Bowdoin Science Journal

Math and Physics

Coronal Bright Points As a Solution to the Sun’s Coronal Heating Problem

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As the star closest to the planet we call home, the Sun is heavily researched for its impact on the Earth and as a model for the dynamics of stars further out. One of the most prominent and vexing questions in modern helio science is the coronal heating problem. Our common sense and everyday experiences tells us that as we move further from an isolated source of heat, temperature drops. However, although the average effective temperature of the photosphere (visible surface of the sun) is 5800K, the outer atmosphere of the Sun, the corona, can reach up to 107K during eruptive solar flares (Sigalotti 2023). This perplexing temperature transition has initiated many investigations into mechanisms and different phenomena on the surface of the sun that could potentially solve the coronal heating problems. Not only will solving this problem help us understand the processes on our own Sun – and therefore better predict space weather which is crucial to power grids and satellite communication on Earth – but it will also give us more comprehension on stars beyond our solar system as we observe the same phenomenon on other stars.

Figure (1): Layers of the sun with names and corresponding temperatures. Exact temperatures of each layer may differ slightly depending on sources as well as methods of measuring temporal diagnostics. However, there is a clear and drastic transition between a low temperature in the Chromosphere and Photosphere to a high temperature in the Corona. (Helmenstine, Anne, 2024)

A promising theory explaining this phenomenon involves a mechanism called magnetic reconnection. This process converts magnetic energy into thermal energy when oppositely charged magnetic field lines break and reconnect on the surface of the sun. This is also the process that causes solar flares in active regions (AGs) of the sun. Additionally, solar activity outside of active regions is dominated by coronal bright points (CBPs). These hot small-scale loops can be the sight of “small-scaled filament eruptions”, much like a solar flare, and “coronal jets” which can all be possible answers to the coronal heating problem (Nóbrega-Siverio, 2023). Because of their long lifespan (hours to days) and their ubiquitous numbers on the Sun’s atmosphere, creating more realistic models of coronal bright points can provide significant insight into the heating of the solar corona (Madjarska, 2019).  Their numbers stay high even during solar minimum (part of the solar cycle when there are less solar flares). Last year, Dr. Daniel Nóbrega-Siverio and his collaborators created a 3D numerical model of CBPs that is consistent with direct observations made by the Solar Dynamics Observatory (SDO) and the Swedish 1-m Solar Telescope (SST) using the Bifrost code. The Bifrost code is a modeling code that solves partial differential equations describing 3D radiation dynamics of magnetic fields which can be used to model solar flare mechanisms on the surface of the Sun (Mikołaj Szydlarskiaa, Vegard Eideb). Dr. Nóbrega-Siverio describes these promising comparisons between real life observations using space telescopes and his model in his paper. 

Starting with a 3D model of a nullpoint magnetic topology (the base of a CBP model that starts at a single spot where the net magnetic field strength is zero), an investigation into the heating per unit mass due to different mechanisms is conducted at three different heights above the sun’s visible surface. The simulation reveals that CBP loops are mainly heated by a continuous convection in the lower solar atmosphere. This is a major difference from previous 2D models of CBPs as these mechanisms can only be visualized in 3D. Additionally, results from this experiment are consistent with values from previous numerical experiments. In other words, Dr. Nóbrega-Siverio and his colleague’s work shows that CBPs have energy levels deemed necessary for the heating of the quiet Sun corona. Subsequently, this 3D model was able to provide a more complex understanding of coronal bright points than its 2D predecessor. 

The experiment also brought in comparisons to direct observations of a CBP made by SDO and SST on July 1st, 2022. These comparisons maintained the accuracy of the model by showing that both the direct observations and model showed a pattern of long H fibrils. H, or hydrogen alpha lines, which is a way to trace ionized hydrogen and a primary method to observe the sun as well as other stars. Additionally, a possible indicator of chromospheric heating, an intense brightening occurred at the base of the fibrils in both the simulation and the direct observations. Both of these realistic features of the simulation are good indicators of the model’s accuracy to the evolution and heating of CBPs (Nóbrega-Siverio, 2023).

Figure (2): Fig (c) shows fibrils of an observed CBP from the SST in the H wavelength. The H wavelength shows the pattern of ionized hydrogen in a CBP. These patterns are present in both the direct observation as well as the 3D model, giving confidence that the new model is doing what we expect to see in real life. (Nóbrega-Siverio, 2023)

Accurate models of solar phenomena are the foundations of understanding our Sun. Regarding puzzling questions such as the coronal heating problem, accurate models of the evolution and mechanisms of solar flares, coronal holes, and, of course, CBPs much like the one devised by Dr. Daniel Nóbrega-Siverio is crucial. With the knowledge that these more and more complete models give us, we are steps closer to understanding the causes of solar coronal heating. Solving this problem will aid us in our prediction of space weather that has an impact on power grids, satellite performance, GPS, and on ground communication to name a few and in the long run, help negate and prepare for negative effects of solar storms aimed at the Earth.

