Quantum state sensitivity to initial conditions

The different time-dependent distances of two arbitrarily close quantum or classical-statistical states to a third fixed state are shown to imply an experimentally relevant notion of state sensitivity to initial conditions. A quantitative classification scheme of quantum states by their sensitivity and instability in state space is given that reduces to the one performed by classical-mechanical Lyapunov exponents in the classical limitComment: 1 .tex file and 2 .ps figures. Physical Review A (to appear 1 May

Girls like pink: Explaining sex-typed occupational aspirations amongst young children

There is a high degree of sex-typing in young children's occupational aspirations and this has consequences for subsequent occupational segregation. Sociologists typically attribute early sex-differences in occupational preferences to gender socialization. Yet we still know surprisingly little about the mechanisms involved in the intergenerational transmission of sex-typical preferences and there is considerable theoretical controversy regarding the role of individual agency in the process of preference formation. This study analyzes the determinants of sex-typed occupational aspirations amongst British children aged between 11 and 15. We specify different mechanisms involved in the transmission of sex-typical preferences and propose an innovative definition of individual agency that is anchored in observable psychological traits linked to self-direction. This allows us to perform a simultaneous test of socialization and agency predictors of occupational sex-typing. We find that parental influences on occupational preferences operate mainly through three distinctive channels: 1) the effect that parental socio-economic resources have on the scope of children‘s occupational aspirations, 2) children's direct imitation of parental occupations, and 3) children's learning of sex-typed roles via the observation of parental behavior. We also find a strong net effect of children's own psychological predispositions —self-esteem in particular— on the incidence of sex-typical occupational preferences. Yet large differences in the occupational aspirations of girls and boys remain unexplained.Gender segregation; occupational aspirations; children; socialization; agency; personality traits; mechanisms; british household panel survey

Socially-embedded investments: Explaining gender differences in job-specific skills

Gender-differences in post-schooling skill investments play a central role in stratification processes. Yet little research has been devoted to explaining how these differences come about. This paperhelps to fill this gap by proposing and testing a job-investment model with social-interaction effects that melds substantive ideas of sociology and economics. Firms use strategic compensation profiles in order to protect their job-specific skill investments and this shifts the weight of the investment decision to the supply side. Employees consider the tenure-reward profiles of different job-specific investment options and chose rationally on the basis of their expected survival probabilities in each of them. Given uncertainty, actors are likely to inform their job-survival expectations by observing their social context. Three different forms of social influence are distinguished: social-learning,social norms and role identification. It is further argued that social influences on job-survival expectations can be identified empirically by blocking individuals\' work and family preferences. Several hypotheses are derived and tested to a subsample of approximately 2,700 young single wage-earners nested in 261 different European regions and 24 different European countries. Results show that young women\'s job-investment decisions are significantly correlated with 1) the social visibility of women in highly specialized jobs in the preceding generation; 2) the proportion of men who do housework in their potential marriage markets, and 3) the existing fertility norms.gender; job-specific investments; social interactions; strategic compensation; social learning; social norms; role identification; prefrences; european social survey

Entropy involved in fidelity of DNA replication

Information has an entropic character which can be analyzed within the Statistical Theory in molecular systems. R. Landauer and C.H. Bennett showed that a logical copy can be carried out in the limit of no dissipation if the computation is performed sufficiently slowly. Structural and recent single-molecule assays have provided dynamic details of polymerase machinery with insight into information processing. We introduce a rigorous characterization of Shannon Information in biomolecular systems and apply it to DNA replication in the limit of no dissipation. Specifically, we devise an equilibrium pathway in DNA replication to determine the entropy generated in copying the information from a DNA template in the absence of friction. Both the initial state, the free nucleotides randomly distributed in certain concentrations, and the final state, a polymerized strand, are mesoscopic equilibrium states for the nucleotide distribution. We use empirical stacking free energies to calculate the probabilities of incorporation of the nucleotides. The copied strand is, to first order of approximation, a state of independent and non-indentically distributed random variables for which the nucleotide that is incorporated by the polymerase at each step is dictated by the template strand, and to second order of approximation, a state of non-uniformly distributed random variables with nearest-neighbor interactions for which the recognition of secondary structure by the polymerase in the resultant double-stranded polymer determines the entropy of the replicated strand. Two incorporation mechanisms arise naturally and their biological meanings are explained. It is known that replication occurs far from equilibrium and therefore the Shannon entropy here derived represents an upper bound for replication to take place. Likewise, this entropy sets a universal lower bound for the copying fidelity in replication.Comment: 25 pages, 5 figure

Socially embedded investments: explaining gender differences in job-specific skills

This article offers an innovative explanation for gender differences in job specialization that connects individual choices to the social structure. Decisions about jobs are modeled as a choice over different tenure-reward slopes, which are steeper for more specialized skills. The choice of job depends on expected duration. Individuals have imperfect information about their probability of success in different jobs and form expectations partly by observing the social context. Because women face greater constraints and uncertainties than men, their choices depend more on this context. Contextual influences on job specialization are tested for European respondents nested in 234 different regions. Consonant with the theory's predictions, women are found to have more specialized jobs in regions where (1) the preceding generation's job specialization diverged less by gender, (2) peers arrange a more equal division of housework, and (3) peers have fewer children.Pubblicad

Domestic supply, job-specialisation and sex-differences in pay

This paper proposes an explanation of sex-differences in job-allocation and pay. Job allocation calculations are considered to be related to 1) the distribution of housework and 2) the skill-specialization requirements of jobs. Both elements combined generate a particular incentive structure for each sex. Welfare policies and services can, however, lower the risks of skill-depreciation for women as well as increase their intra-household bargaining power, hence reducing the economic pay-offs of traditional spherespecialization by sex. The implications of this model for earnings are tested using data from the second round of the European Social Survey. Results seem consistent with the model predictions