1,720,989 research outputs found
DIFFERENTIAL PHOTOIONIZATION CROSS-SECTION CALCULATIONS FOR H2S USING THE RANDOM-PHASE-APPROXIMATION WITH L(2) BASIS FUNCTIONS
No full textThe photoionization cross sections and asymmetry parameters of the four main valence ionization processes in H2S, corresponding to the formation of respectively 2b1, 5a1, 2b2 and 4a1 holes, have been calculated in the random phase approximation (RPA). By resorting to a recently proposed computational procedure, based on the K-matrix technique, the RPA equations for the four coupled ionization channels have been projected on a basis set of L2 functions and solved, at any excitation energy above the ionization threshold, in a way that allows to recover the electronic continuum degeneracy
Electronic properties by Green's Function calculations. Renormalized optical potential results: Ne, Ar, HF, H2O, NH3
No full text
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
Vision-Based Dynamic Virtual Fixtures for Tools Collision Avoidance in Robotic Surgery
No full textIn robot-aided surgery, during the execution of typical bimanual procedures such as dissection, surgical tools can collide and create serious damage to the robot or tissues. The da Vinci robot is one of the most advanced and certainly the most widespread robotic system dedicated to minimally invasive surgery. Although the procedures performed by da Vinci-like surgical robots are teleoperated, potential collisions between surgical tools are a very sensitive issue declared by surgeons. Shared control techniques based on Virtual Fixtures (VF) can be an effective way to help the surgeon prevent tools collision. This letter presents a surgical tools collision avoidance method that uses Forbidden Region Virtual Fixtures. Tool clashing is avoided by rendering a repulsive force to the surgeon. To ensure the correct definition of the VF, a marker-less tool tracking method, using deep neural network architecture for tool segmentation, is adopted. The use of direct kinematics for tools collision avoidance is affected by tools position error introduced by robot component elasticity during tools interaction with the environment. On the other hand, kinematics information can help in case of occlusions of the camera. Therefore, this work proposes an Extended Kalman Filter (EKF) for pose estimation which ensures a more robust application of VF on the tool, coupling vision and kinematics information. The entire pipeline is tested in different tasks using the da Vinci Research Kit system
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
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