aspuru-list April 2013

aspuru-list@lists.fas.harvard.edu

54 participants
81 discussions

[Aspuru-Guzik group list] Applied Math Seminar Today

by Jarrod McClean

Applied math seminar which seems to creatively use compressive sensing with machine learning to characterize dynamics of systems. Could be of interest to some people in the group who look at compressive sensing, machine learning, dimensionality reduction or attractors/general chaos theory. Details below: Location/Time: Lyman 425, 3-4pm J. Nathan Kutz, University of Washington Title: Spatiotemporal encoding/decoding of nonlinear dynamics using compressive sensing and machine learning Abstract: Many high-dimensional complex systems often exhibit dynamics that evolve on a slow-manifold and/or a low-dimensional attractor. Thus we propose a data-driven modeling strategy that encodes/decodes the dynamical evolution using compressive (sparse) sensing (CS) in conjunction with machine learning (ML) strategies. $L^2$ based dimensionality reduction methods such as the proper orthogonal decomposition are used for constructing the machine-learned modal libraries ({\em encoding}) and sparse sensing is used to identify and reconstruct the low-dimensional manifolds ({\em decoding}). This technique provides an objective and general framework for characterizing the underlying dynamics, stability and bifurcations of complex systems. The integration of ML and CS techniques also provide an ideal basis for applying control algorithms to the underlying low-dimensinal dynamical systems. The algorithm works equally well with experimental data and/or in an equation-free context, for instance by using dynamic mode decomposition or equation-free modeling in place of POD-type reductions.

11 years

[Aspuru-Guzik group list] ITAMP topical lunch discussion: Thursday April 25 @ 12:00

by Mikhail Lemeshko

* Dear Friends, On Thursday, April 25, there will be an ITAMP topical lunch discussion. Tea Room (P-226) @ CfA (60 Garden Street) Time: 12:00-1:30 As always pizza will be served. Speaker: Prof. Maxim Olshanii (University of Massachusetts Boston) Title: Geometry of Quantum Observables, Integrability-Thermalizability Transition, and Extended Thermodynamics of Integrable and/or Mesoscopic Systems Abstract: The concept of ergodicity—convergence of the temporal averages of observables to their ensemble averages—is the cornerstone of thermodynamics. The transition from a predictable, integrable behavior to ergodicity is one of the most difficult physical phenomena to treat; the celebrated KAM theorem is the prime example. This preentation is founded on an observation that for many classical and quantum observables, the sum of the ensemble variance of the temporal average and the ensemble average of temporal variance remains approximately constant across the integrability-ergodicity transition. We show that this property induces a particular geometry of quantum observables—Frobenius or Hilbert-Schmidt one—that naturally encodes all the phenomena associated with the emergence of ergodicity: the Eigenstate Thermalization effect, decrease in the inverse participation ratio, and the disappearance of the integrals of motion. As an application, we use this geometry to solve a known problem of optimization of the set of integrals of motion needed to describe the steady state of an integrable or near-integrable system. Looking forward to seeing you there, Misha Lemeshko* -- Dr. Mikhail Lemeshko 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. mlemeshko(a)cfa.harvard.edu http://sites.google.com/site/mishalemeshko/ Tel. +1 (617) 496-7610 Fax +1 (617) 496-7668

