8,054 research outputs found
Leucena: procedimentos e cuidados para um bom estabelecimento.
bitstream/item/142941/1/1761.pd
Hybrid phase at the quantum melting of the Wigner crystal
We study the quantum melting of the two-dimensional Wigner crystal using a
fixed node quantum Monte-Carlo approach. In addition to the two already known
phases (Fermi liquid at large density and Wigner crystal at low density), we
find a third stable phase at intermediate values of the density. The third
phase has hybrid behaviors in between a liquid and a solid. This hybrid phase
has the nodal structure of a Slater determinant constructed out of the bands of
a triangular lattice.Comment: 5 pages, 4 figure
Implementation of barycentric resampling for continuous wave searches in gravitational wave data
We describe an efficient implementation of a coherent statistic for
continuous gravitational wave searches from neutron stars. The algorithm works
by transforming the data taken by a gravitational wave detector from a moving
Earth bound frame to one that sits at the Solar System barycenter. Many
practical difficulties arise in the implementation of this algorithm, some of
which have not been discussed previously. These difficulties include
constraints of small computer memory, discreteness of the data, losses due to
interpolation and gaps in real data. This implementation is considerably more
efficient than previous implementations of these kinds of searches on Laser
Interferometer Gravitational Wave (LIGO) detector data.Comment: 10 pages, 3 figure
High-contrast imaging of 180{\deg} ferroelectric domains by optical microscopy using ferroelectric liquid crystals
Ferroelectric liquid crystals (FLCs) couple the direction of their
spontaneous electric polarization to the direction of tilt of their optic axis.
Consequently, reversal of the electric polarization by an electric field gives
rise to an immediate and lasting optical response when an appropriately aligned
FLC is observed between crossed polarizers, with one field direction yielding a
dark image, and the opposite direction yielding a bright image. Here this
peculiar electro-optic response is used to image, with high optical contrast,
180{\deg} ferroelectric domains in a crystalline substrate of magnesium-doped
lithium niobate. The lithium niobate substrate contains a few domains with
upwards electric polarization surrounded by regions with downward electric
polarization. In contrast to a reference non-chiral liquid crystal that is
unable to show ferroelectric behavior due to its high symmetry, the FLC, which
is used as a thin film confined between the lithium niobate substrate and an
inert aligning substrate, reveals ferroelectric domains as well as their
boundaries, with strong black and white contrast. The results show that FLCs
can be used for non-destructive read-out of domains in underlying
ferroelectrics, with potential applications in e.g. photonic devices and
non-volatile ferroelectric memories.Comment: 12 pages, 3 figure
Consumer Perception of Bread Quality
Bread contains a wide range of important nutritional components which provide a positive effect on human health. However, the consumption of bread in Belgium is declining during the last decades. This is due to factors such as changing eating patterns and a increasing choice of substitutes like breakfast cereals and fast foods. The aim of this study is to investigate consumer’s quality perception of bread towards sensory, health and nutrition attributes. Consumer’s quality perception of bread seams to be determined by sensory and health attributes. Three clusters of consumers are identified based on these attributes. In the first cluster, consumers’ quality perception of bread is not dependent on the health attributes it embraces, but to some extent on sensory attributes. For the second cluster, both health and sensory attributes appear to influence quality perception. In the third cluster only sensory attributes appear to be important in determining quality perception, though in a negative direction. The results of this study will possibly help health professionals and policy makers to systematically inform the consumers about the positive effects of bread and its components. Furthermore, firms can use the result to build up a tailor-made marketing strategy.Consumer, Quality perception, Bread, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,
Arborização melhora a fertilidade do solo em pastagens cultivadas.
bitstream/item/65329/1/COT-29-Arborizacao-melhora-a-fertilidade.pd
Macroscopic behavior of bidisperse suspensions of noncolloidal particles in yield stress fluids
We study both experimentally and theoretically the rheological behavior of
isotropic bidisperse suspensions of noncolloidal particles in yield stress
fluids. We focus on materials in which noncolloidal particles interact with the
suspending fluid only through hydrodynamical interactions. We observe that both
the elastic modulus and yield stress of bidisperse suspensions are lower than
those of monodisperse suspensions of same solid volume fraction. Moreover, we
show that the dimensionless yield stress of such suspensions is linked to their
dimensionless elastic modulus and to their solid volume fraction through the
simple equation of Chateau et al.[J. rheol. 52, 489-506 (2008)]. We also show
that the effect of the particle size heterogeneity can be described by means of
a packing model developed to estimate random loose packing of assemblies of dry
particles. All these observations finally allow us to propose simple closed
form estimates for both the elastic modulus and the yield stress of bidisperse
suspensions: while the elastic modulus is a function of the reduced volume
fraction only, where is the estimated random loose
packing, the yield stress is a function of both the volume fraction and
the reduced volume fraction
CaracterÃsticas e potencialidades de pastagens de braquiárias para produção de leite.
bitstream/item/81945/1/Caracteristicas-e-potencialidades.pd
A review of Quantum Gravity at the Large Hadron Collider
The aim of this article is to review the recent developments in the
phenomenology of quantum gravity at the Large Hadron Collider. We shall pay
special attention to four-dimensional models which are able to lower the
reduced Planck mass to the TeV region and compare them to models with a large
extra-dimensional volume. We then turn our attention to reviewing the emission
of gravitons (massless or massive) at the LHC and to the production of small
quantum black holes.Comment: 32 pages, invited revie
Curved Flats, Pluriharmonic Maps and Constant Curvature Immersions into Pseudo-Riemannian Space Forms
We study two aspects of the loop group formulation for isometric immersions
with flat normal bundle of space forms. The first aspect is to examine the loop
group maps along different ranges of the loop parameter. This leads to various
equivalences between global isometric immersion problems among different space
forms and pseudo-Riemannian space forms. As a corollary, we obtain a
non-immersibility theorem for spheres into certain pseudo-Riemannian spheres
and hyperbolic spaces.
The second aspect pursued is to clarify the relationship between the loop
group formulation of isometric immersions of space forms and that of
pluriharmonic maps into symmetric spaces. We show that the objects in the first
class are, in the real analytic case, extended pluriharmonic maps into certain
symmetric spaces which satisfy an extra reality condition along a totally real
submanifold. We show how to construct such pluriharmonic maps for general
symmetric spaces from curved flats, using a generalised DPW method.Comment: 21 Pages, reference adde
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