Radiation induced warping of protostellar accretion disks

We examine the consequences of radiatively driven warping of accretion disks surrounding pre-main-sequence stars. These disks are stable against warping if the luminosity arises from a steady accretion flow, but are unstable at late times when the intrinsic luminosity of the star overwhelms that provided by the disk. Warps can be excited for stars with luminosities of around 10 solar luminosities or greater, with larger and more severe warps in the more luminous systems. A twisted inner disk may lead to high extinction towards stars often viewed through their disks. After the disk at all radii becomes optically thin, the warp decays gradually on the local viscous timescale, which is likely to be long. We suggest that radiation induced warping may account for the origin of the warped dust disk seen in Beta Pictoris, if the star is only around 10-20 Myr old, and could lead to non-coplanar planetary systems around higher mass stars.Comment: 12 pages, including 3 figures. ApJ Letters, in pres

Исследование физических явлений в барботажной зоне плавильного агрегата «Победа» методом холодного моделирования Сообщение 3. Гидрогазодинамика комбинированной продувки жидкости газом с помощью донной и боковой фурм

Hydro-gas regularities of liquid combined blowing by gas were studied using cold modeling method at Archimedes criterion for lateral Arl = 12÷120 and bottom blowing Arb = 5÷60 simulating Pobeda bubbling unit. The blowing was performed simultaneously by bottom lance vertically fixed in centre of reactor and by the lateral lance which was attached at an angle 5° to the horizontal axis. The quantitative estimation of instantaneous and average circulation velocities (Vav) of liquid flow elements in different bath areas, depending on the location of blowing zone and Archimedes criterion, was performed. The liquid motion trajectory was determined. A vortex zone was revealed near the liquid surface and the reactor shell, where instantaneous velocity of the liquid flow elements changes from 69.9 to 181.1 mm/s and Vav = 123.8 mm/s. The circulation flows fade in the bulk of liquid and Vav decreases from 123.8 to 47.0 and 54.1 mm/s. It was shown that, in general, circulation velocity depends on the blowing intensity and appears to be higher for the zone of overlapping of lateral and bottom streams. The dynamic blowing conditions, which ensure the direct contact of lateral and bottom jets leading to their interflow and increased spatter formation, were identified. The characteristics of 3 types of surface oscillations for interface phases “pure liquid- gas-liquid layer”, as well as the estimation of the lateral and bottom blowing impact on the type of oscillation were provided. It has been noted that the introduction of the bottom blowing (Arb = 5) causes the wave-like motion of liquid (the 2nd type) along with the transverse oscillations of the 1st type, and at higher values of Arb = 25 the angular oscillations of the 3rd type develop. It has been shown that the presence of a lateral jet at the combined blowing decreases angles of bath swinging to 8–12° to horizontal axis. For the estimation of oscillation intensity, Δhl = (hl )max – (hl )min value, which means the difference between maximum (hl )max and minimum (hl )min height of liquid for the full-wave oscillations (τ), was introduced. The height of liquid (hl ) was plotted as a function of τ, Arl , Arb, Δhl was determined on the basis of obtained graph values, which varied upon modeling over the range of 7.7–69.5 mm. The relation between the liquid circulation velocity and the oscillation value (Δhl ) was established for different bath zones and dynamic conditions of the blowing. The impact of all oscillations types on potential erosive lining wear of Pobeda bubbling unit and the completeness of adoption of charging material nearby the bath surface was investigated.Методом холодного моделирования в интервалах величин критерия Архимеда для бокового (Arб = 12÷120) и донного (Arд = 5÷60) дутья применительно к условиям работы барботажного плавильного агрегата «Победа» (ПАП) исследованы гидрогазодинамические закономерности комбинированной продувки жидкости газом. Продувку осуществляли одновременно донной фурмой, установленной вертикально по центру реактора, и боковой, расположенной под углом 5° к горизонтальной оси. Проведена количественная оценка мгновенной и средней (Vср) скоростей циркуляции элементов потока жидкости на разных участках ванны в зависимости от местонахождения зоны продувки и критериев Архимеда. Определена траектория движения жидкости. Вблизи поверхности жидкости и корпуса реактора обнаружена вихревая зона, где мгновенная скорость движения элемента потока жидкости изменяется от 69,9 до 183,1 мм/с и Vср = 123,8 мм/с. В объеме жидкости циркуляционные потоки затухают, и Vср уменьшается от 123,8 до 47,0 и 54,1 мм/с. Показано, что в общем случае скорость циркуляции зависит от интенсивности продувки на фурмах и становится выше для области наложения боковой и донной струй. Определены динамические условия продувки, обеспечивающие непосредственный контакт бокового и донного факелов, приводящий к слиянию потоков и повышенному брызгообразованию. Приведена характеристика 3 видов колебаний поверхности раздела фаз «чистая жидкость – газожидкостный слой» и дана оценка влияния бокового и донного дутья на разновидность возникающих колебаний. Отмечено, что ввод донного дутья (Arд = 5) приводит, наряду с поперечными колебаниями 1-го типа, к появлению волнообразного движения жидкости (2-й тип), а при более высоких значениях Arд = 25 – к угловым колебаниям (3-й тип). Показано, что при комбинированной продувке наличие бокового факела уменьшает углы раскачивания ванны к горизонту до 8–12°. Для оценки интенсивности колебаний введена величина Δhж = (hж)max – (hж)min, т.е. разность между максимальной (hж)max и минимальной (hж)min высотой жидкости за полный цикл колебаний (τ). Построены зависимости высоты жидкости (hж) от τ, Arб и Arд, на основании которых определены величины Δhж, варьируемые при моделировании в интервале 7,7–69,5 мм. Для различных областей ванны и динамических условий продувки установлена взаимосвязь между скоростью циркуляции жидкости и величиной колебаний (Δhж). Рассмотрено влияние всех видов колебаний на возможный эрозивный износ футеровки ПАП и полноту усвоения шихтовых материалов вблизи поверхности ванны

