Coherent Movement Research Articles

Accuracy, information, and response time in a saccadic decision task.

Reaction times generally follow a simple law economically described by the LATER model, in which a decision signal rises linearly in response to information about a target to a threshold at which a response is initiated, at a rate that varies from trial to trial with a Gaussian distribution. Functionally, LATER may be regarded as an ideal decision mechanism incorporating prior probability, information, and criterion level or urgency; this can be tested quantitatively by seeing whether LATER accurately predicts the effects on latency distributions of manipulating these variables: in this case, information and urgency. We presented subjects with random-dot kinematograms while fixating a central LED. The information content of the display was varied by altering the proportion of the dots moving coherently together either left or right rather than randomly. As soon as subjects detected the direction of coherent movement, they made a saccade in the same direction to one of a pair of LEDs on each side of the fixation target. Subjects responded either carefully, taking time to ensure an accurate judgement, or more hastily and with less regard for accuracy. The distributions of latencies under the different combinations of conditions were found to conform to LATER's predictions. Providing more information or increasing urgency both reduce latency; but they alter the observed distributions in different ways, equivalent to increasing the mean rate of rise on the one hand or reducing the criterion level on the other. Making only simple assumptions about the underlying mechanisms, the observed changes can be accounted for quantitatively.

Hammond Behavior versus Ground State Effects in Protein Folding: Evidence for Narrow Free Energy Barriers and Residual Structure in Unfolded States

Apparent transition state movement upon mutation or changes in solvent conditions is frequently observed in protein folding and is often interpreted in terms of Hammond behavior. This led to the conclusion that barrier regions in protein folding are broad maxima on the free energy landscape. Here, we use the concept of self-interaction and cross-interaction parameters to test experimental data of 21 well-characterized proteins for Hammond behavior. This allows us to characterize the origin of transition state movements along different reaction coordinates. Only one of the 21 proteins shows a small but coherent transition state movement in agreement with the Hammond postulate. In most proteins the structure of the transition state is insensitive to changes in protein stability. The apparent change in the position of the transition state upon mutation, which is frequently observed in φ-value analysis, is in most cases due to ground-state effects caused by structural changes in the unfolded state. This argues for significant residual structure in unfolded polypeptide chains of many proteins. Disruption of these residual interactions by mutation often leads to decreased folding rates, which implies that these interactions are still present in the transition state. The failure to detect Hammond behavior shows that the free energy barriers encountered by a folding polypeptide chain are generally rather narrow and robust maxima for all experimentally explorable reaction coordinates.

アクチン繊維・ミオシン繊維間の滑り運動揺らぎ解析 : ミオシンのコヒーレントな運動

アクチン繊維・ミオシン繊維間の滑り運動揺らぎ解析 : ミオシンのコヒーレントな運動

"a little afraid of the women of today": The Victorian New Woman and the Rhetoric of British Modernism

This essay argues that modernist British writers revived the ideologies of the Victorian New Women in their fiction and essays in order to influence the reception of radical feminism. The New Women novelists, writing at the end of the nineteenth century, developed a rhetoric of domestic feminism, a method of protofeminist subversion usually confined to the domestic space. Modernists outwardly disdained Victorian women's writing; yet they revived "the woman of the past" in their art. This seeming inconsistency within modernist sentiment actually signifies a coherent rhetorical movement that directed twentieth-century reactions to feminism and women's participation in British literary history.

The Origins of Progressive Education

By the dawn of the twentieth century, a new way of thinking about the nature of the child, classroom methods, and the purposes of the school increasingly dominated educational discourse. Something loosely called progressive education, especially its more child-centered aspects, became part of a larger revolt against the formalism of the schools and an assault on tradition. Our finest scholars, such as Lawrence A. Cremin, in his magisterial study of progressivism forty years ago, have tried to explain the origins and meaning of this movement. One should be humbled by their achievements and by the magnitude of the subject. Variously defined, progressivism continues to find its champions and critics, the latter occasionally blaming it for low economic productivity, immorality among the young, and the decline of academic standards. In the popular press, John Dewey's name is often invoked as the evil genius behind the movement, even though he criticized sugar-coated education and letting children do as they please. While scholars doubt whether any unified, coherent movement called progressivism ever existed, its offspring, progressive education, apparently did exist, wreaking havoc on the schools.

