269 research outputs found
Determination of dimethoxyphenethylamine derivatives in urine by deuterium labeled internal standards
The use of gas chromatography–mass spectrometry (GC–MS) in forensic analysis is increasing. To exploit fully the capabilities of MS, labeled standards, that can be used to improve the performance of the quantitative analysis, and to increase accuracy and precision, are required. A series of deuterated internal standards, corresponding to the 2C-series of phenethylamine derivatives, including 4-bromo-2,5-dimethoxyphenethylamine-d6 (2C-B), 4-chloro-2,5-dimethoxyphenethylamine-d6 (2C-C), 4-iodo-2,5-dimethoxy-phe¬nethyl-amine-d6 (2C-I), 4-ethylthio-2,5-dimethoxy-phenethylamine-d6 (2C-T-2) and 2,5-dimethoxy-4-n-propylthiophenethylamine-d6 (2C-T-7), were synthesized. These deuterated compounds were used to analyze for the corresponding unlabeled compounds in urine. The analysis was performed using GC–MS, with the selected ion monitoring (SIM) technique, whereby good results were achieved
Fragmentation and OB Star Formation in High-Mass Molecular Hub-Filament System
Filamentary structures are ubiquitously seen in the interstellar medium. The
concentrated molecular mass in the filaments allows fragmentation to occur in a
shorter timescale than the timescale of the global collapse. Such hierarchical
fragmentation may further assist the dissipation of excessive angular momentum.
It is crucial to resolve the morphology and the internal velocity structures of
the molecular filaments observationally.
We perform 0".5-2".5 angular resolution interferometric observations toward
the nearly face-on OB cluster forming region G33.92+0.11. Observations of
various spectral lines as well as the millimeter dust continuum emission,
consistently trace several 1 pc scale, clumpy molecular arms. Some of the
molecular arms geometrically merge to an inner
3.0\,, 0.6
pc scale central molecular clump, and may directly channel the molecular gas to
the warm (50 K) molecular gas immediately surrounding the centrally
embedded OB stars. The NH spectra suggest a medium turbulence line width
of FWHM2\,km\,s in the central molecular clump, implying a
10 times larger molecular mass than the virial mass. Feedbacks from
shocks and the centrally embedded OB stars and localized (proto)stellar
clusters, likely play a key role in the heating of molecular gas and could lead
to the observed chemical stratification. Although (proto)stellar feedbacks are
already present, G33.92+0.11 chemically appears to be at an early evolutionary
stage given by the low abundance limit of SO observed in this region.Comment: 37 pages, 23 figure
The Outflow from the Luminous Young Stellar Object IRAS 20126+4104: From 4000 AU to 0.4 pc
We have imaged the outflow from the luminous young stellar object IRAS 20126+4104 (I20126) with the Submillimeter Array in CO (3-2), HCN (4-3), and SiO (5-4) at 1''-2'' resolutions within a radius of ~20'' from the central driving source. Our observations reveal at least three different components of the outflowing gas: (1) A compact (~4000 AU) bipolar outflow toward the central young stellar object. With a dynamical timescale of ~120 yr, this component represents a very new jet/outflow activity in I20126. (2) A collimated outflow with an extent of ~0.2 pc previously detected in SiO (2-1). Both morphology and kinematics favor this component being a jet-driven bow shock system. (3) An S-shaped CO outflow with an extent of ~0.4 pc. This component records the precession history very well. Its kinematic feature, where the velocity increases with distance from the YSO, indicates, independently of other evidence, that the outflow axis is moving toward the plane of the sky. The three outflow components record the history of the primary jet precession over scales ranging from a few hundred AU to approximately 0.4 pc. Our results indicate that CO (3-2) emission is a good tracer to probe the primary jet. The gas densities and SiO relative abundances in I20126 shocks are estimated using the large velocity gradient calculations. The inferred SiO abundances of (1-5) × 10-8 in I20126 outflow lobes are comparable to the expected enhancement at shocked regions
The Hot and Clumpy Molecular Cocoon Surrounding the Ultracompact HII Region G5.89-0.39
We present observations of CH3CN (12-11) emission at a resolution of 2"
toward the shell-like ultracompact HII region G5.89-0.39 with the Submillimeter
Array. The integrated CH3CN emission reveals dense and hot molecular cocoon in
the periphery of the HII region G5.89-0.39, with a CH3CN deficient region
roughly centered at G5.89-0.39. By analyzing the CH3CN emission using
population diagram analysis, we find, for the first time, a decreasing
temperature structure from 150 to 40 K with the projected distance from Feldt's
star, which is thought to be responsible for powering the HII region. Our
results further indicate that the majority of the heating energy in the
observed dense gas is supplied by the Feldt's star. From the derived CH3CN
column density profile, we conclude that the dense gas is not
uniformly-distributed but centrally-concentrated, with a power-law exponent of
5.5 for r < 8000 AU, and 2.0 for 8000 AU < r < 20000 AU, where r is the
distance to Feldt's star. The estimated large power index of 5.5 can be
attributed to an enhancement of CH3CN abundance in the close vicinity of
Feldt's star.Comment: accepted for publication in The Astrophysical Journal Letter
Projection of Supply and Demand of the Physical Therapy Manpower in Taiwan for the Next Twenty Years: Part I. Current Status and Productivity of Physical Therapists and Physical Therapist Assistants
Background and purposes: The purposes of this study were 1) to describe the general productivity and productivities in 4 special fields (neurological, orthopedic, pediatric, and cardiopulmonary) of physical therapists (PT) and physical therapist assistants (PTA) in Taiwan, and 2) to explore the association between characteristics of PT/PTA and productivity.
