What mathematical competencies does a citizen need to interpret Mexico’s official information about the COVID-19 pandemic?

Educational Studies in Mathematics - We report a study on mathematical literacy with special emphasis on health literacy. In particular, we identify and characterize the mathematical competencies...     

The Impact of Design-Based STEM Integration Curricula on Student Achievement in Engineering,Science, and Mathematics

The new science education reform documents call for integration of engineering into K-12 science classes. Engineering design and practices are new to most science teachers, meaning that implementing effective engineering instruction is likely to be challenging. This quasi-experimental study explored the influence of teacher-developed, engineering design-based science curriculum units on learning and achievement among grade 4–8 students of different races, gender, special education status, and limited English proficiency (LEP) status. Treatment and control students (n = 4450) completed pretest and posttest assessments in science, engineering, and mathematics as well as a state-mandated mathematics test. Single-level regression results for science outcomes favored the treatment for one science assessment (physical science, heat transfer), but multilevel analyses showed no significant treatment effect. We also found that engineering integration had different effects across race and gender and that teacher gender can reduce or exacerbate the gap in engineering achievement for student subgroups depending on the outcome. Other teacher factors such as the quality of engineering-focused science units and engineering instruction were predictive of student achievement in engineering. Implications for practice are discussed.     

Heat Transfer in Packed Bed Heat Recuperators—I. A Precision Numerical Analysis

An extensive literature survey is reported that verifies the need for a more precise representation of the heat transfer film coefficient in packed beds. A precision numerical analysis scheme is developed for a much more general model than previously reported. Application of the results to the experimental data will be reported in Part II of the paper.     

Potential adverse cardiac remodelling in highly trained athletes: still unknown clinical significance

Moderate endurance exercise has long been considered an essential element to maintain cardiovascular health, and sedentary behaviour in the general population has been related to a significant increase in all-causes of mortality, cardiovascular disease mortality and cardiovascular disease incidence. However, a growing group of people performs an intense exercise that leads to multiple heart adaptive changes that are collectively called “athlete’s heart”. In this review, we discussed the evidence of cardiac remodelling process secondary to repetitive and strenuous exercise in some predisposed athletes that produces intense and probably deleterious changes in cardiac morphology and function with no clear clinical significance in long-term follow-up. Moreover, we also discussed the individual biological response to exercise assessed by myocardial damage, inflammation, oxidative stress, fibrosis and ventricular hypertrophy biomarkers showing different intensities with equivalent exertion.     

Why robots should not be treated like animals

Responsible Robotics is about developing robots in ways that take their social implications into account, which includes conceptually framing robots and their role in the world accurately. We are now in the process of incorporating robots into our world and we are trying to figure out what to make of them and where to put them in our conceptual, physical, economic, legal, emotional and moral world. How humans think about robots, especially humanoid social robots, which elicit complex and sometimes disconcerting reactions, is not predetermined. The animal–robot analogy is one of the most commonly used in attempting to frame interactions between humans and robots and it also tends to push in the direction of blurring the distinction between humans and machines. We argue that, despite some shared characteristics, when it comes to thinking about the moral status of humanoid robots, legal liability, and the impact of treatment of humanoid robots on how humans treat one another, analogies with animals are misleading.     

Suppression of DC-link voltage unbalance in three-level neutral-point clamped converters

Two different control approaches for suppressing DC-link voltage unbalance in Three-Level Neutral-Point Clamped Converters (NPCs) are presented in this paper. They both guarantee DC-link voltage equalization over any NPC operating conditions, i.e. when the NPC feeds or is supplied by the main AC grid at different active and/or reactive power rates. The proposed control approaches consist of either a hysteresis or a proportional regulator, each of which synthesizes the most suitable control action based on the actual DC-link voltage unbalance. Particularly, two different PWM techniques have been developed in order to achieve DC-link voltage equalization successfully, preserving NPC voltage and current waveforms at the same time. The performances achievable by means of both the proposed control approaches have been compared to each other through an extensive simulation study in order to highlight their most important advantages and drawbacks, as well as their effectiveness over any operating conditions. Particularly, both control approaches are validated in the Matlab-Simulink environment referring to DC-link voltage equalization of an NPC that represents the point of common coupling between a DC microgrid and the main AC grid.     

