By Roy Kilgard, Research Associate Professor of Astronomy, Wesleyan University. Simulation of two neutron stars merging. NASA/AEI/ZIB/M. Koppitz and L. Rezzolla, CC BY When LIGO, the Laser Interferometer Gravitational-Wave Observatory, first detected gravitational waves from merging black holes, it opened up a new window in astrophysics and provided the most powerful confirmation yet of Einstein’s theory of general relativity. Continue reading “Why astrophysicists are over the moon about observing merging neutron stars”→
Scientists recreated ice planets’ diamond rain. There’s a lot going on in there. NASA When subjected to the pressures (and temperatures) of life on other planets, even familiar substances can get pretty alien. Case in point: the diamond rains of the ice giants. Scientists have long thought that massive planets like Neptune and Uranus—which contain relatively… Continue reading “Uranus is probably full of giant diamonds”→
The scientists are all talking like it’s a sure thing.
On August 21, the “moon” will pass between the Earth and the sun, obscuring the light of the latter. The government agency NASA says this will result in “one of nature’s most awe-inspiring sights.” The astronomers there claim to have calculated down to the minute exactly when and where this will happen, and for how long. They have reportedly known about this eclipse for years, just by virtue of some sort of complex math.
This seems extremely unlikely. I can’t even find these eclipse calculations on their website to check them for myself.
Meanwhile the scientists tell us we can’t look at it without special glasses because “looking directly at the sun is unsafe.”
Hit the link for a laugh. Relief from too much negativity…
I am really looking forward to watching the Monday’s solar eclipse. I’ll be in North Georgia at my in-laws’ house that will have 99.5% total coverage. I am ready with my Space.com and NOAA approved viewing glasses for this event. I remember the total eclipse in 1970. I was with my Great Aunt Tillie in Savannah and was eerie. The street lights came on, birds went to roost. I was all prepared with a viewing box that the instructions were given in the Weekly Reader at school. Unfortunately, it was overcast, so I couldn’t use it.
Viewing glasses have been flying off the shelves here and the displays that I saw at the grocery store last week have all disappeared.
So, here is a guide of making your own, home brew eclipse viewer…
To build your own, get a carton and cut a hole in one side, big enough to poke your head through. Paste white paper on the inside surface that you will be facing. Then punch a pinhole into the opposite side, high enough so that the little shaft of light will miss your head. For a sharper image you can make a better pinhole by cutting a one inch square hole in the carton, taping a piece of aluminum foil over this hole and then making the pinhole in the foil. Finally, tape the box shut and cover all light leaks with black tape.
“You gotta Crash and Learn.” A fan takes a selfie with Kari Byron. 4-H National Council Mixing art and science started very early for Kari Byron. “I remember distinctly sitting there with a Cheerio box and a roll of tape, and trying to recreate a human skull, like a little sculpture,” she says, recalling her earliest… Continue reading “How art could help encourage kids to study science”→
Almost 6 months ago, media sources were speculating on the prices of Tesla’s solar roofing tiles – and now, the numbers are in. In contrast to the original price tag of $24.50 per square foot that was previously estimated by Consumer Reports, Tesla announced in May that the tiles would be $21.85 – roughly 20% less… Continue reading “Tesla solar roof is cheaper than yours”→
“Take the stairs!” we’ve all been implored, to help maintain our health. But what if taking the stairs is painful, difficult or, worse, potentially dangerous?
In most public buildings, we can opt for an elevator or escalator ride. But at home (unless you live solely on the ground floor), taking the stairs is usually a necessity, not a choice. And as people lose mobility with age, injury or disease, it becomes more challenging. Stair negotiation is one of the top five most difficult physical tasks for older adults; in one study almost half of nondisabled older adults reported trouble climbing up stairs, and more than a quarter reported problems going down stairs.
My research collaborator, Karen Liu, a computer scientist at Georgia Tech, noticed that her 72-year-old mother is still very active and can walk for miles – but complained about climbing stairs. Karen wondered whether we could engineer a little boost into her step while climbing stairs.
Karen was inspired by an innovative lightweight ankle exoskeleton, designed by Steve Collins at Carnegie Mellon. The exoskeleton is worn like a brace on the ankle and reduces the energy required of the wearer during walking. On each step, the exoskeleton stores and then returns energy to the user through a clever use of a spring and a mechanical clutch.
On each step during walking, we use energy in our muscles to first brake our bodies and then propel ourselves forward. The ankle brace helps with both of these jobs. It assists with braking by stretching a spring, and then with push-off by releasing the spring, relieving the work done by muscles for both tasks.
But Karen knows that her mother, like most people, would not wear an ankle brace or special shoes just to help her get up the stairs. Could the stairs themselves be modified?
A key insight came when she talked to our colleague Young-Hui Chang at Georgia Tech. He pointed out that unlike level walking, climbing the stairs requires almost pure propulsion and no braking by our muscles, so no energy can actually be stored. Undaunted, Karen realized that even if energy can’t be stored when going up the stairs, it could be stored when descending, where our muscles are almost exclusively braking to slow our bodies against the pull of gravity.
Our muscles act as brakes when we go down the stairs, dissipating energy while lowering the body. When we go up the stairs, they act as motors, generating energy to lift the body. Yun Seong Song, CC BY-ND
That’s when she approached me with the idea of making stairs that themselves store energy as someone descends, and releases it back to the user on the way up. I thought the idea was crazy, but agreed to let Yun Seong Song, a talented mechanical engineer at Missouri University of Science and Technology who was a postdoctoral researcher in my lab at the time, work on the idea. Since Yun Seong has a lot of expertise building robots – particularly exoskeletons – we though he might be the perfect person to build and test Karen’s energy-recycling stairs.
Energy-recycling assistive stairs cushion on the way down and assist on the way up.
Similar to the energy-recycling ankle exoskeleton, springs are stretched when a person goes down the stairs, which has the added benefit of cushioning stair descent. In fact, one test subject said it felt like walking on pillows. We measured a 27 percent reduction in ankle braking torque of the trailing leg, which lowers the body going down the stairs. Going up the stairs, the tensioned springs are released with a timing that helps to push the trailing leg up when lifting the body, reducing the propulsive torque required by the knee of the leading leg by 37 percent.
When walking down the steps, energy is stored in a spring as the movable tread lowers under the weight of the user. The spring then latches in place, ready to release energy to the user during stair ascent. Yun Seong Song, CC BY-ND
While we tried out our prototype only on healthy young adults, with further development and testing, it could potentially benefit users with limited mobility. We suspect our energy-recycling assistive stairs could ease the knee joint pain that’s often a reason for not taking the stairs. ERAS might also help mitigate falls – a major hazard when going down the stairs because braking against gravity is challenging for many. Perhaps the greatest benefit of ERAS could be making stair descent easier and safer for those with limited muscle strength.
A cheap, efficient home option
And since the energy-recycling steps are modular and compact, they can be added to existing stairs without the expensive remodeling required to install an elevator or escalator. Because there are no motors, the energy-recycling assistive stairs also consume little power. In contrast to passively riding an elevator, our prototype requires users to actively participate in stair-climbing, which could help them retain their mobility.
Energy-recycling assistive stairs thus open the possibility for people to stay more active and live independently in their homes even as they lose mobility due to injury, aging or degenerative diseases of the musculoskeletal and nervous systems.
Lena Ting, Professor of Biomedical Engineering and Rehabilitation Medicine, Division of Physical Therapy, Emory University
Energy-recycling assistive stairs thus open the possibility for people to stay more active and live independently in their homes even as they lose mobility due to injury, aging or degenerative diseases of the musculoskeletal and nervous systems.