Mathematical Model Explains How Complex Societies Emerge, Collapse

The research, led Sergey Gavrilets, associate director for scientific activities at the National Institute for Mathematical and Biological Synthesis and a professor at the University of Tennessee-Knoxville, is published in the first issue of the new journalCliodynamics: The Journal of Theoretical and Mathematical History, the first academic journal dedicated to research from the emerging science of theoretical history and mathematics.

The numerical model focuses on both size and complexity of emerging"polities" or states as well as their longevity and settlement patterns as a result of warfare. A number of factors were measured, but unexpectedly, the largest effect on the results was due to just two factors -- the scaling of a state's power to the probability of winning a conflict and a leader's average time in power. According to the model, the stability of large, complex polities is strongly promoted if the outcomes of conflicts are mostly determined by the polities' wealth or power, if there exist well-defined and accepted means of succession, and if control mechanisms within polities are internally specialized. The results also showed that polities experience what the authors call"chiefly cycles" or rapid cycles of growth and collapse due to warfare.

The wealthiest of polities does not necessarily win a conflict, however. There are many other factors besides wealth that can affect the outcome of a conflict, the authors write. The model also suggests that the rapid collapse of a polity can occur even without environmental disturbances, such as drought or overpopulation.

By using a mathematical model, the researchers were able to capture the dynamical processes that cause chiefdoms, states and empires to emerge, persist and collapse at the scale of decades to centuries.

"In the last several decades, mathematical models have been traditionally important in the physical, life and economic sciences, but now they are also becoming important for explaining historical data," said Gavrilets."Our model provides theoretical support for the view that cultural, demographic and ecological conditions can predict the emergence and dynamics of complex societies."

Co-authors are David G. Anderson, professor of anthropology at the University of Tennessee-Knoxville and Peter Turchin, professor of ecology and evolutionary biology and mathematics at the University of Connecticut.

The National Institute for Mathematical and Biological Synthesis (NIMBioS) brings together researchers from around the world to collaborate across disciplinary boundaries to investigate solutions to basic and applied problems in the life sciences. NIMBioS is sponsored by the National Science Foundation, the U.S. Department of Homeland Security, and the U.S. Department of Agriculture with additional support from The University of Tennessee, Knoxville.

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Interactive Window Shopping: Just Wave Your Hands

A woman passing by the window display is captivated and asks her companion"Isn't the leather bag chic?""Which one do you mean? There are so many of them." The woman points to one of the bags and as if by magic the luxurious purse appears on a display behind the shop window. Then she points to a button and the designer object rotates on the screen."So that's what it looks like from the back." The woman passing by is impressed. She makes another gesture to zoom the bag towards her letting her to see every detail.

This particular shopping experience is courtesy of new type of 3-D camera system from the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute (HHI) in Berlin, Germany. Its interactive shop window enables people passing by to put goods behind shop windows onto a display with simple hand and facial gestures. Paul Chojecki is a scientist at the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute and he puts it this way:"Interactive shopping has been standard operating procedure in the web for a long time. Now, we're putting this technology into pedestrian passageways and shopping centers with the entire unit behind the window."

Four little cameras continually record the 3-D positions of the hands, faces and eyes of persons passing by. Then, image-processing software calculates the coordinates and transforms them into the corresponding inputs for selecting goods, viewing them in detail and immediately purchasing them -- even after business hours. Anyone interested can have also themselves shown product information such as color, material, price, availability and information on the manufacturer. Paul Chojecki remarks that"there's nothing comparable in Germany yet and today shops only use touchscreens in shop windows, if at all. But, you can interact with our interactive shop window without any physical contact, which is a benefit if hygiene is important to you."

The interactive shop window consists of four cameras and visualization software. Two of these stereo cameras record the face and eyes while the other two record the motion of the hands. Image processing recognizes both gestures such as when you turn your hand and when you point to a button with your finger that you can see on a monitor. The researcher adds that"the system doesn't store any personal data and only the coordinates of the body parts it recognizes are passed onto the visualization."

