Power companies channel electrons around using copper wires. As it turns out, certain bacteria appear to do something similar. In the absence of oxygen, a number of common soil bacteria species grow tiny nanowires, along which they push electrons to nearby rocks. This movement of the electrons produces energy, which the bacteria use to make ATP -- the molecule all cells use to power everything they do. However, this energy production strategy is rather unusual; outside of these species, most cells, including human cells, produce their energy using internal processes, not external ones.
"What the cell is doing is actually morphing a little bit," Mohamed El-Naggar, a physicist at the University of Southern California who led the new study, tells Popular Science. "It's extending its outer membrane in the shape of a long tube." Previously, scientists had thought bacterial nanowires were made of pili, hair-like appendages that are common on single-celled organisms.
"This solves a long-standing mystery about how exactly does the charge move on these structures," El-Naggar says. Bacterial cell membranes have proteins embedded in them called cytochromes, which—ta-da!—are known to pass electrons to one another. Pili don't have cytochromes. (Nevertheless, there's evidence that other species may truly use pili to make their nanowires, El-Naggar says.)
El-Naggar has studied nanowire-making bacteria for several years now. In 2012, Popular Science named him one of the Brilliant 10 young scientists of the year for his work. Studies like his could one day lead to bioelectric devices that combine both silicon components and biological ones. After all, if there are bacteria that are able to transfer electrons to rocks, then they could also transfer electrons to components in a circuit. Engineers are also trying to incorporate nanowire-making bacteria into fuel cells.
There's still plenty of work to do on both fronts. There's no guarantee bacterial fuel cells or circuits will be more efficient than the ones being used today. But the idea is that if biological circuits do work, "you kind of end up getting the best of both worlds," El-Naggar says. The resulting circuit could have both components that fix themselves and replicate themselves (from the bacteria) as well as super-precise components (the man-made parts).
El-Naggar and his team published their work today in the journal Proceedings of the National Academy of Sciences.
This legal doctrine asserts that people should be able to leave their past in the past. Although the concept has roots in centuries-old French law, the growth of the Web and social sharing in the last decade has prompted legal experts to reexamine it. The ease with which Google serves up a de facto profile of any private citizen is enough to make many people leery of how their lives look online. The ECJ ruling, however, is a major overcorrection. It could allow individuals to revise or censor their histories at will.
Google received more than 41,000 removal requests in the first four days it accepted them, and began deleting links in early July. “The court has handed Google a gavel and given it lower-court status,” says Meg Ambrose, assistant professor of international technology policy at Georgetown University. To help establish guidelines and processes for this new digital gray area, the company formed an advisory board that includes Wikipedia co-founder Jimmy Wales and former Spanish Data Protection Agency director José-Luis Piñar.The ease with which Google offers a profile of anyone makes many people leery of how their lives look online.
One likely suggestion from the committee: Make search results more timely and relevant. Google has been making those types of refinements for years; in 2011, for example, the company placed an increased value on timeliness. This June, it boosted the mobile-search rank of sites with designs responsive to mobile browsers—a revision that could bury outdated hits. Lesser-known search engines have pushed this idea even further. NowRelevant, for one, only shows results posted in the past 14 days.
Still, this doesn’t get to the root of the problem: How do we best deal with outdated content? Viktor Mayer-Schönberger, professor at the Oxford Internet Institute, who’s been called the godfather of the right to be forgotten, has suggested that publishers assign content-expiration dates based on the lifespan of the information’s relevance. He envisions a new profession focused on the proper handling of data—each company would employ one such handler, the same way it would have an accountant or office manager. In essence, he wants a set of standards that leave the decisions about how data is used to its publishers. This would curtail censoring from individuals guided only by self-interest, and eliminate the prospect of sweeping, arbitrary deletions by Google, which should never have been given final say to begin with.
This article originally appeared in the September 2014 issue of Popular Science.
Powered by a pusher propeller, covered in pixel camouflage, and furnished with stadium-seating for its two crew members, the Advanced High Performance Reconnaissance and Surveillance Aircraft (AHRLAC) looks like an alternate history version of a World War I fighter. The result of a collaboration between South Africa's Aerosud aviation firm and the Paramount Group, the AHRLAC is designed as a cheap alternative to the big name in military surveillance right now: drones.
The AHRLAC is designed for flexible roles, depending on how it's equipped. These range from surveillance to light attack, which could make it a useful tool for border patrol, some forms of counter-insurgency warfare, and, perhaps most relevantly, anti-poaching activities. The pusher propeller design -- in which the propellers are mounted behind their respective engines -- helps the plane fly slowly, an important task for surveillance aircraft. (Pusher propellers were also used on the infamous Predator drone.) AHRLAC's maximum speed is about 310 mph, and it can fly for up to 7.5 hours. It's made to carry everything from surveillance cameras and radar to rockets, flares, and some missiles.
The manufacturers boast that AHRLAC is the "first ever aircraft to be fully designed and developed in Africa," though that claim is contested. Several features make it well suited for rural use: A short takeoff distance of only 1,800 feet and high wings mean it can even take off from fields with some underbrush.
Watch a video of it below:
Each month at Popular Science, we sift through a mountain of new products—everything from gadgets and tools to books and movies—so that you don't have to.
View the gallery below to see 10 of our favorite things hitting the shelves (or are already on them) this September.
This article orignially appeared in the September 2014 issue of Popular Science.
I was recently alerted to a video showing a praying mantis attacking a hummingbird.
"Wait," I thought, "mantises can catch hummingbirds?" This seemed unlikely to me, due to the size difference. I searched and found several videos purporting to show a hummingbird "murdered" by a mantis, or something similar. Almost all of these videos presented a mantis holding onto a hummingbird and appearing to eat it -- but none of them showed the moment of attack itself.
