867 research outputs found
Possible Existence of an Extraordinary Phase in the Driven Lattice Gas
We report recent simulation results which might indicate the existence of a
new low-temperature "phase" in an Ising lattice gas, driven into a
non-equilibrium steady state by an external field. It appears that this
"phase", characterized by multiple-strip configurations, is selected when
square systems are used to approach the thermodynamic limit. We propose a
quantitative criterion for the existence of such a "phase". If confirmed, its
observation may resolve a long-standing controversy over the critical
properties of the driven Ising lattice gas.Comment: 10 pages; 4 figure
The Real-rootedness of Eulerian Polynomials via the Hermite–Biehler Theorem
Based on the Hermite–Biehler theorem, we simultaneously prove the real-rootedness of Eulerian polynomials of type and the real-rootedness of affine Eulerian polynomials of type , which were first obtained by Savage and Visontai by using the theory of -Eulerian polynomials. We also confirm Hyatt’s conjectures on the inter-lacing property of half Eulerian polynomials. Borcea and Brändén’s work on the characterization of linear operators preserving Hurwitz stability is critical to this approach
Growth, immunity and ammonia excretion of albino and normal Apostichopus japonicus (Selenka) feeding with various experimental diets
An experiment was conducted to evaluate the effects of six experimental diets on growth performance, ammonia excretion and immunity of albino and normal Apostichopus japonicus. A factorial design was used, the factors being type of diets (six levels) and colour of A. japonicus (two levels). A total of 30 randomly selected albino A. japonicus were housed in each (60 × 50 × 30 cm3) of 18 blue plastic aquaria to form six groups in triplicate, and the same set-up
was used for the normal A. japonicus. Each group of animals was fed with one of the six experimental diets. Apparent dry matter digestibility (ADMD) and apparent crude protein digestibility (ACPD) were analysed using acid-insoluble
ash (AIA) content method. At the end of the experiment, all
A. japonicus were harvested and weighed to calculate growth parameters. After weighing, six individuals from each aquarium were randomly sampled for immune indices.
Results indicated that all growth parameters of A. japonicus increased with decreasing nutrient content in their diets (p < .01), whereas an opposite result was observed in
case of the ammonia-nitrogen production by A. japonicus. Normal A. japonicus grew better (p < .01) and produced lower (p < .01) quantity of ammonia nitrogen compared to the albino A. japonicus. Immunity particularly superoxide dismutase and lysozyme activities was higher (p < .05) in normal compared to albino A. japonicus. Considering
all measured variables, D1 (diet containing crude protein, crude lipid, carbohydrate and crude ash 51.8, 8.7, 231.3, 708.2 g/kg, respectively) was the best diet among all
experimental diets. More research is still needed to optimize nutrients in the diet of A. japonicus, as this study does not provide information about critical threshold level of nutrients in diets. Until then, diet D1 can be recommended for A. japonicus aquaculture
Surface layering of liquids: The role of surface tension
Recent measurements show that the free surfaces of liquid metals and alloys
are always layered, regardless of composition and surface tension; a result
supported by three decades of simulations and theory. Recent theoretical work
claims, however, that at low enough temperatures the free surfaces of all
liquids should become layered, unless preempted by bulk freezing. Using x-ray
reflectivity and diffuse scattering measurements we show that there is no
observable surface-induced layering in water at T=298 K, thus highlighting a
fundamental difference between dielectric and metallic liquids. The
implications of this result for the question in the title are discussed.Comment: 5 pages, 4 figures, to appear in Phys. Rev. B. 69 (2004
Transforming patterned defects into dynamic poly-regional topographies in liquid crystal oligomers
