| 1. |
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| 2. |
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| 3. |
- Abe, K., et al.
(författare)
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J-PARC Neutrino Beamline Upgrade Technical Design Report
- 2019
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Rapport (refereegranskat)abstract
- In this document, technical details of the upgrade plan of the J-PARC neutrino beamline for the extension of the T2K experiment are described. T2K has proposed to accumulate data corresponding to 2×1022 protons-on-target in the next decade, aiming at an initial observation of CP violation with 3σ or higher significance in the case of maximal CP violation. Methods to increase the neutrino beam intensity, which are necessary to achieve the proposed data increase, are described.
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| 4. |
- Abe, K., et al.
(författare)
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Neutron tagging following atmospheric neutrino events in a water Cherenkov detector
- 2022
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Ingår i: Journal of Instrumentation. - : Institute of Physics (IOP). - 1748-0221. ; 17:10
-
Tidskriftsartikel (refereegranskat)abstract
- We present the development of neutron-tagging techniques in Super-Kamiokande IV using a neural network analysis. The detection efficiency of neutron capture on hydrogen is estimated to be 26%, with a mis-tag rate of 0.016 per neutrino event. The uncertainty of the tagging efficiency is estimated to be 9.0%. Measurement of the tagging efficiency with data from an Americium-Beryllium calibration agrees with this value within 10%. The tagging procedure was performed on 3,244.4 days of SK-IV atmospheric neutrino data, identifying 18,091 neutrons in 26,473 neutrino events. The fitted neutron capture lifetime was measured as 218 +/- 9 mu s.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Sato, T., et al.
(författare)
-
Overview of particle and heavy ion transport code system PHITS
- 2015
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 82, s. 110-115
-
Tidskriftsartikel (refereegranskat)abstract
- A general purpose Monte Carlo Particle and Heavy Ion Transport code System, PHITS, is being developed through the collaboration of several institutes in Japan and Europe. The Japan Atomic Energy Agency is responsible for managing the entire project. PHITS can deal with the transport of nearly all particles, including neutrons, protons, heavy ions, photons, and electrons, over wide energy ranges using various nuclear reaction models and data libraries. It is written in Fortran language and can be executed on almost all computers. All components of PHITS such as its source, executable and data-library files are assembled in one package and then distributed to many countries via the Research Organization for Information Science and Technology, the Data Bank of the Organization for Economic Co-operation and Development's Nuclear Energy Agency, and the Radiation Safety Information Computational Center. More than 1500 researchers have been registered as PHITS users, and they apply the code to various research and development fields such as nuclear technology, accelerator design, medical physics, and cosmic-ray research. This paper briefly summarizes the physics models implemented in PHITS, and introduces some important functions useful for specific applications, such as an event generator mode and beam transport functions. (C) 2014 Elsevier Ltd. All rights reserved.
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| 11. |
- Sato, T., et al.
(författare)
-
Overview of Particle and Heavy Ion Transport Code System PHITS
- 2014
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Ingår i: Sna + Mc 2013 - Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo. - Les Ulis, France : EDP Sciences. ; , s. article no 06018-
-
Konferensbidrag (refereegranskat)abstract
- A general purpose Monte Carlo Particle and Heavy Ion Transport code System, PHITS, is being developed through the collaboration of several institutes in Japan and Europe. The Japan Atomic Energy Agency is responsible for managing the entire project. PHITS can deal with the transport of nearly all particles, including neutrons, protons, heavy ions, photons, and electrons, over wide energy ranges using various nuclear reaction models and data libraries. It is written in Fortran language and can be executed on almost all computers. All components of PHITS such as its source, executable and data-library files are assembled in one package and then distributed to many countries via the Research organization for Information Science and Technology, the Data Bank of the Organization for Economic Co-operation and Development's Nuclear Energy Agency, and the Radiation Safety Information Computational Center. More than 1,000 researchers have been registered as PHITS users, and they apply the code to various research and development fields such as nuclear technology, accelerator design, medical physics, and cosmic-ray research. This paper briefly summarizes the physics models implemented in PHITS, and introduces some important functions useful for specific applications, such as an event generator mode and beam transport functions.
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| 12. |
- Sato, T., et al.
