285 resultados para positive semi-definite matrices


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This contribution (presented in the first International Conference on Public Policy (ICPP) in Grenoble in June 2013) explores the phenomena of innovation in action ("innovative implementation"). To do so, we operationalize "innovative implementation" as a strategy by which (coalitions of) non-state actors seek to develop ad hoc solutions to address a given environmental issue, going beyond what is provided for in formal policy designs. Following an inductive research strategy, we elaborate a conceptual framework whose main advantage is to bring the actors and their coalition (in all their diversity) back in the analysis. More concretely, we state that perceiving implementation as broader 'social interaction processes' (De Boer & Bressers 2011) within which actors play strategic 'games' (Bardach 1977, Scharpf 1997) opens interesting lines of research to better account for their innovative and strategic behaviours. In a second step, we apply this framework to three strategies of innovative implementation in different contexts, and identify on this basis empirical regularities in the individual pathways related to the emergence and success (or failure) of these strategies.

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The antibiotic susceptibility and molecular epidemiology of Panton-Valentine leukocidin (PVL)-positive meticillin-resistant Staphylococcus aureus (MRSA) isolates reported from 17 countries in the Americas, Europe and, Australia-Asia were analysed. Among a total of 3236 non-duplicate isolates, the lowest susceptibility was observed to erythromycin in all regions. Susceptibility to ciprofloxacin showed large variation (25%, 75% and 84% in the Americas, Europe and Australia-Asia, respectively). Two vancomycin-intermediate PVL-positive MRSA isolates were reported, one from Hong Kong and the other from The Netherlands. Resistance to trimethoprim/sulfamethoxazole and linezolid was <1%. Among 1798 MRSA isolates from 13 countries that were tested for the requested 10 non-β-lactam antibiotics, 49.4% were multisusceptible. However, multiresistant isolates (resistant to at least three classes of non-β-lactam antibiotics) were reported from all regions. Sequence type 30 (ST30) was reported worldwide, whereas ST80 and ST93 were exclusive to Europe and Australia, respectively. USA300 and related clones (ST8) are progressively replacing the ST80 clone in several European countries. Eight major clusters were discriminated by multilocus variable-number tandem repeat assay (MLVA), showing a certain geographic specificity. PVL-positive MRSA isolates frequently remain multisusceptible to non-β-lactam agents, but multiresistance is already prevalent in all regions. Surveillance of MRSA susceptibility patterns should be monitored to provide clinicians with the most current information regarding changes in resistance patterns.

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Methicillin-resistant Staphylococcus aureus (MRSA) carrying the mecC gene (mecC-MRSA) exhibited at 37°C MICs of oxacillin close to those of methicillin-susceptible S. aureus (MSSA). We investigated whether at this temperature, mecC-MRSA strains respond to flucloxacillin treatment like MSSA strains, using a rat model of endocarditis. Flucloxacillin (human-like kinetics of 2 g intravenously every 6 h) cured 80 to 100% of aortic vegetations infected with five different mecC-MRSA strains. These results suggest that mecC-MRSA infections may successfully respond to treatment with β-lactams.

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This paper considers an alternative perspective to China's exchange rate policy. It studies a semi-open economy where the private sector has no access to international capital markets but the central bank has full access. Moreover, it assumes limited financial development generating a large demand for saving instruments by the private sector. The paper analyzes the optimal exchange rate policy by modeling the central bank as a Ramsey planner. Its main result is that in a growth acceleration episode it is optimal to have an initial real depreciation of the currency combined with an accumulation of reserves, which is consistent with the Chinese experience. This depreciation is followed by an appreciation in the long run. The paper also shows that the optimal exchange rate path is close to the one that would result in an economy with full capital mobility and no central bank intervention.

