Principal Ideals in Ore Extensions

In this paper we prove that if R is a prime ring and I is an R-disjoint ideal of an Ore extension R[&#967;, &#948;,d], then I is closed and principal generated by a normal polynomial of minimal degree if and only if I contains a Sharma polynomial of minimal degree.</p

The influence of social value and selfcongruity on interpersonal connections in virtual social networks by Gen-Y tourists

This research focuses on the relationship of self-congruity and perceived social value with the interpersonal connections established by Generation Y tourists in virtual social networks. A quantitative study was performed using a sample of young travelers from Spain. The methodologies of Confirmatory Factor Analysis (CFA) and Structural Equation Models (SEM) were used to analyze the results. The findings of the research show that self-congruity influences the perceived social value; the perceived social value leads to satisfaction and the creation of interpersonal connections in virtual social networks; and the interpersonal connections in virtual social networks influence the use of these tools by Generation Y travelers

Can we improve the prediction of the influenza onset and save money in the process?

Each year, up to 650 000 people die of respiratory diseases linked to seasonal flu world-wide and billions of dollars are spent in preventing and mitigating its impact. Much of thissocial and economic burden could be prevented if the beginning of the Influenza outbreakwas timely known. This study predicts the outbreak’s commencement using a diverse rangeof data and then estimates the economic impact from a timely alarm of the outbreak’s ar-rival. Weekly maximum levels of precipitation along with fever and cough in the youngerpopulation were found among the most significant predictors of the onset

Precision Exercise Medicine: Sex Specific Differences in Immune and CNS Responses to Physical Activity

Physical activity is a powerful lifestyle factor capable of improving cognitive function, modifying the risk for dementia associated with neurodegeneration and possibly slowing neurodegenerative disease progression in both men and women. However, men and women show differences in the biological responses to physical activity and in the vulnerabilities to the onset, progression and outcome of neurodegenerative diseases, prompting the question of whether sex-specific regulatory mechanisms might differentially modulate the benefits of exercise on the brain. Mechanistic studies aimed to better understand how physical activity improves brain health and function suggest that the brain responds to physical exercise by overall reducing neuroinflammation and increasing neuroplasticity. Here, we review the emerging literature considering sex-specific differences in the immune system response to exercise as a potential mechanism by which physical activity affects the brain. Although the literature addressing sex differences in this light is limited, the initial findings suggest a potential influence of biological sex in the brain benefits of exercise, and lay out a scientific foundation to support very much needed studies investigating the potential effects of sex-differences on exercise neurobiology. Considering biological sex and sex-differences in the neurobiological hallmarks of exercise will help to enhance our understanding of the mechanisms by which physical activity benefits the brain and also improve the development of treatments and interventions for diseases of the central nervous system

A comprehensive multi-sector tool for analysis of Systemic Risk and Interconnectedness (SyRIN)

This paper presents the Systemic Risk and Interconnectedness (SyRIN) tool. SyRIN allows a comprehensive assessment of systemic risk via quantification of the impact of risk amplification mechanisms, due to interconnectedness structures across banks and other financial intermediaries-insurance, pension fund, hedge fund and investment fund sectors, which cannot be captured when analyzing sectors independently. The tool produces various metrics to evaluate systemic risk from complementary perspectives, including tail risk, cross-entity interconnectedness and the contribution to systemic risk by different entities and sectors. SyRIN is easily implementable with publicly available data and can be adapted to cater to different degrees of institutional granularity and data availability. The framework is designed to be a tool to identify vulnerabilities from a top-down perspective that can lead to deeper analysis in specific sectors for policy formulation

El gasto en salud de los hogares colombianos: un análisis descriptivo

From the Choice Theory we considered the way in which certain population characteristics affect the households health expenditure in Colombia. The approach of this paper is based on Deaton’s work (1980), where the choice set of the individuals is the intercession of the budgetary set and the consumption set. The analysis of the paths of the health expenditure for the Colombian households has a variance analysis approach taking data from the “Encuesta de Calidad de Vida de 1997 (ECV97)”. We fund that the households spend the 9,62% of their current income in health. The most important variables that explain the paths of the health expenditure are the geographic location; the social-economic level of the households; the affiliation’ type to the health system; the occupation and the educative level of the household head; and the epidemiologists characteristic of the households. ********************************************************************* A partir de la teoría de la elección se plantea la forma como ciertas características poblacionales afectan el gasto en salud de los hogares colombianos. El enfoque está basado en el trabajo de Deaton (1980), donde el conjunto de elección de los individuos es la intercesión del conjunto presupuestal y el conjunto de consumo. El análisis de los senderos de gasto en salud para los hogares colombianos utiliza un enfoque de análisis de varianza tomando datos de la Encuesta de Calidad de Vida de 1997 -ECV97. En general se encuentra que los hogares gastan el 9.62% de sus ingresos corrientes en salud, y que las variables más importantes para explicar el sendero de gasto son la ubicación geográfica; el estrato del hogar; el tipo de afiliación al sistema de salud, el tipo de ocupación y el nivel educativo del jefe del hogar; y las características epidemiológicas del hogar.análisis de varianza, gasto en salud, teoría de la elección

