Nature of fault planes in solid neutron star matter

The properties of tectonic earthquake sources are compared with those deduced here for fault planes in solid neutron-star matter. The conclusion that neutron-star matter cannot exhibit brittle fracture at any temperature or magnetic field is significant for current theories of pulsar glitches, and of the anomalous X-ray pulsars and soft-gamma repeaters.Comment: 5 AAS LaTeX pages 1 eps figur

Tricritical Phenomena at the Cerium γ→α\gamma \to \alpha Transition

The $\gamma \to \alpha$ isostructural transition in the Ce$_{0.9-x}$La$_x$Th$_{0.1}$ system is measured as a function of La alloying using specific heat, magnetic susceptibility, resistivity, thermal expansivity/striction measurements. A line of discontinuous transitions, as indicated by the change in volume, decreases exponentially from 118 K to close to zero with increasing La doping and the transition changes from being first-order to continuous at a critical concentration $0.10 \leq x_c \leq 0.14$. At the tricritical point, the coefficient of the linear $T$ term in the specific heat $\gamma$ and the magnetic susceptibility start to increase rapidly near $x$ = 0.14 and gradually approaches large values at $x$=0.35 signifying that a heavy Fermi-liquid state evolves at large doping. Near $x_c$, the Wilson ratio, $R_W$, has a value of 3.0, signifying the presence of magnetic fluctuations. Also, the low-temperature resistivity shows that the character of the low-temperature Fermi-liquid is changing

On the correlation between fragility and stretching in glassforming liquids

We study the pressure and temperature dependences of the dielectric relaxation of two molecular glassforming liquids, dibutyl phtalate and m-toluidine. We focus on two characteristics of the slowing down of relaxation, the fragility associated with the temperature dependence and the stretching characterizing the relaxation function. We combine our data with data from the literature to revisit the proposed correlation between these two quantities. We do this in light of constraints that we suggest to put on the search for empirical correlations among properties of glassformers. In particular, argue that a meaningful correlation is to be looked for between stretching and isochoric fragility, as both seem to be constant under isochronic conditions and thereby reflect the intrinsic effect of temperature

Complete pressure dependent phase diagrams for SrFe2As2 and BaFe2As2

The temperature dependent electrical resistivity of single crystalline SrFe2As2 and BaFe2As2 has been measured in a liquid medium, modified Bridgman anvil cell for pressures in excess of 75 kbar. These data allow for the determination of the pressure dependence of the higher temperature, structural / antiferromagnetic phase transitions as well as the lower temperature superconducting phase transition. For both compounds the ambient pressure, higher temperature structural / antiferromagnetic phase transition can be fully suppressed with a dome-like region of zero resistivity found to be centered about its critical pressure. Indeed, qualitatively, the temperature dependence of the resistivity curves closest to the critical pressures are the closest to linear, consistent with possible quantum criticality. For pressures significantly higher than the critical pressure the zero resistivity state is suppressed and the low temperature resistivity curves asymptotically approach a universal, low temperature manifold. These results are consistent with the hypothesis that correlations / fluctuations associated with the ambient-pressure, high-temperature, tetragonal phase have to be brought to low enough temperature to allow superconductivity, but if too fully suppressed can lead to the loss of the superconducting state

Positive-Operator-Valued Time Observable in Quantum Mechanics

We examine the longstanding problem of introducing a time observable in Quantum Mechanics; using the formalism of positive-operator-valued measures we show how to define such an observable in a natural way and we discuss some consequences.Comment: 13 pages, LaTeX, no figures. Some minor changes, expanded the bibliography (now it is bigger than the one in the published version), changed the title and the style for publication on the International Journal of Theoretical Physic

Density scaling and quasiuniversality of flow-event statistics for athermal plastic flows

Athermal plastic flows were simulated for the Kob-Andersen binary Lennard-Jones system and its repulsive version in which the sign of the attractive terms is changed to a plus. Properties evaluated from simulations at different densities include the distributions of energy drops, stress drops, and strain intervals between the flow events. By reference to hidden scale invariance we show that simulations at a single density in conjunction with an equilibrium-liquid simulation at the same density allows one to predict the plastic flow-event properties at other densities. We furthermore demonstrate quasiuniversality of the flow-event statistics