Brandeis in Aspen II: Physics of granular materials

This post is a companion to Brandeis in Aspen I, and describes a workshop attended by Bulbul Chakraborty and Aparna Baskaran at the Aspen Center for Physics. The format of Aspen workshops is different from the usual academic workshop.  Each day has just one or two talks, which are primarily self-organized on a volunteer basis among the participants.  The format is designed to encourage  physicists working in a particular area to share research findings and enable cross-pollination of ideas in an informal and loosely structured setting.

The workshop attended by Chakraborty and Baskaran was entitled “Fluctuation and Response in granular materials”. Granular materials are ubiquitous in nature and industry. Examples range from sand and other geological materials, food and consumer products, and pebble beds in nuclear reactors. Understanding and controlling the properties of granular materials impacts such diverse processes as oil recovery, nuclear pebble bed reactors, printing and copying, and pharmaceutical processing. Granular media pose difficult and unique scientific challenges that distinguish them from atomic, nano-scale, and colloidal materials. Being intrinsically out of thermal equilibrium, assemblies of grains readily become trapped in metastable states, are extremely sensitive to preparation conditions, and can have strongly time-dependent properties.  Relaxing the constraints of thermal equilibrium, however, offers an advantage by opening up possibilities for creating novel static and dynamic phases that have distinctive functional properties.

At Aspen, the one-on-one and small sub group interactions among the participants covered a wide range of topics that are at the forefront of materials research, however, the program as a whole primarily focused on two questions. The first question was: What do we understand about jamming of granular materials? Jamming is what occurs in everyday life when we are trying to get coffee beans out of a hopper and they suddenly stop flowing. We fix this by tapping on the hopper. But this same phenomenon when it happens in giant grain silos causes them to collapse. So, one of the challenges is to be able to predict jamming events. The role of the physicist here is to design and carry out experiments in minimal model systems and develop theoretical frameworks that lead to predictive models of observed phenomena. Statistical Mechanics provides a powerful theoretical tool to address this question and our own Professor Chakraborty is one of the leading experts in the theory of jamming. The participants at the workshop had several robust discussions on the current understanding of this phenomenon and theoretical and experimental challenges that remain to be addressed.

The second question that the workshop focused on was : How does a dense granular material behave when sheared? Granular materials are called rheological fluids in that they exhibit shear-thinning and shear thickening behavior. In everyday life, we are all familiar with shear thinning. When we squeeze a tube of toothpaste, we are shearing it and it flows onto our brush. But once on the brush it stays put. This behavior is called shear thinning. Understanding rheology of granular materials is important for diverse applications ranging from pharmaceutical processes to being able to print well. The participants discussed in detail the physics of sheared granular materials and shared insight obtained from theory, simulations and experiments.

All participants departed the workshop invigorated by the robust exchange of ideas, ready to address the challenges presented by these complex materials.

Brandeis in Aspen I: String theory and quantum information

The Aspen Center for Physics is a physics retreat in which groups of researchers in a given field gather for a few weeks during the summer to discuss the latest developments and create the next ones. This May, a record four Brandeis physicists — almost a quarter of the department — visited the Center at the same time, attending two different workshops. This posting is about a workshop attended by string theorists Matthew Headrick and Albion Lawrence (and co-organized by Headrick);  another posting will describe a workshop attended by condensed-matter theorists Aparna Baskaran and Bulbul Chakraborty (a member of the Center’s advisory board).  Entry into Aspen workshops is competitive, so this strong Brandeis representation is remarkable; as always, we punch above our weight.

Headrick and Lawrence attended the workshop Quantum information in quantum gravity and condensed matter physics.  This was a highly interdisciplinary workshop, which brought together specialists in quantum gravity, including Headrick and Lawrence; experts in quantum information theory; and experts in “hard” condensed matter physics (who study material properties for which quantum phenomena play a central role).

