28,065 research outputs found

    Evaporation of microdroplets of azeotropic liquids

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    This work reports data showing the evolution of contact angle with time for mixtures of water and 1-propanol at room temperature on poly(methyl methacrylate) (PMMA). The composition range investigated spans the azeotropic composition, thus encompassing systems containing excess water and excess 1-propanol. A discontinuity in the contact angle behavior is observed and it is suggested that this enables the identification of the azeotropic composition as 0.39 mole fraction of 1-propanol. This suggestion is supported by boiling point measurements made at around 20 mmHg. The discontinuity is associated with the presence of an instability, which causes a distortion around the droplet perimeter. It is suggested that the distortion is caused by competing effects of local surface tension maxima and minima

    Imaging African trypanosomes

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    Trypanosoma brucei are extracellular kinetoplastid parasites transmitted by the blood-sucking tsetse fly. They are responsible for the fatal disease human African trypanosomiasis (HAT), also known as sleeping sickness. In late-stage infection, trypanosomes cross the blood–brain barrier (BBB) and invade the central nervous system (CNS) invariably leading to coma and death if untreated. There is no available vaccine and current late-stage HAT chemotherapy consists of either melarsoprol, which is highly toxic causing up to 8% of deaths, or nifurtimox–eflornithine combination therapy (NECT), which is costly and difficult to administer. There is therefore an urgent need to identify new late-stage HAT drug candidates. Here, we review how current imaging tools, ranging from fluorescent confocal microscopy of live immobilized cells in culture to whole-animal imaging, are providing insight into T. brucei biology, parasite-host interplay, trypanosome CNS invasion and disease progression. We also consider how imaging tools can be used for candidate drug screening purposes that could lead to new chemotherapies

    Density Dependence of Transport Coefficients from Holographic Hydrodynamics

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    We study the transport coefficients of Quark-Gluon-Plasma in finite temperature and finite baryon density. We use AdS/QCD of charged AdS black hole background with bulk-filling branes identifying the U(1) charge as the baryon number. We calculate the diffusion constant, the shear viscosity and the thermal conductivity to plot their density and temperature dependences. Hydrodynamic relations between those are shown to hold exactly. The diffusion constant and the shear viscosity are decreasing as a function of density for fixed total energy. For fixed temperature, the fluid becomes less diffusible and more viscous for larger baryon density.Comment: LaTeX, 1+33 pages, 6 figures, references adde

    Agricultural use of Tasman Peninsula

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    The format of agriculture on Tasman Peninsula will be influenced in the future by thc same factors as in the past - the environment, enterprise viability and the desire and capacity of landowners to obtain expertise and raise capital. The high levels of investment required to establish viable farming enterprises and the doubt about obtaining a good return restricts present landowners from changing the existing type and scale of primary production

    Nutrition problems in Tasmania

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    A Biometric study of the conidia of Macrosporium and Alternaria

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    Alternaria and Macrosporium are closely allied genera of the Hyphomyctaceae, both being included in the section Dictyosporae of the Dematicae. They are differentiated by their methods of conidia-formation. In Macrosporium a conidiophore bears at its apex a single conidium, which attains its full size, matures, and finally becomes detached. In the case of Alternaria, the conidiophore produces at its apex a chain of conidia, each of which is morphologically identical with the single conidium of Macrosporiurn. This chain of conidia produced by Alternaria eventually becomes broken up into individuals which cannot be distinguished from a detached conidium of Macrosporimn. It is, therefore, only possible to refer a particular species to one or other of these two genera when the manner in which the conidia are produced has been determined. Consequently, many species have been incorrectly placed, owing to inaccurate observations on the conidia and method of conidia-formation. The abundance of species apparently placed indiscriminately in either genus and having synonyms in the complementary genus is evidence of the fact that these two genera are much confused. Thus Alternaria solani, Sorauer= Macrosporium solani, E. & M

    Red cell antibody problems in 1000 liver transplants

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    Liver transplant patients frequently require large amounts of blood. The frequency and nature of their red cell (RBC) antibody problems were examined. Records were reviewed in 496 adults and 286 children undergoing 1000 consecutive transplants. Twenty‐two percent of adults and 14 percent of children had RBC alloantibodies. Antibodies of potential clinical significance were found before transplant in 6.3 percent of adults and 1.0 percent of children; despite immunosuppression, they appeared 1 to 5 weeks after transplant in an additional 7.5 and 5.2 percent respectively. These antibodies probably represented secondary immune responses. Of 58 transplant patients with prior potentially significant antibodies, 8 required 7 to 110 units of antigen‐untyped blood after 8 to 28 units of antigen‐negative blood; of these patients, one had subsequent hemolysis. Positive direct antiglobulin tests in 24 percent of adults and 10 percent of children were most often thought to be due to nonspecific adsorption of IgG. Anti‐recipient ABO antibodies developed in 22 of 60 (37%) evaluable ABO‐unmatched grafts; 13 cases had associated hemolysis. In all, 36 percent of adults and 20 percent of children had diverse RBC antibody problems. Resolution of these problems is an important part of the laboratory support necessary for a liver transplantation program. 1989 AAB

    The Cosmological Constant From The Viewpoint Of String Theory

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    The mystery of the cosmological constant is probably the most pressing obstacle to significantly improving the models of elementary particle physics derived from string theory. The problem arises because in the standard framework of low energy physics, there appears to be no natural explanation for vanishing or extreme smallness of the vacuum energy, while on the other hand it is very difficult to modify this framework in a sensible way. In seeking to resolve this problem, one naturally wonders if the real world can somehow be interpreted in terms of a vacuum state with unbroken supersymmetry.Comment: 12 pp., Lecture at DM2000, new reference and more conservative scenario adde
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