Minority rules: Scientists discover tipping point for the spread of ideas

ScienceDaily (July 25, 2011) — Scientists at Rensselaer Polytechnic Institute have found that when just 10 percent of the population holds an unshakable belief, their belief will always be adopted by the majority of the society. The scientists, who are members of the Social Cognitive Networks Academic Research Center (SCNARC) at Rensselaer, used computational and analytical methods to discover the tipping point where a minority belief becomes the majority opinion. The finding has implications for the study and influence of societal interactions ranging from the spread of innovations to the movement of political ideals.See Also:Mind & BrainSocial PsychologyRelationshipsComputers & MathComputer ModelingMathematical ModelingScience & SocietyEthicsPolitical ScienceLiving WellStrange ScienceReferenceCognitive biasFunctional neuroimagingIntuition (knowledge)Culture of fear

"When the number of committed opinion holders is below 10 percent, there is no visible progress in the spread of ideas. It would literally take the amount of time comparable to the age of the universe for this size group to reach the majority," said SCNARC Director Boleslaw Szymanski, the Claire and Roland Schmitt Distinguished Professor at Rensselaer. "Once that number grows above 10 percent, the idea spreads like flame."

As an example, the ongoing events in Tunisia and Egypt appear to exhibit a similar process, according to Szymanski. "In those countries, dictators who were in power for decades were suddenly overthrown in just a few weeks."

The findings were published in the July 22, 2011, early online edition of the journal Physical Review E in an article titled "Social consensus through the influence of committed minorities."

An important aspect of the finding is that the percent of committed opinion holders required to shift majority opinion does not change significantly regardless of the type of network in which the opinion holders are working. In other words, the percentage of committed opinion holders required to influence a society remains at approximately 10 percent, regardless of how or where that opinion starts and spreads in the society.

To reach their conclusion, the scientists developed computer models of various types of social networks. One of the networks had each person connect to every other person in the network. The second model included certain individuals who were connected to a large number of people, making them opinion hubs or leaders. The final model gave every person in the model roughly the same number of connections. The initial state of each of the models was a sea of traditional-view holders. Each of these individuals held a view, but were also, importantly, open minded to other views.

Once the networks were built, the scientists then "sprinkled" in some true believers throughout each of the networks. These people were completely set in their views and unflappable in modifying those beliefs. As those true believers began to converse with those who held the traditional belief system, the tides gradually and then very abruptly began to shift.

"In general, people do not like to have an unpopular opinion and are always seeking to try locally to come to consensus. We set up this dynamic in each of our models," said SCNARC Research Associate and corresponding paper author Sameet Sreenivasan. To accomplish this, each of the individuals in the models "talked" to each other about their opinion. If the listener held the same opinions as the speaker, it reinforced the listener's belief. If the opinion was different, the listener considered it and moved on to talk to another person. If that person also held this new belief, the listener then adopted that belief.

"As agents of change start to convince more and more people, the situation begins to change," Sreenivasan said. "People begin to question their own views at first and then completely adopt the new view to spread it even further. If the true believers just influenced their neighbors, that wouldn't change anything within the larger system, as we saw with percentages less than 10."

The research has broad implications for understanding how opinion spreads. "There are clearly situations in which it helps to know how to efficiently spread some opinion or how to suppress a developing opinion," said Associate Professor of Physics and co-author of the paper Gyorgy Korniss. "Some examples might be the need to quickly convince a town to move before a hurricane or spread new information on the prevention of disease in a rural village."

The researchers are now looking for partners within the social sciences and other fields to compare their computational models to historical examples. They are also looking to study how the percentage might change when input into a model where the society is polarized. Instead of simply holding one traditional view, the society would instead hold two opposing viewpoints. An example of this polarization would be Democrat versus Republican.

The research was funded by the Army Research Laboratory (ARL) through SCNARC, part of the Network Science Collaborative Technology Alliance (NS-CTA), the Army Research Office (ARO), and the Office of Naval Research (ONR).

The research is part of a much larger body of work taking place under SCNARC at Rensselaer. The center joins researchers from a broad spectrum of fields -- including sociology, physics, computer science, and engineering -- in exploring social cognitive networks. The center studies the fundamentals of network structures and how those structures are altered by technology. The goal of the center is to develop a deeper understanding of networks and a firm scientific basis for the newly arising field of network science. More information on the launch of SCNARC can be found at http://news.rpi.edu/update.do?artcenterkey

Scientists discover potential stroke treatment that may extend time to prevent brain damage

ScienceDaily (July 25, 2011) — A naturally occurring substance shrank the size of stroke-induced lesions in the brains of experimental mice -- even when administered as much as 12 hours after the event, Stanford University School of Medicine researchers have shown. The substance, alpha-B-crystallin, acts as a brake on the immune system, lowering levels of inflammatory molecules whose actions are responsible for substantial brain damage above and beyond that caused by the initial oxygen deprivation of a stroke.See Also:Health & MedicineStroke PreventionHeart DiseaseElder CareMind & BrainBrain InjuryStrokeCaregivingReferenceMulti-infarct dementiaBrain damageStrokeNeurology

The finding, which will be published online July 25 in Proceedings of the National Academy of Sciences, is of great potential significance. Every year brings nearly 800,000 new stroke patients in North America. "That's one every 40 seconds," said Gary Steinberg, MD, PhD, director of Stanford's Institute for Neuro-Innovation and Translational Neurosciences and one of the study's two senior authors. Steinberg is also the Bernard and Ronni Lacroute-William Randolph Hearst Professor of Neurosurgery and the Neurosciences, and chair of neurosurgery at the medical school.