A catalogue of dense cores and young stellar objects in the Lupus complex based on Herschel Gould Belt Survey observations

Context. How the diffuse medium of molecular clouds condenses in dense cores and how many of these cores will evolve in protostars is still a poorly understood step of the star formation process. Much progress is being made in this field, thanks to the extensive imaging of star-forming regions carried out with the Herschel Space Observatory. Aims. The Herschel Gould Belt Survey key project mapped the bulk of nearby star-forming molecular clouds in five far-infrared bands with the aim of compiling complete census of prestellar cores and young, embedded protostars. From the complete sample of prestellar cores, we aim at defining the core mass function and studying its relationship with the stellar initial mass function. Young stellar objects (YSOs) with a residual circumstellar envelope are also detected. Methods. In this paper, we present the catalogue of the dense cores and YSOs/protostars extracted from the Herschel maps of the Lupus I, III, and IV molecular clouds. The physical properties of the detected objects were derived by fitting their spectral energy distributions. Results. A total of 532 dense cores, out of which 103 are presumably prestellar in nature, and 38 YSOs/protostars have been detected in the three clouds. Almost all the prestellar cores are associated with filaments against only about one third of the unbound cores and YSOs/protostars. Prestellar core candidates are found even in filaments that are on average thermally subcritical and over a background column density lower than that measured in other star-forming regions so far. The core mass function of the prestellar cores peaks between 0.2 and 0.3 M⊙, and it is compatible with the log-normal shape found in other regions. Herschel data reveal several, previously undetected, protostars and new candidates of Class 0 and Class II with transitional disks. We estimate the evolutionary status of the YSOs/protostars using two independent indicators: the α index and the fitting of the spectral energy distribution from near- to far-infrared wavelengths. For 70% of the objects, the evolutionary stages derived with the two methods are in agreement. Conclusions. Lupus is confirmed to be a very low-mass star-forming region, in terms of both the prestellar condensations and the diffuse medium. Noticeably, in the Lupus clouds we have found star formation activity associated with interstellar medium at low column density, usually quiescent in other (more massive) star-forming regions

Исследование нарушений функциональных связей между сетью пассивного режима работы мозга и структурами мозжечка у пациентов с легкой черепно-мозговой травмой в острой стадии по данным фМРТ состояния покоя

