Клапансохраняющие операции на аортальном клапане и восходящей аорте при радикальной коррекции врожденных и приобретенных пороков сердца. Непосредственные результаты

This paper presents the immediate outcomes of valve-sparing operations on the aortic valve and ascending aorta in radical correction of congenital and acquired heart disease. Materials and methods. The study enrolled 50 patients with aortic insufficiency who were operated upon at Shumakov National Medical Research Center of Transplantology and Artificial Organs from 2011 to 2019. The mean age was 48 ± 16 years, 64% of them were men (n = 32). The study included patients with tricuspid (n = 36, 72%) and bicuspid (n = 14, 28%) aortic valves. Aortic valve reimplantation was performed in 32 (64%) patients, aortic root remodeling - in 1 (2%). 17 (34%) patients had no aortic root reconstruction or remodeling. Aortic valve reimplantation was done in 4 (8%) cases in combination with coronary artery bypass grafting, and in 4 (8%) with mitral and tricuspid valve repair. Results. Thirty-day mortality was 0%. In 1 case (2%), a permanent pacemaker was installed due to complete atrioventricular block. There were no neurological and coronary events, and cases of endocarditis. In all patients (100%), aortic valve insufficiency after surgical correction did not exceed grade 1 according to echocardiographic follow-up examination. On aortic valve mean and peak gradients were 8 ± 6 and 15 ± 7 mm Hg, respectively. Findings. Type I and II valve-sparing reconstructive surgery (for bicuspid and tricuspid aortic valves) is an excellent alternative to prosthetic repair with great postoperative outcomes, low valve-associated complications and low mortality. В данной статье представлены непосредственные результаты клапансохраняющих операций на аортальном клапане и восходящей аорте при радикальной коррекции врожденных и приобретенных пороков сердца. Материалы и методы. В исследование вошли 50 пациентов с аортальной недостаточностью, оперированных в нашем центре с 2011-го по 2019 г. Средний возраст составил 48 ± 16 лет, 64% мужчины (n = 32). В исследование вошли пациенты с трехстворчатым (n = 36; 72%) и двустворчатым (n = 14; 28%) аортальным клапаном. Реимплантация аортального клапана выполнена у 32 (64%) пациентов, ремоделирование корня аорты - у 1 (2%). Без реконструкции и ремоделирования корня аорты - 17 (34%) пациентов. В сочетании с коронарным шунтированием - 4 (8%), с пластикой митрального и трикуспидального клапанов - 4 (8%). Результаты. Летальных случаев за период в 30 дней не наблюдали. В 1 случае (2%) в связи с полной атриовентрикулярной блокадой был установлен постоянный электрокардиостимулятор. Неврологических и коронарных событий, а также случаев возникновения эндокардита не наблюдали. У всех пациентов (100%) недостаточность на аортальном клапане после хирургической коррекции по данным эхокардиографического исследования не превышала 1-й степени. На аортальном клапане средний и пиковый градиент составили 8 ± 6 и 15 ± 7 мм рт. ст. соответственно. Выводы. Реконструктивная хирургия с сохранением нативных створок I и II типа, как двустворчатых, так и трехстворчатых аортальных клапанов является прекрасной альтернативой протезированию с отличными послеоперационными результатами, с низкими клапанассоциированными осложнениями и низкой смертностью

New model for system of mesoscopic Josephson contacts

Quantum fluctuations of the phases of the order parameter in 2D arrays of mesoscopic Josephson junctions and their effect on the destruction of superconductivity in the system are investigated by means of a quantum-cosine model that is free of the incorrect application of the phase operator. The proposed model employs trigonometric phase operators and makes it possible to study arrays of small superconducting granules, pores filled with superfluid helium, or Josephson junctions in which the average number of particles $n_0$ (effective bosons, He atoms, and so on) is small, and the standard approach employing the phase operator and the particle number operator as conjugate ones is inapplicable. There is a large difference in the phase diagrams between arrays of macroscopic and mesoscopic objects for $n_0 < 5$ and $U<J$ ($U$ is the characteristic interaction energy of the particle per granule and $J$ is the Josephson coupling constant). Reentrant superconductivity phenomena are discussed.Comment: 4 pages, 3 Postscript figure

Optimal Investment in the Development of Oil and Gas Field

Let an oil and gas field consists of clusters in each of which an investor can launch at most one project. During the implementation of a particular project, all characteristics are known, including annual production volumes, necessary investment volumes, and profit. The total amount of investments that the investor spends on developing the field during the entire planning period we know. It is required to determine which projects to implement in each cluster so that, within the total amount of investments, the profit for the entire planning period is maximum. The problem under consideration is NP-hard. However, it is solved by dynamic programming with pseudopolynomial time complexity. Nevertheless, in practice, there are additional constraints that do not allow solving the problem with acceptable accuracy at a reasonable time. Such restrictions, in particular, are annual production volumes. In this paper, we considered only the upper constraints that are dictated by the pipeline capacity. For the investment optimization problem with such additional restrictions, we obtain qualitative results, propose an approximate algorithm, and investigate its properties. Based on the results of a numerical experiment, we conclude that the developed algorithm builds a solution close (in terms of the objective function) to the optimal one

Performance of the Electromagnetic Calorimeter of the HERMES Experiment

The performance of the electromagnetic calorimeter of the HERMES experiment is described. The calorimeter consists of 840 radiation resistant F101 lead-glass counters. The response to positrons up to 27.5 GeV, the comparison between the measured energy and the momentum reconstructed from tracking, long-term stability, hadron rejection and neutral meson invariant mass reconstruction are shown.Comment: 22 pages, 13 figures, LaTeX, accepted by NI

