The reproducibility of perceptually regulated exercise responses during short-term cycle ergometry

This is the author's PDF version of an article published in International journal of sports medicine in 2004. The definitive version is available at www.thieme-connect.com.The purpose of this study was to assess the reproducibility over four trials of perceptually regulated exercise intensity during short-term cycle ergometry. Recent research has suggested that an improvement in the reproducibility (better agreement) of the exercise output would be observed with a repeated practice of using regulatory tools such as Borg’s 6-20 rating of perceived exertion (RPE) scale. Eighteen healthy active volunteers (nine males mean age (± SD) 24.7 ± 3.4 yr, and nine females 27.6 ± 5.4 yr) completed four identical intermittent effort production trials on a cycle ergometer, over a period of two-three weeks, with all trials being between three and five days apart. After warm-up, the volunteers were asked to produce four x three-minute bouts of exercise at RPE levels: 13, 15, 9, and 17 (in this order). Power output (W), percentage maximum heart rate reserve (%MHRR), and oxygen consumption (VO2; ml•kg-1•min-1) were recorded in the final minute of each bout. Analysis revealed that the 95% limits of agreement (LoA) between repeated trials did not decrease for the objective markers of exercise intensity, remaining wide throughout. In the worst case comparisons the LoA represented changes (expressed as a proportion of the mean of two trials) of up to 58.3% in power output (T2 vs. T3 at RPE 9), 65.5% in %MHRR (T1 vs. T2 at RPE 13) and 36.5% in VO2 (T3 vs. T4 at RPE 17). These findings question the use of ratings of perceived exertion to regulate exercise effort. That the reproducibility of effort is also not seen to improve with practice raises doubts over the validity of using the RPE scale for providing training intensities for this type of exercise.This article was submitted to the RAE2008 for the University of Chester - Allied Health Professions and Studies

Chemiluminescent Tags for Tracking Insect Movement in Darkness: Application to Moth Photo-Orientation

The flight tracks of Manduca sexta (Lepidoptera: Sphingidae) flying toward a 5 watt incandescent light bulb were recorded under low light conditions with the aid of a camera-mounted photomultiplier and a glowing marker technique. Small felt pads bearing a chemiluminescent (glowi ma­erial, Cyalume®, were affixed to the abdomens of free-flying moths. insects orienting to a dim incandescent bulb were easily visible to the naked eye and were clearly captured on videotape. On their initial approach to the light source, M. sexta were found to orient at a mean angle of -0.220 ± 2.70 (mean ± SEM). The speed of the initial approach flight (OA ± 0.03 m/s) was significantly faster than the speed immediately after passing the light (0.29 ± 0.02 m/s; t =6.4, PM. sexta initially fly approximately at a light source and only after passing it, do they engage in circular flight around the source. M. sexta flight to lights does not entirely match any paths predicted by several light orientation mechanisms, including the commonly invoked light compass theory

SYSTEMATIC AND UNSYSTEMATIC RISK OF RATES OF RETURN ASSOCIATED WITH SELECTED FOREST PRODUCTS COMPANIES

Resource /Energy Economics and Policy, Risk and Uncertainty,

Investigation of possible causes for human-performance degradation during microgravity flight

The results of the first year of a three year study of the effects of microgravity on human performance are given. Test results show support for the hypothesis that the effects of microgravity can be studied indirectly on Earth by measuring performance in an altered gravitational field. The hypothesis was that an altered gravitational field could disrupt performance on previously automated behaviors if gravity was a critical part of the stimulus complex controlling those behaviors. In addition, it was proposed that performance on secondary cognitive tasks would also degrade, especially if the subject was provided feedback about degradation on the previously automated task. In the initial experimental test of these hypotheses, there was little statistical support. However, when subjects were categorized as high or low in automated behavior, results for the former group supported the hypotheses. The predicted interaction between body orientation and level of workload in their joint effect on performance in the secondary cognitive task was significant for the group high in automatized behavior and receiving feedback, but no such interventions were found for the group high in automatized behavior but not receiving feedback, or the group low in automatized behavior

On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

In free piston Stirling engine research the integrity of both amplitude and phase of the dynamic pressure measurements is critical to the characterization of cycle dynamics and thermodynamics. It is therefore necessary to appreciate all possible sources of signal distortion when designing pressure measurement systems for this type of research. The signal distortion inherent to pressure transmission lines is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving helium-charged free piston Stirling engines. The scope and limitations of the dynamic response analysis are considered

The Evolution of Securitization in Multifamily Mortgage markets and Its Effect on lending Rates

Loan purchase and securitization by Freddie Mac, Fannie Mae and private-label commercial mortgage-backed securities (CMBS) grew rapidly during the 1990s and accounted for more than one-half of the net growth in multifamily debt over the decade. By facilitating the integration of the multifamily mortgage market into the broader capital markets, securitization helped to create new sources of credit as some traditional portfolio investors—savings institutions and life insurers—reduced their share of loan holdings. A model of commercial mortgage rates at life insurers, expressed relative to a comparable-term Treasury yield, was estimated over a twenty-two-year period. The parameter estimates supported an option-based pricing model of rate determination; proxies for CMBS activity showed no significant effect.

Preparation and Properties of In-Situ Devices Using the SALD and SALDVI Techniques

One of the many advantages of Selective Area Laser Deposition (SALD) and Selective Area Laser Deposition Vapor Infiltration (SALDVI) is that they can be used to embed in-situ micro-sensors within macro-components. A single-point SiC/C thermocouple sensor embedded within a SiC macro-component and electrically insulated with silicon nitride layers has been demonstrated. In many applications, multi-point sensors within a single component are needed, e.g., in monitoring the temperature gradient and distribution at different positions. In this paper, multi-point thermocouple devices are demonstrated. The macro-component is a SiC bulk shape made by infiltrating vapor deposited silicon carbide into a silicon carbide powder bed using the SALDVI technique. Multiple SiC/C thermocouples are embedded in-situ in the SiC bulk shape using the SALD technique. The transient and steady state responses ofthe embedded thermocouples are compared to reference thermocouples probing the surfaces of the bulk shape.Mechanical Engineerin