Structural and electronic properties of Si/Ge nanoparticles

Results of a theoretical study of the electronic properties of (Si)Ge and (Ge)Si core/shell nanoparticles, homogeneous SiGe clusters, and Ge$|$Si clusters with an interphase separating the Si and Ge atoms are presented. In general, (Si)Ge particles are more stable than (Ge)Si ones, and SiGe systems are more stable than Ge$|$Si ones. It is found that the frontier orbitals, that dictate the optical properties, are localized to the surface, meaning that saturating dangling bonds on the surface with ligands may influence the optical properties significantly. In the central parts we identify a weak tendency for the Si atoms to accept electrons, whereas Ge atoms donate electrons.Comment: To appear in Phys. Rev.

Das Amerikanische Arbeitsrecht aus der Perspektive Historischer und Zukünftiger Entwicklungen

In den vergangenen 15 Jahren ließen sich im amerikanischen Kollektiv- und Individualarbeitsrecht sowohl eine Fortsetzung der früheren Trends als auch die Entstehung neuer Themenfelder beobachten.Das System des kollektiven Arbeitsrechts, das die gewerkschaftliche Interessenvertretung und die Beziehungen zwischen den Beschäftigten und dem Management regelt, hat sich in seiner grundlegenden, auf die Zeit der Great Depression und die Jahre unmittelbar nach dem Zweiten Weltkrieg zurückgehenden Rechtsstruktur kaum verändert. Das amerikanische Individualarbeitsrecht hat dagegen mit der Einführung zusätzlicher individueller Arbeitnehmerrechte eine beträchtliche Dynamik entwickelt. Die Veränderungen in der Arbeitsorganisation und die Entwicklung neuer Formen von Arbeitsverträgen bedeuten eine zusätzliche Herausforderung für die traditionelle Sicht der Arbeitsbeziehungen, auf denen ein beträchtlicher Teil des amerikanischen Arbeitsrechts basiert. Schließlich wurden auch durch den Globalisierungsprozess und den Beitritt der Vereinigten Staaten zu neuen Handelsabkommen neue arbeitsrechtliche Fragen aufgeworfen.Durch diese Entwicklungen ergeben sich große Probleme für die derzeitige, im amerikanischen Arbeitsrecht verankerte, Struktur der kollektiven Interessenvertretung

On the equation of state of a dense columnar liquid crystal

An accurate description of a columnar liquid crystal of hard disks at high packing fractions is presented using an improved free-volume theory. It is shown that the orientational entropy of the disks in the one-dimensional fluid direction leads to a different high-density scaling pressure compared to the prediction from traditional cell theory. Excellent quantitative agreement is found with recent Monte-Carlo simulation results for various thermodynamic and structural properties of the columnar state.Comment: 4 pages, 2 figures, to appear in Phys. Rev. Let

Faster linearizability checking via PP-compositionality

Linearizability is a well-established consistency and correctness criterion for concurrent data types. An important feature of linearizability is Herlihy and Wing's locality principle, which says that a concurrent system is linearizable if and only if all of its constituent parts (so-called objects) are linearizable. This paper presents $P$-compositionality, which generalizes the idea behind the locality principle to operations on the same concurrent data type. We implement $P$-compositionality in a novel linearizability checker. Our experiments with over nine implementations of concurrent sets, including Intel's TBB library, show that our linearizability checker is one order of magnitude faster and/or more space efficient than the state-of-the-art algorithm.Comment: 15 pages, 2 figure

Identification and evaluation of suitable reference genes for gene expression studies in the whitefly Bemisia tabaci (Asia I) by reverse transcription quantitative realtime PCR

This study presents a reliable method for performing reverse transcription quantitative realtime PCR (RT-qPCR) to measure gene expression in the whitefly Bemisia tabaci (Asia I) (Gennadius) (Hemiptera: Aleyrodidae), utilising suitable reference genes for data normalisation. We identified orthologs of commonly used reference genes (actin (ACT), cyclophilin 1 (CYP1), elongation factor 1α (EF1A), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), ribosomal protein L13a (RPL13A), and α-tubulin (TUB1A)), measured the levels of their transcripts by RT-qPCR during development and in response to thermal stress, and evaluated their suitability as endogenous controls using geNorm, BestKeeper, and NormFinder programs. Overall, TUB1A, RPL13A, and CYP1 were the most stable reference genes during B. tabaci development, and TUB1A, GAPDH, and RPL13A were the most stable reference genes in the context of thermal stress. An analysis of the effects of reference gene choice on the transcript profile of a developmentally-regulated gene encoding vitellogenin demonstrated the importance of selecting the correct endogenous controls for RT-qPCR studies. We propose the use of TUB1A, RPL13A, and CYP1 as endogenous controls for transcript profiling studies of B. tabaci development, whereas the combination of TUB1A, GAPDH, and RPL13A should be employed for studies into thermal stress. The data pre- sented here will assist future transcript profiling studies in whiteflies

Nonvascularized human skin chronic allograft rejection.

A 65-year-old man had extensive burns of the lower legs in 1991, at the age of 40 years. He was treated by nonvascularized and de-epithelialized, allogeneic split-thickness skin allograft and cyclosporine monotherapy for 2 months. Ulcers developed between 10 and 25 years after transplantation and a surgical debridement on the lower extremities was required. Analyses of the removed tissue allografts showed chronic antibody-mediated and cellular rejection with extensive and dense fibrosis, and diffuse capillary C4d deposits. An anti-DRB1*08:01, donor-specific antibody was present. A unique clinical condition with late immunopathological features of human skin chronic allograft rejection is reported

Transient x-ray diffraction used to diagnose shock compressed Si crystals on the Nova laser

Transient x-ray diffraction is used to record time-resolved information about the shock compression of materials. This technique has been applied on Nova shock experiments driven using a hohlraum x-ray drive. Data were recorded from the shock release at the free surface of a Si crystal, as well as from Si at an embedded ablator/Si interface. Modeling has been done to simulate the diffraction data incorporating the strained crystal rocking curves and Bragg diffraction efficiencies. Examples of the data and post-processed simulations are presented

Photothermal Absorption Spectroscopy of Individual Semiconductor Nanocrystals

Photothermal heterodyne detection is used to record the first room-temperature absorption spectra of single CdSe/ZnS semiconductor nanocrystals. These spectra are recorded in the high cw excitation regime, and the observed bands are assigned to transitions involving biexciton and trion states. Comparison with the single nanocrystals photoluminescence spectra leads to the measurement of spectral Stokes shifts free from ensemble averaging