The importance of leaf litter to streams is well known, as is the series of events involved in leaf decay (leaf processing). What is currently missing, however, is an understanding of how the numerous, interacting variables controlling leaf-processing rates in streams can be organized. We suggest that leaf processing is scale-dependent and that factors controlling processing rates will largely ...

Coevolutionary dynamics act on both species and their interactions in ways that shape ecological communities. It remains unclear, however, how the structure of communities at larger spatial scales influences or is influenced by local coevolutionary processes, and how mechanisms acting at these different scales feedback onto one another. Here we show that, although species interactions vary subs...

x Abstract Jets can be probed in their innermost regions (d ∼ 0.1 pc) through the study of the relativistically boosted emission of blazars. On the other extreme of spatial scales, the study of structure and dynamics of extragalactic relativistic jets received renewed impulse after the discovery, made by Chandra, of bright X-ray emission from regions at distances larger than hundreds of kpc fro...

This paper is concerned with the asymptotic behavior solutions of stochastic differential equations dyt = dωt − ∇Γ(yt)dt, y0 = 0 and d = 2. Γ is a 2 × 2 skew-symmetric matrix associated to a shear flow characterized by an infinite number of spatial scales Γ12 = −Γ21 = h(x1), with h(x1) = ∑ ∞ n=0 γnh (x1/Rn) where h n are smooth functions of period 1, hn(0) = 0, γn and Rn grow exponentially fast...

This study investigates how the performance of a set of models depends on the catchments to which these models are applied. It examines (i) whether it is possible to identify a single best model for each of the catchments, or whether results are dominated by equifinality; and (ii) whether the ranking of model performance can be related to a set of predictors, such as climate and catchment chara...

This paper is concerned with the existence and qualitative properties of transition fronts for spatially periodic reaction-diffusion equations with bistable nonlinearities. The notion of transition fronts connecting two stable steady states generalizes the standard notion of pulsating fronts. In this paper, we prove that the time-global solutions in the class of transition fronts share some com...

Several indicators have been available for evaluating the coenological-ecological status of habitats. Of these, functions that are simple to use in a standardized way are of great importance in environmental biology. One such method involves listing the genera occurring in a given habitat with large abundance and species richness. In our study, the indication power of genus-level lists of Oriba...

I describe a statistical model for natural photographic images, when decomposed in a multi-scale wavelet basis. In particular, I examine both the marginal and pairwise joint histograms of wavelet coefficients at adjacent spatial locations, orientations, and spatial scales. Although the histograms are highly non-Gaussian, they are nevertheless well described using fairly simple parameterized den...

Object descriptions used for 3D segmentation by deformable models and for statistical characterization of 3D object classes benefit from having intrinsic correspondences over deformation of the objects or multiple instances in the same object class. These correspondences apply over a variety of spatial scale levels and consequently lead to efficient segmentation and probability distributions of...

Collisional excitation of the λ21cm hyperfine transition is not strong enough to thermalize it in warm neutral (" intercloud ") interstellar gas, which we show by simultaneously solving the equations of ionization and collisional equilibrium under typical conditions. Coupling of the λ21cm excitation temperature and local gas motions may be established by the Ly-α radiation field, but only if st...