491 research outputs found

    On the Singular Spectrum of the Radiation Operator for Multiple and Extended Observation Domains

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    The problem of studying how spatial diversity impacts on the spectrum (singular values) of the radiation operator is addressed. This topic is of great importance because of its connection with the so-called number of degrees of freedom concept which in turn is a key parameter in inverse source problems as well as to the problem of transmitting information by waves from a source domain to an observation domain. The case of a bounded rectilinear source with the radiated field observed over multiple bounded rectilinear domains parallel to the source is considered. Then, the analysis is generalized to two-dimensional extended observation domains. Analytical arguments are developed to estimate the pertinent singular value behavior. This allows highlighting the way observation domain features affect spectrum behavior. Numerical examples are shown to support the analytical results

    Methods and Sensors for Slip Detection in Robotics: A Survey

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    The perception of slip is one of the distinctive abilities of human tactile sensing. The sense of touch allows recognizing a wide set of properties of a grasped object, such as shape, weight and dimension. Based on such properties, the applied force can be accordingly regulated avoiding slip of the grasped object. Despite the great importance of tactile sensing for humans, mechatronic hands (robotic manipulators, prosthetic hands etc.) are rarely endowed with tactile feedback. The necessity to grasp objects relying on robust slip prevention algorithms is not yet corresponded in existing artificial manipulators, which are relegated to structured environments then. Numerous approaches regarding the problem of slip detection and correction have been developed especially in the last decade, resorting to a number of sensor typologies. However, no impact on the industrial market has been achieved. This paper reviews the sensors and methods so far proposed for slip prevention in artificial tactile perception, starting from more classical techniques until the latest solutions tested on robotic systems. The strengths and weaknesses of each described technique are discussed, also in relation to the sensing technologies employed. The result is a summary exploring the whole state of art and providing a perspective towards the future research directions in the sector

    Progression of Lactobacillus plantarum prosthetic valve endocarditis followed by transesophageal echocardiogram

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    Endocarditis due to Lactobacillus species is extremely rare. We report an uncommon case of Lactobacillus plantarum bioprosthetic aortic valve endocarditis, presenting with severe aortic steno-regurgitation, which responded to conventional medical and surgical treatment. This case provides a better understanding of the disease process of L. plantarum and highlights the role of transesophageal echocardiography in following the entire course of endocarditis

    Multilevel control of an anthropomorphic prosthetic hand for grasp and slip prevention

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    The success of grasping and manipulation tasks of commercial prosthetic hands is mainly related to amputee visual feedback since they are not provided either with tactile sensors or with sophisticated control. As a consequence, slippage and object falls often occur. This article wants to address the specific issue of enhancing grasping and manipulation capabilities of existing prosthetic hands, by changing the control strategy. For this purpose, it proposes a multilevel control based on two distinct levels consisting of (1) a policy search learning algorithm combined with central pattern generators in the higher level and (2) a parallel force/position control managing slippage events in the lower level. The control has been tested on an anthropomorphic robotic hand with prosthetic features (the IH2 hand) equipped with force sensors. Bi-digital and tri-digital grasping tasks with and without slip information have been carried out. The KUKA-LWR has been employed to perturb the grasp stability inducing controlled slip events. The acquired data demonstrate that the proposed control has the potential to adapt to changes in the environment and guarantees grasp stability, by avoiding object fall thanks to prompt slippage event detection

    Indoor Localization System Based on Bluetooth Low Energy for Museum Applications

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    In the last few years, indoor localization has attracted researchers and commercial developers. Indeed, the availability of systems, techniques and algorithms for localization allows the improvement of existing communication applications and services by adding position information. Some examples can be found in the managing of people and/or robots for internal logistics in very large warehouses (e.g., Amazon warehouses, etc.). In this paper, we study and develop a system allowing the accurate indoor localization of people visiting a museum or any other cultural institution. We assume visitors are equipped with a Bluetooth Low Energy (BLE) device (commonly found in modern smartphones or in a small chipset), periodically transmitting packets, which are received by geolocalized BLE receivers inside the museum area. Collected packets are provided to the locator server to estimate the positions of the visitors inside the museum. The position estimation is based on a feed-forward neural network trained by a measurement campaign in the considered environment and on a non-linear least square algorithm. We also provide a strategy for deploying the BLE receivers in a given area. The performance results obtained from measurements show an achievable position estimate accuracy below 1 m

    Double Heterozygous Mutations Involving Both HNF1A/MODY3 and HNF4A/MODY1 Genes: A case report

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    none9Abstract We describe the first MODY case with mutations involving both HNF4A and HNF1A genes. History and Examination. A male patient was diagnosed with diabetes at age 17; the metabolic control rapidly worsened to insulin requirement. At that time no relatives were known to be affected by diabetes, which was diagnosed years later in both parents (father at age 50, mother at age 54) and the sister (age 32 during pregnancy). Investigations. The genetic screening showed a double heterozygosity for the mutation p.E508K in HNF1A/MODY3 gene and the novel variant p.R80Q in HNF4A/MODY1 gene. The genetic testing of the family showed that the father carried the MODY3 mutation while the mother, the sister and her two children carried the MODY1 mutation. Conclusions. MODY1 and MODY3 mutations may interact by chance to give a more severe form of diabetes (younger age at presentation, early need of insulin therapy to control hyperglycemia).mixedG. Forlani; S. Zucchini; A. Di Rocco; R. Di Luzio; M. Scipione; E. Marasco; G. Romeo; G. Marchesini Reggiani; V. MantovaniG. Forlani; S. Zucchini; A. Di Rocco; R. Di Luzio; M. Scipione; E. Marasco; G. Romeo; G. Marchesini Reggiani; V. Mantovan

    The Effect of Bergamot-Derived Polyphenolic Fraction on LDL Small Dense Particles and Non Alcoholic Fatty Liver Disease in Patients with Metabolic Syndrome

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    The occurrence of Metabolic Syndrome (MS) represents an independent risk factor for developing cardiovascular disease states in patients suffering from type 2 diabetes mellitus. Moreover, both the size of LDL particles and liver dysfunction identified as non alcoholic fatty liver disease (NAFLD) represent important biomarkers for the development of cardiometabolic risk in patients with MS. Here we studied the effect of bergamot polyphenolic fraction (BPF) in patients with MS and NAFLD. 107 patients were enrolled at the San Raffaele IRCCS (Rome). All of them showed ultrasonografic evidences of NAFLD and at least three out of five previous identified criteria for the diagnosis of MS. Patients were divided into two groups: one receiving placebo and the second receiving BPF 650 mg twice a day for 120 consecutive days. In the group receiving BPF 650 mg twice a day, a significant reduction of fasting plasma glucose, serum LDL cholesterol and triglycerides alongside with an increase of HDL cholesterol was found. This effect was accompanied by significant reduction of both ultrasonographic and metabolic biomarkers of NAFLD. Moreover, a significant reduction of small dense LDL particles, as detected via proton NMR Spectroscopy, was found after BPF treatment. In conclusion, our data confirm the beneficial effect of bergamot-extract in patients with MS an effect highlighted by significant reduction of small dense LDL particles and by improvement of NAFLD biomarkers. This suggests a potential preventive role of bergamot derivatives in reducing cardiometabolic risk
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