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Measurements of human sensitivity to comb-filtered spectra.

Using a novel stimulator that incorporates a liquid crystal display, the spectral modulation sensitivity function of the colour vision system was derived by measuring discrimination thresholds for comb-filtered spectra. This function shows a peak of sensitivity at 0.97 c/300 nm with a plateau that extends to 1.67 c/300 nm. Extrapolation of the curve gives an estimated high-frequency cut-off at 5 c/300 nm. The thresholds are also transformed to the CIE (1931) diagram and the elliptical isosensitivity contours thus obtained are compared with the classical discrimination ellipse of MacAdam for the corresponding region of colour space.

Color Perception↗

Malignant rhabdoid tumor in a pregnant adult female: literature review of central nervous system rhabdoid tumors.

Rhabdoid tumors of the central nervous system are uncommon, aggressive childhood malignancies. The 13 described adult cases comprise both primary CNS tumors and malignant transformation of previously existing gliomas, meningiomas, and astrocytomas. Central nervous system rhabdoid lesions of adults have been diagnosed as primary malignant rhabdoid tumors, atypical teratoid/rhabdoid tumors, and more recently, rhabdoid glioblastomas. We report a case of a 20-year-old woman in her 30th week of pregnancy who presented with headache, nausea and blurry vision. MRI revealed a large rim-enhancing mass of the right occipital lobe. Gross total resection was achieved via a right parietal-occipital craniotomy. Pathologic evaluation revealed histology, electron microscopy and immunohistochemistry consistent with the diagnosis of malignant rhabdoid tumor. FISH studies were negative for the INI-1 genetic mutations and chromosome 22q deletion associated with childhood atypical rhabdoid/rhabdoid tumor in 75% of cases. The patient delivered her infant via caesarian section prior to initiating further therapy. We briefly describe the characteristics and current understanding of rhabdoid tumors, and review the literature comparing the 12 other cases of central nervous system rhabdoid tumors in adults. Furthermore, we consider and discuss the implications of this case being the second presentation of MRT during pregnancy in only six adult female patients.

Adult↗

Dynamical systems and cognitive linguistics: toward an active morphodynamical semantics.

We propose a novel dynamical system approach to cognitive linguistics based on cellular automata and spiking neural networks. How can the same relationship 'in' apply to containers as different as 'box', 'tree' or 'bowl'? Our objective is to categorize the infinite diversity of schematic visual scenes into a small set of grammatical elements and elucidate the topology of language. Gestalt-inspired semantic studies have shown that spatial prepositions such as 'in' or 'above' are neutral toward the shape and size of objects. We suggest that this invariance can be explained by introducing morphodynamical transforms, which erase image details and create virtual structures or singularities (boundaries, skeleton), and call this paradigm 'active semantics'. Singularities arise from a large-scale lattice of coupled excitable units exhibiting spatiotemporal pattern formation, in particular traveling waves. This work addresses the crucial cognitive mechanisms of spatial schematization and categorization at the interface between vision and language and anchors them to expansion processes such as activity diffusion or wave propagation.

Algorithms↗

Professional practice leader: a transformational role that addresses human diversity.

The role of the professional practice leader is to provide leadership in the transformation of nursing practice from a provider focused model to a patient focused model. Nursing standards for patient focused care were developed to define the quality of the nurse-person relationship in a manner consistent with Parse's theory of human becoming. Multiple strategies have been developed to challenge nurses to redefine the purpose, vision, and core values by which they practice. It is only through uncovering the values and beliefs of every person that nurses will be able to care for individuals whom they recognize as unique human beings.

Cultural Diversity↗

Driving the quality transformation: what's missing?

Around the country, healthcare providers are using the tools of continuous improvement to redesign patient care, match customer needs with available resources, and make management decisions based on data-driven analyses of key processes. Initiatives such as these are producing positive changes within healthcare organizations, but two serious barriers all but preclude improvement at the system level: a compensation process that punishes innovation and the emergence of integrated care systems that lack a common vision. Unless these barriers can be removed, insists the author, healthcare providers ultimately will be unsuccessful in their effort to improve value for their customers.

