Multiple sparse representations classification

Sparse representations classification (SRC) is a powerful technique for pixelwise classification of images and it is increasingly being used for a wide variety of image analysis tasks. The method uses sparse representation and learned redundant dictionaries to classify image pixels. In this empirical study we propose to further leverage the redundancy of the learned dictionaries to achieve a more accurate classifier. In conventional SRC, each image pixel is associated with a small patch surrounding it. Using these patches, a dictionary is trained for each class in a supervised fashion. Commonly, redundant/overcomplete dictionaries are trained and image patches are sparsely represented by a linear combination of only a few of the dictionary elements. Given a set of trained dictionaries, a new patch is sparse coded using each of them, and subsequently assigned to the class whose dictionary yields the minimum residual energy.We propose a generalization of this scheme. The method, which we call multiple sparse representations classification (mSRC), is based on the observation that an overcomplete, class specific dictionary is capable of generating multiple accurate and independent estimates of a patch belonging to the class. So instead of finding a single sparse representation of a patch for each dictionary, we find multiple, and the corresponding residual energies provides an enhanced statistic which is used to improve classification. We demonstrate the efficacy of mSRC for three example applications: pixelwise classification of texture images, lumen segmentation in carotid artery magnetic resonance imaging (MRI), and bifurcation point detection in carotid artery MRI. We compare our method with conventional SRC, K-nearest neighbor, and support vector machine classifiers. The results show that mSRC outperforms SRC and the other reference methods. In addition, we present an extensive evaluation of the effect of the main mSRC parameters: patch size, dictionary size, and sparsity level

Meditation and yoga practice are associated with smaller right amygdala volume: the Rotterdam study

To determine the association between meditation and yoga practice, experienced stress, and amygdala and hippocampal volume in a large population-based study. This study was embedded within the population-based Rotterdam Study and included 3742 participants for cross-sectional association. Participants filled out a questionnaire assessing meditation practice, yoga practice, and experienced stress, and underwent a magnetic resonance scan of the brain. 2397 participants underwent multiple brain scans, and were assessed for structural change over time. Amygdala and hippocampal volumes were regions of interest, as these are structures that may be affected by meditation. Multivariable linear regression analysis and mixed linear models were performed adjusted for age, sex, educational level, intracranial volume, cardiovascular risk, anxiety, depression and stress. 15.7% of individuals participated in at least one form of practice. Those who performed meditation and yoga

Early discontinuation of empirical antibiotic treatment in neutropenic patients with acute myeloid leukaemia and high-risk myelodysplastic syndrome

Introduction: Current guidelines advocate empirical antibiotic treatment (EAT) in haematological patients with febrile neutropenia. However, the optimal duration of EAT is unknown. In 2011, we have introduced a protocol, promoting discontinuation of carbapenems as EAT after 3 days in most patients and discouraging the standard use of vancomycin. This study assesses the effect of introducing this protocol on carbapenem and vancomycin use in high-risk haematological patients and its safety. Methods: A retrospective before-after study was performed comparing a cohort from 2007 to 2011 (period I, before restrictive EAT use) with a cohort from 2011 to 2014 (period II, restrictive EAT use). Neutropenic episodes related to chemotherapy or stem cell transplantation (SCT) in patients with acute myeloid leukaemia (AML) or high-risk myelodysplastic syndrome (MDS) were analysed. The primary outcome was the use of carbapenems and vancomycin as EAT during neutropenia, expressed as days of therapy (DOT)/100 neutropenic days and analysed with interrupted time series (ITS). Also the use of other antibiotics was analysed. Safety measurements included 30-day mortality, ICU admittance within 30 days after start of EAT and positive blood cultures with carbapenem-susceptible microorganisms. Results: Three hundred sixty-two neutropenic episodes with a median duration of 18 days were analysed, involving 201 patients. ITS analysis showed decreased carbapenem use with a step change of - 16.1 DOT/100 neutropenic days (95% CI - 26.77 to - 1.39) and an overall reduction of 21.6% (8.7 DOT/100 neutropenic days). Vancomycin use decreased with a step change of - 13.7 DOT/100 neutropenic days (95% CI - 23.75 to - 3.0) and an overall reduction of 54.7% (14.6 DOT/100 neutropenic days). The use of all antibiotics combined decreased from 155.6 to 138 DOT/100 neutropenic days, a reduction of 11.3%. No deaths directly related to early discontinuation of EAT were identified, also no notable difference in ICU-admission (9/116 in period I, 9/152 in period II) and positive blood cultures (4/116 in period I, 2/152 in period II) was detected. Conclusion: The introduction of a protocol promoting restrictive use of EAT resulted in reduction of carbapenem and vancomycin use and appears to be safe in AML or high-risk MDS patients with febrile neutropenia during chemotherapy or SCT

