9,204 research outputs found
Effect of Epitaxial Strain on Phase Separation in Thin Films
We examine the role of an imposed epitaxial strain e in enhancing or
depressing the spinodal instability of an alloy thin film. Since the alloy film
starts with an imposed strain, phase separation offers a mechanism to relieve
it, but only when the film is elastically inhomogeneous. With
composition-dependence of elastic modulus given by y, and that of lattice
parameter by {\eta}, our simulations using the Cahn-Hilliard model show (and
analytical results for early stages confirm) that, for (ey/{\eta}) > 0, the
imposed strain adds to the driving force for phase separation, decreases the
maximally growing wave length, and expands the coherent spinodal in the phase
diagram. Further, when (ey/{\eta}) > 0.372, it expands to even outside of
chemical spinodal. Phase separation produces islands of elastically softer
(harder) phase with (without) a favorable imposed strain. These results are in
agreement with experimental results in GeSi thin films on Si and Ge substrates,
as well as in InGaAs films on GaAs substrates.Comment: 4 pages, 3 figure
Effect of Fibonacci Modulation On Superconductivity
We have studied finite-sized single band models with short range pairing
interactions between electrons in presence of diagonal Fibonacci modulation in
one dimension. Two models, namely the attractive Hubbard model and the
Penson-Kolb model, have been investigated at half-filling at zero temperature
by solving the Bogoliubov-de Gennes equations in real space within a mean field
approximation. The competition between ``disorder'' and the pairing interaction
leads to a suppression of superconductivity (of usual pairs with zero
centre-of-mass momenta) in the strong-coupling limit while an enhancement of
the pairing correlation is observed in the weak-coupling regime for both the
models. However, the dissimilarity of the pairing mechanisms in these two
models brings about notable difference in the results. The extent to which the
bond ordered wave and the -paired (of pairs with centre-of-mass momenta =
) phases of the Penson-Kolb model are affected by the disorder has also
been studied in the present calculation. Some finite size effects are also
identified.Comment: 14 pages, 13 figure
Anemia in Antiretroviral Naïve HIV/AIDS Patients: A Study from Eastern India
Background: Hematological manifestations are common throughout the course of HIV infection. Impact of anemia is the most significant among them. The present study was undertaken to evaluate the etiologies underlying anemia in HIV/AIDS. Methods This was a non randomized cross sectional observational study conducted in a tertiary care hospital of India over a period of 2 years. One hundred and fifty HIV patients were screened. Thorough clinical and laboratory evaluation was done in 50 randomly selected anemic cases. Results: Proper etiological diagnosis could be reached in 46 patients. Among them correlation between Hb% and CD4 count was statistically insignificant (p = 0.074, r = 0.47) whereas it was significant with absolute lymphocyte and CD4 count (p = 0.006, r = 0.41). There was better correlation of bone marrow iron status with percent saturation of transferrin (p = 0.003, r = 0.54) than with serum ferritin (p = 0.055, r = 0.09). Bone marrow iron status did not have any relationship with CD4 count. Anemia of chronic disease was the commonest etiology (37%) followed by HIV related myelodysplastic syndrome (31%), iron deficiency anemia (13%), bone marrow suppression due to direct involvement by some infective process (7%). Aplastic anemia, multiple myeloma, Hodgkin’s disease, pure red cell aplasia, hemophagocytic lymphohistiocytosis and vitamin B12 deficiency were detected in one case (2%) each. Conclusions: Etiologies of anemia in HIV/AIDS are multifactorial with anemia of chronic disease being the commonest. For screening of iron deficiency in this group, percent saturation is a better tool than serum ferritin. Absolute lymphocyte count can sometimes be used as a surrogate marker of immunological status in antiretroviral naïve HIV patients, particularly in resource poor areas
Unconventional superconductivity in the cage type compound ScRhSn
We have examined the superconducting ground state properties of the caged
type compound ScRhSn using magnetization, heat capacity, and
muon-spin relaxation or rotation (SR) measurements. Magnetization
measurements indicate type-II superconductivity with an upper critical field
= 7.24 T. The zero-field cooled and field cooled
susceptibility measurements unveil an onset of diamagnetic signal below = 4.4 K. The interpretation of the heat capacity results below
using the BCS model unveils the value of = 2.65, which gives
the dimensionless ratio 2 = 5.3, intimating that
ScRhSn is a strong-coupling BCS superconductor. The zero-field
SR measurements in the longitudinal geometry exhibit a signature of a
spontaneous appearance of the internal magnetic field below the superconducting
