Showing papers by "California State University, Long Beach published in 1987"

Analysis of the interaction of a laser pulse with a silicon wafer - Determination of bulk lifetime and surface recombination velocity

Abstract: The decay of excess minority carriers produced in a silicon wafer of thickness d by a laser pulse is analyzed. A comprehensive theory based on this analysis is presented for the determination of bulk lifetime Tau(b) and surface recombination velocity S. It is shown that, starting with an exponential spatial profile, the carrier profile assumes a spatially symmetrical form after approximately one time constant of the fundamental mode of decay. Expressions for the spatial average of the carrier density as a function of time are derived for three temporal laser pulse shapes: impulse, square, and Gaussian. Particular attention is paid to the time constants of the fundamental and higher modes of decay. The ratios of the time constants of the higher modes to the fundamental mode, as well as the time constant of the fundamental mode, are presented over wide ranges of values of S and d. For Sd less than about 40 sq cm/s, a two-wafer method is developed to determine Tau(b) and S; it is also shown that the requirement of d/Tau(b) greater than about 20S is sufficient to adequately guarantee that the asymptotic value of the instantaneous observed lifetime differs from the bulk lifetime by no more than 10 percent.

Energy, tiredness, and tension effects of a sugar snack versus moderate exercise.

Abstract: After either eating a candy bar or walking briskly for 10 min on 12 selected days, 18 volunteers made systematic self-ratings of their energy, tiredness, and tension feelings for a fixed 2-hr period each day in the context of their normal daily activities. The snacking or walking activity was randomly selected on each test day after completion of a pretest. Results indicated that walking was associated with higher self-rated energy and lower tension significantly more than was snacking. In the walk condition reliable increases in energy and decreases in tension were observed for 2 hr. The sugar snack condition was associated with significantly higher tension after 1 hr, and a pattern of initially increased energy and reduced tiredness, followed 1 hr later by increased tiredness and reduced energy. The results partially support a general conceptual hypothesis that sugar snacking is often motivated by a low-awareness attempt to raise energy. Additionally, the results clarify an apparent conflict between neurochemical research, which indicates that sugar ingestion increases the tendency to sleep, and popular nutrition theory, which indicates that it increases tension.

Freeze dried anterior cruciate ligament allografts Preliminary studies in a goat model

Abstract: One ACL in each of 11 mature goats was replaced with a freeze dried bone-ACL-bone allograft. One year fol lowing implantation the goats had their knees evaluated biomechanically and for microvascularity and histologic changes. The reconstructed knees had a significantly greater total AP laxity (3.8 ± 0.6 mm) (mean and SEM) than the controls (1.0 ± 0.1 mm). Differences in primary AP laxity were responsible for 81 % of the difference in total laxity, with only a 0.4 mm difference in secondary laxity. Neutral stiffness in the reconstructive knee was 17% of control. while stiffness at 30 newtons (N) of anterior force was approximately 50% of controls. Lig ament stiffness in the linear region for the ACL allograft was 35% of the control value of 686 N/mm. The maxi mum load of the allografts was 571 ± 45 N, or 25% of the contralateral ACL control strength (2301 ± 155 N). Five of the seven allografts failed at the femoral inser tion. Both elongation (83%) and energy (21 %) to max imum load were less for allograf...

Cruciate reconstruction using freeze dried anterior cruciate ligament allograft and a ligament augmentation device (LAD): An experimental study in a goat model

Abstract: One ACL in each of 11 mature goats was replaced with a freeze dried bone-ACL-bone allograft and a ligament augmentation device (LAD). The LAD was released from its tibial fixation at 3 months postoperation. Bio mechanical, microvascular, and histological changes were evaluated 1 year following implantation. The re constructed knees had a significantly greater total AP translation (3.1 ± 0.5 mm) (mean and SEM) than the contralateral controls (1.0 ± 0.1 mm). Differences in primary AP translation were responsible for 59% of the difference in total translation, with only a 0.6 mm differ ence in secondary translation. Neutral stiffness in the reconstructive knee was 22% of control, while stiffness at 30 N of anterior force was approximately 35% of controls. Ligament stiffness in the linear region for the ACL allograft/LAD was 53% of the control value of 691 N/mm. The maximum load of the allograft/LADs was 1,052 ± 145 N, or 43% of the contralateral ACL control strength (2,448 ± 144 N). Five of the six allograft...

