Some elementary observations regarding reductive Cartan geometries

After defining generalizations of the notions of covariant derivatives and geodesics from Riemannian geometry for reductive Cartan geometries in general, various results for reductive Cartan geometries analogous to important elementary results from Riemannian geometry are proven using these generalizations. In particular, a generalization of the Hopf-Rinow theorem is given with a pleasantly concise proof.Comment: 8 pages, no figure

Observations of an increase in the flux from Tau A during occultation by the solar corona

Flux increase from Tau A during solar corona occultatio

[Studies in the 11 Meter Range of Radio Astronomy Using High Resolution and High Sensitivity Antenna Arrays at Clark Lake]

Interplanetary scintillation observations from solar wind inhomogeneitie

Solar emission levels at low radio frequencies

Solar radio emission could seriously interfere with observations made by a low frequency (1 to 10 MHz) array in space. International Sun-Earth Explorer (ISEE-3) radio data were used to determine solar emission level. The results indicate that solar emission should seriously disturb less than ten percent of the data, even during the years of solar maximum. Thus it appears that solar emission should not cause a disastrous loss of data. The information needed to design procedures to excise solar interference from the data produced by any low-frequency array is provided

Radio interference in the near-earth environment

Natural and man-made radio frequency interference (RFI) are potentially serious obstacles to the successful operation of an array of spacecraft used for low frequency (1 to 30 MHz) radio interferometry in the near-earth environment. Several satellites and planetary probes have carried radio astronomy experiments, and the moderate data base that they provide are examined to help understand the near-earth RFI environment. The general conclusion is that the region of space within 100 earth-radii of the earth is a hostile environment for any radio astronomy experiment. If a low frequency array in earth orbit is to yield useful astronomical results, severe interference problems must be anticipated and overcome. A number of recommendations are made to further examine the feasibility of such an array

Ablation article and method

An ablation article, such as a conical heat shield, having an ablating surface is provided with at least one discrete area of at least one seed material, such as aluminum. When subjected to ablation conditions, the seed material is ablated. Radiation emanating from the ablated seed material is detected to analyze ablation effects without disturbing the ablation surface. By providing different seed materials having different radiation characteristics, the ablating effects on various areas of the ablating surface can be analyzed under any prevailing ablation conditions. The ablating article can be provided with means for detecting the radiation characteristics of the ablated seed material to provide a self-contained analysis unit

Electron Self Energy for Higher Excited S Levels

A nonperturbative numerical evaluation of the one-photon electron self energy for the 3S and 4S states with charge numbers Z=1 to 5 is described. The numerical results are in agreement with known terms in the expansion of the self energy in powers of Zalpha.Comment: 3 pages, RevTeX, to appear in Phys. Rev.

Degree-Day Summation and Hatching of the Forest Tent Caterpillar, \u3ci\u3eMalacosoma Disstria\u3c/i\u3e (Lepidoptera: Lasiocampidae)

(excerpt) The forest tent caterpillar, Malacosoma disstria (Htibner), is a common defoliater of deciduous trees throughout most of the United States and Canada. It is a well known outbreak species, whose populations erupt periodically (every 10 to 16 years) when forest conditions are suitable. Typical outbreaks last three to six years in a given geographic area and then collapse as quickly as they arise. This note documents the relation between forest tent caterpillar egg hatching in the field and heat accumulation (degree-days) leading up to hatch. This information will permit (a) predicting the date on which eggs will hatch by summing degree days during the insect\u27s overwintering period, and (b) comparing with populations in other years and areas. The data came from an outbreak in northern Minnesota that began near International Falls in 1966 and collapsed in 1972 (Witter et al., 1975)

Rotor systems research aircraft airplane configuration flight-test results

The rotor systems research aircraft (RSRA) has undergone ground and flight tests, primarily as a compound aircraft. The purpose was to train pilots and to check out and develop the design flight envelope. The preparation and flight test of the RSRA in the airplane, or fixed-wind, configuration are reviewed and the test results are discussed

Long wavelength investigations of solar, planetary, and galaxy emissions Final report, May 1 - Sep. 30, 1964

Feasibility of constructing large antenna array and interferometer for radio astronomy studies and spectral observations of discrete sources, sun, and Galax