(författare)
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Particle and Heavy Ion Transport code System, PHITS, version 2.52
- 2013
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Ingår i: Journal of Nuclear Science and Technology. - : Informa UK Limited. - 0022-3131 .- 1881-1248. ; 50:9, s. 913-923
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Tidskriftsartikel (refereegranskat)abstract
- An upgraded version of the Particle and Heavy Ion Transport code System, PHITS2.52, was developed and released to the public. The new version has been greatly improved from the previously released version, PHITS2.24, in terms of not only the code itself but also the contents of its package, such as the attached data libraries. In the new version, a higher accuracy of simulation was achieved by implementing several latest nuclear reaction models. The reliability of the simulation was improved by modifying both the algorithms for the electron-, positron-, and photon-transport simulations and the procedure for calculating the statistical uncertainties of the tally results. Estimation of the time evolution of radioactivity became feasible by incorporating the activation calculation program DCHAIN-SP into the new package. The efficiency of the simulation was also improved as a result of the implementation of shared-memory parallelization and the optimization of several time-consuming algorithms. Furthermore, a number of new user-support tools and functions that help users to intuitively and effectively perform PHITS simulations were developed and incorporated. Due to these improvements, PHITS is now a more powerful tool for particle transport simulation applicable to various research and development fields, such as nuclear technology, accelerator design, medical physics, and cosmic-ray research.
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| 13. |
- Watanabe, A., et al.
(författare)
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Association of aberrant ASNS imprinting with asparaginase sensitivity and chromosomal abnormality in childhood BCP-ALL
- 2020
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 136:20, s. 2319-2333
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Tidskriftsartikel (refereegranskat)abstract
- Karyotype is an important prognostic factor in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL), but the underlying pharmacogenomics remain unknown. Asparaginase is an integral component in current chemotherapy for childhood BCP-ALL. Asparaginase therapy depletes serum asparagine. Normal hematopoietic cells can produce asparagine by asparagine synthetase (ASNS) activity, but ALL cells are unable to synthesize adequate amounts of asparagine. The ASNS gene has a typical CpG island in its promoter. Thus, methylation of the ASNS CpG island could be one of the epigenetic mechanisms for ASNS gene silencing in BCP-ALL. To gain deep insights into the pharmacogenomics of asparaginase therapy, we investigated the association of ASNS methylation status with asparaginase sensitivity. The ASNS CpG island is largely unmethylated in normal hematopoietic cells, but it is allele-specifically methylated in BCP-ALL cells. The ASNS gene is located at 7q21, an evolutionally conserved imprinted gene cluster. ASNS methylation in childhood BCP-ALL is associated with an aberrant methylation of the imprinted gene cluster at 7q21. Aberrant methylation of mouse Asns and a syntenic imprinted gene cluster is also confirmed in leukemic spleen samples from ETV6-RUNX1 knockin mice. In 3 childhood BCP-ALL cohorts, ASNS is highly methylated in BCP-ALL patients with favorable karyotypes but is mostly unmethylated in BCP-ALL patients with poor prognostic karyotypes. Higher ASNS methylation is associated with higher L-asparaginase sensitivity in BCP-ALL through lower ASNS gene and protein expression levels. These observations demonstrate that silencing of the ASNS gene as a result of aberrant imprinting is a pharmacogenetic mechanism for the leukemia-specific activity of asparaginase therapy in BCP-ALL.
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| 14. |
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| 15. |
- Blondel, A., et al.
(författare)
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The SuperFGD Prototype charged particle beam tests
- 2020
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Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 15:12
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Tidskriftsartikel (refereegranskat)abstract
- A novel scintillator detector, the SuperFGD, has been selected as the main neutrino target for an upgrade of the T2K experiment ND280 near detector. The detector design will allow nearly 47r coverage for neutrino interactions at the near detector and will provide lower energy thresholds, significantly reducing systematic errors for the experiment. The SuperFGD is made of optically-isolated scintillator cubes of size 10 x 10 x 10 mm(3), providing the required spatial and energy resolution to reduce systematic uncertainties for future T2K runs. The SuperFGD for T2K will have close to two million cubes in a 1920 x 560 x 1840 mm(3) volume. A prototype made of 24 x 8 x 48 cubes was tested at a charged particle beamline at the CERN PS facility. The SuperFGD Prototype was instrumented with readout electronics similar to the future implementation for T2K. Results on electronics and detector response are reported in this paper, along with a discussion of the 3D reconstruction capabilities of this type of detector. Several physics analyses with the prototype data are also discussed, including a study of stopping protons.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Sato, T., et al.
