Constancy Of Direction Research Articles

Quality as strategy, the evolution of co-production in the Region Jönköping health system, Sweden: a descriptive qualitative study

BackgroundPursuing the vision ‘for a good life in an attractive region,’ the Region Jönköping County (RJC) in Sweden oversees public health and health-care services for its 360 000 residents. For more than three decades, RJC has applied ‘quality as strategy,’ which has included increasing involvement of patients, family and friends and citizens. This practice has evolved, coinciding with the growing recognition of co-production as a fundamental feature in health-care services. This study views co-production as an umbrella term including different methods, initiatives and organizational levels. When learning about co-production in health-care services, it can be helpful to approach it as a dynamic and reflective process.ObjectiveThis study aims to describe the examples of key developmental steps toward co-production as a system property and to highlight ‘lessons learned’ from a Swedish health system’s journey.MethodThis qualitative descriptive study draws on interviews with key stakeholders and on documents, such as local policy documents, project reports, meeting protocols and presentations. Co-production initiatives were defined as strategies, projects, quality improvement (QI) programs or other efforts, which included persons with patient experience and/or their next of kin (PPE). We used directed manifest content analysis to identify initiatives, timelines and methods and inductive conventional content analysis to capture lessons learned over time.ResultsThe directed content analyses identified 22 co-production initiatives from 1997 until today. Methods and approaches to facilitate co-production included development of personas, storytelling, person-centered care approaches, various co-design methods, QI interventions, harnessing of PPEs in different staff roles, and PPE-driven improvement and networks. The lessons learned included the following aspects of co-production: relations and structure; micro-, meso- and macro-level approaches; attitudes and roles; drivers for development; diversity; facilitating change; new perspectives on current work; consequences; uncertainties; theories and outcomes; and regulations and frames.ConclusionsCo-production evolved as an increasingly significant aspect of services in the RJC health system. The initiatives examined in this study provide a broad overview and understanding of some of the RJC co-production journey, illustrating a health system’s approach to co-production within a context of long-standing application of QI and microsystem theories. The main lessons include the constancy of direction, the strategy for improvement, engaged leaders, continuous learning and development from practical experience, and the importance of relationships with national and international experts in the pursuit of system-wide health-care co-production.

Some Approximate Solutions of the Dynamic Problem of Axisymmetric Shock Deformation of a Previously Unstressed Incompressible Elastic Medium

Approximate theoretical solutions are presented for the boundary value problem of the shock load on the boundary of a circular cylindrical cavity in the space occupied by an incompressible elastic medium undeformed previously. We assume that the shock load causes the movement of the medium particles along helical trajectories. Data on the types and velocities of shock waves are based on the analysis of the dynamic conditions for the compatibility of discontinuities; and these conditions are supplemented by the relations along the characteristic directions. We show that the leading front of the dynamic process in an undeformed previously medium is a plane-polarized shock wave which is simultaneously included in one of the families of characteristics. This property results in the constancy of shear direction on the plane-polarized shock wave. This condition makes it possible to significantly simplify the obtaining of approximate theoretical solutions for the near-front neighborhood of the shock wave. The two approximate solutions of the problem are presented. One of them bases on solving a system of evolutionary equations that was obtained using the matched asymptotic expansions method; and the second solution, on a version of the ray method.

Delineating the perceived ground surface from a direction constancy rule

Delineating the perceived ground surface from a direction constancy rule

Visual direction constancy across eyeblinks

When a visual target is displaced during a saccade, the perception of its displacement is suppressed. Its movement can usually only be detected if the displacement is quite large. This suppression can be eliminated by introducing a short blank period after the saccade and before the target reappears in a new location. This has been termed the blanking effect and has been attributed to the use of otherwise ignored extraretinal information. We examined whether similar effects occur with eyeblinks and other visual distractions. We found that suppression of displacement perception can also occur due to a blink (both immediately prior to the blink and during the blink), and that introducing a blank period after a blink reduces the displacement suppression in much the same way as after a saccade. The blanking effect does not occur when other visual distractions are used. This provides further support for the conclusion that the blanking effect arises from extraretinal signals about eye position.

