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Sample records for net vo2 ml

  1. Pulmonary and leg VO2 during submaximal exercise: implications for muscular efficiency

    Science.gov (United States)

    Poole, D. C.; Gaesser, G. A.; Hogan, M. C.; Knight, D. R.; Wagner, P. D.

    1992-01-01

    Insights into muscle energetics during exercise (e.g., muscular efficiency) are often inferred from measurements of pulmonary gas exchange. This procedure presupposes that changes of pulmonary O2 (VO2) associated with increases of external work reflect accurately the increased muscle VO2. The present investigation addressed this issue directly by making simultaneous determinations of pulmonary and leg VO2 over a range of work rates calculated to elicit 20-90% of maximum VO2 on the basis of prior incremental (25 or 30 W/min) cycle ergometry. VO2 for both legs was calculated as the product of twice one-leg blood flow (constant-infusion thermodilution) and arteriovenous O2 content difference across the leg. Measurements were made 3-5 min after each work rate imposition to avoid incorporation of the VO2 slow component above the lactate threshold. For all 17 subjects, the slope of pulmonary VO2 (9.9 +/- 0.2 ml O2.W-1.min-1) was not different (P greater than 0.05) from that for leg VO2 (9.2 +/- 0.6 ml O2.W-1.min-1). Estimation of "delta" efficiency (i.e., delta work accomplished divided by delta energy expended, calculated from slope of VO2 vs. work rate and a caloric equivalent for O2 of 4.985 cal/ml) using pulmonary VO2 measurements (29.1 +/- 0.6%) was likewise not significantly different (P greater than 0.05) from that made using leg VO2 measurements (33.7 +/- 2.4%). These data suggest that the net VO2 cost of metabolic "support" processes outside the exercising legs changes little over a relatively broad range of exercise intensities. Thus, under the conditions of this investigation, changes of VO2 measured from expired gas reflected closely those occurring within the exercising legs.

  2. Relationship between %HRmax, %HR reserve, %VO2max, and %VO2 reserve in elite cyclists.

    Science.gov (United States)

    Lounana, Joseph; Campion, Frederic; Noakes, Timothy D; Medelli, Jean

    2007-02-01

    To evaluate the relations between %HRmax, %HRR, %VO2max, and %VO2R in elite cyclists and to check whether the intensity scale recommended by ACSM in its 1998 position stand is also applicable to this specific population. Twenty-six male elite road cyclists (25.1 +/- 0.7 yr, 71.0 +/- 1.2 kg, 70.9 +/- 1.2 mL x kg(-1) x min(-1), 433.9 +/- 9.8 W) performed an incremental maximal exercise test (50 W x 3 min(-1)). Individual linear regressions based on HR and VO2 values measured at rest, end of each stage, and maximum, were used to calculate slopes and intercepts, and to predict %HRmax, %HRR, %VO2max, or %VO2R for a given exercise intensity. Below 85% VO2max or VO2R, predicted %HRmax values were significantly higher (P VO2max, and 48, 61, 74% vs 35, 55, and 70% HRmax at 20, 40, and 60% VO2R). The %HRR versus %VO2max regression mean slope (1.069 +/- 0.01) and intercept (-5.747 +/- 0.80) were significantly different (P VO2max was equivalent to %HRR at and above 75%HRR, and it was significantly higher at (P VO2max. Thus, elite cyclists should use %HRR in relation to %VO2R rather than in relation to %VO2max.

  3. VO2max, protocol duration, and the VO2 plateau.

    Science.gov (United States)

    Yoon, Byung-Kon; Kravitz, Len; Robergs, Robert

    2007-07-01

    The purpose of this study was to compare VO2max, VO2-time slopes at the end of the protocol (last 30 s), and the presence of a VO2 plateau (VO2-time slope VO2max. Eight male (23.8 +/- 3.2 yr) and eight female (26.0 +/- 8.9 yr) subjects of moderate to high fitness levels participated in the study. VO2max was significantly higher in men than in women for each protocol duration, with main effect means of 4.23 versus 2.84 L.min(-1), respectively. For women, VO2max did not differ between any protocol duration. For men, VO2max for the 8-min protocol (4.44 +/- 0.39 L.min(-1)) was significantly higher than for all other protocol durations. Analysis of covariance, using the highest VO2max as the covariate, removed all protocol-duration significance for men. The VO2 slope for the final 30 s of each test was significantly lower for the 16-min protocol compared with the 5-min protocol, for both men and women. The ventilation threshold across four protocols was similar, at approximately 76% of VO2max for both men and women. The protocol duration of tests to VO2max should be between 8 and 10 min for healthy, moderately to highly trained subjects.

  4. VO2 responses to running speeds above VO2max.

    Science.gov (United States)

    Duffield, R; Bishop, D

    2008-06-01

    This study compared VO2, heart rate (HR) and electromyographic (iEMG) responses to speeds above the velocity associated with VO2max (v-VO2max). Eight male, middle-distance runners performed a graded exercise test to determine VO2max and v-VO2max and runs to fatigue at 100 % and 110 % v-VO2max. Breath-by-breath VO2 and HR were continuously recorded; lactate [La (-)] measured pre- and post-run and iEMG measures of rectus femoris (RF) and vastus lateralis were recorded during the first and last 20 s of each run. Analysis indicated longer time to fatigue in the 100 % v-VO2max run with no differences between conditions for VO2 or HR amplitudes or post-run [La (-)] (p > 0.05). There were significantly faster tau values (p VO2max attained. This may potentially be as a result of an increased muscle fibre recruitment stimulus during the faster running velocity resulting in faster cardiodynamic responses.

  5. Time at VO2max during intermittent treadmill running: test protocol dependent or methodological artefact?

    Science.gov (United States)

    Midgley, A W; McNaughton, L R; Carroll, S

    2007-11-01

    Effects of methodological differences on the determination of time at VO (2max) (t (VO2max)) during intermittent treadmill running were investigated. Subjects performed three incremental tests to volitional exhaustion: a continuous protocol with 1-min stages (Cont-INC ([1-min])), and two discontinuous protocols of 2-min (Dis-INC ([2-min])) and 3-min (Dis-INC ([3-min])) stage durations. For each test, VO (2max) and the running velocity associated with V.O (2max) (vVO (2max)) were determined. On a fourth visit, subjects performed an intermittent test with 30-s work and relief intervals run at 105 % and 60 %, respectively, of the vV. (2max) determined during Cont-INC ((1-min)). The t (VO2max) during the intermittent test was determined using three different criteria: VO (2) data points > or = 100 % VO (2max) determined in Cont-INC ((1-min)) (t (VO2max[100 %])), > or = 95 % VO (2max) (t (VO2max[95 %])) and > or = VO (2max) minus 2.1 ml . kg (-1) . min (-1) (t (VO2max[- 2.1])). The V.O (2max) means (SD) for Cont-INC ((1-min)), Dis-INC ((2-min)) and Dis-INC ((3-min)) were 4093 (538), 4096 (516), and 3980 (488) mL . min (-1), respectively. The t (VO2max) means (SD) were: t (VO2max(100 %)) 163 (227) s, t (VO2max(95 %)) 418 (439) s, and t (VO2max(- 2.1)) 358 (395) s. All differences in t (V.O2max) were significantly different (p VO2max) due to using V.O (2max) values derived from using different V.O (2) time-averages were significantly different (p < 0.05). Methodological differences should be considered during interpretation of previous studies.

  6. The Effect of Habitual Smoking on VO2max

    Science.gov (United States)

    Wier, Larry T.; Suminski, Richard R.; Poston, Walker S.; Randles, Anthony M.; Arenare, Brian; Jackson, Andrew S.

    2008-01-01

    VO2max is associated with many factors, including age, gender, physical activity, and body composition. It is popularly believed that habitual smoking lowers aerobic fitness. PURPOSE: to determine the effect of habitual smoking on VO2max after controlling for age, gender, activity and BMI. METHODS: 2374 men and 375 women employed at the NASA/Johnson Space Center were measured for VO2max by indirect calorimetry (RER>=1.1), activity by the 11 point (0-10) NASA Physical Activity Status Scale (PASS), BMI and smoking pack-yrs (packs day*y of smoking). Age was recorded in years and gender was coded as M=1, W=0. Pack.y was made a categorical variable consisting of four levels as follows: Never Smoked (0), Light (1-10), Regular (11-20), Heavy (>20). Group differences were verified by ANOVA. A General Linear Models (GLM) was used to develop two models to examine the relationship of smoking behavior on VO2max. GLM #1(without smoking) determined the combined effects of age, gender, PASS and BMI on VO2max. GLM #2 (with smoking) determined the added effects of smoking (pack.y groupings) on VO2max after controlling for age, gender, PASS and BMI. Constant errors (CE) were calculated to compare the accuracy of the two models for estimating the VO2max of the smoking subgroups. RESULTS: ANOVA affirmed the mean VO2max of each pack.y grouping decreased significantly (psmoking exposure increased. GLM #1 showed that age, gender, PASS and BMI were independently related with VO2max (R2 = 0.642, SEE = 4.90, pSmoked, the effects on VO2max from Light and Regular smoking habits were -0.83 and -0.85 ml.kg- 1.min-1 respectively (psmoking on VO2max was -2.56 ml.kg- 1.min-1 (psmoking group in GLM #2 was smaller than the CE s of the smoking group counterparts in GLM #1. CONCLUSIONS: After accounting for the effects of gender, age, PASS and BMI the effect of habitual smoking on reducing VO2max is minimal, about 0.85 ml/kg/min, until the habit exceeds 20 pack.y at which point an additional decrease

  7. Relationship between body and leg VO2 during maximal cycle ergometry

    Science.gov (United States)

    Knight, D. R.; Poole, D. C.; Schaffartzik, W.; Guy, H. J.; Prediletto, R.; Hogan, M. C.; Wagner, P. D.

    1992-01-01

    It is not known whether the asymptotic behavior of whole body O2 consumption (VO2) at maximal work rates (WR) is explained by similar behavior of VO2 in the exercising legs. To resolve this question, simultaneous measurements of body and leg VO2 were made at submaximal and maximal levels of effort breathing normoxic and hypoxic gases in seven trained male cyclists (maximal VO2, 64.7 +/- 2.7 ml O2.min-1.kg-1), each of whom demonstrated a reproducible VO2-WR asymptote during fatiguing incremental cycle ergometry. Left leg blood flow was measured by constant-infusion thermodilution, and total leg VO2 was calculated as the product of twice leg flow and radial arterial-femoral venous O2 concentration difference. The VO2-WR relationships determined at submaximal WR's were extrapolated to maximal WR as a basis for assessing the body and leg VO2 responses. The differences between measured and extrapolated maximal VO2 were 235 +/- 45 (body) and 203 +/- 70 (leg) ml O2/min (not significantly different). Plateauing of leg VO2 was associated with, and explained by, plateauing of both leg blood flow and O2 extraction and hence of leg VO2. We conclude that the asymptotic behavior of whole body VO2 at maximal WRs is a direct reflection of the VO2 profile at the exercising legs.

  8. Artificial neural network-based equation for estimating VO2max from the 20 m shuttle run test in adolescents.

    Science.gov (United States)

    Ruiz, Jonatan R; Ramirez-Lechuga, Jorge; Ortega, Francisco B; Castro-Piñero, José; Benitez, Jose M; Arauzo-Azofra, Antonio; Sanchez, Cristobal; Sjöström, Michael; Castillo, Manuel J; Gutierrez, Angel; Zabala, Mikel

    2008-11-01

    To develop an artificial neural network (ANN)-equation to estimate maximal oxygen uptake (VO(2max)) from 20m shuttle run test (20 mSRT) performance (stage), sex, age, weight, and height in young persons. The 20 mSRT was performed by 193 (122 boys and 71 girls) adolescents aged 13-19 years. All the adolescents wore a portable gas analyzer to measure VO(2) and heart rate during the test. The equation was developed and cross-validated following the ANN mathematical model. The neural net performance was assessed through several error measures. Agreement between the measured VO(2max) and estimated VO(2max) from Léger's and ANN equations were analysed following the Bland and Altman method. The percentage error was 17.13 and 7.38 for Léger and ANN-equation (P<0.001), respectively, and the standard error of the estimate obtained with Léger's equation was 4.27 ml/(kg min), while for the ANN-equation was 2.84 ml/(kg min). A Bland-Altman plot for the measured VO(2max) and Léger-VO(2max) showed a mean difference of 4.9 ml/(kg min) (P<0.001), while the Bland-Altman plot for the measured VO(2max) and ANN-VO(2max) showed a mean difference of 0.5 ml/(kg min) (P=0.654). In the validation sample, the percentage error was 21.08 and 8.68 for Léger and ANN-equation (P<0.001), respectively. In this study, an ANN-based equation to estimate VO(2max) from 20 mSRT performance (stage), sex, age, weight, and height in adolescents was developed and cross-validated. The newly developed equation was shown to be more accurate than Léger's. The proposed model has been coded in a user-friendly spreadsheet.

  9. Comparing VO2max determined by using the relation between heart rate and accelerometry with submaximal estimated VO2max.

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    Tönis, T M; Gorter, K; Vollenbroek-Hutten, M M R; Hermens, H

    2012-08-01

    An exploratory study to identify parameters that can be used for estimating a subject's cardio-respiratory physical fitness level, expressed as VO2max, from a combination of heart rate and 3D accelerometer data. Data were gathered from 41 healthy subjects (23 male, 18 female) aged between 20 and 29 years. The measurement protocol consisted of a sub-maximal single stage treadmill walking test for VO2max estimation followed by a walking test at two different speeds (4 and 5.5 kmh-1) for parameter determination. The relation between measured heart rate and accelerometer output at different walking speeds was used to get an indication of exercise intensity and the corresponding heart rate at that intensity. Regression analysis was performed using general subject measures (age, gender, weight, length, BMI) and intercept and slope of the relation between heart rate and accelerometer output during walking as independent variables to estimate the VO2max. A linear regression model using a combination of the slope and intercept parameters, together with gender revealed the highest percentage of explained variance (R2 = 0.90) and had a standard error of the estimate (SEE) of 2.052 mL O2kg-1min-1 with VO2max. Results are comparable with current commonly used sub-maximal laboratory tests to estimate VO2max. The combination of heart rate and accelerometer data seems promising for ambulant estimation of VO2max-.

  10. Indirect estimation of VO2max in athletes by ACSM's equation: valid or not?

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    Koutlianos, N; Dimitros, E; Metaxas, T; Cansiz, M; Deligiannis, As; Kouidi, E

    2013-04-01

    The purpose of this study was to assess the indirect calculation of VO2max using ACSM's equation for Bruce protocol in athletes of different sports and to compare with the directly measured; secondly to develop regression models predicting VO2 max in athletes. Fifty five male athletes of national and international level (mean age 28.3 ± 5.6 yrs) performed graded exercise test with direct measurement of VO2 through ergospirometric device. Moreover, 3 equations were used for the indirect calculation of VO2max: a) VO2max= (0.2 · Speed) + (0.9 · Speed · Grade) + 3.5 (ACSM running equation), b) regression analysis model using enter method and c) stepwise method based on the measured data of VO2. Age, BMI, speed, grade and exercise time were used as independent variables. Regression analysis using enter method yielded the equation (R=.64, standard error of estimation [SEE] = 6.11): VO2max (ml·kg(-1)·min(-1)) = 58.443 - (0.215 · age) - (0.632 · BMI) - (68.639 · grade) + (1.579 · time) while stepwise method (R = .61, SEE = 6.18) led to: VO2max (ml·kg(-1)·min(-1)) = 33.971 - (0.291 · age) + (1.481 · time). The calculated values of VO2max from these regression models did not differ significantly from the measured VO2max (p>.05). On the contrary, VO2max calculated from the ACSM's running equation was significantly higher from the actually measured value by 14.6% (p VO2max in athletes aged 18-37 years using Bruce protocol. Only the regression models were correlated moderately with the actually measured values of VO2max.

  11. Indirect estimation of VO2max in athletes by ACSM’s equation: valid or not?

    Science.gov (United States)

    Koutlianos, N; Dimitros, E; Metaxas, T; Cansiz, M; Deligiannis, AS; Kouidi, E

    2013-01-01

    Aim: The purpose of this study was to assess the indirect calculation of VO2max using ACSM’s equation for Bruce protocol in athletes of different sports and to compare with the directly measured; secondly to develop regression models predicting VO2 max in athletes. Methods: Fifty five male athletes of national and international level (mean age 28.3 ± 5.6 yrs) performed graded exercise test with direct measurement of VO2 through ergospirometric device. Moreover, 3 equations were used for the indirect calculation of VO2max: a) VO2max= (0.2 · Speed) + (0.9 · Speed · Grade) + 3.5 (ACSM running equation), b) regression analysis model using enter method and c) stepwise method based on the measured data of VO2. Age, BMI, speed, grade and exercise time were used as independent variables. Results: Regression analysis using enter method yielded the equation (R=.64, standard error of estimation [SEE] = 6.11): VO2max (ml·kg-1·min-1) = 58.443 - (0.215 · age) - (0.632 · BMI) - (68.639 · grade) + (1.579 · time) while stepwise method (R = .61, SEE = 6.18) led to: VO2max (ml·kg-1·min-1) = 33.971 - (0.291 · age) + (1.481 · time). The calculated values of VO2max from these regression models did not differ significantly from the measured VO2max (p>.05). On the contrary, VO2max calculated from the ACSM’s running equation was significantly higher from the actually measured value by 14.6% (p VO2max in athletes aged 18-37 years using Bruce protocol. Only the regression models were correlated moderately with the actually measured values of VO2max. PMID:24376318

  12. Monitoring changes in VO2max via the Polar FT40 in female collegiate soccer players.

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    Esco, Michael R; Snarr, Ronald L; Williford, Hank N

    2014-01-01

    This study was conducted to determine if the Polar FT40 could accurately track changes in maximal oxygen consumption (VO2max) in a group of female soccer players. Predicted VO2max (pVO2max) via the Polar FT40 and observed VO2max (aVO2max) from a maximal exercise test on a treadmill were determined for members of a collegiate soccer team (n = 20) before and following an 8-week endurance training protocol. Predicted (VO2max and aVO2max measures were compared at baseline and within 1 week post-training. Change values (i.e., the difference between pre to post) for each variable were also determined and compared. There was a significant difference in aVO2max (pre = 43.6 ± 2.4 ml · kg · min(-1), post = 46.2 ± 2.4 ml · kg · min(-1), P VO2max following 8 weeks of endurance training in female collegiate soccer players.

  13. Evaluation of the American College of Sports Medicine submaximal treadmill running test for predicting VO2max.

    Science.gov (United States)

    Marsh, Clare E

    2012-02-01

    The purpose of this study was to assess the validity of the American College of Sports Medicine's (ACSM's) submaximal treadmill running test in predicting VO2max. Twenty-one moderately well-trained men aged 18-34 years performed 1 maximal treadmill test to determine maximal oxygen uptake (M VO2max) and 2 submaximal treadmill tests using 4 stages of continuous submaximal exercise. Estimated VO2max was predicted by extrapolation to age-predicted maximal heart rate (HRmax) and calculated in 2 ways: using data from all submaximal stages between 110 b·min(-1) and 85% HRmax (P VO2max-All), and using data from the last 2 stages only (P VO2max-2). The measured VO2max was overestimated by 3% on average for the group but was not significantly different to predicted VO2max (1-way analysis of variance [ANOVA] p = 0.695; M VO2max = 53.01 ± 5.38; P VO2max-All = 54.27 ± 7.16; P VO2max-2 = 54.99 ± 7.69 ml·kg(-1)·min(-1)), although M VO2max was not overestimated in all the participants--it was underestimated in 30% of observations. Pearson's correlation, standard error of estimate (SEE), and total error (E) between measured and predicted VO2max were r = 0.646, 4.35, 4.08 ml·kg(-1)·min(-1) (P VO2max-All) and r = 0.642, 4.21, 3.98 ml·kg(-1)·min(-1) (P VO2max-2) indicating that the accuracy in prediction (error) was very similar whether using P VO2max-All or P VO2max-2, with up to 70% of the participants predicted scores within 1 SEE (∼4 ml·kg(-1)·min(-1)) of M VO2max. In conclusion, the ACSM equation provides a reasonably good estimation of VO2max with no difference in predictive accuracy between P VO2max-2 and P VO2max-All, and hence, either approach may be equally useful in tracking an individual's aerobic fitness over time. However, if a precise knowledge of VO2max is required, then it is recommended that this be measured directly.

  14. Comparison of the YMCA and a Custom Submaximal Exercise Test for Determining VO2max.

    Science.gov (United States)

    Jamnick, Nicholas A; By, Savanny; Pettitt, Cherie D; Pettitt, Robert W

    2016-02-01

    The maximal oxygen uptake (VO2max) is deemed the highest predictor for all-cause mortality, and therefore, an ability to assess VO2max is important. The YMCA submaximal test is one of the most widely used tests to estimate VO2max; however, it has questionable validity. We validated a customized submaximal test that accounts for the nonlinear rise in VO2 relative to power output and compared its accuracy against the YMCA protocol. Fifty-six men and women performed a graded exercise test with a subsequent exhaustive, square wave bout for the verification of "true" VO2max. In counterbalanced order, subjects then completed the YMCA test and our new Mankato submaximal exercise test (MSET). The MSET consisted of a 3-min stage estimated at 35% VO2max and a second 3-min stage estimated at either 65% or 70% VO2max, where VO2max was estimated with a regression equation using sex, body mass index, age, and self-reported PA-R. VO2 values from the graded exercise test and square wave verification bout did not differ with the highest value used to identify "true" VO2max (45.1 ± 8.89 mL · kg(-1) · min(-1)). The MSET (43.6 ± 8.6 mL · kg(-1) · min(-1)) did not differ from "true" VO2max, whereas the YMCA test (41.1 ± 9.6 mL · kg(-1) · min(-1)) yielded an underestimation (P = 0.002). The MSET was moderately correlated with "true" VO2max (ICC = 0.73, CV of 11.3%). The YMCA test was poorly correlated with "true" VO2max (ICC = 0.29, CV of 15.1%). To our knowledge, this is the first study to examine submaximal exercise protocols versus a verified VO2max protocol. The MSET yielded better estimates of VO2max because of the protocol including a stage exceeding gas exchange threshold.

  15. A new nonexercise-based VO2(max) equation for aerobically trained females.

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    Malek, Moh H; Housh, Terry J; Berger, Dale E; Coburn, Jared W; Beck, Travis W

    2004-10-01

    The purposes of the present study were to (a) modify previously published VO2(max) equations using the constant error (CE) values for aerobically trained females, (b) cross-validate the modified equations to determine their accuracy for estimating VO2(max) in aerobically trained females, (c) derive a new nonexercise-based equation for estimating VO2(max) in aerobically trained females if the modified equations are found to be inaccurate, and (d) cross-validate the new VO2(max) equation using the PRESS statistic and an independent sample of aerobically trained females. A total of 115 aerobically trained females (mean +/- SD: age = 38.5 +/- 9.4 yr) performed a maximal incremental test on a cycle ergometer to determine actual VO2(max). The predicted VO2(max) values from nine published equations were compared with actual VO2(max) by examining the CE, standard error of estimate (SEE), validity coefficient (r), and total error (TE). Cross-validation of the modified nonexercise-based equations on a random subsample of 50 subjects resulted in a %TE > or = 13% of the mean of actual VO2(max). Therefore, the following nonexercise-based VO2(max) equation was derived on a random subsample of 80 subjects: VO2(max) (mL x min(-1)) = 18.528 (weight in kg) + 11.993 (height in cm) - 17.197(age in yr) + 23.522 (h x wk(-1) of training) + 62.118 (intensity of training using the Borg 6-20) + 278.262 (natural log of years of training) - 1375.878 (R = 0.83, R2 adjusted = 0.67, and SEE = 259 mL x min(-1)). Cross-validation of this equation on the remaining sample of 35 subjects resulted in a %TE of 10%. The nonexercise equation presented here is recommended over previously published equations for estimating VO2(max) in aerobically trained females.

  16. Effects of training on muscle O2 transport at VO2max

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    Roca, J.; Agusti, A. G.; Alonso, A.; Poole, D. C.; Viegas, C.; Barbera, J. A.; Rodriguez-Roisin, R.; Ferrer, A.; Wagner, P. D.

    1992-01-01

    To quantify the relative contributions of convective and peripheral diffusive components of O2 transport to the increase in leg O2 uptake (VO2leg) at maximum O2 uptake (VO2max) after 9 wk of endurance training, 12 sedentary subjects (age 21.8 +/- 3.4 yr, VO2max 36.9 +/- 5.9 ml.min-1.kg-1) were studied. VO2max, leg blood flow (Qleg), and arterial and femoral venous PO2, and thus VO2leg, were measured while the subjects breathed room air, 15% O2, and 12% O2. The sequence of the three inspirates was balanced. After training, VO2max and VO2leg increased at each inspired O2 concentration [FIO2; mean over the 3 FIO2 values 25.2 +/- 17.8 and 36.5 +/- 33% (SD), respectively]. Before training, VO2leg and mean capillary PO2 were linearly related through the origin during hypoxia but not during room air breathing, suggesting that, at 21% O2, VO2max was not limited by O2 supply. After training, VO2leg and mean capillary PO2 at each FIO2 fell along a straight line with zero intercept, just as in athletes (Roca et al. J. Appl. Physiol. 67: 291-299, 1989). Calculated muscle O2 diffusing capacity (DO2) rose 34% while Qleg increased 19%. The relatively greater rise in DO2 increased the DO2/Qleg, which led to 9.9% greater O2 extraction. By numerical analysis, the increase in Qleg alone (constant DO2) would have raised VO2leg by 35 ml/min (mean), but that of DO2 (constant Qleg) would have increased VO2leg by 85 ml/min, more than twice as much. The sum of these individual effects (120 ml/min) was less (P = 0.013) than the observed rise of 164 ml/min (mean). This synergism (explained by the increase in DO2/Qleg) seems to be an important contribution to increases in VO2max with training.

  17. MAXIMAL OXIGEN UPTAKE (VO2 MAX AS THE INDICATOR OF PHYSICAL WORKING CAPACITY IN SPORTSMEN

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    Zvezdana Rajkovaca

    2005-12-01

    Full Text Available The term “aerobic capacity” represents the sum of aerobic metabolic processes in human organism. It is the basis of the physical working capacity. Value of the maximal oxygen uptake (VO2max is the best indicator for the aerobic capacity evaluation.The purpose of this study was to check the possibility of using VO2max as the indicator of aerobic capacity in sportsmen and to check differences in VO2max values in regard to non-sportsmen.The goals were: 1.Analyses of the VO2max values in sportsmen of various sports 2. Comparison of values of sportsmen with the values of non-sportsmen.This study included 67 sportsmen (rowers, football players and judoists and 28 nonsportsmen. VO2max was measured by using a direct method.The results obtained show statistically higher VO2max values in rowers (4,52 L/min - 55,8 mL/kg/min in regard to football players (4,2 L/min – 53,6 mL/kg/min, judoists (3,58 L/min - 47,2 mL/ kg/min and non-sportsmen (3,28 L/min – 42,3 mL/kg/min. Successful rowing requires high anaerobic capacity and, therefore, high VO2max.These results show higher values of VO2max in sportsmen in regard to non-sportsmen, which is the result of training only.

  18. Efek minuman kombinasi maltodekstrin dan vitamin C terhadap VO2maks atlet sepak bola

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    Desty Ervira Puspaningtyas

    2015-07-01

    Full Text Available Background: VO2max is one of win determiner in a game. Athletes receive training to improve technical skills, tactical skills, and physiology functions that can support the improvement of VO2max, so they can improve their achievement. Maltodextrin and vitamin C can be used as an ingredient for beverage products which can improve VO2max. Objective: To assess the effect of maltodextrin and vitamin C combination drink on VO2max in soccer athletes. Method: Type of this study was experimental design with the same subject design. The study was conducted from January 2014 until June 2014 at Culinary Laboratory Universitas Gadjah Mada (UGM and Stadium of Universitas Negeri Yogyakarta (UNY. Subjects of this study were 14 soccer players coming from Universitas Negeri Yogyakarta (UNY. Every subject had to fulfill the inclusion and exclusion criteria, and the subjects were chosen by purposive sampling. In the first treatment, subjects received the combination drink―a drink with a composition 15% of maltodextrin and 250 mg of vitamin C in 300 mL. After 6 days washout period, subjects received 300 mL plain water. Drinks were given 30 minutes before VO2max test. VO2max test method used in this study was yo-yo intermittent recovery test level 2 (IR-2. Results: VO2max when subjects consumed maltodextrin and vitamin C combination drink was significantly lower than VO2max when athletes consumed plain water (p=0,0000. Conclusion: Maltodextrin and vitamin C combination drink was less effective than plain water to enhance VO2max.

  19. Prior Knowledge of Trial Number Influences the Incidence of Plateau at VO2max.

    Science.gov (United States)

    Gordon, Dan; Caddy, Oliver; Merzbach, Viviane; Gernigon, Marie; Baker, James; Scruton, Adrian; Keiller, Don; Barnes, Richard

    2015-03-01

    The purpose of this study was to assess the VO2max plateau response at VO2max during a series of pre-determined trials. Ten male well-trained athletes (age, 23.0 ± 3.2; height, 183.3 ± 5.5 cm; mass 77.5 ± 11.1 Kg; VO2max 66.5 ± 5.0 ml(.)kg(-1,)min(-1)), but who were VO2max testing naïve and with prior-knowledge of trial number completed four incremental tests to volitional exhaustion, separated by ~72-h for the determination of VO2max and gas exchange threshold. Throughout all trials VO2max was recorded on a breath-by-breath basis using a pre-calibrated metabolic cart, using a plateau criterion of Δ VO2 ≤1.5 ml(.)kg(-1.)min(-1) over the final 2 consecutive 30 s sampling periods. A significant difference was observed between trial-1 and trial-4 for plateau incidence (p = 0.0285) rising from 20% in trial-1 to a 70% response rate in trial-4. Furthermore a significant difference was observed for VO2dif (difference between criterion value and Δ VO2) in trial-1, 1.02 ± 1.69 ml(.)kg(-1.)min(-1) (p = 0.038), with non-significant differences observed for all other trials, despite a non-significant difference for VO2max across all trials (p > 0.05). Finally, a significant difference was observed for effort perception (RPE) at volitional exhaustion between trial-1 (17.7 ± 1.3) and trial-4 (19.0 ± 1.4) (p = 0.0052). These data indicate that prior-knowledge of trial number can influence the manifestation of the VO2 plateau in a group of well-trained male athletes, thereby suggesting that a form of effort control is established in order to preserve the finite anaerobic capacity. Key pointsIn well-trained athletes the incidence of plateau at VO2max increases in conjunction with an increase in trial number and the associated sensations of pain and fatigue.By informing the participant of the number of trials to be completed a closed-loop condition is developed whereby effort in all trials is compared to a perceptually developed template.Closed-loop condition leads to a

  20. VO2max, ventilatory and anaerobic thresholds in rhythmic gymnasts and young female dancers.

    Science.gov (United States)

    Baldari, C; Guidetti, L

    2001-06-01

    This study examines the fitness level of a rhythmic gymnasts group and a young female classical dancers group. Aerobic power (VO2max), individual ventilatory (IVT) and anaerobic thresholds (IAT) were assessed in 12 elite rhythmic gymnasts, eight elite ballet dancers and 12 sedentary female subjects in the same age range (13-16 yrs). The VO2max, IVT and IAT were assessed during a continuous incremental running treadmill test. At IVT and IAT the VO2max expressed in ml x kg(-1) x min(-1) was significantly different between the three groups of subjects. The highest values were found in gymnasts (30.8+/-2.6 for IVT and 43.8+/-3.5 for IAT) followed by the values of dancers (21.7+/-2.8 for IVT and 30.5+/-3.1 for IAT) and controls (15.6+/-2.0 for IVT and 20.6+/-1.7 for IAT). When the VO2max was expressed in percent of VO2max, the values at IAT were significantly different between all groups (gymnasts: 84.9+/-0.7; dancers: 64.0+/-4.1; controls: 59.7+/-2.4) while at IVT no difference was found between dancers and controls (45.6+/-4.1 and 45.2+/-16, respectively). At maximal effort VO2 was significantly higher both in gymnasts and dancers (51.7+/-4.4 and 47.5+/-3.0 ml x kg(-1) x min(-1), respectively), than in controls (34.5+/-2.5 ml x kg(-1) x min(-1)). Although VO2max was similar between gymnasts and dancers, VO2 values at NT and IAT were able to discriminate the higher level of fitness in gymnasts with respect to dancers.

  1. Effect of exercise-induced arterial O2 desaturation on VO2max in women.

    Science.gov (United States)

    Harms, C A; McClaran, S R; Nickele, G A; Pegelow, D F; Nelson, W B; Dempsey, J A

    2000-06-01

    We have recently reported that many healthy habitually active women experience exercise induced arterial hypoxemia (EIAH). We questioned whether EIAH affected VO2max in this population and whether the effect was similar to that reported in men. Twenty-five healthy young women with widely varying fitness levels (VO2max, 56.7 +/- 1.5 mL x kg(-1) x min(-1); range: 41-70 mL x kg(-1) x min(-1)) and normal resting lung function performed two randomized incremental treadmill tests to VO2max (FIO2: 0.21 or 0.26) during the follicular phase of their menstrual cycle. Arterial blood samples were taken at rest and near the end of each workload during the normoxic test. During room air breathing at VO2max, SaO2 decreased to 91.8 +/- 0.4% (range 87-95%). With 0.26 FIO2, SaO2, at VO2max remained near resting levels and averaged 96.8 +/- 0.1% (range 96-98%). When arterial O2 desaturation was prevented via increased FIO2, VO2max increased in 22 of the 25 subjects and in proportion to the degree of arterial O2 desaturation experienced in normoxia (r = 0.88). The improvement in VO2max when systemic normoxia was maintained averaged 6.3 +/- 0.3% (range 0 to +15%) and the slope of the relationship was approximately 2% increase in VO2max for every 1% decrement in the arterial oxygen saturation below resting values. About 75% of the increase in VO2max resulted from an increase in VO2 at a fixed maximal work rate and exercise duration, and the remainder resulted from an increase in maximal work rate. These data demonstrate that even small amounts of EIAH (i.e., >3% delta SaO2 below rest) have a significant detrimental effect on VO2max in habitually active women with a wide range of VO2max. In combination with our previous findings documenting EIAH in females, we propose that inadequate pulmonary structure/function in many habitually active women serves as a primary limiting factor in maximal O2 transport and utilization during maximal exercise.

  2. Achievement of VO2max criteria during a continuous graded exercise test and a verification stage performed by college athletes.

    Science.gov (United States)

    Mier, Constance M; Alexander, Ryan P; Mageean, Amanda L

    2012-10-01

    The purpose of this study was to determine the incidence of meeting specific VO2max criteria and to test the effectiveness of a VO2max verification stage in college athletes. Thirty-five subjects completed a continuous graded exercise test (GXT) to volitional exhaustion. The frequency of achieving various respiratory exchange ratio (RER) and age-predicted maximum heart rate (HRmax) criteria and a VO2 plateau within 2 and 2.2 ml·kg(-1)·min(-1) (VO2max plateau was 5 (≤2 ml·kg(-1)·min(-1)) and 7 (≤2.2 ml·kg(-1)·min(-1)), RER criteria 34 (≥1.05), 32 (≥1.10), and 24 (≥1.15), HRmax criteria, 35 (VO2max and HRmax did not differ between GXT and the verification stage (53.6 ± 5.6 vs. 55.5 ± 5.6 ml·kg(-1)·min(-1) and 187 ± 7 vs. 187 ± 6 b·min(-1)); however, the RER was lower during the verification stage (1.15 ± 0.06 vs. 1.07 ± 0.07, p = 0.004). Six subjects achieved a similar VO2 (within 2.2 ml·kg(-1)·min(-1)), whereas 4 achieved a higher VO2 compared with the GXT. These data demonstrate that a continuous GXT limits the college athlete's ability to achieve VO2max plateau and certain RER and HR criteria. The use of a verification stage increases the frequency of VO2max achievement and may be an effective method to improve the accuracy of VO2max measurements in college athletes.

  3. Cardiovascular drift and Vo2max during cycling and walking in a temperate environment.

    Science.gov (United States)

    Wingo, Jonathan E; Salaga, Laura J; Newlin, Mia K; Cureton, Kirk J

    2012-07-01

    Different muscle recruitment patterns during cycling and walking may influence the magnitude of cardiovascular drift (CV drift) during these respective modes of exercise, but whether this also influences the magnitude of reduced maximal oxygen uptake (Vo2max) associated with CV drift is unknown.This study tested the hypothesis that cycling results in greater CV drift and a greater decrement in Vo2max than walking in a temperate environment. CV drift was measured in nine recreationally active women (ages = 23 +/- 2 yr, Vo2max = 43.0 +/- 5.5 ml x kg(-1) x min(-1)) between 15 and 45 min of cycling or walking at 60% Vo2max on Separate occasions in 22 degrees C, 44% relative humidity. A graded exercise test to measure Vo2max was performed immediately after the submaximal exercise bout with no cessation of exercise. During separate trials involving each exercise mode, Vo2max was measured after 15 min of submaximal exercise so that changes in Vo2max between 15 and 45 min of exercise could be assessed between the same points in time in which CV drift occurred. Across both conditions, heart rate (HR) increased 5.4% and stroke volume (SV) decreased 11% from 15 to 45 min, but Vo2max was not significantly affected (7% reduction; 2.70 +/- 0.5 L min(-1) vs. 2.52 +/- 0.6 L min(-1)). In a temperate environment, a small CV drift corresponds to a small, non-significant decrease in Vo2max, regardless of whether the exercise performed is cycling or walking.

  4. New Methods for Processing and Quantifying VO2 Kinetics to Steady State: VO2 Onset Kinetics

    Science.gov (United States)

    McNulty, Craig R.; Robergs, Robert A.

    2017-01-01

    Current methods of oxygen uptake (VO2) kinetics data handling may be too simplistic for the complex physiology involved in the underlying physiological processes. Therefore, the aim of this study was to quantify the VO2 kinetics to steady state across the full range of sub-ventilatory threshold work rates, with a particular focus on the VO2 onset kinetics. Ten healthy, moderately trained males participated in five bouts of cycling. Each bout involved 10 min at a percentage of the subject's ventilation threshold (30, 45, 60, 75, 90%) from unloaded cycling. The VO2 kinetics was quantified using the conventional mono-exponential time constant (tau, τ), as well as the new methods for VO2 onset kinetics. Compared to linear modeling, non-linear modeling caused a deterioration of goodness of fit (main effect, p kinetics were also improved using a modified application of the mono-exponential model (main effect, p kinetics data is similar across all subjects and absolute exercise intensities, and thereby independent of subject fitness and τ. This could indicate that there are no functional limitations between subjects during this onset phase, with limitations occurring for the latter transition to steady state. Finally, the continuing use of mono-exponential modeling could mask important underlying physiology of more instantaneous VO2 responses to steady state. Consequently, further research should be conducted on this new approach to VO2 onset kinetics. PMID:29018361

  5. The efficacy of a self-paced VO2max test during motorized treadmill exercise.

    Science.gov (United States)

    Faulkner, James; Mauger, Alexis R; Woolley, Brandon; Lambrick, Danielle

    2015-01-01

    To assess the utility of a self-paced maximal oxygen uptake (VO2max) test (SPV) in eliciting an accurate measure of VO2max in comparison with a traditional graded exercise test (GXT) during motorized treadmill exercise. This was a cross-sectional experimental study whereby recreationally trained men (n = 13, 25.5 ± 4.6 y) completed 2 maximal exercise tests (SPV, GXT) separated by a 72-h recovery period. The GXT was continuous and incremental, with prescribed 1-km/h increases every 2 min until the attainment of VO2max. The SPV consisted of 5 × 2-min stages of incremental exercise, which were self-selected and adjusted according to 5 prescribed RPE levels (RPE 11, 13, 15, 17, and 20). Although no significant differences in VO2max were observed between the SPV and GXT (63.9 ± 3.3 cf 60.9 ± 4.6 mL · kg-1 · min-1, respectively, P > .05), the apparent 4.7% mean difference may be practically important. The 95% limits-of-agreement analysis was 3.03 ± 11.49 mL · kg-1 · min-1. Therefore, in the worst-case scenario, the GXT may underestimate measured VO2max as ascertained by the SPV by up to 19%. Conversely, the SPV could underestimate the GXT by 14%. The current study has shown that the SPV is an accurate measure of VO2max during exercise on a motorized treadmill and may provide a slightly higher VO2max value than that obtained from a traditional GXT. The higher VO2max during the SPV may be important when prescribing training or monitoring athlete progression.

  6. Ultrafast structural dynamics of VO2

    Science.gov (United States)

    Lysenko, Sergiy; Kumar, Nardeep; Rúa, Armando; Figueroa, José; Lu, Junqiang; Fernández, Félix

    2017-08-01

    Distinct contribution of acoustic and optical phonons in light-induced lattice transformation was resolved at different time scales by monitoring the insulator-to-metal phase transition in epitaxial and nonepitaxial VO2 films. Applying the ultrafast angle-resolved light scattering technique we demonstrate a significant influence of internal misfit strain in epitaxial films on subpicosecond phase transition dynamics. This technique also allows for observing a contribution of structural defects in the evolution of the transient state. The ultrafast structural phase transition dynamics is discussed in terms of the Ginzburg-Landau formalism. Using a set of experimental data we reconstruct the thermodynamic potential of photoexcited VO2 and provide a phenomenological model of the ultrafast light-induced structural phase transition.

  7. Effects of erythrocyte infusion on VO2max at high altitude

    DEFF Research Database (Denmark)

    Young, Jette Feveile; Sawka, M N; Muza, S R

    1996-01-01

    This study investigated whether autologous erythrocyte infusion would ameliorate the decrement in maximal O2 uptake (VO2max) experienced by lowlanders when they ascend to high altitude. VO2max was measured in 16 men (treadmill running) at sea level (SL) and on the 1st (HA1) and 9th (HA9) days...... of high-altitude (4,300 m) residence. After VO2max was measured at SL, subjects were divided into two matched groups (n = 8). Twenty-four hours before ascent to high altitude, the experimental group received a 700-ml infusion of autologous erythrocytes and saline (42% hematocrit), whereas the control...... group received only saline. The VO2max of erythrocyte-infused [54 +/- 1 (SE) ml.kg-1.min-1] and control subjects (52 +/- 2 ml.kg-1.min-1) did not differ at SL before infusion. The decrement in VO2max on HA1 did not differ between groups, averaging 26% overall, despite higher (P

  8. Crossvalidation of two heart rate-based equations for predicting VO2max in white and black men.

    Science.gov (United States)

    Esco, Michael R; Olson, Michele S; Williford, Henry N; Mugu, Emmanuel M; Bloomquist, Barbara E; McHugh, Aindrea N

    2012-07-01

    The purpose of this investigation was to crossvalidate 2 equations that use the ratio of maximal heart rate (HRmax) to resting HR (HRrest) for predicting maximal oxygen consumption (VO2max) in white and black men. One hundred and nine white (n = 51) and black (n = 58) men completed a maximal exercise test on a treadmill to determine VO2max. The HRrest and HRmax were used to predict VO2max via the HRindex and HRratio equations. Validity statistics were done to compare the criterion versus predicted VO2max values across the entire cohort and within each race separately. For the entire group, VO2max was significantly overestimated with the HRindex equation, but the HRratio equation yielded no significant difference compared with the criterion. In addition, there were no significant differences shown between VO2max and either HR-based prediction equation for the white subgroup. However, both equations significantly overestimated VO2max in the black group. Furthermore, large standard error of estimates (ranging from 6.92 to 7.90 ml·kg(-1)·min(-1)), total errors (ranging from 8.30 to 8.62 ml·kg(-1)·min(-1)), and limits of agreement (ranging from upper limits of 16.65 to lower limits of -18.25 ml·kg(-1)·min(-1)) were revealed when comparing the predicted to criterion VO2max for both the groups. Considering the results of this investigation, the HRratio and HRindex methods appear to crossvalidate and prove useful for estimating the mean VO2max in white men as a group but not for an age-matched group of black men. However, because of inflated values for error, caution should be exercised when using these methods to predict individual VO2max.

  9. Metamaterials based on the phase transition of VO2

    Science.gov (United States)

    Liu, Hongwei; Lu, Junpeng; Renshaw Wang, Xiao

    2018-01-01

    In this article, we present a comprehensive review on recent research progress in design and fabrication of active tunable metamaterials and devices based on phase transition of VO2. Firstly, we introduce mechanisms of the metal-to-insulator phase transition (MIPT) in VO2 investigated by ultrafast THz spectroscopies. By analyzing the THz spectra, the evolutions of MIPT in VO2 induced by different external excitations are described. The superiorities of using VO2 as building blocks to construct highly tunable metamaterials are discussed. Subsequently, the recently demonstrated metamaterial devices based on VO2 are reviewed. These metamaterials devices are summarized and described in the categories of working frequency. In each working frequency range, representative metamaterials based on VO2 with different architectures and functionalities are reviewed and the contributions of the MIPT of VO2 are emphasized. Finally, we conclude the recent reports and provide a prospect on the strategies of developing future tunable metamaterials based on VO2.

  10. Effect of the VO2 time-averaging interval on the reproducibility of VO2max in healthy athletic subjects.

    Science.gov (United States)

    Midgley, Adrian W; McNaughton, Lars R; Carroll, Sean

    2007-03-01

    Limited research has investigated the most appropriate oxygen uptake (VO2) data averaging method to obtain reliable and valid maximal oxygen uptake (VO2max) values. This study investigated the effect of the VO2 time-averaging interval on the reproducibility of VO2max. Twenty-two competitive distance runners (six female) performed two identical incremental treadmill tests to their limit of exercise tolerance separated by at least 48 h. Commencing at 7 km h(-1), running speed was increased by 1 km h(-1) per minute for five stages and 0.5 km h(-1) thereafter. Breath-by-breath VO2 data collected during each incremental test were time-averaged over 10-, 15-, 20-, 30- and 60-s and the highest averaged VO2 value was regarded as VO2max for each time-averaging interval. The VO2max values derived from different VO2 time-averaging intervals were significantly different for the first (F = 39.6; PVO2max to significantly increase as the time-averaging interval became shorter. The reproducibility of VO2max was similar for all five VO2 time-averages, with no significant differences between the within-subject variance (F = 0.4; P = 0.6). The results of this study suggests that the reproducibility of VO2max is not affected by the length of the VO2 time-average interval. However, VO2max was significantly altered by changing the VO2 time-averaging interval between 10 and 60 s. Consistency in the VO2 time-averaging interval is therefore an important methodological consideration for repeated determinations of VO2max.

  11. Crossvalidation of two 20-m shuttle-run tests for predicting VO2max in female collegiate soccer players.

    Science.gov (United States)

    Green, Michael S; Esco, Michael R; Martin, Tyler D; Pritchett, Robert C; McHugh, Aindrea N; Williford, Henry N

    2013-06-01

    The aim of this study was twofold: (a) to compare the maximal attained speed (MAS) from the 20-m shuttle (MST) and 20-m square-shuttle (SST) tests and (b) to crossvalidate 2 equations for predicting maximal oxygen consumption (VO2max) that were previously developed from MST and SST in a group of female collegiate soccer players. Thirty-nine subjects (age: 20.1 ± 1.5 years) participated in the study. A maximal graded exercise treadmill test was used to measure VO2max. In addition, VO2max was predicted from the MAS obtained during MST ((pred)VO2maxMST) and SST ((pred)VO2maxSST) using previously developed equations. Measured VO2max for the group was 44.2 ± 3.3 ml·kg(-1)·min(-1). The MAS was 12.5 ± 0.6 km·h(-1) for MST and 13.3 ± 0.8 km·h(-1) for SST (p VO2max (p VO2max than MST in the group of athletes.

  12. High Resolution MEMS Accelerometers to Estimate VO2 and Compare Running Mechanics between Highly Trained Inter-Collegiate and Untrained Runners

    OpenAIRE

    McGregor, Stephen J.; Busa, Michael A.; Yaggie, James A; Bollt, Erik M.

    2009-01-01

    Background The purposes of this study were to determine the validity and reliability of high resolution accelerometers (HRA) relative to VO2 and speed, and compare putative differences in HRA signal between trained (T) and untrained (UT) runners during treadmill locomotion. Methodology Runners performed 2 incremental VO2max trials while wearing HRA. RMS of high frequency signal from three axes (VT, ML, AP) and the Euclidean resultant (RES) were compared to VO2 to determine validity and reliab...

  13. Variação diurna e resposta da cinética do VO2 de ciclistas durante exercício muito intenso Diurnal variation and Vo2 kinetic response of cyclists during heavy exercis e

    Directory of Open Access Journals (Sweden)

    Marcos G. Santana

    2008-06-01

    Full Text Available O objetivo do presente estudo foi avaliar a influência da hora do dia nos parâmetros da cinética do consumo de oxigênio de ciclistas durante exercício muito intenso. Nove voluntários do sexo masculino realizaram exercícios de carga constante às 08:00, 13:00 e 18:00 h, em dias diferentes. Estes exercícios foram realizados duas vezes em cada visita, com um intervalo de 1 h entre eles. A intensidade usada foi de 75%Δ (75% da diferença entre o VO2 no limiar de lactato e o VO2max. A amplitude do componente primário do VO2 (2597 ± 273 ml.min-1, 2513 ± 268 ml.min-1 e 2609 ± 370 ml.min-1, a constante de tempo do componente primário do VO2 (19.3 ± 2.5 s, 18.4 ± 3.0 s e 19.7 ± 3.9 s, o componente lento do VO2 (735 ± 81 ml.min-1, 764 ± 99 ml.min-1 e 680 ± 121 ml.min-1 e o tempo de resposta média (51.8 ± 4.2 s, 51.2 ± 4.2 s e 51.4 ± 3.4 s não apresentaram diferenças significativas entre os diferentes horários do dia (08:00, 13:00 e 18:00 h, assim como os demais parâmetros da cinética do VO2. Estes resultados sugerem que a resposta da cinética do VO2 de ciclistas durante exercício muito intenso (75%Δ não é influenciada pela hora do dia.The objective of the present study was to evaluate the influence of the time of day on the parameters of oxygen uptake kinetics of trained cyclists during high intensity exercise. Nine male volunteers repeated bouts at constant loads at 08:00, 13:00 and 18:00 h on different days. These exercise bouts were performed twice on each occasion, with an interval of 1 h between them. The load intensity used was 75%Δ (75% of the difference between the VO2 at the lactate threshold and the VO2max. The primary VO2 amplitude (2597 ± 273 ml.min-1, 2513 ± 268 ml.min-1 and 2609 ± 370 ml.min-1, the primary VO2 time constant (19.3 ± 2.5 s, 18.4 ± 3.0 s and 19.7 ± 3.9 s, the VO2 slow component (735 ± 81 ml.min-1, 764 ± 99 ml.min-1 and 680 ± 121 ml.min-1 and the mean response time (51.8 ± 4.2 s, 51

  14. Echinacea purpurea supplementation does not enhance VO2max in distance runners.

    Science.gov (United States)

    Baumann, Cory W; Bond, Kelsey L; Rupp, Jeffrey C; Ingalls, Christopher P; Doyle, J Andrew

    2014-05-01

    Oral supplementation of Echinacea purpurea (ECH) has been reported to increase levels of serum erythropoietin and as a result improve endurance performance in untrained subjects. The purpose of this study was to determine if ECH supplementation alters maximal oxygen uptake (VO2max) in trained endurance runners. Using a double-blind design, 16 trained endurance runners (9 ECH and 7 placebo [PLA]) supplemented with either 8,000 mg·d(-1) of ECH or wheat flour (PLA) for 6 weeks. Maximal aerobic treadmill tests and blood samples were measured before and after supplementation to determine VO2max, hematocrit (Hct), and hemoglobin (Hb). VO2max, Hct, and Hb did not differ between the ECH and PLA groups before or after supplementation. Furthermore, supplementation of ECH failed to improve VO2max (67.37 ± 4.62 vs. 67.23 ± 5.82 ml·kg(-1)·min(-1)), Hct (43.57 ± 2.38 vs. 42.85 ± 1.46%), or Hb (14.93 ± 1.27 vs. 15.55 ± 0.80 g·dL(-1)) from baseline measurements. Echinacea purpurea supplementation of 8,000 mg·d(-1) for 6 weeks failed to increase VO2max, Hct, or Hb in trained endurance runners and thus does not seem to influence physiological variables that affect distance running performance.

  15. Non-exercise estimation of VO2max using the International Physical Activity Questionnaire

    Science.gov (United States)

    Schembre, Susan M.; Riebe, Deborah A.

    2011-01-01

    Non-exercise equations developed from self-reported physical activity can estimate maximal oxygen uptake (VO2max) as well as submaximal exercise testing. The International Physical Activity Questionnaire (IPAQ) is the most widely used and validated self-report measure of physical activity. This study aimed to develop and test a VO2max estimation equation derived from the IPAQ-Short Form (IPAQ-S). College-aged males and females (n = 80) completed the IPAQ-S and performed a maximal exercise test. The estimation equation was created with multivariate regression in a gender-balanced subsample of participants, equally representing five levels of fitness (n = 50) and validated in the remaining participants (n = 30). The resulting equation explained 43% of the variance in measured VO2max (SEE = 5.45 ml·kg-1·min-1). Estimated VO2max for 87% of individuals fell within acceptable limits of error observed with submaximal exercise testing (20% error). The IPAQ-S can be used to successfully estimate VO2max as well as submaximal exercise tests. Development of other population-specific estimation equations is warranted. PMID:21927551

  16. Influence of blood donation on the incidence of plateau at VO2max.

    Science.gov (United States)

    Gordon, Dan; Wood, Madeleine; Porter, Andrew; Vetrivel, Vignesh; Gernigon, Marie; Caddy, Oliver; Merzbach, Viviane; Keiller, Don; Baker, James; Barnes, Richard

    2014-01-01

    The purpose of this study was to examine the effects of reductions in blood volume and associated oxygen-carrying capacity on the incidence of plateau at VO2max. Fifteen well-trained athletes (age 23.3 ± 4.5; mass 77.4 ± 13.1 kg, height 180.1 ± 6.0 cm) completed three incremental cycle tests to volitional exhaustion, of which the first was defined as familiarisation, with the remaining two trials forming the experimental conditions of pre- (UBL) and post-(BLE) blood donation (~ 450 cm(3)). The work rate for the incremental tests commenced at 100 W for 60 s followed by a ramp of 0.42 W s(-1), with cadence being held constant at 80 rpm. Throughout all trials, VO2 was determined on a breath-by-breath basis using a pre-calibrated metabolic cart. The criteria for plateau determination was a ∆VO2 ≤ 50 ml min(-1) over the final two consecutive 30 s sampling periods. Despite a significant (P = 0.0028) 9.4 % reduction in haemoglobin concentration and 10.8 % (P = 0.016) reduction in erythrocyte count between UBL and BLE, there was no change in plateau incidence. However, significant differences were observed for both VO2max (P = 0.0059) 51.3 ± 7.6 (UBL) 48.4 ± 7.9 ml kg(-1) min(-1) (BLE) and gas exchange threshold arrival time 383.4 ± 85.2 s (UBL) 349.2 ± 71.4 s (BLE) (P = 0.0028). These data suggest that plateau at VO2max is unaffected by O2 availability lending support to the notion of the plateau being dependent on the anaerobic capacity and the classically orientated concept of VO2max.

  17. A maximal multistage 20-m shuttle run test to predict VO2 max.

    Science.gov (United States)

    Léger, L A; Lambert, J

    1982-01-01

    In order to validate a maximal multistage 20-m shuttle run test for the prediction of VO2 max, 91 adults (32 females and 59 males, aged 27.3 +/- 9.2 and 24.8 +/- 5.5 year respectively and with mean VO2 max (+/- SD) of 39.3 +/- 8.3 and 51.6 +/- 7.8 ml . kg-1 . min-1 respectively) performed the test and had VO2 max estimated by the retroextrapolation method (extrapolation to time zero of recovery of the exponential least squares regression of the first four 20-s recovery VO2 values). Starting at 8 km . h-1 and increasing by 0.5 km . h-1 every 2 min, the 20-m shuttle run test enabled prediction of the VO2 max (y, ml . kg-1 . min-1) from the maximal speed (x, km . h-1) by means of the following regression equation: y = 5.857x - 19.458; r = 0.84 and SEE = 5.4. Later, the multistage protocol was slightly modified to its final version, in which the test started at stage 7 Met and continued with a 1 Met (3.5 ml O2 . kg-1 . min-1) increment every 2 min. Twenty-five of the 91 subjects performed the 20-m shuttle test twice, once on a hard, low-friction surface (vinyl-asbestos tiles) and another time on a rubber floor, as well as a walking maximal multistage test on an inclined treadmill. There was no difference between the means of these tests or between the slopes of the VO2max - maximal speed regressions for the two types of surfaces. The 20-m shuttle run test and another maximal multistage field test involving continuous track running gave comparable results (r = 0.92, SEE = 2.6 ml O2 . kg-1 . min-1, n = 70). Finally, test and retest of the 20-m shuttle run test also yielded comparable results (r = 0.975, SEE = 2.0 ml O2 . kg-1 . min-1, n = 50). It is concluded that the 20-m shuttle run test is valid and reliable test for the prediction of the VO2 max of male and female adults, individually or in groups, on most gymnasium surfaces.

  18. VO2max and ventilatory threshold of trained cyclists are not affected by 28-day L-arginine supplementation.

    Science.gov (United States)

    Sunderland, Kyle L; Greer, Felicia; Morales, Jacobo

    2011-03-01

    The ergogenic effect of L-arginine on an endurance-trained population is not well studied. The few studies that have investigated L-arginine on this population have not been conducted in a laboratory setting or measured aerobic variables. The purpose of the current study is to determine if 28 days of L-arginine supplementation in trained male cyclists affects VO2max and ventilatory threshold (VT). Eighteen (18) endurance-trained male cyclists (mean ± SD, age: 36.3 ± 7.9 years; height: 182.4 ± 4.6 cm; and body mass: 79.5 ± 4.7 kg) performed a graded exercise test (GXT; 50 W + 25 W·min) before and after 28 days of supplementation with L-arginine (ARG; 2 × 6 g·d) or placebo (PLA; cornstarch). The GXT was conducted on the subject's own bicycle using the RacerMate CompuTrainer (Seattle, WA, USA). VO2 was continuously recorded using the ParvoMedics TrueOne 2400 metabolic cart (Salt Lake City, UT, USA) and VT was established by plotting the ventilatory equivalent for O2 (VE/VO2) and the ventilatory equivalent for CO2 (VE/VCO2) and identifying the point at which VE/VO2 increases with no substantial changes in VE/VCO2. L-arginine supplementation had no effect from initial VO2max (PL, 58.7 ± 7.1 ml·kg·min; ARG, 63.5 ± 7.3 ml·kg·min) to postsupplement VO2max (PL, 58.9 ± 6.0 ml·kg·min; ARG, 63.2 ± 7.2 ml·kg·min). Also, no effect was seen from initial VT (PL, 75.7 ± 4.6% VO2max; ARG, 76.0 ± 5.3% VO2max) to postsupplement VT (PL, 74.3 ± 8.1% VO2max; ARG, 74.2 ± 6.4% VO2max). These results indicate that L-arginine does not impact VO2max or VT in trained male cyclists.

  19. Antepartum cardiorespiratory fitness (CRF) quantification by estimation of maximal oxygen consumption (Vo2 max) in pregnant South Indian women.

    Science.gov (United States)

    Chakaravertty, Biswajit; Parkavi, K; Coumary, Sendhil A; Felix, A J W

    2012-04-01

    The aim of the study was to calculate the maximal oxygen consumption (Vo2max) for pregnant women of varying trimesters and to quantify the cardiorespiratory fitness (CRF)with the objective of being able to determine the exercise dose for antenatal women which can be prescribed to achieve optimal exercise benefits during various trimesters. A study group comprising 64 pregnant women with uncomplicated singleton pregnancy and control group with 77 non-pregnant women were subjected to Cooper's 12 minutes walk test. From the distance covered in 12 minutes, Vo2max was calculated. The Vo2max values were statistically analysed between the non-pregnant and pregnant and also its variability among the trimesters. Percentile tables of Vo2max were drawn and multiple comparisons were applied. Results show that the Vo2max values among non-pregnant and first trimester ranges between 18 and 22 ml/kg/minute. Trimesters II and III had a range of Vo2max values between 16-20 and 14-18 ml/kg/minute respectively. The CRF of pregnant women significantly reduced to 6%, 9% and 18% in each trimester respectively when compared with the reference table framed out of non-pregnant Vo2max values. Among the study group the reduction in Vo2max values had no statistical significance between first 2 trimesters but trimester III significantly differs from other trimesters. The exercise prescription cannot be the same for pregnant and non-pregnant women. Even among the pregnant women, III trimester needs separate exercise prescription from the other two trimesters as CRF is markedly compromised towards term.

  20. Luminous transmittance and phase transition temperature of VO 2 ...

    African Journals Online (AJOL)

    The phase transition temperature (τc) of the films was obtained from both the transmittance and sheet resistance against temperature curves. A change in sheet resistance of 2 to 3 orders of magnitude was observed for both undoped and Ce-doped VO2 films. Comparison between undoped and doped VO2 films revealed ...

  1. Influence of work-interval intensity and duration on time spent at a high percentage of VO2max during intermittent supramaximal exercise.

    Science.gov (United States)

    Wakefield, Benjamin R; Glaister, Mark

    2009-12-01

    The purpose of this study was to examine the effect of work-interval duration (WID) and intensity on the time spent at, or above, 95% VO2max (T95 VO2max) during intermittent bouts of supramaximal exercise. Over a 5-week period, 7 physically active men with a mean (+/-SD) age, height, body mass, and VO2max of 22 +/- 5 years, 181.5 +/- 5.6 cm, 86.4 +/- 11.4 kg, and 51.5 +/- 1.5 ml.kg-1.min-1, respectively, attended 7 testing sessions. After completing a submaximal incremental test on a treadmill to identify individual oxygen uptake/running velocity relationships, subjects completed a maximal incremental test to exhaustion to VO2max and subsequently (from the aforementioned relationship) the minimum velocity required to elicit VO2max (vVO2max). In a random order, subjects then carried out 3 intermittent runs to exhaustion at both 105% and 115% vVO2max. Each test used a different WID (20 s, 25 s, or 30 s) interspersed with 20-second passive recovery periods. Results revealed no significant difference in T95 vVO2max for intermittent runs at 105% versus 115% vVO2max (p = 0.142). There was, however, a significant effect (p VO2max, with WIDs of 30 seconds enabling more time relative to WIDs of 20 seconds (p = 0.018) and 25 seconds (p = 0.009). Moreover, there was an interaction between intensity and duration such that the effect of WID was magnified at the lower exercise intensity (p = 0.046). In conclusion, despite a number of limitations, the results of this investigation suggest that exercise intensities of approximately 105% vVO2max combined with WIDs greater than 25 seconds provide the best way of optimizing T95 VO2max when using fixed 20-second stationary rest periods.

  2. Improving the electrocatalytic performance of carbon nanotubes for VO2+/VO2+ redox reaction by KOH activation

    Science.gov (United States)

    Dai, Lei; Jiang, Yingqiao; Meng, Wei; Zhou, Huizhu; Wang, Ling; He, Zhangxing

    2017-04-01

    In this paper, carbon nanotubes (CNTs) was activated by KOH treatment at high temperature and investigated as catalyst for VO2+/VO2+ redox reaction for vanadium redox flow battery (VRFB). X-ray photoelectron spectroscopy results suggest that the oxygen-containing groups can be introduced on CNTs by KOH activation. The mass transfer of vanadium ions can be accelerated by chemical etching by KOH activation and improved wettability due to the introduction of hydrophilic groups. The electrochemical properties of VO2+/VO2+ redox reaction can be enhanced by introduced oxygen-containing groups as active sites. The sample treated at 900 °C with KOH/CNTs mass ratio of 3:1 (CNTs-3) exhibits the highest electrocatalytic activity for VO2+/VO2+ redox reaction. The cell using CNTs-3 as positive catalyst demonstrates the smallest electrochemical polarization, the highest capacity and efficiency among the samples. Using KOH-activated CNTs-3 can increase the average energy efficiency of the cell by 4.4%. This work suggests that KOH-activated CNTs is a low-cost, efficient and promising catalyst for VO2+/VO2+ redox reaction for VRFB system.

  3. THE RELATIONSHIP BETWEEN AEROBIC POWER AND REPEATED SPRINT ABILITY IN YOUNG SOCCER PLAYERS WITH DIFFERENT LEVELS OF VO2 MAX

    Directory of Open Access Journals (Sweden)

    Rostam Alizadeh

    2010-06-01

    Full Text Available In some team sports such as soccer which is interval, athletes need to prepare themselves immediatelyfor the next activity. Therefore it is very important to have enough information on characteristics of recovery phase and quick recovery to the first situation and to have the minimum speed reduction. The purpose of this study was to determine the relationship between aerobic power and repeated sprint ability (RSA or decrementindex in young soccer players in three different levels of Vo2max. Methods: For this reason 41 volunteers were divided in to three groups with different levels of Vo2max ml.kg-1.min-1 low 37.22 ± 2.3 (n= 18, age 17.1 ± 0.9 year, height 170.6 ± 0.76 cm, weight 67.1 ± 5.05 kg medium 46.46± 1.97 ml.kg-1.min-1 (n= 13, age 17.6± 0.76year, height 173.8 ± 4.84 cm, weight 65.9 ± 4.92 kg and high 55.63 ± 1.52 ml.kg-1.min-1 (n=10, age 17.4 ±0.69 year, height 177 ± 3.23 cm, weight 71.4 ± 3.94 kg. To determine Vo2max a graded exercise test until volitional exhaustion on treadmill was used, and also RAST was used to measure RSA. The lactate accumulation was measured before and after RSA protocol. Pearson's correlation was used to determine the correlation between the aerobic power and RSA. The results indicated that there are significant relationship between Vo2max anddecremental index in low Vo2max group (r= 0.86, p= 0.001, no significant relationship medium Vo2max group (r= 0.14, p= 0.63 and negative significant relationship in high Vo2max group (r= - 0.64, p= 0.04. There are no significant relationship between Lactate accumulation and decremental index in medium (r= 0.005, p= 0.98 and high Vo2max groups (r=0.27, p= 0.45. Discussion: It is possible that the recovery of inter muscular resources relates to aerobic ability, but there are other factors effective in RSA rather than Vo2max and Lactate accumulation. The current study showed a normal curved relationship between Vo2max and RSA.

  4. Predicting VO2max with an objectively measured physical activity in Japanese women.

    Science.gov (United States)

    Cao, Zhen-Bo; Miyatake, Nobuyuki; Higuchi, Mitsuru; Miyachi, Motohiko; Ishikawa-Takata, Kazuko; Tabata, Izumi

    2010-01-01

    To investigate the use of the accelerometer-determined physical activity (PA) intensity variables as the objective PA variables for estimating VO2max in Japanese adult women. The subjects of this study were 148 Japanese women aged 20 to 69 yr. Maximal oxygen uptake (VO2max) was measured with a maximal incremental test on a bicycle ergometer. Daily step counts (SC) and the amount spent in moderate to vigorous PA (MVPA) and vigorous PA (VPA) were measured using accelerometer-based activity monitors for 7 consecutive days. Using data of age, SC, MVPA, or VPA, and either body mass index (BMI) or waist circumference (WC), the nonexercise VO2max prediction models were derived as BMI models(MVPA), WC models(MVPA), BMI models(VPA), and WC models(VPA), and cross-validated by using two separate cross-validation procedures. SC, MVPA, and VPA were significantly related to VO2max (r = 0.43, r = 0.52, and r = 0.58, respectively). The multiple correlation coefficients for the BMI and WC models(MVAP) were 0.83 and 0.85, respectively, and for the BMI and WC models(VPA), they were 0.85 and 0.86, respectively. The SEE was 3.3 and 3.1 mL x kg(-1) x min(-1) for the BMI and WC models(MVPA), respectively, and it was 3.1 and 3.0 mL x kg(-1) x min(-1) for the BMI and WC models(VPA), respectively. All regression models demonstrated a high level of cross-validity supported by the minor shrinkage of the coefficient of determination and the increment of SEE in the predicted residual sum of squares procedure, and by small constant errors for the subgroups of age, SC, and VO2max between 25 and 35 mL x kg(-1) x min(-1). This study demonstrated that multiple regression models using data of MVPA or VPA were useful in predicting VO2max for Japanese adult women.

  5. The aerobic fitness (VO2 peak) and alpha-fibrinogen genetic polymorphism in obese and non-obese Chinese boys.

    Science.gov (United States)

    He, Z-H; Ma, L-H

    2005-05-01

    The purpose of the study was to compare the aerobic fitness (VO (2) peak) between obese and non-obese boys at pre-puberty and examine the effect of body composition on VO (2) peak in this cohort with reference to TaqI polymorphism at alpha-fibrinogen gene locus. Seventy-seven Chinese boys with similar lifestyle participated in the study. Among them, 47 were diagnosed as obese. VO (2) peak was measured by a treadmill test and body composition was assessed via a combined anthropometrical and bioelectrical impedance analysis method. The alpha-fibrinogen genetic polymorphism was detected through PCR-based digestion with TaqI restriction enzyme. The results indicated that VO (2) peak was significantly lower in obese boys compared with normal weight counterparts when the data were expressed either in conventional ratio unit (ml (-1) . min (-1) . lean body weight [LBW] (-1)) or in allometric unit (ml (-1) . min (-1) . body weight [BW] (-2/3)). LBW, fat mass (FM), and body fat content (BF %) all were correlated with VO (2) peak, while LBW was the strongest predictor. The relationship between body composition and VO (2) peak seemed quite comparable across different alpha-fibrinogen genotypes. Significant difference was observed between obese and non-obese boys in terms of the proportion of genotypes and frequency of alleles. T1T1 homozygotes had higher risk for obesity. We came to the conclusion that prepubertal obese boys exhibited impaired aerobic fitness compared with their normal weight peers. VO (2) peak is closely related to LBW and independent of FM. This relationship remains constant irrespective of the TaqI alpha-fibrinogen genotypes that may be associated with fatness in boys.

  6. luminous transmittance and phase transition temperature of vo2:ce ...

    African Journals Online (AJOL)

    nb

    68 oC accompanied by dramatic changes in electrical and optical properties has attracted intensive research in this thermochromic material. The phase transition in VO2 has been tailored to suit various applications in devices such as smart.

  7. Genes to predict VO2max trainability: a systematic review.

    Science.gov (United States)

    Williams, Camilla J; Williams, Mark G; Eynon, Nir; Ashton, Kevin J; Little, Jonathan P; Wisloff, Ulrik; Coombes, Jeff S

    2017-11-14

    Cardiorespiratory fitness (VO2max) is an excellent predictor of chronic disease morbidity and mortality risk. Guidelines recommend individuals undertake exercise training to improve VO2max for chronic disease reduction. However, there are large inter-individual differences between exercise training responses. This systematic review is aimed at identifying genetic variants that are associated with VO2max trainability. Peer-reviewed research papers published up until October 2016 from four databases were examined. Articles were included if they examined genetic variants, incorporated a supervised aerobic exercise intervention; and measured VO2max/VO2peak pre and post-intervention. Thirty-five articles describing 15 cohorts met the criteria for inclusion. The majority of studies used a cross-sectional retrospective design. Thirty-two studies researched candidate genes, two used Genome-Wide Association Studies (GWAS), and one examined mRNA gene expression data, in addition to a GWAS. Across these studies, 97 genes to predict VO2max trainability were identified. Studies found phenotype to be dependent on several of these genotypes/variants, with higher responders to exercise training having more positive response alleles than lower responders (greater gene predictor score). Only 13 genetic variants were reproduced by more than two authors. Several other limitations were noted throughout these studies, including the robustness of significance for identified variants, small sample sizes, limited cohorts focused primarily on Caucasian populations, and minimal baseline data. These factors, along with differences in exercise training programs, diet and other environmental gene expression mediators, likely influence the ideal traits for VO2max trainability. Ninety-seven genes have been identified as possible predictors of VO2max trainability. To verify the strength of these findings and to identify if there are more genetic variants and/or mediators, further tightly

  8. VO2 max in an Indian population: a study to understand the role of factors determining VO2 max

    National Research Council Canada - National Science Library

    Nitin, Y M; Sucharita, S; Madhura, M; Thomas, T; Sandhya, T A

    2013-01-01

    ... (body composition and physical activity level). Twenty healthy adult males (18-30 years) underwent detailed anthropometry, physical activity level and modified Bruce protocol for VO2 max assessment...

  9. VO2peak prediction and exercise prescription for pregnant women.

    Science.gov (United States)

    Mottola, Michelle F; Davenport, Margie H; Brun, Chantale R; Inglis, Stuart D; Charlesworth, Sarah; Sopper, Maggie M

    2006-08-01

    The present study was designed to develop and validate a prediction equation for peak oxygen consumption VO2peak) using a progressive treadmill test and to refine the current target HR exercise guidelines for pregnancy (PARmed-X for Pregnancy). One hundred fifty-six women between 16 and 22 wk of gestation performed the test to volitional fatigue (peak exercise test). Data from every fourth subject were used to form the cross-validation group. The women were separated into two age groups; 20-29 (N = 60) and 30-39 (N = 96) yr of age and then further separated into fit (VO2peak at the top 25th percentile), unfit (VO2peak at the bottom 25th percentile), and active (between these two ranges). HR and VO2peak values were used in the regression equation to predict target HR ranges at 60 and 80% VO2peak. The prediction equation (R2 = 0.72, R2adjusted = 0.71 and SEE = 2.7) was compared with cross validation (N = 39; P = 0.78). Fit women had a VO2peak > or = 27.2 mL.kg(-1).min(-1) and > or = 26.1 mL.kg.min for ages 20-29 and 30-39 yr, respectively, representing the top 25th percentile. Unfit women had a VO2peak of pregnant women using a progressive treadmill exercise test. The defined target HR zones based on age and the appropriate fitness levels can be used for exercise prescription in healthy pregnant women.

