Comparison of Post-Activation Potentiating Stimuli on Jump and Sprint Performance

Post-activation potentiation (PAP) is a phenomenon characterized by improved muscle performance based on the previous contractile activity of the muscle. The purpose of this study was to determine the effect of different potentiating stimuli on jump and sprint performance in 13 resistance trained, college-aged men and women. After determining back squat 1 repetition max, subjects returned for testing on separate days to complete one of four interventions (dynamic resistance, weighted plyometric, isometric, or control) in a randomized order. A standardized warmup was performed, followed by a baseline countermovement jump (CMJ) and 20m sprint. Following warm-up and baseline measurements, subjects performed one of the four experimental conditions. CMJ and 20m sprint measurements were completed again at 20-seconds, 4, 8, 12, 16, and 20-minutes. Results revealed significantly faster 0-20m sprint times (p \u3c .05) at the 4, 8, 12, 16, and 20-minute time points compared to baseline and 20-second time points. Significantly faster 0-20m sprint times (p \u3c .05) were also shown for the squat intervention compared to control at 4-minutes, the plyometric and squat intervention compared to control at 8-minutes, the isometric intervention compared to control at 12 and 16- minutes, and the isometric intervention compared to the squat at 20-minutes. These findings indicate that while all PAP stimuli utilized can be effective at improving sprint performance, specific optimal time points may exist

Ground Contact Time Imbalances Strongly Related to Impaired Running Economy

Running economy (RE) is defined as the oxygen consumption (VO2) or caloric unit cost required to move at a specific velocity and is an important performance marker. Ground contact time (GCT) has been associated with RE; however, it has not been established how GCT imbalances between feet impact RE. Purpose: Determine the relationship between cadence, GCT, and GCT imbalances and RE. Methods: 11 NCAA Division I distance runners (7 male) completed a graded exercise test on a treadmill to determine lactate threshold (LT) and VO2max. Body composition was also assessed via DEXA. Subjects ran with a heart rate monitor capable of measuring cadence, GCT, and GCT balance between feet. VO2 and respiratory exchange ratio were recorded over the last minute of the 5-minute stages. RE expressed as caloric unit cost (kcal·kg-1· km-1) was calculated for the stage determined to be just below the LT (prior to \u3e 4mmol/L) and was correlated with cadence, GCT, and GCT imbalance by Pearson correlations. Results: Pearson correlations between RE and the running dynamics measures were as follows: cadence (r = -.444, p = .171), GCT (r = .492, p = .125), GCT Imbalance (r = .808, p \u3c .005). An independent t-test revealed greater (p = .023) leg lean mass imbalances in runners with larger GCT imbalances compared to runners with smaller GCT imbalances. Conclusion: GCT imbalances are strongly related to impaired RE. Future research should determine how to improve GCT imbalances and if doing so improves RE

Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV

We present the first measurement of the inclusive three-jet differential cross section as a function of the invariant mass of the three jets with the largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96 TeV. The measurement is made in different rapidity regions and for different jet transverse momentum requirements and is based on a data set corresponding to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at the Fermilab Tevatron Collider. The results are used to test the three-jet matrix elements in perturbative QCD calculations at next-to-leading order in the strong coupling constant. The data allow discrimination between parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected chi2 values for NNPD

Impact of vital signs screening & clinician prompting on alcohol and tobacco screening and intervention rates: a pre-post intervention comparison

<p>Abstract</p> <p>Background</p> <p>Though screening and intervention for alcohol and tobacco misuse are effective, primary care screening and intervention rates remain low. Previous studies have increased intervention rates using vital signs screening for tobacco misuse and clinician prompts for screen-positive patients for both alcohol and tobacco misuse. This pilot study's aims were: (1) To determine the feasibility of combined vital signs screening for tobacco and alcohol misuse, (2) To assess the impact of vital signs screening on alcohol and tobacco screening and intervention rates, and (3) To assess the additional impact of tobacco assessment prompts on intervention rates.</p> <p>Methods</p> <p>In five outpatient practices, nurses measuring vital signs were trained to routinely ask a single tobacco question, a prescreening question that identified current drinkers, and the single alcohol screening question for current drinkers. After 4-8 weeks, clinicians were trained in tobacco intervention and nurses were trained to give tobacco abusers a tobacco questionnaire which also served as a clinician intervention prompt. Screening and intervention rates were measured using patient exit interviews (n = 622) at baseline, during the "screening only" period, and during the tobacco prompting phase. Changes in screening and intervention rates were compared using chi square analyses and test of linear trends. Clinic staff were interviewed regarding patient and staff acceptability. Logistic regression was used to evaluate the impact of nurse screening on clinician intervention, the impact of alcohol intervention on concurrent tobacco intervention, and the impact of tobacco intervention on concurrent alcohol intervention.</p> <p>Results</p> <p>Alcohol and tobacco screening rates and alcohol intervention rates increased after implementing vital signs screening (p < .05). During the tobacco prompting phase, clinician intervention rates increased significantly for both alcohol (12.4%, p < .001) and tobacco (47.4%, p = .042). Screening by nurses was associated with clinician advice to reduce alcohol use (OR 13.1; 95% CI 6.2-27.6) and tobacco use (OR 2.6; 95% CI 1.3-5.2). Acceptability was high with nurses and patients.</p> <p>Conclusions</p> <p>Vital signs screening can be incorporated in primary care and increases alcohol screening and intervention rates. Tobacco assessment prompts increase both alcohol and tobacco interventions. These simple interventions show promise for dissemination in primary care settings.</p

