Suramya's Blog : Welcome to my crazy life…

October 7, 2023

Oxford researchers develop promising 3D printing method for repairing brain injuries

Filed under: Emerging Tech,Science Related — Suramya @ 11:59 PM

Brain injuries are traditionally extremely hard for us to cure with the current state of medical knowledge. Mild cases of Traumatic brain injury (TBI) or concussion can be treated with rest and slow return to normal activities. However, for severe TBI’s the care mostly focuses on stabilizing the patient, ensuring the brain is getting enough enough oxygen, controlling blood and brain pressure, and preventing further injury to the head or neck. Post stabilization if the patient is stable we use therapies to recover functions, relearn skills etc. But that is just training the brain to use different neurons to perform tasks that the damaged ones used to do.

The researchers at the University of Oxford have had a breakthrough that brings the ability to provide tailored repairs for those who suffer brain injuries. The researchers demonstrated for the first time that neural cells can be 3D printed to mimic the architecture of the cerebral cortex. This research has been published in Nature Communications earlier this month.

Engineering human tissue with diverse cell types and architectures remains challenging. The cerebral cortex, which has a layered cellular architecture composed of layer-specific neurons organised into vertical columns, delivers higher cognition through intricately wired neural circuits. However, current tissue engineering approaches cannot produce such structures. Here, we use a droplet printing technique to fabricate tissues comprising simplified cerebral cortical columns. Human induced pluripotent stem cells are differentiated into upper- and deep-layer neural progenitors, which are then printed to form cerebral cortical tissues with a two-layer organization. The tissues show layer-specific biomarker expression and develop a structurally integrated network of processes. Implantation of the printed cortical tissues into ex vivo mouse brain explants results in substantial structural implant-host integration across the tissue boundaries as demonstrated by the projection of processes and the migration of neurons, and leads to the appearance of correlated Ca2+ oscillations across the interface. The presented approach might be used for the evaluation of drugs and nutrients that promote tissue integration. Importantly, our methodology offers a technical reservoir for future personalized implantation treatments that use 3D tissues derived from a patient’s own induced pluripotent stem cells.

I did try reading the paper but it pretty much went over my head. However I am extremely happy to see significant progress being made in this field and look forward to reading more about this technology as it is refined and improved.

Source: Oxford researchers develop 3D printing method that shows promise for repairing brain injuries

– Suramya

July 26, 2023

New Double sided solar panels nearly double the power production per panel

Filed under: Emerging Tech,Science Related — Suramya @ 11:12 PM

Solar Panels have come a long way in the last few decades and their efficiency has been consistently increasing over the time as well. We have gone from an efficiency of ~10% on an average to more than 25% today. Now researchers from US Department of Energy’s National Renewable Energy Laboratory (NREL) have created a new double sided solar panel that generates electricity from both sides of the panel. Basically it uses reflected light on the back side of the panel to generate power. Even though the amount of power generated by the backside of the panel is only ~90% of the power generated by the front end adding them both together means that a single panel is generating almost double the power than traditional panels.

Bifacial photovoltaics (PV) harvest solar irradiance from both their front and rear surfaces, boosting energy conversion efficiency to maximize their electrical power production. For single-junction perovskite solar cells (PSCs), the performance of bifacial configurations is still far behind that of their state-of-the-art monofacial counterparts. Here, we report on highly efficient, bifacial, single-junction PSCs based on the p-i-n (or inverted) architecture. We used optical and electrical modeling to design a transparent conducting rear electrode for bifacial PSCs to enable optimized efficiency under a variety of albedo illumination conditions. The bifaciality of the PSCs was about 91%–93%. Under concurrent bifacial measurement conditions, we obtained equivalent, stabilized bifacial power output densities of 26.9, 28.5, and 30.1 mW/cm2 under albedos of 0.2, 0.3, and 0.5, respectively. We further showed that bifacial perovskite PV technology has the potential to outperform its monofacial counterparts with higher energy yields and lower levelized cost of energy (LCOE).

This is a significant breakthrough and the research was published in the journal Joule titled “Highly efficient bifacial single-junction perovskite solar cells”.

I love the fact that renewable energy is getting so much more push nowadays. I have been exploring putting solar at my place, but since I am in an apartment I don’t have much options available that would make financial sense. The panels I could put up would barely supply enough power making the whole thing not cost effective. Parents have put solar at our house in Delhi and my cousin has done the same at their farm where most of their power consumption is managed by their solar setup.

