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Tag: Nagoya University

  • Compact, swift typhoons are more impacted by global warming.

    Compact, swift typhoons are more impacted by global warming.

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    Newswise — A group from Nagoya University in Japan has found that larger, slower-moving typhoons are more likely to be resilient against global warming. However, compact, faster-moving storms are more likely to be sensitive. These findings suggest an improved method to project the strength of typhoons under global warming conditions. Their report was published in Geophysical Research Letters.

    Tropical cyclones are among the most dangerous weather systems in the world, causing disruption, damage, and death in East Asia. As global temperatures increase, so does the threat of typhoons. But projecting the strength and structure of such storms also becomes more difficult. Understanding changes in ocean response is essential to mitigate the worst effects of typhoons.

    One way to understand tropical cyclones is to examine the relationship between the atmosphere and the ocean. The ocean-atmosphere coupling relationship influences weather patterns, ocean circulation, and climate variability.

    This is especially important for typhoons as the intensity of tropical cyclones is linked to increases in sea surface temperature (SST). As the size of a cyclone increases, SST decreases, limiting its intensity. However, under global warming, the SST is higher. As a result, this could make a typhoon last longer.

    “The rise in sea temperatures is concerning because a typical compact, fast-moving storm, for example Typhoon Faxai in 2019, caused severe damage to eastern Japan,” warned lead researcher Sachie Kanada. “Our findings show the intensity of such typhoons can strengthen under global warming conditions.”

    To understand how global warming can affect typhoons, Kanada and fellow researcher Hidenori Aiki examined the buffering effect of atmosphere-ocean coupling on typhoons. They used the latest simulator of weather systems, an atmosphere-ocean model called CReSS-NHOES, to evaluate the effect of atmosphere ocean coupling on changes in the intensity of strong typhoons. CReSS-NHOES combines the cloud simulation model CReSS, developed at Nagoya University, with the oceanographic model NHOES, developed by the Japan Agency for Marine-Earth Science and Technology.

    The researchers used CReSS-NHOES to examine four powerful, but different-sized, typhoons in recent years: Trami (2018), Faxai (2019), Hagibis (2019), and Haishen (2020). These typhoons were all devastating; Trami and Faxai caused billions of dollars of damage and Hagibis led to the deaths of 118 people.

    Kanada and Aiki evaluated three scenarios: preindustrial era climate, a 2°C increase in SST, and a 4°C increase in SST. “We found that the degree to which typhoons strengthened per 1°C rise in SST varies significantly from typhoon to typhoon,” said Kanada. She was surprised by the change in hPa, a unit of pressure used in meteorology to measure atmospheric pressure and which represents the strength and intensity of a storm. “A typhoon, such as Trami, strengthens by only 3.1 hPa, while Faxai strengthens by as much as 16.2 hPa with a 1°C rise in SST.”

    The results of this study suggest that the atmosphere-ocean coupling effect buffers changes in storm intensity associated with global warming. But typhoons of different sizes may be affected differently. Storms with large eyes and small movement speeds cause SST to drop near their center, hindering their development. However, storms with small eyes and high movement speeds move away from the SST occurence. Such typhoons maintain constant heat at their center, increasing in intensity.

    Using these findings, the researchers created a new model to project the effect of tropical cyclones. They used a simple parameter called nondimensional storm speed (S0). Their model showed that S0 could distinguish between potentially destructive storms that are likely to strengthen under global warming and those that are resilient to the effects of global warming.

    “Currently, climate change projection research on typhoon intensity is conducted using models with coarse horizontal resolution or atmosphere-only models, which have difficulty reproducing the intensity and structure of strong typhoons,” Kanada explains. “This research using a high-resolution coupled regional atmosphere-ocean model can reproduce the intensity and structure of strong typhoons and the response of the ocean with high accuracy, so is expected to contribute not only to the quantitative projection of typhoon intensity under a warming climate, but also to the improvement of the accuracy of current typhoon intensity forecasts.”

    https://doi.org/10.1029/2023GL105659

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  • QR codes made more secure using beetle-inspired liquid crystals

    QR codes made more secure using beetle-inspired liquid crystals

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    Newswise — A research group led by Dr. Jialei He of Nagoya University’s Graduate School of Engineering has developed a method for processing cholesteric liquid crystals (CLCs) into micrometer-sized spherical particles. CLCs are a type of liquid crystal that possess a helical structure, giving them unique optical properties and the ability to selectively reflect light. By combining spherical CLC particles with commercially available pigments, the researchers developed a unique anti-counterfeiting QR code that can only be displayed under a specific circular polarizer. The results were published in the journal Advanced Optical Materials.

