Publications

A. Banerjee, D. R. Vogus, T. M. Squires. "Design strategies for engineering soluto-inertial suspension interactions." Physical Review E, 100(5), 052603, 2019. DOI: 10.1103/PhysRevE.100.052603

I. Williams, J. A. Zasadzinski, T. M. Squires. "Interfacial rheology and direct imaging reveal domain-templated network formation in phospholipid monolayers penetrated by fibrinogen." Soft matter, 15, 9076-9084, 2019. DOI: 10.1039/C9SM01519A

A. Banerjee, T. M.Squires. "Long-range, selective, on-demand suspension interactions: Combining and triggering soluto-inertial beacons." Science advances, 5(8), eaax1893, 2019. DOI: 10.1126/sciadv.aax1893

C. C. Chang, I. Williams, A. Nowbahar, V. Mansard, J. Mecca, K. A. Whitaker, A. K. Schmitt, C. J. Tucker, T. H. Kalantar, T. C. Kuo, T. M. Squires. "Effect of Ethylcellulose on the Rheology and Mechanical Heterogeneity of Asphaltene Films at the Oil–Water Interface." Langmuir, 35(29), 9374-9381, 2019. DOI: 10.1021/acs.langmuir.9b00834

A. Nowbahar, A. O'Connor, V. Mansard, P. Spicer, T. M. Squires. "Salt comets in hand sanitizer: A simple probe of microgel collapse dynamics." Physical Review Fluids, 4(6), 061301, 2019. DOI: 10.1103/PhysRevFluids.4.061301

J. Song, M. Caggioni, T. M. Squires, J. F. Gilchrist, S. W. Prescott, P. T. Spicer. "Heterogeneity, suspension, and yielding in sparse microfibrous cellulose gels 2: strain rate-dependent two-fluid behavior." Rheologica Acta, 58(5), 231-239, 2019. DOI: 10.1007/s00397-019-01141-3

J. Song, M. Caggioni, T. M. Squires, J. F. Gilchrist, S. W. Prescott, P. T. Spicer. "Heterogeneity, suspension, and yielding in sparse microfibrous cellulose gels 1. Bubble rheometer studies." Rheologica Acta, 58(5), 217-229, 2019. DOI: 10.1007/s00397-019-01140-4

E. M. Furst, T. M. Squires. "Microrheology." Oxford University Press 

D. R. Vogus, M. A. Evans, A. Pusuluri, A. Barajas, M. Zhang, V. Krishnan, M. Nowak, S. Menegatti, M. E. Helgeson, T. M. Squires, S. Mitragotri. "A hyaluronic acid conjugate engineered to synergistically and sequentially deliver gemcitabine and doxorubicin to treat triple negative breast cancer." Journal of Controlled Release, 267, 191–202, 2017. DOI: 10.1016/j.jconrel.2017.08.016

T. M. Squires. "Micro-plumes for nano-velocimetry." Journal of Fluid Mechanics, 832, 1–4, 2017. DOI: 10.1017/jfm.2017.688

A. V. Bayles, T. M. Squires, M. E. Helgeson. "Probe microrheology without particle tracking by differential dynamic microscopy." Rheologica Acta, 56, 11, 863–869, 2017. DOI: 10.1007/s00397-017-1047-7

H. Manikantan, T. M. Squires. “Irreversible particle motion in surfactant-laden interfaces due to pressure-dependent surface viscosity.”  Proceedings of the Royal Society A, 473, 2205, 2017. DOI: 10.1098/rspa.2017.0346

R. Nery-Azevedo, A. Banerjee, T. M. Squires. "Diffusiophoresis in ionic surfactant gradients." Langmuir, 33, 38, 9694-9702. DOI: 10.1021/acs.langmuir.7b01094

H. Manikantan, T. M. Squires. “Pressure-dependent surface viscosity and its surprising consequences in interfacial lubrication flows.”  Physical Review Fluids, 2, 023301, 2017. DOI: 10.1103/PhysRevFluids.2.023301

A. K. Sachan, S. Q. Choi, K. H. Kim, Q. Tang, L. Hwang, K. Y. C. Lee, T. M. Squires, J. A. Zasadzinski. “Interfacial rheology of coexisting solid and fluid monolayers.” Soft Matter, 13, 1481-1492, 2017. DOI: 10.1039/C6SM02797K

