The multi-physics improved quasi-static method - Application to a neutronics-thermomechanics coupling

International audienceThe quasi-static method is widely used for space- and time-dependent neutron transport problems. It is based on the factorization of the flux into the product of two functions, an “amplitude” depending only on time and a “shape” which depends on all variables. Thanks to this factorization, long time-steps can be used for the computation of the shape, leading to a substantial reduction of the calculation time. Two algorithms, based on the quasi-static factorization, can be found in the literature: the “Improved Quasi-static Method” (IQM), and the “Predictor-Corrector Quasi-static Method” (PCQM).In this paper we show, on the example of the Godiva experiment, that the IQM algorithm can be easily adapted to multi-physics simulations. Moreover, most of the common coupling or time-step control strategies are compatible with this algorithm and we test some of them here. In particular, a technique taken from existing codes with point-kinetic modules and based on feedback coefficients is found, in our case, to be especially efficient and gives precise and fast results. This shows that the multi-physics IQM presented in this paper is compatible with these existing codes, and may be a way to couple them with neutron transport solvers

Empirical antibiotic therapy modalities for Enterobacteriaceae bloodstream infections in older patients and their impact on mortality: a multicentre retrospective study

International audiencePurpose: Enterobacteriaceae (EB) bloodstream infections (BSI) are frequent and serious in older patients. Physicians are faced with the dilemma of prescribing early appropriate empirical antibiotics to limit the risk of death, and sparing broad-spectrum antibiotic prescription. The aim of the study was to assess the rate of appropriate empirical antibiotics prescription to treat EB BSI in older patients and its impact on survival.Methods: This study conducted in 49 centres enrolled retrospectively up to the 10 last consecutive patients aged 75 years and over and treated for EB BSI. Factors related to in-hospital death were investigated using logistic regression.Results: Among the 487 enrolled patients (mean age 86 ± 5.9 years), 70% had at least one risk factor of being infected by third-generation cephalosporins (3GC)-resistant strain; however, only 13.8% of EB strains were resistant to 3GC. An empirical antimicrobial treatment was initiated for 418 patients (85.8%), and for 86% (n = 360/418) of them, it was considered appropriate. In-hospital mortality was 12.7% (n = 62) and was related to the severity of infection (OR 3.17, CI 95% 1.75-5.75), while a urinary portal of entry was protective (OR 0.34, CI 95% 0.19-0.60). Neither the absence of nor inappropriate empirical antibiotics prescription was associated with increased mortality.Conclusion: While patients enrolled in this study were at risk of being infected by multidrug-resistant bacteria, yet mainly treated with 3GC, empirical antibiotics prescription was appropriate in most cases and did not influence mortality

European Academy for medicine of ageing session participants' report on malnutrition assessment and diagnostic methods; an international survey

Introduction: Malnutrition and nutrition-related diseases are associated with hospital admissions, disability, institutionalization, and mortality in older people. Specialists in Geriatric Medicine and nutrition evaluate nutritional status as part of the comprehensive geriatric assessment; however, malnutrition still remains under-recognized and under-managed. Our survey explored nutrition assessment approaches used in daily clinical practice by geriatricians across Europe. Methods: A 19-item survey on methods and instruments for malnutrition assessment in geriatric settings, and details of any national guidelines, was sent to 40 postgraduate fellows of the European Academy of Medicine of Aging (EAMA, 2017-2019 class). Results: Thirty-six of the 40 eligible EAMA participants, representing 14 European countries, responded. In clinical practice, MNA and MNA-SF were most frequently used for screening (44.1%, 52.9%, respectively) and diagnosing (45.7%, 40.0%) malnutrition. Weight loss (n = 36, 100%), body mass index (n = 30, 85.7%), and low energy/food intake (n = 27, 77.1%) were the most frequent clinical variables considered. The absolute and relative amount of weight loss, and over what time period, varied widely. These routinely considered clinical factors contribute to validated GLIM, ASPEN-AND and ESPEN criteria for diagnosis of malnutrition, but these criteria were seldom used (GLIM = 0%, ASPEN = 0%; n = 9, ESPEN = 25.7%). National guidelines were available in 9 of the 14 countries, and generally recommended MNA and MNA-SF for community-dwelling and hospitalized older patients. Albumin was often suggested as a nutritional marker. Conclusions: Nutritional assessment is systematically performed in geriatrics; but differs widely among geriatricians and countries. Harmonizing guidelines with the new international consensus might provide best-evidence care for older people across Europe