3,248 research outputs found
Palliative radiotherapy:New prognostic factors for patients with bone metastasis
Purpose: Many cancer patients develop bone metastases, however the prognosis of overall survival differs. To provide an optimal treatment for these patients, especially towards the end of life, a reliable prediction of survival is needed. The goal of this study was to find new clinical factors in relation to overall survival. Materials and methods: Prospectively 22 clinical factors were collected from 734 patients. The Kaplan–Meier and Cox regression models were used. Results: Most patients were diagnosed with lung cancer (29%), followed by prostate (19.8%) and breast cancer (14.7%). Median overall survival was 6.4 months. Fourteen clinical factors showed significance in the univariate analyses. In the multivariate analyses 6 factors were found to be significant for the overall survival: Karnofsky performance status, primary tumor, gender, total organs affected, morphine use and systemic treatment options after radiotherapy. Conclusion: Morphine use and systemic treatment options after radiotherapy, Karnofsky performance status, primary tumor, gender and total organs affected are strong prediction factors on overall survival after palliative radiotherapy in patients with bone metastasis. These factors are easily applicable in the clinic.</p
Recurrence of hepatitis C virus during leucocytopenia and spontaneous clearance after recovery from cytopenia: a case report
<p>Abstract</p> <p>Introduction</p> <p>There is little information about the risk of HCV recurrence in immunosuppressed patients. Although the presence of antibodies to HCV and the absence of HCV-RNA is usually considered to indicate viral elimination, the virus may not be completely eliminated but may be under control of an effective immune response.</p> <p>Case presentation</p> <p>A 69 year old man presented with jaundice, elevated ALT, AST, lipase and concomitant abdominal pain. He was found to be positive for HCV-RNA (genotype 3a) and was diagnosed with acute hepatitis C. Six weeks later no HCV-RNA was detected, and the patient was diagnosed with hyperthyreosis and started on propylthiouracil. After 4 weeks of propylthiouracil treatment, the patient developed leucocytopenia, followed by liver function deterioration and reappearance of HCV-RNA. Propylthiouracil was discontinued and his leukocyte counts increased. Twenty-eight weeks after onset of acute hepatitis C, no HCV-RNA was detected.</p> <p>Conclusion</p> <p>This case history shows the risk of recurrence of HCV during leucocytopenia. These findings indicate that patients who are anti-HCV positive but HCV-RNA negative may be at risk of cytopenia-induced HCV reactivation.</p
Expansion of W 3(OH)
A direct measurement of the expansion of W 3(OH) is made by comparing Very
Large Array images taken about 10 yr apart. The expansion is anisotropic with a
typical speed of 3 to 5 km/s, indicating a dynamical age of only 2300 yr. These
observations are inconsistent with either the freely expanding shell model or a
simple bow shock model. The most favored model is a slowly expanding shell-like
HII region, with either a fast rarefied flow or another less massive diffuse
ionized region moving towards the observer. There is also a rapidly evolving
source near the projected center of emission, perhaps related to the central
star.Comment: LaTeX file, 28 pages, includes 8 figures. To appear in ApJ in
December 10 (1998) issue. Also available at
http://www.submm.caltech.edu/~kawamura/w3oh_pp.p
Interpretation of radio continuum and molecular line observations of Sgr B2: free-free and synchrotron emission, and implications for cosmic rays
Recent ammonia (1,1) inversion line data on the Galactic star forming region
Sgr B2 show that the column density is consistent with a radial Gaussian
density profile with a standard deviation of 2.75 pc. Deriving a formula for
the virial mass of spherical Gaussian clouds, we obtain a virial mass of 1.9
million solar masses for Sgr B2. For this matter distribution, a reasonable
magnetic field and an impinging flux of cosmic rays of solar neighbourhood
intensity, we predict the expected synchrotron emission from the Sgr B2 giant
molecular cloud due to secondary electrons and positrons resulting from cosmic
ray interactions, including effects of losses due to pion production collisions
during diffusive propagation into the cloud complex.
We assemble radio continuum data at frequencies between 330 MHz and 230 GHz.
From the spectral energy distribution the emission appears to be thermal at
all frequencies. Before using these data to constrain the predicted synchrotron
flux, we first model the spectrum as free-free emission from the known ultra
compact HII regions plus emission from an envelope or wind with a radial
density gradient. This severely constrains the possible synchrotron emission by
secondary electrons to quite low flux levels. The absence of a significant
contribution by secondary electrons is almost certainly due to multi-GeV energy
cosmic rays being unable to penetrate far into giant molecular clouds. This
would also explain why 100 MeV--GeV gamma-rays (from neutral pion decay or
bremsstrahlung by secondary electrons) were not observed from Sgr B2 by EGRET,
while TeV energy gamma-rays were observed, being produced by higher energy
cosmic rays which more readily penetrate giant molecular clouds.Comment: 11 pages, 10 figures. New section on diffusion of primary and
secondary cosmic ray electrons into and within the Sgr B2 Giant Molecular
Cloud added. Main corrections to proofs made in this versio
An extragalactic supernebula confined by gravity
Little is known about the origins of the giant star clusters known as
globular clusters. How can hundreds of thousands of stars form simultaneously
in a volume only a few light years across the distance of the sun to its
nearest neighbor? Radiation pressure and winds from luminous young stars should
disperse the star-forming gas and disrupt the formation of the cluster.
