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Sample records for stronger interocular contrast

  1. Contrast masking in strabismic amblyopia: attenuation, noise, interocular suppression and binocular summation.

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    Baker, Daniel H; Meese, Tim S; Hess, Robert F

    2008-07-01

    To investigate amblyopic contrast vision at threshold and above we performed pedestal-masking (contrast discrimination) experiments with a group of eight strabismic amblyopes using horizontal sinusoidal gratings (mainly 3c/deg) in monocular, binocular and dichoptic configurations balanced across eye (i.e. five conditions). With some exceptions in some observers, the four main results were as follows. (1) For the monocular and dichoptic conditions, sensitivity was less in the amblyopic eye than in the good eye at all mask contrasts. (2) Binocular and monocular dipper functions superimposed in the good eye. (3) Monocular masking functions had a normal dipper shape in the good eye, but facilitation was diminished in the amblyopic eye. (4) A less consistent result was normal facilitation in dichoptic masking when testing the good eye, but a loss of this when testing the amblyopic eye. This pattern of amblyopic results was replicated in a normal observer by placing a neutral density filter in front of one eye. The two-stage model of binocular contrast gain control [Meese, T.S., Georgeson, M.A. & Baker, D.H. (2006). Binocular contrast vision at and above threshold. Journal of Vision 6, 1224-1243.] was 'lesioned' in several ways to assess the form of the amblyopic deficit. The most successful model involves attenuation of signal and an increase in noise in the amblyopic eye, and intact stages of interocular suppression and binocular summation. This implies a behavioural influence from monocular noise in the amblyopic visual system as well as in normal observers with an ND filter over one eye.

  2. Interocular suppression in children with deprivation amblyopia.

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    Hamm, Lisa; Chen, Zidong; Li, Jinrong; Black, Joanna; Dai, Shuan; Yuan, Junpeng; Yu, Minbin; Thompson, Benjamin

    2017-04-01

    In patients with anisometropic or strabismic amblyopia, interocular suppression can be minimized by presenting high contrast stimulus elements to the amblyopic eye and lower contrast elements to the fellow eye. This suggests a structurally intact binocular visual system that is functionally suppressed. We investigated whether suppression can also be overcome by contrast balancing in children with deprivation amblyopia due to childhood cataracts. To quantify interocular contrast balance, contrast interference thresholds were measured using an established dichoptic global motion technique for 21 children with deprivation amblyopia, 14 with anisometropic or mixed strabismic/anisometropic amblyopia and 10 visually normal children (mean age mean=9.9years, range 5-16years). We found that interocular suppression could be overcome by contrast balancing in most children with deprivation amblyopia, at least intermittently, and all children with anisometropic or mixed anisometropic/strabismic amblyopia. However, children with deprivation amblyopia due to early unilateral or bilateral cataracts could tolerate only very low contrast levels to the stronger eye indicating strong suppression. Our results suggest that treatment options reliant on contrast balanced dichoptic presentation could be attempted in a subset of children with deprivation amblyopia. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Quantitative measurement of interocular suppression in children with amblyopia.

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    Narasimhan, Sathyasri; Harrison, Emily R; Giaschi, Deborah E

    2012-08-01

    In this study we explored the possibility of using a dichoptic global motion technique to measure interocular suppression in children with amblyopia. We compared children (5-16 years old) with unilateral anisometropic and/or strabismic amblyopia to age-matched control children. Under dichoptic viewing conditions, contrast interference thresholds were determined with a global motion direction-discrimination task. Using virtual reality goggles, high contrast signal dots were presented to the amblyopic eye, while low contrast noise dots were presented to the non-amblyopic fellow eye. The contrast of the noise dots was increased until discrimination of the motion direction of the signal dots reached chance performance. Contrast interference thresholds were significantly lower in the strabismic group than in the anisometropic and control group. Our results suggest that interocular suppression is stronger in strabismic than in anisometropic amblyopia. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Interocular suppression

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    Tuna, Ana Rita; Almeida Neves Carrega, Filipa; Nunes, Amélia Fernandes

    2017-08-01

    The objective of this work is to quantify the suppressive imbalance, based on the manipulation of ocular luminance, between a group of subjects with normal binocular vision and a group of subjects with amblyopia. The result reveals that there are statistically significant differences in interocular dominance between two groups, evidencing a greater suppressive imbalance in amblyopic subjects. The technique used, proved to be a simple, easy to apply and economic method, for quantified ocular dominance. It is presented as a technique with the potential to accompany subjects with a marked dominance in one of the eyes that makes fusion difficult.

  5. Chromatic interocular-switch rivalry.

    Science.gov (United States)

    Christiansen, Jens H; D'Antona, Anthony D; Shevell, Steven K

    2017-05-01

    Interocular-switch rivalry (also known as stimulus rivalry) is a kind of binocular rivalry in which two rivalrous images are swapped between the eyes several times a second. The result is stable periods of one image and then the other, with stable intervals that span many eye swaps (Logothetis, Leopold, & Sheinberg, 1996). Previous work used this close kin of binocular rivalry with rivalrous forms. Experiments here test whether chromatic interocular-switch rivalry, in which the swapped stimuli differ in only chromaticity, results in slow alternation between two colors. Swapping equiluminant rivalrous chromaticities at 3.75 Hz resulted in slow perceptual color alternation, with one or the other color often continuously visible for two seconds or longer (during which there were 15+ eye swaps). A well-known theory for sustained percepts from interocular-switch rivalry with form is inhibitory competition between binocular neurons driven by monocular neurons with matched orientation tuning in each eye; such binocular neurons would produce a stable response when a given orientation is swapped between the eyes. A similar model can account for the percepts here from chromatic interocular-switch rivalry and is underpinned by the neurophysiological finding that color-preferring binocular neurons are driven by monocular neurons from each eye with well-matched chromatic selectivity (Peirce, Solomon, Forte, & Lennie, 2008). In contrast to chromatic interocular-switch rivalry, luminance interocular-switch rivalry with swapped stimuli that differ in only luminance did not result in slowly alternating percepts of different brightnesses.

  6. Quantitative measurement of interocular suppression in anisometropic amblyopia: a case-control study.

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    Li, Jinrong; Hess, Robert F; Chan, Lily Y L; Deng, Daming; Yang, Xiao; Chen, Xiang; Yu, Minbin; Thompson, Benjamin

    2013-08-01

    The aims of this study were to assess (1) the relationship between interocular suppression and visual function in patients with anisometropic amblyopia, (2) whether suppression can be simulated in matched controls using monocular defocus or neutral density filters, (3) the effects of spectacle or rigid gas-permeable contact lens correction on suppression in patients with anisometropic amblyopia, and (4) the relationship between interocular suppression and outcomes of occlusion therapy. Case-control study (aims 1-3) and cohort study (aim 4). Forty-five participants with anisometropic amblyopia and 45 matched controls (mean age, 8.8 years for both groups). Interocular suppression was assessed using Bagolini striated lenses, neutral density filters, and an objective psychophysical technique that measures the amount of contrast imbalance between the 2 eyes that is required to overcome suppression (dichoptic motion coherence thresholds). Visual acuity was assessed using a logarithm minimum angle of resolution tumbling E chart and stereopsis using the Randot preschool test. Interocular suppression assessed using dichoptic motion coherence thresholds. Patients exhibited significantly stronger suppression than controls, and stronger suppression was correlated significantly with poorer visual acuity in amblyopic eyes. Reducing monocular acuity in controls to match that of cases using neutral density filters (luminance reduction) resulted in levels of interocular suppression comparable with that in patients. This was not the case for monocular defocus (optical blur). Rigid gas-permeable contact lens correction resulted in less suppression than spectacle correction, and stronger suppression was associated with poorer outcomes after occlusion therapy. Interocular suppression plays a key role in the visual deficits associated with anisometropic amblyopia and can be simulated in controls by inducing a luminance difference between the eyes. Accurate quantification of suppression

  7. Deconstructing Interocular Suppression: Attention and Divisive Normalization.

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    Hsin-Hung Li

    2015-10-01

    Full Text Available In interocular suppression, a suprathreshold monocular target can be rendered invisible by a salient competitor stimulus presented in the other eye. Despite decades of research on interocular suppression and related phenomena (e.g., binocular rivalry, flash suppression, continuous flash suppression, the neural processing underlying interocular suppression is still unknown. We developed and tested a computational model of interocular suppression. The model included two processes that contributed to the strength of interocular suppression: divisive normalization and attentional modulation. According to the model, the salient competitor induced a stimulus-driven attentional modulation selective for the location and orientation of the competitor, thereby increasing the gain of neural responses to the competitor and reducing the gain of neural responses to the target. Additional suppression was induced by divisive normalization in the model, similar to other forms of visual masking. To test the model, we conducted psychophysics experiments in which both the size and the eye-of-origin of the competitor were manipulated. For small and medium competitors, behavioral performance was consonant with a change in the response gain of neurons that responded to the target. But large competitors induced a contrast-gain change, even when the competitor was split between the two eyes. The model correctly predicted these results and outperformed an alternative model in which the attentional modulation was eye specific. We conclude that both stimulus-driven attention (selective for location and feature and divisive normalization contribute to interocular suppression.

  8. Deconstructing Interocular Suppression: Attention and Divisive Normalization.

    Science.gov (United States)

    Li, Hsin-Hung; Carrasco, Marisa; Heeger, David J

    2015-10-01

    In interocular suppression, a suprathreshold monocular target can be rendered invisible by a salient competitor stimulus presented in the other eye. Despite decades of research on interocular suppression and related phenomena (e.g., binocular rivalry, flash suppression, continuous flash suppression), the neural processing underlying interocular suppression is still unknown. We developed and tested a computational model of interocular suppression. The model included two processes that contributed to the strength of interocular suppression: divisive normalization and attentional modulation. According to the model, the salient competitor induced a stimulus-driven attentional modulation selective for the location and orientation of the competitor, thereby increasing the gain of neural responses to the competitor and reducing the gain of neural responses to the target. Additional suppression was induced by divisive normalization in the model, similar to other forms of visual masking. To test the model, we conducted psychophysics experiments in which both the size and the eye-of-origin of the competitor were manipulated. For small and medium competitors, behavioral performance was consonant with a change in the response gain of neurons that responded to the target. But large competitors induced a contrast-gain change, even when the competitor was split between the two eyes. The model correctly predicted these results and outperformed an alternative model in which the attentional modulation was eye specific. We conclude that both stimulus-driven attention (selective for location and feature) and divisive normalization contribute to interocular suppression.

  9. Visual functions and interocular interactions in anisometropic children with and without amblyopia.

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    Lai, Xin Jie; Alexander, Jack; He, Mingguang; Yang, Zhikuan; Suttle, Catherine

    2011-08-29

    In uncorrected anisometropia, protracted dichoptic stimulation may result in interocular inhibition, which may be a contributing factor in amblyopia development. This study investigates the relationship between interocular interactions and anisometropic amblyopia. Three visual functions (low-contrast acuity, contrast sensitivity, and alignment sensitivity) were measured in the nondominant eye of 44 children aged 5 to 11 years: 10 with normal vision, 17 with anisometropia without amblyopia, and 17 with anisometropic amblyopia. The dominant eye was either fully or partially occluded. The difference in nondominant eye visual function between the full-and partial-occlusion conditions was termed the interaction index. The index of each visual function was compared between subject groups. A higher index indicates stronger inhibition of nondominant eye function with partial occlusion of the dominant eye. Amblyopic children had 6 months of therapy (refractive correction and occlusion), and the reduction in interocular difference in high-contrast acuity was regarded as the treatment outcome. The relationships of the interaction index with the degree of anisometropia, the severity of amblyopia, and the treatment outcomes were examined. The acuity interaction index was significantly higher in anisometropic children with amblyopia than in those without (P = 0.003). It was positively correlated with the degree of anisometropia (r(s) = 0.35, P = 0.042) and the amblyopic treatment outcomes (r(s) = 0.54, P = 0.038). No such difference or association was found between the contrast sensitivity or alignment sensitivity interaction index and anisometropic amblyopia. Interocular interactions are associated with amblyopia, the degree of anisometropia, and amblyopia treatment outcomes, but these associations are visual function dependent.

  10. Interocular suppression in amblyopia for global orientation processing.

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    Zhou, Jiawei; Huang, Pi-Chun; Hess, Robert F

    2013-04-22

    We developed a dichoptic global orientation coherence paradigm to quantify interocular suppression in amblyopia. This task is biased towards ventral processing and allows comparison with two other techniques-global motion processing, which is more dorsally biased, and binocular phase combination, which most likely reflects striate function. We found a similar pattern for the relationship between coherence threshold and interocular contrast curves (thresholds vs. interocular contrast ratios or TvRs) in our new paradigm compared with those of the previous dichoptic global motion coherence paradigm. The effective contrast ratios at balance point (where the signals from the two eyes have equal weighting) in our new paradigm were larger than those of the dichoptic global motion coherence paradigm but less than those of the binocular phase combination paradigm. The measured effective contrast ratios in the three paradigms were also positively correlated with each other, with the two global coherence paradigms having the highest correlation. We concluded that: (a) The dichoptic global orientation coherence paradigm is effective in quantifying interocular suppression in amblyopia; and (b) Interocular suppression, while sharing a common suppression mechanism at the early stage in the pathway (e.g., striate cortex), may have additional extra-striate contributions that affect both dorsal and ventral streams differentially.

  11. Monocular Perceptual Deprivation from Interocular Suppression Temporarily Imbalances Ocular Dominance.

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    Kim, Hyun-Woong; Kim, Chai-Youn; Blake, Randolph

    2017-03-20

    Early visual experience sculpts neural mechanisms that regulate the balance of influence exerted by the two eyes on cortical mechanisms underlying binocular vision [1, 2], and experience's impact on this neural balancing act continues into adulthood [3-5]. One recently described, compelling example of adult neural plasticity is the effect of patching one eye for a relatively short period of time: contrary to intuition, monocular visual deprivation actually improves the deprived eye's competitive advantage during a subsequent period of binocular rivalry [6-8], the robust form of visual competition prompted by dissimilar stimulation of the two eyes [9, 10]. Neural concomitants of this improvement in monocular dominance are reflected in measurements of brain responsiveness following eye patching [11, 12]. Here we report that patching an eye is unnecessary for producing this paradoxical deprivation effect: interocular suppression of an ordinarily visible stimulus being viewed by one eye is sufficient to produce shifts in subsequent predominance of that eye to an extent comparable to that produced by patching the eye. Moreover, this imbalance in eye dominance can also be induced by prior, extended viewing of two monocular images differing only in contrast. Regardless of how shifts in eye dominance are induced, the effect decays once the two eyes view stimuli equal in strength. These novel findings implicate the operation of interocular neural gain control that dynamically adjusts the relative balance of activity between the two eyes [13, 14]. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Stronger synergies

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    CERN was founded 58 years ago under the auspices of UNESCO. Since then, both organisations have grown to become world leaders in their respective fields. The links between the two have always existed but today they are even stronger, with new projects under way to develop a more efficient way of exchanging information and devise a common strategy on topics of mutual interest.   CERN and UNESCO are a perfect example of natural partners: their common field is science and education is one of the pillars on which both are built. Historically, they share a common heritage. Both UNESCO and CERN were born of the desire to use scientific cooperation to rebuild peace and security in the aftermath of the Second World War. "Recently, building on our common roots and in close collaboration with UNESCO, we have been developing more structured links to ensure the continuity of the actions taken over the years," says Maurizio Bona, who is in charge of CERN relations with international orga...

  13. The perceptual consequences of interocular suppression in amblyopia.

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    Maehara, Goro; Thompson, Benjamin; Mansouri, Behzad; Farivar, Reza; Hess, Robert F

    2011-11-21

    It is known that information from an amblyopic eye can be strongly suppressed when both eyes are open. The authors investigated the way in which suppression influences the relative perception of suprathreshold contrast and luminance between a person's eyes under dichoptic viewing conditions. Stimuli consisted of four patches of luminance or four patches containing gratings. Two patches were presented to each eye. Ten amblyopes with mild suppression (six strabismic, three anisometropic and strabismic, and one deprivation; mean age, 34.5 years) and three control observers with normal vision (mean age, 33.0 years) matched the appearance of the stimuli presented to each eye. The match involved manipulation of either luminance or contrast. Amblyopes with mild suppression decreased stimulus luminance in the fellow fixing eye or increased luminance in the amblyopic eye to achieve a match (mean matching luminance, 21.1 and 39.6 cd/m(2) for the fellow fixing eye and the amblyopic eye, respectively; standard luminance, 30 cd/m(2)). This interocular mismatch was also observed when luminance was variable and contrast was kept constant (mean matching luminance, 22.8 cd/m(2) for the fellow fixing eye). On the other hand, the amblyopic eye showed no loss of perceived contrast. There was little or no mismatch between the two eyes of control participants with normal binocular vision. Amblyopes have monocular deficits in contrast perception but dichoptic deficits in luminance perception, suggesting that suppression in its mild form involves luminance processing.

  14. Transient improvements in fixational stability in strabismic amblyopes following bifoveal fixation and reduced interocular suppression.

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    Raveendran, Rajkumar Nallour; Babu, Raiju J; Hess, Robert F; Bobier, William R

    2014-03-01

    To test the hypothesis that fixational stability of the amblyopic eye in strabismics will improve when viewing provides both bifoveal fixation and reduced inter-ocular suppression by reducing the contrast to the fellow eye. Seven strabismic amblyopes (Age: 29.2 ± 9 years; five esotropes and two exotropes) showing clinical characteristics of central suppression were recruited. Interocular suppression was measured by a global motion task. For each participant, a balance point was determined which defined contrast levels for each eye where binocular combination was optimal (interocular suppression minimal). When the balance point could not be determined, this participant was excluded. Bifoveal fixation was established by ocular alignment using a haploscope. Participants dichoptically viewed similar targets (a cross of 2.3° surrounded by a square of 11.3°) at 40 cm. Target contrasts presented to each eye were either high contrast (100% to both eyes) or balanced contrast (attenuated contrast in the fellow fixing eye). Fixation stability was measured over a 5 min period and quantified using bivariate contour ellipse areas in four different binocular conditions; unaligned/high contrast, unaligned/balance point, aligned/high contrast and aligned/balance point. Fixation stability was also measured in six control subjects (Age: 25.3 ± 4 years). Bifoveal fixation in the strabismics was transient (58.15 ± 15.7 s). Accordingly, fixational stability was analysed over the first 30 s using repeated measures anova. Post hoc analysis revealed that for the amblyopic subjects, the fixational stability of the amblyopic eye was significantly improved in aligned/high contrast (p = 0.01) and aligned/balance point (p suppression. However, once initiated, bifoveal fixation is transient with the strabismic eye drifting away from foveal alignment, thereby increasing the angle of strabismus. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

  15. Psychophysical research progress of interocular suppression in amblyopic visual system

    OpenAIRE

    Jing-Jing Li; Yi Huang

    2016-01-01

    Some recent animal experiments and psychophysical studies indicate that patients with amblyopia have a structurally intact binocular visual system that is rendered functionally monocular due to suppression, and interocular suppression is a key mechanism in visual deficits experienced by patients with amblyopia. The aim of this review is to provide an overview of recent psychophysical findings that have investigated the important role of interocular suppression in amblyopia, the measurement an...

  16. Binocular neurons in parastriate cortex: interocular 'matching' of receptive field properties, eye dominance and strength of silent suppression.

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    Phillip A Romo

    Full Text Available Spike-responses of single binocular neurons were recorded from a distinct part of primary visual cortex, the parastriate cortex (cytoarchitectonic area 18 of anaesthetized and immobilized domestic cats. Functional identification of neurons was based on the ratios of phase-variant (F1 component to the mean firing rate (F0 of their spike-responses to optimized (orientation, direction, spatial and temporal frequencies and size sine-wave-luminance-modulated drifting grating patches presented separately via each eye. In over 95% of neurons, the interocular differences in the phase-sensitivities (differences in F1/F0 spike-response ratios were small (≤ 0.3 and in over 80% of neurons, the interocular differences in preferred orientations were ≤ 10°. The interocular correlations of the direction selectivity indices and optimal spatial frequencies, like those of the phase sensitivies and optimal orientations, were also strong (coefficients of correlation r ≥ 0.7005. By contrast, the interocular correlations of the optimal temporal frequencies, the diameters of summation areas of the excitatory responses and suppression indices were weak (coefficients of correlation r ≤ 0.4585. In cells with high eye dominance indices (HEDI cells, the mean magnitudes of suppressions evoked by stimulation of silent, extra-classical receptive fields via the non-dominant eyes, were significantly greater than those when the stimuli were presented via the dominant eyes. We argue that the well documented 'eye-origin specific' segregation of the lateral geniculate inputs underpinning distinct eye dominance columns in primary visual cortices of mammals with frontally positioned eyes (distinct eye dominance columns, combined with significant interocular differences in the strength of silent suppressive fields, putatively contribute to binocular stereoscopic vision.

  17. Psychophysical research progress of interocular suppression in amblyopic visual system

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    Jing-Jing Li

    2016-03-01

    Full Text Available Some recent animal experiments and psychophysical studies indicate that patients with amblyopia have a structurally intact binocular visual system that is rendered functionally monocular due to suppression, and interocular suppression is a key mechanism in visual deficits experienced by patients with amblyopia. The aim of this review is to provide an overview of recent psychophysical findings that have investigated the important role of interocular suppression in amblyopia, the measurement and modulation of suppression, and new dichoptic treatment intervention that directly target suppression.

  18. Velocity dependence of the interocular transfer of dynamic motion afteraffects

    NARCIS (Netherlands)

    Tao, R.; Lankheet, M.J.M.; van de Grind, W.A.V.; Wezel, R.J.A. van

    2002-01-01

    It is well established that motion aftereffects (MAEs) can show interocular transfer (IOT); that is, motion adaptation in one eye can give a MAE in the other eye. Different quantification methods and different test stimuli have been shown to give different IOT magnitudes, varying from no to almost

  19. Velocity dependence of the interocular transfer of dynamic motion aftereffects

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    Tao, R.; Lankheet, M.J.M.; Wezel, R.J.A. van

    2003-01-01

    It is well established that motion aftereffects (MAEs) can show interocular transfer (IOT); that is, motion adaptation in one eye can give a MAE in the other eye. Different quantification methods and different test stimuli have been shown to give different IOT magnitudes, varying from no to almost

  20. Eye contact facilitates awareness of faces during interocular suppression

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    Stein, T.; Senju, A.; Peelen, M.V.; Sterzer, P.

    Eye contact captures attention and receives prioritized visual processing. Here we asked whether eye contact might be processed outside conscious awareness. Faces with direct and averted gaze were rendered invisible using interocular suppression. In two experiments we found that faces with direct

  1. Interocular agreement in melanin and macular pigment optical density.

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    Kanis, M.J.; Berendschot, T.T.J.M.; van Norren, D.

    2007-01-01

    Macular pigment (MP) and melanin possibly protect the macular area by absorbing blue light and acting as antioxidants. Because little is known about the interocular correlation of melanin, we determined its optical density (MOD) in both eyes of healthy subjects using fundus reflectometry. The

  2. Interocular Symmetry in Macular Choroidal Thickness in Children

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    Christiane Al-Haddad

    2014-01-01

    Full Text Available Objective. To report interocular differences in choroidal thickness in children using spectral domain optical coherence tomography (SD-OCT and correlate findings with biometric data. Methods. This observational cross-sectional study included 91 (182 eyes healthy children aged 6 to 17 years with no ocular abnormality except refractive error. After a comprehensive eye exam and axial length measurement, high definition macular scans were performed using SD-OCT. Two observers manually measured the choroidal thickness at the foveal center and at 1500 µm nasally, temporally, inferiorly, and superiorly. Interocular differences were computed; correlations with age, gender, refractive error, and axial length were performed. Results. Mean age was 10.40 ± 3.17 years; mean axial length and refractive error values were similar between fellow eyes. There was excellent correlation between the two observers’ measurements. No significant interocular differences were observed at any location. There was only a trend for right eyes to have higher values in all thicknesses, except the superior thickness. Most of the choroidal thickness measurements correlated positively with spherical equivalent but not with axial length, age, or gender. Conclusion. Choroidal thickness measurements in children as performed using SD-OCT revealed a high level of interobserver agreement and consistent interocular symmetry. Values correlated positively with spherical equivalent refraction.

  3. Interocular symmetry in macular choroidal thickness in children.

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    Al-Haddad, Christiane; El Chaar, Lama; Antonios, Rafic; El-Dairi, Mays; Noureddin, Baha'

    2014-01-01

    Objective. To report interocular differences in choroidal thickness in children using spectral domain optical coherence tomography (SD-OCT) and correlate findings with biometric data. Methods. This observational cross-sectional study included 91 (182 eyes) healthy children aged 6 to 17 years with no ocular abnormality except refractive error. After a comprehensive eye exam and axial length measurement, high definition macular scans were performed using SD-OCT. Two observers manually measured the choroidal thickness at the foveal center and at 1500 µm nasally, temporally, inferiorly, and superiorly. Interocular differences were computed; correlations with age, gender, refractive error, and axial length were performed. Results. Mean age was 10.40 ± 3.17 years; mean axial length and refractive error values were similar between fellow eyes. There was excellent correlation between the two observers' measurements. No significant interocular differences were observed at any location. There was only a trend for right eyes to have higher values in all thicknesses, except the superior thickness. Most of the choroidal thickness measurements correlated positively with spherical equivalent but not with axial length, age, or gender. Conclusion. Choroidal thickness measurements in children as performed using SD-OCT revealed a high level of interobserver agreement and consistent interocular symmetry. Values correlated positively with spherical equivalent refraction.

  4. Eye Contact Facilitates Awareness of Faces during Interocular Suppression

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    Stein, Timo; Senju, Atsushi; Peelen, Marius V.; Sterzer, Philipp

    2011-01-01

    Eye contact captures attention and receives prioritized visual processing. Here we asked whether eye contact might be processed outside conscious awareness. Faces with direct and averted gaze were rendered invisible using interocular suppression. In two experiments we found that faces with direct gaze overcame such suppression more rapidly than…

  5. Interocular transfer of spatial adaptation is weak at low spatial frequencies.

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    Baker, Daniel H; Meese, Tim S

    2012-06-15

    Adapting one eye to a high contrast grating reduces sensitivity to similar target gratings shown to the same eye, and also to those shown to the opposite eye. According to the textbook account, interocular transfer (IOT) of adaptation is around 60% of the within-eye effect. However, most previous studies on this were limited to using high spatial frequencies, sustained presentation, and criterion-dependent methods for assessing threshold. Here, we measure IOT across a wide range of spatiotemporal frequencies, using a criterion-free 2AFC method. We find little or no IOT at low spatial frequencies, consistent with other recent observations. At higher spatial frequencies, IOT was present, but weaker than previously reported (around 35%, on average, at 8c/deg). Across all conditions, monocular adaptation raised thresholds by around a factor of 2, and observers showed normal binocular summation, demonstrating that they were not binocularly compromised. These findings prompt a reassessment of our understanding of the binocular architecture implied by interocular adaptation. In particular, the output of monocular channels may be available to perceptual decision making at low spatial frequencies. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Investigating category- and shape-selective neural processing in ventral and dorsal visual stream under interocular suppression.

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    Ludwig, Karin; Kathmann, Norbert; Sterzer, Philipp; Hesselmann, Guido

    2015-01-01

    Recent behavioral and neuroimaging studies using continuous flash suppression (CFS) have suggested that action-related processing in the dorsal visual stream might be independent of perceptual awareness, in line with the "vision-for-perception" versus "vision-for-action" distinction of the influential dual-stream theory. It remains controversial if evidence suggesting exclusive dorsal stream processing of tool stimuli under CFS can be explained by their elongated shape alone or by action-relevant category representations in dorsal visual cortex. To approach this question, we investigated category- and shape-selective functional magnetic resonance imaging-blood-oxygen level-dependent responses in both visual streams using images of faces and tools. Multivariate pattern analysis showed enhanced decoding of elongated relative to non-elongated tools, both in the ventral and dorsal visual stream. The second aim of our study was to investigate whether the depth of interocular suppression might differentially affect processing in dorsal and ventral areas. However, parametric modulation of suppression depth by varying the CFS mask contrast did not yield any evidence for differential modulation of category-selective activity. Together, our data provide evidence for shape-selective processing under CFS in both dorsal and ventral stream areas and, therefore, do not support the notion that dorsal "vision-for-action" processing is exclusively preserved under interocular suppression. © 2014 Wiley Periodicals, Inc.

  7. Experience-induced interocular plasticity of vision in infancy

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    Wayne eTschetter

    2011-06-01

    Full Text Available Animal model studies of amblyopia have generally found that enduring effects of monocular deprivation (MD on visual behavior (i.e. loss of visual acuity are limited to the deprived eye, and are restricted to juvenile life. We have previously reported, however, that lasting effects of MD on visual function can be elicited in adulthood by stimulating visuomotor experience through the non-deprived eye. To test whether visuomotor experience would also induce interocular plasticity of vision in infancy, we assessed in rats from eye opening on postnatal day (P15, the effect of pairing MD with daily threshold measurements of opto-kinetic tracking (OKT. Combining MD with OKT experience up to P25 led to a ~60% enhancement of the spatial frequency threshold through the non-deprived eye for OKT during the MD, which was followed by loss of function (~60% below normal through both eyes when the deprived eye was opened. Strictly limiting the period of deprivation to infancy, by opening the deprived eye at P19, resulted in comparable loss of function. Thresholds recovered by P30 unless binocular OKT experience was stimulated through both eyes from P25-P30, which was sufficient to maintain the lost function indefinitely. The ability to generate the plasticity, as well as to maintain lost function, was dependent on visual cortex. Animals with reduced visuomotor thresholds also exhibited significantly reduced visual acuity, measured independently in a discrimination task. Thus, a form of interocular plasticity, in which the stimulation of visual experience during MD can induce amblyopia, is present before the beginning of juvenile life.

  8. Monocular deprivation of Fourier phase information boosts the deprived eye's dominance during interocular competition but not interocular phase combination.

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    Bai, Jianying; Dong, Xue; He, Sheng; Bao, Min

    2017-06-03

    Ocular dominance has been extensively studied, often with the goal to understand neuroplasticity, which is a key characteristic within the critical period. Recent work on monocular deprivation, however, demonstrates residual neuroplasticity in the adult visual cortex. After deprivation of patterned inputs by monocular patching, the patched eye becomes more dominant. Since patching blocks both the Fourier amplitude and phase information of the input image, it remains unclear whether deprivation of the Fourier phase information alone is able to reshape eye dominance. Here, for the first time, we show that removing of the phase regularity without changing the amplitude spectra of the input image induced a shift of eye dominance toward the deprived eye, but only if the eye dominance was measured with a binocular rivalry task rather than an interocular phase combination task. These different results indicate that the two measurements are supported by different mechanisms. Phase integration requires the fusion of monocular images. The fused percept highly relies on the weights of the phase-sensitive monocular neurons that respond to the two monocular images. However, binocular rivalry reflects the result of direct interocular competition that strongly weights the contour information transmitted along each monocular pathway. Monocular phase deprivation may not change the weights in the integration (fusion) mechanism much, but alters the balance in the rivalry (competition) mechanism. Our work suggests that ocular dominance plasticity may occur at different stages of visual processing, and that homeostatic compensation also occurs for the lack of phase regularity in natural scenes. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  9. Experience-induced interocular plasticity of vision in infancy.

    Science.gov (United States)

    Tschetter, Wayne W; Douglas, Robert M; Prusky, Glen T

    2011-01-01

    Animal model studies of amblyopia have generally concluded that enduring effects of monocular deprivation (MD) on visual behavior (i.e., loss of visual acuity) are limited to the deprived eye, and are restricted to juvenile life. We have previously reported, however, that lasting effects of MD on visual function can be elicited in adulthood by stimulating visuomotor experience through the non-deprived eye. To test whether stimulating experience would also induce interocular plasticity of vision in infancy, we assessed in rats from eye-opening on postnatal day (P) 15, the effect of pairing MD with the daily experience of measuring thresholds for optokinetic tracking (OKT). MD with visuomotor experience from P15 to P25 led to a ~60% enhancement of the spatial frequency threshold for OKT through the non-deprived eye during the deprivation, which was followed by loss-of-function (~60% below normal) through both eyes when the deprived eye was opened. Reduced thresholds were maintained into adulthood with binocular OKT experience from P25 to P30. The ability to generate the plasticity and maintain lost function was dependent on visual cortex. Strictly limiting the period of deprivation to infancy by opening the deprived eye at P19 resulted in a comparable loss-of-function. Animals with reduced OKT responses also had significantly reduced visual acuity, measured independently in a discrimination task. Thus, experience-dependent cortical plasticity that can lead to amblyopia is present earlier in life than previously recognized.

  10. Stronger Fire-Resistant Epoxies

    Science.gov (United States)

    Fohlen, George M.; Parker, John A.; Kumar, Devendra

    1988-01-01

    New curing agent improves mechanical properties and works at lower temperature. Use of aminophenoxycyclotriphosphazene curing agents yields stronger, more heat- and fire-resistant epoxy resins. Used with solvent if necessary for coating fabrics or casting films.

  11. Dynamics of Interocular Suppression in Amblyopic Children during Electronically Monitored Occlusion Therapy: First Insight.

    Science.gov (United States)

    Kehrein, Stephan; Kohnen, Thomas; Fronius, Maria

    2016-06-01

    Interocular suppression is assumed to be the mechanism leading to impaired visual acuity, especially in strabismic amblyopia. Little is known about the dynamics of suppression during treatment. The aim of our study was to assess the development of the depth of suppression and its relation to changes in visual acuity during electronically monitored occlusion treatment. In a prospective pilot study, 15 amblyopes (8 with and 7 without strabismus) aged 5 to 16 years (mean 10.24 years) were examined before initiation of patching and then every 3 to 6 weeks for 4 months. To quantify suppression, a red filter ladder (Sbisa bar) was used, attenuating the image of the dominant eye until the patients reported a binocular perception (diplopia, rivalry, color mixture) or a change in eye dominance. Acuity was assessed with crowded Landolt rings. Daily occlusion was recorded using occlusion dose monitors. The depth of interocular suppression showed a biphasic change: it increased significantly during the first month (P=0.02), while visual acuity improved (mean 0.14 log units ±0.13; Pocclusion and suppression changes was not statistically significant. This first insight into the functional changes during electronically monitored patching suggests a complex relationship between visual acuity and interocular suppression that seems to be influenced by the presence of strabismus. Knowledge of the dynamics of interocular suppression is crucial for enhancing the outcome of occlusion treatment and also for the evaluation of its future role compared to emerging dichoptic treatments.

  12. Prospects for stronger calandria tubes

    International Nuclear Information System (INIS)

    Ells, C.E.; Coleman, C.E.; Hosbons, R.R.; Ibrahim, E.F.; Doubt, G.L.

    1990-12-01

    The CANDU calandria tubes, made of seam welded and annealed Zircaloy-2, have given exemplary service in-reactor. Although not designed as a system pressure containment, calandria tubes may remain intact even in the face of pressure tube rupture. One such incident at Pickering Unit 2 demonstrated the economic advantage of such an outcome, and a case can be made for increasing the probability that other calandria tubes would perform in a similar fashion. Various methods of obtaining stronger calandria tubes are available, and reviewed here. When the tubes are internally pressurized, the weld is the weak section of the tube. Increasing the oxygen concentration in the starting sheet, and thickening the weld, are promising routes to a stronger tube

  13. Interocular difference and duration for doubling of the minimal angle of visual resolution in patients with Stargardt disease.

    Science.gov (United States)

    Hajali, Manal; Fishman, Gerald A; Anderson, Robert J; McAnany, J Jason

    2009-07-01

    To determine the extent of interocular difference in visual acuity (VA) and the time to at least double the minimal angle of resolution (MAR) in a cohort of patients with Stargardt disease. One hundred fifty patients with Stargardt disease who were examined at least four times over a minimum period of 3 years were identified and their VA and age at each visit recorded. The maximum interocular difference of VA was determined by whether the MAR between the two eyes differed by less than a factor of 2 or by a factor of 2 or greater. Differences in maximum VA between the two eyes were also examined according to a Bland-Altman-type approach. One hundred thirty-one eyes from 76 patients were subjected to survival analysis to determine whether the time to at least double the MAR was dependent on age at baseline or starting VA. Of the 150 patients, 48% had interocular MAR that differed maximally by a factor of less than 2. Thirty-five percent showed a maximum interocular difference in their Snellen VA of less than one line. The Bland-Altman- type analysis showed that maximum interocular acuity difference was dependent on the mean acuity of the two eyes. The hazard for at least doubling the MAR was related to baseline vision and patient age. This information has clinical significance for patient counseling and for monitoring possible benefits and patient selection in future treatment trials.

  14. Interocular asymmetry of the visual field defects in newly diagnosed normal-tension glaucoma, primary open-angle glaucoma, and chronic angle-closure glaucoma.

    Science.gov (United States)

    Huang, Ping; Shi, Yan; Wang, Xin; Liu, Mugen; Zhang, Chun

    2014-09-01

    To compare the interocular asymmetry of visual field loss in newly diagnosed normal-tension glaucoma (NTG), primary open-angle glaucoma (POAG), and chronic angle-closure glaucoma (CACG) patients. Visual field results of 117 newly diagnosed, treatment-naive glaucoma patients (42 NTG, 38 POAG, and 37 CACG) were studied retrospectively. The following 3 visual field defect parameters were used to evaluate the interocular asymmetry: (1) global indices; (2) local mean deviations (MDs) of 6 predefined visual field areas; and (3) stage designated by glaucoma staging system 2. The differences of the above parameters between the trial eye (the eye with greater MDs) and the fellow eye in each subject were defined as interocular asymmetry scores. Interocular asymmetry of visual field loss was presented in all the 3 groups (all P0.05). Interocular asymmetry scores of glaucoma staging system 2 had no significant difference among the 3 groups (P=0.068). All CACG, POAG, and NTG groups presented with interocular asymmetric visual field loss at the time of diagnosis. CACG had greater interocular asymmetry compared with NTG and POAG. No significant interocular asymmetry difference was observed between NTG and POAG.

  15. Strategy and your stronger hand.

    Science.gov (United States)

    Moore, Geoffrey A

    2005-12-01

    There are two kinds of businesses in the world, says the author. Knowing what they are--and which one your company is--will guide you to the right strategic moves. One kind includes businesses that compete on a complex-systems model. These companies have large enterprises as their primary customers. They seek to grow a customer base in the thousands, with no more than a handful of transactions per customer per year (indeed, in some years there may be none), and the average price per transaction ranges from six to seven figures. In this model, 1,000 enterprises each paying dollar 1 million per year would generate dollar 1 billion in annual revenue. The other kind of business competes on a volume-operations model. Here, vendors seek to acquire millions of customers, with tens or even hundreds of transactions per customer per year, at an average price of relatively few dollars per transaction. Under this model, it would take 10 million customers each spending dollar 8 per month to generate nearly dollar 1 billion in revenue. An examination of both models shows that they could not be further apart in their approach to every step along the classic value chain. The problem, though, is that companies in one camp often attempt to create new value by venturing into the other. In doing so, they fail to realize how their managerial habits have been shaped by the model they've grown up with. By analogy, they have a "handedness"--the equivalent of a person's right- or left-hand dominance--that makes them as adroit in one mode as they are awkward in the other. Unless you are in an industry whose structure forces you to attempt ambidexterity (in which case, special efforts are required to manage the inevitable dropped balls), you'll be far more successful making moves that favor your stronger hand.

  16. Waves of visibility: probing the depth of inter-ocular suppression with transient and sustained targets

    Directory of Open Access Journals (Sweden)

    Lisandro eKaunitz

    2014-07-01

    Full Text Available In order to study non-conscious visual processing, researchers render otherwise consciously perceived images into invisible stimuli. Through the years, several psychophysical techniques have been developed for this purpose. Yet the comparison of experimental results across techniques remains a difficult task as the depth of suppression depends on the interactions between the type of stimuli and the suppression methods employed. This poses a limit to the inferences that researchers make about the extent of non-conscious processes. We investigated the mechanisms underlying inter-ocular suppression during continuous flash suppression (CFS and dichoptic visual masking using a transient onset target stimulus and a variety of stimulus / mask temporal manipulations. We show that target duration, timing of target onset, and mask frequency are key aspects of inter-ocular suppression during CFS with transient targets. The differences between our results and sustained target CFS studies suggest that two distinct mechanisms are involved in the detection of transient and prolonged target stimuli during CFS. Our results provide insight into the dynamics of CFS together with evidence for similarities between transient target CFS and dichoptic visual masking.

  17. Female Psychology in August Strindberg's the Stronger

    OpenAIRE

    Sutandio, Anton; Apriliani, Erica

    2017-01-01

    This research aimed to offer interpretations of August Strindberg's The Stronger through the lens of female psychology. The Stronger is unique as it seemed very simple yet so intense and powerful with layers of interpretations. Written during 1888-1889, The Stronger, which only had two characters and only one speaking character, had become one of Strindberg's shortest yet important plays during his career. The female psychology approach used in the analysis would cover the discussion of gende...

  18. Breaking continuous flash suppression: A new measure of unconscious processing during interocular suppression?

    Directory of Open Access Journals (Sweden)

    Timo eStein

    2011-12-01

    Full Text Available Until recently, it has been thought that under interocular suppression high-level visual processing is strongly inhibited if not abolished. With the development of continuous flash suppression (CFS, a variant of binocular rivalry, this notion has now been challenged by a number of reports showing that even high-level aspects of visual stimuli, such as familiarity, affect the time stimuli need to overcome CFS and emerge into awareness. In this breaking CFS (b-CFS paradigm, differential unconscious processing during suppression is inferred when (a speeded detection responses to initially invisible stimuli differ, and (b no comparable differences are found in non-rivalrous control conditions supposed to measure general threshold differences between stimuli. To critically evaluate these assumptions was the aim of the present study. In six experiments we compared the time upright and inverted faces needed to be detected. We found that not only under CFS, but also in control conditions upright faces were detected faster and more accurately than inverted faces, although the effect was larger during CFS. However, reaction time (RT distributions indicated critical differences between the CFS and the control condition. When RT distributions were matched, similar effect sizes were obtained in both conditions. Moreover, subjective ratings revealed that CFS and control conditions are not perceptually comparable. These findings cast doubt on the usefulness of non-rivalrous control conditions to rule out mere detection threshold differences as a cause of shorter detection latencies during CFS. In conclusion, we acknowledge that the b-CFS paradigm can be fruitfully applied as a highly sensitive device to probe differences between stimuli in their potency to gain access to awareness. However, our current findings suggest that such differences can not unequivocally be attributed to differential unconscious processing under interocular suppression.

  19. P1-13: Color Induction from Surround Color under Interocular Suppression

    Directory of Open Access Journals (Sweden)

    Ichiro Kuriki

    2012-10-01

    Full Text Available The effect of surround colors on color appearance is known to subserve color constancy in humans, but how multiple mechanisms in the visual system are involved in this effect is controversial. We used an interocular-suppression technique to examine how the effect occurs at the level higher than the interaction of binocular information. A test color chip (1.7 × 1.7 deg visual angle was presented in a static surround either with continuous-flash suppression in the dominant eye (CFS condition to make the surround inperceptible or without the suppression (no-CFS condition. The surround stimulus was either a Mondrian or a uniform field of the same mean chromaticity. Stimuli were simulated OSA color chips under red, white (D65, or green illuminant color and were presented on a CRT display. Unique yellows were measured by asking the subjects to judge whether the test stimulus appeared reddish or greenish. Two sizes of the surround stimuli (widths of 1 deg and 4 deg were used. Results showed significant shifts in unique yellow even under the CFS conditions, except for the 1 deg uniform-surround condition. Under the no-CFS condition, the shifts showed remarkable difference between subjects, except for the 4 deg Mondrian-surround condition. Interestingly, trends of the shifts showed high consistency within each subject, across conditions. These results indicate that mechanisms at both higher and lower levels than the neuronal site of interocular suppression are involved, and that the color shifts follow each subject's strategy in the higher-order mechanisms when only insufficient clues are available in the surround to estimate illuminant color.

  20. Binocular Therapy for Childhood Amblyopia Improves Vision Without Breaking Interocular Suppression.

    Science.gov (United States)

    Bossi, Manuela; Tailor, Vijay K; Anderson, Elaine J; Bex, Peter J; Greenwood, John A; Dahlmann-Noor, Annegret; Dakin, Steven C

    2017-06-01

    Amblyopia is a common developmental visual impairment characterized by a substantial difference in acuity between the two eyes. Current monocular treatments, which promote use of the affected eye by occluding or blurring the fellow eye, improve acuity, but are hindered by poor compliance. Recently developed binocular treatments can produce rapid gains in visual function, thought to be as a result of reduced interocular suppression. We set out to develop an effective home-based binocular treatment system for amblyopia that would engage high levels of compliance but that would also allow us to assess the role of suppression in children's response to binocular treatment. Balanced binocular viewing therapy (BBV) involves daily viewing of dichoptic movies (with "visibility" matched across the two eyes) and gameplay (to monitor compliance and suppression). Twenty-two children (3-11 years) with anisometropic (n = 7; group 1) and strabismic or combined mechanism amblyopia (group 2; n = 6 and 9, respectively) completed the study. Groups 1 and 2 were treated for a maximum of 8 or 24 weeks, respectively. The treatment elicited high levels of compliance (on average, 89.4% ± 24.2% of daily dose in 68.23% ± 12.2% of days on treatment) and led to a mean improvement in acuity of 0.27 logMAR (SD 0.22) for the amblyopic eye. Importantly, acuity gains were not correlated with a reduction in suppression. BBV is a binocular treatment for amblyopia that can be self-administered at home (with remote monitoring), producing rapid and substantial benefits that cannot be solely mediated by a reduction in interocular suppression.

  1. Perceptual grouping without awareness: superiority of Kanizsa triangle in breaking interocular suppression.

    Directory of Open Access Journals (Sweden)

    Lan Wang

    Full Text Available Much information could be processed unconsciously. However, there is no direct evidence on whether perceptual grouping could occur without awareness. To answer this question, we investigated whether a Kanizsa triangle (an example of perceptual grouping is processed differently from stimuli with the same local components but are ungrouped or weakly grouped. Specifically, using a suppression time paradigm we tested whether a Kanizsa triangle would emerge from interocular continuous flash suppression sooner than control stimuli. Results show a significant advantage of the Kanizsa triangle: the Kanizsa triangle emerged from suppression noise significantly faster than the control stimulus with the local Pacmen randomly rotated (t(9 = -2.78, p = 0.02; and also faster than the control stimulus with all Pacmen rotated 180° (t(11 = -3.20, p<0.01. Additional results demonstrated that the advantage of the grouped Kanizsa triangle could not be accounted for by the faster detection speed at the conscious level for the Kanizsa figures on a dynamic noise background. Our results indicate that certain properties supporting perceptual grouping could be processed in the absence of awareness.

  2. A comparison of interocular differences in patients with pigment dispersion syndrome.

    Science.gov (United States)

    Yip, Leonard W; Sothornwit, Nisa; Berkowitz, Jonathan; Mikelberg, Frederick S

    2009-01-01

    Pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) are characterized by loss of iris pigment because of reverse pupillary block. The loss of iris pigment is manifested as transillumination defects. Differences in ocular anatomy have been found between subjects with PDS and controls. Our study aims to see if differences in interocular anatomic features are also related to differences in the quantity of transillumination defects between eyes. This is an observational case series of 30 eyes of 15 subjects with PDS/PG in at least 1 eye. Patients underwent refraction, exophthalmometry, corneal and anterior chamber analysis by Pentacam, biometry, A-scan, ultrasound biomicroscopy, and anterior segment digital photography. The Pentacam mean central radii of the posterior corneal surface (cornea back Rm), vertical central radius of curvature of the posterior corneal surface (cornea back Rv), and keratometric power deviation (influence of the posterior surface of the cornea on refractive power) were statistically different between eyes with greater pigment loss and eyes with lesser pigment loss. Eyes with greater pigment loss had a larger back radius of corneal curvature and a correspondingly numerically smaller keratometric power deviation. Other measurements of ocular anatomy were not statistically significant. A flatter curvature of the posterior corneal surface of the eye is associated with increased pigment loss in PDS and PG. The authors postulate that this could result in a difference in the biomechanical properties of the cornea, increased deformation with blinking, and a pumping action resulting in the reverse pupil block of PDS.

  3. Chemical reaction due to stronger Ramachandran interaction

    Indian Academy of Sciences (India)

    The origin of a chemical reaction between two reactant atoms is associated with the activation energy, on the assumption that, high-energy collisions between these atoms, are the ones that overcome the activation energy. Here, we show that a stronger attractive van der Waals (vdW) and electron-ion Coulomb interactions ...

  4. Binocular contrast discrimination needs monocular multiplicative noise

    Science.gov (United States)

    Ding, Jian; Levi, Dennis M.

