An IMEX-DG solver for atmospheric dynamics simulations with adaptive mesh refinement

We present an accurate and efficient solver for atmospheric dynamics simulations that allows for non-conforming mesh refinement. The model equations are the conservative Euler equations for compressible flows. The numerical method is based on an $h-$adaptive Discontinuous Galerkin spatial discretization and on a second order Additive Runge Kutta IMEX method for time discretization, especially designed for low Mach regimes. The solver is implemented in the framework of the $deal.II$ library, whose mesh refinement capabilities are employed to enhance efficiency. A number of numerical experiments based on classical benchmarks for atmosphere dynamics demonstrate the properties and advantages of the proposed method

A seamless, extended DG approach for advection-diffusion problems on unbounded domains

We propose and analyze a seamless extended Discontinuous Galerkin (DG) discretization of advection-diffusion equations on semi-infinite domains. The semi-infinite half line is split into a finite subdomain where the model uses a standard polynomial basis, and a semi-unbounded subdomain where scaled Laguerre functions are employed as basis and test functions. Numerical fluxes enable the coupling at the interface between the two subdomains in the same way as standard single domain DG interelement fluxes. A novel linear analysis on the extended DG model yields unconditional stability with respect to the P\'eclet number. Errors due to the use of different sets of basis functions on different portions of the domain are negligible, as highlighted in numerical experiments with the linear advection-diffusion and viscous Burgers' equations. With an added damping term on the semi-infinite subdomain, the extended framework is able to efficiently simulate absorbing boundary conditions without additional conditions at the interface. A few modes in the semi-infinite subdomain are found to suffice to deal with outgoing single wave and wave train signals more accurately than standard approaches at a given computational cost, thus providing an appealing model for fluid flow simulations in unbounded regions.Comment: 27 pages, 8 figure

Short and medium term functional capacity after single cycle of controlled physical training in subjects with claudication

BACKGROUND. Previous studies have shown the positive effect of exercise rehabilitation in patients with claudication, but uncertainties remain surrounding the optimal exercise program strategy and the persistence of the benefits over time. The purpose of the present study has been to prospectively assess the feasibility of short-course intensive supervised exercise training beyond pain threshold and to verify the maintenance of walking capacity during a medium term follow-up. METHODS. Ninety patients with intermittent claudication due to peripheral artery disease were enrolled in a supervised intensive exercise training. Seventy six of them (67 ± 7 years, 64 male and 12 female, 48 with bilateral claudication) performed a graded treadmill testing at baseline and after 3 months. Sixty patients completed also a specific questionnaire (Walking Impairement Questionnarie). After a mean follow-up of 2.6 years, fifty six patients repeated treadmill testing and 24 patients repeated the questionnaire. RESULTS. After training, the patients showed a 91% and 53% increase in the initial and absolute claudication distance time, respectively (p=0.0000). At follow-up there was no change in the initial claudication distance time, whereas absolute claudication distance time was reduced by only 13% (p=0.0001). All items of the questionnaire showed a statistically significant improvement after training (from 30 to 71%) and remained unchanged at follow-up. Sixty seven percent of the patients were considered responder, 15% partial responder and 18% no-responder to exercise training, whereas at follow- up these percentages were 55%, 13% and 32%, respectively. These results after training and at follow-up were independent from age, sex, smoke, hypertension, coronary artery disease and diabetes. CONCLUSIONS. Our findings confirm that a short supervised exercise therapy in the form of walking out over pain threshold is effective in maximizing the walking time of the majority of patients with intermittent claudication, independently of demographic data and their associated cardiac risk factors or comorbidities. After a mean follow-up of 2.6 years there was only a minor reduction of absolute claudication distance time and no modification of initial claudication distance time and questionnaire’s score, despite the fact that none of these patients were contacted by the rehabilitation centre after their physical training period

Validity of Italian version of the child perceptions questionnaire (CPQ11-14)

BACKGROUND: The Child Perceptions Questionnaire (CPQ(11-14)) is the most commonly used indicator of child oral health-related quality of life (OHRQoL), and its validity and reliability have been studied both in English and in other linguistic contexts. The aim of this study was to develop a CPQ(11-14) for use in Italy and to test its validity in a random sample of fourteen year-old Italian adolescents. METHODS: Once the CPQ(11-14)was translated into Italian and adapted for an Italian public, five hundred sixty-one adolescents were recruited for testing. Parents rated their social status; the children/adolescents were administered the questionnaire and underwent a dental examination during which their dental status was taken and recorded. Cronbach's alpha was used to assess the questionnaire’s internal consistency. Spearman's correlation coefficients were calculated to assess construct validity between the total and subscale scores and the respondents’ global ratings on oral health and well-being. Discriminant validity was analysed using the Kruskal-Wallis or Mann–Whitney tests in groups defined by gender, social position, caries experience and previous or no orthodontic treatment. RESULTS: The mean score on the CPQ(11-14) was 15.4 (SD=11.9), and the scores on all the domains were found to be highly skewed. Cronbach's alpha ranged from 0.85 to 0.90. The global ratings on oral health and well-being were correlated to the total score and to the sub-scores except for those regarding the functional limitations. There were significant differences in the two genders, in the groups that had already or had not yet undergone orthodontic treatment, and in the social classification groups, while the difference between those who had and those who did not have caries experience did not reach statistical significance. CONCLUSIONS: The Italian version of the CPQ(11-14) appears to be a reliable, valid instrument for Italian children/adolescents

Association of renin-angiotensin-aldosterone system inhibitors with best COVID-19 outcomes in a diabetic population of the Veneto region (north-east Italy): A lesson for endemic phase?

