703 research outputs found
Finite-size effects in the superconformal beta-deformed N=4 SYM
We study finite size effects for composite operators in the SU(2) sector of
the superconformal beta-deformed N=4 SYM theory. In particular we concentrate
on the spectrum of one single magnon. Since in this theory one-impurity states
are non BPS we compute their anomalous dimensions including wrapping
contributions up to four loops and discuss higher order effects.Comment: LaTeX, mpost, feynmf, 20 pages, 4 figures, 5 tables; v2: references
added, equations (4.13) and (4.17) correcte
Desorption Dynamics of Heavy Alkali Metal Atoms (Rb, Cs) off the Surface of Helium Nanodroplets
We present a combined ion imaging and density functional theory study of the
dynamics of the desorption process of rubidium and cesium atoms off the surface
of helium nanodroplets upon excitation of the perturbed and states,
respectively. Both experimental and theoretical results are well represented by
the pseudodiatomic model for effective masses of the helium droplet in the
desorption reaction of m_eff/m_He~10 (Rb) and 13 (Cs). Deviations from this
model are found for Rb excited to the 6p state. Photoelectron spectra indicate
that the dopant-droplet interaction induces relaxation into low-lying
electronic states of the desorbed atoms in the course of the ejection process.Comment: in press, J. Phys. Chem. A (2014
Signaling through focal adhesion kinase
Integrin receptor binding to extracellular matrix proteins generates intracellular signals via enhanced tyrosine phosphorylation events that are important for cell growth, survival, and migration. This review will focus on the functions of the focal adhesion kinase (FAK) protein-tyrosine kinase (PTK) and its role in linking integrin receptors to intracellular signaling pathways. FAK associates with several di€erent signaling proteins such as Src-family PTKs, p130 Cas, Shc, Grb2, PI 3-kinase, and paxillin. This enables FAK to function within a network of integrin-stimulated signaling pathways leading to the activation of targets such as the ERK and JNK/mitogen-activated protein kinase pathways. Focus will be placed on the structural domains and sites of FAK tyrosine phosphorylation important for FAKmediated signaling events and how these sites are conserved in the FAK-related PTK, Pyk2. We will review what is known about FAK activation by integrin receptor-mediated events and also non-integrin stimuli. In addition, we discuss the emergence of a consensus FAK substrate phosphorylation sequence. Emphasis will also be placed on the role of FAK in generating cell survival signals and the cleavage of FAK during caspase-mediated apoptosis. An in-depth discussion will be presented of integrin-stimulated signaling events occurring in the FAK knockout ®broblasts (FAK � ) and how these cells exhibit de®cit
Conformal boundary and geodesics for and the plane wave: Their approach in the Penrose limit
Projecting on a suitable subset of coordinates, a picture is constructed in
which the conformal boundary of and that of the plane wave
resulting in the Penrose limit are located at the same line. In a second line
of arguments all and plane wave geodesics are constructed in
their integrated form. Performing the Penrose limit, the approach of null
geodesics reaching the conformal boundary of to that of the
plane wave is studied in detail. At each point these null geodesics of
form a cone which degenerates in the limit.Comment: some statements refined, chapter 5 rewritten to make it more precise,
some typos correcte
Ellipsometric study of InGaAs MODFET material
In(x)Ga(1-x)As based MODFET (modulation doped field effect transistor) material was grown by molecular beam epitaxy on semi-insulating InP substrates. Several structures were made, including lattice matched and strained layer InGaAs. All structures also included several layers of In(0.52)Al(0.48)As. Variable angle spectroscopic ellipsometry was used to characterize the structures. The experimental data, together with the calibration function for the constituent materials, were analyzed to yield the thickness of all the layers of the MODFET structure. Results of the ellipsometrically determined thicknesses compare very well with the reflection high energy electron diffraction in situ thickness measurements
Plasticity of Acquired Secondary Metabolites in Clathria prolifera (Demospongia: Poecilosclerida): Putative Photoprotective Role of Carotenoids in a Temperate Intertidal Sponge
Several marine sponges sequester high concentrations of carotenoids in their tissues. The diversity of carotenoid compounds has been described in detail for a handful of species, but to date, little attention has been paid to natural variability in the concentration and constituency of carotenoid pools. Also lacking are experimental tests of some of the proposed adaptive benefits of carotenoids to the sponge. To address some of these deficits in our understanding of sponge ecology, we used a combination of analytic chemistry, field surveys, and manipulative experiments to determine what function these compounds might play. Attention was focused on the common, carotenoid-rich intertidal sponge Clathria (Microciona) prolifera from Chesapeake Bay, Virginia, USA. Surveys of pier pilings indicated that C. prolifera was most common towards the surface of the water, with an average depth of 1 m, and also occurred most frequently on pilings exposed to sunlight. Total carotenoid concentrations (as estimated from spectroscopy) were maximal when solar radiation was nearing its northern maximum. However, HPLC analysis of crude acetone extracts highlighted several instances where concentrations of individual putative carotenoids were maximal during thermal (not solar) maxima in Chesapeake Bay. Naturally occurring sponges growing in environments protected from direct sunlight were found to have significantly lower total carotenoid concentration. In a manipulative field experiment, sponges transplanted from exposed habitats to shaded habitats showed significant decreases in carotenoid concentrations. HPLC analysis demonstrated that concentrations for several of the pigmented compounds decreased under reduced light levels. Given that sponges do not produce carotenoids de novo, the ecological role that these compounds play in sponge physiology deserves greater attention. Our findings indicate that solar radiation is an important factor in shaping carotenoid profiles of C. prolifera. While the physiological role and ultimate source of these compounds remains unclear, our data point to an adaptive function and indicate that C. prolifera is a useful species to address these questions
Postoperative Anaemia Might Be a Risk Factor for Postoperative Delirium and Prolonged Hospital Stay: A Secondary Analysis of a Prospective Cohort Study
Background: Postoperative anaemia is a frequent surgical complication and in contrast to preoperative anaemia has not been validated in relation to mortality, morbidity and its associated health economic effect. Postoperative anaemia can predispose postoperative delirium through impairment of cerebral oxygenation. The aim of this secondary analysis is to investigate the association of postoperative anaemia in accordance with the sex specific World Health Organization definition of anaemia to postoperative delirium and its impact on the duration of hospital stay.
