524 research outputs found
Red yeast (Phaffia rhodozyma) and its effect on growth, antioxidant activity and color pigmentation of rainbow trout (Oncorhynchus mykiss)
Efficacy of orally used of red yeast (Phaffia rhodozyma) (1.6 mg astaxanthin/g product) at 15.5 g (P1), 37.3 g (P2) and 47 (P3) g per kg diet were studied on performance, carcass composition, antioxidant activity and fillet pigmentation in rainbow trout (Oncorhynchus mykiss) weighing 208–212 g for eight weeks at 11 °C. Synthetic astaxanthin (AX) (0.5 g/kg diet) and basal diet were used as controls. With an increase in P. rhodozyma concentration in diet, weight gain and specific growth rate exhibited an increase compared to basal diet (P 0.05). Water holding capacity and lipid loss in fillets of treatments were lower than fish fed basal diet (P < 0.05). By increasing P. rhodozyma concentration in fish diets, redness value exhibited a progressive increase, and the highest value was seen in P3 diet compared to other treatments (P < 0.05). These data show application of P. rhodozyma at 47 g/kg diet in trout could provide a better performance, antioxidant activities, and fillet pigmentation
Electron correlation energy in confined two-electron systems
Radial, angular and total correlation energies are calculated for four
two-electron systems with atomic numbers Z=0-3 confined within an impenetrable
sphere of radius R. We report accurate results for the non-relativistic,
restricted Hartree-Fock and radial limit energies over a range of confinement
radii from 0.05 - 10 a0. At small R, the correlation energies approach limiting
values that are independent of Z while at intermediate R, systems with Z > 1
exhibit a characteristic maximum in the correlation energy resulting from an
increase in the angular correlation energy which is offset by a decrease in the
radial correlation energy
A mathematical framework for contact detection between quadric and superquadric surfaces
The calculation of the minimum distance between surfaces plays an important role in computational mechanics, namely, in the study of constrained multibody systems where contact forces take part. In this paper, a general rigid contact detection methodology for non-conformal bodies, described by ellipsoidal and superellipsoidal surfaces, is presented. The mathematical framework relies on simple algebraic and differential geometry, vector calculus, and on the C2 continuous implicit representations of the surfaces. The proposed methodology establishes a set of collinear and orthogonal constraints between vectors defining the contacting surfaces that, allied with loci constraints, which are specific to the type of surface being used, formulate the contact problem. This set of non-linear equations is solved numerically with the Newton-Raphson method with Jacobian matrices calculated analytically. The method outputs the coordinates of the pair of points with common normal vector directions and, consequently, the minimum distance between both surfaces. Contrary to other contact detection methodologies, the proposed mathematical framework does not rely on polygonal-based geometries neither on complex non-linear optimization formulations. Furthermore, the methodology is extendable to other surfaces that are (strictly) convex, interact in a non-conformal fashion, present an implicit representation, and that are at least C2 continuous. Two distinct methods for calculating the tangent and binormal vectors to the implicit surfaces are introduced: (i) a method based on the Householder reflection matrix; and (ii) a method based on a square plate rotation mechanism. The first provides a base of three orthogonal vectors, in which one of them is collinear to the surface normal. For the latter, it is shown that, by means of an analogy to the referred mechanism, at least two non-collinear vectors to the normal vector can be determined. Complementarily, several mathematical and computational aspects, regarding the rigid contact detection methodology, are described. The proposed methodology is applied to several case tests involving the contact between different (super)ellipsoidal contact pairs. Numerical results show that the implemented methodology is highly efficient and accurate for ellipsoids and superellipsoids.Fundação para a Ciência e a Tecnologia (FCT
Negative Parity 70-plet Baryon Masses in the 1/Nc Expansion
The masses of the negative parity SU(6) 70-plet baryons are analyzed in the
1/Nc expansion to order 1/Nc and to first order in SU(3) breaking. At this
level of precision there are twenty predictions. Among them there are the well
known Gell-Mann Okubo and equal spacing relations, and four new relations
involving SU(3) breaking splittings in different SU(3) multiplets. Although the
breaking of SU(6) symmetry occurs at zeroth order in 1/Nc, it turns out to be
small. The dominant source of the breaking is the hyperfine interaction which
is of order 1/Nc. The spin-orbit interaction, of zeroth order in 1/Nc, is
entirely fixed by the splitting between the singlet states Lambda(1405) and
Lambda(1520), and the spin-orbit puzzle is solved by the presence of other
zeroth order operators involving flavor exchange.Comment: 31 pages, 3 figure
An inflation model with large variations in spectral index
Recent fits of cosmological parameters by the Wilkinson Microwave Anisotropy
Probe (WMAP) measurement favor a primordial scalar spectrum with varying index.
This result, if stands, could severely constrain inflation model buildings.
