Search

Despite many years of research into the determinants of labour-force participation there is still a large degree of ignorance as to the impact of national fluctuations upon local labour-market supply. In the context of the recent recession, the effects of fluctuations in national money-wage rates and unemployment are related to variations in regional labour supply. A tentative model is presented and problems of testing economic relationships over time are discussed. With the Canadian case as an example, the model is then analysed and the results discussed.

Alabama Power Company has an ongoing program to improve the voltage profile of the 115 kV transmission system. This program includes the installation of a large number of distribution line capacitors. Initially, the distribution line capacitors were installed in the traditional fashion as fixed installations. However, with the wide spread deployment of Distribution Automation, consideration was given to switch the distribution capacitor installations to dynamically meet the electric distribution system's reactive load requirements, while supporting the 115 kV transmission system. Since the beginning of the Distribution Automation project, the distribution line has been monitored on a per phase basis with the deployment of each Distribution Automation device. This deployment strategy clearly demonstrated the dynamics and independent operation of the individual phases in the distribution line. This paper describes the development of the switched capacitor controller for application on the electric distribution system at Alabama Power Company. The development and operation of the switching algorithm will be reviewed. The packaging solution includes running the switching algorithm in the polemounted Remote Terminal Unit to facilitate one enclosure on the pole. The switching of the capacitors on a per phase basis is reviewed with closing being performed on zero voltage crossing and opening being performed on zero current crossing to minimize the impact and disturbance on the electric distribution system. The switched capacitor banks are monitored and controlled by the distribution system operator using the Supervisory Control And Data Acquisition (SCADA) technology that has been installed for Distribution Automation. The effect and impact on power quality is briefly discussed.

To evaluate an all-volunteer syringe exchange program in San Francisco, Calif.Syringe exchange program records and 11 semiannual surveys administered during a 5.5-year period, using standard questionnaires. Interviews (N = 5644) were conducted with injection drug users recruited in two 21-day drug detoxification clinics and three street settings.Use of the syringe exchange program and self-reported data regarding sources of syringes, frequency of injection, initiation into drug injection, and frequency of syringe sharing.In spring 1992, 45% reported "usually" obtaining injection equipment from the syringe exchange, and 61% reported using the program within the past year. During the period from December 1986 through June 1992, the median reported frequency of injection declined from 1.9 injections per day to 0.7 injection per day, the mean age increased from 36 to 42 years, and the percentage of new initiates into injection drug use decreased from 3% to 1%. In logistic regression analysis (of fall 1991 through spring 1992 interviews; n = 752), we found six independent factors associated with syringe sharing. Protective from syringe sharing were use of the syringe exchange program, having received human immunodeficiency virus (HIV) testing and counseling, condom use, older age, and African-American race. Injection of cocaine was a predictor for syringe sharing. The strength of association between use of the syringe exchange program and not sharing syringes was greatest in injection drug users younger than the median age of 40 years.The syringe exchange program was rapidly adopted by injection drug users. Health interventions associated with not sharing needles included use of the syringe exchange program and voluntary, confidential HIV testing and counseling. Our data did not support the hypothesis that a syringe exchange program would stimulate increased drug abuse in terms of frequency of injection or recruitment of new and/or younger users.

Cumulative trauma disorders are frequently responsible for the development of occupational neuropathy. Predisposing factors in the workplace are identified, and ergonomic principles to minimize these risks are presented.

Whereas many economic theorists hold both time and space in abeyance so as to simplify their analytics, economic geographers are beginning to question the utility of these strategies. Three papers which propose alternative conceptions are reviewed, criticized, and compared. It is noted that all three papers place a great deal of emphasis on understanding spatial differentiation; as a process and as a theoretical category. However plausible these conceptions, it is also noted that theorising the role of time in urban and regional economic analysis is still in its infancy. Nevertheless, these papers provide a diverse and interesting beginning point for further research.

The time of onset of ischemic stroke was determined for 1,167 of 1,273 patients during the collection of data by four academic hospital centers between June 30, 1983, and June 30, 1986. More strokes occurred in awake patients from 10:00 AM to noon than during any other 2-hour interval. The incidence of stroke onset declined steadily during the remainder of the day and early evening. The onset of stroke is least likely to occur in the late evening, before midnight.

Despite many years of research into the determinants of labour-force participation there is still a large degree of ignorance as to the impact of national fluctuations upon local labour-market supply. In the context of the recent recession, the effects of fluctuations in national money-wage rates and unemployment are related to variations in regional labour supply. A tentative model is presented and problems of testing economic relationships over time are discussed. With the Canadian case as an example, the model is then analysed and the results discussed.

