12,325 research outputs found

    Antiferromagnetic order in CeCoIn5 oriented by spin-orbital coupling

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    An incommensurate spin density wave (QQ phase) confined inside the superconducting state at high basal plane magnetic field is an unique property of the heavy fermion metal CeCoIn5_5. The neutron scattering experiments and the theoretical studies point out that this state come out from the soft mode condensation of magnetic resonance excitations. We show that the fixation of direction of antiferromagnetic modulations by a magnetic field reported by Gerber et al., Nat. Phys. {\bf 10}, 126 (2014) is explained by spin-orbit coupling. This result, obtained on the basis of quite general phenomenological arguments, is supported by the microscopic derivation of the χzz\chi_{zz} susceptibility dependence on the mutual orientation of the basal plane magnetic field and the direction of modulation of spin polarization in a multi-band metal.Comment: 7 pages plus 2 pages with 2 figure

    The MUCHFUSS photometric campaign

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    Hot subdwarfs (sdO/Bs) are the helium-burning cores of red giants, which lost almost all of their hydrogen envelopes. This mass loss is often triggered by common envelope interactions with close stellar or even substellar companions. Cool companions like late-type stars or brown dwarfs are detectable via characteristic light curve variations like reflection effects and often also eclipses. To search for such objects we obtained multi-band light curves of 26 close sdO/B binary candidates from the MUCHFUSS project with the BUSCA instrument. We discovered a new eclipsing reflection effect system (P=0.168938P=0.168938~d) with a low-mass M dwarf companion (0.116M0.116 M_{\rm \odot}). Three more reflection effect binaries found in the course of the campaign were already published, two of them are eclipsing systems, in one system only showing the reflection effect but no eclipses the sdB primary is found to be pulsating. Amongst the targets without reflection effect a new long-period sdB pulsator was discovered and irregular light variations were found in two sdO stars. The found light variations allowed us to constrain the fraction of reflection effect binaries and the substellar companion fraction around sdB stars. The minimum fraction of reflection effect systems amongst the close sdB binaries might be greater than 15\% and the fraction of close substellar companions in sdB binaries might be as high as 8.0%8.0\%. This would result in a close substellar companion fraction to sdB stars of about 3\%. This fraction is much higher than the fraction of brown dwarfs around possible progenitor systems, which are solar-type stars with substellar companions around 1 AU, as well as close binary white dwarfs with brown dwarf companions. This might be a hint that common envelope interactions with substellar objects are preferentially followed by a hot subdwarf phase.Comment: accepted for A&

    Transverse "resistance overshoot" in a Si/SiGe two-dimensional electron gas in the quantum Hall effect regime

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    We investigate the peculiarities of the "overshoot" phenomena in the transverse Hall resistance R_{xy} in Si/SiGe. Near the low magnetic field end of the quantum Hall effect plateaus, when the filling factor \nu approaches an integer i, R_{xy} overshoots the normal plateau value h/ie^2. However, if magnetic field B increases further, R_{xy} decreases to its normal value. It is shown that in the investigated sample n-Si/Si_{0.7}Ge_{0.3}, overshoots exist for almost all \nu. Existence of overshoot in R_{xy} observed in different materials and for different \nu, where splitting of the adjacent Landau bands has different character, hints at the common origin of this effect. Comparison of the experimental curves R_{xy}(\nu) for \nu = 3 and \nu = 5 with and without overshoot showed that this effect exist in the whole interval between plateaus, not only in the region where R_{xy} exceeds the normal plateau value.Comment: 3 pages, 5 EPS figure

    Inflammatory Airway Disease of Horses - Revised Consensus Statement

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    The purpose of this manuscript is to revise and update the previous consensus statement on inflammatory airway disease (IAD) in horses. Since 2007, a large number of scientific articles have been published on the topic and these new findings have led to a significant evolution of our understanding of IAD

    Gravitational potential of a homogeneous circular torus: new approach

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    The integral expression for gravitational potential of a homogeneous circular torus composed of infinitely thin rings is obtained. Approximate expressions for torus potential in the outer and inner regions are found. In the outer region a torus potential is shown to be approximately equal to that of an infinitely thin ring of the same mass; it is valid up to the surface of the torus. It is shown in a first approximation, that the inner potential of the torus (inside a torus body) is a quadratic function of coordinates. The method of sewing together the inner and outer potentials is proposed. This method provided a continuous approximate solution for the potential and its derivatives, working throughout the region.Comment: 10 pages, 9 figures, 1 table; some misprints in formulae were correcte

