Neutrons Provide First Sub-Nanoscale Snapshots of Huntington's Disease Protein

Huntington's disease is caused by a renegade protein"huntingtin" that destroys neurons in areas of the brain concerned with the emotions, intellect and movement. All humans have the normal huntingtin protein, which is known to be essential to human life, although its true biological functions remain unclear.

Christopher Stanley, a Shull Fellow in the Neutron Scattering Science Division at ORNL, and Valerie Berthelier, a UT Graduate School of Medicine researcher who studies protein folding and misfolding in Huntington's, have used a small-angle neutron scattering instrument, called Bio-SANS, at ORNL's High Flux Isotope Reactor to explore the earliest aggregate species of the protein that are believed to be the most toxic.

Stanley and Berthelier, in research published inBiophysical Journal, were able to determine the size and mass of the mutant protein structures―from the earliest small, spherical precursor species composed of two (dimers) and three (trimers) peptides―along the aggregation pathway to the development of the resulting, later-stage fibrils. They were also able to see inside the later-stage fibrils and determine their internal structure, which provides additional insight into how the peptides aggregate.

"Bio-SANS is a great instrument for taking time-resolved snapshots. You can look at how this stuff changes as a function of time and be able to catch the structures at the earliest of times," Stanley said."When you study several of these types of systems with different glutamines or different conditions, you begin to learn more and more about the nature of these aggregates and how they begin forming."

Normal huntingtin contains a region of 10 to 20 glutamine amino acids in succession. However, the DNA of Huntington's disease patients encodes for 37 or more glutamines, causing instability in huntingtin fragments that contain this abnormally long glutamine repeat. Consequentially, the mutant protein fragment cannot be degraded normally and instead forms deposits of fibrils in neurons.

Those deposits, or clumps, were originally seen as the cause of the devastation that ensues in the brain. More recently researchers think the clumping may actually be a kind of biological housecleaning, an attempt by the brain cells to clean out these toxic proteins from places where they are destructive. Stanley and Berthelier set out to learn through neutron scattering what the toxic proteins were and when and where they occurred.

At the HFIR Bio-SANS instrument, the neutron beam comes through a series of mirrors that focus it on the sample. The neutrons interact with the sample, providing data on its atomic structure, and then the neutrons scatter, to be picked up by a detector. From the data the detector sends of the scattering pattern, researchers can deduce at a scale of less than billionths of a meter the size and shape of the diseased, aggregating protein, at each time-step along its growth pathway.

SANS was able to distinguish the small peptide aggregates in the sample solution from the rapidly forming and growing larger aggregates that are simultaneously present. In separate experiments, they were able to monitor the disappearance of the single peptides, as well as the formation of the mature fibrils.

Now that they know the structures, the hope is to develop drugs that can counteract the toxic properties in the early stages, or dissuade them from taking the path to toxicity."The next step would be, let's take drug molecules and see how they can interact and affect these structures," Stanley said.

For now, the researchers believes Bio-SANS will be useful in the further study of Huntington's disease aggregates and applicable for the study of other protein aggregation processes, such as those involved in Alzheimer's and Parkinson's diseases.

"That is the future hope. Right now, we feel like we are making a positive contribution towards that goal," Stanley said.

The research was supported by the National Institutes of Health. HFIR and Bio-SANS are supported by the DOE Office of Science.

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Controling Robotic Arms Is Child's Play

"The input device contains various movement sensors, also called inertial sensors," says Bernhard Kleiner of the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart, who leads the project. The individual micro-electromechanical systems themselves are not expensive. What the scientists have spent time developing is how these sensors interact."We have developed special algorithms that fuse the data of individual sensors and identify a pattern of movement. That means we can detect movements in free space," summarizes Kleiner.