C. Chang, A. Nowbahar, V. Mansard, I. Williams, J. Mecca, A. Schmitt, T. Kalantar, T. Kuo, T. M. Squires. "Interfacial Rheology and Heterogeneity of Aging Asphaltene Layers at the Water–Oil Interface." Langmuir, 34, 19, 5409-5415, 2018. DOI: 10.1021/acs.langmuir.8b00176

A. Nowbahar, V. Mansard, J. M. Mecca, M. Paul, T. Arrowood, T. M. Squires. "Measuring interfacial polymerization kinetics using microfluidic interferometry." J. Am. Chem. Soc, 140, 9, 2018, 3173-3176. DOI: 10.1021/jacs.7b12121

I. Williams, T. M. Squires. “Evolution and mechanics of mixed phospholipid fibrinogen monolayers.”  Journal of the Royal Society Interface, 15, 20170895, 2018. DOI: 10.1098/rsif.2017.0895

K. Kim, S. Q. Choi, J. A. Zasadzinski, T. M. Squires. “Nonlinear chiral rheology of phospholipid monolayers.”  Soft Matter, 14, 2476, 2018. DOI: 10.1039/C8SM00184G

S. Rezvani, N. Shi, T. M. Squires, C F. Schmidt. "Microfluidic device for chemical and mechanical manipulation of suspended cells." Journal of Physics D: Applied Physics, 51(4), 045403, 2018. DOI: 10.1088/1361-6463/aaa121

A. V. Bayles, C. S. Valentine, T. Überrück, S. P. O. Danielsen, S. Han, M. E. Helgeson, T. M. Squires. "Anomalous Solute Diffusivity in Ionic Liquids: Label-Free Visualization and Physical Origins." Physical Review X, 9(1), 011048, 2019. DOI: 10.1103/PhysRevX.9.011048

N. Shi, R. N. Azevedo, A. I. Abdel-Fattah, T. M. Squires. “Diffusiophoretic focusing of suspended colloids.”  Physical Review Letters, 117(25), 258001, 2016. DOI: 10.1103/PhysRevLett.117.258001

A. Banerjee, I. Williams, R. N. Azevedo, M. E. Helgeson, T. M. Squires. “Soluto-inertial phenomena: Designing long-range, long-lasting, surface-specific interactions in suspensions.”  Proceedings of the National Academy of Sciences, 113(31), 8612-8617, 2016. DOI: 10.1073/pnas.1604743113

G. J. Elfring, L. G. Leal, T. M. Squires. “Surface viscosity and Marangoni stresses at surfactant laden interfaces.”  Journal of Fluid Mechanics, 792, 712-739, 2016. DOI: 10.1017/jfm.2016.96

V. Mansard, J. M. Mecca, D. L. Dermody, D. Malotky, C. J. Tucker, T. M. Squires. “Collective Rayleigh-Plateau Instability: A Mimic of Droplet Breakup in High Internal Phase Emulsion.”  Langmuir, 32 (11), 2549-2555, 2016. DOI: 10.1021/acs.langmuir.5b04727

M. A. Brown, Z Abbas, A. Kleibert, R. G. Green, A. Goel, S. May, T. M. Squires. “Determination of Surface Potential and Electrical Double-Layer Structure at the Aqueous Electrolyte-Nanoparticle Interface.”  Physical Review X, 6, 011007, 2016. DOI: 10.1103/PhysRevX.6.011007

M. Rey, M. A. Fernandez-Rodriguez, M. Steinacher, L. Scheidegger, K. Geisel, W. Richtering, T. M. Squires, L. Isa. “Isostructural solid–solid phase transition in monolayers of soft core–shell particles at fluid interfaces: structure and mechanics.”  Soft Matter, 12, 3545-3557, 2016. DOI: 10.1039/C5SM03062E

Z. A. Zell, V. Mansard, J. Wright, K. H. Kim, S. Q. Choi, T. M. Squires. “Linear and nonlinear microrheometry of small samples and interfaces using microfabricated probes.”  Journal of Rheology, 60 (1), 141-159, 2016. DOI: 10.1122/1.4937931

A. V. Bayles, T. M. Squires, M. E. Helgeson. “Dark-field differential dynamic microscopy.”  Soft Matter, 12, 2440-2452, 2016. DOI: 10.1039/C5SM02576A

