636 research outputs found
Venturi air-jet vacuum ejectors for high-volume atmospheric sampling on aircraft platforms
Documentation of the installation and use of venturi air-jet vacuum ejectors for high-volume atmospheric sampling on aircraft platforms is presented. Information on the types of venturis that are useful for meeting the pumping requirements of atmospheric-sampling experiments is also presented. A description of the configuration and installation of the venturi system vacuum line is included with details on the modifications that were made to adapt a venturi to the NASA Electra aircraft at GSFC, Wallops Flight Facility. Flight test results are given for several venturis with emphasis on applications to the Differential Absorption Carbon Monoxide Measurement (DACOM) system at LaRC. This is a source document for atmospheric scientists interested in using the venturi systems installed on the NASA Electra or adapting the technology to other aircraft
Tomographic Separation of Composite Spectra. IX. The Massive Close Binary HD 115071
We present the first orbital elements for the massive close binary, HD
115071, a double-lined spectroscopic binary in a circular orbit with a period
of 2.73135 +/- 0.00003 days. The orbital semiamplitudes indicate a mass ratio
of M_2/M_1 = 0.58 +/- 0.02 and yet the stars have similar luminosities. We used
a Doppler tomography algorithm to reconstruct the individual component optical
spectra, and we applied well known criteria to arrive at classifications of
O9.5 V and B0.2 III for the primary and secondary, respectively. We present
models of the Hipparcos light curve of the ellipsoidal variations caused by the
tidal distortion of the secondary, and the best fit model for a Roche-filling
secondary occurs for an inclination of i = 48.7 +/- 2.1 degrees. The resulting
masses are 11.6 +/- 1.1 and 6.7 +/- 0.7 solar masses for the primary and
secondary, respectively, so that both stars are very overluminous for their
mass. The system is one of only a few known semi-detached, Algol-type binaries
that contain O-stars. We suggest that the binary has recently emerged from
extensive mass transfer (possibly through a delayed contact and common envelope
process).Comment: Submitted to Ap
Tomographic Separation of Composite Spectra. VIII. The Physical Properties of the Massive Compact Binary in the Triple Star System HD 36486 (delta Orionis A)
Double-lined spectroscopic orbital elements have recently been found for the
central binary in the massive triple, delta Orionis A based on radial
velocities from cross-correlation techniques applied to IUE high dispersion
spectra and He I 6678 spectra obtained at Kitt Peak. The primary and secondary
velocity amplitudes were found to be 94.9 +/- 0.6 km/s and 186 +/- 9 km/s
respectively. Tomographic reconstructions of the primary and secondary stars'
spectra confirm the O9.5 II classification of the primary and indicate a B0.5
III type for the secondary. The widths of the UV cross-correlation functions
are used to estimate the projected rotational velocities, Vsin i = 157 +/- 6
km/s and 138 +/- 16 km/s for the primary and secondary, respectively implying
that both stars rotate faster than their orbital motion. We used the
spectroscopic results to make a constrained fit of the Hipparcos light curve of
this eclipsing binary, and the model fits limit the inclination to the range
between 67 and 77 degrees. The i = 67 degrees solution, which corresponds to a
near Roche-filling configuration, results in a primary mass of 11.2 solar
masses and a secondary mass of 5.6 solar masses, both of which are
substantially below the expected masses for stars of their luminosity. This
binary may have experienced a mass ratio reversal caused by Case A Roche lobe
overflow, or the system may have suffered extensive mass loss through a binary
interaction, perhaps during a common envelope phase, in which most of the
primary's mass was lost from the system rather than transferred to the
secondary.Comment: 27 pages, 15 figures in press, the Astrophysical Journal, February 1,
200
A Spectroscopic Study of Mass Outflows in the Interacting Binary RY Scuti
The massive interacting binary RY Scuti is an important representative of an
active mass-transferring system that is changing before our eyes and which may
be an example of the formation of a Wolf-Rayet star through tidal stripping.
