Physics and the Human Body: Fetal Brain Development

     I've wanted to go to medical school for the longest time, and I never truly understood why physics was a pre-requisite until actually taking a physics course in college. My studying for the MCAT this semester has further shown me that physics is extremely relevant to the human body and how it functions. Thus, I was not surprised to find that physics plays an important role in the development of our brains when searching for a news article. During development, the fetal brain is completely smooth and not at all like a more developed brain that has many folds. You may ask, well how does the brain develop into what we imagine when we hear the word "brain" then? The answer has been found to lie in the forces we have looked at so far in class.

    Tallinen et al. (2016) created a 3D printed model of a fetal brain in order to mimic how the brain folds during development. The authors describe how the folding of the brain is important to fit more tissue into a relatively small space but note that the way in which this happen was not well understood. The 3D printed brain was made of gel that expands in solution to mimic a growing fetal brain. As the gel expanded upon contact with solution, the "brain" compression of the gel occurred and formed folds similar to real life development. The compression of the tissue into the shape of a brain results from compression forces acting on the brain in response to increased volume of the tissue. The gel acting as white matter exerts compression forces as the gel mimicking the cortex expands. Therefore, the cortex must fold and reduce pressure while growing as a result of the forces applied by the surrounding tissues. This can be related to Newton's laws of forces because the growing tissue exerts a force on the surrounding tissue. The tissue the brain comes into contact with then exerts a force back on the brain during development leading to the creation of these folds. 

    Interestingly, the 3D printed brains developed very similarly to real life fetal brains at the same developmental stage. These results suggest that these forces are mainly responsible for the structure of the brain observed in vivo. The authors state that this finding can be important in better understanding the development of neurological disorders that impact the size of the brain. They also discuss how cortex thickness could impact the compression forces and brain development. Thus, an understanding of physics is essential to understanding many biological processes. 

References

Maldarelli, C. (2016, February 3). You Have Basic Physics To Thank For Your Brain’s Funky Folds. 

Popular Science. https://www.popsci.com/thank-physics-for-your-brains-funky-folds/

Tallinen, T., Chung, J. Y., Rousseau, F., Girard, N., Lefèvre, J., & Mahadevan, L. (2016). 

On the growth and form of cortical convolutions. Nature Physics, 12(6), 588–593. 

          https://doi.org/10.1038/nphys3632

Physics in the News: Physics Applied to Cancer Treatments

Physics in the News: Physics Applied to Cancer Treatments

Being interested in oncology research, I found a recent article on dissolving microneedles that could extend access to skin cancer treatments. In this type of treatment method, drug-infused microneedles are inserted by intradermal injection, which utilize photodynamic therapy (PDT) to treat skin cancers. Researchers use fabricated arrays of 500 micrometer long needles mixed with a water-soluble polymer and a precursor of a PDT photosensitizer. In mice trials, dissolved microneedles were determined, by use of fluorescence confocal microscopy, to be more effective than topical creams at delivering the therapeutic agent to the tumor cells. Compared to mainstream topical creams, mice with microneedles arrays had a 200% increase in uptake of the photosensitizer precursor that was well diffused to the depths of the tumor. Because of this, researchers particularly find this method to be effective at treating thicker skin lesions. Additionally, this approach is quite cost-effective as it requires a lesser concentration of the precursor than the topical creams. This method also provides a non-invasive alternative to surgical procedures, which are currently the standard treatment method for non-melanoma skin cancers.

University of Sao Paulo’s Michelle Barreto Requena leads this PDT research where she is focusing on improving the photosensitizer to have the greatest effect possible. To do this, her team found that using the precursor, aminolaevulinic acid, allowed for greater penetration of tumor cells. ALA is taken up into tumor cells where it is then processed into the photosensitizer protoporphyrin IX form. By using dissolving microneedles, Requena and her colleagues are able to treat past superficial cells, which topical creams are limited to.

PDT works by using certain chemicals that can be activated by irradiation of a certain frequency of light, which is similar to the photoelectric effect discussed in introductory physics classes. The energy from photosensitizing chemicals converts molecular oxygen into reactive oxygen species to damage targeted cells and its DNA. By shining light on the tumor cells, physicians can specifically induce the cell death of cancerous cells while preserving nearby healthy tissue. 

(http://www.facialskincancer.com/html/photodynamic_therapy.php)

Michelle Barreto Requena holds a bachelor’s degree in physics and a Master of Science in biomolecular physics. She most recently finished her PhD program in the biomolecular physics program at the institute of Physics at the University of Sao Paulo in 2019. She now resides at the University of Sao Paulo as a post-doctoral researcher. 

