Geobiologist Honored by National Academy of Sciences

Dianne Newman, professor of biology and geobiology at Caltech and an investigator with the Howard Hughes Medical Institute, has been awarded the National Academy of Sciences (NAS) Award in Molecular Biology for her "discovery of microbial mechanisms underlying geologic processes." The award citation recognizes her for "launching the field of molecular geomicrobiology" and fostering greater awareness of the important roles microorganisms have played and continue to play in how Earth evolved.

"Trust me, no one was more shocked than I was by this news," says Newman. "It really honors the many the exceptional people who have come through my lab over the years, as well as the geobiology field more broadly. Geobiology is a venerable old field, which offers many fascinating and important problems that would benefit from the attention of individuals trained in mechanistic research. Hopefully this award will encourage more young people from molecular and cellular biology to enter the field."

Newman's research focuses on the relationship between microorganisms and geologic processes. She has demonstrated that some bacteria in iron-rich environments, such soils and sediments, can utilize extracellular iron as a dump site for excess electrons by generating extracellular electron shuttles, including a class of metabolites formerly considered to be redox-active antibiotics. Newman has also made contributions to our understanding of other microbial metabolic processes of geological significance, including how microbes respire using arsenate instead of oxygen, and how they perform photosynthesis using iron rather than water. In addition, she and her coworkers have studied the mechanisms by which certain microbes make stromatolites and magnetosomes, two types of structures that leave biosignatures in ancient rocks. Perhaps most importantly, her team has demonstrated the power of applying genetic analysis to diverse organisms from iron-rich environments, paving the way for others to do the same.

Newman is now hoping to bring tools commonly used in geochemistry to facilitate environmentally-informed studies of pathogens in chronic infections. For example, in collaboration with Caltech professor of geobiology Alex Sessions and researchers at Children's Hospital Los Angeles, Newman's group has characterized the composition and growth rate of pathogens in mucus collecting in the lungs of individuals with cystic fibrosis. Using this information, her lab is designing new experiments to reveal the survival mechanisms utilized by microorganisms—such as Pseudomonas aeruginosa, an opportunistic bacterium that colonizes the lungs of these patients—in this environment.

The NAS Award in Molecular Biology was first given in 1962. It is presented with a medal and a $25,000 prize. Newman will receive the award on May 1, 2016, during the National Academy of Sciences' annual meeting in Washington, D.C.

Previous recipients of the award include David Baltimore, Caltech President Emeritus and the Robert Andrews Millikan Professor of Biology.

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Dianne Newman has been awarded the National Academy of Sciences Award in Molecular Biology.

Delivering Genes Across the Blood-Brain Barrier

Caltech biologists have modified a harmless virus in such a way that it can successfully enter the adult mouse brain through the bloodstream and deliver genes to cells of the nervous system. The virus could help researchers map the intricacies of the brain and holds promise for the delivery of novel therapeutics to address diseases such as Alzheimer's and Huntington's. In addition, the screening approach the researchers developed to identify the virus could be used to make additional vectors capable of targeting cells in other organs.

"By figuring out a way to get genes across the blood-brain barrier, we are able to deliver them throughout the adult brain with high efficiency," says Ben Deverman, a senior research scientist at Caltech and lead author of a paper describing the work in the February 1 online publication of the journal Nature Biotechnology.

The blood-brain barrier allows the body to keep pathogens and potentially harmful chemicals circulating in the blood from entering the brain and spinal cord. The semi-permeable blockade, composed of tightly packed cells, is crucial for maintaining a controlled environment to allow the central nervous system to function properly. However, the barrier also makes it nearly impossible for many drugs and other molecules to be delivered to the brain via the bloodstream.

To sneak genes past the blood-brain barrier, the Caltech researchers used a new variant of a small, harmless virus called an adeno-associated virus (AAV). Over the past two decades, researchers have used various AAVs as vehicles to transport specific genes into the nuclei of cells; once there, the genes can be expressed, or translated, from DNA into proteins. In some applications, the AAVs carry functional copies of genes to replace mutated forms present in individuals with genetic diseases. In other applications, they are used to deliver genes that provide instructions for generating molecules such as antibodies or fluorescent proteins that help researchers study, identify, and track certain cells.

