Information Mobility: Information Dissemination in Mobile Networks

En el nostre projecte, considerem un escenari urbà o interurbà on persones amb dispositius mòbils (smartphones) o vehicles equipats amb interfícies de comunicació, estan interessats en compartir fitxers entre ells o descarregar-los al creuar Punts d’Accés (APs) propers a la carretera. Estudiem la possibilitat d’utilizar la cooperació en les trobades casuals entre nodes per augmentar la velocitat de descàrrega global. Amb aquest objectiu, plantejem algoritmes per a la selecció de quins paquets, per a quins destins i quins transportistes s’escullen en cada moment. Mitjançant extenses simulacions, mostrem com les cooperacions carry&forward dels nodes augmenten significativament la velocitat de descàrrega dels usuaris, i com aquest resultat es manté per a diversos patrons de mobilitat, col•locacions d'AP i càrregues de la xarxa. Per altra banda, aparells com els smartphones, on la targeta de WiFi està encesa contínuament, consumeixen l'energia de la bateria en poques hores. En molts escenaris, una targeta WiFi sempre activa és poc útil, perque sovint no hi ha necessitat de transmissió o recepció. Aquest fet es veu agreujat en les Delay Tolerant Networks (DTN), on els nodes intercanvien dades quan es creuen i en tenen l’oportunitat. Les tècniques de gestió de l’estalvi d’energia permeten extendre la duració de les bateries. El nostre projecte analitza els avantatges i inconvenients que apareixen quan els nodes apaguen períodicament la seva targeta wireless per a estalviar energia en escenaris DTN. Els nostres resultats mostren les condicions en que un node pot desconnectar la bateria sense afectar la probabilitat de contacte amb altres nodes, i les condicions en que aquesta disminueix. Per exemple, es demostra que la vida del node pot ser duplicada mantenint la probabilitat de contacte a 1. I que aquesta disminueix ràpidament en intentar augmentar més la vida útil.

Conformations of poly{G}-poly{C} π stacks with high hole mobility

Charge transfer properties of DNA depend strongly on the π stack conformation. In the present paper, we identify conformations of homogeneous poly-{G}-poly-{C} stacks that should exhibit high charge mobility. Two different computational approaches were applied. First, we calculated the electronic coupling squared, V2, between adjacent base pairs for all 1 ps snapshots extracted from 15 ns molecular dynamics trajectory of the duplex G15. The average value of the coupling squared 〈 V2 〉 is found to be 0.0065 eV2. Then we analyze the base-pair and step parameters of the configurations in which V2 is at least an order of magnitude larger than 〈 V2 〉. To obtain more consistent data, ∼65 000 configurations of the (G:C)2 stack were built using systematic screening of the step parameters shift, slide, and twist. We show that undertwisted structures (twist<20°) are of special interest, because the π stack conformations with strong electronic couplings are found for a wide range of slide and shift. Although effective hole transfer can also occur in configurations with twist=30° and 35°, large mutual displacements of neighboring base pairs are required for that. Overtwisted conformation (twist38°) seems to be of limited interest in the context of effective hole transfer. The results may be helpful in the search for DNA based elements for nanoelectronics

Economic crisis and recovery: changes in second birth rates within occupational classes and educational groups

This study assesses the decline in second birth rates for men and women across different skill levels in transitional Russia. Changes within educational groups and occupational classes are observed over three distinct time periods: the Soviet era, economic crisis, and economic recovery. The most remarkable finding is the similarity in the extent second birth rates declined within educational groups and occupational classes during the economic crisis. Although further decline occurred in the recovery period, more variation emerged across groups.

Do women in female-dominated occupations exit the labour market more? Evidence from Italy, Spain, Denmark and the UK

Literature on sex occupational segregation has typically focused on the micro and macro determinants of it, on mobility patterns over the life course, on implications of segregation and mobility for gender inequalities. Rarely the link between sex-type occupations and women’s risk of labour market interruptions over family formation has been explored. In this piece of work we shall analyse whether women who are working in the female-dominated, male-dominated or integrated occupations have more or less chances to remain attached to the labour market, controlling for qualifications, class, sector and contract positions. By drawing from ECHP, and comparing Italy, Spain, Denmark and the UK, we shall in particular see whether such connection varies across countries with different institutional and cultural configurations.We find that, ceteris paribus, only in the UK the sex-composition of an occupation matters: women in female occupations are more likely to move to inactivity than women in mixed or male occupations. In the other countries considered the main cleavages lie elsewhere. In Italy what matters most is the sector of employment (public vs. private). In Spain the sector is relevant too, but also social class and the type of contract held (permanent vs. temporary). In Denmark women’s transitions to inactivity are largely independent of human capital and job characteristics.

