• [picture]

    When experiments seem to imply that the stiffness of DNA depends on its length, what's really going on?
    Elasticity of short DNA molecules: Theory and experiment for contour lengths of 0.6--7 um. With Seol, Li, Perkins, and Betterton. Biophys. J. 93 4360 (2007).

  • [picture]

    How accurately can we infer the length of a long molecule from the motion of a bead on its end?
    Colloidal Particle Motion as a Diagnostic of DNA Conformational Transitions. Current Opinion in Colloid and Interface Science 12 307 (2007).

  • [picture]

    Are there long-lived kinetic substates in DNA looping?
    Diffusive hidden Markov model characterization of DNA looping dynamics in tethered particle experiments . With Beausang. Physical Biology 4 205 (2007).

  • [picture]

    How can you extract kinetics from noisy data without binning?
    DNA looping kinetics analyzed using diffusive hidden Markov model . With Beausang, Zurla, Manzo, Dunlap, and Finzi. Biophys. J. 92, L64 (2007).

  • [picture]

    Are there hidden regularities in "random" Brownian motion?
    Elementary simulation of tethered Brownian motion. With Beausang, Zurla, Sullivan, and Finzi. Am. J. Phys. 75, 520 (2007).

  • [picture]

    What energy source squirts viral DNA into a host cell?
    Biological Consequences of Tightly Bent DNA: The Other Life of a Macromolecular Celebrity . With Garcia, Grayson, Han, Inamdar, Kondev, Phillips, Widom, and Wiggins. Biopolymers 85, 115 (2007).

  • [picture]

    If DNA is a stiff elastic rod, how can it form those tight regulatory loops?
    High flexibility of DNA on short length scales probed by atomic force microscopy. With Wiggins, van der Heijden, Moreno-Herrero, Spakowitz, Phillips, Widom, and Dekker.Nature Nanotechnology 1, 137 (2006) A commentary appears here.
    See the Erratum to this article.

  • [picture]

    Do cells transport vesicles using active conveyor belts?
    Hitchhiking Through the Cytoplasm. With Kulic. Europhys. Lett. 81, 18001-(1--6) (2008).

  • [picture]

    How can you see protein binding in real time?
    Entropic elasticity of DNA with a permanent kink. With Betterton and Li. Macromolecules 39 8816 (2006).

  • [picture]

    When you twist a string, how does that affect loop formation?
    Effect of supercoiling on formation of protein mediated DNA loops. With Purohit. Phys. Rev. E74, art. no. 061907 (14 pages) (2006).
    See the Erratum to this article.

  • [picture]

    How can you detect DNA looping in real time, when you can't even see DNA?
    Tethered particle motion as a diagnostic of DNA tether length. With Zurla, Brogioli, Beausang, Finzi, and Dunlap. Journal of Physical Chemistry B110, 17260 (2006).

  • [picture]

    How can fluorescence tell us about molecular mechanics?
    Generalized theory of semiflexible polymers. With Wiggins. Phys. Rev. E73, art. number 031906 (2006).

  • [picture]

    What can a balloon in a hurricane tell us about gene regulation?
    Excluded-Volume Effects in Tethered-Particle Experiments: Bead Size Matters. With Segall and Phillips. Phys. Rev. Lett. 96 art. number 088306 (2006).

  • [picture]

    How does DNA spontaneously form gene regulatory complexes with "impossibly" tight loops?
    Exact theory of kinkable elastic polymers . With Wiggins and Phillips. Phys. Rev. E71 art. number 021909 (2005).

  • [picture]

    Is single-stranded DNA really a freely jointed chain?
    Theory of High-Force DNA Stretching and Overstretching. With Storm. Phys. Rev. E67 (2003) art. number 051906 (Erratum ibid. 70, 013902 (2004)).

  • [picture]

    What's going on when DNA stretches to 1.6 times its "maximum" length?
    The bend stiffness of S-DNA. With Storm. Europhys. Lett. 62 (2003) 760.

