692 research outputs found
Cuantificación de la susceptibilidad a magulladura en frutos de hueso en términos probabilísticos.
El objetivo de este estudio es definir una magnitud que caracterice la susceptibilidad a daños mecánicos en frutos de hueso (melocotón cv. Caterina y Sudanell y albaricoque cv Búlida y Pepito). La aparición de magulladura en frutos de hueso está más relacionada con la deformación máxima alcanzada durante una carga de compresión (indicativo de su respuesta mecánica) que con el nivel de carga (fuerza) en sí mismo. La aparición de magulladura va acompañada de elevadas superficies de daño lo que hace que los frutos al magullarse queden directamente fuera del rango de aceptación comunitario (0.5cm2). Este hecho indica la necesidad de caracterizar la susceptibilidad a magulladura como probabilidad de daño. Este estudio indica la posibilidad de establecer la probabilidad de daño mediante la combinación de la respuesta mecánica del fruto (deformación máxima) y el nivel de carga (fuerza). Asimismo la respuesta mecánica se puede establecer instrumentalmente mediante la "dureza al tacto" y la tipología de comportamiento reológico
A partial study of vertical distribution of conventional no-till seeders and spatial variability of seed depth placement of maize in the Alentejo region, Portugal
The requirements for a good stand in a no-till field are the same as those for conventional planting as well as added field and machinery management. Among the
various factors that contribute towards producing a successful maize crop, seed depth placement is a key determinant. Although most no-till planters on the market work well under good soil and residue conditions, adjustments and even modifications are frequently
needed when working with compacted or wet soils or with heavy residues. The main objective of this study, carried out in 2010, 2011 and 2012, was to evaluate the vertical
distribution and spatial variability of seed depth placement in a maize crop under no-till conditions, using precision farming technologies and conventional no-till seeders. The results obtained indicate that the seed depth placement was affected by soil moisture content and forward speed. The seed depth placement was negatively correlated with soil resistance and seeding depth had a significant impact on mean emergence time and the percentage of emerged plants. Shallow average depth values and high coefficients of variation suggest a need for improvements in controlling the seeders’ sowing depth mechanism or more accurate calibration by operators in the field
The extended empirical process test for non-Gaussianity in the CMB, with an application to non-Gaussian inflationary models
In (Hansen et al. 2002) we presented a new approach for measuring
non-Gaussianity of the Cosmic Microwave Background (CMB) anisotropy pattern,
based on the multivariate empirical distribution function of the spherical
harmonics a_lm of a CMB map. The present paper builds upon the same ideas and
proposes several improvements and extensions. More precisely, we exploit the
additional information on the random phases of the a_lm to provide further
tests based on the empirical distribution function. Also we take advantage of
the effect of rotations in improving the power of our procedures. The suggested
tests are implemented on physically motivated models of non-Gaussian fields;
Monte-Carlo simulations suggest that this approach may be very promising in the
analysis of non-Gaussianity generated by non-standard models of inflation. We
address also some experimentally meaningful situations, such as the presence of
instrumental noise and a galactic cut in the map.Comment: 15 pages, 6 figures, submitted to Phys. Rev.
VME indicator species collected during exploratory fishing in Macaronesian seamounts
During the second half of 2012, the longline vessel MARANSA completed 13 fishing trips in international
waters of CECAF Area (Division FAO 34), in nine Seamounts from northeast off Madeira (Lion,
Ampere, Unicorn, Seine, “Camaguay”, “Cabezos”, Dacia and “Fantasma”) to south off the Canary Islands
(Eco/Endeavour), between latitudes 19°N and 35°N, using bottom longlines.
The main target species were demersal species such as Wreckfish (Polyprion americanus) or Splendidalfonsino
(Beryx splendens).
An observer on board recorded the bycatch of Vulnerable Marine Ecosystems (VME) indicator species
in order to evaluate the potential adverse impact of bottom fishing activities on VME and samples of the
specimens for later identification in the laboratory were stored. The main indicator species found were
cold-water corals (black corals, scleractinians and gorgonians) and sponges, species broadly associated
with seamounts.
