792 research outputs found

    Vortex Fluctuations in High-Tc Films: Flux Noise Spectrum and Complex Impedance

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    The flux noise spectrum and complex impedance for a 500 {\AA} thick YBCO film are measured and compared with predictions for two dimensional vortex fluctuations. It is verified that the complex impedance and the flux noise spectra are proportional to each other, that the logarithm of the flux noise spectra for different temperatures has a common tangent with slope ≈−1\approx -1, and that the amplitude of the noise decreases as d−3d^{-3}, where dd is the height above the film at which the magnetic flux is measured. A crossover from normal to anomalous vortex diffusion is indicated by the measurements and is discussed in terms of a two-dimensional decoupling.Comment: 5 pages including 4 figures in two columns, to appear in Phys. Rev. Let

    Vortex dynamics for two-dimensional XY models

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    Two-dimensional XY models with resistively shunted junction (RSJ) dynamics and time dependent Ginzburg-Landau (TDGL) dynamics are simulated and it is verified that the vortex response is well described by the Minnhagen phenomenology for both types of dynamics. Evidence is presented supporting that the dynamical critical exponent zz in the low-temperature phase is given by the scaling prediction (expressed in terms of the Coulomb gas temperature TCGT^{CG} and the vortex renormalization given by the dielectric constant ϵ~\tilde\epsilon) z=1/ϵ~TCG−2≥2z=1/\tilde{\epsilon}T^{CG}-2\geq 2 both for RSJ and TDGL and that the nonlinear IV exponent a is given by a=z+1 in the low-temperature phase. The results are discussed and compared with the results of other recent papers and the importance of the boundary conditions is emphasized.Comment: 21 pages including 15 figures, final versio

    Molecular astronomy of cool stars and sub-stellar objects

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    The optical and infrared spectra of a wide variety of `cool' astronomical objects including the Sun, sunspots, K-, M- and S-type stars, carbon stars, brown dwarfs and extrasolar planets are reviewed. The review provides the necessary astronomical background for chemical physicists to understand and appreciate the unique molecular environments found in astronomy. The calculation of molecular opacities needed to simulate the observed spectral energy distributions is discussed

    Contrasting effects of high-starch and high-sugar diets on ruminal function in cattle

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    The experiment reported in this research paper aimed to determine whether clinical and subclinical effects on cattle were similar if provided with isoenergetic and isonitrogenous challenge diets in which carbohydrate sources were predominantly starch or sugar. The study was a 3 × 3 Latin square using six adult Jersey cows with rumen cannulae, over 9 weeks. In the first 2 weeks of each 3 week experimental period cows were fed with a maintenance diet and, in the last week, each animal was assigned to one of three diets: a control diet (CON), being a continuation of the maintenance diet; a high starch (HSt) or a high sugar (HSu) diet. Reticuloruminal pH and motility were recorded throughout the study period. Blood and ruminal samples were taken on day-1 (TP-1), day-2 (TP-2) and day-7 (TP-7) of each challenge week. Four clinical variables were recorded daily: diarrhoea, inappetence, depression and ruminal tympany. The effects of treatment, hour of day and day after treatment on clinical parameters were analysed using linear mixed effects (LME) models. Although both challenge diets resulted in a decline in pH, an increase in the absolute pH residuals and an increase in the number of minutes per day under pH 5.8, systemic inflammation was only detected with the HSt diet. The challenge diets differentially modified amplitude and period of reticuloruminal contractions compared with CON diet and both were associated with an increased probability of diarrhoea. The HSu diet reduced the probability of an animal consuming its complete allocation. Because the challenge diets were derived from complex natural materials (barley and molasses respectively), it is not possible to assign all the differential effects to the difference in starch and sugar concentration: non-starch components of barley or non-sugar components of molasses might have contributed to some of the observations. In conclusion, substituting much of the starch with sugar caused no substantial reduction in the acidosis load, but inflammatory response was reduced while feed rejection was increased