    2016-01-01

    The effects of signal and noise on contrast discrimination are difficult to separate because of a singularity in the signal-detection-theory model of two-alternative forced-choice contrast discrimination (Katkov, Tsodyks, & Sagi, 2006). In this article, we show that it is possible to eliminate the singularity by combining that model with a binocular combination model to fit monocular, dichoptic, and binocular contrast discrimination. We performed three experiments using identical stimuli to measure the perceived phase, perceived contrast, and contrast discrimination of a cyclopean sine wave. In the absence of a fixation point, we found a binocular advantage in contrast discrimination both at low contrasts (discrimination mechanisms: a nonlinear contrast transducer and multiplicative noise (MN). A binocular combination model (the DSKL model; Ding, Klein, & Levi, 2013b) was first fitted to both the perceived-phase and the perceived-contrast data sets, then combined with either the nonlinear contrast transducer or the MN mechanism to fit the contrast-discrimination data. We found that the best model combined the DSKL model with early MN. Model simulations showed that, after going through interocular suppression, the uncorrelated noise in the two eyes became anticorrelated, resulting in less binocular noise and therefore a binocular advantage in the discrimination task. Combining a nonlinear contrast transducer or MN with a binocular combination model (DSKL) provides a powerful method for evaluating the two putative contrast-discrimination mechanisms. PMID:26982370

  5. Binocular contrast-gain control for natural scenes: Image structure and phase alignment.

    Science.gov (United States)

    Huang, Pi-Chun; Dai, Yu-Ming

    2018-05-01

    In the context of natural scenes, we applied the pattern-masking paradigm to investigate how image structure and phase alignment affect contrast-gain control in binocular vision. We measured the discrimination thresholds of bandpass-filtered natural-scene images (targets) under various types of pedestals. Our first experiment had four pedestal types: bandpass-filtered pedestals, unfiltered pedestals, notch-filtered pedestals (which enabled removal of the spatial frequency), and misaligned pedestals (which involved rotation of unfiltered pedestals). Our second experiment featured six types of pedestals: bandpass-filtered, unfiltered, and notch-filtered pedestals, and the corresponding phase-scrambled pedestals. The thresholds were compared for monocular, binocular, and dichoptic viewing configurations. The bandpass-filtered pedestal and unfiltered pedestals showed classic dipper shapes; the dipper shapes of the notch-filtered, misaligned, and phase-scrambled pedestals were weak. We adopted a two-stage binocular contrast-gain control model to describe our results. We deduced that the phase-alignment information influenced the contrast-gain control mechanism before the binocular summation stage and that the phase-alignment information and structural misalignment information caused relatively strong divisive inhibition in the monocular and interocular suppression stages. When the pedestals were phase-scrambled, the elimination of the interocular suppression processing was the most convincing explanation of the results. Thus, our results indicated that both phase-alignment information and similar image structures cause strong interocular suppression. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. LHC Season 2: A stronger machine

    CERN Multimedia

    Dominguez, Daniel

    2015-01-01

    1) New magnets / De nouveaux aimants 2) Stronger connections / Des jonctions électriques renforcées 3) Safer magnets / Des aimants plus sûrs 4) Higher energy beams / Des faisceaux d’énergie plus élevée 5) Narrower beams / Des faisceaux plus serrés 6) Smaller but closer proton packets / Des groupes de protons plus petits mais plus rapprochés 7) Higher voltage / Une tension plus haute 8) Superior cryogenics / Un système cryogénique amélioré 9) Radiation-resistant electronics / Une électronique qui résiste aux radiations 10) More secure vacuum / Un vide plus sûr

  7. Gas Marbles: Much Stronger than Liquid Marbles

    Science.gov (United States)

    Timounay, Yousra; Pitois, Olivier; Rouyer, Florence

    2017-06-01

    Enwrapping liquid droplets with hydrophobic particles allows the manufacture of so-called "liquid marbles" [Aussillous and Quéré Nature (London) 411, 924 (2001); , 10.1038/35082026Mahadevan Nature (London)411, 895 (2001), 10.1038/35082164]. The recent intensive research devoted to liquid marbles is justified by their very unusual physical and chemical properties and by their potential for various applications, from microreactors to water storage, including water pollution sensors [Bormashenko Curr. Opin. Colloid Interface Sci. 16, 266 (2011), 10.1016/j.cocis.2010.12.002]. Here we demonstrate that this concept can be successfully applied for encapsulating and protecting small gas pockets within an air environment. Similarly to their liquid counterparts, those new soft-matter objects, that we call "gas marbles," can sustain external forces. We show that gas marbles are surprisingly tenfold stronger than liquid marbles and, more importantly, they can sustain both positive and negative pressure differences. This magnified strength is shown to originate from the strong cohesive nature of the shell. Those interesting properties could be exploited for imprisoning valuable or polluted gases or for designing new aerated materials.

  8. More superimposition for contrast-modulated than luminance-modulated stimuli during binocular rivalry.

    Science.gov (United States)

    Skerswetat, Jan; Formankiewicz, Monika A; Waugh, Sarah J

    2018-01-01

    Luminance-modulated noise (LM) and contrast-modulated noise (CM) gratings were presented with interocularly correlated, uncorrelated and anti-correlated binary noise to investigate their contributions to mixed percepts, specifically piecemeal and superimposition, during binocular rivalry. Stimuli were sine-wave gratings of 2 c/deg presented within 2 deg circular apertures. The LM stimulus contrast was 0.1 and the CM stimulus modulation depth was 1.0, equating to approximately 5 and 7 times detection threshold, respectively. Twelve 45 s trials, per noise configuration, were carried out. Fifteen participants with normal vision indicated via button presses whether an exclusive, piecemeal or superimposed percept was seen. For all noise conditions LM stimuli generated more exclusive visibility, and lower proportions of superimposition. CM stimuli led to greater proportions and longer periods of superimposition. For both stimulus types, correlated interocular noise generated more superimposition than did anti- or uncorrelated interocular noise. No significant effect of stimulus type (LM vs CM) or noise configuration (correlated, uncorrelated, anti-correlated) on piecemeal perception was found. Exclusive visibility was greater in proportion, and perceptual changes more numerous, during binocular rivalry for CM stimuli when interocular noise was not correlated. This suggests that mutual inhibition, initiated by non-correlated noise CM gratings, occurs between neurons processing luminance noise (first-order component), as well as those processing gratings (second-order component). Therefore, first- and second-order components can contribute to overall binocular rivalry responses. We suggest the addition of a new well to the current energy landscape model for binocular rivalry that takes superimposition into account. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. States agree on stronger physical protection regime

    International Nuclear Information System (INIS)

    2005-01-01

    Full text: Delegates from 89 countries agreed on 8 July to fundamental changes that will substantially strengthen the Convention on the Physical Protection of Nuclear Material (CPPNM). IAEA Director General Mohamed ElBaradei welcomed the agreement in saying 'This new and stronger treaty is an important step towards greater nuclear security by combating, preventing, and ultimately punishing those who would engage in nuclear theft, sabotage or even terrorism. It demonstrates that there is indeed a global commitment to remedy weaknesses in our nuclear security regime.' The amended CPPNM makes it legally binding for States Parties to protect nuclear facilities and material in peaceful domestic use, storage as well as transport. It will also provide for expanded cooperation between and among States regarding rapid measures to locate and recover stolen or smuggled nuclear material, mitigate any radiological consequences of sabotage, and prevent and combat related offences. The original CPPNM applied only to nuclear material in international transport. Conference President Dr. Alec Baer said 'All 89 delegations demonstrated real unity of purpose. They put aside some very genuine national concerns in favour of the global interest and the result is a much improved convention that is better suited to addressing the nuclear security challenges we currently face.' The new rules will come into effect once they have been ratified by two-thirds of the 112 States Parties of the Convention, expected to take several years. 'But concrete actions are already taking place around the world. For more than 3 years, the IAEA has been implementing a systematic Nuclear Security plan, including physical protection activities designed to prevent, detect and respond to malicious acts,' said Anita Nillson, Director of the IAEA's Office of Nuclear Security. The Agency's Nuclear Security Fund, set up after the events of 9/11, has delivered $19.5 million in practical assistance to 121 countries

  10. Interocular symmetry of retinal nerve fiber layer and optic nerve head parameters measured by Cirrus high-definition optical coherence tomography in a normal pediatric population.

    Science.gov (United States)

    Pawar, Neelam; Maheshwari, Devendra; Ravindran, Meenakshi; Ramakrishnan, Renagappa

    2017-10-01

    To determine interocular differences in the retinal nerve fiber layer (RNFL) and optic nerve head (ONH) parameters in a pediatric population using Cirrus high-definition optical coherence tomography (HD-OCT). Seventy normal Indian children aged 5-17 years presenting to the Pediatric Clinic were included in this observational cross-sectional study. All subjects underwent a comprehensive ophthalmologic examination and an evaluation of the RNFL and ONH by Cirrus HD-OCT. Differences between the right and left eyes were calculated and values were compared by means of a paired t-test. Subjects were also divided into two groups based on age (under or over 10 years of age). Interocular differences in RNFL and ONH parameters together with sex and age variations for these differences were determined. The mean age of studied pediatric population was 11.83 ± 3.3 years (range 5-17). Average RNFL thickness was 94.46 ± 8.7 μm (± SD) (range 77-111). Differences in the average RNFL between right and left eyes were not statistically significant (P = 0.060). Superior quadrant RNFL was thicker in the left eye and temporal quadrant was thicker in the right eye. Among ONH parameters, there were no statistically significant differences in any parameters, except vertical cup-disc (CD) ratio which was significant (P = 0.007). The 2.5%-97.5% limits of asymmetry were 9 μm for average RNFL, 0.14 for average CD ratio, and 0.22 for vertical CD ratio. Mean interocular RNFL thickness differences in superior, superior nasal, and temporal superior quadrants were 10.61 (P sex, while only significant differences with age were observed in 12 clock hour sector analysis, mainly in nasal inferior and inferior quadrant. We report the degree of interocular symmetry of RNFL and ONH parameters measured by Cirrus HD-OCT in a healthy pediatric population. The normal interocular RNFL asymmetry should not exceed 9 μm and vertical CD ratio beyond 0.22 should be considered for further investigations. The

  11. The Educational Program "Zajedno Jaci" (Stronger Together) in Croatia

    Science.gov (United States)

    Spanja, Sanja

    2011-01-01

    In this paper, we explore intercultural learning undertaken through the educational program "Stronger Together." The program "Stronger Together" was created in 1998 in order to support and educate teachers working with children in post-war regions of Croatia using intercultural education and cooperative learning as tools for…

  12. A novel apparatus for interocular interaction evaluation in children with and without anisometropic amblyopia.

    Science.gov (United States)

    Lai, Xin Jie Angela; Alexander, Jack; He, Ming Guang; Yang, Zhi Kuan; Suttle, Catherine

    2012-07-01

    Dichoptic visual stimulation may be achieved using shutter goggles and mirror systems. These methods vary in their feasibility for use in children. This study aims to investigate the feasibility of use of a simple trial frame-based system to evaluate interactions in children. Low contrast acuity, contrast sensitivity and alignment sensitivity were measured in the non-dominant eye of 10 normally-sighted children, 14 anisometropic children without amblyopia and 14 anisometropic amblyopic children (aged 5-11 years) using goggles and a trial frame apparatus (TFA). The dominant eye was either fully or partially occluded. The difference in visual functions in the non-dominant eye between the full and partial occlusion conditions was termed the 'interaction index'. Agreement between the TFA and goggles in terms of visual functions and interactions was assessed in anisometropic children with and without amblyopia using the Bland-Altman method and t-test. Training sessions allowed subjects to become accustomed to the systems and tasks. The duration of training, the number of breaks requested by subjects and their willingness to attend further experiments were recorded in 10 subjects from each group and were compared between groups and between systems. Both Bland-Altman and t-test methods indicated acceptable agreement between the TFA and goggles in visual function and interaction measures (p > 0.05), except for contrast sensitivity measured in anisometropic children without amblyopia (p = 0.042). For all subject groups, contrast sensitivity training was significantly longer using goggles than using the TFA (p ≤ 0.001). Significantly more breaks were requested in acuity and contrast sensitivity testing, when goggles were used than when the TFA was used (p amblyopia showed a significantly greater willingness to attend more experiments using the TFA than using goggles (p = 0.025). The TFA may be a useful tool in studies of interactions in amblyopes, particularly in studies

  13. Stronger Schrödinger-like uncertainty relations

    International Nuclear Information System (INIS)

    Song, Qiu-Cheng; Qiao, Cong-Feng

    2016-01-01

    Highlights: • A stronger Schrödinger-like uncertainty relation in the sum of variances of two observables is obtained. • An improved Schrödinger-like uncertainty relation in the product of variances of two observables is obtained. • A stronger uncertainty relation in the sum of variances of three observables is proposed. - Abstract: Uncertainty relation is one of the fundamental building blocks of quantum theory. Nevertheless, the traditional uncertainty relations do not fully capture the concept of incompatible observables. Here we present a stronger Schrödinger-like uncertainty relation, which is stronger than the relation recently derived by Maccone and Pati (2014) [11]. Furthermore, we give an additive uncertainty relation which holds for three incompatible observables, which is stronger than the relation newly obtained by Kechrimparis and Weigert (2014) [12] and the simple extension of the Schrödinger uncertainty relation.

  14. Contributing factors to VEP grating acuity deficit and inter-ocular acuity difference in children with cerebral visual impairment.

    Science.gov (United States)

    Cavascan, Nívea Nunes; Salomão, Solange Rios; Sacai, Paula Yuri; Pereira, Josenilson Martins; Rocha, Daniel Martins; Berezovsky, Adriana

    2014-04-01

    To investigate contributing factors to visual evoked potential (VEP) grating acuity deficit (GAD) and inter-ocular acuity difference (IAD) measured by sweep-VEPs in children with cerebral visual impairment (CVI). VEP GAD was calculated for the better acuity eye by subtracting acuity thresholds from mean normal VEP grating acuity according to norms from our own laboratory. Deficits were categorized as mild (0.17 ≤ deficit children (66 males-57 %) with ages ranging from 1.2 to 166.5 months (median = 17.7) was examined. VEP GAD ranged from 0.17 to 1.28 log units (mean = 0.68 ± 0.27; median = 0.71), and it was mild in 23 (20 %) children, moderate in 32 (28 %) and severe in 60 (52 %). Severe deficit was significantly associated with older age and anti-seizure drug therapy. IAD ranged from 0 to 0.49 log units (mean = 0.06 ± 0.08; median = 0.04) and was acceptable in 96 (83 %) children. Children with strabismus and nystagmus had IAD significantly larger compared to children with orthoposition. In a large cohort of children with CVI, variable severity of VEP GAD was found, with more than half of the children with severe deficits. Older children and those under anti-seizure therapy were at higher risk for larger deficits. Strabismus and nystagmus provided larger IADs. These results should be taken into account on the clinical management of children with this leading cause of bilateral visual impairment.

  15. Women's political participation leads to stronger local economies ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-06-08

    Jun 8, 2016 ... Under changes to India's constitution, Indian women are gaining a stronger ... Legal reforms are encouraging women to contribute to economic growth ... on a panel on empowering women entrepreneurs at IDRC in Ottawa.

  16. Capturing age-related changes in functional contrast sensitivity with decreasing light levels in monocular and binocular vision.

    Science.gov (United States)

    Gillespie-Gallery, Hanna; Konstantakopoulou, Evgenia; Harlow, Jonathan A; Barbur, John L

    2013-09-09

    It is challenging to separate the effects of normal aging of the retina and visual pathways independently from optical factors, decreased retinal illuminance, and early stage disease. This study determined limits to describe the effect of light level on normal, age-related changes in monocular and binocular functional contrast sensitivity. We recruited 95 participants aged 20 to 85 years. Contrast thresholds for correct orientation discrimination of the gap in a Landolt C optotype were measured using a 4-alternative, forced-choice (4AFC) procedure at screen luminances from 34 to 0.12 cd/m(2) at the fovea and parafovea (0° and ±4°). Pupil size was measured continuously. The Health of the Retina index (HRindex) was computed to capture the loss of contrast sensitivity with decreasing light level. Participants were excluded if they exhibited performance outside the normal limits of interocular differences or HRindex values, or signs of ocular disease. Parafoveal contrast thresholds showed a steeper decline and higher correlation with age at the parafovea than the fovea. Of participants with clinical signs of ocular disease, 83% had HRindex values outside the normal limits. Binocular summation of contrast signals declined with age, independent of interocular differences. The HRindex worsens more rapidly with age at the parafovea, consistent with histologic findings of rod loss and its link to age-related degenerative disease of the retina. The HRindex and interocular differences could be used to screen for and separate the earliest stages of subclinical disease from changes caused by normal aging.

  17. Repeatability, interocular correlation and agreement of quantitative swept-source optical coherence tomography angiography macular metrics in healthy subjects.

    Science.gov (United States)

    Fang, Danqi; Tang, Fang Yao; Huang, Haifan; Cheung, Carol Y; Chen, Haoyu

    2018-05-29

    To investigate the repeatability, interocular correlation and agreement of quantitative swept-source optical coherence tomography angiography (SS-OCTA) metrics in healthy subjects. Thirty-three healthy normal subjects were enrolled. The macula was scanned four times by an SS-OCTA system using the 3 mm×3 mm mode. The superficial capillary map images were analysed using a MATLAB program. A series of parameters were measured: foveal avascular zone (FAZ) area, FAZ perimeter, FAZ circularity, parafoveal vessel density, fractal dimension and vessel diameter index (VDI). The repeatability of four scans was determined by intraclass correlation coefficient (ICC). Then the averaged results were analysed for intereye difference, correlation and agreement using paired t-test, Pearson's correlation coefficient (r), ICC and Bland-Altman plot. The repeatability assessment of the macular metrics exported high ICC values (ranged from 0.853 to 0.996). There is no statistically significant difference in the OCTA metrics between the two eyes. FAZ area (ICC=0.961, r=0.929) and FAZ perimeter (ICC=0.884, r=0.802) showed excellent binocular correlation. Fractal dimension (ICC=0.732, r=0.578) and VDI (ICC=0.707, r=0.547) showed moderate binocular correlation, while parafoveal vessel density had poor binocular correlation. Bland-Altman plots showed the range of agreement was from -0.0763 to 0.0954 mm 2 for FAZ area and from -0.0491 to 0.1136 for parafoveal vessel density. The macular metrics obtained using SS-OCTA showed excellent repeatability in healthy subjects. We showed high intereye correlation in FAZ area and perimeter, moderate correlation in fractal dimension and VDI, while vessel density had poor correlation in normal healthy subjects. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  18. A Stronger Reason for the Right to Sign Languages

    Science.gov (United States)

    Trovato, Sara

    2013-01-01

    Is the right to sign language only the right to a minority language? Holding a capability (not a disability) approach, and building on the psycholinguistic literature on sign language acquisition, I make the point that this right is of a stronger nature, since only sign languages can guarantee that each deaf child will properly develop the…

  19. Female Psychology in August Strindberg’s The Stronger

    Directory of Open Access Journals (Sweden)

    Anton Sutandio

    2017-11-01

    Full Text Available This research aimed to offer interpretations of August Strindberg’s The Stronger through the lens of female psychology. The Stronger is unique as it seemed very simple yet so intense and powerful with layers of interpretations. Written during 1888-1889, The Stronger, which only had two characters and only one speaking character, had become one of Strindberg’s shortest yet important plays during his career. The female psychology approach used in the analysis would cover the discussion of gender role, women’s self-esteem, competition for males, women’s friendships, ego style, and female psychology. It was an interdisciplinary research that combined structuralist, historical, biographical, and feminist approach to gain a better interpretation on the play. By referring to three different sources on the concept of female psychology, the analysis offered different and interesting interpretations on the nature and dynamics of the two female characters’ relationship. The Stronger has shown an enigmatic attraction in Strindberg’s authorship in which the readers could see the co-existence, collision, conflict, and merge of different paradigms concerning sex, gender, and sexuality.

  20. Women's political participation leads to stronger local economies ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Edgard Rodriguez - IDRC. Women attend a self-help group meeting near Hyderabad, India. Keenara Khanderia. Under changes to India's constitution, Indian women are gaining a stronger political voice. Legal reforms are encouraging women to contribute to economic growth and investments in community growth.

  1. Contrast Materials

    Science.gov (United States)

    ... is mixed with water before administration liquid paste tablet When iodine-based and barium-sulfate contrast materials ... for patients with kidney failure or allergies to MRI and/or computed tomography (CT) contrast material. Microbubble ...

  2. Stronger vection in junior high school children than in adults.

    Science.gov (United States)

    Shirai, Nobu; Imura, Tomoko; Tamura, Rio; Seno, Takeharu

    2014-01-01

    Previous studies have shown that even elementary school-aged children (7 and 11 years old) experience visually induced perception of illusory self-motion (vection) (Lepecq et al., 1995, Perception, 24, 435-449) and that children of a similar age (mean age = 9.2 years) experience more rapid and stronger vection than do adults (Shirai et al., 2012, Perception, 41, 1399-1402). These findings imply that although elementary school-aged children experience vection, this ability is subject to further development. To examine the subsequent development of vection, we compared junior high school students' (N = 11, mean age = 14.4 years) and adults' (N = 10, mean age = 22.2 years) experiences of vection. Junior high school students reported significantly stronger vection than did adults, suggesting that the perceptual experience of junior high school students differs from that of adults with regard to vection and that this ability undergoes gradual changes over a relatively long period of development.

  3. Contrast-balanced binocular treatment in children with deprivation amblyopia.

    Science.gov (United States)

    Hamm, Lisa M; Chen, Zidong; Li, Jinrong; Dai, Shuan; Black, Joanna; Yuan, Junpeng; Yu, Minbin; Thompson, Benjamin

    2017-11-28

    Children with deprivation amblyopia due to childhood cataract have been excluded from much of the emerging research into amblyopia treatment. An investigation was conducted to determine whether contrast-balanced binocular treatment - a strategy currently being explored for children with anisometropic and strabismic amblyopia - may be effective in children with deprivation amblyopia. An unmasked, case-series design intended to assess proof of principle was employed. Eighteen children with deprivation amblyopia due to childhood cataracts (early bilateral n = 7, early unilateral n = 7, developmental n = 4), as well as 10 children with anisometropic (n = 8) or mixed anisometropic and strabismic amblyopia (n = 2) were prescribed one hour a day of treatment over a six-week period. Supervised treatment was available. Visual acuity, contrast sensitivity, global motion perception and interocular suppression were measured pre- and post-treatment. Visual acuity improvements occurred in the anisometropic/strabismic group (0.15 ± 0.05 logMAR, p = 0.014), but contrast sensitivity did not change. As a group, children with deprivation amblyopia had a smaller but statistically significant improvement in weaker eye visual acuity (0.09 ± 0.03 logMAR, p = 0.004), as well a significant improvement in weaker eye contrast sensitivity (p = 0.004). Subgroup analysis suggested that the children with early bilateral deprivation had the largest improvements, while children with early unilateral cataract did not improve. Interestingly, binocular contrast sensitivity also improved in children with early bilateral deprivation. Global motion perception improved for both subgroups with early visual deprivation, as well as children with anisometropic or mixed anisometropic/strabismic amblyopia. Interocular suppression improved for all subgroups except children with early unilateral deprivation. These data suggest that supervised contrast-balanced binocular

  4. Stronger interference from distractors in the right hemifield during visual search.

    Science.gov (United States)

    Carlei, Christophe; Kerzel, Dirk

    2018-03-01

    The orientation-bias hypothesis states that there is a bias to attend to the right visual hemifield (RVF) when there is spatial competition between stimuli in the left and right hemifield [Pollmann, S. (1996). A pop-out induced extinction-like phenomenon in neurologically intact subjects. Neuropsychologia, 34(5), 413-425. doi: 10.1016/0028-3932(95)00125-5 ]. In support of this hypothesis, stronger interference was reported for RVF distractors with contralateral targets. In contrast, previous studies using rapid serial visual presentation (RSVP) found stronger interference from distractors in the left visual hemifield (LVF). We used the additional singleton paradigm to test whether this discrepancy was due to the different distractor features that were employed (colour vs. orientation). Interference from the colour distractor with contralateral targets was larger in the RVF than in the LVF. However, the asymmetrical interference disappeared when observers had to search for an inconspicuous colour target instead of the inconspicuous shape target. We suggest that the LVF orienting-bias is limited to situations where search is driven by bottom-up saliency (singleton search) instead of top-down search goals (feature search). In contrast, analysis of the literature suggests the opposite for the LVF bias in RSVP tasks. Thus, the attentional asymmetry may depend on whether the task involves temporal or spatial competition, and whether search is based on bottom-up or top-down signals.

  5. Stronger misdirection in curved than in straight motion

    Directory of Open Access Journals (Sweden)

    Jorge eOtero-Millan

    2011-11-01

    Full Text Available Illusions developed by magicians are a rich and largely untapped source of insight into perception and cognition. Here we show that curved motion, as employed by the magician in a classic sleight of hand trick, generates stronger misdirection than rectilinear motion, and that this difference can be explained by the differential engagement of the smooth pursuit and the saccadic oculomotor systems. This research moreover exemplifies how the magician’s intuitive understanding of the spectator’s mindset can surpass that of the cognitive scientist in specific instances, and that observation-based behavioral insights developed by magicians are worthy of quantitative investigation in the neuroscience laboratory.

  6. The right of the stronger: The play Sisyphus and critias

    Directory of Open Access Journals (Sweden)

    Jordović Ivan

    2004-01-01

    Full Text Available The Focus of this study is the standpoint of the play Sisyphus and critias the leader of the thirty towards the right of the stronger. this is a question of constant interest in scientific circles, since its answer can serve as the indicator of the influence this famous theory has had. this interest has been encouraged by the fact that critias’ authorship of the play is questionable. however, the question of the author is not of primary importance for this article, because there are some arguments, among some well known ones, which were not considered and which Show that in this satire, regardless of the author and the purpose of this fragment, the right of the stronger is actually non-existant. the first argument to support this theory is that nomosphysis antithesis is nowhere explicitly mentioned although it is the crucial element of the right of the stronger. in addition there is no claim in the play that the exploitation of the strong by the week or by law accrued. the second argument is that despite the incapability of laws to prevent the secret injustice, they and their importance for the human society are depicted in a positive light. it should also be noted that, unlike callicles and glaucon, laws are created to stop the bad and not the good. the third argument is that the invention of religion is accepted as a positive achievement, which finally enables the overcoming of primeval times and lawlessness. the reflection of this argument is a positive characterization of the individual who invented the fear of gods. the fourth argument, which has not been taken into consideration so far is the way the supporters and opponents of lawlessness are described and marked as κακοί and έσξλοί in the satire only physically strong are considered as strong as opposed to callicles, where they are also spiritually superior. intelectually superior in Sisyphus is the inventor of the fear of gods who is also in favor of law and order. the fact

  7. Stronger multilayer acrylic dielectric elastomer actuators with silicone gel coatings

    Science.gov (United States)

    Lau, Gih-Keong; La, Thanh-Giang; Sheng-Wei Foong, Ervin; Shrestha, Milan

    2016-12-01

    Multilayer dielectric elastomer actuators (DEA) perform worst off than single-layer DEAs due to higher susceptibility to electro-thermal breakdown. This paper presents a hot-spot model to predict the electro-thermal breakdown field of DEAs and its dependence on thermal insulation. To inhibit the electrothermal breakdown, silicone gel coating was applied as barrier coating to multilayer acrylic DEA. The gel coating helps suppress the electro-thermally induced puncturing of DEA membrane at the hot spot. As a result, the gel-coated DEAs, in either a single layer or a multilayer stack, can produce 30% more isometric stress change as compared to those none-coated. These gel-coated acrylic DEAs show great potential to make stronger artificial muscles.

  8. Contrast media

    International Nuclear Information System (INIS)

    Decazes, Ph.

    2004-01-01

    The Guerbet firm, which holds 69% of the capital on the contrast media for medical imagery, could sale about 20% of this capital in order to accelerate its development in the United States, one of its next market with the Japan. (O.M.)

  9. Conservatives Anticipate and Experience Stronger Emotional Reactions to Negative Outcomes.

    Science.gov (United States)

    Joel, Samantha; Burton, Caitlin M; Plaks, Jason E

    2014-02-01

    The present work examined whether conservatives and liberals differ in their anticipation of their own emotional reactions to negative events. In two studies, participants imagined experiencing positive or negative outcomes in domains that do not directly concern politics. In Study 1, 190 American participants recruited online (64 male, Mage  = 32 years) anticipated their emotional responses to romantic relationship outcomes. In Study 2, 97 Canadian undergraduate students (26 male, Mage  = 21 years) reported on their anticipated and experienced emotional responses to academic outcomes. In both studies, more conservative participants predicted they would feel stronger negative emotions following negative outcomes than did more liberal participants. Furthermore, a longitudinal follow-up of Study 2 participants revealed that more conservative participants actually felt worse than more liberal participants after receiving a lower-than-desired exam grade. These effects remained even when controlling for the Big Five traits, prevention focus, and attachment style (Study 1), and optimism (Study 2). We discuss how the relationship between political orientation and anticipated affect likely contributes to differences between conservatives and liberals in styles of decision and policy choices. © 2013 Wiley Periodicals, Inc.

  10. Enforcement costs: some humanitarian alternatives to stronger patent rights.

    Science.gov (United States)

    Trotter, Andrew

    2012-01-01

    Diseases that cause comparatively few problems in developed countries kill millions of people in the Third World each year. In many cases, people die because they cannot afford the medication needed to save their lives. In others, there are simply no drugs available because there are no wealthy western patients to justify pharmaceutical companies investing in a cure. This reveals a deep-seated problem within the patent system and the pharmaceutical industry that emphasises markets and profits at the expense of health and global welfare. Global efforts have seen substantial improvements in access to medicines in isolated areas, but with international agreements driving towards stronger patent protection and the expiry date for the TRIPS grace period fast approaching, it is time to consider alternatives which will allow the patent system to work for the humanitarian cause rather than against it. This paper considers two such problems in the patent system and pharmaceutical industry - prohibitive pricing and misdirected incentives - to offer a mode of regulation and enforcement that will support both a viable pharmaceutical industry and the human right to health and medication.

  11. Interocular differences in visual quality due to ocular aberrations and scattering in a patient with post-traumatic anisocoria: A case report

    Directory of Open Access Journals (Sweden)

    Andrés Gené-Sampedro

    2012-04-01

    Full Text Available A 41-year-old patient with visual disturbances after an ocular trauma in right eye three years before was carefully analyzed and discussed. No corneal or intraocular sequelae were present. Only a significant anisocoria could be observed. Right eye (RE achieved a best spectacle-corrected visual acuity (BSCVA of 0.05 LogMAR with a refraction of +0.50 sphere and −1.25 cylinder. Left eye (LE achieved a BSCVA of 0.0 LogMAR with a refraction of +0.75 sphere and −1.00 cylinder. In photopic conditions pupil diameter was 4.96 mm for RE and 3.02 mm for LE whereas in scotopic conditions, these values were 7.45 mm and 6.71 mm, respectively. More significant levels of higher-order corneal and ocular aberrations were found in RE for the same pupil size. In addition, the scattering index (OSI was 3.8 in RE and 1.0 in LE (4-mm pupil. In conclusion, anisocoria can lead to relevant visual disturbances if significant interocular differences in ocular aberrations and scattering are present.

  12. Interocular Shift of Visual Attention Enhances Stereopsis and Visual Acuities of Anisometropic Amblyopes beyond the Critical Period of Visual Development: A Novel Approach

    Directory of Open Access Journals (Sweden)

    Liwen Huang

    2014-01-01

    Full Text Available Aims. Increasing evidence shows that imbalanced suppressive drive prior to binocular combination may be the key factor in amblyopia. We described a novel binocular approach, interocular shift of visual attention (ISVA, for treatment of amblyopia in adult patients. Methods. Visual stimuli were presented anaglyphically on a computer screen. A square target resembling Landolt C had 2 openings, one in red and one in cyan color. Through blue-red goggles, each eye could only see one of the two openings. The patient was required to report the location of the opening presented to the amblyopic eye. It started at an opening size of 800 sec of arc, went up and down in 160 sec of arc step, and stopped when reaching the 5th reversals. Ten patients with anisometropic amblyopia older than age 14 (average age: 26.7 were recruited and received ISVA treatment for 6 weeks, with 2 training sessions per day. Results. Both Titmus stereopsis (z=-2.809, P=0.005 and Random-dot stereopsis (z=-2.317, P=0.018 were significantly improved. Average improvement in best corrected visual acuity (BCVA was 0.74 line (t=5.842, P<0.001. Conclusions. The ISVA treatment may be effective in treating amblyopia and restoring stereoscopic function.

  13. Stronger relationship of serum apolipoprotein A-1 and B with diabetic retinopathy than traditional lipids

    Directory of Open Access Journals (Sweden)

    B S Ankit

    2017-01-01

    Full Text Available Aim: Diabetic retinopathy (DR is the most common preventable cause of blindness where early detection and treatment can be sight-saving. Search for biomarkers of the disease has been relentless. We aimed to determine whether lipoproteins apolipoproteins A1 and B1 (Apo-A1 and Apo-B1 have stronger associations with DR in contrast to conventionally measured low-density lipoprotein (LDL and high-density lipoprotein cholesterol levels. Materials and Methods: We performed a cross-sectional study and studied 117 patients. Serum lipid profile was assessed by autoanalyzer. Serum Apo-A1 and Apo-B were measured using immunoturbidimetric kit on an autoanalyzer. Apo-B/A1 ratio was calculated. Retinopathy was graded from the digital retinal photographs, taken with nonmydriatic auto fundus camera and classified according to International Clinical DR Disease Severity Scale. Results: Mean Apo-A1 for mild, moderate, severe retinopathy, and proliferative DR (PDR shows a significant negative correlation (P = 0.001 with severity of retinopathy. Mean Apo-B for mild, moderate, severe, PDR displayed a significant positive correlation with severity of retinopathy (P = 0.001. Mean Apo-B/A1 for mild, moderate, severe, PDR showed highly significant positive correlation with severity of retinopathy (P < 0.001. In contrast, mean LDL for mild, moderate, severe, PDR showed insignificant association with severity of DR (P = 0.081. Conclusion: Apo-A1 and Apo-B have a stronger association with the development of DR than traditional lipids and can thus facilitate early detection and treatment of the disease.

  14. Cheetahs have a stronger constitutive innate immunity than leopards.

    Science.gov (United States)

    Heinrich, Sonja K; Hofer, Heribert; Courtiol, Alexandre; Melzheimer, Jörg; Dehnhard, Martin; Czirják, Gábor Á; Wachter, Bettina

    2017-03-23

    As a textbook case for the importance of genetics in conservation, absence of genetic variability at the major histocompatibility complex (MHC) is thought to endanger species viability, since it is considered crucial for pathogen resistance. An alternative view of the immune system inspired by life history theory posits that a strong response should evolve in other components of the immune system if there is little variation in the MHC. In contrast to the leopard (Panthera pardus), the cheetah (Acinonyx jubatus) has a relatively low genetic variability at the MHC, yet free-ranging cheetahs are healthy. By comparing the functional competence of the humoral immune system of both species in sympatric populations in Namibia, we demonstrate that cheetahs have a higher constitutive innate but lower induced innate and adaptive immunity than leopards. We conclude (1) immunocompetence of cheetahs is higher than previously thought; (2) studying both innate and adaptive components of immune systems will enrich conservation science.

  15. One Year After Fukushima, Nuclear Safety Is Stronger

    International Nuclear Information System (INIS)

    2012-01-01

    Full text: Nuclear power is safer than it was a year ago as the nuclear industry, regulators and governments act on the lessons of Fukushima, but that safety must never be taken for granted, said Yukiya Amano, Director General of the International Atomic Energy Agency (IAEA). Speaking ahead of the first anniversary of the Fukushima Daiichi nuclear accident on 11 March, Amano said a culture of constant vigilance and improvement was vital to ensure that the benefits of nuclear power could be harnessed as safely as humanly possible. 'Nuclear safety is stronger than it was a year ago', he said. 'Fukushima Daiichi was a very serious accident, but we know what went wrong and we have a clear course of action to tackle those causes - not only in Japan, but anywhere in the world. 'Now we have to keep up the momentum. Complacency can kill'. On 11 March 2011 a huge earthquake and tsunami left more than 20 000 people dead or missing in eastern Japan. Amidst widespread destruction, the tsunami slammed into the Fukushima Daiichi Nuclear Power Station, disabling cooling systems and leading to fuel meltdowns in three of the six Units. The accident was a jolt to the nuclear industry, regulators and governments. It was triggered by a massive force of nature, but it was existing weaknesses of design regarding defence against natural hazards, regulatory oversight, accident management and emergency response that allowed it to unfold as it did. For example: The nuclear regulator was not sufficiently independent, allowing weak oversight of the operator, TEPCO, and regulatory requirements fell short of international best practice; Not enough attention was paid to guarding against possible extreme events at the Fukushima Daiichi site, leaving critical safety functions such as cooling systems vulnerable to the tsunami; Training to respond to serious accidents was inadequate, as were mitigation measures to prevent hydrogen explosions and protect the venting system; and Accident command lines

  16. Faster, Stronger, Healthier: Adolescent-Stated Reasons for Dietary Supplementation.

    Science.gov (United States)

    Zdešar Kotnik, Katja; Jurak, Gregor; Starc, Gregor; Golja, Petra

    Examine the underlying reasons and sources of recommendation for dietary supplement (DS) use among adolescents. Cross-sectional analysis of children's development in Slovenia in September to October, 2014. Nationally recruited sample. Adolescents aged 14-19 years enrolled in 15 high schools (n = 1,463). Reasons for and sources of recommendation for DS use, sports club membership, sports discipline, and extent of physical activity (PA) were self-reported data. Chi-square test of independence was performed to compare the prevalence of DS use between groups with different extents of PA and nonathletes/athletes, referring to 11 different reasons and 9 different sources of recommendation for DS use. Use of DS was widespread among adolescents (69%), athletes (76%), and nonathletes (66%). Higher prevalence of supplementation was observed in males, who justified it use for sports performance enhancement and better development and function of muscles. In contrast, females emphasized immune system improvement. Higher extent of PA was associated with a higher prevalence of DS use. This was especially evident in males, who participated in team sports. A high percentage of adolescents (41%) decided on their own to use DS and because of advice from parents or relatives (30%). Several reasons for the widespread use of DS in adolescents were associated with sports participation. Therefore, educational programs regarding DS use should be targeted primarily to adolescents and their parents who are involved in sports, and especially team sports. Copyright © 2017 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

  17. Age differences in autobiographical memory across the adult lifespan: older adults report stronger phenomenology.

    Science.gov (United States)

    Luchetti, Martina; Sutin, Angelina R

    2018-01-01

    As an individual's life story evolves across adulthood, the subjective experience (phenomenology) of autobiographical memory likely changes. In addition to age at retrieval, both the recency of the memory and the age when a memory is formed may be particularly important to its phenomenology. The present work examines the effect of three temporal factors on phenomenology ratings: (a) age of the participant, (b) age at the event reported in the memory, and (c) memory age (recency). A large sample of Americans (N = 1120), stratified by chronological age, recalled and rated two meaningful memories, a Turning Point and an Early Childhood Memory. Ratings of phenomenology (e.g., vividness of turning points) were higher among older adults compared to younger adults. Memories of events from the reminiscence bump were more positive in valence than events from other time periods but did not differ on other phenomenological dimensions; recent memories had stronger phenomenology than remote memories. In contrast to phenomenology, narrative content was generally unrelated to participant age, age at the event, or memory age. Overall, the findings indicate age-related differences in how meaningful memories are re-experienced.

  18. Development of contrast media

    International Nuclear Information System (INIS)

    Krause, W.

    1993-01-01

    Description of all contrast media (ionic and nonionic monomers, ionic and nonionic dimers) was presented. Chemotoxicity, osmolality and viscosity of some contrast agents were analyzed. The main adverse reactions to ionic and nonionic contrast media were described

  19. Radiographic contrast media

    International Nuclear Information System (INIS)

    Golman, K.; Holtz, E.; Almen, T.

    1987-01-01

    Contrast media are used in diagnostic radiology to enhance the X-ray attenuation between a body structure of interest and the surrounding tissue. A detail becomes perceptible on a roentgenogram only when its contrast exceeds a minimum value in relation to the background. Small areas of interest must have higher contrast than the background. The contrast effect depends on concentration of the contrast media with the body. A high contrast media concentration difference thus gives rise to more morphological details in the radiographs. Contrast media can be divided into negative contrast media such as air and gas which attenuate X-rays less than the body tissues, and positive contrast materials which attenuate X-rays more than the body tissues. The positive contrast media all contain either iodine (atomic number 53) or barium (atomic number 56) and can be divided into water-insoluble and water-soluble contrast media

  20. Lower-Body Muscle Structure and Jump Performance of Stronger and Weaker Surfing Athletes.

    Science.gov (United States)

    Secomb, Josh L; Nimphius, Sophia; Farley, Oliver R; Lundgren, Lina; Tran, Tai T; Sheppard, Jeremy M

    2016-07-01

    To identify whether there are any significant differences in the lower-body muscle structure and countermovement-jump (CMJ) and squat-jump (SJ) performance between stronger and weaker surfing athletes. Twenty elite male surfers had their lower-body muscle structure assessed with ultrasonography and completed a series of lower-body strength and jump tests including isometric midthigh pull (IMTP), CMJ, and SJ. Athletes were separated into stronger (n = 10) and weaker (n = 10) groups based on IMTP performance. Large significant differences were identified between the groups for vastus lateralis (VL) thickness (P = .02, ES = 1.22) and lateral gastrocnemius (LG) pennation angle (P = .01, ES = 1.20), and a large nonsignificant difference was identified in LG thickness (P = .08, ES = 0.89). Furthermore, significant differences were present between the groups for peak force, relative peak force, and jump height in the CMJ and SJ (P Stronger surfing athletes in this study had greater VL and LG thickness and LG pennation angle. These muscle structures may explain their better performance in the CMJ and SJ. A unique finding in this study was that the stronger group appeared to better use their strength and muscle structure for braking as they had significantly higher eccentric peak velocity and vertical displacement during the CMJ. This enhanced eccentric phase may have resulted in a greater production and subsequent utilization of stored elastic strain energy that led to the significantly better CMJ performance in the stronger group.

  1. A stronger patch test elicitation reaction to the allergen hydroxycitronellal plus the irritant sodium lauryl sulfate

    DEFF Research Database (Denmark)

    Heydorn, S; Andersen, K E; Johansen, J D

    2003-01-01

    Household and cleaning products often contain both allergens and irritants. The aim of this double-blinded, randomized, paired study was to determine whether patch testing with an allergen (hydroxycitronellal) combined with an irritant [sodium lauryl sulfate (SLS)] cause a stronger patch test...

  2. Predatory blue crabs induce stronger nonconsumptive effects in eastern oysters Crassostrea virginica than scavenging blue crabs

    Directory of Open Access Journals (Sweden)

    Avery E. Scherer

    2017-02-01

    Full Text Available By influencing critical prey traits such as foraging or habitat selection, predators can affect entire ecosystems, but the nature of cues that trigger prey reactions to predators are not well understood. Predators may scavenge to supplement their energetic needs and scavenging frequency may vary among individuals within a species due to preferences and prey availability. Yet prey reactions to consumers that are primarily scavengers versus those that are active foragers have not been investigated, even though variation in prey reactions to scavengers or predators might influence cascading nonconsumptive effects in food webs. Oysters Crassostrea virginica react to crab predators by growing stronger shells. We exposed oysters to exudates from crabs fed live oysters or fed aged oyster tissue to simulate scavenging, and to controls without crab cues. Oysters grew stronger shells when exposed to either crab exudate, but their shells were significantly stronger when crabs were fed live oysters. The stronger response to predators than scavengers could be due to inherent differences in diet cues representative of reduced risk in the presence of scavengers or to degradation of conspecific alarm cues in aged treatments, which may mask risk from potential predators subsisting by scavenging.

  3. Peptide-MHC class I stability is a stronger predictor of CTL immunogenicity than peptide affinity

    DEFF Research Database (Denmark)

    Harndahl, Mikkel Nors; Rasmussen, Michael; Nielsen, Morten

    2012-01-01

    Peptide-MHC class I stability is a stronger predictor of CTL immunogenicity than peptide affinity Mikkel Harndahla, Michael Rasmussena, Morten Nielsenb, Soren Buusa,∗ a Laboratory of Experimental Immunology, Faculty of Health Sciences, University of Copenhagen, Denmark b Center for Biological Seq...... al., 2007. J. Immunol. 178, 7890–7901. doi:10.1016/j.molimm.2012.02.025...

  4. BUILDING STRONGER STATE ENERGY PARTNERSHIPS WITH THE U.S. DEPARTMENT OF ENERGY

    Energy Technology Data Exchange (ETDEWEB)

    Kate Burke

    2002-11-01

    This technical progress report includes an update of the progress during the second year of cooperative agreement DE-FC26-00NT40802, Building Stronger State Energy Partnerships with the U.S. Department of Energy. The report also describes the barriers in conduct of the effort, and our assessment of future progress and activities.

  5. Becoming Stronger at Broken Places: A Model for Group Work with Young Adult from Divorced Families.

    Science.gov (United States)

    Hage, Sally M.; Nosanow, Mia

    2000-01-01

    Describes a model for group work with young adults from divorced families using an 8-session psychoeducational group intervention. Goals include reducing isolation, establishing connectedness, and building a stronger sense of identify. By educating young adults on topics such as assertiveness, communication skills, and self-esteem, it will give…

  6. A Human Capital Framework for a Stronger Teacher Workforce. Advancing Teaching--Improving Learning. White Paper

    Science.gov (United States)

    Myung, Jeannie; Martinez, Krissia; Nordstrum, Lee

    2013-01-01

    Building a stronger teacher workforce requires the thoughtful orchestration of multiple processes working together in a human capital system. This white paper presents a framework that can be used to take stock of current efforts to enhance the teacher workforce in school districts or educational organizations, as well as their underlying theories…

  7. Contrast induced nephropathy

    DEFF Research Database (Denmark)

    Stacul, Fulvio; van der Molen, Aart J; Reimer, Peter

    2011-01-01

    PURPOSE: The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 1999 guidelines on contrast medium-induced nephropathy (CIN). AREAS COVERED: Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic me...

  8. Generalized phase contrast:

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast...

  9. Perforations during contrast enema

    International Nuclear Information System (INIS)

    Vogel, H.; Steinkamp, U.; Grabbe, E.; Allgemeines Krankenhaus Ochsenzoll, Hamburg

    1983-01-01

    During contrast enema, perforation into the retroperitoneal space can be differentiated from perforation into the peritoneum and perforation into the intestinal wall associated with formation of barium granulomas or submucosal spreading of the contrast medium. Other special forms are perforation with contrast medium embolism of diverticula; of the processus vermiformis; penetration of contrast medium into fistulous systems and from the operated areas. Risk factors are: balloon catheter, intestinal tubes with a hard tip, preternatural anus, excessive enema pressure, contrast medium additions, preceding manipulations, intestinal diseases, advanced age and delegation of manipulations to assistants and unskilled staff. Children are particularly at risk. (orig.) [de

  10. Contrast induced nephropathy

    DEFF Research Database (Denmark)

    Stacul, Fulvio; van der Molen, Aart J; Reimer, Peter

    2011-01-01

    PURPOSE: The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 1999 guidelines on contrast medium-induced nephropathy (CIN). AREAS COVERED: Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic me....../min/1.73 m (2) is CIN risk threshold for intravenous contrast medium. • Hydration with either saline or sodium bicarbonate reduces CIN incidence. • Patients with eGFR = 60 ml/min/1.73 m (2) receiving contrast medium can continue metformin normally....

  11. Spectral intensity dependence an isotropy of sources stronger than 0.1 Jy at 2700 MHz

    International Nuclear Information System (INIS)

    Balonek, T.J.; Broderick, J.J.; Condon, J.J.; Crawford, D.F.; Jauncey, D.L.

    1975-01-01

    The 1000-foot (305 m) telescope of the National Astronomy and Ionosphere Center was used to measure 430 MHz flux densities of sources stronger than 0.1 Jy at 2700 MHz. Distributions of the resulting two-point spectral indices α (430, 2700) of sources in the intensity range 0.1less than or equal toS<0.35 Jy were compared with α (318, 2700) distributions of sources stronger than 0.35 Jy at 2700 MHz. The median normal-component spectral index and fraction of flat-spectrum sources in the faintest sample do not continue the previously discovered trend toward increased spectral steepening of faint sources. This result differs from the prediction of simple evolutionary cosmological models and therefore favors the alternative explanation that local source-density inhomogeneities are responsible for the observed intensity dependence of spectral indices

  12. Crosstalk in concurrent repeated games impedes direct reciprocity and requires stronger levels of forgiveness.

    Science.gov (United States)

    Reiter, Johannes G; Hilbe, Christian; Rand, David G; Chatterjee, Krishnendu; Nowak, Martin A

    2018-02-07

    Direct reciprocity is a mechanism for cooperation among humans. Many of our daily interactions are repeated. We interact repeatedly with our family, friends, colleagues, members of the local and even global community. In the theory of repeated games, it is a tacit assumption that the various games that a person plays simultaneously have no effect on each other. Here we introduce a general framework that allows us to analyze "crosstalk" between a player's concurrent games. In the presence of crosstalk, the action a person experiences in one game can alter the person's decision in another. We find that crosstalk impedes the maintenance of cooperation and requires stronger levels of forgiveness. The magnitude of the effect depends on the population structure. In more densely connected social groups, crosstalk has a stronger effect. A harsh retaliator, such as Tit-for-Tat, is unable to counteract crosstalk. The crosstalk framework provides a unified interpretation of direct and upstream reciprocity in the context of repeated games.

  13. Daytime warming has stronger negative effects on soil nematodes than night-time warming

    OpenAIRE

    Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

    2017-01-01

    Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatmen...

  14. Phase contrast image synthesis

    DEFF Research Database (Denmark)

    Glückstad, J.

    1996-01-01

    A new method is presented for synthesizing arbitrary intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zernike phase contrast method into the domain of full range [0; 2 pi] phase modulation. By controlling the average value of the input phase funct...... function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished. The method presented is also directly applicable in dark field image synthesis....

  15. Dialysis and contrast media

    International Nuclear Information System (INIS)

    Morcos, Sameh K.; Thomsen, Henrik S.; Webb, Judith A.W.

    2002-01-01

    In a previous survey we revealed uncertainty among responders about (a) whether or not to perform hemodialysis in patients with severely reduced renal function who had received contrast medium; and (b) when to perform hemodialysis in patients on regular treatment with hemodialysis or continuous ambulatory dialysis who received contrast medium. Therefore, the Contrast Media Safety Committee of The European Society of Urogenital Radiology decided to review the literature and to issue guidelines. The committee performed a Medline search. Based on this, a report and guidelines were prepared. The report was discussed at the Ninth European Symposium on Urogenital Radiology in Genoa, Italy. Hemodialysis and peritoneal dialysis safely remove both iodinated and gadolinium-based contrast media. The effectiveness of hemodialysis depends on many factors including blood and dialysate flow rate, permeability of dialysis membrane, duration of hemodialysis and molecular size, protein binding, hydrophilicity, and electrical charge of the contrast medium. Generally, several hemodialysis sessions are needed to removal all contrast medium, whereas it takes 3 weeks for continuous ambulatory dialysis to remove the agent completely. There is no need to schedule the dialysis in relation to the injection of iodinated or MR contrast media or the injection of contrast agent in relation to the dialysis program. Hemodialysis does not protect poorly functioning kidneys against contrast-medium-induced nephrotoxicity. Simple guidelines are given. (orig.)

