Frequency locking of semiconductor laser using PSK modulated signal

A random PSK modulated signal generated with an optical waveguide phase modulator is used to obtain an error signal and lock the frequency of an AlGaAs semiconductor laser to the /sup 7/Rb D/sub 2/ line. The measured error signal is similar to that obtained with sinusoidal phase modulation under the same conditions. The technique could be applied to longer wavelength lasers and other types of laser that cannot be directly modulated such as fibre lasers.<>     

Use of demographic and clinical characteristics in predicting length of psychiatric hospital stay: A final evaluation.

The literature on patient demographic and clinical characteristics as predictors of length of psychiatric hospital stay suggests that investigators have been unsuccessful in producing a prediction model using this information to account for any substantial criterion variance. The present study maximized predictions of length of hospital stay by using a more powerful statistical procedure and an expanded number of predictor variables. Data were obtained on 877 patients who were discharged from psychiatric hospitals in 1980. Results show that despite these improvements, the resulting proportion of variance was moderate at best. It is concluded that increases in similar information are unlikely to improve predictions. The use of untapped variables (e.g., management philosophies and politically based information) is discussed. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Finite element elastic-plastic-creep analysis of two-dimensional continuum with temperature dependent material properties

A technique is presented for performing finite element elastic-plastic-creep analysis of two-dimensional continuum composed of material with temperature dependent elastic, plastic, and creep properties. The plastic analysis utilizes the Prandtl-Reuss flow equations assuming isotropic material properties and linear strain-hardening. A power creep flow law formulated by Odquist is used to determine the steady state creep strain rate. The plastic and creep flow laws are employed to derive a ‘softened’ plastic-creep stress-strain matrix. These modified stress-strain relations are then used to formulate the element stiffness matrix in the usual manner. The differences in the elastic, plastic, and creep properties of the material due to the temperature change during the increment result in the formation of pseudo stresses, which in turn lead to load terms that appear on the right hand side of the equilibrium equations. The load terms resulting from these pseudo stresses not only keep the solution on the temperature dependent stress-strain curve of the material, but also correct for the elastic ‘overshoot’ that occurs when an element changes from an elastic to a plastic state. The effect of large displacements is included by the formulation of the geometric stiffness matrix for each element being used in the computer code. With this procedure it becomes economically feasible to perform elastic-plastic-creep stress analysis of two-dimensional continuum subjected to transient thermal and mechanical loadings. Several examples of both elastic-plastic and creep analyses are presented, and the finite element solutions are compared to either other theoretical solutions or experiment.     

A Similarity-Based Aspect-Graph Approach to 3D Object Recognition

This paper describes a view-based method for recognizing 3D objects from 2D images. We employ an aspect-graph structure, where the aspects are not based on the singularities of visual mapping but are instead formed using a notion of shape similarity between views. Specifically, the viewing sphere is endowed with a metric of dis-similarity for each pair of views and the problem of aspect generation is viewed as a segmentation of the viewing sphere into homogeneous regions. The viewing sphere is sampled at regular (5 degree) intervals and the similarity metric is used in an iterative procedure to combine views into aspects with a prototype representing each aspect. This is done in a region-growing regime which stands in contrast to the usual edge detection styles to computing the aspect graph. The aspect growth is constrained such that two aspects of an object remain distinct under the given similarity metric. Once the database of 3D objects is organized as a set of aspects, and prototypes for these aspects for each object, unknown views of database objects are compared with the prototypes and the results are ordered by similarity. We use two similarity metrics for shape, one based on curve matching and the other based on matching shock graphs, which for a database of 64 objects and unknown views of objects from the database give a recall rate of (90.3%, 74.2%, 59.7%) and (95.2%, 69.0%, 57.5%), respectively, for the top three matches; cumulative recall rate based on the top three matches is 98% and 100%, respectively. The result of indexing unknown views of objects not in the database also produce intuitive matches. We also develop a hierarchical indexing scheme to prune unlikely objects at an early stage to improve the efficiency of indexing, resulting in savings of 35% at the top level and of 55% at the next level, cumulatively.     

Characteristics of alpha-glucosidase production from recombinant Aspergillus oryzae by membrane-surface liquid culture in comparison with various cultivation methods

alpha-Glucosidase was produced using recombinant Aspergillus oryzae by membrane-surface liquid culture (MSLC), a method previously developed by the authors and the results compared with other methods, including shaking flask culture (SFC), agar-plate culture (APC), culture on urethane sponge supports (USC), and liquid surface culture (LSC) to determine possible reasons for the advantageous features of MSLC. When yeast extract was used as a nitrogen source, the amount of enzyme produced by MSLC was 5 or more times higher than those for SFC and LSC, but similar to that using APC. Enzyme production in USC was slightly lower than in MSLC and APC. Cell growth was similar irrespective of the cultivation method used. When NaNO3, a typical inorganic nitrogen source was used, enzyme production in all the cultures was lower than that using yeast extract. However, even using NaNO3, the amount of the enzyme produced by MSLC was 8 to 20 times higher than those by SFC, APC, USC, and LSC. Although cell growth using NaNO3 was similar to that for yeast extract in MSLC, it was markedly decreased in SFC, APC, and LSC. The reason for the difference in enzyme productivity for various cultivation methods using yeast extract and NaNO3 as a nitrogen source is discussed, on the basis of the experimental findings. The role of the oxygen transfer effect and gene expression levels in enzyme production were also examined.     

Blockade of NMDA receptors 2A subunit in the dorsal striatum impairs the learning of a complex motor skill.

