993 resultados para 786
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v.19-20=no.693-786 (1803-1804)
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[s.c.]
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Magdeburg, Univ., Fak. für Humanwiss., Diss., 2015
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Based on Lucas functions, an improved version of the Diffie-Hellman distribution key scheme and to the ElGamal public key cryptosystem scheme are proposed, together with an implementation and computational cost. The security relies on the difficulty of factoring an RSA integer and on the difficulty of computing the discrete logarithm.
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PURPOSE: To introduce a new k-space traversal strategy for segmented three-dimensional echo planar imaging (3D EPI) that encodes two partitions per radiofrequency excitation, effectively reducing the number excitations used to acquire a 3D EPI dataset by half. METHODS: The strategy was evaluated in the context of functional MRI applications for: image quality compared with segmented 3D EPI, temporal signal-to-noise ratio (tSNR) (the ability to detect resting state networks compared with multislice two-dimensional (2D) EPI and segmented 3D EPI, and temporal resolution (the ability to separate cardiac- and respiration-related fluctuations from the desired blood oxygen level-dependent signal of interest). RESULTS: Whole brain images with a nominal voxel size of 2 mm isotropic could be acquired with a temporal resolution under half a second using traditional parallel imaging acceleration up to 4× in the partition-encode direction and using novel data acquisition speed-up of 2× with a 32-channel coil. With 8× data acquisition speed-up in the partition-encode direction, 3D reduced excitations (RE)-EPI produced acceptable image quality without introduction of noticeable additional artifacts. Due to increased tSNR and better characterization of physiological fluctuations, the new strategy allowed detection of more resting state networks compared with multislice 2D-EPI and segmented 3D EPI. CONCLUSION: 3D RE-EPI resulted in significant increases in temporal resolution for whole brain acquisitions and in improved physiological noise characterization compared with 2D-EPI and segmented 3D EPI. Magn Reson Med 72:786-792, 2014. © 2013 Wiley Periodicals, Inc.
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It has been recently emphasized that, if individuals have heterogeneous dynamics, estimates of shock persistence based on aggregate data are significatively higher than those derived from its disaggregate counterpart. However, a careful examination of the implications of this statement on the various tools routinely employed to measure persistence is missing in the literature. This paper formally examines this issue. We consider a disaggregate linear model with heterogeneous dynamics and compare the values of several measures of persistence across aggregation levels. Interestingly, we show that the average persistence of aggregate shocks, as measured by the impulse response function (IRF) of the aggregate model or by the average of the individual IRFs, is identical on all horizons. This result remains true even in situations where the units are (short-memory) stationary but the aggregate process is long-memory or even nonstationary. In contrast, other popular persistence measures, such as the sum of the autoregressive coefficients or the largest autoregressive root, tend to be higher the higher the aggregation level. We argue, however, that this should be seen more as an undesirable property of these measures than as evidence of different average persistence across aggregation levels. The results are illustrated in an application using U.S. inflation data.
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OBJECTIVES: To assess the prevalence and correlates of childhood and adolescent sexual and/or physical abuse (SPA) in bipolar I disorder (BDI) patients treated for a first episode of psychotic mania. METHODS: The Early Psychosis Prevention and Intervention Centre admitted 786 first-episode psychosis patients between 1998 and 2000. Data were collected from patients' files using a standardized questionnaire. A total of 704 files were available; 43 were excluded because of a nonpsychotic diagnosis at endpoint and 3 due to missing data regarding past stressful events. Among 658 patients with available data, 118 received a final diagnosis of BDI and were entered in this study. RESULTS: A total of 80% of patients had been exposed to stressful life events during childhood and adolescence and 24.9% to SPA; in particular, 29.8% of female patients had been exposed to sexual abuse. Patients who were exposed to SPA had poorer premorbid functioning, higher rates of forensic history, were less likely to live with family during treatment period, and were more likely to disengage from treatment. CONCLUSIONS: SPA is highly prevalent in BDI patients presenting with a first episode of psychotic mania; exposed patients have lower premorbid functional levels and poorer engagement with treatment. The context in which such traumas occur must be explored in order to determine whether early intervention strategies may contribute to diminish their prevalence. Specific psychological interventions must also be developed.
