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Patricia Elizabeth Cladis

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Liquid crystals are condensed matter phases that show characteristics of both liquids and solids. They exhibit the fluidity of liquids and some of the long-range order of crystals. One phase, nematic, has long-range order in the orientation of rod-like molecules but not in their position. Smectic phases add positional order along one spatial direction.

The field of liquid crystals was rapidly advancing and headed for important technological applications at the time Dr. Cladis began her work. She made numerous experimental and theoretical contributions which were important for the understanding of the basic physics of liquid crystals and their technological applications.

Professor W. Gilbert Clark

• "Non-singular disclinations of strength S=+1 in nematics." J. de Physique 33:591 (1972) with M. Kléman.

Demonstration that a non-linear ordinary differential equation had standing soliton solutions that broke the symmetry of the boundary conditions. This equation has an infinite number of standing soliton solutions; the minimum energy one is called "escape into the third dimension". Subsequent work relates to how these other solutions can be accessed by systems out of equilibrium.

• "New liquid-crystal phase diagram," Phys. Rev. Lett. 35:48 (1975).

An experimental paper reporting discovery of a reentrant nematic phase in which a higher symmetry phase occurs at a lower temperature than one of lower symmetry. Later work gave a microscopic interpretation of the reentrant nematic phenomena. See: Reentrant Transitions in Liquid Crystals, Physical Properties of Liquid Crystals, D. Demus et al. (eds), Wiley-VCH Publishers, Weinheim, Germany (1999) p. 289.

• "'Soliton switch' in chiral smectic liquid crystals." Phys. Rev. A28Rap.Comm.:512 (1983), with H.R. Brand and P.L. Finn.

First interpretation of switching phenomena in chiral smectic-C's as a non-linear phenomena without a threshold. This has important implications for the display industry.

• "Phase winding and flow alignment in freely suspended films of smectic-C liquid crystals," Phys. Rev. Lett. 55:2945 (1985), with P. Pieranski and R. Barbet-Massin.

First experimental study of shear-flow-induced behavior in a two-dimensional anisotropic fluid: circular, freely suspended films of smectic-C liquid crystals. This lead to subsequent work on freely suspended films in rotating electric fields and the discovery of dynamic objects, spiral-target bound pairs.

• "Dynamical test of phase transition order," Phys. Rev. Lett. 62:1764 (1989), with W. van Saarloos, D.A. Huse, J.S. Patel, J.W. Goodby and P.L. Finn.

The first test of the order of a thermodynamic liquid crystal phase transition by front propagation which turns out to be a least 100 times more sensitive than classical techniques. In collaboration with Russian colleagues, we later used this test to obtain an estimate of the magnitude of the gap in a certain fluctuation spectrum. See: Fluctuations and Liquid Crystal Phase Transitions, Physical Properties of Liquid Crystals, D. Demus et al. (eds), Wiley-VCH Publishers, Weinheim, Germany (1999) p. 277.

• "Symmetry and Defects in the CM Phase of Polymeric Liquid Crystals," Macromolecules 25:7223 (1992),with H. R. Brand and H. Pleiner.

Prediction that banana-shaped liquid crystal molecules without any asymmetric carbons can have a spontaneous polarization (now observed). Antiferroelectric liquid crystals (smectic-CA) are a phase distinguishable from smectic-C*.

Kreeger Wolf Distinguished Professor, Northwestern University 1975
Fellow, American Physical Society 1983
Guggenheim Fellowship 1993
Alexander von Humboldt-Foundation Research Prize 1996

1960-62 Meterologist, Department of Transport, Canada
1962-63 Programmer-Analyst, KCS Ltd., Toronto, Canada
1963-64 Assistant Professor of Physics, Western Connecticut State College
1964-68 Research Assistant, University of Rochester
1969-72 Chargée de Recherche, Université de Paris (Orsay)
1972-present Research Physicist, Bell Laboratories and Lucent Technologies
1986-93 Editorial Board, Liquid Crystals Between 1975-94, also held visiting appointments at Northwestern University, University of Paris (Orsay), Ecole Pratique des Hautes Etudes (Paris), Ecole Normal Supérieure (Paris), Weizmann Institute (Israel), University of Essen (FRG), and University of Bayreuth (FRG)

B.A. (Combined Honours Mathematics and Physics) University of British Columbia 1959
M.A. (physics) University of Toronto 1960
Ph.D. (physics-superconductivity) University of Rochester 1968

Sources and References consulted:

Patricia E. Cladis and [4B AMWS]

Born in Shanghai, China in 1937.

Married George Cladis in 1962; two children Harrison M. and Franklyn P.  .

Physics is a way of thinking. It is not one thought. It's a powerful way of thinking because it leads to new knowledge. Like art and love, it's a universal language. -- Patricia Cladis

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