Making or Creating History?

165 MAKING OR CREATING HISTORY? Lucian Boia: Istorie si mit in constiinta româneasc � [History and Myth in the Romanian Consciousness] Bucharest: Humanitas, 2000, 384 pages THE NEED FOR FICTION ' It would not be accurate to see Lucia Boia as a representative of some kind of 'new generation' or a new school of Romanian historiography-simply because no such coherent movement exists. What exists instead is a number of contem- porary authors, who, by adopting a critical approach intended to deconstruct ideologically informed historiography, demonstrate certain common character- istics. However, the volumes written by them are individual works constituted in

Ground deformation monitoring of a potential landslide at La Palma, Canary Islands

The southern part of the island of La Palma comprises a north–south-oriented volcano known as the Cumbre Vieja. The steep gradient and high aspect ratio of the volcano, coupled with the prospect of future episodes of magma intrusion, highlight the potential for large-scale lateral collapse of the volcano, as recorded earlier in the history of La Palma and elsewhere in the Canary Islands. Historic eruptions of the Cumbre Vieja have occurred high up on the western flank of the volcano and along a single rift zone along the crest of the volcano. The geometry of the recent activity and faulting which occurred during an eruption in 1949 indicates that a discontinuity may be present beneath the western flank of the volcano, along which a future collapse may occur. To identify any displacement of the western flank overlying the discontinuity, a ground deformation network has recently been established on the volcano. The initial network spanned the fault system that developed on the upper flanks of the Cumbre Vieja during the 1949 eruption. This small network was measured in 1994, 1996 and 1997 using infrared Electronic Distance Measurement. In 1997, the network was enlarged and re-occupied, using the Global Positioning System, to incorporate the west flank and the southern part of the island. Although the results show that apparent displacements recorded during this period are within the error-margins of the techniques employed, the apparent movement vectors do suggest a coherent westward displacement of stations to the west of the 1949 fault system. Additional occupations of the network over the next few years will, however, be required to determine the reality or otherwise of this apparent coherent movement, and thus to decide whether or not the western flank of the Cumbre Vieja is currently sliding seaward. If not, it can be inferred that the volcano is stable during inter-eruptive periods.

Relationship between ventral stream for object vision and dorsal stream for spatial vision: An fMRI+ERP study

Recent imaging studies indicated the existence of two visual pathways in humans: a ventral stream for object and form vision and a dorsal stream for spatial and motion vision. The present study was motivated by a stimulating question: Supposing shape and motion are processed separately in the two pathways, how do the respective cortical areas respond to the stimuli of “forms defined by motion”? fMRI and ERP recordings were combined in order to measure the spatiotemporal activation pattern in the two pathways responding to forms defined by motion, which were produced solely by coherent movement of random dots against a background of dynamic or static random dots. The fMRI data indicated that the stimuli of forms defined by motion indeed activated both dorsal MT/V5 and ventral GTi/GF. Furthermore, the RV curves resulting from fMRI-seeded dipole modeling indicated that each pair of dipoles located at MT/V5 or GTi/GF reached the same best-fit point; a single pair of free dipoles located near the fMRI foci of MT/V5 and GTi/GF could be identified at the corresponding best-fit point; and the source waveforms resulting from fixed dipole modeling also showed simultaneous activation of MT/V5 and GTi/GF dipoles in the time interval around the best-fit point. The present results, therefore, suggest that MT/V5 and GTi/GF appear to be activated in parallel and simultaneously responding to forms defined by motion. Such findings raise interesting issues about the hierarchical organization and the functional specialization in the two pathways. Hum. Brain Mapping 8:170–181, 1999. © 1999 Wiley-Liss, Inc.

