2,146 research outputs found

    The flux pinning force and vortex phase diagram of single crystal FeTe0.60Se0.40

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    The flux pinning force density (Fp) of the single crystalline FeTe0.60Se0.40 superconductor has been calculated from the magnetization measurements. The normalized Fp versus h (=H/Hirr) curves are scaled using the Dew-Hughes formula to underline the pinning mechanism in the compound. The obtained values of pinning parameters p and q indicate the vortex pinning by the mixing of the surface and the point core pinning of the normal centers. The vortex phase diagram has also been drawn for the first time for the FeTe0.60Se0.40, which has very high values of critical current density Jc ~ 1.10(5) Amp/cm2 and the upper critical field Hc2(0) = 65T, with a reasonably high transition temperature Tc =14.5K.Comment: 12 pages, 4 figure

    Blow up criterion for compressible nematic liquid crystal flows in dimension three

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    In this paper, we consider the short time strong solution to a simplified hydrodynamic flow modeling the compressible, nematic liquid crystal materials in dimension three. We establish a criterion for possible breakdown of such solutions at finite time in terms of the temporal integral of both the maximum norm of the deformation tensor of velocity gradient and the square of maximum norm of gradient of liquid crystal director field.Comment: 22 page

    Chinese adzuki bean germplasm: 1. Evaluation of agronomic traits

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    A core collection of adzuki beans, representing the germplasm of Chinese land races, was screened at Warwick Australia in a replicated yield trial sown mid-summer. Grain yield, yield components, phenologic traits, vegetative characteristics, and morphologic descriptors were recorded for all accessions plus Japanese-derived check varieties. Accessions from southern China were later flowering, had smaller seed, and grew taller than those from central China. Grain yield was greatest for accessions from central China, whereas both north Chinese and Japanese check accessions were generally low yielding. The evaluation of diversity displayed trends associated with latitude of germplasm origin, which were positive or negative according to the trait. Similarly, the germplasm diversity in duration of crop growth phases and in rate of yield expression was also associated with latitude of landrace origin. Localised variations from these trends were found for seed size and for number of pods per plant. Various trends with latitude of origin were found for natural incidence of powdery mildew, for growth habit, plant height, vining and leaf colour. However, traits not associated with latitude of germplasm origin included primary and secondary seed colour, mature pod colour, and degree of branching. The evaluation suggests that selections from this greater range of genetic diversity may allow higher yielding varieties than the current Japanese-derived standards to be developed for Australia

    Generalized Buneman pruning for inferring the most parsimonious multi-state phylogeny

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    Accurate reconstruction of phylogenies remains a key challenge in evolutionary biology. Most biologically plausible formulations of the problem are formally NP-hard, with no known efficient solution. The standard in practice are fast heuristic methods that are empirically known to work very well in general, but can yield results arbitrarily far from optimal. Practical exact methods, which yield exponential worst-case running times but generally much better times in practice, provide an important alternative. We report progress in this direction by introducing a provably optimal method for the weighted multi-state maximum parsimony phylogeny problem. The method is based on generalizing the notion of the Buneman graph, a construction key to efficient exact methods for binary sequences, so as to apply to sequences with arbitrary finite numbers of states with arbitrary state transition weights. We implement an integer linear programming (ILP) method for the multi-state problem using this generalized Buneman graph and demonstrate that the resulting method is able to solve data sets that are intractable by prior exact methods in run times comparable with popular heuristics. Our work provides the first method for provably optimal maximum parsimony phylogeny inference that is practical for multi-state data sets of more than a few characters.Comment: 15 page

    Supercritical biharmonic equations with power-type nonlinearity

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    The biharmonic supercritical equation Δ2u=∣u∣p−1u\Delta^2u=|u|^{p-1}u, where n>4n>4 and p>(n+4)/(n−4)p>(n+4)/(n-4), is studied in the whole space Rn\mathbb{R}^n as well as in a modified form with λ(1+u)p\lambda(1+u)^p as right-hand-side with an additional eigenvalue parameter λ>0\lambda>0 in the unit ball, in the latter case together with Dirichlet boundary conditions. As for entire regular radial solutions we prove oscillatory behaviour around the explicitly known radial {\it singular} solution, provided p∈((n+4)/(n−4),pc)p\in((n+4)/(n-4),p_c), where pc∈((n+4)/(n−4),∞]p_c\in ((n+4)/(n-4),\infty] is a further critical exponent, which was introduced in a recent work by Gazzola and the second author. The third author proved already that these oscillations do not occur in the complementing case, where p≥pcp\ge p_c. Concerning the Dirichlet problem we prove existence of at least one singular solution with corresponding eigenvalue parameter. Moreover, for the extremal solution in the bifurcation diagram for this nonlinear biharmonic eigenvalue problem, we prove smoothness as long as p∈((n+4)/(n−4),pc)p\in((n+4)/(n-4),p_c)

