Adjustable temporal suture in trabeculectomy with scleral flap

BACKGROUND AND OBJECTIVE: The long-term success of trabeculectomy depends primarily on the degree of scarring that occurs to the artificial filtration route that is created by the procedure. The most serious postoperative complication of trabeculectomy is a persistent shallow anterior chamber or a flat chamber. The objective of this study was to evaluate the effect of a suturing technique on the long-term success of trabeculectomy. PATIENTS AND METHODS: In this study, the authors analyzed a trabeculectomy technique that is based on the application of a suture of variable tightness on the scleral flap. The technique was performed on 11 patients subjected to trabeculectomy. RESULTS: The postoperative complication of shallow anterior chamber was successfully treated with further tightening of the suture for one patient. For each patient, the authors loosened the suture on the fourth postoperative day and removed it completely on the seventh or eighth postoperative day. The patients were observed postoperatively for a minimum of 1 year. During this period the intraocular pressure for each patient was within the normal limits. CONCLUSION: The authors contend that this trabeculectomy technique, in which a suture on the scleral flap can be adjusted for tightness and is later removed, contributes significantly to the treatment of a postoperative shallow anterior chamber or a flat chamber and to the long-term function of an effective filtration fistula.     

Reducing residential fuel consumption through cost-effective interseasonal energy transfer

Energy savings obtainable through effective interseasonal energy transfer are explored by means of a detailed dynamic computer simulation. The mechanism of interseasonal energy transfer is the solar assisted Annual Cycle Energy System (ACES). The operational concept of the ACES is discussed and the modeling methodology used in evaluating the system is presented. Annual energy consumption and associated costs are investigated for the Full, Minimum and Cost Optimized ACES in a variety of U.S. climates. The energy and economic effectiveness of the ACES is evaluated by comparing the ACES to four conventional heating and cooling systems. Results show that the ACES can be three to four times more energy efficient than the conventional systems investigated in this study. Under prototype equipment cost constraints, the residential ACES are not, in general, cost competitive with the conventional systems. However, with realistic projections on the cost of mature components, the residential ACES are far superior to the conventional systems.     

Theoretical analysis of the dynamic interactions of vapor compression heat pumps

A detailed mathematical model of vapor compression heat pumps is described. Model derivations of the various heat pump components are given. The component models include the condenser, evaporator, accumulator, expansion device, and compressor. Details of the modeling techniques are presented, as is the solution methodology. Preliminary simulation results are also illustrated. The model developed predicts the spatial values of temperature and enthalpy as functions of time for the two heat exchangers. The temperatures and enthalpies in the accumulator, compressor and expansion device are modeled in lumped-parameter fashion. Pressure responses are determined by using continuity satisfying models for both the condenser and evaporator. The discussion of the solution methodology describes the combined implicit/explicit integration formulation that is used to solve the governing equations. The summary provides a list of future work anticipated in the area of dynamic heat pump modeling.