Time-series forecasting using manifold learning, radial basis function interpolation, and geometric harmonics.

We address a three-tier numerical framework based on nonlinear manifold learning for the forecasting of high-dimensional time series, relaxing the "curse of dimensionality" related to the training phase of surrogate/machine learning models. At the first step, we embed the high-dimensional time series into a reduced low-dimensional space using nonlinear manifold learning (local linear embedding and parsimonious diffusion maps). Then, we construct reduced-order surrogate models on the manifold (here, for our illustrations, we used multivariate autoregressive and Gaussian process regression models) to forecast the embedded dynamics. Finally, we solve the pre-image problem, thus lifting the embedded time series back to the original high-dimensional space using radial basis function interpolation and geometric harmonics. The proposed numerical data-driven scheme can also be applied as a reduced-order model procedure for the numerical solution/propagation of the (transient) dynamics of partial differential equations (PDEs). We assess the performance of the proposed scheme via three different families of problems: (a) the forecasting of synthetic time series generated by three simplistic linear and weakly nonlinear stochastic models resembling electroencephalography signals, (b) the prediction/propagation of the solution profiles of a linear parabolic PDE and the Brusselator model (a set of two nonlinear parabolic PDEs), and (c) the forecasting of a real-world data set containing daily time series of ten key foreign exchange rates spanning the time period 3 September 2001-29 October 2020.

Delayed Double Treatment with Adult-Sourced Adipose-Derived Mesenchymal Stem Cells Increases Striatal Medium-Spiny Neuronal Number, Decreases Striatal Microglial Number, and Has No Subventricular Proliferative Effect, after Acute Neonatal Hypoxia-Ischemia in Male Rats.

Perinatal hypoxia-ischemia (HI) is a major cause of striatal injury. Delayed post-treatment with adult-sourced bone marrow-derived mesenchymal stem cells (BMSCs) increased the absolute number of striatal medium-spiny neurons (MSNs) following perinatal HI-induced brain injury. Yet extraction of BMSCs is more invasive and difficult compared to extraction of adipose-derived mesenchymal stem cells (AD-MSCs), which are easily sourced from subcutaneous tissue. Adult-sourced AD-MSCs are also superior to BMSCs in the treatment of adult ischemic stroke. Therefore, we investigated whether delayed post-treatment with adult-sourced AD-MSCs increased the absolute number of striatal MSNs following perinatal HI-induced brain injury. This included investigation of the location of injected AD-MSCs within the brain, which were widespread in the dorsolateral subventricular zone (dlSVZ) at 1 day after their injection. Cells extracted from adult rat tissue were verified to be stem cells by their adherence to tissue culture plastic and their expression of specific 'cluster of differentiation' (CD) markers. They were verified to be AD-MSCs by their ability to differentiate into adipocytes and osteocytes in vitro. Postnatal day (PN) 7/8, male Sprague-Dawley rats were exposed to either HI right-sided brain injury or no HI injury. The HI rats were either untreated (HI + Diluent), single stem cell-treated (HI + MSCs×1), or double stem cell-treated (HI + MSCs×2). Control rats that were matched-for-weight and litter had no HI injury and were treated with diluent (Uninjured + Diluent). Treatment with AD-MSCs or diluent occurred either 7 days, or 7 and 9 days, after HI. There was a significant increase in the absolute number of striatal dopamine and cyclic AMP-regulated phosphoprotein (DARPP-32)-positive MSNs in the double stem cell-treated (HI + MSCs×2) group and the normal control group compared to the HI + Diluent group at PN21. We therefore investigated two potential mechanisms for this effect of double-treatment with AD-MSCs. Specifically, did AD-MSCs: (i) increase the proliferation of cells within the dlSVZ, and (ii) decrease the microglial response in the dlSVZ and striatum? It was found that a primary repair mechanism triggered by double treatment with AD-MSCs involved significantly decreased striatal inflammation. The results may lead to the development of clinically effective and less invasive stem cell therapies for neonatal HI brain injury.

Electronic registry for the management of childhood obesity in Greece.

BACKGROUND: Obesity in childhood and adolescence represents a major health problem in our century. In Greece, more than 30%-35% of children and adolescents are either overweight or obese. MATERIALS AND METHODS: Using information and communication technologies, we developed a "National Registry for the Prevention and Management of Overweight and Obesity in Childhood and Adolescence" for guidance and training of Pediatricians and General Practitioners. The application supports interoperability with other national infrastructures and multi-layered security spanning preventive, detective and administrative controls. The Patient Summary Dataset includes information on medical history, family history, medications, immunizations, clinical examination and laboratory findings and appointment booking service. RESULTS: The application was launched in September 2015 and is accessible by: http://app.childhood-obesity.gr/. Based on the data that the doctor registers, the system calculates a personalized therapeutic algorithm that provides information on diet, physical exercise and sleep, as well as guidance on laboratory investigations and referral to specialized centres. A pilot study performed in 1270 children and adolescents indicated that using this system resulted in a reduction in obesity rates by 30% and overweight rates by 35% within 1 year. CONCLUSIONS: This National e-Health System appears to be effective in the management of overweight and obesity in childhood and adolescence.

Exploring the effects of attitudinal and perception characteristics on drinking and driving non-compliant behaviour.

The objective of this paper is to examine a number of factors (observed and latent) that might have a causal effect on drinking and driving (D&D) behaviour. Face-to-face surveys were conducted among patrons at bars and cafeterias and 305 valid questionnaires were filled. A confirmatory factor analysis was performed so as to identify the latent constructs and a mixed structural equation model was developed. From the analysis it came up that non-compliant behaviour of D&D is limited at older ages, also associated with high levels of income and car availability. Though men are consuming more alcohol, women seem to be more prone in driving under the influence (DUI) of alcohol. Furthermore, it was found that people who strongly support the examined interventions in the study (e.g. better enforcement, more traffic safety campaigns, stricter penalties) are more unlikely to drive after drinking compare to those who have some objections. Finally, it was not found any statistically significant relation between individuals' level of awareness and D&D behaviour.

Driver behaviour, dilemma zone and safety effects at urban signalized intersections in Greece.

Driving behaviour at signalized intersections is one of the main factors contributing to the safety level of such entities. This behaviour, with respect to yellow signal obedience or violation, is examined at a signalized intersection in Thessaloniki, Greece. The data, collected for the study purposes, include vehicles' speeds and distance from stop line when exposed to yellow light, gender and age group of drivers as well as reaction of Platoon leaders and first followers. Drivers were grouped into three categories, namely conservative, normal and aggressive, according to their behaviour at the intersection, the existence of a dilemma or option zone and their initial approaching speed. A binary choice model was also developed relating the probability of stopping at the STOP line or crossing it as a function of approach speed, distance from intersection, gender, age group and the existence or not of a dilemma zone. The findings of this research indicate that a large percentage of drivers facing the yellow signal are caught in a dilemma zone due to high approaching speeds and exercise an aggressive behaviour. The distribution of drivers into the three categories changes with differing assumptions pertaining to the factors affecting the calculation of safe stopping distance and critical crossing distance as well as speed thresholds for determining a priori aggressive behaviour. The research concludes that aggressive drivers represent a high percentage of all drivers and measures towards improving driving behaviour and/or reducing vehicles' speeds are required.