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This work presents the first experimental characterization of the flow field in the vicinity of periodically spaced discrete roughness elements (DRE) in a swept wing boundary layer. The time-averaged velocity fields are acquired in a volumetric domain by high-resolution dual-pulse tomographic particle tracking velocimetry. Investigation of the stationary flow topology indicates that the near-element flow region is dominated by high- and low-speed streaks. The boundary layer spectral content is inferred by spatial fast Fourier transform (FFT) analysis of the spanwise velocity signal, characterizing the chordwise behaviour of individual disturbance modes. The two signature features of transient growth, namely algebraic growth and exponential decay, are identified in the chordwise evolution of the disturbance energy associated with higher harmonics of the primary stationary mode. A transient decay process is instead identified in the near-wake region just aft of each DRE, similar to the wake relaxation effect previously observed in two-dimensional boundary layer flows. The transient decay regime is found to condition the onset and initial amplitude of modal crossflow instabilities. Within the critical DRE amplitude range (i.e. affecting boundary layer transition without causing flow tripping) the transient disturbances are strongly receptive to the spanwise spacing and diameter of the elements, which drive the modal energy distribution within the spatial spectra. In the super-critical amplitude forcing (i.e. causing flow tripping) the near-element stationary flow topology is dominated by the development of a high-speed and strongly fluctuating region closely aligned with the DRE wake. Therefore, elevated shears and unsteady disturbances affect the near-element flow development. Combined with the harmonic modes transient growth these instabilities initiate a laminar streak structure breakdown and a bypass transition process. [ABSTRACT FROM AUTHOR]

The effect of discrete roughness elements on the development and breakdown of stationary crossflow instability on a swept wing is explored. Receptivity to various element heights and chordwise locations is explored using a combination of experimental and theoretical tools. Forcing configurations, determined based on linear stability predictions, are manufactured and applied on the wing in a low turbulence facility. Measurements are performed using infrared thermography, quantifying the transition front location, and planar particle image velocimetry, providing a reconstruction of stationary crossflow instabilities and their associated growth. Measurements are corroborated with simulations based on nonlinear parabolised stability equations. Results confirm the efficacy of discrete roughness elements in introducing and conditioning stationary crossflow instabilities. Primary instability amplitudes and resulting laminar-turbulent transition location are found to strongly depend on both roughness amplitude and chordwise location. The Reynolds number based on element height is found to satisfactorily approximate the initial forcing amplitude, revealing the importance of local velocity effects in non-zero-pressure gradient flows. Direct estimation of initial perturbation amplitudes from nonlinear simulations suggests the existence of pertinent flow mechanisms in the element vicinity, active in conditioning the onset of modal instabilities. Dedicated velocimetry planes, elucidate the development of a momentum deficit wake which rapidly decays downstream of the element followed by mild growth, representing the first experimental evidence of transient behaviour in swept wing boundary layers. The outcome of this work identifies a strong scalability of the transition dynamics to roughness amplitude and location, warranting the upscaling of roughness elements to more accessible, measurable and spatially resolved configurations in future experiments. [ABSTRACT FROM AUTHOR]