Mild traumatic brain injury (mTBI) is the most common neurological damage in children that's why it is extremely important to identify and analyze biomarkers that can help in predicting patient's treatment and recovery in period of mTBI. Aim of this study is to verify a hypothesis that functional connectivity disturbances between intact cerebellum and DMN nodes are included in symptomatic manifestation of mTBI.Methods. 28 MR negative patients with mTBI were studied in age from 12 to 17 years (mean age – 14.7 years). The control group consisted of 23 healthy children. All MRI studies wereperformed on a Philips AchievadStream 3.0 T scanner equipped with a 32-channelPhilips dStream head coil. A 4 min rsfMRI gradient-echo echo planar imaging (EPI)sequence was acquired (TR = 3000 ms, echo time (TE) = 30 ms, 80 dynamics withdynamic scan time = 3 s). fMRI data were processed using functional connectivitytoolbox CONN.Results. No statistically significant differences in correlation strengths between control group and group of patients were detected as a result of DMN analysis. Intergroup seed-basedcorrelation ROI analysis revealed statistically significant (p < 0.05) differencein links between DMN regions and vermis (cerebellum): positive link in control group and negative link in groupof patients.Conclusions. The revealed changes in DMN neuronal connection and cerebellar regions in acute stage of mTBI patients can be an initial step of damages leading to cognitive deficit which can be developed in future.Легкая черепно-мозговая травма (лЧМТ) является наиболее распространенным неврологическим повреждением у детей, поэтому чрезвычайно важно идентифицировать и проанализировать биомаркеры, которые могут помочь в процессах лечения и выздоровления пациента с лЧМТ.Цель исследования: подтвердить гипотезу о том, что нарушения функциональных связей между неповрежденным мозжечком и узлами сети DMN включены в симптоматическое проявление лЧМТ.Методы. Обследованы 28 МР-негативных пациентов с лЧМТв возрасте от 12 до 17 лет (средний возраст 14,7 года). Контрольная группа состояла из 23 здоровых детей. Все МРТ-исследования проводились на сканере Philips Achieva dStream 3,0 Tл, оборудованном 32-канальной головной катушкой Philips dStream. Проведена фМРТ состояния покоя (EPI последовательность, TR = 3000 мс, время эха (TE) = 30 мс, 80 динамиков с динамическим временем сканирования 3 с). Данные фМРТ обработаны с использованием программного пакета CONN.Результаты. Не обнаружено статистически значимого различия в значениях коэффициентов функциональных связей между областями сети DMN в группах пациентов и контроля. Межгрупповой анализ выявил статистически значимое (р < 0,05) различие в нейронных связях между частями DMN и червем мозжечка (vermis, структурная часть мозжечка): положительная связь в контрольной группе и отрицательная связь в группе пациентов.Заключение. Выявленные изменения в нейрональных связях между областями DMN и мозжечка у пациентов с лЧМТ в остром периоде могут быть начальным этапом повреждений, приводящих к когнитивному дефициту, который может развиться в будущем

Роль магнитно-резонансной томографии при острой травме шейного отдела позвоночника у детей

Aim. To evaluate the role of magnetic resonance imaging (MRI) as a diagnostic method in children with acute trauma of the cervical spine and spinal cord, to compare the correspondence of MRI results with neurologic symptoms in accordance with the ASIA scale.Materials and methods. 156 children with acute trauma of spine and spinal cord at the age from 6 months up to 18 years were studied. MRI was performed on a Phillips Achieva 3T scanner. The standard protocol included MYUR (myelography) in coronal and sagittal projections, STIR and T2VI FS SE in sagittal projection, T2VI SE or T2 * VI FSGE (axial projection), 3D T1VI FSGE before and after contrast enhancement. Contrast substance was injected intravenously in the form of a bolus at the rate of 0.1 mmol/kg (equivalent to 0.1 ml/kg) at a rate of 3 to 4 ml.Results. The causes of cervical spine blunt trauma were: road accidents (55), catatrauma (60), “diver” trauma (21), blunt trauma (20). Intramedullary lesions of the spinal cord were detected: concussion (49), bruising / crushing (27), hematomia (34), disruption with divergence of segments (21), accompanied by edema (141); extramedullary lesions: epi- and subdural, intralesive and sub-connective and soft tissues hematomas (68), ruptures of bundles (48), fractures (108), dislocation and subluxation of the vertebrae (35), traumatic disc herniation (37), spinal cord compression and/or rootlets (63), statics violation (134), instability (156).Conclusion. MRI is the optimal method for spinal cord injury diagnostics. In the acute period of injury this technique has limited application, but it can however serve as a primary diagnostic method in these patients. MRI should be performed no later than the first 72 hours after injury. The most optimal for visualization of cervical spine trauma and spinal cord are T2VI SE and STIR in sagittal projection with suppression of signal from fat. MRI results correlate with neurologic symptoms at the time of performance according to the ASIA scale, and therefore MRI should be performed in all patients with acute cervical spine trauma, whenever possible.Цель исследования: оценить роль магнитно-резонансной томографии (МРТ) в качестве метода диагностики у детей с травмой шейного отдела позвоночника и спинного мозга, сравнить соответствие результатов МРТ с неврологическими симптомами и шкалой ASIA.Материал и методы. Исследовано 156 детей с острой травмой позвоночника и спинного мозга в возрасте от 6 мес до 18 лет. МРТ проводилась на томографе Phillips Achieva 3 Тл. Стандартный протокол исследования включал: миелографию (MYUR) в коронарной и сагиттальной проекциях, STIR и Т2ВИ FS SE в сагиттальной проекции, Т2ВИ SE или Т2ВИ FSGE (аксиальная проекция), 3D Т1ВИ FSGE до и после контрастного усиления. Контрастное вещество вводилось внутривенно в виде болюса из расчета 0,1 ммоль/кг (эквивалентно 0,1 мл/кг) со скоростью 3–4 мл.Результаты. Причинами тупой травмы шейного отдела позвоночника явились: дорожно-транспортные происшествия (55), кататравма (60), травма “ныряльщика” (21), тупая травма (20). Были выявлены интрамедуллярные повреждения спинного мозга: сотрясение (49), ушиб/размозжение (27), гематомиелия (34), разрыв с расхождением отрезков (21), сопровождавшиеся отеком (141); экстрамедуллярные повреждения: эпии субдуральные, внутри- и подсвязочные и гематомы мягких тканей (68), разрывы связок (48), переломы (108), вывих и подвывих позвонков (35), травматические грыжи диска (37), компрессия спинного мозга и/или корешков (63), нарушение статики (134), нестабильность (156).Заключение. МРТ – оптимальный метод диагностики позвоночно-спинномозговой травмы. В острый период травмы она имеет ограниченное применение, но однако может служить методом первичной диагностики у этих больных. МРТ желательно выполнять не позднее первых 72 ч после травмы. Наиболее оптимальными для визуализации травмы шейного отдела позвоночника и спинного мозга являются Т2ВИ SE и STIR в сагиттальной проекции с подавлением сигнала от жира. Результаты МРТ на момент выполнения коррелируют с неврологической симптоматикой в соответствии со шкалой ASIA, а поэтому МРТ следует проводить у всех пациентов с острой травмой шейного отдела позвоночника, когда это возможно

