Defining the problem: key element for the success of knowledge management

The objective of this paper is to propose a methodology for applying knowledge management (KM), in which we first focus on explaining problematic areas of an organization by identifying the knowledge core process, before applying KM strategies to those processes. For the methodology, we lean on the larger context of systems thinking to help visualize the whole organization, and it is here that the key factors are identified and a set of strategic criteria is established. The most important criteria are then used to evaluate the associated processes and their respective tasks in order to establish the problematic areas or opportunities where KM initiatives can be applied. This strategy precludes tackling all the organization's problems and allows management to focus on only those processes that provide significant and manageable knowledge. Finally, this study explores and cautiously recommends an unexploited but valuable element to be taken into account when implementing KM initiatives.     

Aerobic fitness and academic achievement: A systematic review and meta-analysis

ABSTRACT

This study aims to quantify the association between aerobic fitness and academic achievement, and determine how different aerobic fitness tests and individual demographic characteristics may modify this association. It includes 41 cross-sectional and 7 longitudinal studies focusing on children and adolescents, from MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database and Web of Science. Pooled effect sizes (ES) were estimated for the association between aerobic fitness and specific domains of academic achievement. Subgroup analyses and meta-regressions were based on aerobic fitness tests and demographic characteristics. The ES for the association between aerobic fitness with language/reading-skills, mathematics-related skills and composite scores, were 0.23 (95% CI: 0.12; 0.34); 0.27 (95% CI: 0.19; 0.36) and 0.28 (95% CI: 0.12; 0.45), respectively. Subgroup analyses by aerobic fitness test modified these associations; additionally, analyses by sex or age showed differences between boys and girls as well as between children and adolescents. Finally, meta-regressions revealed a slight effect of body mass index on these associations. Cardiorespiratory fitness is positively associated with academic achievement. Associations were dependent on demographic and aerobic fitness test characteristics, being stronger in boys than in girls, and in children than in adolescents.

Systematic review registration: PROSPERO CRD42017069677     

Statistical biases in Information Retrieval metrics for recommender systems

There is an increasing consensus in the Recommender Systems community that the dominant error-based evaluation metrics are insufficient, and mostly inadequate, to properly assess the practical effectiveness of recommendations. Seeking to evaluate recommendation rankings—which largely determine the effective accuracy in matching user needs—rather than predicted rating values, Information Retrieval metrics have started to be applied for the evaluation of recommender systems. In this paper we analyse the main issues and potential divergences in the application of Information Retrieval methodologies to recommender system evaluation, and provide a systematic characterisation of experimental design alternatives for this adaptation. We lay out an experimental configuration framework upon which we identify and analyse specific statistical biases arising in the adaptation of Information Retrieval metrics to recommendation tasks, namely sparsity and popularity biases. These biases considerably distort the empirical measurements, hindering the interpretation and comparison of results across experiments. We develop a formal characterisation and analysis of the biases upon which we analyse their causes and main factors, as well as their impact on evaluation metrics under different experimental configurations, illustrating the theoretical findings with empirical evidence. We propose two experimental design approaches that effectively neutralise such biases to a large extent. We report experiments validating our proposed experimental variants, and comparing them to alternative approaches and metrics that have been defined in the literature with similar or related purposes.     

The strange case of reproducibility versus representativeness in contextual suggestion test collections

The most common approach to measuring the effectiveness of Information Retrieval systems is by using test collections. The Contextual Suggestion (CS) TREC track provides an evaluation framework for systems that recommend items to users given their geographical context. The specific nature of this track allows the participating teams to identify candidate documents either from the Open Web or from the ClueWeb12 collection, a static version of the web. In the judging pool, the documents from the Open Web and ClueWeb12 collection are distinguished. Hence, each system submission should be based only on one resource, either Open Web (identified by URLs) or ClueWeb12 (identified by ids). To achieve reproducibility, ranking web pages from ClueWeb12 should be the preferred method for scientific evaluation of CS systems, but it has been found that the systems that build their suggestion algorithms on top of input taken from the Open Web achieve consistently a higher effectiveness. Because most of the systems take a rather similar approach to making CSs, this raises the question whether systems built by researchers on top of ClueWeb12 are still representative of those that would work directly on industry-strength web search engines. Do we need to sacrifice reproducibility for the sake of representativeness? We study the difference in effectiveness between Open Web systems and ClueWeb12 systems through analyzing the relevance assessments of documents identified from both the Open Web and ClueWeb12. Then, we identify documents that overlap between the relevance assessments of the Open Web and ClueWeb12, observing a dependency between relevance assessments and the source of the document being taken from the Open Web or from ClueWeb12. After that, we identify documents from the relevance assessments of the Open Web which exist in the ClueWeb12 collection but do not exist in the ClueWeb12 relevance assessments. We use these documents to expand the ClueWeb12 relevance assessments. Our main findings are twofold. First, our empirical analysis of the relevance assessments of 2  years of CS track shows that Open Web documents receive better ratings than ClueWeb12 documents, especially if we look at the documents in the overlap. Second, our approach for selecting candidate documents from ClueWeb12 collection based on information obtained from the Open Web makes an improvement step towards partially bridging the gap in effectiveness between Open Web and ClueWeb12 systems, while at the same time we achieve reproducible results on well-known representative sample of the web.     

