236 research outputs found
Wind tunnel investigation on a squared–back commercial vehicle
Get PDFThe assessment of an appropriate methodology for a wind tunnel investigation on a square back vehicle model is presented and discussed. The CD−Re curve is evaluated in order
to identify the adequate range of Reynolds number for the tests. The drag coefficient value is attested at CD = 0.465 which is in accordance with the literature results for the same category of
vehicles considered. The repeatability and the accuracy of the CD have been analyzed through a campaign of measurements and an error propagation analysis is dedicated to associate the
correct uncertainty to the drag coefficient values. The analysis of statistical convergence of the measured quantities is also carried out in order to fix the adequate acquisition time. The
results of the experimental investigation regarding the measurement methodology, drag coefficient, base pressure distribution, position of the center of pressure, and wake measurements
are presented highlighting the main natural flow features. Moreover, the pressure fluctuations measured by microphone sensors allowed to evidence the unsteadiness and possible flow configurations involving the entire rear part
Wake control of a 3D bluff body
Get PDFBluff bodies are characterized by massive flow separation responsible of most of the pressure drag.
Three main contributions roughly determine the total amount of the body drag : 30% is due to the rolling tire, 45% derive from the rear base and 25% comes from the underbody flow and interferences. In the case of large and medium size trucks employed for short and long distance of transportations the fuel consumption can be considerable reduced through the control of the flow separation from the base. The afterbody geometry plays a key role for the drag contributions as showed by Ahmed [1]. Aider et al. [2] used passive vortex generators while piezoelectric vortex generators were investigated by Orazi et al. [3]. Continuous blowing slots as done by Rouméas et al. [4] have been also used on a semi-infinite body. The present investigation considers a simplified 3D car with square-back rear shape. The wake control consist in the injection of continuous jets through four rectangular slots mounted around the perimeter of the rear part. Furthermore, four curved slots are disposed near the wheel to control the flow separation in this region. The flow analysis is performed by means of CFD commercial code (STAR CCM+® by Cd-Adapco). Results of this preliminary investigation will be presented. The effects of the independent rear slots orientation (i) and of the jet velocity (Vi) are analyzed as well as the effects of the jets around the wheels. The study will be also carry out on a physical model that will be tested in a wind tunnel. In figure 1 the expanded model and a portion of the longitudinal section of the rear part of the body are shown
Functional Role of miR-155 in the Pathogenesis of Diabetes Mellitus and Its Complications
Get PDFSubstantial evidence indicates that microRNA-155 (miR-155) plays a crucial role in the pathogenesis of diabetes mellitus (DM) and its complications. A number of clinical studies reported low serum levels of miR-155 in patients with type 2 diabetes (T2D). Preclinical studies revealed that miR-155 partakes in the phenotypic switch of cells within the islets of Langerhans under metabolic stress. Moreover, miR-155 was shown to regulate insulin sensitivity in liver, adipose tissue, and skeletal muscle. Dysregulation of miR-155 expression was also shown to predict the development of nephropathy, neuropathy, and retinopathy in DM. Here, we systematically describe the reports investigating the role of miR-155 in DM and its complications. We also discuss the recent results from in vivo and in vitro models of type 1 diabetes (T1D) and T2D, discussing the differences between clinical and preclinical studies and shedding light on the molecular pathways mediated by miR-155 in different tissues affected by DM
Trapped vortex cell for aeronautical applications: flow analysis through PIV and Wavelet transform tools.
