331 research outputs found
Quantum fractionary cosmology: K-essence theory
Using a particular form of the quantum K-essence scalar field, we show that
in the quantum formalism, a fractional differential equation in the scalar
field variable, for some epoch in the Friedmann-Robertson-Walker model
(radiation and inflation like epochs, as example), appears naturally. In the
classical analysis the kinetic energy of scalar field can falsify the standard
matter in sense that we obtain the time behavior for the scale factor in all
scenarios of our universe using the Hamiltonian formalism, where the results
are analogues to those obtained by algebraic procedure in the Einstein field
equations (see equation (6) in reference \cite{berbena}). In the case of the
quantum Wheeler DeWitt (WDW) equation for the scalar field , a fractional
differential equation of order is obtained.
This fractional equation belongs to different intervals, depending on the value
of the barotropic parameter, to say, when the order
belongs to the interval , and when the order belongs to the interval .
The corresponding quantum solutions are also given.Comment: 19 pages, 21 figure
Anisotropic fractional cosmology: K-essence theory
In the particular configuration of the scalar field K-essence in the
Wheeler-DeWitt quantum equation, for some age in the Bianchi type I anisotropic
cosmological model, a fractional differential equation for the scalar field
arises naturally. The order of the fractional differential equation is
. This fractional equation belongs to
different intervals, depending on the value of the barotropic parameter; when
, the order belongs to the interval , and when, the order belongs to the interval
. In the quantum scheme, we introduce the factor ordering
problem in the variables and its corresponding momenta
, obtaining a linear fractional differential equation
with variable coefficients in the scalar field equation and the solution is
found using a fractional series expansion. The corresponding quantum solutions
are also given. We found the classical solution in the usual gauge N obtained
in the Hamiltonian formalism and without a gauge, in the last case, the general
solution is presented in a transformed time , however in the dust era
we found a closed solution in the gauge time .Comment: 21 pages, no figure
Fenoles de interés farmacológico en hojas de vides silvestres (Vitis spp.) de México
Sedentary styles of life, along with inadequate nutritional habits, increase the risk to develop degenerative chronic diseases. Searching for possible alternatives of prevention for those risks, it has been investigated about the quality and nutraceutic properties of several agricultural commodities. The phenols are substances with important functions in vegetal organisms; and moreover they have antioxidants properties in the cellular metabolism of humans and animals. In order to quantify the content of three phenolic acids and a stilbene, it was performed analyses, by high performance liquid chromatography (HPLC-UV/Vis), on metanolic leave extracts of 97 wild grapevines (Vitis spp.) of Puebla, Mexico. Those plants were found growing in their natural environments from 207 to 2175 m. The gallic acid was the most common of the metabolites since it appeared in 96 of the 97 samples, rutin was the second most common substance and it was identified in 80 samples, the caffeic acid appeared in 29 and finally resveratrol only in 14. The leaves of wild grapevines contain diverse antioxidants substances that might have several benefits in the human health; in addition the suitable conservation, maintenance and correct advantage of this plant genus provide environmental services and the balance of ecosystems
Effect of equivalent sites on the dynamics of bimetallic nanoparticles
Using a Sutton and Chen interatomic potential, we study the molecular dynamics of Au- Pd nanoparticles with an initial icosahedral structure at different temperatures and concentrations, where each relative concentration of the 561-atom particles was made by placing atoms of the same species at equivalent sites, in order to identify under which conditions the melting transition temperature appears for each particle. In addition, we compute global order parameters in order to correlate the obtained results with the caloric curves of each particle. As a result, we observe that the melting transition temperature depends on the relative atomic positions of gold and palladium. The melting transition temperature of the Au-Pd alloy particles appears at higher temperature than that of the pure-gold particle. From the analysis of the structure of the particles, we found that the melting temperature increases with the proportion of gold atoms, and for those particles with a higher concentration of palladium on the surface, we observe an early migration of gold atoms before the melting transition temperature appears
Resveratrol content in leaves of Mexican wild grapevines (Vitis spp.)
El resveratrol es considerado una fitoalexina
pues es sintetizado como respuesta
a patógenos (factores bióticos) y en condiciones
climáticas adversas (factores abióticos).
Actualmente existe mucho interés en él por su
potencial uso en farmacología como antioxidante.
Mediante cromatografía de líquidos de
alta resolución (HPLC) se determinó el contenido
de resveratrol en hojas de 18 accesiones
de vides nativas de Puebla, México, cuatro de
ellas creciendo en cuatro condiciones ambientales
diferentes. Las concentraciones fueron
muy variables, estimándose 39,5 μg g−1 peso
fresco como valor máximo, mientras que en
algunas accesiones no fue posible detectar
resveratrol. Se observaron diferencias en el
contenido de resveratrol para accesiones
creciendo en localidades diferentes, lo que
sugiere alta influencia de los factores ambientales
sobre la expresión del genotipo en
la inducción o inhibición de la biosíntesis de
dicho metabolito secundario.Resveratrol is considered a phytoalexin,
because it is synthesized in response
to pathogens (biotic factors) and adverse climatic
conditions (abiotic factors). Nowadays
there is great interest in this substance, due
to its potential use in pharmacology as an
antioxidant. Through high performance liquid
chromatography (HPLC), resveratrol content
was determined in leaves of 18 accessions
of wild grapevines native to Puebla, Mexico;
four of them growing in four different
environmental conditions. There was high
variability in the resveratrol contents, estimating
39.5 μg g-1 fresh weight as maximum
value whereas in some accessions there
was not detection. Differences in the content
of resveratrol within the four environments
for the different accessions were observed,
suggesting high influence of the environment
on the genotype, inducting or inhibiting the
biosynthesis of that compound.Fil: Tobar-Reyes, J. Refugio.