– Suramya

June 26, 2023

BepiColombo takes fabulous photos during its flyby of Mercury 236 km above the planet’s surface

Filed under: Astronomy / Space,Science Related — Suramya @ 9:10 PM

Mercury, the closest planet to the Sun has been a challenge to explore and examine because of its closeness to the Sun. This is the second craft to orbit the planet after NASA’s MESSENGER probe, which orbited the planet from 2011 to 2015. BepiColombo is a joint venture between European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). The latest flyby was 3rd of the 6 planned flybys of the planet. The team has released a short video composed of 217 images taken during the flyby.


Photo taken by BepiColombo during its 3rd flyby of Venus

Pic Credit: European Space Agency/ Japan Aerospace Exploration Agency

The closest approach took place at 19:34 UTC (21:34 CEST) on 19 June 2023, about 236 km above the planet’s surface, on the night side of the planet.

Approaching on the nightside of the planet, a few features started to appear out of the shadows about 12 minutes following the closest approach, when BepiColombo was already about 1800 km from the surface. The planet’s surface became more optimally illuminated for imaging from about 20 minutes after close approach and onwards, corresponding to a distance of about 3500 km and beyond. In these closer images, a bounty of geological features are visible, including a newly named crater.

While not apparent in these flyby images, the nature of the dark material associated with Manley Crater and elsewhere will be explored further by BepiColombo from orbit. It will seek to measure just how much carbon it contains and what minerals are associated with it, in order to learn more about Mercury’s geological history.

The next Mercury flyby will happen in September 2024 but the next next long solar electric propulsion ‘thruster arc’ is planned to start early August until mid-September which will help BepiColombo in Braking against the gravitational pull of the Sun. During the lifetime of the project, the module will have completed 15,000 hours of solar electric propulsion operations which will allow it to perform 9 planetary flybys in total — one at Earth, two at Venus, and six at Mercury.

The more we explore our celestial neighbors, the more information we will have before we start working towards space colonization and building settlements. Although, I don’t think that Mercury will be a contender in the near future for a settlement, unless we find a rare mineral or something over there.

Source: Slashdot: New Video Shows a Flyby of the Planet Mercury – with AI-Assisted Music

– Suramya

June 21, 2023

India launches 2nd Gen satellite for the NavIC Navigation System

Filed under: Astronomy / Space,Science Related — Suramya @ 1:07 PM

GPS has become so ingrained in our life that it is hard to imagine a world before GPS. I remember having to use paper maps and asking folks for directions during our road trips and now I don’t need to worry about anything, just follow the map and you can find anything. Even during my mountaineering course back in 1999 we learnt how to navigate and how to figure out where you were using landmarks. Towards the end of the course the instructor showed us a GPS receiver (which was ridiculously expensive at that time) as something that was available but couldn’t be relied upon because it was too expensive and might not be available. Now we have watches with built in GPS so the technology has come a long way since then.

However, since GPS is a US controlled system they have the ability to disable it for any area if they want and that creates a major risk. In the Kargil war, US disabled GPS for the entire region making it difficult for them to figure out where they were and perform the attacks more safely. This highlighted the risk and strategic importance of the functionality for India and they started working on an indigenous replacement.

Other countries have also realized the same and implemented their own version of GPS, these include Russian GLONASS, European Galileo, Japanese QZSS (Covers Japan and surrounding areas), and Chinese BeiDou. India’s replacement is called NavIC, which means sailor in Hindi. It is an regional satellite navigation system that provides accurate real-time positioning and timing services and currently covers India and a region extending 1,500 km (930 mi) around it. The system went live in 2018 via seven satellites. These satellites only operated in the L-5 band and S-band frequencies which are not supported in civilian equipment so wasn’t available for civilian use. After the Galileo constellation was granted approval to use the L1 band India also requested access and was granted permission by the International Telecommunication Union to use the L1 and L2 frequency bands.

On 29th May 2023, ISRO successfully placed the NVS-01 navigation satellite into orbit. This second generation satellite supports the L1 band which means the device manufacturers such as GPS receivers and smartphones just need a software update to support navigation using NavIC instead of needed extra hardware which was the case with the previous generation of the system. ISRO is planning on launching a satellite every six months over the next few years to put 11 new satellites in orbit so that the system has redundancy.

