Category: Physics Page 5 of 11

Ghost Hunters: Duke Physicists Track the Changeable Neutrino

On April 12, 2016

One kilometer below the surface of Mount Ikeno in Japan lies Super-Kamiokande, the largest neutrino detector of its kind in the world. This 12-story, cylindrical chamber holds 50,000 tons of water and is lined with over 11,000 tubes that spot the bursts of light emitted when high-energy neutrinos collide with matter.

Nearly 20 years ago, experiments at Super-K and elsewhere revealed that neutrinos can oscillate or change “flavor,” a discovery which proved that the ghostly particles have mass and upended their role in the Standard Model of physics. Since then, Duke physicists Kate Scholberg and Chris Walter have used the massive detector to further explore the nature of these neutrino oscillations, seeking to pin down how and when they change their flavors and what this might mean for our understanding of physics.

Within the massive Super-Kamiokande neutrino experiment in Japan, researchers travel by boat to check individual photomultiplier tubes that detect bursts of light created when neutrinos interact with water. Credit: Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo.

On Wednesday, Scholberg and Walter, along with Duke neutrino physicist Phillip S. Barbeau, will tell the story of neutrino oscillations in a talk titled, “Hunting Ghosts, How a 50,000-ton underground detector revealed the changeable nature of the neutrino and altered our view of the Universe,” presented as part of the Natural sciences in the 21st century colloquium.

In preparation for the talk, Scholberg spoke with colloquium organizer Rotem Ben-Shachar about the nature of neutrinos, what makes them so hard to catch, and what they have teach us about the origins of matter in our universe.

What is a neutrino?

Neutrinos, sometimes known as “ghost particles,” are among the known “elementary” particles: unlike atoms, they are not made up of anything smaller. Neutrinos are special because they are neutral, meaning they have no electric charge, and they interact extremely weakly with matter. They also have very tiny masses: a neutrino has no more than about 1/500,000 the mass of an electron. Because of their tiny masses, neutrinos travel at speeds close to the speed of light. Neutrinos come in three “flavors”: electron, muon and tau.

Why are neutrinos so hard to catch?

Neutrinos only interact only via the weak force — this is one of the four known forces, the others being gravity, electromagnetism, and the strong force which holds atomic nuclei together. As you might guess from the name, the weak force is really feeble, and that means that neutrinos hardly ever interact with matter at all. Mostly they just pass right through things without leaving any trace. Once in a while, they do interact, leaving a charged particle that you can detect. In order to “catch” a neutrino — to detect the interaction — you need either a huge number of neutrinos, or an enormous detector, or preferably both. For example, Super-Kamiokande is gigantic, but we see only about ten high-energy neutrinos per day in the detector. On the surface of the Earth, cosmic radiation can easily swamp a signal this slight, so neutrino detectors are often built underground where they are shielded from cosmic radiation.

When we can catch a neutrino, what do we learn from it?

Duke scientists suspended inside the Super-K detector.

Particle physicists like us try to understand the basic nature of matter and energy: our goal is to learn what the universe is made of, and how its constituents interact with one another. We’re also interested in cosmology — the history and evolution of the entire universe. It’s essential to understand the fundamental physics in order to understand what happened after the Big Bang, and why the universe looks as it does today. For instance, nobody understands why the universe is made primarily of matter and not antimatter, which has properties very much like matter, but with opposite charge. The study of neutrinos can give insight into many questions like this one.

What specifically we learn with a neutrino detector depends on the source of neutrino, the type of neutrino, and how far the neutrinos travel. For instance, at Super-K we can detect neutrinos that come from collisions of cosmic rays, high energy particles from outer space, with the upper atmosphere. These neutrinos travel through the Earth: some of them go a short distance, and some of them travel all the way from the other side of the Earth. What we observe is that neutrinos change from one flavor to another as they travel — it turns out that this can only happen if neutrinos have mass.

The 2015 Nobel prize in physics was awarded for discovery of neutrino oscillations by the Super-Kamiokande and Sudbury Neutrino Observatory experiments. Why was this discovery so important?

The discovery that neutrinos oscillate as they travel — they change their flavor — told us that neutrinos have non-zero mass. This is a really fundamental piece of information. It completely changes the role neutrinos play in the Standard Model of particle physics, and in fact we still don’t know exactly how to fit neutrinos with mass into the picture; how to do this depends on whether neutrinos and antineutrinos are really the same particles or not.

Neutrino mass also matters for cosmology. Since neutrinos have mass, we know they make up some of the unknown “dark matter” of the Universe, but we also now know that neutrinos can only make up a small fraction of the dark matter. Exactly *how* the neutrinos oscillate also matters, as this depends on fundamental parameters of nature.

A 3-D display of a candidate electron-neutrino event in the Super-Kamiokande detector. Each of the colored dots represents a detector that was hit by the light created when the electron neutrino interacted with the detector.

How does your research build on the discovery of neutrino oscillations?

The discovery of oscillations in atmospheric and solar neutrinos by Super-K and SNO has now been confirmed by multiple other experiments, and we’ve made tremendous progress over the past 20 years in refining our understanding of neutrino oscillations. An experiment we are involved in at Duke, T2K (“Tokai to Kamioka”), sends a beam of high-energy neutrinos from an accelerator a distance of 300 km to Super-K. This experiment has discovered new oscillation properties of neutrinos and will continue to take data over the next several years.

