Physicist tests theories of dark energy by mimicking the vacuum of space

Besides the atoms that make up our bodies and all of the objects we encounter in everyday life, the universe also contains mysterious dark matter and dark energy. The latter, which causes galaxies to accelerate away from one another, constitutes the majority of the universe’s energy and mass.

Ever since dark energy was discovered in 1998, scientists have been proposing theories to explain it—one is that dark energy produces a force that can be measured only where space has a very low density, like the regions between galaxies.

Paul Hamilton, a Univ. of California, Los Angeles (UCLA) assistant professor of physics and astronomy, reproduced the low-density conditions of space to precisely measure this force. His findings, which helped to reveal how strongly dark energy interacts with normal matter, appear online in Science.

Hamilton’s research focuses on the search for specific types of dark energy fields known as “chameleon fields,” which exhibit a force whose strength depends on the density of their surrounding environment. This force, if it were proven to exist, would be an example of a so-called “fifth force” beyond the four known forces of gravity, electromagnetism, and the strong and weak forces acting within atoms.

But this fifth force has never been detected in laboratory experiments, which prompted physicists to propose that when chameleon fields are in dense regions of space—for example, the Earth’s atmosphere—they shrink so dramatically that they become immeasurable.

Chameleon fields were first hypothesized in 2004 by Justin Khoury, a Univ. of Pennsylvania physicist and co-author of the Science paper, but it wasn’t until 2014 that English physicist Clare Burrage and colleagues proposed a methodology for testing their existence in a laboratory using atoms.

At the time, Hamilton was a postdoctoral researcher in the UC Berkeley laboratory of Holger Müller. His team already had a head start on investigating chameleon fields: They had independently developed an experiment using atoms to measure small forces.

Detecting the force of chameleon fields requires replicating the vacuum of space, Hamilton explained, because when they are near mass, the fields essentially hide. So the physicists built a vacuum chamber, roughly the size of a soccer ball, in which the pressure was one-trillionth that of the atmosphere we normally breathe. The researchers inserted atoms of cesium, a soft metal, into the vacuum chamber to detect forces.

“Atoms are the perfect test particles; they don’t weigh very much and they’re very small,” Hamilton said.

They also added to the vacuum chamber an aluminum sphere roughly the size of a marble, which functioned as a dense object to suppress the chameleon fields and allow the researchers to measure small forces. The atoms were then cooled to within 10 one-millionths of a degree above absolute zero, in order to keep them still enough for the scientists to perform the experiment.

Hamilton and his team collected data by shining a near-infrared laser into the vacuum chamber and measuring how the cesium atoms accelerated due to gravity and, potentially, another force.

“We used a light wave as a ruler to measure the acceleration of atoms,” Hamilton said.

This measurement was performed twice: once when the aluminum sphere was close to the atoms and once when it was farther away. According to scientific theory, chameleon fields would cause the atoms to accelerate differently depending on how far away the sphere was.

The researchers found no difference in the acceleration of the cesium atoms when they changed the location of the aluminum sphere. As a result, the researchers now have a better understanding of how strongly chameleon fields can interact with normal matter, but Hamilton will continue to use cold atoms to investigate theories of dark energy. His next experiment will aim to detect other possible forms of dark energy that cause forces that change with time.



Source: Univ. of California, Los Angeles

Carbon number crunching

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A booming economy and population led China to emerge in 2006 as the global leader in fossil-fuel carbon emissions, a distinction it still maintains. But exactly how much carbon China releases has been a topic of debate, with recent estimates varying by as much as 15%.

“There’s great scrutiny of Chinese emissions now that they are the world’s largest fossil-fuel emitter,” said Tom Boden from the U.S. Dept. of Energy (DOE)’s Oak Ridge National Laboratory (ORNL). “Their economy has grown at such a fast rate, so naturally a lot of attention has turned to their emission estimates.”

As director of the Carbon Dioxide Information Analysis Center (CDIAC) at ORNL, Boden has been tracking the world’s carbon emissions for the past 25 years. CDIAC’s annual inventory of carbon released from fossil fuels by country has become a benchmark dataset for climate change scientists and policymakers.

Boden, ORNL’s Bob Andres, and Appalachian State Univ.’s Gregg Marland, a former ORNL scientist, recently lent their emissions data expertise to a new Nature study that reevaluated China’s emissions from 2000 to 2013. The study, led by Zhu Liu of Harvard Univ., illustrates how carbon emissions estimates take into account a complex set of variables.

