1,721,500 research outputs found
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
Use of a biocompatible fiducial marker in evaluating the accuracy of computed tomography image registration
No full textRATIONALE AND OBJECTIVES. Accurate registration of computed tomography (CI) images to the patient is crucial for computer-assisted surgery, Markers used in roentgen stereo-grammetric analysis (RSA) can be located in a CT scan using a novel approach and also can be located physically, Roentgen stereo-grammetric analysis data act as ''ground truth'' for the three-dimensional marker locations. METHODS. Two foam-bone phantoms were marked, The markers were scanned seven times with RSA, three times with axial CT, and contacted four times with a coordinate measuring arm, Root-mean-square (RMS) errors were derived for the registrations. RESULTS. Computed tomography and RSA data register to 0.15 mm RMS error, Computed tomography and arm data register to 0.25 mm, The markers are biocompatible, and the coordinate measuring arm is usable in an operating room. CONCLUSIONS. Typical in vitro registration errors are approximately 2 mm, The authors have developed a marker that provides superior registration, and a procedure that can be used for in vivo studies
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
Ion-substituted calcium phosphate coatings deposited by plasma-assisted techniques: A review
No full textOne of the main critical aspects behind the failure or success of an implant resides in its ability to fast bond with the surrounding bone. To boost osseointegration, the ideal implant material should exhibit composition and structure similar to those of biological apatite. To this aim, the most common approach is to coat the implant surface with a coating of hydroxyapatite (HA), resembling the main component of mineralized tissues. However, bone apatite is a non-stoichiometric, multi-substituted poorly-crystalline apatite, containing significant amounts of foreign ions, with high biological relevance. Ion-substituted HAs can be deposited by so called “wet methods”, which are however poorly reproducible and hardly industrially feasible; at the same time bioactive coatings realized by plasma assisted method, interesting for industrial applications, are generally made of stoichiometric (i.e. un-substituted) HA. In this work, the literature concerning plasma-assisted deposition methods used to deposit ion-substituted HA was reviewed and the last advances in this field discussed. The ions taken into exam are those present in mineralized tissues and possibly having biological relevance. Notably, literature about this topic is scarce, especially relating to in vivo animal and clinical trials; further on, available studies evaluate the performance of substituted coatings from different points of view (mechanical properties, bone growth, coating dissolution, etc.) which hinders a proper evaluation of the real efficacy of ion-doped HA in promoting bone regeneration, compared to stoichiometric HA. Moreover, results obtained for plasma sprayed coatings (which is the only method currently employed for deposition at the industrial scale) were collected and compared to those of novel plasma-assisted techniques, that are expected to overcome its limitations. Data so far available on the topic were discussed to highlight advantages, limitations and possible perspectives of these procedures
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
Hyperhomocysteinemia in patients with acute porphyrias: a possible effect of ALAS1 modulation by siRNAm therapy and its control by vitamin supplementation
No full textExperimental Characterization of the Flow Trough the Nozzle of a 2-Stroke Air Assisted Direct Injection System
No full textIn recent years, due to the adoption of more and more severe restrictions on internal combustion engines emissions, many efforts have been dedicated to the development of direct injection technology for spark ignition engines. In particular, for two-stroke engines, the adoption of DI systems is crucially important in order to reduce unburned fuel losses during the scavenging process.
In this frame, the University of Perugia and Piaggio & C. established a joint research program the analyse the behaviour of the Piaggio air-assisted DI system named FAST (Fully Atomised Stratified Turbulence), currently fitted on the M164 two-stroke 50 cc engine.
As a first step of this research activity, the present paper describes the results of the experimental characterisation of the steady flow obtained with the FAST system nozzle. The experimental analysis has been performed by means of a light sheet visualisation technique based on a Nd-Yag laser and a CCD camera. The off-line analysis of images pertinent to peculiar planes of the two phase flow allowed to determine its global structure at the nozzle outlet and the influences of various nozzle configurations on the flow pattern itself. Further, the influence of the combustion chamber shape and spark plug positions on the development of the two-phase flow has been investigated
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