Get PDFAbstract Results of the application of a trapped vortex cell to an airfoil with the aim of improving the
aerodynamic performances are presented for two complementary experiments arranged at CIRA and at
Politecnico di Torino. In the CIRA experiments, PIV measurements on a simplified configuration were carried
out to characterize the trapped vortical structure and its effect on the separating flow downstream of the cell. In
the experimental investigation at Politecnico di Torino, static pressure distributions were measured around a
complete airfoil model, to yield lift and pitching moment coefficients. Wake surveys were also carried out to
measure the drag. To study the unsteady phenomena inside the cavity pressure fluctuations signals were also
investigated using Kulite sensors. In both experiments, the angle of attack of the airfoil and the Reynolds number
were varied. It is shown that the flow inside the cell is highly unsteady with significant shedding of flow
structures downstream. This phenomenon results in a large region of separated flow, in higher drag and lower
lift. By contrast, the cell flow is considerably stabilized and regularized by applying distributed suction over the
cell wall. As a result, the flow downstream of the cell reattaches and lower drag and larger lift are observed
Alcohol-related behaviour in freshmen university students in Sardinia, Italy
Get PDFThis study aims to provide a picture of University of Cagliari students’ alcohol-related behaviour and to explore factors associated with it. Data were collected by administering a questionnaire to 992 freshmen university students from different programs consisting of twelve closed questions, including three questions from the Alcohol Use Disorders Identification Test for Consumption (AUDIT-C short form). Three subgroups of alcohol-related behaviour were distinguished (risky drinkers, social drinkers and abstainers). In order to explore factors associated with patterns of alcohol consumption, a multivariate logistic regression was performed. The prevalence of risky drinkers was 35%. A binge-drinking behaviour at least once in the last twelve months was declared by 65% (more widespread in men and in students living away from their parents). Risky consumption is significantly associated with age of onset of alcohol use, living away from parents’ home, drinking outside meals and attending health courses. Regarding the levels of daily alcohol consumption perceived as a health risk, 66% of men and 88% of women indicate values higher than those recommended. The results underline the need for tailored prevention measures. University could be a promising setting to implement actions according to a health promotion perspective, to empower students to control their alcohol consumption
Order out of chaos: Sense of coherence and the mediating role of coping resources in explaining mental health during COVID-19 in 7 countries
Get PDFIn the midst of the COVID-19 pandemic and the universal chaos created by it, this study explores the role of sense of coherence (Soc, Antonovsky, 1979) and how it enables coping with a stressful situation and staying well. SOC is a generalized orientation which allows one to perceive the world as comprehensible, manageable, and meaningful. In an attempt to understand 'how does the SOC work' we employed the salutogenic assumption that a strong SOC allows one to reach out in any given situation and find those resources appropriate to the specific stressor. Thus, we hypothesized that the positive impact of SOC on mental health outcomes would be mediated through coping resources that are particularly salient in times of crisis. One resource is related to the micro level (perceived family support) and the other concerns the macro level (trust in leaders and social-political institutions). Data collection was conducted in different countries during May-June 2020 via online platforms. The data included 7 samples of adult participants (age 18-90) from Israel (n = 669), Italy (n = 899), Spain (n = 476), Germany (n = 708), Austria (n = 1026), Switzerland (n = 147), and the U.S. (n = 506). The questionnaires included standard tools (MHC-SF, SOC-13) as well as questionnaires of perceived family support and trust that were adapted to the pandemic context. As expected, SOC was associated with mental health in all the samples. Perceived family support and trust in leaders and social-political institutions mediated the relationships between SOC and mental health, controlling for age, gender, and level of financial risk. It appears that SOC has a universal meaning, not limited by cultural and situational characteristics. The discussion focuses on the theoretical, social, and political applications of the salutogenic model - and its core concept of SOC - in the context of coping with a global pandemic across different cultural contexts and countries
Vaccination attitude and communication in early settings: An exploratory study
Get PDFBackground: This study assesses attitudes towards vaccination in mothers of new-born babies and explores its association with different exposures to communication. Methods: Data were collected through questionnaires administered by means of interviews. Results: Data highlighted that 20% of mothers showed an orientation towards vaccine hesitancy. As for the reasons behind the attitude to vaccine hesitancy, data showed that concern is a common feature. As for the different exposures to communication, 49% of mothers did not remember having received or looked for any information about vaccination during pregnancy and post-partum; 25% stated they received information from several healthcare and non-healthcare sources; 26% declared having received or looked for information by means of healthcare and non-healthcare sources, as well as having taken part in a specific meeting during antenatal classes or at birth centres. The attitude towards vaccine hesitancy tends to reduce as exposure to different communication increases. Conclusions: This study supports the hypothesis that participation in interactive meetings in small groups focused on vaccination during the prenatal course or at the birth point may act as an enabling factor contributing to a decrease in the tendency to experience vaccine hesitation