What may at first appear to be a trade show gimmick, is in fact a technology that offers numerous advantages in industrial production and logistical processes. The system could be used to simplify the programming of industrial robots, for example. To date, this has been done with the aid of laser tracking systems: An employee demonstrates the desired motion with a hand-held baton that features a white marker point. The system records this motion by analyzing the light reflected from a laser beam aimed at the marker. Configuring and calibrating the system takes a lot of time. The new input device should eliminate the need for these steps in the future -- instead, employees need only pick up the device and show the robot what it is supposed to do.

The system has numerous applications in medicine, as well. Take, for example, gait analysis. Until now, cameras have made precise recordings of patients as they walk back and forth along a specified path. The films reveal to the physician such things as how the joints behave while walking, or whether incorrect posture in the knees has been improved by physical therapy. Installing the cameras, however, is complex and costly, and patients are restricted to a predetermined path. The new sensor system can simplify this procedure: Attached to the patient's upper thigh, it measures the sequences and patterns of movement -- without limiting the patient's motion in any way.

"With the inertial sensor system, gait analysis can be performed without a frame of reference and with no need for a complex camera system," explains Kleiner. In another project, scientists are already working on comparisons of patients' gait patterns with those patterns appearing in connection with such diseases as Parkinson's.

Another medical application for the new technology is the control of active prostheses containing numerous small actuators. Whenever the patient moves, the prosthesis in turn also moves; this makes it possible for a leg prosthesis to roll the foot while walking. Here, too, the sensor could be attached to the patient's upper thigh and could analyze the movement, helping to regulate the motors of the prosthesis. Research scientists are currently working on combining the inertial sensor system with an electromyographic (EMG) sensor. Electromyography is based on the principle that when a muscle tenses, it produces an electrical voltage which a sensor can then measure by way of an electrode. If the sensor is placed, for example, on the muscle responsible for lifting the patient's foot, the sensor registers when the patient tenses this muscle -- and the prosthetic foot lifts itself. EMG sensors like this are already available but are difficult to position.

"While standard EMG sensors consist of individual electrodes that have to be positioned precisely on the muscle, our system is made up of many small electrodes that attach to a surface area. This enables us to sense muscle movements much more reliably," says Kleiner.

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Scientists Achieve Guiding of Electrons by Purely Electric Fields

The research is published online inPhysical Review Letters.

This new technique of electron guiding -- which resembles the guiding of light waves in optical fibres -- promises a variety of applications, from guided matter-wave experiments to non-invasive electron microscopy.

Electrons have been the first elementary particles revealing their wave-like properties and have therefore been of great importance in the development of the theory of quantum mechanics. Even now the observation of electrons leads to new insight into the fundamental laws of physics. Measurements involving confined electrons have so far mainly been performed in so-called Penning traps, which combine a static magnetic field with an oscillating electric field.

For a number of experiments with propagating electrons, like interferometry with slow electrons, it would be advantageous to confine the electrons by a purely electric field. This can be done in an alternating quadrupole potential similar to the standard technique that is used for ion trapping. These so-called Paul traps are based on four electrodes to which a radiofrequency voltage is applied. The resulting field evokes a driving force which keeps the particle in the centre of the trap. Wolfgang Paul received the Nobel Prize in physics for the invention of these traps in 1989.

For several years by now scientists realize Paul traps with micro structured electrodes on planar substrates, using standard microelectronic chip technology. Dr. Hommelhoff and his group have now applied this method for the first time to electrons. Since the mass of these point-like particles is only a tenth of a thousandth of the mass of an ion, electrons react much faster to electric fields than the rather heavy ions. Hence, in order to guide electrons, the frequency of the alternating voltage applied to the electrodes has to be much higher than for the confinement of ions and is in the microwave range, at around 1 GHz.

In the experiment electrons are generated in a thermal source (in which a tungsten wire is heated like in a light bulb) and the emitted electrons are collimated to a parallel beam of a few electron volts. From there the electrons are injected into the"wave-guide." It is being generated by five electrodes on a planar substrate to which an alternating voltage with a frequency of about 1 GHz is applied. This introduces an oscillating quadrupole field in a distance of half a millimetre above the electrodes, which confines the electrons in the radial direction. In the longitudinal direction there is no force acting on the particles so that they are free to travel along the"guide tube." As the confinement in the radial direction is very strong the electrons are forced to follow even small directional changes of the electrodes.