References:

Nóbrega-Siverio et al 2023 ApJL 958 L38. https://doi.org/10.3847/2041-8213/ad0df0

Helmenstein, Anne. “Layers of the Sun – Diagrams and Facts.” Science Notes. 14 February, 2024, https://sciencenotes.org/layers-of-the-sun-diagram-and-facts/#google_vignette. Date Accessed April 13, 2024. 

Leonardo Di G. Sigalotti, Fidel Cruz; Unveiling the mystery of solar-coronal heating. Physics Today 1 April 2023; 76 (4): 34–40. https://doi.org/10.1063/PT.3.5217

Madjarska, M.S. Coronal bright points. Living Rev Sol Phys 16, 2 (2019). https://doi.org/10.1007/s41116-019-0018-8

Mikołaj Szydlarskiaa, Vegard Eideb. “Stellar Atmosphere Simulation code Bifrost on Intel Xeon Phi Knights Landing.” Prace. https://prace-ri.eu/wp-content/uploads/WP233.pdf. Date Accessed April 13, 2024. 

Cover image taken by Nathan Bukowski-Thall, Bowdoin Class of 2026 during the April 2024 total solar eclipse

Navigating the Unseen: Wireless Muon Technology Revolutionizes Indoor Positioning and Beyond

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Cosmic rays have captivated scientists due to their enigmatic origins, imperceptibility, and natural abundance. Originating from celestial bodies ranging in distances from as close as our sun to as far as distant galaxies, these particles bombard our Earth at rates close to the speed of light. While these particles are responsible for the aurora borealis displays in the arctic, for the most part they go unnoticed and have been mainly researched in the context of astronomy and astrophysics (Howell 2018). However, recent development in muon tomography and research from Professor Hiroyuki Tanaka’s research group from the University of Tokyo has developed a wireless muometric navigation system (MuWNS) capable of using muons to create an indoor positioning system (Tanaka 2022).

Formation of muons from particle showers (Vlasov, 2023).

Muons are natural subatomic particles that are created from cosmic rays interacting with atoms in the atmosphere. With their mass around 207 times that of electrons, muons are capable of penetrating solid materials and water (Gururaj 2023). This unique property of muons has allowed for their use in mapping the interiors of hard-to-access places such as volcanoes, tropical storm cells, and even Egyptian pyramids (Morishima, 2017). Professor Tanaka’s team has now focused on improving the currently limited GPS system with a wireless muon detection system capable of navigation in places where radio waves used in GPS can not reach. This makes it an ideal technology for underground and underwater navigation, natural disaster relief, exploration of caves in planets, and much more. 

While the initial principle behind MuWNS involves the precise measurement of the timing and direction of cosmic-ray-generated muons through reference detectors, Professor Tanaka’s team had issues with the synchronization of time between the reference and receiver detectors (Tanaka, 2022). This precise time synchronization issue was displayed in their 2022 MuWNS prototype that had a navigation accuracy between 2-14 m, which Professor Tanaka claims is “far from the level required for the practical indoor navigation applications.” In a more recent article published in September 2023, Professor Tanaka has shifted his focus from using the timing of muons to measuring the directional vectors of incoming muons. Thus, instead of using the time of muon travel between the reference and receiver detectors for navigation, the next generation vector muPS (muometric positioning system) uses the angles of incoming muons through the reference and receiver detectors to locate the detector’s positioning. In essence, matching the angles of muons entering the two detectors confirms the same muon event. By identifying the same muon event, the angle and path of the muon is then used to determine the position of the receiver detector without relying on timing mechanisms. This approach minimizes the effects of time synchronization resulting in what he predicts as centimeter-level accuracy (Tanaka 2023). This new development has been greeted with excitement, earning Professor Tanaka’s team a spot in Time Magazine’s “The Best Inventions Of 2023” (Stokel-Walker 2023).

This image is from Professor Tanaka’s article on wireless muometric navigation systems. Image A depicts underwater navigation with floating reference detectors and muons marked as red lines. Image B depicts underground navigation using surface reference detectors to control the receiver. (Tanaka, 2022).

After being intrigued by Professor Tanaka’s work published in Nature (Tanaka 2023), I reached out to him asking a few questions for this article. The first question I asked was about the presence of muons and whether muon tomography could work on other celestial bodies. His response highlighted that muons are in fact generated in dust deposits on top of the surface of the Moon and Mars. Specifically, Professor Tanaka discussed how muons could be used to explore caves within the Moon. This would involve deploying a muPS navigating robot that uses muons generated in the regolith for navigation underground. This could allow us to explore hard to examine places on other planets without the physical presence of human exploration.

The second question involves the application of muPS within cell phones. Tanaka explains that our phones currently have a GPS receiver inside of them, allowing us to track their location when they are lost. However, if the cellphone is lost in an elevator, basement, cave, or room that has limited GPS signals, muPS could locate the phone instead. With 6.92 billion smartphone users worldwide, this application could be useful in natural disasters where individuals may be trapped under rubble and GPS signals cannot locate their phones (Zippia 2023). 