(författare)
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Evaluation of dose rate reduction in a spacecraft compartment due to additional water shield
- 2011
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Ingår i: Cosmic Research (English translation of Kosimicheskie Issledovaniya). - 0010-9525 .- 1608-3075. ; 49:4, s. 319-324
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Tidskriftsartikel (refereegranskat)abstract
- The dose reduction rates brought about by the installation of additional water shielding in a spacecraft are calculated in the paper using the particles and heavy ion transport code system PHITS, which can deal with transport of all kinds of hadrons and heavy ions with energies up to 100 GeV/n in three-dimensional phase spaces. In the PHITS simulation, an imaginary spacecraft was irradiated isotropically by cosmic rays with charges up to 28 and energies up to 100 GeV/n, and the dose reduction rates due to water shielding were evaluated for 5 types of doses: the dose equivalents obtained from the LET and linear energy spectra, the dose equivalents to skin and red bone marrow, and the effective dose equivalent. The results of the simulation indicate that the dose reduction rates differ according to the type of dose evaluated. For example, 5 g/cm(2) water shielding reduces the effective dose equivalent and the LET dose equivalent by approximately 14% and 32%, respectively. Such degrees of dose reduction can be regarded to make water shielding worth the efforts required to install it.
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| 21. |
- Honek, J, et al.
(författare)
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Brown adipose tissue, thermogenesis, angiogenesis: pathophysiological aspects
- 2014
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Ingår i: Hormone molecular biology and clinical investigation. - : Walter de Gruyter GmbH. - 1868-1891 .- 1868-1883. ; 19:1, s. 5-11
-
Tidskriftsartikel (refereegranskat)abstract
- The number of obese and overweight individuals is globally rising, and obesity-associated disorders such as type 2 diabetes, cardiovascular disease and certain types of cancer are among the most common causes of death. While white adipose tissue is the key player in the storage of energy, active brown adipose tissue expends energy due to its thermogenic capacity. Expanding and activating brown adipose tissue using pharmacological approaches therefore might offer an attractive possibility for therapeutic intervention to counteract obesity and its consequences for metabolic health.
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| 22. |
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| 23. |
- Jonker, Sybrand J. T., et al.
(författare)
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Catalytic asymmetric propargyl- and allylboration of hydrazonoesters : a metal-free approach to sterically encumbered chiral alpha-amino acid derivatives
- 2018
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 54:91, s. 12852-12855
-
Tidskriftsartikel (refereegranskat)abstract
- A new asymmetric catalytic propargyl- and allylboration of hydrazonoesters is reported. The reactions utilize allenyl- and allylboronic acids in the presence of the inexpensive parent BINOL catalyst. The reactions can be performed under mild conditions (0 degrees C) without any metal catalyst or other additives affording sterically encumbered chiral -amino acids. This is the first metal-free method for the asymmetric propargyl- and allylboration of hydrazonoesters.
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| 24. |
- Lewis, Christopher T. A., et al.