Interactive shop window is compatible with all displays and the shop owner can select any monitor size or type of monitor from plasma, LED, LCD, projection or reprojection screens. Beyond this, shop owners can link the system with any software already there such as content management or merchandise information system enabling them to portray all of their stock of goods on the display. The way the payment process is taken care of is also left up to the shop owner. But that's not all. The interactive shop window not only identifies how many people are in front of the shop window, but it also can suggest on the basis of the gathered data what products and information the people passing by are interested in. Finally, it has customized greeting texts on the display to guarantee a close bond to the customer.

The interactive shop window was developed for use in shopping centers and the retail trade, although Chojecki thinks it would be possible to install it in museums or at trade fairs. This 3-D recording system is only a prototype at present.

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Quantum Quirk Contained

"We have demonstrated, for the first time, that a crystal can store information encoded into entangled quantum states of photons," says paper co-author Dr. Wolfgang Tittel of the University of Calgary's Institute for Quantum Information Science."This discovery constitutes an important milestone on the path toward quantum networks, and will hopefully enable building quantum networks in a few years."

In current communication networks, information is sent through pulses of light moving through optical fibre. The information can be stored on computer hard disks for future use.

Quantum networks operate differently than the networks we use daily.

"What we have is similar but it does not use pulses of light," says Tittel, who is a professor in the Department of Physics and Astronomy at the University of Calgary."In quantum communication, we also have to store and retrieve information. But in our case, the information is encoded into entangled states of photons."

In this state, photons are"entangled," and remain so even when they fly apart. In a way, they communicate with each other even when they are very far apart. The difficulty is getting them to stay put without breaking this fragile quantum link.

To achieve this task, the researchers used a crystal doped with rare-earth ions and cooled it to -270 Celsius. At these temperatures, material properties change and allowed the researchers to store and retrieve these photons without measurable degradation.

An important feature is that this memory device uses almost entirely standard fabrication technologies."The resulting robustness, and the possibility to integrate the memory with current technology such as fibre-optic cables is important when moving the currently fundamental research towards applications."

Quantum networks will allow the sending of information without one being afraid of somebody listening in.

"The results show that entanglement, a quantum physical property that has puzzled philosophers and physicists since almost hundred years, is not as fragile as is generally believed," says Tittel.

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Fruit Fly Nervous System Provides New Solution to Fundamental Computer Network Problem

With a minimum of communication and without advance knowledge of how they are connected with each other, the cells in the fly's developing nervous system manage to organize themselves so that a small number of cells serve as leaders that provide direct connections with every other nerve cell, said author Ziv Bar-Joseph, associate professor of machine learning at Carnegie Mellon University.

The result, the researchers report in the Jan. 14 edition of the journalScience, is the same sort of scheme used to manage the distributed computer networks that perform such everyday tasks as searching the Web or controlling an airplane in flight. But the method used by the fly's nervous system to organize itself is much simpler and more robust than anything humans have concocted.

"It is such a simple and intuitive solution, I can't believe we did not think of this 25 years ago," said co-author Noga Alon, a mathematician and computer scientist at Tel Aviv University and the Institute for Advanced Study in Princeton, N.J.

Bar-Joseph, Alon and their co-authors -- Yehuda Afek of Tel Aviv University and Naama Barkai, Eran Hornstein and Omer Barad of the Weizmann Institute of Science in Rehovot, Israel -- used the insights gained from fruit flies to design a new distributed computing algorithm. They found it has qualities that make it particularly well suited for networks in which the number and position of the nodes is not completely certain. These include wireless sensor networks, such as environmental monitoring, where sensors are dispersed in a lake or waterway, or systems for controlling swarms of robots.

"Computational and mathematical models have long been used by scientists to analyze biological systems," said Bar-Joseph, a member of the Lane Center for Computational Biology in Carnegie Mellon's School of Computer Science."Here we've reversed the strategy, studying a biological system to solve a long-standing computer science problem."

Today's large-scale computer systems and the nervous system of a fly both take a distributive approach to performing tasks. Though the thousands or even millions of processors in a computing system and the millions of cells in a fly's nervous system must work together to complete a task, none of the elements need to have complete knowledge of what's going on, and the systems must function despite failures by individual elements.

In the computing world, one step toward creating this distributive system is to find a small set of processors that can be used to rapidly communicate with the rest of the processors in the network -- what graph theorists call a maximal independent set (MIS). Every processor in such a network is either a leader (a member of the MIS) or is connected to a leader, but the leaders are not interconnected.