Consumer Behavior↗

Modulation sensitivity and functional organization of the receptive field of ganglion cells in the pigeon (Columba livia).

Modulation sensitivity functions ( MSFs ) of retinal ganglion cells of the pigeon were determined by recording action potentials from their end branching in the optic tectum as response indicator. The inverse Fourier transformation of a MSF is taken to represent the receptive field sensitivity function approximating the receptive field profile of a ganglion cell.

Action Potentials↗

Perception of apparent motion between dissimilar gratings: spatiotemporal properties.

What determines the strength of texture-defined apparent motion perception when the stimulus has no net directional energy in the Fourier domain? In a previous paper [Werkhoven, Sperling & Chubb (1993) Vision Research, 33, 463-485] we demonstrated the counterintuitive finding that the correspondence in spatial frequency and in modulation amplitude between neighboring patches of texture in a spatiotemporal motion path are irrelevant to motion strength. Instead, we found strong support for what we call a single channel or one-dimensional motion computation: a simple nonlinear transformation of the image, followed by standard motion analysis. Here, we further studied the dimensionality of the motion computation in a parameter space that includes texture orientation and stimulus display rate in addition to texture spatial frequency and modulation amplitude. We used ambiguous motion displays in which one motion path, consisting of patches of nonsimilar texture, competes with another motion path comprised entirely of similar texture patches. The data show that motion between dissimilar patches of texture that are orthogonally oriented, have a two octave difference in spatial frequency and differ 50% in modulation amplitude can easily dominate motion between similar patches of texture. A single channel accounts for more than 70% of texture-from-motion strength for the parameter space examined and this channel is invariant for stimulus display rates varying over a four-fold range.

Humans↗

Star scientists and institutional transformation: patterns of invention and innovation in the formation of the biotechnology industry.

The most productive ("star") bioscientists had intellectual human capital of extraordinary scientific and pecuniary value for some 10-15 years after Cohen and Boyer's 1973 founding discovery for biotechnology [Cohen, S., Chang, A., Boyer, H. & Helling, R. (1973) Proc. Natl. Acad. Sci. USA 70, 3240-3244]. This extraordinary value was due to the union of still scarce knowledge of the new research techniques and genius and vision to apply them in novel, valuable ways. As in other sciences, star bioscientists were very protective of their techniques, ideas, and discoveries in the early years of the revolution, tending to collaborate more within their own institution, which slowed diffusion to other scientists. Close, bench-level working ties between stars and firm scientists were needed to accomplish commercialization of the breakthroughs. Where and when star scientists were actively producing publications is a key predictor of where and when commercial firms began to use biotechnology. The extent of collaboration by a firm's scientists with stars is a powerful predictor of its success: for an average firm, 5 articles coauthored by an academic star and the firm's scientists result in about 5 more products in development, 3.5 more products on the market, and 860 more employees. Articles by stars collaborating with or employed by firms have significantly higher rates of citation than other articles by the same or other stars. The U.S. scientific and economic infrastructure has been particularly effective in fostering and commercializing the bioscientific revolution. These results let us see the process by which scientific breakthroughs become economic growth and consider implications for policy.

Academies and Institutes↗

[Long-term follow-up study of nonischemic central retinal vein occlusion].

OBJECTIVE: To explore the clinical characteristic, visual prognosis and related factors of nonischemic central vein occlusion. METHODS: Retrospective data analysis (including visual acuity, color fundus photography and fundus fluorescein angiography) was conducted in patients with nonischemic CRVO who were followed-up for 3 years or longer. RESULTS: The data of 35 cases (37 eyes) were analyzed. The follow-up time was 3 - 15 years, averaged 4.5 years. Age of those patients ranged from 18 to 76 years, averaged 56 years. Thirty cases (32 eyes) were over 40 years old. Two cases had chronic angle closure glaucoma. At the final visit, visual acuity improved in only 2 eyes (5%), remained the same in 11 eyes (30%), and decreased in 24 eyes (65%). Twenty-eight eyes (75%) had a final visual acuity of 20/200 or less. Nine eyes (24%) transformed to the ischemic type, among which neovascular glaucoma occurred in 5 eyes. Macular complications were the major causes of serious visual impairment. The patients with chronic angle closure glaucoma and partial optic nerve atrophy had relatively good final visual acuity. CONCLUSIONS: Nonischemic CRVO can cause severe visual impairment. Macular complications are the major causes of vision loss. Partial optic nerve atrophy may have a protective effect on visual acuity in CRVO.

