7,448 research outputs found
Atomic decomposition and interpolation for Hardy spaces of noncommutative martingales
We prove that atomic decomposition for the Hardy spaces h_1 and H_1 is valid
for noncommutative martingales. We also establish that the conditioned Hardy
spaces of noncommutative martingales h_p and bmo form interpolation scales with
respect to both complex and real interpolations
Reactive processing of formaldehyde and acetaldehyde in aqueous aerosol mimics: Surface tension depression and secondary organic products
The reactive uptake of carbonyl-containing volatile organic compounds (cVOCs)
by aqueous atmospheric aerosols is a likely source of particulate organic
material. The aqueous-phase secondary organic products of some cVOCs are
surface-active. Therefore, cVOC uptake can lead to organic film formation at
the gas-aerosol interface and changes in aerosol surface tension. We examined
the chemical reactions of two abundant cVOCs, formaldehyde and acetaldehyde, in
water and aqueous ammonium sulfate (AS) solutions mimicking tropospheric
aerosols. Secondary organic products were identified using Aerosol Chemical
Ionization Mass Spectrometry (Aerosol-CIMS), and changes in surface tension
were monitored using pendant drop tensiometry. Hemiacetal oligomers and aldol
condensation products were identified using Aerosol-CIMS. Acetaldehyde
depresses surface tension to 65(\pm2) dyn/cm in pure water (a 10% surface
tension reduction from that of pure water) and 62(\pm1) dyn/cm in AS solutions
(a 20.6% reduction from that of a 3.1 M AS solution). Surface tension
depression by formaldehyde in pure water is negligible; in AS solutions, a 9%
reduction in surface tension is observed. Mixtures of these species were also
studied in combination with methylglyoxal in order to evaluate the influence of
cross-reactions on surface tension depression and product formation in these
systems. We find that surface tension depression in the solutions containing
mixed cVOCs exceeds that predicted by an additive model based on the
single-species isotherms.Comment: Published in Atmospheric Chemistry and Physics 22 November 201
Few-Body Systems Composed of Heavy Quarks
Within the past ten years many new hadrons states were observed
experimentally, some of which do not fit into the conventional quark model. I
will talk about the few-body systems composed of heavy quarks, including the
charmonium-like states and some loosely bound states.Comment: Plenary talk at the 20th International IUPAP Conference on Few-Body
Problems in Physics, to appear in Few Body Systems (2013
Simulating Z_2 topological insulators with cold atoms in a one-dimensional optical lattice
We propose an experimental scheme to simulate and detect the properties of
time-reversal invariant topological insulators, using cold atoms trapped in
one-dimensional bichromatic optical lattices. This system is described by a
one-dimensional Aubry-Andre model with an additional SU(2) gauge structure,
which captures the essential properties of a two-dimensional Z2 topological
insulator. We demonstrate that topologically protected edge states, with
opposite spin orientations, can be pumped across the lattice by sweeping a
laser phase adiabatically. This process constitutes an elegant way to transfer
topologically protected quantum states in a highly controllable environment. We
discuss how density measurements could provide clear signatures of the
topological phases emanating from our one-dimensional system.Comment: 5 pages +, 3 figures, to appear in Physical Review
Gamma-Ray Burst Environments and Progenitors
Likely progenitors for the GRBs (gamma-ray bursts) are the mergers of compact
objects or the explosions of massive stars. These two cases have distinctive
environments for the GRB afterglow: the compact object explosions occur in the
ISM (interstellar medium) and those of massive stars occur in the preburst
stellar wind. We calculate the expected afterglow for a burst in a Wolf-Rayet
star wind and compare the results to those for constant, interstellar density.
The optical afterglow for the wind case is generally expected to decline more
steeply than in the constant density case, but this effect may be masked by
variations in electron spectral index, and the two cases have the same
evolution in the cooling regime. Observations of the concurrent radio and
optical/X-ray evolution are especially useful for distinguishing between the
two cases. The different rates of decline of the optical and X-ray afterglows
of GRB 990123 suggest constant density interaction for this case. We have
previously found strong evidence for wind interaction in SN 1998bw/GRB 980425
and here present a wind model for GRB 980519. We thus suggest that there are
both wind type GRB afterglows with massive star progenitors and ISM type
afterglows with compact binary star progenitors. The wind type bursts are
likely to be accompanied by a supernova, but not the ISM type.Comment: 11 pages, 1 figure, revised version, ApJ Letters, in pres
Conductance oscillation and quantization in monoatomic Al wires
We present first-principles calculations for the transport properties of
monoatomic Al wires sandwiched between Al(100) electrodes. The conductance of
the monoatomic Al wires oscillates with the number of the constituent atoms as
a function of the wire length, either with a period of four-atom for wires with
the typical interatomic spacing or a period of six-atom with the interatomic
spacing of the bulk fcc aluminum, indicating a dependence of the period of
conductance oscillation on the interatomic distance of the monoatomic Al wires
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