But there are still big questions out there about neutrinos — we have three neutrinos, but we don’t know if we have two heavier ones and one light one, or two light ones and a heavy one, which matters for the big picture. We don’t know if oscillations of neutrinos and antineutrinos happen differently. We don’t know if neutrinos and antineutrinos are really the same particles. The answers to these questions may help us understand the origin of matter. A next-generation beam experiment, DUNE, will send a beam of neutrinos 1300 kilometers from Fermilab to South Dakota and may answer some of these questions — and if we are lucky, we’ll also catch a burst of neutrinos from a supernova.

The Natural sciences in the 21st century colloquium will be held Wednesday, April 13 at 4:30 PM in Duke’s Gross Hall, room 107.

Kara J. Manke, PhD

Post by Kara Manke

Finding other Earths: the Chemistry of Star and Planet Formation

By Anika Radiya-Dixit

On March 31, 2016

In Chemistry, Computers/Technology, Physics

In the last two decades, humanity has discovered thousands of extrasolar planetary systems. Recent studies of star- and planet-formation have shown that chemistry plays a pivotal role in both shaping these systems and delivering water and organic species to the surfaces of nascent terrestrial planets. Professor Geoffrey A. Blake in Chemistry at the California Institute of Technology talked to Duke faculty and students over late-afternoon pizza in the Physics building on the role of chemistry in star and planet formation and finding other Earth-like planets.

The Milky Way rising above the Pacific Ocean and McKay Cove off the central California coast.

In the late 18^th century, French scholar Pierre-Simon Laplace analyzed what our solar system could tell us about the formation & evolution of planetary systems. Since then, scientists have used the combination our knowledge for small bodies like asteroids, large bodies such as planets, and studies of extrasolar planetary systems to figure out how solar systems and planets are formed.

The “Astronomer’s periodic table,” showing the relative contents of the various elements present in stars like the sun.

In 2015, Professor Blake and other researchers investigated more into ingredients in planets necessary for the development of life. Using the Earth and our solar system as the basis for their data, they explored the relative disposition of carbon and nitrogen in each stage of star and planet formation to learn more about core formation and atmospheric escape. Analyzing the carbon-silicon atomic ratio in planets and comets, Professor Blake discovered that rocky bodies in the solar system are generally carbon-poor. Since carbon is essential for our survival, however, Blake and his colleagues would like to determine the range of carbon content that terrestrial planets can have and still have active biosystem.

Analysis of C/Si ratios in extraterrestrial bodies revealed low carbon content in the formation of Earth-like planets.

With the Kepler mission, scientists have detected a variety of planetary objects in the universe. How many of these star-planet systems – based on measured distributions – have ‘solar system’ like outcomes? A “solar system” like planetary system has at least one Earth-like planet at approximately 1 astronomical unit (AU) from the star – where more ideal conditions for life can develop – and at least one ice giant or gas giant like Jupiter at 3-5 AU in order to keep away comets from the Earth-like planet. In our galaxy alone, there are around 100 billion stars and at least as many planets. For those stars similar to our sun, there exist over 4 million planetary systems similar to our solar system, with the closest Earth-like planet at least 20 light years away. With the rapid improvement of scientific knowledge and technology, Professor Blake estimates that we would be able to collect evidence within next 5-6 years of planets within 40-50 light years to determine if they have a habitable atmosphere.

Graph displaying the locations of Earth-like planets found at 0.01-1 AU from a star, and Jupiter-like planets at 0.01-50 AU from a star.

How does an Earth and a Jupiter form at their ideal distances from a star? Let’s take a closer look at how stars and planets are created – via the astrochemical cycle. Essentially, dense clouds of gas and dust become so opaque and cold that they collapse into a disk. The disk, rotating around a to-be star, begins to transport mass in toward the center and angular momentum outward. Then, approximately 1% of the star mass is left over from the process, which is enough to form planets. This is also why planets around stars are ubiquitous.

The Astrochemical Cycle: how solar systems are formed.

How are the planets formed? The dust grains unused by the star collide and grow, forming larger particles at specific distances from the star – called snowlines – where water vapor turns into ice and solidifies. These “dust bunnies” grow into planetesimals (~10-50 km diameter), such as asteroids and comets. If the force of gravity is large enough, the planetesimals increase further in size to form oligarchs (~0.1-10 times the mass of the Earth), that then become the large planets of the solar system.

Depiction of the snow line for planet formation.

In our solar system, a process called dynamic reorganization is thought to have occurred that restructured the order of our planets, putting Uranus before Neptune. This means that if other solar systems did not undergo such dynamic reorganization at an early point in formation of solar system, then other Earths may have lower organic and water content than our Earth. In that case, what constraints do we need to apply to determine if a water/organic delivery mechanism exists for exo-Earths? Although we do not currently have the scientific knowledge to answer this, with ALMA and the next generation of optical/IR telescopes, we will be able image the birth of solar systems directly and better understand how our universe came to be.

To the chemistry students at Duke, Professor Blake relayed an important message: learn chemistry fundamentals very carefully while in college. Over the next 40-50 years, your interests will change gears many times. Strong fundamentals, however, will serve you well, since you are now equipped to learn in many different areas and careers.

