6,734 research outputs found

    Multi-vortex dynamics in junctions of charge density waves

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    Ground state reconstruction by creation of topological defects in junctions of CDWs is a convenient playground for modern efforts of field-effect transformations in strongly correlated materials with spontaneous symmetry breakings. Being transient, this effect contributes also to another new science of pump-induced phase transitions. We present a dynamical model for behavior of the CDW in restricted geometries of junctions under an applied voltage or a passing current. The model takes into account multiple interacting fields: the amplitude and the phase of the CDW complex order parameter, distributions of the electric field, the density and the current of various normal carriers. A particular challenge was to monitor the local conservation of the condensed and the normal charge densities. That was done easily invoking the chiral invariance and the associated anomaly, but prize is an unconventional Ginsburg-Landau type theory which is not analytic with respect to the order parameter. The numerical modeling poses unusual difficulties but still can demonstrate that vortices are nucleated at the junction boundary when the voltage across, or the current through, exceed a threshold.Comment: To be published in proceedings of the conference SUPERSTRIPES-2014, A. Bianconi ed., J. Supercond. Nov. Mag., (2015

    Genetic polymorphism in meat fatty acids in araucano creole sheeps

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    Meat is a source of proteins and minerals. However, red meats have high levels of saturated fatty acids (SFA) and a low proportion of monounsaturated fatty acids (MUFA), a combination which has been linked to cancer and cardiovascular diseases. In ruminants, there are several genes that regulate the proportions of MUFA in tissues, but the most important is SCD (Stearoyl-CoA desaturase). The polymorphism g.31C >A has been described in the promoter region of the SCD gene, which is associated with changes in the gene expression and MUFA levels in the meat. The aim of this study was to detect the presence of polymorphism g.31C >A in a population of Araucano creole sheep using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism). Genomic DNA was obtained from 157 Araucano creole sheep. The SCD promoter region was amplified using PCR and the amplicons were digested with restriction enzyme MnlI. The allelic frequency was 0.98 for the C allele and 0.02 for the A allele. The in silico analysis showed that the A allele could alter the expression of SCD. This is the first report of the presence of polymorphism g.31C >A in Chilean sheep, and its association with SCD expression levels and the proportion of MUFA in the meat will require further investigation

    Verification of the observer property in discrete event systems

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    The observer property is an important condition to be satisfied by abstractions of Discrete Event System (DES) models. This technical note presents a new algorithm that tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure, called OP-Verifier, can be applied to (potentially nondeterministic) automata, with no restriction on the existence of cycles of 'non-relevant' events. This procedure has quadratic complexity in the number of states. The performance of the algorithm is illustrated by a set of experiments

    Gamma-rays from Type Ia supernova SN2014J

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    The whole set of INTEGRAL observations of type Ia supernova SN2014J, covering the period 19-162 days after the explosion has being analyzed. For spectral fitting the data are split into "early" and "late" periods covering days 19-35 and 50-162, respectively, optimized for 56^{56}Ni and 56^{56}Co lines. As expected for the early period much of the gamma-ray signal is confined to energies below ∌\sim200 keV, while for the late period it is most strong above 400 keV. In particular, in the late period 56^{56}Co lines at 847 and 1248 keV are detected at 4.7 and 4.3 σ\sigma respectively. The lightcurves in several representative energy bands are calculated for the entire period. The resulting spectra and lightcurves are compared with a subset of models. We confirm our previous finding that the gamma-ray data are broadly consistent with the expectations for canonical 1D models, such as delayed detonation or deflagration models for a near-Chandrasekhar mass WD. Late optical spectra (day 136 after the explosion) show rather symmetric Co and Fe lines profiles, suggesting that unless the viewing angle is special, the distribution of radioactive elements is symmetric in the ejecta.Comment: 21 pages, 16 figures, accepted by Ap

