Self-field effects upon the critical current density of flat superconducting strips

We develop a general theory to account self-consistently for self-field effects upon the average transport critical current density Jc of a flat type-II superconducting strip in the mixed state when the bulk pinning is characterized by a field-dependent depinning critical current density Jp(B), where B is the local magnetic flux density. We first consider the possibility of both bulk and edge-pinning contributions but conclude that bulk pinning dominates over geometrical edge-barrier effects in state-of-the-art YBCO films and prototype second-generation coated conductors. We apply our theory using the Kim model, JpK(B) = JpK(0)/(1+|B|/B0), as an example. We calculate Jc(Ba) as a function of a perpendicular applied magnetic induction Ba and show how Jc(Ba) is related to JpK(B). We find that Jc(Ba) is very nearly equal to JpK(Ba) when Ba > Ba*, where Ba* is the value of Ba that makes the net flux density zero at the strip's edge. However, Jc(Ba) is suppressed relative to JpK(Ba) at low fields when Ba < Ba*, with the largest suppression occurring when Ba*/B0 is of order unity or larger.Comment: 9 pages, 4 figures, minor revisions to add four reference

Magnetic-field and current-density distributions in thin-film superconducting rings and disks

We show how to calculate the magnetic-field and sheet-current distributions for a thin-film superconducting annular ring (inner radius a, outer radius b, and thickness d<<a) when either the penetration depth obeys lambda < d/2 or, if lambda > d/2, the two-dimensional screening length obeys Lambda = 2 lambda^2/d << a for the following cases: (a) magnetic flux trapped in the hole in the absence of an applied magnetic field, (b) zero magnetic flux in the hole when the ring is subjected to an applied magnetic field, and (c) focusing of magnetic flux into the hole when a magnetic field is applied but no net current flows around the ring. We use a similar method to calculate the magnetic-field and sheet-current distributions and magnetization loops for a thin, bulk-pinning-free superconducting disk (radius b) containing a dome of magnetic flux of radius a when flux entry is impeded by a geometrical barrier.Comment: 10 pages, 13 figure

Development of a management tool to prevent emotional burnout in project teams

The article studies the phenomenon of emotional burnout in the framework of project team management. The authors of the article have considered the concept of emotional burnout, identified the causes of stress among project team members during project implementation and concluded that probability of emotional burnout syndrome can be reduced due to effective selection of project team by manager and balanced distribution of responsibilities among team members. As a solution for project managers, the authors have considered a “functional map” tool. A comparison of the functional map and a job description has been made in order to visualize distinctive features of the functional map. Based on the tool’s advantages and disadvantages analysis, the authors have proposed innovations to minimize probability of burnout syndrome among project team members. In conclusion, the authors have given their recommendations to project managers on controlling emotional burnout in project teams

Field-Dependent Critical Current in Type-II Superconducting Strips: Combined Effect of Bulk Pinning and Geometrical Edge Barrier

Recent theoretical and experimental research on low-bulk-pinning superconducting strips has revealed striking dome-like magnetic-field distributions due to geometrical edge barriers. The observed magnetic-flux profiles differ strongly from those in strips in which bulk pinning is dominant. In this paper we theoretically describe the current and field distributions of a superconducting strip under the combined influence of both a geometrical edge barrier and bulk pinning at the strip's critical current Ic, where a longitudinal voltage first appears. We calculate Ic and find its dependence upon a perpendicular applied magnetic field Ha. The behavior is governed by a parameter p, defined as the ratio of the bulk-pinning critical current Ip to the geometrical-barrier critical current Is0. We find that when p > 2/pi and Ip is field-independent, Ic vs Ha exhibits a plateau for small Ha, followed by the dependence Ic-Ip ~ 1/Ha in higher magnetic fields.Comment: 4 pages, 2 figures, Fig. 1 revised, submitted to Phys. Rev.

Magnetic-field dependence of the critical currents in a periodic coplanar array of narrow superconducting strip

We calculate the magnetic-field dependence of the critical current due to both geometrical edge barriers and bulk pinning in a periodic coplanar array of narrow superconducting strips. We find that in zero or low applied magnetic fields the critical current can be considerably enhanced by the edge barriers, but in modest applied magnetic fields the critical current reduces to that due to bulk pinning alone.Comment: 23 pages, 7 figure

Generation of a localised microwave magnetic field by coherent phonons in a ferromagnetic grating

A high-amplitude microwave magnetic field localized at the nanoscale is a desirable tool for various applications within the rapidly developing field of nanomagnetism. Here, we drive magnetization precession by coherent phonons in a metal ferromagnetic nanograting and generate ac-magnetic induction with extremely high amplitude (up to 10 mT) and nanometer scale localization in the grating grooves. We trigger the magnetization by a laser pulse which excites localized surface acoustic waves. The developed technique has prospective uses in several areas of research and technology, including spatially resolved access to spin states for quantum technologies

