Parametric estimation for ARFIMA models via spectral methods

Given a fractional integrated, autoregressive, moving average,ARFIMA (p, d, q) process, the simultaneous estimation of the short and long memory parameters can be achieved by maximum likelihood estimators. In this paper, following a two-step algorithm, the coefficients are estimated combining the maximum likelihood estimators with the general orthogonal decomposition of stochastic processes. In particular, the principal component analysis of stochastic processes is exploited to estimate the short memory parameters, which are plugged into the maximum likelihood function to obtain the fractional differencingd.     

When friendship is stronger than prejudice. Role of intergroup friendships among adolescents in two distinct socio-cultural contexts of immigration

Despite the structural characteristics of international migration in most European countries, the persistence of prejudice and negative attitudes towards immigrants represents an unsolved problem that erodes social cohesion. European institutions continue to be concerned about the spread of xenophobia, especially among young generations. This article aims to shed light on the crucial role of intergroup friendships, considered a key factor in reducing the hostility toward immigrant groups. In particular, the aim is to verify the effects of intergroup friendships on prejudice, using data derived from an international survey carried out in France and Italy, two emblematic European countries as regarding the experience of international migration. 1,642 French and Italian adolescents, selected by a rationale choice sample, were involved: multivariate analysis confirmed the hypothesis that adolescents who hold intergroup friendships show lower levels of prejudice. The influence of the intergroup friendships on the decrease of intolerance is evident especially on socioeconomic and security issues while for the identity matters its effects are moderated by the country of residence of the participants. Considering these results, positive contacts among local and immigrant populations are recommended in order to reduce social fragmentation and foster social cohesion.     

Can antenatal classes reduce the rate of cesarean section in southern Italy?

Background

Among European Countries, Italy has the highest rate of cesarean section (36.8%), and in the Campania region this rate reaches 60.0%.

An emotional step toward automated trust detection in crisis social media

To this date, research on crisis informatics has focused on the detection of trust in Twitter data through the use of message structure, sentiment, propagation and author. Little research has examined the usefulness of these messages in the crisis response domain. In this paper, we characterize tweets, which are perceived useful or trustworthy, and determine their main features as one possible dimension to identify useful messages in case of crisis. In addition, we examine perceived emotions of these messages and how the different emotions affect the perceived usefulness and trustworthiness. Our analysis is carried out on two datasets gathered from Twitter concerning Hurricane Sandy in 2012 and the Boston Bombings in 2013. The results indicate that there is a high correlation between trustworthiness and usefulness, and, interestingly, that there is a significant difference in the perceived emotions that contribute to each of these. Our findings are poised to impact how messages from social media data are analyzed for use in crisis response.     

Folate: a possible role in erectile dysfunction?

A growing body of evidence suggests a role for homocysteine (Hcys) and folate (FA) in erectile function (EF): Hcys appears to impair EF affecting endothelium via several mechanism whereas the role of FA remains to be elucidated, besides decreasing Hcys. To assess correlation between erectile dysfunction (ED) and serum levels of FA, Hcys, and B12, we enrolled 31 patients affected by ED (Group A; age 52.83?±?11.89 years) and 31 healthy adults (Group B; age 49.14?±?13.63 years). Fasting blood samples were taken for each subject. ED was assessed by the International Index of Erectile Function-5 (IIEF-5). IIEF-5 mean score was significantly lower in Group A than in Group B (10.71?±?4.24 versus 23.32?±?1.33, p?p?p?相似文献   

R&D (Re)location and Offshore Outsourcing: A Management Perspective

The paper reviews and systematizes the management literature directly and indirectly related to (re)location of research and development (R&D), in the form of both insourcing and outsourcing. The focus in particular is on R&D offshore outsourcing and its main drivers, including locational constraints and opportunities, motives, strategic decisions and managerial challenges. The analysis synthesizes and links the main propositions and findings of the theoretical and empirical work to build an original management and strategy centred framework which looks at R&D (re)location from a client–vendor perspective. In this case, the client is the offshoring company, and the vendors are the firms located in the host country. The characteristics of the firms and locations considered vis‐à‐vis the offshoring firm's goals are examined, the strategies implemented, the management and organizational challenges that R&D offshore outsourcing entails, and the ways in which offshoring impacts on both home and host locations are investigated.