Tertiary sub-system management: proceedings of one-day workshop held on June 18, 1995 in Lahore, Pakistan

Irrigation management / Watercourses / Institution building / Water conveyance / Water distribution / Irrigation practices / Economic aspects / Pakistan

Episodic accretion in binary protostars emerging from self-gravitating solar mass cores

Observations show a large spread in the luminosities of young protostars, which are frequently explained in the context of episodic accretion. We here test this scenario using numerical simulations following the collapse of a solar mass molecular cloud using the GRADSPH code, varying the strength of the initial perturbations and the temperature of the cores. A specific emphasis of this paper is to investigate the role of binaries and multiple systems in the context of episodic accretion, and to compare their evolution to the evolution in isolated fragments. Our models form a variety of low mass protostellar objects including single, binary and triple systems with binaries more active in exhibiting episodic accretion than isolated protostars. We also find a general decreasing trend for the average mass accretion rate over time, suggesting that the majority of the protostellar mass is accreted within the first 10^5 years. This result can potentially help to explain the surprisingly low average luminosities in the majority of the protostellar population.Comment: 16 pages, 13 figures, 4 tables. Accepted for publication with A&

Gallstone ileus: retrospective review of a single centre\u27s experience using two surgical procedures

Introduction:Gallstone ileus is responsible for 1-3 percent of cases of mechanical small bowel obstruction. Debate continues regarding choice of optimal surgical procedure. One-stage procedure includes enterolithotomy, cholecystectomy and repair of fistula at the same setting, whereas staged procedure includes enterolithotomy alone, with fistula repair at a later stage. This study aims to determine factors influencing choice of surgical procedure in Patients with gallstone ileus. Methods : Data was collected for Patients diagnosed with gallstone ileus between 1990 and 2005. Five Patients underwent enterolithotomy alone (Group 1), while the remaining five Patients underwent enterolithotomy with cholecystectomy and repair of fistula as a single stage procedure (Group 2). Results: In Group 1, Patients presented late with deranged physiological parameters and pre-existing comorbidities accounting for an American Society of Anesthesiologists (ASA) score of 3 or above. In Group 2, Patients presented early with preserved physiological status accounting for an ASA score of 2. The mean operative time was 126 +/- 23 minutes in Group 1 and 245 +/- 54.4 minutes in Group 2. There was no mortality, three Patients in Group 1 had superficial wound infection, and one Patient in Group 2 had injury to the common bile duct necessitating hepaticojejunostomy. The mean follow-up period was 3.5 +/- 1.5 years. None of the Patients in both groups had recurrent symptoms requiring further intervention. Conclusions: Choice of surgical procedure was largely determined by the clinical status of the Patient. Single-stage procedure was performed in haemodynamically-stable Patients, while enterolithotomy alone was considered sufficient for unstable Patients