The long-term cyclotron dynamics of relativistic wave packets: spontaneous collapse and revival

In this work we study the effects of collapse and revival as well as {\it Zitterbewegung} (ZB) phenomenon, for the relativistic electron wave packets, which are a superposition of the states with quantum numbers sharply peaked around some level $n_0$ of the order of few tens. The probability densities as well as average velocities of the packet center and the average spin components were calculated analytically and visualized. Our computations demonstrate that due to dephasing of the states for times larger than the cyclotron period the initial wave packet (which includes the states with the positive energy only) loses the spatial localization so that the evolution can no longer be described classically. However, at the half-revival time $t=T_R/2$ its reshaping takes place firstly. The behavior of the wave packet containing the states of both energy bands (with $E_n>0$ and $E_n<0$) is more complicated. At short times of a few classical periods such packet splits into two parts which rotate with cyclotron frequency in the opposite directions and meet each other every one-half of the cyclotron period. At these moments their wave functions have significant overlap that leads to ZB. At the time of fractional revival each of two sub-packets is decomposed into few packets-fractions. However, at $t=T_R$ each of the two sub-packets (with positive or negative energy) restores at various points of the cyclotron orbit, that makes it impossible reshaping of initial wave packet entirely unlike the wave packet which consists of states with energies $E_n>0$ only. Obtained results can be useful for the description of electromagnetic radiation and absorption in relativistic plasma on astrophysics objects, where super high magnetic field has the value of the order $10^8-10^9$T, as well as for interpretation of experiments with trapped ions

Graphene superlattice with periodically modulated Dirac gap

Graphene-based superlattice (SL) formed by a periodic gap modulation is studied theoretically using a Dirac-type Hamiltonian. Analyzing the dispersion relation we have found that new Dirac points arise in the electronic spectrum under certain conditions. As a result, the gap between conduction and valence minibands disappears. The expressions for the position of these Dirac points in ${\bf k}$-space and threshold value of the potential for their emergence were obtained. At some parameters of the system, we have revealed interface states which form the top of the valence miniband.Comment: 5 pages, 4 figures, accepted to Physical Review

Миграция высококвалифицированных специалистов из России: методика оценки и тенденции

