Mixed formulation for linear viscoelasticity

openL'obbiettivo della tesi è arrivare ad una formulazione mista del problema viscoelastico passando per uno studio intermedio del problema elastico nel caso statico. Per raggiungere questo obbiettivo si è fatto uso dell'analisi convessa, in particolare, della trasformata di Legendre

Outlier admissions of medical patients: Prognostic implications of outlying patients. The experience of the Hospital of Mestre

ABSTRACT The admission of a patient in wards other than the appropriate ones, known as the patient outlying phenomenon, involves both Medicine and Geriatric Units of many Hospitals. The aims were to learn more about the prognosis of the outlying patients, we investigated 3828 consecutive patients hospitalized in Medicine and Geriatrics of our hub Hospital during the year 2012. We compared patients\u2019 mean hospital length of stay, survival, and early readmission according to their outlying status. The mean hospital length of stay did not significantly differ between the two groups, either for Medicine (9.8 days for outliers and 10.0 for in-ward) or Geriatrics (13.0 days for both). However, after adjustment for age and sex, the risk of death was about twice as high for outlier patients admitted into surgical compared to medical areas (hazard ratio 1.8, 1.2-2.5 95% confidence interval). Readmission within 90 days from the first discharge was more frequent for patients admitted as outliers (26.1% vs 14.2%, P<0.0001). We highlight some critical aspects of an overcrowded hospital, as the shortage of beds in Medicine and Geriatrics and the potential increased clinical risk denoted by deaths or early readmission for medical outlier patients when assigned to inappropriate wards. There is the need to reorganize beds allocation involving community services, improve in-hospital bed management, an extent diagnostic procedures for outlier patients admitted in nonmedical wards

