3,932 research outputs found
Review of the measurements of the strong coupling constant at LEP 2
Since 1995, LEP has steadily increased the center of mass energy of the
colliding beams, from the M_Z resonance to 133, 161 and 172 GeV. New
measurements of the strong coupling constant, alpha_s, at these energies have
been performed by the LEP experiments, L3, ALEPH, OPAL and DELPHI. In this
article, the new results are summarized, and combined with the previous LEP
measurement of alpha_s(M_Z) in order to obtain an updated LEP average of
alpha_s(M_Z) = 0.120 +- 0.005.Comment: 5-6 pages, 3 figures. Talk given at the DIS 97 conference, Chicago,
April 1997.Replacement: update figure 1. Also available here
http://hep.ph.liv.ac.uk/~martis
Image-guided Surgical Microscope
We present an image-guided surgical microscope system using augmented reality image overlays added onto one of the views of the operating microscope. With this system, segmented objects, outlines of risk regions, access pathways or 3D objects, previously extracted from preoperative tomographic images can be directly displayed as augmented reality overlays on the microscope image
Complete-Graph Tensor Network States: A New Fermionic Wave Function Ansatz for Molecules
We present a new class of tensor network states that are specifically
designed to capture the electron correlation of a molecule of arbitrary
structure. In this ansatz, the electronic wave function is represented by a
Complete-Graph Tensor Network (CGTN) ansatz which implements an efficient
reduction of the number of variational parameters by breaking down the
complexity of the high-dimensional coefficient tensor of a
full-configuration-interaction (FCI) wave function. We demonstrate that CGTN
states approximate ground states of molecules accurately by comparison of the
CGTN and FCI expansion coefficients. The CGTN parametrization is not biased
towards any reference configuration in contrast to many standard quantum
chemical methods. This feature allows one to obtain accurate relative energies
between CGTN states which is central to molecular physics and chemistry. We
discuss the implications for quantum chemistry and focus on the spin-state
problem. Our CGTN approach is applied to the energy splitting of states of
different spin for methylene and the strongly correlated ozone molecule at a
transition state structure. The parameters of the tensor network ansatz are
variationally optimized by means of a parallel-tempering Monte Carlo algorithm
Potential of the three-Terminal heterojunction bipolar transistor solar cell for space applications
Multi-Terminal multi-junction solar cells (MJSC) offer higher efficiency potential than series connected (two-Terminal) ones. In addition, for terrestrial applications, the efficiency of multi-Terminal solar cells is less sensitive to solar spectral variations than the two-Terminal series-connected one. In space, generally, cells are always illuminated with AM0 spectrum and no impact is expected from spectral variations. Still, in space, the multi-Terminal approach offers some advantages in comparison with the series-connected architecture approach derived from a higher end of life (EOL) efficiency. In this work we review the potential of multi-Terminal solar cells for achieving extended EOL efficiencies with emphasis in the potential of the three-Terminal heterojunction bipolar transistor solar cell, a novel multi-Terminal MJSC architecture with a simplified structure not requiring, for example, tunnel junctions
An ALMA Early Science survey of molecular absorption lines toward PKS1830-211 -- Analysis of the absorption profiles
We present the first results of an ALMA spectral survey of strong absorption
lines for common interstellar species in the z=0.89 molecular absorber toward
the lensed blazar PKS1830-211. The dataset brings essential information on the
structure and composition of the absorbing gas in the foreground galaxy. In
particular, we find absorption over large velocity intervals (gtrsim 100 km/s)
toward both lensed images of the blazar. This suggests either that the galaxy
inclination is intermediate and that we sample velocity gradients or streaming
motions in the disk plane, that the molecular gas has a large vertical
distribution or extraplanar components, or that the absorber is not a simple
spiral galaxy but might be a merger system. The number of detected species is
now reaching a total of 42 different species plus 14 different rare
isotopologues toward the SW image, and 14 species toward the NE line-of-sight.
The abundances of CH, H2O, HCO+, HCN, and NH3 relative to H2 are found to be
comparable to those in the Galactic diffuse medium. Of all the lines detected
so far toward PKS1830-211, the ground-state line of ortho-water has the deepest
absorption. We argue that ground-state lines of water have the best potential
for detecting diffuse molecular gas in absorption at high redshift.Comment: Accepted for publication in A&
DisminuciĂłn de la reserva de flujo coronario en pacientes con insuficiencia cardĂaca no isquĂ©mica
Introduction and objectives. Coronary flow reserve
(CFR) is impaired not only in ischemic heart disease, but
also in cardiac diseases that may or may not course with
heart failure. The aim of the present study was to determine
if the severity of heart failure can influence CFR impairment.