  10. Peak VO2 and VE/VCO2 slope in betablockers era in patients with heart failure: a Brazilian experience.

    Science.gov (United States)

    Guimarães, Guilherme Veiga; Silva, Mário Sérgio Vaz da; d'Avila, Veridiana Moraes; Ferreira, Silvia Moreira Ayub; Silva, Christiano Pereira; Bocchi, Edimar Alcides

    2008-07-01

    Studies have demonstrated that peak oxygen consumption (peak VO2) and the VE/VCO2 slope are predictors of survival in patients with heart failure (HF). However, with the advent of betablockers in the treatment of HF, the prognostic values of peak VO2 and VE/VCO2 slope have not been fully established. To evaluate the effect of betablocker use on the prognostic value of peak VO2 and VE/VCO2 slope in patients with HF. We studied 391 patients with heart failure, aged 49 +/- 14 years and presenting a left ventricular ejection fraction of 38 +/- 10%. The total number of patients that used (Group I - GI) or did not use (Group II - GII) betablockers was 229 and 162, respectively. All patients were submitted to a cardiopulmonary stress test on a treadmill, using the Naughton protocol. A peak VO2 16 ml x kg(-1) min(-1) categorizes patients with a better mid-term prognosis. Peak VO2 values between > 10 and slope in patients with HF. The prognostic value of the VE/VCO2 slope slope are strong and independent predictors of cardiac events in HF. Thus, both variables remain important survival predictors in patients with HF, especially at the age of betablockers.

  11. Electronic structure and insulating gap in epitaxial VO2 polymorphs

    Directory of Open Access Journals (Sweden)

    Shinbuhm Lee

    2015-12-01

    Full Text Available Determining the origin of the insulating gap in the monoclinic V O2(M1 is a long-standing issue. The difficulty of this study arises from the simultaneous occurrence of structural and electronic transitions upon thermal cycling. Here, we compare the electronic structure of the M1 phase with that of single crystalline insulating V O2(A and V O2(B thin films to better understand the insulating phase of VO2. As these A and B phases do not undergo a structural transition upon thermal cycling, we comparatively study the origin of the gap opening in the insulating VO2 phases. By x-ray absorption and optical spectroscopy, we find that the shift of unoccupied t2g orbitals away from the Fermi level is a common feature, which plays an important role for the insulating behavior in VO2 polymorphs. The distinct splitting of the half-filled t2g orbital is observed only in the M1 phase, widening the bandgap up to ∼0.6 eV. Our approach of comparing all three insulating VO2 phases provides insight into a better understanding of the electronic structure and the origin of the insulating gap in VO2.

  12. Prediction of VO2max in Children and Adolescents Using Exercise Testing and Physical Activity Questionnaire Data.

    Science.gov (United States)

    Black, Nate E; Vehrs, Pat R; Fellingham, Gilbert W; George, James D; Hager, Ron

    2016-01-01

    The purpose of this study was to evaluate the use of a treadmill walk-jog-run exercise test previously validated in adults and physical activity questionnaire data to estimate maximum oxygen consumption (VO2max) in boys (n = 62) and girls (n = 66) aged 12 to 17 years old. Data were collected from Physical Activity Rating (PA-R) and Perceived Functional Ability (PFA) questionnaires, a walk-jog-run submaximal treadmill exercise test, and a maximal graded exercise test. Regression analysis resulted in the development of 2 models to predict VO2max. Submaximal exercise test data were used to build the following model (R2 = .73; SEE = 4.59 mL + kg(- 1) + min(- 1)): VO2max (mL + kg(- 1) + min(- 1)) = 26.890+(5.877 × Gender; 0 = female; 1 = male) - (0.782 × Body Mass Index [BMI])+(0.438 × PFA Score) +(2.712 × Treadmill Speed; mph) +(0.746 × Age) +(0.449 × PA-R Score). Maximal exercise test data were used to build the following model (R2 = .83; SEE = 3.63 mL + kg(- 1) + min(- 1)): VO2max (mL + kg(- 1) + min(- 1)) = 10.716+(1.334 × Maximal Treadmill Grade) +(5.203 × Treadmill Speed; mph) +(3.494 × Gender; 0 = female; 1 = male) - (0.413 × BMI) +(0.249 × PFA). The results of this study demonstrate, for the first time, that regression equations that use both exercise data and physical activity questionnaire data can accurately predict VO2max in youth. The submaximal and maximal exercise tests that use self-selected treadmill speeds can be used to assess cardiorespiratory fitness of youth with a wide range of fitness levels.

  13. Mechanisms of Attenuation of Pulmonary V'O2 Slow Component in Humans after Prolonged Endurance Training.

    Directory of Open Access Journals (Sweden)

    Jerzy A Zoladz

    Full Text Available In this study we have examined the effect of prolonged endurance training program on the pulmonary oxygen uptake (V'O2 kinetics during heavy-intensity cycling-exercise and its impact on maximal cycling and running performance. Twelve healthy, physically active men (mean±SD: age 22.33±1.44 years, V'O2peak 3198±458 mL ∙ min-1 performed an endurance training composed mainly of moderate-intensity cycling, lasting 20 weeks. Training resulted in a decrease (by ~5%, P = 0.027 in V'O2 during prior low-intensity exercise (20 W and in shortening of τp of the V'O2 on-kinetics (30.1±5.9 s vs. 25.4±1.5 s, P = 0.007 during subsequent heavy-intensity cycling. This was accompanied by a decrease of the slow component of V'O2 on-kinetics by 49% (P = 0.001 and a decrease in the end-exercise V'O2 by ~5% (P = 0.005. An increase (P = 0.02 in the vascular endothelial growth factor receptor 2 mRNA level and a tendency (P = 0.06 to higher capillary-to-fiber ratio in the vastus lateralis muscle were found after training (n = 11. No significant effect of training on the V'O2peak was found (P = 0.12. However, the power output reached at the lactate threshold increased by 19% (P = 0.01. The power output obtained at the V'O2peak increased by 14% (P = 0.003 and the time of 1,500-m performance decreased by 5% (P = 0.001. Computer modeling of the skeletal muscle bioenergetic system suggests that the training-induced decrease in the slow component of V'O2 on-kinetics found in the present study is mainly caused by two factors: an intensification of the each-step activation (ESA of oxidative phosphorylation (OXPHOS complexes after training and decrease in the ''additional" ATP usage rising gradually during heavy-intensity exercise.

  14. Validity of VO(2 max) in predicting blood volume: implications for the effect of fitness on aging

    Science.gov (United States)

    Convertino, V. A.; Ludwig, D. A.

    2000-01-01

    A multiple regression model was constructed to investigate the premise that blood volume (BV) could be predicted using several anthropometric variables, age, and maximal oxygen uptake (VO(2 max)). To test this hypothesis, age, calculated body surface area (height/weight composite), percent body fat (hydrostatic weight), and VO(2 max) were regressed on to BV using data obtained from 66 normal healthy men. Results from the evaluation of the full model indicated that the most parsimonious result was obtained when age and VO(2 max) were regressed on BV expressed per kilogram body weight. The full model accounted for 52% of the total variance in BV per kilogram body weight. Both age and VO(2 max) were related to BV in the positive direction. Percent body fat contributed <1% to the explained variance in BV when expressed in absolute BV (ml) or as BV per kilogram body weight. When the model was cross validated on 41 new subjects and BV per kilogram body weight was reexpressed as raw BV, the results indicated that the statistical model would be stable under cross validation (e.g., predictive applications) with an accuracy of +/- 1,200 ml at 95% confidence. Our results support the hypothesis that BV is an increasing function of aerobic fitness and to a lesser extent the age of the subject. The results may have implication as to a mechanism by which aerobic fitness and activity may be protective against reduced BV associated with aging.

  15. luminous transmittance and phase transition temperature of vo2:ce ...

    African Journals Online (AJOL)

    nb

    A two-step increase in transmittance observed in the cooling loop in pure VO2 was found to be suppressed by cerium inclusion. Keywords: vanadium dioxide, luminous transmittance, phase transition temperature. INTRODUCTION. Discovery of novel behavior of vanadium dioxide to undergo a metal-to-insulator phase.

  16. Persistent Electrochemical Performance in Epitaxial VO2(B).

    Science.gov (United States)

    Lee, Shinbuhm; Sun, Xiao-Guang; Lubimtsev, Andrew A; Gao, Xiang; Ganesh, Panchapakesan; Ward, Thomas Z; Eres, Gyula; Chisholm, Matthew F; Dai, Sheng; Lee, Ho Nyung

    2017-04-12

    Discovering high-performance energy storage materials is indispensable for renewable energy, electric vehicle performance, and mobile computing. Owing to the open atomic framework and good room temperature conductivity, bronze-phase vanadium dioxide [VO2(B)] has been regarded as a highly promising electrode material for Li ion batteries. However, previous attempts were unsuccessful to show the desired cycling performance and capacity without chemical modification. Here, we show with epitaxial VO2(B) films that one can accomplish the theoretical limit for capacity with persistent charging-discharging cyclability owing to the high structural stability and unique open pathways for Li ion conduction. Atomic-scale characterization by scanning transmission electron microscopy and density functional theory calculations also reveal that the unique open pathways in VO2(B) provide the most stable sites for Li adsorption and diffusion. Thus, this work ultimately demonstrates that VO2(B) is a highly promising energy storage material and has no intrinsic hindrance in achieving superior cyclability with a very high power and capacity in a Li-ion conductor.

  17. The Model Interoperability Experiment in the Gulf of Maine: A Success Story Made Possible by NetCDF, CF-1.0, NcML, NetCDF-Java, THREDDS, OPeNDAP and MATLAB

    Science.gov (United States)

    Signell, R. P.

    2008-12-01

    The Gulf of Maine Ocean Data Partnership Modeling Committee has been developing a Model Interoperability Experiment in the Gulf of Maine built around the Climate and Forecast (CF-1.0) metadata standard. The goal is to allow scientists to issue common Matlab commands to retrieve geospatially referenced data, regardless of model type. Our starting point was output from six different models: the ROMS, ECOM, POM and FVCOM ocean circulation models, the WRF meteorological model and the WaveWatch III ocean wave model. Although the models all had different grid conventions and were served at different institutions, each group produced NetCDF files, used Matlab for visualization and analysis, and had a standard HTTP 1.1 web server. Only one group used CF-conventions, however, and as a result each group had their own set of analysis and visualization routines to perform nearly identical tasks. The system was designed to achieve interoperability with a minimum of effort on the part of the data providers and data users. To supply data, participants need only place their existing NetCDF files on their own web sites. The data is accessed using the "byte range request" feature of HTTP, utilized in NetCDF-Java. The CF standardization is achieved using a layer of XML (NcML) which also provides virtual aggregation of data. The THREDDS Data Server allows for central cataloging of the dataset, access via the OPeNDAP web service, and for rectilinear grids, access via the OGC Web Coverage Service (WCS) and the NetCDF Subset Services as well. The OPeNDAP + CF standard data can be accessed with our NetCDF-Java based "CF Toolkit for MATLAB". This toolkit works on any MATLAB system without compiling, delivering geospatially referenced model output from all six models using common functions. To further expand the capabilities of CF clients such as the one we have developed, we need to further expand the CF conventions to specify additional common features of model output, including staggered

  18. Comparing VO2max determined by using the relation between heart rate and acceleormetry with submaximal estimated VO2max

    NARCIS (Netherlands)

    Tönis, Thijs; Gorter, K.; Vollenbroek-Hutten, Miriam Marie Rosé; Hermens, Hermanus J.

    AIM: An exploratory study to identify parameters that can be used for estimating a subject’s cardio-respiratory physical fitness level, expressed as VO2max, from a combination of heart rate and 3D accelerometer data. METHODS: Data were gathered from 41 healthy subjects (23 male, 18 female) aged

  19. Repeated Sprint Performance in Male and Female College Athletes Matched for VO2max Relative to Fat Free Mass.

    Science.gov (United States)

    Mageean, Amanda L; Alexander, Ryan P; Mier, Constance M

    The purpose of this study was to examine gender differences in repeated sprint exercise (RSE) performance among male and female athletes matched for VO2max relative to FFM (VO2max FFM). Thirty nine male and female college athletes performed a graded exercise test for VO2max and hydrostatic weighing to determine FFM. From the results, 11 pairs of males and females matched for VO2max FFM (mean ± SD; 58.3 ± 4.3 and 58.9 ± 4.6 ml·kg FFM-1·min-1; men and women, respectively) were identified. On a separate day, matched participants performed a RSE protocol that consisted of five 6-sec cycle sprints with 30-sec recovery periods, followed by 5-min active recovery and a 30-sec all-out sprint. Repeated 6-sec sprint performance did not differ between men and women; both maintained power output (PO) until sprint 4. POFFM (W·kg-1 FFM) did not differ between men and women during the five sprints. During the 30-sec sprint, men achieved a lower peak POFFM than women (11.7 ± 1.5 vs 13.2 ± 1.2); however, the decline in POFFM over 30 sec was greater in women. VO2 (ml·kg FFM-1·min-1) was lower in men during recovery (24.4 ± 3.8 vs 28.7 ± 5.7) and at the beginning (29.2 ± 4.0 vs 34.7 ± 4.9) and end (49.4 ± 5.0 vs 52.3 ± 4.0). of the 30-sec sprint. These data indicate that men and women with similar aerobic capacities do not respond differently to short repeated sprints but may differ in their ability to recover and perform sprints of longer duration.

  20. VO2@RER1.0: a novel submaximal cardiopulmonary exercise index.

    Science.gov (United States)

    Chin, Clifford; Kazmucha, Jeffrey; Kim, Nancy; Suryani, Reny; Olson, Inger

    2010-01-01

    Maximal oxygen consumption (VO2max) is the "gold standard" by which to assess functional capacity; however, it is effort dependent. VO2@RER1.0 is defined when VO2 = VCO2. Between December 22, 1997 and November 9, 2004, 305 pediatric subjects underwent cycle ergometer cardiopulmonary exercise testing, exercised to exhaustion, and reached a peak respiratory exchange ratio > or = 1.10. Group 1 subjects achieved a peak VO2 > or = 80% of predicted VO2max; group 2 subjects achieved a peak VO2 subjects achieved a peak VO2 between 61 and 79% of predicted VO2max. Linear regression analysis was performed for VO2@RER1.0 as a function of predicted VO2 for group 1 subjects. A -2 SD regression line and equation was created. VO2@RER1.0 data from groups 2 and 3 were plotted onto the normative graph. Contingency table and relative-risk analysis showed that an abnormal VO2@RER1.0 predicted an abnormal peak VO2(positive-predictive value 83%, negative-predictive value 85%, sensitivity 84%, and specificity 84%). VO2@RER1.0 is a highly sensitive, specific, and predictive submaximal index of functional capacity. This submaximal index is easy to identify without subjectivity. This index may aid in the evaluation of subjects who cannot exercise to maximal parameters.

  1. Predição da potência aeróbia (VO2máx de crianças e adolescentes em teste incremental na esteira rolante Prediction of aerobic power (VO2max of children and adolescents during an incremental treadmill test

    Directory of Open Access Journals (Sweden)

    Fabiana Andrade Machado

    2013-03-01

    Full Text Available O consumo máximo de oxigênio (VO2máx é a quantidade máxima de energia que pode ser produzida pelo metabolismo aeróbio em determinada unidade de tempo, podendo ser determinado direta ou indiretamente através de equações preditivas. O objetivo deste trabalho foi elaborar uma equação preditiva específica para determinar o VO2máx de meninos de 10 a 16 anos. Quarenta e dois meninos realizaram teste ergoespirométrico de corrida em esteira rolante com velocidade inicial de 9 km/h até exaustão voluntária. Através da regressão linear múltipla foi possível desenvolver a seguinte equação para a determinação indireta do VO2máx: VO2máx (ml/min = -1574,06 + (141,38 x Vpico + (48,34 * Massa corporal, com erro padrão de estimativa = 191,5 ml/min (4,10 ml/kg/min e o coeficiente de determinação = 0,934. Sugerimos que esta é uma fórmula adequada para predizer o VO2máx para esta população.The maximal oxygen uptake (VO2max is the maximal quantity of energy that can be produced by the aerobic metabolism in certain time unity. It can be determined direct or indirectly by predictive equations. The objective of this study was to make a specific predictive equation to determine the VO2max from boys aged 10-16 years-old. Forty-two boys underwent a treadmill running ergospirometric test, with the initial velocity set at 9 km/h, until voluntary exhaustion. By the multiple linear regression was possible to develop the following equation for the indirect determination of the VO2max: VO2max (ml/min = -1574.06 + (141.38 x Vpeak + (48.34 * Body mass, with standard error of estimate = 191.5 ml/min (4.10 ml/kg/min and coefficient of determination = 0.934. We suggest that this formula is appropriate to predict VO2max for this population.

  2. CAN WE CONFIDENTLY STUDY VO2 KINETICS IN YOUNG PEOPLE?

    Directory of Open Access Journals (Sweden)

    Samantha G. Fawkner

    2007-09-01

    Full Text Available The study of VO2 kinetics offers the potential to non-invasively examine the cardiorespiratory and metabolic response to dynamic exercise and limitations to every day physical activity. Its non-invasive nature makes it hugely attractive for use with young people, both healthy and those with disease, and yet the literature, whilst growing with respect to adults, remains confined to a cluster of studies with these special populations. It is most likely that this is partly due to the methodological difficulties involved in studying VO2 kinetics in young people which are not present, or present to a lesser degree, with adults. This article reviews these methodological issues, and explains the main procedures that might be used to overcome them

  3. Is low VO2max/kg in obese heart failure patients indicative of cardiac dysfunction?

    Science.gov (United States)

    Hothi, S S; Tan, D K; Partridge, G; Tan, L B

    2015-04-01

    Low peak O2 consumption (VO2max/kg) has been widely used as an indirect indicator of poor cardiac fitness, and often guides management of patients with severe heart failure (HF). We hypothesized that it should be as good an indicator of cardiac dysfunction in obese and non-obese HF patients. We compared the cardiopulmonary exercise performance and non-invasive hemodynamics of 152 obese (BMI>34 kg.m(-2)) and 173 non-obese (BMI≤32) male HF patients in NYHA classes II and III, with reference to 101 healthy male controls. Their physical and cardiac functional reserves were measured during treadmill exercise testing with standard respiratory gas analyses and CO2 rebreathing to measure cardiac output non-invasively during peak exercise. Data are given as mean ± SD. Obese HF patients with BMI 40.9 ± 7.5 kg·m(-2) (age 56.1 ± 14.0 years, NYHA 2.5 ± 0.5) exercised to acceptable cardiopulmonary limits (peak RER=1.07 ± 0.12), and achieved a mean VO2max/kg of 18.6 ± 5.2 ml·kg(-1)·min(-1), significantly lower than in non-obese HF counterparts (19.9 ± 5.6 ml·kg(-1)·min(-1), P=0.02, age 55.8 ± 10.6 years, BMI 26.6 ± 3.1, NYHA 2.4 ± 0.5, peak RER=1.07 ± 0.09), with both lower than controls (38.5 ± 9.7 ml·kg(-1)·min(-1), PVO2max was higher in obese (2.31 ± 0.69 ml·min(-1)) than non-obese HF patients (1.61 ± 0.49 ml·min(-1), PVO2max/kg is not a generally reliable indicator of cardiac fitness in all patients. Instead, we found that despite having lower VO2max/kg, obese HF patients had stronger hearts capable of generating greater cardiac power than non-obese HF patients of equivalent clinical HF status. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  4. Concurrent validity of the non-exercise based VO2max prediction equation using percentage body fat as a variable in asian Indian adults.

    Science.gov (United States)

    Shenoy, Shweta; Tyagi, Bhupinder S; Sandhu, Jaspal S

    2012-09-21

    Aerobic capacity (VO2max) is highly dependent upon body composition of an individual and body composition varies with ethnicity. The purpose of this study was to check the concurrent validity of the non-exercise prediction equation developed by Jackson and colleagues (1990) using percentage body fat as a variable in Asian Indian adults. One hundred twenty college-aged participants (60 male, 60 female, mean age 22.02 ± 2.29 yrs) successfully completed a maximal graded exercise test (GXT) on a motorized treadmill to assess VO2max. VO2max was then estimated by the non-exercise prediction equation developed by Jackson and colleagues (1990) using percentage body fat. Percentage body fat was calculated by three different models (Sandhu et al's fat mass equation, Durnin-womersley's 4 site percentage body fat and Jackson & Pollock's 4 site percentage body fat) and was used in the above equation. The results of VO2max obtained using "gold standard" treadmill methods were then compared with the three results of VO2max obtained by Jackson et al's equation (using three different models to calculate percentage body fat) and it was determined which equation is best suited to determine percentage body fat and in turn VO2 max for Indian population. Jackson et al's prediction equation overpredicts VO2max in Asian Indian subjects who have a lower VO2max (33.41 ± 14.39 ml/kg/min) than those reported in other age matched populations. percentage body fats calculated by the three equations were significantly different and the correlation coefficient (r) between VO2max calculated by Jackson and colleagues (1990) using Sandhu et al's equation for percentage body fat with VO2 max calculated using treadmill (gold standard) (r = .817) was found slightly more significantly correlated than the other two equations and was not statistically different from the measured value. This study proves that VO2max equation using Sandhu et al's model for percentage body fat yields more

  5. Size- and Interface-Modulated Metal-Insulator Transition in Solution-Synthesized Nanoscale VO2 -TiO2 -VO2 Heterostructures.

    Science.gov (United States)

    Li, Xuefei; Schaak, Raymond E

    2017-12-04

    The M1 form of vanadium dioxide, which exhibits a reversible insulator-metal transition above room temperature, has been incorporated into nanoscale heterostructures through solution-phase epitaxial growth on the tips of rutile TiO2 nanorods. Four distinct classes of VO2 -TiO2 -VO2 nanorod heterostructures are accessible by modulating the growth conditions. Each type of VO2 -TiO2 -VO2 nanostructure has a different insulator-metal transition temperature that depends on the VO2 domain sizes and the TiO2 -VO2 interfacial strain characteristics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Comparison of Blood Cholesterol Profiles Before and After The Measurements of Maximum Aerobic Capacity (VO2max

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    Ar Rasyid Shadiqin

    2013-11-01

    Full Text Available This study is aimed to compare the blood cholesterol profile, before and after the measurement of maximum aerobic capacity (VO2max in the students of Jurusan Pendidikan Olahraga dan Kesehatan (JPOK pada Fakultas Keguruan dan Ilmu Pendidikan (FKIP Universitas Lambung Mangkurat Banjarmasin.Variables in this study consist of lipid profiles, including total cholesterol, high density lipoprotein (HDL, low density lipoprotein (LDL, triglyceride (TG and Maximum Aerobic Capacity (VO2max. The concept of VO2max according to Kent(1994:268: “maximum oxygen volume consumed per minute to show total work capacity, or volume per minute relative to body weight (ml/kg.min”. Operationally, VO2max referred in this study is the maximum volume of oxygen that can be consumed per minute, as measured at progressive run (Bleep Test.The method used in this study is pre-experimental with one group pretest-posttest design. This design implies that a group of subjects are treated for a specific period and the measurements are taken both pre and post.The results: There are changes in blood cholesterol profile after the measurement of maximum oxygen capacity (VO2max, shown by significant decrease of total cholesterol variable, increased HDL, and decreased LDL. Changes in triglyceride variable showed no significant decrease despite the statistic differences. Specific HDL sub-class increasing after exercise is a constructive lipoprotein sub-class whereas LDL is destructive lipoproteins sub-class that might damage the body. Therefore, an increase in HDL and decrease in LDL found in this study appears to be advantageous and consequently might alter the risk of coronary heart disease.

  7. The effect of trial familiarisation on the validity and reproducibility of a field-based self-paced VO2max test.

    Science.gov (United States)

    Lim, W; Lambrick, D; Mauger, A R; Woolley, B; Faulkner, J

    2016-09-01

    The self-paced maximal oxygen uptake (VO2max) test (SPV), which is based on the Borg 6-20 Ratings of Perceived Exertion (RPE) scale, allows participants to self-regulate their exercise intensity during a closed-loop incremental maximal exercise test. As previous research has assessed the utility of the SPV test within laboratory conditions, the purpose to this study was to assess the effect of trial familiarisation on the validity and reproducibility of a field-based, SPV test. In a cross-sectional study, fifteen men completed one laboratory-based graded exercise test (GXT) and three field-based SPV tests. The GXT was continuous and incremental until the attainment of VO2max. The SPV, which was completed on an outdoor 400m athletic track, consisted of five x 2 min perceptually-regulated (RPE11, 13, 15, 17 and 20) stages of incremental exercise. There were no differences in the VO2max reported between the GXT (63.5±10.1 ml·kg(-1)·min(-1)) and each SPV test (65.5±8.7, 65.4±7.0 and 66.7±7.7 ml·kg(-1)·min(-1) for SPV1, SPV2 and SPV3, respectively; P>.05). Similar findings were observed when comparing VO2max between SPV tests (P>.05). High intraclass correlation coefficients were reported between the GXT and the SPV, and between each SPV test (≥.80). Although participants ran faster and further during SPV3, a similar pacing strategy was implemented during all tests. This study demonstrated that a field-based SPV is a valid and reliable VO2max test. As trial familiarisation did not moderate VO2max values from the SPV, the application of a single SPV test is an appropriate stand-alone protocol for gauging VO2max.

  8. The influence of high-velocity circuit resistance training on VO2max and cardiac output.

    Science.gov (United States)

    Petersen, S R; Haennel, R G; Kappagoda, C T; Belcastro, A N; Reid, D C; Wenger, H A; Quinney, H A

    1989-09-01

    In order to investigate the influence of high-velocity circuit resistance training on maximal aerobic power, maximal stroke volume and cardiac output, and blood lactate removal during recovery, 16 habitually active males were blocked on initial VO2max into either training or control groups. The training group completed two (weeks 1 and 2) or three (weeks 3-6) circuits of 10 variable-resistance hydraulic exercise stations at an exercise: relief ratio of 1:2 on alternate days over six weeks. Angular velocities of movement were maintained at approximately 3.1 rad.s-1. Following training, the VO2max was increased (p less than .01) from 4.32 to 4.68 1.min-1. Maximal stroke volume was increased (p less than .05) from 120 to 129 mL and heart rate response to an absolute submaximal exercise load was decreased (p less than .05) from 153 to 146 beats.min-1. As well, enhanced (p less than .01) removal of lactate from the blood was observed during recovery from exhausting exercise. No changes were observed for control subjects. These results indicate that positive alterations in aerobic and cardiovascular function may be achieved consequent to high-velocity circuit resistance training.

  9. How is rating of perceived capacity related to VO2max and what is VO2max at onset of training?

    Science.gov (United States)

    Gjestvang, Christina; Stensrud, Trine; Haakstad, Lene A H

    2017-01-01

    To evaluate how rating of perceived capacity (RPC) is related to maximal oxygen uptake (VO2max) and examine VO2max at onset of training in healthy adults. In total, 125 newly registered fitness centre members, equally men and women, answered the RPC scale and performed a treadmill test for measurement of VO2max. Eligible criteria were VO2max. The mean difference between the two methods were +4.92±1.96 and +6.35±1.96 mL/min/kg VO2 in men and women, respectively. The Pearson correlation coefficient was moderate, with r=0.426 (pVO2max were significant predictors of RPC (pVO2max at onset of fitness centre membership was in men aged 38.7±11.7 and women aged 34.7±9.9, 40.5±7.2 and 35.0±6.0 mL/min/kg, respectively. Estimated VO2max from the RPC scale was 45.7±9.8 and 41.4±10.1 mL/min/kg in men and women, respectively. The RPC seems less accurate at the individual level and may overestimate VO2max. Still, it may be considered useful in large-scale studies.

  10. Comprehensive picture of VO2 from band theory

    KAUST Repository

    Zhu, Zhiyong

    2012-08-28

    The structural, electronic, and magnetic features of the metal-insulator transition from the tetragonal rutile (R) to the monoclinic (M1) phase of VO2 are well reproduced by band theory using the modified Becke-Johnson exchange potential. Based on this description, we identify a tendency for monoclinic charge ordering in the R phase due to electronic correlations as the origin of the phase transition. Whereas, the structural changes are crucial for the gap opening in the M1 phase, spin degeneracy in both phases is stabilized by correlation-induced delocalization of the V3d electrons.

  11. Componente lento do VO2 em crianças durante exercício pesado de corrida: análise com base em diferentes modelos matemáticos Componente lento de VO2 en niños durante ejercicio arduo de carrera: análisis con base en diferentes modelos matemáticos Slow component of VO2 in children during running exercise performed at heavy intensity domain: analysis with different mathematical models

    Directory of Open Access Journals (Sweden)

    Fabiana Andrade Machado

    2006-12-01

    Full Text Available O objetivo deste estudo foi verificar e quantificar a magnitude do componente lento do consumo de oxigênio (CL em crianças submetidas a exercícios de corrida em esteira rolante, com cargas constantes de intensidade acima do limiar de lactato (75%D, utilizando para isso dois modelos de análise: a modelo matemático com três termos exponenciais; e b modelo deltaVO2 6-3min. Participaram do estudo oito crianças do sexo masculino (11,92 ± 0,63 anos; 44,06 ± 13,01kg; 146,63 ± 7,25cm; e níveis de maturação sexual 1 e 2, aparentemente saudáveis, não treinadas, que realizaram em diferentes dias: 1 teste incremental na esteira rolante para a determinação do consumo de oxigênio de pico (VO2pico e do limiar de lactato (LL; e 2 dois testes de carga constante em esteira rolante durante seis minutos na intensidade de 75%delta [75%delta = LL + 0,75 x (VO2pico - LL]. Para determinação do CL utilizaram-se: a modelo matemático de três termos (Exp3; e b a diferença no VO2 entre o sexto e o terceiro minuto de exercício (deltaVO2 6-3min. O CL foi expresso em valores absolutos (ml/min e também como a contribuição percentual do CL para o aumento do VO2 no final do exercício (%CL. O CL determinado pelo modelo Exp3 (129,69 ± 75,71ml/min e 8,4 ± 2,92% foi significantemente maior do que o obtido pelo modelo deltaVO2 6-3min (68,69 ± 102,54ml/min e 3,6 ± 7,34%. Portanto, os valores de CL obtidos em crianças durante o exercício de corrida realizado no domínio pesado (75%delta são dependentes do modelo de análise (Exp3 x deltaVO2 6-3min.El objetivo de este estudio ha sido el de verificar y cuantificar la magnitud del componente lento del consumo de oxígeno (CL en niños, sometidos a ejercicios de carrera en cinta rodante, con cargas constantes de intensidad por encima del límite de lactato (75%delta, utilizando para esto dos modelos de análisis: a modelo matemático con tres términos exponenciales; y b modelo deltaVO2 6-3 min

  12. High-intensity interval training every second week maintains VO2max in soccer players during off-season.

    Science.gov (United States)

    Slettaløkken, Gunnar; Rønnestad, Bent R

    2014-07-01

    Reduced endurance training among semiprofessional soccer players during off-season may have negative effect on game performance during the competition season. This negative effect can be prevented by adding high-intensity interval training (HIT) to normal activity. In this study, we want to compare 2 different frequencies of HIT (5 bouts of 4 minutes on 87-97% peak heart rate) session on maintenance of aerobic fitness among semiprofessional soccer players during a 6-week off-season period. Seventeen male players at second and third highest soccer division in Norway participated. The subjects were randomized into 1 HIT session every second week (HIT 0.5) or 1 HIT session per week (HIT 1). All participants performed a 20-m shuttle run test and a maximal oxygen uptake (VO2max) test on treadmill before and after the training intervention. VO2max (HIT 0.5, 63.4 ± 5.9 ml·kg-1·min-1; HIT 1, 65.6 ± 2.1 ml·kg-1·min-1) and 20-m shuttle run performance (HIT 0.5, 2335 ± 390 m, HIT 1, 2531 ± 106 m) were not different between the groups before the training intervention. VO2max was maintained after the training intervention in both HIT 0.5 and HIT 1 (64.0 ± 5.9 ml·kg-1·min-1 and 64.3 ± 1.3 ml·kg-1·min-1, respectively). There was a reduction in distance covered during the 20-m shuttle run test in HIT 1 and when groups were pooled (-7.9 ± 5.7% and -6.4 ± 7.9%, respectively, p ≤ 0.05). In conclusion, HIT 1 did not maintain VO2max better than HIT 0.5 when added to normal off-season activity. However, performance in 20-m shuttle run, which is a more soccer-specific fitness test than VO2max test, was slightly reduced when both groups was pooled.

  13. Elevated transition temperature in Ge doped VO2 thin films

    Science.gov (United States)

    Krammer, Anna; Magrez, Arnaud; Vitale, Wolfgang A.; Mocny, Piotr; Jeanneret, Patrick; Guibert, Edouard; Whitlow, Harry J.; Ionescu, Adrian M.; Schüler, Andreas

    2017-07-01

    Thermochromic GexV1-xO2+y thin films have been deposited on Si (100) substrates by means of reactive magnetron sputtering. The films were then characterized by Rutherford backscattering spectrometry (RBS), four-point probe electrical resistivity measurements, X-ray diffraction, and atomic force microscopy. From the temperature dependent resistivity measurements, the effect of Ge doping on the semiconductor-to-metal phase transition in vanadium oxide thin films was investigated. The transition temperature was shown to increase significantly upon Ge doping (˜95 °C), while the hysteresis width and resistivity contrast gradually decreased. The precise Ge concentration and the film thickness have been determined by RBS. The crystallinity of phase-pure VO2 monoclinic films was confirmed by XRD. These findings make the use of vanadium dioxide thin films in solar and electronic device applications—where higher critical temperatures than 68 °C of pristine VO2 are needed—a viable and promising solution.

  14. "Tailored" submaximal step test for VO2max prediction in healthy older adults.

    Science.gov (United States)

    Pogliaghi, Silvia; Bellotti, Cecilia; Paterson, Donald H

    2014-04-01

    The authors developed and validated a "tailored" version of the Astrand-Rhyming step test (tA-R) and a new equation for VO2max prediction in older adults (OA). Sixty subjects (age 68 ± 4 yr, 30 male, 30 female) performed their tA-R step test (5-min, 30-cm step, tailored stepping rate) and an incremental cycling test to exhaustion. VO2max was (a) predicted using the standard A-R equation (predicted VO2max), (b) predicted based on the authors' new multiple linear equation (equation VO2max), and (c) directly measured by incremental cycling test (direct VO2max). Agreement among values of VO2max was evaluated by Bland-Altman analysis. The predicted VO2max was not significantly different from the direct VO2max, yet with relatively large imprecision. The equation VO2max allowed more precise as well as accurate predictions of VO2max compared with standard A-R prediction. The "tailored" version of the Astrand-Rhyming step test and the new prediction equation appear suitable for a rapid (5-min), safe (submaximal), accurate, and precise VO2max prediction in healthy OA.

  15. Improving the Accuracy of Predicting Maximal Oxygen Consumption (VO2pk)

    Science.gov (United States)

    Downs, Meghan E.; Lee, Stuart M. C.; Ploutz-Snyder, Lori; Feiveson, Alan

    2016-01-01

    Maximal oxygen (VO2pk) is the maximum amount of oxygen that the body can use during intense exercise and is used for benchmarking endurance exercise capacity. The most accurate method to determineVO2pk requires continuous measurements of ventilation and gas exchange during an exercise test to maximal effort, which necessitates expensive equipment, a trained staff, and time to set-up the equipment. For astronauts, accurate VO2pk measures are important to assess mission critical task performance capabilities and to prescribe exercise intensities to optimize performance. Currently, astronauts perform submaximal exercise tests during flight to predict VO2pk; however, while submaximal VO2pk prediction equations provide reliable estimates of mean VO2pk for populations, they can be unacceptably inaccurate for a given individual. The error in current predictions and logistical limitations of measuring VO2pk, particularly during spaceflight, highlights the need for improved estimation methods.

  16. he time limit of maintaining the running speed at VO2max (TLIM VO2max. A comparative study between trained and untrained

    Directory of Open Access Journals (Sweden)

    Cezar HONCERIU

    2017-03-01

    Full Text Available Specialised literature is very rich in means evaluating of VAM or vVO2max and methods of increasing this physical ability, yet poorer in assessing the limit time of maintaining it (tlimVO2max. tlimVO2max is the running time that an athlete can maintain at VAM. This study assumes that it is possible that trained individuals achieve a tlimVO2max greater than untrained individuals. 14 male persons were involved in this study; they were divided into two groups: trained and untrained. VAM evaluation was done by using the VAMEVAL test. The evaluation of tlimVO2max was done by using the VAMEVAL soft. The results of the study refute the research hypothesis, Group B, that was made up of subjects with a lower VO2max, obtained an average tlimVO2max better than group A, group that consists of athletes and better VO2max subjects.

  17. Utility of a Non-Exercise VO2max Prediction Model for Designing Ramp Test Protocols.

    Science.gov (United States)

    Cunha, F A; Midgley, A; Montenegro, R; Vasconcellos, F; Farinatti, P

    2015-10-01

    This study investigated the validity of determining the final work rates of cycling and walking ramp-incremented maximal cardiopulmonary exercise tests (CPETs) using a non-exercise model to predict maximal oxygen uptake VO2max and the American College of Sports Medicine ACSM's metabolic equations. The validity of using this methodology to elicit the recommended test duration of between 8 and 12 min was then evaluated. First, 83 subjects visited the laboratory once to perform a cycling (n=49) or walking (n=34) CPET to investigate the validity of the methodology. Second, 25 subjects (cycling group: n=13; walking group: n=12) performed a CPET on 2 separate days to test the reliability of CPET outcomes. Observed VO2max was 1.0 ml·kg(-1)·min(-1) lower than predicted in the cycling CPET (P=0.001) and 1.4 ml·kg(-1)·min(-1) lower in the walking CPET (P=0.001). Only one of the 133 conducted CPETs was outside the test duration range of 8-12 min. Test-retest reliability was high for all CPET outcomes, with intraclass correlation coefficients of 0.90 to 0.99. In conclusion, the non-exercise model is a valid and reliable method for establishing the final work rate of cycling and walking CPETs for eliciting test durations of between 8 and 12 min. © Georg Thieme Verlag KG Stuttgart · New York.

  18. Effects of ATP-induced leg vasodilation on VO2 peak and leg O2 extraction during maximal exercise in humans

    DEFF Research Database (Denmark)

    Calbet, J A L; Lundby, C; Sander, M

    2006-01-01

    During maximal whole body exercise VO2 peak is limited by O2 delivery. In turn, it is though that blood flow at near-maximal exercise must be restrained by the sympathetic nervous system to maintain mean arterial pressure. To determine whether enhancing vasodilation across the leg results in higher......) into the right femoral artery at a rate of 80 microg.kg body mass-1.min-1. During near-maximal exercise (92% of VO2 peak), the infusion of ATP increased leg vascular conductance (+43%, P...... O2 delivery and leg VO2 during near-maximal and maximal exercise in humans, seven men performed two maximal incremental exercise tests on the cycle ergometer. In random order, one test was performed with and one without (control exercise) infusion of ATP (8 mg in 1 ml of isotonic saline solution...

  19. High resolution MEMS accelerometers to estimate VO2 and compare running mechanics between highly trained inter-collegiate and untrained runners.

    Science.gov (United States)

    McGregor, Stephen J; Busa, Michael A; Yaggie, James A; Bollt, Erik M

    2009-10-06

    The purposes of this study were to determine the validity and reliability of high resolution accelerometers (HRA) relative to VO(2) and speed, and compare putative differences in HRA signal between trained (T) and untrained (UT) runners during treadmill locomotion. Runners performed 2 incremental VO(2max) trials while wearing HRA. RMS of high frequency signal from three axes (VT, ML, AP) and the Euclidean resultant (RES) were compared to VO(2) to determine validity and reliability. Additionally, axial rms relative to speed, and ratio of axial accelerations to RES were compared between T and UT to determine if differences in running mechanics could be identified between the two groups. Regression of RES was strongly related to VO(2), but T was different than UT (r = 0.96 vs 0.92; p<.001) for walking and running. During walking, only the ratio of ML and AP to RES were different between groups. For running, nearly all acceleration parameters were lower for T than UT, the exception being ratio of VT to RES, which was higher in T than UT. All of these differences during running were despite higher VO(2), O(2) cost, and lower RER in T vs UT, which resulted in no significant difference in energy expenditure between groups. These results indicate that HRA can accurately and reliably estimate VO(2) during treadmill locomotion, but differences exist between T and UT that should be considered when estimating energy expenditure. Differences in running mechanics between T and UT were identified, yet the importance of these differences remains to be determined.

  20. High resolution MEMS accelerometers to estimate VO2 and compare running mechanics between highly trained inter-collegiate and untrained runners.

    Directory of Open Access Journals (Sweden)

    Stephen J McGregor

    Full Text Available BACKGROUND: The purposes of this study were to determine the validity and reliability of high resolution accelerometers (HRA relative to VO(2 and speed, and compare putative differences in HRA signal between trained (T and untrained (UT runners during treadmill locomotion. METHODOLOGY: Runners performed 2 incremental VO(2max trials while wearing HRA. RMS of high frequency signal from three axes (VT, ML, AP and the Euclidean resultant (RES were compared to VO(2 to determine validity and reliability. Additionally, axial rms relative to speed, and ratio of axial accelerations to RES were compared between T and UT to determine if differences in running mechanics could be identified between the two groups. PRINCIPAL FINDINGS: Regression of RES was strongly related to VO(2, but T was different than UT (r = 0.96 vs 0.92; p<.001 for walking and running. During walking, only the ratio of ML and AP to RES were different between groups. For running, nearly all acceleration parameters were lower for T than UT, the exception being ratio of VT to RES, which was higher in T than UT. All of these differences during running were despite higher VO(2, O(2 cost, and lower RER in T vs UT, which resulted in no significant difference in energy expenditure between groups. CONCLUSIONS/SIGNFICANCE: These results indicate that HRA can accurately and reliably estimate VO(2 during treadmill locomotion, but differences exist between T and UT that should be considered when estimating energy expenditure. Differences in running mechanics between T and UT were identified, yet the importance of these differences remains to be determined.

  1. Crystallization Mechanism and Phase Transition Properties of W-doped VO2 Synthesized by Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    LI Yao

    2017-11-01

    Full Text Available VO2 sol was firstly prepared using vanadyl sulfate as a vanadium source by precipitation-peptization method. Then tungsten(W doping vanadium dioxide(W-VO2 was prepared by hydrothermal crystallization of prepared sol with the presence of ammonium metatungstate. The morphologies, crystal structure of the as-prepared samples and phase transition properties were studied by X-ray diffraction(XRD, field emission scanning electron microscope(FESEMand differential scanning calorimetry(DSC analysis. The results indicate that rod-like W-VO2(B crystal with length of 1-2μm and radius of 100-200nm is firstly formed during hydrothermal treatment for 4-48h at 280℃, then the rod-like crystal dissolves gradually and sheet-like or snowflake-like crystal is formed with the phase transition from W-VO2(B to W-VO2(M and eventually, the W-VO2(M crystals can further grow up while the W-VO2(B gradually dissolves; the phase transition temperature of VO2 decreases with the increase in W doping content, and the phase transition temperature of W-VO2(M reduces to about 28℃ when the nominal dopant concentration is 6.0%(atom fraction.The "nucleation-growth-transformation-ripening" mechanism is proposed as the formation mechanism based on the hydrothermal crystallization and morphological evolution process of W-VO2(M.

  2. Effect of W addition on the electrical switching of VO2 thin films

    Directory of Open Access Journals (Sweden)

    Bharathi Rajeswaran

    2016-03-01

    Full Text Available Vanadium Oxide has been a frontrunner in the field of oxide electronics because of its metal-insulator transition (MIT. The interplay of different structures of VO2 has played a crucial role in deciding the magnitude of the first order MIT. Substitution doping has been found to introduce different polymorphs of VO2. Hence the role of substitution doping in stabilizing the competing phases of VO2 in the thin film form remains underexplored. Consequently there have been reports both discounting and approving such a stabilization of competing phases in VO2. It is reported in the literature that the bandwidth of the hysteresis and transition temperature of VO2 can be tuned by substitutional doping of VO2 with W. In this work, we have adopted a novel technique called, Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM to deposit VO2 and W- doped VO2 as thin films. XRD and Raman spectroscopy were used to investigate the role of tungsten on the structure of VO2 thin films. Morphology of the thin films was found to be consisting of globular and porous nanoparticles of size ∼ 20nm. Transition temperature decreased with the addition of W. We found that for 2.0 at % W doping in VO2, the transition temperature has reduced from 68 o C to 25 o C. It is noted that W-doping in the process of reducing the transition temperature, alters the local structure and also increases room temperature carrier concentration.

  3. Evidence of O2 supply-dependent VO2 max in the exercise-trained human quadriceps.

    Science.gov (United States)

    Richardson, R S; Grassi, B; Gavin, T P; Haseler, L J; Tagore, K; Roca, J; Wagner, P D

    1999-03-01

    Maximal O2 delivery and O2 uptake (VO2) per 100 g of active muscle mass are far greater during knee extensor (KE) than during cycle exercise: 73 and 60 ml. min-1. 100 g-1 (2.4 kg of muscle) (R. S. Richardson, D. R. Knight, D. C. Poole, S. S. Kurdak, M. C. Hogan, B. Grassi, and P. D. Wagner. Am. J. Physiol. 268 (Heart Circ. Physiol. 37): H1453-H1461, 1995) and 28 and 25 ml. min-1. 100 g-1 (7.5 kg of muscle) (D. R. Knight, W. Schaffartzik, H. J. Guy, R. Predilleto, M. C. Hogan, and P. D. Wagner. J. Appl. Physiol. 75: 2586-2593, 1993), respectively. Although this is evidence of muscle O2 supply dependence in itself, it raises the following question: With such high O2 delivery in KE, are the quadriceps still O2 supply dependent at maximal exercise? To answer this question, seven trained subjects performed maximum KE exercise in hypoxia [0.12 inspired O2 fraction (FIO2)], normoxia (0.21 FIO2), and hyperoxia (1.0 FIO2) in a balanced order. The protocol (after warm-up) was a square wave to a previously determined maximum work rate followed by incremental stages to ensure that a true maximum was achieved under each condition. Direct measures of arterial and venous blood O2 concentration in combination with a thermodilution blood flow technique allowed the determination of O2 delivery and muscle VO2. Maximal O2 delivery increased with inspired O2: 1.3 +/- 0.1, 1.6 +/- 0.2, and 1.9 +/- 0.2 l/min at 0.12, 0.21, and 1.0 FIO2, respectively (P < 0.05). Maximal work rate was affected by variations in inspired O2 (-25 and +14% at 0.12 and 1.0 FIO2, respectively, compared with normoxia, P < 0.05) as was maximal VO2 (VO2 max): 1.04 +/- 0.13, 1. 24 +/- 0.16, and 1.45 +/- 0.19 l/min at 0.12, 0.21, and 1.0 FIO2, respectively (P < 0.05). Calculated mean capillary PO2 also varied with FIO2 (28.3 +/- 1.0, 34.8 +/- 2.0, and 40.7 +/- 1.9 Torr at 0.12, 0.21, and 1.0 FIO2, respectively, P < 0.05) and was proportionally related to changes in VO2 max, supporting our previous finding that a

  4. The Relationship between Total Blood Cholesterol Level and VO2 max in 6-Minute Walk Test An Analitical Observational Study in Students of Medical Faculty UNISSULA aged 19 to 21 years

    Directory of Open Access Journals (Sweden)

    Rahmaan Innash

    2013-06-01

    Full Text Available The increase in total cholesterol level is a risk factor for coronary heart diseases leading to decrease in fitness. VO2 max is the biggest advocate for heart and lung fitness. There have been few studies conducted on relationship between total cholesterol level and VO2 max. The purpose of the study was to determine the relationship between total colesterol level and VO2 max through the 6-minute walk test. In this Analytical observational study with the population of medical faculty students of 2009, 2010, 2011 included 51 persons aged 19-21 years. Total cholesterol level was measured by specthrophotometer from blood. VO2 max analyzed by the 6-minute walk test. The study resulted in mean VO2 max of 24.48 ml/kg/min, mean of total blood cholesterol of 164.16 mg/dl. Pearson correlation test showed there was a significant correlation between total blood cholesterol level and VO2 max (p < 0.05, with negative correlation r = -0.281. An increase in the blood levels of total cholesterol will decrease physical fitness (VO2 max.

  5. A new non exercise-based VO2max prediction equation for patients with chronic low back pain.

    Science.gov (United States)

    Duque, Ivan Leonardo; Parra, José-Hernán; Duvallet, Alain

    2009-09-01

    INTRODUCTION The measurement of the maximal oxygen uptake as a parameter of cardiorespiratory fitness is useful in exercise prescription in functional restoration programs but this measurement requires the subject's maximal exertion which is not always possible in patients with chronic low back pain. The purpose of this study was to develop a regression equation to predict maximal oxygen uptake based on non-exercise data in adult patients with chronic low back pain. Cross sectional study in which 70 participants completed a maximal graded exercise test in cycle ergometer to assess maximal oxygen uptake. Patients achieved a mean +/- SD value of VO(2)max of 30.8 (+/-7.7) ml kg(-1) min(-1). The regression model included as data of non-exercise the patient's gender, body mass index and the intensity of physical activity during leisure time. Multiple linear regression analysis generated the following formula (R (2) = 38.3, SEE = 6.08 ml kg(-1) min(-1)): VO(2)max (ml kg(-1) min(-1)) = 35.3377 - 0.475411 x BMI + 0.155232 x PALT + 7.97682 x gender; where BMI = body mass index, PALT = physical activity during leisure time, women = 0, men = 1. The Durbin Watson statistic showed no problems with serial autocorrelation (D-W = 1.86). The Kolmogorov-Smirnov normality test demonstrated that the errors are distributed normally. This study provides a new and relatively precise non-exercise regression model to predict VO(2)max in patients with chronic low back pain.

  6. VO2max characteristics of elite female soccer players, 1989-2007.

    Science.gov (United States)

    Haugen, Thomas A; Tønnessen, Espen; Hem, Erlend; Leirstein, Svein; Seiler, Stephen

    2014-05-01

    To quantify VO2max among female competitive soccer players as a function of performance level, field position, and age. In addition, the evolution of VO2max among world-class players over an 18-y period was quantified. Female players (N = 199, 22 ± 4 y, 63 ± 6 kg, height 169 ± 6 cm), including an Olympic winning squad, were tested for VO2max at the Norwegian Olympic Training Center between 1989 and 2007. National-team players had 5% higher VO2max than 1st-division players (P = .042, d = 0.4), 13% higher than 2nd-division players (P VO2max than goalkeepers (P = .048, d = 1.1). No significant differences were observed across outfield players or different age categories. There was a trend toward lower relative VO2max across time epochs. This study demonstrated that VO2max varies across playing-standard level in women's soccer. No significant differences in VO2max were observed across outfield positions and age categories. Over time, there has been a slight negative development in VO2max among elite Norwegian soccer players.

  7. Six weeks of aerobic training improves VO2max and MLSS but does not improve the time to fatigue at the MLSS.

    Science.gov (United States)

    Mendes, Thiago Teixeira; Fonseca, Tatiana Ramos; Ramos, Guilherme Passos; Wilke, Carolina Franco; Cabido, Christian Emmanuel Torres; De Barros, Cristiano Lino Monteiro; Lima, André Maia; Mortimer, Lucas de Avila Carvalho Fleury; de Carvalho, Moisés Vieira; Teixeira, Mauro Martins; Lima, Nilo Resende Viana; Garcia, Emerson Silami

    2013-04-01

    The purpose of this study was to investigate the effects of a 6-week aerobic training period on the time to fatigue (t lim) during exercise performed at the maximal lactate steady state (MLSS). Thirteen untrained male subjects (TG; age 22.5 ± 2.4 years, body mass 72.9 ± 6.7 kg and VO2max 44.9 ± 4.8 mL kg(-1) min(-1)) performed a cycle ergometer test until fatigue at the MLSS power output before and after 6 weeks of aerobic training. A group of eight control subjects (CG; age 25.1 ± 2.4 years, body mass 70.1 ± 9.8 kg and VO2max 45.2 ± 4.1 mL kg(-1) min(-1)) also performed the two tests but did not train during the 6-week period. There were no differences between the groups with respect to the VO2max or MLSS power output (MLSSw) before the treatment period. The VO2max and the MLSSw of the TG increased by 11.2 ± 7.2 % (pre-treatment = 44.9 ± 4.8 vs. post-treatment = 49.8 ± 4.5 mL kg(-1) min(-1)) and 14.7 ± 8.9 % (pre-treatment = 150 ± 27 vs. post-treatment = 171 ± 26 W), respectively, after 6 weeks of training. The results of the CG were unchanged. There were no differences in t lim between the groups or within groups before and after training. Six weeks of aerobic training increases MLSSw and VO2max, but it does not alter the t lim at the MLSS.

  8. VO2 Kinetics and Metabolic Contributions Whilst Swimming at 95, 100, and 105% of the Velocity at VO2 max

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    Ana C. Sousa

    2014-01-01

    Full Text Available A bioenergetical analysis of swimming at intensities near competitive distances is inexistent. It was aimed to compare the transient VO2 kinetics responses and metabolic contributions whilst swimming at different velocities around VO2max⁡. 12 trained male swimmers performed (i an incremental protocol to determine the velocity at VO2max⁡ (vVO2max⁡ and (ii three square wave exercises from rest to 95, 100, and 105% of vVO2max⁡. VO2 was directly measured using a telemetric portable gas analyser and its kinetics analysed through a double-exponential model. Metabolic contributions were assessed through the sum of three energy components. No differences were observed in the fast component response (τ1—15, 18, and 16 s, A1—36, 34, and 37 mL·kg-1·min⁡-1, and Gain—32, 29, and 30 mL·min⁡-1 at 95, 100, and 105% of the vVO2max⁡, resp. but A2 was higher in 95 and 100% compared to 105% intensity (480.76 ± 247.01, 452.18 ± 217.04, and 147.04 ± 60.40 mL·min⁡-1, resp.. The aerobic energy contribution increased with the time sustained (83 ± 5, 74 ± 6, and 59 ± 7% for 95, 100, and 105%, resp.. The adjustment of the cardiovascular and/or pulmonary systems that determine O2 delivery and diffusion to the exercising muscles did not change with changing intensity, with the exception of VO2 slow component kinetics metabolic profiles.

  9. The Effect of Aging on Relationships between Lean Body Mass and VO2max in Rowers.

    Science.gov (United States)

    Kim, Chul-Ho; Wheatley, Courtney M; Behnia, Mehrdad; Johnson, Bruce D

    2016-01-01

    Aging is associated with a fall in maximal aerobic capacity as well as with a decline in lean body mass. The purpose of the study was to investigate the influence of aging on the relationship between aerobic capacity and lean body mass in subjects that chronically train both their upper and lower bodies. Eleven older rowers (58±5 yrs) and 11 younger rowers (27±4 yrs) participated in the study. Prior to the VO2max testing, subjects underwent a dual energy X-ray absorptiometry scan to estimate total lean body mass. Subsequently, VO2max was quantified during a maximal exercise test on a rowing ergometer as well as a semi-recumbent cycle ergometer. The test protocol included a pre-exercise stage followed by incremental exercise until VO2max was reached. The order of exercise modes was randomized and there was a wash-out period between the two tests. Oxygen uptake was obtained via a breath-by-breath metabolic cart (Vmax™ Encore, San Diego, CA). Rowing VO2max was higher than cycling VO2max in both groups (pVO2max from cycling to rowing (pVO2max for both groups (pVO2max between groups disappeared (p>0.05), however, older subjects still demonstrated a lower rowing VO2max relative to younger subjects (pVO2max obtained, however, it appears that VO2max in older subjects may be less influenced by muscle mass than in younger subjects.

  10. Cinética do VO2 durante o exercício realizado na potência crítica em ciclistas e indivíduos não-treinados no ciclismo

    Directory of Open Access Journals (Sweden)

    Renato Aparecido Corrêa Caritá

    2013-06-01

    Full Text Available O objetivo foi analisar a cinética do consumo de oxigênio (VO2 na potência crítica (PC, em indivíduos com diferentes níveis de aptidão aeróbia no ciclismo. Seis ciclistas treinados (GT e sete indivíduos não-treinados (GNT realizaram os seguintes protocolos em cicloergômetro: (a progressivo até a exaustão para determinação do VO2max e sua respectiva intensidade (IVO2max; (b três testes em cargas constantes até a exaustão a 95-110%IVO2max para determinação da PC; e (c um teste em carga constante até a exaustão a 100%PC. No exercício a 100%PC, o componente lento expresso em valor absoluto (GT: 342,4±165,8 ml.min-1 vs. GNT: 571,3±170,1 ml.min-1 e relativo ao aumento do VO2 em exercício (GT: 10,0±4,6% vs. GNT: 26,6±7,3% foram menores para GT. O VO2 ao final do exercício (GT: 89,8±8,4%VO2max vs. GNT: 97,4±2,8%VO2max foi significativamente menor no grupo GT (ρ = 0,045, sendo similar ao VO2max no grupo GNT. Portanto, o nível de aptidão aeróbia pode influenciar as respostas do VO2 ao exercício em PC.

  11. Waist circumference and VO2max are associated with metabolic and hemostatic risk in premenopausal nurses

    NARCIS (Netherlands)

    Elich, H; Riese, H; De Geus, EJC

    In 21 nurses (34.4+/-3.9 yr), VO2max, physical activity, body composition and lifestyle parameters were measured to determine which of these characteristics are related to metabolic and hemostatic risk for cardiovascular disease. Physical activity was assessed with the 7-day recall interview VO2max

  12. Predictors of VO2Peak in children age 6- to 7-years-old

    DEFF Research Database (Denmark)

    Dencker, Magnus; Hermansen, Bianca; Bugge, Anna

    2011-01-01

    This study investigated the predictors of aerobic fitness (VO2PEAK) in young children on a population-base. Participants were 436 children (229 boys and 207 girls) aged 6.7 ± 0.4 yrs. VO2PEAK was measured during a maximal treadmill exercise test. Physical activity was assessed by accelerometers. ...

  13. Epitaxial growth of higher transition-temperature VO2 films on AlN/Si

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    Tetiana Slusar

    2016-02-01

    Full Text Available We report the epitaxial growth and the mechanism of a higher temperature insulator-to-metal-transition (IMT of vanadium dioxide (VO2 thin films synthesized on aluminum nitride (AlN/Si (111 substrates by a pulsed-laser-deposition method; the IMT temperature is TIMT ≈ 350 K. X-ray diffractometer and high resolution transmission electron microscope data show that the epitaxial relationship of VO2 and AlN is VO2 (010 ‖ AlN (0001 with VO2 [101] ‖   AlN   [ 2 1 ̄ 1 ̄ 0 ] zone axes, which results in a substrate-induced tensile strain along the in-plane a and c axes of the insulating monoclinic VO2. This strain stabilizes the insulating phase of VO2 and raises TIMT for 10 K higher than TIMT single crystal ≈ 340 K in a bulk VO2 single crystal. Near TIMT, a resistance change of about four orders is observed in a thick film of ∼130 nm. The VO2/AlN/Si heterostructures are promising for the development of integrated IMT-Si technology, including thermal switchers, transistors, and other applications.

  14. Effects of erythrocyte infusion on VO2max at high altitude

    DEFF Research Database (Denmark)

    Young, Jette Feveile; Sawka, M N; Muza, S R

    1996-01-01

    This study investigated whether autologous erythrocyte infusion would ameliorate the decrement in maximal O2 uptake (VO2max) experienced by lowlanders when they ascend to high altitude. VO2max was measured in 16 men (treadmill running) at sea level (SL) and on the 1st (HA1) and 9th (HA9) days of ...

  15. Voltage-induced switching dynamics based on an AZO/VO2/AZO sandwiched structure

    Science.gov (United States)

    Xiao, Han; Li, Yi; Fang, Baoying; Wang, Xiaohua; Liu, Zhimin; Zhang, Jiao; Li, Zhengpeng; Huang, Yaqin; Pei, Jiangheng

    2017-11-01

    A vanadium dioxide (VO2) thin film was prepared on an Al-doped ZnO (AZO) conductive glass substrate by DC magnetron sputtering and a post-annealing process. The AZO/VO2/AZO sandwiched structure was fabricated on the VO2/AZO composite film using photolithography and a chemical etching process. The composition, microstructure and optical properties of the VO2/AZO composite film were tested. The results showed that the VO2/AZO composite film was poly-crystalline and the AZO layer did not change the preferred growth orientation of VO2. When the voltage was applied on both of the transparent conductive layers of the AZO/VO2/AZO sandwiched structure, an abrupt change in the current was observed at different temperatures. The temperature dependence of I-V characteristic curves for the AZO/VO2/AZO sandwiched structure was analyzed. The phase transition voltage value is 7.5 V at 20 °C and decreases with increasing temperature.

  16. VO2 /TiN Plasmonic Thermochromic Smart Coatings for Room-Temperature Applications.

    Science.gov (United States)

    Hao, Qi; Li, Wan; Xu, Huiyan; Wang, Jiawei; Yin, Yin; Wang, Huaiyu; Ma, Libo; Ma, Fei; Jiang, Xuchuan; Schmidt, Oliver G; Chu, Paul K

    2018-01-19

    Vanadium dioxide/titanium nitride (VO2 /TiN) smart coatings are prepared by hybridizing thermochromic VO2 with plasmonic TiN nanoparticles. The VO2 /TiN coatings can control infrared (IR) radiation dynamically in accordance with the ambient temperature and illumination intensity. It blocks IR light under strong illumination at 28 °C but is IR transparent under weak irradiation conditions or at a low temperature of 20 °C. The VO2 /TiN coatings exhibit a good integral visible transmittance of up to 51% and excellent IR switching efficiency of 48% at 2000 nm. These unique advantages make VO2 /TiN promising as smart energy-saving windows. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Self-assembly and horizontal orientation growth of VO2 nanowires.

    Science.gov (United States)

    Cheng, Chun; Guo, Hua; Amini, Abbas; Liu, Kai; Fu, Deyi; Zou, Jian; Song, Haisheng

    2014-06-26

    Single-crystalline vanadium dioxide (VO2) nanostructures have attracted an intense research interest recently because of their unique single-domain metal-insulator phase transition property. Synthesis of these nanostructures in the past was limited in density, alignment, or single-crystallinity. The assembly of VO2 nanowires (NWs) is desirable for a "bottom-up" approach to the engineering of intricate structures using nanoscale building blocks. Here, we report the successful synthesis of horizontally aligned VO2 NWs with a dense growth mode in the [1-100]quartz direction of a polished x-cut quartz surface using a simple vapor transport method. Our strategy of controlled growth of VO2 NWs promisingly paves the way for designing novel metal-insulator transition devices based on VO2 NWs.

  18. Inclusão do equivalente energético do lactato na regressão VO2-intensidade em corrida horizontal e inclinada (10,5%

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    Victor Machado REIS

    Full Text Available Resumo O estudo teve por objetivo analisar o efeito da adição do equivalente energético do lactato sanguíneo com a medida de VO2 durante a corrida em esteira horizontal (0% e inclinada (10,5%, como forma de estimativa do custo energético da corrida. Treze corredores de meia e longa distância (idade 28,1 ± 4,2 anos; estatura 1,75 ± 0,07 m; massa corporal 65,2 ± 4,9 kg; VO2max 70,3 ± 4,9 ml·kg-1·min-1 cumpriram dois testes em esteira rolante (0% e 10,5% que incluíram vários estágios em intensidade constante. Foram calculadas para cada atleta as regressões VO2-velocidade, bem como regressões alternativas com a adição de um equivalente energético de 3 ml O2 Eq·kg-1·mM [La-] às medições de VO2. Não se verificou interação significativa entre a adição do equivalente do lactato e a inclinação da esteira. A ANOVA indicou um efeito significativo da adição do equivalente do lactato na inclinação da reta de regressão e na estimativa do custo energético. Os tamanhos do efeito obtidos indicam que este efeito é mais forte na corrida horizontal. Estes resultados sugerem que em testes laboratoriais com corredores treinados se deverá considerar a adição dos valores de VO2 com os equivalentes energéticos do lactato.

  19. Validation of a Ramp Running Protocol for Determination of the True VO2max in Mice.

    Science.gov (United States)

    Ayachi, Mohamed; Niel, Romain; Momken, Iman; Billat, Véronique L; Mille-Hamard, Laurence

    2016-01-01

    In the field of comparative physiology, it remains to be established whether the concept of VO2max is valid in the mouse and, if so, how this value can be accurately determined. In humans, VO2max is generally considered to correspond to the plateau observed when VO2 no longer rises with an increase in workload. In contrast, the concept of VO2peak tends to be used in murine studies. The objectives of the present study were to determine whether (i) a continuous ramp protocol yielded a higher VO2peak than a stepwise, incremental protocol, and (ii) the VO2peak measured in the ramp protocol corresponded to VO2max. The three protocols (based on intensity-controlled treadmill running until exhaustion with eight female FVB/N mice) were performed in random order: (a) an incremental protocol that begins at 10 m.min(-1) speed and increases by 3 m.min(-1) every 3 min. (b) a ramp protocol with slow acceleration (3 m.min(-2)), and (c) a ramp protocol with fast acceleration (12 m.min(-2)). Each protocol was performed with two slopes (0 and 25°). Hence, each mouse performed six exercise tests. We found that the value of VO2peak was protocol-dependent (p protocol. In the latter, the presence of a VO2max plateau was associated with the fulfillment of two secondary criteria (a blood lactate concentration >8 mmol.l(-1) and a respiratory exchange ratio >1). The total duration of the 3 m.min(-2) 0° ramp protocol was shorter than that of the incremental protocol. Taken as a whole, our results suggest that VO2max in the mouse is best determined by applying a ramp exercise protocol with slow acceleration and no treadmill slope.

  20. VO2max trainability and high intensity interval training in humans: a meta-analysis.

    Science.gov (United States)

    Bacon, Andrew P; Carter, Rickey E; Ogle, Eric A; Joyner, Michael J

    2013-01-01

    Endurance exercise training studies frequently show modest changes in VO2max with training and very limited responses in some subjects. By contrast, studies using interval training (IT) or combined IT and continuous training (CT) have reported mean increases in VO2max of up to ~1.0 L · min(-1). This raises questions about the role of exercise intensity and the trainability of VO2max. To address this topic we analyzed IT and IT/CT studies published in English from 1965-2012. Inclusion criteria were: 1)≥ 3 healthy sedentary/recreationally active humans VO2max. A total of 334 subjects (120 women) from 37 studies were identified. Participants were grouped into 40 distinct training groups, so the unit of analysis was 40 rather than 37. An increase in VO2max of 0.51 L · min(-1) (95% CI: 0.43 to 0.60 L · min(-1)) was observed. A subset of 9 studies, with 72 subjects, that featured longer intervals showed even larger (~0.8-0.9 L · min(-1)) changes in VO2max with evidence of a marked response in all subjects. These results suggest that ideas about trainability and VO2max should be further evaluated with standardized IT or IT/CT training programs.

  1. Terbium-Doped VO2 Thin Films: Reduced Phase Transition Temperature and Largely Enhanced Luminous Transmittance.

    Science.gov (United States)

    Wang, Ning; Duchamp, Martial; Dunin-Borkowski, Rafal E; Liu, Shiyu; Zeng, XianTing; Cao, Xun; Long, Yi

    2016-01-26

    Vanadium dioxide (VO2) is a well-known thermochromic material with large IR modulating ability, promising for energy-saving smart windows. The main drawbacks of VO2 are its high phase transition temperature (τ(c) = 68°C), low luminous transmission (T(lum)), and weak solar modulating ability (ΔT(sol)). In this paper, the terbium cation (Tb(3+)) doping was first reported to reduce τ(c) and increase T(lum) of VO2 thin films. Compared with pristine VO2, 2 at. % doping level gives both enhanced T(lum) and ΔT(sol) from 45.8% to 54.0% and 7.7% to 8.3%, respectively. The T(lum) increases with continuous Tb(3+) doping and reaches 79.4% at 6 at. % doping level, representing ∼73.4% relative increment compared with pure VO2. This has surpassed the best reported doped VO2 thin films. The enhanced thermochromic properties is meaningful for smart window applications of VO2 materials.

  2. .VO2max is not altered by self-pacing during incremental exercise.

    Science.gov (United States)

    Chidnok, Weerapong; Dimenna, Fred J; Bailey, Stephen J; Burnley, Mark; Wilkerson, Daryl P; Vanhatalo, Anni; Jones, Andrew M

    2013-02-01

    We tested the hypothesis that incremental cycling to exhaustion that is paced using clamps of the rating of perceived exertion (RPE) elicits higher .VO2max values compared to a conventional ramp incremental protocol when test duration is matched. Seven males completed three incremental tests to exhaustion to measure .VO2max. The incremental protocols were of similar duration and included: a ramp test at 30 W min(-1) with constant cadence (RAMP1); a ramp test at 30 W min(-1) with cadence free to fluctuate according to subject preference (RAMP2); and a self-paced incremental test in which the power output was selected by the subject according to prescribed increments in RPE (SPT). The subjects also completed a .VO2max 'verification' test at a fixed high-intensity power output and a 3-min all-out test. No difference was found for .VO2max between the incremental protocols (RAMP1 = 4.33 ± 0.60 L min(-1); RAMP2 = 4.31 ± 0.62 L min(-1); SPT = 4.36 ± 0.59 L min(-1); P > 0.05) nor between the incremental protocols and the peak.VO2max measured during the 3-min all-out test (4.33 ± 0.68 L min(-1)) or the .VO2max measured in the verification test (4.32 ± 0.69 L min(-1)). The integrated electromyogram, blood lactate concentration, heart rate and minute ventilation at exhaustion were not different (P > 0.05) between the incremental protocols. In conclusion, when test duration is matched, SPT does not elicit a higher .VO2max compared to conventional incremental protocols. The striking similarity of .VO2max measured across an array of exercise protocols indicates that there are physiological limits to the attainment of .VO2max that cannot be exceeded by self-pacing.

  3. Estimated V(O2)max from the rockport walk test on a nonmotorized curved treadmill.

    Science.gov (United States)

    Seneli, Rhiannon M; Ebersole, Kyle T; OʼConnor, Kristian M; Snyder, Ann C

    2013-12-01

    The Rockport Walk Test (RWT) is a 1-mile walk used to estimate the maximal volume of oxygen uptake (V(O2)max). The purpose of this study was to validate the RWT on a nonmotorized curved treadmill (CT). Twenty-three healthy adults (10 females; 19-44 years old) participated. One trial of the RWT was performed on a measured indoor track (RWTO) and another on the CT (RWTC) on different days in randomized order. Heart rate (HR) and completion time were used to calculate V(O2)max using 6 different general and gender specific equations from previous research. Subjects also performed a treadmill graded exercise test (GXT), which was used as the criterion measure for V(O2)max. Completion times and HR between the 2 RWT were compared using dependent t-tests. Estimated V(O2)max values were compared between the RWTC, RWTO, and GXT through repeated measures analysis of variance, Pearson's correlations (r), and Bland-Altman's plots. There was no difference between completion times for the RWTO and RWTC but HRs were significantly higher with RWTC. When the same equation was applied to the RWTO and RWTC, there were no similar results. All V(O2)max estimations were different from observed V(O2)max except for the estimation from the relative general Kline et al. equation on the RWTO. Despite high correlations (r = 0.75-0.91), the RWTC underestimated V(O2)max. The RWTC underestimates V(O2)max but may be beneficial if a new equation were created specifically for the CT. With appropriate equations for the CT, the RWTC would provide an alternate form of V(O2)max testing.

  4. PERBEDAAN PENGARUH CIRCUIT TRAINING DAN FARTLEK TRAINING TERHADAP PENINGKATAN VO2MAX DAN INDEKS MASSA TUBUH

    Directory of Open Access Journals (Sweden)

    Muh. Akmal Almy

    2014-04-01

    Full Text Available Penelitian ini bertujuan untuk mengetahui: (1 metode circuit training lebih efektif daripada metode fartlek training dalam meningkatkan VO2Max pada pemain sepakbola (2 Indeks Massa Tubuh (IMT rendah lebih baik/bagus daripada Indeks Massa Tubuh (IMT tinggi terhadap peningkatan VO2 Max pemain sepakbola, (3 Ada kecenderungan interaksi antar kedua kelompok latihan dan Indeks Massa Tubuh (IMT terhadap peningkatan VO2Max. Penelitian ini merupakan penelitian eksperimen dengan rancangan faktorial 2 x 2. Instrumen dalam penelitian ini adalah Multistage Test dan IMT. Hasil penelitian adalah sebagai berikut. (1 terdapat perbedaan pengaruh yang signifikan antara metode circuit training dan metode fartlek training terhadap peningkatan VO2Max pemain sepakbola SSB Putratama Bantul dan SSB Baturetno Bantul usia 16-17 tahun, terbukti dari nilai p = 0.020 < 0.05. (2 terdapat perbedaan pengaruh yang signifikan antara Indeks Massa Tubuh (IMT rendah dan Indeks Massa Tubuh (IMT tinggi terhadap peningkatan VO2Max pemain sepakbola SSB Putratama Bantul dan SSB Baturetno Bantul usia 16-17 tahun, terbukti dari nilai p = 0.080 < 0.05. (3 Terdapat interaksi yang signifikan antara kedua kelompok latihan dan Indeks Massa Tubuh (IMT terhadap peningkatan VO2Max, terbukti dari nilai p = 0.000 < 0.05. Jadi dapat disimpulkan bahwa: (a Metode circuit training lebih efektif meningkatkan VO2Max untuk pemain sepakbola yang mempunyai IMT rendah, (b Metode fartlek training lebih efektif meningkatkan VO2Max untuk pemain sepakbola yang mempunyai IMT tinggi. Kata kunci: Circuit training, fartlek training, VO2Max, IMT, sepakbola.

