Peak Effect in Superconductors: Absence of Phase Transition and Possibility of Jamming in Vortex Matter

The magnetic field $B$ dependence of the critical current $I_c$ for the vortex phase of a disordered superconductor is studied numerically at zero temperature. The $I_{c}(B)$ increases rapidly near the upper critical field $B_{c2}$ similar to the peak effect (PE) phenomenon observed in many superconductors. The real space configuration across the PE changes continuously from a partially ordered domain (polycrystalline) state into an amorphous state. The topological defect density $n_{d}(B)\sim e^{\alpha B^{k}}$ with $k>1$ for $B\geq 0.4B_{c2}$. There is no evidence of a phase transition in the vicinity of the PE suggesting that an order-disorder transition is not essential for the occurrence of the PE phenomenon. An alternative view is presented wherein the vortex system with high dislocation density undergoes jamming at the onset of the PE.Comment: 8 pages and 5 figure

Peak effect in YBCO crystals: Statics and dynamics of the vortex lattice

Oscillatory dynamics and quasi-static Campbell regime of the vortex lattice (VL) in twinned YBa2Cu3O7 single crystals has been explored at low fields near the peak effect (PE) region by linear and non-linear ac susceptibility measurements. We show evidence that the PE is a dynamic anomaly observed in the non-linear response, and is absent in the Labusch constant derived from the linear Campbell regime. Static properties play a major role however, and we identify two H(T) lines defining the onset and the end of the effect. At H1(T) a sudden increase in the curvature of the pinning potential wells with field coincides with the PE onset. At a higher field, H2(T), a sudden increase in linear ac losses, where dissipative forces overcome pinning forces, marks the end of Campbell regime and, simultaneously, the end of the PE anomaly. Vortex dynamics was probed in frequency dependent measurements, and we find that in the PE region, vortex dynamics goes beyond the description of a power law with a finite creep exponent for the constitutive relation.Comment: 8 pages, 5 figure

Thermal conduction and particle transport in strong MHD turbulence, with application to galaxy-cluster plasmas

We investigate field-line separation in strong MHD turbulence analytically and with direct numerical simulations. We find that in the static-magnetic-field approximation the thermal conductivity in galaxy clusters is reduced by a factor of about 5-10 relative to the Spitzer thermal conductivity of a non-magnetized plasma. We also estimate how the thermal conductivity would be affected by efficient turbulent resistivity.Comment: Major revision: higher resolution simulations lead to significantly different conclusions. 26 pages, 10 figure

Convection and AGN Feedback in Clusters of Galaxies

A number of studies have shown that the convective stability criterion for the intracluster medium (ICM) is very different from the Schwarzchild criterion due to the effects of anisotropic thermal conduction and cosmic rays. Building on these studies, we develop a model of the ICM in which a central active galactic nucleus (AGN) accretes hot intracluster plasma at the Bondi rate and produces cosmic rays that cause the ICM to become convectively unstable. The resulting convection heats the intracluster plasma and regulates its temperature and density profiles. By adjusting a single parameter in the model (the size of the cosmic-ray acceleration region), we are able to achieve a good match to the observed density and temperature profiles in a sample of eight clusters. Our results suggest that convection is an important process in cluster cores. An interesting feature of our solutions is that the cooling rate is more sharply peaked about the cluster center than is the convective heating rate. As a result, in several of the clusters in our sample, a compact cooling flow arises in the central region with a size R that is typically a few kpc. The cooling flow matches onto a Bondi flow at smaller radii. The mass accretion rate in the Bondi flow is equal to, and controlled by, the rate at which mass flows in through the cooling flow. Our solutions suggest that the AGN regulates the mass accretion rate in these clusters by controlling R: if the AGN power rises above the equilibrium level, R decreases, the mass accretion rate drops, and the AGN power drops back down to the equilibrium level.Comment: 41 pages, 7 figures, accepted for publication in ApJ. Changes in this version: extended discussion of Bondi accretion in clusters, better mass model, new numerical solution

The effect of antenatal corticosteroids on maternal glycemic control, in a tertiary care centre in North Kerala - India

Background: Antenatal glucocorticoid therapy (ACT) can be life-saving in preterm babies and risk of PTL is increasing in. The prevalence of GDM also increasing. Virtually, all women will experience deterioration in their glycaemic control following ACT. The NICE guideline recommends additional insulin and the national Indian guidelines recommend a 20% increase. Objective of this study was to evaluate the changes in maternal serum glucose following corticosteroids in antenatal women.Methods: Prospective controlled trial of 206 patients, divided into 2 groups. Group 1:105 patients with no GDM and Group 2: 101 patients with GDM. Ethical committee approved. FBS and PPBS measured for following 5 days of D1. BMI and starting dose of insulin and dose of insulin hike were recorded. FBS >90 mg/dL and PPBS >120 mg/dL were taken as abnormal. Data were analyzed using SPSSV22.Results: There were a total of 206 of which 105 were in group 1(51%) and 101(49%) were in Group 2. FBS >90 mg/dL in over 65% of all women on D2 10 new cases on D3 and PPBS >120 mg/dL in over 66% of all women on D2 and 13 new cases on D3. Insulin was started in a total of 66 patients of 105 (62.9%) in Group 1 and 33 out of 40 (82.5%) in GDM on MNT. Of the 66 patients who started on insulin in Group 1, 17 (16.2%) patients had to continue insulin and out of 33. In MNT subgroup 10 (25%) had to continue. BMI was high in the patients, who was given and continued insulin.Conclusions: The findings support the concept of increasing the dose of insulin even before the hyperglycemia documented. In the Group 1 66 of 105 patients were started on insulin due to hyperglycemia and 17 had to continue insulin 25.7%), and 33 of 40 patients in GDM on MNT were started on insulin and 10 (30.33%) had to continue. We suggest testing all patients for hyperglycemia and to start  insulin especially in the those with high BMI (>25 as per the Asian Indian)

