8,133 research outputs found

    Superfluid and Fermi liquid phases of Bose-Fermi mixtures in optical lattices

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    We describe interacting mixtures of ultracold bosonic and fermionic atoms in harmonically confined optical lattices. For a suitable choice of parameters we study the emergence of superfluid and Fermi liquid (non-insulating) regions out of Bose-Mott and Fermi-band insulators, due to finite Boson and Fermion hopping. We obtain the shell structure for the system and show that angular momentum can be transferred to the non-insulating regions from Laguerre-Gaussian beams, which combined with Bragg spectroscopy can reveal all superfluid and Fermi liquid shells.Comment: 4 pages, 2 figure

    A Dynamical Principle For 3D-4D Interlinkage In Salpeter-like Equations

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    The half-century old Markov-Yukawa Transversality Principle (MYTPMYTP) which provides a theoretical rationale for the covariant instantaneous approximation (CIACIA) that underlies all Salpeter-like equations, is generalized to a covariant null-plane ansatz (CNPACNPA). A common characteristic of both formulations is an exact 3D-4D interlinkage of BS amplitudes which facilitates a two-tier description: the 3D form for spectroscopy, and the 4D form for transition amplitudes as 4D loop integrals. Some basic applications of MYTPMYTP on the covariant null plane (quark mass function, vacuum condensates, and decay constants) are given on the lines of earlier applications to these processes under CIACIA. PACS: 03.65.-w ; 03.65.Co ; 11.10.Qr ; 11.10.St Keywords: Markov-Yukawa Transversality Principle (MYTPMYTP); Salpeter-like eqs; Cov Instantaneity Ansatz (CIACIA); Cov Null-Plane Ansatz (CNPACNPA); 3D-4D interlinkage; Vertex function; 4D loopsComment: LaTeX file, 25 pages, to be published in Nuclear Phys.

    Superfluid and Mott Insulating shells of bosons in harmonically confined optical lattices

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    Weakly interacting atomic or molecular bosons in quantum degenerate regime and trapped in harmonically confined optical lattices, exhibit a wedding cake structure consisting of insulating (Mott) shells. It is shown that superfluid regions emerge between Mott shells as a result of fluctuations due to finite hopping. It is found that the order parameter equation in the superfluid regions is not of the Gross-Pitaeviskii type except near the insulator to superfluid boundaries. The excitation spectra in the Mott and superfluid regions are obtained, and it is shown that the superfluid shells posses low energy sound modes with spatially dependent sound velocity described by a local index of refraction directly related to the local superfluid density. Lastly, the Berezinskii-Kosterlitz-Thouless transition and vortex-antivortex pairs are discussed in thin (wide) superfluid shells (rings) limited by three (two) dimensional Mott regions.Comment: 11 pages, 9 figures

    UNDERSTANDING ADVANCES IN WEB TECHNOLOGIES: EVOLUTION FROM WEB 2.0 TO WEB 3.0

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    The current generation of Web applications (Web 2.0) have made them an outright phenomenon in today’s society helping to redefine the way organisations and individuals communicate and collaborate with each other. The purpose of this paper is to conceptualise the evolution of Web technologies from a user perspective. Based on inference from existing studies, this paper attempts to identify the architectural direction that the next generation (Web 3.0) of Web applications would meld itself into. The paper emphasizes limitations of current Web technologies and how future trends may address these limitations by focusing on migration that has been witnessed in the scope of the applications presented and features delivered on the Web from a users’ perspective

    Conjunction Assessment Techniques and Operational Results from the Magnetospheric Multiscale Mission

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    This paper will describe the results that have been obtained to date during the MMS mission concerning conjunction assessment. MMS navigation makes use of a weak-signal GPS-based system: this allows signals to be received even when MMS is flying above the GPS orbits, producing a highly accurate determination of the four MMS orbits. This data is downlinked to the MMS Mission Operations Center (MOC) and used by the Flight Dynamics Operations Area (FDOA) for both maneuver design and conjunction assessment. The MMS fly in tetrahedron formations around apogee, in order to collect simultaneous particles and fields science data. The original plan was to fly tetrahedra between 10 and 160 km in size; however, after Phase 1a of the mission, the science team requested that smaller sizes be flown if feasible. After analysis (to be detailed in a companion paper), a new minimum size of 7 km was decided upon. Flying at this reduced scale size makes conjunction assessment between the MMS spacecraft even more important: the methods that are used by the MMS FDOA to address this problem will be described in the paper, and a summary given of the previous analyses that went into the development of these techniques. Details will also be given of operational experiences to date. Finally, two CA mitigation maneuver types that have been designed (but never yet required to actually be performed) will also be outlined

