THE DEVELOPMENT OF THE SHALE PLANER1

The development of the shale planer from the first machine built by J. M. Powell fourteen years ago to the latest type is traced. Examples of applications at various plants are cited. Actual operating cost data on some of the latest type machines are presented. The advantages of a shale planer over other gathering machinery are discussed.     

Phase noise in coherent analog AM-WIRNA optical links

Coherent analog amplitude modulated-wideband rectifier narrowband (AM-WIRNA) systems have been the focus of many recent studies because of their high performance and relative immunity to phase noise compared to angle modulated systems. Despite their natural advantages over angle modulated systems, AM-WIRNA receivers are still vulnerable to phase noise because of distortion of their phase broadened signals in a finite bandwidth system. We present the first numerical analysis of the effects of this distortion on the performance of AM-WIRNA systems. The analysis accurately models the power spectral density of the phase-to-intensity noise with a root-mean-square deviation from the averaged experimental noise spectrum of 1.2 dB and a maximum deviation of 3.8 dB in the modulation range of <2 GHz. The accuracy of the analysis is limited primarily by nonidealities in the AM-WIRNA receiver and the accuracy of the analytical intermediate frequency (IF) filter model. Optimal link designs are presented which minimize the impact of phase-to-distortion noise in AM-WIRNA systems. We present experimental data from AM-WIRNA links which use both external cavity and distributed feedback lasers for the signal and local oscillator sources. The numerical analysis predicts the link signal-to-noise ratio (SNR) for different signal laser powers to within 1.4 dB of experiment. We find that systems requiring high SNR such as phased array antennas and AM-CATV are significantly affected by this noise     

Bone density and fracture risk in men

We evaluated different definitions of osteoporosis in a population-based sample of 348 men (age 22-90 years) compared with 351 women (age 21-93 years). Thirty-six men (10%) and 46 women (13%) had a history of osteoporotic fracture (hip, spine, or distal forearm due to moderate trauma at >/= age 35). In logistic regression analysis, osteoporotic fracture risk was associated with bone mineral density (BMD) at all sites (neck, trochanter, total hip, lumbar spine, and total wrist) in both genders (p < 0.001) except spinal BMD in men. After adjusting for age, total hip BMD was the strongest predictor of fracture risk in women (odds ratio [OR] per 1 SD decline, 2.4; 95% confidence interval [CI], 1.6-3.7), while wrist BMD was best in men (OR, 1.5; 95% CI, 1.1-2.0). Among men but not women, bone mineral apparent density (BMAD) was a better predictor of fracture than BMD (wrist BMAD OR, 1.7; 95% CI, 1.3-2.3). Hip BMD/BMAD decreased linearly from age 20 years onward in both genders, while spinal BMD/BMAD declined after age 40 in women but not in men. In both genders, total wrist BMD/BMAD decreased after age 50. By World Health Organization criteria, the age-adjusted prevalence of osteoporosis at the hip, spine, or wrist was 35% among women >/=50 years of age. A similar approach (BMD > 2.5 SD below the young male mean) produced an osteoporosis prevalence rate in men >/=50 years of age of 19%. Thus, bone density predicts fracture risk in men as it does in women, and the prevalence of osteoporosis in men, using sex-specific normal values, is substantial. These observations indicate a need for better prevention and treatment strategies for men.     

The modelling of equilibrium data for the liquid-liquid extraction of metals : Part II. Models for the copper/LIX 64N and chromate/Aliquat 336 systems

The equilibrium data for two examples of metal extraction are considered. The copper/LIX 64N system is an important one in that category involving the solvent extraction of acid leach liquors. In the case of alkali leach liquors the chromate/Aliquat 336 system provides the example. The data for each of these systems have been tested against various models. For the copper/LIX 64N system it has been shown that a polynomial gives the best fit, a modified chemical model is however only slightly worse. In the case of the chromate/Aliquat 336 system the chemical model is better than the polynomial.Parameters are reported for the best fits to each of the models tested and a computer display of a copper/LIX 64N surface is given.     

