1,720,965 research outputs found
Modelling and identification of characteristic kinematic features preceding freezing of gait with convolutional neural networks and layer-wise relevance propagation
No full textBACKGROUND: Although deep neural networks (DNNs) are showing state of the art performance in clinical gait analysis, they are considered to be black-box algorithms. In other words, there is a lack of direct understanding of a DNN's ability to identify relevant features, hindering clinical acceptance. Interpretability methods have been developed to ameliorate this concern by providing a way to explain DNN predictions. METHODS: This paper proposes the use of an interpretability method to explain DNN decisions for classifying the movement that precedes freezing of gait (FOG), one of the most debilitating symptoms of Parkinson's disease (PD). The proposed two-stage pipeline consists of (1) a convolutional neural network (CNN) to model the reduction of movement present before a FOG episode, and (2) layer-wise relevance propagation (LRP) to visualize the underlying features that the CNN perceives as important to model the pathology. The CNN was trained with the sagittal plane kinematics from a motion capture dataset of fourteen PD patients with FOG. The robustness of the model predictions and learned features was further assessed on fourteen PD patients without FOG and fourteen age-matched healthy controls. RESULTS: The CNN proved highly accurate in modelling the movement that precedes FOG, with 86.8% of the strides being correctly identified. However, the CNN model was unable to model the movement for one of the seven patients that froze during the protocol. The LRP interpretability case study shows that (1) the kinematic features perceived as most relevant by the CNN are the reduced peak knee flexion and the fixed ankle dorsiflexion during the swing phase, (2) very little relevance for FOG is observed in the PD patients without FOG and the healthy control subjects, and (3) the poor predictive performance of one subject is attributed to the patient's unique and severely flexed gait signature. CONCLUSIONS: The proposed pipeline can aid clinicians in explaining DNN decisions in clinical gait analysis and aid machine learning practitioners in assessing the generalization of their models by ensuring that the predictions are based on meaningful kinematic features.status: Publishe
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
A data-driven approach for detecting gait events during turning in people with Parkinson's disease and freezing of gait
No full textBackground:
Manual annotation of initial contact (IC) and end contact (EC) is a time consuming process. There are currently no robust techniques available to automate this process for Parkinson's disease (PD) patients with freezing of gait (FOG).
Objective:
To determine the validity of a data-driven approach for automated gait event detection.
Methods:
15 freezers were asked to complete several straight-line and 360 degree turning trials in a 3D gait laboratory during the off-period of their medication cycle. Trials that contained a freezing episode were indicated as freezing trials (FOG) and trials without a freezing episode were termed as functional gait (FG). Furthermore, the highly varied gait data between onset and termination of a FOG episode was excluded. A Temporal Convolutional Neural network (TCN) was trained end-to-end with lower extremity kinematics. A Bland-Altman analysis was performed to evaluate the agreement between the results of the proposed model and the manual annotations.
Results:
For FOG-trials, F1 scores of 0.995 and 0.992 were obtained for IC and EC, respectively. For FG-trials, F1 scores of 0.997 and 0.999 were obtained for IC and EC, respectively. The Bland-Altman plots indicated excellent timing agreement, with on average 39% and 47% of the model predictions occurring within 10 ms from the manual annotations for FOG-trials and FG-trials, respectively.
Significance:
These results indicate that our data-driven approach for detecting gait events in PD patients with FOG is sufficiently accurate and reliable for clinical applications.sponsorship: KU Leuvenstatus: Published onlin
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
Detection of Lint by Using Machine Vision
Full text linkThis thesis, commissioned by Häme University of Applied Sciences, researches the possibility of detecting lint by using machine vision. Due to the small particle size and high movement speed of the lint, various issues occur. Firstly, to detect the small lint particles a sufficient resolution is required. Secondly, since the lint has a high movement speed a high framerate is required to fully represent all the lint passing by. Lastly, a short exposure time is required to prevent inaccuracy due to motion blur. The goals of this thesis are to research the most optimal machine vision components, if the hardware currently available can detect the small particles with a sufficient framerate and a method to prevent motion blur.
The most optimal components were found by performing a literature study. Calculations were made to test if the currently available hardware can fulfil the goals. A colleague created a short duration strobe light to prevent motion blur. Lastly, a practical test setup and MATLAB program were created to verify the theoretical conclusions and detect the lint.
The strobe light uses four high power white LEDs with a flash duration of one microsecond. The calculations have concluded that the currently available hardware is capable of fully representing the lint passing by at a minimum particle size of 45 microns. Analyses of the MATLAB program verified that the theoretical calculations were correct.Deze thesis, uitgevaardigd door Häme University of Applied Sciences, onderzoekt de mogelijkheid tot het detecteren van stofdeeltjes door gebruik te maken van machine visie. Door de kleine dimensies en hoge voortbewegingssnelheden van de deeltjes treden er allerlei problemen op. Zo is een hoge resolutie noodzakelijk om de deeltjes te detecteren. Ook moet de framerate van de camera voldoende snel zijn om alle deeltjes die voorbij bewegen te detecteren. Ten laatste, is een korte sluitertijd van de sensor noodzakelijk om motion blur te voorkomen. Het doel van deze thesis is om de meest optimale machine visie onderdelen te onderzoeken, de mogelijkheid om het lint te detecteren met de hardware die beschikbaar is te onderzoeken en om een oplossing te zoeken voor motion blur.
De meest optimale machine visie setup werd gevonden met een literatuurstudie. Berekeningen zijn gemaakt om de beschikbare hardware te testen. Een flits van zeer korte duur is door een collega student gemaakt om motion blur te voorkomen. Ten laatste, is er een praktische opstelling en een MATLAB-programma gemaakt om de theoretische conclusies te verifiëren en het stof te detecteren.
De flits gebruikt vier hoogvermogen witte leds met een flitsduur van één microseconde. De berekeningen toonden aan dat de beschikbare hardware in staat is om alle deeltjes te filmen met een minimum grote van 45 micrometer. Het Matlab programma verifieerde dat de theoretische berekeningen correct waren
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
Detection of Lint by Using Machine Vision
No full textThis thesis, commissioned by Häme University of Applied Sciences, researches the possibility of detecting lint by using machine vision. Due to the small particle size and high movement speed of the lint, various issues occur. Firstly, to detect the small lint particles a sufficient resolution is required. Secondly, since the lint has a high movement speed a high framerate is required to fully represent all the lint passing by. Lastly, a short exposure time is required to prevent inaccuracy due to motion blur. The goals of this thesis are to research the most optimal machine vision components, if the hardware currently available can detect the small particles with a sufficient framerate and a method to prevent motion blur.
The most optimal components were found by performing a literature study. Calculations were made to test if the currently available hardware can fulfil the goals. A colleague created a short duration strobe light to prevent motion blur. Lastly, a practical test setup and MATLAB program were created to verify the theoretical conclusions and detect the lint.
The strobe light uses four high power white LEDs with a flash duration of one microsecond. The calculations have concluded that the currently available hardware is capable of fully representing the lint passing by at a minimum particle size of 45 microns. Analyses of the MATLAB program verified that the theoretical calculations were correct
- …