Utilizing new and previously published spectra, we present examples of how a
number of illustrative absorption and emission features vary during the binary
orbit. We identify spectral features associated with each component, calculate
a new, double-lined spectroscopic binary orbit, and find masses of 7.1 +/- 1.2
M_sun for the bright supergiant and 30.0 +/- 2.1 M_sun for the hidden massive
companion. Through tomographic reconstruction of the component spectra from the
composite spectra, we confirm the O9.7 Ibpe spectral class of the bright
supergiant and discover a B0.5 I spectrum associated with the hidden massive
companion; however, we suggest that the latter is actually the spectrum of the
photosphere of the accretion torus immediately surrounding the massive
companion. We describe the complex nature of the mass loss flows from the
system in the context of recent hydrodynamical models for beta Lyr, leading us
to conclude RY Scuti has matter leaving the system in two ways: 1) a bipolar
outflow from winds generated by the hidden massive companion, and 2) mass from
the bright O9.7 Ibpe supergiant flowing from the region near the L2 point to
fill out a large, dense circumbinary disk. This circumbinary disk (radius ~ 1
AU) may feed the surrounding double-toroidal nebula (radius ~ 2000 AU).Comment: 41 pages with 7 tables and 11 figures, accepted to Ap
A novel angiotensin I-converting enzyme mutation (S333W) impairs N-domain enzymatic cleavage of the anti-fibrotic peptide, AcSDKP
BACKGROUND: Angiotensin I-converting enzyme (ACE) has two functional N- and C-domain active centers that display differences in the metabolism of biologically-active peptides including the hemoregulatory tetrapeptide, Ac-SDKP, hydrolysed preferentially by the N domain active center. Elevated Ac-SDKP concentrations are associated with reduced tissue fibrosis. RESULTS: We identified a patient of African descent exhibiting unusual blood ACE kinetics with reduced relative hydrolysis of two synthetic ACE substrates (ZPHL/HHL ratio) suggestive of the ACE N domain center inactivation. Inhibition of blood ACE activity by anti-catalytic mAbs and ACE inhibitors and conformational fingerprint of blood ACE suggested overall conformational changes in the ACE molecule and sequencing identified Ser333Trp substitution in the N domain of ACE. In silico analysis demonstrated S333W localized in the S 1 pocket of the active site of the N domain with the bulky Trp adversely affecting binding of ACE substrates due to steric hindrance. Expression of mutant ACE (S333W) in CHO cells confirmed altered kinetic properties of mutant ACE and conformational changes in the N domain. Further, the S333W mutant displayed decreased ability (5-fold) to cleave the physiological substrate AcSDKP compared to wild-type ACE. Conclusions and Significance A novel Ser333Trp ACE mutation results in dramatic changes in ACE kinetic properties and lowered clearance of Ac-SDKP. Individuals with this mutation (likely with significantly increased levels of the hemoregulatory tetrapeptide in blood and tissues), may confer protection against fibrosis
World Workshop on Oral Medicine VII: Targeting the oral microbiome Part 2: Current knowledge on malignant and potentially malignant oral disorders.
Objective: The World Workshop on Oral Medicine VII chose the oral microbiome as a focus area. Part 1 presents the methodological state of the science for oral microbiome studies. Part 2 was guided by the question: What is currently known about the microbiome associated with oral squamous cell carcinoma and potentially malignant disorders of the oral mucosa?. Materials and Methods: A scoping review methodology was followed to identify and analyse relevant studies on the composition and potential functions of the oral microbiota using high-throughput sequencing techniques. The authors performed searches in PubMed and EMBASE. After removal of duplicates, a total of 239 potentially studies were identified. Results: Twenty-three studies on oral squamous cell carcinoma, two on oral leukoplakia and four on oral lichen planus were included with substantial differences in diagnostic criteria, sample type, region sequenced and sequencing method utilised. The majority of studies focused on bacterial identification and recorded statistically significant differences in the oral microbiota associated with health and disease. However, even when comparing studies of similar methodology, the microbial differences between health and disease varied considerably. No consensus on the composition of the microbiomes associated with these conditions on genus and species level could be obtained. Six studies on oral squamous cell carcinoma had included in silico predicted microbial functions (genes and/or pathways) and found some similarities between the studies. Conclusions: Attempts to reveal the microbiome associated with oral mucosal diseases are still in its infancy, and the studies demonstrate significant clinical and methodological heterogeneity across disease categories. The immense richness and diversity of the microbiota clearly illustrate that there is a need for additional methodologically comparable studies utilising deep sequencing approaches in significant cohorts of subjects together with functional analyses. Our hope is that following the recipe as outlined in our preceding companion paper, that is Part 1, will enhance achieving this in the future and elucidate the role of the oral microbiome in oral squamous cell carcinoma and potentially malignant disorders of the oral mucosa
Tomographic Separation of Composite Spectra. X. The Massive Close Binary HD 101131
We present the first orbital elements for the massive close binary, HD
101131, one of the brightest objects in the young, open cluster, IC 2944. This
system is a double-lined spectroscopic binary in an elliptical orbit with a
period of 9.64659 +/- 0.00012 days. It is a young system of unevolved stars
(approximately 2 million years old) that are well within their critical Roche
surfaces. We use a Doppler tomography algorithm to reconstruct the individual
component optical spectra, and we apply well known criteria to arrive at
classifications of O6.5 V((f)) and O8.5 V for the primary and secondary,
respectively. We compare the reconstructed spectra of the components to single
star, spectrum standards to determine a flux ratio of f_2/f_1 = 0.55 +/- 0.08
in the V-band. Both components are rotating faster than synchronously. We
estimate the temperatures and luminosities of the components from the observed
spectral classifications, composite V magnitude, and cluster distance modulus.