Professor Blake and the team of former and current Caltech researchers.

Learn more about the Blake research group or their work.

Anika_RD_hed100_2

By Anika Radiya-Dixit.

The Future of 3D Printing in Medicine

By Anika Radiya-Dixit

On March 23, 2016

In Art, Biology, Biomedical Engineering, Computers/Technology, Engineering, Medicine, Physics, Students

While 3D printers were once huge, expensive devices only available to the industrial elite, they have rapidly gained popularity over the last decade with everyday consumers. I enjoy printing a myriad of objects at the Duke Colab ranging from the Elder Wand to laptop stands.

One of the most important recent applications of 3D printing is in the medical industry. Customized implants and prosthetics, medical models and equipment, and synthetic skin are just a few of the prints that have begun to revolutionize health care.

3D printed prosthetic leg: “customizable, affordable and beautiful.”

Katie Albanese is a student in the Medical Physics Graduate Program who has been 3D printing breasts, abdominal skeletons, and lungs to test the coherent scatter x-ray imaging system she developed. Over spring break, I had the opportunity to talk with Katie about her work and experience. She uses the scatter x-ray imaging system to identify the different kinds of tissue, including tumors, within the breast. When she isn’t busy printing 3D human-sized breasts to determine if the system works within the confines of normal breast geometries, Katie enjoys tennis, running, napping and watching documentaries in her spare time. Below is the transcript of the interview.

How did you get interested in your project?

When I came to Duke in 2014, I had no idea what research lab I wanted to join within the Medical Physics program. After hearing a lot of research talks from faculty within my program, I ultimately chose my lab based on how well I got along with my current advisor, Anuj Kapadia in the Radiology department. He had an x-ray project in the works with the hope of using coherent scatter in tissue imaging, but the system had yet to be used on human-sized objects.

Could you tell me more about the scatter x-ray imaging system you’ve developed?

Normally, scatter in a medical image is actively removed because it doesn’t contribute to diagnostic image quality in conventional x-ray. However, due to the unique inter-atomic spacing of every material – and Bragg’s law – every material has a unique scatter signature. So, using the scattered radiation from a sample (instead of the primary x-ray beam that is transmitted through the sample), we can identify the inter-atomic spacing of that material and trace that back to what the material actually is to a library of known inter-atomic spacings.

Bragg diffraction: Two beams with identical wavelength and phase approach a crystalline solid and are scattered off two different atoms within it.

How do you use this method with the 3D printed body parts?

One of the first things we did with the system was see if it could identify the different types of human tissue (ex. fat, muscle, tumor). The breast has all of these tissues within a relatively small piece of anatomy, so that is where the focus began. We were able to show that the system could discern different tissue types within a small sample, such as a piece of excised human tissue. However, in order to use any system in-vivo, which is ideally the aim, you have to determine whether or not it works on a normal human geometry. Another professor in our department built a dedicated breast CT system, so we used patient scans from that machine to model and print an accurate breast, both in anatomy and physical size.

What are the three biggest benefits of the x-ray imaging system for future research?

Main breast phantom used and a mammogram of that phantom with tissue samples in it

Coherent scatter imaging is gaining momentum as an imaging field. At the SPIE Medical Imaging Conference a few weeks ago in San Diego, there was a dedicated section on the use of scatter imaging (and our group had 3 out of 5 talks on the topic!). One major benefit is that it is noninvasive. There is always a need for a noninvasive diagnostic step in the medical field. One thing we foresee this technology being used for could be a replacement for certain biopsy procedures. For instance, if a radiologist finds something suspicious in a mammogram, a repeat scan of that area could be taken on a scatter imaging system to determine whether or not the suspicious lesion is malignant or not. It has the potential to reduce the number of unnecessary invasive (and painful!) biopsies done in cancer diagnosis.

Another thing we envision, and work has been done on this in our group, is using this imaging technique for intra-operative margin detection. When a patient gets a lumpectomy or mastectomy, the excised tissue is sent to pathology to make sure all the cancer has been removed from the patient. This is done by assessing whether or not there is cancer on the outer margins of the sample and can often take several days. If there is cancerous tissue in the margin, then it is likely that the extent of the cancer was not removed from the patient and a repeat surgery is required. Our imaging system has the potential to scan the entirety of the tissue sample while the patient is still open in the operating room. With further refinement of system parameters and scanning technique, this could be a reality and help to prevent additional surgeries and the complications that could arise from that.

What was the hardest or most frustrating part of working on the project?

We use a coded aperture within the x-ray beam, which is basically a mask that allows us to have a depth-resolved image. The aperture is what tells us where the source of the scatter came from so that we can reconstruct. The location of this aperture relative to the other apparatus within our setup is carefully calibrated, down to the sub-millimeter range. If any part of the system is moved, everything must be recalibrated within the code, which is very time-consuming and frustrating. So basically every time we wanted to move something in our setup to make things better or more efficient, it was like we were redesigning the system from scratch.

What is your workspace like?