(författare)
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Remodeling of skeletal muscle myosin metabolic states in hibernating mammals
- 2024
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- Hibernation is a period of metabolic suppression utilized by many small and large mammal species to survive during winter periods. As the underlying cellular and molecular mechanisms remain incompletely understood, our study aimed to determine whether skeletal muscle myosin and its metabolic efficiency undergo alterations during hibernation to optimize energy utilization. We isolated muscle fibers from small hibernators, Ictidomys tridecemlineatus and Eliomys quercinus and larger hibernators, Ursus arctos and Ursus americanus. We then conducted loaded Mant-ATP chase experiments alongside X-ray diffraction to measure resting myosin dynamics and its ATP demand. In parallel, we performed multiple proteomics analyses. Our results showed a preservation of myosin structure in U. arctos and U. americanus during hibernation, whilst in I. tridecemlineatus and E. quercinus, changes in myosin metabolic states during torpor unexpectedly led to higher levels in energy expenditure of type II, fast-twitch muscle fibers at ambient lab temperatures (20 °C). Upon repeating loaded Mant-ATP chase experiments at 8 °C (near the body temperature of torpid animals), we found that myosin ATP consumption in type II muscle fibers was reduced by 77-107% during torpor compared to active periods. Additionally, we observed Myh2 hyper-phosphorylation during torpor in I. tridecemilineatus, which was predicted to stabilize the myosin molecule. This may act as a potential molecular mechanism mitigating myosin-associated increases in skeletal muscle energy expenditure during periods of torpor in response to cold exposure. Altogether, we demonstrate that resting myosin is altered in hibernating mammals, contributing to significant changes to the ATP consumption of skeletal muscle. Additionally, we observe that it is further altered in response to cold exposure and highlight myosin as a potentially contributor to skeletal muscle non-shivering thermogenesis.
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| 25. |
- Lewis, Christopher T. A., et al.
(författare)
-
Remodelling of skeletal muscle myosin metabolic states in hibernating mammals
- 2023
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Hibernation is a period of metabolic suppression utilized by many small and large mammal species to survive during winter periods. As the underlying cellular and molecular mechanisms remain incompletely understood, our study aimed to determine whether skeletal muscle myosin and its metabolic efficiency undergo alterations during hibernation to optimize energy utilization. We isolated muscle fibers from small hibernators, Ictidomys tridecemlineatus and Eliomys quercinus and larger hibernators, Ursus arctos and Ursus americanus. We then conducted loaded Mant-ATP chase experiments alongside X-ray diffraction to measure resting myosin dynamics and its ATP demand. In parallel, we performed multiple proteomics analyses. Our results showed a preservation of myosin structure in U. arctos and U. americanus during hibernation, whilst in I. tridecemlineatus and E. quercinus, changes in myosin metabolic states during torpor unexpectedly led to higher levels in energy expenditure of type II, fast-twitch muscle fibers at ambient lab temperatures (20°C). Upon repeating loaded Mant-ATP chase experiments at 8°C (near the body temperature of torpid animals), we found that myosin ATP consumption in type II muscle fibers was reduced by 77-107% during torpor compared to active periods. Additionally, we observed Myh2 hyper-phosphorylation during torpor in I. tridecemilineatus, which was predicted to stabilize the myosin molecule. This may act as a potential molecular mechanism mitigating myosin-associated increases in skeletal muscle energy expenditure during periods of torpor in response to cold exposure. Altogether, we demonstrate that resting myosin is altered in hibernating mammals, contributing to significant changes to the ATP consumption of skeletal muscle. Additionally, we observe that it is further altered in response to cold exposure and highlight myosin as a potentially contributor to skeletal muscle non-shivering thermogenesis.
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| 26. |
- Mancusi, Davide, 1980, et al.
(författare)
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Calculation of Energy-Deposition Distributions and Microdosimetric Estimation of the Biological Effect of a 9C Beam
- 2009
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Ingår i: Radiation and Environmental Biophysics. - 1432-2099 .- 0301-634X. ; 48:2, s. 135-143
-
Tidskriftsartikel (refereegranskat)abstract
- Among the alternative beams being recently considered for external cancer radiotherapy, C-9 has received some attention because it is expected that its biological effectiveness could be boosted by the beta-delayed emission of two alpha particles and a proton that takes place at the ion-stopping site. Experiments have been performed to characterise this exotic beam physically and models have been developed to estimate quantitatively its biological effect. Here, the particle and heavy-ion transport code system (PHITS ) is used to calculate energy-deposition and linear energy transfer distributions for a C-9 beam in water and the results are compared with published data. Although PHITS fails to reproduce some of the features of the distributions, it suggests that the decay of C-9 contributes negligibly to the energy-deposition distributions, thus contradicting the previous interpretation of the measured data. We have also performed a microdosimetric calculation to estimate the biological effect of the decay, which was found to be negligible; previous microdosimetric Monte-Carlo calculations were found to be incorrect. An analytical argument, of geometrical nature, confirms this conclusion and gives a theoretical upper bound on the additional biological effectiveness of the decay. However, no explanation can be offered at present for the observed difference in the biological effectiveness between C-9 and C-12; the reproducibility of this surprising result will be verified in coming experiments.
