1,101 research outputs found

    Genome sequences of \u3ci\u3eAgropyron mosaic virus\u3c/i\u3e and \u3ci\u3eHordeum mosaic virus \u3c/i\u3esupport reciprocal monophyly of the genera \u3ci\u3ePotyvirus\u3c/i\u3e and \u3ci\u3eRymovirus \u3c/i\u3e in the family \u3ci\u3ePotyviridae\u3c/i\u3e

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    Assignment of mite-transmitted species to the genus Rymovirus (family Potyviridae) has changed several times, and the status of the genus has been questioned. To address this issue, complete genome sequences of the rymoviruses Agropyron mosaic virus (AgMV) and Hordeum mosaic virus (HoMV) were determined. AgMV (9540 nucleotides) and HoMV (9463 nucleotides) each encode a single polyprotein with proteinase cleavage sites demarcating protein products characteristic of monopartite species of the family Potyviridae. Of the described species of Potyviridae, AgMV and HoMV are most closely related to each other (68.5% nucleotide and 71.6% amino acid sequence identity) and equidistant (about 53% nucleotide and about 49% amino acid sequence identity) from a third rymovirus, Ryegrass mosaic virus (RGMV). Phylogenetic analyses by neighbor joining, maximum parsimony, and Bayesian inference each grouped the three Rymovirus species in an exclusive clade distinct from a clade containing 34 species of the genus Potyvirus. Because AgMV, HoMV, and RGMV share a reciprocal monophyletic relationship with species of the genus Potyvirus and are divergent in sequence and type of vector, the genus Rymovirus should be retained as a taxonomic unit within the family Potyviridae

    Three Generations in Type I Compactifications

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    Generalizing the recent work on three-family Type I compactifications, we classify perturbative Type I vacua obtained via compactifying on the T^6/Z_2 X Z_2 X Z_3 orbifold with all possible Wilson lines. In particular, we concentrate on models with gauge groups containing the Standard Model gauge group SU(3)_c X SU(2)_w X U(1)_Y as a subgroup. All of the vacua we obtain contain D5-branes and are non-perturbative from the heterotic viewpoint. The models we discuss have three-chiral families. We study some of their phenomenological properties, and point out non-trivial problems arising in these models in the phenomenological context.Comment: 16 pages, revtex, minor misprints correcte

    Flow characterisation for a validation study in high-speed aerodynamics

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    Validation studies are becoming increasingly relevant when investigating complex flow problems in high-speed aerodynamics. These investigations require calibration of numerical models with accurate data from the physical wind tunnel being studied. This paper presents the characterisation process for a joint experimental-computational study to investigate the streamwise corners of a Mach 2.5 channel flow. As well as checks of flow quality typically performed for phenomenological investigations, additional quantitative tests are conducted. The extra care to obtain high quality data and eliminate any systematic errors reveal useful information about the wind tunnel flow. Further important physical insights are gained from designing and conducting wind tunnel tests in conjunction with numerical simulations. Crucially, the close experimental-computational collaboration enabled the identification of secondary flows in the sidewall boundary-layers; these strongly influence the flow in the corner regions, the target of the validation study

    Precision Timing Measurements of PSR J1012+5307

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    We present results and applications of high precision timing measurements of the millisecond pulsar J1012+5307. Combining our radio observations with results based on optical observations, we derive complete 3-D velocity information for this system. Correcting for Doppler effects, we derive the intrinsic spin parameters of this pulsar and a characteristic age of 8.6 +/- 1.9 Gyr. Our upper limit for the orbital eccentricity of only 8 * 10^-7 (68% C.L.) is the smallest ever measured for a binary system. We demonstrate that this makes the pulsar an ideal laboratory to test certain aspects of alternative theories of gravitation. Our precise measurements suggest deviations from a simple pulsar spin-down timing model, which are consistent with timing noise and the extrapolation of the known behaviour of slowly rotating pulsars.Comment: 9 pages, 6 figure

    Some anisotropic universes in the presence of imperfect fluid coupling with spatial curvature

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    We consider Bianchi VI spacetime, which also can be reduced to Bianchi types VI0-V-III-I. We initially consider the most general form of the energy-momentum tensor which yields anisotropic stress and heat flow. We then derive an energy-momentum tensor that couples with the spatial curvature in a way so as to cancel out the terms that arise due to the spatial curvature in the evolution equations of the Einstein field equations. We obtain exact solutions for the universes indefinetly expanding with constant mean deceleration parameter. The solutions are beriefly discussed for each Bianchi type. The dynamics of the models and fluid are examined briefly, and the models that can approach to isotropy are determined. We conclude that even if the observed universe is almost isotropic, this does not necessarily imply the isotropy of the fluid (e.g., dark energy) affecting the evolution of the universe within the context of general relativity.Comment: 17 pages, no figures; to appear in International Journal of Theoretical Physics; in this version (which is more concise) an equation added, some references updated and adde

    Use of the Generalized Gradient Approximation in Pseudopotential Calculations of Solids

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    We present a study of the equilibrium properties of spsp-bonded solids within the pseudopotential approach, employing recently proposed generalized gradient approximation (GGA) exchange correlation functionals. We analyze the effects of the gradient corrections on the behavior of the pseudopotentials and discuss possible approaches for constructing pseudopotentials self-consistently in the context of gradient corrected functionals. The calculated equilibrium properties of solids using the GGA functionals are compared to the ones obtained through the local density approximation (LDA) and to experimental data. A significant improvement over the LDA results is achieved with the use of the GGA functionals for cohesive energies. For the lattice constant, the same accuracy as in LDA can be obtained when the nonlinear coupling between core and valence electrons introduced by the exchange correlation functionals is properly taken into account. However, GGA functionals give bulk moduli that are too small compared to experiment.Comment: 15 pages, latex, no figure

