Estimation of synchrotron-radiation background based on a real beam orbit

Some high-energy experiments have suffered from synchrotron-radiation background. As a measure, we have developed a new calculation method of synchrotron radiation based on a real beam orbit, aiming at quantitative estimations and the construction of a possible alarm system for the background. An explanation and a demonstration of our method are given.Comment: 6 pages, 7 figures, 2 table

Spectral Continuity in Dense QCD

The vector mesons in three-flavor quark matter with chiral and diquark condensates are studied using the in-medium QCD sum rules. The diquark condensate leads to a mass splitting between the flavor-octet and flavor-singlet channels. At high density, the singlet vector meson disappears from the low-energy spectrum, while the octet vector mesons survive as light excitations with a mass comparable to the fermion gap. A possible connection between the light gluonic modes and the flavor-octet vector mesons at high density is also discussed.Comment: 4 pages, 3 figures; version to appear in Phys. Rev.

Single-particle spectral density of the unitary Fermi gas: Novel approach based on the operator product expansion, sum rules and the maximum entropy method

Making use of the operator product expansion, we derive a general class of sum rules for the imaginary part of the single-particle self-energy of the unitary Fermi gas. The sum rules are analyzed numerically with the help of the maximum entropy method, which allows us to extract the single-particle spectral density as a function of both energy and momentum. These spectral densities contain basic information on the properties of the unitary Fermi gas, such as the dispersion relation and the superfluid pairing gap, for which we obtain reasonable agreement with the available results based on quantum Monte-Carlo simulations.Comment: 44 pages, 11 figures, 2 tables; published versio

On the formation and processing of carbon and nitrogen compounds in carbonaceous chondrites

On the basis of chemical kinetic consideration, we examine processing of carbon and nitrogen compounds that leads to the linear relation between the logarithmic contents of C and N in carbonaceous chondrites : log N=a log C-b, found by A. SHIMOYAMA et al. (Chem. Lett., 10,2013,1987), where a>1 and b are constants. It is shown that the linear relation results from dissociation of organic polymer in the grains before accretion to parent body-sized objects by radiation that penetrates through the grains such as cosmic ray. Condensation of volatile molecules composed of C and N is also examined as a possible process to form precursors of organic compounds in carbonaceous chondrites. From an analysis of a model thermodynamic system, it is conjectured that this process can also realize the linear relation under certain conditions

Radioprotective Effect of Vitamin C as an Antioxidant

Vitamin C is known as a potent antioxidant. We studied vitamin C as a radioprotective agent, focusing on its antioxidative effect. When the body is exposed to radiation, free radicals and reactive oxygen species (ROS) are produced and oxidize cell components, resulting in cell damage. Vitamin C has the potential to scavenge these radical products, thereby protecting against radiation-induced cell damage. We investigated the effects of vitamin C on radiation-induced gastrointestinal (GI) syndrome in mice. The mice received whole-body irradiation followed by bone marrow transplantation 24 h after exposure. Despite avoiding bone marrow failure, the mice eventually died of GI syndrome. Pretreatment with per os administration of high-dose vitamin C effectively mitigated radiation-induced GI syndrome and improved mouse survivals, while per os post-treatment with vitamin C was ineffective, presumably due to impaired absorption from the radiation-damaged intestine. We also investigated the effect of post-exposure treatment with intraperitoneal administration of vitamin C on radiation-induced bone marrow dysfunction in mice. Intraperitoneal administration with high-dose vitamin C, even at 24 h after whole-body irradiation, was still effective in avoiding bone marrow dysfunction, thereby increasing mouse survival after radiation. In conclusion, administration of high-dose vitamin C effectively reduced the radiation lethality in mice

Sublimation Temperature of Circumstellar Dust Particles and Its Importance for Dust Ring Formation

Dust particles in orbit around a star drift toward the central star by the Poynting-Robertson effect and pile up by sublimation. We analytically derive the pile-up magnitude, adopting a simple model for optical cross sections. As a result, we find that the sublimation temperature of drifting dust particles plays the most important role in the pile-up rather than their optical property does. Dust particles with high sublimation temperature form a significant dust ring, which could be found in the vicinity of the sun through in-situ spacecraft measurements. While the existence of such a ring in a debris disk could not be identified in the spectral energy distribution (SED), the size of a dust-free zone shapes the SED. Since we analytically obtain the location and temperature of sublimation, these analytical formulae are useful to find such sublimation evidences.Comment: 9 pages, 5 figures, to be published in Earth Planets Spac

Numerical Analysis of Dynamic Behavior of Highly Saturated Sand Bed around Cylindrical Block under Cyclic Loading of Water Pressure

In this paper the theoretical procedure to analyze the dynamic behavior of highly saturated sand bed around a cylindrical block under the cyclic loading of water pressure is developed. The fundamental equations were derived for the axially symmetric coordinates. Then, the finite element equations were developed to solve these fundamental equations numerically. Finally, the numerical method was verified by experiments