Bose-Einstein statistics in thermalization and photoluminescence of quantum well excitons

Quasi-equilibrium relaxational thermodynamics is developed to understand LA-phonon-assisted thermalization of Bose-Einstein distributed excitons in quantum wells. We study the quantum-statistical effects in the relaxational dynamics of the effective temperature of excitons $T = T(t)$. When $T$ is less than the degeneracy temperature $T_0$, well-developed Bose-Einstein statistics of quantum well excitons leads to nonexponential and density-dependent thermalization. At low bath temperatures $T_b \to 0$ the thermalization of quantum-statistically degenerate excitons effectively slows down and $T(t) \propto 1 / \ln t$. We also analyze the optical decay of Bose-Einstein distributed excitons in perfect quantum wells and show how nonclassical statistics influences the effective lifetime $\tau_{opt}$. In particular, $\tau_{opt}$ of a strongly degenerate gas of excitons is given by $2 \tau_R$, where $\tau_R$ is the intrinsic radiative lifetime of quasi-two-dimensional excitons. Kinetics of resonant photoluminescence of quantum well excitons during their thermalization is studied within the thermodynamic approach and taking into account Bose-Einstein statistics. We find density-dependent photoluminescence dynamics of statistically degenerate excitons. Numerical modeling of the thermalization and photoluminescence kinetics of quasi-two-dimensional excitons are given for GaAs/AlGaAs quantum wells.Comment: 19 pages, 9 figures. Phys. Rev. B (accepted for publication

Spatio-temporal dynamics of quantum-well excitons

We investigate the lateral transport of excitons in ZnSe quantum wells by using time-resolved micro-photoluminescence enhanced by the introduction of a solid immersion lens. The spatial and temporal resolutions are 200 nm and 5 ps, respectively. Strong deviation from classical diffusion is observed up to 400 ps. This feature is attributed to the hot-exciton effects, consistent with previous experiments under cw excitation. The coupled transport-relaxation process of hot excitons is modelled by Monte Carlo simulation. We prove that two basic assumptions typically accepted in photoluminescence investigations on excitonic transport, namely (i) the classical diffusion model as well as (ii) the equivalence between the temporal and spatial evolution of the exciton population and of the measured photoluminescence, are not valid for low-temperature experiments.Comment: 8 pages, 6 figure

