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Showing posts from February, 2020

Our Century-Old Notion of Wind Turbine Efficiency Is Going Through Some Turbulence

In 1920, a young German engineer named Albert Betz peered down at his calculations. Although interest in renewable energy was a long way from reaching its peak, he’d been exploring how wind turbines capture energy from the air. In the process, he had come up with a calculation for the greatest possible efficiency of any wind turbine: a shockingly tidy sixteen twenty-sevenths, or 59.3 percent. Since then, this number has been known as the Betz limit, serving as a virtually impossible goal for efficiency—until now. “In order to make that calculation, [Betz] had to make some simplifying assumptions,” says John Dabiri, a professor of mechanical engineering at the California Institute of Technology. In particular, he chose to approximate all wind as perfectly steady. “Now, we know that’s untrue because the wind is turbulent,” says Dabiri. “If I’m standing on a wind farm, there will be gusts so the wind won’t be a fixed value.” Further complicating the situation, popular propeller-style tu

The Identity Gap: How feelings of belonging push women out of physics

“You’re too pretty to be a physicist” “Why are you in graduate school if you’re just going to leave once you have kids”? “You don’t look like you study physics. I mean that as a compliment” If you’re a female physicist, odds are you’ve heard something along the lines of this. Oof. In a recent discussion on twitter, women shared micro and microaggressions they’ve heard about their career paths, and unsurprisingly, the results weren’t great. It’s no secret that STEM is a male-dominated field, physics especially. You’ll see it right away when you walk into Physics 101 at any university. While other disciplines are seeing significant increases in female representation, physics has been the slowest discipline to show any progress. A new study from Physical Review PER shows that a lack of feedback and recognition contributes to a large gender gap in physics. There are many reasons why this is the case. As a society, we’re not great at teaching physics . Traditional methods of tea

International Day of Light Pre-celebration Edition: An Ultrasound Without the Goo?

Ultrasound is a powerful tool for looking inside the body. The scans see through layers of tissue to reveal pumping hearts, developing fetuses, troublesome blood clots, and injured muscles. They are relatively low-cost, portable, and have few side effects. Patients aren’t exposed to ionizing radiation or confined in a small space. They are, however, slathered in goo. Most of the time, having a body part temporarily coated in a cold, sticky substance and then pressed on by a technician is a small price to pay for an accurate diagnosis. But in some situations, like when it’s necessary to image a wound, this contact can be painful. That’s one of the downsides of ultrasound technology. Another is that some results can be influenced by the amount of pressure applied by the technician–it’s a very “hands-on” technique, especially compared to other types of medical imaging. In new research published in the journal Light: Science & Applications, a team of researchers from the Massachuse

Beyond Breakfast: The Cheerios Effect, Tilting Disks, and Why Measuring it All Matters

Daniel Harris prefers Cinnamon Toast Crunch, but he’s spent a lot of time talking about Cheerios lately. And cleaning them up. The cleaning up is thanks to his 1-year-old daughter, but the talking is courtesy of his latest physics research project. Harris is a professor at Brown University who studies fluids and how they interact with solid objects. He doesn’t study breakfast cereal per se, but even cereal follows the laws of physics. Cheerios in Milk. Credit: Photo by on Unsplash. It turns out that one of the same physical interactions that governs the behavior of the last few Cheerios in a bowl of milk also enables water-walking insects to climb onto land and tiny particles to self-assemble into small but functional machines. The better we understand these forces, the better position we’re in to harness them in designs for next-generation robots, medical devices, environmental sensors, and other technological advances. With this in mind, a team composed of Harr

Too Much of a Good Thing? Why Cells Throw Away Essential Chemicals

The human body can be a little pessimistic, constantly hoarding any excess nutrients just in case things go south. From an evolutionary perspective, this makes sense—when you don’t know where your next meal is coming from, being able to hang onto your resources can make the difference between life and death. Cells on the other hand, have long puzzled researchers with their tendency to throw away essential chemicals without any apparent regard for the future. “The chemicals in a cell can basically be classified into two groups: metabolites and proteins,” explains Jumpei Yamagishi, a first-year graduate student at the University of Tokyo. As cells take in nutrients, such as sugars, fats, and proteins, they use the comparatively small metabolites, like amino acids, as intermediaries to break down the nutrients and release the energy stored in their chemical bonds. Without metabolites, the cells can quite literally starve to death in a sea of abundance—yet they persist in releasing the e

How Metal Responds to a Strike: Surprising Results on Heat Generation and Energy Storage

“Strike while the iron is hot” is a well-known adage meant to inspire immediate action. Researcher Juan Carlos Nieto-Fuentes is spreading a slightly different message: Strike and the iron is hot. Nieto-Fuentes is a researcher at the University Carlos III of Madrid in Spain studying what happens to metal objects during high-speed collisions. The more we know about how metal responds to such impacts, the better equipped we are to design vehicles that can protect passengers in a crash, armor that can shield soldiers from enemy strikes, and metal structures that can withstand shocks. One of those responses is generating heat. From top to bottom, this series of thermal images reveal the temperature increase of a metal cylinder (tantalum) during high-speed deformation. The colors go from cold (black) to hot (white). Credit: Daniel Rittel. In research recently published in the American Physical Society’s journal Physical Review Letters, conducted while Nieto-Fuentes was working at th

So, you want to blow a giant bubble?

According to the Guinness Book of World Records, the largest blown free-floating soap bubble currently stands (the record, the bubble has since popped) at 96.27 m3 (that’s a whopping 5.7 m diameter!). To put that in context, a bubble that size could hold an entire Volkswagen Beetle. In terms of the longest bubble, the world record stands at 32 meters, that’s longer than a basketball court! One could even say its..unbeleivabubble. As large as these bubbles are, they somehow maintain a wall thickness of only a few microns - that’s one one-hundredth the thickness of a sheet of paper. So why can such fragile bubbles grow to such large sizes? A team of physicists at Emory University is working on it . The author’s recreation of the world record largest bubble. While at a conference in Madrid, physicist Justin Burton was walking the streets when he came across street performers blowing massive soap bubbles. Upon returning home his sister bought him a bubble wand. Burton won