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At least 307 records · Page 17Linked to original sources
PubMed2005

HVS-based medical image compression.

INTRODUCTION: With the promotion and application of digital imaging technology in the medical domain, the amount of medical images has grown rapidly. However, the commonly used compression methods cannot acquire satisfying results. METHODS: In this paper, according to the existed and stated experiments and conclusions, the lifting step approach is used for wavelet decomposition. The physical and anatomic structure of human vision is combined and the contrast sensitivity function (CSF) is introduced as the main research issue in human vision system (HVS), and then the main designing points of HVS model are presented. On the basis of multi-resolution analyses of wavelet transform, the paper applies HVS including the CSF characteristics to the inner correlation-removed transform and quantization in image and proposes a new HVS-based medical image compression model. RESULTS: The experiments are done on the medical images including computed tomography (CT) and magnetic resonance imaging (MRI). At the same bit rate, the performance of SPIHT, with respect to the PSNR metric, is significantly higher than that of our algorithm. But the visual quality of the SPIHT-compressed image is roughly the same as that of the image compressed with our approach. Our algorithm obtains the same visual quality at lower bit rates and the coding/decoding time is less than that of SPIHT. CONCLUSIONS: The results show that under common objective conditions, our compression algorithm can achieve better subjective visual quality, and performs better than that of SPIHT in the aspects of compression ratios and coding/decoding time.

Algorithms↗
PubMed1986

An economic evaluation of "Health for All".

The World Health Organization's 'Global Strategy' is an ambitious vision, but to achieve its goals it must first be implemented. Implementation will require careful and detailed planning. This paper evaluates the possibilities of transforming the Global Strategy from a laudable policy initiative into an actual 'Plan for Health', from the point of view of a health economist. This economic evaluation assesses the probable costs of implementing various activities of the Strategy, and the likelihood that developing countries will be able to afford these costs, either on their own, or with the assistance of the developed countries. A final section considers the current global situation and presents trends over the last two decades. The numbers of countries that have already achieved the goals of the Strategy, that can be expected to achieve the goals of the Strategy by the year 2000, and that are unlikely to achieve these goals (on the basis of current trends) are shown. The WHO 'success indicator' based on numbers of countries is compared to a more epidemiological one based on deciles of the world's population. It is argued that, even several years after the initiation of the Global Strategy, insufficient information exists on the next logical step of transforming the Policy into a Plan. Unless adequate attention is paid to this vital step, implementation of the Strategy will inevitably be ad hoc and patchy. Further research on the costs of the activities proposed by the Global Strategy, and the probable effects on health of those activities, is desperately needed.

Data Collection↗
PubMed1996

Learning to care, for a healthier tomorrow.

Despite the fundamental transformations occurring in health care, academic medicine can maintain, and actually enhance, its value to society. But to do so will require a shared vision of where academic medicine should go. The author offers his own vision, one that includes (1) establishing true partnerships between medical schools and the communities they serve; (2) elevating prevention and health maintenance to equal status with diagnosis and treatment; (3) addressing pressing social problems, such as drug abuse, teenage pregnancy, and domestic violence; (4) assuming a leadership role in containing health care costs; (5) harnessing information technology to develop, disseminate, and implement comprehensive clinical information systems, and to provide the public with reliable medical information; (6) fostering racial, ethnic, and gender parity in medicine; (7) carrying out appropriate downsizing and restructuring of the academic medicine enterprise; (8) addressing forcefully the workforce needs for physicians and medical scientists; (9) improving the education of medical students and residents and fostering the conduct of clinical research by creative use of the integrated academic health care systems that teaching hospitals are becoming; (10) developing regional educational consortia to guide important aspects of medical students' and residents' education; (11) building a learning network so that meaningful cross-talk and dissemination of lessons learned can occur among all segments of the academic medicine community; and (12) creating a permanent planning process to guide academic medicine's future. The author concludes that if academic medicine adheres to its tradition of public service and professionalism, its future can be as glorious as its past.

Academic Medical Centers↗
PubMed2004

The locus of perceived equidistance in binocular vision.

Empirical studies of the locus of perceived equidistance in binocular vision have revealed a characteristic change of its form, depending on absolute distance. This result is commonly taken to indicate influence of vergence-related binocular information, a conclusion that is by no means exclusively dictated by the data. Heller (1997) has suggested an alternative theoretical account that is based on the idea of independently combining the outcome of monocular input transformations without any form of binocular interaction. This article provides an experimental test of the structural assumption lying at the core of the axiomatic foundation of Heller's theory. I test the so-called Reidemeister condition under reduced cue conditions in two settings for each of 7 subjects. The results provide strong evidence for the validity of the Reidemeister condition and thus challenge the view that the locus of perceived equidistance depends on vergence-related binocular information. The discussion of the factors contributing to the monocular input transformations emphasizes the role of the optical properties of the eyes.