Finally, I asked Professor Tanaka what made him excited about muPS. He responded by discussing the current limitations with our present indoor/underground navigation systems and how they all rely on laser, sound, or radio waves to guide them through obstacles. This method he claims is not technically navigation because it does not provide coordinate information and thus is un-programmable. Tanaka states that “muPS is [the] only technique that provides the coordinate information besides GPS” and it can be used in locations where GPS is unavailable. 

In future technology, muon-based positioning systems may provide the opportunity to open new navigational and observational possibilities, propelling us into a world of new discoveries and exploration on Earth and beyond. 

 

Work Cited

  1. Gururaj, T. (2023, June 16). World’s first cosmic-ray GPS can detect underground movement. Interesting Engineering. https://interestingengineering.com/innovation/cosmic-ray-gps-underground-movement-disaster-management-muons 
  2. Howell, E. (2018, May 11). What are cosmic rays?. Space.com. https://www.space.com/32644-cosmic-rays.html 
  3. Morishima, K., Kuno, M., Nishio, A. et al. (2017). Discovery of a big void in Khufu’s Pyramid by observation of cosmic-ray muons. Nature 552, 386–390.. https://doi.org/10.1038/nature24647
  4. Stokel-Walker, C. (2023, October 24). Muon Positioning System: The 200 best inventions of 2023. Time. https://time.com/collection/best-inventions-2023/6326412/muon-positioning-system/ 
  5. Tanaka, H.K.M. Wireless muometric navigation system. Sci Rep 12, 10114 (2022). https://doi.org/10.1038/s41598-022-13280-4
  6. Tanaka, H.K.M. Muometric positioning system (muPS) utilizing direction vectors of cosmic-ray muons for wireless indoor navigation at a centimeter-level accuracy. Sci Rep 13, 15272 (2023). https://doi.org/10.1038/s41598-023-41910-y
  7. Vlasov, A. (2023, April 14). Muon Imaging: How Cosmic Rays help us see inside pyramids and volcanoes. IAEA. https://www.iaea.org/newscenter/news/muon-imaging-how-cosmic-rays-help-us-see-inside-pyramids-and-volcanoes 
  8. Zippia. 20 Vital Smartphone Usage Statistics [2023]: Facts, Data, and Trends On Mobile Use In The U.S. Zippia.com. Apr. 3, 2023, https://www.zippia.com/advice/smartphone-usage-statistics/

A Swing and a Miss

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In July 2023, a revolutionary preprint paper was published. Researchers at the Quantum Energy Research Center in Seoul, South Korea claimed to have synthesized a material, LK-99, that is a superconductor at room temperature (TC ≥ 400 K) and ambient pressure. They believed that this discovery would be a “brand-new historical event that opens a new era for humankind” (Lee, 2023). Given that all superconductors developed so far operate only under very high pressures or very low temperatures, this indeed would have been a game changer. However, as of November 2023, repeated unsuccessful attempts to reproduce the superconductive property in this material have added this study to a growing list of apocryphal claims in scientific literature.

What is a superconductor?

A superconductor is a material that allows current to flow through it without any resistance. For example, think of a toaster. The exposed wires in a toaster are typically made of a nickel-chromium alloy, which has a high resistance. As the electrons flow through the wires, they collide with the atoms of the wires and generate heat, enough to toast your bread. Superconductors, however, allow electricity to pass through without any resistance. A superconductor toaster then, would not generate any heat and leave the bread cold.

Naturally, a straightforward method to determine if a material has superconductive properties is by measuring whether the resistance of a current flowing through it falls to zero. This phenomenon usually occurs at a specific temperature known as the “critical temperature”, which varies for different materials.

Another unique property of superconductors is quantum levitation. The Meissner effect causes a superconductor to expel incoming magnetic fields by producing small currents on the surface of the material. The magnetic force is strong enough to counter gravity and push the superconductor up. However, in type-1 superconductors, the complete lack of magnetic fields inside the material would lead to an unstable wobbly floating if it were placed on top of a flat magnet. In type-II superconductors, flux tubes or tunnels can form through the superconductor and effectively lock the material in place above a magnet. This levitation, combining the principles of the Meissner effect and flux pinning, creates what can be described as a seemingly magical phenomenon, where a superconductor floats effortlessly above a magnetic source. (Hellman et al., 1988) (Murakami et al., 2018).

Credit: Simran Buttar

Credit: Mai-Linh Doan/Wikimedia Commons

Debunking LK-99

LK-99 is a polycrystalline structure made of lead, oxygen, and phosphorus and is infused with copper. The report on LK-99 indicated a sharp decrease in resistivity at around 104 C, the supposed critical temperature for that material. Jain explains this apparent superconductive effect in his preprint to be the result of a phase transition of copper (I) sulfide at around 104 C, which caused the sudden change in electrical resistivity (Jain, 2023). He explains that this sudden drop likely led the Korean researchers to believe that they had reached the critical temperature.

To further disqualify the study, researchers at Peking University observed a “half-levitation”, a phenomenon that exhibits within ferromagnetic insulators but is not the kind of diamagnetic levitation resulting from the Meissner effect in superconductors. This was observed in videos of the LK-99 made in Korea as well as in the Chinese teams’ recreation of the material and testing of its Meissner effect (Guo et al., 2023).

