Fiske Steps and Abrikosov Vortices in Josephson Tunnel Junctions

We present a theoretical and experimental study of the Fiske resonances in the current-voltage characteristics of "small" Josephson junctions with randomly distributed misaligned Abrikosov vortices. We obtained that in the presence of Abrikosov vortices the resonant interaction of electromagnetic waves, excited inside a junction, with the ac Josephson current manifests itself by Fiske steps in a current-voltage characteristics even in the absence of external magnetic field. We found that the voltage positions of the Fiske steps are determined by a junction size, but the Fiske step magnitudes depend both on the density of trapped Abrikosov vortices and on their misalignment parameter. We measured the magnetic field dependence of both the amplitude of the first Fiske step and the Josephson critical current of low-dissipative small $Nb$ based Josephson tunnel junctions with artificially introduced Abrikosov vortices. A strong decay of the Josephson critical current and a weak non-monotonic decrease of the first Fiske step amplitude on the Abrikosov vortex density were observed. The experimentally observed dependencies are well described by the developed theory.Comment: 21 pages, 7 figures, submitted to Physical Review

Features of exogenous development of Trichuris globulosa (Nematoda, Trichuridae)

Parasitic nematodes of the genus Trichuris Röderer, 1761 are hematophagous helminths, capable of parasitizing many different hosts including humans. The domestic and wild ruminants are hosts of several Trichuris species, with Trichuris globulosa (Linstow, 1901) one of the most prevalent parasites found in cattle. The exogenous stages of the helminth’s life cycle develop in the outer environment, and their activity and survival depend on the abiotic factors. Thus the aim of the work was to determine the influence of temperature on the rate and success of development of infectious eggs of T. globulosa in laboratory culture considering their morphological and metric changes. The results of experimental studies showed that the embryogenesis of T. globulosa eggs, cultured in laboratory conditions and obtained from gonads of female nematodes, occurs in six stages regardless of the temperature regime. At the same time, the rate of transition from one stage to another, the term for the formation of infectious eggs and their viability directly depends on the temperature of the external environment. At the optimal temperature for the development of T. globulosa eggs, 25 °C, 76.3% of eggs reached the mobile larva stage. A decrease in temperature to 20 °C and an increase to 30° C led to an increase in the egg mortality of up to 26% and 32%, respectively, and the viability of eggs decreased. Under such temperature conditions, 74% and 68% of eggs of Trichuris reached the mobile larva stage. With an increase in the culture temperature, the time of embryogenesis decreased and amounted to 56 days at 20 °C, 48 days at 25 °C, and 32 days at 30 °C. Depending on the temperature regime, the zygote stage lasted from the release of eggs from the gonads of female nematodes to 12 days, the stage of blastomere formation from 4 to 12 days, the stage of the bean-shaped embryo from 8 to 24 days, the stage of the tadpole embryo from 16 to 36 days, the stage of larval formation lasted from 16 to 48 days, the stage of mobile larva from days 20 to 56. The formation of the infectious T. globulosa egg from a non-infectious one is shown in an experiment to include the metric changes confirmed by metric indicators. Mature eggs with a mobile larva are shorter and wider, with shorter and narrower plugs and a thinner shell than eggs at the zygote stage. The obtained research results on the influence of temperature on the exogenous development of Trichuris globulosa will make it possible to predict the epizootic situation of trichurosis in animal husbandry, as well as take timely measures to arrest the embryonic stages of nematode development in the external environment

APPLICATION OF THE INTERACTIVE METHODS IN STUDENT-CENTERED HIGH SCHOOL EDUCATION

The article deals with the problem of the need to improve the level of methodological preparation of professional activities of teachers in higher education. Interactive teaching methods, which have been developing intensively lately, more actively contribute to this. Due to the self-sufficient activity and group interaction inherent in their essence, they can be useful and promising for both teachers and students. The author reveals the popular forms and methods of interactive learning in the article. Also highlights the main advantages and disadvantages of this technology. A brief overview of group work using interactive teaching methods in higher education.Keywords: university, technology, interactive learning, teacher, pedagogical skills, student. В статье рассмотрена проблема необходимости повышения уровня методической подготовки профессиональной деятельности преподавателя в высшей школе. Лучше способствуют этому интерактивные методы обучения, которые интенсивно разрабатываются в последнее время. Благодаря заложенным в их суть самостоятельной деятельности и групповом взаимодействии, они могут быть полезными и перспективными как для преподавателя, так и для студентов. Авторы раскрывают в статье популярные формы и методы интерактивного обучения. Также подчеркиваются основные преимущества и недостатки данной технологии. Кратко приведен обзор групповой работы с использованием интерактивных методов обучения в высшей школе.Ключевые слова: высшая школа, технология, интерактивное обучение, преподаватель, педагогическое мастерство, студент. У статті розглянуто проблему необхідності підвищення рівня методичної підготовки професійної діяльності викладача у вищій школі. Якнайкраше сприяють цьому інтерактивні методи навчання, що активно розробляються останнім часом. Завдяки закладеним в їх суть самостійній діяльності та груповій взаємодії, вони можуть бути корисними та перспективними як для викладача, так і для студентів. Автори розкривають у статті найпопулярніші форми і методи інтерактивного навчання. Також підкреслюються основні переваги та недоліки даної технології. Стисло наведено огляд групової роботи з використанням інтерактивних методів навчання у вищій школі.Ключові слова: вища школа, технологія, інтерактивне навчання, викладач, педагогічна майстерність, студент

