Visual Rhythm Research Articles

비쥬얼리듬을 이용한 IPTV Set-top Box 재생영상에 대한 PSNR 추정 기법

본 논문에서는 PSNR(Peak-to-peak Signal to Noise Ratio)이 다른 어떤 척도보다도 화질의 평가에 있어서 중요하다는 전제하에 비쥬얼리듬(VR: Visual Rhythm) 정보를 특징정보로 이용하여 원본영상이 가용하지 않은 일반 시청자들의 STB(Set-Top Box) 재생영상으로부터 PSNR을 추정하는 방법을 제안하였다. 핵심 아이디어는 VR정보는 근사적으로 2차원 영상프레임을 1차원으로 투영한 정보라 할 수 있기 때문에 수직성분의 화소값들로만 이루어져 있을지라도 화면특성에 관한 상당한 정보를 가지고 있기 때문에 송수신단의 VR정보만을 이용하여 PSNR값을 추정하는 것이 가능하다는 것이다. 모의실험을 통해 VR정보로부터 추정한 PSNR값이 매 프레임 별로 2차원 재생영상으로부터 구한 PSNR을 근사적으로 추정함으로써 시청자들이 평균적으로 어느 정도의 화질로 시청하고 있는지 비교적 정확하게 모니터링이 가능하다는 것을 확인하였다. 제안된 방법은 심각한 화면열화가 발생한 시간 위치와 지속시간, 발생횟수 등의 통계정보뿐 아니라 이들을 시각적으로 직접 확인할 수 있으며, 자원이 부족한 STB의 연산부담을 최소화하면서 효율적으로 영상품질을 모니터링할 수 있는 장점이 있다. In this paper, we propose a PSNR(peak-to-peak signal to noise ratio) estimation method exploiting visual rhythm information for the reconstructed video frames at the customer's STB(Set-top Box). Key idea is that we can estimate the PSNR by using VR(visual rhythm) information even though a VR consists of the pixels in a vertical direction of a 2D(2-dimensional) video frame, because VR is the 1D projected version of a 2D video frame approximately. Simulation results show that the estimated PSNR from VR information is closely related to the PSNR from 2D video frames. The advantages of the proposed scheme includes that it can monitor the video quality efficiently while minimizing the computation load of STB, and show the location, duration and occurrence count of severe picture degradation.

