Diffuse scattering model for human brain wave (Alpha) propagation prediction during meditation inside a temple, through ray tracing, a hypothetical study

Electromagnetic radio waves have been propagating for billions of years through the universe since the beginning of time. Electromagnetic radio wave propagation and the communication revolution it spawned, however are products of the twentieth century. Radio propagation in a particular environment is a complex, multipath phenomenon which involves several different mechanisms. According to a traditional, simplified approach, two major urban propagation mechanisms are identified over-roof-top (ORT) or vertical propagation (VP), where one major radial path undergoes multiple diffractions on building tops, and lateral propagation (LP) where several rays reflect/diffract all vertical building walls/edges according to the geometrical Optics (GO) rules before reaching the receiver.

A snapshot of the earliest stages of normal fault development

Despite decades of study, models for the growth of normal faults lack a temporal framework within which to understand how these structures accumulate displacement and lengthen through time. Here, we use borehole and high-quality 3D seismic reflection data from offshore Norway to quantify the lateral (0.2-1.8 mmyr-1) and vertical (0.004-0.02 mmyr-1) propagation rates (averaged over 12-44 Myr) for several long (up to 43 km), moderate displacement (up to 225 m) layer-bound faults that we argue provide a unique, essentially ‘fossilised’ snapshot of the earliest stage of fault growth. We show that lateral propagation rates are 90 times faster than displacement rates during the initial 25% of their lifespan suggesting that these faults lengthened much more rapidly than they accrued displacement. Although these faults have slow displacement rates compared with data compiled from 30 previous studies, they have comparable lateral propagation rates. This suggests that the unusual lateral propagation to displacement rate ratio is likely due to fault maturity, which highlights a need to document both displacement and lateral propagation rates to further our understanding of how faults evolve across various temporal and spatial scales.

Incorporating Driver Relaxation into Factory Adaptive Cruise Control and its Implications on Traffic Operation

Current adaptive cruise control (ACC) systems adopt fixed desired time headway, which leads to an abrupt speed reduction after being cut-in by a lane changer in front or when changing lanes too close to the new leader. In contrast, human drivers behave differently and feature a variable spacing within 20 or 30 seconds right after a cut-in or lane change. Motivated by the smooth transition found in driver relaxation, the paper aims to incorporate relaxation into ACC systems. Based on the open-source ACC platform, Openpilot, Comma.ai, the paper proposes a feasible relaxation model compatible with current factory ACCs, which has also been tested using a market car with stock ACC hardware. The study further investigates the impact of relaxation ACC on traffic operation. Numerical simulation suggests that incorporating relaxation into ACC can help: i) reduce the magnitude of speed perturbations in both cut-in vehicles and followers; ii) stabilize the lane-changing traffic by reducing the speed variance and prevent the lateral propagation of congestion, and iii) increase the average vehicle speed and capacity in merging traffic.

The influence of laterally varying crustal strength on rift physiography – Combining 3D numerical models and geological observations

