693 research outputs found

    Decay of High-Energy Astrophysical Neutrinos

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    Existing limits on the non-radiative decay of one neutrino to another plus a massless particle (e.g., a singlet Majoron) are very weak. The best limits on the lifetime to mass ratio come from solar neutrino observations, and are \tau/m \agt 10^{-4} s/eV for the relevant mass eigenstate(s). For lifetimes even several orders of magnitude longer, high-energy neutrinos from distant astrophysical sources would decay. This would strongly alter the flavor ratios from the ϕνe:ϕνμ:ϕντ=1:1:1\phi_{\nu_e}:\phi_{\nu_{\mu}}:\phi_{\nu_{\tau}} = 1:1:1 expected from oscillations alone, and should be readily visible in the near future in detectors such as IceCube.Comment: 4 pages, 1 figure. References added. Version to appear in PR

    HexPak and GradPak: variable-pitch dual-head IFUs for the WIYN 3.5m Telescope Bench Spectrograph

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    We describe the design, construction, and expected performance of two new fiber integral field units (IFUs) --- HexPak and GradPak --- for the WIYN 3.5m Telescope Nasmyth focus and Bench Spectrograph. These are the first IFUs to provide formatted fiber integral field spectroscopy with simultaneous sampling of varying angular scales. HexPak and GradPak are in a single cable with a dual-head design, permitting easy switching between the two different IFU heads on the telescope without changing the spectrograph feed: the two heads feed a variable-width double-slit. Each IFU head is comprised of a fixed arrangement of fibers with a range of fiber diameters. The layout and diameters of the fibers within each array are scientifically-driven for observations of galaxies: HexPak is designed to observe face-on spiral or spheroidal galaxies while GradPak is optimized for edge-on studies of galaxy disks. HexPak is a hexagonal array of 2.9 arcsec fibers subtending a 40.9 arcsec diameter, with a high-resolution circular core of 0.94 arcsec fibers subtending 6 arcsec diameter. GradPak is a 39 by 55 arcsec rectangular array with rows of fibers of increasing diameter from angular scales of 1.9 arcsec to 5.6 arcsec across the array. The variable pitch of these IFU heads allows for adequate sampling of light profile gradients while maintaining the photon limit at different scales.Comment: 10 pages, 4 figures, presented at SPIE, Astronomical Telescopes and Instrumentation, 1 - 6 July 2012, Amsterdam, Netherland

    The Higgs Sector and CoGeNT/DAMA-Like Dark Matter in Supersymmetric Models

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    Recent data from CoGeNT and DAMA are roughly consistent with a very light dark matter particle with m\sim 4-10\gev and spin-independent cross section of order \sigma_{SI} \sim (1-3)\times 10^{-4}\pb. An important question is whether these observations are compatible with supersymmetric models obeying Ωh2∼0.11\Omega h^2\sim 0.11 without violating existing collider constraints and precision measurements. In this talk, I review the fact the the Minimal Supersymmetric Model allows insufficient flexibility to achieve such compatibility, basically because of the highly constrained nature of the MSSM Higgs sector in relation to LEP limits on Higgs bosons. I then outline the manner in which the more flexible Higgs sectors of the Next-to-Minimal Supersymmetric Model and an Extended Next-to-Minimal Supersymmetric Model allow large σSI\sigma_{SI} and Ωh2∼0.11\Omega h^2\sim 0.11 at low LSP mass without violating LEP, Tevatron, BaBar and other experimental limits. The relationship of the required Higgs sectors to the NMSSM "ideal-Higgs" scenarios is discussed.Comment: 11 pages, 3 figures. To appear in Proceedings of PASCOS 2010. The paper is a compilation of talks given at: PASCOS 2010, ORSAY Workshop on "Higgs Hunting", and SLAC Workshop on "Topologies for Early LHC Searches

    Optimisation of concentration of <i>Undaria pinnarifida</i> (Wakame) and <i>Himathalia elongate</i> (Sea Spaghetti) varieties to effect digestibility, texture and consumer attribute preference

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    In this study, seaweed concertation in a model system (cracker) was investigated to better understand addition of seaweed on starch modulation, texture, and consumer attribute detection. Temporal dominance of sensations (TDS) showed that seaweed concentrations over 15% had a dominant attribute of fishy for both Wakame and Sea Spaghetti varieties, whereas for both, Crunchy was observed for the 5% and 10% crackers. This corralled well with the texture analysis where crackers fortified with both seaweeds at 5% and 10% have a harder texture, with lower fracturability compared to higher concentrated seaweed crackers. The fracturability levels within the 15% and 20% crackers were comparable to the no substitution controls. In vitro digestion indicated that glucose was liberated immediately after initiation, with both seaweed systems reaching plateau by 4 minutes. In this study it was observed that seaweed variety affected starch digestibility, with wakame seaweed inhibiting starch digestion.</p

    Working with simple machines

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    A set of examples is provided that illustrate the use of work as applied to simple machines. The ramp, pulley, lever and hydraulic press are common experiences in the life of a student and their theoretical analysis therefore makes the abstract concept of work more real. The mechanical advantage of each of these systems is also discussed so that students can evaluate their usefulness as machines.Comment: 9 pages, 4 figure

    Prostatic trypsin-like kallikrein-related peptidases (KLKs) and other prostate-expressed tryptic proteinases as regulators of signalling via proteinase-activated receptors (PARs)

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    The prostate is a site of high expression of serine proteinases including members of the kallikrein-related peptidase (KLK) family, as well as other secreted and membrane-anchored serine proteinases. It has been known for some time that members of this enzyme family elicit cellular responses by acting directly on cells. More recently, it has been recognised that for serine proteinases with specificity for cleavage after arginine and lysine residues (trypsin-like or tryptic enzymes) these cellular responses are often mediated by cleavage of members of the proteinase-activated receptor (PAR) family - a four member sub-family of G protein-coupled receptors. Here, we review the expression of PARs in prostate, the ability of prostatic trypsin-like KLKs and other prostate-expressed tryptic enzymes to cleave PARs, as well as the prostate cancer-associated consequences of PAR activation. In addition, we explore the dysregulation of trypsin-like serine proteinase activity through the loss of normal inhibitory mechanisms and potential interactions between these dysregulated enzymes leading to aberrant PAR activation, intracellular signalling and cancer-promoting cellular changes

    Z(2)-Singlino Dark Matter in a Portal-Like Extension of the Minimal Supersymmetric Standard Model.

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    We propose a Z2-stabilized singlino () as a dark matter candidate in extended and R-parity violating versions of the supersymmetric standard model. interacts with visible matter via a heavy messenger field S, which results in a supersymmetric version of the Higgs portal interaction. The relic abundance of can account for cold dark matter if the messenger mass satisfies GeV. Our model can be implemented in many realistic supersymmetric models such as the next-to-minimal supersymmetric (SUSY) standard model and nearly minimal SUSY standard model
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