Level of deprivation does not affect degree of discounting in pigeons

Two experiments tested the effects of food deprivation on discounting in pigeons. An adjusting-amount procedure was used to estimate the subjective value of food at delays ranging from 1 to 24 s. Experiment 1 compared pigeons’ discounting of delayed food reinforcers at 75 %–80 % and 90 %–95 % of free-feeding weight. Experiment 2 compared discounting under 1- and 23-h food deprivation. In both experiments at both deprivation levels, discounting was well described by the hyperboloid discounting function. No systematic effect of level of deprivation on degree of discounting was observed in either experiment. This finding is consistent with the view that pigeons’ choices are controlled by the relative, rather than the absolute, value of reinforcers.     

Implicit indexing of natural language text by reorganizing bytecodes

Word-based byte-oriented compression has succeeded on large natural language text databases, by providing competitive compression ratios, fast random access, and direct sequential searching. We show that by just rearranging the target symbols of the compressed text into a tree-shaped structure, and using negligible additional space, we obtain a new implicitly indexed representation of the compressed text, where search times are drastically improved. The occurrences of a word can be listed directly, without any text scanning, and in general any inverted-index-like capability, such as efficient phrase searches, can be emulated without storing any inverted list information. We experimentally show that our proposal performs not only much more efficiently than sequential searches over compressed text, but also than explicit inverted indexes and other types of indexes, when using little extra space. Our representation is especially successful when searching for single words and short phrases.     

International trends in health science librarianship: Part 4 – Four Southern European countries

This is the fourth in a series of articles exploring international trends in health science librarianship in four Southern European countries in the first decade of the 21st century. The invited authors are from Greece, Italy, Spain and Portugal. Future issues will track trends in Latin America and Central Europe. JM     

Toward a Longitudinal Model of e-Commerce: Environmental,Technological, and Organizational Drivers of B2C Adoption

Despite the important benefits for firms of commercial initiatives on the Internet, e-commerce is still an emerging distribution channel, even in developed countries. Thus, more needs to be known about the mechanisms affecting its development. A large number of works have studied firms' e-commerce adoption from technological, intraorganizational, institutional, or other specific perspectives, but there is a need for adequately tested integrative frameworks. Hence, this work proposes and tests a model of firms' business-to-consumer (called B2C) e-commerce adoption that is founded on a holistic vision of the phenomenon. With this integrative approach, the authors analyze the joint influence of environmental, technological, and organizational factors; moreover, they evaluate this effect over time. Using various representative Spanish data sets covering the period 1996–2005, the findings demonstrate the suitability of the holistic framework. Likewise, some lessons are learned from the analysis of the key building blocks. In particular, the current study provides evidence for the debate about the effect of competitive pressure, since the findings show that competitive pressure disincentivizes e-commerce adoption in the long term. The results also show that the development or enrichment of the consumers' consumption patterns, the technological readiness of the market forces, the firm's global scope, and its competences in innovation continuously favor e-commerce adoption.     

Spatial-temporal constraints on decision-making during shooting performance in the team sport of futsal

Abstract

In this paper we examined the influence of opposing players constraining the decision-making of an attacker during shooting performance in futsal. Performance during 10 competitive matches was recorded and examined from the moment a shot was taken until the ball was intercepted or entered the goal in sequences of play: ending in a goal, a goalkeeper's save, or an interception by the nearest defender. The variables under scrutiny in this study were (i) the distance of each player to the ball's trajectory, (ii) the time for the ball to arrive at that same point (i.e. the interception point), and (iii), the required movement velocity of the nearest defender and the goalkeeper to intercept the ball. Results showed that values of distance from a defender and goalkeeper to the interception points were significantly lower when they intercepted the ball. The time of ball arrival at the interception point of the defender was also lower when the ball was intercepted. The required velocities of the nearest outfield defender and the goalkeeper to intercept the ball were significantly lower during plays in which they intercepted the ball, than in plays in which the ball was not intercepted. Our results suggest that researchers and practitioners should consider simultaneously both space and time in analysis of interceptive actions in team sports. The required movement velocities of the opponents to intercept the ball are reliable spatial-temporal variables constraining decision-making during shooting performance in team sports like futsal.     

The effects of verbal encouragement and conscientiousness on maximal voluntary contraction of the triceps surae muscle in elite athletes

Abstract

We investigated the effect of verbal encouragement on maximal voluntary contraction (MVC) level of the triceps surae muscle group. Our secondary focus was to examine whether the effect of verbal encouragement on MVC level varies as a result of conscientiousness. While the participants performed plantar flexion, MVCs of the triceps surae muscle group were measured using rectified and smoothed surface electromyography (rsEMG) during the absence and presence of verbal encouragement. Participants completed questions from the Five Factor Personality Inventory concerning conscientiousness and were divided into high- and low-conscientiousness groups according to a median split. The sample included 30 female and 53 male elite athletes. In the entire cohort, there was no significant difference in MVCs with and without verbal encouragement. When the sample was partitioned by conscientiousness scores, verbal encouragement led to a significant increase in MVC in the low-conscientiousness group, whereas verbal encouragement led to a non-significant decrease in MVC in the high-conscientiousness group. Percentage change in MVC across experimental conditions was significantly different between the groups, with a 9.72% increase during verbal encouragement of the low-conscientiousness group, and a 2.47% decrease during verbal encouragement of the high-conscientiousness group.