Advancing open education policy in Brazilian higher education

Faculdade de Educação (FE)Departamento de Métodos e Técnicas (FE MTC

Enhancement of Optical Coherence Tomography Images of the Retina by Normalization and Fusion

This paper describes an image processing method applied to Optical Coherence Tomography (OCT) images of the retina. The aim is to achieve improved OCT images from the fusion of sequential OCT scans obtained at identical retinal locations. The method is based on the normalization of the acquired images and their fusion. As a result, a noise reduction and an image enhancement are reached. Thanks to the resulting improvement in retinal imaging, clinical specialists are able to evaluate more efficiently eyes pathologies and anomalies. This paper presents the proposed method and gives some evaluation results

Nanoparticle formation of chitosan induced by 4-sulfonatocalixarenes: utilization for alkaloid encapsulation

Spontaneous formation of positively charged nanoparticles was observed upon mixing more than stoichiometric amount of chitosan with 4-sulfonatocalix[8]arene (SCX8) in acidic solution. The particle size did not change with SCX8 concentration, polymer chain length, and the degree of deacetylation at 0.002 ≤ SCX8/chitosan ≤0.043 molar ratios in 0.01 M HCl. However, larger aggregates were produced when chitosan concentration was increased. The most stable nanoparticles with 160 nm diameter and narrow size distribution were obtained at pH 4 using low molecular weight chitosan. These particles encapsulated coralyne with more than 90 % entrapment efficiency and 15 % loading capacity. A loading ratio of [coralyne]/[SCX8] = 1.7 was achieved without any stability loss. 4-Sulfonatocalix[4]arene induced the formation of slightly smaller nanoparticles than its homologs comprising 6 or 8 phenol units. © 2016, Springer-Verlag Berlin Heidelberg

4-Sulfonatocalixarene-induced nanoparticle formation of methylimidazolium-conjugated dextrans: Utilization for drug encapsulation

Methylimidazolium side groups were grafted via ether linkage to dextran and the self-assembly of these polymers with 4-sulfonato-calix[n]arenes (SCXn) was studied in aqueous solutions. Dynamic light scattering and zeta potential measurements revealed the mixing ratio ranges of the constituents where stable nanoparticles could be created. The macrocycle size of SCXn and the molecular mass of the polymer barely affected the nanoparticle diameter, but the lowering of the imidazolium degree of substitution substantially diminished the stability of the associates. The pH change from neutral to acidic also unfavourably influenced the self-organization owing mainly to the decrease of the SCXn charge. Cryogenic transmission electron microscopy images proved the spherical morphology of the nanoproducts in which the stoichiometry of the constituents was always close to the one corresponding to charge compensation. The flexible and positively charged dextran-chains are compacted by the polyanionic SCXn. Coralyne, a pharmacologically important alkaloid was efficiently embedded by self-assembly in the produced nanoparticles reaching 99% association efficiency. © 2019 Elsevier Lt

Effects of counterion fluctuations in a polyelectrolyte brush

We investigate the effect of counterion fluctuations in a single polyelectrolyte brush in the absence of added salt by systematically expanding the counterion free energy about Poisson-Boltzmann mean field theory. We find that for strongly charged brushes, there is a collapse regime in which the brush height decreases with increasing charge on the polyelectrolyte chains. The transition to this collapsed regime is similar to the liquid-gas transition, which has a first-order line terminating at a critical point. We find that for monovalent counterions the transition is discontinuous in theta solvent, while for multivalent counterions the transition is generally continuous. For collapsed brushes, the brush height is not independent of grafting density as it is for osmotic brushes, but scales linear with it.Comment: 9 pages, 9 figure

The Super Star Cluster NGC 1569-A Resolved on Sub-Parsec Scales with Hubble Space Telescope Spectroscopy

We present 3000--10000 Ang HST/STIS long-slit spectroscopy of the bright super star cluster A (SSC-A) in the dwarf starburst galaxy NGC 1569. The 0.05" HST angular resolution allows, for the first time, to probe for spatial variations in the stellar population of a ~ 10^6 M_sun SSC. Integrated ground-based spectra of SSC-A have previously revealed young Wolf-Rayet (WR) signatures that coexist with features from supposedly older, red supergiant (RSG), populations. We find that the WR emission complexes come solely from the subcluster A2, identified in previous HST imaging, and are absent from the main cluster A1, thus resolving the question of whether the WR and RSG features arise in a single or distinct clusters. The equivalent widths of the WR features in A2 --- including the CIV 5808 complex which we detect in this object for the first time --- are larger than previously observed in other WR galaxies. Models with sub-solar metallicity, as inferred from the nebular emission lines of this galaxy, predict much lower equivalent widths. On the ``clean'' side of A1, opposite to A2, we find no evidence for radial gradients in the observed stellar population at 0.05"<R<0.40" (~0.5 to 5 pc), neither in broad-band, low-resolution, spectra nor in medium-resolution spectra of the infrared CaII triplet.Comment: 5 pages, accepted for publication in ApJ Le

Impact of Knowledge and Attitude on Preventive Practice Regarding Dengue Fever among Residents in Dasmariñas City, Cavite: A Structural Equation Modelling Approach

Dengue has been considered one of the major health problems in the world. Philippines is one of the most affected countries of this epidemic disease during the year 2015. Dasmariñas City is one of the cities in the Philippines affected by dengue fever outbreak. This study aims to assess the current level and to identify the relationships between knowledge, attitude and preventive practice about dengue fever of the respondents within Dasmariñas City, Cavite. This study used purposive sampling in selecting respondents from ten barangays with the highest number of dengue cases during the year 2015. Survey questionnaires was used to gather information from 419 respondents about their demographic profile, involvement in health promotion and educational intervention, sources of information, knowledge, attitude, and preventive practice regarding dengue fever. The results of this study showed that most of the respondents have moderate knowledge level, positive attitude, and fair preventive practices. Preventive practice has a significant relationship with barangay, family income, health promotional activities and educational intervention, and received information. A structural equation model was developed, tested and fitted to the data well (chi-square= 81.960, df= 52, CFI= .947, TLI=.933, and RMSEA= .037). Furthermore, a positive attitude towards dengue fever had a positive impact on the dengue preventive practice of the residents in Dasmariñas, however high knowledge about dengue fever does not guarantee good practice of preventive measures

Model Uncertainty in Ecological Criminology: An Application of Bayesian Model Averaging With Rural Crime Data

In this study we explore the use of Bayesian model averaging (BMA) to address model uncertainty in identifying the determinants of Midwestern rural crime rates using county level data averaged over 2006-07-08. The empirical criminology literature suffers from serious model uncertainty: theory states that everything matters and there are multiple ways to measure key variables.By using the BMA approach we identify variables that appear to most consistently influence rural crime patterns. We find that there are several variables that rise to the top in explaining different types of crime as well as numerous variables that influence only certain types of crime