Defect imaging with elastic waves in inhomogeneous-anisotropic materials with composite geometries.

Imaging of defects in composite structures plays an important role in non-destructive testing (NDT) with elastic waves, i.e., ultrasound. Traditionally the imaging of such defects is performed using the synthetic aperture focusing technique (SAFT) algorithm assuming homogeneous isotropic materials. However, if parts of the structure are inhomogeneous and/or anisotropic, this algorithm fail to produce correct results that are needed in order to asses the lifetime of the part under test. Here we present a modification of this algorithm which enables a correct imaging of defects in inhomogeneous and/or anisotropic composite structures, whence it is termed InASAFT. The InASAFT is based on the exact modelling of the structure in order to account for the true nature of the elastic wave propagation using travel time ray tracing techniques. The algorithm is validated upon several numerical and real life examples yielding satisfactory results for imaging of cracks. The modified algorithm suffers, though, from the same difficulties encountered in the SAFT algorithm, namely "ghost" images and eventual lack of clear focused images. However, these artifacts can be identified using a forward wave propagation analysis of the structure.

Calculation of high frequency ultrasonic signals for shear wave insonification in solid material.

The goal of the theoretical part is to simulate an automatic ultrasonic inspection with contact technique shear wave probes, where the high frequency signals are captured and used to perform a reconstruction based on the synthetic aperture focusing method "SAFT". Therefore the ultrasonic probe, the scanning path and the defects are parameters in a CAD model. The scattering behavior of the defect is calculated by the Kirchhoff approximation in its elastodynamic version. The result of the simulation--the high frequency data--and the result of the SAFT-reconstructions are compared with experimental results on a steel test block with side drilled and flat bottom holes. The model is validated by the experiment. One of the applications of the model is to identify multiple reflections.

Chromosomal anomalies in oligodendroglial tumors are correlated with clinical features.

BACKGROUND: Patients who have oligodendrogliomas (OD) that demonstrate loss of both 1p and 19q appear to have a better prognosis after they receive chemotherapy and radiotherapy compared with patients who have OD without these characteristics. It is unclear whether this improvement in outcome is due only to a better response to treatment. The authors investigated the correlation between genetic and clinical characteristics of OD in 33 patients who received chemotherapy with procarbazine, lomustine, and vincristine for recurrent disease after receiving radiotherapy. METHODS: The initial presentation, prior treatments, overall survival, and response to chemotherapy were assessed. The 1p and 19q status in OD lesions was determined with fluorescence in situ hybridization on paraffin embedded, archival material using locus specific probes. P53 mutations were assessed by polymerase chain reaction-single-strand conformation polymorphism analysis and immunohistochemistry for P53; the proliferation index was assessed with the MIB-1 antibody. RESULTS: Patients who had OD lesions with a combined loss of 1p and 19q typically presented with low-grade tumors that manifested with seizures of long-standing duration. In contrast, patients who had OD lesions without a combined loss of 1p and 19q usually presented with focal deficits that required immediate treatment. Both the response rate to chemotherapy and the time to disease progression after chemotherapy were significantly better in patients who had a combined loss of 1p and 19. Tumors with classic OD morphology more often had a combined loss of 1p and 19q, although the genotype was better at identifying patients with chemoresponsive tumors. P53 mutations were observed in three tumors, none of which had a combined loss of 1p and 19q. CONCLUSIONS: OD lesions with combined a loss of 1p and 19q have a more indolent nature compared with OD lesions that do not have these losses. Virtually all patients with these tumors present with low-grade tumors accompanied by seizures and remain stable for prolonged periods. Future trials must keep these tumor types apart.

Deep vein and isolated calf muscle vein thrombosis following long-haul flights: pilot study.

