108 research outputs found

    The Massive Star Content of NGC 3603

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    We investigate the massive star content of NGC 3603, the closest known giant H II region. We have obtained spectra of 26 stars in the central cluster using the Baade 6.5-m telescope (Magellan I). Of these 26 stars, 16 had no previous spectroscopy. We also obtained photometry of all of the stars with previous or new spectroscopy, primarily using archival HST ACS/HRC images. We use these data to derive an improved distance to the cluster, and to construct an H-R diagram for discussing the masses and ages of the massive star content of this cluster.Comment: Accepted by the Astronomical Journal. This revision updates the coordinates in Table 1 by (-0.18sec, +0.2") to place them on the UCAC2 syste

    Star Formation in the Starburst Cluster in NGC 3603

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    We have used new, deep, visible and near infrared observations of the compact starburst cluster in the giant HII region NGC 3603 and its surroundings with the WFC3 on HST and HAWK-I on the VLT to study in detail the physical properties of its intermediate mass (~ 1 - 3 M_sun) stellar population. We show that after correction for differential extinction and actively accreting stars, and the study of field star contamination, strong evidence remains for a continuous spread in the ages of pre-main sequence stars in the range ~ 2 to ~ 30 Myr within the temporal resolution available. Existing differences among presently available theoretical models account for the largest possible variation in shape of the measured age histograms within these limits. We also find that this isochronal age spread in the near infrared and visible Colour-Magnitude Diagrams cannot be reproduced by any other presently known source of astrophysical or instrumental scatter that could mimic the luminosity spread seen in our observations except, possibly, episodic accretion. The measured age spread and the stellar spatial distribution in the cluster are consistent with the hypothesis that star formation started at least 20-30 Myrs ago progressing slowly but continuously up to at least a few million years ago. All the stars in the considered mass range are distributed in a flattened oblate spheroidal pattern with the major axis oriented in an approximate South-East - North-West direction, and with the length of the equatorial axis decreasing with increasing age. This asymmetry is most likely due to the fact that star formation occurred along a filament of gas and dust in the natal molecular cloud oriented locally in this direction.Comment: 21 pages, 19 figures, accepted for publication in Astrophysics & Space Scienc

    Photon Dominated Regions in NGC 3603

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    Aims: We aim at deriving the excitation conditions of the interstellar gas as well as the local FUV intensities in the molecular cloud surrounding NGC 3603 to get a coherent picture of how the gas is energized by the central stars. Methods: The NANTEN2-4m submillimeter antenna is used to map the [CI] 1-0, 2-1 and CO 4-3, 7-6 lines in a 2' x 2' region around the young OB cluster NGC 3603 YC. These data are combined with C18O 2-1 data, HIRES-processed IRAS 60 and 100 micron maps of the FIR continuum, and Spitzer/IRAC maps. Results: The NANTEN2 observations show the presence of two molecular clumps located south-east and south-west of the cluster and confirm the overall structure already found by previous CS and C18O observations. We find a slight position offset of the peak intensity of CO and [CI], and the atomic carbon appears to be further extended compared to the molecular material. We used the HIRES far-infrared dust data to derive a map of the FUV field heating the dust. We constrain the FUV field to values of \chi = 3 - 6 \times 10^3 in units of the Draine field across the clouds. Approximately 0.2 to 0.3 % of the total FUV energy is re-emitted in the [CII] 158 {\mu}m cooling line observed by ISO. Applying LTE and escape probability calculations, we derive temperatures (TMM1 = 43 K, TMM2 = 47 K), column densities (N(MM1) = 0.9 \times 10^22 cm^-2, N(MM2) = 2.5 \times 10^22 cm^-2) and densities (n(MM1) = 3 \times 10^3 cm^-3, n(MM2) = 10^3 -10^4 cm^-3) for the two observed molecular clumps MM1 and MM2. Conclusions: The cluster is strongly interacting with the ambient molecular cloud, governing its structure and physical conditions. A stability analysis shows the existence of gravitationally collapsing gas clumps which should lead to star formation. Embedded IR sources have already been observed in the outskirts of the molecular cloud and seem to support our conclusions.Comment: 13 pages, 10 figures, accepted for publication by A&

