Effect of microstructure and temperature on the erosion rates and mechanisms of modified EB PVD TBCs

Thermal barrier coatings (TBCs) have now been used in gas turbine engines for a number of decades and are now considered to be an accepted technology. As there is a constant drive to increase the turbine entry temperature, in order to increase engine efficiency, the coatings operate in increasingly hostile environments. Thus there is a constant drive to both increase the temperature capabilities of TBCs while at the same time reducing their thermal conductivities. The thermal conductivity of standard 7 wt% yttria stabilized zirconia (7YSZ) electron beam (EB) physical vapour deposited (PVD) TBCs can be reduced in two ways: the first by modification of the microstructure of the TBC and the second by addition of ternary oxides. By modifying the microstructure of the TBC such that there are more fine pores, more photon scattering centres are introduced into the coatings, which reduce the heat transfer by radiation. While ternary oxides will introduce lattice defects into the coating, which increases the phonon scattering, thus reducing the thermal conductivity via lattice vibrations. Unfortunately, both of these methods can have a negative effect on the erosion resistance of EB PVD TBCs. This paper compares the relative erosion rates of ten different EB PVD TBCs tested at 90à ° impact at room temperature and at high temperature and discusses the results in term of microstructural and temperature effects. It was found that by modifying the coating deposition, such that a low density coating with a highly â  featheredâ  microstructure formed, generally resulted in an increase in the erosion rate at room temperature. When there was a significant change between the room temperature and the high temperature erosion mechanism it was accompanied by a significant decrease in the erosion rate, while additions of dopents was found to significantly increase the erosion rate at room and high temperature. However, all the modified coatings still had a lower erosion rate than a plasma sprayed coatings. So, although, relative to a standard 7YSZ coating, the modified coatings have a lower erosion resistance, they still perform better than PS TBCs and their lower thermal conductivities could make them viable alternatives to 7YSZ for use in gas turbine en

Oxidative stress and antioxidant defense mechanisms linked to exercise during cardiopulmonary and metabolic disorders

Oxidative stress has been implicated in the pathophysiology of multiple human diseases, in addition to the aging process. Although various stimuli exist, acute exercise is known to induce a transient increase in reactive oxygen and nitrogen species (RONS), evident by several reports of increased oxidative damage following acute bouts of aerobic and anaerobic exercise. Although the results are somewhat mixed and appear disease dependent, individuals with chronic disease experience an exacerbation in oxidative stress following acute exercise when compared to healthy individuals. However, this increased oxidant stress may serve as a necessary “signal” for the upregulation in antioxidant defenses, thereby providing protection against subsequent exposure to prooxidant environments within susceptible individuals. Here we present studies related to both acute exercise-induced oxidative stress in those with disease, in addition to studies focused on adaptations resulting from increased RONS exposure associated with chronic exercise training in persons with disease

Effect of eicosapentaenoic and docosahexaenoic acid on resting and exercise-induced inflammatory and oxidative stress biomarkers: a randomized, placebo controlled, cross-over study

<p>Abstract</p> <p>Background</p> <p>The purpose of the present investigation was to determine the effects of EPA/DHA supplementation on resting and exercise-induced inflammation and oxidative stress in exercise-trained men. Fourteen men supplemented with 2224 mg EPA+2208 mg DHA and a placebo for 6 weeks in a random order, double blind cross-over design (with an 8 week washout) prior to performing a 60 minute treadmill climb using a weighted pack. Blood was collected pre and post exercise and analyzed for a variety of oxidative stress and inflammatory biomarkers. Blood lactate, muscle soreness, and creatine kinase activity were also measured.</p> <p>Results</p> <p>Treatment with EPA/DHA resulted in a significant increase in blood levels of both EPA (18 ± 2 μmol·L^-1vs. 143 ± 23 μmol·L^-1; p < 0.0001) and DHA (67 ± 4 μmol·L^-1vs. 157 ± 13 μmol·L^-1; p < 0.0001), while no differences were noted for placebo. Resting levels of CRP and TNF-α were lower with EPA/DHA compared to placebo (p < 0.05). Resting oxidative stress markers were not different (p > 0.05). There was a mild increase in oxidative stress in response to exercise (XO and H₂O₂) (p < 0.05). No interaction effects were noted. However, a condition effect was noted for CRP and TNF-α, with lower values with the EPA/DHA condition.</p> <p>Conclusion</p> <p>EPA/DHA supplementation increases blood levels of these fatty acids and results in decreased resting levels of inflammatory biomarkers in exercise-trained men, but does not appear necessary for exercise-induced attenuation in either inflammation or oxidative stress. This may be due to the finding that trained men exhibit a minimal increase in both inflammation and oxidative stress in response to moderate duration (60 minute) aerobic exercise.</p

