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RNA molecules of all species contain modified nucleotides and particularly m5U residues. The vertebrate mitochondrial small subunit rRNA contains m5U nucleotide in a unique site. In this work we found an enzyme, TRMT2B, responsible for the formation of this nucleotide and m5U residues in a number of mitochondrial tRNA species. Inactivation of the Trmt2B gene leads to a reduction of the activity of respiratory chain complexes I, III and IV, containing the subunits synthesized by the mitochondrial protein synthesis apparatus. Comparative sequence analysis of m5U-specific RNA methyltransferases revealed an unusual evolutionary pathway of TRMT2B formation which includes consecutive substrate specificity switches from the large subunit rRNA to tRNA and then to the small subunit rRNA. [ABSTRACT FROM AUTHOR]

In the fusion irradiation environment, helium created by transmutation will play an important role in the response of structural materials to neutron radiation damage. Atomistic simulations have been carried out using a new three-body He-Fe interatomic potential and the results have been compared to those obtained using two He-Fe pair potentials. In simulations with the three-body potential, helium interstitials are very mobile and multiple He interstitials can coalesce to form interstitial clusters which are also mobile. The He interstitial cluster binding energy is in good agreement with DFT calculations. If the He cluster is sufficiently large, it can create additional free volume by ejecting an Fe interstitial atom, creating a Frenkel pair. The corresponding vacancy is incorporated into the existing He cluster, and the resulting helium-vacancy cluster is not mobile. The ejected self-interstitial atom is mobile, but is trapped by the He-vacancy cluster. If additional helium atoms join a He-vacancy cluster, more Fe interstitials can be ejected and they are observed to form small interstitial clusters (nascent dislocation loop). Although multiple helium atoms can be trapped in a single vacancy, a vacancy containing only a small number of helium atoms can recombine with an Fe interstitial to recreate a helium interstitial cluster. The He binding energy with one of the He-Fe pair potentials (Wilson's) is much higher, leading to more rapid He clustering and Frenkel pair formation. Very little He clustering occurs with the second He-Fe pair potential. [ABSTRACT FROM AUTHOR]

A recently developed interatomic potential for He-Fe interactions includes a three-body term to stabilize the interstitial He defect in the tetrahedral position in the Fe bcc matrix and provides simultaneous agreement with the forces and energies of different atomic configurations as computed by first principles. This term makes a significant contribution to the static and dynamic properties of He in Fe. The implementation of this potential for atomistic simulations using molecular dynamics (MD) presented certain challenges which are discussed here to facilitate its further use in materials research, particularly to investigate the behavior of iron-based alloys that may be employed in fusion energy systems. Detailed results of an MD study comparing the new potential and alternate He-Fe pair potentials with different iron matrix potentials have been presented elsewhere to illustrate the impact of the He-Fe potential on He diffusion, helium clustering and the dynamics of He-vacancy clusters. [ABSTRACT FROM AUTHOR]

Objective: A previous study found that in Austria 50.3% physicians (m: 43.2%, f: 58.6%) have not attained their chosen specialty. We aimed to explore the policy – and attitude-related reasons for gender disparity in training post allocation. Methods: This cross-sectional study used a quantitative and a qualitative method. A self-administered 12-item questionnaire was sent twice to all 8127 licensed Viennese physicians. Physicians’ opinions regarding why the chosen medical specialty was not attained were analyzed. To estimate the responder bias respondents from the first and second mailing were compared. Results: A total of 2736 questionnaires (34%) were returned. When a specialty is favored by men, the chance for women to achieve that specialty decreases. According to the qualitative results, men were more often ready to accept training in a specialty different from the one originally desired. Female physicians were put at a disadvantage by consultants due to organizational considerations and sex-stereotyping. Conclusions: According to physicians’ self-reported opinions, consultants do not place female candidates at disadvantage as a result of an unconscious process but mainly based on reasoning about organizational aspects and sex-stereotyping. Several explanations for the phenomenon that men are more often ready to accept training in a specialty different from the one originally desired were identified. [ABSTRACT FROM AUTHOR]