Physical implementation of an antimask in URA based coded mask systems

X- and gamma-ray astronomy experiments which employ rectangular URA coded masks alone show artifacts in the images reconstructed due to nonuniform background levels in the detector plane. The employment of a separate antimask in addition to the mask in observations is useful to eliminate this problem. We propose here a method to implement the antimask with the same mask, utilizing the antisymmetric properties in the mask pattern, thereby avoiding the need for a separate antimask in an experiment. Simulations performed with this mask-antimask system are presented to show its advantages.     

Act locally and think globally

Summary A combined approach of molecular dynamics (MD) simulations and the method of real-space Green's function to study properties of complex systems with reduced symmetry is presented. MD simulations provide the equilibrium configuration of the complex system under consideration. The efficiency and flexibility of the method of real-space Green's function allow a detailed examination of any locality of interest. The local analysis based on the combined approach is thus a powerful and convenient tool to study how the interplay between the nature of the local environment and the remaining system affects the properties of the system.     

The effects of kinetic variables on the structure of copper deposits cemented on pure aluminum discs: A scanning electron microscopic study

The structural characteristics of copper deposits resulting from copper cementation on pure aluminum are presented. The effect of chloride ion concentration, rotational speed of the aluminum disc, hydrogen ion concentration, copper ion concentration, and temperature on the nature and morphology of the deposits was investigated. Different copper deposit structures, viz. bulbous, massive crystalline, thick dendrites with leaf-like secondary arms, and dendrites of different degrees of fineness and texture were observed in the present study utilizing the scanning electron microscope. Deposit morphology was greatly modified for variations of chloride ion up to 25 mg l^?1 and for increases in temperature up to 40° C. The maximum rate of copper cementation on pure aluminum was usually associated with a fine, dendritic structure.     

Activated sintering of tungsten alloys through conventional and spark plasma sintering process

The sintering temperature of pure tungsten can be reduced through the addition of small amounts of transition elements. The present study deals with the activated sintering of tungsten with 1.0?wt% additions of copper, cobalt, molybdenum, iron and nickel using the spark plasma sintering (SPS) technique. The alloys were sintered at 1200°C and the mechanical properties and microstructures were compared with those of conventionally sintered alloys, sintered under vacuum condition. The high-rate sintering of SPS has led to an overall reduction in process time and also to a better densification of alloys compared with the conventional sintering process. In both the processes, nickel addition is found to be the best activator, followed by cobalt, iron, molybdenum and copper. The addition of copper and molybdenum showed only a meager increase in the relative density. The alloys, with nickel, cobalt and iron additions, sintered through the SPS process offered much higher density compared with the conventionally sintered alloys. The highest density is observed for the nickel-doped tungsten alloy, which is found to be around 90% of the theoretical density. The microhardness of the sintered alloys is found to depend on its sintered density.     

Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

Densities \((\rho )\) of (0.01 to 0.07) \(\hbox {mol}{\cdot } \hbox {kg}^{-1}\) L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) \(\hbox {mol}{\cdot } \hbox {kg}^{-1}\) solutions have been reported as a function of temperature at \(T = (298.15, 303.15, 308.15\), and 313.15) K and atmospheric pressure. The accurate density \((\rho )\) values are used to estimate the various parameters such as the apparent molar volume \((V_{2,{\upphi }})\), the partial molar volume \((V_{2}^{\infty })\), the isobaric thermal expansion coefficient \((\alpha _{2})\), the partial molar expansion \((E_{2}^{\infty })\), and Hepler’s constant \((\partial ^{2}V_{2}^{\infty }/\partial T^{2})_{P}\). The Cosphere overlap model is used to understand the solute–solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler’s constant \((\partial ^{2}V_{2}^{\infty }/\partial T^{2})_\mathrm{P}\) is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.     

Investigation of polymer dynamics in chitosan-maghemite nanocomposites: a potential green superparamagnetic material

Magnetic composites with superparamagnetic properties have attracted great scientific interest recently. In this article we have investigated chitosan-maghemite (γ-Fe₂O₃) nanocomposite. We have analyzed the effect of temperature and the concentration of maghemite nanoparticles upon the relaxation behaviour of the nanocomposite using Broad band dielectric spectroscopy (BDS). Additionally, various characterization techniques such as X-ray diffraction (XRD), Fourier transform infra red spectra (FTIR), Scanning electron microscopy (SEM), Transmission electron spectroscopy (TEM), Thermo gravimetric Analysis (TGA), Vibrating Sample Magnetometer (VSM), Atomic Force Microscopy (AFM) and Raman spectroscopy have been used for our investigation. Our investigation shows that maghemite nanoparticles interact with chitosan leading to morphological changes in the films and results in modifications in the dielectric and electrical characteristics of the nanocomposite. New relaxations have been identified and their modifications due to maghemite nanoparticles have been investigated. The nanocomposites exhibit superparamagnetic behaviour. This research will benefit research in battery technology and super capacitors.     

