White Balls Research Articles

Instruction-based selective action pattern (IBSAP): a novel method for talent identification in sports

Background and Study Aim: Talent identification/development programs are utilized by sports federations to select or train elite athletes. In addition to the established tests that assess perceptive and motor skills, it was deemed significant that cognitive skills should be evaluated as well. The present study was undertaken to assess the utility of Instruction-Based Selective Action Pattern (IBSAP), a novel method that we developed, in estimating perceptive, motor as well as cognitive skills of athletes in order for talent identification. We also investigated the relationship between IBSAP and auditory reaction times (ARTs). Material and Methods: Forty-three students (average age: 12.6 years) participated in the study. Random/fixed-interval ARTs were recorded. IBSAP was applied using a table tennis robot that was set up to throw 30 balls in three different colors to different spots on the table with a frequency of 1 ball/s. The subjects were instructed to ignore the white balls, to touch the yellow balls, and to catch the pink balls before the first trial and their scores were calculated in two consecutive trials according to a scoring system. Results: Our results showed that motor learning, adaptation and reinforcement of the participants were significantly greater in second trial compared with the first trial and that IBSAP values were correlated with ARTs. Conclusions: We conclude that the IBSAP method reliably provides quantitative data on perception, motor as well as cognitive skills and it can be considered as a useful tool for talent identification.

Distributions in the constant-differentials Pólya process

We study a class of unbalanced constant-differentials Pólya processes on white and blue balls. We show that the number of white balls, the number of blue balls, and the total number of balls, when appropriately scaled, all converge in distribution to gamma random variables with parameters depending on the differential index and the amount of ball addition at the epochs, but not on the initial conditions. The result is obtained by an analytic approach utilizing partial differential equations. We present a martingale formulation that may provide alternatives.

Effect of Micro-Zone pH Gradient on AM60B Vanadate Film and Corrosion Behavior

To further study the formation and corrosion mechanisms of AM60B vanadate films, a vanadate coating was synthesized on AM60B substrate via a chemical conversion at 50°C. The morphologies of the films and the corrosion samples were observed by using scanning electron microscopy(SEM), energy dispersive X-ray analysis(EDAX) was used to analyze the elemental distribution of the film surface and the Electrochemical Impedance Spectroscopy(EIS) and the polarization curves of the films were tested by an electrochemical workstation. The morphology of conversion film is layered structure with white balls. V element preferentially deposits near the base end and the V-rich phase is easily generated on the β-phase(Mg17Al12). In the course of corrosion, corrosion begins near the α-phase(Mg). During the processes of observation and analysis, the concept of micro-zone pH gradients was discovered and applied, and attempts were made to explain some observed phenomena by using this concept. The results show that the concept of pH gradients in micro zones can be used to explain the film formation and corrosion mechanisms well.

A TIME-DEPENDENT PÓLYA URN WITH MULTIPLE DRAWINGS

In this paper, we consider a generalized Pólya urn model with multiple drawings and time-dependent reinforcements. Suppose an urn initially contains w white and r red balls. At the nth action, m balls are drawn at random from the urn, say k white and m−k red balls, and then replaced in the urn along with cnk white and cn(m − k) red balls, where {cn} is a given sequence of positive integers. Repeat the above procedure ad infinitum. Let Xn be the proportion of the white balls in the urn after the nth action. We first show that Xn converges almost surely to a random variable X. Next, we give a necessary and sufficient condition for X to have a Bernoulli distribution with parameter w/(w + r). Finally, we prove that X is absolutely continuous if {cn} is bounded.

High hardness-toughness and wear resistance of white cast iron treated by a multicycle quenching-partitioning-tempering process

ABSTRACTBased on a multicycle quenching-partitioning-tempering process, a novel process is proposed to treat Fe–2.4C–12.0Cr (mass %) white cast iron balls. It is a destabilizing heat treatment following multicycle quenching and sub-critical treatment (De-MQ-Sct) process. Such a complex process may be simply performed by alternate water quenching and air cooling. For comparison, the white cast iron balls also were treated by conventional normalization (NOR) process and oil-quenching process. The partitioning of carbon from martensite to retained austenite during the De-MQ-Sct process promotes the interaction between carbide precipitation and martensitic transformation. While this interaction is a unique effect only produced by multicycle quenching linking destabilizing and sub-critical treatments, which leads to more, and finer, secondary carbides and more carbon-enriched austenite in De-MQ-Sct sample than those in a NOR or oil-quenching sample. The average hardness of 60 HRC and impact toughness of 12.6 J/cm2 are obtained in De-MQ-Sct white cast iron balls, which are much higher than those in a NOR and oil-quenching ones. The wear behavior measured by pin-on-disk wear tests indicate that the weight loss of De-MQ-Sct sample is only about one-third of the NOR sample and one half of the oil-quenching sample. Microstructural characterization reveals that high hardness-toughness and wear resistance of the De-MQ-Sct balls are mainly attributed to the large quantities of fine secondary carbides and stable carbon-enriched retained austenite.

