Computers Math

A University of Minnesota Twin Cities research team has developed a new microfluidic chip for diagnosing diseases that uses a minimal number of components and can be powered wirelessly by a smartphone. The innovation opens the door for faster and more affordable at-home medical testing.
The researchers’ paper is published in Nature Communications, a peer-reviewed, open access, scientific journal published by Nature Research. Researchers are also working to commercialize the technology.
Microfluidics involves the study and manipulation of liquids at a very small scale. One of the most popular applications in the field is developing “lab-on-a-chip” technology, or the ability to create devices that can diagnose diseases from a very small biological sample, blood or urine, for example.
Scientists already have portable devices for diagnosing some conditions — rapid COVID-19 antigen tests, for one. However, a big roadblock to engineering more sophisticated diagnostic chips that could, for example, identify the specific strain of COVID-19 or measure biomarkers like glucose or cholesterol, is the fact that they need so many moving parts.
Chips like these would require materials to seal the liquid inside, pumps and tubing to manipulate the liquid, and wires to activate those pumps — all materials that are difficult to scale down to the micro level. Researchers at the University of Minnesota Twin Cities were able to create a microfluidic device that functions without all of those bulky components.
“Researchers have been extremely successful when it comes to electronic device scaling, but the ability to handle liquid samples has not kept up,” said Sang-Hyun Oh, a professor in the University of Minnesota Twin Cities Department of Electrical and Computer Engineering and senior author of the study. “It’s not an exaggeration that a state-of-the-art, microfluidic lab-on-a-chip system is very labor intensive to put together. Our thought was, can we just get rid of the cover material, wires, and pumps altogether and make it simple?”
Many lab-on-a-chip technologies work by moving liquid droplets across a microchip to detect the virus pathogens or bacteria inside the sample. The University of Minnesota researchers’ solution was inspired by a peculiar real-world phenomenon with which wine drinkers will be familiar — the “legs,” or long droplets that form inside a wine bottle due to surface tension caused by the evaporation of alcohol. More

When designing a next-generation quantum computer, a surprisingly large problem is bridging the communication gap between the classical and quantum worlds. Such computers need a specialized control and readout electronics to translate back and forth between the human operator and the quantum computer’s languages — but existing systems are cumbersome and expensive.
However, a new system of control and readout electronics, known as Quantum Instrumentation Control Kit, or QICK, developed by engineers at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, has proved to drastically improve quantum computer performance while cutting the cost of control equipment.
“The development of the Quantum Instrumentation Control Kit is an excellent example of U.S. investment in joint quantum technology research with partnerships between industry, academia and government to accelerate pre-competitive quantum research and development technologies,” said Harriet Kung, DOE deputy director for science programs for the Office of Science and acting associate director of science for high-energy physics.
The faster and more cost-efficient controls were developed by a team of Fermilab engineers led by senior principal engineer Gustavo Cancelo in collaboration with the University of Chicago whose goal was to create and test a field-programmable gate array-based (FPGA) controller for quantum computing experiments. David Schuster, a physicist at the University of Chicago, led the university’s lab that helped with the specifications and verification on real hardware.
“This is exactly the type of project that combines the strengths of a national laboratory and a university,” said Schuster. “There is a clear need for an open-source control hardware ecosystem, and it is being rapidly adopted by the quantum community.”
Engineers designing quantum computers deal with the challenge of bridging the two seemingly incompatible worlds of quantum and classical computers. Quantum computers are based on the counterintuitive, probabilistic rules of quantum mechanics that govern the microscopic world, which enables them to perform calculations that ordinary computers cannot. Because people live in the macroscopic visible world where classical physics reigns, control and readout electronics act as the interpreter connecting these two worlds. More

