A propagation-separation approach to estimate the autocorrelation in a time-series

The paper presents an approach to estimate parameters of a local stationary AR(1) time series model by maximization of a local likelihood function. The method is based on a propagation-separation procedure that leads to data dependent weights defining the local model. Using free propagation of weights under homogeneity, the method is capable of separating the time series into intervals of approximate local stationarity. Parameters in different regions will be significantly different. Therefore the method also serves as a test for a stationary AR(1) model. The performance of the method is illustrated by applications to both synthetic data and real time-series of reconstructed NAO and ENSO indices and GRIP stable isotopes

Tensor Regression with Applications in Neuroimaging Data Analysis

Classical regression methods treat covariates as a vector and estimate a corresponding vector of regression coefficients. Modern applications in medical imaging generate covariates of more complex form such as multidimensional arrays (tensors). Traditional statistical and computational methods are proving insufficient for analysis of these high-throughput data due to their ultrahigh dimensionality as well as complex structure. In this article, we propose a new family of tensor regression models that efficiently exploit the special structure of tensor covariates. Under this framework, ultrahigh dimensionality is reduced to a manageable level, resulting in efficient estimation and prediction. A fast and highly scalable estimation algorithm is proposed for maximum likelihood estimation and its associated asymptotic properties are studied. Effectiveness of the new methods is demonstrated on both synthetic and real MRI imaging data.Comment: 27 pages, 4 figure

Image analysis and statistical inference in neuroimaging with R

R is a language and environment for statistical computing and graphics. It can be considered an alternative implementation of the S language developed in the 1970s and 1980s for data analysis and graphics (Becker and Chambers, 1984; Becker et al., 1988). The R language is part of the GNU project and offers versions that compile and run on almost every major operating system currently available. We highlight several R packages built specifically for the analysis of neuroimaging data in the context of functional MRI, diffusion tensor imaging, and dynamic contrast-enhanced MRI. We review their methodology and give an overview of their capabilities for neuroimaging. In addition we summarize some of the current activities in the area of neuroimaging software development in R

Allergen immunotherapy for allergic asthma: a systematic overview of systematic reviews

Background: there is clinical uncertainty about the effectiveness and safety of allergen immunotherapy (AIT) for the treatment of allergic asthma.Objectives: to undertake a systematic overview of the effectiveness, cost-effectiveness and safety of AIT for the treatment of allergic asthma.Methods: we searched nine electronic databases from inception to October 31, 2015. Systematic reviews were independently screened by two reviewers against pre-defined eligibility criteria and critically appraised using the Critical Appraisal Skills Programme quality assessment tool for systematic reviews. Data were descriptively and thematically synthesized.Results: we identified nine eligible systematic reviews; these focused on delivery of AIT through the following routes: subcutaneous (SCIT; n = 3); sublingual (SLIT; n = 4); and both SCIT and SLIT (n = 2). This evidence found that AIT delivered by SCIT and SLIT can improve medication and symptom scores and measures of bronchial hyper-reactivity. The impact on measures of lung function or asthma control was however less clear. We found no systematic review level evidence on the cost-effectiveness of SCIT or SLIT. SLIT had a favorable safety profile when compared to SCIT, particularly in relation to the risk of systemic reactions.Conclusions: AIT has the potential to achieve reductions in symptom and medication scores, but there is no clear or consistent evidence that measures of lung function can be improved. Bearing in mind the limitations of synthesizing evidence from systematic reviews and the fact that these reviews include mainly dated studies, a systematic review of current primary studies is now needed to update this evidence base, estimate the effectiveness of AIT on asthma outcomes and to investigate the relative effectiveness, cost-effectiveness and safety of SCIT and SLIT

Correlation of histopathology and symptoms in allergic and non-allergic patients with chronic rhinosinusitis

The aim of this study was to estimate and compare some histopathologic predictors of efficacy of endoscopic sinus surgery (ESS) in allergic and non-allergic patients with chronic rhinosinusitis (CRS). Symptomatology was rated in 50 allergic and 50 non-allergic patients prior to as well as 12 and 24 months after surgery. Specimens taken during the procedure were scored for goblet cells, subepithelial thickening, mast cells and eosinophils. The correlation between histopathology and symptoms was evaluated. Goblet cells and subepithelial thickening were the best predictors in both groups of patients. These parameters are significant global outcome predictors for allergic, but not for non-allergic patients. It is concluded that certain histopathologic parameters in CRS correlate with certain symptoms. Certain histopathologic changes are predictable for persistence of some bothersome symptoms after ESS. Pathologic evaluation might give prediction of response to ESS in allergic and non-allegic patients with CRS

Complement System in Healthy Term Newborns: Reference Values in Umbilical Cord Blood

Activation of the complement system occurs in several diseases. For reliable identification of complement activation in neonates, we establish reference ranges of several components in cord blood of healthy term newborns. For this study cord blood samples were taken from 125 healthy term newborns. Concentrations of C1r, C2, C5, C7, Properdin, and factors D, H, and I were determined by single radial immunodiffusion. C3a and C5a were measured by specific EIA and complement function was measured by hemolytic assays. The results were expressed as 5th percentile, median, and 95th percentile. The following respective concentrations were found: C1r: 27, 47, 65 mg/l; C2: 12.0, 18.0, 24.0 mg/l; C5: 64, 92, 127 mg/l; C7: 32, 60, 89 mg/l; Properdin: 5.6, 9.7, 14.2 mg/l; factor D: 3.6, 5.2, 7.3 mg/l; factor H: 178, 234, 296 mg/l; and factor I: 15, 24, 32 mg/l. The functional activity of the whole complement system was 24%, 43%, 97% and for the alternative pathway 39%, 58%, 76%. The concentration of the activated split products C3a was 4, 65, 255 μg/l and of C5a, 0.11, 0.26, 1.19 μg/l. These reference values may be important for the detection of deficiencies of native complement proteins or perinatal processes leading to an activation of the complement system. </jats:p