[en] The authors have developed a processing protocol for isonitrile SPECT images. Transverse sections were reconstructed with the use of high-resolution filter. An elliptical region of interest (ROI) was placed around midventricular long and short axis sections, automatically applied to every section, and four long- and eight short-axis circumferential profiles were obtained. Improvements compared with the authors' thallium SPECT protocol in 15 normal volunteers and 12 patients with CAD included exclusion of nearby non-myocardial soft-tissue activity, more accurate superposition of ROIS in rest/exercise image pairs, higher spatial resolution, and a larger cavity with less distortion at the base and thinner walls, all of which enhanced diagnostic accuracy

[en] Here, we report the first measurement of differential and total cross sections for the γd→K⁰Λ(p) reaction, using data from the CLAS detector at the Thomas Jefferson National Accelerator Facility. Data collected during two separate experimental runs were studied with photon-energy coverage 0.8 - 3.6 GeV and 0.5 - 2.6 GeV, respectively. The two measurements are consistent giving confidence in the method and determination of systematic uncertainties. The cross sections are compared with predictions from the KAON-MAID theoretical model (without kaon exchange), which deviate from the data at higher W and at forward kaon angles. These data, along with previously published cross sections for K⁺Λ photoproduction, provide essential constraints on the nucleon resonance spectrum. A first partial wave analysis has been performed that describes the data without the introduction of new resonances.

[en] In a nested case-control study of nuclear workers, 82 brain cancer cases were compared with 328 matched controls to investigate the possible association with nonoccupational risk factors such as histories of epilepsy or head injury. We observed a moderately strong association between brain cancer occurrence and history of epilepsy (OR = 5.7, 95 per cent CI: 1.0, 32.1), but did not find a positive association with previous head injury (OR = 0.9, 95 per cent CI: 0.2, 4.2)

No abstract available

No abstract available

[en] Radioactive tracer studies are a sensitive means to detect occult pulmonary aspiration of gastric contents. A complication of diagnostic endoscopy is aspiration of contents even in fasted patients. The authors have studied 21 hospitalized patients who underwent elective endoscopy (END) for suspected UGI pathology. Fifteen minutes before END, and prior to pharygeal anesthesia, 1 mCi Tc-99m-sulfur colloid, added to the usual 30cc of simethicone routinely administered before END, was given orally. END was performed as usual and 2 hours later anterior 100,000 count images of the chest were obtained. All the studies were interpreted without history or clinical information. Fever developed within 24 hours (and septic shock in 1) in both patients with positive studies while no fever occurred in the remaining patients with negative studies (rho<.001). The authors conclude that oral radionuclide pulmonary aspiration studies may; detect aspiration not recognized by the endoscopist, reveal evidence of aspiration that preceeds adverse clinical signs and symptoms, and be influenced by systemic pre-END drugs known to affect GI secretions and motility

[en] Total photofission cross sections for ²³⁸U , ²³⁵U , ²³³U , ²³⁷Np , ²³²Th , and ^natPb have been measured simultaneously, using tagged photons in the energy range E_γ=0.17-3.84 GeV . This was the first experiment performed using the Photon Tagging Facility in Hall B at Jefferson Lab. Our results show that the photofission cross section for ²³⁸U relative to that for ²³⁷Np is about 80% over the entire energy range, implying the presence of important processes which compete with fission. If we assume that for ²³⁷Np the photofission probability is equal to unity, we observe a significant shadowing effect, starting below 1.5 GeV. (c) 2000 The American Physical Society

No abstract available

[en] A methodology is presented for the identification of circuit total dose response mechanisms in bipolar linear microcircuits irradiated at high and low dose rates. This methodology includes manual circuit analysis, circuit simulations with SPICE using extracted device parameters, and selective irradiations of portions of the circuit using a scanning electron microscope

[en] Acoustic Emission (AE) sensors were used to detect signals arising from a cylindrical roller bearing with artificial defects seeded onto the outer raceway. An SKF N204ECP roller bearing was placed between two double row spherical roller bearings, type SKF 22202E, and loaded between 0.29 and 1.79kN. Speed was constant at 5780rpm. High frequency analysis allowed insight into the condition of the bearings through the determination of an increase in the structural resonances of the system as the size of an artificial defect was increased. As higher loads were applied, frequencies around 100kHz were excited, indicating the release of AE possibly attributed to friction and the plastic deformation as peaks, induced through engraving of the raceway, were flattened and worn down. Sensitivity of AE to this level in bearings indicates the potential of the technique to detect the early stages of bearing failure during life tests. (paper)