Experimental validation of numerical study on thermoelectric-based heating in an integrated centrifugal microfluidic platform for polymerase chain reaction amplification     

Mary Amasia  Seok-Won Kang  Debjyoti Banerjee  Marc Madou 《Biomicrofluidics》2013,7(1)

A comprehensive study involving numerical analysis and experimental validation of temperature transients within a microchamber was performed for thermocycling operation in an integrated centrifugal microfluidic platform for polymerase chain reaction (PCR) amplification. Controlled heating and cooling of biological samples are essential processes in many sample preparation and detection steps for micro-total analysis systems. Specifically, the PCR process relies on highly controllable and uniform heating of nucleic acid samples for successful and efficient amplification. In these miniaturized systems, the heating process is often performed more rapidly, making the temperature control more difficult, and adding complexity to the integrated hardware system. To gain further insight into the complex temperature profiles within the PCR microchamber, numerical simulations using computational fluid dynamics and computational heat transfer were performed. The designed integrated centrifugal microfluidics platform utilizes thermoelectrics for ice-valving and thermocycling for PCR amplification. Embedded micro-thermocouples were used to record the static and dynamic thermal responses in the experiments. The data collected was subsequently used for computational validation of the numerical predictions for the system response during thermocycling, and these simulations were found to be in agreement with the experimental data to within ∼97%. When thermal contact resistance values were incorporated in the simulations, the numerical predictions were found to be in agreement with the experimental data to within ∼99.9%. This in-depth numerical modeling and experimental validation of a complex single-sided heating platform provide insights into hardware and system design for multi-layered polymer microfluidic systems. In addition, the biological capability along with the practical feasibility of the integrated system is demonstrated by successfully performing PCR amplification of a Group B Streptococcus gene.  相似文献   

Effects of inertia correction and resistive load on fatigue during repeated sprints on a friction-loaded cycle ergometer     

Gregory Bogdanis  Aggeliki Papaspyrou  Henryk Lakomy  Mary Nevill 《Journal of sports sciences》2013,31(13):1437-1445

Abstract

Seven 6 s sprints with 30 s recovery between sprints were performed against two resistive loads: 50 (L50) and 100 (L100) g · kg^?1 body mass. Inertia-corrected and -uncorrected peak and mean power output were calculated. Corrected peak power output in corresponding sprints and the drop in peak power output relative to sprint 1 were not different in the two conditions, despite the fact that mean power output was 15–20% higher in L100 (P < 0.01). The effect of inertia correction on power output was more pronounced for the lighter load (L50), with uncorrected peak power output in sprint 1 being 42% lower than the corresponding corrected peak power output, while this was only 16% in L100. Fatigue assessed by the drop in uncorrected peak and mean power output in sprint 7 relative to sprint 1 was less compared with that obtained by corrected power values, especially in L50 (drop in uncorrected vs. corrected peak power output: 13.3 ± 2.2% vs. 23.1 ± 4.1%, P < 0.01). However, in L100, the difference between the drop in corrected and uncorrected mean power output in sprint 7 was much smaller (24.2 ± 3.1% and 21.2 ± 2.7%, P < 0.01), indicating that fatigue may be safely assessed even without inertia correction when a heavy load is used. In conclusion, when inertia correction is performed, fatigue during repeated sprints is unaffected by resistive load. When inertia correction is omitted, both power output and the fatigue profile are underestimated by an amount dependent on resistive load. In cases where inertia correction is not possible during a repeated sprints test, a heavy load may be preferable.  相似文献   

Children's Activity Rating Scale (CARS): Description and Calibration     

Jackie Puhl  Kathryn Greaves  Mary Hoyt  Tom Baranowski 《Research quarterly for exercise and sport》2013,84(1):26-36

Abstract

A five-level Children's Activity Rating Scale (CARS) was designed to categorize the intensity of physical activities and discriminate between levels of energy expenditure in young children. The CARS was used by trained observers over a 12-month period to assess physical activities of 3-4 year-old children during field observations. Agreement among observers using the CARS was 84.1% for 389 paired observation periods. The energy expenditure for each level was assessed by measuring VO₂s and heart rates of 5-6 year-old children (12 boys, 13 girls) while they performed eight activities representing the CARS levels. Mean VO₂s for the eight activities in Levels 1-5 ranged from 7.1 to 37.5 ml kg BW^?1 min^?1 (1 to 5.42 METS; 145% to 80.6% of VO₂max). Mean heart rates ranged from 89 to 183 b min^?1 for activities in Levels 1-5. VO₂s and heart rates at each level were significantly different from all other levels. These data demonstrate that the CARS encompasses a wide range of energy expenditures, discriminates between levels of energy expenditure, and can be used by trained observers to reliably evaluate physical activity and estimate energy expenditure of young children.  相似文献   

Index for Volume 59 (1988)     

Deborah Rohm Young PhD  Mary A. Steinhardt EdD 《Research quarterly for exercise and sport》2013,84(4):377-384

Abstract

Numerous epidemiological investigations have shown that low physical fitness and low physical activity are related to the incidence of coronary artery disease (CAD). Most studies, however, have not examined both variables concurrently to determine which has the strongest association with CAD risk. The purpose of the investigation was to cross-sectionally examine the relationships among physical fitness, physical activity, and risk factors for CAD. Male law enforcement officers (N = 412) from the City of Austin, Texas, were subjects for this study. Physical fitness, physical activity, and risk factors for CAD were assessed through health screenings and from data collected as part of an annual physical fitness assessment. Multivariate analysis of covariance revealed that physical fitness, but not physical activity, was related to several single CAD risk factors. Percent body fat, smoking habits, and Type A behavior score were negatively related to physical fitness level, and high density lipoprotein (HDL) cholesterol was positively related to physical fitness level. Univariate analysis of variance found both physical fitness and physical activity to be significantly related to a composite CAD risk score. Low physical fitness and low physical activity were associated with a high CAD risk score. These data suggest that physical activity must be sufficient to influence physical fitness before statistically significant risk-reducing benefits on single CAD risk factors are obtained, although minimal engagement in weekly vigorous activity provides a significant benefit for the composite CAD risk score. It is plausible, however, that physical fitness is a stronger measure than physical activity and optimally characterizes the relationship among physical activity and CAD risk factors.  相似文献   

