Study of the long-term evolution of the accretion dynamics of GX 339-4

We study the dynamical behaviour of the galactic black hole source GX 339-4 during 2002-2011 outbursts using RXTE, Swift(XRT), XMM-Newton(PN) archival data. We present the spectral evolution of the source using four outbursts data and discuss their similarities/differences between outbursts. We infer that the second peak in 2002/03 and 2004/05 outbursts can be due to a second instant of triggered instability in the accretion disc due to irradiation from the central X-ray source after peak-I. This propagates in viscous time scale and takes ~80-90 days after peak-I to produce peak-II. This unifies all four outbursts having a long rising time of ~90 days. The dynamical evolution of accretion parameters have been studied by modeling the individual observed spectrum with two-component accretion disc model where a Keplerian accretion disc produces the soft photons and the hard part of the spectrum originates from a hot sub-Keplerian central corona. A generic mathematical model has been proposed to understand the evolution of accretion parameters for sources like GX 339-4 which have longer rising time. Also, the possible differences of physical scenario for outbursts with shorter rising time are also discussed.Comment: Accepted for publication in mnra

Supersymmetric Extension of Galilean Conformal Algebras

The Galilean conformal algebra has recently been realised in the study of the non-relativistic limit of the AdS/CFT conjecture. This was obtained by a systematic parametric group contraction of the parent relativistic conformal field theory. In this paper, we extend the analysis to include supersymmetry. We work at the level of the co-ordinates in superspace to construct the N=1 Super Galilean conformal algebra. One of the interesting outcomes of the analysis is that one is able to naturally extend the finite algebra to an infinite one. This looks structurally similar to the N=1 superconformal algebra in two dimensions, but is different. We also comment on the extension of our construction to cases of higher $N$.Comment: 19 pages; v2: 20 pages, Appendix on OPEs added, other minor changes, references adde

Preparation and Characterization of Nanostructured CaCu2.90 Zn0.10 Ti4O12 Ceramic

Nanostructure CaCu2.90Zn0.10Ti4O12 (CCZTO) electronic ceramic was synthesized by semi‐wet route. The objective of this route is to enable the calcination and sintering processes to go for completion in shorter time and at lower temperature.The samples were characterized by XRD, TEM, SEM and EDX analyses. The crystallite size of the CCZTO ceramic, obtained by XRD using Debye Scherrer formula, range from 38‐74nm which is in good agreement with the particle size observed by TEM analysis. It was observed clearly that the grain size significantly increased with an increase in sintering duration. Dielectric measurements were carried out by LCR meter in the temperature range, 300‐  500K, at few selected frequencies. It was also observed that the dielectric constant and dielectric loss of CCZTO are temperature independent in higher frequency whereas temperature dependent in low frequency region. The ceramics exhibit high dielectric constant of 1.35 x 10 4 at 1 kHz

Molecular aggregation structures into ternary system deca glycerol dioleate/ heptane/water

The phase diagram for the ternary system deca glycerol dioleate(DGD)/heptane/water was established at 25°C. In this phase diagram it was seen that the reverse micellar solution phase extends in its area until the water content reaches 35-45 wt%, at which a liquid crystalline phase begins to appear. On the basis of the experimental results of specific conductivity, viscosity, etc. for the samples containing a definite amount of DGD (0,1 M), and varying relative amounts of heptane and water, the mechanism of the transition of reverse micellar structures to liquid crystalline phase is discussed

A fluorescence anisotropy study of tetramer-dimer equilibrium of λ repressor and its implication for function

