Aims: Revealing the 3D dynamics of H II region bubbles and their associated molecular clouds and H I envelopes is important for developing an understanding of the longstanding problem as to how ...stellar feedback affects the density structure and kinematics of the different phases of the interstellar medium. Methods: We employed observations of the H II region RCW 120 in the C II 158 μm line, observed within the Stratospheric Observatory for Infrared Astronomy (SOFIA) legacy program FEEDBACK, and in the 12CO and 13CO (3 →2) lines, obtained with the Atacama Pathfinder Experiment (APEX) to derive the physical properties of the gas in the photodissociation region (PDR) and in the molecular cloud. We used high angular resolution H I data from the Southern Galactic Plane Survey to quantify the physical properties of the cold atomic gas through H I self-absorption. The high spectral resolution of the heterodyne observations turns out to be essential in order to analyze the physical conditions, geometry, and overall structure of the sources. Two types of radiative transfer models were used to fit the observed C II and CO spectra. A line profile analysis with the 1D non-LTE radiative transfer code SimLine proves that the CO emission cannot stem from a spherically symmetric molecular cloud configuration. With a two-layer multicomponent model, we then quantified the amount of warm background and cold foreground gas. To fully exploit the spectral-spatial information in the CO spectra, a Gaussian mixture model was introduced that allows for grouping spectra into clusters with similar properties. Results: The CO emission arises mostly from a limb-brightened, warm molecular ring, or more specifically a torus when extrapolated in 3D. There is a deficit of CO emission along the line-of-sight toward the center of the H II region which indicates that the H II region is associated with a flattened molecular cloud. Self-absorption in the CO line may hide signatures of infalling and expanding molecular gas. The C II emission arises from an expanding C II bubble and from the PDRs in the ring/torus. A significant part of C II emission is absorbed in a cool (~60-100 K), low-density (<500 cm−3) atomic foreground layer with a thickness of a few parsec. Conclusions: We propose that the RCW 120 H II region formed in a flattened, filamentary, or sheet-like, molecular cloud and is now bursting out of its parental cloud. The compressed surrounding molecular layer formed a torus around the spherically expanding H II bubble. This scenario can possibly be generalized for other H II bubbles and would explain the observed "flat" structure of molecular clouds associated with H II bubbles. We suggest that the C II absorption observed in many star-forming regions is at least partly caused by low-density, cool, H I -envelopes surrounding the molecular clouds. The 12CO and 13CO (3 →2) data shown in Fig. 4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/659/A36 The C II data are provided at the NASA/IPAC Infrared science archive at https://irsa.ipac.caltech.edu/Missions/sofia.html
The objective of this study was to evaluate a simplified version of the Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) reduced to five joints of the hand (RAMRIS5).
94 patients with ...rheumatoid arthritis (62 female; age 59±12 years, range 25-83 years; disease duration 60±90 months (median: 22 months, first quartile: 7 months, third quartile: 66 months) from the REMISSION PLUS study cohort who had complete files on C-reactive protein (CRP) levels and Disease Activity Score of 28 joints (DAS28) and complete MRI of the clinical dominant hand at baseline and after one year under anti-rheumatic therapy (follow-up time 12.5±1.1 months) in a dedicated extremity MRI scanner at 0.2T were included in this retrospective study.
There was a strong correlation between RAMRIS5 and the RAMRIS sum-score for all patients (r=0.87, p<0.001) at baseline and follow-up (r=0.87, p<0.001). Among the subscores there was a significant correlation between RAMRIS5 and RAMRIS-MCP (baseline: r=0.66, p<0.001; follow-up: r=0.74, p<0.001) as well as between RAMRIS5 and RAMRIS-wrist (baseline: r=0.72, p<0.001, follow-up: r=0.69, p<0.001) at baseline and follow-up.
RAMRIS5, a modified shorter RAMRIS score based on five joints of the hand is a viable tool for semi-quantitative assessment of joint damage in RA. This abbreviated score might reduce the time needed for image analysis in MRI-controlled studies in RA and might facilitate the use of MRI in studies on therapy response assessment in RA.
