Characterization of Suspension Polymerized Polyacrylamide and Poly(sodium acrylate-acrylamide) Copolymer and their Size Influence on the Properties of Concrete

Shrinkage leading to cracking and mechanical instability is a major problem for concrete due to the loss of water during the curing process. However, through the addition of Superabsorbent Polymer (SAP) hydrogels, shrinkage can be prevented, increasing the strength of concrete. Characterization of suspension polymerized polyacrylamide (PAM) poly(sodium acrylate-polyacrylamide) (PANa-PAM) copolymer microsphere sizes, morphology and swelling behavior was conducted before adding them to concrete. Size was determined using microscopy paired with ImageJ analysis. Coulter Counter size characterization was also used to determine the particle size distribution. Swelling behavior was determined using the tea bag method as well as size analysis before and after hydration. After characterization, concrete containing various sizes of SAP microspheres will be tested for shrinkage and mechanical strength. These tests will allow us to discover the optimal size of SAP microspheres in concrete to increase its mechanical properties as well as control shrinkage. We will also investigate if the shape of particles has an impact on the final properties of the concrete. The results of this study will contribute to the growing knowledge of applying SAPs in concrete and will give a better understanding on how the size and shape of SAP hydrogels influence the properties of concrete. Using this knowledge, concrete can be made to perform better resulting in more mechanically sound structures

Wind Effects on Near- and Midfield Mixing in Tidally Pulsed River Plumes

River plumes transport and mix land-based tracers into the ocean. In tidally pulsed river plumes, wind effects have long been considered negligible in modulating interfacial mixing in the energetic nearfield region. This research tests the influence of variable, realistic winds on mixing in the interior plume. A numerical model of the Merrimack River plume-shelf system is utilized, with an application of the salinity variance approach employed to identify spatial and temporal variation in advection, straining, and dissipation (mixing) of vertical salinity variance (stratification). Results indicate that moderate wind stresses (∼0.5 Pa) with a northward component countering the downcoast rotation of the plume are most effective at decreasing stratification in the domain relative to other wind conditions. Northward winds advect plume and ambient shelf stratification offshore, allowing shelf water salinity to increase in the nearshore, which strengthens the density gradient at the plume base. Straining in the plume increases with winds enhancing offshore-directed surface velocities, leading to increased shear at the plume base. Increased straining and larger density gradients at the plume base enhance variance dissipation in the near- and midfield plume, and dissipation remains enhanced if the shelf is clear of residual stratification. The smaller spatial and temporal scales of the Merrimack plume allow the mechanisms to occur at tidal time scales in direct response to instantaneous winds. This is the first study to show tidal time scale wind-induced straining and advection as controlling factors on near- and midfield mixing rates in river plumes under realistic winds

Freshwater Composition and Connectivity of the Connecticut River Plume During Ambient Flood Tides

The Connecticut River plume interacts with the strong tidal currents of the ambient receiving waters in eastern Long Island Sound. The plume formed during ambient flood tides is studied as an example of tidal river plumes entering into energetic ambient tidal environments in estuaries or continental shelves. Conservative passive freshwater tracers within a high-resolution nested hydrodynamic model are applied to determine how source waters from different parts of the tidal cycle contribute to plume composition and interact with bounding plume fronts. The connection to source waters can be cut off only under low-discharge conditions, when tides reverse surface flow through the mouth after max ambient flood. Upstream plume extent is limited because ambient tidal currents arrest the opposing plume propagation, as the tidal internal Froude number exceeds one. The downstream extent of the tidal plume always is within 20 km from the mouth, which is less than twice the ambient tidal excursion. Freshwaters in the river during the preceding ambient ebb are the oldest found in the new flood plume. Connectivity with source waters and plume fronts exhibits a strong upstream-to- downstream asymmetry. The arrested upstream front has high connectivity, as all freshwaters exiting the mouth immediately interact with this boundary. The downstream plume front has the lowest overall connectivity, as interaction is limited to the oldest waters since younger interior waters do not overtake this front. The offshore front and inshore boundary exhibit a downstream progression from younger to older waters and decreasing overall connectivity with source waters. Plume-averaged freshwater tracer concentrations and variances both exhibit an initial growth period followed by a longer decay period for the remainder of the tidal period. The plume-averaged tracer variance is increased by mouth inputs, decreased by entrainment, and destroyed by internal mixing. Peak entrainment velocities for younger waters are higher than values for older waters, indicating stronger entrainment closer to the mouth. Entrainment and mixing time scales (1–4 h at max ambient flood) are both shorter than half a tidal period, indicating entrainment and mixing are vigorous enough to rapidly diminish tracer variance within the plume

