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

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

Numerical study of the photoelectron cloud in KEKB Low Energy Ring with a three-dimensional particle in cell method

A three-dimensional particle in cell simulation code has been developed to study the photoelectron cloud instabilities in KEKB LER. In this report, the program is described in detail. In particular, typical simulation results are presented for the photoelectron motion in various kinds of magnetic fields. The simulation shows that a solenoid is very effective in confining the photoelectrons to the vicinity of the vacuum chamber wall and in creating a region free of photoelectrons at the vacuum pipe center. The more uniform the solenoid field is, the more effectively does it suppress the electron-cloud buildup. Multipacting can occur both in a drift region and in a dipole magnet, and the heat load deposited on the chamber wall due to the lost electrons is important in these two cases. Electron trapping by the beam field as well as by various magnetic fields is an important phenomenon, especially inside quadrupole and sextupole magnets. Our numerical results qualitatively agree with the experimental studies

The FCC-ee Interaction Region Magnet Design

The design of the region close to the interaction point of the FCC-ee experiments is especially challenging. The beams collide at an angle (+-15 mrad) in the high-field region of the detector solenoid. Moreover, the very low vertical beta_y* of the machine necessitates that the final focusing quadrupoles have a distance from the IP (L*) of around 2 m and therefore are inside the main detector solenoid. The beams should be screened from the effect of the detector magnetic field, and the emittance blow-up due to vertical dispersion in the interaction region should be minimized, while leaving enough space for detector components. Crosstalk between the two final focus quadrupoles, only about 6 cm apart at the tip, should also be minimized.Comment: Poster presented at IPAC16, May 8-13, Busan, Kore

Catalytic hydrogenation of α,β-unsaturated carboxylic acid derivatives using copper(i)/N-heterocyclic carbene complexes

A simple and air-stable copper(I)/N-heterocyclic carbene complex enables the catalytic hydrogenation of enoates and enamides, hitherto unreactive substrates employing homogeneous copper catalysis and H2 as a terminal reducing agent. This atom economic transformation replaces commonly employed hydrosilanes and can also be carried out in an asymmetric fashion.TU Berlin, Open-Access-Mittel - 201