1,716 research outputs found

    Anomalous Hall effect in insulating Ga1-xMnxAs

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    We have investigated the effect of doping by Te on the anomalous Hall effect in Ga1-xMnxAs (x = 0.085). For this relatively high value of x the temperature dependence of resistivity shows an insulating behavior. It is well known that in Ga1-xMnxAs the Mn ions naturally act as acceptors. Additional doping by Te donors decreases the Curie temperature and increases the anomalous Hall resistivity. With increasing Te concentration the long-range ferromagnetic order in Ga1-xMnxAs eventually disappears, and paramagnetic-to-spin glass transition is observed instead. The critical concentration of holes required for establishing ferromagnetic order in Ga1-xMnxAs (x = 0.085) has been estimated by using the magnetic polaron percolation theory proposed by Kaminski and Das Sarma [Phys.Rev.Lett. 88, 247202 (2002)].Comment: 15 pages, 5 figures. Phys. Rev. B (to be published

    True Neutrality as a New Type of Flavour

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    A classification of leptonic currents with respect to C-operation requires the separation of elementary particles into the two classes of vector C-even and axial-vector C-odd character. Their nature has been created so that to each type of lepton corresponds a kind of neutrino. Such pairs are united in families of a different C-parity. Unlike the neutrino of a vector type, any C-noninvariant Dirac neutrino must have his Majorana neutrino. They constitute the purely neutrino families. We discuss the nature of a corresponding mechanism responsible for the availability in all types of axial-vector particles of a kind of flavour which distinguishes each of them from others by a true charge characterized by a quantum number conserved at the interactions between the C-odd fermion and the field of emission of the corresponding types of gauge bosons. This regularity expresses the unidenticality of truly neutral neutrino and antineutrino, confirming that an internal symmetry of a C-noninvariant particle is described by an axial-vector space. Thereby, a true flavour together with the earlier known lepton flavour predicts the existence of leptonic strings and their birth in single and double beta decays as a unity of flavour and gauge symmetry laws. Such a unified principle explains the availability of a flavour symmetrical mode of neutrino oscillations.Comment: 19 pages, LaTex, Published version in IJT

    Physical inactivity in nine European and Central Asian countries: an analysis of national population-based survey results

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    Background Physical inactivity is a major risk factor for non-communicable diseases. However, recent and systematically obtained national-level data to guide policy responses are often lacking, especially in countries in Eastern Europe and Central Asia. This article describes physical inactivity patterns among adults in Armenia, Azerbaijan, Belarus, Georgia, Kyrgyzstan, Republic of Moldova, Tajikistan, Turkey and Uzbekistan. Methods Data were collected using the Global Physical Activity Questionnaire drawing nationally representative samples of adults in each country. The national prevalence of physical inactivity was calculated as well as the proportional contribution to total physical activity (PA) during work, transport and leisure-time. An adjusted logistic regression model was applied to analyze the association of age, gender, education, household status and income with physical inactivity. Results National prevalence of physical inactivity ranged from 10.1% to 43.6%. The highest proportion of PA was registered during work or in the household in most countries, whereas the lowest was during leisure-time in all countries. Physical inactivity was more likely with older age in eight countries, with female gender in three countries, and with living alone in three countries. There was no clear pattern of association with education and income. Conclusion Prevalence of physical inactivity is heterogeneous across the region. PA during leisure-time contributes minimally to total PA in all countries. Policies and programs that increase opportunities for active travel and leisure-time PA, especially for older adults, women and people living alone will be an essential part of strategies to increase overall population PA.The authors gratefully acknowledge support from a grant from the Government of the Russian Federation in the context of the WHO European Office for the Prevention and Control of NCDs

    Reeconstructing Sigma0 decays in STAR

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    Typical comparisons of data from nuclear collisions to particle production models require a caveat for (anti)Lambda yields from experimental inability to separate the contributions of those yields from Sigma state decays. Recent analysis in STAR is leading toward resolving the contribution from excited Sigma states, but the bulk contribution comes from electromagnetic decays of the (anti)Sigma0. In the STAR detector, photon conversions into e+e- pairs in the detector material have been used to identify photons from pi0 decays. A similar technique has been used here to identify photons from (anti)Sigma0 decays in conjunction with STAR's excellent PID capabilities for finding the associated (anti)Lambda daughters. We report here on progress toward measuring the (anti)Sigma0 yields in various nuclear collisions at RHIC.Comment: 8 pages, 5 figures, proceedings of Hot Quarks 2004 workshop, submitted to J. Phys.