Largely because of the blood-brain barrier problem, scientists have had only limited success delivering AAVs and their genetic cargo to the central nervous system. In general, they have relied on surgical injections, which deliver high concentrations of the virus at the injection site but little to the outlying areas. Such injections are also quite invasive. "One has to drill a hole through skull, then pierce tissue with a needle to the injection site," explains Viviana Gradinaru (BS '05), assistant professor of biology and biological engineering at Caltech and senior author on the paper. "The deeper the injection, the higher the risk of hemorrhage. With systemic injection, using the bloodstream, none of that damage happens, and the delivery is more uniform."

In addition, Gradinaru notes, "many disorders are not tightly localized. Neurodegenerative disorders like Huntington's disease affect very large brain areas. Also, many complex behaviors are mediated by distributed interacting networks. Our ability to target those networks is key in terms of our efforts to understand what those pathways are doing and how to improve them when they are not working well."

In 2009, a group led by Brian Kaspar of Ohio State University published a paper, also in Nature Biotechnology, showing that an AAV strain called AAV9 injected into the bloodstream could make its way into the brain—but it was only efficient when used in neonatal, or infant, mice.

"The big challenge was how do we achieve the same efficiency in an adult," says Gradinaru.

Although one might like to design an AAV that is up to the task, the number of variables that dictate the behavior of any given virus, as well as the intricacies of the brain and its barrier, make that extremely challenging. Instead, the researchers developed a high-throughput selection assay, CREATE (Cre REcombinase-based AAV Targeted Evolution), that allowed them to test millions of viruses in vivo simultaneously and to identify those that were best at entering the brain and delivering genes to a specific class of brain cells known as astrocytes.

They started with the AAV9 virus and modified a gene fragment that codes for a small loop on the surface of the capsid—the protein shell of the virus that envelops all of the virus' genetic material. Using a common amplification technique, known as polymerase chain reaction (PCR), they created millions of viral variants. Each variant carried within it the genetic instructions to produce more capsids like itself.

Then they used their novel selection process to determine which variants most effectively delivered genes to astrocytes in the brain. Importantly, the new process relies on strategically positioning the gene encoding the capsid variants on the DNA strand between two short sequences of DNA, known as lox sites. These sites are recognized by an enzyme called Cre recombinase, which binds to them and inverts the genetic sequence between them. By injecting the modified viruses into transgenic mice that only express Cre recombinase in astrocytes, the researchers knew that any sequences flagged by the lox site inversion had successfully transferred their genetic cargo to the target cell type—here, astrocytes.

After one week, the researchers isolated DNA from brain and spinal cord tissue, and amplified the flagged sequences, thereby recovering only the variants that had entered astrocytes.

Next, they took those sequences and inserted them back into the modified viral genome to create a new library that could be injected into the same type of transgenic mice. After only two such rounds of injection and amplification, a handful of variants emerged as those that were best at crossing the blood-brain barrier and entering astrocytes.

"We went from millions of viruses to a handful of testable, potentially useful hits that we could go through systematically and see which ones emerged with desirable properties," says Gradinaru.

Through this selection process, the researchers identified a variant dubbed AAV-PHP.B as a top performer. They gave the virus its acronym in honor of the late Caltech biologist Paul H. Patterson because Deverman began this work in Patterson's group. "Paul had a commitment to understanding brain disorders, and he saw the value in pushing tool development," says Gradinaru, who also worked in Patterson's lab as an undergraduate student.

To test AAV-PHP.B, the researchers used it to deliver a gene that codes for a protein that glows green, making it easy to visualize which cells were expressing it. They injected the AAV-PHP.B or AAV9 (as a control) into different adult mice and after three weeks used the amount of green fluorescence to assess the efficacy with which the viruses entered the brain, the spinal cord, and the retina.

"We could see that AAV-PHP.B was expressed throughout the adult central nervous system with high efficiency in most cell types," says Gradinaru. Indeed, compared to AAV9, AAV-PHP.B delivers genes to the brain and spinal cord at least 40 times more efficiently.  

"What provides most of AAV-PHP.B's benefit is its increased ability to get through the vasculature into the brain," says Deverman. "Once there, many AAVs, including AAV9 are quite good at delivering genes to neurons and glia."

Gradinaru notes that since AAV-PHP.B is delivered through the bloodstream, it reaches other parts of the body. "Although in this study we were focused on the brain, we were also able to use whole-body tissue clearing to look at its biodistribution throughout the body," she says.