transition temperature, indicating that the superconducting state is
characterized by the broken time-reversal symmetry (TRS). We have compared the
results of broken TRS in ScRhSn with that observed in
RRhSn (R = Lu and Y).Comment: 6 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1411.687
Local and global statistical distances are equivalent on pure states
The statistical distance between pure quantum states is obtained by finding a
measurement that is optimal in a sense defined by Wootters. As such, one may
expect that the statistical distance will turn out to be different if the set
of possible measurements is restricted in some way. It nonetheless turns out
that if the restriction is to local operations and classical communication
(LOCC) on any multipartite system, then the statistical distance is the same as
it is without restriction, being equal to the angle between the states in
Hilbert space.Comment: 5 pages, comments welcom
Flux-density spectral analysis for several pulsars and two newly-identified gigahertz-peaked spectra
In this paper we present results from flux density measurements for 21
pulsars over a wide frequency range, using the Giant Metrewave Radio Telescope
(GMRT) and the Effelsberg telescope. Our sample was a set of mostly newly
discovered pulsars from the selection of candidates for gigahertz-peaked
spectra (GPS) pulsars. Using the results of our observations along with
previously published data, we identify two new GPS pulsars. One of them, PSR
J1740+1000, with dispersion measure of 24 pc cm, is the first GPS pulsar
with such a low DM value.We also selected several strong candidates for objects
with high frequency turnover in their spectra which require further
investigation.We also revisit our source selection criteria for future searches
for GPS pulsars.Comment: 10 pages, 2 tables, 9 figures, accepted for publication in MNRA
Baryon Inhomogeneity Generation in the Quark-Gluon Plasma Phase
We discuss the possibility of generation of baryon inhomogeneities in a
quark-gluon plasma phase due to moving Z(3) interfaces. By modeling the
dependence of effective mass of the quarks on the Polyakov loop order
parameter, we study the reflection of quarks from collapsing Z(3) interfaces
and estimate resulting baryon inhomogeneities in the context of the early
universe. We argue that in the context of certain low energy scale inflationary
models, it is possible that large Z(3) walls arise at the end of the reheating
stage. Collapse of such walls could lead to baryon inhomogeneities which may be
separated by large distances near the QCD scale. Importantly, the generation of
these inhomogeneities is insensitive to the order, or even the existence, of
the quark-hadron phase transition. We also briefly discuss the possibility of
formation of quark nuggets in this model, as well as baryon inhomogeneity
generation in relativistic heavy-ion collisions.Comment: 11 pages, 2 figures, revtex4, more detailed discussion added about
formation and evolution of Z(3)domain walls in the univers
Effect of silver on the phase transition and wettability of titanium oxide films
The effect of silver on the phase transition and microstructure of titanium oxide films grown by pulsed cathodic arc had been investigated by XRD, SEM and Raman spectroscopy. Following successive thermal annealing up to 1000 °C, microstructural analysis of annealed Ag-TiO2 films reveals that the incorporation of Ag nanoparticles strongly affects the transition temperature from the initial metastable amorphous phase to anatase and stable rutile phase. An increase of silver content into TiO2 matrix inhibits the amorphous to anatase phase transition, raising its temperature boundary and, simultaneously reduces the transition temperature to promote rutile structure at lower value of 600 °C. The results are interpreted in terms of the steric effects produced by agglomeration of Ag atoms into larger clusters following annealing which hinders diffusion of Ti and O ions for anatase formation and constrains the volume available for the anatase lattice, thus disrupting its structure to form rutile phase. The effect of silver on the optical and wetting properties of TiO2 was evaluated to demonstrate its improved photocatalytic performance
Constraints on R-parity violating supersymmetry from neutral meson mixing
Upper bounds at the weak scale are put on all
type products of R-parity violating supersymmetry that may affect K-Kbar and
B-Bbar mixing. We constrain all possible products, including some not
considered before, using next-to-leading order QCD corrections to the mixing
amplitudes. Constraints are obtained for both real and imaginary parts of the
couplings. We also discuss briefly some correlated decay channels which should
be investigated in future experiments.Comment: 13 pages, 2 figures, uses revtex. Constraints updated, and new
constraints adde
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