Most extant slow-roll inflation models allow for only a tiny amount of scale
variations in the spectrum. We propose in this paper an extra-dimensional
inflation model which is natural theoretically and can generate the required
variations of the spectral index as implied by the WMAP for suitable choices of
parameters.Comment: 5 pages, 3 figures, REVTeX 4. Comments on low CMB quadrupoles added;
Version accepted for publication in Phys. Rev.
Inflation, cold dark matter, and the central density problem
A problem with high central densities in dark halos has arisen in the context
of LCDM cosmologies with scale-invariant initial power spectra. Although n=1 is
often justified by appealing to the inflation scenario, inflationary models
with mild deviations from scale-invariance are not uncommon and models with
significant running of the spectral index are plausible. Even mild deviations
from scale-invariance can be important because halo collapse times and
densities depend on the relative amount of small-scale power. We choose several
popular models of inflation and work out the ramifications for galaxy central
densities. For each model, we calculate its COBE-normalized power spectrum and
deduce the implied halo densities using a semi-analytic method calibrated
against N-body simulations. We compare our predictions to a sample of dark
matter-dominated galaxies using a non-parametric measure of the density. While
standard n=1, LCDM halos are overdense by a factor of 6, several of our example
inflation+CDM models predict halo densities well within the range preferred by
observations. We also show how the presence of massive (0.5 eV) neutrinos may
help to alleviate the central density problem even with n=1. We conclude that
galaxy central densities may not be as problematic for the CDM paradigm as is
sometimes assumed: rather than telling us something about the nature of the
dark matter, galaxy rotation curves may be telling us something about inflation
and/or neutrinos. An important test of this idea will be an eventual consensus
on the value of sigma_8, the rms overdensity on the scale 8 h^-1 Mpc. Our
successful models have values of sigma_8 approximately 0.75, which is within
the range of recent determinations. Finally, models with n>1 (or sigma_8 > 1)
are highly disfavored.Comment: 13 pages, 6 figures. Minor changes made to reflect referee's
Comments, error in Eq. (18) corrected, references updated and corrected,
conclusions unchanged. Version accepted for publication in Phys. Rev. D,
scheduled for 15 August 200
Teste imunoenzimático com base em anticorpo monoclonal para a detecção de anticorpos contra os herpesvírus bovino tipos 1 e 5
Prevalência de anticorpos contra o vírus da mamilite herpética em bovinos do Rio Grande do Sul, Brasil
Level of satisfaction of online classes by students of Physical Education of Chile in times of pandemic
Indexación ScopusEn Chile el primer caso de COVID-19 fue diagnosticado el tres de marzo del 2020 y el día dieciocho del mismo mes
el presidente decreto estado de catástrofe, por lo que las clases a nivel escolar y universitario pasaron de la presencialidad a la virtualidad. El
presente estudio tiene como objetivo conocer el nivel de satisfacción de las clases virtuales de los estudiantes de Educación Física. Metodología:
Cuantitativa, no experimental, transversal. La muestra estuvo constituida por 542 alumnos de Educación Física de diferentes casas de estudio
de Chile. Se adaptó y validó la escala Satisfacción clases online. Resultados: existen diferencias significativas comparando las asignaturas teóricas
y prácticas, siendo mejor valoradas las cátedras teóricas. También se encontraron diferencias por sexo, donde los varones poseen una percepción
más negativa sobre las clases virtuales y al comparar por curso, los alumnos de primer año poseen una percepción más positiva sobre las clases
virtuales en relación con los cursos superiores. Conclusiones: existe una resistencia por parte de los alumnos a las clases virtuales en la
Educación Física, pues, si bien se encontraron diferencias significativas entre las asignaturas teóricas y prácticas, los valores siempre estuvieron
alrededor de 3 en una escala de 1 a 5. Se hacen necesarias futuras investigaciones con otras variables como actividad física, niveles de estrés y
estrategias para la enseñanza de la Educación Física virtual.In Chile the first case of COVID-19 was diagnosed on March 3, 2020 and on the eighteenth of the same month the
president decreed state of catastrophe, so that classes at school and university level went from the presence to the virtuality. The present study
aims to know the level of satisfaction of the virtual classes of the students of Physical Education. Methodology: Quantitative, non experimental,
transversal. The sample consisted of 542 students of Physical Education from different study houses in Chile. The Satisfaction scale online
classes was adapted and validated. Results: there are significant differences comparing theoretical and practical subjects, with theoretical chairs
being better valued. Differences were also found by sex, where males have a more negative perception about virtual classes and when
comparing by course, freshmen have a more positive perception about virtual classes in relation to higher courses. Conclusions: there is a
resistance on the part of students to virtual classes in Physical Education, because, although significant differences were found between the
theoretical and practical subjects, values were always around 3 on a scale of 1 to 5. Future research with other variables such as physical activity,
stress levels and strategies for the teaching of Virtual Physical Education are necessary.https://recyt-fecyt-es.recursosbiblioteca.unab.cl/index.php/retos/article/view/8290
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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