1,721,046 research outputs found
The liquid crystal phases: physics and technology
No full textLiquid crystals are interesting both for fundamental reasons and because of their application in display device technology. I give an overview of the liquid crystal phases. I then describe in more detail some of the basic physics of nematic liquid crystals, concentrating on those pieces of physics which underly display device technology. Finally I give a brief description of some of the most important liquid crystal applications
Vito Volterra at 150
No full textThe year 2010 marked the one hundred and fiftieth anniversary of the birth of the great Italian mathematician Vito Volterra (1860–1940), who can justly be regarded as the most important Italian mathematician of the modern era. His mathematical work stretches over a 59-year period, from his first paper in 1881, to his last, shortly before his death
Fluidos fora da lei
No full textA popular history of liquid crystals from the early days in the late 19th century to the present day, when liquid crystals displays are ubiquitous
Some reflections on defects in liquid crystals: From Amerio to Zannoni and beyond
No full textDedicated to Claudio Zannoni on the occasion of his 70th birthday. I discuss some aspects of the history of dislocations, disclinations, and defects in liquid crystals, virtual and otherwise, placing Claudio Zannoni in the grand tradition of Italian science
Ueber die natur der kristallinischen Flussigkeiten und flüssigen Kristalle (The early history of liquid crystals)
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The writhing on the wall: first comprehensive steps toward a comprehensive theory of liquid crystal surfaces
No full textA commentary on the paper "Theory of the isotropic-nematic transition in a restricted geometry", first published in "Liquid Crystals" vol 2, pp281-311 (1987)
Zigzagging: theoretical insights on climbing strategies
No full textHuman and animal trails on steep hillsides often exhibit dramatic switchbacks and shortcuts. Helbing et al. have recently examined the emergence of human trail systems on flat terrains while Minetti and Margaria established the effect of gradients on human metabolic efficiency. In this paper we use these ideas to develop a semi-quantitative theoretical model of the behaviour of humans moving on a terrain with relief. The model determines the direction of movement by minimising metabolic cost per unit of distance in a desired direction. The structure of the theory resembles the Landau Theory of Phase Transitions, much used in theoretical physics. We find that both hairpin bends (switchbacks) and shortcuts appear as efficient strategies for downhill walkers, while uphill walkers retain switchbacks. For weakly inclined slopes, the best strategy involves walking directly uphill or downhill. For sufficiently steep slopes, however, we find that the best strategy should undergo a transition to a broken symmetry solution corresponding to the switchback trail patterns typical of rugged environments. The critical slope at which this transition takes place should be less steep for uphill and downhill walkers. The theory should be amenable to empirical investigation. Amongst other applications, this model will enable us to generalize the work of previous authors to real landscapes, eventually permitting the reconstruction of ancient patterns of movement in archaeological landscapes
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