Light Ball Research Articles

Aerodynamics in the classroom and at the ball park

Experiments suitable for classroom projects or demonstrations are described concerning the aerodynamics of polystyrene balls. A light ball with sufficient backspin can curve vertically upward through the air, defying gravity and providing a dramatic visual demonstration of the Magnus effect. A ball projected with backspin can also curve downward with a vertical acceleration greater than that due to gravity if the Magnus force is negative. These effects were investigated by filming the flight of balls projected in an approximately horizontal direction so that the lift and drag forces could be easily measured. The balls were also fitted with artificial raised seams and projected with backspin toward a vertical target in order to measure the sideways deflection over a known horizontal distance. It was found that (a) a ball with a seam on one side can deflect either left or right depending on its launch speed and (b) a ball with a baseball seam can also deflect sideways even when there is no sideways component of the drag or lift forces acting on the ball. Depending on the orientations of the seam and the spin axis, a sideways force on a baseball can arise either if there is rough patch on one side of the ball or if there is a smooth patch. A scuff ball with a rough patch on one side is illegal in baseball. The effect of a smooth patch is a surprising new observation.

Cluster formation in Hessdalen lights

In this paper we show a mechanism of light ball cluster formation in Hessdalen lights (HL) by the nonlinear interaction of ion-acoustic and dusty-acoustic waves with low frequency geoelectromagnetic waves in dusty plasmas. Our theoretical model shows that the velocity of ejected light balls by HL cluster is of about 104ms−1 in a good agreement with the observed velocity of some ejected light balls, which is estimated as 2×104ms−1.

A priori knowledge of the way the world works

Science is last place one might expect to find thought experiments. Thought experiments happen entirely in our minds, but science is supposed to tell us about how the world works. So how can something that happens entirely in our minds give us reason to believe anything about the nature of the world? This is the philosophical puzzle at the heart of James Robert Brown’s classic, The Laboratory of the Mind, now in its second edition. With two new chapters and extensive additions to two others, the single best introduction to the philosophical issues raised by thought experiments in science has just gotten better. Brown’s book can be usefully divided into three parts. Chapters 1–3 set forth the raw evidence that any theory of thought experiments must explain. These chapters introduce many examples of thought experiments and attempt to organize them in terms of how they work in science. Chapters 4 and 5 make the case for scientific Platonism. For Brown, thought experiments in science are successful because we are capable of acquiring a priori knowledge of the way the world works. Laws of nature are abstract objects that we have some sort of cognitive access to. The last three chapters, 6–8, display the power of Brown’s Platonism by applying it to scientific practice. This review will focus primarily on the first two parts of the book. The opening chapter offers a clear, patient and extremely valuable introduction to over a dozen important thought experiments. Chapters 2 and 3 set forth a perspicacious framework that taxonomizes thought experiments in terms of how they work epistemically in science. To understand the core of this taxonomy, it will be useful to begin with Brown’s favorite thought experiment. Galileo on Free Fall: Suppose, we attach a heavy cannon ball to a light musket ball and release them from a tower. If heavier bodies fall faster than lighter bodies, then the musket ball should

Kinetics of the upper limb during table tennis topspin forehands in advanced and intermediate players

The purpose of this study was to determine the significance of mechanical energy generation and transfer in the upper limb in generating the racket speed during table tennis topspin forehands. Nine advanced and eight intermediate table tennis players performed the forehand stroke at maximum effort against light and heavy backspin balls. Five high-speed video cameras operating at 200 fps were used to record the motions of the upper body of the players. The joint forces and torques of the racket arm were determined with inverse dynamics, and the amount of mechanical energy generated and transferred in the arm was determined. The shoulder internal rotation torque exerted by advanced players was significantly larger than that exerted by the intermediate players. Owing to a larger shoulder internal rotation torque, the advanced players transferred mechanical energy from the trunk of the body to the upper arm at a higher rate than the intermediate players could. Regression of the racket speed at ball impact on the energy transfer to the upper arm suggests that increase in the energy transfer may be an important factor for enabling intermediate players to generate a higher racket speed at impact in topspin forehands.