<p>Continental rifts form across a mosaic of crustal units, each unit displaying properties that reflect their own unique tectonic evolution and lithology. The physiography of rift systems is largely reflective of this underlying crustal substrate, which may change over short distances along-strike of the rift. Pervasive, well-developed structural heterogeneities represent sites where strain may localise and may thus weaken a crustal volume. In contrast, relatively pristine areas of crust, such as igneous batholiths, contain few heterogeneities and may be considered relatively strong. Characteristic rift physiographies associated with these ‘strong’ and ‘weak’ crustal units, and how rift physiography changes across areas where these units are juxtaposed remain elusive.</p><p>In this study we use the 3D thermo-mechanical numerical code ASPECT to investigate how areas of differing upper crustal strength influence rift physiography. We extend a 500x500x100km volume, within which we define four 125km wide upper crustal domains of either ‘strong’, ‘normal’ or ‘weak’ crust. Crustal strength is determined by varying the initial plastic strain in the model across 5km blocks, producing a static-like pattern. Weak domains contain weakened blocks with large initial plastic strain values, creating large contrasts with adjacent blocks. In contrast, 5 km blocks within the strong domain have relatively low values of initial plastic strain, producing little variation between adjacent blocks.</p><p>Our modelling simulations reveal that strain rapidly localises onto high-displacement structures (equivalent to faults) in the weak domain. Fault spacing and the strain accommodated by each fault decreases in the normal domain, with the strong domain characterised by closely-spaced, low displacement faults approximating uniform strain. When heterogeneities are incorporated into the strong domain, we find that these rapidly localise strain, effectively partitioning the domain into a series of smaller, strong areas separated by faults. Faults are initially inhibited at the boundaries with adjacent stronger domains; as extension progresses, these faults break through the barrier and propagate into the stronger domains.</p><p>Our observations have important implications for rift system development, particularly in areas of highly heterogeneous basement. Studies have shown that the Tanganyika rift developed at high angles to cratonic and mobile belt basement terranes, with localisation inhibted in the stronger cratonic areas. Similarly, extension in the Great South Basin (GSB), New Zealand, initially localised in weak, dominantly sedimentary, terranes, compared to stronger, more homogenous granitic areas. Terrane boundaries in the GSB also inhibit the lateral propagation of faults. Comparing our model results with observations from these and other systems globally, we determine characteristic structural styles and examine how rift physiography varies across ‘strong’ and ‘weak’ crustal volumes.</p>

Spatial variations of sills and implications for magma dispersal across the Karoo basin

Dolerite sill complexes of the Karoo Large Igneous Province (ca. 183 Ma) show systematic variations in emplacement style and size throughout the Karoo basin. These variations are explained in terms of three main, interrelated factors, namely the overburden thickness or emplacement depth, variations in host rock rigidities as a result of sedimentary facies changes in the Karoo basin, and proximity to magma feeders. In the northern parts of the thinner (<500 m) and more coarse-clastic Karoo stratigraphy, sills intrude preferentially below more rigid sandstone horizons that acted as stress barriers causing the arrest of magma ascent and lateral spreading below sandstone beds. The low overburden promotes roof uplift above sills and associated brittle faulting can initiate the formation of inclined sheets that limits the lateral propagation path of inner sills. Roof uplift is further promoted by the proximity to magma feeders in the basement and resulting variations in magma pressure that control the spreading rate and inflation of sills. Localised dyke networks spaced at regular intervals and rooted in underlying sills reflect the stretching of roof rocks above inflating sills. The combination of these effects results in relatively small (<10 km) diameters of sills in the northern parts of the basin. Sills emplaced at intermediate depths (ca. 700 m) in the central Karoo basin are marked by larger diameters (>30 km) and thicknesses of up to 100 m. This reflects the higher overburden pressures and the delay of roof failure and subsequent formation of inclined sheets. Dyke networks in the roof of these sills become more irregular and non-systematic at these greater depths. At even greater depths of up to 2 km in the southern parts of the Karoo basin, mega-sills reach diameters of 50 to 80 km, but thicknesses of only up to 35 m. Thick shale-rich sequences in the southern Karoo basin facilitate sill emplacement through internal host-rock deformation and ductile flow. The thicker overburden and different host rock rigidity delay or suppress roof failure and formation of inclined sheet, thus allowing for the lateral propagation of sills. The deeper-seated sills are typically not associated with local dyke networks.

