How the arches on our feet evolved

The stiff human foot enables an efficient push upward when walking or running, and was critical in the evolution of the upright gait of humans. An international research team now explains how humans evolved two unique arches in the foot that help this uprightness1. The findings will be useful in improving the design of artificial limbs and robotic feet.

Unlike primates such as chimpanzees and gorillas, who have flexible flat feet, humans have stiff, arched feet. Researchers have mostly studied the medial longitudinal arch (MLA), which runs from the heel to the ball of the foot, ignoring the role of the transverse tarsal arch (TTA), which runs across the foot.

Studying mechanical mimics of the midfoot, human cadaveric feet and fossil foot bones, the researchers tried to find out the TTA’s contribution to stiffness of the human feet. The scientists, including a researcher from the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore, India, performed three-point bending tests on these models. They found that the TTA is responsible for more than 40% of the stiffness in our feet.

Tracking the growth and evolution of primate feet, including that of extinct human ancestors, the researchers found that only the genus Homo had fully developed arches (MLA and TTA). Together, these arches contribute to the stiffness of human foot, they report.

This renewed understanding of the human foot may improve the treatment of flatfoot disorders and the study of foot function in human motion, the researchers say.

References: 1. Venkadesan, M. et al. Stiffness. Source: https://www.natureasia.com/

Read More........→July 12, 2020

Radio signals from a distant galaxy find their way to Earth

An artist’s animation of galaxy with jets from a supermassive black hole. © NASA/ESA/STSc

Indian astrophysicists have discovered relic radio signals that are emanating from the edge of a distant low-mass galaxy cluster named Abell 16971.

Stemming from a merger of two galaxy clusters, such radio signals provide a unique opportunity to study matter and galaxy cluster physics that cannot be explored in laboratories. 

Since the Big Bang, galaxy cluster mergers are the most energetic events in the universe. Behaving like particle accelerators, such mergers release tremendous energy and accelerate electrons close to the speed of light, eventually generating tsunami-like shock waves. These waves then reach the edge of clusters and emit relic radio signals.

Relics are common in massive merging clusters. But only a few relics have been detected in low-mass clusters. 

While scanning the Northern Sky with the LOFAR Two-metre Sky Survey (LoTSS), an array of radio telescopes, the scientists from the Savitribai Phule Pune University and the National centre for radio Astrophysics of Tata Institute of Fundamental Research, both in Pune, India, accidentally discovered Abell 1697. They observed that the cluster is moving away from us. The cluster is home to 84 galaxies. 

Radio and optical images reveal that the radio emission from the cluster is purely diffuse in nature. Survey provides reasonable evidence that the structure is a peripheral relic. The diffuse radio emission has very low surface brightness.

Analysis indicates that the radio emission is a radio phoenix, a special type of relic radio signal generated by fossil electrons from the past events of radio galaxies.

References

1. Paul, S. et al. Radio-relic and the diffuse emission trail discovered in a low mass galaxy cluster Abell 1697. Astron. Astrophys. 633, A9 (2020) Source: https://www.natureasia.com/

Read More........→July 12, 2020