Methods: A secondary analysis of the prospective multicentric observational CESARO-study was conducted. 800 adult patients undergoing elective surgery were enrolled from various operative disciplines across seven hospitals ranging from university hospitals, district general hospitals to specialist clinics of minimally invasive surgery in Germany. Patients were classified as anaemic according to the World Health Organization parameters, setting the haemoglobin level cut off below 12g/dl for females and below 13g/dl for males. Focus of the investigation were patients with acute anaemia. Patients with present preoperative anaemia or missing haemoglobin measurement were excluded from the sample set. Delirium screening was established postoperatively for at least 24 hours and up to three days, applying the validated Nursing Delirium Screening Scale.
Results: The initial sample set contained 800 patients of which 183 were suitable for analysis in the study. Ninety out of 183 (49.2%) suffered from postoperative anaemia. Ten out of 93 (10.9%) patients without postoperative anaemia developed a postoperative delirium. In the group with postoperative anaemia, 28 (38.4%) out of 90 patients suffered from postoperative delirium (odds ratio 3.949, 95% confidence interval, (1.358-11.480)) after adjustment for NYHA-stadium, severity of surgery, cutting/suture time, duration of anaesthesia, transfusion of packed red cells and sedation status with Richmond Agitation Scale after surgery. Additionally, patients who suffered from postoperative anaemia showed a significantly longer duration of hospitalisation (7.75 vs. 12.42 days, odds ratio = 1.186, 95% confidence interval, 1.083-1.299, after adjustments).
Conclusion: The study results reveal that postoperative anaemia is not only a frequent postsurgical complication with an incidence probability of almost 50%, but could also be associated with a postoperative delirium and a prolonged hospitalisation
Dielectric function of InGaAs in the visible
Measurements are reported of the dielectric function of thermodynamically stable In(x)Ga(1-x)As in the composition range 0.3 equal to or less than X = to or less than 0.7. The optically thick samples of InGaAs were made by molecular beam epitaxy (MBE) in the range 0.4 = to or less than X = to or less than 0.7 and by metal-organic chemical vapor deposition (MOCVD) for X = 0.3. The MBE made samples, usually 1 micron thick, were grown on semi-insulating InP and included a strain release structure. The MOCVD sample was grown on GaAs and was 2 microns thick. The dielectric functions were measured by variable angle spectroscopic ellipsometry in the range 1.55 to 4.4 eV. The data was analyzed assuming an optically thick InGaAs material with an oxide layer on top. The thickness of this layer was estimated by comparing the results for the InP lattice matched material, i.e., X = 0.53, with results published in the literature. The top oxide layer mathematically for X = 0.3 and X = 0.53 was removed to get the dielectric function of the bare InGaAs. In addition, the dielectric function of GaAs in vacuum, after a protective arsenic layer was removed. The dielectric functions for X = 0, 0.3, and 0.53 together with the X = 1 result from the literature to evaluate an algorithm for calculating the dielectric function of InGaAs for an arbitrary value of X(0 = to or less than X = to or less than 1) were used. Results of the dielectric function calculated using the algorithm were compared with experimental data
Study of InGaAs based MODFET structures using variable angle spectroscopic ellipsometry
Variable angle spectroscopic ellipsometry was used to estimate the thicknesses of all layers within the optical penetration depth of InGaAs based MODFET structures. Strained and unstrained InGaAs channels were made by MBE on InP substrates and by MOCVD on GaAs substrates. In most cases, ellipsometrically determined thicknesses were within 10 percent of the growth calibration results. The MBE made InGaAs strained layers showed large strain effects, indicating a probable shift in the critical points of their dielectric function toward the InP lattice matched concentration
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