7,235 research outputs found
Energy dependent wavelength of the ion induced nanoscale ripple
Wavelength variation of ion beam induced nanoscale ripple structure has
received much attention recently due to its possible application in
nanotechnology. We present here results of Ar bombarded Si in the energy
range 50 to 140 keV to demonstrate that with beam scanning the ripple
wavelength increases with ion energy and decreases with energy for irradiation
without ion beam scanning. An expression for the energy dependence of ripple
wavelength is proposed taking into simultaneous effect of thermally activated
surface diffusion and ion induced effective surface diffusion.Comment: REVTeX (4 pages), 3 EPS figure
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
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
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
Momentum dependence of drag coefficients and heavy flavour suppression in quark gluon plasma
The momentum dependence of the drag coefficient of heavy quarks propagating
through quark gluon plasma (QGP) has been evaluated. The results have been used
to estimate the nuclear suppression factor of charm and bottom quarks in QGP.
We observe that the momentum dependence of the transport coefficients plays
crucial role in the suppression of the heavy quarks and consequently in
discerning the properties of QGP using heavy flavours as a probe. We show that
the large suppression of the heavy quarks observed at RHIC and LHC is
predominantly due to the radiative losses. The suppression of in Pb+Pb
collisions at LHC energy - recently measured by the ALICE collaboration has
also been studied.Comment: Minor changes in the tex
Bounds on R-parity violating SUSY Yukawa couplings from semileptonic decays of baryons
We consider tree-level corrections to hypercharge changing semileptonic
decays of certain baryons induced by a minimal supersymmetric standard model
with explicitly broken R-parity via -violation. This study leads to a new
set of constraints on the products of couplings arising from the LQd
operator of the superpotential.Comment: Latex (8 pages), no figur
Exploration of the psychological impact and adaptation to cardiac events in South Asians in the UK: a qualitative study.
OBJECTIVE: There is little research on how different ethnic groups adapt after an acute cardiac event. This qualitative study explores between-ethnicity and within-ethnicity variation in adaptation, and the psychological impact of an acute cardiac event among UK South Asian and white British people.
SETTING: We purposively sampled people by ethnic group from general practices in London who had a new myocardial infarction, angina or acute arrhythmia in the preceding 18 months.
PARTICIPANTS: We conducted 28 semistructured interviews for exploring the psychological symptoms, experiences and adaptations following a cardiac event among South Asians (Indian and Bangladeshi) in comparison to white British people. Data were analysed using a thematic 'framework' approach.
RESULTS: Findings showed heterogeneity in experiences of the cardiac event and its subsequent psychological and physical impact. Adaptation to the event related predominantly to life circumstances, personal attitudes and employment status. Anxiety and low mood symptoms were common sequelae, especially in the Bangladeshi group. Indian men tended to normalise symptoms and the cardiac event, and reported less negative mood symptoms than other groups. Fear of physical exertion, particularly heavy lifting, persisted across the groups. Some people across all ethnic groups indicated the need for more psychological therapy postcardiac event. Socioeconomic circumstances, age and prior work status appeared to be more important in relation to adaptation after a cardiac event than ethnic status.
CONCLUSIONS: Heterogeneity in views and experiences related to the socioeconomic background, age and work status of the participants along with some cultural influences. Rehabilitation programmes should be flexibly tailored for individuals in particular and where relevant, specific support should be provided for returning to work
Mesonic Excitations of QGP: Study with an Effective Model
We study the correlations between quark-antiquark pairs in different quantum
number channels in a deconfined plasma by using an effective model of QCD.
Using the three flavour PNJL model, the finite temperature spectral functions
for different mesonic states are studied at zero and nonzero quark chemical
potentials. It is found that in the channel resonance structures survive
above the chiral transition temperature \tc, while the kaonic states seem to
get washed off just above \tc. The sensitivity of the structures to the
anomaly term are carefully investigated.Comment: 15page
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