95 research outputs found
The role of Schizosaccharomyces pombe SUMO ligases in genome stability
SUMOylation is a post-translational modification that affects a large number of proteins, many of which are nuclear. While the role of SUMOylation is beginning to be elucidated, it is clear that understanding the mechanisms that regulate the process is likely to be important. Control of the levels of SUMOylation is brought about through a balance of conjugating and deconjugating activities, i.e. of SUMO (small ubiquitin-related modifier) conjugators and ligases versus SUMO proteases. Although conjugation of SUMO to proteins can occur in the absence of a SUMO ligase, it is apparent that SUMO ligases facilitate the SUMOylation of specific subsets of proteins. Two SUMO ligases in Schizosaccharomyces pombe, Pli1 and Nse2, have been identified, both of which have roles in genome stability. We report here on a comparison between the properties of the two proteins and discuss potential roles for the proteins
Morphology of the testes and epididymal ducts in the pampas cat Leopardus colocolo (Molina, 1782)
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A method of generating k-fluorescence x-rays
For radiation protection purposes of k-fluorescence x-rays are useful for determining the energy response of instruments and dosimeters because they are nearly monoenergetic. the International Organization for Standardization (ISO) has specified the x-ray energies and radiator and filter materials for the production of such x-rays. There are two techniques useful for producing x-rays at approximately 17 and 59 keV; these techniques produce a situation that approximates the x-ray and gamma ray emissions of plutonium and americium isotopes. The Department of Energy Laboratory Accreditation Program (DOELAP) performance-testing standard for personnel dosimeters incorporates these k-fluorescence techniques. The Radiation Calibrations Facility at the Pacific Northwest Laboratory (PNL) has produced k-fluorescence x-rays for many years. Over the years, we have worked at improving this type of radiation for our performance-testing programs. This report describes the present geometry for the generation of k-fluorescence x-rays, a geometry proven more efficient in our facility. The exposure rate has increased and the beam uniformity has improved. Details of the geometry will be discussed
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Performance testing of extremity dosimeters against a draft standard
The assurance of worker radiation safety is directly related to the performance of personnel dosimetry. The US Department of Energy (DOE) has long recognized this critical relationship and has addressed this issue by instituting the DOE Laboratory Accreditation Program (DOELAP) which strives to improve the quality of personnel dosimetry through performance testing, dosimetry calibration, intercomparisons, evaluations and accreditations. One area of personnel dosimetry that has not been specifically addressed by DOELAP is extremity dosimeter testing. This task was directed at assessing the problems of implementing extremity dosimeter performance testing. A series of performance tests were made based on a draft standard written by the Health Physics Society Standards Committee (HPSSC) using extremity dosimeters currently in use at DOE and DOE contractor facilities. The results of this study indicate the need to incorporate performance testing of extremity dosimetry systems into DOELAP. Based on the results of this study, recommendations are made for improvements to the draft standard. 20 refs., 6 figs., 3 tabs
Surface effects on the microscopic adhesion mechanisms of styrene-isoprene-styrene + resin PSA's
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