    CLCs are an example of how nature can be used in engineering. If you have ever noticed the iridescent wings of butterflies or the glossy coating on the exoskeletons of beetles, you have seen what CLCs can do. Once identified, CLCs that mimic the units that generate the colors of the exoskeletons of beetles are  synthesized in the laboratory because of their unusual colors and properties, which lie between liquids and crystals.

    Particularly useful are the optical properties of CLCs. They display unusual colors due to their unique molecular structure and optical properties that lead to the selective reflection of light at specific wavelengths. CLCs consist of long molecules that repeat themselves in the shape of a helix. In the helix, the vertical distance from where one region loops around and repeats itself is called the ‘pitch’. If the helix has repeating units that are close together, the liquid crystal has a short pitch and reflects shorter wavelengths of light, giving off blue and violet colors. However, those with a longer vertical space have longer wavelengths, leading to red or orange colors.

    To complicate matters further, because the molecules that make up the crystal are arranged in a helix, the color can change depending on the viewer’s orientation to the helix. Therefore, an infinite number of colors are possible depending on how the liquid crystal is viewed.

    To utilize CLCs more effectively, researchers make spherical CLC particles. These particles are spherical and include the helix in a 3D matrix so that scientists can better control their coloration. However, a major problem is size. Current methods create 100-micrometer spherical CLC particles, which is too large for most uses. To tackle this problem, researchers Jialei He (he/him) and Yukikazu Takeoka (he/him) from Nagoya University and their colleagues used a mixture of solvents to create spherical CLC particles with a controlled particle size of a few micrometers using a technique called dispersion polymerization.

    Since the samples were taken at room temperature, discovering the new technique was difficult. “The sample testing was a particularly challenging time due to the softness of the samples at room temperature, which is a property inherent to CLCs,” said Dr. He. “Consequently, a considerable amount of effort was required to find an appropriate method to characterize the samples without causing any damage.”

    Since the pitch of the cholesteric liquid crystal of spherical CLCs particles of this size varies with the curvature of the particles, the researchers made the particles spherical with a uniform size distribution. This is known as a monodisperse sphere. “During the experiment, we unexpectedly discovered that the particle size of the microspheres significantly influenced the resulting structural color. We could produce a variety of colors depending on particle size,” said Dr. He. “We also found that covering the spherical CLC particles with the polymer polydimethylsiloxane improved the coloration and thermal stability.”

    One potential application for this research is the creation of more secure QR codes that cannot be replicated. They could be created by taking advantage of a feature of the CLCs called chirality. Chirality refers to the property of an object or molecule that it cannot be superimposed onto its mirror image because of an asymmetry. CLCs are chiral and have optical activity, so an anti-counterfeiting QR code could be created by combining the color of spherical CLCs particles with commercially available non-chiral pigments. The code could only be read when a specific circular polarizer that allows the non-chiral light through but not the chiral light of the QR code is used..

    “The development of spherical CLC particles development resulting from this research will provide new possibilities for low-cost structural color functions different from those of conventional color materials,” said Dr. Takeoka. “As well as being used a special functional pigment for anti-counterfeiting, it can also be used for other applications that take advantage of the circularly polarized structural color with little angle dependence.”

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  • Researchers identify the neurons that synchronise female preferences with male courtship songs in fruit flies

    Researchers identify the neurons that synchronise female preferences with male courtship songs in fruit flies

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    Newswise — When it comes to courtship, it is important to ensure that one is interacting with a member of the same species. Animals use multiple sensory systems to confirm that potential mates are indeed suitable, with acoustic communication playing an important role in their decision making.   

