1,721,146 research outputs found
CT-Compatible Medical Drilling Stylet
No full textThis paper describes the design of a compact, lightweight CT-compatible, drill-press that is designed to be used in either a hand-held or stand-alone mode to assist with percutaneous bone based interventions. Previous medical drilling tools that have been developed have a metal structure and typically have one actuator for advancing the drill (feed) and another for rotating it (speed). After defining the device functional requirements and specifications, a deterministic design process was followed to generate several design concepts that were then evaluated based on their ability to satisfy the functional requirements. A final concept that uses a custom screw-spline to achieve helical motion of a shaft that is attached to a standard orthopedic drill was selected for prototyping. The design uses a single actuator to drive both the screw and spline nuts through two different gear ratios, resulting in a fixed ratio between the feed and speed. Apart from the motor which is placed away from the central drill axis, the device is largely made from plastic materials. A custom experimental setup was developed that enabled drilling into bone inside a CT scanner to be examined. Results showed that the device was successfully able to penetrate thick cortical bone and that its structure did not appreciably distort the medical images. Keywords: medical robotics, computed tomography, X-ray, drill, interventional radiology, bon
Preliminary evaluation of robotic needle distal tip repositioning
No full textAdvances in medical imaging now provide detailed images of solid tumors inside the body and miniaturized energy delivery systems enable tumor destruction through local heating powered by a thin electrode. We have developed a robot for accurately repositioning the distal tip of a medical instrument such an ablation probe to adjacent points within tissue. The position accuracy in ballistics gelatin was evaluated in a 2D experimental setup with a digital SLR camera that was fixed to a rig that also contained the gelatin. The robot was mounted to the rig in such a way that the stylet was deployed in a plane parallel the camera's lens. A grid paper attached to the back of the box containing the gelatin provided a stationary reference point for each of the pictures taken and also served as a coordinate system for making measurements. The measurement repeatability error was found by taking a stylet tip position measurement five times for two different pictures and found to be 0.26 mm. For a stylet with a radius of curvature of 31.5 mm and a diameter of 0.838 mm, the targeting accuracy was found to be 2.5 ± 1.4 mm at points that were approximately 38 mm lateral from the cannula axis
Air Efficient Soft Wearable Robot for High-Torque Elbow Flexion Assistance
No full text: Recent developments in soft wearable robots have shown promise for assistive and rehabilitative use-cases. For inflatable approaches, a major challenge in developing portable systems is finding a balance between portability, performance, and usability. In this paper, we present a textile-based robotic sleeve that can provide functional elbow flexion assistance and is compatible with a portable actuation unit (PAU). Flexion is driven by a curved textile actuator with internal pneumatic supports (IPS). We show that the addition of IPS improves torque generation and increases battery-powered actuations by 60%. We demonstrate that the device can provide enough torque throughout the ROM of the elbow joint for daily life assistance. Specifically, the device generates 13.5 Nm of torque at 90°. Experimental testing in five healthy individuals and two individuals with Amyotrophic Lateral Sclerosis (ALS) demonstrates its impact on wearer muscle activity and kinematics. The results with healthy subjects show that the device was able to reduce the bicep muscle activity by an average of 49.1±13.3% during static and dynamic exercises, 43.6±11.1% during simulated ADLs, and provided an assisted ROM of 134°±13°. Both ALS participants reported a reduced rate of perceived exertion during both static and dynamic tasks while wearing the device and had an average ROM of 115°±8°. Future work will explore other applications of the IPS and extend the approach to assisting multiple joints
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Assessment of full life-cycle air emissions of alternative shipping fuels
Full text linkThere is a need for alternative fuels in the shipping sector for two main motivations: to deliver a reduction in local pollutants and comply with existing regulation; and to mitigate climate change and cut greenhouse gas emissions. However, any alternative fuel must meet a range of criteria to become a viable option. Key among them is the requirement that it can deliver emissions reductions over its full life-cycle. For a set of fuels, comprising both conventional and alternative fuels, together with associated production pathways, this paper presents a life-cycle assessment with respect to six emissions species: local pollutants sulphur oxides, nitrogen oxides, and particulate matter; and greenhouse gases carbon dioxide, methane, and nitrous oxide. While the analysis demonstrates that no widely available fuel exists currently to deliver on both motivations, some alternative fuel options have the potential, if key barriers can be overcome. Hydrogen or other synthetic fuels rely on decarbonisation of both energy input to production and other feedstock materials to deliver reductions in greenhouse gas emissions. Similarly, bio-derived fuels can be an abatement option, but only if it can be ensured that land-use change whilst growing biomass does not impact wider potential savings and the sector is able to compete sufficiently for their use. These examples show that crucial barriers are located upstream in the respective fuel life-cycle and that the way to overcome them may reside beyond the scope of the shipping sector alone
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