1,434 research outputs found

    Low autocorrelated multi-phase sequences

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    The interplay between the ground state energy of the generalized Bernasconi model to multi-phase, and the minimal value of the maximal autocorrelation function, Cmax=maxKCKC_{max}=\max_K{|C_K|}, K=1,..N1K=1,..N-1, is examined analytically and the main results are: (a) The minimal value of minNCmax\min_N{C_{max}} is 0.435N0.435\sqrt{N} significantly smaller than the typical value for random sequences O(logNN)O(\sqrt{\log{N}}\sqrt{N}). (b) minNCmax\min_N{C_{max}} over all sequences of length N is obtained in an energy which is about 30% above the ground-state energy of the generalized Bernasconi model, independent of the number of phases m. (c) The maximal merit factor FmaxF_{max} grows linearly with m. (d) For a given N, minNCmaxN/m\min_N{C_{max}}\sim\sqrt{N/m} indicating that for m=N, minNCmax=1\min_N{C_{max}}=1, i.e. a Barker code exits. The analytical results are confirmed by simulations.Comment: 4 pages, 4 figure

    Replica Field Theory for Deterministic Models (II): A Non-Random Spin Glass with Glassy Behavior

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    We introduce and study a model which admits a complex landscape without containing quenched disorder. Continuing our previous investigation we introduce a disordered model which allows us to reconstruct all the main features of the original phase diagram, including a low TT spin glass phase and a complex dynamical behavior.Comment: 35 pages with uu figures, Roma 102

    Confirmatory Factor Analysis of the French Version of the Savoring Beliefs Inventory.

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    The Savoring Beliefs Inventory (SBI) is a measure designed to assess attitudes toward savoring positive experience within three temporal orientations: the past (reminiscence), the present moment (present enjoyment), and the future (anticipation). The aim of this study was to validate the structure of the SBI-French version. The scale was tested with 335 French-speaking participants. Two models were estimated: a one-factor model representing a general construct of savoring and a three-factor model differentiating between anticipation, present enjoyment, and reminiscence. Several indicators of model fit were used: the root mean square error of approximation (RMSEA), the comparison fit index (CFI), the Tucker-Lewis fit index (TLI), and the standardized root mean residual (SRMR). A chi-square difference test was used to compare the two models. The model fit of the three-factor model assessed by the SRMR showed to be excellent, while it could be considered as satisfactory according to the CFI and TLI coefficients. RMSEA, however, was slightly less adequate. The model fit for the one-factor model seemed less adequate than the three-factor solution. Further, the chi-square difference test revealed that the three-factor model had significantly better fit than the one-factor model. Finally, the reliability of the four scores (anticipating pleasure, present moment pleasure, reminiscing pleasure, and total score) was very good. These results show that the French version of the SBI is a valid and valuable scale to measure attitudes regarding the ability to savor positive experience, whether it be in anticipation, reminiscence, or the present moment

    Development of the Positive Emotions Program for Schizophrenia (PEPS): an intervention to improve pleasure and motivation in schizophrenia

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    Objectives: The efficacy of drug-based treatments and psychological interventions on the primary negative symptoms of schizophrenia remains limited. Recent literature has distinguished negative symptoms associated with a diminished capacity to experience, from those associated with a limited capacity for expression. The positive emotions program for schizophrenia (PEPS) is a new method that specifically aims to reduce the syndrome of a diminished capacity to experience. Methods: The intervention's vital ingredients were identified through a literature review of emotion in schizophrenia and positive psychology. The program has been beta-tested on various groups of health-care professionals. Results: A detailed description of the final version of PEPS is presented here. The French version of the program is freely downloadable. Conclusion: PEPS is a specific, short, easy to use, group-based intervention to improve pleasure, and motivation in schizophrenia. It was built considering a recovery-oriented approach to schizophrenia

    Dynamical Behaviour of Low Autocorrelation Models

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    We have investigated the nature of the dynamical behaviour in low autocorrelation binary sequences. These models do have a glass transition TGT_G of a purely dynamical nature. Above the glass transition the dynamics is not fully ergodic and relaxation times diverge like a power law τ(TTG)γ\tau\sim (T-T_G)^{-\gamma} with γ\gamma close to 22. Approaching the glass transition the relaxation slows down in agreement with the first order nature of the dynamical transition. Below the glass transition the system exhibits aging phenomena like in disordered spin glasses. We propose the aging phenomena as a precise method to determine the glass transition and its first order nature.Comment: 19 pages + 14 figures, LateX, figures uuencoded at the end of the fil

    SAS: Symmetric Analysis of Z-Spectra, a Method to Evaluate B0 Correction Techniques for CEST Data in Clinical Systems Using Non-Exchanging Phantoms

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    Presentation of a method for the comparison of B0 correction methods. This method is based on non-exchanging phantoms to remove CEST effects. SAS method proposed to inform studies

    Duration of untreated psychosis: Impact of the definition of treatment onset on its predictive value over three years of treatment.

