275 research outputs found

    Competing Quantum Orderings in Cuprate Superconductors: A Minimal Model

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    We present a minimal model for cuprate superconductors. At the unrestricted mean-field level, the model produces homogeneous superconductivity at large doping, striped superconductivity in the underdoped regime and various antiferromagnetic phases at low doping and for high temperatures. On the underdoped side, the superconductor is intrinsically inhomogeneous and global phase coherence is achieved through Josephson-like coupling of the superconducting stripes. The model is applied to calculate experimentally measurable ARPES spectra.Comment: 5 pages, 4 eps included figure

    Sensor-Based Task Ergonomics Feedback for a Passive Low-Back Exoskeleton

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    Low-back exoskeletons are a wide-spreading technology tackling low-back pain, the leading work-related musculoskeletal disorder in many work sectors. Currently, spring-based (i.e., passive) exoskeletons are the mostly adopted in the industry, being cheaper and generally less complex and more intuitive to use. We introduce a system of interconnected wireless sensing units to provide online ergonomics feedback to the wearer. We integrate the system into our passive low-back exoskeleton and evaluate its usability with healthy volunteers and potential end users. In this way, we provide the exoskeleton with a tool aimed both at monitoring the interaction of the system with the user, providing them with an ergonomics feedback during task execution. The sensor system can also be integrated with a custom-developed Unity3D application which can be used to interface with Augmented- or Virtual-Reality applications with higher potential for improved user feedback, ergonomics training, and offline ergonomics evaluation of the workplace. We believe that providing ergonomics feedback to exoskeleton users in the industrial sector could help further reduce the drastic impact of low-back pain and prevent its onset

    Composições de susbstratos e ambientes de enraizamento na estaquia de Ilex paraguariensis A. St.-Hil.

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    Devido à carência de informações a respeito da propagação vegetativa de erva-mate, conduziu-se um experimento com o objetivo de avaliar o ambiente de enraizamento e composições de substrato na sobrevivência, enraizamento e vigor de estacas de Ilex paraguariensis de plantas de 12 anos de idade. Testou-se o efeito de três clones (A32, A34 e A36), seis substratos (S1 - substrato para enraizamento à base de casca de pinus; S2 - substrato para enraizamento à base de casca de pinus e vermiculita; S3 - casca de arroz carbonizada + vermiculita fina + substrato para enraizamento à base de casca de pinus e vermiculita (1:1:1 v/v); S4 - casca de arroz carbonizada + substrato para enraizamento à base de casca de pinus e vermiculita (1:1 v/v); S5 - casca de arroz carbonizada + vermiculita fina (1:1 v/v); S6 - fibra de coco) e dois ambientes de enraizamento (casa de vegetação automatizada e simples). Embora não tenham ocorrido grandes variações entre os ambientes testados, o enraizamento das estacas mostrou-se baixo. O uso da mistura de casca de arroz carbonizada + substrato para enraizamento à base de casca de pinus e vermiculita na proporção 1:1 (v/v) é aconselhado para estaquia de erva-mate

    User-Centered Back-Support Exoskeleton: Design and Prototyping

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    Exhausting manual labor is still predominant in the industrial context. It typically consists in manipulating heavy parts or working in non-ergonomic conditions. The resulting work-related musculoskeletal disorders are a major problem to tackle. The most-affected body section is the the lumbar spine. Recently, exoskeletons have been identified as a possible non-invasive solution to reduce the impact of low-back pain. State-of-the-art prototypes have been optimized to: follow unconstrained human kinematics, (partially) relieve the load on assisted joints, and allow anthropometric adaptation. Yet, this technology still has limited adoption. Manufacturing optimization may address the following limitations: bulky/heavy resulting designs, complex assembly and maintenance, high manufacturing costs, long procedures for adaptation and wearing, and psychological effects (e.g., cognitive load and usability). In this contribution, the aforementioned issues are tackled improving a previous low-back exoskeleton prototype. In particular, kinematic analysis, Finite-Element-Method, and topological optimization have been combined to obtain a lightweight prototype, testing different materials (Nylon, carbon-fiber reinforced PC/ABS, etc.). We applied both Design for Assembly and Design for Manufacturability. The resulting exoskeleton prototype is described in the paper, ready for end-user field tests

    Three combinations of clonidine in association with tiletamine-zolazepam for anaesthesia induction in rats: evaluation of reflexes and pain sensibility

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    The aim of this study was to assess the combination of tiletamine-zolazepam (Zoletil 20\uae) with three different doses of clonidine for general anaesthesia induction in rats submitted to vascular microsurgery. The evaluation of anaesthetic and analgesic effects was performed in 30 Wistar rats randomly divided into three groups and induced with Zoletil 20 [90 mg/kg Intraperitoneal (IP)] associated with three different doses of clonidine (60\u201390\u2013120 \u3bcg/kg IP). Four clinical parameters were evaluated after induction: loss of righting reflex, voluntary movement, the pedal withdrawal response, and pain sensitivity tested by pinching the tail. The combination of Zoletil with 90 and 120 \u3bcg/kg of clonidine provided a surgical anaesthesia; however, 90 \u3bcg/kg of clonidine provided the most rapid anaesthesia induction, as confirmed by data obtained by clinical evaluation of the loss of the pedal withdrawal response and the absence of the tail pinch response. The increase in dose of clonidine did not lead to a more rapid action of the \u3b12 agonist, probably due to achievement of a dose-dependent plateau

    Anthropometric indices of sarcopenia in patients with Chronic Kidney Disease

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    The Chronic Kidney Disease (CKD) is a kidney dysfunction for which the estimated Glomerular Filtration Rate (eGFR) result
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