A RECOMMENDER MODEL USING SOCIAL TIE STRENGTH FOR THE CHUNK LEARNING SYSTEM

With the onset of COVID-19, rising tuition costs, and technological advancements, online courses have become a pervasive medium through which education is conducted. Currently, several online educational services tailor education to students through various methods of recommender models. One such system, the Curated Heuristic Using a Network of Knowledge (CHUNK) Learning, developed at the Naval Postgraduate School, uses a recommender system that relies on user profile attributes. We propose a complementary recommendation system to expand upon CHUNK's current recommender method by incorporating implicit recommendations from a user's social network based on tie strength between learners. In this work, we create a synthetic social network of learners and calculate the Jaccard Index and Pearson Correlation Coefficient similarity values to distinguish between strong and weak social ties. These tie classifications are then used to personalize content recommendations and expose users to greater breadth or depth of applicable knowledge based on current interests or job goals. We simulate recommendations for a user under different circumstances and show that our recommender system promotes the algorithmic formation of communities of learners on similar educational tracks. This promotes the social-emotional support for online learners that they may not currently receive and improves socialization within distance learning.Ensign, United States NavyApproved for public release. Distribution is unlimited

The Alternate Arm Converter: A New Hybrid Multilevel Converter With DC-Fault Blocking Capability

This paper explains the working principles, supported by simulation results, of a new converter topology intended for HVDC applications, called the alternate arm converter (AAC). It is a hybrid between the modular multilevel converter, because of the presence of H-bridge cells, and the two-level converter, in the form of director switches in each arm. This converter is able to generate a multilevel ac voltage and since its stacks of cells consist of H-bridge cells instead of half-bridge cells, they are able to generate higher ac voltage than the dc terminal voltage. This allows the AAC to operate at an optimal point, called the “sweet spot,” where the ac and dc energy flows equal. The director switches in the AAC are responsible for alternating the conduction period of each arm, leading to a significant reduction in the number of cells in the stacks. Furthermore, the AAC can keep control of the current in the phase reactor even in case of a dc-side fault and support the ac grid, through a STATCOM mode. Simulation results and loss calculations are presented in this paper in order to support the claimed features of the AAC

Orthogonalization of vectors with minimal adjustment

Two transformations are proposed that give orthogonal components with a one-to-one correspondence between the original vectors and the components. The aim is that each component should be close to the vector with which it is paired, orthogonality imposing a constraint. The transformations lead to a variety of new statistical methods, including a unified approach to the identification and diagnosis of collinearities, a method of setting prior weights for Bayesian model averaging, and a means of calculating an upper bound for a multivariate Chebychev inequality. One transformation has the property that duplicating a vector has no effect on the orthogonal components that correspond to nonduplicated vectors, and is determined using a new algorithm that also provides the decomposition of a positive-definite matrix in terms of a diagonal matrix and a correlation matrix. The algorithm is shown to converge to a global optimum

Use of evidence to support healthy public policy: a policy effectiveness-feasibility loop

Public policy plays a key role in improving population health and in the control of diseases, including non-communicable diseases. However, an evidence-based approach to formulating healthy public policy has been difficult to implement, partly on account of barriers that hinder integrated work between researchers and policy-makers. This paper describes a “policy effectiveness–feasibility loop” (PEFL) that brings together epidemiological modelling, local situation analysis and option appraisal to foster collaboration between researchers and policy-makers. Epidemiological modelling explores the determinants of trends in disease and the potential health benefits of modifying them. Situation analysis investigates the current conceptualization of policy, the level of policy awareness and commitment among key stakeholders, and what actually happens in practice, thereby helping to identify policy gaps. Option appraisal integrates epidemiological modelling and situation analysis to investigate the feasibility, costs and likely health benefits of various policy options. The authors illustrate how PEFL was used in a project to inform public policy for the prevention of cardiovascular diseases and diabetes in four parts of the eastern Mediterranean. They conclude that PEFL may offer a useful framework for researchers and policy-makers to successfully work together to generate evidence-based policy, and they encourage further evaluation of this approach

Analytical Exploration of Potential Pathways by which Diabetes Mellitus Impacts Tuberculosis Epidemiology.