  5. Sport-specific fitness testing differentiates professional from amateur soccer players where VO2max and VO2 kinetics do not.

    Science.gov (United States)

    Wells, C M; Edwards, A M; Winter, E M; Fysh, M L; Drust, B

    2012-06-01

    The purpose of this study was to identify if sport-specific and cardiopulmonary exercise testing differentiated professional from amateur soccer players. Thirty six men comprising 18 professional (mean±s: age 23.2±2.4 years) and 18 amateur (mean±SD: age 21.1±1.6 years) soccer players participated and performed four tests on separate occasions: 1) a graded exercise test to determine VO2max; 2) four exercise transients from walking to 80%Δ for the determination of VO2 kinetics; 3) the Yo-Yo Intermittent Recovery Test level 2 (Yo-Yo IR2) and 4) a repeated sprint test (RST). The players did not differ in VO2max (professional 56.5±2.9 mL.kg-1.min-1; amateur 55.7±3.5 mL.kg-1.min-1: P=0.484) or VO2 kinetic fundamental measures (τ1 onset, professional 24.5±3.2 s; amateur 24.0±1.8 s: τ1 cessation, professional 28.7±2.8 s; amateur 29.3±3.5 s: P=0.923). However, the amateurs were outperformed in the Yo-Yo IR2 (Professional 966±153 m; Amateur 840±156 m) (P=0.034) and RST (best time, professional 6.46±0.27 s; amateur 6.84±0.24 s, P=0.012). Performance indices derived from field-based sport-specific performance tests identified significant differences between professional and amateur players (P<0.05). However, neither tests of VO2 kinetics nor VO2max differentiated between groups, suggesting laboratory tests of cardiorespiratory parameters are probably less consequential to soccer than sport-specific field-based observations.

  6. High performance of solvothermally prepared VO2(B) as anode for aqueous rechargeable lithium batteries

    OpenAIRE

    Milošević Sanja; Stojković Ivana; Mitrić Miodrag; Cvjetićanin Nikola

    2015-01-01

    The VO2 (B) was synthesized via a simple solvothermal route at 160oC in ethanol. The initial discharge capacity of VO2 (B) anode, in saturated aqueous solution of LiNO3, was 177 mAh g-1 at a current rate of 50 mA g-1. After 50 cycles capacity fade was 4%, but from 20th-50th cycle no capacity drop was observed. The VO2 (B) has shown very good cyclability at current rate of even 1000 mA g-1 with initial discharge capacity of 92 mAh g-1. The excellent electroc...

  7. EVALUATION AND COMPARISON OF VO2MAX ASSESSMENT MODELS IN HIGH SCHOOL STUDENTS

    OpenAIRE

    Lotfali Bolboli; Navid Lotfi; Mostafa Bagheri; Ali Rajabi

    2013-01-01

    The purpose of this study was to evaluation and comparison of VO2max assessment models in students. Thirty students from high schools of Ardabil city were selected randomly and served as subjects in this study (age: 15.73±0.69 year, height: 169.46±8.1 cm, weight: 61.70±9.32 kg). Subjects were divided into two groups. In one group Rockport test was used to estimate their VO2 max and in other group Balk test was used for the same purpose. Also, the VO2max of both groups were examined by a stand...

  8. VV and VO2 defects in silicon studied with hybrid density functional theory

    KAUST Repository

    Christopoulos, Stavros Richard G

    2014-12-07

    The formation of VO (A-center), VV and VO2 defects in irradiated Czochralski-grown silicon (Si) is of technological importance. Recent theoretical studies have examined the formation and charge states of the A-center in detail. Here we use density functional theory employing hybrid functionals to analyze the formation of VV and VO2 defects. The formation energy as a function of the Fermi energy is calculated for all possible charge states. For the VV and VO2 defects double negatively charged and neutral states dominate, respectively.

  9. EVALUATION AND DEVELOPMENT OF THE VO2 OF ATHLETES THAT ATTEND A SOCCER SCHOOL

    Directory of Open Access Journals (Sweden)

    Felipe Bittencourt Oliveira

    2012-11-01

    Full Text Available The goal of this study was to identify the effects from technical and physical activities on the VO2, of male athletes aged 14 to 15, participants of a soccer school, in the municipality of Rio Pardo - RS. The semi-experimental research involved 10 male adolescents. For the VO2 evaluation the 12 minute Cooper test was used. Interval-training work was applied, at which the athletes exercised 75% of their maximum speed, in 60-meter runs. After training for two months (at least two sessions a week the Cooper post-test was applied to check the improvement of the VO2. As results of this study, we can draw the conclusion that all adolescents involved in this training showed considerable improvement in their maximum VO2, especially the 15-year-old teens, who managed to obtain a much higher percentage level.

  10. Dual-band tunable infrared metamaterial absorber with VO2 conformal resonators

    Science.gov (United States)

    Yang, Jingfan; Qu, Shaobo; Ma, Hua; Wang, Jiafu; Pang, Yongqiang

    2017-11-01

    A dual-band tunable infrared metamaterial absorber with VO2 is proposed. This tunable metamaterial absorber is constructed of three individual layers of conformal resonating layer, dielectric layer, and metallic background. The resonator is composed of gold and VO2. The electromagnetic (EM) wave absorption is numerically calculated and the working mechanism is explained by the surface current and LC-circuit model. Due to the fact that the resonator frequency depends on the resonating gold structure, it is found that by partially replacing the gold structure with VO2, the absorption frequency and intensity can be tuned through changing the temperature of VO2 resonate structure. In addition, the proposed method can be applicable to other resonate shapes.

  11. High performance of solvothermally prepared VO2(B as anode for aqueous rechargeable lithium batteries

    Directory of Open Access Journals (Sweden)

    Milošević Sanja

    2015-01-01

    Full Text Available The VO2 (B was synthesized via a simple solvothermal route at 160oC in ethanol. The initial discharge capacity of VO2 (B anode, in saturated aqueous solution of LiNO3, was 177 mAh g-1 at a current rate of 50 mA g-1. After 50 cycles capacity fade was 4%, but from 20th-50th cycle no capacity drop was observed. The VO2 (B has shown very good cyclability at current rate of even 1000 mA g-1 with initial discharge capacity of 92 mAh g-1. The excellent electrochemical performance of VO2 (B was attributed to the stability of micro-nano structures to repeated intercalation /deintercalation process, very good electronic conductivity as well as the very low charge transfer resistance in the aqueous electrolyte. [Projekat Ministarstva nauke Republike Srbije, br. III45014

  12. Associations between VO2max and vitality in older workers: a cross-sectional study

    National Research Council Canada - National Science Library

    Strijk, Jorien E; Proper, Karin I; Klaver, Linda; van der Beek, Allard J; van Mechelen, Willem

    2010-01-01

    .... Since VO2max gives an indication of one's aerobic fitness, which can be improved by increased levels of physical activity, and because feeling fit is one of the main characteristics of vitality...

  13. Body fat, abdominal fat and body fat distribution related to VO(2PEAK) in young children

    DEFF Research Database (Denmark)

    Dencker, Magnus; Wollmer, Per; Karlsson, Magnus K

    2011-01-01

    Abstract Objective. Aerobic fitness, defined as maximum oxygen uptake (VO(2PEAK)), and body fat measurements represent two known risk factors for disease. The purpose of this study was to investigate the relationship between VO(2PEAK) and body fat measurements in young children at a population......-based level. Methods. Cross-sectional study of 225 children (128 boys and 97 girls) aged 8-11 years, recruited from a population-based cohort. Total lean body mass (LBM), total fat mass (TBF), and abdominal fat mass (AFM) were measured by dual-energy x-ray absorptiometry. Body fat was also calculated...... as a percentage of body mass (BF%) and body fat distribution as AFM/TBF. VO(2PEAK) was assessed by indirect calorimetry during maximal exercise test. Results. Significant relationships existed between body fat measurements and VO(2PEAK) in both boys and girls, with Pearson correlation coefficients for absolute...

  14. Predicting maximal aerobic capacity (VO2max) from the critical velocity test in female collegiate rowers.

    Science.gov (United States)

    Kendall, Kristina L; Fukuda, David H; Smith, Abbie E; Cramer, Joel T; Stout, Jeffrey R

    2012-03-01

    The objective of this study was to examine the relationship between the critical velocity (CV) test and maximal oxygen consumption (VO2max) and develop a regression equation to predict VO2max based on the CV test in female collegiate rowers. Thirty-five female (mean ± SD; age, 19.38 ± 1.3 years; height, 170.27 ± 6.07 cm; body mass, 69.58 ± 0.3 1 kg) collegiate rowers performed 2 incremental VO2max tests to volitional exhaustion on a Concept II Model D rowing ergometer to determine VO2max. After a 72-hour rest period, each rower completed 4 time trials at varying distances for the determination of CV and anaerobic rowing capacity (ARC). A positive correlation was observed between CV and absolute VO2max (r = 0.775, p VO2max (r = 0.414, p = 0.040). Based on the significant correlation analysis, a linear regression equation was developed to predict the absolute VO2max from CV and ARC (absolute VO2max = 1.579[CV] + 0.008[ARC] - 3.838; standard error of the estimate [SEE] = 0.192 L·min(-1)). Cross validation analyses were performed using an independent sample of 10 rowers. There was no significant difference between the mean predicted VO2max (3.02 L·min(-1)) and the observed VO2max (3.10 L·min(-1)). The constant error, SEE and validity coefficient (r) were 0.076 L·min(-1), 0.144 L·min(-1), and 0.72, respectively. The total error value was 0.155 L·min(-1). The positive relationship between CV, ARC, and VO2max suggests that the CV test may be a practical alternative to measuring the maximal oxygen uptake in the absence of a metabolic cart. Additional studies are needed to validate the regression equation using a larger sample size and different populations (junior- and senior-level female rowers) and to determine the accuracy of the equation in tracking changes after a training intervention.

  15. Size and composition-controlled fabrication of VO2 nanocrystals by terminated cluster growth

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre; Slack, Jonathan

    2013-05-14

    A physical vapor deposition-based route for the fabrication of VO2 nanoparticles is demonstrated, consisting of reactive sputtering and vapor condensation at elevated pressures. The oxidation of vanadium atoms is an efficient heterogeneous nucleation method, leading to high nanoparticle throughtput. Fine control of the nanoparticle size and composition is obtained. Post growth annealing leads to crystalline VO2 nanoparticles with optimum thermocromic and plasmonic properties.

  16. Patterns of Senescence in Human Cardiovascular Fitness: VO2max in Subsistence and Industrialized Populations

    Science.gov (United States)

    Pisor, Anne C.; Gurven, Michael; Blackwell, Aaron D.; Kaplan, Hillard; Yetish, Gandhi

    2014-01-01

    Objectives This study explores whether cardiovascular fitness levels and senescent decline are similar in the Tsimane of Bolivia and Canadians, as well as other subsistence and industrialized populations. Among Tsimane, we examine whether morbidity predicts lower levels and faster decline of cardiovascular fitness, or whether their lifestyle (e.g., high physical activity) promotes high levels and slow decline. Alternatively, high activity levels and morbidity might counterbalance such that Tsimane fitness levels and decline are similar to those in industrialized populations. Methods Maximal oxygen uptake (VO2max) was estimated using a step test heart rate method for 701 participants. We compared these estimates to the Canadian Health Measures Survey and previous studies in industrialized and subsistence populations. We evaluated whether health indicators and proxies for market integration were associated with VO2max levels and rate of decline for the Tsimane. Results The Tsimane have significantly higher levels of VO2max and slower rates of decline than Canadians; initial evidence suggests differences in VO2max levels between other subsistence and industrialized populations. Low hemoglobin predicts low VO2max for Tsimane women while helminth infection predicts high VO2max for Tsimane men, though results might be specific to the VO2max scaling parameter used. No variables tested interact with age to moderate decline. Conclusions The Tsimane demonstrate higher levels of cardiovascular fitness than industrialized populations, but levels similar to other subsistence populations. The high VO2max of Tsimane is consistent with their high physical activity and few indicators of cardiovascular disease, measured in previous studies. PMID:24022886

  17. Substrate Effect on Optical Properties of Insulator-Metal Transition in VO2 Thin Films

    OpenAIRE

    Radue, E.; Crisman, E.; L. Wang; Kittiwatanakul, S.; Lu, J.; Wolf, S. A.; Wincheski, R.; Lukaszew, R. A.; Novikova, I.

    2012-01-01

    In this paper we used Raman spectroscopy to investigate the optical properties of vanadium dioxide (VO2) thin films during the thermally induced insulating to metallic phase transition. We observed a significant difference in transition temperature in similar VO2 films grown on quartz and sapphire substrates: the film grown on quartz displayed the phase transition at a lower temperature (Tc=50C) compared a film grown on sapphire (Tc=68C). We also investigated differences in the detected Raman...

  18. VO2 thin films and nanoparticles for energy-saving applications in architectural elements

    OpenAIRE

    Garcia, Ivan Aristides Ferreira

    2015-01-01

    Vanadium dioxide (VO2) is a promising material with large interest in construction industry and architecture, due to its thermochromic properties. This material may be used to create "smart" coatings that result in improvements in the buildings energy efficiency, by reducing heat exchanges and, consequently, the need for acclimatization. In this work, VO2 thin films and coatings were produced and tested in laboratory, to apply in architectural elements, such as glass, rooftop tiles and exteri...

  19. Verification Testing to Confirm VO2max in Altitude-Residing, Endurance-Trained Runners.

    Science.gov (United States)

    Weatherwax, R M; Richardson, T B; Beltz, N M; Nolan, P B; Dalleck, L

    2016-06-01

    We sought to explore the utility of the verification trial to confirm individual attainment of 'true' VO2max in altitude-residing, endurance-trained runners during treadmill exercise. 24 elite endurance-trained men and women runners (age=21.5±3.3 yr, ht=174.8±9.3 cm, body mass=60.5±6.7 kg, PR 800 m 127.5±13.1 s) completed a graded exercise test (GXT) trial (VO2max=60.0±5.8 mL·kg(-1)·min(-1)), and returned 20 min after incremental exercise to complete a verification trial (VO2max=59.6±5.7 mL·kg(-1)·min(-1)) of constant load, supramaximal exercise. The incidence of 'true' VO2max confirmation using the verification trial was 24/24 (100%) with all participants revealing differences in VO2max≤3% (the technical error of our equipment) between the GXT and verification trials. These findings support use of the verification trial to confirm VO2max attainment in altitude-residing, endurance-trained runners. © Georg Thieme Verlag KG Stuttgart · New York.

  20. Comparison of VO2max in obese and non-obese young Indian population.

    Science.gov (United States)

    Patkar, Kshitija Umesh; Joshi, Anjali S

    2011-01-01

    Incidence of obesity in early life is increasing nowadays because of faulty food habits and lack of exercise. This study was aimed to find out whether obesity affects cardiorespiratory efficiency of young adults. As VO2max is the most accepted indicator of cardiorespiratory efficiency it was compared in 30 obese and 30 non-obese subjects aged around 18-20 years. VO2mx was estimated by Queen's college step test. Various other parameters measured and calculated are weight, height, BMI, skin fold thickness, percentage body fat, lean body mass, fat mass. The results showed that cardiorespiratory efficiency (absolute VO2max & VO2max/kg lean body mass) was not affected (P > 0.05) in obese group in both sexes. Ability to do exhausting work (VO2max/kg body weight) was less in obese group (P = 0.001) compared to non-obese group & in obese males (P VO2max/kg body weight. Therefore the exercise programs can be best designed to increase caloric expenditure and thus to decrease body fat rather than to improve aerobic fitness.

  1. Comparison of intensities and rest periods for VO2max verification testing procedures.

    Science.gov (United States)

    Nolan, P B; Beaven, M L; Dalleck, L

    2014-11-01

    We sought to determine the incidence of 'true' VO2max confirmation with the verification procedure across different protocols. 12 active participants (men n=6, women n=6) performed in random order 4 different maximal graded exercises tests (GXT) and verification bout protocols on 4 separate days. Conditions for the rest period and verification bout intensity were: A - 105% intensity, 20 min rest; B - 105% intensity, 60 min rest; C - 115% intensity, 20 min rest; D - 115% intensity, 60 min rest. VO2max confirmation (difference between peak VO2 GXT and verification trialVO2max confirmation across all exercise test conditions (intensity effect within recovery 20 min (χ(2) (1)=4.800, pVO2max confirmation with different rest periods. We recommend the use of 105% of the maximal GXT workload and 20 min rest periods when using verification trials to confirm VO2max in normally active populations. © Georg Thieme Verlag KG Stuttgart · New York.

  2. Broadband modulation of terahertz waves through electrically driven hybrid bowtie antenna-VO2 devices.

    Science.gov (United States)

    Han, Chunrui; Parrott, Edward P J; Humbert, Georges; Crunteanu, Aurelian; Pickwell-MacPherson, Emma

    2017-10-05

    Broadband modulation of terahertz (THz) light is experimentally realized through the electrically driven metal-insulator phase transition of vanadium dioxide (VO2) in hybrid metal antenna-VO2 devices. The devices consist of VO2 active layers and bowtie antenna arrays, such that the electrically driven phase transition can be realized by applying an external voltage between adjacent metal wires extended to a large area array. The modulation depth of the terahertz light can be initially enhanced by the metal wires on top of VO2 and then improved through the addition of specific bowties in between the wires. As a result, a terahertz wave with a large beam size (~10 mm) can be modulated within the measurable spectral range (0.3-2.5 THz) with a frequency independent modulation depth as high as 0.9, and the minimum amplitude transmission down to 0.06. Moreover, the electrical switch on/off phase transition depends very much on the size of the VO2 area, indicating that smaller VO2 regions lead to higher modulation speeds and lower phase transition voltages. With the capabilities in actively tuning the beam size, modulation depth, modulation bandwidth as well as the modulation speed of THz waves, our study paves the way in implementing multifunctional components for terahertz applications.

  3. Microwave properties of the thermal metal-semiconductor transition of the polyaniline-VO2 composites

    Science.gov (United States)

    Hachet, L.; Roduit, Ph.; de Chanterac, H.; Belhadj-Tahar, N.; Fourrier-Lamer, Arlette

    2000-06-01

    The purpose of this paper is to report the experimental results on polyaniline-VO2 composites in the 45MHz-18GHz frequencies range versus temperature and VO2 mass concentration. The temperature dependence studied by classical heating and courant pulse and the percolation phenomena study have been carried out in both the semi- conductor state and metallic state. The VO2 metallic oxide is remarkable through a reversible discontinuity of the electric conductivity which can reach five orders of magnitude at a transition temperature generally located at 68 degree(s)C. This transition is associated with the modification from crystal structure VO2 which passes from a quadratic structure (metal state) to a monoclinic structure (semiconductor state) at the temperature Tt. The powder of VO2 sintered in an induction oven. VO2 was dispersed in a matrix of basic polyaniline, with mass rates of 10%, 30%, 50%, 70% and 90% of vanadium oxide. The strong dynamics of the composites beyond the threshold authorizes the use of a current to induce the temperature within the sample. The simulation of multi-layer of Jauman type, with commendable reflection and transmission in the frequencies range 8-12GHz will be shown.

  4. VO2 microcrystals as an advanced smart window material at semiconductor to metal transition

    Science.gov (United States)

    Basu, Raktima; Magudapathy, P.; Sardar, Manas; Pandian, Ramanathaswamy; Dhara, Sandip

    2017-11-01

    Textured VO2(0 1 1) microcrystals are grown in the monoclinic, M1 phase which undergoes a reversible first order semiconductor to metal transition (SMT) accompanied by a structural phase transition to rutile tetragonal, R phase. Around the phase transition, VO2 also experiences noticeable change in its optical and electrical properties. A change in color of the VO2 micro crystals from white to cyan around the transition temperature is observed, which is further understood by absorption of red light using temperature dependent ultraviolet–visible spectroscopic analysis and photoluminescence studies. The absorption of light in the red region is explained by the optical transition between Hubbard states, confirming the electronic correlation as the driving force for SMT in VO2. The thermochromism in VO2 has been studied for smart window applications so far in the IR region, which supports the opening of the band gap in semiconducting phase; whereas there is hardly any report in the management of visible light. The filtering of blue light along with reflection of infrared above the semiconductor to metal transition temperature make VO2 applicable as advanced smart windows for overall heat management of a closure.

  5. Fabrication and temperature-dependent field-emission properties of bundlelike VO2 nanostructures.

    Science.gov (United States)

    Yin, Haihong; Luo, Min; Yu, Ke; Gao, Yanfeng; Huang, Rong; Zhang, Zhengli; Zeng, Min; Cao, Chuanxiang; Zhu, Ziqiang

    2011-06-01

    Bundlelike VO(2)(B) nanostructures were synthesized via a hydrothermal method, and VO(2)(M(1)/R) nanobundles were obtained after a heat-treatment process. Structural characterization shows that these nanobundles are self-assembled by VO(2) nanowires, and VO(2)(M(1)/R) nanobundles have better crystallinity. Temperature-dependent field-emission (FE) measurement indicates that FE properties of these two phases of nanobundles can both be improved by increasing the ambient temperature. Moreover, for the VO(2)(M(1)/R) nanobundles, their FE properties are also strongly dependent on the temperature-induced metal-insulator transitions process. Compared with poor FE properties found in the insulating phase, FE properties were significantly improved by increasing the temperature, and about a three-orders-of-magnitude increasing of the emission current density has been observed at a fixed field of 6 V/μm. Work function measurement and density-functional theory calculations indicated that the decrease of work function with temperature is the main reason that caused the improvement of FE properties. These characteristics make VO(2)(M(1)/R) a candidate material for application of new type of temperature-controlled field emitters, whose emission density can be adjusted by ambient temperature. © 2011 American Chemical Society

  6. Effect of 3-week high-intensity interval training on VO2max, total haemoglobin mass, plasma and blood volume in well-trained athletes.

    Science.gov (United States)

    Menz, Verena; Strobl, Jochen; Faulhaber, Martin; Gatterer, Hannes; Burtscher, Martin

    2015-11-01

    This study examined the haematological adaptations to high-intensity interval training (HIT), i.e. total haemoglobin mass (tHb-mass), blood volume (BV), and plasma volume (PV), and its effects on VO2max in well-trained athletes. Twenty-seven male and eight female well-trained (VO2max 63.7 ± 7.7 ml/min/kg) athletes were randomly assigned to the HIT (HITG, N = 19) or the control group (CG, N = 16). Over a 3-week period, the HITG performed 11 HIT sessions, consisting of four 4-min interval bouts at an exercise intensity of 90-95 % of the individual maximal heart rate (HRmax), separated by 4-min active recovery periods. Before and 5 ± 2 days after the intervention, tHb-mass, BV and PV were determined by the CO-rebreathing method. VO2max was assessed in a laboratory treadmill test. tHb-mass (from 753 ± 124 to 760 ± 121 g), BV (from 5.6 ± 0.8 to 5.6 ± 0.9 l) and PV (from 3.2 ± 0.5 to 3.2 ± 0.5 l) remained unchanged after HIT and did not show an interaction (group × time). Within the HITG, VO2max improved from baseline by +3.5 % (p = 0.011), but remained unchanged in the CG. No interaction (group × time) was seen for VO2max. The HITG showed a significant reduction in HRmax compared to the baseline measurement (-2.3 %, p ≤ 0.001), but HRmax remained unchanged in the CG. There was a significant interaction (group × time) for HRmax (p = 0.006). Also, oxygen pulse significantly increased only in HITG from 22.9 ± 4.4 to 23.9 ± 4.2 ml/beat, with no interaction (p = 0.150). Eleven HIT sessions added to usual training did neither improve VO2max nor haematological parameters compared to the CG.

  7. Consumo máximo de oxígeno (vo2max en bomberos: revisión sistemática de estudios

    Directory of Open Access Journals (Sweden)

    Jimmy Rojas Quirós

    2013-07-01

    Full Text Available Consumo máximo de oxígeno (VO2max en bomberos: revisión sistemática de estudios. El trabajo de bombero es catalogada como una profesión de riesgo, con alto requerimiento físico; en los últimos años el bombero ha adquirido más competencias que la propia de apagar incendios, entre ellas las intervenciones en accidentes de tránsito, incidentes con materiales peligrosos, rescates, fuegos forestales, entre otros. La imagen del bombero tradicional ha dado paso a nuevos profesionales preparados para afrontar todo tipo de desastres por lo que se habla en la actualidad del bombero completo. El objetivo de este estudio fue revisar sistemáticamente la evidencia científica sobre los valores de consumo máximo de oxígeno (VO2max que presentan los bomberos. Se incluyeron un total de 19 estudios, publicados entre los años 2002 y 2012, de las bases de datos de EBSCOhost, SpringerLink, SPORTDiscus, Medline, Embase y Scielo; además de revistas como Journal of Sports Science & Medicine, Occupational Medicine y Psicothema. Se concluye con esta revisión, con base a los resultados de los estudios, que las diferentes poblaciones de bomberos, oscilan un VO2max de 39,20 a 58,21 ml/kg/min, que varía según la condición inicial que tienen los bomberos en los diferentes estudios que proponen los autores; en general se determina que un bombero debe poseer valores de VO2max por encima de los 43 ml/kg/min, lo cual es lo mínimo recomendable para al menos poseer una buena capacidad aeróbica que le permita desenvolverse en sus funciones básicas como bombero.

  8. Verification testing to confirm VO2max attainment in persons with spinal cord injury.

    Science.gov (United States)

    Astorino, Todd A; Bediamol, Noelle; Cotoia, Sarah; Ines, Kenneth; Koeu, Nicolas; Menard, Natasha; Nyugen, Brianna; Olivo, Cassandra; Phillips, Gabrielle; Tirados, Ardreen; Cruz, Gabriela Velasco

    2018-01-22

    Maximal oxygen uptake (VO2max) is a widely used measure of cardiorespiratory fitness, aerobic function, and overall health risk. Although VO2max has been measured for almost 100 yr, no standardized criteria exist to verify VO2max attainment. Studies document that incidence of 'true' VO2max obtained from incremental exercise (INC) can be confirmed using a subsequent verification test (VER). In this study, we examined efficacy of VER in persons with spinal cord injury (SCI). Repeated measures, within-subjects study. University laboratory in San Diego, CA. Ten individuals (age and injury duration = 33.3 ± 10.5 yr and 6.8 ± 6.2 yr) with SCI and 10 able-bodied (AB) individuals (age = 24.1 ± 7.4 yr). Peak oxygen uptake (VO2peak) was determined during INC on an arm ergometer followed by VER at 105 percent of peak power output (% PPO). Gas exchange data, heart rate (HR), and blood lactate concentration (BLa) were measured during exercise. Across all participants, VO2peak was highly related between protocols (ICC = 0.98) and the mean difference was equal to 0.08 ± 0.11 L/min. Compared to INC, VO2peak from VER was not different in SCI (1.30 ± 0.45 L/min vs. 1.31 ± 0.43 L/min) but higher in AB (1.63 ± 0.40 L/min vs. 1.76 ± 0.40 L/min). Data show similar VO2peak between incremental and verification tests in SCI, suggesting that VER confirms VO2max attainment. However, in AB participants completing arm ergometry, VER is essential to validate appearance of 'true' VO2peak.

  9. The role of cadence on the VO2 slow component in cycling and running in triathletes.

    Science.gov (United States)

    Billat, V L; Mille-Hamard, L; Petit, B; Koralsztein, J P

    1999-10-01

    The purpose of this study was to compare the effect of two different types of cyclic severe exercise (running and cycling) on the VO2 slow component. Moreover we examined the influence of cadence of exercise (freely chosen [FF] vs. low frequency [LF]) on the hypothesis that: 1) a stride frequency lower than optimal and 2) a pedalling frequency lower than FF one could induce a larger and/or lower VO2 slow component. Eight triathletes ran and cycled to exhaustion at a work-rate corresponding to the lactate threshold + 50% of the difference between the work-rate associated with VO2max and the lactate threshold (delta 50) at a freely chosen (FF) and low frequency (LF: - 10 % of FF). The time to exhaustion was not significantly different for both types of exercises and both cadences (13 min 39 s, 15 min 43 s, 13 min 32 s, 15 min 05 s for running at FF and LF and cycling at FF and LF, respectively). The amplitude of the VO2 slow component (i.e. difference between VO2 at the last and the 3rd min of the exercise) was significantly smaller during running compared with cycling, but there was no effect of cadence. Consequently, there was no relationship between the magnitude of the VO2 slow component and the time to fatigue for a severe exercise (r = 0.20, p = 0.27). However, time to fatigue was inversely correlated with the blood lactate concentration for both modes of exercise and both cadences (r = - 0.42, p = 0.01). In summary, these data demonstrate that: 1) in subjects well trained for both cycling and running, the amplitude of the VO2 slow component at fatigue was larger in cycling and that it was not significantly influenced by cadence; 2) the VO2 slow component was not correlated with the time to fatigue. If the nature of the linkage between the VO2 slow component and the fatigue process remains unclear, the type of contraction regimen depending on exercise biomechanic characteristics seems to be determinant in the VO2 slow component phenomenon for a same level of

  10. Influence of glycemic control on gain in VO2 peak, in patients with type 2 diabetes enrolled in cardiac rehabilitation after an acute coronary syndrome. The prospective DARE study.

    Science.gov (United States)

    Vergès, Bruno; Patois-Vergès, Bénédicte; Iliou, Marie-Christine; Simoneau-Robin, Isabelle; Bertrand, Jean-Henri; Feige, Jean-Michel; Douard, Hervé; Catargi, Bogdan; Fischbach, Michel

    2015-07-08

    Gain in VO2 peak after cardiac rehabilitation (CR) following an acute coronary syndrome (ACS), is associated with reduced mortality and morbidity. We have previously shown in CR, that gain in VO2 peak is reduced in Type 2 diabetic patients and that response to CR is impaired by hyperglycemia. We set up a prospective multicenter study (DARE) whose primary objective was to determine whether good glycemic control during CR may improve the gain in VO2 peak. Sixty four type 2 diabetic patients, referred to CR after a recent ACS, were randomized to insulin intensive therapy or a control group with continuation of the pre-CR antidiabetic treatment. The primary objective was to study the effect of glycemic control during CR on the improvement of peak VO2 by comparing first the 2 treatment groups (insulin intensive vs. control) and second, 2 pre-specified glycemic control groups according to the final fructosamine level (below and above the median). At the end of the CR program, the gain in VO2 peak and the final fructosamine level (assessing glycemic level during CR) were not different between the 2 treatment groups. However, patients who had final fructosamine level below the median value, assessing good glycemic control during CR, showed significantly higher gain in VO2 peak (3.5 ± 2.4 vs. 1.7 ± 2.4 ml/kg/min,p = 0.014) and ventilatory threshold (2.7 ± 2.5 vs. 1.2 ± 1.9 ml/kg/min,p = 0.04) and a higher proportion of good CR-responders (relative gain in VO2 peak ≥ 16 %): 66 % vs. 36 %, p = 0.011. In multivariate analysis, gain in VO2 peak was associated with final fructosamine level (p = 0.010) but not with age, gender, duration of diabetes, type of ACS, insulin treatment or basal fructosamine. The DARE study shows that, in type 2 diabetes, good glycemic control during CR is an independent factor associated with gain in VO2 peak. This emphasizes the need for good glycemic control in CR for type 2 diabetic patients. Trial

  11. VO2max trainability and high intensity interval training in humans: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Andrew P Bacon

    Full Text Available Endurance exercise training studies frequently show modest changes in VO2max with training and very limited responses in some subjects. By contrast, studies using interval training (IT or combined IT and continuous training (CT have reported mean increases in VO2max of up to ~1.0 L · min(-1. This raises questions about the role of exercise intensity and the trainability of VO2max. To address this topic we analyzed IT and IT/CT studies published in English from 1965-2012. Inclusion criteria were: 1≥ 3 healthy sedentary/recreationally active humans <45 yrs old, 2 training duration 6-13 weeks, 3 ≥ 3 days/week, 4 ≥ 10 minutes of high intensity work, 5 ≥ 1:1 work/rest ratio, and 6 results reported as mean ± SD or SE, ranges of change, or individual data. Due to heterogeneity (I(2 value of 70, statistical synthesis of the data used a random effects model. The summary statistic of interest was the change in VO2max. A total of 334 subjects (120 women from 37 studies were identified. Participants were grouped into 40 distinct training groups, so the unit of analysis was 40 rather than 37. An increase in VO2max of 0.51 L · min(-1 (95% CI: 0.43 to 0.60 L · min(-1 was observed. A subset of 9 studies, with 72 subjects, that featured longer intervals showed even larger (~0.8-0.9 L · min(-1 changes in VO2max with evidence of a marked response in all subjects. These results suggest that ideas about trainability and VO2max should be further evaluated with standardized IT or IT/CT training programs.

  12. Associations between VO2max and vitality in older workers: a cross-sectional study.

    Science.gov (United States)

    Strijk, Jorien E; Proper, Karin I; Klaver, Linda; van der Beek, Allard J; van Mechelen, Willem

    2010-11-09

    To prevent early exit from work, it is important to study which factors contribute to healthy ageing. One concept that is assumed to be closely related to, and therefore may influence healthy ageing, is vitality. Vitality consists of both a mental and a physical component, and is characterised by a perceived high energy level, decreased feelings of fatigue, and feeling fit. Since VO2max gives an indication of one's aerobic fitness, which can be improved by increased levels of physical activity, and because feeling fit is one of the main characteristics of vitality, it is hypothesised that VO2max is related to vitality. Therefore, the aim of this study was to investigate the associations between VO2max and vitality. In 427 older workers (aged 45 + years) participating in the Vital@Work study, VO2max was estimated at baseline using the 2-km UKK walk test. Vitality was measured by both the UWES Vitality Scale and the RAND-36 Vitality Scale. Associations were analysed using linear regression analyses. The linear regression models, adjusted for age, showed a significant association between VO2max and vitality measured with the RAND-36 Vitality Scale (β = 0.446; 95% CI: 0.220-0.673). There was no significant association between VO2max and vitality measured with the UWES (β = -0.006; 95% CI:-0.017 - 0.006), after adjusting for age, gender and chronic disease status. VO2max was associated with a general measure of vitality (measured with the RAND-36 Vitality Scale), but not with occupational health related vitality (measured with the UWES Vitality Scale). The idea that physical exercise can be used as an effective tool for improving vitality was supported in this study. NTR1240.

  13. Evidence of cardiac functional reserve upon exhaustion during incremental exercise to determine VO2max.

    Science.gov (United States)

    Elliott, Adrian D; Skowno, Justin; Prabhu, Mahesh; Noakes, Timothy David; Ansley, Les

    2015-01-01

    There remains considerable debate regarding the limiting factor(s) for maximal oxygen uptake (VO2max). Previous studies have shown that the central circulation may be the primary limiting factor for VO2max and that cardiac work increases beyond VO2max. We sought to evaluate whether the work of the heart limits VO2max during upright incremental cycle exercise to exhaustion. Eight trained men completed two incremental exercise trials, each terminating with exercise at two different rates of work eliciting VO2max (MAX and SUPRAMAX). During each exercise trial we continuously recorded cardiac output using pulse-contour analysis calibrated with a lithium dilution method. Intra-arterial pressure was recorded from the radial artery while pulmonary gas exchange was measured continuously for an assessment of oxygen uptake. The workload during SUPRAMAX (mean±SD: 346.5±43.2 W) was 10% greater than that achieved during MAX (315±39.3 W). There was no significant difference between MAX and SUPRAMAX for Q (28.7 vs 29.4 L/min) or VO2 (4.3 vs 4.3 L/min). Mean arterial pressure was significantly higher during SUPRAMAX, corresponding to a higher cardiac power output (8.1 vs 8.5 W; p<0.06). Despite similar VO2 and Q, the greater cardiac work during SUPRAMAX supports the view that the heart is working submaximally at exhaustion during an incremental exercise test (MAX). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  14. of a field-based self-paced VO 2 max test

    Directory of Open Access Journals (Sweden)

    W Lim

    2016-08-01

    Full Text Available The self-paced maximal oxygen uptake (VO 2 max test (SPV, which is based on the Borg 6-20 Ratings of Perceived Exertion (RPE scale, allows participants to self-regulate their exercise intensity during a closed-loop incremental maximal exercise test. As previous research has assessed the utility of the SPV test within laboratory conditions, the purpose to this study was to assess the effect of trial familiarisation on the validity and reproducibility of a field-based, SPV test. In a cross-sectional study, fifteen men completed one laboratory-based graded exercise test (GXT and three field-based SPV tests. The GXT was continuous and incremental until the attainment of VO 2 max. The SPV, which was completed on an outdoor 400m athletic track, consisted of five x 2 min perceptually-regulated (RPE11, 13, 15, 17 and 20 stages of incremental exercise. There were no differences in the VO 2 max reported between the GXT (63.5±10.1 ml∙kg-1∙min-1 and each SPV test (65.5±8.7, 65.4±7.0 and 66.7±7.7 ml∙kg-1∙min-1 for SPV1, SPV2 and SPV3, respectively; P>.05. Similar findings were observed when comparing VO 2 max between SPV tests (P>.05. High intraclass correlation coefficients were reported between the GXT and the SPV, and between each SPV test (≥.80. Although participants ran faster and further during SPV3, a similar pacing strategy was implemented during all tests. This study demonstrated that a field-based SPV is a valid and reliable VO 2 max test. As trial familiarisation did not moderate VO 2 max values from the SPV, the application of a single SPV test is an appropriate stand-alone protocol for gauging VO 2 max.

  15. Reprodutibilidade do VO2Máx estimado na corrida pela frequência cardíaca e consumo de oxigênio de reserva Reliability of VO2Max estimated in treadmill running by heart rate reserve and power output

    Directory of Open Access Journals (Sweden)

    Tony Meireles Santos

    2012-03-01

    Full Text Available Objetivou-se comparar os efeitos de utilização da frequência cardíaca máxima medida (FCpico vs. predita (FC Predita na estimativa do VO2Máx em esteira pelo método de FC e VO2 de reserva. Dezoito homens (27,5 ± 7,1 anos, 73,7 ± 12,6 kg, 174,8 ± 10,2 cm realizaram na primeira visita um teste progressivo máximo para determinar a FCpico. Nas duas visitas seguintes foram realizados os testes aeróbios submáximos em esteira com estágio de 6 min a 75% da FC de reserva. O VO2Máx foi estimado pelo uso conjunto das equações de FC, VO2 de reserva e equação de corrida do ACSM. Não foi observada diferença significativa (teste t entre as estimativas de VO2Máx a partir da FCpredita e FCpico. O coeficiente de correlação intraclasse e erro típico da medida utilizando FCpredita e FCpico foram 0,89, 2,43 mL.kg-1.min-1 (5% e 0,83, 2,43 mL.kg-1.min-1 (4,9%, respectivamente. O uso da abordagem estimada para determinação da FC máxima mostrou-se adequado para a determinação do VO2Máx com um pequeno erro típico da medida.The objective was to determine the reliability of the VO2Max estimate on a treadmill using the measured (HRpeak vs. the predicted (HRpredicted maximum heart rate (HR. Eighteen men (27.5 ± 7.1 years, 73.7± 12.6 kg, 174.8 ± 10.2 cm performed, in the first visit, a progressive test to determine the HRpeak. In the two following visits, submaximal aerobic tests were performed on a treadmill with a 6 min at 75% HR reserve. VO2Max was estimated by means of the equations of HR, VO2 reserve and the ACSM running equation. The intraclass correlation coefficient and the typical error of measurement using HRPredicted and HRpeak were 0.89, 2.43 ml.kg-1.min-1 (5% and 0.83, 2.43 mL.kg-1.min-1 (4.9%, respectively. There was no significant difference (t test between the estimates of VO2Max from the HRpeak and HRpredicted. The use of the HRpredicted was considered appropriate for VO2Max estimation, with a small typical error of

  16. VO2+ ions in zinc lead borate glasses studied by EPR and optical absorption techniques.

    Science.gov (United States)

    Prakash, P Giri; Rao, J Lakshmana

    2005-09-01

    Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO-PbO-B2O3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in zinc lead borate glasses were present in octahedral sites with tetragonal compression and belong to C4V symmetry. The spin-Hamiltonian parameters g and A are found to be independent of V2O5 content and temperature but changing with ZnO content. The decrease in Deltag( parallel)/Deltag( perpendicular) value with increase in ZnO content indicates that the symmetry around VO2+ ions is more octahedral. The decrease in intensity of EPR signal above 10 mol% of V2O5 is attributed to a fall in the ratio of the number of V4+ ions (N4) to the number of V5+ ions (N5). The number of spins (N) participating in resonance was calculated as a function of temperature for VO2+ doped zinc lead borate glass sample and the activation energy was calculated. From the EPR data, the paramagnetic susceptibility was calculated at various temperatures and the Curie constant was evaluated from the 1/chi-T graph. The optical absorption spectra show single absorption band due to VO2+ ions in tetragonally distorted octahedral sites.

  17. Scaling of VO2max and its relationship with insulin resistance in children.

    Science.gov (United States)

    Ahn, Bumsoo; McMurray, Robert; Harrell, Joanne

    2013-02-01

    The relationship between insulin resistance (HOMA-IR), percent body fat, and aerobic fitness (VO2max per unit fat free mass; mL/kgFFM/min) was examined in 1,710 children. Percent body fat was estimated from sum of skinfolds, and VO2max was estimated from submaximal cycle ergometer tests. Overnight fasting blood samples were obtained. VO2max (mL/kgFFM/min) and percent body fat were correlated with HOMA-IR (r = -0.076, p VO2max in units of mL/kg/min (r = -0.264, p VO2max in mL/kg/min was used, a progressive increase in HOMA-IR was found with decreasing fitness (p < .05). However, when mL/kgFFM/min was used, HOMA-IR scores remained similar between moderate-fit and low-fit group. The stronger association between aerobic fitness (mL/kg/min) and HOMA-IR is partially due to the significant association of fat mass to HOMA-IR. Therefore, our recommendation is to express aerobic fitness in units of mL/kgFFM/min to eliminate the confounding factor of adiposity and better understand the influence of muscle on insulin resistance.

  18. Supercapacitors based on two dimensional VO2 nanosheet electrodes in organic gel electrolyte

    KAUST Repository

    Rakhi, R.B.

    2016-10-16

    VO2 is a low band-gap semiconductor with relatively high conductivity among transition metal oxides, which makes it an interesting material for supercapacitor electrode applications. The performance of VO2 as supercapacitor electrode in organic electrolytes has never been reported before. Herein, two-dimensional nanosheets of VO2 are prepared by the simultaneous solution reduction and exfoliation from bulk V2O5 powder by hydrothermal method. A specific capacitance of 405 Fg−1 is achieved for VO2 based supercapacitor in an organic electrolyte, in three electrode configuration. The symmetric capacitor based on VO2 nanosheet electrodes and the liquid organic electrolyte exhibits an energy density of 46 Wh kg−1 at a power density of 1.4 kW kg−1 at a constant current density of 1 Ag−1. Furthermore, flexible solid-state supercapacitors are fabricated using same electrode material and Alumina-silica based gel electrolyte. The solid-state device delivers a specific capacitance of 145 Fg−1 and a device capacitance of 36 Fg−1 at a discharge current density of 1 Ag−1. Series combination of three solid state capacitors is capable of lighting up a red LED for more than 1 minute.

  19. Switching VO2 Single Crystals and Related Phenomena: Sliding Domains and Crack Formation

    Directory of Open Access Journals (Sweden)

    Bertina Fisher

    2017-05-01

    Full Text Available VO2 is the prototype material for insulator–metal transition (IMT. Its transition at TIMT = 340 K is fast and consists of a large resistance jump (up to approximately five orders of magnitude, a large change in its optical properties in the visible range, and symmetry change from monoclinic to tetragonal (expansion by 1% along the tetragonal c-axis and 0.5% contraction in the perpendicular direction. It is a candidate for potential applications such as smart windows, fast optoelectronic switches, and field-effect transistors. The change in optical properties at the IMT allows distinguishing between the insulating and the metallic phases in the mixed state. Static or dynamic domain patterns in the mixed-state of self-heated single crystals during electric-field induced switching are in strong contrast with the percolative nature of the mixed state in switching VO2 films. The most impressive effect—so far unique to VO2—is the sliding of narrow semiconducting domains within a metallic background in the positive sense of the electric current. Here we show images from videos obtained using optical microscopy for sliding domains along VO2 needles and confirm a relation suggested in the past for their velocity. We also show images for the disturbing damage induced by the structural changes in switching VO2 crystals obtained for only a few current–voltage cycles.

  20. Relationship between running kinematic changes and time limit at vVO2max

    Directory of Open Access Journals (Sweden)

    Leonardo De Lucca

    2012-06-01

    Exhaustive running at maximal oxygen uptake velocity (vVO2max can alter running kinematic parameters and increase energy cost along the time. The aims of the present study were to compare characteristics of ankle and knee kinematics during running at vVO2max and to verify the relationship between changes in kinematic variables and time limit (Tlim. Eleven male volunteers, recreational players of team sports, performed an incremental running test until volitional exhaustion to determine vVO2max and a constant velocity test at vVO2max. Subjects were filmed continuously from the left sagittal plane at 210 Hz for further kinematic analysis. The maximal plantar flexion during swing (p<0.01 was the only variable that increased significantly from beginning to end of the run. Increase in ankle angle at contact was the only variable related to Tlim (r=0.64; p=0.035 and explained 34% of the performance in the test. These findings suggest that the individuals under study maintained a stable running style at vVO2max and that increase in plantar flexion explained the performance in this test when it was applied in non-runners.

  1. Memristive devices from porous silicon - ZnO/VO2 nanocomposites

    Science.gov (United States)

    Ocampo, O.; Antúnez, E. E.; Agarwal, V.

    2015-12-01

    As metal oxides act as an active media for oxygen vacancies transport after their infiltration/confinement in the submicron porous structure, we report the memristive device fabrication from nanostructured porous silicon - metal oxide (ZnO and VO2) composites. Scanning electron microscopy and X-ray diffraction were used for morphological and structural characterization, respectively. Predominant crystal phase of metal oxides was found to be wurtzite for ZnO and monoclinic for VO2. Electrical characterization reveals that both devices present symmetrical zero-crossing pinched hysteresis curves, typical of memristive systems. Although both the devices reveal significant endurance and stable switching ratio, ZnO-based device exhibits relatively better stability and 86% higher resistive switching ratio with respect to VO2-based device. The proposed memristive devices have potential applications as practical and economical structures that could be integrated in current silicon based microtechnology.

  2. Hybrid metamaterial switching for manipulating chirality based on VO2 phase transition

    Science.gov (United States)

    Lv, T. T.; Li, Y. X.; Ma, H. F.; Zhu, Z.; Li, Z. P.; Guan, C. Y.; Shi, J. H.; Zhang, H.; Cui, T. J.

    2016-01-01

    Polarization manipulations of electromagnetic waves can be obtained by chiral and anisotropic metamaterials routinely, but the dynamic and high-efficiency modulations of chiral properties still remain challenging at the terahertz range. Here, we theoretically demonstrate a new scheme for realizing thermal-controlled chirality using a hybrid terahertz metamaterial with embedded vanadium dioxide (VO2) films. The phase transition of VO2 films in 90° twisted E-shaped resonators enables high-efficiency thermal modulation of linear polarization conversion. The asymmetric transmission of linearly polarized wave and circular dichroism simultaneously exhibit a pronounced switching effect dictated by temperature-controlled conductivity of VO2 inclusions. The proposed hybrid metamaterial design opens exciting possibilities to achieve dynamic modulation of terahertz waves and further develop tunable terahertz polarization devices. PMID:27000427

  3. Enhanced luminous transmittance of thermochromic VO2 thin film patterned by SiO2 nanospheres

    Science.gov (United States)

    Zhou, Liwei; Liang, Jiran; Hu, Ming; Li, Peng; Song, Xiaolong; Zhao, Yirui; Qiang, Xiaoyong

    2017-05-01

    In this study, an ordered SiO2 nanosphere array coated with vanadium dioxide (VO2) has been fabricated to enhance transmittance with the potential application as an energy-efficient coating in the field of smart windows. SiO2 arrays were formed using the methods of self-assembly, and VO2 thin films were prepared by rapid thermal annealing (RTA) of sputtered vanadium films. VO2@SiO2 arrays were characterized by scanning electron microscopy, X-ray diffraction, a four-point probe, and UV-vis-NIR spectrophotometry. Compared with the planar films, the films deposited on 300 nm diameter SiO2 nanospheres can offer approximately 18% enhancement of luminous transmission (Tlum) because the diameter is smaller than the given wavelength and the protuberance of the surface array behaves as a gradation of refractive index producing antireflection. The solar regulation efficiency was not much deteriorated.

  4. Photoluminescence response of colloidal quantum dots on VO2 film across metal to insulator transition.

    Science.gov (United States)

    Kuznetsov, Sergey N; Cheremisin, Alexander B; Stefanovich, Genrikh B

    2014-01-01

    We have proposed a method to probe metal to insulator transition in VO2 measuring photoluminescence response of colloidal quantum dots deposited on the VO2 film. In addition to linear luminescence intensity decrease with temperature that is well known for quantum dots, temperature ranges with enhanced photoluminescence changes have been found during phase transition in the oxide. Corresponding temperature derived from luminescence dependence on temperature closely correlates with that from resistance measurement during heating. The supporting reflectance data point out that photoluminescence response mimics a reflectance change in VO2 across metal to insulator transition. Time-resolved photoluminescence study did not reveal any significant change of luminescence lifetime of deposited quantum dots under metal to insulator transition. It is a strong argument in favor of the proposed explanation based on the reflectance data. 71.30. + h; 73.21.La; 78.47.jd.

  5. Thermal induced tunability of surface plasmon resonance in Au-VO 2 nano-photonics

    Science.gov (United States)

    Maaza, M.; Nemraoui, O.; Sella, C.; Beye, A. C.; Baruch-Barak, B.

    2005-10-01

    A new class of nano-photonics for possible χ3( ω) applications have been synthesized by pulsed laser ablation and optically characterized. Compared to standard nano-composites exhibiting an exalted effective χ3( ω) due to the enhancement of the local electric field, these Au-VO 2 nano-composites display an additional reversibly tunable surface plasmon frequency under external temperature stimuli. This is due to the semi-conducting/metallic first order transition of the host VO 2 matrix. The nano-gold surface plasmon wavelength shifts reversibly from 645 to 598 nm when the Au-VO 2 nano-composites temperature varies from 25 to 120 °C. Even if the spectral shift is not extensively large, such a tunability is positively genuine.

  6. Fabrication of VO2 (B Nanobelts and Their Application in Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Shibing Ni

    2011-01-01

    Full Text Available VO2 (B nanobelts have been successfully synthesized via a simple hydrothermal route. The products were characterized by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, and Raman spectrum. These nanobelts are of rectangular cross-section with mean length about 1 μm, mean width about 80 nm, and mean thickness about 50 nm. The as-synthesized VO2 nanobelts were assembled as the cathode electrodes of lithium ion batteries. Their electrochemical properties were studied by conventional charge/discharge tests, which show an initial discharge capacity of 321 mAh g−1 with voltage plateau near 2.5 V. These results indicated that such hydrothermally synthesized VO2 (B nanobelts could be an ideal candidate of cathode material for lithium ion battery.

  7. Thermally tunable broadband omnidirectional and polarization-independent super absorber using phase change material VO2

    Directory of Open Access Journals (Sweden)

    Zhejun Liu

    Full Text Available In this letter, we numerically demonstrate a thermally tunable super absorber by using phase change material VO2 as absorbing layer in metal-insulator-metal structure. An omnidirectional super absorption at λ=2.56μm can be realized by heating the patterned grating VO2 film due to magnetic resonance mechanism. Furthermore, a broadband super absorption higher than 0.8 in the entire 1.6μm–4μm region is achieved when VO2 film is patterned chessboard structure and transformed to metal phase beyond transition temperature. This broadband super absorption can be fulfilled in a wide range of incident angle (0°–70° and under all polarization conditions. Keywords: Phase change material, Metal-insulator-metal, Super absorption, Magnetic resonance

  8. Observation of reduced phase transition temperature in N-doped thermochromic film of monoclinic VO2

    Science.gov (United States)

    Wan, Meinan; Xiong, Mo; Li, Neng; Liu, Baoshun; Wang, Shuo; Ching, Wai-Yim; Zhao, Xiujian

    2017-07-01

    Research on monoclinic (M1) phase of VO2 has attracted a great of interest for smart coating applications due to its exceptional thermochromic property. Herein, we report the results using a novel approach to synthesize N-doped VO2(M1) thin films with high purity by heat treatment in NH3 atmosphere. The N dopant in the film can be regulated by varying NH3 concentration during the annealing process. We find that the N atoms are located at the interstitial sites or substitute oxygen atoms, and the V-N bonds in the VO2 thin films increase with NH3 concentration. The metal to insulator transition (MIT) temperature (τc,h) of the VO2 thin film is effectively reduced from 80.0 to 62.9 °C, while the solar modulation efficiency (ΔTsol) and the modulation efficiency at 2000 nm (ΔT2000nm) are 7.36% and 55.6% respectively. The band gap of N-doped VO2 thin films related to MIT (Eg1) is estimated to be as low as 0.18-0.25 eV whereas the band gap associated with the visible transparency (Eg2) is about 1.50-1.58 eV. Based on the highly accurate first-principles calculations, the Eg1 of VO2 (M1) is reduced after substituted or interstitial N-doping, while the Eg2 alters with the mode of N-doping, which is excellent agreement with experimental measurement.

  9. Development of a rowing-specific VO2max field test.

    Science.gov (United States)

    Huntsman, Heather D; DiPietro, Loretta; Drury, Daniel G; Miller, Todd A

    2011-06-01

    The purpose of this study was to develop an aerobic capacity test for rowers using minimal equipment that could be used in the field. Thirty rowers (15 men and 15 women) between the ages of 18 and 26 years were recruited on a volunteer basis from the District of Columbia metro area. The testing protocol consisted of a maximum of 7 2-minute stages on a rowing ergometer, separated by 30-second breaks where lactic acid concentrations were analyzed. Starting intensity for men was 200 W, although women started at 150 W, and each stage increased by 50 W. Expired gasses were collected during the test, and athletes were asked to row until maximal volition so that the directly measured VO2max could be compared to predicted values. Peak heart rates from each completed stage were plotted, and regression equations were calculated to predict VO2max. Separate regression equations were calculated for men and women. The predicted VO2max values were approximately 23 and 25% lower than what was actually achieved for men and women, respectively. Heart rate was a stronger correlate of VO2max in men compared with in women. Among men, we observed a moderate and statistically significant correlation (r = 0.55; p = 0.05), whereas among women, no such agreement was observed (r = -0.05; p > 0.85). The principle finding of this study was that the test was adequate in predicting VO2max in men but was inadequate in its prediction in women. With slight modifications to the testing protocol, stronger correlations and a more accurate prediction of VO2max is expected in men.

  10. Effect of high-intensity interval training on cardiovascular function, VO2max, and muscular force.

    Science.gov (United States)

    Astorino, Todd A; Allen, Ryan P; Roberson, Daniel W; Jurancich, Matt

    2012-01-01

    The purpose of this study was to examine the effects of short-term high-intensity interval training (HIIT) on cardiovascular function, cardiorespiratory fitness, and muscular force. Active, young (age and body fat = 25.3 ± 4.5 years and 14.3 ± 6.4%) men and women (N = 20) of a similar age, physical activity, and maximal oxygen uptake (VO2max) completed 6 sessions of HIIT consisting of repeated Wingate tests over a 2- to 3-week period. Subjects completed 4 Wingate tests on days 1 and 2, 5 on days 3 and 4, and 6 on days 5 and 6. A control group of 9 men and women (age and body fat = 22.8 ± 2.8 years and 15.2 ± 6.9%) completed all testing but did not perform HIIT. Changes in resting blood pressure (BP) and heart rate (HR), VO2max, body composition, oxygen (O2) pulse, peak, mean, and minimum power output, fatigue index, and voluntary force production of the knee flexors and extensors were examined pretraining and posttraining. Results showed significant (p VO2max, O2 pulse, and Wingate-derived power output with HIIT. The magnitude of improvement in VO2max was related to baseline VO2max (r = -0.44, p = 0.05) and fatigue index (r = 0.50, p 0.05) in resting BP, HR, or force production was revealed. Data show that HIIT significantly enhanced VO2max and O2 pulse and power output in active men and women.

  11. Relationship between Maximal Oxygen Consumption (VO2max) and Home Range Area in Mammals.

    Science.gov (United States)

    Albuquerque, Ralph L; Sanchez, Gabriela; Garland, Theodore

    2015-01-01

    Home range is defined as the area traversed during normal daily activities, such as foraging, avoiding predators, and social or antagonistic behaviors. All else being equal, larger home ranges should be associated with longer daily movement distances and/or higher average movement speeds. The maximal rate of oxygen consumption (VO2max) generally sets an upper limit to the intensity of work (e.g., speed of locomotion) that an animal can sustain without fatigue. Therefore, home range area and VO2max are predicted to evolve in concert (coadapt). We gathered literature data on home range and VO2max for 55 species of mammals. We computed residuals from log-log (allometric) regressions on body mass with two different regression models: ordinary least squares (OLS) and phylogenetic generalized least squares (PGLS). Residuals were weakly positively related for both the OLS (r = 0.278, one-tailed P 0.05) regressions. For VO2max, the PGLS regression model had a slightly higher likelihood than the OLS model, but the situation was reversed for home range area. In addition, for both home range area and VO2max, models that fit better than either OLS or PGLS were obtained by modeling residual variation with the Ornstein-Uhlenbeck process to mimic stabilizing selection (RegOU), indicating that phylogenetic signal is present in both size-adjusted traits, consistent with findings of previous studies. (However, residuals from the RegOU models cannot be tested for correlation due to mathematical complexities.) We conclude that the best estimate of the residual correlation is probably somewhere between these two values reported above. Possible reasons for the low correlation between residual home range area and VO2max are discussed.

  12. Influences of chemical sympathectomy, demedullation, and hindlimb suspension on the VO2max of rats

    Science.gov (United States)

    Woodman, C. R.; Stump, C. S.; Sebastian, L. A.; Tipton, C. M.

    1992-01-01

    Results from previous studies have shown that the reduction in maximal oxygen consumption (VO2max) with simulated microgravity is attenuated in chemically sympathectomized rats. To determine the contributions of the catecholamines from the adrenal medulla in this process, investigations were conducted with 65 saline injected (SAL) and chemically sympathectomized (SX) female rats that were either surgically demedullated (DM), or intact (IN). Microgravity conditions were simulated by head-down suspension (HDS) while controls were assigned to individual cages (CC). The experimental period was 14 d. The rats were tested for VO2max, treadmill run time (RT), and submaximal mechanical efficiency (ME) prior to suspension and on days 7 and 14. Saline injected rats that had intact adrenal medullas (SAL-IN) exhibited significantly reduced measures of VO2max after 7 and 14 d by 15% and 21%, respectively. No significant reduction in VO2max was observed with HDS in the SX-IN animals. Sympathectomized rats that were demedullated (SX-DM) also exhibited a significant reduction in VO2max (12%). In addition, HDS was associated with a marked and significant reduction in RT in all groups. ME for submaximal exercise was significantly reduced after HDS in SAL-IN rats but not in the SX-IN rats. SX-DM rats experienced significant reductions in ME similar in magnitude to the SAL-IN rats. These results confirm that chemical sympathectomy attenuates the expected decrease in VO2max with HDS and suggests that circulating epinephrine contributes to this response.

  13. MUSCLE FATIGUE INCREASES METABOLIC COSTS OF ERGOMETER CYCLING WITHOUT CHANGING VO2 SLOW COMPONENT

    Directory of Open Access Journals (Sweden)

    Aivaras Ratkevicius

    2006-09-01

    Full Text Available The aim of the present study was to investigate effects of muscle fatigue on oxygen costs of ergometer cycling and slow component of pulmonary oxygen uptake (VO2 kinetics. Seven young men performed 100 drop jumps (drop height of 40 cm with 20 s of rest after each jump. After the subsequent hour of rest, they cycled at 70, 105, 140 and 175 W, which corresponded to 29.6 ± 5.4, 39.4 ± 7.0, 50.8 ± 8.4 and 65.8 ± 11.8 % of VO2peak, respectively, for 6 min at each intensity with 4-min intervals of rest in between the exercise bouts. The VO2 response to cycling after the exercise (fatigue condition was compared to ergometer cycling without prior exercise (control condition. From 3rd to 6th min of cycling at 105, 140 and 175 W, VO2 was higher (p < 0.05-0.01 when cycling in the fatigue compared to the control condition. Slow component of VO2 kinetics was observed when cycling at 175 W in the control condition (0.17 ± 0.09, l·min-1, mean ± SD, but tended to decrease in the fatigue condition (0.13 ± 0.15 l·min-1. In summary, results of the study are in agreement with the hypothesis that muscle fatigue increases oxygen costs of cycling exercise, but does not affect significantly the slow component of pulmonary oxygen uptake (VO2 kinetics

  14. Estimated VO2max and its corresponding velocity predict performance of amateur runners

    Directory of Open Access Journals (Sweden)

    Bruno Ribeiro Ramalho Oliveira

    2012-03-01

    Full Text Available In recent years, there has been a substantial increase in the number of runners, with a proportional increase in their involvement in amateur street competition. Identification of the determinants of performance in this population appears necessary for optimization of time devoted to training. The objective of this study was to ascertain the association between estimated maximal oxygen uptake (VO2max, critical velocity (CV and VO2max velocity (VVO2max and athletic performance in the 3.6 km (uphill and 10 and 21.1 km (flatland events. Twelve amateur runners (nine male, mean age 36 ± 5 years underwent five tests: 1 and 5 km race on level ground, 3.6 km race with slope (≈8%, and indirect VO2max measurement. CV was determined from the linear relationship between distance and run time on the first two tests. The subjects then took part in two official 10 km and 21.1 km (half marathon races. VVO2max was calculated from the VO2max through a metabolic equation. VO2max showed the best association with running performance in the 10 and 21.1 km events. For the uphill race, VVO2max showed a better association. Overall, the variable with the highest average association was VO2max (0.91±0.07, followed by VVO2max (0.90±0.04 and VC (0.87±0.06. This study showed strong associations between physiological variables established by low-cost, user-friendly indirect methods and running performance in the 10 and 21.1 km (flatland and 3.6 km (uphill running events.

  15. Comparison of VO2max and disease risk factors between perimenopausal and postmenopausal women.

    Science.gov (United States)

    Lynch, Nicole A; Ryan, Alice S; Berman, Dora M; Sorkin, John D; Nicklas, Barbara J

    2002-01-01

    This study determines whether maximal oxygen consumption (VO2 max) is higher in perimenopausal women compared with similarly aged postmenopausal women and whether the lower VO2 max in postmenopausal women is associated with a higher total and visceral fat mass, less favorable lipid and glucose metabolism, and lower bone mineral density (BMD). Participants were 18 perimenopausal women (mean +/- SD; irregular menstrual cycle in the past 6 months) aged 49 +/- 4 years and 18 postmenopausal women (no menstrual cycle in the past year) aged 52 +/- 2 years who were matched for body mass index and race. Women were sedentary, and none were on hormone replacement therapy. Body composition (dual-energy x-ray absorptiometry and CT), VO2 max, fasting concentrations of sex steroid hormones, lipoproteins, insulin, and glucose were determined. VO2 max was 17% lower (22 +/- 3 v 27 +/- 7 mL.kg.min; P VO2 max (P < 0.05). Our data suggest that postmenopausal women have a lower VO2 max than perimenopausal women of a similar age and adiposity, which may be associated with an increased risk of total and central obesity and cardiovascular disease.

  16. Cardiopulmonary Exercise Testing in Patients with Chronic Heart Failure: Prognostic Comparison from Peak VO2 and VE/VCO2 Slope.

    Science.gov (United States)

    Sarullo, Filippo Maria; Fazio, Giovanni; Brusca, Ignazio; Fasullo, Sergio; Paterna, Salvatore; Licata, Pamela; Novo, Giuseppina; Novo, Salvatore; Di Pasquale, Pietro

    2010-05-26

    Cardiopulmonary exercise testing with ventilatory expired gas analysis (CPET) has proven to be a valuable tool for assessing patients with chronic heart failure (CHF). The maximal oxygen uptake (peak V02) is used in risk stratification of patients with CHF. The minute ventilation-carbon dioxide production relationship (VE/VCO2 slope) has recently demonstrated prognostic significance in patients with CHF. Between January 2006 and December 2007 we performed CPET in 184 pts (146 M, 38 F, mean age 59.8 +/- 12.9 years), with stable CHF (96 coronary artery disease, 88 dilated cardiomyopathy), in NYHA functional class II (n.107) - III (n.77), with left ventricular ejection fraction (LVEF) slope to predict cardiac related mortality and cardiac related hospitalization within 12 months after evaluation was examined. Peak VO2 and VE/VCO2 slope were demonstrated with univariate Cox regression analysis both to be significant predictor of cardiac-related mortality and hospitalization (p slope (41.80 +/- 8.07 vs. 29.84 +/- 6.47, p slope added additional value to VO2 peak as an independent prognostic factor (chi2: 56.48, relative risk: 1.08, 95% CI: 1.03 - 1.13, p = 0.001). The results from Kaplan-Meier analysis revealed a 1-year cardiac-related mortality of 75% in patients with VE/VCO2 slope >/= 35.6 and 25% in those with VE/VCO2 slope 12.2 ml/kg/min (log rank chi2: 50.98, p slope >/= 32.5 and 23% in those with VE/VCO2 slope 12.3 ml/kg/min (log rank chi2: 72.86, p slope was demonstrated with receiver operating characteristic curve analysis to be equivalent to peak VO2 in predicting cardiac-related mortality (0.89 vs. 0.89). Although area under the receiver operating characteristic curve for the VE/VCO2 slope was greater than peak VO2 in predicting cardiac-related hospitalization (0.88 vs 0.82), the difference was no statistically significant (p = 0.13). These results add to the present body of knowledge supporting the use of CPET in CHF patients. The VE/VCO2 slope, as an index of

  17. Time to exhaustion and time spent at a high percentage of VO2max in severe intensity domain in children and adults.

    Science.gov (United States)

    Leclair, Erwan; Mucci, Patrick; Borel, Benoit; Baquet, Georges; Carter, Helen; Berthoin, Serge

    2011-04-01

    The aim of the study was to compare time spent at a high percentage of VO2max (>90% of VO2max) (ts90%), time to achieve 90% of VO2max (ta90%), and time to exhaustion (TTE) for exercise in the severe intensity domain in children and adults. Fifteen prepubertal boys (10.3 ± 0.9 years) and 15 men (23.5 ± 3.6 years) performed a maximal graded exercise to determine VO2max, maximal aerobic power (MAP) and power at ventilatory threshold (PVTh). Then, they performed 4 constant load exercises in a random order at PVTh plus 50 and 75% of the difference between MAP and PVTh (PΔ50 and PΔ75) and 100 and 110% of MAP (P100 and P110). VO2max was continuously monitored. The P110 test was used to determine maximal accumulated oxygen deficit (MAOD). No significant difference was found in ta90% between children and adults. ts90% and TTE were not significantly different between children and adults for the exercises at PΔ50 and PΔ75. However, ts90% and TTE during P100 (p < 0.05 and p < 0.01, respectively) and P110 (p < 0.001) exercises were significantly shorter in children. Children had a significantly lower MAOD than adults (34.3 ± 9.4 ml · kg vs. 53.6 ± 11.1 ml · kg). A positive relationship (p < 0.05) was obtained between MAOD and TTE values during the P100 test in children. This study showed that only for intensities at, or higher than MAP, lower ts90% in children was linked to a reduced TTE, compared to adults. Shorter TTE in children can partly be explained by a lower anaerobic capacity (MAOD). These results give precious information about exercise intensity ranges that could be used in children's training sessions. Moreover, they highlight the implication of both aerobic and anaerobic processes in endurance performances in both populations.

  18. Cardiopulmonary Exercise Testing in Patients with Chronic Heart Failure: Prognostic Comparison from Peak VO2 and VE/VCO2 Slope

    Science.gov (United States)

    Sarullo, Filippo Maria; Fazio, Giovanni; Brusca, Ignazio; Fasullo, Sergio; Paterna, Salvatore; Licata, Pamela; Novo, Giuseppina; Novo, Salvatore; Di Pasquale, Pietro

    2010-01-01

    Background: Cardiopulmonary exercise testing with ventilatory expired gas analysis (CPET) has proven to be a valuable tool for assessing patients with chronic heart failure (CHF). The maximal oxygen uptake (peak V02) is used in risk stratification of patients with CHF. The minute ventilation-carbon dioxide production relationship (VE/VCO2 slope) has recently demonstrated prognostic significance in patients with CHF. Methods: Between January 2006 and December 2007 we performed CPET in 184 pts (146 M, 38 F, mean age 59.8 ± 12.9 years), with stable CHF (96 coronary artery disease, 88 dilated cardiomyopathy), in NYHA functional class II (n.107) - III (n.77), with left ventricular ejection fraction (LVEF) ≤ 45%,. The ability of peak VO2 and VE/VCO2 slope to predict cardiac related mortality and cardiac related hospitalization within 12 months after evaluation was examined. Results: Peak VO2 and VE/VCO2 slope were demonstrated with univariate Cox regression analysis both to be significant predictor of cardiac-related mortality and hospitalization (p 12.2 ml/kg/min (log rank χ2: 50.98, p 12.3 ml/kg/min (log rank χ2: 72.86, p < 0.0001). The VE/VCO2 slope was demonstrated with receiver operating characteristic curve analysis to be equivalent to peak VO2 in predicting cardiac-related mortality (0.89 vs. 0.89). Although area under the receiver operating characteristic curve for the VE/VCO2 slope was greater than peak VO2 in predicting cardiac-related hospitalization (0.88 vs 0.82), the difference was no statistically significant (p = 0.13). Conclusion: These results add to the present body of knowledge supporting the use of CPET in CHF patients. The VE/VCO2 slope, as an index of ventilatory response to exercise, is an excellent prognostic parameter and improves the risk stratification of CHF patients. It is easier to obtain than parameters of maximal exercise capacity and is of equivalent prognostic importance than peak VO2. PMID:20657715

  19. Near field thermal memory based on radiative phase bistability of VO2

    Science.gov (United States)

    Dyakov, S. A.; Dai, J.; Yan, M.; Qiu, M.

    2015-08-01

    We report the concept of a near-field memory device based on the radiative bistability effect in the system of two closely separated parallel plates of SiO2 and VO2 which exchange heat by thermal radiation in vacuum. We demonstrate that the VO2 plate, having metal-insulator transition at 340 K, has two thermodynamical steady-states. One can switch between the states using an external laser impulse. We show that due to near-field photon tunneling between the plates, the switching time is found to be only 5 ms which is several orders lower than in case of far field.

  20. Metal-insulator phase transition in a VO2 thin film observed with terahertz spectroscopy

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Fischer, Bernd M.; Thoman, Andreas

    2006-01-01

    We investigate the dielectric properties of a thin VO2 film in the terahertz frequency range in the vicinity of the semiconductor-metal phase transition. Phase-sensitive broadband spectroscopy in the frequency region below the phonon bands of VO2 gives insight into the conductive properties...... of the film during the phase transition. We compare our experimental data with models proposed for the evolution of the phase transition. The experimental data show that the phase transition occurs via the gradual growth of metallic domains in the film, and that the dielectric properties of the film...

  1. The characteristics of semiconductor-to-metal transition in VO2 of different morphology

    Science.gov (United States)

    Petukhova, Yu V.; Osmolowskaya, O. M.; Osmolowsky, M. G.

    2015-11-01

    Vanadium dioxide nanoparticles (NPs) of different morphologies were obtained using the hydrothermal technique. Their shape and size were studied by SEM, XRD and SSA estimation. The functional properties, structural changes and thermal behavior of samples obtained were investigated to clarify the SMPT peculiarities. It is shown that the introduction of a doping element changes a mechanism of the nanoparticles growth and so that the SMPT becomes less expressed. The detailed study of SMPT in undoped VO2 showed the steps of the transition process. The testing of VO2 coating on glass for «smart» windows was successfully performed.

  2. PENGEMBANGAN PERSAMAAN VO2 MAX DAN EVALUASI HR MAX (STUDI AWAL PADA PEKERJA PRIA

    Directory of Open Access Journals (Sweden)

    Purnawan Adi Wicaksono

    2012-10-01

    Full Text Available Kapasitas fisik maksimum seseorang direpresentasikan dengan nilai konsumsi oksigen maksimum (VO2 Max dan denyut nadi maksimum (HR Max yang memberikan suatu informasi batasan kemampuan fisik maksimum seseorang dalam melakukan pekerjaan. Penelitian kali ini mempunyai tujuan untuk mencari nilai VO2 Max pekerja pria Indonesia untuk nantinya akan dikembangkan suatu persamaan prediksi VO2 Max yang didekati dengan hubungan linier antara denyut nadi (Heart Rate seperti yang dilakukan Astrand (2003, tinggi badan (Chatterjee et al, 2006, berat badan (Akalan et al, 2008, usia (Magrani et al, 2009 dan mengevaluasi persamaan HR Max manakah yang dapat diaplikasikan untuk mendekati nilai denyut nadi maksimum pekerja Indonesia. Responden dalam penelitian kali ini adalah 12  pekerja industri pria yang diambil dari beberapa industri di Depok dan sekitarnya. Kriteria responden yang berpartisipasi dalam penelitian kali ini adalah: berusia 20-40 tahun, bukan perokok baik aktif maupun pasif, sehat , tidak mengkonsumsi makanan, kafein, alkohol minimal 2 jam sebelum eksperimen (Balderrama et. al, 2007.Eksperimen yang dilakukan menggunakan metode maximal test dengan protokol treadmill. Adapun peralatan yang digunakan adalah seperangkat alat pengukur kondisi fisiologi Fitmate MED (COSMED srl-Italy terdiri dari Heart Rate Transmitter, Heart Rate Receiver, V mask (Hans Rudolph Inc,dan treadmill SportArt@60.  Eksperimen dilakukan menjadi dua bagian, yaitu istirahat dan tahap bekerja.Aktivitas istirahat terdiri dari tidur selama 20 menit, duduk selama 20 menit dan berdiri selama 10 menit. Eksperimen tahap kedua yaitu tahap kerja yang terdiri dari latihan selama 5 menit. Responden dipersilakan beristirahat selama 15 menit, setelah itu responden melaksanakan maximal test detik hingga responden merasa tidak sanggup lagi melanjutkan eksperimen. Hasil penelitian model prediksi VO2 max untuk pekerja industri pria mempunyai nilai 2,78 ± 0,5 liter/menit dan dengan regresi linier

  3. RED-ML

    DEFF Research Database (Denmark)

    Xiong, Heng; Liu, Dongbing; Li, Qiye

    2017-01-01

    using diverse RNA-seq datasets, we have developed a software tool, RED-ML: RNA Editing Detection based on Machine learning (pronounced as "red ML"). The input to RED-ML can be as simple as a single BAM file, while it can also take advantage of matched genomic variant information when available...

