Critical resonance in the non-intersecting lattice path model

We study the phase transition in the honeycomb dimer model (equivalently, monotone non-intersecting lattice path model). At the critical point the system has a strong long-range dependence; in particular, periodic boundary conditions give rise to a ``resonance'' phenomenon, where the partition function and other properties of the system depend sensitively on the shape of the domain.Comment: 28 pages, 6 figures. v4 has changes suggested by refere

Effects of Different Pelleted Diets and Pellet Size on Bird Performance

An experiment investigated performance of birds fed the pelleted corn-soy diet versus the pelleted 30% copra meal based diet with different pellet sizes. This study was conducted for six weeks. A total of 144 male day old chicks were used in this trial. One day old birds were randomly allocated to four treatment diets with six replications. The starter and grower pelleted diets were with or without 30% copra meal and in two forms, either fine or mixed sized particles. The experimental design was a two way factorial with two basal diets, two particle sizes and six replicate cages of six birds per treatment. The inclusion of 30% copra meal in the pelleted diet decreased body weight and feed intake, but improved feed eficiency. Grinding the diet to a fine pellet size impaired the body weight and feed intake. The effect of pellet size became more evident when the birds grew older. Birds fed the pelleted form of copra meal accelerated their growth rate so that they were not significantly different from the weight of birds fed the pelleted form of the corn-soy diet. However the feed intake of birds fed the pelleted copra meal diet was lower than the feed intake of those fed the pelleted corn soy diets. It was concluded that inclusion of copra meal in the diet impaired growth of birds, particularly in the starter phase. Pelleting and crumbling copra meal diet could increase the bird performance to the same level of the performance of birds fed the pelleted corn-soy control diet while fine grinding the pelleted diet reversed this trend. (Animal Production 11(3): 165-169 (2009) Key Words: broilers, pellet diet, pellet size, copra mea

Effects of Different Pelleted Diets and Pellet Size on Bird Performance

An experiment investigated performance of birds fed the pelleted corn-soy diet versus the pelleted 30% copra meal based diet with different pellet sizes. This study was conducted for six weeks. A total of 144 male day old chicks were used in this trial. One day old birds were randomly allocated to four treatment diets with six replications. The starter and grower pelleted diets were with or without 30% copra meal and in two forms, either fine or mixed sized particles. The experimental design was a two way factorial with two basal diets, two particle sizes and six replicate cages of six birds per treatment. The inclusion of 30% copra meal in the pelleted diet decreased body weight and feed intake, but improved feed eficiency. Grinding the diet to a fine pellet size impaired the body weight and feed intake. The effect of pellet size became more evident when the birds grew older. Birds fed the pelleted form of copra meal accelerated their growth rate so that they were not significantly different from the weight of birds fed the pelleted form of the corn-soy diet. However the feed intake of birds fed the pelleted copra meal diet was lower than the feed intake of those fed the pelleted corn soy diets. It was concluded that inclusion of copra meal in the diet impaired growth of birds, particularly in the starter phase. Pelleting and crumbling copra meal diet could increase the bird performance to the same level of the performance of birds fed the pelleted corn-soy control diet while fine grinding the pelleted diet reversed this trend. (Animal Production 11(3): 165-169 (2009

One Dimensional Magnetized TG Gas Properties in an External Magnetic Field

With Girardeau's Fermi-Bose mapping, we have constructed the eigenstates of a TG gas in an external magnetic field. When the number of bosons $N$ is commensurate with the number of potential cycles $M$, the probability of this TG gas in the ground state is bigger than the TG gas raised by Girardeau in 1960. Through the comparison of properties between this TG gas and Fermi gas, we find that the following issues are always of the same: their average value of particle's coordinate and potential energy, system's total momentum, single-particle density and the pair distribution function. But the reduced single-particle matrices and their momentum distributions between them are different.Comment: 6 pages, 4 figure

Coagulation by Random Velocity Fields as a Kramers Problem

We analyse the motion of a system of particles suspended in a fluid which has a random velocity field. There are coagulating and non-coagulating phases. We show that the phase transition is related to a Kramers problem, and use this to determine the phase diagram, as a function of the dimensionless inertia of the particles, epsilon, and a measure of the relative intensities of potential and solenoidal components of the velocity field, Gamma. We find that the phase line is described by a function which is non-analytic at epsilon=0, and which is related to escape over a barrier in the Kramers problem. We discuss the physical realisations of this phase transition.Comment: 4 pages, 3 figure

