Model for self-consistent analysis of arbitrary MQW structures

Self-consistent computations of the potential profile in complex semiconductor heterostructures can be successfully applied for comprehensive simulation of the gain and the absorption spectra, for the analysis of the capture, escape, tunneling, recombination, and relaxation phenomena and as a consequence it can be used for studying dynamical behavior of semiconductor lasers and amplifiers. However, many authors use non-entirely correct ways for the application of the method. In this paper the versatile model is proposed for the investigation, optimization, and the control of parameters of the semiconductor lasers and optical amplifiers which may be employed for the creation of new generations of the high-density photonic systems for the information processing and data transfer, follower and security arrangements. The model is based on the coupled Schredinger, Poisson and drift-diffusion equations which allow to determine energy quantization levels and wave functions of charge carriers, take into account built-in fields, and to investigate doped MQW structures and those under external electric fields influence. In the paper the methodology of computer realization based on our model is described. Boundary conditions for each equation and consideration of the convergence for the method are included. Frequently encountered in practice approaches and errors of self-consistent computations are described. Domains of applicability of the main approaches are estimated. Application examples of the method are given. Some of regularities of the results which were discovered by using self-consistent method are discussed. Design recommendations for structure optimization in respect to managing some parameters of AMQW structures are given.Comment: 12 pages, 2 table, 4 figures, Optics East Symposium, Conference on Physics and Applications of Optoelectronic Devices, October 25-28, 2004, Philadelphia, Pennsylvania, US

Effect of double layers on magnetosphere-ionosphere coupling

The Earth's auroral zone contains dynamic processes occurring on scales from the length of an auroral zone field line which characterizes Alfven wave propagation to the scale of microscopic processes which occur over a few Debye lengths. These processes interact in a time-dependent fashion since the current carried by the Alfven waves can excite microscopic turbulence which can in turn provide dissipation of the Alfven wave energy. This review will first describe the dynamic aspects of auroral current structures with emphasis on consequences for models of microscopic turbulence. A number of models of microscopic turbulence will be introduced into a large-scale model of Alfven wave propagation to determine the effect of various models on the overall structure of auroral currents. In particular, the effects of a double layer electric field which scales with the plasma temperature and Debye length is compared with the effect of anomalous resistivity due to electrostatic ion cyclotron turbulence in which the electric field scales with the magnetic field strength. It is found that the double layer model is less diffusive than in the resistive model leading to the possibility of narrow, intense current structures

Dynamics of magnetosphere-ionosphere coupling including turbulent transport

A two dimensional two-fluid MHD model including anomalous resistivity was used to investigate the dynamics of magnetosphere-ionosphere coupling. When a field-aligned current is generated on auroral field lines, the disturbance propagates towards the ionosphere in the form of a kinetic Alfven wave. When the current exceeds a critical value, microscopic turbulence is produced, which modifies the propagation of the Alfven wave. This process is modeled by a nonlinear collision frequency, which increases with the excess of the drift velocity over the critical value. Turbulence leads to absorption and reflection of the Alfven wave, partially decoupling the generator from the ionosphere. The approach to a steady-state is strongly dependent on the presence or absence of the turbulence. The current is self-limiting, since a current in excess of critical causes a diffusion of the magnetic field perturbation and a reduction of current

Double and joint degree programs in Ukraine: realia and prospects

During the last ten years, with the adoption of legislation to promote academic mobility in Ukraine, the interest towards double/joint degree programs has increased dramatically. However, very little empirical research has been carried out to analyse the spread of the programs across Ukrainian universities and to outline the way such programs are used in particular educational institutions. The aim of this study was, therefore, to investigate the level of development of double/joint degree programs in Ukraine, analyse these programs according to the field of study and academic level. The main issues addressed in this article are special aspects, opportunities and issues connected with double and joint degrees. It is apparent that most double degree programs are offered in the areas of economics and management, while there are much fewer programs in the area of business. Double degree programs in economics, management and business tend to be fewer in number than non-degree mobility programs. The most common partner countries for establishing double degree programs are Poland, France, Italy, Slovakia, Sweden, the Netherlands, Austria, Spain and Lithuania. Sustainability of each program can be reached by permanent work on its improvement which includes making clear requirements, promotion of a program, increasing awareness on the benefits of studying abroad

Theoretical preparation as an important component of the system compulsory physical education process

