Some Tests of the Marr-Ullman Model of Movement Detection

Perception ◽  
1986 ◽  
Vol 15 (2) ◽  
pp. 139-155 ◽  
Author(s):  
Bernard Moulden ◽  
Helena Begg
Keyword(s):  
Sudden Onset ◽  
Homogeneous Field ◽  
Movement Detection ◽  
Contrast Polarity ◽  
Apparent Direction ◽  
Direction Of Movement ◽  
Spatially Homogeneous ◽  
The Moment ◽  
Sawtooth Waveform

Several psychophysical experiments are described which test and uphold predictions derived from the Marr–Ullman model of movement detection. First, we demonstrate the existence of adaptation which is specific not merely to the direction of movement of an edge, but also to its contrast polarity. Second, it is shown that adaptation to a spatially homogeneous field whose luminance is modulated according to a temporal sawtooth waveform produces predictable changes in sensitivity to the movement of an edge; these changes, too, are specific to particular conjunctions of direction and edge polarity. Third, similar changes in sensitivity are demonstrated to occur when the luminance of an edge is physically perturbed at the moment of its displacement. Finally, it is shown that, as predicted, the sudden onset of an edge can itself give rise to a momentary impression of movement, the apparent direction of which depends upon the change in luminance that accompanies the onset of the edge.

A Simultaneous Shift in Apparent Direction: Further Evidence for a “Distribution-Shift” Model of Direction Coding

1980 ◽  
Vol 32 (2) ◽  
pp. 325-333 ◽  
Author(s):  
George Mather ◽  
Bernard Moulden
Keyword(s):  
The Other ◽  
Movement Detection ◽  
Apparent Direction ◽  
Wide Range ◽  
Shift Model

When two superimposed moving dot fields are presented simultaneously, their axes of movement appear shifted away from each other. The shift only occurs when the two directions are within 90° of each other, and is directly comparable to that which results from adapting to one and testing on the other direction. This effect is taken as further evidence for a distribution-shift model in the direction domain. It is argued that the currently accepted model of movement detection, which restricts itself to comparisons only between oppositely-tuned direction detectors, should be elaborated to include comparisons across a very wide range of detectors.

scholarly journals The results of research to clarify the process of cutting soil spherical disk working body

2019 ◽  
pp. 30-36
Author(s):  
Volsky, V.
Keyword(s):  
Angle Of Attack ◽  
Vertical Position ◽  
Soil Medium ◽  
Operating Modes ◽  
Cutting Angle ◽  
Direction Of Movement ◽  
Soil Cutting ◽  
Instantaneous Center ◽  
The Moment ◽  
Working Bodies

Purpose. Clarify the size and direction of cutting the soil, taking into account the influence of the coordinates of the instantaneous center of the disk on the rotation of its diameter at the time of its location in a vertical position. Methods. Using the provisions of physics, theoretical mechanics and resistance of materials. Results. The influence of the coordinates of the location of the instantaneous center of the disk on the angle of cutting of the soil by the points of the blade of the disk and the vectors of their trajectory in the soil medium is established, which makes it possible to more accurately determine the value of the angle of cutting of the soil depending on the parameters and operating modes of the spherical disk working body, and its smallest possible value was used in as an evaluation criterion in the selection and justification of rational parameters and operating modes of disk harrows. It has been established that the cutting angle γcut increases with decreasing angle of inclination of the disk β and an increase in the angle of attack α'. Conclusions 1. The direction of movement of the points of the blade of the disk in the soil medium is clarified due to the rotation of the diameter of the disk at the moment of its vertical location under the influence of the coordinates of the instant center, this is confirmed by the profile of the formation of the bottom of the furrow with a notched disk of the working body. 2. A refined dependence is obtained for determining the angle of soil cutting by the points of the blade of a spherical disk working body, which combines all its parameters and the smallest possible value of the angle of soil cutting, and the expediency of its use in the selection and justification of rational parameters of the working bodies of the disk harrow. Keywords: soil, soil environment, the spherical disc working body, the points of the blade of the disk, the speed of movement of points of the blade of the disk, the cutting angle of the soil, the angle of attack, the angle of inclination of the disk to the vertical.

