Acceleration of dust particles by low-frequency Alfv\'en waves

We investigate the efficiency of acceleration of charged dust particles by low-frequency Alfv\'en waves in nonlinear approximation. We show that the longitudinal acceleration of dust particles is proportional to the square of the soliton amplitude $O(|b_m|^2)$, while the transversal acceleration is of $O(|b_m|)$. In the conditions of the interstellar medium the resulting velocity of dust particles can reach 0.3 to 1 km s$^{-1}$.Comment: 8 pages, no figs, accepted in Phys. Lett.

Nonlinear dynamics of large amplitude dust acoustic shocks and solitary pulses in dusty plasmas

We present a fully nonlinear theory for dust acoustic (DA) shocks and DA solitary pulses in a strongly coupled dusty plasma, which have been recently observed experimentally by Heinrich et al. [Phys. Rev. Lett. 103, 115002 (2009)], Teng et al. [Phys. Rev. Lett. 103, 245005 (2009)], and Bandyopadhyay et al. [Phys. Rev. Lett. 101, 065006 (2008)]. For this purpose, we use a generalized hydrodynamic model for the strongly coupled dust grains, accounting for arbitrary large amplitude dust number density compressions and potential distributions associated with fully nonlinear nonstationary DA waves. Time-dependent numerical solutions of our nonlinear model compare favorably well with the recent experimental works (mentioned above) that have reported the formation of large amplitude non-stationary DA shocks and DA solitary pulses in low-temperature dusty plasma discharges.Comment: 9 pages, 4 figures. To be published in Physical Review

A Polyaromatic Receptor with an Ethereal Fence that Directs K\u3csup\u3e+\u3c/sup\u3e for Effective Cation−π Interaction

We have designed and synthesized a HAB-based receptor with six ethereal oxygens on one face of the central benzene ring by a trimerization of a diarylacetylene in which the ethereal oxygens are tied together with a tetramethylene bridge. This unique amphiphilic receptor allows an efficient binding of a single potassium cation by a synergistic interaction with the polar ethereal fence and with the central benzene ring via cation−π interaction. Furthermore, the ready accessibility of this unique receptor with a bipolar binding pocket will allow the exploration of its usage for developing efficient sensing devices for various metal cations

Electron Transfer Prompted Ejection of a Tightly Bound K\u3csup\u3e+\u3c/sup\u3e from the Ethereal Cavity of a Hexaarylbenzene-Based Receptor

Synthesis of a pair of rotamers (9u/9s) of a hexaarylbenzene derivative containing six (cofacially arranged) electroactive 2,5-dimethoxytolyl groups is described. The toroidal electronic stabilization due to the circular arrangement of aryl groups in 9u/9s leads to the observation of multiple (reversible) oxidation waves and lowering of their Eox1 by ∼250 mV relative to model compounds. The binding of K+ to symmetrical rotamer 9s was monitored by an electrochemical method and further confirmed by X-ray crystallography

Terphenyl Crowns: a New Family of Receptors Containing Ethereal Canopies that Direct Potassium Cation onto Benzenoid Platforms for Cation–π Interactions

We have synthesized three simple and versatile terphenyl crowns (TC) receptors containing ethereal canopies that direct a potassium cation for efficient cation–π interactions as established by 1H NMR spectroscopy and by isolation and X-ray crystallography of their K+ salts

Symmetry Constraints in Inflation, α\alpha-vacua, and the Three Point Function

The Ward identities for conformal symmetries in single field models of inflation are studied in more detail in momentum space. For a class of generalized single field models, where the inflaton action contains arbitrary powers of the scalar and its first derivative, we find that the Ward identities are valid. We also study a one-parameter family of vacua, called $\alpha$-vacua, which preserve conformal invariance in de Sitter space. We find that the Ward identities, upto contact terms, are met for the three point function of a scalar field in the probe approximation in these vacua. Interestingly, the corresponding non-Gaussian term in the wave function does not satisfy the operator product expansion. For scalar perturbations in inflation, in the $\alpha$-vacua, we find that the Ward identities are not satisfied. We argue that this is because the back-reaction on the metric of the full quantum stress tensor has not been self-consistently incorporated. We also present a calculation, drawing on techniques from the AdS/CFT correspondence, for the three point function of scalar perturbations in inflation in the Bunch-Davies vacuum.Comment: 51 pages, 3 figures, 6 appendices. v3: JHEP version. Minor typos correcte