Coherently pulsed laser source

An electronically controllable apparatus is described which modulates a continuous wave laser beam so as to produce an output beam consisting of coherent pulses that are electronically controllable as to both pulse repetition rate and pulse width. The apparatus includes two acoustic devices positioned so that the laser beam passes through them in sequence, and apparatus for passing sound waves through the devices to frequency shift the laser radiation as well as to diffract it. Each acoustic device generates sound waves containing a group of frequencies which result in spaced pulses. The first acoustic device is countered by the second acoustic device to produce a collimated, coherently pulsed, laser beam

The model-independence of cosmic ray source determinations

The direct inversion method of Margolis is used to explore the dependence of Z less than or equal to 28 source abundance determinations on the choice of the pathlength distribution. The source abundances do not depend strongly on the form of the truncation used, although some truncation at the lower energies (compared to a leaky box) is necessary. The decrease of mean grammage with increasing energy is required by the observations. The effects of errors and he use of other secondary to primary ratios is discussed

Stark cell optoacoustic detection of constituent gases in sample

An optoacoustic detector for gas analysis is implemented with Stark effect cell modulation for switching a beam in and out of coincidence with a spectral line of a constituent gas in order to eliminate the heating effect of laser energy in the cell as a source of background noise. By using a multiline laser, and linearly sweeping the DC bias voltage while exciting the cell with a multiline laser, it is possible to obtain a spectrum from which to determine the combinations of excited constituents and determine their concentrations in parts per million

Least-squares analysis of clock frequency comparison data to deduce optimized frequency and frequency ratio values

A method is presented for analysing over-determined sets of clock frequency comparison data involving standards based on a number of different reference transitions. This least-squares adjustment procedure, which is based on the method used by CODATA to derive a self-consistent set of values for the fundamental physical constants, can be used to derive optimized values for the frequency ratios of all possible pairs of reference transitions. It is demonstrated to reproduce the frequency values recommended by the International Committee for Weights and Measures, when using the same input data used to derive those values. The effects of including more recently published data in the evaluation is discussed and the importance of accounting for correlations between the input data is emphasised.Comment: 12 pages, 4 figure

Correlation spectrometer having high resolution and multiplexing capability

A correlation spectrometer permanently incorporates a reference cell and an electro-optical phase modulator (EOPM) in the light path between a sample cell and a detector. The effect of the EOPM is such that its frequency modulates all of the monochromatic component of the incoherent radiation passing through it. The EOPM is adjusted so that when it is ON all of the energy in the monochromatic components is thrown into sidebands differing from the original frequencies by integral multiples of the modulation frequency with the total amount of energy absorbed from the original radiation remaining constant. When there is no coincidence between the constituents in the two cells, the detector's output is the same when the EOPM is ON and when it is OFF. However, when there is coincidence the detector's output changes when the EOPM is switched between its two states. The change in the detector's output is related to the quantity of the constituents in the sample cell

Sources of the ultraheavy cosmic rays

The suggestions that the source abundances of cosmic ray nuclei heavier then Fe differ significantly from Solar System abundances are not well supported by the data without assuming preferential acceleration. The Solar System abundances of Pb and Bi are split into r-, standard s-, and cyclic 8-process components; the apprarent deficiency of Pb seen in the HEAO-3 Heavy Nuclei Experiment data might indicate an absence of Pb from the recycling 8-process

The Efficiency of Collective Bargaining in Public Schools

This paper develops a bargaining model of wage and employment determination for the public sectror. The solution to the model generates structural wage and employment equations that are estimated using data from New York State teacher-school district collective bargaining agreements. An advantage of this approach is that the major collective bargaining models (monopoly union, right to manage, efficient contracting, and inefficient contracting) are nested in the structural equations based on flexible functional forms and these models can be empirically tested as restrictions on estimated model parameters. The empirical results suggest that the allocation of resources generated by collective bargaining in New York State public schools is, by and large, not Pareto efficient. Furthermore, it is possible to estimate separate measures of union bargaining power over wages and employment. Empirically, it appears that union bargaining power over wages is around 0.53, while bargaining power over employment is around 0.71. In addition, the paper demonstrates the importance of controlling for the nature of the collective agreement when measuring the level of public services that flow to a community in the presence of a unionized public sector work force. Nous proposons un modèle de négociations collectives sur les salaires et l'emploi dans le secteur public. La solution de ce modèle implique des équations structurelles de détermination des salaires et d'emploi qui sont estimées à partir de données provenant des conventions colléctives des écoles publiques de l'état de New York. Notre approche a l'avantage d'englober tous les modèles majeurs de la littérature sur les négociations collectives (syndicat monopole, droit à gérer, négociations efficaces et négociations inefficaces) et de relier chaque modèle à une restriction d'égalité sur un ou plusieurs paramètres estimés. Nos résultats suggèrent que l'allocation des ressources spécifiée dans les conventions collectives des enseignants de l'état de New York n'est, en générale, pas efficace. De plus, notre approche nous permet d'estimer le pouvoir de négociationsur les salaires et sur l'emploi séparément. Nous trouvons un pouvoir de négociation sur les salaires de 0.53, et sur l'emploi de 0.71. Finalement, nous démontrons l'importance de contrôler le caractère endogène des salaires lors de l'analyse des flux des services publics dans un marché syndicalisé.Collective Bargaining, Efficient Contracting, Public Sector Union, Education, Négociations collectives, contrats efficaces, syndicat du secteur public, éducation

Alfven wave scattering and the secondary to primary ratio

The cosmic ray abundances have traditionally been used to determine the elemental and isotopic nature of galactic ray sources and average measures of propagation conditions. Detailed studies of the physics of propagation are usually paired with relatively straightforward estimates of the secondary-to-primary (S/P) ratios. In the work reported here, calculations of elemental abundances are paired with a more careful treatment of the propagation process. It is shown that the physics of propagation does indeed leave specific traces of Galactic structure in cosmic ray abundances

Use of high-resolution measurements for the retrieval of temperature and gas-concentration profiles from outgoing infrared spectra in the presence of cirrus clouds

We explore ways in which high-spectral-resolution measurements can aid in the retrieval of atmospheric temperature and gas-concentration profiles from outgoing infrared spectra when optically thin cirrus clouds are present. Simulated outgoing spectra that contain cirrus are fitted with spectra that do not contain cirrus, and the residuals are examined. For those lines with weighting functions that peak near the same altitude as the thin cirrus, unique features are observed in the residuals. These unique features are highly sensitive to the resolution of the instrumental line shape. For thin cirrus these residual features are narrow (≤0.1 cm-1), so high spectral resolution is required for unambiguous observation. The magnitudes of these unique features are larger than the noise of modern instruments. The sensitivities of these features to cloud height and cloud optical depth are also discussed. Our sensitivity studies show that, when the errors in the estimation of temperature profiles are not large, the dominant contribution to the residuals is the misinterpretation of cirrus. An analysis that focuses on information content is also presented. An understanding of the magnitude of the effect and of its dependence on spectral resolution as well as on spectral region is important for retrieving spacecraft data and for the design of future infrared instruments for forecasting weather and monitoring greenhouse gases