GASTROINTESTINAL DISORDERS IN PATIENTS WITH ACUTE DISTURBANCE OF CEREBRAL BLOOD CIRCULATION

The authors performed parallel investigations between the nature of gastrointestinal complications and the nature and localization of vascular accidents in 40 patients hospitalized in the Division of Intensive Care of the Clinic of Neurology, Medical University, Varna, with a proved diagnosis of acute disturbance of cerebral blood circulation. The pathophysiological mechanisms leading to these complications were discussed. The data obtained were of practical value with a view to prevention and management of these complications in cases with acute cerebral circulatory disorders

UPON THE CLINICAL CHARACTERISTICS OF PERIODICAL HYPERSOMNIA

No abstrac

PECULIARITIES IN THE CLINICAL COURSE OF GUILLAIN-BARRE'S POLYRADICULONEURITIS

No abstrac

TREATMENT OF CHILDHOOD EPILEPSY WITH DEPAKINE

No abstrac

Marine diesel engines operating cycle simulation for diagnostics issues

The ongoing monitoring of marine diesel engines helps to detect the deviations of its parameters early and prevent major failures. But the experimental diagnostics data are generally limited, so frequently, it isn’t possible to get all the necessary information to make a clear decision. The mathematical simulation could be used to clarify the experimental data and to provide a deeper understanding of engine conditions. In this paper, the MAN 6L80MCE marine diesel engine of “Father S” bulk carrier diagnostics issues are considered. The diagnostics data were collected with DEPAS Handy equipment and present the information about indicated processes by every engine cylinder. The on-line resource Blitz-PRO was used for the simulation of the engine operation and helped to prove that the variation in exhaust valve’s closing timing is responsible for the observed compression pressure difference, while the irregularity in fuel injection causes the considerable difference in the maximum pressure

Методическое обеспечение для применения метода мажоритарного резервирования измерительных каналов

Introduction. For hazardous industries, the reliability of information and measuring equipment must ensure an almost complete absence of failure events, with their probability as low as 10-6. This requirement can be satisfied using various approaches, one of which is reservation. Reservation methods are classified into several types depending on such factors, as the operating mode of an object, failure types, frequency rate, etc. Majority redundancy schemes are rarely used in measuring equipment, particularly in measuring channels, largely because this method was initially aimed at improving the reliability of discrete digital devices. Thus far, no mathematical support for applying the method of majority reservation in measuring channels of analogue values has been developed. This gap determined the relevance of this study.Aim. To develop a methodological support for applying the method of majority reservation with the purpose of improving the level of measurement accuracy.Materials and methods. Both Russian and foreign sources published over the past 40 years on the topic of processing small samples when designing measuring channels for information and measuring systems were reviewed. The nonparametric Mann-Whitney rank test was applied to process small samples. Other research methods included mathematical modelling, as well as the mathematical apparatus of measurement theory andтsystems theory.Results. A measuring module with a redundant structure was simulated. Parametric and nonparametric rank criteria were considered. An algorithm allowing identification of the failure of a channel in a measuring module with a redundant structure was developed. The computational complexity of the developed algorithm is estimated by a polynomial of the second degree.Conclusion. The use of nonparametric rank criteria for processing small samples, as well as diagnostic situations for various combinations of these criteria, supports statistically grounded decision on the state of measuring channels. In the future, this method will be applied for diagnostic control of the serviceability of technological equipment used in fuel combustion, namely in boiler plants and installations for thermal waste destruction.Введение. Для опасных производств уровень надежности оборудования информационно- измерительных систем должен соответствовать требованию, что вероятность отказа является практически невозможным событием, т. е. равна приблизительно 106. Для реализации данного требования существуют различные способы повышения уровня надежности, одним из которых является резервирование. Оно делится на несколько видов в зависимости от влияющих факторов, таких, как режим работы объекта, типы отказов, кратность и т. п. Мажоритарное резервирование в измерительной технике, в частности в измерительных каналах, используется редко, так как данный метод был разработан для повышения надежности в дискретных цифровых устройствах. До настоящего времени соответствующее математическое обеспечение для применения мажоритарного резервирования измерительных каналов аналоговых величин отсутствовало. Вследствие этого возникла необходимость в его разработке.Цель работы. Разработка методического обеспечения для применения метода мажоритарного резервирования, позволяющего повысить достоверность результатов измерений.Материалы и методы. Проанализированы отечественные и зарубежные источники информации за последние 40 лет, связанные с обработкой малых выборок при проектировании измерительных каналов для информационно-измерительных систем. Применен непараметрический ранговый критерий Манна-Уитни для обработки малых выборок, использовалось математическое моделирование, математический аппарат теории измерений и теории систем.Результаты. Реализована модель измерительного модуля с избыточной структурой. Рассмотрены параметрические и непараметрические ранговые критерии. Разработан алгоритм, позволяющий выявитьотказ канала измерительного модуля с избыточной структурой. Вычислительная сложность алгоритма оценивается полиномом второй степени.Заключение. Рассмотренные возможности использования непараметрических ранговых критериев для работы с выборками малого объема, а также диагностические ситуации для различных комбинаций данных критериев позволяют принимать статистически обоснованное решение о состоянии измерительного канала. В перспективе планируется использовать данный метод при диагностическом контроле исправности оборудования технологических процессов, связанных с сжиганием топлива, а именно в котельных установках и установках термического уничтожения отходов