The shallower banks, Ampere and Dacia in the north and centre of the area, show the greater biodiversity
and the higher percentage of presence of VME indicator species (52% and 53% of the sets respectively),
followed by Endeavour (South of the Canary Islands), 36.4%. In these three banks the species distribution
is strongly related to depth, finding Antipatharia (mainly Stichopathes sp) and Scleractinia (Dendrophyllia
cornigera and D. ramea) in shallower depths and Porifera (Neophryssospongia nolitangere,
Leiodermatium lynceus and Asconema setubalense) in deeper bottoms. Species of the Porifera group are
present in all banks except of so-called ”Cabezos”
Thermal leptogenesis in a model with mass varying neutrinos
In this paper we consider the possibility of neutrino mass varying during the
evolution of the Universe and study its implications on leptogenesis.
Specifically, we take the minimal seesaw model of neutrino masses and introduce
a coupling between the right-handed neutrinos and the dark energy scalar field,
the Quintessence. In our model, the right-handed neutrino masses change as the
Quintessence scalar evolves. We then examine in detail the parameter space of
this model allowed by the observed baryon number asymmetry. Our results show
that it is possible to lower the reheating temperature in this scenario in
comparison with the case that the neutrino masses are unchanged, which helps
solve the gravitino problem. Furthermore, a degenerate neutrino mass patten
with larger than the upper limit given in the minimal leptogenesis
scenario is permitted.Comment: 18 pages, 7 figures, version to appear in PR
Cosmic Microwave Background Anisotropy with Cosine-Type Quintessence
We study the Cosmic Microwave Background (CMB) anisotropies produced by
cosine-type quintessence models. In our analysis, effects of the adiabatic and
isocurvature fluctuations are both taken into account. For purely adiabatic
fluctuations with scale invariant spectrum, we obtain a stringent constraint on
the model parameters using the CMB data from COBE, BOOMERanG and MAXIMA.
Furthermore, it is shown that isocurvature fluctuations have significant
effects on the CMB angular power spectrum at low multipoles in some parameter
space, which may be detectable in future satellite experiments. Such a signal
may be used to test the cosine-type quintessence models.Comment: 21 pages, 9 figure
Equilibrium and stability of neutrino lumps as TOV solutions
We report about stability conditions for static, spherically symmetric
objects that share the essential features of mass varying neutrinos in
cosmological scenarios. Compact structures of particles with variable mass are
held together preponderantly by an attractive force mediated by a background
scalar field. Their corresponding conditions for equilibrium and stability are
given in terms of the ratio between the total mass-energy and the spherical
lump radius, . We show that the mass varying mechanism leading to lump
formation can modify the cosmological predictions for the cosmological neutrino
mass limits. Our study comprises Tolman-Oppenheimer-Volkoff solutions of
relativistic objects with non-uniform energy densities. The results leave open
some questions concerning stable regular solutions that, to an external
observer, very closely reproduce the preliminary conditions to form
Schwarzschild black holes.Comment: 20 pages, 5 figure
Observational constraint on generalized Chaplygin gas model
We investigate observational constraints on the generalized Chaplygin gas
(GCG) model as the unification of dark matter and dark energy from the latest
observational data: the Union SNe Ia data, the observational Hubble data, the
SDSS baryon acoustic peak and the five-year WMAP shift parameter. It is
obtained that the best fit values of the GCG model parameters with their
confidence level are ()
, ()
. Furthermore in this model, we can see that the
evolution of equation of state (EOS) for dark energy is similar to quiessence,
and its current best-fit value is with the confidence
level .Comment: 9 pages, 5 figure
Search for non-Gaussianity in pixel, harmonic and wavelet space: compared and combined
We present a comparison between three approaches to test non-Gaussianity of
cosmic microwave background data. The Minkowski functionals, the empirical
process method and the skewness of wavelet coefficients are applied to maps
generated from non-standard inflationary models and to Gaussian maps with point
sources included. We discuss the different power of the pixel, harmonic and
wavelet space methods on these simulated almost full-sky data (with Planck like
noise). We also suggest a new procedure consisting of a combination of
statistics in pixel, harmonic and wavelet space.Comment: Accepted for publication in PR
Combined constraints on modified Chaplygin gas model from cosmological observed data: Markov Chain Monte Carlo approach
We use the Markov Chain Monte Carlo method to investigate a global
constraints on the modified Chaplygin gas (MCG) model as the unification of
dark matter and dark energy from the latest observational data: the Union2
dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the
cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the
cosmic microwave background (CMB) data. In a flat universe, the constraint
results for MCG model are,
()
,
()
,
()
,
()
, and ()
.Comment: 12 pages, 1figur
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