Signal-to-Noise Eigenmode Analysis of the Two-Year COBE Maps

To test a theory of cosmic microwave background fluctuations, it is natural to expand an anisotropy map in an uncorrelated basis of linear combinations of pixel amplitudes --- statistically-independent for both the noise and the signal. These $S/N$-eigenmodes are indispensible for rapid Bayesian analyses of anisotropy experiments, applied here to the recently-released two-year COBE {\it dmr} maps and the {\it firs} map. A 2-parameter model with an overall band-power and a spectral tilt $\nu_{\Delta T}$ describes well inflation-based theories. The band-powers for {\it all} the {\it dmr} $53,90,31$ $a$+$b$ GHz and {\it firs} 170 GHz maps agree, $\{(1.1\pm 0.1)\times 10^{-5}\}^{1/2}$, and are largely independent of tilt and degree of (sharp) $S/N$-filtering. Further, after optimal $S/N$-filtering, the {\it dmr} maps reveal the same tilt-independent large scale features and correlation function. The unfiltered {\it dmr} $53$ $a$+$b$ index $\nu_{\Delta T}+1$ is $1.4\pm 0.4$; increasing the $S/N$-filtering gives a broad region at (1.0--1.2)$\pm$0.5, a jump to (1.4--1.6)$\pm$0.5, then a drop to 0.8, the higher values clearly seen to be driven by $S/N$-power spectrum data points that do not fit single-tilt models. These indices are nicely compatible with inflation values ($\sim$0.8--1.2), but not overwhelmingly so.Comment: submitted to Phys.Rev.Letters, 4 pages, uuencoded compressed PostScript; also bdmr2.ps.Z, via anonymous ftp to ftp.cita.utoronto.ca, cd to /pub/dick/yukawa; CITA-94-2

Mixed tenure orthodoxy: practitioner reflections on policy effects

This article examines mixed tenure as a policy orthodoxy. It first sets out how mixed tenure may be considered to constitute an orthodoxy within planning, being generally accepted as a theory and practice even in the absence of supporting evidence. Five elements of this orthodoxy are identified, relating to (1) housing and the environment, (2) social change, (3) economic impacts, (4) sustainable communities, (5) and sociospatial integration. Interviews with practitioners involved with three social housing estates that have experienced mixed-tenure policy interventions are reported to consider why the implementation and effects of mixed tenure might not correspond with the orthodox understanding. It is argued that policy ambiguity and weaknesses in policy theory and specification, alongside practical constraints, lie behind incomplete and counterproductive policy implementation, but a belief in pursuing the policy orthodoxy persists nevertheless

Arkansas Soybean Performance Tests 2008

Soybean cultivar performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies developing cultivars and/or marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for soybean producer

Arkansas Soybean Performance Tests 2007

Soybean cultivar performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies developing cultivars and/or marketing seed within the State, and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for soybean producers

Arkansas Corn and Grain Sorghum Performance Tests 2003

Corn and grain sorghum performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating recommendations for producers

CMB Likelihood Functions for Beginners and Experts

Although the broad outlines of the appropriate pipeline for cosmological likelihood analysis with CMB data has been known for several years, only recently have we had to contend with the full, large-scale, computationally challenging problem involving both highly-correlated noise and extremely large datasets ($N > 1000$). In this talk we concentrate on the beginning and end of this process. First, we discuss estimating the noise covariance from the data itself in a rigorous and unbiased way; this is essentially an iterated minimum-variance mapmaking approach. We also discuss the unbiased determination of cosmological parameters from estimates of the power spectrum or experimental bandpowers.Comment: Long-delayed submission. In AIP Conference Proceedings "3K Cosmology" held in Rome, Oct 5-10, 1998, edited by Luciano Maiani, Francesco Melchiorri and Nicola Vittorio, 343-347, New York, American Institute of Physics 199

Observation of the dielectric-waveguide mode of light propagation in p-n junctions

Theoretical considerations of the propagation of electromagnetic energy near a p-n junction (1) show that the “sandwich” formed by having a depletion layer bounded by the p and n regions can act as a dielectric waveguide. (1,2

