983 resultados para Razón real (ratio rei)
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Background International standard practice for the correct confirmation of the central venous access device is the chest X-ray. The intracavitary electrocardiogram-based insertion method is radiation-free, and allows real-time placement verification, providing immediate treatment and reduced requirement for post-procedural repositioning. Methods Relevant databases were searched for prospective randomised controlled trials (RCTs) or quasi RCTs that compared the effectiveness of electrocardiogram-guided catheter tip positioning with placement using surface-anatomy-guided insertion plus chest X-ray confirmation. The primary outcome was accurate catheter tip placement. Secondary outcomes included complications, patient satisfaction and costs. Results Five studies involving 729 participants were included. Electrocardiogram-guided insertion was more accurate than surface anatomy guided insertion (odds ratio: 8.3; 95% confidence interval (CI) 1.38; 50.07; p=0.02). There was a lack of reporting on complications, patient satisfaction and costs. Conclusion The evidence suggests that intracavitary electrocardiogram-based positioning is superior to surface-anatomy-guided positioning of central venous access devices, leading to significantly more successful placements. This technique could potentially remove the requirement for post-procedural chest X-ray, especially during peripherally inserted central catheter (PICC) line insertion.
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Piezoelectric ultrasound transducers are commonly used to convert mechanical energy to electrical energy and vice versa. The transducer performance is highly affected by the frequency at which it is excited. If excitation frequency and main resonant frequency match, transducers can deliver maximum power. However, the problem is that main resonant frequency changes in real time operation resulting in low power conversion. To achieve the maximum possible power conversion, the transducer should be excited at its resonant frequency estimated in real time. This paper proposes a method to first estimate the resonant frequency of the transducer and then tunes the excitation frequency accordingly in real time. The measurement showed a significant difference between the offline and real time resonant frequencies. Also, it was shown that the maximum power was achieved at the resonant frequency estimated in real time compare to the one measured offline.
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Hand-held ebook readers present many challenges for Australian libraries that want to integrate this emerging technology into their library’s service. In 2001, both Toowoomba City Library and the Brisbane City Council Library Service embarked on such projects. This paper reports on the differing experience of these two public library services, outlining difficulties encountered, customer reactions to the technology, and the central issues that acquiring and circulating these readers pose for public libraries in Australia.
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Engineering-based modeling activities provide a rich source of meaningful situations that capitalize on and extend students’ routine learning. By integrating such activities within existing curricula, students better appreciate how their school learning in mathematics and science applies to problems in the outside world...
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This study is an evaluation of design students’ perceptions of the benefits of collective learning in a real-world collaborative design studio. Third year students worked in inter-disciplinary teams representing architecture, interior design, landscape architecture, and industrial design. Responding to a real-world brief and in consultation with an industry partner client and early childhood education pre-service teachers, the teams were required to collectively propose a design response for a community-based child and family centre, on an iconic koala sanctuary site. Data were collected using several methods including a participatory action research method, through the form of a large analogue, collaborative jigsaw puzzle. Using a grounded theory methodology, qualitative data were thematically analysed to reveal six distinct aspects of collaboration, which positively impacted the students’ learning experience. The results of this study include recommendations for improving real world collaboration in the design studio in preparation for students’ transition into professional practice.
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The Bouncing Back research study, which began after the Queensland flooding in January 2011, has organically expanded through a number of architectural student design projects and exhibitions, which have sought to respond to catastrophic flooding events. In September 2011, 10 Queensland University of Technology architecture students travelled to Sydney to help construct a 1:1 true-to-life scale shelter, for the Emergency Shelter Exhibition at Customs House in Circular Quay. During the construction of the shelter, data were collected in situ, through dynamic interviews with the students. Using a grounded theory methodology, data were coded and then thematically analysed, to reveal three influential factors that positively impacted the students’ learning in this informal context. These were the student experience, the process of learning through physical making/fabrication, and development of empathy with the community. Analysis of these three factors demonstrated how this informal situated learning activity promoted vitally important learning in a real-world context, which is difficult to replicate in a physical on-campus environment.
