aspuru-list April 2015

aspuru-list@lists.fas.harvard.edu

28 participants
68 discussions

[Aspuru-Guzik group list] Fwd: [Biophysics-Seminar] Today: MIT Physics Colloquium: Arup Chakraborty

by Semion Saikin

---------- Forwarded message ---------- From: Kerry P Forristall <kerryf(a)mit.edu> Date: Thu, Apr 30, 2015 at 9:20 AM Subject: [Biophysics-Seminar] Today: MIT Physics Colloquium: Arup Chakraborty To: "biophysics-seminar(a)mit.edu" <biophysics-seminar(a)mit.edu> *The David and Edith Harris Physics Colloquium Series* *Thursday, 4/30/15 in room 10-250* Arup Chakraborty MIT "Bringing Together Physics, Biology, and Medicine to Hit HIV Where It Hurts" HIV is a highly mutable virus, which evades natural and vaccine-induced immune responses and is the causative agent for the AIDS epidemic. I will describe methods, rooted in statistical physics, which aim to determine the fitness landscape of HIV – i.e., a definition of the collective sets of mutations that allow the virus to maintain fitness and evade immunity, and those combinations of mutations that cripple it. The “Hamiltonian” that describes this fitness landscape is analogous to the Hopfield Hamiltonian for associative memory in neural networks. I will show how this Hamiltonian reveals encoded “memories” in the HIV population of host-pathogen riposte won by the virus, and scaling laws that describe this phenomenon. I will also present how evolutionary dynamics with our inferred fitness landscape can predict HIV evolution in individual patients, and how we have harnessed this knowledge, along with other experimental tests, to design a therapeutic vaccine against HIV which is being advanced to pre-clinical trials. Time: 4:00pm Place: 10-250 Refreshments at 3:30pm in 4-349 (Pappalardo Community Room) Physics Colloquia Schedule: http://web.mit.edu/physics/events/colloquia.html <https://urldefense.proofpoint.com/v2/url?u=http-3A__web.mit.edu_physics_eve…> _______________________________________________ biophysics-seminar mailing list biophysics-seminar(a)mit.edu http://mailman.mit.edu/mailman/listinfo/biophysics-seminar -- ******************************************** Semion K. Saikin, PhD Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street, Cambridge, MA 02138 email: saykin(a)fas.harvard.edu phone: (619)212-6649 ********************************************

8 years, 12 months

[Aspuru-Guzik group list] [qip] Friday May 1

by Edward Farhi

Hi Quanta Tomorrow we will meet at 11:00 as usual. Kevin Zatloukal will join us and tell us some stuff. We are pushing Robin, Ted and Guang Hao to later meetings. See you there! Eddie Edward Farhi Director Center for Theoretical Physics Massachusetts Institute of Technology farhi(a)mit.edu _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

8 years, 12 months

[Aspuru-Guzik group list] May 7/8: meet with Shaul Mukamel

by Joey Goodknight

Hello Everyone Professor Shaul Mukamel of UC Irvine is coming to visit Harvard for theochem on May 7th and 8th and I've got lunch and dinner spots both days and plenty of meeting spots as well. Please let me know if you would like a meeting and/or a meal http://mukamel.ps.uci.edu/ -Joey

8 years, 12 months

[Aspuru-Guzik group list] ITAMP lunch seminar - Sarah Mostame, ITAMP (05/01)

by Richard Schmidt

Dear colleagues, this week we have Sarah Mostame, a new ITAMP-affiliated postdoc as speaker at our seminar. Kind regards, Richard and Swati ITAMP Topical Lunch Discussion Date: Friday, May 1st Time: 12:00-1:30 pm Pizza will be served. Location: B-106 @ Center for Astrophysics (60 Garden Street) Directions: after entering the lobby of the CfA, turn right to enter the hallway of the B building. In the hallway, turn right again, and B-106 is there. Speaker: Sarah Mostame, ITAMP Title: Analog and Digital Quantum Simulators Abstract: Problems associated with quantum many-body systems are notoriously difficult to solve even with modern digital computers. Feynman envisioned an approach to solve these problems by using one quantum system as a platform for simulating another, a technique that now is referred to as quantum simulation. There are two main approaches to quantum simulation: digital and analog. Digital quantum simulation exploits the universality of a quantum computer to carry out the simulation, whereas analog quantum simulation requires that one engineers a specific quantum system that generally is only applicable to a specific simulation or a small class of simulations. In this talk, I will briefly talk about analog quantum simulators and then will focus on the digital approach. --------------------------- Dr. Richard Schmidt Institute for Theoretical Atomic, Molecular, and Optical Physics (ITAMP) Harvard-Smithsonian Center for Astrophysics MS-14 60 Garden St. Cambridge, MA 02138 U.S.A. richard.schmidt(a)cfa.harvard.edu Tel. +1 (617) 496-7610 Fax +1 (617) 496-7668