    Parity Violation in Proton-Proton Scattering

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    Measurements of parity-violating longitudinal analyzing powers (normalized asymmetries) in polarized proton-proton scattering provide a unique window on the interplay between the weak and strong interactions between and within hadrons. Several new proton-proton parity violation experiments are presently either being performed or are being prepared for execution in the near future: at TRIUMF at 221 MeV and 450 MeV and at COSY (Kernforschungsanlage Juelich) at 230 MeV and near 1.3 GeV. These experiments are intended to provide stringent constraints on the set of six effective weak meson-nucleon coupling constants, which characterize the weak interaction between hadrons in the energy domain where meson exchange models provide an appropriate description. The 221 MeV is unique in that it selects a single transition amplitude (3P2-1D2) and consequently constrains the weak meson-nucleon coupling constant h_rho{pp}. The TRIUMF 221 MeV proton-proton parity violation experiment is described in some detail. A preliminary result for the longitudinal analyzing power is Az = (1.1 +/-0.4 +/-0.4) x 10^-7. Further proton-proton parity violation experiments are commented on. The anomaly at 6 GeV/c requires that a new multi-GeV proton-proton parity violation experiment be performed.Comment: 13 Pages LaTeX, 5 PostScript figures, uses espcrc1.sty. Invited talk at QULEN97, International Conference on Quark Lepton Nuclear Physics -- Nonperturbative QCD Hadron Physics & Electroweak Nuclear Processes --, Osaka, Japan May 20--23, 199

    The TELE-DD project on treatment nonadherence in the population with type 2 diabetes and comorbid depression

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    Diabetic patients have increased depression rates, diminished quality of life, and higher death rates due to depression comorbidity or diabetes complications. Treatment adherence (TA) and the maintenance of an adequate and competent self-care are crucial factors to reach optimal glycaemic control and stable quality of life in these patients. In this report, we present the baseline population analyses in phase I of the TELE-DD project, a three-phased population-based study in 23 Health Centres from the Aragonian Health Service Sector II in Zaragoza, Spain. The objectives of the present report are: (1) to determine the point prevalence of T2D and clinical depression comorbidity and treatment nonadherence; (2) to test if HbA1c and LDL-C, as primary DM outcomes, are related to TA in this population; and (3) to test if these DM primary outcomes are associated with TA independently of shared risk factors for DM and depression, and patients’ health behaviours. A population of 7,271 patients with type-2 diabetes and comorbid clinical depression was investigated for inclusion. Individuals with confirmed diagnoses and drug treatment for both illnesses (n = 3340) were included in the current phase I. A point prevalence of 1.9% was found for the T2D-depression comorbidity. The prevalence of patients nonadherent to treatment for these diseases was 35.4%. Multivariate analyses confirmed that lower diabetes duration, increased yearly PCS visits, HbA1c and LDL-C levels were independently related to treatment nonadherence. These findings informed the development of a telephonic monitoring platform for treatment of nonadherence for people with diabetes and comorbid depression and further trial, cost-effectiveness, and prognostic studies (phases II and III)

    NF-κB and IκBα are found in the mitochondria. Evidence for regulation of mitochondrial gene expression by NF-κB

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    The transcription factor NF-κB has been shown to be predominantly cytoplasmically localized in the absence of an inductive signal. Stimulation of cells with inflammatory cytokines such as tumor necrosis factor α or interleukin-1 induces the degradation of IκB, the inhibitor of NF-κB, allowing nuclear accumulation of NF-κB and regulation of specific gene expression. The degradation of IκB is controlled initially by phosphorylation induced by the IκB kinase, which leads to ubiquitination and subsequent proteolysis of the inhibitor by the proteasome. We report here that NF-κB and IκBα (but not IκBβ) are also localized in the mitochondria. Stimulation of cells with tumor necrosis factor α leads to the phosphorylation of mitochondrial IκBα and its subsequent degradation by a nonproteasome-dependent pathway. Interestingly, expression of the mitochondrially encoded cytochrome c oxidase III and cytochrome b mRNAs were reduced by cytokine treatment of cells. Inhibition of activation of mitochondrial NF-κB by expression of the superrepressor form of IκBα inhibited the loss of expression of both cytochrome c oxidase III and cytochrome b mRNA. These data indicate that the NF-κB regulatory pathway exists in mitochondria and that NF-κB can negatively regulate mitochondrial mRNA expression

    A Green's function approach to transmission of massless Dirac fermions in graphene through an array of random scatterers

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    We consider the transmission of massless Dirac fermions through an array of short range scatterers which are modeled as randomly positioned δ\delta- function like potentials along the x-axis. We particularly discuss the interplay between disorder-induced localization that is the hallmark of a non-relativistic system and two important properties of such massless Dirac fermions, namely, complete transmission at normal incidence and periodic dependence of transmission coefficient on the strength of the barrier that leads to a periodic resonant transmission. This leads to two different types of conductance behavior as a function of the system size at the resonant and the off-resonance strengths of the delta function potential. We explain this behavior of the conductance in terms of the transmission through a pair of such barriers using a Green's function based approach. The method helps to understand such disordered transport in terms of well known optical phenomena such as Fabry Perot resonances.Comment: 22 double spaced single column pages. 15 .eps figure
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