  16. How the biotin–streptavidin interaction was made even stronger: investigation via crystallography and a chimaeric tetramer

    Science.gov (United States)

    Chivers, Claire E.; Koner, Apurba L.; Lowe, Edward D.; Howarth, Mark

    2011-01-01

    The interaction between SA (streptavidin) and biotin is one of the strongest non-covalent interactions in Nature. SA is a widely used tool and a paradigm for protein–ligand interactions. We previously developed a SA mutant, termed Tr (traptavidin), possessing a 10-fold lower off-rate for biotin, with increased mechanical and thermal stability. In the present study, we determined the crystal structures of apo-Tr and biotin–Tr at 1.5 Å resolution. In apo-SA the loop (L3/4), near biotin's valeryl tail, is typically disordered and open, but closes upon biotin binding. In contrast, L3/4 was shut in both apo-Tr and biotin–Tr. The reduced flexibility of L3/4 and decreased conformational change on biotin binding provide an explanation for Tr's reduced biotin off- and on-rates. L3/4 includes Ser45, which forms a hydrogen bond to biotin consistently in Tr, but erratically in SA. Reduced breakage of the biotin–Ser45 hydrogen bond in Tr is likely to inhibit the initiating event in biotin's dissociation pathway. We generated a Tr with a single biotin-binding site rather than four, which showed a simi-larly low off-rate, demonstrating that Tr's low off-rate was governed by intrasubunit effects. Understanding the structural features of this tenacious interaction may assist the design of even stronger affinity tags and inhibitors. PMID:21241253

  17. Contrast analysis : A tutorial

    NARCIS (Netherlands)

    Haans, A.

    2018-01-01

    Contrast analysis is a relatively simple but effective statistical method for testing theoretical predictions about differences between group means against the empirical data. Despite its advantages, contrast analysis is hardly used to date, perhaps because it is not implemented in a convenient

  18. Sexual harassment and emotional and behavioural symptoms in adolescence: stronger associations among boys than girls.

    Science.gov (United States)

    Kaltiala-Heino, Riittakerttu; Fröjd, Sari; Marttunen, Mauri

    2016-08-01

    To study the associations between subjection to sexual harassment and emotional (depression) and behavioural (delinquency) symptoms among 14-to-18-year-old adolescents, and gender differences within these associations. 90,953 boys and 91,746 girls aged 14-18 participated in the School Health Promotion Study (SHPS), a school-based survey designed to examine the health, health behaviours, and school experiences of teenagers. Experiences of sexual harassment were elicited with five questions addressing five separate forms of harassment. Depression was measured by the 13-item Beck Depression Inventory and delinquency with a modified version of the International Self-Report Delinquency Study (ISRD) instrument. Data were analysed using cross-tabulations with Chi-square statistics and logistic regression. All sexual harassment experiences studied were associated with both depression (adjusted odds ratios varied from 2.2 to 2.7 in girls and from 2.0 to 5.1 in boys) and delinquency (adjusted odds ratios 3.1-5.0 in girls and 1.7-6.9 in boys). Sexual name-calling had a stronger association with depression and with delinquency in girls (adjusted odds ratios, respectively, 2.4 and 4.2), than in boys (adjusted odds ratios, respectively, 2.0 and 1.7), but otherwise stronger associations with emotional and behavioural symptoms were seen in boys. Subjection to sexual harassment is associated with both emotional and behavioural symptoms in both girls and boys. The associations are mostly stronger for boys. Boys subjected to sexual harassment may feel particularly threatened regarding their masculinity, and there may be less support available for boys traumatised due to sexual harassment.

  19. Increased fire frequency promotes stronger spatial genetic structure and natural selection at regional and local scales in Pinus halepensis Mill.

    Science.gov (United States)

    Budde, Katharina B; González-Martínez, Santiago C; Navascués, Miguel; Burgarella, Concetta; Mosca, Elena; Lorenzo, Zaida; Zabal-Aguirre, Mario; Vendramin, Giovanni G; Verdú, Miguel; Pausas, Juli G; Heuertz, Myriam

    2017-04-01

    The recurrence of wildfires is predicted to increase due to global climate change, resulting in severe impacts on biodiversity and ecosystem functioning. Recurrent fires can drive plant adaptation and reduce genetic diversity; however, the underlying population genetic processes have not been studied in detail. In this study, the neutral and adaptive evolutionary effects of contrasting fire regimes were examined in the keystone tree species Pinus halepensis Mill. (Aleppo pine), a fire-adapted conifer. The genetic diversity, demographic history and spatial genetic structure were assessed at local (within-population) and regional scales for populations exposed to different crown fire frequencies. Eight natural P. halepensis stands were sampled in the east of the Iberian Peninsula, five of them in a region exposed to frequent crown fires (HiFi) and three of them in an adjacent region with a low frequency of crown fires (LoFi). Samples were genotyped at nine neutral simple sequence repeats (SSRs) and at 251 single nucleotide polymorphisms (SNPs) from coding regions, some of them potentially important for fire adaptation. Fire regime had no effects on genetic diversity or demographic history. Three high-differentiation outlier SNPs were identified between HiFi and LoFi stands, suggesting fire-related selection at the regional scale. At the local scale, fine-scale spatial genetic structure (SGS) was overall weak as expected for a wind-pollinated and wind-dispersed tree species. HiFi stands displayed a stronger SGS than LoFi stands at SNPs, which probably reflected the simultaneous post-fire recruitment of co-dispersed related seeds. SNPs with exceptionally strong SGS, a proxy for microenvironmental selection, were only reliably identified under the HiFi regime. An increasing fire frequency as predicted due to global change can promote increased SGS with stronger family structures and alter natural selection in P. halepensis and in plants with similar life history traits

  20. Production of plastified wood with stronger static bending strength means of polymerization induced by gamma radiation

    International Nuclear Information System (INIS)

    Silva Filho, Elias

    1999-01-01

    The use of gamma radiation to obtain wood-polymer composites is one of the applications of radiation that presents the most commercial interest. The process, denominated radiopolymerization, comprises the impregnation of monomers into the completely dried wood followed by exposure to gamma radiation to induce polymerization of the impregnated monomers. I this context, the present work aimed the application of this process to seven kinds of wood existing in the brazilian forests. The considered monomer is styrene and the gamma source is Cobalt-60. The obtained wood-polystyrene composites were found to have stronger static bending strength. (author)

  1. Why is the radial flow in central pA collisions stronger than in AA?

    International Nuclear Information System (INIS)

    Kalaydzhyan, Tigran; Shuryak, Edward

    2014-01-01

    Both the transverse size and entropy density per area in central pA collisions is smaller than in central AA, and yet the radial flow is stronger. We propose an explanation to this puzzle. Using a weak attraction between strings through the σ-meson exchange, fitted to the lattice data, we find collective implosion of the “spaghetti” multi-string state. Collectivization of the sigma field of the strings is the QCD analog of the black hole formation occurring in holographic models

  2. Selection is stronger in early-versus-late stages of divergence in a Neotropical livebearing fish.

    Science.gov (United States)

    Ingley, Spencer J; Johnson, Jerald B

    2016-03-01

    How selection acts to drive trait evolution at different stages of divergence is of fundamental importance in our understanding of the origins of biodiversity. Yet, most studies have focused on a single point along an evolutionary trajectory. Here, we provide a case study evaluating the strength of divergent selection acting on life-history traits at early-versus-late stages of divergence in Brachyrhaphis fishes. We find that the difference in selection is stronger in the early-diverged population than the late-diverged population, and that trait differences acquired early are maintained over time. © 2016 The Author(s).

  3. Building Stronger State Energy Partnerships with the U.S. Department of Energy

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Kate

    2011-09-30

    This final technical report details the results of total work efforts and progress made from October 2007 – September 2011 under the National Association of State Energy Officials (NASEO) cooperative agreement DE-FC26-07NT43264, Building Stronger State Energy Partnerships with the U.S. Department of Energy. Major topical project areas in this final report include work efforts in the following areas: Energy Assurance and Critical Infrastructure, State and Regional Technical Assistance, Regional Initiative, Regional Coordination and Technical Assistance, and International Activities in China. All required deliverables have been provided to the National Energy Technology Laboratory and DOE program officials.

  4. Contrast agents for MRI

    International Nuclear Information System (INIS)

    Bonnemain, B.

    1994-01-01

    Contrast agents MRI (Magnetic Resonance Imaging) have been developed to improve the diagnostic information obtained by this technic. They mainly interact on T1 and T2 parameters and increase consequently normal to abnormal tissues contrast. The paramagnetic agents which mainly act on longitudinal relaxation rate (T1) are gadolinium complexes for which stability is the main parameter to avoid any release of free gadolinium. The superparamagnetic agents that decrease signal intensity by an effect on transversal relaxation rate (T2) are developed for liver, digestive and lymph node imaging. Many area of research are now opened for optimal use of present and future contrast agents in MRI. (author). 28 refs., 4 tabs

  5. Compressive Phase Contrast Tomography

    International Nuclear Information System (INIS)

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-01-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  6. Fathers see stronger family resemblances than non-fathers in unrelated children's faces.

    Science.gov (United States)

    Bressan, Paola; Dal Pos, Stefania

    2012-12-01

    Even after they have taken all reasonable measures to decrease the probability that their spouses cheat on them, men still face paternal uncertainty. Such uncertainty can lead to paternal disinvestment, which reduces the children's probability to survive and reproduce, and thus the reproductive success of the fathers themselves. A theoretical model shows that, other things being equal, men who feel confident that they have fathered their spouses' offspring tend to enjoy greater fitness (i.e., leave a larger number of surviving progeny) than men who do not. This implies that fathers should benefit from exaggerating paternal resemblance. We argue that the self-deceiving component of this bias could be concealed by generalizing this resemblance estimation boost to (1) family pairs other than father-child and (2) strangers. Here, we tested the prediction that fathers may see, in unrelated children's faces, stronger family resemblances than non-fathers. In Study 1, 70 men and 70 women estimated facial resemblances between children paired, at three different ages (as infants, children, and adolescents), either to themselves or to their parents. In Study 2, 70 men and 70 women guessed the true parents of the same children among a set of adults. Men who were fathers reported stronger similarities between faces than non-fathers, mothers, and non-mothers did, but were no better at identifying childrens' real parents. We suggest that, in fathers, processing of facial resemblances is biased in a manner that reflects their (adaptive) wishful thinking that fathers and children are related.

  7. Do External or Internal Technology Spillovers Have a Stronger Influence on Innovation Efficiency in China?

    Directory of Open Access Journals (Sweden)

    Xionghe Qin

    2017-09-01

    Full Text Available In this study, we bridge an important gap in the literature by comparing the extent to which external technology spillovers, as indicated by foreign direct investment (FDI, and internal technology spillovers, as indicated by university-institute-industry cooperation (UIC, influence innovation efficiency in China. We divide the innovation process into two sequential stages, namely the knowledge creation and technology commercialization stages, and employ a network data envelopment analysis approach to measure innovation efficiency at each stage. The spatial analysis of the distribution of knowledge creation efficiency and technology commercialization efficiency reveals the heterogeneity of innovation efficiency at the provincial level. Then, a panel data regression is used to analyze the effect of FDI and UIC on innovation efficiency at each stage, using data from 2009 to 2015 for 30 provinces in China. By comparing FDI with UIC, we find that FDI has a higher coefficient and stronger significance level at the knowledge creation stage, while only industry-institute linkages exhibit a stronger association with innovation efficiency at the technology commercialization stage.

  8. When surging seas meet stronger rain: Nuclear techniques in flood management

    International Nuclear Information System (INIS)

    Quevenco, Rodolfo

    2015-01-01

    Unusually high rainfall in many parts of the world is a result of climate change, scientists say. Since warmer air can hold more water, the rationale goes, increased temperatures will increase the chances of stronger rainfall events. And when surging seas combine with stronger rain, the outcome is almost certain: floods. Floods are the most frequently occurring natural disasters, and south-east Asia is particularly vulnerable. Climate change and variability are expected to bring about increased typhoon activities, rising sea levels and off-season monsoon rains in southeast Asia and other regions. These can cause devastating floods in countries like Cambodia, Laos, Pakistan, the Philippines, Thailand and Viet Nam. For the residents of these countries who have survived the ravages of major floods, the road to recovery can be long and arduous. As the flood water recedes, they have to contend with new forms of flood: floods of concern and worries as to how to rebuild their houses, their lives and their cities. Governments, too, face huge challenges in rebuilding roads, public buildings, infrastructure and natural resources destroyed or polluted by the flood.

  9. A configural dominant account of contextual cueing: Configural cues are stronger than colour cues.

    Science.gov (United States)

    Kunar, Melina A; John, Rebecca; Sweetman, Hollie

    2014-01-01

    Previous work has shown that reaction times to find a target in displays that have been repeated are faster than those for displays that have never been seen before. This learning effect, termed "contextual cueing" (CC), has been shown using contexts such as the configuration of the distractors in the display and the background colour. However, it is not clear how these two contexts interact to facilitate search. We investigated this here by comparing the strengths of these two cues when they appeared together. In Experiment 1, participants searched for a target that was cued by both colour and distractor configural cues, compared with when the target was only predicted by configural information. The results showed that the addition of a colour cue did not increase contextual cueing. In Experiment 2, participants searched for a target that was cued by both colour and distractor configuration compared with when the target was only cued by colour. The results showed that adding a predictive configural cue led to a stronger CC benefit. Experiments 3 and 4 tested the disruptive effects of removing either a learned colour cue or a learned configural cue and whether there was cue competition when colour and configural cues were presented together. Removing the configural cue was more disruptive to CC than removing colour, and configural learning was shown to overshadow the learning of colour cues. The data support a configural dominant account of CC, where configural cues act as the stronger cue in comparison to colour when they are presented together.

  10. Generalized Phase Contrast

    CERN Document Server

    Glückstad, Jesper

    2009-01-01

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than the restrictive assumptions of conventional Zernike phase contrast analysis and achieves an expanded range of validity beyond weak phase perturbations. The generalized analysis yields design criteria for tuning experimental parameters to achieve optimal performance in terms of accuracy, fidelity and light efficiency. Optimization can address practical issues, such as finding an optimal spatial filter for the chosen application, ...

  11. Mamografia Espectral de Contraste

    OpenAIRE

    Martins, Inês Santiago; Pereira, Inês; Pacheco, Hugo Pisco; Moutinho, Leonor

    2014-01-01

    A mamografia de contraste é uma aplicação recente possível com a mamografia digital directa, que utiliza contraste iodado endovenoso tendo como princípio a neovascularização induzida no cancro da mama, permitindo obter informação morfológica e funcional. Na mamografia espectral de contraste realiza-se uma aquisição simultânea com alta e baixa energia para cada incidência após administração de contraste iodado endovenoso. É depois feita uma imagem recombinada em que são realçadas as áreas que ...

  12. Aspiration of Barium Contrast

    OpenAIRE

    Fuentes Santos, Cristina; Steen, Bárbara

    2014-01-01

    The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient’s medical fil...

  13. Aspiration of Barium Contrast

    Directory of Open Access Journals (Sweden)

    Cristina Fuentes Santos

    2014-01-01

    Full Text Available The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient’s medical file was reviewed, images were found of a barium swallow study that the patient had undergone months earlier, and we were able to observe the exact moment of the aspiration of the contrast material. The patient had been asymptomatic since the test.

  14. Contrast media: future aspects

    International Nuclear Information System (INIS)

    Weinmann, H.J.; Platzek, J.; Schirmer, H.; Pietsch, H.; Carretero, J.; Harto, J.; Medina, J.; Riefke, B.; Martin, J.

    2005-01-01

    In spite of the dramatic development in CT, there was no major breakthrough in the iodinated contrast media development. New agents based on hybrid between MRI and CT compounds may be a new innovative alternative. This new approach may also open new indications such as radiotherapy. (orig.)

  15. Roentgen contrast medium

    International Nuclear Information System (INIS)

    Tamborski, C.

    1989-01-01

    The patent deals with a roentgen contrast medium containing a perfluorinebrominealkylether of the formula C m F 2m+1 OC n F 2n Br dispersed in water, preferentially in the presence of a non-ionic dispersing agent such as a fluorinated amidoaminoxide. 2 tabs

  16. Iodinated contrast media nephrotoxicity

    International Nuclear Information System (INIS)

    Meyrier, A.

    1994-01-01

    In the late seventies, iodinated contrast agents (ICA) were considered to be a major cause of acute iatrogenic renal failure. Over the last decade new contrast agents have been synthesized, nonionic and less hyperosmolar. The incidence of acute renal failure due to ICAs, varies from 3.7 to 70% of cases according to the series, with an average figure of 10.2%. The pathophysiology of ICA nephrotoxicity was mainly studied in laboratory animal models. Three main factors are involved in an inducing ICA-mediated decrease in glomerular filtration rate: reduction of the renal plasma flow, a direct cytotoxic effect on renal tubular cells and erythrocyte alteration leading to intra-renal sludge. Excluding dysglobulinemias with urinary excretion of immunoglobulin light chains, which represent a special case of maximum nephrotoxicity, 4 main risk factors of renal toxicity have been identified in nondiabetic subjects: previous renal failure with serum creatinine levels greater than 140 μmol per liter, extracellular dehydration, age over 60 and use of high doses of ICA and/or repeated ICA injections before serum creatinine levels return to baseline. Preventive measures for avoiding ICA nephrotoxicity are threefold: maintain or restore adequate hydration with saline infusion, stop NSAID treatment several days before ICA administration, and allow a 5 day interval before repeating contrast media injections. New, nonionic and moderately hyperosmolar contrast agents appear to be much less nephrotoxic than conventional ICAs in laboratory animals and in high-risk patients. It is advisable to select such contrast media for investigating high-risk patients. This approach was recently substantiated in well designed, randomized clinical studies which included more than 2 000 patients. (author)

  17. Regular exercisers have stronger pelvic floor muscles than nonregular exercisers at midpregnancy.

    Science.gov (United States)

    Bø, Kari; Ellstrøm Engh, Marie; Hilde, Gunvor

    2018-04-01

    Today all healthy pregnant women are encouraged to be physically active throughout pregnancy, with recommendations to participate in at least 30 minutes of aerobic activity on most days of the week in addition to performing strength training of the major muscle groups 2-3 days per week and also pelvic floor muscle training. There is, however, an ongoing debate whether general physical activity enhances or declines pelvic floor muscle function. The objectives of the study were to compare vaginal resting pressure, pelvic floor muscle strength, and endurance in regular exercisers (exercise ≥30 minutes 3 or more times per week) and nonexercisers at midpregnancy. Furthermore, another objective was to assess whether regular general exercise or pelvic floor muscle strength was associated with urinary incontinence. This was a cross-sectional study at mean gestational week 20.9 (±1.4) including 218 nulliparous pregnant women, with a mean age of 28.6 years (range, 19-40 years) and prepregnancy body mass index of 23.9 kg/m 2 (SD, 4.0). Vaginal resting pressure, pelvic floor muscle strength, and pelvic floor muscle endurance were measured by a high-precision pressure transducer connected to a vaginal balloon. The International Consultation on Incontinence Questionnaire Urinary Incontinence Short Form was used to assess urinary incontinence. Differences between groups were analyzed using an independent-sample Student t test. Linear regression analysis was conducted to adjust for prepregnancy body mass index, age, smoking during pregnancy, and regular pelvic floor muscle training during pregnancy. The significance value was set to P ≤ .05. Regular exercisers had statistically significant stronger (mean 6.4 cm H 2 O [95% confidence interval, 1.7-11.2]) and more enduring (mean 39.9 cm H 2 Osec [95% confidence interval, 42.2-75.7]) pelvic floor muscles. Only pelvic floor muscle strength remained statistically significant, when adjusting for possible confounders. Pelvic floor

  18. The Integration Role of European Defense Procurement in Achieving a More Competitive and Stronger European Defense Equipment Market

    Science.gov (United States)

    2015-06-01

    and systems, even monopolistic ) essence of the supply side of the defense market . There are only a few suppliers that can meet today’s complex...DEFENSE PROCUREMENT IN ACHIEVING A MORE COMPETITIVE AND STRONGER EUROPEAN DEFENSE EQUIPMENT MARKET by Kiril O. Angelov June 2015 Thesis Advisor...COMPETITIVE AND STRONGER EUROPEAN DEFENSE EQUIPMENT MARKET 5. FUNDING NUMBERS 6. AUTHOR(S) Kiril O. Angelov 7. PERFORMING ORGANIZATION NAME(S) AND

  19. Stronger activation of SREBP-1a by nucleus-localized HBx

    International Nuclear Information System (INIS)

    Wu, Qi; Qiao, Ling; Yang, Jian; Zhou, Yan; Liu, Qiang

    2015-01-01

    We previously showed that hepatitis B virus (HBV) X protein activates the sterol regulatory element-binding protein-1a (SREBP-1a). Here we examined the role of nuclear localization of HBx in this process. In comparison to the wild-type and cytoplasmic HBx, nuclear HBx had stronger effects on SREBP-1a and fatty acid synthase transcription activation, intracellular lipid accumulation and cell proliferation. Furthermore, nuclear HBx could activate HBV enhancer I/X promoter and was more effective on up-regulating HBV mRNA level in the context of HBV replication than the wild-type HBx, while the cytoplasmic HBx had no effect. Our results demonstrate the functional significance of the nucleus-localized HBx in regulating host lipogenic pathway and HBV replication. - Highlights: • Nuclear HBx is more effective on activating SREBP-1a and FASN transcription. • Nuclear HBx is more effective on enhancing intracellular lipid accumulation. • Nuclear HBx is more effective on enhancing cell proliferation. • Nuclear HBx up-regulates HBV enhancer I/X promoter activity. • Nuclear HBx increases HBV mRNA level in the context of HBV replication

  20. Income is a stronger predictor of mortality than education in a national sample of US adults.

    Science.gov (United States)

    Sabanayagam, Charumathi; Shankar, Anoop

    2012-03-01

    Low socioeconomic status (SES) is associated with mortality in several populations. SES measures, such as education and income, may operate through different pathways. However, the independent effect of each measure mutually adjusting for the effect of other SES measures is not clear. The association between poverty-income ratio (PIR) and education and all-cause mortality among 15,646 adults, aged >20 years, who participated in the Third National Health and Nutrition Examination Survey in the USA, was examined. The lower PIR quartiles and less than high school education were positively associated with all-cause mortality in initial models adjusting for the demographic, lifestyle and clinical risk factors. After additional adjustment for education, the lower PIR quartiles were still significantly associated with all-cause mortality. The multivariable odds ratio (OR) [95% confidence interval (CI)] of all-cause mortality comparing the lowest to the highest quartile of PIR was 2.11 (1.52-2.95, p trend education was no longer associated with all-cause mortality [multivariable OR (95% CI) of all-cause mortality comparing less than high school to more than high school education was 1.05 (0.85-1.31, p trend=0.57)]. The results suggest that income may be a stronger predictor of mortality than education, and narrowing the income differentials may reduce the health disparities.

  1. UGC galaxies stronger than 25 mJy at 4.85 GHz

    International Nuclear Information System (INIS)

    Condon, J.J.; Frayer, D.T.; Broderick, J.J.

    1991-01-01

    UGC galaxies in the declination band +5 to +75 deg were identified by position coincidence with radio sources stronger than 25 mJy on the Green Bank 4.85 GHz sky maps. Candidate identifications were confirmed or rejected with the aid of published aperture-synthesis maps and new 4.86 GHz VLA maps having 15 or 18 arcsec resolution, resulting in a sample of 347 nearby radio galaxies plus five new quasar-galaxy pairs. The radio energy sources in UGC galaxies were classified as starbursts or monsters on the basis of their infrared-radio flux ratios, infrared spectral indices, and radio morphologies. The rms scatter in the logarithmic infrared-radio ratio q is not more than 0.16 for starburst galaxies selected at 4.85 GHz. Radio spectral indices were obtained for nearly all of the UGC galaxies, and S0 galaxies account for a disproportionate share of the compact flat-spectrum (alpha less than 0.5) radio sources. The extended radio jets and lobes produced by monsters are preferentially, but not exclusively, aligned within about 30 deg of the optical minor axes of their host galaxies. The tendency toward minor-axis ejection appears to be independent of radio-source size and is strongest for elliptical galaxies. 230 refs

  2. Plant Identity Exerts Stronger Effect than Fertilization on Soil Arbuscular Mycorrhizal Fungi in a Sown Pasture.

    Science.gov (United States)

    Zheng, Yong; Chen, Liang; Luo, Cai-Yun; Zhang, Zhen-Hua; Wang, Shi-Ping; Guo, Liang-Dong

    2016-10-01

    Arbuscular mycorrhizal (AM) fungi play key roles in plant nutrition and plant productivity. AM fungal responses to either plant identity or fertilization have been investigated. However, the interactive effects of different plant species and fertilizer types on these symbiotic fungi remain poorly understood. We evaluated the effects of the factorial combinations of plant identity (grasses Avena sativa and Elymus nutans and legume Vicia sativa) and fertilization (urea and sheep manure) on AM fungi following 2-year monocultures in a sown pasture field study. AM fungal extraradical hyphal density was significantly higher in E. nutans than that in A. sativa and V. sativa in the unfertilized control and was significantly increased by urea and manure in A. sativa and by manure only in E. nutans, but not by either fertilizers in V. sativa. AM fungal spore density was not significantly affected by plant identity or fertilization. Forty-eight operational taxonomic units (OTUs) of AM fungi were obtained through 454 pyrosequencing of 18S rDNA. The OTU richness and Shannon diversity index of AM fungi were significantly higher in E. nutans than those in V. sativa and/or A. sativa, but not significantly affected by any fertilizer in all of the three plant species. AM fungal community composition was significantly structured directly by plant identity only and indirectly by both urea addition and plant identity through soil total nitrogen content. Our findings highlight that plant identity has stronger influence than fertilization on belowground AM fungal community in this converted pastureland from an alpine meadow.

  3. Exercise training raises daily activity stronger than predicted from exercise capacity in patients with COPD.

    Science.gov (United States)

    Behnke, Michaela; Wewel, Alexandra R; Kirsten, Detlef; Jörres, Rudolf A; Magnussen, Helgo

    2005-06-01

    The 6-min walking (6MWD) and 6-min treadmill distance (6MTD) are often used as measures of exercise performance in patients with COPD. The aim of our study was to assess their relationship to daily activity in the course of an exercise training program. Eighty-eight patients with stable COPD (71m/17f; mean +/- SD age, 60 +/-8 year; FEV1, 43+/-14% pred) were recruited, 66 of whom performed a hospital-based 10-day walking training, whereas 22 were treated as control. On day 16MTD, and on days 8 and 10, 6MTD and 6MWD were determined. In addition, patients used an accelerometer (TriTrac-R3D) to record 24 h-activity, whereby training sessions were excluded. In both groups there was a linear relationship (r > or = 0.84 and P daily activity did not markedly vary with exercise capacity under baseline conditions. Participation in a training program increased activity significantly stronger than predicted from the gain in exercise capacity. This underlines the importance of non-physiological, patient-centered factors associated with training in COPD.

  4. Stronger activation of SREBP-1a by nucleus-localized HBx

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qi [VIDO-InterVac, Veterinary Microbiology, University of Saskatchewan, Saskatoon (Canada); Qiao, Ling [VIDO-InterVac, University of Saskatchewan, Saskatoon, Saskatchewan (Canada); Yang, Jian [Drug Discovery Group, University of Saskatchewan, Saskatoon, Saskatchewan (Canada); Zhou, Yan [VIDO-InterVac, Veterinary Microbiology, Vaccinology and Immunotherapeutics, University of Saskatchewan, Saskatoon, Saskatchewan (Canada); Liu, Qiang, E-mail: qiang.liu@usask.ca [VIDO-InterVac, Veterinary Microbiology, Vaccinology and Immunotherapeutics, University of Saskatchewan, Saskatoon, Saskatchewan (Canada)

    2015-05-08

    We previously showed that hepatitis B virus (HBV) X protein activates the sterol regulatory element-binding protein-1a (SREBP-1a). Here we examined the role of nuclear localization of HBx in this process. In comparison to the wild-type and cytoplasmic HBx, nuclear HBx had stronger effects on SREBP-1a and fatty acid synthase transcription activation, intracellular lipid accumulation and cell proliferation. Furthermore, nuclear HBx could activate HBV enhancer I/X promoter and was more effective on up-regulating HBV mRNA level in the context of HBV replication than the wild-type HBx, while the cytoplasmic HBx had no effect. Our results demonstrate the functional significance of the nucleus-localized HBx in regulating host lipogenic pathway and HBV replication. - Highlights: • Nuclear HBx is more effective on activating SREBP-1a and FASN transcription. • Nuclear HBx is more effective on enhancing intracellular lipid accumulation. • Nuclear HBx is more effective on enhancing cell proliferation. • Nuclear HBx up-regulates HBV enhancer I/X promoter activity. • Nuclear HBx increases HBV mRNA level in the context of HBV replication.

  5. Brain Potentials Highlight Stronger Implicit Food Memory for Taste than Health and Context Associations.

    Science.gov (United States)

    Hoogeveen, Heleen R; Jolij, Jacob; Ter Horst, Gert J; Lorist, Monicque M

    2016-01-01

    Increasingly consumption of healthy foods is advised to improve population health. Reasons people give for choosing one food over another suggest that non-sensory features like health aspects are appreciated as of lower importance than taste. However, many food choices are made in the absence of the actual perception of a food's sensory properties, and therefore highly rely on previous experiences of similar consumptions stored in memory. In this study we assessed the differential strength of food associations implicitly stored in memory, using an associative priming paradigm. Participants (N = 30) were exposed to a forced-choice picture-categorization task, in which the food or non-food target images were primed with either non-sensory or sensory related words. We observed a smaller N400 amplitude at the parietal electrodes when categorizing food as compared to non-food images. While this effect was enhanced by the presentation of a food-related word prime during food trials, the primes had no effect in the non-food trials. More specifically, we found that sensory associations are stronger implicitly represented in memory as compared to non-sensory associations. Thus, this study highlights the neuronal mechanisms underlying previous observations that sensory associations are important features of food memory, and therefore a primary motive in food choice.

  6. Daytime warming has stronger negative effects on soil nematodes than night-time warming

    Science.gov (United States)

    Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

    2017-03-01

    Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

  7. Earlier adolescent substance use onset predicts stronger connectivity between reward and cognitive control brain networks.

    Science.gov (United States)

    Weissman, David G; Schriber, Roberta A; Fassbender, Catherine; Atherton, Olivia; Krafft, Cynthia; Robins, Richard W; Hastings, Paul D; Guyer, Amanda E

    2015-12-01

    Early adolescent onset of substance use is a robust predictor of future substance use disorders. We examined the relation between age of substance use initiation and resting state functional connectivity (RSFC) of the core reward processing (nucleus accumbens; NAcc) to cognitive control (prefrontal cortex; PFC) brain networks. Adolescents in a longitudinal study of Mexican-origin youth reported their substance use annually from ages 10 to 16 years. At age 16, 69 adolescents participated in a resting state functional magnetic resonance imaging scan. Seed-based correlational analyses were conducted using regions of interest in bilateral NAcc. The earlier that adolescents initiated substance use, the stronger the connectivity between bilateral NAcc and right dorsolateral PFC, right dorsomedial PFC, right pre-supplementary motor area, right inferior parietal lobule, and left medial temporal gyrus. The regions that demonstrated significant positive linear relationships between the number of adolescent years using substances and connectivity with NAcc are nodes in the right frontoparietal network, which is central to cognitive control. The coupling of reward and cognitive control networks may be a mechanism through which earlier onset of substance use is related to brain function over time, a trajectory that may be implicated in subsequent substance use disorders. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Harmful drinking after job loss: a stronger association during the post-2008 economic crisis?

    Science.gov (United States)

    de Goeij, Moniek C M; Bruggink, Jan-Willem; Otten, Ferdy; Kunst, Anton E

    2017-06-01

    This study investigated, among the Dutch working population, whether job loss during the post-2008 economic crisis is associated with harmful drinking and whether this association is stronger than before the crisis. Repeated cross-sectional data from the Dutch Health Interview Survey 2004-2013 were used to define episodic drinking (≥6 glasses on 1 day ≥1/week) and chronic drinking (≥14 glasses/week for women and ≥21 for men). These data were linked to longitudinal data from tax registries, to measure the experience and duration of job loss during a 5-year working history. Before the crisis, job loss experience and duration were not associated with harmful drinking. During the crisis, job loss for more than 6 months was associated with episodic drinking [OR 1.40 (95% CI 1.01; 1.94)], while current job loss was associated with chronic drinking [OR 1.43 (95% CI 1.03; 1.98)]. These associations were most clear in men and different between the pre-crisis and crisis period (p interaction = 0.023 and 0.035, respectively). The results suggest that economic crises strengthen the potential impact of job loss on harmful drinking, predominately among men.

  9. Mamografia com contraste

    OpenAIRE

    Baptista, Rita; Silva, Carina; Reis, Cláudia

    2016-01-01

    O estudo pretendeu apresentar as indicações clínicas, vantagens e princípios da mamografia com contraste, identificar as evoluyções tecnológicas para a mamografia com contraste e caracterizar as práticas e os desafios dos técnicos de radiologia do Hospital de Santarém (único no país a utilizar esta técnica). O cancro da mama é uma das principais causas de morte nas mulheres, em todo o mundo, mas principalmente nos Estados Unidos da América, Canadá, Europa Ocidental e Austrália. Em Portugal, e...

  10. Current iodinated contrast media

    International Nuclear Information System (INIS)

    Stacul, F.

    2001-01-01

    The number of scientific papers on iodinated contrast media is declining. Indeed, comparative trials between high-osmolality and low-osmolality agents largely showed the higher safety and tolerability of the latter, and this is no longer a matter of discussion. Only financial constraints could prevent a total conversion to low-osmolality agents. Research comparing low-osmolality (nonionic monomers, ionic dimer) and iso-osmolality contrast media (nonionic dimers) are still ongoing. Both classes of nonionic compounds proved safer than the ionic dimer. The relative merits of nonionic monomers and nonionic dimers are a matter for debate, and criteria for a selective use of different agents for different procedures could be discussed. (orig.)

  11. Anisotropic contrast optical microscope.

    Science.gov (United States)

    Peev, D; Hofmann, T; Kananizadeh, N; Beeram, S; Rodriguez, E; Wimer, S; Rodenhausen, K B; Herzinger, C M; Kasputis, T; Pfaunmiller, E; Nguyen, A; Korlacki, R; Pannier, A; Li, Y; Schubert, E; Hage, D; Schubert, M

    2016-11-01

    An optical microscope is described that reveals contrast in the Mueller matrix images of a thin, transparent, or semi-transparent specimen located within an anisotropic object plane (anisotropic filter). The specimen changes the anisotropy of the filter and thereby produces contrast within the Mueller matrix images. Here we use an anisotropic filter composed of a semi-transparent, nanostructured thin film with sub-wavelength thickness placed within the object plane. The sample is illuminated as in common optical microscopy but the light is modulated in its polarization using combinations of linear polarizers and phase plate (compensator) to control and analyze the state of polarization. Direct generalized ellipsometry data analysis approaches permit extraction of fundamental Mueller matrix object plane images dispensing with the need of Fourier expansion methods. Generalized ellipsometry model approaches are used for quantitative image analyses. These images are obtained from sets of multiple images obtained under various polarizer, analyzer, and compensator settings. Up to 16 independent Mueller matrix images can be obtained, while our current setup is limited to 11 images normalized by the unpolarized intensity. We demonstrate the anisotropic contrast optical microscope by measuring lithographically defined micro-patterned anisotropic filters, and we quantify the adsorption of an organic self-assembled monolayer film onto the anisotropic filter. Comparison with an isotropic glass slide demonstrates the image enhancement obtained by our method over microscopy without the use of an anisotropic filter. In our current instrument, we estimate the limit of detection for organic volumetric mass within the object plane of ≈49 fg within ≈7 × 7 μm 2 object surface area. Compared to a quartz crystal microbalance with dissipation instrumentation, where contemporary limits require a total load of ≈500 pg for detection, the instrumentation demonstrated here improves

  12. Serum albumin coating of demineralized bone matrix results in stronger new bone formation.

    Science.gov (United States)

    Horváthy, Dénes B; Vácz, Gabriella; Szabó, Tamás; Szigyártó, Imola C; Toró, Ildikó; Vámos, Boglárka; Hornyák, István; Renner, Károly; Klára, Tamás; Szabó, Bence T; Dobó-Nagy, Csaba; Doros, Attila; Lacza, Zsombor

    2016-01-01

    Blood serum fractions are hotly debated adjuvants in bone replacement therapies. In the present experiment, we coated demineralized bone matrices (DBM) with serum albumin and investigated stem cell attachment in vitro and bone formation in a rat calvaria defect model. In the in vitro experiments, we observed that significantly more cells adhere to the serum albumin coated DBMs at every time point. In vivo bone formation with albumin coated and uncoated DBM was monitored biweekly by computed tomography until 11 weeks postoperatively while empty defects served as controls. By the seventh week, the bone defect in the albumin group was almost completely closed (remaining defect 3.0 ± 2.3%), while uncoated DBM and unfilled control groups still had significant defects (uncoated: 40.2 ± 9.1%, control: 52.4 ± 8.9%). Higher density values were also observed in the albumin coated DBM group. In addition, the serum albumin enhanced group showed significantly higher volume of newly formed bone in the microCT analysis and produced significantly higher breaking force and stiffness compared to the uncoated grafts (peak breaking force: uncoated: 15.7 ± 4 N, albumin 46.1 ± 11 N). In conclusion, this investigation shows that implanting serum albumin coated DBM significantly reduces healing period in nonhealing defects and results in mechanically stronger bone. These results also support the idea that serum albumin coating provides a convenient milieu for stem cell function, and a much improved bone grafting success can be achieved without the use of exogenous stem cells. © 2015 Wiley Periodicals, Inc.

  13. Association Between Self-Esteem and Depressive Symptoms Is Stronger Among Black than White Older Adults.

    Science.gov (United States)

    Assari, Shervin

    2017-08-01

    Although poor self-esteem is a core component of depression, we still do not know if racial and ethnic groups differ in the magnitude of this link. This study compared Black and White older adults on the association between self-esteem and depressive symptoms. With a cross-sectional design, this study enrolled 1493 older individuals (age 66 or more) from the 2001 Religion, Aging, and Health Survey, a nationally representative study in the United States. Participants were either Blacks (n = 734) or Whites (n = 759). Depressive symptoms and self-esteem were measured using brief measures of the Center for Epidemiological Studies-Depression scale (CES-D) and the Rosenberg Self-Esteem Scale, respectively. Demographics, socioeconomics, and self-rated health (SRH) were covariates and self-identified race was the moderator. Linear regression models were used for data analysis. Low self-esteem was associated with more depressive symptoms (B = 0.17, 95 % CI 0.15-0.28), above and beyond all covariates. We found a significant and positive interaction between race (Black) and poor self-esteem on depressive symptoms (B = 0.34, 95 % CI 0.17-0.36), suggesting a stronger association between self-esteem and depressive symptoms among Blacks compared to Whites. Although low self-esteem is associated with higher depressive symptoms in both Whites and Blacks (p self-esteem and high depressive symptoms are more closely associated among Blacks than Whites. It is not clear whether depression leaves a larger scar on self-esteem for Blacks, or Blacks are more vulnerable to the effect of low self-esteem on depression.

  14. The bigger, the stronger? Insights from muscle architecture and nervous characteristics in obese adolescent girls.

    Science.gov (United States)

    Garcia-Vicencio, S; Coudeyre, E; Kluka, V; Cardenoux, C; Jegu, A-G; Fourot, A-V; Ratel, S; Martin, V

    2016-02-01

    Young obese youth are generally stronger than lean youth. This has been linked to the loading effect of excess body mass, acting as a training stimulus comparable to strength training. Whether this triggers specific adaptations of the muscle architecture (MA) and voluntary activation (VA) that could account for the higher strength of obese subjects remains unknown. MA characteristics (that is, pennation angle (PA), fascicle length (FL) and muscle thickness (MT)) and muscle size (that is, anatomical cross-sectional area (ACSA)) of the knee extensor (KE) and plantar flexor (PF) muscles were evaluated in 12 obese and 12 non-obese adolescent girls (12-15 years). Maximal isometric torque and VA of the KE and PF muscles were also assessed. Results revealed higher PA (Pmuscles in obese girls. Moreover, obese individuals produced a higher absolute torque than their lean counterparts on the KE (224.6±39.5 vs 135.7±32.7 N m, respectively; Pmuscles (73.3±16.5 vs 44.5±6.2 N m; Pmuscles (r=0.45-0.55, P<0.05-0.01). MVC was also correlated with VA (KE: r=0.44, P<0.05; PF: r=0.65, P<0.001) and segmental lean mass (KE: r=0.48, P<0.05; PF: r=0.57, P<0.01). This study highlighted favorable muscular and nervous adaptations to obesity that account for the higher strength of obese youth. The excess of body mass supported during daily activities could act as a chronic training stimulus responsible for these adaptations.

  15. Contrast Invariant SNR

    DEFF Research Database (Denmark)

    Weiss, Pierre; Escande, Paul; Dong, Yiqiu

    We design an image quality measure independent of local contrast changes, which constitute simple models of illumination changes. Given two images, the algorithm provides the image closest to the first one with the component tree of the second. This problem can be cast as a specific convex progra...... algorithms based on interior point methods. The algorithm has potential applications in change detection, color image processing or image fusion. A Matlab implementation is available at http://www.math.univ-toulouse.fr/_weiss/PageCodes.html....

  16. Bare quantifier fronting as contrastive topicalization

    Directory of Open Access Journals (Sweden)

    Ion Giurgea

    2015-11-01

    Full Text Available I argue that indefinites (in particular bare quantifiers such as ‘something’, ‘somebody’, etc. which are neither existentially presupposed nor in the restriction of a quantifier over situations, can undergo topicalization in a number of Romance languages (Catalan, Italian, Romanian, Spanish, but only if the sentence contains “verum” focus, i.e. focus on a high degree of certainty of the sentence. I analyze these indefinites as contrastive topics, using Büring’s (1999 theory (where the term ‘S-topic’ is used for what I call ‘contrastive topic’. I propose that the topic is evaluated in relation to a scalar set including generalized quantifiers such as {lP $x P(x, lP MANYx P(x, lP MOSTx P(x, lP “xP(x} or {lP $xP(x, lP P(a, lP P(b …}, and that the contrastive topic is the weakest generalized quantifier in this set. The verum focus, which is part of the “comment” that co-occurs with the “Topic”, introduces a set of alternatives including degrees of certainty of the assertion. The speaker asserts that his claim is certainly true or highly probable, contrasting it with stronger claims for which the degree of probability is unknown. This explains the observation that in downward entailing contexts, the fronted quantified DPs are headed by ‘all’ or ‘many’, whereas ‘some’, small numbers or ‘at least n’ appear in upward entailing contexts. Unlike other cases of non-specific topics, which are property topics, these are quantifier topics: the topic part is a generalized quantifier, the comment is a property of generalized quantifiers. This explains the narrow scope of the fronted quantified DP.

  17. Bell inequalities stronger than the Clauser-Horne-Shimony-Holt inequality for three-level isotropic states

    International Nuclear Information System (INIS)

    Ito, Tsuyoshi; Imai, Hiroshi; Avis, David

    2006-01-01

    We show that some two-party Bell inequalities with two-valued observables are stronger than the CHSH inequality for 3x3 isotropic states in the sense that they are violated by some isotropic states in the 3x3 system that do not violate the CHSH inequality. These Bell inequalities are obtained by applying triangular elimination to the list of known facet inequalities of the cut polytope on nine points. This gives a partial solution to an open problem posed by Collins and Gisin. The results of numerical optimization suggest that they are candidates for being stronger than the I 3322 Bell inequality for 3x3 isotropic states. On the other hand, we found no Bell inequalities stronger than the CHSH inequality for 2x2 isotropic states. In addition, we illustrate an inclusion relation among some Bell inequalities derived by triangular elimination

  18. Phase Contrast Imaging

    DEFF Research Database (Denmark)

    1996-01-01

    The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift phi is less than 1 radian. An improved method based on a simple imaging operation...... phasors attain predetermined values for predetermined spatial frequencies, and the phasor value of the specific resolution element of the spatial phase mask corresponds to a distinct intensity level of the image of the resolution element in the intensity pattern, and a spatial phase filter for phase...... shifting of a part of the electromagntic radiation, in combination with an imaging system for generation of the intensity pattern by interference in the image plane of the imaging system between the part of the electromagnetic raidation that has been phase shifted by the phase filter and the remaining part...

  19. Paramagnetic contrast material

    International Nuclear Information System (INIS)

    McNamara, M.T.

    1987-01-01

    Paramagnetic contrast materials have certainly demonstrated clinical utility in a variety of organ systems for improved detection of various neoplastic, inflammatory, infectious, and physiologic abnormalities. Although the more commonly employed extracellular agents, such as Gd-DTPA, have been quite safe and useful, particularly in the CNS, it is almost certain that other substances will achieve more success in various other organs, such as iron oxides in the reticuloendothelial system and persisting extracellular agents in the cardiovascular system. Finally, as MRI technology continues to evolve, producing such exciting new sequences as gradient-echo fast scans, the roles of currently existing and newly discovered paramagnetic pharmaceuticals must be continuously reevaluated both to obtain maximum clinical benefit and to guide the search for newer agents that may further optimize the diagnostic efficacy of MRI

  20. New MR contrast agent

    International Nuclear Information System (INIS)

    Grossman, C.D.; Subramanian, G.; Schneider, R.; Szeverenyi, N.E.; Rosenbaum, A.M.; Gagne, G.; Tillapaugh-Fay, G.; Berlin, R.; Ritter-Hrncirik, C.; Yu, S.

    1990-01-01

    This paper evaluates an MR contrast agent-meglumine tris-(2,6-dicarboxypyridine) gadolinium (III) or gadolinium dipicolinate (Gd-DPC)-produced in-house. Rats were anesthetized with pentobarbital. For renal imaging, bowel motion artifact was minimized with glucagon (0.014 mg/kg, intravenous (IV)). Enhanced images were generated on a 2-T chemical shift imaging system with a 31-cm horizontal bore magnet after IV injection of Gd-DPC (100 μM/kg). Coronal sections of the kidneys and sagittal sections of the brain, 2 mm thick, were made. Six to eight excitations and 128 or 356 phase-encoding steps were used for each image. Control animals were injected with equivalent doses of gadopentetate dimeglumine

  1. Interocularly merged face percepts eliminate binocular rivalry

    NARCIS (Netherlands)

    Klink, P. Christiaan; Boucherie, Daphne; Denys, Damiaan; Roelfsema, Pieter R.; Self, Matthew W.

    2017-01-01

    Faces are important visual objects for humans and other social animals. A complex network of specialized brain areas is involved in the recognition and interpretation of faces. This network needs to strike a balance between being sensitive enough to distinguish between different faces with similar

  2. The survival-reproduction association becomes stronger when conditions are good.

    Science.gov (United States)

    Robert, Alexandre; Bolton, Mark; Jiguet, Frédéric; Bried, Joël

    2015-11-07

    Positive covariations between survival and reproductive performance (S-R covariation) are generally interpreted in the context of fixed or dynamic demographic heterogeneity (i.e. persistent differences between individuals, or dynamic variation in resource acquisition), but the processes underlying covariations are still unknown. We used multi-event modelling to investigate how environmental and individual features influence S-R covariation patterns in a long-lived seabird, the Monteiro's storm petrel (Oceanodroma monteiroi). Our analysis reveals that a strong positive association between individual breeding success and subsequent survival occurs only when conditions are favourable to reproduction (in favourable years, in high-quality nests and in nest-faithful breeders). This finding reflects differences in the main causes of breeding failure and mortality under favourable and unfavourable conditions, which in turn lead to distinct patterns of S-R covariation. We suggest, in particular, that resource-related sources of demographic heterogeneity do not generate a strong S-R covariation, in contrast with hidden and unpredictable sources of variation. © 2015 The Author(s).

  3. Stronger communities? Changing prospects for community-led strategic planning in New Zealand

    Directory of Open Access Journals (Sweden)

    Bruno Brosnan

    2010-12-01

    Full Text Available New Zealand’s Local Government Act 2002 ushered in a new phase in local government, a phase that is best characterised by the term ‘empowerment’. Not only were councils empowered to promote social, economic, environmental and cultural well-being, in contrast with previous more prescriptive legislation, but citizens were empowered to engage in community-led strategic planning. In many respects the new statute reflected contemporary international public management trends in which governance is increasingly being conducted via networks of public and private actors. However, with the change of government from a centre-left Labour-led coalition to a centre-right National-led government following the November 2008 general election, it is less certain that local government and communities will continue to experience a strengthening of the pluralisation of governance that has been a feature of the past decade. This article argues that the potential disempowerment of local government, and possible attenuation of community-led strategic planning in New Zealand, comes at a time when the momentum for devolution to local government and other communities is increasing elsewhere.

  4. Stronger Association Between Valence- and Arousal Ratings of Affective Pictures with Older Age: Evidence for Variation Across Emotion Categories

    DEFF Research Database (Denmark)

    Mikkelsen, Mai Bjørnskov; Mehlsen, Mimi Yung; Lyby, Marlene Skovgaard

    A sample of older and younger adults rated affective pictures according to valence, arousal and emotion category (happiness, sadness and disgust). Results indicate that older age is associated with a stronger linear association between ratings of arousal and valence. Further, the strength...... of the association vary according to emotion category....

