Determination of Peierls stress from acoustic harmonic generation

The interaction of acoustic waves with dislocations leads to aperiodic oscillations in the magnitude of the acoustic nonlinearity parameter β as a function of the acoustic drive amplitude σ _ampl. The magnitude and spacing of the oscillations depend on the value of the Peierls stress. A least-square curve fit of the β(σ _ampl) equation to experimental data taken of 99.999% pure aluminum monocrystals oriented for wave propagation along the [1?0?0] crystal axis yields the value 6.2?×?10⁴?Pa for the Peierls stress. The value is consistent with the smallest values reported in the literature for aluminum where for both theoretical and experimental studies the reported values range over three orders of magnitude.     

A Unifying Principle Of Biological And Cultural Evolution And Its Implications For The Future

In this article I analyze a regular pattern in the developmental and evolutionary processes, formed by a gradual shortening of developmental stages. This shortening is the expected result of a selection process, in the biological as well as in the cultural evolutionary process. Biology and culture are in this way unified by a common mechanism. A mathematical analysis further indicates a vital condition for a continued progress of human culture, especially for a continued progressive scientific evolution, implying continued shortening of mental developmental stages by means of enhanced education.     

On the depth reversibility of point-light actions

We investigate the occurrence of perspective reversals for a depth-ambiguous point-light figure. In addition, we exploit the phenomenon of reversibility to search for stimulus features relevant in the process of depth assignment. Experiment 1 shows that perceptual switches indeed occur during prolonged viewing, although the switches occur infrequently. The reversibility is confirmed in Experiment 2, in which the perceptual ambiguity of the point-light action is manipulated as well as observers’ intention to perceive a particular alternative. In addition, the pattern of eye movements reveals local stimulus features specifically associated with the perception of the different alternatives. In Experiment 3, the importance of these features as determining factors of the initial interpretation is investigated by manipulating the location of the first fixation on the stimulus. Implications for a better understanding of biological motion perception are discussed.     

Visual impressions of generative transmission

ABSTRACT

Previous research has shown that stimuli in which a moving object (A) contacts a stationary one (B) and stops, and object B then moves off in the same direction, give rise to a causal impression: object A is perceived as producing the motion of object B. This impression is weakened or does not occur if there is a delay between A contacting B and B moving, or if there is a spatial gap between B and the location at which A stops. It is shown that a strong causal impression can occur despite the presence of both gap and delay if there are cues to generative transmission of causal influence from A to B. The cues investigated were successive colour change of a series of objects filling the gap between A and B. Reported causal impressions were stronger with the colour change stimuli than with stimuli in which the objects were present but did not change colour, and stronger if the colour change proceeded from A to B than if it proceeded in the opposite direction. Reported causal impressions increased in strength as the number of objects involved in the colour change increased, consistent with the hypothesis that the colour change is a cue to a process of transmission, and inconsistent with the hypothesis that it is perceived or inferred as involving a chain of causal relations. Other kinds of changes to object properties—a small upward motion, shrinkage without moving, and disappearance—yielded similar results. It appears that any rapid sequential change in object properties in the direction of causal influence can function to give rise to the visual impression of generative transmission. The possible role of apparent motion is discussed.     

Preattentive Perception of Multiple Illusory Line-Motion: A Formal Model of Parallel Independent-Detection in Visual Search

The phenomenon referred to as illusory line-motion (ILM; O. Hikosaka, S. Miyauchi, & S. Shimojo, 1993a) has been described as a measure of the local facilitation of attention gradient. However, J. Kawahara, K. Yokosawa, S. Nishida, and T. Sato (1996) have demonstrated a spatially parallel search for an “odd man out” in the ILM direction. Apart from showing preattentive ILM perception in terms of an analogy between line-motion and apparent motion, the authors examined whether ILM perception is possible without attention from another point of view. Four experiments revealed that the ILM target can be detected in parallel without invoking attentional facilitation and invalidated the possible contribution of attentional set in parallel ILM search. Participants were able to correctly detect the ILM target among multiple nontargets, even when the line orientation was changed from trial to trial. The authors' independent-detection model predicted ILM search performance well on several occasions. These findings strongly support a preattentive and stimulus-driven explanation of ILM perception.     