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TCF3-HLF-positive acute lymphoblastic leukemia (ALL) is currently incurable. Using an integrated approach, we uncovered distinct mutation, gene expression and drug response profiles in TCF3-HLF-positive and treatment-responsive TCF3-PBX1-positive ALL. We identified recurrent intragenic deletions of PAX5 or VPREB1 in constellation with the fusion of TCF3 and HLF. Moreover somatic mutations in the non-translocated allele of TCF3 and a reduction of PAX5 gene dosage in TCF3-HLF ALL suggest cooperation within a restricted genetic context. The enrichment for stem cell and myeloid features in the TCF3-HLF signature may reflect reprogramming by TCF3-HLF of a lymphoid-committed cell of origin toward a hybrid, drug-resistant hematopoietic state. Drug response profiling of matched patient-derived xenografts revealed a distinct profile for TCF3-HLF ALL with resistance to conventional chemotherapeutics but sensitivity to glucocorticoids, anthracyclines and agents in clinical development. Striking on-target sensitivity was achieved with the BCL2-specific inhibitor venetoclax (ABT-199). This integrated approach thus provides alternative treatment options for this deadly disease.

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The impact of round-the-clock cerebrospinal fluid (CSF) Gram stain on overnight empirical therapy for suspected central nervous system (CNS) infections was investigated. All consecutive overnight CSF Gram stains between 2006 and 2011 were included. The impact of a positive or a negative test on empirical therapy was evaluated and compared to other clinical and biological indications based on institutional guidelines. Bacterial CNS infection was documented in 51/241 suspected cases. Overnight CSF Gram stain was positive in 24/51. Upon validation, there were two false-positive and one false-negative results. The sensitivity and specificity were 41 and 99 %, respectively. All patients but one had other indications for empirical therapy than Gram stain alone. Upon obtaining the Gram result, empirical therapy was modified in 7/24, including the addition of an appropriate agent (1), addition of unnecessary agents (3) and simplification of unnecessary combination therapy (3/11). Among 74 cases with a negative CSF Gram stain and without formal indication for empirical therapy, antibiotics were withheld in only 29. Round-the-clock CSF Gram stain had a low impact on overnight empirical therapy for suspected CNS infections and was associated with several misinterpretation errors. Clinicians showed little confidence in CSF direct examination for simplifying or withholding therapy before definite microbiological results.

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BACKGROUND: Recent literature has distinguished the negative symptoms associated with a diminished capacity to experience (apathy, anhedonia) from symptoms associated with a limited capacity for expression (emotional blunting, alogia). The apathy-anhedonia syndrome tends to be associated with a poorer prognosis than the symptoms related to diminished expression. The efficacy of drug-based treatments and psychological interventions for these symptoms in schizophrenia remains limited. There is a clear clinical need for new treatments. METHODS: This pilot study tested the feasibility of a program to reduce anhedonia and apathy in schizophrenia and assessed its impact on 37 participants meeting the ICD-10 criteria for schizophrenia or schizoaffective disorders. Participants were pre- and post-tested using the Scale for the Assessment of Negative Symptoms (SANS) and the Calgary Depression Scale for Schizophrenia (CDSS). They took part in eight sessions of the Positive Emotions Program for Schizophrenia (PEPS)--an intervention that teaches participants skills to help overcome defeatist thinking and to increase the anticipation and maintenance of positive emotions. RESULTS: Thirty-one participants completed the program; those who dropped out did not differ from completers. Participation in the program was accompanied by statistically significant reductions in the total scores for Avolition-Apathy and Anhedonia-Asociality on the SANS, with moderate effect sizes. Furthermore, there was a statistically significant reduction of depression on the CDSS, with a large effect size. Emotional blunting and alogia remain stable during the intervention. DISCUSSION: Findings indicate that PEPS is both a feasible intervention and is associated with an apparently specific reduction of anhedonia and apathy. However, these findings are limited by the absence of control group and the fact that the rater was not blind to the treatment objectives. CONCLUSIONS: PEPS is a promising intervention to improve anhedonia and apathy which need to be tested further in a controlled study. TRIAL REGISTRATION NUMBER: ISRCTN registry ISRCTN74048461, registered 18 may 2015.