  5. Phase Contrast Imaging

    International Nuclear Information System (INIS)

    Menk, Ralf Hendrik

    2008-01-01

    All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift φ directly (using interference phenomena), the gradient ∇ φ , or the Laplacian ∇ 2 φ. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1,000-10,000 in the energy

  6. Stronger sexual selection in warmer waters: the case of a sex role reversed pipefish.

    Directory of Open Access Journals (Sweden)

    Nuno M Monteiro

    Full Text Available In order to answer broader questions about sexual selection, one needs to measure selection on a wide array of phenotypic traits, simultaneously through space and time. Nevertheless, studies that simultaneously address temporal and spatial variation in reproduction are scarce. Here, we aimed to investigate the reproductive dynamics of a cold-water pipefish simultaneously through time (encompassing variation within each breeding cycle and as individuals grow and space (by contrasting populations experiencing distinct water temperature regimes in order to test hypothesized differences in sexual selection. Even though the sampled populations inhabited locations with very different water temperature regimes, they exhibited considerable similarities in reproductive parameters. The most striking was the existence of a well-defined substructure in reproductive activity, where larger individuals reproduce for longer periods, which seemed dependent on a high temperature threshold for breeding rather than on the low temperatures that vary heavily according to latitude. Furthermore, the perceived disparities among populations, such as size at first reproduction, female reproductive investment, or degree of sexual size dimorphism, seemed dependent on the interplay between seawater temperature and the operational sex ratio (OSR. Contrary to our expectations of an enhanced opportunity for sexual selection in the north, we found the opposite: higher female reproductive investment coupled with increased sexual size dimorphism in warmer waters, implying that a prolonged breeding season does not necessarily translate into reduced sexual selection pressure. In fact, if the limited sex has the ability to reproduce either continuously or recurrently during the entire breeding season, an increased opportunity for sexual selection might arise from the need to compete for available partners under strongly biased OSRs across protracted breeding seasons. A more general

  7. Diversity has stronger top-down than bottom-up effects on decomposition.

    Science.gov (United States)

    Srivastava, Diane S; Cardinale, Bradley J; Downing, Amy L; Duffy, J Emmett; Jouseau, Claire; Sankaran, Mahesh; Wright, Justin P

    2009-04-01

    The flow of energy and nutrients between trophic levels is affected by both the trophic structure of food webs and the diversity of species within trophic levels. However, the combined effects of trophic structure and diversity on trophic transfer remain largely unknown. Here we ask whether changes in consumer diversity have the same effect as changes in resource diversity on rates of resource consumption. We address this question by focusing on consumer-resource dynamics for the ecologically important process of decomposition. This study compares the top-down effect of consumer (detritivore) diversity on the consumption of dead organic matter (decomposition) with the bottom-up effect of resource (detrital) diversity, based on a compilation of 90 observations reported in 28 studies. We did not detect effects of either detrital or consumer diversity on measures of detrital standing stock, and effects on consumer standing stock were equivocal. However, our meta-analysis indicates that reductions in detritivore diversity result in significant reductions in the rate of decomposition. Detrital diversity has both positive and negative effects on decomposition, with no overall trend. This difference between top-down and bottom-up effects of diversity is robust to different effect size metrics and could not be explained by differences in experimental systems or designs between detritivore and detrital manipulations. Our finding that resource diversity has no net effect on consumption in "brown" (detritus-consumer) food webs contrasts with previous findings from "green" (plant-herbivore) food webs and suggests that effects of plant diversity on consumption may fundamentally change after plant death.

  8. The Value of Contrast Echocardiography

    Directory of Open Access Journals (Sweden)

    Shannon C. Treiber

    2016-01-01

    Full Text Available Purpose: There is much evidence-based research proving the effectiveness of contrast echocardiography, but there are still questions and concerns about its specific uses. This study tested the effectiveness of contrast echocardiography in defining the left ventricular endocardial border. Methods: From 30 patients, a total of 60 echocardiograms –– 30 with and 30 without use of contrast –– were retrospectively reviewed by four blinded cardiologists with advanced training in echocardiography. No single cardiologist reviewed contrast and noncontrast images of the same patient. Each set of 30 echocardiograms was then studied for wall-motion scoring. Visualization of left ventricular wall segments and a global visualization confidence level of interpretation were recorded. Results: Of all wall segments (N = 510, 91% were visualized in echocardiograms with use of contrast, whereas 75% of the walls were visualized in echocardiograms without contrast (P < 0.001. Of 30 examinations, 17 contrast echocardiograms were read with high confidence compared to 6 without contrast use (P = 0.004. The number of walls visualized with contrast was increased in 18 patients (60%, whereas noncontrast echocardiograms yielded more visualized walls in 6 patients (20%, P = 0.002. Conclusions: This study demonstrates that contrast is valuable to echocardiographic imaging. Its use should be supported throughout echocardiography clinics and encouraged in certain patients for whom resting and stress echocardiography results without contrast often prove uninterpretable.

  9. Effects of computed tomography contrast medium factors on contrast enhancement

    International Nuclear Information System (INIS)

    Terasawa, Kazuaki; Hatcho, Atsushi; Okuda, Itsuko

    2011-01-01

    The various nonionic iodinated contrast media used in contrast computed tomography (CT) studies differ in terms of their composition, characteristics, and iodine concentration (mgI/ml), as well as the volume injected (ml). Compared with ionic iodinated contrast media, nonionic iodinated contrast media are low-osmolar agents, with different agents having different osmotic pressures. Using a custom-made phantom incorporating a semipermeable membrane, the osmotic flow rate (hounsfield unit (HU)/s) could easily be measured based on the observed increase in CT numbers, and the relationship between the osmotic pressure and the osmotic flow rate could be obtained (r 2 =0.84). In addition, taking the effects of patient size into consideration, the levels of contrast enhancement in the abdominal aorta (AA) and inferior vena cava (IVC) were compared among four types of CT contrast medium. The results showed differences in contrast enhancement in the IVC during the equilibrium phase depending on the type of contrast medium used. It was found that the factors responsible for the differences observed in enhancement in the IVC were the osmotic flow rate and the volume of the blood flow pathways in the circulatory system. It is therefore considered that the reproducibility of contrast enhancement is likely to be reduced in the examination of parenchymal organs, in which scanning must be performed during the equilibrium phase, even if the amount of iodine injected per unit body weight (mgI/kg) is maintained at a specified level. (author)

  10. Contrast-enhanced endoscopic ultrasonography

    DEFF Research Database (Denmark)

    Reddy, Nischita K; Ioncica, Ana Maria; Saftoiu, Adrian

    2011-01-01

    Contrast agents are increasingly being used to characterize the vasculature in an organ of interest, to better delineate benign from malignant pathology and to aid in staging and directing therapeutic procedures. We review the mechanisms of action of first, second and third generation contrast...... agents and their use in various endoscopic procedures in the gastrointestinal tract. Various applications of contrast-enhanced endoscopic ultrasonography include differentiating benign from malignant mediastinal lymphadenopathy, assessment of depth of invasion of esophageal, gastric and gall bladder...

  11. Extracellular gadolinium contrast agents: Differences in stability

    International Nuclear Information System (INIS)

    Morcos, S.K.

    2008-01-01

    Extracellular gadolinium contrast agents (Gd-CA) are either linear or macrocyclic chelates available as ionic or non-ionic preparations. The molecular structure whether cyclic or linear and ionicity determines the stability of Gd-CA. Linear chelates are flexible open chains which do not offer a strong binding to Gd 3+ . In contrast, the macrocyclic chelates offer a strong binding to Gd 3+ by the virtue of being preorganized rigid rings of almost optimal size to cage the gadolinium atom. Non-ionic preparations are also less stable in comparison to the ionic ones as the binding between Gd 3+ with the negatively charged carboxyl groups is stronger in comparison to that with amides or alcohol in the non-ionic preparations. According to stability constants and kinetic measurements, the most stable Gd-CM is the ionic-macrocyclic chelate Gd-DOTA and the least stable agents are the non-ionic linear chelates gadodiamide and gadoversetamide. In vivo data confirmed the low stability of non-ionic linear chelates but no significant difference was observed amongst the macrocyclic agents whether ionic (Gd-DOTA) or non-ionic such as Gd-HP-DO3A and Gd-BT-DO3A. The stability of Gd-CA seems to be an important factor in the pathogenesis of the serious complication of nephrogenic systemic fibrosis. Gd-CA of low stability are likely to undergo transmetallation and release free Gd ions that deposit in tissue and attract circulating fibrocytes to initiate the process of fibrosis. No cases of NSF have been observed so far after the exclusive use of the stable macrocyclic Gd-CA

  12. Properties of conventional contrast media

    International Nuclear Information System (INIS)

    Muetzel, W.

    1981-01-01

    A comprehensive overview is given of the properties of contrast media currently used in computed tomography (CT). The chemical structure of the compounds and the physicochemical properties derived therefrom are described. Emphasis is placed on the importance of the physicochemical properties of contrast media for tolerance and the pharmacokinetic behavior of compounds in the body. An outline is given of the basic ideas governing rational use of contrast media in CT, which result from complex, time-dependent distribution of contrast media in different tissue spaces. (Auth.)

  13. The new numbers contrast sensitivity chart for contrast sensitivity measurement

    Directory of Open Access Journals (Sweden)

    Bharkbhum Khambhiphant

    2011-10-01

    Conclusions: These charts show reasonable agreement and can be used interchangeably with the MARS. It is helpful for Thai people who can only read numbers in doing the test. We can use them in routinely contrast sensitivity measurement.

  14. Income inequality is associated with stronger social comparison effects: The effect of relative income on life satisfaction.

    Science.gov (United States)

    Cheung, Felix; Lucas, Richard E

    2016-02-01

    Previous research has shown that having rich neighbors is associated with reduced levels of subjective well-being, an effect that is likely due to social comparison. The current study examined the role of income inequality as a moderator of this relative income effect. Multilevel analyses were conducted on a sample of more than 1.7 million people from 2,425 counties in the United States. Results showed that higher income inequality was associated with stronger relative income effects. In other words, people were more strongly influenced by the income of their neighbors when income inequality was high. (c) 2016 APA, all rights reserved).

  15. Income Inequality Is Associated with Stronger Social Comparison Effects: The Effect of Relative Income on Life Satisfaction

    Science.gov (United States)

    Cheung, Felix; Lucas, Richard E.

    2015-01-01

    Previous research has shown that having rich neighbors is associated with reduced levels of subjective well-being, an effect that is likely due to social comparison. The current study examined the role of income inequality as a moderator of this relative income effect. Multilevel analyses were conducted on a sample of over 1.7 million people from 2,425 counties in the United States. Results showed that higher income inequality was associated with stronger relative income effects. In other words, people were more strongly influenced by the income of their neighbors when income inequality was high. PMID:26191957

  16. Contrast-enhanced peripheral MRA. Technique and contrast agents

    International Nuclear Information System (INIS)

    Nielsen, Yousef W.; Thomsen, Henrik S.

    2012-01-01

    In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with peripheral arterial disease. This review presents current concepts in peripheral CE-MRA with emphasis on MRI technique and contrast agents. Peripheral CE-MRA is defined as an MR angiogram of the arteries from the aortic bifurcation to the feet. Advantages of CE-MRA include minimal invasiveness and lack of ionizing radiation. The basic technique employed for peripheral CE-MRA is the bolus-chase method. With this method a paramagnetic MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic field strength of the MRI system, receiver coil configuration, use of parallel imaging, contrast bolus timing technique, and k-space filling strategies. Furthermore, it is possible to optimize peripheral CE-MRA using venous compression techniques, hybrid scan protocols, time-resolved imaging, and steady-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal insufficiency. Using optimized technique and a stable MRI contrast agent, peripheral CE-MRA is a safe procedure with diagnostic accuracy close to that of conventional catheter X

  17. Adriamycin nephrosis and contrast media

    International Nuclear Information System (INIS)

    Thomsen, H.S.; Golman, K.; Hemmingsen, L.; Larsen, S.; Skaarup, P.; Koebenhavns Amts Sygehus, Herlev; Koebenhavns Amts Sygehus, Herlev; Centralsygehuset, Nykoebing Falster; Malmoe Allmaenna Sjukhus

    1990-01-01

    Urine profiles (albumin, glucose, NAG, LDH, GGT and sodium) were followed for 9 days after intravenous injection of either diatrizoate, iohexol, or saline in 27 Wistar rats with nephrosis induced by Adriamycin 42 days before. Another 9 rats exposed to neither Adriamycin nor contrast media served as controls. None of the contrast media caused further increased albuminuria of significance, whereas both induced significantly increased excretion of all 5 tubular components. The excretion of NAG and sodium was significantly higher following diatrizoate than following iohexol. From 24 h post injection there was no significantly greater excretion of any of the components after either diatrizoate or iohexol than after saline among the rats given Adriamycin. At the end of day 9 after contrast medium injection neither serum sodium, potassium, glucose, urea, creatinine, nor albumin revealed any contrast media related changes. Kidney histology showed quantitatively larger lesions in kidneys exposed to Adriamycin and contrast media than in kidneys exposed to Adriamycin and saline. There were no differences between the two contrast media groups. It is thus concluded, that both high osmolar ionic and low osmolar non-ionic contrast media cause temporary tubular dysfunction but no further glomerular dysfunction in rats with nephrosis induced by Adriamycin. The histologic findings indicate that both media may worsen non-reversible renal lesions. (orig.)

  18. Which global stock indices trigger stronger contagion risk in the Vietnamese stock market? Evidence using a bivariate analysis

    Directory of Open Access Journals (Sweden)

    Wang Kuan-Min

    2013-01-01

    Full Text Available This paper extends recent investigations into risk contagion effects on stock markets to the Vietnamese stock market. Daily data spanning October 9, 2006 to May 3, 2012 are sourced to empirically validate the contagion effects between stock markets in Vietnam, and China, Japan, Singapore, and the US. To facilitate the validation of contagion effects with market-related coefficients, this paper constructs a bivariate EGARCH model of dynamic conditional correlation coefficients. Using the correlation contagion test and Dungey et al.’s (2005 contagion test, we find contagion effects between the Vietnamese and four other stock markets, namely Japan, Singapore, China, and the US. Second, we show that the Japanese stock market causes stronger contagion risk in the Vietnamese stock market compared to the stock markets of China, Singapore, and the US. Finally, we show that the Chinese and US stock markets cause weaker contagion effects in the Vietnamese stock market because of stronger interdependence effects between the former two markets.

  19. The impact of gambling advertising: Problem gamblers report stronger impacts on involvement, knowledge, and awareness than recreational gamblers.

    Science.gov (United States)

    Hanss, Daniel; Mentzoni, Rune A; Griffiths, Mark D; Pallesen, Ståle

    2015-06-01

    Although there is a general lack of empirical evidence that advertising influences gambling participation, the regulation of gambling advertising is hotly debated among academic researchers, treatment specialists, lobby groups, regulators, and policymakers. This study contributes to the ongoing debate by investigating perceived impacts of gambling advertising in a sample of gamblers drawn from the general population in Norway (n = 6,034). Three dimensions of advertising impacts were identified, representing perceived impacts on (a) gambling-related attitudes, interest, and behavior ("involvement"); (b) knowledge about gambling options and providers ("knowledge"); and (c) the degree to which people are aware of gambling advertising ("awareness"). Overall, impacts were strongest for the knowledge dimension, and, for all 3 dimensions, the impact increased with level of advertising exposure. Those identified as problem gamblers in the sample (n = 57) reported advertising impacts concerning involvement more than recreational gamblers, and this finding was not attributable to differences in advertising exposure. Additionally, younger gamblers reported stronger impacts on involvement and knowledge but were less likely to agree that they were aware of gambling advertising than older gamblers. Male gamblers were more likely than female gamblers to report stronger impacts on both involvement and knowledge. These findings are discussed with regard to existing research on gambling advertising as well as their implications for future research and policy-making. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  20. Removal of proprioception by BCI raises a stronger body ownership illusion in control of a humanlike robot.

    Science.gov (United States)

    Alimardani, Maryam; Nishio, Shuichi; Ishiguro, Hiroshi

    2016-09-22

    Body ownership illusions provide evidence that our sense of self is not coherent and can be extended to non-body objects. Studying about these illusions gives us practical tools to understand the brain mechanisms that underlie body recognition and the experience of self. We previously introduced an illusion of body ownership transfer (BOT) for operators of a very humanlike robot. This sensation of owning the robot's body was confirmed when operators controlled the robot either by performing the desired motion with their body (motion-control) or by employing a brain-computer interface (BCI) that translated motor imagery commands to robot movement (BCI-control). The interesting observation during BCI-control was that the illusion could be induced even with a noticeable delay in the BCI system. Temporal discrepancy has always shown critical weakening effects on body ownership illusions. However the delay-robustness of BOT during BCI-control raised a question about the interaction between the proprioceptive inputs and delayed visual feedback in agency-driven illusions. In this work, we compared the intensity of BOT illusion for operators in two conditions; motion-control and BCI-control. Our results revealed a significantly stronger BOT illusion for the case of BCI-control. This finding highlights BCI's potential in inducing stronger agency-driven illusions by building a direct communication between the brain and controlled body, and therefore removing awareness from the subject's own body.

  1. Contrast-enhanced endoscopic ultrasonography

    DEFF Research Database (Denmark)

    Reddy, Nischita K; Ioncică, Ana Maria; Săftoiu, Adrian

    2011-01-01

    Contrast agents are increasingly being used to characterize the vasculature in an organ of interest, to better delineate benign from malignant pathology and to aid in staging and directing therapeutic procedures. We review the mechanisms of action of first, second and third generation contrast...... agents and their use in various endoscopic procedures in the gastrointestinal tract. Various applications of contrast-enhanced endoscopic ultrasonography include differentiating benign from malignant mediastinal lymphadenopathy, assessment of depth of invasion of esophageal, gastric and gall bladder...... cancers and visualization of the portal venous system and esophageal varices. In addition, contrast agents can be used to differentiate pancreatic lesions. The use of color Doppler further increases the ability to diagnose and differentiate various pancreatic malignancies. The sensitivity of power Doppler...

  2. Contrast-enhanced peripheral MRA

    DEFF Research Database (Denmark)

    Nielsen, Yousef W; Thomsen, Henrik S

    2012-01-01

    MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic......-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged...... intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal...

  3. Investigation of contrast agent dosage for perfusion-weighted MRI

    International Nuclear Information System (INIS)

    Erb, G.; Benner, T.; Heiland, S.; Reith, W.; Sartor, K.; Forsting, M.

    1997-01-01

    Purpose: In this study we investigated, whether increasing the dosage of a paramagnetic contrast agent results in a stronger signal decrease in T 2 *-weighted perfusion sequences and therefore more meaningful parameter maps. Material and methods: In a prospective study bolus injection of gadolinium-DTPA was performed at dosages of 0.1, 0.2, and 0.3 mmol/kg body weight (BW) in 10 patients each. Before, during and after bolus injection 40 T 2 *-weighted images of a reference brain slice were acquired within 65.6 seconds on a 1.0 T clinical scanner and perfusion parameters were calculated. Results: Due to the limited signal decrease during bolus passage and the resulting low signal-difference-to-noise ratio (ΔS/N) no reliable differentiation of gray and white matter was possible at a contrast agent dosage of 0.1 mmol/kg BW. Only at higher dosages, both, signal decrease and ΔS/N were strong enough to allow differentiation of gray and white matter and to yield reliable parameter maps. Conclusion: For meaningful MR perfusion imaging at 1.0 T and with the given sequence a contrast agent dosage of at least 0.2 mmol/kg BW is necessary, if a 0.5-molar contrast agent is used. (orig.) [de

  4. Contrast Media: Are There Differences in Nephrotoxicity among Contrast Media?

    Science.gov (United States)

    2014-01-01

    Iodinated contrast agents are usually classified based upon their osmolality—high, low, and isosmolar. Iodinated contrast agents are also nephrotoxic in some but not all patients resulting in loss of glomerular filtration rate. Over the past 30 years, nephrotoxicity has been linked to osmolality although the precise mechanism underlying such a link has been elusive. Improvements in our understanding of the pathogenesis of nephrotoxicity and prospective randomized clinical trials have attempted to further explore the relationship between osmolality and nephrotoxicity. In this review, the basis for our current understanding that there are little if any differences in nephrotoxic potential between low and isosmolar contrast media will be detailed using data from clinical studies. PMID:24587997

  5. Immune indexes of larks from desert and temperate regions show weak associations with life history but stronger links to environmental variation in microbial abundance.

    Science.gov (United States)

    Horrocks, Nicholas P C; Hegemann, Arne; Matson, Kevin D; Hine, Kathryn; Jaquier, Sophie; Shobrak, Mohammed; Williams, Joseph B; Tinbergen, Joost M; Tieleman, B Irene

    2012-01-01

    Immune defense may vary as a result of trade-offs with other life-history traits or in parallel with variation in antigen levels in the environment. We studied lark species (Alaudidae) in the Arabian Desert and temperate Netherlands to test opposing predictions from these two hypotheses. Based on their slower pace of life, the trade-off hypothesis predicts relatively stronger immune defenses in desert larks compared with temperate larks. However, as predicted by the antigen exposure hypothesis, reduced microbial abundances in deserts should result in desert-living larks having relatively weaker immune defenses. We quantified host-independent and host-dependent microbial abundances of culturable microbes in ambient air and from the surfaces of birds. We measured components of immunity by quantifying concentrations of the acute-phase protein haptoglobin, natural antibody-mediated agglutination titers, complement-mediated lysis titers, and the microbicidal ability of whole blood. Desert-living larks were exposed to significantly lower concentrations of airborne microbes than temperate larks, and densities of some bird-associated microbes were also lower in desert species. Haptoglobin concentrations and lysis titers were also significantly lower in desert-living larks, but other immune indexes did not differ. Thus, contrary to the trade-off hypothesis, we found little evidence that a slow pace of life predicted increased immunological investment. In contrast, and in support of the antigen exposure hypothesis, associations between microbial exposure and some immune indexes were apparent. Measures of antigen exposure, including assessment of host-independent and host-dependent microbial assemblages, can provide novel insights into the mechanisms underlying immunological variation.

  6. How to misuse echo contrast

    Directory of Open Access Journals (Sweden)

    Missios Anna

    2009-01-01

    Full Text Available Abstract Background Primary intracardiac tumours are rare, there are however several entities that can mimic tumours. Contrast echocardiography has been suggested to aid the differentiation of various suspected masses. We present a case where transthoracic echocardiography completely misdiagnosed a left atrial mass, partly due to use of echo contrast. Case presentation An 80 year-old woman was referred for transthoracic echocardiography because of one-month duration of worsening of dyspnoea. Transthoracic echocardiography displayed a large echodense mass in the left atrium. Intravenous injection of contrast (SonoVue, Bracco Inc., It indicated contrast-enhancement of the structure, suggesting tumour. Transesophageal echocardiography revealed, however, a completely normal finding in the left atrium. Subsequent gastroscopy examination showed a hiatal hernia. Conclusion It is noteworthy that the transthoracic echocardiographic exam completely misdiagnosed what seemed like a left atrial mass, which in part was an effect of the use of echo contrast. This example highlights that liberal use of transoesophageal echocardiography is often warranted if optimal display of cardiac structures is desired.

  7. Collective Nostalgia Is Associated With Stronger Outgroup-Directed Anger and Participation in Ingroup-Favoring Collective Action

    Directory of Open Access Journals (Sweden)

    Wing-Yee Cheung

    2017-08-01

    Full Text Available Collective nostalgia refers to longing for the way society used to be. We tested whether collective nostalgia is associated with ingroup-favoring collective action and whether this association is mediated by outgroup-directed anger and outgroup-directed contempt. We conducted an online study of Hong Kong residents (N = 111 during a large-scale democratic social movement, the Umbrella Movement, that took place in Hong Kong in 2014 in response to proposed electoral reforms by the Chinese government in Mainland China. Reported collective nostalgia for Hong Kong’s past was high in our sample and collective nostalgia predicted stronger involvement in ingroup-favoring collective action, and it did so indirectly via higher intensity of outgroup-directed anger (but not through outgroup-directed contempt. We argue that collective nostalgia has implications for strengthening ingroup-serving collective action, and we highlight the importance of arousal of group-based emotions in this process.

  8. Bactericidal activity of LFchimera is stronger and less sensitive to ionic strength than its constituent lactoferricin and lactoferrampin peptides.

    Science.gov (United States)

    Bolscher, Jan G M; Adão, Regina; Nazmi, Kamran; van den Keybus, Petra A M; van 't Hof, Wim; Nieuw Amerongen, Arie V; Bastos, Margarida; Veerman, Enno C I

    2009-01-01

    The innate immunity factor lactoferrin harbours two antimicrobial moieties, lactoferricin and lactoferrampin, situated in close proximity in the N1 domain of the molecule. Most likely they cooperate in many of the beneficial activities of lactoferrin. To investigate whether chimerization of both peptides forms a functional unit we designed a chimerical structure containing lactoferricin amino acids 17-30 and lactoferrampin amino acids 265-284. The bactericidal activity of this LFchimera was found to be drastically stronger than that of the constituent peptides, as was demonstrated by the need for lower dose, shorter incubation time and less ionic strength dependency. Likewise, strongly enhanced interaction with negatively charged model membranes was found for the LFchimera relative to the constituent peptides. Thus, chimerization of the two antimicrobial peptides resembling their structural orientation in the native molecule strikingly improves their biological activity.

  9. Bilingual recognition memory: stronger performance but weaker levels-of-processing effects in the less fluent language.

    Science.gov (United States)

    Francis, Wendy S; Gutiérrez, Marisela

    2012-04-01

    The effects of bilingual proficiency on recognition memory were examined in an experiment with Spanish-English bilinguals. Participants learned lists of words in English and Spanish under shallow- and deep-encoding conditions. Overall, hit rates were higher, discrimination greater, and response times shorter in the nondominant language, consistent with effects previously observed for lower frequency words. Levels-of-processing effects in hit rates, discrimination, and response time were stronger in the dominant language. Specifically, with shallow encoding, the advantage for the nondominant language was larger than with deep encoding. The results support the idea that memory performance in the nondominant language is impacted by both the greater demand for cognitive resources and the lower familiarity of the words.

  10. Strategic Factors Influencing National and Regional Systems of Innovation: A Case of Weaker NSI with Stronger RSI

    Directory of Open Access Journals (Sweden)

    Pir Roshanuddin Shah Rashdi

    2015-04-01

    Full Text Available The issues of relationship between NSI ((National System of Innovation and RSI (Regional System of Innovation are not well reported with innovation policy research. That is, whether the NSI is the system on top of RSI, or the importance of regions make stronger NSIs. Therefore, it raises concern regarding development of strategic relationship between these two. For this, two cases ? Catalonia (Spain and N Ireland (the UK, have been selected based on theoretical sampling. Key economic indicators have been identified and have been quantitatively analyzed. The evidence suggests that strong NSI has positive influence on RSI. In addition to that, the concentration of knowledge and promotion of institutions may be strategically established and then needed resources may be injected to produce high quality human resources. There is, however, need for more comprehensive studies to be conducted in order to validate the results of this research

  11. The sigh of the oppressed: The palliative effects of ideology are stronger for people living in highly unequal neighbourhoods.

    Science.gov (United States)

    Sengupta, Nikhil K; Greaves, Lara M; Osborne, Danny; Sibley, Chris G

    2017-09-01

    Ideologies that legitimize status hierarchies are associated with increased well-being. However, which ideologies have 'palliative effects', why they have these effects, and whether these effects extend to low-status groups remain unresolved issues. This study aimed to address these issues by testing the effects of the ideology of Symbolic Prejudice on well-being among low- and high-status ethnic groups (4,519 Europeans and 1,091 Māori) nested within 1,437 regions in New Zealand. Results showed that Symbolic Prejudice predicted increased well-being for both groups, but that this relationship was stronger for those living in highly unequal neighbourhoods. This suggests that it is precisely those who have the strongest need to justify inequality that accrue the most psychological benefit from subscribing to legitimizing ideologies. © 2017 The British Psychological Society.

  12. Elite level rhythmic gymnasts have significantly more and stronger pain than peers of similar age: a prospective study.

    Science.gov (United States)

    Sabeti, Manuel; Jeremian, Lusine; Graf, Alexandra; Kandelhart, Robert

    2015-01-01

    Rhythmic gymnastics (RG) unites aesthetic, ballet-like motion, and all aspects of gymnastics. To reach elite level, girls begin at early age the intensive training. To date it is unclear if such demanding training influences the incidence and intensity of painful overuse injuries. The purpose of this study is to analyze anatomical painful regions and pain intensity in elite level rhythmic gymnasts (elRG) and compare results with an age-matched control group (CG). This prospective field study was carried out at the European Championship in RG 2013 (218 participating athletes, Vienna, Austria). Volunteering athletes were interviewed according to a preformed questionnaire. As CG secondary school pupils without any competitive sports experience were analyzed accordingly. Overall, 243 young females (144 elRG/66 % of all participants and 99 CG) were observed. ElRGs were significantly (s.) smaller, lighter, and had s. stronger pain (p < 0.001). A total of 72 % of athletes reported to have at least one painful body region compared with 52 % of CG (p < 0.001). ElRG had nearly three times more serious injuries than the CG. In all 23 % off all elRG reported to have had no access to professional medical care. ElRGs were s. more frequently (25 vs 9 %) affected at the lumbar spine and the ankle joint (17.4 vs 7 %). To our knowledge, this trial analyzes the largest cohort of elRG to date. Hence, it is clearly alluded that intensive training in RG is a significant factor causing more and stronger pain than in a CG.

  13. Multiscale image contrast amplification (MUSICA)

    Science.gov (United States)

    Vuylsteke, Pieter; Schoeters, Emile P.

    1994-05-01

    This article presents a novel approach to the problem of detail contrast enhancement, based on multiresolution representation of the original image. The image is decomposed into a weighted sum of smooth, localized, 2D basis functions at multiple scales. Each transform coefficient represents the amount of local detail at some specific scale and at a specific position in the image. Detail contrast is enhanced by non-linear amplification of the transform coefficients. An inverse transform is then applied to the modified coefficients. This yields a uniformly contrast- enhanced image without artefacts. The MUSICA-algorithm is being applied routinely to computed radiography images of chest, skull, spine, shoulder, pelvis, extremities, and abdomen examinations, with excellent acceptance. It is useful for a wide range of applications in the medical, graphical, and industrial area.

  14. Contrast enhancement CT by iopamidol

    International Nuclear Information System (INIS)

    Mori, Masaki; Makita, Nobue; Yanai, Kyoko

    1984-01-01

    In order to evaluate the contrast enhancement effect and safety of iopamidol (IOP) in CT examination, IOP was compared with angiographin (AG). In the liver and abdominal aorta, peak CT values were obtained earlier and were higher in the group with AG than in the group with IOP. However, CT values in the group with IOP decreased a little more slowly than those in the group with AG. There was no significant difference in the effect on contrast enhancement between the groups. Intravenous injection of IOP caused lower degree of burning sensation than that of AG, and some of the patients with IOP did not feel burning sensation at all. Changes in clinical laboratory values were slight before and after intravenous injection of IOP. These results suggest that IOP is satisfactory in terms of safety and effect on contrast enhancement in CT examination. (Namekawa, K.)

  15. Contrast-guided image interpolation.

    Science.gov (United States)

    Wei, Zhe; Ma, Kai-Kuang

    2013-11-01

    In this paper a contrast-guided image interpolation method is proposed that incorporates contrast information into the image interpolation process. Given the image under interpolation, four binary contrast-guided decision maps (CDMs) are generated and used to guide the interpolation filtering through two sequential stages: 1) the 45(°) and 135(°) CDMs for interpolating the diagonal pixels and 2) the 0(°) and 90(°) CDMs for interpolating the row and column pixels. After applying edge detection to the input image, the generation of a CDM lies in evaluating those nearby non-edge pixels of each detected edge for re-classifying them possibly as edge pixels. This decision is realized by solving two generalized diffusion equations over the computed directional variation (DV) fields using a derived numerical approach to diffuse or spread the contrast boundaries or edges, respectively. The amount of diffusion or spreading is proportional to the amount of local contrast measured at each detected edge. The diffused DV fields are then thresholded for yielding the binary CDMs, respectively. Therefore, the decision bands with variable widths will be created on each CDM. The two CDMs generated in each stage will be exploited as the guidance maps to conduct the interpolation process: for each declared edge pixel on the CDM, a 1-D directional filtering will be applied to estimate its associated to-be-interpolated pixel along the direction as indicated by the respective CDM; otherwise, a 2-D directionless or isotropic filtering will be used instead to estimate the associated missing pixels for each declared non-edge pixel. Extensive simulation results have clearly shown that the proposed contrast-guided image interpolation is superior to other state-of-the-art edge-guided image interpolation methods. In addition, the computational complexity is relatively low when compared with existing methods; hence, it is fairly attractive for real-time image applications.

  16. Iodinated contrast media nephrotoxicity. Nephrotoxicite des produits de contraste iodes

    Energy Technology Data Exchange (ETDEWEB)

    Meyrier, A. (Hopital Avicenne, 93 - Bobigny (France))

    1994-01-01

    In the late seventies, iodinated contrast agents (ICA) were considered to be a major cause of acute iatrogenic renal failure. Over the last decade new contrast agents have been synthesized, nonionic and less hyperosmolar. The incidence of acute renal failure due to ICAs, varies from 3.7 to 70% of cases according to the series, with an average figure of 10.2%. The pathophysiology of ICA nephrotoxicity was mainly studied in laboratory animal models. Three main factors are involved in an inducing ICA-mediated decrease in glomerular filtration rate: reduction of the renal plasma flow, a direct cytotoxic effect on renal tubular cells and erythrocyte alteration leading to intra-renal sludge. Excluding dysglobulinemias with urinary excretion of immunoglobulin light chains, which represent a special case of maximum nephrotoxicity, 4 main risk factors of renal toxicity have been identified in nondiabetic subjects: previous renal failure with serum creatinine levels greater than 140 [mu]mol per liter, extracellular dehydration, age over 60 and use of high doses of ICA and/or repeated ICA injections before serum creatinine levels return to baseline. Preventive measures for avoiding ICA nephrotoxicity are threefold: maintain or restore adequate hydration with saline infusion, stop NSAID treatment several days before ICA administration, and allow a 5 day interval before repeating contrast media injections. New, nonionic and moderately hyperosmolar contrast agents appear to be much less nephrotoxic than conventional ICAs in laboratory animals and in high-risk patients. It is advisable to select such contrast media for investigating high-risk patients. This approach was recently substantiated in well designed, randomized clinical studies which included more than 2 000 patients. (author).

  17. Quantitative contrast-enhanced mammography for contrast medium kinetics studies

    Science.gov (United States)

    Arvanitis, C. D.; Speller, R.

    2009-10-01

    Quantitative contrast-enhanced mammography, based on a dual-energy approach, aims to extract quantitative and temporal information of the tumour enhancement after administration of iodinated vascular contrast media. Simulations using analytical expressions and optimization of critical parameters essential for the development of quantitative contrast-enhanced mammography are presented. The procedure has been experimentally evaluated using a tissue-equivalent phantom and an amorphous silicon active matrix flat panel imager. The x-ray beams were produced by a tungsten target tube and spectrally shaped using readily available materials. Measurement of iodine projected thickness in mg cm-2 has been performed. The effect of beam hardening does not introduce nonlinearities in the measurement of iodine projected thickness for values of thicknesses found in clinical investigations. However, scattered radiation introduces significant deviations from slope equal to unity when compared with the actual iodine projected thickness. Scatter correction before the analysis of the dual-energy images provides accurate iodine projected thickness measurements. At 10% of the exposure used in clinical mammography, signal-to-noise ratios in excess of 5 were achieved for iodine projected thicknesses less than 3 mg cm-2 within a 4 cm thick phantom. For the extraction of temporal information, a limited number of low-dose images were used with the phantom incorporating a flow of iodinated contrast medium. The results suggest that spatial and temporal information of iodinated contrast media can be used to indirectly measure the tumour microvessel density and determine its uptake and washout from breast tumours. The proposed method can significantly improve tumour detection in dense breasts. Its application to perform in situ x-ray biopsy and assessment of the oncolytic effect of anticancer agents is foreseeable.

  18. Ultrasound Contrast Agent Microbubble Dynamics

    NARCIS (Netherlands)

    Overvelde, M.L.J.; Vos, Henk; de Jong, N.; Versluis, Michel; Paradossi, Gaio; Pellegretti, Paolo; Trucco, Andrea

    2010-01-01

    Ultrasound contrast agents are traditionally used in ultrasound-assisted organ perfusion imaging. Recently the use of coated microbubbles has been proposed for molecular imaging applications where the bubbles are covered with a layer of targeting ligands to bind specifically to their target cells.

  19. Color contrasting in radioscopy systems

    International Nuclear Information System (INIS)

    Lopaev, V.P.; Pavlov, S.V.; Nazarenko, V.G.

    1979-01-01

    Transformation principles for achromatic radioscopy control systems to color ones have been considered. Described is the developed ''Gamma 1'' roentgen-TV facility with color contrasting, which is based on the principle of analog conversion of brightness signal to a hue. By means of color channels amplifiers realized are the special amplitude characteristics, permitting in comparison with the common method of analogous transformation to obtain the greater number of hues within the identical range of brightnesses of image under investigation due to introducing purple colors. The investigation of amplitude resolution capability of color contrasting device has shown, that in the case of color contrasting of image the amplitude resolution is 1.7-1.8 time higher than in the case of achromatic one. Defectoscopic sensitivity during the testing of 5-20 mm thick steel products in the process of experimental-production tests turned out to be 1.1-1.3 time higher when using color contrasting of radioscopic image. Realization simplicity, high resolution, noise stability and wide functional possibilities of the facility show the prospects for its using during the quality control of welded joints in products of power engineering

  20. Giving Student Groups a Stronger Voice: Using Participatory Research and Action (PRA) to Initiate Change to a Curriculum

    Science.gov (United States)

    O'Neill, Geraldine; McMahon, Sinead

    2012-01-01

    Traditional student feedback mechanisms have been criticised for being teacher-centred in design and, in particular, for their absence of transparent follow-up actions. In contrast, this study describes the process and the evaluation of a participatory research and action (PRA) approach used in an undergraduate physiotherapy degree. This approach…

  1. In roots of Arabidopsis thaliana, the damage-associated molecular pattern AtPep1 is a stronger elicitor of immune signalling than flg22 or the chitin heptamer.

    Directory of Open Access Journals (Sweden)

    Lorenzo Poncini

    Full Text Available Plants interpret their immediate environment through perception of small molecules. Microbe-associated molecular patterns (MAMPs such as flagellin and chitin are likely to be more abundant in the rhizosphere than plant-derived damage-associated molecular patterns (DAMPs. We investigated how the Arabidopsis thaliana root interprets MAMPs and DAMPs as danger signals. We monitored root development during exposure to increasing concentrations of the MAMPs flg22 and the chitin heptamer as well as of the DAMP AtPep1. The tissue-specific expression of defence-related genes in roots was analysed using a toolkit of promoter::YFPN lines reporting jasmonic acid (JA-, salicylic acid (SA-, ethylene (ET- and reactive oxygen species (ROS- dependent signalling. Finally, marker responses were analysed during invasion by the root pathogen Fusarium oxysporum. The DAMP AtPep1 triggered a stronger activation of the defence markers compared to flg22 and the chitin heptamer. In contrast to the tested MAMPs, AtPep1 induced SA- and JA-signalling markers in the root and caused a severe inhibition of root growth. Fungal attack resulted in a strong activation of defence genes in tissues close to the invading fungal hyphae. The results collectively suggest that AtPep1 presents a stronger danger signal to the Arabidopsis root than the MAMPs flg22 and chitin heptamer.

  2. Strategies of Building a Stronger Sense of Community for Sustainable Neighborhoods: Comparing Neighborhood Accessibility with Community Empowerment Programs

    Directory of Open Access Journals (Sweden)

    Te-I Albert Tsai

    2014-05-01

    Full Text Available New Urbanist development in the U.S. aims at enhancing a sense of community and seeks to return to the design of early transitional neighborhoods which have pedestrian-oriented environments with retail shops and services within walking distances of housing. Meanwhile, 6000 of Taiwan’s community associations have been running community empowerment programs supported by the Council for Cultural Affairs that have helped many neighborhoods to rebuild so-called community cohesion. This research attempts to evaluate whether neighborhoods with facilities near housing and shorter travel distances within a neighborhood would promote stronger social interactions and form a better community attachment than neighborhoods that have various opportunities for residents to participate in either formal or informal social gatherings. After interviewing and surveying residents from 19 neighborhoods in Taipei’s Beitou District, and correlating the psychological sense of community with inner neighborhood’s daily travel distances and numbers of participatory activities held by community organizations under empowerment programs together with frequencies of regular individual visits and casual meetings, statistical evidence yielded that placing public facilities near residential locations is more effective than providing various programs for elevating a sense of community.

  3. Ni2P Makes Application of the PtRu Catalyst Much Stronger in Direct Methanol Fuel Cells.

    Science.gov (United States)

    Chang, Jinfa; Feng, Ligang; Liu, Changpeng; Xing, Wei

    2015-10-12

    PtRu is regarded as the best catalyst for direct methanol fuel cells, but the performance decay resulting from the loss of Ru seriously hinders commercial applications. Herein, we demonstrated that the presence of Ni2 P largely reduces Ru loss, which thus makes the application of PtRu much stronger in direct methanol fuel cells. Outstanding catalytic activity and stability were observed by cyclic voltammetry. Upon integrating the catalyst material into a practical direct methanol fuel cell, the highest maximum power density was achieved on the PtRu-Ni2P/C catalyst among the reference catalysts at different temperatures. A maximum power density of 69.9 mW cm(-2) at 30 °C was obtained on PtRu-Ni2P/C, which is even higher than the power density of the state-of-the-art commercial PtRu catalyst at 70 °C (63.1 mW cm(-2)). Moreover, decay in the performance resulting from Ru loss was greatly reduced owing to the presence of Ni2 P, which is indicative of very promising applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Nitrogen fertilization has a stronger effect on soil nitrogen-fixing bacterial communities than elevated atmospheric CO2.

    Science.gov (United States)

    Berthrong, Sean T; Yeager, Chris M; Gallegos-Graves, Laverne; Steven, Blaire; Eichorst, Stephanie A; Jackson, Robert B; Kuske, Cheryl R

    2014-05-01

    Biological nitrogen fixation is the primary supply of N to most ecosystems, yet there is considerable uncertainty about how N-fixing bacteria will respond to global change factors such as increasing atmospheric CO2 and N deposition. Using the nifH gene as a molecular marker, we studied how the community structure of N-fixing soil bacteria from temperate pine, aspen, and sweet gum stands and a brackish tidal marsh responded to multiyear elevated CO2 conditions. We also examined how N availability, specifically, N fertilization, interacted with elevated CO2 to affect these communities in the temperate pine forest. Based on data from Sanger sequencing and quantitative PCR, the soil nifH composition in the three forest systems was dominated by species in the Geobacteraceae and, to a lesser extent, Alphaproteobacteria. The N-fixing-bacterial-community structure was subtly altered after 10 or more years of elevated atmospheric CO2, and the observed shifts differed in each biome. In the pine forest, N fertilization had a stronger effect on nifH community structure than elevated CO2 and suppressed the diversity and abundance of N-fixing bacteria under elevated atmospheric CO2 conditions. These results indicate that N-fixing bacteria have complex, interacting responses that will be important for understanding ecosystem productivity in a changing climate.

  5. Aryl hydrocarbon receptor signaling modulates antiviral immune responses: ligand metabolism rather than chemical source is the stronger predictor of outcome.

    Science.gov (United States)

    Boule, Lisbeth A; Burke, Catherine G; Jin, Guang-Bi; Lawrence, B Paige

    2018-01-29

    The aryl hydrocarbon receptor (AHR) offers a compelling target to modulate the immune system. AHR agonists alter adaptive immune responses, but the consequences differ across studies. We report here the comparison of four agents representing different sources of AHR ligands in mice infected with influenza A virus (IAV): TCDD, prototype exogenous AHR agonist; PCB126, pollutant with documented human exposure; ITE, novel pharmaceutical; and FICZ, degradation product of tryptophan. All four compounds diminished virus-specific IgM levels and increased the proportion of regulatory T cells. TCDD, PCB126 and ITE, but not FICZ, reduced virus-specific IgG levels and CD8 + T cell responses. Similarly, ITE, PCB126, and TCDD reduced Th1 and Tfh cells, whereas FICZ increased their frequency. In Cyp1a1-deficient mice, all compounds, including FICZ, reduced the response to IAV. Conditional Ahr knockout mice revealed that all four compounds require AHR within hematopoietic cells. Thus, differences in the immune response to IAV likely reflect variances in quality, magnitude, and duration of AHR signaling. This indicates that binding affinity and metabolism may be stronger predictors of immune effects than a compound's source of origin, and that harnessing AHR will require finding a balance between dampening immune-mediated pathologies and maintaining sufficient host defenses against infection.

  6. Ionic versus nonionic contrast media

    International Nuclear Information System (INIS)

    Zylak, C.J.; Gafni, A.

    1988-01-01

    The efficacy and effectiveness of the nonionic contrast media have been established. Widespread usage has been hampered because of the approximate tenfold increase in cost compared with the ionic media. An economic evaluation considering costs and consequences of both interventions (ionic vs nonionic contrast media) was performed; it is a cost effectiveness (CEA) and a cost-benefit analysis (CBA) for the Canadian experience. The results of the CEA demonstrate a value per life-year saved within an acceptable range when compared with value for quality-adjusted life years for programs such as treatment of severe (diastolic≥ 105 mm Hg) and mild (diastolic 95-104 mm Hg) hypertension in men aged 40. The CBA showed a net cost to society when benefits were measured as future treatment costs saved plus productivity gained. However, if people are willing to pay a small amount for the comfort of the new intervention, this will result in a break-even situation

  7. Contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Bosmans, H.; Marchal, G.

    1996-01-01

    Despite many optimizations, the current limitations of plain MR angiography include: Saturation that impairs the visualization of veins and arteries with slow flow and spin-dephasing signal voids in locations with turbulent flow. Recently, the use of contrast agents has been proposed to cope with these remaining problems. Because of induced shortening of the T1 of the blood, saturation in the blood vessels is overcome. As a result, arteries and veins are visualized with the same signal intensity, which makes the technique less flow-dependent. In combination with short T1-weighted acquisitions, today CE MRA can be obtained while the patient is holding his breath. This last approach is most promising for abdominal applications since the respiratory motion can be frozen. As these acquisitions also use very short echo times, spin dephasing can be reduced. In conclusion, the use of contrast agents has greatly increased the clinical usefulness of MR angiography. (orig.) [de

  8. Minimum resolvable power contrast model

    Science.gov (United States)

    Qian, Shuai; Wang, Xia; Zhou, Jingjing

    2018-01-01

    Signal-to-noise ratio and MTF are important indexs to evaluate the performance of optical systems. However,whether they are used alone or joint assessment cannot intuitively describe the overall performance of the system. Therefore, an index is proposed to reflect the comprehensive system performance-Minimum Resolvable Radiation Performance Contrast (MRP) model. MRP is an evaluation model without human eyes. It starts from the radiance of the target and the background, transforms the target and background into the equivalent strips,and considers attenuation of the atmosphere, the optical imaging system, and the detector. Combining with the signal-to-noise ratio and the MTF, the Minimum Resolvable Radiation Performance Contrast is obtained. Finally the detection probability model of MRP is given.

  9. Effects of theophyline on contrast

    OpenAIRE

    A.R. Fatahiyan; B. Baqerii; A. Mohseni; A. Makhlouq

    2006-01-01

    Background and purpose: Contrast-induced nephropathy (CN) is one of the most common causes of iatrogenic acute renal failure. In fact CN is the third leading cause of new ARF in hospitalized patients. Radiocontrast-associated ARF is a significant problem in patients with cardiovascular disease. The risk factors for cardiovascular disease also predispose these patients to an increased risk of renal failure. Various strategies have been suggested for preventing CN. Since adenosine may play a ro...

  10. Which cue to ‘want’? Opioid stimulation of central amygdala makes goal-trackers show stronger goal-tracking, just as sign-trackers show stronger sign-tracking

    Science.gov (United States)

    DiFeliceantonio, Alexandra G.; Berridge, Kent C.

    2012-01-01

    Pavlovian cues that have been paired with reward can gain incentive salience. Drug addicts find drug cues motivationally attractive and binge eaters are attracted by food cues. But the level of incentive salience elicited by a cue re-encounter still varies across time and brain states. In an animal model, cues become attractive and ‘wanted’ in an ‘autoshaping’ paradigm, where different targets of incentive salience emerge for different individuals. Some individuals (sign-trackers) find a predictive discrete cue attractive while others find a reward contiguous and goal cue more attractive (location where reward arrives: goal-trackers). Here we assessed whether central amygdala mu opioid receptor stimulation enhances the phasic incentive salience of the goal-cue for goal-trackers during moments of predictive cue presence (expressed in both approach and consummatory behaviors to goal cue), just as it enhances the attractiveness of the predictive cue target for sign-trackers. Using detailed video analysis we measured the approaches, nibbles, sniffs, and bites directed at their preferred target for both sign-trackers and goal-trackers. We report that DAMGO microinjections in central amygdala made goal-trackers, like sign-trackers, show phasic increases in appetitive nibbles and sniffs directed at the goal-cue expressed selectively whenever the predictive cue was present. This indicates enhancement of incentive salience attributed by both goal trackers and sign-trackers, but attributed in different directions: each to their own target cue. For both phenotypes, amygdala opioid stimulation makes the individual’s prepotent cue into a stronger motivational magnet at phasic moments triggered by a CS that predicts the reward UCS. PMID:22391118

  11. Contrast detail phantom for SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Cabrejas, M.L. de; Arashiro, J G; Giannone, C. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Camuyrano, M; Nohara, G [Universidad de Buenos Aires, Buenos Aires (Argentina). Facultad Ciencias Exactas

    1996-06-01

    A new low variable contrast phantom for single photon emission computed tomography (SPECT) was constructed, tested and compared with other existing phantoms. It contains simulated cylindrical lesions of four different diameters (D{sub i}), embedded in a cylindrical scattering medium and a uniform section to evaluate tomographic uniformity. The concentration of tracer in the simulated lesions and the scattering medium (background) can be varied to simulate hot and cold lesions. Different applications of the phantom were tested, including determination of the minimum object contrast (OCm) necessary to detect lesions as a function of lesion size, lesion type (hot or cold) and acquisition and processing protocols by visual inspection. This parameter allows categorization of instruments comparing an `image quality index` (IQI). Preliminary comparison with the Britten contrast processing method showed that the detectable OCm was of the same order of magnitude, but the presented device seems more suitable for training and intercomparison purposes. The constructed phantom, of simple design, has proved to be useful for acquisition and processing condition evaluation, OCm estimation and external quality control. (author). 11 refs, 4 figs.

