If you made a motor out of a magnet, a wire coil, and some needles, you probably remember that motors and generators depend on a rotating magnetic field. Once you know how it works, the concept is pretty simple, but did you ever wonder who worked it all out to start with? Tesla figures into it, unsurprisingly. But what about Michael Dobrowolsky or Walter Bailey? Not common names to most people. [Learn Engineering] has a slick video covering the history and theory of rotating magnetic field machines, and you can watch it below.
Motors operated on direct current were not very practical at the time and caused a jerky motion. However, Tesla and another inventor named Ferraris realized that AC current could cause a rotating magnetic field without a moving commutator.
Today we’re sad to report that one of the primary support cables at the Arecibo Observatory has snapped, nudging the troubled radio telescope closer to a potential disaster. The Observatory’s 300 meter reflector dish was already badly in need of repairs after spending 60 years exposed to the elements in Puerto Rico, but dwindling funds have made it difficult for engineers to keep up. Damage from 2017’s Hurricane Maria was still being repaired when a secondary support cable broke free and smashed through the dish back in August, leading to grave concerns over how much more abuse the structure can take before a catastrophic failure is inevitable.
The situation is particularly dire because both of the failed cables were attached to the same tower. Each of the remaining cables is now supporting more weight than ever before, increasing the likelihood of another failure. Unless engineers can support the dish and ease the stress on these cables, the entire structure could be brought down by a domino effect; with each cable snapping in succession as the demands on them become too great.
Workers installing the reflector’s mesh panels in 1963.
As a precaution the site has been closed to all non-essential personnel, and to limit the risk to workers, drones are being used to evaluate the dish and cabling as engineers formulate plans to stabilize the structure until replacement cables arrive. Fortunately, they have something of a head start.
Back in September the University of Central Florida, which manages the Arecibo Observatory, contacted several firms to strategize ways they could address the previously failed cable and the damage it caused. Those plans have now been pushed up in response to this latest setback.
Unfortunately, there’s still a question of funding. There were fears that the Observatory would have to be shuttered after Hurricane Maria hit simply because there wasn’t enough money in the budget to perform the relatively minor repairs necessary. The University of Central Florida stepped in and provided the funding necessary to keep the Observatory online in 2018, but they may need to lean on their partner the National Science Foundation to help cover the repair bill they’ve run up since then.
The Arecibo Observatory is a unique installation, and its destruction would be an incredible blow for the scientific community. Researchers were already struggling with the prospect of repairs putting the powerful radio telescope out of commission for a year or more, but now it seems there’s a very real possibility the Observatory may be lost. Here’s hoping that teams on the ground can safely stabilize the iconic instrument so it can continue exploring deep space for years to come.
As a carnivorous plant, Venus flytraps have always been a fascinating subject of study. One of their many mysteries is how they differentiate an insect visit from less nutritious stimulants such as a windblown pebble. Now scientists are one step closer to deciphering the underlying mechanism, assisted by a new ability to visualize calcium changes in real time.
Calcium has long been suspected to play an important part in a Venus flytrap’s close/no-close decision process, but scientists couldn’t verify their hypothesis before. Standard chemical tests for calcium would require cutting the plant apart, which would only result in a static snapshot. The software analogy would be killing the process for a memory dump but unable to debug the process at runtime. There were tantalizing hints of a biological calcium-based analog computer at work, but mother nature had no reason to evolve JTAG test points on it.
Lacking in-circuit debug headers, scientists turned to the next best thing: add diagnostic indicator lights. But instead of blinking LEDs, genes were added to produce a protein that glows in the presence of calcium. Once successful, they could work with the engineered plants and get visual feedback. Immediately see calcium levels change and propagate in response to various stimuli over different time periods. Confirming that the trap snaps shut only in response to patterns of stimuli that push calcium levels beyond a threshold.
With these glowing proteins in place, researchers found that calcium explained some of the behavior but was not the whole picture. There’s something else, suspected to be a fast electrical network, that senses prey movement and trigger calcium release. That’ll be something to dig into, but at least we have more experience working with electrical impulses and not just for plants, either.
The incandescent light bulb was one of the first early applications of electricity, and it’s hard to underestimate its importance. But before the electric light, people didn’t live in darkness — they thought of ways to redirect sunlight to brighten up interior spaces. This was made possible through the understanding of the basic principles of optics and the work of skilled glassmakers who constructed prism tiles, deck prisms, and vault lights. These century-old techniques are still being applied today for the diffusion of LEDs or for increasing the brightness of LCD displays.
Semantics First!
People in optics are a bit sloppy when it comes to the definition of a prism. While many of them are certainly not geometric prisms, Wikipedia defines it as a transparent optical element with flat, polished surfaces of which at least one is angled. As can be seen in the pictures below some of the prisms here do not even stick to this definition. Browsing the catalog of your favorite optics supplier you will find a large variety of prisms used to reflect, invert, rotate, disperse, steer, and collimate light. It is important to point out that we are not so much interested in dispersive prisms that split a beam of white light into its spectrum of colors, although they make great album covers. The important property of prisms in this article is their ability to redirect light through refraction and reflection.
