Trace element contents of selected antarctic meteorites, 1

Data are reported for volatile/mobile Ag, As, Au, Bi, Cd, Co, Cs, Cu, Ga, In, Rb, Sb, Se, Te, T1 and Zn in exterior and/or interior samples of four Antarctic meteorites: 77005 (unique achondrite); 77257 (unreilite); 77278 (L3); 77299 (H3). Exterior samples reflect contamination and/or leaching by weathering but trace element (ppm-ppt) contents in interior samples seem reasonable for representatives of these rare meteoritic types. The 77005 achondrite seems related to shergottites; other samples extend compositional ranges previously known for their types. With suitable precautions, Antarctic meteorite finds yield trace element data as reliable as those obtained from previously known falls

Stimulated Raman Adiabatic Passage (STIRAP) Among Degenerate-Level Manifolds

We examine the conditions needed to accomplish stimulated Raman adiabatic passage (STIRAP) when the three levels (g, e and f) are degenerate, with arbitrary couplings contributing to the pump-pulse interaction (g - e) and to the Stokes-pulse interaction (e-f). We show that in general a sufficient condition for complete population removal from the g set of degenerate states for arbitrary, pure or mixed, initial state is that the degeneracies should not decrease along the sequence g, e and f. We show that when this condition holds it is possible to achieve the degenerate counterpart of conventional STIRAP, whereby adiabatic passage produces complete population transfer. Indeed, the system is equivalent to a set of independent three-state systems, in each of which a STIRAP procedure can be implemented. We describe a scheme of unitary transformations that produces this result. We also examine the cases when this degeneracy constraint does not hold, and show what can be accomplished in those cases. For example, for angular momentum states when the degeneracy of the g and f levels is less than that of the e level we show how a special choice for the pulse polarizations and phases can produce complete removal of population from the g set. Our scheme can be a powerful tool for coherent control in degenerate systems, because of its robustness when selective addressing of the states is not required or impossible. We illustrate the analysis with several analytically solvable examples, in which the degeneracies originate from angular momentum orientation, as expressed by magnetic sublevels.Comment: 21 pages, 17 figure

Labile trace elements and cosmogenic radionuclides in chondritic hosts of three consortium igneous inclusions

Three ordinary chondrites from the Yamato Mountains (Y) region of Antarctica contain cm-sized igneous inclusions being studied by a consortium. RNAA data for the labile elements Ag, Bi, Cd, Cs, Ga, In, Rb, Sb, Se, Te, Tl and Zn, and refractory Au and U in the L6 hosts of Y-75097 and Y-793241 indicate that each experienced at least one preterrestrial, high-temperature episode. This heating occurred during formation of the igneous inclusions and/or as a result of the severe shock that affected most equilibrated L chondrites. Cosmogenic 720ka ^Al, and 301ka^Cl (which are determined by AMS) in metal from these two meteorites and nominal terrestrial ages (based on ^Cl) hint that the L6 chondrites are not paired but are inconclusive in this regard. RNAA data for the H chondrite host of Y-794046 generally resemble those of other H4-6 chondrites : its contents of cosmogenic radionuclides in general, and its ^Cl content, in particular, correspond to a nominal terrestrial age of 70±60ka

Some properties of nilpotent groups

Property S, a finiteness property which can hold in infinite groups, was introduced by Stallings and others and shown to hold in free groups. In [2] it was shown to hold in nilpotent groups as a consequence of a technical result of Mal'cev. In that paper this technical result was dubbed property R. Hence, more generally, any property R group satisfies property S. In [7] it was shown that property R implies the following (labeled there weak property R) for a group G: If G₀ is any subgroup in G and G₀* is any homomorphic image of G₀, then the set of torsion elements in G₀* forms a locally finite subgroup. It was left as an open question in [7] whether weak property R is equivalent to property R. In this paper we give an explicit counterexample thereby proving that weak property R is strictly weaker than property R

Survey of generalized pregroups and a question of Reinhold Baer

There has been recent interest in Stallings’ Pregroups. (See [2] and [12].) This paper gives a survey of generalized pregroups. We also answer a question of Reinhold Baer [1] on pregroups and answer a generalization of this question for generalized pregroups