32 research outputs found
Variational theory of confinement effects on cholesteric liquid crystals
Get PDFThis thesis is devoted to a theoretical description of the effects of confinement in cholesteric liquid crystals. The project is inspired by recent experimental works on cholesteric droplets based on amyloid fibrils. Particularly, four phase transitions were observed in droplets surrounded by isotropic fluid, at growing volumes.
The complete phenomenology has to date not yet been described or predicted from a theoretical perspective. Simple scaling arguments based on bulk terms of the Frank-Oseen (FO) energy-density functional have been found only for the first three phases, so that a more thorough analysis is needed. In this thesis, we will address the issue by means of a variational approach, with particular focus on understanding how confinement affects the various terms of the FO functional, for both bulk and surface terms. This will serve to rationalize the experimental findings observed on amyloid-based systems, as well as provide a basis for more refined theoretical approaches. In this thesis we propose two models to explain the whole phenomenology presented by the system, and introduce scaling laws for the three phase transitions
Homoclinic chaos and the Poincaré-Melnikov method
Get PDFIn this thesis is to describe the use of the Poincaré-Melnikov method in the detection of homoclinic phenomena, and hence chaotic dynamics.
After a short review of the theory of dynamical system, it is introduced the Poincaré-Melnikov method and its extension to the case of heteroclinic orbits.
An application of this method is given in the last chapter, where it is shown a case of success and a case of failure in the detection of chaos.
Results are confirmed through numerical evidence.ope
Variational theory of confinement effects on cholesteric liquid crystals
Get PDFThis thesis is devoted to a theoretical description of the effects of confinement in cholesteric liquid crystals. The project is inspired by recent experimental works on cholesteric droplets based on amyloid fibrils. Particularly, four phase transitions were observed in droplets surrounded by isotropic fluid, at growing volumes.
The complete phenomenology has to date not yet been described or predicted from a theoretical perspective. Simple scaling arguments based on bulk terms of the Frank-Oseen (FO) energy-density functional have been found only for the first three phases, so that a more thorough analysis is needed. In this thesis, we will address the issue by means of a variational approach, with particular focus on understanding how confinement affects the various terms of the FO functional, for both bulk and surface terms. This will serve to rationalize the experimental findings observed on amyloid-based systems, as well as provide a basis for more refined theoretical approaches. In this thesis we propose two models to explain the whole phenomenology presented by the system, and introduce scaling laws for the three phase transitions.ope
Homoclinic chaos and the Poincaré-Melnikov method
Get PDFIn this thesis is to describe the use of the Poincaré-Melnikov method in the detection of homoclinic phenomena, and hence chaotic dynamics.
After a short review of the theory of dynamical system, it is introduced the Poincaré-Melnikov method and its extension to the case of heteroclinic orbits.
An application of this method is given in the last chapter, where it is shown a case of success and a case of failure in the detection of chaos.
Results are confirmed through numerical evidence
Epitomare nella scuola di retorica: Giulio Paride e Ianuario Nepoziano
Get PDFIl contributo si concentra sulle epitomi ai Facta et dicta memorabilia di Valerio Massimo, un autore di età tiberiana che fu lui stesso un selezionatore ed epitomatore di opere precedenti. Le due epitomi conservate risalgono all’età tardoantica: quella di Giulio Paride è giunta a noi completa, mentre quella di Ianuario Nepoziano arriva fino all’inizio del terzo libro di Valerio Massimo (3, 2, 7). In questo studio analizzo i proemi delle due epitomi per far emergere i principi metodologici che guidarono gli autori. Successivamente presento un caso di studio con l’analisi delle strategie testuali che portarono dal testo di partenza (un passo di Tito Livio) alle riscritture, prima di Valerio Massimo, poi di Giulio Paride e Nepoziano. Infine, per entrare ancora meglio nel laboratorio dell’epitomatore, propongo alcune osservazioni sugli aneddoti aggiunti da Nepoziano alla raccolta di Valerio Massimo.The contribution focuses on the epitomes to the Facta et dicta memorabilia of Valerius Maximus, an author of Tiberian age who was himself a selector and epitomator of previous literary works. The two epitomes date back to the Late Antiquity: the epitome of Iulius Paris is complete, whereas the epitome of Ianuarius Nepotianus is interrupted at the beginning of Valerius Maximus’ third book (3, 2, 7). The paper analyses the dedicatory letters of the two epitomes to bring out the methodological principles that guided the authors. Then, a case study is presented to explain the textual strategies that led from the source text (a passage by Livy) to its rewrites, first in Valerius Maximus, then in Iulius Paris and Nepotianus. Finally, to get even better into the epitomator’s workshop, some observations are made on the anecdotes that Nepotianus added to the works of Valerius Maximus
Liquid-liquid crystalline phase separation in biological filamentous colloids: nucleation, growth and order-order transitions of cholesteric tactoids
No full textISSN:1744-683XISSN:1744-6848ISSN:1744-684
