Accuracy of one-dimensional collision integral in the rigid spheres approximation

The accuracy of calculation of spectral line shapes in one-dimensional approximation is studied analytically in several limiting cases for arbitrary collision kernel and numerically in the rigid spheres model. It is shown that the deviation of the line profile is maximal in the center of the line in case of large perturber mass and intermediate values of collision frequency. For moderate masses of buffer molecules the error of one-dimensional approximation is found not to exceed 5%.Comment: LaTeX, 24 pages, 8 figure

Determining The Efficiency Of Online Learning Models

The study proposes a method for objectively determining the efficiency of online learning based on quantitative data generated by users while studying at online courses. Classifications of online learning models are researched and the efficiency of 4 common models in Ukraine is evaluated

Search for long lived heaviest nuclei beyond the valley of stability

The existence of long lived superheavy nuclei (SHN) is controlled mainly by spontaneous fission and $\alpha$-decay processes. According to microscopic nuclear theory, spherical shell effects at Z=114, 120, 126 and N=184 provide the extra stability to such SHN to have long enough lifetime to be observed. To investigate whether the so-called "stability island" could really exist around the above Z, N values, the $\alpha$-decay half lives along with the spontaneous fission and $\beta$-decay half lives of such nuclei are studied. The $\alpha$-decay half lives of SHN with Z=102-120 are calculated in a quantum tunneling model with DDM3Y effective nuclear interaction using $Q_\alpha$ values from three different mass formulae prescribed by Koura, Uno, Tachibana, Yamada (KUTY), Myers, Swiatecki (MS) and Muntian, Hofmann, Patyk, Sobiczewski (MMM). Calculation of spontaneous fission (SF) half lives for the same SHN are carried out using a phenomenological formula and compared with SF half lives predicted by Smolanczuk {\it et al}. Possible source of discrepancy between the calculated $\alpha$-decay half lives of some nuclei and the experimental data of GSI, JINR-FLNR, RIKEN are discussed. In the region of Z=106-108 with N$\sim$ 160-164, the $\beta$-stable SHN $^{268}_{106}Sg_{162}$ is predicted to have highest $\alpha$-decay half life ($T_\alpha \sim 3.2hrs$) using $Q_\alpha$ value from MMM. Interestingly, it is much greater than the recently measured $T_\alpha$ ($\sim 22s$) of deformed doubly magic $^{270}_{108}Hs_{162}$ nucleus. A few fission-survived long-lived SHN which are either $\beta$-stable or having large $\beta$-decay half lives are predicted to exist near $^{294}110_{184}$, $^{293}110_{183}$, $^{296}112_{184}$ and $^{298}114_{184}$. These nuclei might decay predominantly through $\alpha$-particle emission.Comment: 14 pages, 6 figures, 1 tabl

Alpha-decay lifetimes semiempirical relationship including shell effects

A new version of the semiempirical formula based on fission approach of alpha decay is derived, by using the optimum values of the fitting parameters determined for even-even nuclei, combined with hindrance factors for even-odd, odd-even, and odd-odd nuclides. The deviations from experimental data for two regions of nuclear chart (493 alpha emitters with Z=52-118 and 142 transuranium nuclei including superheavies (Z=92-118), respectively) are compared with those obtained by using the universal curve and the Viola-Seaborg semiempirical relationship.Comment: 11 pages, 3 figures, revtex

A Note on the Cosmic Evolution of the Axion in a Strong Magnetic Field

It has been pointed out in the literature that in the presence of an external magnetic field the axion mass receives an electromagnetic contribution. We show that if a magnetic field with energy density larger than ~10^{-8} times the energy density of the Universe existed at temperatures of a few GeV, that contribution would be dominant and consequently the cosmic evolution of the axion field would change substantially. In particular, the expected axion relic abundance would be lowered, allowing a small relaxation of the present cosmological bound on the Peccei-Quinn constant.Comment: 2 pages, no figures. Minor changes. References added. Accepted for publication in JCA

N=2 Superconformal boundary states for free bosons and fermions

The most general N=2 superconformal boundary states for the c=3 theory consisting of two (uncompactified) free bosons and fermions are constructed. It is shown that the only N=2 boundary states are the familiar Dirichlet boundary states, as well as the Neumann boundary states with an arbitrary electric field.Comment: 20 pages, latex, references added, discussion of GSO projection clarifie