Tetramer-dimer equilibrium of λ repressor has been studied by fluorescence anisotropy techniques. We have chosen 1-dimethylamino naphthalene-5-sulfonyl chloride (dansyl chloride)-labeled repressor to study the dissociation-association equilibrium, because of relatively long life-time of the probe (> 10 ns). Polarization of the dansyl-labeled repressor decreases with decreasing protein concentrations in the range of 20 to 0.2 μM. The decrease of anisotropy was shown to be due to reversible dissociation of the protein. Size exclusion high-performance liquid chromatography studies and polyacrylamide gel electrophoresis under native conditions (Ferguson plot) confirmed that at around 20 μM concentrations the repressor exists in predominantly tetrameric form, whereas in lower concentrations it exists in predominantly dimer form. A dissociation constant of 2.3 ± 0.9 μM was estimated in 0.1 M potassium phosphate, pH 8.0, at 25° C. A stoichiometric amount of isolated single operator shifted the tetramer-dimer equilibrium toward the dimer. Increased ionic strength had only a modest effect on the dissociation constant. The thermodynamic constants for the dissociation reaction calculated from the Van't Hoff plot was +26.6 kcal/mol for ΔH and +64.7 e.u. for ΔS. The rotational correlation times derived from isothermal Perrin plot indicated elongated dimers and tetramers

Influence of different land-surface processes on Indian summer monsoon circulation

The impact of different land-surface parameterisation schemes for the simulation of monsoon circulation during a normal monsoon year over India has been analysed. For this purpose, three land-surface parameterisation schemes, the NoaH, the Multi-layer soil model and the Pleim-Xiu were tested using the latest version of the regional model (MM5) of the Pennsylvania State University (PSU)/National Center for Atmospheric Research (NCAR) over the Indian summer monsoon region. With respect to different land-surface parameterisation schemes, latent and sensible heat fluxes and rainfall were estimated over the Indian region. The sensitivity of some monsoon features, such as Somali jet, tropical easterly jet and mean sea level pressure, is discussed. Although some features of the Indian summer monsoon, such as wind and mean sea level pressure, were fairly well-simulated by all three schemes, many differences were seen in the simulation of the typical characteristics of the Indian summer monsoon. It was noticed from the results that the features of the Indian summer monsoon, such as strength of the low-level westerly jet, the cross-equatorial flow and the tropical easterly jet were better simulated by NoaH compared with verification analysis than other land-surface schemes. It was also observed that the distribution of precipitation over India during the peak period of monsoon (July) was better represented with the use of the NoaH scheme than by other schemes

Near room-temperature colossal magnetodielectricity and multiglass properties in partially-disordered La2NiMnO6

We report magnetic, dielectric and magnetodielectric responses of pure monoclinic bulk phase of partially-disordered La2NiMnO6, exhibiting a spectrum of unusual properties and establish that this system intrinsically is a true multiglass with a large magnetodielectric coupling (8-20%) over a wide range of temperatures (150 - 300 K). Specifically, our results establish a unique way to obtain colossal magnetodielectricity, independent of any striction effects, by engineering the asymmetric hopping contribution to the dielectric constant via the tuning of the relative spin orientations between neighboring magnetic ions in a transition metal oxide system. We discuss the role of anti-site (Ni-Mn) disorder in emergence of these unusual properties.Comment: 5 pages, 4 figures, Slightly revised version of previous article in condmat: arXiv:1202.4319v

Scaling of NonOhmic Conduction in Strongly Correlated Systems

A new scaling formalism is used to analyze nonlinear I-V data in the vicinity of metal-insulator transitions (MIT) in five manganite systems. An exponent, called the nonlinearity exponent, and an onset field for nonlinearity, both characteristic of the system under study, are obtained from the analysis. The onset field is found to have an anomalously low value corroborating the theoretically predicted electronically soft phases. The scaling functions above and below the MIT of a polycrystalline sample are found to be the same but with different exponents which are attributed to the distribution of the MIT temperatures. The applicability of the scaling in manganites underlines the universal response of the disordered systems to electric field