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| 27. |
- Moeller, P., et al.
(författare)
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Axial and reflection asymmetry of the nuclear ground state
- 2008
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Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier BV. - 0092-640X. ; 94:5, s. 758-780
-
Tidskriftsartikel (refereegranskat)abstract
- More than a decade ago we published a calculation of nuclear ground-state masses and deformations in Atomic Data and Nuclear Data Tables [P. Moller, J.R. Nix, W.D. Myers, W.J. Swiatecki, At. Data Nucl. Data Tables 59 (1995) 185]. In this study, triaxial nuclear shapes were not considered. We have now enhanced our model and studied the influence of triaxial shape degrees of freedom on the nuclear ground-state potential-energy (mass) and ground-state shape. It turns out that a few hundred nuclei are affected to a varying degree with the largest effect, about 0.7 MeV, occurring near Ru-108. We provide here a table of the calculated effects of triaxial shape degrees of freedom. Although axial-asymmetry effects were not considered in the 1995 mass calculation, it did study the effects of reflection-asymmetric shape degrees of freedom (epsilon(3)) on nuclear masses. However, the magnitude of the effect was not tabulated. Here, we provide such a table. In addition we calculate the effect in a much improved fashion: we search a four-dimensional deformation space (epsilon(2), epsilon(3), epsilon(4), and epsilon(6)). This is now possible because the computational resources available to us today are more than 100,000 times better than at the time we calculated the mass table published in 1995. (C) 2008 Elsevier Inc. All rights reserved.
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| 28. |
- Niita, K., et al.
(författare)
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Applicability of the PHITS Code to Heavy Ion Accelerator Facilities
- 2011
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Ingår i: Journal of the Korean Physical Society. - : Korean Physical Society. - 0374-4884. ; 59:2, s. 1640-1643
-
Tidskriftsartikel (refereegranskat)abstract
- PHITS, a general-purpose Particle and Heavy Ion Transport code System, has been used for various research fields such as radiation science, accelerator and its shielding design, space research, medical application and material research. In this paper, we present an overview of the PHITS code, particularly the heavy ion reaction model included in the code and the capability of the transport of charged particles and heavy ions under magnetic field and discuss the applicability of the PHITS code to heavy ion accelerator facilities by showing some examples of the analysis.
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| 29. |
- Niita, K., et al.
(författare)
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Event Generator Models in the Particle and Heavy Ion Transport Code System; PHITS
- 2011
-
Ingår i: Journal of the Korean Physical Society. - : Korean Physical Society. - 0374-4884. ; 59:2, s. 827-832
-
Tidskriftsartikel (refereegranskat)abstract
- We present the event generator rnodels incorporated in the particle and heavy ion transport code system PHITS. For the high energy nuclear reactions, we discuss the QMD model and the INC model followed by the statistical decay model. For low energy neutron transport by using the nuclear data, we propose a new model, in which we combine the evaluated nuclear data and the reaction models so as to describe all ejectiles of collision keeping the energy and momentum conservation. By this new model, we can estimate new quantities which are related to the higher order correlations beyond one-body observable, for an example, the deposit energy distribution in a cell, which cannot be obtained by the transport calculation based on the Boltzmann equation with the evaluated nuclear data.
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| 30. |
- Okumura, H, et al.