METODICHE DI VALUTAZIONE DELLA RIGIDITA\u2019 ARTERIOSA: IMPLICAZIONI CLINICHE NEL SOGGETTO ANZIANO

La distensibilit\ue0 dei vasi arteriosi si riduce con l\u2019et\ue0. Differenti metodiche per la misurazione della rigidit\ue0 arteriosa sono disponibili, anche nel soggetto anziano, quali la pressione differenziale, la velocit\ue0 dell\u2019onda di polso (PWV), l\u2019augmentation index (AI), il QKD e la systemic arterial compliance (SAC). Un\u2019aumentata rigidit\ue0 artertiosa, valutata con la PWVcf, \ue8 un fattore di rischio cardiovascolare indipendente ed \ue8 un indice di aterosclerosi subclinica. Ciascun componente della sindrome metabolica, quali obesit\ue0 addominale, dislipidemia, ipertensione arteriosa e iperglicemia, sono fattori di rischio CV indipendenti. E\u2019 stato dimostrato che il grasso addominale gioca un ruolo chiave nello sviluppo di malattie cardiovascolari, anche nell\u2019anziano. D\u2019altra parte \ue8 stato dimostrato il ruolo protettivo del tessuto adiposo periferico sul rischio CV. Solo pochi studi hanno valutato le relazioni tra distribuzione del grasso corporeo e rigidit\ue0 arteriosa nell\u2019anziano. Solo pochi studi inoltre hanno comparato diverse classificazioni di sindrome metabolica nel predire il danno vascolare subclinico. Perci\uf2 il primo scopo di tale tesi \ue8 stato quello di valutare le relazioni tra composizione corporea, sindrome metabolica, sue componenti e rigidit\ue0 arteriosa; il secondo scopo \ue8 stato quello di valutare quale dei valori di circonferenza vita considerati dalle classificazioni di IDF e NCEP fosse pi\uf9 accurato nell\u2019identificare il danno vascolare subclinico. In un sottogruppo di donne anziane inoltre \ue8 stato valutato il possibile ruolo protettivo del grasso periferico sul danno vascolare subclinico. Infine ulteriore scopo di questo studio \ue8 stato quello di confrontare in un sottogruppo di 52 soggetti due differenti metodiche di valutazione della rigidit\ue0 arteriosa, quali QKD e PWV nella valutazione del danno vascolare subclinico. In tutti i soggetti sono state valutate variabili antropometriche (peso, altezza, BMI, circonferenza vita), composizione corporea (massa grassa totale e tronculare, massa magra totale e appendicolare) misurata con Dual Energy X-Ray Absorptiometry (DXA), variabili metaboliche (colesterolo totale, colesterolo HDL e LDL, trigliceridi, glicemia ed emoglobina glicata) e pressione arteriosa. Tutti i soggetti sono stati inoltre sottoposti a tonometria arteriosa transcutanea per la rilevazione della velocit\ue0 dell\u2019onda di polso carotido-femorale (PWVcf) e dell\u2019onda di polso carotido-radiale (PWVcr). I soggetti affetti da SM, indipendentemente dalla definizione utilizzata (IDF o NCEP), presentavano valori di PWVcf, ma non di PWVcr, significativamente pi\uf9 elevati dei soggetti senza SM. Inoltre nel gruppo di soggetti con PWVcf maggiore di 12 m/sec, utilizzando il cut-off di circonferenza vita suggerito dalla IDF (80 cm nelle donne e 94 cm negli uomini) \ue8 stato identificato un maggior numero di soggetti con danno vascolare subclinico rispetto a quelli identificabili utilizzando i valori soglia del NCEP (88 cm nelle donne e 102 cm negli uomini). In un sottogruppo di soggetti di sesso femminile \ue8 emersa associazione negativa tra PWVcf e grasso periferico, dimostrando un possibile ruolo protettivo del grasso periferico sul danno vascolare subclinico. Infine, confrontando due diverse metodiche di valutazione di rigidit\ue0 arteriosa in un sottogruppo della nostra popolazione di studio di soggetti anziani, \ue8 emerso che sia il QKD che la PWVcf sono indici affidabili di rigidit\ue0 arteriosa correlati ai principali fattori di rischio CV, sebbene esplorino differenti segmenti arteirosi. Pertanto anche nel soggetto anziano \ue8 ipotizzabile l\u2019utilizzo congiunto di tali metodiche per identificare precocemente i soggetti con rischio CV subclinico.The compliance of the arteries declines with age. Different measures of arterial stiffness are available even in the elderly, such as pulse pressure, pulse wave velocity (PWV), augmentation index (AI), QKD and systemic arterial compliance (SAC). Increased arterial stiffness, assessed by carotid-femoral Pulse Wave Velocity, is an independent Cardiovascular Diseases risk factor and it has been recognized as an index of subclinical atherosclerosis. Each component of the metabolic syndrome (MS), such as abdominal fat, dyslipidemia, high blood pressure and hyperglycemia, are independent CV risk factors. It has been shown that body fat distribution, in terms of central adiposity, plays a key role in the development of CV diseases and mortality, even in the elderly. On the other hand it has been demonstrated the protective role of peripheral adipose tissue on the CV risk. However only a few studies evaluated the relationships between body fat distribution and arterial stiffness in the elderly. Moreover just a few studies compared different classifications of MS in terms of suclinical vascular damage\u2019s prediction. Therefore the first outcome of this study was to assess the relationships between body composition, metabolic syndrome (MS), its components and arterial stiffness in elderly healthy subjects of both sexes. As IDF and NCEP definition consider different waist circumference cut-off to identify abdominal obesity, the second aim of the present study was to evaluate which of waist circumference cut-off considered in IDF and NCEP MS definition was more accurate to identify subclinical vascular damage. In a subgroup of elderly women we wanted to evaluate the possible protective effect of peripheral adipose tissue on suclinical vascular damage. Finally another aim of this study was to compare in a subgroup of 52 elderly subjects two different measures of arterial stiffness such as QKD and PWV in the assessment of the subclinical vascular damage. In each subject we evaluated body mass index, waist circumference, systolic and diastolic blood pressure, metabolic variables, body composition by Dual energy X-ray Absorptiometry and arterial stiffness by carotid-femoral (PWVcf) and carotid-radial pulse wave velocity (PWVcr). PWVcf but not PWVcr was significantly higher in patients with MS than in those without MetS, independently of its definition (IDF or NCEP). By using more conservative values of waist cut-off, as suggested by IDF, it was possible to recognize higher percentage of subjects with subclinical vascular damage (PWV higher than 12 m/sec) than by using those suggested by NCEP. In a subgroup of women we found negative association between peripheral FM and PWVcf, showing a possibile protective role of the peripheral adopose tissue on suclinical vascular damage. Finally, comparing two different measures of arterial stiffness in a subgroup of our elderly subjects, we showed that both PWVcf and QKD 100-60 are good indexes of arterial compliance related to CV risk factors, eventhough they explore different arterial segments and should be probably used togheter to better identify subjects at higher subclinical CV risk

Indoor Point-to-Point Navigation with Deep Reinforcement Learning and Ultra-wideband

