Smart prosthetic hand combines both human and robot control

Zhuang et al. Shared human–robot proportional control of a dexterous myoelectric prosthesis. Nature Machine Intelligence, September 2019.

Holding an object in your hand might seem easy, but it’s actually a very complicated and challenging task; if, for instance, an object starts to slip, you typically have a couple of milliseconds to react. Scientists have been trying new approaches for improved control of robotic hands, particularly for use by amputees. A recent technology was able to combine individual finger control and automation for improved grasping and manipulation by successfully merging the fields of neuroengineering and robotics. This interdisciplinary approach was tested on three amputees and seven non-amputee subjects. The neuroengineers achieved the intended finger movement from muscular activity on the amputee’s stump, allowing for individual finger control of a prosthetic hand, which had never been done before. The robotics team enabled the robotic hand to take hold of objects and maintain contact with them for robust grasping. The amputee first performed a series of hand movements in order to train the algorithm through a machine learning paradigm. This taught the algorithm to decode user intention and translate it into finger movements of the prosthetic hand. Concurrently, sensors placed on the amputee’s stump detected muscular activity, which trained the algorithm to learn which hand movements corresponded to which patterns of muscular activity. Once the user’s intended finger movements were acquired, this information could then be used to control individual fingers on the prosthetic hand. When the user tried to grasp an object, the robotic automation initiated. The algorithm told the prosthetic hand to close its fingers when an object was in contact with sensors on the hand’s surface. This automatic grasping was designed to infer the shape of objects and grasp them based on tactile information alone, without any help of visual signals. The robotic hand has the ability to react within 400 milliseconds, and it is equipped with pressure sensors all along the fingers: it can react and stabilize the object before the brain can actually perceive that the object is slipping. While this promising technology can be used in in several neuro-prosthetic applications such as bionic hand prostheses and brain-to-machine interfaces, there are still many challenges remaining to implement this technology in a commercially available prosthetic hand for amputees. It is currently being tested and improved.

Cats securely bond with people, too

Vitale et al. Attachment bonds between domestic cats and humans. Current Biology, September 2019.

Dogs have long been regarded as man’s best friend. They’re sociable, faithful, and obedient. Cats, on the other hand, are often described as more aloof, mysterious, and independent. But a new study suggests that cats actually bond with their owners in similar ways to how humans and dogs bond with companions. The most established way to study human attachment behavior is to observe an infant’s response to a reunion with their caregiver following a brief absence in a novel environment. When a caregiver returns, secure infants quickly return to relaxed exploration while insecure individuals engage in excessive clinging or avoidance behavior. These tests had been previously run with humans, primates, and dogs; researchers decided to run the same test with cats. 79 kittens and 38 adult cats and their caregivers were recruited. During the test, an adult cat or kitten spent two minutes in a novel room with their caregiver followed by two minutes alone. Then, they had a two-minute reunion. The cats’ responses to seeing their owners again were classified into attachment styles. The results show that cats bond in a way that’s surprisingly similar to infants. In humans, 65% of infants are securely attached to their caregiver and domestic cats and kittens mirrored this, as about 65% of them securely bonded to their people. After the first round of tests, the researchers enrolled half the kittens used in the study in a training and socialization course. The other half served as a control group. Researchers then found the same results, suggesting the training did not have an effect on kittens’ attachment behavior toward their owners. This indicates that once a cat forms a bond, it seems to remain stable over time. This social flexibility may have helped facilitate the success of the species in human homes. It is still not clear what the factors are that shape the caretaker relationship, but it’s likely a miraculous complex mix of genetics, personality, and experience.

An efficient and green way to convert heat into electricity

Zheng et al. Paramagnon drag in high thermoelectric figure of merit Li-doped MnTe. Science Advances, September 2019.

A recent discovery could help scientists to develop more efficient ways to generate electricity from heat that would have been otherwise wasted, such as heat coming from car exhaust, industrial processes, and interplanetary space probes. In principle, magnetic fields can be used to generate electricity. If we move a magnet through a coil or wire, the magnet pushes and pulls electrons that create an electrical current. Magnets themselves don’t have energy, but they can control energy currents through the created magnetic field. The main problem with magnets is that when a magnet is heated up, it loses most of its magnetic properties and becomes a so-called paramagnet. Until this discovery, scientists believed that paramagnets couldn’t be used for generating electricity. In the new study, researchers found a way of designing thermoelectric semiconductors that can convert heat to electricity. The tiny particles in paramagnets, so called paramagnons, ended up producing enough spin to push an electron, for only a billionth of a millionth of a second – apparently long enough to make paramagnets viable energy-harvesters. This breakthrough in the conventional understanding of magnetic properties could lead to more research into how magnets and energy interact to potentially facilitate electricity production from heat that is otherwise wasted and oftentimes harmful to the environment.

At the same time as these events are happening almost simultaneously, information from my eyes and my finger is being sent to the brain so that my finger will move in the way I expect it to. For example, if the path of my finger’s movement is somehow blocked, my brain can redirect it.

However, the event described above is not that simple. Starting from the neurons and continuing until we reach the muscles, every element that acts during this process displays extraordinarily complex alterations at both cellular and molecular levels.

