Posts about basic research

Pseudogap and Superconductivity

MIT physicists shed light on key superconductivity riddle

Hudson’s team is focusing on the state of matter that exists at temperatures just above the temperature at which materials start to superconduct. This state, known as the pseudogap, is poorly understood, but physicists have long believed that characterizing the pseudogap is important to understanding superconductivity.

In their latest work, published online on July 6 in Nature Physics, they suggest that the pseudogap is not a precursor to superconductivity, as has been theorized, but a competing state. If that is true, it could completely change the way physicists look at superconductivity, said Hudson.

“Now, if you want to explain high-temperature superconductivity and you believe the pseudogap is a precursor, you need to explain both. If it turns out that it is a competing state, you can instead focus more on superconductivity,” he said.

Related: Mystery of High-Temperature SuperconductivitySuperconducting SurpriseFlorida State lures Applied Superconductivity Center from Wisconsin

Measuring Protein Bond Strength with Optical Tweezers

Using a light touch to measure protein bonds

MIT researchers have developed a novel technique to measure the strength of the bonds between two protein molecules important in cell machinery: Gently tugging them apart with light beams. “It’s really giving us a molecular-level picture of what’s going on,” said Matthew Lang, an assistant professor of biological and mechanical engineering

The researchers studied the interactions between the proteins by pinning one actin filament to a surface and controlling the motion of the second one with a beam of light. As the researchers tug on a bead attached to the second filament, the bond mediated by the actin-binding protein eventually breaks.

With this technique, the researchers can get a precise measurement of the force holding the proteins together, which is on the order of piconewtons (10-12 newtons).

Related: Neuroengineers Use Light to Silence Overactive NeuronsSlowing Down LightFoldit, the Protein Folding Game

Exploring the Signaling Pathways of Cells

New probe may help untangle cells’ signaling pathways

MIT researchers have designed a new type of probe that can image thousands of interactions between proteins inside a living cell, giving them a tool to untangle the web of signaling pathways that control most of a cell’s activities.

“We can use this to identify new protein partners or to characterize existing interactions. We can identify what signaling pathway the proteins are involved in and during which phase of the cell cycle the interaction occurs,” said Alice Ting, the Pfizer-Laubach Career Development Assistant Professor of Chemistry and senior author of a paper describing the probe published online June 27 by the Journal of the American Chemical Society.

The new technique allows researchers to tag proteins with probes that link together like puzzle pieces if the proteins interact inside a cell. The probes are derived from an enzyme and its peptide substrate. If the probe-linked proteins interact, the enzyme and substrate also interact, which can be easily detected.

To create the probes, the researchers used the enzyme biotin ligase and its target, a 12-amino-acid peptide.

Related: Specific Protein and RNA Labeling in CellsUsing Bacteria to Carry Nanoparticles Into CellsMolecular Bioengineering and Dynamical Models of CellsThe Inner Life of a Cell (Animation)

Lancelet Genome Provides Answers on Evolution

Lancelet genome shows how genes quadrupled during vertebrate evolution by Robert Sanders

“If you compare the 23 chromosomes of humans with the 19 chromosomes of amphioxus, you find that both genomes can be expressed in terms of 17 ancestral pieces. So, we can say with some confidence that 550 million years ago, the common ancestor of amphioxus and humans had 17 chromosomal elements.”

Each of those 17 ancestral segments was duplicated twice in the evolution of vertebrates, after which most of the routine “housekeeping” genes lost the extra copies. Those left, totaling a couple thousand genes, found new functions that, Putnam said, make us different from all other creatures.

“These few thousand genes have been retooled to make humans more elaborate than their simpler ancestors. They are involved in setting up the body plan of an animal and differentiating different parts of the animal,” he said. “The hypothesis, pretty strongly supported by this data, is that the multiplication of this particular kind of gene and differentiation into different functions was important in the formation of vertebrates as we know them.”

“The most exciting thing that the amphioxus genome does is provide excellent evidence for the idea that Ono proposed in 1970, that the human genome had undergone two rounds of whole-genome duplication with subsequent losses,”

A great example of the scientific method in action. It often isn’t a matter of developing a theory one day, testing it the next and learning the outcome the next. The process can take decades for complex matters.

Related: Opossum Genome Shows ‘Junk’ DNA is Not JunkAmazing Science: Retrovirusesposts on evolution

Bacteria Evolutionary Shift Seen in the Lab

Bacteria make major evolutionary shift in the lab

A major evolutionary innovation has unfurled right in front of researchers’ eyes. It’s the first time evolution has been caught in the act of making such a rare and complex new trait. And because the species in question is a bacterium, scientists have been able to replay history to show how this evolutionary novelty grew from the accumulation of unpredictable, chance events.

sometime around the 31,500th generation, something dramatic happened in just one of the populations – the bacteria suddenly acquired the ability to metabolise citrate, a second nutrient in their culture medium that E. coli normally cannot use. Indeed, the inability to use citrate is one of the traits by which bacteriologists distinguish E. coli from other species.