Katie and the team at the AAPM (American Association of Physicists in Medicine) conference from this past summer in Anaheim, CA where she presented in a special session on breast imaging. From left to right: Robert Morris (also in the research lab and getting his degree in MedPhys), Katie, Dr. James Dobbins III (former program director and current Associate Vice Provost for DKU) and Dr. Anuj Kapadia, my advisor and current director of graduate studies in the program

Katie presented in a special session on breast imaging at the American Association of Physicists in Medicine conference this past summer in Anaheim, CA. From left to right: Robert Morris, also working in the lab; Katie; Dr. James Dobbins III, former program director and current Associate Vice Provost for Duke-Kunshan University; and Dr. Anuj Kapadia, Katie’s advisor and current director of graduate studies.

We have a working experimental lab within the hospital. It looks like any other physics lab you might come across- messy, full of wires and strange electronics. It is unique from other labs within the Medical Physics department because a lot of research that is done there focuses on image processing or radiation therapy treatment planning and can be done on just a computer. This lab is very hands-on in that we need to engineer the system ourselves. It is not uncommon for us to be using power tools or soldering or welding.

What do you like best about 3D printing?

3D printing has become such a great community for creativity. One of my favorite websites now, called Thingiverse, is basically a haven for 3D printable files of anything you could ever dream of, with comments on the best printing settings, printers and inks. You can really print anything you want — I’ve printed everything from breasts, lungs and spines to small animal models and even Harry Potter memorabilia to add to my collection. If you can dream it, you can print it in three dimensions, and I think that’s amazing.

By Anika Radiya-Dixit

Why care about the gender gap in science and tech?

By Anika Radiya-Dixit

On March 2, 2016

In Computers/Technology, Data, Engineering, Mathematics, Physics, Science Communication & Education, Statistics

A day on the job for Christine McKinley

Scenes like the one above are engineer Christine McKinley’s favorite views of the construction sites where she manages building designs and contracts with other engineers. McKinley, a mechanical engineer, musician, and author, enjoys the complexities, high stakes and surprises of her job. Engineers, she says, “design against [surprises] but live for surprises.”

One of these surprises, McKinley told an audience last Thursday Feb. 25 in the Nelson Music Room at Duke, was a talk she had with the director of a community college district. He told her “women aren’t as good as math and science.” Shocked and disappointed that a man in charge of the education of the young students would believe this, McKinley pointed out that several of her accomplished colleagues were women. McKinley, like many other women, was frustrated that she has to work harder than men to get a promotion.

Is this changing? Are women today more prevalent in engineering fields than they were twenty to thirty years ago?

The chart below depicts the distribution of engineers in 1989: only 15 percent are women.

Distribution of Engineering Graduates in 1989

Of course, 1989 was 27 years ago and a different cultural time, with Nintendo’s Game Boy and Prince William’s seventh birthday. But the chart below shows how little those numbers have changed.

Distribution of Engineering Graduates in 2015

For mechanical engineers, the gap is much larger: only 7 percent are women (yellow faces), while the blue faces represent men, with the some frowning ones unhappy to be working with the women.

Percent of female mechanical engineers

When the workers are broken down into teams, according to McKinley, the image below is what it actually feels like to be working as a female mechanical engineer.

What it actually feels like to be a female mechanical engineer

Let’s start with the most troubling issue regarding the lack of diversity in engineering. If women and people of color are told that we are not good at math and science, and we believe it, then we are choosing a form of helplessness. Specifically, if we don’t pick apart the data and challenge those who made up this story, then it sticks, and the “rumor” becomes a narrative – and that’s dangerous, McKinley said. However, everyone needs to know basic chemistry, math, and physics to participate in conversations about topics such as medicine, NASA, one’s cholesterol level, and energy conservation as a knowledgeable adult. People need to be STEM-literate to be able to analyze this data, and men, especially in the 1950s, didn’t want women to research the facts and prove a competition.

Why should we care about women choosing careers in STEM fields?

Reason 1: Gender financial inequity: STEM grads make more than non-STEM grads

If we care about the gender pay gap, and only 19 percent of engineering graduates are women, then that aggravates the situation. This gender inequity can be addressed – partly – by women choosing to study engineering, McKinley said.

Of course, money is not the only thing in life; we want jobs with meaning, she added. However, even civil engineers understand that they are in a helping profession, always excited to build a new bridge, for example, to help people cross a flooded river. At the same time, money gives one the ability to leave a spouse, to take care of a disabled child, to find a better job, to afford healthier food; making real money gives one a way to become independent and make better choices. Working a job, however, does not imply that we must “sacrifice [our] life and fun.” McKinley enjoys what she does and has a lot of fun on the job; studying math and science, she says, is not that complex with the right motivation and support.

Reason 2: Humanity’s Survival

A coronal mass ejection (CME) is an enormous eruption of gas and magnetic field that launches billions of tons of plasma from the sun’s surface into space. Such an event occurred in 1859. As a result, farmers plowing field with horses noticed a bright flash of light, steam engines continued to run on schedule, and telegraph operators were confused when their telegraph batteries stopped working. Overall, there were few problems due to the limited technology at the time.

Imagine a CME happening today. All our large pieces of equipment – power stations, transformers, and transmission lines – would get fried.

