) in e+eϕπ+πe^+ e^- \to \phi\pi^+\pi^-

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    The cross sections for e+eϕπ+πe^+ e^- \to \phi\pi^+\pi^- and e^+ e^- \to \phi \fzero are measured from threshold to s=3.0\sqrt{s}=3.0 GeV\hbox{GeV} using initial state radiation. The analysis is based on a data sample of 673 fb1^{-1} collected on and below the Υ(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ee^+e^- collider. First measurements are reported for the resonance parameters of the ϕ(1680)\phi(1680) in the ϕπ+π\phi\pi^+\pi^- mode: m=(1689±7±10)m=(1689\pm 7\pm 10) MeV/c2c^2 and Γ=(211±14±19)\Gamma=(211\pm 14\pm 19) MeV/c2c^2. A structure at s=2.1GeV/c2\sqrt{s}=2.1 \hbox{GeV}/c^2, corresponding to the so called Y(2175), is observed; its mass and width are determined to be 2079±1328+792079\pm13^{+79}_{-28} MeV/c2c^2 and 192±2361+25MeV/c2192\pm23^{+25}_{-61} \hbox{MeV}/c^2, respectively.Comment: 11 pages, 6 figures. Add one plot. Accepted by Phys.Rev.D(RC

    Measurement of CP asymmetry in Cabibbo suppressed D0 decays

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    We measure the CP-violating asymmetries in decays to the D0 -> K+K- and D0 -> pi+pi- CP eigenstates using 540 fb^{-1} of data collected with the Belle detector at or near the Upsilon(4S) resonance. Cabibbo-favored D0 -> K-pi+ decays are used to correct for systematic detector effects. The results, A_{CP}^{KK} = (-0.43 +- 0.30 +- 0.11)% and A_{CP}^{pipi} = (+0.43 +- 0.52 +- 0.12)%, are consistent with no CP violation.Comment: Submitted to Phys. Lett.

    The COSINE-100 liquid scintillator veto system

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    This paper describes the liquid scintillator veto system for the COSINE-100 dark matter experiment and its performance. The COSINE-100 detector consists of eight NaI(Tl) crystals immersed in 2200 L of linear alkylbenzene-based liquid scintillator. The liquid scintillator tags between 65 and 75% of the internal 40K background in the 2–6 keV energy region. We also describe the background model for the liquid scintillator, which is primarily used to assess its energy calibration and threshold

    Measurement of the cosmic muon annual and diurnal flux variation with the COSINE-100 detector

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    We report measurements of annual and diurnal modulations of the cosmic-ray muon rate in the Yangyang underground laboratory (Y2L) using 952 days of COSINE-100 data acquired between September 2016 and July 2019. A correlation of the muon rate with the atmospheric temperature is observed and its amplitude on the muon rate is determined. The effective atmospheric temperature and muon rate variations are positively correlated with a measured effective temperature coefficient of αT = 0.80 ± 0.11. This result is consistent with a model of meson production in the atmosphere. We also searched for a diurnal modulation in the underground muon rate by comparing one-hour intervals. No significant diurnal modulation of the muon rate was observed

    A Low-Footprint Java-to-Native Compilation Scheme Using Formal Methods

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    Ahead-of-Time and Just-in-Time compilation are common ways to improve runtime performances of restrained systems like Java Card by turning critical Java methods into native code. However, native code is much bigger than Java bytecode, which severely limits or even forbids these practices for devices with memory constraints. In this paper, we describe and evaluate a method for reducing natively-compiled code by suppressing runtime exception check sites, which are emitted when compiling bytecodes that may potentially throw runtime exceptions. This is made possible by completing the Java program with JML annotations, and using a theorem prover in order to formally prove that the compiled methods never throw runtime exceptions. Runtime exception check sites can then safely be removed from the generated native code, as it is proved they will never be entered. We have experimented our approach on several card-range and embedded Java applications, and were able to remove almost all the exception check sites. Results show memory footprints for native code that are up to 70% smaller than the non-optimized version, and sometimes as low than 115% the size of the Java bytecode when compiled for ARM thumb

    School-based prevention for adolescent Internet addiction: prevention is the key. A systematic literature review

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    Adolescents’ media use represents a normative need for information, communication, recreation and functionality, yet problematic Internet use has increased. Given the arguably alarming prevalence rates worldwide and the increasingly problematic use of gaming and social media, the need for an integration of prevention efforts appears to be timely. The aim of this systematic literature review is (i) to identify school-based prevention programmes or protocols for Internet Addiction targeting adolescents within the school context and to examine the programmes’ effectiveness, and (ii) to highlight strengths, limitations, and best practices to inform the design of new initiatives, by capitalizing on these studies’ recommendations. The findings of the reviewed studies to date presented mixed outcomes and are in need of further empirical evidence. The current review identified the following needs to be addressed in future designs to: (i) define the clinical status of Internet Addiction more precisely, (ii) use more current psychometrically robust assessment tools for the measurement of effectiveness (based on the most recent empirical developments), (iii) reconsider the main outcome of Internet time reduction as it appears to be problematic, (iv) build methodologically sound evidence-based prevention programmes, (v) focus on skill enhancement and the use of protective and harm-reducing factors, and (vi) include IA as one of the risk behaviours in multi-risk behaviour interventions. These appear to be crucial factors in addressing future research designs and the formulation of new prevention initiatives. Validated findings could then inform promising strategies for IA and gaming prevention in public policy and education

    Study of \Omega_c^0 and \Omega_c^{*0} Baryons at Belle

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    We report results from a study of the charmed double strange baryons \Omega_c^0 and \Omega_c^{*0} at Belle. The \Omega_c^0 is reconstructed using the \Omega_c^0 --> \Omega^- \pi^+ decay mode, and its mass is measured to be (2693.6 \pm 0.3 {+1.8 \atop -1.5}) MeV/c^2. The \Omega_c^{*0} baryon is reconstructed in the \Omega_c^0 \gamma mode. The mass difference M_{\Omega_c^{*0}} - M_{\Omega_c^0} is measured to be (70.7 \pm 0.9 {+0.1 \atop -0.9}) MeV/c^2. The analysis is performed using 673 fb^{-1} of data on and near the \Upsilon(4S) collected with the Belle detector at the KEKB asymmetric-energy e^+e^- collider.Comment: 11 pages, 5 figures, prepared for 34th International Conference on High Energy Physics (ICHEP 08), Philadelphia, PA, 29 Jul - 5 Aug 200
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