In order to make this effect more visible the 37mm long electrodes are bent to a curve of 30 degrees opening angle and with a bending radius of 40mm. At the end of the structure the guided electrons are ejected and registered by a detector. A bright spot caused by guided electrons appears on the detector right at the exit of the guide tube, which is situated in the left part of the picture. When the alternating field is switched off a more diffusively illuminated area shows up on the right side. It is caused by electrons spreading out from the source and propagating on straight trajectories over the substrate.

"With this fundamental experiment we were able to show that electrons can be efficiently guided be purely electric fields," says Dr. Hommelhoff."However, as our electron source yields a rather poorly collimated electron beam we still lose many electrons." In the future the researchers plan to combine the new microwave guide with an electron source based on field emission from an atomically sharp metal tip. These devices deliver electron beams with such a strong collimation that their transverse component is limited by the Heisenberg uncertainty principle only.

Under these conditions it should be feasible to investigate the individual quantum mechanical oscillations of the electrons in the radial potential of the guide."The strong confinement of electrons observed in our experiment means that a"jump" from one quantum state to the neighbouring higher state requires a lot of energy and is therefore not very likely to happen," explains Johannes Hoffrogge, doctoral student at the experiment."Once a single quantum state is populated it will remain so for an extended period of time and can be used for quantum experiments." This would make it possible to conduct quantum physics experiments such as interferometry with guided slow electrons. Here the wave function of an electron is first split up; later on, its two components are brought together again whereby characteristic superpositions of quantum states of the electron can be generated. But the new method could also be applied for a new form of electron microscopy.

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Antibody-Based Biosensor Can Guide Environmental Clean-Ups, Provide Early Warning System for Spills

Testing of the biosensor in the Elizabeth River and Yorktown Creek, which both drain into lower Chesapeake Bay, shows that the instrument can process samples in less than 10 minutes, detect pollutants at levels as low as just a few parts per billion, and do so at a cost of just pennies per sample. Current technology requires hours of lab work, with a per-sample cost of up to$1,000.

"Our biosensor combines the power of the immune system with the sensitivity of cutting-edge electronics," says Dr. Mike Unger of VIMS."It holds great promise for real-time detection and monitoring of oil spills and other releases of contaminants into the marine environment."

The biosensor was developed and tested by Unger, fellow VIMS professor Steve Kaattari, and their doctoral student Candace Spier, with assistance from marine scientist George Vadas. The team's report of field tests with the sensor appears in this month's issue ofEnvironmental Toxicology and Chemistry.

The instrument was developed in conjunction with Sapidyne Instruments, Inc., with funding from the state of Virginia, the Office of Naval Research, and the Cooperative Institute for Coastal and Estuarine Environmental Technology, a partnership between NOAA and the University of New Hampshire.

The tests in the Elizabeth River took place during clean up of a site contaminated by polycyclic aromatic hydrocarbons (PAHs), byproducts of decades of industrial use of creosote to treat marine pilings. The U.S. Environmental Protection Agency considers PAHs highly toxic and lists 17 as suspected carcinogens.

The biosensor allowed the researchers to quantify PAH concentrations while the Elizabeth River remediation was taking place, gaining on-site knowledge about water quality surrounding the remediation site. Spier says the test was"the first use of an antibody-based biosensor to guide sampling efforts through near real-time evaluation of environmental contamination."

In the Yorktown Creek study, the researchers used the biosensor to track the runoff of PAHs from roadways and soils during a rainstorm.

Biosensor development

Kaattari says"Our basic idea was to fuse two different kinds of technologies -- monoclonal antibodies and electronic sensors -- in order to detect contaminants."