Combining statistics from two national complex surveys to estimate injury rates per hour exposed and variance by activity in the USA

BACKGROUND: A common issue in descriptive injury epidemiology is that in order to calculate injury rates that account for the time spent in an activity, both injury cases and exposure time of specific activities need to be collected. In reality, few national surveys have this capacity. To address this issue, we combined statistics from two different national complex surveys as inputs for the numerator and denominator to estimate injury rate, accounting for the time spent in specific activities and included a procedure to estimate variance using the combined surveys. METHODS: The 2010 National Health Interview Survey (NHIS) was used to quantify injuries, and the 2010 American Time Use Survey (ATUS) was used to quantify time of exposure to specific activities. The injury rate was estimated by dividing the average number of injuries (from NHIS) by average exposure hours (from ATUS), both measured for specific activities. The variance was calculated using the \u27delta method\u27, a general method for variance estimation with complex surveys. RESULTS: Among the five types of injuries examined, \u27sport and exercise\u27 had the highest rate (12.64 injuries per 100 000 h), followed by \u27working around house/yard\u27 (6.14), driving/riding a motor vehicle (2.98), working (1.45) and sleeping/resting/eating/drinking (0.23). The results show a ranking of injury rate by activity quite different from estimates using population as the denominator. CONCLUSIONS: Our approach produces an estimate of injury risk which includes activity exposure time and may more reliably reflect the underlying injury risks, offering an alternative method for injury surveillance and research

Adaptive-Aggressive Traders Don't Dominate

For more than a decade Vytelingum's Adaptive-Aggressive (AA) algorithm has been recognized as the best-performing automated auction-market trading-agent strategy currently known in the AI/Agents literature; in this paper, we demonstrate that it is in fact routinely outperformed by another algorithm when exhaustively tested across a sufficiently wide range of market scenarios. The novel step taken here is to use large-scale compute facilities to brute-force exhaustively evaluate AA in a variety of market environments based on those used for testing it in the original publications. Our results show that even in these simple environments AA is consistently out-performed by IBM's GDX algorithm, first published in 2002. We summarize here results from more than one million market simulation experiments, orders of magnitude more testing than was reported in the original publications that first introduced AA. A 2019 ICAART paper by Cliff claimed that AA's failings were revealed by testing it in more realistic experiments, with conditions closer to those found in real financial markets, but here we demonstrate that even in the simple experiment conditions that were used in the original AA papers, exhaustive testing shows AA to be outperformed by GDX. We close this paper with a discussion of the methodological implications of our work: any results from previous papers where any one trading algorithm is claimed to be superior to others on the basis of only a few thousand trials are probably best treated with some suspicion now. The rise of cloud computing means that the compute-power necessary to subject trading algorithms to millions of trials over a wide range of conditions is readily available at reasonable cost: we should make use of this; exhaustive testing such as is shown here should be the norm in future evaluations and comparisons of new trading algorithms.Comment: To be published as a chapter in "Agents and Artificial Intelligence" edited by Jaap van den Herik, Ana Paula Rocha, and Luc Steels; forthcoming 2019/2020. 24 Pages, 1 Figure, 7 Table

Does \u2018bigger\u2019mean \u2018better\u2019? Pitfalls and shortcuts associated with big data for social research

\u2018Big data is here to stay.\u2019 This key statement has a double value: is an assumption as well as the reason why a theoretical reflection is needed. Furthermore, Big data is something that is gaining visibility and success in social sciences even, overcoming the division between humanities and computer sciences. In this contribution some considerations on the presence and the certain persistence of Big data as a socio-technical assemblage will be outlined. Therefore, the intriguing opportunities for social research linked to such interaction between practices and technological development will be developed. However, despite a promissory rhetoric, fostered by several scholars since the birth of Big data as a labelled concept, some risks are just around the corner. The claims for the methodological power of bigger and bigger datasets, as well as increasing speed in analysis and data collection, are creating a real hype in social research. Peculiar attention is needed in order to avoid some pitfalls. These risks will be analysed for what concerns the validity of the research results \u2018obtained through Big data. After a pars distruens, this contribution will conclude with a pars construens; assuming the previous critiques, a mixed methods research design approach will be described as a general proposal with the objective of stimulating a debate on the integration of Big data in complex research projecting

Effect of the dietary supplement Meltdown on catecholamine secretion, markers of lipolysis, and metabolic rate in men and women: a randomized, placebo controlled, cross-over study