Flight Directions in the Migratory Butterfly Pieris brassicae: Results from Semi‐natural Experiments

AbstractA recently developed experimental set‐up has been used to test the constancy of flight direction in the large white butterfly Pieris brassicae, originally collected in Northern Germany. The flight direction, tested with virgin females, depends on the developmental mode. Butterflies from diapause pupae fly north, those from subitan pupae fly south.The constancy of the flight direction has been examined in detail with the spring generation over a period of 14d. The preferred direction does not change with advancing age and is essentially not influenced by temperature or by the sun's azimuth. The flight activity, however, increases with temperature, but this is concealed by an intrinsic response resulting in a diurnal peak of flight activity at 10.00–11.00 hours, long before the maximum temperature of the day is reached.Whether the observed direction can be considered as a parameter of migration behaviour is discussed. It is shown that migration in Pieris brassicae does not end with reproductive maturity but lasts throughout the entire imaginal stage.

Further Observations of “Linking” of Atrial Excitation During Clinical Atrial Fibrillation

The objective of this article was to look for evidence of nonrandom behavior during atrial fibrillation by examining long (> 15 minutes) recordings. We have previously reported transient "linking" of atrial activation during atrial fibrillation, and showed that activation was not entirely random. Over the few episodes of linking seen during 1 minute, activation directions apparently repeated, indicating a possible anatomical or physiological constraint. In the present study, we examined atrial fibrillation over longer time periods to see if this constancy of direction was stable. Endocardial recordings were made from 12 patients with atrial fibrillation using a catheter with three orthogonal bipoles, allowing measurements of local activation directions in three dimensions. The direction was calculated using Pipberger's half-area method, and episodes of transient linking were identified. An average direction for each episode of linking was calculated and plotted in two dimensions using spherical coordinates (altitude and azimuth). In addition, the nature of initiation and termination of linking was examined. Of the twelve patients, 611 episodes of linking (range 1 to 169 per patient, mean 51) were identified. The episodes for most patients clustered closely in direction. In contrast, directions measured for all activations (i.e., linked and not linked) filled up the entire available range. Linking in most cases subjectively appeared to initiate and terminate suddenly. The results indicate that the local anatomy, pathology, or physiology of the atrium has a strong constraining effect on the electrical activations occurring during atrial fibrillation, and revises our perception of activation during atrial fibrillation as "random." The demonstration that local properties greatly influence conduction during fibrillation has important implications for ablation or pacing therapy.

Control of remembered reaching sequences in monkey. I. Activity during movement in motor and premotor cortex.

Motor and premotor cortex firing patterns from 307 single neurons were recorded while monkeys made rapid sequences of three reaching movements to remembered target buttons arrayed in two-dimensional space. A primary goal was to study and compare directionally tuned responses for each of three movement periods during 12 movement sequences that uniformly sampled the directional space in front of the monkey. The majority of neurons showed maximal responses during movements in a preferred direction with smaller increases during movements close to the preferred direction. These responses showed a statistically significant regression fit to a cosine function for 72% of the neurons examined. Comparisons among tuning directions computed separately for the first, second, and third movement periods suggested the near constancy of preferred direction across a rapidly executed series of movements even though these movements began at different starting points in space. Although directionally tuned neurons were only broadly tuned for a specific direction of movement, the neuronal ensemble carried accurate directional information. A population vector computed by summing vector contributions from the entire population of tuned neurons predicted movement direction with a mean accuracy of 20 degrees. This population code made consistent predictions for each of the 36 movements that were studied using a single set of population parameters. Most of the remaining neurons (24%) that were not tuned during movement did show significant changes in activity during other aspects of task performance. Some nontuned neurons had nondirectional increases that were sustained during movement, while others showed identical phasic bursts during the three movement periods. These nontuned neurons may control stabilizations of the shoulder, trunk, and forearm during movement, or forearm movements during button pushing.

