Didactical Framework for the Simulation of Computer Performance Analysis

In this paper, we discussed the main aspects of the various development carried out on the subject of "Operating systems" and "Evaluation systems of data processing" for the degree course in information systems of the FaCENA from the UNNE. Here, emphasis was placed on various algorithms for the analysis of performance in calculation systems. The motivation for the realization of this work is based on the fact that students often encounter difficulties in identifying the formula that should be used in each of the statements of the practical exercises during performance analysis. The proposal aims to provide students with a tool to complement the developed in class. It was a web application designed to encourage the process of teaching - learning, based on an applet that acts as a container in using different interfaces. Each one of them represents the execution of a method of evaluation of performance, including the law of Amdhal, performance, improvement, comparative analysis, operational analysis, workload characterization, and capacity planning. In addition, a web application that allows the self-assessment of student in achieving learning outcomes was developed. The implementation of web application, however, makes use of the b-learning, model of teaching and learning combined, that collects the advantages of the model to distance. It also takes advantage of the importance of the group, the rhythm of learning, and the direct contact with the Professor

In vivo assessment of the impedance ratio method used in electronic foramen locators

<p>Abstract</p> <p>Background</p> <p>The results of an <it>in vivo </it>study on the "ratio method" used in electronic foramen locators (EFL) are presented. EFLs are becoming widely used in the determination of the working length (WL) during the root canal treatment. The WL is the distance from a coronal reference point to the point at which canal preparation and filling should terminate. The "ratio method" was assessed by many clinicians with the aim of determining its ability to locate the apical foramen (AF). Nevertheless, <it>in vivo </it>studies to assess the method itself and to explain why the "ratio method" is able to locate the apical foramen and is unable to determine intermediate distances were not published so far.</p> <p>Methods</p> <p>A developed apparatus applies an electrical current signal with constant amplitude of 10 μA_RMSthrough the endodontic file within the root canal. The applied current signal is composed by summing six sine waves, from 250 Hz to 8 kHz. Data were acquired with the endodontic file tip at 7 different positions within root canals. In the frequency domain the quotients between the amplitude of a reference frequency and the amplitudes of the other frequencies components were calculated. Twenty one root canals were analyzed in vivo, during the endodontic treatment of twelve teeth of different patients, with age between 20 to 55 years.</p> <p>Results</p> <p>For the range of frequencies used in the commercial EFLs and for distances ranging from -3 mm to -1 mm of the AF, the impedance of the root canal is mainly resistive. However, when the file tip gets closer to AF, the root canal electrical impedance starts to change from a mainly resistive to a complex impedance. This change in the measured root canal impedance starts when the file tip is near -1.0 mm from the AF, getting stronger as the file tip gets closer to the AF. This change in the impedance behavior affects the ratio (quotient) of the impedance measured at different frequencies. Through graphic analysis it is demonstrated why EFLs based on the ratio method are unable to accurately measure any distances between - 3.0 and -0.5 mm from the apical foramen. The only reliable measurement is the 0 mm distance, which is when the file tip is at the AF.</p> <p>Conclusions</p> <p>The electrical impedance values of 21 root canals were <it>in vivo </it>studied. The results confirm the ability of EFLs that are based on the ratio method to accurately locate the AF position and explain why they are unable to determine the file tip position along the root canal.</p

Activated carbon from polyurethane residues as molecular sieves for kinetic adsorption/separation of CO2/CH4