National scientific conference with international participation Biological rehabilitation of disturbed lands

The 10th national scientific conference with international participation Biological Rehabilitation of Disturbed Lands was held in the city of Yekaterinburg on September 4–7, 2017. More than 180 participants attended the conference from various institutions of 39 Russian cities of Russia and 7 countries (Azerbaijan, Armenia, Belarus, Kazakhstan, Morocco, Turkey, and Ukraine). Participation in the conference of a wide range of researchers and specialists is an indicator that the problem of rehabilitation is not becoming obsolete, but, on the contrary, it is growing more urgent. This problem is among the priority tasks of many regions of Russia and foreign countries in which oil and gas production, various mining industries are developed and the transformation of natural landscapes into post-industrial ones takes place. These problems are discussed at the conference, which takes place every 5 years in Yekaterinburg. Thanks to an active exchange of experience between specialists from different countries and due to analysis and discussion of the results, the prospects of cooperation aimed at improving the ecological situation and rational use of natural resources in the industrialized regions are developing. The publications of proceedings of the conference are of great scientific and practical value for scientists and specialists dealing with the problem of rehabilitation and monitoring of disturbed lands. Evaluating the global character of the problems of the conference, an appeal was addressed to the Governments of the regions of the Russian Federation for targeted financing of basic research in industrial regions with a high concentration of disturbed lands. To protect public health and preserve the gene pool of animals and plants, the need of assessing the quality of products obtained in the regions that undergo biological rehabilitation is emphasized. The published collection of conference proceedings presents the results of the research of the last decade

The preliminary diffusion tensor imaging study of cerebral microstructure in the acute phase of brain concussion

Purpose of the study. Concussion does not cause any lesions available for visualization using computed tomography and magnetic resonance imaging. However, it can cause changes at the microstructural level, which can be detected by the diffusion-tensor imaging. The purpose of this study is to identify the effect of acute concussion on diffusion parameters in the corpus callosum, corticospinal tract, and thalamus in children.Patients and methods. Fractional anisotropy and the apparent diffusion coefficient were determined in 11 patients with a diagnosis of concussion (41 ± 19 hours from the moment of injury) and in 11 healthy subjects. Philips Achieva dStream 3T magnetic resonance imager was used. Diffusion tensor imaging data were processed in the Philips Intellispace Portal program in the Fibertrack section.Results. Fractional diffusion anisotropy significantly increases and the apparent diffusion coefficient decreases in the thalamus of patients with concussion. In corpus callosum there is a growth trend in fractional anisotropy.Conclusion. The detected changes indicate the initial stage of cell edema in the thalamus caused by concussion. Diffusion-tensor imaging is the only magnetic resonance imaging method which may be sensitive to this pathology