The Early to Middle Ordovician graptolite faunal succession of the Trail Creek region, central Idaho, U.S.A

The Middle Ordovician graptolite biostratigraphy of the Trail Creek region of Idaho is reviewed and revised. The oldest known fauna belongs to the Didymograptellus bifidus Biozone. The Isograptus victoriae lunatus, I. victoriae maximodivergens, Oncograptus, Undulograptus austrodentatus and Holmograptus lentus Biozones can be differentiated. Pseudophyllograptus archaios (Braithwaite) is found for the first time in the Trail Creek region. This species represents a conspicuous North American mid-continent faunal element and enables the correlation of the endemic P. archaios-C. flexilis Biozone of Utah with the D. bifidus Biozone of the Pacific faunal realm, thus, providing an important tool for the correlation of endemic mid-continent faunas with the pandemic deep water graptolite faunas

Optimized Confinement of Fermions in Two Dimensions

One of the challenging features of studying model Hamiltonians with cold atoms in optical lattices is the presence of spatial inhomogeneities induced by the confining potential, which results in the coexistence of different phases. This paper presents Quantum Monte Carlo results comparing meth- ods for confining fermions in two dimensions, including conventional diagonal confinement (DC), a recently proposed 'off-diagonal confinement' (ODC), as well as a trap which produces uniform den- sity in the lattice. At constant entropy and for currently accessible temperatures, we show that the current DC method results in the strongest magnetic signature, primarily because of its judicious use of entropy sinks at the lattice edge. For d-wave pairing, we show that a constant density trap has the more robust signal and that ODC can implement a constant density profile. This feature is important to any prospective search for superconductivity in optical lattices

Isentropic Curves at Magnetic Phase Transitions

Experiments on cold atom systems in which a lattice potential is ramped up on a confined cloud have raised intriguing questions about how the temperature varies along isentropic curves, and how these curves intersect features in the phase diagram. In this paper, we study the isentropic curves of two models of magnetic phase transitions- the classical Blume-Capel Model (BCM) and the Fermi Hubbard Model (FHM). Both Mean Field Theory (MFT) and Monte Carlo (MC) methods are used. The isentropic curves of the BCM generally run parallel to the phase boundary in the Ising regime of low vacancy density, but intersect the phase boundary when the magnetic transition is mainly driven by a proliferation of vacancies. Adiabatic heating occurs in moving away from the phase boundary. The isentropes of the half-filled FHM have a relatively simple structure, running parallel to the temperature axis in the paramagnetic phase, and then curving upwards as the antiferromagnetic transition occurs. However, in the doped case, where two magnetic phase boundaries are crossed, the isentrope topology is considerably more complex

Crystallographic Oxide Phase Identification of Char Deposits Obtained from Space Shuttle Columbia Window Debris

Analyzing the remains of Space Shuttle Columbia has proven technically beneficial years after the vehicle breakup. This investigation focused on charred deposits on fragments of Columbia overhead windowpanes. Results were unexpected relative to the engineering understanding of material performance in a reentry environment. The TEM analysis demonstrated that the oxides of aluminum and titanium mixed with silicon oxides to preserve a history of thermal conditions to which portions of the vehicle were exposed. The presence of Ti during the beginning of the deposition process, along with the thermodynamic phase precipitation upon cool down, indicate that temperatures well above the Ti melt point were experienced. The stratified observations implied that additional exothermic reaction, expectedly metal combustion of a Ti structure, had to be present for oxide formation. Results are significant for aerospace vehicles where thermal protection system (TPS) breaches cause substructures to be in direct path with the reentry plasma.

Precision measurement of electronic ion-ion interactions between neighboring Eu3+ optical centers

We report measurements of discrete excitation-induced frequency shifts on the 7F0→5D0 transition of the Eu+ center in La:Lu:EuCl3·6D2O resulting from the optical excitation of neighboring Eu3+ ions. Shifts of up to 46.081±0.005  MHz were observed. The magnitude of the interaction between neighboring ions was found to be significantly larger than expected from the electric dipole-dipole mechanism often observed in rare earth systems. We show that a large network of interacting and individually addressable centers can be created by lightly doping crystals otherwise stoichiometric in the optically active rare earth ion, and that this network could be used to implement a quantum processor with more than ten qubits

Genetic Variation in Perennial Ryegrass for Volatile Fatty Acid Production in Rumen Fluid

In perennial ryegrass genetic variation was shown not only for in vitro organic matter degradation (OMD) in rumen fluid and neutral detergent fibre content (NDF) but also for production of volatile fatty acids (VFAs) upon in vitro incubation in rumen fluid. The correlations among concentrations of VFAs in the incubation fluid were high. OMD and NDF, on the other hand, were poorly correlated to the VFA concentrations