Cross-Cultural Differences in the Elicitation of Sexual Jealousy

Abstract: This paper focuses on cross‐cultural differences in sexual jealousy. It is assumed that cultures differ (a) in the incidence of sexual jealousy, (b) in the range of acceptable strategies for coping with a jealousy situation, and (c) in the behavior evoking sexual jealousy. We addressed the last aspect. Subjects were 2,079 students from seven industrialized nations: Hungary, Ireland, Mexico, the Netherlands, the Soviet Union, the United States, and Yugoslavia. Results showed that in nearly all of these nations, kissing, flirting, and sexual involvement of one of the partners with an interloper evoked jealousy. On the other hand, dancing, hugging, and sexual fantasies led, on the average, to a neutral reaction in all nations surveyed. Nevertheless, there were striking cross‐national differences in the relative value attached to a particular behavior. Furthermore, there were cross‐cultural sex differences. In all seven nations, women became more upset when their partner kissed someone else, and men reacted r...

Toward a Social Psychology of Social Support

Abstract: An analysis of social psychological aspects of social support examined several stages of the interaction between provider and recipient. In the first stage, the provider may offer support, respond positively to requests for support, or decline requests for support, whereas the recipient may seek, accept, or reject support. In the second stage, after support is exchanged, attributions about its effect may occur for each member, which in turn affects the extent to which the support is continued and the nature of its effect. Attributional errors about the effect may occur, especially if factors other than support—such as external factors—alter the problem status. The final stage follows the resolution of the problem and may involve reciprocation of support when roles are reversed, although such reciprocity may not be a necessary condition for social support. Possible mechanisms for both positive as well as negative effects of support were postulated. Assessing the effects of support is complicated by factors...

Problem perception, optimism, and related states as a function of time of day (diurnal rhythm) and moderate exercise: Two arousal systems in interaction.

Abstract: Two experiments are described in which perceptions of personal problems, optimism, and associated feelings were studied as a function of time of day and moderate exercise (walking). Over multiweek periods, participants completed self-ratings at fixed times of day representing high and low periods of energetic arousal. While ratings on individual days varied, means across all rating days indicated that problems were perceived as more serious at mid-to late afternoon, a period of low energetic arousal, than they were at late morning and after the walk, periods of high energetic arousal. Separate analyses of rated high energy and low tension states, compared to their opposites, indicated that problems were perceived as least serious in the former states. Ratings of optimism and associated feelings were consistent with the problem ratings. Also discussed are theoretical implications regarding moods as predispositional variables, state-dependent memory, and research involving naturalistic settings and aggregated measurements.

Dynamic display of the temporomandibular joint meniscus by using "fast-scan" MR imaging.

Abstract: In order to display temporomandibular joint (TMJ) images as a dynamic or motion study, a protocol was developed to obtain MR images of the TMJ in multiple phases of opening by using the "fast-scanning" capabilities of the GE Signa MR scanner. To facilitate this procedure a prototype device was also developed to passively open the patient's mouth from resting (closed) to fully open in user-defined increments (minimum 1 mm). MR imaging (surface coil) was carried out at each successive station using the GRASS, pulse-sequence data base of the GE Signa system operating at 1.5 T. Image-acquisition parameters were optimized in studies of cadavers and volunteers to obtain the clearest delineation of the TMJ meniscus and to determine any potential tradeoffs between total imaging time per slice (image quality), patient tolerance, and other practical considerations. For viewing, the images were sequentially placed in the video memory of the operating console and displayed in a back-and-forth-closed cine loop or "movie" mode at variable (operator-selectable) speeds. The dynamic sequences in four individuals were compared with static open- and closed-mouth views obtained with routine pulse sequences. Any single image from the dynamic display lacked the high resolution of the routine static images because of technical limitations of the pulse-sequence data base. However, in the movie mode the pertinent joint structures (such as meniscus and condyle) were clearly delineated, as were several of the important muscles of mastication. The anterior motion (translation) of the meniscus during jaw opening is particularly evident and suggests great potential for functional evaluation. These results show the feasibility of dynamic TMJ imaging with MR. The added information of the cine display potentially complements the routine static images and may prove extremely valuable in the assessment of TMJ dysfunction.

Dual viscosity mixer

Abstract: A device for the mixing of two or more fluids is disclosed which comprises an elongated hollow tubular member which is constricted intermediate its ends with a mixing zone comprising (a) at least two cylindrical orifices whose axes are substantially parallel to the axis of the tubular member for carrying a first fluid and (b) a fluid entry port for discharging a second fluid substantially between said two cylindrical orifices. The device is particularly advantageous when used for the mixing of two fluids having widely disparate viscosities.

