Brown University

About: Brown University is a education organization based out in Providence, Rhode Island, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 35778 authors who have published 90896 publications receiving 4471489 citations. The organization is also known as: brown.edu & Brown.

Fields of Experts: a framework for learning image priors

Abstract: We develop a framework for learning generic, expressive image priors that capture the statistics of natural scenes and can be used for a variety of machine vision tasks. The approach extends traditional Markov random field (MRF) models by learning potential functions over extended pixel neighborhoods. Field potentials are modeled using a Products-of-Experts framework that exploits nonlinear functions of many linear filter responses. In contrast to previous MRF approaches all parameters, including the linear filters themselves, are learned from training data. We demonstrate the capabilities of this Field of Experts model with two example applications, image denoising and image inpainting, which are implemented using a simple, approximate inference scheme. While the model is trained on a generic image database and is not tuned toward a specific application, we obtain results that compete with and even outperform specialized techniques.

Plasticity and primary motor cortex.

Abstract: One fundamental function of primary motor cortex (MI) is to control voluntary movements. Recent evidence suggests that this role emerges from distributed networks rather than discrete representations and that in adult mammals these networks are capable of modification. Neuronal recordings and activation patterns revealed with neuroimaging methods have shown considerable plasticity of MI representations and cell properties following pathological or traumatic changes and in relation to everyday experience, including motor-skill learning and cognitive motor actions. The intrinsic horizontal neuronal connections in MI are a strong candidate substrate for map reorganization: They interconnect large regions of MI, they show activity-dependent plasticity, and they modify in association with skill learning. These findings suggest that MI cortex is not simply a static motor control structure. It also contains a dynamic substrate that participates in motor learning and possibly in cognitive events as well.

Weak Absorption Tails in Amorphous Semiconductors

Abstract: Optical absorption measurements near the absorption edge are presented for three bulk semiconductor glasses: ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, ${\mathrm{Ge}}_{33}$${\mathrm{As}}_{12}$${\mathrm{Se}}_{55}$, and ${\mathrm{Ge}}_{28}$${\mathrm{Sb}}_{12}$${\mathrm{Se}}_{60}$. The weak absorption tails observed below the exponential part of the edge also follow an exponential law, and they are not due to a light-scattering artifact. We associate them with localized states in the band gap. The results are interpreted in terms of a model in which optical transitions occur between localized states below the mobility edge and extended states of the opposite band.

The oversocialized conception of man in modern sociology.

Abstract: Sociological theory originates in the asking of general questions about man and society. The answers lose their meaning if they are elaborated without reference to the questions, as has been the case in much contemporary theory. An example is the Hobbesian question of how men become tractable to social controls. The two-fold answer of contemporary theory is that man "internalizes" social norms and seeks a favorable self-image by conforming to the "expectations" of others. Such a model of man denies the very possibility of his being anything but a thoroughly socialized being and thus denies the reality of the Hobbesian question. The Freudian view of man, on the other hand, which sociologists have misrepresented, sees man as a social though never a fully socialized creature. Sociologists need to develop a more complex, dialectical conception of human nature instead of relying on an implicit conception that is tailor-made for special sociological problems.