A Moment's Daydreaming

A Moment's Daydreaming

Sound Design is the New Score

When composer Carter Burwell, most famous for his collaboration with the Coen Brothers, said: 'I like to try to put as little music as I can in the films that I work on, and convince directors of that' (2003: 196), he possibly didn't imagine being credited in a film as musically bare as No Country for Old Men (2007), but he certainly expressed the attitude of many other composers who constantly find themselves under pressure to underscore and interpret aspects of film content that need neither emphasis nor explanation.Music in film is trying too hard these days, and even those who are not film music specialists are starting to notice it. This can be felt not only in the inevitability of scoring every action/transition/emotional/suspense scene, but also in the stubborn determination to fire all of the musical weapons all the time. So no wonder that an increasing number of composers are trying to resist this trend and convince directors to use less music in their films, knowing instinctively that this will not only benefit the film itself but also their own efforts to create effective scores.At the same time, not having music in a film does not necessarily mean condemning it to islands of dialogue surrounded by silence (not that there is anything wrong with this either, as Ingmar Bergman, Andrei Tarkovsky, Michael Haneke and many others have proved); it can also mean further expanding the approach initiated by Walter Murch, Alan Splet, David Lynch and other sound mavericks who have created imaginative, suggestive and evocative soundscapes by subverting Hollywood rules of postproduction, availing themselves of the plethora of expressive possibilities provided by an elaborate sound design. It is telling, though, that in most cases this practice has been inspired by music itself and is related to an approach to film which recognises the musical potential in the rhythmic, kinetic and affective features of a number of film's constituent elements - structuring, editing, camera movement, movement in the diegesis, speech, etc. - and which deploys them with the intention of utilising their 'musical' properties. In the context of this approach, sound has a special place not only because it carries the strongest musical potential but is also most capable of bringing out and realising this potential from film's visual components. I will illustrate this point with examples from films by Gus Van Sant and Darren Aronofsky, representative of both sides of the aesthetic divide between the shot and the cut.1Terminating his flirtation with the mainstream, Gus Van Sant's last four films were inspired by the work of European 'transcendentalist' Bela Tarr, and are driven by aesthetic adventurousness as much as by existential angst. Gerry (2002), Elephant (2003), Last Days (2004) and Paranoid Park (2007) address problems of cinematic space, time and movement in different ways, but they all have one thing in common: a contentment with cinematic 'nowness' (as opposed to a build-up to 'what comes next'). This quality inevitably reveals another dimension of the cinematic presence embodied in the 'music of here' - the sound of a place and moment which envelops and opens itself to the characters in their stillness or continuous movement.Generally more kinetic than the transcendental style usually displays,2 and thus more attentive to the array of sounds produced by or discovered through movement, Van Sant's approach often results in a particular type of audio-visual musique concrete. The most striking example of an audio-visual musical effect achieved without using any actual music happens in Gerry, in a four-minute-long scene in which Matt Damon's and Casey Affleck's characters (both called Gerry) walk beside each other through the desert, their heads bouncing in the frame, in phase, out of phase, in phase again, while the visual rhythm of their movement is accentuated by the crackling sound their boots make on the ground. It is clearly a homage to two similar scenes in Tarr's Werckmeister Harmonies (2000), but condenses their respective visual and sonic emphases into audio-visual music of continuous, rhythmic and deeply mesmerising movement. …

Light and cancer: visual impairment and circadian rhythm disturbances

Light and cancer: visual impairment and circadian rhythm disturbances

Using string matching to detect video transitions

The detection of shot boundaries in videos captures the structure of the image sequences by the identification of transitional effects. This task is important in the video indexing and retrieval domain. The video slice or visual rhythm is a single two-dimensional image sampling that has been used to detect several types of video events, including transitions. We use the longest common subsequence (LCS) between two strings to transform the video slice into one-dimensional signals obtaining a highly simplified representation of the video content. We also developed a chain of mathematical morphology operations over these signals leading to the detection of the most frequent video transitions, namely, cut, fade, and wipe. The algorithms are tested with success with various genres of videos.

The effects of visual rhythms and optic flow on stride patterns of patients with Parkinson's disease

This study was aimed at determining the effects of rhythmic visual cueing under changing visual conditions on stride frequency in patients with Parkinson's disease (PD; n=21) and healthy age matched controls ( n=7) while walking at different speeds on a treadmill. Stride frequency and stride length in patients with PD as well as controls were not rigidly coupled to walking speed and could be manipulated with walking speed as well as by using spatial and temporal rhythmic visual cues.

Visual attention in behaving cats: Attention shifts and sustained attention episodes are accompanied by distinct electrocortical activities

We analyse a particular class of fast electrocortical rhythms that occur in a limited part of the primary visual cortex (BA 18) during eye saccades in behaving cats placed in a lit environment. Their high frequency (50–132 Hz) contrasts with that of two other classes of rhythms recorded in the same cortical area, the 25–45 Hz visual rhythms (40 Hz) that we previously showed to accompany sustained focused attention, and the α rhythms (∼10 Hz), that occur in situations of rest. These “very fast visual rhythms” (VFVRs) consist of two brief successive trains, a first one of low amplitude preceding the saccade onset, and a second one, much larger, during the saccade itself. The possibility is considered, that the first train subtends a presaccadic attention shift, and the second, a change of gaze towards a new target through the interception saccade. ECoG activities can thus well distinguish between attention shift and sustained attention.

