Back Reaction of 4D Conformal Fields on Static Geometry

Static, spherically symmetric solutions to the semi-classical Einstein equation are studied, including the effect of the quantum energy-momentum tensor for conformal matters with 4D Weyl anomaly. Through both perturbative and non-perturbative methods, we show that the quantum effect can play a crucial role in shaping the near-horizon geometry, and that the existence of the horizon requires fine-tuning.Comment: 35 pages, minor modificatio

ヨツボシモンシデムシにおける養育行動の個体群間変異の探索と形質間相関の解明（英文）

Parental care is a prime example of altruism and has evolved across a wide range of taxa. Although parental care is common in mammals,birds, fishes and some invertebrate groups, there is considerable variation in reproductive effort (called parental investment) among species. Understanding the factors underlying the origin and maintenance of the variation contributes to uncovering the ultimate drivers of the emergence of complex family life and social behavior. Theoretical and empirical studies have shown that the optimal amount of parental investment for offspring exceeds that of its parent, and consequently the power balance between the parents and offspring determines the amount provided. Previous studies have reported individual traits in parents and offspring can influence investment, though in reality a set of coevolved traits in both parties will contribute to determine the optimal investment level. Hence, it is essential to investigate the correlation between multiple traits, and how this is related to the variation in parental investment. Herein, I use natural intraspecific variation in the amount of parental investment in a burying beetle Nicrophorus quadripunctatus to investigate the links between this variation and multiple parent and offspring traits. Results suggest that there was a genetic basis to parental feeding capacity and offspring solicitation ability, as I found a variation in post-hatching food feeding among populations. I also clarified how this variation is linked to the interrelationships among multiple traits on feeding amount. Variation in investment is particularly important for evolution, and these findings will help us understand the evolution of offspring rearing behavior.首都大学東京, 2019-03-25, 修士（理学）首都大学東

Fatigue experiment and assessment of butt-welded joints in steel structures considering misalignment and weld geometry effects

Luo P., Mashino Y., Matsuo Y., et al. Fatigue experiment and assessment of butt-welded joints in steel structures considering misalignment and weld geometry effects. International Journal of Fatigue 182, 108200 (2024); https://doi.org/10.1016/j.ijfatigue.2024.108200.This study investigates the fatigue behavior of butt-welded joints considering the effects of misalignments and weld geometries. Fourteen specimens were fabricated with varied assembly root gaps and axial eccentricities, and they were subjected to cyclic tensile loading with constant amplitude. Misalignments (both axial and angular) and weld geometries (including weld toe radius, flank angle, weld reinforcement height, and width) were measured using a 3D optical scanning system and subsequently used for fatigue evaluation in terms of fatigue crack locations and fatigue strength. The fatigue test results indicate a noticeable decrease in nominal stress fatigue strength as the assembled axial eccentricities increase, regardless of the assembled root gaps. However, the correlation between assembled root gaps and fatigue strength is not clear, as a larger assembled root gap corresponds to a flatter weld reinforcement on one hand and an increase in angular misalignment on the other hand. Several stress magnification factor (SMF) and stress concentration factor (SCF) formulae available in the literature are employed to characterize the combined effects of misalignment and weld geometries. The investigation results indicate that misalignments and weld geometries both play critical roles in the fatigue behavior of butt-welded joints. The combination of Remes and Varsta's SCF formula with Luo et al.'s SMF formula is the most recommended method due to its accuracy and robustness regarding the evaluation of both the fatigue crack locations and fatigue life in the investigated butt-welded joints