Even as viewpoint changes with eye movements, postural changes, or self-motions, we perceive the world as stable based on the visual system’s environmental coordinate representation. It remains ...unclear which coordinate system is responsible for the contextual cueing effect, an implicit learning phenomenon for spatial arrangements. We investigated whether the contextual cueing effect is based on the environmental coordinate system or the body coordinate system when posture changes around the roll axis before and after learning. In our experiment, body position was changed between sitting and lying on one’s side before and after learning a task involving repeated visual search. The learning effect remained when the arrangement of objects was matched to the body coordinate system. Furthermore, we evaluated whether a natural image presented as a background could enhance the effect of the environmental coordinate system because it gives the spatial cue of the environment. The contextual cues that matched environmental coordinates were not used even if there is a background image; it is important that the background and contextual cues are matched to body coordinates in the learning and test phases.
We present a grain-fluid mixture for debris flows moving on a rugged (non-trivial) topography, where entrainment and deposition may take place. The model equations are derived with respect to a ...terrain-following coordinate system, which is constructed based on the topographic surface. The coordinates are fixed in space, and a “sub-topography” is added on the coordinate surface to account for the variation in the local topography when entrainment or deposition takes place. Numerical implementation is made based on a GPU-accelerated simulation tool, into which the entrainment-deposition mechanism is integrated accordingly. Two numerical examples are assigned to investigate the key features of the proposed model. One is on a horizontal plane, on which a finite mass of grain-fluid mixture is released from the state of rest. In this example, debris flow deposits significantly impact the post-event morphology and the associated flow behaviors. The other concerns a moving mass down an inclined chute merging into a horizontal deposition plane, where the levee formation is reproduced. At the end, the model is validated against grain-water experiments and applied to a large-scale historical event to evaluate its applicability.
•Entrainment is induced by basal shear stress.•Deposition primarily occurs through the sediment settling process.•A layered pattern of deposits and levee formation can be reproduced.•The model results successfully trace the areas and deposits for a large-scale event.
The human neocortex is organized radially into six layers which differ in their myelination and the density and arrangement of neuronal cells. This cortical cyto- and myeloarchitecture plays a ...central role in the anatomical and functional neuroanatomy but is primarily accessible through invasive histology only. To overcome this limitation, several non-invasive MRI approaches have been, and are being, developed to resolve the anatomical cortical layers. As a result, recent studies on large populations and structure-function relationships at the laminar level became possible. Early proof-of-concept studies targeted conspicuous laminar structures such as the stria of Gennari in the primary visual cortex. Recent work characterized the laminar structure outside the visual cortex, investigated the relationship between laminar structure and function, and demonstrated layer-specific maturation effects. This paper reviews the methods and in-vivo MRI studies on the anatomical layers in the human cortex based on conventional and quantitative MRI (excluding diffusion imaging). A focus is on the related challenges, promises and potential future developments. The rapid development of MRI scanners, motion correction techniques, analysis methods and biophysical modeling promise to overcome the challenges of spatial resolution, precision and specificity of systematic imaging of cortical laminae.
The article describes the state of the geocentric coordinate system of the Russian Federation. Current problems of the geodetic coordinate system are described, and a method for solving this problem ...is proposed.
The hydrodynamic problem of a three dimensional cone entering water in three degrees of freedom is analysed based on the incompressible velocity potential theory. The effect of horizontal motion and ...rotational motion on the entry process is investigated. The problem is solved through the boundary element method in the time domain. Two physical coordinate systems are constructed. One is the body-fixed system for the solution of fluid velocities and free surface tracking, and the other is the space-fixed system for equations of motion. To match the extremely small wetted surface at the initial stage, the former frame is stretched based on the ratio of physical coordinates and vertical travelled distance. The auxiliary function method is used to decouple the nonlinear mutual dependence between fluid loads and the body motion. Detailed results for cone motion, impact pressure and free surface are provided, and in-depth discussion on the effect of the horizontal motion and rotational motion is given.
PDF
