5,736 research outputs found
Large-scale, near-Earth, magnetic fields from external sources and the corresponding induced internal field
Data from MAGSAT analyzed as a function of the Dst index to determine the first degree/order spherical harmonic description of the near-Earth external field and its corresponding induced field. The analysis was done separately for data from dawn and dusk. The MAGSAT data was compared with POGO data. A local time variation of the external field persists even during very quiet magnetic conditions; both a diurnal and 8-hour period are present. A crude estimate of Sq current in the 45 deg geomagnetic latitude range is obtained for 1966 to 1970. The current strength, located in the ionosphere and induced in the Earth, is typical of earlier determinations from surface data, although its maximum is displaced in local time from previous results
Use of collateral information to improve LANDSAT classification accuracies
There are no author-identified significant results in this report
Equivalent source modeling of the main field using MAGSAT data
An iterative least squares estimation algorithm with the capability for including a priori statistical information was implemented to recover multiple magnetic dipole models of the Earth's main magnetic field. The dipoles are fixed to a specified radius at or below the core-mantle boundary and centered on equal area blocks. The algorithm can solve for dipole magnitudes only (fixed orientations), or allow full freedom of orientation and solve for vector components. External field parameters and observatory anomaly biases can also be estimated simultaneously. Time dependence is modeled using first time derivatives for dipole vector components. Single-epoch and time dependent dipole models are derived using MAGSAT and observatory annul means data. Equivalent spherical harmonic representation are computed in closed form from the dipole models and compared with truncated spherical harmonic models estimated in the standard way from the same data sets. In particular, a 21 deg spatial resolution model based on 93 dipoles was computed based on observatory annual means data and a selected MAGSAT data set and was compared with candidate IGRF 1975 models and their 1980 secular variation
PRICE, QUALITY, AND PESTICIDE RELATED HEALTH RISK CONSIDERATIONS IN FRUIT AND VEGETABLE PURCHASES: AN HEDONIC ANALYSIS OF TUCSON, ARIZONA SUPERMARKETS
National opinion polls indicate that pesticide residues on fresh fruits and vegetables remain an important concern of American consumers, despite a decade-long increase in per capita consumption levels for fresh fruits and vegetables. Increased availability of organically grown fruits and vegetables may change consumer produce purchase behavior which is often dominated by appearance considerations. Domestic consumers likely consider and tradeoff price, visual appearance, and health risk when buying fresh produce. This paper uses an hedonic framework to examine price, appearance, and health risk considerations made by Tucson, Arizona shoppers in 1994.Consumer/Household Economics, Demand and Price Analysis,
Domain general learning: Infants use social and non-social cues when learning object statistics.
Previous research has shown that infants can learn from social cues. But is a social cue more effective at directing learning than a non-social cue? This study investigated whether 9-month-old infants (N = 55) could learn a visual statistical regularity in the presence of a distracting visual sequence when attention was directed by either a social cue (a person) or a non-social cue (a rectangle). The results show that both social and non-social cues can guide infants' attention to a visual shape sequence (and away from a distracting sequence). The social cue more effectively directed attention than the non-social cue during the familiarization phase, but the social cue did not result in significantly stronger learning than the non-social cue. The findings suggest that domain general attention mechanisms allow for the comparable learning seen in both conditions
Comparison and contrast in perceptual categorization
People categorized pairs of perceptual stimuli that varied in both category membership and pairwise similarity. Experiments 1 and 2 showed categorization of 1 color of a pair to be reliably contrasted from that of the other. This similarity-based contrast effect occurred only when the context stimulus was relevant for the categorization of the target (Experiment 3). The effect was not simply owing to perceptual color contrast (Experiment 4), and it extended to pictures from common semantic categories (Experiment 5). Results were consistent with a sign-and-magnitude version of N. Stewart and G. D. A. Brown's (2005) similarity-dissimilarity generalized context model, in which categorization is affected by both similarity to and difference from target categories. The data are also modeled with criterion setting theory (M. Treisman & T. C. Williams, 1984), in which the decision criterion is systematically shifted toward the mean of the current stimuli
A PERFORMANCE EVALUATION OF FIVE SWEETPOTATO SHIPPING CONTAINERS
Using a six x six latin square experimental design, five box types in two different markets were evaluated over a six-week period in 1986 to determine if sweetpotato arrival damage could be reduced through use of alternative shipping containers. Findings indicated that skinning, cut and break damage, and bruising could be reduced through use of either a 40-pound container or the 45-pound MUM box rather than using the current 50-pound box. Economic considerations, receiver preferences, and the actions of shippers resulted in the selection of a 40-pound shipping carton as the new standard for the North Carolina sweetpotato industry.Agribusiness,
Ultrasonic estimates of muscle and fat thickness in live cattle as predictors of carcass yield
The purposes of this study were to determine the relationships between both linear and ultrasonic measurements in84 live beef steers and carcass composition. Fat thickness over the longissimus dorsimeasured ultrasonically was positively related to retail cuts weight but negatively related to retail cuts percent, accounting for about 35 percent of the variance. Biceps femoris muscle depths tended to have higher associations with cutout measures than did longissimus dorsior infraspinatus muscle depths. Live weight, which was used in all multiple regression equations, generally accounted for a larger amount of the variance in carcass composition than any other single measurement. Estimated round mass (alinear measurement, beginning at the tail, then encircling the leg and continuing to the dorsal midline between the hooks) and live weight were of significant value in pre-2 dieting round separable muscle weights (R2 =0.58). Live Weight and either estimated round mass or Biceps femoris muscle depth were the most accurate predictors of round separable muscle weight. Biceps femoris depth and live weight were the most effective estimators of retail cuts weight. Fat thickness over the longissimus dorsiand live weight were the only variables which had a significant effect in predicting percent retail cuts. In conclusion, these predictions of carcass composition were sufficiently accurate and valid for steers, but should not be used on heifers or bulls without further testing
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