11 years

[Aspuru-Guzik group list] Fwd: MOS Seminar, tomorrow (Tuesday), 12 pm

by Alan Aspuru-Guzik

-- Alan Aspuru-Guzik Professor of Chemistry and Chemical Biology Harvard University http://aspuru.chem.harvard.edu Forwarded message: > From: Gleb Akselrod <gleb.akselrod(a)gmail.com> > To: Gleb Akselrod <gleb.akselrod(a)gmail.com> > Date: Monday, April 22, 2013, 5:15:47 PM > Subject: MOS Seminar, tomorrow (Tuesday), 12 pm > > Hello colleagues, > I would like to invite you all to the Modern Optics and Spectroscopy Seminar, which I will be giving tomorrow (Tuesday) at 12 pm, in the Grier Room, 34-401. Hope you can come. > > Cheers, > Gleb > J-aggregates: Excitonic Material for Strong Light-Matter Coupling and Energy Funneling > Gleb M. Akselrod > Coherent coupling between chromophores is in part responsible for the remarkable energy transfer efficiency of natural photosynthetic systems. If Nature can do it, can we engineer materials with such coherent interactions that can be harnessed in optoelectronic devices ranging from lasers to solar cells to photodectectors? In this talk I will discuss my work on J-aggregates, a remarkable organic material made by the self-assembly of organic dye molecules into sheets. The result of this aggregation is a coherently delocalized exciton at room temperature with extremely high optical absorption and record exciton diffusion lengths (~100 nm). I will first show that these J-aggregate properties can be exploited in optical microcavities to obtain laser operation in the strong light-matter coupling regime. Second, I will demonstrate how J-aggregates can be used as an excitonic antenna for fluorescence enhancement of single molecules and quantum dots, an excitonic analogue to plasm onic enh ancement. > >

11 years

[Aspuru-Guzik group list] Excitonics Seminar - Graham Fleming - April 25, 3 pm, 36-428

by Catherine M Bourgeois

Please post and forward to your groups - Thanks. -------------------------------------- Center for Excitonics Seminar Series Thurs, April 25, 2013 3:00 PM RLE Haus Room: 36-428 EXCITATION ENERGY FLOW IN PHOTOSYNTHESIS Graham R Fleming, Dept. of Chemistry, U.C. Berkeley & Physical Biosciences Division, Lawrence Berkeley National Lab Abstract: The process of light harvesting in photosynthetic plants, algae and bacteria can involve the motion of excitation energy moving through hundreds, and in extreme cases, hundreds of thousands of optically active chromophores, typically chlorophylls and bacteriochlorophylls. Yet a static picture of the light harvesting system is far from a true picture. Light harvesting in plants and algae is highly regulated on a seconds-to-minutes timescale to avoid, for example, damage from excess solar illumination. At low light levels light harvesting transfers excitation energy to the chemically active reaction center with ~97% efficiency, at high light up to 80% of the absorbed photons are harmlessly degraded to heat before reaching the reaction center. These twin requirements mean that a system's model spans at least 14 orders of magnitude in time. In this talk I will discuss light harvesting over this range of time and length-scales from the single molecular complex to the photosystem II supercomplex with about 600 chlorophyll molecules. Bio: Graham Fleming earned his BS degree from the University of Bristol in 1971, and his Ph.D. in Chemistry from the University of London in 1974. Following a post-doctoral fellowship at the University of Melbourne, Australia, he joined the faculty of the University of Chicago in 1979. There, he was the Arthur Holly Compton Distinguished Service Professor for ten years, starting in 1987. He also served three years as Chair of the Chemistry Department where he led the creation of University of Chicago's Institute for Biophysical Dynamics. Fleming is currently the Vice Chancellor for Research at the University of California since 2009 and Professor of Chemistry at UC Berkeley, since 1997. Through high level positions at UC Berkeley and Lawrence Berkeley National Laboratory (where he was Deputy Laboratory Director from 2004 - 2006), he has been involved in the formation and operation of multiple major initiatives at Berkeley and LBNL. These include the $500M BP funded Energy Biosciences Institute, The California Institute for Quantitative Bioscience and the Simons Institute for the Theory of Computing. He has authored or co-authored more than 444 publications, and is widely considered to be one of the world's foremost authorities on ultrafast processes. His ultimate goal is to develop artificial photosynthesis that would provide humanity with clean, efficient and sustainable energy." Light refreshments will be served

11 years

[Aspuru-Guzik group list] Meeting with a postdoc interviewee

by Dmitry Zubarev

Dear Colleagues, Dr. Elton Santos (Kaxiras Group) will be visiting the Group for the interview on Thursday, March 14. Please let me know if you would like to meet with him for 20-30 minutes between 10 am and 1:15 pm. Also, I'm looking for 2-3 people to join us for lunch and a mutually enriching conversation from 1:30pm to 2:30 pm. The following link will give you a good idea about his area of expertise: http://scholar.google.com/citations?user=vNc3cXgAAAAJ Best, Dmitry