Whole-body tissue clearing by PARS CLARITY, a technique developed previously in the Gradinaru lab to make normally opaque mammalian tissues transparent, allows organs to be examined without the laborious task of making thin slide-mounted sections. Thus, tissue clearing allows researchers to more quickly screen the viral vectors for those that best target the cells and organs of interest.

"In this case, the priority was to express the gene in the brain, but we can see by using whole-body clearing that you can actually have expression in many other organs and even in the peripheral nerves," explains Gradinaru. "By making tissues transparent and looking through them, we can obtain more information about these viruses and identify targets that we might overlook otherwise."

The biologists conducted follow-up studies up to a year after the initial injections and found that the protein continued to be expressed efficiently. Such long-term expression is important for gene therapy studies in humans. 

In collaboration with colleagues from Stanford University, Deverman and Gradinaru also showed that AAV-PHP.B is better than AAV9 at delivering genes to human neurons and glia.

The researchers hope to begin testing AAV-PHP.B's ability to deliver potentially therapeutic genes in disease models. They are also working to further evolve the virus to make even better performing variants and to produce variants that target certain cell types with more specificity.

Deverman says that the CREATE system could indeed be applied to develop AAVs capable of delivering genes specifically to many different cell types. "There are hundreds of different Cre transgenic lines available," he says. "Researchers have put Cre recombinase under the control of gene regulatory elements so that it is only made in certain cell types. That means that regardless of whether your objective is to target liver cells or a particular type of neuron, you can almost always find a mouse that has Cre recombinase expressed in those cells."

"The CREATE system gave us a good hit early on, but we are excited about the future potential of using this approach to generate viruses that have very good cell-type specificity in different organisms, especially the less genetically tractable ones," says Gradinaru. "This is just the first step. We can take these tools and concepts in many exciting directions to further enhance this work, and we—with the Beckman Institute and collaborators—are ready to pursue those possibilities." 

The Beckman Institute at Caltech recently opened a resource center called CLOVER (CLARITY, Optogenetics, and Vector Engineering Research Center) to support such research efforts involving tissue clearing and imaging, optogenetic studies, and custom gene-delivery vehicle development. Deverman is the center's director, and Gradinaru is the principal investigator.

Additional Caltech authors on the paper, "Cre-dependent selection yields AAV variants for widespread gene transfer to the adult brain," are Sripriya Ravindra Kumar, Ken Y. Chan, Abhik Banerjee, Wei-Li Wu, and Bin Yang, as well as former Caltech students Piers L. Pravdo and Bryan P. Simpson. Nina Huber and Sergiu P. Pasca of Stanford University School of Medicine are also coauthors. The work was supported by funding from the Hereditary Disease Foundation and the Caltech-City of Hope Biomedical Initiative, a National Institutes of Health (NIH) Director's New Innovator Award, the NIH's National Institute of Aging and National Institute of Mental Health, the Beckman Institute, and the Gordon and Betty Moore Foundation.

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Delivering Genes Across the Blood-Brain Barrier
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Caltech biologists have developed a vector capable of noninvasive delivery of genetic cargo throughout the adult central nervous system.

Rosens Recharge Support for Bioengineering

Caltech board chair emeritus and longtime Compaq chairman Benjamin M. (Ben) Rosen (BS '54) and his wife, Donna, have made a bequest commitment to advance scientific exploration at the intersection of biology and engineering. It is anticipated that the couple's latest gift may double the endowment for the Donna and Benjamin M. Rosen Bioengineering Center.

Established in 2008 with $18 million from the Benjamin M. Rosen Family Foundation of New York, the Rosen Center has become a hub for research and educational initiatives that bring together applied physics, chemical engineering, synthetic biology, computer science, and more.

"Just as we had the digital revolution in the last century, we are having a biological sciences revolution in this century," Ben Rosen says. "And Caltech is the place to be."

Read more on the Caltech giving site.

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Caltech board chair emeritus Ben Rosen (BS ’54) and his wife Donna have made a commitment to scientific exploration at the intersection of biology and engineering.
Friday, January 29, 2016
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A Healthy Start

Science and medicine, it would seem, have always gone hand in hand. But for centuries, they were actually two very disparate fields. Identifying a need for "investigators who are well trained in both basic science and clinical research," the National Institutes of Health (NIH) created the Medical Scientist Training Program (MSTP) in 1964 to help streamline completion of dual medical and doctoral degrees. The purpose of developing this highly competitive MD/PhD program was to support "the training of students with outstanding credentials and potential who are motivated to undertake careers in biomedical research and academic medicine."

