Living Off Balance

Person walking in woods, balancing on a fallen tree

Imagine yourself walking at a normal pace down the sidewalk. Maybe you are on your way to class. The sidewalk has a little bit of a tilt causing your left foot to be higher than the right as it plants on the ground. Imagine how your body may compensate after a few minutes of walking on this path. We have all walked on uneven ground and began to feel the effects with sore knees or hips. But what if you felt this same way all the time even on perfectly flat terrain? This is the reality for those with leg length discrepancies.

Leg Length Discrepancy

A leg length discrepancy (LLD) is any difference in your legs compared to one another. This can be as small as a few millimeters or as large as a few centimeters. Leg length discrepancies can be caused by a number of things including genetics, trauma, or disease. Leg length discrepancies can be categorized in two ways; real and apparent LLD. Real leg length discrepancies are one in which the bony structures are measured to be two different lengths. Apparent leg length discrepancies are caused by other factors such as muscle or joint tightness making the limbs appear two different lengths.

Image depicting pelvic tilt when leg length discrepancy is present
Pelvic tilt caused by real leg length discrepancy

Hopping Along

The actual significance of a LLD on posture and gait depends heavily on the magnitude of the discrepancy. It is highly debated by researchers if a LLD of less than 2-3cm has physical effects on the body and if symptoms a patient is experiencing are due to another cause. R.K. Mahar and R.L. Kirby at Dalhousie University performed a study in which people without a LLD, asking them to stand on blocks simulating a real leg length discrepancy, the researchers saw a misalignment of the hips, an increase in knee flexion and a shift in the center of gravity.

In contrast D.C. Reid conducted a study for those with actual LLD and many did not complain of pain or feeling off balance and chose to not use corrective devices. The body is able to compensate for the difference over time to minimize the displacement of the center of mass of the body. It was also seen in a study done by Gross that athletes are more likely to correct smaller LLD than the average person due to the increased loads experienced during their activity.

Lift is placed in the sole of the shoe to correct moderate LLD
Shoe lift place in sole used to correct LLD

Fix it

For people that are experiencing pain because of the difference there are several ways to reduce the pain. For small discrepancies (less than 1cm) inserts can be placed into the shoe to even out the hips. For differences between 1cm and about 5cm a lift can be placed in the sole of the shoe for the same reason as the inserts. For some special cases or discrepancies larger than 5cm corrective surgery to lengthen or shorten the limb can be performed, but this is often used as a last resort.

Do Hammer-Shaped Heads Help Sharks Swim?

With their sandpaper skin, cartilage skeleton, electroreceptive sensors, and rows of dangerous teeth, sharks fascinate many people. However, even within this distinctive group the hammerhead sharks that make up the Sphyrnidae family have attracted a special attention due to the unusual shapes of their namesake heads, called cephalofoils. Several evolutionary benefits of the cephalofoil have been proposed by researchers. The wide hammer-shaped head may allow the shark to house more sensory receptors in its snout, to bludgeon prey, and to move and maneuver through the water more easily. Here we will address the question posed by the third theory: Does the cephalofoil found on hammerhead sharks provide an advantage in moving and maneuvering underwater?

Great Hammerhead Shark
Image of “Great Hammerhead Shark” by Wendell Reed showing a close-up of the cephalofoil.

Many advancements in the aviation and nautical industries have been developed from the study of sea creatures. There is certainly some potential that research into the mobility of sharks could someday be used as inspiration to advance locomotion technologies. In addition, a deeper understanding of the physiology and behavior of hammerhead sharks could help us to better preserve their habitat and species from endangerment – a crisis which some of them are already facing.

The theory that the cephalofoil provides advantages in forward swimming to hammerhead sharks relies on it supplying some hydrodynamic lift similar to the wing of an aircraft. Aircraft wings provide lift partly by creating a pressure difference between the top and bottom wing surfaces. An area of higher pressure on the bottom surface of a wing will generate upward lift. One study by Matthew Gaylord, Eric Blades, and Glenn Parsons applied a derivation of the Navier-Stokes equations – a set of partial differential equations for analyzing fluid flow – to water flow around digitized models of the heads of the eight most common species of hammerhead. It was found that in level, forward swimming there was some pressure differential that developed between the dorsal (top) and ventral (bottom) surfaces of the cephalofoil, but for each species it was very small and often in the direction to produce negative lift. The drag coefficients of the cephalofoil of each hammerhead species were then calculated and shown to increase as the size of the cephalofoil increased. The drag created by a cephalofoil was always much greater than the drags caused by the heads of a control group of non-hammerhead Carcharhinidae sharks.

