Efficient online index maintenance for contiguous inverted lists

Search engines and other text retrieval systems use high-performance inverted indexes to provide efficient text query evaluation. Algorithms for fast query evaluation and index construction are well-known, but relatively little has been published concerning update. In this paper, we experimentally evaluate the two main alternative strategies for index maintenance in the presence of insertions, with the constraint that inverted lists remain contiguous on disk for fast query evaluation. The in-place and re-merge strategies are benchmarked against the baseline of a complete re-build. Our experiments with large volumes of web data show that re-merge is the fastest approach if large buffers are available, but that even a simple implementation of in-place update is suitable when the rate of insertion is low or memory buffer size is limited. We also show that with careful design of aspects of implementation such as free-space management, in-place update can be improved by around an order of magnitude over a naïve implementation.     

Fertility or sterility? Darwin,Naudin and the problem of experimental hybridity

Darwin came to realize that he could never devise an experiment that would demonstrate the development of new species by crossing hybrids. Instead, he turned to the problem of sterility within a species. The difference between Darwin's experimental and theoretical approach and that of French scientists working in the Muséum d'Histoire Naturelle in Paris can be shown most vividly by tracking Darwin's experiments in botany and his interest in those of Charles Naudin on hybrid plants. In his discussion of Mendel, Robert Olby has provided an interesting analysis of Naudin's hereditary concepts. I have approached some of the same work here with an emphasis on the question of sterility raised by Darwin, not simply between hybrids but within members of the same species and the light that he thought this could throw on both heredity and the origin of species.     

An online adaptive learning environment for critical‐thinking‐infused English literacy instruction

Critical thinking (CT) and English literacy are two essential 21st century competencies that are a priority for teaching and learning in an increasingly digital learning environment. Taking advantage of innovations in educational technology, this study empirically investigates the effectiveness of CT‐infused adaptive English literacy instruction using a Moodle system. A one‐group pretest–posttest design was employed to evaluate the effect of the treatment on students' acquisition of CT skills (CTS) and English literacy. A total of 83 students enrolled in two sections of a general studies course at a large university in Taiwan participated in the semester‐long experiment. Adaptive learning was achieved through the use of an online Moodle system for (1) online grouping (based on pretest English literacy scores), (2) delivery of specifically designed adaptive learning materials for each group and (3) provision of individualised feedback. CT‐infused language activities based on social constructivist principles were designed for each level of adaptive instruction, whereas direct instruction for fostering CTS was provided in class and practiced or reflected upon in groups. Empirical results demonstrate that CT‐enhanced adaptive English literacy instruction simultaneously improved students' CTS and English literacy and that students' online discussions developed towards higher levels of interaction. This paper illustrates an effective blended learning model for adaptive instruction and offers recommendations for designing CT‐infused language learning activities that can successfully foster both CT and English literacy outcomes.     

‘To Give an Example is a Complex Act’: Agamben’s pedagogy of the paradigm

Abstract

Agamben’s notion of the ‘paradigm’ has far-reaching implications for educational thinking, curriculum design and pedagogical conduct. In his approach, examples—or paradigms—deeply engage our powers of analogy, enabling us to discern previously unseen affinities among singular objects by stepping outside established systems of classification. In this way we come to envision novel groupings, new patterns of connection—that nonetheless do not simply reassemble those singular objects into yet another rigidly fixed set or class. Agamben sees this sort of ‘paradigmatic understanding’ as our richest source of intelligibility. For Agamben the paradigm is ultimately about learning to see again, starting not with already perfectly known and categorized objects (or ideas), but rather with a fresh experience of one individual object and the analogical relations it may have to others, and to novel groupings that may arise. The paradigm is a method, a way in which educators might respond to a wide range of educational challenges. For a paradigmatic relation suspends while exposing, deactivates while revealing, complicates while clarifying. But articulating the enigmatic paradigmatic relation between example and class is far more than a method. It is epistemological (a way of knowing and conception of knowledge), ethical (a fostering of freedom from presupposed categories and reified principles) and ontological (a type of being that exposes the potential of knowing and communicating—their intelligibility and communicability). In these qualities, paradigms exhibit to educators a free, a new use of singularities.     

WHAT IS INTERIORITY AND WHY MIGHT IT BE IMPORTANT FOR HUMAN PERFORMANCE TECHNOLOGY?

Considerations of the inner world of workers and organizations might not fall within the provenance of human performance technology (HPT) practitioners. However, when it comes to being creative, workers need fertile imaginations driven from within. When it comes to productivity, mostly inner energies drive collaboration. When it comes to results, leaders must nurture workers toward wholeness for effective decisions and wisdom‐driven action. For these reasons, HPT practitioners need to know how to engage with the interiority factor.     