“The fundamental calculation requires knowledge of the amount of fuel consumed and the efficiency of burning or the oxidation rate, but you also have to know the carbon content of the fuel,” Boden said. “The carbon content of coal is different than natural gas or crude oil, and it also differs based on where it comes from. Coal coming out of China has a different carbon composition than West Virginia coal.”

In this new study, the researchers used new provincial-level fossil fuel data and different carbon coefficients that are more representative of Chinese coal. China is also the world’s largest cement producer, and the new study reevaluated China’s releases of carbon dioxide from cement production as well. The team’s revised estimate found that China’s fossil-fuel and cement emissions are approximately 10 to 14% lower than other published inventories including CDIAC’s published estimates. Boden, Andres and Marland helped verify the team’s calculations based on their years of carbon accounting experience.

Although the corrected estimate does not change China’s status as the world’s largest emitter, it will benefit future efforts to project future climates.

“Differences on an order of 15% become important at global and regional carbon cycle scales,” Boden said. “For a country that’s emitting something on the order of two gigatons of carbon per year and with growing energy demands and large reserves of coal, it’s important to quantify China’s fossil-fuel emissions well.”

Source: Oak Ridge National Laboratory

Google Tests Six-Foot Humanoid Robot with Walk in Woods

Boston Dynamics, a robotics company owned by Google, posted footage of a prototype of their robot, named Atlas, taking a walk through the woods.

Atlas is designed, “to negotiate outdoor, rough terrain in a bipedal manner, while being able to climb using hands and feet as a human would,” writes The Guardian.

Marc Raibert, the founder of Boston Dynamics, provided an update on Atlas’s development to an audience at the 11th annual Fab Lab Conference and Symposium in Boston earlier this month.

He explained his team wanted to see how Atlas would perform in a wooded area because it was an unpredictable environment compared to the company’s laboratory.

Watch below.








Source:rdmag.com

X-ray duo’s research helps launch human trial for treatment of arsenic poisoning

Graham George and Ingrid Pickering, a husband and wife x-ray research team, have worked for decades to understand how contaminants in water and soil are taken up by the body and affect human health. Much of that research has taken place at the Stanford Synchrotron Radiation Lightsource (SSRL), a DOE Office of Science User Facility at SLAC National Accelerator Laboratory, where both are former staff scientists.

Now George and Pickering are co-leading a new study in Bangladesh that is testing whether giving people selenium supplements can protect them from arsenic poisoning caused by naturally contaminated drinking water, which affects more than 100 million people worldwide and can lead to cancer, liver disease and other severe health problems.

The clinical trial, which runs through July 2016, is paid for by the Canadian federal government and is sponsored by the Univ. of Saskatchewan, where Pickering and George have been professors since 2003.

Fighting poison with poison?
The idea for the treatment dates back to the 1930s, when a scientist discovered that rats fed wheat containing enough selenium to kill them could actually survive if they were also given arsenic-contaminated water.

Decades later, Jürgen Gailer, a scientist at the Univ. of Calgary in Canada who was conducting related research on this biological oddity, asked Pickering and George if they could use x-ray techniques to find out how combining these two toxins could seemingly cancel out their dangerous effects in mammals.

“We discovered the molecule responsible for this effect,” George said.

In a series of x-ray experiments that began over a decade ago at SSRL, George and Pickering identified a compound that forms in rabbits injected with both arsenic and selenium. When the rabbits excreted this compound it apparently removed the toxins.

The study, published in 2000, also concluded that people exposed to arsenic-contaminated water might get some protection by increasing their selenium intake, and it offered possible clues to why arsenic poisoning can be carcinogenic.

In the current trial in Bangladesh, one group of men is receiving sodium selenite, a compound that could potentially help to cleanse arsenic from their systems, and another group of men is receiving a placebo. This trial provides stricter controls on how the drugs are administered than a previous trial that was not successful.

Brain diseases, using plants for cleanup among latest projects
“Our focus has been on understanding the roles of metals in biology,” George said, as many proteins that carry out important functions in biology contain metallic elements. “We want to understand the detailed structure of metals in proteins’ active sites, and see how they’re localized in tissues.”

In addition to their ongoing arsenic and selenium work, the couple also are studying how plants can potentially be used to take contaminants out of the soil that are potentially hazardous to human health.

“Wouldn’t it be great if we could plant a crop of plants that can harvest contaminants into the roots and take them away?” Pickering said.

Another thread of their research uses x-ray experiments to explore the roles metal ions, and in particular copper ions, play in diseases related to misfolded proteins, such as Alzheimer’s and prion diseases—mad cow disease is one example.

