Asteroid rotation rates

The dependence of rotational frequency on diameter, taxonomic type, and family membership is analyzed for 217 main-belt asteroids with statistically useful periods extracted from the file published by Harris and Young ((1983). Icarus54, 59–109). It is shown that for asteroids with diameters ? 120 km, mean rotational frequency increases with increasing diameter. This trend is equally present in all subsets of M-, S-, and C-type asteroids, for both family and nonfamily members alike, and cannot be accounted for by observational selection. For asteroids with diameters ? 120 km, mean rotational frequency increases with decreasing diameter; however, within this group there is a subset of asteroids with exceptionally long rotational periods. This marked change in the distribution at diameter ～ 120 km could separate primordial asteroids from their collision products. However, it is probable that the sample is biased in favor of small asteroids with short rotational periods and that the apparent increase of mean rotational frequency with decreasing diameter for small asteroids is at least partly the product of observational selection. An observational program that could test this hypothesis is described. If asteroids of any one diameter are considered, then, on average, M asteroids rotate faster than S asteroids which in turn rotate faster than C asteroids. This shows that asteroids which have been classified by their surface properties alone have different bulk properties. There is also some evidence that for all asteroidal types, of all diameters, family members rotate faster than nonfamily members.     

EVALUATING THE STABILITY OF OUTDOOR RECREATION PARTICIPATION MODELS*

Application of forecasting models reveals that parameter estimates vary substantially among regions reflecting spatial variation in consumer preferences and behavior. We present a simulation methodology to evaluate the stability in performance of recreation participation models between different regions. The sample data consisted of 632 household interviews obtained via random digit dialing techniques as part of Oklahoma's 1980 statewide survey of outdoor recreation demand. Three variables, the age of the head of the household, the number of household members, and distance to the facility were consistently accurate predictors of participation; the performance of other variables depended directly upon unknown attributes of the specific region.     

CLIMATOLOGY OF PRECIPITATION DROUGHTS IN ILLINOIS BASED ON WATER SUPPLY PROBLEMS

Drought begins with a reduction in precipitation, but different kinds of precipitation deficiency episodes (duration, intensity, and areal extent) create varying problems for drought-sensitive activities; an agricultural droughttypically is not a water supply drought. Shared characteristics of precipitation deficiency events and related surface water supply problems in Illinois were used to define climatological characteristics of precipitation deficiency droughts that cause problems for water supply systems. The temporal and spatial characteristics of these water supply precipitation droughts were assessed revealing that droughts typically: (a) begin in warm season months; (b) become more widespread when more severe and/or of shorter duration (although all droughts could be expected to cover at least 75%-85% of the state); (c) are more severe and frequent in central Illinois; and (d) end with much above normal precipitation in the initial post-drought months, but tend to recess to slightly drier than normal conditions (but not drought levels).     

Socioeconomic impact of oil in Nigeria

Taxes and royalties from the oil industry in Nigeria have made possible massive infrastructural and social development throughout the country; this single industry continues to be the most important contributor to the national treasury. Along with oil, however, have come environmental and social problems, some severe and, in the social sector, possibly of long duration. Questionnaires were employed to solicit environmental and socioeconomic information from residents in the oil-impacted area as well as to ascertain the views of the oil companies with respect to their Nigerian operations, in particular to their socio-economic responsibilities to the local residents. Responses point to serious discontent on the part of the impacted population, especially in the most important southern (Niger Delta) oil producing region. These negative attitudes in part are based upon the impacted population’s inability to secure for itself a sufficiently large number of oil industry jobs and in part to the presence in the local community of ethnic strangers who do have such employment. There is evidence of serious environmental damage, but its biological dimension has been overshadowed by claims for monetary compensation at the local level. Data derived from these investigations might well be applicable in the wider field of trans-national mining and petroleum extraction operations in developing countries, especially to the unwritten social obligations of the expatriate firm to local residents.     

Variations of bromide in potable ground water in the United States

Concentrations of bromide in potable ground water that has <10 mg/L chloride range from 0.0032 to 0.058 mg/L with a median value of 0.016 mg/L. The chloride/bromide mass ratio for the same water ranges from 43 to 285 with a median value of 101. The ratios, which resulted from screening approximately 165 analyses of water from 32 locations in 24 states in the United States, show a distinct geographic variation with highest values near the coast and trending toward a value of approximately 50 in the continental interior.     

Correlations among the parameters of the spherical model for eclipsing binaries

Correlation coefficients have been computed to investigate the parameters used to describe the spherical model of an eclipsing binary system. Regions in parameter hyperspace have been identified where strong correlations exist and, by implication, the solution determinacy is low. The results are presented in tabular form for a large number of system configurations.Originally presented at the IAU Colloquium No. 16, held at the University of Pennsylvania, Philadeiphia, Pa, U.S.A., September 8–11, 1971.     

Assessing the spatial distribution of crop areas using a cross-entropy method

While crop production statistics are reported on a geopolitical – often national – basis, we often need to know, for example, the status of production or productivity within specific sub-regions, watersheds, or agro-ecological zones. Such re-aggregations are typically made using expert judgments or simple area-weighting rules. We describe a new, entropy-based approach to the plausible estimates of the spatial distribution of crop areas. Using this approach tabular crop production statistics are blended judiciously with an array of other secondary data to assess the areas of specific crops within individual ‘pixels’—typically 25–100 km² in size. The information utilized includes crop production statistics, farming system characterization, satellite-based interpretation of land cover, biophysical crop suitability assessments, and population density. An application is presented in which Brazilian state level production statistics are used to generate pixel level crop area data for eight crops. To validate the spatial allocation we aggregated the pixel estimates to obtain synthetic estimates of municipality level areas in Brazil, and compared those estimates with actual municipality statistics. The approach produced extremely promising results. We then examined the robustness of these results compared to simplified approaches to spatializing crop production statistics and showed that, while computationally intensive, the cross-entropy method does provide more reliable spatial allocations.