Neutron Star Vortex Dynamics and Magnetic Field Decay: Implications for High Density Nuclear Matter

We investigate the effect of the density-dependent proton and neutron gaps on vortex dynamics in neutron stars. We argue that the persistence of neutron star magnetic fields on timescales of $10^9$ y suggests a superconducting gap curve with local maximum at intermediate density. We discuss the implications for exotic core phenomena such as pion/kaon condensation or a transition to quark matter.Comment: 7 pages, 2 figures, uses LaTe

Some hidden benefits of the urban forest

https://deepblue.lib.umich.edu/bitstream/2027.42/150714/1/2004_Kaplan_Some_hidden_benefits.pd

Texture-Based Processing in Early Vision and a Proposed Role for Coarse-Scale Segmentation

Humans and other natural systems are remarkably adept at extracting spatial information from vision. To better understand this process, it would be useful to know how the visual system can make an initial estimate of where things are in a scene and how they are oriented. Texture is one source of information that the visual system can use for this purpose. It can be used both for segmenting the visual input and for estimating spatial orientations within segmented regions; moreover, each of these two processes can be performed starting with the same mechanisms, namely spatiotemporally-tuned cells in the visual cortex. But little attention has been given to the problem of integrating the two processes into a single system. In this paper, we discuss texture-based visual processing and review recent work in computer vision that offers insights into how a visual system could solve this problem. We then argue that a beneficial extension to these approaches would be to incorporate an initial coarse-scale segmentation step. We offer supporting evidence from psychophysics that the human visual system does in fact perform such a rough segmentation early in vision

Approximate Spatial Layout Processing in Early Vision

Imagine yourself running through rough terrain, perhaps fleeing a predator, or perhaps chasing after prey. Your visual system does not have time to scrutinize the countless trees, rocks, and other objects you pass by. What you need most is enough spatial information to avoid obstacles, to orient yourself, to pick a path. In this situation, even a rough sketch of the spatial layout of the environment can provide crucial information

Wavefunction Statistics using Scar States

We describe the statistics of chaotic wavefunctions near periodic orbits using a basis of states which optimise the effect of scarring. These states reflect the underlying structure of stable and unstable manifolds in phase space and provide a natural means of characterising scarring effects in individual wavefunctions as well as their collective statistical properties. In particular, these states may be used to find scarring in regions of the spectrum normally associated with antiscarring and suggest a characterisation of templates for scarred wavefunctions which vary over the spectrum. The results are applied to quantum maps and billiard systems.Comment: 31 pages, 11 figures, to appear in Annals of Physic

A MODIFIED DESIGN FOR THE LYKKEN ZINC ELECTRODES

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75070/1/j.1469-8986.1964.tb02625.x.pd

Hebb's Accomplishments Misunderstood

Amit's efforts to provide stronger theoretical and empirical support for Hebb's cell-assembly concept is admirable, but we have serious reservations about the perspective presented in the target article. For Hebb, the cell assembly was a building block; by contrast, the framework proposed here eschews the need to fit the assembly into a broader picture of its function

Prototypes, Location, and Associative Networks (PLAN): Towards a Unified Theory of Cognitive Mapping

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98111/1/s15516709cog1901_1.pd

Scarring and the statistics of tunnelling

We show that the statistics of tunnelling can be dramatically affected by scarring and derive distributions quantifying this effect. Strong deviations from the prediction of random matrix theory can be explained quantitatively by modifying the Gaussian distribution which describes wavefunction statistics. The modified distribution depends on classical parameters which are determined completely by linearised dynamics around a periodic orbit. This distribution generalises the scarring theory of Kaplan [Phys. Rev. Lett. {\bf 80}, 2582 (1998)] to describe the statistics of the components of the wavefunction in a complete basis, rather than overlaps with single Gaussian wavepackets. In particular it is shown that correlations in the components of the wavefunction are present, which can strongly influence tunnelling-rate statistics. The resulting distribution for tunnelling rates is tested successfully on a two-dimensional double-well potential.Comment: 20 pages, 4 figures, submitted to Ann. Phy