Suppression of motion during saccades

We identify two aspects of the problem of maintaining perceptual stability despite an observer's eye movements. The first, visual direction constancy, is the (egocentric) stability of apparent positions of objects in the visual world relative to the perceiver. The second, visual position constancy, is the (exocentric) stability of positions of objects relative to each other. We analyze the constancy of visual direction despite saccadic eye movements. Three information sources have been proposed to enable the visual system to achieve stability: the structure of the visual field, proprioceptive inflow, and a copy of neural efference or outflow to the extraocular muscles. None of these sources by itself provides adequate information to achieve visual direction constancy; present evidence indicates that all three are used. Our final question concerns how information processing operations result in a stable world. The three traditionally suggested means have been elimination, translation, or evaluation. All are rejected. From a review of the physiological and psychological evidence we conclude that no subtraction, compensation, or evaluation need take place. The problem for which these solutions were developed turns out to be a false one. We propose a calibration solution: correct spatiotopic positions are calculated anew for each fixation. Inflow, outflow, and retinal sources are used in this calculation: saccadic suppression of displacement bridges the errors between these sources and the actual extent of movement.

The role of exocentric reference frames in the perception of visual direction

One classic piece of evidence for an efference copy signal of eye position is that a small, positive afterimage viewed in darkness is perceived to move with the eye. When a small stationary reference point is visible the afterimage appears to move relative to the reference point. However, this is true only when the afterimage is localized to a small area. We have observed that when an extended afterimage of a complex scene is generated by a brief, bright flash it does not appear to move, even with large changes in eye position. When subjects were instructed to maintain their direction of gaze, we observed small saccades (typically < 1 deg) and slow drift movements often totalling more than 10 deg over a 30 sec period. When the instructions were to simply inspect the extended afterimage, subjects made larger saccades (up to 5 deg) which were not accompanied by afterimage movement. The smaller movements observed under the first instructions are greater than those observed in the dark or with small afterimages. When a visible reference is present with these large afterimages, the afterimage appears stationary, while the reference point appears to move. Eye position was monitored following the generation of such afterimages. In general, the perceived motion of the stationary reference point was in a direction opposite to the motion of the eye. Similar drift movements of smaller magnitude were observed with localized afterimages, but the motion was attributed to the afterimage. This suggests that with whole scene afterimages, extraretinal information about slow movements and small to moderate saccades is absent or suppressed, and that stationarity is assigned to the complex scene. This indicates a perceptual disposition to rely on visual information (when it is available) for maintaining constancy of visual direction, despite substantial changes in eye position. We found that changes in gaze as large as 13 deg produced no change in reported position of the large scene afterimage. When a small, stationary reference light was present it appeared to move in the afterimage scene in a way consistent with the recorded eye movements. When observers attempted to maintain their direction of gaze, most of the eye movements were slow drift, with occasional small saccades. When the instruction to hold gaze was relaxed, larger saccades up to about 5 deg were observed which were not accompanied by afterimage movement.

A theory of visual stability across saccadic eye movements

AbstractWe identify two aspects of the problem of maintaining perceptual stability despite an observer's eye movements. The first, visual direction constancy, is the (egocentric) stability of apparent positions of objects in the visual world relative to the perceiver. The second, visual position constancy, is the (exocentric) stability of positions of objects relative to each other. We analyze the constancy of visual direction despite saccadic eye movements.Three information sources have been proposed to enable the visual system to achieve stability: the structure of the visual field, proprioceptive inflow, and a copy of neural efference or outflow to the extraocular muscles. None of these sources by itself provides adequate information to achieve visual direction constancy; present evidence indicates that all three are used.Our final question concerns how information processing operations result in a stable world. The three traditionally suggested means have been elimination, translation, or evaluation. All are rejected. From a review of the physiological and psychological evidence we conclude that no subtraction, compensation, or evaluation need take place. The problem for which these solutions were developed turns out to be a false one. We propose a “calibration” solution: correct spatiotopic positions are calculated anew for each fixation. Inflow, outflow, and retinal sources are used in this calculation: saccadic suppression of displacement bridges the errors between these sources and the actual extent of movement.

