Financial contagion through space-time point processes

Statistical Methods & Applications - We propose to study the dynamics of financial contagion by means of a class of point process models employed in the modeling of seismic contagion. The...     

Geospatial Modeling of Containment Probability for Escaped Wildfires in a Mediterranean Region

Despite escalating expenditures in firefighting, extreme fire events continue to pose a major threat to ecosystem services and human communities in Mediterranean areas. Developing a safe and effective fire response is paramount to efficiently restrict fire spread, reduce negative effects to natural values, prevent residential housing losses, and avoid causalties. Though current fire policies in most countries demand full suppression, few studies have attempted to identify the strategic locations where firefighting efforts would likely contain catastrophic fire events. The success in containing those fires that escape initial attack is determined by diverse structural factors such as ground accessibility, airborne support, barriers to surface fire spread, and vegetation impedance. In this study, we predicted the success in fire containment across Catalonia (northeastern Spain) using a model generated with random forest from detailed geospatial data and a set of 73 fire perimeters for the period 2008–2016. The model attained a high predictive performance (AUC = 0.88), and the results were provided at fine resolution (25 m) for the entire study area (32,108 km²). The highest success rates were found in agricultural plains along the nonburnable barriers such as major road corridors and largest rivers. Low levels of containment likelihood were predicted for dense forest lands and steep-relief mountainous areas. The results can assist in suppression resource pre-positioning and extended attack decision making, but also in strategic fuels management oriented at creating defensive locations and fragmenting the landscape in operational firefighting areas. Our modeling workflow and methods may serve as a baseline to generate locally adapted models in fire-prone areas elsewhere.     

Implicit cover inequalities

In this paper we consider combinatorial optimization problems whose feasible sets are simultaneously restricted by a binary knapsack constraint and a cardinality constraint imposing the exact number of selected variables. In particular, such sets arise when the feasible set corresponds to the bases of a matroid with a side knapsack constraint, for instance the weighted spanning tree problem and the multiple choice knapsack problem. We introduce the family of implicit cover inequalities which generalize the well-known cover inequalities for such feasible sets and discuss the lifting of the implicit cover inequalities. A computational study for the weighted spanning tree problem is reported.     

Opting in to Opt out? Emigration and Group Participation in Albania

The objective of this paper is to determine whether the participation in social organizations represents a complement or a substitute with respect to international emigration. To address this research question, an instrumental variable approach is used, as group participation and international migration are potentially jointly determined. This is the case if the family considers emigration and group participation as alternative strategies to cope with uncertainty or a liquidity need, or alternatively when the family decides to invest in group participation in order to gain information helpful to emigrate. The results of the empirical estimation reveal that families participating in social organizations are more likely to migrate internationally and therefore social networks act as a complement for emigration. This may indicate that families recourse to social networks in order to collect important information that facilitates international migration.     

Comfort in English and Swedish country houses,c.1760–1820

Comfort as an idea and ideal has attracted growing interest, especially in an Anglo-American context. Much of the discussion has centred either on improvements in physical comfort, not least through new technologies, or on emotional comfort and the social construction of the home. This article brings together these ideas in a comparative analysis of English and Swedish landowners. It draws on a range of correspondence to uncover more about the ways in which members of the elite themselves conceived and achieved comfort in very different geographical, economic and cultural contexts. Whilst ‘English comfort’ became widespread as an idealization of elite lifestyles by the early nineteenth century, both in Sweden and elsewhere, we argue that many of its social and physical imperatives were commonplace much earlier. This involved shared concerns with warmth and airiness, and the ways in which these were linked to health and well-being, but also with the construction of appropriate social settings. Yet, it was the emotional and non-material dimensions of comfort that dominated the correspondence in both countries: a concern with family and with home as a place defined by relationships with people rather than things.     

The influence of corporate governance on changes in risk following the global financial crisis: evidence from the Portuguese stock market

This paper examines the influence of corporate governance characteristics on changes in total, market and idiosyncratic risk in the Portuguese capital market following the collapse of Lehman Brothers. We aim to address corporate practices, while determining if corporate governance characteristics can help predict future variations of the risk associated with a certain security and, in this sense, if these characteristics may be used to help monitor or forecast risk of an existing portfolio of securities over time. We find positive and significant changes in total and idiosyncratic risk for non-financial firms listed on Euronext Lisbon, consistent with increases in investor uncertainty during the crisis period. Our results suggest that changes in risk measures over a shorter-term and a longer-term period vary with governance characteristics. The capital market rewarded companies with a greater proportion of non-executive directors and directors that exercise (on average) management roles in more companies or institutions. On the other hand, the capital market punished companies with a greater proportion of independent directors and greater ownership concentration.     