    Although these differences have previously been reported at the behavioral level, it is not known how the neuronal circuitry underlying this decision-making has diverged between species. Now, in a new publication in Scientific Reports, a research group at Nagoya University in Japan has investigated how the auditory processing pathway has evolved and diverged between fruit fly species.  

    Males of several species of Drosophila (fruit flies), which are regularly used in neuroscience research, vibrate their wings rhythmically during courtship, producing a courtship song. The temporal components of these songs differ between species, allowing female flies to distinguish between potential mates. 

    “Identifying complex features, such as rhythm, requires information processing that involves not only the auditory organs but also neural circuits,” explains Yuki Ishikawa, the lecturer leading the project. “However, interspecies comparisons of the mechanism of rhythm discrimination have not been studied before because they require a more precise approach than just studying peripheral auditory organs.” 

    To find out what happens in the neural circuits during courtship, Professor Azusa Kamikouchi, Lecturer Yuki Ishikawa, and Graduate Student Takuro Ohashi of the Graduate School of Science first played songs with different rhythms to females of two closely related species of fruit flies (Drosophilia melanogaster and Drosophilia simulans), which have different courtship songs, to see which tones the females found acceptable. Confirming previous reports, the researchers found that Drosophilia simulans females preferred songs with distinct temporal components to those of Drosophilia melanogaster. 

    Building on these behavioral data, the researchers next used calcium imaging to determine how a specific subset of auditory neurons, called AMMC-B1, responded to different courtship songs between the species. They found that the responses of these neurons did indeed differ between species, and that these differences were consistent with previously observed behavioral responses.  

    “This is the first study to clarify how the evolution of the mechanism for distinguishing between rhythms of the same sound occurs,” explains Dr. Ishikawa. “Rhythmic information processing in neural circuits differs between fruit fly species. Using mathematical modeling, we have shown that this species difference may be due to a change in the balance between facilitation and inhibition in neural circuits.” 

    Despite the differences at the behavioral level, the group found that the overall characteristics of AMMC-B1 neurons are similar between the two species. This suggests that the properties of the neural circuit, at least in its early stages, are evolutionarily conserved. Thus, even in different species, they appear to be encoded by similar genes. These findings support the theory that the species-specificity of such neuronal cell groups emerged at a later stage of the auditory information- processing neural circuits. 

    “Drosophila melanogaster has neural mechanisms that are widely shared among animals,” Ishikawa said. “It is one of the most advanced animals for brain research because of the wealth of existing genetic tools. By introducing these tools into Drosophila simulans, this study was the first to make detailed interspecies comparisons of auditory neural circuits. By transferring these methods and results to closely related species, we can begin to study how information processing has evolved in the animal brain. We hope that the method established in this study will contribute to understanding the full picture of how mechanisms in the auditory brain have evolved.” 

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  • Scientists develop new device to detect brain tumors using urine

    Scientists develop new device to detect brain tumors using urine

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    Newswise — Researchers at Nagoya University in Japan have used a new device to identify a key membrane protein in urine that indicates whether the patient has a brain tumor. Their protein could be used to detect brain cancer, avoiding the need for invasive tests, and increasing the likelihood of tumors being detected early enough for surgery. This research could also have potential implications for detecting other types of cancer. The research was published in ACS Nano. 

    Although early detection of many types of cancer has contributed to the recent increases in cancer survival rates, the survival rate for brain tumors has remained almost unchanged for over 20 years. Partly this is due to their late detection. Physicians often discover brain tumors only after the onset of neurological symptoms, such as loss of movement or speech, by which time the tumor has reached a considerable size. Detecting the tumor when it is still small, and starting treatment as soon as possible. should help to save lives. 

    One possible sign that a person has a brain tumor is the presence of tumor-related extracellular vesicles (EVs) in their urine. EVs are nano-sized vesicles involved in a variety of functions, including cell-to-cell communication. Because those found in brain cancer patients have specific types of RNA and membrane proteins, they could be used to detect the presence of cancer and its progression.  

