The photorefractive effect in directional coupler and Mach-ZehnderLiNbO3 optical modulators at a wavelength of 1.3 μm

Previous work has shown that at a wavelength of 1.3 μm and power levels on the order of a few milliwatts, directional coupler switches show negligible damage due to the photorefractive effect. The author's experiments at higher power levels (20 mW) show a significant reduction in performance for 1-cm-long directional coupler modulators with uniform electrodes. The reduction in modulation efficiency is in good agreement with a numerical simulation based on the coupled mode equations using index changes estimated from previous work. At similar power levels, Mach-Zehnder modulators showed little effect making them a good design for high power applications. Other electrode structures, such as the reverse Δβ type, might help alleviate the effect in directional couplers. Modulators operating at 1.55 μm should also show less susceptibility to the effect     

High-power superluminescent diodes

By inclining the active stripe of a planar AlGaAs double heterojunction structure by 5° with respect to the facets, reflection feedback has been eliminated and high-power superluminescent diodes emitting 28 mW with less than 5% spectral modulation have been obtained     

Psychological effects of military service in Vietnam: A meta-analysis.

To integrate research on the psychological status of Vietnam veterans, we conducted a meta-analysis of 67 studies appearing in the literature from 1972 through 1985. Mean effect size, representing the comparison between Vietnam veterans and others on a variety of mental health indicators, was a significant –0.53. There was a tendency for larger effect sizes in studies that appeared later, were published by researchers affiliated with the Veterans Administration, documented combat history, but did not incorporate a comparison group. Vietnam veterans were significantly different from both Vietnam-era veterans and nonveterans, with the pattern of differences indicating a "Vietnam effect." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of repeated baseline testing on cognitive-skill-training-induced increments in hypnotic susceptibility.

Subjects who pretested as low in hypnotic susceptibility either received or did not receive a second baseline susceptibility test. Half of the subjects in each baseline test condition were administered cognitive skill training to enhance susceptibility, and half were given no training. Trained subjects exhibited much higher scores than untrained subjects on the objective and subjective dimensions of two different susceptibility posttests. The number of baseline tests given to subjects did not significantly affect posttest responding. These findings support the notion that hypnotic susceptibility can be substantially modified. They argue against the idea that training-induced gains in susceptibility are an artifact of giving subjects only a single-baseline test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

BUBBLE COALESCENCE IN STAGNANT LIQUIDS

The coalescence behavior of bubbles in aqueous solutions is investigated, A sharp transition on coalescence frequency is observed with increasing solute concentration. The mechanism of coalescence appears to be very different for volatile and non-volatile solutes.     

Sodium depletion enhances salt palatability in rats.

Stereotyped fixed action patterns (FAPs) elicited in rats by oral infusions of taste solutions can be classified as either ingestive or aversive. They reflect the palatability of the taste and can be modified by learning and by the physiological state of the animal. The present 2 experiments, with 5 male Sprague-Dawley rats, demonstrated that when the physiological state of the S was altered by sodium depletion, the pattern of FAPs elicited by oral infusions of 0.5 M NaCl shifted from a mixture of ingestive and aversive components (while sodium replete) to exclusively ingestive ones (while sodium deplete). This shift in taste reactivity occurred the 1st time the Ss were made sodium deplete. A similar shift did not accompany infusions of 0.01 M HCl, a taste solution that also elicited mixed ingestive and aversive FAPs. This result suggests that the shift in response to NaCl was not due to a general change in ingestive bias or to a general taste deficit. On the basis of the change in FAPs, it is concluded that the palatability of highly concentrated salt solutions increases in sodium-deplete rats. Such a shift in salt palatability may be instrumental in directing the appetitive behavior of the animal. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple processes in the automatic encoding of frequency information.

Conducted 2 studies in which a total of 96 undergraduates were unexpectedly asked to make frequency judgments about words used as distractors during a series of short-term memory tests for digit sequences. Frequency estimates of repeated items were influenced by the interaction of the duration of each vocalization and the number of trials intervening between the 2 occurrences of an item. As the separation between the occurrences increased, the frequency estimates increased only when the items were vocalized for long durations. This same result was not found for mere recognition of items, which was influenced independently by the frequency of presentation and duration of rehearsal. These findings are consistent with a multiple-process hypothesis of frequency representations, according to which distinct frequency traces vary in strength. Results also indicate that distinct representations for repeated events are encoded spontaneously during incidental processing. (French abstract) (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Software fault tree analysis

With the increased use of software in safety critical systems, software safety has become an important factor in system quality. This paper describes a technique, software fault tree analysis, for the safety analysis of software. The technique interfaces with hardware fault tree analysis to allow the safety of the entire system to be maximized. Experience with the technique and its practicality are discussed.