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PubMed2005

Visual correlates of fixation selection: effects of scale and time.

What distinguishes the locations that we fixate from those that we do not? To answer this question we recorded eye movements while observers viewed natural scenes, and recorded image characteristics centred at the locations that observers fixated. To investigate potential differences in the visual characteristics of fixated versus non-fixated locations, these images were transformed to make intensity, contrast, colour, and edge content explicit. Signal detection and information theoretic techniques were then used to compare fixated regions to those that were not. The presence of contrast and edge information was more strongly discriminatory than luminance or chromaticity. Fixated locations tended to be more distinctive in the high spatial frequencies. Extremes of low frequency luminance information were avoided. With prolonged viewing, consistency in fixation locations between observers decreased. In contrast to [Parkhurst, D. J., Law, K., & Niebur, E. (2002). Modeling the role of salience in the allocation of overt visual attention. Vision Research, 42 (1), 107-123] we found no change in the involvement of image features over time. We attribute this difference in our results to a systematic bias in their metric. We propose that saccade target selection involves an unchanging intermediate level representation of the scene but that the high-level interpretation of this representation changes over time.

Attention↗
PubMed1986

Electrophysiological assessment of contrast sensitivity in human infants.

Contrast sensitivity functions (CSF's) were measured for a group of 6-month-old infants using the visual evoked potential (VEP). Sine-wave luminance gratings were counterphase modulated at 12 contrast reversals per s and simultaneously swept in contrast. Each contrast sweep lasted 10 s, spanning a range of 0.5 to 40% contrast in 19 equal logarithmic steps. The amplitude and phase of the response at the second harmonic were determined by a discrete Fourier transform. Contrast thresholds were estimated from a linear extrapolation to zero-amplitude of the VEP amplitude vs. log-contrast function. Contrast sensitivity was found to be nearly adult-like at 1 c/deg, but was not yet mature at higher spatial frequencies.

Child Development↗
PubMed1992

Stable isotope tracer analysis by GC-MS, including quantification of isotopomer effects.

In metabolic tracer studies it is frequently useful to infuse tracers that are differently labeled variants of the same molecule. These tracers are known as isotopomers. Analysis of the enrichment of each isotopic analogue can be accomplished by gas chromatography-mass spectrometry (GC-MS). However, the raw GC-MS data must be corrected to give the information required. This paper addresses how to transform the raw GC-MS data, consisting of relative abundance ratios at specific ion masses, into relative molar ratios of tracer and tracee molecules. Several correction factors are necessary. First, the background must be measured and corrected for, since it is always present in the sample. Second, the abundances in the spectrum of the labeled molecule are different from those in the unlabeled molecule, and this proportionality "skew" is corrected. A third correction factor accounts for the overlapping spectra of two or more isotopomers that cannot be measured independently. The final correction removes the "double vision" effect that may appear in some spectra due to the presence of (M - H)+ species.

Drug Stability↗
PubMedDate not supplied

Death-related sensory experiences.

A death-related sensory experience (DRSE) is a spiritually transforming experience occurring with the appearance of a messenger beyond the visible observable universe to guide a dying person through the dying process. DRSEs have been reported to occur among those who are dying, most commonly individuals with terminal illness. Known dead family members are most commonly seen, followed by religious beings. Communication takes place between the dying individual and the apparition. Feelings of peace and comfort are reported by the majority of individuals experiencing DRSEs. DRSEs can occur over a period of hours to months before death. They have been referred to as veridical hallucinations, visions of the dying, deathbed visions, and predeath visions. Reported throughout time, among people of all cultures, religions, races, ages, genders, socioeconomic status, and educational levels, DRSEs are intense spiritual experiences. Validating a child's DRSE provides a way to start a dialogue regarding death. Research is needed to more fully understand DRSEs from the perspective of the dying child.

Adolescent↗
PubMed2002

Development of a new extended-wear contact lens model in the rat.

