NC Med J July/August 2007, Volume 68, Number 4 ike other organizations, emergency medical services (EMS) systems have revenues and expenses. The unpredictability of calls and the oftentimes inefficient nature of EMS operations make EMS management and financing difficult. Annually, EMS costs patients, insurers, and the federal government billions of dollars. In fiscal year 2002, Medicare spent $...

We consider the single-commodity single-origin fixed-charge network flow problem (SSFNP) defined on a directed network G = (V,A), where V is the node set and A is the arc set, with each arc a represented by the ordered pair of head and tail nodes (h(a), t(a)). The node set includes a single origin (with no incoming arc), multiple destinations (with no outgoing arc) and transshipment nodes (with...

Scheduling is an important subject of production and operations management area. In flow-shop scheduling, the objective is to obtain a sequence of jobs which when processed in a fixed order of machines, will optimize some well defined criteria. The concept of transportation time is very important in scheduling. Transportation can be done by robots. In situations that robots are used to transpor...

A three-level relief chain including a number of suppliers in fixed locations, candidate distribution centers and affected areas at certain points are considered. A mixed integer nonlinear programming model is proposed for open transportation location routing problem by considering split delivery of demand. To solve a realistic problem, foregoing parameters are considered as fuzzy in our propos...

A difference in salt concentration in two solutions separated by a membrane leads to an electrical potential difference across the membrane, also without applied current. A literature study is presented on proposed theories for the origin of this membrane potential (ϕm). The most well-known theoretical description is Teorell-Meyer-Sievers (TMS) theory, which we analyze and extend. Experimental ...

Large-volume, high-temperature Bose-Einstein condensation is illustrated for a relativistic O(2)-invariant scalar field with fixed charge using the canonical ensemble. The standard, grand canonical results are reproduced for the infinite-volume limit. Finite-volume corrections are calculated and the results are found to differ from the grand canonical approximation in a consistent qualitative w...

This paper proposes a numerical model for describing charge accumulation in electron-beam irradiated low density polyethylene. The model is bipolar, and based on a previous model dedicated to space charge accumulation in solid dielectrics under electrical stress. It encompasses the generation of positive and negative charges due to the electron beam and their transport in the insulation. A sens...