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Biologically Plausible Control of Fast Reaching Movements Using Non-Traditional Cost Functions
Get PDFOptimal control has been used as a technique to uncover mathematical principles which are observed regularly in the dynamics of human movement. We present two new models of human reaching movements. While both are rooted in optimal control theory, the models were conceived by questioning basic tenets and typical practices used in optimal control as applied to human movement. In the first model, we use cost functions that measure various control signals via the L_infinity norm as opposed to the commonly used L_2 norm. Doing so models human reaching movements as well as current approaches, but results in control signals that can be reasoned about in terms of neural spikes and their timing. In the second model, we change the organization of the terms within a single, multi-term cost function by transforming it into many single-term cost functions. This approach yields sub-optimal results with regard to cost, yet produces equal or better results when applied to accuracy in modeling human reaching movements. The traditional optimal control approach to modeling human movement assumes that humans have an optimal design in terms of the anatomy and physiology of their motor systems. This design is assumed to optimally minimize costs such as energy consumption, or error while attaining a goal. However, it is more likely that in changing environments/niches, humans and other animals are still evolving, and therefore have not yet arrived at an optimal design. By reorganizing the terms of a cost function in a cost-suboptimal way, while achieving high accuracy with regard to modeling the movements, we challenge the basic premise of cost-optimality that underlies optimal control based models of human movement. Additionally, this reorganization of cost function terms into multiple cost functions results in multiple, interacting control signals, making it possible to combine the these signals in ways that resemble the connectivity of the human motor system, which contains a diverse set of neural signals working in concert, each with its own character and purpose. For this reason, we introduce a framework that generalizes these concepts, which can be utilized for further modeling of human movement. The framework expands upon traditional optimal control as applied to modeling human movements by supporting multiple interacting control signals. This allows for experiments which more closely resemble the neural architecture of the motor system, thereby making it easier to reason about experimental results in terms of the construction of the human motor system
The Bugle : Vol. 88
No full textYearbook for Virginia Tech in Blacksburg, Virginia. The yearbook includes information about the school as well as photographs and illustrations of the student body, teachers, organizations, and buildings
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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