EBSD mapping of herringbone domain structures in tetragonal piezoelectrics

Herringbone domain structures have been mapped using electron backscatter diffraction (EBSD) in two tetragonal piezoelectrics, lead zirconate titanate, [Pb(Zr,Ti)O<sub>3</sub>] and bismuth ferrite – lead titanate, [(PbTi)<sub>0.5</sub>(BiFe)<sub>0.5</sub>O<sub>3</sub>]. Analysis of the domain misorientations across the band junctions shows that the structures correspond very well to crystallographic models. High resolution mapping with a 20 nm step size allowed the crystal rotation across one of these band junctions in lead zirconate titanate to be studied in detail and allowed an improved estimation of the peak strain at the junction, of 0.56 GPa. The significance of this for crack nucleation and propagation in such materials is discussed

Precision measurement with an optical Josephson junction

We study a new type of Josephson device, the so-called "optical Josephson junction" as proposed in Phys. Rev. Lett. {\bf 95}, 170402 (2005). Two condensates are optically coupled through a waveguide by a pair of Bragg beams. This optical Josephson junction is analogous to the usual Josephson junction of two condensates weakly coupled via tunneling. We discuss the use of this optical Josephson junction, for making precision measurements.Comment: 6 pages, 1 figur

Partitioning of K, U, and Th between sulfide and silicate liquids: Implications for radioactive heating of planetary cores

The possibility of heating of planetary cores by K radioactivity has been extensively discussed, as well as the possibility that K partitioning into the terrestrial core is the reason for the difference between the terrestrial and chondritic K/U. We had previously suggested that U and Th partitioning into FeFeS liquids was more important than K. Laboratory FeFeS liquid, silicate liquid partition coefficient measurements (D) for K, U, and Th were made to test this suggestion. For a basaltic liquid at 1450°C and 1.5 GPa, D_U is 0.013 and D_K is 0.0026; thus U partitioning into FeFeS liquids is 5 times greater than K partitioning under these conditions. There are problems with 1-atm experiments in that they do not appear to equilibrate or reverse. However, measurable U and Th partitioning into sulfide was nearly always observed, but K partitioning was normally not observed (D_K ≲ 10^(−4)). A typical value for D_U from a granitic silicate liquid at one atmosphere, 1150°C, and low f0_2 is about 0.02; D_(Th) is similar. At low f0_2 and higher temperature, experiments with basaltic liquids produce strong Ca and U partitioning into the sulfide liquid with D_U > 1. D_(Th) is less strongly affected. Because of the consistently low D_K/D_U, pressure effects near the core-mantle boundary would need to increase D_U by factors of ∼10^3 with much smaller increases in DU in order to have the terrestrial K and U abundances at chondritic levels. In addition, if radioactive heating is important for planetary cores, U and Th will be more important than K unless the lower mantle has K/U greater than 10 times chondritic or large changes in partition coefficients with conditions reverse the relative importance of K versus U and Th from our measurements

Extreme Pu-U and Possible Pu-REE Fractionation in Unequilibrated Chondrites

The purpose of this study is to understand actinide chemistry in chondrites and to evaluate unequilibrated chondrites for either Pu/U or Pu/Nd chronology. Using fission track radiography for Nadiabondi (H5/(Murrell and Burnett, 1982), Dhajala (H3,4), Bremervorde (H3), Sharps (H3), and Tieschitz (H3), we find that U is primarily located in chondrule glass (50-500 ppb, average of ~ 100 ppb). Apatite from the unequilibrated chondrites contains 150-200 ppb U while whitlockite contains < 17 ppb [low compared to type-6 chondrites which have 1-6 ppm U in apatite and ~ 200 ppb in whitlockite (Pellas and Storzer, 1975)]. Nadiabondi phosphates are intermediate (Murrell and Burnett, 1982). These observations suggest that the phosphate U content increases with petrologic type (Pellas and Storzer, 1975), with U obtained from chondrule glass during metamorphism

