Bill passed requiring drug tests for welfare recipients.
Friday, December 13, 2013
Universe May Have Been Around Since Forever, According to Rainbow Gravity Theory
on
Behind the scenes of the Big Bang is Einstein’s theory of general relativity. But there’s a problem. Einstein’s theory is at odds with quantum mechanics, the theory of tiny particles. Rainbow gravity was proposed to reconcile the two, and if it were correct, the universe would have no beginning—there is no big treasure at the foot of this “rainbow” because the “rainbow” universe goes back forever.
According to the theory of rainbow gravity, the force of gravity would split a source's electromagnetic radiation into different wavelengths, just like a prism does with visible white light.
Why is it called rainbow gravity? Because according to the theory, gravity becomes a cosmological prism that can separate different colors of light. Our eyes can’t see that—when we gaze longingly into the night sky, the stars’ white light appears to have streamed smoothly to our eyes. If rainbow gravity is right though, light’s path through outer-space may be more like the famous Pink Floyd poster, where the different colors become spread apart.So, why don’t we see rainbow stars? Clara Moskowitz, writing for Scientific American, tells us more:
The effects would usually be tiny, so that we wouldn’t notice the difference in most observations of stars, galaxies and other cosmic phenomena. But with extreme energies, in the case of particles emitted by stellar explosions called gamma-ray bursts, for instance, the change might be detectable. In such situations photons of different wavelengths released by the same gamma-ray burst would reach Earth at slightly different times, after traveling somewhat altered courses through billions of light-years of time and space. “So far we have no conclusive evidence that this is going on,” says Giovanni Amelino-Camelia, a physicist at the Sapienza University of Rome who has researched the possibility of such signals. Modern observatories, however, are just now gaining the sensitivity needed to measure these effects, and should improve in coming years.Rainbow gravity may just be an illusion, a pretty idea that makes science a bit more colorful. But soon we may find out if we’re living in an infinitely old rainbow universe.
Learn more about other alternative theories in "Fabric of the Cosmos: Universe or Multiverse?"
New York: The Front of All Fracking Opposition
Tom ShepstoneShepstone Management Company, Inc.
Catskill Citizens for Safe Energy is again using Pennsylvania residents as foils in a campaign against fracking in New York, the font of fracking opposition.
Sometimes, I fear readers will think this site is too New York centric, but the truth is this; the bulk of the fracking opposition, whether it takes place in Colorado, California, Texas or the UK (where Dimock is a well known name) is, ultimately, all about New York. It is primarily New York money that funds most anti-fracking campaigns. It is New York based organizations who lead the effort. It is New York activists who gin up the controversy wherever it occurs. No further proof of this is needed than the continued exploitation of Pennsylvania residents, both pro and con, by a group known as Catskill Citizens for Safe Energy.
Who is this Catskill Citizens for Safe Energy? Well, it’s mostly a collection of fairly well-to-do New York City retirees, semi-retirees and trust-funders who have built second homes or retirement homes in the Upper Delaware valley region of Sullivan County, New York. Their address is Fremont Center, New York, where actress Debra Winger resides when she’s not in Manhattan. Mark Rufalo lives nearby and Jennifer Lopez had a place down the road.
The prime mover in the group is a fellow named Bruce Ferguson, a retired 60 Minutes producer. It maintains an extensive website and claims to have 1,200 members. Other directors of the organization include Jannette Barth, the art economist who poses as a fracking expert and other close friends of Ferguson. It is registered as a charity and spent just shy of $150,000 in 2012 fighting fracking, according to its 990 return. Like so many of these organizations, it is inherently political in nature, even claiming one of its purposes to facilitate the contacting of legislators on pending legislation. Yet, it also claims to make no political expenditures. Such is the abuse of the tax-exempt status enjoyed by these groups.
