169 research outputs found
Axion Isocurvature and Magnetic Monopoles
We propose a simple mechanism to suppress axion isocurvature fluctuations
using hidden sector magnetic monopoles. This allows for the Peccei-Quinn scale
to be of order the unification scale consistently with high scale inflation.Comment: 13 page
Flat-space Quantum Gravity in AdS/CFT
Motivated by the task of understanding microscopic dynamics of an evolving
black hole, we present a scheme describing gauge-fixed continuous time
evolution of quantum gravitational processes in asymptotically flat spacetime
using the algebra of CFT operators. This allows us to study the microscopic
dynamics of the Hawking emission process, although obtaining a full S-matrix
may require a modification of the minimal scheme. The role of the operator
product expansion is to physically interpret the resulting time evolution by
decomposing the Hilbert space of the states for the entire system into those
for smaller subsystems. We translate the picture of an evaporating black hole
previously proposed by the authors into predictions for nonperturbative
properties of the CFTs that have weakly coupled dual gravitational
descriptions. We also discuss a possible relationship between the present
scheme and a reference frame change in the bulk.Comment: 31 pages, 2 figures; clarifications adde
Relativeness in Quantum Gravity: Limitations and Frame Dependence of Semiclassical Descriptions
Consistency between quantum mechanical and general relativistic views of the
world is a longstanding problem, which becomes particularly prominent in black
hole physics. We develop a coherent picture addressing this issue by studying
the quantum mechanics of an evolving black hole. After interpreting the
Bekenstein-Hawking entropy as the entropy representing the degrees of freedom
that are coarse-grained to obtain a semiclassical description from the
microscopic theory of quantum gravity, we discuss the properties these degrees
of freedom exhibit when viewed from the semiclassical standpoint. We are led to
the conclusion that they show features which we call extreme relativeness and
spacetime-matter duality---a nontrivial reference frame dependence of their
spacetime distribution and the dual roles they play as the "constituents" of
spacetime and as thermal radiation. We describe black hole formation and
evaporation processes in distant and infalling reference frames, showing that
these two properties allow us to avoid the arguments for firewalls and to make
the existence of the black hole interior consistent with unitary evolution in
the sense of complementarity. Our analysis provides a concrete answer to how
information can be preserved at the quantum level throughout the evolution of a
black hole, and gives a basic picture of how general coordinate transformations
may work at the level of full quantum gravity beyond the approximation of
semiclassical theory.Comment: 44 pages, 4 figures; typos correcte
Essays on estimation of dynamic games
This thesis considers estimation of discrete choice stationary dynamic games. Chapter 1 shows that when payoffs are linear in the parameters value functions are linear in the parameters and the equation system characterizing the Markovian equilibrium is linear in the parameters. This formulation allows us to estimate the model using Least Squares. We derive an optimal weight matrix for the Least Squares estimator and show that the efficient estimator is a Generalized Least Squares estimator. Chapter 2 shows that when time invariant unobservables are present the efficient estimator is a Generalized Fixed Effects estimator. Time invariant unobservables can be correlated with observed states. We do not need to impose any distributional assumption on time invariant unobservables. Our estimators have a closed form solution. In Chapter 3 we apply the framework developed in Chapters 1 and 2 to analyze the effects of the privatization of public banks on financial development. We build a dynamic entry game to analyze the Brazilian banking market. We show that profits of private banks are positively affected by the number of public branches operating in Brazilian isolated markets. The spill-over generated by public banks is quantified based on a dynamic oligopoly model. A counterfactual in which public banks are privatized is examined. It shows that the number of active branches operating in the long-run in a small market drops significantly
Spacetime Equals Entanglement
We study the Hilbert space structure of classical spacetimes under the
assumption that entanglement in holographic theories determines semiclassical
geometry. We show that this simple assumption has profound implications; for
example, a superposition of classical spacetimes may lead to another classical
spacetime. Despite its unconventional nature, this picture admits the standard
interpretation of superpositions of well-defined semiclassical spacetimes in
the limit that the number of holographic degrees of freedom becomes large. We
illustrate these ideas using a model for the holographic theory of cosmological
spacetimes.Comment: 6 pages, 2 figures; v2: remarks on time evolution revised, v3:
matches published versio
GRUPO OPERATIVO COM ESTUDANTES DE ENFERMAGEM: VIVÊNCIA EM UMA LIGA ACADÊMICA DE ONCOLOGIA
Objetivo: descrever uma atividade grupal desenvolvida em uma Liga Acadêmica de Prevenção ao Câncer. Método: relato de experiência em um grupo operativo realizado no primeiro semestre de 2019, em uma universidade pública do interior de São Paulo, com 27 graduandos do curso de Enfermagem com idades entre 17 e 25 anos, cursando entre o primeiro e o sétimo períodos letivos. Resultados: nas discussões grupais emergiram quatro temas, evidenciando aspectos do contexto de adoecimento por câncer, como estigmas, medos, anseios, fantasias, vivências do câncer como uma doença agressiva e limitante para o acometido e sua família, além de recursos de enfrentamento, como a religiosidade/espiritualidade. Conclusão: a atividade grupal desenvolvida em uma Liga Acadêmica de Prevenção ao Câncer evidenciou a importância de a oncologia ser trabalhada na formação de Enfermagem, capacitando os estudantes para lidarem com situações de intervenção e prepararem-se emocionalmente para os desafios que podem emergir nesse campo de atuação futura.Descritores: Educação em Enfermagem. Educação em Saúde. Grupos Focais. Oncologia. Psico-Oncologia
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