  4. Prediction of VO2peak from the 20-m shuttle-run test in youth with Down syndrome.

    Science.gov (United States)

    Agiovlasitis, Stamatis; Pitetti, Kenneth H; Guerra, Myriam; Fernhall, Bo

    2011-04-01

    This study examined whether 20-m shuttle-run performance, sex, body mass index (BMI), age, height, and weight are associated with peak oxygen uptake (VO2peak) in youth with Down syndrome (DS; n = 53; 25 women, age 8-20 years) and whether these variables can be used to develop an equation to predict VO2peak. BMI, 20-m shuttle-run performance, and sex were significantly associated with VO2peak in youth with DS, whereas age, height, and weight were not. A regression model included only shuttle-run performance as a significant predictor of VO2peak; however, the developed prediction equation had low individual predictability. Therefore, 20-m shuttle-run performance alone does not provide valid prediction of VO2peak in youth with DS. Sex, BMI, age, height, and weight do not improve the prediction of VO2peak.

  5. Investigation on electrically-driven semiconductor-metal transition of polycrystalline VO2 thin films on two kinds of substrates

    Directory of Open Access Journals (Sweden)

    Deen Gu

    2018-01-01

    Full Text Available Electrical driving is one of frequently-used stimuli for the semiconductor-metal transition (SMT of VO2. But the driving mechanism is still under debate. We investigated the DC electrically-driven SMT features of polycrystalline VO2 thin films deposited on two kinds of substrates (quartz and silicon with obviously-different thermal conductivity and the influence of cooling by a thermo electric cooler (TEC on the SMT of VO2. Interestingly, the SMT doesn’t happen at a high voltage at very start, but at a relatively low one. Moreover, the SMT of VO2 thin films on silicon substrate is completely restrained by cooling through a TEC although the electric field strength across VO2 reaches 1.1×107 V/m. Our findings reveal that the Joule-heating effect plays an important role in the DC electrically-driven SMT of VO2.

  6. Pemberian minuman kombinasi maltodekstrin dan vitamin C terhadap mood negatif dan VO2 maks atlet sepak bola

    Directory of Open Access Journals (Sweden)

    Yuni Afriani

    2017-04-01

    Full Text Available Background: Stress during the match can influence the change of mood and performance of athletes. Physical exercise can improve the ability of physiologically and psychologically, but lead to fatigue, dehydration and hypoglycemia. Maltodextrin has a lower osmolarity to improve emotional and performance. Vitamin C as a cofactor of neurotransmitters can support the performance of athletes. Objective: This study aimed to determine the effectiveness of a combination drinks of maltodextrin and vitamin C on mood and the correlation with VO2 max of football athletes. Method: This research is a quasi experimental with same subject design. The subjects were 14 University state of Yogyakarta football athlete. Subjects received a drink of 15% maltodextrin and 250 mg of vitamin C in 300 ml given 30 minutes before and 5 minutes after the performance test using yo-yo intermittent test continued by physical exercise. Measurement of mood would be done in 3 times; before cardiorespiratory test, 5 minutes after physical exercise, and 15 minutes after drink. Results: There are significant changes after consuming a combination of maltodextrin and vitamin C on the confusion (p0.05. There are significant changes after consuming plain water on fatigue and tension (p0.05. There are no significant differences in every components of mood between two treatments. There is a correlation between anger and confusion with cardiorespiratory after consuming a combination of maltodextrin and vitamin C. Conclusion: Maltodextrin and vitamin C has the potential effect to improve the mood condition and have a correlation with VO2 Max improvement in football athletes.

  7. Hydrothermal route to VO2 (B) nanorods: controlled synthesis and characterization

    Science.gov (United States)

    Song, Shaokun; Huang, Qiwei; Zhu, Wanting

    2017-10-01

    One-dimensional vanadium dioxides have attracted intensive attention owing to their distinctive structure and novel applications in catalysis, high energy lithium-ion batteries, chemical sensors/actuators and electrochemical devices etc. In this paper, large-scale VO2 (B) nanorods have been successfully synthesized via a versatile and environment friendly hydrothermal strategy using V2O5 as vanadium source and carbohydrates/alcohols as reductant. The obtained samples are characterized by XRD, FT-IR, TEM, and XPS techniques to investigate the effects of chemical parameters such as reductants, temperature, and time of synthesis on the structure and morphology of products. Results show that pure B phase VO2 with homogeneous nanorod-like morphology can be prepared easily at 180 °C for 3 days with glycerol as reluctant. Typically, the nanorod-like products are 0.5-1 μm long and 50 nm width. Furthermore, it is also confirmed that the products are consisted of VO2, corresponding to the B phase. More importantly, this novel approach is efficient, free of any harmful solvents and surfactants. Therefore, this efficient, green, and cost-saving route will have great potential in the large-scale fabrication of 1D VO2 (B) nanorods from the economic and environmental point of view.

  8. Crystal Structure and Spectroscopic Properties of CsVO2SO4

    DEFF Research Database (Denmark)

    Rasmussen, Søren Birk; Boghosian, S.; Nielsen, Kurt

    2004-01-01

    in the range 1.725(1)-1.984(2) Angstrom. The deformation of the VO6 octahedron is thus much more pronounced compared to other known oxo sulfato V(V) compounds, and the coordination polyhedron of V(V) should be regarded as a tetragonal pyramid with the vanadium atom in the center. Each VO2+ group is coordinated...

  9. Nanoscale thermal imaging of VO2 via Poole-Frenkel conduction

    Science.gov (United States)

    Spitzig, Alyson; Hoffman, Jason D.; Pivonka, Adam E.; Mickalide, Harry; Frenzel, Alex; Kim, Jeehoon; Ko, Changhyun; Zhou, You; O'Connor, Kevin; Hudson, Eric W.; Ramanathan, Shriram; Hoffman, Jennifer E.

    We present a novel method for nanoscale thermal imaging of insulating thin films. We demonstrate this method on VO2, which undergoes a sharp insulator-to-metal transition at 340 K. We sweep the voltage applied to a conducting atomic force microscope tip in contact mode at room temperature and measure the resultant current through a VO2 film. The Poole-Frenkel (PF) conduction mechanism, which dominates in the insulating state of VO2, is fit to extract the local temperature of the film using fundamental constants and known film properties. We measure the local electric field and temperature immediately preceding the insulator-to-metal transition in VO2 to determine whether the transition can be triggered by an applied electric field alone. We calculate an average temperature of 334 +/- 5 K, implying that Joule heating has locally warmed the sample very close to the transition temperature. Our thermometry technique opens up the possibility to measure the local temperature of any film dominated by the PF conduction mechanism, and presents the opportunity to extend our technique to other conduction mechanisms. Canada Excellence Research Chair program and NSERC - CGSM.

  10. High contrast switchability of VO2 based metamaterial absorbers with ITO ground plane.

    Science.gov (United States)

    Pradhan, Jitendra K; Anantha Ramakrishna, S; Rajeswaran, Bharathi; Umarji, Arun M; Achanta, Venu Gopal; Agarwal, Amit K; Ghosh, Amitava

    2017-04-17

    A metamaterial consisting of an array of gold micro-disks, separated from a ground plane of indium tin oxide (ITO) by a thin film of vanadium dioxide (VO2), behaves as a perfect absorber at infrared (IR) frequencies at room temperature. This metamaterial, which is transparent to visible light, can be switched to a highly reflecting state for IR light by heating the metamaterial to temperatures larger than the metal-insulator phase transition temperature 68°C of VO2. For a disk diameter of 1.5 μm and VO2 film thickness of 320 nm, two absorption bands are obtained: one, that arises from the metamaterial resonance; and a second peak that arises principally from a Fabry-Pérot resonance. A large change (>78%) occurs in the reflectivity between the low and high temperature phases. IR emittance of the metamaterial was measured with IR cameras and shown to be switchable to result in low emittance at high temperature. Optical readout of the state of VO2 within the metamaterial is demonstrated.

  11. Ultrathin Films of VO2 on r-Cut Sapphire Achieved by Postdeposition Etching.

    Science.gov (United States)

    Yamin, Tony; Wissberg, Shai; Cohen, Hagai; Cohen-Taguri, Gili; Sharoni, Amos

    2016-06-15

    The metal-insulator transition (MIT) properties of correlated oxides thin films, such as VO2, are dramatically affected by strain induced at the interface with the substrate, which usually changes with deposition thickness. For VO2 grown on r-cut sapphire, there is a minimum deposition thickness required for a significant MIT to appear, around 60 nm. We show that in these thicker films an interface layer develops, which accompanies the relaxation of film strain and enhanced electronic transition. If these interface dislocations are stable at room temperature, we conjectured, a new route opens to control thickness of VO2 films by postdeposition thinning of relaxed films, overcoming the need for thickness-dependent strain-engineered substrates. This is possible only if thinning does not alter the films' electronic properties. We find that wet etching in a dilute NaOH solution can effectively thin the VO2 films, which continue to show a significant MIT, even when etched to 10 nm, for which directly deposited films show nearly no transition. The structural and chemical composition were not modified by the etching, but the grain size and film roughness were, which modified the hysteresis width and magnitude of the MIT resistance change.

  12. Influence of a physical exercise program on VO2max in adults with cardiovascular risk factors.

    Science.gov (United States)

    Meseguer Zafra, Marcos; García-Cantó, Eliseo; Rodríguez García, Pedro Luis; Pérez-Soto, Juan José; Tárraga López, Pedro Juan; Rosa Guillamón, Andrés; Tarraga López, M Loreto

    2018-01-29

    The aim of the study was to assess the influence of a physical exercise program on VO 2 max in sedentary subjects with cardiovascular risk factors. The sample was composed of 214 patients (80 males, 134 females) with an average age of 52 years, who were referred to a physical exercise program from 2 primary care centres of Spanish southeast. It was implemented a 10 week program (3 training×1h/week) combining strength with cardiorespiratory fitness. TheVO 2 max was analyzed through the Rockport Walk Test (RWT) comparing the pre and post program measurements. The results show significant improvements on VO 2 max for both genders (p<0,05). The most pronounced increase in VO 2 max was among males in the highest age band (56-73 years). Prescribing and referral exercise programs from primary care centers must be considered as a resource for improving cardiorespiratory fitness in the population studied. Copyright © 2017. Publicado por Elsevier España, S.L.U.

  13. Metal-Insulator Phase Transition in Quasi-One-Dimensional VO2 Structures

    Directory of Open Access Journals (Sweden)

    Woong-Ki Hong

    2015-01-01

    Full Text Available The metal-insulator transition (MIT in strongly correlated oxides has attracted considerable attention from both theoretical and experimental researchers. Among the strongly correlated oxides, vanadium dioxide (VO2 has been extensively studied in the last decade because of a sharp, reversible change in its optical, electrical, and magnetic properties at approximately 341 K, which would be possible and promising to develop functional devices with advanced technology by utilizing MITs. However, taking the step towards successful commercialization requires the comprehensive understanding of MIT mechanisms, enabling us to manipulate the nature of transitions. In this regard, recently, quasi-one-dimensional (quasi-1D VO2 structures have been intensively investigated due to their attractive geometry and unique physical properties to observe new aspects of transitions compared with their bulk counterparts. Thus, in this review, we will address recent research progress in the development of various approaches for the modification of MITs in quasi-1D VO2 structures. Furthermore, we will review recent studies on realizing novel functional devices based on quasi-1D VO2 structures for a wide range of applications, such as a gas sensor, a flexible strain sensor, an electrical switch, a thermal memory, and a nonvolatile electrical memory with multiple resistance.

  14. Gate-tunable gigantic changes in lattice parameters and optical properties in VO2

    Science.gov (United States)

    Nakano, Masaki; Okuyama, Daisuke; Shibuya, Keisuke; Ogawa, Naoki; Hatano, Takafumi; Kawasaki, Masashi; Arima, Taka-Hisa; Iwasa, Yoshihiro; Tokura, Yoshinori

    2014-03-01

    The field-effect transistor provides an electrical switching function of current flowing through a channel surface by external gate voltage (VG). We recently reported that an electric-double-layer transistor (EDLT) based on vanadium dioxide (VO2) enables electrical switching of the metal-insulator phase transition, where the low-temperature insulating state can be completely switched to the metallic state by application of VG. Here we demonstrate that VO2-EDLT enables electrical switching of lattice parameters and optical properties as well as electrical current. We performed in-situ x-ray diffraction and optical transmission spectroscopy measurements, and found that the c-axis length and the infrared transmittance of VO2 can be significantly modulated by more than 1% and 40%, respectively, by application of VG. We emphasize that these distinguished features originate from the electric-field induced bulk phase transition available with VO2-EDLT. This work was supported by the Japan Society for the Promotion of Science (JSPS) through its ``Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program).''

  15. Effects of Zirconium Ions Doping on the Structural and Thermochromic Properties of VO2 Thin Films

    Science.gov (United States)

    Li, Yuanbao; Liu, Juncheng; Wang, Danping; Dang, Yuanyuan

    2017-11-01

    As an inorganic functional material, VO2 thin films are expected to be used for smart windows. However, these films are not conducive to practical applications when the phase transition temperature ( Tc) of the VO2 is approximately 68°C, which is greater than room temperature. To decrease Tc, the effect of Zr4+ doping on the structure and properties of VO2 films were investigated. The films were prepared using a sol-gel process, spin-coating on quartz glasses, and annealing at 525°C in a tube furnace within a nitrogen atmosphere. The results demonstrate that these films have a highly preferential crystalline orientation on the substrate; however, the primary two x-ray diffraction pattern peaks shift slightly toward the small angle, and when 7 at.% Zr4+ was doped in the VO2 film, the deviation angle was 0.16°, and the crystallite size was approximately 98 nm. A large number of grains were found on the surface of the pure VO2 films, but all the Zr4+ doped films had a layered structure, and the thickness of the films was approximately 200 nm. The Tc of these films was characterized using differential scanning calorimetry, and the luminous and solar transmittance was characterized using a UV-Vis-NIR spectrophotometer, which demonstrated that the effect of Zr4+ doping decreased Tc by approximately 1°C per 1 at.% on average, and the Tc of the 7 at.% film was slightly greater than that of the 5 at.% film, the phase transition temperature of which was 61.4°C. The transmittance decreased as the doping concentration increased, and 1 at.% Zr4+ doping increased the luminous regulation efficiency (Δ T lum) and solar modulation efficiency (Δ T sol). The Δ T lum of the pure VO2 film and the 1 at.% Zr4+-doped VO2 films was 10.9% and 11.2%, and Δ T sol was 14.4 and 15.2%, respectively.

  16. qcML

    DEFF Research Database (Denmark)

    Walzer, Mathias; Pernas, Lucia Espona; Nasso, Sara

    2014-01-01

    provide tools for the calculation of a wide range of quality metrics as well as a database format and interconversion tools, so that existing LIMS systems can easily add relational storage of the quality control data to their existing schema. We here describe the qcML specification, along with possible......Quality control is increasingly recognized as a crucial aspect of mass spectrometry based proteomics. Several recent papers discuss relevant parameters for quality control and present applications to extract these from the instrumental raw data. What has been missing, however, is a standard data...... exchange format for reporting these performance metrics. We therefore developed the qcML format, an XML-based standard that follows the design principles of the related mzML, mzIdentML, mzQuantML and TraML standards from the HUPO-PSI (Proteomics Standards Initiative). In addition to the XML format, we also...

  17. Is Recreational Soccer Effective for Improving VO2max A Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Milanović, Zoran; Pantelić, Saša; Čović, Nedim; Sporiš, Goran; Krustrup, Peter

    2015-09-01

    Soccer is the most popular sport worldwide, with a long history and currently more than 500 million active participants, of whom 300 million are registered football club members. On the basis of scientific findings showing positive fitness and health effects of recreational soccer, FIFA (Fédération Internationale de Football Association) introduced the slogan "Playing football for 45 min twice a week-best prevention of non-communicable diseases" in 2010. The objective of this paper was to perform a systematic review and meta-analysis of the literature to determine the effects of recreational soccer on maximal oxygen uptake (VO2max). Six electronic databases (MEDLINE, PubMed, SPORTDiscus, Web of Science, CINAHL and Google Scholar) were searched for original research articles. A manual search was performed to cover the areas of recreational soccer, recreational physical activity, recreational small-sided games and VO2max using the following key terms, either singly or in combination: recreational small-sided games, recreational football, recreational soccer, street football, street soccer, effect, maximal oxygen uptake, peak oxygen uptake, cardiorespiratory fitness, VO2max. The inclusion criteria were divided into four sections: type of study, type of participants, type of interventions and type of outcome measures. Probabilistic magnitude-based inferences for meta-analysed effects were based on standardised thresholds for small, moderate and large changes (0.2, 0.6 and 1.2, respectively) derived from between-subject standard deviations for baseline fitness. Seventeen studies met the inclusion criteria and were included in the systematic review and meta-analysis. Mean differences showed that VO2max increased by 3.51 mL/kg/min (95 % CI 3.07-4.15) over a recreational soccer training programme in comparison with other training models. The meta-analysed effects of recreational soccer on VO2max compared with the controls of no exercise, continuous running and strength

  18. Earbud-based sensor for the assessment of energy expenditure, HR, and VO2max.

    Science.gov (United States)

    Leboeuf, Steven Francis; Aumer, Michael E; Kraus, William E; Johnson, Johanna L; Duscha, Brian

    2014-01-01

    The goal of this program was to determine the feasibility of a novel noninvasive, highly miniaturized optomechanical earbud sensor for accurately estimating total energy expenditure (TEE) and maximum oxygen consumption (VO2max). The optomechanical sensor module, small enough to fit inside commercial audio earbuds, was previously developed to provide a seamless way to measure blood flow information during daily life activities. The sensor module was configured to continuously measure physiological information via photoplethysmography and physical activity information via accelerometry. This information was digitized and sent to a microprocessor where digital signal-processing algorithms extract physiological metrics in real time. These metrics were streamed wirelessly from the earbud to a computer. In this study, 23 subjects of multiple physical habitus were divided into a training group of 14 subjects and a validation group of 9 subjects. Each subject underwent the same exercise measurement protocol consisting of treadmill-based cardiopulmonary exercise testing to reach VO2max. Benchmark sensors included a 12-lead ECG sensor for measuring HR, a calibrated treadmill for measuring distance and speed, and a gas-exchange analysis instrument for measuring TEE and VO2max. The earbud sensor was the device under test. Benchmark and device under test data collected from the 14-person training data set study were integrated into a preconceived statistical model for correlating benchmark data with earbud sensor data. Coefficients were optimized, and the optimized model was validated in the 9-person validation data set. It was observed that the earbud sensor estimated TEE and VO2max with mean ± SD percent estimation errors of -0.7 ± 7.4% and -3.2 ± 7.3%, respectively. The earbud sensor can accurately estimate TEE and VO2max during cardiopulmonary exercise testing.

  19. Earbud-Based Sensor for the Assessment of Energy Expenditure, Heart Rate, and VO2max

    Science.gov (United States)

    LeBoeuf, Steven F.; Aumer, Michael E.; Kraus, William E.; Johnson, Johanna L.; Duscha, Brian

    2014-01-01

    Introduction/Purpose The goal of this program was to determine the feasibility of a novel noninvasive, highly miniaturized optomechanical earbud sensor for accurately estimating total energy expenditure (TEE) and maximum oxygen consumption (VO2max). The optomechanical sensor module, small enough to fit inside commercial audio earbuds, was previously developed to provide a seamless way to measure blood flow information during daily life activities. The sensor module was configured to continuously measure physiological information via photoplethysmography (PPG) and physical activity information via accelerometry. This information was digitized and sent to a microprocessor where digital signal processing (DSP) algorithms extract physiological metrics in real-time. These metrics were streamed wirelessly from the earbud to a computer. Methods In this study, 23 subjects of multiple physical habitus were divided into a training group of 14 subjects and a validation group of 9 subjects. Each subject underwent the same exercise measurement protocol consisting of treadmill-based cardiopulmonary exercise (CPX) testing to reach VO2max. Benchmark sensors included a 12-lead electrocardiography (ECG) sensor for measuring heart rate, a calibrated treadmill for measuring distance and speed, and a gas-exchange analysis instrument for measuring TEE and VO2max. The earbud sensor was the device under test (DUT). Benchmark and DUT data collected from the 14-person training dataset study were integrated into a preconceived statistical model for correlating benchmark data with earbud sensor data. Coefficients were optimized, and the optimized model was validated in the 9-person validation dataset. Results It was observed that the earbud sensor estimated TEE and VO2max with mean ± SD percent estimation errors of −0.7 ± 7.4% and −3.2 ± 7.3% respectively. Conclusion The earbud sensor can accurately estimate TEE and VO2max during CPX testing. PMID:24743110

  20. Group training in adolescent runners: influence on VO2max and 5-km race performance.

    Science.gov (United States)

    Loprinzi, Paul D; Cardinal, Bradley J; Karp, Jason R; Brodowicz, Gary R

    2011-10-01

    The aims of this study were to (a) examine the interrelationships between training intensity, VO2max, and race performance in adolescent crosscountry runners and (b) determine if adolescent runners participating in a group crosscountry training program differ in the amount of training time at various intensities. In this study, 7 adolescent runners performed a laboratory-based VO2max test before and after a 9-week high-school crosscountry season. Heart rate (HR) and ventilatory threshold (VT) were used to identify 3 training zones for each runner based on the HR at ventilator threshold (HR(VT)): zone 1: >15 b·min(-1) below HR(VT); zone 2: between zone 1 and HR(VT); zone 3: >HR(VT). During each training session throughout the season, HR was measured to quantify the amount of training time in each of these 3 intensity zones. Results showed that the time in each of the 3 zones was not significantly associated with 5-km race performance. Zone 3 training time was positively associated with postseason VO2max (r = 0.73, p = 0.06); VO2max was significantly inversely associated with 5-km race performance (r = -0.77, p = 0.04). Each week, the amount of training time at, above, and below the VT was significantly different among the participants even though the training prescription for the group was standardized. The results suggest that, among adolescent crosscountry runners, training above the VT may be important in increasing VO2max and ultimately, race performance. Given the between-participant differences in the amount of training time in each HR zone, coaches should apply individual, rather than group, training programs.

  1. A new submaximal cycle ergometer test for prediction of VO2max.

    Science.gov (United States)

    Ekblom-Bak, E; Björkman, F; Hellenius, M-L; Ekblom, B

    2014-04-01

    Maximal oxygen uptake (VO2max) is an important, independent predictor of cardiovascular health and mortality. Despite this, it is rarely measured in clinical practice. The aim of this study was to create and evaluate a submaximal cycle ergometry test based on change in heart rate (HR) between a lower standard work rate and an individually chosen higher work rate. In a mixed population (n = 143) with regard to sex (55% women), age (21-65 years), and activity status (inactive to highly active), a model included change in HR per unit change in power, sex, and age for the best estimate of VO2max. The association between estimated and observed VO2max for the mixed sample was r = 0.91, standard error of estimate = 0.302 L/min, and mean measured VO2max = 3.23 L/min. The corresponding coefficient of variation was 9.3%, a significantly improved precision compared with one of the most commonly used submaximal exercise tests, the Åstrand test, which in the present study was estimated to be 18.1%. Test-retest reliability analysis over 1 week revealed no mean difference in the estimated VO2max (-0.02 L/min, 95% confidence interval: -0.07-0.03). The new test is low-risk, easily administered, and valid for a wide capacity range, and is therefore suitable in situations as health evaluations in the general population. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Graphene‐Nanowall‐Decorated Carbon Felt with Excellent Electrochemical Activity Toward VO2 +/VO2+ Couple for All Vanadium Redox Flow Battery

    Science.gov (United States)

    Li, Wenyue; Zhang, Zhenyu; Bian, Haidong; Ng, Tsz‐Wai

    2015-01-01

    3D graphene‐nanowall‐decorated carbon felts (CF) are synthesized via an in situ microwave plasma enhanced chemical vapor deposition method and used as positive electrode for vanadium redox flow battery (VRFB). The carbon fibers in CF are successfully wrapped by vertically grown graphene nanowalls, which not only increase the electrode specific area, but also expose a high density of sharp graphene edges with good catalytic activities to the vanadium ions. As a result, the VRFB with this novel electrode shows three times higher reaction rate toward VO2 +/VO2+ redox couple and 11% increased energy efficiency over VRFB with an unmodified CF electrode. Moreover, this designed architecture shows excellent stability in the battery operation. After 100 charging–discharging cycles, the electrode not only shows no observable morphology change, it can also be reused in another battery and practical with the same performance. It is believed that this novel structure including the synthesis procedure will provide a new developing direction for the VRFB electrode. PMID:27774399

  3. Graphene-Nanowall-Decorated Carbon Felt with Excellent Electrochemical Activity Toward VO2+/VO2+ Couple for All Vanadium Redox Flow Battery.

    Science.gov (United States)

    Li, Wenyue; Zhang, Zhenyu; Tang, Yongbing; Bian, Haidong; Ng, Tsz-Wai; Zhang, Wenjun; Lee, Chun-Sing

    2016-04-01

    3D graphene-nanowall-decorated carbon felts (CF) are synthesized via an in situ microwave plasma enhanced chemical vapor deposition method and used as positive electrode for vanadium redox flow battery (VRFB). The carbon fibers in CF are successfully wrapped by vertically grown graphene nanowalls, which not only increase the electrode specific area, but also expose a high density of sharp graphene edges with good catalytic activities to the vanadium ions. As a result, the VRFB with this novel electrode shows three times higher reaction rate toward VO2+/VO2+ redox couple and 11% increased energy efficiency over VRFB with an unmodified CF electrode. Moreover, this designed architecture shows excellent stability in the battery operation. After 100 charging-discharging cycles, the electrode not only shows no observable morphology change, it can also be reused in another battery and practical with the same performance. It is believed that this novel structure including the synthesis procedure will provide a new developing direction for the VRFB electrode.

  4. Lung function parameters improve prediction of VO2peak in an elderly population: The Generation 100 study.

    Directory of Open Access Journals (Sweden)

    Erlend Hassel

    Full Text Available Peak oxygen uptake (VO2peak is an indicator of cardiovascular health and a useful tool for risk stratification. Direct measurement of VO2peak is resource-demanding and may be contraindicated. There exist several non-exercise models to estimate VO2peak that utilize easily obtainable health parameters, but none of them includes lung function measures or hemoglobin concentrations. We aimed to test whether addition of these parameters could improve prediction of VO2peak compared to an established model that includes age, waist circumference, self-reported physical activity and resting heart rate. We included 1431 subjects aged 69-77 years that completed a laboratory test of VO2peak, spirometry, and a gas diffusion test. Prediction models for VO2peak were developed with multiple linear regression, and goodness of fit was evaluated. Forced expiratory volume in one second (FEV1, diffusing capacity of the lung for carbon monoxide and blood hemoglobin concentration significantly improved the ability of the established model to predict VO2peak. The explained variance of the model increased from 31% to 48% for men and from 32% to 38% for women (p<0.001. FEV1, diffusing capacity of the lungs for carbon monoxide and hemoglobin concentration substantially improved the accuracy of VO2peak prediction when added to an established model in an elderly population.

  5. Hydrothermal Synthesis of VO2 Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows.

    Science.gov (United States)

    Li, Ming; Magdassi, Shlomo; Gao, Yanfeng; Long, Yi

    2017-09-01

    Vanadium dioxide (VO2 ) is a widely studied inorganic phase change material, which has a reversible phase transition from semiconducting monoclinic to metallic rutile phase at a critical temperature of τc ≈ 68 °C. The abrupt decrease of infrared transmittance in the metallic phase makes VO2 a potential candidate for thermochromic energy efficient windows to cut down building energy consumption. However, there are three long-standing issues that hindered its application in energy efficient windows: high τc , low luminous transmittance (Tlum ), and undesirable solar modulation ability (ΔTsol ). Many approaches, including nano-thermochromism, porous films, biomimetic surface reconstruction, gridded structures, antireflective overcoatings, etc, have been proposed to tackle these issues. The first approach-nano-thermochromism-which is to integrate VO2 nanoparticles in a transparent matrix, outperforms the rest; while the thermochromic performance is determined by particle size, stoichiometry, and crystallinity. A hydrothermal method is the most common method to fabricate high-quality VO2 nanoparticles, and has its own advantages of large-scale synthesis and precise phase control of VO2 . This Review focuses on hydrothermal synthesis, physical properties of VO2 polymorphs, and their transformation to thermochromic VO2 (M), and discusses the advantages, challenges, and prospects of VO2 (M) in energy-efficient smart windows application. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Why is VO2 max after altitude acclimatization still reduced despite normalization of arterial O2 content?

    DEFF Research Database (Denmark)

    Calbet, J A L; Boushel, Robert Christopher; Radegran, G

    2003-01-01

    Acute hypoxia (AH) reduces maximal O2 consumption (VO2 max), but after acclimatization, and despite increases in both hemoglobin concentration and arterial O2 saturation that can normalize arterial O2 concentration ([O2]), VO2 max remains low. To determine why, seven lowlanders were studied at VO...

  7. Preparation and characterization of self-supporting thermochromic films composed of VO2(M)@SiO2 Nanofibers.

    Science.gov (United States)

    Li, Shaotang; Li, Yamei; Jiang, Meng; Ji, Shidong; Luo, Hongjie; Gao, Yanfeng; Jin, Ping

    2013-07-24

    Nanofibers of VO2(A) with the diameter and length averagely at 100 nm and 10-20 μm were prepared via a facile one-step hydrothermal method by reducing NH4VO3 with 1,3-propylene glycol in an acidic solution. The obtained VO2(A) was coated by SiO2 to form VO2(A)@SiO2 core-shell nanocomposites, which were then transformed into VO2(M)@SiO2 by annealing under nitrogen atmosphere. The resulted composites maintained the original fibrous morphology, particularly with a large amount of pores emerging inside the fiber due to the volume shrinkage during the phase transition, which may improve its thermal insulation ability in real applications. The VO2(M)@SiO2 nanofibers were arranged into a self-supporting film by filtration, which shows excellent thermochromic properties.

  8. Hydrogen-doping induced reduction in the phase transition temperature of VO2: a first-principles study.

    Science.gov (United States)

    Cui, Yuanyuan; Shi, Siqi; Chen, Lanli; Luo, Hongjie; Gao, Yanfeng

    2015-08-28

    VO2 is a promising thermochromic material that can intelligently control the transmittance of sunlight in the near-infrared region in response to temperature change, although the high phase transition temperature (Tc) of 340 K restricts its wide application. Our first-principles calculations show that hydrogen is an efficient dopant which can stabilize the metallic VO2 phase at ambient temperature through reducing Tc by 38 K/at% H. The reduction in Tc is coupled with the changes in atomic and electronic structures, i.e., the V-V chains feature the dimerization characteristics in H-doped VO2(R) and the V-O bonds become less ionic due to the formation of a typical H-O covalent bond. In addition, hydrogen-doped VO2 is more sensitive to external strain as compared with pure VO2, implying that Tc can be further regulated through a combination of H-doping and strain.

  9. Avalanche breakdown and self-stabilization effects in electrically driven transition of carbon nanotube covered VO2 film

    Science.gov (United States)

    Chen, Yuliang; Chen, Shi; Liu, Qianghu; Ren, Hui; Zheng, Xusheng; Wang, Liangxin; Lu, Yuan; Song, Li; Zhang, Guobin; Zou, Chongwen

    2017-06-01

    Electrical-driven metal-insulator transition (MIT) is quite vital and widespread for both applications and MIT mechanism of VO2. In this report, we discussed the avalanche breakdown and self-stabilization effects behind the electrically driven phase transition in macro-scale carbon nanotube covered VO2 film to further understand the phase transition behaviors as well as explore promising electrical-driven VO2 devices. It was found that the Joule heat was the main source to trigger the phase transition of VO2 film. However, the time-dependent triggering routes were quite different, since the avalanche behavior was observed under the voltage-driven mode, while the gradual self-stabilization existed in the current-driven mode. The simulation results based on the proposed thermodynamics models were in good agreement with the experimental phenomena, which were basically originated from the intrinsic first-order phase transition properties of VO2 film.

  10. Criterion related validity of 1/2 mile run-walk test for estimating VO2peak in children aged 6-17 years.

    Science.gov (United States)

    Castro-Piñero, J; Ortega, F B; Mora, J; Sjöström, M; Ruiz, J R

    2009-05-01

    We assessed the criterion related validity of 1/2 mile run/walk (1/2MRW) test for estimating VO2peak in children aged 6-17 years. The criterion related validity of the Fernhall's equation in a sub-group of children aged 10-17 years was also examined. A total of 86 children completed a maximal graded treadmill test and the 1/2MRW test. The cohort was randomly divided into either validation (n=47) or a cross-validation (n=39) group. A regression equation was computed and assessed through several error measures, and the Bland and Altman method. There was no systematic bias in the validation group nor in the cross-validation group (P > 0.1). The root mean sum of squared errors (RMSE), and the percentage error were 6.5 ml/kg/min, and 13.9%, respectively. These figures were very similar in the cross-validation group. The new equation had a lower RMSE and percentage error than the Fernhall's Equation (6.2 vs. 19.7 ml/kg/min, and 16% vs. 50.4%, respectively, Pvalid for estimating VO2peak from the 1/2MRW time, sex, and body mass index in healthy children aged 6-17 years, and is more accurate than Fernhall's equation in the sample studied.

  11. Slow VO2 off-kinetics in skeletal muscle is associated with fast PCr off-kinetics--and inversely.

    Science.gov (United States)

    Korzeniewski, Bernard; Zoladz, Jerzy A

    2013-09-01

    The computer model of the bioenergetic system in skeletal muscle, developed previously, was used to study the effect of the characteristic decay time of the parallel activation of oxidative phosphorylation [τ(OFF)] during muscle recovery on the muscle oxygen consumption rate (Vo2) and phosphocreatine (PCr) work-to-rest transition (off)-kinetics and on the relationship between the Vo2 and PCr rest-to-work transition (on)- and off-kinetics in moderate and heavy exercise. An increase in τ(OFF) slows down the initial phase of the muscle Vo2 off-kinetics and accelerates the PCr off-kinetics. As a result, the relationship between the initial phase of the Vo2 off-kinetics (lasting approximately 3-60 s in computer simulations) and the PCr off-kinetics is inverse: the slower the former, the faster the latter. A faster initial phase of the Vo2 off-kinetics is associated with a slower late phase of the Vo2 off-kinetics, and as a result, the integral of Vo2 above baseline during recovery, representing the oxygen debt, is identical in all cases [values of τ(OFF)] for a given PCr decrease. Depending on τ(OFF), the muscle Vo2 on-kinetics was either equally fast or slower than the Vo2 off-kinetics in moderate exercise and always slower in heavy exercise. PCr on-kinetics was always faster than PCr off-kinetics. This study clearly demonstrates that τ(OFF) has a pronounced impact on the mutual relations between the muscle Vo2 and PCr on- and off-kinetics.

  12. The 1-mile walk test is a valid predictor of VO(2max) and is a reliable alternative fitness test to the 1.5-mile run in U.S. Air Force males.

    Science.gov (United States)

    Weiglein, Laura; Herrick, Jeffery; Kirk, Stacie; Kirk, Erik P

    2011-06-01

    The purpose of this study was to assess the validity of the 1-mile walk (Rockport Walk Test) as a predictor of VO(2max) and determine whether the 1-mile walk is a reliable alternative to the 1.5-mile run in moderately fit to highly fit U.S. Air Force males. Twenty-four (33.0 +/- 1.5 years) males completed a maximal treadmill VO(2max) (50.3 +/- 1.4 mL/ kg/min), 1-mile walk, and 1.5-mile run. For the 1-mile walk, there were no significant differences between measured and predicted VO(2max) (p = 0.177, r = 0.817). There were no significant differences (p = 0.573) between points scored in the Air Force Fitness Test for the 1-mile walk and 1.5-mile run tests. In conclusion, the 1-mile walk test is a valid predictor of VO(2max) and can be used as an alternative fitness test to the 1.5-mile run in assessing cardiovascular fitness in Air Force males.

  13. Estimating VO2max in children aged 5-6 years through the preschool-adapted 20-m shuttle-run test (PREFIT).

    Science.gov (United States)

    Mora-Gonzalez, Jose; Cadenas-Sanchez, Cristina; Martinez-Tellez, Borja; Sanchez-Delgado, Guillermo; Ruiz, Jonatan R; Léger, Luc; Ortega, Francisco B

    2017-11-01

    (1) To examine the comparability, i.e., discriminatory power, in a preschooler test (PREFIT 20-m shuttle-run test) and the 20mSRT-Original in 5-6-year-olds; (2) to provide an equation to estimate VO2max from the 20mSRT-PREFIT. 138 participants aged 5-6 years performed the 20mSRT-PREFIT and the 20mSRT-Original in a counterbalanced order. Total test duration, completed stages, maximum speed and maximum heart rate were registered. Participants finished stages from 2-10 in the 20mSRT-PREFIT, whereas stages 1-5 were completed in the 20mSRT-Original and a null was registered, showing the original version a lower discriminatory power. We also observed that the higher the cardiorespiratory fitness level the more comparable were the tests, i.e., - 0.04 km h-1 difference between tests in the fittest participants (i.e., maximum speed ≥ 9.5 km h-1). Using the original equation proposed by Leger and colleagues in 1988 and based on the estimation regression of maximum speed in the 20mSRT-Original from the PREFIT version, we computed a new equation to estimate VO2max from the 20mSRT-PREFIT: Y = 44.657 + 1.795X 1   - 2.601X 2  + 0.0852X 1 X 2 (r = 0.77; r 2 = 0.59; SEE = 1.25 ml kg-1 min-1 or 2.59% of estimated mean VO2max = 48.38 ml kg-1 min-1), where X 1 is the 20mSRT-PREFIT maximum speed (km h-1) and X 2 is the age of participants. The 20mSRT-PREFIT resulted in a significantly higher maximum heart rate than the 20mSRT-Original. The 20mSRT-PREFIT has higher discriminatory power than the 20mSRT-Original. Our study provides for the first time an opportunity to estimate VO2max in preschoolers and children based on the 20mSRT-PREFIT maximum speed and the age of participants.

  14. VO2 kinetics and performance in soccer players after intense training and inactivity

    DEFF Research Database (Denmark)

    Christensen, Peter Møller; Krustrup, Peter; Gunnarsson, Thomas P.

    2011-01-01

    PURPOSE:: To examine the effects of a short-term period with intensified training or training cessation of trained soccer players on VO2 kinetics at 75% maximal aerobic speed (MAS), oxidative enzymes and performance in repeated high intensity exercise. METHODS:: After the last match of the season...... 18 elite soccer players were, for a two-week period, assigned to a high intensity training group (HI, n=7) performing 10 training sessions mainly consisting of aerobic high intensity training (8×2 min) and speed endurance training (10-12×30-s sprints) or a training cessation group (TC, n=11......) that refrained from training. RESULTS:: For TC, VO2 kinetics became slower (P...

  15. Mesoscopic Metal-Insulator Transition at Ferroelastic Domain Walls in VO2

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Keith M [ORNL; Kalinin, Sergei V [ORNL; Kolmakov, Andrei [ORNL; Luk' yanchuk, Prof. Igor A. [University of Picardie Jules Verne, Amiens, France; Meunier, Vincent [ORNL; Proksch, Roger [Asylum Research, Santa Barbara, CA; Shelton Jr, William Allison [ORNL; Strelcov, Evgheni [Southern Illinois University; Tselev, Alexander [ORNL

    2010-01-01

    The novel phenomena induced by symmetry breaking at homointerfaces between ferroic variants in ferroelectric and ferroelastic materials have attracted recently much attention. Using variable temperature scanning microwave microscopy, we demonstrate the mesoscopic strain-induced metal-insulator phase transitions in the vicinity of ferroelastic domain walls in the semiconductive VO2 that nucleated at temperatures as much as 10-12 C below bulk transition, resulting in the formation of conductive channels in the material. Density functional theory is used to rationalize the process low activation energy. This behavior, linked to the strain inhomogeneity inherent in ferroelastic materials, can strongly affect interpretation of phase-transition studies in VO2 and similar materials with symmetry-lowering transitions, and can also be used to enable new generations of electronic devices though strain engineering of conductive and semiconductive regions.

  16. Evidence of a pressure-induced metallization process in monoclinic VO2.

    Science.gov (United States)

    Arcangeletti, E; Baldassarre, L; Di Castro, D; Lupi, S; Malavasi, L; Marini, C; Perucchi, A; Postorino, P

    2007-05-11

    Raman and combined infrared transmission and reflectivity measurements were carried out at room temperature (RT) on monoclinic VO2 over the 0-19 GPa and 0-14 GPa pressure ranges. Both lattice dynamics and optical gap show a remarkable stability up to P* approximately 10 GPa whereas subtle modifications of V ion arrangements within the monoclinic lattice, together with the onset of a metallization process via band gap filling, are observed for P >P*. Differently from P=0, where the VO2 metallic phase is found only in conjunction with the rutile structure above 340 K, a new RT metallic phase within a monoclinic structure appears accessible in the high pressure regime.

  17. EPR and optical absorption studies on VO 2+ ions in calcium fumarate trihydrate single crystals

    Science.gov (United States)

    Kripal, Ram; Mishra, Indrajeet; Gupta, S. K.; Arora, Manju

    2010-01-01

    Electron Paramagnetic Resonance (EPR) studies of VO 2+ ions in calcium fumarate trihydrate single crystals have been done at room temperature. EPR analysis indicates the presence of two magnetically inequivalent VO 2+ sites. For the two sites the spin Hamiltonian parameters are, Site I: g x = 1.9689 ,g y = 2.0087 ,g z = 1.9344, A x = 73 ,A y = 88 ,A z = 202; Site II: g x = 1.9675 ,g y = 2.0100 ,g z = 1.9346 ,A x = 75 ,A y = 90, A z = 206 (×10 -4) cm -1. The optical absorption study is also carried out at room temperature. By correlating EPR and optical data the nature of bonding in the crystal is discussed. The three-line superhyperfine structure has been attributed to two protons.

  18. Comparison of V'O2 kinetics in upright and supine position

    Science.gov (United States)

    Hoffmann, U.; Eßfeld, D.; Stegemann, J.; Schütze, H.

    Oxygen uptake (V'O2) kinetics during exercise depends in particular on muscular aerobic capacity and cardio-vascular parameters. The objective of this study was to investigate the influence of body position on the V'O2 kinetics as determined by means of the PRBS technique. 9 healthy male volunteers performed bicycle ergometer exercise in both upright and supine position. No significant changes were seen in normalized gains and phase shifts of the power-V'O2-relationship. It is concluded that the differences in venous blood volume distribution and cardiac output associated with upright and supine position do not have major effects on power-V'O2-gains.

  19. The highest velocity and the shortest duration permitting attainment of VO2max during running

    Directory of Open Access Journals (Sweden)

    Tiago Turnes

    2015-02-01

    Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n2p226   The severe-intensity domain has important applications for the prescription of running training and the elaboration of experimental designs. The objectives of this study were: 1 to investigate the validity of a previously proposed model to estimate the shortest exercise duration (TLOW and the highest velocity (VHIGH at which VO2max is reached during running, and 2 to evaluate the effects of aerobic training status on these variables. Eight runners and eight physically active subjects performed several treadmill running exercise tests to fatigue in order to mathematically estimate and to experimentally determine TLOW and VHIGH. The relationship between the time to achieve VO2max and time to exhaustion (Tlim was used to estimate TLOW. VHIGH was estimated using the critical velocity model. VHIGH was assumed to be the highest velocity at which VO2 was equal to or higher than the average VO2max minus one standard deviation. TLOW was defined as Tlim associated with VHIGH. Runners presented better aerobic fitness and higher VHIGH (22.2 ± 1.9 km.h-1 than active subjects (20.0 ± 2.1 km.h-1. However, TLOW did not differ between groups (runners: 101 ± 39 s; active subjects: 100 ± 35 s. TLOW and VHIGH were not well estimated by the model proposed, with high coefficients of variation (> 6% and a low correlation coefficient (r<0.70, a fact reducing the validity of the model. It was concluded that aerobic training status positively affected only VHIGH. Furthermore, the model proposed presented low validity to estimate the upper boundary of the severe-intensity domain (i.e., VHIGH, irrespective of the subjects’ training status.

  20. Increased hemoglobin mass and VO2max with 10 h nightly simulated altitude at 3000 m.

    Science.gov (United States)

    Neya, Mitsuo; Enoki, Taisuke; Ohiwa, Nao; Kawahara, Takashi; Gore, Christopher J

    2013-07-01

    To quantify the changes of hemoglobin mass (Hbmass) and maximum oxygen consumption (VO2max) after 22 days training at 1300-1800 m combined with nightly exposure to 3000-m simulated altitude. We hypothesized that with simulated 3000-m altitude, an adequate beneficial dose could be as little as 10 h/24 h. Fourteen male collegiate runners were equally divided into 2 groups: altitude (ALT) and control (CON). Both groups spent 22 days at 1300-1800 m. ALT spent 10 h/night for 21 nights in simulated altitude (3000 m), and CON stayed at 1300 m. VO2max and Hbmass were measured twice before and once after the intervention. Blood was collected for assessment of percent reticulocytes (%retics), serum erythropoietin (EPO), ferritin, and soluble transferrin receptor (sTfR) concentrations. Compared with CON there was an almost certain increase in absolute VO2max (8.6%, 90% confidence interval 4.8-12.6%) and a likely increase in absolute Hbmass (3.5%; 0.9-6.2%) at postintervention. The %retics were at least very likely higher in ALT than in CON throughout the 21 nights, and sTfR was also very likely higher in the ALT group until day 17. EPO of ALT was likely higher than that of CON on days 1 and 5 at altitude, whereas serum ferritin was likely lower in ALT than CON for most of the intervention. Together the combination of the natural and simulated altitude was a sufficient total dose of hypoxia to increase both Hbmass and VO2max.

  1. Effects of a new experimental training program on V.O2max and running performance.

    Science.gov (United States)

    Sporis, G; Ruzic, L; Leko, G

    2008-06-01

    By testing the V.O(2max) and running performance in soccer players, the purpose of the study was to determine whether an experimental conditioning program would elicit better effects than the widely used traditional program, especially across longer distances. Laboratory measurements of maximal oxygen consumption and maximal heart rate were performed on 48 soccer players (U19) from two first league soccer teams (Experimental team, n=24; Control team n=24). Exercise intensities were calculated from heart rate maximum. Detailed training programs for both the experimental and control groups were designed for the 13-week period. The main intervention was performed in the conditioning phase where the control group performed traditional conditioning (straight-line running, with stretching exercises in the break) and the experimental group underwent a conditioning training program on designed polygon, very much akin to a real game situation; sprint-runs with or without the ball and rapid changes in direction. During the 20, 40 or 60m sprint-run the players had to perform specific ball drills depending on marked polygon station. Running performance at 60, 100, 200, 400, 800, 1200, 2 400 m distances and V.O(2max) were tested in the initial, transitory (week 6) and final trials. Significant improvement in 200, 400, 800, 1200, 2 400 m running performance and V.O(2max) (Ptrial. However, in this group the gained improvements quickly disappeared after the beginning of the competitive season as recorded at the final trial. Discriminant analysis revealed that the groups differed the most in the 200 m variable. The new experimental program is better suited for the enhancement of V.O(2max) and running performance in soccer players and the gained improvement lasted well into the competition season.

  2. Identifying the Collective Length in VO2 Metal-Insulator Transitions.

    Science.gov (United States)

    Yajima, Takeaki; Nishimura, Tomonori; Toriumi, Akira

    2017-03-01

    The "collective length" in VO2 metal-insulator transitions is identified by controlling nanoscale dopant distribution in thin films. The crossover from the local transition to the collective transition is observed, which originates from the increased instability of the metal-insulator domain boundary. This instability renders the transition collective within the "collective length", which will enable the design of collective electronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Effects of concurrent training on explosive strength and VO(2max) in prepubescent children.

    Science.gov (United States)

    Marta, C; Marinho, D A; Barbosa, T M; Izquierdo, M; Marques, M C

    2013-10-01

    The purpose of this study was to compare the effects of an 8-weeks training period of resistance training alone (GR), combined resistance and endurance training (GCON) and a control group (GC) on explosive strength and V(O2max) in a large sample of prepubescent boys and girls. 125 healthy children (58 boys, 67 girls), aged 10-11 years old (10.8±0.4 years) were assigned into 2 training groups to train twice a week for 8 weeks: GR (19 boys, 22 girls), GCON (21 boys, 24 girls) and a control group (GC: 18 boys, 21 girls; no training program). A significant but medium-sized increase from pre- to the post-training in the vertical jump (Effect size=0.22, F=34.44, ptraining group (GR and GCON) and sex factors did not significantly influence the evolution of strength variables from pre- to the post-training. The V(O2max) increased significantly only in GCON. Concurrent training is equally effective on training-induced explosive strength, and more efficient than resistance training only for V(O2max), in prepubescent boys and girls. This should be taken into consideration in order to optimize strength training school-based programs. © Georg Thieme Verlag KG Stuttgart · New York.

  4. VO2max Measured with a Self-selected Work Rate Protocol on an Automated Treadmill.

    Science.gov (United States)

    Scheadler, Cory M; Devor, Steven T

    2015-10-01

    The use of graded maximal exercise tests for measuring maximal oxygen consumption (VO2max) is common practice in both cardiopulmonary rehabilitation settings and in sports medicine research. Recent alterations of common testing protocols to allow for self-selected work rates (SPV) have elicited V˙O2max values similar to or higher than more traditional style protocols (TP). Research is lacking in the delivery of the SPV protocol using a treadmill modality. The purpose of the study was to examine the validity of an SPV using an automated treadmill for measuring cardiorespiratory fitness. Thirteen experienced endurance runners completed three maximal exercise tests on a treadmill. Oxygen consumption was measured using a computerized system and averaged more than 30-s time periods. SPV was completed using an automated treadmill that consisted of a sonar range finder, microcontroller, and customized computer software. Subject deviations from the middle of the treadmill belt resulted in rapid, graded increases or decreases in speed. TP was completed on the same treadmill without the use of the automated software. A verification phase protocol (VP) was used to verify if VO2 was maximal. Peak work rate achieved during SPV was significantly greater than that achieved during TP by 1.2 METs; P VO2max than TP despite higher work rates.

  5. Roles of strain and domain boundaries on the phase transition stability of VO2 thin films

    Science.gov (United States)

    Jian, Jie; Chen, Aiping; Chen, Youxing; Zhang, Xinghang; Wang, Haiyan

    2017-10-01

    The fundamental phase transition mechanism and the stability of the semiconductor-to-metal phase transition properties during multiple thermal cycles have been investigated on epitaxial vanadium dioxide (VO2) thin films via both ex situ heating and in situ heating by transmission electron microscopy (TEM). VO2 thin films were deposited on c-cut sapphire substrates by pulsed laser deposition. Ex situ studies show the broadening of transition sharpness (ΔT) and the width of thermal hysteresis (ΔH) after 60 cycles. In situ TEM heating studies reveal that during thermal cycles, large strain was accumulated around the domain boundaries, which was correlated with the phase transition induced lattice constant change and the thermal expansion. It suggests that the degradation of domain boundary structures in the VO2 films not only caused the transition property reduction (e.g., the decrease in ΔT and ΔH) but also played an important role in preventing the film from fracture during thermal cycles.

  6. Characterization of pulsed laser deposition grown V2O3 converted VO2

    Science.gov (United States)

    Majid, Suhail; Shukla, D. K.; Rahman, F.; Gautam, Kamini; Sathe, V. G.; Choudhary, R. J.; Phase, D. M.

    2016-10-01

    Controllable tuning of Metal-insulator transition in VxOy thin film has been a field of extensive research. However controlled synthesis of desired Vanadium oxide phase is a challenging task. We have successfully achieved VO2 phase on Silicon substrate after post deposition annealing treatment to the PLD grown as deposited V2O3 thin films. The annealed thin film was characterized by x-ray diffraction (XRD), resistivity, Raman spectroscopy, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) measurements. XRD confirms the crystalline nature and growth of VO2 phase in thin film. The characteristic MIT was observed from resistivity measurements and transition temperature appeared at lower value around 336 K, compared to bulk VO2. The structural transition accompanied with MIT from lower temperature monoclinic phase to higher temperature Rutile phase became evident from temperature dependent Raman measurements. Chemical state of vanadium was examined using XAS and XPS measurements which confirm the presence of +4 oxidation state of vanadium in thin film.

  7. Central and peripheral cardiovascular impairments limit VO(2peak) in type 1 diabetes.

    Science.gov (United States)

    Rissanen, Antti-Pekka E; Tikkanen, Heikki O; Koponen, Anne S; Aho, Jyrki M; Peltonen, Juha E

    2015-02-01

    Cardiovascular risk, predicted by peak O2 uptake (VO(2peak)), is increased in type 1 diabetes. We examined the contribution of central and peripheral mechanisms to VO(2peak) in physically active adults with type 1 diabetes. Seven men with type 1 diabetes and 10 healthy age-, anthropometry-, and physical activity-matched men performed incremental cycling exercise until volitional fatigue. Alveolar gas exchange (turbine and mass spectrometry), cardiac function and systemic vascular resistance (impedance cardiography), and local active leg muscle deoxygenation and blood flow (near infrared spectroscopy) were monitored. Arterial-venous O2 difference was calculated (Fick principle). Blood volume (BV) (carbon monoxide rebreathing method) and glycemic control (glycosylated hemoglobin) were determined. The group with diabetes had lower VO(2peak) than controls (47 ± 5 vs 56 ± 7 mL·min·kg fat-free mass, P systemic vascular resistance was higher in the group with diabetes than those in controls (P 0.05). The group with diabetes had lower relative BV than controls (P control.

  8. EVALUATION AND COMPARISON OF VO2MAX ASSESSMENT MODELS IN HIGH SCHOOL STUDENTS

    Directory of Open Access Journals (Sweden)

    Lotfali Bolboli

    2013-02-01

    Full Text Available The purpose of this study was to evaluation and comparison of VO2max assessment models in students. Thirty students from high schools of Ardabil city were selected randomly and served as subjects in this study (age: 15.73±0.69 year, height: 169.46±8.1 cm, weight: 61.70±9.32 kg. Subjects were divided into two groups. In one group Rockport test was used to estimate their VO2 max and in other group Balk test was used for the same purpose. Also, the VO2max of both groups were examined by a standard treadmill test and the results were compared with the results of field tests. The one way of ANOVA and Tukey's post-hoc tests were used for data analysis (p>0/05. The results showed that there were significant differences between the results of the field tests and standard treadmill test (Bruce: 40.93±5.83 vs. Rockport: 58.71±2.73 and Balke: 52.09± 6.18. As a result of these findings it was concluded that the regression equations used in this study used is not suitable for 15-17 (yr boys and does not estimate their aerobic power correctly.

  9. Peak VO2 and VE/VCO2 slope in patients with heart failure: a prognostic comparison.

    Science.gov (United States)

    Arena, Ross; Myers, Jonathan; Aslam, Syed Salman; Varughese, Elsa B; Peberdy, Mary Ann

    2004-02-01

    Exercise testing with ventilatory expired gas analysis has proven to be a valuable tool for assessing patients with heart failure (HF). Peak oxygen consumption (peak VO2) continues to be considered the gold standard for assessing prognosis in HF. The minute ventilation--carbon dioxide production relationship (VE/VCO2 slope) has recently demonstrated prognostic significance in patients with HF, and in some studies, it has outperformed peak VO2. Two hundred thirteen subjects, in whom HF was diagnosed, underwent exercise testing between April 1, 1993, and October 19, 2001. The ability of peak VO2 and VE/VCO2 slope to predict cardiac-related mortality and hospitalization was examined. Peak VO2 and VE/VCO2 slope were demonstrated with univariate Cox regression analysis both to be significant predictors of cardiac-related mortality and hospitalization (P slope in predicting cardiac-related hospitalization, but not cardiac mortality. The VE/VCO2 slope was demonstrated with receiver operating characteristic curve analysis to be significantly better than peak VO2 in predicting cardiac-related mortality (P slope was greater than peak VO2 in predicting cardiac-related hospitalization (0.77 vs 0.73), the difference was not statistically significant (P =.14). These results add to the present body of knowledge supporting the use of cardiopulmonary exercise testing in HF. Consideration should be given to revising clinical guidelines to reflect the prognostic importance of the VE/VCO2 slope in addition to peak VO2.

  10. Elite cross-country skiers do not reach their running VO2max during roller ski skating.

    Science.gov (United States)

    Losnegard, T; Hallén, J

    2014-08-01

    Cross-country skiers' VO2max is often measured during treadmill running. However, VO2max during treadmill skiing with the diagonal stride technique is higher, whereas it is lower during double poling, another classical style technique. How these values compare to VO2max during ski skating in elite cross country skiers is not known. Therefore, this study compared VO2max during treadmill uphill running and treadmill roller ski skating. Twenty-two males (21±2 years, 182±6 cm, 77±7 kg, VO2max running; 72.4±4.4 mL·kg-1·min-1) elite cross-country skiers and biathlon athletes underwent testing in both running and roller ski skating before (May) and at the end (October) of the preseason training. From May to October VO2max increased during running (3.1±4.5%, P=0.003, Effect size; ES=0.44, small) but not during roller ski skating (1.8±5.6%, P=0.13, ES=0.24, small). In May the subjects' VO2max during running was 1.7±4.7% higher compared to during roller ski skating (P=0.08, ES=0.24, small) while in October this difference was 3.0±5.0 % (Pski skating than during running and this relationship does not change during the pre-season training period.

  11. High Performance and Enhanced Durability of Thermochromic Films Using VO2@ZnO Core-Shell Nanoparticles.

    Science.gov (United States)

    Chen, Yunxiang; Zeng, Xianzhe; Zhu, Jingting; Li, Rong; Yao, Heliang; Cao, Xun; Ji, Shidong; Jin, Ping

    2017-08-23

    For VO2-based thermochromic smart windows, high luminous transmittance (Tlum) and solar regulation efficiency (ΔTsol) are usually pursued as the most critical issues, which have been discussed in numerous researches. However, environmental durability, which has rarely been considered, is also so vital for practical application because it determines lifetime and cycle times of smart windows. In this paper, we report novel VO2@ZnO core-shell nanoparticles with ultrahigh durability as well as improved thermochromic performance. The VO2@ZnO nanoparticles-based thermochromic film exhibits a robust durability that the ΔTsol keeps 77% (from 19.1% to 14.7%) after 103 hours in a hyperthermal and humid environment, while a relevant property of uncoated VO2 nanoparticles-based film badly deteriorates after 30 h. Meanwhile, compared with the uncoated VO2-based film, the VO2@ZnO-based film demonstrates an 11.0% increase (from 17.2% to 19.1%) in ΔTsol and a 31.1% increase (from 38.9% to 51.0%) in Tlum. Such integrated thermochromic performance expresses good potential for practical application of VO2-based smart windows.

  12. Effect of blood haemoglobin concentration on V(O2,max) and cardiovascular function in lowlanders acclimatised to 5260 m

    DEFF Research Database (Denmark)

    Calbet, J A L; Rådegran, G; Boushel, Robert Christopher

    2002-01-01

    )) and the measurements were repeated, increasing the work rate as tolerated. Hyperoxia increased maximal power output and leg V(O(2),max), showing that breathing ambient air at 5260 m, V(O(2),max) is limited by the availability of O(2) rather than by muscular oxidative capacity. Altitude increased [Hb] by 36 % from 136...... and maximal V(O(2)) was thus maintained by higher O(2) extraction. While CO increased linearly with work rate irrespective of [Hb] or inspired oxygen fraction (F(I,O(2))), both LBF and leg vascular conductance were systematically higher when [Hb] was low. Close and significant relationships were seen between...

  13. CLAS App ML

    NARCIS (Netherlands)

    Maher, Bridget; Hartkopf, Kathleen; Stieger, Lina; Schroeder, Hanna; Sopka, Sasa; Orrego, Carola; Drachsler, Hendrik

    2014-01-01

    This is a multi-language (ML) update of the CLAS App original design by Bridget Maher from the School of Medicine at University College Cork, Ireland. The current version has an improve counting mechanism and has been translated from English to Spanish, Catalan and German languages within the

  14. The effects of uphill vs. level-grade high-intensity interval training on VO2max, Vmax, V(LT), and Tmax in well-trained distance runners.

    Science.gov (United States)

    Ferley, Derek D; Osborn, Roy W; Vukovich, Matthew D

    2013-06-01

    Uphill running represents a frequently used and often prescribed training tactic in the development of competitive distance runners but remains largely uninvestigated and unsubstantiated as a training modality. The purpose of this investigation included documenting the effects of uphill interval training compared with level-grade interval training on maximal oxygen consumption (VO2max), the running speed associated with VO2max (Vmax), the running speed associated with lactate threshold (V(LT)), and the duration for which Vmax can be sustained (Tmax) in well-trained distance runners. Thirty-two well-trained distance runners (age, 27.4 ± 3.8 years; body mass, 64.8 ± 8.9 kg; height, 173.6 ± 6.4 cm; and VO2max, 60.9 ± 8.5 ml·min(-1)·kg(-1)) received assignment to an uphill interval training group (G(Hill) = 12), level-grade interval training group (G(Flat) = 12), or control group (G(Con) = 8). G(Hill) and G(Flat) completed 12 interval and 12 continuous running sessions over 6 weeks, whereas G(Con) maintained their normal training routine. Pre- and posttest measures of VO2max, Vmax, V(LT), and Tmax were used to assess performance. A 3 × 2 repeated measures analysis of variance was performed for each dependent variable and revealed a significant difference in Tmax in both G(Hill) and G(Flat) (p VO2max but that traditional level-grade training produces greater gains.

  15. Relation of oxygen uptake to work rate in prepubertal healthy children - reference for VO2/W-slope and effect on cardiorespiratory fitness assessment.

    Science.gov (United States)

    Tompuri, Tuomo; Lintu, Niina; Laitinen, Tomi; Lakka, Timo A

    2017-08-09

    Exercise testing by cycle ergometer allows to observe the interaction between oxygen uptake (VO2 ) and workload (W), and VO2 /W-slope can be used as a diagnostic tool. Respectively, peak oxygen uptake (VO2PEAK ) can be estimated by maximal workload. We aim to determine reference for VO2 /W-slope among prepubertal children and define agreement between estimated and measured VO2PEAK . A total of 38 prepubertal children (20 girls) performed a maximal cycle ergometer test with respiratory gas analysis. VO2 /W-slopes were computed using linear regression. Agreement analysis by Bland and Altman for estimated and measured VO2PEAK was carried out including limits of agreement (LA). Determinants for VO2 /W-slopes and estimation bias were defined. VO2/W-slope was in both girls and boys ≥9·4 and did not change with exercise level, but the oxygen cost of exercise was higher among physically more active children. Estimated VO2PEAK had 6·4% coefficient of variation, and LA varied from 13% underestimation to 13% overestimation. Bias had a trend towards underestimation along lean mass proportional VO2PEAK . The primary determinant for estimation bias was VO2/W-slope (β = -0·65; PW-slope among healthy prepubertal children were similar to those published for adults and among adolescents. Estimated and measured VO2PEAK should not be considered to be interchangeable because of the variation in the relationship between VO2 and W. On other hand, variation in the relationship between VO2 and W enables that VO2 /W-slope can be used as a diagnostic tool. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  16. Voltage triggered resistance switching in two terminal VO2 nano-junctions fabricated by electron-beam lithography

    Science.gov (United States)

    Gopalakrishnan, Gokul; Ruzmetov, Dmitry; Ko, Changhyun; Narayanamurti, Venkatesh; Ramanathan, Shriram

    2010-03-01

    Vanadium dioxide (VO2) thin films have been shown to undergo an abrupt decrease in resistivity, both in response to increasing temperature as well as an increasing electric field. The ultra-fast electrically triggered transition has made VO2 an exciting platform to explore a range of potential applications, from high speed switches to memory elements. Particularly valuable to such investigation is characterization of the electronic properties of VO2 thin films, in which transport is additionally constrained within nanoscale dimensions along the in-plane directions. In this poster, we describe the results of transport measurements on VO2 nanojunctions grown on a conductive substrate and patterned by electron-beam lithography. We analyze the out-of-plane I-V data and present a detailed discussion on electron transport mechanisms and on the origin behind the electrically triggered conductivity jumps that we observe in these nano-junctions.

  17. Suppression of metal-insulator transition in VO2 by electric field-induced oxygen vacancy formation

    National Research Council Canada - National Science Library

    Jeong, Jaewoo; Aetukuri, Nagaphani; Graf, Tanja; Schladt, Thomas D; Samant, Mahesh G; Parkin, Stuart S P

    2013-01-01

    .... We found that electrolyte gating of VO(2) leads not to electrostatically induced carriers but instead to the electric field-induced creation of oxygen vacancies, with consequent migration of oxygen from the oxide film into the ionic liquid...

  18. Resistance switching of epitaxial VO2/Al2O3 heterostructure at room temperature induced by organic liquids

    Directory of Open Access Journals (Sweden)

    Mengmeng Yang

    2015-03-01

    Full Text Available We studied using organic liquids (cyclohexane, n-butanol, and ethylene glycol to modulate the transport properties at room temperature of an epitaxial VO2 film on a VO2/Al2O3 heterostructure. The resistance of the VO2 film increased when coated with cyclohexane or n-butanol, with maximum changes of 31% and 3.8%, respectively. In contrast, it decreased when coated with ethylene glycol, with a maximum change of −7.7%. In all cases, the resistance recovered to its original value after removing the organic liquid. This organic-liquid-induced reversible resistance switching suggests that VO2 films can be used as organic molecular sensors.

  19. Influence of BDNF Genotype and Exercise on BDNF Serum Levels and VO2 Max after Acute Exercise and Post Training

    Science.gov (United States)

    2017-07-29

    across age and gender groups [12,13,14,15,16]. Exercise-based cognitive augmentation is thought to be mediated by BDNF [17,18]. BDNF is a...effectively discriminated since the results are consistent above the prior probabilities in a random guess. 17 Distribution A: Approved for public...significance of VO2 in discriminating between groups. Iteration B e ta 100 200 300 Intercept Allele VO_2 -30 -20 -10 0 10 20 Iteration P -v a lu e

  20. Proliferation of metallic domains caused by inhomogeneous heating near the electrically-driven transition in VO$_2$ nanobeams

    OpenAIRE

    Singh, Sujay; Horrocks, Gregory; Marley, Peter M; Shi, Zhenzhong; Banerjee, Sarbajit; Sambandamurthy, G.

    2015-01-01

    We discuss the mechanisms behind the electrically driven insulator-metal transition in single crystalline VO$_2$ nanobeams. Our DC and AC transport measurements and the versatile harmonic analysis method employed show that non-uniform Joule heating causes phase inhomogeneities to develop within the nanobeam and is responsible for driving the transition in VO$_{2}$. A Poole-Frenkel like purely electric field induced transition is found to be absent and the role of percolation near and away fro...

  1. Athletes with higher VO2max present reduced oxLDL after a marathon race.

    Science.gov (United States)

    Bachi, André L L; Sierra, Ana Paula R; Rios, Francisco J O; Gonçalves, Danieli A; Ghorayeb, Nabil; Abud, Ronaldo L; Victorino, Angélica B; Dos Santos, Juliana M B; Kiss, Maria Augusta D P; Pithon-Curi, Tania C; Vaisberg, Mauro

    2015-01-01

    During a session of prolonged and exhaustive exercise, such as a marathon race, large quantities of free radicals are produced and can oxidise (ox) several molecules, such as low-density lipoprotein (LDL). To prevent oxidative damage, athletes present higher antioxidant levels. However, the effect of marathon running on the natural IgM or IgG anti-oxLDL autoantibodies is not understood. Thus, we investigated the effect of a marathon race on oxidative stress and the mechanisms of control of this stress. Blood samples of 20 marathon runners were collected 24 hours before, immediately and 72 hours after a marathon race to evaluate: plasma lipid profile; serum levels of oxLDL and anti-oxLDL autoantibodies (IgM and IgG isotype) and total antioxidant capacity (TAC). Maximum oxygen uptake (VO2max) was also determined. Immediately after the race, oxLDL and TAC levels decreased in comparison to the basal levels; however, the IgM or IgG anti-oxLDL levels remain unchanged. Whereas no differences were observed in the IgM or IgG anti-oxLDL levels 72h after the marathon, the oxLDL and TAC levels returned to the basal values. Significant positive correlations were observed between oxLDL and LDL-cholesterol before, and 72h after the marathon. Significant negative correlations were observed between oxLDL and VO2max immediately after the marathon and 72 h later, as well as between oxLDL and TAC 72 h after the race. Athletes with a higher VO2max and total antioxidant activity presented reduced LDL oxidation. The levels of IgM or IgG anti-oxLDL autoantibodies were not affected by running the marathon.

  2. Greater prognostic value of peak VO2 after exercise training program completion in heart failure patients.

    Science.gov (United States)

    Tabet, Jean-Yves; Meurin, Philippe; Benzidi, Younes; Beauvais, Florence; Ben Driss, Ahmed; Weber, Hélène; Renaud, Nathalie; Dumaine, Raphaelle; Grosdemouge, Anne; Cohen Solal, Alain

    2013-10-09

    Exercise capacity, best reflected by peak exercise oxygen consumption (peak VO(2)), is a powerful prognostic factor in patients with chronic heart failure (CHF). However, the optimal time to assess exercise capacity for prognosis remains unclear and whether an exercise training program (ETP) to improve exercise capacity alters the prognostic value of cardiopulmonary exercise (CPX) testing variables in CHF is unknown. CHF patients who underwent an ETP in two cardiac rehabilitation centers between 2004 and 2009 were prospectively included, and CPX testing was performed before and after ETP completion. We included 285 consecutive patients who underwent an ETP (19.4 ± 8.7 training sessions in 4 to 10 weeks), including segmental gymnastics and cycling sessions. During follow-up (12 months), 14 patients died, 6 underwent cardiac transplantation and 15 were hospitalized for acute heart failure. Univariate analysis and receiver operating characteristic (ROC) curve analysis showed that CPX variables, especially peak oxygen consumption and circulatory power (product of peak VO(2) × peak systolic blood pressure) before and after ETP completion predicted prognosis. However, CPX data obtained after ETP completion had the best prognostic value (area under the ROC curve = 0.79 ± 0.03 for peak VO(2) after ETP completion vs 0.64 ± 0.04 before ETP completion, p < 0.0001). The results did not change even when considering only deaths. In patients with stable CHF who can exercise, the prognostic value of CPX data seems greater after versus before completion of a hospital-based ETP. Therefore, CPX capacity for prognostic purposes should at best be assessed after cardiac rehabilitation. © 2013.

  3. Increased thermogenic response to food and fat oxidation in female athletes: relationship with VO(2 max).

    Science.gov (United States)

    López, P; Ledoux, M; Garrel, D R

    2000-09-01

    The thermogenic response to food (TRF) and substrate oxidation were studied in 12 endurance-trained and 13 untrained female subjects. Energy expenditure and substrate oxidation were calculated by indirect calorimetry before and for 6 h after an oral test meal and after the same meal given intragastrically on a separate occasion. The TRF was calculated after the oral meal, the obligatory component after the intragastric meal (OTRF), and the facultative component from the difference between the two. VO(2 max) was measured on a treadmill and body composition by underwater weighing. The TRF and OTRF were significantly higher in trained than in untrained subjects: 223 +/- 63 vs. 185 +/- 50 kJ/6 h (P < 0.03) and 174 +/- 38 vs. 131 +/- 37 kJ/6 h (P < 0.01) for the TRF and OTRF in trained vs. untrained subjects, respectively. Multiple regression analysis showed that maximum O(2) consumption (VO(2 max)), but not percentage of body fat, was significantly related to OTRF (r =0.68, P < 0.01). Trained subjects had higher fatty acid oxidation than untrained subjects before (0.6 vs. 0.4 mg. kg(-1). min(-1), P < 0.05) and after the oral meal (13 +/- 6 vs. 8 +/- 4 g/6 h P < 0.05). These results demonstrate that 1) TRF is higher in trained than in untrained women; 2) this is due to a higher cost of nutrient digestion, absorption and storage; 3) the difference is related to higher VO(2 max); and 4) fatty acid oxidation is greater in trained women in both the postabsorptive and postprandial states. These observations suggest that endurance training induces metabolic changes that favor leanness.