    Impact of Obesity on Pediatric Acute Recurrent and Chronic Pancreatitis

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    OBJECTIVE: The aim of this study was to assess the impact of obesity on pediatric acute recurrent pancreatitis or chronic pancreatitis (CP). METHODS: We determined body mass index (BMI) status at enrollment in INSPPIRE (INternational Study group of Pediatric Pancreatitis: In search for a cuRE) cohort using CDC criteria for pediatric-specific BMI percentiles. We used the Cochran-Armitage test to assess trends and the Jonckheere-Terpstra test to determine associations. RESULTS: Of 446 subjects (acute recurrent pancreatitis, n = 241; CP, n = 205), 22 were underweight, 258 normal weight, 75 overweight, and 91 were obese. The BMI groups were similar in sex, race, and age at presentation. Hypertriglyceridemia was more common in overweight or obese. Obese children were less likely to have CP and more likely to have acute inflammation on imaging. Compared with children with normal weight, obese or overweight children were older at first acute pancreatitis episode and diagnosed with CP at an older age. Obese or overweight children were less likely to undergo medical or endoscopic treatment, develop exocrine pancreatic insufficiency, and require total pancreatectomy with islet autotransplantation. Diabetes was similar among all groups. CONCLUSIONS: Obesity or overweight seems to delay the initial acute pancreatitis episode and diagnosis of CP compared with normal weight or underweight. The impact of obesity on pediatric CP progression and severity deserves further study

    The Demise of Islet Allotransplantation in the US: A Call for an Urgent Regulatory Update The ISLETS FOR US Collaborative

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    Islet allotransplantation in the United States (US) is facing an imminent demise. Despite nearly three decades of progress in the field, an archaic regulatory framework has stymied US clinical practice. Current regulations do not reflect the state-of-the-art in clinical or technical practices. In the US, islets are considered biologic drugs and more than minimally manipulated human cell and tissue products (HCT/Ps). Across the world, human islets are appropriately defined as minimally manipulated tissue which has led to islet transplantation becoming a standard-of-care procedure for patients with type 1 diabetes mellitus and problematic hypoglycemia. As a result of the outdated US regulations, only eleven patients underwent allo-ITx in the US between 2011-2016 and all in the setting of a clinical trial. Herein, we describe the current regulations pertaining to islet transplantation in the United States. We explore the progress which has been made in the field and demonstrate why the regulatory framework must be updated to both, better reflect our current clinical practice and to deal with upcoming challenges. We propose specific updates to current regulations which are required for the renaissance of ethical, safe, effective, and affordable allo-ITx in the United States

    Chronic pancreatitis: Pediatric and adult cohorts show similarities in disease progress despite different risk factors

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    Objectives: To investigate the natural history of chronic pancreatitis (CP), patients in the North American Pancreatitis Study2 (NAPS2, adults) and INternational Study group of Pediatric Pancreatitis: In search for a cuRE (INSPPIRE, pediatric) were compared. Methods: Demographics, risk factors, disease duration, management and outcomes of 224 children and 1,063 adults were compared using appropriate statistical tests for categorical and continuous variables. Results: Alcohol was a risk in 53% of adults and 1% of children (p<0.0001); tobacco in 50% of adults and 7% of children (p<0.0001). Obstructive factors were more common in children (29% vs 19% in adults, p=0.001). Genetic risk factors were found more often in children. Exocrine pancreatic insufficiency was similar (children 26% vs adult 33%, p=0.107). Diabetes was more common in adults than children (36% vs 4% respectively, p<0.0001). Median emergency room visits, hospitalizations, and missed days of work/school were similar across the cohorts. As a secondary analysis, NAPS2 subjects with childhood onset (NAPS2-CO) were compared to INSPPIRE subjects. These two cohorts were more similar than the total INSPPIRE and NAPS2 cohorts, including for genetic risk factors. The only risk factor significantly more common in the NAPS2-CO cohort compared with the INSPPIRE cohort was alcohol (9% NAPS2-CO vs 1% INSPPIRE cohorts, p=0.011). Conclusions: Despite disparity in age of onset, children and adults with CP exhibit similarity in demographics, CP treatment, and pain. Differences between groups in radiographic findings and diabetes prevalence may be related to differences in risk factors associated with disease and length of time of CP