This isn’t the only abuse. Catskill Citizens also, with the help of a disreputable group called the Civil Society Institute, funded by George Soros and others, mailed New Yorkers 190,000 copies of one of the trashiest anti-gas pieces we’ve ever scene. It can only be described as a pack of lies and was purely political, being aimed at encouraging New York towns to pass fracking moratoriums. Catskill Citizens also worked with Debra Winger on a failed campaign to get second owners to register to vote in upstate New York towns and take them over on behalf of their gentry class, kicking out the locals and sued some of these towns in an attempt to bully them.
Catskill Citizens also loves using Pennsylvania residents as foils for its New York campaign. Two years ago, the organization funded an infamous billboard in Dimock, an hour away from its own base of operations. That billboard showed a dirty pitcher of water against a background of chemical names, suggesting, with no basis in fact, these chemicals had been introduced by fracking and had made the water brown. It was all a fabrication and later testing by the EPA proved it. There was nothing in the water making it unsafe or that could be connected to fracking operations and when Phelim McAleer, producer of FrackNation, asked Craig Sautner to produce dirty water from his faucet, he couldn’t. It was all another fantastic lie engendered and repeated by Catskill Citizens and others for the sole purpose of keeping fracking out of New York.
Now, they’re at it again. We just received a copy of an e-mail invitation from trial lawyer representative Craig Stevens about a rally being organized by Catskill Citizens in Franklin Forks, Pennsylvania on Monday in an attempt to stop WPX Energy from removing water buffaloes from homes placed there before the Commonwealth’s Department of Environmental Protection (DEP) determined methane problems in some water wells had not been caused by gas drilling. Labeled “A Grinch Christmas Christmas in Franklin Forks, PA?” the e-mail includes a distorted history of events that takes issue with the DEP findings and says to contact Catskill Citizens for more information.
The Mannings probably could have had their well repaired long ago as a courtesy from the gas company, but were convinced to go for the big kill and sue, despite overwhelming evidence drilling had nothing to do with it. They have been encouraged to give continued life to a story that only serves others’ objectives, reducing themselves to role-playing in juvenile acts of attention seeking by the likes of Vera Scroggins and Catskill Citizens.
We see this routine played out over and over again as New York based groups seek out event opportunities everywhere they can in the world to generate controversy and negative press for fracking. Plainly put, they’re simply users. When the blood is sucked out of this little controversy, they’ll simply move onto the next and the Mannings won’t even rise to the level of distant memory for them. If they really cared, they’d raise the money to fix the Manning water well, which only has a mechanical problem caused by flooding a few years ago. A solution isn’t what’s desired, however, by these groups. They want the issue and they created the box the Mannings are now in, having encouraged them to sue.
This takes us back to the last time Catskill Citizens and its New York allies interjected themselves into a Susquehanna County matter. That involved the Sautners, who were exploited in a very similar way by trial lawyers and New York fractivists before EPA testing brought the whole charade to a merciful end. Who can forget the scene in FrackNation where Julie Sautner, while threatening Phelim McAleer with the fact she had a gun, said she’d sic the NRDC on him? She obviously thought the NRDC was there for her when needed and, no doubt, had the same view of Catskill Citizens, which gave her the billboard screen, after it was taken down, to place on her roof. Does anyone think the NRDC would take her call today?
Nothing is stopping the NRDC from still talking about the Sautners and their case but their name has, nonetheless, disappeared into that dustbin of history. They are no longer useful foils for the New York campaign and so they’ve been sloughed off. That fate awaits the Mannings as well. It will all end with a dull and imperceptible thud when they are no longer useful in supposedly demonstrating the dangers of fracking to New Yorkers. Catskill Citizens, NRDC, et al will then seek out new foils, because New York is the font of all fracking opposition.
