Ducks on the torus: existence and uniqueness

We show that there exist generic slow-fast systems with only one (time-scaling) parameter on the two-torus, which have canard cycles for arbitrary small values of this parameter. This is in drastic contrast with the planar case, where canards usually occur in two-parametric families. Here we treat systems with a convex slow curve. In this case there is a set of parameter values accumulating to zero for which the system has exactly one attracting and one repelling canard cycle. The basin of the attracting cycle is almost the whole torus.Comment: To appear in Journal of Dynamical and Control Systems, presumably Vol. 16 (2010), No. 2; The final publication is available at www.springerlink.co

Fast Predictions of Lattice Energies by Continuous Isometry Invariants of Crystal Structures

Crystal Structure Prediction (CSP) aims to discover solid crystalline materials by optimizing periodic arrangements of atoms, ions or molecules. CSP takes weeks of supercomputer time because of slow energy minimizations for millions of simulated crystals. The lattice energy is a key physical property, which hints at thermodynamic stability of a crystal but has no simple analytic expression. Past machine learning approaches to predict the lattice energy used slow crystal descriptors depending on manually chosen parameters. The new area of Periodic Geometry offers much faster isometry invariants that are also continuous under perturbations of atoms. Our experiments on simulated crystals confirm that a small distance between the new invariants guarantees a small difference of energies. We compare several kernel methods for invariant-based predictions of energy and achieve the mean absolute error of less than 5 kJ/mole or 0.05 eV/atom on a dataset of 5679 crystals

The Decay of Accreting Triple Systems as Brown Dwarf Formation Scenario

We investigate the dynamical decay of non-hierarchical accreting triple systems and its implications on the ejection model as Brown Dwarf formation scenario. A modified chain-regularization scheme is used to integrate the equations of motion, that also allows for mass changes over time as well as for momentum transfer from the accreted gas mass onto the bodies. We integrate an ensemble of triple systems within a certain volume with different accretion rates, assuming several prescriptions of how momentum is transferred onto the bodies. We follow their evolution until the systems have decayed. We analyze the end states and decay times of these systems and determine the fraction of Brown Dwarfs formed, their escape speeds as well as the semi-major axis distribution of the formed Brown Dwarf binaries. We find that the formation probability of Brown Dwarfs depends strongly on the assumed momentum transfer which is related to the motion of the gas. Due to ongoing accretion and consequent shrinkage of the systems, the median escape velocity is increased by a factor of 2 and the binary separations are decreased by a factor of 5 compared with non-accreting systems. Furthermore, the obtained semi-major axis distribution drops off sharply to either side of the median, which is also supported by observations. We conclude that accretion and momentum transfer of accreted gas during the dynamical decay of triple systems is able to produce the observed distribution of close binary Brown Dwarfs, making the ejection model a viable option as Brown Dwarf formation scenario.Comment: 31 pages, 8 figures, accepted for publication in Ap

Діастолічна функція лівого шлуночка та рівень N-кінцевого промозкового натрійуретичного пептиду у хворих на фібриляцію передсердь