(författare)
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New insights into the role of microheterogeneity of ZP3 during structural maturation of the avian equivalent of mammalian zona pellucida
- 2023
-
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 18:3, s. e0283087-
-
Tidskriftsartikel (refereegranskat)abstract
- The egg coat including mammalian zona pellucida (ZP) and the avian equivalent, i.e., inner-perivitelline layer (IPVL), is a specialized extracellular matrix being composed of the ZP glycoproteins and surrounds both pre-ovulatory oocytes and ovulated egg cells in vertebrates. The egg coat is well known for its potential importance in both the reproduction and early development, although the underlying molecular mechanisms remain to be fully elucidated. Interestingly, ZP3, one of the ZP-glycoprotein family members forming scaffolds of the egg-coat matrices with other ZP glycoproteins, exhibits extreme but distinctive microheterogeneity to form a large number of isoelectric-point isoforms at least in the chicken IPVL. In the present study, we performed three-dimensional confocal imaging and two-dimensional polyacrylamide-gel electrophoresis (2D-PAGE) of chicken IPVLs that were isolated from the ovarian follicles at different growth stages before ovulation. The results suggest that the relative proportions of the ZP3 isoforms are differentially altered during the structural maturation of the egg-coat matrices. Furthermore, tandem mass spectrometry (MS/MS) analyses and ZP1 binding assays against separated ZP3 isoforms demonstrated that each ZP3 isoform contains characteristic modifications, and there are large differences among ZP3 isoforms in the ZP1 binding affinities. These results suggest that the microheterogeneity of chicken ZP3 might be regulated to be associated with the formation of egg-coat matrices during the structural maturation of chicken IPVL. Our findings may provide new insights into molecular mechanisms of egg-coat assembly processes.
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| 31. |
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| 32. |
- Seki, T, et al.
(författare)
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Ablation of endothelial VEGFR1 improves metabolic dysfunction by inducing adipose tissue browning
- 2018
-
Ingår i: The Journal of experimental medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 215:2, s. 611-626
-
Tidskriftsartikel (refereegranskat)abstract
- Angiogenesis plays an instrumental role in the modulation of adipose tissue mass and metabolism. Targeting adipose vasculature provides an outstanding opportunity for treatment of obesity and metabolic disorders. Here, we report the physiological functions of VEGFR1 in the modulation of adipose angiogenesis, obesity, and global metabolism. Pharmacological inhibition and genetic deletion of endothelial VEGFR1 augmented adipose angiogenesis and browning of subcutaneous white adipose tissue, leading to elevated thermogenesis. In a diet-induced obesity model, endothelial-VEGFR1 deficiency demonstrated a potent anti-obesity effect by improving global metabolism. Along with metabolic changes, fatty liver and insulin sensitivity were also markedly improved in VEGFR1-deficient high fat diet (HFD)–fed mice. Together, our data indicate that targeting of VEGFR1 provides an exciting new opportunity for treatment of obesity and metabolic diseases, such as liver steatosis and type 2 diabetes.
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| 33. |
- Seki, T, et al.
(författare)
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Endothelial PDGF-CC regulates angiogenesis-dependent thermogenesis in beige fat
- 2016
-
Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7, s. 12152-
-
Tidskriftsartikel (refereegranskat)abstract
- Cold- and β3-adrenoceptor agonist-induced sympathetic activation leads to angiogenesis and UCP1-dependent thermogenesis in mouse brown and white adipose tissues. Here we show that endothelial production of PDGF-CC during white adipose tissue (WAT) angiogenesis regulates WAT browning. We find that genetic deletion of endothelial VEGFR2, knockout of the Pdgf-c gene or pharmacological blockade of PDGFR-α impair the WAT-beige transition. We further show that PDGF-CC stimulation upregulates UCP1 expression and acquisition of a beige phenotype in differentiated mouse WAT-PDGFR-α+ progenitor cells, as well as in human WAT-PDGFR-α+ adipocytes, supporting the physiological relevance of our findings. Our data reveal a paracrine mechanism by which angiogenic endothelial cells modulate adipocyte metabolism, which may provide new targets for the treatment of obesity and related metabolic diseases.
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| 34. |
- Sihver, Lembit, 1962, et al.