Background: To estimate the prevalence of respiratory symptoms in individuals with type 2 diabetes, as compared to the general population.Methods: Between 2007 and 2010 the screening questionnaire of GEIRD (Gene Environment Interactions in Respiratory Diseases) study was administered to two samples of Verona general population, aged respectively 45-64 years and 65-84 years, and to a convenience sample of individuals with type 2 diabetes, consequently recruited at the local Diabetes Centre. Ninety-four and 165 people with type 2 diabetes, aged respectively 45-64 and 65-84 years, were compared with 676 and 591 subjects in the same age range from the general population. The influence of type 2 diabetes on respiratory symptoms was evaluated by logistic regression models, controlling for sex, age (45-54, 55-64, 65-74, 75-84 years), education level, smoking habits and heavy vehicle traffic exposure and adjusting standard errors of ORs for intra-sample correlation.Results: Compared to the general population, dyspnoea limiting walking pace on level ground (grade 2 dyspnoea) was more frequently reported by people with type 2 diabetes, irrespective of age (p < 0.001), while self-reported chronic cough/phlegm was more common in those aged 45-64 years (p = 0.02). These results were confirmed by multivariable analysis: compared to their counterparts from the general population, people with type 2 diabetes aged 45-54 years showed an increased risk of reporting grade 2 dyspnoea (OR = 3.92, 95% CI 3.28-4.68) or chronic cough/phlegm (OR = 1.69, 1.60-1.78). Similar figures held significant at older ages (75-84 years), although partially blunted (dyspnoea: OR = 1.79, 1.68-1.91; chough/phlegm: OR = 1.09, 1.03-1.16). As such, the interaction between age class and type 2 diabetes was significant for both respiratory disorders. The proportion of self-reported dyspnoea among individuals with type 2 diabetes significantly increased across incremental body-mass index (BMI), from 15.4 to 25.4% and further to 41.3% respectively in normoweight, overweight and obese patients (p = 0.048).Conclusions: People with type 2 diabetes more frequently reported grade 2 dyspnoea and chronic cough/phlegm than the general population of the same age, although presenting similar smoking habits. Diabetes appears to anticipate the lung ageing process, recorded in the general population. The increased occurrence of dyspnoea at incremental BMI among individuals with type 2 diabetes may reflect both cardiovascular and respiratory impairment in this high-risk patient population. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the rate and determinants of concordance between advanced diabetic retinopathy (DR) and chronic kidney disease (CKD), as assessed by both albuminuria and estimated glomerular filtration rate (eGFR), in the large cohort of the Renal Insufficiency And Cardiovascular Events (RIACE) Italian multicenter study.Research Design and Methods: Patients with type 2 diabetes (n = 15,773) visiting consecutively 19 hospital-based diabetes clinics in years 2007 and 2008 were examined. DR was assessed by dilated fundoscopy. CKD was defined based on albuminuria and eGFR.Results: CKD was present in 58.64% of subjects with advanced DR, whereas advanced DR was detectable only in 15.28% of individuals with any CKD and correlated with the albuminuric CKD phenotypes more than with the nonalbuminuric phenotype. Age, male sex, diabetes duration, hemoglobin A(1c), hypertension, triglycerides, previous cardiovascular disease, and, inversely, HDL-cholesterol correlated independently with the presence of any CKD in individuals with advanced DR; correlates differed according to the presence of albuminuria, reduced eGFR, or both. Conversely, factors associated with the presence of advanced DR in subjects with any CKD were diabetes treatment, previous cardiovascular disease, albuminuria, and, inversely, smoking, eGFR, and age at diagnosis.Conclusions: Concordance of CKD with advanced DR is low in subjects with type 2 diabetes, and CKD without advanced DR is more frequent than isolated advanced DR, at variance with type 1 diabetes. Factors independently associated with the presence of any CKD in individuals with advanced DR differ, at least in part, from those correlating with the presence of advanced DR in subjects with any CKD and by CKD phenotype. [ABSTRACT FROM AUTHOR]

Objective: To assess differences between the effects of aerobic and resistance training on HbA(1c) (primary outcome) and several metabolic risk factors in subjects with type 2 diabetes, and to identify predictors of exercise-induced metabolic improvement.Research Design and Methods: Type 2 diabetic patients (n = 40) were randomly assigned to aerobic training or resistance training. Before and after 4 months of intervention, metabolic phenotypes (including HbA(1c), glucose clamp-measured insulin sensitivity, and oral glucose tolerance test-assessed β-cell function), body composition by dual-energy X-ray absorptiometry, visceral (VAT) and subcutaneous (SAT) adipose tissue by magnetic resonance imaging, cardiorespiratory fitness, and muscular strength were measured.Results: After training, increase in peak oxygen consumption (V(O(2peak))) was greater in the aerobic group (time-by-group interaction P = 0.045), whereas increase in strength was greater in the resistance group (time-by-group interaction P < 0.0001). HbA(1c) was similarly reduced in both groups (-0.40% [95% CI -0.61 to -0.18] vs. -0.35% [-0.59 to -0.10], respectively). Total and truncal fat, VAT, and SAT were also similarly reduced in both groups, whereas insulin sensitivity and lean limb mass were similarly increased. β-Cell function showed no significant changes. In multivariate analyses, improvement in HbA(1c) after training was independently predicted by baseline HbA(1c) and by changes in V(O(2peak)) and truncal fat.Conclusions: Resistance training, similarly to aerobic training, improves metabolic features and insulin sensitivity and reduces abdominal fat in type 2 diabetic patients. Changes after training in V(O(2peak)) and truncal fat may be primary determinants of exercise-induced metabolic improvement. [ABSTRACT FROM AUTHOR]