Relation between general throwing tests with a medicine ball and specific tests to evaluate throwing velocity with and without opposition in handball

Rivilla-Garcia J, Martinez I, Grande I, Sampedro-Molinuevo J. Relation between general throwing tests with a medicine ball and specific tests to evaluate throwing velocity with and without opposition in handball. J. Hum. Sport Exerc. Vol. 6, No. 2, pp. 414-426, 2011. The aim of the present study was to analyze the relationship among general throwing tests, with a medicine ball, and throwing velocity tests with and without opposition in different groups of handball players, thus analyzing the influence of technique and decision making in specific throwing capacity. To do this, ninety-four handball players of different competitive levels, age groups and playing positions were tested in four throws of progressive specificity: a) throwing with a heavy medicine ball (THMB); b) throwing with a light medicine ball (TLMB); c) throwing velocity (VS); and d) throwing velocity with opposition (VO). The correlational study, using Pearson's correlation coefficient, was found to be significant (p<0.01) in the relations among the different tests in the whole sample and all groups. The data indicated not very high correlations between the THMB and the other tests, especially with the VO in the over 18 senior players (r=0.404**). Correlation values for TLMB-VS were very high in general (r=0.904**) and in all groups. By contrast, the correlation between the throwing tests was not high, especially in the under 18 players (r=0.621**), backcourt players (r=0.632**) and central players (r=0.594**). The data lead to the conclusion that the general test has limited utility for assessing specific throwing capacity; that TLMB adequately predicts VS; and that opposition has a significant influence on specific throwing speed. Key words: TEST, SPECIFIC FITNESS, OPPOSITION, DECISION-MAKING. 1 Corresponding author. C/. Ma Auxiliadora, 13 – 2o. Puertollano (Ciudad Real) C.P. 13500, Spain.

Disreputable Young Ladies at Play

It was no coincidence that notable baseball club of young ladies took field in upstate New York village of Peterboro. The sponsors were well known political figures, committed to cause of equal rights for women. Gerrit Smith was as radical as he was wealthy, an old friend of Frederick Douglass John Brown. In spring of 1851, Smith's daughter, Elizabeth Miller, disgusted with difficulty of working in long skirts of period, had designed more comfortable outfit, consisting of Turkish trousers beneath short dress. Her idea was soon adopted by other feminists, including her cousin, Elizabeth Cady Stanton, their friend Amelia Bloomer, who popularized costume in her magazine, The Lily.1Conservative commentators of both sexes dismissed notion of sharing nation's diamonds with women. A columnist for Ladies' Repository listed number of suitable outdoor activities for girls, but stated flatly that Base Ball would seem so far out of line of feminine pursuits that nothing need be said of it.2 Mr. Hooper of Appleton's Magazine argued that National Pastime's moral influence was shown by its exclusion of opposite sex, noting proudly that women are soliciting office demanding franchise, base ball clubs are only accessible to men.3The new organization was there to give them lie. Word of their innovation spread quickly, thanks to Mrs. Cady Stanton, who shared news with her many contacts in press. On August 13, 1868, Buffalo Courier Republic summarized her report, noting that Nannie Miller, granddaughter of Gerrit Smith's, is captain, handles bat with grace strength worthy of note. It was pretty sight to see girls with their white dresses blue ribbons flying, in full possession of public square last Saturday afternoon, while boys were quiet spectators of scene. An engraved illustration, showing club at play, helped reinforce message.4Others soon adopted notion. The following season, Cincinnati, home of undefeated Red Stockings, also hosted club entirely of young ladies, who play very well.5 In Evansville, Illinois, students of female seminary followed suit. call themselves Dianas, noted Oliver Optic's Magazine, and they lately received challenge from Baltic club of Chicago, Juniors.6 The movement spread as far south as Columbus, Georgia, in 1872, Appleton's reported that the swiftest 'pitch' in country is young woman, aged 23, belonging to Minnesota female base ball club.7In early 1870s, focus of organized baseball shifted from clubs of gentlemen amateurs (more or less) to lineups composed of best available professional players. In fall of 1875, readers of New York Clipper, which featured sports theater, learned thatthe latest commotion in base ball line is formation of club composed of young ladies-9 blondes 9 brunettes-at Springfield, Ill. The originators of idea, Frank Myers, S. B. Brock, Thomas Halligan, under impression that there is money in it, propose to give exhibitions in principal cities, depending on novelty of thing to render it success.8The first game of baseball ever played in public for gate money between feminine ball-tossers took place in Illinois capital on September 11. The press was advised that players were a selected troupe of girls of reputable character who have shown some degree of aptitude in ball playing. The Clipper's correspondent noted thatboth clubs wear handsome new uniform, which does not differ materially from those worn by ordinary clubs. The Brunettes wear white suits trimmed with blue. The Blondes wear blue suits trimmed with white. They also have light leather gloves, use lighter ball than that required by rules. The bases field are trifle over half ordinary field, bases being only 50 feet apart. …

