6,035 research outputs found
Discovering an active subspace in a single-diode solar cell model
Predictions from science and engineering models depend on the values of the
model's input parameters. As the number of parameters increases, algorithmic
parameter studies like optimization or uncertainty quantification require many
more model evaluations. One way to combat this curse of dimensionality is to
seek an alternative parameterization with fewer variables that produces
comparable predictions. The active subspace is a low-dimensional linear
subspace defined by important directions in the model's input space; input
perturbations along these directions change the model's prediction more, on
average, than perturbations orthogonal to the important directions. We describe
a method for checking if a model admits an exploitable active subspace, and we
apply this method to a single-diode solar cell model with five input
parameters. We find that the maximum power of the solar cell has a dominant
one-dimensional active subspace, which enables us to perform thorough parameter
studies in one dimension instead of five
Giornata di studio su orticoltura biologica e risorse genetiche
The Conference-type event describes a workshop regarding the organic horticulture and the involved genetic resources. In this workshop a relevant presence of organic farmers was obtained. In this workshop, preliminary results of FAVORDENONDE Project were presented (see attached programme)
Giornata di studio su orticoltura biologica e risorse genetiche
The Conference-type event describes a workshop regarding the organic horticulture and the involved genetic resources. In this workshop a relevant presence of organic farmers was obtained. In this workshop, preliminary results of FAVORDENONDE Project were presented (see attached programme)
A Complete Statistical Analysis for the Quadrupole Amplitude in an Ellipsoidal Universe
A model of Universe with a small eccentricity due to the presence of a
magnetic field at the decoupling time (i.e. an Ellipsoidal Universe) has been
recently proposed for the solution of the low quadrupole anomaly of the angular
power spectrum of cosmic microwave background anisotropies. We present a
complete statistical analysis of that model showing that the probability of
increasing of the amplitude of the quadrupole is larger than the probability of
decreasing in the whole parameters' space.Comment: 5 pages, 3 figure
Effect of tomato variety, cultivation, climate and processing on Sola l 4, an allergen from Solanum lycopersicum
Tomatoes (Solanum lycopersicum) are one of the most consumed vegetables worldwide.
However, tomato allergies in patients suffering from birch pollen allergy occur frequently.
Due to highly similar protein structures of the tomato allergen Sola l 4 and the major birch
pollen allergen Bet v 1, patients cross-react with allergenic proteins from tomato as well as
other fruits or vegetables. The aim of this study was to quantify Sola l 4 in various tomatoes
differing in color, size and shape for identification of varieties with a reduced allergen level.
Therefore, an indirect competitive ELISA using a specific polyclonal Sola l 4 antibody was
developed. In addition, two varieties, both cultivated either conventionally or organically and
furthermore dried with different methods, were analyzed to investigate the influence of the
cultivation method and processing techniques on Sola l 4 level. Within 23 varieties, Sola l 4
content varied significantly between 0.24 and 1.71 μg Sola l 4/g FW. The tomato cultivars
Rugantino and Rhianna showed the significantly lowest level, whereas in cultivars Farbini
and Bambello the significantly highest concentration was determined. Drying of tomatoes in
the oven and by sun resulted in a significant decrease. The thermal instability was verified
for the recombinant Sola l 4 emphasizing the results for the native protein in dried tomato
samples. Overall, the Sola l 4 content is cultivar-dependent and no correlation between
color and Sola l 4 amount was found. During the drying process of tomatoes Sola l 4 level
was significantly reduced due to thermal instability. Growing conditions have a minor effect
whereas seasonal effects show a more pronounced impact. These findings could extend
the knowledge about the allergen level of different tomato varieties and may help to improve
food safety to potentially increase the life quality of patients suffering from birch pollen
allergy
The Lazarus project: A pragmatic approach to binary black hole evolutions
We present a detailed description of techniques developed to combine 3D
numerical simulations and, subsequently, a single black hole close-limit
approximation. This method has made it possible to compute the first complete
waveforms covering the post-orbital dynamics of a binary black hole system with
the numerical simulation covering the essential non-linear interaction before
the close limit becomes applicable for the late time dynamics. To determine
when close-limit perturbation theory is applicable we apply a combination of
