Results 1 - 10 of 87
Results 1 - 10 of 87. Search took: 0.019 seconds
|Sort by: date | relevance|
[en] Check valves are located in almost all safety and non-safety related fluid systems in a nuclear power plant. Malfunction or failure of these valves during plant operations, or in some cases under cold shutdown conditions, can seriously affect plant safety and result in costly, time-consuming maintenance. A major cause of check valve failure in the past has been excessive wear of internal components due to high disc flutter. Valve operation under conditions that cause the valve disc and hinge arm to oscillate or flutter can lead to degradations which, if undetected and not corrected, may result in malfunction or failure. Checkmate II, a portable, non-intrusive diagnostic system, has been developed to test various types of check valves using patented ultrasonic testing technology. The system comprises a computer, ultrasonic oscilloscope, transducers, and supporting hardware, and can identify many different phenomena, including: disc position and disc flutter; backstop and seat tapping; relative motion between hinge arm and disc; hinge pin wear and uneven hinge pin wear; disc stud wear and loosened stud nuts; combined stud and hinge pin wear, stuck and missing discs; broken springs. (author)
[en] Using published photometric data (Hilditch et al., Mem.R.ast. Soc.;82,part 2 (1976)) it is shown that there is a small, but significant amount of interstellar reddening for z < 400 pc within 150 of the north galactic pole. The distribution of reddening, which is both patchy and dependent on distance, agrees well with the observed (21 cm) distribution of neutral hydrogen. A gas: reddening ratio of (5.7 +- 0.8) x 1021 atom cm-2 mag-1 is obtained which is in good agreement with that obtained by Kerr and Knapp (IAU Symposium; No. 60: 179 (1974)) for all galactic latitudes. (author)
[en] Aim: The long term effects of TBI with children can be adverse and has resulted in a debate as to whether chemotherapy only based condition regimes could be used as an alternatives. The aim of this article is to critically evaluate the literature relating to the role of TBI as a conditioning regime in ALL in children, and if there are any alternatives to current practices or future developments. Method: Key databases were searched for terms: conditioning regimes, transplantation, TBI, whole body radiation, systemic irradiation, stem cell transplantation, hematopoietic stem cell, and transplant conditioning. Results: Thirteen research articles from a variety of publications and two guidance documents from several sources were uncovered for critical discussion. Discussion/conclusion: There is little evidence for chemotherapy only regimes in paediatric ALL, but the practice continues. Modulating doses to improve homogeneity and use of IGRT could hold a future solution to reducing long-term toxicity and maintain the efficacy of irradiation. - Highlights: • TBI regimes have adverse long term effects on development, particularly on growth. • Chemotherapy only regimes have long term effects that impact on development. • TBI is a superior to chemotherapy only conditioning regimes for paediatric ALL. • Research is being undertaken to refine TBI techniques to reduce overall toxicity.