NVS-01 is the first of the second-generation satellites envisaged for the Navigation with Indian Constellation (NavIC) services. NVS series of satellites will sustain and augment the NavIC with enhanced features. This series incorporates L1 band signals additionally to widen the services. For the first time, an indigenous atomic clock will be flown in NVS-01.

For now the system is concentrating on the Indian subcontinent and the area around it but as more satellites are launched they are planning on covering the entire globe and provide users with an alternative to GPS.

Source: EurAsian Times: Backstabbed During Pakistan War, India ‘Ditches’ US GPS For ‘Much More Accurate’ NavIC Navigation System

– Suramya

June 7, 2023

Proof of Concept setup demoing technology to beam solar power down to Earth successfully demoed

Filed under: Astronomy / Space,Emerging Tech,Science Related — Suramya @ 4:20 PM

The ability to beam power from space to earth has long been a staple of Science Fiction books and movies. On the surface it makes sense, space is huge and if we can setup solar panels in space to collect energy and get it to earth in a usable format then it is a win-win. No more having to deal with fossil fuels/nuclear reactors etc. Folks have been working on this for over 5 decades now and progress was slow as most people focused their efforts on other options such as improving land based solar panels, geothermal etc etc.

Now researchers from California Institute of Technology (Caltech) have successfully demonstrated MAPLE (Microwave Array for Power-transfer Low-orbit Experiment) which is an array of 32 flat antennas packed onto a surface slightly larger than a dinner plate. During the experiment the energy was transmitted to earth and successfully received by a receiver on the roof of the Gordon and Betty Moore Laboratory of Engineering and they were able to successfully target receivers about a foot away alternatively and transmit ~200 milliwatts of power to the receiver that powered a LED light.

Using constructive and destructive interference between individual transmitters, a bank of power transmitters is able to shift the focus and direction of the energy it beams out—without any moving parts. The transmitter array uses precise timing-control elements to dynamically focus the power selectively on the desired location using the coherent addition of electromagnetic waves. This enables the majority of the energy to be transmitted to the desired location and nowhere else.

MAPLE features two separate receiver arrays located about a foot away from the transmitter to receive the energy, convert it to direct current (DC) electricity, and use it to light up a pair of LEDs to demonstrate the full sequence of wireless energy transmission at a distance in space. MAPLE tested this in space by lighting up each LED individually and shifting back and forth between them. The experiment is not sealed, so it is subject to the harsh environment of space, including the wide temperature swings and solar radiation that will be faced one day by large-scale SSPP units.
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MAPLE also includes a small window through which the array can beam the energy. This transmitted energy was detected by a receiver on the roof of the Gordon and Betty Moore Laboratory of Engineering on Caltech’s campus in Pasadena. The received signal appeared at the expected time and frequency, and had the right frequency shift as predicted based on its travel from orbit.

This is a big step forward, but I still have major doubts about the feasibility of the project, at least in the current form. Here we are using microwaves to transmit the energy from space to earth, at the level of power we need to transmit the microwave beam will cook anything that crosses it, for example if a plane flies through the beam you can say goodbye to the passengers. Even if we decide that we will establish a no-fly zone around the area what is to stop birds etc from flying into the beam and getting fried. Another problem is that microwave beams generate heat as a side-effect and that can cause a major heating of the atmosphere and change the air-currents which can cause a massive environmental impact.

We also need to consider that in order to collect the solar energy at a scale where it would be useful and make financial sense we would need to setup massive solar-panels in space. This will case a huge problem for astronomers. We already have issues being caused by the Starlink Satellites, this will be the same but at a much larger scale.

However, that being said I see the potential and if we can ever get quantum entanglement or spooky action at a distance as Einstein called it working reliably and consistently then that could potentially be used to transmit the power to earth without frying everyone in the path.