The aim  of the research  is to develop a methodology  and  assess the cross-border flows of HQs from Russia (permanent  and temporary  labor migrants),  taking  into account  the peculiarities of the legislative conditions  established  by the host country  (the criterion  of  the  entry  channel),  on  the  example  of  the  United States  and  South  Korea.Materials and  methods.  The  focus  is on  the  analysis  of  legal regimes  of  entry  in  terms  of  the  identification   of  the  category of HQs  and  the  calculation  of their number  using a situational approach. The study used general theoretical methods and statistical methods:  analysis  of the dynamics  of absolute  and  relative values.  The  information  and  statistical  base  of  the  study  was made  up of data from the Russian  State  Statistics,  data from the statistical  Agency  – Eurostat,  data  from  the  US  State  Agency for Citizenship  and Immigration, data from the Korean Statistics Agency KOSIS, data  from the Headhunter survey.Results:– Three  criteria have  been developed  on the basis of which  the evaluation  of the  number  of migrants-HQs from  Russia  can  be made.  These  are the  following: the  criterion  of the  entry  channel;  the  criterion  of income  and  the  educational  criterion.  The features of each criterion and  the possibility of its application  to estimate  the number  of HQs  who  left the country  are specified.– Identified  the boundaries  of the category of persons included in the HQs  in accordance  with  the visa regimes of the USA  and South  Korea. This  identification  has distinctive  features in each case and is determined  by the level of development  of the country for  which  the  calculation  of  the  number  of  HQs,  who  left  the country,  in this case – for Russia.– The  estimation  of the  dynamics  of the  number  of HQs,  who left Russia  to the United  States  and  South  Korea,  based  on the criterion  of  the  channel  of  entry,  that  is,  in  accordance  with the  legal conditions  of entry  of this category of persons in each country  separately.Conclusion.  The  article deals with  the methodological  problems of accounting  for the  migration  of Highly  Qualified  Specialists from Russia,  analyzes  the volume and dynamics  of their flows to individual  countries: the United  States  and  South  Korea. Estimates  of the number  of HQs  who  have  emigrated  from Russia to the United States and South  Korea,  have been calculated  based on the identification  of this category of persons in accordance  with legislative modes of entry for different specialists, established in these countries,  and  taking  into account  the peculiarities of determining the HQs contingent for Russia. If the US law provides for a separate entry  procedure  for HQs,  and  the  calculation  of their  number  is not difficult,  the legislation of South  Korea does not have  special types of visas for HQs,  so their identification  and calculation of the number  is carried  out by allocating  a range of visas,  which  were used for the persons entering the country,  representing the category of  HQs  for  Russia.  The  peculiarity  of  the  approach  used  in  the work  is also that the number of HQs,  both in the US and in South Korea,  includes  persons who  have  entered  for reasons of transfers within  companies.  Calculations  similar  to those  presented  in  this paper should be made for a number of other countries – migration partners of Russia,  which  will make  it possible to obtain an overall estimate  of the number  of HQs  who  left Russia  and  to assess the loss of human  capital.Цель работы: разработать  методику  и оценить трансграничные потоки ВКС из России (постоянных и временных  трудовых мигрантов), с учетом  особенностей  законодательных условий въезда, установленных принимающей страной (критерий канала въезда),  на примере США и Южной  Кореи.Материалы  и методы:  Основное  внимание  сосредоточено  на анализе  нормативно-правовых режимов  въезда с точки  зрения идентификации  категории  ВКС  и  расчета  их  численности с применением  ситуационного подхода. В исследовании  были использованы   общетеоретические методы  и  статистические методы:  анализ  динамики абсолютных   и  относительных величин. Информационно-статистическую базу исследования составили данные Российской государственной статистики, данные статистического агентства Eurostat,  данные государственного агентства США по гражданству  и иммиграции, данные Корейского  агентства по статистике KOSIS,  данные опроса агентства HeadHunter.Результаты:– Разработаны  три  критерия, на основе которых  могут  быть произведены оценки численности  мигрантов-ВКС из России, это: критерий  канала  въезда; критерий  дохода и образовательный критерий.  Указаны  особенности  каждого критерия  и возможности его применения  для оценки численности выехавших из страны ВКС.– Идентифицированы  границы  категории  лиц,   входящих   в состав  ВКС  в  соответствии с визовыми  режимами  США  и Южной  Кореи.  Подобная  идентификация имеет  отличительные особенности  в каждом  конкретном случае  и определяется уровнем развития страны, для которой производится расчет численности  выехавших ВКС,  в данном случае  – для России.– Произведена оценка  динамики численности  ВКС,  выехавших из России в США и Южную  Корею,  на основе критерия  канала въезда,  то есть в соответствии с нормативно-правовыми условиями   въезда  данной  категории лиц  в  каждую  страну  в отдельности.Заключение:  В статье рассмотрены методологические проблемы учета миграции высококвалифицированных специалистов из России, дан анализ объемов и динамики их потоков  в отдельные страны: США и Южную  Корею.Оценки   численности   ВКС,   выехавших  из  России  в  США  и Южную Корею, рассчитаны  на основе идентификации данной категории лиц в соответствии с законодательными режимами въезда для различных  специалистов, установленными в данных странах, и с учетом  особенностей  определения  контингента ВКС  для России.  Если  законодательство США  предусматривает отдельный порядок въезда для ВКС, и расчет их численности  не представляет сложности,  то законодательство Южной Кореи не имеет специальных типов виз для ВКС, поэтому  их  идентификация и расчет  численности  осуществляется  благодаря выделению диапазона  виз, по которым въехали лица, представляющие для России категорию ВКС. Особенность применяемого  в работе подхода состоит также в том,  что к численности  ВКС,  как  в США,  так  и в Южной Корее, отнесены лица, въехавшие по причинам переводов внутри компаний. Расчеты,  аналогичные  представленному  в  данной работе, необходимо произвести  для ряда других стран-миграционных  партнеров  России,  что даст возможность  получить общую оценку численности  выехавших из России ВКС и оценить потери  человеческого  капитала

Correlation of the level of development of academic autonomy of younger students with indicators of educational motivation and style of pedagogical activity (on the example of primary school students in Uzbekistan)

