86,593 research outputs found
Contraction Analysis of Hopfield Neural Networks with Hebbian Learning
No full textMotivated by advances in neuroscience and machine learning, this paper is concerned with the modeling and analysis of Hopfield neural networks with dynamic recurrent connections undergoing Hebbian learning. To capture the synaptic sparsity of neural circuits, we propose a low dimensional formulation for the model and then characterize its key dynamical properties. First, we give a biologically-inspired forward invariance result. Then, we give sufficient conditions for the non-Euclidean contractivity of the model. Our contraction analysis leads to stability and robustness of time-varying trajectories - for networks with both excitatory and inhibitory synapses governed by both Hebbian and anti-Hebbian rules. Our proposed contractivity test is based upon biologically meaningful quantities, e.g., neural and synaptic decay rate, maximum out-degree, and the maximum synaptic strength. Finally, we show that the model satisfies Dale's principle. The effectiveness of our results is illustrated via a numerical example
Changes in medication practices for hospitalized psychiatric patients: 2009 versus 2004
No full textBackground We tested the hypothesis that combinations and total daily doses of psychotropics for hospitalized patients diagnosed with major psychiatric disorders are rising. Methods We evaluated McLean Hospital records of 481 consecutive inpatients with DSM-IV schizophrenia, schizoaffective, or bipolar disorders in 2004 (n = 278) or 2009 (n = 203) to compare characteristics and treatments. Results In 2009, Clinical Global Impression (CGI)-severity scores were 6% lower at intake and improved 1.7 times more than in 2004, as hospitalization-length decreased by 12%. Polytherapy (>= 2 psychotropics) increased in 2009 (affective or schizoaffective disorders > schizophrenia). Total psychotropics/patient (3.1-3.2) remained stable but mood-stabilizers/patient increased markedly and antipsychotics/patient decreased somewhat in 2009. Antipsychotic-choice (2009) ranked: quetiapine, aripiprazole, risperidone, and others; mood-stabilizers ranked: lamotrigine, valproate, lithium, and others (1/4 off-label). In 2009, final total antipsychotic doses (mg/day) increased by 97%, and mood-stabilizers by 75%. Adverse-effect rates fell by half. Factors differing independently for 2009 versus 2004 ranked: (a) more CGI improvement, (b) more mood-stabilizers/patient, (c) lower admission CGI scores, and (c) higher total antipsychotic dose. Comment Combinations and doses of antipsychotic and mood-stabilizing drugs for inpatients increased markedly (2004 vs. 2009) without consistent correspondence of agents/person and doses, without apparent increase in major adverse effects, and with possibly superior clinical improvement. Copyright (C) 2010 John Wiley & Sons, Ltd
B/F/TAF forgiveness to non-adherence
No full textBackground ART forgiveness is the ability of a regimen to maintain HIV-RNA suppression despite a documented imperfect adherence. We explored forgiveness of bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF). Methods In this retrospective cohort study pharmacy drug refills were used to calculate the proportion of days covered (PDC) as a proxy of adherence. Forgiveness was defined as the possibility to achieve a selected HIV-RNA threshold by a given level of imperfect adherence. A logistic model was applied to verify the impact of baseline variables and adherence on the virologic outcomes. Results We enrolled 420 adults. From them, 787 one-year time-periods were derived for a median cohort follow-up of 873 person/years. Most of them were males (73.1%); the most frequent risk factor for HIV infection was heterosexual contacts (49.5% of cases), followed by 22.5% MSM and 22.5% intravenous drug users. The median age of enrolled persons with HIV was 51 years (IQR 45-57 years); the median duration of HIV infection was 7.9 years (IQR 4-18 years) and the median nadir of CD4 cells was 277 cells/mcL (IQR 100-513 cells/mcL). Adherence showed a median of 0.97 (IQR 0.91-1.00), consequently only 17 time-periods (2.2%) in 17 different individuals (4.0%) showed HIV-RNA blood levels above 200 copies/ml. A PDC of 0.75 was sufficient to obtain in > 90% of cases the virologic outcome for both 200 copies/ml or 50 copies/ml. An adherence value of 0.85 obtained a positive response in virtually all subjects either for a cut-off of 50 or 200 copies/ml. Conclusions Long-term success of ART needs effective, well tolerated, friendly regimens. Adherence remains a crucial determinant of long-term success, but suboptimal adherence levels are relatively common. Given this, an elevated forgiveness plays a relevant role to further improve long-term outcomes and should be considered a fundamental characteristic of any antiretroviral regimen. B/F/TAF has been proved to have all of these characteristics
Effect of inspired gas temperature on lung mechanics and gas exchange in neonates in normothermia or therapeutic hypothermia
No full textBackground: Respiratory critical care guidelines suggest heating the air/oxygen mixture but do not recommend a specific temperature target. We aimed to clarify if the inspired gas temperature influences lung mechanics and gas exchange in intubated patients treated with whole body hypothermia (WBH) or normothermia (NT). Methods: Prospective cohort study enrolling neonates ventilated for perinatal asphyxia resuscitation (no lung disease) or acute hypoxemic respiratory failure. Patients were divided between those ventilated in NT or WBH. Compliance (Cdyn), airway resistances (Raw), oxygenation index (OI), PaO2/FiO2, A-a gradient, a/A ratio, estimated alveolar dead space (VDalv), ventilatory index (VI) and CO2 production (VCO2) were registered at the study beginning (inspired gas at 37°C). Then, gas temperature was decreased (32 °C) and variables were recorded again after 1 and 3 h. Data were analysed with univariate and multivariate repeated measures-ANOVA. Results: Cdyn, Raw, OI, PaO2/FiO2, A-a gradient, a/A ratio, VDalv, VI and VCO2 are similar between WBH and NT at any timepoint (between-subjects effect); these results do not change adjusting for the presence of respiratory failure. When this is considered in multivariate ANOVA (within-subjects effect), Cdyn (p = 0.016), Raw (p = 0.034) and VDalv (p < 0.001) were worse in patients with respiratory failure than in those without lung disease. Conclusions: Decreasing the gas temperature from 37 °C to 32 °C for 3 h does not change lung mechanics and gas exchange, neither in neonates with, nor in those without respiratory failure and in those treated in NT or WBH. These findings fill a knowledge gap regarding the effect of inspired gas temperature during WBH: they may inform future respiratory critical care guidelines
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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