Real-time cartesian force feedback control of a teleoperated robot

Active cartesian force control of a teleoperated robot is investigated. An economical microcomputer based control method was tested. Limitations are discussed and methods of performance improvement suggested. To demonstrate the performance of this technique, a preliminary test was performed with success. A general purpose bilateral force reflecting hand controller is currently being constructed based on this control method

Oral History Interview: Perry Campbell

This interview is one of a series conducted concerning West Virginia Vietnam veterans. In this interview, Perry Campbell discusses: his childhood experiences leading up to his military service; some regrets he has about military service; his thoughts on the draft and military service; serving in Germany (including getting shot at for helping East Germans escape to West Germany); his experiences as a weapons tester with various types of firearms; his experiences in Vietnam; his thoughts on the war; the VVA organization (Vietnam Veterans of America); wounded soldiers; his employment; psychological problems from the war; Walter Reed Army Hospital; an incident where he was reported dead; and other topics.https://mds.marshall.edu/oral_history/1048/thumbnail.jp

Black Girls in 3D Disruptive, Defiant, and Disrespectful: Case Studies of Culturally Responsive and Sustaining Classroom Management Practices in an Urban Middle School

Extensive research has been conducted on the disproportionate amount of suspensions that occur among Black boys, however, there is an emerging body of research that suggests that the rate of suspensions among Black girls is increasing. The most common behaviors that Black girls receive office referrals for, are subjective behaviors such as being disruptive, defiant, and disrespectful. (Nunn, 2018). The purpose of this study was to examine how Culturally Responsive Classroom Management (CRCM) strategies reduce the disproportionate amount of suspensions that Black girls received. This qualitative study conducted through case studies focused on how the teachers’ culturally responsive and sustaining classroom management practices impacted the discipline outcomes for Black girls. Grounded in the theoretical framework of culturally responsive pedagogy, CRCM brings social justice into school discipline and suggests that teachers’ perceived stereotypes, implicit bias, color blindness, and lack of cultural competency foster negative relationships between them and Black girls (Weinstein, Curran & Tomlinson-Clarke, 2003). The emerging findings from the study were teachers who were successful in employing CRCM possessed an intrinsic awareness about their students, built relationships with their students, code switched, and felt the responsibility of having a level of social consciousness about their students. The recommendations from this study to decrease the discipline gap that exists between children of color, especially Black girls, and their white peers are 1) provide continuous professional development on building cultural competence 2) provide continuous training on culturally responsive classroom management strategies and monitor them with fidelity and 3) make PBIS expectations culturally responsive & sustaining to fit the specific demographics of the school

Las cinco katas de Yagi Meitoku

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Effects of Altering Freshwater Chemistry on Physiological Responses of Rainbow Trout to Silver Exposure

The influence of different water Cl- (50–600 μM), Ca2+ (50–1,500 μM), Na+ (50–1,500 μM), or dissolved organic carbon (DOC, 0.31–5 mg/L) levels on silver-induced physiological and biochemical perturbations of rainbow trout were investigated. Fish were acclimated to soft water (50 μM; Cl-, Ca2+, and Na+), then exposed to 3.7 μg/L Ag (as AgNO3) for 6 h, which resulted in a reduction in Na+ influx from the water, an inhibition of gill sodium- and potassium-activated adenosine triphosphatase (Na+/K+-ATPase) activity, and an accumulation of silver on the gills. Increasing the water Cl- or DOC levels ameliorated the silver toxicity. However, increasing water Ca2+ or Na+ concentration did not reduce the silver-induced physiological and biochemical perturbations. The free silver ion (Ag+) concentrations (calculated from MINEQL+, a geochemical speciation computer program) showed a negative correlation with the Na+ influx rates and gill Na+/K+-ATPase activity. However, gill silver levels did not correlate to Ag+ concentrations and no correlation was found between gill silver levels and either Na+ influx rates or gill Na+/K+-ATPase activity. These results support the notion that the [Ag+] concentration is of major importance when assessing silver toxicity in fish, and that this should be taken into account in regulatory strategies for silver in the natural environment

Laser Ablation of Materials for Propulsion of Spacecraft

A report describes experiments performed as part of a continuing investigation of the feasibility of laser ablation of materials as a means of propulsion for small spacecraft. In each experiment, a specimen of ablative material was mounted on a torsion pendulum and irradiated with a laser pulse having an energy of 5 J. The amplitude of the resulting rotation of the torsion pendulum was taken to be an indication of the momentum transferred from the laser beam. Of the ablative materials tested, aluminum foils yielded the smallest rotation amplitudes of the order of 10 degrees. Black coating materials yielded rotation amplitudes of the order of 90 degrees. Samples of silver coated with a fluorinated ethylene propylene (FEP) copolymer yielded the largest rotation amplitudes 6 to 8 full revolutions. The report presents a theory involving heating of a confined plasma followed by escape of the plasma to explain the superior momentum transfer performance of the FEP specimens. It briefly discusses some concepts for optimizing designs of spacecraft engines to maximize the thrust obtainable by exploiting the physical mechanisms of the theory. Also discussed is the use of laser-ablation engines with other types of spacecraft engines