A similar arrangement occurs in the fruit fly, which uses tiny bristles to sense the outside world. Each bristle develops from a nerve cell, called a sensory organ precursor (SOP), which connects to adjoining nerve cells, but does not connect with other SOPs.

For three decades, computer scientists have puzzled over how processors in a network can best elect an MIS. The common solutions use a probabilistic method -- similar to rolling dice -- in which some processors identify themselves as leaders, based in part on how many connections they have with other processors. Processors connected to these self-selected leaders take themselves out of the running and, in subsequent rounds, additional processors self-select themselves and the processors connected to them take themselves out of the running. At each round, the chances of any processor joining the MIS (becoming a leader) increases as a function of the number of its connections.

This selection process is rapid, Bar-Joseph said, but it entails lots of complicated messages being sent back and forth across the network, and it requires that all of the processors know in advance how they are connected in the network. That can be a problem for applications such as wireless sensor networks, where sensors might be distributed randomly and all might not be within communication range of each other.

During the larval and pupal stages of a fly's development, the nervous system also uses a probabilistic method to select the cells that will become SOPs. In the fly, however, the cells have no information about how they are connected to each other. As various cells self-select themselves as SOPs, they send out chemical signals to neighboring cells that inhibit those cells from also becoming SOPs. This process continues for three hours, until all of the cells are either SOPs or are neighbors to an SOP, and the fly emerges from the pupal stage.

In the fly, Bar-Joseph noted, the probability that any cell will self-select increases not as a function of connections, as in the typical MIS algorithm for computer networks, but as a function of time. The method does not require advance knowledge of how the cells are arranged. The communication between cells is as simple as can be.

The researchers created a computer algorithm based on the fly's approach and proved that it provides a fast solution to the MIS problem."The run time was slightly greater than current approaches, but the biological approach is efficient and more robust because it doesn't require so many assumptions," Bar-Joseph said."This makes the solution applicable to many more applications."

This research was supported in part by grants from the National Institutes of Health and the National Science Foundation.

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Couch Potatoes Beware: Too Much Time Spent Watching TV Is Harmful to Heart Health

Data show that compared to people who spend less than two hours each day on screen-based entertainment like watching TV, using the computer or playing video games, those who devote more than four hours to these activities are more than twice as likely to have a major cardiac event that involves hospitalization, death or both.

The study -- the first to examine the association between screen time and non-fatal as well as fatal cardiovascular events -- also suggests metabolic factors and inflammation may partly explain the link between prolonged sitting and the risks to heart health.

"People who spend excessive amounts of time in front of a screen -- primarily watching TV -- are more likely to die of any cause and suffer heart-related problems," said Emmanuel Stamatakis, PhD, MSc, Department of Epidemiology and Public Health, University College London, United Kingdom."Our analysis suggests that two or more hours of screen time each day may place someone at greater risk for a cardiac event."

In fact, compared with those spending less than two hours a day on screen-based entertainment, there was a 48% increased risk of all-cause mortality in those spending four or more hours a day and an approximately 125% increase in risk of cardiovascular events in those spending two or more hours a day. These associations were independent of traditional risk factors such as smoking, hypertension, BMI, social class, as well as exercise.

The findings have prompted authors to advocate for public health guidelines that expressly address recreational sitting (defined as during non-work hours), especially as a majority of working age adults spend long periods being inactive while commuting or being slouched over a desk or computer.

"It is all a matter of habit. Many of us have learned to go back home, turn the TV set on and sit down for several hours -- it's convenient and easy to do. But doing so is bad for the heart and our health in general," said Dr. Stamatakis."And according to what we know so far, these health risks may not be mitigated by exercise, a finding that underscores the urgent need for public health recommendations to include guidelines for limiting recreational sitting and other sedentary behaviors, in addition to improving physical activity."

Biological mediators also appear to play a role. Data indicate that one fourth of the association between screen time and cardiovascular events was explained collectively by C-reactive protein (CRP), body mass index, and high-density lipoprotein cholesterol suggesting that inflammation and deregulation of lipids may be one pathway through which prolonged sitting increases the risk for cardiovascular events. CRP, a well-established marker of low-grade inflammation, was approximately two times higher in people spending more than four hours of screen time per day compared to those spending less than two hours a day.