From this article, it is clear to me physics is fundamental in medical research to improving quality of care, effectiveness of care, and healthcare equity.

Works Cited:

Marric, S. (2020, October 30). Dissolving microneedles could extend access to skin-cancer

    treatment. Physics World. Retrieved from https://physicsworld.com/a/dissolving

    microneedles-could-extend-access-to-skin-cancer-treatment/

Requena, M. B., Permana, A. D., Vollet‐Filho, J. D., González‐Vázquez, P., Garcia, M. R., de 

    Faria, C. M. G., Pratavieria, S., Donnelly R. F., & Bagnato, V. S. (2020). Dissolving microneedles containing aminolevulinic acid

    improves protoporphyrin IX distribution. Journal of Biophotonics.

How *Not* to Remove Water From Your Ears

    As someone who spent most of their childhood summers in pools and lakes, I know what it is like to suffer from Swimmer's ear. Swimmer's ear is a type of ear infection caused by an excess amount of water left in the ear canal. The water provides a moist environment for bacteria to grow, and if left unchecked, pain is sure to ensue. I tried everything to prevent this irksome feeling: lying on my side until the water drained out, plugging my nose and trying to breathe out, and even swinging my head left and right to dislodge the water. Sometimes these tricks worked, but most of the time they did not. And if they didn't work, I usually tried again. I never questioned what other effects these supposed remedies could have been having on my body. Now, new biophysical research makes me think that I should have.

   Research conducted by Anuj Baskota at Cornell University is shedding some light on the physics of water removal from the inner ear canal. Anuj is a senior who is studying biological engineering with a minor in biomedical engineering. He presented this work at the 72nd annual meeting of the American Physical Society Division of Fluid Dynamics in 2019. Specifically, his work surrounded the jerking motion that some people perform to force water out of their ears. By conducting a simple set that only used glass tubes of varying diameters (ear canal) and a spring (jerking motion), Anuj was able to mimic the movement of some unfortunate swimmers. After doing some easy calculations, he found that the acceleration needed to overcome the surface tension of water within the ear canal is around 10 g's. An acceleration like this is enough to cause major brain damage. Even worse, as the diameter of the "ear canal" decreased, a larger acceleration was needed. This has major implications when you think about children with smaller ear canals trying to remove water from their ears. It also makes you rethink the next strategy you use to get that pesky water out of your ear.

    The new research performed by Anuj Baskota at Cornell University not only discovered something new and pertinent to the biomedical field, but it also highlighted the fact that seemingly simple experimental designs and a creative mind are enough to make it happen.

Reference: "Acceleration-induced water ejection in the human ear canal" by Anuj Baskota, Seungho Kim, Hosung Kang, and Sunghwan Jung.

Zeptoseconds: the smallest ever unit of measurement used to describe time

In the late 1990’s, the term femtosecond was coined as a new unit of measurement in order to describe the speed at which bursts of laser light cause certain molecules change their conformations. Until recently, this phenomenon held the record for the shortest event ever recorded, and the femtosecond was the smallest unit of measurement used to describe time. 

            This record was broken on October 16^th by German physicist Reinhard Dörner. Dörner was born in 1961 and graduated from the JWG University of Frankfurt with a dual degree in physics and philosophy in 1988, at the age of 27. Dörner went on to complete his PhD in physics, also from the JWG University of Frankfurt, before spending part of the 1990’s working in California at the Lawrence Berkeley National Laboratory. Dörner has held a faculty position at the institute of nuclear physics at Goethe University Frankfurt since 2002. He has published over 420 papers involving topics including spectroscopy, atomic and ionization physics, the photoelectric effect, and the very same femtosecond laser technique popularized over twenty years ago, which his new discovery builds on. Dörner also developed the COLTRIMS reaction microscope, which is the tool of choice to observe ultrafast chemical reaction progress. This works by making use of patterns of ejected electrons and photons to create a percept of these processes.  

            Dörner’s latest breakthrough came when he measured the average time it takes for a single photon to cross the length of a hydrogen atom. Hydrogen exists in nature as a diatomic species (H₂). The two atoms are linked by a covalent bond, which is two aligned electrons. A device capable of exciting a single photon to X-rays wavelength was used to fire the single photon at the diatomic hydrogen. One single X-ray photon carries enough energy to excite both electrons to the point where they are ejected out of the diatomic hydrogen molecule. Ejection of the first electron results in measurable waves being created as the electron leaves. The same type of waves occur from photon contact with the electron bound to the second hydrogen atom quickly after. These two wave patterns, as well as the orientation of the hydrogen atoms can be measured using Dörner’s own COLTRIMS microscope. Dörner then used this data to determine the distance between the time the two wave patterns are sensed; which can be attributed to the difference in time from when the photon comes in contact with the electron belonging to the first hydrogen atom, and then the second. The time it takes for the photon to cross this distance, moving at the speed of light, was measured to be 247 zeptoseconds. This is equal to 2.47 x 10^-19seconds, and to date, represents the fastest event to ever be measured. So fast in fact, that the term zeptosecond was coined in order to describe the time elapsed using a unit with a magnitude greater than 1.