    Mathematical Models for Estimating the Risk of vCJD Transmission

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    We present two different simple models for vCJD transmission by blood transfusion. Both models indicate that transfusions alone are unlikely to cause more than a few infections, unless the number of primary cases increases. To improve our models, future work should pursue data collection, empirical estimation of the model parameters, and examination of the underlying assumptions of our frameworks. Further improvements could also include examining susceptibility to vCJD infection by age group and iatrogenic infections introduced through surgical instruments. Regarding the latter, it may be worthwhile to conduct experiments to quantify the transmission of prions from an infected surgical instrument after repeated sterilization procedures

    Are the Models for Type Ia Supernova Progenitors Consistent with the Properties of Supernova Remnants?

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    We explore the relationship between the models for progenitor systems of Type Ia supernovae and the properties of the supernova remnants that evolve after the explosion. Most models for Type Ia progenitors in the single degenerate scenario predict substantial outflows during the presupernova evolution. Expanding on previous work, we estimate the imprint of these outflows on the structure of the circumstellar medium at the time of the supernova explosion, and the effect that this modified circumstellar medium has on the evolution of the ensuing supernova remnant. We compare our simulations with the observational properties of known Type Ia supernova remnants in the Galaxy (Kepler, Tycho, SN 1006), the Large Magellanic Cloud (0509-67.5, 0519-69.0, N103B), and M31 (SN 1885). We find that optically thick outflows from the white dwarf surface (sometimes known as accretion winds) with velocities above 200 km/s excavate large low-density cavities around the progenitors. Such large cavities are incompatible with the dynamics of the forward shock and the X-ray emission from the shocked ejecta in all the Type Ia remnants that we have examined.Comment: To appear in ApJ. 17 pages, 10 figures, emulateap

    Systematically Asymmetric Heliospheric Magnetic Field: Evidence for a Quadrupole Mode and Non-axisymmetry with Polarity Flip-flops

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    Recent studies of the heliospheric magnetic field (HMF) have detected interesting, systematic hemispherical and longitudinal asymmetries which have a profound significance for the understanding of solar magnetic fields. The in situ HMF measurements since 1960s show that the heliospheric current sheet (HCS) is systematically shifted (coned) southward during solar minimum times, leading to the concept of a bashful ballerina. While temporary shifts can be considerably larger, the average HCS shift (coning) angle is a few degrees, less than the 7.2∘7.2^{\circ} tilt of the solar rotation axis. Recent solar observations during the last two solar cycles verify these results and show that the magnetic areas in the northern solar hemisphere are larger and their intensity weaker than in the south during long intervals in the late declining to minimum phase. The multipole expansion reveals a strong quadrupole term which is oppositely directed to the dipole term. These results imply that the Sun has a symmetric quadrupole S0 dynamo mode that oscillates in phase with the dominant dipole A0 mode. Moreover, the heliospheric magnetic field has a strong tendency to produce solar tilts that are roughly opposite in longitudinal phase. This implies is a systematic longitudinal asymmetry and leads to a "flip-flop" type behaviour in the dominant HMF sector whose period is about 3.2 years. This agrees very well with the similar flip-flop period found recently in sunspots, as well as with the observed ratio of three between the activity cycle period and the flip-flop period of sun-like stars. Accordingly, these results require that the solar dynamo includes three modes, A0, S0 and a non-axisymmetric mode. Obviously, these results have a great impact on solar modelling.Comment: 13 pages, 4 figures, Solar Physics, Topical Issue of Space Climate Symposium, in pres

    Effects of dry needling on gait and muscle tone in Parkinson''s disease: a randomized clinical trial

