Development of a Low-Flying CubeSat Mission for F-Region Characterization

Plasma irregularities in the F-region (200-800 km) of the night-time equatorial ionosphere have been shown to significantly influence the performance and reliability of space borne and ground based radio communication systems. Equatorial Spread-F (ESF) episodes may cause the disruption of satellite operations, communications, and navigation due to backscatter and radar scintillation. Current records of rocket, satellite, and radar data are not of sufficient quantity to allow for accurate models and predictions of the spectrum of irregularities. To provide a better understanding and predict F-region phenomena that may disrupt communications, it is important to perform in situ, or local, real-time measurements in areas that these irregularities begin. Typically, satellite orbits at altitudes in the bottomside F region have a very limited lifetime due to atmospheric drag. The objective of the Low-Flyer CubeSat mission is to provide scientific data through improved in situ instruments and methods to better characterize the F-region of the ionosphere. Achieving low altitudes near 200 km while still enduring a mission lifetime that encompasses each season, the Low-Flyer CubeSat mission intends to implement an elliptic orbit through the use of on board propulsion. This presentation will overview the technical details and operation of this unique CubeSat mission

Privatization Methods and Productivity Effects in Romanian Industrial Enterprises

Comprehensive panel data on privatization transactions and labor productivity in Romanian industrial corporations are used to describe the post-privatization ownership structure, and to estimate the effect of Romania\u27s diverse privatization policies on firm performance. The econometric results show consistently positive, highly significant effects of private ownership on labor productivity growth, the point estimates imply- ing an increased 1.0 to 1.7 percentage growth for a 10 percent rise in private shareholding. The strongest estimated impacts are associated with sales to outside blockholders; insider transfers and mass privatization are estimated to have significantly smaller—although still positive—effects on firm performance

Balancing the demands of validity and reliability in practice: case study of a changing system of primary science summative assessment

Teacher summative judgements of children’s attainment in science, which are statutory at age 11 in England, require consideration of both valid sampling of the construct and reliable comparison of outcomes. In order to develop understanding of the enacted ‘trade off’ between validity and reliability, this three-year case study, within the Teacher Assessment in Primary Science (TAPS) project, was undertaken during a period of statutory assessment change in England. The case demonstrates an ongoing balancing act between the demands of reliability and validity, and resulted in the development of a teacher assessment seesaw, which provides a model for both interpreting and supporting practice, within and beyond primary science

First Neutrino Observations from the Sudbury Neutrino Observatory

The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed.Comment: Latex, 7 pages, 10 figures, Invited paper at Neutrino 2000 Conference, Sudbury, Canada, June 16-21, 2000 to be published in the Proceeding

Measurement of the rate of nu_e + d --> p + p + e^- interactions produced by 8B solar neutrinos at the Sudbury Neutrino Observatory

Solar neutrinos from the decay of $^8$B have been detected at the Sudbury Neutrino Observatory (SNO) via the charged current (CC) reaction on deuterium and by the elastic scattering (ES) of electrons. The CC reaction is sensitive exclusively to nu_e's, while the ES reaction also has a small sensitivity to nu_mu's and nu_tau's. The flux of nu_e's from ^8B decay measured by the CC reaction rate is \phi^CC(nu_e) = 1.75 +/- 0.07 (stat)+0.12/-0.11 (sys.) +/- 0.05(theor) x 10^6 /cm^2 s. Assuming no flavor transformation, the flux inferred from the ES reaction rate is \phi^ES(nu_x) = 2.39+/-0.34 (stat.)+0.16}/-0.14 (sys) x 10^6 /cm^2 s. Comparison of \phi^CC(nu_e) to the Super-Kamiokande Collaboration's precision value of \phi^ES(\nu_x) yields a 3.3 sigma difference, providing evidence that there is a non-electron flavor active neutrino component in the solar flux. The total flux of active ^8B neutrinos is thus determined to be 5.44 +/-0.99 x 10^6/cm^2 s, in close agreement with the predictions of solar models.Comment: 6 pages (LaTex), 3 figures, submitted to Phys. Rev. Letter

From the Caribbean to Craignish : imperial authority and piratical voyages in the early eighteenth-century Atlantic commons

Whereas seventeenth-century piracy has been recognised as an integrated component of the developing European Atlantic world, eighteenth-century pirates have been marginalised as an isolated group with few ties to landed communities. Such evaluations have stressed the heightened extension of state authority to the colonial theatre in the eighteenth century and, by doing so, have overlooked how pirates continued to interact with colonial actors operating in contested and unclaimed regions throughout the Atlantic commons. It is imperative that the Atlantic commons is given full consideration in any discussion of Atlantic maritime activity as it was within these expanses that inter-imperial, inter-colonial, and cross-border colonial actors converged. This article utilises the piratical voyage captained by Howell Davies (and later Bartholomew Roberts) to demonstrate that it was within this commons that eighteenth-century piratical voyages were sustained and facilitated through the forced acquisition of supplies, through markets for plundered goods, and through the opportunities available for dispersing amongst landed communities at the end of expeditions. Continued connections between colonial denizens and pirates in the eighteenth century compels a reassessment of pirates’ isolation to instead place them within the wider population of coastal traders, sojourning mariners, and marginal colonial settlers who existed both within and outside of the imperial framework espoused by state and colonial centres. Ultimately, this questions the overall ability of European states to regulate maritime traffic when vessels sailed out of sight of established colonial ports, and beyond the practical reach of imperial authority

The D0 Run II Impact Parameter Trigger

Many physics topics to be studied by the D0 experiment during Run II of the Fermilab Tevatron ppbar collider give rise to final states containing b--flavored particles. Examples include Higgs searches, top quark production and decay studies, and full reconstruction of B decays. The sensitivity to such modes has been significantly enhanced by the installation of a silicon based vertex detector as part of the DO detector upgrade for Run II. Interesting events must be identified initially in 100-200 microseconds to be available for later study. This paper describes custom electronics used in the DO trigger system to provide the real--time identification of events having tracks consistent with the decay of b--flavored particles.Comment: To be submitted to Nucl. Instrum. Methods A. 56 pages, 31 figure