Long-Wave Instability of Advective Flows in Inclined Layer with Solid Heat Conductive Boundaries

We investigate the stability of the steady convective flow in a plane tilted layer with ideal thermal conductivity of solid boundaries in the presence of uniform longitudinal temperature gradient. Analytically found the stability boundary with respect to the long-wave perturbations, find the critical Grashof number for the most dangerous among them of even spiral perturbation.Comment: in Russian, 18 pages, 5 figures, submited to Appl. mechanics and physics, RAS Siberian brunch, Novosibirsk, Russia; Key words: advective flow, oblique layer, a longitudinal temperature gradient, long-wave instabilit

Synthesis of Carboxymethyl Starch for increasing drilling mud quality in drilling oil and gas wells

This paper describes the impact of carboxymethyl starch preparation conditions on physicochemical properties of polysaccharide reagent, widely used as fluid loss reducing agent in drilling mud. Variation of the main parameters of carboxymethylation is researched in the experiment. The following conditions such as temperature and reaction time, amount of water, as well as ratio of NaOH to monochloracetic acid define the characteristics of carboxymethyl starch. The degree of substitution is defined for polysaccharides, as well as the characteristics of samples have been studied by infrared spectroscopy. Rheological characteristics and fluid loss indicator have been investigated to study the impact of the reagents on drilling mud quality

ВЫЯВЛЕНИЕ НЕБЛАГОПРИЯТНЫХ ФАКТОРОВ, СПОСОБСТВУЮЩИХ РАЗВИТИЮ МИОПИИ У СТУДЕНТОВ МЕДИЦИНСКИХ КОЛЛЕДЖЕЙ

To define the risk factors of myopia development among the students the authors got acquainted with spreading of the pathology among the students and their parents. 313 students of Tuimaizy medical college (at the age of 16 to 22 ys) and their parents (n = 579) participated in the study. Attention was paid to the internal factors (heredity, family atmosphere, quality of life) and to the external factors (the life, intensity in studying) -the factors promoting development of myopia. Special psychomedico-pedagogical commission has been organized for better health protection of the organ of vision in teenagers in Tuimaizy medical college.С целью определения факторов риска развития миопии среди студентов была изучена распространенность данного заболевания у студентов и их родителей. Проведено исследование студентов Туймазинского медицинского колледжа в возрасте от 16 до 22 лет, всего 313 человек, и их кровных родителей - 579 человек. В процессе исследования были выявлены следующие факторы: внутренние (наследственно-семейная среда, качество жизни) и внешние (образ жизни, интенсивность учебного процесса), способствующие возникновению или дальнейшему развитию миопии. Для укрепления здоровья органа зрения подростков на базе Туймазинского медицинского колледжа организована психолого-медико-педагогическая комиссия. Ведется комплексная работа, в которой участвуют психолог, преподаватели колледжа, фельдшер, офтальмолог, что обеспечивает массовую профилактику близорукости среди студентов

Başkortostan Cumhuriyeti Toratau Jeoparki bal arısı (apis mellifera) popülasyonunda tergit rengi değişimi

A phenetic analysis of the honey bee population of the Toratau Geopark (Russia) was performed. Over 1,000 worker and drone bee samples were collected from 250 colonies in 59 apiaries on the territory of the Toratau Geopark (Gafuriysky, Ishimbaysky, Meleuzovsky, and Sterlitamaksky districts of the Republic of Bashkortostan). Six phenes in worker bees and four phenes in drone bees were recognized. The phenes E, 1R, 2R, and 3R in workers and Is, I, and O-gray in drones were predominant in the honey bee population of the Toratau Geopark, which were associated with subspecies of the Clineage. These phenes can be used as indicators of introgressive hybridization in the local dark European honey bee population. The phenes allow for quick evaluation of certain honey bee colonies hybridization states.Toratau Jeoparkı'ndaki (Rusya) bal arısı popülasyonunun fenetik analizi yapılmıştır. Toratau Jeoparkı topraklarındaki (Başkurdistan Cumhuriyeti'nin Gafuriysky, Ishimbaysky, Meleuzovsky ve Sterlitamaksky bölgeleri) 59 arılıktaki 250 koloniden 1.000'den fazla işçi ve erkek arı örneği toplanmıştır. İşçi arılarda altı fen ve erkek arılarda dört tergit rengi tespit edilmiştir. İşçilerde E, 1R, 2R ve 3R ve erkek arılarda Is, I ve O-gri fenleri Toratau Jeoparkı'ndaki bal arısı popülasyonunda baskındı ve bunlar C soyunun alt türleriyle ilişkiliydi. Bu tergit rengi, yerel koyu Avrupa bal arısı popülasyonunda içsel melezleşmenin göstergeleri olarak kullanılabilir. Bu tergit renkleri, belirli bal arısı kolonilerinin melezleşme durumlarının hızlı bir şekilde değerlendirilmesine olanak sağlamaktadır.The article was prepared with supporting the grant of the head of the Republic of Bashkortostan Radiy Khabirov, grant title "Study of the Bashkir bee population on the territory of the Toratau Geopark