Zusammenfassung
Die Magnetresonanztomographie (MRT) bildet bei rheumatologischen Erkrankungen entzündliche Frühveränderungen ab, die anderen bildgebenden Techniken entgehen können. Neue ...MRT-Protokolle und Hardware, hierunter die Ganzkörper-MRT und die Niederfeld-MRT, führen zu einer Erweiterung des diagnostischen Armentariums und einem potenziellen diagnostischen Zugewinn bei der Anwendung. Die wachsende Zahl funktioneller MRT-Sequenzen, die Informationen über die molekulare Zusammensetzung der untersuchten Gewebe, allen voran des Gelenkknorpels, eröffnen ferner neue Möglichkeiten der molekularen, respektive präklinischen Bildgebung. Hybride MRT-Verfahren wie die MR-SPECT (Single-Photonen-Emissionstomographie) oder MR-PET (Positronenemissionstomographie) sprechen über eine Kombination aus Abbildung von Morphologie und Akquisition von Metabolismus eine neue Ebene der Bildgebungsmodalitäten an, die bislang bei rheumatologischen Fragestellungen noch nicht ausgiebig erforscht sind. Dieser Beitrag bietet einen Up-to-date-Überblick über neue MRT-Verfahren und Techniken sowie über die innovative Hybridbildgebung und fasst erste Ergebnisse ihrer Anwendungen bei rheumatischen Erkrankungen zusammen.
Aims. Within the framework of the Herschel M 33 extended survey HerM33es and in combination with multi-wavelength data we study the spectral energy distribution (SED) of a set of H ii regions in the ...Local Group galaxy M 33 as a function of the morphology. We analyse the emission distribution in regions with different morphologies and present models to infer the Hα emission measure observed for H ii regions with well defined morphology. Methods. We present a catalogue of 119 H ii regions morphologically classified: 9 filled, 47 mixed, 36 shell, and 27 clear shell H ii regions. For each object we extracted the photometry at twelve available wavelength bands, covering a wide wavelength range from FUV-1516 Å (GALEX) to IR-250 μm (Herschel), and we obtained the SED for each object. We also obtained emission line profiles in vertical and horizontal directions across the regions to study the location of the stellar, ionised gas, and dust components. We constructed a simple geometrical model for the clear shell regions, whose properties allowed us to infer the electron density of these regions. Results. We find trends for the SEDs related to the morphology of the regions, showing that the star and gas-dust configuration affects the ratios of the emission in different bands. The mixed and filled regions show higher emission at 24 μm, corresponding to warm dust, than the shells and clear shells. This could be due to the proximity of the dust to the stellar clusters in the case of filled and mixed regions. The far-IR peak for shells and clear shells seems to be located towards longer wavelengths, indicating that the dust is colder for this type of object. The logarithmic 100 μm/70 μm ratio for filled and mixed regions remains constant over one order of magnitude in Hα and FUV surface brightness, while the shells and clear shells exhibit a wider range of values of almost two orders of magnitude. We derive dust masses and dust temperatures for each H ii region by fitting the individual SEDs with dust models proposed in the literature. The derived dust mass range is between 102−104 M⊙ and the cold dust temperature spans Tcold ~ 12−27 K. The spherical geometrical model proposed for the Hα clear shells is confirmed by the emission profile obtained from the observations and is used to infer the electron density within the envelope: the typical electron density is 0.7 ± 0.3 cm-3, while filled regions can reach values that are two to five times higher.
Dense Gas in M33 (HerM33es) Buchbender, C.; Kramer, C.; Gonzalez-Garcia, M. ...