Pólya urns with immigration at random times

We study the number of white balls in a classical Pólya urn model with the additional feature that, at random times, a black ball is added to the urn. The number of draws between these random times are i.i.d. and, under certain moment conditions on the inter-arrival distribution, we characterize the limiting distribution of the (properly scaled) number of white balls as the number of draws goes to infinity. The possible limiting distributions obtained in this way vary considerably depending on the inter-arrival distribution and are difficult to describe explicitly. However, we show that the limits are fixed points of certain probabilistic distributional transformations, and this fact provides a proof of convergence and leads to properties of the limits. The model can alternatively be viewed as a preferential attachment random graph model where added vertices initially have a random number of edges, and from this perspective, our results describe the limit of the degree of a fixed vertex.

Endogenous Endophthalmitis by <i>Candida Albicans</i> Associated with a Primary Immunodeficiency Due to CARD9 Deficiency

This report encopasses a case of endogenous endophthalmitis by <i>Candida albicans</i> in an otherwise healthy young adult patient, which led to the diagnosis of a primary immunodeficiency, CARD9 deficiency, associated with familial candidiasis. A 31-year-old female patient with a one-month history of low visual acuity (VA) in the right eye (RE) was referred after no response to treatment of toxoplasmosis and acute retinal necrosis. She presented no comorbidities, but a history of recurrent paronychia, oral candidiasis and <i>tinea capitis</i> since childhood. Her parents were first-degree cousins. Visual acuity was 20/2000 in the RE and 20/20 in the left eye (LE). There was an elevated exudative lesion occupying the retinal posterior pole, associated with fluffy white cotton balls in the adjacent posterior vitreous. Optical coherence tomography (OCT) showed macular lesions with the "rain cloud" sign. Fungal endogenous endophthalmitis was hypothesized. Imaging and laboratory examinations discarded other infections and eliminated involvement of other organs. Diagnostic vitreous puncture was performed in addition to Amphotericin B injection and intravenous Fluconazole. As culture results were negative, a vitreous biopsy was performed, in which <i>Candida albicans</i> was grown, followed by a second Amphotericin B injection. As there was no improvement, pars plana posterior vitrectomy, with placement of silicone oil, was performed. In spite of infection control, VA remained 20/2000. Due to a severe ocular condition with no other invasive sites of infection, associated with superficial recurrent fungal infections, a primary fungal specific immunodeficiency was suspected, resulting in referral to Immunology. An immunogenetic panel was performed, demonstrating heterozygosity for two CARD9 gene mutations, a molecule related to familial candidiasis. Follow-up in Ophthalmology and Immunology was maintained and oral Fluconazole was proposed to be taken for at least 6 months. Three months later, she presented with an oral abscess secondary to <i>Candida</i>, managed by the Otorhinolaryngology team. Fungal endogenous endophthalmitis is an important cause of morbidity and low visual acuity, especially in the population of immunocompromised patients. Early ophthalmological diagnosis should preferably be performed in order to prevent lesions from increasing, affecting noble areas such as the macula, and reaching the vitreous. When the fundus exam presents signs of fungal endophthalmitis in immunocompetent, young and healthy patients, diagnosis of primary immunodeficiencies should be considered.

Proof Without Words: Tetrahedral Bond Angle

From this steady configuration of four identical white balls (supported by weightless sticks) on a balance, simulating the methane molecule CH4 , we conclude that the angle subtended by any two ver...

A self-equilibrium Friedman-like urn via stochastic approximation

In this study, we propose a class of generalized Friedman urns with random entries. The class has the property of self-equilibrium. We prove the almost-sure convergence to the equilibrium point of this entire class by the method of stochastic approximation. We develop a central limit theorem for the proportion of white balls through the convergence theorem of stochastic approximation algorithms. We then apply this class of schemes to model the effect of trading on the price in the stock market under the efficient market hypothesis.