Extinction times in the subcritical stochastic SIS logistic epidemic

Many real epidemics of an infectious disease are not straightforwardly super- or sub-critical, and the understanding of epidemic models that exhibit such complexity has been identified as a priority for theoretical work. We provide insights into the near-critical regime by considering the stochastic SIS logistic epidemic, a well-known birth-and-death chain used to model the spread of an epidemic within a population of a given size $N$. We study the behaviour of the process as the population size $N$ tends to infinity. Our results cover the entire subcritical regime, including the "barely subcritical" regime, where the recovery rate exceeds the infection rate by an amount that tends to 0 as $N \to \infty$ but more slowly than $N^{-1/2}$. We derive precise asymptotics for the distribution of the extinction time and the total number of cases throughout the subcritical regime, give a detailed description of the course of the epidemic, and compare to numerical results for a range of parameter values. We hypothesise that features of the course of the epidemic will be seen in a wide class of other epidemic models, and we use real data to provide some tentative and preliminary support for this theory.Comment: Revised; 34 pages; 6 figure

Runoff variations in Lake Balkhash Basin, Central Asia, 1779-2015, inferred from tree rings

Long highly-resolved proxies for runoff are in high demand for hydrological forecasts and water management in arid Central Asia. An accurate (R2 = 0.53) reconstruction of October-September discharge of the Ili River in Kazakhstan, 1779–2015, is developed from moisture-sensitive tree rings of spruce sampled in the Tian Shan Mountains. The fivefold extension of the gauged discharge record represents the variability of runoff in the Lake Balkhash Basin for the last 235 years. The reconstruction shows a 40 year long interval of low discharge preceded a recent high peak in the first decade of the 2000s followed by a decline to more recent levels of discharge not seen since the start of the gauged record. Most reconstructed flow extremes (± 2σ) occur outside the instrumental record (1936–2015) and predate the start of large dam construction (1969). Decadal variability of the Ili discharge corresponds well with hydrological records of other Eurasian internal drainages modeled with tree rings. Spectral analysis identifies variance peaks (highest near 42 year) consistent with main hemispheric oscillations of the Eurasian climatic system. Seasonal comparison of the Ili discharge with sea-level-pressure and geopotential height data suggests periods of high flow likely result from the increased contribution of snow to runoff associated with the interaction of Arctic air circulation with the Siberian High-Pressure System and North Atlantic Oscillation

Cardiovascular events follow-up analysis in patients with sinus node dysfunction and implanted pacemaker

Dysfunction of sinus node (DSN) is the syndrome, characterized by symptoms of tissue hypoperfusion and manifestations on the electrocardiogram and could potentially lead to sudden death. The various impact of different types of pacemakers on life quality and cardiovascular endpoints was shown.Aim. To analyze follow-up cardiovascular endpoints in patients with DSN and installed pacemakers.Material and methods. Six hundred and ten patients with DSN were analyzed in follow-up period (39,7±0,8 months) for unfavorable cardiovascular events (myocardial infarction, strokes, cardiovascular and non-cardiovascular hospitalizations).Results. Mortality rate differed depending on DSN variant (p=0,041), and most unfavorable was “tachy-brady” and sinoatrial node arrest + sinus node block III types. Also, the difference in mortality rate was shown for pacing variants (p=0,049) with maximal rate number of deaths was in ventricular pacemakers (24,6%) less — in dual-chamber pacemakers (11,7%) and minimal — in atrial (5,5%). No changes in cardiovascular endpoints was found between groups with sinus and pacemaker’s rhythm (p>0,5).Conclusion. In the follow-up analyze the difference between cardiovascular endpoints in patients in various types of pacemakers and regimen of stimulation was shown