Variational solution of the T-matrix integral equation

We present a variational solution of the T-matrix integral equation within a local approximation. This solution provides a simple form for the T matrix similar to Hubbard models but with the local interaction depending on momentum and frequency. By examining the ladder diagrams for irreducible polarizability, a connection between this interaction and the local-field factor is established. Based on the obtained solution, a form for the T-matrix contribution to the electron self-energy in addition to the GW term is proposed. In the case of the electron-hole multiple scattering, this form allows one to avoid double counting.Comment: 7 pages, 7 figure

Optical properties and one-particle spectral function in non-ideal plasmas

A basic concept to calculate physical features of non-ideal plasmas, such as optical properties, is the spectral function which is linked to the self-energy. We calculate the spectral function for a non-relativistic hydrogen plasma in $GW$-approximation. In order to go beyond $GW$ approximation, we include self-energy and vertex correction to the polarization function in lowest order. Partial compensation is observed. The relation of our approach to $GW$ and $GW\Gamma$ calculations in other fields, such as the band-structure calculations in semiconductor physics, is discussed. From the spectral function we derive the absorption coefficient due to inverse bremsstrahlung via the polarization function. As a result, a significant reduction of the absorption as compared to the Bethe-Heitler formula for bremsstrahlung is obtained.Comment: 13 pages, 7 figures, 52 references. Submitted to Contrib. Plasma Phys. Results presented at the International Workshop on Physics of Non-ideal Plasmas (PNP12), Darmstadt, sept. 4.-8. 200

Analytic structure factors and pair-correlation functions for the unpolarized homogeneous electron gas

We propose a simple and accurate model for the electron static structure factors (and corresponding pair-correlation functions) of the 3D unpolarized homogeneous electron gas. Our spin-resolved pair-correlation function is built up with a combination of analytic constraints and fitting procedures to quantum Monte Carlo data, and, in comparison to previous attempts (i) fulfills more known integral and differential properties of the exact pair-correlation function, (ii) is analytic both in real and in reciprocal space, and (iii) accurately interpolates the newest, extensive diffusion-Monte Carlo data of Ortiz, Harris and Ballone [Phys. Rev. Lett. 82, 5317 (1999)]. This can be of interest for the study of electron correlations of real materials and for the construction of new exchange and correlation energy density functionals.Comment: 14 pages, 5 figures, submitted to Phys. Rev.

Density functional theories and self-energy approaches

A purpose-designed microarray platform (Stressgenes, Phase 1) was utilised to investigate the changes in gene expression within the liver of rainbow trout during exposure to a prolonged period of confinement. Tissue and blood samples were collected from trout at intervals up to 648 h after transfer to a standardised confinement stressor, together with matched samples from undisturbed control fish. Plasma ACTH, cortisol, glucose and lactate were analysed to confirm that the neuroendocrine response to confinement was consistent with previous findings and to provide a phenotypic context to assist interpretation of gene expression data. Liver samples for suppression subtractive hybridisation (SSH) library construction were selected from within the experimental groups comprising “early” stress (2–48 h) and “late” stress (96–504 h). In order to reduce redundancy within the four SSH libraries and yield a higher number of unique clones an additional subtraction was carried out. After printing of the arrays a series of 55 hybridisations were executed to cover 6 time points. At 2 h, 6 h, 24 h, 168 h and 504 h 5 individual confined fish and 5 individual control fish were used with control fish only at 0 h. A preliminary list of 314 clones considered differentially regulated over the complete time course was generated by a combination of data analysis approaches and the most significant gene expression changes were found to occur during the 24 h to 168 h time period with a general approach to control levels by 504 h. Few changes in expression were apparent over the first 6 h. The list of genes whose expression was significantly altered comprised predominantly genes belonging to the biological process category (response to stimulus) and one cellular component category (extracellular region) and were dominated by so-called acute phase proteins. Analysis of the gene expression profile in liver tissue during confinement revealed a number of significant clusters. The major patterns comprised genes that were up-regulated at 24 h and beyond, the primary examples being haptoglobin, β-fibrinogen and EST10729. Two representative genes from each of the six k-means clusters were validated by qPCR. Correlations between microarray and qPCR expression patterns were significant for most of the genes tested. qPCR analysis revealed that haptoglobin expression was up-regulated approximately 8-fold at 24 h and over 13-fold by 168 h.This project was part funded by the European Commission (Q5RS-2001-02211), Enterprise Ireland and the Natural Environment Research Council of the United Kingdom

