Report No. 3: Assessment of Possible Migration Pressure and its Labour Market Impact Following EU Enlargement to Central and Eastern Europe

Study for the Department for Education and Employment of the United Kingdom, Bonn 1999 (117 pages).

On the recombination in high-order harmonic generation in molecules

We show that the dependence of high-order harmonic generation (HHG) on the molecular orientation can be understood within a theoretical treatment that does not involve the strong field of the laser. The results for H_2 show excellent agreement with time-dependent strong field calculations for model molecules, and this motivates a prediction for the orientation dependence of HHG from the N_2 3s_g valence orbital. For both molecules, we find that the polarization of recombination photons is influenced by the molecular orientation. The variations are particularly pronounced for the N_2 valence orbital, which can be explained by the presence of atomic p-orbitals.Comment: 6 pages 7 figure

Conversion efficiency and luminosity for gamma-proton colliders based on the LHC-CLIC or LHC-ILC QCD Explorer scheme

Gamma-proton collisions allow unprecedented investigations of the low x and high $Q^{2}$ regions in quantum chromodynamics. In this paper, we investigate the luminosity for "ILC"$\times$LHC ($\sqrt{s_{ep}}=1.3$ TeV) and "CLIC"$\times$LHC ($\sqrt{s_{ep}}=1.45$ TeV) based $\gamma p$ colliders. Also we determine the laser properties required for high conversion efficiency.Comment: 16, 6 figure

Occupational Mobility of Ethnic Migrants

This paper studies occupational mobility of ethnic German migrants who have entered Germany since 1984. The empirical analysis suggests significant differences in the probability of downward occupational mobility by gender, immigration status, and schooling levels. In general, migrants with higher skill levels face sharper deteriorations in their relative labor market position at the time of immigration, but are also able to reach their original occupational status much faster than low-skilled immigrants

Immigration Policy in Integrated National Economies

Migration is an unavoidable aspect of globalization. While full flexibility is politically unfeasible, the paper argues for regulated openness. Migration in the age of globalization should be judged according to the labor market needs of the receiving countries. This would also serve best the demands of political leaders that seek reelection. Voters are happier with migrants if they are largely selected according to their value to the economy. In the current situation in developed countries it is best to select skilled migrants, and those who can produce non-tradable services. The need to import skilled labor might be limited by virtual migration through the Internet

Overtime Work and Overtime Compensation in Germany

Sharing the available stock of work more fairly is a popular concern in the public policy debate. One policy proposal is to reduce overtime work in order to allow the employment of more people. This paper suggests that such a concept faces major problems. Using Germany as a case study, it is shown that the group of workers with the highest risks of becoming unemployed, namely the unskilled, also exhibit low levels of overtime work. Those who work overtime, namely the skilled, face excess demand on the labour market. Since skilled and unskilled workers are largely complements in production, a general reduction in overtime will lead to less production and hence also to a decline in the level of unskilled employment. The paper provides empirical support for this line of argument. It is also shown that paid overtime work has lost relative importance over time

Beam-beam studies for the High-Energy LHC

LHC upgrades are being considered both towards higher luminosity (HL-LHC) and towards higher energy (HE-LHC). In this paper we report initial studies of the beam-beam effects in the HE-LHC [1]. The HE-LHC aims at beam energies of 16.5 TeV, where the transverse emittance decreases due to synchrotron radiation with a 2-hour damping time. As a result of this emittance, shrinkage the beam-beam parameter increases with time, during a physics store. The beam-beam limit in the HE-LHC is explored using computer simulations.Comment: 6 pages, contribution to the EuCARD-AccNet-EuroLumi Workshop: The High-Energy Large Hadron Collider, Malta, 14 -- 16 Oct 201

Überstundenarbeit und Überstundenkompensation in Deutschland

Im Rahmen der Diskussion zur Lösung des deutschen Beschäftigungsproblems wird als potentieller Lösungsweg die Umverteilung des bestehenden Bestandes an Arbeit gefordert. Erst kürzlich wurde wieder die Verringerung von Überstunden durch die Bundesanstalt für Arbeit und im Rahmen der Gespräche zum „Bündnis für Arbeit" thematisiert. Kann eine derartige Politik zu einer signifikanten Verringerung der Arbeitslosigkeit führen? Oder gibt es auch Mechanismen, die das Gegenteil befürchten lassen? --

Provenance for SPARQL queries

Determining trust of data available in the Semantic Web is fundamental for applications and users, in particular for linked open data obtained from SPARQL endpoints. There exist several proposals in the literature to annotate SPARQL query results with values from abstract models, adapting the seminal works on provenance for annotated relational databases. We provide an approach capable of providing provenance information for a large and significant fragment of SPARQL 1.1, including for the first time the major non-monotonic constructs under multiset semantics. The approach is based on the translation of SPARQL into relational queries over annotated relations with values of the most general m-semiring, and in this way also refuting a claim in the literature that the OPTIONAL construct of SPARQL cannot be captured appropriately with the known abstract models.Comment: 22 pages, extended version of the ISWC 2012 paper including proof