Manned Mars mission cost estimate

The potential costs of several options of a manned Mars mission are examined. A cost estimating methodology based primarily on existing Marshall Space Flight Center (MSFC) parametric cost models is summarized. These models include the MSFC Space Station Cost Model and the MSFC Launch Vehicle Cost Model as well as other modes and techniques. The ground rules and assumptions of the cost estimating methodology are discussed and cost estimates presented for six potential mission options which were studied. The estimated manned Mars mission costs are compared to the cost of the somewhat analogous Apollo Program cost after normalizing the Apollo cost to the environment and ground rules of the manned Mars missions. It is concluded that a manned Mars mission, as currently defined, could be accomplished for under $30 billion in 1985 dollars excluding launch vehicle development and mission operations

Characterization of plankton from the Galveston estuary

The purpose of this report is to summarize the published studies on phytoplankton and zooplankton in the Galveston Estuary. Before this project had begun, it was determined that there was insufficient long term data on plankton in the Galveston Estuary to attempt trend analysis. Information on phytoplankton species diversity, biomass and primary production, along with information on zooplankton species diversity and abundance, is summarized. This information is compared to similar data on other Texas and United States estuaries where available. Recommendations for a long term monitoring program are made. A bibliography of all Galveston Estuary plankton studies and an annotated bibliography of the major studies and publications are available in the GBNEP Information Center.Marine Scienc

Rounding in Recreation Demand Models: A Latent Class Count Model

A commonly observed feature of visitation data, elicited via a survey instrument, is a greater propensity for individuals to report trip numbers that are multiples of 5's, relative to other possible integers (such as 3 or 6). One explanation of this phenomenon is that some survey respondents have difficulty recalling the exact number of trips taken and instead choose to round their responses. This paper examines the impact that rounding can have on the estimated demand for recreation and the bias that it may induce on subsequent welfare estimates. We propose the use of a latent class structure in which respondents are assumed to be members of either a nonrounding or a rounding class. A series of generated data experiments are provided to illustrate the range of possible impacts that ignoring rounding can have on the estimated parameters of the model and on the welfare implications from site closure. The results suggest that biases can be substantial, particularly when then unconditional mean number of trips is in the range from two to four. An illustrative application is provided using visitation data to Saylorville Lake in central Iowa.recreation demand; count data; rounding

Private Crop Insurers and the Reinsurance Fund Allocation Decision

This research investigates the strategic behavior of private crop insurance firms reinsured by the USDA through the Standard Reinsurance Agreement. This arrangement allows the private firm to strategically allocate individual policies into different risk sharing arrangements. Thus, firm earnings are conditioned upon accurately forecasting policy loss experience. Our analysis begins with models investigating the characteristics explaining the placement of policies into the assigned risk fund. Then a simulation model of the SRA is used to compare the post-SRA returns of actual firm allocations to two alternative allocation strategies based on aggregate models and a policy-level econometric forecasting model.Risk, insurance, reinsurance, logit, policy

A Platform for Proactive, Risk-Based Slope Asset Management, Phase II

INE/AUTC 15.0

Neutron stars and white dwarfs in galactic halos

The possibility that galactic halos are composed of stellar remnants such as neutron stars and white dwarfs is discussed. On the basis of a simple model for the evolution of galactic halos, researchers follow the history of halo matter, luminosity, and metal and helium abundances. They assume conventional yields for helium and the heavier elements. By comparing with the observational constraints, which may be considered as fairly conservative, it is found that, for an exponentially decreasing star formation rate (SFR) with e-folding time tau, only values between 6 x 10(8) less than similar to tau less than similar to 2 x 10(9) years are allowed together with a very limited range of masses for the initial mass function (IMF). Star formation is allowed for 2 solar mass less than similar to m less than similar to 8 solar mass if tau = 2 x 10(9) years, and for 4 solar mass less than similar to m less than similar to 6 solar mass if tau = 10(9) years. For tau = 6 x 10(8) years, the lower and upper mass limits merge to similar to 5 solar mass. Researchers conclude that, even though the possibility of neutron stars as halo matter may be ruled out, that of white dwarfs may still be a viable hypothesis, though with very stringent constraints on allowed parameters, that merits further consideration