Adult↗
PubMed2001

Evaluation of the NEI visual functioning questionnaire as an interval measure of visual ability in low vision.

The National Eye Institute developed a visual functioning questionnaire (NEI-VFQ) designed to assess health-related quality of life of patients with visual impairments. The developers of the NEI-VFQ distributed the original 52 items into 13 different domains. The recommended method for scoring the NEI-VFQ is to linearly transform the sum of the ordinal ratings to each item within each domain to produce 13 scores. The major shortcoming of this scoring method is that sums of ordinal numbers do not necessarily generate valid measurement scales. However, Rasch models can be used to estimate interval measurement scales from ordinal responses to items. We administered 27 items from the 52-item NEI-VFQ to 341 patients with low vision. Rasch analysis was used to estimate the 'visual ability' required by each item for a particular response (item measures) and to estimate the 'visual ability' of each patient (person measures). The validity of the model was evaluated by examining the distributions of residuals for item and person measures. We observed that the 17 items we tested from the NEI-VFQ that require difficulty ratings produce a valid interval scale for low-vision patients. The estimated person measures of visual ability are linear with log MAR acuity. The ten items that require frequency or level of agreement ratings do not work together to produce a valid interval scale. Rather, these items appear to be confounded by other variables distributed in the patient sample (e.g. psychological state). The visual ability scale estimated from the 17 NEI-VFQ items is proportional to the visual ability scales estimated from two earlier studies that also elicited difficulty ratings from low-vision patients.

Adolescent↗
PubMed2002

The role of methodologies to improve efficiency and effectiveness of care delivery processes for the year 2013.

This paper aims at further expanding the vision of future health care delivery systems presented by Haux et al. (2002). Starting from the observation that information and communication technology (ICT) is deeply transforming the shape of organizations as expected, we argue that the coordination of work activities is a fundamental need for any organization. This is even more important for health care organizations since there is an increasing pressure to increase quality of care they deliver without further increasing its costs. However ICT by itself will not cause the desired changes without rethining the way of managing best practice biomedical knowledge and care delivery processes. Thus the paper focuses on the need of developing intense research efforts in the fields of knowledge management and workflow modelling, which have been identified as fundamental to provide suitable solutions to the problems of designing and building innovative health care information systems. Moreover, the paper discusses the role of mobile communication systems. Moreover, the paper discusses the role of mobile communication and speech understanding technologies to support a satisfactory user-system interaction in daily work.

Biomedical Research↗
PubMed2002

A novel telemedicine method for viewing the open surgical field.

BACKGROUND AND PURPOSE: The surgical theater has undergone a series of transformations from an open stadium-like environment to the closed environment of minimally invasive endoscopic surgery. Paradoxically, evolution from open surgery performed under direct vision to closed surgery performed through use of video images has been accompanied by improved viewing of the operative field by student observers. The objective of these experiments was to determine if a laparoscope mounted on the operating table during open surgery would provide students a better view of the operative field than that provided while standing behind the operating surgeon or via an optimally positioned hand-held video camera. MATERIALS AND METHODS: An endoscopic video camera and telescope were attached to an operating table by an Alpha Virtual Port, which facilitates use of the laparoscope in open surgery by fixing it to the operating table in the position of interest. Additional imaging systems were set up so as to simulate viewing of the surgical field by direct vision or a hand-held video camera. Common objects were placed on the operating table in mock surgical fields of various depth-to-aperture ratios. Images of these surgical fields were obtained by each of these systems and placed in a Web-based tool. Eleven people with a wide range of medical training evaluated the images and determined that the Alpha Port-mounted surgical telescope provided optimal visibility of the mock open surgical field. RESULTS AND CONCLUSION: The benefit of use of the mounted telescope was more pronounced as the depth-to-aperture ratio of the surgical field increased. Use of the Alpha Port-mounted laparoscope in open surgical procedures improves student viewing of the open surgical field.

Laparoscopes↗
PubMed2001

Molecular Dissection of the 5' Region of no-on-transientA of Drosophila melanogaster Reveals cis-Regulation by Adjacent dGpi1 Sequences.

