876 research outputs found
Thermal light cannot be represented as a statistical mixture of single pulses
We ask whether or not thermal light can be represented as a mixture of single
broadband coherent pulses. We find that it cannot. Such a mixture is simply not
rich enough to mimic thermal light; indeed, it cannot even reproduce the
first-order correlation function. We show that it is possible to construct a
modified mixture of single coherent pulses that does yield the correct
first-order correlation function at equal space points. However, as we then
demonstrate, such a mixture cannot reproduce the second-order correlation
function.Comment: 5 pages, 2 figures. Published versio
Cytokine Reduction in the Treatment of Joint Conditions
The destruction of joints caused by rheumatoid arthritis and
osteoarthritis is characterized by an imbalance of enzyme catalysed
cartilage breakdown and regeneration. A complex cytokine network
perpetuates joint conditions by direct regulation of
metalloproteases, by indirect recruitment of cells that secrete
degradative enzymes, and by inhibition of reparative processes. The
destructive action of cytokines such as interleukin-1, interleukin-6
and tumour necrosis factor-α can be modulated at multiple
points associated either with cytokine production or with cytokine
action. Potential agents for cytokine reduction include selective
anti-cytokine antibodies, anticytokine receptor antibodies, cytokine
receptor antagonist proteins, and soluble and chimeric cytokine
receptor molecules. Pharmacologic regulation of IL-1 and TNFα
remain primary targets for treatment of arthritis, and results of
early clinical trials are promising. However, the results of
long-term clinical trials will be required to support the value of
anti-cytokine therapy in treatment of arthritis
Second and Third Harmonic Generation in Metal-Based Nanostructures
We present a new theoretical approach to the study of second and third
harmonic generation from metallic nanostructures and nanocavities filled with a
nonlinear material, in the ultrashort pulse regime. We model the metal as a
two-component medium, using the hydrodynamic model to describe free electrons,
and Lorentz oscillators to account for core electron contributions to both the
linear dielectric constant and to harmonic generation. The active nonlinear
medium that may fill a metallic nanocavity, or be positioned between metallic
layers in a stack, is also modeled using Lorentz oscillators and surface
phenomena due to symmetry breaking are taken into account. We study the effects
of incident TE- and TM-polarized fields and show that a simple re-examination
of the basic equations reveals additional exploitable dynamical features of
nonlinear frequency conversion in plasmonic nanostructures.Comment: 33 pages, including 11 figures and 74 references; corrected
affiliations and some typo
Nonlinear Bloch-wave interaction and Bragg scattering in optically-induced lattices
We study, both theoretically and experimentally, the Bragg scattering of
light in optically-induced photonic lattices and reveal the key physical
mechanisms which govern nonlinear self-action of narrow beams under the
combined effects of Bragg scattering and wave diffraction, allowing for
selecting bands with different effective dispersion.Comment: 4 pages, 6 figure
Generation of spin currents via Raman scattering
We show theoretically that stimulated spin flip Raman scattering can be used
to inject spin currents in doped semiconductors with spin split bands. A pure
spin current, where oppositely oriented spins move in opposite directions, can
be injected in zincblende crystals and structures. The calculated spin current
should be detectable by pump-probe optical spectroscopy and anomalous Hall
effect measurement
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