5,449 research outputs found
FARMER TRUST IN AGRICULTURAL COOPERATIVES: EVIDENCE FROM MISSOURI CORN AND SOYBEAN PRODUCERS
We examine whether cooperatives are characterized by greater trust than investor-owned firms. We survey 2000 Missouri corn and soybean farmers and find that trust and farmer perceptions of trustworthiness and competence are higher in cooperatives than in investor-owned firms and that trust is a significant factor explaining the choice of farmers to market to cooperatives rather than investor-owned firms. Interestingly, we find that trust is more significant in producers' decisions for marketing soybeans than for corn.Agribusiness,
Idea Early Intervening Services Policy Implementation in Six School Districts;Reducing Overidentification and Disproportionality
The Individual with Disability Educational Improvement Act (IDEA-2004) (P.L. 108-446) includes a policy called Early Intervening Services (EIS) which makes it permissible, but not mandatory, for a school district to use 15 percent of their IDEA Part B funds to provide services to non-disabled at risk students. However, a school district cited for disproportionality because of an overrepresentation of racial or ethnic minorities or second language learners receiving special education services or disciplinary action is required to use 15 percent of their special education funding to address these issues. The purpose of this study was to obtain knowledge on the impact of this IDEA policy at the local public school district level on the overidentification of students in general and specifically on the overrepresentation of African Americans in special education services. The design of the study utilized parallel case studies in six Northeast Ohio school districts. Three of these districts were cited for disproportionality and three districts were not cited for disproportionality. The design relied on two interviews in each district. Additional data was obtained from reviews of federal, state and school district records and relevant secondary sources. Four policy themes emerged from the Study: EIS policy was confusing because it lacked clarity on how disproportionality was determined funding was punitive because it reduced funds for students with disabilities to provide interventions for general education vi students implementation was unfair because some districts were required to establish EIS services and some were not and the additional workload created for administrators was excessive. The three districts that used EIS funding to address a disproportionate number of African American students assigned to special education categories showed a reduction in disproportionality and were not cited after a year of EIS. However, the cause of this success was questioned because the benchmark for determining disproport
Farmer Trust in Producer- and Investor-owned Firms: Evidence from Missouri Corn and Soybean Producers
The definitive version is available at www3.interscience.wiley.com.We examine whether cooperatives are characterized by greater trust than investor-owned firms. We survey 2000 Missouri corn and soybean farmers and find that trust and farmer perceptions of honesty and competence are higher in cooperatives than in investor-owned firms and that trust is a significant factor explaining the choice of farmers to market to cooperatives rather than investor-owned firms. Interestingly, we find that trust is more significant in producers' decisions for marketing soybeans than for corn
Development of primary invasive pneumococcal disease caused by serotype 1 pneumococci is driven by early increased type I interferon response in the lung
The pneumococcus is the world's foremost respiratory pathogen, but the mechanisms allowing this pathogen to proceed from initial asymptomatic colonization to invasive disease are poorly understood. We have examined the early stages of invasive pneumococcal disease (IPD) by comparing host transcriptional responses to an invasive strain and a noninvasive strain of serotype 1 Streptococcus pneumoniae in the mouse lung. While the two strains were present in equal numbers in the lung 6 h after intranasal challenge, only the invasive strain (strain 1861) had invaded the pleural cavity at that time point; this correlated with subsequent development of bacteremia in mice challenged with strain 1861 but not the noninvasive strain (strain 1). Progression beyond the lung was associated with stronger induction of the type I interferon (IFN-I) response in the lung at 6 h. Suppression of the IFN-I response through administration of neutralizing antibody to IFNAR1 (the receptor for type I interferons) led to significantly reduced invasion of the pleural cavity by strain 1861 at 6 h postchallenge. Our data suggest that strong induction of the IFN-I response is a key factor in early progression of invasive serotype 1 strain 1861 beyond the lung during development of IPD
Markets, Contracts, or Integration? The Adoption, Diffusion, and Evolution of Organizational Form
The rise of contract farming and vertical integration is one of the most important changes in modern agriculture. Yet the adoption and diffusion of these new forms of organization has varied widely across regions, commodities, or farm types, however. Transaction cost theories and the like are not fully effective at explaining the variation of adoption rates of different organizational forms, in part because of their inherent static nature. In order to explain the adoption, diffusion and evolution of organizational form, a more dynamic framework is required. This paper lays out such a framework for understanding the evolution of organizational practices in U.S. agriculture by drawing on existing theories of economic organization, the diffusion of technological innovation, and organizational complementarities. Using recent trends as stylized facts we argue that the agrifood sector is characterized by strong complementarities among its constituent features and that these complementarities help explain the stylized facts. We also discuss several testable hypotheses concerning changes in organizational form in agriculture.contracting, vertical integration, organizational innovation, diffusion, Institutional and Behavioral Economics, L14, L22, Q13, O33,
Systems engineering analysis of aplanatic Wolter type I x-ray telescopes
