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Ionization of protoplanetary disks by galactic cosmic rays,solar protons,and supernova remnants

Geoscience Frontiers 2017年第2期8卷 247-252页

作者： ryuho kataoka Tatsuhiko Sato National Institute of Polar Research 10-3 Midori-choTachikawaTokyo190-8513Japan SOKENDAI 10-3 Midori-choTachikawaTokyo190-8513Japan Japan Atomic Energy Agency Shirakata 2-4TokaiIbaraki319-1195Japan

Galactic cosmic rays and solar protons ionize the present terrestrial atmosphere,and the air showers are simulated by well-tested Monte-Carlo simulations,such as PHITS *** use the latest version of PHITS to evaluate the possible ionization of protoplanetary disks by galactic cosmic rays（GCRs）,solar protons,and by supernova *** attenuation length of GCR ionization is updated as 118 g cm^-2,which is approximately 20% larger than the popular *** and soft possible spectra of solar protons give comparable and 20% smaller attenuation lengths compared with those from standard GCR spectra,respectively,while the attenuation length is approximately 10% larger for supernova ***,all of the attenuation lengths become 10% larger in the compound gas of cosmic abundance,e.g.128 g cm^-2 for GCRs,which can affect the minimum estimate of the size of dead zones in protoplanetary disks when the incident flux is unusually high.

关键词： Galactic cosmic rays Solar protons Supernova remnants Young Sun Protoplanetary disk T Tauri stars

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Hypoxia-inducible factor 1 alpha and vascular endothelial growth factor overexpression in ischemic colitis

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World Journal of Gastroenterology 2005年第10期11卷 1535-1539页

作者： Tomoyuki Okuda Takeshi Azuma Masahiro Ohtani ryuho Masaki Yoshiyuki Ito Yukinao Yamazaki Shigeji Ito Masaru Kuriyama Second Department of Internal Medicine Department of Endoscopic Medicine Department of Internal Medicine

AIM: To examine the etiology and pathophysiology in human ischemic colitis from the viewpoint of ischemic factors such as hypoxia-inducible factor 1 alpha (HIF-1 alpha and vascular endothelial growth factor (VEGF). METHODS: Thirteen patients with ischemic colitis and 21 normal controls underwent colonoscopy. The follow-up colonoscopy was performed in 8 patients at 7 to 10 d after the occurrence of ischemic colitis. Biopsy samples were subjected to real-time RT-PCR and immunohistochemistry to detect the expression of HIF-1 alpha and VEGF. RESULTS: HIF-1 alpha and VEGF expression were found in the normal colon tissues by RT-PCR and immunohistochemistry. HIF-1 alpha and VEGF were overexpressed in the lesions of ischemic colitis. Overexpressed HIF-1 alpha and VEGF RNA quickly decreased to the normal level in the scar regions at 7 to 10 d after the occurrence of ischemic colitis. CONCLUSION: Constant expression of HIF-1 alpha and VEGF in normal human colon tissue suggested that HIF-1 alpha and VEGF play an important role in maintaining tissue integrity. We confirmed the ischemic crisis in ischemic colitis at the molecular level, demonstrating overexpression of HIF-1 alpha and VEGF in ischemic lesions. These ischemic factors may play an important role in the pathophysiology of ischemic colitis.

关键词： Ischemic colitis HIF-1 alpha VEGF

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