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...

Nov
08
Teaser:

The statistics of newly discovered z>~6 galaxies---their abundance and clustering---have allowed us to study their ensemble properties, but the difficulties inherent in detecting, resolving, and obtaining spectra of these distant, faint objects has prevented a deeper empirical exploration of their internal physics. However, in advance of observatories like GMT and TMT, multi-wavelength observations can be a useful probe of the high-redshift ISM. I will present a novel analytic model for the internal physics of z>~6 galaxies that, when combined with information from galaxy statistics, probes an enormous range of distance scales---from the tens of megaparsec regions over which...

Nov
08
Teaser:

In recent years, experiments with ultracold atoms [1,2,3,4] have investigated transport properties of one-dimensional (1D) Bose gases in optical lattices and shown that the transport in 1D is drastically suppressed even in the superfluid state compared to that in higher dimensions. Motivated by the experiments, we study superfluid transport of 1D Bose gases. In 1D, superflow at zero temperature can decay via quantum nucleation of phase slips even when the flow velocity is much smaller than the critical velocity predicted by mean-field theories. Using instanton techniques, we calculate the...

Nov
07
Teaser:

Motivated by issues related to treating certain neurological diseases such as Parkinson’s disease by a method called electrical deep brain stimulation, we consider applying optimal control methods to both mathematical models of neurons and in vitro neurons. Patients suffering from Parkinson’s disease experience involuntary tremors that typically affect the distal portion of their upper limbs. It has been hypothesized that these tremors are associated with simultaneous spiking of a cluster of neurons in the thalamus and basal ganglia regions of the brain. In a healthy situation, the periodic firing of neurons is not synchronized, but they can engage in a pathological synchrony...

Nov
05
Teaser:

Condensed matter physics in the 20th Century was developed mostly for crystalline solids, and we know so little about the physics of liquids and glasses.  We do not even know how to describe the structure of these amorphous matters to discuss the structure-properties relationship, even though liquids and glasses are so important to everyday life.  This is because liquids and glasses are condensed matter with high density in which atoms are strongly correlated to each other.  Any theoretical effort runs into a thick barrier of many-body interactions.  To circumvent...

Nov
01
Teaser:

Do you think Physics is only about stars and mad scientists? Come to this event and you will discover a new Physics world where fundamental physics knowledge is used “as simply as possible but not simpler” to build atom by atom the technology of future.  Come and learn how we make the smallest electronic circuits in the world, how we can build devices that power your cell phone while you walk in the streets, or how we pull single DNA molecules to understand the secrets of life.

Nov
01
Teaser:

I present a new numerical code constructed to obtain accurate simulations of encounters between a star and a massive black hole. The relativistic tidal interaction is calculated in \emph{Fermi normal coordinates} (FNC). This formalism allows the addition of an arbitrary number of terms in the tidal expansion. Although Newtonian hydrodynamics and self-gravity is assumed for the star, there are several significant terms in the expansion that should be retained. I give the relevant orbital post-Newtonian terms. The three-dimensional parallel (MPI) code includes a PPMLR hydrodynamics module to treat the gas dynamics and a Fourier transform-based method to calculate the self-gravity. Results...

Oct
29
Teaser:

Oct
25
Teaser:

A novel thermal scanning probe lithography (tSPL) method based on the local removal of organic resist materials has been developed at the IBM Research Laboratory in Zurich [1-3]. A polymeric polyphthalaldehyde resist [2-4] responds to the presence of a hot tip by local material decomposition and desorption. Thereby arbitrarily shaped patterns can be written in the organic films in the form of a topographic relief, constrained only by the shape of the tip. The combination of the fast ‘direct development’ patterning of a polymer resist and the in-situ...

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