Antibodies are proteins produced by the immune system of humans and other mammals. They are particularly well suited for detecting contaminants because they have, as Kaattari puts it, an"almost an infinite power to recognize the 3-dimensional shape of any molecule."

Mammals produce antibodies that recognize and bind with large organic molecules such as proteins or with viruses. The VIMS team took this process one step further, linking proteins to PAHs and other contaminants, then exposing mice to these paired compounds in a manner very similar to a regular vaccination.

"Just like you get vaccinated against the flu, we in essence are vaccinating our mice against contaminants," says Kaattari."The mouse's lymphatic system then produces antibodies to PAHs, TNT, tributyl tin {TBT, the active ingredient in anti-fouling paints for boats}, or other compounds."

Once a mouse has produced an antibody to a particular contaminant, the VIMS team applies standard clinical techniques to produce"monoclonal antibodies" in sufficiently large quantities for use in a biosensor.

"This technology allows you to immortalize a lymphocyte that produces only a very specific antibody," says Kaattari."You grow the lymphocytes in culture and can produce large quantities of antibodies within a couple of weeks. You can preserve the antibody-producing lymphocyte forever, which means you don't have to go to a new animal every time you need to produce new antibodies."

From antibody to electrical signal

The team's next step was to develop a sensor that can recognize when an antibody binds with a contaminant and translate that recognition into an electrical signal. The Sapidyne^®sensor used by the VIMS team works via what Kaattari calls a"fluorescence-inhibitory, spectroscopic kind of assay."

In the sensor used on the Elizabeth River and Yorktown Creek, antibodies designed to recognize a specific class of PAHs were joined with a dye that glows when exposed to fluorescent light. The intensity of that light is in turn recorded as a voltage. The sensor also houses tiny plastic beads that are coated with what Spier calls a"PAH surrogate" -- a PAH derivative that retains the shape that the antibody recognizes as a PAH molecule.

When water samples with low PAH levels are added to the sensor chamber (which is already flooded with a solution of anti-PAH antibodies), the antibodies have little to bind with and are thus free to attach to the surrogate-coated beads, providing a strong fluorescent glow and electric signal. In water samples with high PAH concentrations, on the other hand, a large fraction of the antibodies bind with the environmental contaminants. That leaves fewer to attach to the surrogate-coated beads, which consequently provides a fainter glow and a weaker electric signal.

During the Elizabeth River study, the biosensor measured PAH concentrations that ranged from 0.3 to 3.2 parts per billion, with higher PAH levels closer to the dredge site. In Yorktown Creek, the biosensor showed that PAH levels in runoff peaked 1 to 2 hours after the rain started, with peak concentration of 4.4 parts per billion.

Comparison of the biosensor's field readings with later readings from a mass spectrometer at VIMS showed that the biosensor is just as accurate as the more expensive, slower, and laboratory-bound machine.

A valuable field tool

Spier says"Using the biosensor allowed us to quickly survey an area of almost 900 acres around the Elizabeth River dredge, and to provide information about the size and intensity of the contaminant plume to engineers monitoring the dredging from shore. If our results had shown elevated concentrations, they could have halted dredging and put remedial actions in place."

Unger adds"measuring data in real-time also allowed us to guide the collection of large-volume water samples right from the boat. We used these samples for later analysis of specific PAH compounds in the lab. This saved time, effort, and money by keeping us from having to analyze samples that might contain PAHs at levels below our detection limit."

"Biosensors have their constraints and optimal operating conditions," says Kaattari,"but their promise far outweighs any limitations. The primary advantages of our biosensor are its sensitivity, speed, and portability. These instruments are sure to have a myriad of uses in future environmental monitoring and management."

One promising use of the biosensor is for early detection and tracking of oil spills."If biosensors were placed near an oil facility and there was a spill, we would know immediately," says Kaattari."And because we could see concentrations increasing or decreasing in a certain pattern, we could also monitor the dispersal over real time."

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Far Sighted Space Technology Finds Practical Uses on Earth

Ken Wood is presenting the project at the RAS National Astronomy Meeting in Llandudno, Wales.

