Peak oxygen deficit predicts sprint and middle-distance track performance

The purpose of this study was to determine the value of the peak oxygen deficit (POD) as a predictor of sprint and middle-distance track performance. POD, peak blood lactate, VO2peak, lactate threshold, and running economy at 3.6 m.s-1 were measured during horizontal treadmill running in 22 male and 19 female competitive runners of different event specialties. Subjects also completed running performance trials at 100, 200, 400, 800, 1500, and 5000 m. Correlations of track performances with POD (ml.kg-1) (-0.66, -0.71, -0.71, -0.62, -0.52, and -0.40) were moderately strong at the sprint and middle distances, accounting for 44-50% of the performance variance at the three shortest distances. Correlations of track performances with peak blood lactate concentration were lower than with POD and accounted for approximately one-half as much of the performance variance (21-26%) at the three shortest distances. Multiple regression analyses indicated that the POD was the strongest metabolic predictor of 100-, 200- and 400-m performance, and that VO2peak was the strongest metabolic predictor of 800-, 1500-, and 5000-m performance. We conclude that the POD is a moderately strong predictor of sprint and middle-distance track performance.     

Immunogenicity of synthetic HIV-1 gp120 V3-loop peptide-conjugate immunogens

A successful prophylactic human immunodeficiency virus type 1 (HIV-1) vaccine must elicit an immune response that will prevent establishment of the persistent viral infection. The only response shown to be effective in this regard is virus-neutralizing antibody directed against the viral gp120 hypervariable V3-loop region. Conjugate immunogens, containing cyclic peptides representing the V3 determinant covalently bound to a carrier protein, were capable of eliciting virus-neutralizing antibodies. The consistency of the response was related to peptide size. The smaller cyclic peptides, expressing relatively conserved sequences from the V3-loop apex, were poor inducers of neutralizing activity. In contrast, the largest cyclic peptides mediated neutralizing responses that were similar to those observed and previously reported for intact gp120 immunogens. A cyclic synthetic peptide expressing most of the prototypic HIV-1 MN variant V3 determinant warrants further study as a potentially effective vaccine immunogen.     

Price elasticity of the demand for water in Southern California

Summary In summary, we can state that econometric evidence suggests an elasticity of -.35 for household uses in Southern California. This is comprised of elasticities of -.24 and -.7 for inside and outside uses respectively.The data on industrial demand is less evident, but suggests an elasticity of well above -1.0 for low prices of water, that is, before recirculation systems have been installed. Only those using ground water or brackish water are paying prices around 5¢ per thousand gallons or $15 per acre-foot (Prices here mean the cost of pumping and sometimes for a pumping tax of acquiring such water.). If these industries should begin paying marginal costs of supplying water, then we can expect a substantial reduction in water consumption by them as they use recirculation systems. For industries which derive water from municipal supplies, they are already paying relatively high prices for water and therefore have already initiated water saving devices. For them the price elasticity is probably quite low, around -.2 or highly inelastic.In agriculture, with substantial opportunity for factor substitution, but less than expected possibilities of pricing crops out of production, an elasticity of-.5 seems appropriate, although this figure must be interpreted with caution as the data is just not available to confirm this estimate.Combining the above, the fresh-water demand for water will be in the neighborhood of -.3, as municipal demands are the dominant factor determining demand in Southern California. An elasticity of -.3 which is actually rather close to previous studies, is still less elastic than most. However, these conclusions must be tentative awaiting the results of another half year of study on a very complex market for water.The Author is Lecturer in the Department of Economics, University of California, Los Angeles.     

A simulation-based design paradigm for complex cast components

This paper describes and exercises a new design paradigm for cast components. The methodology integrates foundry process simulation, non-destructive evaluation (NDE), stress analysis and damage tolerance simulations into the design process. Foundry process simulation is used to predict an array of porosity-related anomalies. The probability of detection of these anomalies is investigated with a radiographic inspection simulation tool (XRSIM). The likelihood that the predicted array of anomalies will lead to a failure is determined by a fatigue crack growth simulation based on the extended finite element method and therefore does not require meshing nor remeshing as the cracks grow. With this approach, the casting modeling provides initial anomaly information, the stress analysis provides a value for the critical size of an anomaly and the NDE assessment provides a detectability measure. The combination of these tools allows for accept/reject criteria to be determined at the early design stage and enables damage tolerant design philosophies. The methodology is applied to the design of a cast monolithic door used on the Boeing 757 aircraft.     