Primary school age, according to most researchers, is the most sensitive for the development of academic autonomy and educational motivation, which are key factors for the success of educational activities. The authors of the article suggested that the formation of student autonomy is associated with the learning environment, the nature of changes in the motivational sphere of the child's personality, including the predominance of internal or external motivation. The study was performed on a sample of 134 students and 18 teachers of schools in Uzbekistan. As diagnostic tools were: the method of “Diagnostics of level of school motivation in elementary school students” N. G. Lukanova, the method of “Diagnosis of educational autonomy of younger school student” S. Yu. Prokhorov, the method “Style of teaching” A. M. Markova and A. I. Nikonova. Previously, the methods were adapted for the Uzbek sample. The calculation of the x2 criterion was used as the main statistical tool. As a result of the study, a statistically reliable relationship was established between the indicators of educational motivation and the level of academic autonomy of younger students. The researchers found that the incentive for learning activities can be external motivation, that is, the motivation to avoid failure and Vice versa. Younger students with high and above-average levels of academic autonomy are mostly trained in teacher classes that ensure that students focus on both the content aspects of the material being studied motivation, psychological and pedagogical support of educational activities and on achieving their goals, and who are less likely to focus on assessing the failures of their students. Based on the results obtained, the article formulates pedagogical and psychological directions of work for the successful development of academic autonomy and educational motivation of primary school students.Младший школьный возраст, по мнению большинства исследователей, является наиболее сензитивным для развития академической самостоятельности и учебной мотивации, выступающих ключевыми факторами успешности образовательной деятельности. Авторы статьи предположили, что формирование самостоятельности учащегося связано с условиями обучения, характером изменений в мотивационной сфере личности ребенка, в том числе, в преобладании внутренней или внешней мотивации. Исследование выполнено на выборке 134 учащихся и 18 педагогов школ Узбекистана. В качестве диагностических средств выступили: методика «Диагностика уровня школьной мотивации учащихся начальной школы» Н. Г. Лускановой, методика «Диагностика учебной самостоятельности младшего школьника» С. Ю. Прохорова, методика «Стиль педагогической деятельности» А. М. Марковой и А. Я. Никоновой. Предварительно была проведена адаптация методик для узбекской выборки. В качестве основного статистического инструмента использовался расчет критерия Х2. В результате исследования была установлена статистически достоверная взаимосвязь между показателями учебной мотивации и уровнем академической самостоятельности младших школьников. Исследователи выявили, что стимулом учебной деятельности может быть внешняя мотивация, то есть мотивация избегать неудачи и наоборот. Младшие школьники с высокими и выше среднего показателями академической самостоятельности в основном обучаются в классах учителей, обеспечивающих сосредоточенность обучающихся как на содержательных аспектах изучаемого материала, так и на достижении целей своей деятельности, и которые менее склонны акцентировать внимание на оценке неудач своих учеников. На основании полученных результатов в статье сформулированы педагогические и психологические направления работы для успешного развития академической самостоятельности и учебной мотивации учащихся младших классов

Proving Craig and Lyndon Interpolation Using Labelled Sequent Calculi

We have recently presented a general method of proving the fundamental logical properties of Craig and Lyndon Interpolation (IPs) by induction on derivations in a wide class of internal sequent calculi, including sequents, hypersequents, and nested sequents. Here we adapt the method to a more general external formalism of labelled sequents and provide sufficient criteria on the Kripke-frame characterization of a logic that guarantee the IPs. In particular, we show that classes of frames definable by quantifier-free Horn formulas correspond to logics with the IPs. These criteria capture the modal cube and the infinite family of transitive Geach logics

Study of social tension based on electronic social networks big data

The article presents a methodology for assessing the level of social tension according to the data of electronic social networks. The calculation of the level of social tension according to the specified method is carried out automatically using software tools and requires the participation of the researcher only at the level of an analytical conclusion. An approach to identifying the dissatisfaction of the population at the level of the simplest actions of social network accounts has been described in detail. The necessity of identifying certain spheres of public life for the identification of population discontent has been substantiated, the indicated spheres have been highlighted and described. An indicator has been developed that makes it possible to calculate the level of social tension within each of the identified spheres of public life, taking into account the level of negative messages (posts and comments) and the discussion of each topic. A generalising indicator of the level of social tension has been developed, combining individual indicators of tension by topic. The calculation of the generalising indicator makes it possible to identify the level of social tension in a region or other territorial entity and track its dynamics in any perspective, including retrospectively.The proposed methodology for assessing social tension based on data from electronic social networks differs significantly from existing sociological and statistical approaches. Its main advantage lies in the minimal time lag between the dynamics of social tension, reflected in the social network, and its identification, which expands the possibilities of a prompt response to the growth of negative moods in society. Another difference of the proposed approach is the possibility of multiple repetitions of calculations with minimal, in contrast to the sociological method, the cost of additional resources for each subsequent iteration of the calculation of the indicator value