The replays showed that even when he looked at trillions of cells, only the original population re-evolved Cit+ – and only when he started the replay from generation 20,000 or greater. Something, he concluded, must have happened around generation 20,000 that laid the groundwork for Cit+ to later evolve.

Lenski and his colleagues are now working to identify just what that earlier change was, and how it made the Cit+ mutation possible more than 10,000 generations later.

Related: People Have More Bacterial Cells than Human CellsUnderstanding the Evolution of Human Beings by CountryE. Coli Individuality

Materials Engineers Create Perfect Light “sponge”

Materials engineers create perfect light “sponge”

The team designed and engineered a metamaterial that uses tiny geometric surface features to successfully capture the electric and magnetic properties of a microwave to the point of total absorption.

“Three things can happen to light when it hits a material,” says Boston College Physicist Willie J. Padilla. “It can be reflected, as in a mirror. It can be transmitted, as with window glass. Or it can be absorbed and turned into heat. This metamaterial has been engineered to ensure that all light is neither reflected nor transmitted, but is turned completely into heat and absorbed. It shows we can design a metamaterial so that at a specific frequency it can absorb all of the photons that fall onto its surface.”

The metamaterial is the first to demonstrate perfect absorption and unlike conventional absorbers it is constructed solely out of metallic elements, giving the material greater flexibility for applications related to the collection and detection of light, such as imaging, says Padilla, an assistant professor of physics.

Related: Perfect Metamaterial Absorber letter (in Physical Review Letters) – Light to Matter to LightDelaying the Flow of Light on a Silicon ChipParticles and Wavesother posts linking to open access papers

At the Heart of All Matter

Large Hadron Collider at CERN

The hunt for the God particle by Joel Achenbach

Physics underwent one revolution after another. Einstein’s special theory of relativity (1905) begat the general theory of relativity (1915), and suddenly even such reliable concepts as absolute space and absolute time had been discarded in favor of a mind-boggling space-time fabric in which two events can never be said to be simultaneous. Matter bends space; space directs how matter moves. Light is both a particle and a wave. Energy and mass are inter- changeable. Reality is probabilistic and not deterministic: Einstein didn’t believe that God plays dice with the universe, but that became the scientific orthodoxy.

Most physicists believe that there must be a Higgs field that pervades all space; the Higgs particle would be the carrier of the field and would interact with other particles, sort of the way a Jedi knight in Star Wars is the carrier of the “force.” The Higgs is a crucial part of the standard model of particle physics—but no one’s ever found it.

The Higgs boson is presumed to be massive compared with most subatomic particles. It might have 100 to 200 times the mass of a proton. That’s why you need a huge collider to produce a Higgs—the more energy in the collision, the more massive the particles in the debris. But a jumbo particle like the Higgs would also be, like all oversize particles, unstable. It’s not the kind of particle that sticks around in a manner that we can detect—in a fraction of a fraction of a fraction of a second it will decay into other particles. What the LHC can do is create a tiny, compact wad of energy from which a Higgs might spark into existence long enough and vivaciously enough to be recognized.

Previous posts on CERN and the Higgs boson: The god of small thingsCERN Prepares for LHC OperationsCERN Pressure Test FailureThe New Yorker on CERN’s Large Hadron Collider

Electron Filmed for the First Time

Photo of electron movement

Now it is possible to see a movie of an electron. The movie shows how an electron rides on a light wave after just having been pulled away from an atom. This is the first time an electron has ever been filmed. Previously it has been impossible to photograph electrons since their extremely high velocities have produced blurry pictures. In order to capture these rapid events, extremely short flashes of light are necessary, but such flashes were not previously available.

With the use of a newly developed technology for generating short pulses from intense laser light, so-called attosecond pulses, scientists at the Lund University Faculty of Engineering in Sweden have managed to capture the electron motion for the first time. “It takes about 150 attoseconds for an electron to circle the nucleus of an atom. An attosecond is 10-18 seconds long, or, expressed in another way: an attosecond is related to a second as a second is related to the age of the universe,” says Johan Mauritsson, an assistant professor in atomic physics at the Faculty of Engineering, Lund University.

Scientists also hope to find out more about what happens with the rest of the atom when an inner electron leaves it, for instance how and when the other electrons fill in the gap that is created. “What we are doing is pure basic research. If there happen to be future applications, they will have to be seen as a bonus,” adds Johan Mauritsson. The length of the film corresponds to a single oscillation of the light, but the speed has then been ratcheted down considerably so that we can watch it. The filmed sequence shows the energy distribution of the electron and is therefore not a film in the usual sense.