PURPOSE: To develop a rat model to experimentally monitor the potential inflammatory effects of soft contact lens (CL) usage on the cornea during extended wear (EW). METHODS: Lewis rats were fitted with EW lotrafilcon A (CIBA Vision, Duluth, GA) hydrogel lenses (Dk/t 175 barrers/cm) in the left eye, the right eye serving as a control. After 12 days (n = 5 rats) and 30 days (n = 8 rats) of continuous extended wear, corneas were removed and total RNA was extracted from both CL-wearing and non-lens-wearing eyes. Multiprobe ribonuclease protection assays (RPA) were used to detect and compare cytokine and chemokine gene expression in corneas from both groups. RESULTS: Cytokine-chemokine mRNA expression levels were similar for interleukin (IL)-1alpha, IL-1 receptor antagonist (RA), IL- 18, transforming growth factor (TGF)-beta1, TGF-beta2, TGF-beta3, and macrophage migration inhibitory factor (MIF) levels in CL-wearing and non-lens-wearing corneas after 12 or 30 days of EW. CONCLUSION: This in vivo rat model for extended contact lens wear allows analysis and comparison of mRNA levels of cytokines and chemokines in the cornea with and without EW soft CL use. Remarkably, after 12 or 30 days of continuous CL wear, there was no significant up-regulation in lens wearing corneas for any of the cytokines-chemokines tested.

Animals↗
PubMed2000

[Off-site and alternative services in community mental health care in Quebec].

The objective of this article is to understand the evolution of the practice of "elsewhere" and "otherwise" that alternative community resources in Québec have consistently advocated. Towards this end, we begin by identifying the meaning and significance of the ideas of "elsewhere" and "otherwise" in the context of the transformation of Quebec's mental health system since 1989. Then we present the results of an exploratory study carried out between 1997 and 1999 in which the coordinators as well as members of 6 community mental health organisations in a semi-urban region of Quebec were interviewed. The results of the study suggest the validity of certain fears that community resources are becoming "deradicalized." The analysis presented here suggests the unfolding of a complex process involving the integration of alternative resources into the broader public mental health system, internal dynamics, and the emerging limitations of the vision of "elsewhere" and "otherwise" that has guided them until now. Twenty years after alternative community resources appeared on the Quebec mental health scene, is it time to reform the philosophy of "elsewhere" and "otherwise"?

Community Mental Health Services↗
PubMed2002

Transforming health information management through technology.

No one would deny the need to transform health care. Information technology is capable of transforming health care organizations and delivering measurable value. However, these organizations will have to deploy effective, proactive strategies for managing information and adapting to the opportunities the technology offers. If, for example, an organization wants to become paperless, its information strategy must include appropriate tools to store and access unstructured data components of the medical record as well as structured data. An Electronic Document Management System (EDMS) is a critical element of this strategy. Also, a plan for managing change must be developed to mitigate technology risks. This can be realized through the development of a clear vision of the future and strong leadership, among other key items.

Cost Control↗
PubMed1996

[Melanoma developped on nevus of Ota without ocular melanosis. Apropos of an anatomo-clinical case].

The naevus of Ota is a congenital pigmentary disorder usually involving the skin of the face in areas supplied by the first and second branches of the trigeminal nerve. Ipsilateral ocular melanosis is associated in 2/3 of the cases. The naevus occurrs most often in Asians. There have been 66 reported cases of malignant transformation of the naevus of Ota, generally affecting caucasians: 23 were melanomas of the eyeball (mostly of the choroid), and 13 were orbital melanomas. Only 4 cases of melanomas associated with a naevus of Ota without ocular melanosis have been previously described. We report a new case of orbital melanoma affecting a 30-year-old man. This melanoma complicated a right type III of Tanino naevus of Ota without ocular melanosis. The location of the tumor to the orbital apex and its extension to the spheno-cavernous area was responsible for an ipsilateral loss of vision without proptosis, which has not yet been described in any case of naevus of Ota without ocular melanosis.

Adult↗
PubMed2005

A phantom evaluation of a stereo-vision surface imaging system for radiotherapy patient setup.