Pre-service physical education teachers' beliefs about competition in physical education

The discourse of competitive sport is, and has been, a defining feature of physical education for many years. Given the privileged and dominant position competition holds in physical education curricula, it is concerning that competitive physical education remains steeped in traditional pedagogies and that these pedagogies are constrained by teachers' everyday philosophies rather than any explicit understanding of pedagogy or the needs of pupils. This in turn affects pupils' experiences of physical education and specifically the type and form of activities that are offered to pupils. Physical education teachers' biographies generally show a profound attachment to sport, and in particular competitive sport, and the value of competitive sport is significant in the lives and identities of physical education recruits. However, there is a paucity of research specifically in relation to in-service and pre-service physical education teacher's beliefs about competition and its place in physical education. It is well documented that the implicit theories that pre-service, beginning and experienced teachers hold influence their reactions to teacher education and their teaching practice, with their beliefs acting as a filter through which a host of instructional judgements and decisions are made. Thus, it is important to understand pre-service physical education teachers' (PSTs') beliefs about competition. Thirty five (16 men, 15 women, 4 unknown) PSTs completed a reflective journal alongside their participation in a University-based module focused on models-based practice. The data generated were analysed using the procedures and techniques of grounded theory which revealed five major themes grouped in the discussion under the sub-categories of: (1) defining competition; (2) learning through competition; (3) competitive physical education and the sporting pathway; (4) competition needs to be got out of children; and (5) a little competition. The discussion challenges how we transform traditional views of competition and the competitive practices that alienate some young people from physical education.     

Home advantage in southern hemisphere rugby union: Nationaland international

Abstract

This study evaluates home advantages both for national (Super 12) and international (Tri-nations) rugby union teams from South Africa, Australia and New Zealand, over the five-year period 2000 – 2004 using linear modelling. These home advantages are examined for statistical and practical significance, for variability between teams, for stability over time and for inter-correlation. These data reveal that the overall home advantage in elite rugby union has a mean of +6.7 points, and that this changes little from year to year. Closer scrutiny nevertheless reveals a high degree of variability. Different teams can and do have different home advantages, which ranges from a low of ?0.7 to a high of +28.3 points in any one year. Furthermore, some team home advantages change up or down from one year to the next, by as much as ?36.5 to +31.4 points at the extremes. There is no evidence that the stronger teams have the higher home advantages, or that a high home advantage leads to a superior finishing position in the competition.     

The effect of induced alkalosis and submaximal cycling on neuromuscular response during sustained isometric contraction

Abstract

The aim of this study was to determine if inducing metabolic alkalosis would alter neuromuscular control after 50 min of standardized submaximal cycling. Eight trained male cyclists (mean age 32 years, s = 7; [Vdot]O_2max 62 ml · kg^?1 · min^?1, s = 8) ingested capsules containing either CaCO₃ (placebo) or NaHCO₃ (0.3 g · kg^?1 body mass) in eight doses over 2 h on two separate occasions, commencing 3 h before exercise. Participants performed three maximal isometric voluntary contractions (MVC) of the knee extensors while determining the central activation ratio by superimposing electrical stimulation both pre-ingestion and post-exercise, followed by a 50-s sustained maximal contraction in which force, EMG amplitude, and muscle fibre conduction velocity were assessed. Plasma pH, blood base excess, and plasma HCO₃ were higher (P < 0.01) during the NaHCO₃ trial. After cycling, muscle fibre conduction velocity was higher (P < 0.05) during the 50-s sustained maximal contraction with NaHCO₃ than with placebo (5.1 m · s^?1, s = 0.4 vs. 4.2 m · s^?1, s = 0.4) while the EMG amplitude remained the same. Force decline rate was less (P < 0.05) during alkalosis-sustained maximal contraction and no differences were shown in central activation ratio. These data indicate that induced metabolic alkalosis can increase muscle fibre conduction velocity following prolonged submaximal cycling.     

Genetic research and testing in sport and exercise science: A review of the issues

Abstract

This review is based on the BASES position stand on “Genetic Research and Testing in Sport and Exercise Science”. Our aims are first to introduce the reader to research in sport and exercise genetics and then to highlight ethical problems arising from such research and its applications. Sport and exercise genetics research in the form of transgenic animal and human association studies has contributed significantly to our understanding of exercise physiology and there is potential for major new discoveries. Researchers starting out in this field will have to ensure an appropriate study design to avoid, for example, statistically underpowered studies. Ethical concerns arise more from the applications of genetic research than from the research itself, which is assessed by ethical committees. Possible applications of genetic research are genetic performance tests or genetic tests to screen, for example, for increased risk of sudden death during sport. The concerns are that genetic performance testing could be performed on embryos and could be used to select embryos for transplantation or abortion. Screening for risk of sudden death may reduce deaths during sporting events but those that receive a positive diagnosis may suffer severe psychological consequences. Equally, it will be almost impossible to keep a positive diagnosis confidential if the individual tested is an elite athlete.     

Sand training: a review of current research and practical applications

Abstract

Sand surfaces can offer a higher energy cost (EC) and lower impact training stimulus compared with firmer and more traditional team sport training venues such as grass. This review aims to summarise the existing research on sand training, with a specific focus on its application as a team sports training venue. Compared with grass, significant physiological and biomechanical differences are associated with sand exercise. However, evidence also exists to suggest that training adaptations unique to sand can positively influence firm-ground performance. Furthermore, the lower impact forces experienced on sand can limit muscle damage, muscle soreness, and decrements in performance capacity relative to exercise intensity. Therefore, using a sand training surface in team sports may allow greater training adaptations to be achieved, while reducing performance decrements and injuries that may arise from heavy training. Nevertheless, further research should investigate the effect of sand surfaces over a greater range of training types and performance outcomes, to increase the application of sand training for team sports.