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Search Results: 1 - 10 of 202286 matches for " N. Rodriguez "
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Higher-Order Corrections for the Deflection of Light around a Massive Object. Diagonal Padé Approximants and Ray-Tracing Algorithms  [PDF]
Carlos Rodriguez, Carlos Marín
International Journal of Astronomy and Astrophysics (IJAA) , 2018, DOI: 10.4236/ijaa.2018.81009
Abstract: From the Schwarzschild metric we obtain the higher-order terms for the deflection of light around a massive object using the Lindstedt-Poincaré method to solve the equation of motion of a photon around the stellar object. The asymptotic series obtained by this method was obtained up to order 20 in the expansion parameter, and was found to better approximate the numerical solution with higher order terms—a property that can’t be taken for granted for any asymptotic series. Additionally, we obtain diagonal Padé approximants from the perturbation expansion, and we show how these are a better fit for the numerical data than the original formal Taylor series. Furthermore, we use these approximants in ray-tracing algorithms to model the bending of light around massive objects.
Medios de comunicación y opacidad del conflicto de la Universidad del Cauca
Signo y Pensamiento , 2010,
Abstract: as victoria camps puts it: "[ to take] information as a reflection of reality is a myth. what it really deals with is with the disclosure or exposure of the things that happen... and, at the same time, shaping that which in fact happens". yet, the act of giving reality a "format" is not an aseptic exercise, since it implies omissions, exclusions, and silences that end up presenting half-truths, as was the case with the way two local newspapers covered universidad del cauca's conflict in 2007, fact which raises questions as to the social function of mass media in the construction of citizenship skills and the strengthening of democracy.
Belén Castellanos Rodriguez
Nómadas , 2010,
Abstract: En este escrito abordaremos los puntos centrales del tratamiento que Bataille hace sobre las particularidades de la sexualidad humana en obras como Las lágrimas de Eros y El erotismo. Se vinculará esta temática con el pensamiento general del pensador francés y con su contribución a la renovación del sentido de la filosofía.
Demographic translation and tempo effects: An accelerated failure time perspective
Germ????n Rodriguez
Demographic Research , 2006,
Abstract: In this paper I review the concept of tempo effects in demography, focusing on the tempo adjustments proposed by Bongaarts and Feeney and drawing on the work of Ryder and Zeng and Land. I show that the period-shift model that underlies the proposed adjustments can be motivated from an accelerated failure time cohort perspective. I propose alternative measures of tempo under changing fertility and mortality that share a synthetic cohort interpretation with the adjusted measure of quantum. I stress similarities between the results for fertility and mortality, particularly in terms of mean age of childbearing and mean age at death, but also note some important distinctions. I conclude that the fertility adjustments can help distinguish quantum and tempo effects, but argue that in the case of mortality the Bongaarts-Feeney measure of tempo-adjusted life expectancy differs from conventional estimates because it reflects past mortality.
Dye-Sensitized Solar Cells Based on TiO2 Nanoparticles Modified by Wet Milling  [PDF]
Anthony Huamán, Maria Quintana, Juan Rodriguez, Walter Estrada
Energy and Power Engineering (EPE) , 2014, DOI: 10.4236/epe.2014.613040
Abstract: TiO2 nanoparticles were produced from a commercial anatase powder through a wet milling process. The effect of grinding intensity, which is directly dependent on the operating parameters, was analyzed and the performance of polyethylene glycol (PEG400) as a dispersing agent in the milling system was also tested. The results showed that the processes using polyethylene glycol achieved a greater fragmentation of particles. This could be observed in the histograms made from SEM images taken from samples of powders from the processes, whose populations reached an average size of approximately 90 nm. The TiO2 powders obtained by milling were then used in the manufacture of dye-sensitized solar cells. It was verified that the powders produced using the dispersing agent achieved the greatest efficiencies, the highest being 0.94%. The current produced by the cells proved to be very low compared to the voltages obtained which gave acceptable values up to 0.81 V.
Variability in Wood Density and Wood Fibre Characterization of Woody Species and Their Possible Utility in Northeastern Mexico  [PDF]
Humberto Gonzalez Rodriguez, Ratikanta Maiti, Aruna Kumari, N. C. Sarkar
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.77109
Abstract: Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density with wood fibre characteristics. This technique can be used in the selection of species with high wood density for possible utility. Aims: It is to determine the variability in wood density and in fiber cell morphology and its length and among wood species of the Tamaulipan thornscrub, northeastern Mexico. Methods: Wood density and wood fibres are characterized in these woody species following standard methodology. Results: The results reveal large variability in wood density and in fibre cell morphology h. The species have been classified on the basis of wood density and its fibber cell morphology and has been recommended for their possible utilization for different purposes. Conclusions: Species desirable for strong furniture making, paper pulp, soft furniture, fence etc. can be selected on the basis of fibre length to breadth ratios as strong fibres for furniture and fibre cells with broad lumen and thin cell wall use for fabrication of paper pulp and other utilities.