<p>Abstract</p> <p>Background</p> <p>We have recently reported that the dietary supplement Meltdown^®increases plasma norepinephrine (NE), epinephrine (EPI), glycerol, free fatty acids (FFA), and metabolic rate in men. However, in that investigation measurements ceased at 90 minutes post ingestion, with values for blood borne variables peaking at this time. It was the purpose of the present investigation to extend the time course of measurement to 6 hours, and to include women within the design to determine if sex differences to treatment exist.</p> <p>Methods</p> <p>Ten men (24 ± 4 yrs) and 10 women (22 ± 2 yrs) ingested Meltdown^®or a placebo, using a randomized, cross-over design with one week separating conditions. Blood samples were collected immediately before supplementation and at one hour intervals through 6 hours post ingestion. A standard meal was provided after the hour 3 collection. Samples were assayed for EPI, NE, glycerol, and FFA. Five minute breath samples were collected at each time for measurement of metabolic rate and substrate utilization. Area under the curve (AUC) was calculated. Heart rate and blood pressure were recorded at all times. Data were also analyzed using a 2 (sex) × 2 (condition) × 7 (time) repeated measures analysis of variance, with Tukey <it>post hoc </it>testing.</p> <p>Results</p> <p>No sex × condition interactions were noted for AUC for any variable (p > 0.05). Hence, AUC data are collapsed across men and women. AUC was greater for Meltdown^®compared to placebo for EPI (367 ± 58 pg·mL^-1·6 hr^-1vs. 183 ± 27 pg·mL^-1·6 hr^-1; p = 0.01), NE (2345 ± 205 pg·mL^-1·6 hr^-1vs. 1659 ± 184 pg·mL^-1·6 hr^-1; p = 0.02), glycerol (79 ± 8 μg·mL^-1·6 hr^-1vs. 59 ± 6 μg·mL^-1·6 hr^-1; p = 0.03), FFA (2.46 ± 0.64 mmol·L^-1·6 hr^-1vs. 1.57 ± 0.42 mmol·L^-1·6 hr^-1; p = 0.05), and kilocalorie expenditure (439 ± 26 kcal·6 hrs^-1vs. 380 ± 14 kcal·6 hrs^-1; p = 0.02). No effect was noted for substrate utilization (p = 0.39). Both systolic and diastolic blood pressure (p < 0.0001; 1–16 mmHg), as well as heart rate (p = 0.01; 1–9 bpm) were higher for Meltdown^®. No sex × condition × time interactions were noted for any variable (p > 0.05).</p> <p>Conclusion</p> <p>Ingestion of Meltdown^®results in an increase in catecholamine secretion, lipolysis, and metabolic rate in young men and women, with a similar response for both sexes. Meltdown^®may prove to be an effective intervention strategy for fat loss, assuming individuals are normotensive and their treatment is monitored by a qualified health care professional.</p

On the correspondence between surface UV observations and TOMS determinations of surface UV: a potential method for quality evaluating world surface UV observations

A comparison of erythemally weighted surface UV irradiance observations with similar NASA TOMS surface UV determinations is described. Comparisons are made for two observation periods: the Robertson-Berger (R-B) meter period from 1974 to the late 1980s and the current period from 1996 to the present when more sophisticated UVB-1 instruments were used. The more primitive R-B meter observations that comprised the fi rst U.S. UV network are seen to drift downward with respect to those of the TOMS. While the UVB-1 observations did not appear to drift, a substantial bias is noted to exist between the TOMS and the UVB-1 stations collecting observations; the TOMS estimations tend to be higher. A portion of the bias may be attributed to errors in calibration, total ozone, and cosine response of the surface instrumentation. Unaccounted aerosol effects, although not considered to be large in the TOMS estimations, present another source of error. Comparisons are fi rst done for all sky conditions and then for clear sky conditions. The biases typically agree for all sky conditions within the uncertainties of the surface instruments' calibrations, liberally defi ned as ± 5%, implying that the TOMS cloud correction scheme performs reasonably well. Snow cover severely impacts the TOMS observations, giving considerably higher estimations. The biases for clear sky conditions ranged from 15% to 19% with no obvious drifts between the satellite and surface observations. The variation in the biases among stations is within the calibration uncertainties of the instruments, but the absolute bias is unexpectedly large. The standard deviations of the clear sky comparisons among all stations are steady at 4.8% ± 0.7%. A plot of the TOMS/UVB-1 ratio versus TOMS cloud refl ectivity observations is noisy, but qualitatively suggestive of a possible slight increase (~ 5% or greater) over the range of clear to overcast skies. The results from these comparisons is believed to be relevant to a WMO goal of uniformly assuring the quality of UV observations made by networks in many countries. The results for clear sky comparisons suggest that a satellite observing system such as TOMS, which provides global coverage daily, might partially serve as a fi rst-order check to quality assure UV observations being made by networks worldwide. Future research should concentrate on determining the causes of the large differences seen between the UVB-1 and TOMS and the range of uncertainties, using a larger array of stations