Objective: Data on cardiac function in patients with nonalcoholic fatty liver disease (NAFLD) are limited and conflicting. We assessed whether NAFLD is associated with abnormalities in cardiac function in patients with type 2 diabetes.Research Design and Methods: We studied 50 consecutive type 2 diabetic individuals without a history of ischemic heart disease, hepatic diseases, or excessive alcohol consumption, in whom NAFLD was diagnosed by ultrasonography. A tissue Doppler echocardiography with myocardial strain measurement was performed in all patients.Results: Thirty-two patients (64%) had NAFLD, and when compared with the other 18 patients, age, sex, BMI, waist circumference, hypertension, smoking, diabetes duration, microvascular complication status, and medication use were not significantly different. In addition, the left ventricular (LV) mass and volumes, ejection fraction, systemic vascular resistance, arterial elasticity, and compliance were also not different. NAFLD patients had lower e' (8.2 ± 1.5 vs. 9.9 ± 1.9 cm/s, P < 0.005) tissue velocity, higher E-to-e' ratio (7.90 ± 1.3 vs. 5.59 ± 1.1, P < 0.0001), a higher time constant of isovolumic relaxation (43.1 ± 10.1 vs. 33.2 ± 12.9 ms, P < 0.01), higher LV-end diastolic pressure (EDP) (16.5 ± 1.1 vs. 15.1 ± 1.0 mmHg, P < 0.0001), and higher LV EDP/end diastolic volume (0.20 ± 0.03 vs. 0.18 ± 0.02 mmHg, P < 0.05) than those without steatosis. Among the measurements of LV global longitudinal strain and strain rate, those with NAFLD also had higher E/global longitudinal diastolic strain rate during the early phase of diastole (E/SR(E)). All of these differences remained significant after adjustment for hypertension and other cardiometabolic risk factors.Conclusions: Our data show that in patients with type 2 diabetes and NAFLD, even if the LV morphology and systolic function are preserved, early features of LV diastolic dysfunction may be detected. [ABSTRACT FROM AUTHOR]

Objective: Recent studies have suggested an association between hyperuricemia and adverse renal outcomes in nondiabetic populations. Data on the relationship between hyperuricemia and the risk of incident chronic kidney disease (CKD) in type 2 diabetic patients with normal or near-normal kidney function are lacking. We determined whether baseline serum uric acid levels predict the subsequent development of CKD in patients with type 2 diabetes.Research Design and Methods: We followed 1,449 type 2 diabetic patients with normal kidney function and without overt proteinuria for 5 years for the occurrence of incident CKD (defined as overt proteinuria or estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m(2)).Results: During a 5-year follow-up period, 194 (13.4%) patients developed incident CKD. The cumulative incidence of CKD was significantly greater in patients with hyperuricemia than in those without hyperuricemia (29.5 vs. 11.4%, P < 0.001). In univariate logistic regression analysis, the presence of hyperuricemia roughly doubled the risk of developing CKD (odds ratio [OR] 2.55 [95% CI 1.71-3.85], P < 0.001). After adjusting for age, sex, BMI, smoking status, diabetes duration, systolic blood pressure, antihypertensive treatment, insulin therapy, HbA(1c), eGFR, and albuminuria, hyperuricemia was associated with an increased risk of incident CKD (adjusted OR 2.10 [1.16-3.76], P < 0.01). In continuous analyses, a 1-SD increment in the serum uric acid level was significantly associated with a 21% increased risk of CKD.Conclusions: In type 2 diabetic individuals with preserved kidney function, hyperuricemia seems to be an independent risk factor for the development of incident CKD. [ABSTRACT FROM AUTHOR]