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Event Date Summary
Paul Butler (Carnegie Institute of Washington) Thu. April 27th, 2017
4:00 pm-5:00 pm

Planets Around Nearby Stars

Modern science began with Copernicus speculating that the Earth is a
planet and that all the planets orbit the Sun.  Bruno followed up by
speculating that the Sun is a star, that other stars have planets, and
other planets are inhabited by life.  For this and other heresies,
Bruno was burned at the stake in a public square in Rome in 1600.
Astronomy and extrasolar planets were a really hot field at the time.

Over the past 20 years more than a thousand extrasolar planets have
been found,

Juan de Pablo (University of Chicago) Thu. April 20th, 2017
4:00 pm-5:00 pm
Nanoparticles in liquid crystals, and liquid crystals in nanoparticles.
 
Liquid crystals are remarkably sensitive to interfacial interactions. Small perturbations at a liquid crystal interface can in fact be amplified over relative long distances, thereby providing the basis for a wide range of applications. Our recent research efforts have focused on the reverse phenomenon; that is, we have sought to manipulate the interfacial assembly of nanoparticles or the organization of surface active molecules by controlling the structure of a liquid crystal. This presentation will consist of a review of the basic principles that are responsible for liquid crystal-mediated interactions,
Lutz Schimansky-Geier (Humboldt University at Berlin) Thu. April 13th, 2017
4:00 pm-5:00 pm

Active Brownian particles: From individual to collective behavior

Single self-propelled particles as well as ensembles of self-propelled particles are examples of non-equilibrium states and a topic of the interdisciplinary research at the borderline between physics and biology. Interesting examples of self-moving objects come from biology, these are bacteria, eukaryots, amoeba, insects, fishes and animals etc. But also in physics self-moving objects are known, which are active colloids and moving spots in reaction-diffusion systems.

I will review various models of self-propelled particles from a viewpoint of statistical physics. Special attention is payed to the influence of noise on the dynamics of single particles and on the exhibition of spatial structures in groups of interacting moving particles.

Cristina Marchetti (Syracuse) Thu. April 6th, 2017
4:00 pm-5:00 pm

Active Matter: from colloids to living cells

Collections of self-propelled entities, from living cells to engineered microswimmers, organize in a rich variety of active fluid and solid states, with unusual properties. For instance, active fluids can flow with no externally applied driving forces and active gases do not fill their container. In this talk I will describe the behavior of such “active materials”, focusing on two examples of liquid-solid transitions driven by active processes. The first is the formation of cohesive matter with no cohesive forces in collections of purely repulsive active colloids. The second describes the properties of epithelial tissues that exhibit a liquid-solid transition at constant density driven by cell motility,

Michael Weiss (CWRU Biochemistry) Thu. March 30th, 2017
4:00 pm-5:00 pm

Origins, Evolution and Biophysics: an Ephemeral Golden Braid

Douglas Hofstradter’s celebrated 1979 book, Gödel, Escher, Bach: An Eternal Golden Braid (“GEB”), presented “a metaphorical fugue on minds and machines in the spirit of Lewis Carroll.”  In this talk we likewise seek to explore implicit themes and hidden connections that unite origins and evolution (in a broad sense) with biophysical principles underlying modern biochemistry and molecular genetics. Three vignettes will be presented in which an evolutionary perspective provides coherence to a clutter of molecular details. Just as GEB sought to decipher how systems acquire meaning despite being made of meaningless elements,

Mark Wise (Caltech) Note non-standard time Thu. March 23rd, 2017
4:30 pm-5:30 pm

Dark Matter Bound States and Indirect Dark Matter Signals

Most of the mass density in our universe is not composed of the familiar particles that make up atoms. Rather it is something different that goes by the name dark matter. We have considerable evidence for dark matter, for example, through of its gravitational influence on the motion of stars. The current theory of elementary particles has no candidate for the dark matter and it is probably a new type of particle. A number of experiments search for dark matter including the direct detection experiments which look for its scattering off nuclei.  