  12. Advancing High Contrast Adaptive Optics

    Science.gov (United States)

    Ammons, M.; Poyneer, L.; GPI Team

    2014-09-01

    A long-standing challenge has been to directly image faint extrasolar planets adjacent to their host suns, which may be ~1-10 million times brighter than the planet. Several extreme AO systems designed for high-contrast observations have been tested at this point, including SPHERE, Magellan AO, PALM-3000, Project 1640, NICI, and the Gemini Planet Imager (GPI, Macintosh et al. 2014). The GPI is the world's most advanced high-contrast adaptive optics system on an 8-meter telescope for detecting and characterizing planets outside of our solar system. GPI will detect a previously unstudied population of young analogs to the giant planets of our solar system and help determine how planetary systems form. GPI employs a 44x44 woofer-tweeter adaptive optics system with a Shack-Hartmann wavefront sensor operating at 1 kHz. The controller uses Fourier-based reconstruction and modal gains optimized from system telemetry (Poyneer et al. 2005, 2007). GPI has an apodized Lyot coronal graph to suppress diffraction and a near-infrared integral field spectrograph for obtaining planetary spectra. This paper discusses current performance limitations and presents the necessary instrumental modifications and sensitivity calculations for scenarios related to high-contrast observations of non-sidereal targets.

  13. Electrofluidic systems for contrast management

    Science.gov (United States)

    Rebello, Keith J.; Maranchi, Jeffrey P.; Tiffany, Jason E.; Brown, Christopher Y.; Maisano, Adam J.; Hagedon, Matthew A.; Heikenfeld, Jason C.

    2012-06-01

    Operating in dynamic lighting conditions and in greatly varying backgrounds is challenging. Current paints and state-ofthe- art passive adaptive coatings (e.g. photochromics) are not suitable for multi- environment situations. A semi-active, low power, skin is needed that can adapt its reflective properties based on the background environment to minimize contrast through the development and incorporation of suitable pigment materials. Electrofluidic skins are a reflective display technology for electronic ink and paper applications. The technology is similar to that in E Ink but makes use of MEMS based microfluidic structures, instead of simple black and white ink microcapsules dispersed in clear oil. Electrofluidic skin's low power operation and fast switching speeds (~20 ms) are an improvement over current state-ofthe- art contrast management technologies. We report on a microfluidic display which utilizes diffuse pigment dispersion inks to change the contrast of the underlying substrate from 5.8% to 100%. Voltage is applied and an electromechanical pressure is used to pull a pigment dispersion based ink from a hydrophobic coated reservoir into a hydrophobic coated surface channel. When no voltage is applied, the Young-Laplace pressure pushes the pigment dispersion ink back down into the reservoir. This allows the pixel to switch from the on and off state by balancing the two pressures. Taking a systems engineering approach from the beginning of development has enabled the technology to be integrated into larger systems.

  14. Stronger influence of maternal than paternal obesity on infant and early childhood body mass index: the Fels Longitudinal Study.

    Science.gov (United States)

    Linabery, A M; Nahhas, R W; Johnson, W; Choh, A C; Towne, B; Odegaard, A O; Czerwinski, S A; Demerath, E W

    2013-06-01

    Excessive early childhood adiposity is a prevalent and increasing concern in many parts of the world. Parental obesity is one of the several factors previously associated with infant and early childhood weight, length and adiposity. Parental obesity represents a surrogate marker of the complex interplay among genetic, epigenetic and shared environmental factors, and is potentially modifiable. The relative contributions of maternal and paternal body mass index (BMI) to infant and early childhood growth, as well as the timing of such effects, have not been firmly established. Utilizing serial infant measurements and growth curve modelling, this is the largest study to fully characterize and formally compare associations between maternal and paternal BMI and offspring growth across the entire infancy and early childhood period. Maternal obesity is a stronger determinant of offspring BMI than paternal obesity at birth and from 2 to 3 years of age, suggesting that prevention efforts focused particularly on maternal lifestyle and BMI may be important in reducing excess infant BMI. The observation that maternal BMI effects are not constant, but rather present at birth, wane and re-emerge during late infancy, suggests that there is a window of opportunity in early infancy when targeted interventions on children of obese mothers may be most effective. Parental obesity influences infant body size. To fully characterize their relative effects on infant adiposity, associations between maternal and paternal body mass index (BMI) category (normal: ≤25 kg m(-2) , overweight: 25 - obese: ≥30 kg m(-2) ) and infant BMI were compared in Fels Longitudinal Study participants. A median of 9 serial weight and length measures from birth to 3.5 years were obtained from 912 European American children born in 1928-2008. Using multivariable mixed effects regression, contributions of maternal vs. paternal BMI status to infant BMI growth curves were evaluated. Cubic spline models

  15. Density regulation in Northeast Atlantic fish populations: Density dependence is stronger in recruitment than in somatic growth.

    Science.gov (United States)

    Zimmermann, Fabian; Ricard, Daniel; Heino, Mikko

    2018-05-01

    Population regulation is a central concept in ecology, yet in many cases its presence and the underlying mechanisms are difficult to demonstrate. The current paradigm maintains that marine fish populations are predominantly regulated by density-dependent recruitment. While it is known that density-dependent somatic growth can be present too, its general importance remains unknown and most practical applications neglect it. This study aimed to close this gap by for the first time quantifying and comparing density dependence in growth and recruitment over a large set of fish populations. We fitted density-dependent models to time-series data on population size, recruitment and age-specific weight from commercially exploited fish populations in the Northeast Atlantic Ocean and the Baltic Sea. Data were standardized to enable a direct comparison within and among populations, and estimated parameters were used to quantify the impact of density regulation on population biomass. Statistically significant density dependence in recruitment was detected in a large proportion of populations (70%), whereas for density dependence in somatic growth the prevalence of density dependence depended heavily on the method (26% and 69%). Despite age-dependent variability, the density dependence in recruitment was consistently stronger among age groups and between alternative approaches that use weight-at-age or weight increments to assess growth. Estimates of density-dependent reduction in biomass underlined these results: 97% of populations with statistically significant parameters for growth and recruitment showed a larger impact of density-dependent recruitment on population biomass. The results reaffirm the importance of density-dependent recruitment in marine fishes, yet they also show that density dependence in somatic growth is not uncommon. Furthermore, the results are important from an applied perspective because density dependence in somatic growth affects productivity and

  16. Pasture v. standard dairy cream in high-fat diet-fed mice: improved metabolic outcomes and stronger intestinal barrier.

    Science.gov (United States)

    Benoit, Bérengère; Plaisancié, Pascale; Géloën, Alain; Estienne, Monique; Debard, Cyrille; Meugnier, Emmanuelle; Loizon, Emmanuelle; Daira, Patricia; Bodennec, Jacques; Cousin, Olivier; Vidal, Hubert; Laugerette, Fabienne; Michalski, Marie-Caroline

    2014-08-28

    Dairy products derived from the milk of cows fed in pastures are characterised by higher amounts of conjugated linoleic acid and α-linolenic acid (ALA), and several studies have shown their ability to reduce cardiovascular risk. However, their specific metabolic effects compared with standard dairy in a high-fat diet (HFD) context remain largely unknown; this is what we determined in the present study with a focus on the metabolic and intestinal parameters. The experimental animals were fed for 12 weeks a HFD containing 20 % fat in the form of a pasture dairy cream (PDC) or a standard dairy cream (SDC). Samples of plasma, liver, white adipose tissue, duodenum, jejunum and colon were analysed. The PDC mice, despite a higher food intake, exhibited lower fat mass, plasma and hepatic TAG concentrations, and inflammation in the adipose tissue than the SDC mice. Furthermore, they exhibited a higher expression of hepatic PPARα mRNA and adipose tissue uncoupling protein 2 mRNA, suggesting an enhanced oxidative activity of the tissues. These results might be explained, in part, by the higher amounts of ALA in the PDC diet and in the liver and adipose tissue of the PDC mice. Moreover, the PDC diet was found to increase the proportions of two strategic cell populations involved in the protective function of the intestinal epithelium, namely Paneth and goblet cells in the small intestine and colon, compared with the SDC diet. In conclusion, a PDC HFD leads to improved metabolic outcomes and to a stronger gut barrier compared with a SDC HFD. This may be due, at least in part, to the protective mechanisms induced by specific lipids.

  17. Stronger back muscles reduce the incidence of vertebral fractures: a prospective 10 year follow-up of postmenopausal women.

    Science.gov (United States)

    Sinaki, M; Itoi, E; Wahner, H W; Wollan, P; Gelzcer, R; Mullan, B P; Collins, D A; Hodgson, S F

    2002-06-01

    The long-term protective effect of stronger back muscles on the spine was determined in 50 healthy white postmenopausal women, aged 58-75 years, 8 years after they had completed a 2 year randomized, controlled trial. Twenty-seven subjects had performed progressive, resistive back-strengthening exercises for 2 years and 23 had served as controls. Bone mineral density, spine radiographs, back extensor strength, biochemical marker values, and level of physical activity were obtained for all subjects at baseline, 2 years, and 10 years. Mean back extensor strength (BES) in the back-exercise (BE) group was 39.4 kg at baseline, 66.8 kg at 2 years (after 2 years of prescribed exercises), and 32.9 kg at 10 years (8 years after cessation of the prescribed exercises). Mean BES in the control (C) group was 36.9 kg at baseline, 49.0 kg at 2 years, and 26.9 kg at 10 years. The difference between the two groups was still statistically significant at 10 year follow-up (p = 0.001). The difference in bone mineral density, which was not significant between the two groups at baseline and 2 year follow-up, was significant at 10 year follow-up (p = 0.0004). The incidence of vertebral compression fracture was 14 fractures in 322 vertebral bodies examined (4.3%) in the C group and 6 fractures in 378 vertebral bodies examined (1.6%) in the BE group (chi-square test, p = 0.0290). The relative risk for compression fracture was 2.7 times greater in the C group than in the BE group. To our knowledge, this is the first study reported in the literature demonstrating the long-term effect of strong back muscles on the reduction of vertebral fractures in estrogen-deficient women.

  18. Faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart related to cytosolic inorganic phosphate (Pi) accumulation.

    Science.gov (United States)

    Korzeniewski, Bernard

    2016-08-01

    A model of the cell bioenergetic system was used to compare the effect of oxidative phosphorylation (OXPHOS) deficiencies in a broad range of moderate ATP demand in skeletal muscle and heart. Computer simulations revealed that kinetic properties of the system are similar in both cases despite the much higher mitochondria content and "basic" OXPHOS activity in heart than in skeletal muscle, because of a much higher each-step activation (ESA) of OXPHOS in skeletal muscle than in heart. Large OXPHOS deficiencies lead in both tissues to a significant decrease in oxygen consumption (V̇o2) and phosphocreatine (PCr) and increase in cytosolic ADP, Pi, and H(+) The main difference between skeletal muscle and heart is a much higher cytosolic Pi concentration in healthy tissue and much higher cytosolic Pi accumulation (level) at low OXPHOS activities in the former, caused by a higher PCr level in healthy tissue (and higher total phosphate pool) and smaller Pi redistribution between cytosol and mitochondria at OXPHOS deficiency. This difference does not depend on ATP demand in a broad range. A much greater Pi increase and PCr decrease during rest-to-moderate work transition in skeletal muscle at OXPHOS deficiencies than at normal OXPHOS activity significantly slows down the V̇o2 on-kinetics. Because high cytosolic Pi concentrations cause fatigue in skeletal muscle and can compromise force generation in skeletal muscle and heart, this system property can contribute to the faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart. Shortly, skeletal muscle with large OXPHOS deficiencies becomes fatigued already during low/moderate exercise. Copyright © 2016 the American Physiological Society.

  19. Phase contrast STEM for thin samples: Integrated differential phase contrast.

    Science.gov (United States)

    Lazić, Ivan; Bosch, Eric G T; Lazar, Sorin

    2016-01-01

    It has been known since the 1970s that the movement of the center of mass (COM) of a convergent beam electron diffraction (CBED) pattern is linearly related to the (projected) electrical field in the sample. We re-derive a contrast transfer function (CTF) for a scanning transmission electron microscopy (STEM) imaging technique based on this movement from the point of view of image formation and continue by performing a two-dimensional integration on the two images based on the two components of the COM movement. The resulting integrated COM (iCOM) STEM technique yields a scalar image that is linear in the phase shift caused by the sample and therefore also in the local (projected) electrostatic potential field of a thin sample. We confirm that the differential phase contrast (DPC) STEM technique using a segmented detector with 4 quadrants (4Q) yields a good approximation for the COM movement. Performing a two-dimensional integration, just as for the COM, we obtain an integrated DPC (iDPC) image which is approximately linear in the phase of the sample. Beside deriving the CTFs of iCOM and iDPC, we clearly point out the objects of the two corresponding imaging techniques, and highlight the differences to objects corresponding to COM-, DPC-, and (HA) ADF-STEM. The theory is validated with simulations and we present first experimental results of the iDPC-STEM technique showing its capability for imaging both light and heavy elements with atomic resolution and a good signal to noise ratio (SNR). Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Radiographic contrast media, function and future reassessed

    International Nuclear Information System (INIS)

    Sovak, M.

    1988-01-01

    A brief review is given of the use of radiographic contrast media in cholecysto- and cholangiography, central nervous system imaging, urography and angiography. Other aspects briefly discussed are the use of large i.v. doses of contrast media for CT contrast enhancement and the design theory for improved water soluble contrast media. (U.K.)

  1. Stronger pack warnings predict quitting more than weaker ones: finding from the ITC Malaysia and Thailand surveys.

    Science.gov (United States)

    Fathelrahman, Ahmed I; Li, Lin; Borland, Ron; Yong, Hua-Hie; Omar, Maizurah; Awang, Rahmat; Sirirassamee, Buppha; Fong, Geoffrey T; Hammond, David

    2013-09-18

    mechanisms for influencing quitting regardless of warning strength. The larger and more informative Thai warnings were associated with higher levels of reactions predictive of quitting and stronger associations with subsequent quitting, demonstrating their greater potency.

  2. Females have stronger neurogenic response than males after non-specific nasal challenge in patients with seasonal allergic rhinitis.

    Science.gov (United States)

    Tomljenovic, Dejan; Baudoin, Tomislav; Megla, Zeljka Bukovec; Geber, Goran; Scadding, Glenis; Kalogjera, Livije

    2018-07-01

    Epidemiological studies show female predominance in the prevalence of non- allergic rhinitis (NAR) and local allergic rhinitis (LAR). Experimental studies show female patients with allergic rhinitis (AR) demonstrate higher levels of sensitivity to irritants and airway hyperresponsiveness than males. Bronchial asthma shows female predominance in post-puberty patients, and gender interaction with severe asthma endotypes. Fibromyalgia, chronic fatigue syndrome, migraine and chronic cough, syndromes, which are commonly related to neurokinin substance P (SP) in the literature, also show strong female predominance. Studies have demonstrated that sex hormones, primarily oestrogens, affect mast cell activation. Mast cell proteases can amplify neurogenic inflammatory responses including the release of SP. Based on human epidemiological data and animal experimental data we hypothesized that female patients have different interaction between mast cell activation and neurogenic inflammation, i.e. substance P release, resulting in a different nasal symptom profile. To test the hypothesis we performed allergen and non-specific nasal challenges in patients with seasonal allergic rhinitis (SAR) out of season and looked for gender differences in subjective and objective responses. The interaction between subjective and objective reactivity was evaluated through the comparison of subjective symptom scores, concentrations of neurokinin substance P (SP) and cellular markers in nasal lavages after low doses of nasal allergen challenges. Female allergic subjects tended to have higher substance P (SP) concentrations both before and after non-specific challenges. The difference between post-allergen and post - hypertonic saline (HTS) challenge was highly significant in female patients (p = 0.001), while insignificant in male subjects (p = 0.14). Female patients had significantly stronger burning sensation after HTS challenge than male. These data indicate difference in the

  3. F247. INTERNALIZED STIGMA HAS A STRONGER RELATIONSHIP WITH INTRINSIC MOTIVATION COMPARED TO AMOTIVATION IN EARLY PHASE AND PROLONGED SCHIZOPHRENIA

    Science.gov (United States)

    Firmin, Ruth; Luther, Lauren; Lysaker, Paul; Vohs, Jennifer

    2018-01-01

    analyses indicated that, controlling for amotivation, internalized stigma predicted intrinsic motivation in both the prolonged sample (R2=0.09, F(1,64) =6.18, p=0.02) and the early phase schizophrenia sample (R2=0.23, F(1,37)=10.98, p=.00). Discussion Results suggest internalized stigma has a stronger relationship with intrinsic motivation separate from, and above and beyond, its association with amotivation. Findings support models of intrinsic and amotivation being distinct domains. Links between internalized stigma and motivation appear to emerge and persist from the early stages of schizophrenia, suggesting that targeting stigma in early intervention services may help to improve intrinsic motivation in people with schizophrenia.

  4. Ultrasound contrast agents: an overview.

    Science.gov (United States)

    Cosgrove, David

    2006-12-01

    With the introduction of microbubble contrast agents, diagnostic ultrasound has entered a new era that allows the dynamic detection of tissue flow of both the macro and microvasculature. Underpinning this development is the fact that gases are compressible, and thus the microbubbles expand and contract in the alternating pressure waves of the ultrasound beam, while tissue is almost incompressible. Special software using multiple pulse sequences separates these signals from those of tissue and displays them as an overlay or on a split screen. This can be done at low acoustic pressures (MIdeveloped for myocardial perfusion. In radiology, the most important application is the liver, especially for focal disease. The approach parallels that of dynamic CT or MRI but ultrasound has the advantages of high spatial and temporal resolution. Thus, small lesions that can be indeterminate on CT can often be studied with ultrasound, and situations where the flow is very rapid (e.g., focal nodular hyperplasia where the first few seconds of arterial perfusion may be critical to making the diagnosis) are readily studied. Microbubbles linger in the extensive sinusoidal space of normal liver for several minutes whereas they wash out rapidly from metastases, which have a low vascular volume and thus appear as filling defects. The method has been shown to be as sensitive as three-phase CT. Microbubbles have clinical uses in many other applications where knowledge of the microcirculation is important (the macrocirculation can usually be assessed adequately using conventional Doppler though there are a few important situations where the signal boost given by microbubbles is useful, e.g., transcranial Doppler for evaluating vasospasm after subarachnoid haemorrhage). An important situation where demonstrating tissue devitalisation is important is in interstitial ablation of focal liver lesions: using microbubble contrast agents at the end of a procedure allows immediate evaluation of the

  5. Clinical applications of contrast echocardiography

    International Nuclear Information System (INIS)

    Jorge, Leon Galindo

    2005-01-01

    The echocardiography is the technique more used for the diagnosis and pursuit of the cardiovascular illnesses; therefore, their diagnostic precision has acquired a vital importance in the handling of the patients with cardiovascular pathologies. However, with relative frequency, the diagnostic capacity of the echocardiography exam is diminished by limitations of the acoustic window, mainly in-patient with obesity, lung illnesses and alterations of the thoracic wall. This can be obviated with the use of the intra-esophagus echocardiography, although this it is a procedure semi-invasive and not very practical of carrying out in all the patients with problems of acoustic window. In this article the clinical applications are revised more common of the contrast echocardiography

  6. Ultrasound contrast agents: An overview

    International Nuclear Information System (INIS)

    Cosgrove, David

    2006-01-01

    With the introduction of microbubble contrast agents, diagnostic ultrasound has entered a new era that allows the dynamic detection of tissue flow of both the macro and microvasculature. Underpinning this development is the fact that gases are compressible, and thus the microbubbles expand and contract in the alternating pressure waves of the ultrasound beam, while tissue is almost incompressible. Special software using multiple pulse sequences separates these signals from those of tissue and displays them as an overlay or on a split screen. This can be done at low acoustic pressures (MI < 0.3) so that the microbubbles are not destroyed and scanning can continue in real time. The clinical roles of contrast enhanced ultrasound scanning are expanding rapidly. They are established in echocardiography to improve endocardial border detection and are being developed for myocardial perfusion. In radiology, the most important application is the liver, especially for focal disease. The approach parallels that of dynamic CT or MRI but ultrasound has the advantages of high spatial and temporal resolution. Thus, small lesions that can be indeterminate on CT can often be studied with ultrasound, and situations where the flow is very rapid (e.g., focal nodular hyperplasia where the first few seconds of arterial perfusion may be critical to making the diagnosis) are readily studied. Microbubbles linger in the extensive sinusoidal space of normal liver for several minutes whereas they wash out rapidly from metastases, which have a low vascular volume and thus appear as filling defects. The method has been shown to be as sensitive as three-phase CT. Microbubbles have clinical uses in many other applications where knowledge of the microcirculation is important (the macrocirculation can usually be assessed adequately using conventional Doppler though there are a few important situations where the signal boost given by microbubbles is useful, e.g., transcranial Doppler for evaluating

  7. Phase contrast STEM for thin samples: Integrated differential phase contrast

    International Nuclear Information System (INIS)

    Lazić, Ivan; Bosch, Eric G.T.; Lazar, Sorin

    2016-01-01

    It has been known since the 1970s that the movement of the center of mass (COM) of a convergent beam electron diffraction (CBED) pattern is linearly related to the (projected) electrical field in the sample. We re-derive a contrast transfer function (CTF) for a scanning transmission electron microscopy (STEM) imaging technique based on this movement from the point of view of image formation and continue by performing a two-dimensional integration on the two images based on the two components of the COM movement. The resulting integrated COM (iCOM) STEM technique yields a scalar image that is linear in the phase shift caused by the sample and therefore also in the local (projected) electrostatic potential field of a thin sample. We confirm that the differential phase contrast (DPC) STEM technique using a segmented detector with 4 quadrants (4Q) yields a good approximation for the COM movement. Performing a two-dimensional integration, just as for the COM, we obtain an integrated DPC (iDPC) image which is approximately linear in the phase of the sample. Beside deriving the CTFs of iCOM and iDPC, we clearly point out the objects of the two corresponding imaging techniques, and highlight the differences to objects corresponding to COM-, DPC-, and (HA) ADF-STEM. The theory is validated with simulations and we present first experimental results of the iDPC-STEM technique showing its capability for imaging both light and heavy elements with atomic resolution and a good signal to noise ratio (SNR). - Highlights: • First DPC-based atomic resolution images of potential and charge density are obtained. • This is enabled by integration and differentiation of 2D DPC signals, respectively. • Integrated DPC (iDPC) based on 4 quadrant imaging is compared to iCOM imaging. • Noise analysis and comparison with standard STEM imaging modes is provided. • iDPC allows direct imaging of light (C, N, O …) and heavy (Ga, Au …) atoms together.

  8. Phase contrast STEM for thin samples: Integrated differential phase contrast

    Energy Technology Data Exchange (ETDEWEB)

    Lazić, Ivan, E-mail: ivan.lazic@fei.com; Bosch, Eric G.T.; Lazar, Sorin

    2016-01-15

    It has been known since the 1970s that the movement of the center of mass (COM) of a convergent beam electron diffraction (CBED) pattern is linearly related to the (projected) electrical field in the sample. We re-derive a contrast transfer function (CTF) for a scanning transmission electron microscopy (STEM) imaging technique based on this movement from the point of view of image formation and continue by performing a two-dimensional integration on the two images based on the two components of the COM movement. The resulting integrated COM (iCOM) STEM technique yields a scalar image that is linear in the phase shift caused by the sample and therefore also in the local (projected) electrostatic potential field of a thin sample. We confirm that the differential phase contrast (DPC) STEM technique using a segmented detector with 4 quadrants (4Q) yields a good approximation for the COM movement. Performing a two-dimensional integration, just as for the COM, we obtain an integrated DPC (iDPC) image which is approximately linear in the phase of the sample. Beside deriving the CTFs of iCOM and iDPC, we clearly point out the objects of the two corresponding imaging techniques, and highlight the differences to objects corresponding to COM-, DPC-, and (HA) ADF-STEM. The theory is validated with simulations and we present first experimental results of the iDPC-STEM technique showing its capability for imaging both light and heavy elements with atomic resolution and a good signal to noise ratio (SNR). - Highlights: • First DPC-based atomic resolution images of potential and charge density are obtained. • This is enabled by integration and differentiation of 2D DPC signals, respectively. • Integrated DPC (iDPC) based on 4 quadrant imaging is compared to iCOM imaging. • Noise analysis and comparison with standard STEM imaging modes is provided. • iDPC allows direct imaging of light (C, N, O …) and heavy (Ga, Au …) atoms together.

  9. Water content differences have stronger effects than plant functional groups on soil bacteria in a steppe ecosystem.

    Directory of Open Access Journals (Sweden)

    Ximei Zhang

    Full Text Available Many investigations across natural and artificial plant diversity gradients have reported that both soil physicochemical factors and plant community composition affect soil microbial communities. To test the effect of plant diversity loss on soil bacterial communities, we conducted a five-year plant functional group removal experiment in a steppe ecosystem in Inner Mongolia (China. We found that the number and composition type of plant functional groups had no effect on bacterial diversity and community composition, or on the relative abundance of major taxa. In contrast, bacterial community patterns were significantly structured by soil water content differences among plots. Our results support researches that suggest that water availability is the key factor structuring soil bacterial communities in this semi-arid ecosystem.

  10. Experimental validation of the Wigner distributions theory of phase-contrast imaging

    International Nuclear Information System (INIS)

    Donnelly, Edwin F.; Price, Ronald R.; Pickens, David R.

    2005-01-01

    Recently, a new theory of phase-contrast imaging has been proposed by Wu and Liu [Med. Phys. 31, 2378-2384 (2004)]. This theory, based upon Wigner distributions, provides a much stronger foundation for the evaluation of phase-contrast imaging systems than did the prior theories based upon Fresnel-Kirchhoff diffraction theory. In this paper, we compare results of measurements made in our laboratory of phase contrast for different geometries and tube voltages to the predictions of the Wu and Liu model. In our previous publications, we have used an empirical measurement (the edge enhancement index) to parametrize the degree of phase-contrast effects in an image. While the Wu and Liu model itself does not predict image contrast, it does measure the degree of phase contrast that the system can image for a given spatial frequency. We have found that our previously published experimental results relating phase-contrast effects to geometry and x-ray tube voltage are consistent with the predictions of the Wu and Liu model

  11. Evaluation of contrast in duplicated radiographs

    International Nuclear Information System (INIS)

    Thunthy, K.H.; Weinberg, R.

    1982-01-01

    This investigation evaluated changes in the contrast of duplicated radiographs made at different ultraviolet light exposures. Increasing ultraviolet light exposure had different effects on the duplicates of originals of different background densities. When correctly exposed, a duplicate radiograph enhanced contrast. When originals had the same contrast but different background densities, their duplicates did not have the same contrast. It was not possible to duplicate accurately all the different contrasts measured on an original. It was possible, however, to produce duplicates with all contrasts greater than those of the original

  12. Brute force absorption contrast microtomography

    Science.gov (United States)

    Davis, Graham R.; Mills, David

    2014-09-01

    In laboratory X-ray microtomography (XMT) systems, the signal-to-noise ratio (SNR) is typically determined by the X-ray exposure due to the low flux associated with microfocus X-ray tubes. As the exposure time is increased, the SNR improves up to a point where other sources of variability dominate, such as differences in the sensitivities of adjacent X-ray detector elements. Linear time-delay integration (TDI) readout averages out detector sensitivities on the critical horizontal direction and equiangular TDI also averages out the X-ray field. This allows the SNR to be increased further with increasing exposure. This has been used in dentistry to great effect, allowing subtle variations in dentine mineralisation to be visualised in 3 dimensions. It has also been used to detect ink in ancient parchments that are too damaged to physically unroll. If sufficient contrast between the ink and parchment exists, it is possible to virtually unroll the tomographic image of the scroll in order that the text can be read. Following on from this work, a feasibility test was carried out to determine if it might be possible to recover images from decaying film reels. A successful attempt was made to re-create a short film sequence from a rolled length of 16mm film using XMT. However, the "brute force" method of scaling this up to allow an entire film reel to be imaged presents a significant challenge.

  13. Integral equations with contrasting kernels

    Directory of Open Access Journals (Sweden)

    Theodore Burton

    2008-01-01

    Full Text Available In this paper we study integral equations of the form $x(t=a(t-\\int^t_0 C(t,sx(sds$ with sharply contrasting kernels typified by $C^*(t,s=\\ln (e+(t-s$ and $D^*(t,s=[1+(t-s]^{-1}$. The kernel assigns a weight to $x(s$ and these kernels have exactly opposite effects of weighting. Each type is well represented in the literature. Our first project is to show that for $a\\in L^2[0,\\infty$, then solutions are largely indistinguishable regardless of which kernel is used. This is a surprise and it leads us to study the essential differences. In fact, those differences become large as the magnitude of $a(t$ increases. The form of the kernel alone projects necessary conditions concerning the magnitude of $a(t$ which could result in bounded solutions. Thus, the next project is to determine how close we can come to proving that the necessary conditions are also sufficient. The third project is to show that solutions will be bounded for given conditions on $C$ regardless of whether $a$ is chosen large or small; this is important in real-world problems since we would like to have $a(t$ as the sum of a bounded, but badly behaved function, and a large well behaved function.

  14. Responding to the Challenge of Providing Stronger Research Base for Teacher Education: Research Discourses in the Norwegian National Research School for Teacher Education

    Science.gov (United States)

    Østern, Anna-Lena

    2016-01-01

    Background and purpose: The purpose of this article is to shed light on how the research projects of 140 PhD candidates in the National Research School for Teacher Education in Norway (NAFOL) respond to the challenges faced by Norwegian teacher education regarding the demand for higher competence and a stronger research base. The concept of NAFOL…

  15. Individual and age-related variation in chromatic contrast adaptation

    Science.gov (United States)

    Elliott, Sarah L.; Werner, John S.; Webster, Michael A.

    2012-01-01

    Precortical color channels are tuned primarily to the LvsM (stimulation of L and M cones varied, but S cone stimulation held constant) or SvsLM (stimulation of S cones varied, but L and M cone stimulation held constant) cone-opponent (cardinal) axes, but appear elaborated in the cortex to form higher-order mechanisms tuned to both cardinal and intermediate directions. One source of evidence for these higher-order mechanisms has been the selectivity of color contrast adaptation for noncardinal directions, yet the degree of this selectivity has varied widely across the small sample of observers tested in previous studies. This study explored the possible bases for this variation, and in particular tested whether it reflected age-related changes in the distribution or tuning of color mechanisms. Observers included 15 younger (18–22 years of age) and 15 older individuals (66–82), who adapted to temporal modulations along one of four chromatic axes (two cardinal and two intermediate axes) and then matched the hue and contrast of test stimuli lying along eight different directions in the equiluminant plane. All observers exhibited aftereffects that were selective for both the cardinal and intermediate directions, although selectivity was weaker for the intermediate axes. The degree of selectivity increased with the magnitude of adaptation for all axes, and thus adaptation strength alone may account for much of the variance in selectivity among observers. Older observers showed a stronger magnitude of adaptation thus, surprisingly, more conspicuous evidence for higher-order mechanisms. For both age groups the aftereffects were well predicted by response changes in chromatic channels with linear spectral sensitivities, and there was no evidence for weakened channel tuning with aging. The results suggest that higher-order mechanisms may become more exposed in observers or conditions in which the strength of adaptation is greater, and that both chromatic contrast

  16. Bioactive leptin is stronger related to parameters of fat mass and distribution than conventionally measured leptin: Findings from a longitudinal study in obese children participating in a lifestyle intervention.

    Science.gov (United States)

    Niklowitz, Petra; Rothermel, Juliane; Lass, Nina; Barth, Andre; Reinehr, Thomas

    2018-05-01

    This study analyzed the relationships between bioactive leptin, conventionally measured leptin, and parameters of fat mass and distribution in obese children before and after weight reduction. We determined bioactive leptin (bioLep), conventional measured leptin (conLep), weight, height, body fat based on skinfold measurements and bioimpedance analyses, waist circumference (wc), and pubertal stage in 88 obese children participating in a lifestyle intervention at baseline and one year later. We identified no child with homozygous or heterozygous status for bioinactive leptin mutations. The baseline associations between bioLep and BMI (r = 0.53), BMI-SDS (r = 0.48), body fat (bioimpedance: r = 0.61, skinfold thickness: r = 0.49), wc (r = 0.42), and waist to height ratio (whr) (r = 0.39) were stronger than the associations between conLep and BMI (r = 0.50), BMI-SDS (r = 0.44), body fat (bioimpedance: r = 0.57, skinfold thickness: r = 0.41), wc (r = 0.41), and whr (r = 0.37). The changes of bioLep were stronger related to changes of BMI-SDS (r = 0.54), body fat (bioimpedance r = 0.59, skinfold thickness: r = 0.37), wc (r = 0.22), and whr (r = 0.21) than the associations between changes of conLep and changes of BMI-SDS (r = 0.48), body fat (bioimpedance: r = 0.56, skinfold thickness: r = 0.43), wc (r = 0.20), and whr (r = 0.20). The same findings were observed in multiple linear regression analyses adjusted to multiple confounders. In contrast to changes of conLep (r = 0.22), the changes of bioLep during intervention were not related to weight regain after the end of intervention. BioLep concentrations did not differ between prepubertal girls and boys, but were higher in pubertal girls compared to pubertal boys (p = 0.031). Bioactive leptin was stronger related to fat mass and distribution compared to conventionally measured leptin. Copyright © 2018 Elsevier B.V. All rights

  17. Contrast enhanced CT of spinal cord angioma

    International Nuclear Information System (INIS)

    Nakamura, Takahiko; Ebitani, Tsutomu; Honma, Takao; Sofue, Muroto; Nakamura, Shigeru

    1982-01-01

    Contrast enhanced CT on 6 patients with spinal cord angioma showed enhancement in 2 of them. The conditions to produce contrast enhancement were the window width of 100 - 200, and the window level of 0 - 50. In spinal cord angioma, contrast enhanced CT is presently only an adjunct to angiography and myelography. Nevertheless, contrast enhanced CT is useful in the screening test for spinal cord angioma, in the patients who are nonindicated to angiography, and in the postoperative follow-up. (Ueda, J.)

  18. Quantitative Differences Between the First and Second Injection of Contrast Agent in Contrast-Enhanced Ultrasonography of Feline Kidneys and Spleen.

    Science.gov (United States)

    Stock, Emmelie; Vanderperren, Katrien; Haers, Hendrik; Duchateau, Luc; Hesta, Myriam; Saunders, Jimmy H

    2017-02-01

    Contrast-enhanced ultrasound is a valuable and safe technique for the evaluation of organ perfusion. Repeated injections of ultrasound contrast agent are often administered during the same imaging session. However, it remains unclear if quantitative differences are present between the consecutive microbubble injections. Therefore, the first and second injection of contrast agent for the left renal cortex, renal medulla and the splenic parenchyma in healthy cats were compared. A lower peak intensity and area under the curve were observed for the first injection of contrast agent in the feline kidney, both for the renal cortex and medulla, and spleen. Moreover, for the renal cortex, the time-intensity curve was steeper after the second injection. Findings from the present study demonstrate that a second injection of contrast agent provides stronger enhancement. The exact mechanism behind our findings remains unclear; however, saturation of the lung macrophages is believed to play an important role. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  19. Using Contrastive Rhetoric in the ESL Classroom

    Science.gov (United States)

    Quinn, Janet M.

    2012-01-01

    Contrastive rhetoric studies the writing of second language learners to understand how it is affected by their first language and culture. The field of contrastive rhetoric is as multidimensional as second language writing is complex. It draws on the work of contrastive analysis, anthropology, linguistics, pedagogy, culture studies, translation…

  20. Contrast media are helpful in computerized tomography

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    Contrast media very often can decisively improve the image contrasts, and thus contribute to making the differential diagnosis more specific. This survey of a symposium on the current status of CT refers particularly to the lectures that discussed the use of contrast media for neuroradiology, and the risks involved. (orig.) [de

  1. What doesn't kill you might make you stronger: functional basis for variation in body armour.

    Science.gov (United States)

    Broeckhoven, Chris; Diedericks, Genevieve; Mouton, P le Fras N

    2015-09-01

    1. Predation has been proposed to be a selective agent in the evolution of morphological antipredator strategies in prey. Among vertebrates, one of the morphological traits that evolved multiple times is body armour, including carapaces, thickened keratinized scales and plates of dermal bone. 2. It has been generally assumed that body armour provides protection against a predatory attack; yet, few explicit tests of the hypothesis exist. Cordylidae, a relatively small family of southern African lizards, show considerable variation in the degree of body armour. Hence, this family provides an opportunity to test the hypothesis that body armour serves as protection against predators. 3. Experiments were conducted to test whether the bite forces of four species of mammalian predators were high enough to penetrate the skins of Karusasaurus polyzonus, Namazonurus peersi, Cordylus cordylus and Cordylus macropholis, as well as those of Ouroborus cataphractus individuals originating from three localities that differed in their predator diversity. Furthermore, histological techniques were used to test whether variation in skin toughness was associated with concomitant changes in the degree of epidermal (i.e. β-keratin) and dermal (i.e. osteoderm) armour. 4. The skin toughness values for four out of five cordylid lizards tested in this study were well below the bite forces of the mammalian predators. In contrast, the thick osteoderms in the dermis of O. cataphractus can withstand bites from several mongoose species. However, the significant variation in body armour that is present between the three populations of O. cataphractus does not seem to be related to predator diversity. 5. It is concluded that body armour can serve as protection against predation in O. cataphractus, but that alternative selection pressures, such as thermoregulation or predation by snakes, presumably underlie variation in defensive morphology in the other cordylid lizards. © 2015 The Authors. Journal

  2. Stronger efferent suppression of cochlear neural potentials by contralateral acoustic stimulation in awake than in anesthetized chinchilla

    Directory of Open Access Journals (Sweden)

    Cristian eAedo

    2015-03-01

    Full Text Available There are two types of sensory cells in the mammalian cochlea, inner hair cells, which make synaptic contact with auditory-nerve afferent fibers, and outer hair cells that are innervated by crossed and uncrossed medial olivocochlear (MOC efferent fibers. Contralateral acoustic stimulation activates the uncrossed efferent MOC fibers reducing cochlear neural responses, thus modifying the input to the central auditory system. The chinchilla, among all studied mammals, displays the lowest percentage of uncrossed MOC fibers raising questions about the strength and frequency distribution of the contralateral-sound effect in this species. On the other hand, MOC effects on cochlear sensitivity have been mainly studied in anesthetized animals and since the MOC-neuron activity depends on the level of anesthesia, it is important to assess the influence of anesthesia in the strength of efferent effects. Seven adult chinchillas (Chinchilla laniger were chronically implanted with round-window electrodes in both cochleae. We compared the effect of contralateral sound in awake and anesthetized condition. Compound action potentials (CAP and cochlear microphonics (CM were measured in the ipsilateral cochlea in response to tones in absence and presence of contralateral sound. Control measurements performed after middle-ear muscles section in one animal discarded any possible middle-ear reflex activation. Contralateral sound produced CAP amplitude reductions in all chinchillas, with suppression effects greater by about 1-3 dB in awake than in anesthetized animals. In contrast, CM amplitude increases of up to 1.9 dB were found in only three awake chinchillas. In both conditions the strongest efferent effects were produced by contralateral tones at frequencies equal or close to those of ipsilateral tones. Contralateral CAP suppressions for 1-6 kHz ipsilateral tones corresponded to a span of uncrossed MOC fiber innervation reaching at least the central third of the

  3. Stronger efferent suppression of cochlear neural potentials by contralateral acoustic stimulation in awake than in anesthetized chinchilla.

    Science.gov (United States)

    Aedo, Cristian; Tapia, Eduardo; Pavez, Elizabeth; Elgueda, Diego; Delano, Paul H; Robles, Luis

    2015-01-01

    There are two types of sensory cells in the mammalian cochlea, inner hair cells, which make synaptic contact with auditory-nerve afferent fibers, and outer hair cells that are innervated by crossed and uncrossed medial olivocochlear (MOC) efferent fibers. Contralateral acoustic stimulation activates the uncrossed efferent MOC fibers reducing cochlear neural responses, thus modifying the input to the central auditory system. The chinchilla, among all studied mammals, displays the lowest percentage of uncrossed MOC fibers raising questions about the strength and frequency distribution of the contralateral-sound effect in this species. On the other hand, MOC effects on cochlear sensitivity have been mainly studied in anesthetized animals and since the MOC-neuron activity depends on the level of anesthesia, it is important to assess the influence of anesthesia in the strength of efferent effects. Seven adult chinchillas (Chinchilla laniger) were chronically implanted with round-window electrodes in both cochleae. We compared the effect of contralateral sound in awake and anesthetized condition. Compound action potentials (CAP) and cochlear microphonics (CM) were measured in the ipsilateral cochlea in response to tones in absence and presence of contralateral sound. Control measurements performed after middle-ear muscles section in one animal discarded any possible middle-ear reflex activation. Contralateral sound produced CAP amplitude reductions in all chinchillas, with suppression effects greater by about 1-3 dB in awake than in anesthetized animals. In contrast, CM amplitude increases of up to 1.9 dB were found in only three awake chinchillas. In both conditions the strongest efferent effects were produced by contralateral tones at frequencies equal or close to those of ipsilateral tones. Contralateral CAP suppressions for 1-6 kHz ipsilateral tones corresponded to a span of uncrossed MOC fiber innervation reaching at least the central third of the chinchilla cochlea.

  4. Effect of intensifying screens to subject contrast

    International Nuclear Information System (INIS)

    Lee, In Ja; Huh, Joon; Kang, Hong Seok; Yoon, Chul Ho

    1990-01-01

    It is an experimental report about object contrast according to the Kinds of screen and obtained results as follows ; 1. In the same object radiography, use acquired the difference of the object contrast between LT-II(CaWO 4 system) and G4(Gd system) screens. 2. object contrast more decreased in Gd system screen than CaWO 4 and object contrast controlled by X-ray tube voltage. 3. The difference of object contrast seen clearly in 80 kVp

  5. Contrast Enhanced US in the Abdomen

    International Nuclear Information System (INIS)

    Chung, Yong Eun; Kim, Ki Whang

    2012-01-01

    Contrast enhanced ultrasound, which was introduced in 1996, has been widely used in Europe and Eastern Asia. Ultrasound contrast agent can be classified as first generation and second generation, depending on the gas within the microbubble. With the first generation contrast agent, the high MI technique was used, and only intermittent scanning was possible due to destruction of the microbubble during scanning. Use of the second generation contrast agent with the low MI technique makes continuous scanning possible. Contrast enhanced US can be used in detection and differentiation of focal liver lesions. It is also helpful for monitoring of radiofrequency ablation and for targeting of US guided biopsy. Currently, because morphologic criteria alone may not reflect the response of the tumor to treatment, new criteria are needed for treatment evaluation after administration of anti-angiogenic agents. Contrast enhanced US could provide quantitative markers for evaluation of the response to treatment via use of dynamic contrast enhanced US. Due to cost-effectiveness, contrast enhanced US is not yet widely used in Korea; however, considering recent issues regarding contrast agent related adverse reaction, such as contrast induced nephropathy and nephrogenic systemic fibrosis, and radiation exposure, contrast enhanced US might be more widely used in Korea, as an alternative imaging modality in the future.

  6. MRI and CT contrast media extravasation

    Science.gov (United States)

    Heshmatzadeh Behzadi, Ashkan; Farooq, Zerwa; Newhouse, Jeffery H.; Prince, Martin R.

    2018-01-01

    Abstract Background: This systematic review combines data from multiple papers on contrast media extravasation to identify factors contributing to increased extravasation risk. Methods: Data were extracted from 17 papers reporting 2191 extravasations in 1,104,872 patients (0.2%) undergoing computed tomography (CT) or magnetic resonance imaging (MRI). Results: Extravasation rates were 0.045% for gadolinium-based contrast agents (GBCA) and nearly 6-fold higher, 0.26% for iodinated contrast agents. Factors associated with increased contrast media extravasations included: older age, female gender, using an existing intravenous (IV) instead of placing a new IV in radiology, in-patient status, use of automated power injection, high injection rates, catheter location, and failing to warm up the more viscous contrast media to body temperature. Conclusion: Contrast media extravasation is infrequent but nearly 6 times less frequent with GBCA for MRI compared with iodinated contrast used in CT. PMID:29489663

  7. The effect of transcranial direct current stimulation on contrast sensitivity and visual evoked potential amplitude in adults with amblyopia

    OpenAIRE

    Ding, Zhaofeng; Li, Jinrong; Spiegel, Daniel P.; Chen, Zidong; Chan, Lily; Luo, Guangwei; Yuan, Junpeng; Deng, Daming; Yu, Minbin; Thompson, Benjamin

    2016-01-01

    Amblyopia is a neurodevelopmental disorder of vision that occurs when the visual cortex receives decorrelated inputs from the two eyes during an early critical period of development. Amblyopic eyes are subject to suppression from the fellow eye, generate weaker visual evoked potentials (VEPs) than fellow eyes and have multiple visual deficits including impairments in visual acuity and contrast sensitivity. Primate models and human psychophysics indicate that stronger suppression is associated...

  8. Flash Infrared Thermography Contrast Data Analysis Technique

    Science.gov (United States)

    Koshti, Ajay

    2014-01-01

    This paper provides information on an IR Contrast technique that involves extracting normalized contrast versus time evolutions from the flash thermography inspection infrared video data. The analysis calculates thermal measurement features from the contrast evolution. In addition, simulation of the contrast evolution is achieved through calibration on measured contrast evolutions from many flat-bottom holes in the subject material. The measurement features and the contrast simulation are used to evaluate flash thermography data in order to characterize delamination-like anomalies. The thermal measurement features relate to the anomaly characteristics. The contrast evolution simulation is matched to the measured contrast evolution over an anomaly to provide an assessment of the anomaly depth and width which correspond to the depth and diameter of the equivalent flat-bottom hole (EFBH) similar to that used as input to the simulation. A similar analysis, in terms of diameter and depth of an equivalent uniform gap (EUG) providing a best match with the measured contrast evolution, is also provided. An edge detection technique called the half-max is used to measure width and length of the anomaly. Results of the half-max width and the EFBH/EUG diameter are compared to evaluate the anomaly. The information provided here is geared towards explaining the IR Contrast technique. Results from a limited amount of validation data on reinforced carbon-carbon (RCC) hardware are included in this paper.

  9. Using social capital to construct a conceptual International Classification of Functioning, Disability, and Health Children and Youth version-based framework for stronger inclusive education policies in Europe.

    Science.gov (United States)

    Maxwell, Gregor; Koutsogeorgou, Eleni

    2012-02-01

    Inclusive education is part of social inclusion; therefore, social capital can be linked to an inclusive education policy and practice. This association is explored in this article, and a practical measure is proposed. Specifically, the World Health Organization's International Classification of Functioning, Disability and Health Children and Youth Version (ICF-CY) is proposed as the link between social capital and inclusive education. By mapping participation and trust indicators of social capital to the ICF-CY and by using the Matrix to Analyse Functioning in Education Systems (MAFES) to analyze the functioning of inclusive education policies and systems, a measure for stronger inclusive education policies is proposed. Such a tool can be used for policy planning and monitoring to ensure better inclusive education environments. In conclusion, combining enhanced social capital linked to stronger inclusive education policies, by using the ICF-CY, can lead to better health and well-being for all.

  10. More concerns and stronger beliefs about the necessity of medication in patients with acromegaly are associated with negative illness perceptions and impairment in quality of life.

    Science.gov (United States)

    Andela, Cornelie D; Biermasz, Nienke R; Kaptein, Adrian A; Pereira, Alberto M; Tiemensma, Jitske

    2015-10-01

    Patients with acromegaly can be treated with surgery, radiotherapy and/or medical treatment. In general, patients' beliefs about medication are associated with illness perceptions, a contributory factor of Quality of Life (QoL). At present, there are no quantitative studies on medication beliefs in patients with acromegaly. Here, we aimed to examine possible associations between medication beliefs, illness perceptions, and QoL. Furthermore we aimed to explore whether illness perceptions of patients with remission of acromegaly receiving medical treatment differ from patients without medical treatment. Cross-sectional evaluation of 73 patients with remission of acromegaly (n = 28 patients with medication, n = 45 without medication). The Beliefs about Medicines Questionnaire (BMQ), Illness Perception Questionnaire-Revised (IPQ-R), EuroQoL-5D, and AcroQoL were used for the assessment. Stronger beliefs about the necessity of medical treatment and stronger concerns about the adverse effects were associated with attributing more symptoms to acromegaly, perceiving more negative consequences, and having a stronger belief in a cyclical timeline (BMQ, all P Negative medication beliefs were related to more negative illness perceptions and worse disease-specific QoL. Patients receiving medical treatment for acromegaly tend to perceive a more chronic timeline of their disease, compared to patients with remission without medical treatment. These psychological factors need to be taken into account when treating patients and developing a psychosocial education program aiming to improve QoL. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Contrast media. Safety issues and ESUR guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Thomsen, H.S. (ed.) [Copenhagen Univ. Hospital, Herlev (Denmark). Dept. of Diagnostic Radiology 54E2

    2006-07-01

    In 1994 the European Society of Urogenital Radiology (ESUR) set up a committee to consider the safety of the contrast media used in radiology departments. Since then, the committee has questioned members, reviewed the literature, proposed guidelines, and discussed these proposals with participants at the annual symposia on urogenital radiology. This book represents the end result of this hard work. It contains all of the agreed guidelines, updated when necessary, and thereby comprehensively covers the many different safety issues relating to the diverse contrast media: barium contrast media, iodinated contrast media, MR contrast media (both gadolinium-based extracellular and organ-specific) and ultrasound contrast media. The prevention and treatment of both acute and delayed non-renal adverse reactions as well as the renal adverse reactions are covered in detail. The inclusion of all the ESUR guidelines within one book will offer an invaluable, unique and unparalleled resource. (orig.)