Differential patterns of age-related cortical and subcortical functional connectivity in 6-to-10 year old children: A connectome-wide association study

Introduction: Typical brain development is characterized by specific patterns of maturation of functional networks. Cortico-cortical connectivity generally increases, whereas subcortico-cortical connections often decrease. Little is known about connectivity changes amongst different subcortical regions in typical development. Methods: This study examined age- and gender-related differences in functional connectivity between and within cortical and subcortical regions using two different approaches. The participants included 411 six- to ten-year-old typically developing children sampled from the population-based Generation R study. Functional connectomes were defined in native space using regions of interest from subject-specific FreeSurfer segmentations. Connections were defined as: (a) the correlation between regional mean time-series; and (b) the focal maximum of voxel-wise correlations within FreeSurfer regions. The association of age and gender with each functional connection was determined using linear regression. The preprocessing included the exclusion of children with excessive head motion and scrubbing to reduce the influence of minor head motion during scanning. Results: Cortico-cortical associations echoed previous findings that connectivity shifts from short to long-range with age. Subcortico-cortical associations with age were primarily negative in the focal network approach but were both positive and negative in the mean time-series network approach. Between subcortical regions, age-related associations were negative in both network approaches. Few connections had significant associations with gender. Conclusions: The present study replicates previously reported age-related patterns of connectivity in a relatively narrow age-range of children. In addition, we extended these findings by demonstrating decreased connectivity within the subcortex with increasing age. Lastly, we show the utility of a more focal approach that challenges the spatial assumptions made by the traditional mean time series approach

Elevated monocyte-specific type I interferon signalling correlates positively with cardiac healing in myocardial infarct patients but interferon alpha application deteriorates myocardial healing in rats

Contains fulltext : 198360.pdf (publisher's version ) (Open Access

Mitochondrial complex I dysfunction and altered NAD(P)H kinetics in rat myocardium in cardiac right ventricular hypertrophy and failure

AIMS: In cardiac hypertrophy (CH) and heart failure (HF), alterations occur in mitochondrial enzyme content and activities but the origin and implications of these changes for mitochondrial function need to be resolved. METHODS AND RESULTS: Right ventricular CH or HF was induced by monocrotaline injection, which causes pulmonary artery hypertension, in rats. Results were compared with saline injection (CON). NAD(P)H and FAD autofluorescence were recorded in thin intact cardiac trabeculae during transitions in stimulation frequency, to assess mitochondrial complex I and complex II function, respectively. Oxygen consumption, mitochondrial morphology, protein content, and enzymatic activity were assessed. NAD(P)H autofluorescence upon an increase in stimulation frequency showed a rapid decline followed by a slow recovery. FAD autofluorescence followed a similar time course, but in opposite direction. The amplitude of the early rapid change in NAD(P)H autofluorescence was severely depressed in CH and HF compared with CON. The rapid changes in FAD autofluorescence in CH and HF were reduced to a lesser extent. Complex I-coupled respiration showed an approximately 3.5-fold reduction in CH and HF; complex II-coupled respiration was depressed two-fold in HF. Western blot analyses revealed modest reductions in complex I protein content in CH and HF and in complex I activity in supercomplexes in HF. Mitochondrial volume density was similar, but mitochondrial remodelling was evident from changes in ultrastructure and fusion/fission indices in CH and HF. CONCLUSION: These results suggest that the alterations in mitochondrial function observed in right ventricular CH and HF can be mainly attributed to complex I dysfunction