The interaction between the quadrupole moment of nuclear spins I > + with the electric-field-gradient (EFG) tensor leads to a splitting of the energy of the nuclear spin states. We show how the combination of laser and radio-frequency irradiation allows measurements of nuclear spin transitions in quadrupolar systems that are, in contrast to purely magnetic experiments, sensitive to the absolute...

A constrained variational deconvolution approach for multichannel images is presented. Constraints are enforced through a reparametrisation which allows a differential geometric reinterpretation. This view point is used to show that the deconvolution problem can be formulated as a standard gradient descent problem with an underlying metric that depends on the imposed constraints. Examples are g...

Introduction Diffusion MRI can give useful information on cellular structure and structural change (for a review see [1]). We show that the effective diffusion tensor obtained by mathematical homogenization theory (see e.g. [2,3]) is a good approximation to the long time apparent diffusion tensor under realistic DMR scanning conditions for both isotropic and anisotropic diffusion and general ge...

background: the purpose of this study is to demonstrate the advantages of gradient echo (gre) sequences in the detection and characterization of cerebral venous sinus thrombosis compared to conventional magnetic resonance sequences. methods: a total of 17 patients with cerebral venous thrombosis (cvt) were evaluated using different magnetic resonance imaging (mri) sequences. the mri sequences i...

Using the similarity between spacetime torsion and axial gauge couplings, we study torsional contributions to equilibrium partition function in a stationary background. In case of charged fluid minimally coupled torsion, spot existence linear magnetic vortical effects, while axial-vector current spin energy potential do not receive corrections at order. The covariant energy-momentum tensor, on ...

We solve the nonlinear evolution of pressureless, irrotational density fluctuations in a perturbed Robertson-Walker spacetime using a new Lagrangian method based on the velocity gradient and gravity gradient tensors. Borrowing results from general relativity, we obtain a set of Newtonian ordinary differential equations for these quantities following a given mass element. Using these Lagrangian ...

Weiwen Wu1,2, Yanbo Zhang2, Qian Wang2, Fenglin Liu1,3,*, Peijun Chen1 and Hengyong Yu2,* 1Key Lab of Optoelectronic Technology and Systems, Ministry of Education, Chongqing University, Chongqing 400044, China 2Department of Electrical and Computer Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA 3Engineering Research Center of Industrial Computed Tomography Nondestructive...

It has been recently shown that thalamic nuclei can be automatically segmented using diffusion tensor images (DTI) under the assumption that principal fiber orientation is similar within a given nucleus and distinct between adjacent nuclei. Validation of these methods, however, is challenging because manual delineation is hard to carry out due to the lack of images showing contrast between the ...

Fiber tract trajectories in coherently organized brain white matter pathways were computed from in vivo diffusion tensor magnetic resonance imaging (DT-MRI) data. First, a continuous diffusion tensor field is constructed from this discrete, noisy, measured DT-MRI data. Then a Frenet equation, describing the evolution of a fiber tract, was solved. This approach was validated using synthesized, n...

Recent work has outlined a framework for analyzing diffusion tensor gradient and covariance tensors in terms of invariant gradient and rotation tangents, which span local variations in tensor shape and orientation, respectively. This chapter hopes to increase the adoption of this framework by giving it a more intuitive conceptual description, as well as providing practical advice for its numeri...