15 research outputs found

    Tilted excitation implies odd periodic resonances

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    This work was supported by the Brazilian agencies FAPESP and CNPq. MSB also acknowledges the Engineering and Physical Sciences Research Council grant Ref. EP/I032606/1. GID thanks Felipe A. C. Pereira for fruitful discussions.Peer reviewedPostprin

    Entropy analysis of high-definition transcranial electric stimulation effects on EEG dynamics

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    A foundation of medical research is time series analysis—the behavior of variables of interest with respect to time. Time series data are often analyzed using the mean, with statistical tests applied to mean differences, and has the assumption that data are stationary. Although widely practiced, this method has limitations. Here we present an alternative statistical approach with sample analysis that provides a summary statistic accounting for the non-stationary nature of time series data. This work discusses the use of entropy as a measurement of the complexity of time series, in the context of Neuroscience, due to the non-stationary characteristic of the data. To elucidate our argument, we conducted entropy analysis on a sample of electroencephalographic (EEG) data from an interventional study using non-invasive electrical brain stimulation. We demonstrated that entropy analysis could identify intervention-related change in EEG data, supporting that entropy can be a useful “summary” statistic in non-linear dynamical systems

    On the moment dynamics of stochastically delayed linear control systems

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    In this article, the dynamics and stability of a linear system with stochastic delay and additive noise are investigated. It is assumed that the delay value is sampled periodically from a stationary distribution. A semi‐discretization technique is used to time‐discretize the system and derive the mean and second‐moment dynamics. These dynamics are used to obtain the stationary moments and the corresponding necessary and sufficient stability conditions. The application of the proposed method is illustrated through the analysis of the Hayes equation with stochastic delay and additive noise. The method is also applied to the control design of a connected automated vehicle. These examples illuminate the effects of stochastic delays on the robustness of dynamical systems

    Coherent frequency combs for spectroscopy across the 3–5 ”m region

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    CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOA tunable mid-infrared frequency comb was created via difference frequency generation. Pulses between 1 and 1.5 ”m were mixed to generate light ranging from 2.6 to 5.2 ”m. Two such combs were heterodyned at 5 ”m to show their coherence and potential for spectroscopy. The properties of the comb were modeled using numerical simulation, which confirmed the observed bandwidths. © 2017, Springer-Verlag Berlin Heidelberg (outside the USA).A tunable mid-infrared frequency comb was created via difference frequency generation. Pulses between 1 and 1.5 ÎŒm were mixed to generate light ranging from 2.6 to 5.2 ÎŒm. Two such combs were heterodyned at 5 ÎŒm to show their coherence and potential for spectroscopy. The properties of the comb were modeled using numerical simulation, which confirmed the observed bandwidths.A tunable mid-infrared frequency comb was created via difference frequency generation. Pulses between 1 and 1.5 ÎŒm were mixed to generate light ranging from 2.6 to 5.2 ÎŒm. Two such combs were heterodyned at 5 ÎŒm to show their coherence and potential for spectroscopy. The properties of the comb were modeled using numerical simulation, which confirmed the observed bandwidths.123519CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSem informaçãoSem informaçãoThe authors thank Nathan Newbury and Ian Coddington of NIST for discussions, and Dan Hickstein and Kevin Cossel of NIST for useful feedback on the manuscript. We acknowledge the support of NIST (including the Greenhouse Gas and Climate Science Measurement Program), the DARPA SCOUT program, and CNPq (Brazil). This work is a contribution of the US Government and is not subject to copyright in the United States. The mentioning of company and product names is for technical communication only and does not constitute an endorsement by NIST

    Low-dose rituximab is poorly effective in patients with primary membranous nephropathy