Geographic dispersion and co-location in global R&D portfolios: Consequences for firm performance

We examine how the ways in which firms geographically configure their global portfolios of R&D units influence the effectiveness of firms’ own R&D investments and of external technical knowledge in enhancing firm performance. Our analysis indicates that the strength of these effects depends on the extent to which firms spread their R&D units across countries (geographic dispersion of R&D) and the extent to which firms establish multiple R&D units within each country (co-location of R&D). We show that geographic dispersion and co-location are associated with distinct value creation and value capture mechanisms and in turn lead to different performance outcomes. Although geographic dispersion enhances the effects of a firm’s own R&D on its performance, R&D co-location limits such effects. These relationships are reversed when we consider the effects of external technical knowledge on firm performance. R&D co-location, rather than geographic dispersion, is what renders the exploitation of external knowledge more effective in enhancing firm performance. Our results suggest that future research should shift its focus from the degree of R&D globalization to how a portfolio is globalized and geographically structured.     

Validity and reliability of a novel iPhone app for the measurement of barbell velocity and 1RM on the bench-press exercise

The purpose of this study was to analyse the validity and reliability of a novel iPhone app (named: PowerLift) for the measurement of mean velocity on the bench-press exercise. Additionally, the accuracy of the estimation of the 1-Repetition maximum (1RM) using the load–velocity relationship was tested. To do this, 10 powerlifters (Mean (SD): age = 26.5 ± 6.5 years; bench press 1RM · kg^?1 = 1.34 ± 0.25) completed an incremental test on the bench-press exercise with 5 different loads (75–100% 1RM), while the mean velocity of the barbell was registered using a linear transducer (LT) and Powerlift. Results showed a very high correlation between the LT and the app (r = 0.94, SEE = 0.028 m · s^?1) for the measurement of mean velocity. Bland–Altman plots (R² = 0.011) and intraclass correlation coefficient (ICC = 0.965) revealed a very high agreement between both devices. A systematic bias by which the app registered slightly higher values than the LT (P < 0.05; mean difference (SD) between instruments = 0.008 ± 0.03 m · s^?1). Finally, actual and estimated 1RM using the app were highly correlated (r = 0.98, mean difference (SD) = 5.5 ± 9.6 kg, P < 0.05). The app was found to be highly valid and reliable in comparison with a LT. These findings could have valuable practical applications for strength and conditioning coaches who wish to measure barbell velocity in the bench-press exercise.     

Effects of different exercise intensities in the morning on football performance components in the afternoon

The aim of this study was to investigate the effect of two different exercise interventions in the morning on football-specific components of performance in the afternoon under conditions simulating a competition day. In the morning on 3 experimental days, 12 football players (age 24.1?±?5.5 years) completed three different preload interventions that were applied in a counter-balanced order: (1) no intervention (NI); (2) moderate-intensive exercise (MI); and (3) high-intensive exercise (HI). The subjects performed the preload exercises, consisting of a small-sided game and repeated maximal sprints, from 10:00–11:00 a.m. At 3:00 p.m., the Bangsbo test (BT) was applied to examine the effects of the different morning interventions on football-specific endurance capacity. The results showed that the HI led to significantly higher blood-lactate concentrations (moderate to very large effect) and heart rates (very large to extremely large effect) compared to the MI. In addition, there was a significant measurement?×?intervention effect on concentrations of adrenalin and noradrenalin in the urine, which reached higher values immediately after the HI (very large effect) and MI (moderate effect) compared to NI. All effects disappeared by the time of the BT in the afternoon. During all trials, after the preload intervention, reaction time and critical flicker fusion frequency increased significantly compared to the baseline morning values (reaction time: small; critical flicker fusion: trivial to small effect), but no measurement?×?intervention interaction was found. During the BT, the mean total distance covered (trivial to small effect) and the pacing pattern did not differ significantly among the trials despite numerous small individual effects. We conclude that exercise interventions of various intensities in the morning have no general effect on football-specific components of performance in the afternoon despite significant metabolic, endocrinological and cognitive short-term effects. Coaches should consider individual preferences when prescribing competition-day procedures.