Relationship between ventral stream for object vision and dorsal stream for spatial vision: An fMRI+ERP study

Recent imaging studies indicated the existence of two visual pathways in humans: a ventral stream for object and form vision and a dorsal stream for spatial and motion vision. The present study was motivated by a stimulating question: Supposing shape and motion are processed separately in the two pathways, how do the respective cortical areas respond to the stimuli of "forms defined by motion"? fMRI and ERP recordings were combined in order to measure the spatiotemporal activation pattern in the two pathways responding to forms defined by motion, which were produced solely by coherent movement of random dots against a background of dynamic or static random dots. The fMRI data indicated that the stimuli of forms defined by motion indeed activated both dorsal MT/V5 and ventral GTi/GF. Furthermore, the RV curves resulting from fMRI-seeded dipole modeling indicated that each pair of dipoles located at MT/V5 or GTi/GF reached the same best-fit point; a single pair of free dipoles located near the fMRI foci of MT/V5 and GTi/GF could be identified at the corresponding best-fit point; and the source waveforms resulting from fixed dipole modeling also showed simultaneous activation of MT/V5 and GTi/GF dipoles in the time interval around the best-fit point. The present results, therefore, suggest that MT/V5 and GTi/GF appear to be activated in parallel and simultaneously responding to forms defined by motion. Such findings raise interesting issues about the hierarchical organization and the functional specialization in the two pathways.

Visual processing levels revealed by response latencies to changes in different visual attributes.

Visual latencies, and their variation with stimulus attributes, can provide information about the level in the visual system at which different attributes of the image are analysed, and decisions about them made. A change in the colour, structure or movement of a visual stimulus brings about a highly reproducible transient constriction of the pupil that probably depends on visual cortical mechanisms. We measured this transient response to changes in several attributes of visual stimuli, and also measured manual reaction times to the same stimulus changes. Through analysis of latencies, we hoped to establish whether changes in different stimulus attributes were processed by mechanisms at the same or different levels in the visual pathway. Pupil responses to a change in spatial structure or colour are almost identical, but both are ca. 40 ms slower than those to a change in light flux, which are thought to depend largely on subcortical pathways. Manual reaction times to a change in spatial structure or colour, or to the onset of coherent movement, differ reliably, and all are longer than the reaction time to a change in light flux. On average, observers take 184 ms to detect a change in light flux, 6 ms more to detect the onset of a grating, 30 ms more to detect a change in colour, and 37 ms more to detect the onset of coherent motion. The pattern of latency variation for pupil responses and reaction times suggests that the mechanisms that trigger the responses lie at different levels in cortex. Given our present knowledge of visual cortical organization, the long reaction time to the change in motion is surprising. The range of reaction times across different stimuli is consistent with decisions about the onset of a grating being made in V1 and decisions about the change in colour or change in motion being made in V4.

Effects of electron localisation on the magneto-optical properties of modulation doped [formula omitted] quantum wells

We study the variation of the energy of the absorption peak associated with the negatively charged exciton X− as a function of the magnetic field B. Due to a difference of cyclotron energy between an electron and X−, the absorption energy of X− is first red-shifted when B increases. It is then blue-shifted when the coherent movement of the three particles that compose X− is broken down by the high field. The detailed field dependence of line X− is correlated to the strength of the potential fluctuations in the modulation doped CdTe quantum wells.