Consider muscle cells, since they are moderately well understood. Upon arriving at the muscle cell, the electrical impulse causes the voltage-sensitive calcium channels in specific compartments within the cell to open and release calcium into the cell. You might remember from high school biology that muscle contraction is the result of two proteins (myosin and actin) sliding over each other. Normally, actins are masked by proteins known as tropomyosin. During the waiting period, therefore, the interaction between myosin and actin, which leads to contraction, cannot occur. This is why the muscle cell releases calcium, for when calcium is free in the cell, it binds to tropomyosin and enables it to move. As a result, actin is free to interact with myosin.1

After that, millions of molecules containing energy, known as ATP, bind to millions of myosin proteins, and the muscle contracts. When the contraction ends, the freed-up calcium is stored once again in specific compartments. When calcium is not present, tropomyosins again mask the actin proteins, and millions of muscle cells revert to their initial position, ready to respond to another contraction.

I realize that all of this is hard for the average reader to understand. However, the events that take place are even more complicated.

Expressions like “ATP binds to myosin” and “calcium is stored in compartments” are, in fact, simplified ways of explaining a highly complex event. Since there is a reason for everything, our cells should contain something that is performing these functions and carrying out such events. If we expand this problem to its limits, we will have to understand that each cell contains a large set of rapid and specific chemical reactions that occur constantly and yet do not interfere with one another. Based on current scientific knowledge, we can say that enzymes conduct almost all reactions in a cell, and that DNA has all the necessary information to produce enzymes. Enzymes are protein molecules that speed up and regulate all of the reactions that take place in a cell. If there were no enzymes, the reaction that a cell carries out in seconds could only be completed in thousands of years, and consequently, life as we know it would not exist. Life requires that the correct enzyme be found in the correct place and at the correct concentration.

Based on this, let’s revisit the above example. When the electric impulse reaches the muscle cell and calcium ions are released, this and every external and internal signal is conveyed to the DNA through a mechanism that we are just beginning to appreciate: signal transduction. Later, RNA is produced in those regions of the DNA that are responsible for producing the enzymes that enable the cell to give the appropriate answer (RNA helps DNA to produce enzymes). The synthesis of the enzyme is regulated at various checkpoints, such as during RNA production or RNA translocation out of the nucleus by other enzymes.2 ATPase, one of the many enzymes produced, makes it possible to use ATP, while another enzyme makes sure that the ATPases are in the correct location in the cell. Meanwhile, in order to sustain life, thousands of other enzymes conduct various reactions at the correct time and place. Therefore, when I move my finger, the number of active elements increases enormously.

Let’s look at the finer points of the cell. Using a simple calculation, in which each number is much smaller than the actual number used, if we assume that one million cells perform some kind of action from the reception of the first impulse in the brain until the time the muscle contracts, and if we calculate that one thousand reactions occur in each of these cells, this means that one billion reactions are performed for the simple action of moving a finger. One billion reactions, in just one second. And at the same time, my heart is beating, new blood cells are being produced, my eyes are sending visual information to my brain, my kidneys are filtering my blood, my lungs are exchanging old air with new, fresh air, my digestive system is supplying the necessary nutrients to my blood stream, and much, much more. Moreover, all of these are continually taking place. The fact that all of these actions are occurring, again based on a very rough and simple calculation, means that maybe one trillion reactions are occurring every second. As a result, a person might feel that it is quite possible, at any instant, for this perfect machine-the human body-to fall apart.

Realizing this, one might actually find it hard to believe that he or she is really alive. For example, I would never believe that such a machine would work if I did not have the empirical knowledge that it does work. How, for example, can I believe that I can produce one trillion reactions every moment and never confuse one with another, that it takes one billion reactions to move my finger, and that one trillion gears are working by themselves without making any mistakes?

With this idea in mind, I see the following lines in Epitomes of Light: “Also, since a building that contains every kind of artwork and riches cannot exist without having been built by someone, the existence of this universe is intimately connected with the existence of the Builder. If someone thinks carefully, it is impossible to accept one without the other.”3 Upon reading these words, I start to realize that all of these gears are not working by themselves, but rather that every second all of the trillion gears are being regulated by the One for whom nothing is difficult.

Suddenly, I remember that whenever the names of God are recited, I hear the name al-Hayy right next to al-Qayyum: God is He besides Whom there is no god; He is al-Hayy (the Ever-Living), al-Qayyum (the One Who sustains and protects all that exists) (Qur’an 2:255). Putting al-Qayyum next to “life” indicates, at least to me, that every living being is kept alive at each instant by al-Qayyum. If His control over each person’s existence were to be lost for even one second, one trillion gears would become irreversibly mixed up and the body would fall apart instantly. While thanking God for all that He has given me, I realize that I cannot thank Him enough for even one gear.

References

1. Harvey Lodish et al., Molecular Cell Biology, New York: Scientific American Books, c1995, 1027-29.
2. Lewin, Benjamin, Genes VI, Oxford, NY: Oxford University Press, 1997, 847.
3. Nursi, S., Epitomes of Light: Mathnawi al-Nuriya: The Essentials of the Risale-i Nur, Kaynak A.S., 1999.