O conceito de criação de territórios de desenvolvimento socioeconômico avançado

The article is devoted to the development of the concept of creation and functioning of the advanced socio-economic development territories. The relevance of the study is due to the need to develop the theoretical aspects of creating a new development institution in view of the lack of consensus between theorists and practitioners regarding both the need for a special form of a special territory and the mechanisms for achieving the goals. The hypothesis of the study is that the space of basic features, within which the formation of the advanced socio-economic development territories should be considered, can be structured on the basis of the dichotomous method.On the basis of diagnostics of indicators (2011-2016) of the socio-economic development of monocities and Far Eastern territories that have received the status of territories with a special mode of introducing entrepreneurial activity, and analysis of Russian legislation, national and foreign experience of territorial development, the authors constructed a problematic field for the creation of advanced socio-economic development in the form of a system of basic variables. The proposed conceptual model is designed to focus attention on the elaboration of the theoretical foundation for the creation of advanced socio-economic development territories, to limit and rationally optimize the process of their creation and functioning so that the government officials receive an effective mechanism for structuring the main stages of the state project implementation on creating a territory with a special introduction mode of business activities.El artículo está dedicado al desarrollo del concepto de creación y funcionamiento de los territorios de desarrollo socioeconómico avanzado. La relevancia del estudio se debe a la necesidad de desarrollar los aspectos teóricos de la creación de una nueva institución de desarrollo en vista de la falta de consenso entre los teóricos y los profesionales con respecto a la necesidad de una forma especial de territorio especial y los mecanismos para lograr las metas. La hipótesis del estudio es que el espacio de características básicas, dentro del cual debe considerarse la formación de territorios de desarrollo socioeconómico avanzado, puede estructurarse sobre la base del método dicotómico.Sobre la base del diagnóstico de los indicadores (2011-2016) del desarrollo socioeconómico de las ciudades y territorios del Lejano Oriente que han recibido el estatus de territorios con un modo especial de introducción de actividades empresariales, y análisis de la legislación rusa, experiencia nacional y extranjera. De desarrollo territorial, los autores construyeron un campo problemático para la creación de un desarrollo socioeconómico avanzado en forma de un sistema de variables básicas. El modelo conceptual propuesto está diseñado para centrar la atención en la elaboración de los fundamentos teóricos para la creación de territorios de desarrollo socioeconómico avanzado, para limitar y optimizar racionalmente el proceso de su creación y funcionamiento para que los funcionarios del gobierno reciban un mecanismo eficaz para estructurar las etapas principales de la implementación del proyecto estatal para crear un territorio con un modo especial de introducción de actividades comerciales.O artigo é dedicado ao desenvolvimento do conceito de criação e funcionamento dos territórios avançados de desenvolvimento socioeconômico. A relevância do estudo deve-se à necessidade de desenvolver os aspectos teóricos da criação de uma nova instituição de desenvolvimento, tendo em vista a falta de consenso entre teóricos e profissionais sobre a necessidade de uma forma especial de território especial e os mecanismos para alcançar a objetivos. A hipótese do estudo é que o espaço das características básicas, dentro do qual a formação dos territórios avançados de desenvolvimento socioeconômico deve ser considerado, pode ser estruturado com base no método dicotômico.Com base no diagnóstico de indicadores (2011-2016) do desenvolvimento socioeconômico de monocidades e territórios do Extremo Oriente que receberam o status de territórios com um modo especial de introduzir a atividade empreendedora, e análise da legislação russa, experiência nacional e estrangeira do desenvolvimento territorial, os autores construíram um campo problemático para a criação de desenvolvimento socioeconômico avançado na forma de um sistema de variáveis básicas. O modelo conceitual proposto visa chamar a atenção para a elaboração dos fundamentos teóricos para a criação de territórios avançados de desenvolvimento socioeconômico, para limitar e racionalizar o processo de sua criação e funcionamento, para que os funcionários públicos recebam um mecanismo efetivo de estruturação. as principais etapas da implementação do projeto estadual na criação de um território com um modo especial de introdução de atividades empresariais

O conceito e os meios de controle de processos de aglomeração

Within this article, we considered the theoretical and empirical approaches to the understanding of agglomeration processes, highlighted the main foreign and domestic paradigms for classifying territories as agglomerations, as well as studied the works of the authors who first introduced the concept of “agglomeration”. It has been found that the foreign authors most often interpret the concept according to geographical, administrative and economic approaches, while the domestic literature uses an economic-geographical appr oach. At the same time, the formation of agglomerations is based on the development potential of territories, and the agglomeration processes actively influence the factors of a territory development.At the present stage of development of agglomerations abroad, the potential and effectiveness of the agglomeration processes based on the benchmarking research are being actively studied. At the same time, foreign scientists identify various aspects for controlling the agglomeration development process. The article highlights the problem of the lack of the agglomeration development concept in Russia at the federation level, which hampers the development of relevant documents at the regional and territorial levels. The development of this concept is proposed to begin with the scheme of regulatory and legal support for the agglomeration development. There are three interrelated stages in the proposed scheme: the development of a specific agglomeration development strategy, the creation of a scheme for its territorial planning, the formation of a comprehensive investment program for agglomeration.En este artículo, consideramos los enfoques teóricos y empíricos para la comprensión de los procesos de aglomeración, destacamos los principales paradigmas extranjeros y nacionales para clasificar los territorios como aglomeraciones, y estudiamos los trabajos de los autores que introdujeron por primera vez el concepto de "aglomeración". Se ha encontrado que los autores extranjeros a menudo interpretan el concepto de acuerdo con los enfoques geográficos, administrativos y económicos, mientras que la literatura nacional utiliza un enfoque económico-geográfico. Al mismo tiempo, la formación de aglomeraciones se basa en el potencial de desarrollo de los territorios, y los procesos de aglomeración influyen activamente en los factores del desarrollo de un territorio.En la etapa actual del desarrollo de aglomeraciones en el extranjero, se están estudiando activamente el potencial y la eficacia de los procesos de aglomeración basados en la investigación de evaluación comparativa. Al mismo tiempo, científicos extranjeros identifican varios aspectos para controlar el proceso de desarrollo de la aglomeración. El artículo destaca el problema de la falta del concepto de desarrollo de aglomeración en Rusia a nivel de federación, lo que dificulta el desarrollo de documentos relevantes a nivel regional y territorial. Se propone el desarrollo de este concepto para comenzar con el esquema de apoyo legal y regulatorio para el desarrollo de la aglomeración. Hay tres etapas interrelacionadas en el esquema propuesto: el desarrollo de una estrategia específica de desarrollo de aglomeración, la creación de un esquema para su planificación territorial, la formación de un programa de inversión integral para la aglomeración.Dentro deste artigo, consideramos as abordagens teóricas e empíricas para a compreensão dos processos de aglomeração, destacamos os principais paradigmas nacionais e estrangeiros para classificar os territórios como aglomerações, bem como estudamos os trabalhos dos autores que primeiro introduziram o conceito de “aglomeração”. Verificou-se que os autores estrangeiros interpretam mais frequentemente o conceito de acordo com abordagens geográficas, administrativas e econômicas, enquanto a literatura nacional utiliza uma abordagem econômico-geográfica. Ao mesmo tempo, a formação de aglomerações baseia-se no potencial de desenvolvimento dos territórios, e os processos de aglomeração influenciam ativamente os fatores de desenvolvimento de um território.No estágio atual de desenvolvimento de aglomerações no exterior, o potencial e a eficácia dos processos de aglomeração baseados na pesquisa de benchmarking estão sendo ativamente estudados. Ao mesmo tempo, cientistas estrangeiros identificam vários aspectos para controlar o processo de desenvolvimento da aglomeração. O artigo destaca o problema da falta do conceito de desenvolvimento da aglomeração na Rússia no nível da federação, o que dificulta o desenvolvimento de documentos relevantes nos níveis regional e territorial. O desenvolvimento deste conceito é proposto para começar com o esquema de apoio regulatório e legal para o desenvolvimento da aglomeração. Há três estágios inter-relacionados no esquema proposto: o desenvolvimento de uma estratégia específica de desenvolvimento de aglomeração, a criação de um esquema para seu planejamento territorial, a formação de um programa abrangente de investimento para aglomeração

