Atomic Energy of Canada Limited

About: Atomic Energy of Canada Limited is a company organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Neutron & Zirconium alloy. The organization has 4845 authors who have published 4826 publications receiving 102951 citations.

Solitons in the one-dimensional antiferromagnet CsCo Br 3

Abstract: The soliton response occurring at elevated temperatures in the one-dimensional Ising-type antiferromagnet CsCo${\mathrm{Br}}_{3}$ has been studied by neutron scattering. An inelastic peak is observed and identified as the Villain mode arising from the propagation of domain walls. Calculations have been made of the response from domain-wall-pair states and an extension of the first-order perturbation theory derived by Ishimura and Shiba. A reasonable account is obtained of the observed polarization and intensity of the scattering. The effect of collisions is seen to be increasingly important as the temperature is raised. The response near the zone center has been compared with the ideal-soliton-gas theory of Maki. The theoretical prediction, which has the form of a Lorentzian raised to the power $\frac{3}{2}$, gives a good qualitative description of the temperature dependence of the intensity and width of the scattering.

Neutron scattering from superfluid helium at large momentum transfers

Abstract: The inelastic scattering of thermal neutrons from liquid helium at 1.2 K has been measured for wave-vector transfers in the range 6.0 ≤ Q ≤ 12.0 »−1. Oscillations in the widths of the scattered-neutron distributions as a function of Q are observed to persist at least up to 12.0 »−1. A simple physical model suggests that these oscillations, which reflect the presence of final-state interactions and interference effects, have their origin in similar oscillations which occur in the He-He scattering cross section. Detailed measurements at Q = 10.0»−1 show no evidence of a well-defined condensate peak, and calculations suggest that Q values in the range 50–100 »−1 or greater may be required to observe a separate condensate component in the line shape. A method is developed for eliminating a major part of the effects of final-state interactions from the Doppler part of the distributions, and the corrected data at Q = 10.0 »−1 are analyzed to determine the momentum distribution in liquid helium at 1.2 K. The resulting distribution is found to be non-Gaussian with a well-defined high-momentum tail. The result is compared with the momentum distribution obtained recently by Mook from thermal neutron time-of-flight data near Q = 15 »−1 and with theoretical calculations of McMillan and of Kalos.

A critical role of toll-like receptor 4 (TLR4) and its' in vivo ligands in basal radio-resistance.

Abstract: Toll-like receptor-4 (TLR4) plays a critical role in innate and acquired immunity, but its role in radio-resistance is unknown. We used TLR4 knockout (KO,−/−) mice and gut commensal depletion methods, to test the influence of TLR4 and its' in vivo agonist on basal radio-resistance. We found that mice deficient in TLR4 were more susceptible to IR-induced mortality and morbidity. Mortality of TLR4-deficient mice after IR was associated with a severe and persistent bone marrow cell loss. Injection of lipopolysaccharide into normal mice, which is known to activate TLR4 in vivo, induced radio-resistance. Moreover, TLR4 in vivo ligands are required for basal radio-resistance. We found that exposure to radiation leads to significant endotoxemia that also confers endogenous protection from irradiation. The circulating endotoxins appear to originate from the gut, as sterilization of the gut with antibiotics lead to increased mortality from radiation. Further data indicated that Myd88, but not TRIF, may be the critical adaptor in TLR4-induced radio-resistance. Taken together, these data strongly suggest that TLR4 plays a critical role in basal radio-resistance. Our data suggest, it is important not to give antibiotics that may sterilize the gut before the whole body irradiation. Further, these data also suggest that management of gut flora through antibiotic or possibly probiotic therapy may alter the innate response to the total body irradiation.