  • When will a plus act like a minus?
    Charge-Reversal Instability in Mixed Bilayer Vesicles. With Chen. Phys. Rev. E62 (2000) 2608.
    [picture]

    [picture] How can spheres self-assemble into platelets?
    Surfactant-mediated two-dimensional crystallization of colloidal crystals. With Ramos, Lubensky, Dan, Weitz. Science 286 (1999) 2325

    How can oppositely-charged objects repel?
    Electrostatic Repulsion of Positively Charged Vesicles and Negatively Charged Objects. With Aranda-Espinoza, Chen, Dan, Lubensky, Ramos, Weitz. Science 285 (1999) 394
    [picture]

    How can the activity of one gene activate another gene?
    Transport of Torsional Stress in DNA PNAS 96 (1999) 14342. (gzipped .ps)

    What can you learn by pulling on a mile-long rope in a hurricane?
    Entropic Elasticity of Twist-Storing Polymers. With Moroz. (Revised version.) Macromolecules 31 (1998) 6333 (gzipped .ps) [see Physics News Update]
    [picture]


    How does the information content of DNA show up in its mechanical properties?
    Sequence-Disorder Effects on DNA Entropic Elasticity Phys. Rev. Lett. 80 (1998) 5810.

    What happens when you tweak biomembranes using the world's smallest, most delicate tweezers?
    Dynamic Excitations in Membranes Induced by Optical Tweezers. With Bar-Ziv and Moses. (Biophys. J. 75 (1998) 294-320) (write me for a hard copy).
    [picture]

    [picture] What do you do when you need a nanoscale torque wrench?
    Torsional Directed Walks, Entropic Elasticity, and DNA Twist Stiffness. With Moroz. PNAS 94 (1997) 14418.
    Conference talks: Joint DIMACS/PMMB/MBBC Workshop on DNA Topology, Rutgers University (3--4 April 1997) (Biophys. J., 74 (1998) 2501); Condensed Matter Gordon Conference, July 1997.

    How can entropy make things more ordered?
    Hard Spheres in Vesicles: Curvature-Induced Forces and Particle-Induced Curvature. With Dinsmore, Wong, and Yodh. Phys. Rev. Lett. 80 (1998) 409(compressed .ps only)
    [picture]

    [picture] How can you detect the helical structure of DNA from its mechanical properties?
    Direct Determination of DNA Twist-Stretch Coupling. With Kamien, Lubensky, and O'Hern. Europhys. Lett 38 (1997) 237. (compressed version)

    Why would a large hole in a biomembrane stay open a long time, then snap shut suddenly?
    Dynamically-Stabilized Pores in Bilayer Membranes . With Moroz. Biophys. J. 72 (1997) 2211.
    [picture]

    [picture] How can a laser induce controlled membrane topology change (see the movie)?
    Spontaneous expulsion of giant lipid vesicles induced by laser tweezers. With Bar-Ziv, Moroz, and Moses. Phys. Rev. Lett. 78 (1997) 386. (compressed version) [see Physics News Update]

    What happens when you pull a tangled thread in honey?
    Straightening of Thermal Fluctuations in Semi-Flexible Polymers by Applied Tension. With Seifert and Wintz. Phys. Rev. Lett. 77 (1996) 5389. (compressed version)
    [picture]

    [picture] If membrane elasticity is really scale-invariant, then what could set the cell size of giant cubic phases?
    The Role of Bilayer Tilt Difference in Equilibrium Membrane Shapes. With Seifert and Shillcock. Phys. Rev. Lett. 77 (1996) 5237. (compressed version)

    How do you turn a blob of fat into a string of pearls (see the movie)? pearling graphic[picture]
    Front Propagation in the Pearling Instability of Tubular Vesicles. With Goldstein, Powers, Seifert. J. Phys. II (Paris) 6 (1996) 767. (compressed version)
    Dynamic Theory of Pearling Instability in Cylindrical Vesicles. With Powers and Seifert. Phys. Rev. Lett. 74 (1995) 3384. (compressed version)

    Why do helical membrane structures disappear right at the chain-melting transition?
    Fluctuating membranes with tilt order. With Powers. J. Phys. II (Paris) 5 (1995) 1671. (compressed version)