1,720,972 research outputs found
Friction is preferred over grasp configuration in precision grip grasping
No full textHow humans visually select where to grasp an object depends on many factors, including grasp stability and preferred grasp configuration. We examined how endpoints are selected when these two factors are brought into conflict: Do people favor stable grasps or do they prefer their natural grasp configurations? Participants reached to grasp one of three cuboids oriented so that its two corners were either aligned with, or rotated away from, each individual's natural grasp axis (NGA). All objects were made of brass (mass: 420g), but the surfaces of their sides were manipulated to alter friction: 1) all-brass, 2) two opposing sides covered with wood, and the other two remained of brass, or 3) two opposing sides covered with sandpaper, and the two remaining brass sides smeared with Vaseline. Grasps were evaluated as either clockwise (thumb to the left of finger in frontal plane) or counterclockwise of the NGA. Grasp endpoints depended on both object orientation and surface material. For the all-brass object, grasps were bimodally distributed in the NGA-aligned condition but predominantly clockwise in the NGA-unaligned condition. These data reflected participants' natural grasp configuration independently of surface material. When grasping objects with different surface materials, endpoint selection changed: Participants sacrificed their usual grasp configuration to choose the more stable object sides. A model in which surface material shifts participants' preferred grip angle proportionally to the perceived friction of the surfaces accounts for our results. Our findings demonstrate that a stable grasp is more important than a biomechanically comfortable grasp configuration. NEW & NOTEWORTHY When grasping an object, humans can place their fingers at several positions on its surface. The selection of these endpoints depends on many factors, with two of the most important being grasp stability and grasp configuration. We put these two factors in conflict and examine which is considered more important. Our results highlight that humans are not reluctant to adopt unusual grasp configurations to satisfy grasp stability.</p
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
A series of (un)predictable events: Influences of somatosensory predictions and action control on goal-directed movements
No full textEvery day, we move through our environment and interact with it. After switching off the alarm clock and drinking our first coffee, our day is filled with a wide variety of activities. For all these movements, the brain must select appropriate actions, formulate motor plans and process feedback from the body’s sensory systems. This entire process of executing a goal-directed movement is influenced by a multitude of factors. The aim of this dissertation is to investigate the influence sensorimotor predictions on perception and action in the context of goal-directed movements. A specific emphasis will be placed on sensorimotor predictions based on direct feedback signals, sensorimotor memories, and action control processes. The research is based on three studies and aims to elucidate the intricate interplay of sensory feedback, task relevance, and motor planning in executing precise and adaptable movements in varied contexts.
The first study explores how task-relevant feedback signals and their intensity modulate predictions based on efference copies during reaching. As a target is approached, there is a greater probability of physical contact with a surface, which in turn makes the tactile signals at the end of a movement more predictable. Feedforward prediction mechanisms can explain a resulting reduction of tactile sensitivity. However, previous research yielded contradictory findings, prompting the question of whether the relevance of feedback signals exerts a greater influence on the modulation of tactile perception than their mere predictability. My findings demonstrate that tactile suppression dynamically adjusts to the necessity of processing anticipated feedback, especially when the feedback signal is weak yet crucial for task completion. This highlights the brain's ability to selectively enhance sensory processing based on task demands.
The first study focusses on predictions based on current information, whereas my second study examines the influence of predictions derived from past sensorimotor memories on tactile perception and movement kinematics during the interaction with objects that possess uncertain properties. In the presence of uncertainty regarding object properties, humans tend to plan their movements based on their most recent experiences with that object. For example, when placing their fingers and grasping an object to prevent tilting, they usually repeat their grasping configuration in anticipation of constant object properties. In this instance, it is probable that one must compensate for errors in movement, thereby rendering incoming somatosensory signals crucial for the process of motor adjustments. My results indicate that while predictions based on sensorimotor memories significantly impact movement kinematics on a trial-by-trial basis, they do not similarly affect tactile sensitivity. This suggests that tactile perception necessitates a more stable informational foundation for sensorimotor predictions to exert an effective influence. Moreover, explicit knowledge about the change in object properties had no effect on either kinematic behavior or tactile sensitivity.
The third study aims to gain a deeper understanding of the extent to which predictions based on past somatosensory memories influence goal-directed movements. In this study, the focus is on a cognitive approach, specifically action control and predictions made on the basis of event files. A recent approach, the Binding and Retrieval in Action Control (BRAC) framework, aims to provide an overarching theory to explain results from different action control paradigms. This is achieved by using two core principles, feature binding and retrieval. My investigation revealed that previous experiences influence sensorimotor predictions, which in turn shape current motor planning. These results support the BRAC framework and highlight the importance of past interactions in shaping future actions, even in the context of complex motor tasks. It appears that goal-directed movements may serve as an effective means of integrating features of varying task-relevance and temporally varying accessibility.
Overall, this dissertation contributes to a deeper understanding of the mechanisms underlying goal-directed movements, emphasizing the importance of sensorimotor predictions based on current and past information and their influence on motor planning and execution
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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