Unstable equilibrium: young adult women in family and career formation in Southern Europe

The paper examines the relationship between family formation (i.e., living with a partner and having children) and women’s occupational career in southern Europe (i.e., Greece, Italy, Portugal and Spain). The relationship is explored by analysing the impact that different family structures and male [nvolvement in caring activities have on women’s early occupational trajectories (i.e., remaining in the same occupational status, experiencing downward or upward mobility, or withdrawing from paid work). This research shows that male involvement in caring activities does not really push women ahead in their career, but the absolute lack of male support seems to negatively affect women’s permanence in paid work. These results apply to all southern European countries except Portugal, where the absolute absence of the partners’ support in caring activities does not seem to alter women’s determination to remain in paid work. The methodology applied consists of the estimation of multinomial logit regression models and the analysis is based on eight waves (1994-2001) of the European Community Household Panel (ECHP).

The Effect of occupational sex-composition on earnings: job-specialisation, sex-role attitudes and the division of domestic-labour in Spain

Important theoretical controversies remain unresolved in the literatire on occupational sex-segregation and the gender wage-gap. A useful way of summarising these controversies is viewing them as a debate between - cultural -socialisation. The paper discusses these theories in detail and carries out a preliminary test of the relative explanatory performance of some of their most consequential predictions. This is done by drawing on the Spanish sample of the second wave of the European Social Survey, ESS. The empirical analysis of ESS data illustrates the notable analytical pay-offs that can stem from using rich individual-level indicators, but also exemplifies the statistical llimitations generated by small sample size and high rates of non-response. Empirical results should, therefore, be taken as preliminary. They seem to suggest that the effect of occupational sex-segregation on wages could be explicable by workers' sex-role attitutes, their relative input in domestic production and the job-specific human capital requirements of their jobs. Of these three factors, job-specialisation seeems clearly the most important one.

The Role of social institutions in inter-generational mobility

In this study we examine the role of institutions in shaping inter-generational mobility behavior. Research has traditionally emphasized the role of educational systems but cummulative evidence suggests that variations in their design offer only a very limited explanation for observed mobility differences. We examine the impact of welfare states and, in particular, how early childhood and family policies may influence the impact of economic and cultural characteristics of origin families on child outcomes.

Upgrading or polarization? occupational change in Britain, Germany, Spain and Switzerland, 1990-2008

This paper analyzes the pattern of occupational change in four Western European countries over the last two decades: what kind of jobs have been expanding -- high-paid jobs, low-paid jobs or both? By addressing this issue, we also examine what theoretical account is consistent with the observed pattern of change: skill-biased technical change, skill supply evolution or wage-setting institutions? Our empirical findings show a picture of massive occupational upgrading that closely matches educational expansion. In all four countries, by far the strongest employment growth occurred at the top of the occupational hierarchy, among managers and professionals. Yet in parallel, in Britain and Switzerland, as well as in Germany and Spain after 1996 and 2002 respectively, relative employment declined more strongly in the middling occupations (among clerks and production workers) than at the bottom (among interpersonal service workers). This slightly polarized pattern of occupational upgrading is consistent with the "routinization" hypothesis that technology is a better substitute for average-paid jobs in production and the office that for low-paid jobs in interpersonal services. However, we find large cross-country differences in the employment evolution at the bottom of the occupational hierarchy, among low-paid services workers: sizeable growth in Britain and Spain, but stagnation in Germany and Switzerland. This results points towards the possibility that wage-setting institutions filter the pattern of occupational change.

