MULTIPLE SPATIAL SCALE ANALYSIS OF WHOOPING CRANE HABITAT IN NEBRASKA

Geographic Information System (GIS) and remote sensing technologies were used to evaluate whooping crane stopover habitat in Nebraska. The goal of the research was to investigate habitat selection at multiple spatial scales. The GIS database consisted of all confirmed whooping crane sightings reported in Nebraska from 1975-1996 and land cover information delineated from color infrared aerial photographs and Landsat Thematic Mapper data. Results suggest that whooping cranes select roost habitat by recognizing site-level and landscape-scale land cover composition. Wetland is the most strongly selected habitat type at all spatial scales examined. This presentation emphasizes methods used to analyze habitat selection and how the information can be applied in conservation

Merging of the alpha and beta relaxations and aging via the Johari–Goldstein modes in rapidly quenched metallic glasses

This paper provides evidence that the physical aging of deeply and rapidly quenched metallic glasses is promoted by the Johari–Goldstein slow beta relaxation, resulting in a significant irreversible increase in the mechanical modulus on initial heating. Dynamic mechanical analysis has been used to characterize relaxation phenomena of a strong and a fragile metallic glass. In addition, we can extrapolate the temperature dependence of beta- and alpha-relaxation peaks to higher temperatures and calculate the merging temperature for both types of glasses

Dynamical and quasistatic structural relaxation paths in Pd_(40)Ni_(40)P_(20) glass

By sequential heat treatment of a Pd_(40)Ni_(40)P_(20) metallic glass at temperatures and durations for which α-relaxation is not possible, dynamic, and quasistatic relaxation paths below the glass transition are identified via ex situ ultrasonic measurements following each heat treatment. The dynamic relaxation paths are associated with hopping between nonequilibrium potential energy states of the glass, while the quasistatic relaxation path is associated with reversible β-relaxation events toward quasiequilibrium states. These quasiequilibrium states are identified with secondary potential energy minima that exist within the inherent energy minimum of the glass, thereby supporting the concept of the sub-basin/metabasin organization of the potential-energy landscape

Following microscopic motion in a two dimensional glass-forming binary fluid

The dynamics of a binary mixture of large and small discs are studied at temperatures approaching the glass transition using an analysis based on the topology of the Voronoi polygon surrounding each atom. At higher temperatures we find that dynamics is dominated by fluid-like motion that involves particles entering and exiting the nearest-neighbour shells of nearby particles. As the temperature is lowered, the rate of topological moves decreases and motion becomes localised to regions of mixed pentagons and heptagons. In addition we find that in the low temperature state particles may translate significant distances without undergoing changes in their nearest neig hbour shell. These results have implications for dynamical heterogeneities in glass forming liquids.Comment: 12 pages, 7 figure

Orono: Growing as a University Town, 1965-2015

By 1965, the Town of Orono’s long history as a lumber town had faded and it had grown into a small university town. Demographically and socially, Orono today demonstrates many of the markers of a university town—from its occupational profile and residency of university employees and students to its growing knowledge-based economy and its evolving downtown of “third places.” But there are differences, too, from a typical university town—for example, in the relative physical isolation of the University of Maine from the rest of the town, and in Orono’s small population compared with the university’s enrollment. Opinions on the quality of Orono as a university town vary, and the Town-Gown relationship cuts across several dimensions—economic, civic, public services and fiscal, social, and educational. These relationships are fluid, and both Town and University continue to work on balancing their respective interests and needs. For example, as of 2015 they continued to consider how best to accommodate student homes in neighborhoods; and how to expand the University of Maine’s role as the source of new industry for Orono and the state. Evan Richert, AICP, is the Town Planner for Orono and Sophia L. Wilson is the Town Manager of Orono

Localization Properties of Two Interacting Electrons in a Disordered Quasi One-Dimensional Potential

We study the transport properties of two electrons in a quasi one-dimensional disordered wire. The electrons are subject to both, a disorder potential and a short range two-body interaction. Using the approach developed by Iida et al. [ Ann. Phys. (N.Y.) 200 (1990) 219 ], the supersymmetry technique, and a suitable truncation of Hilbert space, we work out the two-point correlation function in the framework of a non-linear sigma model. We study the loop corrections to arbitrary order. We obtain a remarkably simple and physically transparent expression for the change of the localization length caused by the two-body interaction.Comment: 10 page

Mean-field glass transition in a model liquid

We investigate the liquid-glass phase transition in a system of point-like particles interacting via a finite-range attractive potential in D-dimensional space. The phase transition is driven by an `entropy crisis' where the available phase space volume collapses dramatically at the transition. We describe the general strategy underlying the first-principles replica calculation for this type of transition; its application to our model system then allows for an analytic description of the liquid-glass phase transition within a mean-field approximation, provided the parameters are chosen suitably. We find a transition exhibiting all the features associated with an `entropy crisis', including the characteristic finite jump of the order parameter at the transition while the free energy and its first derivative remain continuous.Comment: 12 pages, 6 figure

Dynamic facilitation explains democratic particle motion of metabasin transitions

Transitions between metabasins in supercooled liquids seem to occur through rapid "democratic" collective particle rearrangements. Here we show that this apparent homogeneous particle motion is a direct consequence of dynamic facilitation. We do so by studying metabasin transitions in facilitated spin models and constrained lattice gases. We find that metabasin transitions occur through a sequence of locally facilitated events taking place over a relatively short time frame. When observed on small enough spatial windows these events appear sudden and homogeneous. Our results indicate that metabasin transitions are essentially "non-democratic" in origin and yet another manifestation of dynamical heterogeneity in glass formers.Comment: 6 pages, 6 figure

An Efficient Simulation Environment for Modeling Large-Scale Cortical Processing

We have developed a spiking neural network simulator, which is both easy to use and computationally efficient, for the generation of large-scale computational neuroscience models. The simulator implements current or conductance based Izhikevich neuron networks, having spike-timing dependent plasticity and short-term plasticity. It uses a standard network construction interface. The simulator allows for execution on either GPUs or CPUs. The simulator, which is written in C/C++, allows for both fine grain and coarse grain specificity of a host of parameters. We demonstrate the ease of use and computational efficiency of this model by implementing a large-scale model of cortical areas V1, V4, and area MT. The complete model, which has 138,240 neurons and approximately 30 million synapses, runs in real-time on an off-the-shelf GPU. The simulator source code, as well as the source code for the cortical model examples is publicly available