Preoperative assessment of cardiovascular risk in patients undergoing noncardiac surgery: The Orion study
Get PDFIn patients undergoing noncardiac surgery risk indices can estimate patients' perioperative risk of major cardiovascular complications. The indexes currently in use were derived from observational studies that are now outdated with respect to the current clinical context. We undertook a prospective, observational, cohort study to derive, validate, and compare a new risk index with established risk indices. We evaluated 7335 patients (mean age 63±13 years) who underwent noncardiac surgery. Based on prospective data analysis of 4600 patients (derivation cohort) we developed an Updated Cardiac Risk Score (UCRS), and validated the risk score on 2735 patients (validation cohort). Four variables (i.e. the UCRS) were significantly associated with the risk of a major perioperative cardiovascular events: high-risk surgery, preoperative estimate glomerular filtration rate <30 ml/min/1.73 m2, age ≥75 years, and history of heart failure. Based on the UCRS we created risk classes 1,2,3 and 4 and their corresponding 30-day risk of a major cardiovascular complication was 0.8% (95% confidence interval [CI] 0.5-1.7), 2.5 (95% CI 1.6-5.6), 8.7 (95% CI 5.2-18.9) and 27.2 (95% CI 11.8-50.3), respectively. No significant differences were found between the derivation and validation cohorts. Receiver operating characteristic (ROC) curves demonstrate a high predictive performance of the new index, with greater power to discriminate between the various classes of risk than the indexes currently used. The high predictive performance and simplicity of the UCRS make it suitable for wide-scale use in preoperative cardiac risk assessment of patients undergoing noncardiac surgery
Sodium/glucose cotransporter 2 (SGLT2) inhibitors improve cardiac function by reducing JunD expression in human diabetic hearts
Get PDFBackground: The pathogenesis of experimental diabetic cardiomyopathy may involve the activator protein 1 (AP-1) member, JunD. Using non-diabetic heart transplant (HTX) in recipients with diabetes, we examined the effects of the diabetic milieu (hyperglycemia and insulin resistance) on cardiac JunD expression over 12 months. Because sodium/glucose cotransporter-2 inhibitors (SGLT2i) significantly reverse high glucose-induced AP-1 binding in the proximal tubular cell, we investigated JunD expression in a subgroup of type 2 diabetic recipients receiving SGLT2i treatment. Methods: We evaluated 77 first HTX recipients (40 and 37 patients with and without diabetes, respectively). Among the recipients with diabetes, 17 (45.9%) were receiving SGLT2i treatment. HTX recipients underwent standard clinical evaluation (metabolic status, echocardiography, coronary computed tomography angiography, and endomyocardial biopsy). In the biopsy samples, we evaluated JunD, insulin receptor substrates 1 and 2 (IRS1 and IRS2), peroxisome proliferator-activated receptor-γ (PPAR-γ), and ceramide levels using real-time polymerase chain reaction and immunofluorescence. The biopsy evaluations in this study were performed at 1–4 weeks (basal), 5–12 weeks (intermediate), and up to 48 weeks (final, end of 12-month follow-up) after HTX. Results: There was a significant early and progressive increase in the cardiac expression of JunD/PPAR-γ and ceramide levels, along with a significant decrease in IRS1 and IRS2 in recipients with diabetes but not in those without diabetes. These molecular changes were blunted in patients with diabetes receiving SGLT2i treatment. Conclusion: Early pathogenesis in human diabetic cardiomyopathy is associated with JunD/PPAR-γ overexpression and lipid accumulation following HTX in recipients with diabetes. Remarkably, this phenomenon was reduced by concomitant therapy with SGLT2i, which acted directly on diabetic hearts
An Overview of the Cardiorenal Protective Mechanisms of SGLT2 Inhibitors
Get PDFSodium-glucose co-transporter 2 (SGLT2) inhibitors block glucose reabsorption in the renal proximal tubule, an insulin-independent mechanism that plays a critical role in glycemic regulation in diabetes. In addition to their glucose-lowering effects, SGLT2 inhibitors prevent both renal damage and the onset of chronic kidney disease and cardiovascular events, in particular heart failure with both reduced and preserved ejection fraction. These unexpected benefits prompted changes in treatment guidelines and scientific interest in the underlying mechanisms. Aside from the target effects of SGLT2 inhibition, a wide spectrum of beneficial actions is described for the kidney and the heart, even though the cardiac tissue does not express SGLT2 channels. Correction of cardiorenal risk factors, metabolic adjustments ameliorating myocardial substrate utilization, and optimization of ventricular loading conditions through effects on diuresis, natriuresis, and vascular function appear to be the main underlying mechanisms for the observed cardiorenal protection. Additional clinical advantages associated with using SGLT2 inhibitors are antifibrotic effects due to correction of inflammation and oxidative stress, modulation of mitochondrial function, and autophagy. Much research is required to understand the numerous and complex pathways involved in SGLT2 inhibition. This review summarizes the current known mechanisms of SGLT2-mediated cardiorenal protection
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