George, who first visited SSRL in 1983, is a pioneer in biological studies using x-ray absorption spectroscopy to explore the atomic structure and arrangement of electrons in samples. This technique is also applicable to other fields, like chemistry and materials science. Pickering has focused her research on metals in the environment and how they impact biology and human health. She leads a synchrotron training program at her university for graduate students and postdoctoral researchers pursuing health-related research.

“We end up on each other’s papers a lot,” George says, because of natural overlaps in their research.

A long history at SSRL
Both originally from the United Kingdom, the couple met in New Jersey while working as researchers at Exxon and have been married for 23 years. They worked as staff scientists at SLAC’s SSRL from 1992 to 2003, and still come to SLAC to conduct experiments at SSRL.

During their recent six-month research sabbatical at SSRL, they conducted several x-ray experiments related to their biological research.

“We’ve been doing something we haven’t done in a long time, which is work on an x-ray beamline together,” said George, as work and family schedules have complicated their experimental time.

They also worked on software development to update an x-ray data analysis tool that George created decades ago, called EXAFSPAK, that is in use at synchrotrons around the globe. George said his brother, Martin, and Allyson Aranda, both SSRL scientific programmers, are also working on this ongoing update, which will add new features and make the software easier to use.

Future x-ray work
Graham George said he is excited about the new research possibilities using x-ray lasers like SLAC’s Linac Coherent Light Source, which has x-ray pulses a billion times brighter than synchrotron light. “LCLS is going to change everything for many people in science. It makes possible the ‘wow’ kind of science,” he said, adding that synchrotrons like SSRL will continue to be the workhorses in x-ray research.

The couple said they will continue to be drawn to SSRL for their own work.

“It’s a ‘can-do’ place. That translates to a really great user experience,” Pickering said. “People here are really keen to make sure your experiment is successful. That really does count for a lot.”

George added, “It doesn’t just have to do with the quality of the x-ray beams. It also has to do with good ideas and a good fundamental approach, and the systematic, careful nature of the people who work here.”


Source: SLAC National Accelerator Laboratory

Paper-based Tests for Infectious Diseases

In Kimberley Hamad-Schifferli’s hand, the device looks like a white iPod Mini, small enough to fit in a pants pocket. However, this device is actually a paper-based, rapid diagnostic test capable of finding the presence of infectious diseases, including Ebola, dengue and yellow fever.

“(We) took advantage of the fact that nanoparticles have different colors if you make them different sizes,” said Hamad-Schifferli, of the Massachusetts Institute of Technology (MIT), who presented the device at the 250th National Meeting & Exposition of the American Chemical Society (ACS). “If you put nanoparticles on the antibodies that are inside the test, it gives rise to a different color on the test line.”

According to the Centers for Disease Control and Prevention, the 2014 Ebola outbreak in West Africa killed nearly 11,300 people in Guinea, Sierra Leone and Liberia. Total suspected cases numbered close to 28,000.

“Our main goal is to get this into the hands of as many people as possible,” Hamad-Schifferli said.

She emphasized the test wasn’t designed as a replacement for PCR (polymerase chain reaction) and ELISA (enzyme-linked immunosorbent assay) tests, which are more accurate, but require laboratory settings. Rather, the new test is meant as a first screening for areas without running water or electricity.

According to ACS, PCR and ELISA “are bioassays that detect pathogens directly or indirectly, respectively.”

The test uses silver nanoparticles. Slight changes in size elicit different colors. Red was assigned to Ebola, green to dengue fever and orange to yellow fever. The colored nanoparticles are attached to antibodies that bind to a biomarker of interest. According to Hamad-Schifferli, the blood sample is introduced to a “cotton weave pad,” and wicks through the device as results develop. The results are read from a nitrocellulose membrane, the paper part of the device.

She reported the sensitivity and specificity of the test as 97% accurate. The test takes 10 min to complete.

At $5 per strip, the total test costs $20, but Hamad-Schifferli said mass production could reduce the cost. Currently, the research team is consulting with companies about making the product commercially available.

While the test performs well in the lab setting, the team, comprised of people from MIT, Harvard Medical School and the U.S. Food and Drug Administration, found problems with humidity and temperatures of 36 C. By using foil packs as a sealing, the test was stable for three months in the aforementioned environment. Once opened, it must be used immediately, Hamad-Schifferli said.

Tests have been deployed to clinical settings in Colombia, Honduras and Africa. Hamad-Schifferli said it would be a few months before her team receives feedback regarding the test’s performance in the field.

