A Naive View of the Russell Paradox

Two types of approximation to the paradoxical Russell Set are presented, one approximating it from below, one from above. It is shown that any lower approximation gives rise to a better approximation containing it, and that any upper approximation contains a distinct better approximation. The Russell Paradox is then seen to be the claim that two of these processes of better approximations stop, and at the same set. I claim that this shows the unrestricted Axiom of Comprehension to be, not a coherent intuition worthy of rescue from a mysterious paradox, but simply wishful thinking, a confusion of sets as extensional objects with classes defined by a property.Comment: 17 pages. Revised version of unpublished article referenced in Logique et Analyse, Vol 59, No 233 (2016) http://www.logic-center.be/Publications/Bibliotheque/SheridanVariantChurch.pd

Human upper limb manipulator mass center motion and mass moments of inertia variation

Motion control is complicated for people having traumas or neurological diseases. An underlying assumption in our work is that the motion of healthy people is optimal with respect to positioning accuracy, movement response, and energy expenditure. In this paper, a new approach for determination of the human upper limb mass-inertial characteristics is presented by using the 3D geometrical mathematical modeling analysis approach. Two examples will be given to illustrate the main features and advantages of the proposed design concepts. The objective of the work presented in this paper is a determination of the mass properties of a two joints human upper limb manipulator. Results are aimed to have application in an exoskeleton design, the design of manipulation system and external manipulation system, serving people with some motion difficulties, as well as in sport and rehabilitation

Analysis of finger motion coordination during packaging interactions

Packaging accessibility is a significant problem for many older people. Whilst the majority of studies have focused on issues surrounding strength, work has shown that dexterity required to open a pack is also a major issue for many older people. Hence, the work undertaken here, reports a quantitative study that aimed to analyse motion coordination patterns across digits 2–5 (index to little finger) during interactions with three of the most common types of packaging: plastic bottles, jars, and crisps packets, and comparing those interactions to a common measure of dexterity, the Perdue Pegboard. Ten subjects (6 males and 4 females) were examined while reaching forward to grasp and open a 300ml plastic bottle and a 500g jar. A ten-camera opto-electronic motion capture system measured trajectories of 25 miniature reflective markers placed on the dorsal surface landmarks of the hand. Joint angular profiles for 12 involved flexion–extension movements were derived from the measured coordinates of surface markers. The results showed that finger correlations vary widely across the differing pack formats with the crisps having the lowest finger movement correlation and the jar having the highest. Speed and jerk metrics were also seen to vary across the various pack formats. However, finger correlations were seen to be more relevant to perceived dexterity of pack opening than finger speeds and jerk motions

Chart Your Course

Library instruction is most effective when thoughtfully developed with faculty and integrated in a course. But how do you determine which faculty partnerships will have the most impact? In this poster, we discuss the process of curriculum mapping in an agriculture program, how it reveals new opportunities for library instruction, and pitfalls to avoid when charting your course. In fall 2016, librarians at the University of Tennessee Hodges Library and Pendergrass Agriculture and Veterinary Medicine Library developed learning outcomes for library instruction and services using feedback from staff and the ACRL Framework for Information Literacy. We mapped or coded the outcomes to learning objectives in the College of Agricultural Sciences and Natural Resources (CASNR) at the department and course level. We analyzed frequency patterns in the data to determine (a) which library outcomes are most important to CASNR undergraduate and graduate programs and (b) which departments and courses have the greatest overlap with library objectives. The patterns identified key players who would benefit most from additional library instruction, as well as gaps in instruction and resources. Finally, we developed visual mind maps to illustrate how library instruction supports the college and to serve as an outreach tool. Curriculum mapping is a useful exercise but not without challenges. Lessons learned include: be willing to train library staff on writing effective learning outcomes; investigate your institution’s ability and willingness to provide their objectives; and be flexible and consider alternative ways to connect with the curriculum

Online control of prehension predicts performance on a standardized motor assessment test in 8- to 12-Year-old children

Goal-directed hand movements are guided by sensory information and may be adjusted 'online,' during the movement. If the target of a movement unexpectedly changes position, trajectory corrections can be initiated in as little as 100 ms in adults. This rapid visual online control is impaired in children with developmental coordination disorder (DCD), and potentially in other neurodevelopmental conditions. We investigated the visual control of hand movements in children in a 'center-out' double-step reaching and grasping task, and examined how parameters of this visuomotor control co-vary with performance on standardized motor tests often used with typically and atypically developing children. Two groups of children aged 8-12 years were asked to reach and grasp an illuminated central ball on a vertically oriented board. On a proportion of trials, and at movement onset, the illumination switched unpredictably to one of four other balls in a center-out configuration (left, right, up, or down). When the target moved, all but one of the children were able to correct their movements before reaching the initial target, at least on some trials, but the latencies to initiate these corrections were longer than those typically reported in the adult literature, ranging from 211 to 581 ms. These later corrections may be due to less developed motor skills in children, or to the increased cognitive and biomechanical complexity of switching movements in four directions. In the first group (n = 187), reaching and grasping parameters significantly predicted standardized movement scores on the MABC-2, most strongly for the aiming and catching component. In the second group (n = 85), these same parameters did not significantly predict scores on the DCDQ'07 parent questionnaire. Our reaching and grasping task provides a sensitive and continuous measure of movement skill that predicts scores on standardized movement tasks used to screen for DCD