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Changes to the redox status of biological systems have been implicated in the pathogenesis of a wide variety of disorders including cancer, Ischemia-reperfusion (I/R) injury and neurodegeneration. In times of metabolic stress e.g. ischaemia/reperfusion, reactive oxygen species (ROS) production overwhelms the intrinsic antioxidant capacity of the cell, damaging vital cellular components. The ability to quantify ROS changes in vivo, is therefore essential to understanding their biological role. Here we evaluate the suitability of a novel reversible profluorescent probe containing a redox-sensitive nitroxide moiety (methyl ester tetraethylrhodamine nitroxide, ME-TRN), as an in vivo, real-time reporter of retinal oxidative status. The reversible nature of the probe's response offers the unique advantage of being able to monitor redox changes in both oxidizing and reducing directions in real time. After intravitreal administration of the ME-TRN probe, we induced ROS production in rat retina using an established model of complete, acute retinal ischaemia followed by reperfusion. After restoration of blood flow, retinas were imaged using a Micron III rodent fundus fluorescence imaging system, to quantify the redox-response of the probe. Fluorescent intensity declined during the first 60 min of reperfusion. The ROS-induced change in probe fluorescence was ameliorated with the retinal antioxidant, lutein. Fluorescence intensity in non-Ischemia eyes did not change significantly. This new probe and imaging technology provide a reversible and real-time response to oxidative changes and may allow the in vivo testing of antioxidant therapies of potential benefit to a range of diseases linked to oxidative stress
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Purpose During in vitro chondrogenesis of human mesenchymal stem cells (hMSCs) hypertrophy is an inadvertent event associated with cell differentiation toward the osteogenic lineage. Up to now, there is no stringent experimental control mechanism to prevent hypertrophy of MSCs. Microgravity is known to have an impact on osteogenesis. In this study, the influence of simulated microgravity (SMG) on both chondrogenesis and hypertrophy of hMSCs was evaluated. Methods A bioreactor using a rotating wall vessel was constructed to simulate microgravity. Pellet cultures formed from hMSCs (P5) were supplemented with human transforming growth factor-β3 (TGF-β3). The hMSC pellet cultures treated with TGF-β3 were either kept in SMG or in a control system. After three weeks of culture, the chondrogenic differentiation status and level of hypertrophy were examined by safranin-O staining, immunohistochemistry and quantitative real-time PCR. Results SMG reduced the staining for safranin-O and collagen type II. The expression of collagen type X α1 chain (COL10A1) and collagen type II α1 chain (COL2A1) were both significantly reduced. There was a higher decrease in COL2A1 than in COL10A1 expression, resulting in a low COL2A1/COL10A1 ratio. Conclusions SMG reduced hypertrophy of hMSCs during chondrogenic differentiation. However, the expression of COL2A1 was likewise reduced. Even more, the COL2A1/COL10A1 ratio decreased under SMG conditions. We therefore assume that SMG has a significant impact on the chondrogenic differentiation of hMSCs. However, due to the high COL2A1 suppression under SMG, this culture system does not yet seem to be suitable for a potential application in cartilage repair.
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Background Cervical Spinal Manipulation (CSM) is considered a high-level skill of the central nervous system because it requires bimanual coordinated rhythmical movements therefore necessitating training to achieve proficiency. The objective of the present study was to investigate the effect of real-time feedback on the performance of CSM. Methods Six postgraduate physiotherapy students attending a training workshop on Cervical Spine Manipulation Technique (CSMT) using inertial sensor derived real-time feedback participated in this study. The key variables were pre-manipulative position, angular displacement of the thrust and angular velocity of the thrust. Differences between variables before and after training were investigated using t-tests. Results There were no significant differences after training for the pre-manipulative position (rotation p = 0.549; side bending p = 0.312) or for thrust displacement (rotation p = 0.247; side bending p = 0.314). Thrust angular velocity demonstrated a significant difference following training for rotation (pre-training mean (sd) 48.9°/s (35.1); post-training mean (sd) 96.9°/s (53.9); p = 0.027) but not for side bending (p = 0.521). Conclusion Real-time feedback using an inertial sensor may be valuable in the development of specific manipulative skill. Future studies investigating manipulation could consider a randomized controlled trial using inertial sensor real time feedback compared to traditional training.
