1,115 research outputs found
Excitation and emission spectra of rubidium in rare-gas thin-films
To understand the optical properties of atoms in solid state matrices, the
absorption, excitation and emission spectra of rubidium doped thin-films of
argon, krypton and xenon were investigated in detail. A two-dimensional
spectral analysis extends earlier reports on the excitation and emission
properties of rubidium in rare-gas hosts. We found that the doped crystals of
krypton and xenon exhibit a simple absorption-emission relation, whereas
rubidium in argon showed more complicated spectral structures. Our sample
preparation employed in the present work yielded different results for the Ar
crystal, but our peak positions were consistent with the prediction based on
the linear extrapolation of Xe and Kr data. We also observed a bleaching
behavior in rubidium excitation spectra, which suggests a population transfer
from one to another spectral feature due to hole-burning. The observed optical
response implies that rubidium in rare-gas thin-films is detectable with
extremely high sensitivity, possibly down to a single atom level, in low
concentration samples.Comment: 7 pages, 5 figure
Relative Evolutionary Time Scale of Hot Molecular Cores with Respect to Ultra Compact HII Regions
Using the Owens Valley and Nobeyama Radio Observatory interferometers, we
carried out an unbiased search for hot molecular cores and ultracompact UC HII
regions toward the high-mass star forming region G19.61--0.23. In addition, we
performed 1.2 mm imaging with SIMBA, and retrieved 3.5 and 2 cm images from the
VLA archive data base. The newly obtained 3 mm image brings information on a
cluster of high-mass (proto)stars located in the innermost and densest part of
the parsec scale clump detected in the 1.2 mm continuum. We identify a total of
10 high-mass young stellar objects: one hot core (HC) and 9 UC HII regions,
whose physical parameters are obtained from model fits to their continuum
spectra. The ratio between the current and expected final radii of the UC \HII
regions ranges from 0.3 to 0.9, which leaves the possibility that all O-B stars
formed simultaneously. Under the opposite assumption -- namely that star
formation occurred randomly -- we estimate that HC lifetime is less than
1/3 of that of UCHII regions on the basis of the source number ratio
between them.Comment: 13 pages, 2 figs, including a color fi
A Water Maser and Ammonia Survey of GLIMPSE Extended Green Objects (EGOs)
We present the results of a Nobeyama 45-m water maser and ammonia survey of
all 94 northern GLIMPSE Extended Green Objects (EGOs), a sample of massive
young stellar objects (MYSOs) identified based on their extended 4.5 micron
emission. We observed the ammonia (1,1), (2,2), and (3,3) inversion lines, and
detect emission towards 97%, 63%, and 46% of our sample, respectively (median
rms ~50 mK). The water maser detection rate is 68% (median rms ~0.11 Jy). The
derived water maser and clump-scale gas properties are consistent with the
identification of EGOs as young MYSOs. To explore the degree of variation among
EGOs, we analyze subsamples defined based on MIR properties or maser
associations. Water masers and warm dense gas, as indicated by emission in the
higher-excitation ammonia transitions, are most frequently detected towards
EGOs also associated with both Class I and II methanol masers. 95% (81%) of
such EGOs are detected in water (ammonia(3,3)), compared to only 33% (7%) of
EGOs without either methanol maser type. As populations, EGOs associated with
Class I and/or II methanol masers have significantly higher ammonia linewidths,
column densities, and kinetic temperatures than EGOs undetected in methanol
maser surveys. However, we find no evidence for statistically significant
differences in water maser properties (such as maser luminosity) among any EGO
subsamples. Combining our data with the 1.1 mm continuum Bolocam Galactic Plane
Survey, we find no correlation between isotropic water maser luminosity and
clump number density. Water maser luminosity is weakly correlated with clump
(gas) temperature and clump mass.Comment: Astrophysical Journal, accepted. Emulateapj, 24 pages including 24
figures, plus 9 tables (including full content of online-only tables
Carpal tunnel pressure measurement during two-portal endoscopic carpal tunnel release
Background: Although there remain concerns of median nerve damage during endoscopic carpal tunnel release for carpal tunnel syndrome, carpal tunnel pressure variations during Chow's two-portal techinique have not been well investigated. Methods: We performed a modified two-portal endoscopic carpal tunnel release on 30 patients by inserting a catheter pressure transducer into the carpal tunnel for continuous pressure measurement during the procedure. Grip and pinch strengths, Semmes-Weinstein monofilament test, and nerve conduction studies were examined preoperatively and at postoperative 1, 3, and 6 months. Numbness and the Disabilities of the Arm, Shoulder and Hand score were also evaluated pre and postoperatively. Findings: Subjective symptoms and nerve conduction study findings improved uneventfully. The pressure was always observed to be maximum pressure immediately before the cannula was withdrawn from the exit portal, and carpal tunnel pressure >300 mm Hg was recorded in most of the patients. Interpretation: A transient increase in the carpal tunnel pressure occurred in all the patients; however, it did not correlate with their clinical outcome or with increased risk of pen-operative complications. Since time-pressure threshold of the median nerve during endoscopic carpal tunnel release is still unknown, our results did not guarantee its safety.ArticleCLINICAL BIOMECHANICS. 25(9):893-898 (2010)journal articl
Toward the beta-FeSi2 p-n homo-junction structure
ArticleTHIN SOLID FILMS. 515(22): 8210-8215 (2007)journal articl
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