Nutritional intakes of highly trained adolescent swimmers before, during, and after a national lockdown in the COVID-19 pandemic

Strict lockdown measures were introduced in response to the COVID-19 pandemic, which caused mass disruption to adolescent swimmers’ daily routines. To measure how lockdown impacted nutritional practices in this cohort, three-day photograph food diaries were analysed at three time points: before (January), during (April), and after (September) the first UK lockdown. Thirteen swimmers (aged 15 ± 1 years) from a high-performance swimming club submitted satisfactory food diaries at all time points. During lockdown, lower amounts of energy (45.3 ± 9.8 vs. 31.1 ± 7.7 kcal∙kg BM∙day-1, p0.05), despite fewer training hours being completed (15.0 ± 1.4 vs. 19.1 ± 2.2 h∙week-1, p<0.001). These findings highlight the ability of adolescent swimmers to alter their nutrition based on their changing training circumstances when receiving sport nutrition support. However, some individuals displayed signs of suboptimal nutrition during lockdown that were not corrected once training resumed. This warrants future research to develop interactive education workshops that maintain focus and motivation towards optimal nutrition practices in isolated periods away from training

A Multidisciplinary Investigation into the Talent Development Processes in an English Premiership Rugby Union Academy: A Preliminary Study through an Ecological Lens

(1) Background: The progression of youth rugby union (RU) players towards senior professional levels can be the result of various different constraints. The aim of this study was to examine characteristics that differentiated playing positions and player rankings in an English Premiership RU academy. (2) Methods: Thirty players (mean age = 18.5 ± 2.8 years) were divided by playing positions (forwards = 18, backs = 12) and ranked (one to thirty) by coaches based on their potential to achieve senior professional status. Players were analysed across 32 characteristics from eight overreaching factors based on task, environmental, and performer constraints. MANOVA and ANOVA were used to calculate differences among variables in players’ positions (i.e., forwards vs. backs) and ranks (i.e., top 10 vs. bottom 10), with a Welch’s t-test applied to identify individual differences amongst groups and effect sizes calculated. (3) Results: Large effect sizes were found between groups for socioeconomic, sport activity, anthropometric, physical, and psychological factors. Moreover, environmental and performer constraints differentiated playing positions, whereas task and environmental constraints discriminated player ranks. (4) Conclusion: Present findings showed that playing positions and player ranks can be distinguished according to specific constraints

Nutritional Supplement Use in a UK High-Performance Swimming Club

The aim of this study was to observe the nutritional supplement practices of highly trained swimmers on a national talent pathway, since it is often reported that swimmers engage in widespread supplement use at the elite level. Thus, this study employed a validated supplement intake questionnaire with forty-four swimmers from a high-performance swimming club, which had three distinct talent stages: development (aged 11–14 years, n = 20), age-group (aged 13–17 years, n = 13), and national level (aged ≥ 16 years, n = 11). Ninety-eight percent of the interviewed swimmers reported using at least one supplement, with performance (34%) and recovery (19%) cited as the primary reasons. National swimmers used more total supplements (8.1 ± 3.4 supplements) compared to age-group (4.8 ± 2.0 supplements, p = 0.003, g = 1.17) and development (3.9 ± 1.7 supplements, p < 0.001, g = 1.69) swimmers, mostly because of a greater intake of ergogenic aids (2.4 ± 1.4 supplements vs. age-group: 0.5 ± 0.5 supplements, p < 0.001, g = 1.12; vs. development: 0.1 ± 0.2 supplements, p < 0.001, g = 1.81). Parents/guardians were the primary supplement informants of development swimmers (74%, p < 0.001, V = 0.50), whereas performance nutritionists informed ~50% of supplements used by age-group and national swimmers (p < 0.001, V = 0.51). Based on these results, supplement education and greater focus on basic sport nutrition practices may be required for parents/guardians at the development level. Moreover, further research is needed to support the high number of ergogenic aids used by national swimmers, with the efficacy of these supplements currently equivocal in the applied setting