A hypothetical dusty plasma mechanism of Hessdalen lights

Hessdalen lights (HL) are unexplained light balls usually seen in the valley of Hessdalen, Norway. In this work, it is suggested that HL are formed by a cluster of macroscopic Coulomb crystals in a plasma produced by the ionization of air and dust by alpha particles during radon decay in the dusty atmosphere. Several physical properties (oscillation, geometric structure, and light spectrum) observed in HL phenomenon can be explained through the dust plasma model.

Dancing with a Ball of Light

Dancing with a Ball of Light

Ultrasonic levitation.

Ultrasonic standing waves are set up between a horn and a brass plate. Because the wavelength is short, several wavelengths fit in the space between the horn and the plate. There are locations in the standing wave pattern where the forces associated with the sound pressure and the motion of the air molecules are opposite in direction to the gravitational force. A light ball placed at any of these locations will levitate if the mass of the ball is such that the gravitational force on the ball is equal and opposite to the forces associated with the pressure and the motion of the air molecules.

Sound of a ball spline operated at a certain linear velocity

This article deals with the sound of light or medium-preloaded ball splines operating at a certain linear velocity. Experimental results showed that the sound waveforms of the ball splines are pulse-like with ball passage period Tp, and sound peaks f1- f8 and f1- f7 appear in the 20 kHz range sound spectra of the light- and medium-preloaded ball splines, respectively. A supplemental experiment showed that the main cause of the ball spline sound is the collision between the ball and the spline shaft or spline nut at the entrance of the load zone. The measured frequencies of the sound peaks nearly matched the natural radial-bending frequencies of the spline shaft or nut obtained by finite-element method (FEM). This means that the sound peaks are caused by the natural radial-bending vibrations of the spline shaft and nut. Finally, based on the experimental and FEM results, the sound-generating mechanism of the ball splines has been elucidated.

Glycosaminoglycans Facilitate Procathepsin B Activation through Disruption of Propeptide-Mature Enzyme Interactions