Construction of a Plasmodium falciparum Rab-interactome identifies CK1 and PKA as Rab-effector kinases in malaria parasites

Background information The pathology causing stages of the human malaria parasite Plasmodium falciparum reside within red blood cells that are devoid of any regulated transport system. The parasite, therefore, is entirely responsible for mediating vesicular transport within itself and in the infected erythrocyte cytoplasm, and it does so in part via its family of 11 Rab GTPases. Putative functions have been ascribed to Plasmodium Rabs due to their homology with Rabs of yeast, particularly with Saccharomyces that has an equivalent number of rab/ypt genes and where analyses of Ypt function is well characterized. Results Rabs are important regulators of vesicular traffic due to their capacity to recruit specific effectors. In order to identify P. falciparum Rab (PfRab) effectors, we first built a Ypt-interactome by exploiting genetic and physical binding data available at the Saccharomyces genome database (SGD). We then constructed a PfRab-interactome using putative parasite Rab-effectors identified by homology to Ypt-effectors. We demonstrate its potential by wet-bench testing three predictions; that casein kinase-1 (PfCK1) is a specific Rab5B interacting protein and that the catalytic subunit of cAMP-dependent protein kinase A (PfPKA-C) is a PfRab5A and PfRab7 effector. Conclusions The establishment of a shared set of physical Ypt/PfRab-effector proteins sheds light on a core set Plasmodium Rab-interactants shared with yeast. The PfRab-interactome should benefit vesicular trafficking studies in malaria parasites. The recruitment of PfCK1 to PfRab5B+ and PfPKA-C to PfRab5A+ and PfRab7+ vesicles, respectively, suggests that PfRab-recruited kinases potentially play a role in early and late endosome function in malaria parasites

Target Population Environments and Pest Distribution Modelling: An Approach towards Pest Prioritization and Preparedness

The transboundary crop pest and disease (P&D) outbreaks over large geographical regions jeopardizes the food security and have broad economic, social and environmental impacts. The upsurge of new crop P&D, such as fall armyworm; cassava mosaic and brown streak virus; banana fusarium wilt tropical race 4 and wheat stem rust Ug99 are having serious repercussions on agriculture. Climate change is, in part, responsible for food chain catastrophes arising from these transboundary P&D. However, there is clear evidence that climate change impacts are altering the distribution of crop P&D. Such accelerated events require more attention on a greater scale to strengthen food security and protect the livelihoods of poor and most vulnerable countries of the world. A well-defined P&D ranking and distribution will focus on supporting policy-making, integrated P&D management as well as tangible pre-emptive breeding strategies at large scale. Here, we have used chickpea homogenous systems units (HSUs) defined by mechanistic models and geo-bio-physical parameters; over which the P&D distribution and rankings were over-layered. The chickpea P&D severity, distributions, social impact and key drivers responsible for spread on these locations were identified by using meta-analysis. Further, in order to understand the possible risks and consequences of P&D population growth and geographical expansion, the CLIMEX package was used. We aim to compare the pest distribution generic models and prioritization methodologies for emerging regional specific P&D. These findings would support policy intrusions associated with long term transformative adaptation strategies for climate change

Secondary peak on asymmetric magnetization loop of type-II superconductors

Asymmetric magnetization loops with a second peak effect were parameterized by the extended critical state model. The magnetic field distribution in a sample is considered. Expression is suggested for a peak of the critical current density and corresponding depression on field dependence of the depth of surface layer with equilibrium magnetization. These functions determine the width and the asymmetry of a magnetization loop. Asymmetry of the secondary peak height on magnetization branches for increasing and decreasing field is reproduced on the computed magnetization curves.Comment: 6 pages, 2 figures, Equation 6 is modified to be f=0 at B=

Correlation between Oxidative Stress and Thyroid Function in Patients with Nephrotic Syndrome

Background. The present study is to look for a correlation between oxidative stress and thyroid function in patients with the nephrotic syndrome in the remission phase as well as in a persistent proteinuric state. Introduction. Nephrotic syndrome is a form of chronic kidney disease due to which blood loses protein through the urine. We wanted to know if there was an increased loss of thyroid hormones in urine affecting thyroid function. Methods. 60 patients with nephrotic syndrome and 20 healthy non-proteinuric individuals as control subjects were enrolled in the study. We measured their serum tri-iodothyronine, thyroxine and thyroid-stimulating hormone. Estimation of lipid peroxidation (LPx) catalase, superoxide dismutase (SOD), and Glutathione peroxidase (GPx) were carried out by standard methods. Results. TSH was elevated in the nephrotic patients compared to controls, while TT4 and TT3 were significantly lower in the patients than in controls. Lipid Peroxidation and GPx were significantly higher in the nephrotic syndrome patients than in the controls, while SOD and catalase were significantly lower than in patients than in the control subjects. Conclusion. Nephrotic patients can lose significant amounts of thyroid hormones along with protein in urine, which can affect thyroid status, but this is reversible on remission