A Comparison of Physical Activity and Sedentary Lifestyle of University Employees through ActiGraph and IPAQ-LF

Introduction: The benefits of participating in physical activity (PA) are wide-ranging, such as lowering the risk of diabetes and anxiety. Employees’ engagement in PA can also benefit their employers due to the potential reduction in absenteeism and increased productivity. However, the PA levels and sedentary behaviour of university employees are yet to be examined using a mixed methods approach. This study aimed to monitor the PA and sedentary lifestyle (SL) of university employees’ objectively and subjectively for a whole week. Methods: Sixty-four employees (male = 33; female = 31) wore a PA monitor for a whole week and simultaneously completed the International Physical Activity Questionnaire Long Form (IPAQ-LF) to evaluate light, moderate to vigorous physical activity (MVPA), and SL amongst employees from different job roles such as Academics, Administration, and Professionals Service. Results: The ActiGraph results determined that employees engaged in significantly more light PA, and MVPA compared to the self-reported IPAQ-LF (p 0.05). However, there were significant differences across gender light PA Z = –6.139, p = .001, MVPA Z = –4.962, p = .001 but no significant differences in SL Z = –.869, p = .385. Also, there were significant differences across job roles light PA, MVPA (p 0.05). Discussion and conclusion: Findings suggest, IPAQ-LF presented lower light PA, MVPA, and SL than ActiGraph. Thus, considering the impact of prolonged SL on health and wellbeing, future research is needed to explore the challenges this population faces regarding PA engagement and propose potential interventions to reduce SL amongst university employees

Citrulline Malate Fails to Improve Repeated 300 m Swimming Times in Highly Trained Swimmers

Citrulline malate (CM) has been touted as a nutritional ergogenic aid for sports performance, with purported mechanisms of increased muscle blood flow, ammonia clearance, and adenosine triphosphate resynthesis. Combined, these physiological benefits may be best applied to whole-body endurance exercises, such as swimming, though this postulate has not yet been explored. In a double-blind, randomised, and crossover design, 11 national-level swimmers (age: 17 ± 3 years, height: 1.71 ± 0.05 m, body mass: 60.6 ± 8.3 kg) from a high-performance swimming club ingested either 15 g CM or a placebo (PLA) 60 min before six × 300 m freestyle bouts (at 4.5 min intervals). Blood lactate, blood pressure, and ratings of perceived exertion were measured at baseline, 60 min post-ingestion, and immediately post-exercise. Neither mean 300 m swimming time (CM: 212.0 ± 9.6 vs. PLA: 212.8 ± 7.7 s, p = 0.683, g = 0.09) nor any individual swimming bouts (p = 0.679, Pŋ2 = 0.02) were improved with CM ingestion. Moreover, no differences in any physiological or subjective measures were identified between conditions (all p > 0.05). Whether the proposed CM mechanisms were active was unclear as more direct physiological measures (i.e., plasma NO, ammonia) may have been required. Resultantly, these observations do not support an ergogenic effect of acute CM ingestion in highly trained swimmers

Learning physics in context: a study of student learning about electricity and magnetism

This paper re-centres the discussion of student learning in physics to focus on context. In order to do so, a theoretically-motivated understanding of context is developed. Given a well-defined notion of context, data from a novel university class in electricity and magnetism are analyzed to demonstrate the central and inextricable role of context in student learning. This work sits within a broader effort to create and analyze environments which support student learning in the sciencesComment: 36 pages, 4 Figure