82 research outputs found

    The bootstrap -A review

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    The bootstrap, extensively studied during the last decade, has become a powerful tool in different areas of Statistical Inference. In this work, we present the main ideas of bootstrap methodology in several contexts, citing the most relevant contributions and illustrating with examples and simulation studies some interesting aspects

    Amplitude equations close to a triple-(+1) bifurcation point of D4-symmetric periodic orbits in O(2) equivariant systems

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    A two-dimensional thermal convection problem in a circular annulus subject to a constant inward radial gravity and heated from the inside is considered. A branch of spatio-temporal symmetric periodic orbits that are known only numerically shows a multi-critical codimension-two point with a triple +1-Floquet multiplier. The weakly nonlinear analysis of the dynamics near such point is performed by deriving a system of amplitude equations using a perturbation technique, which is an extension of the Lindstedt-Poincaré method, and solvability conditions. The results obtained using the amplitude equation are compared with those from the original system of partial differential equations showing a very good agreement

    Unsteady residual distribution schemes for transition prediction

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    In this work, the unsteady simulation of the Navier–Stokes equations is carried out by using a Residual Distribution Schemes (RDS) methodology. This algorithm has a compact stencil (cell-based computations) and uses a finite element like method to compute the residual over the cell. The RDS method has been successfully proven in steady Navier–Stokes computation but its application to fully unsteady configurations is still not closed, because some of the properties of the steady counterpart can be lost. Here, we proposed a numerical solution for unsteady problems that is fully compatible with the original approach. In order to check the method, we chose a very demanding test case, namely the numerical simulation of a Tollmien–Schlichting (TS) wave in a 2D boundary layer. The evolution of this numerical perturbation is accurately computed and checked against theoretical results

    Evaluation of Clinical Factors Predictive of Diabetes Remission Following Bariatric Surgery

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    Bariatric surgery is an effective treatment for achieving significant weight loss and improving metabolic comorbidities such as type 2 diabetes mellitus (T2DM). The aim of our study was to investigate clinical factors related to T2DM remission in obese patients who had undergone bariatric surgery. Methods: A cohort of patients with T2DM and a minimum of class II obesity undergoing bariatric surgery had their clinical and anthropometric variables assessed. The statistical evaluation included multivariate analyses of clinical factors predicting a T2DM remission two years post-surgery. Results: 83 patients were included (mean age 44.13 +/- 10.38 years). Two years post-surgery, the percentage of excess weight lost was 63.43 +/- 18.59%, and T2DM was resolved in 79.5% of the patients. T2DM remission was directly related to a high body mass index (BMI) (OR: 1.886; p = 0.022) and the absence of macro-vascular complications (OR: 34.667; p = 0.002), while it was inversely associated with T2DM with a duration longer than 5 years (OR: 0.022; p = 0.040) and baseline insulin treatment (OR: 0.001; p = 0.009). 15.6% of the patients presented early complications and 20.5% developed late complications. Conclusion: In our study sample, bariatric surgery proved to be an effective and safe technique for sustained medium-term weight loss and the resolution of T2DM. A higher baseline BMI, a shorter T2DM duration, non-insulin treatment, and the absence of macro-vascular complications are factors predictive of T2DM remission

    Rationale and design of the pragmatic clinical trial tREatment with Beta-blockers after myOcardial infarction withOut reduced ejection fracTion (REBOOT).

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    There is a lack of evidence regarding the benefits of β-blocker treatment after invasively managed acute myocardial infarction (MI) without reduced left ventricular ejection fraction (LVEF). The tREatment with Beta-blockers after myOcardial infarction withOut reduced ejection fracTion (REBOOT) trial is a pragmatic, controlled, prospective, randomized, open-label blinded endpoint (PROBE design) clinical trial testing the benefits of β-blocker maintenance therapy in patients discharged after MI with or without ST-segment elevation. Patients eligible for participation are those managed invasively during index hospitalization (coronary angiography), with LVEF >40%, and no history of heart failure (HF). At discharge, patients will be randomized 1:1 to β-blocker therapy (agent and dose according to treating physician) or no β-blocker therapy. The primary endpoint is a composite of all-cause death, non-fatal reinfarction, or HF hospitalization over a median follow-up period of 2.75 years (minimum 2 years, maximum 3 years). Key secondary endpoints include the incidence of the individual components of the primary composite endpoint, the incidence of cardiac death, and incidence of malignant ventricular arrhythmias or resuscitated cardiac arrest. The primary endpoint will be analysed according to the intention-to-treat principle. The REBOOT trial will provide robust evidence to guide the prescription of β-blockers to patients discharged after MI without reduced LVEF.REBOOT is a non-commercial trial whose main sponsor is the Spanish National Center for Cardiovascular Research (CNIC). The study also received partial funding from the BI group through the CIBERCV network.S

    Anti-IL-6 Receptor Tocilizumab in Refractory Graves? Orbitopathy: National Multicenter Observational Study of 48 Patients

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    Graves’ orbitopathy (GO) is the most common extrathyroidal manifestation of Graves’ disease (GD). Our aim was to assess the e cacy and safety of Tocilizumab (TCZ) in GO refractory to conventional therapy. This was an open-label multicenter study of glucocorticoid-resistant GO treated with TCZ. The main outcomes were the best-corrected visual acuity (BVCA), Clinical Activity Score (CAS) and intraocular pressure (IOP). These outcome variables were assessed at baseline, 1st, 3rd, 6th and 12th month after TCZ therapy onset. The severity of GO was assessed according to the European Group on Graves’ Orbitopathy (EUGOGO). We studied 48 (38 women and 10 men) patients (95 eyes); mean age standard deviation 51 11.8 years. Before TCZ and besides oral glucocorticoids, they had received IV methylprednisolone (n = 43), or selenium (n = 11). GO disease was moderate (n =29) or severe (n = 19) and dysthyroid optic neuropathy (DON) (n = 7). TCZ was used in monotherapy (n = 45) or combined (n = 3) at a dose of 8 mg/kg IV every four weeks (n = 43) or 162 mg/s.c. every week (n = 5). TCZ yielded a significant improvement in all of the main outcomes at the 1st month that was maintained at one year. Comparing the baseline with data at 1 year all of the variables improved; BCVA (0.78 0.25 vs. 0.9 0.16; p = 0.0001), CAS (4.64 1.5 vs. 1.05 1.27; p = 0.0001) and intraocular pressure (IOP) (19.05 4.1 vs. 16.73 3.4 mmHg; p = 0.007). After a mean follow-up of 16.1 2.1 months, low disease activity (CAS 3), was achieved in 88 eyes (92.6%) and TCZ was withdrawn in 29 cases due to low disease activity (n = 25) or ine cacy (n = 4). No serious adverse events were observed. In conclusion, TCZ is a useful and safe therapeutic option in refractory GO treatment.This work was also partially supported by RETICS Programs, RD08/0075 (RIER) and RD12/0009/0013 from “Instituto de Salud Carlos III” (ISCIII) (Spain)

    Nuevas terapias dirigidas para el tratamiento del cáncer

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    El cáncer es el término que se utiliza para englobar un conjunto de enfermedades que se caracterizan por el crecimiento descontrolado de células alteradas molecularmente por mutaciones o modificaciones epigenéticas.En la presente revisión describimos algunas terapias dirigidas que se están utilizando actualmente en clínic
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