Simultaneous Integer Values of Pairs of Quadratic Forms

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

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

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

Burgess bounds for short mixed character sums

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

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

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

Amino acids in a Fischer Tropsch type synthesis

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

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

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

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

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

Thurstonian Scaling of Compositional Questionnaire Data

To prevent response biases, personality questionnaires may use comparative response formats. These include forced choice, where respondents choose among a number of items, and quantitative comparisons, where respondents indicate the extent to which items are preferred to each other. The present article extends Thurstonian modeling of binary choice data (Brown & Maydeu-Olivares, 2011a) to “proportion-of-total” (compositional) formats. Following Aitchison (1982), compositional item data are transformed into log-ratios, conceptualized as differences of latent item utilities. The mean and covariance structure of the log-ratios is modelled using Confirmatory Factor Analysis (CFA), where the item utilities are first-order factors, and personal attributes measured by a questionnaire are second-order factors. A simulation study with two sample sizes, N=300 and N=1000, shows that the method provides very good recovery of true parameters and near-nominal rejection rates. The approach is illustrated with empirical data from N=317 students, comparing model parameters obtained with compositional and Likert scale versions of a Big Five measure. The results show that the proposed model successfully captures the latent structures and person scores on the measured traits