 

Sources:

1.     Staff, S. (2020, October 16). Zeptoseconds: New world record in short time measurement. Retrieved October 27, 2020, from https://phys.org/news/2020-10-zeptoseconds-world-short.html

2.     Physik Fachbereich 13. Retrieved October 27, 2020, from https://www.uni-frankfurt.de/45139800/Doerner

 

The Physics of New Life: The (failed) Apparatus for Facilitating Child Birth

In 1965, Charlotte and George Blonsky were granted a patent for an invention known as “The Apparatus for Facilitating Child Birth.” What’s so bad about “The Apparatus” you ask? It is your lucky day, you’re about to learn about a 60’s solution to extended labor, a process that has plagued women across the globe since the birth of humankind (pun intended). 

In the apparatus, the pregnant woman is first strapped onto a platform much like the flat surface of a merry-go-round. Her hands and feet are tied into place, along with a strap across her forehead and mid-section. Sounds pretty strange, right? Well, it only gets weirder. After being strapped in, the real fun (or terror) starts. The merry-go-round platform beneath the woman begins to spin. By using the properties of centrifugal force, the idea is that the birthing process will be quicker, with the baby ending up in a small, mesh bag once born.

Think of a tilt-a-whirl at an amusement park and the spinning of which causes riders to seem to “stick to” the walls of the ride. The force acting on riders is centrifugal force, which acts outwardly upon objects moving in a circular or curved path. The difference between centripetal and centrifugal force is shown in the diagram below. Now, instead of being a kid in an amusement park, imagine being a very pregnant woman in labor. You’re strapped in, and away you go. The same centrifugal force caused by the spinning of the tilt-a-whirl brings new life into the world. A beautiful sight isn’t it? Not quite.

Instead of spinning at around 3g’s, like the common tilt-a-whirl, the “Apparatus for Facilitating Child Birth” operates at around 7g’s. For reference, humans can withstand around 5g’s before passing out. As explained in the video below, 7g’s is around the same acceleration of a high-speed jet. Although the proposed physics of this device seems intact, and hypothetically birth should be quicker as a result of the centrifugal force pulling the baby from the womb, more than one serious problem is apparent with this device. One apparent issue would be death and pure terror for both mother and child, but alas Charlotte and George Blonsky went as far as to make a full sketch and prototype for the apparatus.

Luckily, only one prototype was ever created, and it was never actually used in labor or delivery of a child. Despite the obvious failure of the apparatus, all inventions, and scientists in general, must fail over and over and over again to ultimately find any success. It is these failures which teach us about ourselves and about scientific inquiry (maybe about some physics too, if we’re lucky!). 

Do-it-yourself snow tires

As we turn the corner into November, it’s getting to be the time of year when people in the northeast are preparing for winter. Covering swimming pools, pouring anti-freeze into pipes, and thinking about making an appointment to have snow tires put onto cars. Or, if you’re like me, you’re trying to think of a way to swap tires on your own in order to save a few bucks. For those of you who are not familiar with snow tires, they look just like regular tires, but can appear somewhat thicker. In trying to track down a new pair on my own, I was paying close attention to the diameter of a new set of wheels to ensure they were the same as my current pair. I began to think, why does this diameter matter so much? Surely it doesn’t have to be exact, tires wear down on their own over time, isn’t there room for error on the scale of a few centimeters? 

I learned that speedometers and odometers on cars such as mine make use of the rotational motion of the wheels to determine the overall speed of the car. A simplified diagram of an electronic speedometer is shown below:

Where a magnet in the wheel briefly comes in contact with an electronic sensor once every full revolution. This essentially measures the length of the period, or T; and from this the linear velocity can be determined. The computer on the car relates this measurement to the distance traveled because it is already preprogrammed with the radius of the wheels, and can extrapolate to define the velocity of a point on the outer wheel using a relationship similar to what we learned in class: v=(2πr)/T.