Modernism and Revolution: Russian Literature in Transition

Reviewed by: Modernism and Revolution: Russian Literature in Transition Elizabeth Klosty Beaujour Victor Erlich. Modernism and Revolution: Russian Literature in Transition. Cambridge: Harvard UP, 1994. 314 pp. No price given. Victor Erlich is the doyen of American Slavists. His Russian Formalism: History, Doctrine (1955) familiarized a wide audience with the theories and achievements of a group whose terminology and practice have become indispensable tools for several generations of literary critics and scholars. In its revised editions, Russian Formalism remains the authoritative work on the subject. Erlich is cherished by other Slavists for his humor, his erudition, and his wisdom. A new book by him is therefore always an eagerly awaited event. Modernism and Revolution sets out to describe the encounter of Russian literary modernism with the Revolution and the Soviet era which followed. Although Erlich agrees that the great period of Russian [End Page 377] modernism was 1910–1935, he considers that “the full reach of the term may properly encompass a larger sequence, extending from the turn of the century to the immediate aftermath of the Second World War,” and so he follows the development of some writers of “the great age” beyond the beginning of the 1930s, when Soviet artistic policy aggressively stifled modernist practices. Erlich therefore employs a broad definition of modernism. He does not treat it as a coherent literary movement (which it was not, at least in Russia), but rather as a “discernible sensibility or impulse underlying and informing various disparate, indeed conflicting literary currents of the modern era” (2). He argues that these endeavors had in common an awareness of the existence of a radical break with the immediate past, “a recoil from the ‘given’ either on behalf of a more distant and more ‘usable’ past or of an ardently anticipated future” (3). Erlich distinguishes two fundamental variants of modernism: the mimetic or thematic on the one hand and the autotelic on the other. In the Russian situation, he notes: if the extremist temper of the avant-garde and its espousal of radical novelty made many of its leading figures receptive to Bolshevik rhetoric, the followers of the autotelic strand in the modernist ethos, with its emphasis on the autonomy of the literary text, tended to resist unequivocal commitment, let alone subordination to any extra-literary cause. Preoccupation with the medium, with the mode rather than the substance of expression, was clearly incompatible with the socially extrovert, instrumentalist thrust of Soviet culture. In Russia, the incompatibility between the Bolsheviks’ “single-track mentality” and the modernist proclivity for techniques of indirection such as irony and stylization, in particular the practice of “skaz,” became increasingly evident and had serious artistic and personal consequences for writers such as Babel, Zoshchenko and Zamyatin. Modernism and Revolution is divided into thirteen major chapters. “The Symbolist Ambiance” concentrates on Belyi, Blok, and Vyacheslav Ivanov. “The Futurist Rebellion” focuses on Khlebnikov and Mayakovsky. There follow “Four Masters Facing their Age” (Akhmatova, Mandel’stam, Pasternak, and Tsvetaeva), “The Battle of Manifestos,” [End Page 378] “Master and Disciple” (Zamyatin and Lunts), a chapter on two pioneers of the Soviet novel: Konstantin Fedin and Boris Pilnyak, individual chapters on Isaac Babel, Mikhail Zoshchenko, Andrey Platonov, Yury Olesha, Shklovsky and Neofuturism, llya Erenburg, and a final chapter which picks up Mayakovsky and other writers as they approached the fatidic dates of 1930 and 1932. The writers and works considered in Modernism and Revolution constitute an excellent reading list for a course on modern Russian literature, and the book’s thirteen chapter structure makes it an admirable companion to such a class. One regrets the absence of any discussion of Bulgakov (many of whose most interesting modernist works such as the play Flight and the collected stories in Diaboliad were written in the 1920s). On the other hand, it is good to see Fedin’s Cities and Years given the careful consideration which it deserves and rarely gets. Erlich’s comparison of Fedin’s novel with Victor Hugo’s Quatrevingt-treize is particularly compelling, although it leads him to underrate the importance of Marie Urbach as a source of compositional and emotional energy in Cities and Years. Erlich refers to a broad range of critical and...

Euro-Unionism and The Great Auction: An Assessment of the Prospects for the European Labour Movement Post-Maastricht

Abstract This article is concerned with the potential for the emergence of a coherent European labour movement, able to bargain at a European level with their employer counterparts. The conjuncture appears as favourable as it is likely to become, given the active support of the Commission backed by the Social Charter, the official status granted the Social Dialogue, and the activation of the Maastricht Social Protocol from November 1993. Moreover, as arguably the crucible of international unionism, the success or failure of the European movement is effectively a litmus test for international unionism more generally. To assess these matters, this article surveys the current prospects on a number of dimensions. First, it examines the strengths and weaknesses of the commitments under the Social Charter and its enactment to date. Second, it considers the Social Dialogue, and assesses progress to the present time. Third, in order to evaluate future potential, the nature of UNICE (the European employers' federa...

