1,216 research outputs found
Spitzer spectral line mapping of supernova remnants: I. Basic data and principal component analysis
We report the results of spectroscopic mapping observations carried out
toward small (1 x 1 arcmin) regions within the supernova remnants W44, W28,
IC443, and 3C391 using the Infrared Spectrograph of the Spitzer Space
Telescope. These observations, covering the 5.2 - 37 micron spectral region,
have led to the detection of a total of 15 fine structure transitions of Ne+,
Ne++, Si+, P+, S, S++, Cl+, Fe+, and Fe++; the S(0) - S(7) pure rotational
lines of molecular hydrogen; and the R(3) and R(4) transitions of hydrogen
deuteride. In addition to these 25 spectral lines, the 6.2, 7.7, 8.6, 11.3 and
12.6 micron PAH emission bands were also observed. Most of the detected line
transitions have proven strong enough to map in several sources, providing a
comprehensive picture of the relative distribution of the various line
emissions observable in the Spitzer/IRS bandpass. A principal component
analysis of the spectral line maps reveals that the observed emission lines
fall into five distinct groups, each of which may exhibit a distinct spatial
distribution: (1) lines of S and H2 (J > 2); (2) the H2 S(0) line; (3) lines of
ions with appearance potentials less than 13.6 eV; (4) lines of ions with
appearance potentials greater than 13.6 eV, not including S++; (5) lines of
S++. Lines of group (1) likely originate in molecular material subject to a
slow, nondissociative shock that is driven by the overpressure within the
supernova remnant, and lines in groups (3) - (5) are associated primarily with
dissociative shock fronts with a range of (larger) shock velocities. The H2
S(0) line shows a low-density diffuse emission component, and - in some sources
- a shock-excited component.Comment: 43 pages, including 21 figures. Accepted for publication in Ap
Detection of Extended Hot Water in the Outflow from NGC 2071
We report the results of spectroscopic mapping observations carried out
toward a ~1 min x 1 min region within the northern lobe of the outflow from NGC
2071 using the Infrared Spectrograph (IRS) of the Spitzer Space Telescope.
These observations covered the 5.2-37 um spectral region and have led to the
detection of a number of ionic, atomic, and molecular lines, including
fine-structure emission of Si+, Fe+, S++, S, the S(0)-S(7) pure rotational
lines of H2, the R(3) and R(4) transitions of HD, and at least 11 transitions
of H2O. In addition, the 6.2, 7.4, 7.6, 7.9, 8.6 and 11.3 um PAH emission bands
were also observed and several transitions of OH were tentatively detected.
Most of the detected line transitions were strong enough to map including, for
the first time, three transitions of hot H2O. We find that: (1) the water
emission is extended; (2) the extended emission is aligned with the outflow;
and, (3) the spatial distribution of the water emission generally follows that
observed for H2. Based on the measured line intensities, we derive an HD
abundance relative to H2 of 1.1-1.8 10^-5 and an H2O number density of 12-2
cm^3. The H2 density in the water-emitting region is not well constrained by
our observations, but is likely between 3 10^4 and 10^6 cm^3, yielding an H2O
abundance relative to H2 of between 2 10^-5 and 6 10^-4. Future observations
planned for the Herschel Space Observatory should greatly improve the density
estimate, and thus our knowledge of the H2O abundance, for the water-emitting
regions reported here. Finally, we note a possible departure from the H2O
ortho-to-para ratio of 3:1 expected for water formed in hot post-shocked gas,
suggesting that a significant fraction of the water vapor we detect may arise
from H2O sputtered from cold dust grains.Comment: 35 pages, 15 figures, 4 tables, accepted for publication in Ap
Confidence-Guided Unsupervised Domain Adaptation for Cerebellum Segmentation
The lack of a comprehensive high-resolution atlas of the cerebellum has
hampered studies of cerebellar involvement in normal brain function and
disease. A good representation of the tightly foliated aspect of the cerebellar
cortex is difficult to achieve because of the highly convoluted surface and the
time it would take for manual delineation. The quality of manual segmentation
is influenced by human expert judgment, and automatic labelling is constrained
by the limited robustness of existing segmentation algorithms. The
20umisotropic BigBrain dataset provides an unprecedented high resolution
framework for semantic segmentation compared to the 1000um(1mm) resolution
afforded by magnetic resonance imaging. To dispense with the manual annotation
requirement, we propose to train a model to adaptively transfer the annotation
from the cerebellum on the Allen Brain Human Brain Atlas to the BigBrain in an
unsupervised manner, taking into account the different staining and spacing
between sections. The distinct visual discrepancy between the Allen Brain and
BigBrain prevents existing approaches to provide meaningful segmentation masks,
and artifacts caused by sectioning and histological slice preparation in the
BigBrain data pose an extra challenge. To address these problems, we propose a
two-stage framework where we first transfer the Allen Brain cerebellum to a
space sharing visual similarity with the BigBrain. We then introduce a
self-training strategy with a confidence map to guide the model learning from
the noisy pseudo labels iteratively. Qualitative results validate the
effectiveness of our approach, and quantitative experiments reveal that our
method can achieve over 2.6% loss reduction compared with other approaches
Evaluation of binomial double sums involving absolute values
We show that double sums of the form can always be
