Three-dimensional half-plane diffraction: Exact solution and testing of uniform theories

The exact solution of the diffraction problem for a plane electromagnetic wave at oblique incidence on a perfectly conducting half-plane was obtained more than 30 years ago. Recent advances in the high-frequency diffraction theory enable us to present the final solution in much simpler and suggestive forms. This solution is next used to test two uniform theories of edge diffraction. We find that uniform asymptotic theory (UAT) developed by Ahluwalia et al. recovers the exact solution, whereas uniform geometrical theory of diffraction (UTD) developed by Kouyoumjian and Pathak does not. The error of UTD is discussed.     

Varietal Differentiation of Grape Juice Based on the Analysis of Near- and Mid-infrared Spectral Data

The aim of this study was to evaluate the usefulness of visible (VIS), near-infrared reflectance (NIR) and mid-infrared (MIR) spectroscopy combined with pattern recognition methods as tools to differentiate grape juice samples from commercial Australian Chardonnay (n = 121) and Riesling (n = 91) varieties. Principal component analysis (PCA), partial least squares discriminant analysis and linear discriminant analysis (LDA) were applied to classified grape juice samples according to variety based on both NIR and MIR spectra using full cross-validation (leave-one-out) as a validation method. Overall, LDA models correctly classify 86% and 80% of the grape juice samples according to variety using MIR and VIS-NIR, respectively. The results from this study demonstrated that spectral differences exist between the juice samples from different varietal origins and confirmed that the infrared (IR) spectrum contains information able to discriminate among samples. Furthermore, analysis and interpretation of the eigenvectors from the PCA models developed verified that the IR spectrum of the grape juice has enough information to allow the prediction of the variety. These results also suggested that IR spectroscopy coupled with pattern recognition methods holds the necessary information for a successful classification of juice samples of different varieties.     

Continuous ion exchange using magnetic shell resins. II. Dealkalisation—pilot plant study

From the results obtained in the treatment of a number of hard, alkaline feed waters in a pilot scale dealkalisation plant, it has been shown that the use of a magnetic carboxylic acid resin in a fluidised bed has definite advantages over conventional systems. Less resin is needed and simpler plants can handle the same throughput of raw water whilst maintaining the same quality of product. Plant operation is truely continuous without any complex valve system or pressurised vessels.     

Single Soybean Seed NMR Calibration for Oil Measurement Using Commercial Cooking Oils

Development of high oil soybeans would reduce the cost of soybean oil production for biodiesel or edible oil applications. An accurate determination of soybean seed oil concentration is essential especially when developing superior cultivars with increased seed oil content. The objective of this study was to develop an oil measurement method for single seeds using NMR spectrometry. An NMR spectrometer was calibrated using commercial cooking oil. Fifteen cultivars of known mean oil content were used to evaluate the calibration curves. The calibration curves developed had a correlation coefficient of 0.99. It was found that soybean and corn oil gave identical results over the calibrated interval.     

High-frequency diffraction of a line-source field by a half-plane: Solutions by ray techniques

The diffraction of an arbitrary cylindrical wave due to a line source and incident on a half-plane is treated by the uniform asymptotic theory of edge diffraction. For large wavenumberk, an asymptotic solution for the total field up to and including terms of orderk^{-3/2}relative to the incident field is derived. This solution is uniformly valid for all observation points, including points near the edge and the shadow boundaries. In particualr, two special cases are considered: A) the line source is located on the half-plane, and radiates anE-polarized wave and B) the line source is located in the aperture complementary to the half-plane and radiates anH-polarized wave. A companion paper will show that our asymptotic solution for Case A) is in complete agreement with the asymptotic expansion of the exact solution. For the same diffraction problem, asymptotic solutions obtained by the method of slope diffraction coefficients and the method of equivalent currents are also discussed. It is found that the latter solutions agree with the exact one only when i) the observation point is away from the edge and the shadow boundaries, and/or ii) the terms of orderk^{-3/2}in the field solution are ignored.     

