Minimum local distance density estimation

We present a local density estimator based on first-order statistics. To estimate the density at a point, x, the original sample is divided into subsets and the average minimum sample distance to x over all such subsets is used to define the density estimate at x. The tuning parameter is thus the number of subsets instead of the typical bandwidth of kernel or histogram-based density estimators. The proposed method is similar to nearest-neighbor density estimators but it provides smoother estimates. We derive the asymptotic distribution of this minimum sample distance statistic to study globally optimal values for the number and size of the subsets. Simulations are used to illustrate and compare the convergence properties of the estimator. The results show that the method provides good estimates of a wide variety of densities without changes of the tuning parameter, and that it offers competitive convergence performance.United States. Department of Energy. Applied Mathematical Sciences Program (Award DE-FG02-08ER2585)United States. Department of Energy. Applied Mathematical Sciences Program (Award de-sc0009297

Social factors influencing child health in Ghana

Objectives Social factors have profound effects on health. Children are especially vulnerable to social influences, particularly in their early years. Adverse social exposures in childhood can lead to chronic disorders later in life. Here, we sought to identify and evaluate the impact of social factors on child health in Ghana. As Ghana is unlikely to achieve the Millennium Development Goals’ target of reducing child mortality by two-thirds between 1990 and 2015, we deemed it necessary to identify social determinants that might have contributed to the non-realisation of this goal. Methods ScienceDirect, PubMed, MEDLINE via EBSCO and Google Scholar were searched for published articles reporting on the influence of social factors on child health in Ghana. After screening the 98 articles identified, 34 of them that met our inclusion criteria were selected for qualitative review. Results Major social factors influencing child health in the country include maternal education, rural-urban disparities (place of residence), family income (wealth/poverty) and high dependency (multiparousity). These factors are associated with child mortality, nutritional status of children, completion of immunisation programmes, health-seeking behaviour and hygiene practices. Conclusions Several social factors influence child health outcomes in Ghana. Developing more effective responses to these social determinants would require sustainable efforts from all stakeholders including the Government, healthcare providers and families. We recommend the development of interventions that would support families through direct social support initiatives aimed at alleviating poverty and inequality, and indirect approaches targeted at eliminating the dependence of poor health outcomes on social factors. Importantly, the expansion of quality free education interventions to improve would-be-mother’s health knowledge is emphasised

Model adaptivity for goal-oriented inference using adjoints

An inverse problem seeks to infer unknown model parameters using observed data. We consider a goal-oriented inverse problem, where the goal of inferring parameters is to use them in predicting a quantity of interest (QoI). Recognizing that multiple models of varying fidelity and computational cost may be available to describe the physical system, we formulate a goal-oriented model adaptivity approach that leverages multiple models while controlling the error in the QoI prediction. In particular, we adaptively form a mixed-fidelity model by using models of different levels of fidelity in different subregions of the domain. Taking the solution of the inverse problem with the highest-fidelity model as our reference QoI prediction, we derive an adjoint-based third-order estimate for the QoI error from using a lower-fidelity model. Localization of this error then guides the formation of mixed-fidelity models. We demonstrate the method for example problems described by convection–diffusion–reaction models. For these examples, our mixed-fidelity models use the high-fidelity model over only a small portion of the domain, but result in QoI estimates with small relative errors. We also demonstrate that the mixed-fidelity inverse problems can be cheaper to solve and less sensitive to the initial guess than the high-fidelity inverse problems. Keyword: Inference; Goal-oriented adaptive modeling; A posteriori error estimation; Multi-fidelity modeling; AdjointsUnited States. Department of Energy ( DE-FC02-13ER26129/DE-21 SC000929

Enamel demineralization with resin modified gic and conventional composite resin - a comparative in vivo study

