Mortality and morbidity after coronary bypass surgery in high-risk patients

A total of 113 women and 912 men were submitted to coronary artery bypass surgery at Surgical Department A, Rikshospitalet between August 1982 and December 1986 and followed till January 1993. We found no difference in early mortality, recurrent angina pectoris or non-fatal myocardial infarction in diabetic patients compared to nondiabetic patients. However, total mortality was 1.87 times higher in the diabetic group. For patients with ejection fraction < or = 40%, early mortality was 10.2 times higher than for the reference group. For total mortality we found a practically linear relationship between increased mortality and falling ejection fraction values. We found no relationship between ejection fraction and recurrent angina and non-fatal myocardial infarction, neither did we find any difference in mortality and morbidity between women and men. Although a somewhat higher mortality and morbidity rate must be expected for high-risk patients, they seem to profit to the same extent from the favourable effects of coronary bypass surgery as other patients.     

Synthesis and effect of vanadium pentoxide nanoparticles on dielectric relaxation and ac conductivity of polyvinyl alcohol

The dielectric parameters of polyvinyl alcohol containing 0–0.8 wt. % vanadium pentoxide are studied in the temperature range 20–150 °C at different frequencies: the dielectric constant, dielectric losses, and tangent of the angle of dielectric losses. Cole–Cole plots are used to determine the static dielectric constant and the dielectric constant at infinitely high frequency. The relaxation time is determined at different frequencies as a function of the tangent of the angle of dielectric losses versus the temperature. It is found that the relaxation properties follow the Arrhenius equation, the activation energy decreases with the vanadium pentoxide content in polyvinyl alcohol. An investigation of the dielectric relaxation as a function of temperature at constant frequency revealed two types of relaxation processes: dipole-segmented motion (α-relaxation) and side-chain dipole group motion (β-relaxation). The ac conductivity in the system polyvinyl alcohol––vanadium pentoxide is explained on the basis of the correlated barrier hopping model.     

A self learned invasive weed-mixed biogeography based optimization algorithm for RFID network planning

The optimal placement of the RFID readers inaugurates an ongoing research field, namely the RFID network planning (RNP). The main issue in the RNP is to know how many readers have to be used and what is their best distribution that guarantees fulfillment of multiple objectives. The common RNP objectives are the optimal coverage, readers’ interference avoidance, redundant reader elimination, load balance among deployed readers and minimum power losses, which are considered as conflicting objectives that leads the RNP to be an NP-hard problem need to be solved. The contributions in this paper are: firstly, utilizing both the Biogeography based optimization (BBO) and the Hybrid Invasive Weed-Biogeography based optimization (HIW-BBO) as new algorithms have not used before for solving the RNP. Secondly, we proposed a Self Learning (SL) strategy with a mixed BBO Migration (MBBOM) operation to modify the HIW-BBO algorithm in an algorithm called Self Learned Invasive Weed-Mixed Biogeography based optimization (SLIWMBBO). Thirdly, the performance of the proposed SLIWMBBO algorithm is compared to both the HIW-BBO and the Self Adaptive Cuckoo Search (SACS) optimization algorithms according to a set of 13 benchmark functions. The results of this comparison encourage the application of the SLIWMBBO as an optimization algorithm for solving the complex problems. Lastly, the BBO, HIW-BBO and SLIWMBBO optimization algorithms are used for solving three complex RNP instances and compared to the SACS algorithm. Simulation results of the SLIWMBBO are outstanding and demonstrate its superiority over the compared algorithms.