    Although they are excreted far from the brain, many EVs from cancer cells exist stably and are excreted in the urine without breaking down.  Urine testing has many advantages, explains Associate Professor Takao Yasui of Nagoya University Graduate School of Engineering. “Liquid biopsy can be performed using many body fluids, but blood tests are invasive,” he said. “Urine tests are an effective, simple, and non-invasive method because the urine contains many informative biomolecules that can be traced back to identify the disease.” 

    A research group led by Yasui and Professor Yoshinobu Baba of Nagoya University’s Graduate School of Engineering, in collaboration with Nagoya University’s Institute of Innovation for Future Society and the University of Tokyo, has developed a new analysis platform for brain tumor EVs using nanowires at the bottom of a well plate. Using this device, they identified two specific types of EV membrane proteins, known as CD31/CD63, from urine samples of brain tumor patients. Looking for these tell-tale proteins could enable doctors to identify tumor patients before they develop symptoms.  

    “Currently, EV isolation and detection methods require more than two instruments and an assay to isolate and then detect EVs,” said Yasui. “The all-in-one nanowire assay can isolate and detect EVs using one simple procedure. In the future, users can run samples through our assay and change the detection part, by selectively modifying it to detect specific membrane proteins or miRNAs inside EVs to detect other types of cancer. Using this platform, we expect to advance the analysis of the expression levels of specific membrane proteins in patients’ urinary EVs, which will enable the early detection of different types of cancer.” 

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  • New study deepens understanding of the regulation of circadian rhythms in the mammalian central clock

    New study deepens understanding of the regulation of circadian rhythms in the mammalian central clock

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    Newswise — Circadian rhythms are inherent cycles of approximately 24 hours that regulate various biological processes, such as sleep and wakefulness. A research group at Nagoya University in Japan has recently revealed that neural networks play an important role in the regulation of circadian rhythms through the mediation of an intracellular molecule called cyclic adenosine monophosphate (cAMP).

    This finding may pave the way for new strategies to treat sleep disorders and other chronic health conditions affected by disruption of the circadian rhythm. The study was published in the journal Science Advances.

    In living things, almost every cell contains a biological clock that regulates the cycle of circadian rhythms. In mammals, a group of neurons that form a structure called suprachiasmatic nucleus (SCN) is known as the master clock. It is located in the hypothalamus of the brain and synchronizes biological clocks in the peripheral tissues.

    Circadian rhythms are regulated by the transcription and translation mechanism of clock genes, which encode proteins that regulate daily cycles. However, some scientists suggest that in the SCN, so-called second messengers, such as cAMP and calcium ions, are also involved in the regulation of circadian rhythms. Second messengers are molecules that exist in a cell and mediate cell activity by relaying a signal from extracellular molecules.

    “The functional roles of second messengers in the SCN remain largely unclear,” said Dr. Daisuke Ono, the lead author of the study. “Among second messengers, cAMP is known as a particularly important molecule in various biological functions. Therefore, understanding the roles in the SCN may lead to new strategies for the treatment of sleep disorders and other health problems due to circadian rhythm disruption.”

    To investigate this issue, a Nagoya University research team led by Dr. Ono, in collaboration with Yulong Li of Peking University and Takashi Sugiyama of Evident Corporation, conducted a study focusing on cAMP in the SCN.

    The researchers first visualized the patterns of circadian rhythms of cAMP, using bioluminescent cAMP probes they developed. For comparison, they also visualized the rhythm patterns of calcium ions. When they blocked the function of a neural network, the rhythm of cAMP was lost, whereas the rhythm of calcium ions still existed. This suggests that in the SCN, the rhythm of cAMP is controlled by a neural network, while the rhythm of calcium ions is regulated by intracellular mechanisms.

    They next focused on an extracellular signaling molecule called vasoactive intestinal peptide (VIP). Its receptor is known to modulate cAMP in the SCN. To analyze how VIP affects the rhythm of cAMP, they inhibited VIP signaling. Their results showed a loss of the rhythm of cAMP, indicating that the intracellular cAMP rhythms are regulated by VIP in the SCN. If this is correct, then there should also be a circadian rhythm in the VIP release.