            If one were to install tires that were thinner or thicker than the original pair, the true radius of the wheels would be different than the car believes it is, and the calculated speed based on the measured T would be inaccurate. The same goes for the odometer, which uses the same function to keep track of total distance traveled. So, if I chose to replace my wheels with thicker ones, my cars odometer would underrepresent the total distance I travel, and my cars speedometer would display a speed slightly slower than what I am traveling. Thankfully, the computerized aspect of speedometers can be adjusted according to a change in the tire diameter, provided you have access to the proper equipment. 

            But, as a set of tires are used more and more, they wear down, and the overall radius of the wheel decreases slightly over time. So as a pair of tires is used, does the cars speedometer slowly accumulate error, overreporting the velocity, and the total distance traveled? The answer is yes. In fact, if you drive a car like mine with a 24-inch wheel diameter, losing even 2% of the radius, just ½ of an inch of worn rubber, can result in the same 2% change in the accuracy of the speedometer. This relationship can be seen using the equation v=(2πr)/T. If one were to decrease the radius value by 2%, while holding T constant, the magnitude of velocity would also decrease by 2%. The same is true for changing the period; a 2% decrease in T results in a 2% increase in the velocity. So, if one were to decrease r while the computer assumes that it is unchanged, the result would be a larger velocity value than the true value based on the constantly measured T. This means if the speedometer reads 60 mph while assuming r=12 inches, the car would actually be traveling more like 58.8 mph with true r=11.75 inches, based on the same measured value for T. 

Knowing this, the same effect is true if I were to purchase a set of snow tires with a larger radius than my current wheels. If I were to purchase 26-inch diameter wheels with snow tires, the change in actual radius would be on the magnitude of 8.3%. Using the relationship above I can estimate that if my speedometer were to show 60 mph, the car would actually be traveling 8.3% faster, or 65 mph. This inaccuracy could easily result in a speeding ticket.

            So, for those of you trying to track down a new set of tires, go the extra mile and visit a mechanic to have your speedometer adjusted if the diameter of your wheels changes. It might cost more up front, but it could help save you the steeper cost of a speeding ticket in the long run.

 

 

 

 

Sources:

- Attorneys, A. (2017, July 11). How Tread Wear and Tire Pressure Affects Speed. Retrieved October 24, 2020, from https://newyorkspeedingfines.com/tread-wear-tire-pressure-affects-speed/

- Woodford, C. (2020, January 06). How do speedometers work? Retrieved October 24, 2020, from https://www.explainthatstuff.com/how-speedometer-works.html

Squirrel vs. Bird Feeder: Why the Squirrel Always Fails

No squirrels were harmed in the invention of these bird feeders. 

   

 Squirrels get hungry, like any animal, but these creatures are known to gather food from any source they can find. Even if that food is not meant for squirrels, such as birdfeed. That is why some companies invented bird feeders that prevent squirrels from stealing the food through a weighted motor that spins when the weight of a squirrel sets it off, like the one pictured above. The circular motion of their spin is controlled by physics!

    Centrifugal force is one aspect acting on the squirrel that pushes the squirrel away from the center of the feeder. This force is what helps to knock off the squirrel from the feeder as the rotational motion increases. Rhett Allain likes to think of this force as a "fake force" acting in the direction opposite the center of the circle. Whereas centripetal acceleration works to accelerate the squirrel in a circular motion by accelerating towards the center of the circle. Once the centripetal force gets too high, the squirrel is thrown off in a tangential path to the motion of the circle. 

    The motion of the squirrel was studied by Rhett Allain through the use of Tracker. He discovered that the squirrel takes 0.5 s per revolution which helped him to calculate an angular velocity of 12.6 rad/s. The radius of the birdfeed is 0.15 m. He was able to put these values together in order to calculate the centripetal acceleration of the squirrel, which he determined to be 23.7 m/s^2. 

Imagine being such a small creature that is forced to endure such speed and force in order to save the humans the struggle of purchasing more feed for wild birds. 

Image sources:

https://tenor.com/search/spinning-squirrel-proof-bird-feeder-gifs

https://morebirds.com/products/droll-yankees-yankee-flipper-squirrel-proof-bird-feeder-yf

https://www.wired.com/story/how-to-whirl-a-squirrel-off-a-bird-feeder/

Reference:

https://www.wired.com/story/how-to-whirl-a-squirrel-off-a-bird-feeder/

Physics in the COVID-19 World

                                                                                                                                              Jenna Borovinsky

Physics in the COVID-19 World: Reducing chances of COVID-19 infection by a cough cloud in a closed space

https://aip.scitation.org/doi/am-pdf/10.1063/5.0029186

Background:

The authors of this research article are Amit Agrawal and Rajneesh Bhardwaj. Amit Agrawal is a professor in the department of mechanical engineering at the Indian Institute of Technology in Bombay Powai, Mumbai 400076, India. He received his Ph.D. at the University of Delaware in 2002 and received his bachelors in technology at IIT Kanpur in 1996. His co-worker, Rajneesh Bhardwaj is an associate professor in the department of mechanical engineering at the Indian Institute of Technology in Bombay Powai, Mumbai 400076, India. He received his Ph.D. at Columbia University in 2009 and was a postdoctoral fellow at Johns Hopkins University from 2010-12. 