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    While reduction of DUP (Duration of Untreated Psychosis) is a key goal in early intervention strategies, the predictive value of DUP on outcome has been questioned. We planned this study in order to explore the impact of three different definition of "treatment initiation" on the predictive value of DUP on outcome in an early psychosis sample. 221 early psychosis patients aged 18-35 were followed-up prospectively over 36 months. DUP was measured using three definitions for treatment onset: Initiation of antipsychotic medication (DUP1); engagement in a specialized programme (DUP2) and combination of engagement in a specialized programme and adherence to medication (DUP3). 10% of patients never reached criteria for DUP3 and therefore were never adequately treated over the 36-month period of care. While DUP1 and DUP2 had a limited predictive value on outcome, DUP3, based on a more restrictive definition for treatment onset, was a better predictor of positive and negative symptoms, as well as functional outcome at 12, 24 and 36 months. Globally, DUP3 explained 2 to 5 times more of the variance than DUP1 and DUP2, with effect sizes falling in the medium range according to Cohen. The limited predictive value of DUP on outcome in previous studies may be linked to problems of definitions that do not take adherence to treatment into account. While they need replication, our results suggest effort to reduce DUP should continue and aim both at early detection and development of engagement strategies

    Feasibility and Accessibility of a Tailored Intervention for Informal Caregivers of People with Severe Psychiatric Disorders: a Pilot Study

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    Objectives: This study aimed to assess the acceptability and feasibility of a new tailored intervention for informal caregivers: the Ensemble (Together) program. Methods: An open pre–post within-subject comparison pilot study was conducted. Twenty-one informal caregivers completed the five-session Ensemble program. Two measurement tools were used: The Brief Symptom Inventory (BSI) and the Life Orientation Scale (LOT-R). Results: The results showed that informal caregivers were in need of individual support and were ready to participate in the Ensemble program independent of the patient’s diagnosis or stage of illness. The participants were very satisfied, and 95.4% completed the program. The preliminary results also showed that in five sessions, informal caregivers’ Global Severity Index measured by the BSI and their optimism about their future (measured by the LOT-R) were significantly improved. Conclusion: This pilot study provided preliminary results concerning the feasibility and acceptability of the tailored Ensemble program and indicates the need for a randomized trial. The Ensemble program is appropriate for both the acute and chronic phases of disease. Individualized brief and useful interventions for informal caregivers may provide more positive outcomes in care

    Impaired endothelial and smooth muscle functions and arterial stiffness appear before puberty in obese children and are associated with elevated ambulatory blood pressure

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    Aims To determine whether impaired brachial endothelial (flow-mediated dilation, FMD) and smooth muscle function (nitroglycerin-mediated dilation, NTGMD), and remodelling of the common carotid artery (CCA) develop before puberty in obese children. Methods and results Arterial intima-media thickness (IMT), FMD and NTGMD were measured by high-resolution ultrasound in 48 obese and 23 lean pre-pubertal children (8.8 ± 1.5 years old). We assessed central pulse pressure, incremental elastic modulus (Einc), casual and ambulatory systolic (SBP) and diastolic blood pressure (DBP), and body fatness by DXA. Obese children had significantly lower FMD (4.5 ± 4.0 vs. 8.3 ± 1.7%), NTGMD (19.0 ± 9.0 vs. 25.8 ± 6.1%), and increased Einc (13.9 ± 5.2 vs. 10.4 ± 5.2 mmHg/102), ambulatory SBP (121.3 ± 12.6 vs. 106.6 ± 7.1, mmHg), and DBP (69.1 ± 5.7 vs. 63.7 ± 4.5) than lean subjects, whereas IMT was not augmented. Ambulatory systolic hypertension was present in 47% of obese subjects. FMD, NTGMD, and Einc were correlated with body fatness, body mass index, and blood pressure (BP). Conclusion Impaired endothelial and smooth muscle functions and altered wall material develop before puberty in obese children, however remodelling of the CCA is not yet present. Arterial dysfunction may be considered as the first marker of atherosclerosis and is associated with elevated BP. Ambulatory blood pressure monitoring may be a potential tool to improve risk stratification in obese childre

    Persistent Correlation of Ghrelin Plasma Levels with Body Mass Index Both in Stable Weight Conditions and during Gastric-bypass-induced Weight Loss

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    Background: Studies done on serial changes in plasma ghrelin levels after gastric bypass (GBP) have yielded contrasting results since decreased, unchanged, or increased levels have been reported in the literature. This study investigates whether or not GBP has an inhibitory effect on fasting ghrelin levels independently of weight loss. Methods: Fasting ghrelin levels were measured in 115 stable body weight females, classified as normal body weight (NW; body mass index (BMI) 50kg/m2). Results: Each obese subgroup showed significantly lower ghrelin levels as compared to both NW (p < 0.0001) and OW subjects (p < 0.05 or 0.005); however, no significant differences were observed within the three obese subgroups. Forty-nine obese patients underwent a GBP. Plasma ghrelin, measured at 3, 6, and 12months after GBP, significantly increased from the sixth month on (p < 0.0001). When patients were classified, at each postoperative time point, according to their actual BMI, ghrelin was significantly (p = 0.0002) related to postoperative BMI and not significantly different from ghrelin measured in stable body weight conditions. Conclusions: Fasting ghrelin displays an inversely significant correlation with BMI in both stable body weight conditions and after GBP. No evidence was found that GBP had an effect on fasting ghrelin levels, independent of weight los
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