4,622 research outputs found
Accretion of the lowermost oceanic crust at fast-spreading ridges - Basch V., Sanfilippo A., Stracke A., Snow J.E., Zanetti A.
No full textAccretion of the lowermost oceanic crust at fast-spreading ridges - Basch V., Sanfilippo A., Stracke A., Snow J.E., Zanetti A.</p
Computing the fast Fourier transform on SIMD microprocessors
No full textThis thesis describes how to compute the fast Fourier transform (FFT) of a power-of-two length signal on single-instruction, multiple-data (SIMD) microprocessors faster than or very close to the speed of state of the art libraries such as FFTW (“Fastest Fourier Transform in the West”), SPIRAL and Intel Integrated Performance Primitives (IPP).
The conjugate-pair algorithm has advantages in terms of memory bandwidth, and three implementations of this algorithm, which incorporate latency and spatial locality optimizations, are automatically vectorized at the algorithm level of abstraction. Performance results on 2- way, 4-way and 8-way SIMD machines show that the performance scales much better than FFTW or SPIRAL.
The implementations presented in this thesis are compiled into a high-performance FFT library called SFFT (“Streaming Fast Fourier Trans- form”), and benchmarked against FFTW, SPIRAL, Intel IPP and Apple Accelerate on sixteen x86 machines and two ARM NEON machines, and shown to be, in many cases, faster than these state of the art libraries, but without having to perform extensive machine specific calibration, thus demonstrating that there are good heuristics for predicting the performance of the FFT on SIMD microprocessors (i.e., the need for empirical optimization may be overstated)
Examining fast and slow effects for alcohol and negative emotion in problem and social drinkers
No full textAttentional bias (AB) for alcohol-related stimuli has been consistently demonstrated in social and problem drinkers. The aims of this study were to: investigate whether AB for alcoholrelated stimuli could be described as a slow effect as well as a fast effect; how these effects relate to drinking behaviour; and the influence of the experimental procedure on priming effects. Two experiments were designed. In experiment 1, problem drinkers in treatment at a community alcohol service (N¼62) and a group of social drinking controls (N¼60) were assessed using the modified Stroop task with alcohol, negative emotion and neutral words.
Drinking patterns were also recorded on the Khavari Alcohol Test. In experiment 2, social drinking controls (N¼40) completed the same procedure but were blinded to the study’s aims. In experiment 1, both groups demonstrated slower response times to alcohol-related than neutral stimuli in both fast and slow processes. Difference scores for alcohol compared to neutral words in the slow process were positively correlated with increases in drinking levels for both groups. In experiment 2, AB to alcohol-related stimuli disappeared when participants were unprimed. The findings highlight the importance of investigating the role of fast and slow processes in continued and problem drinking, alongside priming effects from the experimental procedure
Overview of tritium fast-fission yields
No full textTritium production rates are very important to the development of fast reactors because tritium may be produced at a greater rate in fast reactors than in light water reactors. This report focuses on tritium production and does not evaluate the transport and eventual release of the tritium in a fast reactor system. However, if an order-of-magnitude increase in fast fission yields for tritium is confirmed, fission will become the dominant production source of tritium in fast reactors
Fast ions in tokamaks and their collective measurement by collective Thomson scattering
No full textThe finite orbit widths of fusion products in tokamaks cause their distribution function to become anisotropic in velocity space. This anisotropy is closely related to the topology of fast ion orbit motion. For the study of orbit topology the equatorial surface is introduced which is a generalisation of the horizontal mid plane for tokamaks with broken top-bottom symmetry. By use of simple graphical methods the topology of guiding centre orbits are obtained and displayed by parameters characterising the particles at their intersections with this surface. On the basis of the results of the orbit topology study the anisotropic features of the distribution of fusion born a-particles are examined. For routine analysis of a-particles in JET plasmas a code is developed which integrates the Fokker-Planck equation describing classical slowdown of a-particles including finite orbit width effects. The code applies a new Green's function approach which considerably reduces the computational demands. The possibilities for the reconstruction of anisotropic distribution functions from CTS measurements are investigated. Results of tests and theoretical considerations for components in the CTS receiver are Outlined, and a procedure, developed for the calibration of the CTS detection system, is described. Examples of data measured by the CTS diagnostic are presented together with inferred fast ion distribution functions. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:D203786 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