8 years, 12 months

[Aspuru-Guzik group list] [Aspuru-meetings-list] Group Meeting, 4/30, Div. Room 2:30pm

by Jennifer Wei

Hi Everyone, Tomorrow Jacob will be giving us group meeting. Please see below for the title and abstract of his talk. Jennifer ----------------------------------- Title: Uncovering and Exploiting Sparsity in Neural Networks Abstract: Neural networks exhibit various kinds of sparsity. The most obvious type of sparsity is the structural connectivity of the network: relatively few neurons are synaptically linked to each other. I will begin by reviewing an experimental proposal to recover the sparse connectivity matrix by randomly expressing green fluorescent protein in various neurons and then applying compressed sensing to recover the connectivity. Moving beyond structural sparsity, I will discuss the idea of "functional sparsity"--the idea that while a neural network is governed by a vast number of microscopic parameters, only a few combinations of these parameters might be relevant to the macroscopic behavior of the network. In particular, I will propose that the recent idea of parameter space compression could be applied to neurons to find a minimal set of macroscopic characteristics required to describe a neural network, and illustrate how it might work within the context of a model for learning and memory known as spike-time-dependent plasticity. _______________________________________________ Aspuru-meetings-list mailing list Aspuru-meetings-list(a)lists.fas.harvard.edu https://lists.fas.harvard.edu/mailman/listinfo/aspuru-meetings-list

8 years, 12 months

[Aspuru-Guzik group list] [qip] Now

by Edward Farhi

Hi Han-Hsuan is having his defense now. ~~Eddie~~ _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

8 years, 12 months

[Aspuru-Guzik group list] TODAY: Special HQOC Seminar: Gonzalo Agustin Alvarez 4PM (Lyman 425)

by Coleman, Karl

There will be a Special HQOC Seminar today, Wednesday, April 29, at 4 PM in Lyman 425. Gonzalo Agustin Alvarez will be visiting from the Weizmann Institute of Science and will present the following talk: Localization Effects and Hyperpolarization in Many-Spin Networks. Please see the attached flyer for details. Karl Karl Coleman HQOC Laboratory Administrator Faculty Assistant to Profs. Greiner and Lukin Harvard University Department of Physics 17 Oxford Street Cambridge, MA 02138 P: (617) 496-2544 F: (617) 496-2545

8 years, 12 months

[Aspuru-Guzik group list] Joint P-Chem/Excitonics Seminar - Tues. May 5, 4-370

by Catherine M Bourgeois

Please post and forward to your group(s). Joint Seminar: Physical Chemistry and Center for Excitonics Navigating Space-Time with Ultrafast Exciton Photolithography or Scintillating Near-fields to Follow Dynamic Processes in Molecular Materials May 5, 2015 at 4:30pm/ rm: 4-370 Naomi Ginsberg University of California/Department of Chemistry and Physics [nsginsberg] abstract: A cross-cutting theme in my research group is to examine dynamic processes in spatially-heterogeneous condensed phase molecular materials over a wide range of time scales. I will share recent results in multiple areas, all underpinned by the strong correlation between physical structure and the optical properties of materials. Our investigations often require tailoring the spatial and temporal resolution of our measurement approaches. I will explain how by measuring the ultrafast electronic properties of heterogeneous, ‘printed’ semiconducting films of small organic molecules we infer the much slower dynamics by which complex nanoscale structural motifs in the films emerge when they self-assemble in an evaporating solvent. These studies reveal the generation of non-equilibrium nanoscale structures that arise from coupling the dynamics of fundamental phase transformation processes of solute crystallization with solvent evaporation. They also pinpoint the challenges associated with developing high carrier mobility materials for printed plastic electronics. The migration of Frenkel excitons, tightly-bound electron-hole pairs, in organic and hybrid organic-inorganic semiconducting films is critical to the function of many next generation optoelectronic devices. While these materials can exhibit a high degree of structural heterogeneity on the nanoscale, traditional measurements of exciton diffusion lengths are performed on bulk samples. Since both the characteristic length scales of structural heterogeneity and the reported bulk diffusion lengths are typically smaller than the optical diffraction limit, I will describe how we adapt far-field super-resolution fluorescence imaging to determine in-situ exciton diffusivities and to uncover the correlations between the structural and energetic landscapes that the excitons explore. Motivated by the need to observe the dynamics of biomolecular interactions on their characteristic length scales, I will also show how we have appropriated the nanoscale resolution of electron microscopy and the near-field luminescence properties of scintillating oxide films to non-invasively image soft materials that cannot be interrogated directly with a damaging electron beam. In addition to focusing on soft materials in organic electronics and biology, I will also demonstrate this new imaging modality applied to plasmonic nanostructures. bio: Naomi Ginsberg received a B. A. Sc. from the University of Toronto (Engineering Science) (2000) and a Ph.D. from Harvard University with the Physics – Hau group (2007). From 2007 – 2010, she was a Postdoctoral Fellow in the Physical Biosciences Division-Fleming group at the Lawrence Berkeley National Laboratory. Awards include UC Berkeley Department of Chemistry Teaching Award (2013), DARPA Young Faculty Awardee (2012), Packard Fellow for Science and Engineering (2011), and Cupola Era Endowed Chair in the College of Chemistry (2010-2012). Her group focuses on visualizing ultrafast energy flow in natural and artificial light harvesting systems and on combining electron and optical microscopies to facilitate high-resolution studies of living things and molecular interactions in solution. Naomi’s background in chemistry, physics, and engineering has led her to observe coherent and previously obscured energy transfer in light harvesting complexes from plants, to develop polarization techniques in ultrafast multidimensional spectroscopy to extract structure from electronically-coupled systems, to slow, stop, and store light pulses in some of the coldest atom clouds on Earth, and to discover, follow, and understand the interactions of superfluid nonlinear excitations.

