Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “vision transformers”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed2006

Wnt-5a mRNA translation is suppressed by the Elav-like protein HuR in human breast epithelial cells.

Wnt-5a is a non-transforming Wnt protein. Since Wnt-5a mRNA and protein levels differ within and between tumours, the potential of Wnt-5a as a prognostic factor has been debated. We have previously shown that the lack of Wnt-5a protein is a predictor of shorter disease-free survival in human breast cancer. Recently, however, we also showed that the breast tumours lacking Wnt-5a protein had a high or normal level of Wnt-5a mRNA that might explain the discrepancies in previous studies. We here report that Wnt-5a is regulated at the post-transcriptional level. The regulation was mediated by the Embryonic Lethal Abnormal Vision (ELAV)-like protein HuR, which inhibited translation of Wnt-5a when bound to highly conserved AU-rich sequences in the 3'-untranslated region (3'-UTR) of the Wnt-5a mRNA molecule, as shown by both HA-tagged Wnt-5a- and Luciferase-Wnt-5a-3'-UTR reporter assays. The HuR-dependent inhibition of Wnt-5a was supported by the fact that active HuR is located in the cytoplasm in invasive human breast tumours and that hypoxia-induced activation of HuR inhibits translation of both Luciferase-Wnt-5a-3'-UTR and endogenous Wnt-5a protein. We propose that the lack of Wnt-5a protein expression in invasive human breast tumours is caused by a HuR-mediated suppression of Wnt-5a mRNA translation.

3' Untranslated Regions↗
PubMed1980

[Ontogeny of retinal projections: observation and reflection].

Recent evidence indicates that the retinotectal projection has a field-to-field rather than a point-to-point precision. Therefore, individual fibres can vary their relative position in the fibre pathway to some extent. In addition it is not necessary that retinotopy is maintained throughout the whole pathway; transformations may also occur. In fact, in the chick embryo outgrowing retinal fibres maintain not an absolute but only a high degree of order. Transformations occur at the entrance to the optic nerve and probably also right behind the chiasm. The origin of the map is determined by the fact that central retinal fibres which are formed first connect to tectal neurons near the centre of the optic tectum where neurons mature first. There they immediately invade the cellular tectal layers and form functional synapses soon after. Supernumerary fibres degenerate.

Animals↗
PubMed2006

Representation of behaviourally relevant information by blowfly motion-sensitive visual interneurons requires precise compensatory head movements.

Flying blowflies shift their gaze by saccadic turns of body and head, keeping their gaze basically fixed between saccades. For the head, this results in almost pure translational optic flow between saccades, enabling visual interneurons in the fly motion pathway to extract information about translation of the animal and thereby about the spatial layout of the environment. There are noticeable differences between head and body movements during flight. Head saccades are faster and shorter than body saccades, and the head orientation is more stable between saccades than the body orientation. Here, we analyse the functional importance of these differences by probing visual interneurons of the blowfly motion pathway with optic flow based on either head movements or body movements, as recorded accurately with a magnetic search coil technique. We find that the precise head-body coordination is essential for the visual system to separate the translational from the rotational optic flow. If the head were tightly coupled to the body, the resulting optic flow would not contain the behaviourally important information on translation. Since it is difficult to resolve head orientation in many experimental paradigms, even when employing state-of-the-art digital video techniques, we introduce a 'headifying algorithm', which transforms the time-dependent body orientation in free flight into an estimate of head orientation. We show that application of this algorithm leads to an estimated head orientation between saccades that is sufficiently stable to enable recovering information on translation. The algorithm may therefore be of practical use when head orientation is needed but cannot be measured.

Algorithms↗
PubMed2003

The KGBR viewpoint-lighting ambiguity.

We address the visual ambiguities that arise in estimating object and scene structure from a set of images when the viewpoint and lighting are unknown. We obtain a novel viewpoint-lighting ambiguity called the KGBR that corresponds to a group of three-dimensional affine transformations on the object or scene geometry combined with transformations on the object or scene albedo. Our analysis assumes orthographic projection with an affine camera model. We include photometric cues, such as shadowing and shading, that we model using Lambertian reflectance functions with shadows (cast and attached) and multiple light sources (but no interreflections). We relate the KGBR to affine ambiguities in estimating shape and to the generalized bas-relief (GBR) ambiguity.

