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1.
Phys Rev Lett ; 126(19): 197701, 2021 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-34047614

RESUMO

Spontaneous decay of a single photon is a notoriously inefficient process in nature irrespective of the frequency range. We report that a quantum phase-slip fluctuation in high-impedance superconducting waveguides can split a single incident microwave photon into a large number of lower-energy photons with a near unit probability. The underlying inelastic photon-photon interaction has no analogs in nonlinear optics. Instead, the measured decay rates are explained without adjustable parameters in the framework of a new model of a quantum impurity in a Luttinger liquid. Our result connects circuit quantum electrodynamics to critical phenomena in two-dimensional boundary quantum field theories, important in the physics of strongly correlated systems. The photon lifetime data represent a rare example of verified and useful quantum many-body simulation.

2.
Science ; 279(5357): 1692-8, 1998 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-9497282

RESUMO

The Thermal Emission Spectrometer spectra of low albedo surface materials suggests that a four to one mixture of pyroxene to plagioclase, together with about a 35 percent dust component provides the best fit to the spectrum. Qualitative upper limits can be placed on the concentration of carbonates (<10 percent), olivine (<10 percent), clay minerals (<20 percent), and quartz (<5 percent) in the limited regions observed. Limb observations in the northern hemisphere reveal low-lying dust hazes and detached water-ice clouds at altitudes up to 55 kilometers. At an aerocentric longitude of 224 degrees a major dust storm developed in the Noachis Terra region. The south polar cap retreat was similar to that observed by Viking.


Assuntos
Meio Ambiente Extraterreno , Marte , Atmosfera , Dióxido de Carbono , Carbonatos , Gelo , Compostos de Ferro , Compostos de Magnésio , Minerais , Silicatos , Astronave , Análise Espectral , Temperatura , Água
3.
Biochim Biophys Acta ; 715(1): 52-6, 1982 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-7074132

RESUMO

Mössbauer spectroscopy was used to investigate the distribution of iron in rat organs and its localisation in liver subcellular fraction. A 57Fe-sucrose complex solution was injected by 0.5 ml doses into tail veins of animals every day, during a 6-day period. Mössbauer spectra were measured in spleen, blood, liver and liver subcellular fractions. The mössbauer spectrum of a spleen sample has two symmetrical doublets, one with delta = 0.6 mm/s and delta = 0.7 mm/s, and the other with delta = 1.0 mm/s and delta = 2.35 mm/s. The Mössbauer spectrum of blood has parameters which are close to those for carboxyhemoglobin and oxyhemoglobin complexes. After the addition of sodium citrate, the proportion of the carboxyhemoglobin complex increases. The Mössbauer spectrum of liver has a two-component pattern with two symmetrical doublets, the first with delta = 0.6 mm/s and delta = 0.63 mm/s and the second with delta = 1.4 mm/s and delta = 3.45 mm/s. The first component, which was identified as ferritin, is present in all subcellular fractions (800 x gav sediment fraction, mitochondrial/lysosomal, microsomal and supernatant fractions), with its greatest content in microsomal fraction. After the addition of NaBH4 to mitochondrial/lysosomal fraction, about 20% of the iron contained in ferritin was reduced. In the Mössbauer spectrum this is reflected by an appearance of a doublet with delta = 0.85 mm/s and delta = 3.7 mm/s.


Assuntos
Ferro/metabolismo , Fígado/metabolismo , Animais , Radioisótopos de Ferro , Masculino , Ratos , Análise Espectral , Baço/metabolismo , Frações Subcelulares/metabolismo , Sacarose
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