Sex Differences in Elite Swimming with Advanced Age Are Less Than Marathon Running

The sex difference in marathon performance increases with finishing place and age of the runner but whether this occurs among swimmers is unknown. The purpose was to compare sex differences in swimming velocity across world record place (1st–10th), age group (25–89 years), and event distance. We also compared sex differences between freestyle swimming and marathon running. The world\u27s top 10 swimming times of both sexes for World Championship freestyle stroke, backstroke, breaststroke, and butterfly events and the world\u27s top 10 marathon times in 5-year age groups were obtained. Men were faster than women for freestyle (12.4 ± 4.2%), backstroke (12.8 ± 3.0%), and breaststroke (14.5 ± 3.2%), with the greatest sex differences for butterfly (16.7 ± 5.5%). The sex difference in swimming velocity increased across world record place for freestyle (P \u3c 0.001), breaststroke, and butterfly for all age groups and distances (P  \u3c 0.001) because of a greater relative drop-off between first and 10th place for women. The sex difference in marathon running increased with the world record place and the sex difference for marathon running was greater than for swimming (P \u3c 0.001). The sex difference in swimming increased with world record place and age, but was less than for marathon running. Collectively, these results suggest more depth in women\u27s swimming than marathon running

Modeling space-time correlations of velocity fluctuations in wind farms

An analytical model for the streamwise velocity space-time correlations in turbulent flows is derived and applied to the special case of velocity fluctuations in large wind farms. The model is based on the Kraichnan-Tennekes random sweeping hypothesis, capturing the decorrelation in time while including a mean wind velocity in the streamwise direction. In the resulting model, the streamwise velocity space-time correlation is expressed as a convolution of the pure space correlation with an analytical temporal decorrelation kernel. Hence, the spatio-temporal structure of velocity fluctuations in wind farms can be derived from the spatial correlations only. We then explore the applicability of the model to predict spatio-temporal correlations in turbulent flows in wind farms. Comparisons of the model with data from a large eddy simulation of flow in a large, spatially periodic wind farm are performed, where needed model parameters such as spatial and temporal integral scales and spatial correlations are determined from the large eddy simulation. Good agreement is obtained between the model and large eddy simulation data showing that spatial data may be used to model the full temporal structure of fluctuations in wind farms.Comment: Submitted to Wind Energ

Geomorphology of the middle Mississippi River

DBS-SAS-MAS 9.Includes bibliographical references (pages 79-80).Prepared for U.S. Army Engineer Waterways Experiment Station, Corps of Engineers, Vicksburg, Mississippi under Contract No. DACW39-73-C- 0026 by Engineering Research Center, Colorado State University, Fort Collins, Colorado.January 1974.Sponsored by U.S. Army Engineer District, St. Louis

Spatio-temporal spectra in the logarithmic layer of wall turbulence: large-eddy simulations and simple models

Motivated by the need to characterize the spatio-temporal structure of turbulence in wall-bounded flows, we study wavenumber-frequency spectra of the streamwise velocity component based on large-eddy simulation (LES) data. The LES data are used to measure spectra as a function of the two wall-parallel wavenumbers and the frequency in the equilibrium (logarithmic) layer. We then reformulate one of the simplest models that is able to reproduce the observations: the random sweeping model with a Gaussian large-scale fluctuating velocity and with additional mean flow. Comparison with LES data shows that the model captures the observed temporal decorrelation, which is related to the Doppler broadening of frequencies. We furthermore introduce a parameterization for the entire wavenumber-frequency spectrum $E_{11}(k_1,k_2,\omega;z)$, where $k_1$, $k_2$ are the streamwise and spanwise wavenumbers, $\omega$ is the frequency and $z$ is the distance to the wall. The results are found to be in good agreement with LES data

Covering California's Kids: The Impact of Healthy Kids on Access, Health Status and Costs

Summarizes how the implementation of CHIs designed to improve children's access to primary care helped reduce preventable hospitalizations among lower-income children. Includes policy implications

Flood protection at culvert outlets

CER69-70DBS-MAS-FJW4.Includes bibliographical references (pages 59-60).Prepared for Wyoming State Highway Department, Planning and Research Division in cooperation with the U.S. Department of Transportation, Federal Highway Administration, Bureau of Public Roads.In this study several classes of information concerning flood protection at culvert outlets are presented. The information is related to the flow conditions at culvert outfalls and to the hydraulics of rigid basins and outlet basins stabilized with rock riprap. In addition, the characteristics of high tailwater and non-scouring, low tailwater basins are covered. In this report it is intended that a hydraulic engineer can take the information contained in the text, examples, illustrations, and figures and apply it toward the design of an energy dissipator of maximum effectiveness. The data on which the report is based were gathered mostly during an experimental program at Colorado State University. In some cases, adequate data were available from other sources. Where such information was needed, it was incorporated into the report

National Park Service Visitation and Search Behavior: An Update to 2010

Abstract This purpose of this paper was to examine and update recent findings that proposes that national park visitation is on the decline and to propose other methods for examining the interest in national parks through online searches related to travel intentions. Data from a large, national syndicated secondary dataset were examined by individual participation data collected on an annual basis over the period of 2000-2010. In addition, inquiry data from Google Insights™ for vacation travel to national and state parks was also used as a proxy measure to determine if interest had declined. While there was evidence of some decline in visitation to national parks from 2000-2010, most of the decline was limited to the period of 2000-2004; however, there was also a rebound in interest from 2004 through 2010 with the exception of 2008. The decline does not appear to be dramatic. The decline is not related to a decrease in the market size of individuals interested in national parks but rather a volume issue. The volume issue suggests that the base market of people interested in national parks still exists, but the base market is making fewer visits per visitor to national parks. Additional insights into visitation based on media use (e.g., watching tv and internet use) based on volume segments were explored. There was some indication of decline of interest in visiting national parks during vacation travel through the analysis of Google Insights™ search behavior; however, this decline has been cyclical, not overly dramatic, and appears to reflect the changes in visitation noted here through the national syndicated dataset findings. Interest may also have shifted to other outdoor pursuits and interests via an increase in more choices. Interest in state parks appeared to also be seasonal; but no dramatic decline in the interest in state parks was noted based on Internet searches and Google Insights™ analysis

A zone of preferential ion heating extends tens of solar radii from Sun

The extreme temperatures and non-thermal nature of the solar corona and solar wind arise from an unidentified physical mechanism that preferentially heats certain ion species relative to others. Spectroscopic indicators of unequal temperatures commence within a fraction of a solar radius above the surface of the Sun, but the outer reach of this mechanism has yet to be determined. Here we present an empirical procedure for combining interplanetary solar wind measurements and a modeled energy equation including Coulomb relaxation to solve for the typical outer boundary of this zone of preferential heating. Applied to two decades of observations by the Wind spacecraft, our results are consistent with preferential heating being active in a zone extending from the transition region in the lower corona to an outer boundary 20-40 solar radii from the Sun, producing a steady state super-mass-proportional $\alpha$-to-proton temperature ratio of $5.2-5.3$. Preferential ion heating continues far beyond the transition region and is important for the evolution of both the outer corona and the solar wind. The outer boundary of this zone is well below the orbits of spacecraft at 1 AU and even closer missions such as Helios and MESSENGER, meaning it is likely that no existing mission has directly observed intense preferential heating, just residual signatures. We predict that {Parker Solar Probe} will be the first spacecraft with a perihelia sufficiently close to the Sun to pass through the outer boundary, enter the zone of preferential heating, and directly observe the physical mechanism in action.Comment: 11 pages, 7 figures, accepted for publication in the Astrophysical Journal on 1 August 201