On the Evolution of Stars that Form Electron-degenerate Cores Processed by Carbon Burning. V. Shell Convection Sustained by Helium Burning, Transient Neon Burning, Dredge-out, Urca Cooling, and Other Properties of an 11 M? Population I Model Star

A stellar model of mass 11 M☉ and Population I composition is evolved from the hydrogen-burning main sequence through the core carbon-burning phase. In contrast with 9, 10, and 10.5 M☉ models studied in earlier papers of this series, carbon burning is ignited at the center of the 11 M☉ model. Like the 10.5 M☉ model, the 11 M☉ model experiences a dredge-out episode at the end of the carbon-burning phase. At the beginning of this episode, a semiconvective zone forms at the base of the hydrogen-rich envelope and carries hydrogen inward in mass toward the outer edge of a fully convective zone that is sustained by helium burning at its base. Hydrogen diffuses into the helium-rich convective zone untila hydrogen shell flash occurs. Helium burning dies out and the outer edge of the convective layer,sustained by fluxes due to hydrogen burning, extends outward in mass through hydrogen-rich material, mixing freshly synthesized nuclei outward. Then, hydrogen burning dies out and the outer edge of the convective shell, now sustained primarily by fluxes due to the release of gravothermal energy, moves outward until it reaches the inner edge of the convective envelope. Freshly synthesized material is then convected to the surface. Mixing during the final phase of homogenization in the convective envelope is maintained by fluxes due to the release of gravothermal energy. At the end of the dredge-out phase, the surface nitrogen abundance has decreased and the C/N ratio has changed from less than unity to larger than unity, showing that mixing has extended into regions where helium burning has manufactured substantial quantities of 12C and destroyed 14N. Prior to the dredge-out phase, neon burning is narrowly averted, and, after the dredge-out phase, neutrino losses due to electron capture and decay reactions between A=25 and A=23 isotopes in and above convective Urca shells cool the inner portions of the electron-degenerate oxygen-neon (ONe) core. Ultimately, the model becomes a thermally pulsing super-asymptotic giant branch (TPSAGB) star with an ONe core of mass ~1.368 M☉. Hydrogen and helium burning over a period of ~1.4×104 yr of TPSAGB evolution add a carbon-oxygen layer of mass ~0.014 M☉ to the electron-degenerate core. Then, electron captures on products of carbon burning lead to the collapse of the core into a neutron star and expulsion of the envelope in a weak Type II supernova explosion. The ratio of helium to hydrogen in the ejecta is approximately twice solar

Corporate impact investing: a new paradigm for csr?

This paper sets out the case for the use of impact investing as part of companies’ CSR strategy, demonstrated by the term “corporate impact investing” or “corporate impact venturing”. After an indirect analysis of global practices in corporate impact investment, it considers whether companies are interested in employing this innovative practice in their CSR strategy and how they could be incentivized to do so through direct research methods, with a focus on Europe. A survey answered by 116 company representatives reveals that companies are interested in impact investing yet the majority was not initially aware of its existence; therefore if the right incentives are put into place a new paradigm for CSR may aris

