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AN EVALUATION OF THE SOCIOECONOMIC BACKGROUND OF OPTOMETRISTS IN NEW YORK STATE WAS MADE AND WAS RELATED TO DEVELOPED ATTITUDES ON COMMERCIALISM AND PROFESSIONALISM. THE STUDY WAS MADE TO DEVELOP A SOCIAL INDEX OF PROFESSIONALISM, TO DEVELOP AN UNDERSTANDING OF THE SOCIAL BACKGROUNDS THAT PRODUCE PRACTITIONERS WITH THE HIGHEST PRINCIPLES OF SOCIAL ETHICS, AND TO PROVIDE DATA FOR FURTHER RESEARCH IN THE AREA OF STUDENT SELECTION AND STUDENT EDUCATIONAL ACCULTURATION. OVER 55 PERCENT OF THE 1,640 OPTOMETRISTS PRACTICING IN THE STATE OF NEW YORK RESPONDED TO A MAILED QUESTIONNAIRE. A FACTOR ANALYSIS WAS MADE OF THE DATA GATHERED. FOR THE 83 INDEPENDENT VARIABLES, 12 FACTORS WERE IDENTIFIED, AND FOUR DEPENDENT FACTORS WERE DETERMINED FOR THE 60 DEPENDENT VARIABLES. RESULTS OF THE STUDY SHOWED THAT THE MOST SIGNIFICANT STATISTICAL FACTOR IN DEVELOPING AN UNDERSTANDING OF THE SOCIAL BACKGROUND THAT PRODUCES HIGH PRINCIPLES OF PROFESSIONAL ETHNICS WAS MEMBERSHIP IN THE NEW YORK OPTOMETRIC ASSOCIATION. THE AUTHOR CONCLUDED THAT MEMBERSHIP IN THAT ORGANIZATION TENDS TO FOSTER RELATIONSHIPS AND IDEALS THAT ARE CONSISTENT WITH A HIGHER LEVEL OF PROFESSIONALISM. (AL)

A terahertz metamaterial consisting of radiative slot antennas and subradiant complementary split-ring resonators exhibits plasmon induced opacity in a narrow spectral range due to the destructive interference between the bright and dark modes of the coupled oscillators. Femtosecond optical excitations instantly quench the mode coupling and plasmon oscillations, injecting photocarriers into the metamaterial. The plasmon resonances in the coupled metamaterial are transiently restored by intense terahertz pulses. The strong terahertz fields induce intervalley scattering and interband tunneling of the photocarries, and achieve significant reduction of the photocarrier mobility. The ultrafast dynamics of the nonlinear THz interactions reveals intricate interplay between photocarriers and plasmon oscillations. The high-field THz control of the plasmon oscillations implies potential applications to ultrahigh-speed plasmonics., 5 pages, 4 figures

Strong THz pulses instantly restore the sharp resonance of coupled plasmonic oscillators quenched by photoexcitation. The THz control of plasmon induced opacity is applicable to sensitive sensing and ultrafast switching in plasmonic devices.

We demonstrate that free-standing multi-walled carbon nanotubes exhibit extraordinary nonlinear terahertz responses upon optical excitation. Terahertz transmission of the photoexcited nanotubes rises in a narrow range of intermediate intensity with increasing intensity, while falling in the regime of low and high intensities. A theoretical analysis shows that the nanotube conductivity drops sharply in the region of intermediate intensity and soars elsewhere. Field-effect mobility and field-induced carrier multiplications are considered to be competing processes governing the rise and fall of the conductivity.

Objective: The study aimed to investigate the prevalence of cannabis use among undergraduate medical students of the University of the Free State (UFS), and the extent of their knowledge about the substance.Method: This cross-sectional study included five year groups of undergraduate medical students. A self-administered, anonymous questionnaire was used.Results: Of the 643 medical students, 541 (84.1%) completed the questionnaire. In total, 161 (30.9%) students reported that they had ever used cannabis. The percentage of males who had ever usedcannabis was twice that of females (relative risk 2.04; 95% CI 1.56; 2.67). Of the cannabis users, less than 12% used it monthly or more often. A fifth (19.5%) of all students stated that they did not know the side effects of cannabis use. Nearly half (45.4%) indicated that they could not name any medicinal (medical) uses. The median knowledge score of students who used cannabis tended to be higher than that of students who did not use cannabis; this was statistically significant only in the third-year group.Conclusions: Medical students generally have a low level of knowledge about cannabis. The reported lifetime prevalence and pattern of cannabis use are similar to those reported in other South African studies published over the past 35 years.

As a basis for providing meaningful job opportunities for the disadvantaged in health occupations, this study has investigated the current number, duties, and education and training of ancillary optometric personnel and the projected need for such employees. The study further describes the type of formal training program required to meet the increased public demand for quality of vision care and postulates career ladders for technical occupations in optometry. A stratified sample of the Nation's practicing optometrists was surveyed by mailed questionnaires. Questions were designed to determine the present and potential utilization of ancillary optometric personnel and to reveal the relation of specific job tasks to requisite levels of education and training and capacity for independent action. This information, in turn, has permitted the grouping of job tasks into various job descriptions. (NTIS)

Photocarrier injection by a femtosecond laser excitation immediately turns off the plasmon resonance in nanoantenna-patterned GaAs, while a strong and short terahertz pulse instantly revives the antenna resonance. The terahertz induced transparency, hugely boosted by the field enhancement in the antennas via the plasmon resonance, exhibits extremely nonlinear effects. The strong terahertz fields drive intervalley scattering and interband tunneling of the photocarriers and consequently reduce the transient conductivity of the photoexcited GaAs leading to the revival of the antenna resonance. In the high-field regime, the transient conductivity rapidly decays in the first few tens of picoseconds after the photoexcitation, while the photocarriers, initially in the highly nonequilibrium state, cool down and reach equilibrium, yet the decay significantly slows down at longer pump delays when the carriers settle down near the bottom of the conduction band.