60 research outputs found
Effects of buffer loading for electrospray ionization mass spectrometry of a noncovalent protein complex that requires high concentrations of essential salts
Investigation of the initial fragmentation of oligodeoxynucleotides in a quadrupole ion trap: Charge level-related base loss
Stability of the homopentameric b subunits of shiga toxins 1 and 2 in solution and the gas phase as revealed by nanoelectrospray fourier transform ion cyclotron resonance mass spectrometry
Power Analysis of Field-Based Bicycle Motor Cross (BMX)
Introduction: Power meter is a useful tool for monitoring cyclistsâ training and race
performance. However, limited data are available regarding BMX racing power output.
The aim of this study was to characterise the power production of BMX riders and
investigate its potential role on race performance.
Methods: Fourteen male riders (age: 20.3 ± 1.5 years, height: 1.75 ± 0.05 m, mass: 70.2 ±
6.4 kg) participated in this study. The tests consist of performing two races apart from 15-min
recovery. SRM power meter was used to record power and cadence. Cyclistsâ fastest race
was used for the data analysis. Heart rate was recorded at 1-s intervals using a Garmin HR
chest strap. Lap time was recorded using four pairs of photocells positioned at the start gate,
bottom of the start ramp, end of first corner (time cornering), and on the finish line.
Results: There was a large correlation between race time and relative peak power (r = â0.68,
p < 0.01) as well as average power with zero value excluded (r = â0.52, p < 0.01). Race time
was also significantly associated with time cornering (r = 0.58, p < 0.01). Peak power
(1288.7 ± 62.6 W) was reached in the first 2.34 second of the race. With zero values
included, the average power was 355.8 ± 25.4 W, which was about 28% of the peak
power, compared to 62% when zero values were excluded (795.6 ± 63.5 W).
Conclusion: The post-race analysis of the power data might help the cyclists recognizing
the need to apply certain strategies on pedalling rates and power production in certain
portions of the BMX track, specially, at the start and around the first corner. BMX coaches
must consider designing training programs based on the race intensity and power output
zones
Prediction of track performance in competitive BMX riders using laboratory measures
Identifying key physiological factors is essential in cycling; however, the unique nature of BMX decreases the validity and transferability of research findings from other cycling disciplines. Therefore, this study highlighted the physical and physiological characteristics of BMX riders that could influence track performance. Fifteen sub-elite BMX riders (male n = 12; age 18.3 ± 3.3 and female n = 3; 17.7 ± 5.7 years) undertook a battery of laboratory tests on three different occasions, including body composition, upper and lower body strength, flexibility, sprint and aerobic capacity measures. On a separate day, participants completed three full lap sprints on an outdoor BMX track. Correlation and multiple linear regression analyses were performed to develop predictive models of performance across the laboratory tests and race time. The final model indicated power to weight ratio, relative back-leg-chest strength and arm span explained ~87% of the variability in finish time (adjusted R2 = 0.87, p < .01). These findings highlighted the importance of a multidimensional approach for developing BMX race performance. Coaches should prioritise these variables in their training programs and selection of future talents.
However, further physiological and biomechanical investigation is needed to validate current findings, particularly among elite riders
The role of smelter emissions and element remobilization in the sediment chemistry of 99 lakes around the Horne smelter, Quebec
Ninety-nine lakes were sampled at varying distances up to 75 km from the Horne smelter at Rouyn-Noranda, Quebec, to study the influence of the smelter versus other factors on metal concentrations in lake sediments. Most of these lakes he within the Abitibi Greenstone Belt, a zone of extensive base metal and gold mineralization and the focus of a mining and smelting economy for almost a century. Lake sediment cores, c. 25 cm long, were collected and sampled at the top (0-2 cm) and the bottom (18-20 cm) to capture sediment that was deposited after the smelter was in operation ('post-industrial') and well before the mining and smelting activity was started ('pre-industrial'). Additionally, nine cores were sampled in 1 cm increments to depths of up to 50 cm to study temporal patterns and potential element remobilization in detail. The cores were analysed for an extensive suite of elements. This paper focuses on those elements that are emitted by the smelter for which there are records of emissions through time, namely As, Cd, Cu, Pb and Zn. A spatial statistical approach - a logistic model of metal content versus distance from the smelter - was used investigate the relationship of sediment chemistry with smelter emissions and other possible influences. Using Cu as a representative proxy for the other emitted metals, this analysis demonstrates that elements are enriched in lake sediments by a factor of about three times around the smelter, that the impact of the smelter is detectable in lakes to a distance of at least 50 km, and that there is no obvious association between sediment Cu concentration and bedrock geology, land-use, lake pH, or lake morphometry Oake area/lake catchment area). The nine lakes studied in detail show enrichment towards the sediment-water interface (SWI) and relatively steady concentrations below depths of c. 10 cm. However, depth profiles do not match changes in the magnitude of smelter emissions through time, nor do they match changes in emission chemistry (element ratios) through time. Element ratios do generally move towards the chemistry of the emissions, suggesting smelter influence, but do not do so predictably. For example, (i) trends in the Cu/Pb ratio continue to the very bottom of cores into material deposited hundreds of years before industrialization, and (ii) proximity to the smelter does not lead to greater similarity between sediment and emission chemistry. These results suggest that significant element remobilization is occurring and that it differs from lake to lake and from element to element. We conclude that lakes within 50 km of the smelter have elevated metal concentrations in their near-surface sediments due to stack emissions but, due to element cycling and mobility, it is difficult to quantitatively determine the magnitude of metal increase attributable to the smelter. We also suggest that due to upward remobilization, the duration of industrial metal enrichments in surface sediments (the residence time) may be increased, thereby making surface enrichments more persistent than would be predicted by the sedimentation rate.64170018720
Canadian Prairie Rangeland and Seeded Forage Classification Using Multiseason Landsat 8 and Summer RADARSAT-2
Rangeland and seeded forage in Canada's Prairie provinces represent productive landscapes that provide multiple ecosystem services. Past efforts to map these resources at regional scales have not achieved consistently high accuracies as they are spatially variable in both ecology and management. In particular, Agriculture and Agri-food Canada needs to distinguish these land use classes from each other and from cropland in its annual national agricultural land cover inventory. Given the potential to distinguish these classes based on seasonal phenological differences, this study used multi-season Landsat 8 top-of-atmosphere reflectance data and derived vegetation and phenological indices, as well as mid-summer RADARSAT-2 data in random forest classification of two ecoregions in Alberta and Manitoba. Classification accuracy was compared for single and multi-date Landsat 8 variables, the vegetation index and phenological variable groups, RADARSAT-2 VV and VH backscatter intensity, and combined datasets. Variable importance analysis showed that spring Landsat 8 reflectance generally contributed most to class discrimination, but accuracy improved with the addition of Landsat 8 data from the other seasons. Vegetation indices and phenological variables produced similar accuracies and were deemed to not warrant the additional processing effort to derive them. RADARSAT-2 VH backscatter was the most important variable for the Manitoba study area, which is wetter with more vegetation structure variability than the Alberta study area. Bac
Cycloaddition reactions of azides and electron-deficient alkenes in deep eutectic solvents: pyrazolines, aziridines and other surprises
The reaction of organic azides and electronâdeficient alkenes was investigated in a deep eutectic solvent. A series of highly substituted 2âpyrazolines was successfully isolated and their formation rationalised by DFT calculations. The critical effect of substitution was also explored; even relatively small changes in the cycloaddition partners led to completely different reaction outcomes and triazolines, triazoles or enaminones can be formed as major products depending on the alkene employed
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