Electrical properties of CdTe near the melting point

A new experimental setup for the investigation of electrical conductivity (σ) in liquid and solid CdTe was built for a better understanding of the properties near the melting point (MP). The temperature dependence of σ was studied, within the interval 1,050-1,130°C, at defined Cd-partial pressures 1.3-1.6 atm, with special attention to the liquid-solid phase transition. We found that the degree of supercooling decreases with increasing Cd overpressure and reaches the lowest value at 1.6 atm without change of the melting temperature during heating

EPA guidance on the role and responsibilities of psychiatrists

Psychiatry is that branch of the medical profession, which deals with the origin, diagnosis, prevention, and management of mental disorders or mental illness, emotional and behavioural disturbances. Thus, a psychiatrist is a trained doctor who has received further training in the field of diagnosing and managing mental illnesses, mental disorders and emotional and behavioural disturbances. This EPA Guidance document was developed following consultation and literature searches as well as grey literature and was approved by the EPA Guidance Committee. The role and responsibilities of the psychiatrist include planning and delivering high quality services within the resources available and to advocate for the patients and the services. The European Psychiatric Association seeks to rise to the challenge of articulating these roles and responsibilities. This EPA Guidance is directed towards psychiatrists and the medical profession as a whole, towards other members of the multidisciplinary teams as well as to employers and other stakeholders such as policy makers and patients and their families

Reply to: New Meta- and Mega-analyses of Magnetic Resonance Imaging Findings in Schizophrenia: Do They Really Increase Our Knowledge About the Nature of the Disease Process?

This work was supported by National Institute of Biomedical Imaging and Bioengineering Grant No. U54EB020403 (to the ENIGMA consortium)

Increased power by harmonizing structural MRI site differences with the ComBat batch adjustment method in ENIGMA

A common limitation of neuroimaging studies is their small sample sizes. To overcome this hurdle, the Enhancing Neuro Imaging Genetics through Meta-Analysis (ENIGMA) Consortium combines neuroimaging data from many institutions worldwide. However, this introduces heterogeneity due to different scanning devices and sequences. ENIGMA projects commonly address this heterogeneity with random-effects meta-analysis or mixed-effects mega-analysis. Here we tested whether the batch adjustment method, ComBat, can further reduce site-related heterogeneity and thus increase statistical power. We conducted random-effects meta-analyses, mixed-effects mega-analyses and ComBat mega-analyses to compare cortical thickness, surface area and subcortical volumes between 2897 individuals with a diagnosis of schizophrenia and 3141 healthy controls from 33 sites. Specifically, we compared the imaging data between individuals with schizophrenia and healthy controls, covarying for age and sex. The use of ComBat substantially increased the statistical significance of the findings as compared to random-effects meta-analyses. The findings were more similar when comparing ComBat with mixed-effects mega-analysis, although ComBat still slightly increased the statistical significance. ComBat also showed increased statistical power when we repeated the analyses with fewer sites. Results were nearly identical when we applied the ComBat harmonization separately for cortical thickness, cortical surface area and subcortical volumes. Therefore, we recommend applying the ComBat function to attenuate potential effects of site in ENIGMA projects and other multi-site structural imaging work. We provide easy-to-use functions in R that work even if imaging data are partially missing in some brain regions, and they can be trained with one data set and then applied to another (a requirement for some analyses such as machine learning)

Cortical brain abnormalities in 4474 individuals with schizophrenia and 5098 control subjects via the enhancing neuro Imaging genetics through meta analysis (ENIGMA) Consortium

BACKGROUND: The profile of cortical neuroanatomical abnormalities in schizophrenia is not fully understood, despite hundreds of published structural brain imaging studies. This study presents the first meta-analysis of cortical thickness and surface area abnormalities in schizophrenia conducted by the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Schizophrenia Working Group. METHODS: The study included data from 4474 individuals with schizophrenia (mean age, 32.3 years; range, 11-78 years; 66% male) and 5098 healthy volunteers (mean age, 32.8 years; range, 10-87 years; 53% male) assessed with standardized methods at 39 centers worldwide. RESULTS: Compared with healthy volunteers, individuals with schizophrenia have widespread thinner cortex (left/right hemisphere: Cohen's d = -0.530/-0.516) and smaller surface area (left/right hemisphere: Cohen's d = -0.251/-0.254), with the largest effect sizes for both in frontal and temporal lobe regions. Regional group differences in cortical thickness remained significant when statistically controlling for global cortical thickness, suggesting regional specificity. In contrast, effects for cortical surface area appear global. Case-control, negative, cortical thickness effect sizes were two to three times larger in individuals receiving antipsychotic medication relative to unmedicated individuals. Negative correlations between age and bilateral temporal pole thickness were stronger in individuals with schizophrenia than in healthy volunteers. Regional cortical thickness showed significant negative correlations with normalized medication dose, symptom severity, and duration of illness and positive correlations with age at onset. CONCLUSIONS: The findings indicate that the ENIGMA meta-analysis approach can achieve robust findings in clinical neuroscience studies; also, medication effects should be taken into account in future genetic association studies of cortical thickness in schizophrenia

