On a determination of the boundary function in the initial-boundary value problem for the second order hyperbolic equation

In the paper the problem of determination of the boundary function is studied in the initial boundary value problem described by the second order hyperbolic equation. With the help of the additional condition, the functional is constructed, and the problem under consideration is reduced to the optimal control problem. The differential of the function is calculated, a necessary and sufficient condition for optimality is proved. Pages of the article in the issue: 56 - 60 Language of the article: Englis

Can Hall drag be observed in Coulomb coupled quantum wells in a magnetic field?

We study the transresistivity \tensor\rho_{21} (or equivalently, the drag rate) of two Coulomb-coupled quantum wells in the presence of a perpendicular magnetic field, using semi-classical transport theory. Elementary arguments seem to preclude any possibility of observation of ``Hall drag'' (i.e., a non-zero off-diagonal component in \tensor\rho_{21}). We show that these arguments are specious, and in fact Hall drag can be observed at sufficiently high temperatures when the {\sl intra}layer transport time $\tau$ has significant energy-dependence around the Fermi energy $\varepsilon_F$. The ratio of the Hall to longitudinal transresistivities goes as $T^2 B s$, where $T$ is the temperature, $B$ is the magnetic field, and $s = [\partial\tau/ \partial\varepsilon] (\varepsilon_F)$.Comment: LaTeX, 13 pages, 2 figures (to be published in Physica Scripta, Proc. of the 17th Nordic Semiconductor Conference

rac-Ethyl 6-hy­droxy-6-methyl-3-oxo-4-phenyl-1,3,4,5,6,7-hexa­hydro­benzo[c][1,2]oxazole-5-carboxyl­ate

In the title compound, C17H19NO5, the cyclo­hexene ring is in a half-chair conformation and the isoxazole ring in an envelope conformation with the N atom as the flap. The C atoms in the 4- and 6-positions are of the same absolute configuration, whereas the C atom in the 5-position is of the opposite configuration, i.e. (4S*,5R*,6S*). The methyl fragment of the eth­oxy­carbonyl group at position 5 is disordered over two sets of sites in a 0.60:0.40 ratio. The crystal packing displays inter­molecular N—H⋯O and O—H⋯O hydrogen bonds

rac-5-Acetyl-6-hy­droxy-3,6-dimethyl-4-phenyl-2H-4,5,6,7-tetra­hydro­indazol-1-ium chloride

The structure of the title compound, C17H21N2O2 +·Cl−, is of inter­est with respect to its biological activity. The title compound comprises an organic cation and a chloride anion in the asymmetric unit. The positive charge is localized in a pyrazole moiety forming a pyrazolium cation. The structure displays inter­molecular O—H⋯Cl and N—H⋯Cl hydrogen bonding

Negative magneto-resistance of electron gas in a quantum well with parabolic potential

We have studied the electrical conductivity of the electron gas in parallel electric and magnetic fields directed along the plane of a parabolic quantum well (across the profile of the potential). We found a general expression for the electrical conductivity applicable for any magnitudes of the magnetic field and the degree of degeneration of the electron gas. A new mechanism of generation of the negative magnetoresistance has been revealed. It has been shown that in a parabolic quantum well with a non-degenerated electron gas the negative magnetoresistance results from spin splitting of the levels of the size quantization.Comment: 15 pages, 3 figure

A comparative evaluation of the energy consumption parameters of a gasoline generator set with constant and variable rotational speed

The paper presents a comparative mathematical study of the energy parameters of two gasoline generator sets with constant and variable rotational speed. Issues include the advantages of using a generator set with variable speed.В работе приведен сравнительный расчетный анализ энергетических показателей бензо-генераторных установок с постоянной и переменной частотами вращения. Сделаны выводы относительно преимуществ применения установки с переменной частотой вращения

Pain development and analgesia in athletes with ankle joints and ligaments injury

The pain feeling in athletes results from nociceptive and antinociceptive systems activity. Mostly pain follows injuries. Ankle joints and ligaments injury is one of the most often trauma. Pain intensity directly depends on the number of injured structures and the degree of the injury. Besides that pain intensity depends upon various factors such as gender and age. The history of injuries can increase the risk of repeated injuries and pain may become chronic. Psycho-emotional experiences during the competition can lead to pain without physical injuries. Anesthesia is important aspect in athletes’ life and it must be effective. Not all currently available medication are approved by the World Anti-Doping Agency. Every year “WADA Prohibited List” is reviewed and every athlete must follow it. The permitted and most effective methods of pain relief for joints and ligaments injury are cooling aerosols, non-steroidal anti-infl ammatory drugs and kinesio taping. Each of these methods has its own characteristics

Випадок успішного консервативного лікування шлункової нориці як одного з багатьох ускладнень виразкової хвороби дванадцятипалої кишки