(författare)
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An update about recent developments of the PHITS code
- 2010
-
Ingår i: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 45:7, s. 892-899
-
Tidskriftsartikel (refereegranskat)abstract
- PHITS (Particle and Heavy-Ion Transport code System) is a general-purpose three-dimensional Monte Carlo code, developed and maintained by RIST, JAEA and KEK in Japan together with Sihver et al. at Chalmers in Sweden. PHITS can deal with the transports of all varieties of hadrons and heavy ions with energies up to around 100 GeV/nucleon, and in this paper the current status of PHITS is presented. We introduce a relativistically covariant version of JQMD, called R-JQMD, that features an improved ground state initialization algorithm, and we will present the introduction of electron and photon transport in PHITS using EGS5, which have increased the energy region for the photon and energy transport from up to around 3 GeV to up to several hundred GeV depending on the atomic number of the target. We show how the accuracy in dose and fluence calculations can be improved by using tabulated cross sections. Benchmarking of shielding and irradiation effects of high energy protons in different materials relevant for shielding of accelerator facilities is also presented. In particular, we show that PHITS can be used for estimating the dose received by aircrews and personnel in space. In recent years, many countries have issued regulations or recommendations to set annual dose limitations for aircrews. Since estimation of cosmic-ray spectra in the atmosphere is an essential issue for the evaluation of aviation doses, we have calculated these spectra using PHITS. The accuracy of the atmospheric propagation simulation of cosmic-ray performed by PHITS has been well verified by experimental cosmic-ray spectra taken under various conditions. Based on a comprehensive analysis of the simulation results, an analytical model called "PARMA" has been proposed for instantaneously estimating the atmospheric cosmic-ray spectra below the altitude of 20 km. We have also performed preliminary simulations of long-term dose distribution measurements at the ISS performed with the joint ESA-FSA experiment MATROSHKA-R (MTR-R) led by the Russian Federation Institute of Biomedical Problems (IMBP) and the ESA supported experiment MATROSHKA (MTR), led by the German Aerospace Center (DLR). For the purpose of examining the applicability of PHITS to the shielding design in space, the absorbed doses in a tissue equivalent water phantom inside an imaginary space vessel has been estimated for different shielding materials of different thicknesses. The results confirm previous results which indicate that PHITS is a suitable tool when performing shielding design studies of spacecrafts. (C) 2010 COSPAR. Published by Elsevier Ltd. All rights reserved.
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| 35. |
- Sihver, Lembit, 1962, et al.
(författare)
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PHITS - Applications to radiation biology and radiotherapy
- 2013
-
Ingår i: 13th International Varenna Conference on Nuclear Reaction Mechanisms, NRM 2012. - 2078-8835. - 9789290833826 ; , s. 497-502
-
Konferensbidrag (refereegranskat)abstract
- PHITS is a 3-dimensional general-purpose Monte Carlo code, which can transport of all varieties of hadrons and heavy ions with energies up to around 100 GeV/nucleon. To be able to estimate the biological damage from neutrons with PUTTS, a feature has been included to treat low energy neutron collisions as "events" which means that the energy and momentum is conserved in each event and makes it possible to extract the kinetic energy distributions of all the residual nuclei without using any local approximation. To estimate the direct biological effects of radiation, mathematical functions, for calculating the microdosmetric probability densities in macroscopic material, have been incorporated in PUTTS. This makes it possible to instantaneously calculate the probability densities of lineal and specific energies around the trajectories of high energetic charged particle tracks. A method for estimating the biological dose has also been established by using the improved PUTTS coupled to a microdosimetric kinetic model.
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| 36. |
- Sihver, Lembit, 1962, et al.
