1,425 research outputs found

    Two real parton contributions to non-singlet kernels for exclusive QCD DGLAP evolution

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    Results for the two real parton differential distributions needed for implementing a next-to-leading order (NLO) parton shower Monte Carlo are presented. They are also integrated over the phase space in order to provide solid numerical control of the MC codes and for the discussion of the differences between the standard MSˉ\bar{MS} factorization and Monte Carlo implementation at the level of inclusive NLO evolution kernels. Presented results cover the class of non-singlet diagrams entering into NLO kernels. The classic work of Curci-Furmanski-Pertonzio was used as a guide in the calculations.Comment: 34 pages, 3 figure

    Numerical Modeling of Fluid Flow in Solid Tumors

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    A mathematical model of interstitial fluid flow is developed, based on the application of the governing equations for fluid flow, i.e., the conservation laws for mass and momentum, to physiological systems containing solid tumors. The discretized form of the governing equations, with appropriate boundary conditions, is developed for a predefined tumor geometry. The interstitial fluid pressure and velocity are calculated using a numerical method, element based finite volume. Simulations of interstitial fluid transport in a homogeneous solid tumor demonstrate that, in a uniformly perfused tumor, i.e., one with no necrotic region, because of the interstitial pressure distribution, the distribution of drug particles is non-uniform. Pressure distribution for different values of necrotic radii is examined and two new parameters, the critical tumor radius and critical necrotic radius, are defined. Simulation results show that: 1) tumor radii have a critical size. Below this size, the maximum interstitial fluid pressure is less than what is generally considered to be effective pressure (a parameter determined by vascular pressure, plasma osmotic pressure, and interstitial osmotic pressure). Above this size, the maximum interstitial fluid pressure is equal to effective pressure. As a consequence, drugs transport to the center of smaller tumors is much easier than transport to the center of a tumor whose radius is greater than the critical tumor radius; 2) there is a critical necrotic radius, below which the interstitial fluid pressure at the tumor center is at its maximum value. If the tumor radius is greater than the critical tumor radius, this maximum pressure is equal to effective pressure. Above this critical necrotic radius, the interstitial fluid pressure at the tumor center is below effective pressure. In specific ranges of these critical sizes, drug amount and therefore therapeutic effects are higher because the opposing force, interstitial fluid pressure, is low in these ranges

    Quantum gravity effects on statistics and compact star configurations

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    The thermodynamics of classical and quantum ideal gases based on the Generalized uncertainty principle (GUP) are investigated. At low temperatures, we calculate corrections to the energy and entropy. The equations of state receive small modifications. We study a system comprised of a zero temperature ultra-relativistic Fermi gas. It turns out that at low Fermi energy εF\varepsilon_F, the degenerate pressure and energy are lifted. The Chandrasekhar limit receives a small positive correction. We discuss the applications on configurations of compact stars. As εF\varepsilon_F increases, the radius, total number of fermions and mass first reach their nonvanishing minima and then diverge. Beyond a critical Fermi energy, the radius of a compact star becomes smaller than the Schwarzschild one. The stability of the configurations is also addressed. We find that beyond another critical value of the Fermi energy, the configurations are stable. At large radius, the increment of the degenerate pressure is accelerated at a rate proportional to the radius.Comment: V2. discussions on the stability of star configurations added, 17 pages, 2 figures, typos corrected, version to appear in JHE

    Bidirectional lipid droplet velocities are controlled by differential binding strengths of HCV Core DII protein

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    Host cell lipid droplets (LD) are essential in the hepatitis C virus (HCV) life cycle and are targeted by the viral capsid core protein. Core-coated LDs accumulate in the perinuclear region and facilitate viral particle assembly, but it is unclear how mobility of these LDs is directed by core. Herein we used two-photon fluorescence, differential interference contrast imaging, and coherent anti-Stokes Raman scattering microscopies, to reveal novel core-mediated changes to LD dynamics. Expression of core protein’s lipid binding domain II (DII-core) induced slower LD speeds, but did not affect directionality of movement on microtubules. Modulating the LD binding strength of DII-core further impacted LD mobility, revealing the temporal effects of LD-bound DII-core. These results for DII-core coated LDs support a model for core-mediated LD localization that involves core slowing down the rate of movement of LDs until localization at the perinuclear region is accomplished where LD movement ceases. The guided localization of LDs by HCV core protein not only is essential to the viral life cycle but also poses an interesting target for the development of antiviral strategies against HCV

    Feasibility and Coverage of Implementing Intermittent Preventive Treatment of Malaria in Pregnant women Contacting Private or Public Clinics in Tanzania: Experience-based Viewpoints of Health Managers in Mkuranga and Mufindi districts.

