1,643 research outputs found
Temperatures of dust and gas in S~140
In dense parts of interstellar clouds (> 10^5 cm^-3), dust & gas are expected
to be in thermal equilibrium, being coupled via collisions. However, previous
studies have shown that the temperatures of the dust & gas may remain decoupled
even at higher densities. We study in detail the temperatures of dust & gas in
the photon-dominated region S 140, especially around the deeply embedded
infrared sources IRS 1-3 and at the ionization front. We derive the dust
temperature and column density by combining Herschel PACS continuum
observations with SOFIA observations at 37 m and SCUBA at 450 m. We
model these observations using greybody fits and the DUSTY radiative transfer
code. For the gas part we use RADEX to model the CO 1-0, CO 2-1, 13CO 1-0 and
C18O 1-0 emission lines mapped with the IRAM-30m over a 4' field. Around IRS
1-3, we use HIFI observations of single-points and cuts in CO 9-8, 13CO 10-9
and C18O 9-8 to constrain the amount of warm gas, using the best fitting dust
model derived with DUSTY as input to the non-local radiative transfer model
RATRAN. We find that the gas temperature around the infrared sources varies
between 35 and 55K and that the gas is systematically warmer than the dust by
~5-15K despite the high gas density. In addition we observe an increase of the
gas temperature from 30-35K in the surrounding up to 40-45K towards the
ionization front, most likely due to the UV radiation from the external star.
Furthermore, detailed models of the temperature structure close to IRS 1 show
that the gas is warmer and/or denser than what we model. Finally, modelling of
the dust emission from the sub-mm peak SMM 1 constrains its luminosity to a few
~10^2 Lo. We conclude that the gas heating in the S 140 region is very
efficient even at high densities, most likely due to the deep UV penetration
from the embedded sources in a clumpy medium and/or oblique shocks.Comment: 15 pages, 23 figures, 4 tables, accepted for publication in A&
Water emission from the high-mass star-forming region IRAS 17233-3606. High water abundances at high velocities
We investigate the physical and chemical processes at work during the
formation of a massive protostar based on the observation of water in an
outflow from a very young object previously detected in H2 and SiO in the IRAS
17233-3606 region. We estimated the abundance of water to understand its
chemistry, and to constrain the mass of the emitting outflow. We present new
observations of shocked water obtained with the HIFI receiver onboard Herschel.
We detected water at high velocities in a range similar to SiO. We
self-consistently fitted these observations along with previous SiO data
through a state-of-the-art, one-dimensional, stationary C-shock model. We found
that a single model can explain the SiO and H2O emission in the red and blue
wings of the spectra. Remarkably, one common area, similar to that found for H2
emission, fits both the SiO and H2O emission regions. This shock model
subsequently allowed us to assess the shocked water column density,
N(H2O)=1.2x10^{18} cm^{-2}, mass, M(H2O)=12.5 M_earth, and its maximum
fractional abundance with respect to the total density, x(H2O)=1.4x10^{-4}. The
corresponding water abundance in fractional column density units ranges between
2.5x10^{-5} and 1.2x10^{-5}, in agreement with recent results obtained in
outflows from low- and high-mass young stellar objects.Comment: accepted for publication as a Letter in Astronomy and Astrophysic
Abundant H2D+ in the pre-stellar core L1544
We have detected the 372 GHz line of ortho-H2D+ towards the pre-stellar core
L1544. The strongest emission (T_mb ~ 1 K) occurs at the peak of the millimeter
continuum emission, while measurements at offset positions indicate that H2D+
is confined within ~ 20 arcsec, where CO is highly depleted. The derived H2D+
abundance of ~ 10^{-9} is comparable with previous estimates of the electron
abundance in the core, which suggests that H2D+ is the main molecular ion in
the central 20 arcsec (2800 AU) of L1544. This confirms the expectations that
H2D+ is dramatically enhanced in gas depleted of molecules other than H2. The
measured abundance even exceeds the present model predictions by about a factor
ten. One possibility is that all CNO-bearing neutral species, including atomic
oxygen, are almost completely (> 98%) frozen within a radius of ~2800 AU.Comment: A&A Letters, in pres
Motor learning principles during rehabilitation after anterior cruciate ligament injury:Time to create an enriched environment to improve clinical outcome