A novel structure-aware sparse learning algorithm for brain imaging genetics

Brain imaging genetics is an emergent research field where the association between genetic variations such as single nucleotide polymorphisms (SNPs) and neuroimaging quantitative traits (QTs) is evaluated. Sparse canonical correlation analysis (SCCA) is a bi-multivariate analysis method that has the potential to reveal complex multi-SNP-multi-QT associations. Most existing SCCA algorithms are designed using the soft threshold strategy, which assumes that the features in the data are independent from each other. This independence assumption usually does not hold in imaging genetic data, and thus inevitably limits the capability of yielding optimal solutions. We propose a novel structure-aware SCCA (denoted as S2CCA) algorithm to not only eliminate the independence assumption for the input data, but also incorporate group-like structure in the model. Empirical comparison with a widely used SCCA implementation, on both simulated and real imaging genetic data, demonstrated that S2CCA could yield improved prediction performance and biologically meaningful findings

B-blockers, calcium antagonists, and mortality in stable coronary artery disease: An international cohort study

Aims: The effect of first-line antianginal agents, β-blockers, and calcium antagonists on clinical outcomes in stable coronary artery disease (CAD) remains uncertain. Methods and results We analysed the use of β-blockers or calcium antagonists (baseline and annually) and outcomes in 22 006 stable CAD patients (enrolled 2009–2010) followed annually to 5 years, in the CLARIFY registry (45 countries). Primary outcome was all-cause death. Secondary outcomes were cardiovascular death and the composite of cardiovascular death/non-fatal myocardial infarction (MI). After multivariable adjustment, baseline β-blocker use was not associated with lower all-cause death [1345 (7.8%) in users vs. 407 (8.4%) in non-users; hazard ratio (HR) 0.94, 95% confidence interval (CI) 0.84–1.06; P = 0.30]; cardiovascular death [861 (5.0%) vs. 262 (5.4%); HR 0.91, 95% CI 0.79–1.05; P = 0.20]; or cardiovascular death/non-fatal MI [1272 (7.4%) vs. 340 (7.0%); HR 1.03, 95% CI 0.91–1.16; P = 0.66]. Sensitivity analyses according to β-blocker use over time and to prescribed dose produced similar results. Among prior MI patients, for those enrolled in the year following MI, baseline β-blocker use was associated with lower all-cause death [205 (7.0%) vs. 59 (10.3%); HR 0.68, 95% CI 0.50–0.91; P = 0.01]; cardiovascular death [132 (4.5%) vs. 49 (8.5%); HR 0.52, 95% CI 0.37–0.73; P = 0.0001]; and cardiovascular death/non-fatal MI [212 (7.2%) vs. 59 (10.3%); HR 0.69, 95% CI 0.52–0.93; P = 0.01]. Calcium antagonists were not associated with any difference in mortality. Conclusion In this contemporary cohort of stable CAD, β-blocker use was associated with lower 5-year mortality only in patients enrolled in the year following MI. Use of calcium antagonists was not associated with superior mortality, regardless of history of MI

Classification of real three-dimensional Lie bialgebras and their Poisson-Lie groups

Classical r-matrices of the three-dimensional real Lie bialgebras are obtained. In this way all three-dimensional real coboundary Lie bialgebras and their types (triangular, quasitriangular or factorizable) are classified. Then, by using the Sklyanin bracket, the Poisson structures on the related Poisson-Lie groups are obtained.Comment: 17 page

К проблеме радиационного канцерогенеза после лечения лимфомы ходжкина и острого лимфобластного лейкоза у детей и подростков

Twenty-six cases with secondary malignant tumors in children and adolescents receiving treatment for Hodgkin’s lymphoma and acute lymphoblastic leukemia were analyzed. In all cases the lesion had developed in an area of previous radiation treatment. The interval between the primary treatment and secondary cancer development was from 3 to 29 years. The radiation therapy dose was from 12 to 45 Gy. Treatment of secondary cancer was successful only in 5 patients, the remaining patients died of disease progression. The risk of developing secondary cancer should be considered when planning treatment for patients with hemoblastosis. In cases with favorable prognosis (complete remission after induction chemotherapy and other signs of favorable prognosis) it is advisable to withhold radiation therapy as the most important risk factor for cancer.Проведен анализ 26 случаев вторых злокачественных опухолей у детей и подростков, получавших комплексное лечение по по- воду лимфомы Ходжкина и острого лимфобластного лейкоза. Во всех случаях опухоли развились в зоне бывшего радиационного воздействия или по краю ее. Интервал между первичным лечением и развитием второй опухоли составил от 3 до 29 лет, дозы лучевой терапии – от 12 до 45 Гр. Только у 5 больных лечение второй опухоли было успешным, остальные умерли от ее прогрес- сирования. Риск развития второй опухоли должен учитываться при планировании комплексного лечения больных гемобластозами и в случаях благоприятного прогноза (достижение полной ремиссии в результате индукционной химиотерапии, наличие других признаков благоприятного прогноза) целесообразно воздерживаться от проведения лучевой терапии как наиболее канцерогенного фактора в лечебном комплексе