Search results for: S. Merola

Authors: Giovanni Merola

Abstract:

Sparse Principal Components Analysis aims to find principal components with few non-zero loadings. We derive such sparse solutions by adding a genuine sparsity requirement to the original Principal Components Analysis (PCA) objective function. This approach differs from others because it preserves PCA's original optimality: uncorrelatedness of the components and least squares approximation of the data. To identify the best subset of non-zero loadings we propose a branch-and-bound search and an iterative elimination algorithm. This last algorithm finds sparse solutions with large loadings and can be run without specifying the cardinality of the loadings and the number of components to compute in advance. We give thorough comparisons with the existing sparse PCA methods and several examples on real datasets.

Keywords: SPCA, uncorrelated components, branch-and-bound, backward elimination

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Authors: A. Schirru, A. Irimescu, S. Merola, A. d’Adamo, S. Fontanesi

Abstract:

One of the aspects that are usually neglected during the design phase of an engine is the effect of the spark plug on the flow field inside the combustion chamber. Because of the difficulties in the experimental investigation of the mutual interaction between flow alteration and early flame kernel convection effect inside the engine combustion chamber, CFD-3D simulation is usually exploited in such cases. Experimentally speaking, a particular type of engine has to be used in order to directly observe the flame propagation process. In this study, a double electrode spark plug was fitted into an optically accessible engine and a high-speed camera was used to capture the initial stages of the combustion process. Both the arc and the kernel phases were observed. Then, a morphologic analysis was carried out and the position of the center of mass of the flame, relative to the spark plug position, was calculated. The crossflow orientation was chosen for the spark plug and the kernel growth process was observed for different air-fuel ratios. It was observed that during a normal cycle the flow field between the electrodes tends to transport the arc deforming it. Because of that, the kernel growth phase takes place away from the electrodes and the flame propagates with a preferential direction dictated by the flow field.

Keywords: Combustion, Optically Accessible Engine, Spark-Ignition Engine, Sparl Orientation, Kernel Growth

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Authors: Mia Schneeweiss, Joseph Merola

Abstract:

Atopic dermatitis (AD) is a chronic inflammatory skin condition with a prevalence of 9.6 million in children under the age of 18 in the US, 3.2 million of those suffer severe AD. AD has significant effects on the quality of life and psychiatric comorbidity in affected patients. We sought to quantify the use of psychotropic medications and mental health services in children. We used longitudinal claims data form commercially insured patients in the US between 2003 and 2016 to identify children aged 18 or younger with a diagnosis of AD associated with an outpatient or inpatient encounter. A 180-day enrollment period was required before the first diagnosis of AD. Among those diagnosed, we computed the use of psychiatric services and dispensing of psychotropic medications during the following 6 months. Among 1.6 million children <18 years with a diagnosis of AD, most were infants (0-1 years: 17.6%), babies (1-2 years: 12.2%) and young children (2-4 years: 15.4). 5.1% were in age group 16-18 years. Among younger children 50% of patients were female, after the age of 14 about 60% were female. In 16-18 years olds 6.4% had at least one claim with a recorded psychopathology during the 6-month baseline period; 4.6% had depression, 3.3% anxiety, 0.3% panic disorder, 0.6% psychotic disorder, 0.1% anorexia. During the 6 months following the physician diagnosis of AD, 66% used high-potency topical corticosteroids, 3.5% used an SSRI, 0.3% used an SNRI, 1.2% used a tricyclic antidepressant, 1.4% used an antipsychotic medication, and 5.2% used an anxiolytic agent. 4.4% had an outpatient visit with a psychiatrist and 0.1% had been hospitalized with a psychiatric diagnosis. In 14-16 years olds, 4.7% had at least one claim with a recorded psychopathology during the 6-month baseline period; 3.3% had depression, 2.5% anxiety, 0.2% panic disorder, 0.5% psychotic disorder, 0.1% anorexia. During the 6 months following the physician diagnosis of AD, 68% used high-potency topical corticosteroids, 4.6% used an SSRI, 0.6% used an SNRI, 1.5% used a tricyclic antidepressant, 1.4% used an antipsychotic medication, and 4.6% used an anxiolytic agent. 4.7% had an outpatient visit with a psychiatrist and 0.1% had been hospitalized with a psychiatric diagnosis. In 12-14 years olds, 3.3% had at least one claim with a recorded psychopathology during the 6-month baseline period; 1.9% had depression, 2.2% anxiety, 0.1% panic disorder, 0.7% psychotic disorder, 0.0% anorexia. During the 6 months following the physician diagnosis of AD, 67% used high-potency topical corticosteroids, 2.1% used an SSRI, 0.1% used an SNRI, 0.7% used a tricyclic antidepressant, 0.9 % used an antipsychotic medication, and 4.1% used an anxiolytic agent. 3.8% had an outpatient visit with a psychiatrist and 0.05% had been hospitalized with a psychiatric diagnosis. In younger children psychopathologies were decreasingly common: 10-12: 2.8%; 8-10: 2.3%; 6-8: 1.3%; 4-6: 0.6%. In conclusion, there is substantial psychiatric comorbidity among children, <18 years old, with diagnosed atopic dermatitis in a US commercially insured population. Meaningful psychiatric medication use (>3%) starts as early as 12 years old.

Keywords: pediatric atopic dermatitis, phychotropic medication use, psychiatric comorbidity, claims database

Procedia PDF Downloads 152