  4. Athletes with higher VO2max present reduced oxLDL after a marathon race

    Science.gov (United States)

    Bachi, André L L; Sierra, Ana Paula R; Rios, Francisco J O; Gonçalves, Danieli A; Ghorayeb, Nabil; Abud, Ronaldo L; Victorino, Angélica B; dos Santos, Juliana M B; Kiss, Maria Augusta D P; Pithon-Curi, Tania C; Vaisberg, Mauro

    2015-01-01

    Background During a session of prolonged and exhaustive exercise, such as a marathon race, large quantities of free radicals are produced and can oxidise (ox) several molecules, such as low-density lipoprotein (LDL). To prevent oxidative damage, athletes present higher antioxidant levels. However, the effect of marathon running on the natural IgM or IgG anti-oxLDL autoantibodies is not understood. Thus, we investigated the effect of a marathon race on oxidative stress and the mechanisms of control of this stress. Methods Blood samples of 20 marathon runners were collected 24 hours before, immediately and 72 hours after a marathon race to evaluate: plasma lipid profile; serum levels of oxLDL and anti-oxLDL autoantibodies (IgM and IgG isotype) and total antioxidant capacity (TAC). Maximum oxygen uptake (VO2max) was also determined. Results Immediately after the race, oxLDL and TAC levels decreased in comparison to the basal levels; however, the IgM or IgG anti-oxLDL levels remain unchanged. Whereas no differences were observed in the IgM or IgG anti-oxLDL levels 72h after the marathon, the oxLDL and TAC levels returned to the basal values. Significant positive correlations were observed between oxLDL and LDL-cholesterol before, and 72h after the marathon. Significant negative correlations were observed between oxLDL and VO2max immediately after the marathon and 72 h later, as well as between oxLDL and TAC 72 h after the race. Conclusions Athletes with a higher VO2max and total antioxidant activity presented reduced LDL oxidation. The levels of IgM or IgG anti-oxLDL autoantibodies were not affected by running the marathon. PMID:27900109

  5. Applicability of an Indirect VO2max Test: Its Association with the 400 Meters Freestyle Performance

    Directory of Open Access Journals (Sweden)

    Adalberto Veronese da Costa

    Full Text Available Abstract The aim of this study was to evaluate the VO2max using a previously validated indirect test for non-expert adult swimmers and to verify its connection with the 400 meters freestyle test. A total of 17 non-expert male swimmers (21.5 ± 3.12 years were evaluated. Body composition measurements included body weight (74 ± 9.41 kg, height (172.9 ± 5.21 cm and body fat percentage (15.2 ± 4.15 %. Two tests were conducted on different days; the 400 meters freestyle (400 MF and the Progressive Swim Test (PSwT, respectively. The participant's heart rate frequency before and after the test (BHR and AHR was analyzed, as well as the subjective perception of effort (RPE, the number of laps covered (NLP, and the time of test execution measured in minutes. Significant differences were identified in all variables (p - 0.60 was found between AHR and execution time (r > - 0.70, as well as between the VO2max estimated by the PSwT and the 400 MF performance test (r > - 0.70. The Bland-Altman Plot showed that the values discovered were within the established concordance limits of 95% (±1.96 SD. A negative correlation between a swimming test and a test that estimates the VO2max occurred, and the PSwT showed results of greater approximation of the aerobic power of non-expert swimmers. In conclusion, the PSwT is applicable for non-expert adult swimmers.

  6. Individual versus Standardized Running Protocols in the Determination of VO2max.

    Science.gov (United States)

    Sperlich, Paula F; Holmberg, Hans-Christer; Reed, Jennifer L; Zinner, Christoph; Mester, Joachim; Sperlich, Billy

    2015-06-01

    The purpose of this study was to determine whether an individually designed incremental exercise protocol results in greater rates of oxygen uptake (VO2max) than standardized testing. Fourteen well-trained, male runners performed five incremental protocols in randomized order to measure their VO2max: i) an incremental test (INCS+I) with pre-defined increases in speed (2 min at 8.64 km·h(-1), then a rise of 1.44 km·h(-1) every 30 s up to 14.4 km·h(-1)) and thereafter inclination (0.5° every 30 s); ii) an incremental test (INCI) at constant speed (14.4 km·h(-1)) and increasing inclination (2° every 2 min from the initial 0°); iii) an incremental test (INCS) at constant inclination (0°) and increasing speed (0.5 km·h(-1) every 30 s from the initial 12.0 km·h(-1)); iv) a graded exercise protocol (GXP) at a 1° incline with increasing speed (initially 8.64 km·h(-1) + 1.44 km·h(-1) every 5 min); v) an individual exercise protocol (INDXP) in which the runner chose the inclination and speed. VO2max was lowest (-4.2%) during the GXP (p = 0.01; d = 0.06-0.61) compared to all other tests. The highest rating of perceived exertion, heart rate, ventilation and end-exercise blood lactate concentration were similar between the different protocols (p VO2max attained by employing an individual treadmill protocol does not differ from the values derived from various standardized incremental protocols. Key pointsThe mean maximum oxygen uptake during the GXP was lower than for all other tests.Differences in the maximum rate of oxygen uptake between the various protocols exhibited considerable inter-individual variation.From the current findings, it can be concluded that well trained athletes are able to perform an individually designed treadmill running protocol.

  7. Dynamic Control of Light Emission Faster than the Lifetime Limit Using VO2 Phase-Change

    Science.gov (United States)

    2015-10-22

    Pol, polarization; SP, short-pass; SPAD, single-photon avalanche photodiode; trig., trigger. Control laser on VO2 metallic phase aMD=21% Control...optoelectronics and nanophotonics. Methods Device fabrication. A 145-nm-thick Y2O3 buffer-layer was deposited by e-beam evaporation followed by a 50-nm...activate the Er3þ ions and crystallize the Y2O3. A TiO2 spacer layer was subsequently deposited by reactively sputtering a pure titanium target under

  8. Modality determines VO2max achieved in self-paced exercise tests: validation with the Bruce protocol.

    Science.gov (United States)

    Hanson, Nicholas J; Scheadler, Cory M; Lee, Taylor L; Neuenfeldt, Noah C; Michael, Timothy J; Miller, Michael G

    2016-07-01

    The Bruce protocol is traditionally used to assess maximal cardiorespiratory fitness (VO2max), but may have limitations, such as an unknown duration and large work rate increases. The use of self-paced VO2max tests (SPVs) may be beneficial if they are able to elicit similar maximal values in a set period of time. In addition, differences in modality between SPVs have not been explored. The purpose of this study was to compare SPVs, utilizing two different modes, with the Bruce (treadmill) protocol. Thirteen healthy, recreationally active individuals (eight men, five women) volunteered and participated in three different laboratory visits with each utilizing a different VO2max testing protocol. The first visit consisted of the Bruce protocol test, and the remaining visits entailed a maximal SPV on a treadmill (TM SPV) and a cycle ergometer (CE SPV). There were no differences in VO2max values between the TM SPV and the Bruce protocol tests (55.6 ± 4.9 vs. 56.2 ± 6.8, respectively; p = .510). As expected, the CE SPV (48.3 ± 7.6) was significantly lower than the other two tests (p VO2max as the Bruce protocol and did so with less incline and in less time suggesting that there are no changes in the limits of VO2max even when the test is self-paced and perceptually regulated.

  9. Optimizing thermochromic VO2 by co-doping with W and Sr for smart window applications

    Science.gov (United States)

    Dietrich, Marc K.; Kuhl, Florian; Polity, Angelika; Klar, Peter J.

    2017-04-01

    Smart windows possess the potential to contribute significantly to reducing the world-wide energy consumption in the future. The properties of the thermochromic metal oxide VO2 are closest to the material requirements set by economic considerations for the use as an active layer in thermochromic glazings. We show that the required parameters can be achieved by modifying VO2 on the atomic level, i.e., by simultaneous co-doping with Sr and W on the cation site. In particular, the transition temperature ϑ c can be adjusted in the range between 15 and 68 °C by varying W contents, whereas the incorporation of Sr mainly increases the band gap yielding a greyish color of the films. Interestingly, the simultaneous presence of W and Sr enhances both effects. The co-doping leads to values of the luminous transmittance T lum and the solar transmittance T sol fulfilling the requirements set by application. The variation of the solar transmittance Δ T sol of the plain thin films on a glass substrate already is larger than 5% for all samples promising that the required value of Δ T sol = 10 % is achievable by using such thin films as part of an optically engineered multilayer system.

  10. Exercise tolerance during VO2max testing is a multifactorial psychobiological phenomenon.

    Science.gov (United States)

    Midgley, Adrian W; Earle, Keith; McNaughton, Lars R; Siegler, Jason C; Clough, Peter; Earle, Fiona

    2017-01-01

    Fifty-nine men completed a VO2max test and a questionnaire to establish reasons for test termination, perceived exercise reserve (difference between actual test duration and the duration the individual perceived could have been achieved if continued until physical limitation), and perception of verbal encouragement. Participants gave between 1 and 11 factors as reasons for test termination, including leg fatigue, various perceptions of physical discomfort, safety concerns, and achievement of spontaneously set goals. The two most common main reasons were leg fatigue and breathing discomfort, which were predicted by pre-to-post test changes in pulmonary function (p = 0.038) and explosive leg strength (p = 0.042; R2 = 0.40). Median (interquartile range) perceived exercise reserve, was 45 (50) s. Two-thirds of participants viewed verbal encouragement positively, whereas one-third had a neutral or negative perception. This study highlights the complexity of exercise tolerance during VO2max testing and more research should explore these novel findings.

  11. Large phonon entropy drives the metallization of vanadium dioxide (VO2)

    Science.gov (United States)

    Hong, Jiawang

    2015-03-01

    Vanadium dioxide (VO2) exhibits a first-order metal-insulator transition (MIT) near room temperature, where conductivity is suppressed and the lattice changes from tetragonal to monoclinic on cooling. This MIT in VO2 has attracted intense interest from both fundamental and technological perspectives. However, most studies performed in the past 50 years have focused on the electronic structure and energetics of the transition, ignoring the role of phonons and their entropic contribution to the phase stability. Much of the reason is that the standard tool of neutron scattering does not yield coherent scattering from V nuclei, and first-principles methods with harmonic approximation cannot capture the stable phonons for the rutile phase. We close this gap by using a combination of ab initio molecular dynamics calculations and neutron/x-ray scattering to establish that the entropy driving the MIT is dominated by soft, anharmonic phonons of the metallic phase. The MIT results from the competition between lower electronic energy in insulating M1 phase due to the Peierls instability, and the higher entropy of the metallic rutile phase resulting from soft anharmonic phonons. This understanding of the role of lattice dynamics and their relationship to electronic structure provides a critical component for developing more complete physical models of phase competition in functional transition metal oxides. Theoretical calculations were performed using the NERSC at LBNL. Modeling of neutron data was performed in CAMM, measurements were funded by the US DOE, BES, Materials Science and Engineering Division.

  12. Axially engineered metal-insulator phase transition by graded doping VO2 nanowires.

    Science.gov (United States)

    Lee, Sangwook; Cheng, Chun; Guo, Hua; Hippalgaonkar, Kedar; Wang, Kevin; Suh, Joonki; Liu, Kai; Wu, Junqiao

    2013-03-27

    The abrupt first-order metal-insulator phase transition in single-crystal vanadium dioxide nanowires (NWs) is engineered to be a gradual transition by axially grading the doping level of tungsten. We also demonstrate the potential of these NWs for thermal sensing and actuation applications. At room temperature, the graded-doped NWs show metal phase on the tips and insulator phase near the center of the NW, and the metal phase grows progressively toward the center when the temperature rises. As such, each individual NW acts as a microthermometer that can be simply read out with an optical microscope. The NW resistance decreases gradually with the temperature rise, eventually reaching 2 orders of magnitude drop, in stark contrast to the abrupt resistance change in undoped VO2 wires. This novel phase transition yields an extremely high temperature coefficient of resistivity ~10%/K, simultaneously with a very low resistivity down to 0.001 Ω·cm, making these NWs promising infrared sensing materials for uncooled microbolometers. Lastly, they form bimorph thermal actuators that bend with an unusually high curvature, ~900 m(-1)·K(-1) over a wide temperature range (35-80 °C), significantly broadening the response temperature range of previous VO2 bimorph actuators. Given that the phase transition responds to a diverse range of stimuli-heat, electric current, strain, focused light, and electric field-the graded-doped NWs may find wide applications in thermo-opto-electro-mechanical sensing and energy conversion.

  13. A bioinspired solution for spectrally selective thermochromic VO2 coated intelligent glazing.

    Science.gov (United States)

    Taylor, Alaric; Parkin, Ivan; Noor, Nuruzzaman; Tummeltshammer, Clemens; Brown, Mark S; Papakonstantinou, Ioannis

    2013-09-09

    We present a novel approach towards achieving high visible transmittance for vanadium dioxide (VO(2)) coated surfaces whilst maintaining the solar energy transmittance modulation required for smart-window applications. Our method deviates from conventional approaches and utilizes subwavelength surface structures, based upon those present on the eyeballs of moths, that are engineered to exhibit broadband, polarization insensitive and wide-angle antireflection properties. The moth-eye functionalised surface is expected to benefit from simultaneous super-hydrophobic properties that enable the window to self-clean. We develop a set of design rules for the moth-eye surface nanostructures and, following this, numerically optimize their dimensions using parameter search algorithms implemented through a series of Finite Difference Time Domain (FDTD) simulations. We select six high-performing cases for presentation, all of which have a periodicity of 130 nm and aspect ratios between 1.9 and 8.8. Based upon our calculations the selected cases modulate the solar energy transmittance by as much as 23.1% whilst maintaining high visible transmittance of up to 70.3%. The performance metrics of the windows presented in this paper are the highest calculated for VO(2) based smart-windows.

  14. Muscle synergies during incremental rowing VO2max test of collegiate rowers and untrained subjects.

    Science.gov (United States)

    Shaharudin, Shazlin; Agrawal, Sunil

    2016-09-01

    The purpose of this study was to evaluate the muscle synergies during incremental rowing VO2 max Test of collegiate rowers and untrained subjects. As a power endurance sport, high aerobic capacity was one of the determinants of rowing performance. The modulation of muscle recruitment patterns following specific physiological demands was an indication of the robustness of muscle synergies composition which was overlooked in previous studies. Ten male collegiate rowers and physically active untrained subjects were recruited. Muscle synergies were extracted from 16 rowing-specific muscles using Principal Component Analysis with varimax rotation. Incremental rowing VO2 max Test was performed on slides ergometer (SE). Rowing performance and physiological variables were analyzed. Rowers exerted greater power output, more energy expenditure and better rowing economy compared to untrained subjects. Rowers preferred to row slower with longer strokes compared to the untrained subjects. Three muscle synergies with high indices of similarity of waveform patterns were extracted in both groups. Significant association was found between muscle synergies and rowing economy. The findings of this study showed that muscle synergies were robust during aerobic-dominant activity for collegiate rowers and untrained subjects. Rowers and coaches could utilize the findings by emphasizing on muscle coordination training, which may enhance the rowing economy.

  15. Efeito da intensidade do exercício de corrida intermitente 30s:15s no tempo de manutenção no ou próximo do VO2max Effect of intensity of intermittent running exercise 30s:15s at the time maintenance at or near VO2max

    OpenAIRE

    Rafael Alves De Aguiar; Jardel Schlickmann; Tiago Turnes; Fabrizio Caputo

    2013-01-01

    O presente estudo comparou o tempo mantido acima de 90% (t90VO2max) e de 95% VO2max (t95VO2max) em três diferentes intensidades de exercício. Após a realização de um teste incremental para determinar o VO2max, oito estudantes de educação física ativos (23 ± 3 anos) executaram três sessões de exercícios intermitentes (100, 110 e 120% da velocidade do VO2max (vVO2max)) com razão esforço:recuperação de 30s:15s. O t95VO2max foi significantemente maior em 110%vVO2max (EI110%) (218,1 ± 81,6 s) quan...

  16. EPR and optical absorption studies of paramagnetic molecular ion (VO2+) in Lithium Sodium Acid Phthalate single crystal

    Science.gov (United States)

    Subbulakshmi, N.; Kumar, M. Saravana; Sheela, K. Juliet; Krishnan, S. Radha; Shanmugam, V. M.; Subramanian, P.

    2017-12-01

    Electron Paramagnetic Resonance (EPR) spectroscopic studies of VO2+ ions as paramagnetic impurity in Lithium Sodium Acid Phthalate (LiNaP) single crystal have been done at room temperature on X-Band microwave frequency. The lattice parameter values are obtained for the chosen system from Single crystal X-ray diffraction study. Among the number of hyperfine lines in the EPR spectra only two sets are reported from EPR data. The principal values of g and A tensors are evaluated for the two different VO2+ sites I and II. They possess the crystalline field around the VO2+ as orthorhombic. Site II VO2+ ion is identified as substitutional in place of Na1 location and the other site I is identified as interstitial location. For both sites in LiNaP, VO2+ are identified in octahedral coordination with tetragonal distortion as seen from the spin Hamiltonian parameter values. The ground state of vanadyl ion in the LiNaP single crystal is dxy. Using optical absorption data the octahedral and tetragonal parameters are calculated. By correlating EPR and optical data, the molecular orbital bonding parameters have been discussed for both sites.

  17. Caffeine effects on VO2max test outcomes investigated by a placebo perceived-as-caffeine design.

    Science.gov (United States)

    Brietzke, Cayque; Asano, Ricardo Yukio; De Russi de Lima, Felipe; Pinheiro, Fabiano Aparecido; Franco-Alvarenga; Ugrinowitsch, Carlos; Pires, Flávio Oliveira

    2017-12-01

    Ergogenic effects of caffeine (CAF) ingestion have been observed in different cycling exercise modes, and have been associated with alterations in ratings of perceived exertion (RPE). However, there has been little investigation of maximal oxygen uptake (VO2MAX) test outcomes. This study aimed to verify whether CAF may reduce RPE, thereby improving maximal incremental test (MIT) outcomes such as VO2MAX, time to exhaustion and peak power output (WPEAK). Nine healthy individuals performed three MITs (25 W/min until exhaustion) in a random, counterbalanced fashion after ingestion of CAF, placebo perceived as caffeine (PLA), and no supplementation (baseline control). VO2 was measured throughout the test, while RPE was rated according to overall and leg effort sensations. The power output corresponding to submaximal (RPE = 14 according to the 6-20 Borg scale) and maximal RPE was recorded for both overall (O-RPE14 and O-RPEMAX) and leg RPE (L-RPE14 and L-RPEMAX). VO2MAX did not change significantly between MITs; however, CAF and PLA increased time to exhaustion (↑ ∼18.7% and ∼17.1%, respectively; p VO2MAX values. CAF effects were attributed to placebo.

  18. First-principles investigation on solar radiation shielding performance of rutile VO2 filters for smart windows

    Science.gov (United States)

    Xiao, Lihua; Su, Yuchang; Qiu, Wei; Ran, Jingyu; Liu, Yike; Wu, Jianming; Lu, Fanghai; Shao, Fang; Peng, Ping

    2016-11-01

    Vanadium dioxide (VO2) undergoing reversible metal-insulator phase transition could allow for the formation of an efficient thermochromic material for smart windows. However, solar radiation shielding performance is determined by transparent rutile VO2 filters, and the puzzling metal-insulator transition mechanism makes it challenging to explain the origin of the coexistence of strong near infrared absorption with high optical transparency. The band structure, the density of states, and the optical properties of rutile VO2 were calculated using the first-principles calculations. The calculated results of the structural and optical properties are in good agreement with the previously reported experimental findings. The calculated dielectric functions, electron energy-loss function and solar radiation shielding performance of the rutile VO2 filters indicate that rutile VO2 is a promising near-infrared absorption/reflectance material with the near-infrared radiation insulating abilities and a visible light transmittance. These properties arise from plasma oscillation and a collective oscillation (volume plasmons) of carrier electrons.

  19. DC sputtered W-doped VO2 thermochromic thin films for smart windows with active solar control.

    Science.gov (United States)

    Batista, C; Ribeiro, R; Carneiro, J; Teixeira, V

    2009-07-01

    Doped VO2 thin films, with different W at.% and consequent dissimilar transition temperatures, were successfully deposited onto SiO2-coated float-glass substrates by reactive direct current (DC) magnetron sputtering. Structural analyses have shown, for undoped films, single phase VO2(M) films with c-axis (002) direction as the preferred crystal orientation. The addition of tungsten into the VO2 solid solution favored the crystallization in the (011) direction which became dominant above a critical level of dopant concentration. The surface morphology of pure VO2 films revealed elongated grains oriented within the film plane. The doped films evidenced an increased tendency to be oriented out of the film plane which has resulted in increased roughness levels. The doping methodology associated with optimized processing conditions allowed the production of W-doped VO2 films with reduced transition temperatures, from 63 down to 28 degrees C, and maximum transmittances at the visible region ranging 40%. The relationship between tungsten content in the film and consequent transition temperature expressed a linear behavior.

  20. Enhanced Visible Transmittance of Thermochromic VO2 Thin Films by SiO2 Passivation Layer and Their Optical Characterization

    Directory of Open Access Journals (Sweden)

    Jung-Hoon Yu

    2016-07-01

    Full Text Available This paper presents the preparation of high-quality vanadium dioxide (VO2 thermochromic thin films with enhanced visible transmittance (Tvis via radio frequency (RF sputtering and plasma enhanced chemical vapor deposition (PECVD. VO2 thin films with high Tvis and excellent optical switching efficiency (Eos were successfully prepared by employing SiO2 as a passivation layer. After SiO2 deposition, the roughness of the films was decreased 2-fold and a denser structure was formed. These morphological changes corresponded to the results of optical characterization including the haze, reflectance and absorption spectra. In spite of SiO2 coating, the phase transition temperature (Tc of the prepared films was not affected. Compared with pristine VO2, the total layer thickness after SiO2 coating was 160 nm, which is an increase of 80 nm. Despite the thickness change, the VO2 thin films showed a higher Tvis value (λ 650 nm, 58% compared with the pristine samples (λ 650 nm, 43%. This enhancement of Tvis while maintaining high Eos is meaningful for VO2-based smart window applications.

  1. Escala de VO2pico em adolescentes obesos e não-Obesos por diferentes métodos Escala de VO2pico en adolescentes obesos y no obesos por diferentes métodos Scale of VO2peak in obese and non-obese adolescents by different methods

    Directory of Open Access Journals (Sweden)

    Gerusa Eisfeld Milano

    2009-12-01

    Full Text Available FUNDAMENTO: O consumo de oxigênio de pico (VO2pico pode ser definido como a maior taxa de consumo de oxigênio durante exercício exaustivo ou máximo. A avaliação da aptidão aeróbica pode ser expressa como relativa à massa corporal, mas esse procedimento pode não remover completamente as diferenças quando indivíduos pesados são avaliados. Assim, o procedimento com escala alométrica é uma estratégia atraente para comparar indivíduos com grandes diferenças em massa corporal. OBJETIVO: Investigar o VO2pico em indivíduos obesos e não-obesos usando o método de correção de massa corporal (convencional e escala alométrica (método alométrico e, como esses métodos são aplicados quando indivíduos de ambos os sexos se exercitam em uma esteira ergométrica. MÉTODOS: O VO2pico relativo ao peso corporal e pelo método alométrico foi comparado em 54 adolescentes obesos e 33 não-obesos (10 a 16 anos. Calorimetria indireta foi usada para avaliar o VO2pico durante um teste máximo. O expoente alométrico foi calculado levando-se em consideração a massa corporal individual. Então o VO2pico foi corrigido pelo expoente alométrico. As comparações foram realizadas usando-se two-way ANOVA para medidas repetidas (p0,05. Entretanto, o VO2pico calculado pelo método convencional foi maior (p0,05 entre os grupos. CONCLUSÃO: Indivíduos obesos apresentaram VO2pico mais baixo do que os não-obesos, quando avaliados pelo método convencional. Entretanto, quando o método da escala alométrica foi aplicado, as diferenças desapareceram.FUNDAMENTO: El consumo pico de oxígeno (VO2pico puede ser definido como la mayor tasa de consumo de oxígeno durante ejercicio exhaustivo o máximo. La evaluación de aptitud aeróbica puede expresarse como relativa a la masa corporal, pero ese procedimiento puede no resolver completamente las diferencias cuando se evalúan individuos pesados. Por ello, el procedimiento con escala alométrica es una

  2. Why the Heyd-Scuseria-Ernzerhof hybrid functional description of VO2 phases is not correct

    KAUST Repository

    Grau-Crespo, Ricardo

    2012-08-06

    In contrast with recent claims that the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid functional can provide a good description of the electronic and magnetic structures of VO2 phases, we show here that the HSE lowest-energy solutions for both the low-temperature monoclinic (M1) phase and the high-temperature rutile (R) phase, which are obtained upon inclusion of spin polarization, are at odds with experimental observations. For the M1 phase the ground state is (but should not be) magnetic, while the ground state of the R phase, which is also spin polarized, is not (but should be) metallic. The energy difference between the low-temperature and high-temperature phases has strong discrepancies with the experimental latent heat.

  3. Determinants of time limit at velocity corresponding to VO2max in physically active individuals

    Directory of Open Access Journals (Sweden)

    Jefferson da Silva Novaes

    2008-01-01

    Full Text Available The objective of the present study was to determine the relationship between time limit (Tlim at VO2Máx velocity (VVO2Máx and the variables VO2Máx, VVO2Máx, running economy (RE, ventilatory threshold (VT, strength test (9-10 maximum repetitions, velocity at maximal anaerobic running test (VMART, vertical jump test and body fat percentage. The sample was composed of 18 male volunteers, aged between 18 and 45 years old, non-athletes, but physically active. The study was carried out during fi ve visits, on non-consecutive days and at approximately the same time each day: visit 1 - signature of informed consent form, medical history, anthropometric assessment, aerobic power test and familiarization with Tlim test; visit 2 - RE test and Tlim test; visit 3 - familiarization with VMART test; visit 4 - familiarization with vertical jump and 9-10 maximum repetition tests and VMART test; visit 5 - vertical jump and 9-10 maximum repetition tests. Low (r = 0.220 to – 0.359 and non-significant correlations (p = 0.281 to 0.935 were observed between Tlim and the selected variables, characterizing the low predictive value of Tlim for the sample studied. Thus, and because of the considerable inter-individual variability in Tlim, no variable was identified that was capable of satisfactorily predicting Tlim. Resumo O objetivo do presente estudo foi determinar a relação do tempo limite (Tlim na velocidade do VO2Máx (VVO2Máx com as variáveis VO2Máx, VVO2Máx, economia de corrida (EC, limiar ventilatório (LV, força isotônica (determinada pelo teste de 9-10 RM, velocidade no teste máximo de corrida anaeróbica (VMART, impulsão vertical e percentual de gordura (%G . A amostra foi composta por 18 voluntários do sexo masculino, com idade entre 18 e 45 anos, não atletas, regularmente ativos. O estudo foi realizado em cinco visitas, em dias não consecutivos e aproximadamente no mesmo horário, compostas de: visita 1 - assinatura do termo de

  4. Design and fabrication of a tunable infrared metamaterial absorber based on VO2 films

    Science.gov (United States)

    Liu, Zhi-min; Li, Yi; Zhang, Jiao; Huang, Ya-qin; Li, Zheng-peng; Pei, Jiang-heng; Fang, Bao-ying; Wang, Xiao-hua; Xiao, Han

    2017-09-01

    A tunable metamaterial absorber with a W/VO2 square lattice nanostructure is designed and fabricated. With the excitation of plasma resonance, the tunable mechanism is achieved by the phase transition of vanadium dioxide. The optimal parameters are analyzed by using a finite difference time domain simulation method. The close-to-one absorption peak occurs around a wavelength of 5.28 µm, at which the difference of absorption between high and low temperatures is 89.74%. The findings also show that the absorber is polarization-independent and exhibits wide-angle absorption. The experimental results are in good agreement with the simulation. The results of this study show great potential for the application of energy and sensing metamaterial absorbers.

  5. Acute Effect of L-Carnitine Supplements on Lactate, Glucose, Saturated Oxygen and VO2max Variations in Young Males

    Directory of Open Access Journals (Sweden)

    Majid Kashef

    2017-03-01

    Full Text Available Introduction: L-carnitine may improve athlete’s performance by increasing lipids oxidation. The goal of the present study was to assess the acute impact of L-carnitine supplements on lactate, glucose, saturated oxygen and VO2max levels in young men. Methods: Ten young males completed 2 sessions of exhausting exercise (Bruce test. In the first session, the participants consumed placebo and in the second session, they consumed 3 g of L-carnitine 90 minutes before the test. The 2 sessions were 1-week apart. Then dependent parameters were measured.Results: A significant difference was detected in VO2max and lactate between the placebo and supplement groups (P  0.05 between the 2 groups. Conclusion: The present study showed that L-carnitine supplementation before exercise decreases lactate and increases VO2max in young men.

  6. Initial Weekly HRV Response is Related to the Prospective Change in VO2max in Female Soccer Players.

    Science.gov (United States)

    Esco, M R; Flatt, A A; Nakamura, F Y

    2016-06-01

    The aim of this study was to determine whether the early response in weekly measures of HRV, when derived from a smartphone application, were related to the eventual change in VO2max following an off-season training program in female soccer athletes. 9 female collegiate soccer players participated in an 11-week off-season conditioning program. In the week immediately before and after the training program, each participant performed a test on a treadmill to determine maximal oxygen consumption (VO2max). Daily measures of the log-transformed root mean square of successive R-R intervals (lnRMSSD) were performed by the participants throughout week 1 and week 3 of the conditioning program. The mean and coefficient of variation (CV) lnRMSSD values of week 1 showed small (r=- 0.13, p=0.74) and moderate (r=0.57, p=0.11), respectively, non-significant correlations to the change in VO2max at the end of the conditioning program (∆VO2max). Significant and near-perfect correlation was found between the change in the weekly mean lnRMSSD values from weeks 1 and 3 (∆lnRMSSDM) and ∆VO2max (r=0.90, p=0.002). The current results have identified that the initial change in weekly mean lnRMSSD from weeks 1 to 3 of a conditioning protocol was strongly associated with the eventual adaptation of VO2max. © Georg Thieme Verlag KG Stuttgart · New York.

  7. The effect of age-related differences in body size and composition on cardiovascular determinants of VO2max.

    Science.gov (United States)

    Carrick-Ranson, Graeme; Hastings, Jeffrey L; Bhella, Paul S; Shibata, Shigeki; Fujimoto, Naoki; Palmer, Dean; Boyd, Kara; Levine, Benjamin D

    2013-05-01

    A reduction in maximal stroke volume (SVmax) and total blood volume (TBV) has been hypothesized to contribute to the decline in maximal oxygen uptake (VO2max) with healthy aging. However, these variables have rarely been collected simultaneously in a board age range to support or refute this hypothesis. It is also unclear to what extent scaling size-related cardiovascular determinants of VO2max affects the interpretation of age-related differences. A retrospective analysis of VO2max, maximal cardiac output (QCmax), TBV, and body composition including fat-free mass (FFM) in 95 (51% M) healthy adults ranging from 19-86 years. Absolute and indexed VO2max, QCmax, and maximal heart rate decreased in both sexes with age (p ≤ .031). SVmax declined with age when scaled to total body mass or body surface area (p ≤ .047) but not when expressed in absolute levels (p = .120) or relative to FFM (p = .464). Absolute and indexed TBVs (mL/kg; mL/m(2)) were not significantly affected by age but increased with age in both sexes when scaled to FFM (p ≤ .013). A lower arteriovenous oxygen difference (a-vO2diff) contributed to the reduction in VO2max with age in treadmill exercisers (p = .004) but not in the entire cohort (p = .128). These results suggest (a) a reduction in absolute SVmax, and TBV do not contribute substantially to the age-related reduction in VO2max, which instead results from a smaller QCmax due to a lower maximal heart rate, and (b) body composition scaling methods should be used to accurately describe the effect of aging on physical function and cardiovascular variables.

  8. Specific inspiratory muscle training does not improve performance or VO2max levels in well trained rowers.

    Science.gov (United States)

    Riganas, C S; Vrabas, I S; Christoulas, K; Mandroukas, K

    2008-09-01

    The purpose of this study was to examine the effects of specific inspiratory muscle training (IMT) on inspiratory muscle strength, maximal oxygen uptake (VO2max), maximal lactate accumulation (Lmax), dyspnea sensation and rowing performance in rowers. Ninteen well-trained rowers were divided into two groups: IMT (T) and control (C). The T group, in addition to their daily rowing practice, performed IMT by means of a threshold inspiratory muscle trainer for approximately 0.5h.d(-1), 5 times a week for 6 weeks. The C group participated only in their regular daily rowing training. Prior to the initiation and at the completion of the 6-week IMT program, both groups underwent an incremental treadmill run test to determine VO2max. Maximum inspiratory mouth pressure (PImax) was measured at rest and following the VO2max test. On a separate occasion, rowing performance was evaluated by a 2000 m all-out effort on a rowing ergometer. Dyspnea sensation was assessed by a modified Borg scale and Lmax was measured by an enzymatic method. Six weeks of IMT significantly (P VO2max test in the T group. In contrast, no changes in PImax were observed in the C group during the 6-week period. No significant differences were observed between pre- and post-test values in VO2max, dyspnea sensation, Lmax, and 2000 m race time in both groups. In conclusion, six weeks of IMT increases inspiratory muscle strength by approximately 28% in highly trained rowers. However, this increase in inspiratory muscle strength does not appear to improve VO2max, dyspnea sensation during exercise, or rowing performance in well-trained rowers.

  9. Running on a lower-body positive pressure treadmill: VO2max, respiratory response, and vertical ground reaction force.

    Science.gov (United States)

    Raffalt, Peter C; Hovgaard-Hansen, Line; Jensen, Bente Rona

    2013-06-01

    This study investigated maximal oxygen consumption (VO2max) and time to exhaustion while running on a lower-body positive pressure treadmill (LBPPT) at normal body weight (BW) as well as how BW support affects respiratory responses, ground reaction forces, and stride characteristics. Twelve runners performed VO2max tests on a regular treadmill and an LBPPT. Furthermore, they performed steady-state running (10km/hr, 14 km/hr, and 18 km/hr) and high-speed running (20km/hr and 22 km/hr) at four different BWs on the LBPPT. VO2, heart rate, ventilation, and breathing frequency as well as vertical ground reaction force (vGRF) and stride characteristics were measured. VO2max could be obtained on both treadmills, although time to exhaustion was 34.5% longer on the LBPPT. VO2, ventilation, and heart rate decreased linearly with increasing BW support at steady-state running, while breathing rate remained unaffected by increasing BW support. Ground reaction force was markedly reduced with increasing BW support. The contact time decreased and flight time increased with increasing BW support. The step frequency decreased and step length increased to some extent with increasing BW support. VO2max can be achieved on an LBPPT at 100% BW with an incline-running protocol. The LBPPT is a suitable training device for athletes and allows training at high running speeds and high aerobic stimuli with the benefit of low vGRF and a near-normal movement pattern, although manipulation of gravitational weight causes some adaptations in locomotion.

  10. Metal-Insulator Phase Transition in thin VO2 films: A Look from the Far Infrared Side

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Fischer, B. M.; Thoman, A.

    Vanadium dioxide (VO2) displays a well-known metal-insulator (MI) transition at atemperature of 68oC. The MI transition in VO2 has been studied extensively by a widerange of optical, electrical, structural, and magnetic measurements. In spite of this there isstill some controversy about the nature...... the transition point. Our data shows perfect agreementwith the domain growth model, whereas the homogeneous medium model is inconsistentwith our experimental results. 1 H. S. Choi et al, Phys. Rev. B 54, 4621 (1996) 2 A. Zylbersztejn and N. F. Mott, Phys. Rev. B 11, 4383 (1975)...

  11. Effect of blood haemoglobin concentration on V(O2,max) and cardiovascular function in lowlanders acclimatised to 5260 m

    DEFF Research Database (Denmark)

    Calbet, J A L; Rådegran, G; Boushel, Robert Christopher

    2002-01-01

    of cardiac output (CO), blood pressure and muscular blood flow (LBF) during exercise. Eight Danish lowlanders (three females and five males; 24 +/- 0.6 years, mean +/- S.E.M.) performed submaximal and maximal exercise on a cycle ergometer after 9 weeks at an altitude of 5260 m (Mt Chacaltaya, Bolivia......)) and the measurements were repeated, increasing the work rate as tolerated. Hyperoxia increased maximal power output and leg V(O(2),max), showing that breathing ambient air at 5260 m, V(O(2),max) is limited by the availability of O(2) rather than by muscular oxidative capacity. Altitude increased [Hb] by 36 % from 136...

  12. ARTICLES: Nonlinear interaction of infrared waves on a VO2 surface at a semiconductor-metal phase transition

    Science.gov (United States)

    Berger, N. K.; Zhukov, E. A.; Novokhatskiĭ, V. V.

    1984-04-01

    The use of a semiconductor-metal phase transition for wavefront reversal of laser radiation was proposed. An investigation was made of nonlinear reflection of CO2 laser radiation at a phase transition in VO2. A three-wave interaction on a VO2 surface was achieved using low-power cw and pulsed CO2 lasers. In the first case, the intensity reflection coefficient was 0.5% for a reference wave intensity of 0.9 W/cm2 and in the second case, it was 42% for a threshold reference wave energy density of 0.6-0.8 mJ/cm2.

  13. The VO(2)-on kinetics in constant load exercise sub-anaerobic threshold reflects endothelial function and dysfunction in muscle microcirculation.

    Science.gov (United States)

    Maione, D; Cicero, A Fg; Bacchelli, S; Cosentino, E R; Degli Esposti, D; Manners, D N; Rinaldi, E R; Rosticci, M; Senaldi, R; Ambrosioni, E; Borghi, C

    2015-01-01

    To propose a test to evaluate endothelial function, based on VO(2) on-transition kinetics in sub-anaerobic threshold (AT) constant load exercise, we tested healthy subjects and patients with ischemic-hypertensive cardiopathy by two cardiopulmonary tests on a cycle ergometer endowed with an electric motor to overcome initial inertia: a pre-test and, after at least 24 h, one 6 min constant load exercise at 90 % AT. We measured net phase 3 VO(2)-on kinetics and, by phase 2 time constant (tau), valued endothelial dysfunction. We found shorter tau in repeated tests, shorter time between first and second test, by persisting endothelium-dependent arteriolar vasodilatation and/or several other mechanisms. Reducing load to 80 % and 90 % AT did not produce significant changes in tau of healthy volunteers, while in heart patients an AT load of 70 %, compared to 80 % AT, shortened tau (delta=4.38+/-1.65 s, p=0.013). In heart patients, no correlation was found between NYHA class, ejection fraction (EF), and the two variables derived from incremental cycle cardio-pulmonary exercise, as well as between EF and tau; while NYHA class groups were well correlated with tau duration (r=0.92, p=0.0001). Doxazosin and tadalafil also significantly reduced tau. In conclusion, the O(2) consumption kinetics during the on-transition of constant load exercise below the anaerobic threshold are highly sensitive to endothelial function in muscular microcirculation, and constitute a marker for the evaluation of endothelial dysfunction.

  14. 健康人の性・年齢別最大酸素摂取量 (VO2max) 基準域およびVO2max判定指標―反復切断法によるVO2max基準域の設定

    National Research Council Canada - National Science Library

    鈴木, 政登; 石山, 育朗; 塩田, 正俊; 町田, 勝彦

    2003-01-01

    既存の最大酸素摂取量 (VO2max) の判定基準は軍人やスポーツ選手など十分に身体鍛錬を積んだ者を対象に設定された.しかし, 現在VO2maxは健康関連体力要素の1つとして, 幼若者から高年齢者に到るまで広く普及している.従って, それらの者に適用できるVO2max判定基準およびその臨界値が求められる.本研究では...

  15. Evaluation of Maximal Oxygen Uptake and Submaximal Estimates of VO2max Before, During, and After Long Duration International Space Station Missions

    Science.gov (United States)

    2008-01-01

    Evaluation of Maximal Oxygen Uptake and Submaximal Estimates of VO2max Before, During, and After Long Duration International Space Station Missions (VO2max) will document changes in maximum oxygen uptake for crewmembers onboard the International Space Station (ISS) on long-duration missions, greater than 90 days. This investigation will establish the characteristics of VO2max during flight and assess the validity of the current methods of tracking aerobic capacity change during and following the ISS missions.

  16. phraSED-ML: A paraphrased, human-readable adaptation of SED-ML.

    Science.gov (United States)

    Choi, Kiri; Smith, Lucian P; Medley, J Kyle; Sauro, Herbert M

    2016-12-01

    Model simulation exchange has been standardized with the Simulation Experiment Description Markup Language (SED-ML), but specialized software is needed to generate simulations in this format. Text-based languages allow researchers to create and modify experimental protocols quickly and easily, and export them to a common machine-readable format. phraSED-ML language allows modelers to use simple text commands to encode various elements of SED-ML (models, tasks, simulations, and results) in a format easy to read and modify. The library can translate this script to SED-ML for use in other softwares. phraSED-ML language specification, libphrasedml library, and source code are available under BSD license from http://phrasedml.sourceforge.net/ .

  17. The effects of weekly exercise time on VO2max and resting metabolic rate in normal adults.

    Science.gov (United States)

    Gim, Mi-Na; Choi, Jung-Hyun

    2016-04-01

    [Purpose] The present study examined the effect of individual weekly exercise time on resting metabolic rate and VO2max (maximal oxygen uptake), which are important components of individual health indexes. [Subjects and Methods] Thirty healthy adults participated in this study. Questionnaires were used to divide the participants into groups based on average weekly walking. Resting metabolic rate was measured using a respiratory gas analyzer. Graded exercise tests were conducted using a treadmill, and the modified Bruce protocol was used as an exercise test method. [Results] VO2max, anaerobic threshold, and resting metabolic rate were significantly different among the groups. [Conclusion] Average weekly exercise time affected VO2max, resting metabolic rate, and anaerobic threshold, all of which are indicators of individual physical ability and health. These values increased as the individual amount of exercise increased. In addition, VO2max, resting metabolic rate, and anaerobic threshold were found to be closely correlated. These findings were consistent with the results of similar previous studies.

  18. Graded Exercise Testing Protocols for the Determination of VO2max: Historical Perspectives, Progress, and Future Considerations.

    Science.gov (United States)

    Beltz, Nicholas M; Gibson, Ann L; Janot, Jeffrey M; Kravitz, Len; Mermier, Christine M; Dalleck, Lance C

    2016-01-01

    Graded exercise testing (GXT) is the most widely used assessment to examine the dynamic relationship between exercise and integrated physiological systems. The information from GXT can be applied across the spectrum of sport performance, occupational safety screening, research, and clinical diagnostics. The suitability of GXT to determine a valid maximal oxygen consumption (VO2max) has been under investigation for decades. Although a set of recommended criteria exists to verify attainment of VO2max, the methods that originally established these criteria have been scrutinized. Many studies do not apply identical criteria or fail to consider individual variability in physiological responses. As an alternative to using traditional criteria, recent research efforts have been directed toward using a supramaximal verification protocol performed after a GXT to confirm attainment of VO2max. Furthermore, the emergence of self-paced protocols has provided a simple, yet reliable approach to designing and administering GXT. In order to develop a standardized GXT protocol, additional research should further examine the utility of self-paced protocols used in conjunction with verification protocols to elicit and confirm attainment of VO2max.

  19. Temperature and electric field induced metal-insulator transition in atomic layer deposited VO2 thin films

    Science.gov (United States)

    Tadjer, Marko J.; Wheeler, Virginia D.; Downey, Brian P.; Robinson, Zachary R.; Meyer, David J.; Eddy, Charles R.; Kub, Fritz J.

    2017-10-01

    Amorphous vanadium oxide (VO2) films deposited by atomic layer deposition (ALD) were crystallized with an ex situ anneal at 660-670 °C for 1-2 h under a low oxygen pressure (10-4 to 10-5 Torr). Under these conditions the crystalline VO2 phase was maintained, while formation of the V2O5 phase was suppressed. Electrical transition from the insulator to the metallic phase was observed in the 37-60 °C range, with an ROFF/RON ratio of up to about 750 and ΔTC ≅ 7-10 °C. Lateral electric field applied across two-terminal device structures induced a reversible phase change, with a room temperature transition field of about 25 kV/cm in the VO2 sample processed with the 2 h long O2 anneal. Both the width and slope of the field induced MIT I-V hysteresis were dependent upon the VO2 crystalline quality.

  20. Graded Exercise Testing Protocols for the Determination of VO2max: Historical Perspectives, Progress, and Future Considerations

    Directory of Open Access Journals (Sweden)

    Nicholas M. Beltz

    2016-01-01

    Full Text Available Graded exercise testing (GXT is the most widely used assessment to examine the dynamic relationship between exercise and integrated physiological systems. The information from GXT can be applied across the spectrum of sport performance, occupational safety screening, research, and clinical diagnostics. The suitability of GXT to determine a valid maximal oxygen consumption (VO2max has been under investigation for decades. Although a set of recommended criteria exists to verify attainment of VO2max, the methods that originally established these criteria have been scrutinized. Many studies do not apply identical criteria or fail to consider individual variability in physiological responses. As an alternative to using traditional criteria, recent research efforts have been directed toward using a supramaximal verification protocol performed after a GXT to confirm attainment of VO2max. Furthermore, the emergence of self-paced protocols has provided a simple, yet reliable approach to designing and administering GXT. In order to develop a standardized GXT protocol, additional research should further examine the utility of self-paced protocols used in conjunction with verification protocols to elicit and confirm attainment of VO2max.

  1. Hydrogen-incorporation stabilization of metallic VO2(R) phase to room temperature, displaying promising low-temperature thermoelectric effect.

    Science.gov (United States)

    Wu, Changzheng; Feng, Feng; Feng, Jun; Dai, Jun; Peng, Lele; Zhao, Jiyin; Yang, Jinlong; Si, Cheng; Wu, Ziyu; Xie, Yi

    2011-09-07

    Regulation of electron-electron correlation has been found to be a new effective way to selectively control carrier concentration, which is a crucial step toward improving thermoelectric properties. The pure electronic behavior successfully stabilized the nonambient metallic VO(2)(R) to room temperature, giving excellent thermoelectric performance among the simple oxides with wider working temperature ranges.

  2. Reactive pulsed-DC sputtered Nb-doped VO2 coatings for smart thermochromic windows with active solar control.

    Science.gov (United States)

    Batista, C; Carneiro, J; Ribeiro, R M; Teixeira, V

    2011-10-01

    Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive pulsed-DC magnetron sputtering. Different Nb doping amounts were introduced in the VO2 solid solution during the film growing which resulted in films with distinct semiconducting-metal phase transition temperatures. Pure VO2 showed improved thermochromic behavior as compared with VO2 films prepared by conventional DC sputtering. The transition temperatures were linearly decreased from 59 down to 34 degrees C with the increase in Nb content. However, the luminous transmittance and the infrared modulation efficiency were markedly affected. The surface morphology of the films was examined by scanning electron microscopy (SEM) and showed a tendency for grain sized reduction due to Nb addition. Moreover, the films were found to be very dense with no columnar microstructure. Structural analyses carried out by X-ray diffractometry (XRD) revealed that Nb introduces significant amount of defects in the crystal lattice which clearly degrade the optical properties.

  3. Near-infrared localized surface plasmon resonance of self-growing W-doped VO2 nanoparticles at room temperature

    Science.gov (United States)

    Nishikawa, Kazutaka; Kishida, Yoshihiro; Ito, Kota; Tamura, Shin-ichi; Takeda, Yasuhiko

    2017-11-01

    Nanoparticles (NPs) of vanadium dioxide (VO2) in the metal state exhibit localized surface plasmon resonance (LSPR) at 1200-1600 nm, which fills the gap between the absorption ranges of silicon and the LSPR of conventional transparent conductor NPs (ZnO:Al, In2O3:Sn, etc.). However, two issues of the lithographic process for NP formation and the metal-insulator transition temperature (69 °C) higher than room temperature have made it difficult to use VO2 NPs for applications such as energy conversion devices, near infrared (NIR) light detectors, and bio-therapy. In this study, we developed a self-growing process for tungsten (W)-doped VO2 NPs that are in the metal state at room temperature, using sputter deposition and post-lamp annealing. The changes in the LSPR peak wavelengths with the NP size were well controlled by changing the deposited film thickness and oxygen pressure during the post-annealing treatment. The presented results resolve the difficulties of using the metal-insulator transition material VO2 for practical NIR utilization.

  4. The ergogenic effect of recombinant human erythropoietin on VO2max depends on the severity of arterial hypoxemia

    DEFF Research Database (Denmark)

    Robach, Paul; Calbet, Jose A L; Thomsen, Jonas J

    2008-01-01

    Treatment with recombinant human erythropoietin (rhEpo) induces a rise in blood oxygen-carrying capacity (CaO(2)) that unequivocally enhances maximal oxygen uptake (VO(2)max) during exercise in normoxia, but not when exercise is carried out in severe acute hypoxia. This implies that there should ...

  5. Voltage- and current-activated metal–insulator transition in VO2-based electrical switches: a lifetime operation analysis

    Directory of Open Access Journals (Sweden)

    Aurelian Crunteanu, Julien Givernaud, Jonathan Leroy, David Mardivirin, Corinne Champeaux, Jean-Christophe Orlianges, Alain Catherinot and Pierre Blondy

    2010-01-01

    Full Text Available Vanadium dioxide is an intensively studied material that undergoes a temperature-induced metal–insulator phase transition accompanied by a large change in electrical resistivity. Electrical switches based on this material show promising properties in terms of speed and broadband operation. The exploration of the failure behavior and reliability of such devices is very important in view of their integration in practical electronic circuits. We performed systematic lifetime investigations of two-terminal switches based on the electrical activation of the metal–insulator transition in VO2 thin films. The devices were integrated in coplanar microwave waveguides (CPWs in series configuration. We detected the evolution of a 10 GHz microwave signal transmitted through the CPW, modulated by the activation of the VO2 switches in both voltage- and current-controlled modes. We demonstrated enhanced lifetime operation of current-controlled VO2-based switching (more than 260 million cycles without failure compared with the voltage-activated mode (breakdown at around 16 million activation cycles. The evolution of the electrical self-oscillations of a VO2-based switch induced in the current-operated mode is a subtle indicator of the material properties modification and can be used to monitor its behavior under various external stresses in sensor applications.

  6. Efeito da intensidade do exercício de corrida intermitente 30s:15s no tempo de manutenção no ou próximo do VO2max Effect of intensity of intermittent running exercise 30s:15s at the time maintenance at or near VO2max

    Directory of Open Access Journals (Sweden)

    Rafael Alves de Aguiar

    2013-03-01

    Full Text Available O presente estudo comparou o tempo mantido acima de 90% (t90VO2max e de 95% VO2max (t95VO2max em três diferentes intensidades de exercício. Após a realização de um teste incremental para determinar o VO2max, oito estudantes de educação física ativos (23 ± 3 anos executaram três sessões de exercícios intermitentes (100, 110 e 120% da velocidade do VO2max (vVO2max com razão esforço:recuperação de 30s:15s. O t95VO2max foi significantemente maior em 110%vVO2max (EI110% (218,1 ± 81,6 s quando comparado a 100%vVO2max (EI100% (91,9 ± 75,2s e a 120%vVO2max (EI120% (126,3 ± 29,4 s, porém sem diferença entre EI100% e EI120%. O t90VO2max somente apresentou diferença significante entre EI110% e EI120%. Portanto, conclui-se que durante exercício intermitente com razão 30s:15s, a intensidade de 110%vVO2max apresenta-se mais adequada para manter o VO2 próximo ou no VO2max por um tempo maior.The present study compared the time maintained above 90% (t90VO2max or 95% VO2max (t95VO2max in three different exercise intensities. After performing an incremental test to determine VO2max, eight physical education active students (23 ± 3 years performed three intermittent exercise sessions (100, 110 e 120% velocity of VO2max (vVO2max with ratio effort:recovery of 30s:15s. The t95%VO2max was significantly higher at 110%vVO2max (EI110% (218.1 ± 81.6s compared to 100% vVO2max (EI100% (91.9 ± 75.2s and 120%vVO2max (EI120% (126.3 ± 29.4s, but without differences between EI100% and EI120%. The t90%vVO2max was significantly different only between EI110% and 120%. Therefore, we conclude that during intermittent exercise with ratio 30s:15s, the intensity of 110%vVO2max appears more appropriate to maintain VO2max for a longer time.

  7. Effects of sprint interval training on VO2max and aerobic exercise performance: A systematic review and meta-analysis.

    Science.gov (United States)

    Sloth, M; Sloth, D; Overgaard, K; Dalgas, U

    2013-12-01

    Recently, several studies have examined whether low-volume sprint interval training (SIT) may improve aerobic and metabolic function. The objective of this study was to systematically review the existing literature regarding the aerobic and metabolic effects of SIT in healthy sedentary or recreationally active adults. A systematic literature search was performed (Bibliotek.dk, SPORTDiscus, Embase, PEDro, SveMed+, and Pubmed). Meta-analytical procedures were applied evaluating effects on maximal oxygen consumption (VO2max). Nineteen unique studies [four randomized controlled trials (RCTs), nine matched-controlled trials and six noncontrolled studies] were identified, evaluating SIT interventions lasting 2-8 weeks. Strong evidence support improvements of aerobic exercise performance and VO2max following SIT. A meta-analysis across 13 studies evaluating effects of SIT on VO2max showed a weighted mean effects size of g = 0.63 95% CI (0.39; 0.87) and VO2max increases of 4.2-13.4%. Solid evidence support peripheral adaptations known to increase the oxidative potential of the muscle following SIT, whereas evidence regarding central adaptations was limited and equivocal. Some evidence indicated changes in substrate oxidation at rest and during exercise as well as improved glycemic control and insulin sensitivity following SIT. In conclusion, strong evidence support improvement of aerobic exercise performance and VO2max following SIT, which coincides with peripheral muscular adaptations. Future RCTs on long-term SIT and underlying mechanisms are warranted. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. HIGHER PRECISION OF HEART RATE COMPARED WITH VO2 TO PREDICT EXERCISE INTENSITY IN ENDURANCE-TRAINED RUNNERS

    Directory of Open Access Journals (Sweden)

    Victor M. Reis

    2011-03-01

    Full Text Available The aim of the present study was to assess the precision of oxygen uptake with heart rate regression during track running in highly-trained runners. Twelve national and international level male long-distance road runners (age 30.7 ± 5.5 yrs, height 1.71 ± 0.04 m and mass 61.2 ± 5.8 kg with a personal best on the half marathon of 62 min 37 s ± 1 min 22 s participated in the study. Each participant performed, in an all-weather synthetic track five, six min bouts at constant velocity with each bout at an increased running velocity. The starting velocity was 3.33 m·s-1 with a 0.56 m·s-1 increase on each subsequent bout. VO2 and heart rate were measured during the runs and blood lactate was assessed immediately after each run. Mean peak VO2 and mean peak heart rate were, respectively, 76.2 ± 9.7 mL·kg-1·min-1 and 181 ± 13 beats·min-1. The linearity of the regressions between heart rate, running velocity and VO2 were all very high (r > 0.99 with small standard errors of regression (i.e. Sy.x < 5% at the velocity associated with the 2 and 4 mmol·L-1 lactate thresholds. The strong relationships between heart rate, running velocity and VO2 found in this study show that, in highly trained runners, it is possible to have heart rate as an accurate indicator of energy demand and of the running speed. Therefore, in this subject cohort it may be unnecessary to use VO2 to track changes in the subjects' running economy during training periods.

  9. Crystal structure and spectroscopic properties of Na2K6(VO)(2)(SO4)7

    DEFF Research Database (Denmark)

    Karydis, D.A.; Boghosian, S.; Nielsen, Kurt

    2002-01-01

    Red-brown crystals of a new mixed alkali oxo sulfato vanadium(V) compound Na2K6(VO)(2)(SO4)(7), suitable for X-ray determination, have been obtained from the catalytically important binary molten salt system M2S2O7-V2O5 (M = 80% K and 20% Na). By slow cooling of a mixture with the mole fraction X...... equatorial V-O bonds in the range 1.881(6)-1.960-(6) A. The deformation of the VO6 octahedron is less pronounced compared to that of the known oxo sulfato V(V) compounds. Each VO3+ group is coordinated to five sulfate groups of which two are unidentately coordinated and three are bidentate bridging...... to neighboring VO3+ groups. The length of the S-O bonds in the S-O-V bridges of the two unidentately coordinated sulfato groups are 1.551(6) Angstrom and 1.568(6) Angstrom, respectively, which are unusually long compared to our earlier measurements of sulfate groups in other V(111), V(IV), and V(V) compounds....

  10. Thermochromic VO2 thin films deposited by magnetron sputtering for smart window applications

    Science.gov (United States)

    Fortier, Jean-Philippe

    "Smart" windows are a perfect innovative example of technology that reduces our energy dependence and our impact on the environment while saving on the economical point of view. With the use of vanadium dioxide (VO2), a thermochromic compound, and this, as a thin coating, it would in fact be possible to control the sun's transmission of infrared light (heat) as a function of the surrounding environment temperature. In other words, its optical behavior would allow a more effective management of heat exchanges between a living venue and the outdoor environment. However, this type of window is still in a developmental stage. First, the oxide's deposition is not simple in nature. Based on a conventional deposition technique called magnetron sputtering mainly used in the fenestration industry, several factors such as the oxygen concentration and the substrate temperature during deposition can affect the coating's thermochromic behavior, and this, by changing its composition and crystallinity. Other control parameters such as the deposition rate, the pressure in the sputtering chamber and the choice of substrate may also modify the film microstructure, thereby varying its optical and electrical properties. In addition, several issues still persist as to its commercial application. For starters, the material's structural transition, related to the change of its optical properties, only occurs around 68°C. In addition, its low transparency and natural greenish colour are not visually appealing. Then, to this day, the deposition temperature required to crystallize and form the thermochromic oxide remains an obstacle for a possible large-scale application. Ultimately, although the material's change in temperature has been shown to be advantageous in situations of varying climate, the existing corrective solutions to these issues generate a deterioration of the thermochromic behavior. With no practical expertise on the material, this project was undertaken with certain

  11. Modeling of thermal coupling in VO2-based oscillatory neural networks

    Science.gov (United States)

    Velichko, Andrey; Belyaev, Maksim; Putrolaynen, Vadim; Perminov, Valentin; Pergament, Alexander

    2018-01-01

    In this study, we have demonstrated the possibility of using the thermal coupling to control the dynamics of operation of coupled VO2 oscillators. Based on the example of a 'switch-microheater' pair, we have explored the synchronization and dissynchronization modes of a single oscillator with respect to an external harmonic heat impact. The features of changes in the spectra are shown, in particular, the effect of the natural frequency attraction to the affecting signal frequency and the self-oscillation noise reduction effects at synchronization. The time constant of the temperature effect for the considered system configuration is in the range 7-140 μs, which allows operation in the oscillation frequency range of up to ∼70 kHz. A model estimate of the minimum temperature sensitivity of the switch is δTswitch ∼ 0.2 K, and the effective action radius RTC of the switch-to-switch thermal coupling is not less than 25 μm. Nevertheless, as the simulation shows, the frequency range can be significantly extended up to the values of 1-30 GHz if using nanometer-scale switches (heaters).

  12. Predicted VO2max and effectiveness of external chest compression by Chinese nurses.

    Science.gov (United States)

    Ho, Leo S T; Jones, Alice Y M; Rainer, Timothy H

    2017-08-01

    The aims of this study were to assess the influence of sex and body position on external chest compression (ECC) to a manikin by Chinese nurses and to determine the relationship between rescuer's predicted VO2max and ECC depth. A total of 40 nurses performed ECC on a manikin for 5 min in the standing (S) and bed-mount kneeling (K) position, then completed a Chester step-test, in 3 separate days. The rate and depth of compressions and oxygen consumption during ECC were measured. Mean compression rate recorded was above 100/min in both positions throughout ECC. Mean compression depth for male participants was more than 38 mm for 5 min in the K-position but only 3 min in the S-position. Female participants achieved this compression depth for less than 90 s in the K-position but not at all in the S-position. Irrespective of sex, the K-position appears to facilitate effective ECC. The relationship between aerobic fitness of female nurses and their ability to perform effective cardiopulmonary resuscitation warrants further investigation.

  13. Ultrafast nano-imagining of the photoinduced phase transition dynamics in VO2

    Science.gov (United States)

    Doenges, Sven A.; Khatib, Omar; O'Callahan, Brian T.; Atkin, Joanna M.; Park, Jae Hyung; Cobden, David H.; Raschke, Markus B.

    Many quantum phase transitions in correlated matter exhibit spatial inhomogeneities with expected yet unexplored effects on the associated ultrafast dynamics. Here we demonstrate the combination of ultrafast non-degenerate pump-probe spectroscopy with scattering scanning near-field optical microscopy (s-SNOM) for ultrafast nano-imaging. In a femtosecond near-field non-degenerate near-IR (NIR) pump and mid-IR (MIR) probe experiment, we study the photoinduced insulator-to-metal (IMT) transition in nominally homogeneous VO2 micro-crystals using far-from equilibrium excitation. We observe spatial heterogeneity on 50-100 nm length scales in the fluence dependent IMT dynamics, ranging from sub-100 fs to 1 ps. With pump fluences as high as nominally 10 mJ/cm2 we can reach distinct excitation and saturation regimes. These results suggest a large sensitivity of the IMT with respect to local variations in strain, doping, or defects difficult to discern microscopically.

  14. The effects of an acute bout of sleep on running economy and VO2 max.

    Science.gov (United States)

    Pierce, E F; McGowan, R W; Barkett, E; Fry, R W

    1993-04-01

    Synchronized human sleep has been shown to decrease activation of the sympathetic nervous system, resulting in reduced levels of oxygen consumption. This is in direct conflict with sympathetic arousal, which coincides with the initiation of exercise. Although a considerable body of research has investigated the effects of sleep deprivation on exercise performance, the effects of an acute bout of sleep on exercise response have not been previously reported. This question appears relevant considering the occurrence of acute sleep bouts among athletes competing in prolonged multi-event competition (e.g. swimming, track and field). To investigate the effects of an acute bout of sleep on submaximal (running economy) and maximal oxygen consumption, seven male volunteers participated in a continuous, progressive treadmill test to volitional exhaustion immediately following a 1-h bout of sleep (SB) or no sleep (Control). The subjects served as their own controls and the order of trials was randomized. A MANOVA with repeated measures indicated no difference between groups for running economy or VO2 (P sleep.

  15. Bedrest-induced peak VO2 reduction associated with age, gender, and aerobic capacity

    Science.gov (United States)

    Convertino, V. A.; Goldwater, D. J.; Sandler, H.

    1986-01-01

    A study measuring the peak oxygen uptake (V02), heart rate (HR), and exercise tolerance time of 15 men of 55 + or - 2 yr and 17 women of 55 + or - 1 yr after 10 days of continuous bed rest (BR) is presented. The experimental conditions and procedures are described. Following BR a decrease in peak VO2 of 8.4 percent in men and 6.8 percent in women, a reduction in exercise tolerance time by 8.1 percent in men and 7.3 percent in women, and an increse in HR of 4.4 percent and 1.3 percent for men and women, respectively, are observed. These data are compared with data from Convertino et al. (1977) for men 21 + or - 1 yr and women 28 + or - 2yr. It is concluded that BR-induced aerobic deconditioning is independent of age and sex, since the relative decrease in peak V02 in the older and younger subjects and men and women are similar.

  16. Aerobic Fitness Levels and Validation of a Non-Exercise VO2max Prediction Equation for HIV-Infected Patients on HAART

    Science.gov (United States)

    Sullivan, Katherine; Shikuma, Cecilia M.; Chow, Dominic; Cornelius, Elizabeth; Romine, Rebecca K.; Lindsey, Rachel A.; Stickley, Christopher D.; Kimura, Iris F.; Hetzler, Ronald K.

    2015-01-01

    Background Non-exercise (N-EX) questionnaires have been developed to determine maximal oxygen consumption (VO2max) in healthy populations. There are limited reliable and validated N-EX questionnaires for the HIV+ population that provide estimates of habitual physical activity and not VO2max. Objectives To determine how well regression equations developed previously on healthy populations, including N-EX prediction equations for VO2max and age-predicted maximal heart rates (APMHR), worked on an HIV+ population; and to develop a specific N-EX prediction equation for VO2max and APMHR for HIV+ individuals. Methods Sixty-six HIV+ participants on stable HAART completed 4 N-EX questionnaires and performed a maximal graded exercise test. Results Sixty males and 6 females were included; mean (SD) age was 49.2 (8.2) years; CD4 count was 516.0 ± 253.0 cells·mn−3; and 92% had undetectable HIV PCR. Mean VO2max was 29.2 ± 7.6 (range, 14.4–49.4) mL·kg−1·min−1. Despite positive correlations with VO2max, previously published N-EX VO2max equations produced results significantly different than actual VO2 scores (P VO2max values, R = 0.71, when compared to achieved VO2max (P = .53). Conclusion HIV+ individuals tend to be sedentary and unfit, putting them at increased risk for the development of chronic diseases associated with a sedentary lifestyle. Based on the level of error associated with utilizing APMHR and N-EX VO2max equations with HIV+ individuals, neither should be used in this population for exercise prescription. PMID:24710921

  17. Aerobic fitness levels and validation of a non exercise VO2max prediction equation for HIV-infected patients on HAART.

    Science.gov (United States)

    Sullivan, Katherine; Shikuma, Cecilia M; Chow, Dominic; Cornelius, Elizabeth; Romine, Rebecca K; Lindsey, Rachel A; Stickley, Christopher D; Kimura, Iris F; Hetzler, Ronald K

    2014-01-01

    Non-exercise (N-EX) questionnaires have been developed to determine maximal oxygen consumption (VO2max) in healthy populations. There are limited reliable and validated N-EX questionnaires for the HIV+ population that provide estimates of habitual physical activity and not VO2max. To determine how well regression equations developed previously on healthy populations, including N-EX prediction equations for VO2max and age-predicted maximal heart rates (APMHR), worked on an HIV+ population; and to develop a specific N-EX prediction equation for VO2max and APMHR for HIV+ individuals. Sixty-six HIV+ participants on stable HAART completed 4 N-EX questionnaires and performed a maximal graded exercise test. Sixty males and 6 females were included; mean (SD) age was 49.2 (8.2) years; CD4 count was 516.0 ± 253.0 cells·mm-3; and 92% had undetectable HIV PCR. Mean VO2max was 29.2 ± 7.6 (range, 14.4-49.4) mL·kg-1·min-1 Despite positive correlations with VO2max, previously published N-EX VO2max equations produced results significantly different than actual VO2 scores (P population for exercise prescription.

  18. Changes in Running Economy, Respiratory Exchange Ratio and VO2max in Runners following a 10-day Altitude Training Camp.

    Science.gov (United States)

    Diebel, Sebastian R; Newhouse, Ian; Thompson, David S; Johnson, Vineet B K

    2017-01-01

    Running economy (RE) and VO2max are important predictors of endurance performance for elite and semi-elite endurance athletes, with RE being an appropriate predictor in a homogenous running population. Altitude training has been observed to change RE (mL.kg-1.min-1), and VO2max due to alterations resulting from acclimatization. This study tracked changes in RE and VO2max before and after a 10-day altitude training camp at 1828 meters. VO2max, RE expressed calorically, and respiratory exchange ratio (RER), were measured below anaerobic threshold (AT) to observe differences between pre-and post-altitude training. Eight varsity cross-country runners between the ages of 18 and 22 years performed an incremental treadmill test, pre- and post-10-day altitude training. Paired samples t-tests were used to statistically analyze the data. Average RE (VO2 mL.kg-1.min-1) improved following altitude intervention (M= 56.44 ± 4.28) compared to pre-altitude training (61.30 ± 7.56). These differences were statistically significant t(7)= 2.71, p =.014. RE expressed as kcals.kg-1.km-1 improved following altitude training (16.73 ± 2.96) compared to (18.44 ± 4.04) pre-altitude training and was statistically significant t(7) =3.08, p = .008. RER taken during the last minute of steady-state was higher (0.97, ± .019) post-altitude training, compared to (0.90 ± .043) pre-altitude. These differences were statistically significant t(7) -3.62, p =.008. VO2max (mL.kg-1.min-1) was lower in 6 out of 8 participants (63.91, ± 8.65) post-altitude compared to (69.90, ± 10.80) pre-altitude and was statistically significant t(7) = 2.33, p =.026. The observed improvements in RE may be beneficial for endurance athletes competing and/or training at moderate altitudes near 1828 meters.

  19. Plasma volume expansion does not increase maximal cardiac output or VO2 max in lowlanders acclimatized to altitude

    DEFF Research Database (Denmark)

    Calbet, José A L; Rådegran, Göran; Boushel, Robert Christopher

    2004-01-01

    liter of 6% dextran 70 (BV = 6.32 +/- 0.34 liters). PV expansion had no effect on Qmax, maximal O2 consumption (VO2), and exercise capacity. Despite maximal systemic O2 transport being reduced 19% due to hemodilution after PV expansion, whole body VO2 was maintained by greater systemic O2 extraction (P...... level Qmax and exercise capacity were restored with hyperoxia at altitude independently of BV. Low BV is not a primary cause for reduction of Qmax at altitude when acclimatized. Furthermore, hemodilution caused by PV expansion at altitude is compensated for by increased systemic O2 extraction...... with similar peak muscular O2 delivery, such that maximal exercise capacity is unaffected....

  20. VO2 Thermochromic Films on Quartz Glass Substrate Grown by RF-Plasma-Assisted Oxide Molecular Beam Epitaxy

    Directory of Open Access Journals (Sweden)

    Dong Zhang

    2017-03-01

    Full Text Available Vanadium dioxide (VO2 thermochromic thin films with various thicknesses were grown on quartz glass substrates by radio frequency (RF-plasma assisted oxide molecular beam epitaxy (O-MBE. The crystal structure, morphology and chemical stoichiometry were investigated systemically by X-ray diffraction (XRD, atomic force microscopy (AFM, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS analyses. An excellent reversible metal-to-insulator transition (MIT characteristics accompanied by an abrupt change in both electrical resistivity and optical infrared (IR transmittance was observed from the optimized sample. Remarkably, the transition temperature (TMIT deduced from the resistivity-temperature curve was reasonably consistent with that obtained from the temperature-dependent IR transmittance. Based on Raman measurement and XPS analyses, the observations were interpreted in terms of residual stresses and chemical stoichiometry. This achievement will be of great benefit for practical application of VO2-based smart windows.

  1. Dynamically tracking the joule heating effect on the voltage induced metal-insulator transition in VO2 crystal film

    Directory of Open Access Journals (Sweden)

    G. M. Liao

    2016-04-01

    Full Text Available Insulator to metal phase transitions driven by external electric field are one of the hottest topics in correlated oxide study. While this electric triggered phenomena always mixes the electric field switching effect and joule thermal effect together, which are difficult to clarify the intrinsic mechanism. In this paper, we investigate the dynamical process of voltage-triggered metal-insulator transition (MIT in a VO2 crystal film and observe the temperature dependence of the threshold voltages and switching delay times, which can be explained quite well based on a straightforward joule thermal model. By conducting the voltage controlled infrared transmittance measurement, the delayed infrared transmission change is also observed, further confirming the homogeneous switching process for a large-size film. All of these results show strong evidences that joule thermal effect plays a dominated role in electric-field-induced switching of VO2 crystal.

  2. The electro-optic mechanism and infrared switching dynamic of the hybrid multilayer VO2/Al:ZnO heterojunctions

    OpenAIRE

    Zhang, Peng; Zhang, Wu; Wang, Junyong; Jiang, Kai; Zhang, Jinzhong; Li, Wenwu; Wu, Jiada; Hu, Zhigao; Chu, Junhao

    2017-01-01

    Active and widely controllable phase transition optical materials have got rapid applications in energy-efficient electronic devices, field of meta-devices and so on. Here, we report the optical properties of the vanadium dioxide (VO2)/aluminum-doped zinc oxide (Al:ZnO) hybrid n-n type heterojunctions and the corresponding electro-optic performances of the devices. Various structures are fabricated to compare the discrepancy of the optical and electrical characteristics. It was found that the...

  3. Ramp-incremented and RPE-clamped test protocols elicit similar VO2max values in trained cyclists.

    Science.gov (United States)

    Straub, Allison M; Midgley, Adrian W; Zavorsky, Gerald S; Hillman, Angela R

    2014-08-01

    The present study compared the efficacy of ramp incremented and ratings of perceived exertion (RPE)-clamped test protocols for eliciting maximal oxygen uptake (VO2max). Sixteen trained cyclists (age 34 ± 7 years) performed a ramp-incremented protocol and an RPE-clamped protocol 1 week apart in a randomized, counterbalanced order. The RPE-clamped protocol consisted of five, 2-min stages where subjects self-selected work rate and pedal cadence to maintain the prescribed RPE. After completing both test protocols subjects were asked which they preferred. The mean ± SD test time of 568 ± 72 s in the ramp protocol was not significantly different to the 600 ± 0 s in the RPE-clamped protocol (mean difference = 32 s; p = 0.09), or was the VO2max of 3.86 ± 0.73 L min(-1) in the ramp protocol significantly different to the 3.87 ± 0.72 L min(-1) in the RPE-clamped protocol (mean difference = 0.002 L min(-1); p = 0.97). Furthermore, no significant differences were observed for peak power output (p = 0.21), maximal minute ventilation (p = 0.97), maximal respiratory exchange ratio (p = 0.09), maximal heart rate (p = 0.51), and post-test blood lactate concentration (p = 0.58). The VO2max attained in the preferred protocol was significantly higher than the non-preferred protocol (mean difference = 0.14 L min(-1); p = 0.03). The RPE-clamped test protocol was as effective as the ramp-incremented protocol for eliciting VO2max and could be considered as a valid alternative protocol, particularly where a fixed test duration is desirable.

  4. Evaluation of cardiorespiratory fitness using three field tests in obese adolescents: validity, sensitivity and prediction of peak VO2.