Images of the pressure contours at zero angle of attack on the dorsal (top image) and ventral (bottom image) sides of the cephalofoil. The eight leftmost sharks are the hammerheads. Taken from Gaylord, Blades, Parsons.

However, the same study showed that the pressure difference between either surface of the cephalofoil did significantly increase in some species if the shark raised or lowered its head. This extra hydrodynamic force caused by the pressure differential at nonzero angles of attack would help the shark to turn its head up or down very quickly. This more explosive maneuverability was particularly present in the hammerheads that commonly feed on fish and less present in the species that feed predominantly on slower bottom dwellers. Another study by Stephen Kajiura, Jesica Forni, and Adam Summers theorized that the unbalanced, front-heavy cephalofoil may provide extra stability during tight turns by preventing banking. The unbalanced head would create a moment – or torque – to counteract the force from the tail that causes most sharks to roll into their turns. Not banking around turns could be important to some hammerhead sharks that often swim so close to the seafloor that banking into a turn could cause their head or fins to bump into the floor. It is likely that hammerhead sharks evolved the cephalofoil at least in part to provide more explosive and stable maneuvering.

Featured image “Hammerhead Shark” by bocagrandelasvegas.

Dolphin Magic or Dolphin Muscle?

Because of the film Bee Movie, many people at one point were intrigued by the idea that bumblebees should not physically be able to fly due to their large bodies and tiny wings. But, they fly anyway. Technology is advanced enough to study bee wing movement and determine that they produce enough lift to allow them to fly, disproving the previous notion. Similarly, Gray’s Paradox for a long time inferred that dolphins should not be able to swim nearly as fast as they do. But, they still consistently swim at speeds over twenty miles per hour. It was not until recent history that advancements allowed researchers to determine why they are able to reach such high speeds.

Gray’s Paradox

All the way back in 1936, Sir James Gray observed the high speeds dolphins could reach in the ocean. He calculated an approximation of the amount of power the dolphins would need to produce to sustain these speeds, based on the drag force on the dolphin as it travels through the water. Gray compared this to the amount of power he expected the dolphin to be able to produce. In order to compute this, Gray used muscle power data from oarsmen. When he compared the muscle mass of these oarsmen compared to dolphins, he determined that the power dolphins could produce was only about one seventh what was needed to travel at the high speeds of which they are capable.

Force Diagram, showing that the same forces that the swimming mammal applies to water are applied back on it. Allows observation of max speed to determine these forces.
This diagram shows that the drag force, D, thrust force, T, and net axial force, Fx, must be equal for the swimmer and the fluid. The lateral velocity, u, can be used to determine the resulting drag force, allowing researchers to estimate how much thrust is needed. Credit: [2]

And now we have arrived at Gray’s Paradox. What allows dolphins to move so quickly? To Gray and other researchers for most of a century, this was a mystery. If the assumptions they had made were correct, that would mean dolphins have some way of travelling through water more efficiently than was thought to be possible. This sparked a large amount of speculation into how dolphin skin could reduce the drag force of the water, which was originally believed to be the way Gray’s Paradox would be resolved.

Answering Questions while Creating More

Finally in 2008, Timothy Wei’s research team was able to definitively disprove Gray’s Paradox. He set up an experiment that would allow the force that dolphins exert to be measured. This mainly consisted of having dolphins swim through a curtain of bubbles in a tank. By recording at high resolution the movement of these bubbles as the dolphins swam by, the researchers determined the speed of the water around the dolphin as it traveled. With this information, Wei’s team showed that dolphins are able to produce over 300 pounds of force at one moment, and over longer periods of time 200 pounds of force. This is approximately ten times more force than Gray estimated.