The nonA gene of Drosophila melanogaster is important for normal vision, courtship song, and viability and lies approximately 350 bp downstream of the dGpi1 gene. Full rescue of nonA mutant phenotypes can be achieved by transformation with a genomic clone that carries approximately 2 kb of 5' regulatory material and that encodes most of the coding sequence of dGpi1. We have analyzed this 5' region by making a series of deleted fragments, fusing them to yeast GAL4 sequences, and driving UAS-nonA expression in a mutant nonA background. Regions that both silence and enhance developmental tissue-specific expression of nonA and that are necessary for generating optomotor visual responses are identified. Some of these overlap the dGpi1 sequences, revealing cis-regulation by neighboring gene sequences. The largest 5' fragment was unable to rescue the normal electroretinogram (ERG) consistently, and no rescue at all was observed for the courtship song phenotype. We suggest that sequences within the nonA introns that were missing in the UAS-nonA cDNA may carry enhancer elements for these two phenotypes. Finally, we speculate on the striking observation that some of the cis-regulatory regions of nonA appear to be embedded within the coding regions of dGpi1.

Alleles↗
PubMedDate not supplied

"Spiritlinking": a key to dynamic change. Fostering chaos enables leaders to form the networks and unity needed to fulfill their mission.

To contend with the anxiety and chaos inherent in rapid change, leaders can turn to ¿spiritlinking,¿ the deliberate and untiring act of building the high-energy networks where new ideas are born and new ways of delivering service take form. Spiritlinking leaders are able to envision and promote the paradox of disequilibrium. They seek truth, pushing the organization into a condition of imbalance where staid settledness gives way to new paradigms founded on constant transformation. Spiritlinking leaders are not bound by organizational charts. They have discovered that the greater the participation in the organization, the greater the access to vast amounts of information and insight, which will ultimately lead to profound transformation. Spiritlinking is directed toward networking, community forming, and coalition building, often across chasms of ideological differences. Leaders must have the skill to manage the vision, which entails generating courage and belief through the cloudiness of ambiguity. Spiritlinking leaders must also create synergy from conflict, gathering strong-minded, self-assured persons who perhaps hold vastly differing perspectives, yet, in working for the common good, arrive at surprising, wonderful decisions. Finally, spiritlinking leaders assist the organization in working through resistance by identifying the mode, motive, and meaning of the resistant behavior and determining the action the organization is willing to take to move beyond it.

Canada↗
PubMed1994

The importance of symmetry and virtual views in three-dimensional object recognition.

BACKGROUND: Human observers can recognize three-dimensional objects seen in novel orientations, even when they have previously seen only a relatively small number of different views of the object. How our visual system does this is a key problem in vision research. Recent theories and experiments suggest that the human visual system might store a relatively small number of sample two-dimensional views of a three-dimensional object, and recognize novel views by a process of interpolation between the stored sample views. These sample views may be collected during a training phase as the visual system familiarizes itself with the object. RESULTS: Here, we investigate whether constraints on the shapes of objects commonly encountered in the real world can reduce the number of training views required for recognition of three-dimensional objects. We are particularly concerned with the constraint of object symmetry. We show that if an object is bilaterally symmetrical, then additional 'virtual views' can automatically be generated from one sample view by symmetry transformations. These virtual views should make it more easy to recognize novel views of a symmetric than an asymmetric object, when a single sample view has been seen. Recognition should be particularly facilitated when the novel views are close to the virtual view. We present psychophysical results that bear out these predictions. CONCLUSIONS: Our results show that the human visual system can indeed exploit symmetry to facilitate object recognition, and support the model for object recognition in which a small number of two-dimensional views are remembered and combined to recognize novel views of the same object. These results raise questions about how symmetry is recognized, and symmetry transformations implemented, in real, biological neural networks.

Depth Perception↗
PubMed2001

Phycomyces and the biology of light and color.

Phycomyces has been in the laboratories for about 140 years, sometimes following trends and fashions, but often anticipating them. Researchers have been attracted by the sensitive and precise responses of Phycomyces to light and other stimuli, coupled with easy manipulations and good adaptation to laboratory life. It is a simple prototype of the many organisms that use light as a source of information but not as a significant source of energy. Growth, development, genetics, and carotene production have been other subjects of pioneering research. Phycomyces was the second organism, after us, known to require a vitamin. It was one of the first organisms in the research on spontaneous mutants and the second, after Drosophila, in which mutations were induced artificially. It was used to coin the concept and the name of heterokaryosis. Phycomyces heterokaryons offer unique experimental possibilities, for instance in the study of gene function in vivo and the causes of cell death. An overall impression of parsimony and combinatorial gene usage arises from the genetic analysis of the complex functions of this fungus. The main subjects of recent attention have been the various reactions to light, gravitropism, and some aspects of metabolism, particularly the production of carotene. Interest in Phycomyces is slacking because of the repeated failures at transforming it stably with exogenous DNA.