Accumulating evidence proposes that the striatum, known to control voluntary movement, may also play a role in learning and memory. Striatum learning is thought to require long-lasting reorganization of striatal circuits and changes in the strength of synaptic connections during the memorization of a complex motor task. Whether the ionotropic glutamate receptor N-methyl-D-aspartate (NMDAR) contributes to the molecular mechanisms of these memory processes is still unclear. The aim of the present study was to investigate the role of striatal NMDAR and its subunit composition during the learning of the accelerating rotarod task in mice. To this end, we injected directly into the dorsal striatum of mice, via chronically implanted cannula, the NMDAR channel blocker MK-801 as well as the NR2A and NR2B subunit-selective antagonists NVP-AAM077 and Ro 25-6981, respectively, before rotarod training. There was no effect in the motor performances of mice treated with 1.0 μg/side of MK-801, 0.1 μg/side of NVP-AAM077, or 5 and 10 μg/side of Ro 25-6981. In contrast, injections of 2.5 and 5 μg/side of MK-801 or 0.5 and 1 μg/side of NVP-AAM077 impaired motor learning at Day 3 and 8. Interestingly, treatments with MK-801 and NVP-AAM077 did not alter the general motor capacities of mice as revealed by the stepping, wire suspension, and pole tests. Our study demonstrates that the NMDAR of the dorsal striatum contributes to motor learning, especially during the slow acquisition phase, and that NR2A subunits play a critical role in this process. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Usage patterns and misuse rates of automatic seat belts by system type

This study examined seat belt usage in North Carolina by drivers of 4,151 late model cars equipped with a variety of restraint system types. We measured usage by restraint type (automatic belt, air bag, manual belt), by make/model and by driver characteristics (age, sex, and race). Usage ranged from a high of 94.2% for motorized shoulder belts (but with only 28.6% lap belt usage in these cars) to 73.9% usage of manual lap/shoulder belts in cars equipped with air bags. Various types of misuse of the shoulder belt (e.g. excessive slack, detachment from the door, placement under the arm) were observed in nearly 6% of the sample.     

Global pollution monitoring of polybrominated diphenyl ethers using skipjack tuna as a bioindicator

To elucidate the global distribution of polybrominated diphenyl ethers (PBDEs), these chemicals were determined in the muscle of skipjack tuna (Katsuwonus pelamis) collected from offshore waters of various regions in the world (Japan, Taiwan, Philippines, Indonesia, Seychelles, and Brazil, and the Japan Sea, East China Sea, South China Sea, Indian Ocean, and North Pacific Ocean). PBDEs were detected in almost all the skipjack tuna collected from the locations surveyed (from < 0.1 to 53 ng/g of lipid), indicating widespread contamination by these compounds in the marine environment. Residue levels of PBDEs in these samples from the northern hemisphere seem to be higher than those from the southern hemisphere, which is plausibly due to larger usage of these compounds in the northern hemisphere. Higher concentrations of PBDEs were detected in the samples from waters around the East China Sea (up to 53 ng/g of lipid). Developing countries around the East China Sea are supposedly the "hot spots" releasing these chemicals into the marine environment. With regard to the composition of PBDE congeners, the percentage contribution by lower brominated congeners (BDE15, -28, and -47) showed an increasing trend with increasing latitude. On the other hand, higher brominated congeners (BDE153, -154, and -183) showed a reverse trend. These patterns suggest that lower brominated congeners of PBDEs (di-, tri-, and tetra-BDEs) were preferentially transported from pollution sources to northern colder regions through the atmosphere. PBDEs may have a high potency to cause global pollution like PCBs.     

Exploring the relative impact of biological sex and masculinity–femininity values on information technology use

Previous studies in an e-commerce context suggest that there are biological differences (i.e. whether one is a man or a woman) with respect to perceptions of websites. In other research, there is evidence that psychological gender (i.e. values such as masculinity or femininity) likewise influences website perceptions. It is the aim of the current investigation to explore the possibility that both biological sex and psychological gender influence user perceptions, and to examine the predictive power of each on our model. To test these assumptions, we use an augmented technology acceptance model (TAM). To maximise variance in our sample, participants are selected from two countries that are significantly different in masculinity–femininity. As expected, psychological gender better predicted trust and TAM than biological sex. Moreover, this study validates that the masculinity–femininity dimension as originally developed by Hofstede [1980. Culture’s Consequences: International Differences in Work-Related Values. Beverly Hills, CA: Sage] can be separated into two scales – one each for masculinity and femininity. The results suggest the need for additional research into the differentiation between psychological gender and sex.     

Vulnérabilité à la dépression chez les femmes victimes de violence conjugale: Contribution de la dépendance et l'autocritique.

The main purpose of this study is to evaluate the moderating effect of conjugal violence on the relationship between Dependency, Self-Criticism and depression. It investigates whether the contribution of personality to the severity of depressive symptoms diminishes as conjugal violence reported by women increases. Participants (N = 151) completed the Depressive Experiences Questionnaire, the Conflict Tactics Scales - II and two measures of depressive symptoms. The results of hierarchical hierarchical regression analyses, including quadratic interactions, indicate different patterns for each of the two personality dimensions. The main hypothesis is confirmed for Dependency: Dependency is related to the severity of depressive symptoms when violence is "moderate." However, the strength of this relationship diminishes as violence increases, the severity of the traumatic situation taking precedence over personal dispositions. On the other hand, results indicate that Self-Criticism adds up to the impact of conjugal violence on depressive symptoms. The discussion underlines the importance of integrating individual factors in the study of depression in women with a history of conjugal violence. It also underlines implications for the operationalisation of negative events likely to generate depressive affect in Dependent and Self-Critical individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)