10,006 research outputs found
Reply to Comment on "Dynamical corrections to the DFT-LDA electron conductance in nanoscale systems"
We reply to the comment by Jung, Bokes, and Godby (arXiv:0706.0140) on our
paper Phys. Rev. Lett. 94, 186810 (2005). We show that the results in their
comment should not be taken as an indication that the viscosity corrections to
the conductance of real nanoscale structures are small. A more accurate
treatment of the density and current density distribution and of the electronic
correlations may yield much larger corrections in realistic systems.Comment: Reply to the comment by Jung et al (arXiv:0706.0140). 1 page, no
figures, to appear in PR
Bacterial Source Tracking to Support the Development and Implementation of Watershed Protection Plans for the Lampasas and Leon Rivers: Lampasas River Watershed Final Report
The Bacterial Source Tracking to Support the Development and Implementation of Watershed Protection Plans for the Lampasas and Leon Rivers project was developed to provide supplemental information to stakeholders engaged in the development and implementation of watershed protection plans for each watershed. The Leon River is listed as an impaired water body for elevated levels of E. coli and does not support its designated contact recreation use. The Lampasas River was also considered impaired for elevated E. coli levels until 2010 when it was determined that the data listing the segment no longer met the state’s criteria for assessment. Through the watershed protection planning process, stakeholders in each watershed will use adaptive management to refine management strategies that will mitigate bacteria loading from potential sources of pollution within the watershed
A quantum mechanical insight into SN2 reactions: Semiclassical initial value representation calculations of vibrational features of the Cl--CHCl pre-reaction complex with the VENUS suite of codes
The role of vibrational excitation of reactants in driving reactions
involving polyatomic species has been often studied by means of classical or
quasi-classical trajectory simulations. We propose a different approach based
on investigation of vibrational features of the Cl--CHCl pre-reaction
complex for the Cl + CHCl SN reaction. We present vibrational power
spectra and frequency estimates for the title pre-reaction complex calculated
at the level of classical, semiclassical, and second-order vibrational
perturbation theory on a pre-existing analytical potential energy surface. The
main goals of the paper are the study of anharmonic effects and understanding
of vibrational couplings that permit energy transfer between the collisional
kinetic energy and the internal vibrations of the reactants. We provide both
classical and quantum pictures of intermode couplings and show that the SN2
mechanism is favored by the coupling of a C--Cl bend involving the Cl
projectile with the CH rocking motion of the target molecule. We also
illustrate how the routines needed for semiclassical vibrational spectroscopy
simulations can be interfaced in a user-friendly way to pre-existing molecular
dynamics software. In particular, we present an implementation of semiclassical
spectroscopy into the VENUS suite of codes, thus providing a useful
computational tool for users who are not experts of semiclassical dynamics
Observation of bosonic coalescence of photon pairs
Quantum theory predicts that two indistinguishable photons incident on a
beam-splitter interferometer stick together as they exit the device (the pair
emerges randomly from one port or the other). We use a special
photon-number-resolving energy detector for a direct loophole-free observation
of this quantum-interference phenomenon. Simultaneous measurements from two
such detectors, one at each beam-splitter output port, confirm the absence of
cross-coincidences.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let
Finding Your Literature Match -- A Recommender System
The universe of potentially interesting, searchable literature is expanding
continuously. Besides the normal expansion, there is an additional influx of
literature because of interdisciplinary boundaries becoming more and more
diffuse. Hence, the need for accurate, efficient and intelligent search tools
is bigger than ever. Even with a sophisticated search engine, looking for
information can still result in overwhelming results. An overload of
information has the intrinsic danger of scaring visitors away, and any
organization, for-profit or not-for-profit, in the business of providing
scholarly information wants to capture and keep the attention of its target
audience. Publishers and search engine engineers alike will benefit from a
service that is able to provide visitors with recommendations that closely meet
their interests. Providing visitors with special deals, new options and
highlights may be interesting to a certain degree, but what makes more sense
(especially from a commercial point of view) than to let visitors do most of
the work by the mere action of making choices? Hiring psychics is not an
option, so a technological solution is needed to recommend items that a visitor
is likely to be looking for. In this presentation we will introduce such a
solution and argue that it is practically feasible to incorporate this approach
into a useful addition to any information retrieval system with enough usage.Comment: Contribution to the proceedings of the colloquium Future Professional
Communication in Astronomy II, 13-14 April 2010, Cambridge, Massachusetts. 11
pages, 4 figures
On EPR paradox, Bell's inequalities and experiments which prove nothing
This article shows that the there is no paradox. Violation of Bell's
inequalities should not be identified with a proof of non locality in quantum
mechanics. A number of past experiments is reviewed, and it is concluded that
the experimental results should be re-evaluated. The results of the experiments
with atomic cascade are shown not to contradict the local realism. The article
points out flaws in the experiments with down-converted photons. The
experiments with neutron interferometer on measuring the "contextuality" and
Bell-like inequalities are analyzed, and it is shown that the experimental
results can be explained without such notions. Alternative experiment is
proposed to prove the validity of local realism.Comment: 27 pages, 8 figures. I edited a little the text and abstract I
corrected equations (49) and (50
New 23-phosphodiester derivatives of Silibin and DHS: synthesis and preliminary evaluation of antioxidant properties
Silybin is the major flavonolignan of silymarin which is widely used as a natural remedy for the treatment of cirrhosis, chronic hepatitis, and liver diseases associated with alcohol consumption and exposure to environmental toxins. Different studies recently made on the antiradical activity of silybin and DHS have
elucidated the functional groups responsible for this activity. The results suggest that the C-23 position could be a site for useful modifications aimed to improve the bioactivity of silybin and/or DHS analogues. Recently we describe an efficient synthetic strategy to obtain a variety of new silybin and 2,3-dehydrosilybin (DHS) derivatives in which the 23-hydroxyl group was converted
to a sulfate, phosphodiester, or amine group, using a solution-phase approach.
The antioxidant properties of the new compounds were evaluated in a cellular
model in vivo and most of them displayed an antioxidant activity comparable or
higher to silybin and DHS. These results confirmed the assumption that
modifications in position C–23 do not affect the radical scavenging activity of
these analogues.
With the final goal to expand the repertoire of silybin and DHS C-23 modified,
we describe here the synthesis and preliminary evaluation of antioxidant properties
of a variety of new silybin and DHS conjugated with different labels through a
phosphodiester bond The antioxidative properties of the above-synthesized
compounds were determined by free radical scavenging (DPPH) assay
Dynamic Critical Behavior of the Chayes-Machta Algorithm for the Random-Cluster Model. I. Two Dimensions
We study, via Monte Carlo simulation, the dynamic critical behavior of the
Chayes-Machta dynamics for the Fortuin-Kasteleyn random-cluster model, which
generalizes the Swendsen-Wang dynamics for the q-state Potts ferromagnet to
non-integer q \ge 1. We consider spatial dimension d=2 and 1.25 \le q \le 4 in
steps of 0.25, on lattices up to 1024^2, and obtain estimates for the dynamic
critical exponent z_{CM}. We present evidence that when 1 \le q \lesssim 1.95
the Ossola-Sokal conjecture z_{CM} \ge \beta/\nu is violated, though we also
present plausible fits compatible with this conjecture. We show that the
Li-Sokal bound z_{CM} \ge \alpha/\nu is close to being sharp over the entire
range 1 \le q \le 4, but is probably non-sharp by a power. As a byproduct of
our work, we also obtain evidence concerning the corrections to scaling in
static observables.Comment: LaTeX2e, 75 pages including 26 Postscript figure
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