Equipment involved in the transportation of energy from power plants to users

If these power houses blow up, what are we going to do? With three-year lead-time and $2 trillion cost, they will not be repaired in time for us to continue our daily functions. We now have a civilization-changing event on our hands – what Hurricane Katrina gave us, but now, for entire countries. We are in a time where our dependence on technology is constantly rising – until it’s not. In such a disastrous scenario, we will need more engineers. At this time, everyone – men and women – will come together to work on simple, elegant solutions to make the world better.

Currently, we have a mass shortage of engineers, so those today are overbooked with work. If these engineers are unable to find time to think through the entire solution and review all possible sources of error, then it creates a problem not only for engineering but also for the entire world in general. We are in need of good engineers and a diverse workforce to bring together all our ideas for a better world.

McKinley notes that she finds herself more comfortable when there are other women in the room. As a result, the whole team gets more relaxed, “elevating everyone’s game,” and people get more creative and feel more secure in sharing their ideas.

Grace Hopper created the computers advertised in this flyer.

Reason 3: The third reason we care about this view about engineering is the history of STEM achievements by women being ignored or the credit being taken by men.

Women who became mathematicians in the 1900s had to fight hard to have their contributions to the field recognized. The world misses out significantly if the achievements of half of humanity are ignored.

Hertha Aryton was a brilliant mathematician who had been elected the first female member of the Institution of Electrical Engineers in 1899. In 1902, she became the first woman nominated a Fellow of the Royal Society of London. “Because she was married, however,” McKinley quoted, “legal counsel advised that the charter of the Royal Society did not allow the Society to elect her to this distinction.”

Amalie Noether was another incredible mathematician who invented a theorem that united symmetry in nature and the universal laws of conservation. Some consider Noether’s theorem, as it is now called, to be as important as Albert Einstein’s theory of relativity. Einstein himself regarded her as most “significant” and “creative” female mathematician of all time. However, McKinley tells the audience, she was denied a working position at universities simply because they did not hire female professors.

In the 1900’s, more than 1000 women joined an organization called Women Airforce Service Pilots. They transported newly-made planes to the fighter pilots; however, many of the planes were untested, causing 38 of them to die in service. While they went through intense military training and had prior experience, the women were considered “civilian volunteers” and had to fight to be recognized. Further, most of the accepted women to the organization were white, and the only African American applicant was asked to withdraw her application.

Nancy Fitzroy was American engineer and heat transfer expert in the 1900s. She received plenty of criticism as well, but she said it didn’t affect her: “The reaction I pretty much have gotten most of my life is ‘little girl, what are you doing here?’ but I was a good engineer. That’s what made all the difference.”

Curiosity, inventiveness, and the urge to improve are not male traits. They are human traits. Women are half of humanity; they are not the spectators. Women must step up and contribute even if it is more difficult. Constantly underestimated as a female mechanical engineer, McKinley says she uses this underestimation as fuel to work harder and become better.

Being an engineer is worth it. Ask great questions, and be really good.

Remember, McKinley told her audience, that engineering is full of surprises. And for people who underestimate you, you’ll be that surprise.

—–

Christine McKinley gave her talk in the Nelson Music Building at Duke last Thursday for Feminist/Women’s month.

Christine McKinley is a mechanical engineer, musician, and author. Her musical Gracie and the Atom, won a Portland Drammy for Original Score. Her book Physics for Rock Stars was published in 2014 by Penguin Random House. Christine hosted Brad Meltzer’s Decoded on History Channel and Under New York on Discovery Channel.

You can view her website, read her book, or contact her via email.

—–

Anika_RD_hed100_2 By Anika Radiya-Dixit

3-D Movies of Life at Nanoscale Named Best Science Paper of the Year

By Robin Smith

On February 19, 2016

In Animals, Biology, Cancer, Computers/Technology, Physics

If you’ve ever wanted to watch a killer T cell in action, or see human cancer make new cells up-close, now is your chance.

A collection of 3-D movies captured by Duke biology professor Dan Kiehart and colleagues has won the 2015 Newcomb Cleveland Prize for most outstanding paper in the journal Science.

The paper uses a new imaging technique called lattice light-sheet microscopy to make super high-resolution three-dimensional movies of living things ranging from single cells to developing worm and fly embryos.

https://www.youtube.com/watch?v=fwzIUnKNw0s

Cutting-edge microscopes available on many campuses today allow researchers to take one or two images a second. But the lattice light-sheet microscope, co-developed by 2014 Nobel Prize winner Eric Betzig, lets researchers take more than 50 images a second, and in the specimen’s natural state, without smooshing it under a cover slip.

You can watch slender antennae called filopodia extend from the surface of a human cancer cell, or tiny rods called microtubules, several thousand times finer than a human hair, growing and shrinking inside a slide mold.

Daniel Kiehart and former Duke postdoctoral fellow Serdar Tulu made a video of the back side of a fruit fly embryo during a crucial step in its development into a larva.

Chosen from among nominations submitted by readers of Science, the paper has been viewed more than 20,000 times since it was first published on October 24, 2014.

The award was announced on February 12, 2016, at an award ceremony held during the annual meeting of the American Association for the Advancement of Science (AAAS) in Washington, D.C.

Winners received a commemorative plaque and $25,000, to be shared among the paper’s lead authors Eric Betzig, Bi-Chang Chen, Wesley Legant and Kai Wang of Janelia Farm Research Campus.

