Optimal mean-variance control for discrete-time linear systems with Markovian jumps and multiplicative noises

In this paper, we consider the stochastic optimal control problem of discrete-time linear systems subject to Markov jumps and multiplicative noises under two criteria. The first one is an unconstrained mean-variance trade-off performance criterion along the time, and the second one is a minimum variance criterion along the time with constraints on the expected output. We present explicit conditions for the existence of an optimal control strategy for the problems, generalizing previous results in the literature. We conclude the paper by presenting a numerical example of a multi-period portfolio selection problem with regime switching in which it is desired to minimize the sum of the variances of the portfolio along the time under the restriction of keeping the expected value of the portfolio greater than some minimum values specified by the investor. (C) 2011 Elsevier Ltd. All rights reserved.

Evaluation of Complete Denture Quality and Masticatory Efficiency in Denture Wearers

Purpose: This study aimed to investigate (1) the influence of complete denture quality and years of denture use on masticatory efficiency and (2) the relationship between complete denture quality and years of use. Materials and Methods: A cross-sectional study was conducted with 93 edentulous patients (mean age: 65.6 years) wearing both mandibular and maxillary dentures. Patients were classified into two categories according to years of denture use: <= 2 years and >= 5 years. Masticatory efficiency was evaluated via the colorimetric method with beads as the artificial test food. A reproducible method for objective evaluation of the technical quality of complete dentures was employed. The association between denture quality and years of denture use was analyzed using chi-square and Fisher exact tests. The results of masticatory efficiency testing were analyzed using two-way analysis of variance (with the Tukey post hoc test) in terms of years of denture use <= 2 years, >= 5 years) and denture quality (poor, average, good). Results: A significant relationship was found between denture quality and years of denture use (P < .05). Masticatory efficiency differed significantly (P < .05) between patients with <= 2 years of denture use (0.101 +/- 0.076 absorbance) and >= 5 years of use (0.068 +/- 0.076 absorbance). Masticatory efficiency was not influenced by denture quality. Conclusions: Complete denture quality and masticatory efficiency significantly decreased over time. However, complete denture quality did not influence masticatory efficiency. Int J Prosthodont 2012;25:625-630.

Kinetic and growth parameters of Arthrospira (Spirulina) platensis cultivated in tubular photobioreactor under different cell circulation systems

Arthrospira platensis was cultivated in tubular photobioreactor in order to evaluate growth and biomass production at variable photosynthetic photon flux density (PPFD?=?60, 120, and 240?mu mol photons m-2?s-1) and employing three different systems for cell circulation, specifically an airlift, a motor-driven pumping and a pressurized system. The influence of these two independents variables on the maximum cell concentration (Xm), cell productivity (Px), nitrogen-to-cell conversion factor (YX/N), photosynthetic efficiency (PE), and biomass composition (total lipids and proteins), taken as responses, was evaluated by analysis of variance. The statistical analysis revealed that the best combination of responses' mean values (Xm?=?4,055?mg?L-1, Px?=?406?mg?L-1?day-1, YX/N?=?5.07?mg?mg-1, total lipids?=?8.94%, total proteins?=?30.3%, PE?=?2.04%) was obtained at PPFD?=?120?mu mol photons m-2?s-1; therefore, this light intensity should be considered as the most well-suited for A. platensis cultivation in this photobioreactor configuration. The airlift system did not exert any significant positive statistical influence on the responses, which suggests that this traditional cell circulation system could successfully be substituted by the others tested in this work. Biotechnol. Bioeng. 2012; 109:444450. (c) 2011 Wiley Periodicals, Inc.

Effects of an adapted physical activity program on the physical condition of elderly women: an analysis of efficiency

Background: Specific research tools and designs can assist in identifying the efficiency of physical activity in elderly women. Objectives: To identify the effects of physical activity on the physical condition of older women. Method: A one-year-long physical activity program (123 sessions) was implemented for women aged 60 years or older. Four physical assessments were conducted, in which weight, height, BMI, blood pressure, heart rate, absences, grip strength, flexibility, VO2max, and static and dynamic balance were assessed. The statistical analyses included a repeated measures analysis, both inferential (analysis of variance - ANOVA) and effect size (Cohen's d coefficient), as well as identification of the participants' efficiency (Data Envelopment Analysis - DEA). Results: Despite the observation of differences that depended on the analysis used, the results were successful in the sense that they showed that physical activity adapted to older women can effectively change the decline in physical ability associated with aging, depending on the purpose of the study. The 60-65 yrs group was the most capable of converting physical activity into health benefits in both the short and long term. The >65 yrs group took less advantage of physical activity. Conclusions: Adherence to the program and actual time spent on each type of exercise are the factors that determine which population can benefit from physical activity programs. The DEA allows the assessment of the results related to time spent on physical activity in terms of health concerns. Article registered in Clinicaltrials.gov under number NCT01558401.

Masticatory efficiency in class II and class III dentofacial deformities

Masticatory efficiency may be impaired in individuals with dentofacial deformities. The objective of the present study was to determine the condition of masticatory efficiency in individuals with dentofacial deformities. 30 patients with class II (DG-II) and 35 patients with class III (DG-III) dentofacial deformity participated in the study, all had an indication for orthognathic surgery. 30 volunteers (CG) with no alterations of facial morphology or dental occlusion and with no signs or symptoms of temporomandibular joint dysfunction also participated. Masticatory efficiency was analysed using a bead system (colorimetric method). Each individual chewed 4 beads, one at a time, over 20 s measured with a chronometer. The groups were compared in term's of masticatory efficiency using analysis of variance (ANOVA), with the level of significance set at P < 0.05. Masticatory efficiency was significantly greater in CG (P < 0.05) than in DG-II and DG-III in all chewing tasks tested, with no significant difference between DG-II and DG-III (P > 0.05). It was observed that the presence of class II and class III dentofacial deformity affected masticatory efficiency compared to CG, although there was no difference between DG-II and DG-III.

Variance Effective Population Size for Dioecious Species

The concept of effective population size (N(e)) is an important measure of representativeness in many areas. In this research, we consider the statistical properties of the number of contributed gametes under practical situations by adapting Crow and Denninston's (1988) N(e) formulas for dioecious species. Three sampling procedures were considered. In all circumstances, results show that as the offspring sex ratio (r) deviates from 0.5, N(e) values become smaller, and the efficiency of gametic control for increasing N(e) is reduced. For finite populations, where all individuals are potentially functional parents, the reduction in N(e) due to an unequal sex ratio can be compensated for through female gametic control when 0.28 <= r <= 0.72. This outcome is important when r is unknown. When only a fraction of the individuals in a population is taken for reproduction, N(e) is meaningful only if the size of the reference population is clearly defined. Gametic control is a compensating factor in accession regeneration when the viability of the accession is around 70 or 75%. For germ-plasm collection, when parents are a very small fraction of the population, maximum N(e) will be approximately 47 and 57% of the total number of offspring sampled, with female gametic control, r varying between 0.3 and 0.5, and being constant over generations.