4,992 research outputs found

    Observations of time delayed all-optical routing in a slow light regime

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    We report an observation of a delayed all-optical routing/switching phenomenon based on ultraslow group velocity of light via nondegenerate four-wave mixing processes in a defected solid medium. Unlike previous demonstrations of enhanced four-wave mixing processes using the slow light effects, the present observation demonstrates a direct retrieval of the resonant Raman-pulse excited spin coherence into photon coherence through coherence conversion processes.Comment: 5 pages with 3 figures include

    The physical and chemical properties of human sweat and factors affecting the water balance in confined spaces Final report, 1 Jul. 1965 - 30 Jun. 1968

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    Physical and chemical properties of human sweat and factors affecting water balance in confined space

    The Physical and Chemical Properties of Human Sweat and Factors Affecting the Water Balance in Confined Spaces Semiannual Status Report No. 2, 1 Jan. - 30 Jun. 1966

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    Physical and chemical properties of human sweat and factors affecting water balance in confined space

    Jaynes-Cummings dynamics with a matter wave oscillator

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    We propose to subject two Bose-Einstein condensates to a periodic potential, so that one condensate undergoes the Mott insulator transition to a state with precisely one atom per lattice site. We show that photoassociation of heteronuclear molecules within each lattice site is described by the quantum optical Jaynes-Cummings Hamiltonian. In analogy with studies of this Hamiltonian with cavity fields and trapped ions, we are thus able to engineer quantum optical states of atomic matter wave fields and we are able to reconstruct these states by quantum state tomography.Comment: 4 pages, 2 figure

    Chemistry in circumstellar disks: CS toward HL Tauri

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    High-resolution millimeter-wave aperture synthesis images of the CS J = 2 → 1 and dust continuum emission toward the young star HL Tauri have been combined with single-dish spectra of the higher J CS transitions in order to probe the chemical and physical structure of circumstellar material in this source. We find that the extended molecular cloud surrounding HL Tau is similar to other Taurus dark cloud cores, having T_(kinetic) ≈ 10-20 K, n_(H2) ≈ 10^4-10^5 cm^(-3) , and x(CS) = N(CS)/N(H_2) ≈ (1-2) x 10^(-8). In contrast, the gas-phase CS abundance in the circumstellar disk is depleted by factors of at least 25-50, and perhaps considerably more. These results are consistent with substantial depletion onto grains, or a transition from kinetically controlled chemistry in the molecular cloud to thermodynamically controlled chemistry in the outer regions of the circumstellar disk. Dust continuum emission at 3.06 mm, although unresolved in a 3".0 beam, appears centered on the stellar position; combined with other millimeter-wave measurements its intensity indicates an emissivity index of β = 1.2 ± 0.3. This β may reflect grain growth via depletion and aggregation or compositional evolution, and suggests that the 3.06 mm dust opacity exceeds unity within 8-10 AU of HL Tauri. Even at millimeter and submillimeter wavelengths, observational studies of other high dipole moment molecules in circumstellar disks may also be hampered by the combination of grain mantle depletion and dust opacity structure in sources viewed nearly edge-on

    Shatter cones in Illinois: Evidence for metoeritic impacts at Glasford and Des Plaines

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    Shatter cone fragments were recovered from rock cores at two previously suspected, but heretofore unverified, impact structures in Illinois. Both sites are buried features known from geophysical surveys and drill holes. Shatter cones are accepted widely as field criteria of meteoritic impact. Detection of these shock indicators in both the Glasford Structure and the Des Plains Disturbance upgrades these sites in Earth's inventory of known and suspected impact structures from possible impact sites with compatible structure and morphology to probable impact structures which possess also evidence of shock metamorphism
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