Astronomy and astrophysics (Berlin),
2013, Letnik:
549
Journal Article
Recenzirano
Odprti dostop
We aim to better understand the emission of molecular tracers of the diffuse and dense gas in giant molecular clouds and the influence that metallicity, optical extinction, density, far-UV field, and ...star formation rate have on these tracers. Using the IRAM 30m telescope, we detected HCN, HCO+, 12CO, and 13CO in six GMCs along the major axis of M33 at a resolution of ~ 114pc and out to a radial distance of 3.4kpc. Optical, far-infrared, and submillimeter data from Herschel and other observatories complement these observations. To interpret the observed molecular line emission, we created two grids of models of photon-dominated regions, one for solar and one for M33-type subsolar metallicity. The observed HCO+/HCN line ratios range between 1.1 and 2.5. Similarly high ratios have been observed in the Large Magellanic Cloud. The HCN/CO ratio varies between 0.4% and 2.9% in the disk of M33. The 12CO/13CO line ratio varies between 9 and 15 similar to variations found in the diffuse gas and the centers of GMCs of the Milky Way. Stacking of all spectra allowed HNC and C2H to be detected. The resulting HCO+/HNC and HCN/HNC ratios of ~ 8 and 6, respectively, lie at the high end of ratios observed in a large set of (ultra-)luminous infrared galaxies. HCN abundances are lower in the subsolar metallicity PDR models, while HCO+ abundances are enhanced. For HCN this effect is more pronounced at low optical extinctions. The observed HCO+/HCN and HCN/CO line ratios are naturally explained by subsolar PDR models of low optical extinctions between 4 and 10 mag and of moderate densities of n = 3x10^3 - 3x10^4 cm^-3, while the FUV field strength only has a small effect on the modeled line ratios. The line ratios are almost equally well reproduced by the solar-metallicity models, indicating that variations in metallicity only play a minor role in influencing these line ratios.
Within the framework of the HERM33ES key project, we are studying the star forming interstellar medium in the nearby, metal-poor spiral galaxy M33, exploiting the high resolution and sensitivity of ...Herschel. We use PACS and SPIRE maps at 100, 160, 250, 350, and 500 micron wavelength, to study the variation of the spectral energy distributions (SEDs) with galacto-centric distance. Detailed SED modeling is performed using azimuthally averaged fluxes in elliptical rings of 2 kpc width, out to 8 kpc galacto-centric distance. Simple isothermal and two-component grey body models, with fixed dust emissivity index, are fitted to the SEDs between 24 and 500 micron using also MIPS/Spitzer data, to derive first estimates of the dust physical conditions. The far-infrared and submillimeter maps reveal the branched, knotted spiral structure of M33. An underlying diffuse disk is seen in all SPIRE maps (250-500 micron). Two component fits to the SEDs agree better than isothermal models with the observed, total and radially averaged flux densities. The two component model, with beta fixed at 1.5, best fits the global and the radial SEDs. The cold dust component clearly dominates; the relative mass of the warm component is less than 0.3% for all the fits. The temperature of the warm component is not well constrained and is found to be about 60K plus/minus 10K. The temperature of the cold component drops significantly from about 24K in the inner 2 kpc radius to 13K beyond 6 kpc radial distance, for the best fitting model. The gas-to-dust ratio for beta=1.5, averaged over the galaxy, is higher than the solar value by a factor of 1.5 and is roughly in agreement with the subsolar metallicity of M33.
Zielsetzung:
Vergleich der 18F-FDG PET/MRT unter Verwendung kontrastmittelgestützter, T1w, fettgesättigter (fs) VIBE Bildsequenzen und der 18F-FDG PET/CT bezüglich Detektion und Charakterisierung von ...Lungenrundherden bei onkologischen Patienten.
Material und Methodik:
Bei 121 onkologischen Patienten wurde nach einer PET/CT eine anschließende PET/MRT unter Ausnutzung der residualen 18F-FDG Aktivität durchgeführt. Die Detektionsrate der T1w fs VIBE sowie der PET Datensätze für Lungenrundherde wurde jeweils in Relation zur CT berechnet (Referenzstandard). Unterschiede zwischen T1w fs VIBE und CT bezüglich Läsionskontrast (Vier-Punkte-Skala) und Läsionsgröße, sowie zwischen den Fusionsbildern bezüglich Bildqualität (Vier-Punkte-Skala), SUVmean, SUVmax und Dignität (benigne/maligne) wurden anhand von Wilcoxon-Tests auf Signifikanz geprüft. Zudem wurde das Ausmaß der Korrelation für SUV-Werte und Läsionsgröße mit Pearsons Koeffizienten (r) und für Läsionskontrast mit Spearmans Rangkorrelationskoeffizienten (ρ) quantifiziert.
