Optimization of handheld gauge sizes for rocker measurements of skate blades and bobsleigh runners

This work uses numerical methods to investigate the feasibility of modifying an instrument used in speed skating to analyze blades from four different ice sports. The instrument, a handheld rocker gauge, is adapted to create a device that can effectively profile other types of skate blades and bobsleigh runners. Since there are significant differences between short and long-track blades one could expect a difference in the gauges used to study these blades. Despite this expectation, the same gauge is used in both disciplines. The usefulness of these gauges has been proven in speed skating so it is expected that they should also be useful to study hockey blades and bobsleigh runners. To optimize the gauge size for different blade types we digitize the profile of a blade, which we use to simulate gauge data. Then we use that gauge data to reconstruct the profile and compare it to the original digital profile. The result is compared for various gauge sizes and the gauge size is optimized for each of the four disciplines. The only commercially available device seems optimal for bobsleigh and long track speed skating. Smaller gauges are recommended for analyzing short track speed skates and hockey skates.

The relationships between self-assessed habitual physical activity and non-invasive measures of cardiac autonomic modulation in young healthy volunteers

Heart rate variability estimates cardiac autonomic modulation, but the relationship between habitual physical activity and heart rate variability remains unclear. The aims of this study were to compare RR-interval and heart rate variability indices in individuals of different habitual physical activity levels, and examine the relationship between habitual physical activity and heart rate variability. Ninety-two healthy volunteers (47 men, 45 women; mean age 23.1 years, s = 2.1) were divided into tertiles according to the Baecke Questionnaire score. Standard heart rate variability indices were derived from 5-min resting RR-interval recordings with paced respiration (0.25 Hz). Between-group differences and the relationship between habitual physical activity and heart rate variability were assessed. More active participants (tertiles 2-3) had longer RR-intervals than those in tertile 1 (P < 0.05). Participants in tertile 2 had higher root mean squared differences of successive normal RR-intervals than those in tertile 1 and a higher standard deviation of normal RR-intervals than those in tertiles 1 and 3. There was a positive linear relationship between habitual activity and RR-interval. Differing RR-interval lengths were found in subgroups of young individuals according to level of habitual physical activity. More active individuals showed resting bradycardia without evidence of enhanced cardiac parasympathetic modulation. The mechanism linking habitual physical activity and RR-interval length appears to be independent of physiological mechanisms that can be measured by heart rate variability.     

Influence of the composition of artificial turf on rotational traction and athlete biomechanics

Artificial turf advances have enabled surfaces to behave like natural grass, however, debate remains as to whether artificial turf is as safe as natural grass. To reduce injury risk, sport surfaces should have low rotational traction with artificial surfaces having a potential advantage as components can be manipulated to change surface properties and traction. The purpose of this study was to investigate the influence that different components of artificial turf have on rotational traction and athlete lower extremity joint loading. Twelve surfaces underwent mechanical testing to determine the influence of fibre density, fibre length, infill composition and compaction on rotational traction. Following mechanical testing, Control, Low and High Traction surfaces were selected for biomechanical analysis, where sixteen athletes performed maximum effort v-cuts while kinematic/kinetic data were recorded on each surface. Mechanically, fibre density, type of infill and compaction of the surface each independently influenced traction. The traction differences were substantial enough to alter the athlete kinematics and kinetics. Low traction surfaces reduced ankle and knee loading, while high traction surfaces increased ankle and knee loading . Reducing the rotational traction of sport surfaces is possible through alterations of individual components, which may reduce the joint loading at the knee and ankle joint.     

The performance of global film franchises: installment effects and extension decisions

An empirical exploration of global film franchises provides insights for managers of film franchises, investors in franchisable products, and scholars interested in motion picture performance. Performance tends to deteriorate as extensions are introduced: production budgets rise, advertising expenditures remain similar, and the number of opening-weekend theaters experiences a jump with the first sequel and then remains similar in subsequent installments. However, revenue, return-on-investment (ROI) and audience and critical reviews fall, and foreign performance becomes increasingly important. Offsetting deteriorating performance, risk falls: revenue and ROI become more predictable. An early change in the lead actor causes reduced performance, but changes in key product characteristics and inputs in later installments help prolong the franchise. ROI of the current installment is the most critical financial determinant of whether a further extension will occur, but high-budget films and those with higher domestic share of revenue are also more likely to yield further extensions.     

The relationship between extension of the metatarsophalangeal joint and sprint time for 100 m Olympic athletes

Selected kinematic variables of the foot segments and the metatarsophalangeal (MTP) joint were investigated in relation to sprinting performance among 100 m sprint athletes at the 2000 Summer Olympic Games. It was hypothesized that the kinematics of the MTP joint, and forefoot and rearfoot segments, are related to sprint performance for both male and female athletes. Kinematic sagittal plane data were collected using two digital video cameras recording at 120 fields per second. It was determined that faster male sprinters experienced higher maximal rates of MTP extension, and faster female sprinters touch down with higher posterior sole angles and take off with lower posterior sole angles.     

