Inflammatory bowel disease-specific autoantibodies in HLA-B27-associated spondyloarthropathies: Increased prevalence of ASCA and pANCA

Aims: An association between inflammatory bowel disease (IBD) and spondyloarthropathies (SpA) has repeatedly been reported. The aim of the present study was to investigate whether serologic markers of IBD, e. g. antibodies against Saccharomyces cerevisiae (ASCA), antibodies against exocrine pancreas (PAB) and perinuclear antineutrophil cytoplasmic antibodies (pANCA) are present in HLA-B27-associated SpA. Methods: 87 patients with HLA-B27-positive SpA and 145 controls were tested for ASCA, PAB and pANCA employing ELISA or indirect immunofluorescence, respectively. Antibody-positive patients were interviewed regarding IBD-related symptoms using a standardized questionnaire. Results/Conclusion: When compared to the controls, ASCA IgA but not ASCA IgG levels were significantly increased in patients with SpA, in particular in ankylosing spondylitis (AS) and undifferentiated SpA (uSpA). pANCA were found in increased frequency in patients with SpA whereas PAB were not detected. The existence of autoantibodies was not associated with gastrointestinal symptoms but sustains the presence of a pathophysiological link between bowel inflammation and SpA. Copyright (C) 2004 S. Karger AG, Basel

Insulator, semiclassical oscillations and quantum Hall liquids at low magnetic fields

Magneto-transport measurements are performed on two-dimensional GaAs electron systems to probe the quantum Hall (QH) effect at low magnetic fields. Oscillations following the Shubnikov-de Haas (SdH) formula are observed in the transition from the insulator to QH liquid when the observed almost temperature-independent Hall slope indicates insignificant interaction correction. Our study shows that the existence of SdH oscillations in such a transition can be understood based on the non-interacting model.Comment: 17 page

Gain and Loss in Quantum Cascade Lasers

We report gain calculations for a quantum cascade laser using a fully self-consistent quantum mechanical approach based on the theory of nonequilibrium Green functions. Both the absolute value of the gain as well as the spectral position at threshold are in excellent agreement with experimental findings for T=77 K. The gain strongly decreases with temperature.Comment: 7 pages, 3 figures directly include

Шляхи підвищення ефективності фінансово-господарської діяльності підприємства

Мета даної статті полягає в необхідності виробити заходи з підвищення ефективності фінансово-господарської діяльності підприємства (на прикладі Кримського республіканського підприємства «Виробниче підприємство водопровідно-каналізаційної галузі» м. Сімферополя)

Magnetic control of Coulomb scattering and terahertz transitions among excitons

Time-resolved terahertz quenching studies of the magnetoexcitonic photoluminescence from GaAs/AlGaAs quantum wells are performed. A microscopic theory is developed to analyze the experiments. Detailed experiment-theory comparisons reveal a remarkable magnetic-field controllability of the Coulomb and terahertz interactions in the excitonic system.Comment: 5 pages, 4 figure

Terahertz dynamics of a topologically protected state: quantum Hall effect plateaus near cyclotron resonance in a GaAs/AlGaAs heterojunction

We measure the Hall conductivity of a two-dimensional electron gas formed at a GaAs/AlGaAs heterojunction in the terahertz regime close to the cyclotron resonance frequency by employing a highly sensitive Faraday rotation method coupled with electrical gating of the sample to change the electron density. We observe clear plateau-and step-like features in the Faraday rotation angle vs. electron density and magnetic field (Landau-level filling factor), which are the high frequency manifestation of quantum Hall plateaus - a signature of topologically protected edge states. The results are compared to a recent dynamical scaling theory.Comment: 18 pages, 3 figure

Valence band photoemission from the GaN(0001) surface

A detailed investigation by one-step photoemission calculations of the GaN(0001)-(1x1) surface in comparison with recent experiments is presented in order to clarify its structural properties and electronic structure. The discussion of normal and off-normal spectra reveals through the identified surface states clear fingerprints for the applicability of a surface model proposed by Smith et al. Especially the predicted metallic bonds are confirmed. In the context of direct transitions the calculated spectra allow to determine the valence band width and to argue in favor of one of two theoretical bulk band structures. Furthermore a commonly used experimental method to fix the valence band maximum is critically tested.Comment: 8 pages, 11 eps files, submitted to PR

Historical-institutionalist perspectives on the development of the EU budget system

The EU budget has only recently started to feature in theories of European integration. Studies typically adopt a historical-institutionalist framework, exploring notions such as path dependency. They have, however, generally been rather aggregated, or coarse-grained, in their approach. The EU budget has thus been treated as a single entity rather than a series of inter-linked institutions. This paper seeks to address these lacunae by adopting a fine-grained approach. This enables us to emphasize the connections that exist between EU budgetary institutions, in both time and space. We show that the initial set of budgetary institutions was unable, over time, to achieve consistently their treaty-based objectives. In response, rather than reform these institutions at potentially high political cost, additional institutions were layered on top of the extant structures. We thus demonstrate how some EU budgetary institutions have remained unchanged, whilst others have been added or changed over time