Renormalization-group approach to the stochastic Navier--Stokes equation: Two-loop approximation

The field theoretic renormalization group is applied to the stochastic Navier--Stokes equation that describes fully developed fluid turbulence. The complete two-loop calculation of the renormalization constant, the $\beta$ function, the fixed point and the ultraviolet correction exponent is performed. The Kolmogorov constant and the inertial-range skewness factor, derived to second order of the \eps expansion, are in a good agreement with the experiment. The possibility of the extrapolation of the \eps expansion beyond the threshold where the sweeping effects become important is demonstrated on the example of a Galilean-invariant quantity, the equal-time pair correlation function of the velocity field. The extension to the $d$-dimensional case is briefly discussed.Comment: 20 pages, 3 figure

On the stability problem in the O(N) nonlinear sigma model

The stability problem for the O(N) nonlinear sigma model in the 2+\epsilon dimensions is considered. We present the results of the 1/N^{2} order calculations of the critical exponents (in the 2<d<4 dimensions) of the composite operators relevant for this problem. The arguments in the favor of the scenario with the conventional fixed point are given.Comment: 9 pages, revtex, 1 Postscript figur

Premartensitic Transition in Ni2+xMn1-xGa Heusler Alloys

The temperature dependencies of the resistivity and magnetization of a series of Ni2+XMn1-XGa (X = 0 - 0.09) alloys were investigated. Along with the anomalies associated with ferromagnetic and martensitic transitions, well-defined anomalies were observed at the temperature of premartensitic transformation. The premartensitic phase existing in a temperature range 200 - 260 K in the stoichiometric Ni2MnGa is suppressed by the martensitic phase with increasing Ni content and vanishes in Ni2.09Mn0.91Ga composition

Anomalous thermal conductivity of NaV2O5 as compared to conventional spin-Peierls system CuGeO3

A huge increase of thermal conductivity k is observed at the phase transition in stoichiometric NaV2O5. This anomaly decreases and gradually disappears with deviation from stoichiometry in Na(1-x}V2O5 (x = 0.01, 0.02, 0.03, and 0.04). This behavior is compared with that of pure and Zn-doped CuGeO3 where only modest kinks in the k(T) curves are observed at the spin-Peierls transition. The change of k at critical temperature Tc could be partially attributed to the opening of an energy gap in the magnetic excitation spectrum excluding the scattering of thermal phonons on spin fluctuations. However, the reason for such a strong anomaly in the k(T) may lie not only in the different energy scales of CuGeO3 and NaV2O5, but also in the different character of the phase transition in NaV2O5 which can have largely a structural origin, e.g. connected with the charge ordering.Comment: PostScript 4 pages, 4 PostScript pictures. Submitted to Physical Review Letter

O(1/N_f) Corrections to the Thirring Model in 2<d<4

The Thirring model, that is, a relativistic field theory of fermions with a contact interaction between vector currents, is studied for dimensionalities 2<d<4 using the 1/N_f expansion, where N_f is the number of fermion species. The model is found to have no ultraviolet divergences at leading order provided a regularization respecting current conservation is used. Explicit O(1/N_f) corrections are computed, and the model shown to be renormalizable at this order in the massless limit; renormalizability appears to hold to all orders due to a special case of Weinberg's theorem. This implies there is a universal amplitude for four particle scattering in the asymptotic regime. Comparisons are made with both the Gross-Neveu model and QED.Comment: 22 pages in plain TeX, with 7 figs included using psfig.tex (Minor conceptual changes - algebra unaffected

Integral Transforms for Conformal Field Theories with a Boundary

A new method is developed for solving the conformally invariant integrals that arise in conformal field theories with a boundary. The presence of a boundary makes previous techniques for theories without a boundary less suitable. The method makes essential use of an invertible integral transform, related to the radon transform, involving integration over planes parallel to the boundary. For successful application of this method several nontrivial hypergeometric function relations are also derived.Comment: 20 pagess, LateX fil

Relationships of nosological form of the primary and second neoplasms in oncological patients