    Refining complexity analyses in planning by exploiting the exponential time hypothesis

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    The use of computational complexity in planning, and in AI in general, has always been a disputed topic. A major problem with ordinary worst-case analyses is that they do not provide any quantitative information: they do not tell us much about the running time of concrete algorithms, nor do they tell us much about the running time of optimal algorithms. We address problems like this by presenting results based on the exponential time hypothesis (ETH), which is a widely accepted hypothesis concerning the time complexity of 3-SAT. By using this approach, we provide, for instance, almost matching upper and lower bounds onthe time complexity of propositional planning.Funding Agencies|National Graduate School in Computer Science (CUGS), Sweden; Swedish Research Council (VR) [621-2014-4086]</p

    Scalar Solitons on the Fuzzy Sphere

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    We study scalar solitons on the fuzzy sphere at arbitrary radius and noncommutativity. We prove that no solitons exist if the radius is below a certain value. Solitons do exist for radii above a critical value which depends on the noncommutativity parameter. We construct a family of soliton solutions which are stable and which converge to solitons on the Moyal plane in an appropriate limit. These solutions are rotationally symmetric about an axis and have no allowed deformations. Solitons that describe multiple lumps on the fuzzy sphere can also be constructed but they are not stable.Comment: 24 pages, 2 figures, typo corrected and stylistic changes. v3: reference adde

    Use of granulocyte colony-stimulating factor and risk of relapse in pediatric patients treated for acute myeloid leukemia according to NOPHO-AML 2004 and DB AML-01

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    Background Supportive-care use of granulocyte colony-stimulating factor (G-CSF) in pediatric acute myeloid leukemia (AML) remains controversial due to a theoretical increased risk of relapse and limited impact on neutropenic complications. We describe the use of G-CSF in patients treated according to NOPHO-AML 2004 and DB AML-01 and investigated associations with relapse. Procedure Patients diagnosed with de novo AML completing the first week of therapy and not treated with hematopoietic stem cell transplantation in the first complete remission were included (n = 367). Information on G-CSF treatment after each course (yes/no) was registered prospectively in the study database and detailed information was gathered retrospectively from each center. Descriptive statistics were used to describe G-CSF use and Cox regression to assess the association between G-CSF and risk of relapse. Results G-CSF as supportive care was given to 128 (35%) patients after 268 (39%) courses, with a large variation between centers (0-93%). The use decreased with time-the country-adjusted odds ratio was 0.8/diagnostic year (95% confidence interval [CI] 0.7-0.9). The median daily dose was 5 mu g/kg (range 3-12 mu g/kg) and the median cumulative dose was 75 mu g/kg (range 7-1460 mu g/kg). Filgrastim was used in 82% of G-CSF administrations and infection was the indication in 44% of G-CSF administrations. G-CSF was associated with increased risk of relapse-the adjusted hazard ratio was 1.5 (95% CI 1.1-2.2). Conclusions G-CSF as supportive care was used in a third of patients, and use decreased with time. Our results indicate that the use of G-CSF may be associated with an increased risk of relapse.Peer reviewe

    Microgels and apparatus for PAGE of nucleic acids in one or two dimensions

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    To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesWe describe a system for horizontal 1D or 2D PAGE comprising an apparatus and microgels. There is no buffer outside the gel, making handling and sample loading easy. Specially designed electrodes on all four sides allow 2D electrophoresis without gel rotation. Electrophoresis is completed within 20 min and sensitivity is in the subnanogram range. The system is temperature controlled for speed, denaturation of nucleic acid molecules and maintaining molecules single-stranded. The system allows characterization of structure, conformation and damage in complex nucleic acid preparations. Besides quick 1D PAGE, 2D applications include characterization of efficiency of complex molecular procedures, checking quality of biosamples and detecting DNA damage in cells and body fluids. The system should also run protein gels.Scottish Government Icelandic Technology Development Fund grant
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