Modeling the non-recycled Fermi gamma-ray pulsar population

We use Fermi Gamma-ray Space Telescope detections and upper limits on non-recycled pulsars obtained from the Large Area Telescope (LAT) to constrain how the gamma-ray luminosity L depends on the period P and the period derivative \dot{P}. We use a Bayesian analysis to calculate a best-fit luminosity law, or dependence of L on P and \dot{P}, including different methods for modeling the beaming factor. An outer gap (OG) magnetosphere geometry provides the best-fit model, which is L \propto P^{-a} \dot{P}^{b} where a=1.36\pm0.03 and b=0.44\pm0.02, similar to but not identical to the commonly assumed L \propto \sqrt{\dot{E}} \propto P^{-1.5} \dot{P}^{0.5}. Given upper limits on gamma-ray fluxes of currently known radio pulsars and using the OG model, we find that about 92% of the radio-detected pulsars have gamma-ray beams that intersect our line of sight. By modeling the misalignment of radio and gamma-ray beams of these pulsars, we find an average gamma-ray beaming solid angle of about 3.7{\pi} for the OG model, assuming a uniform beam. Using LAT-measured diffuse fluxes, we place a 2{\sigma} upper limit on the average braking index and a 2{\sigma} lower limit on the average surface magnetic field strength of the pulsar population of 3.8 and 3.2 X 10^{10} G, respectively. We then predict the number of non-recycled pulsars detectable by the LAT based on our population model. Using the two-year sensitivity, we find that the LAT is capable of detecting emission from about 380 non-recycled pulsars, including 150 currently identified radio pulsars. Using the expected five-year sensitivity, about 620 non-recycled pulsars are detectable, including about 220 currently identified radio pulsars. We note that these predictions significantly depend on our model assumptions.Comment: 26 pages, 10 figures, Accepted by ApJ on 8 September 201

Investigating source confusion in PMN J1603−-4904

PMN J1603$-$4904 is a likely member of the rare class of $\gamma$-ray emitting young radio galaxies. Only one other source, PKS 1718$-$649, has been confirmed so far. These objects, which may transition into larger radio galaxies, are a stepping stone to understanding AGN evolution. It is not completely clear how these young galaxies, seen edge-on, can produce high-energy $\gamma$-rays. PMN J1603$-$4904 has been detected by TANAMI Very Long Baseline Interferometry (VLBI) observations and has been followed-up with multiwavelength observations. A Fermi/LAT $\gamma$-ray source has been associated with it in the LAT catalogs. We have obtained Chandra observations of the source in order to consider the possibility of source confusion, due to the relatively large positional uncertainty of Fermi/LAT. The goal was to investigate the possibility of other X-ray bright sources in the vicinity of PMN J1603$-$4904 that could be counterparts to the $\gamma$-ray emission. With Chandra/ACIS, we find no other sources in the uncertainty ellipse of Fermi/LAT data, which includes an improved localization analysis of 8 years of data. We further study the X-ray fluxes and spectra. We conclude that PMN J1603$-$4904 is indeed the second confirmed $\gamma$-ray bright young radio galaxy.Comment: 4 pages, 3 figures, accepted for publication in A&

Entanglement between atomic condensates in an optical lattice: effects of interaction range

We study the area-dependent entropy and two-site entanglement for two state Bose-Einstein condensates in a 2D optical lattice. We consider the case where the array of two component condensates behave like an ensemble of spin-half particles with the interaction to its nearest neighbors and next nearest neighbors. We show how the Hamiltonian of their Bose-Einstein condensate lattice with nearest-neighbor and next-nearest-neighbor interactions can be mapped into a harmonic lattice. We use this to determine the entropy and entanglement content of the lattice.Comment: 5 pages, 3 figures, title change

Since 1843: in the making, 8 January - 7 February 2014

Catalogue published to accompany the exhibition of the same name held at Nottingham Trent University (Newton, Bonington and Waverley buildings) from 8 January-7 February 2014. The exhibition commenced a series of events to celebrate the 170th anniversary of what in 1843 was named the Nottingham School of Design, and is now the School of Art & Design at Nottingham Trent University

Tell me more?: the effects of mental model soundness on personalizing an intelligent agent

What does a user need to know to productively work with an intelligent agent? Intelligent agents and recommender systems are gaining widespread use, potentially creating a need for end users to understand how these systems operate in order to fix their agent's personalized behavior. This paper explores the effects of mental model soundness on such personalization by providing structural knowledge of a music recommender system in an empirical study. Our findings show that participants were able to quickly build sound mental models of the recommender system's reasoning, and that participants who most improved their mental models during the study were significantly more likely to make the recommender operate to their satisfaction. These results suggest that by helping end users understand a system's reasoning, intelligent agents may elicit more and better feedback, thus more closely aligning their output with each user's intentions