6,308 research outputs found

    Natural convection with mixed insulating and conducting boundary conditions: low and high Rayleigh numbers regimes

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    We investigate the stability and dynamics of natural convection in two dimensions, subject to inhomogeneous boundary conditions. In particular, we consider a Rayleigh-B\`enard (RB) cell, where the horizontal top boundary contains a periodic sequence of alternating thermal insulating and conducting patches, and we study the effects of the heterogeneous pattern on the global heat exchange, both at low and high Rayleigh numbers. At low Rayleigh numbers, we determine numerically the transition from a regime characterized by the presence of small convective cells localized at the inhomogeneous boundary to the onset of bulk convective rolls spanning the entire domain. Such a transition is also controlled analytically in the limit when the boundary pattern length is small compared with the cell vertical size. At higher Rayleigh number, we use numerical simulations based on a lattice Boltzmann method to assess the impact of boundary inhomogeneities on the fully turbulent regime up to Ra∼1010Ra \sim 10^{10}

    No-Core Shell Model for Nuclear Systems with Strangeness

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    We report on a novel ab initio approach for nuclear few- and many-body systems with strangeness. Recently, we developed a relevant no-core shell model technique which we successfully applied in first calculations of lightest Λ\Lambda hypernuclei. The use of a translationally invariant finite harmonic oscillator basis allows us to employ large model spaces, compared to traditional shell model calculations, and use realistic nucleon-nucleon and nucleon-hyperon interactions (such as those derived from EFT). We discuss formal aspects of the methodology, show first demonstrative results for Λ3{}_{\Lambda}^3H, Λ4{}_{\Lambda}^4H and Λ4{}^4_\LambdaHe, and give outlook.Comment: 4 pages, 3 figures; Proceedings of the 22nd European Conference on Few Body Problems in Physics, 9 - 13 September, 2013, Cracow, Polan

    Unconventional superfluid order in the FF-band of a bipartite optical square lattice

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    We report on the first observation of bosons condensed into the energy minima of an FF-band of a bipartite square optical lattice. Momentum spectra indicate that a truly complex-valued staggered angular momentum superfluid order is established. The corresponding wave function is composed of alternating local F2x3−3x+iF2y3−3yF_{2x^3-3x} + i F_{2y^3-3y}-orbits and local SS-orbits residing in the deep and shallow wells of the lattice, which are arranged as the black and white areas of a checkerboard. A pattern of staggered vortical currents arises, which breaks time reversal symmetry and the translational symmetry of the lattice potential. We have measured the populations of higher order Bragg peaks in the momentum spectra for varying relative depths of the shallow and deep lattice wells and find remarkable agreement with band calculations.Comment: 4 pages, 3 figure

    An STM perspective on hexaborides: Surface states of the Kondo insulator SmB6_6

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    Compounds within the hexaboride class of materials exhibit a wide variety of interesting physical phenomena, including polaron formation and quadrupolar order. In particular, SmB6_6 has recently drawn attention as it is considered a prototypical topological Kondo insulator. Evidence in favor of this concept, however, has proven experimentally difficult and controversial, partly because of the required temperatures and energy resolution. Here, a powerful tool is Scanning Tunneling Microscopy (STM) with its unique ability to give local, microscopic information that directly relates to the one-particle Green's function. Yet, STM on hexaborides is met with its own set of challenges. This article attempts to review the progress in STM investigations on hexaborides, with emphasis on SmB6_6 and its intriguing properties.Comment: unrevised version, published version is open acces

    Drugs for neglected diseases: a failure of the market and a public health failure?

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    Infectious diseases cause the suffering of hundreds of millions of people, especially in tropical and subtropical areas. Effective, affordable and easy-to-use medicines to fight these diseases are nearly absent. Although science and technology are sufficiently advanced to provide the necessary medicines, very few new drugs are being developed. However, drug discovery is not the major bottleneck. Today's R&D-based pharmaceutical industry is reluctant to invest in the development of drugs to treat the major diseases of the poor, because return on investment cannot be guaranteed. With national and international politics supporting a free market-based world order, financial opportunities rather than global health needs guide the direction of new drug development. Can we accept that the dearth of effective drugs for diseases that mainly affect the poor is simply the sad but inevitable consequence of a global market economy? Or is it a massive public health failure, and a failure to direct economic development for the benefit of society? An urgent reorientation of priorities in drug development and health policy is needed. The pharmaceutical industry must contribute to this effort, but national and international policies need to direct the global economy to address the true health needs of society. This requires political will, a strong commitment to prioritize health considerations over economic interests, and the enforcement of regulations and other mechanisms to stimulate essential drug development. New and creative strategies involving both the public and the private sector are needed to ensure that affordable medicines for today's neglected diseases are developed. Priority action areas include advocating an essential medicines R&D agenda, capacity-building in and technology transfer to developing countries, elaborating an adapted legal and regulatory framework, prioritizing funding for essential drug development and securing availability, accessibility, distribution and rational use of these drugs