    Risk Factors for Rapid Progression From Acute Recurrent to Chronic Pancreatitis in Children: Report From INSPPIRE

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    Objective To determine the rate of progression from acute recurrent pancreatitis (ARP) to chronic pancreatitis (CP) in children and assess risk factors. Study Design Data were collected from the INternational Study group of Pediatric Pancreatitis: In search for a cuRE (INSPPIRE) cohort. Kaplan-Meier curves were constructed to calculate duration of progression from initial attack of acute pancreatitis (AP) to CP. Log-rank test was used to compare survival (non-progression) probability distribution between groups. Cox proportional hazard regression models were fitted to obtain hazard ratio (with 95% CI) of progression for each risk variable. Results Of 442 children, 251 had ARP, 191 CP. The median time of progression from initial attack of AP to CP was 3.79 years. The progression was faster in those age ≥6 years at the first episode of AP compared to those age <6 years (median time to CP: 2.91 vs 4.92 years; p=0.01). Children with pathogenic PRSS1 variants progressed more rapidly to CP compared to children without PRSS1 variants (median time to CP: 2.52 vs 4.48 years; p=0.003). Within six years after the initial AP attack, cumulative proportion with exocrine pancreatic insufficiency (EPI) was 18.0% (95% CI: 12.4%, 25.6%); diabetes mellitus was 7.7% (95% CI: 4.2%, 14.1%). Conclusions Children with ARP rapidly progress to CP, EPI and diabetes. The progression to CP is faster in children who were ≥6 years at the first episode of AP or with pathogenic PRSS1 variants. The factors that impact the aggressive disease course in childhood warrant further investigation

    Clinical and Practice Variations in Pediatric Acute Recurrent or Chronic Pancreatitis: Report From the INSPPIRE Study

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    Objective: The aim of the study was to determine whether clinical characteristics and management of pediatric acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) differ across INSPPIRE (INternational Study Group of Pediatric Pancreatitis: In Search for a cuRE) sites. Study design: Data were collected from INSPPIRE and analyzed per US regions and "non-US" sites. Between-group differences were compared by Pearson chi-square test. Differences in disease burden were compared by Kruskal-Wallis test. Results: Out of the 479 subjects, 121 (25%) were enrolled in West, 151 (32%) Midwest, 45 Northeast (9%), 78 (16%) South, and 84 (18%) at non-US sites. Hispanic ethnicity was more common in South (P < 0.0001); white race in Northeast (P = 0.009). CP was less common and time from diagnosis of first acute pancreatitis to CP was longer in children at non-US sites (P = 0.0002 and P = 0.011, respectively). Genetic mutations were most common among all groups; PRSS1 variants predominated in Midwest (P = 0.002). Gallstones were more frequent in South (P = 0.002). Endoscopic retrograde cholangiopancreatography (ERCP) and computed tomography (CT) imaging were more commonly utilized in United States compared with non-United States (P < 0.0001), but there were no differences in the use of MRI/MRCP. Disease burden was highest in the West and Midwest, possibly as total pancreatectomy and islet autotransplantation (TPIAT) referral sites were located in these regions. All therapies were less commonly administered in non-US sites (P < 0.0001). Conclusions: This is the first study to describe geographical variations in the INSPPIRE cohort, which possibly reflect variations in practice and referral patterns. The underlying reason behind the lower frequency of CP and fewer treatments in non-United States sites need to be further explored
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