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An overview of the binary collision impact theory of spectral line shapes has been given to provide a unified statistical mechanical approach to line-shape theory, laser theory, nonlinear optics, and transport phenomena in dilute gases. The computation of spectral line profiles corresponding to those obtained from ultra-high-resolution spectral line-shape measurements requires numerical ab initio calculation of scattering amplitudes directly from the underlying dynamics of collisions between radiatively active molecules and their perturbers. The Wigner distribution function-density matrix is utilized to describe the kinetic theory of spectral line shapes and to discuss the various collisional processes that contribute to the kernel of kinetic equations. The influence of features of the potential energy surface on spectral parameters is also discussed, and the importance of comparing experimental line profiles directly with numerically computed line shapes obtained from reliable interaction potentials is emphasized. This contrasts sharply with the universal practice of comparing experimental line widths and shifts using some average or approximate theoretical scattering cross- sections and it contrasts sharply with fitting experimental profiles to some convenient analytical line-shape model; hence the phrase 'a paradigm shift' in the title of this work. PACS Nos.: 32.70.Jz, 33.20.-t, 33.70.Gj, 34.50.-s. Nous avons presente une revue de la theorie du profile de raies spectrales suite a des collisions binaires, de facon a developper une approche unifiee de mecanique statistique pour la theorie du profile de raie, l'optique non lineaire, la theorie des lasers et les phenomenes de transport dans les gaz dilues. Le calcul du profil des raies spectrales qui correspondent a ces mecanismes exige un calcul ab initio des amplitudes de diffusion directement a partir de la dynamique des collisions entre des molecules a impact radiatif et les mecanismes perturbateurs. Nous couplons la fonction de distribution de Wigner et la matrice de densite pour decrire la theorie cinetique du profile de raie spectrale et discuter les differents mecanismes de collision qui contribuent au noyau des equations cinetiques. Nous analysons egalement l'influence des particularites de la surface d'energie sur les parametres spectraux et nous insistons sur l'importance de comparer les profiles experimentaux de raie directement avec les profiles de raie calcules a partir de potentiels fiables. Ceci contraste nettement avec la pratique universelle ou on compare les valeurs experimentales des largeurs et deplacements de raie en utilisant des sections efficaces approximatives quelconques, theoriques ou moyennes et contraste nettement avec l'ajustement des profiles de raie experimentaux a une forme analytique commode; d'ou l'expression << un changement de paradigm >> dans le titre. [Traduit par la Redaction], 1. Introduction The impact theory of spectral line shapes has been around for about a century, beginning with the classical theory of Lorentz [1], and was essentially completed with the [...]

An infrared laser spectrometer based on difference-frequency generation in LiI[O.sub.3] is described. The spectrometer has a frequency uncertainty of less than 1 MHz and a signal-to-noise ratio between 3000:1 and 10,000:1. These properties allow the spectrometer to be used for studies of the non-Lorentzian and non-Voigt character of absorption line shapes in atmospheric trace gases. OCIS codes: 300.1030, 300.6190, 300.6320, 300.6340, 300.6360, 300.6390.

The impact of the difference in public opinion on road pricing schemes in United Kingdom is examined.

We show that aperiodic coupled cavities may be designed to have a frequency-dependent complex reflectance that is anisotropic in phase (birefringent) and in amplitude (dichroic). The complex mean or average reflectivity may also be frequency dependent. As an illustration we show how such multicavity effects influence the stability of the polarization of light in quasi-isotropic lasers. Possible applications of the properties of aperiodic coupled cavities are suggested.

An intracavity polarimeter is described that is capable of measuring both weak birefringence and dichroism simultaneously. It uses, for the first time to our knowledge, polarization flips in a quasi-isotropic He-Ne laser. The laser operates at 3.39 micrometers. Calibration of the polarimeter is carried out by using the anisotropic properties of a tilted plate. As an illustration of the sensitivity, the diffractive anisotropy of an intracavity slit is measured.

Precise spectral line measurements of carbon monoxide in an operating pressure modulator cell permit independent determinations of the instantaneous gas temperature and pressure.

A model to assess flow and speed in aggregate road networks is examined in detail.

