Forces due to structure in a thin liquid crystal film

Measurements of the force as a function of distance between two solids separated by a liquid crystal film give information on the structure of the film. We report such measurements for two molecularly smooth surfaces of mica separated by the nematic liquid crystal 4'-n-pentyl 4-cyanobiphenyl (5CB) in both the planar and homeotropic orientations at room temperature. The force is determined by measuring the deflection of a spring supporting one of the mica pieces, while an optical technique is used to measure the film thickness to an accuracy of ± (0.1-0.2) nm. The technique also allows the refractive indices of the nematic to be measured, and hence a determination of the average density and order parameter of the liquid crystal film as a function of its thickness. Three distinct forces were measured, each reflecting a type of ordering of the liquid crystal near the mica surfaces. The first one results from elastic déformation in the liquid crystal ; it was only observed in a twisted planar sample where the 5CB molecules are oriented in different directions at the two mica surfaces. The second, measured in both the planar and homeotropic orientations, is attributed to an enhanced order parameter near the surfaces. Both of these are monotonic repulsive forces measurable below 80 nm. Finally, there is a short-range force which oscillates as a function of thickness, up to about six molecular layers, between attraction and repulsion. This results from ordering of the molecules in layers adjacent to the smooth solid surface. It is observed in both the planar and homeotropic orientations, and also in isotropic liquids.

Ambient CINEMATIC SHORT

A creaking door, an ambient ethno underscore, a couple of synths and you may just have your moody composition.

Screening Sarah Bernhardt: reinterpreting acting in silent film

Sarah Bernhardt, the great nineteenth-century theatrical actress, was also the first major international film star. Appearing cross-dressed in a short Hamlet film before international audiences at the Paris Exposition of 1900, this 56-year-old French actress most famously went on to make Camille (La Dame aux Camélias, 1911) and Queen Elizabeth (Les Amours de la Reine Elisabeth, 1912). Later appearing in one of the first celebrity home movies (Sarah Bernhardt at Home, 1915), she also made a WWI propaganda film, Mothers of France (Mères Françaises, 1917). This presentation explores these films as evidence of a productive exchange between the stage and the nascent film industry. Rather than see Bernhardt’s acting as evidence of the theatre’s incommensurability with film, it will demonstrate the legacy of her stage acting as she adapted it to early film. The talk will include screenings of the films accompanied by live music.

Material damage: 4 projector film performance

Dirk de Bruyn’s expanded cinema performances engage the æsthetics of process at a number of levels. At the core of these performances are several of three- or four-screen, essentially abstract films of the same duration which comment upon and echo each other in a constant interplay of flicker-like positive and negative imagery. The soundtrack of the films works in a related way: the same or similar words and sound fragments are overlayed, or are repeated in an absurd call-and-answer pattern running from one speaker to another. This overall design or formal system is then set into play and relativised in the live event through a number of treatment-techniques. Reels are placed out of order or interspliced with other short films or fragments of found footage or tests, the bulb of one or more projectors can be occasionally turned off while the soundtrack continues, or the projector can be stopped altogether, extending, stretching out or disrupting completely the apparent synchrony between each screen and soundtrack. The light beam of each projector is filtered, distorted, split and multiplied using hand-held colour gels, plastic bottles, prisms and mirrors, or else silhouetted or blocked completely with the artist’s own hands and body. The projectors themselves can be inverted, turned around or physically transported across the space, mixing and overlaying the imagery, animating different areas of the performance environment and transforming the body of the audience itself into a screen medium.