Methods. Forty patients with non-ischemic heart disease
and heart failure were studied 41 times. Four groups
were established: 1. 10 patients in functional class III-IV;
2. 10 patients in functional class II not taking beta-blockers;
3. 11 patients in class II treated with carvedilol, and 4.
10 patients in class I. These patients had a history of heart
failure and systolic dysfunction. Myocardial blood flow
(MBF) was measured with positron emission tomography
(PET) and N-13 ammonia at rest (r) and during adenosine
triphosphate (ATP) infusion.
Results. MBF and CFR were significantly higher in
group 4 (1.95 ± 0.58 and 2.40 ± 0.95 ml/min/g) than in
group 1 (1.02 ± 0.52 and 1.46 ± 0.48 ml/min/g). CFR tended
to be higher in groups 2 (1.73 ± 0.72), and 3 (1.89 ±
0.75) vs group 1. No significant correlation was found between
CFR and the following variables: age, systolic blood
pressure, ventricular mass index, ventricular volume indexes,
and ejection fraction.
Conclusions. Coronary microvascular function is impaired
in non-ischemic heart failure, and the impairment is
related to functional class, regardless of the underlying
responsible heart disease
Semicarbazide-sensitive amine oxidase / vascular adhesion protein-1 activity exerts an antidiabetic action in Goto-Kakizaki rats
n this study we have explored whether the bifunctional protein semicarbazide-sensitive amine oxidase (SSAO)/vascular adhesion protein-1 (VAP-1) represents a novel target for type 2 diabetes. To this end, Goto-Kakizaki (GK) diabetic rats were treated with the SSAO substrate benzylamine and with low ineffective doses of vanadate previously shown to have antidiabetic effects in streptozotocin-induced diabetic rats. The administration of benzylamine in combination with vanadate in type 2 diabetic rats acutely stimulated glucose tolerance, and the chronic treatment normalized hyperglycemia, stimulated glucose transport in adipocytes, and reversed muscle insulin resistance. Acute in vivo administration of benzylamine and vanadate stimulated skeletal muscle glucose transport, an effect that was also observed in incubated muscle preparations coincubated with adipose tissue explants or with human recombinant SSAO. Acute administration of benzylamine/vanadate also ameliorated insulin secretion in diabetic GK rats, and this effect was also observed in incubated pancreatic islets. In keeping with these observations, we also demonstrate that pancreatic islets express SSAO/VAP-1. As far as mechanisms of action, we have found that benzylamine/vanadate causes enhanced tyrosine phosphorylation of proteins and reduced protein tyrosine phosphatase activity in adipocytes. In addition, incubation of human recombinant SSAO, benzylamine, and vanadate generates peroxovanadium compounds in vitro. Based on these data, we propose that benzylamine/vanadate administration generates peroxovanadium locally in pancreatic islets, which stimulates insulin secretion and also produces peroxovanadium in adipose tissue, activating glucose metabolism in adipocytes and in neighboring muscle. This opens the possibility of using the SSAO/VAP-1 activity as a local generator of protein tyrosine phosphatase inhibitors in antidiabetic therapy
18F-FDG metabolism in a rat model of chronic infarction: a 17-sector semiquantitative analysis
Strategies to establish the functional benefit of cell therapy in cardiac regeneration and the potential mechanism are needed. Aims: Development of a semi-quantitative method for non invasive assessment of cardiac viability and function in a rat model of myocardial infarction (MI) based on the use of microPET. Animals, methods: Ten rats were subjected to myocardial imaging 2, 7, 14, 30, 60 and 90 days after left coronary artery ligation. Intravenous 18F-fluoro-2-deoxy-2-D-glucose (18F-FDG) was administered and regional 18F activity concentrations per unit area were measured in 17 regions of interest (ROIs) drawn on cardiac polar maps. By comparing the differences in 18F uptake between baseline and each of the follow up time points, parametric polar maps of statistical significance (PPMSS) were calculated. Left ventricular ejection fraction (LVEF) was blindly assessed echocardiographically. All animals were sacrificed for histopathological analysis after 90 days. Results: The diagnostic quality of 18F-FDG microPET images was excellent. PPMSS demonstrated a statistically significant decrease in 18F concentrations as early as 48 hours after MI in 4 of the 17 ROIs (segments 7, 13, 16 and 17; p <0.05) that persisted throughout the study. Semi-quantitative analysis of 18F-FDG uptake correlated with echocardiographic decrease in LVEF (p <0.001). Conclusion: The use of PPMSS based on 18F-FDG-microPET provides valuable semi-quantitative information of heart glucose metabolism allowing for non-invasive follow up thus representing a useful strategy for assessment of novel therapies in cardiac regeneration
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