Anticipatory responses along motion trajectories in awake monkey area V1

ABSTRACTWhat are the neural mechanisms underlying motion integration of translating objects? Visual motion integration is generally conceived of as a feedforward, hierarchical, information processing. However, feedforward models fail to account for many contextual effects revealed using natural moving stimuli. In particular, a translating object evokes a sequence of transient feedforward responses in the primary visual cortex but also propagations of activity through horizontal and feedback pathways. We investigated how these pathways shape the representation of a translating bar in monkey V1. We show that, for long trajectories, spiking activity builds-up hundreds of milliseconds before the bar enters the neurons’ receptive fields. Using VSDI and LFP recordings guided by a phenomenological model of propagation dynamics, we demonstrate that this anticipatory response arises from the interplay between horizontal and feedback networks driving V1 neurons well ahead of their feedforward inputs. This mechanism could subtend several perceptual contextual effects observed with translating objects.HighlightsOur hypothesis is that lateral propagation of activity in V1 contributes to the integration of translating stimuliConsistent with this hypothesis, we find that a translating bar induces anticipatory spiking activity in V1 neurons.A V1 model describes how this anticipation can arise from inter and intra-cortical lateral propagation of activity.The dynamic of VSDi and LFP signals in V1 is consistent with the predictions made by the model.The intra-cortical origin is further confirmed by the fact that a bar moving from the ipsilateral hemifield does not evoke anticipation.Horizontal and feedback input are not only modulatory but can also drive spiking responses in specific contexts.

Transfer of displacement between faults of opposed dip

<p>The transfer of displacement between faults that dip in the same direction is well understood and relay ramps between adjacent fault segments have been frequently described. Perhaps counterintuitively, displacement can also be transferred between faults that dip in opposite directions but the structure at the boundaries between opposed dipping faults is not well understood. We constrain the mechanism by which displacement is transferred between opposed-dipping faults by examining the geometries of faulted horizons and fault throw distributions at these ‘conjugate relay zones’.</p><p>Structure contour maps of horizons offset by overlapping opposed-dipping faults from different extensional settings display a consistent pattern. Above the line of intersection between the conjugate faults the deformed horizon is flat between converging faults and displacement transfer is reflected in changes in footwall elevation. Below the line of fault intersection the mutual footwall is flat and elevation changes occur in the hanging walls of the divergent faults. These elevation changes can be explained as a simple superposition of the deformation fields of two faults that have retarded lateral propagation due to the presence of the other synchronous fault, irrespective of whether the two faults actually intersect. The observed patterns of horizon elevation strongly resemble those seen at boundaries between adjacent basin-scale half-graben of opposed polarity.</p>

Unrest episodes at Alcedo and Cerro Azul (Galapagos) revealed by InSAR data and geodetic modelling

<p>Western Galápagos calderas experienced repeated eruptive and non-eruptive unrest in the last decades, only partially studied. Here we investigated, using the Synthetic Aperture Radar Interferometry (InSAR) and geodetic modelling, the eruptive and the non-eruptive unrest episodes occurred in two of the less studied calderas of the western Galápagos: Alcedo and Cerro Azul. Alcedo underwent repeated non-eruptive unrest from 2007 to 2011, while Cerro Azul experienced an unrest, from 2007 to 2008, culminated in two eruptive phases from May 29th to June 11th 2008. Results highlight how Alcedo experienced two episodes of uplift due to new magma injections in its shallow magma reservoir, separated by an episode with a limited lateral propagation of magma, probably interrupted for the lack of new magma supply in the magma reservoir. Results also hint to a possible relationship between these short-term unrest episodes and the longer-term process of resurgence at Alcedo. As for Cerro Azul, we overcame unwrapping errors affecting some of the InSAR data of Cerro Azul by proposing a new method, based on the wrapped phase differences among nearby pixels, to invert the wrapped phase directly. Our results highlight how the eruption was preceded by long-term pre-eruptive inflation (October 2007 – April 2008). During the first eruptive phase, most of the magma responsible for the inflation fed the lateral propagation of a radial dike, which caused a first deflation of the magmatic reservoir. During the second eruptive phase, the further lateral propagation of the dike fed a radial eruptive fissure at the base of the edifice, causing further deflation of the magmatic reservoir. From the first to the second eruptive phase, the radial dike changed its strike propagating towards a topographic low between Cerro Azul and Sierra Negra. An increase in magma supply from the reservoir to the dike promoted the further lateral propagation of the dike, confirming the importance of a continuous supply of magma in the propagation of a dike. </p>