External beam irradiation requires precise positioning of the target relative to the treatment planning coordinate system. A three-dimensional (3D) surface imaging system for patient positioning has recently been installed in one of our linear accelerator (linac) rooms. The device utilizes close-range photogrammetry to generate a 3D model of the patient's surface. This geometric model can be made to look like a digital camera image if wrapped with a gray-level image (texture mapping) that shows surface coloration. The system is calibrated to the linac coordinate system and has been designed as a patient setup device. To reproduce patient position in fractionated radiotherapy, the daily patient surface model is registered to a previously recorded reference surface. Using surface registration, the system calculates the rigid-body transformation that minimizes the distance between the treatment and the reference surface models in a region-of-interest (ROI). This transformation is expressed as a set of new couch coordinates at which the patient position best matches with the reference data. If respiratory motion is a concern, the surface can be obtained with a gated acquisition at a specified phase of the respiratory cycle. To analyze the accuracy of the system, we performed several experiments with phantoms to assess stability, alignment accuracy, precision of the gating function, and surface topology. The reproducibility of surface measurements was tested for periods up to 57 h. Each recorded frame was registered to the reference surface to calculate the required couch adjustment. The system stability over this time period was better than 0.5 mm. To measure the accuracy of the system to detect and quantify patient shift relative to a reference image, we compared the shift detected by the surface imaging system with known couch transitions in a phantom study. The maximum standard deviation was 0.75 mm for the three translational degrees of freedom, and less than 0.1 degrees for each rotation. Surface model precision was tested against computed tomography (CT)-derived surface topology. The root-mean-square rms of the distance between the surfaces was 0.65 mm, excluding regions where beam hardening caused artifacts in the CT data. Measurements were made to test the gated acquisition mode. The time-dependent amplitude was measured with the surface imaging system and an established respiratory gating system based on infrared (IR)-marker detection. The measured motion trajectories from both systems were compared to the known trajectory of the stage. The standard deviations of the amplitude differences to the motor trajectory were 0.04 and 0.15 mm for the IR-marker system and the 3D surface imaging system, respectively. A limitation of the surface-imaging device is the frame rate of 6.5 Hz, because rapid changes of the motion trajectory cannot be detected. In conclusion, the system is accurate and sufficiently stable to be used in the clinic. The errors computed when comparing the surface model with CT geometry were submillimeter, and deviations in the alignment and gating-signal tests were of the same magnitude.

Humans↗
PubMedDate not supplied

Well differentiated "lipoma-like" liposarcoma of the sigmoid mesocolon and multiple lipomatosis of the rectosigmoid colon. Report of a case.

Liposarcoma is the second most common soft tissue sarcoma in adults. These neoplasms take their origin from primitive mesenchymal cells and are rarely encountered in fat rich areas, such as subcutaneous tissue and/or the subserosa of the intestinal tract which, on the contrary, are the two most common sites of lipomas. The two major locations of liposarcomas are the extremities and the retroperitoneum followed with much less frequency by the inguinal region. Other sites are uncommon, particularly the mesentery (9 cases to date in the literature) and, even more so, the mesocolon (only 3 cases of primary sarcoma of the mesocolon reported to date). This paper reports on the case of a well differentiated "lipoma-like" liposarcoma of the sigmoid mesocolon, associated with multiple lipomatosis of the recto-sigmoid colon in a 75 year-old female patient. Surgical treatment consisted of a trans-anal extra-peritoneal anterior resection by CEEA 28 stapler under endoscopic vision. The patient has been followed up for the last 2 years and is still disease-free and well. The peculiarity of the case consists in the contemporaneous presence in close contiguity of two different rare neoplasms whose association is not yet known.

Adult↗
PubMed1982

Medicalized killing in Auschwitz.

Since late 1977 I have been conducting a psychological study of medical behavior in Auschwitz, and of Nazi doctors in general. I have been especially interested in the relationship of doctors, SS doctors in particular, to the killing process--in the transformation from healer to killer. I am concerned with the importance of the medicalized pattern for the overall Nazi project of mass murder and have therefore tried to examine the interaction of biomedical ideology, political ideology, and individual behavior. Finally, the work raises questions of more general significance: for doctors and medicine elsewhere; for scientists, other professionals, and institutions of all kinds; for approaches to "triage" and control over life and death; and for our understanding of human nature and human values. After describing how I did the study, I will discuss what I call the Nazi "biomedical vision" and its relationship to the killing of mental patients as well as to Auschwitz. Next I will suggest features of the Auschwitz atmosphere, particularly in regard to the psychological factors, or mechanisms, that enabled the Nazi doctors to do what they did. Finally, I will turn very briefly to the more general problems raised by the study.

