6,285 research outputs found
Demonstration of a 1/4 cycle phase shift in the radiation-induced oscillatory-magnetoresistance in GaAs/AlGaAs devices
We examine the phase and the period of the radiation-induced
oscillatory-magnetoresistance in GaAs/AlGaAs devices utilizing in-situ magnetic
field calibration by Electron Spin Resonance of DiPhenyl-Picryl-Hydrazal. The
results confirm a -independent 1/4 cycle phase shift with respect to the condition for , and they also suggest a small
( 2%) reduction in the effective mass ratio, , with respect
to the standard value for GaAs/AlGaAs devices.Comment: 4 pages, 4 color figure
Increased sample asymmetry and memory of cardiac time-series following endotoxin administration in cirrhotic rats
Sepsis, and other causes of acute systemic inflammation, can reduce heart rate variability (HRV) and increase cardiac cycle regularity in mammals. Thus, HRV monitoring has been used for early detection of sepsis in adults and neonates. Liver cirrhosis is associated with reduced basal HRV and the development of tolerance to the cardiac chronotropic effects of bacterial endotoxin. This may pose limitations on the use of heart rate monitoring in early detection of sepsis in this patient population. In a study to develop a physiomarker for the detection of sepsis in cirrhosis, we observed that endotoxin administration in adult cirrhotic rats leads to the development of transient heart rate decelerations, a phenomenon which has been reported in neonates with sepsis, and quantified using sample asymmetry analysis. In the present study, cirrhosis was induced by surgical ligation of the bile duct in rats. Cirrhotic rats were given intraperitoneal injections of either saline or endotoxin (1 mg kg(-1)). Changes in sample asymmetry and memory length of cardiac time-series were studied in conscious rats using implanted telemetric probes. Cirrhotic (but not control) rats exhibited increased sample asymmetry following endotoxin injection, which was consistent with the development of transient heart rate deceleration. Endotoxin administration in cirrhotic rats was associated with prolongation of memory length for observing decelerating perturbations in the cardiac rhythm. These findings may have application in the development of an HRV monitoring system for early detection of sepsis in cirrhosis
Study of antioxidant enzymes activity during rooting in Adhatoda Vasica under different triazole compounds
Medicinally important plant species, Adhatoda vasica belonging to the family Acanthaceae was selected for the present investigation in order to study the comparative effects of traditional as well as non-traditional growth regulators. The traditional growth regulator selected was IBA and non-traditional one was Hexaconazole and triadimefon. Antioxidant enzymes activities like SOD, APX and CAT were estimated from control as well as treated plants. The activities of antioxidant enzymes like SOD, APX and CAT were increased with TDM, HEX and IBA treatments in Adhatoda vasica plants. The enhancement was significant on all sampling days. These preliminary results prove TDM and HEX as potential growth regulators which can be used to enhance the antioxidant properties of Adhatoda vasica, thereby make it an economically valuable medicinal plant
Investigation of a Parabolic Iterative Solver for Three-dimensional Configurations
A parabolic iterative solution procedure is investigated that seeks to extend the parabolic approximation used within the internal propagation module of the duct noise propagation and radiation code CDUCT-LaRC. The governing convected Helmholtz equation is split into a set of coupled equations governing propagation in the positive and negative directions. The proposed method utilizes an iterative procedure to solve the coupled equations in an attempt to account for possible reflections from internal bifurcations, impedance discontinuities, and duct terminations. A geometry consistent with the NASA Langley Curved Duct Test Rig is considered and the effects of acoustic treatment and non-anechoic termination are included. Two numerical implementations are studied and preliminary results indicate that improved accuracy in predicted amplitude and phase can be obtained for modes at a cut-off ratio of 1.7. Further predictions for modes at a cut-off ratio of 1.1 show improvement in predicted phase at the expense of increased amplitude error. Possible methods of improvement are suggested based on analytic and numerical analysis. It is hoped that coupling the parabolic iterative approach with less efficient, high fidelity finite element approaches will ultimately provide the capability to perform efficient, higher fidelity acoustic calculations within complex 3-D geometries for impedance eduction and noise propagation and radiation predictions
Sub-linear radiation power dependence of photo-excited resistance oscillations in two-dimensional electron systems
We find that the amplitude of the radiation-induced
magnetoresistance oscillations in GaAs/AlGaAs system grows nonlinearly as where is the amplitude and the exponent .
%, with in %the low temperature limit. This striking
result can be explained with the radiation-driven electron orbits model, which
suggests that the amplitude of resistance oscillations depends linearly on the
radiation electric field, and therefore on the square root of the power, .
We also study how this sub-linear power law varies with lattice temperature and
radiation frequency.Comment: 5 pages, 3 figure
Relativistic coupled-cluster calculations of Ne, Ar, Kr and Xe: correlation energies and dipole polarizabilities
We have carried out a detailed and systematic study of the correlation
energies of inert gas atoms Ne, Ar, Kr and Xe using relativistic many-body
perturbation theory and relativistic coupled-cluster theory. In the
relativistic coupled-cluster calculations, we implement perturbative triples
and include these in the correlation energy calculations. We then calculate the
dipole polarizability of the ground states using perturbed coupled-cluster
theory.Comment: 10 figures, 6 tables, submitted to PR
Face Recognition Using Discrete Cosine Transform for Global and Local Features
Face Recognition using Discrete Cosine Transform (DCT) for Local and Global
Features involves recognizing the corresponding face image from the database.
The face image obtained from the user is cropped such that only the frontal
face image is extracted, eliminating the background. The image is restricted to
a size of 128 x 128 pixels. All images in the database are gray level images.
DCT is applied to the entire image. This gives DCT coefficients, which are
global features. Local features such as eyes, nose and mouth are also extracted
and DCT is applied to these features. Depending upon the recognition rate
obtained for each feature, they are given weightage and then combined. Both
local and global features are used for comparison. By comparing the ranks for
global and local features, the false acceptance rate for DCT can be minimized.Comment: face recognition; biometrics; person identification; authentication;
discrete cosine transform; DCT; global local features; Proceedings of the
2011 International Conference on Recent Advancements in Electrical,
Electronics and Control Engineering (IConRAEeCE) IEEE Xplore: CFP1153R-ART;
ISBN: 978-1-4577-2149-
Fock space relativistic coupled-Cluster calculations of Two-Valence Atoms
We have developed an all particle Fock-space relativistic coupled-cluster
method for two-valence atomic systems. We then describe a scheme to employ the
coupled-cluster wave function to calculate atomic properties. Based on these
developments we calculate the excitation energies, magnetic hyperfine constants
and electric dipole matrix elements of Sr, Ba and Yb. Further more, we
calculate the electric quadrupole HFS constants and the electric dipole matrix
elements of Sr, Ba and Yb. For these we use the one-valence
coupled-cluster wave functions obtained as an intermediate in the two-valence
calculations. We also calculate the magnetic dipole hyperfine constants of
Yb.Comment: 23 pages, 12 figures, 10 tables typos are corrected and some minor
modifications in some of the section
A note on the influence of axial velocity ratio on cascade performance
A thin airfoil quasi-two-dimensional potential flow theory has been used to analyze cascades with axial-flow contraction. Attention is centered on the flow turning of a lattice of foils as measured by the deviation angle. The influence of both axial-flow acceleration and foil thickness on the deviation angle is summarized in plots that should be useful for design purposes. It is shown that the effect of axial-flow contraction is larger when the foils are relatively far apart than when they are close together. The influence of axial velocity ratio across the cascade changes markedly with the stagger angle. These effects are essentially unaltered due to foil thickness
- …