Wei’s findings resolve Gray’s paradox by showing that dolphins have the ability to produce sufficient power from their tail movement to overcome the strong drag force of the water as they move at high speeds. However, this does not explain how dolphins produce so much power with their amount of muscle mass, which is still being examined. One idea is that this is caused by anaerobic muscle fibers that behave in different ways than in humans, and allow more power to be generated than Gray expected.

Future Plans: Investigating Force Generation

Timothy Wei plans to continue examining force generation in the swimming of other marine animals. This has the potential to provide more understanding of how marine animals evolved in their swimming aptitude. On the level of microbiology, this research could improve understanding of how dolphin and other animal muscles can perform such high levels of power generation over sustained periods of time.

Additional Reading and Sources

Arthritis is NOT Just For The Elderly: Early Signs Of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that, according to the Arthritis Foundation, affects 1.5 million people in the US. Women are 3 times more likely to develop RA and are usually diagnosed between ages 30 and 60, while men are rarely diagnosed before the age of 45 . Unlike osteoarthritis which is caused by wear and tear on joint cartilage over time, RA is caused by an overactive immune system that triggers unnecessary inflammation responses. One effect of this is that the body attacks its own joints causing swelling, stiffness, and chronic joint pain as well as irreversible damage. This limits joint mobility and decreases the quality of life for those impacted by it, especially those diagnosed as children or young adults.

This disease cannot be cured but treatments like medicine or dietary/ lifestyle changes are most effective when diagnosis happens early. When joint damage occurs it is irreversible, meaning the only treatment option is surgery. The joints most commonly affected in the early stages of this disease are finger joints which are usually the first sign of inflammation and will be the focus of this article. The image below shows the progression of finger joint damage in a patient with RA starting with no damage (a) to severe damage (c).

As an RA patient, a typical visit to your doctor would always include a pain/inflammation assessment. With a focus is on early stages of RA, fingers and hands would be the most important areas to look at. Each joint of focus would be felt by your doctor to check for swelling and tenderness, but the most important aspect is the patient’s self-assessment of inflammation and pain. It is important for patients to accurately assess their pain and mobility in order to find a medicine or treatment that works effectively. This was the focus of a study that was conducted on 52 RA patients (33 women and 19 men) which used a variety of tests in an attempt to quantify arthritis damage and compare it to the predictions made my patients.

The first test looked at range of motion for fingers flexed (in a fist) and extended (straightened). The next test measured grip strength in different positions like using a pencil, opening a jar or turning a key by using a device that measured the force produced by the hand in each position. Stiffness was measured visually, and pain levels were also recorded, but it should be noted that pain cannot accurately be quantified because pain tolerances vary among patients. The result of this study was that the patients predictions on grip strength and stiffness best correlated to the real results and were therefore the best predictors of hand function. This means that patient reports of strength and stiffness are the most accurate and helpful to be used by doctors when choosing medications or treatment plans.

Because joint damage from RA cannot be reversed, surgery is usually the only option to repair damaged joints, and even surgery will not bring back full mobility. Because RA treatments (both medicines and surgery options) are still very new there isn’t widely available or reliable data on the impact of hand surgery. Additionally, with the increasing use of the newer class of biologic drugs there has been a noticeable decrease in damage to the synovial tissue (the specialized tissue between the bones in any given joint) and the need for hand surgery has significantly decreased because of this. Overall, a variety of surgeries are available and there is almost always a tradeoff between mobility, vanity and elimination of pain. It is up to the patient, doctor, and surgeon to decide the best treatment option.

Overall, it is important to listen to your body and look out for early signs of RA to avoid lasting joint damage. This is especially important if you have a family history of RA. Early symptoms include, redness, pain, stiffness and swelling at joints, a lack of muscle strength, decreased range of motion/mobility, and even unexplained fatigue or fever.

References and Further Reading

the novel coronavirus: how an invisible invader halted the world

Last year the world changed. With modifications to daily life such as wearing masks and attending class online, a lot of what was common became uncommon. More severely, millions of deaths globally shook the world. All of this change and devastation can be attributed to a coronavirus variant that was shockingly good at two things… 1.) Stability outside of cells 2.) Breaching the lower respiratory tract. A few questions must be understood as to why this virus is so effective in its affinity towards destruction. First, How does COVID-19 penetrate a cell? How does COVID 19 replicate? Finally, why is COVID-19 able to survive outside of a cell so well?