Humans↗
PubMed2002

Pointing movements may be produced in different frames of reference depending on the task demand.

Movements are likely guided by the nervous system in task-specific spatial frames of reference (FRs). We tested this hypothesis by analyzing fast arm pointing movements involving the trunk made to targets located within the reach of the arm. In the first experiment, subjects pointed to a motionless target and, in the second experiment, to a target moving synchronously with the trunk. Vision of the arm and targets was prevented before movement onset. Each experiment started after three to five training trials. In randomly selected trials of both experiments, an electromagnet device unexpectedly prevented the trunk motion. When the trunk was arrested, the hand trajectory and velocity profile remained invariant in an FR associated with the experimental room in the first or in an FR moving with the trunk in the second experiment. Substantial changes in the arm interjoint coordination in response to the trunk arrest were observed in the first but not in the second experiment. The results demonstrate the ability of the nervous system to rapidly adapt behavior at the joint level to transform motor performance from a spatial FR associated with the environment to one associated with the body. A theoretical framework is suggested in which FRs are considered as pre-existing neurophysiological structures permitting switching between different FRs and guiding multiple joints and muscles without redundancy problems.

Adult↗
PubMed2006

Structural anatomy of pure and hemianopic alexia.

BACKGROUND: The two most common types of acquired reading disorder resulting from damage to the territory of the dominant posterior cerebral artery are hemianopic and pure alexia. Patients with pronounced hemianopic alexia have a right homonymous hemianopia that encroaches into central or parafoveal vision; they read individual words well, but generate inefficient reading saccades when reading along a line of text. Patients with pure alexia also often have a hemianopia but are more disabled, making frequent errors on individual words; they have sustained damage to a brain region that supports efficient word identification. OBJECTIVE: To investigate the differences in lesion site between hemianopic alexia and pure alexia groups, as rehabilitative techniques differ between the two conditions. METHODS: High-resolution magnetic resonance images were obtained from seven patients with hemianopic alexia and from six patients with pure alexia caused by a left occipital stroke. The boundary of each lesion was defined and lesion volumes were then transformed into a standard stereotactic space so that regional comparisons could be made. RESULTS: The two patient groups did not differ in terms of damage to the medial left occipital lobe, but those with pure alexia had additional lateral damage to the posterior fusiform gyrus and adjacent tissue. CONCLUSIONS: Clinicians will be able to predict the type of reading disorder patients with left occipital lesions have from simple tests of reading speed and the distribution of damage to the left occipital lobe on brain imaging. This information will aid management decisions, including recommendations for reading rehabilitation.

Aged↗
PubMed2006

The spatial distribution and temporal dynamics of brain regions activated during the perception of object and non-object patterns.

Both animal and human studies suggest that the efficiency with which we are able to grasp objects is attributable to a repertoire of motor signals derived directly from vision. This is in general agreement with the long-held belief that the automatic generation of motor signals by the perception of objects is based on the actions they afford. In this study, we used magnetoencephalography (MEG) to determine the spatial distribution and temporal dynamics of brain regions activated during passive viewing of object and non-object targets that varied in the extent to which they afforded a grasping action. Synthetic Aperture Magnetometry (SAM) was used to localize task-related oscillatory power changes within specific frequency bands, and the time course of activity within given regions-of-interest was determined by calculating time-frequency plots using a Morlet wavelet transform. Both single subject and group-averaged data on the spatial distribution of brain activity are presented. We show that: (i) significant reductions in 10-25 Hz activity within extrastriate cortex, occipito-temporal cortex, sensori-motor cortex and cerebellum were evident with passive viewing of both objects and non-objects; and (ii) reductions in oscillatory activity within the posterior part of the superior parietal cortex (area Ba7) were only evident with the perception of objects. Assuming that focal reductions in low-frequency oscillations (<30 Hz) reflect areas of heightened neural activity, we conclude that: (i) activity within a network of brain areas, including the sensori-motor cortex, is not critically dependent on stimulus type and may reflect general changes in visual attention; and (ii) the posterior part of the superior parietal cortex, area Ba7, is activated preferentially by objects and may play a role in computations related to grasping.

