Study of star formation in RCW 106 using far infrared observations

High resolution far-infrared observations of a large area of the star forming complex RCW 106 obtained using the TIFR 1-metre balloon-borne telescope are presented. Intensity maps have been obtained simultaneously in two bands centred around 150 & 210 micron. Intensity maps have also been obtained at the 4 IRAS bands using HIRES processed IRAS data. From the 150 & 210 micron maps, reliable maps of dust temperature and optical depth have been generated. The star formation in this complex has occured in five linear subclumps. Using the map at 210 micron, which has a spatial resolution superior to that of the IRAS at 100 micron, 23 sources have been identified. The SED and luminosity of these sources have been determined using the associations wit hthe IRAS maps. Luminosity distribution of these sources has been obtained. Assuming these embedded sources to be ZAMS stars and using the mass-luminosity relation, the power law slope of the Initial Mass Function is found to be -1.73+-0.5. This index for this very young complex is about the same as that for more evolved complexes and clusters. Radiation transfer calculations in spherical geometry have been undertaken to fit the SEDs of 13 sources with fluxes in both the TIFR and IRAS bands. From this, the r^-2 density distribution in the envelopes is ruled out. Finally, a correlation is seen between the luminosity of embedded sources and the computed dust masses of the envelopes.Comment: Accepted for publication in MNRAS (21 pages, 8 figures & 3 tables

Production of carrier-free 28Mg by 50--200 MeV protons on natCl: excitation function and target optimization

Thick-target production rates and excitation function data are presented for 28Mg formed in the proton irradiation of natCl up to 200 MeV. The results are compared with previous literature experimental data, where available. Various compounds were investigated for their suitability as target materials. A practical target geometry utilizing encapsulated LiCl discs is suggested

Application of Au + p nuclear reactions for proton beam monitoring up to 70 MeV

Experimentally measured excitation functions are presented for the 197Au(p,n)197mHg, 197Au(p,pn)196Au, 197Au(p,3n)195mHg, 197Au(p,p3n)194Au and 197Au(p,5n)193mHg nuclear reactions up to 70 MeV. The new data are compared with published values, where available. Based on cubic spline fits through the data of the most reliable experimental data sets, recommended excitation function curves are suggested for the above nuclear processes

Application of Zn + p reactions for production of copper radioisotopes for medical studies

The production possibility of four medically important copper radioisotopes via Zn + p reactions was studied up to 80 MeV. Based on experimentally evaluated excitation function curves of the 64Zn(p,x)61Cu, natZn(p,x)62Zn → 62Cu, 66Zn(p,2pn)64Cu, 68Zn(p,x)64Cu and 68Zn(p,2p)67Cu reactions, production energy windows are recommended for the 61Cu, 62Cu, 64Cu and 67Cu isotopes. The available yields for these radioisotopes as well as the predicted yields of the major radiocontaminants are also presented

Carbon radioactivity of 223Ac and a search for nitrogen emission

A very intense 227Pa source was produced in order to study the possible 14C and 15N spontaneous emission from 223Ac. After the irradiation of a hemispherical, highly efficient array of nuclear track detectors, about 350 Carbon events were found leading to a branching ratio with respect to alpha decay B= 3.2 10^-11. Comparison with other 14C emitters allows the study of the influence of even-odd effects on cluster radioactivity

The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications

Background: The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications. Methods: ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery. Results: The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784. Conclusions: This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance. © 2018 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.Medical Research Council of South Africa gran