3,824 research outputs found

    Could CuB be the site of redox linkage in cytochrome c oxidase?

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    This paper explores the proton pumping function of cytochrome c oxidase [ferrocytochrome-c:oxygen oxidoreductase (EC 1.9.3.1)] based upon redox linkage at the "high-potential" CU(B) center. A model is proposed that is derived from a redox-linked ligand exchange mechanism previously described for the Cu(A) site. Qualitative analysis of this mechanism indicates that such a mechanism is feasible. However, the relatively short distance between Cu(B) and cytochrome a3 implies that the uncoupling electron transfers are quite facile. In addition, the position of the Cu(B) center with respect to the inner mitochondrial membrane argues against redox linkage at the Cu(B) site

    Unstructured Grid Dynamical Modeling of Planetary Atmospheres using planetMPAS: The Influence of the Rigid Lid, Computational Efficiency, and Examples of Martian and Jovian Application

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    We present a new planetary global circulation model, planetMPAS, based on the state-of-the-art NCAR MPAS General Circulation Model. Taking advantage of the cross compatibility between WRF and MPAS, planetMPAS includes most of the planetWRF physics parameterization schemes for terrestrial planets such as Mars and Titan. PlanetMPAS also includes a set of physics that represents radiative transfer, dry convection, moist convection and its associated microphysics for the Jovian atmosphere. We demonstrate that, despite the rigid-lid approximation, planetMPAS is suitable to simulate the climate systems in Martian and Jovian atmospheres with potential application to slow-rotating planets such as Titan. Simulations using planetMPAS show that the new model can reproduce many aspects of the observed features on Mars and Jupiter, such as the seasonal CO2 cycle, polar argon enrichment, zonal mean temperature, and qualitative dust opacity on Mars, as well as the equatorial superrotation and banded zonal wind patterns on Jupiter.Comment: Manuscript has 61 pages, 20 figures, 2 tables, submitted to Planetary and Space Scienc

    Direct Numerical Simulation Of Hypersonic Turbulent Boundary Layers. Part 2. Effect Of Wall Temperature

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    In this paper, we perform direct numerical simulation (DNS) of turbulent boundary layers at Mach 5 with the ratio of wall-to-edge temperature T w/T ℘ from 1.0 to 5.4 (Cases M5T1 to M5T5). The influence of wall cooling on Morkovin\u27s scaling, Walz\u27s equation, the standard and modified strong Reynolds analogies, turbulent kinetic energy budgets, compressibility effects and near-wall coherent structures is assessed. We find that many of the scaling relations used to express adiabatic compressible boundary-layer statistics in terms of incompressible boundary layers also hold for non-adiabatic cases. Compressibility effects are enhanced by wall cooling but remain insignificant, and the turbulence dissipation remains primarily solenoidal. Moreover, the variation of near-wall streaks, iso-surface of the swirl strength and hairpin packets with wall temperature demonstrates that cooling the wall increases the coherency of turbulent structures. We present the mechanism by which wall cooling enhances the coherence of turbulence structures, and we provide an explanation of why this mechanism does not represent an exception to the weakly compressible hypothesis. © 2010 Cambridge University Press

    Pengaruh Metode Resitasi dalam Model Pembelajaran Kooperatif untuk Meningkatkan Hasil Belajar Materi Kalor dan Perpindahannya

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    The purpose of this study was to determine whether there is an effect of the recitation method in the cooperative learning model to improve the learning outcomes of heat and its transfer. This type of research was quasi-experimental. The sampling technique was purposive sampling. The samples of this research were students of class VII A and VII B of SMP Negeri 3 Bulagi. Class VII A is the experimental group and class VIIB is the control group. The learning outcome test instrument was a multiple-choice test. Based on the results of data processing, the N-gain value in the experimental group was obtained at 45.97%, which was in the medium category. Then for the control group, the N-gain value was obtained at 33.43%, which was also in the medium category. These results indicate that the learning outcomes of physics in the experimental group are higher than those in the control group. The results of statistical calculations from the average difference test using t-test (two-tailed) obtained tcount > ttable (tcount = 4.22 and ttable = 2.02) at a significance level of 5% and dk = 45, thus H0 is rejected and H1 is accepted. So, it can be concluded that there is an effect of the recitation method in the cooperative learning model to improve the learning outcomes of heat and its transfer