Relation of iron stores to oxidative stress in type 2 diabetes

Background: Recent studies revealed elevated serum ferritin levels predict new.onset type 2 diabetes. Further studies proved ferritin to be an important and independent predictor of the development of diabetes. The link between hyperglycemia, enhanced free radical activity (oxidative stress) and serum iron and its stores (serum ferritin levels) levels is not clear.Objectives: The present study is an attempt to understand the relationship between serum ferritin levels and oxidative stress (measured by malondialdehyde).Materials and Methods: The study comprised of 30 apparently healthy controls and 30 type 2 diabetic patients who attended the outpatient and inpatient departments of Medical College, Kolkata. Levels of fasting blood glucose, postprandial blood glucose, serum iron, serum ferritin, glycosylated hemoglobin (HbA1c) and malondialdehyde (MDA), serum urea and creatinine were estimated. The statistical software SPSS 11.0 and Systat 8.0 were used for the analysis of the data and Microsoft Word and Excel have been used to generate tables and graphs.Results: Serum iron (82.16 } 13.24 ƒÊg/dl), serum ferritin (224.53 } 96.06 ƒÊg/L), HbA1c (8.62 } 1.79%), MDA (2.66 } 0.76 nmol/ml) levels were significantly higher in type 2 diabetics compared with apparently healthy controls. Elevations in serum iron, ferritin and HbA1c are accompanied by a parallel increase in blood glucose. Based on groups of glycemic control, i.e. HbA1c levels >8%, serum ferritin levels were highest, 258.63 } 22.67 ƒÊg/dl. There is an inverse correlation of serum ferritin levels to MDA levels in the diabetic cases of longer duration of more than 10 years.Conclusion: Serum ferritin level in the present study is found to be higher in the newly diagnosed cases and lower in those patients suffering from diabetes for more than 10 years. This study probably suggests that serum ferritin can represent either as a pro.oxidant or as an antioxidant in a time.dependent manner.Key words: Oxidative stress, serum ferritin, serum malondialdehyde, type 2 diabetes mellitu

Oxidative stress in diabetic patients with retinopathy

Background: Diabetes mellitus (DM) is known to induce oxidative stress along with deranging various metabolisms; one of the late complications of diabetes mellitus is diabetic retinopathy, which is a leading cause of acquired blindness. Poor glycemic control and oxidative stress have been attributed to the development of complications like diabetic retinopathy. The aim of this study was to analyze and correlate oxidative stress marker, Malondialdehyde (MDA), and antioxidants (erythrocyte glutathione, vitamin C) along with glycosylated hemoglobin (HbA1c) and fasting blood sugar (FBS) in diabetic patients with and without retinopathy.Materials and Methods: The study population comprised of 50 type 2 diabetics with retinopathy as Group 1 (G1) and 50 type 2 diabetics without retinopathy as Group 2 (G2) in the age group 40-70 years as patients, and 50 ageand gender-matched healthy individuals as controls, Group 3 (G3). FBS, HbA1c MDA, glutathione in erythrocytes, and vitamin C were assayed. Results were analyzed using SPSS 11.0, Mann–Whitney U-test, and Pearson correlation coefficient.Results: Mean FBS (mg/dl) were 194.04 ± 48.52 (G1), 181.24 ± 50.05 (G2), and 92.20 ± 9.19 (G3) (P < 0.001). Mean values of MDA were 6.65 ± 0.30 (G1), 4.63 ± 0.56 (G2), and 3.90 ± 0.34 (G3) (P < 0.001). The mean reduced glutathione (GSH) levels were (mg/g of Hb) 6.10 ± 1.41 (G1), 6.44 ± 1.53 (G2), and 13.09 ± 2.49 (G3) (P < 0.001). The mean vitamin C levels (mg/dl) were 0.70 ± 0.24 (G1), 0.87 ± 0.29 (G2), and 1.25 ± 0.27 (G3) (P < 0.001).Conclusion: Estimation of HbA1c, MDA, GSH in erythrocytes, and vitamin C levels can contribute to determine the extent of oxidative stress in diabetes and help in effective control and prevention of the onset and progression of diabetic retinopathy.Keywords: Diabetic retinopathy, glycosylated hemoglobin,  malondialdehyde, reduced glutathione, vitamin