25 research outputs found
Collective-coordinate analysis of inhomogeneous nonlinear Klein-Gordon field theory
Two different sets of collective-coordinate equations for solitary solutions
of Nonlinear Klein-Gordon (NKG) model is introduced. The collective-coordinate
equations are derived using different approaches for adding the inhomogeneities
as exrernal potentials to the soliton equation of motion. Interaction of the
NKG field with a local inhomogeneity like a delta function potential wall and
also delta function potential well is investigated using the presented
collective-coordinate equations and the results of two different models are
compared. Most of the characters of the interaction are derived analytically.
Analytical results are also compared with the results of numerical simulations.Comment: 16 pages, 8 figures. Accepted for publication in Volume 43 of the
Brazilian Journal of Physic
Building connectomes using diffusion MRI: why, how and but
Why has diffusion MRI become a principal modality for mapping connectomes in vivo? How do different image acquisition parameters, fiber tracking algorithms and other methodological choices affect connectome estimation? What are the main factors that dictate the success and failure of connectome reconstruction? These are some of the key questions that we aim to address in this review. We provide an overview of the key methods that can be used to estimate the nodes and edges of macroscale connectomes, and we discuss open problems and inherent limitations. We argue that diffusion MRI-based connectome mapping methods are still in their infancy and caution against blind application of deep white matter tractography due to the challenges inherent to connectome reconstruction. We review a number of studies that provide evidence of useful microstructural and network properties that can be extracted in various independent and biologically-relevant contexts. Finally, we highlight some of the key deficiencies of current macroscale connectome mapping methodologies and motivate future developments