Measurement of the differential cross section for the production of an isolated photon with associated jet in ppbar collisions at sqrt(s)=1.96 TeV

The process ppbar -> photon + jet + X is studied using 1.0 fb^-1 of data collected by the D0 detector at the Fermilab Tevatron ppbar collider at a center-of-mass energy sqrt(s)=1.96 TeV. Photons are reconstructed in the central rapidity region |y_gamma|<1.0 with transverse momenta in the range 30<Pt_gamma<400 GeV while jets are reconstructed in either the central |y_jet|15 GeV. The differential cross section d^3sigma/dPt_gamma dy_gamma dy_jet is measured as a function of Pt_gamma in four regions, differing by the relative orientations of the photon and the jet in rapidity. Ratios between the differential cross sections in each region are also presented. Next-to-leading order QCD predictions using different parameterizations of parton distribution functions and theoretical scale choices are compared to the data. The predictions do not simultaneously describe the measured normalization and Pt_gamma dependence of the cross section in any of the four measured regions.Comment: 13 pages, 10 figure

ICAR: endoscopic skull‐base surgery

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Running Economy Strongly Related to Ground Contact Time Imbalances

Running economy (RE) can be defined as the oxygen consumption or caloric unit cost required to move at a specific velocity. In addition to a runner’s maximal oxygen uptake (VO2max) and lactate threshold (LT), RE is a key endurance performance determinant. Better RE is advantageous as it represents the ability to run at a lower relative percentage of VO2max at a given speed and reduces the rate of energy depletion. Ground contact time (GCT) has been associated with RE, however it has not been established how GCT imbalances between feet impact economy. Purpose: Determine the relationship between cadence, GCT, and GCT imbalances and RE. Methods: 11 NCAA Division I distance runners (7 male: 21±2 years, 15.8±3.4% fat; 4 female: 19±1 years, 22.1±5.2% fat) completed a graded exercise test on a treadmill to determine LT and VO2max. Subjects ran with a heart rate monitor capable of measuring cadence, GCT, and GCT balance between left and right feet. VO2 and the respiratory exchange ratio (RER) were monitored continuously, and the average VO2 and RER over the last minute of the 5 minute stages was used for determining caloric cost. Caloric unit cost (kcal·kg-1·km-1) was calculated for the stage determined to be just below the LT (prior to \u3e4mmol/L) and the relationship between this measure of RE was correlated with cadence, GCT, and GCT imbalance by Pearson correlations. Results: The average VO2max among the runners was 68.6±4.9 ml·kg-1·min-1 and 59.3±1.1 ml·kg-1·min-1, and the average LT was 80±8% and 83±5% VO2max for men and women, respectively. The Pearson correlations between the caloric cost of running (kcal·kg-1·km-1) and the listed running dynamics measure were as follows: cadence (r = -.454, p = .161), GCT (r = .492, p = .124), GCT Imbalance (r = .874, p \u3c .001). There was a very strong, positive correlation between GCT imbalances and the caloric cost of running. Conclusion: Previous research has linked GCT and cadence to running economy, but to our knowledge GCT imbalances have not been previously investigated. These data show that GCT imbalances were a stronger determinant of RE than GCT or cadence. Future research should determine how to improve GCT imbalances and if doing so can improve economy and performance

Directed Evolution of Pyruvate Decarboxylase-Negative Saccharomyces cerevisiae, Yielding a C(2)-Independent, Glucose-Tolerant, and Pyruvate-Hyperproducing Yeast

The absence of alcoholic fermentation makes pyruvate decarboxylase-negative (Pdc(−)) strains of Saccharomyces cerevisiae an interesting platform for further metabolic engineering of central metabolism. However, Pdc(−) S. cerevisiae strains have two growth defects: (i) growth on synthetic medium in glucose-limited chemostat cultures requires the addition of small amounts of ethanol or acetate and (ii) even in the presence of a C(2) compound, these strains cannot grow in batch cultures on synthetic medium with glucose. We used two subsequent phenotypic selection strategies to obtain a Pdc(−) strain without these growth defects. An acetate-independent Pdc(−) mutant was obtained via (otherwise) glucose-limited chemostat cultivation by progressively lowering the acetate content in the feed. Transcriptome analysis did not reveal the mechanisms behind the C(2) independence. Further selection for glucose tolerance in shake flasks resulted in a Pdc(−) S. cerevisiae mutant (TAM) that could grow in batch cultures (μ(max) = 0.20 h(−1)) on synthetic medium, with glucose as the sole carbon source. Although the exact molecular mechanisms underlying the glucose-tolerant phenotype were not resolved, transcriptome analysis of the TAM strain revealed increased transcript levels of many glucose-repressible genes relative to the isogenic wild type in nitrogen-limited chemostat cultures with excess glucose. In pH-controlled aerobic batch cultures, the TAM strain produced large amounts of pyruvate. By repeated glucose feeding, a pyruvate concentration of 135 g liter(−1) was obtained, with a specific pyruvate production rate of 6 to 7 mmol g of biomass(−1) h(−1) during the exponential-growth phase and an overall yield of 0.54 g of pyruvate g of glucose(−1)

