633 research outputs found
High-Resolution Measurements of Intersystem Bands of Carbon Monoxide toward X Persei
In an echelle spectrum of X Per acquired with the Space Telescope Imaging
Spectrograph we have identified individual rotational lines of 11
triplet-singlet (intersystem) absorption bands of ^12CO. Four bands provide
first detections for interstellar clouds. From a comparison with the zeta Oph
sight line we find that X Per is obscured by a higher 12CO column density of
1.4 x 10^16 cm-2. Together with the high spectral resolution of 1.3 km s-1,
this allows (i) an improved measurement of previously published f-values for
seven bands, and (ii) an extraction of the first astrophysical oscillator
strengths for d-X (8-0), (9-0), and (10-0), as well as for e-X (12-0). The
^13CO d-X (12-0) band, previously suspected to exist toward zeta Oph, is now
readily resolved and modeled. Our derived intersystem f-values for ^12CO
include a few mild (leq 34%) disagreements with recent predictions from a
perturbation analysis calculated for the interstellar excitation temperature.
Overall, the comparison confirms the superiority of employing multiple singlet
levels in the calculations of mixing coefficients over previous single-level
predictions.Comment: 11 pages (incl. 1 figure). Accepted by ApJ Letter
Prevention of toxoplasmosis in pregnancy: knowledge of risk factors.
BACKGROUND: Infection with Toxoplasma gondii is common and usually asymptomatic, although it can have catastrophic consequences in a pregnant woman if passed to her developing fetus. Counseling of pregnant women about risk factor reduction may reduce the risk of congenital toxoplasmosis. This study was undertaken to assess and compare the knowledge of obstetricians and internists or family practitioners regarding well-established risk factors for toxoplasmosis infection. METHODS: The study surveyed 102 obstetricians, internists and family practitioners to assess their knowledge of risk factors for toxoplasmosis infection as well as their practices for primary prevention counseling of pregnant women. Responses were analyzed for differences. RESULTS: Obstetricians were more likely than internists or family practitioners to provide appropriate counseling on reducing the two most common risk factors for toxoplasmosis infection (undercooked meat consumption and gardening without gloves). However, over one quarter of all participants inappropriately advised pregnant women to avoid all cat contact. Obstetricians, internists and family practitioners were all likely to fail to identify undercooked meat consumption as the primary risk factor for toxoplasmosis transmission. CONCLUSIONS: Obstetricians appear to provide more appropriate counseling for primary prevention of toxoplasmosis than internists and family practitioners, but both groups of physicians inappropriately advised avoidance of all cat contact. Education of obstetricians, internists and family practitioners on risk factors for toxoplasmosis transmission is needed and may lower the rate of congenital toxoplasmosis as well as decrease the frequency of cat abandonment during pregnancy
FUSE Measurements of Interstellar Fluorine
The source of fluorine is not well understood, although core-collapse
supernovae, Wolf-Rayet stars, and asymptotic giant branch stars have been
suggested. A search for evidence of the nu process during Type II supernovae is
presented. Absorption from interstellar F I is seen in spectra of HD 208440 and
HD 209339A acquired with the Far Ultraviolet Spectroscopic Explorer. In order
to extract the column density for F I from the line at 954 A, absorption from
H2 has to be modeled and then removed. Our analysis indicates that for H2
column densities less than about 3 x 10^20 cm^-2, the amount of F I can be
determined from lambda 954. For these two sight lines, there is no clear
indication for enhanced F abundances resulting from the nu process in a region
shaped by past supernovae.Comment: 17 pages, 4 figures, accepted for publication in Ap
The Interstellar Rubidium Isotope Ratio toward Rho Ophiuchi A
The isotope ratio, 85Rb/87Rb, places constraints on models of the
nucleosynthesis of heavy elements, but there is no precise determination of the
ratio for material beyond the Solar System. We report the first measurement of
the interstellar Rb isotope ratio. Our measurement of the Rb I line at 7800 A
for the diffuse gas toward rho Oph A yields a value of 1.21 +/- 0.30 (1-sigma)
that differs significantly from the meteoritic value of 2.59. The Rb/K
elemental abundance ratio for the cloud also is lower than that seen in
meteorites. Comparison of the 85Rb/K and 87Rb/K ratios with meteoritic values
indicates that the interstellar 85Rb abundance in this direction is lower than
the Solar System abundance. We attribute the lower abundance to a reduced
contribution from the r-process. Interstellar abundances for Kr, Cd, and Sn are
consistent with much less r-process synthesis for the solar neighborhood
compared to the amount inferred for the Solar System.Comment: 12 pages with 2 figures and 1 table; will appear in ApJ Letter
Characterizing the immune microenvironment of malignant peripheral nerve sheath tumor by PD-L1 expression and presence of CD8+ tumor infiltrating lymphocytes.