    Pyrolytic formation of polyaromatic hydrocarbons from steroid hormones

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    Four steroid hormones, namely androsterone, cholesterol, estrone and estradiol, have been pyrolysed at 300, 400 and 500 °C and the pyrolysates from these have been analysed by GC-MS. The results indicate that these formed different products under the pyrolysis and most of them evolved into polycyclic aromatic hydrocarbons during their residence in the pyrolysis chamber at high temperatures. The products from the pyrolysates, at all temperatures, were analysed for similarities and differences using multivariate data analysis. The products possessed some similarities on pyrolysis at 300 °C but were entirely different when pyrolysed at 500 °C. Androsterone and cholesterol formed a higher percentage of substituted PAH than did estrone and estradiol. These compounds included carcinogens, such as phenanthrene, methylphenanthrene, fluorene and its derivatives. The side chain of cholesterol had no effect on the products formed, while the presence of the aromatic ring in estrone and estradiol led to a higher percentage of phenol and its derivatives in the pyrolysates. Furthermore, estrone was subjected to flash pyrolysis and the products formed were compared with those which resulted from the long time pyrolysis: flash pyrolysis produced small amounts of PAH

    The Impact of Group Drumming on Social-Emotional Behavior in Low-Income Children

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    Low-income youth experience social-emotional problems linked to chronic stress that are exacerbated by lack of access to care. Drumming is a non-verbal, universal activity that builds upon a collectivistic aspect of diverse cultures and does not bear the stigma of therapy. A pretest-post-test non-equivalent control group design was used to assess the effects of 12 weeks of school counselor-led drumming on social-emotional behavior in two fifth-grade intervention classrooms versus two standard education control classrooms. The weekly intervention integrated rhythmic and group counseling activities to build skills, such as emotion management, focus and listening. The Teacher's Report Form was used to assess each of 101 participants (n = 54 experimental, n = 47 control, 90% Latino, 53.5% female, mean age 10.5 years, range 10–12 years). There was 100% retention. ANOVA testing showed that intervention classrooms improved significantly compared to the control group in broad-band scales (total problems (P < .01), internalizing problems (P < .02)), narrow-band syndrome scales (withdrawn/depression (P < .02), attention problems (P < .01), inattention subscale (P < .001)), Diagnostic and Statistical Manual of Mental Disorders-oriented scales (anxiety problems (P < .01), attention deficit/hyperactivity problems (P < .01), inattention subscale (P < .001), oppositional defiant problems (P < .03)), and other scales (post-traumatic stress problems (P < .01), sluggish cognitive tempo (P < .001)). Participation in group drumming led to significant improvements in multiple domains of social-emotional behavior. This sustainable intervention can foster positive youth development and increase student-counselor interaction. These findings underscore the potential value of the arts as a therapeutic tool

    Classical Scattering in 1+11+1 Dimensional String Theory

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    We find the general solution to Polchinski's classical scattering equations for 1+11+1 dimensional string theory. This allows efficient computation of scattering amplitudes in the standard Liouville ×\times c=1c=1 background. Moreover, the solution leads to a mapping from a large class of time-dependent collective field theory backgrounds to corresponding nonlinear sigma models. Finally, we derive recursion relations between tachyon amplitudes. These may be summarized by an infinite set of nonlinear PDE's for the partition function in an arbitrary time-dependent background.Comment: 15 p

    Quantum Group as Semi-infinite Cohomology

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    We obtain the quantum group SLq(2)SL_q(2) as semi-infinite cohomology of the Virasoro algebra with values in a tensor product of two braided vertex operator algebras with complementary central charges c+cˉ=26c+\bar{c}=26. Each braided VOA is constructed from the free Fock space realization of the Virasoro algebra with an additional q-deformed harmonic oscillator degree of freedom. The braided VOA structure arises from the theory of local systems over configuration spaces and it yields an associative algebra structure on the cohomology. We explicitly provide the four cohomology classes that serve as the generators of SLq(2)SL_q(2) and verify their relations. We also discuss the possible extensions of our construction and its connection to the Liouville model and minimal string theory.Comment: 50 pages, 7 figures, minor revisions, typos corrected, Communications in Mathematical Physics, in pres

    Emergence of film-thickness- and grain-size-dependent elastic properties in nanocrystalline thin films

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    Molecular dynamics simulations of nanocrystalline Ni revealed that the in-plane Young’s modulus of 2.2 nm grained Ni film with ∼10 grains across its thickness was only 0.64% smaller than that of bulk, while it dropped to 24.1% below bulk value for ∼1 grain across film. This size dependence arises from the increased number of more compliant grains adjacent to the free surface. Simulations of nanocrystalline diamond revealed that the anharmonicity of the potential curve determined the sensitivity of the Young’s modulus to variations in the sample size

    Recursion Relations in Liouville Gravity coupled to Ising Model satisfying Fusion Rules

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    The recursion relations of 2D quantum gravity coupled to the Ising model discussed by the author previously are reexamined. We study the case in which the matter sector satisfies the fusion rules and only the primary operators inside the Kac table contribute. The theory involves unregularized divergences in some of correlators. We obtain the recursion relations which form a closed set among well-defined correlators on sphere, but they do not have a beautiful structure that the bosonized theory has and also give an inconsistent result when they include an ill-defined correlator with the divergence. We solve them and compute the several normalization independent ratios of the well-defined correlators, which agree with the matrix model results.Comment: Latex, 22 page
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