2,419 research outputs found
Nonlinear optics in Xe-filled hollow-core PCF in high pressure and supercritical regimes
Supercritical Xe at 293 K offers a Kerr nonlinearity that can exceed that of
fused silica while being free of Raman scattering. It also has a much higher
optical damage threshold and a transparency window that extends from the UV to
the infrared. We report the observation of nonlinear phenomena, such as
self-phase modulation, in hollow-core photonic crystal fiber filled with
supercritical Xe. In the subcritical regime, intermodal four-wave-mixing
resulted in the generation of UV light in the HE12 mode. The normal dispersion
of the fiber at high pressures means that spectral broadening can clearly
obtained without influence from soliton effects or material damage
Near-ionization-threshold emission in atomic gases driven by intense sub-cycle pulses
We study theoretically the dipole radiation of a hydrogen atom driven by an
intense sub-cycle pulse. The time-dependent Schr\"odinger equation for the
system is solved by ab initio calculation to obtain the dipole response.
Remarkably, a narrowband emission lasting longer than the driving pulse appears
at a frequency just above the ionization threshold. An additional calculation
using the strong field approximation also recovers this emission, which
suggests that it corresponds to the oscillation of nearly-bound electrons that
behave similarly to Rydberg electrons. The predicted phenomenon is unique to
ultrashort driving pulses but not specific to any particular atomic structure.Comment: 8 pages, 2 figure
Continuously wavelength-tunable high harmonic generation via soliton dynamics
We report generation of high harmonics in a gas-jet pumped by pulses
self-compressed in a He-filled hollow-core photonic crystal fiber through the
soliton effect. The gas-jet is placed directly at the fiber output. As the
energy increases the ionization-induced soliton blue-shift is transferred to
the high harmonics, leading to a emission bands that are continuously tunable
from 17 to 45 eV
Diet-induced obesity impairs mammary development and lactogenesis in murine mammary gland
We have developed a mouse model of diet-induced obesity that shows numerous abnormalities relating to mammary gland function. Animals ate 40% more calories when offered a high-fat diet and gained weight at three times the rate of controls. They exhibited reduced conception rates, increased peripartum pup mortality, and impaired lactogenesis. The impairment of lactogenesis involved lipid accumulation in the secretory epithelial cells indicative of an absence of copius milk secretion. Expression of mRNAs for -casein, whey acid protein, and -lactalbumin were all decreased immediately postpartum but recovered as lactation was established over 2–3 days. Expression of acetyl-CoA carboxylase (ACC)- mRNA was also decreased at parturition as was the total enzyme activity, although there was a compensatory increase in the proportion in the active state. By day 10 of lactation, the proportion of ACC in the active state was also decreased in obese animals, indicative of suppression of de novo fatty acid synthesis resulting from the supply of preformed fatty acids in the diet. Although obese animals consumed more calories in the nonpregnant and early pregnant states, they showed a marked depression in fat intake around day 9 of pregnancy before food intake recovered in later pregnancy. Food intake increased dramatically in both lean and obese animals during lactation although total calories consumed were identical in both groups. Thus, despite access to high-energy diets, the obese animals mobilized even more adipose tissue during lactation than their lean counterparts. Obese animals also exhibited marked abnormalities in alveolar development of the mammary gland, which may partially explain the delay in differentiation evident during lactogenesis
Supercontinuum generation in the vacuum ultraviolet through dispersive-wave and soliton-plasma interaction in noble-gas-filled hollow-core photonic crystal fiber
We report on the generation of a three-octave-wide supercontinuum extending
from the vacuum ultraviolet (VUV) to the near-infrared, spanning at least 113
to 1000 nm (i.e., 11 to 1.2 eV), in He-filled hollow-core kagome-style photonic
crystal fiber. Numerical simulations confirm that the main mechanism is a novel
and previously undiscovered interaction between dispersive-wave emission and
plasma-induced blueshifted soliton recompression around the fiber zero
dispersion frequency. The VUV part of the supercontinuum, which modeling shows
to be coherent and possess a simple phase structure, has sufficient bandwidth
to support single-cycle pulses of 500 attosecond duration. We also demonstrate,
in the same system, the generation of narrower-band VUV pulses, through
dispersive-wave emission, tunable from 120 to 200 nm with efficiencies
exceeding 1% and VUV pulse energies in excess of 50 nJ.Comment: 7 pages, 5 figure
The eventual leadership in dynamic mobile networking environments
2007-2008 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe
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