Quantum information theorists study how the counterintuitive features of quantum mechanics — such as superpositions of states, entanglement between separated systems, and the collapse of the wave function brought on by measurement — could be exploited to produce remarkable (but so far mostly hypothetical) technologies like teleportation of quantum states, unbreakable encryption, and superfast computation. What does this have to do with gravity? When we try to formulate a consistent quantum-mechanical theory of gravity — which would subsume Einstein’s classical general theory of relativity — the concept of information crops up in numerous and often puzzling ways. For example, Stephen Hawking showed in the 1970s that, on account of quantum effects, black holes emit thermal radiation. Unlike the radiation emitted by conventional hot objects, which is only approximately thermal, pure thermal radiation of the kind that Hawking’s calculation predicted cannot carry information. Many physicists (including Hawking) therefore originally interpreted his result as implying that black holes fundamentally destroy information, challenging a sacred principle of physics. Today, based on advances in string theory, physicists (including Hawking) generally believe that in fact black holes do not destroy the information they contain.  Rather, black holes hide information in very subtle ways, by scrambling, encryption, and perhaps quantum teleportation — in other words, the same kinds of tricks that the quantum information people have been inventing and studying independently at the same time.

Another connection between gravity and information is provided by the so-called “holographic principle”, which also arose in the study of black holes and which has been given a precise realization in the context of string theory. This principle posits that, due to a combination of gravitational and quantum effects, there is a fundamental limit to the amount of information (i.e. the number of bits) that can be stored in a region of space, and furthermore that limit is related to its surface area, not its volume. String theorists, beginning with the seminal work of Juan Maldacena, have uncovered a number of precise implementations of this principle, in which certain quantum theories without gravity are holograms of theories of quantum gravity.  This should provide an avenue for uncovering the “tricks” gravity uses to hide information, a subject Lawrence is active in.  An additional benefit of these implementations is that calculations in the nongravitational theories which seemed prohibitively difficult become fairly simple in the gravitational side; these include  the computation of interesting quantities in quantum information theory, an area in which Headrick has done influential work.

All of these issues and many others were discussed in Aspen. This rather unique workshop was a very fruitful exchange of ideas, with physicists from three fields learning from each other and forging new interdisciplinary collaborations, in a setting where the scenery matched the grandeur of the subject.

Justice Brandeis Semester Lecture Series on Mobile Apps and Game Design

Rob Lindeman ’87 (Assoc Prof of CS at WPI) gave a great talk to the Justice Brandeis Semester Mobile Apps and Game Design program students a week ago. He talked about his work in Virtual Reality and Augmented Reality. This is part of a series of lectures on Mobile Apps and Game Design. You can see the rest of the series at this link: including videos of past lectures and info about future lectures. Feel free to stop by if you are in the neighborhood. Lectures are Mondays 1-2 in Lemberg 55. We’ve also had talks by the CTO of the One Laptop Per Child program (Ed McNierny) and CTOs of a few mobile startups in the area. In two weeks, we’ll have Haggai Goldfarb ’85 talking about his Mobile Game company LiquidBits. These lectures are open to everyone and will be followed by demonstrations of the mobile app projects of the Justice Brandeis Semester students which all are invited to attend.

VIDEO: Rob Lindeman ’85 on “Virtual and Augmented Reality”

From bench to clinical trials: the rFIXFc story

BrandeisNOW has a new story about the development of recombinant Factor IX Fc,  a candidate drug for hemophila, currently in Phase III cliniical trials. The story behind the Fc fusion technology started in academic labs including Neil Simister‘s at Brandeis, led to a biotech startup (Syntonix), which was then acquired by Biogen Idec, who are now conducing clinical trials.

For more, see

Green chemistry guru

Yesterday’s online has a story on Brandeis Chemistry alum Paul Anastas (PhD ’90), currently Assistant Administrator of the U.S. EPA’s Office of Research and Development, describing him as a “‘Green Chemistry’ Guru Charting [a] New Course for EPA Science”, who advocates that companies can make money while making chemicals using environmentally safer approaches throughout the lifecycle

Susan Birren named Dean of Arts and Sciences

Brandeis President Frederick Lawrence today announced via e-mail that Professor of Biology Susan Birren will be the next Dean of Arts and Sciences. According to Lawrence’s e-mail:

An internationally recognized researcher in developmental neurobiology who studies how developing nerve cells respond to the local environment to create the nervous system, Susan is affiliated with the National Center for Behavioral Genomics and the Volen Center for Complex Systems.

Susan is a distinguished scholar, an experienced academic leader and a talented educator. She has the wisdom to promote what is essential to each of the disciplines in the Arts and Sciences while working closely with each of the four schools, the different groups within the schools, and across disciplinary boundaries.

