525 research outputs found
A study on subarcsecond scales of the ammonia and continuum emission toward the G16.59-0.05 high-mass star-forming region
We wish to investigate the structure, velocity field, and stellar content of
the G16.59-0.05 high-mass star-forming region, where previous studies have
established the presence of two almost perpendicular (NE-SW and SE-NW), massive
outflows, and a rotating disk traced by methanol maser emission. We performed
Very Large Array observations of the radio continuum and ammonia line emission,
complemented by COMICS/Subaru and Hi-GAL/Herschel images in the mid- and
far-infrared (IR). Our centimeter continuum maps reveal a collimated radio jet
that is oriented E-W and centered on the methanol maser disk, placed at the SE
border of a compact molecular core. The spectral index of the jet is negative,
indicating non-thermal emission over most of the jet, except the peak close to
the maser disk, where thermal free-free emission is observed. We find that the
ammonia emission presents a bipolar structure consistent (on a smaller scale)
in direction and velocity with that of the NE-SW bipolar outflow detected in
previous CO observations. After analyzing our previous N2H+(1-0) observations
again, we conclude that two scenarios are possible. In one case both the radio
jet and the ammonia emission would trace the root of the large-scale CO bipolar
outflow. The different orientation of the jet and the ammonia flow could be
explained by precession and/or a non-isotropic density distribution around the
star. In the other case, the N2H+(1-0) and ammonia bipolarity is interpreted as
two overlapping clumps moving with different velocities along the line of
sight. The ammonia gas also seems to undergo rotation consistent with the maser
disk. Our IR images complemented by archival data allow us to derive a
bolometric luminosity of about 10^4 L_sun and to conclude that most of the
luminosity is due to the young stellar object associated with the maser disk.Comment: 11 pages, 12 figures, published in Astronomy and Astrophysic
Evolution and excitation conditions of outflows in high-mass star-forming regions
Theoretical models suggest that massive stars form via disk-mediated
accretion, with bipolar outflows playing a fundamental role. A recent study
toward massive molecular outflows has revealed a decrease of the SiO line
intensity as the object evolves. The present study aims at characterizing the
variation of the molecular outflow properties with time, and at studying the
SiO excitation conditions in outflows associated with massive YSOs. We used the
IRAM30m telescope to map 14 massive star-forming regions in the SiO(2-1),
SiO(5-4) and HCO+(1-0) outflow lines, and in several dense gas and hot core
tracers. Hi-GAL data was used to improve the spectral energy distributions and
the L/M ratio, which is believed to be a good indicator of the evolutionary
stage of the YSO. We detect SiO and HCO+ outflow emission in all the sources,
and bipolar structures in six of them. The outflow parameters are similar to
those found toward other massive YSOs. We find an increase of the HCO+ outflow
energetics as the object evolve, and a decrease of the SiO abundance with time,
from 10^(-8) to 10^(-9). The SiO(5-4) to (2-1) line ratio is found to be low at
the ambient gas velocity, and increases as we move to high velocities,
indicating that the excitation conditions of the SiO change with the velocity
of the gas (with larger densities and/or temperatures for the high-velocity gas
component). The properties of the SiO and HCO+ outflow emission suggest a
scenario in which SiO is largely enhanced in the first evolutionary stages,
probably due to strong shocks produced by the protostellar jet. As the object
evolves, the power of the jet would decrease and so does the SiO abundance.
During this process, however, the material surrounding the protostar would have
been been swept up by the jet, and the outflow activity, traced by entrained
molecular material (HCO+), would increase with time.Comment: 31 pages, 10 figures and 5 tables (plus 2 figures and 3 tables in the
appendix). Accepted for publication in A&A. [Abstract modified to fit the
arXiv requirements.
Trastuzumab beyond progression: a cost-utility analysis
Background: The continuation of trastuzumab beyond progression in combination with capecitabine as secondary chemotherapy for HER2-positive metastatic breast cancer (MBC) prolongs progression-free survival without a substantial increase in toxicity. Patients and methods: A Markov cohort simulation was used to follow the clinical course of typical patients with MBC. Information on response rates and major adverse effects was derived, and transition probabilities were estimated, based on the results of the Breast International Group 03-05 clinical trial. Direct costs were assessed from the perspective of the Swiss health care system. Results: The addition of trastuzumab to capecitabine is estimated to cost on average an additional of €33 980 and to yield a gain of 0.35 quality-adjusted life years (QALYs), resulting in an incremental cost-effectiveness ratio of €98 329/QALYs gained. Probabilistic sensitivity analysis showed that the willingness-to-pay threshold of €60 000/QALY was reached in 12% of cases. Conclusion: The addition of trastuzumab to capecitabine in MBC patients is more expensive than what is typically regarded as cost-effective but falls within the value ranges found for established regimens in the treatment of MB
NG7538 IRS1 N: modeling a circumstellar maser disk
We present an edge-on Keplerian disk model to explain the main component of
the 12.2 and 6.7 GHz methanol maser emission detected toward NGC7538-IRS1 N.
The brightness distribution and spectrum of the line of bright masers are
successfully modeled with high amplification of background radio continuum
emission along velocity coherent paths through a maser disk. The bend seen in
the position-velocity diagram is a characteristic signature of differentially
rotating disks. For a central mass of 30 solar masses, suggested by other
observations, our model fixes the masing disk to have inner and outer radii of
about 270 AU and 750 AU.Comment: To appear in The Proceedings of the 2004 European Workshop: "Dense
Molecular Gas around Protostars and in Galatic Nuclei", Eds. Y. Hagiwara,
W.A. Baan, H.J. van Langevelde, 2004, a special issue of ApSS, Kluwe
6.7 GHz methanol absorption toward the Seyfert 2 galaxy NGC 3079
The detection of the 6.7 GHz line of methanol (CH3OH) is reported for the
first time toward an object beyond the Magellanic Clouds. Using the Effelsberg
100 m telescope, two absorption features were identified toward the Seyfert 2
galaxy NGC 3079. Both components probably originated on lines-of-sight toward
the central region, presumably absorbing the radio continuum of the nuclear
sources A, B, and E of NGC 3079. One absorption feature, at the systemic
velocity, is narrow and may arise from gas not related to the nuclear
environment of the galaxy. The weaker blue-shifted component is wider and may
trace outflowing gas. Total A-type CH3OH column densities are estimated to be
between a few times 10^13 and a few times 10^15 cm^-2. Because of a highly
frequency-dependent continuum background, the overall similarity of HI, OH, and
CH3OH absorption profiles hints at molecular clouds that cover the entire area
occupied by the nuclear radio continuum sources ~ 4 pc.Comment: 4 pages, 1 figure, accepted for publication in A&A Letter
Temsirolimus Is Highly Effective as Third-Line Treatment in Chromophobe Renal Cell Cancer
We report unexpectedly high efficacy of temsirolimus as third-line treatment in a patient with metastatic chromophobe renal cell carcinoma. After failure of two sequentially administered tyrosine kinase inhibitors, treatment with temsirolimus resulted in a prolonged partial remission of 14 months, and the response is still continuing. Up to now, no data from randomized clinical studies have been published addressing the question of efficacy of temsirolimus as third-line treatment after failure of tyrosine kinase inhibitors. The case presented here implies that temsirolimus could be a viable option for patients with metastatic chromophobe renal cell carcinoma
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