What is SETI?
This paper describes the efforts of SETI that are going on around the world. It presents a brief rationale for the choice of methodology and the limits that can be set on the basis of such results to date.
Exobiology↗
Biomedical subjects
J Tarter
Publications and source records attributed to J Tarter.
In vivo localized proton NMR spectroscopy of thiamine-deficient rat brain.
Thiamine deficiency (TD) in rats produces lesions similar to those found in humans suffering from Wernicke's encephalopathy, an organic mental disorder associated with alcoholism. Male Sprague-Dawley rats (n = 29) were deprived of thiamine via a regimen of thiamine-deficient chow and daily intraperitoneal injections of the thiamine antagonist pyrithiamine hydrobromide. Spectra were obtained by using the STEAM sequence. No significant change occurred in the ratio of Cr/NAA, while the ratio of Cho/NAA declined significantly (60 +/- 11%) on Day 14. Eleven rats received intraperitoneal injections of thiamine hydrochloride at the end of 12 days, and dose-dependent recovery in Cho/NAA was observed.
Alcohol Amnestic Disorder↗
Frequency and experience with carcinoma of the thyroid at a private, a Veterans Administration, and a university hospital.
We evaluated the treatment experiences with thyroid carcinoma at a private, a Veterans Administration, and a University hospital to determine the frequency, treatment, and outcome of patients with this uncommon malignant tumor. All 120 patients with thyroid carcinoma were identified through hospital tumor registries between 1953 and 1988, representing 0.3% of the total cancer registry cases during this period. Well-differentiated carcinoma of the thyroid represented 73%, medullary carcinoma 7%, poorly differentiated carcinoma 18%, and Hürthle cell carcinoma 2% of histologic varieties. Seventy-eight percent of patients were treated initially by surgery or by surgery plus postoperative irradiation. The remaining patients received other treatment. At 10 years after treatment, 90% of patients with well-differentiated carcinoma survived, while only 20% of patients with medullary and poorly differentiated carcinoma survived. Sixty percent of recurrences for all histologic types appeared within the first 12 months after treatment. Patients with well-differentiated carcinoma had sporadic recurrences over a 21-year-period. Recognition of these time intervals allows for better follow-up management.
Adenocarcinoma↗
Radio frequency interference at Jodrell Bank Observatory within the protected 21 cm band.
Radio frequency interference (RFI) will provide one of the most difficult challenges to systematic Searches for Extraterrestrial Intelligence (SETI) at microwave frequencies. The SETI-specific equipment is being optimized for the detection of signals generated by a technology rather than those generated by natural processes in the universe. If this equipment performs as expected, then it will inevitably detect many signals originating from terrestrial technology. If these terrestrial signals are too numerous and/or strong, the equipment will effectively be blinded to the (presumably) weaker extraterrestrial signals being sought. It is very difficult to assess how much of a problem RFI will actually represent to future observations, without employing the equipment and beginning the search. In 1983 a very high resolution spectrometer was placed at the Nuffield Radio Astronomy Laboratories at Jodrell Bank, England. This equipment permitted an investigation of the interference environment at Jodrell Bank, at that epoch, and at frequencies within the 21 cm band. This band was chosen because it has long been "protected" by international agreement; no transmitters should have been operating at those frequencies. The data collected at Jodrell Bank were expected to serve as a "best case" interference scenario and provide the minimum design requirements for SETI equipment that must function in the real and noisy environment. This paper describes the data collection and analysis along with some preliminary conclusions concerning the nature of the interference environment at Jodrell Bank.
Astronomy↗
Narrow polarized components in the OH 1612-MHz maser emission from supergiant OH-IR sources.