Politically Motivated "Environmental" Groups and Democratic Allies on KeystoneXL
By Kate Sheppard
Rep. Raul Grijalva (D-Ariz.), the ranking member of the House Natural Resources Committee, took the lead on the letter expressing "serious concerns about conflicts of interest" related to the consulting firm that authored the most recent environmental impact analysis, which downplayed environmental and safety concerns. As The Huffington Post has previously reported, after contractor Environmental Resources Management wrote the report on Keystone XL, it was discovered that some of the consultants involved in the analysis had done previous work for the company seeking to build the pipeline, TransCanada. They had also done work for a TransCanada subsidiary and for other oil companies that could benefit from the pipeline's construction. Documents released via a Freedom of Information Act Request showed that the company had not disclosed the previous work in its conflict of interest statement.
ERM's supplemental environmental impact statement, released last March, found that the environmental effects of the pipeline are "expected to be rare and relatively small." A final version of the report has not yet been released, but will inform the State Department's ultimate decision on the pipeline. Because the proposed 1,600-mile pipeline from Alberta, Canada to Texas crosses an international border, State will make the call on whether or not it gets built.
Environmental groups asked the State Department's Office of Inspector General to look into whether the contractors' previous work for TransCanada should have been considered a conflict of interest. The IG's analysis is still underway. Doug Welty, a spokesman for the IG's office, told The Huffington Post Thursday that his office expects to release the report at the end of January, sooner than the previous estimate of late February.
The members of Congress wrote Thursday that it "would be unwise and premature" for the State Department to release a final environmental impact analysis from ERM while the investigation is ongoing. The letter also accuses the company of "lying to federal officials about its ties to TransCanada and over a dozen oil companies with a direct stake in whether or not Keystone XL gets approved." From the letter:
The lawmakers urged the White House to wait for the outcome of this latest investigation before making any decisions on the pipeline. "If the allegations that ERM lied to the Department of State about its conflicts of interest turn out to be true the Department of State must conduct a new [environmental impact statement] that is not tainted by conflicts of interest," they wrote.
Democrats Ask Obama To Postpone Keystone XL Decision Amid Conflict Of Interest Probe
WASHINGTON –- Twenty-five House Democrats sent a letter to President Barack Obama on Thursday urging him to delay a decision on Keystone XL until the State Department's Inspector General finishes investigating the contractor that completed the environmental analysis of the proposed pipeline.
Rep. Raul Grijalva (D-Ariz.), the ranking member of the House Natural Resources Committee, took the lead on the letter expressing "serious concerns about conflicts of interest" related to the consulting firm that authored the most recent environmental impact analysis, which downplayed environmental and safety concerns. As The Huffington Post has previously reported, after contractor Environmental Resources Management wrote the report on Keystone XL, it was discovered that some of the consultants involved in the analysis had done previous work for the company seeking to build the pipeline, TransCanada. They had also done work for a TransCanada subsidiary and for other oil companies that could benefit from the pipeline's construction. Documents released via a Freedom of Information Act Request showed that the company had not disclosed the previous work in its conflict of interest statement.
ERM's supplemental environmental impact statement, released last March, found that the environmental effects of the pipeline are "expected to be rare and relatively small." A final version of the report has not yet been released, but will inform the State Department's ultimate decision on the pipeline. Because the proposed 1,600-mile pipeline from Alberta, Canada to Texas crosses an international border, State will make the call on whether or not it gets built.
Environmental groups asked the State Department's Office of Inspector General to look into whether the contractors' previous work for TransCanada should have been considered a conflict of interest. The IG's analysis is still underway. Doug Welty, a spokesman for the IG's office, told The Huffington Post Thursday that his office expects to release the report at the end of January, sooner than the previous estimate of late February.
The members of Congress wrote Thursday that it "would be unwise and premature" for the State Department to release a final environmental impact analysis from ERM while the investigation is ongoing. The letter also accuses the company of "lying to federal officials about its ties to TransCanada and over a dozen oil companies with a direct stake in whether or not Keystone XL gets approved." From the letter:
The Department of State apparently overlooked these conflicts when it accepted Environmental Resources Management’s (ERM) bid to perform the analysis. Because of the seriousness of the conflicts and because of allegations that ERM lied to the Department of State to get the contract, we believe no EIS from the company – draft or final – should be accepted by the administration before these issues are resolved.The IG's office had already looked into conflict of interest concerns regarding another contractor, Cardno Entrix, after environmental advocates pointed out that the company had done quite a bit of previous work for TransCanada. That IG report concluded that hiring Cardno Entrix had not created an actual conflict of interest, but it dinged the State Department for failing to independently evaluate the contractor's claim that it had no conflicts and for "accepting them at face value."
