422 research outputs found
Rydberg Atom Sensors in Multichromatic Radio Frequency Fields
Rydberg atom-based sensors are a new type of radio frequency sensor that is
inherently quantum mechanical. Several configurations of the sensor use a local
oscillator to determine the properties of the target radio frequency field. We
explain how the physics of Rydberg atom-based sensors in two or more radio
frequency fields can be precisely described by a multiply dressed
Jaynes-Cummings model. Studying Rydberg atom-based sensors in two or more near
resonant radio frequency fields is important for understanding how interfering
signals as well as the local oscillator can affect measurements. Studies, so
far, focus on a simplified approximation for the local oscillator-target field
interaction that uses an analogy to radio frequency heterodyning. The atom acts
as a medium for exchanging electromagnetic field excitations of the field modes
whose spectrum is a ladder. The Jaynes-Cummings states and their avoided
crossings can be used to determine the properties of the radio frequency
fields. Radio frequency field sensitivity enhancement for non-resonant radio
frequencies is achieved and self-calibrated measurements are recovered under
specific conditions described by the theory
Satellite cell proliferation in adult skeletal muscle
Novel methods of retroviral-mediated gene transfer for the in vivo corporation and stable expression of eukaryotic or prokaryotic foreign genes in tissues of living animals is described. More specifically, methods of incorporating foreign genes into mitotically active cells are disclosed. The constitutive and stable expression of E. coli .beta.-galactosidase gene under the promoter control of the Moloney murine leukemia virus long terminal repeat is employed as a particularly preferred embodiment, by way of example, establishes the model upon which the incorporation of a foreign gene into a mitotically-active living eukaryotic tissue is based. Use of the described methods in therapeutic treatments for genetic diseases, such as those muscular degenerative diseases, is also presented. In muscle tissue, the described processes result in genetically-altered satellite cells which proliferate daughter myoblasts which preferentially fuse to form a single undamaged muscle fiber replacing damaged muscle tissue in a treated animal. The retroviral vector, by way of example, includes a dystrophin gene construct for use in treating muscular dystrophy. The present invention also comprises an experimental model utilizable in the study of the physiological regulation of skeletal muscle gene expression in intact animals
Extrahepatic tissue concentrations of vitamin K are lower in rats fed a high vitamin E diet
BACKGROUND: An adverse hematological interaction between vitamins E and K has been reported, primarily in patients on anticoagulants. However, little is known regarding circulating levels or tissue concentrations of vitamin K in response to vitamin E supplementation. The purpose of this study was to examine the effect of different levels of dietary ι-tocopherol on phylloquinone and menaquinone-4 concentrations, while maintaining a constant intake of phylloquinone, in rat tissues. METHODS: Male 4-wk old Fischer 344 rats (n = 33) were fed one of 3 diets for 12 wk: control (n = 13) with 30 mg all-rac-ι-tocopherol acetate/kg diet; vitamin E-supplemented (n = 10) with 100 mg all-rac-ι-tocopherol acetate/kg diet; and vitamin E-restricted (n = 10) with <10 mg total tocopherols/kg diet. All 3 diets contained 470 ¹ 80 Οg phylloquinone/kg diet. RESULTS: Phylloquinone concentrations were lower (P ⤠0.05) in the vitamin E-supplemented compared to the vitamin E-restricted group (mean ¹ SD spleen: 531 ¹ 58 vs.735 ¹ 77; kidney: 20 ¹ 17 vs. 94 ¹ 31, brain: 53 ¹ 19 vs.136 ¹ 97 pmol/g protein respectively); no statistically significant differences between groups were found in plasma, liver or testis. Similar results were noted with menaquinone-4 concentrations in response to vitamin E supplementation. CONCLUSION: There appears to be a tissue-specific interaction between vitamins E and K when vitamin E is supplemented in rat diets. Future research is required to elucidate the mechanism for this nutrient-nutrient interaction
Implementing an electronic sideband offset lock for precision spectroscopy in radium
We demonstrate laser frequency stabilization with at least 6 GHz of offset
tunability using an in-phase/quadrature (IQ) modulator to generate electronic
sidebands (ESB) on a titanium sapphire laser at 714 nm and we apply this
technique to the precision spectroscopy of Ra, and Ra. By
locking the laser to a single resonance of a high finesse optical cavity and
adjusting the lock offset, we determine the frequency difference between the
magneto-optical trap (MOT) transitions in the two isotopes to be
MHz, a factor of 29 more precise than the previously available data. Using the
known value of the hyperfine splitting of the level, we calculate
the isotope shift for the to transition to be
MHz, which is a factor of 8 more precise than the best available
value. Our technique could be applied to countless other atomic systems to
provide unprecedented precision in isotope shift spectroscopy and other
relative frequency comparisons
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data V. Hobby-Eberly Telescope Observations
We report the discovery of 27 quasars with redshifts between 3.58 and 4.49.
The objects were identified as high-redshift candidates based on their colors
in Sloan Digital Sky Survey commissioning data. The redshifts were confirmed
with low resolution spectra obtained at the Hobby-Eberly Telescope. The
quasars' magnitudes range from 18.55 to 20.97. Nearly 60% of the quasar
candidates observed are confirmed spectroscopically as quasars. Two of the
objects are Broad Absorption Line quasars, and several other quasars appear to
have narrow associated absorption features.Comment: 20 pages, 4 figures, AJ accepte
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Standalone vertex ďŹnding in the ATLAS muon spectrometer
A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at âs = 7 TeV collected with the ATLAS detector at the LHC during 2011
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