Parts outweigh the whole (word) in unconscious analysis of meaning.

In unconscious semantic priming, an unidentifiable visually masked word (the prime) facilitates semantic classification of a following visible related word (the target). Three experiments reported here provide evidence that masked primes are analyzed mainly at the level of word parts, not whole-word meaning. In Experiment 1, masked nonword primes composed of subword fragments of earlier-viewed targets functioned as effective evaluative primes. (For example, after repeated classification of the targets angel and warm, the nonword anrm acted as an evaluatively positive masked prime.) Experiment 2 showed that this part-word processing was potent enough to oppose analysis at the whole-word level. Thus, smile functioned as an evaluatively negative (!) masked prime after repeated classification of smut and bile. Experiment 3 found no priming when masked word primes contained no parts of earlier targets. These results suggest that robust unconscious priming (a) is driven by analysis of part-word information and (b) requires previous classification of visible targets that contain the fragments later serving as primes. Contrary to a widely held view, analysis of subliminal primes appears not to function at the level of analysis of complete words.

Three cognitive markers of unconscious semantic activation.

A "response window" technique is described and used to reliably demonstrate unconscious activation of meaning by subliminal (visually masked) words. Visually masked prime words were shown to influence judged meaning of following target words. This priming-effect marker was used to identify two additional markers of unconscious semantic activation: (i) the activation is very short-lived (the target word must occur within about 100 milliseconds of the subliminal prime); and (ii) unlike supraliminal prime-target pairs, a subliminal pair leaves no memory trace that can be observed in response to the next prime-target pair. Thus, unconscious semantic activation is shown to be a readily reproducible phenomenon but also very limited in the duration of its effect.

On the equality of stimulated Brillouin scattering reflectivity to conjugate reflectivity of a weak probe beam.

If a strong pump wave, with energy that is above threshold for stimulated Brillouin scattering, and a weak probe wave are incident into a nonlinear medium, then it has been shown by others that the reflectivity of the weak probe is equal to the reflectivity of the strong pump and that the probe is phase conjugated provided that the pump is phase conjugated. We present an analysis that predicts an exact equality of the reflectivities and identifies the parametric limitations.

Narrow optical bandpass filter via nearly degenerate four-wave mixing.

It is shown that a nearly degenerate four-wave mixing process is capable of yielding a real-time optical bandpass filter. The filter has a large field of view and is capable of providing an amplified bandpass. Moreover, the conjugate nature of the output field can be utilized to increase the signal-to-noise ratio of the device. For a 1-cm interaction length in a nondispersive medium, the optical bandpass at 5000 A can be varied from ~9 GHz down to the linewidth of the exciting laser.

Resonator theory for hollow waveguide lasers.

A numerical technique has been developed for analyzing the transverse modes of waveguide lasers with external mirrors. Propagation outside the guide is computed with the Fresnel-Kirchhoff diffraction integral and within the guide by decomposing the fields into the characteristic modes of the guide structure. The transverse modes of the entire waveguide-mirror system fall into a number of distinct classes: TE(0m), TM(0m), EH(1m), EH(2m), etc. For each class of modes, the, corresponding guide modes form a complete and orthogonal set and may be used as basis vectors to describe those modes. This reduces the mode analysis of the waveguide resonator to the diagonalization of a small (5 x 5 or 10 x 10) complex matrix. Guide losses, coupling losses, and mode shapes will be discussed for a number of interesting cases, with the Fresnel number of the waveguide ranging from 0.1 to 1.0 and with various values of mirror curvature and position. It will be shown that some vales of resonator parameters are particularly advantageous for achieving single mode operation.

The effect of administration of human growth hormone on the plasma growth hormone, cortisol, glucose, and free fatty acid response to insulin: evidence for growth hormone autoregulation in man.

The effect of administration of human growth hormone (HGH) (3 mg every 6 hr for 6 days) on the endogenous GH response to insulin-induced hypoglycemia at 8, 12, 24, and 48 hr posttreatment was studied in 11 healthy male adults. Free fatty acid, cortisol, and glucose responses pre- and posttreatment with HGH were evaluated concurrently. Control subjects received saline injections to evaluate relationship of GH responses to the periodicity of insulin tolerance tests. The data were compared for each subject pre- and posttreatment with HGH as well as by comparison of the results of the saline-treated group with those of the HGH-treated group. The mean maximal GH concentration in response to insulin-induced hypoglycemia for all the subjects (n = 16) was 31.1 +/-3.6 ng/ml (+/-SEM) on day 1 of the control period and 23.4 +/-3.1 (SEM) on day 2, not statistically significant.A significant decrease in the maximal peak GH response (n = 8) after insulin-induced hypoglycemia was observed at 8 and 12 hr after HGH administration was terminated with mean peak values for GH of 4.6 +/-1.3 ng/ml and 10.4 +/-1.9 ng/ml, respectively (P < 0.01). A progressive return to control values was noted between 12 and 24 hr. The GH responsiveness of the saline-treated group (n = 5) was unchanged from that observed during the control period. The fasting glucose values were unchanged in the GH-treated group from those of the control period or of the saline-treated controls. Insulin resistance was apparent at 8 hr posttreatment with HGH. No differences in FFA response after insulin-induced hypoglycemia were observed in GH-treated or saline-treated subjects. The rise in plasma cortisol after insulin-induced hypoglycemia was comparable in the GH-treated and saline-treated group. Diurnal variation in plasma cortisol was maintained during the period of GH suppression. These observations support the concept that GH can modulate its secretion by means of an auto-feedback mechanism.