The lawmakers urged the White House to wait for the outcome of this latest investigation before making any decisions on the pipeline. "If the allegations that ERM lied to the Department of State about its conflicts of interest turn out to be true the Department of State must conduct a new [environmental impact statement] that is not tainted by conflicts of interest," they wrote.
Thursday, December 12, 2013
Universe Really Is a Hologram According to New Simulations
A 10-dimensional theory of gravity makes the same predictions as standard quantum physics in fewer dimensions
Image: Astronomy Picture of the Day
A team of physicists has provided some of the clearest evidence yet that our Universe could be just one big projection.
Maldacena's idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing—and because it solved apparent inconsistencies between quantum physics and Einstein's theory of gravity. It provided physicists with a mathematical Rosetta stone, a "duality," that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa. But although the validity of Maldacena's ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive.In 1997, theoretical physicist Juan Maldacena proposed that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity.
In one paper, Hyakutake computes the internal energy of a black hole, the position of its event horizon (the boundary between the black hole and the rest of the Universe), its entropy and other properties based on the predictions of string theory as well as the effects of so-called virtual particles that continuously pop into and out of existence. In the other3, he and his collaborators calculate the internal energy of the corresponding lower-dimensional cosmos with no gravity. The two computer calculations match.In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true.
“It seems to be a correct computation,” says Maldacena, who is now at the Institute for Advanced Study in Princeton, N.J., and who did not contribute to the team's work.
Regime change
The findings “are an interesting way to test many ideas in quantum gravity and string theory”, Maldacena adds. The two papers, he notes, are the culmination of a series of articles contributed by the Japanese team over the past few years. “The whole sequence of papers is very nice because it tests the dual [nature of the universes] in regimes where there are no analytic tests.”
“They have numerically confirmed, perhaps for the first time, something we were fairly sure had to be true, but was still a conjecture—namely that the thermodynamics of certain black holes can be reproduced from a lower-dimensional universe,” says Leonard Susskind, a theoretical physicist at Stanford University in California who was among the first theoreticians to explore the idea of holographic universes.
Neither of the model universes explored by the Japanese team resembles our own, Maldacena notes. The cosmos with a black hole has ten dimensions, with eight of them forming an eight-dimensional sphere. The lower-dimensional, gravity-free one has but a single dimension, and its menagerie of quantum particles resembles a group of idealized springs, or harmonic oscillators, attached to one another.
Nevertheless, says Maldacena, the numerical proof that these two seemingly disparate worlds are actually identical gives hope that the gravitational properties of our Universe can one day be explained by a simpler cosmos purely in terms of quantum theory.
Image: Astronomy Picture of the Day
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
Maldacena's idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing—and because it solved apparent inconsistencies between quantum physics and Einstein's theory of gravity. It provided physicists with a mathematical Rosetta stone, a "duality," that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa. But although the validity of Maldacena's ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive.In 1997, theoretical physicist Juan Maldacena proposed that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity.
In one paper, Hyakutake computes the internal energy of a black hole, the position of its event horizon (the boundary between the black hole and the rest of the Universe), its entropy and other properties based on the predictions of string theory as well as the effects of so-called virtual particles that continuously pop into and out of existence. In the other3, he and his collaborators calculate the internal energy of the corresponding lower-dimensional cosmos with no gravity. The two computer calculations match.In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true.
“It seems to be a correct computation,” says Maldacena, who is now at the Institute for Advanced Study in Princeton, N.J., and who did not contribute to the team's work.
