From Laser Induced Line Narrowing To Electromagnetically Induced Transparency: Closed System Analysis

Laser induced line narrowing effect, discovered more than thirty years ago, can also be applied to recent studies in high resolution spectroscopy based on electromagnetically induced transparency. In this paper we first present a general form of the transmission width of electromagnetically induced transparency in a homogeneously broadened medium. We then analyze a Doppler broadened medium by using a Lorentzian function as the atomic velocity distribution. The dependence of the transmission linewidth on the driving field intensity is discussed and compared to the laser induced line narrowing effect. This dependence can be characterized by a parameter which can be regarded as ``the degree of optical pumping''.Comment: 8 pages, 5 figure

A Computational Model of the Development of Separate Representations of Facial Identity and Expression in the Primate Visual System

Experimental studies have provided evidence that the visual processing areas of the primate brain represent facial identity and facial expression within different subpopulations of neurons. For example, in non-human primates there is evidence that cells within the inferior temporal gyrus (TE) respond primarily to facial identity, while cells within the superior temporal sulcus (STS) respond to facial expression. More recently, it has been found that the orbitofrontal cortex (OFC) of non-human primates contains some cells that respond exclusively to changes in facial identity, while other cells respond exclusively to facial expression. How might the primate visual system develop physically separate representations of facial identity and expression given that the visual system is always exposed to simultaneous combinations of facial identity and expression during learning? In this paper, a biologically plausible neural network model, VisNet, of the ventral visual pathway is trained on a set of carefully-designed cartoon faces with different identities and expressions. The VisNet model architecture is composed of a hierarchical series of four Self-Organising Maps (SOMs), with associative learning in the feedforward synaptic connections between successive layers. During learning, the network develops separate clusters of cells that respond exclusively to either facial identity or facial expression. We interpret the performance of the network in terms of the learning properties of SOMs, which are able to exploit the statistical indendependence between facial identity and expression

Reinventando governos locais durante a democratização: dinâmicas políticas e a criação de novos municípios no Brasil e na África do Sul

Este artigo estabelece uma ligação entre as mudanças institucionais dos governos locais e a autonomia local sob dinâmicas políticas federativas. Para tal efeito, o artigo examina como os governos locais no Brasil e na África do Sul ganharam autonomia administrativa e fiscal através da criação de novos municípios. Enfocando nos incentivos institucionais por trás dessas transformações, o artigo identifica e analisa como o aumento de municípios no Brasil e a redução de municípios Sul-Africanos afetaram o poder de seus respectivos governos locais. Os resultados da análise sugerem que, usando distintos processos de reinvenção de novos governos locais e a criação de instituições intergovernamentais de cooperação, os atores políticos locais em ambos os países aumentaram o seu poder vis-à-vis outras esferas de governo