9,059 research outputs found

    Tailoring therapy for heart failure: the pharmacogenomics of adrenergic receptor signaling.

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    Heart failure is one of the leading causes of mortality in Western countries, and ÎČ-blockers are a cornerstone of its treatment. However, the response to these drugs is variable among individuals, which might be explained, at least in part, by genetic differences. Pharmacogenomics is the study of genetic contributions to drug response variability in order to provide evidence for a tailored therapy in an individual patient. Several studies have investigated the pharmacogenomics of the adrenergic receptor system and its role in the context of the use of ÎČ-blockers in treating heart failure. In this review, we will focus on the most significant polymorphisms described in the literature involving adrenergic receptors and adrenergic receptor-related proteins, as well as genetic variations influencing ÎČ-blocker metabolism

    The faintest galaxies

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    We investigate the nature of Ultra Faint dwarf spheroidal galaxies (UF dSphs) in a general cosmological context, simultaneously accounting for various "classical" dSphs and Milky Way (MW) properties, including their Metallicity Distribution Function (MDF). The model successfully reproduces both the observed [Fe/H]-Luminosity relation and the mean MDF of UFs. According to our results UFs are the living fossils of H2-cooling minihaloes formed at z>8.5, i.e. before the end of reionization. They are the oldest and the most dark matter-dominated (M/L > 100) dSphs in the MW system, with a total mass of M = 10^(7-8) Msun. The model allows to interpret the different shape of UFs and classical dSphs MDF, along with the frequency of extremely metal-poor stars in these objects. We discuss the "missing satellites problem" by comparing the UF star formation efficiencies with those derived for minihaloes in the Via Lactea simulation.Comment: To appear in the conference proceeding: "First Stars and Galaxies: Challenges in the Next Decade" . Publisher: American Institute of Physics. Editors: V. Bromm, D. Whalen, N. Yoshid

    Lorentz invariant and supersymmetric interpretation of noncommutative quantum field theory

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    In this paper, using a Hopf-algebraic method, we construct deformed Poincar\'e SUSY algebra in terms of twisted (Hopf) algebra. By adapting this twist deformed super-Poincar\'e algrebra as our fundamental symmetry, we can see the consistency between the algebra and non(anti)commutative relation among (super)coordinates and interpret that symmetry of non(anti)commutative QFT is in fact twisted one. The key point is validity of our new twist element that guarantees non(anti)commutativity of space. It is checked in this paper for N=1 case. We also comment on the possibility of noncommutative central charge coordinate. Finally, because our twist operation does not break the original algebra, we can claim that (twisted) SUSY is not broken in contrast to the string inspired N=1/2\mathcal{N}=1/2 SUSY in N=1 non(anti)commutative superspace.Comment: 15 pages, LaTeX. v3:One section added, typos corrected, to appear in Int. J. Mod. Phys.

    Partitioning a graph into highly connected subgraphs

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    Given k≄1k\ge 1, a kk-proper partition of a graph GG is a partition P{\mathcal P} of V(G)V(G) such that each part PP of P{\mathcal P} induces a kk-connected subgraph of GG. We prove that if GG is a graph of order nn such that ÎŽ(G)≄n\delta(G)\ge \sqrt{n}, then GG has a 22-proper partition with at most n/ÎŽ(G)n/\delta(G) parts. The bounds on the number of parts and the minimum degree are both best possible. We then prove that If GG is a graph of order nn with minimum degree ÎŽ(G)≄c(k−1)n\delta(G)\ge\sqrt{c(k-1)n}, where c=2123180c=\frac{2123}{180}, then GG has a kk-proper partition into at most cnÎŽ(G)\frac{cn}{\delta(G)} parts. This improves a result of Ferrara, Magnant and Wenger [Conditions for Families of Disjoint kk-connected Subgraphs in a Graph, Discrete Math. 313 (2013), 760--764] and both the degree condition and the number of parts are best possible up to the constant cc