Staging of Schizophrenia with the Use of PANSS: An International Multi-Center Study

Introduction: A specific clinically relevant staging model for schizophrenia has not yet been developed. The aim of the current study was to evaluate the factor structure of the PANSS and develop such a staging method.Methods: Twenty-nine centers from 25 countries contributed 2358 patients aged 37.21 ± 11.87 years with schizophrenia. Analysis of covariance, Exploratory Factor Analysis, Discriminant Function Analysis, and inspection of resultant plots were performed.Results: Exploratory Factor Analysis returned 5 factors explaining 59% of the variance (positive, negative, excitement/hostility, depression/anxiety, and neurocognition). The staging model included 4 main stages with substages that were predominantly characterized by a single domain of symptoms (stage 1: positive; stages 2a and 2b: excitement/hostility; stage 3a and 3b: depression/anxiety; stage 4a and 4b: neurocognition). There were no differences between sexes. The Discriminant Function Analysis developed an algorithm that correctly classified >85% of patients.Discussion: This study elaborates a 5-factor solution and a clinical staging method for patients with schizophrenia. It is the largest study to address these issues among patients who are more likely to remain affiliated with mental health services for prolonged periods of time.<br /

Defect structure of CdZnTe

(Cd,Zn)Te single crystals fabricated in our laboratory by Vertical Gradient Freeze Method were subjected to two types of experiments. In the first experiment, samples were annealed at temperatures 600-900 °C under different Cd overpressures. They were quenched after annealing to room temperature and Hall effect and conductivity measurements were performed. In the second experiment, in situ Hall effect and conductivity measurements on neighbor samples were done also at temperatures 700-900 °C. We determined equilibrium concentrations of defects at temperatures 700-900 °C and the stoichiometry intrinsic line in the p-T diagram comparing the experiments and the theoretical model presented by Berding. Results of the presented analysis can be used to find optimal growth and annealing conditions to reduce precipitation of Cd/Te or to produce intrinsic material suitable for fabrication of (CdZn)Te gamma-ray detectors

Simulation of Electric Field in Semi Insulating Au/CdTe/Au Detector under Flux

We report our simulations on the profile of the electric field in semi insulating CdTe and CdZnTe with Au contacts under radiation flux. The type of the space charge and electric field distribution in the Au/CdTe/Au structure is at high fluxes result of a combined influence of charge formed due to band bending at the electrodes and from photo generated carriers, which are trapped at deep levels. Simultaneous solution of drift-diffusion and Poisson equations is used for the calculation. We show, that the space charge originating from trapped photo-carriers starts to dominate at fluxes 10{sup 15}-10{sup 16}cm{sup -2}s{sup -1}, when the influence of contacts starts to be negligible

Semiinsulating CdTe

Experimental conditions for the growth of near stoichiometric high-resistivity CdTe single crystals with a minimal concentration of point defects are investigated. The position of the stoichiometric line in the pressure-temperature (P-T) phase diagram is evaluated from high-temperature in situ galvanomagnetic measurements. Calculations based on a model of two major native defects (Cd vacancy and Cd interstitial) show, that a very small variation of Cd pressure P(Cd) results in a strong generation of uncompensated native defects. Modelling of room temperature carrier density dependence on the deep defect density NDD, PCd, and annealing temperature T shows, that the range of optimal PCd, at which high resistivity can be reached, broadens with increasing NDD or decreasing T. It is shown that at low T &lt;450°C the deep defect density &lt; 1015 cm-3 is sufficient to grow the high-resistivity CdTe. © 2002 Elsevier Science B.V. All rights reserved