Coherently pulsed laser source

An electronically controllable apparatus is described which modulates a continuous wave laser beam so as to produce an output beam consisting of coherent pulses that are electronically controllable as to both pulse repetition rate and pulse width. The apparatus includes two acoustic devices positioned so that the laser beam passes through them in sequence, and apparatus for passing sound waves through the devices to frequency shift the laser radiation as well as to diffract it. Each acoustic device generates sound waves containing a group of frequencies which result in spaced pulses. The first acoustic device is countered by the second acoustic device to produce a collimated, coherently pulsed, laser beam

Correlation spectrometer having high resolution and multiplexing capability

A correlation spectrometer permanently incorporates a reference cell and an electro-optical phase modulator (EOPM) in the light path between a sample cell and a detector. The effect of the EOPM is such that its frequency modulates all of the monochromatic component of the incoherent radiation passing through it. The EOPM is adjusted so that when it is ON all of the energy in the monochromatic components is thrown into sidebands differing from the original frequencies by integral multiples of the modulation frequency with the total amount of energy absorbed from the original radiation remaining constant. When there is no coincidence between the constituents in the two cells, the detector's output is the same when the EOPM is ON and when it is OFF. However, when there is coincidence the detector's output changes when the EOPM is switched between its two states. The change in the detector's output is related to the quantity of the constituents in the sample cell

Israel in Bureaus of Jewish Education

A report on the track record of bureaus in Israel education, and recommendations for partnerships with other community organizations to allow BJEs to be successful in intensifying, disseminating, and improving Israel education throughout North America

Perturbative QCD Corrections to the Soft Pomeron

We study the interface between soft and hard QCD at high energy and small momentum transfer. At LHC and SSC energies, we find that a cutoff BFKL equation leads one to expect a measurable perturbative component in traditionally soft processes. We show that the total cross section could become as large as 175 mb (122 mb) and the rho parameter 0.40 (0.25) at the SSC (LHC).Comment: 10 pages, McGill/92--2

Stark cell optoacoustic detection of constituent gases in sample

An optoacoustic detector for gas analysis is implemented with Stark effect cell modulation for switching a beam in and out of coincidence with a spectral line of a constituent gas in order to eliminate the heating effect of laser energy in the cell as a source of background noise. By using a multiline laser, and linearly sweeping the DC bias voltage while exciting the cell with a multiline laser, it is possible to obtain a spectrum from which to determine the combinations of excited constituents and determine their concentrations in parts per million

SEVENTEEN FAMOUS ECONOMISTS WEIGH IN ON COPYRIGHT: THE ROLE OF THEORY, EMPIRICS, AND NETWORK EFFECTS

In 2002, seventeen economists including five Nobel Laureates presented an amicus curiae brief discussing the economics of copyright extension in support of the petitioners in Eldred v. Ashcroft. The economists’ amicus brief was unusual in several respects, not least in that it brought together a group of economists almost as notable for its diversity of opinion (spanning the ideological spectrum from Kenneth Arrow to Milton Friedman) as for its academic distinction. When such a distinguished and broad panel of economists readers would have every reason to believe that the arguments set forth in this document are sound down to the smallest details. Yet this is not the case. Scholars in the fields of law and economics will continue to address the economics of copyright duration in the foreseeable future, so it is important that they understand the imperfections in the economists’ brief. This Article provides a counterweight to the amicus brief, identifying some points the economists ignored, clarifying some discussions they did not quite get right, and providing data that runs counter to some assumptions they made.Eldred, coypright, sonny bono, lessig

Sources of the ultraheavy cosmic rays

The suggestions that the source abundances of cosmic ray nuclei heavier then Fe differ significantly from Solar System abundances are not well supported by the data without assuming preferential acceleration. The Solar System abundances of Pb and Bi are split into r-, standard s-, and cyclic 8-process components; the apprarent deficiency of Pb seen in the HEAO-3 Heavy Nuclei Experiment data might indicate an absence of Pb from the recycling 8-process

Hypothetical-Actual Bid Calibration of a Multi-Good Auction

Evidence suggests the calibration of hypothetical and actual behavior is good-specific. We examine whether clustering commodities into mutual categories can reduce the burden. While we reject a common calibration across sets of commodities, a sport-specific calibration function cannot be rejected.Valuation, Calibration, Clusters

A Randomized Trial and the Treatment of Pemphigus Vulgaris

Pemphigus vulgaris is a rare, life-threatening autoimmune disease. Mycophenolate mofetil is a potent immunosuppressant medication approved by the Food and Drug Administration to be used after solid organ transplantation and to treat pemphigus vulgaris. Mycophenolate mofetil has not become the “wonder drug” that had been anticipated based on initial clinical reports. Studies like that reported by Beissert et al. in this issue are essential to improve dermatologic care

Curve fits of predicted inviscid stagnation-point radiative heating rates, cooling factors, and shock standoff distances for hyperbolic earth entry

Curve-fit formulas are presented for the stagnation-point radiative heating rate, cooling factor, and shock standoff distance for inviscid flow over blunt bodies at conditions corresponding to high-speed earth entry. The data which were curve fitted were calculated by using a technique which utilizes a one-strip integral method and a detailed nongray radiation model to generate a radiatively coupled flow-field solution for air in chemical and local thermodynamic equilibrium. The range of free-stream parameters considered were altitudes from about 55 to 70 km and velocities from about 11 to 16 km.sec. Spherical bodies with nose radii from 30 to 450 cm and elliptical bodies with major-to-minor axis ratios of 2, 4, and 6 were treated. Powerlaw formulas are proposed and a least-squares logarithmic fit is used to evaluate the constants. It is shown that the data can be described in this manner with an average deviation of about 3 percent (or less) and a maximum deviation of about 10 percent (or less). The curve-fit formulas provide an effective and economic means for making preliminary design studies for situations involving high-speed earth entry