Events

  • Condensed Matter Seminar: "Enhanced optical and magnetic microscopy by orientation-dependent modulation of single-molecule and nitrogen-vacancy-center emission"

    David Rittenhouse Laboratory, A4

    Mikael Backlund (Harvard University)

    Selection rules impose geometrical constraints on the interactions of light and matter. In
    particular, an emitter with a well-defined orientation will emit photons of a characteristic
    polarization and wavevector distribution, even as viewed in the far field. Knowledge of these
    distributions can be leveraged to enhance a number of state-of-the-art microscopy techniques. In
    the first part of the talk I will discuss such an approach to single-molecule localization
    microscopy, relevant for single-molecule tracking and super-resolution imaging. It is known that

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  • Condensed Matter Seminar: "Structure and Topology of Band Structures in the 1651 Magnetic Space Groups"

    David Rittenhouse Laboratory, A4

    Ashvin Vishwanath (Harvard University)

    We describe a powerful theoretical approach to studying electronic band structures, which associates them with elements of a vector space. The set of consistent band structures in a space group can then be expanded in terms of a small set of basis vectors. We calculate the dimension of this vector space, and the necessary electron fillings to obtain band insulators in all magnetic space groups.

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  • Condensed Matter Seminar: "Geometry and mechanics of feet and fins"

    David Rittenhouse Laboratory, A4

    Mahesh M. Bandi (Okinawa Institute of Science and Technology Graduate University)

    The stiffness of propulsive appendages, such as feet and fins, is important in locomotory function. In this talk, I show that curvature-induced stiffness is the common principle underlying the stiffness of both primate feet and rayed fish fins. We use mathematical models, physical models, and biological experiments to arrive at this conclusion. The principle is evident in a drooping dollar bill that significantly stiffens upon slightly curling it in the transverse direction.

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  • Condensed Matter Seminar: "Ideas on magma motion within the lithosphere: percolation, channelization, and stress-driven segregation"

    David Rittenhouse Laboratory, A4

    Mousoumi Roy (University of New Mexico)

    Although we know that magma is generated by partial melting of rocks at depth, we have less of an understanding of the processes that transport magma from great depths (>100-150 km) into the shallower (20-0 km) crustal plumbing systems of volcanic zones.   I shall discuss how interstitial melt migrates via percolative flow, and ideas on how it eventually becomes focused and reorganized into networks.  Field and geochemical observations suggest that these networks are characterized by thermal and chemical disequilibrium between the magma and surrounding rock.  I

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  • Condensed Matter Seminar: "Programming shape"

    David Rittenhouse Laboratory, A4

    Lakshminarayanan Mahadevan (Harvard University)

    I will describe a few inverse problems in physical geometry, along with some (partial) solutions. These include  using kirigami to morph planar domains, using cylinders and spherical caps to create mechanical memories, using smooth growth patterns to create flowers and faces, and using origami to fold flat sheets into curved surfaces.

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  • Condensed Matter Seminar: "TBA"

    David Rittenhouse Laboratory, A4

    Harald Hess (Howard Hughes Medical Institute, Janelia Research Campus)

  • Condensed Matter Seminar: "The physical chemistry of natural selection: How can we explain the high yields and high rates of biochemical reactions?"

    David Rittenhouse Laboratory, A4

    Jean-Louis Sikorav (Ministère de l'Economie et des Finances)