Adult↗
PubMed1996

Psychological effect of stereoscopic 3-D images with fragrances.

Stereoscopic 3-D images are used with a lot of virtual reality systems because of their sense of reality. At the same time, in the training that heightens levels of self control of autonomic responses with images, it is thought that reality of software is important. Therefore, the authors investigated use of 3-D images as a technical tool to heighten the reality of software. In this study, a laboratory was transformed into a relaxation room using 3-D images with fragrances and an experiment was carried out to examine the psychological effect of it. From the results of this study, the authors reported on the effects of fragrances on psychological responses when viewing 3-D images and the possibilities of producing these effects for relaxation.

Adult↗
PubMed2004

Opposite visual field asymmetries for egocentric and allocentric spatial judgments.

The purpose of the present study was to investigate the relation between visual hemifields and spatial frames of reference, according to the idea that multiple representations of 3D space exist. Results from two experiments clearly show that an upper visual hemifield advantage only arises when allocentric spatial judgments are required in order to perform a location task, whereas a lower visual hemifield advantage arises when egocentric spatial judgments are required. Such a double dissociation was interpreted as due to the activity of two separate neural pathways operating specific transformations of visual input for different functional outputs: scene recognition, mostly relying on allocentric frames of reference and subserved by the ventral, occipito-temporal pathway of the visual system, and goal directed actions, mostly relying on egocentric systems and subserved by the dorsal, occipito-parietal pathway of the visual system.

Adult↗
PubMed2005

A 2020 vision of patient-centered primary care.

Patient-centered care has received new prominence with its inclusion by the Institute of Medicine as 1 of the 6 aims of quality. Seven attributes of patient-centered primary care are proposed here to improve this dimension of care: access to care, patient engagement in care, information systems, care coordination, integrated and comprehensive team care, patient-centered care surveys, and publicly available information. The Commonwealth Fund 2003 National Survey of Physicians and Quality of Care finds that one fourth of primary care physicians currently incorporate these various patient-centered attributes in their practices. To bring about marked improvement will require a new system of primary care payment that blends monthly patient panel fees with traditional fee-for-service payment, and new incentives for patient-centered care performance. A major effort to test this concept, develop a business case, provide technical assistance and training, and diffuse best practices is needed to transform American health care.

Family Practice↗
PubMed2004

[Phototherapeutic keratectomy in the treatment of lattice corneal dystrophy type I].

PURPOSE: Lattice corneal dystrophy type I is an autosomal dominant corneal dystrophy caused by allelic mutations of the BIGH3 gene. Type I dystrophy is recognized clinically by the characteristic net of linear opacities within the corneal stroma that results from an accumulation of amyloid. This study was designed to evaluate the therapeutic potential of phototherapeutic keratectomy (PTK) for the treatment of lattice corneal dystrophy type I. PATIENTS AND METHODS: PTK was performed with the Chiron Technolas Chiron Keracor 217c on a series of 19 eyes of 13 patients with lattice dystrophy type I. Mean patient age was 38.9 years. The mean follow-up period was 36 months. Localization of central opacities was determined by analyzing Scheimpflug images. The changes in spherical equivalent and best corrected visual acuity were evaluated at 1, 3, 6, 9, 12, 18, 24 and 36 months. RESULTS: The central depth of the deposits measured with the Scheimpflug camera was on average 74.14+/-31.03 microm in the primary dystrophies and 30.1+/-10 microm in graft recurrence. We noted a clear improvement in visual acuity, which increased by 0.257+/-0.120 to 0.600+/-0.178 as of the 3rd month and stabilized at 0.684+/-0.257 until the 36th month. A disappearance of repeating ulcerations was observed at month 30. We found a statistically significant correlation (R=0.6776; p=0.0109) between the improvement in vision (in lines) and the depth of opacities (with the Scheimpflug camera). The mean hyperopic shift caused by photoablation (69+/-15 microm) was +0.71+/-1 D at 36 months. CONCLUSION: These results confirm that PTK is an effective method of managing corneal lattice dystrophy type I.