J. S. Paustian, C. D. Angulo, R. Nery-Azevedo, N. Shi, A. I. Abdel-Fattah, T. M. Squires. “Direct measurements of colloidal solvophoresis under imposed solvent and solute gradients.” Langmuir, 31, 4402-4410, 2015. DOI:10.1021/acs.langmuir.5b00300

B. Giera, N. Henson, E. M. Kober, M. S. Shell, T. M. Squires. “Electric double-layer structure in primitive model electrolytes: comparing molecular dynamics with local-density approximations.” Langmuir, 31, 3553-3562, 2015. DOI: 10.1021/la5048936

I. Buttinoni, Z. A. Zell, T. M. Squires, L. Isa. "Colloidal binary mixtures at fluid-fluid interfaces under steady shear: structural, dynamical and mechanical response."  Soft Matter, 11 (42), 8313-8321, 2015.  DOI: 10.1039/C5SM01693B

D. R. Vogus, V. Mansard, M. Rapp, T. M. Squires. “Measuring concentration fields in microfluidic channels in situ with a Fabry-Perot interferometer.” Lab. Chip, 15, 1689-1696, 2015. DOI: 10.1039/C5LC00095E

M. Mirzadeh, F. Gibou, T. M. Squires. “Enhanced charging kinetics of porous electrodes: Surface conduction as a short-circuit mechanism.”  Physical Review Letters, 113 (9), 097701, 2014. DOI: 10.1103/PhysRevLett.113.097701

S. Q. Choi, K. Kim, C. M. Fellows, K. D. Cao, B. Lin, K. Y. C. Lee, T. M. Squires, J. A. Zasadzinski. “Influence of molecular coherence on surface viscosity.”  Langmuir, 30 (29), 8829-8838, 2014. DOI: 10.1021/la501615g

Y. Komoda, L. G. Leal, T. M. Squires. “Local, real-time measurement of drying films of aqueous polymer solutions using active microrheology.”  Langmuir, 30 (18), 5230-5237, 2014. DOI: 10.1021/la5001733

T. M. Squires. “Cross‐stream migration vs. anisotropic relaxation: Non‐Boltzmann distributions in dissipative systems.”  AIChE Journal, 60 (4), 1434-1450, 2014. DOI: 10.1002/aic.14408

Z. A. Zell, A. Nowbahar, V. Mansard, L. G. Leal, S. S. Deshmukh, J.M. Mecca, C. J. Tucker, T. M. Squires. “Surface shear inviscidity of soluble surfactants.”  Proceedings of the National Academy of Sciences, 111 (10), 3677-3682, 2014. DOI: 10.1073/pnas.1315991111

A. C. Anselmo, C. L. Modery-Pawlowski, S. Menegatti, S. Kumar, D. R. Vogus, L. L. Tian, M. Chen, T. M. Squires, A. S. Gupta, S. Mitragotri. “Platelet-like Nanoparticles: Mimicking Shape, Flexibility, and Surface Biology of Platelets To Target Vascular Injuries.”  ACS Nano, 8, 11243-11253, 2014. DOI: 10.1021/nn503732m

J. S. Paustian, A. J. Pascall, N. M. Wilson, T. M. Squires. “Induced charge electroosmosis micropumps using arrays of Janus micropillars.”  Lab on a Chip, 14 (17), 3300-3312, 2014. DOI: 10.1039/C4LC00141A

Z. A. Zell, L. Isa, P. Ilg, L. G. Leal, T. M. Squires. “Induced charge electroosmosis micropumps using arrays of Janus micropillars.”  Langmuir, 30 (1), 110-119, 2013. DOI: 10.1021/la404233a

J. S. Paustian, R. N. Azevedo, S. T. B. Lundin, M. J. Gilkey, T. M. Squires. “Microfluidic microdialysis: Spatiotemporal control over solution microenvironments using integrated hydrogel membrane microwindows.”  Physical Review X, 3 (4), 041010, 2013. DOI: 10.1103/PhysRevX.3.041010

K. H. Kim, S. Q. Choi, Z. A. Zell, T. M. Squires, J. A. Zasadzinski. “Effect of cholesterol nanodomains on monolayer morphology and dynamics.”  Proceedings of the National Academy of Sciences, 110 (33), E3054-E3060, 2013. DOI: 10.1073/pnas.1303304110