Building a plane while flying it isn’t typically a goal for most, but for a team of Harvard-led physicists that general idea might be a key to finally building large-scale quantum computers.
Described in a new paper in Nature, the research team, which includes collaborators from QuEra Computing, MIT, and the University of Innsbruck, developed a new approach for processing quantum information that allows them to dynamically change the layout of atoms in their system by moving and connecting them with each other in the midst of computation.
This ability to shuffle the qubits (the fundamental building blocks of quantum computers and the source of their massive processing power) during the computation process while preserving their quantum state dramatically expands processing capabilities and allows for the self-correction of errors. Clearing this hurdle marks a major step toward building large-scale machines that leverage the bizarre characteristics of quantum mechanics and promise to bring about real-world breakthroughs in material science, communication technologies, finance, and many other fields.
“The reason why building large scale quantum computers is hard is because eventually you have errors,” said Mikhail Lukin, the George Vasmer Leverett Professor of Physics, co-director of the Harvard Quantum Initiative, and one of the senior authors of the study. “One way to reduce these errors is to just make your qubits better and better, but another more systematic and ultimately practical way is to do something which is called quantum error correction. That means that even if you have some errors, you can correct these errors during your computation process with redundancy.”
In classical computing, error correction is done by simply copying information from a single binary digit or bit so it’s clear when and where it failed. For example, one single bit of 0 can be copied three times to read 000. Suddenly, when it reads 001, it’s clear where the error is and can be corrected. A foundational limitation of quantum mechanics is that information can’t be copied, making error correction difficult.
The workaround the researchers implement creates a sort of backup system for the atoms and their information called a quantum error correction code. The researchers use their new technique to create many of these correction codes, including what’s known as a toric code, and it spreads them out throughout the system. More

Researchers at the University of California San Diego have developed a smartphone app that could allow people to screen for Alzheimer’s disease, ADHD and other neurological diseases and disorders — by recording closeups of their eye.
The app uses a near-infrared camera, which is built into newer smartphones for facial recognition, along with a regular selfie camera to track how a person’s pupil changes in size. These pupil measurements could be used to assess a person’s cognitive condition.
The technology is described in a paper that will be presented at the ACM Computer Human Interaction Conference on Human Factors in Computing Systems (CHI 2022), which will take place from April 30 to May 5 in New Orleans as a hybrid-onsite event.
“While there is still a lot of work to be done, I am excited about the potential for using this technology to bring neurological screening out of clinical lab settings and into homes,” said Colin Barry, an electrical and computer engineering Ph.D. student at UC San Diego and the first author of the paper, which received an Honorable Mention for Best Paper award. “We hope that this opens the door to novel explorations of using smartphones to detect and monitor potential health problems earlier on.”
Pupil size can provide information about a person’s neurological functions, recent research has shown. For example, pupil size increases when a person performs a difficult cognitive task or hears an unexpected sound.
Measuring the changes in pupil diameter is done by performing what’s called a pupil response test. The test could offer a simple and easy way to diagnose and monitor various neurological diseases and disorders. However, it currently requires specialized and costly equipment, making it impractical to perform outside the lab or clinic. More

