Glass transition of binary mixtures of dipolar particles in two dimensions

We study the glass transition of binary mixtures of dipolar particles in two dimensions within the framework of mode-coupling theory, focusing in particular on the influence of composition changes. In a first step, we demonstrate that the experimental system of K\"onig et al. [Eur. Phys. J. E 18, 287 (2005)] is well described by point dipoles through a comparison between the experimental partial structure factors and those from our Monte Carlo simulation. For such a mixture of point particles we show that there is always a plasticization effect, i.e. a stabilization of the liquid state due to mixing, in contrast to binary hard disks. We demonstrate that the predicted plasticization effect is in qualitative agreement with experimental results. Furthermore, also some general properties of the glass transition lines are discussed.Comment: 12 pages, 8 figures, J. Non-Cryst. Solids (in print

Global Militarisation Index: presentation, codebook and reflexion

Measuring militarisation is complex. Since 2003 and retrospectively up to 1990, BICC has been measuring militarisation worldwide with the Global Militarisation Index (GMI). The GMI’s approach is resource-based and measures the level of militarisation of a society by its allocation of resources by the state to the military in relation with other areas of society. By measuring the level of militarisation and the resulting time series annually, processes of militarisation or demilitarisation of societies and regions can be mapped. In this Working Paper, for the first time, the authors present the Codebook which underpins the GMI. They also discuss the current methodology and possible additions in view of the changing framework conditions and new data sources. In particular, they discuss the inclusion of novel weapons systems but also the vision of a multi-dimensional concept of militarisation

Contacting a single nanometer-sized pinhole in the interfacial oxide of a poly-silicon on oxide (POLO) solar cell junction

The electrical current through poly-Si on oxide (POLO) solar cells is mediated by tunneling and by nanometer-sized pinholes in the interfacial oxide. To distinguish the two processes, a POLO junction with a measured pinhole density of 1 × 107 cm−2 is contacted by different contact areas ranging from 1 μm2 to 2.5 × 105 μm2, and the temperature-dependent current–voltage curves are measured for the different devices. Model regressions to the measured curves, their temperature dependence, and the quantized value of contact resistances indicate average numbers of pinholes per device corresponding to the expected pinhole density. For the small contacts, the different transport processes can be studied separately, which facilitates further improvements in respect to the present-day POLO junctions. Single-pinhole transport is found for one of the contacts with an area of 1 μm2. Random telegraph noise observed for this device in the current–voltage characteristics shows a high sensitivity to single charges

Temperature-dependent broadening of coherent current peaks in InAs double quantum dots

Quantum systems as used for quantum computation or quantum sensing are nowadays often realized in solid state devices as e.g. complex Josephson circuits or coupled quantum-dot systems. Condensed matter as an environment influences heavily the quantum coherence of such systems. Here, we investigate electron transport through asymmetrically coupled InAs double quantum dots and observe an extremely strong temperature dependence of the coherent current peaks of single-electron tunneling. We analyze experimentally and theoretically the broadening of such coherent current peaks up to temperatures of 20K and we are able to model it with quantum dissipation being due to two different bosonic baths. These bosonic baths mainly originate from substrate phonons. Application of a magnetic field helps us to identify the different quantum dot states through their temperature dependence

Globaler Militarisierungsindex: Vorstellung, Codebook und Reflexion

Die Messung von Militarisierung ist ein komplexes Unterfangen. Seit 2003 und rückwirkend bis 1990 misst das BICC über den Globalen Militarisierungsindex (GMI) Militarisierung weltweit. Der GMI verfolgt einen ressourcenzentrierten Ansatz, der den Militarisierungsgrad einer Gesellschaft über die Ressourcenzuweisung von Seiten des Staates an das Militär relational zu anderen Gesellschaftsbereichen misst. Über die jährliche Messung des Militarisierungsgrades und die dadurch entstehenden Zeitreihen lassen sich Prozesse der Militarisierung bzw. Demilitarisierung von Gesellschaften und Regionen abbilden. Das vorliegende Working Paper stellt den Index anhand seines Codebooks erstmals vor und diskutiert sowohl die aktuelle Methodik als auch mögliche Ergänzungen angesichts sich verändernder Rahmenbedingungen und neuer Datenquellen. Dabei wird insbesondere die Aufnahme neuer Waffensysteme, aber auch die Entwicklung eines multidimensionalen Konzeptes von Militarisierung diskutiert

Towards Solving QCD in Light-Cone Quantization -- On the Spectrum of the Transverse Zero Modes for SU(2)

The formalism for a non-abelian pure gauge theory in (2+1) dimensions has recently been derived within Discretized Light-Cone Quantization, restricting to the lowest {\it transverse} momentum gluons. It is argued why this model can be a paradigm for full QCD. The physical vacuum becomes non-trivial even in light-cone quantization. The approach is brought here to tractable form by suppressing by hand both the dynamical gauge and the constraint zero mode, and by performing a Tamm-Dancoff type Fock-space truncation. Within that model the Hamiltonian is diagonalized numerically, yielding mass spectra and wavefunctions of the glue-ball states. We find that only color singlets have a stable and discrete bound state spectrum. The connection with confinement is discussed. The structure function of the gluons has a shape like $[{x(1-x)}] ^{1\over 3}$. The existence of the continuum limit is verified by deriving a coupled set of integral equations.Comment: 1 Latex file & 9 Postscript files; tarred, compressed and uuencode

Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times $10^{-22}$.Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 200