Narrow-band correction of the residual amplitude modulation in frequency-modulation spectroscopy

We have developed a narrow-band controller in the MHz range, based on a field-programmable gate array. It is used to control the probe beam intensity in frequency-modulated spectroscopy experiments with an acoustooptic modulator. The residual amplitude modulation at the modulation frequency (2.5 MHz) is reduced by 50 dB. The first-harmonic detection of the signals is operated in saturation spectroscopy of I/sub 2/ at 514.5 nm and 501.7 nm. A reduction of the background noise and a large increase in the signal-to-noise ratio are obtained.     

EEG spectral abnormalities and psychosis as predictors of cognitive and functional decline in probable Alzheimer's disease

We examined whether either psychotic features (e.g., delusions and hallucinations) or EEG abnormalities are associated with more rapid progression of Alzheimer's disease (AD). AD patients with psychosis have exhibited more EEG abnormalities than those without psychosis, and both abnormal EEG and psychosis have been noted to be predictors of functional and cognitive decline in AD. Ninety-five probable AD patients participating in a longitudinal study of dementia had an EEG and a semistructured psychiatric interview at baseline. Using EEG spectral analysis, we classified records as normal/abnormal based on the parasagittal mean frequency. Patients with abnormal EEGs were more functionally (e.g., Blessed Rating Scale for activities of daily living) and cognitively (e.g., Mini-Mental State) impaired than patients with normal EEG. AD patients with psychosis were only more functionally impaired than patients without psychosis. A two-factor analysis showed no interaction between abnormal EEG and psychosis. In addition, using a Cox proportional hazard model adjusted for age and education, the presence of an abnormal EEG or psychotic symptom at study entry was associated with higher risk of reaching severe cognitive and functional impairment during follow-up. Neither abnormal EEG nor the presence of psychosis predicted death. These results indicate that both abnormal EEG and psychosis are independent predictors of disease progression but not of physical survival.     

Performance of natural‐fiber–plastic composites under stress for outdoor applications: Effect of moisture,temperature, and ultraviolet light exposure

The effects of moisture, temperature, and ultraviolet (UV) light on performance of natural‐fiber–plastic composites (NFPC) were assessed. We conducted short‐term tests in the laboratory and long‐term tests under natural exposure and measured changes in mechanical properties and color in samples of the composite. Chemical changes of the composite's materials were measured by X‐ray photoelectron spectroscopy to elucidate the mechanisms of chemical transformations on the material surface. Relative humidity highly affected the modulus of rupture (MOR) and the modulus of elasticity (MOE), and had a greater effect than temperature and UV exposure on performance of the composite. The lightness of the composite was increased by the UV effect in the short‐ and the long‐term tests. The X‐ray photoelectron spectroscopy (XPS) analysis suggested that the composite was protected by the UV absorber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2570–2577, 2006     

Algorithm for cosine transform of Toeplitz matrices

An algorithm for calculating the 2D cosine transform of a Toeplitz matrix is presented. The algorithm is based on the application of 1D cosine transforms. More specifically, four 1D cosine transforms of size N are needed to obtain the transform of a Toeplitz matrix of size N×N. This is an improvement over previously published algorithms. The algorithm is also simple and regular     

Sensitivity analysis of simulations for magnetic particle inspection using the finite-element method

Magnetic particle inspection (MPI) is widely used for nondestructive evaluation in aerospace applications in which interpretation of inspection results is currently limited to empirical knowledge and experience-based approaches. Advances in computational magnetics, particularly the use of finite-element calculations, have enabled realistic numerical simulations of magnetic particle inspection to be undertaken with complicated geometries. In this paper, we report a sensitivity analysis using finite-element-method simulations of magnetic particle inspection for defects with various sizes and geometries. As a result, improved quantitative understanding of the MPI technique and factors that affects its sensitivity and reliability has been achieved. These results can be used to optimize conditions for conducting these inspections and should lead to improvement in analysis and interpretation of experimental results.     

