On pp-index extremal groups

The question on connection between the structure of a finite group $G$ and the properties of the indices of elements of $G$ has been a popular research topic for many years. The $p$-index $|x^G|_p$ of an element $x$ of a group $G$ is the $p$-part of its index $|x^G|=|G:C_G(x)|$. The presented short note describes some new results and open problems in this direction, united by the concept of the $p$-index of a group element

On recognition of direct powers of finite simple linear groups by spectrum

The spectrum of a finite group is the set of its element orders. We give an affirmative answer to Problem 20.58(a) from the Kourovka Notebook proving that for every positive integer $k$, the $k$-th direct power of the simple linear group $L_{n}(2)$ is uniquely determined by its spectrum in the class of finite groups provided $n$ is a power of $2$ greater than or equal to $56k^2$.Comment: 17 page

Providing energy decoupling of electric drive and electric grids for industrial electrical installations

Subjects of the research are industrial electric drives, witch maintain the operation of main actuating units of production machines and installations during the development of mineral resource deposits. The goal is to research the possibility to ensure the energy decoupling of industrial electric drives and electric grid by means of structural implementation of active rectifiers into frequency converters. The main purpose of energy decoupling is to eliminate the negative impact of low quality electric energy and changes in energy parameters on electric drive operation. In order to accomplish energy decoupling of electric drive with active rectifier, methods of mathematical and simulation modeling with mathematical application software package were used. The integrated simulation model with two electric drives, including active rectifier (energy decoupled electric drive) and diode rectifier (standard type electric drive), were created. Simulation model is provided with tools for oscillographic testing and analysis of the impact of power quality parameters on frequency converters and drive motors operation. The analysis of effectiveness of energy decoupling by means of active rectifier of frequency converter shows that drive motor completely retains the stability and controllability of rotation frequency and torque during the changes of power quality parameters in electric grid. The use of active rectifier allows to ensure the operation of electric drive in required mode in case of voltage decrease by 30 % with normative value of 5-10 %, i.e. energy decoupling provides high stability margin for voltage. Electric drive with active rectifier ensures energy decoupling in case of asymmetry of supply voltage. The control of mechanical variables of induction motor during offsets in amplitude and frequency in all phases of electric grid is ensured to be on required level

Enhancement of the Thermal Conductivity in gapped Quantum Spin Chains

We study mechanism of magnetic energy transport, motivated by recent measurements of the thermal conductivity in low dimensional quantum magnets. We point out a possible mechanism of enhancement of the thermal conductivity in gapped magnetic system, where the magnetic energy transport plays a crucial role. This mechanism gives an interpretation for the recent experiment of CuGeO_3, where the thermal conductivity depends on the crystal direction.Comment: 4 pages, 2 figure

Gravitational Couplings of Intrinsic Spin

The gravitational couplings of intrinsic spin are briefly reviewed. A consequence of the Dirac equation in the exterior gravitational field of a rotating mass is considered in detail, namely, the difference in the energy of a spin-1/2 particle polarized vertically up and down near the surface of a rotating body is $\hbar\Omega\sin\theta$. Here $\theta$ is the latitude and $\Omega = 2GJ/(c^2 R^3)$, where $J$ and $R$ are, respectively, the angular momentum and radius of the body. It seems that this relativistic quantum gravitational effect could be measurable in the foreseeable future.Comment: LaTeX file, no figures, 16 page

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

Helioseismology, solar models and neutrino fluxes

We present our results concerning a systematical analysis of helioseismic implications on solar structure and neutrino production. We find Y$_{ph}=0.238-0.259$, $R_b/R_\odot=0.708-0.714$ and $\rho_b=(0.185-0.199)$ gr/cm$^3$. In the interval $0.2<R/R_\odot<0.65$, the quantity $U=P/\rho$ is determined with and accuracy of $\pm 5$\permille~or better. At the solar center still one has remarkable accuracy, $\Delta U/U <4$. We compare the predictions of recent solar models (standard and non-standard) with the helioseismic results. By constructing helioseismically constrained solar models, the central solar temperature is found to be $T=1.58 \times 10^7$K with a conservatively estimated accuracy of 1.4%, so that the major unceratainty on neutrino fluxes is due to nuclear cross section and not to solar inputs.Comment: 14 pages including 9 figures, LaTex file, espcrc2.sty is needed; to appear in Nucl. Phys. B Proc. Suppl., Proceedings of TAUP97 conference, Laboratori Nazionali del Gran Sasso, September 199

Strong damping of phononic heat current by magnetic excitations in SrCu_2(BO_3)_2

Measurements of the thermal conductivity as a function of temperature and magnetic field in the 2D dimer spin system SrCu$_2$(BO$_3$)$_2$ are presented. In zero magnetic field the thermal conductivity along and perpendicular to the magnetic planes shows a pronounced double-peak structure as a function of temperature. The low-temperature maximum is drastically suppressed with increasing magnetic field. Our quantitative analysis reveals that the heat current is due to phonons and that the double-peak structure arises from pronounced resonant scattering of phonons by magnetic excitations.Comment: a bit more than 4 pages, 2 figures included; minor changes to improve the clarity of the presentatio