In a proof-of-concept study, researchers have created self-assembled, protein-based circuits that can perform simple logic functions. The work demonstrates that it is possible to create stable digital circuits that take advantage of an electron’s properties at quantum scales.
One of the stumbling blocks in creating molecular circuits is that as the circuit size decreases the circuits become unreliable. This is because the electrons needed to create current behave like waves, not particles, at the quantum scale. For example, on a circuit with two wires that are one nanometer apart, the electron can “tunnel” between the two wires and effectively be in both places simultaneously, making it difficult to control the direction of the current. Molecular circuits can mitigate these problems, but single-molecule junctions are short-lived or low-yielding due to challenges associated with fabricating electrodes at that scale.
“Our goal was to try and create a molecular circuit that uses tunneling to our advantage, rather than fighting against it,” says Ryan Chiechi, associate professor of chemistry at North Carolina State University and co-corresponding author of a paper describing the work.
Chiechi and co-corresponding author Xinkai Qiu of the University of Cambridge built the circuits by first placing two different types of fullerene cages on patterned gold substrates. They then submerged the structure into a solution of photosystem one (PSI), a commonly used chlorophyll protein complex.
The different fullerenes induced PSI proteins to self-assemble on the surface in specific orientations, creating diodes and resistors once top-contacts of the gallium-indium liquid metal eutectic, EGaIn, are printed on top. This process both addresses the drawbacks of single-molecule junctions and preserves molecular-electronic function.
“Where we wanted resistors we patterned one type of fullerene on the electrodes upon which PSI self-assembles, and where we wanted diodes we patterned another type,” Chiechi says. “Oriented PSI rectifies current — meaning it only allows electrons to flow in one direction. By controlling the net orientation in ensembles of PSI, we can dictate how charge flows through them.”
The researchers coupled the self-assembled protein ensembles with human-made electrodes and made simple logic circuits that used electron tunneling behavior to modulate the current.
“These proteins scatter the electron wave function, mediating tunneling in ways that are still not completely understood,” Chiechi says. “The result is that despite being 10 nanometers thick, this circuit functions at the quantum level, operating in a tunneling regime. And because we are using a group of molecules, rather than single molecules, the structure is stable. We can actually print electrodes on top of these circuits and build devices.”
The researchers created simple diode-based AND/OR logic gates from these circuits and incorporated them into pulse modulators, which can encode information by switching one input signal on or off depending on the voltage of another input. The PSI-based logic circuits were able to switch a 3.3 kHz input signal — which, while not comparable in speed to modern logic circuits, is still one of the fastest molecular logic circuits yet reported.
“This is a proof-of-concept rudimentary logic circuit that relies on both diodes and resistors,” Chiechi says. “We’ve shown here that you can build robust, integrated circuits that work at high frequencies with proteins.
“In terms of immediate utility, these protein-based circuits could lead to the development of electronic devices that enhance, supplant and/or extend the functionality of classical semiconductors.”
The research appears in Nature Communications. Co-authors Chiechi and Qiu were formerly at University of Groningen, the Netherlands.
Story Source:
Materials provided by North Carolina State University. Original written by Tracey Peake. Note: Content may be edited for style and length. More

The December 2014 North American Storm Complex was a powerful winter storm, referred to by some as California’s “Storm of the Decade.” Fueled by an atmospheric river originating over the tropical waters of the Pacific Ocean, the storm dropped 8 inches of rainfall in 24 hours, sported wind gusts of 139 miles per hour, and left 150,000 households without power across the San Francisco Bay Area.
Writing in Weather and Climate Extremes this week, researchers described the potential impacts of climate change on extreme storms in the San Francisco Bay area, among them the December 2014 North American Storm Complex.
Re-simulating five of the most powerful storms that have hit the area, they determined that under future conditions some of these extreme events would deliver 26-37% more rain, even more than is predicted simply by accounting for air’s ability to carry more water in warmer conditions.
However, they found these increases would not occur with every storm, only those that include an atmospheric river accompanied by an extratropical cyclone.
The research — funded by the City and County of San Francisco and in partnership with agencies including the San Francisco Public Utilities Commission, Port of San Francisco, and San Francisco International Airport — will help the region plan its future infrastructure with mitigation and sustainability in mind.
“Having this level of detail is a game changer,” said Dennis Herrera, General Manager of the San Francisco Public Utilities Commission, which was the lead City agency on the study. “This groundbreaking data will help us develop tools to allow our port, airport, utilities, and the City as a whole to adapt to our changing climate and increasingly extreme storms.”
These first-of-their-kind forecasts for the city were made possible by the Stampede2 supercomputer at the Texas Advanced Computing Center (TACC) and the Cori system at the National Energy Research Scientific Computing Center (NERSC) — two of the most powerful supercomputers in the world, supported by the National Science Foundation and Department of Energy respectively. More

