Sorting and the Output Loss due to Search Frictions

We analyze a general search model with on-the-job search and sorting of heterogeneous workers into heterogeneous jobs. This model yields a simple relationship between (i) the unemployment rate, (ii) the value of non-market time, and (iii) the max-mean wage differential. The latter measure of wage dispersion is more robust than measures based on the reservation wage, due to the long left tail of the wage distribution. We estimate this wage differential using data on match quality and allow for measurement error. The estimated wage dispersion and mismatch for the US is consistent with an unemployment rate of 4-6%. We find that without search frictions, output would be between 7.5% and 18.5% higher, depending on whether or not firms can ex ante commit to wage payments.on-the-job search, wage dispersion, mismatch, output loss due to frictions

The Right Man for the Job: Increasing Returns in Search?

This paper describes a search model with a continuum of worker and job types, transferable utility and an IRS contact technology. We apply a second order Taylor expansion to derive an analytical solution of the equilibrium. We find that one third of the increasing returns in contacts are absorbed by firms and workers being more choosy. Hence, strongly increasing returns in contact rates are consistent with weakly increasing returns in matching. In addition, we derive and decompose the efficiency loss due to inadequate incentives and show how unemployment benefits can reduce the loss. Finally, we derive a relation between the size of the surplus due to search frictions and the degree of substitutability of worker types at given job complexity levels. Numerical simulations of the model show that our approximations are quite accurate.

Sin City?

Is moving to the countryside a credible commitment device for couples? We investigate whether lowering the arrival rate of potential alternative partners by moving to a less populated area lowers the dissolution risk for a sample of Danish couples. We find that of the couples who married in the city, the ones who stay in the city have significant higher divorce rates. Similarly, for the couples who married outside the city, the ones who move to the city are more likely to divorce. This correlation can be explained by both a causal and a sorting effect. We disentangle them by using the timing-of-events approach. In addition we use information on father’s location as an instrument. We find that the sorting effect dominates. Moving to the countryside is therefore not a cheap way to prolong relationships.dissolution; search; mobility; city

Ideology and culture

This chapter evaluates the role of culture and ideology in relation to journalism. Journalists cannot ignore that they are not operating in a vacuum, immune to environmental influences. A “western” (or any ideological) approach to journalism is not a neutral norm to which others need to adhere. Journalists can keep themselves and each other in check by questioning the approach taken to a story and identifying the lens they employ. Secondly, diverse recruitment within media organisations is key, not just in terms of ethnic, gender or national backgrounds but also in terms of value profiles. There is no one Nation which holds the gold standard for journalism and can be used as a reference point for all others. In other words, there is no such thing as Greenwich Mean Time journalism

A Bi-Directional Refinement Algorithm for the Calculus of (Co)Inductive Constructions

The paper describes the refinement algorithm for the Calculus of (Co)Inductive Constructions (CIC) implemented in the interactive theorem prover Matita. The refinement algorithm is in charge of giving a meaning to the terms, types and proof terms directly written by the user or generated by using tactics, decision procedures or general automation. The terms are written in an "external syntax" meant to be user friendly that allows omission of information, untyped binders and a certain liberal use of user defined sub-typing. The refiner modifies the terms to obtain related well typed terms in the internal syntax understood by the kernel of the ITP. In particular, it acts as a type inference algorithm when all the binders are untyped. The proposed algorithm is bi-directional: given a term in external syntax and a type expected for the term, it propagates as much typing information as possible towards the leaves of the term. Traditional mono-directional algorithms, instead, proceed in a bottom-up way by inferring the type of a sub-term and comparing (unifying) it with the type expected by its context only at the end. We propose some novel bi-directional rules for CIC that are particularly effective. Among the benefits of bi-directionality we have better error message reporting and better inference of dependent types. Moreover, thanks to bi-directionality, the coercion system for sub-typing is more effective and type inference generates simpler unification problems that are more likely to be solved by the inherently incomplete higher order unification algorithms implemented. Finally we introduce in the external syntax the notion of vector of placeholders that enables to omit at once an arbitrary number of arguments. Vectors of placeholders allow a trivial implementation of implicit arguments and greatly simplify the implementation of primitive and simple tactics

Marriage and the City

Do people move to cities because of marriage market considerations? In cities singles can meet more potential partners than in rural areas. Singles are therefore prepared to pay a premium in terms of higher housing prices. Once married, the marriage market benefits disappear while the housing premium remains. We extend the model of Burdett and Coles (1997) with a distinction between efficient (cities) and less efficient (non-cities) search markets. One implication of the model is that singles are more likely to move from rural areas to cities while married couples are more likely to make the reverse movement. A second prediction of the model is that attractive singles benefit most from a dense market (i.e. from being choosy). Those predictions are tested with a unique Danish dataset

Sin City?

Is moving to the countryside a credible commitment device for couples? We investigate whether lowering the arrival rate of potential alternative partners by moving to a less populated area lowers the dissolution risk for a sample of Danish couples. We find that of the couples who married in the city, the ones who stay in the city have significant higher divorce rates. Similarly, for the couples who married outside the city, the ones who move to the city are more likely to divorce. This correlation can be explained by both a causal and a sorting effect. We disentangle them by using the timing-of-events approach. In addition we use information on father's location as an instrument. We find that the sorting effect dominates. Moving to the countryside is therefore not a cheap way to prolong relationships

Fundamental noise limitations to supercontinuum generation in microstructure fiber

Broadband noise on supercontinuum spectra generated in microstructure fiber is shown to lead to amplitude fluctuations as large as 50 % for certain input laser pulse parameters. We study this noise using both experimental measurements and numerical simulations with a generalized stochastic nonlinear Schroedinger equation, finding good quantitative agreement over a range of input pulse energies and chirp values. This noise is shown to arise from nonlinear amplification of two quantum noise inputs: the input pulse shot noise and the spontaneous Raman scattering down the fiber.Comment: 16 pages with 6 figure

Risk and protective factors for meningococcal disease in adolescents: matched cohort study

Objective: To examine biological and social risk factors for meningococcal disease in adolescents. Design: Prospective, population based, matched cohort study with controls matched for age and sex in 1:1 matching. Controls were sought from the general practitioner. Setting: Six contiguous regions of England, which represent some 65% of the country’s population. Participants: 15-19 year olds with meningococcal disease recruited at hospital admission in six regions (representing 65% of the population of England) from January 1999 to June 2000, and their matched controls. Methods: Blood samples and pernasal and throat swabs were taken from case patients at admission to hospital and from cases and matched controls at interview. Data on potential risk factors were gathered by confidential interview. Data were analysed by using univariate and multivariate conditional logistic regression. Results: 144 case control pairs were recruited (74 male (51%); median age 17.6). 114 cases (79%) were confirmed microbiologically. Significant independent risk factors for meningococcal disease were history of preceding illness (matched odds ratio 2.9, 95% confidence interval 1.4 to 5.9), intimate kissing with multiple partners (3.7, 1.7 to 8.1), being a university student (3.4, 1.2 to 10) and preterm birth (3.7, 1.0 to 13.5). Religious observance (0.09, 0.02 to 0.6) and meningococcal vaccination (0.12, 0.04 to 0.4) were associated with protection. Conclusions: Activities and events increasing risk for meningococcal disease in adolescence are different from in childhood. Students are at higher risk. Altering personal behaviours could moderate the risk. However, the development of further effective meningococcal vaccines remains a key public health priority