Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Crowdsourcing the phase problem

18.06.2014

Compared with humans, computers have the capacity to solve problems at much greater speed.

There are many problems, however, where computational speed alone is insufficient to find a correct or optimal solution, for example because the parameter “space” cannot be fully searched in a practical time.

In contrast, the human mind can formulate expert knowledge specific for particular problems, providing a capacity to guide more efficient searches, although with more limited processing speed.

The power of the human contribution can be multiplied through the efforts of a greater number of individuals. The term `crowdsourcing', which combines the two domains of human and electronic computing, was coined in 2006 and since then has seen its definition broadened to a wide range of activities involving a network of people.

A challenging problem that might benefit from crowdsourcing is the phase problem in X-ray crystallography. Retrieving the phase information has plagued many scientists for decades when trying to determine the crystal structure of a sample.

In a diffraction experiment, the observed diffraction pattern allows measurement of the amplitudes of the reflection structure factors (as the square root of the intensities) but not their phases. The amplitudes and phases are both needed to reconstruct an electron-density map (by Fourier synthesis) so that a model of the crystallized molecule can be obtained.

There are a number of ways currently scientists try to solve the phase problem, all with varying degrees of success.

Regardless of the particular approach, most attacks on the phase problem can be viewed as having two sub-problems. One concerns how a high-dimensional space (i.e. of phases) can be efficiently searched, while the other concerns how a good solution can be recognized.

Crowdsourcing may be a route to solving these sub-problems [Jorda et al. (2014), Acta Cryst. D70, 1538-1548; doi:10.1107/S1399004714006427], here scientists have developed a game based on a genetic algorithm (a powerful search-optimization technique), where players control the selection mechanism during the evolutionary process (by recognising the good solutions).

The algorithm starts from a population of “individuals”, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals.

The game called CrowdPhase (http://www.crowdphase.com) was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30 degree phase error range and corresponding molecular envelopes showing agreement with the low-resolution models.

Successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it possible to extract meaningful information in cases where limited resolution might otherwise prevent initial phasing.

Jonathan Agbenyega
Business Development Manager, IUCr 

Dr. Jonathan Agbenyega | Eurek Alert!
Further information:
http://www.iucr.org/news/research-news/crowdsourcing-the-phase-problem

Further reports about: Crowdsourcing Crystallography Darwinian X-ray activities algorithm problems structure synthesis synthetic

More articles from Information Technology:

nachricht LAMA 2.0 accelerates more than just numerical applications
21.06.2016 | Fraunhofer-Institut für Algorithmen und Wissenschaftliches Rechnen SCAI

nachricht Researchers open hairy new chapter in 3-D printing
20.06.2016 | Massachusetts Institute of Technology

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First experimental quantum simulation of particle physics phenomena

Physicists in Innsbruck have realized the first quantum simulation of lattice gauge theories, building a bridge between high-energy theory and atomic physics. In the journal Nature, Rainer Blatt‘s and Peter Zoller’s research teams describe how they simulated the creation of elementary particle pairs out of the vacuum by using a quantum computer.

Elementary particles are the fundamental buildings blocks of matter, and their properties are described by the Standard Model of particle physics. The...

Im Focus: Is There Life On Mars?

Survivalist back from Space - 18 months on the outer skin of the ISS

A year and a half on the outer wall of the International Space Station ISS in altitude of 400 kilometers is a real challenge. Whether a primordial bacterium...

Im Focus: CWRU physicists deploy magnetic vortex to control electron spin

Potential technology for quantum computing, keener sensors

Researchers at Case Western Reserve University have developed a way to swiftly and precisely control electron spins at room temperature.

Im Focus: Physicists measured something new in the radioactive decay of neutrons

The experiment inspired theorists; future ones could reveal new physics

A physics experiment performed at the National Institute of Standards and Technology (NIST) has enhanced scientists' understanding of how free neutrons decay...

Im Focus: Discovery of gold nanocluster 'double' hints at other shape changing particles

New analysis approach brings two unique atomic structures into focus

Chemically the same, graphite and diamonds are as physically distinct as two minerals can be, one opaque and soft, the other translucent and hard. What makes...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ERES 2016: The largest conference in the European real estate industry

09.06.2016 | Event News

Networking 4.0: International Laser Technology Congress AKL’16 Shows New Ways of Cooperations

24.05.2016 | Event News

Challenges of rural labor markets

20.05.2016 | Event News

 
Latest News

Nanoscientists develop the 'ultimate discovery tool'

24.06.2016 | Materials Sciences

Russian physicists create a high-precision 'quantum ruler'

24.06.2016 | Physics and Astronomy

Hubble confirms new dark spot on Neptune

24.06.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>