РЕСПИРАТОРНЫЕ НАРУШЕНИЯ В ОСТРОМ ПЕРИОДЕ ОСЛОЖНЕННОЙ ТРАВМЫ ШЕЙНОГО ОТДЕЛА ПОЗВОНОЧНИКА

Objective. Evaluating the results of respiratory therapy in patients with complicated traumatic injury of the cervical spine.Materials and methods. A retrospective comparative analysis of the clinical course was carried out in 52 patients with complicated traumatic injury of the cervical spine: group A: complete spinal cord injury (ASIA A), 37 patients and group B: incomplete injury (ASIA B), 15 patients. The severity of patients' status on integral scales, parameters of the respiratory pattern and thoracopulmonary compliance, gas composition, and acidbase status of the blood were assessed. Data on patients who required prolonged mechanical ventilation, duration of mechanical ventilation, incidence of nosocomial pneumonia, duration of stay in the ICU, time of hospital treatment, and mortality were included in the analysis. Results. The average APACHE II and SOFA scores were higher in group A patients. The development of the acute respiratory failure required longterm mechanical ventilation (more than 48 hours) in 91.4% of group A patients and in 53.3% of group B patients. Ventilatorassociated pneumonia complicated the disease in 81.3% of group A patients and 62.5% of group B patients and was accompanied by sepsis in 25% and 12.5% of cases, respectively. Statistically significant deterioration of biomechanical properties and gas exchange function of the lungs was observed in patients complicated with septic pneumonia.Conclusion. Patients with complicated ASIA A and ASIA B cervical spine injuries demonstrate the presence of respiratory failure of neurogenic origin. In addition, the infectious bronchopulmonary complications aggravated respiratory failure in patients with ASIA A injury in 70.3% versus 33.3% in patients with ASIA B. Developmentof pulmonogenic sepsis led to deterioration of the biomechanical and gas exchange functions of the lungs and increased the likelihood of unfavorable outcome of the disease in 77.8% of cases. The high incidence of respiratory disorders in patients with complicated cervical spine injury requires timely decision on ventilatory support, especially in patients with complete spinal cord injury.Цель исследования: определить частоту развития и характер респираторных нарушений у больных с осложненной травмой шейного отдела позвоночника в зависимости от исходного неврологического дефицита.Материалы и методы. Проведен ретроспективный сравнительный анализ течения заболевания у 52 пациентов с осложненной травмой шейного отдела позвоночника: группа A — полное повреждение спинного мозга (ASIA А) — 37 больных; группа В — неполное повреждение (ASIA В) — 15 больных. Оценивали тяжесть состояния пациентов по интегральным шкалам, показатели респираторного паттерна и торакопульмональной податливости, газовый состав и кислотноосновное состояние крови. Регистрировали количество больных, нуждавшихся в пролонгированной ИВЛ, длительность ИВЛ, частоту развития нозокомиальной пневмонии, длительность пребывания в ОРИТ, сроки стационарного лечения, летальность.Результаты. Средний балл по шкалам APACHE II и SOFA у больных в группе А имел более высокий уровень. Развитие острой дыхательной недостаточности требовало проведения длительной ИВЛ (более 48 ч) в группе А у 91,4% больных, а в группе В у 53,3% больных. Вентиляторассоциированная пневмония осложнила течение заболевания у 81,3% больных группы А и у 62,5% группы В с развитием сепсиса в 25% и в 12,5% случаях соответственно. Статистически значимое ухудшение биомеханических свойств и газообменной функции легких выявлено у больных, осложненных септической пневмонией.Заключение. Осложненная травма шейного отдела позвоночника типа ASIA A и ASIA B определяет на личие дыхательной недостаточности нейрогенного генеза. Присоединение инфекционных бронхолегочных осложнений усугубляет течение дыхательной недостаточности у пациентов с ASIA A в 70,3%, с ASIA В в 33,3% случаев. Развитие пульмоногенного сепсиса приводит к ухудшению биомеханических и газообменной функций легких и увеличивает вероятность неблагоприятного исхода заболевания в 77,8% случаев. Высокая частота респираторных нарушений у пациентов с осложненной травмой шейного отдела позвоночника требует своевременного принятия решения о необходимости респираторной поддержки, особенно у пациентов с полным повреждением спинного мозга

Respiratory Disorders in Complicated Cervical Spine Injury

Objective. Evaluating the results of respiratory therapy in patients with complicated traumatic injury of the cervical spine.Materials and methods. A retrospective comparative analysis of the clinical course was carried out in 52 patients with complicated traumatic injury of the cervical spine: group A: complete spinal cord injury (ASIA A), 37 patients and group B: incomplete injury (ASIA B), 15 patients. The severity of patients' status on integral scales, parameters of the respiratory pattern and thoracopulmonary compliance, gas composition, and acidbase status of the blood were assessed. Data on patients who required prolonged mechanical ventilation, duration of mechanical ventilation, incidence of nosocomial pneumonia, duration of stay in the ICU, time of hospital treatment, and mortality were included in the analysis. Results. The average APACHE II and SOFA scores were higher in group A patients. The development of the acute respiratory failure required longterm mechanical ventilation (more than 48 hours) in 91.4% of group A patients and in 53.3% of group B patients. Ventilatorassociated pneumonia complicated the disease in 81.3% of group A patients and 62.5% of group B patients and was accompanied by sepsis in 25% and 12.5% of cases, respectively. Statistically significant deterioration of biomechanical properties and gas exchange function of the lungs was observed in patients complicated with septic pneumonia.Conclusion. Patients with complicated ASIA A and ASIA B cervical spine injuries demonstrate the presence of respiratory failure of neurogenic origin. In addition, the infectious bronchopulmonary complications aggravated respiratory failure in patients with ASIA A injury in 70.3% versus 33.3% in patients with ASIA B. Developmentof pulmonogenic sepsis led to deterioration of the biomechanical and gas exchange functions of the lungs and increased the likelihood of unfavorable outcome of the disease in 77.8% of cases. The high incidence of respiratory disorders in patients with complicated cervical spine injury requires timely decision on ventilatory support, especially in patients with complete spinal cord injury