Other studies have shown that LK-99 is not a feasible superconductor through theoretical methods (Jiang et al., 2023), while other studies have recreated the material but not the superconductive properties at room temperatures (Puphal et al., 2023). The accumulating evidence places LK-99 firmly in the realm of improbable scientific breakthroughs, casting doubt on its viability as a room-temperature superconductor.

Behind the Controversy

The drama began with Korea University professor Young-Wan Kwon’s rapid publishment of the significant paper. Shortly after, the rest of the team published a similar paper, notably without Kwon as a co-author. There was reportedly a clash between Kwon and the author of the second paper, Suk-Bae Lee. One popular rumor explaining the hurried first paper is that Kwon was afraid he would not receive the Nobel Prize, an award that can only be shared by up to three individuals.

Shortly after the publication, Kwon was confirmed to have been removed from the Quantum Energy Research Centre. Although much of the story is shrouded in mystery, an investigation into the case was begun by Korea University and is expected to shed light on the details of the case. The results of this inquiry are expected to conclude by early next year and will hopefully unravel the complexities of this controversy.

Superconductors now and in the future

Superconductors have already found significant applications in today’s world, particularly in the field of medical technology. Many MRI machines, for example, depend on superconducting wires to create the strong magnetic fields necessary for producing detailed body scans used in medical diagnostics and imaging (Parizh et al., 2017, Manso Jimeno et al., 2023). Similarly, superconductors are used in the Superconducting Quantum Interference Device (SQUID), which allows for extremely sensitive detection of magnetic fields, thus allowing for precise imaging of the brain. Such advancements could revolutionize neuroscience studies, offering insights into brain function and aiding in the development of neurological treatments (Fagaly, 2006).

Superconductors can also be found in transportation systems such as the Maglev, magnetically levitating trains that can travel over 300 mph. Materials with the touted properties of LK-99 could potentially eliminate the need for expensive and environmentally taxing cryogenic cooling systems currently necessary for such levitating trains (Biswas & Biswas, 2023) Generally, reducing the cost and increasing the efficiency of producing superconductors will accelerate advancements in numerous other technologies, like fusion energy and particle colliders, that rely on high-temperature superconductors. (Castelvecchi, 2023).

The enthusiasm surrounding groundbreaking technologies such as room-temperature superconductors is indeed thrilling, but it appears LK-99 won’t be at the forefront of this innovation. As the scientific community continues to explore alternative materials and methods, the dream of a room-temperature superconductor remains an elusive goal. In the meantime, the case of LK-99 serves as a valuable lesson in the cautious optimism required in technological breakthroughs.

 