Herbert Levine (Rice Bioengineering) Thu. March 9th, 2017
4:00 pm-5:00 pm

Can theoretical physics help cancer biology? The case of metastatic spread

In order to spread from the primary tumor to distant sites, cancer cells must undergo a coordinated change in their phenotypic properties referred to as the “epithelial-to-mesenchymal” transition.  We have studied the nonlinear genetic circuits that are responsible for this cellular decision-making progress and propose that the transition actually goes through a series of intermediate states. At the same time, we have formulated motility models that allow for the correlation of state of this network and the cell’s biophysical capabilities. Hopefully, these efforts will help us better understand the transition to metastatic disease and possible treatments thereof.

Glenn Starkman (Physics) Thu. March 2nd, 2017
4:00 pm-5:00 pm

An Uncooperative Universe: Large Scale Anomalies in the CMB

The Cosmic Microwave Background Radiation is our most important source of information about the early universe. Many of its features are in good agreement with the predictions of the so-called standard model of cosmology — the Lambda Cold Dark Matter Inflationary Big Bang Theory. However, the large-angle fluctuations of the microwave background are uncooperative with “the program” — they continue to exhibit several statistically significant anomalies. On the one hand, if we look at the whole sky the lowest multipoles seem to be correlated both with each other and with the geometry of the solar system.

Corbin Covault (CWRU) Thu. February 23rd, 2017
4:00 pm-5:00 pm
A Cosmic Ray Astrophysicist’s Approach to the Optical Search for Extra Terrestrial Intelligence
 
For decades scientists have been searching the skies for signals from extraterrestrial civilizations using large radio telescopes.  Motivation for these searches is strengthened by the discovery that earth-like planets capable of sustaining life are ubiquitous.  Several new initiatives in the Search for Extra-Terrestrial Intelligence are underway.   In particular, some researchers have realized that signals sent at optical wavelengths may be promising as a plausible means of interstellar communications.  Such signals may be sent in the form of nanosecond light pulses generated by large lasers. 
Thu. February 16th, 2017
4:00 pm-5:00 pm
The 2016 Science Nobel Prizes – What were they given for? Thu. February 9th, 2017
4:00 pm-4:00 pm

Harsh Mathur on the prize in Physics; Michael Hinczewski on the prize in Chemistry; and Alan Tartakoff on the prize in Physiology or Medicine. Followed by a reception. 

Abstracts

The Nobel Prize in Physics for 2016 was awarded to David Thouless, Duncan Haldane and Michael Kosterlitz for the discovery of states of matter and transitions between these states of matter that could not be understood in terms of the conventional Landau paradigm. Harsh will review the Landau paradigm and describe the specific discoveries for which the prize was awarded: the explanation of a mysterious phase transition in films of superfluid helium by Kosterlitz and Thouless;
Thu. February 2nd, 2017
4:00 pm-5:00 pm
Lucile Savary (MIT) – Michelson Postdoctoral Prize Lecture Thu. January 26th, 2017
4:00 pm-5:00 pm

Quantum Spin Liquids

The search for truly quantum phases of matter is one of the center pieces of modern research in condensed matter physics. Quantum spin liquids are exemplars of such phases. They may be considered “quantum disordered” ground states of spin systems, in which zero point fluctuations are so strong that they prevent conventional magnetic long range order. More interestingly, quantum spin liquids are prototypical examples of ground states with massive many-body entanglement, of a degree sufficient to render these states distinct phases of matter. Their highly entangled nature imbues quantum spin liquids with unique physical aspects,

Kathy Kash (CWRU Physics) Thu. January 19th, 2017
4:00 pm-5:00 pm

Nitride Semiconductors: Beyond the Binaries

The binary nitride semiconductors and their alloys have led to transformations in both lighting and power electronics. They have also given us new physics such as polarization-induced topological insulators. But nitride semiconductors can be built of more than two elements. What new science and technology might we expect from such increased complexity? 


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