Regime change
The findings “are an interesting way to test many ideas in quantum gravity and string theory”, Maldacena adds. The two papers, he notes, are the culmination of a series of articles contributed by the Japanese team over the past few years. “The whole sequence of papers is very nice because it tests the dual [nature of the universes] in regimes where there are no analytic tests.”
“They have numerically confirmed, perhaps for the first time, something we were fairly sure had to be true, but was still a conjecture—namely that the thermodynamics of certain black holes can be reproduced from a lower-dimensional universe,” says Leonard Susskind, a theoretical physicist at Stanford University in California who was among the first theoreticians to explore the idea of holographic universes.
Neither of the model universes explored by the Japanese team resembles our own, Maldacena notes. The cosmos with a black hole has ten dimensions, with eight of them forming an eight-dimensional sphere. The lower-dimensional, gravity-free one has but a single dimension, and its menagerie of quantum particles resembles a group of idealized springs, or harmonic oscillators, attached to one another.
Nevertheless, says Maldacena, the numerical proof that these two seemingly disparate worlds are actually identical gives hope that the gravitational properties of our Universe can one day be explained by a simpler cosmos purely in terms of quantum theory.
Cold War Bomb Testing Is Solving Biology’s Biggest Mysteries
on
David Strumfels' Comment: I t is often amazing how much good can come from things that are generally (and rightfully) regarded as evil.
Kirsty Spalding was one of the scientists who doubted that assessment. Spalding, once a postdoc at the Karolinska Institute in Stockholm, Sweden and now a professor there, knew there were tantalizing hints that the adult hippocampus—a seahorse-shaped region deep in the brain that is important for memory and learning—could regenerate neurons. But without knowing exactly when each neuron was created, scientists couldn’t say with any certainty that this was true.
Spalding and her postdoc advisor Jonas Frisén had a hunch that a pulse of radioactive carbon created by above-ground nuclear tests during the Cold War could help solve the riddle. “A geopolitical phenomenon—this Cold War bomb testing—has, in a way, put a date stamp on everything and everybody,” Spalding says. The bomb pulse has been declining since the 1963 above-ground test ban treaty, creating a sort of clock they could exploit. By determining how many radioactive carbon atoms a cell contained, Spalding and Frisén hoped they could calculate its birthdate. To test theory, they needed neurons—a lot of them.
Aboveground nuclear bomb tests, like this French test over Fangataufa Atoll, created a pulse of radioactive carbon in the atmosphere.
Spalding’s curiosity eventually leading her to a slaughterhouse on the outskirts of Stockholm. Standing outside the low, gray industrial building, she watched as horses went in one side and, about 15 minutes later, a worker appeared on the other end, holding a head, neurons and all. “It was precisely as revolting as it sounds,” she says. Spalding would then spend hours chipping away to extract the necessary cells, a grisly procedure that was just the first in a decade-long stretch of hurdles she had to surmount. “Had we known how difficult it was going to be, we never would have stuck with it,” says physicist Bruce Buchholz, one of Spalding’s co-authors and an expert on bomb pulse dating at the Lawrence Livermore National Laboratory outside San Francisco.But Spalding persevered, and her hard work eventually paid off. Last June, she published a paper in which she conclusively stated that adult human did indeed build new neurons in their brains. The human hippocampus, Spalding and Frisén discovered, was continually creating small numbers of neurons. They and their co-authors had solved one of neuroscience’s longstanding mysteries.
In the years leading up to that, Spalding and Frisén pioneered a new field of research, using the Cold War bomb pulse to answer a number of questions about human physiology, including neuron formation and lipid cycling. “It’s an amazingly powerful tool, whether you want to look at a fat cell or a brain cell,” Spalding says. Their work has been so fruitful that it could provide them with a lifetime worth of projects. But she and her collaborators can’t waste any time. By 2050, Frisén and Spalding estimate, the bomb pulse will have completely dissipated.