References 

  1. Bardeen, J., Cooper, L. N., & Schrieffer, J. R. (1957). Theory of Superconductivity. Physical Review, 108(5), 1175–1204. https://doi.org/10.1103/PhysRev.108.1175
  2. Biswas, S., & Biswas, S. (2023). Current Status and Potential Uses of LK-99, Room Temperature Semi-Conductor: An Update and Review. SSRN Electronic Journal. https://doi.org/10.2139/ssrn.4553146
  3. Castelvecchi, D. (2023). How would room-temperature superconductors change science? Nature, 621(7977), 18-19. https://doi.org/10.1038/d41586-023-02681-8
  4. Dasenbrock-Gammon, N., Snider, E., McBride, R., Pasan, H., Durkee, D., Khalvashi-Sutter, N., Munasinghe, S., Dissanayake, S. E., Lawler, K. V., Salamat, A., & Dias, R. P. (2023). RETRACTED ARTICLE: Evidence of near-ambient superconductivity in a N-doped lutetium hydride. Nature, 615(7951), Article 7951. https://doi.org/10.1038/s41586-023-05742-0
  5. Fagaly, R. L. (2006). Superconducting quantum interference device instruments and applications. Review of Scientific Instruments, 77(10), 101101. https://doi.org/10.1063/1.2354545
  6. Guo, K., Li, Y. & Jia, S. Ferromagnetic half levitation of LK-99-like synthetic samples. China Phys. Mech. Astron. 66, 107411 (2023). https://doi.org/10.1007/s11433-023-2201-9
  7. Hellman, F., Gyorgy, E. M., Johnson, D. W., O’Bryan, H. M., & Sherwood, R. C. (1988). Levitation of a magnet over a flat type II superconductor. Journal of Applied Physics, 63(2), 447-450. https://doi.org/10.1063/1.340262
  8. Jain, P. K. (2023). Superionic phase transition of copper(I) sulfide and its implication for purported superconductivity of LK-99. The Journal of Physical Chemistry C, 127(37), 18253-18255. https://doi.org/10.1021/acs.jpcc.3c05684
  9. Jiang, Y., Lee, S. B., Herzog-Arbeitman, J., Yu, J., Feng, X., Hu, H., Călugăru, D., Brodale, P. S., Gormley, E. L., Vergniory, M. G., Felser, C., Blanco-Canosa, S., Hendon, C. H., Schoop, L. M., & Bernevig, B. A. (2023, August 9). Pb$_9$Cu(PO$_4$)$_6$(OH)$_2$: Phonon bands, Localized Flat Band Magnetism, Models, and Chemical Analysis. arXiv.Org. https://arxiv.org/abs/2308.05143v2
  10. Lee, S., Kim, J.-H., & Kwon, Y.-W. (2023). Preprint at https://arxiv.org/abs/2307.12008.
  11. Lee, S. et al. (2023). Preprint at https://arxiv.org/abs/2307.12037.
  12. Lundy, D. R., Swartzendruber, L. J., & Bennett, L. H. (1989). A Brief Review of Recent Superconductivity Research at NIST. Journal of Research of the National Institute of Standards and Technology, 94(3), 147–178. https://doi.org/10.6028/jres.094.018
  13. Manso Jimeno, M., Vaughan, J. T., & Geethanath, S. (2023). Superconducting magnet designs and MRI accessibility: A review. NMR in Biomedicine, 36(9), e4921. https://doi.org/10.1002/nbm.4921
  14. Murakami, M., Miryala, M., & Nagashima, K. (2018). Superconducting Levitation. In Wiley Encyclopedia of Electrical and Electronics Engineering (pp. 1-11). John Wiley & Sons, Ltd. https://doi.org/10.1002/047134608X.W1326.pub2
  15. Parizh, M., Lvovsky, Y., & Sumption, M. (2017). Conductors for commercial MRI magnets beyond NbTi: Requirements and challenges. Superconductor Science and Technology, 30(1), 014007. https://doi.org/10.1088/0953-2048/30/1/014007
  16. Puphal, P., Akbar, M. Y. P., Hepting, M., Goering, E., Isobe, M., Nugroho, A. A., & Keimer, B. (2023, August 11). Single crystal synthesis, structure, and magnetism of Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O. arXiv.Org. https://doi.org/10.1063/5.0172755
  17. Wang, H., Xu, X., Ni, D., Walker, D., Li, J., Cava, R. J., & Xie, W. (2023). Impersonating a Superconductor: High-Pressure BaCoO3, an Insulating Ferromagnet. Journal of the American Chemical Society, 145(39), 21203-21206. https://doi.org/10.1021/jacs.3c08726
  18. “Quantum Levitation Is Cool But How Does It Really Work?” (2020, July 25). https://www.secretsofuniverse.in/quantum-levitation/
  19. Hull, J. R., & Murakami, M. (2004). Applications of bulk high-temperature Superconductors. Proceedings of the IEEE, 92(10), 1705-1718. doi: 10.1109/JPROC.2004.833796

Caution in STEM: Inhibition, Intuition, and Counterintuitive Reasoning

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Imagine you’re on a 1950s game show. The host presents three doors and lays out the rules: Behind one door is a car, and behind the other two are goats. After you choose a door, the host, knowing what’s behind each door, opens one of the remaining two doors, revealing a goat. You have the opportunity to switch. Do you?

This is, of course, the infamous Monty Hall problem. Assuming you prefer the car over the goat, the answer is to always switch, since it will give you double the probability—⅔ rather than ⅓—of winning the car. Here’s an explanation that goes through each possible case (Table 1):

Table 1: Possible outcomes for staying and switching in the Monty Hall problem (Saenen et al., 2018)

If you got it wrong, you’re not alone—between 79% and 87% of adults get it wrong, too (Saenen et al., 2018). But what is behind this phenomenon? Solving unintuitive problems like the Monty Hall problem is thought to require the inhibition of misleading information, such as from prior knowledge or false cues (Dumontheil et al., 2022; Saenen et al., 2018). However, a 2018 study by Brookman-Byrne et al. and a 2022 study by Dumontheil et al. shine a new, more nuanced light on the connection between inhibitory control and (counter)intuition.

Both studies had British schoolchildren aged 11-15 undergo a volley of tests assessing their response inhibition (the ability to manage and filter out conflicting information), semantic inhibition (the ability to suppress responses driven by impulse ), vocabulary, reasoning, and working memory. Researchers then had participants complete a set of intuitive (control) and counterintuitive math and science problems. Dumontheil et al. (2022) measured neural activity using fMRI (functional Magnetic Resonance Imaging, an imaging technique which measures blood-oxygen levels to determine which parts of the brain are active) throughout.

Unsurprisingly, researchers consistently found that participants were more accurate and faster in solving intuitive problems than counterintuitive problems. Furthermore, in counterintuitive reasoning, response inhibition predicted response times, whereas semantic inhibition predicted accuracy. Interestingly, however, the only predictors of counterintuitive reasoning ability found in both studies were a more extensive vocabulary and increased age, both of which also predicted response inhibition (Brookman-Byrne et al., 2018; Dumontheil et al., 2022). Given these unexpected findings, neuroimaging results by Dumontheil et al. (2022) were necessary to provide some insight into what goes on in participants’ brains. 

Figure 1: Brain regions showing greater activation for (A) counterintuitive versus control (intuitive) problems, (C) response inhibition versus no response inhibition, and (D) semantic inhibition versus no semantic inhibition (Dumontheil et al., 2022). 