    To verify this, they introduced a G-protein-coupled receptor-activation-based (GRAB) VIP sensor using green fluorescent protein. Time-lapse imaging of the VIP release in the SCN revealed a clear circadian rhythm. Furthermore, this VIP release rhythm was abolished by blocking the function of a neural network. These results indicate that VIP is released rhythmically depending on neuronal activity and that the VIP release rhythm regulates the intracellular cAMP rhythm.

    Lastly, to determine how cAMP affects the rhythm of clock genes’ transcription and translation mechanisms, they conducted experiments using mice. They expressed a light-inducible enzyme called adenylate cyclase (bPAC) in the SCN slice and measured the protein level of the clock gene Per2, using bioluminescence imaging. They then irradiated the cells with blue light to verify the effect of cAMP on the circadian rhythm. The results showed that the manipulation of cAMP by blue light changed the circadian rhythm of the clock gene. They also manipulated the rhythm of cAMP in the SCN of living mice and found that the behavioral rhythm also shifted. These results suggest that intracellular cAMP affects both molecular and behavioral circadian rhythms that involve clock genes.

    “We concluded that intracellular cAMP rhythms in the SCN are regulated by VIP-dependent neural networks,” Ono explained. “Furthermore, the network-driven cAMP rhythm coordinates circadian molecular rhythms in the SCN as well as behavioral rhythms. In the future, we would like to elucidate the ancestral circadian clock, which is independent of clock genes and exists universally in life.”

     

    The study, “Network-driven intracellular cAMP coordinates circadian rhythm in the suprachiasmatic nucleus” was published online in the journal Science Advances on January 4, 2023, at DOI: http://www.science.org/doi/10.1126/sciadv.abq7032.

    Authors:

    Daisuke Ono, Huan Wang, Chi Jung Hung, Hsin-tzu Wang, Naohiro Kon, Akihiro Yamanaka, Yulong Li, and Takashi Sugiyama
     

    Funding:

    This work was supported by the Uehara Memorial Foundation, Kowa Life Science Foundation, Takeda Science Foundation, Kato Memorial Bioscience Foundation, DAIKO FOUNDATION, SECOM Science and Technology Foundation, Research Foundation for Opto-Science and Technology, The Nakatani Foundation for Advancement of Measuring Technologies in Biomedical Engineering, CASIO SCIENCE PROMOTION FOUNDATION, Innovation inspired by Nature” Research Support Program, SEKISUI CHEMICAL CO., LTD., Konica Minolta Science and Technology Foundation, The Inamori Foundation, Suntory Rising Stars Encouragement Program in life Sciences (SunRiSE) (to N.K.), JST FOREST Program (Grant Number JPMJFR211A, Japan), and the JSPS KAKENHI (21K19255, 21H02526, 21H00307, 21H00422, 20KK0177, 18H02477 to D.O.).

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  • Physicists confirm effective wave growth theory in space

    Physicists confirm effective wave growth theory in space

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    Newswise — A team from Nagoya University in Japan has observed, for the first time, the energy transferring from resonant electrons to whistler-mode waves in space. Their findings offer direct evidence of previously theorized efficient growth, as predicted by the non-linear growth theory of waves. This should improve our understanding of not only space plasma physics but also space weather, a phenomenon that affects satellites. 

    When people imagine outer space, they often envision it as a perfect vacuum. In fact, this impression is wrong because the vacuum is filled with charged particles. In the depths of space, the density of charged particles becomes so low that they rarely collide with each other. Instead of collisions, the forces related to the electric and magnetic fields filling space, control the motion of charged particles. This lack of collisions occurs throughout space, except for very near to celestial objects, such as stars, moons, or planets. In these cases, the charged particles are no longer traveling through the vacuum of space but instead through a medium where they can strike other particles. 