Direction Constancy in the Oculomotor System

Whenever a visual image moves across the retina, the brain is faced with a dilemma: Did the image move because an object in the environment (or the environment itself) changed location or because the eyes changed location with respect to a stable environment? If the brain compares the retinal positions of individual objects within the visual image and finds that only one moved with respect to the others, then it can reasonably assume that the retinal motion was caused by motion of the object and not of the eyes. (This comparison of an object's position with the positions of other objects is known as exocentric, or allocentric, localization.) But how does the brain react to this dilemma when the entire visual image moves, whether the image is a fully structured scene or merely a single object In otherwise complete darkness? LJnder these conditions, exocentric localization techniques fail, and the brain must rely on its ability to localize the objects with respect to itself, the observer. For this egocentric localization, the brain must combine information concerning the retinal location of the visual im-

Saccadic suppression and the dual mechanism theory of direction constancy

Saccadic suppression and the dual mechanism theory of direction constancy

Constancy of egocentric visual direction.

Two experiments investigating the constancy of egocentric visual direction were conducted. In Experiment 1, subjects indicated when a briefly exposed light was subjectively straight ahead during various degrees of asymmetric convergence. The results indicated that the perception of direction exhibited systematic underconstancy. The departures from constancy were dependent upon the degree of asymmetric convergence, increasing as asymmetric convergence increased. Experiment 2 investigated the source of underconstancy found in Experiment 1. The results showed that the underconstancy was due to a combination of the misregistration of eye position and misregistration of the retinal location stimulated. The errors due to misregistration of retinal area were constant regardless of location of the test target, while the errors due to misregistration of eye position were dependent upon the degree of asymmetric convergence. The results were interpreted as supporting a “taking-into-account” model of visual direction.

Two kinds of adaptation in the constancy of visual direction and their different effects on the perception of shape and visual direction

Adaptation in the constancy of visual direction can be obtained under two radically different conditions, called eye-movement adaptation and field adaptation. Adaptation resulting from these conditions and from a “normal” condition was measured with a newly developed estimation test. Eye-movement adaptation was found to cause an alteration of compensatory eye movements. It apparently consists of a changed evaluation of eye movements, as demonstrated by two different pointing tests. A form test where the shape of a large oblong is set to look square also confirmed this interpretation. After field adaptation, a pointing test did not register a change, but an adaptation effect could be measured with a forward direction test. This test and a square test where no eye movements were permitted proved to be specific to field adaptation; they measured no effect after eye-movementadaptation. The normal adaptation condition Was apparently equivalent to the eye-movement adaptation condition. Its effect could be measured only with a pointing test. When we changed the normal adaptation condition so that frequent saccades were made during head turning, strong effects were measured with the two tests that were specific to field adaptation.

Two kinds of adaptation in the constancy of visual direction

Adaptation in the constancy of visual direction had previously been obtained by causing a large or a small visible area representing the environment to be objectively displaced in dependence on head movements. No stationary objects were permitted to be visible. Now experiments are reported in which displacements of a large patterned field, with the subject fixating a stationary mark in its center, led to adaptation. In these experiments, objective displacements of the environment were given by image displacements on the retina. Adaptation also resulted when the large field was stationary and only the fixation mark was displaced. Here the objective displacement was given by the rate of pursuit eye movements.

Extraretinal information in corrective saccades and inflow vs outflow theories of visual direction constancy

In Experiment I, with and without visual feedback, corrective movements were observed that were truly corrective in that their magnitude and direction were highly correlated with that of error after the main saccade and they significantly reduced discrepancy between eye and target. It was concluded that during dysmetria, there is a discrepancy between two high fidelity extraretinal signals, a reference input to the oculomotor nuclei (outflow) which corresponds to the intended eye position, and a feedback signal (inflow) which encodes actual eye position. Experiment II showed that during dysmetria, apparent visual direction is determined by an extraretinal signal that encodes actual rather than intended eye position. The two experiments taken together supported an Inflow over an Outflow theory of visual direction constancy. It was concluded further that there are at least two potential sources of inflow, muscular feedback or internal monitoring, which are consistent with data often cited in favor of Outflow Theory.

