Detecting sequential structure

Programming by demonstration requires detection and analysis of sequential patterns in a user’s input, and the synthesis of an appropriate structural model that can be used for prediction. This paper describes SEQUITUR, a scheme for inducing a structural description of a sequence from a single example. SEQUITUR integrates several different inference techniques: identification of lexical subsequences or vocabulary elements, hierarchical structuring of such subsequences, identification of elements that have equivalent usage patterns, inference of programming constructs such as looping and branching, generalisation by unifying grammar rules, and the detection of procedural substructure., Although SEQUITUR operates with abstract sequences, a number of concrete illustrations are provided

Online and offline heuristics for inferring hierarchies of repetitions in sequences

Hierarchical dictionary-based compression schemes form a grammar for a text by replacing each repeated string with a production rule. While such schemes usually operate online, making a replacement as soon as repetition is detected, offline operation permits greater freedom in choosing the order of replacement. In this paper, we compare the online method with three offline heuristics for selecting the next substring to replace: longest string first, most common string first, and the string that minimized the size of the grammar locally. Surprisingly, two of the offline techniques, like the online method, run in time linear in the size of the input. We evaluate each technique on artificial and natural sequences. In general, the locally-most-compressive heuristic performs best, followed by most frequent, the online technique, and, lagging by some distance, the longest-first technique

The reliability and validity of a field hockey skill test

High test retest reliability is essential in tests used for both scientific research and to monitor athletic performance. Thirty-nine (20 male and 19 female) well-trained university field hockey players volunteered to participate in the study. The reliability of the in house designed test was determined by repeating the test (3-14 days later) following full familiarisation. The validity was assessed by comparing coaches ranks of players with ranked performance on the skill test. The mean difference and confidence limits in overall skill test performance was 0.0 ± 1.0% and the standard error (confidence limits) was 2.1% (1.7 to 2.8%). The mean difference and confidence limits for the ‘decision making’ time was 0.0 ± 1.0% and the standard error (confidence limits) was 4.5% (3.6 to 6.2%). The validity correlation (Pearson) was r = 0.83 and r= 0.73 for female players and r = 0.61 and r = 0.70 for male players for overall time and ‘decision making’ time respectively. We conclude that the field hockey skill test is a reliable measure of skill performance and that it is valid as a predictor of coach assessed hockey performance, but the validity is greater for female players

Extracting text from PostScript

We show how to extract plain text from PostScript files. A textual scan is inadequate because PostScript interpreters can generate characters on the page that do not appear in the source file. Furthermore, word and line breaks are implicit in the graphical rendition, and must be inferred from the positioning of word fragments. We present a robust technique for extracting text and recognizing words and paragraphs. The method uses a standard PostScript interpreter but redefines several PostScript operators, and simple heuristics are employed to locate word and line breaks. The scheme has been used to create a full-text index, and plain-text versions, of 40,000 technical reports (34 Gbyte of PostScript). Other text-extraction systems are reviewed: none offer the same combination of robustness and simplicity

Can greater muscularity in larger individuals resolve the 3/4 power-law controversy when modelling maximum oxygen uptake?

BACKGROUND: The power function relationship, MR = a.m(b), between metabolic rate (MR) and body mass m has been the source of much controversy amongst biologists for many years. Various studies have reported mass exponents (b) greater than the anticipated 'surface-area' exponent 0.67, often closer to 0.75 originally identified by Kleiber. AIM: The study aimed to provide a biological explanation for these 'inflated' exponents when modelling maximum oxygen uptake (max), based on the observations from this and previous studies that larger individuals develop disproportionately more muscle mass in the arms and legs. RESEARCH DESIGN AND SUBJECTS: A cross-sectional study of 119 professional soccer players from Croatia aged 18-34 was carried out. RESULTS: Here we confirm that the power function relationship between max and body mass of the professional soccer players results in an 'inflated' mass exponent of 0.75 (95% confidence interval from 0.56 to 0.93), but also the larger soccer players have disproportionately greater leg muscle girths. When the analysis was repeated incorporating the calf and thigh muscle girths rather than body mass as predictor variables, the analysis not only explained significantly more of the variance in max, but the sum of the exponents confirmed a surface-area law. CONCLUSIONS: These findings confirm the pitfalls of fitting body-mass power laws and suggest using muscle-girth methodology as a more appropriate way to scale or normalize metabolic variables such as max for individuals of different body sizes