Recognizing Caltech's strength in the biological and chemical sciences, UCLA—which first established an MSTP in 1983—formed an affiliation with the Institute in 1997 to offer an average of two students the opportunity to perform graduate research at the partner school through the MSTP; PhD thesis work is done at Caltech for UCLA medical students, and when completed they return to UCLA to finish their MD studies.

The vast majority of alumni who have completed their postgraduate training are actively involved in biomedical research as physician-scientists at outstanding research institutions across the country. Although the MSTP represented the first formal affiliation between UCLA and Caltech, the success of the combined UCLA-Caltech MSTP spearheaded and served as a model for several other joint efforts that benefit from the complementary strengths of the two institutions, including the Specialized Training and Advanced Research (STAR) fellowship program for physician-scientists, and the Institute for Molecular Medicine.

A joint program with the University of Southern California soon followed. In 1998, the Kenneth T. and Eileen L. Norris Foundation awarded Caltech funding to support a joint MD/PhD program with the Keck School of Medicine of USC.

The grant established the Norris Foundation MD/PhD Scholars Fund, which supports Caltech PhD candidates from Keck. Administered by Caltech in cooperation with USC, the program accepts two students each year. As with the UCLA program, students spend their first two years in medical school, taking preclinical science courses, with summers spent at Caltech gaining exposure to the academic research environment. They then come to Caltech, spending three to five years on their PhDs before returning to their medical school for the final two clinical years.

The late Caltech biologist Paul Patterson, who passed away in 2014, was instrumental in developing the joint degree program. He believed that Caltech graduate students should also have an opportunity to explore their work in a clinical setting.

"Paul showed creativity both in curriculum development, in student mentoring, and in bringing the Caltech faculty together to support a program, which was in collaboration with another major institution," says Richard Bergman, director of the Cedars-Sinai Diabetes and Obesity Research Institute, who helped Patterson form the initial collaboration with USC. "His contributions in this regard educated several generations of students who, today, continue to make important contributions to medical science. This was a great legacy of Professor Patterson."

Additional funding for students in the MD/PhD programs has come from a provost-directed endowed fund called the W. R. Hearst Endowed Scholarship for MD/PhD Students; from the Lee-Ramo Life Sciences Fund; and through lab support for medical research from the W. M. Keck Foundation Fund for Discovery in Basic Medical Research. The Division of Biology and Biological Engineering also provides support to students and scholars who are headed for careers in medicine through an endowed fund from the Walter and Sylvia Treadway Foundation.

Since the start of the two MD/PhD programs, 64 students have been accepted to work toward dual degrees, and 40 have received PhDs from Caltech.

This story was reprinted from the Winter 2015 E&S magazine. See the full issue online.

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Explore the origins of Caltech's joint MD/PhD programs, which help students develop expertise in both basic science and clinical research.
Saturday, January 30, 2016
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Stem Cells, Gene Regulatory Networks and the Evolution of Vertebrates: A symposium recognizing the contributions of Marianne Bronner to our understanding of the neural crest and cranial placodes

Friday, January 29, 2016
Beckman Institute Auditorium – Beckman Institute

Stem Cells, Gene Regulatory Networks and the Evolution of Vertebrates: A symposium recognizing the contributions of Marianne Bronner to our understanding of the neural crest and cranial placodes

Identification Tags Define Neural Circuits

The human brain is composed of complex circuits of neurons, cells that are specialized to transmit information via electrochemical signals. Like the circuits in a computer, these neuronal circuits must be connected in particular ways to function properly. But with billions of neurons in a single human brain, how does a neuron make the right connections with the right cells?

Biologists have long searched for some kind of cellular "identification tags" that label which cells should form connections. Now, researchers from the laboratory of Caltech professor of biology Kai Zinn have identified molecules that act like identification tags on neurons in the fruit fly Drosophila. They discovered that proteins from two different molecular subfamilies, called Dpr and DIP proteins, bind together selectively. This binding can cause neurons that express Dpr proteins to form connections with neurons that express the corresponding DIP protein, playing an important role in directing the development of the neuromuscular and visual systems in growing Drosophila.

A paper detailing the findings is published in the December 17 issue of the journal Cell.