Detailing of S spike Proteins on Coronavirus Molecule
Coronavirus Spike Illustration Provided by NIH

With regards to cellular penetration, Coronavirus has two main parts in order to enter a cell. The first part is the use of its spike-like proteins to bind to the outside of a cell, otherwise known as the cell’s surface receptors. This spiky outer layer of the coronavirus makes it easily bindable to a number of human cells. After an initial bind between the coronavirus and the cell’s surface receptors, the coronavirus is absorbed into the inside of the cell, analogous to the way an amoeba absorbs an organism. The second part of this process involves what is called protein priming. Before entering the cell, coronavirus primes the S protein through the host cell’s proteases. From there, the S protein allows for ACE-2 binding which can be thought of as the mode for physically transporting the coronavirus into the cell. The current variant of Coronavirus is exceptionally dangerous because its spike proteins are able to attach to cells in the lower respiratory tract, a very vulnerable system in many humans.

Scanning Electron Micrograph of Coronavirus infected tissue
Coronavirus Scanning Electron Micrograph From Patient

Once in the cell, coronavirus seeks to reproduce. In order to reproduce, Coronavirus seeks out ribosomes to make copies. The viral molecule carries the blueprint on how to convert RNA into more RNA via creating a polymerase. This polymerase reproduces the genetic RNA genome and ultimately forces the ribosomes to produce more Coronavirus molecules. Because there are millions of ribosomes in every human cell, it does not take long for this process to occur. One of the key modes of trying to treat people with extreme cases is medicine that targets this polymerase. The drug fakes out the polymerase into replicating genomic material that will not lead to greater virus production.

Coroanvirus armor and encasement illustrated.
Coronavirus armor and encasement illustration from

Finally, Coronavirus is exceptional at surviving outside of the cellular environment. It has been noted that in the right conditions (humid), coronavirus can survive on a given surface anywhere from a few hours to 9 days. On paper, the virus may only survive for a few hours while on glass, the virus can exist for 5 days. Why Coronavirus is able to survive on these surfaces relates back to its spike proteins. These proteins act as armor in protecting the genomic material inside the virus. If this armor is broken, the genome of the virus is spilled out as well the virus no longer having a physical form.

Understanding is the first step in disarming. By having a better understanding of how coronavirus binds and enters into cells, replicates, and survives in outside environments, better strategies to prevent the spread of this dangerous virus can be better developed.

The plant that hates to be touched

If you think you’re shy, you should meet the plant known to botanists as Mimosa pudica! Also known as a touch-me-not, shame plant, or humble plant, M. pudica reacts rapidly to external stimuli – such as being touched, changes in heat, or changes in light intensity. The reaction generally includes the folding in of the plant’s leaves and the stem bending downward. These movements make the touch-me-not one of the most curious plants on the planet.

A touch-me-not reacting to being touched! Source

So how does the M. pudica react so quickly? The answer lies in the pulvini and changes in turgor pressure. Pulvini are the thickened bases of leaf stalks and leaves that act as joints for the plant. Because of the pulvini, M. pudica is able to fold in any direction. This manifests itself as what we see as “drooping” of the stem and folding of the leaves.

Image pointing out the pulvini of a touch-me-not plant. The pulvini is the thickened base of a leaf stalk connecting it to the stem.
Pulvini of a touch-me-not. Source

Turgor pressure refers to the force exerted by a fluid in a cell onto the cell wall. In other words, the fluid – in this case, water – pushes the cell membrane up against the cell wall. When the turgor pressure is high, the plant is more rigid, as a healthy touch-me-not is before stimulus. When the turgor pressure decreases – caused by the external stimulus – the pulvini and leaves droop, resulting in the “shy” appearance of the plant.

The final piece of the puzzle of the shame plant is how and why external stimulus results in this rapid change of turgor pressure. This is caused by potassium and chlorine ions – K+ and Cl-, respectively. When the plant experiences external stimulus, the ions move out of the cell through the ion channel. Because of the resulting increased ion concentration outside of the cell – and the decreased concentration inside of the cell – water also moves out of the cell. Because turgor pressure relies on the force of the water against the cell wall, the pressure quickly decreases. This results in M. pudica drooping and folding its leaves.