Figure 2: A comparison between areas showing increased activation during counterintuitive reasoning and (A) complex inhibition behavior, and (B) interference control behavior (Dumontheil et al., 2022). 

Since the overlap is limited in Figure 2, researchers concluded that the relationship between inhibitory control and counterintuitive problem solving was not direct (Dumontheil et al., 2022). They posit that the role of inhibition in counterintuitive reasoning may be limited to specific types of inhibition. In particular, semantic inhibition might be a better explanation than just response inhibition (Dumontheil et al., 2022). 

Neurosynth (an fMRI image database) also associates areas activated during counterintuitive reasoning with “working memory,” “calculation,” “symbolic,” “attention,” “visually,” and “spatial,” suggesting that inhibition is not the only factor at play (Dumontheil et al., 2022). They highlight that two areas known as the intraparietal sulcus (IPS) and Brodmann area 7 (BA 7)—which together are responsible for visuo-spatial attention—show increased activation during counterintuitive reasoning, response inhibition, and semantic inhibition (Dumontheil et al., 2022). Hence, they also suggest that visuo-spatial attention may be another factor in counterintuitive reasoning (Dumontheil et al., 2022). 

So what does this mean, practically? For educators, it seems that curriculum design in STEM should not be done in isolation. Given the impact of semantic reasoning, it would be prudent to balance training in purely symbolic reasoning with training in semantic reasoning (e.g., by requiring humanities classes be taken with STEM classes). For cognitive neuroscientists, this research suggests that there may be another dimension to understanding counterintuitive reasoning: the complex causal relationships between visuo-spatial attention, inhibitory control, and counterintuitive reasoning. Indeed, this is a cautionary tale about the importance of inhibition in science itself—causation is difficult to establish, and the most intuitive models in science may not always be right, either.

 

References

Brookman-Byrne, A., Mareschal, D., Tolmie, A. K., & Dumontheil, I. (2018, June 21). Inhibitory control and counterintuitive science and maths reasoning in adolescence. PLoS ONE, 13(6), 1-19. https://doi.org/10.1371/journal.pone.0198973

Dumontheil, I., Brookman-Byrne, A., Tolmie, A. K., & Mareschal, D. (2022). Neural and Cognitive Underpinnings of Counterintuitive Science and Math Reasoning in Adolescence. Journal of Cognitive Neuroscience, 34(7), 1205. https://doi.org/10.1162/jocn_a_01854

Saenen, L., Heyvaert, M., Van Dooren, W., Schaeken, W., & Onghena, P. (2018). Why Humans Fail in Solving the Monty Hall Dilemma: A Systematic Review. Psychologica Belgica, 58(1), 128-158. https://doi.org/10.5334/pb.274

 

Seeing Without Light: Measuring Megahertz-Frequency Vibration on the Atomic Scale

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Scientists cannot take a picture of an atom. This is because visible light consists of waves so much larger than atoms that the two do not interact. Even supposed pictures of atoms, like this particularly famous one by British physicist David Nadlinger, show the radiation emitting from the atom – not the atom itself. So how else are we supposed to observe what happens at the atomic scale?

Vibration is an important key to link the quantum world with our own. Whereas visual observation is difficult on ultra-small scales, vibration still applies as a valid way to detect information. It’s like how you may be able to feel a splinter in your finger even though you can’t see it. For convenience, physicists often describe vibrations – periodic movement of atoms – as “phonons” (Chandler, 2010). Though phonons may sound like fundamental particles like protons or electrons, they aren’t. Phonons are just a way to describe complicated interactions between other fundamental particles into an easy-to-work-with particle form (Lewton, 2021). What we call heat is the same sort of approximation: it is an aggregate, easier way to describe the energy of the innumerable atoms in an object colliding like hundreds of billiard balls.

In Nature Physics, a team of researchers led by Caltech Professor Alkim Bozkurt recently created a device capable of reliably transforming phonons into detectable electromagnetic waves (2023). In their paper, published June of 2023, they describe an electrical circuit whose outputs vary with vibration.

Fundamental to the researchers’ design is a capacitor. Capacitors are circuit components that store electrical charges, i.e. electrons, on two parallel conducting plates separated by a small distance on their bodies. Capacitors are defined by their capacitance, which is the ability of a given component to hold charge. The key to Bozkurt et al.’s device is that capacitance depends on the distance between its parallel plates (2023). When the distance between the plates increases, capacitance decreases, and vice versa.

In the device described in the paper, Bozkurt et al. take advantage of capacitors’ properties to transmit photons (2023). The researchers connected the parallel plates of a calculator to a vibrating crystal lattice. When the lattice moves, the parallel plates – and thus capacitance –  change accordingly. Oscillating capacitance isn’t detectable on its own. However, voltage is a function of capacitance, and capacitance is the function of vibration. By hooking the capacitor up to a circuit whose output changes with voltage, we can observe the information carried by the phonons.