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    Evidence on healthcare managers' experience on operational feasibility of malaria intermittent preventive treatment for malaria during pregnancy (IPTp) using sulphadoxine-pyrimethamine (SP) in Africa is systematically inadequate. This paper elucidates the perspectives of District Council Health Management Team (CHMT)s regarding the feasibility of IPTp with SP strategy, including its acceptability and ability of district health care systems to cope with the contemporary and potential challenges. The study was conducted in Mkuranga and Mufindi districts. Data were collected between November 2005 and December 2007, involving focus group discussion (FGD) with Mufindi CHMT and in-depth interviews were conducted with few CHMT members in Mkuranga where it was difficult to summon all members for FGD. Participants in both districts acknowledged the IPTp strategy, considering the seriousness of malaria in pregnancy problem; government allocation of funds to support healthcare staff training programmes in focused antenatal care (fANC) issues, procuring essential drugs distributed to districts, staff remuneration, distribution of fANC guidelines, and administrative activities performed by CHMTs. The identified weaknesses include late arrival of funds from central level weakening CHMT's performance in health supervision, organising outreach clinics, distributing essential supplies, and delivery of IPTp services. Participants anticipated the public losing confidence in SP for IPTp after government announced artemither-lumefantrine (ALu) as the new first-line drug for uncomplicated malaria replacing SP. Role of private healthcare staff in IPTp services was acknowledged cautiously because CHMTs rarely supplied private clinics with SP for free delivery in fear that clients would be required to pay for the SP contrary to government policy. In Mufindi, the District Council showed a strong political support by supplementing ANC clinics with bottled water; in Mkuranga such support was not experienced. A combination of health facility understaffing, water scarcity and staff non-adherence to directly observed therapy instructions forced healthcare staff to allow clients to take SP at home. Need for investigating in improving adherence to IPTp administration was emphasised. High acceptability of the IPTp strategy at district level is meaningless unless necessary support is assured in terms of number, skills and motivation of caregivers and availability of essential supplies

    Sub-Planckian black holes and the Generalized Uncertainty Principle

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    The Black Hole Uncertainty Principle correspondence suggests that there could exist black holes with mass beneath the Planck scale but radius of order the Compton scale rather than Schwarzschild scale. We present a modified, self-dual Schwarzschild-like metric that reproduces desirable aspects of a variety of disparate models in the sub-Planckian limit, while remaining Schwarzschild in the large mass limit. The self-dual nature of this solution under MM1M \leftrightarrow M^{-1} naturally implies a Generalized Uncertainty Principle with the linear form Δx1Δp+Δp\Delta x \sim \frac{1}{\Delta p} + \Delta p. We also demonstrate a natural dimensional reduction feature, in that the gravitational radius and thermodynamics of sub-Planckian objects resemble that of (1+1)(1+1)-D gravity. The temperature of sub-Planckian black holes scales as MM rather than M1M^{-1} but the evaporation of those smaller than 103610^{-36}g is suppressed by the cosmic background radiation. This suggests that relics of this mass could provide the dark matter.Comment: 12 pages, 9 figures, version published in J. High En. Phy

    Genome Majority Vote Improves Gene Predictions

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    Recent studies have noted extensive inconsistencies in gene start sites among orthologous genes in related microbial genomes. Here we provide the first documented evidence that imposing gene start consistency improves the accuracy of gene start-site prediction. We applied an algorithm using a genome majority vote (GMV) scheme to increase the consistency of gene starts among orthologs. We used a set of validated Escherichia coli genes as a standard to quantify accuracy. Results showed that the GMV algorithm can correct hundreds of gene prediction errors in sets of five or ten genomes while introducing few errors. Using a conservative calculation, we project that GMV would resolve many inconsistencies and errors in publicly available microbial gene maps. Our simple and logical solution provides a notable advance toward accurate gene maps

    Gross-Neveu Models, Nonlinear Dirac Equations, Surfaces and Strings

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    Recent studies of the thermodynamic phase diagrams of the Gross-Neveu model (GN2), and its chiral cousin, the NJL2 model, have shown that there are phases with inhomogeneous crystalline condensates. These (static) condensates can be found analytically because the relevant Hartree-Fock and gap equations can be reduced to the nonlinear Schr\"odinger equation, whose deformations are governed by the mKdV and AKNS integrable hierarchies, respectively. Recently, Thies et al have shown that time-dependent Hartree-Fock solutions describing baryon scattering in the massless GN2 model satisfy the Sinh-Gordon equation, and can be mapped directly to classical string solutions in AdS3. Here we propose a geometric perspective for this result, based on the generalized Weierstrass spinor representation for the embedding of 2d surfaces into 3d spaces, which explains why these well-known integrable systems underlie these various Gross-Neveu gap equations, and why there should be a connection to classical string theory solutions. This geometric viewpoint may be useful for higher dimensional models, where the relevant integrable hierarchies include the Davey-Stewartson and Novikov-Veselov systems.Comment: 27 pages, 1 figur

    Measurement of the charm structure function F_{2,c)^{γ} of the photon at LEP

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    The production of charm quarks is studied in deep-inelastic electron–photon scattering using data recorded by the OPAL detector at LEP at nominal e⁺e⁻ centre-of-mass energies from 183 to 209 GeV. The charm quarks have been identified by full reconstruction of charged D* mesons using their decays into D⁰π with the D⁰ observed in two decay modes with charged particle final states, Kπ and Kπππ. The cross-section σ^{D*} for production of charged D* in the reaction e⁺e⁻→e⁺e⁻D*Χ is measured in a restricted kinematical region using two bins in Bjorken x, 0.00140.1 the perturbative QCD calculation at next-to-leading order agrees perfectly with the measured cross-section. For x<0.1 the measured cross-section is 43.8±14.3±6.3±2.8 pb with a next-to-leading order prediction of 17.0⁺²·⁹_₂.₃ pb
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