1,466 research outputs found

    Spiny Lobster Mariculture in the State of Florida

    Get PDF
    The purpose of this paper is to introduce the reader to the Florida spiny lobster, Panuluris argus; to show the economic potential for the mariculture of this species by exposing value and size of the U. S. spiny lobster market; to present Florida’s legal provisions for mariculture and how spiny lobster farming would be acceptable; to indicate the biological considerations for the rearing of spiny lobster larva and postlarva; and to introduce a general plan for the mariculture of spiny lobster, that considers the legal provisions of leasing wetlands in Florida and incorporates the biological considerations of spiny lobster

    Lensing in an interior Kottler solution

    Full text link
    We derive the interior Kottler solution of the incompressible fluid and show that the bending of light in this solution does depend on the cosmological constant.Comment: The inner Kottler solution derived and used in this paper is not new. Corresponding references to Stuchlik (2000) and Boehmer (2003) are added. Also added: a numerical example and a figure. This is the version accepted by Gen. Rel. Grav. However it includes a short passage that an anonymous referee had me suppress

    Very special relativity as relativity of dark matter: the Elko connection

    Get PDF
    In the very special relativity (VSR) proposal by Cohen and Glashow, it was pointed out that invariance under HOM(2) is both necessary and sufficient to explain the null result of the Michelson-Morely experiment. It is the quantum field theoretic demand of locality, or the requirement of P, T, CP, or CT invariance, that makes invariance under the Lorentz group a necessity. Originally it was conjectured that VSR operates at the Planck scale; we propose that the natural arena for VSR is at energies similar to the standard model, but in the dark sector. To this end we provide an ab initio spinor representation invariant under the SIM(2) avatar of VSR and construct a mass dimension one fermionic quantum field of spin one half. This field turns out to be a very close sibling of Elko and it exhibits the same striking property of intrinsic darkness with respect to the standard model fields. In the new construct, the tension between Elko and Lorentz symmetries is fully resolved. We thus entertain the possibility that the symmetries underlying the standard model matter and gauge fields are those of Lorentz, while the event space underlying the dark matter and the dark gauge fields supports the algebraic structure underlying VSR.Comment: 19 pages. Section 5 is new. Published version (modulo a footnote, and a corrected typo

    Sheared-flow induced confinement transition in a linear magnetized plasma

    Get PDF
    A magnetized plasma cylinder (12 cm in diameter) is induced by an annular shape obstacle at the Large Plasma Device [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)]. Sheared azimuthal flow is driven at the edge of the plasma cylinder through edge biasing. Strong fluctuations of density and potential (δn/n~eδφ/kTe~0.5) are observed at the plasma edge, accompanied by a large density gradient (Ln=∣∣∇lnn∣∣−1~2cm) and shearing rate (γ~300kHz). Edge turbulence and cross-field transport are modified by changing the bias voltage (Vbias) on the obstacle and the axial magnetic field (Bz) strength. In cases with low Vbias and large Bz, improved plasma confinement is observed, along with steeper edge density gradients. The radially sheared flow induced by E×B drift dramatically changes the cross-phase between density and potential fluctuations, which causes the wave-induced particle flux to reverse its direction across the shear layer. In cases with higher bias voltage or smaller Bz, large radial transport and rapid depletion of the central plasma density are observed. Two-dimensional cross-correlation measurement shows that a mode with azimuthal mode number m=1 and large radial correlation length dominates the outward transport in these cases. Linear analysis based on a two-fluid Braginskii model suggests that the fluctuations are driven by both density gradient (drift wave like) and flow shear (Kelvin-Helmholtz like) at the plasma edge

    Oxygen saturation targets for children with respiratory distress:a systematic review