The impact of early massive mergers on the chemical evolution of Milky Way-like galaxies: insights from NIHAO-UHD simulations

Recent observations of the Milky Way (MW) found an unexpected steepening of the star-forming gas metallicity gradient around the time of the Gaia-Sausage-Enceladus (GSE) merger event. Here we investigate the influence of early ($t_{\mathrm{merger}}\lesssim5$ Gyr) massive ($M_{\mathrm{gas}}^{\mathrm{merger}}/M_{\mathrm{gas}}^{\mathrm{main}}(t_{\mathrm{merger}})\gtrsim10\%$) merger events such as the Gaia-Sausage Enceladus merger in the MW on the evolution of the cold gas metallicity gradient. We use the NIHAO-UHD suite of cosmological hydrodynamical simulations of MW-mass galaxies to study the frequency of massive early mergers and their detailed impact on the morphology and chemistry of the gaseous disks. We find a strong steepening of the metallicity gradient at early times for all four galaxies in our sample which is caused by a sudden increase in the cold gas disk size (up to a factor of 2) in combination with the supply of un-enriched gas ($\sim0.75$ dex lower compared to the main galaxy) by the merging dwarf galaxies. The mergers mostly affect the galaxy outskirts and lead to an increase in cold gas surface density of up to 200% outside of $\sim8$ kpc. The addition of un-enriched gas breaks the self-similar enrichment of the inter-stellar-medium and causes a dilution of the cold gas in the outskirts of the galaxies. The accreted stars and the ones formed later out of the accreted gas inhabit distinct tracks offset to lower [$\alpha$/Fe] and [Fe/H] values compared to the main galaxy's stars. We find that such mergers can contribute significantly to the formation of a second, low-$\alpha$ sequence as is observed in the MW.Comment: 13 pages, 10 figures, accepted by MNRA

Abundance trend with condensation temperature for stars with different Galactic birth places

During the past decade, several studies reported a correlation between chemical abundances of stars and condensation temperature (also known as Tc trend). However, the real astrophysical nature of this correlation is still debated. The main goal of this work is to explore the possible dependence of the Tc trend on stellar Galactocentric distances, Rmean. We used high-quality spectra of about 40 stars observed with the HARPS and UVES spectrographs to derive precise stellar parameters, chemical abundances, and stellar ages. A differential line-by-line analysis was applied to achieve the highest possible precision in the chemical abundances. We confirm previous results that [X/Fe] abundance ratios depend on stellar age and that for a given age, some elements also show a dependence on Rmean. When using the whole sample of stars, we observe a weak hint that the Tc trend depends on Rmean. The observed dependence is very complex and disappears when only stars with similar ages are considered. To conclude on the possible dependence of the Tc trend on the formation place of stars, a larger sample of stars with very similar atmospheric parameters and stellar ages observed at different Galactocentric distances is neededComment: Accepted by A&

Spiral-induced velocity and metallicity patterns in a cosmological zoom simulation of a Milky Way-sized galaxy

We use a high resolution cosmological zoom simulation of a Milky Way-sized halo to study the observable features in velocity and metallicity space associated with the dynamical influence of spiral arms. For the first time, we demonstrate that spiral arms, that form in a disc in a fully cosmological environment with realistic galaxy formation physics, drive large-scale systematic streaming motions. In particular, on the trailing edge of the spiral arms the peculiar galacto-centric radial and azimuthal velocity field is directed radially outward and azimuthally backward, whereas it is radially inward and azimuthally forward on the leading edge. Owing to the negative radial metallicity gradient, this systematic motion drives, at a given radius, an azimuthal variation in the residual metallicity that is characterised by a metal rich trailing edge and a metal poor leading edge. We show that these signatures are theoretically observable in external galaxies with Integral Field Unit instruments such as VLT/MUSE, and if detected, would provide evidence for large-scale systematic radial migration driven by spiral arms