The risk of venous thromboembolism associated with long-haul flights is the subject of controversy. In a prospective, controlled study, we examined 160 passengers before and after return from a long-haul flight and 160 age-matched and sex-matched, non-travelling volunteers using venous compression ultrasound. Deep vein thrombosis was not observed in either group. Isolated calf muscle vein thrombosis (ICMVT) was present in 4/160 (2.5%) flight passengers and in 1/160 (0.6%) controls. All subjects with ICMVT were clinically asymptomatic, and ICMVT was located in the soleal muscle veins in all four subjects. Three of the four passengers with ICMVT had other risk factors for thrombosis.

Cetaben versus clofibrate: comparison of toxicity and peroxisome proliferation in rats.

Cetaben and clofibrate were each administered to groups of 6 rats (3 male and 3 female) by gavage at dosages of 50 mg/kg per day and 200 mg/kg per day for 2 weeks. Cetaben caused 1 death at 200 mg/kg per day and decreases in body weight gain and food consumption at 50 mg/kg per day or more. There were no effects on body weight or food consumption in the clofibrate-treated groups. At 200 mg/kg per day cetaben and clofibrate induced comparable increases in liver weight and in numbers of liver peroxisomes while cetaben caused increases in liver catalase activity as well.

High density lipoprotein utilization by dispersed rat luteal cells.

Utilization of lipoproteins by cells prepared by collagenase dispersion of ovaries of immature gonadotropin-primed rats was studied. Human and rat HDL increased basal progestin secretion and incorporation of [14C]oleate into cellular sterol esters 2-fold during a 2 h incubation, with maximal stimulation occurring at a lipoprotein sterol concentration of 125 micrograms/ml. This concentration of HDL cholesterol also increased progestin production by cells stimulated with dibutyryl cyclic AMP. Human LDL or cholesterol-rich lipid dispersions had little effect upon either progestin secretion or sterol esterification at similar sterol concentrations. However, addition of delipidated human HDL apolipoproteins to the cholesterol-rich lipid dispersions markedly enhanced progestin production. Incubation of the dispersed cells in the presence of 25 micro M ML-236B, which blocked cellular de novo sterol synthesis by over 90%, had no effect upon progestin secretion. Specific uptake of human 125I-labeled HDL by the dispersed cells was observed. Analysis fo 125I-labeled HDL uptake as a function of lipoprotein concentration indicated that the uptake process was saturated at HDL levels of 200-400 micrograms protein/ml. The amount of HDL specifically associated with the cells at saturating levels after 1 h of incubation was sufficient to account for the increased progestin synthesis and sterol ester storage observed during this time. During the incubations cell-specific degradation of the 125I-labeled HDL apolipoprotein appeared to be minimal. We conclude that lipoprotein-carried cholesterol is an important substrate for rat luteal cells and that these cells possess a specific mechanism for the uptake of HDL.

[Phospholipids in fatal strangulations (author's transl)]. / Zur Aussagekraft der Phospholipid-Konzentration in Sinus- und Herzblut Erhängter.

A comparison of phospholipid content of sera from heart blood and sinus blood from the brain with the rate of haemolysis in the blood samples, with age, sex, degree of arteriosclerosis and cause of death, showed a relationship with the cause of death in spite of wide dispersion of the single values. The remaining factors of the 145 unselected human cadavers, which were not putrefied, seemed to have no influence. Small amounts of haemolysis caused a decrease of phospholipid concentration whereas an extensive haemolysis clearly led to an increase. The results of 46 deaths by hanging confirmed the fundamental studies of Berg (1950, 1952), who demonstrated that an increased secretion of phospholipids during the strangulation process is to be interpreted as a vital phenomenon. Compression of cervical vessels resulted in statistically significant differences between phospholipid concentrations in serum of heart and sinus blood.

Hydrogen-oxidizing methane bacteria. II. Electron microscopy.

Comparison of the fine structure of the methanogenic organism from the culture known as Methanobacillus omelianskii with that of Methanobacterium formicicum revealed a great similarity. Both organisms exhibited a large number of intracytoplasmic membranous elements when stained with phosphotungstic acid. In contrast, no such elements were observed in Methanobacterium ruminantium.