Ferromagnetism in magnetically doped III-V semiconductors

The origin of ferromagnetism in semimagnetic III-V materials is discussed. The indirect exchange interaction caused by virtual electron excitations from magnetic impurity level in the bandgap to the valence band can explain ferromagnetism in GaAs(Mn) no matter samples are degenerated or not. Formation of ferromagnetic clusters and percolation picture of phase transition describes well all available experimental data and allows to predict the Mn-composition dependence of transition temperature in wurtzite (Ga,In,Al)N epitaxial layers.Comment: 4 pages with 3 figure

Polaron percolation in diluted magnetic semiconductors

We theoretically study the development of spontaneous magnetization in diluted magnetic semiconductors as arising from a percolation of bound magnetic polarons. Within the framework of a generalized percolation theory we derive analytic expressions for the Curie temperature and the magnetization, obtaining excellent quantitative agreement with Monte Carlo simulation results and good qualitative agreement with experimental results.Comment: 5 page

Energic metabolism studies in pediatric cancer patients

The aim. To estimate heat capacity (C) measurements for individual dietary support of pediatric cancer patients during chemotherapy. Material and methods. 43 cancer children are examined. Group 1: 15 children, 5 children receiving polychemotherapy, 10 children – in post-BMT period (5 of them were re-examined on clinical indications). Thus we got 21 resting heat capacity measures. Group 2 includes 14 children with cancer after completing chemotherapy. Group 3 (control group) – 14 children with gastroenterological pathology. (C) is determined by indirect calorimetry, then basal metabolic rate (BMR) is calculated by formula BMR=90%C and compared with (Cf), calculated by formula WHO (1985). The results. In group 1 the average values of BMR and Еоф considerably differ: 986,5 and 1285,9 kcal accordingly (p<0,05). In group 2 BMR value is lower than Cf, however the difference is inconsiderable. The amount of children with decreased BMR in group 1 is considerably higher than in groups 2 and 3 – 76,2%; 42,9% and 28,6% accordingly (p<0,05). On the contrary group 3 includes more children with increased BMR, than group 1 (p<0,01). The marked decrease of heat capacity (C decrease) in group 1 is mainly associated with toxic effects of polychemotherapy and BMT on metabolic processes. Conclusion. The findings justify the need to monitor the pediatric cancer patients during special treatment to estimate their heat capacity to work out individual programs of dietary support with further assessment of effectiveness and correction

Метрологическое образование в России: итоги и перспективы

The main purposes of education and training of metrological experts based on brief review of key development stages of metrological education system were underlined. The alternate version of integration of science and education, when learning activities are realising at state scientific metrological centres was suggested. There was showed that the creation of metrological cluster for providing the education is effectually. Such clusters should consist of universities, scientific metrological institutes as well as high-schools. For the realisation of uniformity of preparation and training of potential experts on the all stages of «educational stairs» was suggested the way based on development of united teaching and learning materials on methodological support.В статье кратко рассмотрены основные этапы развития системы метрологического образования в России, выделены основные задачи при подготовке специалистов-метрологов. Предложен альтернативный вариант интеграции образования и науки при осуществлении образовательной деятельности в Государственных научных метрологических центрах. Показано, что для проведения обучения целесообразно создание метрологических кластеров. В состав кластеров предлагается включать университеты, научные метрологические институты и общеобразовательные школы. Для реализации единообразия в подготовке будущих метрологов на всех этапах образовательной пирамиды предложен подход, основанный на разработке единого учебно-методического обеспечения

Comparison of electromagnetic and nuclear dissociation of 17Ne^{17}\mathrm{Ne}

The Borromean drip-line nucleus ¹⁷Ne has been suggested to possess a two-proton halo structure in its ground state. In the astrophysical rp-process, where the two-proton capture reaction ¹⁵O(2p,γ) ¹⁷Ne plays an important role, the calculated reaction rate differs by several orders of magnitude between different theoretical approaches. To add to the understanding of the ¹⁷Ne structure we have studied nuclear and electromagnetic dissociation. A 500 MeV/u¹⁷Ne beam was directed toward lead, carbon, and polyethylene targets. Oxygen isotopes in the final state were measured in coincidence with one or two protons. Different reaction branches in the dissociation of ¹⁷Ne were disentangled. The relative populations of s and d states in ¹⁶F were determined for light and heavy targets. The differential cross section for electromagnetic dissociation (EMD) shows a continuous internal energy spectrum in the three-body system ¹⁵O + 2p. The ¹⁷Ne EMD data were compared to current theoretical models. None of them, however, yields satisfactory agreement with the experimental data presented here. These new data may facilitate future development of adequate models for description of the fragmentation process