Algorithms and Hardness for Multidimensional Range Updates and Queries

Traditional orthogonal range problems allow queries over a static set of points, each with some value. Dynamic variants allow points to be added or removed, one at a time. To support more powerful updates, we introduce the Grid Range class of data structure problems over arbitrarily large integer arrays in one or more dimensions. These problems allow range updates (such as filling all points in a range with a constant) and queries (such as finding the sum or maximum of values in a range). In this work, we consider these operations along with updates that replace each point in a range with the minimum, maximum, or sum of its existing value, and a constant. In one dimension, it is known that segment trees can be leveraged to facilitate any n of these operations in O?(n) time overall. Other than a few specific cases, until now, higher dimensional variants have been largely unexplored. Despite their tightly-knit complexity in one dimension, we show that variants induced by subsets of these operations exhibit polynomial separation in two dimensions. In particular, no truly subquadratic time algorithm can support certain pairs of these updates simultaneously without falsifying several popular conjectures. On the positive side, we show that truly subquadratic algorithms can be obtained for variants induced by other subsets. We provide two general approaches to designing such algorithms that can be generalised to online and higher dimensional settings. First, we give almost-tight O?(n^{3/2}) time algorithms for single-update variants where the update and query operations meet a set of natural conditions. Second, for other variants, we provide a general framework for reducing to instances with a special geometry. Using this, we show that O(m^{3/2-?}) time algorithms for counting paths and walks of length 2 and 3 between vertex pairs in sparse graphs imply truly subquadratic data structures for certain variants; to this end, we give an O?(m^{(4?-1)/(2?+1)}) = O(m^1.478) time algorithm for counting simple 3-paths between vertex pairs

Dinámica de la infección de sp. (Digenea: Diplostomidae) en el primer y segundo hospedador intermediario de un lago Andino Patagónico (Argentina)

In Argentinean Patagonia, a species of the genus Posthodiplostomum has been reported infectingpopulations of the snail Anisancylus obliquus and the galaxiid fi sh Galaxias maculatus (small puyen), meanwhileadults would develop in piscivorous birds. The aim of the present work was to describe the seasonal dynamicsof this parasite in the intermediate hosts inhabiting a small, shallow Patagonian Andean lake. Samples ofsnails and fi sh from Patagua Lake (40° 46? S - 71º 36? W) were collected monthly from October 2010 to March2011. The larval infection of Posthodiplostomum sp. increases in spring. Snails were infected from Novemberto January, with the highest prevalence in December (8.2%), decreasing in January (3.1%). In fi sh, prevalenceranged between 70% (November) and 100% (December to March). The highest infection values were recordedin larger fi sh, while the small fi sh with sizes less than 40 mm exhibited low infection levels. So, we can infer thatthe life cycle of Posthodiplostomum sp. in Patagonia shows a seasonal pattern, with larval development duringspring, when cercariae emerge from larger snails, resulting in a higher prevalence of fi sh in the littoral.Fil: Ritossa, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Flores, Verónica Roxana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Viozzi, Gustavo Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue; Argentin

Fair Allocation of Two Types of Chores

We consider the problem of fair allocation of indivisible chores under additive valuations. We assume that the chores are divided into two types and under this scenario, we present several results. Our first result is a new characterization of Pareto optimal allocations in our setting, and a polynomial-time algorithm to compute an envy-free up to one item (EF1) and Pareto optimal allocation. We then turn to the question of whether we can achieve a stronger fairness concept called envy-free up any item (EFX). We present a polynomial-time algorithm that returns an EFX allocation. Finally, we show that for our setting, it can be checked in polynomial time whether an envy-free allocation exists or not

Contribution à l'étude de certains paramètres physiques d'un sol volcanique induré (cangahua) réhabilité

En el medio agropecuario ecuatoriano, la cangahua (formacion procedente de las cenizas volcanicas endurecidas) ocupa amplias areas donde el desarrollo de todos los cultivos se ve limitado por la insuficiente fertilidad y la fuerte sensibilidad a la erosion, que caracterizan este tipo de suelo. Con en fin de aumentar la superficie agraria util y en general de garantizar un correcto manejo del recurso suelo, se han establecido algunos programas de rehabilitacion de la cangahua. Este trabajo intenta responder a la exigencia de evaluacion de los efectos de los tratamientos agronomicos sobre las cualidades fisicas y quimicas de la cangahua recuperada. El objetivo era mejorar la fertilidad del suelo a traves de la incorporacion de abonos y por otro lado incrementar la resistencia a la erosion mediante el aporte de material organico que estabilice la estructura del suelo y pueda garantizar una productividad a largo plazo. Los resultados en cuanto a las caracteristicas hidrodinamicas del suelo, obtenidos mediante la utilizacion de un simulador de lluvia, las observaciones de campo y los analisis de laboratorio han mostrado que desde el punto de vista agronomico, el tratamiento por abonos organicos, junto con una preparacion tosca del suelo constituye el mejor, en terminos de abastecimiento de agua, de estabilidad estructural y de rendimiento a largo plazo de los cultivos. (Résumé d'auteur