Fatores determinantes do rating soberano português

Tese de mestrado em Matemática Aplicada à Economia e Gestão, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2017O risco soberano é a probabilidade de uma entidade soberana incumprir as suas obrigações contratuais. Esta probabilidade é avaliada e calculada por diferentes agências de atribuição de rating, que têm em conta não só diferentes variáveis macroeconómicas, mas como outros fatores qualitativos. Cada uma das referidas agências utiliza diferentes estimativas e estimadores para atribuição de uma notação alfanumérica contida na categoria de investimento ou na categoria de notação especulativa. Este trabalho visa encontrar as variáveis determinantes para a atribuição do rating soberano no caso português nos últimos 21 anos (1996-2015) através de uma seleção inicial de variáveis tendo por base racional económico no caso português e a revisão bibliográfica. Maximizando a redução de situações de multicolinearidade através dos fatores da inflação da variância e a análise de componentes da variância e ainda aplicando os métodos de seleção de variáveis mais conhecidos - backwards, stepwise e forward linear - chegou-se à conclusão que os fatores determinantes são a variação do PIB (a preços constantes, base de 2011), a taxa Euribor, o endividamento de particulares, o rácio de Importações e Exportações sobre o PIB e ainda as Reservas Totais. Além disso, assegurou-se a qualidade da regressão com a validação da normalidade dos resíduos. Em seguida, foi estudada a influência do ciclo económico nos fatores determinados selecionados e chegou-se à conclusão que, além do reduzido significado estatístico devido à redução da amostra inicial, poucas são efetivamente significativas em cada uma das fases do ciclo económico. Por fim, estudou-se o efeito do rating no juro da dívida soberana portuguesa e chegou-se à conclusão que não se incorporavam as forças da procura do mercado nem os fatores qualitativos neste ajustamento, pelo que se decidiu replicar a mesma análise para um prémio de mercado, que consistiu na diferença entre o juro da dívida portuguesa e o juro da dívida alemã. Com efeito, concluiu-se que o rating era significativo na explicação do prémio de mercado, aliado dos três dos cinco fatores determinantes previamente selecionados, a variação do PIB, a taxa Euribor e ainda as Reservas Totais.The sovereign risk is the probability of a sovereign entity defaulting its contractual obligations. This probability is evaluated and calculated by different rating agencies considering macroeconomic variables and qualitative factors. Each of these agencies uses different estimation methodologies to attribute an alphanumeric grade that can range from “investment grade” to “speculative/non-investment grade”. This project aim is to find the determinant factors in the sovereign rating of the Portuguese Republic for the period between 1996 and 2015. After extensive literature review and some economic expert consultation, several initial variables, applicable to the Portuguese case, were set. To reach significant variables in determining the sovereign risk level, some mathematical methods were used, including multicollinearity cleansing (through VIF and ACV) and variable selection methods (backwards, stepwise, linear forward). These processes led to the selection of the following variables: “GDP variation (constant prices, 2011)”, “Euribor”, “Private Indebtedness”, “(Imports+Exports)/GDP” and “Total Reserves”. In addition, the regression quality was verified by the normal distribution of the residuals. Afterwards, the influence of the economic cycle on the selected determinants was studied. Few of the selected variables seem to be statistically significant in each of the economic cycle phases. However, the low statistical significance of this study, due to the reduction of the initial sample, should be considered. Finally, the effect of the rating on Portuguese sovereign debt interest was studied and it was concluded that neither the demand forces of market nor the qualitative factors in this adjustment were incorporated. To fix this issue, an analysis of the premium market between Portuguese and German debt interest was conducted. Everything considered, it was concluded that the rating was significant in explaining the market premium, together with three of the five variables previously selected: the GDP variation, the Euribor rate and the Total Reserves