The uniqueness of M. pudica comes from its ability to react quickly. This rapid reaction is a result of the water channels known as aquaporins. Aquaporins are selective channels that allow water molecules to move outside of the cell without allowing the movement of other ions/molecules. This allows the water molecules to move outside of the cell at a rapid pace – about 2 seconds.

Image showing water molecules moving through a cell membrane by way of an aquaporin.
Water molecules moving through a cell membrane by way of an aquaporin. Source

In summary, Mimosa pudica is a curious little plant with more to it than initially meets the eye. External stimulus results in the movement of ions from inside the plant cells to outside the plant cells. This change in ion concentration creates an imbalance, causing water to rapidly leave the cell through aquaporins. This decreases the turgor pressure, resulting in folding of leaves and the appearance of wilting through the use of the pulvini. Remember all of this next time you come across a touch-me-not; one little tap of its leaves will set off this entire chain reaction!

Sources and Further Reading:

Ahmad H, Sehgal S, Mishra A, Gupta R. Mimosa pudica L. (Laajvanti): An overview. Pharmacogn Rev. 2012;6(12):115-124. doi:10.4103/0973-7847.99945

Hagihara T, Toyota M. Mechanical Signaling in the Sensitive Plant Mimosa pudica L. Plants. 2020; 9(5):587.

Sampath, Bhuvaneshwari. “Molecular Magic behind the ‘Touch Me Not’ Plant.” Science India,

Song, K., Yeom, E. & Lee, S. Real-time imaging of pulvinus bending in Mimosa pudicaSci Rep 4, 6466 (2014).

Featured image:

Nash, Tainaya. “This Plant Moves When You Touch It, and the Video Is Wild.” House Beautiful, House Beautiful, 28 June 2019.

sticks and stones may break my bones but dirt will wash right off

There you are, sitting in the park eating your spaghetti picnic on your favorite picnic blanket when your pollen allergy acts up. You let out a sneeze powerful enough to compete with Aeolus’ bag of wind, but now your spaghetti is all over your favorite picnic blanket. You immediately go to rinse it off, but your fine Italian sauce has thoroughly soaked in. If only nature had a solution to keep a surface clean. Enter: the lotus leaf.

The lotus leaf is renowned for its ability to stay clean in murky environments. This characteristic of the plant is regularly attributed to its superhydrophobic surface features and chemistry. A superhydrophobic surface is a surface which can maintain a contact angle with water above 150o and is correlated with a low free surface energy—which really means water pools and rolls off rather than soaking into the surface.

Nearly perfectly spherical water droplet on an artificially prepared surface

Modified from Zorba et al. 2008

A key attribute of the superhydrophobic surface is a hierarchical micro- and nanostructure. The microstructure is composed of plant cells grown in little mounds known as a “papillae” with small channels for air flow in between called “stomata.” The nanostructure is composed of hair-like wax crystal towers (epicuticular wax) built on the peaks of the papillae topography. The elevated wax towers combined with the stomata trap air and reduce the contact area of the water with the surface. The epicuticular wax chemistry reduces the adhesion to the towers themselves by being naturally hydrophobic.

Graphic of water drop resting across uneven wax pillars on a lotus leaf

Modified from Zorba et al. 2008

The tips of the wax towers create the largest repelling forces which form larger contact angles, while shorter towers can actually produce adhesive forces that reduce the contact angle. If the air is displaced and filled with water, the contact angle will decrease due to the water-water adhesion which “pulls” the droplet to the surface. Similarly, if the surface is damaged, the wax can be removed and decrease the surface’s hydrophobicity. The wax is naturally soft material and prone to mechanical damage increasing water adhesion and reducing the self-cleaning abilities of the leaf.

The papillae topography is the key to the robustness of the lotus leaf hydrophobicity. The papillae create natural valleys and creases which—like the tops—are still densely packed with wax hairs. When the surface is impacted, only the top of the papillae are exposed to the mechanical force so the wax tubules in the valleys are left undeformed and maintain their hydrophobic characteristics.

