By identifying the effect of any parameter such as distance, attenuation and scattering on the Line Spread Function (LSF), one can compensate the quantitative and qualitative destructive effect of such parameters by deconvolution method. Using a 99mTC line source, this study was performed on a single head ADAC SPECT system operating in planar mode. Variation of FWTM and FWHM and LSFs as a...

Living in unstable habitats is expected to decrease the intensity of isolation by distance in populations through the need for frequent movements of individuals. Insects associated with fruiting bodies of fungi therefore are supposed to have weak spatial genetic structure of populations compared with those living in more stable habitats. With the use of an amplified fragment length polymorphism...

A Wishart model is proposed for random distance matrices in which the components are correlated gamma random variables, all having the same degrees of freedom. The marginal likelihood is obtained in closed form. Its use is illustrated by multidimensional scaling, by rooted tree models for response covariances in social survey work, and unrooted trees for ancestral relationships in genetic appli...

Distance matrices are matrices whose elements are the relative distances between points located on a certain manifold. In all cases considered here all their eigenvalues except one are non-positive. When the points are uncorrelated and randomly distributed we investigate the average density of their eigenvalues and the structure of their eigenfunctions. The spectrum exhibits delocalized and str...

We consider distance matrices of certain graphs and of points chosen in a rectangular grid. Formulae for the inverse and the determinant of the distance matrix of a weighted tree are obtained. Results concerning the inertia and the determinant of the distance matrix of an unweighted unicyclic graph are proved. If D is the distance matrix of a tree, then we obtain certain results for a perturbat...

Over the past decade, Euclidean distance matrices, or EDMs, have been receiving increased attention for two main reasons. The first reason is that the many applications of EDMs, such as molecular conformation in bioinformatics, dimensionality reduction in machine learning and statistics, and especially the problem of wireless sensor network localization, have all become very active areas of res...

The role of species' interactions in structuring biological communities remains unclear. Mutualistic symbioses, involving close positive interactions between two distinct organismal lineages, provide an excellent means to explore the roles of both evolutionary and ecological processes in determining how positive interactions affect community structure. In this study, we investigate patterns of ...