Adolescent↗

How neural interactions form neural responses in the salamander retina.

A wide range of experimental data characterizing properties of individual salamander retinal cells and synaptic interactions are integrated to form a quantitative computational model of visual function in the salamander retina. The model is used to show how specific interactions between neurons and between networks of neurons can lead-to the integrated response behavior of individual cells deep in the retina. The model is also used to illustrate how the representation of moving and stationary stimuli is encoded in a series of layer-by-layer transformations leading to the final retinal output at the ganglion cell layer.

Animals↗

Tool use and the effect of action on the imagination.

Three studies examined the claim that hand movements can facilitate imagery for object rotations but that this facilitation depends on people's model of the situation. In Experiment 1, physically turning a block without vision reduced mental rotation times compared with imagining the same rotation without bodily movement. In Experiment 2, pulling a string from a spool facilitated participants' mental rotation of an object sitting on the spool. In Experiment 3, depending on participants' model of the spool, the exact same pulling movement facilitated or interfered with the exact same imagery transformation. Results of Experiments 2 and 3 indicate that the geometric characteristics of an action do not specify the trajectory of an imagery transformation. Instead, they point to people's ability to model the tools that mediate between motor activity and its environmental consequences and to transfer tool knowledge to a new situation.

Adult↗

Egg colour matching in an African cuckoo, as revealed by ultraviolet-visible reflectance spectrophotometry.

Despite major differences between human and avian colour vision, previous studies of cuckoo egg mimicry have used human colour vision (or standards based thereon) to assess colour matching. Using ultraviolet-visible reflectance spectrophotometry (300-700 nm), we measured museum collections of eggs of the red-chested cuckoo and its hosts. The first three principal components explained more than 99% of the variance in spectra, and measures of cuckoo host egg similarity derived from these transformations were compared with measures of cuckoo host egg similarity estimated by human observers unaware of the hypotheses we were testing. Monte Carlo methods were used to simulate laying of cuckoo eggs at random in nests. Results showed that host and cuckoo eggs were very highly matched for an ultraviolet versus greenness component, which was not detected by humans. Furthermore, whereas cuckoo and host were dissimilar in achromatic brightness, humans did not detect this difference. Our study thus reveals aspects of cuckoo-host egg colour matching which have hitherto not been described. These results suggest subtleties and complexities in the evolution of host-cuckoo egg mimicry that were not previously suspected. Our results also have the potential to explain the longstanding paradox that some host species accept cuckoo eggs that are non-mimetic to the human eye.

Animals↗

A survey in action. The "next wave assessment" takes shape.

With the initiation of the Health Care 2000 vision project in 1988, the MHA established itself as one of the first state hospital associations to strategically assess important health care trends and craft a framework for the future of health care delivery and financing for its membership. The 1990s have brought much change and unprecedented challenge to the health care field. As MHA continues to transform to meet the needs of its members, the time has come to reassess our health care environment and critically examine our assumptions about the future.

Delivery of Health Care↗

Spectral tuning of rhodopsin and metarhodopsin in vivo.