ЗЛОКАЧЕСТВЕННЫЕ НОВООБРАЗОВАНИЯНОЗОЛОГИЧЕСКИЕ ФОРМЫ РАКАЗАБОЛЕВАЕМОСТЬ, ЧАСТОТА СЛУЧАЕВУКРАИНАЦель. Исследование зависимости между нозологическими формами первых и вторых раков у пациентов, которые проходили специальное лечение по поводу онкологического заболевания и у которых возникли вторые раки через 3 года и более после окончания лечения. Материал и методы. В исследовании проводилось сравнение между нозологической структурой вторых раков, которые возникли у 203 пациентов, проходивших лечение по поводу онкологической патологии, и официальными данными об удельном весе 10 основных нозологических форм злокачественных новообразований населения Украины. Статистическая значимость полученных результатов оценивалась с помощью доверительных интервалов, нормированных с учетом специфики контингента пациентов клиники, где проводилось исследование. Результаты. В соответствии с удельным весом нозологических форм первых раков, обусловленных, в первую очередь, специализацией клиники, обследуемые группы пациентов были разделены на 5 нозологических подгрупп: пациенты с раком молочной железы, щитовидной железы, тела матки, шейки матки, рак яичников и с иными формами рака. Для каждой из подгрупп была исследована нозологическая структура вторых раков и сопоставлена с общей структурой злокачественных новообразований по данным официальной статистики. Показано, что частота пяти выделенных нозологических форм, рассчитанных для клиники, достаточно хорошо соответствует популяционному среднему, при этом для двух наиболее представительных нозологических форм соответствие находится в пределах ожидаемой стохастической изменчивости. Таким образом, показано, что не существует статистически значимых различий между процентным составом 10 основных нозологических форм рака населения Украины и структурой нозологических форм вторых раков у исследуемой группы пациентов. Заключение. Нозологическая форма вторых раков не является следствием первого рака, а воспроизводит общую нозологическую структуру заболеваемости злокачественными новообразованиями.Objective. To investigate the relationship between nosological forms of the primary and second neoplasms in patients who have undergone special treatment for cancer, and who have developed second neoplasms three and more years after the end of treatment. Methods. The study has compared the nosological structure of second neoplasms that developed in 203 patients undergoing treatment for oncological pathology with the official data on the specific weight of 10 major nosological forms of malignant neoplasms in Ukraine. The statistical significance of the obtained results has been estimated using confidence intervals normalized taking into account the specificity of the patients of the clinic where the study was conducted. Results. In accordance with the specific weight of the nosological forms of the primary neoplasms, conditioned first by the specialization of the clinic, the study groups were divided into 5 nosological subgroups: patients with breast, thyroid, uterine, cervical, ovarian, and subgroup with other forms of cancer. For each of the subgroups, the nosological structure of the second neoplasms was investigated and compared with the overall structure of malignant neoplasms according to the official statistics. It is shown that the frequencies of five allocated nosological forms calculated for the clinic correspond fairly well to the population mean, while for two most representative nosological forms the correspondence is within the expected stochastic variability. Thus, it has been demonstrated that there are no statistically significant differences between the percentage composition of 10 major nosological forms of cancer in Ukraine and the structure of nosological forms of second neoplasms in the study group of patients. Conclusions. The nosological form of second neoplasms is not a consequence of the primary cancer, but reproduces the overall nosological structure of the incidence of malignant neoplasms

High frequency ESR investigation on dynamical charge disproportionation and spin gap excitation in NaV_2O_5

A significant frequency dependence of the ESR line width is found in NaV_2O_5 between 34-100 K and the line width increases as the resonance frequency is increased from 95 GHz to 760 GHz. The observed frequency dependence is qualitatively explained in terms of the dynamical charge disproportionation. The present results show the essential role of the internal charge degree of freedom in a V-O-V bond. We have also proposed the existence of the Dzyaloshinsky-Moriya interaction in the low temperature charge ordered phase considering the breaking of the selection rule of ESR realized as the direct observation of the spin gap excitation.Comment: 9 figures submitted to J. Phys.Soc. Jp