Resonant systems for dynamic evaluation of pressure transducers

Tests were conducted with contrived inlet modulated sinusoidal pressure generator to study possible use in calibrating pressure sensors. Results indicate concept is feasible and applicable to transducer evaluation

Resonant systems for dynamic transducer evaluations Final report

Resonant systems for dynamic transducer evaluation

Electrovac pppp-waves

New exact solutions of the Einstein-Maxwell field equations that describe $pp$-waves are presented

Symmetry of massive Rarita-Schwinger fields

We derive the general lagrangian and propagator for a vector-spinor field in $d$-dimensions and show that the physical observables are invariant under the so-called point transformation symmetry. Until now the symmetry has not been exploited in any non-trival way, presumably because it is not an invariance of the classical action nor is it a gauge symmetry. Nevertheless, we develop a technique for exploring the consequences of the symmetry leading to a conserved vector current and charge. The current and charge are identically zero in the free field case and only contribute in a background such as a electromagnetic or gravitational field. The current can couple spin-3/2 fields to vector and scalar fields and may have important consequences in intermediate energy hadron physics as well as linearized supergravity. The consistency problem which plagues higher spin field theories is then discussed and and some ideas regarding the possiblity of solutions are presented.Comment: 26 pages, 1 figure; revised using referee comments, Journal ref. adde

Magnetic imaging of layer-by-layer reversal in Co/Pt multilayers with perpendicular anisotropy

For very thin Co layers, the exchange coupling between adjacent Co layers in Co∕Pt multilayers is ferromagnetic and the coupling strength varies nonmonotonically as the nonmagnetic Pt layer thickness (t_Pt) ranges from 3 to 75 Å. We report on the magnetization reversal process in a series of [Co(4 Å)/Pt(t_Pt)]_N multilayers observed by magneto-optical Kerr microscopy as a function of t_Pt and layer repetition N. The images reveal the evolution of magnetic reversal processes that strongly depend on t_Pt and therefore on the interlayer coupling. For Co/Pt multilayers with small t_Pt, e.g., 11 Å, where the Co layers are strongly coupled, the whole multilayer switches as a single ferromagnet. As Co layers are separated farther and become weakly coupled, e.g., at t_Pt=41 Å, layer-by-layer magnetic reversal is observed. The Kerr images reveal metastable magnetic domain configurations during layer-by-layer switching which is not evident in the measured hysteresis loops during the abrupt magnetic reversal for Co∕Pt multilayers with weak interlayer coupling at large t_Pt

Bottlenecks to vibrational energy flow in OCS: Structures and mechanisms

Finding the causes for the nonstatistical vibrational energy relaxation in the planar carbonyl sulfide (OCS) molecule is a longstanding problem in chemical physics: Not only is the relaxation incomplete long past the predicted statistical relaxation time, but it also consists of a sequence of abrupt transitions between long-lived regions of localized energy modes. We report on the phase space bottlenecks responsible for this slow and uneven vibrational energy flow in this Hamiltonian system with three degrees of freedom. They belong to a particular class of two-dimensional invariant tori which are organized around elliptic periodic orbits. We relate the trapping and transition mechanisms with the linear stability of these structures.Comment: 13 pages, 13 figure

Pygmy Sperm Whale (Kogin breiJiceps) stranding record in Tasmania, Australia, and diet of a single specimen

This study describes the stranding record of the Pygmy Sperm Whale, Kogia breviceps, in Tasmanian waters, and the diet of a single individual. The Pygmy Sperm Whale is one of the most commonly stranded cetaceans in some parts of Australia, although it occurs infrequently in the Tasmanian stranding record, with only seven known stranding events. Dietary items were investigated from a single juvenile male Pygmy Sperm Whale stranded in southeast Tasmania. The recoverable diet consisted of approximately three kilograms of reconstructed cephalopod prey mass from at least 11 cephalopod species within nine families. Using reconstructed biomass, the most important family was Histioteuthidae (Histioteuthis atlantica and H. miranda: 29% of reconstructed biomass), followed by Ommastrephidae (unknown sp.: 27% of reconstructed biomass), Enoploteuthidae (Enoploteuthis sp): 25% of reconstructed biomass), Cranchiidae (Cranchia scabra and Teuthowenia pellucida), Chiroteuthidae (Chiroteuthis veranyi), Brachioteuthidae (Brachioteuthis linkovskyi), Neoteuthidae (Nototeuthis dimegacotyle), Pyroteuthidae (Pyroteuthis margaritifera) and Sepiolidae (Heteroteuthis sp.). Collection and analysis of biological material from Pygmy Sperm Whale strandings around Australia should be a high priority to better understand the ecology of this poorly known species