A generalized urn with multiple drawing and random addition

In this paper, we consider an unbalanced urn model with multiple drawing. At each discrete time step n, we draw m balls at random from an urn containing white and blue balls. The replacement of the balls follows either opposite or self-reinforcement rule. Under the opposite reinforcement rule, we use the stochastic approximation algorithm to obtain a strong law of large numbers and a central limit theorem for $$W_n$$ : the number of white balls after n draws. Under the self-reinforcement rule, we prove that, after suitable normalization, the number of white balls $$W_n$$ converges almost surely to a random variable $$W_\infty $$ which has an absolutely continuous distribution.

Mate-searching behavior of the black chafer Holotrichia kiotonensis (Coleoptera: Scarabaeidae): identification of a sex pheromone, and male orientation behavior controlled by olfactory and visual cues

In the black chafer Holotrichia kiotonensis Brenske (Coleoptera: Scarabaeidae), mating behavior was observed between 1940 and 2010 hours at < 0.1 lx in both the laboratory and the field. In the laboratory, an ether extract of female abdominal glands induced a series of pre-mating behaviors such as short-distance orientation and abdominal bending. When the extract was fractionated by silica gel column chromatography, the active fraction was eluted with 50% ether in hexane and 100% ether. Gas chromatography–mass spectrometry analysis revealed that both active fractions contained anthranilic acid (2-amino-benzoic acid) as a major compound. The amount of this compound was determined to be ca. 600 ng/female by high performance liquid chromatography analysis with a fluorescence detector. In the field, male chafers were observed to land on cotton balls impregnated with 10 mg of authentic anthranilic acid. When a white ball treated with anthranilic acid was placed 2–10 cm away from an untreated black ball, males were observed to land significantly more frequently on the latter. These results suggest that males could recognize white balls below 0.1 lx and landed on black balls. When a treated black ball was placed beside an untreated black ball, more males landed on the former. The difference was significant when the distance between the two lures was 5 or 10 cm, but not significant when it was 2 cm. These observations demonstrated that anthranilic acid was the sex-attractant pheromone for the black chafer H. kiotonensis and that the males located and landed on a pheromone source by using olfaction in conjunction with visual orientation. The importance of visual orientation in this nocturnal species is discussed in comparison with the congeneric diurnal species Holotrichia loochooana loochooana.

Two-color balanced affine urn models with multiple drawings

We study a class of balanced urn schemes on balls of two colors (say white and black). At each drawing, a sample of size m≥1 is taken out from the urn, and ball addition rules are applied. We consider these multiple drawings under sampling with or without replacement. We further classify ball addition matrices according to the structure of the expected value into affine and nonaffine classes. We give a necessary and sufficient condition for a scheme to be in the affine subclass, for which we get explicit results for the expected value and second moment of the number of white balls after n steps and an asymptotic expansion of the variance. Moreover, we uncover a martingale structure. This unifies several earlier works focused on special cases of urn models with multiple drawings [5,6,17,19,20,22] as well as the special case of sample size m=1. The class is parametrized by Λ, specified by the ratio of the two eigenvalues of a “reduced” ball replacement matrix and the sample size. We categorize the class into small-index urns (Λ<12), critical-index urns (Λ=12), and large-index urns (Λ>12), and triangular urns. We obtain central limit theorems for small- and critical-index urns and prove almost-sure convergence for triangular and large-index urns. Moreover, we discuss the moment structure of large-index urns and triangular urns.

Large deviations for generalized Polya urns with arbitrary urn function

We consider a generalized two-color Polya urn (black and white balls) first introduced by Hill et al. (1980), where the urn composition evolves as follows: let π:0,1→0,1, and denote by xn the fraction of black balls after step n, then at step n+1 a black ball is added with probability πxn and a white ball is added with probability 1−πxn. Originally introduced to mimic attachment under imperfect information, this model has found applications in many fields, ranging from Market Share modeling to polymer physics and biology.In this work we discuss large deviations for a wide class of continuous urn functions π. In particular, we prove that this process satisfies a Sample-Path Large Deviations principle, also providing a variational representation for the rate function. Then, we derive a variational representation for the limit ϕs=limn→∞1nlogPnxn=sn,s∈0,1,where nxn is the number of black balls at time n, and use it to give some insight on the shape of ϕs. Under suitable assumptions on π we are able to identify the optimal trajectory. We also find a non-linear Cauchy problem for the Cumulant Generating Function and provide an explicit analysis for some selected examples. In particular we discuss the linear case, which embeds the Bagchi–Pal Model [6], giving the exact implicit expression for ϕ in terms of the Cumulant Generating Function.

