6,233 research outputs found

    Structure and Decay Properties of Th Isotopes Using E-RMFT Formalism

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    In the present scenario, the search for the thermally fissile nuclei is crucial and also important not only for the research background of nuclear physics but also for the great social and economic impact on the country. Many theoretical works have been performed to analyze a series of Th and U-isotopes and found that some of these isotopes are stable against α-decays and spontaneous fission. Here, we have chosen the isotopic chain of Th-nuclei for the present analysis using relativistic mean-field formalism. The work also explores a few stable isotopes in this region of the nuclear landscape, which is crucial for understanding the exotic region of the nuclear landscape. The objective of this work is to study the bulk properties such as binding energies, root mean square charge radii, neutron-proton radii, neutron skin-thickness as well as intrinsic properties such as excitation energy and specific heat for the 216-238Th-isotopic chain. Furthermore, the stability of these isotopes is investigated through their possible decay chain analysis. The relativistic mean-field theory was used to obtain the nuclear bulk properties, namely, binding energies, root-mean-square charge radii, neutron skin-thickness, and excitation energy. The steady solution of the temperature-dependent effective relativistic mean-field equations was obtained self-consistently by taking different inputs of the initial deformations. All the calculations were done for NL3, FSUGarnet and IOPB-I parameter sets for 216-238Th-isotopes. The decay energy of α (Qα) and β-decay (Qβ) were calculated from the binding energies and were further used to obtain the corresponding half-lives. We have analyzed the structural and decay properties of 216-238Th isotopes. The excitation energy and specific heat are also estimated for these considered nuclei by using the temperature-dependent effective relativistic mean-field (E-RMFT) formalism for NL3, FSUGarnet and IOPB-I parameters sets. The calculated results are compared with the available experimental data and found similar observations for all the parameter sets at a given temperature. The excitation energy study signifies the shell melting point where maybe the shape transition occurs. Three phenomenological formulae such as Viola-Seaborg, Royer and modified universal decay law are adopted for the calculation of α-decay half-lives. We found lower values of α-decay half-lives indicating a higher rate of β-decay for the isotopic chain

    Random access quantum information processors

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    Qubit connectivity is an important property of a quantum processor, with an ideal processor having random access -- the ability of arbitrary qubit pairs to interact directly. Here, we implement a random access superconducting quantum information processor, demonstrating universal operations on a nine-bit quantum memory, with a single transmon serving as the central processor. The quantum memory uses the eigenmodes of a linear array of coupled superconducting resonators. The memory bits are superpositions of vacuum and single-photon states, controlled by a single superconducting transmon coupled to the edge of the array. We selectively stimulate single-photon vacuum Rabi oscillations between the transmon and individual eigenmodes through parametric flux modulation of the transmon frequency, producing sidebands resonant with the modes. Utilizing these oscillations for state transfer, we perform a universal set of single- and two-qubit gates between arbitrary pairs of modes, using only the charge and flux bias of the transmon. Further, we prepare multimode entangled Bell and GHZ states of arbitrary modes. The fast and flexible control, achieved with efficient use of cryogenic resources and control electronics, in a scalable architecture compatible with state-of-the-art quantum memories is promising for quantum computation and simulation.Comment: 7 pages, 5 figures, supplementary information ancillary file, 21 page

    Hydrographic changes in the Agulhas Recirculation Region during the late Quaternary

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    The strength of Southern Hemisphere westerlies, as well as the positions of the subtropical front (STF), Agulhas Current (AC) and Agulhas Return Current (ARC) control the hydrography of the southwestern Indian Ocean. Although equatorward migration of the STF and reduction in Agulhas leakage were reported during the last glacial period, the fate of ARC during the last glacial–interglacial cycle is not clear. Therefore, in order to understand changes in the position and strength of ARC during the last glacial–interglacial cycle, here we reconstruct hydrographic changes in the southwestern Indian Ocean from temporal variation in planktic foraminiferal abundance, stable isotopic ratio (δ<sup>18</sup>O) and trace elemental ratio (Mg/Ca) of planktic foraminifera <i>Globigerina bulloides</i> in a core collected from the Agulhas Recirculation Region (ARR) in the southwestern Indian Ocean. Increased abundance of <i>G. bulloides</i> suggests that the productivity in the southwestern Indian Ocean increased during the last glacial period which confirms previous reports of high glacial productivity in the Southern Ocean. The increased productivity was likely driven by the intensified Southern Hemisphere westerlies supported by an equatorward migration of the subtropical front. Increase in relative abundance of <i>Neogloboquadrina incompta</i> suggests seasonally strong thermocline and enhanced advection of southern source water in the southwestern Indian Ocean as a result of strengthened ARC, right through MIS 4 to MIS 2, during the last glacial period. Therefore, it is inferred that over the last glacial–interglacial cycle, the hydrography of the southwestern Indian Ocean was driven by strengthened westerlies, ARC as well as a migrating subtropical front

    Timing and spectral studies of the transient X-ray pulsar EXO 053109-6609.2 with ASCA and Beppo-SAX

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    We report timing and spectral properties of the transient Be X-ray pulsar EXO 053109--6609.2 studied using observations made with the ASCA and BeppoSAX observatories. Though there must have been at least one spin-down episode of the pulsar since its discovery, the new pulse period measurements show a monotonic spin-up trend since 1996. The pulse profile is found to have marginal energy dependence. There is also evidence for strong luminosity dependence of the pulse profile, a single peaked profile at low luminosity that changes to a double peaked profile at high luminosity. This suggests a change in the accretion pattern at certain luminosity level. The X-ray spectrum is found to consist of a simple power-law with photon index in the range of 0.4--0.8. At high intensity level the spectrum also shows presence of weak iron emission line.Comment: 12 pages, 8 figures, Accepted for publication in Ap

