A major challenge in robotic design is enabling robots to immediately adapt to unexpected physical damage. However, conventional robots require considerable time (more than several tens of seconds) for adaptation because the process entails high computational costs. To overcome this problem, we focus on a brittle star—a primitive creature with expendable body parts. Brittle stars, most of which have five flexible arms, occasionally lose some of them and promptly coordinate the remaining arms to escape from predators. We adopted a synthetic approach to elucidate the essential mechanism underlying this resilient locomotion. Specifically, based on behavioural experiments involving brittle stars whose arms were amputated in various ways, we inferred the decentralized control mechanism that self-coordinates the arm motions by constructing a simple mathematical model. We implemented this mechanism in a brittle star-like robot and demonstrated that it adapts to unexpected physical damage within a few seconds by automatically coordinating its undamaged arms similar to brittle stars. Through the above-mentioned process, we found that physical interaction between arms plays an essential role for the resilient inter-arm coordination of brittle stars. This finding will help develop resilient robots that can work in inhospitable environments. Further, it provides insights into the essential mechanism of resilient coordinated motions characteristic of animal locomotion.
Ophiuroids locomote along the seafloor by coordinated rhythmic movements of multi-segmented arms. The mechanisms by which such coordinated movements are achieved are a focus of interest from the standpoints of neurobiology and robotics, because ophiuroids appear to lack a central nervous system that could exert centralized control over five arms. To explore the underlying mechanism of arm coordination, we examined the effects of selective anesthesia to various parts of the body of ophiuroids on locomotion. We observed the following: (1) anesthesia of the circumoral nerve ring completely blocked the initiation of locomotion; however, initiation of single arm movement, such as occurs during the retrieval of food, was unaffected, indicating that the inability to initiate locomotion was not due to the spread of the anesthetic agent. (2) During locomotion, the midsegments of the arms periodically made contact with the floor to elevate the disc. In contrast, the distal segments of the arms were pointed aborally and did not make contact with the floor. (3) When the midsegments of all arms were anesthetized, arm movements were rendered completely uncoordinated. In contrast, even when only one arm was left intact, inter-arm coordination was preserved. (4) Locomotion was unaffected by anesthesia of the distal arms. (5) A radial nerve block to the proximal region of an arm abolished coordination among the segments of that arm, rendering it motionless. These findings indicate that the circumoral nerve ring and radial nerves play different roles in intra- and inter-arm coordination in ophiuroids.
These results confirm the expression of Bcl-2 in T-cell lymphoma cell lines and indicate that it is suitable to detect feline Bcl-2 using an immunoblot assay. Pending further evaluation, Bcl-2 expression might be useful in the differential diagnosis of feline tumors.
The goal of this preliminary study was to examine the effect of participants' sexes on the temporal sequence of dominant sensations elicited by fruit-flavored teas. Twelve healthy young adults were assigned to male (n = 6) and female (n = 6) groups. Both groups were evaluated for four sensations using four fruit-flavored teas with 0.05 M sucrose using the temporal dominance of sensations (TDS) method. Only two sensations, sweetness and fruitiness, were consistently reported in the two groups. The male group first reported fruitiness and then sweetness as the dominant sensation following ingestion of the samples. Conversely, the female group reported these two dominant sensations in the reverse order. Significant dominant durations between the two sensations largely varied among the samples in both groups. These results suggest that there are sex-based differences in the temporal sequence of dominant sensations elicited by fruit-flavored teas as evaluated by the TDS method.
Non-invasive methods are normally preferred to conventional invasive methods when selecting suitable embryos to improve pregnancy rates after assisted reproduction techniques. One of the most recognized non-invasive methods is to examine the supernatants of embryo culture media. Soluble human leukocyte antigen, class I, G (sHLA-G) antigen is a non-classical class I molecule that has been widely considered as a marker of pregnancy failure or implantation success. In the current study of some Iranian patients, we examined the concentration of sHLA-G at different time points after intracytoplasmic sperm injection and compared the rates to the morphology and quality of the selected embryos. We showed that the concentration of sHLA-G increases over time in high-quality embryos. We conclude that there is a positive relationship between morphology, quality, and sHLA-G concentration. We suggest that this relationship can be used to increase the chance of a successful pregnancy.
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