We aimed to develop a conceptual framework of diabetes mellitus (DM) effects on tuberculosis (TB) natural history and treatment outcomes, and to assess the impact of these effects on TB-transmission dynamics. The model was calibrated using TB data for India. A conceptual framework was developed based on a literature review, and then translated into a mathematical model to assess the impact of the DM-on-TB effects. The impact was analyzed using TB-disease incidence hazard ratio (HR) and population attributable fraction (PAF) measures. Evidence was identified for 10 plausible DM-on-TB effects. Assuming a flat change of 300% (meaning an effect size of 3.0) for each DM-on-TB effect, the HR ranged between 1.0 (Effect 9-Recovery) and 2.7 (Effect 2-Fast progression); most effects did not have an impact on the HR. Meanwhile, TB-disease incidence attributed directly and indirectly to each effect ranged between -4.6% (Effect 7-TB mortality) and 34.5% (Effect 2-Fast progression). The second largest impact was for Effect 6-Disease infectiousness at 29.9%. In conclusion, DM can affect TB-transmission dynamics in multiple ways, most of which are poorly characterized and difficult to assess in epidemiologic studies. The indirect (e.g. onward transmission) impacts of some DM-on-TB effects are comparable in scale to the direct impacts. While the impact of several effects on the HR was limited, the impact on the PAF was substantial suggesting that DM could be impacting TB epidemiology to a larger extent than previously thought

Effect of subsidies on healthful consumption: a protocol for a systematic review update.

INTRODUCTION: The prevalence of diet-related non-communicable diseases (NCDs) are rapidly increasing in most parts of the world. In order to ameliorate the related public health burden, evidence-informed policies to improve diet need to be implemented. Financial subsidies that promote healthful consumption patterns have the potential to reduce NCD risk and may also reduce inequality if targeted at those of low socio-economic position. This protocol is for an updated systematic review of such evidence. METHODS AND ANALYSIS: A systematic search strategy will be used to identify publications on fiscal intervention studies indexed in Embase, CINAHL, Web of Science, EconLit and PubMed in between January 2013 to February 2019. Two reviewers will independently sift identified citations using prespecified inclusion and exclusion criteria to inform full-text review. The outcomes of interest are: consumption patterns (% change in targeted items and in overall dietary patterns), purchasing patterns (% change) or body mass index. Pretested data capture forms will be used for double data extraction. Any inconsistencies in citation sifting or data extraction will be resolved by a third investigator and study authors will be contacted if needed. Systematic searches will be supplemented by reference checking of key articles. Study quality will be assessed and a narrative summary of findings will be produced. Meta-analyses and exploration of heterogeneity will be completed if appropriate. ETHICS AND DISSEMINATION: The review aims to strengthen findings of the primary studies it incorporates. It will synthesise existing published aggregated patient data and only present further aggregate data. Given this, no concerns are held relating to confidentiality and informed consent due to re-use of patient data.If publications or data with ethical concerns are identified, they will be excluded from the review.Results of the systematic review will be published in full and authors will engage directly with research audiences and key stakeholders to share findings. PROSPERO REGISTRATION NUMBER: CRD42019125013

Editorial: Can't get you out of my head: brain-body interactions in perseverative cognition

Perseverative cognition represents a prototypical example of how our internal thoughts can impact our psychological and physical health, as if we were facing an actual environmental stressor (Brosschot et al., 2006). The mechanisms involved—together with other emblematic examples like the placebo effect—provide clear evidence for brain-body interaction. This collection of articles presents recent advances in our understanding of perseverative cognition that have arisen from the integration of multidisciplinary approaches encompassing cognitive and clinical psychology, affective neuroscience, and autonomic physiology. These advances carry with them the promise of more effective treatments to mitigate the negative consequences of maladaptive perseverative cognition on health and well-being

Euclidean Distances, soft and spectral Clustering on Weighted Graphs

We define a class of Euclidean distances on weighted graphs, enabling to perform thermodynamic soft graph clustering. The class can be constructed form the "raw coordinates" encountered in spectral clustering, and can be extended by means of higher-dimensional embeddings (Schoenberg transformations). Geographical flow data, properly conditioned, illustrate the procedure as well as visualization aspects.Comment: accepted for presentation (and further publication) at the ECML PKDD 2010 conferenc

The Finiteness Requirement for Six-Dimensional Euclidean Einstein Gravity

The finiteness requirement for Euclidean Einstein gravity is shown to be so stringent that only the flat metric is allowed. We examine counterterms in 4D and 6D Ricci-flat manifolds from general invariance arguments.Comment: 15 pages, Introduction is improved, many figures(eps