Read more: “Lattice light-sheet microscopy: Imaging molecules to embryos at high spatiotemporal resolution,” Chen, B.-C., et al. Science, October 2014. DOI:10.1126/science.1257998

Post by Robin A. Smith Robin Smith

What Came Before the Big Bang?

By Anika Radiya-Dixit

On February 2, 2016

In Data, Engineering, Mathematics, Physics

The Big Bang Theory: Origins of the universe.

Students and faculty gathered in the Physics building over coffee last Friday to understand the theory and mathematics behind a fundamental question: how did our universe start and what came before it?

Cosmologist and theoretical physicist Laura Mersini-Houghton, associate professor at UNC, is a proponent of the idea that our universe is one of many.

Laura Mersini-Houghton, associate professor of theoretical physics and cosmology at the University of North Carolina at Chapel Hill, has appeared on various TV and radio stations to discuss her theories on black holes and the origins of the universe.

With the rise of technology in the twentieth century, we now know more about the Big Bang and the dark energy that makes up approximately 70 percent of the universe. With the expansion of universe, all other matter — everything we have observed on Earth and through instruments — will dilute, while dark energy, which has constant density, will expand, thereby “pushing the universe apart.”

Expansion of the universe due to dark energy.

What has bothered scientists since the early 1970’s are the questions: what exactly selected the initial conditions of the universe? What determined the arrow of time? Why did we have to start with these very special conditions?

What brings these issues to the forefront of research today is that fact that dark energy will be the only thing remaining in the present timeline of our universe. In other words, we are going towards another big bang explosion. In order to predict how the future of the universe will evolve, we must first understand the mystery behind dark energy.

Dr. Mersini-Houghton says that the chances of a Big Bang happening by chance are 1 / 10^{10^123}, which is infinitely impossible. What selected this initial condition?

Illustration of the string theory landscape of multiple universes.

She proposes wave functions. When the energy of each wave function is at a tipping point, a new big bang occurs and with it another universe is created. With the support of the string theory, using one-dimensional strings in place of the particles of quantum physics, we calculate a landscape of 10^500 possible universes. The hypothesis that there exist other universes then raises the question: why did we start with this universe? Our universe is no longer at the center of the Cosmos as we previously believed; rather it is a humble member in a vastness.

Even if there are multiple universes, their entanglement with us is so tiny that they are nearly impossible to detect. However, the Planck satellite has found concrete scientific evidence of changes in energy due to other universes. According to Dr. Mersini-Houghton, atypical observations made about galaxies moving in the wrong direction and the unexplained “Cold Spot” in the cosmic microwave background are effects are due to the presence of neighboring universes.

In short, nature is a lot more complicated than we think it is, and simply looking at it and simplifying the problem to solely our world will not help us understand what is truly happening. To address the problem of our origins, perhaps we need to extend our paradigm of space-time and look for observational tests of a multiverse framework.

Stephen Hawking’s take on parallel universes in an interview.

Learn more about Mersini-Houghton’s multiverse theory and her latest research on Hawking radiation and black holes. To view a list of her talks, visit her webpage or send her an email at mersini@physics.unc.edu.

By Anika Radiya-Dixit.

Anika_RD_hed100_2

Measuring the Mechanical Forces of Disease

By Karl Bates

On January 5, 2016

In Biology, Biomedical Engineering, Cancer, Cardiology, Guest Post, Physics

“All these complicated diseases that we don’t have a good handle on — they all have this mechanical component. Well why is that?”

Brent Hoffman is an assistant professor of biomedical engineering

This is exactly the question Brent Hoffman, Duke biomedical engineering assistant professor, is helping answer. Many of the common diseases that we fear have a mechanical component. In asthma attacks, a chemical or physical stimulus causes the air channels in the lung to shut as the muscles that control the width of the channel contract– the mechanical component.

Another example is atherosclerosis, commonly known as the hardening of the arteries, the leading killer in developed countries. Instead of air flow, blood flow is affected as the walls of the blood vessels get thicker. Factors such as smoking, being overweight, and having high cholesterol increase the chance of getting this disease. However, examining the mechanical portion, the plaques associated with atherosclerosis tend to occur at certain parts of the blood vessels, where they branch or curve. You can think of it like a hose. When you kink a hose or put your thumb over the nozzle, the fluid flows in a different way. Hoffman said there are similar stories concerning mechanical portions of major diseases, such as muscular dystrophy and breast cancer.

Hoffman’s lab is building tension sensors to measure forces during collective cell migration.

This all sounds very biological, so why is he in the engineering department? As mechanobiology is a new field, there are few tools available for reporting a protein’s shape or its forces inside living cells. Hoffman makes the tools enabling the study of mechanobiology. During Hoffman’s postdoctoral research, he worked on recording forces across proteins in living cells, their natural environment. Now, he’s expanding that technology and using it to do basic science studies to understand mechanobiology.

Hoffman said he hadn’t planned this. From high school, he knew he wanted to be an engineer. As an undergraduate, Hoffman interned at IBM, where he worked on the production of chip carriers using copper-plating. Hoffman was able to apply knowledge, such as changing pH to get various amounts of copper, and make everything perform at optimal performance, but he wanted to know more about the processes.

