12,982 research outputs found
‘‘Lozenge’’ contour plots in scattering from polymer networks
We present a consistent explanation for the appearance of “lozenge” shapes in contour plots of the two dimensional scattering intensity from stretched polymer networks. By explicitly averaging over quenched variables in a tube model, we show that lozenge patterns arise as a result of chain material that is not directly deformed by the stretch. We obtain excellent agreement with experimental data
The [CII] 158 um Line Deficit in Ultraluminous Infrared Galaxies Revisited
We present a study of the [CII] 157.74 um fine-structure line in a sample of
15 ultraluminous infrared (IR) galaxies (L_IR>10^12 Lsun; ULIRGs) using the
Long Wavelength Spectrometer (LWS) on the Infrared Space Observatory (ISO). We
confirm the observed order of magnitude deficit (compared to normal and
starburst galaxies) in the strength of the [CII] line relative to the far-IR
dust continuum emission found in our initial report (Luhman et al. 1998), but
here with a sample that is twice as large. This result suggests that the
deficit is a general phenomenon affecting 4/5 ULIRGs. We present an analysis
using observations of generally acknowledged photodissociation region (PDR)
tracers ([CII], [OI] 63 and 145 um, and FIR continuum emission), which suggests
that a high UV flux G_o incident on a moderate density n PDR could explain the
deficit. However, comparisons with other ULIRG observations, including CO
(1-0), [CI] (1-0), and 6.2 um polycyclic aromatic hydrocarbon (PAH) emission,
suggest that high G_o/n PDRs alone cannot produce a self-consistent solution
that is compatible with all of the observations. We propose that non-PDR
contributions to the FIR continuum can explain the apparent [CII] deficiency.
Here, unusually high G_o and/or n physical conditions in ULIRGs as compared to
those in normal and starburst galaxies are not required to explain the [CII]
deficit. Dust-bounded photoionization regions, which generate much of the FIR
emission but do not contribute significant [CII] emission, offer one possible
physical origin for this additional non-PDR component. Such environments may
also contribute to the observed suppression of FIR fine-structure emission from
ionized gas and PAHs, as well as the warmer FIR colors found in ULIRGs. The
implications for observations at higher redshifts are also revisited.Comment: to be published in The Astrophysical Journal, 58 page
Quantum Optical Systems for the Implementation of Quantum Information Processing
We review the field of Quantum Optical Information from elementary
considerations through to quantum computation schemes. We illustrate our
discussion with descriptions of experimental demonstrations of key
communication and processing tasks from the last decade and also look forward
to the key results likely in the next decade. We examine both discrete (single
photon) type processing as well as those which employ continuous variable
manipulations. The mathematical formalism is kept to the minimum needed to
understand the key theoretical and experimental results
Psychological Flexibility, ACT, and Organizational Behavior
This paper offers organizational behavior management (OBM) a behavior analytically consistent way to expand its analysis of, and methods for changing, organizational behavior. It shows how Relational Frame Theory (RFT) suggests that common, problematic, psychological processes emerge from language itself, and they produce psychological inflexibility. Research suggests that an applied extension of RFT, Acceptance and Commitment Therapy, has led to new interventions that increase psychological flexibility and, thereby enhance, organizational behavior and health
Motional effects on the efficiency of excitation transfer
Energy transfer plays a vital role in many natural and technological
processes. In this work, we study the effects of mechanical motion on the
excitation transfer through a chain of interacting molecules with application
to biological scenarios of transfer processes. Our investigation demonstrates
that, for various types of mechanical oscillations, the transfer efficiency is
significantly enhanced over that of comparable static configurations. This
enhancement is a genuine quantum signature, and requires the collaborative
interplay between the quantum-coherent evolution of the excitation and the
mechanical motion of the molecules; it has no analogue in the classical
incoherent energy transfer. This effect may not only occur naturally, but it
could be exploited in artificially designed systems to optimize transport
processes. As an application, we discuss a simple and hence robust control
technique.Comment: 25 pages, 11 figures; completely revised; version accepted for
publicatio
Local structure and site occupancy of Cd and Hg substitutions in CeTIn5 (T=Co, Rh, Ir)
The CeTIn5 superconductors (T=Co, Rh, or Ir) have generated great interest
due to their relatively Tc's, NFL behavior, and their proximity to AF order and
quantum critical points. In contrast to small changes with the T-species,
electron doping in CeT(In{1-x}Mx)5 with M=Sn and hole doping with Cd or Hg have
a dramatic effect on the electronic properties at very low concentrations. The
present work reports EXAFS measurements that address the substituent atom
distribution as a function of T, M, and x, near the superconducting phase.
Together with previous measurements for M=Sn, the proportion of the M atom
residing on the In(1) site, f{In(1)}, increases in the order M=Cd, Sn, and Hg,
ranging from about 40% to 70%, showing a strong preference for these
substituents to occupy the In(1) site (random=20%). In addition, f{In(1)}
ranges from 70% to 100% for M=Hg in the order T=Co, Rh, and Ir. These fractions
track the changes in the atomic radii of the various species, and help explain
the sharp dependence of Tc on substituting into the In site. However, it is
difficult to reconcile the small concentrations of M with the dramatic changes
in the ground state in the hole-doped materials with only an impurity
scattering model. These results therefore indicate that while such
substitutions have interesting local atomic structures with important
electronic and magnetic consequences, other local changes in the electronic and
magnetic structure are equally important in determining the bulk properties of
these materials.Comment: 10 pages, 7 figures, to appear in PR
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