NIRS Measurements with Elite Speed Skaters: Comparison Between the Ice Rink and the Laboratory

Wearable, wireless near-infrared (NIR) spectrometers were used to compare changes in on-ice short-track skating race simulations over 1,500 m with a 3-min cycle ergometry test at constant power output (400 W). The subjects were six male elite short-track speed skaters. Both protocols elicited a rapid desaturation (∆TSI%) in the muscle during early stages (initial 20 s); however, asymmetry between right and left legs was seen in ΔTSI% for the skating protocol, but not for cycling. Individual differences between skaters were present in both protocols. Notably, one individual who showed a relatively small TSI% change (-10.7%, group mean = -26.1%) showed a similarly small change during the cycling protocol (-5.8%, group mean = -14.3%). We conclude that NIRS-detected leg asymmetry is due to the specific demands of short-track speed skating. However, heterogeneity between individuals is not specific to the mode of exercise. Whether this is a result of genuine differences in physiology or a reflection of differences in the optical properties of the leg remains to be determined

Examining the Personal and Institutional Determinants of Research Productivity in Hospitality and Tourism Management

The transition toward a post-capitalist knowledge-oriented economy has resulted in an increasingly competitive academic environment, where the success of faculty is dependent on their research productivity. This study examines the personal and institutional determinants of the quantity and quality of the research productivity of hospitality and tourism management faculty in US institutions. A survey of 98 faculty found that a different set of determinants impact the quantity and quality aspects of research productivity. Also, institutional determinants were found to play a larger role, indicating the need for administrators to strive for a culture that is supportive of and an infrastructure that is conducive to their faculty’s research success. The authors use the field of hospitality and tourism management as a case study to develop a holistic and cohesive framework for knowledge worker productivity that can guide the evaluation, hiring, and development of researchers

Low-cycle fatigue of Type 347 stainless steel and Hastelloy alloy X in hydrogen gas and in air at elevated temperatures

An investigation was conducted to assess the low-cycle fatigue resistance of two alloys, Type 347 stainless steel and Hastelloy Alloy X, that were under consideration for use in nuclear-powered rocket vehicles. Constant-amplitude, strain-controlled fatigue tests were conducted under compressive strain cycling at a constant strain rate of 0.001/sec and at total axial strain ranges of 1.5, 3.0, and 5.0 %, in both laboratory-air and low-pressure hydrogen-gas environments at temperatures from 538 to 871 C. Specimens were obtained from three heats of Type 347 stainless steel bar and two heats of Hastelloy Alloy X. The tensile properties of each heat were determined at 21, 538, 649, and 760 C. The continuous cycling fatigue resistance was determined for each heat at temperatures of 538, 760, and 871 C. The Type 347 stainless steel exhibited equal or superior fatigue resistance to the Hastelloy Alloy X at all conditions of this study

Electrochemical Evaluation of Constituent Intermetallics in Aluminum Alloy 2024-T3 Exposed to Aqueous Vanadate Inhibitors

Experiments were conducted to determine how inhibiting forms of vanadate interact with complex Al alloy microconstituent intermetallics to impart corrosion protection. Cathodic polarization experiments on Al 2024-T3 indicate a strong correlation between inhibition and the presence of tetrahedrally coordinated vanadate. Anodic and cathodic polarization curves were measured on bulk synthesized Al_2Cu, Al_2CuMg, Al_7Cu_2Fe, and Al_20Cu_2Mn_3 in alkaline 0.5 M NaCl solutions with and without 10 mM NaVO_3. Vanadate additions generally decreased E_corr, increased E_pit, and decreased the cathodic kinetics of all tested materials. Because of decreased cathodic kinetics, open-circuit potentials (OCPs) were shifted in the active direction in aerated solutions when vanadate was present. This shift pins the OCP just below the observed pitting potential for Al_2CuMg in vanadate solution, effectively preventing breakdown and subsequent support of rapid oxygen reduction by Cu-enriched clusters. E_corr, E_pit, E_rp, i_corr, i_pass, and i at −1.3 V_SCE data from polarization experiments were summarized in cumulative distribution plots, and averages are presented in tabulated format. Scanning electron microscopy images of Al 2024-T3 used for 4 h of OCP measurement show that vanadate greatly decreased circumferential trenching around intermetallic particles in both aerated and deaerated solutions. Potentiostatic hold experiments were used to show suppression of Al_2CuMg dissolution in vanadate solutions