Cover Picture: Sodium Carboxymethylcellulose Derived Oxygen‐Rich Porous Carbon Anodes for High‐Performance Lithium/Sodium‐Ion Batteries (ChemElectroChem 3/2017)

The Front Cover picture shows the possibility of CMC (white balls) being used as a green binder in the anode of lithium-ion or sodium-ion batteries, employing an oxygen-containing carbon precursor to prepare oxygen-rich porous carbon (OPC, black-gray short rods), and then the carbon material can be used as the active material in the same anode. More information can be found in the Article by Y. Zhang et al. on page 500 in Issue 3, 2017 (DOI: 10.1002/celc.201600577).

The continuous-time triangular Pólya process

We study poissonized triangular (reducible) urns on two colors, which we take to be white and blue. We analyze the number of white and blue balls after a certain period of time has elapsed. We show that for balanced processes in this class, a different scaling is needed for each color to produce nontrivial limits, contrary to the distributions in the usual irreducible urns which only require the same scaling for both colors. The limit distributions (of the scaled variables) underlying triangular urns are Gamma. The technique we use couples partial differential equations with the method of moments applied in a bootstrapped manner to produce exact and asymptotic moments. For the dominant color, we get exact moments, while relaxing the balance condition. The exact moments include alternating signs and Stirling numbers of the second kind.

Trout Flashes

Trout Flashes Bill King (bio) 1. In the Blue Ridge mountains of southwestern Virginia, sitting on a rock that juts like a peninsula into a little stream called Back Creek, my twelve-year-old brother—wiry, already chiseled and lean—wets a piece of bread between the tip of his tongue and his front teeth, takes it out, balls it between his thumb and index finger, and then sticks [End Page 38] it on a hook. He throws it into the current at the top of the hole and lets it drift down and down. Maybe you'll catch a trout, I say. Ain't no trout in here, he says, pulling up another mad-tail-flipping sucker, a fat-headed thing with horny bumps on its crown. I want to fish, too, but there is never room for both of us. 2. An Irish tale tells of the forlorn young lover of a murdered prince, who, in drowning herself in a pristine mountain lake, transforms into a white trout. She is caught by an evil soldier, who cuts the white trout's side, releasing her bleeding human form. She bids the terrified soldier to throw her back in the little lake so that she can await her lover's return, which he does in great haste, bloodying the water and giving us the beautiful pink-streaked rainbow trout. In South Carolina, my uncle once told me to rub dirt, mud, and leaves on my hand to hide my human scent. Trout know, he said. They are the oldest and wisest fish you will ever catch. 3. There are rainbow trout, lake trout, cutthroat trout, brown trout, and tiger trout. The only trout native to West Virginia, though, is the brook trout. They live throughout Appalachia but only in the coldest and purist mountain streams. They sport a beautiful vermicular pattern—from dark green back, to bluish sides, to pink to scarlet belly—and interspersed throughout this swirling sky of color is a galaxy of yellow and red spots like stars behind a day-blind sky. No photograph can capture a brook trout's beauty. That's why, each spring—with pungent ramps greening the darkest hillsides and maple leaves still small and bright as babies' hands—I can't help but go for them. If I'm lucky, I'll get to cradle one in my palm—half in and half out of the water—before watching him slip beneath churning bubbles, which pour downstream like spilled pearls. [End Page 39] 4. Brook trout drop over fallen logs and shelving rock, into a deep and roiling hole, before settling in the shadow of a submerged boulder. Where they decide to stay, unless a fisher comes along and puts one in her creel, as heart-struck as a boy with a new ball. Mike Trout, the youngest in major league baseball history to hit 100 homeruns and steal 100 bases, smashes white balls with red stitching over fences throughout North America. They drop over walls like trout over a weir: into parking lots, under parked cars. And no one knows about them—ball or trout—when they step into their car, when they back out of wherever they are and head for highways at least two ridges removed from nowhere. 5. My 50-year-old friend Gordon loves to fish, but he acts like a boy when he catches a trout. Once we went up McGee run, which tumbles through the spruce, rhododendron and laurel of Cheat Mountain, before meeting the Shaver's Fork. It's hard to get there and you have to walk up the middle of the stream to navigate the tight confines of the holler. He put a picture of a brilliantly speckled 6-inch brookie on Facebook for his friends in Georgia to see. His face was flushed and red. His green eyes like stars sunk in a depthless pool. They made fun of his measly catch. You do not understand, he replied. 6. In Cormac McCarthy's post-apocalyptic novel, The Road, a father and son push a wobble-wheeled grocery cart down a broken road. They wend out of the Appalachians, through the...