Indoor autonomous navigation requires a precise and accurate localization system able to guide robots through cluttered, unstructured and dynamic environments. Ultra-wideband (UWB) technology, as an indoor positioning system, offers precise localization and tracking, but moving obstacles and non-line-of-sight occurrences can generate noisy and unreliable signals. That, combined with sensors noise, unmodeled dynamics and environment changes can result in a failure of the guidance algorithm of the robot. We demonstrate how a power-efficient and low computational cost point-to-point local planner, learnt with deep reinforcement learning (RL), combined with UWB localization technology can constitute a robust and resilient to noise short-range guidance system complete solution. We trained the RL agent on a simulated environment that encapsulates the robot dynamics and task constraints and then, we tested the learnt point-to-point navigation policies in a real setting with more than two-hundred experimental evaluations using UWB localization. Our results show that the computational efficient end-to-end policy learnt in plain simulation, that directly maps low-range sensors signals to robot controls, deployed in combination with ultra-wideband noisy localization in a real environment, can provide a robust, scalable and at-the-edge low-cost navigation system solution.Comment: Accepted by ICAART 2021 - http://www.icaart.org

Irbesartan improves arterial compliance more than lisinopril

BACKGROUND Antihypertensive agents can reduce arterial stiffness. We hypothesized that an angiotensin receptor blocker (ARB) irbesartan and an angiotensin converting enzyme inhibitor (ACEI) lisinopril improved arterial compliance. METHODS A randomized, double-blind, double-dummy, controlled crossover trial. Fifteen hypertensive patients, mean age 65.5 +/- 8.9 years (mean +/- SD) were given irbesartan (150 to 300 mg/day) or lisinopril (10 to 20 mg/day) for 12 weeks and then crossed over for 12 weeks. Pulse wave velocity (PWV) in the carotid-femoral (CF), carotid-radial (CR), and femoral dorsalis-pedis (FD) were measured using a Complior((R)) PWV system. RESULTS After 12 weeks, systolic blood pressure (SBP) decreased from 162.4 +/- 12.9 to 134.5 +/- 14.8 with irbesartan and to 145.2 +/- 25 mmHg with lisinopril. Irbesartan and lisinopril reduced PWV (CF) in the elastic arterial system from 15.1 +/- 5 to 13.3 +/- 2.6 (p < 0.005) and to 14 +/- 4.7 (p < 0.05) m/s respectively (p = 0.345). Irbesartan reduced PWV (CR) and PWV (FD), whereas lisinopril did not. The difference between treatments was significant after SBP adjustment (p = 0.037 for PWV (CR) and p < 0.001 for PWV (FD)). CONCLUSIONS Irbesartan improved arterial compliance in elastic and muscular arteries, whereas lisinopril improved it only in elastic arteries

Ultra-low-power Range Error Mitigation for Ultra-wideband Precise Localization

Precise and accurate localization in outdoor and indoor environments is a challenging problem that currently constitutes a significant limitation for several practical applications. Ultra-wideband (UWB) localization technology represents a valuable low-cost solution to the problem. However, non-line-of-sight (NLOS) conditions and complexity of the specific radio environment can easily introduce a positive bias in the ranging measurement, resulting in highly inaccurate and unsatisfactory position estimation. In the light of this, we leverage the latest advancement in deep neural network optimization techniques and their implementation on ultra-low-power microcontrollers to introduce an effective range error mitigation solution that provides corrections in either NLOS or LOS conditions with a few mW of power. Our extensive experimentation endorses the advantages and improvements of our low-cost and power-efficient methodology

Natural Course of Aortic Stenosis in Older Subjects: Effects of COVID-19

Objective: Both aortic stenosis (AS) and COVID-19 affect the morbidity and mortality burden among older adults. The aim of the study was to examine whether aortic stenosis (AS) affects the prognosis after SARS-CoV-2 infection and whether COVID-19 affects AS prognosis, in a cohort of older adults hospitalized with and without COVID-19. Design: Observational study. Setting and participants: Patients admitted to 9 geriatric clinics in Stockholm from March 2020 to November&nbsp;2021. Methods: AS and COVID-19 diagnoses were identified by electronic health records; the outcomes were mortality at 30&nbsp;days and any time during a median follow-up of 630&nbsp;days. The associations between AS, COVID-19, and mortality were assessed by using Royston-Parmar models adjusting for age, sex, comorbidities, and admission waves. Results: Among 28,974 patients, 85 had concomitant AS and COVID-19, 529 had only AS, and 5033 had only COVID-19. Both at 30&nbsp;days and at any time, as compared to patients without, concomitant AS and COVID-19 subjects had a higher mortality rate (438.4 per 100 py, 95% CI 296.2-648.8, and 72.9, 95% CI 53.7-99.0, respectively) and a higher death risk (adjusted HR 5.5, 95% CI 3.7-8.2; and 2.8, 95% CI 2.1-3.9). AS patients presented increased mortality HR both in the presence and absence of COVID-19 at 30&nbsp;days (1.6, 95% CI 1.1-2.4; and 1.6, 95% CI 1.2-2.2, respectively) and at any time (1.6, 95% CI 1.1-2.1; 1.4, 95% CI 1.2-1.7, respectively). Conclusions and implications: AS was a significant mortality risk factor, independent of concomitant COVID-19. Careful AS management should always be pursued, even in acute and post-acute phases of COVID-19

