26,503 research outputs found

    Effect of Particle Shape and Charge on Bulk Rheology of Nanoparticle Suspensions

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    The rheology of nanoparticle suspensions for nanoparticles of various shapes with equal mass is studied using molecular dynamics simulations. The equilibrium structure and the response to imposed shear are analyzed for suspensions of spheres, rods, plates, and jacks in an explicit solvent for both charged and uncharged nanoparticles. For the volume fraction studied, ?ϕvf=0.075\phi_{vf}=0.075, the uncharged systems are all in their isotropic phase and the viscosity is only weakly dependent on shape for spheres, rods, and plate whereas for the jacks the viscosity is an order of magnitude larger than for the other three shapes. The introduction of charge increases the viscosity for all four nanoparticle shapes with the increase being the largest for rods and plates. The presence of a repulsive charge between the particles decreases the amount of stress reduction that can be achieved by particle reorientation.Comment: 15 pages, 9 figures, in pres

    Self-degradation of heat shock proteins

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    The 70-kDa heat shock protein of Drosophila decays in vivo at a much faster rate than other abundantly labeled proteins. Degradation also occurs in vitro, even during electrophoresis. It appears that this degradation is not mediated by a general protease and that the 70-kDa heat shock protein has a slow proteolytic action upon itself. Heat-induced proteins in CHO cells and a mouse cell line also degrade spontaneously in vitro, as do certain non-heat shock proteins from Drosophila tissues as well as the cell lines

    Anomalous Chiral Action from the Path-Integral

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    By generalizing the Fujikawa approach, we show in the path-integral formalism: (1) how the infinitesimal variation of the fermion measure can be integrated to obtain the full anomalous chiral action; (2) how the action derived in this way can be identified as the Chern-Simons term in five dimensions, if the anomaly is consistent; (3) how the regularization can be carried out, so as to lead to the consistent anomaly and not to the covariant anomaly. Our method uses Schwinger's ``proper-time'' representation of the Green's function and the gauge invariant point-splitting technique. We find that the consistency requirement and the point-splitting technique allow both an anomalous and a non-anomalous action. In the end, the nature of the vacuum determines whether we have an anomalous theory, or, a non-anomalous theoryComment: 28 page

    How Sensitive are Di-Leptons from Rho Mesons to the High Baryon Density Region?

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    We show that the measurement of di-leptons might provide only a restricted view into the most dense stages of heavy ion reactions. Thus, possible studies of meson and baryon properties at high baryon densities, as e.g. done at GSI-HADES and envisioned for FAIR-CBM, might observe weaker effects than currently expected in certain approaches. We argue that the strong absorption of resonances in the high baryon density region of the heavy ion collision masks information from the early hot and dense phase due to a strong increase of the total decay width because of collisional broadening. To obtain additional information, we also compare the currently used approaches to extract di-leptons from transport simulations - i.e. shining, only vector mesons from final baryon resonance decays and instant emission of di-leptons and find a strong sensitivity on the method employed in particular at FAIR and SPS energies. It is shown explicitly that a restriction to rho meson (and therefore di-lepton) production only in final state baryon resonance decays provide a strong bias towards rather low baryon densities. The results presented are obtained from UrQMD v2.3 calculations using the standard set-up.Comment: 8 pages, 6 figures, expanded versio

    Differential patterns of PMN-elastase and type III procollagen peptide in knee joint effusions due to acute and chronic sports injuries

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    In 38 traumatic knee joint effusions the proteolytic enzyme PMN-elastase (PMN-E) and the repair marker procollagen III aminoterminal peptide (PIIINP) were determined. According to the period between trauma and first aspiration of the effusion, the patients were divided into 3 groups. Group I (17 patients; period between trauma and first aspiration not longer than 72 hours) showed high concentrations of PMN-E (up to 5400 ng/ml) and low concentrations of PIIINP (<13 U/ml). Group II (11 patients; aspiration within 4 to 14 days) had mean PMN-E and PIIINP concentrations of 125.6 ng/ml and 52.1 U/ ml, respectively. In group III (10 patients, aspiration after 14 days) mean PMN-E concentration was 123.8 ng/ml and mean PIIINP concentration was 63.4 U/ml. Graphic depiction of PMN-E and PIIINP levels in each individual sample as a function of time between trauma and fluid collection revealed highly increasing PMN-E levels during the first 24 posttraumatic hours, followed by rapidly decreasing levels within 72 hours post trauma, and no change after the 4th posttraumatic day. In contrast, PIIINP increased continuously up to the first posttraumatic week and stayed at high levels up to 90 days (end of the observation period). The differential patterns of PMN-E and PIIINP concentration in knee joint effusions may be useful in estimating the period between trauma and first treatment (aspiration of effusion) and should, therefore, be helpful in detecting degenerative lesions, which seem to be characterized by low PMN-E concomitantly with high PIIINP levels