    Get PDF
    BACKGROUND: In children with respiratory distress, supplemental oxygen is indicated at peripheral oxygen saturation ( S pO 2 ) thresholds of 90-94%. However, these thresholds are poorly studied. We conducted a systematic review to summarise the existing evidence for S pO 2 thresholds in children with respiratory distress. METHODS: Electronic databases and registries were searched for original articles published from 1 January 2010 to 7 January 2022 comparing two or more S pO 2 thresholds in children with respiratory distress. Primary outcomes were safety, including mortality, neurocognitive outcomes and readmissions, and effectiveness, including admission rate and length of hospital stay. Methodological appraisal was performed using the Cochrane Risk of Bias 2 (RoB-2) or Risk of Bias in Non-Randomized Studies - of Interventions (ROBINS-I) tools. Results were narratively synthesised. RESULTS: We retrieved 3384 results; seven studies were included. Lower thresholds ranged from 80% to 92% and were compared with higher thresholds ranging from 92% to 94%. Studies were highly heterogeneous in setting, design, population and outcomes. Risk of bias varied from low to high. Lower S pO 2 thresholds had equivalent mortality, neurocognitive outcomes and readmissions or re-attendance to healthcare to higher thresholds. Lower S pO 2 thresholds showed a significant decrease in admission rates by up to 40% and shortened hospitalisation duration by 10-18 h. CONCLUSIONS: The current S pO 2 thresholds of 90-94% in children with respiratory distress may be too high, which could lead to unnecessary hospitalisations and prolonged hospitalisation duration. S pO 2 thresholds as low as 88% are potentially safe in children with respiratory distress and may reduce hospitalisation rates and length of stay. However, high-quality evidence is needed to support this. </p

    The Eδ enhancer controls the generation of CD4−CD8− αβTCR-expressing T cells that can give rise to different lineages of αβ T cells

    Get PDF
    It is well established that the pre–T cell receptor for antigen (TCR) is responsible for efficient expansion and differentiation of thymocytes with productive TCRβ rearrangements. However, Ptcra- as well as Tcra-targeting experiments have suggested that the early expression of Tcra in CD4−CD8− cells can partially rescue the development of αβ CD4+CD8+ cells in Ptcra-deficient mice. In this study, we show that the TCR Eδ but not Eα enhancer function is required for the cell surface expression of αβTCR on immature CD4−CD8− T cell precursors, which play a crucial role in promoting αβ T cell development in the absence of pre-TCR. Thus, αβTCR expression by CD4−CD8− thymocytes not only represents a transgenic artifact but occurs under physiological conditions

    Minimum mass of galaxies from BEC or scalar field dark matter

    Full text link
    Many problems of cold dark matter models such as the cusp problem and the missing satellite problem can be alleviated, if galactic halo dark matter particles are ultra-light scalar particles and in Bose-Einstein condensate (BEC), thanks to a characteristic length scale of the particles. We show that this finite length scale of the dark matter can also explain the recently observed common central mass of the Milky Way satellites (107M\sim 10^7 M_\odot) independent of their luminosity, if the mass of the dark matter particle is about 1022eV10^{-22} eV.Comment: 10 pages, 1 figure, accepted in JCA

    Covariant gravitational dynamics in 3+1+1 dimensions

    Get PDF
    We develop a 3+1+1 covariant formalism with cosmological and astrophysical applications. First we give the evolution and constraint equations both on the brane and off-brane in terms of 3-space covariant kinematical, gravito-electro-magnetic (Weyl) and matter variables. We discuss the junction conditions across the brane in terms of the new variables. Then we establish a closure condition for the equations on the brane. We also establish the connection of this formalism with isotropic and anisotropic cosmological brane-worlds. Finally we derive a new brane solution in the framework of our formalism: the tidal charged Taub-NUT-(A)dS brane, which obeys the closure condition.Comment: 35 pages 1 fig; significantly expanded with (a) new closure condition on the brane, (b) discussion of anisotropic brane-worlds, (c) stationary vacuum space-times with local rotational symmetry including (d) a new tidal charged Taub-NUT-(A)dS brane solution; published version
    corecore