Alternative Approach to Sequence-Specific Recognition of DNA: Cooperative Stacking of Dication Dimers─Sensitivity to Compound Curvature, Aromatic Structure, and DNA Sequence
Not provided.
Biochemistry & Molecular Biology↗
Engineering topics
Terrell, J.
Publications and source records attributed to Terrell, J..
DMSP satellite detections of gamma-ray bursts
Gamma-ray burst detectors are aboard six U. S. Air Force defense Meteorological Satellite Program (DMSP) spacecraft, two of which are currently in use. Their 800-km altitude orbits give a field of view to 117 degrees from the zenith. A great many bursts have been detected, usually in coincidence with detections by GRO or other satellites such as PVO or ULYSSES. The directions of the sources can be determined with considerable accuracy from such correlated observations, even when GRO/BATSE with its directional capabilities is not involved. Thus these DMSP data, especially in conjunction with other observations, should be helpful in trying to understand the true nature of gamma-ray bursts.
Terrell, J.↗
Evidence for an about 300 day period in Cygnus X-1
Results from 10 years of observation of Cyg X-1 by the Vela 5B satellite are reported. Good evidence for an approximately 300 day period is found, which is confirmed by independent data from the All-Sky Monitor instrument on Ariel 5. Cyg X-1 varies by about 25 percent with a 294 + or -4 day period. This modulation is apparently unrelated to the known transitions between the source high and low states. Flux minima occur at 1974.05+nP. The 294 day period is consistent with the precession of the supergiant companion HDE 226868 and also with the precession period of a tilted accretion disk. The light curve could be modulated by a change in the mass transfer rate or variable obscuration by ionized matter.
Priedhorsky, W. C.↗
Observation of two gamma-ray bursts by Vela X-ray detectors
Bursts of X-rays coincident in time with two gamma-ray burst events were observed by the 3-12 keV collimated X-ray detectors on the Vela spacecraft. Both of these observations show recurrence on a time scale of hundreds of seconds. For one of these events (GB 720514) the X-ray detection gives an improved position as well as information on the spectrum late in the outburst. The other event (GB 740723) is of special interest because the source, not previously located, is consistent in direction with the binary pulsar SMC X-1 in the Small Magellanic Cloud; this is the first moderately small error box for a gamma-ray burst to contain a strong X-ray source.
Terrell, J.↗
Gamma-ray burst systematics
A systematic classification of gamma-ray bursts is considered on the basis of temporal and spectral burst features. Three categories of bursts are proposed, and the category of classical (or normal) bursts is subdivided into three classes: very brief, doublet/quasi-periodic, and long irregular. Apparent correlations are discussed between emission lines and the doublet/quasi-periodic class and between absorption lines and the long irregular class.
Klebesadel, R. W.↗
Spectral evolution of the 5 March 1979 gamma burst
The spectral development of the intense gamma-ray burst observed on March 5, 1979 by nine spacecraft spaced on an interplanetary scale is discussed. As observed by the Pioneer Venus Orbiter detector, the hardness ratio of the burst, defined as the ratio between counts in the 100-1000 keV channels to those in the 50-100 keV channel, decreases during the very fast rise and subsequent 75 msec of the burst, consistent with a decrease in black-body temperature from 30 to 26 keV, and then increases during the shoulder on the gamma-ray burst light curve. Following the burst, the source was observed to exhibit many of the characteristics of a hard X-ray pulsar with a period of 8.0 sec and a hardness ratio varying in phase with the intensity. The observed characteristics of the pulsations are interpreted in terms of hot spots at the magnetic poles of a rotating neutron star, although it is shown that the simple cooling of residual hot spots does not completely explain the pulsations. Alternative explanations for the pulsation include accretion or an effect of beam geometry.
Fenimore, E. E.↗
Gamma-ray burst observations from the UCB/LASL experiment of ISEE-3
The University of California at Berkeley (UCB)/Los Alamos Scientific Laboratory (LASL) gamma-ray burst experiment on board ISEE-3 is described and initial results of the experiment are presented. The instrument consists of an X-ray spectrometer originally designed to monitor solar emission continuously over the energy range 4.8-1264 keV with additional electronics to record data from the intense, short-lived gamma ray bursts at a very high rate and with good timing accuracy. Since the launch of ISEE-3 into a heliocentric orbit at the inner Lagrangian point in August, 1978, the UCB/LASL experiment has detected and recorded 12 gamma-ray bursts, including the unusually intense burst of November 4, 1978, which exhibited most of the classical gamma-ray burst characteristics, the intense burst of November 19, 1978, with an atypical time history and an unusually hard spectrum, and the extended burst of March 7, 1979. The spectral and temporal data demonstrate the diverse nature of the gamma-ray burst phenomenon, and are currently being combined with those of the Pioneer Venus Orbiter and Venera 11 and 12 to obtain accurate burst locations.
Evans, W. D.↗
Periodicity of the gamma-ray transient event of 5 March 1979
An unusual gamma-ray burst event was observed on 5 March 1979 by nine different spacecraft. The position of the event has been accurately determined as r.a. = 5 h 25.95 min, dec = -66 deg 07.1 arcmin (epoch 1950.0), coincident with the location of the supernova remnant N49 in the Large Magellanic Cloud. The burst was of very high intensity, and if isotropic and located at the distance (approximately 55 kpc) of N49 had a peak luminosity of greater than 10 to the 44th erg/sec. Even more interesting is the obvious 8-s periodicity of the event, following the initial very intense outburst. The time history and power spectrum of this event as determined from Pioneer Venus Orbiter data is here reported.
Terrell, J.↗
Time exposure studies on stress corrosion cracking of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651, and titanium 6Al-4V
The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651 and titanium 6Al-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 7) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity), and demineralized distilled water. Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, titanium stressed specimens showed no reactions to its environment. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 and aluminum 2014-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl), while aluminum 2219-T87 seem to resist stress corrosion cracking in sodium chloride at three levels of stress (25%, 50%, and 75% Y.S.). In organic fluids of methyl, ethyl, and iso-propyl alcohol, 2014-T6 and 7075-T651 did not fail by SCC; but 2014-T651 was susceptible to SCC in methly alcohol, but resistant in ethyl alcohol, iso-propyl alcohol and demineralized distilled water.
Terrell, J.↗
Time exposure studies on stress corrosion cracking of aluminum 2014-T6, aluminum 7075-T651, and titanium 6Al-4V
The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 7075-T651 and titanium 6A1-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 6) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity). Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, a similar observation was not noted for titanium stressed specimens. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl); while they (both alloys) seem to resist stress corrosion cracking in methyl alcohol, ethyl alcohol, iso-propyl alcohol, and demineralized distilled water. Titanium 6A1-4V showed some evidence of susceptibility to SCC in methanol, while no such susceptibility was exhibited in ethanol, iso-propyl alcohol and demineralized distilled water.
Terrell, J.↗