The largest single cause of severe neurological disability and the third-leading cause of death in the United States, stroke accounts for an estimated $74 billion annually in related costs, including treatment and additional assistance for the three of every four stroke patients whose ability to perform the activities of daily life is impaired. Strokes are caused by a sudden drop in the flow of blood to the brain resulting from a clot or, less often, bleeding. One of every three stroke patients is under the age of 65. In all, there are 5.4 million stroke survivors in the United States and 15 million worldwide.

The only currently approved drug for stroke -- tissue plasminogen activator, or tPA -- dissolves clots that keep oxygenated blood from reaching brain tissue. To be effective, tPA must be administered within about 4.5 hours after the stroke. But patients' brains must first be scanned to rule out the possibility that the stroke was caused by bleeding, which tPA would exacerbate, rather than by blockage.

Moreover, tPA does nothing to counter the stroke's insidious inflammatory aftershock: a flood of noxious chemicals secreted by angry immune cells that rush in to the affected area, causing significant further damage.

Alpha-B-crystallin appears to act as a sponge, sopping up those bad actors and stopping inflammation from making a bad situation worse.

Alpha-B-crystallin is a major structural protein in the eye's lens. It is also constantly made in the heart. In other tissues, including the brain, its production can be triggered by stressful events, such as oxygen deprivation or excessive heat or cold. Growing evidence suggests that alpha-B-crystallin can help curb inflammatory activity in the brain.

"The brain doesn't roll over and play dead when it's under attack," said Lawrence Steinman, MD, the other senior author of the new study, who is the George A. Zimmermann Professor of Neurology and Neurological Sciences and Pediatrics as well as chair of Stanford's interdepartmental program in immunology.

In an earlier study, published in Nature in 2007, Steinman and his colleagues found that the presence of alpha-B-crystallin could help reduce the severity of brain damage caused by multiple sclerosis, a chronic, debilitating autoimmune disease of the brain. Other studies published this year by his group have shown that alpha-B-crystallin limits the damage caused by blood-supply cutoffs to heart tissue and the retina.

It seemed logical to see if this protein could mitigate the effects of a stroke. "We made a jump from its relevance in inflammatory diseases such as multiple sclerosis," Steinberg said. "To my knowledge, nobody had looked at concentrations of alpha-B-crystallin after a stroke, either in people or in an experimental animal model before."

So, along with first authors Ahmet Arac, MD, a postdoctoral scholar in Steinberg's lab, and Steinman's former graduate student Sarah Brownell, PhD, Steinberg and Steinman turned to a standard animal model: the laboratory mouse. They found that, in mice bioengineered to lack alpha-B-crystallin, experimentally induced stroke lesions were more massive than those induced in otherwise genetically similar mice whose cells were capable of making the protein. The alpha-B-crystallin-deficient mice had worse neurological function after the stroke than did the normal mice.

The researchers also found that supplying synthetic alpha-B-crystallin to the deficient mice reduced brain-lesion sizes after a stroke, even when the substance was administered 12 hours after the stroke was induced. And they saw elevated alpha-B-crystallin levels in blood plasma from both human patients and mice after a stroke. (The human samples were obtained from study co-author Gregory Albers, MD, the Coy Foundation Professor of Neurology and Neurological Sciences and the director of the Stanford Stroke Center).

"In younger patients, the larger the stroke, the higher the concentration of alpha-B-crystallin," said Steinberg. Interestingly, increased alpha-B-crystallin levels were not detected in plasma from patients over the age of 80, whose strokes typically have worse consequences than those affecting younger patients.

Finally, the investigators demonstrated that alpha-B-crystallin-treated mice produce fewer inflammatory immune-signaling molecules and more anti-inflammatory ones than untreated mice.

At the doses given to the mice in this study, alpha-B-crystallin appeared to be nontoxic. "This is a naturally occurring molecule the body is already producing, although maybe just not enough of it," said Steinberg. "We're just supplementing it." If further studies by other labs and in other models confirm and extend the findings, alpha-B-crystallin may be an excellent candidate for clinical trials in stroke, Steinman and Steinberg both said.

"This is the first demonstration of an efficacious brain-protecting agent that targets the inflammatory aspect of stroke in a novel way, and it can be given at quite a delay," said Thomas Carmichael, MD, PhD, professor and vice chair of neurology at the David Geffen School of Medicine at UCLA. Carmichael, a stroke expert, did not participate in the study but is familiar with its methodology and results. "Tissue plasminogen activator has a fairly narrow risk-to-benefit ratio. The longer you wait, the more likely it is to stimulate a hemorrhage."

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Astronomers discover largest and most distant reservoir of water yet

ScienceDaily (July 22, 2011) — Water really is everywhere. Two teams of astronomers, each led by scientists at the California Institute of Technology (Caltech), have discovered the largest and farthest reservoir of water ever detected in the universe. Looking from a distance of 30 billion trillion miles away into a quasar -- one of the brightest and most violent objects in the cosmos -- the researchers have found a mass of water vapor that's at least 140 trillion times that of all the water in the world's oceans combined, and 100,000 times more massive than the sun.See Also:Space & TimeAstrophysicsBlack HolesCosmologyAstronomyGalaxiesStarsReferenceQuasarSupergiantSpitzer space telescopeHubble Deep Field

Because the quasar is so far away, its light has taken 12 billion years to reach Earth. The observations therefore reveal a time when the universe was just 1.6 billion years old. "The environment around this quasar is unique in that it's producing this huge mass of water," says Matt Bradford, a scientist at NASA's Jet Propulsion Laboratory (JPL), and a visiting associate at Caltech. "It's another demonstration that water is pervasive throughout the universe, even at the very earliest times." Bradford leads one of two international teams of astronomers that have described their quasar findings in separate papers that have been accepted for publication in the Astrophysical Journal Letters.

A quasar is powered by an enormous black hole that is steadily consuming a surrounding disk of gas and dust; as it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279