We create high-aspect-ratio dynamic poly-regional surface topographies in a coating of a main-chain liquid crystal oligomer network (LCON). The topographies form at the topological defects in the director pattern organized in an array which are controlled by photopatterning of the alignment layer. The defect regions are activated by heat and/or light irradiation to form reversible topographic structures. Intrinsically, the LCON is rubbery and sensitive to temperature changes, resulting in shape transformations. We further advanced such system to make it light-responsive by incorporating azobenzene moieties. Actuation reduces the molecular order of the LCON coating that remains firmly adhered to the substrate which gives directional shear stresses around the topological defects. The stresses relax by deforming the surfaces by forming elevations or indents, depending on the type of defects. The formed topographies exhibit various features, including two types of protrusions, ridges and valleys. These poly-regional structures exhibit a large modulation amplitude of close to 60%, which is 6 times larger than the ones formed in liquid crystal networks (LCNs). After cooling or by blue light irradiation, the topographies are erased to the initial flat surface. A finite element method (FEM) model is adopted to simulate structures of surface topographies. These dynamic surface topographies with multilevel textures and large amplitude expand the application range, from haptics, controlled cell growth, to intelligent surfaces with adjustable adhesion and tribology.</p
Yukawa Couplings in Heterotic Compactification
We present a practical, algebraic method for efficiently calculating the
Yukawa couplings of a large class of heterotic compactifications on Calabi-Yau
three-folds with non-standard embeddings. Our methodology covers all of, though
is not restricted to, the recently classified positive monads over favourable
complete intersection Calabi-Yau three-folds. Since the algorithm is based on
manipulating polynomials it can be easily implemented on a computer. This makes
the automated investigation of Yukawa couplings for large classes of smooth
heterotic compactifications a viable possibility.Comment: 38 page
Patterns in Calabi-Yau Distributions
We explore the distribution of topological numbers in Calabi–Yau manifolds, using the Kreuzer–Skarke dataset of hypersurfaces in toric varieties as a testing ground. While the Hodge numbers are well-known to exhibit mirror symmetry, patterns in frequencies of combination thereof exhibit striking new patterns. We find pseudo-Voigt and Planckian distributions with high confidence and exact fit for many substructures. The patterns indicate typicality within the landscape of Calabi–Yau manifolds of various dimension
The vertex in a Sum Rule approach
The study of charmonium dissociation in heavy ion collisions is generally
performed in the framework of effective Lagrangians with meson exchange. Some
studies are also developed with the intention of calculate form factors and
coupling constants related with charmed and light mesons. These quantities are
important in the evaluation of charmonium cross sections. In this paper we
present a calculation of the vertex that is a possible interaction
vertex in some meson-exchange models spread in the literature. We used the
standard method of QCD Sum Rules in order to obtain the vertex form factor as a
function of the transferred momentum. Our results are compatible with the value
of this vertex form factor (at zero momentum transfer) obtained in the
vector-meson dominance model.Comment: Accepted for publication in Physics Letters
Heterotic Compactification, An Algorithmic Approach
We approach string phenomenology from the perspective of computational
algebraic geometry, by providing new and efficient techniques for proving
stability and calculating particle spectra in heterotic compactifications. This
is done in the context of complete intersection Calabi-Yau manifolds in a
single projective space where we classify positive monad bundles. Using a
combination of analytic methods and computer algebra we prove stability for all
such bundles and compute the complete particle spectrum, including gauge
singlets. In particular, we find that the number of anti-generations vanishes
for all our bundles and that the spectrum is manifestly moduli-dependent.Comment: 36 pages, Late
Distribution of Energy-Momentum in a Schwarzschild-Quintessence Space-time Geometry
An analysis of the energy-momentum localization for a four-dimensional\break
Schwarzschild black hole surrounded by quintessence is presented in order to
provide expressions for the distributions of energy and momentum. The
calculations are performed by using the Landau-Lifshitz and Weinberg
energy-momentum complexes. It is shown that all the momenta vanish, while the
expression for the energy depends on the mass of the black hole, the state
parameter and the normalization factor . The special case of
is also studied, and two limiting cases are examined.Comment: 9 page
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