Science, magic and monsters meet at book fest

The giant green dinosaur will once again rise above Decatur Square for Labor Day weekend, with the return of the Decatur Book Festival and its inflatable monster mascot, Bookzilla.

One of the most popular aspects of the festival is the Science Track organized by Atlanta Science Tavern. Emory psychologist Scott Lilienfeld has been tapped to give a short intro for a talk by Alex Stone, a physicist and a magician who will speak at 5 pm on Sunday about his new book “Fooling Houdini: Magicians, Mentalists, Math Geeks and the Hidden Powers of the Mind.”

Stone notes in his book, “the world of magic is filled with scientists and the world of science is filled with magicians.”

Lilienfeld is just one example of this phenomenon. “I’ve always loved magic tricks,” he says. “I like being fooled by them, and I like trying to figure out how I got duped.”

Magicians have contributed a lot to the science of psychology, Lilienfeld says, by demonstrating the powers of “change blindness” the “illusion of choice” and other mysterious cognitive patterns.

“One of my keen interests is the psychology of deception,” Lilienfeld says. “To me, that’s what science is all about, to minimize the possibility of deception.”


A trailer for the sci-fi book "Year Zero," one of the titles at the book fest.

The potential of thorium as a super fuel, theories of consciousness, lithium batteries, electric cars and astounding tales hidden in the human genetic code are some of the other science subjects that will be highlighted at the festival. Click here to see the complete listing of Science Track authors.

The festival also has an Environmental Issues Track including novelist Lauren Groff and Georgia ecologist Janisse Ray. A Health and Wellness Track includes a panel discussion on "Tackling Obesity Issues," moderated by Emory psychologist Linda Craighead.

Science-fiction fans will have a chance to hear Lydia Netzer talk about her metaphysical novel "Shine, Shine, Shine," and Rob Reid on "Year Zero," his novel about music pirates from outer space. (Check out the trailer for "Year Zero" in the video, above.)

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Analysis finds benefits to racial quotas in Brazilian higher education

“For a long time, Brazil was known as a racial democracy with little discrimination, but social science research in recent decades has shown that view was way off," says economist Andy Francis.

By Carol Clark

A racial quota system at one of the leading universities in Brazil raised the proportion of black students from low-income families, without decreasing their efforts to succeed in school, a major new study finds.

“Critics of affirmative action policies often argue that making it easier for people to get into college lowers their incentive to try hard academically. That argument doesn’t stand up to our data,” says Andrew Francis, an economist at Emory University and co-author of the study.

Francis conducted the research with Maria Tannuri-Pianto, an economist at the University of Brasilia. Their analysis of the short-term impact of racial quotas was recently published in the Journal of Human Resources.

Affirmative action has been in place for decades in the United States, but it remains controversial, especially in regards to higher education. Some states have even taken steps to weaken the policy, which does not include racial quotas.

On October 10, the debate will come back to the forefront, as the U.S. Supreme Court hears arguments in Fisher v. University of Texas at Austin. A rejected white student brought the challenge to the admission policies of UT, a flagship public university.

Boys playing soccer in a slum in Rio de Janeiro, a city of extreme poverty and wealth and the host of the 2016 Olympics.

Brazil offers a diverse and vibrant environment to study how incentives affect education and race. The country’s status as a rising star on the world stage was boosted by its winning bid to host the 2016 Olympics.

More African slaves were brought to Brazil than to all of North America. Many of their descendants have intermarried with other races in Brazil, including indigenous people and those of European and Asian descent.

“For a long time, Brazil was known as a racial democracy with little discrimination, but social science research in recent decades has shown that view was way off,” Francis says. “Generally, the darker your skin in Brazil, the less education and money you have. Brazil is a country of stark contrasts.”

Brazil is just beginning to experiment with its own brand of affirmative action. In 2004, the University of Brasilia became the first federal university to have a racial quota system. All students must pass an admissions exam in order to gain entrance to the university. The racial quota requires each department at the university to reserve 20 percent of its admission spaces for students who self-identify as black.

In order to conduct a comparative analysis, the researchers looked at two admission cycles before the quota system was enacted, and three admission cycles following implementation. The university cooperated with the researchers, giving them access to admissions scores, grades and other pertinent information.

"Brazil is a country of stark contrasts."

More than 2,000 students were interviewed over the course of the study. They were asked to self-identify as belonging to one of five racial groups, from white to black and gradations between. Photographs were taken of more than 700 students. The photos were shown to a panel of Brazilians who were asked to rate the skin tones on a scale of one to seven, from lightest to darkest.

The results showed that the racial policies boosted the numbers of the darkest-skinned students overall, from 5.6 percent to 9 percent. The successful applicants were from lower socioeconomic status families than the displaced applicants.

To analyze how the racial quota impacted student effort, the researchers looked at whether the students took a college preparation course, how many times they applied, and whether they applied to more competitive academic departments, like law and medicine.

