1,720,996 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
A dynamic and probabilistic orienteering problem
No full textWe consider an online version of the orienteering problem, where stochastic service requests arise during a first time interval from customers located on the nodes of a graph. Every request must be accepted/rejected in real time. Later, a vehicle must visit the accepted customers during a second time interval. Each accepted request implies a prize, depending on the customer, and a service cost, depending on the routing decisions. Moreover, an accepted request implies a reduction of the routing time available for possible future requests. Each acceptance/rejection decision is made to maximize the expected profit, i.e., the difference between expected prices and expected service costs. We formulate the problem as a Markov Decision Process and derive analytical expressions for the transition probabilities and the optimal policy. Since an exact policy computation is intractable, we design and test several heuristic approaches, including static approximation, simple greedy (non-anticipatory) methods, Sample Average Approximation (SAA) of the objective function using Monte Carlo sampling of future events. We perform extensive computational tests on the proposed algorithms and discuss the pros and cons of the different methods
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
Endoscopic Third Ventriculostomy in Patients with Secondary Triventricular Hydrocephalus from a Haemorrhage or Ischaemia in the Posterior Cranial Fossa
No full textBackground: The aim of this project was to evaluate the efficacy of endoscopic third ventriculostomy (ETV) in the treatment of acute hydrocephalus caused by a haemorrhage or ischaemia in the posterior cranial fossa. Methods: 21 patients who had acute triventricular hydrocephalus resulting from ischaemia in 8 cases, and from cerebellar haemorrhage in 13 cases were treated with endoscopic third ventriculostomy. This series was compared with a control group of 30 patients, with clinical neuroradiological characteristics comparable to the preceding group (18 acute post-haemorrhage hydrocephalus and 12 post-ischaemia in the posterior cranial fossa), treated by external ventricular drainage (EVD). All patients were monitored clinically and by brain computed axial tomography (CT) to measure the dimensions of the lateral and third ventricles. The criteria used to define efficacy were based on the image of the postoperative cerebral CT scan. Results: No patient suffered haemorrhagic complications from surgical procedures or additional neurological deficits. There was no postoperative mortality or added morbidity. In all cases there was an improvement of intracranial hypertension. Clinical improvement was associated with a reduction of the ventricular dimensions documented by serial CT scans. Conclusions: We consider that, in selected cases, ETV can be suggested as the first choice treatment instead of the classic EVD. In the overall management of such patients, ETV has no or a very low rate of complications and allows shorter hospitalisation and earlier transfer to rehabilitative structures
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
Integrating ontological and linguistic knowledge for Conceptual Information Extraction
No full textText understanding makes strong assumptions about the conceptualisation of the underlying knowledge domain. This mediates between the accomplishment of the specific task at the one hand and the knowledge expressed in the target text fragments at the other. However, building domain conceptualisations from scratch is a very complex and time-consuming task. Traditionally, the reuse of available domain resources, although not constituting always the best, has been applied as an accurate and cost effective solution. Here, we investigate the possibility of exploiting sources of domain knowledge (e.g. a subject reference system) to build a linguistically motivated domain concept hierarchy. The limitation connected with the use of domain taxonomies as ontological resources will be firstly discussed in the specific light of IE, i.e. for supporting linguistic inference. We then define a method for integrating the taxonomical domain knowledge and a general-purpose lexical knowledge base, like WordNet. A case study, i.e. the integration of the MeSH, Medical Subject Headings, and WordNet, will be then presented as a proof of the effectiveness and accuracy of the overall approach
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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