    Quantum Distribution of Gaussian Keys with Squeezed States

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    A continuous key distribution scheme is proposed that relies on a pair of canonically conjugate quantum variables. It allows two remote parties to share a secret Gaussian key by encoding it into one of the two quadrature components of a single-mode electromagnetic field. The resulting quantum cryptographic information vs disturbance tradeoff is investigated for an individual attack based on the optimal continuous cloning machine. It is shown that the information gained by the eavesdropper then simply equals the information lost by the receiver.Comment: 5 pages, RevTe

    National or population level interventions addressing the social determinants of mental health - an umbrella review

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    Background: Social circumstances in which people live and work impact the population’s mental health. We aimed to synthesise evidence identifying effective interventions and policies that influence the social determinants of mental health at national or scaled population level. We searched five databases (Cochrane Library, Global Health, MEDLINE, EMBASE and PsycINFO) between Jan 1st 2000 and July 23rd 2019 to identify systematic reviews of population-level interventions or policies addressing a recognised social determinant of mental health and collected mental health outcomes. There were no restrictions on country, sub-population or age. A narrative overview of results is provided. Quality assessment was conducted using Assessment of Multiple Systematic Reviews (AMSTAR 2). This study was registered on PROSPERO (CRD42019140198). Results: We identified 20 reviews for inclusion. Most reviews were of low or critically low quality. Primary studies were mostly observational and from higher income settings. Higher quality evidence indicates more generous welfare benefits may reduce socioeconomic inequalities in mental health outcomes. Lower quality evidence suggests unemployment insurance, warm housing interventions, neighbourhood renewal, paid parental leave, gender equality policies, community-based parenting programmes, and less restrictive migration policies are associated with improved mental health outcomes. Low quality evidence suggests restriction of access to lethal means and multi-component suicide prevention programmes are associated with reduced suicide risk. Conclusion: This umbrella review has identified a small and overall low-quality evidence base for population level interventions addressing the social determinants of mental health. There are significant gaps in the evidence base for key policy areas, which limit ability of national policymakers to understand how to effectively improve population mental health

    Flavor symmetry breaking and scaling for improved staggered actions in quenched QCD

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    We present a study of the flavor symmetry breaking in the pion spectrum for various improved staggered fermion actions. To study the effects of link fattening and tadpole improvement, we use three different variants of the p4 action - p4fat3, p4fat7, and p4fat7tad. These are compared to Asqtad and also to naive staggered. To study the pattern of symmetry breaking, we measure all 15 meson masses in the 4-flavor staggered theory. The measurements are done on a quenched gauge background, generated using a one-loop improved Symanzik action with β=10/g2=7.40,7.75,\beta=10/g^2 = 7.40, 7.75, and 8.00, corresponding to lattice spacings of approximately a = .31 fm., .21 fm., and .14 fm. We also study how the lattice scale set by the ρ\rho mass on each of these ensembles compares to one set by the static quark potential.Comment: 18 pages, 6 figure

    The feasible generation of entangled photon states by using linear optical elements

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    We present a feasible scheme to produce a polarization-entangled photon states 12(H>V>+V>H>)\frac{1}{\sqrt{2}}(|H>|V>+|V>|H>) in a controllable way. This scheme requires single-photon sources, linear optical elements and photon detectors. It generates the entanglement of spatially separated photons. The interaction takes place in the photon detectors. We also show that the same idea can be used to produce the entangled NN-photon state 12(0,N>+N,0>)\frac{1}{\sqrt{2}}(|0,N>+|N,0>)Comment: to appear in PR

    Comparative evaluation of real-time PCR and conventional RT-PCR during two year surveillance for Influenza and RSV among children with acute respiratory infections in Kolkata reveals distinct seasonality of infection

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    Acute respiratory tract infections (ARTI) are one of the most common cause of morbidity and mortality in young children all over the world. Influenza and Respiratory Syncytial viruses (RSV) are the predominant etiology during seasonal epidemics and thus rapid and sensitive molecular tests for screening &amp; timely identification of epidemics are required. In this study we report comparison of real time PCR (Q-PCR) with conventional RT-PCR for parallel identification of Influenza A or B (Inf-A or -B) and RSV. A total of 1091 respiratory samples were examined from children with suspected ARTI during January 2007- December 2008. Of these 1091 samples, 275 (25.21%) were positive for either Influenza or RSV by Q-PCR compared to 262 (24%) positives by RT-PCR. Overall Inf-A, -B and RSV were detected in a total of 121 (11.075%), 59 (5.38%) and 95 (8.68%) samples respectively. In spite of overlapping clinical symptoms, RSV and Influenza showed distinct seasonal peaks. Inf-A positively and RSV, negatively correlated with rainfall and temperature. No distinct seasonality was observed in Inf-B infections. This is the first report of a systemic surveillance of respiratory viruses with seasonal correlation and prevalence rate from Eastern India. The two year comparative analysis also confirmed feasibility of using Q-PCR in developing countries, which will not only improve scope for prevention of epidemics but also provide crucial epidemiological data from the tropical regions
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