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Preliminary Geologic Map of the North Half of the Union Pass Quadrangle, Mohave County, Arizona
No full textPreliminary Geologic Map of the North Half of the Union Pass Quadrangle, Mohave County, Arizona. Includes one map sheet with cross section at 1:24,000 map scale.On 1/17/2014, F.L. Hillemeyer's name was removed from the author list per his request. (The request was forwarded to AZGS by J.E. Faulds.)Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]
Superconducting Qubits and Quantum Resonators
No full textSuperconducting qubits are fabricated "loss-free" electrical circuits on a chip with size features of tens of nanometers. If cooled to cryogenic temperatures below -273 °C they behave as quantum elements, similar to atoms and molecules. Such a qubit can be manipulated by fast-oscillating magnetic fields and its resulting quantum state can be measured using a proper magnetic detector. These qubits could be the basic elements for a quantum processor. To that order, multiple qubits have to controllably interact, and to that purpose very high quality resonators are fabricated on the same chip. Effectively the interaction results from the phase-coherent exchange of a single photon between qubit and resonator. In this way it is highly analogous to the so-called cavity QED in atomic physics where single atoms couple to a single trapped photon, all inside a cavity resonator. In this thesis, a superconducting flux qubit has been coupled to an LC resonator and coherent exchange of a single photon between qubit and resonator has been achieved. A striking option in these superconducting circuits, not attainable in "common" atomic cavity-QED, is that the interaction between qubit and photon can be made very large, up to the limit that one no longer can talk about the qubit and resonator as such. This limit requires a fully different description and it leads to novel effects, e.g. in the energy spectrum of the qubit-resonator composite. The Bloch-Siegert spectral shift is experimentally demonstrated in this thesis. As a small but critical technical aside a new type of control line filter has been developed, which allows strong suppression of excess electrical noise that forms a threat for qubit coherence. Having two modes of operation, it shorts all low-frequency noise if control is idle while being transparent if control is active, where short or open is determined by the control line signal level itself.Quantum Transport GroupApplied Science
Building and Defining Behavioral Economics
No full textContains fulltext :
95156.pdf (Publisher’s version ) (Closed access)George Loewenstein, a prominent behavioral economist, recalls thatIn 1994, when Thaler, Camerer, Rabin, Prelec and I spent the year at the Center for Advanced Study in the Behavioral Sciences, we had a meeting to make a kind of final decision about what to call what we were doing. Remarkably, at that time, the name behavioral economics was not yet well established. I actually advocated “psychological economics,” and Thaler was strong on behavioral economics. I'm kind of glad that he prevailed; I think it's a better, catchier, label, although it creates confusion due to association with Behaviorism. (G. Loewenstein, personal email to author, June 16, 2008
The IPHAS catalogue of H alpha emission-line sources in the northern Galactic plane
No full textWe present a catalogue of point-source H alpha emission-line objects selected from the INT/WFC Photometric Ha Survey (IPHAS) of the northern Galactic plane. The catalogue covers the magnitude range 13 <= r' <= 19.5 and includes Northern hemisphere sources in the Galactic latitude range -5 degrees < b < 5 degrees. It is derived from similar to 1500 deg(2) worth of imaging data, which represents 80 per cent of the final IPHAS survey area. The electronic version of the catalogue will be updated once the full survey data become available. In total, the present catalogue contains 4853 point sources that exhibit strong photometric evidence for Ha emission. We have so far analysed spectra for similar to 300 of these sources, confirming more than 95 per cent of them as genuine emission-line stars. A wide range of stellar populations are represented in the catalogue, including early-type emission-line stars, active late-type stars, interacting binaries, young stellar objects and compact nebulae.
The spatial distribution of catalogue objects shows overdensities near sites of recent or current star formation, as well as possible evidence for the warp of the Galactic plane. Photometrically, the incidence of Ha emission is bimodally distributed in (r' - i'). The blue peak is made up mostly of early-type emission-line stars, whereas the red peak may signal an increasing contribution from other objects, such as young/active low-mass stars. We have cross-matched our H alpha-excess catalogue against the emission-line star catalogue of Kohoutek & Wehmeyer, as well as against sources in SIMBAD. We find that fewer than 10 per cent of our sources can be matched to known objects of any type. Thus IPHAS is uncovering an order of magnitude more faint (r' > 13) emission-line objects than were previously known in the Milky Way
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