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[en] The EUChinaGrid project is funded in the 6th framework program of the European Union. The project aims to support the interconnection and inter operability of Grids between Europe and China. To provide stable grid services, improve the reliability of the grid infrastructure and provide stake holders with views of the resources allowing to understand the current and historical status of the service packages like SAM, GridICE and GStat are used to monitor the EUChinaGrid infrastructure. In this paper, we discuss the use of these tools which are able to check if a given grid service works as expected for a given user or set of users on the different resources available on a grid. This paper also aims to evaluate the currently existing grid monitoring status in the EUChinaGrid infrastructure and provides thoughts about what could be improved in the future to increase the quality and quantity of monitoring information. (Author)
[en] Full angular distributions of the vector and tensor analyzing powers have been measured for 1H(d,γ)3He in the energy range 20 <, Ed 330 keV. A vapor condensed heavy ice target was bombarded by a 330 keV beam using Low Energy Beam Facility and Intense Polarized lon Source at TUNL. They rays were detected in two large volume HPGe crystals. We have extracted functional energy dependence of analyzing powers at each measured angle, i.e. 0 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees, and 135 degrees. The results will be compared with preliminary calculations based on the Refined Resonating Group Model (RRGM). It is expected that measurement of polarization observables for this reaction will provide new insights into the mechanism of low energy capture reaction e.g. the role of meson exchange currents, Coulomb effects, etc
[en] Purpose: Treatment-planning systems rely on computer intensive optimization algorithms in order to provide radiation dose localization. We are investigating a new optimization paradigm based on natural physical modeling and simulations, which tend to evolve in time and find the minimum energy state. In our research, we aim to match physical models with radiation therapy inverse planning problems, where the minimum energy state coincides with the optimal solution. As a prototype study, we have modeled the inverse planning of Gamma Knife radiosurgery using the dynamic interactions between charged particles and demonstrate the potential of the paradigm. Methods: For inverse planning of Gamma Knife radiosurgery: (1) positive charges are uniformly placed on the surface of tumors and critical structures. (2) The Gamma Knife dose kernels of 4mm, 8mm and 16mm radii are modeled as geometric objects with variable charges. (3) The number of shots per each kernel radii is obtained by solving a constrained integer-linear problem. (4) The shots are placed into the tumor volume and move under electrostatic forces. The simulation is performed until internal forces are zero or maximum iterations are reached. (5) Finally, non-negative least squares (NNLS) is used to calculate the beam-on times for each shot. Results: A 3D C-shaped tumor surrounding a spherical critical structure was used for testing the new optimization paradigm. These tests showed that charges spread out evenly covering the tumor while keeping distance from the critical structure, resulting in a high quality plan. Conclusion: We have developed a new paradigm for dose optimization based on the simulation of physical models. As prototype studies, we applied electrostatic models to Gamma Knife radiosurgery and demonstrated the potential of the new paradigm. Further research and fine-tuning of the model are underway. NSF CBET-0853157
[en] Brain stereotactic radiosurgery (SRS) and spine stereotactic body radiation therapy (SBRT) are commonly treated by a multidisciplinary team of neurosurgeons, radiation oncologists, and medical physicists. However the treatment objectives, constraints, and technical considerations involved can be quite different between the two techniques. In this interactive session an expert panel of speakers will present clinical brain SRS and spine SBRT cases in order to demonstrate real-world considerations for ensuring safe and accurate treatment delivery and to highlight the significant differences in approach for each treatment site. The session will include discussion of topic such as clinical indications, immobilization, target definition, normal tissue tolerance limits, and beam arrangements. Learning Objectives: Understand the differences in indications and dose/fractionation strategies for intracranial SRS and spine SBRT. Describe the different treatment modalities which can be used to deliver intracranial SRS and spine SBRT. Cite the major differences in treatment setup and delivery principles between intracranial and spine treatments. Identify key critical structures and clinical dosimetric tolerance levels for spine SBRT and intracranial SRS. Understand areas of ongoing work to standardize intracranial SRS and spine SBRT procedures. Schlesinger: Research support: Elekta Instruments, AB; D. Schlesinger, Elekta Instruments, AB - research support; B. Winey, No relevant external funding for this subject.