Dr. Stamatakis says the next step will be to try to uncover what prolonged sitting does to the human body in the short- and long-term, whether and how exercise can mitigate these consequences, and how to alter lifestyles to reduce sitting and increase movement and exercise.

The present study included 4,512 adults who were respondents of the 2003 Scottish Health Survey, a representative, household-based survey. A total of 325 all-cause deaths and 215 cardiac events occurred during an average of 4.3 years of follow up.

Measurement of"screen time" included self-reported TV/DVD watching, video gaming, as well as leisure-time computer use. Authors also included multiple measures to rule out the possibility that ill people spend more time in front of the screen as opposed to other way around. Authors excluded those who reported a previous cardiovascular event (before baseline) and those who died during the first two years of follow up just in case their underlying disease might have forced them to stay indoors and watch TV more often. Dr. Stamatakis and his team also adjusted analyses for indicators of poor health (e.g., diabetes, hypertension).

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Played by Humans, Scored by Nature, Online Game Helps Unravel Secrets of RNA

The game, called EteRNA harnesses game play to uncover principles for designing molecules of RNA, which biologists believe may be the key regulator of everything that happens in living cells. But the game doesn't end with the highest computer score. Rather, players are scored and ranked based on how well their virtual designs can be rendered as real, physical molecules. Each week's top designs are synthesized in a biochemistry laboratory so researchers can see if the resulting molecules fold themselves into the three-dimensional shapes predicted by computer models.

"Putting a ball through a hoop or drawing a better poker hand is the way we're used to winning games, but in EteRNA you score when the molecule you've designed can assemble itself," said Adrien Treuille, an assistant professor of computer science at Carnegie Mellon, who leads the EteRNA project with Rhiju Das, an assistant professor of biochemistry at Stanford."Nature provides the final score -- and nature is one tough umpire."

Because EteRNA is crowdsourcing the scientific method -- enlisting non-experts to uncover still-mysterious RNA design principles -- it is essential that scoring be rigorous.

"Nature confounds even our best computer models," said Jeehyung Lee, a computer science Ph.D. student at Carnegie Mellon who led the game's development."We knew that if we were to truly tap the wisdom of crowds, our game would have to expose players to every aspect of the scientific process: design, yes, but also experimentation, analysis of results and incorporation of those results into future designs."

The complex, three-dimensional shape of an RNA molecule is critical to its function. The goal of the EteRNA project is to design RNA knots, polyhedra and other shapes never seen before.

"We want to understand how RNA folds in a test tube and eventually in viruses and living cells," Das said."We also want to create a toolkit of basic building blocks that could be used to construct sensors, therapeutic agents and tiny machines."

By synthesizing a design generated by game play, researchers will learn quickly whether the resulting molecule folds into the predicted shape, or something close to it, or if it even folds at all. Even designs that are not synthesized will be scored by nature, in that their scores will be based on the performance of similar designs previously synthesized.

"These experiments are the first-line strategy for validating a design and a crucial part of the scientific method," said Das, whose lab at Stanford synthesizes the molecules."This makes EteRNA similar to what goes on in my lab on a daily basis: You make a prediction, do an experiment, make adjustments and start again." Initially, Das' lab is synthesizing eight designs each week, but is ramping up to synthesize about 100 a week.

RNA, or ribonucleic acid, long has been recognized as a messenger for genetic information, yet its role usually was overshadowed by DNA, which encodes genes, and by proteins, which do the work of the cell. But biologists now suspect RNA plays a much broader role as the regulator of cells, acting much like the operating system of a computer. Understanding RNA design could prove useful for treating or controlling such diseases as HIV, for creating RNA-based sensors and even for building computers out of RNA.

The game employs state-of-the-art simulation software that players use to generate designs. It includes training exercises and challenge puzzles for honing skills, as well as challenges for designing molecules that will be synthesized.

In its use of game play to generate results of scientific interest, EteRNA is similar to other online games such as Foldit, an online protein-folding game that Treuille helped create while at the University of Washington. In fact, Treuille and Das met when they sat at adjacent desks in the Washington biochemistry lab of David Baker, where Treuille was working on Foldit and Das was studying RNA and protein folding and occasionally offering advice.