  12. Contrast media. Safety issues and ESUR guidelines

    International Nuclear Information System (INIS)

    Thomsen, H.S.

    2006-01-01

    In 1994 the European Society of Urogenital Radiology (ESUR) set up a committee to consider the safety of the contrast media used in radiology departments. Since then, the committee has questioned members, reviewed the literature, proposed guidelines, and discussed these proposals with participants at the annual symposia on urogenital radiology. This book represents the end result of this hard work. It contains all of the agreed guidelines, updated when necessary, and thereby comprehensively covers the many different safety issues relating to the diverse contrast media: barium contrast media, iodinated contrast media, MR contrast media (both gadolinium-based extracellular and organ-specific) and ultrasound contrast media. The prevention and treatment of both acute and delayed non-renal adverse reactions as well as the renal adverse reactions are covered in detail. The inclusion of all the ESUR guidelines within one book will offer an invaluable, unique and unparalleled resource. (orig.)

  13. Contrast-enhanced harmonic endoscopic ultrasound

    DEFF Research Database (Denmark)

    Săftoiu, A; Dietrich, C F; Vilmann, P

    2012-01-01

    Second-generation intravenous blood-pool ultrasound contrast agents are increasingly used in endoscopic ultrasound (EUS) for characterization of microvascularization, differential diagnosis of benign and malignant focal lesions, and improving staging and guidance of therapeutic procedures. Although...... initially used as Doppler signal enhancers, second-generation microbubble contrast agents are now used with specific contrast harmonic imaging techniques, which benefit from the highly nonlinear behavior of the microbubbles. Contrast-specific modes based on multi-pulse technology are used to perform...... contrast-enhanced harmonic EUS based on a very low mechanical index (0.08 - 0.12). Quantification techniques based on dynamic contrast-enhanced ultrasound have been recommended for perfusion imaging and monitoring of anti-angiogenic treatment, mainly based on time-intensity curve analysis. Most...

  14. Multi-step contrast sensitivity gauge

    Science.gov (United States)

    Quintana, Enrico C; Thompson, Kyle R; Moore, David G; Heister, Jack D; Poland, Richard W; Ellegood, John P; Hodges, George K; Prindville, James E

    2014-10-14

    An X-ray contrast sensitivity gauge is described herein. The contrast sensitivity gauge comprises a plurality of steps of varying thicknesses. Each step in the gauge includes a plurality of recesses of differing depths, wherein the depths are a function of the thickness of their respective step. An X-ray image of the gauge is analyzed to determine a contrast-to-noise ratio of a detector employed to generate the image.

  15. Contrast settling in cerebral aneurysm angiography

    International Nuclear Information System (INIS)

    Wang Zhijie; Hoffmann, Kenneth R; Guterman, Lee R; Wang Zhou; Rudin, Stephen; Meng Hui

    2005-01-01

    During angiography, blood flow is visualized with a radiopaque contrast agent, which is denser than blood. In complex vasculature, such as cerebral saccular aneurysms, the density difference may produce an appreciable gravity effect, where the contrast material separates from blood and settles along the gravity direction. Although contrast settling has been occasionally reported before, the fluid mechanics behind it have not been explored. Furthermore, the severity of contrast settling in cerebral aneurysms varies significantly from case to case. Therefore, a better understanding of the physical principles behind this phenomenon is needed to evaluate contrast settling in clinical angiography. In this study, flow in two identical groups of sidewall aneurysm models with varying parent-vessel curvature was examined by angiography. Intravascular stents were deployed into one group of the models. To detect contrast settling, we used lateral view angiography. Time-intensity curves were analysed from the angiographic data, and a computational fluid dynamic analysis was conducted. Results showed that contrast settling was strongly related to the local flow dynamics. We used the Froude number, a ratio of flow inertia to gravity force, to characterize the significance of gravity force. An aneurysm with a larger vessel curvature experienced higher flow, which resulted in a larger Froude number and, thus, less gravitational settling. Addition of a stent reduced the aneurysmal flow, thereby increasing the contrast settling. We found that contrast settling resulted in an elevated washout tail in the time-intensity curve. However, this signature is not unique to contrast settling. To determine whether contrast settling is present, a lateral view should be obtained in addition to the anteroposterior (AP) view routinely used clinically so as to rule out contrast settling and hence to enable a valid time-intensity curve analysis of blood flow in the aneurysm

  16. Contrast media on abdominal computed tomography

    International Nuclear Information System (INIS)

    Skalpe, I.O.; Oestensen, H.M.

    1984-01-01

    Abdominal computed tomography was performed in 55 patients before and after intravenous injection of 60 ml of a non-ionic (iohexol) or an ionic (metrizoate) contrast medium. The adverse effects were recorded and a series of measurements of attenuation values before and after the contrast medium injection was performed in the aorta and in hepatic and renal parenchyma. Only minor adverse effects were seen with both contrast media, but iohexol was clearly better tolerated than metrizoate. No difference in the enhancement properties was found between the two contrast media. (orig.)

  17. An Improved Image Contrast Assessment Method

    Directory of Open Access Journals (Sweden)

    Yuanyuan Fan

    2013-07-01

    Full Text Available Contrast is an important factor affecting the image quality. In order to overcome the problems of local band-limited contrast, a novel image contrast assessment method based on the property of HVS is proposed. Firstly, the image by low-pass filter is performed fast wavelet decomposition. Secondly, all levels of band-pass filtered image and its corresponding low-pass filtered image are obtained by processing wavelet coefficients. Thirdly, local band-limited contrast is calculated, and the local band-limited contrast entropy is calculated according to the definition of entropy, Finally, the contrast entropy of image is obtained by averaging the local band-limited contrast entropy weighed using CSF coefficient. The experiment results show that the best contrast image can be accurately identified in the sequence images obtained by adjusting the exposure time and stretching gray respectively, the assessment results accord with human visual characteristics and make up the lack of local band-limited contrast.

  18. Contrast enhanced ultrasound in liver imaging

    International Nuclear Information System (INIS)

    Nielsen, Michael Bachmann; Bang, Nanna

    2004-01-01

    Ultrasound contrast agents were originally introduced to enhance the Doppler signals when detecting vessels with low velocity flow or when imaging conditions were sub-optimal. Contrast agents showed additional properties, it was discovered that a parenchymal enhancement phase in the liver followed the enhancement of the blood pool. Contrast agents have made ultrasound scanning more accurate in detection and characterization of focal hepatic lesions and the sensitivity is now comparable with CT and MRI scanning. Further, analysis of the transit time of contrast agent through the liver seems to give information on possible hepatic involvement, not only from focal lesions but also from diffuse benign parenchymal disease. The first ultrasound contrast agents were easily destroyed by the energy from the sound waves but newer agents have proved to last for longer time and hereby enable real-time scanning and make contrast enhancement suitable for interventional procedures such as biopsies and tissue ablation. Also, in monitoring the effect of tumour treatment contrast agents have been useful. A brief overview is given on some possible applications and on different techniques using ultrasound contrast agents in liver imaging. At present, the use of an ultrasound contrast agent that allows real-time scanning with low mechanical index is to be preferred

  19. Polymeric nanoparticles as OCT contrast agents

    Energy Technology Data Exchange (ETDEWEB)

    Al Rawashdeh, Wa' el [RWTH Aachen University, Experimental Molecular Imaging (Germany); Kray, Stefan [RWTH Aachen University, Institute for Semiconductor Electronics (Germany); Pich, Andrij; Pargen, Sascha; Balaceanu, Andreea [RWTH Aachen University, Interactive Material Research (DWI) (Germany); Lenz, Markus; Spoeler, Felix [RWTH Aachen University, Institute for Semiconductor Electronics (Germany); Kiessling, Fabian, E-mail: fkiessling@ukaachen.de; Lederle, Wiltrud [RWTH Aachen University, Experimental Molecular Imaging (Germany)

    2012-12-15

    In this study, the optical properties of two nano-sized polymer colloids in optical coherence tomography (OCT) were compared in vitro with respect to their potential use as contrast agents. We used two types of particles: compact hydrophobic spherical polystyrene (PS) particles and soft water-swollen nanogel (NG) particles both with grafted hydrophilic shell, both prepared at two different sizes (PS at 300 and 150 nm, NG at 300 and 200 nm). The OCT backscattering signals of the particles in a vessel-mimicking highly scattering agar/TiO{sub 2} phantom were compared on either number of particles or weight percent. Larger particles and higher concentrations produced higher OCT contrast. At each concentration tested, a markedly higher contrast was achieved by PS particles than NG particles. PS particles generated a markedly higher OCT contrast than the phantom at concentrations of at least 1 Multiplication-Sign 10{sup 10} or 0.1 % for PS 300 nm and at least 3 Multiplication-Sign 10{sup 11} particles/mL or 0.4 % for PS 150 nm. The contrast generated by NG 300 nm was above the phantom contrast at concentrations of at least 3 Multiplication-Sign 10{sup 11} particles/mL or 1 %, whereas NG 200 nm only at 4 %. At any given weight percent, the differences in OCT contrast between differently sized particles were much less evident than in the comparison based on particle number. PS 300 nm generated also a good contrast ex vivo on chicken muscle tissue. These results strongly suggest that PS spheres have strong potential as intravascular OCT contrast agent, while NG particles need further contrast enhancer for being used as OCT contrast agent.

  20. Motion contrast using optical coherence tomography

    Science.gov (United States)

    Fingler, Jeffrey Paul

    Diagnosis of ophthalmic diseases like age-related macular degeneration is very important for treatment of the disease as well as the development of future treatments. Optical coherence tomography (OCT) is an optical interference technique which can measure the three-dimensional structural information of the reflecting layers within a sample. In retinal imaging, OCT is used as the primary diagnostic tool for structural abnormalities such as retinal holes and detachments. The contrast within the images of this technique is based upon reflectivity changes from different regions of the retina. This thesis demonstrates the developments of methods used to produce additional contrast to the structural OCT images based on the tiny fluctuations of motion experienced by the mobile scatterers within a sample. Motion contrast was observed for motions smaller than 50 nm in images of a variety of samples. Initial contrast method demonstrations used Brownian motion differences to separate regions of a mobile Intralipid solution from a static agarose gel, chosen in concentration to minimize reflectivity contrast. Zebrafish embryos in the range of 3-4 days post fertilization were imaged using several motion contrast methods to determine the capabilities of identifying regions of vascular flow. Vasculature identification was demonstrated in zebrafish for blood vessels of all orientations as small as 10 microns in diameter. Mouse retinal imaging utilized the same motion contrast methods to determine the contrast capabilities for motions associated with vasculature within the retina. Improved contrast imaging techniques demonstrated comparable images to fluorescein angiography, the gold standard of retinal vascular imaging. Future studies can improve the demonstrated contrast analysis techniques and apply them towards human retinal motion contrast imaging for ophthalmic diagnostic purposes.

  1. CHANGE DETECTION VIA SELECTIVE GUIDED CONTRASTING FILTERS

    Directory of Open Access Journals (Sweden)

    Y. V. Vizilter

    2017-05-01

    Full Text Available Change detection scheme based on guided contrasting was previously proposed. Guided contrasting filter takes two images (test and sample as input and forms the output as filtered version of test image. Such filter preserves the similar details and smooths the non-similar details of test image with respect to sample image. Due to this the difference between test image and its filtered version (difference map could be a basis for robust change detection. Guided contrasting is performed in two steps: at the first step some smoothing operator (SO is applied for elimination of test image details; at the second step all matched details are restored with local contrast proportional to the value of some local similarity coefficient (LSC. The guided contrasting filter was proposed based on local average smoothing as SO and local linear correlation as LSC. In this paper we propose and implement new set of selective guided contrasting filters based on different combinations of various SO and thresholded LSC. Linear average and Gaussian smoothing, nonlinear median filtering, morphological opening and closing are considered as SO. Local linear correlation coefficient, morphological correlation coefficient (MCC, mutual information, mean square MCC and geometrical correlation coefficients are applied as LSC. Thresholding of LSC allows operating with non-normalized LSC and enhancing the selective properties of guided contrasting filters: details are either totally recovered or not recovered at all after the smoothing. These different guided contrasting filters are tested as a part of previously proposed change detection pipeline, which contains following stages: guided contrasting filtering on image pyramid, calculation of difference map, binarization, extraction of change proposals and testing change proposals using local MCC. Experiments on real and simulated image bases demonstrate the applicability of all proposed selective guided contrasting filters. All

  2. Comparative evaluation of positive contrast and double contrast gastrography in dogs

    International Nuclear Information System (INIS)

    Dileepkumar, K.M.; Rajankutty, K.; Sarada, Amma T.; Devanand, C.B.; Vijayan, N.

    2012-01-01

    A contrast radiography of stomach with oral barium sulphate suspension 25% (5 mL/kg b.wt positive contrast) and double contrast with oral barium sulphate 25% (3 mL/kg b.wt) followed by air (2 to 10 mL/kg b.wt, negative contrast) was done on six dogs to study the affections of stomach. Contrast radiography using barium sulphate alone was found satisfactory to identify most of the lesions of the stomach. Double contrast radiography using barium sulphate and air, required sedation to control the animals for proper administration. For the diagnosis of mucosal lesions, double contrast radiography was better than barium sulphate alone. Key words: Barium, Contrast radiography, Dog, Double contrast, Stomach

  3. Contrasts agents in magnetic resonance imaging

    International Nuclear Information System (INIS)

    Bonnet, P.A.; Fernandez, J.P.; Milhavet, J.C.; Chapat, J.P.; Almes, C.; Bruel, J.M.; Rouanet, J.P.; Lamarque, J.L.

    1984-01-01

    Changing different parameters involved in imaging procedures, paramagnetic substances provide contrast enhancement in MRI. Contrast agents presently studied in animals and clinical trials, are either salts or complexes of mineral ions either nitroxide stable free radicals. Their development should extend the possibilities of tissular characterization and fonctional or metabolic evaluation of the MRI [fr

  4. Parametric based morphological transformation for contrast ...

    Indian Academy of Sciences (India)

    for contrast enhancement of color images in poor-lighting ... high and low mean brightness value, there is a significant change in the view of the enhanced ... The two most fundamental morphological operations dilation and erosion are defined by ..... Menotti David 2007 Multi-histogram equalization methods for contrast ...

  5. Discrimination of Arabic Contrasts by American Learners

    Science.gov (United States)

    Al Mahmoud, Mahmoud S.

    2013-01-01

    This article reports on second language perception of non-native contrasts. The study specifically tests the perceptual assimilation model (PAM) by examining American learners' ability to discriminate Arabic contrasts. Twenty two native American speakers enrolled in a university level Arabic language program took part in a forced choice AXB…

  6. Comparison and Contrast in Perceptual Categorization

    Science.gov (United States)

    Hampton, James A.; Estes, Zachary; Simmons, Claire L.

    2005-01-01

    People categorized pairs of perceptual stimuli that varied in both category membership and pairwise similarity. Experiments 1 and 2 showed categorization of 1 color of a pair to be reliably contrasted from that of the other. This similarity-based contrast effect occurred only when the context stimulus was relevant for the categorization of the…

  7. Contrast sensitivity abnormalities in deaf individuals

    Directory of Open Access Journals (Sweden)

    Masoud Khorrami-Nejad

    2018-01-01

    Conclusion: Hearing impaired boys are at a greater risk for contrast sensitivity abnormalities than boys with normal hearing. The larger frequency of contrast sensitivity abnormalities in high spatial frequencies than in other frequencies may demonstrate greater defects in the central visual system compared with the periphery in individuals with hearing loss.

  8. Influence of radiographic contrast media on phagocytosis

    International Nuclear Information System (INIS)

    Rasmussen, F.; Georgsen, J.; Grunnet, N.; Aalborg Sygehus

    1988-01-01

    To evaluate the influence of radiographic contrast media (CM) on human polymorphonuclear leucocytes (PML), the ability of these cells to ingest latex particles after in vitro exposure to five different radiographic contrast media was investigated. All CM inhibited the phagocytic properties of PML. The inhibition was dose dependent. The inhibitory effect was partly due to hyperosmolality but CM specific inhibition was also evident. (orig.)

  9. Modeling of ultrasound propagation through contrast agents

    NARCIS (Netherlands)

    Grootens, J.J.F.A.H.; Mischi, M.; Böhmer, M.; Korsten, H.; Aarts, R.M.; Vander Sloten, Jos; Verdonck, Pascal; Nyssen, Marc

    2008-01-01

    In the past years many advances have been made in the detection of ultrasound contrast agents (UCA) by exploiting their nonlinear behavior. However, little attention has been paid to the nonlinear distortion of ultrasound (US) waves propagating through contrast media. The aim of this study is to

  10. Adverse reactions to intravascularly administered contrast media

    International Nuclear Information System (INIS)

    Olin, T.

    1986-01-01

    A hypothesis is formulated about the mechanisms causing adverse reactions to contrast media. Contrast media act in two ways. They stimulate the mast cells to release histamine and leukotrienes, and they inhibit the enzymes which otherwise degrade leukotrienes. Thus individuals, especially those with a history of allergy, are easily exposed to undue amounts of leukotrienes and these are responsible for the adverse reactions. (orig.)

  11. Lesion Contrast Enhancement in Medical Ultrasound Imaging

    DEFF Research Database (Denmark)

    Stetson, Paul F.; Sommer, F.G.; Macovski, A.

    1997-01-01

    Methods for improving the contrast-to-noise ratio (CNR) of low-contrast lesions in medical ultrasound imaging are described. Differences in the frequency spectra and amplitude distributions of the lesion and its surroundings can be used to increase the CNR of the lesion relative to the background...

  12. Conjunctions of colour, luminance and orientation: the role of colour and luminance contrast on saliency and proximity grouping in texture segregation.

    Science.gov (United States)

    Leonards, U; Singer, W

    2000-01-01

    To examine whether perceptual grouping on the basis of orientation can be performed simultaneously with or only subsequently to grouping according to colour or luminance, we tested whether subjects are able to segregate arrays of texture elements that differ from surrounding elements by conjunctions of either (i) colour and orientation, or (ii) luminance contrast and orientation, or (iii) luminance contrast polarity and orientation. Subjects were able to use conjunctions between luminance and orientation for segregation but not conjunctions between colour or contrast polarity and orientation. Our results suggest that (i) in agreement with earlier findings, there seem to exist no specific conjunction detectors for colour and orientation or contrast polarity and orientation, and (ii) when orientation defined textures are to be distinguished by virtue of differences in luminance, colour, or contrast polarity, luminance provides a much stronger cue than colour or contrast polarity for saliency-based orientation grouping.

  13. Contrast configuration influences grouping in apparent motion.

    Science.gov (United States)

    Ma-Wyatt, Anna; Clifford, Colin W G; Wenderoth, Peter

    2005-01-01

    We investigated whether the same principles that influence grouping in static displays also influence grouping in apparent motion. Using the Ternus display, we found that the proportion of group motion reports was influenced by changes in contrast configuration. Subjects made judgments of completion of these same configurations in a static display. Generally, contrast configurations that induced a high proportion of group motion responses were judged as more 'complete' in static displays. Using a stereo display, we then tested whether stereo information and T-junction information were critical for this increase in group motion. Perceived grouping was consistently higher for same contrast polarity configurations than for opposite contrast polarity configurations, regardless of the presence of stereo information or explicit T-junctions. Thus, while grouping in static and moving displays showed a similar dependence on contrast configuration, motion grouping showed little dependence on stereo or T-junction information.

  14. Contrast Agent in Magnetic Resonance Imaging

    DEFF Research Database (Denmark)

    Vu-Quang, Hieu

    2015-01-01

    Nanoparticles have been employed as contrast agent in magnetic resonance imaging (MRI) in order to improve sensitivity and accuracy in diagnosis. In addition, these contrast agents are potentially combined with other therapeutic compounds or near infrared bio-imaging (NIR) fluorophores to obtain...... theranostic or dual imaging purposes, respectively. There were two main types of MRI contrast agent that were synthesized during this PhD project including fluorine containing nanoparticles and magnetic nanoparticles. In regard of fluorine containing nanoparticles, there were two types contrast agent...... cancer cells for cancer diagnosis in MRI. F127-Folate coated SPION were stable in various types of suspension medium for over six months. They could specifically target folate receptor of cancer cells in vitro and in vivo thus enhancing the contrast in MRI T2/T2* weighted images. These are preliminary...

  15. Application of phase contrast imaging to mammography

    International Nuclear Information System (INIS)

    Tohyama, Keiko; Yamada, Katsuhiko; Katafuchi, Tetsuro; Matsuo, Satoru; Morishita, Junji

    2005-01-01

    Phase contrast images were obtained experimentally by using a customized mammography unit with a nominal focal spot size of 100 μm and variable source-to-image distances of up to 1.5 m. The purpose of this study was to examine the applicability and potential usefulness of phase contrast imaging for mammography. A mammography phantom (ACR156 RMI phantom) was imaged, and its visibility was examined. The optical density of the phantom images was adjusted to approximately 1.3 for both the contact and phase contrast images. Forty-one observers (18 medical doctors and 23 radiological technologists) participated in visual evaluation of the images. Results showed that, in comparison with the images of contact mammography, the phantom images of phase contrast imaging demonstrated statistically significantly superior visibility for fibers, clustered micro-calcifications, and masses. Therefore, phase contrast imaging obtained by using the customized mammography unit would be useful for improving diagnostic accuracy in mammography. (author)

  16. Quantitative analysis of enhanced malignant and benign lesions on contrast-enhanced spectral mammography.

    Science.gov (United States)

    Deng, Chih-Ying; Juan, Yu-Hsiang; Cheung, Yun-Chung; Lin, Yu-Ching; Lo, Yung-Feng; Lin, GiGin; Chen, Shin-Cheh; Ng, Shu-Hang

    2018-02-27

    To retrospectively analyze the quantitative measurement and kinetic enhancement among pathologically proven benign and malignant lesions using contrast-enhanced spectral mammography (CESM). We investigated the differences in enhancement between 44 benign and 108 malignant breast lesions in CESM, quantifying the extent of enhancements and the relative enhancements between early (between 2-3 min after contrast medium injection) and late (3-6 min) phases. The enhancement was statistically stronger in malignancies compared to benign lesions, with good performance by the receiver operating characteristic curve [0.877, 95% confidence interval (0.813-0.941)]. Using optimal cut-off value at 220.94 according to Youden index, the sensitivity was 75.9%, specificity 88.6%, positive likelihood ratio 6.681, negative likelihood ratio 0.272 and accuracy 82.3%. The relative enhancement patterns of benign and malignant lesions, showing 29.92 vs 73.08% in the elevated pattern, 7.14 vs 92.86% in the steady pattern, 5.71 vs 94.29% in the depressed pattern, and 80.00 vs 20.00% in non-enhanced lesions (p < 0.0001), respectively. Despite variations in the degree of tumour angiogenesis, quantitative analysis of the breast lesions on CESM documented the malignancies had distinctive stronger enhancement and depressed relative enhancement patterns than benign lesions. Advances in knowledge: To our knowledge, this is the first study evaluating the feasibility of quantifying lesion enhancement on CESM. The quantities of enhancement were informative for assessing breast lesions in which the malignancies had stronger enhancement and more relative depressed enhancement than the benign lesions.

  17. Choice of intravenous contrast material for CT

    International Nuclear Information System (INIS)

    Cohen, M.D.; Herman, E.; Herron, D.; White, S.T.; Smith, J.A.; Cory, D.A.

    1989-01-01

    For CT, minor side effects (e.g., nausea, vomiting, pain) following intravenous administration of contrast medium may degrade image quality by causing patient motion or by delaying scanning. The objective of this study was to see if nonionic contrast agents offer advantages in reducing the incidence of such side effects. One hundred five pediatric patients randomly received iohexol (Omnipaque), Iopamidol (Isovue), or diatrizoate sodium (Hypaque). Contrast medium was given in doses of 2 mL/kg body weight (300 mg of iodine per milliliter). The results are presented in the paper

  18. Anaphylactoid reactions after iodinated contrast media

    International Nuclear Information System (INIS)

    Strejcek, J.; Sehr, A.

    1987-01-01

    A survey is presented of data published in the literature on the incidence of undesirable and especially anaphylactoid reactions to intravenously administered iodinated contrast media used in radiodiagnosis, this with regard to age, sex, allergy in the patient's history, previously administered contrast media, possible previous reaction. A detailed description is presented of the assumed mechanisms of these reactions. There does not exist any reliable premedication. It is always indispensable to consider the indications of the examination using iodinated contrast agents and the possibilities of immediate and qualified resuscitation. (author). 2 tabs., 36 refs

  19. Contrast data mining concepts, algorithms, and applications

    CERN Document Server

    Dong, Guozhu

    2012-01-01

    A Fruitful Field for Researching Data Mining Methodology and for Solving Real-Life Problems Contrast Data Mining: Concepts, Algorithms, and Applications collects recent results from this specialized area of data mining that have previously been scattered in the literature, making them more accessible to researchers and developers in data mining and other fields. The book not only presents concepts and techniques for contrast data mining, but also explores the use of contrast mining to solve challenging problems in various scientific, medical, and business domains. Learn from Real Case Studies

  20. Faster-higher-stronger -- greener

    International Nuclear Information System (INIS)

    Burgess, A.

    2000-01-01

    The Toronto Olympic Bid Committee is reported to have adopted a strong environmental orientation in its bid to bring the 2008 Olympic Games to Toronto. In a recent address, the President of the Committee outlined details of the bid's environmental component which emphasizes the role of sustainable development within the Olympics and the consequences of this orientation on the design, construction and operation of facilities. The Toronto Bid Committee has gained inspiration and momentum for its 'green bid' from the host city of the 2000 Olympic Games, Sidney, Australia, which has won widespread praise for its efforts to clean up Homebush Bay, a brownfield site long seen as a liability for the city. The Toronto Bid Committee is making itself accountable for: creating the healthiest possible conditions for the athletes, visitors and residents; designing for sustainability; protecting, restoring and enhancing human and natural habitats; conserving resources and minimizing the ecological impact of the Games; promoting innovative, technically proven Canadian environmental technology; and fostering environmental awareness and education. The Committee intends to make the environment a priority and not just an afterthought in the bidding process. It hopes to develop specific goals and where possible, quantifiable targets in non-polluting designs for all Olympic housing and sports facilities. Wherever possible renewable power such as wind, solar and fuel cells will be used, and cleaner fuels such as natural gas where green power is not a viable option

  1. Are melanized feather barbs stronger?

    Science.gov (United States)

    Butler, Michael; Johnson, Amy S

    2004-01-01

    Melanin has been associated with increased resistance to abrasion, decreased wear and lowered barb breakage in feathers. But, this association was inferred without considering barb position along the rachis as a potentially confounding variable. We examined the cross-sectional area, breaking force, breaking stress, breaking strain and toughness of melanized and unmelanized barbs along the entire rachis of a primary feather from an osprey (Pandion haliaetus). Although breaking force was higher for melanized barbs, breaking stress (force divided by cross-sectional area) was greater for unmelanized barbs. But when position was considered, all mechanical differences between melanized and unmelanized barbs disappeared. Barb breaking stress, breaking strain and toughness decreased, and breaking stiffness increased, distally along the rachis. These proximal-distal material property changes are small and seem unlikely to affect flight performance of barbs. Our observations of barb bending, breaking and morphology, however, lead us to propose a design principle for barbs. We propose that, by being thicker-walled dorso-ventrally, the barb's flexural stiffness is increased during flight; but, by allowing for twisting when loaded with dangerously high forces, barbs firstly avoid failure by bending and secondly avoid complete failure by buckling rather than rupturing.

  2. A stronger perfume for LPG

    Energy Technology Data Exchange (ETDEWEB)

    Willcox, C.K.

    1996-11-01

    The odorisation of Liquefied Petroleum Gas (LPG) is undertaken to improve the safe use and transport of this popular fuel. Effective LPG odorisation should enable leaks to be detected by any person with a normal sense of smell before gas concentrations reach a hazardous level. The objective is identical to that for odorising natural gas. However, the physical characteristics of propane and butane present particular difficulties. These do not occur with natural gas, which has a dynamic, flowing, simple-phase system. (author)

  3. A stronger perfume for LPG

    International Nuclear Information System (INIS)

    Willcox, C.K.

    1996-01-01

    The odorisation of Liquefied Petroleum Gas (LPG) is undertaken to improve the safe use and transport of this popular fuel. Effective LPG odorisation should enable leaks to be detected by any person with a normal sense of smell before gas concentrations reach a hazardous level. The objective is identical to that for odorising natural gas. However, the physical characteristics of propane and butane present particular difficulties. These do not occur with natural gas, which has a dynamic, flowing, simple-phase system. (author)

  4. Bad is stronger than good

    NARCIS (Netherlands)

    Baumeister, R.F.; Bratslavsky, E.; Finkenauer, C.; Vohs, K.D.

    2001-01-01

    The greater power of bad events over good ones is found in everyday events, major life events (e.g., trauma), close relationship outcomes, social network patterns, interpersonal interactions, and learning processes. Bad emotions, bad parents, and bad feedback have more impact than good ones, and bad

  5. Working Longer Makes Students Stronger?

    DEFF Research Database (Denmark)

    Jensen, Vibeke Myrup

    Abstract: Despite much discussion on the role of education policy on school and student performance, we know little about the effects of school spending at the margin on student cognitive achievement beyond the effects of class size. Thus this paper examines the effects of annual ninth grade...... classroom hours in literacy and maths on ninth grade (aged 16) student performance in writing and maths, respectively. Using population data for Denmark in 2003-2006, I exploit unique policy-induced variation in classroom hours.On average, the reform changed classroom hours by 2.2-3.3% in literacy and maths...

  6. The polar 2e/12c bond in phenalenyl-azaphenalenyl hetero-dimers: Stronger stacking interaction and fascinating interlayer charge transfer

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Rong-Lin; Li, Zhi-Ru, E-mail: hlxu@nenu.edu.cn, E-mail: lzr@jlu.edu.cn [Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China); Xu, Hong-Liang, E-mail: hlxu@nenu.edu.cn, E-mail: lzr@jlu.edu.cn [Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)

    2016-08-07

    An increasing number of chemists have focused on the two-electron/multicenter bond (2e/mc) that was first introduced to interpret the bonding mechanism of radical dimers. Herein, we report the polar two-electron/twelve center (2e/12c) bonding character in a series of phenalenyl-azaphenalenyl radical hetero-dimers. Interestingly, the bonding energy of weaker polar hetero-dimer (P-TAP) is dominated by the overlap of the two different singly occupied molecular orbital of radicals, while that of stronger polar hetero-dimer (P-HAP) is dominated by the electrostatic attraction. Results show that the difference between the electronegativity of the monomers plays a prominent role in the essential attribution of the polar 2e/12c bond. Correspondingly, a stronger stacking interaction in the hetero-dimer could be effectively achieved by increasing the difference of nitrogen atoms number between the monomers. It is worthy of note that an interesting interlayer charge transfer character is induced in the polar hetero-dimers, which is dependent on the difference between the electronegativity of the monomers. It is our expectation that the new knowledge about the bonding nature of radical hetero-dimers might provide important information for designing radical based functional materials with various applications.

  7. The 'humble' bubble: Contrast-enhanced ultrasound

    International Nuclear Information System (INIS)

    Marshall, Gill; Sykes, Anne; Berry, Jonathan; Jonker, Leon

    2011-01-01

    The use of contrast-enhanced ultrasound (CEUS) is increasing within the field of medical imaging. Ultrasonic contrast agent (UCA) contain gas microbubbles similar in size to red corpuscles which provide highly reflective interfaces, enabling dynamic demonstration of echogenic streams of the contrast within the anatomical area of interest on real-time grey scale ultrasound. Longevity of the microbubbles has been improved by changing their composition. The application of CEUS in the UK continues to grow, bringing it into territories historically occupied by computerised tomography (CT) scanning and magnetic resonance imaging (MRI). Hence, the role of CEUS may be of interest to all diagnostic imaging practitioners. Here we summarise the mode of action and use of CEUS, and its role within a range of applications. The potential risks of CEUS are compared to other contrast-enhanced imaging techniques. The benefits of CEUS and its implications for diagnostic imaging practice are also covered.

  8. Contrast effects of a gadolinium filter

    International Nuclear Information System (INIS)

    Burgess, A.E.

    1981-01-01

    Several authors have suggested using heavy metal filters with K edges in the diagnostic energy range to reduce the width of the x-ray spectrum and hence reduce patient radiation exposure. This spectral narrowing also increases subject contrast and permits an increase in tube potential. Results of contrast measurements are presented for a 250 mu gadolinium filter. It was found that aluminum filter contrast could be matched by using 8 to 10 kVp higher potential with the gadolinium filter. Similar results were found for calcium tungstate and rare-earth screens. Measurements were also done to determine skin exposure and mAs ratios for both constant contrast and constant kVp technique conversion methods. A simple theory with one adjustable parameter gives a reasonable fit to the experimental results

  9. Incompatibility of Contrast Medium and Trisodium Citrate

    International Nuclear Information System (INIS)

    Delcour, Christian; Bruninx, Guy

    2013-01-01

    To test the compatibility of trisodium citrate, a catheter lock solution, with iodinated contrast medium. Iohexol, iobitridol, iodixanol, ioxaglate, ioxithalamate, iomeprol, and iopromide were tested. In all tests, 2 ml of contrast medium were mixed with 2 ml of trisodium citrate solution. Iodixanol and ioxaglate provoked a highly viscous gluelike precipitation when mixed with trisodium citrate. A brief transient precipitate was observed with iohexol, iomeprol, and ioxithalamate. Permanent precipitation occurred with iobitridol and iopromide. One must be aware of the potential for precipitation when contrast medium is mixed with trisodium citrate solution. Before trisodium citrate solution is injected, the catheter should be thoroughly flushed with saline if a contrast medium has previously been injected through it.

  10. Manganese(II) chelate contrast media

    International Nuclear Information System (INIS)

    Rocklage, S.M.; Quay, S.C.

    1994-01-01

    New chelate forming compounds for use as contrast media in NMR imaging are described. Especially mentioned are manganese(II) ion chelates of N,N' dipyridoxaldiamine, N,N' diacetic acid, and salts and esters thereof. 1 fig

  11. Application of Contrast Echocardiography in Invasive Cardiology

    Directory of Open Access Journals (Sweden)

    Mustafa Bulut

    2010-12-01

    Full Text Available Contrast echocardiography by rendering better imaging of the borders of cardiac chambers is a useful tool for evaluating cardiac function, mass, myocardial vascularization, microvascular structure (small vessel vasculature and viability. Contrast was first started to be used for patients with suboptimal image quality. It can be used in detecting defects in myocardial blood supply in patients with chest pain and determining the success of interventionalprocedures. It can also be of help in demonstrating myocardial viability after reperfusion treatment in patients who had myocardial infarction. It is expected to be used more widely in invasive cardiology for decision making, guiding and determining the success of the procedures. Advances in imaging techniques , development of contrast materials for evaluation of left system, contrast echocardiography may become a routine clinical practice.

  12. Safety of MR liver specific contrast media

    Energy Technology Data Exchange (ETDEWEB)

    Bellin, Marie-France [Hopital Paul Brousse, Universite Paris 11, Villejuif Cedex (France); Webb, Judith A.W. [St. Bartholomew' s Hospital, Department of Diagnostic Imaging, London (United Kingdom); Molen, Aart J. van der [Leiden University Medical Centre, Department of Radiology, Leiden (Netherlands); Thomsen, Henrik S. [Copenhagen University Hospital at Herlev, Department of Diagnostic Radiology 54E2, Herlev (Denmark); Morcos, Sameh K. [Northern General Hospital, Sheffield Teaching Hospitals NHS Trust, Department of Diagnostic Imaging, Sheffield (United Kingdom)

    2005-08-01

    Over the past few years a number of magnetic resonance (MR) liver specific contrast agents have been introduced. In this report the safety issues of these agents are addressed. A literature search was carried out. Based on the available information, simple guidelines on the safety issue of liver specific contrast agents have been produced by the Contrast Media Safety Committee of the European Society of Urogenital Radiology. The report and guidelines were discussed at the 11th European Symposium on Urogenital Radiology in Santiago de Compostela. Liver specific contrast agents appear in general to be safe and well tolerated. However, the incidence of adverse reactions with iron oxides and the intravenous manganese based agent seems to be slightly higher than with gadolinium based agents. However, no safety information from comparative clinical trials has been published. Guidelines on the safety aspects are presented. (orig.)

  13. Safety of MR liver specific contrast media

    International Nuclear Information System (INIS)

    Bellin, Marie-France; Webb, Judith A.W.; Molen, Aart J. van der; Thomsen, Henrik S.; Morcos, Sameh K.

    2005-01-01

    Over the past few years a number of magnetic resonance (MR) liver specific contrast agents have been introduced. In this report the safety issues of these agents are addressed. A literature search was carried out. Based on the available information, simple guidelines on the safety issue of liver specific contrast agents have been produced by the Contrast Media Safety Committee of the European Society of Urogenital Radiology. The report and guidelines were discussed at the 11th European Symposium on Urogenital Radiology in Santiago de Compostela. Liver specific contrast agents appear in general to be safe and well tolerated. However, the incidence of adverse reactions with iron oxides and the intravenous manganese based agent seems to be slightly higher than with gadolinium based agents. However, no safety information from comparative clinical trials has been published. Guidelines on the safety aspects are presented. (orig.)

  14. Contrast medium-induced nephropathy: the pathophysiology

    DEFF Research Database (Denmark)

    Persson, P B; Tepel, Martin

    2006-01-01

    A widespread, rather general, definition of contrast-induced nephropathy (CIN) is an impairment in renal function occurring within 3 days following the intravascular administration of contrast media (CM) and the absence of an alternative aetiology. In spite of the vast clinical importance of CIN...... haemodynamics, regional hypoxia, auto-, and paracrine factors (adenosine, endothelin, reactive oxygen species) to direct cytotoxic effects. Although these potential mediators of CIN will be discussed separately, several factors may act in concert to perturb kidney function after exposure to contrast media. From...... the current knowledge of the mechanisms causing CIN, it is not possible to recommend a certain class of contrast media, except to avoid large doses of CM of the first generation. From a pathophysiological perspective, volume expansion is effective in avoiding CIN, since water permeability of the collecting...

  15. Basic characteristics of simultaneous color contrast revisited.

    Science.gov (United States)

    Ekroll, Vebjørn; Faul, Franz

    2012-10-01

    In this article, we present evidence supporting the hypothesis that the local mechanism of simultaneous color contrast is the same as the mechanism responsible for the crispening effect and the gamut expansion effect. A theoretically important corollary of this hypothesis is that the basic characteristics of simultaneous contrast are at odds with traditional laws. First, this hypothesis implies that the direction of the simultaneous contrast effect in color space is given by the vector from surround to target and not--as traditionally assumed--by the hue complementary to that of the surround. Second, it implies that the size of the simultaneous contrast effect depends on the difference between the target and surround colors in a way that challenges Kirschmann's fourth law. The widespread belief in the traditional laws, we argue, is due to the confounding influence of temporal adaptation.

  16. Are the nonionic contrast media really safe

    International Nuclear Information System (INIS)

    Seyferth, W.; Zeitler, E.

    1987-01-01

    The authors used a wide variety of ionic and nonionic contrast media in 11,203 patient examinations (angiography, phlebography, CT). Data have been collected in prospective studies since 1982. The rate of mild side effects was reduced by a factor of 2 to 3 for all examinations when nonionic contrast media were used. Angiography may not be suitable for evaluating the safety of contrast media. Because of statistical requirements, the influence of nonionic media on the rate of severe side effects will not be known for some time. The side effects of nonionic contrast media were somewhat delayed, and differed from times reported in the literature: 29% of wide effects were noticed within 15 minutes and 71% between 25 minutes to 72 hours after the study. The final results of the study will have numerous consequences for patient treatment protocols

  17. Death following intravascular administration of contrast media

    International Nuclear Information System (INIS)

    Shehadi, W.H.

    1985-01-01

    Adverse reactions to intravascularly administered contrast media preceding death and the autopsy findings in 44 patients are presented. There is a wide scatter of the age distribution of fatal reactions. The highest incidence is in the 50-70 year age group. Similar observations were obtained from the 405 deaths due to contrast media reported to the Food and Drug Administration of the United States. In the same age group the number of reactions is highest, likewise the autopsy findings. The predominant autopsy findings are pulmonary edema, congestion and hemorrhage; arteriosclerosis, both general and coronary. In the younger age group the autopsy findings are limited mostly to the respiratory tract. Fatal reactions to contrast media occur often without warning and most deaths occur within 15 min to 6 hours. Reactions to contrast media occur without relation to sex or age. (orig.)

  18. Contrast data mining: concepts, algorithms, and applications

    National Research Council Canada - National Science Library

    Dong, Guozhu; Bailey, James

    2013-01-01

    .... Contrasting involves the comparison of one dataset against another. The datasets may represent data of different time periods, spatial locations, or classes, or they may represent data satisfying different conditions...

  19. Instrumentation for contrast echocardiography: technology and techniques.

    Science.gov (United States)

    Kaul, Sanjiv

    2002-11-18

    Contrast echocardiography is the only clinical imaging technique in which the imaging modality (ultrasound) can cause a change in the contrast agent (microbubbles). The change in the contrast agent can range from small oscillations of the microbubbles at a low mechanical index to their disruption at a high mechanical index. The specific mechanical index required to produce these various effects may be different for each contrast agent, depending on the bubble dimension as well as shell and gas characteristics. These alterations in bubbles result in changes in ultrasound backscatter that are specific for the bubbles themselves, rather than for tissue, and are therefore exploited for imaging their presence in tissue. These signal-processing techniques have resulted in an increased signal-to-noise ratio from bubbles vis-à-vis the tissue and have made online assessment of myocardial perfusion possible.

  20. Parametric based morphological transformation for contrast ...

    Indian Academy of Sciences (India)

    rithm is illustrated through the processing of gray scale images and color images with different backgrounds. Keywords. Histogram equalization; image background; mathematical morphology; Weber's ratio. 1. Introduction. Contrast enhancement has a crucial role in image processing applications, such as digital.

  1. Contrast-induced nephropathy after computed tomography

    Directory of Open Access Journals (Sweden)

    Luciano da Silva Selistre

    2015-03-01

    Full Text Available Introduction: Contrast induced nephropathy is the third most prevalent preventable cause of acute kidney injury in hospitalized patients. It defined as an absolute increase in serum creatinine ≥ 0.5 mg/dL and relative ≥ 25% increase. Objective: We studied the risk factors to intravenous injection contrast nephropathy after computed tomography. Methods: We studied 400 patients prospectively. Results: The incidence of contrast induced nephropathy, with an absolute or a relative increase were 4.0% and 13.9%, respectively. Diabetes and cardiac failure were independent risk factors for CIN a relative increase de serum creatinine (O.R.: 3.5 [95% CI: 1.92-6.36], p < 0.01, 2.61 [95% CI: 1.14-6.03%], p < 0.05, respectively. Conclusions: We showed association between uses of intravenous injection contrast after computed tomography with acute injury renal, notably with diabetes and heart failure.

  2. The Future of Contrast-Enhanced Mammography.

    Science.gov (United States)

    Covington, Matthew F; Pizzitola, Victor J; Lorans, Roxanne; Pockaj, Barbara A; Northfelt, Donald W; Appleton, Catherine M; Patel, Bhavika K

    2018-02-01

    The purpose of this article is to discuss facilitators of and barriers to future implementation of contrast-enhanced mammography (CEM) in the United States. CEM provides low-energy 2D mammographic images analogous to digital mammography and contrast-enhanced recombined images that allow assessment of neovascularity similar to that offered by MRI. The utilization of CEM in the United States is currently low but could increase rapidly given the many potential indications for its clinical use.

  3. Contrast agent incompatibility with intravascular medications

    International Nuclear Information System (INIS)

    Irving, H.D.; Burbridge, B.E.

    1988-01-01

    In vitro and in vivo precipitation of iodinated contrast agents with commonly used medications have been reported. The intent of this in vitro study is to verify these reports and investigate other medications not previously tested. Contrast agents and medications were analyzed with a light spectrometer and observed for visible precipitates for up to 120 minutes. Previously reported incompatibilities were verified, and several new incompatibilities were discovered

  4. Contrast induced hyperthyroidism due to iodine excess

    OpenAIRE

    Mushtaq, Usman; Price, Timothy; Laddipeerla, Narsing; Townsend, Amanda; Broadbridge, Vy

    2009-01-01

    Iodine induced hyperthyroidism is a thyrotoxic condition caused by exposure to excessive iodine. Historically this type of hyperthyroidism has been described in areas of iodine deficiency. With advances in medicine, iodine induced hyperthyroidism has been observed following the use of drugs containing iodine—for example, amiodarone, and contrast agents used in radiological imaging. In elderly patients it is frequently difficult to diagnose and control contrast related hyperthyroidism, as most...

  5. Contrast-induced encephalopathy following cardiac catheterization.

    Science.gov (United States)

    Spina, Roberto; Simon, Neil; Markus, Romesh; Muller, David Wm; Kathir, Krishna

    2017-08-01

    To describe the epidemiology, pathophysiology, clinical presentation, and management of contrast-induced encephalopathy (CIE) following cardiac catheterization. CIE is an acute, reversible neurological disturbance directly attributable to the intra-arterial administration of iodinated contrast medium. The PubMed database was searched and all cases in the literature were retrieved and reviewed. 52 reports of CIE following cardiac catheterization were found. Encephalopathy, motor and sensory disturbances, vision disturbance, opthalmoplegia, aphasia, and seizures have been reported. Transient cortical blindness is the most commonly reported neurological syndrome, occurring in approximately 50% of cases. The putative mechanism involves disruption of the blood brain barrier and direct neuronal injury. Contrast-induced transient vasoconstriction has also been implicated. Symptoms typically appear within minutes to hours of contrast administration and resolve entirely within 24-48 hr. Risk factors may include hypertension, diabetes mellitus, renal impairment, the administration of large volumes of iodinated contrast, percutaneous coronary intervention or selective angiography of internal mammary grafts, and previous adverse reaction to iodinated contrast. Characteristic findings on cerebral imaging include cortical and sub-cortical contrast enhancement on computed tomography (CT). Imaging findings in CIE may mimic subarachnoid hemorrhage or cerebral ischemia; the Hounsfield scale on CT and the apparent diffusion coefficient on magnetic resonance imaging (MRI) are useful imaging tools in distinguishing these entities. In some cases, brain imaging is normal. Prognosis is excellent with supportive management alone. CIE tends to recur, although re-challenge with iodinated contrast without adverse effects has been documented. CIE is an important clinical entity to consider in the differential diagnosis of stroke following cardiac catheterization. Given that prognosis is

  6. Radiculography with reduced amounts of contrast medium

    International Nuclear Information System (INIS)

    Signorini, E.; Caputo, N.; Chiurulla, C.; Ciorba, E.; Pelliccioli, G.P.; Cianciulli, E.

    1984-01-01

    Because of the frequency and seriousness of side effects observed after radiculography, due to, among the other things, the amount of contrast medium, the authors describe a method that gives diagnostically satisfactory results using a low dose of contrast and a tangent-beam technique. Among 106 patients undergoing radiculography with a tangent-beam technique and Iopamidol, only 4 developed mild side effects, namely headache in three cases and headache with nausea in one. (Author)

  7. Contrast adaptation in the Limulus lateral eye

    OpenAIRE

    Valtcheva, Tchoudomira M.; Passaglia, Christopher L.

    2015-01-01

    Luminance and contrast adaptation are neuronal mechanisms employed by the visual system to adjust our sensitivity to light. They are mediated by an assortment of cellular and network processes distributed across the retina and visual cortex. Both have been demonstrated in the eyes of many vertebrates, but only luminance adaptation has been shown in invertebrate eyes to date. Since the computational benefits of contrast adaptation should apply to all visual systems, we investigated whether thi...

  8. Are ionic CAT contrast media still justifiable

    International Nuclear Information System (INIS)

    Witt, H.; Trempenau, B.; Dietz, G.

    1984-01-01

    The authors' clinical results revealed no statistically significant differences of tolerance between the two X-ray contrast media 'Ioxitalamat' and 'Ioglicinat'. Side-effects were found in 4.3% of the cases for both contrast media, a rate which is slightly below the one for urography. However, it must not be overlooked that patients exposed to certain risk faktors such as e.g. relative contraindications were as far as possible excluded from the study. (orig./WU) [de

  9. Microbubbles as contrast agent for in-line x-ray phase-contrast imaging

    International Nuclear Information System (INIS)

    Xi Yan; Zhao Jun; Tang Rongbiao; Wang Yujie

    2011-01-01

    In the present study, we investigated the potential of gas-filled microbubbles as contrast agents for in-line x-ray phase-contrast imaging (PCI) in biomedical applications. When imaging parameters are optimized, the microbubbles function as microlenses that focus the incoming x-rays to form bright spots, which can significantly enhance the image contrast. Since microbubbles have been shown to be safe contrast agents in clinical ultrasonography, this contrast-enhancement procedure for PCI may have promising utility in biomedical applications, especially when the dose of radiation is a serious concern. In this study, we performed both numerical simulations and ex vivo experiments to investigate the formation of the contrast and the effectiveness of microbubbles as contrast agents in PCI.

