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Search Results: 1 - 10 of 485770 matches for " Juan A.; "
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The Poisson Distribution Is Applied to Improve the Estimation of Individual Cell and Micropopulation Lag Phases  [PDF]
Juan x Juan Aguirre, Carmen Bravo, Juan A. Ordó?ez, Gonzalo García de Fernando
Advances in Microbiology (AiM) , 2012, DOI: 10.4236/aim.2012.22020
Abstract: Many articles dealing with individual cell lag phase determination assume that growth, when observed, comes from one cell. This assumption is not in agreement with the Poisson distribution, which uses the probability of growth in a sample to predict how many samples contain one, two, or some other number of cells. This article analyses and compares different approaches to improve the accuracy of lag phase estimation of individual cells and micropopulations. It argues that if the highest initial load, as predicted by the Poisson distribution, is assigned to the sample with the shortest lag phase, the second highest to the sample with the second shortest lag phase and so on, the resulting lag phase distributions would be more accurate. This study also proposes the use of a robust test, permutation test, to compare lag phase distributions obtained in different situations.
Influence of H-Type and L-Type Activated Carbon in the Photodegradation of Methylene Blue and Phenol under UV and Visible Light Irradiated TiO2  [PDF]
Juan Matos, Karina Quintana, Andreina García
Modern Research in Catalysis (MRC) , 2012, DOI: 10.4236/mrc.2012.11001
Abstract: Photodegradation of methylene blue (MB) and phenol (Ph) on TiO2 in presence of H-type and L-type activated carbons (AC) was studied. Photodegradation of MB and Ph were studied under two different lamps and results were compared against those obtained on a commercial TiO2. Apparent first order rate constant for the degradation of MB was higher in presence of any AC in comparison of TiO2 alone while only in presence of ACco2-800phenol was photodegradated in shorter irradiation time than that required by TiO2. It can be concluded that TiO2 enhances its photoactivity by a factor up to 8.7 in the degradation of MB in presence of AC and this effect is associated to the specific surface properties of AC.
Future Changes in Drought Characteristics over Southern South America Projected by a CMIP5 Multi-Model Ensemble  [PDF]
Olga C. Penalba, Juan A. Rivera
American Journal of Climate Change (AJCC) , 2013, DOI: 10.4236/ajcc.2013.23017

The impact of climate change on drought main characteristics was assessed over Southern South America. This was done through the precipitation outputs from a multi-model ensemble of 15 climate models of the Coupled Model Intercomparison Project Phase 5 (CMIP5). The Standardized Precipitation Index was used as a drought indicator, given its temporal flexibility and simplicity. Changes in drought characteristics were identified by the difference for early (2011-2040) and late (2071-2100) 21st century values with respect to the 1979-2008 baseline. In order to evaluate the multi-model outputs, model biases were identified through a comparison with the drought characteristics from the Global Precipitation Climatology Centre database for the baseline period. Future climate projections under moderate and high-emission scenarios showed that the occurrence of short-term and long-term droughts will be more frequent in the 21st century, with shorter durations and greater severities over much of the study area. These changes in drought characteristics are independent on the scenario considered, since no significant differences were observed on drought changes. The future changes scenario might be even more dramatic, taking into account that in most of the region the multi-model ensemble tends to produce less number of droughts, with higher duration and lower severity. Therefore, drought contingency plans should take these results into account in order to alleviate future water shortages that can have significant economic losses in the agricultural and water resources sectors of Southern South America.

eHealth Management Platform for Screening and Prediction of Down’s Syndrome in the Republic of Panama  [PDF]
Juan Salda?a, Miguel Vargas-Lombardo
E-Health Telecommunication Systems and Networks (ETSN) , 2014, DOI: 10.4236/etsn.2014.33005
Abstract: Through engineering projects, we have integrated software engineering, geographical information systems and HL7 standard to propose a model of an eHealth management platform for Down’s syndrome screening, replicable in all the country. It will use real time sample information acquired from the local population and will geographically reference this information in the territory of Panama for future research.
Alpha Centauri System and Meteorites Origin  [PDF]
Gustavo V. López, Juan A. Nieto
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.611199
Abstract: We propose a mathematical model for determining the probability of meteorite origin, impacting the earth. Our method is based on axioms similar to both the complex networks and emergent gravity. As a consequence, we are able to derive a link between complex networks and Newton’s gravity law, and as a possible application of our model we discuss several aspects of the Bacubirito meteorite. In particular, we analyze the possibility that the origin of this meteorite may be alpha Centauri system. Moreover, we find that in order for the Bacubirito meteorite to come from alpha Cen and be injected into our Solar System, its velocity must be reduced one order of magnitude of its ejected scape velocity from alpha Cen. There are several ways how this could happened, for example through collision with the Oort cloud objects (located outside the boundary of our Solar System), and/or through collisions within the Solar meteorites belt (located between Mars and Jupiter). We also argue that it may be interesting to study the Bacubirito meteorite from the perspective of the recently discovered Oumuamua object.
Calculus for Coloring  [PDF]
Sergio A. David, Carlos A. Valentim Jr., Juan L. Linares
Creative Education (CE) , 2013, DOI: 10.4236/ce.2013.44037

Professors who administer the differential and integral calculus classes in the hard sciences courses and in the most diverse kinds of engineering, not rarely, are faced by the lack of motivation to learning and difficulties in absorbing the concepts of the discipline. With the purpose of contributing to the teaching-learning process related to calculus classes, this paper looks for synthesizing a process of elaboration and trial of an artwork destined for coloring, which content is specifically related to the discipline “Calculus with Applications IV”, from the Biosystems Engineering course, of the University of Sao Paulo (USP)-Brazil. The material, always prepared in the form of pairs of pages, one displaying the picture to be colored (the artwork) and the other one like its twin (the text), was individually rated by the apprentices students. The obtained results point to the possibility of facing the paradigm and showing that projects like “calculus for coloring” are not only possible, but also a quality complement in the learning-teaching process.