    0+ states and collective bands in 228Th studied by the (p,t) reaction

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    The excitation spectra in the deformed nucleus 228Th have been studied by means of the (p,t)-reaction, using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons were measured for about 110 excitations seen in the triton spectra up to 2.5 MeV. Firm 0+ assignments are made for 17 excited states by comparison of experimental angular distributions with the calculated ones using the CHUCK3 code. Assignments up to spin 6+ are made for other states. Sequences of states are selected which can be treated as rotational bands and as multiplets of excitations. Moments of inertia have been derived from these sequences, whose values may be considered as evidence of the two-phonon nature of most 0+ excitations. Experimental data are compared with interacting boson model and quasiparticle-phonon model calculations and with experimental data for 229Pa.Comment: 21 pages, 14 figure

    THE EFFECT OF NON·CONTACT THERAPEUTIC TOUCH ON THE HEALING RATE OF FULL THICKNESS DERMAL WOUNDS

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    The effect of Noncontact Therapeutic Touch (NClD on the rate of surgical wound healing was examined in a double-blind study. Full-thickness dermal wounds were incised on the lateral deltoid region using a skin punch biopsy instrument, on healthy subjects randomly assigned to treatment or control groups. Subjects were blinded both to group assignment and to the true nature of the active treatment modality in order to control placebo and expectation effects. Incisions were dressed with gas-permeable dressings, and wound surface areas were measured on Days 0, 8, and 16 using a direct tracing method and digitization system. Active and control treatments were comprised ofdaily sessions offive minutes of exposure to a hidden Therapeutic Touch practitioner or to sham exposure.Results showed that treated subjects experienced a significant acceleration in the rate of wound healing as compared to non-treated subjects at day8 (Mann-Whitney U; Z =-5.675; n =44; p<.OO1; 2 tailed), and at day 16 (X2 =16.847, df =1; p<.OO1). Statistical comparisons are dominated by the complete healing of 13 of 23 treated subjects vs. O of 21 control subjects by day 16. Placebo effects and the possible influences of suggestion and expectation of healing were eliminated by isolating the subjects from the Therapeutic Touch practitioner, by blinding them to the nature of the therapy during the study, and by the use of an independent experimenter who was blinded to the nature of the therapy. The findings of this study demonstrate, at least, the potential for NCIT in the healing of full-thickness human dermal wounds

    THE EFFECT OF NON·CONTACT THERAPEUTIC TOUCH ON THE HEALING RATE OF FULL THICKNESS DERMAL WOUNDS

    Get PDF
    The effect of Noncontact Therapeutic Touch (NClD on the rate of surgical wound healing was examined in a double-blind study. Full-thickness dermal wounds were incised on the lateral deltoid region using a skin punch biopsy instrument, on healthy subjects randomly assigned to treatment or control groups. Subjects were blinded both to group assignment and to the true nature of the active treatment modality in order to control placebo and expectation effects. Incisions were dressed with gas-permeable dressings, and wound surface areas were measured on Days 0, 8, and 16 using a direct tracing method and digitization system. Active and control treatments were comprised ofdaily sessions offive minutes of exposure to a hidden Therapeutic Touch practitioner or to sham exposure.Results showed that treated subjects experienced a significant acceleration in the rate of wound healing as compared to non-treated subjects at day8 (Mann-Whitney U; Z =-5.675; n =44; p&lt;.OO1; 2 tailed), and at day 16 (X2 =16.847, df =1; p&lt;.OO1). Statistical comparisons are dominated by the complete healing of 13 of 23 treated subjects vs. O of 21 control subjects by day 16. Placebo effects and the possible influences of suggestion and expectation of healing were eliminated by isolating the subjects from the Therapeutic Touch practitioner, by blinding them to the nature of the therapy during the study, and by the use of an independent experimenter who was blinded to the nature of the therapy. The findings of this study demonstrate, at least, the potential for NCIT in the healing of full-thickness human dermal wounds
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