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BACKGROUND: Lifestyle changes and statins are the cornerstones in management of dyslipidaemia in patients with HIV infection. Replacement of an antiretroviral therapy (ART) component is a proposed therapeutic strategy to reduce cardiovascular risk. In dyslipidaemic patients with HIV infection, we assessed the efficacy of replacing boosted protease inhibitor (bPI) or efavirenz (EFV) by etravirine (ETR) as an alternative to statin therapy. MATERIALS AND METHODS: A prospective, open-label, multicentre, 12-week study of patients with HIV infection on ART including bPI or EFV, and statin treatment. Four weeks after statin interruption, bPI or EFV was switched to ETR (400 mg, 8 weeks) if serum low-density lipoprotein cholesterol (LDL-C) was ≥ 3 mM. The primary endpoint was the proportion of patients on ETR with no indication for statin treatment at study completion. Serum levels of HIV RNA, lipids and biomarkers of cardiovascular disease were also measured. (ClinicalTrials.gov: NCT01543035). RESULTS: The 31 included patients had a HIV-1 RNA < 50 copies/mL (median age, 52 years; median CD4, 709 cell/mL; median LDL-C, 2·89 mM), 68% were on EFV, and 32% were on bPI. At week 4, 27 patients switched to ETR. At study completion, 15 patients (56%) on ETR did not qualify for statin treatment. After the ETR switch, serum levels of the cardiovascular biomarkers sICAM and MCP1/CCL2 decreased by 11·2% and 18·9%, respectively, and those of CCL5/RANTES and tissue inhibitor of metalloproteinase-1 increased by 14·3% and 13·4%, respectively, indicating reduced cardiovascular risk. There were no notable treatment-related adverse events. CONCLUSIONS: Replacing bPI or EFV by ETR is a viable strategy to obviate primary prevention statin treatment.

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OBJECTIVE: To evaluate the effect of adjuvant chemotherapy (AC) on mortality after radical nephroureterectomy (RNU) for upper tract urothelial carcinoma (UTUC) with positive lymph nodes (LNs) and to identify patient subgroups that are most likely to benefit from AC. PATIENTS AND METHODS: We retrospectively analysed data of 263 patients with LN-positive UTUC, who underwent full surgical resection. In all, 107 patients (41%) received three to six cycles of AC, while 156 (59.3%) were treated with RNU alone. UTUC-related mortality was evaluated using competing-risks regression models. RESULTS: In all patients (Tall N+), administration of AC had no significant impact on UTUC-related mortality on univariable (P = 0.49) and multivariable (P = 0.11) analysis. Further stratified analyses showed that only N+ patients with pT3-4 disease benefited from AC. In this subgroup, AC reduced UTUC-related mortality by 34% (P = 0.019). The absolute difference in mortality was 10% after the first year and increased to 23% after 5 years. On multivariable analysis, administration of AC was associated with significantly reduced UTUC-related mortality (subhazard ratio 0.67, P = 0.022). Limitations of this study are the retrospective non-randomised design, selection bias, absence of a central pathological review and different AC protocols. CONCLUSIONS: AC seems to reduce mortality in patients with pT3-4 LN-positive UTUC after RNU. This subgroup of LN-positive patients could serve as target population for an AC prospective randomised trial.

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In this study, we randomly compared high doses of the tyrosine kinase inhibitor imatinib combined with reduced-intensity chemotherapy (arm A) to standard imatinib/hyperCVAD (cyclophosphamide/vincristine/doxorubicin/dexamethasone) therapy (arm B) in 268 adults (median age, 47 years) with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). The primary objective was the major molecular response (MMolR) rate after cycle 2, patients being then eligible for allogeneic stem cell transplantation (SCT) if they had a donor, or autologous SCT if in MMolR and no donor. With fewer induction deaths, the complete remission (CR) rate was higher in arm A than in arm B (98% vs 91%; P = .006), whereas the MMolR rate was similar in both arms (66% vs 64%). With a median follow-up of 4.8 years, 5-year event-free survival and overall survival (OS) rates were estimated at 37.1% and 45.6%, respectively, without difference between the arms. Allogeneic transplantation was associated with a significant benefit in relapse-free survival (hazard ratio [HR], 0.69; P = .036) and OS (HR, 0.64; P = .02), with initial white blood cell count being the only factor significantly interacting with this SCT effect. In patients achieving MMolR, outcome was similar after autologous and allogeneic transplantation. This study validates an induction regimen combining reduced-intensity chemotherapy and imatinib in Ph+ ALL adult patients and suggests that SCT in first CR is still a good option for Ph+ ALL adult patients. This trial was registered at www.clinicaltrials.gov as #NCT00327678.