Looking at saturation effects with production in pA collisions

We compute the inclusive differential cross section production of the pseudo-scalar meson η^′ in high-energy proton-nucleus (pA) collisions. We use an effective coupling between gluons and η^′ meson to derive a reduction formula that relates the η^′ production to a field-strength tensor correlator. We take into account saturation effects on the nucleus side by using the Color Glass Condensate formalism to evaluate this correlator. We derive new results for Wilson line - color charges correlators in the McLerran-Venugopalan model needed in the computation of η^′ production. The unintegrated parton distribution functions are used to characterize the gluon distribution inside the proton. We show that the cross section is sensitive to saturation effects so it can be utilized to estimate the value of the saturation scale.     

The foreign language cocktail party problem: Energetic and informational masking effects in non-native speech perception

Studies comparing native and non-native listener performance on speech perception tasks can distinguish the roles of general auditory and language-independent processes from those involving prior knowledge of a given language. Previous experiments have demonstrated a performance disparity between native and non-native listeners on tasks involving sentence processing in noise. However, the effects of energetic and informational masking have not been explicitly distinguished. Here, English and Spanish listener groups identified keywords in English sentences in quiet and masked by either stationary noise or a competing utterance, conditions known to produce predominantly energetic and informational masking, respectively. In the stationary noise conditions, non-native talkers suffered more from increasing levels of noise for two of the three keywords scored. In the competing talker condition, the performance differential also increased with masker level. A computer model of energetic masking in the competing talker condition ruled out the possibility that the native advantage could be explained wholly by energetic masking. Both groups drew equal benefit from differences in mean F0 between target and masker, suggesting that processes which make use of this cue do not engage language-specific knowledge.     

Geometry of optimality conditions and constraint qualifications

Certain types of necessary optimality conditions for mathematical programming problems are equivalent to corresponding regularity conditions on the constraint set. For any problem, a certain natural optimality condition, dependent upon the particular constraint set, is always satisfied. This condition can be strengthened in numerous ways by invoking appropriate regularity assumptions on the constraint set. Results are presented for Euclidean spaces and some extensions to Banach spaces are given.This work was supported in part by the Office of Naval Research, Contract No. N00014-67-A-0321-0003 (NR-047-095).     

The reaction of the cyclooctatetraenyl dianion and chlorotrimethylsilane; synthesis and decomposition studies of 5,8-bis(trimethylsilyl)cyclooctatriene

On the basis of PMR decoupling experiments and thermal decomposition studies, the reaction of the cyclooctatetraenyl dianion and chlorotrimethylsilane produces 5,8-bis(trimethylsilyl)-l,3,6-cyclooctatriene, in contrast to a previous report which suggested 7,8-bis(trimethylsilyl)-l,3,5-cyclooctatriene. The product is stable at room temperature in vacuo but undergoes decomposition (isomerization) reactions at higher temperatures or in contact with air.     

Fundamental relationships in the theory of electric multipole moments and multipole polarizabilities in static fields

New derivations are given of equations relating molecular electric multipole moments and polarizabilities of general order to the electrostatic energy. The unabridged moment convention is shown to yield relatively simple relations between derivatives of the energy with respect to field gradients and the multipole moments and polarizabilities. Care is taken to distinguish various forms of these derivatives, and one form leads to a proof of a general symmetry of polarizability tensors with respect to permutations of rank indices. The condition of internal equilibrium is shown to be fundamental to the existence of this symmetry. The transformation of multipole moment and polarizability tensors under translation of the coordinate origin is expressed in relatively simple general form. The traceless multipole and polarizability tensors of Buckingham and McLean and Yoshimine are obtained as linear combinations of the unabridged tensors and their traces.     

The spectra of helium-like ions in laser-produced plasmas

We calculate intensities of lines arising from the n = 2 and n = 3 levels of highly-charged, helium-like ions in very dense plasmas. We determine the importance of recombination and cascading, and of radiation trapping, on certain line-intensity ratios, and we illustrate the relevance of these calculations to laser-plasma diagnostics. Finally, we outline the pitfalls inherent, at very high densities, in some other techniques commonly used to interpret plasma spectra.