Thermoelectric model of the Earth's magnetic field

2021 ◽  
pp. 39-52
Author(s):  
A. N. Dmitriev ◽  
Yu. V. Pakharukov
Keyword(s):  
Magnetic Field ◽  
Inner Core ◽  
Inversion Process ◽  
Earth’S Magnetic Field ◽  
The Earth ◽  
Dipole Magnetic Field ◽  
Earth's Magnetic Field ◽  
Direction Of Movement ◽  
The Moment ◽  
Thermoelectric Model

A variant of the thermoelectric model of the Earth's dipole magnetic field is considered. It is based on geothermoelectric currents present in the planet's core. The currents cyclically change their direction, which leads over time either to warming on the Earth, if their movement is directed towards the Earth's crust, or to cooling, when moving towards the inner core. With each change in the direction of movement of the thermal currents, the poles of the Earth's magnetic field are inverted simultaneously. The inversion process is instantaneous (on the scale of planetary time) and is not the result of a gradual reversal on the 180° Earth's magnetic axis. At the moment of inversions of thermal currents in the core, the total geomagnetic field decreases to the level of 4.6∙10-6 T, which is constantly supported by thermal currents of semi-conducting rocks of the lower mantle. The considered version of the thermoelectric model of the Earth's magnetic field may be promising for studying the magnetic fields of planets in the Solar system.

scholarly journals Chest pain? Again?

CJEM ◽  
1999 ◽  
Vol 1 (01) ◽  
pp. 63
Author(s):  
Kirk Hollohan
Keyword(s):  
Chest Pain ◽  
Medical History ◽  
Sudden Onset ◽  
Smoking History ◽  
Left Shoulder ◽  
Shortness Of Breath ◽  
Past Medical History ◽  
The Moment

A 46-year-old man presented to the ED after the sudden onset of chest pain 45 minutes earlier. He had been straining (installing a fan) when the pain began. He described the pain as a severe pressure that radiated to his left shoulder and arm. No radiation to the neck or back was noted. He denied shortness of breath, nausea, diaphoresis, syncope or palpitations. He had not previously experienced similar symptoms and felt well until the moment the pain began. Past medical history included poorly controlled hypertension for 15 years and a 35 pack-year smoking history.

Light Source Position in the Perception of Object Shape

Perception ◽  
1983 ◽  
Vol 12 (4) ◽  
pp. 411-416 ◽  
Author(s):  
Kevin Berbaum ◽  
Todd Bever ◽  
Chan Sup Chung
Keyword(s):  
Light Source ◽  
Source Position ◽  
Object Shape ◽  
Apparent Direction ◽  
Accurate Perception ◽  
The Moment ◽  
Direction Opposite

The apparent relief of monocularly viewed surfaces reversed when the order of light and shade was reversed relative to the position of a lamp observed the moment earlier. The pattern of shading was reversed either by illuminating from a direction opposite to that of the apparent direction of illumination or by inverting the illuminating image relative to the light source. The combination of both of these manipulations restores the original juxtaposition of light source and shading and reestablished accurate perception of relief. These results demonstrate that the perception of the relief of physical surfaces depends upon the remembered position of an apparent light source.

scholarly journals Malignant Acanthosis Nigricans, Florid Cutaneous Papillomatosis and Tripe Palms Syndrome Associated with Gastric Adenocarcinoma - a Case Report

2015 ◽  
Vol 7 (1) ◽  
pp. 5-14
Author(s):  
Mirjana Paravina ◽  
Dragana Ljubisavljević
Keyword(s):  
Gastric Adenocarcinoma ◽  
Cancer Diagnosis ◽  
Acanthosis Nigricans ◽  
Fatal Outcome ◽  
Detailed Examination ◽  
Sudden Onset ◽  
Seborrheic Keratosis ◽  
Malignant Acanthosis Nigricans ◽  
Paraneoplastic Dermatosis ◽  
The Moment

Abstract Malignant acanthosis nigricans is a rare obligate paraneoplastic dermatosis which accounts for 20% of all acanthosis nigricans cases. The clinical features of the disease are the same as in the benign forms: symmetrical, hyperpigmented, velvety papillomatous lesions mostly involving the axillae, neck, groins, periumbilical cubital and popliteal areas, mammary areolae and less often mucous membranes. However, unlike other forms, it is characterized by sudden onset and rapid spread, commonly (80%) after the age of 40, which may be a marker of malignancy and a key to early diagnosis, indicating the need for a detailed examination. It is a disorder that has no gender differences. Most cases are detected at the moment of cancer diagnosis (61.3%), in fewer cases (about 20%) prior to cancer diagnosis, and in 21% at a later stage of malignant disease. Acanthosis nigricans is usually associated with one of the three or all three forms of paraneoplastic lesions: florid cutaneous papillomatosis, acanthosis palmaris (tripe palms, pachydermatoglyphia) involving the palms and soles, as well as multiple seborrheic keratosis (sign of Leser-Trélat). We report on a female patient with clinically established three paraneoplastic syndromes: malignant acanthosis nigricans, florid cutaneous papillomatosis, and acanthosis palmaris, which appeared before the diagnosis of advanced gastric adenocarcinoma, leading to fatal outcome.

