Recently developed structural models of the global crude oil market imply that the surge in the real price of oil between mid 2003 and mid 2008 was driven by repeated positive shocks to the demand for all industrial commodities, reflecting unexpectedly high growth mainly in emerging Asia. We evaluate this proposition using an alternative data source and a different econometric methodology. Rather than inferring demand shocks from an econometric model, we utilize a direct measure of global demand shocks based on revisions of professional real gross domestic product (GDP) growth forecasts. We show that forecast surprises during 2003–2008 were associated primarily with unexpected growth in emerging economies (in conjunction with much smaller positive GDP‐weighted forecast surprises in the major industrialized economies), that markets were repeatedly surprised by the strength of this growth, that these surprises were associated with a hump‐shaped response of the real price of oil that reaches its peak after 12–16 months, and that news about global growth predict much of the surge in the real price of oil from mid 2003 until mid 2008 and much of its subsequent decline. Copyright © 2012 John Wiley & Sons, Ltd.

The history of a family of exothermally reactive solids is studied theoretically with the help of analytical and numerical calculations. The different members of this family of nonisothermal solids are obtained, by changing scales and values of parameters, from the basic model which describes a zero-order reaction of a semi-infinite slab of material subjected at its surface to heat transfer from a gas. For low initial temperatures of the solid, the heat transfer rate determines the ignition time while for high initial temperatures, this heating parameter is less important than the initial temperature, which controls the adiabatic ignition time. For the model used, the ignition time is generally quite sensitive to the duration of the external heating. Within the solid, it is found that the inner boundary of the region in which the chemical heat production is negligible moves inward along a diffusional type of path x ∝ t½ but that the point of maximum temperature, which develops after interruption of the external heating, follows a much different path. An analytical, approximate method of estimating minimum ignition time was tested by making comparison with numerical integrations and is probably accurate to 25 percent in the ignition time. The computational side of the theory presented here may be regarded as essentially complete for practical purposes until greater accuracy and detail are required by more critical applications than are now in prospect. Meaningful utilization of the computations in practical applications will not however be possible until reliable measurements have been made of certain of the parameters for the solid—namely, activation energy, frequency factor and thermal conductivity—and for the external heating— namely, gas temperature and heat transfer coefficient. In the course of the computations, many mathematical questions arose which are fundamental to the investigation of this and more realistic models of ignition but which remain to be answered.

The non-linear Boltzmann equation has been solved for shock waves in a gas of elastic spheres. The solutions were made possible by the use of Nordsieck's Monte Carlo method of evaluation of the collision integral in the equation. Accurate solutions were obtained by the same method for the whole range of upstream Mach numbers M^ from 1.1 to 10 even though the corresponding degree of departure from equilibrium varies by a factor greater than 1000. Many characteristics of the internal structure of the shock waves have been calcu lated from the solutions and compared with Navier-Stokes, Mott-Smith and Krook descriptions which, except for low Mach numbers, are not based upon the Boltz mann equation itself. Among our conclusions are the following: 1. The reciprocal shock thickness is in agreement with that of the 2 Mott-Smith shock (u-moment) from M^ of 2.5 to 8. The density profile is asymmetric with an upstream relaxation rate (measured as density change per mean free path) approximately twice as large as the downstream value for weak shocks and equal to the downstream value for strong shocks. 2. The temperature density relation is in agreement with that of the Navier-Stokes shocks for the lower Mach numbers in the range of 1"1 to 1.56. The Boltzmann reciprocal shock thickness is smaller than the Navier-Stokes value at this range of Mach number because the viscosity-temperature relation computed is not constant as predicted by the linearized theory. 2 3. The velocity moments of the distribution function are, like the Mott-Smith shock, approximately linear with respect to the number density; however, the deviations from linearity are statistically significant. The four functionals of the distribution function discussed show maxima within the shock. 4. The entropy is a good approximation to the Boltzmann function for all M^. The solutions obtained satisfy the Boltzmann theorem for all Mach numbers. The increase in total temperature within the shock is small, but the increase is significantly different from zero. 5. The ratio of total heat flux q to (associated with the longi tudinal degree of freedom) correlates well with local Mach number for all M^ in accord with a relation derived by Baganoff and Nathenson. The Chapman-Enskog linearized theory predicts that the ratio is constant. The (effective) transport coefficients are larger than the Chapman-Enskog equivalents by as much as a factor of three at the mid-shock position. 6. At M 1=4, and for 40% of velocity bins, the distribution function is different from the corresponding Mott-Smith value by more than three times the 90% confidence limit. The rms value of the percent difference, in distribu tion function is 15% for this Mach number. The halfwidth and several other characteristics of the function Jfdw^dvz differ from that of the Chapman-Enskog first iterate, and many of the deviations are in agreement with an experiment by Muntz and Harnett. 7. The ratio of the collision integral (found from our solution of the Boltzmann equation) to that calculated from Mott-Smit...

Consonant discriminability by normal-hearing listeners was studied for monosyllables processed using frequency lowering with either uniform (linear) or nonuniform (warped) compression of the frequency axis. The bandwidth of the compressed signal was either 2500 or 1250 Hz and five compression characteristics were studied, in addition to low-pass filtering, for each of the two bandwidths. Stimuli were 24 consonant-vowel syllables made up of 24 consonants and three vowels, recorded three times by each of two male and female speakers. A "roving-speaker, roving-vowel, roving-utterance," two-interval, forced-choiced procedure with feedback was employed. As expected, performance for the 2500-Hz bandwidth was superior to that for the 1250-Hz bandwidth. For each bandwidth, compression schemes which accomplished greater lowering of the high frequencies relative to the low frequencies resulted in the highest performance. Overall performance for the best frequency-lowering system studied, however, was roughly comparable to that obtained for low-pass filtering. Patterns of performance over articulatory features were different for frequency lowering and filtering. In general, lowering was superior to filtering for contrasts of fricative sounds but inferior for contrasts of nasals and semivowels.

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