Simulation and optimization models for emergency medical systems planning.

The authors address strategic planning problems for emergency medical systems (EMS). In particular, the three following critical decisions are considered: i) how many ambulances to deploy in a given territory at any given point in time, to meet the forecasted demand, yielding an appropriate response time; ii) when ambulances should be used for serving nonurgent requests and when they should better be kept idle for possible incoming urgent requests; iii) how to define an optimal mix of contracts for renting ambulances from private associations to meet the forecasted demand at minimum cost. In particular, analytical models for decision support, based on queuing theory, discrete-event simulation, and integer linear programming were presented.

Molecular dynamics simulation of aqueous solutions of 26-unit segments of p(NIPAAm) and of p(NIPAAm) "doped" with amino acid based comonomers.

We have performed 75-ns molecular dynamics (MD) simulations of aqueous solutions of a 26-unit NIPAAm oligomer at two temperatures, 302 and 315 K, below and above the experimentally determined lower critical solution temperature (LCST) of p(NIPAAm). We have been able to show that at 315 K the oligomer assumes a compact form, while it keeps a more extended form at 302 K. A similar behavior has been demonstrated for a similar NIPAAm oligomer, where two units had been substituted by methacryloyl-l-valine (MAVA) comonomers, one of them being charged and one neutral.

Choledocholithiasis in Chinese immigrants with cholelithiasis.

During the period from January 1987 to December 1989, admissions for biliary tract disease at the New York Infirmary--Beekman Downtown Hospital were split almost evenly between Chinese immigrants from southeast Asia and all other ethnic groups (Caucasian, Hispanic, black, et cetera). However, the incidence of choledocholithiasis in patients undergoing cholecystectomy for cholelithiasis was much higher in the Chinese immigrant population, 37.2 versus 11.

Meptazinol and morphine in postoperative pain assessed with a new method for onset and duration.

Meptazinol, m-(3-ethyl-1-methyl-hexahydro-1-H-azepin-3-yl) phenol hydrochloride is a centrally active opioid analgesic with a specificity for the mu-1 receptor. It has been reported to lack many of the side effects commonly observed with morphine and morphinelike drugs in man. The objective of this study was to assess the analgesic efficacy and safety of meptazinol (50 mg and 100 mg) relative to morphine (5 mg and 10 mg) when administered intramuscularly for the treatment of postoperative pain.

Rectal perforation during barium enema. Report of a case.

Perforation of the colon or rectum during the course of barium-enema examination is estimated to occur in approximately 500 patients annually in the United States. It has been over 30 years since the last collective review on this subject reported a prohibitively high mortality and morbidity. Since that time, much has been learned about the treatment of patients with peritonitis and bowel perforation, many new and more effective antibiotics have become available, and the management of shock has become infinitely more sophisticated.