T. M. Squires. “Drops on soft surfaces learn the hard way.”   Proceedings of the National Academy of Sciences , 110 (31), 12505-12506, 2013. DOI: 10.1073/pnas.1310672110

B. Giera, N. Henson, E. M. Kober, T. M. Squires, M. S. Shell. “Model-free test of local-density mean-field behavior in electric double layers.”   Physical Review E, 88 (1), 011301, 2013. DOI: 10.1103/PhysRevE.88.011301

R. J. DePuit T. M. Squires. “Micro–macro-discrepancies in nonlinear microrheology: I. Quantifying mechanisms in a suspension of Brownian ellipsoids.”  Journal of Physics: Condensed Matter, 24 (46), 464106, 2012. DOI: 10.1088/0953-8984/24/46/464106

R. J. DePuit T. M. Squires. “Micro–macro discrepancies in nonlinear microrheology: II. Effect of probe shape.”  Journal of Physics: Condensed Matter, 24 (46), 464107, 2012. DOI: 10.1088/0953-8984/24/46/464107

A. Colin, T. M. Squires, L. Bocquet. “Soft matter principles of microfluidics.”  Soft Matter, 8 (41), 10527-10529, 2012. DOI: 10.1039/C2SM90116A

M. R. Leyden, R. J. Messinger, C. Schuman, T. Sharf, V. T. Remcho, T. M. Squires, E. D. Minot. “Increasing the detection speed of an all-electronic real-time biosensor.”  Lab on a Chip, 12 (5), 954-959, 2012. DOI: 10.1039/C2LC21020G

A. J. Pascall,T. M. Squires. “Electrokinetics at liquid/liquid interfaces.”  Journal of Fluid Mechanics, 684, 163-191, 2011. DOI: 10.1017/jfm.2011.288

R. J. DePuit, A. S. Khair, T. M. Squires. “A theoretical bridge between linear and nonlinear microrheology.”  Physics of Fluids, 23 (6), 063102, 2011. DOI: 10.1063/1.3598322

S. Q. Choi, S. G. Jang, A. J. Pascall, M. D. Dimitriou, T. Kang, C. J. Hawker, T. M. Squires. “Synthesis of Multifunctional Micrometer-Sized Particles with Magnetic, Amphiphilic, and Anisotropic Properties.”  Advanced Materials, 23 (20), 2348-2352, 2011. DOI: 10.1002/adma.201003604

S. Q. Choi, S. Steltenkamp, J. A. Zasadzinski, T. M. Squires. “Active microrheology and simultaneous visualization of sheared phospholipid monolayers.”  Nature communications, 2, 312, 2011. DOI: 10.1038/ncomms1321

K. H. Kim, S. Q. Choi, J. A. Zasadzinski, T. M. Squires. “Interfacial microrheology of DPPC monolayers at the air–water interface.”  Soft Matter, 7 (17), 7782-7789, 2011. DOI: 10.1039/C1SM05383C

T. M. Squires, T. G. Mason. “Tensorial generalized Stokes–Einstein relation for anisotropic probe microrheology.”  Rheologica acta, 49 (11-12), 1165-1177, 2010. DOI: 10.1007/s00397-010-0490-5

A. S. Khair, T. M. Squires. “Active microrheology: A proposed technique to measure normal stress coefficients of complex fluids.”  Physical Review Letters, 105 (15), 156001, 2010. DOI: 10.1103/PhysRevLett.105.156001

R. J. Messinger, T. M. Squires. “Suppression of electro-osmotic flow by surface roughness.”   Physical Review Letters, 105 (14), 144503, 2010. DOI: 10.1103/PhysRevLett.105.144503

Z. A. Zell, S. Y. Q. Choi, 최시영, L. G. Leal, T. M. Squires. “Microfabricated deflection tensiometers for insoluble surfactants.”  Applied Physics Letters, 97 (13), 133505, 2010. DOI: 10.1063/1.3491549

S. Y. Q. Choi, T. M. Squires. “Dynamics within surfactant monolayers.”  Physics of Fluids, 22 (9), 091113, 2010. DOI: 10.1063/1.3492833

M. Z. Bazant, T. M. Squires. “Induced-charge electrokinetic phenomena.”  Current Opinion in Colloid & Interface Science, 15 (3), 203-213, 2010. DOI: 10.1016/j.cocis.2010.01.003