It is well known that normal-incidence aplanatic telescope designs perform better at small field angles than ones corrected only for spherical aberration. This is why most large astronomical telescopes fabricated in the past fifty years have been of the Ritchey-Chretien (aplanatic) design rather than of the classical Cassegrain design. For the relatively new field of x-ray astronomy, the Welter type I grazing incidence design has been extensively utilized. It consists of a paraboloidal primary mirror coaxial with a confocal hyperboloidal secondary mirror. Aplanatic versions of the Welter type I grazing incidence x-ray telescope have been discussed in detail in the literature, and are widely touted as being superior designs. However, scattering effects from residual optical fabrication errors and other practical engineering error sources prevent these grazing-incidence telescopes from being near diffraction-limited (even on axis) at the very short operational x-ray wavelengths. A systems engineering analysis of these error sources indicates that they will dominate coma at the small field angles, and of course astigmatism, field curvature, and higher-order aberrations dominate coma at the large field angles. Hence, there is little improvement in performance when going to an aplanatic design. Comparison of performance predictions for the classical versus aplanatic Welter type I x-ray telescope are presented for the special case of the Solar X-Ray Imager (SXI) baseline design. SXI is expected to become a standard subsystem aboard the next generation of NOAA/GOES weather satellites
The role of narrow-angle forward surface scatter and particulate scatter in exoplanet exploration
It is often thought that because of the very small solid angle subtended by the field-of-view of the coronagraph, scattered light from optical surfaces will have no effect on images recorded for terrestrial exoplanet spectroscopy. In this paper, we examine mirror surface scatter and particulate contamination scatter as sources of background light or noise signal in large aperture terrestrial exoplanet telescope/coronagraph systems. Scattered light control to one part in 10^(+10) or better is required for exoplanet exploration. We will discuss the optical fabrication tolerances necessary to minimize narrowangle forward scatter and their relative effects upon direct imaging coronagraph instruments used to characterize terrestrial exoplanets
Markets, Contracts, or Integration? The Adoption, Diffusion, and Evolution of Organizational Form
The rise of contract farming and vertical integration is one of the most important changes in modern agriculture. Yet the adoption and diffusion of these new forms of organization has varied widely across regions, commodities, and farm types. Transaction cost and other modern theories of the firm help explain the advantages of contracting and integration over reliance on spot markets and commodity brokers. However, these theories do not address the variation in adoption rates of new organizational forms. This paper lays out a more dynamic framework for understanding the evolution of organizational practices in U.S. agriculture, drawing on theories of the diffusion of technology and organizational complementarities. Using recent trends as stylized facts we argue that the agrifood sector is characterized by strong complementarities and that identifying and describing these complementarities more fully sheds considerable light on the organizational structure of agricultural production. We illustrate our arguments with case studies from the oilseed, poultry, and hog industries
Exoplanet telescope diffracted light minimized: the pinwheel-pupil solution
Terrestrial exoplanets shine in light reflected from a parent star. Optical spectra are required to provide evidence of a life-supporting environment. Exoplanets are very faint and their optical spectra are contaminated by the spectrum of the parent star. High angular resolution provided by large apertures is needed to distinguish between the spectrum of the exoplanet and its star. Today, large aperture telescopes use segmented primary mirrors that employ close-packed hexagonal segments. The telescope primary mirror is periodically discontinuous with straight lines. These discontinuities scatter unwanted radiation from the much brighter parent star across the field of view to obscure the light from the very faint terrestrial exoplanet. These discontinuities, which mimic a diffraction grating, result in a non-uniform distribution of background light across the image plane. This non-uniformity masks or hides exoplanets from view, to reduce the number of exoplanets that can be observed with a large aperture telescope or to reduce the quality of spectra and thus lead to misinterpretation of data. Here we introduce the concept of the pinwheel pupil whose unique diffraction pattern significantly reduces the non-uniform distribution of background radiation. Diffraction patterns from pinwheel pupils are compared to the monolithic filled aperture, the classical Cassegrain, the 60-degree symmetry of the hexagonal segments (JWST, E-ELT, etc.). Diffraction “spikes” are reduced by at least 105. We discuss the “pinwheel pupil” advantages to spectroscopy, image processing, and observatory operations. We show that, segment fabrication of curved-sided mirrors is not more difficult than fabrication of hexagonal mirror segments. . This is the report of quantitative study of Fraunhofer (far field) diffraction patterns produced by three different topologies or architectures of mirror segmentation, when illuminated by a plane wave of monochromatic white-light. A plot, in angular units of the intensity as a function of azimuth, Phi_f , within annular rings at different FOVs, centered on the system axis of the diffraction pattern will be presented. The advantages of the segmented pinwheel pupil is discussed
Balancing detector effects with aberrations in the design of wide-field grazing incidence x-ray telescopes
Most imaging systems today include a mosaic detector array in the focal plane. Optical designers of astronomical telescopes typically produce a design that yields a superb on-axis aerial image in the focal plane, and detector effects are included only in the analysis of the final system performance. Aplanatic optical designs (corrected for spherical aberration and coma) are widely considered to be superior to nonaplanatic designs. However, there is little merit in an aplanatic design for wide-field applications because one needs to optimize some field-weighted-average measure of resolution over the desired operational field of view (OFOV). Furthermore, when used with a mosaic detector array in the focal plane, detector effects eliminate the advantage of the aplanatic design even at small field angles. For wide fields of view, the focal plane is frequently despaced to balance field curvature with defocus thus obtaining better overall performance. We will demonstrate that including detector effects in the optical design process results in a different optimal (nonaplanatic) design for each OFOV that is even superior to an optimally despaced aplanatic design
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