644 research outputs found

    Rotated stripe order and its competition with superconductivity in La1.88_{1.88}Sr0.12_{0.12}CuO4_4

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    We report the observation of a bulk charge modulation in La1.88_{1.88}Sr0.12_{0.12}CuO4_4 (LSCO) with a characteristic in-plane wave-vector of (0.236, ±δ\pm \delta), with δ\delta=0.011 r.l.u. The transverse shift of the ordering wave-vector indicates the presence of rotated charge-stripe ordering, demonstrating that the charge ordering is not pinned to the Cu-O bond direction. On cooling through the superconducting transition, we find an abrupt change in the growth of the charge correlations and a suppression of the charge order parameter indicating competition between the two orderings. Orthorhombic LSCO thus helps bridge the apparent disparities between the behavior previously observed in the tetragonal "214" cuprates and the orthorhombic yttrium and bismuth-based cuprates and thus lends strong support to the idea that there is a common motif to charge order in all cuprate families.Comment: 6 pages, 4 figue

    Psychosocial correlates with depressive symptoms six years after a first episode of psychosis as compared with findings from a general population sample

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    BACKGROUND: Depression is frequently occurring during and after psychosis. The aim of this study was to analyze if the psychosocial characteristics associated with depression/depressive symptoms in the late phase of a first episode psychosis (FEP) population were different compared to persons from the general population. METHODS: A questionnaire was sent out to all individuals six years after their FEP and to a general population sample. Depressive symptoms were recorded using a self-rating scale, the Major Depression Inventory. RESULTS: Formerly FEP persons had a higher representation of depressive symptoms/depression, unemployment, financial problems and insufficient social network. Depressive symptoms/depression were found to be associated with psychosocial problems. An age and gender effect was found in the general population, but not in the FEP sample. When the psychosocial characteristics were taken into account there were no association between having had FEP and depressive symptoms. CONCLUSIONS: The association between having been a FEP patient and depressive symptoms/depression disappeared when negative social aspects were taken into account

    Reliability, validity and psychometric properties of the Greek translation of the Major Depression Inventory

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    BACKGROUND: The Major Depression Inventory (MDI) is a brief self-rating scale for the assessment of depression. It is reported to be valid because it is based on the universe of symptoms of DSM-IV and ICD-10 depression. The aim of the current preliminary study was to assess the reliability, validity and psychometric properties of the Greek translation of the MDI. METHODS: 30 depressed patients of mean age 23.41 (± 5.77) years, and 68 controls patients of mean age 25.08 (± 11.42) years, entered the study. In 18 of them, the instrument was re-applied 1–2 days later and the Translation and Back Translation made. Clinical diagnosis was reached with the use of the SCAN v.2.0 and the International Personality Disorders Examination (IPDE). The Center for Epidemiological Studies-Depression (CES-D) and the Zung Depression Rating Scale (ZDRS) were applied for cross-validation purposes. Statistical analysis included ANOVA, the Spearman Product Moment Correlation Coefficient, Principal Components Analysis and the calculation of Cronbach's α. RESULTS: Sensitivity and specificity were 0.86 and 0.94, respectively, at 26/27. Cronbach's α for the total scale was equal to 0.89. The Spearman's rho between MDI and CES-D was 0.86 and between MDI and ZDRS was 0.76. The factor analysis revealed two factors but the first accounted for 54% of variance while the second only for 9%. The test-retest reliability was excellent (Spearman's rho between 0.53 and 0.96 for individual items and 0.89 for total score). CONCLUSION: The current study provided preliminary evidence concerning the reliability and validity of the Greek translation of the MDI. Its properties are similar to those reported in the international literature, but further research is necessary

    Metal-Insulator Transition in the Two-Dimensional Hubbard Model at Half-Filling with Lifetime Effects within the Moment Approach

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    We explore the effect of the imaginary part of the self-energy, ImΣ(k,ω)Im\Sigma(\vec{k},\omega), having a single pole, Ω(k,ω)\Omega(\vec{k},\omega), with spectral weight, α(k)\alpha(\vec{k}), and quasi-particle lifetime, Γ(k)\Gamma(\vec{k}), on the density of states. We solve the set of parameters, Ω(k,ω\Omega(\vec{k},\omega), α(k)\alpha(\vec{k}), and Γ(k)\Gamma(\vec{k}) by means of the moment approach (exact sum rules) of Nolting. Our choice for Σ(k,ω)\Sigma(k,\omega), satisfies the Kramers - Kronig relationship automatically. Due to our choice of the self - energy, the system is not a Fermi liquid for any value of the interaction, a result which is also true in the moment approach of Nolting without lifetime effects. By increasing the value of the local interaction, U/WU/W, at half-filling (ρ=1/2\rho = 1/2), we go from a paramagnetic metal to a paramagnetic insulator, (Mott metal - insulator transition (MMITMMIT)) for values of U/WU/W of the order of U/W1U/W \geq 1 (WW is the band width) which is in agreement with numerical results for finite lattices and for infinity dimensions (D=D = \infty). These results settle down the main weakness of the spherical approximation of Nolting: a finite gap for any finite value of the interaction, i.e., an insulator for any finite value of U/WU/W. Lifetime effects are absolutely indispensable. Our scheme works better than the one of improving the narrowing band factor, B(k)B(\vec{k}), beyond the spherical approximation of Nolting.Comment: 5 pages and 5 ps figures (included

