Dec
10
Teaser:

PLEASE NOTE: This is a WEBINAR

Accurate modeling of blood flow provides insights into arterial stent design, surgical planning, and analysis of stroke risk. Unfortunately, fully detailed modeling of the cardiovascular system is computationally impossible due to the enormous number of blood vessels in the body.  Instead, a common technique is to choose a small subset of arteries to model in detail while accounting for the "un-modeled" parts of the cardiovascular system through boundary conditions.  A popular tactic for deriving such a boundary condition is to...

Dec
06
Teaser:

I will summarize our current understanding on the relation between the evolution of black holes and galaxies in the local universe. I will show that the growth of supermassive black holes as traced by optically luminous active galactic nuclei is strongly linked to the on-going formation of stars in the bulge component of galaxies. It is likely that this co-evolution is driven by the accretion and radial transport of cold gas, but major mergers of galaxies are not the primary mechanism for doing this. I will show that the fuel source for the black hole growth may be mass loss from intermediate mass stars and that the black hole growth may be limited in part by feedback from supernovae...

Dec
04
Teaser:

Recent advancements in computational fluid dynamics have enabled researchers to efficiently explore problems that involve moving elastic boundaries immersed in fluids for problems such as cardiac fluid dynamics, fish swimming, and the movement of bacteria. These...

Dec
04
Teaser:

Given the complexity of the dynamics of a plasma, reductions are needed. The Hamiltonian framework offers various ways to carry out such reductions. I will introduce some of these methods by considering in particular the example of gyrokinetics, which is a kinetic model for plasmas in a strong magnetic field.

Dec
03
Teaser:

The defining feature of a black hole is its event horizon through which nothing can escape outward, not even light.  And yet black holes are responsible for the brightest sources that we observe in the universe, from gamma-ray bursts to quasars. Their enormous luminosity arises from the release of gravitational binding energy outside the horizon as material falls inward.  These black hole accretion flows exhibit extraordinary behavior, including outbursts, state transitions, and quasi-periodic variability, most of which continue to defy understanding but which must be related to the magnetohydrodynamic turbulence and radioactive thermodynamics that...

Nov
28
Teaser:

PLEASE NOTE: This is a WEBINAR

The displacement of a liquid by an air bubble is a generic two-phase flow that underpins applications as diverse as microfluidics, thin-film coating, enhanced oil recovery, and biomechanics of the lungs. I will present two intriguing examples of such flows where, firstly, oscillations in the shape of propagating bubbles are induced by a simple change in tube geometry, and secondly, flexible vessel boundaries that enable streamwise variations of the channel depth...

Nov
27
Teaser:

The DNA mismatch repair system is critical for accurate DNA replication.  This system is highly conserved across organisms ranging from bacteria to humans reflecting the importance of minimizing genomic defects during cell division. The mismatch repair protein MutS has been identified the key factor that detects base-base mismatches and insertion-deletion mismatches in double stranded DNA and signals for their repair.  Despite intense study, a temporally resolved understanding of the molecular details of the MutS:DNA interactions during mismatch repair initiation has been difficult to...

Nov
27
Teaser:

In this seminar, we will discuss how interactions between discrete electromagnetic (EM) emitters lead to a cooperative response of a metamaterial or cold atomic gas to an incident field.  We will examine a number of ways the cooperative response can be engineered and exploited. The interactions responsible arise from repeated scattering of the field between its discrete constituent elements. Our focus will be on metamaterials, which are composed of subwavelength circuit elements - or meta-atoms - whose electric and magnetic multipole interactions are governed by their design.  We also...

Nov
26
Teaser:

Cancer continues to elude us. Metastasis, relapse and drug resistance are all still poorly understood and clinically insuperable. Evidently, the prevailing paradigms need to be re-examined and out-of-the-box ideas ought to be explored. Recently, has become acknowledged that transformative convergence of physical sciences with life sciences can bring forth new perspectives for addressing major questions and challenges relating to cancer. Drawing upon recent discoveries demonstrating the parallels between collective behaviors of bacteria and cancer, I will present a new picture of cancer as a...

Nov
20
Teaser:

mso-bidi-font-style:italic">The problem of speciation and species aggregation on a neutral landscape, subject to random mutational fluctuations without selective drive, has been a focus of research since the seminal work of Kimura on genetic drift. This problem, which has received increased attention due to the recent development of a neutral ecological theory by Hubbell, bears comparison with mathematical problems such as percolation and...

Nov
19
Teaser:

Directed locomotion requires coordinated motor activity throughout an animal’s body. The nematode C. elegans, with only 302 neurons, offers an opportunity to understand how locomotion is organized by an entire motor system. We discovered that the mechanism that organizes undulatory locomotion in C. elegans is a novel form of sensory feedback within the motor circuit. Stretch-sensory feedback simply compels each body segment to bend in the same direction and shortly after the bending of the adjacent anterior segment. Remarkably, the entire...

Nov
17
Teaser:

Galaxy collisions and mergers are a common consequence of the structure formation in the universe. We know that they happen because we see a number of beautiful examples on the sky through the "eyes" of many astronomical observatories. It is also thought that almost every galaxy (including our own, the Milky Way) harbors a supermassive black hole at its center. I will discuss the "knowns" and "unknowns" in the evolution of supermassive black hole pairs that form in collisions of their host galaxies and end their cosmic journey when the two black
holes merge due to the emission of gravitational waves.

...

Nov
15
Teaser:

Dr. Robert Liu trained as a condensed matter experimentalist working on quantum transport and noise in mesoscopic semiconductors, but always believed that the true value of a physics doctorate was in learning how to think through and solve problems. As a graduate student at Stanford, he became fascinated with questions about the brain and memory, and decided to apply his quantitative training from physics to the study of neuroscience. He moved to the University of California at San Francisco’s Sloan-Swartz Center for Theoretical Neurobiology to begin postdoctoral work on studying the neural...

Nov
14
Teaser:

Granular materials exhibit large spatial variations in their response to external loading, whether static or dynamic. As such, continuum models of properties such as the shear modulus and sound speed often fail. A promising alternative is to build an understanding of bulk behaviors from measurements at the particle scale, by analogy with the statistical mechanics of thermal systems. I will describe experiments in which we utilize photoelastic particles and piezo-embedded 'smart' particles to explore how two familiar properties -- temperature equilibration and...

Nov
13
Teaser:

Motile immune cells like neutrophils (the most abundant type of white blood cell) track down invading microbes by chemotaxis, keep hold of them by adhesion, and neutralize them by phagocytosis.  We integrate concepts and tools from immunobiology and biophysics to examine the mechanistic underpinnings of this amazing, cross-disciplinary feat.  Single-live-cell experiments using micropipette manipulation, optical tweezers, and a new type of horizontal atomic force microscope allow us to assess the nano-to-microscale ingredients of one-on-one encounters between human neutrophils and their targets (such as opsonized...

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