In our study 100 consecutive non-valvular permanent atrial fibrillation patients with NYHA I – III heart failure, 43 - 86 years old (65 men and 35 women) were examined. Control group consisted of 30 patients with arterial hypertension and coronary artery disease matched by age, sex with basic group. Relationship of NT-proBNP with echocardiographic parameters of left heart were studied. Transthoracic echocardiography with tissue doppler measurements were performed on echocardiograph “SONOS7500”. For left ventricular filling pressure assessment ratio Em/Ea was used due to its diagnostic value in atrial fibrillation (regardless of left ventricular ejection fraction). Mean left ventricular filling pressure was increased in patients with heart failure: in atrial fibrillation group and controls as well. In comparison with controls atrial fibrillation group was more likely to have higher both systolic and diastolic left atrial square and volume. According to Em/Ea in 95% of patients with non-valvular atrial fibrillation high left ventricular filling pressure was observed, this testifies to diastolic dysfunction. This parameter correlated well with left atrial square and volume during systole and diastole. Correlation between NT pro-BNP level and NYHA class of  heart failure, left ventricular filling pressure was determined in patients with atrial fibrillation. Tissue doppler echocardiography makes it possible to diagnose left ventricular diastolic dysfunction in atrial fibrillation patients.Обследовано 100 пациентов с постоянной формой фиб­рилляции предсердий неклапанного генеза и хронической недостаточностью І – ІІІ функционального класса в возрасте 43 – 86 лет, из них 65 мужчин и 35 – женщин. Контрольную группу составили 30 пациентов с ИБС и ГБ, сопоставимых по возрасту и полу с основной группой. Изучали уровень N-проМНП и его связь с эхокардиографическими показателями функции левых отделов сердца у данной категории больных. Эхокар­диографическое исследование и тканевая допплерография проводились на аппарате «SONOS 7500». Для оценки давления наполнения левого желудочка рассчитывали соотношение Em/Ea, которое полностью сохраняет свое диагностическое значение (независимо от фракции выброса левого желудочка) при фибрилляции предсердий. Средний показатель давления наполнения левого желудочка был увеличен у больных с хронической сердечной недостаточностью, как при постоянной фибрилляции предсердий, так и на фоне синусового ритма. Было установлено достоверное увеличение размеров левого предсердия, его площадей и объемов в систолу и ди­астолу в группе пациентов с фибрилляцией предсердий в сравнении с группой контроля. По данным показателя Еm/Eaу 95% пациентов с фибрилляцией предсердий неклаппаного генеза выявлено повышение давления наполнения левого желудочка, что свидетельствует о нарушении диастолической функции. Данный пока­затель достоверно коррелировал с объемами и площадями левого предсердия в систолу и диастолу. Уста­новлена достоверная связь между уровнем N-проМНП и функциональным классом сердечной недо­ста­точности, уровнем давления наполнений левого желудочка у пациентов с фибрилляцией предсердий. Использование тканевого допплеровского исследования позволяет диагностировать нарушение диасто­лической функции левого желудочка при фибрилляции предсердий.In our study 100 consecutive non-valvular permanent atrial fibrillation patients with NYHA I – III heart failure, 43 - 86 years old (65 men and 35 women) were examined. Control group consisted of 30 patients with arterial hypertension and coronary artery disease matched by age, sex with basic group. Relationship of NT-proBNP with echocardiographic parameters of left heart were studied. Transthoracic echocardiography with tissue doppler measurements were performed on echocardiograph “SONOS 7500”. For left ventricular filling pressure assessment ratio Em/Ea was used due to its diagnostic value in atrial fibrillation (regardless of left ventricular ejection fraction).Mean left ventricular filling pressure was increased in patients with heart failure: in atrial fibrillation group and controls as well. In comparison with controls atrial fibrillation group was more likely to have higher both systolic and diastolic left atrial square and volume. According to Em/Ea in 95% of patients with non-valvular atrial fibrillation high left ventricular filling pressure was observed, this testifies to diastolic dysfunction. This parameter correlated well with left atrial square and volume during systole and diastole. Correlation between NT pro-BNP level and NYHA class of  heart failure, left ventricular filling pressure was determined in patients with atrial fibrillation. Tissue doppler echocardiography makes it possible to diagnose left ventricular diastolic dysfunction in atrial fibrillation patients

The 0.4-Mo Eclipsing Binary CU Cancri: Absolute Dimensions, Comparison with Evolutionary Models and Possible Evidence for a Circumstellar Dust Disk