Background and aims: Diabetes mellitus is a prevalent chronic disease in patients who die of COVID-19. The aim of this study was to investigate the clinical and metabolic characteristics of diabetic patients with COVID-19 during the pre-vaccination phase. Methods and results: A retrospective cohort study was conducted from February 2020 to February 2021 to examine the clinical and metabolic profiles of unvaccinated diabetic patients affected by COVID-19. Data were collected from claim databases, hospital discharge records, and clinical records within a healthcare district located in northeastern Italy with a population of 936,000. Potential prognostic indicators including sex, age, Body Mass Index (BMI), duration and type of diabetes, metabolic control, and the use of antidiabetic, antihypertensive, lipid-lowering, and antiplatelet therapies were investigated. For hospitalized patients, additional variables were recorded, such as length of hospital stay, blood pressure at admission, comorbidities, D-dimer levels, blood glucose (BG), in-hospital insulin and corticosteroid therapies, requirement for mechanical ventilation (i.e., orotracheal or tracheostomy), admission to the Intensive Care Unit (ICU), and mortality. Diabetic patients hospitalized for COVID-19 with a poorer prognosis were characterized by advanced age, longer diabetes duration, hypertension, higher usage of sulfonylureas, and lower usage of dietotherapy alone, metformin, Glucagon-Like Peptide-1 Receptor agonists (GLP1-Ra), and Renin-Angiotensin-Aldosterone System inhibitors (RAAS-i). Conclusion: Considering the potential for COVID-19 to become endemic, special care should be taken in managing older diabetic patients' treatments

Infection Rates and Impact of Glucose Lowering Medications on the Clinical Course of COVID-19 in People with Type 2 Diabetes: A Retrospective Observational Study

Purpose: Diabetes is a risk factor for COVID-19 severity, but the role played by glucose lowering medications (GLM) is still unclear. The aim of this study was to assess infection rates and outcomes of COVID-19 (hospitalization and mortality) in adults with diabetes assisted by the Local Health Unit of Padua (North-East Italy) according to the ongoing GLM. Patients and methods: People with diabetes were identified using administrative claims, while those with SARS-CoV-2 infection were detected by cross referencing with the local COVID-19 surveillance registry. A multivariate logistic regression model was used to verify the association between GLM classes and the outcome. Results: SARS-CoV-2 infection rates were marginally but significantly higher in individuals with diabetes as compared to those without diabetes (RR 1.04, p = 0.043), though such relative 4% increase may be irrelevant from a clinical and epidemiological perspective. 1923 individuals with GLM-treated diabetes were diagnosed with COVID-19; 456 patients were hospitalized and 167 died. Those treated with insulin had a significantly higher risk of hospitalizations for COVID-19 (OR 1.48 p < 0.01) as were those treated with sulphonylureas/glinides (OR 1.34, p = 0.02). Insulin use was also significantly associated with higher mortality (OR 1.90, p < 0.01). Use of metformin was significantly associated with lower death rates (OR 0.62, p = 0.02). The association of other GLM classes with the outcome was not significant. Conclusion: Diabetes does not appear to modify the risk of SARS-CoV-2 infection in a clinically meaningful way, but strongly increases the rates of hospitalization and death. Insulin use was associated with worse outcomes, whereas metformin use was associated with lower mortality

Resilience and fault tolerance in high-performance computing for numerical weather and climate prediction

Progress in numerical weather and climate prediction accuracy greatly depends on the growth of the available computing power. As the number of cores in top computing facilities pushes into the millions, increased average frequency of hardware and software failures forces users to review their algorithms and systems in order to protect simulations from breakdown. This report surveys hardware, application-level and algorithm-level resilience approaches of particular relevance to time-critical numerical weather and climate prediction systems. A selection of applicable existing strategies is analysed, featuring interpolation-restart and compressed checkpointing for the numerical schemes, in-memory checkpointing, user-level failure mitigation and backup-based methods for the systems. Numerical examples showcase the performance of the techniques in addressing faults, with particular emphasis on iterative solvers for linear systems, a staple of atmospheric fluid flow solvers. The potential impact of these strategies is discussed in relation to current development of numerical weather prediction algorithms and systems towards the exascale. Trade-offs between performance, efficiency and effectiveness of resiliency strategies are analysed and some recommendations outlined for future developments