Hearing What the Eyes See

When the senses deliver conflicting information, vision dominates spatial processing, and audition dominates temporal processing. We asked whether this sensory specialization results in cross-modal encoding of unisensory input into the task-appropriate modality. Specifically, we investigated whether visually portrayed temporal structure receives automatic, obligatory encoding in the auditory domain. In three experiments, observers judged whether the changes in two successive visual sequences followed the same or different rhythms. We assessed temporal representations by measuring the extent to which both task-irrelevant auditory information and task-irrelevant visual information interfered with rhythm discrimination. Incongruent auditory information significantly disrupted task performance, particularly when presented during encoding; by contrast, varying the nature of the rhythm-depicting visual changes had minimal impact on performance. Evidently, the perceptual system automatically and obligatorily abstracts temporal structure from its visual form and represents this structure using an auditory code, resulting in the experience of "hearing visual rhythms."

Functional Brain Asymmetry and Individual Differences in Hand Preference in Early Ontogeny

This work was aimed at studying the brain mechanisms of hand preference in 10- to 11-month-old infants. According to the results of neuropsychological investigations, the preference for the right hand in children of this age (at the populational level) primarily arises in actions that demand involvement of the functions of planning and motor control of reaching (functions of the motor control of reaching: FMCR) for an object. The stage of development of the FMCR in each child was scored on the Diamond scale. Total numbers of movements performed by the right and left hands and a coefficient of the manual asymmetry (AC) were calculated. On the basis of quartile analysis of the AC distribution, groups of “right-handers,” “left-handers,” and “ambidextrals” were formed. The EEG was recorded in the state of visual focused attention, and the spectral absolute amplitude density (AAD) of the sensorimotor rhythm and other infant EEG rhythms in the α frequency band was analyzed. In order to estimate the statistical correlation of manual asymmetry, gender, and stage of development of the FMCR with functional asymmetry of the AAD of the α-band rhythms in different cortical derivations, analysis of variance with factors of repeated measurements and analysis of multiple regression were used. The main results showed that 10- to 11-month-old children with different types of manual asymmetry differed in interhemispheric asymmetry of the visual attention-related EEG α-band rhythms (including asymmetry of the sensorimotor rhythm). The maximum differences were observed in the lateral frontal and posterotemporal areas of the brain cortex. The leftward amplitude asymmetry was characteristic of right-handers; in left-handers and ambidextrals, the EEG amplitude was distributed over the brain hemispheres in a more symmetric way. The correlation between the brain and manual asymmetries was stronger in boys than in girls. There was a strict linear correlation between the degree of manual asymmetry and interhemispheric asymmetry of the EEG sensorimotor rhythm in the precentral and lateral frontal brain areas. On the whole, the close correlation of the manual asymmetry with functional asymmetry of the EEG sensorimotor rhythm suggests that it is determined by the formation of the brain FMCR lateralization.

Rhythmic movement is attracted more strongly to auditory than to visual rhythms.

People often move in synchrony with auditory rhythms (e.g., music), whereas synchronization of movement with purely visual rhythms is rare. In two experiments, this apparent attraction of movement to auditory rhythms was investigated by requiring participants to tap their index finger in synchrony with an isochronous auditory (tone) or visual (flashing light) target sequence while a distractor sequence was presented in the other modality at one of various phase relationships. The obtained asynchronies and their variability showed that auditory distractors strongly attracted participants' taps, whereas visual distractors had much weaker effects, if any. This asymmetry held regardless of the spatial congruence or relative salience of the stimuli in the two modalities. When different irregular timing patterns were imposed on target and distractor sequences, participants' taps tended to track the timing pattern of auditory distractor sequences when they were approximately in phase with visual target sequences, but not the reverse. These results confirm that rhythmic movement is more strongly attracted to auditory than to visual rhythms. To the extent that this is an innate proclivity, it may have been an important factor in the evolution of music.

Video segmentation based on 2D image analysis

The video segmentation problem consists in the identification of the boundary between consecutive shots. The common approach to solve this problem is based on dissimilarity measures between frames. In this work, the video segmentation problem is transformed into a problem of pattern detection, where each video event is transformed into a different pattern on a 2D image, called visual rhythm, obtained by a specific transformation. In our analysis we use topological and morphological tools to detect cuts. Also, we use discrete line analysis and max tree analysis to detect fade transitions and flashes, respectively. We present a comparative analysis of our method for cut detection with respect to some other methods, which shows the better results of our method.