INFLUENCE OF BIOLOGIC AND SOCIAL FACTORS ON WORKING CAPABILITY OF WORKERS OF BRAINWORK

Questionnaire of 285 teachers of comprehensive schools estimated subjective fatigue and possibilities of restoration of working capacity depending on a number of biological and. social factors. From among studied factors the greatest contribution to efficiency of workers of brainwork is brought by indicators of a state of health, in particular chronic incidence, frequency of diseases in a year and. value judgment of health. The age of the worker and. level of satisfaction of the general and. professional requirements have a certain value

Characterization of the matrix and fusion crust of the recent meteorite fall Ozerki L6

We studied the interior and the fusion crust of the recently recovered Ozerki L6 meteorite using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy, X-ray diffraction (XRD), magnetization measurements, and Mossbauer spectroscopy. The phase composition of the interior and of the fusion crust was determined by means of SEM, XRD, and Mossbauer spectroscopy. The unit cell parameters for silicate crystals were evaluated from the X-ray diffractograms and were found the same for the interior and the fusion crust. Magnetization measurements revealed a decrease of the saturation magnetic moment in the fusion crust due to a decrease of Fe-Ni-Co alloy content. Both XRD and Mossbauer spectroscopy show the presence of magnesioferrite in the fusion crust. The temperatures of cation equilibrium distribution between the M1 and M2 sites in silicates calculated using the data obtained from XRD and Mossbauer spectroscopy appeared to be in a good consistency: 553 and 479 K for olivine and 1213 and 1202 K for orthopyroxene.Peer reviewe

Properties of silicon dioxide layers with embedded metal nanocrystals produced by oxidation of Si:Me mixture

A two-dimensional layers of metal (Me) nanocrystals embedded in SiO2 were produced by pulsed laser deposition of uniformly mixed Si:Me film followed by its furnace oxidation and rapid thermal annealing. The kinetics of the film oxidation and the structural properties of the prepared samples were investigated by Rutherford backscattering spectrometry, and transmission electron microscopy, respectively. The electrical properties of the selected SiO2:Me nanocomposite films were evaluated by measuring C-V and I-V characteristics on a metal-oxide-semiconductor stack. It is found that Me segregation induced by Si:Me mixture oxidation results in the formation of a high density of Me and silicide nanocrystals in thin film SiO2 matrix. Strong evidence of oxidation temperature as well as impurity type effect on the charge storage in crystalline Me-nanodot layer is demonstrated by the hysteresis behavior of the high-frequency C-V curves

Detection of diphtheria antitoxin by four different methods

ObjectiveTo investigate the reliability of the different methods used in Norway and Russia for detection of diphtheria antitoxin.MethodsOne hundred and twenty-two sera were selected among Russian serum samples previously collected for seroepidemiologic studies of diphtheria antitoxin. The sera were selected to cover the total antitoxin range and were analyzed by four different antidiphtheria toxin assays: an in vitro toxin neutralization test using Vero cells (in vitro NT), an in vivo neutralization test using rabbit skin inoculation (in vivo NT), an indirect enzyme immunoassay (EIA) and a passive hemagglutination assay (PHA). The results were expressed according to the international standard as: not protected (<0.01 IU/mL), relatively protected (0.01–0.1 IU/mL) or protected (≤0.1 IU/mL). The sensitivity, specificity and inter-rater agreement (K or Kw) of each method were related to the in vitro NT selected as the reference method.ResultsThe in vivo NT test corresponded very well with the in vitro NT in its ability to differentiate between protection/relative protection and no protection (sensitivity 97%, specificity 87% and K=0.84). The EIA test showed a high sensitivity (96%), but since many sera were categorized as protected rather than not protected, the specificity (30%) and inter-rater agreement (K=0.29) were low. The PHA test had a very high specificity (100%) but a low sensitivity (86%).ConclusionsThe agreement between the two neutralization tests was high. If none of the neutralization assays is routinely available, the PHA test can be used to predict the need for vaccination on an individual basis but should not be used for seroepidemiologic studies, since the protection rate for diphtheria would be falsely too low, due to the lower sensitivity. The indirect EIA test used in this study should not be used routinely