Bombs Away
The premise of bomb pulse dating is fairly straightforward. Most aboveground nuclear bomb testing happened between 1955 and 1963, and those detonations released untold numbers of neutrons into the atmosphere. These slammed into nitrogen atoms, causing their nuclei to eject a proton. What was once a seven-proton nitrogen became a six-proton carbon. But unlike most carbon atoms, which have six protons six and neutrons, this radioactive carbon, known as 14C, retained nitrogen’s two extra neutrons, a difference in atomic mass that is small, but measurable. Normally, only a tiny fraction of the world’s carbon is 14C, so little that scientists measure it in parts per trillion. The bomb pulse doubled this amount. While 14C concentrations are still low even after the bomb pulse, the difference is obvious to scientists who know what they’re looking for.To measure the small amounts of 14C, scientists use a technique called mass spectrometry, which sorts atoms by weight. When looking for carbon isotopes, the instrument strips carbon atoms of some of their electrons and launches them into a magnetic field, which alters each atom’s trajectory. Inertia causes heavier atoms, like 14C, to take a wider path than lighter ones. By measuring how many carbon atoms travel along the various paths, scientists can determine how much 14C is in a sample.
Atmospheric 14C spiked in 1955 and rapidly dropped off after the Limited Test Ban Treaty was signed in 1963, which banned all aboveground detonations. Without nuclear explosions producing new 14C, existing 14C began to mix with other carbon sinks, diluting its concentration in the air.
Radioactive 14C is incorporated into all living things: by plants that use carbon dioxide for photosynthesis, by the animals that eat the plants, by the animals that eat other animals that have eaten plants. To our bodies, one type of carbon is as good as any other, so 14C is used when building our cells, our proteins, and our DNA.
A cell’s DNA reflects the amount of 14C in the atmosphere at the time it was made. (For plants, that’s shortly after they fixed CO2 containing 14C; for animals, it’s when they ate a plant or animal containing 14C.) Scientists measure the amount of 14C in DNA because, while other molecules are frequently refreshed throughout a cell’s life, DNA remains constant. By determining the age of the DNA, researchers can determine when, exactly, a cell was created.
The Great Debate
Neuroscience dogma had long dictated that the adult human brain did not create any new neurons. The only time neuron numbers could increase was thought to be during fetal development and early childhood. Once the peak number was reached—usually around age four—it was all downhill. But by the late 1960s and early 1970s, rodent studies led some experts like Fred Gage, a neuroscientist at the Salk Institute in La Jolla, California, to question this notion.“We found stem cells in the hippocampus of adult mice and rats that could create new neurons,” Gage says. It was groundbreaking work, but at the time not everyone was convinced of its importance. “In order for this to have significance, we needed to know whether this occurred in humans.”
To identify dividing cells in mice and rats, Gage had been using a molecule known as bromodeoxyuridine, or BrdU. BrdU is a synthetic nucleoside that can be incorporated into newly synthesized DNA in place of the standard nucleoside thymidine, the T in ATCG. Instead of thymidine’s standard methyl group, BrdU has a bromine atom, a small molecular difference which researchers can detect. If a cell divides shortly after BrdU is injected into the body, the DNA of the new cells will contain BrdU.
DNA in new cells in a rat hippocampus is labeled here in green.
At that time, in the mid-1990s, BrdU was mainly used in humans as a cancer diagnostic agent to determine which parts of a tumor were rapidly dividing. Gage saw this as an opportunity to test his hypothesis, so he obtained the brains of recently deceased cancer patients who had been treated with BrdU, checking if there were neurons in the hippocampus that contained the chemical. There were. “This was the first evidence that there were dividing stem cells in an adult brain, and that these cells could give rise to new neurons in the hippocampus,” Gage says. He published his data in a 1997 paper in Nature Neuroscience.Although Gage felt he had settled the debate, not all scientists agreed. Some disputed his results because they came from cancer patients, whose bodies contained cells that weren’t behaving normally. “The reception was pretty rocky in the early days,” Gage says. “It was hard to accept that this could happen in mice and rats, not to mention people.”