Blog:

While it is wide-spread knowledge that coughing does spread harmful respiratory droplets in an open air of space, and is spread airborne, it is not known the volume of air at which this bacteria spreads. This is particularly important for COVID-19, as this harmful virus is the cause of a worldwide pandemic in which a vaccine has yet to be finalized for. Without a vaccine, a limitation in how far it spreads is the only way to slow the spread of this virus. Further, the impacts on ventilation systems within closed spaces has been studied due to this, and the exact volume of air in which these respiratory droplets spread would be very beneficial in order to know what type of ventilation should be used for a certain sized space. Professor Agrawal and Professor Bhardwaj sought to study the volume of air a cough by someone infected with coronavirus spreads in a closed space, and how much a mask can limit this spread. They also looked at the temperature and relative humidity of the cloud emitted when coughing, which aids in the establishment of a ventilation system to adequately limit the spread. Using literature equations, they derived an equation:

This equation shows that the air’s volume contained in the cloud is only dependent on the spread rate and distance travelled by the cloud, and is independent of the cough’s initial volume and velocity. Utilizing this equation in their study they found that volume in the cloud ultimately increases quadratically with distance. In terms of finding the temperature of the water droplets they used the conservation of energy equation and the specific humidity and then derived the relative humidity form that equation, which resulted in:

In the equation Pa is the partial pressure of air and Pg is the partial pressure of water vapour in saturated mixture at the given temperature. Utilizing this equation they found that the cloud’s temperature lowers monotonically from the exit temperature at the origin to the room temperature. This aids in elucidating how the droplets distribute within the cough cloud. Further, in order to compare the lateral velocity to the front velocity they derived this equation: 

This equation compares lateral velocity as a function of radial coordinate. The data shows that the lateral velocity was not only smaller than the front velocity, but also shows a difference in time. They then compared the time at which the cloud from a cough with someone infected with coronavirus spreads with no mask, a surgical mask and an N95 mask, using the equation they derived:

Utilizing this equation they found that the first 5-8 s after the cough occurs is crucial to stop droplets in air that individuals breathe in. Further, the volume of air infected with virus particles is around 23 times more than that ejected by coughing during this time period. The presence of a mask, even more so with an N-93 mask, significantly decreases this volume and consequently, dramatically lowers the risk of the infection to the others in the room. 

Overall, I found this research article to be very interesting in terms of how prevalent it is to today and how this data will really aid the pandemic we are facing. The research further proves how important a mask is in stopping the spread of COVID-19. It also shows how a mask still does not fully stop the spread of COVID-19 particles emphasizing the need for social distancing along with wearing a mask. The exact quantification in the spread of respiratory droplets will be very beneficial to create suitable ventilation systems. This article shows the power of Physics in having the ability to really slow the spread of the coronavirus. 

Works Cited

Agrawal, Amit, and Rajneesh Bhardwaj. “Reducing Chances of COVID-19 Infection by a 

Cough Cloud in a Closed Space.” Physics of Fluids, vol. 32, no. 10, 2020, p. 101704., 

doi:10.1063/5.0029186. 

News in the world of medical Physics

     In the time of COVID-19,  we have learned a lot about ventilators and their purpose in treating critically ill patients.  As an EMT, medical physics was a topic of interest for me. Many of the most seriously ill patients infected with COVID-19 develop pneumonia and need assistance-breathing. This is done using mechanical ventilators, which pump oxygen into the lungs and then remove the carbon dioxide that they breathe out. 

    Physicists of the DarkSide experiment team at the Gran Sasso National Laboratory in Italy have designed a new, stripped-down mechanical ventilator. Heading the project are two men named Art McDonald and Cristiano Galbiati.  Galbiati is a particle physicist at Princeton University currently working at the Gran Sasso national lab, which is run by Italy's National Institute for Nuclear Physics (INFN).  Working with a team of more than 200 experts, including doctors, engineers and fellow physicists, the new ventilator went from just an idea to FDA approved in just 42 days.  The ventilator is now in full production. These ventilators are designed specifically for COVID-19 patients. The design is simple, cheap, compact and requires only compressed oxygen and a source of electrical power to run.  Galbiati has used his expert research in constructing sensitive instruments for compressed argon and applied it compressed oxygen and nitrogen in a medical instrument.