Dasht-e Baȳaz Fault, Iran: Earthquake and Earlier Related Structures in Bed Rock

An 18-km-long segment of bed rock of the Dasht-e Baȳaz earthquake fault was studied in detail to define the 1968 earthquake-related and earlier tectonic deformations. Ground displacements that accompanied the earthquake coincided precisely with the pre-existing east-trending fault trace. Maximum components of offset were 4 m left-lateral and 1 m south side relatively down. The bedrock displacement occurred along new tension fractures that strike on average at 50°, as well as along reactivated pre-existing structures. Earlier tectonic deformation also produced tension fractures (post-Pliocene), conjugate shears (Pliocene), and tension joints (pre-Pliocene), and all are consistent with 47° to 55° tectonic compression. The study covered three points: (1) the 40° to 45° angle measured between the major principal stress direction indicated by the earthquake fractures and the fault; (2) the apparent constancy of the stress field direction during the three early phases and the 1968 deformation; and (3) the “gap” and “anti-Riedel” structure shown by the overall fault trace, which, we suggest, are characteristic of situations of kinematic restraint and are associated with a nonuniformly propagating rupture.

Changes in auditory localization during body tilt.

The induction of an error between a subject's true orientation and his registered orientation in relation to gravity results in auditory mislocaliza-tions of a similar size and time course. The presence of visual cues prevents the development of errors in the interpretation of posture and, accordingly, prevents the development of errors in auditory localization as well. These observations are interpreted as evidence for a spatial reference system responsible for the maintenance of auditory and visual direction constancy. They demonstrate that where a subject hears a sound is dependent not only on the auditory cues at his ears but also on his registered orientatinn in relation to the gravitational force. vector.

Constancy and illusion of apparent direction of rotary motion in depth: Tests of a theory

An explanation of apparent direction of rotary motion in depth derived from a general theory of perceptual constancy and illusion is proposed with experimental data in its support. Apparent direction of movement is conceived of as exhibiting-perceptual constancy or illusion as a function of apparent direction of orientation m depth for plane objects and apparent relative depth for three-dimensional objects. Apparent reversals of movement direction represent either regular fluctuations between constancy and illusion of direction as a function of valid and invalid stimuli for orientation, or irregular and random fluctuations in their absence. In three preliminary experiments, the apparent movement direction of plane ellipses was investigated as a function of surface pattern information for orientation, and in Experiment I apparent reversals during 20-revolution trials were studied. In Experiment II, apparent movement direction of 3D elliptical V shapes as a function of surface pattern information for relative depth was investigated. In addition to supporting the explanation proposed, the data offer a resolution of a conflict between different theories of apparent reversal of motion in depth.

Dental arch depth and width studied longitudinally from 12 years of age to adulthood

This investigation was designed to study dental arch depth and arch width in male and female subjects from the age of 12 years to adulthood. Arch depth and width measurements were taken from dental casts of twenty-six subjects at annual intervals from 12 to 17 years of age and at an additional examination of these subjects after they had reached the age of 23 years. The age range of the subjects at the time of the additional examination was 23.2 years to 30.1 years. The mean age was 26.3 years. All subjects were North American Caucasians with acceptable occlusion. Summarily, selected findings are as follows: 1. 1. Means for both maxillary and mandibular arch depth decrease with age throughout the period studied in each sex, with the rate of change being less after the age of 15 years. The mean decrease in mandibular arch depth from 12 to 26 years of age was 3.2 mm. for male subjects, or approximately a 10 per cent decrease. For female subjects, mean decrease in arch depth was 2.6 mm., or approximately a 9 per cent decline. 2. 2. For female subjects, means for arch width in each arch revealed no significant change during the 14-year span from 12 to 26 years of age. In males there was a small statistically significant increase in arch width from 12 to 15 years of age. 3. 3. Every person in the study showed a decrease in arch depth after the age of 15 years. The range of decrease in the mandibular arch for the period from 15 to 26 years of age was 0.1 mm. to 2.3 mm. For the same age group, 92 per cent of the decreases were in excess of 0.75 mm. and 46 per cent of the decreases were in excess of 1.25 mm. 4. 4. No evidence was found to reject the null hypothesis of no sex difference in mean change in arch depth for any of the age intervals studied. 5. 5. A moderate negative association (r = −0.55) was found between (a) arch depth decrease from 12 to 14 years of age and (b) arch depth decrease from 14 to 26 years of age. 6. 6. Individual comparisons of four subjects were presented, demonstrating the constancy of direction but variability in amount of arch depth decrease from age 12 to early adulthood.