Myocardial fibrosis and steatosis in patients with aortic stenosis: roles of myostatin and ceramides

Aortic stenosis (AS) involves progressive valve obstruction and a remodeling response of the left ventriculum (LV) with systolic and diastolic dysfunction. The roles of interstitial fibrosis and myocardial steatosis in LV dysfunction in AS have not been completely characterized. We enrolled 31 patients (19 women and 12 men) with severe AS undergoing elective aortic valve replacement. The subjects were clinically evaluated, and transthoracic echocardiography was performed pre-surgery. LV septal biopsies were obtained to assess fibrosis and apoptosis and fat deposition in myocytes (perilipin 5 (PLIN5)), or in the form of adipocytes within the heart (perilipin 1 (PLIN1)), the presence of ceramides and myostatin were assessed via immunohistochemistry. After BMI adjustment, we found a positive association between fibrosis and apoptotic cardiomyocytes, as well as fibrosis and the area covered by PLIN5. Apoptosis and PLIN5 were also significantly interrelated. LV fibrosis increased with a higher medium gradient (MG) and peak gradient (PG). Ceramides and myostatin levels were higher in patients within the higher MG and PG tertiles. In the linear regression analysis, increased fibrosis correlated with increased apoptosis and myostatin, independent from confounding factors. After adjustment for age and BMI, we found a positive relationship between PLIN5 and E/A and a negative correlation between septal S', global longitudinal strain (GLS), and fibrosis. Myostatin was inversely correlated with GLS and ejection fraction. Fibrosis and myocardial steatosis altogether contribute to ventricular dysfunction in severe AS. The association of myostatin and fibrosis with systolic dysfunction, as well as between myocardial steatosis and diastolic dysfunction, highlights potential therapeutic targets

Magnetic Resonance Imaging Confirmed Olfactory Bulb Reduction in Long COVID-19: Literature Review and Case Series

An altered sense of smell and taste was recognized as one of the most characteristic symptoms of coronavirus infection disease (COVID-19). Despite most patients experiencing a complete functional resolution, there is a 21.3% prevalence of persistent alteration at 12 months after infection. To date, magnetic resonance imaging (MRI) findings in these patients have been variable and not clearly defined. We aimed to clarify radiological alterations of olfactory pathways in patients with long COVID-19 characterized by olfactory dysfunction. A comprehensive review of the English literature was performed by analyzing relevant papers about this topic. A case series was presented: all patients underwent complete otorhinolaryngology evaluation including the Sniffin’ Sticks battery test. A previous diagnosis of SARS-CoV-2 infection was confirmed by positive swabs. The MRIs were acquired using a 3.0T MR scanner with a standardized protocol for olfactory tract analysis. Images were first analysed by a dedicated neuroradiologist and subsequently reviewed and compared with the previous available MRIs. The review of the literature retrieved 25 studies; most cases of olfactory dysfunction more than 3 months after SARS-CoV-2 infection showed olfactory bulb (OB) reduction. Patients in the personal case series had asymmetry and a reduction in the volume of the OB. This evidence was strengthened by the comparison with a previous MRI, where the OBs were normal. The results preliminarily confirmed OB reduction in cases of long COVID-19 with an altered sense of smell. Further studies are needed to clarify the epidemiology, pathophysiology and prognosis

Brown and Beige Adipose Tissue and Aging

Across aging, adipose tissue (AT) changes its quantity and distribution: AT becomes dysfunctional with an increase in production of inflammatory peptides, a decline of those with anti-inflammatory activity and infiltration of macrophages. Adipose organ dysfunction may lead to age-related metabolic alterations. Aging is characterized by an increase in adiposity and a decline in brown adipose tissue (BAT) depots and activity, and UCP1 expression. There are many possible links to age-associated involution of BAT, including the loss of mitochondrial function, impairment of the sympathetic nervous system, age-induced alteration of brown adipogenic stem/progenitor cell function and changes in endocrine signals. Aging is also associated with a reduction in beige adipocyte formation. Beige adipocytes are known to differentiate from a sub-population of progenitors resident in white adipose tissue (WAT); a defective ability of progenitor cells to proliferate and differentiate has been hypothesized with aging. The loss of beige adipocytes with age may be caused by changes in trophic factors in the adipose tissue microenvironment, which regulate progenitor cell proliferation and differentiation. This review focuses on possible mechanisms involved in the reduction of BAT and beige activity with aging, along with possible targets for age-related metabolic disease therapy