oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 2 )

2019 ( 92 )

2018 ( 101 )

2017 ( 116 )

Custom range...

Search Results: 1 - 10 of 55623 matches for " David Freire "
All listed articles are free for downloading (OA Articles)
Page 1 /55623
Display every page Item
Enabling Reproducible Science with VisTrails
David Koop,Juliana Freire,Claudio T. Silva
Computer Science , 2013,
Abstract: With the increasing amount of data and use of computation in science, software has become an important component in many different domains. Computing is now being used more often and in more aspects of scientific work including data acquisition, simulation, analysis, and visualization. To ensure reproducibility, it is important to capture the different computational processes used as well as their executions. VisTrails is an open-source scientific workflow system for data analysis and visualization that seeks to address the problem of integrating varied tools as well as automatically documenting the methods and parameters employed. Growing from a specific project need to supporting a wide array of users required close collaborations in addition to new research ideas to design a usable and efficient system. The VisTrails project now includes standard software processes like unit testing and developer documentation while serving as a base for further research. In this paper, we describe how VisTrails has developed and how our efforts in structuring and advertising the system have contributed to its adoption in many domains.
Application of 3A Zeolite Prepared from Venezuelan Kaolin for Removal of Pb (II) from Wastewater and Its Determination by Flame Atomic Absorption Spectrometry  [PDF]
Wendy Rondón, David Freire, Zully de Benzo, Angela B. Sifontes, Yorbin González, Maribel Valero, Joaquín L. Brito
American Journal of Analytical Chemistry (AJAC) , 2013, DOI: 10.4236/ajac.2013.410069
Abstract:

This work consists in the use of a 3A zeolite (K-LTA) obtained by a process of exchange of sodium for potassium (4A zeolite), synthesized from Venezuelan kaolin for the removal of Pb (II) ions from aqueous solutions by batch process mode in order to consider its application in treating industrial wastewaters. The 3A zeolite was characterized for X-ray powder diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy and energy dispersive X-ray microanalysis (SEM-EDX). The metal concentration in the equilibrium Ce (mg·L-1) after adsorption with 3A zeolite was analyzed using flame atomic absorption spectrometry (FAAS). The influences of the solution pH, contact time, metal initial concentration and adsorbent dosage have been studied. The retention of metal occurring at pH values around 6.5 and the adsorption equilibrium was obtained at 60 min. The equilibrium process was well described by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The Langmuir parameters qm (mg·g-1) and b (L·mg-1) (which are related to the sorption capacity and constant of sorption energy) obtained were 14.64 and 5.42 respectively. The Pb (II) experimental uptake was about 14.56 mg·g-1, a little smaller than the theoretical one given by Langmuir isotherm model. The

Biological Template Based on ent-Kaurane Diterpenoid Glycosides for the Synthesis of Inorganic Porous Materials  [PDF]
ángela B. Sifontes, Mirla Rodriguez, David Freire, Wendy Rondón, Ligia Llovera, Edgar Ca?izales, Franklin J. Méndez, Andrea Monaco, Yraida Díaz
Advances in Chemical Engineering and Science (ACES) , 2013, DOI: 10.4236/aces.2013.34035
Abstract: Recent studies on the preparation of porous nano-materials revealed that the use of kaurane diterpenoids molecules from steviol as biological template favors the obtaining of metallic oxides with tubular morphology as nanorods or nanofibers. In this sense, the present contribution shows an analysis in order to understand how these glycosides of kaurane diterpenoids control the nucleation and growth of inorganic materials favoring the obtaining of these morphologies. For this purpose, it was necessary to carry out studies of the leaf aqueous extract of Stevia rebaudiana by HRTEM, FTIR and 1H-NMR.
Effects of Light Emitting Diode in Erythrocytes  [PDF]
Hennes Gentil de Araújo, Patricia Froes Meyer, Mario Bernardo Filho, éric Heleno Freire Frederico, Sebasti?o David dos Santos Filho, Marcus Vinicius de Mello Pinto
Modern Research in Inflammation (MRI) , 2014, DOI: 10.4236/mri.2014.33015
Abstract:

The Light Emitting Diode (LED) is a phototherapy equipment, poorly studied, which is able of acting on blood level and it has frequently appeared in clinical practice of physiotherapy to aid on skin rejuvenation, control inflammation and wound healing. The aim of the study was to evaluate the effects of LED on red blood cells through the spectrophotometer. This is an experimental study with a sample of 5 male Wistar rats weighting between 200 g and 350 g, randomly selected, anesthetized and 4 ml of blood was collected by cardiac puncture. The blood collected was divided into four groups, one control and three treated, these individually irradiated by blue LED (420 - 490 nm), green LED (515 - 570 nm) and red LED (620 - 680 nm) at an output of 3 watts, for 10 minutes and 5 cm apart from the surface of the blood, then it was analyzed by a spectrophotometer at 540 nm. The results were submitted to Anova and Post-roch Turkey (p < 0.05). All wavelengths tested produced hemolysis greater than the control in hypotonic solutions of NaCl (range 0.02 to 0.06 M) (p < 0.01). Only the band between 515 - 570 nm provides a higher hemolysis (range 0.06 to 0.1) when compared to the control group (p < 0.05). The irradiation of blood through the LED therapy was able to weaken the cell membrane of the red blood cells. It is likely that hemolysis does not bring harm the body, because as it is a local therapy, the amount of hemolysis that can be caused is small and it will induce the reproduction of new red blood cells, thus improving their physiological functions.

The Quantum Unconscious and the Observant Consciousness  [PDF]
Rui Freire Lucas
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.76087
Abstract:

Based on the philosophy of Henri Bergson and the contemporary developments of Quantum Physics, I sought to demonstrate how these developments are incompatible with a positivist vision of reality, which is still influential in the scientific community. Specifically, in the field of Psychoanalysis, I have shown how this outdated epistemology has been responsible for a manic denial of the theories of Carl Gustav Jung and Wilfred Bion (later stage) as part of an immobilising allegiance to a schizo-paranoid functional tradition imposed by its founder. Finally, I have proposed that supported by the formulations of these renegade analysts, psychoanalysis can progress to a depressive position, eventually transmitting this integrated perspective of reality to the rest of the scientific community and postmodern society in general.