Dynamical diffraction in sinusoidal potentials: uniform approximations for Mathieu functions

Eigenvalues and eigenfunctions of Mathieu's equation are found in the short wavelength limit using a uniform approximation (method of comparison with a `known' equation having the same classical turning point structure) applied in Fourier space. The uniform approximation used here relies upon the fact that by passing into Fourier space the Mathieu equation can be mapped onto the simpler problem of a double well potential. The resulting eigenfunctions (Bloch waves), which are uniformly valid for all angles, are then used to describe the semiclassical scattering of waves by potentials varying sinusoidally in one direction. In such situations, for instance in the diffraction of atoms by gratings made of light, it is common to make the Raman-Nath approximation which ignores the motion of the atoms inside the grating. When using the eigenfunctions no such approximation is made so that the dynamical diffraction regime (long interaction time) can be explored.Comment: 36 pages, 16 figures. This updated version includes important references to existing work on uniform approximations, such as Olver's method applied to the modified Mathieu equation. It is emphasised that the paper presented here pertains to Fourier space uniform approximation

Inhibition of Tendon Cell Proliferation and Matrix Glycosaminoglycan Synthesis by Non-Steroidal Anti-Inflammatory Drugs in vitro

The purpose of this study was to investigate the effects of some commonly used non-steroidal anti-inflammatory drugs (NSAIDs) on human tendon. Explants of human digital flexor and patella tendons were cultured in medium containing pharmacological concentrations of NSAIDs. Cell proliferation was measured by incorporation of 3H-thymidine and glycosaminoglycan synthesis was measured by incorporation of 35S-Sulphate. Diclofenac and aceclofenac had no significant effect either on tendon cell proliferation or glycosaminoglycan synthesis. Indomethacin and naproxen inhibited cell proliferation in patella tendons and inhibited glycosaminoglycan synthesis in both digital flexor and patella tendons. If applicable to the in vivo situation, these NSAIDs should be used with caution in the treatment of pain after tendon injury and surgery

On the Aggregation of Inertial Particles in Random Flows

We describe a criterion for particles suspended in a randomly moving fluid to aggregate. Aggregation occurs when the expectation value of a random variable is negative. This random variable evolves under a stochastic differential equation. We analyse this equation in detail in the limit where the correlation time of the velocity field of the fluid is very short, such that the stochastic differential equation is a Langevin equation.Comment: 16 pages, 2 figure

Unmixing in Random Flows

We consider particles suspended in a randomly stirred or turbulent fluid. When effects of the inertia of the particles are significant, an initially uniform scatter of particles can cluster together. We analyse this 'unmixing' effect by calculating the Lyapunov exponents for dense particles suspended in such a random three-dimensional flow, concentrating on the limit where the viscous damping rate is small compared to the inverse correlation time of the random flow (that is, the regime of large Stokes number). In this limit Lyapunov exponents are obtained as a power series in a parameter which is a dimensionless measure of the inertia. We report results for the first seven orders. The perturbation series is divergent, but we obtain accurate results from a Pade-Borel summation. We deduce that particles can cluster onto a fractal set and show that its dimension is in satisfactory agreement with previously reported in simulations of turbulent Navier-Stokes flows. We also investigate the rate of formation of caustics in the particle flow.Comment: 39 pages, 8 figure

Oscillatory Tunnel Splittings in Spin Systems: A Discrete Wentzel-Kramers-Brillouin Approach

Certain spin Hamiltonians that give rise to tunnel splittings that are viewed in terms of interfering instanton trajectories, are restudied using a discrete WKB method, that is more elementary, and also yields wavefunctions and preexponential factors for the splittings. A novel turning point inside the classically forbidden region is analysed, and a general formula is obtained for the splittings. The result is appled to the \Fe8 system. A previous result for the oscillation of the ground state splitting with external magnetic field is extended to higher levels.Comment: RevTex, one ps figur