Hierarchical heterogeneity at the CeOx-TiO2 interface: Electronic and geometric structural influence on the photocatalytic activity of oxide on oxide nanostructures

Mixed oxide interfaces are critical for delivering active components of demanding catalytic processes such as the photocatalytic splitting of water. We have studied CeOx–TiO2 catalysts with low ceria loadings of 1, 3, and 6 wt % that were prepared with wet impregnation methods to favor a strong interaction between CeOx and TiO2. In these materials the interfaces between CeOx–TiO2 have been sequentially loaded (1%, 3%, and 6%), with and without Pt (0.5 wt %). The structure and properties of the catalysts were characterized using several X-ray and electron based techniques including XRD, XPS, UPS, NEXAFS, UV–vis, and HR-STEM/STEM-EELS to unravel the local morphology, bulk structure, surface states, and electronic structure. The combination of all these techniques allows us to analyze in a systematic way the complete structural and electronic properties that prevail at the CeOx–TiO2 interface. Fluorite structured nanocrystallites of ceria on anatase-structured titania were identified by both XRD and NEXAFS. A sequential increase of the CeOx loading led to the formation of clusters, then plates, and finally nanoparticles in a hierarchical manner on the TiO2 support. The electronic structures of these catalysts indicate that the interaction between TiO2 and CeO2 is closely related to the local morphology of nanostructured CeO2. Ce3+ cations were detected at the surface of CeO2 and at the interface of the two oxides. In addition, the titania is perturbed by the interaction with ceria and also with Pt. The photocatalytic activity for the splitting of H2O using UV light was measured for these materials and correlated with our understanding of the electronic and structural properties. Optimal catalytic performance and photoresponse results were found for the 1 wt % CeOx–TiO2 catalyst where low dimensional geometry of the ceria provided ideal electronic and geometrical properties. The structural and electronic properties of the interface were critical for the photocatalytic performance of this mixed-oxide nanocatalyst system.The research carried out in this manuscript was performed at Brookhaven National Laboratory, supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, and Catalysis Science Program under Contract DE-SC0012704. L.B. also acknowledges financial support from the JAE-CSIC grant programPeer Reviewe

Hierarchical Heterogeneity at the CeO_<i>x</i>–TiO₂ Interface: Electronic and Geometric Structural Influence on the Photocatalytic Activity of Oxide on Oxide Nanostructures

Mixed oxide interfaces are critical for delivering active components of demanding catalytic processes such as the photocatalytic splitting of water. We have studied CeO_<i>x</i>–TiO₂ catalysts with low ceria loadings of 1, 3, and 6 wt % that were prepared with wet impregnation methods to favor a strong interaction between CeO_<i>x</i> and TiO₂. In these materials the interfaces between CeO_<i>x</i>–TiO₂ have been sequentially loaded (1%, 3%, and 6%), with and without Pt (0.5 wt %). The structure and properties of the catalysts were characterized using several X-ray and electron based techniques including XRD, XPS, UPS, NEXAFS, UV–vis, and HR-STEM/STEM-EELS to unravel the local morphology, bulk structure, surface states, and electronic structure. The combination of all these techniques allows us to analyze in a systematic way the complete structural and electronic properties that prevail at the CeO_<i>x</i>–TiO₂ interface. Fluorite structured nanocrystallites of ceria on anatase-structured titania were identified by both XRD and NEXAFS. A sequential increase of the CeO_<i>x</i> loading led to the formation of clusters, then plates, and finally nanoparticles in a hierarchical manner on the TiO₂ support. The electronic structures of these catalysts indicate that the interaction between TiO₂ and CeO₂ is closely related to the local morphology of nanostructured CeO₂. Ce³⁺ cations were detected at the surface of CeO₂ and at the interface of the two oxides. In addition, the titania is perturbed by the interaction with ceria and also with Pt. The photocatalytic activity for the splitting of H₂O using UV light was measured for these materials and correlated with our understanding of the electronic and structural properties. Optimal catalytic performance and photoresponse results were found for the 1 wt % CeO_<i>x</i>–TiO₂ catalyst where low dimensional geometry of the ceria provided ideal electronic and geometrical properties. The structural and electronic properties of the interface were critical for the photocatalytic performance of this mixed-oxide nanocatalyst system