Color vision is dependent upon the expression of spectrally distinct forms of rhodopsin in different photoreceptor cells. To identify the structural features of rhodopsin that regulate spectral sensitivity and absorption in vivo, we have constructed a series of chimeric Drosophila rhodopsin molecules, derived from a blue- and a violet-sensitive rhodopsin, and used P element-mediated germline transformation to generate transgenic flies that express the modified pigments in the R1-R6 photoreceptor cells of the compound eye. Our analysis of these animals indicates that multiple regions of the opsin protein are involved in regulating rhodopsin spectral sensitivity and that the native and photoactivated forms of rhodopsin can be tuned independently of each other. These results demonstrate the feasibility of designing receptor molecules with specifically modified activated states.

Amino Acid Sequence↗

Visualization of inner ear structures by three-dimensional high-resolution magnetic resonance imaging.

High-resolution computed tomography (CT) has long been the method of choice in the visualization of the petrous bone, the internal auditory canal, and the cerebellopontine angle. The introduction of magnetic resonance imaging (MRI), especially of the three-dimensional Fourier transformation constructive interference in steady state (3DFT-CISS), has proved to be superior in the detection of soft-tissue lesions in the inner ear. The aim of this study was to visualize small anatomic structures of the inner ear and cerebellopontine angle. The examinations were performed with a standard head coil on a 1.5-T Magnetom ("Vision"; Siemens, Erlangen, Germany). The three-dimensional reconstruction of the cochlea, semicircular canals, and vestibulum allowed detailed visualization, as well as the imaging of cranial nerves VII and VIII. Our results indicate that 3DFT-CISS MRI is a valuable diagnostic tool in the evaluation of inner ear anatomy and pathology; in most cases, however, it must be supplemented by HR-CT.

Aged↗

The future of the IAIMS in a managed care environment: a call for private action and public investment.

A national public and private "grand challenge" initiative should be undertaken to assure the American public that the telecommunications and computing revolutions improve health care, health education, and biomedical and health services research, and secure accountability for cost, quality, and access. The initiative should focus on meeting the needs of the patient and society at large. It needs to be a national vision, but it also ought to have regional focus. A plan for action would include a health-infrastructure strategy, a service strategy, an education strategy, a research and development strategy, and an international-linkages strategy. Without this type of initiative, health care will lack the basic building blocks it needs to more effectively deal with the transformational forces that have already been unleashed. These forces will strengthen or weaken health care in the next century depending on whether and how the nation--including the leadership in health care and the informatics community--responds to this challenge.

Academic Medical Centers↗

Contrast sensitivity functions to stimuli defined in Cartesian, polar and hyperbolic coordinates.

Recent electrophysiological studies indicate that cells in the LGN, V1, V2, and V4 areas in monkeys are specifically sensitive to Cartesian, polar and hyperbolic stimuli. We have characterized the contrast sensitivity functions (CSF) to stimuli defined in these coordinates with the two-alternatives forced-choice paradigm. CSFs to Cartesian, concentric, and hyperbolic stimuli have had similar shapes, with peak sensitivity at approximately 3 c/deg. However, the Cartesian CSF peak sensitivity has been at least 0.1 log units higher than that to stimuli in any other coordinate system. The concentric-Bessel CSF has a low-pass shape, peaking at 1.5 c/deg or below. The radial CSF has a bell shape with maximum sensitivity at 8 c/360 degrees. Only the concentric-Bessel CSF could be explained in terms of the components of maximum amplitude of the Fourier transform. Neural models, which in previous studies predicted the responses to Cartesian and polar Glass patterns, failed to account for the full CSFs data.

Contrast Sensitivity↗

Weakening the robustness of perspective: evidence for a modified theory of compensation in picture perception.

Viewed from the center of projection, a perspective picture presents the pictorial depth information of a scene. Knowing the center of projection, one can reconstruct the depicted scene. Assuming another viewpoint is the center of projection will cause one to reconstruct a transformed scene. Despite these transformations, we appreciate pictures from other viewpoints. The compensation hypothesis states that the visible picture surface allows observers to compensate for transformations by locating the center of projection and experiencing pictorial space from there. We show that observers neither completely compensate for nor experience transformations of space as geometry would predict. We propose a modified compensation hypothesis according to which different degrees of visibility of the picture surface invoke different degrees of compensation.

Female↗