3,294 research outputs found

    Sintering oxide ceramics based on AI[2]O[3] and ZrO[2], activated by MgO, TiO[2] and SiO[2] additives

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    The positive effect of the addition of MgO and TiO[2] in an amount of no more than 1 wt. % on sintering and physico-mechanical properties of alumina ceramics is established. Addition of 5% of SiO[2] to A1[2]O[3] provides the mechanism of liquid phase sintering of ceramics, which leads to increase in its density and strength up to 480 MPa. In ceramic system A1[2]O[3] - ZrO[2] - Y[2]O[3] highest level of physical and mechanical properties of the composition had a hypereutectic composition 16.6% A1[2]O[3] - 76% Z1O[2] - 7.4% Y[2]O[3]. In this composition two mechanisms of hardening are realized simultaneously, such as transformational hardening by t-m -ZrO[2] transition and dispersion strengthening with high-modulus particles of [alpha]- A1[2]O[3]

    Stromal and Tumor Glioma-Derived Cells with Similar Characteristics have Differences in α-Smooth Muscle Actin Expression and Localization

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    Gliomas are solid brain tumors composed of tumor cells and recruited heterogenic stromal components. The study of the interactions between the perivascular niche and its surrounding cells is of great value in unraveling mechanisms of drug resistance in malignant gliomas. In this study, we isolated the stromal diploid cell population from oligodendroglioma and a mixed population of tumor aneuploid and stromal diploid cells from astrocytoma specimens. The stromal cells expressed neural stem/progenitor and mesenchymal markers showing the same discordant phenotype that is typical for glioma cells. Moreover, some of the stromal cells expressed CD133. For the first time, we demonstrated that this type of stromal cells had the typical myofibroblastic phenotype as the α-SMA+ cells formed α-SMA fibers and exhibited the specific function to deposit extracellular matrix (ECM) proteins at least in vitro. Immunofluorescent analysis showed diffuse or focal α-SMA staining in the cytoplasm of the astrocytoma-derived, A172, T98G, and U251MG glioma cells. We could suggest that α-SMA may be one of the main molecules, bearing protective functions. Possible mechanisms and consequences of α-SMA disruptions in gliomas are discussed

    Directions of Convergence of the Requirements of the Main Domestic Standard for the Design of Concrete and Reinforced Concrete Structures SP 63.13330.2012 with the Requirements of the International Standard ISO 19338

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    Design standards on building structures should contain, first of all, the performance and assessment requirements of structures. At the same time, design standards should provide the possibility for design and construction of concrete and reinforced concrete parts of buildings and structures that meet the requirements of the Technical regulations "On the safety of buildings and structures". Taking into account the importance of ensuring the reliability and safety of buildings and structures erected with the use of structural concrete, the technical Committee of the international organization for standardization ISO TC 71 "Concrete, reinforced concrete and prestressed concrete", certifies national standards for compliance with the requirements of the international standard ISO 19338 "Performance and Assessment Requirements for Design Standards on Structural Concrete", developed by the same Committee. The standard describes the issues that should be included in the standards for the design of concrete and reinforced concrete structures (terms and definitions, basic requirements, performance requirements,loads and impacts, design estimates, requirements for manufacturing and construction, as well as quality control). These requirements are common to all standards in the design of concrete and reinforced concrete structures. In this regard, it is relevant and important to establish the possibility of presenting the National Code of rules SP 63.13330.2012 "SNiP 52.01-2003 Plain and Reinforced Concrete Structures. General Provisions" for certification for compliance with the requirements of ISO 19338. To achieve this goal, the relevant work has been done, based on the results of which were made the proposals for the submission of SP 63.13330.2012 for certification for compliance with ISO 19338:2014. These proposals are set out in the text of the article

    The Standard Model Prediction of the Muon Anomalous Magnetic Moment

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    This article reviews and updates the Standard Model prediction of the muon g-2. QED, electroweak and hadronic contributions are presented, and open questions discussed. The theoretical prediction deviates from the present experimental value by 2-3 standard deviations, if e+e- annihilation data are used to evaluate the leading hadronic term.Comment: 30 pages, 8 figures. v2: Updated version to appear in J.Phys.G. Comments and references added, typo corrected in eq.(17

    Ultrabright single-photon emission from germanium-vacancy zero-phonon lines: deterministic emitter-waveguide interfacing at plasmonic hot spots

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    Striving for nanometer-sized solid-state single-photon sources, we investigate atom-like quantum emitters based on single germanium-vacancy (GeV) centers isolated in crystalline nanodiamonds (NDs). Cryogenic characterization indicated symmetry-protected and bright (>106 counts/s with off-resonance excitation) zero-phonon optical transitions with up to 6-fold enhancement in energy splitting of their ground states as compared to that found for GeV centers in bulk diamonds (i.e. up to 870 GHz in highly strained NDs vs. 150 GHz in bulk). Utilizing lithographic alignment techniques, we demonstrate an integrated nanophotonic platform for deterministic interfacing plasmonic waveguides with isolated GeV centers in NDs, which enables 10-fold enhancement of single-photon decay rates along with the emission direction control by judiciously designing and positioning a Bragg reflector. This approach allows one to realize the unidirectional emission from single-photon dipolar sources, thereby opening new perspectives for the realization of quantum optical integrated circuits

    Boosting Local Field Enhancement by on-Chip Nanofocusing and Impedance-Matched Plasmonic Antennas

