Object boundary location by region and contour deformation

Many applications in image analysis need to distinguish an object from its surroundings. The `snake' method (Kass, 1987) is a well known method to solve such problems by locating the object boundary from an initial plan, but it has the limitation that the distance between the initial plan and the object boundary should be `very small'. The authors present a two-step method, which combines region and contour deformation, to locate the boundary of an object from a designated initial boundary plan. First, they propose a new deformable region model to represent an object, and use the model to locate the boundary of the object by region deformation. This step fills the gap between a fairly rough initial plan and the `snake' method. The resulting boundary is then used as the initial plan of a `snake' method to further refine the boundary. The results of the method are shown in simulated images and MRI images of brain tumour patients     

Image compression in digital mammography: effects on computerized detection of subtle microcalcifications

Our previous receiver operating characteristic (ROC) study indicated that the detection accuracy of microcalcifications by radiologists is significantly reduced if mammograms are digitized at 0.1 mm x 0.1 mm. Our recent study also showed that detection accuracy by computer decreases as the pixel size increases from 0.035 mm x 0.035 mm. It is evident that very large matrix sizes have to be used for digitizing mammograms in order to preserve the information in the image. Efficient compression techniques will be needed to facilitate communication and archiving of digital mammograms. In this study, we evaluated two compression techniques: full frame discrete cosine transform (DCT) with entropy coding and Laplacian pyramid hierarchical coding (LPHC). The dependence of their efficiency on the compression parameters was investigated. The techniques were compared in terms of the trade-off between the bit rate and the detection accuracy of subtle microcalcifications by an automated detection algorithm. The mean-square errors in the reconstructed images were determined and the visual quality of the error images was examined. It was found that with the LPHC method, the highest compression ratio achieved without a significant degradation in the detectability was 3.6:1. The full frame DCT method with entropy coding provided a higher compression efficiency of 9.6:1 at comparable detection accuracy. The mean-square errors did not correlate with the detection accuracy of the microcalcifications. This study demonstrated the importance of determining the quality of the decompressed images by the specific requirements of the task for which the decompressed images are to be used. Further investigation is needed for selection of optimal compression technique for digital mammograms.     

Oncogene rearrangement in non-Hodgkin's lymphoma with a 14q+ chromosome of unknown origin

Southern blot analysis was performed with a panel of DNA probes to detect rearrangements of c-myc, bcl-1, bcl-2 and bcl-3 in 14 cases of B-cell non-Hodgkin's lymphoma (NHL) with a clonal cytogenetic rearrangement involving the chromosome 14q32 locus and no known donor chromosome [t(14;?)(q32;?)]. In our experience, 21% of all chromosomal abnormalities involving the 14q32 locus in B-cell NHL are of this type. We found oncogene rearrangements in five of the 14 cases: bcl-1 rearrangement on one mantle zone lymphoma, bcl-2 rearrangements in two follicular lymphomas, and c-myc rearrangements in two small noncleaved cell lymphomas. We conclude that a 14q32+ abnormality of unknown origin is a relatively frequent karyotypic finding in B-cell NHL. In one third of the cases, known oncogenes that have been previously described in reciprocal translocations involving the immunoglobulin heavy chain locus were shown to be involved in the 14q32+ abnormality. The translocations in the other cases are likely to have involved one of the above oncogenes with breakpoints not revealed by the probes employed, other known oncogenes, or oncogenes that have not yet been identified.     

Evaluation of the efficacy of sequential intravenous-oral administration of pefloxacin in community-acquired lower respiratory tract infections in patients with underlying conditions

We studied the efficacy of sequential intravenous-oral pefloxacin therapy in community-acquired lower respiratory tract infection in 24 patients with one or more underlying conditions. Twenty-eight patients were enrolled into the study but only 24 patients were evaluated. There were 16 males and 8 females with a mean age of 66.9 +/- 11.2 years (mean +/- SD, range 46 to 87 years). The underlying conditions present were bronchiectasis, chronic obstructive lung disease and diabetes mellitus. Patients who were older than 70 years but without any underlying condition were also enrolled. All received 4 days of intravenous pefloxacin 400 mg twice a day followed by oral pefloxacin 400 mg twice a day for another 10 days. Assessment of success was based on clinical, microbiological and radiological improvement. Pefloxacin produced 79.2% clinical cure rate. Another 8.3% showed improvement. Pefloxacin was well tolerated. There were few adverse effects and none of the patients required a change of antibiotic. Pefloxacin was an effective and well tolerated treatment for respiratory tract infection and had the advantage of broad in-vitro antibacterial activity, twice daily dosing and sequential availability in an intravenous and oral formulation.     

Use of somatic gene transfer to study lipoprotein metabolism in experimental animals in vivo

Genetic manipulations of experimental animals have provided valuable information on lipoprotein metabolism in vivo. Somatic gene transfer is a novel method for introducing foreign genes into animals in vivo. Adenovirus-mediated transfer of genes for the LDL receptor, the receptor-associated protein, apolipoprotein A-I, apolipoprotein E, cholesterol 7 alpha-hydroxylase, and apolipoprotein B messenger RNA editing protein has resulted in high-level expression of these transgenes in mice and hamsters, and the production of interesting animal models of lipoprotein metabolism. Somatic gene transfer is a valuable tool for analyzing the role of transgenes in lipoprotein metabolism in vivo and for exploring the potential use of specific transgenes for human gene therapy.     

The oxidative inducation test applied to medical PVC and other polymers

We have examined the applicability of this simple and effective test to polymer systems widely used in the medical industry. First, it was found that not every polymer examined exhibited a distinct onset of autocatalytic oxidation detectable by DSC. However, for cases where distinct onsets are found, powerful insights can be obtained. These included activation energy of the degradation, thermal oxidative shelf life prediction, and correlation, with product performances. Actual examples are presented to illustrate the utility of the test.     

Quartz microbalance study of4He and H2 on sodium

A quartz microbalance technique has been used to study the growth of⁴He and H₂ adsorbed on sodium. In contrast to cesium, adsorption of⁴He and H₂ do occur on a sodium surface.     

Mechanism for the Peritectic Reaction and Growth of Aligned Grains in YBa2Cu3O6+x

It is experimentally observed that the peritectic reaction, 211 + liquid → 123, can be driven essentially to completion in 1 h at an undercooling of only ∽30°C. The kinetic data, together with the observed microstructures, are inconsistent with the normal mechanism of the peritectic reaction. It is proposed that the mechanism of the reaction involves dissolution of 211 particles into the liquid and precipitation of solid 123. The aligned grain structure is explained through sympathetic nucleation of new 123 grains on existing grains.