T. M. Squires. “A furtive stare at an intra-cellular flow.”  Journal of Fluid Mechanics, 642, 1-4, 2010. DOI: 10.1017/S0022112009992990

A. J. Pascall, T. M. Squires. “An automated, high-throughput experimental system for induced charge electrokinetics.”  Lab on a Chip, 10(18), 2350-2357, 2010. DOI: 10.1039/C004926C

T. M. Squires, T. G. Mason. “Fluid mechanics of microrheology.”  Annual review of fluid mechanics, 42, 413-438, 2010. DOI: 10.1146/annurev-fluid-121108-145608

A. S. Khair, T. M. Squires. “Ion steric effects on electrophoresis of a colloidal particle.”  Journal of Fluid Mechanics, 640, 343-356, 2009. DOI: 10.1017/S0022112009991728

T. S. Mansuripur, A. J. Pascall, T. M. Squires. “IAsymmetric flows over symmetric surfaces: capacitive coupling in induced-charge electro-osmosis.”  New Journal of Physics, 11 (7), 075030, 2009. DOI: 10.1088/1367-2630/11/7/075030

A. S. Khair, T. M. Squires. “The influence of hydrodynamic slip on the electrophoretic mobility of a spherical colloidal particle.”  Physics of Fluids, 21 (4), 042001, 2009. DOI: 10.1063/1.3116664

I. Sriram, E. M. Furst, R. J. DePuit, T. M. Squires. “Small amplitude active oscillatory microrheology of a colloidal suspension.”  Journal of Rheology, 53 (2), 357-381, 2009. DOI: 10.1122/1.3058438

T. M. Squires. “Induced-charge electrokinetics: fundamental challenges and opportunities.”  Lab on a Chip, 9 (17), 2477-2483, 2009. DOI: 10.1039/B906909G

A. S. Khair, T. M. Squires. “Surprising consequences of ion conservation in electro-osmosis over a surface charge discontinuity.”  Journal of Fluid Mechanics, 615, 323-334, 2008. DOI: 10.1017/S002211200800390X

T. M. Squires. “The inner life of mesoorganisms.”  Physics, 1, 30, 2008. DOI:

M. Roper, T. M. Squires, M. P. Brenner. “Symmetry unbreaking in the shapes of perfect projectiles.”  Physics of Fluids, 20 (9), 093606, 2008. DOI: 10.1063/1.2982500

T. M. Squires. “Electrokinetic flows over inhomogeneously slipping surfaces.”  Physics of Fluids, 20 (9), 092105, 2008. DOI: 10.1063/1.2978954

A. S. Khair, T. M. Squires. “Fundamental aspects of concentration polarization arising from nonuniform electrokinetic transport.”  Physics of Fluids, 20 (8), 087102, 2008. DOI: 10.1063/1.2963507

T. M. Squires, R. J. Messinger, S. R. Manalis. “Making it stick: convection, reaction and diffusion in surface-based biosensors.”  Nature biotechnology, 26 (4), 417-426, 2008. DOI: 10.1038/nbt1388

T. M. Squires. “Nonlinear microrheology: Bulk stresses versus direct interactions.”  Langmuir, 24 (4), 1147-1159, 2008. DOI: 10.1021/la7023692

M. Narovlyansky, G. M. Whitesides, T. M. Squires. “Zone sculpting using partitioned electrokinetic injections.”  Applied Physics Letters, 91 (20), 203511, 2007.  DOI: 10.1063/1.2814031

M. M. Denn, E. H. Meiburg, J. F. Morris, E. S. G. Shaqfeh, T. M. Squires. “Report of the Symposium on Interactions for Dispersed Systems in Newtonian and Viscoelastic Fluids, Guanajuato, Mexico, 2006.”  Physics of Fluids, 18 (12), 121501, 2006. DOI: 10.1063/1.2396902

T. M. Squires, M. Z. Bazant. “Breaking symmetries in induced-charge electro-osmosis and electrophoresis.”  Journal of Fluid Mechanics, 560, 65-101, 2006. DOI: 10.1017/S0022112006000371

T. M. Squires, S.R. Quake. “Microfluidics: Fluid physics at the nanoliter scale.”  Reviews of modern physics, 77 (3), 977, 2005.  DOI: 10.1103/RevModPhys.77.977