Antimicrobial activity and chemical composition of essential oil of Pelargonium odoratissimum
Andrade, Milene A.;Cardoso, Maria G.;Batista, Luís R.;Freire, Juliana M.;Nelson, David L.;
Revista Brasileira de Farmacognosia , 2011, DOI: 10.1590/S0102-695X2011005000009
Abstract: the chemical composition of the essential oil from the leaves of pelargonium odoratissimum (l.) l'hér., geraniaceae, was determined and the antimicrobial activities against the aspergillus flavus cml 1816, aspergillus carbonarius cml1815 and aspergillus parasiticus cmla 817 fungi, as well the staphylococcus aureus atcc 25923 and escherichia coli atcc 25 992 bacteria were evaluated. the essential oil was isolated by steam distillation using a modified clevenger apparatus, and its constituents were identified and quantified by gc/ms and gc-fid analyses. in vitro bioanalytical testing was performed using a completely randomized design. the concentrations of essential oil employed ranged from 0.1 to 2 μl.ml-1 (in dimethyl sulfoxide) for the fungus species and from 1 to 500 μl.ml-1 for the bacteria. the diameters of the inhibition zones formed for bacteria and the mean diameters of mycelial growth in perpendicular directions for fungi were measured, followed by calculation of the percentage of inhibition. the essential oil from the leaves of p. odoratissimum furnished methyleugenol (96.80%), a phenylpropanoid. this essential oil inhibited the growth of fungi (100% inhibition) and exhibited a small effect on the bacteria at the concentrations tested.
Dot1-Dependent Histone H3K79 Methylation Promotes Activation of the Mek1 Meiotic Checkpoint Effector Kinase by Regulating the Hop1 Adaptor
David Ontoso,Isabel Acosta,Fred van Leeuwen,Raimundo Freire,Pedro A. San-Segundo
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003262
Abstract: During meiosis, accurate chromosome segregation relies on the proper interaction between homologous chromosomes, including synapsis and recombination. The meiotic recombination checkpoint is a quality control mechanism that monitors those crucial events. In response to defects in synapsis and/or recombination, this checkpoint blocks or delays progression of meiosis, preventing the formation of aberrant gametes. Meiotic recombination occurs in the context of chromatin and histone modifications, which play crucial roles in the maintenance of genomic integrity. Here, we unveil the role of Dot1-dependent histone H3 methylation at lysine 79 (H3K79me) in this meiotic surveillance mechanism. We demonstrate that the meiotic checkpoint function of Dot1 relies on H3K79me because, like the dot1 deletion, H3-K79A or H3-K79R mutations suppress the checkpoint-imposed meiotic delay of a synapsis-defective zip1 mutant. Moreover, by genetically manipulating Dot1 catalytic activity, we find that the status of H3K79me modulates the meiotic checkpoint response. We also define the phosphorylation events involving activation of the meiotic checkpoint effector Mek1 kinase. Dot1 is required for Mek1 autophosphorylation, but not for its Mec1/Tel1-dependent phosphorylation. Dot1-dependent H3K79me also promotes Hop1 activation and its proper distribution along zip1 meiotic chromosomes, at least in part, by regulating Pch2 localization. Furthermore, HOP1 overexpression bypasses the Dot1 requirement for checkpoint activation. We propose that chromatin remodeling resulting from unrepaired meiotic DSBs and/or faulty interhomolog interactions allows Dot1-mediated H3K79-me to exclude Pch2 from the chromosomes, thus driving localization of Hop1 along chromosome axes and enabling Mek1 full activation to trigger downstream responses, such as meiotic arrest.
Constraining the Bulk Properties of Dense Matter by Measuring Millisecond Pulsar Masses - A White Paper for the Astronomy and Astrophysics Decadal Survey, CFP Panel
Paulo C. Freire,David Nice,James Lattimer,Ingrid Stairs,Zaven Arzoumanian,James Cordes,Julia Deneva
Physics , 2009,
Abstract: More than four decades after the discovery of pulsars, the composition of matter at their cores is still a mystery. This white paper summarizes how recent high-precision measurements of millisecond pulsar masses have introduced new experimental constraints on the properties of super-dense matter, and how continued timing of intriguing new objects, coupled with radio telescope surveys to discover more pulsars, might introduce significantly more stringent constraints.
Avalia??o da reprodutibilidade da tomografia computadorizada no estadiamento da pancreatite aguda
Freire Filho, Edison de Oliveira;Shigueoka, David Carlos;Bekhor, Daniel;Vieira, Renata La Rocca;Yamada, André Fukunishi;Freire, Maxime Figueiredo de Oliveira;Ajzen, Sergio;D'Ippolito, Giuseppe;
Radiologia Brasileira , 2007, DOI: 10.1590/S0100-39842007000600006
Abstract: objective: to evaluate the reproducibility of unenhanced and contrast-enhanced computed tomography in the assessment of patients with acute pancreatitis. materials and methods: fifty-one unenhanced and contrast-enhanced abdominal computed tomography studies of patients with acute pancreatitis were blindly reviewed by two radiologists (observers 1 and 2). the morphological index was separately calculated for unenhanced and contrast-enhanced computed tomography and the disease severity index was established. intraobserver and interobserver reproducibility of computed tomography was measured by means of the kappa index (k). results: interobserver agreement was k = 0.666, 0.705, 0.648, 0.547 and 0.631, respectively for unenhanced and contrast-enhanced morphological index, presence of pancreatic necrosis, pancreatic necrosis extension, and disease severity index. intraobserver agreement (observers 1 and 2, respectively) was k = 0.796 and 0.732 for unenhanced morphological index; k = 0.725 and 0.802 for contrast-enhanced morphological index; k = 0.674 and 0.849 for presence of pancreatic necrosis; k = 0.606 and 0.770 for pancreatic necrosis extension; and k = 0.801 and 0.687 for disease severity index at computed tomography. conclusion: computed tomography for determination of morphological index and disease severity index in the staging of acute pancreatitis is a quite reproducible method. the absence of contrast-enhancement does not affect the computed tomography morphological index reproducibility.
On the Influence of Particles Characteristics on Moisture Diffusivity during Drying of Granular Porous Media  [PDF]
José Teixeira Freire, Fábio Bentes Freire, Hugo Perazzini
Advances in Chemical Engineering and Science (ACES) , 2014, DOI: 10.4236/aces.2014.41002
Abstract:

The objective of this work was to study the diffusive mechanisms of mass transfer predominant in the drying of cylindrical unconsolidated granular porous media of different diameters of porous spherical particles. The experimental study was based on determining the drying kinetics of the porous media evaluated and on obtaining the physical properties regarding the particles that constitute them. Moisture data as a function of time were obtained by subjecting the porous media to an upward single-phase flow of heated air at a specific condition of temperature, velocity and absolute humidity of the drying air. The theoretical study regarded the determination of the overall effective diffusion coefficient based on mass transfer foundations. From the results obtained, it was verified that the drying kinetics, for a given operational condition applied, is influenced by particle diameter, and the effective superficial liquid diffusivity is the mechanism that limits the drying process.

Page 1 /55623
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.