(författare)
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Recent developments and benchmarking of the PHITS code
- 2007
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Ingår i: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 40:9, s. 1320-1331
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Tidskriftsartikel (refereegranskat)abstract
- Many new options have recently been included in PHITS, e.g., to calculate LET distributions of particles in matter or energy-deposition distributions event by event and correlations between energy depositions in different regions. This makes it possible to calculate the effects of particle radiation on biological and non-biological materials, e.g., risk for single event upsets in electronic devices. As a part of an extensive ongoing benchmarking of PHITS, we have compared calculated partial projectile fragmentation cross sections with accelerator-based measurements from the reactions of 200-1000 MeV/n He-4, C-12, N-14, O-16, Ne-20, Si-28, Ar-40, and Fe-56 on polyethylene, carbon, aluminum, copper, tin and lead, with different thicknesses, using different total reaction cross section models in PHITS. We have compared simulated and measured Bragg and attenuation curves of 200 MeV/n C-12 in water, and neutron energy spectra, at different angles, from 100 to 400 MeV/n C-12 stopped in water. Bragg curves for 110, 140, 170, 190 and 225 MeV/n He-3 in water have been studied, as well as gamma-ray dose decay curves of activated Cu target bombarded by 400 and 800 MeV/n Ar-40. When using the default total reaction cross section model developed by Tripathi et al. (1996,1997 and 1999) [Tripathi, R.K., Cucinotta, F.A., Wilson, J.W. Accurate universal parameterization of absorption cross sections, Nucl. Instr. Methods B117, 347, 1996; Tripathi, R.K., Wilson, J.W., Cucinotta, F.A. Accurate universal parameterization of absorption cross sections II - neutron absorption cross sections. Nucl. Instr. Methods B129, 11, 1997; Tripathi, R.K., Cucinotta, F.A., Wilson, J.W. Accurate universal parameterization of absorption cross sections III - light systems. Nucl. Instr. Methods B155, 349, 1999.] the partial fragmentation cross sections appear to be systematically slightly underestimated by a factor which is independent on the fragment species within the same data set, and so do the simulated neutron energy spectra from selected heavy ion reactions; especially in the forward direction. The simulated attenuation and Bragg curves, however, show good agreement with measured ones. These observations stimulate further benchmarking to confirm the accuracy of the code and gives directions on possible improvements to be applied to the code in the near future. (C) 2007 Published by Elsevier Ltd on behalf of COSPAR.
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| 37. |
- Sublet, J. -Ch., et al.
(författare)
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Neutron-induced damage simulations : Beyond defect production cross-section, displacement per atom and iron-based metrics
- 2019
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Ingår i: The European Physical Journal Plus. - : Springer Berlin/Heidelberg. - 2190-5444. ; 134:7
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Forskningsöversikt (refereegranskat)abstract
- Nuclear interactions can be the source of atomic displacement and post-short-term cascade annealing defects in irradiated structural materials. Such quantities are derived from, or can be correlated to, nuclear kinematic simulations of primary atomic energy distributions spectra and the quantification of the numbers of secondary defects produced per primary as a function of the available recoils, residual and emitted, energies. Recoils kinematics of neutral, residual, charged and multi-particle emissions are now more rigorously treated based on modern, complete and enhanced nuclear data parsed in state of the art processing tools. Defect production metrics are the starting point in this complex problem of correlating and simulating the behaviour of materials under irradiation, as direct measurements are extremely improbable. The multi-scale dimensions (nuclear-atomic-molecular-material) of the simulation process is tackled from the Fermi gradation to provide the atomic- and meso-scale dimensions with better metrics relying upon a deeper understanding and modelling capabilities of the nuclear level. Detailed, segregated primary knock-on-atom metrics are now available as the starting point of further simulation processes of isolated and clustered defects in material lattices. This allows more materials, incident energy ranges and particles, and irradiations conditions to be explored, with sufficient data to adequately cover both standard applications and novel ones, such as advanced-fission, accelerators, nuclear medicine, space and fusion. This paper reviews the theory, describes the latest methodologies and metrics, and provides recommendations for standard and novel approaches.
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| 38. |
- Yang, YL, et al.
(författare)
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Discontinuation of anti-VEGF cancer therapy promotes metastasis through a liver revascularization mechanism
- 2016
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7, s. 12680-
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Tidskriftsartikel (refereegranskat)abstract
- The impact of discontinuation of anti-VEGF cancer therapy in promoting cancer metastasis is unknown. Here we show discontinuation of anti-VEGF treatment creates a time-window of profound structural changes of liver sinusoidal vasculatures, exhibiting hyper-permeability and enlarged open-pore sizes of the fenestrated endothelium and loss of VE-cadherin. The drug cessation caused highly leaky hepatic vasculatures permit tumour cell intravasation and extravasation. Discontinuation of an anti-VEGF antibody-based drug and sunitinib markedly promotes liver metastasis. Mechanistically, host hepatocyte, but not tumour cell-derived vascular endothelial growth factor (VEGF), is responsible for cancer metastasis. Deletion of hepatocyte VEGF markedly ablates the ‘off-drug’-induced metastasis. These findings provide mechanistic insights on anti-VEGF cessation-induced metastasis and raise a new challenge for uninterrupted and sustained antiangiogenic therapy for treatment of human cancers.
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