863 research outputs found

    The Importance of the Study of the Hemodynamics of the Uterine Tumors by the Method of Dopplerometry in the Two- and Three-dimensional Echography Modes for Differential Diagnostics of Simple, Proliferating Leiomyomas and Uterine Sarcomas (Review of Litera

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    The article analyzes modern literature data on the importance of studying the hemodynamics of uterine tumors with dopplerometry in two - and three - dimensional regimens of echography for differential diagnosis of simple proliferating leiomyomas and sarcomas of the uterus. It is shown that the differential diagnosis of benign and Malignant tumors using the dopplerometry is based on various features of the blood supply of these tumors. On the basis of the analysis of literature data, it was concluded that in the dopplerometry evaluation of benign, borderline and Malignant tumors of myometrium in the two-dimensional regime, there were differences in the localization of the detected vessels in the CDM regimen, in the rates of vascular blood flow and vascular resistance in pulse dopplerometry. For a simple leiomyoma, the absence of a central intra-node localization of blood vessels in the CDM regimen, a low rate of arterial and venous blood flow, as well as an average resistance of arterial blood flow in the regime of impulsive dopplerometry are most typical; in a leiomyoma with eating disorders, the absence of a central intra-node localization of blood vessels, a low rate of arterial and venous blood flow in combination with high arterial resistance were more often observed. For the proliferating leiomyoma, the central intra-node localization of the vessels and the average blood flow velocities with low and medium resistance are characteristic. For sarcoma of the uterus, there is abundant vascularization both around the periphery and in the center, high blood flow rates and low resistance. The authors emphasize that there is information about the low specificity of this gradation, since the detection of a central type of vascularization and low resistance values can be in simple myomatous nodes with edema, eating disorders and destruction, and leads to diagnostic errors and suspicion of Malignancy. In the three-dimensional dopplerometry mode for simple leiomyomas, low indices of volume perfusion indices were characteristic, and for proliferating leiomyomas and sarcomas of the uterus – high indices of volume perfusion indices exceeding those in the uterus as a whole.Based on the review of the literature, the authors concluded that the presently available echographic and dopplerometric two- and three-dimensional markers are characterized by high sensitivity, but very low specificity. The low specificity of the known ultrasonic and dopplerometric criteria combined with the rarity of cases of sarcoma in the uterus against the background of a large number of similar echographically and dopplerometrically leiomyomas lead to low diagnostic accuracy of ultrasound diagnostics. This situation requires a further continuation of the scientific search for differential diagnostic ultrasound criteria by leiomyomas and sarcomas of the uterus using modern technologies, including three-dimensional echography

    Hopf Term for a Two-Dimensional Electron Gas

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    In this Comment on the paper by W. Apel and Yu. A. Bychkov, cond-mat/9610040 and Phys. Rev. Lett. 78, 2188 (1997), we draw attention to our prior microscopic derivations of the Hopf term for various systems and to shortcomings of the Apel-Bychkov derivation. We explain how the value of the Hopt term prefactor Θ\Theta is expressed in terms of a topological invariant in the momentum space and the quantized Hall conductivity of the system. (See also related paper cond-mat/9703195)Comment: RevTeX, 1 page, no figure

    Energy spectrum of graphene multilayers in a parallel magnetic field

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    We study the orbital effect of a strong magnetic field parallel to the layers on the energy spectrum of the Bernal-stacked graphene bilayer and multilayers, including graphite. We consider the minimal model with the electron tunneling between the nearest sites in the plane and out of the plane. Using the semiclassical analytical approximation and exact numerical diagonalization, we find that the energy spectrum consists of two domains. In the low- and high-energy domains, the semiclassical electron orbits are closed and open, so the spectra are discrete and continuous, correspondingly. The discrete energy levels are the analogs of the Landau levels for the parallel magnetic field. They can be detected experimentally using electron tunneling and optical spectroscopy. In both domains, the electron wave functions are localized on a finite number of graphene layers, so the results can be applied to graphene multilayers of a finite thickness.Comment: 11 pages, 13 figures. Added to v.2: Appendix A, Fig. 13, Refs. [18-23]. V.3: minor stylistic corrections from the published versio

    LABOR EDUCATION OF PRESCHOOL CHILDREN: RETROSPECTIVE ANALYSIS

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    В данной статье рассматриваются вопросы организации трудового воспитания детей дошкольного возраста от времён Киевской Руси до начала ХХ века. Доказано, что становлению вопросов трудового воспитания детей дошкольного возраста способствовали: труды отечественных (Владимир Мономах, И. Гизель, И. Посошков, Г. Сковорода, В. Одоевский, К. Ушинский, Л. Толстой, Е. Водовозова, К. Вентцель) педагогов, организация педагогических музеев, летних детских «колоний», клубов и детских площадок, проведение Киевским обществом народных детских садов выставки «Дошкольное воспитание» и «Детский труд», организация магазина «Дошкольное воспитание», массовый выпуск отечественной педагогической литературы, издание педагических журналов.Ключевые слова: трудовое воспитание, дети дошкольного возраста, организация, анализ, становление.This article is devoted to the issues of the organization of labor education of preschool children from the time of Kievan Rus to the beginning of the XXth  century. It has been proved that the formation of questions about labor education of preschool children was facilitated by: works of native (Vladimir Monomakh, I. Gizel, I. Pososhkov, G. Skovoroda, V. Odoyevskiy, K. Ushynskiy, L. Tolstoy, Ye. Vodovozova, K. Ventsel) teachers, the organization of pedagogical museums, summer children «colonies», clubs and playgrounds, exhibitions «Preschool education» and «Children labor» made by the Kiev Society of Folk Kindergartens, the organization of the store «Preschool education», mass production of native pedagogical literature, publishing pedagogical magazines.Keywords: labor education, preschool children, organization, analysis, formation

    Curie law, entropy excess, and superconductivity in heavy fermion metals and other strongly interacting Fermi liquids

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    Low-temperature thermodynamic properties of strongly interacting Fermi liquids with fermion condensate are investigated. We demonstrate that the spin susceptibility of these systems exhibits the Curie-Weiss law, and the entropy contains a temperature-independent term. The excessive entropy is released at the superconducting transition, enhancing the specific heat jump Delta C and rendering it proportional to the effective Curie constant. The theoretical results are favorably compared with the experimental data on the heavy fermion metal CeCoIn5, as well as He-3 films.Comment: 4 pages, 2 figures. V.2: a reference added; minor changes as in the published versio

    Detecting D-Wave Pairing and Collective Modes in Fermionic Condensates with Bragg Scattering

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    We show how the appearance of d-wave pairing in fermionic condensates manifests itself in inelastic light scattering. Specifically, we calculate the Bragg scattering intensity from the dynamic structure factor and the spin susceptibility, which can be inferred from spin flip Raman transitions. This information provides a precise tool with which we can identify nontrivial correlations in the state of the system beyond the information contained in the density profile imaging alone. Due to the lack of Coulomb effects in neutral superfluids, this is also an opportunity to observe the Anderson-Bogoliubov collective mode
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