Activated carbon-based molecular sieves were synthetized, characterized and their kinetics of adsorption were evaluated to be used in separation processes of CO2/CH4 mixtures. Polyurethane (PU) foams were used as carbon precursors and the PU-derived carbons were physical activated with CO2. All the samples present a preferential adsorption of CO2 over methane in kinetic adsorption experiments. Samples activated at 800 ºC during 6 h exhibited the highest selectivity due to the absence of methane adsorption at lower resident times, which makes those samples very interesting for industrial processes of natural gas purification. Kinetic studies were performed to explain the kinetic profiles obtained, confirming that in the samples with smallest pore size, intraparticle diffusion was the limiting step, evidencing that certain oxygen groups favour CO2 adsorption, whereas adsorption was the limiting step in the samples with wider pores.This research was funded by MINECO (MAT2016-80285-p), GV (PROMETEOII/2014/004), H2020 (MSCA-RISE-2016/NanoMed Project). Financial support from the National Council for Scientific and Technological Development (CNPq-Brazil) is also acknowledged

Reconstruction of complex single-cell trajectories using CellRouter

A better understanding of the cell-fate transitions that occur in complex cellular ecosystems in normal development and disease could inform cell engineering efforts and lead to improved therapies. However, a major challenge is to simultaneously identify new cell states, and their transitions, to elucidate the gene expression dynamics governing cell-type diversification. Here, we present CellRouter, a multifaceted single-cell analysis platform that identifies complex cell-state transition trajectories by using flow networks to explore the subpopulation structure of multi-dimensional, single-cell omics data. We demonstrate its versatility by applying CellRouter to single-cell RNA sequencing data sets to reconstruct cell-state transition trajectories during hematopoietic stem and progenitor cell (HSPC) differentiation to the erythroid, myeloid and lymphoid lineages, as well as during re-specification of cell identity by cellular reprogramming of monocytes and B-cells to HSPCs. CellRouter opens previously undescribed paths for in-depth characterization of complex cellular ecosystems and establishment of enhanced cell engineering approaches

Bioconversion of cassava starch by-product into Bacillus and related bacteria polyhydroxyalkanoates

Background: Unlike petroleum-based synthetic plastics, biodegradable biopolymer generation from industrial residue is a key strategy to reduce costs in the production process, as well as in the waste management, since efficient industrial wastewater treatment could be costly. In this context, the present work describes the prospection and use of bacterial strains capable to bioconvert cassava starch by-product into biodegradable polyhydroxyalkanoates (PHAs). Results: The first step of this study was the bacterial competence screening which was conducted with 72 strains covering 21 Bacillus and related species. The microorganism growth in a medium with a starch substrate was measured by an innovative MTT assay, while the ability of the bacteria to secrete amylase and produce PHA was evaluated by the Nile Red Dye method. Based on growth and potential for PHA production, four isolates were selected and identified as Bacillus megaterium by 16S rRNA sequencing. When cultivated in hydrolyzed cassava starch by-product, maximum production reached 4.97 g dry biomass/L with 29.7% of Poly-(3-hydroxybutyrate) (characterized by FTIR). Conclusions: MTT assay proved to be a reliable methodology for monitoring bacterial growth in insoluble media. Selected amylolytic strains could be used as an alternative industrial process for biodegradable plastics production from starchy residues, reducing costs for biodegradable biopolymer production and wastewater treatment operations

Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient

We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

Conductive TiC/Ti–Cu/C composites fabricated by Ti–Cu alloy reactive infiltration into 3D-printed carbon performs

The microstructure and electrical properties of dense TiC/Ti–Cu/C composites fabricated by pressureless reactive infiltration of Ti–Cu alloy into porous starch-derived carbon preforms prepared by 3D printing was evaluated. Porosities in the range of 65–78 vol% were varied by post-isostatic pressing the as-printed preforms at pressures of 50–400 MPa. The reactive melt infiltration was carried out at 1100℃ in a flowing Ar atmosphere and resulted in formation of a composite comprised predominantly of substoichiometric TiC, binary intermetallic Ti–Cu phases and residual carbon. Scanning electron microscopy analyses revealed a microstructure consisting of dispersed fine-grained TiC in a Ti–Cu matrix surrounded by a continuous carbon phase. Electrical resistivity measurements using the four-probe method were carried out and correlated to the composite microstructure. The electrical resistivity was evaluated in terms of carbon and TiC volume fractions