11 years

[Aspuru-Guzik group list] [theochem-announce] Lecture by Prof. Boris Shraiman

by Shane Yost

Hey everyone, This weeks theoretical chemistry seminar series on *Wednesday April 24th**at MIT in room 4-163 from 4:00 to 6:00 pm* will be given by Prof. Boris Shraiman from UC Santa Barbara. As normal for the theoretical chemistry seminar series there will be a brief break after one hour. The title of his talk is, "*Statistical Genetics and Dynamics of Natural Selection*." The abstract is: "This talk will review recent progress in understanding dynamics of natural selection under the conditions of high genetic diversity, focusing on the effects of interactions and seeking 'emergent simplicity' of the limit when fitness differentials are due to a large number of mutations each having only a small effect." - Shane Yost Van Voorhis Group MIT _______________________________________________ theochem-announce mailing list theochem-announce(a)mit.edu http://mailman.mit.edu/mailman/listinfo/theochem-announce

11 years

[Aspuru-Guzik group list] [qip] Toby Cubitt visit

by aram harrow

Dear quanta, Toby Cubitt (from U. Cambridge) is visiting this week and will be in room 6-414. He is giving the seminar on Friday, but don't wait until then to talk to him! His email address is tsc25(a)cam.ac.uk, and here are his papers http://arxiv.org/find/all/1/au:+Cubitt_T/0/1/0/all/0/1 -aram _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip

11 years

[Aspuru-Guzik group list] Seminar and group meeting cancelled

by Alan Aspuru-Guzik

Seminar and group meeting cancelled. Dear Group and Helen Stay home and not come to Harvard. The shooter is still at large. We are canceling our itamp seminar and group meeting. Have a nice weekend hopefully Alan -- Alan Aspuru-Guzik Associate Professor of Chemistry and Chemical Biology Harvard University http://aspuru.chem.harvard.edu Forwarded message: > From: Katie Lapp <evp(a)harvard.edu> > To: aspuru(a)chemistry.harvard.edu > Date: Friday, April 19, 2013, 6:45:42 AM > Subject: University closed > > If you are unable to see the message below, click here to view (http://links.mkt3495.com/servlet/MailView?ms=NDg3ODEwMwS2&r=MjE4MzYzNzA3MTI…). > Dear Harvard community members: > I trust that you have already received a Harvard Alert informing you that the University is closed due to the ongoing public safety situation in our area. > Law enforcement officials are searching a wide area not far from the Cambridge/Allston campus for an armed and dangerous suspect who they believe participated in the bombings at the Boston Marathon on Monday. Public transportation across Greater Boston has been suspended. > In consideration of the manhunt that is underway, we are asking members of the Harvard community to remain home from work and classes today. For personnel whose duties include health, safety or other critical operations, we ask that you check in with your supervisors to ensure that those functions can continue. > Similarly, the Harvard University Police Department is advising community members to stay indoors while the search for the suspect continues. > Please watch Harvard.edu for updates. > Sincerely, > Katie Lapp > Executive Vice President > > > > >

11 years

[Aspuru-Guzik group list] Fwd: MIT Shooting #8 issued at 4/19/13 5:52 AM

by Marlon Cummings

---------- Forwarded message ---------- From: "Harvard Alert" <17806787_1387757220(a)notify2.mir3.com> Date: Apr 19, 2013 6:01 AM Subject: MIT Shooting #8 issued at 4/19/13 5:52 AM To: <marlon_cummings(a)radcliffe.edu> HARVARD ALERT - The University is closed due to public safety concerns. Please watch Harvard.edu for updates.

11 years

[Aspuru-Guzik group list] News of interest to organic solar cell people

by Adrian Jinich

Pentacene.... http://web.mit.edu/newsoffice/2013/photon-to-electron-conversion-0418.html cheers, adrian

11 years

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aspuru-list April 2013