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SUMMARY: In a randomly selected cohort of Swiss community-dwelling elderly women prospectively followed up for 2.8 +/- 0.6 years, clinical fractures were assessed twice yearly. Bone mineral density (BMD) measured at tibial diaphysis (T-DIA) and tibial epiphysis (T-EPI) using dual-energy X-ray absorptiometry (DXA) was shown to be a valid alternative to lumbar spine or hip BMD in predicting fractures. INTRODUCTION: A study was carried out to determine whether BMD measurement at the distal tibia sites of T-EPI and T-DIA is predictive of clinical fracture risk. METHODS: In a predefined representative cohort of Swiss community-dwelling elderly women aged 70-80 years included in the prospective, multi-centre Swiss Evaluation of the Methods of Measurement of Osteoporotic Fracture risk (SEMOF) study, fracture risk profile was assessed and BMD measured at the lumbar spine (LS), hip (HIP) and tibia (T-DIA and T-EPI) using DXA. Thereafter, clinical fractures were reported in a bi-yearly questionnaire. RESULTS: During 1,786 women-years of follow-up, 68 clinical fragility fractures occurred in 61 women. Older age and previous fracture were identified as risk factors for the present fractures. A decrease of 1 standard deviation in BMD values yielded a 1.5-fold (HIP) to 1.8-fold (T-EPI) significant increase in clinical fragility fracture hazard ratio (adjusted for age and previous fracture). All measured sites had comparable performance for fracture prediction (area under the curve range from 0.63 [LS] to 0.68 [T-EPI]). CONCLUSION: Fracture risk prediction with BMD measurements at T-DIA and T-EPI is a valid alternative to BMD measurements at LS or HIP for patients in whom these sites cannot be accessed for clinical, technical or practical reasons.
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OBJECTIVES: Previous literature suggests that early psychosis (EP) patients with a history of offending behavior (HOB) have specific clinical needs. The aims of this study were to assess: (1) the prevalence of HOB in a representative sample of EP; (2) the premorbid and baseline characteristics of patients with HOB, and (3) the potential differences in short-term outcome of such patients when compared to patients without HOB. METHODS: The Early Psychosis Prevention and Intervention Centre (EPPIC) admitted 786 EP patients between 1998 and 2000. Data were collected from patients' files using a standardized questionnaire. Data of 647 patients could be analyzed. RESULTS: HOB patients (29% of the sample) were more likely to be male with lower level of premorbid functioning and education, have used illicit substances and have attempted suicide. They presented with a more complex clinical picture and had poorer 18-month outcome. Most importantly, they had a significantly longer duration of untreated psychosis. CONCLUSIONS: On the basis of the high prevalence and specific features of EP patients with HOB, our study confirms a need for additional research in this domain and for the development of specific treatment strategies. Most importantly, it suggests a need for the promotion of early detection strategies among the populations of young offenders, considering that some of them may be going through the early phases of a psychotic disorder and that reduction of treatment delay and provision of well adapted interventions may have a significant impact at numerous levels in such patients.
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The formation and accumulation of toxic amyloid-β peptides (Aβ) in the brain may drive the pathogenesis of Alzheimer's disease. Accordingly, disease-modifying therapies for Alzheimer's disease and related disorders could result from treatments regulating Aβ homeostasis. Examples are the inhibition of production, misfolding, and accumulation of Aβ or the enhancement of its clearance. Here we show that oral treatment with ACI-91 (Pirenzepine) dose-dependently reduced brain Aβ burden in AβPPPS1, hAβPPSL, and AβPP/PS1 transgenic mice. A possible mechanism of action of ACI-91 may occur through selective inhibition of muscarinic acetylcholine receptors (AChR) on endothelial cells of brain microvessels and enhanced Aβ peptide clearance across the blood-brain barrier. One month treatment with ACI-91 increased the clearance of intrathecally-injected Aβ in plaque-bearing mice. ACI-91 also accelerated the clearance of brain-injected Aβ in blood and peripheral tissues by favoring its urinal excretion. A single oral dose of ACI-91 reduced the half-life of interstitial Aβ peptide in pre-plaque mhAβPP/PS1d mice. By extending our studies to an in vitro model, we showed that muscarinic AChR inhibition by ACI-91 and Darifenacin augmented the capacity of differentiated endothelial monolayers for active transport of Aβ peptide. Finally, ACI-91 was found to consistently affect, in vitro and in vivo, the expression of endothelial cell genes involved in Aβ transport across the Blood Brain Brain (BBB). Thus increased Aβ clearance through the BBB may contribute to reduced Aβ burden and associated phenotypes. Inhibition of muscarinic AChR restricted to the periphery may present a therapeutic advantage as it avoids adverse central cholinergic effects.
