Geometry and Topology of Escape II: Homotopic Lobe Dynamics

We continue our study of the fractal structure of escape-time plots for chaotic maps. In the preceding paper, we showed that the escape-time plot contains regular sequences of successive escape segments, called epistrophes, which converge geometrically upon each endpoint of every escape segment. In the present paper, we use topological techniques to: (1) show that there exists a minimal required set of escape segments within the escape-time plot; (2) develop an algorithm which computes this minimal set; (3) show that the minimal set eventually displays a recursive structure governed by an ``Epistrophe Start Rule'': a new epistrophe is spawned Delta = D+1 iterates after the segment to which it converges, where D is the minimum delay time of the complex.Comment: 13 pages, 8 figures, to appear in Chaos, second of two paper

Geometry and Topology of Escape I: Epistrophes

We consider a dynamical system given by an area-preserving map on a two-dimensional phase plane and consider a one-dimensional line of initial conditions within this plane. We record the number of iterates it takes a trajectory to escape from a bounded region of the plane as a function along the line of initial conditions, forming an ``escape-time plot''. For a chaotic system, this plot is in general not a smooth function, but rather has many singularities at which the escape time is infinite; these singularities form a complicated fractal set. In this article we prove the existence of regular repeated sequences, called ``epistrophes'', which occur at all levels of resolution within the escape-time plot. (The word ``epistrophe'' comes from rhetoric and means ``a repeated ending following a variable beginning''.) The epistrophes give the escape-time plot a certain self-similarity, called ``epistrophic'' self-similarity, which need not imply either strict or asymptotic self-similarity.Comment: 15 pages, 9 figures, to appear in Chaos, first of two paper

EFFECT OF TYPE 3 BALL ON UPPER EXTREMITY EMG AND ACCELERATION IN THE TENNIS FOREHAND

The effect of the larger type 3 tennis ball on upper extremity EMG and impact acceleration was studied in a diverse sample of adult tennis players. Twelve players from intermediate to advanced levels of ability played no-add sets of six games using the larger and the regular tennis ball. Racket acceleration and upper arm muscle activation were measured during forehands with a Noraxon telemetry system. Within-subject statistical analysis showed that half of the players had significantly (p < 0.05) greater mean normalized-rectified EMG of the biceps or triceps with the larger ball compared to the regular ball. Half of the players with complete acceleration data also had significantly (p < 0.05) greater mean rectified acceleration after impact with the larger ball

INFLUENTIAL LITERATURE IN APPLIED SPORTS BIOMECHANICS

This study documented the perception of prestige of applied sports biomechanics journals, as well as influential articles and books. Recent ISBS members were surveyed to rate the quality/prestige of 35 journals. Descriptive statistics of ratings were calculated for respondents and correlated with the 2008 impact factor (IF) reported in the Journal Citation Reports. Mean ratings showed that international perception of influential journals were weakly (r = 0.48) correlated with the IF. These results confirm previous studies that the IF is a poor index for evaluating the influence of journals publishing applied sports biomechanics research, and there was considerable diversity among the respondent’s nominations of the most influential books and articles in the field

Mycobacterium bovis Bacillus Calmette-Guérin-Induced Macrophage Cytotoxicity against Bladder Cancer Cells

Many details of the molecular and cellular mechanisms involved in Mycobacterium bovis bacillus Calmette-Guérin (BCG) immunotherapy of bladder cancer have been discovered in the past decades. However, information on a potential role for macrophage cytotoxicity as an effector mechanism is limited. Macrophages play pivotal roles in the host innate immunity and serve as a first line of defense in mycobacterial infection. In addition to their function as professional antigen-presenting cells, the tumoricidal activity of macrophages has also been studied with considerable interest. Studies have shown that activated macrophages are potent in killing malignant cells of various tissue origins. This review summarizes the current understanding of the BCG-induced macrophage cytotoxicity toward bladder cancer cells with an intention to inspire investigation on this important but underdeveloped research field