An Analysis of the Relationship between Somatotype and Personality Traits of College Women     

Mary Slaughter 《Research quarterly for exercise and sport》2013,84(4):569-575

Abstract

The underlying rationale for the study was based on the conviction that biological factors are important in accounting for human behavior. This study was undertaken to compare the results of selected personality traits with the somatotypes of college women. Somatotypes were determined by the use of somatotype ratings as established by Sheldon. The personality profiles were determined by two personality measuring instruments: (a) the Sixteen Personality Factor Questionnaire, and (b) the California Psychological Inventory. Of the 23 hypotheses which were arbitrarily derived from Sheldon's work on physique and temperament of men, only one proved to be tenable. This tenable hypothesis stated that the component of mesomorphy is significantly correlated with the second order Factor I of the 16 PF (Low Anxiety).  相似文献   

Effect of Guided Practice on Overhand-Throw Ball Velocities of Kindergarten Children     

Lolas E. Halverson  Mary Ann Roberton  M. Joanne Safrit  Thomas W. Roberts 《Research quarterly for exercise and sport》2013,84(2):311-318

Abstract

Forty-five children from two intact kindergartens in one school were randomly assigned by sex to (a) an experimental group which received a movement program that included 120 min of guided practice in the overhand throw; or (b) a control group which received the same movement program but no exposure to the throw. A third group (N = 24), randomly selected by sex from a comparable school, received no movement program. Before and after the eight-week instructional period, ten trials of each child's overhand throw for force were filmed. Horizontal ball velocities were simultaneously recorded. ANOVAs on pre- and posttest ball velocities for each sex within each treatment group revealed no significant practice effect over ten trials (p > .05); thus, the trial mean was used as each subject's score. Two-way ANOVAs (treatment X sex) on the pre- and posttest data indicated no significant velocity differences (p > .05) between groups either before or after instruction. Boys had significantly greater velocities than girls (p < .05). Eight weeks of instruction that included 120 min of guided practice in the overarm throw did not significantly change the ball velocities of kindergarten children when compared to two groups with no formal throwing experience.  相似文献   

Pre-longitudinal Screening of Motor Development Sequences     

Mary Ann Roberton  Kathleen Williams  Stephen Langendorfer 《Research quarterly for exercise and sport》2013,84(4):724-731

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Number of Reinforcements and Memory Trace for Kinesthetically Monitored Force Reproduction     

Dr. Mary Lou Norrie 《Research quarterly for exercise and sport》2013,84(2):338-342

Abstract

The effect of the number of reinforcements on the memory trace for a kinesthetically monitored force reproduction task was studied. Sixty college women were divided by a balanced order into three groups of 20 each. One group had one reinforcement, one had five reinforcements, and the third had nine reinforcements. The reproduction attempt was either immediate or after a 30-sec. delay. Analysis of variance for constant error indicated that multiple reinforcements improved the accuracy of performance for immediate reproduction but that the improvement was not retained over a retention interval of 30 sec. The tendency to overshoot the standard occurred for both the immediate and delayed reproduction conditions.  相似文献   

Student attitudes towards and use of ICT in course study,work and social activity: A technology acceptance model approach     

Rob Edmunds  Mary Thorpe  Grainne Conole 《British journal of educational technology : journal of the Council for Educational Technology》2012,43(1):71-84

The increasing use of information and communication technology (ICT) in higher education has been explored largely in relation to student experience of coursework and university life. Students' lives and experience beyond the university have been largely unexplored. Research into student experience of ICT used a validated model—the technology acceptance model—to explore the influence of work and social/leisure contexts as well as course study, on attitudes towards and take up of technology. The results suggest that usefulness and ease of use are key dimensions of students' attitudes towards technology in all three contexts but that ICT is perceived most positively in the context of work and technology use at work is an important driver for technology use in other areas.  相似文献   

How inconvenient assumptions affect preservice teachers’ uptake of new interactional patterns in mathematics: analysis and aspiration through a bifocal lens     

Mary Klein 《Educational Studies in Mathematics》2012,80(1-2):25-40

In this paper, I highlight the inadequacies of contemporary theoretical and philosophical orthodoxies to fully address pedagogic change. The required change is in mathematics education, and it has to do with enabling preservice teachers, upon graduation, to rework extant power relations in implementing new interactional patterns that centre the mathematics and the learner in dynamic, productive interaction. I interpret data from published research and my own teaching using psychological, overlaid with poststructuralist, constructs of the relationship between knowledge and action. In data interpretation I read through the words for a psychological interpretation (meaning), and I look at the words for poststructuralist indications of subjectification and identity formation (related to how well students recognise themselves as full participants in the combined discourses of mathematics and education). I have my cake and eat it; contradictory notions of the learner and learning to teach in innovative ways are held together to demonstrate (a) how it can happen that a teacher educator’s aspirations can be held ransom to constituted assumptions that inconveniently work against change, and (b) how the recognition that humanist assumptions, mathematical proficiency and agency are discursively constituted (Davies, 1990) can suggest avenues for change in teacher education.  相似文献