Polarimetry with a soft x-ray spectrometer

An approach for measuring linear X-ray polarization over a broad-band using conventional spectroscopic optics is described. A set of multilayer-coated flats reflect the dispersed X-rays to the instrument detectors. The intensity variation as a function of energy and position angle is measured to determine three Stokes parameters: I, Q, and U. By laterally grading the multilayer optics and matching the dispersion of the gratings, one may take advantage of high multilayer reflectivities and achieve modulation factors over 80% over the entire 0.2 to 0.8 keV band. A sample design is shown that could be used with a small orbiting mission.Comment: Accepted for publication in the proceedings of the SPIE, volume 701

CHAPTER 10: UPPER-MIDDLE-CLASS POLITICS AND POLICY OUTCOMES: DOES CLASS IDENTITY MATTER?

This chapter in Clark and lipset\u27s book on class in American politics resulted from a multi-day workshop at the Woodrow Wilson Center for International Scholars in the summer of 1999. The piece reverses the normal causality of class politics. It does not analyze citizens in elections, but government officials creating policies. It asks why policies differ across localities (specifically public transit decisions in 42 U.S. metropolitan areas). It probes how some government officials work with an upper-middle-class citizenry in mind, while others do so less. The chapter then tests for differences across localities and finds quite distinct patterns. The chapter next elaborates specific contours of the American upper middle class, in a creative merging of themes from Thorsein Veblen and David Riesman to current work on public policy

Updating the Chandra HETGS Efficiencies using In-Orbit Observations

The efficiencies of the gratings in the High Energy Transmission Grating Spectrometer (HETGS) were updated using in-flight observations of bright continuum sources. The procedure first involved verifying that fluxes obtained from the +1 and -1 orders match, which checks that the contaminant model and the CCD quantum efficiencies agree. Then the fluxes derived using the high energy gratings (HEGs) were compared to those derived from the medium energy gratings (MEGs). The flux ratio was fit to a low order polynomial, which was allocated to the MEGs above 1 keV or the HEGs below 1 keV. The resultant efficiencies were tested by examining fits to blazar spectra.Comment: 10 pages, 7 figures; to appear in the SPIE proceedings, volume 844

A Soft X-ray Polarimeter Designed for Broad-band X-ray Telescopes

A novel approach for measuring linear X-ray polarization over a broad-band using conventional imaging optics and cameras is described. A new type of high efficiency grating, called the critical angle transmission grating is used to disperse soft X-rays radially from the telescope axis. A set of multilayer-coated paraboloids re-image the dispersed X-rays to rings in the focal plane. The intensity variation around these rings is measured to determine three Stokes parameters: I, Q, and U. By laterally grading the multilayer optics and matching the dispersion of the gratings, one may take advantage of high multilayer reflectivities and achieve modulation factors over 50% over the entire 0.2 to 0.8 keV band. A sample design is shown that could be used with the Constellation-X optics.Comment: 11 pages, 7 figures, presented at conference 6688 of the SPI

Noise figure considerations in the design of superhetrodyne receiver input circuits.

Thesis (M.A.)--Boston Universit

Trend Spotting: NAFTA Disputes After Fifteen Years

Cross-border investment disputes have supplanted trade disputes as the main focus of legal actions under the North American Free Trade Agreement (NAFTA), according to this study. The author finds a growing number of these investment disputes entail challenges by American investors against Canada's provincial, as opposed to federal, laws and regulations. So important constitutional issues need clarifying between Ottawa and the provinces. He notes as party to the treaty, Ottawa must carry the ball in court but who is really responsible? Who pays when the provinces or municipalities run afoul of Ottawa’s multilateral commitments?International Policy, NAFTA, trade remedy disputes, Canadian federal government, Canadian provincial governments

American Corn and Canadian Trade Actions: One Step Forward, Two Steps Back

On January 8 this year, the Canadian government initiated what will be one of Canada’s largest trade disputes against the United States, by challenging US Farm Bill subsidies for corn, soy and other grain products at the World Trade Organization (WTO). This case is the first of its kind launched by Canada, not only attacking existing Farm Bill programs but implicitly challenging any revitalized subsidy programs that might appear in Farm Bill replacement legislation currently before Congress.international policy, Canadian trade policy

Rapid billet loader aids extrusion of refractory metals

A combination gravity and manually powered rapid billet loader reduces the time required for transferring hot metal billets from a heating furnace to an extrusion press. Positioned between the furnace and extrusion press, this loader is a simple slide-delivery device