Ergebnisse:
Die Detektionsraten der T1w fs VIBE, der PET des PET/CT und der PET des PET/MRT für insgesamt 241 Lungenrundherde lagen bei 66.8%, 42.7%, und 42.3%. Läsionsgröße (r = 0.98) und SUVs (r = 0.91) korrelierten stark, in puncto Läsionskontrast gab es eine moderate Korrelation (ρ= 0.48). Die Bildqualität der PET/MRT war niedriger als die der PET/CT (p < 0.001). Korrespondierende Lungenrundherde wurden in den T1w fs VIBE Bildern kleiner abgebildet als im CT (p < 0.001). SUVmax und SUVmean von PET-positiven Läsionen wurden im PET/MRT höher gemessen als im PET/CT (p < 0.001). Bezüglich Läsionskontrast und Dignität wurden keine signifikanten Unterschiede festgestellt.
Schlussfolgerungen:
Die Detektierbarkeit von Lungenrundherden in der PET/MRT mit T1w VIBE Bildsequenzen ist der PET/CT unterlegen. Daher birgt das Staging onkologischer Patienten mittels PET/MRT ein Risiko, Lungenmetastasen zu verpassen.
Zielsetzung:
Evaluation des diagnostischen Nutzens der 18F-FDG PET/MRT, der 18F-FDG PET/CT, der MRT und der CT im Ganzkörper-Staging von Patienten mit Brustkrebsrezidiven.
Material und Methodik:
Bei ...21 Patienten mit Verdacht auf Brustkrebsrezidiv wurde anschließend an eine PET/CT die PET/MRT unter Ausnutzung des residualen 18F-FDG Aktivität durchgeführt. PET/MRT, PET/CT, die CT Komponente der PET/CT (CTPET/CT) und die MRT Bilder der PET/MRT (MRTPET/MRT) wurden separat bezüglich Anzahl, Lokalisation und Dignität (benigne/maligne) von Läsionen ausgewertet. Der Referenzstandard für Dignität basierte auf histologischen Untersuchungen und radiologischer Verlaufsbildgebung. Unterschiede zwischen PET/MRT und PET/CT im SUVmax von korrespondierenden PET-positiven Läsionen wurden durch einen Wilcoxon-Test quantifiziert. Zudem wurde der SUVmax mittels des Pearsons Koeffizienten intermodal korreliert. Die Interrater-Übereinstimmung bezüglich Dignität wurde durch Cohens kappa ermittelt.
Ergebnisse:
Bei 17 der 21 Patienten lag ein Brustkrebsrezidiv vor. PET/MRT, PET/CT und MRTPET/MRT erlaubten die korrekte Identifikation aller Patienten, wohingegen mittels CTPET/CT nur bei 15 der 17 Patienten ein Brustkrebsrezidiv erkannt wurde. Insgesamt wurden 134 Läsionen gefunden (116 maligne, 18 benigne). Bezüglich der Dignität der Läsionen ließ sich mittels 18F-FDG PET/MRI mit 98.5% der höchste Anteil an korrekt gewerteten Läsionen diagnostizieren. Der Anteil war im PET/CT (94.8%), MRTPET/MRT (88.1%) und CTPET/CT (57.5%) jeweils niedriger. Der SUVmax korrelierte stark (r = 0.72), im PET/MRT lag er jedoch signifikant über dem der PET/CT (SUVmax: 5.6 ± 2.8 vs. 4.9 ± 1.8; p = 0.001). Die Interrater-Übereinstimmung mit PET/MRT und PET/CT erwies sich als deutlich (jeweils k = 0.65). Mit MRTPET/MRT ergab sich eine moderate (k = 0.56) und mit CTPET/CT eine niedrige Übereinstimmung (k = 0.31).
Schlussfolgerungen:
Die 18F-FDG PET/MRT zeigte das höchste diagnostische Potenzial und bietet sich daher als wertvolle Alternative im Ganzkörper-Staging bei Brustkrebsrezidiven an.
![Self-absorption in [C II], ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-6361/small "Self-absorption in [C II], 12CO, and H I in RCW120. Building up a geometrical and physical model of the region")
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