Visual Rhythm and Shot Verification

Typical result of an automatic shot change detection algorithm expectedly includes a certain number of undetected shots as well as falsely detected shots. Even though automatic shot change detection algorithms are continuing to improve, the ultimate goal of automatically detecting all shot changes without false alarms may never be achieved. Thus, allowing a human operator to intervene—to review and verify the result of a shot change detection algorithm, to delete falsely detected shots as well as to find undetected shots—may be the most viable approach currently available for increasing the accuracy of the overall shot detection process. For this exact purpose, we propose a shot verifier based on the visual rhythm. The visual rhythm, an abstraction of the video, is a single image, a sub-sampled version of a full video in which the sampling is performed in a pre-determined and in a systematic fashion. It is a representation of the video, which includes the overall content of the video. But most importantly, the visual rhythm contains patterns or visual features that allow the viewer/operator to distinguish and classify many different types of video effects (edits and otherwise): cuts, wipes, dissolves, fades, camera motions, object motions, flashlights, zooms, etc. The different video effects manifest themselves as different patterns on the visual rhythm. Using the visual rhythm, it becomes possible, without sequentially playing the entire video, to find false positive shots as well as undetected shots. Thus, inclusion of the visual rhythm in the shot verification process will aid the operator to verify detected shots as well as to find undetected shots fast and efficiently. Our newly developed shot verifier based on the visual rhythm has been designed for operator efficiency. The design of our shot verifier presented and the usefulness of the visual rhythm during the shot verification process will be demonstrated.

Argument for the Immediate Sensuous: Notes on "Stately Mansions Did Decree and Coupling"

Brakhage's films delight and incite with a restless, unadulterated visual magnificence. Expanding the language of light, color, and visual rhythm, he takes film far beyond its usual bondage to representation and story telling. From his stomach-turning yet vital film document of autopsies, The Act of Seeing with one's own eyes (1971) to his abstract and sumptuous hand-painted Persian Series (1990s), Brakhage's works uproot established and comfortable ways of seeing. In all their manifestations, Brakhage's films call for active participation and openness from viewers, and in turn they teach us about our relation to time and perception, and introduce us to new forms of pleasure. A few years ago Brakhage put it this way: Much of my life's work constitutes an attempt to subvert the representational photography IS by creating a sense of present tense in each film's every instant of viewing (EB, 210). Brakhage's hand-painted films are a case in point, in that they demand to be experienced in a of immediate visual moments. In a five-minute film he paints and projects thousands of 16mm film frames, and though each film has its own palette and a predominant texture (inspiration), every frame is distinct, abstract and separate. Brakhage hints at solid forms, but no particular image is ever animated into coherent motion as in traditional animation. Each painting flies by at a fraction of a second, so the viewer can never up with seeing and holding all the enlarged single frames Brakhage projects to us from the screen. This multitude of disappearing paintings creates an immediate sensual experience for viewers. In Immediate Stages of the Erotic, a study of music and the sensuous erotic in human nature, Kierkegaard inadvertently illuminates an essential quality of Brakhage's hand-painted films when describing Mozart's opera Don Giovanni: The genius of sensuousness is hence the absolute subject of music. In its very essence sensuousness is absolutely lyrical, and in music it breaks forth in all its lyrical impatience. It is, namely, spiritually determined, and is, therefore, force, life, movement, unrest, succession; but this unrest, this succession, does not enrich it, it remains always the same, it does not unfold itself, but it storms uninterruptedly as if in a single breath. If I desired to characterize this lyrical quality by a single predicate, I should say: it sounds; and this brings me back again to sensuous genius as that which in its immediacy manifests itself in music. (1) Kierkegaard declared that sensuous-erotic genius demands expression in all its immediacy; and he concluded that music was the only medium appropriate for the purpose (and Mozart's Don Giovanni the most perfect rendering). But many years later Film was born, stepchild of Song and Light, and today Stan Brakhage is making films which storm uninterruptedly forward in lush luminescent music. It is the orchestration of colors, painted textures, composition, and visual tempo that constitutes the life of each work. And, though Brakhage's films are technically silent, indeed they sound in their perpetual succession and constant unrest. For all the pleasure Brakhage's painted films can deliver, they also arouse a heightened awareness of color, texture, and detail, and compel the viewer to reflect on her own thought processes. Viewers can become so hyper-aware watching that they can catch themselves spectatoring--watching the self watch (even at the cost of true engagement with) the film. The films' multi-layered effects can be so overwhelming that viewers, unable to hold onto anything familiar, might seek control through objectifying the process, guessing at technique or content: Do I see bodies? Thighs? Was that double-exposed or just layers upon layers of paint? First-time viewers may rebel in frustration. Even seasoned avant-garde film goers can find themselves in that unfortunate place of seeking something know-able to affirm that one's abilities to perceive can contend with the dominant beauty of the film's unfolding. …

