Bulletin of the American Physical Society
2016 Annual Meeting of the APS Mid-Atlantic Section
Volume 61, Number 16
Saturday–Sunday, October 15–16, 2016; Newark, Delaware
Session H3: Biophysics and Medical Physics III |
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Chair: Ed Lyman, University of Delaware Room: Sharp Laboratory 131 |
Sunday, October 16, 2016 3:30PM - 4:06PM |
H3.00001: Optical beam shaping and microscopy methods for biological and biomedical imaging applications Invited Speaker: Thomas Planchon While observing live biological specimens under the fluorescence microscope, scientists encounter a critical barrier defined as phototoxicity, which is the degeneration of a specimen under the light exposure. In this presentation, we will review how changing the geometry of excitation and collection of the light paths in a fluorescent microscope, by generating a sheet of excitation light, can overcome limitations given by phototoxicity. This new geometry allows improving the spatial resolution of the microscope to obtain isotropic resolution, 3D fast imaging and low phototoxicity, and obtain previously inaccessible dynamic information about biological processes, for example during cell proliferation and cell migration. For imaging single cells with sufficient spatial resolution and field of view, a Bessel beam light-sheet microscope was developed, in which a Bessel beam was generated using a fixed amplitude mask and then used for the excitation light instead of Gaussian beam. The separate geometry of excitation and detection also provides freedom to act on each of them separately with adaptive optics or beam shaping techniques, to improve imaging when aberrations are present or to lower phototoxicity by generating a thinner sheet of excitation light and a more versatile instrument [Preview Abstract] |
Sunday, October 16, 2016 4:06PM - 4:18PM |
H3.00002: Stirring a Low Reynolds Number MARTINI Andrew Zgorski, Edward Lyman Hydrodynamic interactions are an important component of lipid membrane dynamics. A proper molecular dynamics simulation of lateral diffusion in a membrane requires coupling to hydrodynamic flows in the surrounding solvent. In the low Reynolds number limit, the interactions mediated by these flows are long-ranged. When periodic boundary conditions are used with typical simulation sizes, these interactions lead to finite-size effects that inhibit diffusion. The system sizes required to adequately simulate lateral diffusion are computationally prohibitive when using explicit solvent models due to the number of pairwise solvent-solvent interactions. However, implicit solvent models entirely neglect hydrodynamic momentum transport. To remedy this, we have supplemented the Dry MARTINI implicit solvent model with an efficient mesoscopic particle-based hydrodynamic model called Stochastic Rotation Dynamics (SRD). Our implementation allows for fine control over fluid properties of the solvent, such as viscosity and Reynolds number, and includes a thermostat for the solvent that produces canonical energy fluctuations without interfering with the mesoscopic hydrodynamic flows. [Preview Abstract] |
Sunday, October 16, 2016 4:18PM - 4:30PM |
H3.00003: Fullerene Nanobombs for Specific Treatment of Alzheimer Disease (AD): A New Concept in AD Theranostics Heejae Chung, Joshua Kim, Andrew Rhee, Seong Hyeon Lee When fullerene particle becomes reactive, it easily gives off electrons by the molecular dynamics, and it helps to stabilize the cell affected by Alzheimer Disease caused by the Reactive Oxidative Species (ROS). This project aims to determine the thermodynamic stability of various compounds in Fullerene and its derivatives using a computational quantum physics and chemical physics. Density Functional Theory (DFT) and molecular mechanics are used in order to model the electron properties of the compound. Through the simulation, better and safer functional groups with fullerene, which can be used in the AD treatment with less optimization energy, were found by checking their optimized molecular energy both stereo-chemically and thermo-dynamically. Using the Avogadro and Gamess that allow performing such computations for the compounds, this program shows the optimized geometry energy levels of Fullerene Nano Molecules Used in PDT (Photodynamic Therapy) and fully determines the theoretical values of the structure’s atomic properties. [Preview Abstract] |
Sunday, October 16, 2016 4:30PM - 4:42PM |
H3.00004: Multi-layer Mechanical Model of Glagov Remodeling in Coronary Arteries: Differences between In-vivo and Ex-vivo Measurements Pak-Wing Fok When blood vessels undergo remodeling because of the buildup of atherosclerotic plaque, it is thought that they first undergo compensatory or outward remodeling, followed by inward remodeling: the lumen area stays roughly constant or increases slightly and then decreases rapidly. The second phase of remodeling is supposed to start after the plaque burden exceeds about 40\%. These changes in the vessel were first observed by S. Glagov who examined cross-sections of coronary arteries at different stages of the disease. In this presentation, we use a mechanical model based on growth and elasticity theory to verify the main aspects of Glagov's result. However, both our model and curve-fitting to the data suggest that the critical stenosis is around 20\% rather than 40\%. Our model and data from the PROSPECT trial also show that Glagov remodeling is qualitatively different depending on whether measurements are taken {\it ex-vivo} or {\it in-vivo}. Our results suggest that the first outward phase of ``Glagov remodeling'' is largely absent for {\it in-vivo} measurements: that is, the lumen area always decreases as plaque builds up. We advocate that care must be taken when infering how {\it in-vivo} vessels remodel from \exvivo data. [Preview Abstract] |
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