The part of the Electromagnetic Spectrum including the far infra red and microwave is also called 'terahertz' radiation. Astronomers use this kind of radiation to study the Cosmic Microwave Background and the huge dust clouds where stars are born. The sensitive detectors they use will only operate at temperatures very close to absolute zero (minus 273C.) In Terahertz cameras like KIDCAM, those low temperatures are accessible in compact and less expensive ways using relatively new cooler technology. KIDCAM therefore has many potential day-to-day applications.

"We are all familiar with optical images of the surface of objects and X-ray images which penetrate through soft tissue to reveal bone structure. Terahertz observations give us something in between the two. For example, most clothing and packaging materials are transparent to Terahertz radiation, whereas skin, water, metal and a host of other interesting materials are not. This gives rise to some important day-to-day applications: detecting weapons concealed under clothing or inside parcels; distinguishing skin and breast cancer tissue; quality control of manufactures items and processes in factories. Our KIDCAM detectors are also very sensitive, and so we can look at the natural radiation emitted by the target. This means there are no safety issues like those associated with other imaging techniques which shine radiation, including X-rays, at the target," said Mr Wood.

Until recently, there have been many practical obstacles to using terahertz detectors. Terahertz sources have only become available to the non-specialist in the last 10 years and cooling the detectors to very low temperatures using liquid cryogens is costly and complicated.

"The instruments aboard the Herschel and Planck satellites need to be cooled to temperatures close to absolute zero so that emissions from the spacecraft don't drown out the faint signals that come from the very edge of the observable Universe," said Ken Wood.

"For KIDCAM, we have developed a kind of detector that can be operated in electrical coolers and therefore without the use of liquified gases. KIDCAM can be tuned to specific frequencies for specific applications, for instance to enhance the contrast between skin and plastic explosive for airport security scanners. Unwanted frequencies can be blocked to increase the camera's sensitivity. The experience that we gained working on astronomical missions has been invaluable in helping us do this. The race is now on around the world to produce devices that will realise the enormous potential of terahertz science and thanks to the ingenuity of UK astronomers we have made a great start."

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New Biosensor Microchip Could Speed Up Drug Development, Researchers Say

A single centimeter-sized array of the nanosensors can simultaneously and continuously monitor thousands of times more protein-binding events than any existing sensor. The new sensor is also able to detect interactions with greater sensitivity and deliver the results significantly faster than the present"gold standard" method.

"You can fit thousands, even tens of thousands, of different proteins of interest on the same chip and run the protein-binding experiments in one shot," said Shan Wang, a professor of materials science and engineering, and of electrical engineering, who led the research effort.

"In theory, in one test, you could look at a drug's affinity for every protein in the human body," said Richard Gaster, MD/PhD candidate in bioengineering and medicine, who is the first author of a paper describing the research that is in the current issue ofNature Nanotechnology,available online now.

The power of the nanosensor array lies in two advances. First, the use of magnetic nanotags attached to the protein being studied -- such as a medication -- greatly increases the sensitivity of the monitoring.

Second, an analytical model the researchers developed enables them to accurately predict the final outcome of an interaction based on only a few minutes of monitoring data. Current techniques typically monitor no more than four simultaneous interactions and the process can take hours.

"I think their technology has the potential to revolutionize how we do bioassays," said P.J. Utz, associate professor of medicine (immunology and rheumatology) at Stanford University Medical Center, who was not involved in the research.

A microchip with a nanosensor array (orange squares) is shown with a different protein (various colors) attached to each sensor. Four proteins of a potential medication (blue Y-shapes), with magnetic nanotags attached (grey spheres), have been added. One medication protein is shown binding with a protein on a nanosensor.

Members of Wang's research group developed the magnetic nanosensor technology several years ago and demonstrated its sensitivity in experiments in which they showed that it could detect a cancer-associated protein biomarker in mouse blood at a thousandth of the concentration that commercially available techniques could detect. That research was described in a 2009 paper inNature Medicine.