In the quest to build smart skin that mimics the sensing capabilities of natural skin, ionic skins have shown significant advantages. They’re made of flexible, biocompatible hydrogels that use ions to carry an electrical charge. In contrast to smart skins made of plastics and metals, the hydrogels have the softness of natural skin. This offers a more natural feel to the prosthetic arm or robot hand they are mounted on, and makes them comfortable to wear.
These hydrogels can generate voltages when touched, but scientists did not clearly understand how — until a team of researchers at UBC devised a unique experiment, published today in Science.
“How hydrogel sensors work is they produce voltages and currents in reaction to stimuli, such as pressure or touch — what we are calling a piezoionic effect. But we didn’t know exactly how these voltages are produced,” said the study’s lead author Yuta Dobashi, who started the work as part of his master’s in biomedical engineering at UBC.
Working under the supervision of UBC researcher Dr. John Madden, Dobashi devised hydrogel sensors containing salts with positive and negative ions of different sizes. He and collaborators in UBC’s physics and chemistry departments applied magnetic fields to track precisely how the ions moved when pressure was applied to the sensor.
“When pressure is applied to the gel, that pressure spreads out the ions in the liquid at different speeds, creating an electrical signal. Positive ions, which tend to be smaller, move faster than larger, negative ions. This results in an uneven ion distribution which creates an electric field, which is what makes a piezoionic sensor work.”
The researchers say this new knowledge confirms that hydrogels work in a similar way to how humans detect pressure, which is also through moving ions in response to pressure, inspiring potential new applications for ionic skins. More

Harnessing the power that makes the sun and stars shine could be made easier by powerful magnets with straighter shapes than have been made before. Researchers linked to the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have found a way to create such magnets for fusion facilities known as stellarators.
Such facilities have complex twisted magnetic coils, compared with the straight up-and-down coils in more widely used tokamak facilities, and can produce fusion reactions without the risk of disruptions that tokamaks face. This advantage makes stellarators a candidate to serve as the model for a next-generation fusion pilot plant.
Now, by adding sections to the stellarator coils that are relatively straight, researchers could both reduce the manufacturing cost and make it easier to install openings that would allow technicians to repair the device’s interior. Both innovations could aid the development of a stellarator power plant, replicating fusion on Earth for a virtually inexhaustible supply of power to generate electricity without producing greenhouse gases or long-lived radioactive waste.
“In the future, people will have to replace components within stellarators as they wear out, which requires large openings between the coils of the magnets,” said physicist Caoxiang Zhu, an author of the paperreporting the results in Nuclear Fusion who completed the research when he was on staff at PPPL. He is now on staff at the University of Science and Technology of China. “But it’s hard to have large openings in stellarators because the electromagnetic coils zig and zag and are really complex.” But by using a mathematical technique known as “spline representation,” Zhu and the other collaborators were able to design magnets with straighter sections than before while still creating magnetic fields that can confine plasma. Those straight sections could provide good locations for windows.
Invented by astrophysicist Lyman Spitzer, PPPL’s first director, stellarators are fusion facility concepts that use high-powered magnets to create interweaving magnetic fields that confine plasma, hot gas consisting of electrons and bare atomic nuclei. Stellarators have advantages over tokamaks, doughnut-shaped devices that are currently the most popular fusion facility concept worldwide, but their fantastically complicated magnets have made design and construction challenging.
Zhu and the researchers added the spline capability to Zhu’s FOCUS computer code. To test the concept, the team designed magnets that could fit on the Helically Symmetric eXperiment (HSX), a stellarator at the University of Wisconsin-Madison.
The updated code showed that researchers could create straighter magnets than before while preserving their strength and accuracy. “In principle, you can always make straighter coils, but the trade-off is that their magnetic fields might not confine the plasma as well as those produced by twistier coils,” said Nicola Lonigro, a student in the DOE’s Science Undergraduate Laboratory Internship (SULI) program at the time of the research, lead author of the paper, and now a Ph.D. candidate at the University of York in Britain. “But our research showed that you could make a simpler coil with straighter sections that makes the same magnetic field shape and strength as conventional ones do.”
Creating simpler magnets could aid the development of a stellarator fusion power plant. “In the long term, this work is a contribution to the larger effort trying to make stellarators commercially viable,” Lonigro said.
This research was supported by the DOE’s Office of Science (Fusion Energy Sciences and Workforce Development for Teachers and Scientists).
Story Source:
Materials provided by DOE/Princeton Plasma Physics Laboratory. Original written by Raphael Rosen. Note: Content may be edited for style and length. More