We consider the value of theoretical knowledge in the field of physical culture as a tool to enhance the cognitive activity of students of the 8t class and their relationship to the concerned relevant knowledge in this discipline. The study used data from test of students (80 people). It is proved that a certain number of students possess a high level of theoretical knowledge, but in general this is not enough in today's reality to teach them how to apply the relevant knowledge into practice

Порівняльна характеристика волинського та карпатського генотипів Potentilla erecta (L.) raeusch (Rosaceae) в культурі

The results of cultivation of Potentilla erecta (L.) Raeusch of Carpatian and Volynian origin have been analyzed with the purpose to determine differences in the terms of passing through phenological phases of seasonal development, growth and seed productivity.Проаналізовано результати культивування Potentilla erecta (L.) Raeusch карпатського та волинського походження з метою виявлення відмінностей між ними в термінах проходження фенологічних фаз сезонного розвитку, росту і насіннєвої продуктивності

Two-step synthesis of polymer fibre material comprising indium-, bismuth-, or antimony-doped nanosized tin oxides

In this paper, we present a method of formation of polymer fibre materials comprising dispersed oxides of rare and trace elements. The results of X-ray diffraction and spectral analyses show that the optimum synthesis conditions of the antimony-doped tin oxide, indium-doped tin oxide, and bismuth-doped tin oxide particles are provided using the "reverse" hydrolytic co-precipitation of hydroxides from chloride solutions combined with the subsequent thermal treatment at 1000°C. Durable fixation of nanoparticles on the fibre surface is confirmed by the atomic emission spectrometry with inductively coupled plasma and transmission electron microscopy. The results show that spraying of a free stream of the thermoplastic polymer melt with a gas stream containing nanoparticles allows obtaining fibre materials, which possess catalytic, photosensitive, as well as heat and sound insulating properties

Pharmacy Student Perceptions of Volunteering at a Medication Assessment Clinic Located Within a Pharmacy School

Context In 2011 the College of Pharmacy and Nutrition (University of Saskatchewan) opened a patient care clinic on campus known as the Medication Assessment Centre (MAC). The primary purpose of the MAC is to offer a faculty supervised experiential training opportunity for pharmacy students in all years of study. The early experiential education model that the MAC utilizes had not been previously evaluated in the literature. Objective The purpose of this study was to explore the experiences of MAC student volunteers. Design The perspectives of students who had volunteered at the MAC at least once between January and November 2015 were gathered through focus groups. Students were assigned to one of five focus groups based on their volunteer title and number of MAC volunteer experiences. A semi-structured focus group guide was developed and used to gather the students’ perceptions on their experiences and learning as a result of volunteering at the MAC. The focus groups were recorded and transcribed. The transcripts were analyzed by three researchers using thematic analysis. The final themes were approved by the student participants and then reviewed by an additional researcher. Results A total of 29 students participated in this study. Students perceived that the MAC had a positive effect on their learning and competence in the following areas: (1) clinical skills (patient interviewing and communication), (2) confidence, (3) clinical and therapeutic knowledge, and (4) professional socialization. Students felt the post discussion, patient care environment and actively participating were most beneficial to their learning. The aspects of the MAC that students liked most were: (1) structure of the learning experience, (2) perceived benefit to the patient, and (3) patient care environment. Students identified several challenges to participating: (1) sign up process, (2) quality of the technology, (3) remote observation, (4) limited student knowledge, (5) clarity of student role, and (6) student initial confidence. Conclusions MAC student volunteers felt that the MAC is a valuable learning experience that had a positive effect on their learning and competence. Further research should focus on confirming these findings in a larger sample and using additional methodologies such as quantitative assessments of student learning and competency

ОСНОВНІ ПЕРЕШКОДИ ЄВРОПЕЙСЬКОЇ МОБІЛЬНОСТІ МАЙБУТНІХ ФАХІВЦІВ ЕКОНОМІЧНОГО ПРОФІЛЮ (Main Obstacles to European Mobility of Future Specialists in Economics)

У статті розглянуто основні види мобільності, охарактеризовано особливі риси європейської мобільності та її відмінності від інших видів мобільності. Проаналізовано основні перешкоди мобільності студентів. (The main types of mobility were considered in the article. Specific features of European mobility and its differences from other species were described. The basic obstacles to student mobility were analyzed.