I kept looking and finally found this video which does show a mantis successfully catching a hummingbird and beginning to gnaw on it. Unfortunately, it's impossible to say with 100 percent certainty that the mantis would have won the match, because the maker of the video decided to flick the mantis, sending the insect and its avian prey tumbling. (Go ahead and skip to 0:36 to see the mantis strike.)
But, after a bit of research, it seems pretty clear that mantises are capable of catching hummingbirds. In this 1982 study in Biological Reviews, the authors report that praying mantises can indeed catch small hummingbirds. "Praying mantises reach a length of 98 mm [3.9 inches] and may feed on small birds," the authors write. However, "the actual observations in the literature are inconclusive as the captured birds were ultimately released by concerned ornithologists," they continued, somewhat perplexingly, since it is generally frowned upon for scientists to intervene in the lives of the animals they study.
It makes more sense if you consider that these ornithologists -- all bird lovers, no doubt -- likely observed these things in passing and weren't specifically studying avian-insect interactions. I wonder if a mantis specialist had witnessed this: What might he or she do?
Here's a video of a mantis catching a hummingbird, and promptly falling off the bird feeder, perhaps to savor its bird-treat on the ground... or maybe not. (Jump to 0:46).
There's another account (albeit second-hand) in The Wilson Journal of Ornithology of a ruby-throated humming bird being caught by a praying mantis. But this man also helped the hummingbird escape. Another 1949 anecdote from The Auk records a praying mantis catching a hummingbird, and a more modern piece from Birdwatcher's Digest recounts one bird lover's tail of the same thing, with photos. This may be the only account I've seen where the author/witness didn't try to free the bird.
It all goes to show that praying mantises are not to be toyed with, at least by creatures that are approximately mantis-sized or smaller. These insects have also been known to attack and eat small mice.
In celebration of the mantis, here is "True Facts About The Mantis," which is at least mostly factual.
Battery life: Seven days
Charging: Qi wirelessHow are breath and emotion connected?
Vagal Tone: The term refers to activity of the vagus nerve—a cranial nerve that originates in the brain stem and connects with and regulates the resting states of many of the body’s organs, including the heart. Since vagal tone cannot be measured directly, researchers assess other biological processes, such as respiratory sinus arrhythmia, or changes in heart rate during a breathing cycle. During stressful situations, heart rate varies more wildly.
This article originally appeared in the September 2014 issue of Popular Science.
Mars almost definitely has water below its surface, and it’s possible that it might have life there too -- buried deep in the soil, where it’s protected from dryness, radiation and temperature extremes. Unfortunately, NASA doesn’t seem too interested in looking for it, preferring to look for "conditions" that might support life instead. But a group of aerospace and robotics engineers -- many of whom work for NASA, and one of whom even operates the Curiosity rover -- think NASA should be going with a more direct approach, and they're taking matters into their own hands.
“While current NASA missions are looking for evidence of past life, no NASA mission is planned to look for current life,” they write on their website. “We believe this is a mistake. To find life on Mars, we actually need to look for life on Mars.”
Part of the challenge of looking for life on Mars has been in designing the right equipment to dig for it. Curiosity was the first robot to drill into Martian soil. That was in 2013, and the hole was two inches deep. To search for life, robots have to dig a lot deeper than that. But scientists are struggling to come up with a design small enough to fit onto a rover yet robust enough to survive being pelleted with dust and radiation.
So, rather than sending giant drills to Mars, the scientists behind the ExoLance Indiegogo campaign are suggesting we dig in with big lawn darts instead.
The concept is fairly simple by NASA standards. ExoLance could theoretically piggyback on another mission to Mars, and as the spacecraft enters the Martian atmosphere, a dart dispenser (named “Quiver”) separates from the ride. As it falls to the ground at supersonic speeds, it drops the “arrows," which bury themselves 3 to 6 feet into the Martian soil."No NASA mission is planned to look for current life. We believe this is a mistake. To find life on Mars, we actually need to look for life on Mars."
As an arrow burrows, its nose separates from its back end to expose the life-detection equipment pack inside. This would be a metabolic test that can distinguish between living and non-living chemistry, the ExoLance team says. (Alternate strategies have proposed looking for DNA or ribosomal RNA.) Meanwhile, the hind end of the arrow stays above the surface, to communicate with an orbiter about the scientific findings.
Other scientists have come up with concepts similar to ExoLance. Last year one British team successfully fired darts at an 11-ton block of ice, at a speed of 760 miles an hour, to test whether the method was viable to hunt for life on icy moons like Europa and Enceladus.
Through crowdfunding, the ExoLance scientists are trying to raise $250,000 to build prototypes that they will then test by dropping them out of an airplane in the Mojave Desert. Phase II (which requires a lot more funding) will focus on developing the life-detection equipment.
“Once the concept is sufficiently tested and we have proven the viability of the mission concept, we will approach NASA, other space agencies, and potential commercial providers to carry ExoLance on one or more future Mars missions,” their website says.
The team has many challenges ahead of them, which they note on their campaign site. For one, the project will likely cost between $1 and $10 million overall. They’ll need to make sure the arrow penetrates to just the right depth; they’ll need a reliable power source; they’ll need to secure a chance to piggyback on another mission; and they’ll need to keep the payload as small and lightweight as possible to avoid extra costs.
The implications of looking for life on Mars are potentially huge. If we discover microorganisms there, it could rewrite biology, evolution, and history. It could also mean that life on Earth preceded life on Mars, or vice versa. Or, if we find nothing, at least it'll be a clear answer.