Life-Satisfaction, Values and Goal Achievement: The Case of Planned Versus by Chance Searches on the Internet

The relation between life domains satisfactionand overall life satisfaction, values,internal/external perceived control and theoption of planning or by chance searchinginformation on the Internet has been exploredin a sample of Spanish adolescents aged 12 to16 (N=968). Age and sex differences have beenexamined. Results clearly confirm a positiverelation between satisfaction with life domainsand overall satisfaction with life.Satisfaction with life as a whole shows also tobe positively correlated with non-materialisticvalues. Perceived control shows to be, onceagain, a key construct to understand bothlife-satisfaction of adolescents and theirbehavioural intentions to plan or not to plantheir action to fulfil intended goals. A clearpattern between external and internal perceivedcontrol stems from our analysis: subjectsreporting to rely on chance when searchinginformation show higher external perceivedcontrol while respondents who prefer to planshow higher internal perceived control. Themore satisfaction expressed with learningrelated items (satisfaction with schoolperformance, learning, and preparation forfuture), with family and with life as a whole,the more tendencies are observed among therespondents to plan their search. No directrelation has been observed between values andbehavioural intentions to plan or not to planaction to fulfil intended goals. Perceivedcontrol, but also satisfaction with some lifedomains and with life as a whole seem to act asmediating factors between behaviouralintentions and values.     

The Subjective Well-being of Adolescents from Two Different Cultures: Applying Three Versions of the PWI in Algeria and Spain

This paper analyses the crosscultural comparability of well-being among 13–20 year-old adolescents using two samples, one from Oran County (Wilaya) in Algeria and another from Catalonia (Spain). The following are used as well-being indicators: a modified version of the original Personal Well-being Index (PWI) (Cummins et al. in Soc Indicat Res 64:159–190, 2003b), a single-item scale on overall life satisfaction (OLS) and a list of complementary items on satisfaction with various life domains. This research tests the original version of the PWI with some changes and two other versions with additional items. Confirmatory factor analyses show good fit statistics for the three versions with the pooled sample of adolescents from the two countries. The multigroup models show that correlations and regressions may be compared between the two samples, but not means, probably due to different cultural response styles among adolescents in the two countries. Structural equation models including OLS also show good fit statistics. When gender and age are included in these models, the former does not show any correlation with PWI11 in either of the two countries, whereas age shows a clearly negative correlation in both. A new version of the PWI with 11 items has shown higher standardized regression coefficients when the items are regressed on OLS and higher R² and each of the items has shown to contribute with unique explained variance using the pooled sample, although 3 of the original scale items do not show a significant contribution in Algeria. The fact that a multigroup model using this 11-item version shows good fit with constrained loadings when comparing samples from such different cultural and linguistic contexts as Catalonia and Algeria offers new opportunities for international comparative research of adolescents’ subjective well-being.     

Cross-Cultural Adaptation,Validity and Reliability of the Escala Pessoal de Resultados

The present article aims to examine the validity and reliability of the Portuguese version of Personal Outcomes Scale the Escala Pessoal de Resultados (EPR). This scale represents an instrument to measure the quality of life (QOL) in people with intellectual disabilities (ID). The study was initiated with the application of international guidelines in cross-cultural adaptation, culminating with an evaluation of 10 experts for the quantitative evidence of the content validity. All EPR’s items were considered relevant and there was a moderated agreement (k > .40) among the experts in the calculation of Cohen’s kappa, finding some coefficients’ that are considered as an excellent agreement (k > .75). In test field, our sample comprised 335 adults with ID on level of intermittent and limited support needs, even as the respective proxies. The scale showed an excellent internal consistency (α = .94). EPR’s construct validity indexes are also reported and discussed. The study provides EPR as a valid instrument for assess the QOL in ID field, and the scale seems to be useful for improvement of Portuguese rehabilitation practices and services.     

Leafy spanning k-forests

Journal of Combinatorial Optimization - We denote by Leafy  Spanning $$k$$ -Forest the problem of, given a positive integer k and a graph G with at most k components,...