103,772 research outputs found
Conversion of a gastric band into an intraperitoneal port in a patient with optimally debulked stage 3C serous ovarian carcinoma
Intraperitoneal (IP) chemotherapy in women with optimally debulked stage 3 ovarian cancer improves overall survival and progression-free survival, and its use has been encouraged in the adjuvant treatment of appropriately selected patients (Armstrong et al., 2006; Jaaback and Johnson, 2006). We describe a case in which a previously inserted adjustable gastric band was converted to an IP chemotherapy port during a laparotomy for advanced ovarian cancer
The impact of an emotionally expressive writing intervention on eating pathology in female students
© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Introduction: Previous research demonstrating emotional influences on eating and weight suggest that emotionally expressive writing may have a significant impact on reducing risk of eating pathology. This study examined the effects of writing about Intensely Positive Experiences on weight and disordered eating during a naturalistic stressor. Method: Seventy-one female students completed an expressive or a control writing task before a period of exams. Both groups were compared on BMI (kg/m2) and the Eating Disorder Examination – Questionnaire (EDE-Q) before the writing task and at 8-week follow-up. A number of secondary analyses were also examined (to identify potential mediators) including measures of attachment, social rank, self-criticism and self-reassurance, stress and mood. Results: There was a significant effect of intervention on changes in the subscales of the EDE-Q (p = .03). Specifically, expressive writers significantly reduced their dietary restraint while those in the control group did not. There was no significant effect of the intervention on changes in BMI or the other subscales of the EDE-Q (Eating, Weight and Shape Concern). There was also no effect of writing on any of the potential mediators in the secondary analyses. Discussion: Emotionally expressive writing may reduce the risk of dietary restraint in women but these findings should be accepted with caution. It is a simple and light touch intervention that has the potential to be widely applied. However, it remains for future research to replicate these results and to identify the mechanisms of action.Peer reviewedFinal Published versio
Decoherence of adiabatically steered quantum systems
We study the effect of Markovian environmental noise on the dynamics of a
two-level quantum system which is steered adiabatically by an external driving
field. We express the master equation taking consistently into account all the
contributions to the lowest non-vanishing order in the coupling to the
Markovian environment. We study the master equation numerically and
analytically and we find that, in the adiabatic limit, a zero-temperature
environment does not affect the ground state evolution. As a physical
application, we discuss extensively how the environment affects Cooper pair
pumping. The adiabatic ground state pumping appears to be robust against
environmental noise. In fact, the relaxation due to the environment is required
to avoid the accumulation of small errors from each pumping cycle. We show that
neglecting the non-secular terms in the master equation leads to unphysical
results, such as charge non-conservation. We discuss also a possible way to
control the environmental noise in a realistic physical setup and its influence
on the pumping process.Comment: 13 pages, 11 figures. Final versio
Diffractive energy spreading and its semiclassical limit
We consider driven systems where the driving induces jumps in energy space:
(1) particles pulsed by a step potential; (2) particles in a box with a moving
wall; (3) particles in a ring driven by an electro-motive-force. In all these
cases the route towards quantum-classical correspondence is highly non-trivial.
Some insight is gained by observing that the dynamics in energy space, where
is the level index, is essentially the same as that of Bloch electrons in a
tight binding model, where is the site index. The mean level spacing is
like a constant electric field and the driving induces long range hopping
1/(n-m).Comment: 19 pages, 11 figs, published version with some improved figure
Localization and delocalization errors in density functional theory and implications for band-gap prediction
The band-gap problem and other systematic failures of approximate functionals
are explained from an analysis of total energy for fractional charges. The
deviation from the correct intrinsic linear behavior in finite systems leads to
delocalization and localization errors in large or bulk systems. Functionals
whose energy is convex for fractional charges such as LDA display an incorrect
apparent linearity in the bulk limit, due to the delocalization error. Concave
functionals also have an incorrect apparent linearity in the bulk calculation,
due to the localization error and imposed symmetry. This resolves an important
paradox and opens the possibility to obtain accurate band-gaps from DFT.Comment: 4 pages 4 figure
The thermal influence of continents on a model-generated January climate
Two climate simulations were compared. Both climate computations were initialized with the same horizontally uniform state of rest. However, one is carried out on a water planet (without continents), while the second is repeated on a planet with geographically realistic but flat (sea level) continents. The continents in this experiment have a uniform albedo of 0.14, except where snow accumulates, a uniform roughness height of 0.3 m, and zero water storage capacity. Both runs were carried out for a 'perpetual January' with solar declination fixed at January 15
Summary of results of January climate simulations with the GISS coarse-mesh model
The large scale climates generated by extended runs of the model are relatively independent of the initial atmospheric conditions, if the first few months of each simulation are discarded. The perpetual January simulations with a specified SST field produced excessive snow accumulation over the continents of the Northern Hemisphere. Mass exchanges between the cold (warm) continents and the warm (cold) adjacent oceans produced significant surface pressure changes over the oceans as well as over the land. The effect of terrain and terrain elevation on the amount of precipitation was examined. The evaporation of continental moisture was calculated to cause large increases in precipitation over the continents
The discontinuous nature of the exchange-correlation functional -- critical for strongly correlated systems
Standard approximations for the exchange-correlation functional have been
found to give big errors for the linearity condition of fractional charges,
leading to delocalization error, and the constancy condition of fractional
spins, leading to static correlation error. These two conditions are now
unified for states with both fractional charge and fractional spin: the exact
energy functional is a plane, linear along the fractional charge coordinate and
constant along the fractional spin coordinate with a line of discontinuity at
the integer. This sheds light on the nature of the derivative discontinuity and
calls for explicitly discontinuous functionals of the density or orbitals that
go beyond currently used smooth approximations. This is key for the application
of DFT to strongly correlated systems.Comment: 5 pages 2 figure
Charge Transfer in Partition Theory
The recently proposed Partition Theory (PT) [J.Phys.Chem.A 111, 2229 (2007)]
is illustrated on a simple one-dimensional model of a heteronuclear diatomic
molecule. It is shown that a sharp definition for the charge of molecular
fragments emerges from PT, and that the ensuing population analysis can be used
to study how charge redistributes during dissociation and the implications of
that redistribution for the dipole moment. Interpreting small differences
between the isolated parts' ionization potentials as due to environmental
inhomogeneities, we gain insight into how electron localization takes place in
H2+ as the molecule dissociates. Furthermore, by studying the preservation of
the shapes of the parts as different parameters of the model are varied, we
address the issue of transferability of the parts. We find good transferability
within the chemically meaningful parameter regime, raising hopes that PT will
prove useful in chemical applications.Comment: 12 pages, 16 figure
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