Adult↗
PubMed1993

Proprioceptive guidance and motor planning of reaching movements to unseen targets.

The ability to make accurate reaching movements toward proprioceptively defined target locations was studied in seven normal subjects who were trained to reach to five different targets in a horizontal plane, with no vision of hand or target. The task consisted of moving a handle from a fixed origin to each target location, fast and accurately. Target locations were learned in training sessions that utilized acoustic cuing. Most movements were rapid, with a bell-shaped velocity profile. The error in target reproduction, which constituted the difference between the position consciously identified as the correct target location and the real target location, was calculated in each trial. This was compared with the error in preprogrammed reaching, which constituted the difference between the point in space where the initial fast movement toward the target ended and the target location. The absence of significant differences between these two error types indicated that the transformation from an internal representation of target location into a motor program for reaching to it did not introduce an additional reaching error. Learning of target locations was done only with the right hand, yet, reaching of both hands was tested. This allowed a comparison between the subjects' ability to utilize a transformed spatial code (reaching with the untrained hand) and their ability to use a direct sensory-motor code (reaching with the trained hand). While transformation of the spatial code was found to reduce it's accuracy, utilization of this code in motor programming again did not appear to introduce an additional error.

Adult↗
PubMed1997

Melanocytomas of the optic nerve and uvea.

Melanocytomas are an example of changing attitudes toward clinical management of intraocular tumors. They also might exemplify the power of pathological examination and follow-up in patient care and treatment. Prior to the observations of Zimmerman [10], most patients with melanocytomas underwent enucleation. Today, these patients are followed up conservatively and continue to enjoy vision. Melanocytomas are fairly uncommon tumors found more often in blacks and hyperpigmented individuals than in whites. Women are slightly more likely to have this tumor than are men. Melanocytomas are uniformly densely hyperpigmented lesions found on the optic nerve, choroid, ciliary body, and iris and are benign, stationary tumors that seldom cause symptoms or secondary complications. In patients with papillary melanocytomas, the most common visual disturbance is enlargement of the blind spot. With larger tumors, an afferent pupillary defect may be noted. Ciliary body and iris tumors may cause secondary anterior segment complications such as glaucoma, hyphema, or ectopia. Dispersion of pigment by melanocytomas is common and should not necessarily be interpreted as a sign of malignant transformation. Ancillary tests such as fluorescein angiography, ICG angiography, ultrasonography, CT, MRI, and the 32P test are of little clinical benefit in differentiating between melanocytomas and malignant melanomas and may lead to erroneous conclusions. Treatment for melanocytomas is conservative, its mainstay being serial clinical examinations, fundus photography, and visual field examinations to record tumor size and document growth. Lesions that grow rapidly may have transformed to a malignant melanoma and should be treated accordingly.

Combined Modality Therapy↗
PubMed2004

Visual perception of extent and the geometry of visual space.

The question of how perceived extents are related to the corresponding physical extents is a very old question that has not been satisfactorily answered. The common model is that perceived extent is proportional to the product of image size and perceived distance. We describe an experiment that shows that perceived extents are substantially larger than this model predicts. We propose a model that accounts for our results and a large set of other results. The principal assumption of the model is that, in the computation of perceived extent, the visual angle signal undergoes a magnifying transform. Extent is often perceived more accurately than the common model predicts, so the computation is adaptive. The model implies that, although the perception of location and the perception of extent are related, they not related by Euclidean geometry, nor by any metric geometry. Nevertheless, it is possible to describe the perception of location and extent using a simple model.

Humans↗
PubMed1996

Effects of changing viewing conditions on the perceived structure of smoothly curved surfaces.

