Why may reduced order models based on global modes not work for closed loop control?

National audienceIn this article, we use a reduced model based on global modes to stabilize a globally unstable cavity flow. We show that although the full-state control is successful, the partial state controller cannot stabilize the perturbations. We introduce the notion of full-state measurement control to analyze this failure and show that it is due to a lack of information of the reduced model about the stable subspace. In particular, the input-output behavior is identified as the key parameter to be captured by the reduced model. A criterion is then derived in order to select the stable global modes which are likely to contribute to the input-output behavior. These critical modes are found to be impossible to compute because of the non-normality of the Navier-Stokes operator, which leads us to the conclusion that global modes are not suitable for control based reduced models

Closed-loop control of an open cavity flow using reduced-order models

International audienceThe control of separated fluid flow by reduced-order models is studied using the two-dimensional incompressible flow over an open square cavity at Reynolds numbers where instabilities are present. Actuation and measurement locations are taken on the upstream and downstream edge of the cavity. A bi-orthogonal projection is introduced to arrive at reduced-order models for the compensated problem. Global modes, proper orthogonal decomposition (POD) modes and balanced modes are used as expansion bases for the model reduction. The open-loop behaviour of the full and the reduced systems is analysed by comparing the respective transfer functions. This analysis shows that global modes are inadequate to sufficiently represent the inputoutput behaviour whereas POD and balanced modes are capable of properly approximating the exact transfer function. Balanced modes are far more efficient in this process, but POD modes show superior robustness. The performance of the closed-loop system corroborates this finding: while reduced-order models based on POD are able to render the compensated system stable, balanced modes accomplish the same with far fewer degrees of freedom. © 2009 Cambridge University Press

Magnesium and hypertension in old age

Hypertension is a complex condition in which various actors and mechanisms combine, resulting in cardiovascular and cerebrovascular complications that today represent the most fre-quent causes of mortality, morbidity, disability, and health expenses worldwide. In the last decades, there has been an exceptional amount of experimental, epidemiological, and clinical studies confirm-ing a close relationship between magnesium deficit and high blood pressure. Multiple mechanisms may help to explain the bulk of evidence supporting a protective effect of magnesium against hypertension and its complications. Hypertension increases sharply with advancing age, hence older persons are those most affected by its negative consequences. They are also more frequently at risk of magnesium deficiency by multiple mechanisms, which may, at least in part, explain the higher frequency of hypertension and its long-term complications. The evidence for a favorable effect of magnesium on hypertension risk emphasizes the importance of broadly encouraging the intake of foods such as vegetables, nuts, whole cereals and legumes, optimal dietary sources of magnesium, avoiding processed food, which are very poor in magnesium and other fundamental nutrients, in order to prevent hypertension. In some cases, when diet is not enough to maintain an adequate magnesium status, magnesium supplementation may be of benefit and has been shown to be well tolerated

Magnesium in Type 2 Diabetes Mellitus, Obesity, and Metabolic Syndrome

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Magnesium in Aging, Health and Diseases

Several changes of magnesium (Mg) metabolism have been reported with aging, including diminished Mg intake, impaired intestinal Mg absorption and renal Mg wasting. Mild Mg deficits are generally asymptomatic and clinical signs are usually non-specific or absent. Asthenia, sleep disorders, hyperemotionality, and cognitive disorders are common in the elderly with mild Mg deficit, and may be often confused with age-related symptoms. Chronic Mg deficits increase the production of free radicals which have been implicated in the development of several chronic age-related disorders. Numerous human diseases have been associated with Mg deficits, including cardiovascular diseases, hypertension and stroke, cardio-metabolic syndrome and type 2 diabetes mellitus, airways constrictive syndromes and asthma, depression, stress-related conditions and psychiatric disorders, Alzheimer's disease (AD) and other dementia syndromes, muscular diseases (muscle pain, chronic fatigue, and fibromyalgia), bone fragility, and cancer. Dietary Mg and/or Mg consumed in drinking water (generally more bioavailable than Mg contained in food) or in alternative Mg supplements should be taken into consideration in the correction of Mg deficits. Maintaining an optimal Mg balance all through life may help in the prevention of oxidative stress and chronic conditions associated with aging. This needs to be demonstrated by future studies