In 2013, a collaboration between Christopher Garcia's structural biology group at Stanford and the Zinn group at Caltech mapped the interactions between all 200 different Drosophila cell surface proteins. By separating the proteins from the cell and observing their interactions in a test tube, the group determined which proteins bind together. The group developed a complex model of interacting proteins they called the interactome. This work showed that a 21-member subfamily of "immunoglobulin superfamily" proteins, the Dprs, selectively bind to a 9-member subfamily called DIPs.

"Certain members of the Dprs and the DIPs match up and bind together—kind of like a lock and key—in a test tube," says Zinn. "We wanted to know if they would bind in vivo, in the Drosophila brain, and if that binding would then determine where synapses were formed."

A synapse is a junction where the wire-like axon of one neuron meets the branched dendrites of another. Information, in the form of chemical signals called neurotransmitters, is passed between neurons across these synapses. "We wanted to know if these interacting proteins on the surface of neuronal cells affected the way that the cells themselves interacted," says Robert Carrillo, a postdoctoral scholar in the Zinn group and co-first author on the new paper. "We showed that neural cells that expressed matching proteins often formed synapses with each other, and we theorized that the interaction between these molecules was driving the formation of synapses."

To test this theory, the Zinn group used the well-studied Drosophila visual system to determine the effects of these proteins on development. Neurons in the fly's eye send axons into layered structures in the visual part of the brain, which is known as the optic lobe. One of these structures, the medulla, is divided into ten layers, and each optic lobe neuron forms synapses within a specific subset of these layers. By removing certain DIP and Dpr proteins in the fly pupa, the researchers caused the axons to "overshoot" their target layers. Additionally, they observed developmental defects in the fly's neuromuscular system when removing the same proteins. Another paper in the same issue of Cell, from Larry Zipursky's group at UCLA, also found that expression of Dprs and DIPs correlates with the patterns of synaptic connectivity in the brain.

This finding helps to validate a theory proposed in the 1950s by the late Caltech professor and Nobel Laureate Roger Sperry. Experimenting mostly with fish and frog brains, Sperry discovered that he could manipulate or cut axons between neurons, and the cells would still re-form the right connections.

"Sperry hypothesized that individual neurons must carry some kind of identification tags, whose recognition is used to create the synaptic circuits of the brain," says Kaushiki Menon, a senior postdoctoral scholar in the Zinn group and a co-first author on the paper. "Our group has shown that the Drosophila Dpr and DIP proteins fit the definition of Sperry's proposed cellular identification tags."

Such tinkering with the brain's circuitry is possible because flies, unlike humans, have brains that are predominantly "hard-wired." "In mammals, the brain has a basic initial scaffold laid down by genetics, and then over time there is a lot of complicated experience-dependent rearrangement. Essentially, the brain can rewire itself through experience," Zinn says. "Fly brains can't do that."

While their findings are not immediately generalizable to mammals, Zinn and his group hope that they can provide a starting point to probe the structure of the human brain. "We hope that there might be protein networks that function similarly in humans, and these could be relevant to an understanding of how the scaffold of the human brain that exists at birth is assembled through genetics."

The paper is titled "Control of synaptic connectivity by a network of Drosophila IgSF cell surface proteins." In addition to Carrillo and Menon, structural biologist Engin Özkan at the University of Chicago is a  co-first author. The work was funded by the National Institutes of Health and the Howard Hughes Medical Institute.

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Identification Tags Define Neural Circuits
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Biologists have identified a network of proteins that guides neural synapse formation in Drosophila brains.

15 for 2015: The Year in Research News at Caltech

The year 2015 proved to be another groundbreaking year for research at Caltech. From seeing quantum motion, to reconfiguring jellyfish limbs, to measuring stellar magnetic fields, researchers continued to ask and answer the deepest scientific questions.

In case you missed any of them, here are 15 stories highlighting a few of the discoveries, methods, and technologies that came to life at Caltech in 2015.

 

 

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Here are 15 stories highlighting a few of the discoveries, methods, and technologies that came to life at Caltech in 2015.

