Intergenerational mobility of socio-economic status in comparative perspective

This paper reviews three strands of literature on socio-economic intergenerational mobility. The first is a mostly recent and rapidly growing economics literature that measures mobility in labour earnings and income. This approach is compared with two classical sociological approaches that measure the mobility in class and status. The United States seems to rank quite high in terms of class and status mobility, but low in terms of earnings and income mobility. This seemingly contradictory result can be accounted for by lower earnings mobility within occupations in the United States.

The opportunistic replacement and inspection problem for components with a stochastic life time

The problem of finding efficient maintenance and inspection schemes in the case of components with a stochastic life time is studied and a mixed integer programming solution is proposed. The problem is compared with the two simpler problems of which the studied problem is a generalisation: The opportunistic replacement problem, assuming components with a deterministic life time and The opportunistic replacement problem for components with a stochastic life time, for maintenance schemes without inspections

Nature and Nurture in the Intergenerational Transmission of Socioeconomic Status: Evidence from Swedish Children and Their Biological and Rearing Parents

This study uses an extraordinary Swedish data set to explore the sources of the intergenerational transmission of socioeconomic status. Merging data from administrative sources and censuses, we investigate the association between sons' and daughters' socioeconomic outcomes and those of their biological and rearing parents. Our analysis focuses on children raised in six different family circumstances: raised by both biological parents, raised by the biological mother without a stepfather, raised by the biological mother with a stepfather, raised by the biological father without a stepmother, raised by the biological father with a stepmother, and raised by two adoptive parents. Relative to the existing literature, the most remarkable feature of our data set is that it contains information on the biological parents even when they are not the rearing parents. We specify a simple additive model of pre-birth (including genetic) and post-birth influences and examine the model's ability to provide a unified account of the intergenerational associations in all six family types. Our results suggest substantial roles for both pre-birth and post-birth factors.

Interaction induced edge channel equilibration

The electronic distribution functions of two Coulomb coupled chiral edge states forming a quasi-1D system with broken translation invariance are found using the equation of motion approach. We find that relaxation and thereby energy exchange between the two edge states is determined by the shot noise of the edge states generated at a quantum point contact (QPC). In close vicinity to the QPC, we derive analytic expressions for the distribution functions. We further give an iterative procedure with which we can compute numerically the distribution functions arbitrarily far away from the QPC. Our results are compared with recent experiments of Le Sueur et al..Comment: 10 pages, 7 figures, includes 5 pages of supplementary informatio

Forming chondrules in impact splashes. I. Radiative cooling model

The formation of chondrules is one of the oldest unsolved mysteries in meteoritics and planet formation. Recently an old idea has been revived: the idea that chondrules form as a result of collisions between planetesimals in which the ejected molten material forms small droplets which solidify to become chondrules. Pre-melting of the planetesimals by radioactive decay of 26Al would help producing sprays of melt even at relatively low impact velocity. In this paper we study the radiative cooling of a ballistically expanding spherical cloud of chondrule droplets ejected from the impact site. We present results from a numerical radiative transfer models as well as analytic approximate solutions. We find that the temperature after the start of the expansion of the cloud remains constant for a time t_cool and then drops with time t approximately as T ~ T_0[(3/5)t/t_cool+ 2/5]^(-5/3) for t>t_cool. The time at which this temperature drop starts t_cool depends via an analytical formula on the mass of the cloud, the expansion velocity and the size of the chondrule. During the early isothermal expansion phase the density is still so high that we expect the vapor of volatile elements to saturate so that no large volatile losses are expected

Equality of Opportunity and the Distribution of Long-Run Income in Sweden

Equality of opportunity is an ethical goal with almost universal appeal. The interpretation taken here is that a society has achieved equality of opportunity if it is the case that what individuals accomplish, with respect to some desirable objective, is determined wholly by their choices and personal effort, rather than by circumstances beyond their control. We use data for Swedish men born between 1955 and 1967 for whom we measure the distribution of long-run income, as well as several important background circumstances, such as parental education and income, family structure and own IQ before adulthood. We address the question: in Sweden, given its present constellation of social policies and institutions, to what extent is existing income inequality due to circumstances, as opposed to 'effort'? Our results suggest that several circumstances, importantly both parental income and own IQ, are important for long-run income inequality, but that variations in individual effort account for the most part of that inequality.equality of opportunity, family background, inequality, long-run income

IQ and Family Background: Are Associations Strong or Weak?

For the purpose of understanding the underlying mechanisms behind intergenerational associations in income and education, recent studies have explored the intergenerational transmission of abilities. We use a large representative sample of Swedish men to examine both intergenerational and sibling correlations in IQ. Since siblings share both parental factors and neighbourhood influences, the sibling correlation is a broader measure of the importance of family background than the intergenerational correlation. We use IQ data from the Swedish military enlistment tests. The correlation in IQ between fathers (born 1951-1956) and sons (born 1966-1980) is estimated to 0.347. The corresponding estimate for brothers (born 1951-1968) is 0.473, suggesting that family background explains approximately 50% of a person's IQ. Estimating sibling correlations in IQ we thus find that family background has a substantially larger impact on IQ than has been indicated by previous studies examining only intergenerational correlations in IQ.ability, intergenerational mobility, family background

Search Problems in Trees with Symmetries: Near Optimal Traversal Strategies for Individualization-Refinement Algorithms

We define a search problem on trees that closely captures the backtracking behavior of all current practical graph isomorphism algorithms. Given two trees with colored leaves, the goal is to find two leaves of matching color, one in each of the trees. The trees are subject to an invariance property which promises that for every pair of leaves of equal color there must be a symmetry (or an isomorphism) that maps one leaf to the other. We describe a randomized algorithm with errors for which the number of visited nodes is quasilinear in the square root of the size of the smaller of the two trees. For inputs of bounded degree, we develop a Las Vegas algorithm with a similar running time. We prove that these results are optimal up to logarithmic factors. For this, we show a lower bound for randomized algorithms on inputs of bounded degree that is the square root of the tree sizes. For inputs of unbounded degree, we show a linear lower bound for Las Vegas algorithms. For deterministic algorithms we can prove a linear bound even for inputs of bounded degree. This shows why randomized algorithms outperform deterministic ones. Our results explain why the randomized "breadth-first with intermixed experimental path" search strategy of the isomorphism tool Traces (Piperno 2008) is often superior to the depth-first search strategy of other tools such as nauty (McKay 1977) or bliss (Junttila, Kaski 2007). However, our algorithm also provides a new traversal strategy, which is theoretically near optimal and which has better worst case behavior than traversal strategies that have previously been used

Parallel Computation of Combinatorial Symmetries

In practice symmetries of combinatorial structures are computed by transforming the structure into an annotated graph whose automorphisms correspond exactly to the desired symmetries. An automorphism solver is then employed to compute the automorphism group of the constructed graph. Such solvers have been developed for over 50 years, and highly efficient sequential, single core tools are available. However no competitive parallel tools are available for the task. We introduce a new parallel randomized algorithm that is based on a modification of the individualization-refinement paradigm used by sequential solvers. The use of randomization crucially enables parallelization. We report extensive benchmark results that show that our solver is competitive to state-of-the-art solvers on a single thread, while scaling remarkably well with the use of more threads. This results in order-of-magnitude improvements on many graph classes over state-of-the-art solvers. In fact, our tool is the first parallel graph automorphism tool that outperforms current sequential tools