The transfer matrix in four-dimensional Causal Dynamical Triangulations

Causal Dynamical Triangulations is a background independent approach to quantum gravity. In this paper we introduce a phenomenological transfer matrix model, where at each time step a reduced set of quantum states is used. The states are solely characterized by the discretized spatial volume. Using Monte Carlo simulations we determine the effective transfer matrix elements and extract the effective action for the scale factor. In this framework no degrees of freedom are frozen, however, the obtained action agrees with the minisuperspace model.Comment: 8 pages, 3 figures, contribution to the proceedings of "Relativity and Gravitation - 100 years after Einstein in Prague" (Prague, June 2012

Seasonal migration and networks : evidence on Moldova's labour exodus.

Seasonal migration is an ever more important phenomenon worldwide, but has received little attention in empirical research. This paper investigates the choice of seasonal versus longer-term migration on a household level. We use data from Moldova, a country that is witnessing a massive emigration shock. Surprisingly, neither children nor marital status appear to influence the decision to leave seasonally or for longer periods. This suggests high social and emotional costs of emigration. We also find that existing local networks of seasonal migrants are unrelated to permanent migration choice. Generally, networks appear to have a stronger influence on migration probabilities in urban settings.Saisonarbeitskräfte; Auswanderung; Armut; Soziales Netzwerk; Soziale Lage; Motivation; Migranten; Schätzung; Moldawien;Migration; Seasonal Migration; Migration Network; Poverty; Moldova;

Wage Inequality and the Changing Organization of Work.

This paper sheds light on how changes in the organization of work lead to wage inequality. We present a theoretical model in which workers with a wider span of competence (higher level of multitasking) earn a wage premium. Since abilities and opportunities to expand the span of competence are distributed unequally among workers across and within education groups, our theory explains (1) rising wage inequality between groups, (2) rising wage inequality within groups, and (3) the polarization of work and the decoupling of the income distribution. Using a rich German data set covering a 20-year period from 1986 to 2006, we provide empirical support for our model.

Human Capital Depreciation during Family-related Career Interruptions in Male and Female Occupations

Human Capital Depreciation during Family-related Career Inter¬ruptions in Male and Female Occupations This study investigates the relation between human capital depreciation during family-related career interruptions and occupational choice of women in the (West) German labour market. In contrast to other studies that do not explicitly focus on family-related career interruptions, we find that short-term human capital depreciation during these career interruptions is significantly lower in female occupations than in male occupations. This holds for both high- and low-skilled occupations. Our findings support the self-selection hypothesis with respect to occupational sex segregation, i.e. women might deliberately choose female occupations because of lower short-term wage penalties for family-related career interruptions. Moreover, we find that particularly men employed in high-skilled male occupations face large short-run as well as long run wage penalties when they have a family related career break.education, training and the labour market;

A c=1 phase transition in two-dimensional CDT/Horava-Lifshitz gravity?

We study matter with central charge $c >1$ coupled to two-dimensional (2d) quantum gravity, here represented as causal dynamical triangulations (CDT). 2d CDT is known to provide a regularization of (Euclidean) 2d Ho\v{r}ava-Lifshitz quantum gravity. The matter fields are massive Gaussian fields, where the mass is used to monitor the central charge $c$. Decreasing the mass we observe a higher order phase transition between an effective $c=0$ theory and a theory where $c>1$. In this sense the situation is somewhat similar to that observed for "standard" dynamical triangulations (DT) which provide a regularization of 2d quantum Liouville gravity. However, the geometric phase observed for $c >1$ in CDT is very different from the corresponding phase observed for DT.Comment: 16 pages, 10 figure

Distribution of periodic trajectories of Anosov C-system

The hyperbolic Anosov C-systems have a countable set of everywhere dense periodic trajectories which have been recently used to generate pseudorandom numbers. The asymptotic distribution of periodic trajectories of C-systems with periods less than a given number is well known, but a deviation of this distribution from its asymptotic behaviour is less known. Using fast algorithms, we are studying the exact distribution of periodic trajectories and their deviation from asymptotic behaviour for hyperbolic C-systems which are defined on high dimensional tori and are used for Monte-Carlo simulations. A particular C-system which we consider in this article is the one which was implemented in the MIXMAX generator of pseudorandom numbers. The generator has the best combination of speed, reasonable size of the state, and availability for implementing the parallelization and is currently available generator in the ROOT and CLHEP software packages at CERN.Comment: 22 pages, 14 figure

Euclidean 4D quantum gravity with a non-trivial measure term

Dynamical Triangulations provide us with a lattice regularization of four-dimensional Euclidean quantum gravity within the realm of ordinary quantum field theory. We add a local measure term, which can also serve as a generalized higher curvature term, and explore an extended coupling constant space. We determine the phase diagram of this model using non-degenerated triangulations. A first order phase transition line is observed, but no second order transition point is located. In consequence we cannot attribute any continuum physics interpretation to the so-calledcrinkled phase of 4D dynamical triangulations

Back to normal? The future of global production networks.

It is neither likely nor desirable for central banks to exit from unconventional monetary policies in the near future. However, it is important that central banks develop an exit strategy, evaluate the merits of new and old monetary policy tools and communicate with the public so as to maintain financial stability, support economic growth and minimize future inflationary risks. Central bank communication policy will turn out to be crucial and more challenging than it was before the crisis.Wertschöpfung; Outsourcing; Business Network; Offshoring; Globalisierung; Wirtschaftskrise;