Method: Questionnaire was mailed to the members of all PT and PTA associations in Taiwan. The total mailing number of questionnaire for PT and PTA were 2466 and 1117, respectively. The content of this questionnaire included basic demographic data and information in clinical work. Survey period was between September, 2002 and December, 2002.
Results: Total returned questionnaires were 764 from PT and 269 from PTA. General productivity for aPT was 21.39 patients per day, assuming working 8 hours per day. For each specialization field, the productivity of neurological, orthopedic, pediatric, cardiop ulmonary patients of each PT per day was 19.72 (sd=9.50), 24.98 (sd=11.07), 15.55 (sd=8.75), and 21.42 (sd=10.63), respectively. For the association between PT characteristics and productivity, working place and PT\u27 s gender were significantly associated with general productivity. PT\u27s age, educational level, and working place were significantly associated with neurological and pediatric productivities. Working experience was also significantly associated with neurological productivity. PT\u27 s characteristics were not significantly associated with orthopedic and cardiopulmonary productivity. General productivity for a PTA was 29.75 patients per day. The productivity of neurological, orthopedic, pediatric, cardiopulmonary patients of each PTA per day was 22.29 (sd=9.50), 35.07 (sd=11.07), 19.48 (sd=8.75), and 19.55 (sd=10.63), respectively. Only PTA\u27s education level was significantly associated with orthopedic productivity. There were no other significant associations between any of the PTA\u27s characteristics and productivity.
Conclusion: This study repported the current status of clincial practice in PT and PTA. There will be a series of articles investigating the projection of supply and demand of physical therapy manpower for the next twenty years
A High-Mass Protobinary System in the Hot Core W3(H2O)
We have observed a high-mass protobinary system in the hot core W3(H2O) with
the BIMA Array. Our continuum maps at wavelengths of 1.4mm and 2.8mm both
achieve sub-arcsecond angular resolutions and show a double-peaked morphology.
The angular separation of the two sources is 1.19" corresponding to 2.43X10^3
AU at the source distance of 2.04 kpc. The flux densities of the two sources at
1.4mm and 2.8mm have a spectral index of 3, translating to an opacity law of
kappa ~ nu. The small spectral indices suggest that grain growth has begun in
the hot core. We have also observed 5 K components of the CH3CN (12-11)
transitions. A radial velocity difference of 2.81 km/s is found towards the two
continuum peaks. Interpreting these two sources as binary components in orbit
about one another, we find a minimum mass of 22 Msun for the system. Radiative
transfer models are constructed to explain both the continuum and methyl
cyanide line observations of each source. Power-law distributions of both
density and temperature are derived. Density distributions close to the
free-fall value, r^-1.5, are found for both components, suggesting continuing
accretion. The derived luminosities suggest the two sources have equivalent
zero-age main sequence (ZAMS) spectral type B0.5 - B0. The nebular masses
derived from the continuum observations are about 5 Msun for source A and 4
Msun for source C. A velocity gradient previously detected may be explained by
unresolved binary rotation with a small velocity difference.Comment: 38 pages, 9 figures, accepted by The Astrophysical Journa
Submillimeter Array Observations of the Molecular Outflow in High-mass Star-forming Region G240.31+0.07
We present Submillimeter Array observations toward the 10^{4.7} Lsun
star-forming region G240.31+0.07, in the J=2-1 transition of 12CO and 13CO and
at 1.3 mm continuum, as well as the 12CO and 13CO observations from the Caltech
Submillimeter Observatory to recover the extended emission filtered out by the
interferometer. Maps of the 12CO and 13CO emission show a bipolar, wide-angle,
quasi-parabolic molecular outflow, roughly coincident with an IR nebula
revealed by the Spitzer 3.6 and 4.5 micron emission. The outflow has ~98 Msun
molecular gas, making it one of the most massive molecular outflows known, and
resulting in a very high mass-loss rate of 4.1 by 10^{-3} Msun yr^{-1} over a
dynamical timescale of 2.4 by 10^4 yr. The 1.3 mm continuum observations with a
4" by 3" beam reveal a flattened dusty envelope of ~150 Msun, which is further
resolved with a 1.2" by 1" beam into three dense cores with a total mass of ~40
Msun. The central mm core, showing evidence of active star formation,
approximately coincides with the geometric center of the bipolar outflow thus
most likely harbors the powering source of the outflow. Overall our
observations provide the best case to date of a well-defined wide-angle
molecular outflow in a >10^4 Lsun star-forming region. The outflow is
morphologically and kinematically similar to low-mass protostellar outflows but
has two to three orders of magnitude greater mass, momentum, and energy, and is
apparently driven by an underlying wide-angle wind, hence further supports that
high-mass stars up to late-O types, even in a crowded clustering environment,
can form as a scaled-up version of low-mass star formation.Comment: accepted for publication in the Ap
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