Noise characteristics of upper surface blown configurations: Analytical Studies

Noise and flow results of upper surface blown configurations were analyzed. The dominant noise source mechanisms were identified from experimental data. From far-field noise data for various geometric and operational parameters, an empirical noise prediction program was developed and evaluated by comparing predicted results with experimental data from other tests. USB aircraft compatibility studies were conducted using the described noise prediction and a cruise performance data base. A final design aircraft was selected and theory was developed for the noise from the trailing edge wake assuming it as a highly sheared layer

Undoped Electron-Hole Bilayers in a GaAs/AlGaAs Double Quantum Well

We present the fabrication details of completely undoped electron-hole bilayer devices in a GaAs/AlGaAs double quantum well heterostructure with a 30 nm barrier. These devices have independently tunable densities of the two-dimensional electron gas and two-dimensional hole gas. We report four-terminal transport measurements of the independently contacted electron and hole layers with balanced densities from $1.2 \times 10^{11}$cm$^{-2}$ down to $4 \times 10^{10}$ cm$^{-2}$ at $T = 300 mK$. The mobilities can exceed $1 \times 10^{6}$ cm$^{2}$ V$^{-1}$ s$^{-1}$ for electrons and $4 \times 10^{5}$ cm$^{2}$ V$^{-1}$ s$^{-1}$ for holes.Comment: 3 pages, 3 figure

Specialized visual learning of facial signals of quality in the paper wasp, P olistes dominula

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109618/1/bij12394.pd

Measurement of electron-hole friction in an n-doped GaAs/AlGaAs quantum well using optical transient grating spectroscopy

We use phase-resolved transient grating spectroscopy to measure the drift and diffusion of electron-hole density waves in a semiconductor quantum well. The unique aspects of this optical probe allow us to determine the frictional force between a two-dimensional Fermi liquid of electrons and a dilute gas of holes. Knowledge of electron-hole friction enables prediction of ambipolar dynamics in high-mobility electron systems.Comment: to appear in PR

How Does Individual Recognition Evolve? Comparing Responses to Identity Information in P olistes Species with and Without Individual Recognition

A wide range of complex social behaviors are facilitated by the recognition of individual conspecifics. Individual recognition requires sufficient phenotypic variation to provide identity information as well as receivers that process and respond to identity information. Understanding how a complex trait such as individual recognition evolves requires that we consider how each component has evolved. Previous comparative studies have examined phenotypic variability in senders and receiver learning abilities, although little work has compared receiver responses to identity information among related species with and without individual recognition. Here, we compare responses to identity information in two Polistes paper wasps: P. fuscatus, which visually recognizes individuals, and P. metricus , which does not normally show evidence of individual recognition. Although the species differ in individual recognition, the results of this study show that receiver responses to experimentally manipulated identity information are surprisingly similar in both species. Receivers direct less aggression toward identifiable individuals than unidentifiable individuals. Therefore, the responses necessary for individual recognition may pre‐date its evolution in the P. fuscatus lineage. Additionally, our data demonstrate the apparent binary differences in a complex behavior between the two species, such as individual recognition, likely involve incremental differences along a number of axes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102093/1/eth12191.pd

Evaluation of advanced lift concepts and fuel conservative short-haul aircraft, volume 2

For abstract, see N75-20291

The electronic transport properties and microstructure of carbon nanofiber/epoxy composites

Carbon nanofibres (CNF) were dispersed into an epoxy resin using a combination of ultrasonication and mechanical mixing. The electronic transport properties of the resulting composites were investigated by means of impedance spectroscopy. It was found that a very low critical weight fraction (pc = 0.064 wt %) which may be taken to correspond to the formation of a tunneling conductive network inside the matrix. The insulator-to-conductor transition region spanned about one order of magnitude from 0.1 to 1 wt %. Far from the transition, the conductivity increased by two orders of magnitude. This increase and the low value of the conductivity were explained in terms of the presence of an epoxy film at the contact between CNF. A simple model based on the CNF-CNF contact network inside the matrix was proposed in order to evaluate the thickness of that film.Comment: 7 page

Evaluation of advanced lift concepts and fuel conservative short-haul aircraft, volume 1

The performance and economics of a twin-engine augmentor wing airplane were evaluated in two phases. Design aspects of the over-the-wing/internally blown flap hybrid, augmentor wing, and mechanical flap aircraft were investigated for 910 m. field length with parametric extension to other field lengths. Fuel savings achievable by application of advanced lift concepts to short-haul aircraft were evaluated and the effect of different field lengths, cruise requirements, and noise levels on fuel consumption and airplane economics at higher fuel prices were determined. Conclusions and recommendations are presented

Chandra Observation of 3C 212: a New Look at the X-ray and UV Absorbers

The red quasar 3C 212 (z=1.049) is one of the most distant and most luminous AGN which has shown evidence of an X-ray warm absorber. In order to further investigate this unusual quasar, we used Chandra/ACIS-S to observe 3C 212 for 19.5 ksec, resulting in a net detection of ~4000 counts. The Chandra data confirm the presence of an excess absorbing column N_H ~ 4 x 10^21 cm^-2 at the quasar redshift, but we find no compelling evidence for a warm absorber. Using both the Chandra and archival ROSAT PSPC data, we obtain very good fits for both a partially covered neutral absorber and a low-ionization (U = 0.03) photo-ionized absorber. In the ultraviolet, 3C 212 shows a strong associated MgII absorber. Based on a moderate resolution (80 km/s) MMT spectrum we show that the absorber is highly saturated and has a covering fraction less than 60%, implying that the absorber is truly intrinsic to the quasar. Photo-ionization modeling of the MgII absorber yields a constraint on the ionization parameter of U < 0.03, inconsistent with a warm UV/X-ray absorber. In addition to our spectral analysis, we find evidence in the ACIS image data for weak extended emission surrounding the quasar as well as emission corresponding to the radio lobes at a distance of 5 arcsec from 3C 212. The statistical significance of these features is low, but we briefly explore the implications if the detections are valid.Comment: 8 pages, 6 figures, Accepted for publication in the Astrophysical Journa

Theoretical and Experimental Considerations for Neutrinoless Double Beta Decay

In the rst part of this work we show some theoretical aspects of the generation of the neutrino mass by means of a direct extension of the Standard Model of particles, which include the presence of heavy right-handed neutrinos and large Majorana mass terms. From these two new ingredients, it is possible to nd a mass for the light neutrinos which is naturally of the order of 1 eV or less. The idea is to put these theoretical aspects in the context of the search for neutrino mass values by the study of the signal from the Neutrinoless Double Beta Decay Process (0 ). In the second part, a brief summary is given of the experimental considerations required for the measurement of effective Majorana neutrino mass using (0 ). Measurement strategies and background considerations are introduced and an outline of both active and passive methods is given. Finally, current results are discussed with particular emphasis on the HeidelbergMoscow experiment. This note is based on the presentation given at the CERNCLAF 4th Latin American School on High-Energy Physics