BIOMECHANICS STUDENT’S LEARNING AND PERCEPTIONS OF LEARNING DUE TO THE COVID-19 PANDEMIC AND ASSOCIATED MITIGATION

The purpose of this study was to assess the effects of the COVID-19 pandemic and associated mitigation protocols on student learning and perceptions of learning in a biomechanics course. Students (n=31) enrolled in a three credit-hour biomechanics class in the Spring 2022 semester participated. Six questions related to the effects of mitigation protocols on student perceptions of learning. Three questions asked about to course-related student behaviours. Learning scores (g) were similar to those previously reported. Students believed that mitigation negatively affected getting to know and communicate with classmates (\u3e50%), they had to implement different learning strategies (55%), and learning mathematical concepts was more difficult due to the instructor wearing a face covering (45%). The student learning environment should be a consideration when deciding what mitigation protocols to implement if proposed in the future

Influence of Tall Fescue Baseball Infield Mowing Height on Ground Ball Speed

Athletic field conditions have been shown to influence playability. Results of ball-roll speed studies can be used to predict success of infield hits. Field trials were conducted at Rocky Ford Turfgrass Research Center, Manhattan, KS, to determine the influence of tall fescue baseball infield mowing height on ground ball speed and batter on-base success. Mowing heights of 1, 2, and 3 inches resulted in 1.77, 2.08, and 1.88 s ground ball times, respectively

A QUANTITATIVE COMPARISON OF TWO BIOMECHANCIS CONCEPT INVENTORY VERSIONS

This study quantified student responses between two different versions (1 and 3) of the Biomechanics Concept Inventory (BCI) assessment. Fifty students from a comprehensive university in the USA took both BCI versions on the first (pre) and last (post) day of an introductory undergraduate biomechanics course. Students scored significantly higher on BCI 3 for the post-test and gain score (i.e.: difference between pre and post). Eight of the twelve competency areas resulted in significantly different correct scores between versions. Correlations of competencies between versions ranged from -0.13 to 0.43, however, only two were significant. Discriminant analysis of the competency areas determined that BCI 1 predicted overall assessment performance better than BCI 3. The disparate results between versions should be considered in determining which to use

The Adsorption of Certain Vapors by Charcoal at Various Temperatures up to and above Their Critical Temperatures

It is perhaps safe to state that no one property of a solid substance has been more persistently studied through so long a period as has been the property of solid porous bodies to adsorb gases and vapors. The phenomenon of the adsorption of gases and vapors by charcoal was originally discovered independently by Scheele1 and by Fontana1 in 1777. In the century following much was contributed which deals with the general qualitative side of adsorption. It was not until the beginning of the present century and more particularly with the advent of poison gas warfare and the consequent demand for gas mask adsorbents that an intensive study of charcoal and its properties was undertaken. Since then many investigations have been made and a number of theories have been put forth in the attempt to explain the mechanism of adsorption and to deduce laws governing it

Status Report on Efforts to Enhance Instrumentation to Support Advanced Test Reactor Irradiations

The Department of Energy (DOE) designated the Advanced Test Reactor (ATR) as a National Scientific User Facility (NSUF) in April 2007 to support U.S. leadership in nuclear science and technology. By attracting new research users - universities, laboratories, and industry - the ATR NSUF facilitates basic and applied nuclear research and development, further advancing the nation's energy security needs. A key component of the ATR NSUF effort is to prove new in-pile instrumentation techniques that are capable of providing real-time measurements of key parameters during irradiation. To address this need, an assessment of instrumentation available and under-development at other test reactors was completed. Based on this review, recommendations were made with respect to what instrumentation is needed at the ATR; and a strategy was developed for obtaining these sensors. In 2009, a report was issued documenting this program’s strategy and initial progress toward accomplishing program objectives. In 2009, a report was issued documenting this instrumentation development strategy and initial progress toward accomplishing instrumentation development program objectives. This document reports progress toward implementing this strategy in 2010