    Viability of competing field theories for the driven lattice gas

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    It has recently been suggested that the driven lattice gas should be described by a novel field theory in the limit of infinite drive. We review the original and the new field theory, invoking several well-documented key features of the microscopics. Since the new field theory fails to reproduce these characteristics, we argue that it cannot serve as a viable description of the driven lattice gas. Recent results, for the critical exponents associated with this theory, are re-analyzed and shown to be incorrect.Comment: 4 pages, revtex, no figure

    Experimental studies, molecular simulation and process modelling\simulation of adsorption-based post-combustion carbon capture for power plants: a state-of-the-art review

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    Adsorption-based post-combustion carbon capture is a promising emerging technology for capturing CO2 emissions from fossil-fueled power plants due to the ease of adsorbent regeneration in comparison with solvent-based technologies. To increase its competitiveness, research efforts have focused on the development of new adsorbent materials and processes. This paper presents a state-of-the-art review of such efforts, focusing on lab synthesis and characterization of adsorbent materials, (carbon capture) experimental studies, molecular simulation, process modelling\simulation and techno-economic analysis. Most experimental studies on adsorption-based post-combustion capture are at bench scale. Just a few experimental studies are at pilot scale. There are currently no commercial deployment of adsorption-based post-combustion capture technology. This review paper points out challenges encountered in these experimental investigations utilizing different adsorbent materials, limiting its commercial deployment. These gaps in experimental investigations need further research especially in the chemical modification of the adsorbent materials to increase the adsorption capacity. Molecular simulation of adsorbents and process modelling\simulation of carbon capture processes are cost-effective and time efficient approaches for the assessment of adsorbents’ CO2 capture performance. The review also highlighted the need for more research in the model development of adsorbent materials at molecular scale and the model development of adsorption-based post-combustion process adopting new reactor configurations to further reduce the cost of CO2 capture

    Structural and dielectric properties of Sr2_{2}TiO4_{4} from first principles

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    We have investigated the structural and dielectric properties of Sr2_{2}TiO4_{4},the first member of the Srn+1_{n+1}Tin_{n}O3n+1_{3n+1} Ruddlesden-Popper series, within density functional theory. Motivated by recent work in which thin films of Sr2_{2}TiO4_{4} were grown by molecular beam epitaxy (MBE) on SrTiO3_{3} substrates, the in-plane lattice parameter was fixed to the theoretically optimized lattice constant of cubic SrTiO3_{3} (n=∞\infty), while the out-of-plane lattice parameter and the internal structural parameters were relaxed. The fully relaxed structure was also investigated. Density functional perturbation theory was used to calculate the zone-center phonon frequencies, Born effective charges, and the electronic dielectric permittivity tensor. A detailed study of the contribution of individual infrared-active modes to the static dielectric permittivity tensor was performed. The calculated Raman and infrared phonon frequencies were found to be in agreement with experiment where available. Comparisons of the calculated static dielectric permittivity with experiments on both ceramic powders and epitaxial thin films are discussed.Comment: 11 pages, 1 figure, 8 tables, submitted to Phys. Rev.

    Gene expression identifies metabolic and functional differences between intramuscular and subcutaneous adipocytes in cattle

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    Background This study used a genome-wide screen of gene expression to better understand the metabolic and functional differences between commercially valuable intramuscular fat (IMF) and commercially wasteful subcutaneous (SC) fat depots in Bos taurus beef cattle. Results We confirmed many findings previously made at the biochemical level and made new discoveries. The fundamental lipogenic machinery, such as ACACA and FASN encoding the rate limiting Acetyl CoA carboxylase and Fatty Acid synthase were expressed at 1.6–1.8 fold lower levels in IMF, consistent with previous findings. The FA elongation pathway including the rate limiting ELOVL6 was also coordinately downregulated in IMF compared to SC as expected. A 2-fold lower expression in IMF of ACSS2 encoding Acetyl Coenzyme A synthetase is consistent with utilisation of less acetate for lipogenesis in IMF compared to SC as previously determined using radioisotope incorporation. Reduced saturation of fat in the SC depot is reflected by 2.4 fold higher expression of the SCD gene encoding the Δ9 desaturase enzyme. Surprisingly, CH25H encoding the cholesterol 25 hydroxylase enzyme was ~ 36 fold upregulated in IMF compared to SC. Moreover, its expression in whole muscle tissue appears representative of the proportional representation of bovine marbling adipocytes. This suite of observations prompted quantification of a set of oxysterols (oxidised forms of cholesterol) in the plasma of 8 cattle exhibiting varying IMF. Using Liquid Chromatography-Mass Spectrometry (LC-MS) we found the levels of several oxysterols were significantly associated with multiple marbling measurements across the musculature, but (with just one exception) no other carcass phenotypes. Conclusions These data build on our molecular understanding of ruminant fat depot biology and suggest oxysterols represent a promising circulating biomarker for cattle marbling
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