Photo: Experimental results obtained in helium at an intensity of 1:2 x 1013 W=c/m2 are shown. The results are
distinctively different from those taken in argon (Fig. 1).With this higher intensity, more momentum is transferred to the electrons, and in combination with the lower initial energy, some electrons return to the atomic potential for further interaction. In the first panel, we compare the experimental results (right) with theoretical calculations (left) obtained for the same conditions.
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New Yorker on CERN’s Large Hadron Collider

Can a seventeen-mile-long collider unlock the universe?

A proton is a hadron composed of two up quarks and one down; a neutron consists of two downs and one up.) Fermions also include neutrinos, which, somewhat unnervingly, stream through our bodies at the rate of trillions per second.

The L.H.C., Doser explained, relies on much the same design, and, in fact, makes use of the tunnel originally dug for LEP. Instead of electrons and positrons, however, the L.H.C. will send two beams of protons circling in opposite directions. Protons are a good deal more massive than electrons—roughly eighteen hundred times more—which means they can carry more energy. For this reason, they are also much harder to manage.

“Basically, what you must have to accelerate any charged particles is a very strong electric field,” Doser said. “And the longer you apply it the more energy you can give them. In principle, what you’d want is an infinitely long linear structure, in which particles just keep getting pushed faster and faster. Now, because you can’t build an infinitely long accelerator, you build a circular accelerator.” Every time a proton makes a circuit around the L.H.C. tunnel, it will receive electromagnetic nudges to make it go faster until, eventually, it is travelling at 99.9999991 per cent of the speed of light. “It gets to a hair below the speed of light very rapidly, and the rest of the time is just trying to sliver down this hair.” At this pace, a proton completes eleven thousand two hundred and forty-five circuits in a single second.

Related: CERN Pressure Test FailureString Theory is Not Dead

CERN Pressure Test Failure

photo of Femilab inner triplet quadrupole at CERN

On March 27th a high-pressure test at CERN of a Fermilab-built ‘inner-triplet’ series of three quadrupole magnets in the tunnel of the Large Hadron Collider failed. Fermilab Director on the test failure:

We test the complex features we design thoroughly. In this case we are dumbfounded that we missed some very simple balance of forces. Not only was it missed in the engineering design but also in the four engineering reviews carried out between 1998 and 2002 before launching the construction of the magnets. Furthermore even though every magnet was thoroughly tested individually, they were never tested with the exact configuration that they would have when installed at CERN–thus missing the opportunity to discover the problem sooner.

We need and want to make sure that we find the root causes of the problem and from the lessons learned build a stronger institution. Beyond that, there is no substitute for the commitment each of us makes to excellence, to critical thinking and to sweating every detail.

In a Fermilab Update on Inner Triplet Magnets at LHC they state: “The goal at CERN and Fermilab is now to redesign and repair the inner triplet magnets and, if necessary, the DFBX without affecting the LHC start-up schedule. Teams at CERN and Fermilab have identified potential repairs that could be carried out expeditiously without removing undamaged triplet magnets from the tunnel.”

Related: Fermilab Statement on LHC Magnet Test FailureAccelerators and Nobel LaureatesFind the Root Cause Instead of the Person to Blame
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China and USA Basic Science Research

US$425 million to boost Chinese innovation by Fu Jing:

The National Natural Science Foundation of China will provide 3.4 billion yuan (US$425 million) in funding for basic science, it announced last week (25 May).

“The boost has shown the government’s determination for China to become an innovative country by 2020,” said the foundation’s vice-president Zhu Zuoyan. He added that the foundation’s research funding is set to grow by about 20 per cent a year for the next five years.

According to government plans, China’s total investment in science and technology should reach 2.5 per cent of its gross domestic product by 2020 — a share similar to that spent by industrialised nations.
By that time, China aims to be spending about US$112 billion annually on research and development (see China announces 58-point plan to boost science).

U.S. National Science Foundation Celebrates Opening of Beijing Office

The National Science Foundation is a U.S. government agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of $5.58 billion.

According to the NSF report, Science and Engineering Indicators 2006, China ranked fourth in the world in the year 2000 in research and development, with $48.9 billion in expenditures. Two years later, the country ranked third, behind the United States and Japan, spending an estimated $72.0 billion on R&D.

“It is important for the U.S. scientific community, especially young researchers, to be aware of and consider collaborating with colleagues in China in this environment,” said Beijing office Director William Chang.

The NSF Beijing Office is NSF’s third foreign office. NSF also maintains research offices in Paris and Tokyo.