Influence of biological maturity on the match performance of 8 to 16 year old elite male youth soccer players

The aim of this study was to examine the influence of biological maturity on match performance in elite youth male soccer players. The participants were 80 Premier League Academy outfield players (8-16 years old). Biological maturity was determined by calculating estimated chronological age at peak height velocity. The U9 and U10 squads played 6-a-side and the U11-U16 squads played 11-a-side inter-academy matches. All matches were analyzed using a 1 Hz Global Positioning System (SPI elite, GPSport, Australia) with squad specific speed zones which were calculated based on 5 m flying sprint speed in the last 5 m of 10 m sprint test. In the U9/U10s, earlier maturers were given a longer pitch time by coaches (~4 min per match, p = 0.029) and covered a greater total distance (~9%, ~400 m, p = 0.037) and a greater distance by walking (~13%, ~100 m, p = 0.024) and jogging (~12%, ~200 m, p = 0.014) during a match compared to later maturers. In the U13/U14s, earlier maturers covered a greater distance per hour of a match by high speed running compared to later maturers (~25%, ~130 m, p = 0.028) and spent a longer percentage of time in high speed running during a match compared to later maturers (3.4% vs. 2.7%, p = 0.034). Thus, coaches should take care to provide all players with a similar pitch-time and should be aware in the talent identification and development process, particularly with the U13/U14 age group, that maturity can influence high speed match running performance

Match Analysis of U9 and U10 English Premier League Academy Soccer Players Using a Global Positioning System

The purpose of this study was to examine the match activity profile of U9 and U10 elite soccer players and to establish if there were any differences between players who were subsequently retained or released by their clubs. Such information should prove valuable in the design of training programs for these very young players and in the talent identification and development process. A Global Positioning System was used to analyze 2-4 inter-academy 6-a-side matches of English Premier League Academy players (U9: N=22 and U10: N=12) who trained three times a week (4.5 h). Speed zones were created based on 5 and 10m sprint times and an independent sample t-test was employed for a statistical analysis. Both squads covered ~4000 m in total or ~4700 m·h-1 during a match (NS between squads), with the U10s tending to cover a greater distance at moderate (p = 0.10) and high speeds (p=0.08) than the U9s. Retained group covered a greater distance than released group (retained vs. released: 4478±513 m vs. 4091±462 m, p<0.05) during a match and covered a greater distance during low speed running in absolute (1226±259 m vs. 1005±221 m, p<0.05) and relative (1325±235 m·h-1 vs. 1132±210 m·h-1, p<0.05) terms. Thus, U9 and U10 players cover over 4000 m in match play and those players who are retained by academies cover a greater distance in total and at low speeds (2.1-3.1 m·s-1). This information may support the preparation of squad training programs and the talent identification and development process

Record Litter Size for the Bull Shark, Carcharhinus leucas (Muller & Henle, 1839), documented in the Seychelles

On the morning of 25 September 2013, a large female bull shark, Carcharhinus leucas, was landed in Port Victoria, Seychelles. It had been caught on an anchored long line set the previous evening, within 100 m of the main fishing quay. The female exhibited an unusually large girth for this heavy-set species. The shark was photographed (Fig. 1a) and morphological measurements taken. On dissection the shark was found to be carrying 14 late stage embryos which were likewise measured and photographed (Fig. 1b).  The adult female measured 276 cm total length (TL). The 14 pups, consisting of seven males and seven females, had a mean TL of 69 cm and a size range of 65-71cm TL. The pups’ teeth had yet to emerge from the gums suggesting parturition was not imminent. Leading international data sources, Fishbase (Froese &amp; Pauly, 2013) and the IUCN Red List (Simpfendorfer &amp; Burgess, 2009), cite the maximum litter size for C. leucas as 13 pups. Review of the authoritative compendia and literature that inform these databases (Bass et al., 1973, Garrick, 1982, Compagno, 1984, Fowler et al., 2005) confirmed this maximum litter size but indicated that the majority of litters number between 6-8 pups. Furthermore, the upper limit of 13 pups comes from a single reference (Bass et al., 1973) that was not categoric, but stated that the litter in question contained “either 12 or 13 pups”. This Seychelles record therefore constitutes a definitive new finding for C. leucas, extending the known parameters of its reproductive capacity.