Across the Atlantic, in his Stockholm lab, Frisén read Gage’s paper with interest. He, too, had believed that humans could grow new neurons, but never had the evidence to back up his hunch. BrdU was potentially toxic and carcinogenic—no research safety committee was going to allow its use on healthy subjects.
A rat hippocampus as seen through an ultra-widefield high-speed multiphoton laser microscope
Frisén initially turned to radiocarbon dating, which archaeologists use to determine the age of ancient artifacts. At best, however, the technique could only date something to within one hundred years—not nearly sensitive enough for what he needed. In his literature search, however, he stumbled across a variation on the technique that also used 14C. No one had used it to answer major questions in biology, though. “It was a high-risk project,” Frisén says. “I talked to all of the postdocs in my lab, and Kirsty was the only person willing to take on this research.”Hopes and Isotopes
One of the first significant biological applications of bomb pulse dating came in forensic science back in the early 1990s. Detectives in Vienna had found two wealthy, elderly sisters dead in an apartment in 1992, and they called on University of Vienna physicist Walter Kutschera to help to solve the mystery. To disperse the women’s substantial estates and life insurance payouts, police needed to know which had died first or if they died at the same time. The detectives had heard about bomb pulse dating, and Kutchera was a resident expert. Could he help, the police asked? Kutschera agreed. “We focused on the cells that renewed quickly, like skin and hair. If you measure something that is renewed very regularly, you can determine when that person died,” he says.Working with forensic experts, Kutschera found that the newest cells in one of the sisters dated from 1988. Sister B, however, had cells that were born in 1989. The detectives ultimately concluded that Sister A had died at home while Sister B continued to live in the same apartment as her sister’s dead body. One or two years later, Sister B also died. Since Sister B was the last alive, the detectives could disperse the sisters’ estates according to Sister B’s wishes.
Other forensic teams soon began taking advantage of bomb pulse dating. Detectives could determine date of birth and death for John and Jane Does, helping them put a name to a body. It would occasionally solve the case; other times it would give distraught relatives an answer to what had happened to their missing loved one.
The forensics technique was also used to identify victims the deadly Indian Ocean tsunami in 2004. A large number of Swedish tourists had been in the tsunami’s path, and although officials knew who had gone missing, they were having trouble matching names with the bodies. The Swedish government asked Frisén and Spalding if they could use their expertise in bomb pulse dating to make the identifications. The experience emphasized for Frisén and Spalding how useful the technique could be. “This work actually spurred us on to keep going with some of our biological research,” Frisén says.
Fat Chances
Spalding’s work on the tsunami victims bolstered her confidence that 14C dating could, in fact, accurately date not just individuals, but specific populations of cells in the body. Fortunately, she had already teamed up with Buchholz, the bomb pulse expert at Lawrence Livermore, to fine tune her technique. She then cast her net wide, dating intestinal, skeletal, brain, and blood cells, publishing the first results in July 2005 in Cell. Some cells, such as those in the cerebellum, were just three years younger than the person itself. Blood cells, on the other hand, were very young, confirming existing data about their rapid turnover. In the middle were intestinal cells, which Spalding found had an average lifespan of about 11 years.These results were crucial, Buchholz notes, because it showed the method would work in humans. “Before this study, it seemed bomb pulse dating was more of a curiosity question. People would mostly just say ‘Oh, yeah. We see it in people.’ It wasn’t used as a tool to do biology until Kirsty and Jonas just took this idea and ran with it,” Buchholz says.
To Spalding, those first experiments were satisfying, but merely a step toward her goal. Once she proved the tool worked, she set out to use it. Her first target was fat. “It has very important endocrine functions,” says biologist Philipp Scherer from the University of Texas Southwestern Medical Center in Dallas. “Adipose tissue communicates with other organs using the hormones it creates. As you go from lean to obese, the fingerprint of these hormones changes. The bad ones go up and the good ones go down, so it’s important to understand the basic physiology of these cells.”
