High-temperature, gas-filled ceramic rectifiers, thyratrons, and voltage-reference tubes

Thyratron, capable of being operated as a rectifier and a voltage-reference tube, was constructed and tested for 1000 hours at temperatures to 800 degrees C. With current levels at 15 amps and peak voltages of 2000 volts and frequencies at 6000 cps, tube efficiency was greater than 97 percent

High-temperature, gas-filled, ceramic rectifiers, thyratrons, and voltage- reference tubes Quarterly progress report no. 3, 15 Jun. - 14 Sep. 1965

High temperature, gas filled ceramic rectifiers, thyratrons, and voltage-reference tube

High-temperature, long-life thyratron

Thallium and xenon filled thyratron was developed that operates at tube envelope temperatures up to 750 C. This tube performs at peak voltage ratings of 2000 V forward and reverse and at an average current rating of 15 A for up to 11,000 hours

Development of high-temperature, gas-filled, ceramic rectifiers, thyratrons, and voltage-reference tubes Final report, Dec. 15, 1964 - Jan. 26, 1966

Development of high temperature gas filled ceramic rectifiers, thyratrons, and voltage-regulator tube

Ect2/Pbl Acts via Rho and Polarity Proteins to Direct the Assembly of an Isotropic Actomyosin Cortex upon Mitotic Entry.

Entry into mitosis is accompanied by profound changes in cortical actomyosin organization. Here, we delineate a pathway downstream of the RhoGEF Pbl/Ect2 that directs this process in a model epithelium. Our data suggest that the release of Pbl/Ect2 from the nucleus at mitotic entry drives Rho-dependent activation of Myosin-II and, in parallel, induces a switch from Arp2/3 to Diaphanous-mediated cortical actin nucleation that depends on Cdc42, aPKC, and Par6. At the same time, the mitotic relocalization of these apical protein complexes to more lateral cell surfaces enables Cdc42/aPKC/Par6 to take on a mitosis-specific function-aiding the assembly of a relatively isotropic metaphase cortex. Together, these data reveal how the repolarization and remodeling of the actomyosin cortex are coordinated upon entry into mitosis to provide cells with the isotropic and rigid form they need to undergo faithful chromosome segregation and division in a crowded tissue environment

The Consistent Newtonian Limit of Einstein's Gravity with a Cosmological Constant

We derive the `exact' Newtonian limit of general relativity with a positive cosmological constant $\Lambda$. We point out that in contrast to the case with $\Lambda = 0$, the presence of a positive $\Lambda$ in Einsteins's equations enforces, via the condition $| \Phi | \ll 1$, on the potential $\Phi$, a range ${\cal R}_{max}(\Lambda) \gg r \gg {\cal R}_{min} (\Lambda)$, within which the Newtonian limit is valid. It also leads to the existence of a maximum mass, ${\cal M}_{max}(\Lambda)$. As a consequence we cannot put the boundary condition for the solution of the Poisson equation at infinity. A boundary condition suitably chosen now at a finite range will then get reflected in the solution of $\Phi$ provided the mass distribution is not spherically symmetric.Comment: Latex, 15 pages, no figures, errors correcte

Development of high temperature ceramic rectifiers, thyratrons, and voltage regulator tubes final report, jun. 26, 1963 - oct. 7, 1964

Ceramic voltage regulator tubes, gas diodes, and thyratron

Development of high-temperature, gas-filled, ceramic rectifiers, thyratrons, and voltage- reference tubes quarterly progress report no. 2, 15 mar. - 14 jun. 1965

High temperature ceramic thyratron tube researc

Development of high-temperature, gas-filled, ceramic rectifiers, thyratrons, and voltage- reference tubes quarterly progress report no. 1, dec. 15, 1964 - mar. 14, 1965

High temperature ceramic rectifier, thyratrons, and voltage reference tubes for use in nuclear- electric space power system

Asteroid observations and planetary atmospheres analysis

Photoelectric observations of Eros and 30 other asteroids providing information on their surface characteristics, shape, and rotation axes are reported. Photographs of 18 asteroids and 4 comets yielding accurate position information on various dates were obtained. Photometric observations were made of the Saturn satellite lapetus, and electronographic images of the Uranus and Neptune satellites were obtained experimentally with a Spectracon tube to assess photometry by that method. Planetary patrol photographs of Venus and deconvolved area scans of Uranus were taken. UBV photometry of the Galilean satellites for the period 1973-1974 was completely analyzed and accepted for publication. An improved magnitude and color index for Minas were derived from 1974 area scans. A special photomultiplier tube with a suppressor grid was incorporated into a pulse-counting photometer with special added circuitry for carrying out the observations concerning the constancy of solar system dimensions over cosmic time