Topics in equilibrium and nonequilibrium thermodynamics: computing crystalline free energies and engineering Maxwell’s demon.

This dissertation covers two separate topics in statistical physics. The first part of the dissertation focuses on computational methods of obtaining the free energies (or partition functions) of crystalline solids. We describe a method to compute the Helmholtz free energy of a crystalline solid by direct evaluation of the partition function. In the many-dimensional conformation space of all possible arrangements of N particles inside a periodic box, the energy landscape consists of localized islands corresponding to different solid phases. Calculating the partition function for a specific phase involves integrating over the corresponding island. Introducing a natural order parameter that quantifies the net displacement of particles from lattices sites, we write the partition function in terms of a one-dimensional integral along the order parameter, and evaluate this integral using umbrella sampling. We validate the method by computing free energies of both face-centered cubic (FCC) and hexagonal close-packed (HCP) hard sphere crystals with a precision of $10^{-5}k_BT$ per particle. In developing the numerical method, we find several scaling properties of crystalline solids in the thermodynamic limit. Using these scaling properties, we derive an explicit asymptotic formula for the free energy per particle in the thermodynamic limit. In addition, we describe several changes of coordinates that can be used to separate internal degrees of freedom from external, translational degrees of freedom. The second part of the dissertation focuses on engineering idealized physical devices that work as Maxwell's demon. We describe two autonomous mechanical devices that extract energy from a single heat bath and convert it into work, while writing information onto memory registers. Additionally, both devices can operate as Landauer's eraser, namely they can erase information from a memory register, while energy is dissipated into the heat bath. The phase diagrams and the efficiencies of the two models are solved and analyzed. These two models provide concrete physical illustrations of the thermodynamic consequences of information processing.

Sentimentos das crianças face aos professores

Este trabalho centra-se na análise dos sentimentos das crianças emergentes da relação aluno-professor. A investigação empírica enquadra-se na teoria das representações sociais, tendo como principal objectivo identificar os sentimentos mais comuns das crianças, em particular em relação aos seus professores, numa população de 120 sujeitos de ambos os sexos, com idades compreendidas entre os 8-11 anos de idade, alunos do 1.o e 2.o ciclos do Ensino Básico. Os dados foram recolhidos por associação livre de palavras e tratados através de AFC 1 Verificámos existir proximidade das representações das raparigas com as das crianças mais novas, salientando fortes sentimentos positivos, mostrando-se bastante motivadas e valorizando as relações interpessoais. Em comparação, as crianças de 10-11 anos e os rapazes, relevaram sobretudo dimensões tisicas, cognitivas e emocionais, associadas ao mal-estar e aborrecimento. Os resultados contribuem para compreender o universo cognitivo, emocional e relacional das crianças, na sua vivência quotidiana. ABSTRACT; This work is focused on the analysis of children's feelings emerging from the relation student-teacher. This empirical research lies within the scope of the theory of social representations, and its main objective is to identify the most common feelings in children, particularly towards their teachers, in a population of 120 subjects of both sexes, between the ages of 8 and 11, and attending the 1st and 2nd stages of Basic Education. The data was gathered using free word association, and examined through FAC2. We verified that the girls' representations were closer to the representations of younger children, and gave relevance to strong positive feelings, revealing a great motivation and validation of personal relations. By comparison, children aged 1O and 11, as well as boys, mainly gave relevance to physical, cognitive, and emotional dimensions, associated to uneasiness and boredom. The results contribute to the understanding of the cognitive, emotional, and relational universe of children in their daily lives.

From emotional suppression to regulated empathy : the changing face of control in the CES

Between the 1970s and the 1990s the level and type of emotionality in the Commonwealth Employment Service (the Australian national employment service) altered. Within a context of changing economic conditions and concomitant work intensification, it is argued that untenable working conditions resulted in new recruits adopting a coping strategy that led to the use rather than the suppression of emotions. The use of emotions provided workers with job satisfaction and greater control over service interactions. Management subsequently commandeered the use of emotions to complement the introduction of private sector management techniques and service delivery reforms, regaining control over worker-client interactions.