Benemérita Universidad Autónoma de México. Escuela de Ingeniería AgrohidraúlicaFil: Franco-Mora, Omar.
Universidad Autónoma del Estado de México. Facultad de Ciencias AgrícolasFil: Morales-Rosales, Edgar Jesús.
Universidad Autónoma del Estado de México. Facultad de Ciencias AgrícolasFil: Cruz-Castillo, Juan Guillermo.
Universidad Autónoma Chapingo (México). Centro Regional Universitario Orient
Cytotoxicity of three new triazolo-pyrimidine derivatives against the plant trypanosomatid: Phytomonas sp isolated from Euphorbia characias
There is no effective chemotherapy against diseases caused by Phytomonas sp., a plant trypanosomatid responsible for economic losses in major crops. We tested three triazolo-pyrimidine complexes [two with Pt(II), and another with Ru(III)] against promastigotes of Phytomonas sp. isolated from Euphorbia characias. The incorporation of radiolabelled precursors, ultrastructural alterations and changes in the pattern of metabolite excretion were examined. Different degrees of toxicity were found for each complex: the platinun compound showed an inhibition effect on nucleic acid synthesis, provoking alterations on the levels of mitochondria, nucleus and glycosomes. These results, together with others reported previously in our laboratory about the activity of pyrimidine derivatives, reflect the potential of these compounds as agents in the treatment of Phytomonas sp.Financial support Universidad de Granada (Spain), grant BIO 2000-1429
Influence of cavity preparation technique (rotary vs. ultrasonic) on microleakage and marginal fit of six end-root filling materials
Objectives: To evaluate in vitro the effect of cavity preparation with microburs and diamond-coated ultrasonic tips on the microleakage and marginal fit of six end-root filling materials. Study Design. The following materials were assessed: amalgam (Amalcap), zinc oxide eugenol (IRM), glass ionomer (Vitrebond), compomer (Cavalite), mineral particle aggregate (MTA) and composite (Clearfil). Cavity preparation was performed with microburs or diamond ultrasonic tips in single-root teeth. The seal was evaluated in two experiments: a microleakage assay on the passage of dye to the interface; and a scanning electron microscopy study and analysis of epoxy resin replicas, measuring the size of gaps in the interface between filling material and cavity walls. Multifactorial ANOVA, multiple comparison test and Student?s t test were used for statistical analyses of the data, considering p<0.05 to be significant. Results: Clearfil and MTA achieved a hermetic seal. Leakage and interface gap size was greater with Cavalite than with Clearfil and MTA, followed by Vitrebond and IRM. The worst seal was obtained with Amalcap. The use of diamond-coated ultrasonic tips improved the seal and reduced the gap when using materials that did not hermetically seal the cavity (Amalcap, IRM, Cavalite, Vitrebond). The preparation technique did not affect materials that achieved a hermetic seal (Clearfil, MTA). Conclusions: Clearfil and MTA obtained a hermetic seal due to their excellent marginal fit and are the most recommended materials for clinical use, taking account of their sealing capacity. Ultrasonic cavity preparation is preferable because it improves the seal and marginal fit of materials that do not achieve a hermetic seal of the cavity (Amalcap, IRM, Cavalite, Vitrebond)
Comparison between Ecuadoran Genotypes of Cavy Litters (Cavia porcellus) and Cavies Bred in Peru
Background: The threat of extinction posed on different unprotected genotypes from the Andean Ranges of Ecuador is calling for new studies and preservation measures to keep the biological diversity of the area, which has enormous perspectives for human nutrition. The aim of this paper was to compare the sizes and weights up to the weaning stage of native Ecuadoran cavy litters in Azuay province, with the Peruvian-bred line.
Methods: The study took place on Irquis experimental farm, belonging to the Faculty of Agricultural Sciences, University of Cuenca, Ecuador. The database was based on the records of breeding animals screened among farmers from Azuay and Cañar, and it included their phenotypic traits.
Results: No significant differences were observed in the month of parturition, or the number of parturitions, or the genotype regarding the size of the litter at weaning. The data from Azuay and Peru were similar in terms of litter size at birth (3.1 and 3.2, respectively). However, it was higher regarding litter weight at birth and weaning (432 and 837 g, compared to the 313 and 570 g from Azuay, but no different from Cañar).
Conclusions: The native genotypes from Azuay and Cañar were inferior to the Peruvian genotype, in terms of birth weight and weaning weight. Azuay was no different from Peru, according to litter size at birth or weaning. The potential observed in this genotype should be further developed.Background: The threat of extinction posed on different unprotected genotypes from the Andean Ranges of Ecuador is calling for new studies and preservation measures to keep the biological diversity of the area, which has enormous perspectives for human nutrition. The aim of this paper was to compare the sizes and weights up to the weaning stage of native Ecuadoran cavy litters in Azuay province, with the Peruvian-bred line.
Methods: The study took place on Irquis experimental farm, belonging to the Faculty of Agricultural Sciences, University of Cuenca, Ecuador. The database was based on the records of breeding animals screened among farmers from Azuay and Cañar, and it included their phenotypic traits.
Results: No significant differences were observed in the month of parturition, or the number of parturitions, or the genotype regarding the size of the litter at weaning. The data from Azuay and Peru were similar in terms of litter size at birth (3.1 and 3.2, respectively). However, it was higher regarding litter weight at birth and weaning (432 and 837 g, compared to the 313 and 570 g from Azuay, but no different from Cañar).
Conclusions: The native genotypes from Azuay and Cañar were inferior to the Peruvian genotype, in terms of birth weight and weaning weight. Azuay was no different from Peru, according to litter size at birth or weaning. The potential observed in this genotype should be further developed
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