Optimal parameters of leader development in lightning

The dependences between the different parameters of a leader in lightning are obtained theoretically. The physical mechanism of the instability leading to the formation of the streamer zone is proposed. The instability has the wave nature and is caused by the self-influence effects of the space charge. Using a stability condition of the leader propagation, a dependence is obtained between the current across the leader head and its velocity of motion. The dependence of the streamer zone length on the gap length is also obtained. It is shown that the streamer zone length is saturated with the increasing of the gap length. A comparison between the obtained dependences and the experimental data is presented

Relationship between cost of equity capital and voluntary corporate disclosures

The relationship between disclosure and cost of equity capital has always been interesting not only for managers, but for investors as well. Economic theory suggests that by increasing the level of corporate reporting firms not only increase their stock market liquidity, but they also decrease the investors’ estimation risk, arising from uncertainty about future returns and payout distributions. Utilizing the Residual Income Valuation Model, the implied cost of capital is estimated for a sample of 121 Swiss listed, non-financial companies adopting a finite horizon version of the residual income valuation model. The results show that firms on the Swiss market can reduce their cost of equity capital by increasing the level of their voluntary corporate disclosures. The results persist even after controlling for various firm specific risks, such as firm size or financial leverage and regardless of company’s reporting strategy (conservative or aggressive)

Preparation and characterization of Bi26–2xMn2xMo10O69-d and Bi26.4Mn0.6Mo10–2yMe2yO69-d(Me = V, Fe) solid solutions

Received: 06.06.2017; accepted: 23.06.2017; published: 14.07.2017.Single phase samples of bismuth molybdate, Bi26Mo10O69, doped with Mn on the bismuth sublattice and V, Fe on the molybdenum sublattice were found to crystallize in the triclinic Bi26Mo10O69 structure at low doping levels and in the monoclinic Bi26Mo10O69 structure - at higher dopant concentration. The assumption that all Mn ions have an oxidation state of +2 was confirmed by means of magnetic measurement results analysis using Curie-Weiss law. Conductivity was investigated using impedance spectroscopy. The conductivity of Bi26.4Mn0.6Mo9.6Fe0.4O69-d was 1.2*10-2 S*cm-1 at 973 K and 2.2*10-4 S*cm-1 at 623 K, and the conductivity of Bi26.4Mn0.6Mo9.2V0.8O69-d was 2.2*10-3 S*cm-1 at 973 K and 2.2*10-5 S*cm-1 at 623 K

Strength properties and structure of a submicrocrystalline Al–Mg–Mn alloy under shock compression

The results of studying the strength of a submicrocrystalline aluminum A5083 alloy (chemical composition was 4.4Mg–0.6Mn–0.11Si–0.23Fe–0.03Cr–0.02Cu–0.06Ti wt % and Al base) under shockwave compression are presented. The submicrocrystalline structure of the alloy was produced in the process of dynamic channel-angular pressing at a strain rate of 104 s–1. The average size of crystallites in the alloy was 180–460 nm. Hugoniot elastic limit σHEL, dynamic yield stress σy, and the spall strength σSP of the submicrocrystalline alloy were determined based on the free-surface velocity profiles of samples during shock compression. It has been established that upon shock compression, the σHEL and σy of the submicrocrystalline alloy are higher than those of the coarse-grained alloy and σsp does not depend on the grain size. The maximum value of σHEL reached for the submicrocrystalline alloy is 0.66 GPa, which is greater than that in the coarse-crystalline alloy by 78%. The dynamic yield stress is σy = 0.31 GPa, which is higher than that of the coarse-crystalline alloy by 63%. The spall strength is σsp = 1.49 GPa. The evolution of the submicrocrystalline structure of the alloy during shock compression was studied. It has been established that a mixed nonequilibrium grain-subgrain structure with a fragment size of about 400 nm is retained after shock compression, and the dislocation density and the hardness of the alloy are increased

ANALYSIS OF THE ABORTIONS IN BULGARIA FOR 2014

Every year, in Bulgaria nearly half of the pregnancies end up with an abortion. It is well known that every abortion hides a risk for every woman that had this kind of medical intervention. Also lowers the ability of having another pregnancy, having a healthy carrying and giving a natural childbirth. On other side, abortions are associated with being a significant factor which regulates the demografic features of the population. There is a tendency that most of the Bulgarian women use the abortion like alternative method for contraception. This is due to the fact that since 1956 there isn`t a law that prohibit the performing of abortion by choice of the pregnant woman. For the period from 1967 to 1998, many statistics show that the number of the abortions is significantly higher than the number of the actual childbirths. However, through out the next few years there is a stable tendency of dropping the number of abortions. Overall, in 2014 there is a solid tendency for the decreasing numbers of the abortions in Bulgaria between the period of 2000-2013.Every year, in Bulgaria nearly half of the pregnancies end up with an abortion. It is well known that every abortion hides a risk for every woman that had this kind of medical intervention. Also lowers the ability of having another pregnancy, having a healthy carrying and giving a natural childbirth. On other side, abortions are associated with being a significant factor which regulates the demografic features of the population. There is a tendency that most of the Bulgarian women use the abortion like alternative method for contraception. This is due to the fact that since 1956 there isn`t a law that prohibit the performing of abortion by choice of the pregnant woman. For the period from 1967 to 1998, many statistics show that the number of the abortions is significantly higher than the number of the actual childbirths. However, through out the next few years there is a stable tendency of dropping the number of abortions. Overall, in 2014 there is a solid tendency for the decreasing numbers of the abortions in Bulgaria between the period of 2000-2013

GLOBALIZATION PROCESSES IN EDUCATION (IN THE LIGHT OF THE PRIORITY PROJECT EXPORT EDUCATION»)

The paper studies the impact of globalization on the world and Russian educational services markets. The analysis of the contingents of students studying abroad. Considered social and economic aspects.Исследовано влияние глобализации на мировой и российский рынки образовательных услуг. Проведен анализ контингентов студентов, обучающихся за рубежом. Рассмотрены социальные и экономические аспекты глобализационных процессов в образовании

Distance business education through the eyes of the student

The analysis of the remote system of business education. For example, one of the business schools are considered strengths and weaknesses of distance education from the perspective of studentsПроведён анализ системы дистанционного бизнес-образования. На примере одной из бизнес-школ рассмотрены сильные и слабые стороны дистанционного образования с точки зрения студенто

Educational functions in a matrix model levels of competence

Proposed educational functions in a matrix model of levels of competence of specialists. The function describes the different types of dependencies "level of knowledge - level of experience." Testing of theoretical concepts based on a review of the reference data survey conducted among graduate students and students of master's programs distance learningПредложена образовательная функция в матричной модели уровней компетентности специалистов. Функция описывает различные типы зависимостей «уровень знаний – уровень опыта». Апробация теоретических представлений проведена на основе анализа данных референтного опроса, проведённого среди студентов-старшекурсников и слушателей магистерских программ заочной формы обучени