    Targeted neurostimulation reverses a spatiotemporal biomarker of treatment-resistant depression

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    Major depressive disorder (MDD) is widely hypothesized to result from disordered communication across brain-wide networks. Yet, prior resting-state-functional MRI (rs-fMRI) studies of MDD have studied zero-lag temporal synchrony (functional connectivity) in brain activity absent directional information. We utilize the recent discovery of stereotyped brain-wide directed signaling patterns in humans to investigate the relationship between directed rs-fMRI activity, MDD, and treatment response to FDA-approved neurostimulation paradigm termed Stanford neuromodulation therapy (SNT). We find that SNT over the left dorsolateral prefrontal cortex (DLPFC) induces directed signaling shifts in the left DLPFC and bilateral anterior cingulate cortex (ACC). Directional signaling shifts in the ACC, but not the DLPFC, predict improvement in depression symptoms, and moreover, pretreatment ACC signaling predicts both depression severity and the likelihood of SNT treatment response. Taken together, our findings suggest that ACC-based directed signaling patterns in rs-fMRI are a potential biomarker of MDD

    The 2015 Indian summer monsoon onset - phenomena, forecasting and research flight planning

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    From May to July 2016, as part of the INCOMPASS project, the Facility for Airborne Atmospheric Measurements (FAAM, jointly funded by the Met Office and NERC) BAe-146 research aircraft travelled to India to record key aspects of the Indian summer monsoon onset and evolution. As part of the planning for the campaign, partners in the UK and India took part in a dry-run forecasting exercise during 2015, to assess the reliability of the forecast products and develop a set of flight plans, in advance of the real campaign, and to get a real-time feel for the monsoon onset. 5-day forecasts from the Met Office and the Indian National Centre for Medium Range Weather Forecasting (NCMRWF) showed good skill in terms of predicting the advance of rainfall in regions key for the campaign in north and south India, and captured transitions from active (wet) monsoon conditions to break (dry) periods and back again. Key phenomena seen during the dry-run exercise include (1) a western disturbance, which had a major effect on the extreme pre-monsoon heatwave conditions over India; (2) dry intrusions, which are thought to be important in the progression of the monsoon onset against the synoptic flow; and (3) cyclones Ashobaa and Komen

    X-Ray tomography study on porosity and particle size distribution in In Situ Al-4.5Cu-5TiB2 Semisolid rolled composites

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    X-ray computed tomography (XCT) was used for three-dimensional (3D) visualization of the internal microstructure and quantification of the porosity and second-phase particles in Al-4.5Cu-5TiB2 composites prepared by an in situ liquid metallurgy casting route. The as-cast composites were subjected to hot rolling and mushy-state rolling for deagglomeration and to achieve a uniform distribution of CuAl2-TiB2 particle clusters. Qualitative results obtained by scanning electron microscopy (SEM) and quantitative results obtained by XCT both showed that mushy-state rolling as well as hot rolling resulted in fragmentation and a homogeneous distribution of the CuAl2-TiB2 particle clusters, with the mushy-state-rolled composite exhibiting the highest number of smaller-size particles. The porosity was increased in both rolling conditions through debonding of particles due to the compressive force during solid-state deformation along with the quick solidification of the solute-rich liquid during mushy-state rolling. These results show that application of secondary processes such as hot-rolling and mushy-state rolling can help to achieve a relatively more uniform particle distribution in Al-4.5Cu-5TiB2 in situ composite

    Breast Cancer Fatalism: The Role of Women\u27s Perceptions of the Health Care System

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    Cancer fatalism, which can be understood as the belief that cancer is a death sentence, has been found to be a deterrent to preventive cancer screening participation. This study examines factors associated with breast cancer fatalism among women. We analyzed data from a 2003 survey of women 40 years of age. The survey collected information about respondents\u27 knowledge and attitudes regarding breast health. Analyses compared the characteristics of women who reported and those who did not report a fatalistic attitude. Women with a fatalistic attitude were more likely to be African American, to have a family history of breast cancer, to rate their quality of care as fair or poor, to believe that not much could be done to prevent breast cancer, to believe that breast cancer could not be cured if found early, and to believe that treatment could be worse than the disease
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