Scan and Learn: Quick Response Code Enabled Museum for Mobile Learning of Anatomy and Pathology

In the past, medical museums played a significant role in anatomy and pathology training. The attraction of medical museums has declined recently due to the emergence of information technology and innovative medical curricula. An innovative mobile learning platform has been developed using quick response (QR) codes for the museum specimens at the Lee Kong Chain School of Medicine, Singapore. High-quality images of the potted specimens were captured and combined into an album and a video using Adobe Acrobat Pro 9 and Windows Movie Maker, respectively. Subsequently, QR codes were generated linking to PDF documents with annotations, pathology, and clinical history concerning the specimens. Quick response codes were piloted in gastrointestinal teaching module for Year 2 medical students. Survey responses were obtained from students to verify the efficacy of QR as a learning tool. The majority of students either agreed or strongly agreed that it was easy to access the information about the specimen with QR codes (4.47 ± 0.84), while 96% of students agreed that they are able to correlate the specimen with the annotated images (4.56 ± 0.56). The majority of students (78%) agreed that QR codes are useful for their learning (4.22 ± 0.87), while 75% of students felt QR codes motivate them to visit Anatomy Resource Centre. Most of the students agreed that QR codes are useful for revision of materials (4.13 ± 1.07) and independent learning (4.38 ± 0.87). These findings suggest that QR codes are not only effective for students learning but also enhance their exploration experience with the museum specimens.     

ApoStream?, a new dielectrophoretic device for antibody independent isolation and recovery of viable cancer cells from blood

Isolation and enumeration of circulating tumor cells (CTCs) are used to monitor metastatic disease progression and guide cancer therapy. However, currently available technologies are limited to cells expressing specific cell surface markers, such as epithelial cell adhesion molecule (EpCAM) or have limited specificity because they are based on cell size alone. We developed a device, ApoStream^™ that overcomes these limitations by exploiting differences in the biophysical characteristics between cancer cells and normal, healthy blood cells to capture CTCs using dielectrophoretic technology in a microfluidic flow chamber. Further, the system overcomes throughput limitations by operating in continuous mode for efficient isolation and enrichment of CTCs from blood. The performance of the device was optimized using a design of experiment approach for key operating parameters such as frequency, voltage and flow rates, and buffer formulations. Cell spiking studies were conducted using SKOV3 or MDA-MB-231 cell lines that have a high and low expression level of EpCAM, respectively, to demonstrate linearity and precision of recovery independent of EpCAM receptor levels. The average recovery of SKOV3 and MDA-MB-231 cancer cells spiked into approximately 12 × 10⁶ peripheral blood mononuclear cells obtained from 7.5 ml normal human donor blood was 75.4% ± 3.1% (n = 12) and 71.2% ± 1.6% (n = 6), respectively. The intra-day and inter-day precision coefficients of variation of the device were both less than 3%. Linear regression analysis yielded a correlation coefficient (R²) of more than 0.99 for a spiking range of 4–2600 cells. The viability of MDA-MB-231 cancer cells captured with ApoStream was greater than 97.1% and there was no difference in cell growth up to 7 days in culture compared to controls. The ApoStream device demonstrated high precision and linearity of recovery of viable cancer cells independent of their EpCAM expression level. Isolation and enrichment of viable cancer cells from ApoStream enables molecular characterization of CTCs from a wide range of cancer types.     

Footwear traction at different areas on artificial and natural grass fields

Footwear traction has been linked to lower-extremity injuries with the theory that higher traction leads to an increased incidence of injury. Recent studies have challenged this showing similar injury rates on artificial turf, which has higher traction than natural grass. This could suggest that the magnitude of traction may not be as relevant for injury as relative changes from one location to another, due to inconsistencies in the surface. The purpose of this study was to compare the traction at various locations on an in-fill artificial turf and natural grass surface. A portable traction tester measured the traction of three shoes at six locations on both surfaces. The results indicate that over the course of a season the traction on natural grass changes considerably, especially rotational traction. Surprisingly the artificial turf surface also had areas of high and low traction due to the movement of the in-fill material during play.     

Students’ Perceptions of Teacher Clarity: The Role of Cognitive Traits Across Contexts

This study explored how teacher clarity may be construed differently by students with differing traits depending upon the content of the instruction. Specifically, it examined relationships between students’ need for cognition and cognitive style and their perceptions of teacher clarity in science, technology, engineering, and math (STEM) and non-STEM classes. Results showed that participants’ need for cognition and analytic cognitive style positively predicted perceptions of teacher clarity in STEM classes but did not do so in non-STEM classes.     

A Class-Wide Intervention for Improving Homework Performance

Homework completion has an important impact on the overall academic functioning of students. Consultation requests often center on identifying efficient interventions so that teachers may facilitate the homework process and enhance students' academic achievement. This investigation employed a randomized interdependent group contingency and randomized reinforcers to improve homework completion and accuracy of spelling performance in 21 elementary school students. An ABAB reversal design across all students was employed. Results showed this intervention to have a positive impact on both spelling homework completion and accuracy rates. Limitations, future research, and contributions are addressed.