The reverse motion illusion in random dot motion displays and implications for understanding development

Across two independent developmental labs, we have been puzzled by the observation that a small proportion of our child and adult participants consistently report perceiving motion in the direction opposite to that presented in random dot motion displays, sometimes even when the motion is at 100% coherence. In this review, we first draw together existing reports of misperceptions of motion direction in random dot displays across observers in a small percentage of trials, before reporting evidence of consistent reverse motion perception in a minority of observers, including previously unreported observations from our own studies of visual development. We consider possible explanations for this reverse motion illusion, including motion induction, motion energy, correspondence noise and spatial undersampling. However, more work is required to understand the individual differences relating to this percept. We suggest that errors in perceived motion direction are likely to be more widespread than can be currently gleaned from the literature and explain why systematic study is needed, especially in children. Finally, we list some remaining open questions and call for collaborative efforts to document this phenomenon and stimulate future investigation.

Optimal deployment of the spoke of a largesized transformable reflector according to the hierarchy of criteria

The article discusses the process of controlling the angular motion of the spoke of a large-sized space-based reflector, taking into account bending vibrations. Currently, large antennas are actively used for receiving and transmitting data. When launching large structures into space, the problem arises of reliably deployment the spokes, since they are packed in a small volume to be able to be installed in a launch vehicle. Due to the possibility of various abnormal situations, such as jamming of elements, engagement of the net, it is necessary to re-deployment the antenna. Therefore, it is important to develop control algorithms that can reliably solve the problems of direct and reverse motion. In the process of deployment and bringing together the elements of the reflector, various deformations appear in the structure. When the antenna spokes are brought together, lateral oscillations make the largest contribution to the oscillatory of the transient process. Currently, elastically deformed elements are used to deployment large-sized reflectors, and a control program is also used. This prevents the control from being adjusted when the deployment conditions change. The paper investigates the possibility of minimizing the vibrations of a structure during its deployment by using optimal control algorithms in real time. The forward and reverse motion of the antenna elements is performed by means of a two-criteria hierarchy optimization. The results of numerical simulation of the optimal rotation of the reflector spoke are presented. The proposed algorithm allows you to choose the optimal control in emergency situations for various types of large reflectors.

CATALYSTS OF BARBARIZATION AND DEBARBARIZATION IN CLASSICAL ATHENS

В качестве факторов, способствовавших нарастанию варваризации в Афинах второй полвины V в. до н.э., в статье указываются создание Афинской морской державы, движение софистов, конфликт поколений, Пелопоннесская война, наступление «эры демагогов». Обратное же движение в сторону деварваризации (с самого конца Vв. до н.э.) было связано в первую очередь с возрождением уважения к законности, с укреплением стабильности и порядка. Новая афинская демократия IV в. до н.э., которую одни специалисты считают «усовершенствованным» вариантом по сравнению с демократией предшествующего столетия, а другие, напротив, ее упадком, кризисом, была в основном свободна как от охлократических, так и от олигархических тенденций; она может с полным основанием быть определена как умеренная демократия, в отличие от радикальной демократии второй половины V в. до н.э. Конфликтов не то чтобы не было, но их старались разрешать мирным путем, по возможности достигая компромисса и избегая насилия. The article cites as factors, which promoted the growth of barbarization in Athens in the last half of the 5thcentury B.C., the following ones: the emergence of the Athenian Empire, the sophistic movement, the conflict of generations, the Peloponnesian War, and the coming of the “era of demagogues”. As to the reverse motion towards debarbarization (from the very end of the 5th century B.C.), it was connected, in the first instance, with revival of the lawfulness’ authority and with strengthening order and stability. The new Athenian democracy of the 4thcentury B.C. (which is considered by some scholars an “improved” version as compared with democracy of the previous century, but by other scholars, on the contrary, its decline and crisis) was in general free from both ochlocratic and oligarchic tendencies; it may be with good reason defined as a moderate democracy, as distinct from the radical democracy of the last half of the 5thcentury B.C. It is not to say that there were no conflicts, but people sought to solve them by peaceful way, as far as possible, to reach compromises and to avoid violence.