Oruku Tindi Tindi: Museums and the Pseudo-Aesthetics of Primitivism

An insidious strain of primitivism is assiduously cultivating its generous plot in horticulture of Afrocentrism. Mushrooming into a metastasis, it theoretically threatens aesthetic core of study of African art with its pseudo-aesthetic dogmas. In a lecture delivered on 11 April 1997 at Wellesley College, Wole Soyinka spoke against that malignant cell of pseudo-ethnicity currently proliferating in West, under ide? ologies and rhetorics of Afrocentrism. am not an Afrocentrist, he reveals in a voice echoing his tigritude rebuke. Warning ofthe danger inherent in strain of ethnocentrism that projects and protects primitivism, in all its ramifications, as image of Africa, Soyinka specifically addressed his message to his kin in Diasporas, insisting on need to move beyond danshiki groove. His oracle should have saved some of that divination for his in situ kin, based on content ofthe above three books, two of which were written by Africans, and third of which has an image of Africa gracing its front cover, even though it was written by a European. I could picture brooding laureate, with his extravagandy white sartorial halo, breaking into following Yoruba proverb as he contemplates transAtlantic panorama of Afrocentrism and African studies: Oruku tindi tindi; Oruku tindi tindi; Oruku bigba omo, gbogbo won ya aje: Oruku, the formidable one, who mothers a zillion offsprings, and all, without exception, turn out to be witches. Oruku?of whom more will soon be divulged?apparentiy anchors these three books together in quays of Adantic ocean, from Florence to Washington, DC, to Ile-Ife. Begin with ridiculous, National Geographic-inspired Smithsonian Press cover of Museums and Community in West Africa. Behind ceramist's pendulous breasts (sucked dry by coundess babies and multiple infant mortalities) hides an ocean of texts, whose visual rhythm represents riddle of transAdantic, triangular rela? tions of last five hundred years. During that period, and with trian? gular trade, emerged a triangular aesthetic attitude, altogether nourished in disproportionate hegemonic imbalance, that links shores previously plied by slave ships. That aesthetic attitude, Atlanticism, ebbing back

The role of auditory cortex in retention of rhythmic patterns as studied in patients with temporal lobe removals including Heschls gyrus

Thisexperiment examined the participation of the auditory cortex of the temporal lobe in the perception and retention of rhythmic patterns. Four patient groups were tested on a paradigm contrasting reproduction of auditory and visual rhythms: those with right or left anterior temporal lobe removals which included Heschls gyrus (HG), the region of primary auditory cortex (RT-A and LT-A); and patients with right or left anterior temporal lobe removals which did not include HG (RT-a and LT-a). Estimation of lesion extent in HG using an MRI-based probabilistic map indicated that, in the majority of subjects, the lesion was confined to the anterior secondary auditory cortex located on the anterior-lateral extent of HG. On the rhythm reproduction task, RT-A patients were impaired in retention of auditory but not visual rhythms, particularly when accurate reproduction of stimulus durations was required. In contrast, LT-A patients as well as both RT-a and LT-a patients were relatively unimpaired on this task. None of the patient groups was impaired in the ability to make an adequate motor response. Further, they were unimpaired when using a dichotomous response mode, indicating that they were able to adequately differentiate the stimulus durations and, when given an alternative method of encoding, to retain them. Taken together, these results point to a specific role for the right anterior secondary auditory cortex in the retention of a precise analogue representation of auditory tonal patterns.

