Nonmetro Recreation Counties: Their Identification and Rapid Growth

More than 80 percent of the Nation’s 285 million people now reside in metropolitan areas. Many in this vast city and suburban population are attracted to the recreational opportunities and attractions of rural areas, such as beautiful scenery, lakes, mountains, forests, and resorts. For rural communities struggling to offset job losses from farming, mining, and manufacturing, capitalizing on the recreational appeal of an area fosters economic development, attracts new residents, and retains existing population. This article outlines a method to identify nonmetro counties with high recreation development. It then examines the linkage between such development and population change, and considers its implications for the future of rural and small-town America

Moving to Diversity

In this brief, authors Richelle Winkler and Kenneth Johnson, using new data and techniques, find that net migration between U.S. counties increased racial diversity in each of the last two decades. However, migration’s influence on diversity was far from uniform: it varied by race, age group, and location, sometimes starkly. Overall, net migration of the population under age 40 increased diversity, while net migration of people over age 60 diminished diversity. Blacks and Hispanics are migrating to predominantly white counties, while white young adults are moving to urban core counties with relatively high proportions of blacks and Hispanics. The movement of older whites is not contributing to the growing diversity, because older whites tend to move to predominantly white counties. Winkler and Johnson conclude that, while migration contributed to the growing diversity of the nation, the process was complex and varied from place to place with significant social, economic, and political implications for both the more diverse and less diverse places

Deaths Exceed Births in Most of Europe, But Not in the United States

In this brief, authors Kenneth Johnson, Layton Fields, and Dudley Poston, Jr. present important new findings about the diminishing number of births compared to deaths in Europe and the United States from their recent article in Population and Development Review. Their research focuses on the prevalence and dynamics of natural decrease in subareas of Europe and the United States in the first decade of the twenty-first century using counties (United States) or county-equivalents (Europe). The authors report that 58 percent of the 1,391 counties of Europe had more deaths than births during that period compared to just 28 percent of the 3,137 U.S. counties. Natural decrease is more widespread in Europe because its population is older, fertility rates are lower, and there are fewer women of child-bearing age. Natural decrease is a major policy concern because it drains the demographic resilience from a region, diminishing its economic viability and competitiveness. The implications of the recent European immigrant surge for natural decrease are uncertain, but the authors’ analysis suggests that natural decrease is likely to remain widespread in Europe for the foreseeable future

Carbon Fiber Strand Tensile Failure Dynamic Event Characterization

There are few if any clear, visual, and detailed images of carbon fiber strand failures under tension useful for determining mechanisms, sequences of events, different types of failure modes, etc. available to researchers. This makes discussion of physics of failure difficult. It was also desired to find out whether the test article-to-test rig interface (grip) played a part in some failures. These failures have nothing to do with stress rupture failure, thus representing a source of waste for the larger 13-00912 investigation into that specific failure type. Being able to identify or mitigate any competing failure modes would improve the value of the 13-00912 test data. The beginnings of the solution to these problems lay in obtaining images of strand failures useful for understanding physics of failure and the events leading up to failure. Necessary steps include identifying imaging techniques that result in useful data, using those techniques to home in on where in a strand and when in the sequence of events one should obtain imaging data

A method for calculating 16o/18o peptide ion ratios for the relative quantification of proteomes

AbstractA method is described for the identification and relative quantification of proteomes using accurate mass tags (AMT) generated by nLC-dual ESI-FT-ICR-MS on a 7T instrument in conjunction with stable isotope labeling using 16O/18O ratios. AMTs were used for putative peptide identification, followed by confirmation of peptide identity by tandem mass spectrometry. For a combined set of 58 tryptic peptides from bovine serum albumin (BSA) and human transferrin, a mean mass measurement accuracy of 1.9 ppm ±0.94 ppm (CIM99%) was obtained. This subset of tryptic peptides was used to measure 16O/18O ratios of 0.36 ± 0.09 (CIM99%) for BSA (μ = 0.33) and 1.48 ± 0.47 (CIM99%) for transferrin (μ = 1.0) using a method for calculating 16O/18O ratios from overlapping isotopic multiplets arising from mixtures of 16O, 18O1, and 18O2 labeled C-termini. The model amino acid averagine was used to calculate a representative molecular formula for estimating and subtracting the contributions of naturally occurring isotopes solely as a function of peptide molecular weight. The method was tested against simulated composite 16O/18O spectra where peptide molecular weight, 16O/18O ratio, 18O1/18O2 ratios, and number of sulfur atoms were varied. Relative errors of 20% or less were incurred when the 16O/18O ratios were less than three, even for peptides where the number of sulfur atoms was over- or under-estimated. These data demonstrate that for biomarker discovery, it is advantageous to label the proteome representing the disease state with 18O; and the method is not sensitive to variations in 18O1/18O2 ratio. This approach allows a comprehensive differentiation of expression levels and tentative identification via AMTs, followed by targeted analysis of over- and under-expressed peptides using tandem mass spectrometry, for applications such as the discovery of disease biomarkers

