Sociotechnical constituencies, game theory, and the diffusion of compact discs. An inter-disciplinary investigation into the market for recorded music

This article was motivated by the inquiry of the National Heritage Committee of the British House of Commons into the price of compact discs in 1993. Its general thrust is to foster the dialogue between sociological approaches to the study of innovation and microeconomic theory. To do this, it presents a comprehensive case study of technological innovation in the market for recorded music in Britain. The material is analysed with the aid of the ‘sociotechnical constituencies’ approach recently proposed in this journal by Alfonso Molina, followed by a game theoretical analysis of competitive alignment between the dominant constituents. Using this interdisciplinary approach, the article argues that technological innovation may induce price rigidities by allowing the establishment of focal points for tacit collusion. The innovation of compact discs enabled the major record companies to redefine the overall price level to their advantage, after the industry had undergone a period of profit-squeezing price-competition. This has the important policy implication that radical product innovation may call for regulative changes in the techno-institutional structure of the market.     

Plasticity of human handedness: decreased one-hand bias and inter-manual performance asymmetry in expert basketball players

Athletes frequently have to adapt their skills to fast changes of play, often requiring the flexible execution of a particular movement skill with either hand. To assess the influence of sport-specific expertise and extensive sport training on human laterality, a video analysis of regular basketball games was performed for professional, semi-professional, and amateur players to investigate how non-dominant hand use and proficiency change with increasing expertise. Our results showed that the right-hand (i.e. dominant hand) bias in basketball players is reduced with increasing expertise (i.e., competitive level). Accordingly, we found that professional players use their non-dominant hand more often and with greater success than semi-professional and amateur players. This was true for most of the basketball-specific skills. Based on these results, we assume that increasing amounts of bilateral practice can lead to a shift in task-specific manual preference towards a higher use of both hands in competition, as well as to a higher proficiency for non-dominant hand actions in particular. From an applied perspective, the more frequent use and higher proficiency of the non-dominant hand in professional basketball players, compared with amateurs, suggests that the context-specific and skilled use of the non-dominant hand is crucial for successful play at higher competitive levels in the sport of basketball.     

Different types of compression clothing do not increase sub-maximal and maximal endurance performance in well-trained athletes

Abstract

Three textiles with increasing compressive surface were compared with non-compressive conventional clothing on physiological and perceptual variables during sub-maximal and maximal running. Fifteen well-trained endurance athletes (mean ± s: age 27.1 ± 4.8 years, [Vdot]O_2max 63.7 ± 4.9 ml · min^?1 · kg^?1) performed four sub-maximal (～70%[Vdot]O_2max) and maximal tests with and without different compression stockings, tights, and whole-body compression suits. Arterial lactate concentration, oxygen saturation and partial pressure, pH, oxygen uptake, and ratings of muscle soreness were recorded before, during, and after all tests. In addition, we assessed time to exhaustion. Sub-maximal (P = 0.22) and maximal oxygen uptake (P = 0.26), arterial lactate concentration (P = 0.16; 0.20), pH (P = 0.23; 0.46), oxygen saturation (P = 0.13; 0.26), and oxygen partial pressure (P = 0.09; 0.20) did not differ between the types of clothing (effect sizes = 0.00–0.45). Ratings of perceived exertion (P = 0.10; 0.15), muscle soreness (P = 0.09; 0.10) and time to exhaustion (P = 0.16) were also unaffected by the different clothing (effect sizes = 0.28–0.85). This was the first study to evaluate the effect on endurance performance of different types of compression clothing with increasing amounts of compressive surface. Overall, there were no performance benefits when using the compression garments.     

The dilemma of dealing with persistent teaching traditions: findings of a video study

Nowadays, there is a consensus that good teaching and learning needs instructional variation and personalised forms of learning. In teacher education, these concepts have been implemented for years, and prospective teachers are taught accordingly; it is thus assumed that the teaching of novice teachers is in accordance with these new teaching concepts. In the research project ‘ALPHA’, the teaching of novice teachers at the beginning and at the end of their first year in the profession and the teaching of experienced teachers with five or more years of teaching experience was videotaped, so that longitudinal and cross-sectional comparisons were possible. The lessons were analysed by applying a coding system on the instruction and by employing a rater inventory in order to understand the structure and quality of the lessons. Overall, the results indicate high levels of whole class teaching with a rather high level of traditional classroom instruction both for the novice and the experienced teachers. However, the proportions vary depending on the location of teacher education. The results provide evidence that the new teaching concepts learned on the teacher education programme are not necessarily implemented in the classroom and provide possible reasons why this might be the case.     

University physics students’ ideas of thermal radiation expressed in open laboratory activities using infrared cameras

Background: University physics students were engaged in open-ended thermodynamics laboratory activities with a focus on understanding a chosen phenomenon or the principle of laboratory apparatus, such as thermal radiation and a heat pump. Students had access to handheld infrared (IR) cameras for their investigations.

Purpose: The purpose of the research was to explore students’ interactions with reformed thermodynamics laboratory activities. It was guided by the research question: How do university physics students make use of IR cameras in open-ended investigation of thermal radiation as a phenomenon?