Lysosomal cysteine cathepsin B participates in numerous diverse cellular processes. In acquiring its activity, the proregion, which blocks the substrate-binding site in the proenzyme, needs to be cleaved off. Here we demonstrate that polyanionic polysaccharides, glycosaminoglycans (GAGs), can accelerate the autocatalytic removal of the propeptide and subsequent activation of cathepsin B. We show that naturally occurring GAGs such as chondroitin sulfates and heparin, as well as the synthetic analog dextran sulfate, accelerate the processing in a concentration-dependent manner. Heparin oligosaccharides down to the size of tetrasaccharides were efficient in accelerating the procathepsin B processing, whereas disaccharides were without effect. Further, the ability of the GAGs to accelerate procathepsin B processing was sensitive to increasing NaCl concentrations, indicating that electrostatic interaction between the GAGs and procathepsin B are operative in the accelerating effect. Also the processing of the catalytic procathepsin B mutant by wild type cathepsin B was enhanced in the presence of GAGs, suggesting that GAGs induce a conformational change in procathepsin B, converting it into a better substrate. Site-directed mutagenesis showed that His(28), Lys(39), and Arg(40), located within the procathepsin B propeptide, have significant roles in the acceleration of procathepsin B activation induced by short GAGs. Because procathepsin B and GAGs often co-localize in vivo, we propose that GAGs may play a physiological role in the activation of procathepsin B.

Baseball

In this study we compared the kinematic features of the throwing motion between young baseball players of different age groups. Forty‐four Japanese baseball players aged 6.1 to 12.3 years who regularly played baseball, including pitchers and position players, had their throwing actions analyzed three‐dimensionally using high speed videography. Of this sample, 26 players aged above 9 years of age were categorized as the senior group, while the remaining 18 were categorized as the junior group. Senior group throwers had greater height and body mass, and produced a greater ball speed than junior group throwers. The throwing arm movement of senior group throwers was similar to that of adult skilled players. However, in the junior group throwers, the shoulder horizontal adduction angle was larger during the arm acceleration phase, and the maximum angular velocities of elbow extension and shoulder internal rotation occurred later than in senior group throwers. These results indicate that players aged above 9 years can acquire a mature throwing arm movement, while players younger than that will use an immature motion. A possible reason why these differences were shown is that the official baseball is relatively heavy for junior group throwers; they would be better advised to use a lighter ball in throwing practice.

Orbs, Blobs, and Glows: Astronauts, UFOs, and Photography

Neil Armstrong saw UFOs: two pale orbs haloed in a cobalt glow hovering in a pitch-black void. Or so countless websites report in copy-and-paste narratives replete with audio, tiny fuzzy color images, and corroborations by ex-NASA employees, doctors, and even one of Neil's friends. In photographs of UFOs taken by astronauts, two divergent worlds come into the same orbit: science and the paranormal. Astronomers and ufologists both gaze into outer space, but with very different desires. The claim that our national hero Armstrong saw a UFO is either the most alluring evidence of alien intelligence out there or the most absurd. Other pixelated images purportedly taken by Armstrong show a ball of light over a spaceship on the lunar surface and a seahorse-shaped blob high above earth. There they are: July 1969, alone on a cold gray ball 238,000 miles from our planet, out of range of any cameras except the ones they hold, highly trained and imbued with impeccable authority, and invested with all the dreams and aspirations of an entire nation.

Comparison of Implicit and Explicit Learning Processes in a Probabilistic Task

This experiment compared the performance with explicit (rule-application and rule-discovery) and implicit (nonrule-instructed) learning approaches on the performance of a probabilistic video game task requiring fine motor control. The task required visual tracking of a small ball of light and "catching" it by means of joystick manipulation. A general pattern of improvement with practice occurred for all conditions. All conditions showed use of predictive relations among stimulus events. However, task performance of the rule-application and rule-discovery conditions were inferior to the nonrule-instructed implicit condition, particularly during the early phases of rule acquisition and application. This pattern strongly suggests substantial performance costs associated with attempting to discover or apply probabilistic rules. Decrements are likely due to increased cognitive demands associated with attempting to remember and strategically apply provided probability rules or attempting to discover and apply potentially important and useful probability information from a complex visual display.