Cosmic Chemical Evolution with an Early Population of Intermediate Mass Stars

We explore the consequences of an early population of intermediate mass stars in the 2 - 8 M\odot range on cosmic chemical evolution. We discuss the implications of this population as it pertains to several cosmological and astrophysical observables. For example, some very metal-poor galactic stars show large enhancements of carbon, typical of the C-rich ejecta of low-mass stars but not of supernovae; moreover, halo star carbon and oxygen abundances show wide scatter, which imply a wide range of star-formation and nucleosynthetic histories contributed to the first generations of stars. Also, recent analyses of the 4He abundance in metal-poor extragalactic H II regions suggest an elevated abundance Yp \simeq 0.256 by mass, higher than the predicted result from big bang nucleosynthesis assuming the baryon density determined by WMAP, Yp = 0.249. Although there are large uncertainties in the observational determination of 4He, this offset may suggest a prompt initial enrichment of 4He in early metal-poor structures. We also discuss the effect of intermediate mass stars on global cosmic evolution, the reionization of the Universe, the density of white dwarfs, as well as SNII and SNIa rates at high redshift. We also comment on the early astration of D and 7Li. We conclude that if intermediate mass stars are to be associated with Population III stars, their relevance is limited (primarily from observed abundance patterns) to low mass structures involving a limited fraction of the total baryon content of the Universe.Comment: Submitted to MNRA

Evaluation of rapid reading hay moisture meters for field use

An instrument for use by farmers and agricultural research workers to quickly, accurately, and economically determine the moisture content of hay in the windrow would significantly improve the efficiency of forage crop production. However, no method or technique has been shown to be a successful tool for obtaining such determinations simply, precisely, and with easily portable equipment. An experiment was desig-nated to field test a commercially available conductance-type moisture meter and to identify needed revisions of the meter or a measuring technique that might improve its accuracy. An experimental conductance-type meter was also built and tested in an attempt to develop a more accurate method for hay moisture content measurements. Three electrical moisture meters, a hydraulic compression device, sample probe, hay sample chopper, and other related swithing gear were purchased or designed and constructed. The meters were tested on three different hay types, at various sample pressures, and at two geographical locations. The performance of the meters was compared to oven drying moisture determinations. Results of these series of tests revealed several factors which affect the accuracy of the meters as determined from simple linear regression equations relating meter readings to actual hay moisture content. 1. The use of a cylindrical holder eliminated error caused by the prod pins completely penetrating the windrowed hay and entering the soil surface. 2. Sample pressure affected meter readings. No specific pressure was best overall, but a constant pressure was mandatory for consistent results. 3. Fields, type of crop, or time of test also affected meter readings and calibration equations. 4. Chopping of hay samples improved the accuracy and consistency of meter readings. 5. No one single meter proved to be statistically better than the others tested

Sire by environment interactions for growth traits in beef cattle

The importance of region by sire, herd within region by sire and contemporary group within herd by sire interactions were evaluated for 68,271 birth weight, 247,943 weaning weight and 98,790 postweaning gain records supplied by the American Polled Hereford Association. Variance components for sire, region by sire, herd within region by sire, contemporary group within herd by sire and error were estimated using Henderson Method 3 estimation procedures. Sire by region, herd within region by sire and contemporary group within herd by sire variance estimates divided by the sire variance estimates were .57, .93 and 1.71, respectively, for weaning weight, -1.00, -.14 and 1.29, respectively, for birth weight, and -1.19, .14 and 1.22, respectively, for postweaning gain;The average genetic correlation estimates of weaning weight sire expected differences (EPDs) across regions was .64. This value expresses the correlation among progeny of the same sire after the sire evaluation model had accounted for the contemporary group within herd by sire and herd within region by sire interactions. The average genetic correlation estimates of weaning weight sire EPDs across contemporary groups within herds and across herds within regions were .37 and .27, respectively. The correlation estimates indicated that some rank changes were occurring between sire EPDs in different regions, and substantial rank changes of sire EPDs were occurring across herd and contemporary groups. Heritability of weaning weight was .11 across regions, .17 across herds within region, .28 within herd, and .46 within contemporary group;The average genetic correlation estimates among birth weight sire EPDs across regions were .24 and .35 using two different estimation methods. The average genetic correlation estimates among postweaning gain sire EPDs across regions were .21 and .32 using two different estimation methods. The correlation estimates for birth weight and postweaning gain may not fully reflect the true nature of the correlations due to insufficient number of progreny across regions;In general, contemporary group within herd by sire interaction appeared to be an important source of variation for all the traits and should continue to be included as a random effect in future national sire evaluations for the Polled Hereford breed. The data also indicated that performing sire evaluations across regions for birth weight, weaning weight and postweaning gain, while assuming that region by sire effects are negligible, may lead to severe errors in ranking sires in some regions. Separate sire evaluations for each region would yield sire estimates that better reflect the true future progeny performance of a sire in each region