    Galbiati studied at an Italian university and majored in electronic engineering.  Galbiatis' main research focus is particle physics, specifically dark matter.  Recent observations from his lab have demonstrated that a large fraction of the energy in the universe (25%) is in the form of cold matter that does not clump and does not shine light.  This is called dark matter. Dark matter is one of the fundamental constituents of the universe and has never been directly observed.  He is currently exploring new ideas on direct dark Matter detection using argon and xenon as targets.

Sources:

1) Biron, Lauren. “FDA Approves Ventilator Designed by Particle Physics Community.” Princeton University, The Trustees of Princeton University, 2020, www.princeton.edu/news/2020/05/05/fda-approves-ventilator-designed-particle-physics-community.

2)Fuller-Wright, Liz. “Particle Physicists Design Simplified Ventilator for COVID-19 Patients.” Princeton University, The Trustees of Princeton University, 2020, www.princeton.edu/news/2020/04/09/particle-physicists-design-simplified-ventilator-covid-19-patients.

The compatibility of MRIs and cochlear implants

By Mandy Ennis

There is very interesting research being done currently and in recent years on the subject of MRIs, a commonly used imaging tool that provides exceptional spatial resolution, and their use on individuals with cochlear implants. Given that MRI stands for Magnetic Resonance Imaging, it comes as no surprise that MRIs relate directly to the study of physics through the use of magnetism. Although magnetism is not a subject we have discussed thoroughly in this class, it is still relevant given the emphasis of this class on force and related physical variables. 

Sonnenberg et al. (2002) conducted research on the compatibility of MRIs and cochlear implants, devices that use a magnetic field between the two main components of the implant, the external transmitter on the scalp and the internal stimulator-receiver, which is surgically implanted into the skull and cochlea, to keep the device in place and functioning properly. Given that MRIs use magnetism to visualize internal structures within the body, it is important to understand the interaction between cochlear implants and MRIs and their respective magnetic forces to determine their safety when used in combination. This research by Sonnenberg et al. (2002) examined the magnitude of the magnetic force that is able to be exerted on the cochlear implant by the MRI without causing injury to the patient; such potential injury could include skull fracturing and pressure on the brain, as well as dysfunction of the cochlear implant. For example, Bawazeer et al. (2019) reported an occurrence of demagnetization of the cochlear implant, which necessitated removal and reimplantation, and another occurrence of  “considerable pain” in two different patients with cochlear implants that underwent MRIs. Using various materials to attach the stimulator-receiver, as well as varying skull thicknesses, Sonnenburg et al. (2002) measured the magnitude of magnetic force exerted by the MRI on the implant and the displacement of the internal stimulator that would fracture the skull. Compared to the acceptable “safe” magnetic force that is typically experienced by the wearer of a cochlear implant without causing injury, they found that in general, MRIs should be safe for use in individuals with cochlear implants; however, there is still precaution regarding compatibility of cochlear implants and the use of MRIs (“Johns Hopkins Cochlear Implants MRI Protocol”). Many factors influence the safety of undergoing an MRI with a cochlear implant, such as the length of time since the implantation (since the skull should ideally heal fully before undergoing any magnetic imaging) and the thickness of the patient’s skull.  

A Google search of the name of the author (Robert E. Sonnenberg, MD) revealed that Dr. Sonnenburg is an ENT-otolaryngologist in Wisconsin. I wasn’t able to determine his undergraduate education, but he received his MD from the Medical College of Wisconsin in 2000 and completed his internship and residency at the University of North Carolina, Chapel Hill (​U.S. News & World Report​ ). Although it is not known whether Dr. Sonnenburg has a background in the field of physics, this research directly relates to some of the topics that we have addressed in our class, as we have discussed the force that can be applied to the head without causing injury. In general, our class has also focused on forces and displacement, which is directly related to this research. 

Sources: 

1. Bawazeer, Naif, et al. “Magnetic Resonance Imaging after Cochlear Implants.” ​Journal of Otology​ , Chinese PLA General Hospital, Mar. 2019, www.ncbi.nlm.nih.gov/pmc/articles/PMC6424707/.

2. “Dr. Robert E. Sonnenburg Jr.” ​U.S. News & World Report​ , U.S. News & World Report, health.usnews.com/doctors/robert-sonnenburg-jr-228323.