Employers have a variety of reasons for attempting to stabilize turnover in their labour force. For example, specific skill requirements, the added costs of training inherent in hiring new workers, and the absolute demand for labour may stimulate firms to minimize labour turnover. One way of reducing turnover is for the individual firm to raise its wage rates. However, depending upon the relative tightness of the local labour market (reflected in the rates of hiring and unemployment), this could result in widespread wage competition amongst employers and general increases in the aggregate local wage rate. The significance of quits, hires, and unemployment are explored, in an attempt to explain differential urban wage inflation in the United States. Emphasis is placed on Hicks's model of labour turnover which emphasizes the firm's management of its labour needs. This model is analysed in a time-series framework over the period 1970 - 1979; a decade of rapid inflation and general stagnation in the United States.

Migration is often thought to be a long-run phenomenon. However, it is shown here by means of labor-force migration estimates derived from the Continuous Work History Sample over the period 1958 - 1975, that US interstate migration is quite volatile over the short run with respect both to its adjustment to macroeconomic fluctuations and to its geographical structure. A hierarchical clustering routine is utilized to analyse yearly estimates of interstate gross in-migration and out-migration so as to identify the temporal stability and characteristics of the geographical patterns of migration. States enter the national migration linkage tree at different levels for different years, depending upon the level of short-run economic activity. It is also shown that when national economic conditions worsen, labor-supply adjustments are more localized and the degree of interstate interdependence is less than in times of economic boom. An Almon distributed-lags time series regression model is used to formally test the relationship between spatial interconnectivity (as represented by interstate migration flows) and national fluctuations.

A direct method of observing the wavelength versus time of modulated single-mode GaAlAs lasers is described. The method uses a grating spectrometer and an avalanche photodiode and achieves resolutions of 0.01 A and 1 ns. Although the laser consists of a multi-layer heterostructure, a simple cylindrical thermal model is in good agreement with the experimental results.

Local labor markets are characterized by rigidities in their patterns of adjustment to short-run fluctuations. With or without unions, fluctuations in employment, hours worked, and money wages are unlike the patterns predicted by conventional discrete-exchange labor-market theories. Moreover there are distinct geographical and industrial patterns in the observed rigidities. Neoclassical implicit contract theory has been vindicated. Or has it? Obvious empirical difficulties remain, especially with regard to predicting which adjustment variable has precedence. There are conceptual shortcomings as well, evidenced by ad hoc assumptions of cooperative wealth maximization. By integrating the underlying structure of inequality with the processes of production and exchange, principles of an alternative conceptualization of contract theory are sketched and their implications noted for a set of hypothetical local labor markets. Based upon these arguments a research agenda for analyzing the relational character of local labor markets is briefly outlined.

It has been shown theoretically that a charged particle can be bound in stable orbits about the axis of a circular wave guide by the fields of the TE01 mode at cut-off (Weibel, 1959). This result was verified experimentally. The apparatus consists of a 20-cm long section of a circular wave guide - properly terminated - into which is fed radio-frequency power from a magnetron at f = 9.29 kMc/s in 2 μsec pulses. A uniform TE01 field is excited over the entire 20-cm length of the guide. An electron beam which is injected axially at one end of the cavity diverges strongly due to coulomb repulsion if no radio-frequency power is applied. During the radio-frequency pulse, however, the beam is confined to the axis and 90 per cent of the current is collected by an axial probe of 0.3-cm diameter which is located at the other end of the guide. Between pulses when no radio frequency is applied, no measurable current reaches the probe. In its trajectory from the gun to the probe each electron spends about 170 radio-frequency periods in the focusing field.

THE chief difficulty in measuring X-ray quanta or intensities by chemical methods lies in the fact that the total changes effected by this radiation during a reasonable time interval are too small to readily lend themselves to ordinary analytical procedure. In fact, the minuteness of the changes involved, together with the necessary accuracy needed, precludes ordinary chemical methods from all practical considerations by any but expert analytical chemists. Here exists the chief difficulty in the practical application of Eder's solution (1, 2) or any other similar chemical method to dosage measurements. Yet, the need for some accurate, simple, and convenient method for periodically checking the performance of X-ray tubes and dosimeters still exists. Many organic compounds change color while exposed to X-rays. The presence or absence of color furnishes some of the most accurate indications known of the progress of many chemical reactions. Of course, many organic reactions occur without color changes, but it...