    Science.gov (United States)

    Quinart, Sylvain; Mougin, Fabienne; Simon-Rigaud, Marie-Laure; Nicolet-Guénat, Marie; Nègre, Véronique; Regnard, Jacques

    2014-09-01

    Evaluation of cardiorespiratory fitness in obese adolescents is necessary to develop personalised retraining programmes. We aimed to measure cardiorespiratory fitness using 3 field tests, and to evaluate their validity and sensitivity compared to values obtained by laboratory tests. Longitudinal interventional study in obese adolescents admitted to a rehabilitation centre for a 9-month programme of obesity management. A 12-min walk/run test, an adapted 20 m shuttle walk-run test (starting speed 4 km h(-1), increments of 0.5 km h(-1)min(-1)) and a 4-level submaximal cycle ergometer test were performed to estimate respectively distance covered in 12 min, maximum speed and maximal aerobic power. Thirty adolescents aged 14.2 ± 1.6 years were included. After 9 months intervention, we observed a significant reduction in body mass index, and an increase in peak VO2 and field test results. We observed significant correlations between pre- and post-intervention values of peak VO2 and distance covered in 12 min (r=0.70 pre; r=0.82 post), maximum speed (r=0.80 pre; r=0.83 post) and maximal aerobic power (r=0.71 pre; r=0.84 post). Multiple linear regression made it possible to estimate peak VO2 based on results from the 3 field tests using prediction equations specific to a population of obese adolescents. These field tests, including the adapted 20 m shuttle walk-run test, adequately assess cardiorespiratory fitness in obese adolescents, and are sensitive to changes over time. Predictive equations including BMI are useful in clinical practice to predict peak VO2 in these patients. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  5. Block training periodization in alpine skiing: effects of 11-day HIT on VO2max and performance.

    Science.gov (United States)

    Breil, Fabio A; Weber, Simone N; Koller, Stefan; Hoppeler, Hans; Vogt, Michael

    2010-08-01

    Attempting to achieve the high diversity of training goals in modern competitive alpine skiing simultaneously can be difficult and may lead to compromised overall adaptation. Therefore, we investigated the effect of block training periodization on maximal oxygen consumption (VO2max) and parameters of exercise performance in elite junior alpine skiers. Six female and 15 male athletes were assigned to high-intensity interval (IT, N = 13) or control training groups (CT, N = 8). IT performed 15 high-intensity aerobic interval (HIT) sessions in 11 days. Sessions were 4 x 4 min at 90-95% of maximal heart rate separated by 3-min recovery periods. CT continued their conventionally mixed training, containing endurance and strength sessions. Before and 7 days after training, subjects performed a ramp incremental test followed by a high-intensity time-to-exhaustion (tlim) test both on a cycle ergometer, a 90-s high-box jump test as well as countermovement (CMJ) and squat jumps (SJ) on a force plate. IT significantly improved relative VO2max by 6.0% (P power output by 5.5% (P power output at ventilatory threshold 2 by 9.6% (P power (CMJ -4.8%, SJ -4.1%; P < 0.01), but not height decreased in IT only. For competitive alpine skiers, block periodization of HIT offers a promising way to efficiently improve VO2max and performance. Compromised explosive jump performance might be associated with persisting muscle fatigue.

  6. Development of non-exercise based VO2max prediction equation in college-aged participants in India.

    Science.gov (United States)

    Shenoy, S; Tyagi, B; Sandhu, J; Sengupta, D

    2012-10-01

    The purpose of this study was to develop a linear regression model to predict treadmill VO2max scores using non-exercise data. In this cross sectional study, one hundred twenty college-aged participants (60 male, 60 female, mean age 22.02±2.29 years) voluntarily participated and successfully completed a maximal graded exercise test (GXT) on a motorized treadmill to assess VO2max (mean±SD; 2.05 L·min-¹±1.03 L·min-¹). The maximal treadmill GXT required participants to exercise to volitional fatigue. Relevant non-exercise data included a mean (±SD) perceived functional ability (PFA) score, and physical activity rating (PA-R) score, body surface area (BSA) of 14.6±3.9, 2.97±1..75, 1.66±0.17, respectively. Multiple linear regression generated the following regression equation (R=0.899, R2=0.805, adjusted R2=0.799, SEE=0.426 L·min-¹): VO2max (L/min)=-1.541+1.096 (gender, 1=male, 0=female) +.081 (PFA) +1.084(BSA). Each predictor variable was statistically significant (PVO2max in healthy college-aged participants in India.

  7. Highly transparent VO2-SiO2 films with excellent infrared characteristics by dual-target magnetron sputtering

    Science.gov (United States)

    Cheng, Qing; Su, Da; Wang, Yaqin; Huang, Ying

    2017-08-01

    With the aim to fabricate high quality and boosting the optical performance of vanadium dioxide (VO2) film, basing on effective medium theory, dual-target magnetron sputtering method is first introduced into VO2-SiO2 composite film on quartz by changing the flow ratio of Argon and oxygen. X-Ray diffraction measurement indicates the purity of the composite film. Atomic force microscopy measurement shows that the minimum grain size is about 45nm. Infrared (IR) switching characteristic is well demonstrated by a double-frequented He-Ne laser at the wavelength of 3mμ,compare to VO2 film obtained at the same sputtering time, the result reveals that the composite film exhibit excellent IR switching property, furthermore, multi-wavelength tests and calculations show that all of the obtained composite films exhibit high integrate luminous transmittance of 50%, and the transmittance in semiconducting phase of one thin film is 65% and decreases to 24% in metallic phase at the wavelength of 2mμ , with the switching efficiency of 63%. High visible transmittance and excellent infrared switching characteristics make the film an appropriate candidate for laser protection as well as smart windows.

  8. Anti-biofouling function of amorphous nano-Ta2O5 coating for VO2-based intelligent windows

    Science.gov (United States)

    Li, Jinhua; Guo, Geyong; Wang, Jiaxing; Zhou, Huaijuan; Shen, Hao; Yeung, Kelvin W. K.

    2017-04-01

    From environmental and health perspectives, the acquisition of a surface anti-biofouling property holds important significance for the usability of VO2 intelligent windows. Herein, we firstly deposited amorphous Ta2O5 nanoparticles on VO2 film by the magnetron sputtering method. It was found that the amorphous nano-Ta2O5 coating possessed a favorable anti-biofouling capability against Pseudomonas aeruginosa as an environmental microorganism model, behind which lay the mechanism that the amorphous nano-Ta2O5 could interrupt the microbial membrane electron transport chain and significantly elevate the intracellular reactive oxygen species (ROS) level. A plausible relationship was established between the anti-biofouling activity and physicochemical nature of amorphous Ta2O5 nanoparticles from the perspective of defect chemistry. ROS-induced oxidative damage gave rise to microbial viability loss. In addition, the amorphous nano-Ta2O5 coating can endow VO2 with favorable cytocompatibility with human skin fibroblasts. This study may provide new insights into understanding the anti-biofouling and antimicrobial actions of amorphous transition metal oxide nanoparticles, which is conducive to expanding their potential applications in environmental fields.

  9. Tracking the insulator-to-metal phase transition in VO2 with few-femtosecond extreme UV transient absorption spectroscopy.

    Science.gov (United States)

    Jager, Marieke F; Ott, Christian; Kraus, Peter M; Kaplan, Christopher J; Pouse, Winston; Marvel, Robert E; Haglund, Richard F; Neumark, Daniel M; Leone, Stephen R

    2017-09-05

    Coulomb correlations can manifest in exotic properties in solids, but how these properties can be accessed and ultimately manipulated in real time is not well understood. The insulator-to-metal phase transition in vanadium dioxide (VO2) is a canonical example of such correlations. Here, few-femtosecond extreme UV transient absorption spectroscopy (FXTAS) at the vanadium M2,3 edge is used to track the insulator-to-metal phase transition in VO2 This technique allows observation of the bulk material in real time, follows the photoexcitation process in both the insulating and metallic phases, probes the subsequent relaxation in the metallic phase, and measures the phase-transition dynamics in the insulating phase. An understanding of the VO2 absorption spectrum in the extreme UV is developed using atomic cluster model calculations, revealing V3+/d2 character of the vanadium center. We find that the insulator-to-metal phase transition occurs on a timescale of 26 ± 6 fs and leaves the system in a long-lived excited state of the metallic phase, driven by a change in orbital occupation. Potential interpretations based on electronic screening effects and lattice dynamics are discussed. A Mott-Hubbard-type mechanism is favored, as the observed timescales and d2 nature of the vanadium metal centers are inconsistent with a Peierls driving force. The findings provide a combined experimental and theoretical roadmap for using time-resolved extreme UV spectroscopy to investigate nonequilibrium dynamics in strongly correlated materials.

  10. Characterization of thermochromic VO2 (prepared at 250 °C) in a wide temperature range by spectroscopic ellipsometry

    Science.gov (United States)

    Houska, J.; Kolenaty, D.; Rezek, J.; Vlcek, J.

    2017-11-01

    The paper deals with thermochromic VO2 prepared by reactive high-power impulse magnetron sputtering and characterized by spectroscopic ellipsometry. We focus on the dispersion of optical constants in a wide temperature range and on the transmittance predicted using the optical constants. While the thermochromic behavior of VO2 in itself has been reported previously (particularly above the room temperature, RT), in this paper we present (i) optical properties achieved at a low deposition temperature of 250 °C and without any substrate bias voltage (which dramatically increases the application potential of the coating) and (ii) changes of these properties not only above but also below RT (down to -30 °C). The properties include very low (for VO2) extinction coefficient at RT (0.10 at 550 nm), low transition temperature of around or even below 50 °C (compared to the frequently cited 68 °C) and high modulation of the predicted infrared transmittance (e.g. 39% at -30 °C, 30% at RT and 3.4% above the transition temperature at 2000 nm for a 100 nm thick coating on glass). The results are important for the design of thermochromic coatings, and pathways for their preparation under industry-friendly conditions, for various technological applications.

  11. The effect of a peer on VO2 and game choice in 6-10 year old children

    Directory of Open Access Journals (Sweden)

    Lee Anne Siegmund

    2014-06-01

    Full Text Available Relative to sedentary video games (e.g., Playstation 2 (PS2, playing physically active video games (e.g., Nintendo Wii (Wii significantly increases caloric expenditure in children. Studies have demonstrated that the presence of a peer increases physical activity in children. We sought to determine if children would expend more energy and find playing Wii more motivating than PS2 when with a peer. Seventeen children (age 8.5 ± 0.4 years rested, played PS2 and Wii Sports Boxing for 10 minutes each, in two conditions: one in which the children rested/played the games alone (alone condition and another in which they played with a peer (peer condition. Oxygen consumption (VO2, and liking (visual analog scale was assessed for each 10-minute condition. After three 10-minute resting/gaming conditions, motivation was assessed using a relative reinforcing value task (RRV in which children performed computer mouse presses to gain additional access for either PS2 or Wii. VO2 was greater (p Conclusion: The presence of a peer increased VO2 during Wii play for boys but not girls. Surprisingly, the presence of a peer decreased children’s motivation to play Wii versus PS2.

  12. Tracking the insulator-to-metal phase transition in VO2 with few-femtosecond extreme UV transient absorption spectroscopy

    Science.gov (United States)

    Jager, Marieke F.; Ott, Christian; Kraus, Peter M.; Kaplan, Christopher J.; Pouse, Winston; Marvel, Robert E.; Haglund, Richard F.; Neumark, Daniel M.; Leone, Stephen R.

    2017-09-01

    Coulomb correlations can manifest in exotic properties in solids, but how these properties can be accessed and ultimately manipulated in real time is not well understood. The insulator-to-metal phase transition in vanadium dioxide (VO2) is a canonical example of such correlations. Here, few-femtosecond extreme UV transient absorption spectroscopy (FXTAS) at the vanadium M2,3 edge is used to track the insulator-to-metal phase transition in VO2. This technique allows observation of the bulk material in real time, follows the photoexcitation process in both the insulating and metallic phases, probes the subsequent relaxation in the metallic phase, and measures the phase-transition dynamics in the insulating phase. An understanding of the VO2 absorption spectrum in the extreme UV is developed using atomic cluster model calculations, revealing V3+/d2 character of the vanadium center. We find that the insulator-to-metal phase transition occurs on a timescale of 26 ± 6 fs and leaves the system in a long-lived excited state of the metallic phase, driven by a change in orbital occupation. Potential interpretations based on electronic screening effects and lattice dynamics are discussed. A Mott-Hubbard-type mechanism is favored, as the observed timescales and d2 nature of the vanadium metal centers are inconsistent with a Peierls driving force. The findings provide a combined experimental and theoretical roadmap for using time-resolved extreme UV spectroscopy to investigate nonequilibrium dynamics in strongly correlated materials.

  13. The effect of Argon pressure dependent V thin film on the phase transition process of (020) VO2 thin film

    Science.gov (United States)

    Meng, Yifan; Huang, Kang; Tang, Zhou; Xu, Xiaofeng; Tan, Zhiyong; Liu, Qian; Wang, Chunrui; Wu, Binhe; Wang, Chang; Cao, Juncheng

    2018-01-01

    It has been proved challenging to fabricate the single crystal orientation of VO2 thin film by a simple method. Based on chemical reaction thermodynamic and crystallization analysis theory, combined with our experimental results, we find out that when stoichiometric number of metallic V in the chemical equation is the same, the ratio of metallic V thin film surface average roughness Ra to thin film average particle diameter d decreases with the decreasing sputtering Argon pressure. Meanwhile, the oxidation reaction equilibrium constant K also decreases, which will lead to the increases of oxidation time, thereby the crystal orientation of the VO2 thin film will also become more uniform. By sputtering oxidation coupling method, metallic V thin film is deposited on c-sapphire substrate at 1 × 10-1 Pa, and then oxidized in the air with the maximum oxidation time of 65s, high oriented (020) VO2 thin film has been fabricated successfully, which exhibits ∼4.6 orders sheet resistance change across the metal-insulator transition.

  14. Preparation, Characterization and Thermo-Chromic Properties of EVA/VO2 Laminate Films for Smart Window Applications and Energy Efficiency in Building

    Directory of Open Access Journals (Sweden)

    Onruthai Srirodpai

    2017-01-01

    Full Text Available Thermochromic films based on vanadium dioxide (VO2/ethylene vinyl acetate copolymer (EVA composite were developed. The monoclinic VO2 particles was firstly prepared via hydrothermal and calcination processes. The effects of hydrothermal time and tungsten doping agent on crystal structure and morphology of the calcined metal oxides were reported. After that, 1 wt % of the prepared VO2 powder was mixed with EVA compound, using two different mixing processes. It was found that mechanical properties of the EVA/VO2 films prepared by the melt process were superior to those of which prepared by the solution process. On the other hand, percentage visible light transmittance of the solution casted EVA/VO2 film was greater than that of the melt processed composite film. This was related to the different gel content of EVA rubber and state of dispersion and distribution of VO2 within the polymer matrix phase. Thermochromic behaviors and heat reflectance of the EVA/VO2 film were also verified. In overall, this study demonstrated that it was possible to develop a thermochromic film using the polymer composite approach. In this regard, the mixing condition was found to be one of the most important factors affecting morphology and thermo-mechanical properties of the films.

  15. Tuning of thermally induced first-order semiconductor-to-metal transition in pulsed laser deposited VO2 epitaxial thin films

    Science.gov (United States)

    Behera, Makhes K.; Pradhan, Dhiren K.; Pradhan, Sangram K.; Pradhan, Aswini K.

    2017-12-01

    Vanadium oxide (VO2) thin films have drawn significant research and development interest in recent years because of their intriguing physical origin and wide range of functionalities useful for many potential applications, including infrared imaging, smart windows, and energy and information technologies. However, the growth of highly epitaxial films of VO2, with a sharp and distinct controllable transition, has remained a challenge. Here, we report the structural and electronic properties of high quality and reproducible epitaxial thin films of VO2, grown on c-axis oriented sapphire substrates using pulsed laser deposition at different deposition pressures and temperatures, followed by various annealing schedules. Our results demonstrate that the annealing of epitaxial VO2 films significantly enhances the Semiconductor to Metal Transition (SMT) to that of bulk VO2 transition. The effect of oxygen partial pressure during the growth of VO2 films creates a significant modulation of the SMT from around room temperature to as high as the theoretical value of 68 °C. We obtained a bulk order transition ≥104 while reducing the transition temperature close to 60 °C, which is comparatively less than the theoretical value of 68 °C, demonstrating a clear and drastic improvement in the SMT switching characteristics. The results reported here will open the door to fundamental studies of VO2, along with tuning of the transition temperatures for potential applications for multifunctional devices.

  16. The Effects of Vanadium Pentoxide to Oxalic Acid Ratio and Different Atmospheres on the Formation of VO2 Nanopowders Synthesized via Sol-Gel Method

    Science.gov (United States)

    Vostakola, Mohsen Fallah; Yekta, Bijan Eftekhari; Mirkazemi, Seyed Mohammad

    2017-11-01

    Thermochromic VO2 nanopowders were synthesized via the sol-gel method through mixing oxalic acid and vanadium pentoxide in ethanol. We investigated the effect of oxalic acid to vanadium pentoxide ratio on the formation of final product and found that excessive oxalic acid reduced the final product from VO2 to V2O3. Because decreasing the oxalic acid to vanadium pentoxide ratio is a time-consuming process, oxygen was introduced by using a low-porosity alumina tube. The heat treatment was performed inside an electrical tube furnace and in a variety of atmospheres, including pure nitrogen (99.999% purity) and nitrogen containing 5 vol.%, 10 vol.%, and 15 vol.% hydrogen. According to x-ray diffraction (XRD) results, the appropriate atmosphere for synthesizing VO2 nanopowder was the one which contained 10 vol.% hydrogen. In order to decrease the transition temperature in VO2 from 63.5°C to room temperature, W6+ doping was done by adding different amounts of tungstic acid sol to vanadium sol precursor. Differential scanning calorimetry (DSC) results showed that W6+ reduced the transition temperature of VO2 approximately 23°C/wt.%. Lattice straining estimated from XRD results confirmed that VO2 was doped. XRD results at 25°C and 100°C along with DSC results indicated that VO2 was transformed from a low-temperature monoclinic phase to a high-temperature rutile one along this temperature interval.

  17. The visible transmittance and solar modulation ability of VO2 flexible foils simultaneously improved by Ti doping: an optimization and first principle study.

    Science.gov (United States)

    Chen, Shi; Dai, Lei; Liu, Jianjun; Gao, Yanfeng; Liu, Xinling; Chen, Zhang; Zhou, Jiadong; Cao, Chuanxiang; Han, Penggang; Luo, Hongjie; Kanahira, Minoru

    2013-10-28

    The Mott phase transition compound vanadium dioxide (VO2) shows promise as a thermochromic smart material for the improvement of energy efficiency and comfort in a number of applications. However, the use of VO2 has been restricted by its low visible transmittance (Tvis) and limited solar modulation ability (ΔTsol). Many efforts have been made to improve both of these limitations, but progress towards the optimization of one aspect has always come at the expense of the other. This paper reports that Ti doping results in the improvement of both the Tvis and ΔTsol of VO2-nanoparticle-derived flexible foils to the best levels yet reported. Compared with an undoped VO2 foil, a 15% increase (from 46.1% to 53%) in Tvis and a 28% increase (from 13.4% to 17.2%) in ΔTsol are achieved at a Ti doping level of 1.1%, representing the best performance reported for similar foils or films prepared using various methods. Only a defined doping level of less than 3% is beneficial for simultaneous improvement in Tvis and ΔTsol. First principle calculations suggest that an increase in the intrinsic band gap of VO2 (M) and the reduced electron density at Fermi level of VO2 (R) cooperate to result in the improvement of ΔTsol and that an enhancement in the optical band gap of VO2 (M) leads to the increase of Tvis.

  18. Coherent control of optical absorption and the energy transfer pathway of an infrared quantum dot hybridized with a VO2 nanoparticle

    Science.gov (United States)

    Hatef, Ali; Zamani, Naser; Johnston, William

    2017-04-01

    We systematically investigate the optical response of a semiconductor quantum dot (QD) hybridized with a vanadium dioxide nanoparticle (VO2NP) in the infrared (IR) region. The VO2NP features a semiconductor to metal phase change characteristic below and above a critical temperature that leads to an abrupt change in the particle’s optical properties. This feature means that the QD-VO2NP hybrid system can support the coherent coupling of exciton-polaritons and exciton-plasmon polaritons in the semiconductor and metal phases of the VO2NP, respectively. In our calculations, the VO2NP phase transition is modelled with a filling fraction (f), representing the fraction of the VO2NP in the metallic phase. The phase transition is driven by the hybrid system’s interaction with a continuous wave (CW) IR laser field. In this paper, we show how control over the filling fraction results in the enhancement or suppression of the QD’s linear absorption. These variations in the QD absorption is due to dramatic changes in the effective local field experienced by the QD and the non-radiative energy transfer from the QD to the VO2NP. The presented results have the potential to be applied to the design of thermal sensors at the nanoscale.

  19. Surface engineering on continuous VO2 thin films to improve thermochromic properties: Top-down acid etching and bottom-up self-patterning.

    Science.gov (United States)

    Wang, Ning; Peh, Yew Keat; Magdassi, Shlomo; Long, Yi

    2018-02-15

    Surface engineering is an effective method to improve the thermochromic performance of VO2. In this paper, an acid-etching top down method was proposed to tailor the VO2 surface morphology from the continuous dense-packed surface to patterned structure, which exhibited the enhanced integrated visible transmittance (Tlum) and the enlarged solar modulating abilities (ΔTsol). Moreover, a self-patterning approach was also illustrated to improve the thermochromic properties. The proposed surface engineering methods represent a facile and cost-effective approach for enhancing thermochromic properties that could promote the application of VO2 thin films in smart windows. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Efeito da intensidade do exercício de corrida intermitente 30s:15s no tempo de manutenção no ou próximo do VO2max

    OpenAIRE

    Aguiar,Rafael Alves de; Schlickmann, Jardel; Turnes, Tiago; Caputo, Fabrizio

    2013-01-01

    O presente estudo comparou o tempo mantido acima de 90% (t90VO2max) e de 95% VO2max (t95VO2max) em três diferentes intensidades de exercício. Após a realização de um teste incremental para determinar o VO2max, oito estudantes de educação física ativos (23 ± 3 anos) executaram três sessões de exercícios intermitentes (100, 110 e 120% da velocidade do VO2max (vVO2max)) com razão esforço:recuperação de 30s:15s. O t95VO2max foi significantemente maior em 110%vVO2max (EI110%) (218,1 ± 81,6 s) quan...

  1. Speeding of pulmonary VO2 on-kinetics by light-to-moderate-intensity aerobic exercise training in chronic heart failure: clinical and pathophysiological correlates

    National Research Council Canada - National Science Library

    Mezzani, Alessandro; Grassi, Bruno; Jones, Andrew M; Giordano, Andrea; Corrà, Ugo; Porcelli, Simone; Della Bella, Silvia; Taddeo, Adriano; Giannuzzi, Pantaleo

    2013-01-01

    ...+myoglobin concentration changes (Δ[deoxy(Hb+Mb)]) in vastus lateralis muscle, ii) 8 light-to-moderate-intensity constant-work-rate exercise tests for VO2 on-kinetics phase I duration, phase II τ...

  2. Facile and Low-Temperature Fabrication of Thermochromic Cr2O3/VO2 Smart Coatings: Enhanced Solar Modulation Ability, High Luminous Transmittance and UV-Shielding Function.

    Science.gov (United States)

    Chang, Tianci; Cao, Xun; Li, Ning; Long, Shiwei; Gao, Xiang; Dedon, Liv R; Sun, Guangyao; Luo, Hongjie; Jin, Ping

    2017-08-09

    In the pursuit of energy efficient materials, vanadium dioxide (VO2) based smart coatings have gained much attention in recent years. For smart window applications, VO2 thin films should be fabricated at low temperature to reduce the cost in commercial fabrication and solve compatibility problems. Meanwhile, thermochromic performance with high luminous transmittance and solar modulation ability, as well as effective UV shielding function has become the most important developing strategy for ideal smart windows. In this work, facile Cr2O3/VO2 bilayer coatings on quartz glasses were designed and fabricated by magnetron sputtering at low temperatures ranging from 250 to 350 °C as compared with typical high growth temperatures (>450 °C). The bottom Cr2O3 layer not only provides a structural template for the growth of VO2 (R), but also serves as an antireflection layer for improving the luminous transmittance. It was found that the deposition of Cr2O3 layer resulted in a dramatic enhancement of the solar modulation ability (56.4%) and improvement of luminous transmittance (26.4%) when compared to single-layer VO2 coating. According to optical measurements, the Cr2O3/VO2 bilayer structure exhibits excellent optical performances with an enhanced solar modulation ability (ΔTsol = 12.2%) and a high luminous transmittance (Tlum,lt = 46.0%), which makes a good balance between ΔTsol and Tlum for smart windows applications. As for UV-shielding properties, more than 95.8% UV radiation (250-400 nm) can be blocked out by the Cr2O3/VO2 structure. In addition, the visualized energy-efficient effect was modeled by heating a beaker of water using infrared imaging method with/without a Cr2O3/VO2 coating glass.

  3. Oxidative stress-mediated selective antimicrobial ability of nano-VO2 against Gram-positive bacteria for environmental and biomedical applications

    Science.gov (United States)

    Li, Jinhua; Zhou, Huaijuan; Wang, Jiaxing; Wang, Donghui; Shen, Ruxiang; Zhang, Xianlong; Jin, Ping; Liu, Xuanyong

    2016-06-01

    Vanadium dioxide (VO2) is a unique thermochromic material as a result of its semiconductor-metal transition, holding great promise for energy-saving intelligent windows. Herein, pure nano-VO2 from discrete nanoparticles to continuous films were successfully deposited on quartz glass by controlling the sputtering parameters. It was demonstrated that, for Gram-positive S. aureus and S. epidermidis, the nano-VO2 could effectively disrupt bacteria morphology and membrane integrity, and eventually cause death. By contrast, the nano-VO2 did not exhibit significant toxicity towards Gram-negative E. coli and P. aeruginosa. To our knowledge, this is the first report on a selective antimicrobial effect of nano-VO2 materials on Gram-positive bacteria. Based on the experimental results, a plausible mechanism was proposed for the antimicrobial selectivity, which might originate from the different sensitivity of Gram-positive and Gram-negative bacteria to intracellular reactive oxygen species (ROS) level. Elevated intracellular ROS levels exceed the threshold that bacteria can self-regulate to maintain cellular redox homeostasis and thus cause oxidative stress, which can be alleviated by the intervention of glutathione (GSH) antioxidant. In addition, nano-VO2 did not produce significant cytotoxicity (hemolysis) against human erythrocytes within 12 h. Meanwhile, potential cytotoxicity against HIBEpiC revealed a time- and dose-dependent behavior that might be controlled and balanced by careful design. The findings in the present work may contribute to understanding the antimicrobial behavior of nano-VO2, and to expanding the new applications of VO2-based nanomaterials in environmental and biomedical fields.

  4. Blood antioxidant status in road cyclists during progressive (VO2max) and constant cyclist intensity test (MLSS).

    Science.gov (United States)

    Michalczyk, M; Poprzęcki, S; Czuba, M; Zydek, G; Jagsz, S; Sadowska-Krępa, E; Zając, A

    2015-09-01

    The aim of the study was to evaluate the effect of two different cycling intensities on the blood antioxidant status in seven road cyclists male (M) (age 25.6±4.9 years; height 1.8±0.0 m; body mass 72.4±3.4 kg, and VO2max 66.8±8.9 mL*kg-1*min-1) and six road cyclists females (F) (age 26.5±2.5 years; height 1.67 ±0.01 m; body mass 56.5±5.3 kg; and VO2max 57.2±4.1 mL*kg-1*min-1). The experiment was carried out with two tests: a progressive test (VO2max) (TP), and a 30-minute submaximal steady state test (TMLSS). The activity of superoxide dismutase, catalase (CAT), glutathione peroxidase, glutathione reductase, and creatine kinase, and the concentration of uric acid, reduced glutathione, malondialdehyde (MDA), blood lactate as well as total antioxidant potential, were assayed. Exercise significantly differentiated the activity and level of antioxidants. In both tests, after exercise a significant increase of CAT (P≤0.05) and CK (P≤0.05) activity was observed, as well as MDA (P≤0.05) level. It was demonstrated that neither the type of test (TP, TMLSS) nor the sex of the subjects exerted significant influence upon the activity of antioxidant enzymes and the level of low molecular weight antioxidants. Due to the workload in road cycling, where an average race or stage lasts a few hours, the 30-minute test was probably too weak a stimulus for the organism to disturb the pro- and antioxidative homeostasis.

  5. Effect of Sodium Phosphate Supplementation on Cycling Time Trial Performance and VO2 1 and 8 Days Post Loading

    Directory of Open Access Journals (Sweden)

    Cameron P. Brewer, Brian Dawson, Karen E. Wallman, Kym J. Guelfi

    2014-09-01

    Full Text Available This study examined the effect of 6 days of sodium phosphate (SP (50 mg·kg·FFM-1·day-1 or placebo (PL supplementation in trained cyclists on either 100 kJ (23.9 Kcal (~3-4 min or 250 kJ (59.7 Kcal (~10-12 min time trials performances both 1 and 8 days post-supplementation. Trials were performed in a counterbalanced crossover design, with a 28-day washout period between supplementation phases. No significant differences, moderate-large ES (d or likely (or greater smallest worthwhile change (SWC values were recorded for time to completion and mean power output on days 1 and 8 post-supplementation, both within and between SP and PL for either the 100 or 250 kJ (23.9 or 59.7 Kcal trials. In the 100 kJ (23.9 Kcal trial (only first minute VO2 tended to be higher in SP8 than both PL8 (d = 0.60; 88/10/2 SWC and SP1 (d = 0.47: 82/15/3 SWC, as was mean VO2 (PL8: d = 0.77; 93/6/1 SWC and SP1: d = 0.84; 90/8/3 SWC. No significant differences were found for heart rate, ratings of perceived exertion and blood lactate post-exercise within or between any trials, while serum phosphate values were not different before or after supplementation with SP or PL. In conclusion, this study showed a tendency for increased VO2 in a short duration (100 kJ/ 23.9 Kcal: ~3-4 min cycling test on day 8 after SP supplementation, but no differences in 100 or 250 kJ (23.9 or 59.7 Kcal time trials performances were observed.

  6. Hybrid Nanocomposite Films Comprising Dispersed VO2 Nanocrystals: A Scalable Aqueous-Phase Route to Thermochromic Fenestration.

    Science.gov (United States)

    Fleer, Nathan A; Pelcher, Kate E; Zou, Jian; Nieto, Kelly; Douglas, Lacey D; Sellers, Diane G; Banerjee, Sarbajit

    2017-11-08

    Buildings consume an inordinate amount of energy, accounting for 30-40% of worldwide energy consumption. A major portion of solar radiation is transmitted directly to building interiors through windows, skylights, and glazed doors where the resulting solar heat gain necessitates increased use of air conditioning. Current technologies aimed at addressing this problem suffer from major drawbacks, including a reduction in the transmission of visible light, thereby resulting in increased use of artificial lighting. Since currently used coatings are temperature-invariant in terms of their solar heat gain modulation, they are unable to offset cold-weather heating costs that would otherwise have resulted from solar heat gain. There is considerable interest in the development of plastic fenestration elements that can dynamically modulate solar heat gain based on the external climate and are retrofittable onto existing structures. The metal-insulator transition of VO2 is accompanied by a pronounced modulation of near-infrared transmittance as a function of temperature and can potentially be harnessed for this purpose. Here, we demonstrate that a nanocomposite thin film embedded with well dispersed sub-100-nm diameter VO2 nanocrystals exhibits a combination of high visible light transmittance, effective near-infrared suppression, and onset of NIR modulation at wavelengths <800 nm. In our approach, hydrothermally grown VO2 nanocrystals with <100 nm diameters are dispersed within a methacrylic acid/ethyl acrylate copolymer after either (i) grafting of silanes to constitute an amorphous SiO2 shell or (ii) surface functionalization with perfluorinated silanes and the use of a perfluorooctanesulfonate surfactant. Homogeneous and high optical quality thin films are cast from aqueous dispersions of the pH-sensitive nanocomposites onto glass. An entirely aqueous-phase process for preparation of nanocrystals and their effective dispersion within polymeric nanocomposites allows for

  7. A Device and Methodology for Measuring Repetitive Lifting VO2max (Oxygen Consumption Rate)

    Science.gov (United States)

    1987-08-01

    lifting problems. vi Introduction A task analysis of the Army’s 352 enlisted military occupational specialties revealed that more than 90% of the physically...belt. An optional leather weightlifting belt was provided, which could be worn under the cloth belt. Several subjects chose to wear the leather weight...83-0001. 5. Miller JC, Farlow DE, Seltzer ML (1977) Physiological analysis of repetitive lifting. Aviat Space Environ Med 48:984-988. 6. Mital A

  8. Strain-induced self organization of metal-insulator domains in single-crystalline VO2 nanobeams.

    Science.gov (United States)

    Wu, Junqiao; Gu, Qian; Guiton, Beth S; de Leon, Nathalie P; Ouyang, Lian; Park, Hongkun

    2006-10-01

    We investigated the effect of substrate-induced strain on the metal-insulator transition (MIT) in single-crystalline VO(2) nanobeams. A simple nanobeam-substrate adhesion leads to uniaxial strain along the nanobeam length because of the nanobeam's unique morphology. The strain changes the relative stability of the metal (M) and insulator (I) phases and leads to spontaneous formation of periodic, alternating M-I domain patterns during the MIT. The spatial periodicity of the M-I domains can be modified by changing the nanobeam thickness and the Young's modulus of the substrate.

  9. The self-paced VO2max test to assess maximal oxygen uptake in highly trained runners.

    Science.gov (United States)

    Hogg, James S; Hopker, James G; Mauger, Alexis R

    2015-03-01

    The novel self-paced maximal-oxygen-uptake (VO2max) test (SPV) may be a more suitable alternative to traditional maximal tests for elite athletes due to the ability to self-regulate pace. This study aimed to examine whether the SPV can be administered on a motorized treadmill. Fourteen highly trained male distance runners performed a standard graded exercise test (GXT), an incline-based SPV (SPVincline), and a speed-based SPV (SPVspeed). The GXT included a plateau-verification stage. Both SPV protocols included 5×2-min stages (and a plateau-verification stage) and allowed for self-pacing based on fixed increments of rating of perceived exertion: 11, 13, 15, 17, and 20. The participants varied their speed and incline on the treadmill by moving between different marked zones in which the tester would then adjust the intensity. There was no significant difference (P=.319, ES=0.21) in the VO2max achieved in the SPVspeed (67.6±3.6 mL·kg(-1)·min(-1), 95%CI=65.6-69.7 mL·kg(-1)·min(-1)) compared with that achieved in the GXT (68.6±6.0 mL·kg(-1)·min(-1), 95%CI=65.1-72.1 mL·kg(-1)·min(-1)). Participants achieved a significantly higher VO2max in the SPVincline (70.6±4.3 mL·kg(-1)·min(-1), 95%CI=68.1-73.0 mL·kg(-1)·min(-1)) than in either the GXT (P=.027, ES=0.39) or SPVspeed (P=.001, ES=0.76). The SPVspeed protocol produces VO2max values similar to those obtained in the GXT and may represent a more appropriate and athlete-friendly test that is more oriented toward the variable speed found in competitive sport.

  10. Silver Vanadium Phosphorous Oxide, Ag(2)VO(2)PO(4): Chimie Douce Preparation and Resulting Lithium Cell Electrochemistry.

    Science.gov (United States)

    Kim, Young Jin; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2011-08-15

    Recently, we have shown silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4), SVPO) to be a promising cathode material for lithium based batteries. Whereas the first reported preparation of SVPO employed an elevated pressure, hydrothermal approach, we report herein a novel ambient pressure synthesis method to prepare SVPO, where our chimie douce preparation is readily scalable and provides material with a smaller, more consistent particle size and higher surface area relative to SVPO prepared via the hydrothermal method. Lithium electrochemical cells utilizing SVPO cathodes made by our new process show improved power capability under constant current and pulse conditions over cells containing cathode from SVPO prepared via the hydrothermal method.

  11. Desenvolvimento de equações para estimativa do VO2PICO pelo teste de 9 minutos

    Directory of Open Access Journals (Sweden)

    Ana Carolina Paludo

    2014-06-01

    Full Text Available OBJETIVO: Desenvolver e validar modelos matemáticos para predição do VO2pico em crianças e adolescentes, por meio da utilização do teste de campo de corrida/caminhada de 9 minutos. MÉTODOS: Foram avaliados 211 escolares, de sete a 12 anos de idade, de ambos os sexos, regularmente matriculados em duas escolas do Município de Londrina - PR, sendo 141 escolares separados para amostra de desenvolvimento e 70 para validação das equações desenvolvidas. As medidas avaliadas foram: massa corporal, estatura, espessuras de dobras cutâneas (tricipital e subescapular, além da maturação biológica. Os testes de corrida/caminha de 9 minutos foram realizados em pista de atletismo e a análise direta do VO2pico (mL/kg/min realizada em laboratório, com analisador de gás portátil, através um teste incremental em esteira rolante. O desenvolvimento das equações foi realizado através da análise de regressão linear pelo método stepwise e a validação foi realizada pelos testes matemáticos específicos levando em consideração uma significância de 5% para todas as análises. RESULTADOS: A equação geral para a amostra total foi VO2pico= 24,506+16,672 (maturação, 0=pré e 1=púbere e pós - 0,346 (Σ DC + 5,187 (sexo, 0=F e 1=M + 0,009 (distância com um r=0,742 e EPE=9,149 mL/kg/min e sua validação apresentou r=0,570, CCI= 0,68, limites de concordância de -1,4 mL/kg/min, EPE=8,39 mL/kg/min e CV= 21,94%. CONCLUSÃO: Conclui-se que a equação generalizada desenvolvida fornece uma estimativa válida do VO2pico em crianças e adolescentes de sete a 12 anos de idade.

  12. Nonlinear interaction of infrared waves on a VO2 surface at a semiconductor-metal phase transition

    Science.gov (United States)

    Berger, N. K.; Zhukov, E. A.; Novokhatskii, V. V.

    1984-04-01

    Nonlinear interactions (including wavefront reversal) of light from CW or pulsed 10.6-micron CO2 lasers at the semiconductor-metal phase transition in a VO2 film are investigated experimentally. The results are presented in graphs and characterized in detail. The intensity reflection coefficients of the three-wave interactions are found to be 0.5 percent for a CW reference wave of intensity 900 mW/sq cm and 42 percent for a pulsed reference wave of threshold density 600-800 microjoule/sq cm.

  13. Assessment of accuracy of the Vacu-Med 17053 calibrator for ventilation, oxygen uptake (V(O(2))), and carbon dioxide production (V(CO(2))).

    Science.gov (United States)

    Bunn, Jennifer A; Pittsley, Jesse L; Baker, Scott V; Yates, Jw

    2011-04-01

    Few have examined the accuracy of mechanical calibrators used to calibrate metabolic monitors. To evaluate the Vacu-Med 17053 motorized syringe calibrator for accuracy against the accepted standard method: the Douglas bag. We tested oxygen consumption values (V(O(2))) of 522-3,210 mL/min. We mixed room air and calibration gases in the pumping syringes of the Vacu-Med 17053 and evacuated those gases into a Douglas bag, measured the Douglas bag volumes and concentrations, and converted to pulmonary ventilation, V(O(2)), and carbon dioxide production (V(CO(2))). The Vacu-Med 17053 calibrator overestimated V(O(2)) by a mean 28.6 mL/min (1.3% error), underestimated V(CO(2)) by 6.9 mL/min (-1.7% error), and underestimated pulmonary ventilation by 0.98 L/min (-1.4% error). The V(O(2)) and V(CO(2)) differences between the calibrator and the Douglas bag were larger at higher V(O(2)) levels. The V(O(2)) and V(CO(2)) differences might be attributable to fluctuations of the calibrator settings. The Vacu-Med 17053 calibrator was accurate with the application of a mathematical correction.

  14. Association of lower urinary tract symptoms and maximal oxygen uptake (VO2max) in men aged 50 to 59 years: a case-control study.

    Science.gov (United States)

    Brum, Christiano Silva; Rezende, Edson Campana; de Lima, Jorge Roberto Perrout; Santos, Isaias Chaves; Netto, Jose Murilo Bastos; Figueiredo, André Avarese

    2013-10-01

    To determine the association of lower urinary tract symptoms (LUTS) with maximal oxygen uptake (VO2max), flexibility, physical activity level, and anthropometric variables. A case-control study has been conducted in which LUTS was the outcome and VO2max, flexibility, physical activity level, and anthropometric variables the exposure variables. We evaluated 100 men aged between 50 and 59 years, assigning 49 to the case group and 51 to the control group. The patients underwent the following: physical activity level assessment using the International Physical Activity Questionnaire; LUTS assessment using the International Prostate Symptom Score Questionnaire; anthropometric assessment measuring body mass index, waist-to-hip ratio, and waist circumference; VO2max assessment through the Polar Fitness Test; and flexibility assessment using the Sit and Reach test. Multivariable analysis using a logistic regression model was performed for the assessment of odds ratio (OR) and 95% confidence interval (95% CI). In bivariable analysis, a statistically significant association was identified for LUTS with physical activity level (OR = 0.375, 95% CI = 0.167-0.841, P = .02); with VO2max (OR = 0.206, 95% CI = 0.086-0.495, P VO2max was the only statistically significant variable associated with LUTS (OR = 0.303, 95% CI = 0.105-0.875, P = .027). In men aged between 50 and 59 years, an association between inadequate VO2max with LUTS was found. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Thermochromic properties of W-doped VO2 thin films deposited by aqueous sol-gel method for adaptive infrared stealth application

    Science.gov (United States)

    Liu, Dongqing; Cheng, Haifeng; Xing, Xin; Zhang, Chaoyang; Zheng, Wenwei

    2016-07-01

    The W doped VO2 thin films with various W contents were successfully deposited by aqueous sol-gel method followed by a post annealing process. The derived thin films were characterized by X-ray diffraction, Raman spectra, scanning electron microscopy and atomic force microscopy. Besides, the resistance-temperature relationship and infrared emissivity in the waveband 7.5-14 μm were analyzed, and the effects of W doping on the thermochromic properties of VO2 thin films were studied. The results show that W atoms enter the crystal lattice of VO2 and the transition temperature decreases gradually with increasing doping amount of W. The emissivity of VO2-W-4% thin films has dropped to 0.4 when its real temperature is above 30 °C. The thermal infrared images were also examined under different temperature by thermal imager. The results indicate that the temperature under which W doped VO2 thin films begin to have lower emissivity decreases gradually with increasing doping amount of W. W doped VO2 thin films can control its infrared radiation intensity actively at a lower temperature level of 30 °C, which has great application prospects in the adaptive infrared stealth technology.

  16. A acurácia da determinação do VO2max e do limiar anaeróbio La exactitud en la determinacion del VO2máx y del umbral anaerobico Accuracy of VO2max and anaerobic threshold determination

    Directory of Open Access Journals (Sweden)

    Paulo Cesar N Granja Filho

    2005-06-01

    Full Text Available São raros estudos que tratam da acurácia de parâmetros de trocas gasosas durante o esforço, com a população brasileira. OBJETIVO: Determinar a confiabilidade do consumo máximo de oxigênio (VO2max e do limiar anaeróbio (LAn, assim como, a objetividade do segundo (LAn em adultos jovens saudáveis. MÉTODOS: Foram aplicados dois testes de esforço máximo, a partir dos quais dois observadores independentes determinaram o LAn através do método de inspeção visual. Os dados foram tratados por meio da análise de regressão, coeficiente de correlação intraclasse (CCI, ANOVA com dois fatores com teste post hoc de Tukey e teste t pareado para alfa Son raros los estudios que tratan de la exactitud de los parámetros de cambios gaseosos durante el esfuerzo con la población brasileña. OBJETIVO: Determinar la confiabilidad del consumo máximo de oxigeno (VO2max y del umbral anaeróbico (LAn, así como la objetividad del segundo, (LAn en adultos jovenes saludables. MÉTODOS: Fueron aplicados dos tests de esfuerzo máximo, a partir de los cuales dos observadores independientes determinaron el LAn a través del método de inspección visual. Los datos fueron tratados por medio del análisis de regresión, coeficiente de relación intraclase (CCI, ANOVA com dos factores con test post hoc de Tukey y el test t apareado para alfa Studies on the accuracy of the gas exchange and ventilation parameters during exertion involving the Brazilian population are scarce in literature. OBEJCTIVE: To determine the reliability of the maximal oxygen intake (VO2max and anaerobic threshold (AnT, as well as the objectivity of the AnT determination in Brazilian healthy youth adults. METHODS: Two tests of maximal exertion were applied. Two independent observers applied the visual inspection method for the AnT determination. The data were compared by means of the regression analysis, intraclass correlation coefficient (ICC, two-way ANOVA and the paired t-test for an

  17. The impact of decreasing cutoff values for maximal oxygen consumption (VO2max) in the decision-making process for candidates to lung cancer surgery

    Science.gov (United States)

    Gatani, Tindaro; Di Maio, Massimo; Meoli, Ilernando; La Rocca, Antonello; Martucci, Nicola; La Manna, Carmine; Stefanelli, Francesco

    2013-01-01

    Background Maximal oxygen consumption (VO2max) is considered a decisive test for risk prediction in patients with borderline cardiopulmonary reserve. Guidelines have adopted decreasing VO2max cut-off values to define operability within acceptable mortality and morbidity limits. We wanted to investigate how the adoption of decreasing VO2max cut-off-values assessment contributed to better select lung surgery candidates. Methods One hundred and nineteen consecutive surgical candidates have been prospectively analyzed as a sample population. Preoperative work-up included spirometry and transfer factor (DLco); irrespective of the spirometric values, these patients were subjected to VO2max assessment. Surgical eligibility was decided by the same surgeon throughout the series. In the postoperative period, overall mortality and the occurrence of any, major or minor complications was recorded and graded according to the Common Terminology Criteria for Adverse Events v.4.3. Results Three arbitrary cut-offs were introduced at 15, 14 and 12 mL.kg-1.min-1. Notably, 15 and 12 mL.kg-1.min-1 correlated with percentage VO2max values of 50% and 35% of predicted (PVO2max less than 35% (P=0.0017) and CTCAE >2 (P=0.0457) emerged as significant predictors of survival after surgery. Conversely on logistic regression analysis, age over 70 years (P=0.03) and pneumonectomy (P=0.001), but not VO2max cut-off values, were significant predictors of major (CTCAE >2) morbidity. Conclusions Since VO2max is increasingly used to contribute to risk prediction for the individual patient, surgeons need to be advised that the concept of a definitive, generalized cut-off value for VO2max is probably a contradiction in terms. Patient-specific VO2max values are more likely to contribute to risk assessment since they may reflect the primarily affected component among the determinants of maximal oxygen consumption. Whether patient-specific VO2max should be routinely used by surgeons to define operability for

  18. Resistance noise spectroscopy across the thermally and electrically driven metal-insulator transitions in VO2 nanobeams

    Science.gov (United States)

    Alsaqqa, Ali; Kilcoyne, Colin; Singh, Sujay; Horrocks, Gregory; Marley, Peter; Banerjee, Sarbajit; Sambandamurthy, G.

    Vanadium dioxide (VO2) is a strongly correlated material that exhibits a sharp thermally driven metal-insulator transition at Tc ~ 340 K. The transition can also be triggered by a DC voltage in the insulating phase with a threshold (Vth) behavior. The mechanisms behind these transitions are hotly discussed and resistance noise spectroscopy is a suitable tool to delineate different transport mechanisms in correlated systems. We present results from a systematic study of the low frequency (1 mHz noise behavior in VO2 nanobeams across the thermally and electrically driven transitions. In the thermal transition, the power spectral density (PSD) of the resistance noise is unchanged as we approach Tc from 300 K and an abrupt drop in the magnitude is seen above Tc and it remains unchanged till 400 K. However, the noise behavior in the electrically driven case is distinctly different: as the voltage is ramped from zero, the PSD gradually increases by an order of magnitude before reaching Vth and an abrupt increase is seen at Vth. The noise magnitude decreases above Vth, approaching the V = 0 value. The individual roles of percolation, Joule heating and signatures of correlated behavior will be discussed. This work is supported by NSF DMR 0847324.

  19. Low-temperature CVD synthesis of patterned core-shell VO2@ZnO nanotetrapods and enhanced temperature-dependent field-emission properties

    Science.gov (United States)

    Yin, Haihong; Yu, Ke; Song, Changqing; Wang, Zhiliang; Zhu, Ziqiang

    2014-09-01

    VO2 nanostructures are attractive materials because of their reversible metal-insulator transition (MIT) and wide applications in devices. When they are used as field emitters, a new type of temperature-controlled field emission device can be fabricated. Vapor transport methods used to synthesize traditional VO2 nanostructures are energy-intensive, low yield, and produce simple morphology (quasi-1D) that exhibits substrate clamping; thus they are not suitable for field emission applications. To overcome these limitations, ZnO nanotetrapods were used as templates, and patterned core-shell VO2@ZnO nanotetrapods were successfully grown on an ITO/glass substrate via a low-temperature CVD synthesis. SEM, TEM, EDX, XPS analyses and X-ray diffraction revealed that the cores and shells of these nanotetrapods were single crystal wurtzite-type ZnO and polycrystalline VO2, respectively. The VO2@ZnO nanotetrapods show strongly MIT-related FE properties, the emission current density at low temperature is significantly enhanced in comparison with pure VO2 nanostructures, and the emission current density increased by about 20 times as the ambient temperature increased from 25 to 105 °C at a fixed field of 5 V μm-1. Although the VO2@ZnO nanotetrapods show a worse FE performance at low temperatures compared with pure ZnO nanotetrapods, the FE performance was substantially improved at high temperatures, which was attributed to the MIT-related band bending near the interface and the abrupt resistance change across the MIT.

  20. The Effect of Training Intensity on VO2max in Young Healthy Adults: A Meta-Regression and Meta-Analysis.

    Science.gov (United States)

    Scribbans, Trisha D; Vecsey, Stephan; Hankinson, Paul B; Foster, William S; Gurd, Brendon J

    Exercise training at a variety of intensities increases maximal oxygen uptake (VO2max), the strongest predictor of cardiovascular and all-cause mortality. The purpose of the present study was to perform a systematic review, meta-regression and meta-analysis of available literature to determine if a dose-response relationship exists between exercise intensity and training-induced increases in VO2max in young healthy adults. Twenty-eight studies involving human participants (Mean age: 23±1 yr; Mean VO2max: 3.4±0.8 l·min-1) were included in the meta-regression with exercise training intensity, session dose, baseline VO2max, and total training volume used as covariates. These studies were also divided into 3 tertiles based on intensity (tertile 1: ~60-70%; 2: ~80-92.5%; 3: ~100-250%VO2max), for comparison using separate meta-analyses. The fixed and random effects meta-regression models examining training intensity, session dose, baseline VO2max and total training volume was non-significant (Q4=1.36; p=0.85; R2=0.05). There was no significant difference between tertiles in mean change in VO2max (tertile 1:+0.29±0.15 l/min, ES (effect size) =0.77; 2:+0.26±0.10 l/min, ES=0.68; 3:+0.35±0.17 l/min, ES=0.80), despite significant (ptraining volume as training intensity increased. These data suggest that exercise training intensity has no effect on the magnitude of training-induced increases in maximal oxygen uptake in young healthy human participants, but similar adaptations can be achieved in low training doses at higher exercise intensities than higher training doses of lower intensity (endurance training).

  1. Influência do estado nutricional e do VO2max nos níveis de adiponectina em homens acima de 35 anos Influencia del Estado Nutricional y del VO2max en los Niveles de Adiponectina en Hombres que superan los 35 Años Influence of nutritional status and VO2max on adiponectin levels in men older than 35 years

    Directory of Open Access Journals (Sweden)

    Eduardo Camillo Martinez

    2011-06-01

    Full Text Available FUNDAMENTO: A adiponectina é considerada importante fator na patogênese das doenças cardiovasculares e metabólicas, por suas propriedades antiaterogênicas e antiinflamatórias. Poucos estudos, entretanto, sugerem a existência de relação direta entre os níveis de adiponectina e os níveis de condicionamento cardiorrespiratório e atividade física. OBJETIVO: Verificar a influência do estado nutricional e do condicionamento cardiorrespiratório nos níveis plasmáticos de adiponectina em homens adultos. MÉTODOS: Foram avaliados 250 sujeitos, homens, todos militares da ativa do Exército Brasileiro (42,6 ± 4,8 anos. Foram mensurados os níveis plasmáticos de adiponectina, massa corporal, estatura, circunferência da cintura (CC, percentual de gordura por pesagem hidrostática e VO2max por ergoespirometria. Um questionário foi utilizado para obter as características do treinamento físico realizado pelos sujeitos. RESULTADOS: Na amostra, 121 (48% sujeitos apresentaram sobrepeso e 36 (14% eram obesos. Ainda, 66 sujeitos (27% apresentaram percentual de gordura maior que 25% e 26.7% apresentaram CC > 94 cm. Sujeitos com sobrepeso e obesidade apresentaram valores significativamente menores de adiponectina em relação aqueles com estado nutricional normal. Sujeitos no mais alto tercil de VO2max apresentaram níveis de adiponectina mais altos que os demais. Os níveis de adiponectina estiveram positivamente correlacionados com o tempo total de treinamento físico semanal e com o VO2max e inversamente correlacionados com os valores de massa corporal, IMC e CC. A correlação dos níveis de adiponectina e do VO2max não permaneceu significante após controlada pelo IMC e CC. CONCLUSÃO: Sujeitos com melhor condicionamento cardiorrespiratório e com estado nutricional normal parecem apresentar níveis mais saudáveis de adiponectina.FUNDAMENTO: La adiponectina es considerada un importante factor en la patogénesis de las enfermedades

  2. Efeitos do estado e especificidade do treinamento aeróbio na relação %VO2max versus %FCmax durante o ciclismo Effects of the state and specificity of aerobic training on the %VO2max versus %HRmax ratio during cycling

    Directory of Open Access Journals (Sweden)

    Fabrizio Caputo

    2005-01-01

    Full Text Available OBJETIVO: Determinar os efeitos do estado e especificidade de treinamento aeróbio na relação entre o percentual do consumo máximo de oxigênio (%VO2max e o percentual da frequência cardíaca máxima (%FCmax durante o exercício incremental realizado no cicloergômetro. MÉTODOS: Sete corredores, 9 ciclistas, 11 triatletas e 12 sedentários, todos do sexo masculino e aparentemente saudáveis, foram submetidos a um teste incremental até a exaustão no cicloergômetro. Regressões lineares entre %VO2max e %FCmax foram determinadas para cada indivíduo. Com base nessas regressões, foram calculados %FCmax correspondentes a determinados %VO2max (50, 60, 70, 80 e 90% de cada participante. RESULTADOS: Não foram encontradas diferenças significantes entre todos os grupos nos %FCmax para cada um dos %VO2max avaliados. Analisando-se os voluntários como um único grupo, as médias dos %FCmax correspondentes a 50, 60, 70, 80 e 90% %VO2max foram 67, 73, 80, 87, e 93%, respectivamente. CONCLUSÃO: Nos grupos analisados, a relação entre o %VO2max e %FCmax durante o exercício incremental no ciclismo não é dependente do estado e especificidade do treinamento aeróbio.OBJECTIVE: To determine the effects of the status and specificity of exercise training in the ratio between maximum oxygen consumption (%VO2max and the percentage of maximal heart rate (%HRmax during incremental exercise on a cycle ergometer. METHODS: Seven runners, 9 cyclists, 11 triathletes, and 12 sedentary individuals, all male and apparently healthy, underwent exhaustive incremental exercise on cycle ergometers. Linear regressions between %VO2max x %HRmax were determined for each individual. Based on these regressions, %HRmax was assessed corresponding to a determined %VO2max (50, 60, 70, 80, and 90% from each participant. RESULTS: Significant differences were not found between the groups in %HRmax for each of the %VO2max assessed. Analyzing the volunteers as a single group, the

  3. PELATIHAN LARI SIRKUIT 2 X 10 MENIT DAN PELATIHAN LARI KONTINYU 2 X 10 MENIT DAPAT MENINGKATKAN VO2 MAX TAEKWONDOIN PUTRA KABUPATEN MANGGARAI - NTT

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    Regina Sesilia Noy

    2014-08-01

    Full Text Available VO2 max is very important in everyday life, so as to facilitate any physicalactivity, specially for athletes in order to achieve maximum performance. In aneffort to increase VO2 max training should be carried out regularly, measured andplanned. This study aims to determine the increase in VO2 max through circuittraining run and run continuously. The sample is taekwondoin son Manggarai-NTTwith an average age of 15 years. This study is an experimental study with the studydesign used was Randomized Pre and Post Test Group desigen. With a totalsample of 7 people in each group. Samples were randomly selected. Treatmentgroup 1 (KP1 given training run circuit 2 x 10 minute and Treatment Group 2(KP2 are given continuous training run 2 x 10 minute. Training carried out for 6weeks with a frequency of four times a week starting at 17:00 to 18:00 pm locatedat Frans Sales Lega Airport Manggarai-NTT. The analysis showed an increase inVO2 max was significantly (p <0.05 against both groups fled. In both groups thecircuit run by Pulse Oxymeter and Norma Cooper an increase in VO2 max with p<0.05, as well as a continuous run either by Pulse Oxymeter and Norma Cooperwith an increase in VO2 max value of p <0.05. The results of this analysis meansthat either the training or circuit training run run continuously to improve VO2max. Based on a comparison of test data by an independent test after training inboth groups either by Pulse Oxymeter and Norma Cooper in get p values > 0.05, orthere is no significant difference. Based on these results it can be concluded thatthe run circuit training and continuous training run together can increase VO2 maxand there was no significant difference. The results of this study are expected toincrease the knowledge of coaches, teachers and taekwondoin to perform trainingon a regular basis and are also expected to do similar research that examines VO2max with different training.

  4. Validity of treadmill- and track-based individual calibration methods for estimating free-living walking speed and VO2 using the Actigraph accelerometer.

    Science.gov (United States)

    Barnett, Anthony; Cerin, Ester; Vandelanotte, Corneel; Matsumoto, Aya; Jenkins, David

    2015-01-01

    For many patients clinical prescription of walking will be beneficial to health and accelerometers can be used to monitor their walking intensity, frequency and duration over many days. Walking intensity should include establishment of individual specific accelerometer count, walking speed and energy expenditure (VO2) relationships and this can be achieved using a walking protocol on a treadmill or overground. However, differences in gait mechanics during treadmill compared to overground walking may result in inaccurate estimations of free-living walking speed and VO2. The aims of this study were to compare the validity of track- and treadmill-based calibration methods for estimating free-living level walking speed and VO2 and to explain between-method differences in accuracy of estimation. Fifty healthy adults [32 women and 18 men; mean (SD): 40 (13) years] walked at four pre-determined speeds on an outdoor track and a treadmill, and completed three 1-km self-paced level walks while wearing an Actigraph monitor and a mobile oxygen analyser. Speed- and VO2-to-Actigraph count individual calibration equations were computed for each calibration method. Between-method differences in calibration equation parameters, prediction errors, and relationships of walking speed with VO2 and Actigraph counts were assessed. The treadmill-calibration equation overestimated free-living walking speed (on average, by 0.7 km · h(-1)) and VO2 (by 4.99 ml · kg(-1) · min(-1)), while the track-calibration equation did not. This was because treadmill walking, from which the calibration equation was derived, produced lower Actigraph counts and higher VO2 for a given walking speed compared to walking on a track. The prediction error associated with the use of the treadmill-calibration method increased with free-living walking speed. This issue was not observed when using the track-calibration method. The proposed track-based individual accelerometer calibration method can

  5. Strain Effects in Epitaxial VO2 Thin Films on Columnar Buffer-Layer TiO2/Al2O3 Virtual Substrates.

    Science.gov (United States)

    Breckenfeld, Eric; Kim, Heungsoo; Burgess, Katherine; Charipar, Nicholas; Cheng, Shu-Fan; Stroud, Rhonda; Piqué, Alberto

    2017-01-18

    Epitaxial VO2/TiO2 thin film heterostructures were grown on (100) (m-cut) Al2O3 substrates via pulsed laser deposition. We have demonstrated the ability to reduce the semiconductor-metal transition (SMT) temperature of VO2 to ∼44 °C while retaining a 4 order of magnitude SMT using the TiO2 buffer layer. A combination of electrical transport and X-ray diffraction reciprocal space mapping studies help examine the specific strain states of VO2/TiO2/Al2O3 heterostructures as a function of TiO2 film growth temperatures. Atomic force microscopy and transmission electron microscopy analyses show that the columnar microstructure present in TiO2 buffer films is responsible for the partially strained VO2 film behavior and subsequently favorable transport characteristics with a lower SMT temperature. Such findings are of crucial importance for both the technological implementation of the VO2 system, where reduction of its SMT temperature is widely sought, as well as the broader complex oxide community, where greater understanding of the evolution of microstructure, strain, and functional properties is a high priority.

  6. Joule-heat-driven high-efficiency electronic-phase switching in freestanding VO2/TiO2 nanowires

    Science.gov (United States)

    Higuchi, Yoshiyuki; Kanki, Teruo; Tanaka, Hidekazu

    2017-03-01

    In this study, we demonstrated that an insulator-to-metal transition is driven by a low electric power using freestanding structures with two different sizes. The critical power (P C) required to induce the insulator-to-metal transition was measured with clamped and freestanding nanowires. The required P C for 400-nm-wide freestanding nanowires was 483 nW at a temperature 2 K lower than the temperature of the insulator-to-metal transition. This P C value is approximately 1 order of magnitude smaller than that for freestanding microwires with a width of 1 µm. The thermal dissipation model explains the changes in P C. These results provide guidelines for achieving significant reductions in P C in two-terminal VO2 phase-switching devices.

  7. In situ atom scale visualization of domain wall dynamics in VO2 insulator-metal phase transition.

    Science.gov (United States)

    He, Xinfeng; Xu, Tao; Xu, Xiaofeng; Zeng, Yijie; Xu, Jing; Sun, Litao; Wang, Chunrui; Xing, Huaizhong; Wu, Binhe; Lu, Aijiang; Liu, Dingquan; Chen, Xiaoshuang; Chu, Junhao

    2014-10-08

    A domain wall, as a device, can bring about a revolution in developing manipulation of semiconductor heterostructures devices at the atom scale. However, it is a challenge for these new devices to control domain wall motion through insulator-metal transition of correlated-electron materials. To fully understand and harness this motion, it requires visualization of domain wall dynamics in real space. Here, domain wall dynamics in VO2 insulator-metal phase transition was observed directly by in situ TEM at atom scale. Experimental results depict atom scale evolution of domain morphologies and domain wall exact positions in (202) and (040) planes referring to rutile structure at 50°C. In addition, microscopic mechanism of domain wall dynamics and accurate lattice basis vector relationship of two domains were investigated with the assistance of X-ray diffraction, ab initio calculations and image simulations. This work offers a route to atom scale tunable heterostructure device application.

  8. Room Temperature Optical Constants and Band Gap Evolution of Phase Pure M1-VO2 Thin Films Deposited at Different Oxygen Partial Pressures by Reactive Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Meng Jiang

    2014-01-01

    Full Text Available Spectroscopic ellipsometry study was employed for phase pure VO2(M1 thin films grown at different oxygen partial pressures by reactive magnetron sputtering. The optical constants of the VO2(M1 thin films have been determined in a photon energy range between 0.73 and 5.05 eV. The near-infrared extinction coefficient and optical conductivity of VO2(M1 thin films rapidly increase with decreasing O2-Ar ratios. Moreover, two electronic transitions can be uniquely assigned. The energy gaps correlated with absorption edge (E1 at varied O2-Ar ratios are almost the same (~2.0 eV; consequently, the absorption edge is not significantly changed. However, the optical band gap corresponding to semiconductor-to-metal phase transition (E2 decreases from 0.53 to 0.18 eV with decreasing O2-Ar ratios.

  9. The role of haemoglobin mass on VO(2)max following normobaric 'live high-train low' in endurance-trained athletes

    DEFF Research Database (Denmark)

    Robach, Paul; Siebenmann, Christoph; Jacobs, Robert A

    2012-01-01

    It remains unclear by which mechanism 'live high-train low' (LHTL) altitude training increases exercise performance. Haematological and skeletal muscle adaptations have both been proposed. To test the hypotheses that (i) LHTL improves maximal oxygen uptake (VO(2)max) and (ii) this improvement...... abolished by isovolumic haemodilution. We obtained skeletal muscle biopsies to quantify mitochondrial oxidative capacity and efficiency. Sixteen endurance-trained athletes were assigned (double-blinded, placebo controlled) to =16 h/day over 4 weeks to normoxia (placebo, n=6) or normobaric hypoxia equivalent...... to 3000 m altitude (LHTL, n=10). Four-week LHTL did not increase VO(2)max, irrespective of treatment (LHTL: 1.5%; placebo: 2.0%). Hb(mass) was slightly increased (4.6%) in 5 (of 10) LHTL subjects but this was not accompanied by a concurrent increase in VO(2)max. In the subjects demonstrating an increase...

  10. Large modification in insulator-metal transition of VO2 films grown on Al2O3 (001) by high energy ion irradiation in biased reactive sputtering

    Science.gov (United States)

    Azhan, Nurul Hanis; Okimura, Kunio; Ohtsubo, Yoshiyuki; Kimura, Shin-ichi; Zaghrioui, Mustapha; Sakai, Joe

    2016-02-01

    High energy ion irradiation in biased reactive sputtering enabled significant modification of insulator-metal transition (IMT) properties of VO2 films grown on Al2O3 (001). Even at a high biasing voltage with mean ion energy of around 325 eV induced by the rf substrate biasing power of 40 W, VO2 film revealed low IMT temperature (TIMT) at 309 K (36 °C) together with nearly two orders magnitude of resistance change. Raman measurements from -193 °C evidenced that the monoclinic VO2 lattice begins to transform to rutile-tetragonal lattice near room temperature. Raman spectra showed the in-plane compressive stress in biased VO2 films, which results in shortening of V-V distance along a-axis of monoclinic structure, aM-axis (cR-axis) and thus lowering the TIMT. In respect to that matter, significant effects in shortening the in-plane axis were observed through transmission electron microscopy observations. V2p3/2 spectra from XPS measurements suggested that high energy ion irradiation also induced oxygen vacancies and resulted for an early transition onset and rather broader transition properties. Earlier band gap closing against the temperature in VO2 film with higher biasing power was also probed by ultraviolet photoelectron spectroscopy. Present results with significant modification of IMT behavior of films deposited at high-energy ion irradiation with TIMT near the room temperature could be a newly and effective approach to both exploring mechanisms of IMT and further applications of this material, due to the fixed deposition conditions and rather thicker VO2 films.

  11. Estimated VO2max and its corresponding velocity predict performance of amateur runners. DOI:10.5007/1980-0037.2012v14n2p192

    Directory of Open Access Journals (Sweden)

    Tony Meireles Santos

    2012-02-01

    Full Text Available In recent years, there has been a substantial increase in the number of runners, with a proportional increase in their involvement in amateur street competition. Identification of the determinants of performance in this population appears necessary for optimization of time devoted to training. The objective of this study was to ascertain the association between estimated maximal oxygen uptake (VO2max, critical velocity (CV and VO2max velocity (VVO2max and athletic performance in the 3.6 km (uphill and 10 and 21.1 km (flatland events. Twelve amateur runners (nine male, mean age 36 ± 5 years underwent five tests: 1 and 5 km race on level ground, 3.6 km race with slope (≈8%, and indirect VO2max measurement. CV was determined from the linear relationship between distance and run time on the first two tests. The subjects then took part in two official 10 km and 21.1 km (half marathon races. VVO2max was calculated from the VO2max through a metabolic equation. VO2max showed the best association with running performance in the 10 and 21.1 km events. For the uphill race, VVO2max showed a better association. Overall, the variable with the highest average association was VO2max (0.91±0.07, followed by VVO2max (0.90±0.04 and VC (0.87±0.06. This study showed strong associations between physiological variables established by low-cost, user-friendly indirect methods and running performance in the 10 and 21.1 km (flatland and 3.6 km (uphill running events.

  12. New intelligent multifunctional SiO2/VO2 composite films with enhanced infrared light regulation performance, solar modulation capability, and superhydrophobicity.

    Science.gov (United States)

    Wang, Chao; Zhao, Li; Liang, Zihui; Dong, Binghai; Wan, Li; Wang, Shimin

    2017-01-01

    Highly transparent, energy-saving, and superhydrophobic nanostructured SiO2/VO2 composite films have been fabricated using a sol-gel method. These composite films are composed of an underlying infrared (IR)-regulating VO2 layer and a top protective layer that consists of SiO2 nanoparticles. Experimental results showed that the composite structure could enhance the IR light regulation performance, solar modulation capability, and hydrophobicity of the pristine VO2 layer. The transmittance of the composite films in visible region (Tlum) was higher than 60%, which was sufficient to meet the requirements of glass lighting. Compared with pristine VO2 films and tungsten-doped VO2 film, the near IR control capability of the composite films was enhanced by 13.9% and 22.1%, respectively, whereas their solar modulation capability was enhanced by 10.9% and 22.9%, respectively. The water contact angles of the SiO2/VO2 composite films were over 150°, indicating superhydrophobicity. The transparent superhydrophobic surface exhibited a high stability toward illumination as all the films retained their initial superhydrophobicity even after exposure to 365 nm light with an intensity of 160 mW . cm-2 for 10 h. In addition, the films possessed anti-oxidation and anti-acid properties. These characteristics are highly advantageous for intelligent windows or solar cell applications, given that they can provide surfaces with anti-fogging, rainproofing, and self-cleaning effects. Our technique offers a simple and low-cost solution to the development of stable and visible light transparent superhydrophobic surfaces for industrial applications.

  13. Evaluation of Maximal Oxygen Uptake (V02max) and Submaximal Estimates of VO2max Before, During and After Long Duration ISS Missions

    Science.gov (United States)

    Moore, Alan; Evetts, Simon; Feiveson, Alan; Lee, Stuart; McCleary, Frank; Platts, Steven

    2009-01-01

    NASA's Human Research Program Integrated Research Plan (HRP-47065) serves as a road-map identifying critically needed information for future space flight operations (Lunar, Martian). VO2max (often termed aerobic capacity) reflects the maximum rate at which oxygen can be taken up and utilized by the body during exercise. Lack of in-flight and immediate postflight VO2max measurements was one area identified as a concern. The risk associated with not knowing this information is: Unnecessary Operational Limitations due to Inaccurate Assessment of Cardiovascular Performance (HRP-47065).

  14. La importancia del VO2max para realizar esfuerzos intermitentes de alta intensidad en el fútbol femenino de élite

    OpenAIRE

    Arecheta Pérez, Carlos; Gómez López, María Teresa; Lucía Mulas, Alejandro

    2006-01-01

    Objetivo: Determinar la importancia del VO2max en un equipo de fútbol femenino español, analizando si existe alguna relación entre esta variable y la capacidad para efectuar repetidos esfuerzos intermitentes de alta intensidad. Métodos: Participaron 10 jugadoras de fútbol pertenecientes al equipo profesional Rayo Vallecano, (20,3 ± 2,8 años) quienes realizaron: 1) un test en tapiz rodante para determinar el VO2max y 2) el test de Bangsbo que consta de siete sprints con una recuperación act...

  15. Estimativa das contribuições dos sistemas anaeróbio lático e alático durante exercícios de cargas constantes em intensidades abaixo do VO2max Estimation of contributions of the anaerobic lactic and alactic systems during constant-load exercises at intensities below the VO2max

    Directory of Open Access Journals (Sweden)

    Marcos David Silva-Cavalcante

    2013-01-01

    Full Text Available O objetivo do estudo foi estimar as contribuições do metabolismo anaeróbio lático (MAL e alático (MAA em intensidades abaixo do consumo máximo de oxigênio (VO2max. Dez homens (23 ± 4 anos, 176,4 ± 6,8 cm, 72,4 ± 8,2 kg, 12,0 ± 4,5 % de gordura corporal realizaram um teste progressivo até a exaustão voluntária para identificação do VO2max, da potência correspondente ao VO2max (WVO2max e do segundo limiar ventilatório (LV2. Na segunda e na terceira visita foram realizados seis testes de cargas constantes (três testes por sessão com intensidades abaixo do VO2max. Houve uma predominância do MAL sobre o MAA durante os exercícios submáximos a partir da intensidade correspondente ao LV2, sendo significativamente maior em 90% VO2max (p The purpose this study was that estimated contributions of the anaerobic lactic (MAL and alactic (MAA metabolism during constant load exercises at intensities below the maximal oxygen capacity uptake (VO2max. Ten males (23 ± 4 years, 176.4 ± 6.8 cm, 72.4 ± 8.2 kg, 12.0 ± 4.5 % of fat body performed in the first visit a progressive test until exhaustion to identification of VO2max, power output corresponding to the VO2max (WVO2max and second ventilatory threshold (LV2. On the second and third visit, the participants performed six constant workload tests (3 per session with intensities below VO2max. There was a predominance of MAL about MAA during the exercises sub-maximal from intensity corresponding to the LV2, being significantly higher at 90% VO2max (p < 0.05. Thus, these results may help coaches to implement training loads appropriate to their athletes, according to the metabolic demand of the competition.

  16. Body composition, VO2máx. and the lifestyle of young students of the higher education

    Directory of Open Access Journals (Sweden)

    R.M. Antúnez

    2008-01-01

    Full Text Available OBJECTIVE: The purpose of this study was to characterize the subjects of the sample in what concerns their corporal composition, through the index of corporal mass and of the percentage of fat mass, their cardiorespiratory capacity, their eating and smoking habits, and indexes of practice of physical activity. It also aimed to verify if there were statistically relevant relationships between these variables. METHODS: The study was carried out in 2006 and 2007, in Beja, a city in the South of Portugal. The sample comprised 183 students attending the first year of all the courses of a higher education institution in the school year of 2006/07, with ages ranging from 18 to 40 years old. Through a questionnaire, the Astrand Test, and the technique of electric bioimpedance, we obtained the results that allowed us to reach the intended objectives. We used the program Bodygram to obtain the data related to the index of corporal mass and the percentage of fat mass, and the program SPSS, version 14.0, to accomplish the descriptive analysis of the data, a variance analysis and also a correlational analysis. RESULTS: We found evidence that 62.8% of the subjects of the sample presented values of percentage of fat mass above the recommended limits and that 55.7% obtained very low values of VO2max. We also found that 61.7% didn't consider themselves active subjects in what concerns the regular practice of physical activity, and that this variable was correlated with VO2máx. (p=0.01 CONCLUSIONS: We could conclude that most of the subjects of our sample presented low indexes of physical activity, deficient cardiorespiratory capacity and high values in what concerns the percentage of fat mass. The practice of physical activity showed to be positively correlated with the cardiorespiratory capacity. It is necessary to implement more effective campaigns to combat obesity and to sensitize for the regular practice of physical activity and for good eating habits.