3. “Johns Hopkins Cochlear Implant MRI Protocol.” ​Johns Hopkins Medicine​ , Johns Hopkins Hospital, 10 Dec. 2018, www.hopkinsmedicine.org/otolaryngology/specialty_areas/listencenter/resources/mris-at-hopkins .html.

Geese in Flight

    I could say Colgate is known for many things. The academics are challenging, the professors are top-notch, and we have some of the best sports teams in the Patriot League. I could also say with certainty that Colgate is one of the most beautiful campuses I have ever seen. One of our gems is Taylor Lake: a true stunner, but one that I would not recommend a swim in.

    I walked by it the other day on my way to Physics lecture, and I noticed just how quiet it can be around this time of the year. The characteristic honking of Hamilton's noisy seasonal geese population was missing. It's always sad to see them go, even if they have been known to attack the curious first year. Their disappearance is a grim reminder of the months of snow and ice to come. As I was imagining all of the bruises and bumps certain to join me on my walks around campus this winter, I heard a single honk in the distance. Looking up, I noticed a group of about twelve geese gliding in their famous V-shaped flight pattern. I could not help but think that there must be some sort of physics involved in this flight, and as it turns out, there is.

    During the solo flight of any bird, there are four main forces at play. On the x-axis, a bird must overcome the drag force due to air resistance by using its wings to apply some force, or thrust, forward. At the same time, the bird must counteract the force of gravity through a lift force that is provided by rising air beneath its wings. Balancing all of these forces to retain straight flight consumes a great deal of energy quickly. One way to reduce the amount of energy lost during flight can be observed in the geese's V-shaped formation.

    When a bird flaps its wings' downward, the displacement of particles toward the ground causes a the formation of a vortex of air directly behind its body. This movement of air can also be observed trailing the wings of airplanes, as seen in the diagram above, but just at a much larger scale. The force of the wings displacing the air downward causes air to rise in the column adjacent to it. The V-shaped formation of the geese's flight allows one bird behind another to align itself with this increased lift force. Experiencing the "upwash" during a flap of the wings creates an instant in which the magnitude of the lift force exceeds the force of gravity by a larger margin than before. This results in a momentary increase in altitude. Over long periods of time, this sensation reduces the amount of energy exerted in flight and can allow a flock of geese to reach their destination with fewer stops.

Further information can be found here: https://www.youtube/come/watch?v=pB6XSixrCC8

Also here: https://www.nationalgeographic.com/science/phenomena/2014/01/15/birds-that-fly-in-a-v-formation-use-an-amazing-trick/

Ronaldo is Jumping to New Heights

  Soccer has always been a passion of mine. As such, I found it fitting to discuss the physics behind one of the most famous soccer goals of all time. Being able to head the ball is an essential part of being able to play soccer. Heading the ball correctly, and in the right direction, can be the difference between a win and a loss for any team. 

Cristiano Ronaldo, perhaps one of the best soccer players in the history of the sport, is renowned for his ability to jump to extreme heights in order to score goals. In fact, his jumps have been recorded as being higher than the average NBA basketball player. In the particular instance shown in the picture below, Ronaldo jumped to reach a height of 2.6 meters (over 8.5 feet above the ground!) in order to head the ball into the back of the net. Ronaldo is 188 cm (6’2”), meaning that he jumped 0.72 meters (almost 2.5 feet) in 0.75 seconds in order to reach the ball. 

 

Using the equation:

, we can determine that Ronaldo’s initial vertical velocity was 4.64 m/s!

Ronaldo’s ability to perform such a feat was measured during biomechanic tests on the forward at the University of Chichester in 2011. They determined that the force Ronaldo used to push off was almost 5g – similar to what an astronaut experiences during take-off. Because Ronaldo jumps so high, he appears to be airborne for much longer than less athletic players. Dr. Neal Smith, from the University of Chichester, explained that at the peak of his jump, Ronaldo tucks his feet up, giving him a boost which slows down his descent. That is why it looks like he is hanging in the air. But what accounts for Ronaldo’s high jumps? Is he defying the laws of physics? It turns out that having powerful thigh and upper body muscles are essential for this kind of leap. Cristiano Ronaldo spends hours in the gym each day, training his muscles to maintain his power (the circumference of his thighs is 62cm!). His muscle strength, in addition to his low body fat, may account for his ability to jump so high compared to other players.

Below is a link to the video of researchers at the University of Chichester performing research on Cristiano Ronaldo and how he is able to reach such extreme heights!