Seismic radiation from circular cracks growing at variable rupture velocity

AbstractWe have investigated the far-field body waves emitted by a circular fault growing at variable rupture velocity. The slip motion on the fault is constructed by assuming that the self-similar slip distribution holds at every successive instant of rupture formation for a circular crack. The present method permits us to evaluate not only the high-frequency but also the low-frequency radiation. It is also possible to handle both abrupt and continuous change in rupture velocity. The resultant expression for the radiation does not involve an integral. It is expressed in a closed form that contains information about the isochrone properties of the two extreme points having the minimum and maximum distances from the observer. Because of its simplicity and high computational speed, the present method provides us with a basic tool for simulating the radiation from seismic sources with a multitude of irregular rupture growth. The property of acceleration pulse radiated by continuous change in rupture velocity has been investigated. The time duration of the velocity change is assumed to be short but to take a finite time. The shape of the rupture front that is effective in radiating the high-frequency radiation is presumed to be semicircular. The acceleration pulse demonstrates a directivity with respect to both the pulse width and amplitude. The pulse width is, on average, given by the duration of the velocity change, and it is modulated by the directivity factor, which depends on the rupture velocity averaged over the change in rupture velocity. The pulse width radiated toward the growth direction of the semi-circular rupture front is shorter than that radiated toward the opposite side. The spectral amplitude of the acceleration pulse depends linearly on the strain, the radius of the rupture front at which the rupture velocity starts to change, the magnitude of the change in rupture velocity, and the generalized radiation pattern coefficient. The directivity of the radiation pattern coefficient is stronger than that for the case of an abrupt change in rupture velocity. In the case where the rupture stops completely, the radiation pattern coefficient is simply controlled by the magnitude of the change in rupture velocity. If we deal with a partial drop of the rupture velocity, however, we must consider the average rupture velocity as well to fully describe the radiation pattern. A procedure is presented for retrieving the model parameters from acceleration pulse data. The present results with regard to the acceleration pulse do not require the coherent movement of the rupture front over the entire circle. The results are applicable to more general cases where the rupture front moves coherently over a certain restricted segment, though the range of the segment has to become wider as the duration of the change in rupture velocity increases.

Population Policy and Feminist Political Action in Three Developing Countries

This paper reviews the impact of womens political action on population family planning and health policies during the 1980s in Brazil Nigeria and the Philippines. These cases share similar processes of democratization and economic crises but differ in region population policies demographic processes and levels of womens political mobilization. The countries studied have all undergone a process of democratization which allows the examination of womens political action under evolving conditions of popular participation. The case studies reveal different configurations of feminist political activism. An active and explicitly feminist movement is in place in Brazil which capitalizes upon its political support for the democratic coalition which defeated the military regime. Nigerian women are organized into multiple associations but lack a coherent womens movement. They have been largely reactive to the new national population policy but with little effect. Finally the nascent womens movement in the Philippines is effectively protecting womens access to family planning services from conservative forces.

Dynamics of CS2 in the large spectral bandwidth stimulated Rayleigh-wing scattering

A theoretical model for the large bandwidth stimulated Rayleigh-wing scattering [D. Wang and G. Rivoire, J. Chem. Phys. 98, 9279 (1993)] has been built, based on the existence of a translational coherent collective movement driven by an intense optical field. Its rise and decay times deduced from the comparison with the experimental spectral observation are as short as 115 fs.

Novelties in the heavens: rhetoric and science in the Copernican controversy

In this fascinating work, Jean Dietz Moss shows how the scientific revolution begun by Copernicus brought about another revolution as well one in which rhetoric, previously used simply to explain scientific thought, became a tool for persuading a skeptical public of the superiority of the Copernican system. Moss describes the nature of dialectical and rhetorical discourse in the period of the Copernican debate to shed new light on the argumentative strategies used by the participants. Against the background of Ptolemy's Almagest, she analyzes the gradual increase of rhetoric beginning with Copernicus's De Revolutionibus and Galileo's Siderius nuncius, through Galileo's debates with the Jesuits Scheiner and Grassi, to the most persuasive work of all, Galileo's Dialogue. The arguments of the Dominicans Bruno and Campanella, the testimony of Johannes Kepler, and the pleas of Scriptural exegetes and the speculations of John Wilkins furnish a counterpoint to the writings of Galileo, the centerpiece of this study. The author places the controversy within its historical frame, creating a coherent narrative movement. She illuminates the reactions of key ecclesiastical and academic figures figures and the general public to the issues. Blending history and rhetorical analysis, this first study to look at rhetoric as defined by sixteenth- and seventeenth-century participants is an original contribution to our understanding of the use of persuasion as an instrument of scientific debate.

