6,462 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
Spacetime Dependent Lagrangians and Weak-Strong Duality : Sine Gordon and Massive Thirring Models
The formalism of spacetime dependent lagrangians developed in Ref.1 is
applied to the Sine Gordon and massive Thirring models.It is shown that the
well-known equivalence of these models (in the context of weak-strong duality)
can be understood in this approach from the same considerations as described in
[1] for electromagnetic duality. A further new result is that all these can be
naturally linked to the fact that the holographic principle has analogues at
length scales much larger than quantum gravity. There is also the possibility
of {\it noncommuting coodinates} residing on the boundaries. PACS: 11.15.-q:
11.10/EfComment: Latex, 16 pages, article shortened, references added, minor typos
correcte
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
Gamma-Gamma Angular Correlation in Sn125
Spin assignment, to the 2.23, 1.98,1.88,1.41 and 1.07 MeV levels of Sb125
has been made from directional angular correlation measurements
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
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
Chemical and kinetic evidence for an essential histidine in horseradish peroxidase for iodide oxidation
Horseradish peroxidase (HRP), when incubated with diethylpyrocarbonate (DEPC), shows a time-dependent loss of iodide oxidation activity. The inactivation follows pseudo-first order kinetics with a second order rate constant of 0.43 min-1 M-1 at 30°C and is reversed by neutralized hydroxylamine. The difference absorption spectrum of the modified versus native enzyme shows a peak at 244 nm, characteristic of N-carbethoxyhistidine, which is diminished by treatment with hydroxylamine. Correlation between the stoichiometry of histidine modification and the extent of inactivation indicates that out of 2 histidine residues modified, one is responsible for inactivation. A plot of the log of the reciprocal half-time of inactivation against log DEPC concentration further suggests that only 1 histidine is involved in catalysis. The rate of inactivation shows a pH dependence with an inflection point at 6.2, indicating histidine derivatization by DEPC. Inactivation due to modification of tyrosine, lysine, or cysteine has been excluded. CD studies reveal no significant change in the protein or heme conformation following DEPC modification. We suggest that a unique histidine residue is required for maximal catalytic activity of HRP for iodide oxidation
The holographic fluid dual to vacuum Einstein gravity
We present an algorithm for systematically reconstructing a solution of the
(d+2)-dimensional vacuum Einstein equations from a (d+1)-dimensional fluid,
extending the non-relativistic hydrodynamic expansion of Bredberg et al in
arXiv:1101.2451 to arbitrary order. The fluid satisfies equations of motion
which are the incompressible Navier-Stokes equations, corrected by specific
higher derivative terms. The uniqueness and regularity of this solution is
established to all orders and explicit results are given for the bulk metric
and the stress tensor of the dual fluid through fifth order in the hydrodynamic
expansion. We establish the validity of a relativistic hydrodynamic description
for the dual fluid, which has the unusual property of having a vanishing
equilibrium energy density. The gravitational results are used to identify
transport coefficients of the dual fluid, which also obeys an interesting and
exact constraint on its stress tensor. We propose novel Lagrangian models which
realise key properties of the holographic fluid.Comment: 31 pages; v2: references added and minor improvements, published
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