Moving to Diversity

America is growing more racially and ethnically diverse, yet some parts of the country are far more diverse than others. Migration—the flow of people from one place to another—influences local diversity by continually redistributing the population and altering the racial mix in both the sending and receiving communities. Migration can serve an integrating function when people from different races move into the same area, but it can also reinforce existing racial boundaries and diminish local diversity when people from different racial groups sort themselves into homogeneous communities

Emperical Tests of Acceptance Sampling Plans

Acceptance sampling is a quality control procedure applied as an alternative to 100% inspection. A random sample of items is drawn from a lot to determine the fraction of items which have a required quality characteristic. Both the number of items to be inspected and the criterion for determining conformance of the lot to the requirement are given by an appropriate sampling plan with specified risks of Type I and Type II sampling errors. In this paper, we present the results of empirical tests of the accuracy of selected sampling plans reported in the literature. These plans are for measureable quality characteristics which are known have either binomial, exponential, normal, gamma, Weibull, inverse Gaussian, or Poisson distributions. In the main, results support the accepted wisdom that variables acceptance plans are superior to attributes (binomial) acceptance plans, in the sense that these provide comparable protection against risks at reduced sampling cost. For the Gaussian and Weibull plans, however, there are ranges of the shape parameters for which the required sample sizes are in fact larger than the corresponding attributes plans, dramatically so for instances of large skew. Tests further confirm that the published inverse-Gaussian (IG) plan is flawed, as reported by White and Johnson (2011)

Colonization and Predation in Isolated Seagrass Beds: An Experimental Assessment From the Northern Gulf of Mexico

We tested the effects of habitat fragmentation on the structure (community composition and biomass) and function (predation rates as assessed by tethering) of circular artificial seagrass units (ASUs) located in an area removed from the influence of immigrants from established seagrass meadows. ASUs varied by size (0.1-10 m2), perimeter, and perimeter:area ratios (P/A). Blue crabs and hermit crabs accounted for the greatest number of individuals and biomass present on the ASUs, but amphipods, shrimps, fishes, and gastropods were also present. We detected few significant relationships between abundance or biomass and patch size, perimeter, or P/A ratios. In tethering experiments, there were no significant differences in mortality among the different sized ASUs in any of the three tethering locations, but there was significantly less pinfish mortality in the ASU center as compared to the patch edge and unstructured sand habitats. Our results suggest that although community composition may be dissimilar to areas with established seagrass meadows, the ecological responses to habitat fragmentation remain constant. These data can provide a better understanding of faunal assemblages that can be expected for restored seagrass beds in areas without established seagrass populations

Probabilistic Requirements (Partial) Verification Methods Best Practices Improvement. Variables Acceptance Sampling Calculators: Empirical Testing

The NASA Engineering and Safety Center was requested to improve on the Best Practices document produced for the NESC assessment, Verification of Probabilistic Requirements for the Constellation Program, by giving a recommended procedure for using acceptance sampling by variables techniques as an alternative to the potentially resource-intensive acceptance sampling by attributes method given in the document. In this paper, the results of empirical tests intended to assess the accuracy of acceptance sampling plan calculators implemented for six variable distributions are presented

Probabilistic Requirements (Partial) Verification Methods Best Practices Improvement. Variables Acceptance Sampling Calculators: Derivations and Verification of Plans

The NASA Engineering and Safety Center was requested to improve on the Best Practices document produced for the NESC assessment, Verification of Probabilistic Requirements for the Constellation Program, by giving a recommended procedure for using acceptance sampling by variables techniques. This recommended procedure would be used as an alternative to the potentially resource-intensive acceptance sampling by attributes method given in the document. This document contains the outcome of the assessment