Link to video of biophysical tests being performed on Cristiano Ronaldo:

https://www.dailymail.co.uk/sport/football/article-2278671/Cristiano-Ronaldo-Why-Real-Madrid-player-jump-higher-else.html#v-2165166084001

      The Pittsburgh Steelers did a tour de force in the 2020 NFL draft by acquiring Chase Claypool, a Canadian wide receiver who played at Notre Dame. As a rookie, Claypool blasted 3 touchdowns on the Philadelphia Eagles, and since then, all eyes are on this future star. On October 18th against the Cleveland Browns, Claypool did not deceive, totaling 74 receiving yards. One of his four catches was a 36 yards reception putting the Steelers in a really good position to score. The timing between the receiver and his QB Ben Roethlisberger was impeccable. Although players do not think about the physics behind their actions, many concepts that we have studied in class can be applied to that 36 yards reception.

https://www.youtube.com/watch?v=L0-PVh2zVTQ

     First, by analyzing the video and using the official NFL field dimensions, I was able to approximate the position of the ball (position of the Qb), and the position of Claypool at the moment of the throw which I considered to be the initial time (t=0 seconds). With the video, I also found the final position of both the ball and Claypool, in addition to the air time of the ball using a stop watch: 2.2 seconds. Although the WR route was an "out'n'go", which means that the receiver ran towards the sideline before cutting upfield, the QB did not throw the ball until Claypool started running upfield as he needed to assess if the defender was eliminated. Thus, Claypool's run while the ball is in the air is approximately vertical.

      

  After finding the different position and distance components of the receiver and the ball at both t=0 and t=2.2s (t final found using a stop watch), I used kinematics to find the x and y components of the initial velocity of the ball. This allowed me to find both the angle and the initial velocity of the throw. The orientation of the throw and the average speed of the receiver were also found as they are part of the timing of the play.

     The conclusion of this play's analysis is at follows: Ben Roethlisberger threw the ball when Chase Claypool was on the 21 yard line. He threw it with an angle of 28.4 degrees above the horizontal with an initial velocity of 22.7 m/s. Roethlisberger's body was oriented 56.2 degrees North to West, and the ball reached a height of about 8m above the ground. On his side, Claypool ran at an average speed of 5.6m/s vertically while the ball was in the air. Many assumptions were made in the calculations. I assumed that there was no air friction, disregarded the arm length of both players, rounded both players' heights to be the same as they were very similar, an assumed that all NFL football fields have the exact same dimensions. Imprecision in the positions' approximation are also to be considered.

       It is truly interesting to see how a single football throw combines so many physics concepts and it is even more outstanding to realize that the human body is capable of doing such calculations in the span of milliseconds. 

Frictional Force in Rock Climbing

Rock climbing is one of my favorite activities, and I wanted to explore how physics is used throughout different aspects of climbing. 

Many aspects of climbing technique and of climbing gear are designed to increase frictional force. For example, climbers put chalk on their hands to decrease sweat and increase the coefficient of static friction of their hands. Climbing shoes are made of soft rubber designed to mold to the features in the rock, which also increases the coefficient of static friction because more parts of the shoes are in contact with a rougher surface. This increased friction helps the climber to stay on the wall because there is more force opposing the motion of them slipping off. 

Besides the aspects of the climber that are directly in contact with the rock, the rope systems are also designed to increase friction so that if a climber falls, they fall slower and a shorter distance. According to the work-energy principle, the more work done by nonconservative forces—friction in this case—the less energy that gets converted from the initial gravitational potential energy into kinetic energy and into final gravitational potential energy. 

Below is a picture of a common anchor used at the top of climb to hold the rope. Using two carabiners in the anchor allows the rope to stay in place if one of the carabiners fails, and it also doubles the frictional force of the carabiners on the rope. This frictional force opposes the motion of the climber if they fall and, therefore, opposes the force of gravity; an increase in this upward frictional force means that the climber falls less far.

In addition to using equipment that increases frictional force, the belayer, the person responsible for taking slack out of the rope and catching the climber’s falls, can position their end of the rope at an angle that can increase the y-component of the frictional force of the belay device on the rope. This y-component is important because it is parallel to the force of gravity. If the climber falls, and the rope attached to them moves downward, the end of the rope that the belayer is holding will move upward. The frictional force in the belay setup opposes this upward motion. Positioning the belayer’s end of the rope with as small of an angle between the belay device and the rope allows the y-component of the frictional force from the belay device on the rope to be as large as possible so that the belayer’s end of the rope moves upward as little as possible. This increase in frictional force of the belay device on the rope increases the work done by friction for the entire system, thereby decreasing the velocity of the climber and the climber's change in gravitational potential energy.