Solubility of actinide surrogates in nuclear glasses

This paper discusses the results of a study of actinide surrogates in a nuclear borosilicate glass to understand the effect of processing conditions (temperature and oxidizing versus reducing conditions) on the solubility limits of these elements. The incorporation of cerium oxide, hafnium oxide, and neodymium oxide in this borosilicate glass was investigated. Cerium is a possible surrogate for tetravalent and trivalent actinides, hafnium for tetravalent actinides, and neodymium for trivalent actinides. The material homogeneity was studied by optical, scanning electron microscopy. Cerium L_III XANES spectroscopy showed that the Ce³⁺/Ce_total ratio increased from about 0.5 to 0.9 as the processing temperature increased from 1100 to 1400 °C. Cerium L_III XANES spectroscopy also confirmed that the increased Ce solubility in glasses melted under reducing conditions was due to complete reduction of all the cerium in the glass. The most significant results pointed out in the current study are that the solubility limits of the actinide surrogates increases with the processing temperature and that Ce³⁺ is shown to be more soluble than Ce⁴⁺ in this borosilicate glass.     

The role of mineralocorticoid receptors in hypothalamic-pituitary-adrenal axis regulation in humans

In rodents, two types of glucocorticoid receptors, the mineralocorticoid (MR; type I) and the glucocorticoid (type II) receptors, have been demonstrated to play a role in hypothalamic-pituitary-adrenal (HPA) axis regulation. Because MR shows a very high affinity for cortisol, it has been suggested that MR plays an important role in restraint of CRH and ACTH secretion during the nadir of the circadian rhythm. Although a number of studies have established the importance of MR in rodents, the functional role of MR in humans has not been determined. These studies evaluated whether spironolactone, an MR antagonist, had a detectable effect on HPA axis regulation in humans, and whether the effect was greatest during the evening, when plasma cortisol concentrations are in the MR range. Compared to the placebo day, after a single dose of spironolactone at either 0800 or 1600 h, there is a significant increase in plasma cortisol, which is preceded by a rise in ACTH and beta-endorphin. A significant effect of spironolactone on cortisol secretion was demonstrated with no differences between the morning and evening. Because the effect of spironolactone on cortisol was short lived, a second experiment was conducted using two doses of spironolactone, again sampling in the morning and evening. After two doses of spironolactone, plasma cortisol levels showed a significant and sustained spironolactone-induced elevation for the entire sampling period. However, neither plasma beta-endorphin nor ACTH was increased compared to levels on the placebo day. These data suggest that MR appear to play a clear role in HPA axis regulation during the time of the circadian peak as well as the trough. Furthermore, MR blockade may affect the sensitivity of the adrenal to ACTH.     

GaAs pseudodynamic latched logic for high performance processorcores

A novel GaAs logic family, pseudodynamic latched logic (PDLL), is presented in this paper. It is composed of a dynamic circuit where the logic is performed and a static latch whose function is to permanently refresh the stored data on a dynamic node. Because of this hybrid structure, PDLL takes advantage of both static and dynamic families and thus, permits implementation of very complex structures with good speed-area power tradeoff. Moreover, the inclusion of the latch permits this class of logic family to be highly efficient for pipelined systems working even at high temperature without loss of data due to leakage currents. Barrel-shifters, programmable logic arrays (PLA's), and carry lookahead adders (CLA's) were verified by simulations demonstrating its feasibility for the development of high-performance very large scale integration (VLSI) systems     

Noise margin enhancement in GaAs ROM's using current mode logic

Two different techniques that allow the implementation of embedded ROMs using a conventional GaAs MESFET technology are presented. The first approach is based on a novel circuit structure named low leakage current FET circuit (L2FC), which reduces significantly subthreshold currents. The second approach is based on pseudo current mode logic (PCML) which is by far the best choice in terms of noise margin levels. This characteristic is found to be the key factor when implementing GaAs ROM's because of its degradation as the number of word lines is increased. A 5-Kb ROM and a 2-Kb ROM were designed giving delays in the order of 2 ns and less than 1 ns, respectively. The results demonstrate the effectiveness of these techniques and their significance toward improving the noise margin     

Dyadic perfectionism as a predictor of relationship continuity and distress among college students.

This study examined the nature and impact of dyadic perfectionism over a 3-month interval within a sample of 116 college students who were currently involved in an intimate heterosexual relationship. Dyadic perfectionism scores were stable and correlated as expected with scores on concurrent measures of adult attachment orientations and relationship satisfaction. Logistic regression analyses revealed that, controlling for initial commitment status and adult attachment orientations, Time 1 dyadic perfectionism scores significantly and uniquely predicted relationship continuity 3 months later. Lastly, controlling for social desirability, relationship commitment status, and Time 1 adult attachment orientation scores, Time 1 dyadic perfectionism scores also uniquely predicted Time 2 relationship distress. Findings provide additional evidence that dyadic perfectionism is a risk factor for relationship dysfunction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)