Is bone turnover a determinant of bone mass in rheumatoid arthritis?

OBJECTIVE: The aim of this study was to measure ultrasound (US) densitometric parameters [Broadband Ultrasound Attenuation (BUA), Speed of Sound (SOS), and stiffness of the os calcis] in patients with inflammatory bowel disease (IBD) and to compare the results with those obtained with conventional x-ray absorptiometry (DXA) of the lumbar spine. METHODS: Twenty-two patients with Crohn's disease (13 with ileal and nine with ileocolonic disease), 11 patients with ulcerative colitis (eight with left-sided and three with pancolitis), and 18 healthy controls. US densitometry of the right heel and DXA of the lumbar spine were performed within the same day. RESULTS: Compared to controls, IBD patients had significantly lower values with both methods, US and DXA. Forty-nine percent of patients had a lumbar T score below -1. Calcaneal SOS and stiffness of these patients were significantly reduced (p < 0.03 and p < 0.05, respectively). Positive significant correlations were found between lumbar DXA and calcaneal US parameters. Lumbar bone density and calcaneal US stiffness correlated inversely with the lifetime prednisone intake (p < 0.03 andp < 0.05, respectively), but not with age or duration of disease. A cut-off level of 80 dB/MHz for calcaneal BUA predicted axial osteopenia correctly in 74%, but some underestimation of spinal BMD was observed, especially in female patients with Crohn's disease. CONCLUSION: US evaluation of the os calcis gives results similar to those of conventional DXA and therefore may be used for screening IBD patients for axial osteoporosis. Because US does not expose patients to radiation, repeated measurements are possible and may be used to assess short term variations and the effect of treatment of IBD-associated bone disease.     

Influence of short-term dietary measures on dioxin concentrations in human milk

Breast-feeding may expose infants to high levels of toxic chlorinated dioxins. To diminish intake of these lipophilic compounds by the baby, two diets were tested for their ability to reduce concentrations of dioxins in human milk. The diets were a low-fat/high- carbohydrate/low-dioxin diet. (about 20% of energy intake derived from fat) and a high fat /low-carbohydrate/low-dioxin diet. These diets were tested in 16 and 18 breast-feeding women, respectively. The test diets were followed for 5 consecutive days in the fourth week after delivery. Milk was sampled before and at the end of the dietary regimen, and dioxin concentrations and fatty acid concentrations were determined. Despite significant influences of these diets on the fatty acid profiles, no significant influence on the dioxin concentrations in breast milk could be found. We conclude that short-term dietary measures will not reduce dioxin concentration in human milk.     

Prevalence and severity of the dementia syndrome in homes for the aged and nursing homes. A study in elderly from a rural area near Zwolle

In the Netherlands both nursing homes and homes for the aged serve as a residence for demented elderly. Although these institutions differ considerably regarding financing and care facilities, specific functions of each institute concerning demented elderly have not been clearly defined. In order to know to what extent residential facilities serve demented elderly, the prevalence and severity of dementia among residents aged 65 and over was studied as part of a prevalence study among elderly people in a rural area of the Netherlands. The target population existed of all persons aged 65 and over who were registered in eight general practices. Patients who had to leave the practice on account of ill-health and were admitted to nursing homes were included in the study. In a two stage study the MMSE was applied as a screening instrument. Based on MMSE-score a non-proportional stratified random sample was drawn for the second, diagnostic stage, which existed of the CAMDEX. Prevalence estimates for DSM-III-R-dementia were 21% among residents of homes for the aged, 48% among residents of somatic wards of nursing homes and 100% among those admitted to psychogeriatric wards of nursing homes. Severity of dementia was highest among residents of psychogeriatric wards of nursing homes and lowest among those living in homes for the aged. Prevalence of dementia among residents of homes for the aged can be fully attributed to the age-distribution. The high frequency of dementia among residents of somatic nursing home wards can be explained in several ways: First, admission can be necessary due to a combination of dementia and somatic illness.(ABSTRACT TRUNCATED AT 250 WORDS)