Posted: 11 Jan 2010 11:08 AM PST
The long-distance scientific recordings of the blast wave from the first hydrogen bomb test have been rediscovered in a formerly classified safe at Columbia University.
On November 1, 1952, physicists created the second fusion explosion the solar system has ever known. The first had occurred around 4.5 billion years ago and ignited the on-going fusion reaction in the sun. The second, the Ivy Mike experiment, was shorter lived and detonated on an atoll in the South Pacific. This ten-megaton blast was five times more powerful than all the explosives in World War II combined, including the nuclear-fission bombs dropped on Hiroshima and Nagasaki.
The blast set off a low-frequency sound wave beneath the human hearing range, which was recorded halfway around the world at special listening stations designed by the Lamont Geological Observatory in Palisades, New York for monitoring just such an event. The microbarographs measured changes in atmospheric pressure, and were particularly well-suited to detecting a nuclear explosion. As the wave passed, the ink-filled needles of the instruments scribbled on paper rolling around a drum.
Then, in preparation for retirement in 2008, Lamont's former security director Ray Long began cleaning out the safe. Recognizing there might be something to the recordings, he contacted Paul Richards, a seismologist and specialist in nuclear-test tracking. Richards immediately knew the measurements "were of historic importance."
If they couldn't be declassified, they would have to be sent to the U.S. Air Force, which originally classified them, or destroyed. So, Richards tracked down the right people in the Air Force and asked them to declassify the documents so that they could by preserved for posterity.
"They had the bureaucratic problem that there was no obvious indication on how to do it," Richards said. "They were very helpful, but it took a while."
Now, finally, more than 57 years after the ink was first laid on the paper, the recordings can be seen by all.
At first, the Lamont scientists working on the problem of remote nuclear-detonation detection thought they might need to get measurements from high in the atmosphere. So they sent balloons up with recording equipment. As an odd historical footnote, this research program may have launched the long-standing rumors of something strange going on near Roswell, New Mexico, when one of its stations crashed in the area.
"The program was called Project Mogul, and its goal, set by a postwar America wary of losing its atomic monopoly, was to search high in the atmosphere for weak reverberations from nuclear-test blasts half a world away," journalist William Broad explained in a 1994 New York Times article. "The debris, found near Roswell, New Mexico, was a smashed part of the program's balloons, sensors and, of most consequence to the growth of spaceship theories, radar reflectors made of thin metal foil. At the time, the Air Force said the wreckage was that of a weather balloon, a white lie."
Over the years, scientists realized that they could use ground-based stations and didn't need high-flying balloons. For years, microbarographs were used to measure nuclear weapons tests as they grew ever bigger, up to the largest test ever by the Soviet Union, which topped 50 megatons, a thousand times more powerful than the bombs dropped on Hiroshima and Nagasaki.
Satellites largely took over weapons test monitoring in the 1960s within the United States and Soviet Union. However, with the signing of the Comprehensive Nuclear Test Ban Treaty in 1994, cheap, easy-to-deploy microbarograph stations were deployed at dozens of locations across the world from Piñon Flats in California to Antananarivo, Madagascar.
Image: 1. Lamont-Doherty Earth Observatory/Kim Martine. 2. Video of Ivy Mike experiment.
Posted: 11 Jan 2010 07:11 AM PST
SEATTLE — It's easy being green for a sea slug that has stolen enough genes to become the first animal shown to make chlorophyll like a plant.
Shaped like a leaf itself, the slug Elysia chlorotica already has a reputation for kidnapping the photosynthesizing organelles and some genes from algae. Now it turns out that the slug has acquired enough stolen goods to make an entire plant chemical-making pathway work inside an animal body, says Sidney K. Pierce of the University of South Florida in Tampa.
The slugs can manufacture the most common form of chlorophyll, the green pigment in plants that captures energy from sunlight, Pierce reported January 7 at the annual meeting of the Society for Integrative and Comparative Biology. Pierce used a radioactive tracer to show that the slugs were making the pigment, called chlorophyll a, themselves and not simply relying on chlorophyll reserves stolen from the algae the slugs dine on.
"This could be a fusion of a plant and an animal — that's just cool," said invertebrate zoologist John Zardus of The Citadel in Charleston, S.C.
Microbes swap genes readily, but Zardus said he couldn't think of another natural example of genes flowing between multicellular kingdoms.
Pierce emphasized that this green slug goes far beyond animals such as corals that host live-in microbes that share the bounties of their photosynthesis. Most of those hosts tuck in the partner cells whole in crevices or pockets among host cells. Pierce's slug, however, takes just parts of cells, the little green photosynthetic organelles called chloroplasts, from the algae it eats. The slug's highly branched gut network engulfs these stolen bits and holds them inside slug cells.
Some related slugs also engulf chloroplasts but E. chlorotica alone preserves the organelles in working order for a whole slug lifetime of nearly a year. The slug readily sucks the innards out of algal filaments whenever they're available, but in good light, multiple meals aren't essential. Scientists have shown that once a young slug has slurped its first chloroplast meal from one of its few favored species of Vaucheria algae, the slug does not have to eat again for the rest of its life. All it has to do is sunbathe.
But the chloroplasts need a continuous supply of chlorophyll and other compounds that get used up during photosynthesis. Back in their native algal cells, chloroplasts depended on algal cell nuclei for the fresh supplies. To function so long in exile, "chloroplasts might have taken a go-cup with them when they left the algae," Pierce said.
There have been previous hints, however, that the chloroplasts in the slug don't run on stored-up supplies alone. Starting in 2007, Pierce and his colleagues, as well as another team, found several photosynthesis-related genes in the slugs apparently lifted directly from the algae. Even unhatched sea slugs, which have never encountered algae, carry "algal" photosynthetic genes.
At the meeting, Pierce described finding more borrowed algal genes in the slug genome for enzymes in a chlorophyll-synthesizing pathway. Assembling the whole compound requires some 16 enzymes and the cooperation of multiple cell components. To see whether the slug could actually make new chlorophyll a to resupply the chloroplasts, Pierce and his colleagues turned to slugs that hadn't fed for at least five months and had stopped releasing any digestive waste. The slugs still contained chloroplasts stripped from the algae, but any other part of the hairy algal mats should have been long digested, he said.
After giving the slugs an amino acid labeled with radioactive carbon, Pierce and his colleagues identified a radioactive product as chlorophyll a. The radioactively tagged compound appeared after a session of slug sunbathing but not after letting slugs sit in the dark. A paper with details of the work is scheduled to appear in the journal Symbiosis.
Zardus, who says that he tries to maintain healthy skepticism as a matter of principle, would like to hear more about how the team controlled for algal contamination. The possibilities for the borrowed photosynthesis are intriguing though, he says. Mixing the genomes of algae and animals could certainly complicate tracing out evolutionary history. In the tree of life, he said, the green sea slug "raises the possibility of branch tips touching."
"Bizarre," said Gary Martin, a crustacean biologist at Occidental College in Los Angeles. "Steps in evolution can be more creative than I ever imagined."
Image: Nicholas E. Curtis and Ray Martinez
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