A computational algorithm for pole assignment of linear single-input systems

An efficient computational solution of the pole assignment problem of linear single-input systems is presented. It is based on orthogonal reduction of the closed-loop system matrix to upper (quasi-) triangular form whose 1 × 1 or 2 × 2 diagonal blocks correspond to the desired poles. The algorithm proposed is numerically stable and performs equally well with real and complex, distinct, and multiple desired poles. The number of the computational operations is less than6n^{3}, the necessary array storage being2n^{2} + 6nworking precision words, wherenis the order of the system.     

A 'potentially safer' route for puncture and injection of cornual ectopic pregnancies

Puncture and injection (usually by methotrexate) of ectopic pregnancies are relatively new modalities of treatment. Lately, these have been applied to cornual ectopic pregnancies. We describe here a proposed transvaginal ultrasound-guided puncture route, leading the needle into the cornual ectopic pregnancy, first traversing the myometrium and approaching the gestational sac from the medical aspect. After extracting the needle, there is potentially less chance for rupture and bleeding. In six of the seven injected cornual pregnancies, this technique was used without complication. The only one punctured from the lateral aspect bled and required laparoscopic intervention. This technique may enable the wider use of this treatment modality by lowering the complication rate caused by bleeding at the puncture site.     

Effect of polymerization temperature and time on the residual monomer content of denture base polymers

The aim of this study was to investigate the effect of polymerization time and polymerization temperature on the residual methyl methacrylate (MMA) content of two heat-cured and two autopolymerized denture base polymers. Gas chromatography was used to determine the residual MMA content of three test specimens of each type of polymer. Increasing the polymerization temperature for the autopolymerized denture base resins from 30 degrees C to 60 degrees C decreased the residual MMA content of the polymer from an average of 4.6 wt% to 3.3 wt%. With the heat-cured denture base resins, a curing cycle at a polymerization temperature of 70 degrees C followed by a period at 100 degrees C significantly reduced the residual monomer content of the polymer when compared with a resin cured at 70 degrees C only. Polymerizing the heat-cured denture base resin at 100 degrees C only for various lengths of time significantly affected the residual MMA content of the polymer. The lowest residual MMA content (0.07 wt%) was obtained by polymerizing the heat-cured denture base resin at 100 degrees C for 12 h. The results of this study suggest that the polymerization temperature and polymerization time considerably affect the residual MMA content of denture base polymers.     

Success rates with gamete intrafallopian transfer and in vitro fertilization in women of advanced maternal age

OBJECTIVE: To evaluate the effect of maternal age on outcomes for IVF and GIFT in women 40 to 45 years of age. DESIGN: Retrospective. SETTING: Boston IVF, a free-standing university-affiliated IVF and GIFT unit. PATIENTS: A total of 2,931 cycles of IVF and 1,826 cycles of GIFT were analyzed in women undergoing assisted reproductive technologies (IVF or GIFT) using autologous eggs. INTERVENTIONS: Medical records of patient outcomes were reviewed. RESULTS: For patients undergoing IVF, the cancellation rate for initiated cycles showed significant differences in women aged 25 to 39 (38.3%), women aged 40 to 43 (49.5%), and women aged 44 to 45 years (69.5%). A significantly lower delivery rate per stimulation and delivery rate per retrieval was found in women aged 40 to 43 years when compared with women aged 25 to 39 years. No deliveries occurred in 59 cycles in women aged 44 to 45 years, thereby representing a significant difference when compared with both women aged 25 to 39 years and women aged 40 to 43 years. For patients undergoing GIFT, the cancellation rate for initiated cycles was significantly higher in women aged 40 to 43 (25.0%) and 44 to 45 years (31.0%) when compared with women aged 25 to 39 years (15.1%). A significantly lower delivery rate per stimulation and delivery rate per retrieval was found in women aged 40 to 43 and 44 to 45 years when compared with women aged 25 to 39 years. CONCLUSIONS: Success rates for IVF and GIFT decline significantly in women > 40 years old. Women aged > or = 44 years are unlikely to benefit from the use of IVF and GIFT.