Dimensions of internal versus external control.

Explored the tenability of the assumption that Rotter's Internal-External (I-E) scale measures a undimensional trait by factor analyzing the 23 I-E item responses given by 159 male and 157 female undergraduates. 2 factors were identified: a belief concerning felt mastery over the course of one's life, and a belief concerning the extent to which the individual citizen is deemed capable of exerting an impact on political institutions. It is suggested that predictions involving the I-E scale might be refined by separate considerations of the 2 factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Application of a single-frequency unstable cavity to a CW HF laser

Demonstrations of diffraction-limited performance from a CW diffusion-type HF chemical laser are reported. A novel type of edge-coupled nonconfocal unstable resonator consisting of a convex mirror and a diffraction grating is used. A new technique of coupling power out of an unstable resonator different from the edge coupling previously suggested by Siegman is also applied. This consists of coupling power out directly through the diffraction grating zero-order radiation. By this technique, a large fraction of the total power is concentrated within the diffraction-limited main lobe. Peak power levels of the order of 100 W have been achieved on a single line [P_{2}(5)] for flow conditions yielding approximately 1 kW in closed cavity measurements.     

Power and efficiency of a continuous HF chemical laser

Experimental measurements of laser power output and chemical efficiency are reported for a continuous HF chemical laser. In this device, arc-heated N2is mixed in a plenum with SF6to provide F atoms. The mixture is expanded to form a supersonic jet into which H2is diffused. Population inversion and lasing are due to H2+ F → HF(υ) + H,upsilon leq 3, DeltaH = -31.7 kcal. Power levels up to 1 kW have been obtained. The efficiency of conversion of chemical energy to laser power is 16 percent at low SF6flow rates and approximately 10 percent at peak power. For a fixed arc power, addition of O2into the plenum raises peak power by about 25 percent under present operating conditions and reduces sulphur deposition on mirror surfaces. The presence of HF and DF in the plenums of DF and HF lasers, respectively, did not appear to degrade laser performance. (HF and DF levels up to 10 percent of the local F concentration were studied.) However, the presence of HF and DF in the plenums of HF and DF lasers, respectively, did degrade laser output. For given flow conditions, peak net laser power was obtained when the optical cavity axis was about 2 cm downstream of the H2injection station. The net output power was reduced to zero when the cavity axis location was increased to 5 cm.     

Zero-power-gain measurements in CW HF(DF) laser by means of a fast scan technique

An improved technique for measuring zero power gain in a CW HF-DF chemical laser has been developed in which a CW HF(DF) single-line, frequency-stabilized TEM00mode probe laser is used. Through use of a flat rotating mirror and focusing elements, the streamwise distribution of zero-power gain was scanned at a rate of ∼1 mm/μs with a spatial resolution of ∼1 mm. The zero-power-gain profile was observed for two arc-driven chemical-laser nozzles with both HF and DF active species. The nozzles consisted of a 36-slit array with perforated tube H2injectors and a 55-slit array with uniform H2injection. Results are presented for the variation of zero power gain with axial distance, the magnitude and location of peak gain, and the gain cutoff location for a number of transitions. Peak gain values of 15 percent/cm and 5.5 percent/cm were measured with HF and DF active species, respectively, with the 55-slit nozzle array.     

Reverse-wave suppressor mirror effects on cw HF unstable ring laser performance

The effect of a reverse-wave suppressor (RWS) mirror on the performance of a multiline cw HF ring laser was measured and theoretically discussed. Forward-wave far-field brightness was found to be very sensitive to the tilt of a conventional RWS mirror, being reduced by a factor of 2 for a 200-microrad RWS tilt. An aberrated mirror was found to reduce this tilt sensitivity by nearly an order of magnitude. Also discussed is a possible mechanism whereby the tilt of the conventional RWS mirror reinforced a higher-order mode in the forward-wave output, yet the tilt of the aberrated mirror did not.     

Self-advocacy and self-esteem.

Explored the utility of treating self-esteem as an attitude that might be vulnerable to the same kinds of experimental manipulations usually directed at more traditional, less consequential attitudinal issues. Within an attitudinal advocacy paradigm, 109 undergraduates wrote 3 essays either about their personality attributes or about social propositions. Half the Ss writing on each of these topics were told to advocate a positive position (i.e., self-laudatory or proposition supporting) in their essays. The remaining Ss, although induced to advocate positive positions, were led to believe that they could elect to write negative (self-deprecatory or issue-opposing) essays. As anticipated, Ss who wrote the self-laudatory essays subsequently rated themselves more favorably than did Ss who wrote in support of social propositions. The latter Ss showed a corresponding advocacy effect with regard to the social proposition that they had espoused. The manipulation of perceived choice did not influence the magnitude of the advocacy effect. The results are regarded as encouraging with respect to the application of laboratory-derived attitude change procedures to issues of high personal relevance and clinical importance. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)