Occupational sex-composition and earnings : individual and social effects

This paper investigates the micro and macro-level factors affecting the empirical association between occupational sex-composition and individual earnings. This is done in two analytical steps using data from the second round of the European Social Survey. In a first step, country-fixed-effects regressions are used to test the extent to which job-specialization, gender attitudes and the relative supply of domestic work can account for the impact of occupational sex-composition on earnings. In accordance with previous research, it is found that all these micro-level variables have a significant effect on the analyzed association, yet only job-specialization can explain it away by itself. In a second analytical step, macro-level interactions are tested under the hypothesis that defamilialization policies reduce the pay-offs of sphere specialization by sex, generating incentives for all types of women to invest in the labor market. Empirical results suggest that gender attitudes and the relative supply of housework are much more loosely associated to earning in social-democratic and former communist societies than in conservative or liberal regimes. This finding is interpreted as consistent with the defamilialization hypothesis.

Asymmetries in the opportunity structure. Intergenerational mobility trends in Europe

It remains unclear whether social mobility is increasing in the advancednations. The answer may depend on mobility patterns within very recentbirth cohorts. We use the inter-generational module in the 2005 EUSILCwhich allows us to include more recent cohorts. Comparingacross two Nordic and three Continental European countries, weestimate inter-generational mobility trends for sons both indirectly, viasocial origin effects on educational attainment, and directly in terms ofadult income attainment. In line with other studies we find substantiallymore mobility in Scandinavia, but also that traditionally less mobilesocieties, like Spain, are moving towards greater equality. We focusparticularly on non-linear relations. Most interestingly, we revealevident asymmetries in the process of equalizing life chances, inDenmark. The disadvantages associated with low social class originshave largely disappeared, but the advantages related to privilegedorigins persist.

Intergenerational mobility and the informative content of surnames

We propose an alternative method for measuring intergenerational mobility. Measurements obtained fromtraditional methods (based on panel data) are scarce, difficult to compare across countries and almost impossible to get across time. In particular, this means that we do not know how intergenerational mobility is correlated with growth, income or the degree of inequality.Our proposal is to measure the informative content of surnames in one census. The more information thesurname has on the income of an individual, the more important is her background in determining her outcomes; and thus, the less mobility there is.The reason is that surnames provide information about family relationships because the distribution ofsurnames is necessarily very skewed. A large percentage of the population is bound to have a very unfrequent surname. For them the partition generated by surnames is very informative on family linkages.First, we develop a model whose endogenous variable is the joint distribution of surnames and income.There, we explore the relationship between mobility and the informative content of surnames. We allow for assortative mating to be a determinant of both.Second, we use our methodology to show that in large Spanish region the informative content of surnamesis large and consistent with the model. We also show that it has increased over time, indicating a substantial drop in the degree of mobility. Finally, using the peculiarities of the Spanish surname convention we show that the degree of assortative mating has also increased over time, in such a manner that might explain the decrease in mobility observed.Our method allows us to provide measures of mobility comparable across time. It should also allow us tostudy other issues related to inheritance.

Foreign direct investments and spillovers through workers' mobility

We analyze a model where a multinational firm can use its superiortechnology in a foreign subsidiary only after appropriate trainingof local managers. Technological spillovers from foreign directinvestment arise when such managers are later hired by a localfirm. Benefits for the host economy may also take the form of therent that trained managers receive by the foreign affiliate toprevent them from moving to local competitors. We study conditionsunder which technological spillovers occur. We also show that undercertain circumstances the multinational firm might find it optimalto resort to export instead of foreign direct investment, to avoiddissipation of its intangible assets.

A positive theory of geographic mobility and social insurance

This paper presents a tractable dynamic general equilibrium model thatcan explain cross-country empirical regularities in geographical mobility,unemployment and labor market institutions. Rational agents vote overunemployment insurance (UI), taking the dynamic distortionary effects ofinsurance on the performance of the labor market into consideration.Agents with higher cost of moving, i.e., more attached to their currentlocation, prefer more generous UI. The key assumption is that an agent'sattachment to a location increases the longer she has resided there. UIreduces the incentive for labor mobility and increases, therefore, thefraction of attached agents and the political support for UI. The mainresult is that this self-reinforcing mechanism can give rise to multiplesteady-states-one 'European' steady-state featuring high unemployment,low geographical mobility and high unemployment insurance, and one'American' steady-state featuring low unemployment, high mobility andlow unemployment insurance.