    Quantum and thermal ionic motion, oxygen isotope effect, and superexchange distribution in La<sub>2</sub>CuO<sub>4</sub>

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    We study the zero-point and thermal ionic motion in La2_2CuO4_4 by means of high-resolution neutron diffraction experiments. Our results demonstrate anisotropic motion of O and to a lesser extent of Cu ions, both consistent with the structure of coupled CuO6_6 octahedra, and quantify the relative effects of zero-point and thermal contributions to ionic motion. By substitution of 18^{18}O, we find that the oxygen isotope effect on the lattice dimensions is small and negative (0.01%-0.01\%), while the isotope effect on the ionic displacement parameters is significant (6-6 to 50%50\%). We use our results as input for theoretical estimates of the distribution of magnetic interaction parameters, JJ, in an effective one-band model for the cuprate plane. We find that ionic motion causes only small (1%1\%) effects on the average value J\langle J\rangle, which vary with temperature and O isotope, but results in dramatic (1010-20%20\%) fluctuations in JJ values that are subject to significant (88-12%12\%) isotope effects. We demonstrate that this motional broadening of JJ can have substantial effects on certain electronic and magnetic properties in cuprates.Comment: 13 pages, 9 figure

    Psychiatric services in primary care settings: a survey of general practitioners in Thailand

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    BACKGROUND: General Practitioners (GPs) in Thailand play an important role in treating psychiatric disorders since there is a shortage of psychiatrists in the country. Our aim was to examine GP's perception of psychiatric problems, drug treatment and service problems encountered in primary care settings. METHODS: We distributed 1,193 postal questionnaires inquiring about psychiatric practices and service problems to doctors in primary care settings throughout Thailand. RESULTS: Four hundred and thirty-four questionnaires (36.4%) were returned. Sixty-seven of the respondents (15.4%) who had taken further special training in various fields were excluded from the analysis, giving a total of 367 GPs in this study. Fifty-six per cent of respondents were males and they had worked for 4.6 years on average (median = 3 years). 65.6% (SD = 19.3) of the total patients examined had physical problems, 10.7% (SD = 7.9) had psychiatric problems and 23.9% (SD = 16.0) had both problems. The most common psychiatric diagnoses were anxiety disorders (37.5%), alcohol and drugs abuse (28.1%), and depressive disorders (29.2%). Commonly prescribed psychotropic drugs were anxiolytics and antidepressants. The psychotropic drugs most frequently prescribed were diazepam among anti-anxiety drugs, amitriptyline among antidepressant drugs, and haloperidol among antipsychotic drugs. CONCLUSION: Most drugs available through primary care were the same as what existed 3 decades ago. There should be adequate supply of new and appropriate psychotropic drugs in primary care. Case-finding instruments for common mental disorders might be helpful for GPs whose quality of practice was limited by large numbers of patients. However, the service delivery system should be modified in order to maintain successful care for a large number of psychiatric patients

    Screening of depression in adolescents through the Internet: Sensitivity and specificity of two screening questionnaires.

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    .001). The scores on both instruments were significantly increased in all subjects with a mood disorder, whether current or lifetime, except for lifetime minor depression. In the ROC analyses, high areas under the curve were found for the MDI (0.89) and CESD (0.90). The best cut-off point for the MDI was 19 (sensitivity: 90.48; specificity: 71.53), and for the CES-D it was 22 (sensitivity: 90.48; specificity: 74.31). We conclude that the MDI and CES-D are reliable and valid instruments that can be used for this screening

    Mental health literacy and attitudes in a Swedish community sample – Investigating the role of personal experience of mental health care

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    <p>Abstract</p> <p>Background</p> <p>Mental ill health is a common condition in the general population, yet only about half of those with a mental disorder have treatment contact. Personal experience may affect attitudes, which in turn influence the help-seeking process. This study investigated differences in mental health literacy and attitudes among mentally healthy persons and in persons with symptoms of mental illness with and without treatment contact.</p> <p>Method</p> <p>A postal screening questionnaire was sent to a random sample of the general population aged 20–64 in the county of Skaraborg, Sweden in order to ascertain mental health status and history of treatment contact; 3538 responded (49%). Face-to-face interviews were carried out in random sub samples of mentally healthy persons (n = 128) and in mentally ill persons with (n = 125) and without (n = 105) mental health care contact. Mental health literacy and attitudes to treatment were assessed using questions based on a vignette depicting a person with depression. Past month mental disorder was diagnosed according to the Schedule for Clinical Assessment in Neuropsychiatry (SCAN).</p> <p>Results</p> <p>Two thirds failed to recognize depression in a vignette; recognition was equally poor in mentally healthy persons and in persons with symptoms of mental illness with and without treatment contact. In response to an open-ended question concerning appropriate interventions, one third suggested counselling and only one percent proposed antidepressant treatment. Again, proportions were similar in all groups. Persons with a history of mental health contact more often suggested that a GP would provide the best form of help. When presented with a list of possible interventions, those with a history of mental health contact were more positive to medical interventions such as antidepressants, hypnotics, and inpatient psychiatric treatment. When asked about the prognosis for the condition described in the vignette, persons with treatment contact were less likely to believe in full recovery without intervention; mentally ill without treatment contact were more optimistic.</p> <p>Conclusion</p> <p>Mental health literacy, specially concerning attitudes towards interventions is associated with personal history of mental health care.</p
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