So he set out to get his Ph.D in process control, which involves deciding how to set all the numbers and dials on the equipment, how large the tank should be, what pressure and temperature should be used, etc. in chemical plants. Hoffman was set on the path to become a chemical engineer. However, during the first week of graduate school, he attended a biophysics talk, in which he understood very little. Biophysics interested Hoffman, so he went from intending to do research on one of the most applied engineering projects on campus to arguably one of the least applied in a week. This was the beginning of his biophysics journey. However, as his Ph. D was much more heavily interested in the physics aspect, Hoffman chose to do his postdoc in cell biology to balance his training. Mixing everything together, he got biomedical engineering.

Hoffman reflects that his decisions were logical, but he had not planned to take the route he did. Hoffman cautions that it is better to have a plan than not because if you do not plan, you won’t know where you are going. However, he advises that since a person learns more about likes and dislikes as one proceeds on their route, students should not be afraid to incorporate what they learn into their plans.

Hoffman’s journey is characterized by finding and doing what he enjoyed. Trained in both the worlds of physics and biology, but never intending to pursue a future in either, Hoffman is uniquely suited for his current position in the revolutionary emerging field of mechanobiology. He is able to put his biology hat on and his physicist hat on for a bit, while the engineer in him is thinking, “is any of this practical?”
“If you had to pick out the key to my success, it would be doing that,” Hoffman said.

Guest Post by Amanda Li, a senior at the North Carolina School of Science and Math

Middle Schoolers Ask: What's it Like to be a Scientist?

By Robin Smith

On December 16, 2015

In Animals, Behavior/Psychology, Biology, Chemistry, Environment/Sustainability, Physics, Science Communication & Education, Students

When a group of local middle schoolers asked four Duke postdocs what it’s like to be a scientist, the answers they got surprised them.

For toxicologist Laura Maurer, it means finding out if the tiny silver particles used to keep socks and running shirts from getting smelly might be harmful to your health.

For physics researcher Andres Aragoneses, it means using lasers to stop hackers and make telecommunications more secure.

And for evolutionary anthropologist Noah Snyder-Mackler, it means handling a lot of monkey poop.

The end result is a series of short video interviews filmed and edited by 5th-8th graders in Durham, North Carolina. Read more about the project and the people behind it at http://sites.duke.edu/pdocs/, or watch the videos below:

Celebratory Bottles Mark the March of Time

By Guest Post

On November 17, 2015

In Faculty, Guest Post, Physics

The 50^th anniversary of the Triangle University Nuclear Laboratory (TUNL) November 6-8 was a homecoming of sorts for hundreds of alumni, faculty and friends.

On the eve of the anniversary party, Chris Gould of NC State inspecting the trophy case at TUNL.

On the eve of the anniversary party, Chris Gould of NC State inspected the trophy case at TUNL.

For half a century, the three Triangle universities have collaborated seamlessly on nuclear physics experiments using particle accelerators and other equipment too large and expensive for one university to effectively use on its own.

Key milestones in the lab’s history are marked by a dusty rank of empty champagne bottles marching across the top of a power supply cabinet in the basement lab.

Each trophy bottle records a moment of celebration, when faculty, researchers, technicians, and students gathered to savor an achievement made possible by years of working all hours of the day and night to design, build, measure, adjust, repair, monitor, and make sense of equipment and experiments. Each is labeled, typically in Wite-Out correction fluid, with a date and the event.

“The bottles represent technical milestones that either created new research opportunities at TUNL or increased the competitiveness of TUNL’s research activities in specific areas,” said Calvin Howell, who is a Duke professor and the director of TUNL.

December 29, 1968, the first beam of 30 MeV after two years of construction and assembly.

December 29, 1968, Roberson’s handwriting celebrates the first beam of 30 MeV, marking the end of two years of construction and assembly and the beginning of 50 years of science.

Russell Roberson, Duke professor emeritus and one-time TUNL director, started the tradition. On Sunday, December 29, 1968, TUNL physicists successfully coaxed a beam of particles out of the new equipment, marking the completion of two years of constructing a new building behind Duke’s physics building and installing enormous equipment purchased with a $2.5 million grant from the Atomic Energy Commission.

“It was a pretty big deal to have that beam and it seemed like we ought to remember when we did it,” Roberson said.

Graduate student Chris Gould had just driven from Philadelphia to Duke between Christmas and New Year’s day to deliver a piece of equipment with colleague Steve Shafroth, who was beginning his TUNL career at UNC. “We arrived in the evening,” remembered Gould, who is now a professor of physics at NC State. “And came upon a bibulous celebration in the control room where bottles of Cold Duck were being cooled down with liquid nitrogen and drunk out of paper cups.”

Six months later, Gould began his career at TUNL.

In the coming years, they would collide this type of beam (and others) with targets of various compositions in their quest to unlock the secrets of subatomic structure and forces.

Here are a few trophies from over the years:

July 14, 1983 – “Polarized Target – Polarized Beam.” Worth Seagondollar, chair of physics at N.C. State. (Courtesy of David Haase, NCSU)

May 13, 1979 – “First pulsed polarized n”

In the mid-1970s, TUNL began producing polarized neutron beams, in which the neutrons were all spinning in the same direction. Knowing the spin direction of the particles in the beam made for more precise interpretation of the data when the beam hit the target. This bottle from 1979 marked a further enhancement—the beam was pulsed so that the speed of the neutrons in the beam could be calculated.

