2,617 research outputs found

    Charge and momentum transfer in supercooled melts: Why should their relaxation times differ?

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    The steady state values of the viscosity and the intrinsic ionic-conductivity of quenched melts are computed, in terms of independently measurable quantities. The frequency dependence of the ac dielectric response is estimated. The discrepancy between the corresponding characteristic relaxation times is only apparent; it does not imply distinct mechanisms, but stems from the intrinsic barrier distribution for α\alpha-relaxation in supercooled fluids and glasses. This type of intrinsic ``decoupling'' is argued not to exceed four orders in magnitude, for known glassformers. We explain the origin of the discrepancy between the stretching exponent β\beta, as extracted from ϵ(ω)\epsilon(\omega) and the dielectric modulus data. The actual width of the barrier distribution always grows with lowering the temperature. The contrary is an artifact of the large contribution of the dc-conductivity component to the modulus data. The methodology allows one to single out other contributions to the conductivity, as in ``superionic'' liquids or when charge carriers are delocalized, implying that in those systems, charge transfer does not require structural reconfiguration.Comment: submitted to J Chem Phy

    Intestinal transplantation under tacrolimus monotherapy after perioperative lymphoid depletion with rabbit anti-thymocyte globulin (thymoglobulin®)

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    Modifications in the timing and dosage of immunosuppression can ameliorate the morbidity and mortality that has prevented widespread use of intestinal transplantation (ITx) in children. Thirty-six patients receiving ITx, aged 5 months to 20 years were given 2-3 mg(kg of rabbit anti-thymocyte globulin (rATG, thymoglobulin®) just before ITx, and 2-3 mg(kg post-operatively (total 5 mg(kg). Twice daily doses of tacrolimus (TAC) were begun enterally within 24 h after graft reperfusion with reduction of dose quantity or frequency after 3 months. Prednisone or other agents were given to treat breakthrough rejection. After 8-28 months follow-up (mean 15.8 ± 5.3), 1- and 2-year patient and graft survival is 100% and 94%, respectively. Despite a 44% incidence of acute rejection in the first month, 16 of the 34 (47%) survivors are on TAC (n = 14) or sirolimus (n = 2) monotherapy; 15 receive TAC plus low dose prednisone; one each receive TAC plus sirolimus, TAC plus azathioprine and TAC plus sirolimus and prednisone. There was a low incidence of immunosuppression-related complications. This strategy of immunosuppression minimized maintenance TAC exposure, facilitated the long-term control of rejection, decreased the incidence of opportunistic infections, and resulted in a high rate of patient and graft survival. Copyright © Blackwell Munksgaard 2005

    Mercapturate Pathway in the Tubulocentric Perspective of Diabetic Kidney Disease

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    BACKGROUND: The recent growing evidence that the proximal tubule underlies the early pathogenesis of diabetic kidney disease (DKD) is unveiling novel and promising perspectives. This pathophysiological concept links tubulointerstitial oxidative stress, inflammation, hypoxia, and fibrosis with the progression of DKD. In this new angle for DKD, the prevailing molecular mechanisms on proximal tubular cells emerge as an innovative opportunity for prevention and management of DKD as well as to improve diabetic dysmetabolism. SUMMARY: The mercapturate pathway (MAP) is a classical metabolic detoxification route for xenobiotics that is emerging as an integrative circuitry detrimental to resolve tubular inflammation caused by endogenous electrophilic species. Herein we review why and how it might underlie DKD. Key Messages: MAP is a hallmark of proximal tubular cell function, and cysteine-S-conjugates might represent targets for early intervention in DKD. Moreover, the biomonitoring of urinary mercapturates from metabolic inflammation products might be relevant for the implementation of preventive/management strategies in DKD.info:eu-repo/semantics/publishedVersio

    Kinetic description of particle interaction with a gravitational wave

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    The interaction of charged particles, moving in a uniform magnetic field, with a plane-polarized gravitational wave is considered using the Fokker-Planck- Kolmogorov (FPK) approach. By using a stochasticity criterion, we determine the exact locations in phase space, where resonance overlapping occurs. We investigate the diffusion of orbits around each primary resonance of order (m) by deriving general analytical expressions for an effective diffusion coeficient. A solution to the corresponding diffusion equation (Fokker-Planck equation) for the static case is found. Numerical integration of the full equations of motion and subsequent calculation of the diffusion coefficient verifies the analytical results.Comment: LaTeX file, 15 page

    Universal Parametric Correlations of Eigenvalues of Random Matrix Ensemble

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    Eigenvalue correlations of random matrix ensembles as a function of an external perturbation are investigated vis the Dyson Brownian Motion Model in the situation where the level density has a hard edge singularity. By solving a linearized hydrodynamical equation, a universal dependence of the density-density correlator on the external field is found. As an application we obtain a formula for the variance of linear statistics with the parametric dependence exhibited as a Laplace transform.Comment: 23 pages, late

    Second cohomology for finite groups of Lie type

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    Let GG be a simple, simply-connected algebraic group defined over Fp\mathbb{F}_p. Given a power q=prq = p^r of pp, let G(Fq)GG(\mathbb{F}_q) \subset G be the subgroup of Fq\mathbb{F}_q-rational points. Let L(λ)L(\lambda) be the simple rational GG-module of highest weight λ\lambda. In this paper we establish sufficient criteria for the restriction map in second cohomology H2(G,L(λ))H2(G(Fq),L(λ))H^2(G,L(\lambda)) \rightarrow H^2(G(\mathbb{F}_q),L(\lambda)) to be an isomorphism. In particular, the restriction map is an isomorphism under very mild conditions on pp and qq provided λ\lambda is less than or equal to a fundamental dominant weight. Even when the restriction map is not an isomorphism, we are often able to describe H2(G(Fq),L(λ))H^2(G(\mathbb{F}_q),L(\lambda)) in terms of rational cohomology for GG. We apply our techniques to compute H2(G(Fq),L(λ))H^2(G(\mathbb{F}_q),L(\lambda)) in a wide range of cases, and obtain new examples of nonzero second cohomology for finite groups of Lie type.Comment: 29 pages, GAP code included as an ancillary file. Rewritten to include the adjoint representation in types An, B2, and Cn. Corrections made to Theorem 3.1.3 and subsequent dependent results in Sections 3-4. Additional minor corrections and improvements also implemente

    Arborização de pastagens: benefícios e limitações.

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    Este trabalho tem como objetivos: discorrer sobre a arborização de pastagens em termos conceituais e em relação aos seus principais benefícios; descrever as principais características das espécies arbóreas que devem ser consideradas no planejamento da implantação de sistemas silvipastoris e considerar as principais limitações para implantação e uso desses sistemas.bitstream/item/214152/1/cpafro-18426-doc-164.pd
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