invariant a priori estimates and a posteriori consistency checks of the
robustness of our results against exchange of linear and non-linear treatments
near the interface. Once the numerically modeled binary system reaches a regime
that can be treated as perturbations of the Kerr spacetime, we must
approximately relate the numerical coordinates to the perturbative background
coordinates. We also perform a rotation of a numerically defined tetrad to
asymptotically reproduce the tetrad required in the perturbative treatment. We
can then produce numerical Cauchy data for the close-limit evolution in the
form of the Weyl scalar and its time derivative
with both objects being first order coordinate and tetrad invariant. The
Teukolsky equation in Boyer-Lindquist coordinates is adopted to further
continue the evolution. To illustrate the application of these techniques we
evolve a single Kerr hole and compute the spurious radiation as a measure of
the error of the whole procedure. We also briefly discuss the extension of the
project to make use of improved full numerical evolutions and outline the
approach to a full understanding of astrophysical black hole binary systems
which we can now pursue.Comment: New typos found in the version appeared in PRD. (Mostly found and
collected by Bernard Kelly
Dynamics of Ferromagnetic Walls: Gravitational Properties
We discuss a new mechanism which allows domain walls produced during the
primordial electroweak phase transition. We show that the effective surface
tension of these domain walls can be made vanishingly small due to a peculiar
magnetic condensation induced by fermion zero modes localized on the wall. We
find that in the perfect gas approximation the domain wall network behaves like
a radiation gas. We consider the recent high-red shift supernova data and we
find that the corresponding Hubble diagram is compatible with the presence in
the Universe of a ideal gas of ferromagnetic domain walls. We show that our
domain wall gas induces a completely negligible contribution to the large-scale
anisotropy of the microwave background radiation.Comment: Replaced with revised version, accepted for publication in IJMP
Testing the Isotropy of the Universe with Type Ia Supernovae
We analyze the magnitude-redshift data of type Ia supernovae included in the
Union and Union2 compilations in the framework of an anisotropic Bianchi type I
cosmological model and in the presence of a dark energy fluid with anisotropic
equation of state. We find that the amount of deviation from isotropy of the
equation of state of dark energy, the skewness \delta, and the present level of
anisotropy of the large-scale geometry of the Universe, the actual shear
\Sigma_0, are constrained in the ranges -0.16 < \delta < 0.12 and -0.012 <
\Sigma_0 < 0.012 (1\sigma C.L.) by Union2 data. Supernova data are then
compatible with a standard isotropic universe (\delta = \Sigma_0 = 0), but a
large level of anisotropy, both in the geometry of the Universe and in the
equation of state of dark energy, is allowed.Comment: 12 pages, 7 figures, 2 tables. Union2 analysis added. New references
added. To appear in Phys. Rev.
Large Merger Recoils and Spin Flips From Generic Black-Hole Binaries
We report the first results from evolutions of a generic black-hole binary,
i.e. a binary containing unequal mass black holes with misaligned spins. Our
configuration, which has a mass ratio of 2:1, consists of an initially
non-spinning hole orbiting a larger, rapidly spinning hole (specific spin a/m =
0.885), with the spin direction oriented -45 degrees with respect to the
orbital plane. We track the inspiral and merger for ~2 orbits and find that the
remnant receives a substantial kick of 454 km/s, more than twice as large as
the maximum kick from non-spinning binaries. The remnant spin direction is
flipped by 103 degrees with respect to the initial spin direction of the larger
hole. We performed a second run with anti-aligned spins, a/m = +-0.5 lying in
the orbital plane that produces a kick of 1830 km/s off the orbital plane. This
value scales to nearly 4000 km/s for maximally spinning holes. Such a large
recoil velocity opens the possibility that a merged binary can be ejected even
from the nucleus of a massive host galaxy.Comment: 4 pages. Accepted for publication in ApJ
Collision of spinning black holes in the close limit
In this paper we consider the collision of spinning holes using first order
perturbation theory of black holes (Teukolsky formalism). With these results
(along with ones, we published in the past) one can predict the properties of
the gravitational waves radiated from the late stage inspiral of two spinning,
equal mass black holes. Also we note that the energy radiated by the head-on
collision of two spinning holes with spins (that are equal and opposite)
aligned along the common axis is more than the case in which the spins are
perpendicular to the axis of the collision.Comment: 6 pages, 3 figures, submitted to PR
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