Augmentor emissions reduction technology program

Technology to reduce pollutant emissions from duct-burner-type augmentors for use on advanced supersonic cruise aircraft was investigated. Test configurations, representing variations of two duct-burner design concepts, were tested in a rectangular sector rig at inlet temperature and pressure conditions corresponding to takeoff, transonic climb, and supersonic cruise flight conditions. Both design concepts used piloted flameholders to stabilize combustion of lean, premixed fuel/air mixtures. The concepts differed in the flameholder type used. High combustion efficiency (97%) and low levels of emissions (1.19 g/kg fuel) were achieved. The detailed measurements suggested the direction that future development efforts should take to obtain further reductions in emission levels and associated improvements in combustion efficiency over an increased range of temperature rise conditions

Genus Topology of the Cosmic Microwave Background from the WMAP 3-Year Data

We have independently measured the genus topology of the temperature fluctuations in the cosmic microwave background seen in the Wilkinson Microwave Anisotropy Probe (WMAP) 3-year data. A genus analysis of the WMAP data indicates consistency with Gaussian random-phase initial conditions, as predicted by standard inflation. We set 95% confidence limits on non-linearities of -101 < f_{nl} < 107. We also find that the observed low l (l <= 8) modes show a slight anti-correlation with the Galactic foreground, but not exceeding 95% confidence, and that the topology defined by these modes is consistent with that of a Gaussian random-phase distribution (within 95% confidence).Comment: MNRAS LaTeX style (mn2e.cls), EPS and JPEG figure

Towards Locating the Brightest Microlensing Events on the Sky

It is estimated that a star brighter than visual magnitude 17 is undergoing a detectable gravitational microlensing event, somewhere on the sky, at any given time. It is assumed that both lenses and sources are normal stars drawn from a standard Bahcall-Soneira model of our Galaxy. Furthermore, over the time scale of a year, a star 15th magnitude or brighter should undergo a detectable gravitational lens amplification. Detecting and studying the microlensing event rate among the brightest 10$^8$ stars could yield a better understanding of Galactic stellar and dark matter distributions. Diligent tracking of bright microlensing events with even small telescopes might detect planets orbiting these stellar lenses.Comment: 19 pages, 4 figures, accepted by Ap

Formality and informality in the summative assessment of motor vehicle apprentices: a case study

This article explores the interaction of formal and informal attributes of competence‐based assessment. Specifically, it presents evidence from a small qualitative case study of summative assessment practices for competence‐based qualifications within apprenticeships in the motor industry in England. The data are analysed through applying an adaptation of a framework for exploring the interplay of formality and informality in learning. This analysis reveals informal mentoring as a significant element which influences not only the process of assessment, but also its outcomes. We offer different possible interpretations of the data and their analysis, and conclude that, whichever interpretation is adopted, there appears to be a need for greater capacity‐building for assessors at a local level. This could acknowledge a more holistic role for assessors; recognise the importance of assessors’ informal practices in the formal retention and achievement of apprentices; and enhance awareness of inequalities that may be reinforced by both informal and formal attributes of assessment practices

Effects of Foreground Contamination on the Cosmic Microwave Background Anisotropy Measured by MAP

We study the effects of diffuse Galactic, far-infrared extragalactic source, and radio point source emission on the cosmic microwave background (CMB) anisotropy data anticipated from the MAP experiment. We focus on the correlation function and genus statistics measured from mock MAP foreground-contaminated CMB anisotropy maps generated in a spatially-flat cosmological constant dominated cosmological model. Analyses of the simulated MAP data at 90 GHz (0.3 deg FWHM resolution smoothed) show that foreground effects on the correlation function are small compared with cosmic variance. However, the Galactic emission, even just from the region with |b| > 20 deg, significantly affects the topology of CMB anisotropy, causing a negative genus shift non-Gaussianity signal. Given the expected level of cosmic variance, this effect can be effectively reduced by subtracting existing Galactic foreground emission models from the observed data. IRAS and DIRBE far-infrared extragalactic sources have little effect on the CMB anisotropy. Radio point sources raise the amplitude of the correlation function considerably on scales below 0.5 deg. Removal of bright radio sources above a 5 \sigma detection limit effectively eliminates this effect. Radio sources also result in a positive genus curve asymmetry (significant at 2 \sigma) on 0.5 deg scales. Accurate radio point source data is essential for an unambiguous detection of CMB anisotropy non-Gaussianity on these scales. Non-Gaussianity of cosmological origin can be detected from the foreground-subtracted CMB anisotropy map at the 2 \sigma level if the measured genus shift parameter |\Delta\nu| >= 0.02 (0.04) or if the measured genus asymmetry parameter |\Delta g| >= 0.03 (0.08) on a 0.3 (1.0) deg FWHM scale.Comment: 26 pages, 7 figures, Accepted for Publication in Astrophysical Journal (Some sentences and figures modified