Water beads on rain jacket

Photo by Chase Pellerin via Gear Patrol

Hydrophobic surfaces have many applications in everyday life, for example rain jackets and umbrellas perform their best when they are hydrophobic. Manufacturing processes rely on hydrophobic surfaces to reduce oxidation and stay clean in past-paced environments, and your favorite picnic blanket would be much less prone to spaghetti stains if it were hydrophobic. Nature has solutions to keeping surfaces clean; we just have to recognize them.

Oops I Did It Again: The Biomechanics Behind Repetitive Ankle Injuries

Ankle injuries – either sprains or fractures – are one of the most common sports traumas plaguing the US today. Sprains are overextensions or tears in ligaments.  Fractures, on the other hand, are broken bones.

Here, we will focus on sprains of which there are three grades. To help visualise a sprain, think of a Fruit By the Foot (the gummy fruit snack you may have eaten as a child). A Grade 1 sprain involves stretching like if you were to pull on either end of the fruit rope and small tears start to develop along the middle. A Grade 2 sprain develops when the tear is larger and originates from a side; a grade 3 sprain is a complete tear into two pieces.

A Little Background

The ankle joint, also known as the talocrural joint is a synovial hinge joint that mainly moves in dorsiflexion and plantarflexion 1. If you were sitting on the ground with both legs extended in front of you, dorsiflexion is the movement of your foot upwards toward your shin, and plantarflexion is the action associated with pointing your toes moving away from your body.

Video Explanation of Ankle Movements in Dorsiflexion and Plantarflexion

Sprains & Pains

The most common type of ligament injury are lateral ankle sprains or inversion sprains where the ankle joint over rotates in the outward direction, especially an inversion while in plantarflexion 2. Exercises that include running, jumping, and/or cutting put the athlete’s ankle at high risk for sprains. This is especially seen in soccer, football, basketball and volleyball players.

Depiction of ankle position with an inversion sprain. Light purple items are bones and have rectangular callouts, while red items are ligaments with circular call outs. Labeled items include: Tibia, Fibula, Talus, Cuboid, and Calcaneus bones as well as the ATFL, PTFL, and CFL (ligaments).
Figure 1 – Left Foot/Ankle in an over-rotation with main bones (in square callouts) and ligaments (in circle callouts) identified

Figure 1 above shows an ankle in the common and compromising position of an inversion sprain. The circled ATFL, PTFL, and CFL are ligaments in the joint, namely the Anterior Talo-Fibular ligament, the Posterior Talo-fibular ligament, and the Calcaneofibular ligament respectively. Additionally, the boxed call outs are bones in the foot.

Numbers show that close to 70% of patients that had experienced a lateral ankle sprain in the past repeated the same injury to their ankle1.

What is the medical explanation behind repeated ankle injuries?

One study by Doherty et al. followed emergency room visits for ankle injuries and found that 40% of patients with ankle sprains had to seek medical treatment for another ankle injury within the year. Yet, another statistic found that over half of people who experience ankle sprains don’t even go to a hospital.

Ankle sprains are sometimes deemed as a “walk-off injury“, or one that hurts momentarily but just needs a few minutes before resuming activity. However, many people suffer from prevalent and reoccurring ankle sprains. Officially dubbed Chronic Ankle Instability or Sprained Ankle Syndrome, this condition is characterised by a host of symptoms including pain, swelling, perceived and actual instability, balance issues, and joint weakness. Chronic Ankle Instability, or CAI more commonly, can also cause a decrease in physical activity, changes to walking or running form, onset arthritis, and problems with knees and hips due to overcompensation1.

The tried-and-true course of action to prevent CAI is efficient rehabilitation. A study showed that if the patient recovers fast enough, the body won’t change movement patterns.

Problem: Altered Movement Patterns

The changing of movement patterns in the ankle joint, or arthrokinematics1 is one of the main factors that contributes to CAI. The brain, like a protective mama bear, trains the body to operate (walk, run, jump) in a different manner to protect the strained ligaments. Over time, muscle memory kicks in and the compensation for ankle mobility becomes your new normal. This adoption of an incorrect form of walking, running, jumping, etc. can backfire and translate to repeated ankle injuries. This muscle memory has been identified as a neurosignature2 from Melzack’s neuromatrix of pain theory; however, this pain theory also describes how elimination of the pain, stress, or chronic symptoms associated with an ankle sprain can prevent reoccurrence – elimination, that is, through efficient rehab.