Cerebellar contributions to motor timing: a PET study of auditory and visual rhythm reproduction.

The perception and production of temporal patterns, or rhythms, is important for both music and speech. However, the way in which the human brain achieves accurate timing of perceptual input and motor output is as yet little understood. Central control of both motor timing and perceptual timing across modalities has been linked to both the cerebellum and the basal ganglia (BG). The present study was designed to test the hypothesized central control of temporal processing and to examine the roles of the cerebellum, BG, and sensory association areas. In this positron emission tomography (PET) activation paradigm, subjects reproduced rhythms of increasing temporal complexity that were presented separately in the auditory and visual modalities. The results provide support for a supramodal contribution of the lateral cerebellar cortex and cerebellar vermis to the production of a timed motor response, particularly when it is complex and/or novel. The results also give partial support to the involvement of BG structures in motor timing, although this may be more directly related to implementation of the motor response than to timing per se. Finally, sensory association areas and the ventrolateral frontal cortex were found to be involved in modality-specific encoding and retrieval of the temporal stimuli. Taken together, these results point to the participation of a number of neural structures in the production of a timed motor response from an external stimulus. The role of the cerebellum in timing is conceptualized not as a clock or counter but simply as the structure that provides the necessary circuitry for the sensory system to extract temporal information and for the motor system to learn to produce a precisely timed response.

Emergence of Shape Semantics of Architectural Shapes

In this paper we present a representation of shapes and shape semantics, and processes for the emergence of shape semantics. Constraints on the behaviours of shapes are used to define shape semantics, in particular, visual symmetry and visual rhythm. A process model of emergence of shape semantics which relies on this representation is developed. The discovery of symmetry in architectural plans is demonstrated.

Emily Dickinson: Translating Puzzling Expressions in "There's a certain Slant of light" into Japanese