Thyroid function in Exhaustion Disorder: Higher prevalence of subclinical hypothyroidism

Title: Thyroid function in Exhaustion Disorder: Higher prevalence of subclinical hypothyroidism Author, Year: Christina Hindgren, 2012 Institution, City, County: Medicine, Gothenburg, Sweden Background: Exhaustion Disorder (ED) is a common illness characterized by reduced mental energy caused by stress. In order to increase understanding and improve treatments for the illness, research is needed to investigate its pathophysiology, including potential endocrine dysfunction. Aims: The general aims were to investigate if thyroid function is associated with ED and if there is a difference in thyroid function between patients with only ED and patients with Major Depression (MD) co-morbid to ED. Methods: The study was of a case-control, cross-sectional design. Thyroid function was assessed by measuring serum thyroid-stimulating hormone (TSH) and free thyroxine (fT4) in 350 ED patients and 200 controls. Results: There was no difference in TSH and fT4 between ED patients and healthy controls. Neither were there any differences in TSH and fT4 between the three groups ED with MD, ED without MD and controls. However, the prevalence of subclinical hypothyroidism was higher in ED patients compared to healthy controls. There was no difference between ED patients and controls in early thyroid failure defined as TSH above 2 mU/l. Conclusions: ED does not seem to be associated with thyroid dysfunction in general. However, subclinical hypothyroidism was more prevalent in ED patients compared with controls. ED patients with subclinical hypothyroidism may have started to develop thyroid failure prior or parallel to ED, which may have contributed to the symptoms seen in ED. Thus this could explanation the higher prevalence of subclinical hypothyroidism found in ED patients. It is also possible that subclinical hypothyroidism is a negative prognostic factor for treatment of ED. Future randomised controlled studies on treatment outcome is needed to clarify if ED patients with subclinical hypothyroidism will benefit from thyroid hormone therapy

Model Vertices Beyond the GW Approximation

We study the effects of local vertex corrections to the self energy of the electron gas. We find that a vertex derived from time-dependent density-functional theory can give accurate self energies without including the explicit time dependence of the exchange-correlation potential provided, however, that a proper decay at large momentum transfer (large q) is built into the vertex function. (The local-density approximation for the vertex fails badly.) Total energies are calculated from the Galitskii-Migdal formula and it is shown that a proper large-q behavior, results in a close consistency between the chemical potentials derived from these energies and those obtained directly from the self energy. We show that this internal consistency depends critically on including the same vertex correction in both the self-energy and the screening function. In addition the total energies become almost as accurate as those from elaborate quantum Monte-Carlo (QMC) calculations. We also study the accuracy and utility of the functional for the total energy proposed by Luttinger and Ward and a generalization by Almbladh, von Barth, and van Leeuwen. For the electron gas, even the simplest and readily evaluated approximations to these functionals yield total energies of similar quality as those of QMC calculations. The functionals depend on the one-electron Green's function and the screened Coulomb interaction and already rather crude approximations to these quantities produce accurate energies thus demonstrating the insensitivity of the functionals to their arguments. Different ways of incorporating vertex corrections beyond the $GW$ level are studied in simple, exactly soluble polaron-like models. We study models of a structureless core electron coupled to valence electrons and a local polaron model by Cini, Hewson and Newns. Our model results indicate that the first vertex correction alone will in general not suffice to improve the spectrum away from the quasi-particle peak. By including a subsequence of Mahan's fractal vertex series, however, we obtain results with correct physical properties which agree better with exact model results

ICDP International Child Development Programme Ett verktyg för specialpedagogens professionella rolltagande?

