1,720,956 research outputs found
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
Clasificación de palabras no pronunciadas presentes en electroencefalogramas (EEG)
Get PDFThe present work aims to the development of a method for the processing and
classification of electroencephalographic signals (EEG), belonging of a single subject,
to recognize unspoken words belonging to a reduced vocabulary. Specifically,
a precise recognition would allow to mentally control a computer screen cursor,
thus, with this purpose, the vocabulary is composed by the Spanish language
words: “arriba”,“abajo”, “izquierda”, “derecha”, and “seleccionar”.
To start the process, the EEG signals were acquired using a protocol based
on markers, to know a priori in what part of the EEG signal a subject imagines
the pronunciation of an indicated word. With the markers were formed windows,
between which the samples could be found. To accomplish the objective, only the
signals from channels F7, FC5, T7 y P7 (which are the nearest to the Wernicke
and Broca areas) were taken in count. After that, the signals coming from those
channels were filtered using a band-pass FIR filter at 4-25 Hz., and the windows
were adjusted to 256 samples. Furthermore, features were obtained using discrete
wavelet transform (DWT) to train and assess four classifiers: Naive Bayes (NB),
Random Forests (RF), Support Vector Machines (SVM) and Bagging-RF. The
evaluation measures are accuracy and kappa index obtained using 10-folds cross
validation.
EEG signals belonging to 21 subjects were recorded, for each subject around
30 windows for each word were obtained. In the case of the best classifier, Bagging-
RF, the accuracy rate and kappa index average were 40.48% and 0.24, respectively. Furthermore, an analysis at the unspoken words level classification for Bagging-
RF and Random Forests was performed, where the classifiers were assessed with
recall, specificity, precision, and f-measure.
The results are still far of the precision needed to effectively control a BCI, but
they are encouraging because accuracy rates are above 20 %, i.e. above chance for
five classes, and kappa values are greater than 0, which are values comparable
to state of the art research. Based on them, it can be concluded that EEG signals
actually, contain information to allow the classification of the unspoken words
belonging to a reduced vocabulary by the proposed method. That is why, unspoken
speech turns out to be a promising and intuitive electrophysiologic source to
control BCIs.La presente investigación tiene como objetivo desarrollar un método de procesamiento
y clasificación de señales electroencefalográficas (EEG) de un individuo
para reconocer palabras no pronunciadas de un vocabulario reducido. Específicamente,
un reconocimiento preciso permitirá controlar mentalmente el cursor de
una computadora, ya que, con ese fin, el vocabulario consta de las palabras del
lenguaje español: “arriba”, “abajo”, “izquierda”, “derecha”, y “seleccionar”.
Para iniciar el proceso, las señales EEG se adquieren utilizando un protocolo
básico basado en marcadores, para saber a priori en qué parte de la señal la
persona imagina la dicción (habla no pronunciada) de la palabra indicada, con
los marcadores se forman ventanas. Para cumplir el objetivo, únicamente son de
interés las señales de los canales F7, FC5, T7 y P7 (los más cercanos a las áreas
cerebrales de Broca y Wernicke). Posteriormente, éstas son filtradas utilizando
un FIR pasa-bandas en el rango de 4-25 Hz, y las ventanas son ajustadas a 256
muestras. Además, se extraen características mediante la transformada wavelet
discreta que son utilizadas para entrenar y evaluar a cuatro clasificadores: Naive
Bayes (NB), Random Forests (RF), Máquina de vectores de soporte (SVM), y Bagging
de Random Forest (Bagging-RF). Las medidas de evaluación son la exactitud
y el coeficiente kappa obtenidas mediante validación cruzada con 10 pliegues.
Se grabaron señales EEG de 21 individuos, para cada uno de los cuales se tienen
alrededor de 30 ventanas correspondientes a cada una de las palabras. Para el caso
del mejor clasificador Bagging-RF, los valores promedio tanto del porcentaje de exactitud como para el coeficiente kappa son 40.48% y 0.24, respectivamente.
Además, se presenta un análisis de Bagging-RF y RF a nivel de la clasificación de
las palabras no pronunciadas, donde se evalúa a los clasificadores con el recuerdo,
la especificidad, la precisión y la medida-F.
Los resultados aún distan de lo necesario para controlar eficazmente a una
BCI sin embargo, debido a que los porcentajes de exactitud están arriba del 20 %,
es decir, arriba del azar para cinco clases, y los valores de kappa mayores a 0, se
puede concluir que las señales EEG efectivamente contienen información que hace
posible la clasificación de las palabras no pronunciadas del vocabulario reducido
mediante el método propuesto
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
Análisis y clasificación de electroencefalogramas (EEG) registrados durante el habla imaginada
Get PDFLa forma más sencilla de comunicarnos con otras personas es mediante el lenguaje
oral. Sin embargo, existen situaciones en las que no es posible emitir una señal acústica
entendible, o bien, se requiere comunicar un mensaje de forma privada o en ambientes
ruidosos. En estas situaciones son deseables sistemas, conocidos como interfaces de
habla silente (SSI del inglés Silent Speech Interfaces), que traten de aprovechar diferentes
tipos de habla registradas de diferentes órganos involucrados en la producción
del lenguaje hablado como: el tracto vocal, el rostro, la lengua, los dientes, la glotis e
inclusive el cerebro. Este último también ha sido de interés para el área de investigación
de las interfaces cerebro-computadora (BCI, por sus siglas en inglés), las cuales tienen
a la comunicación como uno de sus propósitos principales. Para tratar de lograr este
propósito, las BCI típicas registran la actividad cerebral mediante electroencefalogramas
(EEG), y se basan en 4 neuro-paradigmas (potenciales corticales lentos, imágenes
motoras, señales P300 y potenciales visuales evocados) que suelen ser poco intuitivos y
necesitan de una traducción al dominio del lenguaje. En consecuencia, la presente tesis
explora un neuro-paradigma alternativo llamado habla imaginada, el cual se refiere a
la pronunciación interna de palabras pero sin emitir sonidos ni articular gestos faciales
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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