Observers' perceptions of a male and a female torso were investigated using monocular and stereoscopic images under varying conditions of illumination. Observers judged the shapes of these torsos by adjusting a gauge figure to estimate the local slant and tilt at numerous probe points arranged in a lattice over the torso's surface. The results revealed that the judged surfaces in the monocular and stereoscopic conditions were related by an affine stretching transformation in depth that accounted for approximately 95% of the between-condition variance. There was also a strong affine component between the judgments obtained for the different illumination directions, although a further analysis of the residuals indicated that changing the direction of illumination influenced perceived structure in a piecewise manner.

Contrast Sensitivity↗
PubMed2001

Can the amplitude difference spectrum peak frequency explain the foveal crowding effect?

Hess et al. (Vision Res. 40 (2000) 365) found that the peak frequency of the amplitude difference spectrum (ADS) of a Landolt C/flanking bar configuration was higher than that of an isolated C. They believed that this mismatch in the dominant frequency components could account for the foveal crowding effect. The following empirical and theoretical studies were conducted to evaluate this new explanation. First, the foveal crowding effect between a Landolt C and four flanking bars was measured under same- and mixed-polarity conditions. Significant crowding was found under the mixed-polarity condition. This result is different from the data that Hess et al. used to support their explanation of the foveal crowding effect. Second, analytical expressions for the Fourier transforms of C/flanking bar configurations were derived. ADS for various ring/bar separations and contrast polarities were calculated using these expressions. This analysis showed several discrepancies between ADS peak frequency predictions and empirical data. Therefore, the ADS peak frequency of the stimulus configuration does not provide an adequate explanation for the foveal crowding effect.

Fourier Analysis↗
PubMed1994

Perceptual sensitivity maps within globally defined visual shapes.

An unsolved problem of biology is the processing of global shape in natural vision. The known processes of early vision are spatially restricted (or local) operations, and little is known about their interactions in organizing the visual image into functionally coherent (or global) objects. Here we introduce a human psychophysical method which allows us to measure the effect of perceptual organization on the activity pattern of local visual detectors. We map differential contrast sensitivity for a target across regions enclosed by a boundary. We show that local contrast sensitivity is enhanced within the boundary even for large distances between the boundary and the target. Furthermore, the locations of maximal sensitivity enhancement in the sensitivity maps are determined by global shape properties. Our data support a class of models which describe shapes by the means of a medial axis transformation, implying that the visual system extracts 'skeletons' as an intermediate-level representation of objects. The skeletal representation offers a structurally simplified shape description which can be used for higher-level operations and for coding into memory.

Contrast Sensitivity↗
PubMed1998

Hampton, Nutting, and Rival gospels at The Johns Hopkins Hospital and Training School for Nurses, 1889-1906.

PURPOSE: To examine the attempts by Isabel Hampton Robb and Mary Adelaide Nutting to reshape nurse training into an academic system of nursing education. As health care delivery undergoes transformation in the 1990s, it is useful to consider the strategies used as well as the successes and failures, of past nurse leaders. DESIGN: Historical research. METHODS: Archival data were analyzed in 1996 pertaining to the creation in 1889 and administration of the nursing school and hospital founded by Johns Hopkins in Baltimore, Maryland, USA. Events were studied using published and unpublished writings by Hampton and Nutting, as well as relevant secondary sources. FINDINGS: Separated by class from those with power, and limited by 19th century notions of women's place, Isabel Hampton Robb and Adelaide Nutting helped inaugurate nursing's quest for professionalization. Undaunted by adversity, they achieved novel accomplishments for women and nurses. Hampton and Nutting possessed vision, intelligence, the capacity to motivate, political skills, good judgement, and managerial competence. CONCLUSIONS: Hampton's and Nutting's inability to strengthen the link between the school of nursing and the Johns Hopkins University and the lack of unity within nursing limited their success. This research illuminates some of the controversies pertaining to nursing during an earlier period of sweeping health care change.

Baltimore↗