361 research outputs found
Jurek Becker: Five Stories
David Rock, ed. New York: St. Martin\u27s Press, 1993. 168 p
Jurek Becker: Jacob the Liar
Leila Vennewitz, trans. New York: Arcade Publishing, 1996. 244 p
Susan M. Johnson: The Works of Jurek Becker: A Thematic Analysis
New York: Peter Lang, 1988. 214 p
Electrostatic solvation free energies of charged hard spheres using molecular dynamics with density functional theory interactions
Determining the solvation free energies of single ions in water is one of the
most fundamental problems in physical chemistry and yet many unresolved
questions remain. In particular, the ability to decompose the solvation free
energy into simple and intuitive contributions will have important implications
for models of electrolyte solution. Here, we provide definitions of the various
types of single ion solvation free energies based on different simulation
protocols. We calculate solvation free energies of charged hard spheres using
density functional theory interaction potentials with molecular dynamics
simulation (DFT-MD) and isolate the effects of charge and cavitation, comparing
to the Born (linear response) model. We show that using uncorrected Ewald
summation leads to unphysical values for the single ion solvation free energy
and that charging free energies for cations are approximately linear as a
function of charge but that there is a small non-linearity for small anions.
The charge hydration asymmetry (CHA) for hard spheres, determined with quantum
mechanics, is much larger than for the analogous real ions. This suggests that
real ions, particularly anions, are significantly more complex than simple
charged hard spheres, a commonly employed representation.Comment: 28 pages, 5 figure
Real single ion solvation free energies with quantum mechanical simulation
Single ion solvation free energies are one of the most important properties
of electrolyte solutions and yet there is ongoing debate about what these
values are. Only the values for neutral ion pairs are known. Here, we use DFT
interaction potentials with molecular dynamics simulation (DFT-MD) combined
with a modified version of the quasi-chemical theory (QCT) to calculate these
energies for the lithium and fluoride ions. A method to correct for the error
in the DFT functional is developed and very good agreement with the
experimental value for the lithium fluoride pair is obtained. Moreover, this
method partitions the energies into physically intuitive terms such as surface
potential, cavity and charging energies which are amenable to descriptions with
reduced models. Our research suggests that lithium's solvation free energy is
dominated by the free energetics of a charged hard sphere, whereas fluoride
exhibits significant quantum mechanical behavior that cannot be simply
described with a reduced model.Comment: 13 pages, 4 figure
Mass Density Fluctuations in Quantum and Classical descriptions of Liquid Water
First principles molecular dynamics simulation protocol is established using
revised functional of Perdew-Burke-Ernzerhof (revPBE) in conjunction with
Grimme's third generation of dispersion (D3) correction to describe properties
of water at ambient conditions. This study also demonstrates the consistency of
the structure of water across both isobaric (NpT) and isothermal (NVT)
ensembles. Going beyond the standard structural benchmarks for liquid water, we
compute properties that are connected to both local structure and mass density
uctuations that are related to concepts of solvation and hydrophobicity. We
directly compare our revPBE results to the Becke-Lee-Yang-Parr (BLYP) plus
Grimme dispersion corrections (D2) and both the empirical fixed charged model
(SPC/E) and many body interaction potential model (MB-pol) to further our
understanding of how the computed properties herein depend on the form of the
interaction potential
Naturalness, Supersymmetry and Implications for LHC and Dark Matter
It is shown that the Hyperbolic Branch of the radiative electroweak symmetry
breaking contains in it three regions: the Focal Point, Focal Curves, and Focal
Surfaces. Further, the Focal Point is shown to lie on the boundary of a Focal
Curve. These focal regions allow for a small while scalar masses can
become large and may lie in the several TeV region. It is shown that for the
mSUGRA model the current LHC-7 constraint depletes the Focal Point region while
regions on Focal Curves and Focal Surfaces remain largely intact. The LHC
implications for models which lie on Focal Curves are briefly discussed as well
as the implications of dark matter constraints for the Focal Point, Focal
Curves and Focal Surfaces are discussed.Comment: 10 pages, 8 figure
How Do We Combat Bogus Medicines in the Age of the COVID-19 Pandemic?
The COVID-19 pandemic has brought concurrent challenges. The increased incidence of fake and falsified product distribution is one of these problems with tremendous impact, especially in low- and middle-income countries. Up to a tenth of medicines including antibiotics and antimalarial drugs in the African market are considered falsified. Pandemics make this worse by creating an ecosystem of confusion, distraction, and vulnerability stemming from the pandemic as health systems become more stressed and the workload of individuals increased. These environments create opportunities for substandard and falsified medicines to be more easily introduced into the marketplace by unscrupulous operators. In this work, we discussed some of the challenges with fake or falsified product distribution in the context of COVID-19 and proposed strategies to best manage this problem
Interpreting the First CMS and ATLAS SUSY Results
The CMS and the ATLAS Collaborations have recently reported on the search for
supersymmetry with 35 pb of data and have put independent limits on the
parameter space of the supergravity unified model with universal boundary
conditions at the GUT scale for soft breaking, i.e., the mSUGRA model. We
extend this study by examining other regions of the mSUGRA parameter space in
and . Further, we contrast the reach of CMS and ATLAS with 35
pb of data with the indirect constraints, i.e., the constraints from the
Higgs boson mass limits, from flavor physics and from the dark matter limits
from WMAP. Specifically it is found that a significant part of the parameter
space excluded by CMS and ATLAS is essentially already excluded by the indirect
constraints and the fertile region of parameter space has yet to be explored.
We also emphasize that gluino masses as low as 400 GeV but for squark masses
much larger than the gluino mass remain unconstrained and further that much of
the hyperbolic branch of radiative electroweak symmetry breaking, with low
values of the Higgs mixing parameter , is essentially untouched by the
recent LHC analysis.Comment: 3 figure panels, 10 plot
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