Ultraviolet hydrogen-discharge lamp

Device provides stable flux output for calibration of ultraviolet spectrum

A near-earth optical communications terminal with a corevolving planetary sun shield

The umbra of a planet may serve as a sun shield for a space based optical communications terminal or for a space based astronomical observatory. An orbit that keeps the terminal or observatory within the umbra is desirable. There is a corevolution point behind every planet. A small body stabilized at the planet corevolution point will revolve about the sun at the same angular velocity as the planet, always keeping the planet between itself and the sun. This corevolution point is within the umbra of Mars but beyond the end of the umbra for Mercury, Venus, and earth. The Mars corevolution point is an ideal location for an astronomical observatory. There Mars obstruct less than 0.00024 percent of the sky at any time, and it shades the observatory completely from the sun. At the earth corevolution point, between 51 and 84 percent of the solar disk area is blocked, as is up to 92 percent of the sunlight. This provides a reduction from 3 dB to 11 dB in sunlight that could interfere with optical communications if scattered directly into the detectors. The variations is caused by revolution of the earth about the earth-moon barycenter

Fraunhofer filters to reduce solar background for optical communications

A wavelength that lies within a spectral interval of reduced solar emission (a Fraunhofer line) can carry optical communications with reduced interference from direct or reflected background sunlight. Suitable Fraunhofer lines are located within the tuning range of good candidate lasers. The laser should be tunable dynamically to track Doppler shifts in the sunlight incident on any solar system body that may appear in the background as viewed by the receiver. A Fraunhofer filter used with a direct-detection receiver should be tuned to match the Doppler shifts of the source and background. The required tuning calculated here for various situations is also required if, instead, one uses a heterodyne receiver with limited post-detection bandwidth

On the Distribution of Values and Zeros of Polynomial Systems over Arbitrary Sets

Let G_1,..., G_n \in \Fp[X_1,...,X_m] be $n$ polynomials in $m$ variables over the finite field \Fp of $p$ elements. A result of {\'E}. Fouvry and N. M. Katz shows that under some natural condition, for any fixed $\varepsilon$ and sufficiently large prime $p$ the vectors of fractional parts (\{\frac{G_1(\vec{x})}{p}},...,\{\frac{G_n(\vec{x})}{p}}), \qquad \vec{x} \in \Gamma, are uniformly distributed in the unit cube $[0,1]^n$ for any cube $\Gamma \in [0, p-1]^m$ with the side length $h \ge p^{1/2} (\log p)^{1 + \varepsilon}$. Here we use this result to show the above vectors remain uniformly distributed, when $\vec{x}$ runs through a rather general set. We also obtain new results about the distribution of solutions to system of polynomial congruences

Intraoperative Extracorporeal Irradiation for the Treatment of the Meningioma-Infiltrated Calvarium.

Objectives Complete removal of infiltrated bone is required to achieve a Simpson Grade 1 meningioma resection. Reconstruction of the resulting bone defect is typically achieved with a nonnative implant that can result in poor cosmesis, foreign body reaction, or infection. Extracorporeal irradiation and reimplantation of tumorous bone has been used for limb-sparing surgery with excellent results, but this treatment option is not routinely considered in meningioma surgery. We present a case of anterior fossa meningioma with tumorous overlying calvarium that was successfully managed with intraoperative extracorporeal irradiation and reimplantation. Design, Setting, and Participant A 37-year-old woman with persistent chronic headaches was found to have an anterior skull base meningioma with extension into the forehead frontal bone. Concurrently with mass resection, the bone flap was irradiated intraoperatively with 120 Gy. After resection of the tumor, the bone flap was replaced in its native position. Main Outcome Measures and Results Twenty-nine months postoperatively, the patient had an excellent cosmetic outcome with no radiographic evidence of tumor recurrence or significant bone flap resorption. Conclusion Intraoperative extracorporeal irradiation of tumorous calvaria during meningioma surgery is an effective, logistically feasible treatment option to achieve local tumor control and excellent cosmetic outcome

Local form interference in biological motion perception

Peer reviewedPublisher PD

A high-gain omnidirectional satellite antenna technique Final report

High gain omnidirectional satellite system design, using planar and circular multiple beam arrays and solid state switchin