Attitude of Health Personnel↗
PubMed1992

The self you seek is the self you find: recent works on the empty, satiated, and/or transformed self.

In the past two decades, theorists from a variety of disciplines have written and spoken volumes about what they call "the self." Psychoanalytic theorists, drawing on British object relations, American ego psychology, and Kohut's self psychology have elaborated various sets of schemas of the development of both the healthy and the pathological self and its relations to others; postmodern theorists, drawing on Lacan and Derrida, have elaborated quite different schemas. Feminist theorists, using the lens of gender to focus on the self, have discovered still other possible schemas, even as they acknowledge a debt either to the postmodern or to the object relations tradition. The authors under review here all take as their topic current problems in selfhood and how they affect our relations to others. Most have discovered that contemporary psychoanalytic theory illuminates in new ways our vision of other fields of human activity, such as our relation to the sacred and our relation to literary texts.

Adaptation, Psychological↗
PubMed2006

Texture segregation on the basis of contrast polarity of odd-symmetric filters.

This is the first study to demonstrate the selectivity of learning for contrast polarity. The finding is the main result of an investigation into the existence of central and peripheral vision mechanisms selective for contrast polarity within the texture-segregation process, using the perceptual learning paradigm in a detection task. Energy models (Malik & Perona, 1990) exclude segregation of textures composed of elements of odd-symmetric luminance profile by contrast polarity differences. Here the target was a Gabor patch (0.8 deg) of 1 cyc/deg in sine phase (odd-symmetry) embedded in a background of mirror-image elements. Our results showed that, in fovea, segregation on the basis of contrast polarity was above threshold from the first session. After learning, the target popped-out in both central and peripheral vision for durations over 10 ms. Our major result is that learning is selective for contrast polarity; it is also selective for orientation and position, all characteristics distinctive of early processing. Since the learning effects were obtained with texture composed of odd-symmetric mirror-image elements, they indicate that the output from odd-symmetric filters was not excluded or inhibited in texture segmentation, but instead played an active role. Our data support models of texture segmentation, in which detection of texture gradient is achieved on the basis of early cortical process, before the non-linear transformation of their output.

Adult↗
PubMed1981

Critical periods for the transmission of tactual information.

There is good evidence for critical periods in the development of sensory processes (particularly vision and hearing) and language functions. If appropriate experience is absent during these critical periods, later performance is impaired. This principle is of importance to designers of devices which use the skin as an alternative channel of communication for the blind of the deaf. The implications are that: (a) Some promising devices may have been prematurely abandoned because they were tested on adults rather than children. (b) Tactile devices should be evaluated in studies with children who have not yet passed through the critical period for touch and language development. It is argued that early exposure to a tactile transformation of speech (for example) might provide the profoundly deaf with two significant advantages. Firstly, early exposure increases the chance that the cutaneous system will develop neural connections appropriate to the handling of the transformed speech signal. In other words, tactile sensitivity can be optimized. Secondly, early exposure to language as a process associated with the cutaneous system (rather than the auditory system) might favour the development of cortical connections consistent with the sensory substitution system. Such plasticity might no longer exist when the critical period has passed.

Brain↗
PubMed1982

Multiplication noise in the human visual system at threshold: 1. Quantum fluctuations and minimum detectable energy.

