Retinal Dysplasia Mimicking Retinoblastoma.

Retinal dysplasia represents a congenital disorder characterized by abnormal proliferation of retinal tissue causing leukocoria. We present a case of an infant with bilateral leukocoria, clinically diagnosed as retinoblastoma, followed by enucleation of the left eye. Microscopy however, demonstrated retinal dysplasia consisting of a disorderly proliferation of retinal tissue with formation of rosettes, mimicking retinoblastoma. Microscopic features that aid in differentiating this lesion from retinoblastoma are discussed

Limited Failure Censored Life Test Sampling Plan in Burr Type X Distribution

The Burr type X distribution is considered as a life time random variable of a product whose lots are to be decided for acceptance or otherwise on the basis of sample lifetimes drawn from the lot. The sample is divided into various groups in order to develop a group sampling plan in such a way that the life testing experiment is terminated as soon as the first failure in each group is observed. The acceptance criterion based on the theory of order statistics is proposed and is shown to be more economical than a criterion proposed in the earlier similar works

Black Hole Mass Limits for Optically Dark X-ray Bright Sources in Elliptical Galaxies

Estimation of the black hole mass in bright X-ray sources of nearby galaxies is crucial to the understanding of these systems and their formation. However, the present allowed black hole mass range spans five order of magnitude (10Msun < M < 10^5 Msun) with the upper limit obtained from dynamical friction arguments. We show that the absence of a detectable optical counterpart for some of these sources, can provide a much more stringent upper limit. The argument is based only on the assumption that the outer regions of their accretion disks is a standard one. Moreover, such optically dark X-ray sources cannot be foreground stars or background active galactic nuclei, and hence must be accreting systems residing within their host galaxies. As a demonstration we search for candidates among the point-like X-ray sources detected with Chandra in thirteen nearby elliptical galaxies. We use a novel technique to search for faint optical counterparts in the HST images whereby we subtract the bright galaxy light based on isophotal modeling of the surface brightness. We show that for six sources with no detectable optical emission at the 3$-$sigma level, their black hole masses M_{BH} < 5000Msun. In particular, an ultra-luminous X-ray source (ULX) in NGC 4486 has M_{BH} < 1244 Msun. We discuss the potential of this method to provide stringent constraints on the black hole masses, and the implications on the physical nature of these sources.Comment: 11 Pages, 1 figure, Accepted for publication in Ap

Association of telomere shortening with impaired glucose tolerance and diabetic macroangiopathy

Objective: Shortening of telomere length has been reported in several conditions including Type 2 diabetes and atherosclerosis. The aims of this study were (1) to assess whether telomere shortening occurs at the stage of pre-diabetes, i.e., impaired glucose tolerance (IGT) and (2) whether telomere shortening was greater in Type 2 diabetic subjects with atherosclerotic plaques. Methods: Subjects with impaired glucose tolerance (IGT) (n = 30), non-diabetic control subjects (n = 30), Type 2 diabetic patients without (n = 30) and with atherosclerotic plaques (n = 30) were selected from the Chennai Urban Rural Epidemiology Study (CURES), an ongoing epidemiological population-based study. Southern-blot analysis was used to determine mean terminal restriction fragment (TRF) length, a measure of average telomere size, in leukocyte DNA. Levels of thiobarbituric acid reactive substances (TBARS), protein carbonyl content (PCO) and high sensitive C-reactive protein (hs-CRP) were measured by standard methodologies. Carotid intima-media thickness (IMT) was assessed by high resolution B-mode ultrasonography. Results: The mean (±S.E.) TRF lengths were significantly lower in IGT subjects (6.97 ± 0.3 kb; p = 0.002) and lower still in Type 2 diabetic subjects without plaques (6.21 ± 0.2; p = 0.0001) and lowest in Type 2 diabetic subjects with atherosclerotic plaques (5.39 ± 0.2; p = 0.0001) when compared to control subjects (8.7 ± 0.5). In IGT subjects, TRF length was positively correlated to HDL cholesterol and negatively correlated to glycated hemoglobin (HbA1c), TBARS, PCO, HOMA-IR and IMT. In multiple linear regression analysis, presence of diabetes, HDL cholesterol and increased TBARS levels appear as significant determinants of telomere shortening. Conclusion: Telomere shortening is seen even at the stage of IGT. Among subjects with Type 2 diabetes, those with atherosclerotic plaques had greater shortening of telomere length compared to those without plaques

Estimation and Testing in Type I Generalized Half Logistic Distribution

A generalization of the half logistic distribution is developed through exponentiation of its cumulative distribution function and termed the Type I Generalized Half Logistic Distribution (GHLD). GHLD’s distributional characteristics and parameter estimation using maximum likelihood and modified maximum likelihood methods are presented with comparisons. Comparison of Type I GHLD and the exponential distribution is conducted via likelihood ratio criterion

Stable and Metastable vortex states and the first order transition across the peak effect region in weakly pinned 2H-NbSe_2

The peak effect in weakly pinned superconductors is accompanied by metastable vortex states. Each metastable vortex configuration is characterized by a different critical current density J_c, which mainly depends on the past thermomagnetic history of the superconductor. A recent model [G. Ravikumar, et al, Phys. Rev. B 61, R6479 (2000)] proposed to explain the history dependent J_c postulates a stable state of vortex lattice with a critical current density J_c^{st}, determined uniquely by the field and temperature. In this paper, we present evidence for the existence of the stable state of the vortex lattice in the peak effect region of 2H-NbSe_2. It is shown that this stable state can be reached from any metastable vortex state by cycling the applied field by a small amplitude. The minor magnetization loops obtained by repeated field cycling allow us to determine the pinning and "equilibrium" properties of the stable state of the vortex lattice at a given field and temperature unambiguously. The data imply the occurence of a first order phase transition from an ordered phase to a disordered vortex phase across the peak effect.Comment: 20 pages, 10 figures. Corresponding author: S. Ramakrishna

Growing of Chlorella, Scenedesmus and Botryococus in sewage water for biodiesel production

Algae grown on wastewater media are a potential source of low-​cost lipids for prodn. of liq. biofuels. This study was aimed to est. the effect of Physico-​chem. characteristics of normal and sewage water (pH 7.60 and 6.60, EC 15.97 and 12.36 μmol, free Co2 1.48 and 0.74, nitrogen 0.90 and 0.50 mg​/l, potassium 168.11 and 54.63 mg​/l, calcium 249.52 and 112.21 mg​/l, magnesium 104.91 and 51.19 mg​/l, sulfate 57.08 and 28.35 mg​/l, chloride 98.00 and 84.63 mg​/l, carbonates 362.18 and 32.64 mg​/l and bicarbonates 1138.30 and 253.33 mg​/l in sewage and normal water resp.) on Chlorella, Scenedesmus and Botryococus. The highest biomass (4.533 mg ml-​1)​, chlorophyll (15.56 μg ml-​1)​, lipid (49 %)​, acid value (0.52 mg KOH​/g)​, d. (0.885 g​/cm3)​, iodine value (75 mg​/g)​, sapon. value (0.125 mg KOH​/g)​, viscosity (4.8 mm2​/s)​, myristic acid (9.0​%)​, oleic acid (9.3​%)​, linolenic acid (20.1​%)​, palmitic acid (35.3​%)​, stearic acid (6.1​%) was obsd. in Scenedesmus than Botryococus and Chlorella. The properties of algal oil meet all the properties given by American society for testing and materials (ASTM) D6751, ISO 15607 and EN14214- Europe. Hence, it is concluded that algae can be grown better in sewage water than normal water for their oil and used as a potential feedstock for liq. biofuel prodn