By hooking up the capacitor to a small transmitting circuit, the researchers can ascertain the phonons’ properties (Bozkurt et al., 2023). In operation, the wave transmitter must be tuned until the interaction between the moving capacitor and the transmitter creates a peak of detectable voltage in the transmitted wave. This peak occurs where the phonon frequency matches that of the transmitted microwave.

Say, for example, you have a crystal that vibrates at an unknown frequency 𝑓 that is greater than a millions of times per second. To find 𝑓, we attach the new device to the crystal. Then, once it begins vibrating, you must tune the transmitter’s electromagnetic wave output frequency to match the unknown 𝑓. When a peak of detectable voltage in the transmitted microwaves is observed, the output microwave frequency will equal to the unknown 𝑓. Thus, by measuring the microwaves, you will have indirectly measured the frequency of the vibrating crystal.

Such a device has practical applications well beyond measurement. The device can be used in parts of quantum memory units, interfacing with parts of quantum computers. It could effectively record the characteristic changes of a quantum system and then restore that state accordingly – something optical observing at such a small scale cannot achieve. Still, the invention is not quite able to match the phonon frequency as alternatives. Its outputs sometimes do not agree with the known vibration of the crystal. The paper cites possible next steps – including altering the transmitter – to increase its agreement with the known vibration of the phonons in testing (Bozkurt et al., 2023).

Still, this development is remarkable. The Caltech researchers produced a device that detects phonons at speeds of a billion times a second, orders of magnitude more sensitive than similar previous devices, with substantially improved reliability (Bozkurt et al., 2023). Other similar approaches rely on hard-to-create materials and suffer from short lifetimes at small scales.

Works Cited:

Bozkurt, A., Zhao, H., Joshi, C., LeDuc, H. G., Day, P. K., & Mirhosseini, M. (2022). A quantum electromechanical interface for long-lived phonons. Nature Physics, 19(September 2023), 1326–1332.

Brean, J. (2018, February 14). Stunning image of a single strontium atom wins British photography prize. https://nationalpost.com/news/world/stunning-image-of-a-single-strontium-atom

Chandler, D. L. (2010, July 8). Explained: Phonons. MIT News. https://news.mit.edu/2010/explained-phonons-0706

Lewton, T. (2021, March 24). The Near-Magical Mystery of Quasiparticles. Quantamagazine. https://www.quantamagazine.org/the-near-magical-mystery-of-quasiparticles-20210324/

 

 

The Power of Plant Cells: An Interview with Luis Vidali, PhD

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Walking around campus, we are surrounded by plants of various sizes — pines, grass, bushes, mosses. Despite the variety of size and characteristics, all these plants share a similar structure: their cytoskeleton. The cytoskeleton is the protein fibers found within the liquid cytoplasm of plant cells that maintain and modify their physical structure. It performs the same function in plants as the bone skeleton does in animals. But how does it function? How does a tiny seed develop into a large, sturdy tree?  

On October 11th I met with Dr. Luis Vidali, a scientist researching mechanisms in plant cell growth and reproduction, with a focus on studying the cytoskeleton of the moss species Physcomitrium patens. Born in Mexico before moving to the US to continue his studies after college, Dr. Vidali received his doctorate at the University of Massachusetts, Amherst, and is currently Associate Professor of Biology and Biotechnology at the Worcester Polytechnic Institute in Worcester, MA. 

 

Interview Transcript*: 

*At the time of the interview verbatim quotes could not be recorded. This transcript is based on notes taken during the interview and the transcript was submitted to Professor Vidali prior to publication to make sure his words were accurately represented. 

 

Luke Taylor: If you were to explain the implications of your research to the general public in a few words or sentences, what would you say? 

Dr. Luis Vidali: I study how plant cells grow, especially how plant cells take up more space as they grow. Studying the growth of plant cells is important because plants are integral to our everyday lives- from providing food, fibers, and fuels. Plants are responsible for all of these and all plants are made of microscopic cells with defined shapes. If you want to understand how plants grow, you need to understand plant cell growth.  

 

LT: Why is moss such a good model? 

LV: The model I use is Physcomitrium patens: spreading earth moss. We want plant models that grow fast and have a short reproductive cycle, to expedite the pace of researching the cells. Additionally, plants have a reproduction cycle that consists of alternation of generations, where the gametophyte is haploid (has one copy of each chromosome in its cells) and the sporophyte is diploid (has double the number of chromosomes in its cells). The generation we use is primarily the gametophyte, so it having fewer chromosomes in its cell for each generation allows us to identify mutations in its genome and find a demonstrated phenotype much faster than with diploid cells. The moss cells will eventually become identical to each other, allowing for easy control of experimentation without self-breeding techniques.  

 

LT: How do you circumvent the alternation of generations cycle with moss cells if you primarily work with the gametophyte? 

LV: The diploid sporophyte of the moss we work with makes brown capsules. We are not interested in these capsules; we are interested in the more dominant gametophyte. The reason we can circumvent the alternation of generations is because the spores develop protonemata, which are the filaments of cells growing from the moss gametophyte. We grind the moss every week to prevent the sporophyte from developing and propagating spores. The tools we use to perform this grinding are blenders not too unlike the ones in a kitchen blender, but could use a two-shaft, two-probe homogenizer as well.  

