Astronomer

Landolt-Bornstein "Zahlenwerte und Funktionen aus Physik, Chemie, Astronomic, Geophysik, und Technik," 6th ed., Vol. II (2a, 2b, 2c), Vol. IV (4b), Springer Verlag, Berlin, beginning 1950. 

Rather different circumstances are encountered when considering THz remote sensing of extraterrestrial sources. The major source of THz opacity in the Earth s atmosphere is water vapour, and from either high, dry mountain sites or from space there are windows in which the background becomes very small. Incoherent instruments which detect the faint emission from astronomical sources can therefore be considerably more sensitive than their laboratory... 

Figure Bl.4.2. (A) Basic components of an astronomical heterodyne receiver. The photomicrograph in (B) presents the heart of a quasi-optical SIS mixer and its associated superconducting timing circuits, while the image in (C) shows the fiilly assembled mixer, as it would be incorporated into a low-temperature cryostat (J Zmuidzinas, private conmumication).

At that time, fire, water, soil, and air represented the pillars of the four-element apprenticeship. Metals were extracted as pure elements in the present sense), even if they were not yet recognized as such. They were designated by astronomical and astrological symbols. 

One hypothesis says that fluorine can be substituted for hydrogen wherever it occurs in organic compounds, which could lead to an astronomical number of new fluorine compounds. Compounds of fluorine with rare gases have now been confirmed in fluorides of xenon, radon, and krypton. 

Figure 5.1 2 The J = 1 — 0 transition of cyanodiacetylene observed in emission in Sagittarius B2. (Reproduced, with permission, from Broton, N. W., MacLeod, J. M., Oka, T, Avery, L. W., Brooks, J. W., McGee, R. X. and Newton, L. M., Astrophys. J., 209, L143, 1976, published by the University of Chicago Press 1976 The American Astronomical Society)...

In the x-ray portion of the spectmm, scientific CCDs have been utilized as imaging spectrometers for astronomical mapping of the sun (45), galactic diffuse x-ray background (46), and other x-ray sources. Additionally, scientific CCDs designed for x-ray detection are also used in the fields of x-ray diffraction, materials analysis, medicine, and dentistry. CCD focal planes designed for infrared photon detection have also been demonstrated in InSb (47) and HgCdTe (48) but are not available commercially. 

For any given protein, the number of possible conformations that it could adopt is astronomical. Yet each protein folds into a unique stmcture totally deterrnined by its sequence. The basic assumption is that the protein is at a free energy minimum however, calometric studies have shown that a native protein is more stable than its unfolded state by only 20—80 kj/mol (5—20 kcal/mol) (5). This small difference can be accounted for by the favorable... 

Sputtered silver mirrors are used for solar energy (qv) collectors and astronomical telescope mirrors. Approximately 3 t/yr of silver are used in the United States for low emissivity windows. 

Proteins are macromolecules that play many roles such as serving as enzymes or components of cell membranes and muscle. The antibodies that protect against invasion by foreign substances are themselves proteins. There are twenty-odd amino acids found regularly in most naturally occurring proteins. Because of the great length of protein chains and the various sequences of amino acids, the theoretic number of possible proteins is astronomical. The amino acid sequence is referred to as the primaiy structure of a protein. The pol eptide... 

Raikes, S.A., and Ahrens, T.J. (1979b), Post-Shock Temperatures of Minerals, Geophys. J. Roy. Astronom. Soc. 58, 717-748. 

For a polypeptide chain of 100 residues in length, a rather modest size, the number of possible sequences is 20 , or because 20 = lO, lO unique possibilities. These numbers are more than astronomical Because an average protein molecule of 100 residues would have a mass of 13,800 daltons (average molecular mass of an amino acid residue = 138), lO such molecules would have amass of 1.38 X lO " daltons. The mass of the observable universe is estimated to be 10 proton masses (about 10 daltons). Thus, the universe lacks enough material to make just one molecule of each possible polypeptide sequence for a protein only 100 residues in length. 

Proteins have unique amino acid sequences, and it is this uniqueness of sequence that ultimately gives each protein its own particular personality. Because the number of possible amino acid sequences in a protein is astronomically large, the probability that two proteins will, by chance, have similar amino acid sequences is negligible. Consequently, sequence similarities between proteins imply evolutionary relatedness. 

Impure, native platinum seems to have been used unwittingly by ancient Egyptian craftsmen in place of silver, and was certainly used to make small items of jewellery by the Indians of Ecuador before the Spanish conquest. The introduction of the metal to Europe is a complex and intriguing story. In 1736 A. de Ulloa, a Spanish astronomer and naval officer, observed an unworkable metal, platina (Spanish, little... 

Thus, astronomers also suffer from the three-body problem when they try to study the motion of the planets round the sun. They are lucky in that the gravitational force between bodies A and B goes as... 

Sstig, a. branched, branchy knotted, gnarled. Astronom, m. astronomer. astroDomisch, a. astronomical, astrophysikalisch, a. astrophysical. asymmetrisch, a. asymmetric, asymmetrical, asymptotisch, a. asymptotic, asynchron, a. asynchronous, aszendent, a. (Mtn.) primary. 

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