Emily Dickinson:Translating Puzzling Expressions in "There's a certain Slant of light" into Japanese Michiko Iwata (bio) Click for larger view View full resolution [End Page 62] fuyu no gogo ni wa There's a certain Slant of light, nanameni sashikomu ichijoo no hikari ga aru Winter Afternoons— daiseidoo no shirabe no yoo ni That oppresses, like the Heft omoku noshikakaru Of Cathedral Tunes— seinaru kizu o owaseru Heavenly Hurt, it gives us— kizuato wa darenimo mienai We can find no scar, ga imi ga umareru tokoro But internal difference, kokoro no naka de nanika ga chigatte iru Where the Meanings, are— daremo sore o tugeru koto wa dekinai None may teach it—Any— sore wa fuuin zetsuboo 'Tis the Seal Despair— sora kara okurareta An imperial affliction shikoo no kunoo Sent us of the Air— sore ga kuru toki fuukei wa kikimimi o tate When it comes, the Landscape listens— kage wa iki o nomu Shadows—hold their breath— tachisaru toki wa tooku o mite iru When it goes, 'tis like the Distance shi'nin no booto shita kao no yoo On the look of Death— In Japan, we can read this poem in published translations by seventeen different scholars. The first translation was by Hisajiroo Noguchi in 1953. First, I must say that, in Japanese translation, you cannot appreciate Dickinson's poems in Romanized Japanese because it is only phonetic. Japanese writing is composed of ideographic characters, that is, Chinese characters, and two kinds of kana, phonetic script, hiragana and katakana. So it can be said that through combining these three elements, we can make a variety of visual rhythms to make better translations especially in poems. In translation, a difficulty is the problem of meter and alliteration and rhyme. It is rather hard or impossible to translate the music of the original lines into Japanese. But these three kinds of Japanese language are rather visual and, in a sense, substitute for rhythm in writing poems, as I have also noted in my discussion of "Further in Summer than the Birds" (P1068) in Part III (see pp. 96-100). Difficulties and Solutions Whenever I read this poem P258, I am impressed by the first two lines. They can tell all of the poem, I think. The scene is very important though this poem is written about despair. The scene also represents her feeling. The image of a winter afternoon is slow, weak, dark, heavy, and severe. In Dickinson's birthplace, Amherst, people are "sealed" in winter. They must endure the death-like season because it is given from "Heaven." It is hard to compare the climate with that of Japan, an island country which is [End Page 63] rather mild except in the northern part. But we can share the winter image well. I want to keep such an atmosphere, as we see dying winter sunlight while we listen to her serious distress even in Japanese translation. I try to make a slow and heavy rhythm with Chinese characters. The phrase "a certain Slant of light" on "Winter Afternoons" has an impact on Dickinson. Nobody except her can be depressed by it. She tries to define her depression completely. For example, "like the Heft / of Cathedral Tunes—" or "like . . . the look of Death—." She thoroughly writes her suffering from the third line in the first stanza to the end of the poem. But she does so in vain. She names her suffering "imperial affliction" because "a certain Slant of light" is sent from God in heaven, and only her imperial mind can understand it as the fundamental "affliction" in human existence. She cannot escape from it. She tries bravely to stand up to despair, like a queen. Such is her pride that it makes her expressions more powerful and noble. In translation, I take great care about the atmosphere and her poetic strategy. I try to use Chinese characters, abstract or literary styles as much as possible, which make the poem slow and heavy, in a sort of imperial way. 1. Ambiguous expressions in Dickinson But even in serious poems, she always uses some interesting expressions which puzzle her readers. It is one of her poems' special...

Diurnal Rhythmicity for Visual Sensitivity in Humans?

ABSTRACT: Visual sensitivity rhythm has been assessed by several authors in animals. It shows an intrinsic circadian rhythm of some retinal mechanisms that could account for fluctuating sensitivity to light during the day in these species. However, very little is known concerning a possible circadian rhythm of visual sensitivity in humans. The present experiment was designed to assess a diurnal rhythm of visual sensitivity using psychophysical methods. Two different detection threshold measures (adaptive and constant methods) were applied on 7 highly entrained subjects. The results show a strongly increased visual detection threshold in the morning (8:00 h) in 4 of 7 subjects, followed by an important improvement at 10:00 h, after which time it remains almost constant whatever the method used. But 3 subjects had constant thresholds throughout the day. A “first session” effect as well as a “chronotype” effect were ruled out. The results are discussed in terms of a possible effect of sleep inertia, suggesting a long-lasting effect probably dependent on the type of task.

Dynamics of pathological gait

This paper is aimed at applying tools of dynamical systems theory to the evaluation and treatment of movement disorders. A key notion in this approach is that qualitative changes in movement coordination emerge spontaneously as a result of unspecific and continuous changes in control parameters. Our research on the dynamics of gait indicates that gradually varying walking velocity as a control parameter results in systematic changes in the frequency and phase relations of arm and leg movements as well as in the phase relation of pelvic and thoratic rotation within the bipedal walking mode. Identification of these intrinsic dynamics of gait enables the classification of pathological coordination patterns. Stability and the ability to make transitions between patterns (adaptability) are important issues in the evaluation of movement disorders. For exercise therapy this implies that the patient must learn to tap the appropriate control parameter in order to facilitate spontaneous emergence of the desired coordination pattern. The use of perceptual information in the form of external auditory and visual rhythms can have positive influences on hemiplegic and Parkinsonian gait by synchronizing the movements of the body segments. The effects of rhythmic exercises are, however, very sensitive to the nature and magnitude of the rhythms manipulated. It is concluded that a systematic investigation of the role of perceptual control variables is a necessary prerequisite to understand and treat movement disorders.