Hartley-Ross Type Unbiased Estimators Using Ranked Set Sampling and Stratified Ranked Set Sampling

This paper proposes several Hartley-Ross (HR) type unbiased estimators of the finite population mean using information on known population parameters of the auxiliary variable in ranked set sampling (RSS) and stratified ranked set sampling (StRSS). The variances of the proposed HR unbiased ratio-type estimators are obtained to first degree of approximation. In simulation study the proposed estimators are more efficient as compared to all other competitor estimators

Understanding the clinical spectrum of complicated Plasmodium vivax malaria: a systematic review on the contributions of the Brazilian literature

The resurgence of the malaria eradication agenda and the increasing number of severe manifestation reports has contributed to a renewed interested in the Plasmodium vivax infection. It is the most geographically widespread parasite causing human malaria, with around 2.85 billion people living under risk of infection. The Brazilian Amazon region reports more than 50% of the malaria cases in Latin America and since 1990 there is a marked predominance of this species, responsible for 85% of cases in 2009. However, only a few complicated cases of P. vivax have been reported from this region. A systematic review of the Brazilian indexed and non-indexed literature on complicated cases of vivax malaria was performed including published articles, masters' dissertations, doctoral theses and national congresses' abstracts. The following information was retrieved: patient characteristics (demographic, presence of co-morbidities and, whenever possible, associated genetic disorders); description of each major clinical manifestation. As a result, 27 articles, 28 abstracts from scientific events' annals and 13 theses/dissertations were found, only after 1987. Most of the reported information was described in small case series and case reports of patients from all the Amazonian states, and also in travellers from Brazilian non-endemic areas. The more relevant clinical complications were anaemia, thrombocytopaenia, jaundice and acute respiratory distress syndrome, present in all age groups, in addition to other more rare clinical pictures. Complications in pregnant women were also reported. Acute and chronic co-morbidities were frequent, however death was occasional. Clinical atypical cases of malaria are more frequent than published in the indexed literature, probably due to a publication bias. In the Brazilian Amazon (considered to be a low to moderate intensity area of transmission), clinical data are in accordance with the recent findings of severity described in diverse P. vivax endemic areas (especially anaemia in Southeast Asia), however in this region both children and adults are affected. Finally, gaps of knowledge and areas for future research are opportunely pointed out

Improved Ratio-type Estimators of Population Mean In Ranked Set Sampling Using Two Concomitant Variables

In this paper, we propose an efficient class of ratio-in-exponential-type estimators with two concomitant variables using Ranked Set Sampling (RSS) scheme which improves the available estimators. The biases and mean square errors (MSEs) of the proposed estimators are obtained up to first degree approximation. Comparisons among the proposed and competitor estimators are made both theoretically and through simulation study. It turned out that when the variable of interest and the concomitant variables jointly followed a trivariate Gamma distribution, the proposed class of estimators dominates all other competitor estimators

An Ecient Class of Estimators of Population Mean in Two-Phase Sampling Using Two Auxiliary Variables

This study is devoted to obtain an ecient estima-tor for population mean in two-phase sampling using two auxiliary variables following Vishwakarma and Kumar (2014). Expressions for bias and mean squared error(MSE) are obtained to rst or-der of approximation. The new proposed estimator is compared with some competitor estimators both theoretically and numeri-cally using eight dierent data sets. It has been shown that the new proposed estimator gives more ecient results as compared to its competitor estimators

Production of polymer-bioactive glass nanocomposites for bone repair and substitution

Bioactive glass (BG) is a well suited biomaterial for bone and tissue regeneration. BG is capable of generating strong chemical interactions with the surrounding bone tissue and, by forming a calcium phosphate layer when exposed to physiological fluids, can promote osteointegration. Also, the ionic release from BG may stimulate gene expression and, thus, osteoinduction. Still, its use in biomedicine is limited by its poor mechanical performance. The combination with biodegradable polymers to form composites that explore the flexibility of these materials with the stiffness and bioactive character of the BG has opened a window to many more uses. Both synthetic and natural origin polymers have been combined with BG nanoparticles/nanofibers with successful outcomes. BG–polymer nanocomposites mimic more closely the structure of natural bone. In the present chapter we will enumerate the most promising BG–polymer combinations and the advantages introduced in bone regeneration by these composites, and will explore some of the most commonly used synthesis techniques applied to the production of BG–polymer composites.FCT, FEDER and POC