Source:http://www.rdmag.com/articles/2015/08/paper-based-tests-infectious-diseases

Medical, biofuel advances possible with new gene regulation tool

Recent work by Los Alamos National Laboratory experimental and theoretical biologists describes a new method of controlling gene expression. The key is a tunable switch made from a small non-coding RNA molecule that could have value for medical and even biofuel production purposes.

“Living cells have multiple mechanisms to control and regulate processes—many of which involve regulating the expression of genes,” said lead project scientist Clifford Unkefer of the Laboratory’s Bioscience Div. “Scientists have investigated ways of synthetically altering gene expression for alternative purposes, such as biosynthesis of therapeutics or chemicals. Much of this work has focused on regulating translation of genes. Now we have a way to do this, using a riboregulator.”

Synthetic biology researchers have been attempting to engineer bacteria capable of carrying out a range of important medical and industrial functions, from manufacturing pharmaceuticals to detoxifying pollutants and increasing production of biofuels.

“Cells rely on a complex network of gene switches,” said coauthor Karissa Sanbonmatsu. “Early efforts in synthetic biology presumed these switches were akin to turning a light bulb on or off. We have produced switches that more closely resemble continuous dimmers, carefully regulating gene expression with exquisite control,” she said.

Noted Scott Hennelly, another research team member, “Because these riboregulators can be used to tune gene expression and can be targeted specifically to independently regulate all of the genes encoding a metabolic pathway, they give the synthetic biologist the tools necessary to optimize flux in an engineered metabolic pathway and will find wide application in synthetic biology.”

The team’s work describes riboregulators that are made up of made up of a cis-repressor (crRNA) and a trans-activator RNAs (taRNA). The crRNA naturally folds to a structure that sequesters the ribosomal binding sequence, preventing translation of the downstream gene; thus blocking expression of the gene.

The taRNA is transcribed independently and the binding and subsequent structural transition between these two regulatory RNA elements dictates whether or not the transcribed mRNA will be translated into the protein product. In this project, the team demonstrated a cis-repressor that completely shut off translation of antibiotic-resistance reporters and the trans-activator that restores translation.

“They demonstrated that the level of translation can be tuned based on subtle changes in the primary sequence regulatory region of the taRNA; thus it is possible to achieve translational control of gene expression over a wide dynamic range,” said Hennelly.

Finally they created a modular system that includes a targeting sequence with the capacity to target specific genes independently giving these riboregulators the ability regulate multiple genes independently.


Source: Los Alamos National Laboratory

Engineers improving safety, reliability of batteries

The next big step forward in the quest for sustainable, more efficient energy is tantalizingly within reach thanks to research being led by Univ. of Tennessee (UT)’s Joshua Sangoro.

Sangoro, an assistant professor of chemical and biomolecular engineering, heads a group devoted to the study of soft materials—substances that can be manipulated while at room temperature, including liquids, polymers and foams.

While such materials have obvious use in fields like medicine or cosmetics, it’s their potential to reshape our use of energy that has the team’s focus.

“By changing the design of batteries and the substances used in them we can improve safety, performance, and reliability,” said Sangoro. “If you think about everything we use that needs power, we can affect practically everything in a big, big way.”

In the simplest terms, batteries rely on electrolytes within them to carry their charge from one electrode to another and in the process provide electric energy to the device they are powering. The most commonly used electrolytes are based on lithium salts combined with organic additives.

While lithium-ion batteries are becoming more efficient, they also produce great amounts of heat, which can trigger unwanted chemical reactions within the batteries. These reactions yield toxic and highly flammable substances such as hydrofluoric acid gas.

That resulting stress from such gases has led to fires and damaged cell phones, laptops and other electrical devices and was even thought to be the cause of some high-profile fires on airliners.

Sangoro’s team is developing a new kind of electrolyte that cuts down on many of those problems.

“We are developing ionic liquid systems to take the place of traditional electrolytes in batteries,” said Sangoro. “Not only are they nonflammable, but they are also much more stable in wide temperature ranges, and they have very low vapor pressure.

“They are more reliable and safer—without sacrificing the power requirements of the batteries.”

The other big advantage of the breakthrough is its adaptability.

By molding the substances into ultrathin films, the team has found a way to make power sources with more flexible structures.

Doing so increases the opportunity for their use not just in portable devices but also in solar cells, transistors, or anything that needs a portable power source.

“Based on the ionic liquids we now know, we calculate that there are ten quintillion possible combinations that could be used,” said Sangoro. “We haven’t even scratched the surface yet.”


Source: The Univ. of Tennessee, Knoxville