Magnetoelectric properties of 500 nm Cr2O3 films

The linear magnetoelectric effect was measured in 500 nm Cr2O3 films grown by rf sputtering on Al2O3 substrates between top and bottom thin film Pt electrodes. Magnetoelectric susceptibility was measured directly by applying an AC electric field and measuring the induced AC magnetic moment using superconducting quantum interference device magnetometry. A linear dependence of the induced AC magnetic moment on the AC electric field amplitude was found. The temperature dependence of the magnetoelectric susceptibility agreed qualitatively and quantitatively with prior measurements of bulk single crystals, but the characteristic temperatures of the film were lower than those of single crystals. It was also possible to reverse the sign of the magnetoelectric susceptibility by reversing the sign of the magnetic field applied during cooling through the N\'eel temperature. A competition between total magnetoelectric and Zeeman energies is proposed to explain the difference between film and bulk Cr2O3 regarding the cooling field dependence of the magnetoelectric effect.Comment: accepted at Physical Review

Is \lq\lq Heavy Quark Damping Rate Puzzle'' in Hot QCD Really the Puzzle?

Within the framework of perturbative resummation scheme of Pisarski and Braaten, the decay- or damping-rate of a moving heavy quark (muon) to leading order in weak coupling in hot QCD (QED) is examined. Although, as is well known, the conventionally-defined damping rate diverges logarithmically at the infrared limit, shown is that no such divergence appears in the physically measurable decay rate. The cancellation occurs between the contribution from the \lq\lq real'' decay diagram and the contribution from the diagrams with \lq\lq thermal radiative correction''.Comment: 13pages, OCU-PHYS-15

Finite-temperature reaction-rate formula: Finite volume system, detailed balance, T→0T \to 0 limit, and cutting rules

A complete derivation, from first principles, of the reaction-rate formula for a generic process taking place in a heat bath of finite volume is given. It is shown that the formula involves no finite-volume correction. Through perturbative diagrammatic analysis of the resultant formula, the detailed-balance formula is derived. The zero-temperature limit of the formula is discussed. Thermal cutting rules, which are introduced in previous work, are compared with those introduced by other authors.Comment: 35pages (text) plus 4pages (figures

Dimensionality dependence of optical nonlinearity and relaxation dynamics in cuprates

Femtosecond pump-probe measurements find pronounced dimensionality dependence of the optical nonlinearity in cuprates. Although the coherent two-photon absorption (TPA) and linear absorption bands nearly overlap in both quasi-one and two-dimensional (1D and 2D) cuprates, the TPA coefficient is one order of magnitude smaller in 2D than in 1D. Furthermore, picosecond recovery of optical transparency is observed in 1D cuprates, while the recovery in 2D involves relaxation channels with a time scales of tens of picoseconds. The experimental results are interpreted within the two-band extended Hubbard model.Comment: 10 pages, 4 figure

Different mechanics of snap-trapping in the two closely related carnivorous plants Dionaea muscipula and Aldrovanda vesiculosa

The carnivorous aquatic Waterwheel Plant (Aldrovanda vesiculosa L.) and the closely related terrestrial Venus Flytrap (Dionaea muscipula SOL. EX J. ELLIS) both feature elaborate snap-traps, which shut after reception of an external mechanical stimulus by prey animals. Traditionally, Aldrovanda is considered as a miniature, aquatic Dionaea, an assumption which was already established by Charles Darwin. However, videos of snapping traps from both species suggest completely different closure mechanisms. Indeed, the well-described snapping mechanism in Dionaea comprises abrupt curvature inversion of the two trap lobes, while the closing movement in Aldrovanda involves deformation of the trap midrib but not of the lobes, which do not change curvature. In this paper, we present the first detailed mechanical models for these plants, which are based on the theory of thin solid membranes and explain this difference by showing that the fast snapping of Aldrovanda is due to kinematic amplification of the bending deformation of the midrib, while that of Dionaea unambiguously relies on the buckling instability that affects the two lobes.Comment: accepted in Physical Review

PCR-based Landmark Unique Gene (PLUG) markers are a useful tool for comparative genomic analysis and BAC clone screening in wheat

Dissertação de mestrado em Psicologia Clínica e Saúde (Psicopatologia e Psicoterapia Dinâmica), apresentada à Faculdade de Psicologia e Ciências da Educação da Universidade de CoimbraOs pacientes infetados pelo VIH têm sido objeto de interesse por parte dos profissionais de saúde mental pela dimensão do impacto psicológico do diagnóstico, evolução da infeção e a vulnerabilidade destes sujeitos. Seja como for, em traço de evolução da terapêutica, a infeção pelo vírus da imunodeficiência humana (VIH) é, atualmente, uma doença tendencialmente crónica. Entre as perturbações mentais, a depressão é descrita como uma das comorbidades mais frequentes nos indivíduos com VIH e que muitas vezes passa despercebida. Acompanha-se de elevada morbilidade e apresenta um impacto sócio-económico, sendo uma das causas mais frequentes de suicídio. Para além da incapacidade que se vai instalando progressivamente, os indivíduos são confrontados com o estigma social, carência de apoio social e isolamento. Neste sentido, este estudo foi realizado com o intuito de chamar a atenção para a necessidade de intervenção psicoterapêutica com esta população, através da exploração dos sintomas psicopatológicos mais prevalentes (com especial destaque para a depressão e para a ideação suicida), tendo em consideração a progressão da doença e a as caraterísticas socio-demográficas.Patients infected with HIV have been the object of interest on the part of mental health professionals due to the dimension of the psychological impact of the diagnosis, the course of infection and the vulnerability of these subjects. Anyway, in trait evolution of therapy, infection by the human immunodeficiency virus (HIV) is currently a chronic disease. Among mental disorders, depression is described as one of the most frequent comorbidities in individuals infected with HIV and which often goes unnoticed. It is accompanied by high morbidity and presents a socialeconomic impact, being one of the most frequent causes of suicide. Beyond the progressively established disability, individuals face social stigma, lack of social support and isolation. Thus, this study was conducted in order to draw attention to the need for psychotherapeutic intervention among this population, through the exploitation of the most prevalent psychopathological symptoms (with special emphasis on depression and suicidal ideation), taking into account the progression of this disease and the social-demographic characteristics

Pathological activation of KIT in metastatic tumors of acral and mucosal melanomas

ArticleINTERNATIONAL JOURNAL OF CANCER. 124(4):862-868 (2009)journal articl