    Naturen er bedre i økologiske hegn og skel

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    Det glædelige er at selv ret unge økologiske hegn og relativt nyomlagte bedrifter tilsyneladende også har stor betydning for agerlandets natur. En mere varieret hegnsvegetation giver flere levemuligheder også for andre arter, både insekter og højere dyr. Med omtanke kan landmanden altså påvirke og beskytte naturen i skel og hegn via sin daglige drift og dermed bidrage til at forbedre naturen i agerlandskabet

    Multiple stressors in a top predator seabird: potential ecological consequences of environmental contaminants, population health and breeding conditions

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    Environmental contaminants may have impacts on reproduction and survival in wildlife populations suffering from multiple stressors. This study examined whether adverse effects of persistent organic pollutants (POPs) increased with poor population health and breeding conditions in three colonies (60–74°N) of great skua (Stercorarius skua) in the north-eastern Atlantic (Shetland, Iceland and Bjørnøya [Bear Island]). POPs (organochlorines [OCs] and polybrominated diphenyl ethers [BDEs]) were measured in plasma of incubating birds (n = 222), concentrations differing nearly tenfold among colonies: Bjørnøya (2009) &gt; Bjørnøya (2010) &gt; Iceland (2009) &gt; Shetland (2009). Reproductive success (hatching success and chick survival) showed that breeding conditions were favourable in Shetland and at Bjørnøya (2010), but were very poor in Iceland and at Bjørnøya (2009). Biomarkers indicated that health was poor in the Shetland population compared to the other populations. Females whose chicks hatched late had high POP concentrations in all colonies except at Bjørnøya (2010), and females losing their eggs at Bjørnøya (2009) tended to have higher concentrations than those hatching. Moreover, there was a negative relationship between female POP concentrations and chick body condition at hatching in Iceland and at Bjørnøya (2010). Supplementary feeding experiments were conducted, and in Iceland where feeding conditions were poor, significant negative relationships were found between female POP concentrations and daily growth-rate in first-hatched chicks of control nests, but not in food supplemented nests. This suggests that negative impacts of POPs were mitigated by improved feeding conditions. For second-chicks, there was a strong negative relationship between the female POP concentrations and growth-rate, but no effects of supplementary feeding. Lowered adult return-rate between breeding seasons with increasing POP loads were found both at Bjørnøya (2009) and in Shetland, especially related to BDEs. This indicates stronger fitness consequences of POPs following seasons with very poor breeding conditions and/or high reproductive effort. This study suggests that the impacts of POPs may differ depending on population health and breeding conditions, and that even low concentrations of POPs could have ecological consequences during adverse circumstances. This is important with regard to risk assessment of biomagnifying contaminants in marine ecosystems

    Lower bounds for heights in relative Galois extensions

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    The goal of this paper is to obtain lower bounds on the height of an algebraic number in a relative setting, extending previous work of Amoroso and Masser. Specifically, in our first theorem, we obtain an effective bound for the height of an algebraic number α\alpha when the base field K\mathbb{K} is a number field and K(α)/K\mathbb{K}(\alpha)/\mathbb{K} is Galois. Our second result establishes an explicit height bound for any nonzero element α\alpha which is not a root of unity in a Galois extension F/K\mathbb{F}/\mathbb{K}, depending on the degree of K/Q\mathbb{K}/\mathbb{Q} and the number of conjugates of α\alpha which are multiplicatively independent over K\mathbb{K}. As a consequence, we obtain a height bound for such α\alpha that is independent of the multiplicative independence condition
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