1,985 research outputs found
Synthesis, radiolabelling and preclinical evaluation of novel NMDA ligands as potential tracers for positron emission tomography
Association between anaesthetic technique and unplanned admission to intensive care after thoracic lung resection surgery: the second Association of Cardiothoracic Anaesthesia and Critical Care (ACTACC) National Audit
Unplanned intensive care admission is a devastating complication of lung resection and is associated with significantly increased mortality. We carried out a twoâyear retrospective national multicentre cohort study to investigate the influence of anaesthetic and analgesic technique on the need for unplanned postoperative intensive care admission. All patients undergoing lung resection surgery in 16 thoracic surgical centres in the UK in the calendar years 2013 and 2014 were included. We defined critical care admission as the unplanned need for either tracheal intubation and mechanical ventilation or renal replacement therapy, and sought an association between mode of anaesthesia (total intravenous anaesthesia vs. volatile) and analgesic technique (epidural vs. paravertebral) and need for intensive care admission. A total of 253 out of 11,208 patients undergoing lung resection in the study period had an unplanned admission to intensive care in the postoperative period, giving an incidence of intensive care unit admission of 2.3% (95%CI 2.0â2.6%). Patients who had an unplanned admission to intensive care unit had a higher mortality (29.00% vs. 0.03%, p < 0.001), and hospital length of stay was increased (26 vs. 6 days, p < 0.001). Across univariate, complete case and multiple imputation (multivariate) models, there was a strong and significant effect of both anaesthetic and analgesic technique on the need for intensive care admission. Patients receiving total intravenous anaesthesia (OR 0.50 (95%CI 0.34â0.70)), and patients receiving epidural analgesia (OR 0.56 (95%CI 0.41â0.78)) were less likely to have an unplanned admission to intensive care after thoracic surgery. This large retrospective study suggests a significant effect of both anaesthetic and analgesic technique on outcome in patients undergoing lung resection. We must emphasise that the observed association does not directly imply causation, and suggest that wellâconducted, largeâscale randomised controlled trials are required to address these fundamental questions
Finite Temperature Many-Body Theory with the Lipkin Model
We have compared exact numerical results for the Lipkin model at finite
temperature with Hartree-Fock theory and with the results of including in
addition the ring diagrams. In the simplest version of the Lipkin model the
Hartree-Fock approach shows a ``phase transition" which is absent in the exact
results. For more realistic cases, Hartree-Fock provides a very good
approximation and a modest improvement is obtained by adding the ring diagrams.Comment: 17 pages, NUC-MINN-93/16-T (4 figures obtainable by fax from the
authors
Bulk Scale Factor at Very Early Universe
In this paper we propose a higher dimensional Cosmology based on FRW model
and brane-world scenario. We consider the warp factor in the brane-world
scenario as a scale factor in 5-dimensional generalized FRW metric, which is
called as bulk scale factor, and obtain the evolution of it with space-like and
time-like extra dimensions. It is then showed that, additional space-like
dimensions can produce exponentially bulk scale factor under repulsive strong
gravitational force in the empty universe at a very early stage.Comment: 7 pages, October 201
Conductivity sum rule, implication for in-plane dynamics and c-axis response
Recently observed -axis optical sum rule violations indicate non-Fermi
liquid in-plane behavior. For coherent -axis coupling, the observed flat,
nearly frequency independent -axis conductivity implies
a large in-plane scattering rate around and therefore any
pseudogap that might form at low frequency in the normal state will be smeared.
On the other hand incoherent -axis coupling places no restriction on the
value of and gives a more consistent picture of the observed sum rule
violation which, we find in some cases, can be less than half.Comment: 3 figures. To appear in PR
A Debiasing Variational Autoencoder for Deforestation Mapping
Deep Learning (DL) algorithms provide numerous benefits in different applications, and they usually yield successful results in scenarios with enough labeled training data and similar class proportions. However, the labeling procedure is a cost and time-consuming task. Furthermore, numerous real-world classification problems present a high level of class imbalance, as the number of samples from the classes of interest differ significantly. In various cases, such conditions tend to promote the creation of biased systems, which negatively impact their performance. Designing unbiased systems has been an active research topic, and recently some DL-based techniques have demonstrated encouraging results in that regard. In this work, we introduce an extension of the Debiasing Variational Autoencoder (DB-VAE) for semantic segmentation. The approach is based on an end-to-end DL scheme and employs the learned latent variables to adjust the individual sampling probabilities of data points during the training process. For that purpose, we adapted the original DB-VAE architecture for dense labeling in the context of deforestation mapping. Experiments were carried out on a region of the Brazilian Amazon, using Sentinel-2 data and the deforestation map from the PRODES project. The reported results show that the proposed DB-VAE approach is able to learn and identify under-represented samples, and select them more frequently in the training batches, consequently delivering superior classification metrics
Molecular dynamics simulation of the order-disorder phase transition in solid NaNO
We present molecular dynamics simulations of solid NaNO using pair
potentials with the rigid-ion model. The crystal potential surface is
calculated by using an \emph{a priori} method which integrates the \emph{ab
initio} calculations with the Gordon-Kim electron gas theory. This approach is
carefully examined by using different population analysis methods and comparing
the intermolecular interactions resulting from this approach with those from
the \emph{ab initio} Hartree-Fock calculations. Our numerics shows that the
ferroelectric-paraelectric phase transition in solid NaNO is triggered by
rotation of the nitrite ions around the crystallographical c axis, in agreement
with recent X-ray experiments [Gohda \textit{et al.}, Phys. Rev. B \textbf{63},
14101 (2000)]. The crystal-field effects on the nitrite ion are also addressed.
Remarkable internal charge-transfer effect is found.Comment: RevTeX 4.0, 11 figure
Coronal mass ejections as expanding force-free structures
We mode Solar coronal mass ejections (CMEs) as expanding force-fee magnetic
structures and find the self-similar dynamics of configurations with spatially
constant \alpha, where {\bf J} =\alpha {\bf B}, in spherical and cylindrical
geometries, expanding spheromaks and expanding Lundquist fields
correspondingly. The field structures remain force-free, under the conventional
non-relativistic assumption that the dynamical effects of the inductive
electric fields can be neglected. While keeping the internal magnetic field
structure of the stationary solutions, expansion leads to complicated internal
velocities and rotation, induced by inductive electric field. The structures
depends only on overall radius R(t) and rate of expansion \dot{R}(t) measured
at a given moment, and thus are applicable to arbitrary expansion laws. In case
of cylindrical Lundquist fields, the flux conservation requires that both axial
and radial expansion proceed with equal rates. In accordance with observations,
the model predicts that the maximum magnetic field is reached before the
spacecraft reaches the geometric center of a CME.Comment: 19 pages, 9 Figures, accepted by Solar Physic
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