A New Microlensing Event in the Doubly-Imaged Quasar Q0957+561

We present evidence for ultraviolet/optical microlensing in the gravitationally lensed quasar Q0957+561. We combine new measurements from our optical monitoring campaign at the United States Naval Observatory, Flagstaff (USNO) with measurements from the literature and find that the time-delay-corrected r-band flux ratio m_A - m_B has increased by ~0.1 magnitudes over a period of five years beginning in the fall of 2005. We apply our Monte Carlo microlensing analysis procedure to the composite light curves, obtaining a measurement of the optical accretion disk size, log {(r_s/cm)[cos(i)/0.5]^{1/2}} = 16.2^{+0.5}_{-0.6}, that is consistent with the quasar accretion disk size - black hole mass relation.Comment: Replaced with accepted version. Minor adjustments to text but conclusions unchanged. Data in Table 2 have been updated and table now includes additional observation

Reef Coral Reproduction in the Eastern Pacific: Costa Rica, Panamá, and the Galápagos Islands (Ecuador). VI. Agariciidae, Pavona clavus

The reproductive ecology of the zooxanthellate reef coral Pavona clavus was investigated at several sites in Costa Rica, Panama, and the Galapagos Islands (Ecuador) over the period 1985–2009. Pavona clavus displayed stable gonochorism as only five hermaphrodites were found in 590 samples. At four of five locations, sex ratios were skewed toward female dominance; however, at Saboga Island (Panama) male colonies predominated. In Panama, sexual maturity was observed in an estimated eight year old female colony, and several colonies of 10–20 years of age demonstrated gametogenesis. Sexual activity was observed at all study sites, but gamete development occurred in only 14–31% of colonies sampled sporadically. Seasonality of gametogenic activity occurred predominantly during the warm/wet season, June to August, at mainland sites (Cano Island, Costa Rica, and Gulfs of Chiriqui and Panama, Panama). This pattern was repeated in the Galapagos Islands, but mainly from March to May when seasonally high sea temperatures and rainfall prevailed there. Histological sampling and field observations indicated that spawning was centered around the full moon, most frequently on lunar day 17, and near sunset (1,800 h). Mean fecundity (mature ova cm-2 live tissue) estimates were significantly different for two sites and ranged from ~1,780 (Saboga Island, Gulf of Panama, seasonally upwelling) to ~4,280 (Uva Is, Gulf of Chiriqui, nonupwelling). Assuming three annual spawning events colony-1 (August, September, October), extrapolation of minimum and maximum fecundities yield 5,340 and 12,840 ova cm-2 year-1. Seasonal, lunar, and diel spawning patterns in nine zooxanthellate species at Uva Island indicate asynchronous coral community spawning

Topology of structure in the Sloan Digital Sky Survey: model testing

We measure the three-dimensional topology of large-scale structure in the Sloan Digital Sky Survey (SDSS). This allows the genus statistic to be measured with unprecedented statistical accuracy. The sample size is now sufficiently large to allow the topology to be an important tool for testing galaxy formation models. For comparison, we make mock SDSS samples using several state-of-the-art N-body simulations: the Millennium run of Springel et al. (2005)(10 billion particles), Kim & Park (2006) CDM models (1.1 billion particles), and Cen & Ostriker (2006) hydrodynamic code models (8.6 billion cell hydro mesh). Each of these simulations uses a different method for modeling galaxy formation. The SDSS data show a genus curve that is broadly characteristic of that produced by Gaussian random phase initial conditions. Thus the data strongly support the standard model of inflation where Gaussian random phase initial conditions are produced by random quantum fluctuations in the early universe. But on top of this general shape there are measurable differences produced by non-linear gravitational effects (cf. Matsubara 1994), and biasing connected with galaxy formation. The N-body simulations have been tuned to reproduce the power spectrum and multiplicity function but not topology, so topology is an acid test for these models. The data show a ``meatball'' shift (only partly due to the Sloan Great Wall of Galaxies; this shift also appears in a sub-sample not containing the Wall) which differs at the 2.5\sigma level from the results of the Millennium run and the Kim & Park dark halo models, even including the effects of cosmic variance.Comment: 13 Apj pages, 7 figures High-resolution stereo graphic available at http://www.astro.princeton.edu/~dclayh/stereo50.ep