The dynamics of thin vibrated granular layers

We describe a series of experiments and computer simulations on vibrated granular media in a geometry chosen to eliminate gravitationally induced settling. The system consists of a collection of identical spherical particles on a horizontal plate vibrating vertically, with or without a confining lid. Previously reported results are reviewed, including the observation of homogeneous, disordered liquid-like states, an instability to a `collapse' of motionless spheres on a perfect hexagonal lattice, and a fluctuating, hexagonally ordered state. In the presence of a confining lid we see a variety of solid phases at high densities and relatively high vibration amplitudes, several of which are reported for the first time in this article. The phase behavior of the system is closely related to that observed in confined hard-sphere colloidal suspensions in equilibrium, but with modifications due to the effects of the forcing and dissipation. We also review measurements of velocity distributions, which range from Maxwellian to strongly non-Maxwellian depending on the experimental parameter values. We describe measurements of spatial velocity correlations that show a clear dependence on the mechanism of energy injection. We also report new measurements of the velocity autocorrelation function in the granular layer and show that increased inelasticity leads to enhanced particle self-diffusion.Comment: 11 pages, 7 figure

Self similar Barkhausen noise in magnetic domain wall motion

A model for domain wall motion in ferromagnets is analyzed. Long-range magnetic dipolar interactions are shown to give rise to self-similar dynamics when the external magnetic field is increased adiabatically. The power spectrum of the resultant Barkhausen noise is of the form $1/\omega^\alpha$, where $\alpha\approx 1.5$ can be estimated from the critical exponents for interface depinning in random media.Comment: 7 pages, RevTex. To appear in Phys. Rev. Let

Non-equilibrium two-phase coexistence in a confined granular layer

We report the observation of the homogenous nucleation of crystals in a dense layer of steel spheres confined between two horizontal plates vibrated vertically. Above a critical vibration amplitude, two-layer crystals with square symmetry were found to coexist in steady state with a surrounding granular liquid. By analogy to equilibrium hard sphere systems, the phase behavior can be explained through entropy maximization. However, dramatic non-equilibrium effects are present, including a significant difference in the granular temperatures of the two phases.Comment: 4 pages, 3 figures, RevTex4 forma

Growth and maturation of Korean chum salmon under changing environmental conditions

Salmon populations in the North Pacific have been subject to major changes in environment and fishing pressure since the early 1980s, including a climate regime shift in 1988-89, the closure of the high-seas fisheries in 1993, and a subsequent climatic event in 1998. In the present work, we evaluate whether any of these three events has triggered changes in the life-history traits of chum salmon (Oncorhynchus keta) from the Namdae River, on the eastern coast of South Korea, using data collected on females and males from 1984 to 2008. We find that the 1988-89 regime shift had the most pervasive effects on female and male maturation schedules and growth. We also demonstrate sex-specific responses: whereas growth showed similar patterns of variation in both sexes, age and length at maturation behaved differently in males and females. Our findings contribute to growing evidence that abrupt transitions in climatic conditions can trigger detectable changes in life-history traits. They also strengthen the observation that biological records of salmon populations of the North Pacific carry a stronger signal for the effects of the 1988-89 regime shift than for the effects of the subsequent environmental changes

A first look at maximally twisted mass lattice QCD calculations at the physical point

In this contribution, a first look at simulations using maximally twisted mass Wilson fermions at the physical point is presented. A lattice action including clover and twisted mass terms is presented and the Monte Carlo histories of one run with two mass-degenerate flavours at a single lattice spacing are shown. Measurements from the light and heavy-light pseudoscalar sectors are compared to previous $N_f = 2$ results and their phenomenological values. Finally, the strategy for extending simulations to $N_f = 2 + 1 + 1$ is outlined.Comment: presented at the 31st International Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, German

Renormalization constants of local operators for Wilson type improved fermions

Perturbative and non-perturbative results are presented on the renormalization constants of the quark field and the vector, axial-vector, pseudoscalar, scalar and tensor currents. The perturbative computation, carried out at one-loop level and up to second order in the lattice spacing, is performed for a fermion action, which includes the clover term and the twisted mass parameter yielding results that are applicable for unimproved Wilson fermions, as well as for improved clover and twisted mass fermions. We consider ten variants of the Symanzik improved gauge action corresponding to ten different values of the plaquette coefficients. Non-perturbative results are obtained using the twisted mass Wilson fermion formulation employing two degenerate dynamical quarks and the tree-level Symanzik improved gluon action. The simulations are performed for pion masses in the range of 480 MeV to 260 MeV and at three values of the lattice spacing, a, corresponding to beta=3.9, 4.05, 4.20. For each renormalization factor computed non-perturbatively we subtract its perturbative O(a^2) terms so that we eliminate part of the cut-off artifacts. The renormalization constants are converted to MS-bar at a scale of mu=2 GeV. The perturbative results depend on a large number of parameters and are made easily accessible to the reader by including them in the distribution package of this paper, as a Mathematica input file.Comment: 36 pages, 11 figures and 6 tables. The results are included in electronic form (Mathematica files

Indications for pediatric liver transplantation

Two hundred fifty pediatric (<18 years of age) patients underwent orthotopic liver transplantation because of end-stage liver disease and were given combination therapy with cyclosporine and prednisone. The most common indications for transplantation in decreasing order of frequency were biliary atresia, inborn errors of metabolism, and postnecrotic cirrhosis. The 5-year actuarial survival for the entire group was 69.2%. Age and diagnosis did not influence survival. Infections were the most common cause of death, followed by liver failure and cerebrovascular accident. The impact of retransplantation on survival depends on the indication. The survival is better when retransplantation is carried out after rejection than because of technical complications, and the latter has a better survival than does primary graft nonfunction. The difference in survival among these groups is statistically significant. The quality of life for 164 of 173 survivors is good to excellent; only nine children are currently experiencing medical problems. A persistent problem in pediatric transplantation is the scarcity of small donors. © 1987 The C. V. Mosby Company

True Superconductivity in a 2D "Superconducting-Insulating" System

We present results on disordered amorphous films which are expected to undergo a field-tuned Superconductor-Insulator Transition. Based on low-field data and I-V characteristics, we find evidence of a low temperature Metal-to-Superconductor transition. This transition is characterized by hysteretic magnetoresistance and discontinuities in the I-V curves. The metallic phase just above the transition is different from the "Fermi Metal" before superconductivity sets in.Comment: 3 pages, 4 figure