  17. Comparison of VO2 Max Prediction Value, Physiological Response, and Borg Scale between 12-Minute and 3200-Meter Run Fitness Tests among Indonesian Army Soldiers

    Directory of Open Access Journals (Sweden)

    Maulidi Abdillah

    2016-09-01

    Full Text Available Objective: To compare the VO2 max and physiological responses between 12-minute and 3200-meter run fitness tests. Methods: The subjects were 40 soldiers aged 18–21 years old of the Infantry Battalion 303/SSM of Cikajang, Garut, West Java, Indonesia. The 12-minute and 3200-meter run fitness tests were conducted with one week resting period. The measurement of the VO2 max prediction was based on each of the formulations and the measurement of physiological response included blood pressure, heart rate, respiratory rate, Borg scale and oxygen saturation before and after the tests. This study used a cross-sectional method while the data were analyzed statistically using t-test (p=0.05. Results: The results showed that the VO2 max prediction in 12-minute run fitness test was 52.046±2.980 mL/KgBB/min and the 3200-meter run test was 55.323±3.238 mL/KgBB/min. The value was statistically significant (p=0.008. There was no significant difference in the physiological response in both tests, except the SpO2 parameter after the tests (p=0.021. Conclusions: There is a significant difference in VO2 max prediction between 12 minutes and 3200 meter run test. No significant difference was found in the physiological response in both tests, except the SpO2 parameter.

  18. Microwave-Assisted Solvothermal Synthesis of VO2 Hollow Spheres and Their Conversion into V2O5 Hollow Spheres with Improved Lithium Storage Capability.

    Science.gov (United States)

    Pan, Jing; Zhong, Li; Li, Ming; Luo, Yuanyuan; Li, Guanghai

    2016-01-22

    Monodispersed hierarchically structured V2O5 hollow spheres were successfully obtained from orthorhombic VO2 hollow spheres, which are in turn synthesized by a simple template-free microwave-assisted solvothermal method. The structural evolution of VO2 hollow spheres has been studied and explained by a chemically induced self-transformation process. The reaction time and water content in the reaction solution have a great influence on the morphology and phase structure of the resulting products in the solvothermal reaction. The diameter of the VO2 hollow spheres can be regulated simply by changing vanadium ion content in the reaction solution. The VO2 hollow spheres can be transformed into V2O5 hollow spheres with nearly no morphological change by annealing in air. The nanorods composed of V2O5 hollow spheres have an average length of about 70 nm and width of about 19 nm. When used as a cathode material for lithium-ion batteries, the V2O5 hollow spheres display a diameter-dependent electrochemical performance, and the 440 nm hollow spheres show the highest specific discharge capacity of 377.5 mAhg(-1) at a current density of 50 mAg(-1) , and are better than the corresponding solid spheres and nanorod assemblies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Raman spectroscopy of WO3 nano-wires and thermo-chromism study of VO2 belts produced by ultrasonic spray and laser pyrolysis techniques

    CSIR Research Space (South Africa)

    Mwakikunga, BW

    2008-01-01

    Full Text Available . This was carried out us- ing MathmatcaTM. Electrical resistances of the VO2 (R) nanobelts (NBs) were measured at different points on the sample using a digital multi-meter and heated base coupled with a tem- perature controller. The Varian Cary 500...

  20. Use of ZnO as antireflective, protective, antibacterial, and biocompatible multifunction nanolayer of thermochromic VO2 nanofilm for intelligent windows

    Science.gov (United States)

    Zhou, Huaijuan; Li, Jinhua; Bao, Shanhu; Li, Jian; Liu, Xuanyong; Jin, Ping

    2016-02-01

    A multifunctional VO2/ZnO bilayer film is designed and deposited by magnetron sputtering apparatus. The integration of the antireflective, antioxidative and anti-corrosion functions, and antibacterial performance makes the heterostructure film a promising candidate in the energy-saving smart window. The ZnO thin film as the antireflection layer can markedly boost the solar regulation efficiency (ΔTsol) from 7.7% to 12.2% and possesses excellent luminous transmittance (Tlum-L = 50.3%) in the low-temperature semiconductor phase. The ZnO layer as the protection barrier can not only protect VO2 thin film from oxidation to much toxic V2O5, but also decrease the release of V ions. Besides, the synergistic effect of releasing killing by Zn2+ ions and contact killing by ZnO NPs makes ZnO thin film an outstanding antibacterial coating. In terms of the biological safety, ZnO coating with appropriate film thickness can effectively attenuate the cytotoxicity of VO2 on human HIBEpiC cells. We hope this work can provide new insights for better designing of novel multifunctional VO2-based intelligent energy-saving windows.

  1. Modification of Mott phase transition characteristics in VO2@TiO2 core/shell nanostructures by misfit-strained heteroepitaxy.

    Science.gov (United States)

    Li, Yamei; Ji, Shidong; Gao, Yanfeng; Luo, Hongjie; Jin, Ping

    2013-07-24

    Vanadium dioxide (VO2) is a key material for thermochromic smart windows that can respond to environmental temperature and modulate near-infrared irradiation by changing from a transparent state at low temperature to a more reflective state at high temperature, while maintaining visible transmittance. Here, we demonstrate for the first time that the Mott phase transition characteristics in VO2 nanoparticles can be remarkably modified by misfit strains occurring at the epitaxial interface between VO2 and the anatase TiO2 of VO2/TiO2 core-shell particles. The heteroepitaxial growth of the as-synthesized particles followed an unprecedented orientation relationship, and an epitaxial growth mechanism is proposed to explain this behavior. A relatively small theoretical coherent misfit (3-11%) and a moderate heating rate (20 °C·min(-1)) in the preparation of the core-shell structure were critically important from the thermodynamic and kinetic perspectives, respectively. The misfit-induced interfacial strain along the uniaxial cR axis increased the transition temperatures, especially on the cooling portion of the heating-cooling cycle, leading to a notably reduced transition hysteresis loop width (from 23.5 to 12.0 °C). Moreover, the optical band gap was also engineered by the interfacial effect. Such a reduced hysteresis showed a benefit for enhancing a rapid response for energy saving thermochromic smart windows.

  2. Improved VO2max and time trial performance with more high aerobic intensity interval training and reduced training volume: a case study on an elite national cyclist.

    Science.gov (United States)

    Støren, Øyvind; Bratland-Sanda, Solfrid; Haave, Marius; Helgerud, Jan

    2012-10-01

    The present study investigated to what extent more high aerobic intensity interval training (HAIT) and reduced training volume would influence maximal oxygen uptake (VO2max) and time trial (TT) performance in an elite national cyclist in the preseason period. The cyclist was tested for VO2max, cycling economy (C(c)), and TT performance on an ergometer cycle during 1 year. Training was continuously logged using heart rate monitor during the entire period. Total monthly training volume was reduced in the 2011 preseason compared with the 2010 preseason, and 2 HAIT blocks (14 sessions in 9 days and 15 sessions in 10 days) were performed as running. Between the HAIT blocks, 3 HAIT sessions per week were performed as cycling. From November 2010 to February 2011, the cyclist reduced total average monthly training volume by 18% and cycling training volume by 60%. The amount of training at 90-95% HRpeak increased by 41%. VO2max increased by 10.3% on ergometer cycle. TT performance improved by 14.9%. C(c) did not change. In conclusion, preseason reduced total training volume but increased amount of HAIT improved VO2max and TT performance without any changes in C(c). These improvements on cycling appeared despite that the HAIT blocks were performed as running. Reduced training time, and training transfer from running into improved cycling form, may be beneficial for cyclists living in cold climate areas.

  3. Room-temperature subnanosecond waveguide lasers in Nd:YVO4 Q-switched by phase-change VO2: A comparison with 2D materials

    Science.gov (United States)

    Nie, Weijie; Li, Rang; Cheng, Chen; Chen, Yanxue; Lu, Qingming; Romero, Carolina; Vázquez de Aldana, Javier R.; Hao, Xiaotao; Chen, Feng

    2017-04-01

    We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66.7 mW. To compare the Q-switched laser performances by VO2 saturable absorber with those based on two-dimensional materials, the 1064-nm laser pulses have been realized in the same waveguide platform with either graphene or transition metal dichalcogenide (in this work, WS2) coated mirror. The results on 2D material Q-switched waveguide lasers have shown that the shortest pulses are with 22-ns duration, whilst the maximum output average powers reach ~161.9 mW. This work shows the obvious difference on the lasing properties based on phase-change material and 2D materials, and suggests potential applications of VO2 as low-cost saturable absorber for subnanosecond laser generation.

  4. KONTRIBUSI TINGGI BADAN, RENTANG LENGAN, KEKUATAN OTOT LENGAN DAN OTOT TUNGKAI, SERTA VO2 MAX TERHADAP PRESTASI MENDAYUNG MESIN ROWING JARAK 2000 METER PADA ATLET DAYUNG NASIONAL

    Directory of Open Access Journals (Sweden)

    Mei Sandy Wahyuningsih

    2015-12-01

    Full Text Available The problem in this research were 1 Is there a height contributes to achievement of rowing machine rowing 2000 meters distance. 2 Is there a arms lenght contribution to the achievement of a rowing machine rowing 3 Is there an arm muscle strength contributes to the achievement of rowing 4 Is there a leg muscle strength contributes to the achievement of a rowing machine rowing 5 are there any VO2max contribution to the achievement Max rowing machine rowing 6 which one has contribution greater than height, arm length, arm muscle strength and leg muscles, as well as VO2 Max to achievement rowing machine rowing The results of data analysis showed that height contributes to achievement of rowing machine rowing 38.1%. Contribution to the achievement of the arm lenght rowing to machine rowing 35.9%. Contribution to the achievement of the strength of the arm muscles rowing machine rowing 40.4%. Leg muscle strength contributes to the achievement of a rowing machine rowing 45.3%. Contributions VO2Max the achievement of rowing machine rowing 51.5%. contribution of height, arm length, arm muscle strength and leg muscles as well VO 2Max the distance rowing machine rowing achievements in 2000 by 66.6%.

  5. Speeding of pulmonary VO2 on-kinetics by light-to-moderate-intensity aerobic exercise training in chronic heart failure: clinical and pathophysiological correlates.

    Science.gov (United States)

    Mezzani, Alessandro; Grassi, Bruno; Jones, Andrew M; Giordano, Andrea; Corrà, Ugo; Porcelli, Simone; Della Bella, Silvia; Taddeo, Adriano; Giannuzzi, Pantaleo

    2013-09-01

    Pulmonary VO2 on-kinetics during light-to-moderate-intensity constant-work-rate exercise, an experimental model mirroring energetic transitions during daily activities, has been shown to speed up with aerobic exercise training (AET) in normal subjects, but scant data are available in chronic heart failure (CHF). Thirty CHF patients were randomized to 3 months of light-to-moderate-intensity AET (CHF-AET) or control (CHF-C). Baseline and end-protocol evaluations included i) one incremental cardiopulmonary exercise test with near infrared spectroscopy analysis of peak deoxygenated hemoglobin+myoglobin concentration changes (Δ[deoxy(Hb+Mb)]) in vastus lateralis muscle, ii) 8 light-to-moderate-intensity constant-work-rate exercise tests for VO2 on-kinetics phase I duration, phase II τ, and mean response time (MRT) assessment, and iii) circulating endothelial progenitor cell (EPC) measurement. Reference values were obtained in 7 age-matched normals (N). At end-protocol, phase I duration, phase II τ, and MRT were significantly reduced (-12%, -22%, and -19%, respectively) and peak VO2, peak Δ[deoxy(Hb+Mb)], and EPCs increased (9%, 20%, and 98%, respectively) in CHF-AET, but not in CHF-C. Peak Δ[deoxy(Hb+Mb)] and EPCs relative increase correlated significantly to that of peak VO2 (r=0.61 and 0.64, respectively, pLight-to-moderate-intensity AET determined a near-normalization of pulmonary VO2 on-kinetics in CHF patients. Such a marked plasticity has important implications for AET intensity prescription, especially in patients more functionally limited and with high exercise-related risk. The AET-induced simultaneous improvement of phase I and phase II, associated with an increase of peak peripheral oxygen extraction and EPCs, supports microcirculatory O2 delivery impairment as a key factor determining exercise intolerance in CHF. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  6. Developing new VO2max prediction models from maximal, submaximal and questionnaire variables using support vector machines combined with feature selection.

    Science.gov (United States)

    Abut, Fatih; Akay, Mehmet Fatih; George, James

    2016-12-01

    Maximal oxygen uptake (VO2max) is an essential part of health and physical fitness, and refers to the highest rate of oxygen consumption an individual can attain during exhaustive exercise. In this study, for the first time in the literature, we combine the triple of maximal, submaximal and questionnaire variables to propose new VO2max prediction models using Support Vector Machines (SVM's) combined with the Relief-F feature selector to predict and reveal the distinct predictors of VO2max. For comparison purposes, hybrid models based on double combinations of maximal, submaximal and questionnaire variables have also been developed. By utilizing 10-fold cross-validation, the performance of the models has been calculated using multiple correlation coefficient (R) and root mean square error (RMSE). The results show that the best values of R and RMSE, with 0.94 and 2.92mLkg-1min-1 respectively, have been obtained by combining the triple of relevantly identified maximal, submaximal and questionnaire variables. Compared with the results of the rest of hybrid models in this study and the other prediction models in literature, the reported values of R and RMSE have been found to be considerably more accurate. The predictor variables gender, age, maximal heart rate (MX-HR), submaximal ending speed (SM-ES) of the treadmill and Perceived Functional Ability (Q-PFA) questionnaire have been found to be the most relevant variables in predicting VO2max. The results have also been compared with that of Multilayer Perceptron (MLP) and Tree Boost (TB), and it is seen that SVM significantly outperforms other regression methods for prediction of VO2max. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Effects of acute 60 and 80% VO2max bouts of aerobic exercise on state anxiety of women of different age groups across time.

    Science.gov (United States)

    Cox, Richard H; Thomas, Tom R; Hinton, Pam S; Donahue, Owen M

    2004-06-01

    The purpose of this investigation was to study the effects of an acute bout of aerobic exercise on state anxiety of women while controlling for iron status (hemoglobin and serum ferritin). Participants were 24 active women, ages 18-20 years (n = 12) and 35-45 years (n = 12). In addition to a nonexercise control condition, participants completed one exercise bout at 60% maximal oxygen uptake (VO2max) and one at 80% VO2max. Each exercise session consisted of a 33-min bout in which participants exercised at their target intensities for a 20-min segment. Immediately before each exercise trial, participants were given the Spielberger State Anxiety Inventory (SAI). The SAI was again administered immediately following the exercise session and at 30, 60, and 90 min postexercise. Data were analyzed using an Age x Intensity x Time (2 x 3 x 5) repeated measures analysis of covariance (ANCOVA) with iron status serving as the covariate. The ANCOVA on state anxiety yielded significant effects for time (p Age interaction (p = .04, eta2(p) = .15). All three exercise conditions (including control) showed a decline in state anxiety across time, but the 80% VO2max condition showed a sharper decline. Intensity of exercise conditions did not differ in state anxiety at baseline or immediately after exercise, but a difference favoring the 80% VO2max condition over the control condition emerged at 30 min postexercise. After controlling for iron status, older women who exercised at 80% VO2max exhibited lower SAI scores compared to the control condition.

  8. Effects of Low-Intensity Cycle Training with Restricted Leg Blood Flow on Thigh Muscle Volume and VO2MAX in Young Men.

    Science.gov (United States)

    Abe, Takashi; Fujita, Satoshi; Nakajima, Toshiaki; Sakamaki, Mikako; Ozaki, Hayao; Ogasawara, Riki; Sugaya, Masato; Kudo, Maiko; Kurano, Miwa; Yasuda, Tomohiro; Sato, Yoshiaki; Ohshima, Hiroshi; Mukai, Chiaki; Ishii, Naokata

    2010-01-01

    Concurrent improvements in aerobic capacity and muscle hypertrophy in response to a single mode of training have not been reported. We examined the effects of low-intensity cycle exercise training with and without blood flow restriction (BFR) on muscle size and maximum oxygen uptake (VO2max). A group of 19 young men (mean age ± SD: 23.0 ± 1.7 years) were allocated randomly into either a BFR-training group (n=9, BFR-training) or a non-BFR control training group (n=10, CON-training), both of which trained 3 days/wk for 8 wk. Training intensity and duration were 40% of VO2max and 15 min for the BFR-training group and 40% of VO2max and 45 min for the CON-training group. MRI-measured thigh and quadriceps muscle cross-sectional area and muscle volume increased by 3.4-5.1% (P training group. There was no change in muscle size (~0.6%) and strength (~1.4%) in the CON-training group. Significant improvements in VO2max (6.4%) and exercise time until exhaustion (15.4%) were observed in the BFR-training group (p training group (-0.1 and 3. 9%, respectively). The results suggest that low-intensity, short-duration cycling exercise combined with BFR improves both muscle hypertrophy and aerobic capacity concurrently in young men. Key pointsConcurrent improvements in aerobic capacity and muscle hypertrophy in response to a single mode of training have not been reported.In the present study, low-intensity (40% of VO2max) cycle training with BFR can elicit concurrent improvement in muscle hypertrophy and aerobic capacity.

  9. Dynamic phase coexistence and non-Gaussian resistance fluctuations in VO2 near the metal-insulator transition

    Science.gov (United States)

    Samanta, Sudeshna; Raychaudhuri, A. K.; Zhong, Xing; Gupta, A.

    2015-11-01

    We have carried out an extensive investigation on the resistance fluctuations (noise) in an epitaxial thin film of VO2 encompassing the metal-insulator transition (MIT) region to investigate the dynamic phase coexistence of metal and insulating phases. Both flicker noise as well as the Nyquist noise (thermal noise) were measured. The experiments showed that flicker noise, which has a 1 /f spectral power dependence, evolves with temperature in the transition region following the evolution of the phase fractions and is governed by activated kinetics. Importantly, closer to the insulating end of the transition, when the metallic phase fraction is low, the magnitude of the noise shows an anomaly and a strong non-Gaussian component of noise develops. In this region, the local electron temperature (as measured through the Nyquist noise thermometry) shows a deviation from the equilibrium bath temperature. It is proposed that this behavior arises due to current crowding where a substantial amount of the current is carried through well separated small metallic islands leading to a dynamic correlated current path redistribution and an enhanced effective local current density. This leads to a non-Gaussian component to the resistance fluctuation and an associated local deviation of the electron temperature from the bath. Our experiment establishes that phase coexistence leads to a strong inhomogeneity in the region of MIT that makes the current transport strongly inhomogeneous and correlated.

  10. Lvad pump speed increase is associated with increased peak exercise cardiac output and vo2, postponed anaerobic threshold and improved ventilatory efficiency.

    Science.gov (United States)

    Vignati, Carlo; Apostolo, Anna; Cattadori, Gaia; Farina, Stefania; Del Torto, Alberico; Scuri, Silvia; Gerosa, Gino; Bottio, Tomaso; Tarzia, Vincenzo; Bejko, Jonida; Sisillo, Erminio; Nicoli, Flavia; Sciomer, Susanna; Alamanni, Francesco; Paolillo, Stefania; Agostoni, Piergiuseppe

    2017-03-01

    Peak exercise cardiac output (CO) increase is associated with an increase of peak oxygen uptake (VO2), provided that arteriovenous O2 difference [Δ(Ca-Cv)O2] does not decrease. At anaerobic threshold, VO2, is related to CO. We tested the hypothesis that, in heart failure (HF) patients with left ventricular assistance device (LVAD), an acute increase of CO obtained through changes in LVAD pump speed is associated with peak exercise and anaerobic threshold VO2 increase. Fifteen of 20 patients bearing LVAD (Jarvik 2000) enrolled in the study successfully performed peak exercise evaluation. All patients had severe HF as shown by clinical evaluation, laboratory tests, echocardiography, spirometry with alveolar-capillary diffusion, and maximal cardiopulmonary exercise testing (CPET). CPETs with non-invasive CO measurements at rest and peak exercise were done on 2days at LVAD pump speed set randomly at 2 and 4. Increasing LVAD pump speed from 2 to 4 increased CO from 3.4±0.9 to 3.8±1.0L/min (ΔCO 0.4±0.6L/min, p=0.04) and from 5.3±1.3 to 5.9±1.4L/min (ΔCO 0.6±0.7L/min, pexercise, respectively. Similarly, VO2 increased from 788±169 to 841±152mL/min (ΔVO2 52±76mL/min, p=0.01) and from 568±116 to 619±124mL/min (ΔVO2 69±96mL/min, p=0.02) at peak exercise and at anaerobic threshold, respectively. Δ(Ca-Cv)O2 did not change significantly, while ventilatory efficiency improved (VE/VCO2 slope from 39.9±5.4 to 34.9±8.3, ΔVE/VCO2 -5.0±6.4, panaerobic threshold, and improved ventilatory efficiency. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. How to Be 80 Year Old and Have a VO2max of a 35 Year Old

    Directory of Open Access Journals (Sweden)

    Trine Karlsen

    2015-01-01

    Full Text Available Background. To discuss the cardiovascular and pulmonary physiology and common risk factors of an 80-year-old man with a world record maximal oxygen uptake of 50 mL·kg−1·min−1. Methods. Case report. Results. His maximal oxygen uptake of 3.31 L·min−1, maximal heart rate of 175 beats·min−1, and maximal oxygen pulse of 19 mL·beats−1 are high. He is lean (66.6 kg and muscular (49% skeletal muscle mass. His echo parameters of mitral flow (left ventricular filling, E = 82 cm·s−1 and E/A = 1.2 were normal for 40- to 60-year-old men. Systolic and diastolic function increased adequately during exercise, with no increase in left ventricular filling pressure. He has excellent pulmonary function (FVC = 4.31 L, FEV1 = 3.41, FEV1/FVC = 0.79, and DLCO = 12.0 Si1 and normal FMD and blood volumes (5.8 L. He has a high level of daily activity (10,900 steps·day−1 and 2:51 hours·day−1 of physical activity and a lifelong history of physical activity. Conclusion. The man is in excellent cardiopulmonary fitness and is highly physically active. His cardiac and pulmonary functions are above expectations for his age, and his VO2max is comparable to that of an inactive 25-year-old and of a normal, active 35-year-old Norwegian man.

  12. How to Be 80 Year Old and Have a VO2max of a 35 Year Old.

    Science.gov (United States)

    Karlsen, Trine; Leinan, Ingeborg Megård; Bækkerud, Fredrik Hjulstad; Lundgren, Kari Margrethe; Tari, Atefe; Steinshamn, Sigurd Loe; Støylen, Asbjørn; Rognmo, Øivind

    2015-01-01

    Background. To discuss the cardiovascular and pulmonary physiology and common risk factors of an 80-year-old man with a world record maximal oxygen uptake of 50 mL·kg(-1)·min(-1). Methods. Results. His maximal oxygen uptake of 3.31 L·min(-1), maximal heart rate of 175 beats·min(-1), and maximal oxygen pulse of 19 mL·beats(-1) are high. He is lean (66.6 kg) and muscular (49% skeletal muscle mass). His echo parameters of mitral flow (left ventricular filling, E = 82 cm·s(-1) and E/A = 1.2) were normal for 40- to 60-year-old men. Systolic and diastolic function increased adequately during exercise, with no increase in left ventricular filling pressure. He has excellent pulmonary function (FVC = 4.31 L, FEV1 = 3.41, FEV1/FVC = 0.79, and DLCO = 12.0 Si(1)) and normal FMD and blood volumes (5.8 L). He has a high level of daily activity (10,900 steps·day(-1) and 2:51 hours·day(-1) of physical activity) and a lifelong history of physical activity. Conclusion. The man is in excellent cardiopulmonary fitness and is highly physically active. His cardiac and pulmonary functions are above expectations for his age, and his VO2max is comparable to that of an inactive 25-year-old and of a normal, active 35-year-old Norwegian man.

  13. Effect of VO2+ ions on the EPR and optical absorption investigations of lithium sulphate monohydrate single crystals for non linear optical applications

    Science.gov (United States)

    Juliet sheela, K.; Radha Krishnan, S.; Shanmugam, V. M.; Subramanian, P.

    2017-09-01

    Electron paramagnetic resonance (EPR) and optical absorption studies of VO2+ ions in Lithium Sulphate Monohydrate (LSMH) single crystal are carried out at room temperature. Single crystal rotations in each of the three mutually orthogonal crystalline planes, ac, ab, cb indicate three different vanadyl complexes. Three VO2+ ions of EPR spectra indicate among them, that two of them have (the intense two) entered the lattice substitutionally and the third one occupies the interstitial position. From the angular variation, the spin Hamiltonian parameters are evaluated. From the optical absorption spectrum containing four selected bands and EPR data, various bonding parameters are determined and the nature of bonding in the crystal is discussed. Also Second Harmonic Generation (SHG) studies are carried out to confirm the Non Linear Optical (NLO) properties of the given material.

  14. Arm Cycling Combined with Passive Leg Cycling Enhances VO2peakin Persons with Spinal Cord Injury Above the Sixth Thoracic Vertebra.

    Science.gov (United States)

    Tørhaug, Tom; Brurok, Berit; Hoff, Jan; Helgerud, Jan; Leivseth, Gunnar

    2018-01-01

    Objective : To test whether passive leg cycling (PLC) during arm cycling ergometry (ACE) affects peak oxygen uptake (VO 2peak ) differently in individuals with spinal cord injury (SCI) at/above the 6th thoracic vertebra (T6) and below T6. Methods: We conducted a cross-sectional study, analyzed by univariate and multivariate regression models. Between- and within-group differences were examined during (a) ACE only, (b) ACE combined with PLC (ACE-PLC), and (c) ACE combined with functional electrical stimulation cycling (FES hybrid). Fifteen SCI subjects were recruited and grouped according to injury level: at/above T6 (SCI-high, n = 8) or below T6 (SCI-low, n = 7). VO 2peak tests during ACE only, ACE-PLC, and FES hybrid were performed in random order on separate days. Results : In the SCI-high group, mean ( SD ) VO 2peak was 19% higher during ACE-PLC than during ACE only [21.0 (3.8) vs 17.7 (5.0) mL·kg -1 ·min -1 ; p = .002], while VO 2peak during FES hybrid cycling was 16% higher than during ACE-PLC [24.4 (4.1) mL·kg -1 ·min -1 ; p = .001]. No significant differences among exercise modalities were found for the SCI-low group. Conclusion : Additional training modalities (eg, PLC) during ACE facilitate exercise in SCI-high individuals, but not to the level of the FES hybrid method. Conversely, additional training modalities may not increase training load in SCI-low individuals.

  15. Effect of Change in VO2max on Daily Total Energy Expenditure in a Cohort of Norwegian Men: A Randomized Pilot Study.

    Science.gov (United States)

    Zisko, Nina; Stensvold, Dorthe; Hordnes-Slagsvold, Katrine; Rognmo, Øivind; Nauman, Javaid; Wisløff, Ulrik; Karlsen, Trine

    2015-01-01

    To investigate how a change in VO2max induced through 6 weeks of high intensity aerobic interval training affects daily total energy expenditure (TEE), active energy expenditure (AEE) and mitochondrial function in people not previously exposed to structured high intensity aerobic interval training (AIT). Thirty healthy males (39±6 yrs) not exposed to structured exercise training were randomized to either 1x4 min AIT (1-AIT), 4x4 min AIT (4-AIT), both at 90-95% maximum heart rate (HRmax) or 47 min of MCT at 70% HRmax. TEE, AEE, number of steps, active time, sedentary time, VO2max and mitochondrial function in m. vastus lateralis were measured before and after intervention. TEE increased 14% (p=0.014) and AEE increased 43% (p= 0.004) after MCT. There was no change in TEE or AEE after 1-AIT or 4-AIT, but 1-AIT had significantly lower TEE (p=0.033) and step-count (p=0.011) compared to MCT post intervention. VO2max increased 7% after 1-AIT (p= 0.004) and 9% after 4-AIT (p=0.004), with no change after MCT. No change was observed in maximal mitochondrial respiration (VMAX) or Citrate Synthase (CS) activity within or between interventions. Basal respiration (V0) increased after 1-AIT (p=0.029) and 4-AIT (p=0.022), with no significant change after MCT. AIT interventions that increase VO2max, do not stimulate subjects to increase TEE or AEE. The intensity of exercise seems to play apart, as MCT increased TEE and AEE and AIT did not. Emphasis should be placed on the importance of maintaining everyday activities when introducing structured exercise training to untrained individuals.

  16. EFFECTS OF LOW-INTENSITY CYCLE TRAINING WITH RESTRICTED LEG BLOOD FLOW ON THIGH MUSCLE VOLUME AND VO2MAX IN YOUNG MEN

    Directory of Open Access Journals (Sweden)

    Takashi Abe

    2010-09-01

    Full Text Available Concurrent improvements in aerobic capacity and muscle hypertrophy in response to a single mode of training have not been reported. We examined the effects of low-intensity cycle exercise training with and without blood flow restriction (BFR on muscle size and maximum oxygen uptake (VO2max. A group of 19 young men (mean age ± SD: 23.0 ± 1.7 years were allocated randomly into either a BFR-training group (n=9, BFR-training or a non-BFR control training group (n=10, CON-training, both of which trained 3 days/wk for 8 wk. Training intensity and duration were 40% of VO2max and 15 min for the BFR-training group and 40% of VO2max and 45 min for the CON-training group. MRI-measured thigh and quadriceps muscle cross-sectional area and muscle volume increased by 3.4-5.1% (P < 0.01 and isometric knee extension strength tended to increase by 7.7% (p < 0.10 in the BFR-training group. There was no change in muscle size (~0.6% and strength (~1.4% in the CON-training group. Significant improvements in VO2max (6.4% and exercise time until exhaustion (15.4% were observed in the BFR-training group (p < 0.05 but not in the CON-training group (-0.1 and 3. 9%, respectively. The results suggest that low-intensity, short-duration cycling exercise combined with BFR improves both muscle hypertrophy and aerobic capacity concurrently in young men.

  17. Controlled reactive HiPIMS—effective technique for low-temperature (300 °C) synthesis of VO2 films with semiconductor-to-metal transition

    Science.gov (United States)

    Vlček, J.; Kolenatý, D.; Houška, J.; Kozák, T.; Čerstvý, R.

    2017-09-01

    Reactive high-power impulse magnetron sputtering with a pulsed O2 flow control and to-substrate O2 injection into a high-density plasma in front of the sputtered vanadium target was used for low-temperature (300 °C) deposition of VO2 films with a pronounced semiconductor-to-metal transition onto conventional soda-lime glass substrates without any substrate bias voltage and without any interlayer. The depositions were performed using an unbalanced magnetron with a planar target of 50.8 mm diameter in argon-oxygen gas mixtures at the argon pressure of 1 Pa. The deposition-averaged target power density was close to 13 W cm-2 at a fixed duty cycle of 1% with a peak target power density up to 5 kW cm-2 during voltage pulses ranged from 40 µs to 100 µs. A high modulation of the transmittance at 2500 nm (between 51% and 8% at the film thickness of 88 nm) and the electrical resistivity (changed 350 times) at the transition temperature of 56-57 °C was achieved for the VO2 films synthesized using 50 µs voltage pulses when the crystallization of the thermochromic VO2(M1) phase was supported by the high-energy (up to 50 eV relative to ground potential) ions. Principles of this effective low-temperature deposition technique with a high application potential are presented.

  18. The electronic structure of the Mott insulator VO2: the strongly correlated metal state is screened by impurity band

    Science.gov (United States)

    Kim, Hyun-Tak

    A Mott insulator VO2 (3d1) has a direct gap (Δdirect ~Vdirect) of 0.6 eV and an indirect gap of Δact ~Vdirect ~ 0.15 eV coming from impurity indirect band. At Tc, Δdirect =Δact = O is satisfied and the insulator-to-metal transition (IMT) occurs. The metallic carriers near core region can be trapped when a critical onsite Coulomb Uc exists. Then, a potential energy is defined as Vg =Vdirect +Uc +Vindirect = - (2 2 3) EF (1 + e (NtotNtotntot) (1 - exp (-Δact-ΔactkB T))) +Uc kB T))) +Uc ntot) (1 - exp (-Δact-ΔactkB T))) +Uc kB T))) +Uc 3) EF (1 + e (NtotNtotntot) (1 - exp (-Δact-ΔactkB T))) +Uc kB T))) +Uc ntot) (1 - exp (-Δact-ΔactkB T))) +Uc kB T))) +Uc , where Vdirect = - (2 2 3 3) EF is the screened Coulomb pseudopotential at K = 0. Δρ =NtotNtotntot ~ 0 . 018 % ntot ~ 0 . 018 % [1] is defined as the critical doping quantity, where ntot is the carrier density in the direct band and Ntot is the carrier density in the impurity band. In Uc 2 3 3) EF case, it sustains the insulator state. However, when both Uc > (2 2 3 3) EF and Δact = 0 by excitation are satisfied, the IMT occurs in Vg >= 0. This indicates that the excitation (Δact = 0) breaks the Coulomb equilibrium (Vgsustaining Uc) in Eq. (1) ; the Coulomb energy changes from Uc to a Uswitched by the doping (excitation; Δact = 0) and the de-doping (de-excitation; Δact = 0.15 eV) of Δρ =NtotNtotntot ntot to the conduction band, by applying external parameters such as heat, pressure, doping etc. The direct band gap (semiconductor gap) in the Mott insulator smaller than that of dielectric insulators can be explained by Uc.[1] NewJ.Phys.6(2004)52.

  19. On the magnetic ordering in interleaved Fe(3 ML)/V(y ML)/Fe(2 ML)/V(y ML) superlattices

    CERN Document Server

    Eftimova, K; Hjörvarsson, B; Svedlindh, P

    2002-01-01

    The magnetic properties of superlattice films with alternating Fe thicknesses, Fe(3 ML)/V(y ML)/Fe(2 ML)/V(y ML) with 4 <= y <= 15, prepared by dc magnetron sputtering on MgO(001) substrates are studied by superconducting quantum interference device measurements. By investigating the basic magnetic observables of the films: the transition temperature T sub c , the magnetic remanence M sub r , and the saturation field H sub s , which change in a correlated manner as a function of the vanadium spacer thickness, y, we find antiferromagnetic (AFM) coupling in Fe(3 ML)/V(y ML)/Fe(2 ML)/V(y ML) for 9 < y < 11. The derived values of the spin wave parameter B and the ground state magnetic moment m sub s sub 0 also change synchronously with T sub c , M sub r , and H sub s. The peak of the AFM coupling energy per unit area, I, is estimated to be approx 0.06 mJ m sup - sup 2 using the H sub s versus y dependence.

  20. Net Locality

    DEFF Research Database (Denmark)

    de Souza e Silva, Adriana Araujo; Gordon, Eric

    Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....

  1. Net Neutrality

    DEFF Research Database (Denmark)

    Savin, Andrej

    2017-01-01

    Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else.......Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else....

  2. ML Arvutite aktsiakapital suurenes / Anne Oja

    Index Scriptorium Estoniae

    Oja, Anne, 1970-

    2006-01-01

    ML Arvutid omanik Aivar Paalberg tõstis aktsiakapitali seniselt 10 miljonilt 24 miljonile eesmärgiga tugevdada oma positsioone Eesti turul ja kasvada kiiremas tempos kui kogu turg. Diagramm: Majandusnäitajad

  3. Prediction of severe cardiovascular events by VE/VCO2 slope versus peak VO2 in systolic heart failure: a meta-analysis of the published literature.

    Science.gov (United States)

    Poggio, Rosana; Arazi, Hernán Cohen; Giorgi, Mariano; Miriuka, Santiago G

    2010-12-01

    Peak VO2 has traditionally been used for prognostic evaluation in systolic heart failure. However, in the past years, VE/VCO2 slope has been shown to be similar or even superior in many studies. We performed a systematic review and a meta-analysis of diagnostic studies of VE/VCO2 slope to assess its ability to predict cardiovascular events in systolic heart failure. We searched the published literature in PubMed and ISI Web of Science for VE/VCO2 slope in heart failure, and performed a systematic review and a meta-analysis of diagnostic studies in articles fulfilling previously established selection criteria. End points were serious cardiovascular events defined as death or the combined end point of death, ventricular assist device implantation, or heart transplant. A sub-analysis was also performed with those articles providing enough data to compare VE/VCO(2) slope prognostic ability to that of peak VO2. Four hundred ninety-one articles that are potentially relevant were identified, and 12 studies were selected based on our predefined criteria. No heterogeneity or evidence of publication bias was found. The 12 studies included a total of 2,628 patients with a mean follow-up of 31 months (95% CI 16-46 months). The combined event rate at 1 year was 11.2% (95% CI 7.8%-14.6%). Diagnostic odds ratio and area under the curve for serious cardiovascular events were 5.02 (95% CI 4.06-6.21) and 0.75 (95% CI 0.72-0.78), respectively. Six studies provided sufficient data for VE/VCO2 slope and peak VO2 comparison. Both variables showed similar performance, although VE/VCO(2) did present a trend to superiority. In this meta-analysis, VE/VCO2 slope represents a reasonable ability to predict serious cardiovascular events in systolic heart failure, and is at least as effective as peak VO2. Copyright © 2010 Mosby, Inc. All rights reserved.

  4. Influência do estado nutricional e do VO2max nos níveis de adiponectina em homens acima de 35 anos

    Directory of Open Access Journals (Sweden)

    Eduardo Camillo Martinez

    2011-06-01

    Full Text Available FUNDAMENTO: A adiponectina é considerada importante fator na patogênese das doenças cardiovasculares e metabólicas, por suas propriedades antiaterogênicas e antiinflamatórias. Poucos estudos, entretanto, sugerem a existência de relação direta entre os níveis de adiponectina e os níveis de condicionamento cardiorrespiratório e atividade física. OBJETIVO: Verificar a influência do estado nutricional e do condicionamento cardiorrespiratório nos níveis plasmáticos de adiponectina em homens adultos. MÉTODOS: Foram avaliados 250 sujeitos, homens, todos militares da ativa do Exército Brasileiro (42,6 ± 4,8 anos. Foram mensurados os níveis plasmáticos de adiponectina, massa corporal, estatura, circunferência da cintura (CC, percentual de gordura por pesagem hidrostática e VO2max por ergoespirometria. Um questionário foi utilizado para obter as características do treinamento físico realizado pelos sujeitos. RESULTADOS: Na amostra, 121 (48% sujeitos apresentaram sobrepeso e 36 (14% eram obesos. Ainda, 66 sujeitos (27% apresentaram percentual de gordura maior que 25% e 26.7% apresentaram CC > 94 cm. Sujeitos com sobrepeso e obesidade apresentaram valores significativamente menores de adiponectina em relação aqueles com estado nutricional normal. Sujeitos no mais alto tercil de VO2max apresentaram níveis de adiponectina mais altos que os demais. Os níveis de adiponectina estiveram positivamente correlacionados com o tempo total de treinamento físico semanal e com o VO2max e inversamente correlacionados com os valores de massa corporal, IMC e CC. A correlação dos níveis de adiponectina e do VO2max não permaneceu significante após controlada pelo IMC e CC. CONCLUSÃO: Sujeitos com melhor condicionamento cardiorrespiratório e com estado nutricional normal parecem apresentar níveis mais saudáveis de adiponectina.

  5. Determinación del Vo2max en un grupo de adultos que practican natación recreativa en la ciudad de Tres Arroyos

    OpenAIRE

    Miranda, Diego

    2015-01-01

    El presente trabajo se encuadra dentro de la realidad de un grupo de personas que practican Natación de forma recreativa en la ciudad de Tres Arroyos. El tema que rige la investigación de la tesis se basa en la determinación del Consumo máximo de oxígeno (Vo2 max) de los nadadores a través de pruebas indirectas1, test máximo incremental de Lavoie realizadas en la piscina. Además se tomaron otros test en donde las variables fueron tiempo y distancia a máxima intensidad, estos fu...

  6. KONTRIBUSI TINGGI BADAN, RENTANG LENGAN, KEKUATAN OTOT LENGAN DAN OTOT TUNGKAI, SERTA VO2 MAX TERHADAP PRESTASI MENDAYUNG MESIN ROWING JARAK 2000 METER PADA ATLET DAYUNG NASIONAL

    OpenAIRE

    Mei Sandy Wahyuningsih; Agus Raharjo

    2015-01-01

    The problem in this research were 1) Is there a height contributes to achievement of rowing machine rowing 2000 meters distance. 2) Is there a arms lenght contribution to the achievement of a rowing machine rowing 3) Is there an arm muscle strength contributes to the achievement of rowing 4) Is there a leg muscle strength contributes to the achievement of a rowing machine rowing 5) are there any VO2max contribution to the achievement Max rowing machine rowing 6) which one has contribution gre...

  7. An Action Compiler Targeting Standard ML

    DEFF Research Database (Denmark)

    Iversen, Jørgen

    2005-01-01

    We present an action compiler that can be used in connection with an action semantics based compiler generator. Our action compiler produces code with faster execution times than code produced by other action compilers, and for some non-trivial test examples it is only a factor two slower than...... the code produced by the Gnu C Compiler. Targeting Standard ML makes the description of the code generation simple and easy to implement. The action compiler has been tested on a description of the Core of Standard ML and a subset of C....

  8. Spectroscopic and optical properties of the VO2+ ion doped TeO2-TiO2-ZnO-Nb2O5 glass system

    Science.gov (United States)

    Swapna; Upender, G.; Sreenivasulu, V.; Prasad, M.

    2016-04-01

    Studies such as optical absorption, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Electron paramagnetic resonance (EPR) spectroscopy and Differential scanning calorimetry (DSC) were carried out on VO2+ ion doped TeO2-TiO2-ZnO-Nb2O5 glass system. Raman and FTIR spectra of the glasses revealed the presence of [TeO3], [TeO4] and [NbO6] structural units in the glass network. The Urbach energy (Δ E), cut-off wavelength (λ c ), optical band gap ( E opt ), optical basicity (Λ) and electron polarizability ( α) of the glasses were determined from optical absorption studies. The density ( ρ), molar volume ( V m ), oxygen molar volume ( V o ) and refractive index ( n) were also measured. Spin-Hamiltonian parameters were calculated from the EPR studies. When Nb2O5 was increased at the expense of ZnO, the density, optical band gap and Urbach energy of the glasses increased, and the electronic polarizability and optical basicity decreased. The EPR spectra clearly showed that vanadium was in the glass as VO2+ and occupied octahedral sites with tetrahedral compression. Spin-Hamiltonian parameters g‖ and g⊥ decreased as Nb2O5 content increased in the glass. The glass transition temperature ( T g ) also increased with increasing Nb2O5 content in the glass.

  9. Production of VO2 M1 and M2 nanoparticles and composites and the influence of the substrate on the structural phase transition.

    Science.gov (United States)

    Booth, Jamie M; Casey, Philip S

    2009-09-01

    A two-step, high-purity, high-yield synthesis of nanoparticulate vanadium dioxide, which has a greater than 10-fold potential cost reduction is reported. This consists of a short reflux of V2O5 with aspartic acid, followed by calcination at 600 degrees C or above. The particles produced have a mean diameter of approximately 90 nm with phase change characteristics of transition temperature and enthalpy that compare favorably with a commercial standard. In cases where the reduction reaction has progressed too far and a mixture of vanadium(III) and -(IV) is formed, redispersion and aging of the particulate product in water preferentially oxidizes the vanadium(III) component to vanadium(IV), thus allowing a versatile route to achieving a high-purity material. The synthesis was also used to deposit high-purity phases of VO2 onto the surfaces of other particles, and significant differences in the structural phase transition behavior and even the crystal structure were found for deposited samples. The data suggest that substrate properties may affect the characteristics of the structural phase transition, and this has significant implications for measurements on, and applications of, deposited VO2 layers and films.

  10. Supervised physical exercise improves VO2max, quality of life, and health in early stage breast cancer patients: a randomized controlled trial.

    Science.gov (United States)

    Casla, Soraya; López-Tarruella, Sara; Jerez, Yolanda; Marquez-Rodas, Iván; Galvão, Daniel A; Newton, Robert U; Cubedo, Ricardo; Calvo, Isabel; Sampedro, Javier; Barakat, Rubén; Martín, Miguel

    2015-09-01

    Breast cancer patients suffer impairment in cardiorespiratory fitness after treatment for primary disease, affecting patients' health and survival. The aim of this study was to evaluate the ability of a pragmatic exercise intervention to improve cardiorespiratory fitness of breast cancer patients after primary treatment. Between February 2013 and December 2014, 94 women with early stage (I-III) breast cancer, 1-36 months post-chemotherapy, and radiotherapy were randomly assigned to an intervention program (EX) combining supervised aerobic and resistance exercise (n = 44) or usual care (CON) (n = 45) for 12 weeks. Primary study endpoint was VO2max. Secondary endpoints were muscle strength, shoulder range of motion, body composition, and quality of life (QoL). Assessments were undertaken at baseline, 12-week, and 6-month follow-ups. Eighty-nine patients aged 29-69 years were assessed at baseline and 12 weeks. The EX group showed significant improvements in VO2max, muscle strength, percent fat, and lean mass (p ≤ 0.001 in all cases) and QoL compared with usual care (CON). Apart from body composition, improvements were maintained for the EX at 6-month follow-up. There were no adverse events during the testing or exercise intervention program. A combined exercise intervention produced considerable improvement in cardiorespiratory fitness, physical function, and quality of life in breast cancer patients previously treated with chemotherapy and radiation therapy. Importantly, most of these benefits were maintained 6 months after ceasing the supervised exercise intervention.

  11. Velocity at V(.)O(2 max) and peak treadmill velocity are not influenced within or across the phases of the menstrual cycle.

    Science.gov (United States)

    Burrows, M; Bird, S R

    2005-03-01

    Velocity at VO(2 max) (vV(.)O(2 max)) and peak treadmill velocity (PTV) are variables highly predictive of endurance performance. However, how these variables are affected by the menstrual cycle is unknown. The aim of this study was to assess the effect of the menstrual cycle on vV(.)O(2 max) and PTV. Ten, female runners were studied across three menstrual cycles. Training, menstrual history and mood states were assessed for 2 months, with daily salivary samples taken to detect menstrual phases. During the third menstrual cycle, participants completed a maximal test to determine V(.)O(2 max), vV(.)O(2 max) and PTV in the early follicular phase, late follicular phase, early luteal phase, late luteal phase and menses. Progesterone increased at the onset of the luteal phase [mean (SEM); 490 (73.6) pmol l(-1)] compared to the follicular phase [344.6 (59.7) pmol l(-1)). No significant differences in the psychological mood states between the phases of the menstrual cycle were found (P>0.05). No significant differences in vV(.)O(2 max) (P=0.611), or PTV (P=0.472) were found between the phases of the menstrual cycle. Thus, vV(.)O(2 max) and PTV are not affected by the monthly menstrual cycle in female endurance runners.

  12. Bioenergetics and neuromuscular determinants of the time to exhaustion at velocity corresponding to VO2max in recreational long-distance runners.

    Science.gov (United States)

    Bertuzzi, Romulo; Bueno, Salomão; Pasqua, Leonardo A; Acquesta, Fernanda M; Batista, Mauro B; Roschel, Hamilton; Kiss, Maria A P D M; Serrão, Júlio C; Tricoli, Valmor; Ugrinowitsch, Carlos

    2012-08-01

    The purpose of this study was to investigate the main bioenergetics and neuromuscular determinants of the time to exhaustion (T(lim)) at the velocity corresponding to maximal oxygen uptake in recreational long-distance runners. Twenty runners performed the following tests on 5 different days: (a) maximal incremental treadmill test, (b) 2 submaximal tests to determine running economy and vertical stiffness, (c) exhaustive test to measured the T(lim), (d) maximum dynamic strength test, and (e) muscle power production test. Aerobic and anaerobic energy contributions during the T(lim) test were also estimated. The stepwise multiple regression method selected 3 independent variables to explain T(lim) variance. Total energy production explained 84.1% of the shared variance (p = 0.001), whereas peak oxygen uptake (V(O2)peak) measured during T(lim)and lower limb muscle power ability accounted for the additional 10% of the shared variance (p = 0.014). These data suggest that the total energy production, V(O2)peak, and lower limb muscle power ability are the main physiological and neuromuscular determinants of T(lim)in recreational long-distance runners.

  13. HEP meets ML award talk : XGBoost

    CERN Multimedia

    CERN. Geneva; CHEN, Tianqi

    2015-01-01

    Tianqi Chen and Tong He (team crowwork) have provided very early in the challenge to all participants XGBoost (for eXtreme Gradient Boosted). It is a parallelised software to train boost decision trees, which has been effectively used by many participants to the challenge. For this, they have won the "HEP meets ML" award which is the invitation to CERN happening today.

  14. RESTful NET

    CERN Document Server

    Flanders, Jon

    2008-01-01

    RESTful .NET is the first book that teaches Windows developers to build RESTful web services using the latest Microsoft tools. Written by Windows Communication Foundation (WFC) expert Jon Flanders, this hands-on tutorial demonstrates how you can use WCF and other components of the .NET 3.5 Framework to build, deploy and use REST-based web services in a variety of application scenarios. RESTful architecture offers a simpler approach to building web services than SOAP, SOA, and the cumbersome WS- stack. And WCF has proven to be a flexible technology for building distributed systems not necessa

  15. Sex differences in the effects of 12 weeks sprint interval training on body fat mass and the rates of fatty acid oxidation and VO2max during exercise.

    Science.gov (United States)

    Bagley, Liam; Slevin, Mark; Bradburn, Steven; Liu, Donghui; Murgatroyd, Chris; Morrissey, George; Carroll, Michael; Piasecki, Mathew; Gilmore, William S; McPhee, Jamie S

    2016-01-01

    The purpose of this study was to examine whether very short duration, very high intensity sprint interval training (SIT) leads to loss of body fat mass in association with improvements to VO2max and fatty acid oxidation, and to assess the extent of sex dimorphism in these physiological responses. A total of 24 men and 17 women (mean (SEM) age: 39 (±2) years; body mass index 24.6 (0.6)) completed measurements of the maximal rate of oxygen uptake (VO2max) and fatty acid oxidation (FATmax). Body fat and lean mass were measured by dual emission x-ray absorptiometry, and fasting blood lipid, glucose and insulin profiles were assessed before and after training. SIT consisted of 4×20 s sprints on a cycle ergometer at approximately 175% VO2max, three times per week for 12 weeks. Fat mass decreased by 1.0 kg, although men lost statistically significantly more fat than women both when expressed in Kg and as % body fat. VO2max increased by around 9%, but women improved VO2max significantly more than men. FATmax improved by around 13%, but fasting plasma glucose, insulin, total triglyceride, total cholesterol and high-density lipoprotein (HDL) did not change after training, while low-density lipoprotein decreased by 8% (p=0.028) and the HDL:Total Cholesterol ratio improved by 6%. There were no sex differences in these metabolic responses to training. These results show lower body fat %, and higher rates of fatty acid oxidation and VO2max after 12 weeks of training for just 4 min per week. Notably, women improved VO2max more than men, while men lost more fat than women.

  16. Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials.

    Science.gov (United States)

    Milanović, Zoran; Sporiš, Goran; Weston, Matthew

    2015-10-01

    Enhancing cardiovascular fitness can lead to substantial health benefits. High-intensity interval training (HIT) is an efficient way to develop cardiovascular fitness, yet comparisons between this type of training and traditional endurance training are equivocal. Our objective was to meta-analyse the effects of endurance training and HIT on the maximal oxygen consumption (VO2max) of healthy, young to middle-aged adults. Six electronic databases were searched (MEDLINE, PubMed, SPORTDiscus, Web of Science, CINAHL and Google Scholar) for original research articles. A search was conducted and search terms included 'high intensity', 'HIT', 'sprint interval training', 'endurance training', 'peak oxygen uptake', and 'VO2max'. Inclusion criteria were controlled trials, healthy adults aged 18-45 years, training duration ≥2 weeks, VO2max assessed pre- and post-training. Twenty-eight studies met the inclusion criteria and were included in the meta-analysis. This resulted in 723 participants with a mean ± standard deviation (SD) age and initial fitness of 25.1 ± 5 years and 40.8 ± 7.9 mL·kg(-1)·min(-1), respectively. We made probabilistic magnitude-based inferences for meta-analysed effects based on standardised thresholds for small, moderate and large changes (0.2, 0.6 and 1.2, respectively) derived from between-subject SDs for baseline VO2max. The meta-analysed effect of endurance training on VO2max was a possibly large beneficial effect (4.9 mL·kg(-1)·min(-1); 95 % confidence limits ±1.4 mL·kg(-1)·min(-1)), when compared with no-exercise controls. A possibly moderate additional increase was observed for typically younger subjects (2.4 mL·kg(-1)·min(-1); ±2.1 mL·kg(-1)·min(-1)) and interventions of longer duration (2.2 mL·kg(-1)·min(-1); ±3.0 mL·kg(-1)·min(-1)), and a small additional improvement for subjects with lower baseline fitness (1.4 mL·kg(-1)·min(-1); ±2.0 mL·kg(-1)·min(-1)). When compared with no-exercise controls

  17. Petri Nets

    Indian Academy of Sciences (India)

    Associate Professor of. Computer Science and. Automation at the Indian. Institute of Science,. Bangalore. His research interests are broadly in the areas of stochastic modeling and scheduling methodologies for future factories; and object oriented modeling. GENERAL I ARTICLE. Petri Nets. 1. Overview and Foundations.

  18. Petri Nets

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 8. Petri Nets - Overview and Foundations. Y Narahari. General Article Volume 4 Issue 8 August 1999 pp ... Author Affiliations. Y Narahari1. Department ot Computer Science and Automation, Indian Institute of Science, Bangalore 560 012, India.

  19. The effects of modified exponential tapering technique on perceived exertion, heart rate, time trial performance, VO2max and power output among highly trained junior cyclists.

    Science.gov (United States)

    Ishak, Asmadi; Hashim, Hairul A; Krasilshchikov, Oleksandr

    2016-09-01

    The present study investigated the effects of a 2-week modified exponential taper on physiological adaptation and time trial performance among junior cyclists. Participants (N.=27) with the mean age of 16.95±0.8 years, height of 165.6±6.1 cm and weight of 54.19±8.1 kg were matched into either modified exponential taper (N.=7), normal exponential taper (N.=7), or control (N.=7) groups using their initial VO2max values. Both experimental groups followed a 12-week progressive endurance training program and subsequently, a 2-week tapering phase. A simulated 20-km time trial performance along with VO2max, power output, heart rate and rating of perceived exertion were measured at baseline, pre and post-taper. One way ANOVA was used to analyze the difference between groups before the start of the intervention while mixed factorial ANOVA was used to analyze the difference between groups across measurement sessions. When homogeneity assumption was violated, the Greenhouse-Geisser Value was used for the corrected values of the degrees of freedom for the within subject factor the analysis. Significant interactions between experimental groups and testing sessions were found in VO2max (F=6.67, df=4, P<0.05), power output (F=5.02, df=4, P<0.05), heart rate (F=10.87, df=2.51, P<0.05) rating of perceived exertion (F=13.04, df=4, P<0.05) and 20KM time trial (F=4.64, df=2.63, P<0.05). Post-hoc analysis revealed that both types of taper exhibited positive effects compared to the non-taper condition in the measured performance markers at post-taper while no different were found between the two taper groups. It was concluded that both taper protocols successfully inducing physiological adaptations among the junior cyclists by reducing the volume and maintaining the intensity of training.

  20. Relationship between running kinematic changes and time limit at vVO2max. DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n4p428

    Directory of Open Access Journals (Sweden)

    Sebastião Iberes Lopes Melo

    2012-07-01

    Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n4p428Exhaustive running at maximal oxygen uptake velocity (vVO2max can alter running kinematic parameters and increase energy cost along the time. The aims of the present study were to compare characteristics of ankle and knee kinematics during running at vVO2max and to verify the relationship between changes in kinematic variables and time limit (Tlim. Eleven male volunteers, recreational players of team sports, performed an incremental running test until volitional exhaustion to determine vVO2max and a constant velocity test at vVO2max. Subjects were filmed continuously from the left sagittal plane at 210 Hz for further kinematic analysis. The maximal plantar flexion during swing (p<0.01 was the only variable that increased significantly from beginning to end of the run. Increase in ankle angle at contact was the only variable related to Tlim (r=0.64; p=0.035 and explained 34% of the performance in the test. These findings suggest that the individuals under study maintained a stable running style at vVO2max and that increase in plantar flexion explained the performance in this test when it was applied in non-runners.

  1. Increased steady-state VO2 and larger O2 deficit with CO2 inhalation during exercise

    DEFF Research Database (Denmark)

    Østergaard, Lars; Kjær, Kirsten; Jensen, Kurt

    2012-01-01

    Abstract Aim:  To examine whether inhalation of CO2-enriched gas would increase steady-state during exercise and enlarge O2 deficit. Methods:  Ten physically active men ( 53.7 ± 3.6 mL min−1 kg−1; ± SD) performed transitions from low-load cycling (baseline; 40 W) to work rates representing light...... (≈ 45%; 122 ± 15 W) and heavy (≈ 80%; 253 ± 29 W) exercise while inhaling normal air (air) or a CO2 mixture (4.2% CO2, 21% O2, balance N2). Gas exchange was measured with Douglas bag technique at baseline and at min 0–2, 2–3 and 5–6. Results:  Inhalation of CO2-enriched air consistently induced...... towards increased lipid oxidation (decline in R 0.12; P 2 min of exercise were not significantly different whereas the increase in from min 2–3 to min 5–6 in heavy exercise was larger with CO2 than with air suggesting a greater slow component. As a result, O2 deficit was greater...

  2. Validation of a SysML based design for wireless sensor networks

    Science.gov (United States)

    Berrachedi, Amel; Rahim, Messaoud; Ioualalen, Malika; Hammad, Ahmed

    2017-07-01

    When developing complex systems, the requirement for the verification of the systems' design is one of the main challenges. Wireless Sensor Networks (WSNs) are examples of such systems. We address the problem of how WSNs must be designed to fulfil the system requirements. Using the SysML Language, we propose a Model Based System Engineering (MBSE) specification and verification methodology for designing WSNs. This methodology uses SysML to describe the WSNs requirements, structure and behaviour. Then, it translates the SysML elements to an analytic model, specifically, to a Deterministic Stochastic Petri Net. The proposed approach allows to design WSNs and study their behaviors and their energy performances.

  3. pymzML--Python module for high-throughput bioinformatics on mass spectrometry data.

    Science.gov (United States)

    Bald, Till; Barth, Johannes; Niehues, Anna; Specht, Michael; Hippler, Michael; Fufezan, Christian

    2012-04-01

    pymzML is an extension to Python that offers (i) an easy access to mass spectrometry (MS) data that allows the rapid development of tools, (ii) a very fast parser for mzML data, the standard data format in MS and (iii) a set of functions to compare or handle spectra. pymzML requires Python2.6.5+ and is fully compatible with Python3. The module is freely available on http://pymzml.github.com or pypi, is published under LGPL license and requires no additional modules to be installed. christian@fufezan.net.

  4. Investigation of phase evolution and control over phase transformation temperature and thermal hysteresis using stoichiometry and co-doping in VO2 thin films

    Science.gov (United States)

    Jaffari, G. Hassnain; Mahmood, Wardah

    2017-11-01

    Structural phase transition temperature and its associated hysteresis in VO2 have been controlled by high valent dopant induced local structural modification which acts as phase nucleation site during phase transformation. Monoclinic phase intensity loops plotted against temperature has been observed to exhibit thermal hysteresis. It is shown that the size, shape and central position of hysteresis loop depend on stoichiometry and doping concentration. Highest reduction in phase transformation temperature and thermal hysteresis width has been observed in case of W+6-Mo+6 co-doping and W+6 doping, respectively. Hence energy barrier associated with the structural phase transition has been successfully manipulated to vary Tc and hysteresis width. These findings have implications for designing the phase switching devices and smart window applications.

  5. Theoretical studies of the optical and EPR spectra for VO^{2+} in Na_3C_6H_5O_7·2H_2O single crystal

    Directory of Open Access Journals (Sweden)

    Ch.-Y. Li

    2015-06-01

    Full Text Available On the basis of the perturbation formulas for a d^1 configuration ion in a tetragonal crystal field, the three optical absorption bands and electron paramagnetic resonance (EPR parameters (g factors g_i and hyperfine structure constants A_i for i = || and ⊥, respectively of VO^{2+} in Na_3C_6H_5O_7·2H_2O (TSCD single crystals were studied using the perturbation theory method. By simulating the calculated optical and EPR spectra to the observed values, local structure parameters and negative signs of the hyperfine structure constants A_i of the octahedral (VO_6^{8-} cluster in TSCD single crystal can be obtained.

  6. Self Assembly and Properties of C:WO3 Nano-Platelets and C:VO2/V2O5 Triangular Capsules Produced by Laser Solution Photolysis

    Directory of Open Access Journals (Sweden)

    Sideras-Haddad E

    2009-01-01

    Full Text Available Abstract Laser photolysis of WCl6 in ethanol and a specific mixture of V2O5 and VCl3 in ethanol lead to carbon modified vanadium and tungsten oxides with interesting properties. The presence of graphene’s aromatic rings (from the vibrational frequency of 1,600 cm−1 together with C–C bonding of carbon (from the Raman shift of 1,124 cm−1 present unique optical, vibrational, electronic and structural properties of the intended tungsten trioxide and vanadium dioxide materials. The morphology of these samples shows nano-platelets in WO x samples and, in VO x samples, encapsulated spherical quantum dots in conjunction with fullerenes of VO x . Conductivity studies revealed that the VO2/V2O5 nanostructures are more sensitive to Cl than to the presence of ethanol, whereas the C:WO3 nano-platelets are more sensitive to ethanol than atomic C.

  7. Structural, thermal and optical properties of TeO2-ZnO-CdO-BaO glasses doped with VO(2+).

    Science.gov (United States)

    Sreenivasulu, V; Upender, G; Chandra Mouli, V; Prasad, M

    2015-09-05

    The glasses with composition 64TeO2-15ZnO-(20-x)CdO-xBaO-1V2O5 (0⩽x⩽20 mol%) were prepared by conventional melt quenching technique. X-ray diffraction analysis was used to confirm the amorphous nature of the glasses. The optical absorption studies revealed that the cut-off wavelength (λα) decreases while optical band gap energy (Eopt) and Urbach energy (ΔE) values increase with an increase of BaO content. Refractive index (n) evaluated from Eopt was found to decrease with an increase of BaO content. The physical parameters such as density (ρ), molar volume (Vm), oxygen packing density (OPD), optical basicity (Λ), molar refraction (Rm), and metallization criterion (M) evaluated and discussed. FTIR and Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1/TeO3 and ZnO4 units as basic structural units. The glass transition temperature (Tg) of glass sample, onset crystallization temperature (To) and thermal stability ΔT were determined from Differential Scanning Calorimetry (DSC). Using electron paramagnetic resonance (EPR) spectra of vanadium glasses the spin Hamiltonian parameters and dipolar hyperfine coupling parameters of VO(2+) ions were calculated. It was found that V(4+) ions in these glasses exist as VO(2+) in octahedral coordination with a tetragonal distortion and have C4V symmetry with ground state dxy. Tetragonality (Δg∥/Δg⊥) of vanadium ion sites exhibited non-linear variation with BaO content. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Comparison of structured and unstructured physical activity training on predicted VO2max and heart rate variability in adolescents - a randomized control trial.

    Science.gov (United States)

    Sharma, Vivek Kumar; Subramanian, Senthil Kumar; Radhakrishnan, Krishnakumar; Rajendran, Rajathi; Ravindran, Balasubramanian Sulur; Arunachalam, Vinayathan

    2017-05-01

    Physical inactivity contributes to many health issues. The WHO-recommended physical activity for adolescents encompasses aerobic, resistance, and bone strengthening exercises aimed at achieving health-related physical fitness. Heart rate variability (HRV) and maximal aerobic capacity (VO2max) are considered as noninvasive measures of cardiovascular health. The objective of this study is to compare the effect of structured and unstructured physical training on maximal aerobic capacity and HRV among adolescents. We designed a single blinded, parallel, randomized active-controlled trial (Registration No. CTRI/2013/08/003897) to compare the physiological effects of 6 months of globally recommended structured physical activity (SPA), with that of unstructured physical activity (USPA) in healthy school-going adolescents. We recruited 439 healthy student volunteers (boys: 250, girls: 189) in the age group of 12-17 years. Randomization across the groups was done using age and gender stratified randomization method, and the participants were divided into two groups: SPA (n=219, boys: 117, girls: 102) and USPA (n=220, boys: 119, girls: 101). Depending on their training status and gender the participants in both SPA and USPA groups were further subdivided into the following four sub-groups: SPA athlete boys (n=22) and girls (n=17), SPA nonathlete boys (n=95) and girls (n=85), USPA athlete boys (n=23) and girls (n=17), and USPA nonathlete boys (n=96) and girls (n=84). We recorded HRV, body fat%, and VO2 max using Rockport Walk Fitness test before and after the intervention. Maximum aerobic capacity and heart rate variability increased significantly while heart rate, systolic blood pressure, diastolic blood pressure, and body fat percentage decreased significantly after both SPA and USPA intervention. However, the improvement was more in SPA as compared to USPA. SPA is more beneficial for improving cardiorespiratory fitness, HRV, and reducing body fat percentage in terms of

  9. Contraction-by-contraction VO2 and computer-controlled pump perfusion as novel techniques to study skeletal muscle metabolism in situ.

    Science.gov (United States)

    Hernández, Andrés; Goodwin, Matthew L; Lai, Nicola; Cabrera, Marco E; McDonald, James R; Gladden, L Bruce

    2010-03-01

    The purpose of this research was to develop new techniques to 1) rapidly sample venous O(2) saturation to determine contraction-by-contraction oxygen uptake (Vo(2)), and 2) precisely control the rate and pattern of blood flow adjustment from one chosen steady state to another. An indwelling inline oximeter probe connected to an Oximetrix 3 meter was used to sample venous oxygen concentration ([O(2)]) (via fractional saturation of Hb with O(2)). Data from the Oximetrix 3 were filtered, deconvolved, and processed by a moving average second by second. Computer software and a program written in-house were used to control blood flow with a peristaltic pump. The isolated canine gastrocnemius muscle complex (GS) in situ was utilized to test these techniques. A step change in metabolic rate was elicited by stimulating GS muscles via their sciatic nerves (supramaximal voltage, 8 V; 50 Hz, 0.2-ms pulse width; train duration 200 ms) at a rate of either 1 contraction/2 s, or 2 contractions/3 s. With arterial [O(2)] maintained constant, blood flow and calculated venous [O(2)] were averaged over each contraction cycle and used in the Fick equation to calculate contraction-by-contraction Vo(2). About 5-8 times more data points were obtained with this method compared with traditional manual sampling. Software-controlled pump perfusion enabled the ability to mimic spontaneous blood flow on-kinetics (tau: 14.3 s) as well as dramatically speed (tau: 2.0 s) and slow (tau: 63.3 s) on-kinetics. These new techniques significantly improve on existing methods for mechanistically altering blood flow kinetics as well as accurately measuring muscle oxygen consumption kinetics during transitions between metabolic rates.

  10. International Conference ML4CPS 2016

    CERN Document Server

    Niggemann, Oliver; Kühnert, Christian

    2017-01-01

    The work presents new approaches to Machine Learning for Cyber Physical Systems, experiences and visions. It contains some selected papers from the international Conference ML4CPS – Machine Learning for Cyber Physical Systems, which was held in Karlsruhe, September 29th, 2016. Cyber Physical Systems are characterized by their ability to adapt and to learn: They analyze their environment and, based on observations, they learn patterns, correlations and predictive models. Typical applications are condition monitoring, predictive maintenance, image processing and diagnosis. Machine Learning is the key technology for these developments. The Editors Prof. Dr.-Ing. Jürgen Beyerer is Professor at the Department for Interactive Real-Time Systems at the Karlsruhe Institute of Technology. In addition he manages the Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB. Prof. Dr. Oliver Niggemann is Professor for Embedded Software Engineering. His research interests are in the field of Di...

  11. The Ml Magnitude Scale In Italy

    Science.gov (United States)

    Gasperini, P.; Lolli, B.; Filippucci, M.; de Simoni, B.

    To improve the reliability of Ml magnitude estimates in Italy, we have updated the database of real Wood-Anderson (WA) and of simulated Wood Anderson (SWA) am- plitudes recently revised by Gasperini (2002). This was done by the re-reading of orig- inal WA seismograms, made available by the SISMOS Project of the Istituto Nazionale di Geofisica (INGV), as well as by the analysis of further Very Broad Band (VBB) recordings of the MEDNET network of INGV for the period from 1996 to 1998. The full operability, in the last five years, of a VBB station located exactly at the same site (TRI) of a former WA instrument allowed us to reliably infer a new attenuation function from the joined WA and SWA dataset. We found a significant deviation of the attenuation law from the standard Richter table at distances larger than 400 km where the latter overestimates the magnitude up to about 0.3 units. We also computed regionalized attenuation functions accounting for the differences in the propagation properties of seismic waves between the Adriatic (less attenuating) and Tyrrhenian (more attenuating) sides of the Italian peninsula. Using this improved Ml magnitude database we were also able to further improve the computation of duration (Md) and amplitude (Ma) magnitudes computed from short period vertical seismometers of the INGV as well as to analyze the time variation of the station calibrations. We found that the absolute amplification of INGV stations is underestimated almost exactly by a factor 2 starting from the entering upon in operation of the digital acquisition system at INGV in middle 1984.

  12. The effect of acute L-Carnitine supplementation on the blood lactate, glucose, VO2max and power in trained men: a brief report

    Directory of Open Access Journals (Sweden)

    Arazi H

    2013-04-01

    Full Text Available Background: Probably L-Carnitine can induce increasing of Pyruvate dehydrogenase activity, decreasing of lactic acid production and performance improvements due to the reinforcement of long chain fatty acid oxidation and stabilize of Coenzyme A (CoASH to free Coenzyme A (COA. Based on this, the aim of this study was to investigate the effect of acute L-Carnitine supplementation on blood lactate, glucose, VO2max and anaerobic power in trained men.Methods: Sixteen trained men (aged 19-23 volunteers from University of Guilan, facul-ty of Physical Education and Sport Sciences participated as subjects in this investiga-tion. Subjects divided to aerobic (A and anaerobic (An group randomly. In a double blind design, subjects participated in two separated tests by one week. Subjects ingested 3 grams of L-Carnitine supplementation or placebo (maltodextrin 90 minute before aerobic and anaerobic exercise. For aerobic activity used shuttle run 20 meter and for anaerobic activity used RAST test. Blood samples were collected 5 minute prior at rest and 4 minute post tests. Participants were asked in the morning to obtain fasting blood samples and perform tests. A t-test was used to detect differences between supplementa-tion and placebo groups in each exercise.Results: L-Carnitine group ((A 141.25±20.62 and (An 145.38±55.47 significantly had lower lactate concentration than placebo ((A 151.00±20.85 and (An 152.50±28.59 after tests (P≤0.05. L-Carnitine group ((A 136.00±19.74 and (An 115.50±13.64 had significa-ntly higher blood glucose compared to placebo ((A 121.62±15.65 and (An 110.12±12.63 too (P≤0.05. Also, VO2max, mean and maximum anaerobic power in L-Carnitine group were significantly more than ones in placebo (P<0.05.Conclusion: These findings indicate that acute oral supplementation of L-Carnitine can induce fatigue decreasing and improvement of aerobic and anaerobic performance.

  13. Polymorphism of NaVO2F2: a P2₁/c superstructure with pseudosymmetry of P2₁/m in the subcell.

    Science.gov (United States)

    Yu, Zi-Qun; Wang, Jing-Quan; Huang, Ya-Xi; Botis, Sanda M; Pan, Yuanming; Mi, Jin-Xiao

    2015-06-01

    The ADDSYM routine in the program PLATON [Spek (2015). Acta Cryst. C71, 9-18] has helped researchers to avoid structures of (metal-)organic compounds being reported in an unnecessarily low symmetry space group. However, determination of the correct space group may get more complicated in cases of pseudosymmetric inorganic compounds. One example is NaVO2F2, which was reported [Crosnier-Lopez et al. (1994). Eur. J. Solid State Inorg. Chem. 31, 957-965] in the acentric space group P2₁ based on properties but flagged by ADDSYM as (pseudo)centrosymmetric P2₁/m within default distance tolerances. Herein a systematic investigation reveals that NaVO2F2 exists in at least four polymorphs: P2₁, (I), P2₁/m, (II), P2₁/c, (III), and one or more low-temperature ones. The new centrosymmetric modification, (III), with the space group P2₁/c has a similar atomic packing geometry to phase (I), except for having a doubled c axis. The double-cell of phase (III) arises from atomic shifts from the glide plane c at (x, ¼, z). With increasing temperature, the number of observed reflections decreases. The odd l reflections gradually become weaker and, correspondingly, all atoms shift towards the glide plane, resulting in a gradual second-order transformation of (III) into high-temperature phase (II) (P2₁/m) at below 493 K. At least one first-order enantiotropic phase transition was observed below 139 K from both the single-crystal X-ray diffraction and the differential scanning calorimetry analyses. Periodic first-principles calculations within density functional theory show that both P2₁/c superstructure (III) and P2₁ substructure (I) are more stable than P2₁/m structure (II), and that P2₁/c superstructure (III) is more stable that P2₁ substructure (I).