Influence of football match time–motion parameters on recovery time course of muscle damage and jump ability

ABSTRACT

We analysed the time course of recovery of creatine kinase (CK) and countermovement jump (CMJ) parameters after a football match, and correlations between changes in these variables and match time–motion parameters (GPS-accelerometry) in 15 U-19 elite male players. Plasma CK and CMJ height (CMJ_H), average concentric force (CMJ_CON) and average eccentric force (CMJ_ECC) were assessed 2 h before and 30 min, 24 h and 48 h post-match. There were substantially higher CK levels 30 min, 24 h and 48 h (ES: 0.43, 0.62, 0.40, respectively), post-match. CMJ_ECC (ES: ?0.38), CMJ_H (ES: ?0.35) decreased 30 min post, CMJ_CON (ES: ?0.35), CMJ_ECC (ES: ?0.35) and CMJ_H (ES: ?1.35) decreased 24 h post, and CMJ_CON (ES: ?0.41) and CMJ_H (ES: ?0.53) decreased 48 h post. We found correlations between distance covered at velocities ≤21 km · h^?1 and changes in CK at 24 h (r = 0.56) and at 48 h (r = 0.54) and correlations between CK and distance covered >14 km · h^?1 (r = 0.50), accelerations (r = 0.48), and decelerations (r = 0.58) at 48 h. Changes in CMJ_CON 30 min and 24 h post (both r = ?0.68) correlated with impacts >7.1·G. Decelerations >2 m · s^?2 correlated with changes CMJ_CON (r = ?0.49) at 48 h and CMJ_ECC (r = ?0.47) at 30 min. Our results suggest that match GPS-accelerometry parameters may predict muscle damage and changes in components of neuromuscular performance immediately and 24–48 h post-match.     

What counts as science? Expansive learning actions for teaching and learning science with bilingual children

Cultural Studies of Science Education - Science education should help children acquire sophisticated understandings about science, how it is done, and how they can be scientists. Consequently,...     

Impact of an incremental running test on jumping kinematics in endurance runners: can jumping kinematic explain the post-activation potentiation phenomenon?

This study aimed to determine whether kinematic data during countermovement jump (CMJ) might explain post-activation potentiation (PAP) phenomenon after an exhausting running test. Thirty-three trained endurance runners performed the Léger Test; an incremental test which consists of continuous running between two lines 20 m apart. CMJ performance was determined before (pre-test) and immediately after the protocol (post-test). Sagittal plane, video of CMJs was recorded and kinematic data were obtained throughout 2-Dimensional analysis. In addition to the duration of eccentric and concentric phases of CMJ, hip, knee and ankle angles were measured at four key points during CMJ: the lowest position of the squat, take-off, landing, and at the lowest position after landing. Additionally, heart rate was monitored, and rate of perceived exertion was recorded at post-test. Analysis of variance revealed a significant improvement in CMJ (p = 0.002) at post-test. Cluster analysis grouped according to whether PAP was experienced (responders group: RG, n = 25) or not (non-responders group: NRG, n = 8) relative to CMJ change from rest to post-test. RG significantly improved (p < 0.001) the performance in CMJ, whereas NRG remained unchanged. Kinematic data did not show significant differences between RG and NRG. Thus, the data suggest that jumping kinematic does not provide the necessary information to explain PAP phenomenon after intensive running exercises in endurance athletes.     

Primeras creaciones en el lenguaje infantil. El caso de las metáforas

Resumen

La mayoría de los autores reconoce que el niño crea múltiples términos y expresiones cuando empieza a hablar. Estas creaciones (muchas veces erróneas desde nuestro punto de vista), revelan el empleo de diferentes reglas lingüísticas.

Uno de los motivos que conducen al niño pequeño a crear nuevos términos es el metafórico: designar un objeto con un término que normalmente se aplica a otro objeto, similar al primero. Podríamos entonces pensar que el niño, de dos a seis años, es capaz de emplear y comprender el lenguaje figurado, y particularmente las metáforas. Esta hipótesis es criticada a la luz de una serie de hechos experimentales relativos al desarrollo cognitivo del niño.