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    Strongly confined surface plasmon-polariton modes can be used for efficiently delivering the electromagnetic energy to nano-sized volumes by reducing the cross sections of propagating modes far beyond the diffraction limit, i.e., by nanofocusing. This process results in significant local-field enhancement that can advantageously be exploited in modern optical nanotechnologies, including signal processing, biochemical sensing, imaging and spectroscopy. Here, we propose, analyze, and experimentally demonstrate on-chip nanofocusing followed by impedance-matched nanowire antenna excitation in the end-fire geometry at telecom wavelengths. Numerical and experimental evidences of the efficient excitation of dipole and quadrupole (dark) antenna modes are provided, revealing underlying physical mechanisms and analogies with the operation of plane-wave Fabry-P\'erot interferometers. The unique combination of efficient nanofocusing and nanoantenna resonant excitation realized in our experiments offers a major boost to the field intensity enhancement up to 12000\sim 12000, with the enhanced field being evenly distributed over the gap volume of 30×30×10 nm330\times 30\times 10\ {\rm nm}^3, and promises thereby a variety of useful on-chip functionalities within sensing, nonlinear spectroscopy and signal processing

    ОСОБЕННОСТИ ТЕЧЕНИЯ ФИБРИЛЛЯЦИИ ПРЕДСЕРДИЙ У ПАЦИЕНТОВ С КОМОРБИДНОСТЬЮ В ЗАВИСИМОСТИ ОТ ПРОВОДИМОЙ ТЕРАПИИ

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    Aim. To study the clinical course of atrial fibrillation in patients with arterial hypertension and extracardiac comorbid pathology depending on the administered therapy.Methods. 207 men aged 45–65 years with atrial fibrillation (paroxysmal and persistent) and arterial hypertension in combination with diabetes mellitus (n = 40), abdominal obesity (n = 64) and chronic obstructive pulmonary disease (n = 47) were recruited to a observational cohort study. 56 patients with atrial fibrillation and arterial hypertension but without any extracardiac diseases were included in the comparison group. Clinical and anthropometric parameters were assessed in all patients. Adherence to therapy was estimated with the Morisky-Green test. All patients underwent ECG; electrocardiographic holter monitoring, 24-hour blood pressure monitoring with the Daily Monitoring Systems SCHILLER (Schiller, Switzerland), 2D and M-mode echocardiography using a Vivid 7 device (General Electric, USA). The statistical analysis was performed in the Rstudio software (version 0.99.879, RStudio, Inc., MA, USA).Results. 66% of patients with atrial fibrillation and arterial hypertension had concomitant extracardiac comorbid pathology, of them 20% of had diabetes mellitus, 22% with chronic obstructive pulmonary disease, and 24% with abdominal obesity. The clinical groups were comparable in electro impulse and drug therapy. Patients who received medical treatment were frequently admitted to hospitals for atrial fibrillation recurrence (p<0.001), compared with those who underwent electro impulse therapy. Adherence to antiarrhythmic therapy was low in the entire cohort of patients. There were no significant differences found between the clinical groups.Conclusion. Early diagnosis of the factors contributing to the progression of AF, the prescription of additional therapy for the secondary prevention of arrhythmia and the choice of its optimal treatment strategy may slow the progression of arrhythmia and the development of CHF, which will improve not only the clinical status of patients, but also their prognosis.Цель. Изучить особенности течения фибрилляции предсердий (ФП) у больных артериальной гипертонией (АГ) и экстракардиальной коморбидной патологией в зависимости от проводимой терапии, а также оценить приверженность к антиаритмической терапии.Материалы и методы. В обсервационном когортном исследовании наблюдалось 207 мужчин 45–65 лет с ФП (пароксизмальная и персистирующая форма) и АГ в сочетании с сахарным диабетом (СД) (n = 40), абдоминальным ожирением (АО) (n = 64) и хронической обструктивной болезнью легких (ХОБЛ) (n = 47). Группу сравнения составили 56 больных с ФП и АГ, без экстракардиальных заболеваний. В работе оценивались клинические, антропометрические показатели, тест для оценки приверженности Мориски-Грина, результаты инструментальной диагностики: электрокардиография (ЭКГ); холтеровское мониторирование электрокардиограммы (ХМ ЭКГ), суточное мониторирование артериального давления (СМАД) – системы суточного мониторирования SCHILLER (Шиллер, Швейцария), Эхокардиография – в М и 2D режимах на аппарате Vivid 7 (General Electric, USA). Все статистические расчёты проводили в программе Rstudio (version 0.99.879, RStudio, Inc., MA, USA).Результаты. Среди больных с ФП и АГ было выявлено 66% с сопутствующей экстракардиальной коморбидной патологией, из них с СД 20% больных; ХОБЛ выявлена у 22% пациентов, а АО отмечалось у 44% пациентов. По частоте электроимпульсной терапии (ЭИТ) и медикаментозной терапии (МТ) клинические группы были сопоставимы. Доказано, что пациенты, которым была проведена МТ, госпитализировались по поводу повторных приступов ФП достоверно чаще (р<0,001) по сравнению с группой пациентов, которым проводилась ЭИТ. Приверженность к антиаритмической терапии низкая у всей когорты обследованных, а при сравнительном анализе между клиническими группами не было выявлено достоверных различий.Заключение. Ранняя диагностика факторов прогрессирования ФП, назначение дополнительной терапии для вторичной профилактики аритмии и выбор правильной стратегии ее лечения могут замедлить прогрессирование аритмии и развитие хронической сердечной недостаточности, что улучшает не только клинический статус пациентов, но и их прогноз

    Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

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    Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization
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