Contribution of the Immigrant Population to Demographic and Spatial Dynamics of the Basque Country  [PDF]
Juan Ramón Murua, Bego?a Eguía
Natural Science (NS) , 2015, DOI: 10.4236/ns.2015.77038
Abstract: The twenty-first century begins with a rupture of the migratory pattern in the Basque Country, a region located in the north of Spain, transforming it from a community which exports its population to one which receives it. Despite the current economic crisis, the Basque Country continues to be a destination for foreigners, now in many cases coming from other Spanish regions most affected by this crisis. Given the quantitative and qualitative importance of these migration flows, in this research we analyze the contribution of immigrants to the demographic dynamics of the Basque Country. By also identifying their patterns of spatial localization, we examine their contribution to the correction or accentuation of regional imbalances in the population distribution. The results reveal that the demographic recovery rests primarily on contributions of this immigrant population, a population which also promotes the rejuvenation of an aging society, although it is far from correcting regional imbalances and may contribute to accentuating them.
The Consequences of a Forced Migration: The Return Home of WWII American Veterans  [PDF]
Isabel María García Conesa, Antonio Daniel Juan Rubio
Advances in Historical Studies (AHS) , 2016, DOI: 10.4236/ahs.2016.51004
Abstract: The end of the Second World War was a serious problem of rehabilitation, not only for the country but also for the huge mass of veterans returning home after the military conflict. And in order to avoid the unrest and social tension that followed the First World War, the US administration sled firstly by President Franklin D. Roosevelt and secondly by Harry Truman were commissioned to design a specific plan for rehabilitation and reintegration to civilian life of veterans. The Service Readjustment Act of 1944, informally known as the G. I. Bill, was an important law that provided a range of benefits for returning veterans of World War II. This law was passed in June 1944 in the United States, turning further into Public Law 78-346, being available to all veterans who served on active duty during the war years. Maybe it was the most representative and striking measure of the many related ones which were rushed by the US administration. Throughout this article we will focus primarily on the major consequences or repercussions that the adoption of the various measures undertaken had on American society in the late 40s, especially after the return home of the Second World War veterans.
Randomness and Topological Invariants in Pentagonal Tiling Spaces
Juan García Escudero
Discrete Dynamics in Nature and Society , 2011, DOI: 10.1155/2011/946913
Abstract: We analyze substitution tiling spaces with fivefold symmetry. In the substitution process, the introduction of randomness can be done by means of two methods which may be combined: composition of inflation rules for a given prototile set and tile rearrangements. The configurational entropy of the random substitution process is computed in the case of prototile subdivision followed by tile rearrangement. When aperiodic tilings are studied from the point of view of dynamical systems, rather than treating a single one, a collection of them is considered. Tiling spaces are defined for deterministic substitutions, which can be seen as the set of tilings that locally look like translates of a given tiling. ?ech cohomology groups are the simplest topological invariants of such spaces. The cohomologies of two deterministic pentagonal tiling spaces are studied. 1. Introduction Aperiodic tilings of the plane appeared in the literature in the works of Wang [1] and Penrose [2]. Substitution tilings with noncrystallographic planar symmetries have been intensively studied in the last decades, mainly since the discovery of quasicrystals. The structures are meaningful in several areas like the study of quasicrystalline materials and artificially fabricated macroscopic structures that can be used as photonic or phononic devices. A property of quasicrystal structures is the appearance of sharp peaks in their diffraction patterns and recent results in this direction use methods familiar from statistical mechanics and from the long-range aperiodic order of tilings [3]. A suitable approach is to work with translation invariant families of mathematical quasicrystals, instead of dealing with a single one. The action of the dynamical systems, which is usually on time, is now translation on space. For recent advances in the mathematics of diffraction in the context of dynamical systems and stochastic spatial point processes, see [4]. On the other hand, the atoms in a material modeled with a quasicrystal tiling are distributed in such a way that they determine a quasiperiodic potential. The spectrum of the associated Schr?dinger Hamiltonian has infinitely many gaps, and its distribution is related to the integer ?ech cohomology of the corresponding space of tilings [5, 6]. Other questions tied to the ?ech cohomology are connected to the derivation of the internal structure of a material from diffraction data or the type of deformations of the molecular structure that are consistent with the combinatorics of the molecular bonds [7, 8]. Pentagonal, octagonal, decagonal, and
Substitutions with Vanishing Rotationally Invariant First Cohomology
Juan García Escudero
Discrete Dynamics in Nature and Society , 2012, DOI: 10.1155/2012/818549
Abstract: The cohomology groups of tiling spaces with three-fold and nine-fold symmetries are obtained. The substitution tilings are characterized by the fact that they have vanishing first cohomology group in the space of tilings modulo a rotation. The rank of the rational first cohomology, in the tiling space formed by the closure of a translational orbit, equals the Euler totient function evaluated at if the underlying rotation group is . When the symmetries are of crystallographic type, the cohomologies are infinitely generated.
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