The researchers tailor the nanotags to attach to the particular protein being studied. When a nanotag-equipped protein binds with another protein that is attached to a nanosensor, the magnetic nanotag alters the ambient magnetic field around the nanosensor in a small but distinct way that is sensed by the detector.

"Let's say we are looking at a breast cancer drug," Gaster said."The goal of the drug is to bind to the target protein on the breast cancer cells as strongly as possible. But we also want to know: How strongly does that drug aberrantly bind to other proteins in the body?"

To determine that, the researchers would put breast cancer proteins on the nanosensor array, along with proteins from the liver, lungs, kidneys and any other kind of tissue that they are concerned about. Then they would add the medication with its magnetic nanotags attached and see which proteins the drug binds with -- and how strongly.

"We can see how strongly the drug binds to breast cancer cells and then also how strongly it binds to any other cells in the human body such as your liver, kidneys and brain," Gaster said."So we can start to predict the adverse affects to this drug without ever putting it in a human patient."

It is the increased sensitivity to detection that comes with the magnetic nanotags that enables Gaster and Wang to determine not only when a bond forms, but also its strength.

"The rate at which a protein binds and releases, tells how strong the bond is," Gaster said. That can be an important factor with numerous medications.

"I am surprised at the sensitivity they achieved," Utz said."They are detecting on the order of between 10 and 1,000 molecules and that to me is quite surprising."

The nanosensor is based on the same type of sensor used in computer hard drives, Wang said.

"Because our chip is completely based on existing microelectronics technology and procedures, the number of sensors per area is highly scalable with very little cost," he said.

Although the chips used in the work described in theNature Nanotechnologypaper had a little more than 1,000 sensors per square centimeter, Wang said it should be no problem to put tens of thousands of sensors on the same footprint.

"It can be scaled to over 100,000 sensors per centimeter, without even pushing the technology limits in microelectronics industry," he said.

Wang said he sees a bright future for increasingly powerful nanosensor arrays, as the technology infrastructure for making such nanosensor arrays is in place today.

"The next step is to marry this technology to a specific drug that is under development," Wang said."That will be the really killer application of this technology."

Other Stanford researchers who participated in the research and are coauthors of theNature Nanotechnologypaper are Liang Xu and Shu-Jen Han, both of whom were graduate students in materials science and engineering at the time the research was done; Robert Wilson, senior scientist in materials science and engineering; and Drew Hall, graduate student in electrical engineering. Other coauthors are Drs. Sebastian Osterfeld and Heng Yu from MagArray Inc. in Sunnyvale. Osterfeld and Yu are former alumni of the Wang Group.

Funding for the research came from the National Cancer Institute, the National Science Foundation, the Defense Advanced Research Projects Agency, the Gates Foundation and National Semiconductor Corporation.

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Search for Dark Matter Moves One Step Closer to Detecting Elusive Particle

Their new results, announced April 14 at the Gran Sasso National Laboratory in Italy, where the XENON experiment is housed deep beneath a mountain 70 miles west of Rome, represent the highest-sensitivity search for dark matter yet, with background noise 100 times lower than competing efforts.

Dark matter is widely thought to be a kind of massive elementary particle that interacts weakly with ordinary matter. Physicists refer to these particles as WIMPS, for weakly interacting massive particles. The XENON researchers used a dark-matter detector known as XENON100 -- an instrumented vat filled with over 100 pounds of liquid xenon -- as a target for these WIMPs, which are thought to be streaming constantly through the solar system and Earth.

And while the XENON100 experiment found no dark matter signal in 100 days of testing, the researchers' newly calculated upper limits on the mass of WIMPs and the probability of their interacting with other particles are the best in the world, said UCLA physics professor Katsushi Arisaka, a member of the international collaboration.

