The Mississippian fin de siècle in the middle Cumberland region of Tennessee

Bayesian chronological modeling is used to investigate the chronology for a large-scale human depopulation event during the Mississippian period (AD 1000–1600) known as the Vacant Quarter phenomenon. The Middle Cumberland region (MCR) of Tennessee is within the Vacant Quarter area, and six villages from the final phase of Mississippian activity in the MCR have been subjected to radiocarbon dating. Complete radiocarbon datasets from these sites are presented within an interpretative Bayesian statistical framework. The results provide a unique history of each settlement and demonstrate that Mississippian occupations at each site likely terminated in the mid- to late fifteenth and possibly early sixteenth centuries AD, which is 50 to 100 years later than the most recent estimate for the timing of the Vacant Quarter. Mississippian abandonment in the MCR was relatively quick, likely occurring over less than a century. The exact reasons for abandonment are not entirely clear but appear to be linked to climate change. A radiocarbon simulation experiment indicates that future robust radiocarbon dating with well-selected samples could greatly improve the chronological precision for this late Mississippian activity. More broadly, this example demonstrates that model building with radiocarbon simulations can be used to address regional-scale chronological issues within the American Southeast and beyond

Statistical distribution of mechanical properties for three graphite-epoxy material systems

Graphite-epoxy composites are playing an increasing role as viable alternative materials in structural applications necessitating thorough investigation into the predictability and reproducibility of their material strength properties. This investigation was concerned with tension, compression, and short beam shear coupon testing of large samples from three different material suppliers to determine their statistical strength behavior. Statistical results indicate that a two Parameter Weibull distribution model provides better overall characterization of material behavior for the graphite-epoxy systems tested than does the standard Normal distribution model that is employed for most design work. While either a Weibull or Normal distribution model provides adequate predictions for average strength values, the Weibull model provides better characterization in the lower tail region where the predictions are of maximum design interest. The two sets of the same material were found to have essentially the same material properties, and indicate that repeatability can be achieved

Strange resonance poles from KπK\pi scattering below 1.8 GeV

In this work we present a determination of the mass, width and coupling of the resonances that appear in kaon-pion scattering below 1.8 GeV. These are: the much debated scalar $\kappa$-meson, nowdays known as $K_0^*(800)$, the scalar $K_0^*(1430)$, the $K^*(892)$ and $K_1^*(1410)$ vectors, the spin-two $K_2^*(1430)$ as well as the spin-three $K^*_3(1780)$. The parameters will be determined from the pole associated to each resonance by means of an analytic continuation of the $K\pi$ scattering amplitudes obtained in a recent and precise data analysis constrained with dispersion relations, which were not well satisfied in previous analyses. This analytic continuation will be performed by means of Pad\'e approximants, thus avoiding a particular model for the pole parameterization. We also pay particular attention to the evaluation of uncertainties.Comment: 13 pages, 12 figures. Accepted version to appear in Eur. Phys. J. C. Clarifications and references added, minor typos correcte

Atlas of electron content values observed at Urbana, Illinois, 1 December 1967 - 30 December 1970

Ionospheric electron content versus local time data deduced from Faraday rotation observations of ATS-III geostationary satellite signals at Urbana, Illinois are reported. The data are presented in two forms. Values of subionospheric latitude (SILAT) and subionospheric longitude (SILON) are in degrees north and degrees west, respectively. These are computed on the basis of 350 km for the mean ionospheric height, which value is also used for the calculation of the geometric-magnetic factor, required for the conversion of the measured Faraday rotation angle to electron content. Entries of zero for the electron content in the tables represent no data for those times

Automating Satellite Range Scheduling

The objective of this study was to develop a computer based satellite range scheduling SRS algorithm to create a 24 hour satellite support schedule. The algorithms goal was to schedule as many satellite support requests as possible. An iterative heuristic approach was used to schedule satellite support requests in three successive sub problems. The first sub problem involves scheduling low altitude satellite support requests using a mixed integer programming approach. The next two sub problems each involve scheduling 12 hour blocks of medium and high altitude satellite support requests, again using a mixed integer programming approach. Fourteen 24 hour schedules were generated using actual data with encouraging results. At least 95 percent of the satellite support requests were scheduled for each day. These results are in-line with results obtained by range schedulers and previous studies. Because of the promising results, this algorithm may be used to automate a portion of the satellite range scheduling problem

The Effect of Cycling Moisture Content on the Lateral Load Carrying Capacity of Three Member Nailed Wood Joints

This study was designed to investigate the effect of cyclic moisture changes on the strength of three member nailed wood joints. The construction material used consisted of Douglas fir construction grade 2-inch by 4-inch main members and splice plates of 3/8-inch and 5/8-inch exterior Douglas fir plywood. Nails were placed in single shear and double shear with the two sizes of splice plates. Nail sizes were 6d bright common, 8d bright common, and 8d bright ring shank. Specimens with various combinations of splice plate thickness and nail sizes were constructed with single shear and double shear being considered. The specimens were separated into two series: constant moisture series and cycling moisture series. A statistical analysis was performed on the observed data in two phases: (a) an estimating equation, standard deviation, standard error of estimate, unexplained variation, explained variation, and coefficient of correlation were determined for load versus time, (b) the results of the first analysis indicated “pooling” of data in groups was possible, therefore a t-test and an analysis of variance was performed on the means of the cycling and constant moisture series to indicated whether or not a significant difference existed between the two series

Multi-Frequency Study of the B3-VLA Sample II. The Database

We present total flux densities of 1049 radio sources in the frequency range from 151 MHz to 10.6 GHz. These sources belong to the B3-VLA sample, which is complete down to 100 mJy at 408 MHz. The data constitute a homogeneous spectral database for a large sample of radio sources, 50 times fainter than the 3C catalogue, and will be used to perform a spectral ageing analysis, which is one of the critical points in understanding the physics and evolution of extragalactic radio sources.Comment: 14 pages, 3 figures, accepted for publication in Astronomy & Astrophysics Supplement Series, gzipped postscript file also available at http://multivac.jb.man.ac.uk:8000/ceres/papers/papers.html or http://gladia.astro.rug.nl:8000/ceres/papers/papers.htm

Shuttle environmental and thermal control/life support system computer program

Computer programs developed to simulate the RSECS (representative shuttle environmental control system) are described. These programs were prepared to provide pretest predictions, post-test analysis and real-time problem analysis for RSECS test planning and evaluation. These programs are on a magnetic tape cassette and on a disc device that is part of the WANG-2200 series computer system