Globular clusters in our Galaxy cannot provide answers; they are billions of
years old. Here we report the measurement of infrared hydrogen recombination
lines from a young, forming super star cluster in the dwarf galaxy, NGC 5253.
The lines arise in gas heated by a cluster of an estimated million stars, so
young that it is still enshrouded in gas and dust, hidden from optical view. We
verify that the cluster contains 4000-6000 massive, hot "O" stars. Our
discovery that the gases within the cluster are bound by gravity may explain
why these windy and luminous O stars have not yet blown away the gases to allow
the cluster to emerge from its birth cocoon. Young clusters in "starbursting"
galaxies in the local and distant universe may be similarly gravitationally
confined and cloaked from view.Comment: Letter to Natur
Recommended from our members
Search for new phenomena with the MT2 variable in the all-hadronic final state produced in proton-proton collisions at s=13 TeV.
A search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the MT2 variable. The results are based on a sample of proton-proton collisions collected in 2016 at a center-of-mass energy of 13 TeV with the CMS detector and corresponding to an integrated luminosity of 35.9 fb-1 . No excess event yield is observed above the predicted standard model background, and the results are interpreted as exclusion limits at 95% confidence level on the masses of predicted particles in a variety of simplified models of R-parity conserving supersymmetry. Depending on the details of the model, 95% confidence level lower limits on the gluino (light-flavor squark) masses are placed up to 2025 (1550) GeV . Mass limits as high as 1070 (1175) GeV are set on the masses of top (bottom) squarks. Information is provided to enable re-interpretation of these results, including model-independent limits on the number of non-standard model events for a set of simplified, inclusive search regions
N-band Observations of He 2-10: Unveiling the Dusty Engine of a Starburst Galaxy
To better understand the early stages of massive star cluster evolution we
have obtained J,H,K', and N (10.8 micron) images of the nuclear region of the
starburst galaxy He 2-10. The N-band images were obtained with the Gemini North
telescope and reveal four of the five enshrouded clusters, or "ultradense HII
regions" (UDHIIs), recently discovered in radio maps. None of these sources
appears in either the optical HST images or the near-infrared images. They
comprise about 60% of the total N-band flux from He 2-10 and, we suspect, a
similar fraction of the total far infrared flux measured by IRAS. The inferred
spectra of the UDHIIs are very similar to those of Galactic ultracompact HII
regions and we have modeled the UDHIIs under the assumption that they are
"scaled-up" versions of these objects. The bolometric luminosity of the
brightest UDHII is estimated to be ~2x10^9 L_sun, and the total mass of the
dust and gas is ~10^7 M_sun. The mass of the enshrouded stellar cluster must be
> 2.5x10^6 M_sun and the age must be < 4.8x10^6 yr. All of the stellar clusters
within the UDHIIs must have ages less than about 5x10^6 yr and masses greater
than about 5x10^5 M_sun. The logarithmic ratios of the radio to far infrared
flux densities for the individual UDHIIs, and He 2-10 as a whole, are
significantly larger than the average for normal galaxies, but comparable to
those for ultraluminous infrared galaxies. Large ratios for some starburst
galaxies may indicate that a significant fraction of the far infrared flux
arises from UDHIIs. If all of the far infrared flux from He 2-10 and other
starbursts is produced by heavily obscured regions, the observed correlation
between UV continuum slope and infrared-to-ultraviolet flux ratio in starbursts
cannot be due primarily to UV reprocessing by dust in a foreground screen.Comment: 41 pages, 9 figure
The Massive Star Content of NGC 3603
We investigate the massive star content of NGC 3603, the closest known giant
H II region. We have obtained spectra of 26 stars in the central cluster using
the Baade 6.5-m telescope (Magellan I). Of these 26 stars, 16 had no previous
spectroscopy. We also obtained photometry of all of the stars with previous or
new spectroscopy, primarily using archival HST ACS/HRC images. We use these
data to derive an improved distance to the cluster, and to construct an H-R
diagram for discussing the masses and ages of the massive star content of this
cluster.Comment: Accepted by the Astronomical Journal. This revision updates the
coordinates in Table 1 by (-0.18sec, +0.2") to place them on the UCAC2 syste
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