  14. SED-ED, a workflow editor for computational biology experiments written in SED-ML.

    Science.gov (United States)

    Adams, Richard R

    2012-04-15

    The simulation experiment description markup language (SED-ML) is a new community data standard to encode computational biology experiments in a computer-readable XML format. Its widespread adoption will require the development of software support to work with SED-ML files. Here, we describe a software tool, SED-ED, to view, edit, validate and annotate SED-ML documents while shielding end-users from the underlying XML representation. SED-ED supports modellers who wish to create, understand and further develop a simulation description provided in SED-ML format. SED-ED is available as a standalone Java application, as an Eclipse plug-in and as an SBSI (www.sbsi.ed.ac.uk) plug-in, all under an MIT open-source license. Source code is at https://sed-ed-sedmleditor.googlecode.com/svn. The application itself is available from https://sourceforge.net/projects/jlibsedml/files/SED-ED/.

  15. Efek suplementasi kombinasi zat besi, vitamin C, dan asam folat terhadap peningkatan kadar hemoglobin dan kapasitas VO2 maks pada atlet sepak bola divisi utama dan satu nasional di Daerah Istimewa Yogyakarta

    Directory of Open Access Journals (Sweden)

    Zainal Abidin

    2006-11-01

    Full Text Available Background: Excessive endurance exercise of football players may break their blood cells and decrease the level of haemoglobin (Hb. These will influence the aerobic capacity (VO2 max and make the need for iron (Fe of an athlete more than that of common people. Objective: To know the influence of Fe, vitamin C (ascorbic acid, and  folic  acid  combined supplementation to the increase of VO2 max capacity  of  the  national  main  and  first division  club football players in Daerah Istimewa Yogyakarta. Method: The study was RCT (Randomized Controlled Trial experimental with a completely randomized design plan. The subjects were football players of Perserikatan Sepak Bola Indonesia Mataram (PSIM, Perserikatan Sepak Bola Sleman (PSS, and Perserikatan Sepak Bola Bantul (PERSIBA. They were then divided into two groups: treatment group and control group, each of them consisted of 35 players. Treatment group were given combined supplement capsules of 100 mg Fe, 100 mg vitamin C, and 2 mg folic acid three times a week for eight weeks, while the control group were given the placebo capsules. Before and after supplementation, their Hb and VO2  max were measured. However, the physical exercises were done based on the schedule, programmed by the clubs. Results: Combined supplementation of Fe, vitamin C, and folic acid could increase Hb level significantly (p=0.008, but there was no significant difference of VO2  max capacity between treatment group and control group (p=0.062. However, there was significant correlation between the increase of Hb level and VO  max capacity (r=0.712; p<0.001. Conclusion: Combined supplementation of Fe, vitamin C, and folic acid led to the increase of Hb level of main and first division clubs football players in Daerah Istimewa Yogyakarta, but could not influence their VO2 max capacity.

  16. Positive-bias gate-controlled metal-insulator transition in ultrathin VO2 channels with TiO2 gate dielectrics.

    Science.gov (United States)

    Yajima, Takeaki; Nishimura, Tomonori; Toriumi, Akira

    2015-12-14

    The next generation of electronics is likely to incorporate various functional materials, including those exhibiting ferroelectricity, ferromagnetism and metal-insulator transitions. Metal-insulator transitions can be controlled by electron doping, and so incorporating such a material in transistor channels will enable us to significantly modulate transistor current. However, such gate-controlled metal-insulator transitions have been challenging because of the limited number of electrons accumulated by gate dielectrics, or possible electrochemical reaction in ionic liquid gate. Here we achieve a positive-bias gate-controlled metal-insulator transition near the transition temperature. A significant number of electrons were accumulated via a high-permittivity TiO2 gate dielectric with subnanometre equivalent oxide thickness in the inverse-Schottky-gate geometry. An abrupt transition in the VO2 channel is further exploited, leading to a significant current modulation far beyond the capacitive coupling. This solid-state operation enables us to discuss the electrostatic mechanism as well as the collective nature of gate-controlled metal-insulator transitions, paving the pathway for developing functional field effect transistors.

  17. Pump-probe STM light emission spectroscopy for detection of photo-induced semiconductor-metal phase transition of VO2

    Science.gov (United States)

    Sakai, Joe; Katano, Satoshi; Kuwahara, Masashi; Uehara, Yoichi

    2017-10-01

    We attempted to observe pump-probe scanning tunneling microscopy (STM)-light emission (LE) from a VO2 thin film grown on a rutile TiO2(0 0 1) substrate, with an Ag tip fixed over a semiconducting domain. Laser pulses from a Ti:sapphire laser (wavelength 920 nm pulse width less than 1.5 ps) irradiated the tip-sample gap as pump and probe light sources. With a photon energy of 2.7 eV, suggesting phase transition from semiconducting monoclinic (M) to metallic rutile (R) phases in relation to the electronic band structure, faint LE was observed roughly 30 ps after the irradiation of the pump pulse, followed by retention for roughly 20 ps. The incident energy fluence of the pump pulse at the gap was five orders of magnitude lower than the threshold value for reported photo-induced M-R phase transition. The mechanism that makes it possible to reduce the threshold fluence is discussed.

  18. X-ray Spectroscopy of Ultra-thin Oxide/oxide Heteroepitaxial Films: A Case Study of Single-nanometer VO2/TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Quackenbush, Nicholas F. [Binghamton Univ., NY (United States); Paik, Hanjong [Cornell Univ., Ithaca, NY (United States); Woicik, Joseph C. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Arena, Dario A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Schlom, Darrell G. [Cornell Univ. and Kavli Inst. at Cornell for Nanoscale Science, Ithaca, NY (United States); Piper, Louis F. J. [Binghamton Univ., NY (United States)

    2015-08-21

    Epitaxial ultra-thin oxide films can support large percent level strains well beyond their bulk counterparts, thereby enabling strain-engineering in oxides that can tailor various phenomena. At these reduced dimensions (typically < 10 nm), contributions from the substrate can dwarf the signal from the epilayer, making it difficult to distinguish the properties of the epilayer from the bulk. This is especially true for oxide on oxide systems. Here, we have employed a combination of hard X-ray photoelectron spectroscopy (HAXPES) and angular soft X-ray absorption spectroscopy (XAS) to study epitaxial VO2/TiO2 (100) films ranging from 7.5 to 1 nm. We observe a low-temperature (300 K) insulating phase with evidence of vanadium-vanadium (V-V) dimers and a high-temperature (400 K) metallic phase absent of V-V dimers irrespective of film thickness. Results confirm that the metal insulator transition can exist at atomic dimensions and that biaxial strain can still be used to control the temperature of its transition when the interfaces are atomically sharp. Generally, our case study highlights the benefits of using non-destructive XAS and HAXPES to extract out information regarding the interfacial quality of the epilayers and spectroscopic signatures associated with exotic phenomena at these dimensions.

  19. Health-Related Physical Fitness in Healthy Untrained Men: Effects on VO2max, Jump Performance and Flexibility of Soccer and Moderate-Intensity Continuous Running

    Science.gov (United States)

    Milanović, Zoran; Pantelić, Saša; Sporiš, Goran; Mohr, Magni; Krustrup, Peter

    2015-01-01

    The purpose of this study was to determine the effects of recreational soccer (SOC) compared to moderate-intensity continuous running (RUN) on all health-related physical fitness components in healthy untrained men. Sixty-nine participants were recruited and randomly assigned to one of three groups, of which sixty-four completed the study: a soccer training group (SOC; n = 20, 34±4 (means±SD) years, 78.1±8.3 kg, 179±4 cm); a running group (RUN; n = 21, 32±4 years, 78.0±5.5 kg, 179±7 cm); or a passive control group (CON; n = 23, 30±3 years, 76.6±12.0 kg, 178±8 cm). The training intervention lasted 12 weeks and consisted of three 60-min sessions per week. All participants were tested for each of the following physical fitness components: maximal aerobic power, minute ventilation, maximal heart rate, squat jump (SJ), countermovement jump with arm swing (CMJ), sit-and-reach flexibility, and body composition. Over the 12 weeks, VO2max relative to body weight increased more (psoccer training and moderate-intensity running, partly due to large decreases in body mass. Additionally soccer training induced pronounced positive effects on jump performance and flexibility, making soccer an effective broad-spectrum fitness training intervention. PMID:26305880

  20. Isoflavones improve plasma homocysteine status and antioxidant defense system in healthy young men at rest but do not ameliorate oxidative stress induced by 80% VO2pk exercise.

    Science.gov (United States)

    Chen, Chung-Yen; Bakhiet, Raga M; Hart, Vanessa; Holtzman, Golde

    2005-01-01

    (1) Determination of whether isoflavones, as antioxidants and estrogen-like substances, reduce the atherosclerotic process. (2) Assessment of isoflavone anti-atherosclerotic effectiveness by means of measuring plasma markers of atherosclerosis: homocysteine (Hcy), antioxidant status, and lipid peroxidation. (3) Testing of isoflavone antioxidant effectiveness in the presence and absence of oxidative stress induced by exercise. Thirty subjects paired by aerobic fitness level were randomly assigned to either a placebo or high-genistein isoflavone extract (HGI, 150 mg/day) treatment. Blood samples were collected before and within 5 min, after 30 min at 80% peak oxygen consumption (VO(2)pk) exercise, and before and after 4-week supplementation. Plasma genistein and daidzein were significantly increased by 4-week HGI supplementation before and after exercise (p < 0.05). HGI decreased pre-exercise (pre-ex) plasma malondialdehyde (MDA) (p < 0.05) and Hcy (p = 0.01), and increased pre-ex blood total glutathione (TGSH) (p = 0.01), but did not diminish the increase of MDA and the decrease of TGSH due to the exercise. Furthermore, HGI supplementation enhanced pre-ex total antioxidant capacity (p < 0.05), but did not influence plasma vitamin C and E and uric acid concentrations. Isoflavones reduce plasma Hcy and have antioxidant activity in healthy young men. However, the effect of isoflavones on antioxidant systems may not be potent enough to diminish an abrupt surge of oxidative stress due to acute exercise. Copyright 2005 S. Karger AG, Basel.

  1. Comparison: Mediation Solutions of WSMOLX and WebML/WebRatio

    Science.gov (United States)

    Zaremba, Maciej; Zaharia, Raluca; Turati, Andrea; Brambilla, Marco; Vitvar, Tomas; Ceri, Stefano

    In this chapter we compare the WSMO/WSML/WSMX andWebML/WebRatio approaches to the SWS-Challenge workshop mediation scenario in terms of the utilized underlying technologies and delivered solutions. In the mediation scenario one partner uses Roset-taNet to define its B2B protocol while the other one operates on a proprietary solution. Both teams shown how these partners could be semantically integrated.

  2. Gonadotropin decrease induced by prolonged exercise at about 55% of the VO2max in different phases of the menstrual cycle.

    Science.gov (United States)

    Mastrogiacomo, I; Toderini, D; Bonanni, G; Bordin, D

    1990-06-01

    In order to evaluate the influence of physical exercise on the hypothalamic-pituitary-ovarian axis, we studied ten women in the early follicular phase (EFP), twelve in the late follicular phase (LEP) and nine in the luteal phase (LP). The test consisted of a 90-minute physical exercise on a motor driven treadmill at 55-60% of VO2max. Blood samples were taken before, during and after the test. Prolactin and cortisol did not increase in any phase. Estradiol showed a significant increase in LFP (from 361.5 +/- 110.6 to 472.7 +/- 138.9 pmol/L) and in LP (from 457.2 +/- 94.6 to 555.3 +/- 96.9 pmol/L) but not in EFP. Progesterone levels increased significantly only in LP (from 28.2 +/- 6.7 to 33.5 +/- 6.7 mmol/L): Luteinizing hormone (LH) levels decreased significantly in all phases: from 13.7 +/- 2.0 to 10.5 +/- 1.1 IU/L in EFP; from 14.6 +/- 2.1 to 11.5 +/- 1.9 IU/L in LFP and from 7.5 +/- 1.3 to 5.7 +/- 1.0 IU/L in LP, while follicle stimulating hormone (FSH) levels decreased only in LFP (from 8.1 +/- 0.5 to 6.7 +/- 0.6 IU/L). Our exercise protocol (prolonged, continuous and moderate) was able to cause a decrease in gonadotropins levels, and this phenomenon is not due to changes in the other tested hormones.

  3. ML 3.1 developer's guide.

    Energy Technology Data Exchange (ETDEWEB)

    Sala, Marzio; Hu, Jonathan Joseph (Sandia National Laboratories, Livermore, CA); Tuminaro, Raymond Stephen (Sandia National Laboratories, Livermore, CA)

    2004-05-01

    ML development was started in 1997 by Ray Tuminaro and Charles Tong. Currently, there are several full- and part-time developers. The kernel of ML is written in ANSI C, and there is a rich C++ interface for Trilinos users and developers. ML can be customized to run geometric and algebraic multigrid; it can solve a scalar or a vector equation (with constant number of equations per grid node), and it can solve a form of Maxwell's equations. For a general introduction to ML and its applications, we refer to the Users Guide [SHT04], and to the ML web site, http://software.sandia.gov/ml.

  4. Effect of regular exercise training on changes in HbA1c, BMI and VO2max among patients with type 2 diabetes mellitus: an 8-year trial.

    Science.gov (United States)

    Najafipour, Farzad; Mobasseri, Majid; Yavari, Abbas; Nadrian, Haidar; Aliasgarzadeh, Akbar; Mashinchi Abbasi, Naimeh; Niafar, Mitra; Houshyar Gharamaleki, Jalil; Sadra, Vahideh

    2017-01-01

    The effects of regular exercise on the health promotion of patients with type 2 diabetes mellitus (T2DM) have been well documented. The present study investigated the long-term effects of regular exercise training on biological indicators among these patients. In this quasi-experimental trial with pretest-post-test design, 65 patients with T2DM aged 33-69 years (experiment (35), control (30)) participated. After 8 years of conducting the program, the data on 30 patients (experiment (15), control (15)) were entered into analysis. The training program included aerobic exercise three sessions per week, 90 min, 50%-80% VO2max. Before and after the intervention, the biological indicators (hemoglobin A1c (HbA1c), body mass index (BMI) and VO2max) were measured. Data were analyzed using multivariate analysis of covariance. Our long-term exercise training program had a significant effect on HbA1C, BMI and Vo2max (PVO2max were significantly improved among the experiment group. Long-term regular physical activity training was found to be helpful in improving glycemic control, body composition and cardiovascular fitness among patients with T2DM. Long-term continuous physical activity offsets the deteriorations of biological indicators found in the control group. Further research, with a particular focus on practical and real-world programming, is needed to determine the responsive health outcomes of such long-term programs on the patients.

  5. Screening for spontaneous virulent mutants of erysiphe-graminis-f-sp-hordei on barley hordeum-vulgare lines with resistance genes ml-a-1 ml-a-6 ml-a-12 and ml-g

    DEFF Research Database (Denmark)

    Torp, J.; Jensen, Hans Peter

    1985-01-01

    Seedlings of 4 barley lines with powdery mildew resistance genes Ml-al, Ml-a6, Mla12 or Ml-g were inoculated with powdery mildew culture CR3 which is avirulent to the 4 host lines. Inoculation density was 1.2 infectious conidia/mm2, and in total 50 million conidia were screened for the occurrence...

  6. Health-Related Physical Fitness in Healthy Untrained Men: Effects on VO2max, Jump Performance and Flexibility of Soccer and Moderate-Intensity Continuous Running.

    Science.gov (United States)

    Milanović, Zoran; Pantelić, Saša; Sporiš, Goran; Mohr, Magni; Krustrup, Peter

    2015-01-01

    The purpose of this study was to determine the effects of recreational soccer (SOC) compared to moderate-intensity continuous running (RUN) on all health-related physical fitness components in healthy untrained men. Sixty-nine participants were recruited and randomly assigned to one of three groups, of which sixty-four completed the study: a soccer training group (SOC; n = 20, 34±4 (means±SD) years, 78.1±8.3 kg, 179±4 cm); a running group (RUN; n = 21, 32±4 years, 78.0±5.5 kg, 179±7 cm); or a passive control group (CON; n = 23, 30±3 years, 76.6±12.0 kg, 178±8 cm). The training intervention lasted 12 weeks and consisted of three 60-min sessions per week. All participants were tested for each of the following physical fitness components: maximal aerobic power, minute ventilation, maximal heart rate, squat jump (SJ), countermovement jump with arm swing (CMJ), sit-and-reach flexibility, and body composition. Over the 12 weeks, VO2max relative to body weight increased more (pRUN (21.5%, ES = 1.17) than in CON (-5.0%, ES = -0.24), partly due to large changes in body mass (-5.9, -5.7 and +2.6 kg, pRUN and CON, respectively). Over the 12 weeks, SJ and CMJ performance increased more (pRUN (3.3 and 3.0%, ES = 0.23 and 0.19) and CON (0.3 and 0.2%), while flexibility also increased more (pRUN and CON (0-2%). In conclusion, untrained men displayed marked improvements in maximal aerobic power after 12 weeks of soccer training and moderate-intensity running, partly due to large decreases in body mass. Additionally soccer training induced pronounced positive effects on jump performance and flexibility, making soccer an effective broad-spectrum fitness training intervention.

  7. Allelism of Genes in the Ml-a locus

    DEFF Research Database (Denmark)

    Giese, Nanna Henriette; Jensen, Hans Peter; Jørgensen, Jørgen Helms

    1980-01-01

    Seven barley lines or varieties, each with a different gene at the Ml-a locus for resistance to Erysiphe graminis were intercrossed. Progeny testing of the F2s using two different fungal isolates per cross provided evidence that there are two or more loci in the Ml-a region. Apparent recombinants...... were also screened for recombination between the Hor1 and Hor2 loci which are situated either side of the Ml-a locus. The cross between Ricardo and Iso42R (Rupee) yielded one possible recombinant, with Ml-a3 and Ml-a(Rul) in the coupling phase; other recombinants had wild-type genes in the coupling...... phase. Iso20R, derived from Hordeum spontaneum 'H204', carrying Ml-a6, had an additional gene, in close coupling with Ml-a6, tentatively named Ml-aSp2 or Reglv, causing an intermediate infection type with isolate EmA30. It is suggested that Ml-a(Ar) in Emir and Ml-a(Rul), shown to differ from other Ml-a...

  8. jmzML, an open-source Java API for mzML, the PSI standard for MS data.

    Science.gov (United States)

    Côté, Richard G; Reisinger, Florian; Martens, Lennart

    2010-04-01

    We here present jmzML, a Java API for the Proteomics Standards Initiative mzML data standard. Based on the Java Architecture for XML Binding and XPath-based XML indexer random-access XML parser, jmzML can handle arbitrarily large files in minimal memory, allowing easy and efficient processing of mzML files using the Java programming language. jmzML also automatically resolves internal XML references on-the-fly. The library (which includes a viewer) can be downloaded from http://jmzml.googlecode.com.

  9. NA-NET numerical analysis net

    Energy Technology Data Exchange (ETDEWEB)

    Dongarra, J. [Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science]|[Oak Ridge National Lab., TN (United States); Rosener, B. [Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science

    1991-12-01

    This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host ``na-net.ornl.gov`` at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where a member is currently located. As long as moving members change their e-mail address in the NA-NET everything works smoothly. The NA-NET system is currently located at Oak Ridge National Laboratory. It is running on the same machine that serves netlib. Netlib is a separate facility that distributes mathematical software via electronic mail. For more information on netlib consult, or send the one-line message ``send index`` to netlib{at}ornl.gov. The following report describes the current NA-NET system from both a user`s perspective and from an implementation perspective. Currently, there are over 2100 members in the NA-NET. An average of 110 mail messages pass through this facility daily.

  10. NA-NET numerical analysis net

    Energy Technology Data Exchange (ETDEWEB)

    Dongarra, J. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science Oak Ridge National Lab., TN (United States)); Rosener, B. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science)

    1991-12-01

    This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host na-net.ornl.gov'' at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where a member is currently located. As long as moving members change their e-mail address in the NA-NET everything works smoothly. The NA-NET system is currently located at Oak Ridge National Laboratory. It is running on the same machine that serves netlib. Netlib is a separate facility that distributes mathematical software via electronic mail. For more information on netlib consult, or send the one-line message send index'' to netlib{at}ornl.gov. The following report describes the current NA-NET system from both a user's perspective and from an implementation perspective. Currently, there are over 2100 members in the NA-NET. An average of 110 mail messages pass through this facility daily.

  11. Net Ecosystem Carbon Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Net Ecosystem Carbon Flux is defined as the year-over-year change in Total Ecosystem Carbon Stock, or the net rate of carbon exchange between an ecosystem and the...

  12. MathML in practice: issues and promise

    Directory of Open Access Journals (Sweden)

    T W Cole

    2006-11-01

    Full Text Available This paper discusses MathML, an XML-based standard for expressing mathematics - everything from elementary mathematics to undergraduate college-level mathematics. Limitations of pre-existing options led to the creation of MathML. MathML is designed to be useful for authoring and publishing, for creating online interactive math resources, and as a non-proprietary approach for archiving. MathML is supported by the W3C and by multiple scholarly publishers and vendors of computer-based mathematics software. The question now is whether MathML can achieve greater acceptance among authors and better integration with standards in related domains, either through cross-walks or through direct incorporation into other domain schemas.

  13. EFECTO DE UN PLAN DE ENTRENAMIENTO FÍSICO EN EL CONSUMO MÁXIMO DE OXÍGENO (VO2MÁX Y EL PESO EN PACIENTES HIPERTENSOS ADULTOS MAYORES ADSCRITOS A LA IPS CAJASAN (BUCARAMANGA

    Directory of Open Access Journals (Sweden)

    Jorge Luis Pérez Sierra

    2014-11-01

    Full Text Available El ejercicio físico adquiere cada vez más importancia en el tratamiento de los pacientes con hipertensión arterial, sobrepeso y obesidad. Desde hace más de cinco décadas se sabe que el ejercicio físico tiene efectos favorables en el tratamiento de la hipertensión arterial y otros factores de riesgo, es coadyuvante en el tratamiento de las enfermedades cardiovasculares y favorece el consumo máximo de oxígeno (VO2máx. El objetivo de este trabajo fue determinar el efecto de un plan de entrenamiento físico sobre el VO2máx y el peso en adultos mayores hipertensos adscritos a la IPS Cajasan Bucaramanga. Es una investigación cuasiexperimental, se tomaron cuarenta pacientes entre 60 y 75 años, en dos grupos iguales, uno con entrenamiento aeróbico, fuerza y flexibilidad (intervención, el otro, caminata diaria, (control, con duración de doce semanas. Se tomó pretest y postest con prueba de esfuerzo, peso, índice de masa corporal, perímetro de cintura. Se compararon los resultados. En el grupo intervención, el VO2máx aumentó 27%, el peso disminuyó 2,2 %, el perímetro de cintura bajó el 2%. En el grupo control no hubo cambios significativos.

  14. Efeito do tempo de intervalo da amostra ventilatória na variabilidade do consumo máximo de oxigênio (VO2 máx em jogadores de futebol profissional

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Santos Silva

    1999-04-01

    Full Text Available O propósito deste estudo foi verificar, em futebolistas profissionais, o impacto de sete intervalos de tempo sobre a variável fisiológica consumo máximo de oxigênio (VO2 máx. Dezoito jogadores de futebol com média de idade de 24 ± 4 anos (18-31, peso de 72,5 ± 5,9kg (62-83 e estatura de 176,5 ± 7,0cm (164-188 foram submetidos a teste ergométrico máximo em esteira rolante, utilizando-se protocolo escalonado contínuo. A resposta de freqüência cardíaca (FC foi registrada por meio de um eletrocardiógrafo computadorizado de 12 derivações simultâneas. A ventilação pulmonar (V E, o consumo de oxigênio (VO2, a produção de dióxido de carbono (VCO2 e a razão de troca respiratória (RER foram calculadas a partir de valores medidos por um sistema espirométrico computadorizado. Os resultados deste estudo demonstraram que houve variabilidade significante do VO2 máx (p < 0,05 somente quando se comparou a resposta instantânea respiração-a-respiração (breath-by-breath em relação aos outros intervalos de tempos analisados (10, 20, 30, 40, 50 e 60 segundos, respectivamente. Concluindo, durante o exercício de intensidade progressiva, observou-se que o aumento do VO2 foi proporcional à diminuição do intervalo de tempo da coleta ventilatória. O tempo de intervalo maior subestimou esse aumento. Assim, sugere-se que o avaliador utilize intervalos médios na faixa de tempo entre 10 e 60 segundos, pois não foi verificada diferença estatística significante entre esses intervalos.

  15. Ropivacaine 3.75 mg/ml, 5 mg/ml, or 7.5 mg/ml for cervical plexus block during carotid endarterectomy.

    Science.gov (United States)

    Umbrain, Vincent J; van Gorp, Viola L; Schmedding, Eric; Debing, Erik E; von Kemp, Karl; van den Brande, Pierre M; Camu, Frédéric

    2004-01-01

    To examine the effect of 225 mg (7.5 mg/mL), 150 mg (5 mg/mL), and 112.5 mg (3.75 mg/mL) ropivacaine on quality of cervical plexus block during carotid endarterectomy. Patients (n = 93) scheduled for carotid endarterectomy were randomized to receive a cervical plexus block with deep infiltration of 10 mL and superficial infiltration of 20-mL volumes of ropivacaine 7.5, 5.0, or 3.75 mg/mL. Pain, coughing, hemodynamic consequences of the block, postoperative visual analog scores, and pain satisfaction index were recorded. If necessary, anesthesia supplements with aliquots of 3 mL lidocaine 1% were given during surgery. Incidences of coughing and hoarseness were similar in all groups. More local anesthetic infiltrations were required in the ropivacaine 3.75-mg/mL and 5-mg/mL groups. Postoperatively, no intragroup differences were observed. A trend toward better pain satisfaction was observed in the ropivacaine 7.5-mg/mL group. The best quality of cervical plexus block associated with the smallest incidence of pain for patients undergoing carotid endarterectomy was obtained with 30 mL of 225 mg and 150 mg of ropivacaine, respectively.

  16. Professional Enterprise NET

    CERN Document Server

    Arking, Jon

    2010-01-01

    Comprehensive coverage to help experienced .NET developers create flexible, extensible enterprise application code If you're an experienced Microsoft .NET developer, you'll find in this book a road map to the latest enterprise development methodologies. It covers the tools you will use in addition to Visual Studio, including Spring.NET and nUnit, and applies to development with ASP.NET, C#, VB, Office (VBA), and database. You will find comprehensive coverage of the tools and practices that professional .NET developers need to master in order to build enterprise more flexible, testable, and ext

  17. Model-driven Service Engineering with SoaML

    Science.gov (United States)

    Elvesæter, Brian; Carrez, Cyril; Mohagheghi, Parastoo; Berre, Arne-Jørgen; Johnsen, Svein G.; Solberg, Arnor

    This chapter presents a model-driven service engineering (MDSE) methodology that uses OMG MDA specifications such as BMM, BPMN and SoaML to identify and specify services within a service-oriented architecture. The methodology takes advantage of business modelling practices and provides a guide to service modelling with SoaML. The presentation is case-driven and illuminated using the telecommunication example. The chapter focuses in particular on the use of the SoaML modelling language as a means for expressing service specifications that are aligned with business models and can be realized in different platform technologies.

  18. ML at ATLAS&CMS : setting the stage

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    In the early days of the LHC the canonical problems of classification and regression were mostly addressed using simple cut-based techniques. Today, ML techniques (some already pioneered in pre-LHC or non collider experiments) play a fundamental role in the toolbox of any experimentalist. The talk will introduce, through a representative collection of examples, the problems addressed with ML techniques at the LHC. The goal of the talk is to set the stage for a constructive discussion with non-HEP ML practitioners, focusing on the specificities of HEP applications.

  19. Automation of Safety Analysis with SysML Models Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project was a small proof-of-concept case study, generating SysML model information as a side effect of safety analysis. A prototype FMEA Assistant was...

  20. Preparing for the future: opportunities for ML in ATLAS & CMS

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    ML is an established tool in HEP and there are many examples which demonstrate its importance for the kind of classification and regression problem we have in our field. However, there is also a big potential for future applications in yet untapped areas. I will summarise these opportunities and highlight recent, ongoing and planned studies of novel ML applications in HEP. Certain aspects of the problems we are faced with in HEP are quite unique and represent interesting benchmark problems for the ML community as a whole. Hence, efficient communication and close interaction between the ML and HEP community is expected to lead to promising cross-fertilisation. This talk attempts to serve as a starting point for such a prospective collaboration.

  1. WeedML: a Tool for Collaborative Weed Demographic Modeling

    OpenAIRE

    Holst, Niels

    2010-01-01

    WeedML is a proposed standard to formulate models of weed demography, or maybe even complex models in general, that are both transparent and straightforward to re-use as building blocks for new models. The paper describes the design and thoughts behind WeedML which relies on XML and object-oriented systems development. Proof-of-concept software is provided as open-source C++ code and executables that can be downloaded freely.

  2. From WaterML to TimeseriesML: Evolution and implications for cross-domain data interoperability

    Science.gov (United States)

    Arctur, D. K.; Taylor, P.; Lowe, D.; Tomkins, J.; Teng, W. L.; Ames, D. P.

    2015-12-01

    WaterML 2.0 part 1 was adopted by the Open Geospatial Consortium (OGC) in 2012 as an international standard profile of the Observations and Measurements conceptual model, for exchange of water observations time series data. It is implemented by national data producers such as the US Geological Survey for surface water time series, the NOAA/National Weather Service for forecast time series, the French Geological Survey for groundwater level monitoring, and the Australian Bureau of Meteorology for surface water observations. But WaterML 2.0 is not "just for water". The World Meteorological Organization (WMO) has recognized its potential role as a common time series description that could work for multiple application domains such as meteorology, climate, oceanography, and others. Accordingly, the WMO requested the OGC to migrate the non-hydrology parts of WaterML 2.0 to a new standard to be called TimeseriesML. This would then be considered by WMO for adoption as an operational standard globally. What does this mean for the geosciences? How far can this time series description be applied? What about time series of satellite retrievals? What will happen to WaterML 2.0 (and applications that work with it) when TimeseriesML is finished? These are among the questions we address in this presentation.

  3. WaveNet

    Science.gov (United States)

    2015-10-30

    Coastal Inlets Research Program WaveNet WaveNet is a web-based, Graphical-User-Interface ( GUI ) data management tool developed for Corps coastal...generates tabular and graphical information for project planning and design documents. The WaveNet is a web-based GUI designed to provide users with a...data from different sources, and employs a combination of Fortran, Python and Matlab codes to process and analyze data for USACE applications

  4. HepML, an XML-based format for describing simulated data in high energy physics

    Science.gov (United States)

    Belov, S.; Dudko, L.; Kekelidze, D.; Sherstnev, A.

    2010-10-01

    In this paper we describe a HepML format and a corresponding C++ library developed for keeping complete description of parton level events in a unified and flexible form. HepML tags contain enough information to understand what kind of physics the simulated events describe and how the events have been prepared. A HepML block can be included into event files in the LHEF format. The structure of the HepML block is described by means of several XML Schemas. The Schemas define necessary information for the HepML block and how this information should be located within the block. The library libhepml is a C++ library intended for parsing and serialization of HepML tags, and representing the HepML block in computer memory. The library is an API for external software. For example, Matrix Element Monte Carlo event generators can use the library for preparing and writing a header of an LHEF file in the form of HepML tags. In turn, Showering and Hadronization event generators can parse the HepML header and get the information in the form of C++ classes. libhepml can be used in C++, C, and Fortran programs. All necessary parts of HepML have been prepared and we present the project to the HEP community. Program summaryProgram title: libhepml Catalogue identifier: AEGL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPLv3 No. of lines in distributed program, including test data, etc.: 138 866 No. of bytes in distributed program, including test data, etc.: 613 122 Distribution format: tar.gz Programming language: C++, C Computer: PCs and workstations Operating system: Scientific Linux CERN 4/5, Ubuntu 9.10 RAM: 1 073 741 824 bytes (1 Gb) Classification: 6.2, 11.1, 11.2 External routines: Xerces XML library ( http://xerces.apache.org/xerces-c/), Expat XML Parser ( http://expat.sourceforge.net/) Nature of problem: Monte Carlo simulation in high

  5. QuakeML 2.0: Recent developments

    Science.gov (United States)

    Euchner, Fabian; Kästli, Philipp; Heiniger, Lukas; Saul, Joachim; Schorlemmer, Danijel; Clinton, John

    2016-04-01

    QuakeML is a community-backed data model for seismic event parameter description. Its current version 1.2, released in 2013, has become the gold standard for parametric data dissemination at seismological data centers, and has been adopted as an FDSN standard. It is supported by several popular software products and data services, such as FDSN event web services, QuakePy, and SeisComP3. Work on the successor version 2.0 is under way since 2015. The scope of QuakeML has been expanded beyond event parameter description. Thanks to a modular architecture, many thematic packages have been added, which cover peak ground motion, site and station characterization, hydraulic parameters of borehole injection processes, and macroseismics. The first three packages can be considered near final and implementations of program codes and SQL databases are in productive use at various institutions. A public community review process has been initiated in order to turn them into community-approved standards. The most recent addition is a package for single station quake location, which allows a detailed probabilistic description of event parameters recorded at a single station. This package adds some information elements such as angle of incidence, frequency-dependent phase picks, and dispersion relations. The package containing common data types has been extended with a generic type for probability density functions. While on Earth, single station methods are niche applications, they are of prominent interest in planetary seismology, e.g., the NASA InSight mission to Mars. So far, QuakeML is lacking a description of seismic instrumentation (inventory). There are two existing standards of younger age (FDSN StationXML and SeisComP3 Inventory XML). We discuss their respective strengths, differences, and how they could be combined into an inventory package for QuakeML, thus allowing full interoperability with other QuakeML data types. QuakeML is accompanied by QuakePy, a Python package

  6. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt

    1991-01-01

    This paper describes how Coloured Petri Nets (CP-nets) have been developed — from being a promising theoretical model to being a full-fledged language for the design, specification, simulation, validation and implementation of large software systems (and other systems in which human beings and...... use of CP-nets — because it means that the function representation and the translations (which are a bit mathematically complex) no longer are parts of the basic definition of CP-nets. Instead they are parts of the invariant method (which anyway demands considerable mathematical skills...

  7. Game Coloured Petri Nets

    DEFF Research Database (Denmark)

    Westergaard, Michael

    2006-01-01

    This paper introduces the notion of game coloured Petri nets. This allows the modeler to explicitly model what parts of the model comprise the modeled system and what parts are the environment of the modeled system. We give the formal definition of game coloured Petri nets, a means of reachability...... analysis of this net class, and an application of game coloured Petri nets to automatically generate easy-to-understand visualizations of the model by exploiting the knowledge that some parts of the model are not interesting from a visualization perspective (i.e. they are part of the environment...

  8. Programming NET Web Services

    CERN Document Server

    Ferrara, Alex

    2007-01-01

    Web services are poised to become a key technology for a wide range of Internet-enabled applications, spanning everything from straight B2B systems to mobile devices and proprietary in-house software. While there are several tools and platforms that can be used for building web services, developers are finding a powerful tool in Microsoft's .NET Framework and Visual Studio .NET. Designed from scratch to support the development of web services, the .NET Framework simplifies the process--programmers find that tasks that took an hour using the SOAP Toolkit take just minutes. Programming .NET

  9. Annotating Coloured Petri Nets

    DEFF Research Database (Denmark)

    Lindstrøm, Bo; Wells, Lisa Marie

    2002-01-01

    -net. An example of such auxiliary information is a counter which is associated with a token to be able to do performance analysis. Modifying colour sets and arc inscriptions in a CP-net to support a specific use may lead to creation of several slightly different CP-nets – only to support the different uses...... a method which makes it possible to associate auxiliary information, called annotations, with tokens without modifying the colour sets of the CP-net. Annotations are pieces of information that are not essential for determining the behaviour of the system being modelled, but are rather added to support...

  10. Análise de lesão muscular e comportamento do vo2máx entre um programa de treinamento de corrida em piscina funda e corrida em terra

    Directory of Open Access Journals (Sweden)

    Alecsandra Pinheiro Vendrusculo

    2014-12-01

    Full Text Available Objetivo: avaliar e comparar a ocorrência de lesão muscular e o comportamento do consumo máximo de oxigênio (VO2máx entre um programa de treinamento de corrida em terra (CT e um programa de treinamento de corrida em piscina funda (CPF. Método: participaram do estudo 14 indivíduos não treinados. O treinamento durou 12 semanas, três vezes na semana. Analisou-se o comportamento do VO2máx pré e pós-treinamento. Para a análise de lesão muscular utilizou-se a enzima creatina quinase (CK pré, logo após, pós 24h e 48h da sessão, a cada quatro semanas e a ultrassonografia (US a cada quatro semanas. Resultados: Quando se analisou o comportamento do VO2máx, verificou-se diferença entre os valores pré e pós-treinamento, mas não houve diferença entre os grupos. Quanto à CK, verificou-se diferença entre os grupos na medida 24hs após, o que não foi verificado nas outras medidas. Para o grupo CT, somente nas coletas dois e quatro verificou-se diferença entre as medidas 24hs após e 48hs após, mas não ocorreram diferenças significativas entre as medidas e nem entre os grupos. Na US, nenhum dos grupos apresentou diferença significativa entre os exames, mas no grupo CT apareceram duas lesões na terceira coleta. Considerações finais: concluiu-se que as duas modalidades de treinamento proporcionam uma melhora na aptidão cardiorrespiratória e, embora não tenha ocorrido diferença significativa em algumas coletas de CK entre os grupos, a CT provocou maiores aumentos na concentração sanguínea de CK, sugerindo que o meio líquido pode ser o mais indicado para proteger o sistema musculoesquelético.

  11. Net zero water

    CSIR Research Space (South Africa)

    Lindeque, M

    2013-01-01

    Full Text Available Is it possible to develop a building that uses a net zero amount of water? In recent years it has become evident that it is possible to have buildings that use a net zero amount of electricity. This is possible when the building is taken off...

  12. SolNet

    DEFF Research Database (Denmark)

    Jordan, Ulrike; Vajen, Klaus; Bales, Chris

    2014-01-01

    SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference...

  13. Kunstige neurale net

    DEFF Research Database (Denmark)

    Hørning, Annette

    1994-01-01

    Artiklen beskæftiger sig med muligheden for at anvende kunstige neurale net i forbindelse med datamatisk procession af naturligt sprog, specielt automatisk talegenkendelse.......Artiklen beskæftiger sig med muligheden for at anvende kunstige neurale net i forbindelse med datamatisk procession af naturligt sprog, specielt automatisk talegenkendelse....

  14. DocML: A Digital Library of University Data.

    Science.gov (United States)

    Papadakis, Ioannis; Karakoidas, Vassileios; Chrissikopoulos, Vassileios

    2002-01-01

    Describes DocML, a Web-based digital library of university data that is used to build a system capable of preserving and managing student assignments. Topics include requirements for a digital library of university data; metadata and XML; three-tier architecture; user interface; searching; browsing; content delivery; and administrative issues.…

  15. Large-scale variations of M/L

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Y.; Shaham, J.; Shaviv, G.

    1982-11-15

    The large-scale behavior of M/L is suggested to be related to segregation between dark and luminous matter (galaxies). It is suggested that during the collapse and virialization of groups and clusters the galactic halos are tidally disrupted and a smooth background of dark matter is formed; galaxies moving through this background lose energy due to dynamical friction, which is the main process considered here. We assume that at the epoch of galaxy formation (M/L) had some universal, scale independent, value, (M/L)/sub infinity/. As systems of galaxies evolved, the energy in their luminous component was dissipated. That component became denser and consequently the observed M/L decreased. (M/L)/(M/L)/sub infinity/ depends on the (age of the universe/dissipation time scale) ratio, which is found to be smaller than 1 for all relevant parameters. The main predictions of the present model are: (i) M/L is a nondecreasing function of R, and it reaches its limiting value, (M/L)/sub infinity/, on the scale of superclusters; (ii) 0.4< or =..cap omega../sub 0/< or =0.5 and -1.5< or =n< or =-1.0, where n is the index of the power spectrum of the primordial isothermal density perturbations. Because of ambiguities in data and simplification in the model, prediction (ii) may be less accruate than prediction (i).

  16. CytometryML: a markup language for analytical cytology

    Science.gov (United States)

    Leif, Robert C.; Leif, Stephanie H.; Leif, Suzanne B.

    2003-06-01

    Cytometry Markup Language, CytometryML, is a proposed new analytical cytology data standard. CytometryML is a set of XML schemas for encoding both flow cytometry and digital microscopy text based data types. CytometryML schemas reference both DICOM (Digital Imaging and Communications in Medicine) codes and FCS keywords. These schemas provide representations for the keywords in FCS 3.0 and will soon include DICOM microscopic image data. Flow Cytometry Standard (FCS) list-mode has been mapped to the DICOM Waveform Information Object. A preliminary version of a list mode binary data type, which does not presently exist in DICOM, has been designed. This binary type is required to enhance the storage and transmission of flow cytometry and digital microscopy data. Index files based on Waveform indices will be used to rapidly locate the cells present in individual subsets. DICOM has the advantage of employing standard file types, TIF and JPEG, for Digital Microscopy. Using an XML schema based representation means that standard commercial software packages such as Excel and MathCad can be used to analyze, display, and store analytical cytometry data. Furthermore, by providing one standard for both DICOM data and analytical cytology data, it eliminates the need to create and maintain special purpose interfaces for analytical cytology data thereby integrating the data into the larger DICOM and other clinical communities. A draft version of CytometryML is available at www.newportinstruments.com.

  17. Adductor Canal Block With 10 mL Versus 30 mL Local Anesthetics and Quadriceps Strength

    DEFF Research Database (Denmark)

    Jæger, Pia; Koscielniak-Nielsen, Zbigniew J; Hilsted, Karen Lisa

    2015-01-01

    BACKGROUND AND OBJECTIVES: Adductor canal block (ACB) is predominantly a sensory nerve block, but excess volume may spread to the femoral triangle and reduce quadriceps strength. We hypothesized that reducing the local anesthetic volume from 30 to 10 mL may lead to fewer subjects with quadriceps...... weakness. METHODS: We performed a paired, blinded, randomized trial including healthy men. All subjects received bilateral ACBs with ropivacaine 0.1%; 10 mL in 1 leg and 30 mL in the other leg. The primary outcome was the difference in number of subjects with quadriceps strength reduced by more than 25......% from baseline in 2 consecutive assessments. Secondary outcomes were quadriceps strength as a percentage of baseline at predefined time points, functional outcome assessed by the 30-Second Chair Stand Test (1 leg at a time), and sensory block. Clinicaltrials.gov Identifier: NCT01981746. RESULTS: We...

  18. Comparação entre os métodos direto e indireto de determinação do VO 2máx de praticantes de corrida

    Directory of Open Access Journals (Sweden)

    Ana Claudia Pelissari Kravchychyn

    2015-02-01

    Full Text Available INTRODUÇÃO: testes diretos são considerados "padrão ouro" para determinar variáveis fisiológicas, porém o seu custo financeiro é elevado e há a necessidade de mão de obra especializada para sua operacionalização. Sendo assim, os testes indiretos são utilizados pela maioria dos profissionais de Educação Física como uma alternativa acessível à falta da medida direta. OBJETIVO: comparar os valores de consumo máximo de oxigênio (VO2máx determinados diretamente por um sistema de espirometria com valores determinados a partir de protocolos indiretos. MÉTODOS: participaram 15 pessoas do gênero masculino (27,4 ± 3,5 anos, fisicamente ativas, que realizaram o teste incremental em esteira rolante para determinação direta do VO2máx com analisador de gases. Os testes para predição do VO2máx foram: ErgoPC; Polar Fitness Test; testes do banco e de Cooper. Foi utilizada a estatística descritiva (média ± desvio padrão - DP; a esfericidade foi testada pelo teste de Mauchly, os métodos foram comparados por ANOVA de medidas repetidas com o ajuste de Bonferroni para comparações múltiplas. A normalidade dos dados foi aferida pelo teste de Shapiro-Wilk e também foi aplicado o teste coeficiente de correlação de Pearson, adotando-se p<0,05. RESULTADOS: o valor médio de VO2máx direto foi de 55,8 ± 6,1 ml•kg-1•min-1 e os valores para os testes indiretos, percentual de subestimação e coeficiente de correlação, foram, respectivamente: ErgoPc 33,7 ± 4,5 ml•kg-1•min-1 (39,6%; r = 0,71; p<0,001; Polar Fitness Test 53,2 ± 6,4 ml•kg-1•min-1 (4,6%; r = 0,64; p = 0,774; teste do banco 48,8 ± 6,3 ml•kg-1•min-1 (12,5%; r = 0,60; P=0,001 e de Cooper 43,9 ± 7,9 ml•kg-1•min-1 (21,4%; r = 0,65; p<0,001. CONCLUSÃO: os métodos indiretos podem sugerir sobrecarga de treino inferior ou superior para adaptações fisiológicas pretendidas por subestimarem o direto, sendo o Polar Fitness Test o mais indicado para uso di

  19. Efecto de un programa de entrenamiento para mejorar el consumo máximo de oxígeno (VO2max.) de futbolistas de un equipo de primera división del fútbol de Costa Rica

    OpenAIRE

    Milton Rivas, Oscar

    2015-01-01

    Propósito: determinar el efecto de un programa de entrenamiento para mejorar el consumo máximo de oxígeno, en futbolistas de un equipo primera división del fútbol de Costa Rica. Sujetos: 24 sujetos masculinos, con una edad promedio de 25,7 ± 3,4 años. Instrumentos: Se utilizó el Yo-Yo test en su versión de recuperación intermitente (IR2), para valorar los posibles cambios en el consumo máximo de oxígeno (VO2max.) de los futbolistas. Procedimiento: para la pretemporada para el torneo de invier...

  20. Pro NET Best Practices

    CERN Document Server

    Ritchie, Stephen D

    2011-01-01

    Pro .NET Best Practices is a practical reference to the best practices that you can apply to your .NET projects today. You will learn standards, techniques, and conventions that are sharply focused, realistic and helpful for achieving results, steering clear of unproven, idealistic, and impractical recommendations. Pro .NET Best Practices covers a broad range of practices and principles that development experts agree are the right ways to develop software, which includes continuous integration, automated testing, automated deployment, and code analysis. Whether the solution is from a free and

  1. Getting to Net Zero

    Energy Technology Data Exchange (ETDEWEB)

    2016-09-01

    The technology necessary to build net zero energy buildings (NZEBs) is ready and available today, however, building to net zero energy performance levels can be challenging. Energy efficiency measures, onsite energy generation resources, load matching and grid interaction, climatic factors, and local policies vary from location to location and require unique methods of constructing NZEBs. It is recommended that Components start looking into how to construct and operate NZEBs now as there is a learning curve to net zero construction and FY 2020 is just around the corner.

  2. Instant Lucene.NET

    CERN Document Server

    Heydt, Michael

    2013-01-01

    Filled with practical, step-by-step instructions and clear explanations for the most important and useful tasks. A step-by-step guide that helps you to index, search, and retrieve unstructured data with the help of Lucene.NET.Instant Lucene.NET How-to is essential for developers new to Lucene and Lucene.NET who are looking to get an immediate foundational understanding of how to use the library in their application. It's assumed you have programming experience in C# already, but not that you have experience with search techniques such as information retrieval theory (although there will be a l

  3. The Effects of Different Training Backgrounds on VO2 Responses to All-Out and Supramaximal Constant-Velocity Running Bouts.

    Science.gov (United States)

    de Aguiar, Rafael Alves; Lisbôa, Felipe Domingos; Turnes, Tiago; Cruz, Rogério Santos de Oliveira; Caputo, Fabrizio

    2015-01-01

    To investigate the impact of different training backgrounds on pulmonary oxygen uptake (V̇O2) responses during all-out and supramaximal constant-velocity running exercises, nine sprinters (SPRs) and eight endurance runners (ENDs) performed an incremental test for maximal aerobic velocity (MAV) assessment and two supramaximal running exercises (1-min all-out test and constant-velocity exercise). The V̇O2 responses were continuously determined during the tests (K4b2, Cosmed, Italy). A mono-exponential function was used to describe the V̇O2 onset kinetics during constant-velocity test at 110%MAV, while during 1-min all-out test the peak of V̇O2 (V̇O2peak), the time to achieve the V̇O2peak (tV̇O2peak) and the V̇O2 decrease at last of the test was determined to characterize the V̇O2 response. During constant-velocity exercise, ENDs had a faster V̇O2 kinetics than SPRs (12.7 ± 3.0 vs. 19.3 ± 5.6 s; p < 0.001). During the 1-min all-out test, ENDs presented slower tV̇O2peak than SPRs (40.6 ± 6.8 and 28.8 ± 6.4 s, respectively; p = 0.002) and had a similar V̇O2peak relative to the V̇O2max (88 ± 8 and 83 ± 6%, respectively; p = 0.157). Finally, SPRs was the only group that presented a V̇O2 decrease in the last half of the test (-1.8 ± 2.3 and 3.5 ± 2.3 ml.kg-1.min-1, respectively; p < 0.001). In summary, SPRs have a faster V̇O2 response when maximum intensity is required and a high maximum intensity during all-out running exercise seems to lead to a higher decrease in V̇O2 in the last part of the exercise.

  4. The Effects of Different Training Backgrounds on VO2 Responses to All-Out and Supramaximal Constant-Velocity Running Bouts.

    Directory of Open Access Journals (Sweden)

    Rafael Alves de Aguiar

    Full Text Available To investigate the impact of different training backgrounds on pulmonary oxygen uptake (V̇O2 responses during all-out and supramaximal constant-velocity running exercises, nine sprinters (SPRs and eight endurance runners (ENDs performed an incremental test for maximal aerobic velocity (MAV assessment and two supramaximal running exercises (1-min all-out test and constant-velocity exercise. The V̇O2 responses were continuously determined during the tests (K4b2, Cosmed, Italy. A mono-exponential function was used to describe the V̇O2 onset kinetics during constant-velocity test at 110%MAV, while during 1-min all-out test the peak of V̇O2 (V̇O2peak, the time to achieve the V̇O2peak (tV̇O2peak and the V̇O2 decrease at last of the test was determined to characterize the V̇O2 response. During constant-velocity exercise, ENDs had a faster V̇O2 kinetics than SPRs (12.7 ± 3.0 vs. 19.3 ± 5.6 s; p < 0.001. During the 1-min all-out test, ENDs presented slower tV̇O2peak than SPRs (40.6 ± 6.8 and 28.8 ± 6.4 s, respectively; p = 0.002 and had a similar V̇O2peak relative to the V̇O2max (88 ± 8 and 83 ± 6%, respectively; p = 0.157. Finally, SPRs was the only group that presented a V̇O2 decrease in the last half of the test (-1.8 ± 2.3 and 3.5 ± 2.3 ml.kg-1.min-1, respectively; p < 0.001. In summary, SPRs have a faster V̇O2 response when maximum intensity is required and a high maximum intensity during all-out running exercise seems to lead to a higher decrease in V̇O2 in the last part of the exercise.

  5. IBM techexplorer and MathML: Interactive Multimodal Scientific Documents

    Science.gov (United States)

    Diaz, Angel

    2001-06-01

    The World Wide Web provides a standard publishing platform for disseminating scientific and technical articles, books, journals, courseware, or even homework on the internet; however, the transition from paper to web-based interactive content has brought new opportunities for creating interactive content. Students, scientists, and engineers are now faced with the task of rendering the 2D presentational structure of mathematics, harnessing the wealth of scientific and technical software, and creating truly accessible scientific portals across international boundaries and markets. The recent emergence of World Wide Web Consortium (W3C) standards such as the Mathematical Markup Language (MathML), Language (XSL), and Aural CSS (ACSS) provide a foundation whereby mathematics can be displayed, enlivened, computed, and audio formatted. With interoperability ensured by standards, software applications can be easily brought together to create extensible and interactive scientific content. In this presentation we will provide an overview of the IBM techexplorer Hypermedia Browser, a web browser plug-in and ActiveX control aimed at bringing interactive mathematics to the masses across platforms and applications. We will demonstrate "live" mathematics where documents that contain MathML expressions can be edited and computed right inside your favorite web browser. This demonstration will be generalized as we show how MathML can be used to enliven even PowerPoint presentations. Finally, we will close the loop by demonstrating a novel approach to spoken mathematics based on MathML, DOM, XSL, ACSS, techexplorer, and IBM ViaVoice. By making use of techexplorer as the glue that binds the rendered content to the web browser, the back-end computation software, the Java applets that augment the exposition, and voice-rendering systems such as ViaVoice, authors can indeed create truly extensible and interactive scientific content. For more information see: [http

  6. Maintenance of sterility in 1-mL polypropylene syringes.

    Science.gov (United States)

    Gonzalez, Serafin; Miller, Darlene; Murphy, Steven P

    2007-09-15

    The sterility of syringes filled with a growth-promoting broth when stored under various temperature conditions was studied. Samples of tryptic soy broth (TSB) were injected into 150 1-mL polypropylene syringes and incubated at 33-37 degrees C for 14 days, after which time they were visually inspected for microbial contamination. In addition to visual inspection, the sterility of all syringes was tested by inoculating samples into 10-mL tubes of thioglycollate broth, incubating at 35 degrees C, and observing for growth for 5 days. After the 14-day incubation period, 30 syringes were removed for sterility validation and microbial growth promotion. TSB from 15 syringes was transferred into sterile culture tubes and challenged with Staphylococcus aureus, Escherichia coli, Bacillus cereus, Candida albicans, and Aspergillus niger. The remaining 120 syringes were repackaged and stored at room temperature (22 degrees C), in a refrigerator (5 degrees C), or in a freezer (-20 degrees C). The sterility of the samples was evaluated at 30 days, 45 days, three months, and six months. No microbial growth was detected by visual inspection in any of the 15 syringes examined for turbidity during validation testing. All study syringes (n = 120) remained sterile throughout the respective evaluation periods, regardless of storage condition. Growth-promoting broth stored in 1-mL polypropylene syringes remained sterile when stored at room temperature, in a refrigerator, or in a freezer for six months.

  7. Mass spectrometer output file format mzML.

    Science.gov (United States)

    Deutsch, Eric W

    2010-01-01

    Mass spectrometry is an important technique for analyzing proteins and other biomolecular compounds in biological samples. Each of the vendors of these mass spectrometers uses a different proprietary binary output file format, which has hindered data sharing and the development of open source software for downstream analysis. The solution has been to develop, with the full participation of academic researchers as well as software and hardware vendors, an open XML-based format for encoding mass spectrometer output files, and then to write software to use this format for archiving, sharing, and processing. This chapter presents the various components and information available for this format, mzML. In addition to the XML schema that defines the file structure, a controlled vocabulary provides clear terms and definitions for the spectral metadata, and a semantic validation rules mapping file allows the mzML semantic validator to insure that an mzML document complies with one of several levels of requirements. Complete documentation and example files insure that the format may be uniformly implemented. At the time of release, there already existed several implementations of the format and vendors have committed to supporting the format in their products.

  8. Net Zero Energy Buildings

    DEFF Research Database (Denmark)

    Marszal, Anna Joanna; Bourrelle, Julien S.; Musall, Eike

    2010-01-01

    and identify possible renewable energy supply options which may be considered in calculations. Finally, the gap between the methodology proposed by each organisation and their respective national building code is assessed; providing an overview of the possible changes building codes will need to undergo......The international cooperation project IEA SHC Task 40 / ECBCS Annex 52 “Towards Net Zero Energy Solar Buildings”, attempts to develop a common understanding and to set up the basis for an international definition framework of Net Zero Energy Buildings (Net ZEBs). The understanding of such buildings...... parameters used in the calculations are discussed and the various renewable supply options considered in the methodologies are summarised graphically. Thus, the paper helps to understand different existing approaches to calculate energy balance in Net ZEBs, highlights the importance of variables selection...

  9. PhysioNet

    Data.gov (United States)

    U.S. Department of Health & Human Services — The PhysioNet Resource is intended to stimulate current research and new investigations in the study of complex biomedical and physiologic signals. It offers free...

  10. NetSig

    DEFF Research Database (Denmark)

    Horn, Heiko; Lawrence, Michael S; Chouinard, Candace R

    2018-01-01

    Methods that integrate molecular network information and tumor genome data could complement gene-based statistical tests to identify likely new cancer genes; but such approaches are challenging to validate at scale, and their predictive value remains unclear. We developed a robust statistic (Net......Sig) that integrates protein interaction networks with data from 4,742 tumor exomes. NetSig can accurately classify known driver genes in 60% of tested tumor types and predicts 62 new driver candidates. Using a quantitative experimental framework to determine in vivo tumorigenic potential in mice, we found that Net......Sig candidates induce tumors at rates that are comparable to those of known oncogenes and are ten-fold higher than those of random genes. By reanalyzing nine tumor-inducing NetSig candidates in 242 patients with oncogene-negative lung adenocarcinomas, we find that two (AKT2 and TFDP2) are significantly amplified...

  11. 最大酸素摂取量(VO_2max)から推定するロングインターバルトレーニングの身体的影響 : 5000M走の場合

    OpenAIRE

    "榎本,豊/川上,雅之"; "エノモト,ユタカ/カワカミ,マサユキ"; "Enomoto,Yutaka/Kawakami,Masayuki"

    1990-01-01

    "The purpose of this study was analyis on the results of physical function affected by the long interval training of 5000 m run infered from maximal oxygen uptake (VO_2max). The subjects in this study were long distance runners (LD runners) of 5 male college students of 18 to 21. The influence of physical function was analyis by the results of heart rate (HR) during 5000 m run. The following results were obtained : 1) The mean of oxygen uptake (VO_2) during 5000 m run indicated the numerical ...

  12. WaterML, an Information Standard for the Exchange of in-situ hydrological observations

    Science.gov (United States)

    Valentine, D.; Taylor, P.; Zaslavsky, I.

    2012-04-01

    come to agreement on. This will be continued in future work for the HDWG, along with extending the information model to cover additional types of hydrologic information: rating and gauging information, and water quality. Rating curves, gaugings and river cross sections are commonly exchanged in addition to standard time-series data to allow information relating to conversions such as river level to discharge. Members of the HDWG plan to initiate this work in early 2012. Water quality data is varied in the way it is processed and in the number of phenomena it measures. It will require specific components of extension to the WaterML2.0 model, most likely making use of the specimen types within O&M and extensive use of controlled vocabularies. Other future work involves different target encodings for the WaterML2.0 conceptual model, such as JSON, netCDF, CSV etc. are optimized for particular needs, such as efficiency in size of the encoding and parsing of structure, but may not be capable of representing the full extent of the WaterML2.0 information model. Certain encodings are best matched for particular needs; the community has begun investigation into when and how best to implement these.

  13. TideNet

    Science.gov (United States)

    2015-10-30

    query tide data sources in a desired geographic region of USA and its territories (Figure 1). Users can select a tide data source through the Google Map ...select data sources according to the desired geographic region. It uses the Google Map interface to display data from different sources. Recent...Coastal Inlets Research Program TideNet The TideNet is a web-based Graphical User Interface (GUI) that provides users with GIS mapping tools to

  14. Building Neural Net Software

    OpenAIRE

    Neto, João Pedro; Costa, José Félix

    1999-01-01

    In a recent paper [Neto et al. 97] we showed that programming languages can be translated on recurrent (analog, rational weighted) neural nets. The goal was not efficiency but simplicity. Indeed we used a number-theoretic approach to machine programming, where (integer) numbers were coded in a unary fashion, introducing a exponential slow down in the computations, with respect to a two-symbol tape Turing machine. Implementation of programming languages in neural nets turns to be not only theo...

  15. Interaction Nets in Russian

    OpenAIRE

    Salikhmetov, Anton

    2013-01-01

    Draft translation to Russian of Chapter 7, Interaction-Based Models of Computation, from Models of Computation: An Introduction to Computability Theory by Maribel Fernandez. "In this chapter, we study interaction nets, a model of computation that can be seen as a representative of a class of models based on the notion of 'computation as interaction'. Interaction nets are a graphical model of computation devised by Yves Lafont in 1990 as a generalisation of the proof structures of linear logic...

  16. Programming NET 35

    CERN Document Server

    Liberty, Jesse

    2009-01-01

    Bestselling author Jesse Liberty and industry expert Alex Horovitz uncover the common threads that unite the .NET 3.5 technologies, so you can benefit from the best practices and architectural patterns baked into the new Microsoft frameworks. The book offers a Grand Tour" of .NET 3.5 that describes how the principal technologies can be used together, with Ajax, to build modern n-tier and service-oriented applications. "

  17. Method for the Thermal Characterization of PCM Systems in the Volume Range from 100 ml to 1000 ml

    Science.gov (United States)

    Göbel, A.; Vidi, S.; Klinker, F.; Hemberger, F.; Brütting, M.; Ebert, H.-P.; Mehling, H.

    2017-05-01

    The storage of latent heat in phase change materials (PCM) is of great interest in many applications, for example in building applications. However, there is no standard method for the determination of the thermophysical properties of application-sized PCM specimens, i.e., specimens with sizes around 100 ml to 1000 ml. In order to close this metrological gap, a commercially available heat flow meter was modified to perform enthalpy measurements. The feasibility of this method was proven by performing comparative measurements on a stainless steel specimen using both the standard method DSC and the modified heat flow meter. Furthermore, measurements on a gypsum board with microencapsulated PCM were performed with the heat flow meter in order to determine the enthalpy. The coincidence with literature values is within ±4% which demonstrates that this method is a good choice for performing measurements on application-sized PCM specimens.

  18. Synthesis and characterization of ML and ML2 metal complexes with amino acid substituted bis(2-picolyl)amine ligands.

    Science.gov (United States)

    Škalamera, Đani; Sanders, Ernest; Vianello, Robert; Maršavelski, Aleksandra; Pevec, Andrej; Turel, Iztok; Kirin, Srećko I

    2016-02-21

    Metal complexes with ML or ML2 stoichiometry have been isolated in the reaction of Zn(NO3)2, ZnBr2 or M(NO3)2/NaBF4, M = Zn(ii), Co(ii) or Ni(ii), with either amino acid or amine substituted tridentate nitrogen ligands based on bis(2-picolyl)amine (bpa) or bis(2-quinaldyl)amine (bqa). The stoichiometry (M : L = 1 : 1 or 1 : 2) and stereochemistry (mer, trans-fac or cis-fac) of the products have been studied by NMR and IR spectroscopy, X-ray single crystal analysis and quantum-chemical calculations with an implicit SMD solvation model.

  19. Cellular cardiac electrophysiology modeling with Chaste and CellML

    Science.gov (United States)

    Cooper, Jonathan; Spiteri, Raymond J.; Mirams, Gary R.

    2014-01-01

    Chaste is an open-source C++ library for computational biology that has well-developed cardiac electrophysiology tissue simulation support. In this paper, we introduce the features available for performing cardiac electrophysiology action potential simulations using a wide range of models from the Physiome repository. The mathematics of the models are described in CellML, with units for all quantities. The primary idea is that the model is defined in one place (the CellML file), and all model code is auto-generated at compile or run time; it never has to be manually edited. We use ontological annotation to identify model variables describing certain biological quantities (membrane voltage, capacitance, etc.) to allow us to import any relevant CellML models into the Chaste framework in consistent units and to interact with them via consistent interfaces. This approach provides a great deal of flexibility for analysing different models of the same system. Chaste provides a wide choice of numerical methods for solving the ordinary differential equations that describe the models. Fixed-timestep explicit and implicit solvers are provided, as discussed in previous work. Here we introduce the Rush–Larsen and Generalized Rush–Larsen integration techniques, made available via symbolic manipulation of the model equations, which are automatically rearranged into the forms required by these approaches. We have also integrated the CVODE solvers, a ‘gold standard’ for stiff systems, and we have developed support for symbolic computation of the Jacobian matrix, yielding further increases in the performance and accuracy of CVODE. We discuss some of the technical details of this work and compare the performance of the available numerical methods. Finally, we discuss how this is generalized in our functional curation framework, which uses a domain-specific language for defining complex experiments as a basis for comparison of model behavior. PMID:25610400

  20. A CellML simulation compiler and code generator using ODE solving schemes.

    Science.gov (United States)

    Punzalan, Florencio Rusty; Yamashita, Yoshiharu; Soejima, Naoki; Kawabata, Masanari; Shimayoshi, Takao; Kuwabara, Hiroaki; Kunieda, Yoshitoshi; Amano, Akira

    2012-10-19

    : Models written in description languages such as CellML are becoming a popular solution to the handling of complex cellular physiological models in biological function simulations. However, in order to fully simulate a model, boundary conditions and ordinary differential equation (ODE) solving schemes have to be combined with it. Though boundary conditions can be described in CellML, it is difficult to explicitly specify ODE solving schemes using existing tools. In this study, we define an ODE solving scheme description language-based on XML and propose a code generation system for biological function simulations. In the proposed system, biological simulation programs using various ODE solving schemes can be easily generated. We designed a two-stage approach where the system generates the equation set associating the physiological model variable values at a certain time t with values at t + Δt in the first stage. The second stage generates the simulation code for the model. This approach enables the flexible construction of code generation modules that can support complex sets of formulas. We evaluate the relationship between models and their calculation accuracies by simulating complex biological models using various ODE solving schemes. Using the FHN model simulation, results showed good qualitative and quantitative correspondence with the theoretical predictions. Results for the Luo-Rudy 1991 model showed that only first order precision was achieved. In addition, running the generated code in parallel on a GPU made it possible to speed up the calculation time by a factor of 50. The CellML Compiler source code is available for download at http://sourceforge.net/projects/cellmlcompiler.

  1. Simple ML Detector for Multiple Antennas Communication System

    Directory of Open Access Journals (Sweden)

    Ahmad Taqwa

    2010-10-01

    Full Text Available In order to support providing broadband wireless communication services against limited and expensive frequency bandwidth, we have to develop a bandwidth efficient system. Therefore, in this paper we propose a closed-loop MIMO (Multiple-Input-Multiple-Output system using ML (Maximum Likelihood detector to optimize capacity and to increase system performance. What is especially exciting about the benefits offered by MIMO is that a high capacity and performance can be attained without additional frequency-spectral resource. The grand scenario of this concept is the attained advantages of transformation matrices having capability to allocate transmitted signals power suit to the channel. Furthermore, product of these matrices forms parallel singular channels. Due to zero inter-channels correlation, thus we can design ML detector to increase the system performance. Finally, computer simulations validates that at 0 dB SNR our system can reach optimal capacity up to 1 bps/Hz and SER up to 0.2 higher than opened-loop MIMO.

  2. La plataforma .NET

    OpenAIRE

    Fornas Estrada, Miquel

    2008-01-01

    L'aparició de la plataforma .NET Framework ha suposat un canvi molt important en la forma de crear i distribuir aplicacions, degut a que incorpora una sèrie d'innovacions tècniques i productives que simplifiquen molt les tasques necessàries per desenvolupar un projecte. La aparición de la plataforma. NET Framework ha supuesto un cambio muy importante en la forma de crear y distribuir aplicaciones, debido a que incorpora una serie de innovaciones técnicas y productivas que simplifican mucho...

  3. Biological Petri Nets

    CERN Document Server

    Wingender, E

    2011-01-01

    It was suggested some years ago that Petri nets might be well suited to modeling metabolic networks, overcoming some of the limitations encountered by the use of systems employing ODEs (ordinary differential equations). Much work has been done since then which confirms this and demonstrates the usefulness of this concept for systems biology. Petri net technology is not only intuitively understood by scientists trained in the life sciences, it also has a robust mathematical foundation and provides the required degree of flexibility. As a result it appears to be a very promising approach to mode

  4. Clinical application of l-123 MlBG cardiac imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Do Young [College of Medicine, Donga Univ., Busan (Korea, Republic of)

    2004-10-01

    Cardiac neurotransmission imaging allows in vivo assessment of presynaptic reuptake, neurotransmitter storage and postsynaptic receptors. Among the various neurotransmitter, I-123 MlBG is most available and relatively well-established. Metaiodobenzylguanidine (MIBG) is an analogue of the false neurotransmitter guanethidine. It is taken up to adrenergic neurons by uptake-1 mechanism as same as norepinephrine. As tagged with I-123, it can be used to image sympathetic function in various organs including heart with planar or SPECT techniques. I-123 MIBG imaging has a unique advantage to evaluate myocardial neuronal activity in which the heart has no significant structural abnormality or even no functional derangement measured with other conventional examination. In patients with cardiomyopathy and heart failure, this imaging has most sensitive technique to predict prognosis and treatment response of betablocker or ACE inhibitor. In diabetic patients, it allow very early detection of autonomic neuropathy. In patients with dangerous arrhythmia such as ventricular tachycardia or fibrillation, MIBG imaging may be only an abnormal result among various exams. In patients with ischemic heart disease, sympathetic derangement may be used as the method of risk stratification. In heart transplanted patients, sympathetic reinnervation is well evaluated. Adriamycin-induced cardiotoxicity is detected earlier than ventricular dysfunction with sympathetic dysfunction. Neurodegenerative disorder such as Parkinson's disease or dementia with Lewy bodies has also cardiac sympathetic dysfunction. Noninvasive assessment of cardiac sympathetic nerve activity with l-123 MlBG imaging may be improve understanding of the pathophysiology of cardiac disease and make a contribution to predict survival and therapy efficacy.

  5. The Native Plasmid pML21 Plays a Role in Stress Tolerance in Enterococcus faecalis ML21, as Analyzed by Plasmid Curing Using Plasmid Incompatibility.

    Science.gov (United States)

    Zuo, Fang-Lei; Chen, Li-Li; Zeng, Zhu; Feng, Xiu-Juan; Yu, Rui; Lu, Xiao-Ming; Ma, Hui-Qin; Chen, Shang-Wu

    2016-02-01

    To investigate the role of the native plasmid pML21 in Enterococcus faecalis ML21's response to abiotic stresses, the plasmid pML21 was cured based on the principle of plasmid incompatibility and segregational instability, generating E. faecalis mutant strain ML0. The mutant and the wild strains were exposed to abiotic stresses: bile salts, low pH, H2O2, ethanol, heat, and NaCl, and their survival rate was measured. We found that curing of pML21 lead to reduced tolerance to stress in E. faecalis ML0, especially oxidative and osmotic stress. Complementation analysis suggested that the genes from pML21 played different role in stress tolerance. The result indicated that pML21 plays a role in E. faecalis ML21's response to abiotic stresses.

  6. Petri Nets-Applications

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 9. Petri Nets - Applications. Y Narahari. General Article Volume 4 Issue 9 September 1999 pp 44-52. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/004/09/0044-0052. Author Affiliations. Y Narahari ...

  7. Safety nets or straitjackets?

    DEFF Research Database (Denmark)

    Ilsøe, Anna

    2012-01-01

    Does regulation of working hours at national and sector level impose straitjackets, or offer safety nets to employees seeking working time flexibility? This article compares legislation and collective agreements in the metal industries of Denmark, Germany and the USA. The industry has historically...

  8. Coloured Petri Nets

    CERN Document Server

    Jensen, Kurt

    2009-01-01

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. This book introduces the constructs of the CPN modelling language and presents the related analysis methods. It provides a comprehensive road map for the practical use of CPN.

  9. Boom Booom Net Radio

    DEFF Research Database (Denmark)

    Grimshaw, Mark Nicholas; Yong, Louisa; Dobie, Ian

    1999-01-01

    of an existing Internet radio station; Boom Booom Net Radio. Whilst necessity dictates some use of technology-related terminology, wherever possible we have endeavoured to keep such jargon to a minimum and to either explain it in the text or to provide further explanation in the appended glossary....

  10. Game Theory .net.

    Science.gov (United States)

    Shor, Mikhael

    2003-01-01

    States making game theory relevant and accessible to students is challenging. Describes the primary goal of GameTheory.net is to provide interactive teaching tools. Indicates the site strives to unite educators from economics, political and computer science, and ecology by providing a repository of lecture notes and tests for courses using…

  11. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt; Kristensen, Lars Michael

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. The development of such systems is particularly challenging because of inherent intricacies like possible nondeterminism...

  12. Nanoscale Phase Separation and Lattice Complexity in VO2: The Metal–Insulator Transition Investigated by XANES via Auger Electron Yield at the Vanadium L23-Edge and Resonant Photoemission

    Directory of Open Access Journals (Sweden)

    Augusto Marcelli

    2017-12-01

    Full Text Available Among transition metal oxides, VO2 is a particularly interesting and challenging correlated electron material where an insulator to metal transition (MIT occurs near room temperature. Here we investigate a 16 nm thick strained vanadium dioxide film, trying to clarify the dynamic behavior of the insulator/metal transition. We measured (resonant photoemission below and above the MIT transition temperature, focusing on heating and cooling effects at the vanadium L23-edge using X-ray Absorption Near-Edge Structure (XANES. The vanadium L23-edges probe the transitions from the 2p core level to final unoccupied states with 3d orbital symmetry above the Fermi level. The dynamics of the 3d unoccupied states both at the L3- and at the L2-edge are in agreement with the hysteretic behavior of this thin film. In the first stage of the cooling, the 3d unoccupied states do not change while the transition in the insulating phase appears below 60 °C. Finally, Resonant Photoemission Spectra (ResPES point out a shift of the Fermi level of ~0.75 eV, which can be correlated to the dynamics of the 3d// orbitals, the electron–electron correlation, and the stability of the metallic state.

  13. Fine Structure and Instability of the Ml-a Locus in Barley

    OpenAIRE

    Wise, Roger P.; Ellingboe, Albert H.

    1985-01-01

    There are many naturally occurring variants at the Ml-a locus in barley that confer resistance to the powdery mildew fungus Erysiphe graminis f. sp. hordei. Since the Ml-a locus is bracketed by Hor-1 and Hor-2, genes that encode storage proteins in the endosperm, the Ml-a locus is amenable to fine structure analysis. Rare susceptible recombinants, as judged by exchange of flanking markers, were recovered in F3 families from the Ml-a10 x Ml-a1, Ml-a1 x Ml-a15 and Ml-a6 x Ml-a13 crosses. Some...

  14. Coloured Petri Nets: Basic Concepts, Analysis Methods and Practical Use. Vol. 3, Practical Use

    DEFF Research Database (Denmark)

    Jensen, Kurt

    system and related work. I have edited the material provided by the o