Hindgren, Lisbeth (2008). ICDP, International Child Development Programme Ett verktyg för specialpedagogens proffessionella rollragande? ICDP, International Child Development Programme A tool for the special educational needs teacher´s professional role? Examensarbete, Skolutveckling och ledarskap, Specialpedagogik, Lärarutbildningen, Malmö högskola. Syfte: Vad styr rolltagandet utifrån olika rollteoretiska perspektiv? Syftet med detta arbete är att undersöka om, och i så fall hur, det förhållningssätt som används inom ICDP/ vägledande samspel påverkar specialpedagogens rolltagande utifrån det specialpedagogiksa uppdraget i de olika arbetsområdena individ, grupp och organisation. Metod: Jag har valt att göra enkätundersökning bland tio inom ICDP/ Vägledande samspel utbildade specialpedagoger från olika kommuner. En motsvarande enkätundersökning görs bland tio obundet slumpvist utvalda specialpedagoger. Resultat: Resultatet visar att det finns en ökad medvetenhet hos specialpedagogerna inom studiegruppen att se betydelsen av samspel och interaktion som viktigt verktyg för lärandet hos barnet. Rolltagandet utgår från det systemteoretiska perspektivet. De visar också på en större medvetenhet och kompetens kring hur arbetsinsatserna bör fördelas utifrån vad som främjar det positiva samspelet mellan den vuxne och barnet. I likhet med min hypotes styrker resultatet i studien att ICDP vägledande samspels förhållningssätt påverkat och utvecklat specialpedagogens rolltagande i positiv riktning. Nyckelord: handledning, ICDP, specialpedagogens roll, verktyg Handledare Barbro Bruce, Examinator Lotta Anderso

Improved local-field corrections to the G_ {0} W approximation in jellium: Importance of consistency relations

We study the effects of local vertex corrections to the self-energy of the electron gas. We find that a vertex derived from time-dependent density-functional theory can give accurate self-energies, provided, however, a proper decay at large momentum transfer (large q) is built into the vertex function. (The local-density approximation for the vertex fails badly.) Total energies are calculated from the Galitskii-Migdal formula, and it is shown that a proper large-q behavior results in a close consistency between the chemical potentials derived from these energies and those obtained directly from the self-energy. We show that this internal consistency depends critically on including the same vertex correction in both the self-energy and the screening function. In addition the total energies become almost as accurate as those from elaborate Monte Carlo calculations. This as well as previous works show that self-energy corrections are important for properly describing electron propagation at energies around and above the plasmon energy. For easy use in calculations of photoemission and x-ray extended fine structure spectra, we parametrize our calculated self-energies in terms of a simple analytical expression

Livet efter förlusten, Traumatisk amputation ur ett patientperspektiv

I Sverige amputeras årligen cirka 2500 personer, merparten av dessa är benamputationer. Traumatiska amputationer är en av de mest kostsamma skadorna idag. Syftet med studien var att beskriva upplevelsen av att bli traumatiskt amputerad i en olycka eller efter en operation. Studien genomfördes som en litteraturstudie där 11 artiklar analyserades. Resultatet kategoriserades utifrån Cullbergs faser; chockfasen, reaktionsfasen, bearbetningsfasen och nyorienteringsfasen. En traumatisk amputation är en stor förändring, inte bara för den drabbade patienten utan även för närstående och vänner. Reaktioner efter amputationen var ilska, rädsla, osäkerhet och saknad av extremiteten. Patienterna upplevde att deras kroppsbild förändrades och att de var oförberedda på smärtan som kom efter amputationen. För de flesta patienterna var positivt tänkande, hopp och stöd från omgivningen viktigt för tillfrisknandet. Med protesens hjälp blev patienterna mer självständiga och självbilden förändrades till det positiva. Mer kvalitativ forskning om patientens upplevelse i samband med traumatisk amputation efterfrågas