A Safe Way to Bring Light Under Deck
A collection of deck lights used to direct sunlight below deck in ships. Credit: glassian.org
One of the most important uses of prism lighting was on board ships. Open flames could have disastrous consequences aboard a wooden ship, so deck prisms were installed as a means to direct sunlight into the areas below decks. One of the first patents for deck lights “THE GREAT AND DURABLE INCREASE OF LIGHT BY EXTRAORDINARY GLASSES AND LAMPS” was filed by Edward Wyndus as early as 1684. Deck prisms had typical sizes of 10 to 15 centimeters. The flat top was installed flush with the deck and the sunlight was refracted and directed downward from the prism point. Because of the reversibility of light paths (“If I can see you, you can see me”) deck prisms also helped to spot fires under deck. Continue reading “Prism Lighting – The Art Of Steering Daylight”→
Just over a fortnight ago, RV Polarstern, a German research vessel, sailed back into port, heralding the end of the largest Arctic research project ever undertaken. The MOSAiC expedition, short for Multidisciplinary drifting Observatory for the Study of Arctic Climate, spent a full year running experiments to measure conditions at the North Pole, and research how the unique Arctic climate is being affected by human activity.
Unprecedented In Size And Scope
The operation was regularly resupplied by visits from other icebreakers, bringing equipment, food, and fresh personnel. Alfred-Wegener-Institut / Jan Rohde (CC-BY 4.0)
With a budget exceeding €140 million, and with over 300 scientists attached to the project, the expedition aimed to study a full year-long ice cycle in the Arctic region. To achieve this, the research vessel of the project, RV Polarstern, was navigated into an ice floe, and allowed to freeze in and drift with the ice pack. As the seasons progressed, the vessel drifted with the sea ice across the polar region. Along the way, a series of rotating research teams set up equipment on the ice and took regular measurements, investigating several scientific focus areas. Different groups observed atmospheric conditions and the sea ice itself, with researchers also focusing on biogeochemistry, the ocean, and the ecosystems in the area.
Icebreakers were used to transport goods and personnel to the RV Polarstern over the duration of the mission. The project faced issues in spring, as a pre-planned changeover executed by aircraft had to be abandoned due to restrictions brought about by the COVID-19 pandemic. Instead, this was also executed by ship, with the Polarstern temporarily leaving the ice to rendezvous with RV Sonne and RV Maria S. Merian for the changeover of approximately 100 crew and to pick up provisions. The detour took three weeks, but didn’t have any major negative impacts on the mission. Continue reading “MOSAiC Project Freezes A Boat In The Arctic Ice Pack For Science”→
It sounds like science fiction — and until 2012, the ability to cheaply and easily edit strings of DNA was exactly that. But as it turns out, CRISPR/Cas9 gene editing is a completely natural function in which bacteria catalogs its interactions with viruses by taking a snippet of the virus’ genetic material and filing it away for later.
Now, two women have won the 2020 Nobel Prize in Chemistry “for developing a method for genome editing”. Emmanuelle Charpentier and Jennifer Doudna leveraged CRISPR into a pair of genetic scissors and showed how sharp they are by proving that they can edit any string of DNA this way. Since Emmanuelle and Jennifer published their 2012 paper on CRISPR/Cas9, researchers have used these genetic scissors to create drought-resistant plants and look for new gene-based cancer therapies. Researchers are also hoping to use CRISPR/Cas9 to cure inherited diseases like Huntington’s and sickle cell anemia.
The discovery started with Emmanuelle Charpentier’s investigation of the Streptococcus pyogenes bacterium. She was trying to understand how its genes are regulated and was hoping to make an antibiotic. Once she teamed up with Jennifer Doudna, they found a scientific breakthrough instead.
Emmanuelle Charpentier was born December 11th, 1968 in Juvisy-sur-Orge, France. She studied biochemistry, microbiology, and genetics at the Pierre and Marie Curie University, which is now known as Sorbonne University. Then she received a research doctorate from Institut Pasteur and worked as a university teaching assistant and research scientist. Dr. Charpentier is currently a director at the Max Planck Institute for Infection Biology in Berlin, and in 2018, she founded an independent research unit.
Upon completion of her doctorate, Dr. Charpentier spent a few years working in the States before winding up at the University of Vienna where she started a research group. Her focus was still on the bacteria Streptococcus pyogenes, which causes millions of people to suffer through infections like tonsillitis and impetigo each year. It also causes sepsis, which officially makes it a flesh-eating bacterium.
We didn’t realize that dog training research techniques were so high-tech. Operant conditioning, as opposed to Pavlovian, gives a positive reward, in this case dog treats, to reinforce a desired behavior. Traditionally operant conditioning involved dispensing the treat manually and some devices do exist using wireless remote controls, but they are still manually operated and can give inconsistent results (too many or too few treats). There weren’t any existing methods available to automate this process, so this team decided to rectify the situation.
They took a commercial treat dispenser and retro-fitted it with an interface board that taps into the dispenser’s IR sensors to detect that the hopper is moving and treats were actually dispensed. The interface board connects to a Raspberry Pi which serves as a full-featured platform to run the tests. In this demonstration it connects to an HDMI monitor, detecting touches from the dog’s nose to correlate with events onscreen. Future researchers won’t have to reinvent the wheel, just redesign the test itself, because [Walker] and [Jeffrey] have released all the firmware and hardware as open-source on the lab’s GitHub repository.
In the short video clip below, watch the dog as he gets a treat when he taps the white dot with his snout. If you look closely, at one point the dog briefly moves the mouse pointer as well. We predict by next year the C-CHIL researchers will have this fellow drawing pictures and playing checkers.