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L'objectiu d'aquest treball és fer el disseny i la implementació d'un sistema de control de projectes per a una organització X, de manera que la seva estructura i funcionament compleixin uns requisits inicials.
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To evaluate the long-term impact of successive interventions on rates of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection and MRSA bacteremia in an endemic hospital-wide situation. DESIGN:Quasi-experimental, interrupted time-series analysis. The impact of the interventions was analyzed by use of segmented regression. Representative MRSA isolates were typed by use of pulsed-field gel electrophoresis. SETTING:A 950-bed teaching hospital in Seville, Spain. PATIENTS:All patients admitted to the hospital during the period from 1995 through 2008. METHODS:Three successive interventions were studied: (1) contact precautions, with no active surveillance for MRSA; (2) targeted active surveillance for MRSA in patients and healthcare workers in specific wards, prioritized according to clinical epidemiology data; and (3) targeted active surveillance for MRSA in patients admitted from other medical centers. RESULTS:Neither the preintervention rate of MRSA colonization or infection (0.56 cases per 1,000 patient-days [95% confidence interval {CI}, 0.49-0.62 cases per 1,000 patient-days]) nor the slope for the rate of MRSA colonization or infection changed significantly after the first intervention. The rate decreased significantly to 0.28 cases per 1,000 patient-days (95% CI, 0.17-0.40 cases per 1,000 patient-days) after the second intervention and to 0.07 cases per 1,000 patient-days (95% CI, 0.06-0.08 cases per 1,000 patient-days) after the third intervention, and the rate remained at a similar level for 8 years. The MRSA bacteremia rate decreased by 80%, whereas the rate of bacteremia due to methicillin-susceptible S. aureus did not change. Eighty-three percent of the MRSA isolates identified were clonally related. All MRSA isolates obtained from healthcare workers were clonally related to those recovered from patients who were in their care. CONCLUSION:Our data indicate that long-term control of endemic MRSA is feasible in tertiary care centers. The use of targeted active surveillance for MRSA in patients and healthcare workers in specific wards (identified by means of analysis of clinical epidemiology data) and the use of decolonization were key to the success of the program.
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We evaluated whether preeclampsia is associated with elevated circulating levels of High mobility group box 1 protein (HMGB-1), a nuclear protein with proinflammatory effects when released extracellularly. We enrolled 48 women, 32 in third trimester pregnancy (16 with, 16 without preeclampsia), and 16 healthy non pregnant. In the peripheral blood of pregnant women, HMGB-1 concentration was assessed serially, before and after delivery. With or without preeclampsia, third trimester pregnancy was associated with elevated levels of HMGB-1. This elevation is exaggerated in preeclampsia. The source of HMGB-1 observed in these conditions is likely to involve tissues other than the placenta itself.
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OBJECTIVES: To assess the prevalence and predictors of service disengagement in a treated epidemiological cohort of first-episode psychosis (FEP) patients. METHODS: The Early Psychosis Prevention and Intervention Centre (EPPIC) in Australia admitted 786 FEP patients from January 1998 to December 2000. Treatment at EPPIC is scheduled for 18 months. Data were collected from patients' files using a standardized questionnaire. Seven hundred four files were available; 44 were excluded, because of a non-psychotic diagnosis at endpoint (n=43) or missing data on service disengagement (n=1). Rate of service disengagement was the outcome of interest, as well as pre-treatment, baseline, and treatment predictors of service disengagement, which were examined via Cox proportional hazards models. RESULTS: 154 patients (23.3%) disengaged from service. A past forensic history (Hazard ratio [HR]=1.69; 95%CI 1.17-2.45), lower severity of illness at baseline (HR=0.59; 95%CI 0.48-0.72), living without family at discharge (HR=1.75; 95%CI 1.22-2.50) and persistence of substance use disorder during treatment (HR=2.30; 95%CI 1.45-3.66) were significant predictors of disengagement from service. CONCLUSIONS: While engagement strategies are a core element in the treatment of first-episode psychosis, particular attention should be paid to these factors associated with disengagement. Involvement of the family in the treatment process, and focusing on reduction of substance use, need to be pursued in early intervention services.