Spalding wanted to know whether fat cells were replaced more or less quickly in obese individuals compared with their leaner counterparts. This, she felt, might help explain not only why it’s so hard for many people to lose weight and keep it off, but also some of the health complications that occur in people with excess body fat. Spalding found that the age of cells in both obese and lean people were the same: around 10 years. Her calculations showed that, each year, around 8% of an adult’s fat cells die and are replaced by new cells, a rate that didn’t vary according to body mass index. But the story was different in children: obese kids added new fat cells much more quickly than their old cells died.
Spalding also dated the fats inside adipose cells. She found that throughout a fat cell’s lifetime, lipids were replaced six times, on average. The individuals with the oldest lipids—and thus the slowest turnover rate—were more likely to be insulin resistant. The finding could pave the way for treatments that target the rate of lipid turnover to improve the health of obese individuals, even if it didn’t result in weight loss. “This technique is elegant and useful,” Scherer says. “Targeting fat cell turnover is where the field will have to go in order to get ahold of the obesity and Type 2 diabetes death spiral.”
Results at Last
After years of trial and error, tweaks, and fine tuning, Spalding was finally ready to test her and Frisén’s theory that human brains generated new neurons. The barriers, though, were still significant. Spalding first had to separate hippocampal neurons from the non-neuronal support cells that surrounded them. This took more than a year. She also had to isolate enough of their DNA—typically, she found only one 14C atom for every twelve to fourteen cells. Most detection methods required a full milligram, but Spalding realized she could only isolate a few micrograms of material. She spent a year and a half optimizing her DNA extraction technique, yet it still wasn’t enough.Frustrated, Spalding turned to another brain region that had been hotly debated in neurogenesis circles—the olfactory bulb. For many mammals, smell is the dominant sense, and scientists had discovered newly formed cells in this region in mature animals. In humans, the olfactory bulb is bigger than the hippocampus, and it contains more cells and more DNA. Unfortunately, her results didn’t mirror findings in animals. Humans, she published in Neuron, did not create new cells in the olfactory bulb.
That wasn’t the end, though. Not long after Spalding published the Neuron study, she received word that a group of scientists at Uppsala University in Sweden had developed a new technique, a more sensitive one that could measure her tiny hippocampal samples. Here was new hope, though Spalding was still skeptical. “With each step, I thought I had it, I thought ‘This is great! I’m finally there,’ ” she says, “and then there would be another problem.”
This time, however, was the exception. The determined scientist had finally cleared her last hurdle. The results were conclusive.
Using 55 brains of individuals between the ages of 19 and 92, Spalding separated the hippocampal neurons and isolated their DNA. Buchholz then took the DNA and assayed their 14C ratio. Their results showed that the average hippocampal neuron was only 20-30 years old, even in people who were more than 90 years old. Each day, the researchers estimated, the human brain creates 700 new hippocampal neurons. To the research community, the results were clear: neurogenesis occurs in humans, even long into adulthood. “We found a lot more hippocampal neurogenesis than anyone really expected,” Frisén says.
After years of work and apparent dead ends, Spalding and Frisén finally had their answer. For some, that would be the end of it. But with the bomb pulse expected to dissipate by 2050, their real work is only just beginning.
In the meantime, though, they can revel in overturning one of neuroscience’s long-held tenets. “It presents a whole new picture on our view of the brain,” Gage says of Spalding and Frisén’s research. “It’s not this static structure that just declines with age. Now we see the brain very differently.”
Subscribe to:
Posts (Atom)
Representation of a Lie group
From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Representation_of_a_Lie_group...
-
From Wikipedia, the free encyclopedia Islamic State of Iraq and the Levant الدولة الإسلامية في العراق والشام ( ...
-
From Wikipedia, the free encyclopedia A reproduction of the palm -leaf manuscript in Siddham script ...
David Strumfels comments (so far):