Numerical computations on one-dimensional inverse scattering problems

An approximate method to determine the index of refraction of a dielectric obstacle is presented. For simplicity one dimensional models of electromagnetic scattering are treated. The governing equations yield a second order boundary value problem, in which the index of refraction appears as a functional parameter. The availability of reflection coefficients yield two additional boundary conditions. The index of refraction by a k-th order spline which can be written as a linear combination of B-splines is approximated. For N distinct reflection coefficients, the resulting N boundary value problems yield a system of N nonlinear equations in N unknowns which are the coefficients of the B-splines

Persistence of RNAi-Mediated Knockdown in Drosophila Complicates Mosaic Analysis Yet Enables Highly Sensitive Lineage Tracing.

RNA interference (RNAi) has emerged as a powerful way of reducing gene function in Drosophila melanogaster tissues. By expressing synthetic short hairpin RNAs (shRNAs) using the Gal4/UAS system, knockdown is efficiently achieved in specific tissues or in clones of marked cells. Here we show that knockdown by shRNAs is so potent and persistent that even transient exposure of cells to shRNAs can reduce gene function in their descendants. When using the FLP-out Gal4 method, in some instances we observed unmarked "shadow RNAi" clones adjacent to Gal4-expressing clones, which may have resulted from brief Gal4 expression following recombination but prior to cell division. Similarly, Gal4 driver lines with dynamic expression patterns can generate shadow RNAi cells after their activity has ceased in those cells. Importantly, these effects can lead to erroneous conclusions regarding the cell autonomy of knockdown phenotypes. We have investigated the basis of this phenomenon and suggested experimental designs for eliminating ambiguities in interpretation. We have also exploited the persistence of shRNA-mediated knockdown to design a sensitive lineage-tracing method, i-TRACE, which is capable of detecting even low levels of past reporter expression. Using i-TRACE, we demonstrate transient infidelities in the expression of some cell-identity markers near compartment boundaries in the wing imaginal disc

Research Alert – A Case Study

This paper describes the SDI service, Research Alert, developed in-house at the Structural Engineering Research Centre (SERC) Library. The library provides print as well as electronic versions of the service. The alert service is provided to other institutions and companies as well. The database contains about 45,000 articles with abstracts

Four-photon interference: a realizable experiment to demonstrate violation of EPR postulates for perfect correlations

Bell's theorem reveals contradictions between the predictions of quantum mechanics and the EPR postulates for a pair of particles only in situations involving imperfect statistical correlations. However, with three or more particles, contradictions emerge even for perfect correlations. We describe an experiment which can be realized in the laboratory, using four-photon entangled states generated by parametric down-conversion, to demonstrate this contradiction at the level of perfect correlations.Comment: publishe

Ferromagnetism and the Effect of Free Charge Carriers on Electric Polarization in Y_2NiMnO_6 Double Perovskite

The double perovskite Y_2NiMnO_6 displays ferromagnetic transition at Tc = 81 K. The ferromagnetic order at low temperature is confirmed by the saturation value of magnetization (M_s) and also, validated by the refined ordered magnetic moment values extracted from neutron powder diffraction data at 10 K. This way, the dominant Mn4+ and Ni2+ cationic ordering is confirmed. The cation-ordered P 21/n nuclear structure is revealed by neutron powder diffraction studies at 300 and 10 K. Analysis of frequency dependent dielectric constant and equivalent circuit analysis of impedance data takes into account the bulk contribution to total dielectric constant. This reveals an anomaly which coincides with the ferromagnetic transition temperature (T_c). Pyrocurrent measurements register a current flow with onset near Tc and a peak at 57 K that shifts with temperature ramp rate. The extrinsic nature of the observed pyrocurrent is established by employing a special protocol measurement. It is realized that the origin is due to re-orientation of electric dipoles created by the free charge carriers and not by spontaneous electric polarization at variance with recently reported magnetism-driven ferroelectricity in this materialComment: Published in Physical Review

Conditional probabilities for a single photon at a beam splitter

Published versio

ESTIMATION OF HEMOGLOBIN A1C USING THE COMPLETE BLOOD COUNT MEASURES IN THE DIAGNOSIS OF DIABETES

  Objective: Diabetes is a metabolic disorder occurring either due to the inadequate secretion of insulin or ineffective utilization of insulin by the body. The study was aimed to identify the variations of the complete blood count (CBC) parameters among the diabetic and normal individuals and to derive an empirical formula to estimate hemoglobin A1c (HbA1c) of an individual using CBC parameters.Methods: A total of 83 subjects (mean age: 52.8±9.0 years) involved in the study, among which 39 (mean age: 49.1±8.8 years) were normal and 44 (mean age: 56±7.8 years) were diabetic. The blood was drawn from the participants and was subjected to CBC analysis using automated hematology analyzer. The stepwise linear regression model was used to determine the empirical formula to estimate HbA1c using the CBC parameters. The Student's t-test was performed to identify the group differences.Results: A negative correlation was observed for Hb (r=−0.35**, p<0.001) and packed cell volume (PCV) (r=−0.23**, p<0.05) against HbA1c. The CBC parameters Hb, erythrocyte sedimentation rate, PCV, red blood cells count, mean corpuscular volume, and mean corpuscular Hb exhibited a statistically significant difference at the level (p<0.05) between the normal and diabetic groups. The empirically derived formula yielded sensitivity, specificity, positive predictive value, negative predictive value, and accuracy measures of 91%, 49%, 67%, 83%, and 71%, respectively, in diagnosing diabetes based on the estimated HbA1c.Conclusion: The empirical formula derived to estimate HbA1c could be useful in the prediction of diabetes with an appreciable accuracy