Coast redwood (Sequoia sempervirens) is one of the rare conifers to reproduce successfully through clonal spread. The importance of this mode of reproduction in stand development is largely unknown. Understanding the importance of clonal spread and the spatial structure of clones is crucial for stand management strategies that would aim to maximize genetic diversity. We have developed genetic m...

An approach is presented for approximating the expected spread rate of fires that burn across 2-dimensional landscapes with random fuel patterns. The method calculates a harmonic mean spread rate across a small 2-dimensional grid that allows the fire to move forward and laterally. Within this sample grid, all possible spatial fuel arrangements are enumerated and the spread rate of an elliptical...

BACKGROUND Global warming and shifted precipitation regimes increasingly affect species abundances and distributions worldwide. Despite a large literature on species' physiological, phenological, growth, and reproductive responses to such climate change, dispersal is rarely examined. Our study aims to test whether the dispersal ability of a non-native, wind-dispersed plant species is affected b...

Endocannabinoids are diffusible lipophilic molecules that may spread to neighboring synapses. Monoacylglycerol lipase (MAGL) is the principal enzyme that degrades the endocannabinoid 2-arachidonoylglycerol (2-AG). Using knock-out mice in which MAGL is deleted globally or selectively in neurons and astrocytes, we investigated the extent to which neuronal and astrocytic MAGL limit the spread of 2...

We discuss four general features of the force-free evolution of wave packets: 1 The spatial spread of a packet changes with time in a simple way. 2 For sufficiently short durations related to the spread in the momentum of the packet the probability distribution will move with uniform speed and little change in shape. 3 After a sufficiently long time related to the initial spatial spread the wav...

SPreAD-GIS is a tool for modeling spatial patterns of anthropogenic noise propagation in natural ecosystems. SPreAD-GIS incorporates commonly available datasets on land cover, topography, and weather conditions to calculate noise propagation patterns and excess noise above ambient conditions for one-third octave frequency bands around one or multiple sound sources. User-specified noise source c...

BACKGROUND This study examines if visual attention in autism is spatially overfocused (Townsend & Courchesne, 1994) and if there is an associated deficit in broadening the spatial spread of attention. METHOD Two crosshairs were presented on each trial separated by a brief (500 ms) interval. There was a modest difference in the lengths of the two hairs in each crosshair and participants had to...

Discrete spatial heterogenity is introduced into disease transmission models, resulting in large systems of ordinary differential equations. Such metapopulation models describe disease spread on a number of spatial patches. In the first model considered, there is no explicit movement of individuals; rather infectives can pass the disease to susceptibles in other patches. The second type of mode...

The use of network models to describe the impact of local spatial structure on the spread of infections is discussed. In particular, we focus on small-world networks, within which the pattern of interactions can be varied from being entirely local to being entirely global as a single parameter is changed. Analysis approaches from graph theory, statistical physics and mathematical epidemiology a...