Solution: Efficient Rehabilitation

A quick recovery can be achieved through various muscle strengthening exercises from a licensed physical therapist or “ankle disk training,” which basically consists of a flat board mounted on a semi-circle. By standing on this unbalanced board, stability can be practiced as well as specific ligament targeting to build muscle. A more serious solution of ankle surgery showed a 90% success rate of mediating mechanical instability, but this is not a widely-practiced nor traditional treatment plan for CAI3. In fact, ankle taping and/or lace-up 3 bracing when exercising proved most helpful in preventing over rotations of the lateral ligaments.

the hairy feet of the gecko

Have you ever thought about what it would be like to walk on walls? If you’ve ever watched a Spiderman movie or watched a gecko maneuver around its habitat, you probably have. While geckos don’t fight crime, their climbing ability is as fantastic as that of any superhero. Geckos have one of the most unique climbing adaptations of any animal, and scientists are examining the source of this ability to see if human technology could one day achieve something similar.

Geckos are able to cling to almost any surface, no matter how smooth or rough it is. They are also able to detach quickly and easily from these surfaces as they climb. This climbing ability is due to tiny hairs, called setae, on the bottoms of their feet that can only be seen with a microscope. Each hair branches off into even smaller fibers called spatulae. Each gecko has about three million setae, and a billion spatulae! When the gecko places its foot on a surface, these hairs cling to the surface and form intermolecular bonds, called Van der Waals bonds, with the molecules of that surface. These bonds are strong enough to hold the gecko in place, but can be broken easily when the gecko lifts up its foot.

A close-up view of the bottom of a gecko foot, with the microscopic hairs visible.
Close-up of setae on gecko foot. Image by Science Photo Library

In addition to enabling the gecko to attach itself to surfaces, these hairs on the bottom of the gecko’s feet have the ability to clean themselves. If the gecko did not have some sort of ability to clean its feet, dust and dirt would get stuck on the gecko’s feet and break the connection between the feet and the surface. However, the hairs on the gecko’s feet are shaped so that it is difficult for water to stick to the feet. When the gecko gets water on its foot, the water rolls off of it and takes any particles of dirt with it.

Scientists have long been fascinated by the gecko’s ability to stick to surfaces, and many have been working on creating adhesives with fibers similar to the hairs on the bottom of the gecko’s feet. These adhesives are dry, like the gecko’s feet, and can be attached firmly and removed easily. The possibilities for application of adhesives like this are vast in number, and include everyday fasteners as well as use in electronics, robotics, and even outer space technology. One of the areas being explored by scientists is the use of these adhesives in the medical industry. The manufacture of gecko-hair fibers for bandages could mean farewell to the pain of removing a bandage, as well as the sticky residue left behind on your skin. This type of adhesive could even one day replace stitches after surgery.

Polymer fibrillar adhesive based on gecko foot Setae. Image by G.J. Shah, M. Sitti.

Most people probably don’t think about geckos very often apart from what they see in advertisements for car insurance. But for some scientists, these creatures hold the key to a world of possibilities. So next time you’re at the pet store, take a look in the lizard tanks and watch the geckos climb. Someday, thanks to those geckos, humans might be able to do the same thing.

Read more:

What Can Different Types of Facial Wrinkles Tell Us?

Few people enjoy having wrinkles. Some people spend a lot of time, money and efforts trying to reduce the wrinkles on their face, while others simply appreciate them as something naturally occurs with aging. Regardless, wrinkles are always associated with aging. However, if we look into what different types of wrinkles are and how they form, we will find that not all wrinkles are bad. Not all wrinkles are caused by aging, and not all wrinkles should be treated the same way. Here, we introduce different types of facial wrinkles categorized by plastic surgeon and their corresponding treatment.

A person smiling that shows some wrinkles on her face.
The wrinkles created by the motion of smiling are dynamic wrinkles. They will disappear once the smile stops. Credit: Masterfile.

In general, there are two main types of wrinkles, dynamic wrinkles and static wrinkles. Dynamic wrinkles are the type of wrinkles that only appear when you make expressions such as smiling, laughing, or frowning. These wrinkles disappear once your expressions stop. The facial muscles have enough elasticity to return to their original positions. These are temporary wrinkles that everyone may have, even little kids!

