When perception is stronger than physics: Perceptual similarities rather than laws of physics govern the perception of interacting objects

When several multistable displays are viewed simultaneously, their perception is synchronized, as they tend to be in the same perceptual state. Here, we investigated the possibility that perception may reflect embedded statistical knowledge of physical interaction between objects for specific combinations of displays and layouts. We used a novel display with two ambiguously rotating gears and an ambiguous walker-on-a-ball display. Both stimuli produce a physically congruent perception when an interaction is possible (i.e., gears counterrotate, and the ball rolls under the walker’s feet). Next, we gradually manipulated the stimuli to either introduce abrupt changes to the potential physical interaction between objects or keep it constant despite changes in the visual stimulus. We characterized the data using four different models that assumed (1) independence of perception of the stimulus, (2) dependence on the stimulus’s properties, (3) dependence on physical configuration alone, and (4) an interaction between stimulus properties and a physical configuration. We observed that for the ambiguous gears, the perception was correlated with the stimulus changes rather than with the possibility of physical interaction. The perception of walker-on-a-ball was independent of the stimulus but depended instead on whether participants responded about a relative motion of two objects (perception was biased towards physically congruent motion) or the absolute motion of the walker alone (perception was independent of the rotation of the ball). None of the two experiments supported the idea of embedded knowledge of physical interaction.

High resolution reconstructions of the Southwest Indian Ridge, 52 Ma to present: Implications for the breakup and absolute motion of the Africa plate

Summary We reconstruct the post-52 Ma seafloor spreading history of the Southwest Indian Ridge at 44 distinct times from inversions of ≈20,000 magnetic reversal, fracture zone, and transform fault crossings, spanning major regional tectonic events such as the Arabia-Eurasia continental collision, the Arabia Peninsula’s detachment from Africa, the arrival of the Afar mantle plume below eastern Africa, and the initiation of rifting in eastern Africa. Best-fitting and noise-reduced rotation sequences for the Nubia-Antarctic, Lwandle-Antarctic, and Somalia-Antarctic plate pairs indicate that spreading rates everywhere along the ridge declined gradually by ≈50 percent from ≈31 Ma to 19-18 Ma. A concurrent similar-magnitude slowdown in the component of the Africa plate’s absolute motion parallel to Southwest Indian Ridge spreading suggests that both were caused by a 31-18 Ma change in the forces that drove and resisted Africa’s absolute motion. Possible causes for this change include the effects of the Afar mantle plume on eastern Africa or the Arabia Peninsula’s detachment from the Somalia plate, which culminated at 20-18 Ma with the onset of seafloor spreading in the Gulf of Aden. At earlier times, an apparently robust but previously unknown ≈6-Myr-long period of rapid kinematic change occurred from 43 Ma to 37 Ma, consisting of a ≈50 percent spreading rate slowdown from 43-40 Ma followed by a full spreading rate recovery and 30-40 ○ clockwise rotation of the plate slip direction from 40-37 Ma. Although these kinematic changes coincided with a reconfiguration of the paleoridge geometry, their underlying cause is unknown. Southwest Indian Ridge abyssal hill azimuths are consistent with the slip directions estimated with our newly derived Somalia-Antarctic and Lwandle-Antarctic angular velocities, adding confidence in their reliability. Lwandle-Antarctica plate motion has closely tracked Somalia-Antarctic plate motion since 50 Ma, consistent with slow-to-no motion between the Lwandle and Somalia plates for much of that time. In contrast, Nubia-Somalia rotations estimated from our new Southwest Indian Ridge rotations indicate that 189±34 km of WNW-ESE divergence between Nubia and Somalia has occurred in northern Africa since 40 Ma, including 70-80 km of WNW-ESE divergence since 17-16 Ma, slow to no motion from 26-17 Ma, and 109±38 km of WNW-ESE divergence from 40 Ma to ≈26 Ma absent any deformation within eastern Antarctica before 26 Ma.

About the influence of the forces of interaction between the droplets on the dynamics of emulsion

The dynamics of deposition of compound droplets of the emulsion under the action of gravity is investigated. The interaction of the droplet with its inclusion is taken into account. Axisymmetric and asymmetric problems of deposition of compound droplets are considered. Expressions for the relative and absolute velocities of the compound emulsion droplets are found. Based on numerical modeling, the trajectories of the relative and absolute motion of the droplets are obtained.

Newton’s Scholium on Time, Space, Place and Motion

In the Scholium to the Definitions at the beginning of the Principia, Newton distinguishes absolute time, space, place, and motion from their relative counterparts. He argues that they are indeed ontologically distinct, in that the absolute quantity cannot be reduced to some particular category of the relative, as Descartes had attempted by defining absolute motion to be relative motion with respect to immediately ambient bodies. Newton’s rotating bucket experiment, rather than attempting to show that absolute motion exists, is one of five arguments from the properties, causes, and effects of motion. These arguments attempt to show that no such program can succeed, and thus that true motion can be adequately analyzed only by invoking immovable places, that is, the parts of absolute space.

SIMULATION OF NON-LINEAR CHARACTERISTICS INFLUENCE DYNAMIC ON VERTICAL RIGID GYRO ROTOR RESONANT OSCILLATIONS

The influence of viscous linear and cubic nonlinear damping of an elastic support on the resonance oscillations of a vertical rigid gyroscopic unbalanced rotor is investigated. Simulation results show that linear and cubic non-linear damping can significantly dampen the main harmonic resonant peak. In non-resonant areas where the speed is higher than the critical speed, the cubic non-linear damping can slightly dampen rotor vibration amplitude in contrast to linear damping. If linear or cubic non-linear damping increase in resonant area significantly kills capacity for absolute motion, then they have little or no influence on the capacity for absolute motion in non-resonant areas. The simulation results can be successfully used to create passive vibration isolators used in rotor machines vibration damping, including gyroscopic ones.

A Reconfigurable Multiplanar In Vitro Simulator for Real-Time Absolute Motion With External and Musculotendon Forces

Advancements in computational musculoskeletal biomechanics are constrained by a lack of experimental measurement under real-time physiological loading conditions. This paper presents the design, configuration, capabilities, accuracy, and repeatability of The University of Texas at El Paso Joint Load Simulator (UTJLS) by testing four cadaver knee specimens with 47 real-time tests including heel and toe squat maneuvers with and without musculotendon forces. The UTJLS is a musculoskeletal simulator consisting of two robotic manipulators and eight musculotendon actuators. Sensors include eight tension load cells, two force/torque systems, nine absolute encoders, and eight incremental encoders. A custom control system determines command output for position, force, and hybrid control and collects data at 2000 Hz. Controller configuration performed forward-dynamic control for all knee degrees-of-freedom (DOFs) except knee flexion. Actuator placement and specimen potting techniques uniquely replicate muscle paths. Accuracy and repeatability standard deviations across specimen during squat simulations were equal or less than 8 N and 5 N for musculotendon actuators, 30 N and 13 N for ground reaction forces (GRFs), and 4.4 N·m and 1.9 N·m for ground reaction moments. The UTJLS is the first of its design type. Controller flexibility and physical design support axis constraints to match traditional testing rigs, absolute motion, and synchronous real-time simulation of multiplanar kinematics, GRFs, and musculotendon forces. System DOFs, range of motion, and speed support future testing of faster maneuvers, various joints, and kinetic chains of two connected joints.