    Around the Earth, these charged-particle interactions generate waves, including electromagnetic whistler-mode waves, which scatter and accelerate some of the charged particles. When diffuse auroras appear around the poles of planets, observers are seeing the results of an interaction between waves and electrons. Since electromagnetic fields are so important in space weather, studying these interactions should help scientists predict variations in the intensity of highly energetic particles. This might help protect astronauts and satellites from the most severe effects of space weather.  

    A team comprising Designated Assistant Professor Naritoshi Kitamura and Professor Yoshizumi Miyoshi of the Institute for Space and Earth Science (ISEE) at Nagoya University, together with researchers from the University of Tokyo, Kyoto University, Tohoku University, Osaka University, and Japan Aerospace Exploration Agency (JAXA), and several international collaborators, mainly used data obtained using low-energy electron spectrometers, called Fast Plasma Investigation-Dual Electron Spectrometers, on board NASA’s Magnetospheric Multiscale spacecraft. They analyzed interactions between electrons and whistler-mode waves, which were also measured by the spacecraft. By applying a method of using a wave particle interaction analyzer, they succeeded in directly detecting the ongoing energy transfer from resonant electrons to whistler-mode waves at the location of the spacecraft in space. From this, they derived the growth rate of the wave. The researchers published their results in Nature Communications. 

    The most important finding was that the observed results were consistent with the hypothesis that non-linear growth occurs in this interaction. “This is the first time anybody has directly observed the efficient growth of waves in space for the wave-particle interaction between electrons and whistler-mode waves,” explains Kitamura. “We expect that the results will contribute to research on various wave-particle interactions and to also improve our understanding of the progress of plasma physics research. As more specific phenomena, the results will contribute to our understanding of the acceleration of electrons to high energies in the radiation belt, which are sometimes called ‘killer electrons’ because they inflict damage on satellites, as well as the loss of high-energy electrons in the atmosphere, which form diffuse auroras.” 

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  • Sleep mode makes Energy Internet more energy efficient

    Sleep mode makes Energy Internet more energy efficient

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    Newswise — A group of scientists in Nagoya University, Japan, have developed a possible solution to one of the biggest problems of the Internet of Energy, energy efficiency. They did so by creating a controller that has a sleep mode and only procures energy when needed. 

    Widespread generation of electricity based on renewable energy has become necessary to combat the climate crisis. One solution to realize society’s electrification needs is the Internet of Energy, which would operate like the information Internet, except that it would consist of energy linked by smart power generation, smart power consumption, smart interconnection, and cloud sharing.  

    When information is sent over the Internet, it is divided into transmittable units called ‘packets’, which are tagged with their destination.  The energy Internet is based on a similar concept. Information tags are added to power pulses to create units called ‘power packets’.  On the basis of requests from terminals, these are then distributed over networks to where they are needed. However, one problem is that since the packets are sent sporadically, the energy supply is intermittent. Current solutions, such as storage batteries or capacitors, complicate the system and reduce its efficiency.  

    An alternative solution is what is known as ‘sparse control’, where the terminal’s actuators are active part of the time and are in sleep mode for the rest of the time. In sleep mode, they do not consume fuel or electricity, leading to efficient energy saving and reducing environmental and noise pollution.  Although sparse control has been used with a single actuator, it does not necessarily provide good performance when multiple actuators are used. The problem of determining how to do this for multiple actuators is called the ‘maximum turn-off control problem’. 

    Now, a Nagoya University research group, led by Professor Shun-ichi Azuma and Doctoral student Takumi Iwata of the Graduate School of Engineering, has developed a model control scheme for multiple actuators. The model has an awake mode, during which it procures and controls the necessary power packets for when they are needed, and a sleep mode. The research was published in the International Journal of Robust and Nonlinear Control. 

    “We can see our research being useful in the motor control of production equipment,” explains Professor Azuma. “This research provides a control system configuration method based on the assumption that the energy supply is intermittent. It has the advantage of eliminating the need for storage batteries and capacitors. It is expected to accelerate the practical application of the power packet type energy Internet.” 

    This research was supported by Japan Science and Technology Agency Emergent Research Support Program and Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan. 

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