An implicit feedback approach for interactive information retrieval

Searchers can face problems finding the information they seek. One reason for this is that they may have difficulty devising queries to express their information needs. In this article, we describe an approach that uses unobtrusive monitoring of interaction to proactively support searchers. The approach chooses terms to better represent information needs by monitoring searcher interaction with different representations of top-ranked documents. Information needs are dynamic and can change as a searcher views information. The approach we propose gathers evidence on potential changes in these needs and uses this evidence to choose new retrieval strategies. We present an evaluation of how well our technique estimates information needs, how well it estimates changes in these needs and the appropriateness of the interface support it offers. The results are presented and the avenues for future research identified.     

The integration of computer simulation and learning support: An example from the physics domain of collisions

Discovery learning is generally seen as a promising but demanding mode of learning that, in most cases, can only be successful if students are guided in the discovery process. The present article discusses a study on discovery learning with a computer simulation environment in the physics domain of collisions. In the learning environment, which is called Collision, students learned about collisions where two particles move in the same direction and interact via a conservative force in such a way that the total mechanical energy is conserved. In the experiment we conducted with Collision, we evaluated the effects of adding two different ways to guide students: model progression, in which the model is presented in separate parts; and assignments, small exercises that the student can choose to do. The effect of providing assignments and model progression was evaluated by comparing the learning behavior and learning results over three experimental conditions in which different versions of the simulation environment were presented: pure simulation, simulation plus assignments, and simulation plus model progression and assignments. Students' use of the environment was logged, their subjectively experienced workload was measured on‐line, and their learning was assessed using a number of assessment procedures. Providing assignments with the simulation improved students' performance on one aspect of a so‐called intuitive knowledge test. Providing the students with model progression did not have an effect. A subjective workload measure indicated that expanding the simulation with assignments and model progression did not raise the workload experienced by the students. © 1999 John Wiley & Sons, Inc. J Res Sci Teach 36: 597–615, 1999     

Decentralized neural identification and control for uncertain nonlinear systems: Application to planar robot

This paper presents a discrete-time decentralized neural identification and control for large-scale uncertain nonlinear systems, which is developed using recurrent high order neural networks (RHONN); the neural network learning algorithm uses an extended Kalman filter (EKF). The discrete-time control law proposed is based on block control and sliding mode techniques. The control algorithm is first simulated, and then implemented in real time for a two degree of freedom (DOF) planar robot.     

The location of the tibial accelerometer does influence impact acceleration parameters during running

Tibial accelerations have been associated with a number of running injuries. However, studies attaching the tibial accelerometer on the proximal section are as numerous as those attaching the accelerometer on the distal section. This study aimed to investigate whether accelerometer location influences acceleration parameters commonly reported in running literature. To fulfil this purpose, 30 athletes ran at 2.22, 2.78 and 3.33 m · s^–1 with three accelerometers attached with double-sided tape and tightened to the participants’ tolerance on the forehead, the proximal section of the tibia and the distal section of the tibia. Time-domain (peak acceleration, shock attenuation) and frequency-domain parameters (peak frequency, peak power, signal magnitude and shock attenuation in both the low and high frequency ranges) were calculated for each of the tibial locations. The distal accelerometer registered greater tibial acceleration peak and shock attenuation compared to the proximal accelerometer. With respect to the frequency-domain analysis, the distal accelerometer provided greater values of all the low-frequency parameters, whereas no difference was observed for the high-frequency parameters. These findings suggest that the location of the tibial accelerometer does influence the acceleration signal parameters, and thus, researchers should carefully consider the location they choose to place the accelerometer so that equivalent comparisons across studies can be made.     

Mediation role of cardiorespiratory fitness on the association between fatness and cardiometabolic risk in European adolescents: The HELENA study

PurposeThis study was aimed to analyze the mediation role of cardiorespiratory fitness (CRF) on the association between fatness and cardiometabolic risk scores (CMRs) in European adolescents.MethodsA cross-sectional study was conducted in adolescents (n = 525; 46% boys; 14.1 ± 1.1 years old, mean ± SD) from 10 European cities involved in the Healthy Lifestyle in Europe by Nutrition in Adolescence study. CRF was measured by means of the shuttle run test, while fatness measures included body mass index (BMI), waist to height ratio, and fat mass index estimated from skinfold thicknesses. A clustered CMRs was computed by summing the standardized values of homeostasis model assessment, systolic blood pressure, triglycerides, total cholesterol/high-density lipoprotein cholesterol ratio, and leptin.ResultsLinear regression models indicated that CRF acted as an important and partial mediator in the association between fatness and CMRs in 12–17-year-old adolescents (for BMI: coefficients of the indirect role β = 0.058 (95% confidence interval (95%CI): 0.023–0.101), Sobel test z = 3.11 (10.0% mediation); for waist to height ratio: β = 4.279 (95%CI: 2.242–7.059), z =3.86 (11.5% mediation); and for fat mass index: β = 0.060 (95%CI: 0.020–0.106), z = 2.85 (9.4% mediation); all p < 0.01).ConclusionIn adolescents, the association between fatness and CMRs could be partially decreased with improvements to fitness levels; therefore, CRF contribution both in the clinical field and public health could be important to consider and promote in adolescents independently of their fatness levels.     

