High-visibility multi-photon interference of Hanbury Brown - Twiss type for classical light

Difference-phase (or Hanbury Brown - Twiss type) intensity interference of classical light is considered in higher orders in the intensity. It is shown that, while the visibility of sum-phase (NOON-type) interference for classical sources drops with the order of interference, the visibility of difference-phase interference has opposite behavior. For three-photon and four-photon interference of two coherent sources, the visibility can be as high as 81.8% and 94.4%, respectively. High-visibility three-photon and four-photon interference of space-time and polarization types has been observed in experiment, for both coherent and pseudo-thermal light.Comment: 11 pages, 9 figure

Possibility of local pair existence in optimally doped SmFeAsO(1-x) in pseudogap regime

We report the analysis of pseudogap Delta* derived from resistivity experiments in FeAs-based superconductor SmFeAsO(0.85), having a critical temperature T_c = 55 K. Rather specific dependence Delta*(T) with two representative temperatures followed by a minimum at about 120 K was observed. Below T_s = 147 K, corresponding to the structural transition in SmFeAsO, Delta*(T) decreases linearly down to the temperature T_AFM = 133 K. This last peculiarity can likely be attributed to the antiferromagnetic (AFM) ordering of Fe spins. It is believed that the found behavior can be explained in terms of Machida, Nokura, and Matsubara (MNM) theory developed for the AFM superconductors.Comment: 5 pages, 2 figure

Reconstructing Images from Projections Using the Maximum-Entropy Method. Numerical Simulations of Low-Aspect Astrotomography

The reconstruction of images from a small number of projections using the maximum-entropy method (MEM) with the Shannon entropy is considered. MEM provides higher-quality image reconstruction for sources with extended components than the Hogbom CLEAN method, which is also used in low-aspect astrotomography. The quality of image reconstruction for sources with mixed structure containing bright, compact features embedded in a comparatively weak, extended base can be further improved using a difference-mapping method, which requires a generalization of MEM for the reconstruction of sign-variable functions.We draw conclusions based on the results of numerical simulations for a number of model radio sources with various morphologies.Comment: 11 pages, 9 figure

Photocatalytic activity of titania nanopowders prepared by a sol–gel process at various pHs

A strategy has been proposed to prepare photocatalytically active titania nanopowders through a sol-gel route using high-degree molecular separation upon the dilution of reagents, high water/alkoxide ratios, high reagent mixing rates, and pH effects. This strategy has been successfully used to isolate, from sols, anatase powders with high surface areas (100–310 m2/g) dependent on the pH value during the synthesis. The photocatalytic activity of titania nanopowders prepared by the sol-gel process at various pHs has been tested in photodestruction of organic dyes (Rodamine B, Methylene Blue, and Anthraquinone AcidBlue) in acid solutions. UV-radiation-induced dye destruction rates are found to depend on the surface properties (including surface area and ζ potential) and hydration specifics of the titania

Development of the activity of gifted schoolchildren in mastering geometric con-cepts in figurative structures

Background: The relevance of developing mental activity for mastering geometric concepts relates to the change in paradigmatic foundations taking place in modern education. Such a change is associated with the recognition of a schoolchild as a subject of educational and cognitive activity, the initiator of own activity. Objective: The authors attempted to describe a model of a didactic system for developing active usage of geometric concepts in the process of teaching geometry to mathematically gifted schoolchildren in 10-11 grades. The authors also used the GeoGebra dynamic system as a component of the electronic educational environment (EEE). The objective is achieved by characterizing the architecture of the system model, which evokes active usage of geometric concepts within schoolchildren in learning situations; substantiating psychodidactic conditions for the effective development of this activity using the GeoGebra dynamic system; and defining levels, criteria, and indicators of development. Methods: A specially organized educational activity in EEE and a developed system of tasks within the framework of the elective course “Problems of solid geometry and computer graphics” for 10-11 graders represent a didactic means of developing the activities related to figurative-spatial methods of information coding. Findings: The authors described a didactic system model for mastering geometric concepts in figurative structures in the process of teaching geometry to 10-11 graders using the GeoGebra dynamic system. Conclusions: Fostering schoolchildren’ mastering geometric concepts in figurative structures occurs under the direct influence of teaching. However, this process is complex and internally contradictory. The structure of this kind of activity contains actions of different nature

Development of the activity of gifted schoolchildren in mastering geometric con-cepts in figurative structures

Background: The relevance of developing mental activity for mastering geometric concepts relates to the change in paradigmatic foundations taking place in modern education. Such a change is associated with the recognition of a schoolchild as a subject of educational and cognitive activity, the initiator of own activity. Objective: The authors attempted to describe a model of a didactic system for developing active usage of geometric concepts in the process of teaching geometry to mathematically gifted schoolchildren in 10-11 grades. The authors also used the GeoGebra dynamic system as a component of the electronic educational environment (EEE). The objective is achieved by characterizing the architecture of the system model, which evokes active usage of geometric concepts within schoolchildren in learning situations; substantiating psychodidactic conditions for the effective development of this activity using the GeoGebra dynamic system; and defining levels, criteria, and indicators of development. Methods: A specially organized educational activity in EEE and a developed system of tasks within the framework of the elective course “Problems of solid geometry and computer graphics” for 10-11 graders represent a didactic means of developing the activities related to figurative-spatial methods of information coding. Findings: The authors described a didactic system model for mastering geometric concepts in figurative structures in the process of teaching geometry to 10-11 graders using the GeoGebra dynamic system. Conclusions: Fostering schoolchildren’ mastering geometric concepts in figurative structures occurs under the direct influence of teaching. However, this process is complex and internally contradictory. The structure of this kind of activity contains actions of different nature