The publication is based on the clinical examination of the patient M. during last six years. In 2010 46 years old patient was sent to the Center of acute pancreatitis with the diagnosis of severe acute pancreatitis. The patient was operated after 12 hours of the admission on the perforated duodenal ulcer with widespread peritonitis against the background of ulcerative stenosis of the duodenum. Suturing ulcers with superposition of anterior gastroenteroanastomosis was perfomed. Systematic treatment was not recieved. In February 2016, he entered the surgical department with a phlegmon of the anterior abdominal wall, the case of which was the penetrarion of ulcers of gastroenteroanastomosis into the anterior abdominal wall. By opening the phlegmon a gastric fistula was opened, which was closed against a background of intensive anti-inflammatory therapy and the use of large doses of pentacrasole.In April 2016 the operation of resection of the stomac and Roux gastroenteroanastomosis were perfomed. Later the patient suffered three episodes of bleeding, they were stoped conservatively.At the end of 2016 there were difficulties in swallowing food, stenosis in the oesophagus was diagnosed. It was treated in the thoracic department using bouginage and permeability was restored. Inspection in April 2017 – the patient has satisfactory condition, swallow­ing is free. At the FGD in the field of gastroenteroanastomosis recurrent u lcer was found.The patient was offered hospital treatment in the department of gastroenterology and the examination for Zollinger-Ellison syndrome.В публикации приведено клиническое наблюдение одного пациента М. в течение последних шести лет. В 2010 г. пациент М., 46 лет был направлен в центр острого панкреатита с предположительным диагнозом острый тяжелый панкреатит, а через 12 ч после поступлення прооперирован по поводу перфоративной язвы двенадцатиперстной кишки с распространенным перитонитом на фоне язвенного стеноза двенадцатиперстной кишки. Выполнено ушивание язвы с наложением впереди- ободочного гастроэнтероанастомоза. Систематического лечения не получал. В феврале 2016 г. поступил в хирургическое отделение с флегмоной передней брюшной стенки, причиной которой была пенетрация язвы гастроэнтероанастомоза в переднюю брюшную стенку. После вскрытия флегмоны открылся желудочный свищ, который закрылся на фоне интенсивной противовоспалительной терапии и применением больших доз пантапразола.В апреле месяце 2016 г. проведена резекция желудка и гастроэнтероанастомоз по Ру. В последующем перенес три эпизода кровотечений, которые купировали консервативно.В конце 2016 г. появились затруднения при глотании пищи, диагностирован стеноз нижней части пищевода, лечился в торакальном отделении посредством бужированиия, проходимость восстановлена. Повторно осмотрен в апреле 2017 г., состояние удовлетворительное, глотание свободное. На ФГДС в области гастроэнтероанастомоза рецидивная язва.Больному предложено стационарное лечение в отделении гастроэнтерологии и обследование на предмет синдрома Золлингера– Эллисона.У публікації наведено клінічне спостереження одного пацієнта М. протягом останніх шести років. У 2010 р. пацієнт М., 46 років був направлений в центр гострого панкреатиту з підозрою на гострий тяжкий панкреатит, а через 12 год після госпіталізації прооперований з приводу перфоративної виразки дванадцатипалої кишки з поширеним перитонітом на тлі ви­разкового стенозу дванадцатипалої кишки. Виконано ушивання виразки з накладанням попереду-ободового гастроентероанастомозу. Систематичного лікування не отримував. У лютому 2016 р. госпіталізований в хірургічне відділення з флегмоною передньої черевної стінки, причиною якої була пенетрація виразки гастроентероанастомозу в передню черевну стінку. Після розкриття флегмони відкрилася шлункова нориця, яка закрилася на тлі інтенсивної протизапальної терапії і приймання мак­симальних доз пантапразолу.У квітні 2016 р. виконано резекцію шлунка і гастроентероанастомоз за Ру. В подальшому було три епізоди кровотеч, які усували консервативно.У кінці 2016 р. з'явилися труднощі при ковтанні їжі, діагностовано стеноз нижньої третини стравоходу, пройшов курс лікування в торакальному відділенні за допомогою бужування, прохідність відновлена. Повторно оглянутий в квітні 2017 р., стан задовільний, ковтання вільне. На ФГДС у ділянці гастроентероанастомозу рецидивна виразка.Хворому запропоновано стаціонарне лікування у відділенні гастроентерології та обстеження з підозрою на синдром Золлінгера–Еллісона

Diameter-dependent thermopower of Bi nanowires

We present a study of electronic transport in individual Bi nanowires of large diameter relative to the Fermi wavelength. Measurements of the resistance and thermopower of intrinsic and Sn-doped Bi wires with various wire diameters, ranging from 150-480 nm, have been carried out over a wide range of temperatures (4-300 K) and magnetic fields (0-14 T). We find that the thermopower of intrinsic Bi wires in this diameter range is positive (type-p) below about 150 K, displaying a peak at around 40 K. In comparison, intrinsic bulk Bi is type-n. Magneto-thermopower effects due to the decrease of surface scattering when the cyclotron diameter is less than the wire diameter are demonstrated. The measurements are interpreted in terms of a model of diffusive thermopower, where the mobility limitations posed by hole-boundary scattering are much less severe than those due to electron-hole scattering.Comment: 32 pages, 12 figures. Previous version replaced to improve readabilit