Lets see what else the researchers come up with…

Source: Caltech.edu: In a First, Caltech’s Space Solar Power Demonstrator Wirelessly Transmits Power in Space
Science.org: Satellite beams solar power down to Earth, in first-of-a-kind demonstration

– Suramya

August 23, 2022

Water droplets can turn to Hydrogen Peroxide when hitting a surface

Filed under: Science Related — Suramya @ 3:36 PM

Science and Technology are fascinating fields and everyday there are new discoveries that show us how amazing the world around us is and how much more we have to learn. Today I learnt that water can be converted to Hydrogen Peroxide if the water droplets are small enough. The phenomena was discovered three years ago by researchers at Stanford University when they sprayed small drops of water onto a special strip of paper that turns blue in the presence of hydrogen peroxide – the main ingredient in bleach. Interestingly other researchers have had problems replicating the results so the team spent the past few years trying to understand why it happens and how.

They mixed water with dye that glows in the presence of hydrogen peroxide and then injected the mixture into microscopic channels made of glass like silica and they found that the liquid was glowing when passing through the tubes. They then found that the water contained hydrogen peroxide at a concentration of 0.0019 grams per liter after passing through the channel. The theory is that the liquid takes electrons from the channels and causing the water molecules, which are made of two hydrogen atoms and one oxygen atom, to reconfigure into hydrogen peroxide molecules, which have an additional oxygen.

Contact electrification between water and a solid surface is crucial for physicochemical processes at water–solid interfaces. However, the nature of the involved processes remains poorly understood, especially in the initial stage of the interface formation. Here we report that H2O2 is spontaneously produced from the hydroxyl groups on the solid surface when contact occurred. The density of hydroxyl groups affects the H2O2 yield. The participation of hydroxyl groups in H2O2 generation is confirmed by mass spectrometric detection of O in the product of the reaction between 4-carboxyphenylboronic acid and O–labeled H2O2 resulting from O2 plasma treatment of the surface. We propose a model for H2O2 generation based on recombination of the hydroxyl radicals produced from the surface hydroxyl groups in the water–solid contact process. Our observations show that the spontaneous generation of H2O2 is universal on the surfaces of soil and atmospheric fine particles in a humid environment.

This effect could be a possible explanation of why certain viruses don’t spread as quickly during the high humidity season of the year. As the hydrogen peroxide being created would act as a disinfectant to kill the viruses. If we can consistently get this to occur then it would be a quick and easy way to do a basic disinfection of a high movement area. However, before practical implementations can be discussed there is still a lot of work to be done.

Paper: Water–solid contact electrification causes hydrogen peroxide production from hydroxyl radical recombination in sprayed microdroplets
Source: Water droplets can sometimes turn into bleach when hitting a surface

– Suramya

June 30, 2022

Help NASA find clouds on Mars to solve the mystery of the low atmospheric pressure on Mars

Filed under: Astronomy / Space,Science Related — Suramya @ 3:29 AM

If you have some free time and are fascinated by Mars, you can use your spare time to help NASA figure out why Mars’ atmosphere is just 1% as dense as Earth’s. The air pressure on mars is so low that liquid water just vaporizes from the planet’s surface into the atmosphere. The really interesting part is that originally (a few billion years ago) Mars had a lot thicker atmosphere.

You don’t need special skill to help with this, as the project is focusing on the study of Martian clouds. Specifically, volunteers will be looking at scientific data collected over 16 years to identify cloud formations. It might seem like a simple thing but once the clouds are identified we can look at other data captured at the same time such as temperature, time of the day, season etc which will help scientists create maps of where they form, determine what they’re made of (water, carbon dioxide, or dust), and see how they change throughout the day and through the seasons.


Cloudspotting on Mars asks members of the public to look for arches such as this one (center) in data collected by NASA’s Mars Reconnaissance Orbiter (Source: NASA)

It will involve looking at graphs such as the one above to look for arches (spikes) that can indicate clouds. If you are interested, you can join from the project’s website.

Thanks to Digital Trends: NASA wants your help to solve an enduring Mars mystery for the link.

– Suramya

May 27, 2022

Creating robots with no moving parts or computational ability which can navigate through mazes on their own

Filed under: Emerging Tech,Science Related — Suramya @ 11:34 PM

One would imagine that it takes skill or at least the ability to think to escape from a maze, unless you count running around like a headless chicken as a skill. However, Jie Yin and his colleagues at North Carolina State University have created a contraption that has no computational ability or moving parts but is still able to escape from a maze using trial and error.

