The Overlap Representation of Skewed Quark and Gluon Distributions

Within the framework of light-cone quantisation we derive the complete and exact overlap representation of skewed parton distributions for unpolarised and polarised quarks and gluons. Symmetry properties and phenomenological applications are discussed.Comment: LaTex, 36 pages. v2: incorrect paper attached originally. v3: erratum adde

Artificial intelligence as (meta-)art? Emergent technologies in the design process

Over the past decades, philosophy-of-science scholars have been questioning the epistemology of automated data analysis. Coming to the field of artif icial intelligence application in the design process, the debate has been less intense and articulate. The interest in developing a disciplinary discussion refers to the proactive quality of design, which aims at introducing artifacts into the physical world through the act of shaping, which includes a process of context interpretation. By acknowledging that the environment and its interpretation are inextricably bound to the design process, and by questioning the epistemology of automated analytics, we ask if artificial intelligence is not an aesthetic device producing outcomes that are a form of (meta-)art. Our hypothesis is that the models for automated data analysis do not satisfy the need for objectivity often expected through the application of parametric design because of their biases. However, as an aesthetic interpretation of a place, they inspire designers and stimulate their interpretation in the framework of the hermeneutic process of design, indicating an evolution toward a renewed “new-humanism,” a rediscovery of the creative agency of the designer in an un-hierarchical relationship with nature

Efficient qubit detection using alkali earth metal ions and a double STIRAP process

We present a scheme for robust and efficient projection measurement of a qubit consisting of the two magnetic sublevels in the electronic ground state of alkali earth metal ions. The scheme is based on two stimulated Raman adiabatic passages (STIRAP) involving four partially coherent laser fields. We show how the efficiency depends on experimentally relevant parameters: Rabi frequencies, pulse widths, laser linewidths, one- and two-photon detunings, residual laser power, laser polarization and ion motion.Comment: 14 pages, 15 figure

Thermal conductance of thin film YIG determined using Bayesian statistics

Thin film YIG (Y$_3$Fe$_5$O$_{12}$) is a prototypical material for experiments on thermally generated pure spin currents and the spin Seebeck effect. The 3-omega method is an established technique to measure the cross-plane thermal conductance of thin films, but can not be used in YIG/GGG (Ga$_3$Gd$_5$O$_{12}$) systems in its standard form. We use two-dimensional modeling of heat transport and introduce a technique based on Bayesian statistics to evaluate measurement data taken from the 3-omega method. Our analysis method allows us to study materials systems that have not been accessible with the conventionally used 3-omega analysis. Temperature dependent thermal conductance data of thin film YIG are of major importance for experiments in the field of spin-caloritronics. Here we show data between room temperature and 10 K for films covering a wide thickness range as well as the magnetic field effect on the thermal conductance between 10 K and 50 K

Offene Stabilisierung und Endoprothetik bei geriatrischen Patienten mit acetabulären Frakturen: Kombination minimal-invasiver Operationstechniken

Zusammenfassung: Acetabulumfrakturen des geriatrischen osteoporosekranken Patienten nach einem niederenergetischen Trauma gewinnen aufgrund demographischer Veränderungen zunehmend an Bedeutung. Die Ergebnisse der aktuellen therapeutischen Ansätze sind in dieser Patientenpopulation jedoch eher ungünstig, während Risiken und therapieinduzierte Morbidität sowohl der chirurgischen, als auch konservativen Therapieoptionen erheblich sind. Die Therapie geriatrischer Patienten ist nicht nur durch ihre häufig komplexe medizinische Vorgeschichte eine Herausforderung. Zusätzlich ist die schnelle funktionelle Rehabilitation und Rückkehr in ihre vorherige Lebenssituation essentiell, um einen körperlichen und geistigen Abbau zu verhindern. Hierin unterscheiden sie sich maßgeblich von jüngeren Patientenkollektiven, für die schlussendlich die langfristige Prognose entscheidend ist. Der vorliegende Artikel setzt sich kritisch mit der aktuellen Literatur auseinander und berichtet über erste Ergebnisse eines neuen chirurgischen Konzepts bei 6 geriatrischen Patienten im Alter zwischen 82 und 91Jahren. Aufgezeigt wird die Kombination eines minimal-invasiven vorderen Zugangs zur offenen Reposition und Stabilisation des Acetabulums, sowie eines minimal-invasiven vorderen Zugangs (AMIS®) für einen primären prothetischen Gelenkersat

Charge carrier density collapse in La_0.67Ca_0.33MnO_3 and La_0.67Sr_0.33MnO_3 epitaxial thin films

We measured the temperature dependence of the linear high field Hall resistivity of La_0.67Ca_0.33MnO_3 (T_C=232K) and La_0.67Sr_0.33MnO_3 (T_C=345K) thin films in the temperature range from 4K up to 360K in magnetic fields up to 20T. At low temperatures we find a charge carrier density of 1.3 and 1.4 holes per unit cell for the Ca- and Sr-doped compound, respectively. In this temperature range electron-magnon scattering contributes to the longitudinal resistivity. At the ferromagnetic transition temperature T_C a dramatic drop in the number of current carriers $n$ down to 0.6 holes per unit cell, accompanied by an increase in unit cell volume, is observed. Corrections of the Hall data due to a non saturated magnetic state will lead a more pronounced charge carrier density collapse.Comment: 5 pages, 5 EPS figures, submitted to Eur. Phys. J.

MaGICC-WDM: the effects of warm dark matter in hydrodynamical simulations of disc galaxy formation

We study the effect of warm dark matter (WDM) on hydrodynamic simulations of galaxy formation as part of the Making Galaxies in a Cosmological Context (MaGICC) project. We simulate three different galaxies using three WDM candidates of 1, 2 and 5 keV and compare results with pure cold dark matter simulations. WDM slightly reduces star formation and produces less centrally concentrated stellar profiles. These effects are most evident for the 1 keV candidate but almost disappear for $m_{\mathrm{WDM}}>2$ keV. All simulations form similar stellar discs independent of WDM particle mass. In particular, the disc scale length does not change when WDM is considered. The reduced amount of star formation in the case of 1 keV particles is due to the effects of WDM on merging satellites which are on average less concentrated and less gas rich. The altered satellites cause a reduced starburst during mergers because they trigger weaker disc instabilities in the main galaxy. Nevertheless we show that disc galaxy evolution is much more sensitive to stellar feedback than it is to WDM candidate mass. Overall we find that WDM, especially when restricted to current observational constraints ($m_{\mathrm{WDM}}>2$ keV), has a minor impact on disc galaxy formation.Comment: 13 pages, 9 figures, 2 tables; minor clarifications added in results section, conclusions unchanged; accepted for publication in MNRA

Intrinsic Transverse Size Effect

Two recently proposed concepts to improve the perturbative calculation of exclusive amplitudes, gluonic radiative corrections (Sudakov factor) and confinement size effects (intrinsic transverse momentum) are combined to study the neutron magnetic form factor in the space-like region. We find that nucleon distribution amplitudes modelled on the basis of current QCD sum rules indicate overlap with the existing data at the highest measured values of momentum transfer. However, sizeable higher-order perturbative corrections (K-factor) and/or higher-twist contributions cannot be excluded, although they may be weaker than in the proton case.Comment: 12 pages LATEX, 4 figures as compressed uu-encoded PS-file, preprint University of Wuppertal WU-B-94-16, University of Bochum RUB-TPII-04/94 (some typos eliminated