Immediate effect of assisted and resisted training using different weight balls on ball speed and accuracy in baseball pitching

The purpose of this study was to investigate the immediate effects of assisted and resisted training using different weight balls on ball speed and accuracy in baseball pitching. Eight male university baseball players were assigned as subjects. The experiment used a standard 145-gram baseball and two heavier or lighter balls with weights increased or decreased by 10% respectively. The subjects were required to pitch these balls and/or standard ball either six or eighteen times under different training trial conditions: 1) pitching the weighted ball only, 2) pitching the lightened ball only, 3) pitching the standard ball only, and 4) pitching three kinds of balls in order of the weighted, standard and lightened balls. Immediately after each training trial, the standard ball was pitched five times respectively (test trial). The ball speed of each trial was measured with a speed gun, and the distance from the center of target to the position of the ball pitched on the target was calculated using a video digitizing system. The results are summarized as follows: 1) In the training trials, the ball speed increased as the ball weight was decreased. 2) In the test trials, immediately after pitching the lightened ball both six (6Atest) and eighteen times (18Atest), and the three different kinds of balls eighteen times (18Ctest), the ball speeds were seen to be significantly higher than that of other test trials (p<0.01). 3) Although there were no significant differences in the ball speed in the above three test trials, a relatively higher ball speed was observed in 18Atest. 4) As for the distance from the center of target to the position of the ball pitched on the target, there were no significant differences among any trials.

COMPARISON OF IMPLICIT AND EXPLICIT LEARNING PROCESSES IN A PROBABILISTIC TASK

This experiment compared the performance with explicit (rule-application and rule-discovery) and implicit (nonrule-instructed) learning approaches on the performance of a probabilistic video game task requiring fine motor control. The task required visual tracking of a small ball of light and “catching” it by means of joystick manipulation. A general pattern of improvement with practice occurred for all conditions. All conditions showed use of predictive relations among stimulus events. However, task performance of the rule-application and rule-discovery conditions were inferior to the nonrule-instructed implicit condition, particularly during the early phases of rule acquisition and application. This pattern strongly suggests substantial performance costs associated with attempting to discover or apply probabilistic rules. Decrements are likely due to increased cognitive demands associated with attempting to remember and strategically apply provided probability rules or attempting to discover and apply potentially important and useful probability information from a complex visual display.

Development and validation of two new sensory tests of the hand for patients with stroke.

To establish validity and reliability of two new sensory tests evaluating moving (MTP) and sustained (STP) touch-pressure and their relationship to hand function for patients with stroke. The STP had four components in which a light or heavy ball was applied passively or held actively. Twenty-eight participants with hemiparesis (1-109 months) from rehabilitation hospitals or outpatient programmes. Content validity was established. Then reliability and concurrent and construct validity were determined. Sensation was compared with hand functional ability using the Modified Moberg recognition task, the Box and Block test and one task of the TEMPA test. Reliability: Both types of reliability were significant for MTP (ICC = 0.92) and all components of STP (ICC = 0.62 to 0.92). Concurrent validity: MTP and STP correlated significantly (r = -0.39 to -0.83) with the Semmes-Weinstein Monofilament test used as a 'gold standard' comparison. Construct validity: MTP was significantly related to Moberg (r = 0.49). Three of four components of STP correlated with TEMPA (r = 0.49-0.53) and Moberg (0.45-0.71). Only STP (heavy ball) correlated with Box and Block (0.42-0.48). Of the four components of STP, only the passive STP (light ball) was not related to hand function. The new sensory tests of moving, and three components of sustained touch-pressure were reliable. The passive STP (light ball) was discarded. All but this test were relevant to the two functional roles of sensation: exploration for MTP and dexterity during holding for STP.

Inter- and intra-limb generalization of adaptation during catching.