Carotenoids↗
PubMed2004

Postural control in athletes participating in an ironman triathlon.

We studied the degree of dependence on vision of static postural control among ten male adult ironmen and ten healthy subjects (firemen, control group) who took part in regular physical activity, and the perturbations of equilibrium after prolonged exercise in ironmen. Static postural stability was measured during standing on a single-force platform alternating between eyes open and eyes closed. First, body sway was analysed on a force plate in both groups, and the athletes then took part in an ironman triathlon. The measurement was repeated after the race. The sway in both directions was subjected to spectral analysis. The frequency spectrum of the platform oscillations was calculated by fast Fourier transformation in the intervals 0-0.3, 0.3-1 and 1-3 Hz. The sway path in both directions and the total path were significantly lower in the ironmen than in the control group without vision, and the absence of visual control caused a significant increase in sway in both directions in the control group, but not in the ironmen. The frequency analysis revealed a higher level of stability in the medio-lateral direction with closed eyes. The endurance race caused increases in both the total sway path only with closed eyes, and these changes were significant at higher frequency bands. These results indicate that ironmen are more stable and less dependent on vision for postural control than the control subjects, and the prolonged stimulation of the proprioceptive, vestibular and visual inputs in the endurance race causes a significant disturbance in postural control.

Adult↗
PubMed2006

The role of memory in guiding attention during natural vision.

What is the time frame in which perceptual memory guides attention? Current estimates range from a few hundred milliseconds to several seconds, minutes, or even days. Here, we answer this question by establishing the time course of attentional selection in realistic viewing conditions. First, we transformed continuous video clips into MTV-style video clips by stringing together continuous clip segments using abrupt transitions (jump cuts). We then asked participants to visually explore either continuous or MTV-style clips and recorded their saccades as objective behavioral indicators of attentional selections. The utilization of perceptual memory was estimated across viewing conditions and over time by quantifying the agreement between human attentional selections and predictions made by a neurally grounded computational model. In the critical condition, jump cuts led to sharp declines in the impact of perceptual memory on attentional selection, followed by monotonic increases in memory utilization across seven consecutive saccades and 2.5 s. These results demonstrate that perceptual memory traces play an important role in guiding attention across several saccades during natural vision. We propose novel hypotheses and experiments using hybrid natural-artificial stimuli to further elucidate neurocomputational mechanisms of attentional selection.

Adult↗
PubMed1995

Beyond the computer-based patient record: re-engineering with a vision.

In order to achieve real benefit from the potential offered by a Computer-Based Patient Record, the capabilities of the technology must be applied along with true re-engineering of healthcare delivery processes. University Hospital recognizes this and is using systems implementation projects, such as the catalyst, for transforming the way we care for our patients. Integration is fundamental to the success of these initiatives and this must be explicitly planned against an organized systems architecture whose standards are market-driven. University Hospital also recognizes that Community Health Information Networks will offer improved quality of patient care at a reduced overall cost to the system. All of these implementation factors are considered up front as the hospital makes its initial decisions on to how to computerize its patient records. This improves our chances for success and will provide a consistent vision to guide the hospital's development of new and better patient care.

Computer Communication Networks↗
PubMed1998

Mechanisms of central color vision.

In monkey cerebral cortex, color information is processed along the ventral visual pathway. This pathway starts in the primary visual cortex and ends in area TE of the inferior temporal cortex. Recent studies indicate that the transformation of cone signals occurs early in the pathway to form neurons selective to a narrow range of hues. In addition, it has become apparent that area TE plays a vital role in color discrimination.

Animals↗
PubMed1981

Fibrous ingrowth with retrocorneal membrane.

A case of retrocorneal fibrous membrane is reported in a patient who underwent cataract extraction and experienced a postoperative hyphema. A distinctive straw-colored appearance to the membrane was due to blood staining. A penetrating keratoplasty with extensive anterior segment surgery restored the eye to useful vision. The penetrating keratoplasty specimen disclosed an unusual double-layered retrocorneal fibrous membrane, produced in part by a vascularized fibrous ingrowth and also by fibroblastic transformation of the corneal endothelial cells.

Anterior Chamber↗