Predictive Pointing Movements and Saccades Toward a Moving Target

The authors investigated whether and, if so, how velocity information is used to control predictive manual pointing movements and saccades. Participants (N = 6) intercepted an occluded moving target as if it were still visible. They kept their eyes fixated while the target moved. The target traveled over a fixed distance and changed its velocity on the way. The presentation time of the final velocity was varied. Both the eye and the hand overshot the slow target and undershot the fast target, particularly when the duration of the final velocity was short. Thus, responses were biased in the direction of the target's initial velocity. The error seemed to arise because participants did not take their latency into account when aiming at the target. Instead, they strategically aimed farther ahead when the target was fast. Amplitude was also more related to the position of velocity change than to final velocity duration. Both findings suggest that target velocity is not extrapolated but that individuals add an increment to the position of velocity change.     

Dialogue in Our Cosmic Aloneness

The search for extraterrestrial intelligence (SETI) is briefly summarized to serve as a background for making the case that, due to the highly exceptional characteristics of the earth's position and motion in the solar system as well as the precarious history of human evolution, we may be alone in the universe. With the conviction that this cosmic isolation enhances our need for dialogue with God, I discuss the nature of authentic dialogue as exhaustively explored by Martin Buber. I conclude with remarks dealing with the importance of understanding and using Buber's insights on dialogue as a way of satisfying our primal need to communicate with a cosmic “other,” in particular, God. Thus, in contrast to the numerous articles that have discussed the theological implications of SETI being successful, I treat here what it might mean if we are alone.     

Children's justifications of plants as living things between 5 and 7 years of age

Children do not recognize plants as living things before the age of 6. In order to consider plants as part of the biological domain, children have to inhibit motion as a mandatory characteristic of life and consider other properties as well. We designed a special animated task to help us study how children's explanations about plants change during preschool. This task contained pairs of items, with unexpectedly moving plants being contrasted with motionless animals and artefacts. Children were requested to compare these pairs and to answer “why” questions. Participants were 60 typically developing children aged 5, 6 and 7. Mention of the unexpected motion of plants increased with age, while biological justifications tended to be more frequent in older children for animals only. Functional justifications were hardly ever provided and only for plant–artefact pairs. These findings contribute to a better understanding of young children's conceptions of plants.     

Exploring the Non-objectified Character of Dao in the Laozi: A Modem Articulation

This article focuses on the interpretation of heng dao 恆 道 (sometimes translated as "the constant dao") and its fundamental character in the Laozi.It argues against the prevailing interpretation of dao as an unchanging metaphysical substance or reality,and maintains that the fundamental feature of heng dao is both dynamic and eternal.Heng dao is beyond language because of its dynamic character,but the Laozi nevertheless strives to express it in three aspects:1) its flexibility and adaptability as represented in the metaphor of water;2) its movement of reversal and return;3) and in its existential significance as a guide for life.Heng dao can be called the non-objectified dao,which produces law,principle,rule,method,and so on.Looked at in this way,the dynamic character of heng dao can be called non-objective.     

Literal, fictive and metaphorical motion sentences preserve the motion component of the verb: a TMS study

We used Transcranial Magnetic Stimulation (TMS) to assess whether reading literal, non-literal (i.e., metaphorical, idiomatic) and fictive motion sentences modulates the activity of the motor system. Sentences were divided into three segments visually presented one at a time: the noun phrase, the verb and the final part of the sentence. Single pulse-TMS was delivered at the end of the sentence over the leg motor area in the left hemisphere and motor evoked potentials (MEPs) were recorded from the right gastrocnemius and tibialis anterior muscles. MEPs were larger when participants were presented with literal, fictive and metaphorical motion sentences than with idiomatic motion or mental sentences. These results suggest that the excitability of the motor system is modulated by the motor component of the verb, which is preserved in fictive and metaphorical motion sentences.