scholarly journals Brain-Computer Interfaces for Communication: Preferences of Individuals With Locked-in Syndrome

2021 ◽  
pp. 154596832198933
Author(s):  
Mariana P. Branco ◽  
Elmar G. M. Pels ◽  
Ruben H. Sars ◽  
Erik J. Aarnoutse ◽  
Nick F. Ramsey ◽  
...  
Keyword(s):  
Development Process ◽  
Environmental Control ◽  
Control Strategies ◽  
Sudden Onset ◽  
Brain Computer Interfaces ◽  
Neural Signals ◽  
Communication Preferences ◽  
Computer Interfaces ◽  
Open Questions ◽  
The Moment

Background Brain-computer interfaces (BCIs) have been proposed as an assistive technology (AT) allowing people with locked-in syndrome (LIS) to use neural signals to communicate. To design a communication BCI (cBCI) that is fully accepted by the users, their opinion should be taken into consideration during the research and development process. Objective We assessed the preferences of prospective cBCI users regarding (1) the applications they would like to control with a cBCI, (2) the mental strategies they would prefer to use to control the cBCI, and (3) when during their clinical trajectory they would like to be informed about AT and cBCIs. Furthermore, we investigated if individuals diagnosed with progressive and sudden onset (SO) disorders differ in their opinion. Methods We interviewed 28 Dutch individuals with LIS during a 3-hour home visit using multiple-choice, ranking, and open questions. During the interview, participants were informed about BCIs and the possible mental strategies. Results Participants rated (in)direct forms of communication, computer use, and environmental control as the most desired cBCI applications. In addition, active cBCI control strategies were preferred over reactive strategies. Furthermore, individuals with progressive and SO disorders preferred to be informed about AT and cBCIs at the moment they would need it. Conclusions We show that individuals diagnosed with progressive and SO disorders preferred, in general, the same applications, mental strategies, and time of information. By collecting the opinion of a large sample of individuals with LIS, this study provides valuable information to stakeholders in cBCI and other AT development.

scholarly journals Case report: atypical recurrent painful ophthalmoplegic neuropathy

2020 ◽  
pp. 6
Author(s):  
Felipe Soares ◽  
Jorge Lapa ◽  
Bárbara Costa ◽  
Gabriel Kubota ◽  
Daniel Andrade ◽  
...  
Keyword(s):  
Clinical Manifestations ◽  
Pulse Therapy ◽  
Sudden Onset ◽  
Clinical Aspects ◽  
Oral Steroids ◽  
Neurological Exam ◽  
Cranial Mri ◽  
The Moment ◽  
Full Relief

IntroduccionRecurrent painful ophthalmoplegic neuropathy (RPON) is a rare disorder with repeated episodes of ocular cranial nerve neuropathy associated with ipsilateral headache in which secondary causes have first been excluded.Case ReportWoman, 52 years old, no comorbidity. In 2001 she presented sudden onset intense (8-10) throbbing left-sided unilateral headache that irradiated to the ipsilateral eye. The crisis lasted for 04 days, without nausea, vomit, photophobia or phonophobia. The intensity of the pain was alleviated with 1g of dipyrone and sodium naproxen in one daily oral dose of 550 mg, without analgesics excess. About two days after the end of the crisis the patient noticed left-sided palpebral ptosis and vertical diplopy preceded by retro-orbital ipsilateral twinge pain. The neurological exam showed fixed mydriasis, left-sided hypotropia and exotropia, compatible with the compromising of the 3rd ipsilateral nerve CN III. At the occasion, the patient was submitted to laboratorial exams of the cerebrospinal fluid, CT scan of the orbit and the skull, digital cerebral angiography of the four vessels, with no abnormalities. Cranial MRI showed enhanced cisternal segment of the left side third nerve. In 2004, 2006, 2008 and 2010 the patient presented the same clinical manifestations, having been treated with 1mg/kg methylprednisolone with full relief in 15 days. However, on the last episode in june of 2019, the patient presented only leftsided oculomotor manifestation, showing residual vertical diplopy after 06 months of pulse therapy. At the moment, she is taking 5 mg of Prednisone, via oral, in protocol of weaning off and ambulatorial follow up at the specialized center of cephalalgy.CommentsA case of RPON was described, diagnosed according to the ICHD-3. However, the patient presented unusual clinical aspects and age of symptoms onset. Unlike the descripitions found in literature, the first crisis occurred at the age 33. Besides, in the last event, only ocular manifestation ocurred, without cephalalgy, with persistent vertical diplopya, after pulse therapy and treatment with via oral steroids and 06 month- follow up. A case of RPON with atypical clinical manifestations and incomplete response to the treatment with steroids must be pointed out.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

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