 

LT: You state that the cytoskeleton is one of the most conserved structures in plants, animals, and fungi. From what you have researched in plant cytoskeletal structure and function, which functions in plant cytoskeletons do you think may be conserved (paralleled) by fungi and animals, and which structures and functions do you believe diverged? 

LV: Conserved structures in all eukaryotic cells include the separation of chromosomes by the microtubules in the mitotic spindle, and the polarized transport of vesicles  mediated by actin. In evolution, cell division divergence includes the use of the phragmoplast exclusively in some green algae and plants. The phragmoplast is a complex including microtubules and actin which mediates the production of the cell plate during cytokinesis of the plant cell. In contrast, fungi and animal cells use actin and myosin to make the contractile ring, which squeezes the two daughter cells apart. 

 

LT: Myosin is one of the proteins of study in your lab. From my understanding, myosin is associated with animal muscle cells. How does myosin in plant cells relate to myosin use in animal cells? 

LV: Plant cells only have two classes of myosin proteins, whereas animal cells have several more classes, the most abundant one is myosin II,  (Which explains why animal muscle contraction may be the first thing to come to mind when one hears of myosin. Myosin class II in animal cells make contractile filaments with actin, whereas myosin class I mediate vesicle transportation with actin. These myosins in animal cells are related to stress fibers and their contractile nature. Plant cells lack these myosins: they only have myosin class VIII and XI. Myosin class XI is functionally homologous with myosin class V. Myosin V was present within the last common ancestor between plants and animals and mediates the transport of vesicles. The presence of myosin XI in plant cells shows the conserved nature of vesicle transportation in eukaryotic cells. In fungi, class V, I, and II myosins are present. And class II has a function like the one in the contractile ring seen in animal cells. This is an example of the phylogenetic closeness of the fungi kingdom to the animal kingdom in comparison to the plant kingdom to the animal kingdom. Myosin VIII in plant cells specifically mediates vesicle transportation of the phragmoplasts and plasmodesmata, a function specific to plant cells.   

 

LT: You have a collaboration with the department of physics at WPI. What does this entail in terms of your research and methods? Do you find the interdisciplinary nature of your research to be more enlightening about phytological research? How do you apply the principles of physics in your research?  

LV: In my lab we use biophysical and mathematical techniques to model the diffusion of vesicles and molecules in the cell. To do this, we first need to measure the diffusion coefficient of the particles. The diffusion coefficient provides information of how fast particles are moving in space and has units of µm2/s. Because the motion of particles is difficult to measure directly, we instead use the diffusion coefficient to estimate how fast particles may cover a given area in space. By using the plane of coverage as a function of time, we know it takes longer for the molecule or vesicle with a larger diffusion coefficient to cover a larger space.  In our experiments, we use reaction-diffusion calculations to measure how long vesicles bind to myosin, and we see that the vesicles bind to the myosin for very brief periods of time. These mathematical and physical models of diffusion allow us to understand the systems better and model changes in the rate of vesicle transport and secretion. 

We also use physics and mathematics to study the mechanical properties of plant cell walls. For our purposes, we model plant cell walls as a thin shell of a complex polysaccharide matrix, which behaves like a balloon. Having osmotic pressure of the plant cell will apply turgor pressure to the wall of the cells, causing it to expand and assume a more rigid form. The level we study the cell wall at is at the material rather than molecular level, generally speaking. We use an elastic model for the material properties of the cell wall, including considering tensions, stressors, and strains from the turgor pressure on the wall from osmosis. The purpose of our model is to make predictions about how the plant cell behaves, and as we continue to test these predictions, we update our model’s parameters accordingly.  

 

Related papers by Dr. Vidali and colleagues:  

Bibeau, J.P., Furt, F., Mousavi, S.I., Kingsley, J.L., Levine,M.F., Tüzel, E. and Vidali, L. (2020) In vivo interactions between myosin XI, vesicles and filamentous actin are fast and transient in Physcomitrella patens. J. Cell Sci. (2020) 133, jcs234682 doi: 10.1242/jcs.234682  

Chelladurai, D., Galotto, G., Petitto, J., Vidali, L., and Wu, M. (2020). Inferring lateral tension distribution in wall structures of single cells. Eur Phys J Plus 135, 662. https://doi.org/10.1140/epjp/s13360-020-00670-8. 

Galotto, G., Abreu, I., Sherman, C.A., Liu, B., Gonzalez-Guerrero, M., and Vidali, L. (2020) Chitin triggers calcium-mediated immune response in the plant model Physcomitrella patens. Molecular Plant-Microbe Interactions. doi: 10.1094/MPMI-03-20-0064-R 

Kingsley, J.L., Bibeau, J.P., Mousavi, S.I., Unsal, C., Chen, Z., Huang, X., Vidali, L., and Tüzel, E. (2018) Characterization of cell boundary and confocal effects improves quantitative FRAP analysis. Biophysical Journal. 114:1153-1164. doi:10.1016/j.bpj.2018.01.01.