Laser Scanning Microscopy of HTS Films and Devices

The work describes the capabilities of Laser Scanning Microscopy (LSM) as a spatially resolved method of testing high_Tc materials and devices. The earlier results obtained by the authors are briefly reviewed. Some novel applications of the LSM are illustrated, including imaging the HTS responses in rf mode, probing the superconducting properties of HTS single crystals, development of twobeam laser scanning microscopy. The existence of the phase slip lines mechanism of resistivity in HTS materials is proven by LSM imaging.Comment: 17 pages, 21 figures, Submitted to Fizika Nizkikh Temperatur (Low Temperature Physics

The effect of <i>OPRM1, ABCB1, IL1B, PTGS2, LOC 541472</i> gene polymorphism on the variability of chronic pain syndrome in patients with pancreatic cancer

Background. One of the obligate clinical manifestations of pancreatic cancer is chronic pain syndrome, which is realized in 80 % of patients with a progressive course of the disease. Studying the molecular genetic factors that influence the phenotypic realization of chronic pain syndrome in patients with pancreatic cancer is an important step towards personalizing the roadmap.Aims. To study the associative effect of single nucleotide polymorphisms (SNPs) of the OPRM1, ABCB1, IL1B, PTGS2, LOC 541472 genes on the interindividual variability of chronic pain syndrome in patients with pancreatic cancer.Materials and methods. The study included 81 patients aged 18 to 75 years with histological verification, promptly treated for prostate cancer according to the main criterion for inclusion in the study. Molecular genetic studies were performed to determine the allelic variants of rs1799971 of the OPRM1 gene, rs1045642, rs2032582, rs1128503 of the ABCB1 gene, rs1143627 of the IL1B gene, rs5275 of the PTGS2 gene, rs1800795 of the LOC gene 541472. Statistical processing of the results was carried out using the Statistica 10.0 program.Results. Carriers of the homozygous AA genotype of the OPRM1 gene prevailed among the observed patients of the Krasnoyarsk Territory with pancreatic cancer. Genotype AG IL1B showed an increase in the chances of chronic pain by 18,46 times in patients with pancreatic cancer. Carriers of the GG genotypes of the ABCB1 rs1045642 and AA genes of the ABCB1 rs2032582 gene constituted a risk group for the implementation of chronic pain in patients with pancreatic cancer.Conclusions. The study showed that the most significant in terms of increasing the chances of chronic pain in patients with pancreatic cancer are the homo- and heterozygous genotypes of the IL1B and LOC 541472 genes encoding IL-6

Dzyaloshinskii--Moriya interaction: How to measure its sign in weak ferromagnetics?

Three experimental techniques sensitive to the sign of the Dzyaloshinskii--Moriya interaction are discussed: neutron diffraction, Moessbauer gamma-ray diffraction, and resonant x-ray scattering. Classical examples of hematite (alpha-Fe2O3) and MnCO3 crystals are considered in detailComment: 5 pages, 1 figure; to be published in JETP Letter

Microwave Current Imaging in Passive HTS Components by Low-Temperature Laser Scanning Microscopy (LTLSM)

We have used the LTLSM technique for a spatially resolved investigation of the microwave transport properties, nonlinearities and material inhomogeneities in an operating coplanar waveguide YBa_2Cu_3O_{7-\delta} (YBCO) microwave resonator on an LaAlO_3 (LAO) substrate. The influence of twin-domain blocks, in-plane rotated grains, and micro-cracks in the YBCO film on the nonuniform rf current distribution were measured with a micrometer-scale spatial resolution. The impact of the peaked edge currents and rf field penetration into weak links on the linear device performance were studied as well. The LTLSM capabilities and its future potential for non-destructive characterization of the microwave properties of superconducting circuits are discussed.Comment: 8 pages, 9 figures, 2-column format, presented at High Temperature Superconductors in High Frequency Fields 2004, Journal of Superconductivity (in press

Методы синтеза согласующих цепей для широкополосных радиотехнических устройств c нестабильным импедансом нагрузки