A internacionalizaçăo de cooperativas agropecuarias : um estudo multi-metodo das cooperativas agropecuarias do estado do Parana /

Orientador : Prof. Dr. Sergio BulgacovDissertaçăo (mestrado) - Universidade Federal do Paraná, Setor de Cięncias Sociais Aplicadas, Programa de Pós-Graduaçăo em Administraçăo. Defesa: Curitiba, 2008Inclui bibliografiaÁrea de concentraçăo: Estratégia e analise organizaciona

On the formation of oxygen-neon white dwarfs in close binary systems

The evolution of a star of initial mass 10 $M_{\odot}$, and metallicity $Z = 0.02$ in a Close Binary System (CBS) is followed from its main sequence until an ONe degenerate remnant forms. Restrictions have been made on the characteristics of the companion as well as on the initial orbital parameters in order to avoid the occurrence of reversal mass transfer before carbon is ignited in the core. The system undergoes three mass loss episodes. The first and second ones are a consequence of a case B Roche lobe overflow. During the third mass loss episode stellar winds may play a role comparable to, or even more important than Roche lobe overflow. In this paper, we extend the previously existing calculations of stars of intermediate mass belonging to close binary systems by following carefully the carbon burning phase of the primary component. We also propose different possible outcomes for our scenario and discuss the relevance of our findings. In particular, our main result is that the resulting white dwarf component of mass $1.1 M_\odot$ more likely has a core composed of oxygen and neon, surrounded by a mantle of carbon-oxygen rich material. The average abundances of the oxygen-neon rich core are $X({\rm O}^{16})=0.55$, $X({\rm Ne}^{20})=0.28$, $X({\rm Na}^{23})=0.06$ and $X({\rm Mg}^{24})=0.05$. This result has important consequences for the Accretion Induced Collapse scenario. The average abundances of the carbon-oxygen rich mantle are $X({\rm O}^{16})=0.55$, and $X({\rm C}^{12})=0.43$. The existence of this mantle could also play a significant role in our understanding of cataclysmic variables.Comment: 13 pages, 12 figures, accepted for publication in A&

Cooperativas agropecuárias : um quadro de referência para análise e descrição do envolvimento das cooperativas agropecuárias brasileiras com mercados internacionais

