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All-Optical Electrophysiology in Mammalian Neurons Using Engineered Microbial Rhodopsins

July 15, 2014

Optopatch enables high-fidelity optical stimulation and recording in cultured neurons: Parallel optical recording under increasingly strong 0.5-s optical step stimuli. Asterisk indicates a cell that showed periodic bursts of three or four APs under weak stimulation. Scale bar, 500 μm. Image is of EGFP fluorescence. [Figure reprinted by permission from Macmillan Publishers Ltd: see D.R. Hochbaum, Y. Zhao, S.L. Farhi, N. Klapoetke...

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Patterns Formed by Shadows of Spheres

July 6, 2014
Patterns Formed by Shadows of Spheres

Phase diagrams obtained via black CM2 1⁄4 0 and yellow CM3 1⁄4 0 curves for shadow overlap with nearest and next-nearest neighbors. Top left panel: Close-packed square lattice phase diagram (2r=a 1⁄4 2r=b 1⁄4 1, γ 1⁄4 π=2) reflects the fourfold lattice symmetry. Bottom left panel: Dense hexagonal lattice phase diagram (2r=a 1⁄4 2r=b 1⁄4 0.95, γ 1⁄4 π=3) with sixfold symmetry. [From S.V. Kostinski, E.R. Chen, and M.P. Brenner, "Characterization of Patterns Formed by Shadows of Spheres," Phys. Rev.

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Jerison, Chowdhury, Saklayen Win Fellowships

June 26, 2014
fellowships winners

Congratulations to Harvard Physics graduate students Elizabeth Jerison and Debanjan Chowdhury who won the Harvard Merit Scholarship and Nabiha Saklayen who was awarded an International Student Research Fellowship by the Howard Hughes Medical Institute.

The Harvard Merit/Term Time Research Awards are available to outstanding GSAS students in all fields. These fellowships are normally to be held in the fourth or fifth year, or earlier, and are for the purpose of allowing the students to devote a greater portion of their time to research, fieldwork, and writing than would otherwise be possible if they have a heavy teaching load or other employment.

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A Quantum Network of Clocks

June 16, 2014
World-wide quantum clock network

The concept of world-wide quantum clock network: Illustration of a cooperative clock operation protocol in which individual parties (for example, satellite-based atomic clocks from different countries) jointly allocate their respective resources in a global network involving entangled quantum states. This guarantees an optimal use of the global resources, achieving an ultra-precise clock signal limited only by the fundamental bounds of quantum metrology and, in addition, guaranteeing secure distribution of the clock signal. b. [Figure reprinted by permission from Macmillan Publishers Ltd: P. Kómár, E. M. Kessler, M. Bishof, L.

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Two Steps Forward, One Step Back

June 12, 2014

The rich get richer: Gain (purple points) and loss (yellow points) as a function of pre-test score. The more prior knowledge students have, the more concepts they gain during their course of study and the fewer they lose. [Figure reprinted by permission from Macmillan Publishers Ltd: N. Lasry, J. Guillemette, E. Mazur, "Two steps forward, one step back," Nature Physics 10, 402–403(2014) | doi:10.1038/nphys2988 ©2014.]

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The Dynamics of Quantum Criticality Revealed by Quantum Monte Carlo and Holography

June 12, 2014
Figure 4: Holographic continuation

Holographic continuation: a, The black points represent Monte Carlo data for the conductivity at the superfluid–insulator QCP at imaginary frequencies. b, Real part of the holographic conductivity evaluated at complex frequencies, where the imaginary/real axis dependence is highlighted by the green/blue line. The arrow represents the continuation procedure. c, Resulting conductivity at real frequencies (solid blue line). The dashed line is the vortex-like response obtained for γ =−0.08. [Figure reprinted by permission from Macmillan Publishers Ltd: W. Witczak-Krempa, E.S. Sørensen, S.

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Electron-Hole Asymmetric Integer and Fractional Quantum Hall Effect in Bilayer Graphene

June 5, 2014
Fractional quantum Hall states in bilayer graphene

Fractional quantum Hall states in bilayer graphene: (A and C) Inverse compressibility as a function of filling factor and magnetic field. The color scales are the same in both panels. (B and D) Average inverse compressibility between B = 7.9 and 11.9 T as a function of filling factor. Colors indicate regions of similar behavior in the background inverse compressibility. (E and F) Inverse compressibility as a function of filling factor and magnetic field near ν = 7/5 and 3/5.

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