Static wrinkles, on the other hand, are wrinkles that form when your muscles cannot return to their original position due to gravity and loss of collagen and elastin. These wrinkles cannot disappear like the dynamic wrinkles. When the collagen fibers become thinner, the skin loses elasticity and gets more wrinkles, whose width and height grow with age. (Lemperle, 2001) Lemperle et al. from the University of California put these wrinkles into three categories.

Three hand-drawn figures that show textures of different wrinkles.
Figures that show the textural change of skin experiencing (a) superficial wrinkles, (b) mimetic wrinkles, (c) folds. Source: A Classification of Facial Wrinkles.

The first type is superficial wrinkles. These are the less severe wrinkles that only involve textural changes of the skin surface. These wrinkles lines are separate lines at first but will gradually group together. (Arumugam, 2015) Common causes are aging, excessive exposure to UV light, and gravity. Superficial wrinkles, according to Lemperle, can be reduced or removed by chemical peeling (applying chemical solution on the face to peel off the top layer and then grow it back), or laser resurfacing. (Lemperle, 2001)

A figure with 2 side-by-side photos that show the effect of laser resurfacing before and after the treatment. The wrinkles of the person's face reduces.
Before and after laser resurfacing. Credit: Tahoe Aesthetic Medicine.

The second type is mimetic wrinkles. These are more severe and visible dermal creasing. Major causes include aging and repeated dramatic facial expression. (Arumugam, 2015) Because the facial creasing is deeper, the reduction methods include more complicated procedures such as muscle resection (cut out a portion of muscle and inserted the shortened muscle at the same place), botulinum toxin (a neurotoxic protein), or skin filler injection. (Lemperle, 2001)

The picture shows a person's lower half of the face with dash line indicating where the nasolabial line is. A needle is pointing at the dash line mimicking the process of skin filler injection.
Skin filler injection to reduce the effects of nasolabial lines. Credit: Filling in Wrinkles Safely

The last type is folds, the part of the face where droopy skin overlaps. Folds and mimetic wrinkles usually occur together. To correct the overlapping skin, tightening procedures such as blepharoplasty (surgery that repairs droopy eyelids), face lift, or skin excision are needed. (Kligman, 1985)

Noticeably, researchers have discovered that wrinkles formation may be different by gender, race, etc. For example, women in general have finer and less apparent wrinkles than men because their skin is thinner and softer. (Wu, 1995) Asian skin connects more firmly to the tissues underneath because of its thicker dermis and higher collagen density. Therefore, the repetitive pulling of the skin surface affects wrinkles on Asians and Caucasians differently. (Ahn, 1999)

Wrinkles are nothing horrible. They are something that everyone has or will have in the future. There is nothing wrong with wanting to reduce the wrinkles on your face, either. Just remember that there are many types of wrinkles and each of them requires a bit of a different treatment. Spending some time finding the appropriate treatment will most likely save you more time, money, and effort in the future.


[1] Lemperle, Gottfried, et al. “A Classification of Facial Wrinkles.” Plastic and Reconstructive Surgery, vol. 108, no. 6, 2001, pp. 1751–1752., doi:10.1097/00006534-200111000-00050.

[2] Arumugam, P, et al. “Facial Forehead Wrinkles Detection using Colour based Skin Segmentation.” Advances in Natural and Applied Sciences, Aug. 2015, pp. 71–80., doi:10.22587/anas.

[3] Kligman, A.M., et al. “The Anatomy and Pathogenesis of Wrinkles.” British Journal of Dermatology, vol. 113, no. 1, 1985, pp. 37–42., doi:10.1111/j.1365-2133.1985.tb02042.x.

[4] Wu, Yin, et al. “A Dynamic Wrinkle Model in Facial Animation and Skin Ageing.” The Journal of Visualization and Computer Animation, vol. 6, no. 4, 1995, pp. 195–205., doi:10.1002/vis.4340060403.

[5] Ahn, Ki-Young, et al. “Botulinum Toxin A for the Treatment of Facial Hyperkinetic Wrinkle Lines in Koreans.” Plastic & Reconstructive Surgery, vol. 105, no. 2, 2000, pp. 778–784., doi:10.1097/00006534-200002000-00050.