Unraveling the Dynamics and Equilibrium Behavior of Pure and Mixed Micelles: Insights from Microscopic coarse-grain modeling

Aquesta tesi es centra en explorar i controlar els mecanismes darrere de la formació i el comportament dinàmic de micel?les pures i mixtes, les quals són àmpliament utilitzades en moltes indústries. Es proposen simulacions de camp mitjà d'una cadena única de models \textit{coarse-grain} com una forma ràpida i eficient d'explorar aquests sistemes moleculars complexos. La tesi es divideix en dues parts, la primera de les quals explora el comportament dinàmic de les micel?les utilitzant funcions de correlació temporal i simulacions de la teoria dinàmica de camp mitjà d'una sola cadena. Els resultats mostren que la sortida de copolímers poloxàmer de les micel?les exhibeix quatre règims distintius: una ràpida reorganització, un règim intermedi logarítmic, un règim intermedi exponencial i una decadència exponencial final. Es va observar que la resposta logarítmica prèviament creguda degut a la polidispersitat també pot sorgir de la degeneració d'estats d'energia del bloc hidrofòbic en el nucli de la micel?la. Aquesta troballa suggereix que la resposta dinàmica a curt termini d'aquests sistemes té un origen entròpic en lloc de ser influïda per la polidispersitat, com es pensava anteriorment. Es va proposar una equació d'Eyring modificada per reproduir el comportament dinàmic observat.Esta tesis se centra en explorar y controlar los mecanismos detrás de la formación y el comportamiento dinámico de micelas puras y mixtas, las cuales son ampliamente utilizadas en muchas industrias. Se proponen simulaciones de campo medio de una cadena única de modelos \textit{ coarse-grain} como una forma rápida y eficiente de explorar estos sistemas moleculares complejos. La tesis se divide en dos partes, la primera de las cuales explora el comportamiento dinámico de las micelas utilizando funciones de correlación temporal y simulaciones de la teoría dinámica de campo medio de una sola cadena. Los resultados muestran que la salida de copolímeros poloxámero de las micelas exhibe cuatro regímenes distintos: una rápida reorganización, un régimen intermedio logarítmico, un régimen intermedio exponencial, y una decadencia exponencial final. Se observó que la respuesta logarítmica previamente creída debido a la polidispersidad también puede surgir de la degeneración de estados de energía del bloque hidrofóbico en el núcleo de la micela. Este hallazgo sugiere que la respuesta dinámica a corto plazo de estos sistemas tiene un origen entrópico en lugar de ser influenciada por la polidispersidad, como se pensaba anteriormenteThis thesis focuses on exploring and controlling the mechanisms behind the formation and dynamic behavior of pure and mixed micelles, which are widely used across many industries. Single-Chain Mean-Field simulations of coarse-grain models are proposed as a quick and efficient way to explore these complex molecular systems. The thesis is divided into two parts, the first of which explores the dynamic behavior of micelles using time correlation functions and dynamic Single-Chain Mean-Field theory simulations. The results show that the exit of poloxamer copolymers from micelles exhibits four distinct regimes: a fast reorganization, a logarithmic intermediate regime, an exponential intermediate regime, and a final exponential decay. It was observed that the logarithmic response previously believed to be due to polydispersity can also arise from the degeneracy of energy states of the hydrophobic block in the micelle core. This finding suggests that the short-time dynamic response of these systems has an entropic origin rather than being influenced by polydispersity as previously thought. A modified Eyring equation was proposed to reproduce the observed dynamic behavior. The second section of the thesis delves into the examination of the equilibrium behavior of mixed micelles utilizing the Single-Chain Mean-Field method for binary system

Higgs/amplitude mode dynamics from holography

Second order phase transitions are universally driven by an order parameter which becomes trivial at the critical point. At the same time, collective excitations which involve the amplitude of the order parameter develop a gap which smoothly closes to zero at criticality. We develop analytical techniques to study this “Higgs” mode in holographic systems which undergo a continuous phase transition at finite temperature and chemical potential. This allows us to study the linear response of the system at energy scales of the order of the gap. We express the Green’s functions of scalar operators in terms of thermodynamic quantities and a single transport coefficient which we fix in terms of black hole horizon data

Thermal three-point functions from holographic Schwinger-Keldysh contours

We compute fully retarded scalar three-point functions of holographic CFTs at finite temperature using real-time holography. They describe the nonlinear response of a holographic medium under scalar forcing, and display single and higher-order poles associated to resonant QNM excitations. This involves computing the bulk-to-bulk propagator on a piecewise mixed-signature spacetime, the dual of the Schwinger-Keldysh contour. We show this construction is equivalent to imposing ingoing boundary conditions on a single copy of a black hole spacetime, similar to the case of the two-point function. We also compute retarded scalar correlators with stress-tensor insertions in general CFTs by solving Ward identities on the Schwinger-Keldysh contour.Comment: 21 pages, 4 figures. Typo fixed and discussed FDT with bulk-bulk propagator

Black hole excited states from broken translations in Euclidean time

We prepare an excited finite temperature state in ${\cal N}=4$ SYM by means of a Euclidean path integral with a relevant deformation. The deformation explicitly breaks imaginary-time translations along the thermal circle whilst preserving its periodicity. We then study how the state relaxes to thermal equilibrium in real time. Computations are performed using real-time AdS/CFT, by constructing novel mixed-signature black holes in numerical relativity corresponding to Schwinger-Keldysh boundary conditions. These correspond to deformed cigar geometries in the Euclidean, glued to a pair of dynamical spacetimes in the Lorentzian. The maximal extension of the Lorentzian black hole exhibits a `causal shadow', a bulk region which is spacelike separated from both boundaries. We show that causal shadows are generic in path-integral prepared states where imaginary-time translations along the thermal circle are broken.Comment: 22 pages, 12 figures V2: references adde

Education Inequalities and Political Behaviour of the Young in Greece in the 2010s 1

In this paper we briefly address two issues related to the living conditions of youth in Greece and the way these conditions have changed during the 2010s. The first is about the educational trajectories of young Greeks which are leading to less promising prospects in the labour market and become increasingly unequal and socially selective during the crisis. The second issue is the political response of young Greeks to the crisis. There is evidence that they have been actively mobilized against austerity measures and, at the same time, they have increased their participation in the political system, both in confrontational and institutional politics. Inequalities are increasing and social mobility prospects for the young people are deteriorating. Their political response, however, is an outcome depending on many other factors with the politics of parties attractive to youngsters’ aspirations during the crisis being among the most important