7,004 research outputs found
Magnetic Gimbal Proof-of-Concept Hardware performance results
The Magnetic Gimbal Proof-of-Concept Hardware activities, accomplishments, and test results are discussed. The Magnetic Gimbal Fabrication and Test (MGFT) program addressed the feasibility of using a magnetic gimbal to isolate an Electro-Optical (EO) sensor from the severe angular vibrations induced during the firing of divert and attitude control system (ACS) thrusters during space flight. The MGFT effort was performed in parallel with the fabrication and testing of a mechanically gimballed, flex pivot based isolation system by the Hughes Aircraft Missile Systems Group. Both servo systems supported identical EO sensor assembly mockups to facilitate direct comparison of performance. The results obtained from the MGFT effort indicate that the magnetic gimbal exhibits the ability to provide significant performance advantages over alternative mechanically gimballed techniques
CONSERVATION TILLAGE AND PESTICIDE USE IN THE CORNBELT
Adoption of conservation tillage can lead to substantial environmental benefits from reduced soil erosion. But benefits may be partially offset if adoption increases reliance on agricultural chemicals. Using area study data from the Cornbelt, this study examines factors affecting adoption of no-till and other conservation tillage systems and their effect on chemical use and corn yield. The results find no evidence that herbicide or fertilizer application rates are higher on fields with conservation tillage systems compared with conventional tillage. However, insecticide use may increase somewhat and yield may be lower. Current demographic trends in U.S. agriculture favor continued diffusion of conservation tillage.conservation tillage, multinomial logit model, pesticides, technology adoption, Crop Production/Industries,
The Species Richness of Lepidoptera in a Fragmented Landscape: A Supplement to the Checklist of Moths of Butler County, Ohio
Land conversion for agriculture or urban expansion has fragmented the midwestern landscape and isolated native biotas in remnant habitat patches. Identification of priority renmants to be targeted for conservation, however, requires an understanding of the species diversity and distributions in such fragmented landscapes. During a 3-year inventory, we estimated the species richness of Lepidoptera in forests and old fields within an agricultural region of southwest Ohio, Butler County. A combination of casual collecting (butterflies) and a systematic field study (moths) were used to sample lepidopteran species at several sites from 1998-2000. Our inventory added 207 new species to the checklist of the Lepidoptera of Butler County, bringing the total described species richness of the region to 599 species (including Peoria tetradella (Pyralidae), a state record). The species accumulation curve produced from our 1999 moth inventory did not reach saturation, suggesting that additional species remain to be recorded. These results indicate that even highly modified landscapes can support a substantial species diversity of Lepidoptera if there are sufficient areas of native habitat. Since short-term insect inventories tend to be biased toward common, well-known species, rapid diversity assessments may miss important elements of conservation interest. Checklists should remain an important data source for species occurrences and biogeography. Without a well-established knowledge of species geography, critical areas of conservation interest may be overlooked or left unprotected
POLITICAL ECONOMY OF RIGHT-TO-FARM
This paper investigates the motivations for local right-to-farm protection ordinances by estimating a logit model relating the adoption of these ordinances to various political, economic and demographic factors previously found to affect the likelihood of passage of farmland preservation policies. Results suggest that the probability of adopting right-to-farm policies increases with the size and political clout of the farm public and with incentives to promote right-to-farm. Adoption is not enhanced by environmental concerns, nor by factors known to encourage adoption of farmland preservation policies. These findings raise serious concerns about the long-run viability of protections afforded agriculture in urbanizing areas.nuisance litigation, open space, political economy, restrictive ordinances, right-to-farm, Political Economy,
Observations of Early Optical Afterglows
The Swift Ultra-Violet/Optical Telescope (UVOT) has performed extensive
follow-up on 71 Swift Burst Alert Telescope triggered gamma-ray bursts (GRBs)
in its first ten months of operations. In this paper, we discuss some of the UV
and optical properties of UVOT detected afterglows such as XRF 050406, the
bright GRB 050525A, the high redshift GRB 050730, the early flaring GRB 050801,
and others. We also discuss some of the implications of why 75% of GRB
afterglows observed by UVOT in less than one hour are "dark."Comment: 10 pages, 6 figures, to appear in the Proceedings of the 16th Annual
Astrophysics Conference in Maryland "Gamma Ray Bursts in the Swift Era,"
Washington, DC, November 29 - December 2, 200
ACTUARIAL EFFECTS OF UNIT STRUCTURE IN THE U.S. ACTUAL PRODUCTION HISTORY CROP INSURANCE PROGRAM
This paper examines the effects of optional subdivision on APHP losses for wheat, corn, and soybeans. Thirty-seven state/crop programs are analyzed and the implications of the results are discussed in relation to newly developed crop and revenue insurance programs. The results illustrate the importance of incorporating actuarial experience into the premium rate structure and contract provisions of an insurance program.Actual Production History Program (APHP), crop insurance programs, Risk and Uncertainty,
THE PERFORMANCE OF BIOLOGICAL NITROGEN FIXATION TECHNOLOGY IN THE TROPICS: EVIDENCE FROM NORTHEAST THAILAND
Crop Production/Industries,
The Economics of Manure Utilization: Model and Application
A model of manure utilization is developed and applied to four types of transportable manure. Model results highlight important response differences among manure types and generally illustrate the diseconomies of manure production. For example, as manure production increases, manure value decreases and excess phosphate applications increase, thereby increasing the potential for phosphorus runoff. Policy scenarios limiting the manure application rate reduce manure value and excess phosphate application. Increasing the ratio of land using manure increases manure value while reducing excess phosphate application. Buildup of soil nutrients reduces manure value, but either increases or decreases excess phosphate application depending on the scenario.linear programming, manure application, manure transportation, manure utilization, manure value, optimization, Farm Management,
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