Wavelength shift analysis: a simple method to determine the contribution of hemoglobin and myoglobin to in vivo optical spectra

The ability to quantify the contributions of hemoglobin (Hb) and myoglobin (Mb) to in vivo optical spectra has many applications for clinical and research use such as noninvasive measurement of local tissue O(2) uptake rates and regional blood content. Recent work has demonstrated an approach to independently measure oxygen saturations of Hb and Mb in optical spectra collected in vivo. However, the utility of this approach is limited without information on tissue concentrations of these species. Here we describe a strategy to quantify the contributions of Hb and Mb to in vivo optical spectra. We have found that the peak position of the deoxy-heme peak around 760 nm in the optical spectra of the deoxygenated tissue is a linear function of the relative contributions of Hb and Mb to the optical spectra. Therefore, analysis of this peak position, hereafter referred to as wavelength shift analysis, reveals the relative concentration of Hb to Mb in solutions and intact tissue. Biochemical analysis of muscle homogenates confirmed that the wavelength shift of the combined Hb/Mb peak in in vivo spectra reflects the ratio of concentrations (Hb/Mb) in muscle. The importance of quantifying the Hb contribution is illustrated by our data demonstrating that Hb accounts for approximately 80% of the optical signal in mouse skeletal muscle but only approximately 20% in human skeletal muscle. This advance will facilitate comparison of the metabolic properties between individual muscles and provides a fully noninvasive approach to measuring local respiration that can be adapted for clinical use.     

Short-term methane emissions from 2 dairy farms in California estimated by different measurement techniques and US Environmental Protection Agency inventory methodology: A case study

Reported estimates of CH₄ emissions from ruminants and manure management are up to 2 times higher in atmospheric top-down calculations than in bottom-up (BU) inventories. We explored this discrepancy by estimating CH₄ emissions of 2 dairy facilities in California with US Environmental Protection Agency (US EPA) methodology, which is used for BU inventories, and 3 independent measurement techniques: (1) open-path measurements with inverse dispersion modeling (hereafter open-path), (2) vehicle measurements with tracer flux ratio method, and (3) aircraft measurements with the closed-path method. All 3 techniques were used to estimate whole-facility CH₄ emissions during 3 to 6 d per farm in the summer of 2016. In addition, open-path was used to estimate whole-facility CH₄ emissions over 13 to 14 d per farm in the winter of 2017. Our objectives were to (1) compare whole-facility CH₄ measurements utilizing the different measurement techniques, (2) compare whole-facility CH₄ measurements to US EPA inventory methodology estimates, and (3) compare CH₄ emissions between 2 dairies. Whole-facility CH₄ estimates were similar among measurement techniques. No seasonality was detected for CH₄ emissions from animal housing, but CH₄ emissions from liquid manure storage were 3 to 6 times greater during the summer than during the winter measurement periods. The findings confirm previous studies showing that whole-facility CH₄ emissions need to be measured throughout the year to estimate and evaluate annual inventories. Open-path measurements for liquid manure storage emissions were similar to monthly US EPA estimates during the summer, but not during the winter measurement periods. However, the numerical difference was relatively small considering yearly emission estimates. Manure CH₄ emissions contributed 69 to 79% and 26 to 47% of whole-facility CH₄ emissions during the summer and winter measurement periods, respectively. Methane yields from animal housing were similar between farms (on average 20.9 g of CH₄/kg of dry matter intake), but CH₄ emissions normalized by volatile solids (VS) loading from liquid manure storage (g of CH₄ per day/kg of VS produced by all cattle per day) at 1 dairy were 1.7 and 3.5 times greater than at the other during the summer (234 vs. 137 g of CH₄/kg of VS) and winter measurement periods (78 vs. 22 g of CH₄/kg of VS), respectively. We attributed much of this difference to the proportion of manure stored in liquid (anaerobic) form, and suggest that manure management practices that reduce the amount of manure solids stored in liquid form could significantly reduce dairy CH₄ emissions.     

Enhancing Organic Semiconductor Molecular Packing Using Perovskite Interfaces to Improve Singlet Fission

Singlet fission, a process by which one singlet exciton is converted into two lower energy triplet excitons, is sensitive to the degree of electronic coupling within a molecular packing structure. Variations in molecular packing can be detrimental to triplet formation and triplet–triplet separation, ultimately affecting the harvesting of triplets for electricity in organic photovoltaic devices. Here, six phase-pure molecular packing structures of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) with varying optoelectronic properties are isolated using 2D lead halide perovskites as tunable, crystalline surfaces for crystallization. Transient absorption spectroscopy reveals that while triplet formation is fast (<100 fs) regardless of template structure, the increased ordering in perovskite-templated samples speeds up triplet–triplet separation and recombination, providing evidence that the benefits of phase-purity offset minor variations in molecular packing. Molecular dynamics modeling of the interface reveals that perovskite-templating allows for closer packing of TIPS-pentacene molecules for all perovskite templates. With an extensive number of organic molecule-perovskite pairings, this work provides a methodology to use ordered, periodic surfaces to elucidate structure–property relationships of small organic molecules in order to adjust structural or optoelectronic responses, such as molecular packing and singlet fission.