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This paper presents the development and experimental validation of a prototype system for online estimation and compensation of wind disturbances onboard small Rotorcraft unmanned aerial systems (RUAS). The proposed approach consists of integrating a small pitot-static system onboard the vehicle and using simple but effective algorithms for estimating the wind speed in real time. The baseline flight controller has been augmented with a feed-forward term to compensate for these wind disturbances, thereby improving the flight performance of small RUAS in windy conditions. The paper also investigates the use of online airspeed measurements in a closed-loop for controlling the RUAS forward motion without the aid of a global positioning system (GPS). The results of more than 80 flights with a RUAS confirm the validity of our approach.
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Giant Cell Arteritis (GCA) is the most common vasculitis affecting the elderly. Archived formalin-fixed paraffin-embedded (FFPE) temporal artery biopsy (TAB) specimens potentially represent a valuable resource for large-scale genetic analysis of this disease. FFPE TAB samples were obtained from 12 patients with GCA. Extracted TAB DNA was assessed by real time PCR before restoration using the Illumina HD FFPE Restore Kit. Paired FFPE-blood samples were genotyped on the Illumina OmniExpress FFPE microarray. The FFPE samples that passed stringent quality control measures had a mean genotyping success of >97%. When compared with their matching peripheral blood DNA, the mean discordant heterozygote and homozygote single nucleotide polymorphisms calls were 0.0028 and 0.0003, respectively, which is within the accepted tolerance of reproducibility. This work demonstrates that it is possible to successfully obtain high-quality microarray-based genotypes FFPE TAB samples and that this data is similar to that obtained from peripheral blood.
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This thesis has investigated how to cluster a large number of faces within a multi-media corpus in the presence of large session variation. Quality metrics are used to select the best faces to represent a sequence of faces; and session variation modelling improves clustering performance in the presence of wide variations across videos. Findings from this thesis contribute to improving the performance of both face verification systems and the fully automated clustering of faces from a large video corpus.
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Recently, efficient scheduling algorithms based on Lagrangian relaxation have been proposed for scheduling parallel machine systems and job shops. In this article, we develop real-world extensions to these scheduling methods. In the first part of the paper, we consider the problem of scheduling single operation jobs on parallel identical machines and extend the methodology to handle multiple classes of jobs, taking into account setup times and setup costs, The proposed methodology uses Lagrangian relaxation and simulated annealing in a hybrid framework, In the second part of the paper, we consider a Lagrangian relaxation based method for scheduling job shops and extend it to obtain a scheduling methodology for a real-world flexible manufacturing system with centralized material handling.
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The new furnace at the Materials Characterization by X-ray Diffraction beamline at Elettra has been designed for powder diffraction measurements at high temperature (up to 1373 K at the present state). Around the measurement region the geometry of the radiative heating element assures a negligible temperature gradient along the capillary and can accommodate either powder samples in capillary or small flat samples. A double capillary holder allows flow-through of gas in the inner sample capillary while the outer one serves as the reaction chamber. The furnace is coupled to a translating curved imaging-plate detector, allowing the collection of diffraction patterns up to 2[theta] [asymptotically equal to] 130°.
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This paper presents real-time simulation models of electrical machines on FPGA platform. Implementation of the real-time numerical integration methods with digital logic elements is discussed. Several numerical integrations are presented. A real-time simulation of DC machine is carried out on this FPGA platform and important transient results are presented. These results are compared to simulation results obtained through a commercial off-line simulation software.