Epidemiology of depression and dysphoria in an elderly Hispanic population. Prevalence and correlates.

Abstract: Depression among older minority groups, including Hispanics, has not been well studied. Little is known of the true rates of depression, it correlates or how well it is treated. This research is part of a series examining health status of older Hispanics using the Comprehensive Assessment and Referral Evaluation (CARE). Seven hundred older Hispanics living in Los Angeles County were studied using an area-probability sampling method. The CARE items were regrouped to reflect Diagnostic and Statistical Manual III criteria for depression and dysphoria. More than 26% were found to have a major depression or dysphoria. These affective disorders were strongly correlated with physical health status. Without physical health complications, the rate was 5.5%. A number of socioeconomic, health behavior, and family variables were related to affective state. Treatment for affective disorder appeared to be very poor for this population.

Water content in human intervertebral discs. Part I. Measurement by magnetic resonance imaging.

Abstract: Tension-relaxation experiments were performed on human disc lamellae specimens. The water content was found to affect the viscoelastic behavior and a master relaxation curve was constructed from the experimental data. The water content of disc phantoms is measured by magnetic resonance imaging (MRI) techniques. MRI was used to compare the discs of patients of different ages. The possibility of obtaining cross-sectional water distribution in human intervertebral disc material using MRI techniques and its relation to the disc's mechanical properties was explored, with the goal of constructing a realistic mathematical model of the disc which takes into account the water content of the disc.

Dynamic soil–structure interaction of a single‐span bridge

Abstract: Experimental and analytical studies were conducted to determine dynamic soil–structure interaction characteristics of a single-span, prestressed-concrete bridge with monolithic abutments supported by spread footings. The experimental programme, consisting of harmonic forced vibration excitation of the bridge in the transverse and longitudinal directions, revealed the presence of four modes in the frequency band, 0 to 11 Hz, and the onset of a fifth mode at 14 Hz, the highest frequency attained during the tests. The fundamental mode at 4.7 Hz was the primary longitudinal bending mode of the deck and had a relatively low damping ratio (ζ1), that was approximately 0.025 of critical. The second and third modes at 6.4 Hz and 8.2 Hz were the primary twisting modes of the deck which involved substantial transverse rocking, transverse translation and torsion of the footings. As expected, the damping ratios associated with these two modes, ζ2 = 0.035 and ζ3 = 0.15, were directly related to the relative amounts of deck and footing motion. The fourth mode at 10.6 Hz was the second twisting mode of the deck and involved relatively little motion of the footings and abutment walls, which was consistent with the low damping, ζ4 = 0.02, observed in this mode. The response data at 14 Hz suggested that the fifth mode beyond this frequency was the second longitudinal bending mode of the deck involving longitudinal translation and bending of the abutment walls. A three-dimensional finite element model of the bridge, with Winkler springs attached to the footings and abutment walls to represent the soil–structure interaction, was able to reproduce the experimental data (natural frequencies, mode shapes and bridge response) reasonably well. Although the stiffnesses assigned to the Winkler springs were based largely on the application of a form of Rayleigh's principle to the experimental data, these stiffnesses were similar to theoretical foundation stiffnesses of the same size footings on a linearly elastic half space and theoretical lateral stiffnesses of a rigid retaining wall against a linearly elastic backfill.

Is released time an effective component of faculty development programs

Abstract: A review of the literature on released-time programs shows a trend away from uncritical acceptance. Emerging skepticism about released time from teaching or service stems from a lack of evidence supporting its usefulness and from the mixed messages it gives about the value of teaching. Four demonstrational experiments confirm that skepticism by showing that (1) verified assessments of normal work loads contradict faculty claims of being too busy for additional scholarship; (2) faculty given released time usually persist in old habits; (3) new faculty showed no obvious benefits of a typical released-time program; and (4) faculty in released-time programs verbalized real doubts about how to use extra time for meaningful scholarship. A fifth experiment suggests an alternative to traditional released-time programs: faculty who claimed too little time for regular scholarship learned to produce significant amounts of writing by finding time for brief, daily writing sessions.

Tributyltin retards regeneration and produces deformities of limbs in the fiddler crab, Uca pugilator.