A Markov chain with number-theoretic limit distribution

Abstract Let an urn contain balls of white and black colors. After each step with probabilities equal to 1 2 ${1 \over 2}$ either the number of white balls is increased by the number of black balls or the number of black balls is increased by the number of white balls. Formulas for the first two moments of the total number of balls in an urn are derived and it is shown that the limiting distribution function of the proportion of the number of white balls in an urn coincides with the Minkowski number-theoretic function.

Digenean trematode cysts within the heads of threatened Galaxiella species (Teleostei : Galaxiidae) from south-eastern Australia

The dwarf galaxias (Galaxiella pusilla) and little galaxias (Galaxiella toourtkoourt) are both threatened freshwater fish from south-eastern Australia. Occasionally populations have been found with enlarged heads associated with the accumulation of ‘white balls’, but the cause of these deformities has not previously been investigated. In this study, histopathology and molecular techniques were employed to identify cysts extracted from the heads of Galaxiella species across six populations. Histopathology and DNA sequences from both mitochondrial (cytochrome c oxidase subunit I) and nuclear (ribosomal internal transcribed spacer 1) regions identified the cysts as metacercariae of Apatemon gracilis (Rudolphi, 1819), a cosmopolitan digenean trematode species. Heavy infestations of trematode metacercariae within Galaxiella populations are of concern due to the potential to cause increased mortality associated with altered behaviour of the fish host that increases the likelihood of predation. Direct mortality from infestations is also possible, but not quantified in this study.

On the rate of convergence in de Finetti’s representation theorem

A consequence of de Finetti's representation theorem is that for every infinite sequence of exchangeable 0-1 random variables $(X_k)_{k\geq1}$, there exists a probability measure $\mu$ on the Borel sets of $[0,1]$ such that $\bar X_n = n^{-1} \sum_{i=1}^n X_i$ converges weakly to $\mu$. For a wide class of probability measures $\mu$ having smooth density on $(0,1)$, we give bounds of order $1/n$ with explicit constants for the Wasserstein distance between the law of $\bar X_n$ and $\mu$. This extends a recent result {by} Goldstein and Reinert \cite{goldstein2013stein} regarding the distance between the scaled number of white balls drawn in a P\'olya-Eggenberger urn and its limiting distribution. We prove also that, in the most general cases, the distance between the law of $\bar X_n$ and $\mu$ is bounded below by $1/n$ and above by $1/\sqrt{n}$ (up to some multiplicative constants). For every $\delta \in [1/2,1]$, we give an example of an exchangeable sequence such that this distance is of order $1/n^\delta$.

Could Computer Game Players React as Quick as Table Tennis Athletes and Perform the Right Action?

Objective: Table tennis athletes have short reaction times and specialized skills. Computer games may also decrease reaction times. However the actions of the computer game players are limited to mouse/keyboard/joystick use. The objective of the study is to compare the reaction times and the achievement levels on selective action array of athletes and players. Material and Methods: 10 medical school students that played computer games 10 hours a week for at least 5 years, and 9 table tennis athletes that were trained 10 hours a week for at least 5 years were included in the study. Right/left-hand/foot reaction times against auditory and visual stimuli were recorded for each subject. Selective action array was implemented utilizing a table tennis robot. The robot was set up to send 120 balls in different colors, to different points on the table, in random colors and 90 balls per minute at the same speed. The subjects were asked to ignore the white balls, to touch the yellow balls and to hold the pink balls. The actions that the subjects took, or did not take against each ball were transformed into points. Results: It was found that the mean reaction time for athletes was 196.8ms and 196.0ms for the players. The selective action array total points were similar in athletes and players. While the athletes scored better with yellow and pink balls, players scored better with the white balls. Conclusion: The similar scores and reaction times by players and athletes could be interpreted that it could be beneficial to prioritize visual perception, attention and focusing in selecting athletes and in designing training programs.