[en] The engineers in the modeling group in performance assessment at US DOE YMSCO have recently indicated an important concern about the results of the previous thermal-hydrologic calculations. This concern is that these calculations may incorporate some deficiencies in the current understanding of physical processes occurring in the drift at elevated temperatures and subresidual liquid saturations. They have found that the numerical modelers have used a modified capillary pressure function to fix arbitrarily the maximum capillary pressure for subresidual saturations. In addition, code developers have used certain numerical procedures to interpolate the liquid saturations ranging from 0 to residual saturation in numerical codes to avert numerical convergence problems. This kind of assumption may not represent the real conditions at the near-field of high-level radioactive nuclear waste repository due to a high thermal load from the waste packages. This report describes a study of the effects of the elevated temperature on the saturation capillary pressure
[en] Shanxi Province is abundant in coal reserve. Taiyuan Coal Gasification Corporation is a large sized union enterprise engaged in comprehensive use of coal in Shanxi province, and significant economic, social, environmental benefits have been brought forth with it. This leads people to believe that coal comprehensive utilization is the gateway for Shanxi Province in the fields of improvement of environment and development of economy
[en] Welding is a common method for repairing damaged ship propellers, especially by cavitation erosion. Reports on cavitation erosion and corrosion behavior of copper-manganese-aluminum (CMA) alloy weldment are sparse. In this paper, CMA weldment was prepared by tungsten inert gas welding (TIG), and its cavitation erosion behavior and corrosion behavior in 3.5% NaCl aqueous solution were studied by magnetostrictive vibratory device for cavitation erosion and electrochemical device, respectively. Results show that the weld zone (WZ) of the weldment exhibits better cavitation erosion and corrosion resistance than the heat-affected zone (HAZ) and the base metal. The cumulative mass loss of the WZ is only 1/4 that of the base metal. SEM analysis of eroded specimens reveals that the base metal is attacked most severely; the HAZ less and the WZ least. The microcracks causing cavitation damage initiate at the phase boundaries. Among the three zones of the weldment, the WZ is the noblest, its corrosion potential is -266 mV, while the HAZ, -284 mV, and the base metal, -279 mV, in about 60 h exposure to 3.5% NaCl aqueous solution. And its corrosion current density is the lowest, about 0.035 A m-2, while the HAZ, 0.078 A m-2, and the base metal, ±0.79 A m-2
[en] The profiles of MAE and BN for Co, Ni, oriented Fe-3.5% Si, and permalloy between -Hmax to +Hmax were investigated under 0.5 and 1 Hz triangle applied magnetic field. The profiles of Co (contained 180 deg. domain walls only) under different Hmax and different frequency show that the peak to peak voltage of MAE increase when the Hmax and frequency are increasing, and the shape of the profiles of MAE is similar to that of BN under the same condition. But for Ni the shapes of profiles of MAE and BN are not similar to each other. It means that the sources of MAE and BN for Co are the same i.e. 180 deg. domain wall motion. Not only the motion of non-180 deg. domain wall but also 180 deg. domain wall motion are the source of MAE. Besides that, domain wall nucleation and annihilation are also the sources of MAE
[en] The delivery techniques for SRS/SBRT have been under rapid developments in recent years, which pose new challenges to medical physicists ranging from planning and quality assurance to imaging and motion management. This educational course will provide a general overview of the latest delivery techniques in SRS/SBRT, and discuss the clinical processes to address the challenges of each technique with special emphasis on dedicated gamma-ray based device, robotic x-band linac-based system and conventional C-arm s-band linac-based SRS systems. (1). Gamma-ray based SRS/SRT: This is the gold standard of intracranial SRS. With the advent of precision imaging guidance and frameless patient positioning capabilities, novel stereoscopic CBCT and automatic dose adaption solution are introduced to the Gamma-ray based SRS for the first time. The first North American system has been approved by the US regulatory for patient treatments in the spring of 2016. (2). Robotic SRS/SBRT system: A number of technological milestones have been developed in the past few years, including variable aperture collimator, sequential optimization technique, and the time reduction technique. Recently, a new robotic model allows the option of a multi-leaf collimator. These technological advances have reduced the treatment time and improved dose conformity significantly and could potentially expand the application of radiosurgery for the treatment of targets not previously suitable for robotic SRS/SBRT or fractionated stereotactic radiotherapy. These technological advances have created new demanding mandates on hardware and patient quality assurance (QA) tasks, as well as the need for updating/educating the physicists in the community on these requirements. (3). Conventional Linac based treatments: Modulated arc therapy (MAT) has gained wide popularities in Linac-based treatments in recent years due to its high delivery efficiency and excellent dose conformities. Recently, MAT has been introduced to deliver highly conformal radiosurgery treatments to multiple targets simultaneously via a single isocenter to replace the conventional multi-iso multi-plan treatments. It becomes important to understand the advantages and limitations of this technique, and the pitfalls for implementing this technique in clinical practice. The planning process of single-iso multi-target MAT will be described, and its plan quality and delivery efficiency will be compared with multi-iso plans. The QA process for verifying such complex plans will be illustrated, and pitfalls in imaging and patient set up will be discussed. Overall, this session will focus on the following areas: 1) Update on the emerging technology in current SRS/SBRT delivery. 2) New developments in treatment planning and Quality Assurance program. 3) Imaging guidance and motion management. Learning Objectives: To understand the SRS/SBRT principles and its clinical applications, and gain knowledge on the emerging technologies in SRS/SBRT. To review planning concepts and useful tips in treatment planning. To learn about the imaging guidance procedures and the quality assurance program in SRS/SBRT. National Institutes of Health, Varian Medical System; L. Ren, The presenter is funded by National Institutes of Health and Varian Medical System.
[en] In this paper, the Laplace inversion technique, i.e., CONTIN program, has been used to analyze the positron lifetime spectra to obtain continuous annihilation rate distribution (ARD). Two kinds of materials were studied by measuring the positron ARD. In dealuminated Y-type zeolite, five peaks were observed, and the longest component is related to o-Ps lifetime in the secondary pores. In GaAs and in InP semiconductors, the native defects were successfully identified by the difference in positron ARD shape. More evidently, when InP sample was irradiated with high energy heavy ions, the positron ARD showed difference with different irradiation dose. These results indicate that the CONTIN analysis is a good complement to the PATFIT program. (author)