Inapproximability results for the lateral gene transfer problem

This paper concerns the Lateral Gene Transfer Problem. This minimization problem, defined by Hallett and Lagergren (2001), is that of finding the most parsimonious lateral gene transfer scenario for a given pair of gene and species trees. Our main results are the following:

Equality of Educational Opportunities,Schools’ Characteristics and Resilient Students: An Empirical Study of EU-15 Countries Using OECD-PISA 2009 Data

In the existent literature, little attention has been paid to the characteristics of the schools attended by the “resilient” students, i.e. those that, despite their socioeconomic background, are able to obtain high academic results. The paper explores this topic by using OECD-PISA 2009 data for EU-15 countries; we estimate a statistical model to find those school-level variables that are correlated with the probability of a disadvantaged student being resilient, net of country-specific structural differences. A by-product of the study is a better understanding of the educational drivers that help disadvantaged students and this can be beneficial for a country’s educational system as a whole. In particular, the analysis reveals that schools attended by resilient students do offer more extracurricular activities and are characterized by a better positive school climate.     

Entry and Exit Strategies in Migration Dynamics

In this paper, we use a real option framework in order to study the role of combined entry and exit strategies in migration. The paper’s aim consists in investigating migrants’ behaviour and in particular their duration of stay in the host country. Our framework shows two threshold levels: the first triggers the migration choice, while the second triggers the return to the country of origin. The difference between these two thresholds defines a region of inaction (hysteresis) i.e. the length of the immigrant’s stay in the host country (duration). Our theoretical results show that: (a) the phenomenon of hysteresis is amplified by ethnic communities both in entry and in exit cases; and (b) migration policies that attempt to exacerbate entry could increase duration of immigrants and the migration stock in the host country. Furthermore, the community could reduce the minimum wage level required to trigger both exit and entry. This fact could explain why we sometimes see migration inflows with a low wage differential and also with underemployment.     

Healthy, educated and wealthy: A primer on the impact of public and private welfare expenditures on economic growth

In this paper, we provide first evidence of the impact of public and private expenditures in health and education on economic growth, via their influence on people's health, skills and knowledge. We consider a growth accounting framework in order to test whether countries that devote a larger amount of resources to the consumption of health and educational services experience higher growth rates. We also test whether the effects on economic growth of public expenditure in health and education differ from those of private expenditure. Our empirical analysis is based on a panel of 19 OECD countries observed between 1971 and 1998. The results are consistent with the hypothesis that health and education expenditure affects positively growth. The estimated impact is stronger for health than for education. More importantly, we find some evidence that public expenditure influences GDP growth more than private expenditure.     

The influence of the elites’ discourse in political attitudes: evidence from the Basque Country

Do parties’ position shifts matter for public opinion? In this paper, we would like to compare the discourses of the Basque elites with the Basque public opinion regarding the reinforcement of the Autonomy. So, combining content analysis methodology and survey data we aim to test if a mainstream political party (specifically, the Basque Nationalist Party [Partido Nacionalista Vasco]) cause the public view to shift on one of the most important policy issues in the Basque Country, that is, the territorial dimension. This study validates the top-down model and concludes that elite political discourses actually affect popular opinion.     

Influence of substrate depth and vegetation type on temperature and water runoff mitigation by extensive green roofs: shrubs versus herbaceous plants

The relative contribution of substrate depth and vegetation type on temperature mitigation and stormwater runoff reduction was studied in an experimental green roof in North eastern Italy. Two substrate depths (120 and 200?mm) and two vegetation types (herbaceous plants and shrubs, respectively) were used, and compared to control modules with similar substrate depths but left bare of vegetation. Experimental observations showed that: a) green roofs substantially reduce thermal load over the rooftop, with significant effects of substrate depth and no apparent impact of vegetation type; b) thermal effects are strongly influenced by substrate water content; c) green roofs strongly reduce water runoff with significant substrate x vegetation effects. Our data suggest that green roof design addressed to optimization of the thermal functions should take into account adequate planning of substrate depth. Moreover, our data show that vegetated modules out-competed medium-only ones in terms of runoff reduction capacity, in accordance with some previous studies. Both shrub-vegetated and herbaceous modules intercepted and stored more than 90% rainfall during intense precipitation events, with no significant difference between the two vegetation types despite different substrate depths.     

Micro-Flexibility and Macro-Rigidity: Some Notes on Expectations and the Dynamics of Aggregate Supply

ABSTRACT: The high macro supply elasticity experienced by industrialised countries during the second post-war boom is not explainable as the aggregate effect of current variations of companies’output in response to current variations of demand. A firm cannot adapt rapidly its output to higher demand unless it has decided fairly in advance to expand its productive capacity. Macro elasticity depends thus on the existence of ex ante excess capacity, built on the basis of expectations. The post-war boom is thus explained in terms of a virtuous sequence expectations-decisions-events. This approach helps in understanding the inversion of the expansionary phase to one of stag-flation, the failure of Keynesian policies and the subsequent industrial restructuring which gave rise to the present employment squeeze. Flexibility is something which depends on the relationships between individual expectations and decisions and their systemic results; the presently pursued micro-flexibility is at high risk of producing increasing macro-rigidity.     

Sense of Community and the Perception of the Socio-Physical Environment: A Comparison Between Urban Centers of Different Sizes Across Europe

Measures of subjective well-being, and especially life evaluations, or judgments about how happy people are with their lives as a whole, enrich and empower social indicators research. They do this by requiring other social indicators as explanatory variables and providing a coherent encompassing framework within which the relative importance of other social indicators can be established.