expressed in terms of a linear combination of just four functions, namely
, , , and , with
coefficients that are rational in . We provide two different proofs: one is
algorithmic and uses the second author's computer algebra package Sigma; the
second is based on complex contour integrals. In many instances, these results
are extended to double sums of the above form where is
replaced by with independent parameter .Comment: AmS-LaTeX, 42 pages; substantial revision: several additional and
more general results, see Proposition 11 and Theorems 15-1
Destructive effects of murine arthritogenic antibodies to type II collagen on cartilage explants in vitro
Certain monoclonal antibodies (mAbs) to type II collagen (CII) induce arthritis in vivo after passive transfer and have adverse effects on chondrocyte cultures and inhibit self assembly of collagen fibrils in vitro. We have examined whether such mAbs have detrimental effects on pre-existing cartilage. Bovine cartilage explants were cultured over 21 days in the presence of two arthritogenic mAbs to CII (CIIC1 or M2139), a non-arthritogenic mAb to CII (CIIF4) or a control mAb (GAD6). Penetration of cartilage by mAb was determined by immunofluorescence on frozen sections and correlated with changes to the extracellular matrix and chondrocytes by morphometric analysis of sections stained with toluidine blue. The effects of mAbs on matrix components were examined by Fourier transform infrared microspectroscopy (FTIRM). A possible role of Fc-binding was investigated using F(ab)(2 )from CIIC1. All three mAbs to CII penetrated the cartilage explants and CIIC1 and M2139, but not CIIF4, had adverse effects that included proteoglycan loss correlating with mAb penetration, the later development in cultures of an abnormal superficial cellular layer, and an increased proportion of empty chondrons. FTIRM showed depletion and denaturation of CII at the explant surface in the presence of CIIC1 or M2139, which paralleled proteoglycan loss. The effects of F(ab)(2 )were greater than those of intact CIIC1. Our results indicate that mAbs to CII can adversely affect preformed cartilage, and that the specific epitope on CII recognised by the mAb determines both arthritogenicity in vivo and adverse effects in vitro. We conclude that antibodies to CII can have pathogenic effects that are independent of inflammatory mediators or Fc-binding
Organisation en réseau et durabilité systémique de deux filières alimentaires
La durabilité des filières alimentaires est questionnée par les pouvoirs publics et les consommateurs, qui tendent à défendre des formes alternatives de production, respectueuses de l'environnement, économiquement et socialement acceptables. Ces formes sont toutefois confrontées à des freins techniques, économiques et institutionnels d'où un questionnement sur leur capacité à se développer et à se maintenir, et donc sur leur durabilité. A partir d'une étude systémique de deux filières alternatives, le petit épeautre de Haute Provence et le riz biologique de Camargue, nous nous sommes attachés à comprendre comment l'organisation des acteurs peut influer sur les trois piliers du développement durable. Nous exposons une manière de considérer le développement durable qui met en avant les relations entre les acteurs, à l'aide de l'outil de l'analyse de réseau, et des entretiens menés avec un échantillon de différents acteurs des filières. Nous montrons que la volonté de pérennisation de la filière influe sur le choix du type d'organisation au sein de la filière, qui peut être orienté pour plus ou moins favoriser la prise en compte des piliers du développement durable. Nos observations montrent l'importance de considérer les réseaux dans une vision systémique de la durabilité. Il reste toutefois difficile d'établir des relations de causalité entre d'une part le type d'organisation et d'autre part la durabilité
Dosimetric comparison of extended dose range film with ionization measurements in water and lung equivalent heterogeneous media exposed to megavoltage photons
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135483/1/acm20025.pd
A Reexamination of Phosphorus and Chlorine Depletions in the Diffuse Interstellar Medium
We present a comprehensive examination of interstellar P and Cl abundances
based on an analysis of archival spectra acquired with the Space Telescope
Imaging Spectrograph of the Hubble Space Telescope and the Far Ultraviolet
Spectroscopic Explorer. Column densities of P II, Cl I, and Cl II are
determined for a combined sample of 107 sight lines probing diffuse atomic and
molecular gas in the local Galactic interstellar medium (ISM). We reevaluate
the nearly linear relationship between the column densities of Cl I and H,
which arises from the rapid conversion of Cl to Cl in regions where
H is abundant. Using the observed total gas-phase P and Cl abundances, we
derive depletion parameters for these elements, adopting the methodology of
Jenkins. We find that both P and Cl are essentially undepleted along sight
lines showing the lowest overall depletions. Increasingly severe depletions of
P are seen along molecule-rich sight lines. In contrast, gas-phase Cl
abundances show no systematic variation with molecular hydrogen fraction.
However, enhanced Cl (and P) depletion rates are found for a subset of sight
lines showing elevated levels of Cl ionization. An analysis of neutral chlorine
fractions yields estimates for the amount of atomic hydrogen associated with
the H-bearing gas in each direction. These results indicate that the
molecular fraction in the H-bearing gas is at least 10% for all sight lines
with and that the gas is essentially fully
molecular at .Comment: 44 pages, 21 figures, accepted for publication in Ap
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