1,720,956 research outputs found
Gait Detection in Children with and without Hemiplegia Using Single-Axis Wearable Gyroscopes
No full textIn this work, we develop a novel gait phase detection algorithm based on a hidden Markov model, which uses data from foot-mounted single-axis gyroscopes as input. We explore whether the proposed gait detection algorithm can generate equivalent results as a reference signal provided by force sensitive resistors (FSRs) for typically developing children (TD) and children with hemiplegia (HC). We find that the algorithm faithfully reproduces reference results in terms of high values of sensitivity and specificity with respect to FSR signals. In addition, the algorithm distinguishes between TD and HC and is able to assess the level of gait ability in patients. Finally, we show that the algorithm can be adapted to enable real-time processing with high accuracy. Due to the small, inexpensive nature of gyroscopes utilized in this study and the ease of implementation of the developed algorithm, this work finds application in the on-going development of active orthoses designed for therapy and locomotion in children with gait pathologies. © 2013 Abaid et al
Steady-State Poisson-Nernst-Planck Systems: Asymptotic expansions and applications to ion channels
Full text linkImportant properties of ion channels can be described by a steady state Poisson-Nernst-Plank system for electrodiffusion. The solution to the PNP system gives a relation between the current and electric potential of the ions in the channel, called the I-V curve. In this thesis, we will discuss the matched asymptotic expansions method of solving a singularly perturbed system and apply this method to find an approximate solution to the steady-state Poisson-Nernst-Planck system. In general, for nonlinear systems, it is impossible to obtain any representations of solutions. Due to the presence of a singular parameter in the PNP system, we can treat the system as a singularly perturbed problem. This system with specific nonlinearity has special structures that are crucial for the explicit higher order asymptotic expansions of the solutions. Although the ion channel problem considers only one cell, the I-V relation obtained in this thesis is consistent with the cubic-like assumption of the I-V relation in the FitzHugh-Nagumo model for action potential involving a population of ion channels. However, applications of the results of this thesis to ion channels are limited, since we considered a simplified model with two species of ions and a zero permanent charge in the channel
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
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
Collective Motion in Spatially Heterogeneous Environments
No full textThis dissertation investigates how spatial constraints influence collective motion through agent-based modeling and empirical analysis of animal behavior. We study how obstacles affect flocking, developed an agent-based model of bat flight from experimental data, and explored a model-free classification tool for swarming datasets. In the first study, we incorporated physical violation rules to an existing canonical flocking model to understand obstacle-induced perturbations to flocking behavior. The findings revealed that obstacles introduce non-monotonic phases of flocking. This non-monotonicity is tied to flock density, which is in turn mediated by noise and a characteristic length scale - the ratio of sensing radius to the obstacle radius. We found that particles need to sense in the order of the obstacle size to maintain global order. However, a high sensing radius can causes interlocked flocks to collide into virtual obstacles. Hence, while noise in the system generally frustrates global order, it is observed to facilitate flocking by breaking interlocked groups. Next, we extended the study to wildlife systems by analyzing the flight of gray bats. In this second study, we collected experimental data of bats flying in the absence and presence of environmental obstacles, and compared their flight under both conditions. Statistical and agent-based modeling of bat flight revealed that bats shift from spatial-memory driven channel-following behaviors to socially repulsive behavior in constrained spaces. Additionally, we found that obstacle avoidance dominates other interactions, suggesting that environmental feedback supersedes social cohesion under the stress of a novel environment. In the final study, we assessed swarming dynamics from 3D data projected into multiple 2D camera and pixel datasets to examine whether causal information can be retained in low-dimensional and noisy representations. Using midge swarming datasets, the analysis showed that EUGENE, the classification tool employed, performs better in constrained conditions such as cross-wind motion. This result implied that constrained dynamical systems are more sensitive to causal learning and similarity analyses. Overall, the studies in this dissertation reveal that spatial constraints, while limiting freedom of motion, accentuate local interactions and social structures. Counterintuitively, noise (or confusion) and reduced coordination may enhance collective motion in constrained environments.Doctor of PhilosophyThis dissertation explores how physical boundaries and obstacles influence the way groups move and work together. We simulated flocking motion with obstacles, built a mathematical model validated with an experimental dataset we collected, and examined techniques to understand similarities in group motion without the use of a model. In the first part, we simulated movement similar to how birds flock but added obstacles to ask: How much does a group member need to sense to maintain flocking? We found that each member needs to sense up to the size of an obstacle to flock in large groups. However, sensing too much can also frustrate flocking due to an interlocked state where everyone responds to an obstacle even if only some part of the group encounters it. In such cases, confusion in the group helps it break from this interlocked state and achieve better flocking. In the second part, we collected real-world data from gray bats, and compared the data of their flight in open space versus when we introduced obstacles in their flight paths. We learned that, in the absence of obstacles, bats followed familiar routes from spatial memory. However, when obstacles are introduced, the bats responded socially to their nearest neighbors by flying further from them. They also showed obstacle avoidance behaviors. This indicated that when facing new environments, animals prioritize social and environmental cues over memory. Finally, the third study examined whether complex group motion can still be differentiated using limited or low-quality data, such as 2D video recordings. We found that even limited data can be used to differentiate group motion. Even more so, we learned that datasets where motion is more restrictive is more identifiable. Together, these studies reveal that restrictions in the space, while frustrating order in the groups, can actually make social interactions more visible. Surprisingly, a little confusion or noise in such systems can improve coordination, and sometimes animals may even choose to separate from the group to possibly ease their navigation
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
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