  10. Cue combination in a combined feature contrast detection and figure identification task.

    Science.gov (United States)

    Meinhardt, Günter; Persike, Malte; Mesenholl, Björn; Hagemann, Cordula

    2006-11-01

    Target figures defined by feature contrast in spatial frequency, orientation or both cues had to be detected in Gabor random fields and their shape had to be identified in a dual task paradigm. Performance improved with increasing feature contrast and was strongly correlated among both tasks. Subjects performed significantly better with combined cues than with single cues. The improvement due to cue summation was stronger than predicted by the assumption of independent feature specific mechanisms, and increased with the performance level achieved with single cues until it was limited by ceiling effects. Further, cue summation was also strongly correlated among tasks: when there was benefit due to the additional cue in feature contrast detection, there was also benefit in figure identification. For the same performance level achieved with single cues, cue summation was generally larger in figure identification than in feature contrast detection, indicating more benefit when processes of shape and surface formation are involved. Our results suggest that cue combination improves spatial form completion and figure-ground segregation in noisy environments, and therefore leads to more stable object vision.

  11. Contrast adaptation in the Limulus lateral eye.

    Science.gov (United States)

    Valtcheva, Tchoudomira M; Passaglia, Christopher L

    2015-12-01

    Luminance and contrast adaptation are neuronal mechanisms employed by the visual system to adjust our sensitivity to light. They are mediated by an assortment of cellular and network processes distributed across the retina and visual cortex. Both have been demonstrated in the eyes of many vertebrates, but only luminance adaptation has been shown in invertebrate eyes to date. Since the computational benefits of contrast adaptation should apply to all visual systems, we investigated whether this mechanism operates in horseshoe crab eyes, one of the best-understood neural networks in the animal kingdom. The spike trains of optic nerve fibers were recorded in response to light stimuli modulated randomly in time and delivered to single ommatidia or the whole eye. We found that the retina adapts to both the mean luminance and contrast of a white-noise stimulus, that luminance- and contrast-adaptive processes are largely independent, and that they originate within an ommatidium. Network interactions are not involved. A published computer model that simulates existing knowledge of the horseshoe crab eye did not show contrast adaptation, suggesting that a heretofore unknown mechanism may underlie the phenomenon. This mechanism does not appear to reside in photoreceptors because white-noise analysis of electroretinogram recordings did not show contrast adaptation. The likely site of origin is therefore the spike discharge mechanism of optic nerve fibers. The finding of contrast adaption in a retinal network as simple as the horseshoe crab eye underscores the broader importance of this image processing strategy to vision. Copyright © 2015 the American Physiological Society.

  12. Clinical evaluation of contrast-enhanced digital mammography and contrast enhanced tomosynthesis--Comparison to contrast-enhanced breast MRI.

    Science.gov (United States)

    Chou, Chen-Pin; Lewin, John M; Chiang, Chia-Ling; Hung, Bao-Hui; Yang, Tsung-Lung; Huang, Jer-Shyung; Liao, Jia-Bin; Pan, Huay-Ben

    2015-12-01

    To compare the diagnostic accuracy of contrast-enhanced digital mammography (CEDM) and contrast-enhanced tomosynthesis (CET) to dynamic contrast enhanced breast MRI (DCE-MRI) using a multireader-multicase study. Institutional review board approval and informed consents were obtained. Total 185 patients (mean age 51.3) with BI-RADS 4 or 5 lesions were evaluated before biopsy with mammography, tomosynthesis, CEDM, CET and DCE-MRI. Mediolateral-oblique and cranio-caudal views of the target breast CEDM and CET were acquired at 2 and 4 min after contrast agent injection. A mediolateral-oblique view of the non-target breast was taken at 6 min. Each lesion was scored with forced BI-RADS categories by three readers. Each reader interpreted lesions in the following order: mammography, tomosynthesis, CEDM, CET, and DCE-MRI during a single reading session. Histology showed 81 cancers and 144 benign lesions in the study. Of the 81 malignant lesions, 44% (36/81) were invasive and 56% (45/81) were non-invasive. Areas under the ROC curve, averaged for the 3 readers, were as follows: 0.897 for DCE-MRI, 0.892 for CET, 0.878 for CEDM, 0.784 for tomosynthesis and 0.740 for mammography. Significant differences in AUC were found between the group of contrast enhanced modalities (CEDM, CET, DCE-MRI) and the unenhanced modalities (all p0.05). CET and CEDM may be considered as an alternative modality to MRI for following up women with abnormal mammography. All three contrast modalities were superior in accuracy to conventional digital mammography with or without tomosynthesis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. Hepatobiliary contrast agents for contrast-enhanced MRI of the liver: properties, clinical development and applications

    International Nuclear Information System (INIS)

    Reimer, Peter; Schneider, Guenter; Schima, Wolfgang

    2004-01-01

    Hepatobiliary contrast agents with uptake into hepatocytes followed by variable biliary excretion represent a unique class of cell-specific MR contrast agents. Two hepatobiliary contrast agents, mangafodipir trisodium and gadobenate dimeglumine, are already clinically approved. A third hepatobiliary contrast agent, Gd-EOB-DTPA, is under consideration. The purpose of this review is to provide an overview on the properties, clinical development and application of these three hepatobiliary contrast agents. Bolus injectable paramagnetic hepatobiliary contrast agents combine established features of extracellular agents with the advantages of hepatocyte specificity. The detection and characterisation of focal liver disease appears to be improved compared to unenhanced MRI, MRI with unspecific contrast agents and contrast-enhanced CT. To decrease the total time spent by a patient in the MR scanner, it is advisable to administer the agent immediately after acquisition of unenhanced T1-w MRI. After infusion or bolus injection (with dynamic FS-T1-w 2D or 3D GRE) of the contrast agent, moderately and heavily T2w images are acquired. Post-contrast T1-w MRI is started upon completion of T2-w MRI for mangafodipir trisodium and Gd-EOB-DTPA as early as 20 min following injection, while gadobenate dimeglumine scans are obtained >60 min following injection. Post-contrast acquisition techniques with near isotropic 3D pulse sequences with fat saturation parallel the technical progress made by MSCT combined with an unparalleled improvement in tumour-liver contrast. The individual decision that hepatobiliary contrast agent one uses is partly based on personal preferences. No comparative studies have been conducted comparing the advantages or disadvantages of all three agents directly against each other. (orig.)

  14. Field strength and dose dependence of contrast enhancement by gadolinium-based MR contrast agents

    International Nuclear Information System (INIS)

    Rinck, P.A.; Muller, R.N.

    1999-01-01

    The relaxivities r 1 and r 2 of magnetic resonance contrast agents and the T 1 relaxation time values of tissues are strongly field dependent. We present quantitative data and simulations of different gadolinium-based extracellular fluid contrast agents and the modulation of their contrast enhancement by the magnetic field to be able to answer the following questions: How are the dose and field dependences of their contrast enhancement? Is there an interrelationship between dose and field dependence? Should one increase or decrease doses at specific fields? Nuclear magnetic relaxation dispersion data were acquired for the following contrast agents: gadopentetate dimeglumine, gadoterate meglumine, gadodiamide injection, and gadoteridol injection, as well as for several normal and pathological human tissue samples. The magnetic field range stretched from 0.0002 to 4.7 T, including the entire clinical imaging range. The data acquired were then fitted with the appropriate theoretical models. The combination of the diamagnetic relaxation rates (R 1 = 1/T 1 and R 2 = 1/T 2 ) of tissues with the respective paramagnetic contributions of the contrast agents allowed the prediction of image contrast at any magnetic field. The results revealed a nearly identical field and dose-dependent increase of contrast enhancement induced by these contrast agents within a certain dose range. The target tissue concentration (TTC) was an important though nonlinear factor for enhancement. The currently recommended dose of 0.1 mmol/kg body weight seems to be a compromise close to the lower limits of diagnostically sufficient contrast enhancement for clinical imaging at all field strengths. At low field contrast enhancement might be insufficient. Adjustment of dose or concentration, or a new class of contrast agents with optimized relaxivity, would be a valuable contribution to a better diagnostic yield of contrast enhancement at all fields. (orig.)

  15. Morphological rational operator for contrast enhancement.

    Science.gov (United States)

    Peregrina-Barreto, Hayde; Herrera-Navarro, Ana M; Morales-Hernández, Luis A; Terol-Villalobos, Iván R

    2011-03-01

    Contrast enhancement is an important task in image processing that is commonly used as a preprocessing step to improve the images for other tasks such as segmentation. However, some methods for contrast improvement that work well in low-contrast regions affect good contrast regions as well. This occurs due to the fact that some elements may vanish. A method focused on images with different luminance conditions is introduced in the present work. The proposed method is based on morphological transformations by reconstruction and rational operations, which, altogether, allow a more accurate contrast enhancement resulting in regions that are in harmony with their environment. Furthermore, due to the properties of these morphological transformations, the creation of new elements on the image is avoided. The processing is carried out on luminance values in the u'v'Y color space, which avoids the creation of new colors. As a result of the previous considerations, the proposed method keeps the natural color appearance of the image.

  16. Nonimmediate hypersensitivity reactions to iodinated contrast media.

    Science.gov (United States)

    Gómez, Enrique; Ariza, Adriana; Blanca-López, Natalia; Torres, Maria J

    2013-08-01

    To provide a detailed analysis of the latest findings on the mechanisms underlying the nonimmediate reactions to iodinated contrast media and comment on the recent advances in diagnosis, focusing on the roles of the skin test, drug provocation test (DPT), and lymphocyte transformation test (LTT). Several studies have reported new findings supporting an important role for T-lymphocytes in the nonimmediate reactions to iodinated contrast media. The LTT has been used as an in-vitro tool for diagnosis, but with variable results. However, the inclusion of autologous monocyte-derived dendritic cells as professional antigen-presenting cells has improved the sensitivity of this test. Regarding in-vivo diagnosis, although skin testing has been routine, it has now been shown that its sensitivity and negative predictive value are low. Recent studies have demonstrated that the DPT is a well tolerated and useful procedure that is necessary to confirm the diagnosis of nonimmediate hypersensitivity reactions to iodinated contrast media. Nonimmediate reactions to contrast media are usually T-cell mediated. Diagnosis is based on skin testing, although its sensitivity and negative predictive value are not optimal. Consequently, drug provocation testing is often needed to confirm the diagnosis and also to seek alternative contrast media that can be tolerated.

  17. Contrast agent choice for intravenous coronary angiography

    International Nuclear Information System (INIS)

    Zeman, H.D.; Siddons, D.P.

    1989-01-01

    The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with monochromatic synchrotron radiation x-rays and an iodine containing contrast agent at the Stanford Synchrotron Radiation Laboratory have shown that such an intravenous angiography procedure would be possible with an adequately intense monochromatic x-ray source. Because of the size and cost of synchrotron radiation facilities it would be desirable to make the most efficient use of the intensity available, while reducing as much as possible the radiation dose experienced by the patient. By choosing contrast agents containing elements with a higher atomic number than iodine, it is possible to both improve the image quality and reduce the patient radiation dose, while using the same synchrotron source. By using Si monochromator crystals with a small mosaic spread, it is possible to increase the x-ray flux available for imaging by over an order of magnitude, without any changes in the storage ring or wiggler magnet. The most critical imaging task for intravenous coronary angiography utilizing synchrotron radiation x-rays is visualizing a coronary artery through the left ventricle or aorta which also contains a contrast agent. Calculations have been made of the signal to noise ratio expected for this imaging task for various contrast agents with atomic numbers between that of iodine and bismuth

  18. Use of contrast agents for liver MRI

    International Nuclear Information System (INIS)

    Ward, Janice

    2007-01-01

    Contrast-enhanced MRI is recognised as one of the most accurate imaging methods for investigating diseases of the liver. Uniquely several different types of contrast agents are available for liver MRI. They can be divided into non-specific extracellular fluid space (ECF), hepatocyte specific and reticulo-endothelial system (RES) specific agents. They are used to improve the detection of focal liver lesions by increasing normal-abnormal tissue contrast and to assist in lesion characterisation by demonstrating tissue perfusion and cellular function. ECF-gadolinium (Gd) chelates have been widely used in abdominal MRI for many years. They provide valuable information regarding the vascularisation and perfusion characteristics of lesions and assist in lesion detection, particularly of hypervascular lesions. The hepatocyte and RES-specific agents further improve lesion detection, provide important functional information and allow the distinction between hepatocellular and non-hepatocellular tumours. This article describes the different MR contrast agents and discusses their current status for diagnosing focal liver lesions. The importance of optimised technique and appropriate selection of contrast agent is emphasised

  19. Visibility of minute objects with low contrast

    International Nuclear Information System (INIS)

    Sato, Nobuo

    1982-01-01

    Minimum perceptible contrast was obtained with a penetrameter made of aluminum plates, in which 40 very small holes were perforated. An object can be seen when its contrast exceeds the minimum perceptible contrast. Visual threshold contrast ratio offers minimum perceptible diameter (MPD) which is theoretically obtained from an image contrast corresponding to the technique applied. The MPDs were obtained prior to experiment as a function of system speed, beam quality, exposure range and magnification, which resulted in a reasonable agreement with the experimental results. The visibility of small dot-like objects depends on the granularity as its threshold is governed by the surrounding grainy noise. However it was revealed that MTF was as important as granularity. Dot and lineshaped objects were simulated with small glass beads and nylon fibrils, respectively, in order to make ROC analysis on the different radiographic techniques with a CGR Senograph 500T mammographic unit. The 1.5X magnification technique showed the largest advantage on phantom work basis, but clinical evaluation showed the different weight of the affecting physical factors. The results of ROC analysis were extended to entropy analysis. The visibility in actual mammography depends upon the acutance of images as Xeroradiography proved. (Kako, I.)

  20. Contrast enhanced ultrasound of sentinel lymph nodes

    Directory of Open Access Journals (Sweden)

    XinWu Cui

    2013-03-01

    Full Text Available Sentinel lymph nodes are the first lymph nodes in the region that receive lymphatic drainage from a primary tumor. The detection or exclusion of sentinel lymph node micrometastases is critical in the staging of cancer, especially breast cancer and melanoma because it directly affects patient’s prognosis and surgical management. Currently, intraoperative sentinel lymph node biopsies using blue dye and radioisotopes are the method of choice for the detection of sentinel lymph node with high identification rate. In contrast, conventional ultrasound is not capable of detecting sentinel lymph nodes in most cases. Contrast enhanced ultrasound with contrast specific imaging modes has been used for the evaluation and diagnostic work-up of peripherally located suspected lymphadenopathy. The method allows for real-time analysis of all vascular phases and the visualization of intranodal focal “avascular” areas that represent necrosis or deposits of neoplastic cells. In recent years, a number of animal and human studies showed that contrast enhanced ultrasound can be also used for the detection of sentinel lymph node, and may become a potential application in clinical routine. Several contrast agents have been used in those studies, including albumin solution, hydroxyethylated starch, SonoVue®, Sonazoid® and Definity®. This review summarizes the current knowledge about the use of ultrasound techniques in detection and evaluation of sentinel lymph node.

  1. Supporting young people living with cancer to tell their stories in ways that make them stronger: The Beads of Life approach.

    Science.gov (United States)

    Portnoy, Sara; Girling, Isabella; Fredman, Glenda

    2016-04-01

    This article describes the 'Beads of Life' approach--a five-part methodology informed by narrative therapy to enable children and young people to make sense of their cancer journey in ways that make them stronger. Young people are invited to use beads as prompts to tell preferred stories of their identity to create a safe place to stand from which to story their cancer journey. The approach positions young people as experts in their lives. It aims to change their relationship with cancer to reduce its negative impact on life by lessening isolation. By enabling medical staff to get to know the young person apart from the cancer, this approach aims to create hope for the future and improve quality of care. © The Author(s) 2015.

  2. CDC'S Testing Makes Us Stronger (TMUS) Campaign: Was Campaign Exposure Associated With HIV Testing Behavior Among Black Gay and Bisexual Men?

    Science.gov (United States)

    Habarta, Nancy; Boudewyns, Vanessa; Badal, Hannah; Johnston, Jennie; Uhrig, Jennifer; Green, Donata; Ruddle, Paul; Rosenthal, Jacqueline; Stryker, Jo Ellen

    2017-06-01

    This study assessed exposure among Black gay, bisexual, and other men who have sex with men (BMSM) to a communication campaign, Testing Makes Us Stronger (TMUS), and its association with HIV testing to determine campaign effectiveness. Data from an online survey (N = 3,105) were analyzed using propensity score weight-adjusted logistic regression to examine the effect of exposure on HIV testing. Among BMSM aged 18-44 (n = 702), 43.2% reported TMUS exposure. The majority of those exposed were aged 25-34 (54%), HIV-negative (65%), and had some college education (87%). TMUS exposure was associated with reported increased HIV testing behaviors at 6- and 12-month frequencies. Communication campaigns with clear implementation strategies, focused objectives, and online and event presence can be associated with longer-term outcomes such as HIV testing.

  3. Moderate Contrast in the Evaluation of Paintings Is Liked More but Remembered Less than High Contrast

    Directory of Open Access Journals (Sweden)

    Katinka Dijkstra

    2017-09-01

    Full Text Available Many visual aspects of paintings, as well as exposure to art and cultural norms, contribute to the aesthetic evaluation of paintings. The current study looked at heightened visual contrast as an important factor in the appreciation of paintings. Participants evaluated abstract digitized paintings that were manipulated in contrast for an appreciation task and were later presented with these paintings in a memory task. The results indicated that for art appreciation, a moderate increase in contrast resulted in the highest appreciation for paintings whereas recognition memory was better for paintings with a higher increase in contrast. These results replicate earlier findings with regard to the role of contrast in aesthetic perception and extend these findings by demonstrating a surprising different effect of contrast manipulation for recognition memory. Confidence with which memory decisions were made was in line with art appreciation decisions not memory performance.

  4. Elevated arousal levels enhance contrast perception.

    Science.gov (United States)

    Kim, Dongho; Lokey, Savannah; Ling, Sam

    2017-02-01

    Our state of arousal fluctuates from moment to moment-fluctuations that can have profound impacts on behavior. Arousal has been proposed to play a powerful, widespread role in the brain, influencing processes as far ranging as perception, memory, learning, and decision making. Although arousal clearly plays a critical role in modulating behavior, the mechanisms underlying this modulation remain poorly understood. To address this knowledge gap, we examined the modulatory role of arousal on one of the cornerstones of visual perception: contrast perception. Using a reward-driven paradigm to manipulate arousal state, we discovered that elevated arousal state substantially enhances visual sensitivity, incurring a multiplicative modulation of contrast response. Contrast defines vision, determining whether objects appear visible or invisible to us, and these results indicate that one of the consequences of decreased arousal state is an impaired ability to visually process our environment.

  5. Contrast Enhanced Spectral Mammography: A Review.

    Science.gov (United States)

    Patel, Bhavika K; Lobbes, M B I; Lewin, John

    2018-02-01

    Contrast-enhanced spectral mammography (CESM) provides low-energy 2D mammographic images comparable to standard digital mammography and a post-contrast recombined image to assess tumor neovascularity similar to magnetic resonance imaging (MRI). The utilization of CESM in the United States is currently low but could increase rapidly given many potential indications for clinical use. This article discusses historical background and literature review of indications and diagnostic accuracy of CESM to date. CESM is a growing technique for breast cancer detection and diagnosis that has levels of sensitivity and specificity on par with contrast-enhanced breast MRI. Because of its similar performance and ease of implementation, CESM is being adopted for multiple indications previously reserved for MRI, such as problem-solving, disease extent in newly diagnosed patients, and evaluating the treatment response of neoadjuvant chemotherapy. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Reconstruction methods for phase-contrast tomography

    Energy Technology Data Exchange (ETDEWEB)

    Raven, C.

    1997-02-01

    Phase contrast imaging with coherent x-rays can be distinguished in outline imaging and holography, depending on the wavelength {lambda}, the object size d and the object-to-detector distance r. When r << d{sup 2}{lambda}, phase contrast occurs only in regions where the refractive index fastly changes, i.e. at interfaces and edges in the sample. With increasing object-to-detector distance we come in the area of holographic imaging. The image contrast outside the shadow region of the object is due to interference of the direct, undiffracted beam and a beam diffracted by the object, or, in terms of holography, the interference of a reference wave with the object wave. Both, outline imaging and holography, offer the possibility to obtain three dimensional information of the sample in conjunction with a tomographic technique. But the data treatment and the kind of information one can obtain from the reconstruction is different.

  7. X-ray phase-contrast imaging

    Science.gov (United States)

    Endrizzi, Marco

    2018-01-01

    X-ray imaging is a standard tool for the non-destructive inspection of the internal structure of samples. It finds application in a vast diversity of fields: medicine, biology, many engineering disciplines, palaeontology and earth sciences are just few examples. The fundamental principle underpinning the image formation have remained the same for over a century: the X-rays traversing the sample are subjected to different amount of absorption in different parts of the sample. By means of phase-sensitive techniques it is possible to generate contrast also in relation to the phase shifts imparted by the sample and to extend the capabilities of X-ray imaging to those details that lack enough absorption contrast to be visualised in conventional radiography. A general overview of X-ray phase contrast imaging techniques is presented in this review, along with more recent advances in this fast evolving field and some examples of applications.

  8. Contrast media safety-an update

    DEFF Research Database (Denmark)

    Thomsen, Henrik S

    2011-01-01

    The value of contrast agents has for long been documented by their common daily use in imaging departments worldwide. In principle, they should be injected and leave the body immediately after use in the same condition or undergo natural metabolism without making any harm to the patient. However......, this is not the case. It is of utmost importance to reduce the prevalence to as close as possible to zero. This can be done by identifying the patients at risk before administration of contrast agents. For acute non-renal adverse reactions, it is also important to be prepared for treating them instantly. The current...... review is a short state of the art regarding adverse reactions to contrast agents....

  9. Letter contrast sensitivity function of the eye.

    Science.gov (United States)

    Liou, H L; Brennan, N A

    1998-06-01

    To provide empirical data of letter CSF for various levels of defocus under controlled conditions of luminance and age. Corrected distance visual acuities were tested at different levels of contrast and defocus. An experiment was conducted using the Medmont visual acuity tester on 10 young subjects and under normal room lighting. Empirical data of visual acuity were obtained for 7 levels of contrast (5, 10, 15, 25, 40, 60, 80%) and defocus levels of 0, +1 and +2D. A mathematical model was derived (R2=0.995) and this can be used to estimate visual acuity at various contrast levels for defocus of < or =+2D. This information is useful for the clinician as normative data and for further development of optical models to predict visual performance of the eye.

  10. Non-radiological contrast agents (MRI)

    International Nuclear Information System (INIS)

    Bonnemain, B.; Lautrou, J.; Meyer, D.; Doucet, D.

    1987-01-01

    Over the past few years, extensive research has been carried out in an attempt to develop contrast agents that could help improve both the performance (acquisition times) and the diagnostic efficacy of Magnetic Resonance Imaging (MRI) techniques. On the basis of physicochemical and pharmacological criteria discussed in this presentation, a few efficacious, well-tolerated compounds could be developed. Two of them, the gadolinium complexes Gd-DOTA and Gd-DTPA, are currently being tried in man. This first generation of contrast agents, which are aspecific markers of the intravascular space, has been shown to have good diagnostic potential in conventional MRI procedures. The diagnostic contribution of these contrast agents will probably be a most essential factor in new MRI techniques using low field strengh or fast imaging sequences [fr

  11. Contrast agent choice for intravenous coronary angiography

    International Nuclear Information System (INIS)

    Zeman, H.D.; Siddons, D.P.

    1990-01-01

    The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with monochromatic synchrotron radiation X-rays and an iodine-containing contrast agent at the Stanford Synchrotron Radiation Laboratory have shown that such an intravenous angiography procedure would be possible with an adequately intense monochromatic X-ray source. Because of the size and cost of synchrotron radiation facilities it would be desirable to make the most efficient use of the intensity available, while reducing as much as possible the radiation dose experienced by the patient. By choosing contrast agents containing elements with a higher atomic number than iodine, it is possible to both improve the image quality and reduce the patient radiation dose, while using the same synchrotron radiation source. By using Si monochromator crystals with a small mosaic spread, it is possible to increase the X-ray flux available for imaging by over an order of magnitude, without any changes in the storage ring or wiggler magnet. The most critical imaging task for intravenous coronary angiography utilizing synchrotron radiation X-rays is visualizing a coronary artery through the left ventricle or aorta which also contain contrast agent. Calculations have been made of the signal to noise ratio expected for this imaging task for various contrast agents with atomic numbers between that of iodine and bismuth. The X-ray energy spectrum of the X-17 superconduction wiggler beam line at the National Synchrotron Light Source at Brookhaven National Laboratory has been used for these calculations. Both perfect Si crystals and Si crystals with a small mosaic spread are considered as monochromators. Contrast agents containing Gd or Yb seem to have about the optimal calculated signal to noise ratio. (orig./HSI)

  12. Applications of energy loss contrast STIM

    International Nuclear Information System (INIS)

    Bench, G.; Saint, A.; Legge, G.J.F.; Cholewa, M.

    1992-01-01

    Scanning Transmission Ion Microscopy (STIM) with energy loss contrast is a quantitative imaging technique. A focussed MeV ion microbeam is scanned over the sample and measured energy losses of residual ions at each beam location are used to provide the contrast in the image. The technique is highly efficient as almost every ion carries useful information from which quantitative data can be obtained. The high efficiency of data collection at present necessitates the use of small beam currents. Therefore small apertures can be used and fine spatial resolution can be achieved. High efficiency also makes it possible to collect large data sets for high definition imaging with a small radiation dose. Owing to the simple relationship between energy loss and areal density, STIM with energy loss contrast can provide a quantitative image that can be used to obtain areal density information on the sample. These areal density maps can be used not only to provide a high resolution image of the sample but also to normalise Particle Induced Xray Emission (PIXE) data. The small radiation dose required to form these areal density maps also allows one to use STIM with energy loss contrast to quantitatively monitor ion beam induced specimen changes caused by higher doses and dose rates used in other microanalytical techniques. STIM with energy loss contrast also provides the possibility of stereo imaging and ion microtomography. STIM has also been used in conjunction with channeling to explore transmission channeling in thin crystals. This paper will discuss these applications of STIM with energy loss contrast and look at further developments from them

  13. Relationship Between Collateral Status, Contrast Transit, and Contrast Density in Acute Ischemic Stroke.

    Science.gov (United States)

    Kawano, Hiroyuki; Bivard, Andrew; Lin, Longting; Spratt, Neil J; Miteff, Ferdinand; Parsons, Mark W; Levi, Christopher R

    2016-03-01

    Collateral circulation is recognized to influence the life expectancy of the ischemic penumbra in acute ischemic stroke. The best method to quantify collateral status on acute imaging is uncertain. We aimed to determine the relationship between visual collateral status, quantitative collateral assessments, baseline computed tomographic perfusion measures, and tissue outcomes on follow-up imaging. Sixty-six consecutive patients with acute ischemic stroke clinically eligible for recanalization therapy and with M1 or M2 middle cerebral artery occlusion were evaluated. We compared the visual collateral scoring with measures of contrast peak time delay and contrast peak density. We also compared these measures for their ability to predict perfusion lesion and infarct core volumes, final infarct, and infarct growth. Shorter contrast peak time delay (P=0.041) and higher contrast peak density (P=0.002) were associated with good collateral status. Shorter contrast peak time delay correlated with higher contrast peak density (β=-4.413; P=0.037). In logistic regression analysis after adjustment for age, sex, onset-computed tomographic time, and occlusion site, higher contrast peak density was independently associated with good collateral status (P=0.009). Multiple regression analysis showed that higher contrast peak density was an independent predictor of smaller perfusion lesion volume (P=0.029), smaller ischemic core volume (P=0.044), smaller follow-up infarct volume (P=0.005), and smaller infarct growth volume (P=0.010). Visual collateral status, contrast peak density, and contrast peak time delay were inter-related, and good collateral status was strongly associated with contrast peak density. Contrast peak density in collateral vessel may be an important factor in tissue fate in acute ischemic stroke. © 2016 American Heart Association, Inc.

  14. Safety of contrast media. Focus on contrast-induced nephropathy (CIN)

    International Nuclear Information System (INIS)

    Kuwatsuru, Ryohei

    2011-01-01

    Despite advances in imaging diagnosis, contrast media still play an important role in diagnosing the existence of the disease, demonstrating the extent of disease, and determining the perfusion of the disease, which is important to make a differential diagnosis. However, the administration of contrast media may cause contrast-induced nephropathy (CIN), especially in patients with renal impairment. It is estimated that 20-30% of patients with renal impairment who received contrast media develop CIN. Though the precise cause of CIN currently remains unknown, almost all injected contrast media are excreted through the kidney and the effects of contrast media on the kidney are easily understood. As CIN is the most common cause of death due to complications after receiving contrast media, prevention of CIN is important. There are several known risk factors for CIN. Patients with renal impairment, diabetes mellitus, and dehydration are at high risk for CIN. Furthermore, a high osmolar contrast media, excessive amount of contrast media, and ionic contrast media are also risk factors for CIN. CIN can be prevented in several ways. Certain drugs seem to be useful to prevent CIN, while others are harmful. Hydration is useful to prevent CIN, although there is no widely acceptable hydration method to prevent CIN. Both sodium bicarbonate and N-acetylcysteine are promising candidates for prevention of CIN. There are few reports to study CIN after intravenous administration, although reports of CIN after percutaneous cardiac intervention (PCI) and angiography are well recognized. In clinical situations, intravenous administration of contrast media is common. Therefore, a study of CIN after intravenous administration of contrast media should be performed. (author)

  15. Global contrast based salient region detection

    KAUST Repository

    Cheng, Ming-Ming

    2011-08-25

    Reliable estimation of visual saliency allows appropriate processing of images without prior knowledge of their contents, and thus remains an important step in many computer vision tasks including image segmentation, object recognition, and adaptive compression. We propose a regional contrast based saliency extraction algorithm, which simultaneously evaluates global contrast differences and spatial coherence. The proposed algorithm is simple, efficient, and yields full resolution saliency maps. Our algorithm consistently outperformed existing saliency detection methods, yielding higher precision and better recall rates, when evaluated using one of the largest publicly available data sets. We also demonstrate how the extracted saliency map can be used to create high quality segmentation masks for subsequent image processing.

  16. Negative contrast peritoneography in the horse

    International Nuclear Information System (INIS)

    Lloyd, K.C.K.; Kerr, L.Y.; Meagher, D.M.; Baker, T.W.; Kurpershoek, C.J.

    1989-01-01

    A method of negative contrast peritoneography using CO 2 peritoneal insufflation technique was investigated in adult horses. Radiographic visualization of anatomic structures in the dorsal abdomen, including the kidneys, portions of the spleen and liver, dorsal stomach and mesenteric root region, was enhanced. Visualization of ventral abdominal structures was not enhanced. Negative contrast peritoneography allowed reduction in the radiographic technique from 140 kVp and 40 mAs before insufflation to 100 kVp and 5–10 mAs following insufflation. The technique was easily and safely performed with minimal patient discomfort and risk

  17. Dynamic contrast enhanced ultrasound for therapy monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, John M. [Department of Medical Biophysics, University of Toronto, Toronto, ON (Canada); Williams, Ross [Imaging Research, Sunnybrook Research Institute, Toronto, ON (Canada); Tremblay-Darveau, Charles; Sheeran, Paul S. [Department of Medical Biophysics, University of Toronto, Toronto, ON (Canada); Milot, Laurent [Department of Medical Imaging, University of Toronto, Toronto, ON (Canada); Bjarnason, Georg A. [Department of Medical Oncology, University of Toronto, and Sunnybrook Odette Cancer Centre, Toronto, ON (Canada); Burns, Peter N., E-mail: burns@sri.utoronto.ca [Department of Medical Biophysics, University of Toronto, Toronto, ON (Canada); Imaging Research, Sunnybrook Research Institute, Toronto, ON (Canada); Department of Medical Imaging, University of Toronto, Toronto, ON (Canada)

    2015-09-15

    Quantitative imaging is a crucial component of the assessment of therapies that target the vasculature of angiogenic or inflamed tissue. Dynamic contrast-enhanced ultrasound (DCE-US) using microbubble contrast offers the advantages of being sensitive to perfusion, non-invasive, cost effective and well suited to repeated use at the bedside. Uniquely, it employs an agent that is truly intravascular. This papers reviews the principles and methodology of DCE-US, especially as applied to anti-angiogenic cancer therapies. Reproducibility is an important attribute of such a monitoring method: results are discussed. More recent technical advances in parametric and 3D DCE-US imaging are also summarised and illustrated.

  18. Laser projection using generalized phase contrast

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin; Rodrigo, Peter John

    2007-01-01

    is introduced. An arbitrary phase shift filter eliminates the need for high-frequency modulation and conjugate phase encoding. This lowers device performance requirements and allows practical implementation with currently available dynamic spatial light modulators. (c) 2007 Optical Society of America.......We demonstrate experimental laser projection of a gray-level photographic image with 74% light efficiency using the generalized phase contrast (GPC) method. In contrast with a previously proposed technique [Alonzo et al., New J. Phys. 9, 132 (2007)], a new approach to image construction via GPC...

  19. Contrast optimization in multiphase arterial spin labeling

    International Nuclear Information System (INIS)

    Paiva, Fernando F.; Paschoal, Andre M.; Tovar-Moll, Fernanda; Moll, Jorge

    2013-01-01

    Multiphase ASL is an effective way to overcome the regional variation of the transit time that difficult the estimation of perfusion values. However, with conventional multiple phases ASL techniques, the ASL contrast at later phases is impaired due to repeated application of excitation pulses and longitudinal relaxation making it difficult to evaluate the tissue perfusion in regions where the transit time is longer. In the present study, we show an improvement of the acquisition scheme by exploring a modulation on the flip angle of the MR acquisition to keep the ASL contrast constant over multiple phases. (author)

  20. Hypersensitivity to contrast media and dyes.

    Science.gov (United States)

    Brockow, Knut; Sánchez-Borges, Mario

    2014-08-01

    This article updates current knowledge on hypersensitivity reactions to diagnostic contrast media and dyes. After application of a single iodinated radiocontrast medium (RCM), gadolinium-based contrast medium, fluorescein, or a blue dye, a hypersensitivity reaction is not a common finding; however, because of the high and still increasing frequency of those procedures, patients who have experienced severe reactions are nevertheless frequently encountered in allergy departments. Evidence on allergologic testing and management is best for iodinated RCM, limited for blue dyes, and insufficient for fluorescein. Skin tests can be helpful in the diagnosis of patients with hypersensitivity reactions to these compounds. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Global contrast based salient region detection

    KAUST Repository

    Cheng, Ming-Ming; Zhang, Guo-Xin; Mitra, Niloy J.; Huang, Xiaolei; Hu, Shi-Min

    2011-01-01

    Reliable estimation of visual saliency allows appropriate processing of images without prior knowledge of their contents, and thus remains an important step in many computer vision tasks including image segmentation, object recognition, and adaptive compression. We propose a regional contrast based saliency extraction algorithm, which simultaneously evaluates global contrast differences and spatial coherence. The proposed algorithm is simple, efficient, and yields full resolution saliency maps. Our algorithm consistently outperformed existing saliency detection methods, yielding higher precision and better recall rates, when evaluated using one of the largest publicly available data sets. We also demonstrate how the extracted saliency map can be used to create high quality segmentation masks for subsequent image processing.

  2. Post-traumatic contrast enhancing brain lesion

    International Nuclear Information System (INIS)

    Kim, Dae Jung; Kim, Hyun Sook; Jeong, Min Sun; Kim, Deok Ryeong; Cho, Young Kwon; Choi, Yun Sun

    2014-01-01

    Only a few studies have been reported on the MR contrast enhancement and the apparent diffusion coefficient (ADC) findings of the post-traumatic lesion of the brain. We report a case of the venous ischemia in the left frontal lobe observed in the MRI obtained one day after the incidence of trauma. Considering the presented slight increase in the ADC, the vasogenic edema was thought to be the major mechanism of the venous ischemia and excitotoxic injury. In spite of a slight increase in the ADC, the hyperintensity in the diffusion weighted imaging and contrast-enhanced areas eventually changed into hemorrhagic lesions.

  3. Post-traumatic contrast enhancing brain lesion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Jung; Kim, Hyun Sook; Jeong, Min Sun; Kim, Deok Ryeong; Cho, Young Kwon; Choi, Yun Sun [Eulji Hospital, Eulji University College of Medicine, Seoul (Korea, Republic of)

    2014-10-15

    Only a few studies have been reported on the MR contrast enhancement and the apparent diffusion coefficient (ADC) findings of the post-traumatic lesion of the brain. We report a case of the venous ischemia in the left frontal lobe observed in the MRI obtained one day after the incidence of trauma. Considering the presented slight increase in the ADC, the vasogenic edema was thought to be the major mechanism of the venous ischemia and excitotoxic injury. In spite of a slight increase in the ADC, the hyperintensity in the diffusion weighted imaging and contrast-enhanced areas eventually changed into hemorrhagic lesions.

  4. Double contrast barium meal and acetylcysteine

    International Nuclear Information System (INIS)

    Kinnunen, J.; Pietilae, J.; Ahovuo, J.; Mankinen, P.; Tervahartiala, P.

    1989-01-01

    In a prospective double blind study, acetylcysteine, a local and systemic respiratory tract mucolytic agent, or a placebo, were given to 100 patients prior to a double contrast barium meal to decrease the gastric mucus viscosity and to make the mucus layer thinner, in order to permit barium to outline the furrows surrounding the areae gastricae instead of the overlying thick mucus. However, acetylcysteine failed to improve either visualization of the areae gastricae or the general quality of the double contrast barium meal. (orig.)

  5. Contrastive hierarchies, privative features, and Portuguese vowels

    Directory of Open Access Journals (Sweden)

    Joaquim Brandão de Carvalho

    2011-01-01

    Full Text Available Dresher’s (2009 Contrastive hierarchy theory (CHT is intended to provide a unified account of both sides of phonological primes: contrastivity and behaviour. This article explores the point and the possibility of extending CHT, which is based on binary features, to a system of monovalent elements that is much indebted to Schane’s (1984 Particle Phonology. It shows how several aspects of the phonology of European Portuguese nuclei that seem prima facie independent from one another – such as reduction patterns and the inventory of diphthongs and nasal vowels – are constrained by element hierarchy, and, thus, receive a unitary account.

  6. Contrast-Enhanced Ultrasound in Vascular Surgery

    DEFF Research Database (Denmark)

    Bredahl, Kim; Mestre, Xavier Marti; Coll, Ramon Vila

    2017-01-01

    modalities. Ultrasound has only challenged these methods in assessment of carotid disease, aortic aneurysms, venous insufficiency, and thromboembolism and in surveillance of in situ bypasses. These practice patterns may change with the introduction of second-generation ultrasound contrast agents which...... are easy to use, manageable, and safe. This topical review attempts to summarize and highlight the current evidence and future prospects for contrast-enhanced ultrasound in vascular surgery, with a particular focus on opportunities in carotid and lower limb arteriosclerotic disease and surveillance after...

  7. Dynamic contrast enhanced MRI for perfusion quantification

    DEFF Research Database (Denmark)

    Andersen, Irene Klærke

    2002-01-01

    Magnetic resonance imaging, during bolus passage of a paramagnetic contrast agent, is used world-wide to obtain parameters that reflect the pathological state of tissue. Abnormal perfusion occurs in diseases such as stoke and tumour. Consequently, perfusion quantication could have signi cant...... clinical value both in diagnosis and treatment of such pathologies. One approach for perfusion quanti cation involves using the contrast mechanism that a ects the transverse relaxation rates of the magnetization, R2 or R 2 , since this provides the most pronounced effect. However, the linearity between...

  8. The double contrast examination of the colon

    International Nuclear Information System (INIS)

    Welin, S.; Welin, G.

    1980-01-01

    The double contrast method has been modified in order to get a more detailed picture of the mucous membrane of the colon. The method has been employed at Malmoe hospital since 1953. The method and its diagnostic application in cases of adenoids, villiferous tumours, diverticula, Crohn's disease, ulcerating colitis, and deformation of the rectum/sigma junction due to external endometriosis and peritoneal carcinosis are described. The diagnostic values of the double contrast method and colposcopy/biopsy of the colon are compared. The two methods are found to be complementary. (MG) [de

  9. Exogenous contrast agents for thermoacoustic imaging: An investigation into the underlying sources of contrast

    International Nuclear Information System (INIS)

    Ogunlade, Olumide; Beard, Paul

    2015-01-01

    Purpose: Thermoacoustic imaging at microwave excitation frequencies is limited by the low differential contrast exhibited by high water content tissues. To overcome this, exogenous thermoacoustic contrast agents based on gadolinium compounds, iron oxide, and single wall carbon nanotubes have previously been suggested and investigated. However, these previous studies did not fully characterize the electric, magnetic, and thermodynamic properties of these agents thus precluding identification of the underlying sources of contrast. To address this, measurements of the complex permittivity, complex permeability, DC conductivity, and Grüneisen parameter have been made. These measurements allowed the origins of the contrast provided by each substance to be identified. Methods: The electric and magnetic properties of the contrast agents were characterized at 3 GHz using two rectangular waveguide cavities. The DC conductivity was measured separately using a conductivity meter. Thermoacoustic signals were then acquired and compared to those generated in water. Finally, 3D electromagnetic simulations were used to decouple the different contributions to the absorbed power density. Results: It was found that the gadolinium compounds provided appreciable electric contrast but not originating from the gadolinium itself. The contrast was either due to dissociation of the gadolinium salt which increased ionic conductivity or its nondissociated polar fraction which increased dielectric polarization loss or a combination of both. In addition, very high concentrations were required to achieve appreciable contrast, to the extent that the Grüneisen parameter increased significantly and became a source of contrast. Iron oxide particles were found to produce low but measurable dielectric contrast due to dielectric polarization loss, but this is attributed to the coating of the particles not the iron oxide. Single wall carbon nanotubes did not provide measurable contrast of any type

  10. Contextual effects on perceived contrast: figure-ground assignment and orientation contrast.

    Science.gov (United States)

    Self, Matthew W; Mookhoek, Aart; Tjalma, Nienke; Roelfsema, Pieter R

    2015-02-02

    Figure-ground segregation is an important step in the path leading to object recognition. The visual system segregates objects ('figures') in the visual scene from their backgrounds ('ground'). Electrophysiological studies in awake-behaving monkeys have demonstrated that neurons in early visual areas increase their firing rate when responding to a figure compared to responding to the background. We hypothesized that similar changes in neural firing would take place in early visual areas of the human visual system, leading to changes in the perception of low-level visual features. In this study, we investigated whether contrast perception is affected by figure-ground assignment using stimuli similar to those in the electrophysiological studies in monkeys. We measured contrast discrimination thresholds and perceived contrast for Gabor probes placed on figures or the background and found that the perceived contrast of the probe was increased when it was placed on a figure. Furthermore, we tested how this effect compared with the well-known effect of orientation contrast on perceived contrast. We found that figure-ground assignment and orientation contrast produced changes in perceived contrast of a similar magnitude, and that they interacted. Our results demonstrate that figure-ground assignment influences perceived contrast, consistent with an effect of figure-ground assignment on activity in early visual areas of the human visual system. © 2015 ARVO.

  11. Exogenous contrast agents for thermoacoustic imaging: An investigation into the underlying sources of contrast

    Energy Technology Data Exchange (ETDEWEB)

    Ogunlade, Olumide, E-mail: o.ogunlade@ucl.ac.uk; Beard, Paul [Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT (United Kingdom)

    2015-01-15

    Purpose: Thermoacoustic imaging at microwave excitation frequencies is limited by the low differential contrast exhibited by high water content tissues. To overcome this, exogenous thermoacoustic contrast agents based on gadolinium compounds, iron oxide, and single wall carbon nanotubes have previously been suggested and investigated. However, these previous studies did not fully characterize the electric, magnetic, and thermodynamic properties of these agents thus precluding identification of the underlying sources of contrast. To address this, measurements of the complex permittivity, complex permeability, DC conductivity, and Grüneisen parameter have been made. These measurements allowed the origins of the contrast provided by each substance to be identified. Methods: The electric and magnetic properties of the contrast agents were characterized at 3 GHz using two rectangular waveguide cavities. The DC conductivity was measured separately using a conductivity meter. Thermoacoustic signals were then acquired and compared to those generated in water. Finally, 3D electromagnetic simulations were used to decouple the different contributions to the absorbed power density. Results: It was found that the gadolinium compounds provided appreciable electric contrast but not originating from the gadolinium itself. The contrast was either due to dissociation of the gadolinium salt which increased ionic conductivity or its nondissociated polar fraction which increased dielectric polarization loss or a combination of both. In addition, very high concentrations were required to achieve appreciable contrast, to the extent that the Grüneisen parameter increased significantly and became a source of contrast. Iron oxide particles were found to produce low but measurable dielectric contrast due to dielectric polarization loss, but this is attributed to the coating of the particles not the iron oxide. Single wall carbon nanotubes did not provide measurable contrast of any type

  12. Interval between injection of contrast material and positive contrast cheliography affects accurate diagnosis of diaphragmatic hernia

    Directory of Open Access Journals (Sweden)

    Ismail A. Sen

    2015-01-01

    Full Text Available The aim of this study was to evaluate the clinical, surgical and diagnostic imaging findings in 11 cats and 3 dogs with suspected acute and chronic traumatic diaphragmatic hernia, and to compare the results of positive contrast cheliography (peritoneography taken immediately and 5 min after the injection of contrast material. Thoracic and abdominal radiography, ultrasonography, and positive contrast cheliography of all animals were performed. Eight cases were considered as acute and six cases were considered chronic. The contrast images taken immediately after the injection of contrast material revealed the contrast material in the thoracic cavity in 8/8 acute trauma patients, but in none of the chronic cases. In 5/6 of these cases contrast material was seen in the thoracal cavity only in additional images taken after 5 min. One patient was diagnosed with FIP and excluded from the study. Twelve cases had complete resolution and one animal died during the early postoperative period. Our results suggest that positive contrast cheliography performed immediately after the injection of contrast material may not reveal chronic cases of diaphragmatic hernia and a second imaging (or imaging after 5 min is indicated in order not to overlook chronic cases.

  13. Contrast-enhanced angiographic cone-beam computed tomography without pre-diluted contrast medium

    Energy Technology Data Exchange (ETDEWEB)

    Jo, K.I.; Kim, S.R.; Choi, J.H.; Kim, K.H.; Jeon, P. [Sungkyunkwan University School of Medicine, Department of Radiology, Samsung Medical Center, Gangnam-gu, Seoul (Korea, Republic of)

    2015-11-15

    Contrast-enhanced cone-beam computed tomography (CBCT) has been introduced and accepted as a useful technique to evaluate delicate vascular anatomy and neurovascular stents. Current protocol for CBCT requires quantitative dilution of contrast medium to obtain adequate quality images. Here, we introduce simple methods to obtain contrast-enhanced CBCT without quantitative contrast dilution. A simple experiment was performed to estimate the change in flow rate in the internal carotid artery during the procedure. Transcranial doppler (TCD) was used to evaluate the velocity change before and after catheterization and fluid infusion. In addition, 0.3 cm{sup 3}/s (n = 3) and 0.2 cm{sup 3}/s (n = 7) contrast infusions were injected and followed by saline flushes using a 300 mmHg pressure bag to evaluate neurovascular stent and host arteries. Flow velocities changed -15 ± 6.8 % and +17 ± 5.5 % from baseline during catheterization and guiding catheter flushing with a 300 mmHg pressure bag, respectively. Evaluation of the stents and vascular structure was feasible using this technique in all patients. Quality assessment showed that the 0.2 cm{sup 3}/s contrast infusion protocol was better for evaluating the stent and host artery. Contrast-enhanced CBCT can be performed without quantitative contrast dilution. Adequate contrast dilution can be achieved with a small saline flush and normal blood flow. (orig.)

  14. Density contrast indicators in cosmological dust models

    Indian Academy of Sciences (India)

    contrast, which may or may not be monotonically increasing with time. We also find that monotonic- ity seems to be related to the initial conditions of the model, which may be of potential interest in connection with debates regarding gravitational entropy and the arrow of time. 1. Introduction. An important question in ...

  15. Refractive index contrast in porous silicon multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Nava, R.; Mora, M.B. de la; Tagueena-Martinez, J. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Rio, J.A. del [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Centro Morelense de Innovacion y Transferencia Tecnologica, Consejo de Ciencia y Tecnologia del Estado de Morelos (Mexico)

    2009-07-15

    Two of the most important properties of a porous silicon multilayer for photonic applications are flat interfaces and a relative large refractive index contrast between layers in the optical wavelength range. In this work, we studied the effect of the current density and HF electrolyte concentration on the refractive index of porous silicon. With the purpose of increasing the refractive index contrast in a multilayer, the refractive index of porous silicon produced at low current was studied in detail. The current density applied to produce the low porosity layers was limited in order to keep the electrolyte flow through the multilayer structure and to avoid deformation of layer interfaces. We found that an electrolyte composed of hydrofluoric acid, ethanol and glycerin in a ratio of 3:7:1 gives a refractive index contrast around 1.3/2.8 at 600 nm. Several multilayer structures with this refractive index contrast were fabricated, such as dielectric Bragg mirrors and microcavities. Reflectance spectra of the structures show the photonic quality of porous silicon multilayers produced under these electrochemical conditions. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Marginal contrasts and the Contrastivist Hypothesis

    Directory of Open Access Journals (Sweden)

    Daniel Currie Hall

    2016-12-01

    Full Text Available The Contrastivist Hypothesis (CH; Hall 2007; Dresher 2009 holds that the only features that can be phonologically active in any language are those that serve to distinguish phonemes, which presupposes that phonemic status is categorical. Many researchers, however, demonstrate the existence of gradient relations. For instance, Hall (2009 quantifies these using the information-theoretic measure of entropy (unpredictability of distribution and shows that a pair of sounds may have an entropy between 0 (totally predictable and 1 (totally unpredictable. We argue that the existence of such intermediate degrees of contrastiveness does not make the CH untenable, but rather offers insight into contrastive hierarchies. The existence of a continuum does not preclude categorical distinctions: a categorical line can be drawn between zero entropy (entirely predictable, and thus by the CH phonologically inactive and non-zero entropy (at least partially contrastive, and thus potentially phonologically active. But this does not mean that intermediate degrees of surface contrastiveness are entirely irrelevant to the CH; rather, we argue, they can shed light on how deeply ingrained a phonemic distinction is in the phonological system. As an example, we provide a case study from Pulaar [ATR] harmony, which has previously been claimed to be problematic for the CH.