The device is shaped like a pasta and is made from a rubber like material impregnated with liquid crystals. When this device is placed on a heated surface the parts in contact with the surface heat up and expand while the rest of the device remains the same this causes a twisting motion that allows it to roll at a speed of up to 3.8 millimetres per second. Even more interestingly this ‘robot’ can navigate a maze, when it reaches an obstacle such as a wall its orientation changes slightly and can sometimes continue moving. If that doesn’t work, then it continues to push against the obstacle which creates changes in the tension in the device allowing it to change the orientation of the arc’s on its surface to another direction, which would enable it to roll in the opposite direction. These two abilities enable it to continually change direction when meeting obstacles, bumping from surface to surface, eventually finding its way out despite lacking any intelligent control.

Autonomy is crucial for soft robotics that are constructed of soft materials. It remains challenging to create autonomous soft robots that can intelligently interact with and adapt to changing environments without external controls. To do so, it often requires an analogical soft “brain” that integrates on-board sensing, control, computation, and decision-making. Here, we report an autonomous soft robot embodied with physical intelligence for decision-making via adaptive soft body-environment interactions and snap-through instability, without integrated sensing and external controls. This study harnesses physical intelligence as a new paradigm for designing autonomous soft robots that can interact intelligently with their environments, thus potentially reducing the burdens on the conventional integrated sensing, control, computations, and decision-making systems in designing intelligent soft robots.

Soft robots that can harvest energy from environmental resources for autonomous locomotion is highly desired; however, few are capable of adaptive navigation without human interventions. Here, we report twisting soft robots with embodied physical intelligence for adaptive, intelligent autonomous locomotion in various unstructured environments, without on-board or external controls and human interventions. The soft robots are constructed of twisted thermal-responsive liquid crystal elastomer ribbons with a straight centerline. They can harvest thermal energy from environments to roll on outdoor hard surfaces and challenging granular substrates without slip, including ascending loose sandy slopes, crossing sand ripples, escaping from burying sand, and crossing rocks with additional camouflaging features. The twisting body provides anchoring functionality by burrowing into loose sand. When encountering obstacles, they can either self-turn or self-snap for obstacle negotiation and avoidance. Theoretical models and finite element simulation reveal that such physical intelligence is achieved by spontaneously snapping-through its soft body upon active and adaptive soft body-obstacle interactions. Utilizing this strategy, they can intelligently escape from confined spaces and maze-like obstacle courses without any human intervention. This work presents a de novo design of embodied physical intelligence by harnessing the twisting geometry and snap-through instability for adaptive soft robot-environment interactions.

This technology could be used to create cheap robots that can explore environments to take sensor readings and can potentially function inside the human body when made in microscopic scale. Since they don’t have any moving parts and don’t require power sources it would allow them to function for a longer duration than powered alternatives which would eventually run out of power. Plus, since they don’t require batteries it would be safer for people to ingest them without potentially harmful effects because most of the power sources in use today have some harmful chemicals in them.

The team’s findings have been published in the Proceedings of the National Academy of Sciences (PNAS) Journal: Twisting for soft intelligent autonomous robot in unstructured environments earlier this week.

Source: New Scientist: Pasta-shaped robot with no moving parts can navigate through mazes

– Suramya

May 14, 2022

Using algae sealed in a AA battery to generate enough electricity to run a microprocessor for 6 months

Powering computers and all our devices requires us to use batteries if they can’t be connected to a power source/electrical socket. For the most part this means that we use NiCa or Lithium batteries. The problem with this is that they require us to use rare earth metals that are hard to find and process, which makes them expensive and mining the metals are potentially bad for the environment. The other problem is that they need frequent replacement and create a lot of waste. Due to this a lot of effort is going on to find better ways of generating power.

Now, Christopher Howe and other researchers from the University of Cambridge have managed create a power source using blue-green algae to generate enough electricity to power a processor performing calculations (to simulate load). Using a type of cyanobacteria called Synechocystis sp. PCC 6803 sealed in a container about the size of an AA battery, made of aluminum and clear plastic they were able to generate the 0.3 microwatts of power to run the CPU for 45 minutes followed by 15 minutes of standby, which required 0.24 microwatts of power.

The system ran without additional intervention for 6 months and the computer was placed on a windowsill at one of the researchers’ houses during the test and the ambient light was enough to power the processor. There are indications that this can be scaled up to generate more power for more resource intensive applications but even if that doesn’t work out, the current setup could potentially be used to power IoT devices that don’t require that much power to run such as sensors/monitors deployed in the forests/cities for monitoring.