The aim of this work is to select a synthesis method for a broadband matching circuit that provides maximum power transfer from a signal source to a load in the presence of a changing load impedance of a radio engineering device. To achieve this goal, an analysis of the main directions of designing broadband matching circuits (analytical, numerical, graphic-analytical synthesis methods) was carried out. Based on the results of a comparison of synthesis methods, their features (advantages and disadvantages) were indicated. The analysis of methods of synthesis of broadband matching circuits was carried out. For the analysis, the generalized Darlington method, the method of real frequencies, the structural-parametric synthesis method based on the T-matrix apparatus, and the graphic-analytical method based on the Volpert-Smith diagram were chosen). Using these synthesis methods, broadband matching circuits were obtained for various types of loads. Comparison of the results obtained was carried out according to several indicators: the level of the power transfer coefficient in the operating frequency range, the sensitivity of the power transfer coefficient to the change in the ratings of the elements of the matching circuit and the load impedance, provided that the number of elements of the matching circuit is no more than six. Based on the comparison and analysis, it was found that the most preferable synthesis method for solving the problem posed is the method of real frequencies. Its advantage is the use of a combination approach (iterative determination of the parameters of the resistance function with an analytical representation of the transfer function). Matching circuits obtained using this synthesis method provided the highest level of power transmission coefficient, as well as the lowest sensitivity value in a given frequency band for the considered types of loads.Целью работы является выбор метода синтеза широкополосной согласующей цепи, обеспечивающей максимальную передачу мощности от источника сигнала в нагрузку при наличии изменяющегося импеданса нагрузки радиотехнического устройства. Для достижения поставленной цели был осуществлен анализ основных направлений проектирования широкополосных согласующих цепей (аналитические, численные, графоаналитические методы синтеза). По результатам сравнения методов синтеза были указаны их особенности (достоинства и недостатки). Был выполнен анализ методов синтеза широкополосных согласующих цепей. Для анализа были выбраны обобщенный метод Дарлингтона, метод вещественных частот, структурно-параметрический метод синтеза на основе аппарата Т-матрицы, графоаналитический метод на основе диаграммы Вольперта – Смитта. С помощью данных методов синтеза были получены широкополосные согласующие цепи применительно к различным типам нагрузок. Сопоставление полученных результатов осуществлялось по нескольким показателям: уровню коэффициента передачи мощности в рабочем диапазоне частот, чувствительности коэффициента передачи по мощности к изменению номиналов элементов согласующей цепи и импедансу нагрузки при условии, что количество элементов согласующей цепи не более шести. На основании проведенного сравнения и анализа методов синтеза было установлено, что для решения поставленной задачи наиболее предпочтительным является метод вещественных частот. Его достоинством является использование комбинационного подхода (итеративного нахождения параметров функции сопротивления с аналитическим представлением функции передачи). Согласующие цепи, полученные с помощью данного метода синтеза, обеспечили наибольший уровень коэффициента передачи по мощности, а также наименьшее значение чувствительности в заданной полосе частот для рассматриваемых типов нагрузок

Состав отходящих газов при каталитическом синтезе углеродных наноматериалов при пиролитическом разложении пропан-бутановой смеси

It is known that during the process of carbon nanomaterials synthesis, gaseous products and various unknown hydrocarbons are formed. Thus, the production of carbon nanomaterials could damage the environment. A detailed analysis of all gaseous products during the pyrolysis process is needed in order to clarify the nature of the formed substances and to control the technological characteristics of the catalyst. The chemical composition study of exhaust gases was made on the facility of propane-butane mixture pyrolysis for the carbon nanomaterial synthesis. The analysis of 16 polycyclic aromatic hydrocarbons (PAHs) of the extracts is made using a gas chromatography-mass spectrometry method. A quantitative analysis of gases was made by gas chromatography coupled with a heat conduction detector and a flame ionization detector. It was established that the concentrations of some PAHs exceed 14, 20, 90 and 100 times much as a maximum permissible concentration in the air. It was found that the appropriate devices of carbon nanomaterial production should be used in order to eliminate the PAHs that are formed.Анализ отходящих газов установки пиролиза легких углеводородов в процессе синтеза углеродных наноматериалов является актуальной задачей не только для оценки количества образующихся вредных веществ, но и для обеспечения наибольшей производительности реактора и максимальной степени конверсии исходного сырья. Методом газовой хроматографии проведен качественный и количественный анализ отходящих газов: неконденсируемых газообразных фракций и адсорбируемых ароматических углеводородов. В результате экспериментов было установлено, что основными компонентами отходящих газов являются водород и метан. В соответствии с утвержденной в Республике Беларусь методикой измерены значения 16 полициклических ароматических углеводородов, обнаруженных в отходящих газах. Проведено сравнение полученных значений с нормативными предельно допустимыми концентрациями канцерогенов в воздухе. Установлено, что концентрации пирена, фенантрена, аценафтилена, аценафтена превышают норму в 1,5–6 раз, а содержание таких токсикантов, как бенз(а)антрацен, антрацен, бенз(а)пирен и дибенз(а,h)антрацен значительно превышают норму. Полученная информация позволяет оценить степень опасности для экологии и возможный вклад таких установок в загрязнение окружающей среды, а также прогнозировать защитные меры по снижению вредного воздействия