Absorption spectrum of iron in the vacuum ultraviolet 2950 - 1588 angstrom

Absorption spectrum of iron in vacuum ultraviole

Environmental legislation as a driver of design

and other research output

Two-Particle Microrheology of quasi-2D Viscous Systems

We study the correlated motions of colloidal particles in a quasi-2D system (Human Serum Albumin (HSA) protein molecules at an air-water interface) for different surface viscosities $\eta_{s}$. We observe a transition in the behavior of the correlated motion, from 2-D interface dominated at high $\eta_{s}$ to bulk fluid-dependent at low $\eta_{s}$. The correlated motions can be scaled onto a master curve which captures the features of this transition. This master curve also characterizes the spatial dependence of the flow field of a viscous interface in response to a force. From the flow field and the correlated particle motions, we calculate a two-particle MSD (mean square displacement) for direct comparison with rheological measurements.Comment: 4 pages, 4 figures, submitted to PR

Properties of cage rearrangements observed near the colloidal glass transition

We use confocal microscopy to study the motions of particles in concentrated colloidal systems. Near the glass transition, diffusive motion is inhibited, as particles spend time trapped in transient ``cages'' formed by neighboring particles. We measure the cage sizes and lifetimes, which respectively shrink and grow as the glass transition approaches. Cage rearrangements are more prevalent in regions with lower local concentrations and higher disorder. Neighboring rearranging particles typically move in parallel directions, although a nontrivial fraction move in anti-parallel directions, usually from pairs of particles with initial separations corresponding to the local maxima and minima of the pair correlation function $g(r)$, respectively.Comment: 5 pages, 4 figures; text & figures revised in v

Hicks v. Dowd, Conservation Easements, and the Charitable Trust Doctrine: Setting the Record Straight

This is the fourth in an exchange of articles published by the Wyoming Law Review discussing the application of charitable trust principles to conservation easements conveyed as charitable gifts. In 2002, Johnson County, Wyoming, attempted to terminate a conservation easement that had been conveyed to the County as a tax-deductible charitable gift. The County\u27s actions were challenged, first in a suit brought by a resident of the County, Hicks v. Dowd, and then in a suit brought by the Wyoming Attorney General, Salzburg v. Dowd. The over six years of litigation associated with the easement\u27s attempted termination has been the catalyst and background for the exchange of articles

Hicks v. Dowd, Conservation Easements, and the Charitable Trust Doctrine: Setting the Record Straight

This is the fourth in an exchange of articles published by the Wyoming Law Review discussing the application of charitable trust principles to conservation easements conveyed as charitable gifts. In 2002, Johnson County, Wyoming, attempted to terminate a conservation easement that had been conveyed to the County as a tax-deductible charitable gift. The County\u27s actions were challenged, first in a suit brought by a resident of the County, Hicks v. Dowd, and then in a suit brought by the Wyoming Attorney General, Salzburg v. Dowd. The over six years of litigation associated with the easement\u27s attempted termination has been the catalyst and background for the exchange of articles

Circles in the Sky: Finding Topology with the Microwave Background Radiation

If the universe is finite and smaller than the distance to the surface of last scatter, then the signature of the topology of the universe is writ large on the microwave background sky. We show that the microwave background will be identified at the intersections of the surface of last scattering as seen by different ``copies'' of the observer. Since the surface of last scattering is a two-sphere, these intersections will be circles, regardless of the background geometry or topology. We therefore propose a statistic that is sensitive to all small, locally homogeneous topologies. Here, small means that the distance to the surface of last scatter is smaller than the ``topology scale'' of the universe.Comment: 14 pages, 10 figures, IOP format. This paper is a direct descendant of gr-qc/9602039. To appear in a special proceedings issue of Class. Quant. Grav. covering the Cleveland Topology & Cosmology Worksho

Attraction Between Like-Charged Walls: Short-Ranged Simulations Using Local Molecular Field Theory

Effective attraction between like-charged walls mediated by counterions is studied using local molecular field (LMF) theory. Monte Carlo simulations of the "mimic system'' given by LMF theory, with short-ranged "Coulomb core" interactions in an effective single particle potential incorporating a mean-field average of the long-ranged Coulomb interactions, provide a direct test of the theory, and are in excellent agreement with more complex simulations of the full Coulomb system by Moreira and Netz [Eur. Phys. J. E 8, 33 (2002)]. A simple, generally-applicable criterion to determine the consistency parameter sigma_{min} needed for accurate use of the LMF theory is presented

Direct visualization of aging in colloidal glasses

We use confocal microscopy to directly visualize the dynamics of aging colloidal glasses. We prepare a colloidal suspension at high density, a simple model system which shares many properties with other glasses, and initiate experiments by stirring the sample. We follow the motion of several thousand colloidal particles after the stirring and observe that their motion significantly slows as the sample ages. The aging is both spatially and temporally heterogeneous. Furthermore, while the characteristic relaxation time scale grows with the age of the sample, nontrivial particle motions continue to occur on all time scales.Comment: submitted to proceedings for Liquid Matter Conference 200