A design of a two-dimensional,multimode RM experiment on OMEGA-EP

An experiment, meant to investigate the evolution of Richtmyer–Meshkov (RM) instability in the bubble merger regime and at low Atwood number (A～0.3), is proposed and theoretically analyzed. This experiment is intended to provide a direct measurement of the two-dimensional bubble-front shape and spectrum evolution in time, along with the power-law coefficient for bubble-front growth (θ_b). It is unique in its use of a well-characterized two-dimensional initial perturbation, allowing controlled initiation and growth of the instability. The proposed design assures a significant time scale of steady RM conditions, taking advantage of the long drive (～30 ns) available on the OMEGA-EP laser facility, along with neither a Rayleigh–Taylor (RT) component nor shock-proximity effects, due to the use of a light to heavy configuration. Multimode RM growth for the proposed configuration has been analyzed using two-dimensional, direct numerical simulations, showing significant mode coupling and convergence to power-law growth of the bubble front. The effects of two-dimensional rarefactions were also investigated, and it was found that they introduce no major uncertainties or hazards to the physics. An experiment of this kind has not yet been performed, and therefore would serve to validate numerical results and analytical models presented in literature.     

Hyperovals in nets of small degree

The existence of an r‐net of order n with a hyperoval is proved for r = 5 when n ≥ 63; for r = 7 when n ≥ 84; for r = 9 when n ≥ 59,573 and for r = 15 when n ≥ 1, 873,273. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 322–334, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10018     

An NMR investigation of the importance of intramolecular hydrogen bonding in determining the conformational equilibrium of ethylene glycol in solution

Although conformational analysis by NMR of ethylene glycol indicates generally strong preferences for the gauche conformation in solvents ranging from water to chloroform, the bulk of the NMR evidence indicates that intramolecular hydrogen bonding between the hydroxyl groups is unlikely to be a significant factor in determining that preference, except possibly in fairly non-polar solvents. The 'gauche effect' is clearly very important, especially in aqueous solution.     

Liquid-phase oxidation of alkylaromatics by a H-atom transfer mechanism with a new heterogeneous CoSBA-15 catalyst

A new pseudo-tetrahedral Co(II) complex has been grafted onto the surface of SBA-15 and successfully utilized for the catalytic oxidization of alkylaromatic substrates with tert-butyl hydroperoxide (TBHP)via an H-atom transfer mechanism.     

Impact of frustrated singularities on magnetic island evolution

The growth of magnetic islands is explored using the magnetohydrodynamic model in a simple slab system in which the value of the tearing mode stability parameter Delta' can be varied continuously. Unless the system is close to marginal stability reconnection is controlled by Sweet-Parker current layers, whose formation is a consequence of the inherent singular structure of magnetic island equilibria.     

Catastrophe model for fast magnetic reconnection onset

A catastrophe model for the onset of fast magnetic reconnection is presented that suggests why plasma systems with magnetic free energy remain apparently stable for long times and then suddenly release their energy. For a given set of plasma parameters there are generally two stable reconnection solutions: a slow (Sweet-Parker) solution and a fast (Alfvénic) Hall reconnection solution. Below a critical resistivity the slow solution disappears and fast reconnection dominates. Scaling arguments predicting the two solutions and the critical resistivity are confirmed with two-fluid simulations.     

Fine structure of the 1s3p 3PJ level in atomic 4He: theory and experiment

The fine structure intervals in helium have been the focus of many theoretical and experimental studies in recent years with most of them concentrating on the 1s2p (3)P(J) levels. Here, we report on a theoretical calculation and an experimental determination of the 1s2p (3)P(J) fine structure intervals. The values from the theoretical calculation are 8113.730(6) and 658.801(6) MHz for the nu(01) and nu(12) intervals, respectively. The laser spectroscopic measurement reported here yields 8113.714(28) and 658.810(18) MHz for these intervals and is in excellent agreement with the theoretical calculation. Both, however, disagree significantly with the previous most precise experimental results.     

Pairwise balanced designs whose line sizes do not divide six

A proper PBD(L, v) is a pairwise balanced design (with λ = 1) on v points whose line sizes are less than v and do not divide six. The existence or nonexistence of a proper PBD(L, v) is determined for all v different from thirty.     

The optical activity of the H-stretching vibrational modes of calycanthine and IRCD determinations of absolute configuration

The infrared circular dichroism (IRCD) due to the H-stretching vibrational modes of calycanthine originates principally from chromophore-substituent coupling and not from the degenerate interchromophore coupling mechanism particular to dissymmetric dimers. The general non-degenerate mechanism provides a procedure for the determination of absolute configuration from the IRCD associated with a localised characteristic vibrational mode.