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A Rotary Motor for Bacterial Gliding

March 31, 2015
Fig. 1

Fig 1: Evidence for a Rotary Motor [see A.Shrivastava, P. P. Lele, H.C. Berg, "A Rotary Motor Drives Flavobacterium Gliding," Current Biology 25 (2015)].

While probing the mystery of how some bacteria move across surfaces, Prof. Howard Berg and researchers in his group, Abhishek Shrivastava and Pushkar Lele, have discovered a kind of rotary motor in the bacterium Flavobacterium johnsoniae.

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Operation of a Broadband Visible-Wavelength Astro-Comb with a High- Resolution Astrophysical Spectrograph

March 20, 2015
Figure 3

Fig. 3. (a) Dimensions of tapered photonic crystal fiber (PCF, not to scale). A solid-core PCF is tapered to the desired size over a few millimeters, which gives an adiabatic transition between the transverse modes of the large and small fiber cores. (b) Optical micrograph of tapered PCF with a sealed end.

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Oscillation of the Velvet Worm Slime Jet by Passive Hydrodynamic Instability

March 18, 2015
Figure 2

Fig 2: Squirt system and papilla structure. [Reprinted under the terms of the Creative Commons Attribution License: A. Concha, P. Mellado, B. Morera-Brenes, C. Sampaio Costa, L Mahadevan & J. Monge-Nájera, "Oscillation of the velvet worm slime jet by passive hydrodynamic instability," Nature Communications 6: 6292 (17 March 2015) doi:10.1038/ncomms7292.]

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Cooper Pairing in Non-Fermi Liquids

March 6, 2015
Figure 1

Figure 1: Top: conventional phase diagram of a quantum critical point (QCP) associated with an order parameter ϕ, with a superconducting dome (SC) partially overlapping the quantum critical region of the "bare" QCP of a metal. Bottom: the phase diagram obtained in this paper, with the SC dome fully overlapping the incipient regime of incoherent fermionic quasiparticles, while the quantum critical ϕ fluctuations survive into higher temperatures in the normal state. [©2015 American Physical Society]

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Solid Friction between Soft Filaments

March 3, 2015
Figure 2

Figure 2: 1D–Frenkel–Kontorova model accounts for the essential features of interfilament sliding friction. [From A. Ward, et al., "Solid friction between soft filaments," Nature Materials (2015). Reprinted by permission from Macmillan Publishers Ltd: Nature Materials ©2015.]

Any macroscopic deformation of a filamentous bundle is necessarily accompanied by local sliding and/or stretching of the constituent filaments. Yet the nature of the sliding friction between two aligned filaments interacting through multiple contacts remains largely unexplored.

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