166,233 research outputs found

    Simultaneous Integer Values of Pairs of Quadratic Forms

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    We prove that a pair of integral quadratic forms in 5 or more variables will simultaneously represent "almost all" pairs of integers that satisfy the necessary local conditions, provided that the forms satisfy a suitable nonsingularity condition. In particular such forms simultaneously attain prime values if the obvious local conditions hold. The proof uses the circle method, and in particular pioneers a two-dimensional version of a Kloosterman refinement.Comment: 63 page

    Burgess bounds for short mixed character sums

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    This paper proves nontrivial bounds for short mixed character sums by introducing estimates for Vinogradov's mean value theorem into a version of the Burgess method.Comment: 20 page

    Positive psychology and romantic scientism: Reply to comments on Brown, Sokal, & Friedman (2013)

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    This is a response to five comments [American Psychologist 69, 626-629 and 632-635 (2014)] on our article arXiv:1307.7006.Comment: PDF, 9 page

    Amino acids in a Fischer Tropsch type synthesis

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    One postulation is described for the presence of organic compounds in meteorites which states that they were formed during the condensation of the solar nebula. A viable laboratory simulation of these conditions can be modeled after the industrial Fischer Tropsch reaction, which is known to produce organic compounds called hydrocarbons. In this simulation, a mixture of carbon monoxide, hydrogen and ammonia is heated in the presence of iron meteorite. The reaction products for amino acids, a class of organic compounds important to life, were examined. A large number of these compounds is found in meteorites and other chemical evolution experiments, but only small quantities of a few amino acids were found in the present simulation work. These results are at odds with the existing literature in which many amino acids were reported

    Determination of two-stroke engine exhaust noise by the method of characteristics

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    A computational technique was developed for the method of characteristics solution of a one-dimensional flow in a duct as applied to the wave action in an engine exhaust system. By using the method, it was possible to compute the unsteady flow in both straight pipe and tuned expansion chamber exhaust systems as matched to the flow from the cylinder of a small two-stroke engine. The radiated exhaust noise was then determined by assuming monopole radiation from the tailpipe outlet. Very good agreement with experiment on an operation engine was achieved in the calculation of both the third octave radiated noise and the associated pressure cycles at several locations in the different exhaust systems. Of particular interest is the significance of nonlinear behavior which results in wave steepening and shock wave formation. The method computes the precise paths on the x-t plane of a finite number of C(sub +), C(sub -) and P characteristics, thereby obtaining high accuracy in determining the tailpipe outlet velocity and the radiated noise

    The persistence of wishful thinking: Response to "Updated thinking on positivity ratios"

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    This is a response to Barbara Fredrickson's comment [American Psychologist 68, 814-822 (2013)] on our article arXiv:1307.7006. We analyze critically the renewed claims made by Fredrickson (2013) concerning positivity ratios and "flourishing", and attempt to disentangle some conceptual confusions; we also address the alleged empirical evidence for nonlinear effects. We conclude that there is no evidence whatsoever for the existence of any "tipping points", and only weak evidence for the existence of any nonlinearity of any kind. Our original concern, that the application of advanced mathematical techniques in psychology and related disciplines may not always be appropriate, remains undiminished.Comment: LaTeX2e, 10 pages including 6 Postscript figure

    Ground winds for Kennedy Space Center, Florida (1978 version)

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    Ground level runway wind statistics are presented for the Kennedy Space Center, Florida area. Crosswind, headwind, tailwind, and headwind reversal percentage frequencies are given with respect to month and hour for the Kennedy Space Center Space Shuttle runway. This document supersedes NASA CR-128995 and should be used in place of it

    Evidence for an Io plasma torus influence on high-latitude Jovian radio emission

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    We report the discovery with the Ulysses unified radio and plasma wave (URAP) instrument of features in the Jovian hectometer (HOM) wavelength radio emission spectrum which recur with a period about 2–4% longer than the Jovian System III rotation period. We conclude that the auroral HOM emissions are periodically blocked from “view” by regions in the torus of higher than average density and that these regions rotate more slowly than System III and persist for considerable intervals of time. We have reexamined the Voyager planetary radio astronomy (PRA) data taken during the flybys in 1979 and have found similar features in the HOM spectrum. Contemporaneous observations by Brown (1994) show an [SII] emission line enhancement in the Io plasma torus that rotates more slowly than System III by the same amount as the HOM feature
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