We have carried out a series of frequency-of-seeing experiments similar to those performed by Hecht, Shlaer, and Pirenne [J. Gen. Physiol. 25, 819-840 (1942)], using an Ar+ laser operated at 514.5 nm as the source of light. In certain blocks of trials, our subjects were encouraged to report as seen those trials in which the stimulus might have been present. It was determined that sensitivity and reliability were traded against each other over a broad range: for our subjects, the detection of 147 photons at the cornea with 60% frequency of seeing entailed, on the average, a 1% false-positive rate (FPR), whereas the detection of 34 photons at the cornea with 60% frequency of seeing was accompanied by a 33% FPR. A new neural-counting model has been developed in the framework of signal-detection theory. It combines Poisson stimulus fluctuations with additive and multiplicative neural noise, both of which are known to be present in the visual system at threshold. The resulting probability-of-detection curves, derived from the Neyman Type-A counting distribution, are in good accord with our experimental frequency-of-seeing data for sensible values of the model parameters. We deduce that, on the average, our four subjects are able to detect a single photon at the retina with 60% frequency of seeing, at the expense of a 55% FPR. In Part 2 of this set of papers [P.R. Prucnal and M.C. Teich, Biol. Cybern. 43, 87-96 (1982)], we use the normalizing transform, together with probit analysis, to provide improved estimates of threshold parameters, whereas in Part 3 [M.C. Teich, P.R. Prucnal, G. Vannucci, M.E. Breton, and W.J. McGill, submitted to Biol. Cybern.], we consider the effects of non-Poisson quantum fluctuations.

Adult↗
PubMed1994

[The unitary strategy of cancer cells: the hydrogen ion as a multidimensional unitary factor and carbohydrate metabolism (2)].

A systematic outlook of metabolism regarding the strategy followed by cancer cells is necessary in order to understand the thermodynamic advantages of these cells and the difficulty found in the treatment of certain malignant diseases. These features show that the present-day vision, the biochemical-analytical-fragmentary-reduccionistic approach, is not and it is not likely that it wil never be sufficient. Thus, a new paradigm of a different dimension but a the same time complementary to the previous and actual one seems necessary. Therefore, a higher and more comprehensive and outreaching vision, transbiochemical and metaenzymatic, one ecologically and macro and microenvironmentally oriented and finally synthetic and unitary one, appears mandatory. The dynamics of the hydrogen ion as applied to biological processes seems to be able to offer the opportunity to arrive to such kind of unifying comprehension through an integrated perceptive model at multiple levels of biological, biomedical and biophysical understanding.

Animals↗
PubMed1994

[Unitary strategy of cancerous cells: hydrocarbon metabolism (1)].

A systematic outlook of metabolism regarding the strategy followed by cancer cells is necessary in order to understand the thermodynamic advantages of these cells and the difficulty found in the treatment of certain malignant diseases. These features show that the present-day vision, the biochemical-analytical-fragmentary-reductionistic approach, is not and it is not likely that it will never be sufficient. Thus, a new paradigm of a different dimension but a the same time complementary to the previous and actual one seems necessary. Therefore, a higher and more comprehensive and outreaching vision, transbiochemical and metaenzymatic, one ecologically and macro and microenvironmentally oriented and finally synthetic and unitive one, appears mandatory. The dynamics of the hydrogen ion as applied to biological processes seems to be able to offer the opportunity to arrive to such kind of unifyng comprehension through and integrated perceptive model at multiple levels of biological, biomedical and biophysical understanding.

Animals↗
PubMed2001

Van Swieten and the renaissance of the Vienna Medical School.

The period until 1745 found the Viennese medical system languishing far behind advances made in other major European centers. This chaotic situation was reversed by the foresight and breadth of vision of the Empress Maria Theresa, who initiated considerable reform in Austria by actively recruiting the best minds of the time to reduce the intellectual and technologic differences. Her ability to entice one of Boerhaave's most eminent pupils, Gerard van Swieten, to leave Leiden for Vienna, particularly benefited the Vienna Medical School. In 1745 van Swieten assumed responsibility for reconfiguration of the patronage and nepotism-ridden medical system of the Austro-Hungarian Empire. As a first task, he swiftly expunged the influence of the Jesuits and other religious orders from medicine and established formal training and examinations, transforming the medical discipline into a meritocracy. Excelling as a physician and an innovative teacher, he also established a close personal relationship with the Empress and became her medical confidante. To a large part, the success of this first great Viennese medical school was owed to de Haen, who left Leiden to implement Boerhaave's method of clinical teaching. As a result of these innovations and with considerable support from the Empress, the University of Vienna, particularly its medical school, within a few decades achieved recognition throughout Europe as a seat of learning and scholarship. Van Swieten would not be remembered today if his contribution had been only scholarly or scientific achievements. He propelled Austrian medicine to a level commensurate with that of other European states of the day by 27 years of dedicated and industrious service.

Austria↗