Photometric observations in the R and I bands of the detached M-type double-lined eclipsing binary CU Cnc have been acquired and analysed. The photometric elements obtained from the analysis of the light curves have been combined with an existing spectroscopic solution to yield high-precision (errors<2%) absolute dimensions: M_A=0.4333+/-0.0017 Mo, M_B=0.3980+/-0.0014 Mo, R_A=0.4317+/-0.0052 Ro, and R_B=0.3908+/-0.0094 Ro. The mean effective temperature of the system has been estimated to be Teff=3140+/-150 K by comparing multi-band photometry with synthetic colors computed from model atmospheres. Additionally, we have been able to obtain an estimate for the age (~320 Myr) and chemical composition ([Fe/H]~0.0) of the binary system through its membership of the Castor moving group. With all these observational constraints, we have carried out a critical test of recent stellar models for low-mass stars. The comparison reveals that most evolutionary models underestimate the radius of the stars by as much as 10%, thus confirming the trend observed by Torres & Ribas (2002) for YY Gem and V818 Tau. In the mass-absolute magnitude diagram, CU Cnc is observed to be dimmer than other stars of the same mass. After ruling out a number of different scenarios, the apparent faintness of CU Cnc can be explained if its components are some 10% cooler than similar-mass stars or if there is some source of circumstellar dust absorption. The latter could be a tantalizing indirect evidence for a coplanar (Vega-like) dusty disk around this relatively young M-type binary.Comment: 14 pages, 5 figures, 6 tables. Accepted for publication in A&A. Tables 1 and 2 available in electronic form at the CDS after publicatio

The field brown dwarf LP 944-20 and the Castor moving group

A reliable age estimation for the field brown dwarf LP 944-20 is accomplished through the analysis of its kinematic properties. The space velocities of this star strongly suggest its membership in the so-called Castor moving group. LP 944-20 can be sensibly assumed to have the group's age, which is estimated to be ~320 Myr, and metal content, which is found to be roughly solar. With these new constrains and the available photometry and lithium abundance, current brown dwarf models are put to a test. Using the IR magnitudes and the lithium diagnostics, the models are able to provide a reasonable description of the brown dwarf's properties (to within a few sigma) but yield an age which is roughly 50% larger than our estimate. Possible reasons for this discrepancy are discussed.Comment: 6 pages, 2 figures, accepted for publication in A&

ASSOCIATION OF DNA REPAIR GENE POLYMORPHISM WITH CHROMOSOMAL ABERRATIONS IN THE BLOOD LYMPHOCYTES OF PATIENTS WITH LUNG CANCER

Analysis of association, between several DNA repair gene polymorphisms and the level of chromosomal aberrations (CAs) in lymphocytes was performed in two groups: a group of 215 patients with lung cancer and a control group of 152 donors. In the group patient with lung cancer the level of CAs shows a significant increase in the carrier of genotypes: XPD TG and XPD GG vs XPD TT. In the control group level of CAs shows a significant increase in the carrier of genotype ADPRT ТС vs ТТ

ANTIBODIES TO BENZO[A]PYRENE IN SERUM OF PATIENTS WITH NON-SMALL CELL LUNG CANCER

The features of immune response to chemical carcinogen benzo[a]pyrene (Bp) at the patients with non-small cell lung cancer (NSCLC) are investigated. The isotypical distinctions in formation of antibodies (Ab) to Bp at the men with NSCLC in comparison with healthy are revealed. There were more often observed the high levels of IgG Ab-Bp at the men with NSCLC. Thus risk of occurrence NSCLC grows almost in 2 times at high levels of Ab-Bp of a class G

THE ASSOCIATION OF IMMUNE RESPONSE TO XENOAND ENDOBIOTIKS AND THEIRS BIOTRANSFORMATION ENZYME GENE POLYMORPHISM WITH CONGENITAL MALFORMATIONS OF THE FETUS

The correlation between immune response to benzo(a)pyrene and progesterone in combination with detoxification enzyme gene polymorphism (CYPIA2*1F and GSTTI) and the occurrence of congenital malformations of the fetus was revealed. It is shown that at high ratio of IgA-antibodies to benzo(a)pyrene and to progesterone in conjunction with the mutant allele of the gene CYPIA2*1F and the deletion genotype of the gene GSTTI chance of the reproductive pathology developing increases to 41 times