    Variable range cotunneling and conductivity of a granular metal

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    The Efros-Shklovskii law for the conductivity of granular metals is interpreted as a result of a variable range cotunneling process. The cotunneling between distant resonant grains is predominantly elastic at low T << T_c, while it is inelastic (i.e., accompanied by creation of electron-hole pairs on a string of intermediate non-resonant grains) at T > T_c. The corresponding E-S temperature T_ES in the latter case is slightly (logarithmically) T-dependent. The magnetoresistance in the two cases is different: it may be relatively strong and negative at T much below T_c, while at T>T_c it is suppressed due to inelastic processes which destroy the interference.Comment: Submitted to JETP Letter

    Universal temperature dependence of the conductivity of a strongly disordered granular metal

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    A disordered array of metal grains with large and random intergrain conductances is studied within the one-loop accuracy renormalization group approach. While at low level of disorder the dependence of conductivity on log T is nonuniversal (it depends on details of the array's geometry), for strong disorder this dependence is described by a universal nonlinear function, which depends only on the array's dimensionality. In two dimensions this function is found numerically. The dimensional crossover in granular films is discussed.Comment: 6 pages, 6 figures, submitted to JETP Letter

    Diagnostic utility and validity of 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6'-methylresorufin) ester (DGGR) lipase activity in horses with colic.

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    Little is known about the clinical usefulness in horses of the 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6'-methylresorufin) ester (DGGR) lipase assay, a biomarker used in other species for the detection of pancreatitis. The main objectives of this study were to evaluate the prevalence of increased DGGR-lipase activity in horses with signs of colic and investigate its association with, and validity to diagnose, underlying gastrointestinal diseases, treatment method (medical or surgical), and outcome (survival or non-survival). Clinical data from 192 horses presented for colic to a teaching hospital were analysed retrospectively. DGGR-lipase activity was measured in frozen plasma collected within 24h of presentation. Non-parametric tests and Chi-squared or Fisher's exact tests were used to evaluate differences and associations between DGGR-lipase activity and continuous and categorical variables or outcomes, respectively. Measures of the validity of DGGR-lipase as a diagnostic test were also calculated. Increased DGGR-lipase activity above published reference limits was demonstrated in 30.2% of horses with signs of colic, and was above 2x the upper reference limit (URL) in 15.6%. The median DGGR-lipase activity in horses with large bowel displacement or torsion was significantly higher than the median activity for large bowel impaction and for gastric impaction, dilation, or ulceration. DGGR-lipase activity >2x URL was significantly associated with surgical treatment, strangulating disease, and non-survival. However, as a diagnostic or screening test for these target outcomes, DGGR-lipase activity was poor to fair consequent to poor sensitivity, poor negative likelihood ratio, and an area under the receiver operating characteristic curve, with optimal cut-offs based on the Youden Index, within reference limits

    Owner reported clinical signs and -treatment decisions in equine pastern dermatitis.

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    INTRODUCTION Equine pastern dermatitis has a high prevalence in the equine population, especially in draft breeds. This skin condition is difficult to treat, and it is suspected that owners often decide on a treatment without consulting a veterinarian. The objectives of this study were to describe owner-reported clinical signs, severity, and reasons to consult a veterinarian. Moreover, we inquired about preventive measures and treatments, both instituted by owners without previous consultation or prescribed by their veterinarians. A total of 123 horses (owners recruited over social media) were included in the study. All horses suffered from equine pastern dermatitis at least once in the two years preceding the study. Standardized questionnaires collecting information on management, housing conditions, clinical signs as well as preventive measures and treatments were filled out by participants. The data was recorded, and descriptive statistics were performed. Most horses (71 out of 115 available answers, 62 %) had shown clinical signs of equine pastern dermatitis at least four times in their lives. A total of 113 horses (92 % of all included horses) were affected by equine pastern dermatitis at the time of the interview. For 37 horses (32 %) out of 114 available answers the owners consulted their veterinarian only after the horse showed signs of pain or lameness. Usually, treatments that did not require a medical prescription were applied without consulting their veterinarian (e. g. only 9 % (14 out of 150 prescriptions) of topical creams promoting wound healing were prescribed by a veterinarian). A total of 31 treatment decisions (55 %) with creams containing anti-bacterial, anti-mycotic and/or anti-inflammatory agents and 100 % of systemic medications containing anti-bacterial, anti-parasitic or anti-inflammatory agents were prescribed by veterinarians. Overall, 69 % of treatment decisions were made without consulting a veterinarian, making it then more difficult to determine underlying causes for the pastern dermatitis and rendering the treatment often longer and more onerous. To raise owner awareness of possible consequences if a veterinarian is consulted too late in the disease process, specific information campaigns to improve animal welfare should be considered
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