Sobre la reforma de la propiedad de la tierra en el contexto de las posibilidades heurísticas.

El artículo incluye las consecuencias de la reforma de la propiedad de la tierra implementada desde los años 90 y sus fundamentos conceptuales, así como un concepto constructivo para su ajuste sustancial. Se muestran tendencias de crecimiento en el marco de la norma de reforma agraria implementada, y se concluye que un cambio en la situación actual de las relaciones de propiedad de la tierra no está relacionado con la forma de propiedad, sino con un rechazo decisivo de los postulados ultra-liberales y el desarrollo del concepto de ajuste de la reforma agraria, además, que una política nacional efectiva de propiedad de la tierra y que sus relaciones de propiedad son el eslabón más débil en la economía agraria rusa.

Clasificación de Territorios de Desarrollo Socioeconómico Avanzado.

La experiencia nacional y extranjera en el desarrollo de territorios con estatus legal especial para realizar actividades empresariales ha demostrado, que la efectividad de estas instituciones depende de factores, que deben ser estudiados y analizados en detalle. El artículo presenta la clasificación Territorios con Desarrollo Socioeconómico Avanzado (TDSEA) según el potencial del desarrollo industrial, y se propone evaluar el potencial del desarrollo industrial de acuerdo con el nivel de desarrollo socioeconómico, ubicación geográfica y nivel tecnológico predominante de la producción urbana. El análisis de los indicadores de monociudades especiales mostró que la mayoría de ellas se encontraba en una situación socioeconómica difícil, donde las más vulnerables fueron "Nadvoitsy", "Anzhero-Sudzhensk", y "Krasnoturinsk" y aquellas con TASED fueron "Nizhnekamsk", "Sosensky", "Tutaev"

