640 research outputs found

    Influence of the Lower Hybrid Drift Instability on the onset of Magnetic Reconnection

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    Two-dimensional and three-dimensional kinetic simulation results reveal the importance of the Lower-Hybrid Drift Instability LHDI to the onset of magnetic reconnection. Both explicit and implicit kinetic simulations show that the LHDI heats electrons anisotropically and increases the peak current density. Linear theory predicts these modifications can increase the growth rate of the tearing instability by almost two orders of magnitude and shift the fastest growing modes to significantly shorter wavelengths. These predictions are confirmed by nonlinear kinetic simulations in which the growth and coalescence of small scale magnetic islands leads to a rapid onset of large scale reconnection

    990-53 Effects on Cardiovascular End Points and Psychological Variables of Metoprolol and Verapamil in Patients with Stable Angina Pectoris — The Angina Prognosis Study in Stockholm (APSIS)

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    The effect of treatment with metoprolol or verapamil was investigated in 809 patients with stable angina pectoris. End points for the study were: death, nonfatal cardiovascular events and three psychological variables reflecting aspects of quality of life. Nonfatal cardiovascular events included acute myocardial infarction, incapacitating or unstable angina, cerebrovascular and peripheral vascular events. The psychological variables were aggregate measures of psychosomatic symptoms and sleep disturbances and an evaluation of life satisfaction on a visual analogue scale. The mean age of the patients was 59±7 years and 30% were women. The patients were followed for a total of 2887 patient years, with a median follow-up time of 3.6 years. Total cardiovascular mortality in the metoprolol versus verapamit group were 5.4% versus 6.2% and 4.7% versus 4.7% respectively. Nonfatal cardiovascular events occurred in 26.4 and 24.1%, respectively. Psychosomatic symptoms and sleep disturbances were significantly improved in both treatment groups. The magnitude of change was small and not significantly different. Life satisfaction did not change on either drug. Withdrawals due to side effects occurred in 11.1 and 14.6%, respectively.ConclusionThis large scale long term study shows that both drugs were well tolerated and had the same effect on mortality, cardiovascular end points and measures of quality of life

    Cosmic Ray Acceleration by Spiral Shocks in the Galactic Wind

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    Cosmic ray acceleration by shocks related with Slipping Interaction Regions (SIRs) in the Galactic Wind is considered. SIRs are similar to Solar Wind Corotating Interaction Regions. The spiral structure of our Galaxy results in a strong nonuniformity of the Galactic Wind flow and in SIR formation at distances of 50 to 100 kpc. SIRs are not corotating with the gas and magnetic field because the angular velocity of the spiral pattern differs from that of the Galactic rotation. It is shown that the collective reacceleration of the cosmic ray particles with charge ZeZe in the resulting shock ensemble can explain the observable cosmic ray spectrum beyond the "knee" up to energies of the order of 1017Z10^{17}Z eV. For the reaccelerated particles the Galactic Wind termination shock acts as a reflecting boundary.Comment: LATEX, 14 pages, 7 figures, accepted to A&

    Three-Dimensional Fermi Surface of Overdoped La-Based Cuprates

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    We present a soft x-ray angle-resolved photoemission spectroscopy study of the overdoped high-temperature superconductors La2−x_{2-x}Srx_xCuO4_4 and La1.8−x_{1.8-x}Eu0.2_{0.2}Srx_xCuO4_4. In-plane and out-of-plane components of the Fermi surface are mapped by varying the photoemission angle and the incident photon energy. No kzk_z dispersion is observed along the nodal direction, whereas a significant antinodal kzk_z dispersion is identified. Based on a tight-binding parametrization, we discuss the implications for the density of states near the van-Hove singularity. Our results suggest that the large electronic specific heat found in overdoped La2−x_{2-x}Srx_xCuO4_4 can not be assigned to the van-Hove singularity alone. We therefore propose quantum criticality induced by a collapsing pseudogap phase as a plausible explanation for observed enhancement of electronic specific heat

    Neutron powder diffraction study of NaMn2_2O4_4 and Li0.92_{0.92}Mn2_2O4_4: New insights on spin-charge-orbital ordering

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    The high-pressure synthesized quasi-one-dimensional compounds NaMn2_2O4_4 and Li0.92_{0.92}Mn2_2O4_4 are both antiferromagnetic insulators, and here their atomic and magnetic structures were investigated using neutron powder diffraction. The present crystal structural analyses of NaMn2O4 reveal that Mn3+/Mn4+ charge-ordering state exist even at low temperature (down to 1.5 K). It is evident from one of the Mn sites shows a strongly distorted Mn3+ octahedra due to the Jahn-Teller effect. Above TN = 39 K, a two-dimensional short-range correlation is observed, as indicated by an asymmetric diffuse scattering. Below TN, two antiferromagnetic transitions are observed (i) a commensurate long-range Mn3+ spin ordering below 39 K, and (ii) an incommensurate Mn4+ spin ordering below 10 K. The commensurate magnetic structure (kC = 0.5, -0.5, 0.5) follows the magnetic anisotropy of the local easy axes of Mn3+, while the incommensurate one shows a spin-density-wave order with kIC = (0,0,0.216). For Li0.92_{0.92}Mn2_2O4_4, on the other hand, absence of a long-range spin ordered state down to 1.5 K is confirmed.Comment: 11 pages, 8 figure