A Novel Rotation-Structure Based Stick-Slip Piezoelectric Actuator with High Consistency in Forward and Reverse Motions

Under the same driving voltage and frequency, the forward and reverse motion inconsistency of stick-slip piezoelectric actuators would bring difficulty for subsequent control. To solve this problem, a rotation-structure based piezoelectric actuator with completely symmetric structure and two driving feet was initially proposed. By testing its output performances under various driving voltages and frequencies, it was confirmed that, although similar speeds could be achieved for forward and reverse motions, the maximum displacement and backward displacement in each step were still quite different. By analyzing the reasons leading to this difference, this actuator was further improved by using only one driving foot. The experimental results showed that the forward and reverse motion consistency of the improved actuator had been significantly improved. The deviation rate was only 1.6%, corresponding to a travel distance of 118.7 μm, obtained under the driving voltage of 100 V and driving frequency of 10 Hz. The comparison with some previously reported actuators further confirmed the advancement of this improved actuator.

Selden and Milton on Family Law

This chapter discusses the relationship between Selden and Milton on family law. Like that of the first family in paradise, it may be mutual, although not equal. Milton drew on Selden’s scholarship for his ideas about concubinage, polygamy, the church’s meddling in marriage, and especially divorce. But Selden’s ownership of two Miltonic treatises on divorce, Tetrachordon and Colasterion (1645), both of them presumably acquired while he was writing Uxor Ebraica (1646), complicates the question of influence and suggests a possible reverse motion of spirit. The chapter begins by describing some of the differences between Selden’s two discussions of family law, both cited by Milton, the primordial, universal, natural law in De Jure Naturali et Gentium and the civil law of the Jews in Uxor Ebraica. Various hints—seedlings—in Milton’s Tetrachordon might have germinated in Selden’s mind to become the majestic flowering plant that occupies the four full chapters (3.20–3) of Uxor Ebraica devoted to the key phrases on divorce in Deuteronomy 24:1 and Matthew 5:32. Milton expanded the meaning of the Bible’s word fornication to include non-sexual sins or defects. Selden, relying mainly on the Talmud, would have retrojected Miltonic ideas into the debate over divorce that he established as occurring in the first century BCE.

Numerical determination of aerodynamic characteristics of an airfoil in a ground effect

В работе изучается движение профиля над экраном на различных относительных высотах. Рассмотрены следующие методы его моделирования: условие неподвижного экрана и метод зеркального отображения для моделирования обращённого движения и условие экрана, движущегося со скоростью профиля, что моделирует прямое движение. Целью работы является выбор метода моделирования экрана, при котором обтекание профиля соответствует действительности и оценка разницы между рассмотренными методами. Задача решена в открытом пакете OpenFOAM методом контрольного объёма, где совместно решены уравнения Навье-Стокса и неразрывности, осреднённые по Рейнольдсу. Произведена верификация и валидация математической модели и найдено сеточно-независимое решение. Выбраны два профиля в плане: сегментный и симметричный. Рассмотрены несколько относительных высот. В работе построены эпюры скоростей под профилем, представлены картины обтекания профилей, исследованы их основные эксплуатационные характеристики: коэффициент подъёмной силы и коэффициент сопротивления в зависимости от относительной высоты. Построено распределение коэффициента давления по поверхности рассматриваемых профилей в зависимости от граничных условий и относительных высот. В результате анализа показано различие происходящих физических процессов при обтекании профилей в прямом и обращённом движении. Данная работа позволяет сделать вывод о том, каким образом проводить физический эксперимент для различных профилей, показывает преимущество использования метода зеркальных отображений или подвижного экрана при проведении эксперимента. In this article the movement of the profile above the screen at different relative heights is reviewed. The following methods of its modeling are considered: the condition of a stationary screen and the method of images for simulating reverse motion and the condition of a screen moving with the profile speed that simulate forward motion are considered. The aim of the work is to select a screen simulation method for a physical experiment. An open-source packet OpenFOAM based on finite-volume method is used to solve the Navier-Stokes and continuity equations averaged by Reynolds method. The mathematical model is verified and validated, and a grid-independent solution is found. Two profiles are selected: segmental and symmetrical. Several relative heights are considered. The velocitiy profiles under the airfoil are constructed, the patterns of the flow around the airfoils are presented. The dependences of coefficients on the studied parameters and the distribution of the pressure coefficient over the profile are studied and analyzed. As a result of the analysis, the difference between the physical processes when flowing around the airfoils is in forward and reverse motion is shown. This work allows us to make a conclusion about how to conduct a model experiment for various profiles, shows the advantage of using the method of images or a movable screen in the experiment.