5,634 research outputs found
Mixed Quantum/Classical Approach for Description of Molecular Collisions in Astrophysical Environments
An efficient and accurate mixed quantum/classical theory approach for computational treatment of inelastic scattering is extended to describe collision of an atom with a general asymmetric-top rotor polyatomic molecule. Quantum mechanics, employed to describe transitions between the internal states of the molecule, and classical mechanics, employed for description of scattering of the atom, are used in a self-consistent manner. Such calculations for rotational excitation of HCOOCH3 in collisions with He produce accurate results at scattering energies above 15 cm–1, although resonances near threshold, below 5 cm–1, cannot be reproduced. Importantly, the method remains computationally affordable at high scattering energies (here up to 1000 cm–1), which enables calculations for larger molecules and at higher collision energies than was possible previously with the standard full-quantum approach. Theoretical prediction of inelastic cross sections for a number of complex organic molecules observed in space becomes feasible using this new computational tool
Cardiovascular and nephrological risk in patients with chronic kidney disease in ambulatory care.
Patients with chronic kidney disease (CKD) have higher than in general population all-cause and cardiovascular mortality. Arterial hypertension (HTN) is a powerful potentially modifiable risk factor that affects the majority of patients with chronic kidney disease and one of the main causes of end stage renal disease worldwide. Existing tools for assessment of risk of CKD progression do not take into account arterial hypertension. The aim – to investigate the association between cardiovascular and nephrological risk factors in patients with CKD in ambulatory practice. The study was carried out in the Center of Nephrology Care in Mechnikov Dnipropetrovsk Regional Hospital, Dnipro, Ukraine. 278 patients (114 males and 164 women, aged 41 [31;61] years) with CKD (stages 1-3) who were followed-up in ambulatory care, but required diagnosis or treatment revision were enrolled to the study. All patients were examined and followed-up according to local and European standards. Females slightly prevailed in our study, gender distribution varied insufficiently in groups by CKD progression risk. Elevation of risk of CKD progression was accompanied by rise of prevalence of diabetes mellitus, left ventricle hypertrophy, proteinuria and HTN. Risk of CKD progression correlated with age, systolic and diastolic blood pressure, erythrocyte sedimentation rate, total cholesterol, glomerular filtration rate, albumin excretion rate, duration of HTN and body mass index. Rise of cardiovascular risk was accompanied by rise of proportion of patients with high risk of CKD progression. Increase in risk of CKD progression is associated with rise of burden of cardiovascular risk factors. HTN and blood pressure values should be accounted for assessment of risk of CKD progression
Clinical pattern of systemic sclerosis in Central Ukraine. Association between clinical manifestations of systemic sclerosis and hypertension
Objectives: Systemic sclerosis (SSc) is a rare disease of connective tissue, manifestations of which may vary in different geographical areas. We aimed to describe the clinical portrait of patients with SSc in Dnipropetrovsk region and to investigate how initial clinical and laboratory characteristics are connected with the presence of hypertension in SSc onset.
Material and methods: Patients were enrolled to this study from the registry of SSc patients, established in the Rheumatology Department, Mechnikov Dnipropetrovsk Regional Clinic, Dnipro. Thisregistry contains histories of new cases of SSc from 1993 to 2014. Patients are followed-up and receive treatment according to EULAR and local standards. Diagnosis of SSc was based on ACR and EULAR Criteria for systemic Sclerosis. Two patients developed scleroderma renal crisis during follow-up. This report is a cross-sectional study. We analysed only data of the first visit to a rheumatologist.
Results: In total 148 patients (median age [IQR] – 47 [40; 52] years) fulfilled the inclusion criteria. Male/female ratio was 1 : 20.1. The most frequent clinical signs were Raynaud’s phenomenon and arthritis. The prevalence of skin lesion in dcSSc patients was twice as high as in lcSSc patients. Pulmonary fibrosis occurred significantly more commonly in dcSSc patients. Hypertension occurred in 26–33% in both groups. Patients with hypertension at the SSc onset were seven years older than normotensive patients. More hypertensive patients were classified as lcSSc. Mean GFR was dramatically lower in hypertensive patients.
Conclusions: The most common clinical form in our study was diffuse cutaneous subset of SSc. Hypertension in patients with SSc may be associated with local cutaneous subset of SSc and renal impairment. The strongest predictors of clinical form of SSc are signs of fibrosis (skin lesion and pulmonary fibrosis) and inflammation (arthritis and elevated CRP)
Magnetic reconnection during collisionless, stressed, X-point collapse using Particle-in-Cell simulation
Two cases of weakly and strongly stressed X-point collapse were considered.
Here descriptors weakly and strongly refer to 20 % and 124 % unidirectional
spatial compression of the X-point, respectively. In the weakly stressed case,
the reconnection rate, defined as the out-of-plane electric field in the
X-point (the magnetic null) normalised by the product of external magnetic
field and Alfv\'en speeds, peaks at 0.11, with its average over 1.25 Alfv\'en
times being 0.04. Electron energy distribution in the current sheet, at the
high energy end of the spectrum, shows a power law distribution with the index
varying in time, attaining a maximal value of -4.1 at the final simulation time
step (1.25 Alfv\'en times). In the strongly stressed case, magnetic
reconnection peak occurs 3.4 times faster and is more efficient. The peak
reconnection rate now attains value 2.5, with the average reconnection rate
over 1.25 Alfv\'en times being 0.5. The power law energy spectrum for the
electrons in the current sheet attains now a steeper index of -5.5, a value
close to the ones observed in the vicinity of X-type region in the Earth's
magneto-tail. Within about one Alfv\'en time, 2% and 20% of the initial
magnteic energy is converted into heat and accelerated particle energy in the
case of weak and strong stress, respectively. In the both cases, during the
peak of the reconnection, the quadruple out-of-plane magnetic field is
generated, hinting possibly to the Hall regime of the reconnection. These
results strongly suggest the importance of the collionless, stressed X-point
collapse as a possible contributing factor to the solution of the solar coronal
heating problem or more generally, as an efficient mechanism of converting
magnetic energy into heat and super-thermal particle energy.Comment: Final Accepted Version (Physics of Plasmas in Press 2007
Indirect lattice evidence for the Refined Gribov-Zwanziger formalism and the gluon condensate in the Landau gauge
We consider the gluon propagator at various lattice sizes and
spacings in the case of pure SU(3) Yang-Mills gauge theories using the Landau
gauge fixing. We discuss a class of fits in the infrared region in order to
(in)validate the tree level analytical prediction in terms of the (Refined)
Gribov-Zwanziger framework. It turns out that an important role is played by
the presence of the widely studied dimension two gluon condensate
. Including this effect allows to obtain an acceptable fit up to
1 \'{a} 1.5 GeV, while corroborating the Refined Gribov-Zwanziger prediction
for the gluon propagator. We also discuss the infinite volume extrapolation,
leading to the estimate . As a byproduct, we can
also provide the prediction obtained at
the renormalization scale .Comment: 17 pages, 10 figures, updated version, accepted for publication in
Phs.Rev.
A new signature for color octet pseudoscalars at the LHC
Color octet (pseudo)scalars, if they exist, will be copiously produced at the
CERN Large Hadron Collider (LHC). However, their detection can become a very
challenging task. In particular, if their decay into a pair of top quarks is
kinematically forbidden, the main decay channel would be into two jets, with a
very large background. In this Brief Report we explore the possibility of using
anomaly-induced decays of the color octet pseudoscalars into gauge bosons to
find them at the LHC.Comment: 4 pages, 2 figures. New references adde
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