Both men recognized that the lack of real-world feedback was a limitation of these games. They realized an RNA design game could solve this problem because RNA, unlike many biological molecules, can be readily synthesized in a matter of hours.

RNA consists of long, double strands of four bases -- adenine, guanine, cytosine and uracil -- with the shape determined by the sequence of the bases. The rules controlling shape are relatively simple, but the sheer size of the molecules greatly complicates the design process.

"We've already found it's better not to use regularly repeating sequences of bases because they prove unstable," Treuille said, based on play by beta testers."We're trying to build things that work in nature, and nature favors solutions that are robust."

The game is integrated with Facebook, so players can post accomplishments to their Facebook wall automatically and can create groups that talk about play and compete with each other.

The first challenges are relatively simple, arbitrary shapes, Das said, but will soon begin to incorporate designs of scientific relevance, such as RNA switches that could be used to sense and respond to other molecules in living cells.

Ultimately, players may end up creating designs and making discoveries of their own."They're already beginning to act like a scientific community," Treuille said."One player solved a puzzle that a widely used algorithm could not. Another player has written a strategy guide that proposes an algorithm for solving design problems that is different and simpler than anything in the scientific literature."

The EteRNA project is funded by a grant from the National Science Foundation.

For more information on EterRNA watch these video clips:

• What is the EteRNA game? (1:19)http://wms.andrew.cmu.edu:81/nmvideo/eterna_1.mov
• What have we learned from EteRNA? (1:57)http://wms.andrew.cmu.edu:81/nmvideo/eterna_2.mov 

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New System for Analyzing Information on WikiLeaks, Social Media

According to Josep Lluís Larriba, director of DAMA-UPC, the technology can be used to extract information from WikiLeaks from two perspectives: one, to obtain generic indicators that provide information on whether the data network has the features of a social network and whether communities of data are created that can provide relevant information; and two, to use the documents hosted on the website to analyze how a topic evolves over time, how a person or a group relates to different topics and how the documents themselves interrelate.

High-speed complex queries

The new DEX technology patented by the UPC can be used to explore large volumes of networked data. The system offers high-speed processing, configurable data entry from multiple sources, and the management of networks with billions of nodes and connections from a desktop PC.

Users can quickly and easily identify interrelated records by formulating queries based on simple values such as names and keywords. Until now, this was possible to a certain extent using database technology, but DEX extracts new information from interrelated data and improves the speed and the capacity to perform complex queries in large data networks.

The DAMA-UPC group, which sees huge potential for the technology in the field of social media and the internet, proposes using the DEX system to analyze data on WikiLeaks, the international media organization that publishes anonymous reports and leaked documents on its website.

From fraud detection to the evolution of cancer

In what was the first major application of DEX, the Notary Certification Agency (ANCERT) used the technology to detect fraud in real estate transactions and the Catalan Institute of Oncology is using it to study the evolution of cancer in Catalonia. The DAMA-UPC group is now looking into how DEX technology can be applied to pharmaceutical data analysis to explore developments in the use of medicines.

The group is also conducting research into how information spreads across the internet and at what speed, and why some news spreads faster than others. The project is developed in the framework of the Social Media project, a strategic industrial research project funded by the National Strategic Consortia for Technical Research (CENIT) program.

In the field of e-learning, the team is working on a project under the RecerCaixa grant program aimed at recommending and exploring audiovisual content for primary and secondary schools.

Exploring scientific information

In addition to the fields of health, fraud detection, education and the internet, the technology created by the DAMA-UPC group also offers benefits to the scientific world.

The group has designed BIBEX (www.dama.upc.edu/bibex), a unique prototype for the Spanish Ministry of Science and Innovation aimed at exploring scientific publications and relating specific literature published worldwide. BIBEX also offers other advantages: scientists can recommend scientific articles and find reviewers to evaluate scientific publications. In the future, BIBEX will offer a tool for businesses to find research groups that are working in common areas of interest.

Technology transfer

Sparsity Technologies (www.sparsity-technologies.com) is a spin-off that was created in 2010 with the participation of the UPC to promote and market the technologies developed by the DAMA-UPC group.

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