“Based on our analysis of those factors, there was no evidence that students reduced their efforts due to racial quotas,” Francis says.

The researchers also did a comparative analysis of grades. “The policy did not impact the grades of black students,” Francis says. “There were some racial disparities before and after, with black students on average getting lower grades than white students, but the policies didn’t exacerbate this difference.”

Another aspect of the study was how the racial quotas affected racial self-identity. “We found some evidence that people misrepresented their racial identity after the quota system was enacted,” Francis says. “Some of the students told the university that they were black, but during interviews for our study, they told us that they were not black. People of intermediate skin tone were more likely to make this switch.”

People of the darkest skin tone, however, were more likely after the racial quota policy was implemented to identify themselves as black, both on their university application and for the study survey. “The racial quota policy caused them to see themselves in a different way,” Francis says. “It seemed to reinforce and foster investments in a black identity. Race is flexible and contextual, and our data shows that public policy can have an impact on racial self-identification.”

In a recent case, the Brazilian Supreme Court unanimously upheld the constitutionality of the racial quota system, giving the federal government a green light for implementing more racial quotas as it seeks to correct economic imbalances.

“We hope our data helps shape Brazil’s racial policy,” Francis says, adding that additional policy interventions need to be pursued. “College entrance exam scores are lower for blacks in Brazil for many reasons,” he says. “If society is really committed to erasing inequality, policies have to impact people earlier in life than college.”

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All photos by iStockphoto.com.

Capuchin economics: Monkeys on unequal pay

Outrage in the face of inequity goes way back in our evolutionary history, suggests research by Emory primatologist Frans de Waal.

In a classic experiment, de Waal demonstrated that capuchin monkeys reject unequal rewards. In a video clip from a recent de Waal talk for TED (see above), you can see what happens when one monkey receives a cucumber for a task, while another monkey receives a grape for the same task.

“It’s basically the Wall Street protests,” de Waal says.

De Waal will be one of the featured speakers at a major Emory conference devoted to the topic of fairness, set for October 18-19. “What is Fair? An Interdisciplinary Relection on the Meanings of Fairness” will bring together psychologists, ethicists, lawyers, anthropologists, economists and former President Jimmy Carter to explore the many layers of a complex subject.

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Biophysicists unravel secrets of genetic switch

"I hope this kind of experiment will lead to better understanding of how our own DNA is compacted into chromosomes, and how it unravels locally to become expressed," says biophysicist Laura Finzi.

By Carol Clark

When an invading bacterium or virus starts rummaging through the contents of a cell nucleus, using proteins like tiny hands to rearrange the host’s DNA strands, it can alter the host’s biological course. The invading proteins use specific binding, firmly grabbing onto particular sequences of DNA, to bend, kink and twist the DNA strands. The invaders also use non-specific binding to grasp any part of a DNA strand, but these seemingly random bonds are weak.

Emory University biophysicists have experimentally demonstrated, for the fist time, how the nonspecific binding of a protein known as the lambda repressor, or C1 protein, bends DNA and helps it close a loop that switches off virulence. The researchers also captured the first measurements of that compaction.

Their results, published in Physical Review E, support the idea that nonspecific binding is not so random after all, and plays a critical role in whether a pathogen remains dormant or turns virulent.

“Our findings are the first direct and quantitative determination of non-specific binding and compaction of DNA,” says Laura Finzi, an Emory professor of biophysics whose lab led the study. “The data are relevant for the understanding of DNA physiology, and the dynamic characteristics of an on-off switch for the expression of genes.”

Lysis plaques of lambda phage on E. coli bacteria.

C1 is the repressor protein of the lambda bacteriophage, a virus that infects the bacterial species E. coli, and a common laboratory model for the study of gene transcription.

The virus infects E. coli by injecting its DNA into the host cell. The viral DNA is then incorporated in the bacterium’s chromosome. Shortly afterwards, binding of the C1 protein to specific sequences on the viral DNA induces the formation of a loop. As long as the loop is closed, the virus remains dormant. If the loop opens, however, the machinery of the bacteria gets hi-jacked: The virus switches off the bacteria’s genes and switches on its own, turning virulent.

“The loop basically acts as a molecular switch, and is very stable during quiescence, yet it is highly sensitive to the external environment,” Finzi says. “If the bacteria is starved or poisoned, for instance, the viral DNA receives a signal that it’s time to get off the boat and spread to a new host, and the loop is opened. We wanted to understand how this C1-mediated, loop-based mechanism can be so stable during quiescence, and yet so responsive to switching to virulence when it receives the signal to do so.”

Transient-loop formation, left, occurs due to non-specific binding of proteins (small orange disks) to DNA (black line). DNA is attached at one end to the glass surface of a microscope flow-chamber and at the other end to a magnetic bead (large gray disk) that reacts to the pulling force of a pair of magnets. The weak, non-specific DNA-protein interactions are disrupted as the force increases. (Graphic by Monica Fernandez.)

