Enhancement of Balance in Strength, Ductility, and Stretch Flangeability by Two-Step Austempering in a 1000 MPa Grade Cold Rolled Bainitic Steel

The microstructural evolution and properties for varied austempering routes are investigated in a cold-rolled bainitic steel. Special attention is given to the effect of retained austenite (RA) in terms of its fraction, carbon concentration, and morphology resulting from different austempering routes on mechanical properties and stretch flangeability. Bimodal sized bainitic laths are provided, and the carbon concentration of RA maintains the highest value through the two-step austempering. Total elongation (TEL) is remarkably enhanced for the two-step austempering, deviating from the exponential relationship between tensile strength (TS) and TEL as maintained by the one-step austempering. Considering the two plateaus of the strain-hardening exponent, it is considered that the hierarchical stability of RA is provided by the two-step austempering, leading to the postponed necking point so as to improve the uniform elongation. Two-step austempering could provide more complete bainitic transformation as well as more stable film-like RA, supplying a promising way to improve the combination of strength, ductility, and stretch flangeability.

Sex Differences in Hierarchical Stability in a Formation of a Mixed-Sex Group of Rhesus Macaques

Forming groups of captive rhesus macaques (Macaca mulatta) is a common management practice. New formations of unfamiliar macaques can be costly, with high levels of trauma, particularly as intense aggression is used to establish a dominance hierarchy. Combining previous subgroups into one new group may be beneficial, as some individuals already have established dominance relationships. We tested this hypothesis by forming a new mixed-sex group of rhesus macaques that combined an established group of females with an established group of males. Prior to the mixed-sex group formation, both the female and male hierarchies had been stable for 3 y; after mixed-sex group formation these hierarchies were maintained by the females and were initially maintained by the males for 3 wks. However, the temporary hospitalization (due to a laceration caused by aggression) of the alpha male destabilized the male hierarchy. Age and weight then predicted male rank. Temporary hospitalizations resulted in rank changes for the males, evidenced by reversals in subordination signals. Thisstudy indicates that using established groups of familiar individuals may maintain female hierarchical stability in a mixed-sex group formation, but further research is needed to understand how to maintain and predict male hierarchical stability to reduce trauma. Improved knowledge of hierarchical stability would be invaluable to managers of large rhesus macaque groups and would help improve the welfare of captive rhesus macaques.

Analytical stability in the Caledonian Symmetric Five-Body Problem

In this paper, we develop an analytical stability criterion for a five-body symmetrical system, called the Caledonian Symmetric Five-Body Problem (CS5BP), which has two pairs of equal masses and a fifth mass located at the centre of mass. The CS5BP is a planar problem that is configured to utilise past–future symmetry and dynamical symmetry. The introduction of symmetries greatly reduces the dimensions of the five-body problem. Sundman’s inequality is applied to derive boundary surfaces to the allowed real motion of the system. This enables the derivation of a stability criterion valid for all time for the hierarchical stability of the CS5BP. We show that the hierarchical stability depends solely on the Szebehely constant $$C_0$$ C 0 which is a dimensionless function involving the total energy and angular momentum. We then explore the effect on the stability of the whole system of varying the relative sizes of the masses. The CS5BP is hierarchically stable for $$C_0 > 0.065946$$ C 0 > 0.065946 . This criterion can be applied in the investigation of the stability of quintuple hierarchical stellar systems and symmetrical planetary systems.

Assessing the reliability of an automated method for measuring dominance hierarchy in nonhuman primates

Among animals’ societies, dominance is an important social factor that influences inter-individual relationships. However, assessing dominance hierarchy can be a time-consuming activity which is potentially impeded by environmental factors, difficulties in the recognition of animals, or through the disturbance of animals during data collection. Here we took advantage of novel devices, Machines for Automated Learning and Testing (MALT), designed primarily to study nonhuman primates’ cognition - to additionally measure the social structure of a primate group. When working on a MALT, an animal can be replaced by another; which could reflect an asymmetric dominance relationship (or could happen by chance). To assess the reliability of our automated method, we analysed a sample of the automated conflicts with video scoring and found that 75% of these replacements include genuine forms of social displacements. We thus first designed a data filtering procedure to exclude events that should not be taken into account when automatically assessing social hierarchies in monkeys. Then, we analysed months of daily use of MALT by 25 semi-free ranging Tonkean macaques (Macaca tonkeana) and found that dominance relationships inferred from these interactions strongly correlate with the ones derived from observations of spontaneous agonistic interactions collected during the same time period. We demonstrate that this method can be used to assess the evolution of individual social status, as well as group-wide hierarchical stability longitudinally with minimal research labour. Further, it facilitates a continuous assessment of dominance hierarchies, even during unpredictable environmental or challenging social events. Altogether, this study supports the use of MALT as a reliable tool to automatically and dynamically assess social status within groups of nonhuman primates, including juveniles.