Methodology for load compensation in four-wire electrical power systems based on instantaneous sampling

This work describes a methodology for power factor control and correction of the unbalanced currents in four-wire electric circuits. The methodology is based on the insertion of two compensation networks, one wye-grounded neutral and other in delta, in parallel to the load. The mathematical development has been proposed in previous work [3]. In this paper, however, the determination of the compensation susceptances is based on the instantaneous values of load currents. The results are obtained using the MatLab-Simulink enviroment

ALTERNATIVE SAMPLING STRATEGY FOR A RANDOM OPTIMIZATION ALGORITHM

Alternative sampling procedures are compared to the pure random search method. It is shown that the efficiency of the algorithm can be improved with respect to the expected number of steps to reach an epsilon-neighborhood of the optimal point.

VSSI (X)over-bar charts with sampling at fixed times

A standard (X) over bar chart for controlling the process mean takes samples of size no at specified, equally-spaced, fixed-time points. This article proposes a modification of the standard (X) over bar chart that allows one to take additional samples, bigger than no, between these fixed times. The additional samples are taken from the process when there is evidence that the process mean moved from target. Following the notation proposed by Reynolds (1996a) and Costs (1997) we shortly call the proposed (X) over bar chart as VSSIFT (X) over bar chart: where VSSIFT means variable sample size and sampling intervals with fixed times. The (X) over bar chart with the VSSIFT feature is easier to be administered than a standard VSSI (X) over bar chart that is not constrained to sample at the specified fixed times. The performances of the charts in detecting process mean shifts are comparable.

The frequency of 844ins68 mutation in the cystathionine beta-synthase gene is not increased in patients with venous thrombosis

Background and Objectives. A frequent mutation in the cystathionine beta-synthase (CBS) gene (844ins68, a 68-bp insertion in the coding region of exon 8) was recently discovered. In the present study we Investigated this mutation as a candidate risk factor for venous thrombosis.Design and Methods. The prevalence of the 844ins68 CBS mutation was determined in 101 patients with objectively diagnosed deep venous thrombosis and in 101 healthy controls matched for age, sex and race. PCR amplification of a DNA fragment containing exon 8 of the CBS gene was employed to determine the genotypes, Additionally, Bsrl restriction enzyme digestion of the PCR products was performed in all samples from carriers of the insertion, to test for concurrent presence of a second mutation (T833C) in the CBS gene.Results. The insertion was found in 21 out of 101 patients (20.8%; allele frequency 0.109) and in 20 out of 101 controls (19.8%; allele frequency 0.114), yielding a relative risk for venous thrombosis related to the 844ins68 CBS mutation close to 1.0. In addition, the T833C GBS mutation was detected in all alleles carrying the 844ins68 CBS insertion, confirming the co-inheritance of the two mutations.Interpretation and Conclusions. Our findings do not support the hypothesis that the 844ins68 mutation in the CBS gene is a genetic risk factor for venous thrombosis. (C)1998, Ferrata Storti Foundation.

Identification of polymorphisms in the 5 '-untranslated region of the TAFI gene: relationship with plasma TAFI levels and risk of venous thrombosis

Background and Objectives. Thrombin activatable fibrinolysis inhibitor (TAFI) plays an important role in hemostasis, functioning as a potent fibrinolysis inhibitor. TAFI gene variations may contribute to plasma TAFI levels and thrombotic risk.Design and Methods. We sequenced a 2083-bp region of the 5 ' -regulatory region of the TAFI gene in 127 healthy subjects searching for variations, and correlated identified polymorphisms with plasma TAFI levels. TAFI polymorphisms were examined as risk factors for venous thrombosis by determining their prevalence in 388 patients with deep venous thrombosis (DVT) and in 388 controls.Results. Seven novel polymorphisms were identified: -152 A/G, -438 A/G, -530 C/T, -1053 T/C, -1102 T/G, -1690 G/A, and -1925 T/C. -152 A/G, -530 C/T and -1925 T/C were found to be in strong linkage disequilibrium, as were the -438 A/G, -1053 T/C, -1102 T/G and -1690 G/A, Plasma TAFI levels were higher in -43866/-1053CC/-1102GG/-1690AA homozygotes than In -438AG/-1053TC/-1102TG/-1690GA heterozygotes, and -438AA/-1053TT/-1102TT/-1690GG homozygotes had the lowest TAFI levels (p=0.0003). TAFI concentrations in -152AA/-530CC/-1925TT homozygotes were somewhat higher but not significantly different from levels observed for -152AG/-530CT/-1925TC heterozygotes, Taken in combination, -438AG/-1053TC/-1102TG/-1690GA and -438AA/-1053TT/-1102TT/-1690GG yielded an OR for DVT of 0.8 (95%CI: 0.6-1). in subjects aged < 35 years the OR was 0.7 (95%CI: 0.5-1.1), the OR for -152AG/-530CT/-1925TC was 1 (95%CI: 0.5-2.2) in the whole group of patients and controls, whereas in subjects aged <35 years the OR was 0.1 (95%CI: 0.02-0.9).Interpretation and Conclusions. Polymorphisms in the TAFI promoter determine plasma antigen levels and may influence the risk of venous thrombophilia. <(c)>2001, Ferrata Storti Foundation.

Evaluation of survey methods for sampling anuran species richness in the neotropics.

Species richness is central to ecological theory, with practical applications in conservation, environmental management and monitoring. Several techniques are available for measuring species richness and composition of amphibians in breeding pools, but the relative efficacy of these methods for sampling high-diversity Neotropical amphibian fauna is poorly understood. I evaluated seven studies from south and south-eastern Brazil to compare the relative and combined effectiveness of two methods for measuring species richness at anuran breeding pools: acoustic surveys with visual encounter of adults and dipnet surveys of larvae. I also compared the relative efficacy of each survey method in detecting species with different reproductive modes. Results showed that both survey methods underestimated the number of species when used separately; however, a close approximation of the actual number of species in each breeding pool was obtained when the methods were combined. There was no difference between survey methods in detecting species with different reproductive modes. These results indicate that researchers should employ multiple survey methods that target both adult and larval life history stages in order to accurately assess anuran species richness at breeding pools in the Neotropics.