Constraining Large Scale Structure Theories with the Cosmic Background Radiation

We review the relevant 10+ parameters associated with inflation and matter content; the relation between LSS and primary and secondary CMB anisotropy probes; COBE constraints on energy injection; current anisotropy band-powers which strongly support the gravitational instability theory and suggest the universe could not have reionized too early. We use Bayesian analysis methods to determine what current CMB and CMB+LSS data imply for inflation-based Gaussian fluctuations in tilted $\Lambda$CDM, $\Lambda$hCDM and oCDM model sequences with age 11-15 Gyr, consisting of mixtures of baryons, cold (and possibly hot) dark matter, vacuum energy, and curvature energy in open cosmologies. For example, we find the slope of the initial spectrum is within about 5% of the (preferred) scale invariant form when just the CMB data is used, and for $\Lambda$CDM when LSS data is combined with CMB; with both, a nonzero value of $\Omega_\Lambda$ is strongly preferred ($\approx 2/3$ for a 13 Gyr sequence, similar to the value from SNIa). The $o$CDM sequence prefers $\Omega_{tot}<1$, but is overall much less likely than the flat $\Omega_\Lambda \ne 0$ sequence with CMB+LSS. We also review the rosy forecasts of angular power spectra and parameter estimates from future balloon and satellite experiments when foreground and systematic effects are ignored.Comment: 20 pages, LaTeX, 5 figures, 2 tables, uses rspublic.sty To appear in Philosophical Transactions of the Royal Society of London A, 1998. "Discussion Meeting on Large Scale Structure in the Universe," Royal Society, London, March 1998. Text and colour figures also available at ftp://ftp.cita.utoronto.ca/bond/roysoc9

The Exotic Eclipsing Nucleus of the Ring Planetary Nebula SuWt2

SuWt2 is a planetary nebula (PN) consisting of a bright ionized thin ring seen nearly edge-on. It has a bright (V=12) central star, too cool to ionize the PN, which we discovered to be an eclipsing binary. A spectrum from IUE did not reveal a UV source. We present extensive ground-based photometry and spectroscopy of the central binary collected over the ensuing two decades, resulting in the determination that the orbital period of the eclipsing pair is 4.9 d, and consists of two nearly identical A1 V stars, each of mass ~2.7 M_sun. The physical parameters of the A stars, combined with evolutionary tracks, show that both are in the short-lived "blue-hook" evolutionary phase that occurs between the main sequence and the Hertzsprung gap, and that the age of the system is about 520 Myr. One puzzle is that the stars' rotational velocities are different from each other, and considerably slower than synchronous with the orbital period. It is possible that the center-of-mass velocity of the eclipsing pair is varying with time, suggesting that there is an unseen third orbiting body in the system. We propose a scenario in which the system began as a hierarchical triple, consisting of a ~2.9 M_sun star orbiting the close pair of A stars. Upon reaching the AGB stage, the primary engulfed the pair into a common envelope, leading to a rapid contraction of the orbit and catastrophic ejection of the envelope into the orbital plane. In this picture, the exposed core of the initial primary is now a white dwarf of ~0.7 M_sun, orbiting the eclipsing pair, which has already cooled below the detectability possible by IUE at our derived distance of 2.3 kpc and a reddening of E(B-V)=0.40. The SuWt2 system may be destined to perish as a Type Ia supernova. (Abridged)Comment: 60 pages, 11 figure, to appear in the Astronomical Journa

Angular Power Spectrum of the Microwave Background Anisotropy seen by the COBE Differential Microwave Radiometer

The angular power spectrum estimator developed by Peebles (1973) and Hauser & Peebles (1973) has been modified and applied to the 4 year maps produced by the COBE DMR. The power spectrum of the observed sky has been compared to the power spectra of a large number of simulated random skies produced with noise equal to the observed noise and primordial density fluctuation power spectra of power law form, with $P(k) \propto k^n$. The best fitting value of the spectral index in the range of spatial scales corresponding to spherical harmonic indices $3 \leq \ell \lesssim 30$ is an apparent spectral index $n_{app}$ = 1.13 (+0.3) (-0.4) which is consistent with the Harrison-Zel'dovich primordial spectral index $n_{pri} = 1$ The best fitting amplitude for $n_{app} = 1$ is $\langle Q_{RMS}^2\rangle^{0.5}$ = 18 uK.Comment: 17 pages including 3 PostScript figures. Submitted to The Astrophysical Journal (Letters