Orientador : Prof. Dr.Ritossa, Claudia MonicaTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Sociais Aplicadas, Programa de Pós-Graduação em Administração. Defesa: Curitiba, 02/03/2012Bibliografia: fls. 147-154Resumo: O número de cooperativas, cooperados e funcionários vem crescendo regularmente no ramo agropecuário do cooperativismo brasileiro, porém, as organizações deste segmento parecem não estarem orientadas para a escolha estratégica de internacionalização. Apenas 160 delas participaram de atividades de exportação do total de 1.615 cooperativas agropecuárias em 2009. Para identificar o que restringe esta atividade, este estudo seccional, realizado ex post facto, pretendeu descrever o envolvimento das cooperativas agropecuárias brasileiras com mercados internacionais sob a perspectiva de suas condições internas. Para tanto, um quadro de referência, contando com quatro tipologias de análise aplicadas às cooperativas internacionalizadas ou não, foi proposto. A revisão de literatura abordou os fundamentos do cooperativismo, diferentes maneiras de ser" uma cooperativa e teorias relacionadas à internacionalização destes empreendimentos. A pesquisa foi levada a efeito mediante o uso de metodologia quantitativa, com técnicas múltiplas de coleta de dados aplicadas em duas etapas distintas. Na primeira, foi utilizada a pesquisa documental para buscar dados e indicadores que pudessem auxiliar no estabelecimento da amostragem da etapa investigativa seguinte. Na segunda, foi aplicado levantamento tipo survey interseccional, com questionário estruturado e perguntas predominantemente fechadas para serem mensuradas em uma escala de cinco pontos do tipo Likert. Análises estatísticas descritivas e o modelo de Regressão Linear Múltipla foram empregadas no tratamento dos dados secundários. Os dados coletados em 138 questionários válidos, além das análises descritivas, receberam os testes One-Way Anova, as correlações bivariadas de Person, Spearman e Kendall e o teste do Chi-quadrado. Os principais achados indicam que: a) a relação de dependência entre os construtos condições internas e envolvimento com mercados internacionais se demonstrou válida; b) é possível estabelecer um quadro de referência que contemple tipologias para todas as cooperativas agropecuárias brasileiras, internacionalizadas ou não; c) as cooperativas empreendedoras são as únicas a apresentarem assiduidade na comercialização internacional; d) as cooperativas conservadoras adotam estratégias mais cautelosas e priorizam a comercialização doméstica; e) as cooperativas reativas apresentam graves problemas relacionados com suas condições internas; f) as cooperativas desestruturadas não estão envolvidas com mercados internacionais; g) as cooperativas têm seu faturamento ampliado ao adotarem estratégias de diferenciação e internacionalização, mas também ao concentrarem suas atividades no setor de carnes; h) a gestão profissionalizada e dedicada em tempo integral promove o aumento da competitividade da cooperativa em mercados internacionais, a disposição dos associados em investir em oportunidades de crescimento e a regularidade exportadora; i) as tipologias apresentam diferença estatística significativa em sua atitude estratégica; e, j) as tipologias apresentam diferença estatística significativa nas matrizes de negócios selecionadas.Abstract: The number of cooperatives, cooperative members and employees has been steadily increasing in the field of agricultural cooperatives in Brazil, however, organizations of this field do not seem to be geared to the strategic choice of internationalization. In 2009, only 160 of them participated in export activities of the total of 1615 agricultural cooperatives. To identify what could be restricting this activity, this cross-sectional study, conducted ex post facto, intended to describe the involvement of Brazilian agricultural cooperatives in international markets from the perspective of their internal conditions. Accordingly, a frame of reference, with four types of analysis applied to cooperatives, internationalized or not, was proposed. The literature review addressed the fundamentals of cooperatives, different ways to "be" a cooperative and theories related to the internationalization of this organizations. The research was carried out through the use of quantitative methodology and multiple techniques of data collection, which were applied in two steps. At first it was used documentary research to obtain data and indicators that could assist in the establishment of the sample necessary for the following investigative step. The second one consisted in an inter-sectional survey, by the application of a structured questionnaire with predominantly closed questions to be measured on a five-point Likert-type scale. Descriptive statistics and multiple linear regression models were used on the analysis of the secondary data. The data collected on 138 valid questionnaires, in addition to descriptive analyzes, they received the one-way ANOVA test, Person’s, Spearman’s and Kendall’s bivariate correlations and the Chi-square test. The main findings indicate that: a) the dependence between the constructs internal conditions and involvement in international markets has been shown valid, b) the entrepreneurial cooperatives are the only one to relate to international markets on a permanent basis, c) the conservative cooperatives adopt more cautious strategies and prioritize the domestic market, d) reactive cooperatives have severe problems with their internal conditions; e) unstructured cooperatives are not involved with international markets, f) cooperatives have their revenues xpanded by adopting differentiation and internationalization strategies, but also in concentrating their activities in the meat industry, g) professional managers with full time dedication to the post promote increased competitiveness of the cooperative in international markets, the willingness of members to invest in growth opportunities and frequent internationalization activities, h) the typologies have statistically significant differences in their strategic approach, and, i) the typologies have statistically significant differences in the industries which they select to operate