The lower limits on the masses derived from the orbital elements and the lack
of eclipses are 25 solar masses and 14 solar masses for the primary and
secondary, respectively. These limits are consistent with the larger masses
estimated from the positions of the stars in the Hertzsprung-Russell diagram
and evolutionary tracks for single stars.Comment: 17 pages, 3 figures, submitted to Ap
A randomized phase 2 study of temsirolimus and cetuximab versus temsirolimus alone in recurrent/metastatic, cetuximab‐resistant head and neck cancer: The MAESTRO study
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155947/1/cncr32929_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155947/2/cncr32929.pd
Comparative variation within the genome of Campylobacter jejuni NCTC 11168 in human and murine hosts
Sherpa Romeo green journal. Open access, distributed under the terms of the Creative Commons Attibution License.Campylobacteriosis incited by
C. jejuni
is a significant enteric disease of human beings. A person working with two reference
strains of
C. jejuni
National Collection of Type Cultures (NCTC) 11168 developed symptoms of severe enteritis including
bloody diarrhea. The worker was determined to be infected by
C. jejuni
. In excess of 50 isolates were recovered from the
worker’s stool. All of the recovered isolates and the two reference strains were indistinguishable from each other based on
comparative genomic fingerprint subtyping. Whole genome sequence analysis indicated that the worker was infected with
a
C. jejuni
NCTC 11168 obtained from the American Type Culture Collection; this strain (NCTC 11168-GSv) is the genome
sequence reference. After passage through the human host, major genetic changes including indel mutations within twelve
contingency loci conferring phase variations were detected in the genome of
C. jejuni
. Specific and robust single nucleotide
polymorphism (SNP) changes in the human host were also observed in two loci (Cj0144c, Cj1564). In mice inoculated with
an isolate of
C. jejuni
NCTC 11168-GSv from the infected person, the isolate underwent further genetic variation. At nine loci,
mutations specific to inoculated mice including five SNP changes were observed. The two predominant SNPs observed in
the human host reverted in mice. Genetic variations occurring in the genome of
C. jejuni
in mice corresponded to increased
densities of
C. jejuni
cells associated with cecal mucosa. In conclusion,
C. jejuni
NCTC 11168-GSv was found to be highly
virulent in a human being inciting severe enteritis. Host-specific mutations in the person with enteritis occurred/were
selected for in the genome of
C. jejuni
, and many were not maintained in mice. Information obtained in the current study
provides new information on host-specific genetic adaptation by
C. jejuni
.Ye
Binary and Multiple O-Type Stars in the Cas OB6 Association
We present the results of time-resolved spectroscopy of 13 O-type stars in
the Cas OB6 stellar association. We conducted a survey for radial velocity
variability in search of binary systems, which are expected to be plentiful in
young OB associations. Here we report the discovery of two new single-lined
binaries, and we present new orbital elements for three double-lined binaries
(including one in the multiple star system HD 17505). One of the double-lined
systems is the eclipsing binary system DN Cas, and we present a preliminary
light curve analysis that yields the system inclination, masses, and radii. We
compare the spectra of the single stars and the individual components of the
binary stars with model synthetic spectra to estimate the stellar effective
temperatures, gravities, and projected rotational velocities. We also make fits
of the spectral energy distributions to derive E(B-V), R=A_V/E(B-V), and
angular diameter. A distance of 1.9 kpc yields radii that are consistent with
evolutionary models. We find that 7 of 14 systems with spectroscopic data are
probable binaries, consistent with the high binary frequency found for other
massive stars in clusters and associations.Comment: 40 pages, ApJ, in pres
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