Nitrogen and noble gases in a glass sample from the LEW88516 shergottite

Abstract— A glass separate from the LEW88516 shergottite was analyzed by step-wise combustion for N and noble gases to determine whether it contained trapped gas similar in composition to the martian atmosphere-like component previously observed in lithology C of EETA79001. Excesses of ⁴⁰Ar and ¹²⁹Xe were in fact observed in this glass, although the amounts of these excesses are ≤20% of those seen in the latter meteorite, and are comparable to the amounts seen in whole-rock analyses of LEW88516. The isotopic composition of N in LEW88516 does not show an enrichment in ¹⁵N commensurate with the amount of isotopically-heavy N expected from the noble gases excesses. One must posit some extreme assumptions about the nature of the N components present in LEW88516 in order to allow the presence of the trapped nitrogen component. Alternatively, the N has somehow been decoupled from the noble gases, and was either never present or has been lost.     

Solar wind noble gases and nitrogen in metal from lunar soil 68501

Abstract Noble gases and N were analyzed in handpicked metal separates from lunar soil 68501 by a combination of step-wise combustions and pyrolyses. Helium and Ne were found to be unfractionated with respect to one another when normalized to solar abundances, for both the bulk sample and for all but the highest temperature steps. However, they are depleted relative to Ar, Kr and Xe by at least a factor of 5. The heavier gases exhibit mass-dependent fractionation relative to solar system abundance ratios but appear unfractionated, both in the bulk metal and in early temperature steps, when compared to relative abundances derived from lunar ilmenite 71501 by chemical etching, recently put forward as representing the abundance ratios in solar wind. Estimates of the contribution of solar energetic particles (SEP) to the originally implanted solar gases, derived from a basic interpretation of He and Ne isotopes, yield values of about 10%. Analysis of the Ar isotopes requires a minimum of 20% SEP, and Kr isotopes, using our preferred composition for solar wind Kr, yield a result that overlaps both of these values. It is possible to reconcile the data from these gases if significant loss of solar wind Ar, Kr and presumably Xe has occurred relative to the SEP component, most likely by erosive processes that are mass independent, although mass-dependent losses (Ar > Kr > Xe) cannot be excluded. If such losses did occur, the SEP contribution to the solar implanted gases must have been no more than a few percent. Nitrogen is a mixture of indigenous meteoritic N, whose isotopic composition is inferred to be relatively light, and implanted solar N, which has probably undergone diffusive redistribution and fractionation. If the heavy noble gases have not undergone diffusive loss, then N/Ar in the solar wind can be inferred to be at least several times the accepted solar ratio. The solar wind N appears, even after correction for fractionation effects, to have a minimum δ¹⁵N value ≥+150‰ and a more probable value ≥+200‰.     

Relative-rate study of the gas-phase reaction of hydroxy radicals with difunctional organic nitrates at 298 K and atmospheric pressure

Rate coefficients for the reactions of difunctional nitrates with atmospherically important OH radicals are not currently available in the literature. This study represents the first determination of rate coefficients for a number of C(3) and C(4) carbonyl nitrates and dinitrates with OH radicals in a 38 l glass reaction chamber at 1000 mbar total pressure of synthetic air by 298±2 K using a relative kinetic technique.The following rate coefficients (in units of 10^-12 cm³ molecule^-1 s^-1) were obtained: 1,2-propandiol dinitrate, <0.31; 1,2-butandiol dinitrate, 1.70±0.32; 2,3-butandiol dinitrate, 1.07±0.26; -nitrooxyacetone, <0.43; 1-nitrooxy-2-butanone, 0.91±0.16; 3-nitrooxy-2-butanone, 1.27±0.14; 1,4-dinitrooxy-2-butene, 15.10±1.45; 3,4-dinitrooxy-1-butene, 10.10±0.50.The possible importance of reaction of OH as an atmospheric sink for the compounds compared to other loss processes is considered.     

Heat-Stress Regions in Israel

Summary The data of 20 climatic stations have been examined to determine heat-stress regions in Israel. The data was interpolated and a model was developed for the calculation of direct and diffuse solar radiation. Thermal perception was calculated according to the energy-balance model of man which considers all relevant energy fluxes affecting the human thermo-regulatory system. It is based on the ‘Comfort Equation’ of Fanger (1972) and the ‘Klima-Michel-Modell’ of Jendritzky et al. (1990). Earlier approaches for the assessment of thermal environmental conditions have been done by Sohar (1980), based on the discomfort index. The average daily duration of severe heat stress which a person is exposed to during various activities in summer months has been analyzed in order to classify the thermal environmental conditions in Israel. Statistical evaluations have led to six heat-stress clusters and regions, respectively. A model calculating the spatial development of climatic data between two measuring stations was set up and served to determine the location of the distinctions between the regions. The resulting heat-stress map shows the different heat-stress regions in Israel. The regions are characterized by graphs that show the average monthly duration of light, medium and severe heat-stress. The average duration of severe heat-stress varies in July from approximately 3 hours along the coastal strip and in the higher mountain regions to approximately 13 hours in the Arava. Received September 3, 1996 Revised June 23, 1997     

A large radio nebula around P Cygni

We present a large set of radio observations of the luminous blue variable P Cygni. These include two 6-cm images obtained with MERLIN which spatially resolve the 6-cm photosphere, monitoring observations obtained at Jodrell Bank every few days over a period of two months, and VLA observations obtained every month for seven years. This combination of data shows that the circumstellar environment of P Cyg is highly inhomogeneous, that there is a radio nebula extending to almost an arcminute from the star at 2 and 6 cm, and that the radio emission is variable on a time-scale no longer than one month, and probably as short as a few days. This short-time-scale variability is difficult to explain. We present a model for the radio emission with which we demonstrate that the star has probably been losing mass at a significant rate for at least a few thousand years, and that it has undergone at least two major outbursts of increased mass loss during the past two millenia.     

V. K. Ting

Ohne Zusammenfassung     

Interactions between oceanic and gravity tides,as analysed from world-wide earth tide observations and ocean models

The problem of interactions between earth tides and oceanic tides is rather complex as it involves effects of newtonian attraction, loading and associated change of earth potential, tangential pressure and friction on the moving ocean floor which are not always easy to evaluate, principally for coastal or island stations. This paper takes advantage of two facts:

1. By the end of 1983 the International Center of Earth Tides has collected and evaluated a considerable amount of data from 223 stations including those of the Trans World Profiles developed by the same group of authors (102 stations). This ensures, for the first time, a World wide distribution including the tropical areas and the southern hemisphere.
2. In 1978–80, new oceanic cotidal maps of high quality, established by E.W. Schwiderski, became available.

We have calculated, for the eight principal tidal waves, the correlations between the observed gravity variations and those resulting from a calculation based upon the Schwiderski maps. This correlation is highly significant. At the level of accuracy of the best transportable gravimeters the agreement is perfect except at a few places where effects of lateral heterogeneities in the mantle can perhaps be suspected. These cotidal maps can therefore be safely used as working standards for other geodetic and geophysical applications.