8 years, 12 months

[Aspuru-Guzik group list] Group Pictures after group meeting

by Joey Goodknight

Hello All, Just a reminder/notification if you weren't at group meeting that we're doing group pictures after group meeting this Thursday: about 3:30 pm (15:30 for those of you from across the Atlantic). Thanks and have a great week! -Joey

8 years, 12 months

[Aspuru-Guzik group list] Fwd: Announcement for Today's Harvard Physics Colloquium Speaker: May-Britt and Edvard Moser, NTNU, Norway on 04/27/15

by Ian Kivlichan

Today's physics colloquium (4:15, tea at 3:30) is being given by the 2014 Nobel Prize Winners in Medicine or Physiology, covering the work that won them the prize. Should be interesting! Best, Ian ---------- Forwarded message ---------- From: "Maynard, Dayle" <maynard(a)fas.harvard.edu> Date: Apr 27, 2015 12:54 PM Subject: Announcement for Today's Harvard Physics Colloquium Speaker: May-Britt and Edvard Moser, NTNU, Norway on 04/27/15 To: "faculty(a)physics.harvard.edu" <faculty(a)physics.harvard.edu>, " grads(a)physics.harvard.edu" <grads(a)physics.harvard.edu>, " sps-list(a)hcs.harvard.edu" <sps-list(a)hcs.harvard.edu>, " research(a)physics.harvard.edu" <research(a)physics.harvard.edu> Cc: "Blum, Kenneth" <kenneth_blum(a)harvard.edu>, "Cho, Grace" < gcho(a)fas.harvard.edu>, "Cicerano, Michelle" <mcicerano(a)mcb.harvard.edu>, "Erel Levine @FAS" <elevine(a)fas.harvard.edu>, "samuel(a)physics.harvard.edu" < samuel(a)physics.harvard.edu>, "Aravi Samuel (adtsamuel(a)gmail.com)" < adtsamuel(a)gmail.com> Harvard Physics Colloquium > > Monday, April 27, 2015 > > 4:15 p.m.-5:15 p.m. in Jefferson 250 > > Tea served in Jefferson 450 @ 3:30 p.m. > > > > *"Grid Cells and Neural Maps for Space"* > > > > May-Britt and Edvard Moser > > *NTNU* > > For announcement poster please go to: > http://www.physics.harvard.edu/events/colloquium.pdf > > > > > > The medial entorhinal cortex (MEC) is part of the brain’s circuit for > dynamic representation of self-location. The metric of this representation > is provided by grid cells, cells with spatial firing fields that tile > environments in a periodic hexagonal pattern, like holes in a bee hive. > > > > In the first part of the talk, we will examine the mechanisms that > determine how the grid pattern is positioned relative to the external > environment. Data were collected from grid cells while rats foraged > randomly in square enclosures. We will show that the axes of the grid are > offset from the walls of the environment by an angle that minimizes > symmetry with the wall axes. The offset is always accompanied by an > elliptic distortion of the grid pattern. Offset and distortion can both be > removed by a shear transformation along one or several walls of the box, > pointing to shear forces from specific geometric references as elements of > the mechanism for anchoring grids to the external world. > > > > In the second part of the talk, we will focus on the mechanism by which > grid patterns are updated in accordance with the animal’s movement in the > environment. For grid cells to be updated efficiently, the cells need > information about the animal’s instantaneous running speed. We will show > that running speed is represented in the firing rate of a ubiquitous but > functionally dedicated population of neurons in the medial entorhinal > cortex. This entorhinal subpopulation is characterized by a positive, > linear response to running speed and low overlap with other entorhinal cell > types, such as grid, head direction and border cells. > > > > The final part of the talk will address the mechanisms by which grid cells > interact with place cells in the hippocampus. We will show that the > hippocampus receives inputs from a variety of functional cell types in the > medial entorhinal cortex, including grid cells and border cells. We will > also show that place cells in the CA1 of the hippocampus are part of a > prefrontal-thalamic-neural circuit for representation of routes through the > environment, where the nucleus reuniens links medial prefrontal cortex with > the hippocampus. The findings imply that space and spatial navigation > recruit widespread cortical circuits, with the thalamus operating as a key > node for long-range communication between cortical regions involved in > navigation. >

8 years, 12 months

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aspuru-list April 2015