Control Protocols for Range-Based Navigation of a Networked Group of Underwater Vehicles.

This paper tackles the problem of formation reconstruction for a team of vehicles based on the knowledge of the range between agents of a subset of the participants. One main peculiarity of the proposed approach is that the relative velocity between agents, which is a fundamental data to solve the problem, is not assumed to be known in advance neither directly communicated. For the purpose of estimating this quantity, a collaborative control protocol is designed in order to mount the velocity data in the motion of each vehicle as a parameter through a dedicated control protocol, so that it can be inferred from the motion of the neighbor agents. Moreover, some suitable geometrical constraints related to the agents' relative positions are built and explicitly taken into account in the estimation framework providing a more accurate estimate. The issue of the presence of delays in the transmitted signals is also studied and two possible solutions are provided explaining how it is possible to get a reasonable range data exchange to get the solution both in a centralized fashion and in a decentralized one. Numerical examples are presented corroborating the validity of the proposed approach.

Risk factors for silent myocardial ischemia in patients with well-controlled essential hypertension.

Silent myocardial ischemia (SMI) is frequently observed in patients with essential hypertension (EH). The major risk factor for SMI is uncontrolled blood pressure (BP), but SMI is also observed in patients with well-controlled BP. To evaluate the prevalence of SMI and the factors associated with SMI in EH patients with well-controlled BP. The medical records of 859 EH patients who underwent simultaneous 24-h ambulatory blood pressure monitoring (ABPM) and 24-h ambulatory electrocardiogram recording (AECG) were retrospectively evaluated. Each SMI episode was characterized by: (a) ST segment depression ≥0.5 mm; (b) duration of ST segment depression >60 s; and (c) reversibility of the ST segment depression. Overall 126 EH patients (14.7 %) had at least one episode of SMI. The SMI events were more frequent among patients with poorly controlled compared to those with well-controlled BP [86/479 (17.95 %) vs. 40/380 (10.52 %), p < 0.01]. Among EH patients with well-controlled BP, current and past smoking as well as the presence of an additional metabolic syndrome (MetS) constitutive element (obesity, impaired fasting glucose level or dyslipidemia) were significantly associated with the occurrence of SMI. In all EH patients with well-controlled BP and AECG evidence of SMI, there were one or more coronary artery stenotic lesions greater than 50 % found at coronary angiography. In EH patients who are current smokers, or have one or more additional components of a MetS there is markedly reduced benefit associated with good BP control with regard to the occurrence of myocardial ischemia: in this patient category, an AECG may help detect this condition.

Vitamin D and cardiometabolic disorders.

Recent clinical and experimental studies suggest that vitamin D status could play a significant role in the pathogenesis of cardiometabolic disorders as well as in their clinical severity. In particular, low vitamin D levels appear to increase the risk of major cardiovascular events in apparently healthy individuals and to worsen the prognosis quoad vitam and quoad valetudinem following a cardiovascular event. The relevance of these observations is amplified by the high prevalence of vitamin D deficiency and insufficiency that affect over one billion individuals at all ages worldwide. Randomized controlled trials are currently underway in U.S., Europe and Oceania to demonstrate a cause-effect relationship by assessing the effects of vitamin D supplementation on various cardiovascular outcomes. Aim of this review is to point out the more recent advances in knowledge about the relationship between vitamin D status and the incidence, prevalence and pathogenesis of more common cardiometabolic disorders.

Not smoking is associated with lower risk of hypertension: results of the Olivetti Heart Study.

BACKGROUND: Few epidemiological investigations evaluated the role of smoking cessation on blood pressure (BP), and the results are not univocal. Therefore, the aim of this study was to assess the effect of smoking cessation on the risk to develop hypertension (HPT) and on BP values. METHODS: This longitudinal study, with a follow-up period of 8 years, included the participants of the Olivetti Heart Study. Participants were 430 untreated normotensive non-diabetic men with normal renal function, examined twice in 1994-95 and in 2002-04. The sample included current smokers (S, n = 212), former smokers (ES, n = 145) and never smokers (NS, n = 73) at baseline. RESULTS: Basal body mass index (BMI), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were significantly higher in ES than in S (ES vs. S; BMI: 27.0 ± 2.5 vs. 26.1 ± 2.9 kg/m2; P < 0.01; SBP/DBP: 121.2 ± 9.3/80.0 ± 5.8 vs. 19.1 ± 9.9/77.4 ± 6.7 mm Hg; P < 0.05; M ± SD). After 8 years of follow-up, BP changes (Δ) were significantly lower in ES than in S (ΔSBP/DBP: 12.6 ± 13.4/7.9 ± 8.1 vs. 16.0 ± 14.9/10.3 ± 10.1 mm Hg; P < 0.05; M ± SD), also after adjustment for potential confounders. Moreover, at the last examination, the overall HPT prevalence was 33%, with lower values in ES than in S (25 vs. 38%, P = 0.01). After accounting for age, BP and BMI at baseline, and changes in smoking habit over the 8-year period, ES still had significant lower risk of HPT than S (odds ratio 0.30, 95% confidence interval 0.15-0.58; P < 0.01). CONCLUSIONS: In this sample of healthy men, smoking cessation was associated with lower BP increment and minor HPT risk, independently of potential confounders.