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    Background The optimal dosing and the efficacy of rituximab for primary membranous nephropathy (PMN) has not been established. This multicentric prospective study evaluates the efficacy and safety of low-dose rituximab (RTX) therapy in patients with PMN in clinical practice. Methods Thirty-four consecutive patients with PMN and nephrotic syndrome were included and received RTX (375 mg/m 2) once (18 patients) or twice (16 patients). RTX was the first-line therapy for 19 (56%) and the second line for 15 (44%) patients. All patients were followed for 12 months after RTX and 24 for at least 18 months (mean 23.9 \ub1 18.6 months). Results At 12 months, 5 patients (14.7%) achieved complete response, 10 (29.4%) partial and 19 (55.8%) no response. Response occurred '1/46 months after RTX. At 24 months, the clinical situation was unchanged: two non-responders achieved partial response and two responders relapsed. Responders had significantly higher baseline GFR and lower anti-PLA2R antibodies compared with non-responders. Outcome was similar between one or two doses of RTX (non-responders 55.5 versus 56%, respectively) and between patients who had received previous therapy versus those receiving RTX as first-line therapy (non-responders 40 versus 68%, respectively). In the 15 patients already treated, the response to RTX was comparable to that of previous therapies. Conclusion Low-dose RTX obtains remission in <50% of PMN patients. Probably, higher doses and longer treatments are needed to induce and maintain a response. The balance between the costs and benefits should guide the selection of the patient and the optimal dosage

    Kidney transplant patients with SARS-CoV-2 infection: The Brescia Renal COVID task force experience

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    The outcome of kidney transplant patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is still unclear. Here we describe the clinical characteristics, disease outcome, and risk factors for acute respiratory distress syndrome (ARDS) and death of a cohort of 53 kidney transplant patients with coronavirus disease 2019 (COVID-19). Eight of 53 have been handled as outpatients because of mild disease, on average with immunosuppression reduction and the addition of hydroxychloroquine and azithromycin; no patients required admission, developed ARDS, or died. Because of severe symptoms, 45/53 required admission: this cohort has been managed with immunosuppression withdrawal, methylprednisolone 16 mg/d, hydroxychloroquine, and antiviral drugs. Dexamethasone and tocilizumab were considered in case of ARDS. About 33% of the patients developed acute kidney injury, 60% ARDS, and 33% died. In this group, thrombocytopenia was associated to ARDS whereas lymphopenia at the baseline, higher D-dimer, and lack of C-reactive protein reduction were associated with risk of death. In the overall population, dyspnea was associated with the risk of ARDS and age older than 60 years and dyspnea were associated with the risk of death with only a trend toward an increased risk of death for patients on tacrolimus. In conclusion, SARS-CoV-2 infection may have a variable outcome in renal transplant patients, with higher risk of ARDS and death in the ones requiring admission

    Proteinuria and blood pressure as causal components of progression to end-stage renal failure

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    Aims. To identify the prognostic factors possibly related to end-stage renal failure development. Subjects and methods. The prognostic factors affecting chronic renal failure progression were analysed in 456 patients who had participated in a formal, multicentre, prospective randomized trial aimed at verifying the role of protein restriction in slowing down or halting the progression of chronic renal failure. The 24-month follow-up foreseen by the protocol was completed by 311 patients and 69 reached an end-point. An inductive analysis on patient survival was made by using the Cox proportional hazard regression model, using a stepwise procedure in order to select only those factors which are significantly associated with survival. For each individual risk factor, a univariate descriptive analysis of survival was performed using the Kaplan-Meier technique. Results. Underlying nephropathy, baseline plasma creatinine, proteinuria, and plasma calcium were all shown to be related to end-stage renal failure onset. Hypertensive patients (mean blood pressure &gt; 107 mmHg) had a worst cumulative renal survival but the degree of proteinuria was even more important as a prognostic factor of renal death than hypertension. The cumulative renal survival of patients whose proteinuria decreased during the trial follow-up was better than those of patients without changes. However, the interaction between baseline lying mean blood pressure and proteinuria was not significant. Conclusions. Only primary renal disease and proteinuria were related to renal survival, being baseline plasma creatinine confounding factor. By blocking the possible causal role of proteinuria and hypertension, end-stage renal failure could be prevented in a significant percentage of patients
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