815 research outputs found
The SOFIA Massive (SOMA) Star Formation Survey. II. High Luminosity Protostars
We present multi-wavelength images observed with SOFIA-FORCAST from 10
to 40 m of seven high luminosity massive protostars, as part of the SOFIA
Massive (SOMA) Star Formation Survey. Source morphologies at these wavelengths
appear to be influenced by outflow cavities and extinction from dense gas
surrounding the protostars. Using these images, we build spectral energy
distributions (SEDs) of the protostars, also including archival data from
Spitzer, Herschel and other facilities. Radiative transfer (RT) models of Zhang
& Tan (2018), based on Turbulent Core Accretion theory, are then fit to the
SEDs to estimate key properties of the protostars. Considering the best five
models fit to each source, the protostars have masses accreting at rates of inside cores of initial masses embedded in clumps with mass surface densities and span a luminosity range of . Compared with the first eight protostars in Paper I, the sources
analyzed here are more luminous, and thus likely to be more massive protostars.
They are often in a clustered environment or have a companion protostar
relatively nearby. From the range of parameter space of the models, we do not
see any evidence that needs to be high to form these massive
stars. For most sources the RT models provide reasonable fits to the SEDs,
though the cold clump material often influences the long wavelength fitting.
However, for sources in very clustered environments, the model SEDs may not be
such a good description of the data, indicating potential limitations of the
models for these regions.Comment: 30 pages, 19 figures, Accepted for publication in Ap
The SOFIA Massive (SOMA) Star Formation Survey. I. Overview and First Results
We present an overview and first results of the Stratospheric Observatory For
Infrared Astronomy Massive (SOMA) Star Formation Survey, which is using the
FORCAST instrument to image massive protostars from
--. These wavelengths trace thermal emission from
warm dust, which in Core Accretion models mainly emerges from the inner regions
of protostellar outflow cavities. Dust in dense core envelopes also imprints
characteristic extinction patterns at these wavelengths, causing intensity
peaks to shift along the outflow axis and profiles to become more symmetric at
longer wavelengths. We present observational results for the first eight
protostars in the survey, i.e., multiwavelength images, including some
ancillary ground-based MIR observations and archival {\it{Spitzer}} and
{\it{Herschel}} data. These images generally show extended MIR/FIR emission
along directions consistent with those of known outflows and with shorter
wavelength peak flux positions displaced from the protostar along the
blueshifted, near-facing sides, thus confirming qualitative predictions of Core
Accretion models. We then compile spectral energy distributions and use these
to derive protostellar properties by fitting theoretical radiative transfer
models. Zhang and Tan models, based on the Turbulent Core Model of McKee and
Tan, imply the sources have protostellar masses --50
accreting at -- inside cores of
initial masses --500 embedded in clumps with mass surface
densities --3. Fitting Robitaille
et al. models typically leads to slightly higher protostellar masses, but with
disk accretion rates smaller. We discuss reasons for these
differences and overall implications of these first survey results for massive
star formation theories.Comment: Accepted to ApJ, 32 page
A Massive Protostar Forming by Ordered Collapse of a Dense, Massive Core
We present 30 and 40 micron imaging of the massive protostar G35.20-0.74 with
SOFIA-FORCAST. The high surface density of the natal core around the protostar
leads to high extinction, even at these relatively long wavelengths, causing
the observed flux to be dominated by that emerging from the near-facing outflow
cavity. However, emission from the far-facing cavity is still clearly detected.