    The Study of the Internal Structure of Archaeological Coins from the Fortress of Uzundara Using Neutron Radiography and Tomography

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    The study of the internal structure of archaeological objects is one of the most important tasks of archeology. Obtaining images of the internal structure of objects allows the installation of neutron tomography. Ancient coins found in the fortress of Uzundara were chosen as objects of study.Исследование проводилось в рамках программы научно-исследовательских работ Института ядерной физики Академии наук Республики Узбекистана на 2020-2024 годы, по теме «Радиационно - стимулированные процессы при ядерной трансмутации легированного монокристаллического кремния» в лаборатории радиационной физики и техники твердотельной электроники

    Left Ventricular Function after Revascularization in Patients with Chronical Coronary Syndromes

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    Background: The purpose of this study was to determine the dynamics of morpho-functional and myocardial deformation characteristics of the left ventricle after revascularization in patients with chronic coronary syndromes (CCS). Methods and Results: The study included 136 CCS patients of both sexes with stable anginal symptoms [(i) clinical scenario] and asymptomatic coronary artery disease (CAD) at screening [(vi) clinical scenario]. Diagnosis of CCS was performed according to the 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. All patients underwent the following examinations: assessment of traditional risk factors, physical examination, general clinical and laboratory blood tests, 12-lead ECG, transthoracic echocardiography, two-dimensional speckle tracking echocardiography (STE), and coronary angiography (CAG). The SYNTAX score was calculated retrospectively according to the SYNTAX score algorithm. A total of 100 patients with CCS were enrolled in the main group (MG) and underwent revascularization by PCI with intracoronary stenting using drug-eluting stents. Among the main-group patients, one-vessel, two-vessel, and three-vessel CAD were detected in 36(26.5%), 34(25%), and 30(22.0%) cases, respectively. The comparison group (CG) included 36 CCS patients with hemodynamically non-significant coronary lesions (<50% stenosis). LVEF values were within the normal range in all groups, with the highest value in the CG, followed by the one-, two- and three-vessel lesion groups. LVEF obtained by the area-length method and modified biplane Simpson's method did not differ. The assessment of the contractile function of the LV myocardium was also obtained by assessing the global longitudinal strain (GLS) and global longitudinal strain rate (GLSR). The comparative analysis of the LV myocardial deformation properties in the studied groups showed that less negative GLS and GLSR were found in the three-vessel CAD, followed by the two-vessel and one-vessel CAD groups, and CG. CG demonstrated more negative GLS and GLSR than all MG subgroups. We analyzed the effect of revascularization on the GLS and found no statistically significant differences before and 48 hours after revascularization in all studied MG subgroups and CG. Thirty days after revascularization, GLS significantly showed more negative values in all MG subgroups: -18.12±0.63 versus -17.9±0.4 in one-vessel CAD, -16.13±0.71 versus -15.9±0.4 in two-vessel CAD and -13.91±1.25 versus -13.1±1.1 in three-vessel CAD. In CG with medical treatment only, GLS did not change statistically significantly but had more negative values than in the studied MG subgroups. Analysis of changes in LVEF after revascularization in the MG of patients with one-, two- and three-vessel CAD and in the CG after medical treatment did not reveal statistically significant dynamics. Conclusion: the results indicate the absence of statistically significant changes in myocardial deformation indicators and morpho-functional parameters of the left ventricle in CCS patients 48 hours after revascularization. Thirty days after revascularization, GLS significantly improves, while LVEF remains unchanged. GLS is superior to LVEF in visualizing improvement in LV function after revascularization in patients with CCS
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