Corrosion Inhibition of Aluminum Alloy 2024-T3 by Aqueous Vanadium Species

Nuclear magnetic resonance (NMR) measurements were made on aqueous vanadate solutions to characterize speciation as a function of pH and vanadate concentration. Additionally, potentiodynamic polarization measurements were carried out on Al alloy 2024-T3 in 50 mM NaCl solutions in which pH and vanadate concentration were systematically varied. Results showed that inhibition by vanadates occurred mainly in alkaline solutions where tetrahedrally coordinated vanadates, metavanadate and pyrovanadate, were abundant. Inhibition was not observed in solutions where octahedrally coordinated decavanadates predominated. Anodic inhibition, in the form of increased pitting potential, was observed in both aerated and deaerated solutions. In contrast, cathodic inhibition was observed only in aerated solutions acting primarily through the suppression of oxygen reduction. Energy-dispersive spectroscopy, used to collect chemical maps from aluminum coupons exposed to vanadate solutions, showed the suppression of Al_2CuMg particle dissolution compared to vanadate-free solutions. NMR measurements were also used to track changes in vanadate speciation with time, pH adjustment, and with exposure to metallic aluminum surfaces. NMR showed noninhibiting octahedrally coordinated decavanadates rapidly decompose into inhibiting tetrahedrally coordinated metavanadates and pyrovanadates after alkaline pH adjustment. While decomposition begins immediately upon pH adjustment, equilibrium may not be reached even after significant time periods

Monitoring Fatigue During the In-Season Competitive Phase in Elite Soccer Players.

Purpose:To quantify the relationship between daily training load and a range of potential measures of fatigue in elite soccer players during an in-season competitive phase (17 d).Methods:Total high-intensity-running (THIR) distance, perceived ratings of wellness (fatigue, muscle soreness, sleep quality), countermovement-jump height (CMJ), postexercise heart-rate recovery (HRR), and heart-rate variability (Ln rMSSD) were analyzed during an in-season competitive period (17 d). General linear models were used to evaluate the influence of daily fluctuation in THIR distance on potential fatigue variables.Results:Fluctuations in fatigue (r = −.51, large, P &lt; .001), Ln rMSSD (r = −.24, small, P = .04), and CMJ (r = .23, small, P = .04) were significantly correlated with fluctuations in THIR distance. Correlations between variability in muscle soreness, sleep quality, and HRR and THIR distance were negligible and not statistically significant.Conclusions:Perceived ratings of fatigue and Ln rMSSD were sensitive to daily fluctuations in THIR distance in a sample of elite soccer players. Therefore, these particular markers show promise as simple, noninvasive assessments of fatigue status in elite soccer players during a short in-season competitive phase.</jats:sec

Interpreting physical performance in professional soccer match-play: Should we be more pragmatic in our approach?

Academic and practitioner interest in the physical performance of male professional soccer players in the competition setting determined via time-motion analyses has grown substantially over the last four decades leading to a substantial body of published research and aiding development of a more systematic evidence-based framework for physical conditioning. Findings have forcibly shaped contemporary opinions in the sport with researchers and practitioners frequently emphasising the important role that physical performance plays in match outcomes. Time-motion analyses have also influenced practice as player conditioning programmes can be tailored according to the different physical demands identified across individual playing positions. Yet despite a more systematic approach to physical conditioning, data indicate that even at the very highest standards of competition, the contemporary player is still susceptible to transient and end-game fatigue. Over the course of this article, the author suggests that a more pragmatic approach to interpreting the current body of time-motion analysis data and its application in the practical setting is nevertheless required. Examples of this are addressed using findings in the literature to examine: a) the association between competitive physical performance and ‘success’ in professional soccer, b) current approaches to interpreting differences in time-motion analysis data across playing positions and, c) whether data can realistically be used to demonstrate the occurrence of fatigue in match-play. Gaps in the current literature and directions for future research are also identified

Characterization of shape memory alloys for safety mechanisms.

Shape memory alloys (SMAs) are metals that exhibit large recoverable strains and exert large forces with tremendous energy densities. The behavior of SMAs is thermomechanically coupled. Their response to temperature is sensitive to their loading condition and their response to loading is sensitive to their thermal condition. This coupled behavior is not to be circumvented, but to be confronted and understood, since it is what manifests SMA's superior clamping performance. To reasonably characterize the coupled behavior of SMA clamping rings used in safety mechanisms, we conduct a series of experiments on SMA samples. The results of the tests will allow increased fidelity in modeling and failure analysis of parts

Non-traditional solution routes to ferroelectric materials

Non-traditional precursor solutions for production of ferroelectric thin films have been developed for PXZT (X = L, N, S), SBT, and PMN systems. For PXZT and SBT, pyridine is a key solvent, wherein, it both solubilizes and reduces the reactivity of the individual components of the solution. Further control of the final films has been obtained using novel tailor-made precursors to dictate their properties