Cоциокультурный подход к формированию геометрических понятий у школьников

In line with the social and cultural approach, the problem of forming mathematical concepts among schoolchildren as the system of judgments is considered. Concepts at the verbal and logical level are formed through teaching to prove theorems and solve proof problems. Objective: To provide elements of the method of forming geometric concepts by means of specially organized learning activities of schoolchildren to develop the generalized ability to prove with the access to the value-oriented learning. Methods: Theoretical provisions on the laws of the concept formation process are developed. During the experiment forming stage the methodology to teach geometry to pupils of the 7th grade of secondary education institutions is developed. The basis is the activity to develop skills to prove. Relying on instrument-oriented, subject-oriented and value-oriented types of learning is assumed. Findings: During the quantitative and qualitative evaluation of results, the following independent characteristics have been taken into account: the form of action, the level of generalization, the level of expansion, the level of mastering, and the value relation. The results of analyzing the statistical data hav e confirmed the hypothesis about the significant influence of the following factors on the success of mastering geometric concepts by pupils: the mathematical training (significance level 0,003), the effect of electronic educational environment in combination with the evaluated method (significance level 0,001), the duration of training using the evaluated method (significance level 0,01). Conclusions: The hypothesis is substantiated and proved in practice: the process of forming concepts is regularly ensured by the following psychodidactic conditions: the formation of main components of conceptual psychic structures; the formation of declarative, procedural and evaluative knowledge; the gradual formation of the subjective image of the concept content; the gradual development of the entire psychic structure; the gradual development of the activity component of geometric concepts.En línea con el enfoque social y cultural, se considera el problema de formar conceptos matemáticos entre los escolares como el sistema de juicios. Los conceptos a nivel verbal y lógico se forman a través de la enseñanza para probar teoremas y resolver problemas de prueba. Objetivo: Proporcionar elementos del método de formación de conceptos geométricos por medio de actividades de aprendizaje especialmente organizadas de los escolares para desarrollar la capacidad generalizada de demostrar con el acceso al aprendizaje orientado a valores. Métodos: Se desarrollan disposiciones teóricas sobre las leyes del proceso de formación de conceptos. Durante la fase de formación del experimento, se desarrolla la metodología para enseñar geometría a alumnos de 7º grado de instituciones de educación secundaria. La base es la actividad para desarrollar habilidades para demostrar. Se supone que se depende de los tipos de aprendizaje orientados a instrumentos, orientados a la materia y orientados al valor. Resultados: Durante la evaluación cuantitativa y cualitativa de los resultados, se han tenido en cuenta las siguientes características independientes: la forma de acción, el nivel de generalización, el nivel de expansión, el nivel de dominio y la relación de valor. Los resultados del análisis de los datos estadísticos han confirmado la hipótesis sobre la influencia significativa de los siguientes factores en el éxito del dominio de los conceptos geométricos por parte de los alumnos: la formación matemática (nivel de significación 0,003), el efecto del entorno educativo electrónico en combinación con el método evaluado (nivel de significación 0,001), la duración de la capacitación utilizando el método evaluado (nivel de significación 0,01). Conclusiones: La hipótesis está fundamentada y demostrada en la práctica: el proceso de formación de conceptos se garantiza regularmente mediante las siguientes condiciones psicodidácticas: la formación de los componentes principales de las estructuras psíquicas conceptuales; la formación del conocimiento declarativo, procesal y evaluativo; la formación gradual de la imagen subjetiva del concepto de contenido; el desarrollo gradual de toda la estructura psíquica; El desarrollo gradual del componente de actividad de los conceptos geométricos.История вопроса. В русле социокультурного подхода рассматривается проблема формирования математических понятий у школьников как системы суждений. Формирование понятий на вербально-логическом уровне осуществляется через обучение доказательству теорем и решению задач на доказательства. Цель (Objective): Представить элементы технологии формирования геометрических понятий средствами специально организованной учебной деятельности школьников по освоению обобщенного умения доказывать с выходом в ценностно-ориентированное обучение. (Methods): Разработаны теоретические положения о закономерностях процесса формирования понятий. В ходе формирующего этапа эксперимента разработана методика обучения геометрии учащихся 7-х классов среднеобразовательных учреждений. В качестве основы выступала деятельность по освоению умений доказывать. Предполагалась опора на инструментально-ориентированный, предметно-ориентированный и ценностно-ориентированный типы обучения. Результаты (Findings): При проведении количественной и качественной оценки результатов учитывались независимые характеристики: форма действия, степень обобщения, мера развернутости, мера освоения и ценностное отношение. Результаты анализа статистических данных подтвердили гипотезу о значимом влиянии следующих факторов на успешность освоения обучающимся геометрических понятий: математическая подготовка (уровень значимости 0,003), влияние электронной образовательной среды в сочетании с апробируемой методикой (уровень значимости 0,001), продолжительность обучения с использованием апробируемой методики (уровень значимости 0,01). Выводы (Conclusions): Обоснована и на практике подтверждена гипотеза: процесс формирования понятий закономерно обеспечивается следующими психодидактическими условиями: формирование основных компонентов понятийных психических структур; формирование декларативных, процедурных и оценочных знаний; пофазовое формирование субъективного образа содержания понятия; поэтапное развитие целостной психической структуры; поэтапное развитие деятельностной компоненты геометрических понятий