Nonsymmetric myocardial contribution to supranormal right ventricular function in the athlete's heart: combined assessment by speckle tracking and real time three-dimensional echocardiography.

PURPOSE: To investigate determinants of right ventricular (RV) function in competitive athletes by a combined assessment of speckle tracking (STE) and real time 3D echocardiography (RT3DE). METHODS: Right ventricular function of 40 top-level rowers was compared to 43 sedentary normal controls by standard Doppler echocardiography, RT3DE, and STE. RV diameters and wall thickness, tricuspid annular plane systolic excursion (TAPSE), tricuspid E/A ratio, and pulsed tissue Doppler of lateral tricuspid annulus were analyzed. RV volumes, ejection fraction (EF), and stroke volume (SV) were determined. RV global longitudinal strain (GLS) (average of 6 regions), septal strain (average of 3 septal regions, septal longitudinal strain [SLS]), and lateral strain (average of 3 lateral regions, lateral longitudinal strain [LLS]) were estimated by STE. RESULTS: The 2 groups were comparable for age, body mass index, and blood pressure, but heart rate was lower in rowers. RV diameters were larger and TAPSE, tricuspid E/A ratio, and tissue Doppler-derived s' and e' velocities were higher in rowers. By RT3DE, RV end-diastolic volume (EDV) and end-systolic volume were greater in rowers (both P < 0.0001), without difference in EF. GLS (P < 0.005) and LLS (P < 0.001), but not SLS, were greater in rowers. In pooled groups, LLS was related to EDV and SV, even after adjusting for heart rate, body mass index, and RV wall thickness by separate multiple linear regression analyses (ß coefficient = 0.247, P < 0.01 and ß = 0.225, P < 0.02, respectively). CONCLUSIONS: Right ventricular preload exerts its maximal influence on the longitudinal lateral fibers, which is independent on potential confounders and largely induces RV supranormal function in the athlete's heart.

The changing profile of patients with calcium nephrolithiasis and the ascendancy of overweight and obesity: a comparison of two patient series observed 25 years apart.

BACKGROUND: Epidemiological data indicate an increasing incidence and prevalence of nephrolithiasis (NL) worldwide in the last few decades. METHODS: The aim of this study was to compare the clinical and biochemical profiles of recurrent stone formers referred to a Kidney Stone Centre from March 1983 to June 1986 with the one featured by patients seen 25 years later in the same geographical area, Campania, southern Italy. RESULTS: Idiopathic calcium stone formers made up the large majority of the patient population in both series. Those examined in 2008-11 showed higher age at the onset of NL, higher prevalence of overweight/obesity and higher urinary excretion of oxalate and phosphate compared with those seen in 1983-86. The differences in the urinary biochemical variables remained significant upon accounting for age, gender, creatinine clearance and body mass index (BMI), and were not observed in patients with primary hyperparathyroidism enrolled in the same periods. A greater prevalence of uric acid stone formers was also observed in the 2008-11 population. CONCLUSIONS: The massive epidemics of overweight/obesity and the substantial modifications of dietary habits over the last few decades in most Western countries may be the factors underlying the changing clinical and biochemical profiles of patients with recurrent NL.

The role of echocardiography in the management of the sources of embolism.

The echocardiographic diagnosis of cardiac thrombi, vegetations and tumors as well as the identification of predisposing conditions such as patent foramen ovale, aortic atherosclerosis and other minor causes (e.g., mitral valve prolapse, mitral and aortic valve calcification) have crucial clinical relevance, affecting the choice of surgery and/or of pharmaceutical therapy in the setting of patients presenting embolism. The echocardiographic assessment helps not only for the retrospective diagnosis of sources of embolism but also for the prevention of events in asymptomatic patients. Echocardiography can also distinguish normal variants and artifacts from cardiac masses and tumors. Echocardiographic characterization/typology of cardiac sources of embolism is currently below par when compared with cardiac MRI, the current gold standard. Nevertheless, echocardiography remains the 'first-line' imaging tool, because of its low cost and the possibility to add easily available, functional and structural information at the patient's bedside.