Gas dynamics in the Milky Way: the nuclear bar and the 3-kpc arms
N. J. Rodriguez-Fernandez
Physics , 2009,
Abstract: We discuss the results of the first model of the gas dynamics in the Milky Way in the presence of two bars: the large scale primary bar or boxy bulge and a secondary bar in the Galactic center region. We have obtained an accurate potential by modeling 2MASS star counts and we have used this potential to simulate the gas dynamics. As a first approximation we have used one single pattern speed \Omega_p. The models with Omega_p=30-40 \kmskpc and a primary bar orientation of 20-35 deg reproduce successfully many characteristics of the observed longitude-velocity diagrams as the terminal velocity curve or the spiral arm tangent points. The Galactic Molecular Ring is not an actual ring but the inner part of the spiral arms, within corotation. The model reproduces quantitatively the "3-kpc arm" and the recently found far-side counterpart, which are the lateral arms that contour the bar. In the Galactic center region, the model reproduces the 1-kpc HI ring and the Central Molecular Zone (CMZ), which is the gas response to the secondary bar. In order to reproduce the observed parallelogram shape of the CO longitude velocity diagram of the CMZ, the secondary bar should be oriented by and angle of 60-70 deg with respect to the Sun-GC line. The mass of the secondary bar amounts to (2-5.5)10^9 Msun, which is 10-25 % of the mass of the primary bar.
Low Voltage Daily Energy Demand Temperature Dependent Representation by Using Circular Statistics  [PDF]
Pucheta Julián, Salas Carlos, Piumetto Miguel, Herrera Martín, Rodriguez Rivero Cristian
Applied Mathematics (AM) , 2019, DOI: 10.4236/am.2019.103006
Abstract: In this work, a tool that allows visualizing the probability of the power demand according to the temperature and the hours of the day is presented. This aim contributes to the decision making support for the transformer and its service administration. The objective is to represent the demand accurately as a color statistical map based on two variables: the time of day and the ambient temperature. Since the daily energy consumption is periodic regarding the hours of the day in terms of several days, its representation with Gaussian models becomes difficult, but it is simplified when working with circular statistics. The circular statistics used here is the Von Mises distribution, which has the parameters mean address and kappa concentration. Results obtained from measurements made over a year in a medium-voltage transformer with intervals of 60 minutes are shown.
The cardiac and haemostatic effects of dietary hempseed
Delfin Rodriguez-Leyva, Grant N Pierce
Nutrition & Metabolism , 2010, DOI: 10.1186/1743-7075-7-32
Abstract: Cannabis sativa L. is an annual plant in the Cannabaceae family. It has been an important source of food, fiber, medicine and psychoactive/religious drug since prehistoric times [1]. Cannabis is mentioned as a medication in ancient Egyptian medical texts: Ramesseum III Papyrus (1700 B.C.), Eber's Papyrus (1600 B.C.), the Berlin Papyrus (1300 B.C.), and the Chester Beatty VI Papyrus (1300 B.C.) [1,2].Two main types of Cannabis Sativa L. must be distinguished, the drug and non-drug types. The first is also known as marijuana, hashish or Cannabis tincture and contains Δ9-Tetrahydrocannabinol (THC) in concentrations between 1-20%, high enough to exhibit psychoactivity. The second type of Cannabis Sativa L. is industrial hemp with THC concentrations < 0.3% so it has no psychoactive properties [3,4].Canada, Australia, Austria, China, Great Britain, France and Spain are among the most important agricultural producers of hempseed. In the United States, it is not legal to cultivate hempseed. This is primarily because many believe that by legalizing hemp they may lead to a legalization of marijuana [5]. Other governments have accepted the distinction between the two types of Cannabis and, while continuing to penalize the growing of marijuana, have legalized the growing of industrial hemp [5].Hempseed possesses excellent nutritional value. It is very rich in essential fatty acids (EFAs) and other polyunsaturated fatty acids (PUFAs). It has almost as much protein as soybean and is also rich in Vitamin E and minerals such as phosphorus, potassium, sodium, magnesium, sulfur, calcium, iron, and zinc [6,7]. The nutrient profile of hempseed is shown in Table 1. Hempseed oil contains all of the essential amino acids and also contains surprisingly high levels of the amino acid arginine, a metabolic precursor for the production of nitric oxide (NO), a molecule now recognized as a pivotal signaling messenger in the cardiovascular system that participates in the control of hemostasis, fi
First record of Eutonina scintillans Bigelow, 1909 (Hydrozoa: Leptomedusae: Eirenidae) in temperate waters of the southwestern Atlantic Ocean
Rodriguez,Carolina; Genzano,Gabriel; Mianzán,Hermes;
Investigaciones marinas , 2007, DOI: 10.4067/S0717-71782007000200014
Abstract: we herein report the leptomedusae eutonina scintillans (bigelow, 1909) for the buenos aires coast (38°s) as a consequence of a research project dealing with hydromedusae distributions in the southwestern atlantic ocean (34°-55°s). this is the first record of this species, which was previously known for tropical waters (brazil, 16°s), in the temperate waters of the south american atlantic ocean. possible reasons for its appearance so far south are discussed
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