15 for 2015: The Year in Research News at Caltech

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15 for 2015: The Year in Research News at Caltech
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Credit: K.Batygin/Caltech

New Research Suggests Solar System May Have Once Harbored Super-Earths

Thanks to recent surveys of exoplanets—planets in solar systems other than our own—we know that most planetary systems typically have one or more super-Earths (planets that are substantially more massive than Earth but less massive than Neptune) orbiting closer to their suns than Mercury does. In March, researchers showed that our own solar system may have once had these super-Earths, but they were destroyed by Jupiter's inward and outward migration through the solar system. This migration would have gravitationally flung small planetesimals through the solar system, setting off chains of collisions that would push any interior planets into the sun.
Credit: Lance Hayashida/Caltech and the Hoelz Laboratory/Caltech

Caltech Biochemists Shed Light on Cellular Mystery

The nuclear pore complex (NPC) is an intricate portal linking the cytoplasm of a cell to its nucleus. It is made up of many copies of about 34 different proteins. Around 2,000 NPCs are embedded in the nuclear envelope of a single human cell and each NPC shuttles hundreds of macromolecules of different shapes and sizes between the cytoplasm and nucleus. In February, Caltech biochemists determined the structure of a significant portion of the NPC called the outer rings; in August, the same group solved the structure of the pore's inner ring. Understanding the structure of the NPC could lead to new classes of cancer drugs as well as antiviral medicines.
Credit: iStockphoto

Research Suggests Brain's Melatonin May Trigger Sleep

For decades, supplemental melatonin has been sold over the counter as a sleep aid despite the absence of scientific evidence proving its effectiveness. Few studies have investigated melatonin produced naturally in the human body. This March, Caltech researchers studying zebrafish—animals that, like humans, are awake during the day and asleep at night—determined that the melatonin hormone does help the body fall asleep and stay asleep. Specifically, they found that zebrafish larvae that could not produce melatonin slept for only half as long as normal larvae.
Credit: Gregg Hallinan/Caltech

Advances in Radio Astronomy

In May, a new radio telescope array called the Owens Valley Long Wavelength Array (OV-LWA) saw its first light. Developed by a consortium led by Caltech, the OV-LWA has the ability to image simultaneously the entire sky at radio wavelengths with unmatched speed, helping astronomers to search for objects and phenomena that pulse, flicker, flare, or explode.

In July, Caltech researchers used both radio and optical telescopes to observe a brown dwarf located 20 light-years away and found that these so-called failed stars host powerful auroras near their magnetic poles.
Credit: Michael Abrams and Ty Basinger

Injured Jellyfish Seek to Regain Symmetry

Some kinds of animals can regrow lost limbs and body parts, but moon jellyfish have a different strategy. In June, Caltech researchers reported that the star-shaped eight-armed moon jellyfish rearranges itself when injured to maintain symmetry. It is hypothesized that the rearrangement helps to preserve the jellyfish's propulsion mechanism.
Credit: NASA/JPL-Caltech

Geologists Characterize Nepal Earthquake

In April, a magnitude 7.8 earthquake rocked Nepal. While the damage was extensive, it was not as severe as many geologists predicted. This year, a Caltech team of geologists used satellite radar imaging data and measurements from seismic instruments in Nepal to create models of fault rupture and ground movement. They found that the quake ruptured only a small fraction of the "locked" tectonic plate and that there is still the potential for the locked portion to produce a large earthquake.
Credit: Caltech/JPL

New Polymer Creates Safer Fuels

Plane crashes cause devastating damage, but this damage is often exacerbated by the highly explosive nature of jet fuel. This October, researchers at Caltech and JPL discovered a polymeric fuel additive that can reduce the intensity of postimpact explosions that occur during accidents and crashes. Preliminary results show that the additive can provide this benefit without adversely affecting fuel performance. The polymer works by inhibiting "misting"—the process that causes fuel to rapidly disperse and easily catch fire—under crash conditions.
Credit: Spencer Kellis/Caltech

Controlling a Robotic Arm with a Patient's Intentions

When you reach for a glass of water, you do not consciously think about moving your arm muscles or grasping with your fingers—you think about the goal of the movement. This May, by implanting neural prosthetic devices into the posterior parietal cortex (PCC)—the region of the brain that governs intentions for movement—rather than the motor cortex, which controls movement, Caltech researchers enabled a paralyzed patient to more smoothly and naturally control a prosthetic limb. In November, the researchers showed that there are individual neurons in the PPC that encode for entire hand shapes, such as those used for grasping or gesturing.