High-resolution OH 1612-MHz spectra are presented of the supergiant OH-IR sources VY CMa, VX Sgr, IRC 10420 and NML Cyg. The spectra have a resolution of 300 Hz. Narrow components in the spectra have linewidths as small as 550 Hz (0.1 km s-1) but there is no evidence for components narrower than this. These results are in accord with present understanding of maser line-narrowing and of the physical conditions in the OH maser regions. Many of the narrow components have an appreciable degree of circular polarization which is not apparent at the lower frequency resolutions usually employed. The circular polarization indicates the presence of magnetic fields of approximately 1 mG in the circumstellar envelopes, at distances of approximately 3x10(16) cm from the central stars. These fields are strong enough to influence the outflow from the stars, and may help to explain some of the asymmetries which are seen in their circumstellar envelopes.
Astronomical Phenomena↗
Using the Very Large Array (VLA) and other radio telescopes to perform a parasitic Search for Extraterrestrial Intelligence (SETI).
This paper describes several attempts to utilize various radio telescopes in a manner that we term "parasitic," that is in a manner that does not interrupt or seriously impact the standard astronomical observing programs in progress at the radio observatories. In the extreme case, only recorded astronomical data are accessed off-line, after the fact, without any burden on the observatory at all.
Astronomy↗
"Signal" search for intelligence in the galactic nucleus with the array of the Lowlands.
In August, 1981, the Westerbork Synthesis Radio Telescope was used for 4 h to search for narrowband pulsing radio beacons in the direction of the Galactic Center. By using both the spatial discrimination and temporal stability available to an interferometric measurement, weak intermittent signals can be detected even in the face of the strong, naturally caused radiation from this region. A radio beacon within our bandwidth, centered on the 21 cm neutral hydrogen line, would be recognizable if it had a repetition period between 40 sec and 1/2 h. The rms sensitivity to point sources was approximately 50 mJy/cycle, and the detection limit was 500 mJy/cycle. The limit degrades for pulse widths < 0.02s. No repetitive signals were found. For a swept, narrow-band radio beacon constrained to the Galactic Disk (beamwidth = 0.02 rad), our detection limit corresponds to a transmitter power of 10(11) MW at the Galactic Center.
Astronomy↗
Detection of the Earth with the SETI microwave observing system assumed to be operating out in the galaxy.
This paper estimates the maximum range at which radar signals from the Earth could be detected by a search system similar to the NASA Search for Extraterrestrial Intelligence Microwave Observing Project (SETI MOP) assumed to be operating out in the galaxy. Figures are calculated for the Targeted Search, and for the Sky Survey parts of the MOP, both operating, as currently planned, in the second half of the decade of the 1990s. Only the most powerful terrestrial transmitters are considered, namely, the planetary radar at Arecibo in Puerto Rico, and the ballistic missile early warning systems (BMEWS). In each case the probabilities of detection over the life of the MOP are also calculated. The calculation assumes that we are only in the eavesdropping mode. Transmissions intended to be detected by SETI systems are likely to be much stronger and would of course be found with higher probability to a greater range. Also, it is assumed that the transmitting civilization is at the same level of technological evolution as ours on Earth. This is very improbable. If we were to detect another technological civilization, it would, on statistical grounds, be much older than we are and might well have much more powerful transmitters. Both factors would make detection by the NASA MOP a much more likely outcome.
Astronomy↗
A reply from Earth?
An approach is proposed to developing a message from Humankind to extraterrestrial intelligence if we detect it.
Astronomy↗
Project Phoenix and beyond. Pesek Lecture.
Although there are no federally funded projects at this time, SETI (the search for extraterrestrial intelligence) is a vigorous exploratory science. There are currently eight observational programs on telescopes around the world, of which the Phoenix Project is the most comprehensive. Most of these projects are rooted in the conclusions of the pioneering studies of the early 1970's that are summarized in the Cyclops Report. Technology has experienced an exponential growth over the past two and a half decades. It is reasonable to reassess the Cyclops conclusions as SETI enters the next century. Listening for radio signals is still the preferred method of searching, however new technologies are making searches at other wavelengths possible and are modifying the ways in which the radio searches can and should be conducted. It may be economically feasible to undertake the construction of very large telescopes that can simultaneously provide multiple beams on the sky for use by SETI and the radioastronomy community.
Astronomy↗