Intermittent hypoxia exposure in a hypobaric chamber and erythropoietin abuse interpretation

The aim of this study was to assess the effect of intermittent hypoxia exposure on direct and indirect methods used to evaluate recombinant human erythropoietin (rhEPO) misuse. Sixteen male triathletes were randomly assigned to either the intermittent hypoxia exposure group (experimental group) or the control normoxic group (control group). The members of the experimental group were exposed to simulated altitude (from 4000 to 5500 m) in a hypobaric chamber for 3 h per day, 5 days a week, for 4 weeks. Blood and urine samples were collected before and after the first and the final exposures, and again 2 weeks after the final exposure. While serum EPO significantly increased after the first [from a mean 8.3 IU x l(-1) (s = 3.2) to 16.6 IU x l(-1) (s = 4.7)] and final exposures [from 4.6 IU x l(-1) (s = 1.4) to 24.8 IU x l(-1) (s = 9.3)], haemoglobin, percentage of reticulocytes, and soluble transferrin receptor were not elevated. Second-generation ON/OFF models (indirect rhEPO misuse detection) were insensitive to intermittent hypoxia exposure. The distribution of the urinary EPO isoelectric profiles (direct rhEPO misuse detection) was altered after intermittent hypoxia exposure with a slight shift towards more basic isoforms. However, those shifts never resulted in misinterpretation of results. The intermittent hypoxia exposure protocol studied did not produce any false-positive result for indirect or direct detection of rhEPO misuse in spite of the changes in EPO serum concentrations and urinary EPO isoelectric profiles, respectively.     

Changes in the school and non-school sedentary time in youth: The UP&DOWN longitudinal study

ABSTRACT

The aims of this study were (i) to examine the sedentary time (ST) during different time periods [i.e., weekend, out-of-school weekdays hours, school hours, recess, physical education classes (PEC)] in children and adolescents; (ii) to identify 2-year longitudinal changes in the ST for these periods; and (iii) to examine if ST at baseline is associated with ST 2 years later. This was a 2-year follow-up study with 826 (51.9% boys) children and 678 (50.7% boys) adolescents. Accelerometers were used to assess ST. Students spent more than 60% of their weekend, out-of-school hours and school hours in ST. During these periods, girls and adolescents were more sedentary than boys and children, respectively (p < 0.05). Over 2-year follow-up, ST increased during the weekend, out-of-school hours, school hours and recess in all subgroups studied (p < 0.001). ST during PEC declined 2% per year in children (p < 0.001) but it increased in adolescents (p < 0.05). ST during the periods analysed at baseline was lowly associated with ST during these periods 2 years later (intraclass correlations from <0.001 to 0.364). Interventions in these settings may be adequate if the intention is to avoid ST increase in students.     

Modulation of general and specific cognitive precursors to early mathematical competencies in preschool children

European Journal of Psychology of Education - The main goal of this study was to analyze the contribution of predictors of both domain-general (working memory, processing speed, and receptive...     

Nothing to do with me! Teachers’ perceptions on cultural diversity in Spanish secondary schools

One of the key effects of globalisation is the extraordinary increase in migratory movements. Spain, a country traditionally accustomed to emigration, has seen a considerable rise in the influx of immigrant population, with notable demographic, social and cultural transformations. Particularly, since the early 90s, schools have been experiencing increasing ethnic diversity in their student enrolments. Especially, over the last 10 years, their presence has multiplied 10-fold, reaching 9.53% of the total student body. Thus, along with linguistic difference, class, gender or ability, the most characteristic feature of Spanish schools in recent years is their multicultural nature. For these reasons, it seems reasonable to focus on how Spanish schools, and particularly teachers, perceive and manage cultural diversity. This article reports on a multiple case design study concerning the teachers’ views on cultural diversity and the impact on daily practice in their classrooms. Participants included 16 teachers, with experience ranging from 2 to 20 years of teaching, from four Spanish secondary schools. Semi-structured in-depth interviews with the teachers from each school were chosen as the research method. Additionally, the principal and four immigrant student families from each school were also interviewed. Further information was obtained through a focus-group interview with the four school counsellors. Over a six-month period, all the interviews and complementary field work were carried out by a researcher in each school. While recognising the efforts to accommodate ethnic groups and immigrant populations, the results indicated that teachers perceive cultural diversity as a particular problem whose management is marginalised and excluded from the set of school activities and teaching practices. Teachers agree that the issue is one of adaptation, a problem to be solved by the students themselves with the support of school counsellors and other educational specialists. This way, neither school policies nor teaching practices assume the commitments arising from cultural diversity, so we cannot say that teachers incorporate it in their work, putting culturally relevant teaching into practice in their classrooms. While one of the benchmarks achieved in recent years is the presence of educational specialists in schools to address cultural diversity, the next step is to create the conditions to articulate a joint and collaborative effort between the teaching body and these professionals, bringing cultural diversity management closer to the classroom. Another pending challenge would be determining how we can best prepare teachers for organising and managing their culturally diverse classrooms. Teachers in these schools are doing their job without a professional knowledge base concerning multicultural education. Therefore, pre-service and in-service teacher education programmes should consider questions related to multicultural education and classroom management, which are absent or rarely taken into account in teacher training to date.