Pediatric Ovarian Torsion and its Recurrence: A Multicenter Study

Study Objective: To report results of a retrospective multicentric Italian survey concerning the management of pediatric ovarian torsion (OT) and its recurrence.Design: Multicenter retrospective cohort study.Setting: Italian Units of Pediatric Surgery.Participants: Participants were female aged 1-14 years of age with surgically diagnosed OT between 2004 and 2014. Interventions: Adnexal detorsion, adnexectomy, mass excision using laparoscopy or laparotomy. Different kinds of oophoropexy (OPY) for OT or recurrence, respectively.Main Outcome Measures: A total of 124 questionnaires were returned and analyzed to understand the current management of pediatric OT and its recurrence. The questionnaires concerned patient age, presence of menarche, OT site, presence and type of mass, performed procedure, OPY technique adopted, intra-and postoperative complications, recurrence and site, procedure performed for recurrence, OPY technique for recurrence, and 1 year follow-up of detorsed ovaries.Results: Mean age at surgery was 9.79 +/- 3.54 years. Performed procedures were open adnexectomy (52 of 125; 41.6%), laparoscopic adnexectomy (25 of 125; 20%), open detorsion (10 of 125; 8%), and laparoscopic detorsion (38 of 125; 30.4%). Recurrence occurred in 15 of 125 cases (12%) and resulted as significant (P =.012) if associated with a normal ovary at the first episode of torsion. Recurrence occurred only in 1 of 19 cases after OPY (5.2%). Ultrasonographic results of detorsed ovaries were not significant whether an OPY was performed or not (P = 1.00).Conclusion: Unfortunately, oophorectomy and open technique are still widely adopted even if not advised. Recurrence is not rare and the risk is greater in patients without ovarian masses. OPY does not adversely affect ultrasonographic results at 1 year. When possible OPY should be performed at the first episode of OT

Insulin-Like Peptides and the Target of Rapamycin Pathway Coordinately Regulate Blood Digestion and Egg Maturation in the Mosquito Aedes aegypti

Mosquitoes are insects that vector many serious pathogens to humans and other vertebrates. Most mosquitoes must feed on the blood of a vertebrate host to produce eggs. In turn, multiple cycles of blood feeding promote frequent contacts with hosts and make mosquitoes ideal disease vectors. Both hormonal and nutritional factors are involved in regulating egg development in the mosquito, Aedes aegypti. However, the processes that regulate digestion of the blood meal remain unclear.Here we report that insulin peptide 3 (ILP3) directly stimulated late phase trypsin-like gene expression in blood fed females. In vivo knockdown of the mosquito insulin receptor (MIR) by RNA interference (RNAi) delayed but did not fully inhibit trypsin-like gene expression in the midgut, ecdysteroid (ECD) production by ovaries, and vitellogenin (Vg) expression by the fat body. In contrast, in vivo treatment with double-stranded MIR RNA and rapamycin completely blocked egg production. In vitro experiments showed that amino acids did not simulate late phase trypsin-like gene expression in the midgut or ECD production by the ovaries. However, amino acids did enhance ILP3-mediated stimulation of trypsin-like gene expression and ECD production.Overall, our results indicate that ILPs from the brain synchronize blood meal digestion and amino acid availability with ovarian ECD production to maximize Vg expression by the fat body. The activation of digestion by ILPs may also underlie the growth promoting effects of insulin and TOR signaling in other species

The Neuropeptide Allatostatin A Regulates Metabolism and Feeding Decisions in Drosophila

Coordinating metabolism and feeding is important to avoid obesity and metabolic diseases, yet the underlying mechanisms, balancing nutrient intake and metabolic expenditure, are poorly understood. Several mechanisms controlling these processes are conserved in Drosophila, where homeostasis and energy mobilization are regulated by the glucagon-related adipokinetic hormone (AKH) and the Drosophila insulin-like peptides (DILPs). Here, we provide evidence that the Drosophila neuropeptide Allatostatin A (AstA) regulates AKH and DILP signaling. The AstA receptor gene, Dar-2, is expressed in both the insulin and AKH producing cells. Silencing of Dar-2 in these cells results in changes in gene expression and physiology associated with reduced DILP and AKH signaling and animals lacking AstA accumulate high lipid levels. This suggests that AstA is regulating the balance between DILP and AKH, believed to be important for the maintenance of nutrient homeostasis in response to changing ratios of dietary sugar and protein. Furthermore, AstA and Dar-2 are regulated differentially by dietary carbohydrates and protein and AstA-neuronal activity modulates feeding choices between these types of nutrients. Our results suggest that AstA is involved in assigning value to these nutrients to coordinate metabolic and feeding decisions, responses that are important to balance food intake according to metabolic needs