We have previously shown that healthy adults require a few trials to adapt to a changed ball weight during catching. It is not known whether this adaptation generalizes to the opposite arm or to different configurations of the same arm. We tested healthy adult subjects catching balls of different weight while maintaining the hand within a vertical spatial "window." In experiment 1, subjects caught a series of light and heavy balls, first with one hand and then with the other. In experiment 2, subjects caught a series of light and heavy balls, first with the catching arm in either a "bent" or a "straight" configuration and then with the same arm in the other configuration. A percentage transfer value was calculated to determine the degree to which previous experience with a given ball weight in one context affected performance of the same task in a new context (i.e., different arm or different arm configuration). Results showed that generalization occurred both between arms and within an arm. However, the subjects who switched arms showed less generalization than those who switched arm positions. Specifically, the percentage transfer value for subjects who switched arms was 58%, while the percentage transfer for those who switched arm positions was 100%. These results support the idea that the motor system is able to generalize adaptive control of ball catching to the contralateral arm and to different arm configurations. Our findings are also in agreement with the recent notion that multiple internal representations of a task may exist in the CNS. Because there was partial generalization between the two arms, we conclude that there must be a representation stored and used for catching that is not effector specific, but rather can be utilized by brain regions controlling either arm. However, because generalization was only complete within an arm, we conclude that another sensorimotor representation exists, which might only be stored in brain regions specific to a single arm.

Correlations between physiological parameters and performance in elite ten-pin bowlers

The increasing acceptance of ten-pin bowling as a sport, as well as the keen competition amongst bowlers, necessitates the identification of performance indicators to aid training. The aim of this cross-sectional study was to determine if age, height, weight, aerobic power index, bowling grip strength, 10-RM leg press performance, and the sit-and-reach distance correlated with bowling performance in 42 elite bowlers (26 males and 16 females). At the same time, the physiological profiles of bowlers classified as heavy ball strokers, heavy ball crankers, and light ball spinners were compared. The results showed that for the male bowlers, none of the parameters correlated with performance, while for the female bowlers, the only parameter that correlated with performance was the aerobic power index. Bowlers using the three different releases had similar anthropometric and physiological profiles. The implications from this study are that bowlers of diverse age and build can be equally competitive in the sport; that aerobic capacity (as reflected by the aerobic power index) may, to a certain extent, contribute to bowling performance; and that strength and flexibility measures do not seem to be useful performance indicators amongst elite bowlers.

Cerebellar subjects show impaired adaptation of anticipatory EMG during catching.

We evaluated the role of the cerebellum in adapting anticipatory muscle activity during a multijointed catching task. Individuals with and without cerebellar damage caught a series of balls of different weights dropped from above. In Experiment 1 (light-heavy-light), each subject was required to catch light balls (baseline phase), heavy balls (adaptation phase), and then light balls again (postadaptation phase). Subjects were not told when the balls would be switched, and they were required to keep their hand within a vertical spatial "window" during the catch. During the series of trials, we measured three-dimensional (3-D) position and electromyogram (EMG) from the catching arm. We modeled the adaptation process using an exponential decay function; this model allowed us to dissociate adaptation from performance variability. Results from the position data show that cerebellar subjects did not adapt or adapted very slowly to the changed ball weight when compared with the control subjects. The cerebellar group required an average of 30.9 +/- 8.7 trials (mean +/- SE) to progress approximately two-thirds of the way through the adaptation compared with 1.7 +/- 0.2 trials for the control group. Only control subjects showed a negative aftereffect indicating storage of the adaptation. No difference in performance variability existed between the two groups. EMG data show that control subjects increased their anticipatory muscle activity in the flexor muscles of the arm to control the momentum of the ball at impact. Cerebellar subjects were unable to differentially increase the anticipatory muscle activity across three joints to perform the task successfully. In Experiment 2 (heavy-light-heavy), we tested to see whether the rate of adaptation changed when adapting to a light ball versus a heavy ball. Subjects caught the heavy balls (baseline phase), the light balls (adaptation phase), and then heavy balls again (postadaptation phase). Comparison of rates of adaptation between Experiment 1 and Experiment 2 showed that the rate of adaptation was unchanged whether adapting to a light ball or a heavy ball. Given these findings, we conclude that the cerebellum is important in generating the appropriate anticipatory muscle activity across multiple muscles and modifying it in response to changing demands though trial-and-error practice.