Science Friday

Jackson Water Woes, Giant Telescope Mirror, Shark Sex. March 12 2021, Part 1

March 12, 2021

What Went Wrong With Jackson, Mississippi’s Water?

Residents of Jackson, Mississippi have been dealing with a water crisis since a storm rolled through town on February 15th. The city’s water system was damaged, leaving thousands of residents without running water at home. People have relied on water distribution sites to get by, and even those who can still use their taps are on boil water notice. Impacted residents are largely low-income, and the limited access to water has raised worries about staying safe during the COVID-19 pandemic.

Even before this fiasco, Jackson’s water system was in need of a change. Boil water advisories were common, and many of the city’s pipes date back to the 1950s. Water service is expected to be restored this week, but getting the taps running again will just be a Band-Aid: A true overhaul would require millions, if not billions of dollars. Mississippi Public Broadcasting reporter Kobee Vance joins guest host John Dankosky to discuss what’s happening in Jackson, and why its infrastructure was particularly vulnerable to this crisis.

 


Spinning Glass To See The Stars

Last weekend, a giant furnace built under the east stands of the University of Arizona football stadium began to spin. That furnace contained some 20 tons of high-purity borosilicate glass, heated to 1,165 degrees C. As the glass melted, it flowed into gaps in a mold. The centrifugal force of the spinning furnace spread the material up the edges of the mold, forming the curved surface of a huge mirror, with a diameter of 8.4 meters.

The piece is just one of seven sections that will eventually form the 25-meter primary mirror of the Giant Magellan Telescope in Chile. It’s not a fast process—it will take several months to cool, and then another two years to measure, grind, and polish. When that’s complete, the surface of the mirror segment will be accurate to within twenty-five nanometers. Steward Observatory mirror polishing program project scientist Buddy Martin says that when it’s complete, the Giant Magellan Telescope should be ten times sharper than the Hubble Space Telescope—if it was positioned in Washington, DC, it would be able to make out a softball in the hand of a pitcher in San Francisco.

Martin talks with SciFri’s Charles Bergquist about the mirror production process, and the challenges of working with glass on massive scales. Watch a video and see photos of the process at scienefriday.com.

 


It’s Time To Rethink Shark Sex—With Females In Mind

Sharks, rays, and skates—all fish in the subclass Elasmobranchii—are a beautifully diverse collection of animals. One big way they differ is in how they reproduce. They lay eggs, like traditional fish, and let them mature in a select corner of the ocean. Or, they might let the eggs hatch inside their bodies. But they can also give live birth to pups gestated like mammals: with an umbilical cord and a placenta in a uterus.

It doesn’t end there. These fish, like many other members of the animal kingdom, have two uteruses. Females are capable of reproducing asexually, without help from a male. As genetic sequencing has advanced, researchers have been finding another curious pattern: Many litters of pups will have more than one father, a phenomenon known as multiple paternity.

Evolutionary ecologists seeking to explain why sharks would use this strategy of multiple paternity have hypothesized it’s one of convenience for females. In species with aggressive and competitive mating practices, like many sharks and rays, it’s possible females find it saves them precious resources to acquiesce to multiple males.

But what if there’s something in it for the female, and her likelihood of having successful, biologically fit offspring? That’s the question a team of researchers sought to answer in new research published in Molecular Ecology this month, where they asked what kinds of physiological mechanisms a female shark or ray might use to wield agency in her own reproduction. The researchers also write that a male-dominated field may be more likely to miss a female-driven reproductive strategy, and push for more study of female reproductive biology.

John Dankosky talks to the lead author on the research, Georgia Aquarium shark biologist Kady Lyons, about the vast wonderland of reproductive strategies in this fish subclass—and what a history of male-centered research may have missed.

 


What Next For The Fully Vaccinated?

In the U.S., vaccines have been rolling out since December. According to the Centers for Disease Control and Prevention, more than 95 million doses have been administered which equates to over 18% of the population. This week, the agency also put out guidelines for those who have been fully vaccinated.

Sophie Bushwick of Scientific American fills us in on those guidelines and also talks about research on the effectiveness of mask mandates and a headless sea slug.

 

 

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