Finzi runs one of a handful of physics labs using single-molecule techniques to study the mechanics of gene expression. In 2009, her lab proved the formation of the C1 loop. “We then analyzed the kinetics of loop formation and gained evidence that non-specific binding played a role,” Finzi says. “We wanted to build on that work by precisely characterizing that role.”

Emory undergraduate student Chandler Fountain led the experimental part of the study. He used magnetic tweezers, which can pull on DNA molecules labeled with miniscule magnetic beads, to stretch DNA in a microscope flow chamber. Gradually, the magnets are moved closer to the DNA, pulling it further, so the length of the DNA extension can be plotted against the applied force.

“You get a curve,” Finzi explains. “It’s not linear, because DNA is a spring. Then you put the same DNA in the presence of C1 protein and see how the curve changes. Now, you need more force to get to the same extension because the protein holds onto the DNA and bends it.”

Specifically-bound proteins are shown as orange ovals on a thicker part of the DNA sequence and non-specifically bound proteins are portrayed as gray ovals on regular DNA. Non-specific, transient loops facilitate the coming together of the specifically-bound proteins that mediate formation of the “switch loop”. Once this loop is formed, non-specifically bound protein further stabilize it by increasing the length of the closure in a zipper-like effect. (Graphic by Monica Fernandez.)

An analysis of the data suggests that, while the specific binding of the C1 protein forms the loop, the non-specific binding acts like a kind of zipper, facilitating the closure of the loop, and keeping it stable until the signal comes to open it.

“The zipper-like effect of the weaker binding sites also allows the genetic switch to be more responsive to the environment, providing small openings that allow it to breathe, in a sense,” Finzi explains. “So the loop is never permanently closed.”

The information about how the C1 genetic switch works may provide insights into the workings of other genetic switches.

“Single-molecule techniques have opened a new era in the mechanics of biological processes,” Finzi says. “I hope this kind of experiment will lead to better understanding of how our own DNA is compacted into chromosomes, and how it unravels locally to become expressed.”

Other authors on the paper include Sachin Goyal, formerly a post-doc in the Finzi lab; Emory cell biologist David Dunlap; and Emory theoretical physicist Fereydoon Family. The research was funded by the National Institutes of Health.

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Image credits: DNA (top) by iStockphoto.com; lamba phage by Madboy via Wikipedia Commons.

Acai berries can lengthen lives of fruit flies

Harvesting acai berries in the Brazilian Amazon. Products made from the berries are sold around the world, and are often marketed as health supplements.

By Quinn Eastman, Woodruff Health Sciences Center

Bewildered by the array of antioxidant fruit juices on display in the supermarket and the promises they make? To sort out the antioxidant properties of fruits and berries, scientists at Emory University School of Medicine turned to fruit flies for help.

They found that a commercially available acai berry product can lengthen the lives of fruit flies, when the flies’ lives are made short through additional oxidative stress. Under certain conditions (a simple sugar diet) acai supplementation could triple flies’ lifespans, from eight to 24 days. Acai could also counteract the neurotoxic effects of the herbicide paraquat on the flies.

The results were recently published by the journal Experimental Gerontology, which awarded the paper its inaugural "Outstanding paper" prize. The lead author is Alysia Vrailas-Mortimer, a postdoctoral fellow in Emory University School of Medicine’s Department of Cell Biology. Vrailas-Mortimer says she didn’t start out focusing on acai. But acai worked better than several other antioxidant products such as vitamins, coenzyme Q10 and lutein.

"One thing that makes our work distinctive is that we tried commercially available supplements," she says. "We went to a health food store and filled up a basket."

She says she began the project with the help of undergraduate student Rosy Gomez, and narrowed her focus after initial success with acai. Vrailas-Mortimer took advantage of a discovery she had made working with Subhabrata Sanyal, assistant professor of cell biology. They had previously found that flies with mutations in the "p38 MAP kinase" gene have shorter lives and are more sensitive to heat, food deprivation and oxidative stress.

P38 mutant flies lived an average of only eight days when they were given a simple sugar water diet. However, their lifespans tripled when their diet was supplemented with acai. Ginger was used as a control for the diet supplements.

Acai also protected normal flies against oxidative stress, in the form of hydrogen peroxide or paraquat. Acai can protect against oxidative stress when flies are exposed to hydrogen peroxide before being given acai, but the protective effect does not hold up if the order is reversed.

Paraquat is an herbicide that has neurotoxic effects that resemble Parkinson’s disease. Under the influence of paraquat, flies’ sleep-wake cycles gradually become chaotic (see graph, above). Acai can also help soften the effects of paraquat on flies’ circadian rhythms.

"I think this is important," Vrailas-Mortimer says. "We show that whatever is in acai that is lengthening lifespan, it can also keep the flies functioning better for longer when faced with paraquat exposure. It is maintaining quality of life rather than just preventing them from dying."

Read more at Emory News Center.

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Photo: iStockphoto.com.