Osteoporosis in men: a case report

Osteoporosis in men is frequently not considered, underdiagnosed and often undertreated. In contrast with osteoporosis occurring in women, the genesis is frequently secondary (30-60%) with a complex diagnostic approach. A careful anamnesis and physical examination associated with laboratory and instrumental evaluation are necessary for an accurate diagnosis. The clinical case presented concerns a 70-year-old man with negative family history for osteoporosis and a personal history of depression, HBV carrier, and chronic obstructive pulmonary disease (COPD) in a heavy ex-smoker with history of alcoholism. The comprehensive geriatric evaluation allowed us to diagnose a multifactorially secondary osteoporosis associated to osteomalacia probably generated by the combination of alcohol abuse with consequent severe malnutrition, heavy smoking and COPD, physical inactivity and rapid weight loss

Anthocyanin variation in individual 'Shiraz' berries as affected by exposure and position on the rachis

This study was done on 'Shiraz'/Richter 99 grapes with the intention to define the variation of skin anthocyanin content in a single berry. The effects of berry position (on the rachis), berry exposure, berry weight category, part of the skin of a single berry, and their interactions, were analysed. The anthocyanin concentration of externally facing berries decreased and that of the internally facing berries increased from the apical part to the basal part of the bunch. Highest values were recorded in internally facing berries and lowest values in the externally facing (exposed) berries, of the basal rachis area. Anthocyanin values of small berries seemed to decrease from the apical part of the rachis to the basal part, whereas those of the larger berries generally increased. Anthocyanin distribution in the skin of a single berry was similar for all the berry weight categories. The median concentric layer of the berry showed the highest anthocyanin concentration. The study showed significant intra-berry variation, indicating that even at full ripeness stage there is still variation in every single smaller or larger berry. The results highlighted the very complicated management challenges to grape producers to increase bunch uniformity in quantity and quality.

Presbyphagia and dysphagia in old age

Although presbyphagia is a clinically relevant problem among elderly population, possibly leading to dysphagia in old age, it remains a still underestimated health condi-tion. The present review analyzes swallow-ing related anatomical and functional changes during aging, both in healthy peo-ple and in those affected by dysphagia. First of all, dysphagia in old people must not be confused with presbyphagia. To distinguish these two different conditions, a correct def-inition of both should be considered. Subsequently, a comprehensive evaluation including instrumental analysis should be carried out. The aim of this narrative review is to analyze the current knowledge of this clinical condition and to provide the state of art to clinicians. A systematic PubMed research on dysphagia in the elderly was conducted and most relevant and most recent references were manually screened and selected. The aim of a correct diagnosis is to enable the choice of a correct interven-tion in order to prevent and treat complica-tions of dysphagia, such as ab ingestis pneumonia and malnutrition. Moreover, the assessment, diagnosis and therapy of dys-phagia/presbyphagia should include the intervention of different specialists

Experimental setup and procedure for the measurement of the 7Be(n,p)7Li reaction at n_TOF

Following the completion of the second neutron beam line and the related experimental area (EAR2) at the n_TOF spallation neutron source at CERN, several experiments were planned and performed. The high instantaneous neutron flux available in EAR2 allows to investigate neutron induced reactions with charged particles in the exit channel even employing targets made out of small amounts of short-lived radioactive isotopes. After the successful measurement of the 7Be(n,) cross section, the 7Be(n,p)7Li reaction was studied in order to provide still missing cross section data of relevance for Big Bang Nucleosynthesis (BBN), in an attempt to find a solution to the cosmological Lithium abundance problem. This paper describes the experimental setup employed in such a measurement and its characterization.Séptimo Programa Marco de la Comunidad Europea de la Energía Atómica (Euratom)-Proyecto CHANDA (No. 605203)Narodowe Centrum Nauki (NCN)-UMO-2012/04/M/ST2/00700-UMO-2016/22/M/ST2/00183Croatian Science Foundation-HRZZ 168

Impact of mediterranean diet on chronic non-communicable diseases and longevity

The average life expectancy of the world population has increased remarkably in the past 150 years and it is still increasing. A long life is a dream of humans since the beginning of time but also a dream is to live it in good physical and mental condition. Nutrition research has focused on recent decades more on food combination patterns than on individual foods/nutrients due to the possible synergistic/antagonistic effects of the components in a dietary model. Various dietary patterns have been associated with health benefits, but the largest body of evidence in the literature is attributable to the traditional dietary habits and lifestyle followed by populations from the Mediterranean region. After the Seven Countries Study, many prospective observational studies and trials in diverse populations reinforced the beneficial effects associated with a higher adherence to the Mediterranean diet in reference to the prevention/management of age-associated non-communicable diseases, such as cardiovascular and metabolic diseases, neurodegenerative diseases, cancer, depression, respiratory diseases, and fragility fractures. In addition, the Mediterranean diet is ecologically sustainable. Therefore, this immaterial world heritage constitutes a healthy way of eating and living respecting the environment