XENON100 looks for a primary flash of light that occurs when a particle bounces off a xenon atom inside the detector and a secondary flash when an electron knocked free from a xenon atom by a collision is accelerated toward the top of the device by an electric field, said UCLA physics researcher Hanguo Wang, who works closely with Arisaka. With this configuration, a WIMP will generate a signal fundamentally different from that of cosmic radiation or emission from the equipment itself, making it possible to identify background readings that could be mistaken for a positive detection, he said.

Even though the experiment did not detect a WIMP, the progress sets the stage for an ambitious next-generation project called XENON1T, which will use a much larger, one-ton liquid xenon instrument with highly specialized light-detectors developed at UCLA that make it 100 times more sensitive than XENON100, said David Cline, a UCLA professor of physics and founder of UCLA's dark matter group.

The search for dark matter

Ordinary matter, which makes up the stars, planets, gas and dust in our galaxy, emits or reflects light that can be observed using telescopes on Earth or in space. However, the effect of dark matter, according to several theories, can be observed only indirectly by the gravitational force exerted on the more visible portions of the galaxy around us, Cline said.

Despite the differences between ordinary and dark matter, cosmologists believe the two have been linked since the beginning of the universe, with dark matter playing a key role in the coalescing of particles into stars, galaxies and other large-scale structures after the Big Bang.

Though dark matter exerts a tangible force on the galaxy as a whole, individual WIMPs have proved far more difficult to detect. Because these particles interact only very weakly with normal matter, the small signal that might come from a WIMP detection above ground would be drowned out by the cosmic radiation that constantly bombards Earth's surface, Cline said.

To eliminate the majority of this background noise, the XENON100 experiment is buried beneath almost one mile of rock in the Gran Sasso lab, the largest underground facility of its kind in the world. While dark matter particles can travel easily through the vast expanse of stone and pass through the detector, only the most energetic particles from space are able to follow, Arisaka said.

Next steps

Because the XENON100 experiment is shielded by large amounts of rock, as well as by several tons of copper, lead and water, the largest source of background detections is actually the radiation coming from the instrument itself, Arisaka said.

In an effort to address this issue, Arisaka and Wang, working in collaboration with Hamamatsu Photonics in Japan, have developed the Quartz Photon Intensifying Detector (QUPID), a new light-detector technology that emits no radiation. The XENON group hopes to incorporate this breakthrough technology into the future XENON1T experiment.

"We have developed a detector to be used in future experiments based on new photon-detector technology," Wang said."We invented, tested and demonstrated its operation in liquid xenon in our laboratory at UCLA."

In addition to Arisaka, Cline and Wang, UCLA's XENON group includes postdoctoral scholars Emilija Pantic and Paolo Beltrame and graduate students Artin Teymourian and Kevin Lung. Two students, Ethan Brown and Michael Lam, received doctorates last year through this experiment.

Elena Aprile, a professor of physics at Columbia University, is the XENON collaboration's principal investigator and spokesperson.

The XENON collaboration consists of 60 scientists from 14 institutions in the U.S. (UCLA, Columbia University, Rice University); China (Shanghai Jiao Tong University); France (Subatech Nantes); Germany (Max-Planck-Institut Heidelberg, Johannes Gutenberg University Mainz, Willhelms Universität Münster); Israel (Weizmann Institute of Science); Italy (Laboratori Nazionali del Gran Sasso, INFN e Università di Bologna); the Netherlands (Nikhef Amsterdam); Portugal (Universidade de Coimbra); and Switzerland (Universität Zürich).

XENON100 is supported by its collaborating institutions and federally funded by the National Science Foundation and the U.S. Department of Energy, as well as by the Swiss National Foundation; France's Institut national de physique des particules et de physique nucléaire and La Région des Pays de la Loire; Germany's Max-Planck-Society and Deutsche Forschungsgemeinschaft; Israel's German-Israeli Minerva Gesellschaft and GIF; the Netherlands' FOM; Portugal's Fundação para a Ciência e Tecnologia; Italy's Instituto Nazionale di Fisica Nucleare; and China's STCSM.

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