Excess-noise and receiver sensitivity measurements of In0.53Ga0.47As/InP avalanche photodiodes

We report the results of excess-noise and normalised receiver sensitivity measurements for In0.53Ga0.47As/InP avalanche photodiodes for use in the ?=0.95 ?m to 1.65 ?m spectral region. The excess-noise measurements are consistent with a hole-to-electron ionisation rate ratio in InP of ~ 0.4. The receiver sensitivity, measured at 45 Mbit/s and 10?9 bit-error-rate, was ?53.2 dBm at a gain of 20 assuming unity quantum efficiency for the detector. This sensitivity is the highest reported at ?=1.3 ?m and represents an improvement over a PIN detector using the same amplifier.     

Peer acceptance and school-related variables in an integrated junior high school.

Interracial peer acceptance at the junior high school level was related to 9 predictor variables: grade point average (GPA), IQ, attendance, self-concept of academic ability, sex, race, age, years in the school, and classroom racial composition. 322 7th- and 8th-grade students from predominantly lower-middle-class backgrounds were administered modified Syracuse Scales of Human Relations, measuring academic and social acceptance. Analysis of variance results show that White Ss slightly preferred Whites for the satisfaction of their academic and social needs. However, with stepwise multiple regression analysis, race was not a significant predictor variable for academic or social acceptance by White Ss. GPA and sex were the most prominent predictors of acceptance. Black Ss accepted both Black peers and White peers equally for academic interaction but preferred Blacks for social interaction. Race was a significant predictor variable for academic and social acceptance by Black Ss. However, race was secondary to GPA and/or sex for academic acceptance by Black females and Black males. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Digital correlation for noise radar systems

A recently developed radar system using a c.w. microwave noise spectrum from an impatt oscillator as the transmitted signal has shown useful performance. The application of a digital correlator to measure, essentially in real time, the autocorrelation function of the noise spectrum and provide a radar display of targets at ranges of up to at least 1 km is now described.     

Ammonia transport by the urinary bladder of Bufo marinus

Among cyanobacteria, the heterocystous, N2-fixing Anabaena variabilis and the unicellular Anacystis nidulans have recently been shown to possess an NAD+-dependent, bidirectional hydrogenase. A 5.0 kb DNA segment of the A. nidulans genome is now identified to harbor the structural genes hoxUYH coding for three subunits of the bidirectional hydrogenase. The gene arrangement in A. nidulans and in A. variabilis is remarkably dissimilar. In A. nidulans, but not in A. variabilis, the four accessory genes hoxW, hypA, hypB and hypF could be identified downstream of hoxH. An insertional homozygous mutant in hoxH from A. nidulans was completely inactive in performing Na2S204-dependent H2 evolution but could utilize the gas with almost 50% of the activity of the wild type. These findings with the first defined hydrogenase mutant in any photosynthetic, 02-evolving microorganism indicate that the unicellular cyanobacterium A. nidulans possesses both an uptake and a bidirectional hydrogenase. The physiological role(s) of the two hydrogenases in unicellular non-N2-fixing cyanobacteria is not yet understood.     

The empirical investigation of Perspective-Based Reading

We consider reading techniques a fundamental means of achieving high quality software. Due to the lack of research in this area, we are experimenting with the application and comparison of various reading techniques. This paper deals with our experiences with a family of reading techniques known as Perspective-Based Reading (PBR), and its application to requirements documents. The goal of PBR is to provide operational scenarios where members of a review team read a document from a particular perspective, e.g., tester, developer, user. Our assumption is that the combination of different perspectives provides better coverage of the document, i.e., uncovers a wider range of defects, than the same number of readers using their usual technique.To test the effectiveness of PBR, we conducted a controlled experiment with professional software developers from the National Aeronautics and Space Administration/Goddard Space Flight Center (NASA/GSFC) Software Engineering Laboratory (SEL). The subjects read two types of documents, one generic in nature and the other from the NASA domain, using two reading techniques, a PBR technique and their usual technique. The results from these experiments, as well as the experimental design, are presented and analyzed. Teams applying PBR are shown to achieve significantly better coverage of documents than teams that do not apply PBR.We thoroughly discuss the threats to validity so that external replications can benefit from the lessons learned and improve the experimental design if the constraints are different from those posed by subjects borrowed from a development organization.