BackgroundMalignant peripheral nerve sheath tumor (MPNST) is an aggressive sarcoma with few treatment options. Tumor immune state has not been characterized in MPNST, and is important in determining response to immune checkpoint blockade. Our aim was to evaluate the expression of programmed death-ligand 1 (PD-L1), programmed cell death protein 1 (PD-1), and presence of CD8+ tumor infiltrating lymphocytes (TILs) in MPNST, and correlate these findings with clinical behavior and outcome.ResultsPD-L1 staining of at least 1% was seen in 0/20 nerves, 2/68 benign lesions and 9/53 MPNST. Two of 68 benign lesions and 7/53 (13%) MPNST had at least 5% PD-L1 staining. CD8 staining of at least 5% was seen in 1/20 (5%) nerves, 45/68 (66%) benign lesions and 30/53 (57%) MPNST. PD-L1 was statistically more prevalent in MPNST than both nerves and benign lesions (p=0.049 and p=0.008, respectively). Expression of PD-1 was absent in all tissue specimens. There was no correlation of PD-L1 or CD8 expression with disease state (primary versus metastatic) or patient survival.MethodsA comprehensive PNST tissue microarray was created from 141 surgical specimens including primary, recurrent, and metastatic MPNST (n=53), neurofibromas (n=57), schwannoma (n=11), and normal nerve (n=20). Cores were stained in triplicate for PD-L1, PD-1, and CD8, and expression compared between tumor types. These data were then examined for survival correlates in 35 patients with primary MPNST.ConclusionsMPNST is characterized by low PD-L1 and absent PD-1 expression with significant CD8+ TIL presence. MPNST immune microenvironment does not correlate with patient outcome
A far UV study of interstellar gas towards HD34078: high excitation H2 and small scale structure - Based on observations performed by the FUSE mission and at the CFHT telescope
To investigate the presence of small scale structure in the spatial
distribution of H2 molecules we have undertaken repeated FUSE UV observations
of the runaway O9.5V star, HD34078. In this paper we present five spectra
obtained between January 2000 and October 2002. These observations reveal an
unexpectedly large amount of highly excited H2. Column densities for H2 levels
from (v = 0, J = 0) up to (v = 0, J = 11) and for several v = 1 and v = 2
levels are determined. These results are interpreted in the frame of a model
involving essentially two components: i) a foreground cloud (unaffected by
HD34078) responsible for the H2 (J = 0, 1), CI, CH, CH+ and CO absorptions; ii)
a dense layer of gas (n = 10E4 cm-3) close to the O star and strongly
illuminated by its UV flux which accounts for the presence of highly excited
H2. Our model successfully reproduces the H2 excitation, the CI fine-structure
level populations as well as the CH, CH+ and CO column densities. We also
examine the time variability of H2 absorption lines tracing each of these two
components. From the stability of the J = 0, 1 and 2 damped H2 profiles we
infer a 3 sigma upper limit on column density variations Delta(N(H2))/N(H2) of
5% over scales ranging from 5 to 50 AU. This result clearly rules out any
pronounced ubiquitous small scale "density" structure of the kind apparently
seen in HI. The lines from highly excited gas are also quite stable (equivalent
to Delta(N)/N <= 30%) indicating i) that the ambient gas through which HD34078
is moving is relatively uniform and ii) that the gas flow along the shocked
layer is not subject to marked instabilitie
CO emission and variable CH and CH+ absorption towards HD34078: evidence for a nascent bow shock ?
The runaway star HD34078, initially selected to investigate small scale
structure in a foreground diffuse cloud has been shown to be surrounded by
highly excited H2. We first search for an association between the foreground
cloud and HD34078. Second, we extend previous investigations of temporal
absorption line variations (CH, CH+, H2) in order to better characterize them.
We have mapped the CO(2-1) emission at 12 arcsec resolution around HD34078's
position, using the 30 m IRAM antenna. The follow-up of CH and CH+ absorption
lines has been extended over 5 more years. In parallel, CH absorption towards
the reddened star Zeta Per have been monitored to check the homogeneity of our
measurements. Three more FUSE spectra have been obtained to search for N(H2)
variations. CO observations show a pronounced maximum near HD34078's position,
clearly indicating that the star and diffuse cloud are associated. The optical
spectra confirm the reality of strong, rapid and correlated CH and CH+
fluctuations. On the other hand, N(H2, J=0) has varied by less than 5 % over 4
years. We also discard N(CH) variations towards Zeta Per at scales less than 20
AU. Observational constraints from this work and from 24 micron dust emission
appear to be consistent with H2 excitation but inconsistent with steady-state
bow shock models and rather suggest that the shell of compressed gas
surrounding HD34078, is seen at an early stage of the interaction. The CH and
CH+ time variations as well as their large abundances are likely due to
chemical structure in the shocked gas layer located at the stellar wind/ambient
cloud interface. Finally, the lack of variations for both N(H2, J=0) towards
HD34078 and N(CH) towards Zeta Per suggests that quiescent molecular gas is not
subject to pronounced small-scale structure.Comment: 19 pages, 15 figures, accepted for publication in A&
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