Athletes who wish to resume high-level activities after an injury to the anterior cruciate ligament (ACL) are often advised to undergo surgical reconstruction. Nevertheless, ACL reconstruction (ACLR) does not equate to normal function of the knee or a reduced risk of subsequent injuries. A rising concern is the high rate of secondary ACL injuries, particularly in young athletes, with up to 40% of those returning to sport in the first year after surgery experiencing a second ACL rupture. Aside from the increased risk of secondary injury, patients after ACLR have an increased risk of developing early-onset osteoarthritis. Unfortunately, current ACLR rehabilitation programs may not be optimally effective in terms of addressing deficits related to the initial injury and the subsequent surgical intervention. Motor learning to (re)acquire motor skills and neuroplastic capacities are not sufficiently incorporated during traditional rehabilitation, attesting to the high reinjury rates. The purpose of this article is to present novel clinically integrated motor learning principles to support neuroplasticity that can improve patient functional performance and reduce the risk of secondary ACL injury. The novel motor learning principles presented in this manuscript may optimize future rehabilitation programs to reduce the risk of secondary ACL injury and early development of osteoarthritis by targeting changes in neural networks.</p
Synovial tissue response to rituximab: mechanism of action and identification of biomarkers of response
OBJECTIVE: To investigate the synovial tissue in patients with rheumatoid arthritis (RA) treated with rituximab and to identify possible predictors of clinical response. METHODS: A total of 24 patients with RA underwent synovial biopsy before, 4 and 16 weeks after initiation of rituximab treatment (without peri-infusional corticosteroids to prevent bias). Immunohistochemical analysis was performed and stained sections were analysed by digital image analysis. Linear regression analysis was used to identify predictors of clinical response. RESULTS: The 28-joint Disease Activity Score (DAS28) was unaltered at 4 weeks, but significantly reduced at 16 and 24 weeks. Serum levels of IgM-rheumatoid factor (RF) decreased significantly at 24 weeks and anti-citrullinated peptide antibody (ACPA) levels at 36 weeks. Peripheral blood B cells were depleted at 4 weeks and started to return at 24 weeks. Synovial B cells were significantly decreased at 4 weeks, but were not completely depleted in all patients; there was a further reduction at 16 weeks in some patients. We found a significant decrease in macrophages at 4 weeks, which was more pronounced at 16 weeks. At that timepoint, T cells were also significantly decreased. The reduction of plasma cells predicted clinical improvement at 24 weeks. CONCLUSIONS: The results support the view that B cells orchestrate local cellular infiltration. The kinetics of the serological as well as the tissue response in clinical responders are consistent with the notion that rituximab exerts its effects in part by an indirect effect on plasma cells associated with autoantibody production, which could help explain the delayed response after rituximab treatmen
TWEAK and its receptor Fn14 in the synovium of patients with rheumatoid arthritis compared to psoriatic arthritis and its response to tumour necrosis factor blockade
Objective: To investigate the expression of tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) and its receptor fibroblast growth factor inducible 14 (Fn14) in the inflamed synovium of patients with arthritis, as TWEAK blockade has been observed to have a beneficial effect in an animal model of rheumatoid arthritis (RA). Methods: Synovial tissue (ST) biopsies were obtained from 6 early, methotrexate-naive patients with RA as well as 13 patients with RA and 16 patients with psoriatic arthritis (PsA) who were matched for treatment and disease duration. Serial ST samples were obtained from a separate cohort of 13 patients with RA before and after infliximab treatment. TWEAK and Fn14 expression was evaluated by immunohistochemistry and digital image analysis. Results: TWEAK and Fn14 were clearly expressed in ST of patients with RA and PsA. TWEAK expression was significantly higher in RA (sub) lining samples compared to PsA (p = 0.005 and p = 0.014, respectively), but Fn14 expression was comparable. Double immunofluorescence showed TWEAK and Fn14 expression on fibroblast-like synoviocytes and macrophages, but not T cells. Of interest, persistent TWEAK and Fn14 expression was found after anti-TNF therapy. Conclusions: TWEAK and Fn14 are abundantly expressed in the inflamed synovium of patients with RA and PsA. This raises the possibility that blocking TWEAK/Fn14 signalling could be of therapeutic benefit in inflammatory arthriti
Water in massive star-forming regions: HIFI observations of W3 IRS5
We present Herschel observations of the water molecule in the massive
star-forming region W3 IRS5. The o-H17O 110-101, p-H18O 111-000, p-H2O 22
202-111, p-H2O 111-000, o-H2O 221-212, and o-H2O 212-101 lines, covering a
frequency range from 552 up to 1669 GHz, have been detected at high spectral