We combine these results with fluxes from the near-infrared to mm to construct
a spectral energy distribution (SED). For isotropic emission the bolometric
luminosity would be 3.3x10^4 Lsun. We perform radiative transfer modeling of a
protostar forming by ordered, symmetric collapse from a massive core bounded by
a clump with high mass surface density, Sigma_cl. To fit the SED requires
protostellar masses ~20-34 Msun depending on the outflow cavity opening angle
(35 - 50 degrees), and Sigma_cl ~ 0.4-1 g cm-2. After accounting for the
foreground extinction and the flashlight effect, the true bolometric luminosity
is ~ (0.7-2.2)x10^5 Lsun. One of these models also has excellent agreement with
the observed intensity profiles along the outflow axis at 10, 18, 31 and 37
microns. Overall our results support a model of massive star formation
involving the relatively ordered, symmetric collapse of a massive, dense core
and the launching bipolar outflows that clear low density cavities. Thus a
unified model may apply for the formation of both low and high mass stars.Comment: 6 pages, 4 figures, 1 table, accepted to Ap
Nurses\u27 Alumnae Association Bulletin - Volume 6 Number 10
Financial Report
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Attention, Class of 1945!
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Report for Barton Memorial Hospital
Progress of the Orthopedic Department
Just Under the Date Line
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Controlled Respiration in Anesthesia
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Physical Advances at Jefferson During the Past Year
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Nurses\u27 Alumnae Association Bulletin - Volume 7 Number 11
Anna M. Shafer
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Locally advanced adenocarcinoma and adenosquamous carcinomas of the cervix compared to squamous cell carcinomas of the cervix in gynecologic oncology group trials of cisplatin-based chemoradiation
OBJECTIVE: Conflicting results have been reported for adeno- and adenosquamous carcinomas of the cervix with respect to their response to therapy and prognosis. The current study sought to evaluate impact of adeno- and adenosquamous histology in the randomized trials of primary cisplatin-based chemoradiation for locally advanced cervical cancer.
METHODS: Patients with adeno- and adenosquamous cervical carcinomas were retrospectively studied and compared to squamous cell carcinomas in GOG trials of chemoradiation.
RESULTS: Among 1671 enrolled in clinical trials of chemoradiation, 182 adeno- and adenosquamous carcinomas were identified (10.9%). A higher percentage of adeno- and adenosquamous carcinomas were stage IB2 (27.5% versus 20.0%) and fewer had stage IIIB (21.4% versus 28.6%). The mean tumor size was larger for squamous than adeno- and adenosquamous. Adeno- and adenosquamous carcinomas were more often poorly differentiated (46.2% versus 26.8%). When treated with radiation therapy alone, the 70 patients with adeno- and adenosquamous carcinoma of the cervix showed a statistically poorer overall survival (p=0.0499) compared to the 647 patients with squamous cell carcinoma of the cervix. However, when treated with radiation therapy with concurrent cisplatin-based chemotherapy, the 112 patients with adeno- and adenosquamous carcinomas had a similar overall survival (p=0.459) compared the 842 patients with squamous cell carcinoma. Adverse effects to treatment were similar across histologies.
CONCLUSION: Adeno- and adenosquamous carcinomas of the cervix are associated with worse overall survival when treated with radiation alone but with similar progression-free and overall survival compared to squamous cell carcinomas of the cervix when treated with cisplatin based chemoradiation
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Draft Genome Sequences of 1,183 Salmonella Strains from the 100K Pathogen Genome Project.
Salmonella is a common food-associated bacterium that has substantial impact on worldwide human health and the global economy. This is the public release of 1,183 Salmonella draft genome sequences as part of the 100K Pathogen Genome Project. These isolates represent global genomic diversity in the Salmonella genus
Contextualizing our Leadership Education Approach to Complex Problem Solving: Shifting Paradigms and Evolving Knowledge: Priority 5 of the National Leadership Education Research Agenda 2020–2025
Complex problems characterized by uncertainty, interconnectedness, poorly defined goals, and high risk are not new to the human experience. Yet humanity is increasingly faced with multifaceted and pervasive global challenges, and leadership education must adapt accordingly. These complex problems transcend borders and require a collective, adaptive, and iterative learning response. Complex problems such as failure to act on climate change, unemployment, food crises, governance failures, pandemics, cyberattacks, and involuntary migration are interrelated challenges that require paradigm shifts in responses and leadership (Global Risk Report, 2020)
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