Abstract: Treatment of fiddler crabs,Uca pugilator, with levels of tributyltin (TBT) as low as 0.5 μg/L during limb regeneration resulted in a retardation of the regenerative growth and a delay in ecdysis at the end of the regeneration process. Limbs regenerated in the presence of TBT showed a variety of deformities, primarily a curved appearance. This was particularly apparent in regenerated chelae, in which the dactyl curved away from, rather than towards, the pollex. The number of setae was reduced in limbs that regenerated in TBT, compared to those that regenerated in clean sea water. Those that regenerated in clean sea water had a reduced number of setae in comparison to intact limbs. The production of deformities in the regenerated limbs was the most sensitive response and is consistent with findings in other groups of organisms, in which TBT also produces morphological abnormalities.

Water content in human intervertebral discs. Part II. Viscoelastic behavior.

Abstract: Water content of intervertebral discs is a significant aspect of both viscoelastic behavior and age-related degenerative changes. Using water content as a dependent variable, stress-relaxation was measured using standardized anulus fibrosus specimens strained at various levels of strain. Synthesis of experimental data into a master relaxation curve allows prediction of specimen response over time intervals not readily accessible experimentally. A quantitative understanding of the role of water content may have important clinical application, since magnetic resonance imaging is a tool which should allow water content determination in vivo.

Territory quality and territorial behavior in two sympatric species of hummingbirds

Abstract: Changes in territorial behavior of blackchinned hummingbirds (Archilochus alexandri) in response to experimental changes in territory quality were investigated using artificial feeders and simultaneous, pair-wise observations of owners. Some of the responses of A. alexandri were similar to those documented by a previous study of the Anna's hummingbird (Calypte anna): A. alexandri defending rich territories spent more time on their territories, encountered a greater percentage of intruders, and chased more intruders than did A. alexandri defending poor territories. In contrast to C. anna, A. alexandri supplemented chases with energetically inexpensive threat vocalizations more extensively when territory quality was increased. This difference may be related to A. alexandri's more tenuous control of rich territories. When both species were observed on very poor territories, A. alexandri chased a greater percentage of intruders, consumed a greater proportion of available food, and obtained a greater net energy gain from their territories. When observed simultaneously on territories with ad lib food, both species defended highly exclusive territories but A. alexandri suffered higher intrusion pressure and spent more time and energy in defense. These interspecific differences in territorial behavior may facilitate sympatric coexistence of the two species through aggressive partitioning of flower patches according to productivity: the greater payoff received by C. anna on rich territories and A. alexandri on poor territories should favor a corresponding monopolization of rich areas by C. anna and poor areas by A. alexandri.

Retinopretectal and accessory optic projections of normal mice and the OKN-defective mutant mice beige, beige-J, and pearl.

Abstract: Retinal projections to the pretectal and terminal accessory optic nuclei were studied in normal wild-type mice and mutant mice with abnormal optokinetic nystagmus (OKN, Mangini, Vanable, Williams, and Pinto: J. Comp. Neurol. 241:191-209, '85). The mutants used were pearl, which exhibits an inverted OKN in response to stimulation of only the temporal retina, and beige and beige-J, which show inverted OKN in response to stimulation of only the temporal retina and, in addition, exhibit eye movements with a vertical component in response to horizontally moving, full-field stimuli. These projections were studied following intraocular injections of 3H-proline or horseradish peroxidase (HRP) with, respectively, light microscopic autoradiography or HRP histochemistry. In wild-type mice, strong contralateral retinal projections covered the entire nucleus of the optic tract, the anterior and posterior divisions of the olivary pretectal nucleus, and the posterior pretectal nucleus. Similar heavy contralateral projections were distributed over the dorsal and medial terminal nuclei of the accessory optic system. Also, terminals sparsely covered the entire neuropil of the contralateral lateral terminal nucleus in some but not all wild-type mice. The most prominent accessory optic input was to the medial terminal nucleus and was provided by the inferior fasciculus of the accessory optic tract. A typical mammalian superior fasciculus of the accessory optic system with anterior, middle, and posterior components was present. Ipsilateral label was found in anterior and posterior olivary pretectal nuclei in all of the wild-type animals, but was found inconsistently in the ipsilateral terminal accessory optic nuclei. The pattern of contralateral retinal projection to the nucleus of the optic tract and posterior pretectal nucleus in mutants was indistinguishable from that seen in the normal wild-type mice. However, retinal inputs to the ipsilateral anterior and posterior olivary pretectal nuclei were significantly reduced in pearl mutants and were exceedingly sparse in the beige and beige-J mutant mice, while the contralateral inputs to these nuclei were increased in a complementary fashion in the mutants. The labeling of the accessory optic input to the contralateral dorsal terminal nucleus appeared to be substantially reduced in all of the mutant mice. The size of the principal accessory optic fascicle, the inferior fasciculus, was significantly smaller in beige, beige-J, and pearl mice; this reduction was greater in the beige and beige-J than in the pearl mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Skin heat exchanger