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    Background: Alterations in gait and muscular rigidity are common and disabling in persons with Parkinson''s disease (PD). Objective: The aim of this study was to determine whether a single dry needling (DN) session can promote changes in gait and muscle tone in the lower extremities as well as in the evolution of the disease in persons with PD. Methods: A randomized double-blind clinical trial was designed. Participants were randomly assigned to an intervention group (IG) that received a session of DN over the semitendinosus, medial gastrocnemius, soleus and rectus femoris muscles, or to a control group (CG) that received a session of sham DN in the same muscles. The effects of DN were assessed using the timed up and go test (TUG), 10 meter walk test (10MWT), 6 minute walk test (6MWT) and myotonometry before, immediately after, and 7 days after the intervention. Results: Thirty-three participants were analyzed aged 69.9 +/- 7.2 years (mean +/- SD; 39% female). There were no significant differences between the IG and CG for any outcomes. Significant differences were observed when comparing the Pre and Follow-up values in the IG for functional mobility of gait in the TUG (p = 0.049), gait speed in the 10MWT (p = 0.041) and muscle tone in the lower extremities by myotonometry (frequency (p = 0.027) and stiffness (p = 0.013)). By comparison, there were no significant within-group differences in the CG. Conclusion: A single session of DN had no measurable benefit compared to a single session of sham DN. Within-group changes in the IG suggested improvements in functional mobility of gait and gait speed, as well as changes in the muscle tone in the lower extremities of PD patients, which could be worthy of further exploration by future research

    Motivic Serre invariants, ramification, and the analytic Milnor fiber

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    We show how formal and rigid geometry can be used in the theory of complex singularities, and in particular in the study of the Milnor fibration and the motivic zeta function. We introduce the so-called analytic Milnor fiber associated to the germ of a morphism f from a smooth complex algebraic variety X to the affine line. This analytic Milnor fiber is a smooth rigid variety over the field of Laurent series C((t)). Its etale cohomology coincides with the singular cohomology of the classical topological Milnor fiber of f; the monodromy transformation is given by the Galois action. Moreover, the points on the analytic Milnor fiber are closely related to the motivic zeta function of f, and the arc space of X. We show how the motivic zeta function can be recovered as some kind of Weil zeta function of the formal completion of X along the special fiber of f, and we establish a corresponding Grothendieck trace formula, which relates, in particular, the rational points on the analytic Milnor fiber over finite extensions of C((t)), to the Galois action on its etale cohomology. The general observation is that the arithmetic properties of the analytic Milnor fiber reflect the structure of the singularity of the germ f.Comment: Some minor errors corrected. The original publication is available at http://www.springerlink.co

    Socio-ecology of the Marsh Rice Rat (\u3ci\u3eOryzomys palustris\u3c/i\u3e) and the Spatio-Temporal Distribution of Bayou Virus in Coastal Texas

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    Along the southeastern coast of the United States of America (USA), the marsh rice rat (Oryzomys palustris) is the primary host for the hantavirus genotype Bayou. According to the socio-ecological model for a territorial, polygamous species, females should be distributed across space and time by habitat resources and predation risks, whereas males should space themselves according to the degree of female aggregation and reproductive synchrony. To investigate how females affect the male-male transmission paradigm of Bayou virus, rodents were captured, marked, released, and re-captured in two macrohabitat types across a 30-month period. Microhabitat cover variables were quantified around the individual trap stations. A geodatabase was created from habitat and rodent capture data and analysed in a geographical information system. The ratio of breeding to non-breeding females was ~1:1, with breeding females overly dispersed and non-breeding females randomly dispersed. Spatial analyses revealed both macro- and microhabitat preferences in females. Compared to sero-negatives, higher proportions of seropositive adult males were found consistently within closer proximities to breeding females but not to non-breeding females, indicating that male locations were not driven simply by habitat selection. Activities to acquire dispersed receptive females could be an important driver of Bayou virus transmission among male hosts. To date, socio-ecological theory has received little attention as an investigative framework for studying pathogen dynamics in small, solitary mammals. Herein, we describe an interdisciplinary effort providing a novel approach to elucidate the complexity of hantavirus trafficking and maintenance in rodent populations of a coastal marsh ecosystem
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