For more, see the story at Brandeis NOW


Trimethoprim decorated beads for magnetically manipulating mammalian cells

Brandeis grad students Yue Pan (Chemistry) and Marcus Long (Biochemistry), together with postdoc Hsin-Chieh Lin and Professors Lizbeth Hedstrom and Bing Xu, have extended their previous work on 6 nm diameter magnetic nanobeads (comparable in size to a globular protein). They’ve shown that when decorated with the ligand trimethoprim, the nanobeads can be used to selectively bind to target E coli DHFR fusion proteins, and in addition can be used to manipulate live cells with a magnetic force. This work entitled “Cell Compatible Trimethoprim (TMP)-Decorated Iron Oxide Nanoparticles Bind Dihydrofolate Reductase (DHFR) for Magnetically Modulating Focal Adhesion of Mammalian Cells” is now online in the Journal of the American Chemical Society (JACS).

These small, magnetic beads are the first example of solid supported trimethoprim and have numerous advantages over larger traditional beads, including rapid purification, and ultra low non-specific binding. It is, however, their ability to affect live cells that is most important. In the paper they first show that Cos-1 and HeLa cells can be incubated with the beads for over 5 days with little cell death. These cells can subsequently be manipulated by transfection. Finally when exposed to a magnetic force, the focal adhesion of bead-treated Cos-1 cells can be manipulated.

See also: recommendation at Faculty of 1000

Life science grads and postdocs pack room for Career Panel

On Monday, Brandeis University hosted a Career Panel specifically devoted to discussing job opportunities and career paths for individuals with life science PhDs.  The event, sponsored by the Genetics Training Grant, was organized and hosted by Prof. Bruce Goode (Biology) and was very successful in drawing a crowd, with an audience estimated at 90 students and postdocs,

The professional credentials of the assembled panelists reflected the purpose of the seminar itself: a broad sweep of career paths each making use of post-secondary education in the life sciences.  Beyond professional success, the panel was further notable because it was composed largely of women, most of whom managed families along with their careers.

First, representing the academic research career path, was the likable Prof. Avital Rodal of the Brandeis Biology Department.  As a recent hire, Prof. Rodal was extensively queried about the process of applying and successfully being offered a tenure track academic position.  Prof. Rodal cited receiving her own grant funding as well as a strong record of publication as reasons for her success.  Michelle Hoffmann (Back Bay Life Sciences Advisors) has built a career in business and management consulting and discussed which skills from her academic training prepared her for her success in the consulting industry.  Shoumita Dasgupta is an eight year veteran of the teaching faculty at Boston University and advised the audience on how to obtain relevant teaching experience during graduate training and also described how her own career as an educator has begun to include higher positions (she is now an assistant dean) in the admissions department at the medical school.  Meredith LeMasurier works as an editor for the journal Neuron and provided insight into the process of academic publishing.  Her role in the organization involves assessing the merit of submitted articles in the context of the literature and coordinating the efforts of reviewers and authors.  Finally, Jake Harrison (Joule Unlimited) works as an experimental scientist for a small biotechnology sector company.  Jake noted that, like academia, the small company environment allows him to pursue a rigorous scientific agenda combined with the professionalism of a corporate workplace.

After brief introductory statements from each of the panelists, the floor was open for questions, and audience members were interested to learn about job availability and job security.  Jake advised trainees to invest time in building comprehensive profiles on employment focused social networking sites such as LinkedIn.  Shoumita urged students to build their professional network by talking about their career aspirations often with peers and mentors as opportunities can often arise through existing connections.  Michelle emphasized the importance of putting together a sharp professional resume (different than an academic CV) and doing ample homework before contacting a company.

After the event, attendees expressed great interest in having panels on a regular basis, with panelists from additional areas of the job market. A particular interest was in individuals employed by the government or working in a public health or in health policy related fields.

An over arching theme of the discussion was that jobs in any of the career paths are highly competitive but, nevertheless, many exciting options exist for individuals with PhDs in the life sciences.  Overall, given the highly pertinent career information and the opportunities to network directly with individuals in a variety of career paths, all trainees would be well advised to attend future versions of this career panel.

Protected by Akismet
Blog with WordPress

Welcome Guest | Login (Brandeis Members Only)