Sample: The study was conducted with a class of first-year university physics students in Sweden. The interaction with the activities of four of the students was selected for analysis. The four students are males.

Design and methods: We used a qualitative, interpretive approach to the study of students’ interaction. The primary means of data collection was video recording of students’ work with the laboratory activities and their subsequent presentations. The analysis focused on how IR cameras helped students notice phenomena relating to thermal radiation, with comparison to previous research on students’ conceptions of thermal radiation.

Results: When using the IR camera, students attended to the reflection of thermal radiation on shiny surfaces, such as polished metals, windows or a whiteboard and emissive properties of surfaces of different types. In this way, they went beyond using the technology as a temperature probe. Students were able to discuss merits and shortcomings of IR cameras in comparison with digital thermometers.

Conclusions: With the help of IR cameras, university physics students attend to thermal phenomena that would otherwise easily go unnoticed.     

Efficient reverse k-nearest neighbor estimation

The reverse k-nearest neighbor (RkNN) problem, i.e. finding all objects in a data set the k-nearest neighbors of which include a specified query object, has received increasing attention recently. Many industrial and scientific applications call for solutions of the RkNN problem in arbitrary metric spaces where the data objects are not Euclidean and only a metric distance function is given for specifying object similarity. Usually, these applications need a solution for the generalized problem where the value of k is not known in advance and may change from query to query. In addition, many applications require a fast approximate answer of RkNN-queries. For these scenarios, it is important to generate a fast answer with high recall. In this paper, we propose the first approach for efficient approximative RkNN search in arbitrary metric spaces where the value of k is specified at query time. Our approach uses the advantages of existing metric index structures but proposes to use an approximation of the nearest-neighbor-distances in order to prune the search space. We show that our method scales significantly better than existing non-approximative approaches while producing an approximation of the true query result with a high recall.     

Successful Aging through Television: Selective and Compensatory Television Use and Well-Being

ABSTRACT

We applied the selection, optimization and compensation (SOC) model of successful aging to media use. Using a new self-report measure to assess selective and compensatory media use we illustrate the role of these media selection strategies in successful aging. In other words, we link compensatory and selective media use to different indicators of well-being among older nursing home residents and for a group of younger adults, which served as a comparison group. Selective media use was positively related to well-being for older, but not for younger adults, and compensatory media use was negatively related to well-being for both younger and older adults. In a second study, we replicated these findings with a sample of healthy older adults.     

中德学生数学建模能力水平的比较分析——以中国上海和德国巴登符腾堡州学生为例

近期参照的数学建模能力水平分析框架,对中国上海以及德国巴州的一千余名9～11年级学生进行实验研究.结果表明,中德学生的数学建模能力的平均水平非常接近,但是从各个不同的能力水平看,两国学生的成绩存在着一定的差异;另外发现学生的数学建模能力随着年级的升高也不断发展.透过结果发现,中学生数学建模能力薄弱,上海学生的基本技能有滑坡倾向;另外需把握开展数学建模教学的最佳时机.     

Das MINERVA-Projekt: Datenbankselektion für Peer-to-Peer-Websuche

In diesem Artikel wird MINERVA pr?sentiert, eine prototypische Implementierung einer verteilten Suchmaschine basierend auf einer Peer-to-Peer (P2P)-Architektur. MINERVA setzt auf die in der P2P-Welt verbreitete Technik verteilter Hash-Tabellen auf und benutzt diese zum Aufbau eines verteilten Verzeichnisses. Peers in unserem Ansatz entsprechen v?llig autonomen Benutzern mit ihren lokalen Suchm"oglichkeiten, die bereit sind, ihr lokales Wissen und ihre lokalen Suchm?glichkeiten im Rahmen einer Kollaboration zur Verfügung zu stellen. Wir formalisieren unsere Systemarchitektur und beschreiben das zentrale Problem einer effizienten Suche nach vielversprechenden Peers für eine konkrete Anfrage innerhalb des Verbundes. Wir greifen dabei auf existierende Methoden zurück and passen diese an unseren Systemkontext an. Wir pr?sentieren Experimente auf realen Daten, die verschiedene dieser Ans?tze vergleichen. Diese Experimente zeigen, dass die Qualit?t der Ans?tze variiert und untermauern damit die Wichtigkeit und den Einfluss einer leistungsstarken Methode zur Auswahl guter Datenbanken. Unsere Experimente deuten an, dass eine geringe Anzahl sorgf?ltig ausgew?hlter Datenbanken typischerweise bereits einen Gro?teil aller relevanten Ergebnisse des Gesamtsystems liefert.     

The Online Market for Illegal Copies of Magazines: A German Case Study

A few years ago, publishing companies started to sell digital copies of their magazines. This study investigates a consequence of this change: the increasing online trade with illegal copies. We collected data on almost 10,000 issues of German magazines that are illegally offered online. The files are distributed in a three-sided market, in which a small number of platforms bring suppliers of illegal copies, consumers, and advertisers together. The market has been growing rapidly—between 2009 and 2012 by a factor of 10. In contrast to the legal magazine market, the illegal trade mostly concerns IT and consumer electronics magazines.