Abstract: Avionics systems are cooled by circulating the heated air through an onboard closed loop system which includes a heat transfer envelope comprised of a liner and the fuselage of the flight vehicle. The liner keeps a constant, thermodynamically optimal passage height between the liner and the fuselage, and is contoured in order to maintain that optimal height between the liner and internal structural support members which abut the fuselage and pass through the heat transfer envelope. The liner is comprised of flexible interlocking liner sections, each of which is produced from the same mold using heat and flame resistant material and subsequently trimmed to precisely fit into its particular area. Each liner section has a convex ridge which fits over an internal structural support member to enclose the member within the heat exchange envelope. Each convex ridge has transverse flexible ribs which accept and removably grasp the support member, thereby removably attaching the liner section to the support member. Each liner section also has a lip which overlaps and presses down against the succeeding adjacent section to hold it firmly in place, while at the same time effecting a seal. This mode of installation requires no riveting or other mechanical fasteners, and provides for quick and easy removal to facilitate maintenance or repair requiring access to the interior surface of the fuselage.

Situational and Individual Determinants of Teachers' Reported Use of Behavior Alteration Techniques

Abstract: Tying together principles applicable to compliance-gaining from both interpersonal and instructional communication theory and research, this investigation focused on situational and individual difference determinants of teachers’ strategy selection in the classroom Specifically, this study required teachers to focus on student misbehavior scenarios that reflected the situational determinants of misbehavior type (active/passive) and intensity (moderate/severe) Results indicated that teachers’ compliance-gaining message selection was influenced substantially by misbehavior type, and to a lesser extent, misbehavior intensity Assessments of teachers’ and students’ gender confirmed stereotypic differences for male and female teachers’ reported technique use, but no student gender effect was obtained These findings are compared with those obtained with prospective teachers (Plax, Kearney, & Tucker, 1986) Results are discussed in terms of cognitive scheme development for classroom management

Characterization of interfacial phenomena occurring during exposure of a thin copper film to an aqueous suspension of an acidic polysaccharide

Abstract: A Fourier transform infrared spectrometer equipped with a cylindrical internal reflection element was used to sample the solid—liquid interface of a metallic copper film submerged in an aqueous acidic polysaccharide solution. The presence of a polysaccharide absorption band at 1050 cm−1 in a water-subtracted spectrum supported previous spectroscopic data indicating polymer accumulation at the surface of the film. Firm binding of the polysaccharide to the surface after a 17-day exposure period was demonstrated by the retention of the 1050-cm−1 absorption band in spectra obtained after gentle rinsing of the film surface with polymer-free water. The sampling technique also provided evidence which suggests that acidic polysaccharides, including the firmly bound exopolymers produced by adherent cells of a freshwater sediment bacterium, promoted deterioration of the copper film. Internal reflection Fourier transform infrared spectroscopy appeared to be a useful, nondestructive method to study the sorption of biomolecules to a solid metal surface submerged in an aqueous medium.

A new method for the analysis and design of the class E power amplifier taking into account the Q_L factor

Abstract: Most previous papers on class E power amplifier are based on an analysis method proposed by Raab in which it is assumed that the Q_L factor of the series-tuned circuit is high enough that the output current is essentially a sinusoid at the carrier frequency. In this paper, a new method for the analysis and design of a class E amplifier is presented and implemented for the case of the series-tuned, shunt-capacitor class E configuration, in which the assumption of infinite Q_L is eliminated. The amplifier performance equations are obtained by finding the steady-state initial conditions of the load-network state variables. The design requirements are then imposed on the resulting equations. This leads to a nonlinear system of design equations which is solved for the design values using numerical optimization methods. For values of Q_L less than 15, the differences between the design values obtained using this method and those given by Raab become gradually more significant. The performance curves given in this paper show clearly that the overall amplifier performance is strongly affected by Q_L . Therefore, this method of analysis and design is useful because it provides accurate design values which ensure optimum and safe performance for the class E amplifier even in cases of low Q_L , it provides quantitative criteria for the usual tradeoffs concerning Q_L , and it makes the amplifier performance more predictable.