1,720,959 research outputs found
Classification of EEG and fNIRS signals from Completely Locked-in State Patients for a Brain-Computer Interface communication system
Full text linkPeople suffering from complete motor paralysis with no severe deficiency in cognitive abilities, syndrome called Completely Locked in State (CLIS), remain aware of their surroundings without being able to interact and communicate in any way. In this context, the only possibility of communicating is by the techniques of Brain-Computer Interface. In this work, the focus is on the features extraction and selection on EEG and fNIRS signals and, finally, on the combination of the two to develop a system capable of classifying affirmative and negative answers from users in CLIS. The analysis considers the data collected in 4 visits to one patient. The choice to focus on a single case was made because the psychophysical considerations on the state of the patient are fundamental interpreting the results and the author of this work had the opportunity to participate directly in some acquisition. Offline analysis led to good results in the classification of fNIRS signals. Once again, using EEG signals it was not possible to successfully classify yes/no answers. Finally, the combination of EEG and fNIRS features did not improve the performance of the system.ope
Classification of EEG and fNIRS signals from Completely Locked-in State Patients for a Brain-Computer Interface communication system
Full text linkPeople suffering from complete motor paralysis with no severe deficiency in cognitive abilities, syndrome called Completely Locked in State (CLIS), remain aware of their surroundings without being able to interact and communicate in any way. In this context, the only possibility of communicating is by the techniques of Brain-Computer Interface. In this work, the focus is on the features extraction and selection on EEG and fNIRS signals and, finally, on the combination of the two to develop a system capable of classifying affirmative and negative answers from users in CLIS. The analysis considers the data collected in 4 visits to one patient. The choice to focus on a single case was made because the psychophysical considerations on the state of the patient are fundamental interpreting the results and the author of this work had the opportunity to participate directly in some acquisition. Offline analysis led to good results in the classification of fNIRS signals. Once again, using EEG signals it was not possible to successfully classify yes/no answers. Finally, the combination of EEG and fNIRS features did not improve the performance of the system
A Sensorized Insole to Estimate Ground Reaction Forces and Center of Pressure During Gait
Full text linkTraditional methods for gait analysis require stationary equipment, leading to limitations in mobility and real-world applicability. Wearable devices, particularly sensorized insoles, offer a promising solution for gait analysis during sports and dynamic activities. This study presents the development and evaluation of a custom-made sensorized insole for accurate estimation of Ground Reaction Force (GRF) and Center of Pressure (CoP) during human gait. The insole integrates pressure sensors and an accelerometer, coupled with Long Short-Term Memory (LSTM) models, to capture temporal dynamics in gait patterns. Data from eleven healthy adult volunteers were collected, pre-processed, and used for model training and validation. Results demonstrate the effectiveness of the sensorized insole, with improvements in prediction accuracy when combining pressure and acceleration data. The addition of accelerometer data to pressure data led to a reduction in the Normalized Root Mean Square Error (NRMSE) for the medio-lateral component of GRF from 18.4% to 16.7%. While challenges remain, particularly in modeling medio-lateral components of GRF, the study provides insights into potential future directions for optimizing sensorized insoles and improving model performance
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
Population coding strategies in human tactile afferents
Full text linkSensory information is conveyed by populations of neurons, and coding strategies cannot always be deduced when considering individual neurons. Moreover, information coding depends on the number of neurons available and on the composition of the population when multiple classes with different response properties are available. Here, we study population coding in human tactile afferents by employing a recently developed simulator of mechanoreceptor firing activity. First, we highlight the interplay of afferents within each class. We demonstrate that the optimal afferent density to convey maximal information depends on both the tactile feature under consideration and the afferent class. Second, we find that information is spread across different classes for all tactile features and that each class encodes both redundant and complementary information with respect to the other afferent classes. Specifically, combining information from multiple afferent classes improves information transmission and is often more efficient than increasing the density of afferents from the same class. Finally, we examine the importance of temporal and spatial contributions, respectively, to the joint spatiotemporal code. On average, destroying temporal information is more destructive than removing spatial information, but the importance of either depends on the stimulus feature analysed. Overall, our results suggest that both optimal afferent innervation densities and the composition of the population depend in complex ways on the tactile features in question, potentially accounting for the variety in which tactile peripheral populations are assembled in different regions across the body
Mechanotransduction and information coding in the human peripheral tactile system
Full text linkThe human peripheral tactile system is responsible for the initial processing of tactile stimuli and is composed of the skin and various embedded mechanoreceptors innervated by afferents. Spiking models are widely used to characterize this system and infer how populations of afferents shape tactile perception. Leveraging existing models of tactile afferents and moved by their limitations, we present three studies designed to advance these essential tools in the investigation of the human peripheral tactile system.
Firstly, reconciling existing evidence, we quantitatively characterize the population of peripheral tactile afferents. We estimate that approximately 230,000 afferents cover the human body, provide innervation densities in different skin areas, and show the relation of these numbers with tactile acuity, hair follicle density, and somatosensory cortical representation.
Secondly, we ask how tactile afferents work together to encode information in complex ways. We find that information is spread across classes, and combining information from multiple classes improves transmission. We test the importance of temporal and spatial resolution in the population code, probing that destroying temporal information is more destructive than removing spatial information.
Finally, we use Optical Coherence Tomography to image the skin subsurface in vivo and dynamically and quantify the deformation of individual fingerprint ridges down to the type-1 mechanoreceptors' location. When scanning the skin with a flat surface, the ridge deforms as a single unit. Higher strains emerge from the stick-to-slip transition compared to plate movement reversal. When scanning the skin with small features, different ridge sub-units experience different strain patterns. Higher strains occur in the deepest layer imaged.
Overall, this research provides a better understanding of coding strategies of tactile afferents on a population level and of the link between skin mechanics and transduction mechanisms underlying tactile perception. Our findings will have implications for developing novel spiking models of the human peripheral tactile 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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