July 8, 1980 – “First data taken with the VAX”

TUNL was the first nuclear lab to take data with the new 32-bit VAX computer from the Digital Equipment Corporation. TUNL physicists built an operating system to go along with it, which was used by many other labs around the world. In fact, Gould and Roberson traveled to China and Saudi Arabia to help labs there set up the same system. (Before the VAX, TUNL “borrowed” computer power from the high-energy physics group at Duke, via cables that ran through a 4” pipe between the two labs.)

May 15, 1992 – “Lamb Shift Polarimeter Bump Bump Bump”

TUNL faculty and students designed a device called a “Lamb shift spin-filter polarimeter” that would characterize the distribution of spin directions of the particles in a polarized beam almost instantly — a task that had previously taken hours. “We had just collected the first spectrum which proved that the Lamb-shift polarimeter could be used to determine the beam polarization in the predicted way,” recalled UNC professor Tom Clegg. “It was a night for high-fives and celebration. We joyously popped the cork on this bottle late on Friday evening after a very difficult week.”

"Bump Bump Bump" signified three distinct signals from the new Lamb shift spin-filter polarimeter.

1992 “Bump Bump Bump”

October 26, 2006 – “First Beam Extracted from Booster”

TUNL operates the world’s most powerful Compton gamma-ray source, called HIGS (which stands for high intensity gamma-ray source). The gamma rays are produced in a free electron laser ring, which is housed in a 52,000-square-foot building adjacent to the original TUNL facility on Duke’s campus. In 2006, TUNL scientists added a booster ring called a synchrotron to increase the intensity of gamma rays that could be produced. Scientists from all over the world use the facility for experiments involving gamma rays at energies of 10 million to 100 million electron volts (MeV).

Guest post by Mary-Russell Roberson

From Neutrinos to Nuclear Deals: Congressman Bill Foster

By Olivia Zhu

On November 6, 2015

In Lecture, Physics, Science Communication & Education

Hon. Bill Foster of the 11^th District of Illinois is the only member of Congress to hold a Ph.D. in science. On November 5^th, Congressman Foster visited Duke’s Initiative for Science and Society to discuss his unconventional path to politics and his consequent unique perspective. He lightheartedly delivered what he called a “recruiting speech” to a room full of scientists, hoping to persuade students with scientific background to become involved in public policy.

Representative Bill Foster, Ph.D., doing what politicians must.

Bill Foster started his first business with his brother at the age of 19 out of his family basement. His earnest, innovative efforts to use computers to control lighting manifested in the company Electronic Theatre Controls, which powered Disneyland and Disneyworld’s Parade of Lights in the 1980s, the 2012 London Olympic Stadium, Chicago’s Millenium Park, and a large portion of shows on Broadway.

Foster then transitioned into his career in physics. He undertook the IMB Proton Decay Experiment for his Ph.D. thesis under Larry Sulak; Foster did not observe proton decay, but he did observe neutrinos from a supernova. Foster continued his physics career at the Fermi National Accelerator Lab in suburban Chicago, where he smashed protons and anti-protons together at high speeds and later worked on the particle accelerators themselves.

In the midst of discovering Big Bang particles, Foster also fell into politics by maintaining an active civil engagement. He volunteered for Patrick Murphy’s campaign in 2006, where he says he “learned business on the factory floor,” a philosophy he has maintained since his days at Electronic Theatre Controls. He began the 110^th Congress as an intern for Rep. Patrick Murphy, and ended it sitting as a Congressman.

Hon. Foster graphs the relative numbers of scientists and engineers, lawyers, and career politicians in Congress. The U.S. Congress consists mostly of career politicians, explains Foster, while China, for example, consists mostly of engineers.

Rep. Foster plots the relative numbers of scientists and engineers, lawyers, and career politicians in international governing bodies. The U.S. Congress consists mostly of career politicians, explains Foster, while China, for example, consists mostly of engineers.

Since winning his seat in 2012, Foster has introduced a scientific perspective to Congress, even if he’s careful not to conflate that with his political stance. He makes a point to clarify technical details of issues like the Iran nuclear deals, human genetic engineering, and public key cryptography on cell phones, to ensure that Congress makes the most informed decisions possible on highly complicated ethical issues. On genetic engineering, he noted, “Our ethical paradigm is not set up for it,” as the notion of “All men are created equal” fundamentally cannot handle humans whose genetic traits are pre-picked. Clearly, scientific expertise will be invaluable in such consequential issues.

Life in Washington, Foster stated, is unromantic. Foster lives in efficiency apartments and grounds himself by holding “Congress on your Corner” events, where he answers any constituent questions, like why grout isn’t working on a driveway.

Political customs, such as the dilemma of which tie to wear to promote his campaign, still bewilder his scientific mind. Most of the votes he makes, like renaming a post office, or voting on an issue the President will inevitably veto, don’t really matter, he said.

But what makes politics worth it for him, Foster explained as he passed around his voting card, is the power to make a positive difference in issues that impact millions of people. Such ambitions transcend the boundaries between science and policy.

By Olivia Zhu