J. A. Levitan, S. Devasenathipathy, V. Studer, Y. Ben, T. Thorsen, T. M. Squires. “Experimental observation of induced-charge electro-osmosis around a metal wire in a microchannel.”  Colloids and Surfaces A: Physicochemical and Engineering Aspects, 267 (1), 122-132, 2005.  DOI: 10.1016/j.colsurfa.2005.06.050

E. Lauga, T. M. Squires. “Brownian motion near a partial-slip boundary: A local probe of the no-slip condition.”  Physics of Fluids, 17 (10), 103102, 2005.  DOI: 10.1063/1.2083748

J. Choi, D. Margetis, T. M. Squires, M. Z. Bazant. “Steady advection–diffusion around finite absorbers in two-dimensional potential flows.”  Journal of Fluid Mechanics, 536, 155-184, 2005.  DOI: 10.1017/S0022112005005008

T. M. Squires, J. F. Brady. “A simple paradigm for active and nonlinear microrheology.”  Physics of Fluids, 17 (7), 073101, 2005.  DOI: 10.1017/S0022112005005008

T. C. Hain, T. M. Squires, H. A. Stone. “Clinical implications of a mathematical model of benign paroxysmal positional vertigo.”  Annals of the New York Academy of Sciences, 1039 (1), 384-394, 2005.  DOI: 10.1196/annals.1325.036

P. K. Purohit, M. M. Inamdar, P. D. Grayson, T. M. Squires, J. Kondev, R. Phillips. “Forces during bacteriophage DNA packaging and ejection.”  Biophysical Journal, 88 (20, 851-866, 2007.  DOI: 110.1529/biophysj.104.047134

T. M. Squires. “Optimizing the vertebrate vestibular semicircular canal: Could we balance any better?”  Physical Review Letters, 93 (19), 198106, 2004.  DOI: 10.1103/PhysRevLett.93.198106

T. M. Squires, M. S. Weidman, T. C. Hain, H. A. Stone. “A mathematical model for top-shelf vertigo: the role of sedimenting otoconia in BPPV.”  Journal of Biomechanics, 37 (8), 1137-1146, 2004.  DOI: 10.1016/j.jbiomech.2003.12.014

T. M. Squires, M. Z. Bazant. “Induced-charge electro-osmosis.”  Journal of Fluid Mechanics, 509, 217-252, 2004.  DOI: 10.1017/S0022112004009309

M. Z. Bazant, T. M. Squires. “Induced-charge electrokinetic phenomena: theory and microfluidic applications.”  Physical Review Letters, 92 (6), 066101, 2004.  DOI: 10.1103/PhysRevLett.92.066101

T. M. Squires, P. Yesley, G. Gabrielse. "Stability of a Charged Particle in a Combined Penning-Ioffe Trap." Physical Review Letters 86 (23), 2003. 10.1103/PhysRevLett.86.5266

G. Gabrielse, J. N. Tan, N. S. Bowden, P. Oxley, C. H. Storry, M. Wessels, A. Speck, J. Estrada, P. Yesley, T. M. Squires, D. Grzonka, W. Oelert, G. Schepers, T. Sefzick, J. Walz. "Cold antimatter plasmas, and aspirations for cold antihydrogen." AIP Conference Proceedings, 606 (1), 51-62, 2002. DOI: 10.1063/1.1454267

T. M. Squires. “Effective pseudo-potentials of hydrodynamic origin.”  Journal of Fluid Mechanics, 443, 403-412, 2001. DOI: 10.1017/S0022112001005432

T. M. Squires, P. Yesley, G. Gabrielse. “Stability of a charged particle in a combined Penning-Ioffe trap.”  Physical Review Letters, 86 (23), 5266, 2001. DOI: 10.1103/PhysRevLett.86.5266

T. M. Squires, M. P. Brenner. “Like-charge attraction and hydrodynamic interaction.”  Physical Review Letters, 85 (23), 4976, 2000.  DOI: 10.1103/PhysRevLett.85.4976

E. R. Dufresne, T. M. Squires, M. P. Brenner, D. G. Grier. “Hydrodynamic coupling of two Brownian spheres to a planar surface.”  Physical Review Letters, 85 (15), 3317, 2000.  DOI: 10.1103/PhysRevLett.85.3317