resolution with HIFI. The water lines in W3 IRS5 show well-defined
high-velocity wings that indicate a clear contribution by outflows. Moreover,
the systematically blue-shifted absorption in the H2O lines suggests expansion,
presumably driven by the outflow. No infall signatures are detected. The p-H2O
111-000 and o-H2O 212-101 lines show absorption from the cold material (T ~ 10
K) in which the high-mass protostellar envelope is embedded. One-dimensional
radiative transfer models are used to estimate water abundances and to further
study the kinematics of the region. We show that the emission in the rare
isotopologues comes directly from the inner parts of the envelope (T > 100 K)
where water ices in the dust mantles evaporate and the gas-phase abundance
increases. The resulting jump in the water abundance (with a constant inner
abundance of 10^{-4}) is needed to reproduce the o-H17O 110-101 and p-H18O
111-000 spectra in our models. We estimate water abundances of 10^{-8} to
10^{-9} in the outer parts of the envelope (T < 100 K). The possibility of two
protostellar objects contributing to the emission is discussed.Comment: Accepted for publication in the A&A HIFI special issu
Inhibition of the production of mediators of inflammation by corticosteroids is a glucocorticoid receptor-mediated process
In order to find an explanation for corticosteroid resistance we assessed whether inhibition by dexamethasone (DEX) of the stimulated production of TNF-â, IL-6, PGE2 and LTB4 by peripheral blood mononuclear cells (MNC) depends on binding to the glucocorticoid receptor (GR), and whether it is determined by the number or the affinity of the GR of these cells. GR number and affinity of MNC were determined by means of a whole cell DEX binding assay. MNC were incubated with DEX and LPS or A23187 in the absence or presence of RU486, a potent steroid antagonist. DEX caused a concentration dependent inhibition of TNF-â, IL-6 and PGE2 production but had no effect on LTB4 production. RU486 significantly blocked the effect of DEX, but no correlations were found between the inhibition of mediator release and the Kd or receptor number
NH_3(1_0-0_0) in the pre-stellar core L1544
Pre-stellar cores represent the initial conditions in the process of star and
planet formation, therefore it is important to study their physical and
chemical structure. Because of their volatility, nitrogen-bearing molecules are
key to study the dense and cold gas present in pre-stellar cores. The NH_3
rotational transition detected with Herschel-HIFI provides a unique combination
of sensitivity and spectral resolution to further investigate physical and
chemical processes in pre-stellar cores. Here we present the velocity-resolved
Herschel-HIFI observations of the ortho-NH_3(1_0-0_0) line at 572 GHz and study
the abundance profile of ammonia across the pre-stellar core L1544 to test
current theories of its physical and chemical structure.
Recently calculated collisional coefficients have been included in our
non-LTE radiative transfer code to reproduce Herschel observations. A gas-grain
chemical model, including spin-state chemistry and applied to the (static)
physical structure of L1544 is also used to infer the abundance profile of
ortho-NH_3 . The hyperfine structure of ortho-NH_3(1_0-0_0) is resolved for the
first time in space. All the hyperfine components are strongly self-absorbed.
The profile can be reproduced if the core is contracting in quasi-equilibrium,
consistent with previous work, and if the NH_3 abundance is slightly rising
toward the core centre, as deduced from previous interferometric observations
of para-NH_3(1,1). The chemical model overestimates the NH_3 abundance at radii
between ~ 4000 and 15000 AU by about two orders of magnitude and underestimates
the abundance toward the core centre by more than one order of magnitude. Our
observations show that chemical models applied to static clouds have problems
in reproducing NH_3 observations.Comment: accepted for publication in A&A Letter
The Different Structures of the Two Classes of Starless Cores
We describe a model for the thermal and dynamical equilibrium of starless
cores that includes the radiative transfer of the gas and dust and simple CO
chemistry. The model shows that the structure and behavior of the cores is
significantly different depending on whether the central density is either
above or below about 10^5 cm-3. This density is significant as the critical
density for gas cooling by gas-dust collisions and also as the critical density
for dynamical stability, given the typical properties of the starless cores.
The starless cores thus divide into two classes that we refer to as thermally
super-critical and thermally sub-critical.This two-class distinction allows an
improved interpretation of the different observational data of starless cores
within a single model.Comment: ApJ in pres
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