A Novel Soft Clustering Approach for Gene Expression Data

Gene expression data represents a condition matrix where each row represents the gene and the column shows the condition. Micro array used to detect gene expression in lab for thousands of gene at a time. Genes encode proteins which in turn will dictate the cell function. The production of messenger RNA along with processing the same are the two main stages involved in the process of gene expression. The biological networks complexity added with the volume of data containing imprecision and outliers increases the challenges in dealing with them. Clustering methods are hence essential to identify the patterns present in massive gene data. Many techniques involve hierarchical, partitioning, grid based, density based, model based and soft clustering approaches for dealing with the gene expression data. Understanding the gene regulation and other useful information from this data can be possible only through effective clustering algorithms. Though many methods are discussed in the literature, we concentrate on providing a soft clustering approach for analyzing the gene expression data. The population elements are grouped based on the fuzziness principle and a degree of membership is assigned to all the elements. An improved Fuzzy clustering by Local Approximation of Memberships (FLAME) is proposed in this work which overcomes the limitations of the other approaches while dealing with the non-linear relationships and provide better segregation of biological functions.     

Device design and optimization of CNTFETs for high-frequency applications

Carbon nanotube (CNT) field-effect transistors (FETs) have recently reached high-frequency (HF) performance similar to that of silicon RF-CMOS at the same gate length despite a tube density and current per tube that are far from the physical limits and suboptimal device architecture. This work reports on an investigation of the optimal device design for practical HF applications in terms of cut-off frequencies, power gain, and linearity. Different fundamental designs in the gate contact arrangement are considered based on a 3D device simulation of both CNTs and contacts. First, unit cells with a single CNT and minimal contact sizes are compared. The resulting simulation data are then extended toward a structure with two gate fingers and realistic contact sizes. Corresponding parasitic capacitances, as well as series and contact resistances, have been included for obtaining realistic characteristics and figures of merit that can be used for comparison with corresponding silicon RF MOSFETs. Finally, a sensitivity analysis of the device architecture with the highest performance is performed in order to find the optimal device design space.

     

Further results on Nakagami-m parameter estimation

Accurate and efficient estimation of fading parameters are of considerable interest in the design of adaptive radios since they provide an indication of the communication link quality. In this letter, we develop a few simple estimators for the Nakagami-m, parameter by approximating the transcendental equations that arise in the computation of maximum-likelihood and generalized moment based estimators as linear of quadratic polynomials using quasinewton optimization method. Statistical properties and efficacy of the new estimators are validated via Monte Carlo simulations.     

Isolation and Identification of Host Cues from Mango, <Emphasis Type="Italic">Mangifera indica</Emphasis>, That Attract Gravid Female Oriental Fruit fly, <Emphasis Type="Italic">Bactrocera dorsalis</Emphasis>

The oriental fruit fly, Bactrocera dorsalis, is an economically damaging, polyphagous pest of fruit crops in South-East Asia and Hawaii, and a quarantine pest in other parts of the world. The objective of our study was to identify new attractants for B. dorsalis from overripe mango fruits. Headspace samples of volatiles were collected from two cultivars of mango, ‘Alphonso’ and ‘Chausa’, and a strong positive behavioral response was observed when female B. dorsalis were exposed to these volatiles in olfactometer bioassays. Coupled GC-EAG with female B. dorsalis revealed 7 compounds from ‘Alphonso’ headspace and 15 compounds from ‘Chausa’ headspace that elicited an EAG response. The EAG-active compounds, from ‘Alphonso’, were identified, using GC-MS, as heptane, myrcene, (Z)-ocimene, (E)-ocimene, allo-ocimene, (Z)-myroxide, and γ-octalactone, with the two ocimene isomers being the dominant compounds. The EAG-active compounds from ‘Chausa’ were 3-hydroxy-2-butanone, 3-methyl-1-butanol, ethyl butanoate, ethyl methacrylate, ethyl crotonate, ethyl tiglate, 1-octen-3-ol, ethyl hexanoate, 3-carene, p-cymene, ethyl sorbate, α-terpinolene, phenyl ethyl alcohol, ethyl octanoate, and benzothiazole. Individual compounds were significantly attractive when a standard dose (1 μg on filter paper) was tested in the olfactometer. Furthermore, synthetic blends with the same concentration and ratio of compounds as in the natural headspace samples were highly attractive (P < 0.001), and in a choice test, fruit flies did not show any preference for the natural samples over the synthetic blends. Results are discussed in relation to developing a lure for female B. dorsalis to bait traps with.