    Heterogeneity after harmonisation: a retrospective cohort study of bleeding and stroke risk after the introduction of direct oral anticoagulants in four Western European countries

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    Purpose: Database heterogeneity can impact effect estimates. Harmonisation provided by common protocols and common data models (CDMs) can increase the validity of pharmacoepidemiologic research. In a case study measuring the changes in the safety and effectiveness of stroke prevention therapy after the introduction of direct oral anticoagulants (DOACs), we performed an international comparison. Methods: Using data from Stockholm, Denmark, Scotland and Norway, harmonised with a common protocol and CDM, two calendar-based cohorts were created: 2012 and 2017. Patients with a diagnosis code of atrial fibrillation 5 years preceding the 1-year cohort window were included. DOAC, vitamin K antagonist and aspirin treatment were assessed in the 6 months prior to the start of each year while strokes and bleeds were assessed during the year. A Poisson regression generated incidence rate ratios (IRRs) to compare outcomes from 2017 to 2012 adjusted for changes in individual-level baseline characteristics. Results: In 280 359 patients in the 2012 cohort and 356 779 in the 2017 cohort, treatment with OACs increased on average from 45% to 65%, while treatment with aspirin decreased from 30% to 10%. In all countries except Scotland, there were decreases in the risk of stroke and no changes in bleeding risk, after adjustment for changes in baseline characteristics. In Scotland, major bleeding (IRR 1.09, 95% confidence interval [CI] [1.00; 1.18]) and intracranial haemorrhage (IRR 1.31, 95% CI [1.13; 1.52]) increased from 2012 to 2017. Conclusions: Stroke prevention therapy improved from 2012 to 2017 with a corresponding reduction in stroke risk without increasing the risk of bleeding in all countries, except Scotland. The heterogeneity that remains after methodological harmonisation can be informative of the underlying population and database

    InParanoid 7: new algorithms and tools for eukaryotic orthology analysis

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    The InParanoid project gathers proteomes of completely sequenced eukaryotic species plus Escherichia coli and calculates pairwise ortholog relationships among them. The new release 7.0 of the database has grown by an order of magnitude over the previous version and now includes 100 species and their collective 1.3 million proteins organized into 42.7 million pairwise ortholog groups. The InParanoid algorithm itself has been revised and is now both more specific and sensitive. Based on results from our recent benchmarking of low-complexity filters in homology assignment, a two-pass BLAST approach was developed that makes use of high-precision compositional score matrix adjustment, but avoids the alignment truncation that sometimes follows. We have also updated the InParanoid web site (http://InParanoid.sbc.su.se). Several features have been added, the response times have been improved and the site now sports a new, clearer look. As the number of ortholog databases has grown, it has become difficult to compare among these resources due to a lack of standardized source data and incompatible representations of ortholog relationships. To facilitate data exchange and comparisons among ortholog databases, we have developed and are making available two XML schemas: SeqXML for the input sequences and OrthoXML for the output ortholog clusters

    Magnetism and Ion Diffusion in Honeycomb Layered Oxide K2_2Ni2_2TeO6_6: First Time Study by Muon Spin Rotation & Neutron Scattering

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    In the quest of finding novel and efficient batteries, a great interest has raised in K-based honeycomb layer oxide materials both for their fundamental properties and potential applications. A key issue in the realization of efficient batteries based on such compounds, is to understand the K-ion diffusion mechanism. However, investigation of potassium-ion (K+^+) dynamics in materials using magneto-spin properties has so far been challenging, due to its inherently weak nuclear magnetic moment, in contrast to other alkali ions such as lithium and sodium. Spin-polarised muons, having a high gyromagnetic ratio, make the muon spin rotation and relaxation (Ό\mu+SR) technique ideal for probing ions dynamics in weak magneto-spin moment materials. Here we report the magnetic properties and K+ dynamics in honeycomb layered oxide material of the K2_2Ni2_2TeO6_6 using Ό\mu+SR measurements. Our low-temperature Ό\mu+SR results together with, with complementary magnetic susceptibility, find an antiferromagnetic transition at 26 K. Further Ό\mu+SR studies performed at higher temperatures reveal that potassium ions (K+^+) become mobile above 250 K and the activation energy for the diffusion process is Ea = 121(13) meV. This is the first time that K+ dynamics in potassium-based battery materials has been measured using Ό\mu+SR. Finally our results also indicate an interesting possibility that K-ion self diffusion occurs predominantly at the surface of the powder particles. This opens future possibilities for improving ion diffusion and device performance using nano-structuring.Comment: 12 pages, 12 figure
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