Is the World After All Just a Dream?

DocPerform is a multi and interdisciplinary research project based at City, University of London. Led by members of the Department of Library & Information Science, it comprises scholars and practitioners from the fields of performing arts and library & information science. The project concerns conceptual, methodological and technological innovations in the documentation of performance, and the extent to which performance may itself be considered to be a document. The collection of papers in this special issue of Proceedings from the Document Academy are selected from the second DocPerform Symposium, held at City, University of London, 6–7 November 2017. This editorial introduces those papers and provides disciplinary and historical context for DocPerform

The SCUBA Local Universe Galaxy Survey

The SCUBA local universe galaxy survey is the first systematic survey of the local universe at submillimetre wavelengths. We have observed ~200 galaxies from the IRAS bright galaxy catalogue and the CfA optical redshift survey. The IRAS sample showed that our estimate of the luminosity function was potentially biased if a cold population of galaxies existed which would not have appeared in the IRAS BGS but would have been detected in a SCUBA blind survey. Here we present preliminary results from the optically selected sample which suggest that this is indeed the case.Comment: 2 pages, 2 figs, proceedings from Euro-conference on galaxy evolution held in La Reunion, 200

Balanced filters for the analysis of Al, Si, K, Ca, Fe, and Ni

Balanced filters evaluated for performance in X-ray fluorescence analysis of lunar and planetary surface material

Symmetry protected fractional Chern insulators and fractional topological insulators

In this paper we construct fully symmetric wavefunctions for the spin-polarized fractional Chern insulators (FCI) and time-reversal-invariant fractional topological insulators (FTI) in two dimensions using the parton approach. We show that the lattice symmetry gives rise to many different FCI and FTI phases even with the same filling fraction $\nu$ (and the same quantized Hall conductance $\sigma_{xy}$ in FCI case). They have different symmetry-protected topological orders, which are characterized by different projective symmetry groups. We mainly focus on FCI phases which are realized in a partially filled band with Chern number one. The low-energy gauge groups of a generic $\sigma_{xy}=1/m\cdot e^2/h$ FCI wavefunctions can be either $SU(m)$ or the discrete group $Z_m$, and in the latter case the associated low-energy physics are described by Chern-Simons-Higgs theories. We use our construction to compute the ground state degeneracy. Examples of FCI/FTI wavefunctions on honeycomb lattice and checkerboard lattice are explicitly given. Possible non-Abelian FCI phases which may be realized in a partially filled band with Chern number two are discussed. Generic FTI wavefunctions in the absence of spin conservation are also presented whose low-energy gauge groups can be either $SU(m)\times SU(m)$ or $Z_m\times Z_m$. The constructed wavefunctions also set up the framework for future variational Monte Carlo simulations.Comment: 24 pages, 13 figures, published versio

Exotic plasma as classical Hall Liquid

A non-relativistic plasma model endowed with an ``exotic'' structure associated with the two-parameter central extension of the planar Galilei group is constructed. Introducing a Chern-Simons statistical gauge field provides us with a self-consistent system; when the magnetic field takes a critical value determined by the extension parameters, the fluid becomes incompressible and moves collectively, according to the Hall law.Comment: 11 pages, LaTex, no figures. Revised version: Some details better explained. To appear in Int. Journ. Mod. Phys.

B2 and G2 Toda systems on compact surfaces: a variational approach

We consider the B2 and G2 Toda systems on compact surfaces. We attack the problem using variational techniques. We get existence and multiplicity of solutions under a topological assumption on the surface and some generic conditions on the parameters. We also extend some of the results to the case of general systems.Comment: 28 pages, accepted on Journal of Mathematical Physic

The SCUBA Local Universe Galaxy Survey I: First Measurements of the Submillimetre Luminosity and Dust Mass Functions

We have used SCUBA to observe a complete sample of 104 galaxies selected at 60 microns from the IRAS BGS and we present here the 850 micron measurements. Fitting the 60,100 and 850 micron fluxes with a single temperature dust model gives the sample mean temperature T=36 K and beta = 1.3. We do not rule out the possibility of dust which is colder than this, if a 20 K component was present then our dust masses would increase by factor 1.5-3. We present the first measurements of the luminosity and dust mass functions, which were well fitted by Schechter functions (unlike those 60 microns). We have correlated many global galaxy properties with the submillimetre and find that there is a tendancy for less optically luminous galaxies to contain warmer dust and have greater star formation efficiencies (cf. Young 1999). The average gas-to-dust ratio for the sample is 581 +/- 43 (using both atomic and molecular hydrogen), significantly higher than the Galactic value of 160. We believe this discrepancy is due to a cold dust component at T < 20 K. There is a suprisingly tight correlation between dust mass and the mass of molecular hydrogen as estimated from CO measurements, with an intrinsic scatter of ~50%.Comment: 24 pages, 15 figures, 8 tables, accepted for publication in MNRA

A Gauge-Gravity Relation in the One-loop Effective Action

We identify an unusual new gauge-gravity relation: the one-loop effective action for a massive spinor in 2n dimensional AdS space is expressed in terms of precisely the same function [a certain multiple gamma function] as the one-loop effective action for a massive charged scalar in 4n dimensions in a maximally symmetric background electromagnetic field [one for which the eigenvalues of F_{\mu\nu} are maximally degenerate, corresponding in 4 dimensions to a self-dual field, equivalently to a field of definite helicity], subject to the identification F^2 \Lambda, where \Lambda is the gravitational curvature. Since these effective actions generate the low energy limit of all one-loop multi-leg graviton or gauge amplitudes, this implies a nontrivial gauge-gravity relation at the non-perturbative level and at the amplitude level.Comment: 6 page

Gravitational non-commutativity and G\"odel-like spacetimes

We derive general conditions under which geodesics of stationary spacetimes resemble trajectories of charged particles in an electromagnetic field. For large curvatures (analogous to strong magnetic fields), the quantum mechanicical states of these particles are confined to gravitational analogs of {\it lowest Landau levels}. Furthermore, there is an effective non-commutativity between their spatial coordinates. We point out that the Som-Raychaudhuri and G\"odel spacetime and its generalisations are precisely of the above type and compute the effective non-commutativities that they induce. We show that the non-commutativity for G\"odel spacetime is identical to that on the fuzzy sphere. Finally, we show how the star product naturally emerges in Som-Raychaudhuri spacetimes.Comment: Two sections added (Relation to the fuzzy sphere, Emergence of the star product). 10 pages, Revtex. To appear in General Relativity and Gravitatio