Quasiparticle Corrections to the Electronic Properties of Anion Vacancies at GaAs(110) and InP(110)

We propose a new method for calculating optical defect levels and thermodynamic charge-transition levels of point defects in semiconductors, which includes quasiparticle corrections to the Kohn-Sham eigenvalues of density-functional theory. Its applicability is demonstrated for anion vacancies at the (110) surfaces of III-V semiconductors. We find the (+/0) charge-transition level to be 0.49 eV above the surface valence-band maximum for GaAs(110) and 0.82 eV for InP(110). The results show a clear improvement over the local-density approximation and agree closely with an experimental analysis.Comment: 4 pages including 1 figure, RevTe

COMPATIBILITY AND PROCESSING METHODS STUDY OF FORMULATION OF ARTEMETHER–LUMEFANTRINE FIXED DOSE COMBINATION USING ANALYTICAL TOOLS

ABSTRACTObjective: This study was undertaken to devise the best way to incorporate artemether-lumefantrine (AL) as model drugs during processing without compromising quality.Methods: Utilization of analytical tools revealed how compatibility of formulation components and suitability of process methods were monitored and controlled to achieve quality outcome.  Excipients of proven performance in wet granulation method as well as AL as model drugs were designed into six formulations coded F-1 to F-6 to reflect modes of incorporation. Physical mixtures and wet granulated samples at different levels of processing were screened as in-process materials for compatibility and method suitability using Fourier Transform Infrared (FTIR), Differential Scanning Calorimetry (DSC) and High Performance Liquid Chromatography (HPLC) techniques. Assessment of potential risks inherent in formulation and process unit operations was adequately addressed by these instruments.Results: Matching spectra, thermograms and chromatograms at different levels of processing indicated that there were no disappearance of old or appearance of new spectral bands; showed reduction of melting endotherm and similar characteristic elution times of AL as they transformed from pure material to physical mixture (PM) and to granules.Conclusion: Results from this work alluded to compatibility of formulation components and process method suitability to the extent that the resultant granulates were good enough for further processing

Two-Hole Bound States from a Systematic Low-Energy Effective Field Theory for Magnons and Holes in an Antiferromagnet

Identifying the correct low-energy effective theory for magnons and holes in an antiferromagnet has remained an open problem for a long time. In analogy to the effective theory for pions and nucleons in QCD, based on a symmetry analysis of Hubbard and t-J-type models, we construct a systematic low-energy effective field theory for magnons and holes located inside pockets centered at lattice momenta (\pm pi/2a,\pm pi/2a). The effective theory is based on a nonlinear realization of the spontaneously broken spin symmetry and makes model-independent universal predictions for the entire class of lightly doped antiferromagnetic precursors of high-temperature superconductors. The predictions of the effective theory are exact, order by order in a systematic low-energy expansion. We derive the one-magnon exchange potentials between two holes in an otherwise undoped system. Remarkably, in some cases the corresponding two-hole Schr\"odinger equations can even be solved analytically. The resulting bound states have d-wave characteristics. The ground state wave function of two holes residing in different hole pockets has a d_{x^2-y^2}-like symmetry, while for two holes in the same pocket the symmetry resembles d_{xy}.Comment: 35 pages, 11 figure

Characteristics of summer-time energy exchange in a high Arctic tundra heath 2000–2010

Global warming will bring about changes in surface energy balance of Arctic ecosystems, which will have implications for ecosystem structure and functioning, as well as for climate system feedback mechanisms. In this study, we present a unique, long-term (2000–2010) record of summer-time energy balance components (net radiation, R n; sensible heat flux, H; latent heat flux, LE; and soil heat flux, G) from a high Arctic tundra heath in Zackenberg, Northeast Greenland. This area has been subjected to strong summer-time warming with increasing active layer depths (ALD) during the last decades. We observe high energy partitioning into H, low partitioning into LE and high Bowen ratio (β=H/LE) compared with other Arctic sites, associated with local climatic conditions dominated by onshore winds, slender vegetation with low transpiration activity and relatively dry soils. Surface saturation vapour pressure deficit (D s) was found to be an important variable controlling within-year surface energy partitioning. Throughout the study period, we observe increasing H/R n and LE/R n and decreasing G/R n and β, related to increasing ALD and decreasing soil wetness. Thus, changes in summer-time surface energy balance partitioning in Arctic ecosystems may be of importance for the climate system

THE "FREELY" FALLING TWO-LEVEL ATOM IN A RUNNING LASER WAVE

The time evolution of a two-level atom which is simultaneously exposed to the field of a running laser wave and a homogeneous gravitational field is studied. The result of the coupled dynamics of internal transitions and center-of-mass motion is worked out exactly. Neglecting spontaneous emission and performing the rotating wave approximation we derive the complete time evolution operator in an algebraical way by using commutation relations. The result is discussed with respect to the physical implications. In particular the long time and short time behaviour is physically analyzed in detail. The breakdown of the Magnus perturbation expansion is shown.Comment: 14 Pages, Late

Implications of troponin testing in clinical medicine

During the past decade considerable research has been conducted into the use of cardiac troponins, their diagnostic capability and their potential to allow risk stratification in patients with acute chest pain. Determination of risk in patients with suspected myocardial ischaemia is known to be as important as retrospective confirmation of a diagnosis of myocardial infarction (MI). Therefore, creatine kinase (CK)-MB - the former 'gold standard' in detecting myocardial necrosis - has been supplanted by new, more accurate biomarkers.Measurement of cardiac troponin levels constitute a substantial determinant in assessment of ischaemic heart disease, the presentations of which range from silent ischaemia to acute MI. Under these conditions, troponin release is regarded as surrogate marker of thrombus formation and peripheral embolization, and therefore new therapeutic strategies are focusing on potent antithrombotic regimens to improve long-term outcomes. Although elevated troponin levels are highly sensitive and specific indicators of myocardial damage, they are not always reflective of acute ischaemic coronary artery disease; other processes have been identified that cause elevations in these biomarkers. However, because prognosis appears to be related to the presence of troponins regardless of the mechanism of myocardial damage, clinicians increasingly rely on troponin assays when formulating individual therapeutic plans