    Looking at cosmic near-infrared background radiation anisotropies

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    The cosmic infrared background (CIB) contains emissions accumulated over the entire history of the Universe, including from objects inaccessible to individual telescopic studies. The near-IR (~1-10 mic) part of the CIB, and its fluctuations, reflects emissions from nucleosynthetic sources and gravitationally accreting black holes (BHs). If known galaxies are removed to sufficient depths the source-subtracted CIB fluctuations at near-IR can reveal sources present in the first-stars-era and possibly new stellar populations at more recent times. This review discusses the recent progress in this newly emerging field which identified, with new data and methodology, significant source-subtracted CIB fluctuations substantially in excess of what can be produced by remaining known galaxies. The CIB fluctuations further appear coherent with unresolved cosmic X-ray background (CXB) indicating a very high fraction of BHs among the new sources producing the CIB fluctuations. These observations have led to intensive theoretical efforts to explain the measurements and their properties. While current experimental configurations have limitations in decisively probing these theories, their potentially remarkable implications will be tested in the upcoming CIB measurements with the ESA's Euclid dark energy mission. We describe the goals and methodologies of LIBRAE (Looking at Infrared Background Radiation with Euclid), a NASA-selected project for CIB science with Euclid, which has the potential for transforming the field into a new area of precision cosmology.Comment: Reviews of Modern Physics, to appea

    Generation of the Primordial Magnetic Fields during Cosmological Reionization

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    We investigate the generation of magnetic field by the Biermann battery in cosmological ionization fronts, using new simulations of the reionization of the universe by stars in protogalaxies. Two mechanisms are primarily responsible for magnetogenesis: i) the breakout of I-fronts from protogalaxies, and ii) the propagation of I-fronts through the high density neutral filaments which are part of the cosmic web. The first mechanism is dominant prior to overlapping of ionized regions (z ~ 7), whereas the second continues to operate even after that epoch. However, after overlap the field strength increase is largely due to the gas compression occurring as cosmic structures form. As a consequence, the magnetic field at z ~ 5 closely traces the gas density, and it is highly ordered on megaparsec scales. The mean mass-weighted field strength is B_0 ~ 10^{-19} G in the simulation box. There is a relatively well-defined, nearly linear correlation between B_0 and the baryonic mass of virialized objects, with B_0 ~ 10^{-18} G in the most massive objects (M ~ 10^9 M_sun) in our simulations. This is a lower limit, as lack of numerical resolution prevents us from following small scale dynamical processes which could amplify the field in protogalaxies. Although the field strengths we compute are probably adequate as seed fields for a galactic dynamo, the field is too small to have had significant effects on galaxy formation, on thermal conduction, or on cosmic ray transport in the intergalactic medium. It could, however, be observed in the intergalactic medium through innovative methods based on analysis of gamma-ray burst photon arrival times.Comment: accepted for publication in ApJ. MPEG movies and color versions of figures are available at http://casa.colorado.edu/~gnedin/GALLERY/magfi_p.htm

    On Supergroups with Odd Clifford Parameters and Supersymmetry with Modified Leibniz Rule

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    We investigate supergroups with Grassmann parameters replaced by odd Clifford parameters. The connection with non-anticommutative supersymmetry is discussed. A Berezin-like calculus for odd Clifford variables is introduced. Fermionic covariant derivatives for supergroups with odd Clifford variables are derived. Applications to supersymmetric quantum mechanics are made. Deformations of the original supersymmetric theories are encountered when the fermionic covariant derivatives do not obey the graded Leibniz property. The simplest non-trivial example is given by the N=2 SQM with a real (1,2,1)(1,2,1) multiplet and a cubic potential. The action is real. Depending on the overall sign ("Euclidean" or "Lorentzian") of the deformation, a Bender-Boettcher pseudo-hermitian hamiltonian is encountered when solving the equation of motion of the auxiliary field. A possible connection of our framework with the Drinfeld twist deformation of supersymmetry is pointed out.Comment: Final version to be published in Int. J. Mod. Phys. A; 20 page

    Renormalizability of N=1/2 Wess-Zumino model in superspace

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    In this letter we use the spurion field approach adopted in hep-th/0307099 in order to show that by adding F and F^2 terms to the original lagrangian, the N=1/2 Wess-Zumino model is renormalizable to all orders in perturbation theory. We reformulate in superspace language the proof given in the recent work hep-th/0307165 in terms of component fields.Comment: 8 pages, minor change

    Non-Perturbative Green's Functions in Theories with Extended Superconformal Symmetry

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    The multiplets that occur in four dimensional rigidly supersymmetric theories can be described either by chiral superfields in Minkowski superspace or analytic superfields in harmonic superspace. The superconformal Ward identities for Green's functions of gauge invariant operators of these types are derived. It is shown that there are no chiral superconformal invariants. It is further shown that the Green's functions of analytic operators are severely restricted by the superconformal Ward when analyticity is taken into account.Comment: 17 pages, plain tex. Some conjectures that were in the original paper are clarifed in the light of more recent work to which we give references. See Note added for detail
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