The electro-optical properties of polymer dispersed liquid crystal (PDLC) films are highly dependent on the features of the contained liquid crystal (LC) droplets. Cholesteric LC droplets with homeotropic boundaries can form several topologically different orientational structures, including ones with single and more point defects, layer-like, and axisymmetric twisted toroidal structures. These structures are very sensitive to an applied electric field. In this work, we have demonstrated experimentally and by computer simulations that twisted toroidal droplets reveal strong structural response to the electric field. In turn, this leads to vivid changes in the optical texture in crossed polarizers. The response of droplets of different sizes were found to be equivalent in terms of dimensionless parameters. In addition, the explanation of this phenomenon showed a comparison of theoretical and experimental structural response curves aids to determine the shape of the droplet. Finally, we demonstrated that the addition of a dichroic dye allows such films to be used as optical filters with adjustable color even without polarizers.
In this work, we investigated the behavior of cholesteric droplets with homeotropic boundary conditions experimentally and by computer simulations. Small droplets forming twisted radial structures were studied. We obtained two different paths of structural transformations under electric field in such droplets. The choice between these paths has probabilistic nature. The ratio between the two transition types was found to be sensitive to the elastic constants of LC forming the droplet. We suggest the principal approach for in situ estimation of ratios between elastic constants in cholesteric LCs deposited in polymer-dispersed LC material and discuss its strong and weak sides.
Background. Although planning disorders in schizophrenia are a fairly reliably established fact, the mechanisms of these disorders remain not fully clarified. Given the complex nature of planning, the presence of its disturbances can be influenced by disturbances of other mental processes. Objective. Comparison of the links between planning, short-term memory, attention and abstract thinking in patients with schizophrenia and in normal. Design. 50 patients with schizophrenia (14 females, age 34.92±8.54; illness duration 8.34±5.87) and 50 healthy volunteers (14 females, age 32.42±7.26) were examined. Assessment included: Tower of London-Test (TOL-DX) for planning assessment; Benton’s test (BVTR) for short-term memory assessment; sub-test Similarity (from WAIS) for abstract thinking assessment; Schulte Tables for assessment of attention; Wisconsin Card Sorting Test to assess cognitive flexibility. Results. Patients showed significantly worse results in all parameters, which indicates that patients have impairments in all assessed cognitive functions. The revealed relationships between planning and other cognitive processes in schizophrenic patients and healthy subjects were significantly different. In healthy subjects, the effectiveness of planning was found to be associated only with abstract thinking. At the same time, in patients with schizophrenia, associations were found between the effectiveness of planning and all the other cognitive processes (short-term memory, attention, set-shifting). Conclusion. The preservation of planning in schizophrenia is associated with the preservation of other mental processes. Short-term memory and attention are necessary, but not sufficient conditions for the realization of the planning process.
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