Geological evidence for a global tectonic polarity

Inferences about plate motions over the past 40 Ma, based on structural and geodetic data, suggest that there is a coherent movement direction on a global scale. Moreover a ‘westward’ drift of the lithosphere relative to the asthenosphere is indicated by plate motions in the hot-spot reference frame. Independent geological observations such as the different styles of deformation in thrust belts associated with subduction following or opposing the relative ‘eastward or northeastward’ mantle flow also support this global tectonic polarity. Unfortunately most hot-spot reference frames are based on assumptions which strongly limit their validity. For example, many combine magmatic sources originating from different depths in the mantle, including hot-spots located along oceanic ridges which are not fixed relative to one another. Using a hot-spot reference frame filtered to exclude shallow hot-spots and anomalous ‘wet-spots’, we would predict a much higher relative ‘westward’ drift of the lithosphere. Plate motions are not random, rather that they are controlled by the relative motion between lithosphere and asthenosphere, and by gradients in lithospheric thickness and composition.Triangular shaped plates may experience rotations resulting from differential drag at the base of the lithosphere with respect to the asthenosphere (e.g. the clockwise rotation of South America). Plates appear to follow an undulatory pattern of motion on a global scale and their poles of rotation fall into a main cone located near the Earth’s rotation poles. Plate rotations induced by triangular shape, differential basal drag or lithospheric anisotropies along subduction zones may generate the scattered distribution of Euler poles. This might have inhibited the recognition of a coherent global tectonic pattern.

Three-dimensional scroll waves organize Dictyostelium slugs.

To test the hypothesis that periodic signals and chemotaxis direct later morphogenesis in Dictyostelium discoideum, we investigated cell behavior and cell movement in slugs. Trails of neutral red-stained prestalk and anterior-like cells were recorded by high-resolution digital image processing. Neutral red-stained anterior-like cells in the prespore zone of slugs move straight forward in the direction of slug migration and, furthermore, show coherent periodic cell movement. In contrast, cells in the prestalk zone move along completely different trajectories. Prestalk cells move perpendicular to the direction of slug migration; that is, they rotate around the tip. The cell movement data show that the chemotactic signal in the slug propagates as a three-dimensional scroll wave in the prestalk zone and as a planar wave in the prespore zone. The different behavior of prestalk and prespore cells is most likely caused by a difference in the oscillatory properties of the two cell types. We provide evidence that the slug stage of Dictyostelium behaves like an excitable system and that a (twisted) scroll wave organizes slug formation and migration.

Visual persistence of figures defined by relative motion

In order to measure visual persistence of figures that were solely defined by relative motion (motion-defined figures or motion figures), random-dot kinematograms were used to form stimulus figures in the two-frame, missing element task introduced by Di Lollo, V. (1977 Nature, 257, 241-243). Experiment 1 showed that motion-defined figures persisted for about 130 msec after the termination of the stimulus presentation (i.e. after the dots stopped moving). This was similar to but several tens of milliseconds longer than the visual persistence of figures which were defined by a luminance difference (luminance-defined figures or luminance figures) in the same random-dot pattern. Since motion detectors are not found in the retina or lateral geniculate in primates, our results strongly suggest that visual persistence is not only a retinal phenomenon but also a cortical one. Experiment 2 investigated the possible influence of motion aftereffects on the visual persistence of motion figures. The results showed that coherent movement of the dots over the whole display after the stimulus offset did not reduce the visual persistence of motion figures, suggesting that the source of this persistence is not a motion aftereffect. In Experiment 3, visual persistence for the motion-defined figures was shown to be longer than that for luminance-defined figures independently of the contrast of the stimulus figure as long as the stimuli could be seen clearly enough. This suggests that different mechanisms are involved in the visual persistence of motion-defined and luminance-defined figures.