ABSTRACT
CONTEXT: High-mass stars and star clusters commonly form within hub-filament systems. Monoceros R2 (hereafter Mon R2), at a distance of 830 pc, harbors one of the closest such systems, making it an excellent target for case studies. AIMS: We investigate the morphology, stability and dynamical properties of the Mon R2 hub-filament system. METHODS: We employ observations of the 13CO and C18O 1â0 and 2â1 lines obtained with the IRAM-30m telescope. We also use H2 column density maps derived from Herschel dust emission observations. RESULTS: We identified the filamentary network in Mon R2 with the DisPerSE algorithm and characterized the individual filaments as either main (converging into the hub) or secondary (converging to a main filament) filaments. The main filaments have line masses of 30-100 M â pc-1 and show signs of fragmentation, while the secondary filaments have line masses of 12-60 M â pc-1 and show fragmentation only sporadically. In the context of Ostriker's hydrostatic filament model, the main filaments are thermally supercritical. If non-thermal motions are included, most of them are trans-critical. Most of the secondary filaments are roughly transcritical regardless of whether non-thermal motions are included or not. From the morphology and kinematics of the main filaments, we estimate a mass accretion rate of 10-4-10-3 M â yr-1 into the central hub. The secondary filaments accrete into the main filaments with a rate of 0.1-0.4×10-4 M â yr-1. The main filaments extend into the central hub. Their velocity gradients increase towards the hub, suggesting acceleration of the gas.We estimate that with the observed infall velocity, the mass-doubling time of the hub is ~ 2:5 Myr, ten times larger than the free-fall time, suggesting a dynamically old region. These timescales are comparable with the chemical age of the Hii region. Inside the hub, the main filaments show a ring- or a spiral-like morphology that exhibits rotation and infall motions. One possible explanation for the morphology is that gas is falling into the central cluster following a spiral-like pattern.
ABSTRACT
PURPOSE: Clinical tools for predicting postoperative pain should be developed to provide better care for patients. The aims of this study were to evaluate preoperative magnetic resonance imaging (MRI) findings to reveal reasons for overwhelming pain in patients with inguinal hernia and to detect changes in quality-of-life (QoL) and pain scores preoperatively and following laparoscopic totally extraperitoneal (TEP) repair of inguinal hernia. METHODS: Twenty-two patients aged 18-50 years presenting with extremely painful inguinal hernias (highest pain scores >50, scale 0-100) were examined with MRI prior to operative treatment with TEP repair. Postoperative follow-up lasted 6 months and consisted of questionnaires regarding functional status, pain, QoL and possible complications. Postoperative MRI scans were performed only in cases of preoperative findings on the MRI or prolonged inguinal pain persisting over 6 months. RESULTS: Prolonged postoperative pain could not be predicted from preoperative MRI scans, because no signs of the pain's origin such as pubic periostal irritation, bone marrow edema, pelvic bone or hip joint abnormalities, or lower abdominal muscle hemorrhage were detected in MRI. TEP repair of inguinal hernia significantly improved the patients' quality of life and relieved pain symptoms. High preoperative pain scores were major predictors of prolonged postoperative pain. CONCLUSIONS: Carefully evaluated preoperative pelvic MRI was usually normal in patients with high pain scores prior to operation. Preoperative pain scores may serve as indicators of development of prolonged inguinal pain.