Background & Objectives: Fluoride releasing bonding agents can help the orthodontist to minimize enamel demineralization independent of patient cooperation. This in vivo study was conducted to evaluate the efficacy of resin modified glass ionomer cement (RMGIC) on reducing enamel demineralization around orthodontic brackets and confirm the superior caries-preventive effect of RMGIC by assessing the mutans streptococci (S. mutans) in plaque samples in vitro. Methods: 60 subjects (aged 14-20 years) scheduled to have premolar extractions as part of the orthodontic treatment plan were selected and randomly divided into 2 groups of 30 each (group 1: the brackets were bonded on the teeth using light cure composite resin and group 2: the brackets were bonded using RMGIC). Plaque scores (modification of plaque index by Silness and Loe) were recorded and plaque samples were collected before bonding, one week and one month after bonding. S.mutans colonies were recorded from the plaque samples inoculated on MSB agar plates, incubated under 95% N2 and 5% CO2 for 48 hours at 370C in a CO2 jar. After 1 month, the right maxillary and mandibular first premolars were debonded, extracted and depth of enamel demineralization area was estimated using polarized light microscope. Results: After statistical analysis, a significantly higher mean depth of demineralized lesions was noticed in group 1 as compared to group 2. A significant difference between occlusal and gingival depth was seen only in group 2, thus illustrating a wedge effect. In group 1, a statistically significant increase in the mean colony forming units (CFU) of S.mutans has been noticed at different time intervals whereas in group2, a significant increase was observed only at 1month. Unlike at 1 month, a statistically significant difference in mean CFU between group 1 and group 2 has been observed at 1 week (P<0.05). Conclusions: Enamel lesions adjacent to the bracket base on teeth bonded with the RMGIC were smaller than those on teeth bonded with a composite resin. The high “burst effect” of fluoride release for the first few days of RMGIC after bonding is confirmed by statistically significant reduction in CFU counts of S. mutans in plaque

Adjoint-consistent formulations of slip models for coupled electroosmotic flow systems

Background: Models based on the Helmholtz 'slip' approximation are often used for the simulation of electroosmotic flows. The objectives of this paper are to construct adjoint-consistent formulations of such models, and to develop adjoint-based numerical tools for adaptive mesh refinement and parameter sensitivity analysis. Methods: We show that the direct formulation of the 'slip' model is adjoint inconsistent, and leads to an ill-posed adjoint problem. We propose a modified formulation of the coupled 'slip' model, which is shown to be well-posed, and therefore automatically adjoint-consistent. Results: Numerical examples are presented to illustrate the computation and use of the adjoint solution in two-dimensional microfluidics problems. Conclusions: An adjoint-consistent formulation for Helmholtz 'slip' models of electroosmotic flows has been proposed. This formulation provides adjoint solutions that can be reliably used for mesh refinement and sensitivity analysis.University of Texas at Austin (University Continuing Fellowship

A study of acute muscle dysfunction with particular reference to dengue myopathy

Background: Acute myopathy is a common cause of acute motor quadriparesis which has various etiologies with different courses of illness and prognosis depending on the cause. Understanding this diversity helps us in proper approach toward diagnosis, predicting the prognosis, and possible complications and in improving the treatments that are being provided. This study was planned to study the clinical, electrophysiological, and etiological profile of patients presenting with acute myopathy. We also studied how dengue-related acute myopathy differs from other causes and also difference between myopathy due to myositis and hypokalemia in cases of dengue. Materials and Methods: This was a prospective, observational study involving all clinically suspected cases of acute myopathy of not more than 4 weeks duration with raised serum creatine kinase (CK) level. They were subjected to detailed clinical evaluation along with hematological, biochemical, microbiological, and electrophysiological studies and followed-up for outcome at 1 and 3 months. Muscle biopsy and histopathological examination were done in selected patients after taking informed consent. Statistical analysis was performed by appropriate methods using SPSS version 16.0 (Chicago, IL, USA). Results: We evaluated thirty patients of acute myopathy with raised CK level. Seventeen patients had fever, 11 had myalgia, and 5 had skin lesions. All presented with symmetric weakness, 17 (56.7%) patients having predominantly proximal weakness, neck or truncal weakness in 6 (20%), hyporeflexia in 12 (40%), with mean Medical Research Council (MRC) sum score of 46.67 ± 6.0. Eight (mean modified Barthel index [MBI] at presentation - 15 ± 3.7) patients had poor functional status according to MBI and 15 according to modified Rankin scale (MRS) (mean MRS score - 2.5 ± 1.2). Etiology was dengue viral infection in 14 patients; hypokalemia due to various causes other than dengue in 8; pyomyositis in 3; dermatomyositis, polymyositis, thyrotoxicosis, systemic lupus erythematosus, and unknown etiology in one each. Only eight patients had abnormal electrophysiology and seven among nine biopsies done were abnormal. At 1 month, 24 (80.0%) and 23 (76.7%) patients had achieved normal MBI and MRS scores with 28 (93.3) and 27 (90%) patients, respectively, at 3 months. Dengue with hypokalemia had less myalgia, more of hyporeflexia, and lower serum CK compared to those without hypokalemia. Conclusion: Dengue infection and hypokalemia due to various causes are the most common causes of acute myopathy and are associated with rapid and complete recovery within 1 month. Shorter duration of illness, higher MRC sum score, better disability status at presentation, lower serum CK correlate with better outcome. Biopsy was decisive in <20% cases; hence, it is not primary investigation in acute myopathy