Month: June 2020

Enlarge / UC graduate student Brian Lane climbs out of the Perdido Reservoir. (credit: Photo/Nicholas Dunning)

For centuries, Tikal was a bustling Maya city in what is now northern Guatemala. But by the late 800s CE, its plazas and temples stood silent, surrounded by mostly abandoned farms. A recent study suggests a possible explanation for its decline: mercury and toxic algal blooms poisoned the water sources that should have carried the city through dry seasons.

Tikal’s Maya rulers built the city’s reservoirs to store water from rain and runoff during the winter months. The pavement of the large plazas in the heart of the city tilted slightly, helping funnel rainwater into the reservoirs. Over the centuries, dust and litter settled into the bottom of the reservoirs, too, providing a record of what the environment around Tikal was like—and what was washing into the city’s water supply. University of Cincinnati biologist David Lentz and his colleagues sampled layers of sediment dating back to the mid-800s, and they found that two of Tikal’s central reservoirs would have been too polluted to drink from.

An X-ray fluorescence spectrometer (which identifies the chemicals in a sample based on how they react to being zapped with an X-ray light) revealed that the sediment on the bottom of the reservoirs was laced with dangerous amounts of mercury. Lentz and his colleagues also found ancient DNA from blue-green algae, or cyanobacteria, which can produce deadly toxins.

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  A model shows off a prototype form factor for a holographic VR display. [credit: Facebook Research ]

For all the advancements in virtual reality technology in recent years, one major factor still holding the space back is the size and relative discomfort of current headset design. Even the most compact and comfortable VR headsets today still resemble something like a cross between ski goggles and a motorcycle helmet, requiring massive headstraps to secure a heavy display that protrudes multiple inches away from the face. Reference designs for "eyeglasses" style VR displays help a bit, but they still look like coke-bottle spectacles from a steampunk cosplay event (and provide a limited field of view, to boot).

Now, researchers at Facebook Reality Labs are using holographic film to create a prototype VR display that looks less like ski goggles and more like lightweight sunglasses. With a total thickness less than 9mm—and without significant compromises on field of view or resolution—these displays could one day make today's bulky VR headset designs completely obsolete.

In the newly published ACM Siggraph paper Holographic Optics for Thin and Lightweight Virtual Reality, researchers Andrew Maimone and Junren Wang detail the optics behind their lightweight prototype. The key to the thinness is a series of flat, polarized films that use a "pancake optics" light-folding technique to reflect the displayed image multiple times in a small space.

Enlarge / CCTV security guard in the mall building.

Detroit's police chief admitted on Monday that facial recognition technology used by the department misidentifies suspects about 96 percent of the time. It's an eye-opening admission given that the Detroit Police Department is facing criticism for arresting a man based on a bogus match from facial recognition software.

Last week, the ACLU filed a complaint with the Detroit Police Department on behalf of Robert Williams, a Black man who was wrongfully arrested for stealing five watches worth $3,800 from a luxury retail store. Investigators first identified Williams by doing a facial recognition search with software from a company called DataWorks Plus. Under police questioning, Williams pointed out that the grainy surveillance footage obtained by police didn't actually look like him. The police lacked other evidence tying Williams to the crime, so they begrudgingly let him go.

Now Vice's Jason Koebler reports that Detroit Police Chief James Craig acknowledged the flaws with its facial recognition software at a Monday event.

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  Base camp of the National Geographic crew, illuminated below Everest. [credit: Renan Ozturk/National Geographic ]

Edmund Hillary and Sherpa mountaineer Tenzing Norgay made climbing history when they became the first men to successfully summit Mount Everest on May 29, 1953. But there's a chance that someone may have beaten them to the summit back in 1924: a British mountaineer named George Leigh Mallory and a young engineering student named Andrew "Sandy" Irvine. The two men set off for the summit in June of that year and disappeared—two more casualties of a peak that has claimed over 300 lives to date.

Lost on Everest is a new documentary from National Geographic that seeks to put to rest the question of who was first to the summit once and for all. The gripping account follows an expedition's attempt to locate Irvine's body (lost for over 95 years) and hopefully retrieve the man's camera—and photographic proof that the two men reached the summit.

NatGeo is also premiering a second companion documentary, Expedition Everest, narrated by actor Tate Donovan (MacGyver, Man in the High Castle), following an international team that included multiple scientists as they trek up the mountain. Along the way, team geologists collected sediment samples from the bottom of a Himalayan lake; biologists surveyed the biodiversity at various elevations to track how plants, animals, and insects are adapting to a warming climate; and climate scientists collected ice cores from the highest elevation to date to better understand glacier evolution. Finally, the team installed the world's highest weather station in Everest's infamous "death zone," above 26,000 feet, to gather real-time data on weather conditions at that altitude.

Welcome to the pilot episode of "Human Interface," a new series we're kicking off wherein we take you up close and personal with complex systems and have an expert explain what all the buttons and switches do. "Pilot episode" is particularly appropriate here, because we're kicking off the series with a look at a McDonnell Douglas F-15C Eagle, one of the world's most famous air superiority fighters. The F-15C and its variants are in service with multiple air forces around the world, including the United States, Japan, and Israel, and the aircraft has an outstanding combat record—across all its deployments and operators, air-superiority F-15s like the F-15C have racked up more than 100 air-to-air kills and zero losses.

Before the coronavirus made everything crazy, we were able to score some time with an F-15C on the flight line at Fresno Air National Guard Base in California. Our tour guide was Air Force pilot Colonel Andrea Themely, who retired in 2018 after serving for 23 years. Col. Themely has about 3,400 hours piloting high-performance jet fighters and about 1,100 hours specifically in F-15Cs, and her last post was commanding the Air Force's 80th Flying Training Wing.

Buttons, buttons everywhere...

As I found out firsthand a few years ago in the Navy's F/A-18 simulator at NAS Oceana, a fourth-generation jet fighter like the F-15C is typically equipped with a mish-mash of '70s- and '80s-era screens and buttons, with other more current-looking '00s-era controls shoehorned into the corners. This reflects the fact that fighters like the F-15C and its contemporaries are mostly products of the 1970s, with more modern improvements bolted on over time.