Beam-helicity asymmetries for single-hadron production in semi-inclusive deep-inelastic scattering from unpolarized hydrogen and deuterium targets

A measurement of beam-helicity asymmetries for single-hadron production in deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV electrons and positrons off gaseous hydrogen and deuterium targets were collected by the HERMES experiment. The asymmetries are presented separately as a function of the Bjorken scaling variable, the hadron transverse momentum, and the fractional energy for charged pions and kaons as well as for protons and anti-protons. These asymmetries are also presented as a function of the three aforementioned kinematic variables simultaneously

Transverse-target-spin asymmetry in exclusive ω\omega-meson electroproduction

Hard exclusive electroproduction of $\omega$ mesons is studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. The amplitudes of five azimuthal modulations of the single-spin asymmetry of the cross section with respect to the transverse proton polarization are measured. They are determined in the entire kinematic region as well as for two bins in photon virtuality and momentum transfer to the nucleon. Also, a separation of asymmetry amplitudes into longitudinal and transverse components is done. These results are compared to a phenomenological model that includes the pion pole contribution. Within this model, the data favor a positive $\pi\omega$ transition form factor.Comment: DESY Report 15-14

Mechanism, dynamics, and biological existence of multistability in a large class of bursting neurons

Multistability, the coexistence of multiple attractors in a dynamical system, is explored in bursting nerve cells. A modeling study is performed to show that a large class of bursting systems, as defined by a shared topology when represented as dynamical systems, is inherently suited to support multistability. We derive the bifurcation structure and parametric trends leading to multistability in these systems. Evidence for the existence of multirhythmic behavior in neurons of the aquatic mollusc Aplysia californica that is consistent with our proposed mechanism is presented. Although these experimental results are preliminary, they indicate that single neurons may be capable of dynamically storing information for longer time scales than typically attributed to nonsynaptic mechanisms.Comment: 24 pages, 8 figure

Longitudinal double-spin asymmetries in semi-inclusive deep-inelastic scattering of electrons and positrons by protons and deuterons

A comprehensive collection of results on longitudinal double-spin asymmetries is presented for charged pions and kaons produced in semi-inclusive deep-inelastic scattering of electrons and positrons on the proton and deuteron, based on the full HERMES data set. The dependence of the asymmetries on hadron transverse momentum and azimuthal angle extends the sensitivity to the flavor structure of the nucleon beyond the distribution functions accessible in the collinear framework. No strong dependence on those variables is observed. In addition, the hadron charge-difference asymmetry is presented, which under certain model assumptions provides access to the helicity distributions of valence quarks

Методы восстановления генерального распределения душевых денежных доходов населения на основе выборочных данных большого объема

This paper provides an analysis of popular methods for correcting sample distribution of income per-capita and proposes a methodology for evaluating the parameters of a lognormal income distribution, taking into account unequal response rates between individuals with different income levels, income deciles - a result of survey design and the survey non-response rate. The authors propose the fitting of a lognormal distribution on the basis of comparing mean and boundary income levels for defined population intervals between the sample and general distribution, instead of the more common approach of frequency analysis between the two. The mean income value of a given interval, with enough observations, is less volatile than the individual frequencies on the interval. This is especially important in situations where individual frequencies in the sample distribution significantly differ from the population distribution itself. The authors examine two different criteria for estimating the optimal lognormal distribution parameters. The first method is similar to the methodology used in Russian statistics, and does not require preliminary information on the share of the poor population. The parameters are estimated using the condition of equality between the sample and population mean income, and the right-income boundary of the first income deciles. The second criterion is based on minimizing the squared sum of deviations between the mean income levels for the middle eight income deciles of the sample and population mean values. Neither of the two criteria uses the hypothesis of non-response rates increasing with households’ income growth, which allows one to assess the representative-value of the sample survey. The results of the calculations show that the method achieves the highest parity between sample and population distributions in the middle-part of the lognormal distribution, but suffers from underrepresentation in the lower part of the distribution, i.e. for poor households and individuals.В статье дается анализ популярных методов коррекции выборочного распределения душевых доходов населения и описывается методика оценки параметров логнормального распределения денежных доходов, учитывающая неравномерное представительство респондентов с разным уровнем доходов, в доходных децилях, которое зависит от дизайна выборки и доли отказов респондентов от участия в опросе. Ключевая идея работы состоит в выборе критерия для оценки параметров теоретического распределения, основанного не на сравнении групповых частот, а на сравнении границ и средних значений в теоретических децилях выборочных и искомых распределений. Средние значения в интервалах доходов, при достаточном количестве наблюдений, значительно меньше зависят от частоты представительности респондентов в интервалах. Это особенно важно, когда частотные характеристики выборки существенно отличаются от аналогичных показателей генеральной совокупности. Рассмотрены два критерия оптимального выбора параметров логнормального распределения. Первый близок по методике, используемой в российской статистике, но при этом не требуется предварительная информация о том, какую часть составляет бедное население. Параметры оцениваются исходя из условия выполнения равенства среднего генерального дохода и совпадения выборочных и теоретических границ первого децильного интервала. Во втором случае минимизируется сумма отклонений выборочных и теоретических средних, рассчитанных в теоретических децилях. Оба критерия построены без учета гипотезы о возрастании вероятности отказов населения от участия в опросе в связи с ростом дохода домохозяйства, что позволяет сделать оценки представительности генеральных данных в выборочной совокупности. Результаты конкретных расчетов показывают наибольшее представительство в средней части распределения и недостаточность наблюдений на концах, то есть и в группе бедных домохозяйств