 

Caltech Scientists Develop Cool Process to Make Better Graphene

Graphene is an ultrastrong and conductive material made of a single layer of carbon atoms. While it is a promising material for scientific and engineering advances, manufacturing it on an industrially relevant scale has proven to be impractical, requiring temperatures of around 1,800 degrees Fahrenheit and long periods of time. A new technique invented at Caltech allows the speedy production of graphene—in just a few minutes—at room temperatures. The technique also produces graphene that is stronger, smoother, and more electrically conductive than normally produced synthetic graphene.
Credit: Rafael A. García (SAp CEA), Kyle Augustson (HAO), Jim Fuller (Caltech) & Gabriel Pérez (SMM, IAC), Photograph from AIA/SDO

Astronomers Peer Inside Stars, Finding Giant Magnets

Before this October, astronomers have only been able to study the magnetic fields of stars on the stellar surfaces. Now, using a technique called asteroseismology, scientists were able to probe the fusion-powered hearts of dozens of red giants (stars that are evolved versions of our sun) to calculate the magnetic field strengths inside those stars. They found that the internal magnetic fields of the red giants were as much as 10 million times stronger than Earth's magnetic field. Magnetic fields play a key role in the interior rotation rate of stars, which has a dramatic effect on how the stars evolve.
Credit: Chan Lei and Keith Schwab/Caltech

Seeing Quantum Motion

To the casual observer, an object at rest is just that—at rest, motionless. But on the subatomic scale, the object is most certainly in motion—quantum mechanical motion. Quantum motion, or noise, is ever-present in nature, and in August, Caltech researchers discovered how to observe and manipulate that motion in a small device. By creating what they called a "quantum squeezed state," they were able to periodically reduce the quantum fluctuations of the device. The ability to control quantum noise could one day be used to improve the precision of very sensitive measurements.
Credit: Ali Hajimiri/Caltech

New Camera Chip Provides Superfine 3-D Resolution

3-D printing can produce a wide array of objects in relatively little time, but first the printer needs to have a blueprint of what to print. The blueprints are provided by 3-D cameras, which scan objects and create models for the printer. Caltech researchers have now developed a 3-D camera that produces the highest depth-measurement accuracy of any similar device, allowing it to deliver replicas of an object to be 3-D printed within microns of similarity to the original object. In addition, the camera, known as a nanophotonic coherent imager, is inexpensive and small.
Credit: Image provided courtesy of Joint Center for Artificial Photosynthesis; artwork by Darius Siwek.

One Step Closer to Artificial Photosynthesis and 'Solar Fuels'

Plants are masters of photosynthesis—the process of turning carbon dioxide, sunlight, and water into oxygen and sugar. Inspired by this natural and energy-efficient process, Caltech researchers have created an "artificial leaf" that takes in CO2, sunlight, and water to produce hydrogen fuels. This solar-powered system, one researcher says, shatters all of the combined safety, performance, and stability records for artificial leaf technology by factors of 5 to 10 or more.
Credit: Santiago Lombeyda and Robin Betz

Potassium Salt Outperforms Precious Metals As a Catalyst

Rare precious metals have been the standard catalyst for the formation of carbon-silicon bonds, a process crucial to the synthesis of a host of products from new medicines to advanced materials. However, they are expensive, inefficient, and produce toxic waste byproducts. This February, Caltech researchers discovered a much more sustainable catalyst in the form of a simple potassium salt that is one of the most abundant metals on Earth and thousands of times less expensive than other commonly used catalysts. In addition, the potassium salt is much more effective at running challenging chemical reactions than state-of-the-art precious metal complexes.
Credit: Qi Zhao/National University of Singapore

Probing the Mysterious Perceptual World of Autism

The way in which people with autism spectrum disorder (ASD) perceive the world is unique. It has been a long-standing belief that people with ASD often miss facial cues, contributing to impaired social interaction. In a study published in October, Caltech researchers showed 700 images to 39 subjects and found that people with ASD pay closer attention to simple edges and patterns in images than to the faces of people. The study also found that subjects were strongly attracted to the center of images—regardless of what was placed there—and to differences in color and contrast rather than facial features. These findings may help doctors diagnose and more effectively treat the different forms of autism.
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The year 2015 proved to be another groundbreaking year for research at Caltech. From seeing quantum motion, to reconfiguring jellyfish limbs, to measuring stellar magnetic fields, researchers continued to ask and answer the deepest scientific questions.

In case you missed any of them, here are 15 stories highlighting a few of the discoveries, methods, and technologies that came to life at Caltech in 2015.

Written by Lori Dajose

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