Studies the line broadening and shifting of the vibrational branch in pure HD. Shifting and broadening coefficients; Rates of state-to-state rotational energy transfer.

A digital divider circuit is used in a feedback circuit that is designed to stabilize laser-beam pointing. Key words: Digital divider, beam-pointing stability.

An overview of the binary collision impact theory of spectral line shapes has been given to provide a unified statistical mechanical approach to line-shape theory, laser theory, nonlinear optics, and transport phenomena in dilute gases. The computation of spectral line profiles corresponding to those obtained from ultra-high-resolution spectral line-shape measurements requires numerical ab initio calculation of scattering amplitudes directly from the underlying dynamics of collisions between radiatively active molecules and their perturbers. The Wigner distribution function-density matrix is utilized to describe the kinetic theory of spectral line shapes and to discuss the various collisional processes that contribute to the kernel of kinetic equations. The influence of features of the potential energy surface on spectral parameters is also discussed, and the importance of comparing experimental line profiles directly with numerically computed line shapes obtained from reliable interaction potentials is emphasized. This contrasts sharply with the universal practice of comparing experimental line widths and shifts using some average or approximate theoretical scattering cross-sections and it contrasts sharply with fitting experimental profiles to some convenient analytical line-shape model; hence the phrase 'a paradigm shift' in the title of this work. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the rapidly rising car ownership in Bangkok, the capital of Thailand, traffic congestion is increasing rapidly. TRAF‐NETSIM was selected for the detailed analysis of Bangkok conditions. However, most traffic signals in Bangkok are controlled by on‐site traffic police operating the controllers in manual mode. Hence the cycle time, length of stages and the sequence of stages are dependent on the minute by minute decisions of the traffic police. One of the constraints of TRAF‐NETSIM (and most other microsimulation models) is that the cycle time can have only one value for the whole network, and the sequence of stages must be in the same order throughout the simulation period. Therefore, the varying cycle times operated by the police had to be represented as a common value, and the sequence of stages had to be fixed. It was then necessary for simulation purposes to adjust the green times to maintain the observed capacities. The principles in Webster and Cobbe (Traffic signals, Technical Paper No. 56, Road Research Laboratory, H.M.S.O., London, England, 1966) were applied to achieve this. [ABSTRACT FROM PUBLISHER]

Presents information on a comparison between the experimental results and the polarization behavior predicted for quasi-isotropic single-frequency YAG laser. Information on the calculations which are done; Findings of the calculations.

Presents information on model for the polarization states of a single-frequency Nd...YAG laser. Details on the laser; Assumption that the laser cavity is linear and quasi-isotropic.

Using a difference frequency spectrometer we have measured the Q(2) to Q(38) 20[sup 0]0←01[sup 1]0,Σ←Π transitions of carbon dioxide at 296 K and pressures up to 15 kPa. These low pressure spectra were analyzed using both the Voigt model, and an empirical line shape that blends together a hard collision model and a speed dependent Lorentzian profile. The broadening coefficients were obtained with an accuracy of 1% or better. The low density or first order low pressure line mixing parameters were also determined. We have compared both our measured low pressure line-mixing parameters and the complete band spectrum at high pressures with those predicted by a relaxation matrix calculated from an EPG fitting law. Spectra at the highest pressures were recorded using both the difference frequency spectrometer and an FTIR spectrometer, the temperature for the latter experiments being 303 K. The vibrational band intensity and linear pressure shift of the branch as a whole were also measured. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports on the development of UK transport targets for CO2 emissions for 2050. Five key studies containing future carbon emissions scenarios for the UK were used to establish targets for overall reductions in emissions to achieve stabilisation at 550 and 450ppm of atmospheric CO2. Two approaches were used to consider the proportion of total emissions that would be attributable to transport in the future: 26% of total emissions as now and an increase to 41% of total emissions in line with forecasts. The overall targets and expected contributions from transport were used to derive target emissions for the transport sector to be achieved by 2050, which ranged from 8.2 to 25.8MtC. Even the weakest of these targets represents a considerable reduction from current emissions levels. [Copyright &y& Elsevier]