Sustainable, affordable and decentralised sources of electrical energy are required to power the network of electronic devices known as the Internet of Things. Power consumption for a single Internet of Things device is modest, ranging from μW to mW, but the number of Internet of Things devices has already reached many billions and is expected to grow to one trillion by 2035, requiring a vast number of portable energy sources (e.g., a battery or an energy harvester). Batteries rely largely on expensive and unsustainable materials (e.g., rare earth elements) and their charge eventually runs out. Existing energy harvesters (e.g., solar, temperature, vibration) are longer lasting but may have adverse effects on the environment (e.g., hazardous materials are used in the production of photovoltaics). Here, we describe a bio-photovoltaic energy harvester system using photosynthetic microorganisms on an aluminium anode that can power an Arm Cortex M0+, a microprocessor widely used in Internet of Things applications. The proposed energy harvester has operated the Arm Cortex M0+ for over six months in a domestic environment under ambient light. It is comparable in size to an AA battery, and is built using common, durable, inexpensive and largely recyclable materials.

Their research has been published in the Energy & Environmental Science journal and work is ongoing to build on top of it to look at commercial applications.

Source: A colony of blue-green algae can power a computer for six months

– Suramya

May 10, 2022

Using ancient techniques for adding secret images in bronze mirrors to hide images in Liquid Crystal displays

Filed under: Emerging Tech,Interesting Sites,Science Related — Suramya @ 1:28 AM

There are a lot of things that were accomplished by our ancestors that seem like they should be impossible and this is why the theory that aliens were involved in our past to give us a boost is so popular. People don’t realize that just because it wasn’t possible in the western world doesn’t mean that others in the world couldn’t do it. In this post I am going to talk about Chinese/Japanese Magic mirrors that were first created ~200BC but modern science was only able to explain how they work in 2005 when M V Berry published an paper describing the optics of how this would work.

The Magic Mirror is a type of mirror that was popular in ancient china, specially the Han dynasty (206 BC – 24 AD). The specialty of these mirrors is that they were made out of solid bronze with the front side polished brightly so that it can be used as a mirror whereas the back would have a design cast in the metal. When a bright light was reflected by the mirror and shone against a wall the pattern on the back of the mirror would be projected onto the wall.


Example of how the Magic Mirror reflections look (Pic credit: Faena.com)

As you can imagine this is extremely hard to do. Due to trading with the Chinese, folks over in Korea and Japan have also been known to create these mirrors which are known as Makyō (magic mirrors) over there. One difference between Makyō and the Chinese mirror is that a Makyō doesn’t reflect the image on the back on the mirror when light hits it, nor does it have any obvious irregularities on its reflecting surface. But still it creates these fantastical images where nothing should be there. More details on how the mirrors were constructed and the history behind them are available here.

It took western scientists over 2000 years to figure out the science behind these mirrors, kind of.. as evident from the explanation below.

Although the surface of the mirrors is polished and seems completely flat, it has subtle convex and concave curves caused by the designed. Convex curves (outwards) scatter light and darken their areas of reflection. For their part, concave curves focus light and illuminate their areas of reflection. Mirrors are made of forged bronze, and the thickest parts are cooled at a different speed than the thin ones. Since the metal contracts a little as it is cooled, the different ranges of cooling “stress” or slightly deform the metal. The thin areas are also more flexible than the thick parts, so the polishing process, which should smoothen the metal until uniformity is achieved, exaggerates the slight differences in thickness. While we cannot see the pattern on the surface of the mirror, photos very clearly delineate it, so when they are able to bounce off the mirror’s curves, the pattern emerges.

Using the understanding gained from Berry’s paper Felix Hufnagel and his colleagues from the University of Ottawa in Canada to create a modern version of the magic mirror using liquid crystal which is a different state of matter (their molecules are both fluid and arranged in patterns). By applying an electric current to the liquid crystals they were able to tailor the orientation of the molecules which allowed them to create an image which would only show up when a particular combination of current/amplitude was applied. The images created using this technique look clear even when viewed from different angles which can be used to improve projectors for 3D images.

Their paper was published in Optica earlier this month and is an interesting (if confusing read).

Interesting links:
Wikipedia: Chinese Magic Mirror
Secret images hidden in mirrors and windows using liquid crystals

– Suramya

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