  17. Embedded high-contrast distributed grating structures

    Science.gov (United States)

    Zubrzycki, Walter J.; Vawter, Gregory A.; Allerman, Andrew A.

    2002-01-01

    A new class of fabrication methods for embedded distributed grating structures is claimed, together with optical devices which include such structures. These new methods are the only known approach to making defect-free high-dielectric contrast grating structures, which are smaller and more efficient than are conventional grating structures.

  18. Nature versus Nurture: The Simple Contrast

    Science.gov (United States)

    Davidoff, Jules; Goldstein, Julie; Roberson, Debi

    2009-01-01

    We respond to the commentary of Franklin, Wright, and Davies ("Journal of Experimental Child Psychology, 102", 239-245 [2009]) by returning to the simple contrast between nature and nurture. We find no evidence from the toddler data that makes us revise our ideas that color categories are learned and never innate. (Contains 1 figure.)

  19. Using the phase-space imager to analyze partially coherent imaging systems: bright-field, phase contrast, differential interference contrast, differential phase contrast, and spiral phase contrast

    Science.gov (United States)

    Mehta, Shalin B.; Sheppard, Colin J. R.

    2010-05-01

    Various methods that use large illumination aperture (i.e. partially coherent illumination) have been developed for making transparent (i.e. phase) specimens visible. These methods were developed to provide qualitative contrast rather than quantitative measurement-coherent illumination has been relied upon for quantitative phase analysis. Partially coherent illumination has some important advantages over coherent illumination and can be used for measurement of the specimen's phase distribution. However, quantitative analysis and image computation in partially coherent systems have not been explored fully due to the lack of a general, physically insightful and computationally efficient model of image formation. We have developed a phase-space model that satisfies these requirements. In this paper, we employ this model (called the phase-space imager) to elucidate five different partially coherent systems mentioned in the title. We compute images of an optical fiber under these systems and verify some of them with experimental images. These results and simulated images of a general phase profile are used to compare the contrast and the resolution of the imaging systems. We show that, for quantitative phase imaging of a thin specimen with matched illumination, differential phase contrast offers linear transfer of specimen information to the image. We also show that the edge enhancement properties of spiral phase contrast are compromised significantly as the coherence of illumination is reduced. The results demonstrate that the phase-space imager model provides a useful framework for analysis, calibration, and design of partially coherent imaging methods.

  20. Lexical representation of novel L2 contrasts

    Science.gov (United States)

    Hayes-Harb, Rachel; Masuda, Kyoko

    2005-04-01

    There is much interest among psychologists and linguists in the influence of the native language sound system on the acquisition of second languages (Best, 1995; Flege, 1995). Most studies of second language (L2) speech focus on how learners perceive and produce L2 sounds, but we know of only two that have considered how novel sound contrasts are encoded in learners' lexical representations of L2 words (Pallier et al., 2001; Ota et al., 2002). In this study we investigated how native speakers of English encode Japanese consonant quantity contrasts in their developing Japanese lexicons at different stages of acquisition (Japanese contrasts singleton versus geminate consonants but English does not). Monolingual English speakers, native English speakers learning Japanese for one year, and native speakers of Japanese were taught a set of Japanese nonwords containing singleton and geminate consonants. Subjects then performed memory tasks eliciting perception and production data to determine whether they encoded the Japanese consonant quantity contrast lexically. Overall accuracy in these tasks was a function of Japanese language experience, and acoustic analysis of the production data revealed non-native-like patterns of differentiation of singleton and geminate consonants among the L2 learners of Japanese. Implications for theories of L2 speech are discussed.

  1. Bounding the bias of contrastive divergence learning

    DEFF Research Database (Denmark)

    Fischer, Anja; Igel, Christian

    2011-01-01

    Optimization based on k-step contrastive divergence (CD) has become a common way to train restricted Boltzmann machines (RBMs). The k-step CD is a biased estimator of the log-likelihood gradient relying on Gibbs sampling. We derive a new upper bound for this bias. Its magnitude depends on k...

  2. Phase-contrast X-ray CT

    Energy Technology Data Exchange (ETDEWEB)

    Momose, Atsushi [Hitachi Ltd., Saitama (Japan). Advanced Research Laboratory; Takeda, Tohoru; Itai, Yuji

    1995-12-01

    Phase-contrast X-ray computed tomography (CT) enabling the observation of biological soft tissues without contrast enhancement has been developed. The X-ray phase shift caused by an object is measured and input to a standard CT reconstruction algorithm. A thousand times increase in the image sensitivity to soft tissues is achieved compared with the conventional CT using absorption contrast. This is because the X-ray phase shift cross section of light elements is about a thousand times larger than the absorption cross section. The phase shift is detected using an X-ray interferometer and computer analyses of interference patterns. Experiments were performed using a synchrotron X-ray source. Excellent image sensitivity is demonstrated in the observation of cancerous rabbit liver. The CT images distinguish cancer lesion from normal liver tissue and, moreover, visualize the pathological condition in the lesion. Although the X-ray energy employed and the present observation area size are not suitable for medical applications as they are, phase-contrast X-ray CT is promising for investigating the internal structure of soft tissue which is almost transparent for X-rays. The high sensitivity also provides the advantage of reducing X-ray doses. (author).

  3. Progress in high index contrast integrated optics

    NARCIS (Netherlands)

    Baets, R.G.F.; Bienstman, P.; Bogaerts, W.; Brouckaert, J.; De Backere, P.; Dumon, P.; Roelkens, G.; Scheerlinck, S.; Smit, M.K.; Taillaert, D.; Van Campenhout, J.; Van Laere, F.; Thourhout, Van D.

    2007-01-01

    A large fraction of the recent innovation in integrated optics is enabled by the use of high index contrast structures and devices. The strong confinement achievable in such devices allows for dramatic performance benefits and downscaling. In this paper the progress in this field is reviewed.

  4. Radiculography with water-soluble contraste medium

    International Nuclear Information System (INIS)

    Araujo Pinheiro, R.S. de

    1987-01-01

    The etiologic diagnosis of the lumbar pain is discussed. The radiculography with water-soluble contrast medium is used and 250 cases are studied. Some practical criteria of indication executation and interpretation of the examination are reported. (M.A.C.) [pt

  5. Two Contrasting Concepts of Participatory Leadership.

    Science.gov (United States)

    Harman, Willis W.

    1981-01-01

    Two contrasting concepts of how humans can best manage affairs and express leadership are explored. Both concepts concur in the conviction that bureaucratic/hierarchical management forms are due to be replaced by a better form. The concepts differ in underlying assumptions about the nature of the human mind and of leadership. (CJ)

  6. Cardiac image segmentation for contrast agent videodensitometry

    NARCIS (Netherlands)

    Mischi, M.; Kalker, A.A.C.M.; Korsten, H.H.M.

    2005-01-01

    Indicator dilution techniques are widely used in the intensive care unit and operating room for cardiac parameter measurements. However, the invasiveness of current techniques represents a limitation for their clinical use. The development of stable ultrasound contrast agents allows new applications

  7. International guidelines for contrast-enhanced ultrasonography

    DEFF Research Database (Denmark)

    Nolsøe, Christian Pállson; Lorentzen, Torben

    2016-01-01

    The intent of this review is to discuss and comment on common clinical scenarios in which contrast-enhanced ultrasonography (CEUS) may play a decisive role and to illustrate important points with typical cases. With the advent of CEUS, the scope of indications for ultrasonography has been dramati...

  8. Recent hot topics in contrast media

    DEFF Research Database (Denmark)

    Thomsen, Henrik S

    2011-01-01

    This editorial reviews the way in which the facts related to the safety of iodinated and gadolinium based contrast agents have emerged over the last two decades. This is especially important given their ever increasing usage in modern computed tomographic (CT) and Magnetic resonance imaging (MRI)...

  9. CONTRASTIVE CULTURAL FEATURES IN FL TEACHING.

    Science.gov (United States)

    FISCHER, MILLA

    CONTRASTIVE CULTURAL FEATURES SHOULD BE INCLUDED WITHIN THE FRAMEWORK OF THE GRAMMATICAL LESSON AS A MEANS OF COUNTERBALANCING THE GENERALLY UNSATISFACTORY MATERIAL USED FOR RUSSIAN TEXTS. LESSONS FOR AMERICAN STUDENTS LEARNING RUSSIAN SHOULD INCLUDE PHONOLOGICAL DRILLS ON VOWEL LENGTHS, DISTRIBUTION OF VOICED OBSTRUENTS, AND OBSTRUENT CLUSTERS,…

  10. Contrast agents in magnetic resonance imaging

    International Nuclear Information System (INIS)

    Karadjian, V.

    1987-01-01

    The origine of nuclear magnetic resonance signal is reminded and different ways for contrast enhancement in magnetic resonance imaging are presented, especially, modifications of tissus relaxation times. Investigations have focused on development of agents incorporating either paramagnetic ions or stable free radicals. Pharmacological and toxicological aspects are developed. The diagnostic potential of these substances is illustrated by the example of gadolinium complexes [fr

  11. Contrast-enhanced MRI of the lung

    International Nuclear Information System (INIS)

    Kauczor, Hans-Ulrich; Kreitner, Karl-Friedrich

    2000-01-01

    The lung has long been neglected by MR imaging. This is due to unique intrinsic difficulties: (1) signal loss due to cardiac pulsation and respiration; (2) susceptibility artifacts caused by multiple air-tissue interfaces; (3) low proton density. There are many MR strategies to overcome these problems. They consist of breath-hold imaging, respiratory and cardiac gating procedures, use of short repetition and echo times, increase of the relaxivity of existing spins by administration of intravenous contrast agents, and enrichment of spin density by hyperpolarized noble gases or oxygen. Improvements in scanner performance and frequent use of contrast media have increased the interest in MR imaging and MR angiography of the lung. They can be used on a routine basis for the following indications: characterization of pulmonary nodules, staging of bronchogenic carcinoma, in particular assessment of chest wall invasion; evaluation of inflammatory activity in interstitial lung disease; acute pulmonary embolism, chronic thromboembolic pulmonary hypertension, vascular involvement in malignant disease; vascular abnormalities. Future perspectives include perfusion imaging using extracellular or intravascular (blood pool) contrast agents and ventilation imaging using inhalation of hyperpolarized noble gases, of paramagnetic oxygen or of aerosolized contrast agents. These techniques represent new approaches to functional lung imaging. The combination of visualization of morphology and functional assessment of ventilation and perfusion is unequalled by any other technique

  12. Contrast media safety-an update

    DEFF Research Database (Denmark)

    Thomsen, Henrik S

    2011-01-01

    The value of contrast agents has for long been documented by their common daily use in imaging departments worldwide. In principle, they should be injected and leave the body immediately after use in the same condition or undergo natural metabolism without making any harm to the patient. However...

  13. Internal noise sources limiting contrast sensitivity.

    Science.gov (United States)

    Silvestre, Daphné; Arleo, Angelo; Allard, Rémy

    2018-02-07

    Contrast sensitivity varies substantially as a function of spatial frequency and luminance intensity. The variation as a function of luminance intensity is well known and characterized by three laws that can be attributed to the impact of three internal noise sources: early spontaneous neural activity limiting contrast sensitivity at low luminance intensities (i.e. early noise responsible for the linear law), probabilistic photon absorption at intermediate luminance intensities (i.e. photon noise responsible for de Vries-Rose law) and late spontaneous neural activity at high luminance intensities (i.e. late noise responsible for Weber's law). The aim of this study was to characterize how the impact of these three internal noise sources vary with spatial frequency and determine which one is limiting contrast sensitivity as a function of luminance intensity and spatial frequency. To estimate the impact of the different internal noise sources, the current study used an external noise paradigm to factorize contrast sensitivity into equivalent input noise and calculation efficiency over a wide range of luminance intensities and spatial frequencies. The impact of early and late noise was found to drop linearly with spatial frequency, whereas the impact of photon noise rose with spatial frequency due to ocular factors.

  14. Theory and Contrastive Explanation in Ethnography

    Science.gov (United States)

    Lichterman, Paul; Reed, Isaac Ariail

    2015-01-01

    We propose three interlinked ways that theory helps researchers build causal claims from ethnographic research. First, theory guides the casing and re-casing of a topic of study. Second, theoretical work helps craft a clear causal question via the construction of a contrast space of the topic of investigation. Third, the researcher uses theory to…

  15. Recent hot topics in contrast media

    DEFF Research Database (Denmark)

    Thomsen, Henrik S

    2011-01-01

    This editorial reviews the way in which the facts related to the safety of iodinated and gadolinium based contrast agents have emerged over the last two decades. This is especially important given their ever increasing usage in modern computed tomographic (CT) and Magnetic resonance imaging (MRI...

  16. Subwavelength Hyperlens Resolution With Perfect Contrast Function

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Repän, Taavi; Zhukovsky, Sergei

    2018-01-01

    , in principle, two sources standing apart at any subwavelength distance can be distinguished. We suggest two feasible designs, the first of which employs the obliquely incident light, while the second one is based on a properly designed metasurface. The concept can be used in high‐contrast subwavelength...

  17. Contrast effects on stop consonant identification.

    Science.gov (United States)

    Diehl, R L; Elman, J L; McCusker, S B

    1978-11-01

    Changes in the identification of speech sounds following selective adaptation are usually attributed to a reduction in sensitivity of auditory feature detectors. An alternative explanation of these effects is based on the notion of response contrast. In several experiments, subjects identified the initial segment of synthetic consonant-vowel syllables as either the voiced stop [b] or the voiceless stop [ph]. Each test syllable had a value of voice onset time (VOT) that placed it near the English voiced-voiceless boundary. When the test syllables were preceded by a single clear [b] (VOT = -100 msec), subjects tended to identify them as [ph], whereas when they were preceded by an unambiguous [ph] (VOT = 100 msec), the syllables were predominantly labeled [b]. This contrast effect occurred even when the contextual stimuli were velar and the test stimuli were bilabial, which suggests a featural rather than a phonemic basis for the effect. To discount the possibility that these might be instances of single-trial sensory adaptation, we conducted a similar experiment in which the contextual stimuli followed the test items. Reliable contrast effects were still obtained. In view of these results, it appears likely that response contrast accounts for at least some component of the adaptation effects reported in the literature.

  18. Representations in Calculus: Two Contrasting Cases.

    Science.gov (United States)

    Aspinwall, Leslie; Shaw, Kenneth L.

    2002-01-01

    Illustrates the contrasting thinking processes of two beginning calculus students' geometric and analytic schemes for the derivative function. Suggests that teachers can enhance students' understanding by continuing to demonstrate how different representations of the same mathematical concept provide additional information. (KHR)

  19. Contrast media osmolality and plasma volume changes

    International Nuclear Information System (INIS)

    Hine, A.L.; Lui, D.; Dawson, P.; Middlesex Hospital, London

    1985-01-01

    A theoretical and experimental study of the plasma volume expansion consequent on the hyperosmolality of contrast media is presented. In the case of the ratio 1.5 media theory and experiment coincide closely but in the case of the ratio 3 media the observed changes exceed the predicted. It is proposed that this is due partly to the slower diffusion of the ratio 3 media out of the intravascular space and partly due to the fact that the osmotic load presented by these media is greater than would be expected from a study of their commercial solutions in which osmolality is reduced by molecular aggregation. The implications for the relative haemodynamic effects of different contrast media are discussed. The osmotic effects of contrast media also play a part in determining the image quality achievable in intravenous digital subtraction angiography (IV-DSA). It is predicted that ratio 3 contrast media will give better quality images in IV-DSA than ratio 1.5 media. (orig.)

  20. Semantics, contrastive linguistics and parallel corpora

    Directory of Open Access Journals (Sweden)

    Violetta Koseska

    2014-09-01

    Full Text Available Semantics, contrastive linguistics and parallel corpora In view of the ambiguity of the term “semantics”, the author shows the differences between the traditional lexical semantics and the contemporary semantics in the light of various semantic schools. She examines semantics differently in connection with contrastive studies where the description must necessary go from the meaning towards the linguistic form, whereas in traditional contrastive studies the description proceeded from the form towards the meaning. This requirement regarding theoretical contrastive studies necessitates construction of a semantic interlanguage, rather than only singling out universal semantic categories expressed with various language means. Such studies can be strongly supported by parallel corpora. However, in order to make them useful for linguists in manual and computer translations, as well as in the development of dictionaries, including online ones, we need not only formal, often automatic, annotation of texts, but also semantic annotation - which is unfortunately manual. In the article we focus on semantic annotation concerning time, aspect and quantification of names and predicates in the whole semantic structure of the sentence on the example of the “Polish-Bulgarian-Russian parallel corpus”.

  1. Contrast enhancement of mail piece images

    Science.gov (United States)

    Shin, Yong-Chul; Sridhar, Ramalingam; Demjanenko, Victor; Palumbo, Paul W.; Hull, Jonathan J.

    1992-08-01

    A New approach to contrast enhancement of mail piece images is presented. The contrast enhancement is used as a preprocessing step in the real-time address block location (RT-ABL) system. The RT-ABL system processes a stream of mail piece images and locates destination address blocks. Most of the mail pieces (classified into letters) show high contrast between background and foreground. As an extreme case, however, the seasonal greeting cards usually use colored envelopes which results in reduced contrast osured by an error rate by using a linear distributed associative memory (DAM). The DAM is trained to recognize the spectra of three classes of images: with high, medium, and low OCR error rates. The DAM is not forced to make a classification every time. It is allowed to reject as unknown a spectrum presented that does not closely resemble any that has been stored in the DAM. The DAM was fairly accurate with noisy images but conservative (i.e., rejected several text images as unknowns) when there was little ground and foreground degradations without affecting the nondegraded images. This approach provides local enhancement which adapts to local features. In order to simplify the computation of A and (sigma) , dynamic programming technique is used. Implementation details, performance, and the results on test images are presented in this paper.

  2. Two new contrast media in coronary angiography

    International Nuclear Information System (INIS)

    Selin, K.; Bjoerk, L.

    1983-01-01

    Amipaque, ioxaglic acid and Isopaque Coronar 300 were compared in a double blind investigation of coronary angiography in patients with ischemic heart disease. Amipaque affected systolic blood pressure and ECG less than the other contrast media. Ioxaglic acid appeared to give more ST and T changes than Isopaque Coronar. (Auth.)

  3. Generalised phase contrast: microscopy, manipulation and more

    DEFF Research Database (Denmark)

    Palima, Darwin; Glückstad, Jesper

    2010-01-01

    Generalised phase contrast (GPC) not only leads to more accurate phase imaging beyond thin biological samples, but serves as an enabling framework in developing tools over a wide spectrum of contemporary applications in optics and photonics, including optical trapping and micromanipulation, optic...

  4. Advanced detection strategies for ultrasound contrast agents

    NARCIS (Netherlands)

    J.M.G. Borsboom (Jerome)

    2005-01-01

    markdownabstract__Abstract__ Ultrasound contrast agent was discovered serendipitously by Gramiak and Shah in I968 when they injected indocyanine green dye into the heart and observed increased echogenicity of the blood containing the dye. Small cavitation bubbles that were formed upon

  5. Nonspherical oscilllations of ultrasound contrast agent microbubbles

    NARCIS (Netherlands)

    Dollet, B.; van der Meer, S.M.; Garbin, V.; Garbin, Valeria; de Jong, N.; Lohse, Detlef; Versluis, Michel

    2008-01-01

    The occurrence of nonspherical oscillations (or surface modes) of coated microbubbles, used as ultrasound contrast agents in medical imaging, is investigated using ultra–high-speed optical imaging. Optical tweezers designed to micromanipulate single bubbles in 3-D are used to trap the bubbles far

  6. Homogenization of High-Contrast Brinkman Flows

    KAUST Repository

    Brown, Donald L.

    2015-04-16

    Modeling porous flow in complex media is a challenging problem. Not only is the problem inherently multiscale but, due to high contrast in permeability values, flow velocities may differ greatly throughout the medium. To avoid complicated interface conditions, the Brinkman model is often used for such flows [O. Iliev, R. Lazarov, and J. Willems, Multiscale Model. Simul., 9 (2011), pp. 1350--1372]. Instead of permeability variations and contrast being contained in the geometric media structure, this information is contained in a highly varying and high-contrast coefficient. In this work, we present two main contributions. First, we develop a novel homogenization procedure for the high-contrast Brinkman equations by constructing correctors and carefully estimating the residuals. Understanding the relationship between scales and contrast values is critical to obtaining useful estimates. Therefore, standard convergence-based homogenization techniques [G. A. Chechkin, A. L. Piatniski, and A. S. Shamev, Homogenization: Methods and Applications, Transl. Math. Monogr. 234, American Mathematical Society, Providence, RI, 2007, G. Allaire, SIAM J. Math. Anal., 23 (1992), pp. 1482--1518], although a powerful tool, are not applicable here. Our second point is that the Brinkman equations, in certain scaling regimes, are invariant under homogenization. Unlike in the case of Stokes-to-Darcy homogenization [D. Brown, P. Popov, and Y. Efendiev, GEM Int. J. Geomath., 2 (2011), pp. 281--305, E. Marusic-Paloka and A. Mikelic, Boll. Un. Mat. Ital. A (7), 10 (1996), pp. 661--671], the results presented here under certain velocity regimes yield a Brinkman-to-Brinkman upscaling that allows using a single software platform to compute on both microscales and macroscales. In this paper, we discuss the homogenized Brinkman equations. We derive auxiliary cell problems to build correctors and calculate effective coefficients for certain velocity regimes. Due to the boundary effects, we construct

  7. Epinephrine inhanced double contrast knee arthrography

    International Nuclear Information System (INIS)

    Lee, Jae Mun; Choi, Byung Ihn

    1981-01-01

    It is well known that double contrast knee arthrography is useful in diagnosis of meniscal lesions and other knee pathology. But intra-articular structures become less well delineated shortly after injection into the knee joint with water soluble contrast media because of rapid absorption and dilution of the injected media. This limits the time when sharply detailed arthrograms are obtainable and precludes repeat delayed arthrogram without reinjection of contrast media. In order to overcome this major disadvantage, the authors used epinephrine which has vasoconstrictive effect and is expected to reduce fluid movement across the synovial membrane temporarily. The authors attempted to compare epinephrine inhanced double contrast arthrographic group, epinephrine(+) group, to the double contrast arthrographic group without epinephrine, epinephrine(-) group, by statistical evaluation. Each group consisted of 35 cases and 7 lateral films of knee joint were taken sequentially 2, 6, 10, 15, 20, 30, and 60 minutes after injection of contrast media, and were assessed by 5 certified radiologists. The results were as follows: 1. The difference of mean score of quality between epinephrine(+) group and epinephrine(-) group was statistically significant at every time interval (ρ value < 0.01 at 2 minutes, ρ < 0.001 at all other time intervals). Epinephrine(+) group was superior to the epinephrine(-) group in quality of film. 2. Numbers of cases above score of 2 which was considered to be of diagnostic quality in evaluating meniscal lesions were larger in epinephrine(+) group than epinephrine(-) group at every time interval. And the difference between two groups was highly significant statistically (ρ < 0.001). 3. Only 43% of cases was above score of 2 at 10 minutes in epinephrine(-) group, but 97% at 10 minutes and 80% at 20 minutes respectively in epinephrine(+) group. Therefore duration for adequate study of arthrogram is prolonged more than two times in epinephrine(+) group

  8. In-vitro effects of tri-iodinated X-ray contrast media on blood coagulation, fibrinolysis and complement system

    International Nuclear Information System (INIS)

    Blanke, D.

    1982-01-01

    In-vitro experiments with Jodipamid, Jothalamat and Diatrizoat served the purpose of determining influences of contrast media on blood coagulation, fibrinolysis and the complement system. For all three contrast media investigated the effect noted was dose-dependent and was only brought about by concentrations higher than physiological ones. Liver-pathway Jodipamid was seen to have a much stronger effect than the two renal-pathway contrast media Jothalamat and Diatrizoat, which is probably due to the different protein binding capacities. In detail, the results with Jodipamid were as follows: a sharp fall in thrombinogen, a distinct decrease in fibrinogen both in the immunological and functional test, but only delayed decrease in complement factor C 4. Fibrinolytic fission products were found after applying the dose of 30 mM, as compared to 400 mM for the renal-pathway contrast media. Furthermore the functional tests (F I and F II) with Jothalamat and Diatrizoat showed only slight effects, the immunological ones (F I and C 4) none at all. The influence of the contrast media on factors I and II is interpreted by the author as an inhibition of fibrin polymerization. What seems to be the verification of fibrinolytic fission products is explained by a non-specific agglutination reaction, the decrease in C 4 by contrast-medium-induced protein denaturation. (orig./MG) [de

  9. Comparison of neutral oral contrast versus positive oral contrast medium in abdominal multidetector CT

    International Nuclear Information System (INIS)

    Berther, Ralph; Eckhardt, Boris; Zollikofer, Christoph L.; Patak, Michael A.; Erturk, Sukru M.

    2008-01-01

    To determine whether neutral contrast agents with water-equivalent intraluminal attenuation can improve delineation of the bowel wall and increase overall image quality for a non-selected patient population, a neutral oral contrast agent (3% mannitol) was administered to 100 patients referred for abdominal multidetector row computed tomography (MDCT). Their results were compared with those of 100 patients given a positive oral contrast agent. Qualitative and quantitative measurements were done on different levels of the gastrointestinal tract by three experienced readers. Patients given the neutral oral contrast agent showed significant better qualitative results for bowel distension (P<0.001), homogeneity of the luminal content (P<0.001), delineation of the bowel-wall to the lumen (P<0.001) and to the mesentery (P<0.001) and artifacts (P<0.001), leading to a significant better overall image quality (P<0.001) than patients receiving positive oral contrast medium. The quantitative measurements revealed significant better distension (P<0.001) and wall to lumen delineation (P<0.001) for the patients receiving neutral oral contrast medium. The present results show that the neutral oral contrast agent (mannitol) produced better distension, better homogeneity and better delineation of the bowel wall leading to a higher overall image quality than the positive oral contrast medium in a non-selected patient population. (orig.)

  10. Dynamic Contrast-Enhanced Magnetic Resonance Enterography and Dynamic Contrast-Enhanced Ultrasonography in Crohn's Disease

    DEFF Research Database (Denmark)

    Wilkens, Rune; Peters, David A; Nielsen, Agnete Hedemann

    2017-01-01

    Purpose e Cross-sectional imaging methods are important for objective evaluationof small intestinal inflammationinCrohn'sdisease(CD).The primary aim was to compare relative parameters of intestinal perfusion between contrast-enhanced ultrasonography (CEUS) and dynamic contrast-enhanced magnetic...

  11. Contrast enhancement by lipid-based MRI contrast agents in mouse atherosclerotic plaques; a longitudinal study

    NARCIS (Netherlands)

    den Adel, Brigit; van der Graaf, Linda M.; Que, Ivo; Strijkers, Gustav J.; Löwik, Clemens W.; Poelmann, Robert E.; van der Weerd, Louise

    2013-01-01

    The use of contrast-enhanced MRI to enable in vivo specific characterization of atherosclerotic plaques is increasing. In this study the intrinsic ability of two differently sized gadolinium-based contrast agents to enhance atherosclerotic plaques in ApoE(-/-) mice was evaluated with MRI. We

  12. Iodinated contrast media and contrast-induced nephropathy: is there a preferred cost-effective agent?

    Science.gov (United States)

    Sharma, Samin K

    2008-05-01

    Over 20 years have passed since the introduction of the tri-iodinated low-osmolar nonionic contrast agents such as iopamidol, iohexol, ioversol and iopromide. During this time, most cardiology practices have switched to these nonionic agents to avoid the nuisance side effects and cardiac adverse events associated with the older ionic contrast agents. Although the improved tolerability of the nonionic agents is generally attributed to their decreased osmolality (approximately half that of the older ionic contrast agents), in fact, these contrast agents also differ from the older agents in their ionicity, viscosity and direct chemotoxicity. The impact of these properties on safety, together with cost differences, should be considered when selecting a contrast agent.

  13. Equilibrium-phase MR angiography: Comparison of unspecific extracellular and protein-binding gadolinium-based contrast media with respect to image quality.

    Science.gov (United States)

    Erb-Eigner, Katharina; Taupitz, Matthias; Asbach, Patrick

    2016-01-01

    The purpose of this study was to compare contrast and image quality of whole-body equilibrium-phase high-spatial-resolution MR angiography using a non-protein-binding unspecific extracellular gadolinium-based contrast medium with that of two contrast media with different protein-binding properties. 45 patients were examined using either 15 mL of gadobutrol (non-protein-binding, n = 15), 32 mL of gadobenate dimeglumine (weakly protein binding, n = 15) or 11 mL gadofosveset trisodium (protein binding, n = 15) followed by equilibrium-phase high-spatial-resolution MR-angiography of four consecutive anatomic regions. The time elapsed between the contrast injection and the beginning of the equilibrium-phase image acquisition in the respective region was measured and was up to 21 min. Signal intensity was measured in two vessels per region and in muscle tissue. Relative contrast (RC) values were calculated. Vessel contrast, artifacts and image quality were rated by two radiologists in consensus on a five-point scale. Compared with gadobutrol, gadofosveset trisodium revealed significantly higher RC values only when acquired later than 15 min after bolus injection. Otherwise, no significant differences between the three contrast media were found regarding vascular contrast and image quality. Equilibrium-phase high-spatial-resolution MR-angiography using a weakly protein-binding or even non-protein-binding contrast medium is equivalent to using a stronger protein-binding contrast medium when image acquisition is within the first 15 min after contrast injection, and allows depiction of the vasculature with high contrast and image quality. The protein-binding contrast medium was superior for imaging only later than 15 min after contrast medium injection. Copyright © 2015 John Wiley & Sons, Ltd.

  14. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

    International Nuclear Information System (INIS)

    Müller, Mark; Yaroshenko, Andre; Velroyen, Astrid; Tapfer, Arne; Bech, Martin; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

    2015-01-01

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed

  15. Effects of First-Grade Number Knowledge Tutoring With Contrasting Forms of Practice.

    Science.gov (United States)

    Fuchs, Lynn S; Geary, David C; Compton, Donald L; Fuchs, Douglas; Schatschneider, Christopher; Hamlett, Carol L; Deselms, Jacqueline; Seethaler, Pamela M; Wilson, Julie; Craddock, Caitlin F; Bryant, Joan D; Luther, Kurstin; Changas, Paul

    2013-01-01

    The purpose of this study was to investigate the effects of 1st-grade number knowledge tutoring with contrasting forms of practice. Tutoring occurred 3 times per week for 16 weeks. In each 30-min session, the major emphasis (25 min) was number knowledge; the other 5 min provided practice in 1 of 2 forms. Nonspeeded practice reinforced relations and principles addressed in number knowledge tutoring. Speeded practice promoted quick responding and use of efficient counting procedures to generate many correct responses. At-risk students were randomly assigned to number knowledge tutoring with speeded practice ( n = 195), number knowledge tutoring with nonspeeded practice ( n = 190), and control (no tutoring, n = 206). Each tutoring condition produced stronger learning than control on all 4 mathematics outcomes. Speeded practice produced stronger learning than nonspeeded practice on arithmetic and 2-digit calculations, but effects were comparable on number knowledge and word problems. Effects of both practice conditions on arithmetic were partially mediated by increased reliance on retrieval, but only speeded practice helped at-risk children compensate for weak reasoning ability.

  16. Streaming flow from ultrasound contrast agents by acoustic waves in a blood vessel model.

    Science.gov (United States)

    Cho, Eunjin; Chung, Sang Kug; Rhee, Kyehan

    2015-09-01

    To elucidate the effects of streaming flow on ultrasound contrast agent (UCA)-assisted drug delivery, streaming velocity fields from sonicated UCA microbubbles were measured using particle image velocimetry (PIV) in a blood vessel model. At the beginning of ultrasound sonication, the UCA bubbles formed clusters and translated in the direction of the ultrasound field. Bubble cluster formation and translation were faster with 2.25MHz sonication, a frequency close to the resonance frequency of the UCA. Translation of bubble clusters induced streaming jet flow that impinged on the vessel wall, forming symmetric vortices. The maximum streaming velocity was about 60mm/s at 2.25MHz and decreased to 15mm/s at 1.0MHz for the same acoustic pressure amplitude. The effect of the ultrasound frequency on wall shear stress was more noticeable. Maximum wall shear stress decreased from 0.84 to 0.1Pa as the ultrasound frequency decreased from 2.25 to 1.0MHz. The maximum spatial gradient of the wall shear stress also decreased from 1.0 to 0.1Pa/mm. This study showed that streaming flow was induced by bubble cluster formation and translation and was stronger upon sonication by an acoustic wave with a frequency near the UCA resonance frequency. Therefore, the secondary radiant force, which is much stronger at the resonance frequency, should play an important role in UCA-assisted drug delivery. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Reduced-Contrast Approximations for High-Contrast Multiscale Flow Problems

    KAUST Repository

    Chung, Eric T.; Efendiev, Yalchin

    2010-01-01

    In this paper, we study multiscale methods for high-contrast elliptic problems where the media properties change dramatically. The disparity in the media properties (also referred to as high contrast in the paper) introduces an additional scale that needs to be resolved in multiscale simulations. First, we present a construction that uses an integral equation to represent the highcontrast component of the solution. This representation involves solving an integral equation along the interface where the coefficients are discontinuous. The integral representation suggests some multiscale approaches that are discussed in the paper. One of these approaches entails the use of interface functions in addition to multiscale basis functions representing the heterogeneities without high contrast. In this paper, we propose an approximation for the solution of the integral equation using the interface problems in reduced-contrast media. Reduced-contrast media are obtained by lowering the variance of the coefficients. We also propose a similar approach for the solution of the elliptic equation without using an integral representation. This approach is simpler to use in the computations because it does not involve setting up integral equations. The main idea of this approach is to approximate the solution of the high-contrast problem by the solutions of the problems formulated in reduced-contrast media. In this approach, a rapidly converging sequence is proposed where only problems with lower contrast are solved. It was shown that this sequence possesses the convergence rate that is inversely proportional to the reduced contrast. This approximation allows choosing the reduced-contrast problem based on the coarse-mesh size as discussed in this paper. We present a simple application of this approach to homogenization of elliptic equations with high-contrast coefficients. The presented approaches are limited to the cases where there are sharp changes in the contrast (i.e., the high

  18. Climate and development: enhancing impact through stronger linkages in the implementation of the Paris Agreement and the Sustainable Development Goals (SDGs).

    Science.gov (United States)

    Gomez-Echeverri, Luis

    2018-05-13

    One of the greatest achievements in the global negotiations of 2015 that delivered the 2030 Agenda for Sustainable Development or Sustainable Development Goals (SDGs) and the Paris Agreement on climate change is that, for the first time, the linkages between climate and development were enshrined in each of the documents. This was done in recognition that climate change and development need to be addressed together in order not only to avoid harmful trade-offs and high costs, particularly for poorer countries, but also to exploit the benefits that come from strengthening these linkages. This review presents some of the latest data that argue for stronger linkages as well as the challenges of implementation which are not only politically and economically related but also include issues such as knowledge gaps, finance and governance. Finally, the review also presents a glimpse at the pathways that will be required to reach the ambitious global temperature targets of the Paris Agreement of less than 2°C above pre-industrial levels with efforts to limit temperature rise even further to 1.5°C. This provides the context for some conclusions and recommendations for policy-makers, including on methodologies for assessing linkages and leveraging them for greater benefit.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Authors.

  19. Climate and development: enhancing impact through stronger linkages in the implementation of the Paris Agreement and the Sustainable Development Goals (SDGs)

    Science.gov (United States)

    Gomez-Echeverri, Luis

    2018-05-01

    One of the greatest achievements in the global negotiations of 2015 that delivered the 2030 Agenda for Sustainable Development or Sustainable Development Goals (SDGs) and the Paris Agreement on climate change is that, for the first time, the linkages between climate and development were enshrined in each of the documents. This was done in recognition that climate change and development need to be addressed together in order not only to avoid harmful trade-offs and high costs, particularly for poorer countries, but also to exploit the benefits that come from strengthening these linkages. This review presents some of the latest data that argue for stronger linkages as well as the challenges of implementation which are not only politically and economically related but also include issues such as knowledge gaps, finance and governance. Finally, the review also presents a glimpse at the pathways that will be required to reach the ambitious global temperature targets of the Paris Agreement of less than 2°C above pre-industrial levels with efforts to limit temperature rise even further to 1.5°C. This provides the context for some conclusions and recommendations for policy-makers, including on methodologies for assessing linkages and leveraging them for greater benefit. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

  20. Malnutrition Increases With Obesity and Is a Stronger Independent Risk Factor for Postoperative Complications: A Propensity-Adjusted Analysis of Total Hip Arthroplasty Patients.

    Science.gov (United States)

    Fu, Michael C; D'Ambrosia, Christopher; McLawhorn, Alexander S; Schairer, William W; Padgett, Douglas E; Cross, Michael B

    2016-11-01

    Obesity is frequently associated with complications after total hip arthroplasty (THA) and is often concomitant with malnutrition. The purpose of this study was to investigate the independent morbidity risk of malnutrition relative to obesity. The National Surgical Quality Improvement Program from 2005 to 2013 was queried for elective primary THA cases. Malnutrition was defined as albumin malnutrition with 30-day outcomes. A total of 40,653 THA cases were identified, of which 20,210 (49.7%) had preoperative albumin measurements. Propensity score adjustment successfully reduced potential selection bias, with P > .05 for differences between those with and without albumin data. Malnutrition incidence increased from 2.8% in obese I to 5.7% in obese III patients. With multivariable propensity-adjusted logistic regression, malnutrition was a more robust predictor than any obesity class for any postoperative complication(s) (odds ratio [OR] 1.61, 95% confidence interval [CI] 1.25-2.08), major complications (OR 1.63, 95% CI 1.21-2.19), respiratory complications (OR 2.35, 95% CI 1.27-4.37), blood transfusions (OR 1.71, 95% CI 1.44-2.03), and extended length of stay (OR 1.35, 95% CI 1.14-1.59). Malnutrition incidence increased significantly from obese I to obese III patients and was a stronger and more consistent predictor than obesity of complications after THA. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Thermodynamic studies of a series of homologous HIV-1 TAR RNA ligands reveal that loose binders are stronger Tat competitors than tight ones.

    Science.gov (United States)

    Pascale, Lise; Azoulay, Stéphane; Di Giorgio, Audrey; Zenacker, Laura; Gaysinski, Marc; Clayette, Pascal; Patino, Nadia

    2013-06-01

    RNA is a major drug target, but the design of small molecules that modulate RNA function remains a great challenge. In this context, a series of structurally homologous 'polyamide amino acids' (PAA) was studied as HIV-1 trans-activating response (TAR) RNA ligands. An extensive thermodynamic study revealed the occurence of an enthalpy-entropy compensation phenomenon resulting in very close TAR affinities for all PAA. However, their binding modes and their ability to compete with the Tat fragment strongly differ according to their structure. Surprisingly, PAA that form loose complexes with TAR were shown to be stronger Tat competitors than those forming tight ones, and thermal denaturation studies demonstrated that loose complexes are more stable than tight ones. This could be correlated to the fact that loose and tight ligands induce distinct RNA conformational changes as revealed by circular dichroism experiments, although nuclear magnetic resonance (NMR) experiments showed that the TAR binding site is the same in all cases. Finally, some loose PAA also display promising inhibitory activities on HIV-infected cells. Altogether, these results lead to a better understanding of RNA interaction modes that could be very useful for devising new ligands of relevant RNA targets.

  2. 24-hour aortic blood pressure variability showed a stronger association with carotid damage than 24-hour brachial blood pressure variability: The SAFAR study.

    Science.gov (United States)

    Yu, Shikai; Chi, Chen; Protogerou, Athanase D; Safar, Michel E; Blacher, Jacques; Argyris, Antonis A; Nasothimiou, Efthimia G; Sfikakis, Petros P; Papaioannou, Theodore G; Xu, Henry; Zhang, Yi; Xu, Yawei

    2018-03-01

    We aim to compare 24-hour aortic blood pressure variability (BPV) with brachial BPV in relation to carotid damage as estimated by carotid intima-media thickness (CIMT) and cross-sectional area (CCSA). Four hundred and forty five individuals received brachial and aortic 24-hour ambulatory BP monitoring with a validated device (Mobil-O-Graph). Systolic BPV was estimated by average real variability (ARV) and time-weighted standard deviation (wSD). In multiple logistic regression analysis, CIMT > 900 μm was significantly and independently associated with aortic ARV (OR = 1.38; 95% CI: 1.04-1.84), aortic wSD (OR = 1.65; 95% CI: 1.19-2.29) and brachial ARV (OR = 1.53; 95% CI: 1.07-2.18), but not with brachial wSD. CCSA > 90th percentile was significantly and independently associated with aortic ARV (OR = 1.50; 95% CI: 1.07-2.10) and wSD (OR = 1.70; 95% CI: 1.12-2.56), but not with brachial BPVs. In receiver operator characteristics curve analysis, aortic wSD identified CCSA > 90th percentile better than brachial wSD (AUC: 0.73 vs 0.68, P < .01). In conclusion, aortic 24-hour systolic BPV showed a slightly stronger association with carotid damage than brachial BPV. ©2018 Wiley Periodicals, Inc.

  3. The New Bail-in Regime and the Need for Stronger Market Discipline: What Can We Learn From the Greek Case?

    Directory of Open Access Journals (Sweden)

    Evangelos Vasileiou

    2014-01-01

    Full Text Available Effective Market Discipline (MD puzzles financial economists and regulators for decades, while the recent bail-in legislation for European banks extremely raises the need for even stronger MD. It may not be exaggeration to say that a new regime for the European banking market is born after the aforementioned decision. This paper’s objective is the broader MD examination, using variables that are not usually included in MD studies, but concern the European Union (EU and the European Monetary Union (EMU in the last years. In particular, apart from banking, deposit insurance and pure macroeconomic indicators, we also include governance and sovereign debt indices. The new regime may need a new MD approach. We choose Greece to implement our assumptions, because it is the country with the most severe economic, sovereign and governance problems in the EU. We employ data for the period 2002-10. The empirical evidence supports that market discipline is superficial, while there is ample evidence that MD is directly influenced by the poor governance performance and the excessive government debt. Greek authorities have to make major structural reforms in order to create the conditions for long-term stability, while our analysis points out some EMU’s shortfalls. 

  4. Fundamental studies of oral contrast agents for MR. Comparison of manganese agent and iron agent

    International Nuclear Information System (INIS)

    Fujita, Osamu; Hiraishi, Kumiko; Suginobu, Yoshito; Takeuchi, Masayasu; Narabayashi, Isamu

    1996-01-01

    We investigated and compared signal intensity and the effect of imaging the upper abdomen with blueberry juice (B.J.), a Mn agent utilizing the properties of paramagnetic metals, and FerriSeltz (F.S.), an iron agent. Since the relaxation effect was much stronger with B.J. than with F.S., the signal intensity required of a peroral contrast agent was able to be obtained at a much lower concentration of B.J. In imaging the upper abdomen, B.J. had a positive effect on imaging in T1-weighted images, and a negative effect in T2-weighted images. F.S. had a positive imaging effect in both, and because it showed extremely high signals in T2-weighted images, motion artifact arose. (author)

  5. Emotional cues, emotional signals, and their contrasting effects on listener valence

    DEFF Research Database (Denmark)

    Christensen, Justin

    2015-01-01

    that are mimetic of emotional cues interact in less clear and less cohesive manners with their corresponding haptic signals. For my investigations, subjects listen to samples from the International Affective Digital Sounds Library[2] and selected musical works on speakers in combination with a tactile transducer...... and of benefit to both the sender and the receiver of the signal, otherwise they would cease to have the intended effect of communication. In contrast with signals, animal cues are much more commonly unimodal as they are unintentional by the sender. In my research, I investigate whether subjects exhibit...... are more emotional cues (e.g. sadness or calmness). My hypothesis is that musical and sound stimuli that are mimetic of emotional signals should combine to elicit a stronger response when presented as a multimodal stimulus as opposed to as a unimodal stimulus, whereas musical or sound stimuli...

  6. Simulation-based comparison of two approaches frequently used for dynamic contrast-enhanced MRI

    International Nuclear Information System (INIS)

    Zwick, Stefan; Brix, Gunnar; Tofts, Paul S.; Strecker, Ralph; Kopp-Schneider, Annette; Laue, Hendrik; Semmler, Wolfhard; Kiessling, Fabian

    2010-01-01

    The purpose was to compare two approaches for the acquisition and analysis of dynamic-contrast-enhanced MRI data with respect to differences in the modelling of the arterial input-function (AIF), the dependency of the model parameters on physiological parameters and their numerical stability. Eight hundred tissue concentration curves were simulated for different combinations of perfusion, permeability, interstitial volume and plasma volume based on two measured AIFs and analysed according to the two commonly used approaches. The transfer constants (Approach 1) K trans and (Approach 2) k ep were correlated with all tissue parameters. K trans showed a stronger dependency on perfusion, and k ep on permeability. The volume parameters (Approach 1) v e and (Approach 2) A were mainly influenced by the interstitial and plasma volume. Both approaches allow only rough characterisation of tissue microcirculation and microvasculature. Approach 2 seems to be somewhat more robust than 1, mainly due to the different methods of CA administration. (orig.)

  7. Caldera resurgence driven by magma viscosity contrasts.

    Science.gov (United States)

    Galetto, Federico; Acocella, Valerio; Caricchi, Luca

    2017-11-24

    Calderas are impressive volcanic depressions commonly produced by major eruptions. Equally impressive is the uplift of the caldera floor that may follow, dubbed caldera resurgence, resulting from magma accumulation and accompanied by minor eruptions. Why magma accumulates, driving resurgence instead of feeding large eruptions, is one of the least understood processes in volcanology. Here we use thermal and experimental models to define the conditions promoting resurgence. Thermal modelling suggests that a magma reservoir develops a growing transition zone with relatively low viscosity contrast with respect to any newly injected magma. Experiments show that this viscosity contrast provides a rheological barrier, impeding the propagation through dikes of the new injected magma, which stagnates and promotes resurgence. In explaining resurgence and its related features, we provide the theoretical background to account for the transition from magma eruption to accumulation, which is essential not only to develop resurgence, but also large magma reservoirs.

  8. Neurotoxicity of iodinated radiological contrast media

    International Nuclear Information System (INIS)

    Araujo Pinheiro, R.S. de

    1988-01-01

    We studied during the last ten years the neurotoxicity of artificial iodinated contrast media, with prospective clinical and experimental protocols. The experimental investigation in animals aimed to understand the relationship between the intracarotid injection, the subarachnoid application and the integrity of the blood-brain barrier function. The electro physiologic disturbances and the morphologic observation of pial circulation support the evidence that iodinated artificial contrast media induces significant alterations in brain metabolism and in the autoregulation of the blood flow of the encephalon. Even if many of such phenomena may not be apparent at the clinical level, we supposed that they are always present and that their clinical exteriorization is prevented by the immediate and effective action of homeostatic mechanisms. (author)

  9. Contrast Gain Control Model Fits Masking Data

    Science.gov (United States)

    Watson, Andrew B.; Solomon, Joshua A.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    We studied the fit of a contrast gain control model to data of Foley (JOSA 1994), consisting of thresholds for a Gabor patch masked by gratings of various orientations, or by compounds of two orientations. Our general model includes models of Foley and Teo & Heeger (IEEE 1994). Our specific model used a bank of Gabor filters with octave bandwidths at 8 orientations. Excitatory and inhibitory nonlinearities were power functions with exponents of 2.4 and 2. Inhibitory pooling was broad in orientation, but narrow in spatial frequency and space. Minkowski pooling used an exponent of 4. All of the data for observer KMF were well fit by the model. We have developed a contrast gain control model that fits masking data. Unlike Foley's, our model accepts images as inputs. Unlike Teo & Heeger's, our model did not require multiple channels for different dynamic ranges.

  10. Dual-energy contrast-enhanced mammography.

    Science.gov (United States)

    Travieso Aja, M M; Rodríguez Rodríguez, M; Alayón Hernández, S; Vega Benítez, V; Luzardo, O P

    2014-01-01

    The degree of vascularization in breast lesions is related to their malignancy. For this reason, functional diagnostic imaging techniques have become important in recent years. Dual-energy contrast-enhanced mammography is a new, apparently promising technique in breast cancer that provides information about the degree of vascularization of the lesion in addition to the morphological information provided by conventional mammography. This article describes the state of the art for dual-energy contrast-enhanced mammography. Based on 15 months' clinical experience, we illustrate this review with clinical cases that allow us to discuss the advantages and limitations of this technique. Copyright © 2014 SERAM. Published by Elsevier Espana. All rights reserved.

  11. Contrast MR imaging of acute cerebral infarction

    Energy Technology Data Exchange (ETDEWEB)

    Kogame, Saeko; Syakudo, Miyuki; Inoue, Yuichi (Osaka City Univ. (Japan). Faculty of Medicine) (and others)

    1992-04-01

    Thirty patients with acute and subacute cerebral infarction (13 and 17 deep cerebral infarction) were studied with 0.5 T MR unit before and after intravenous injection of Gd-DTPA. Thirteen patients were studied within 7 days after neurological ictus, 17 patients were studied between 7 and 14 days. Two types of abnormal enhancement, cortical arterial and parenchymal enhancement, were noted. The former was seen in 3 of 4 cases of very acute cortical infarction within 4 days after clinical ictus. The latter was detected in all 7 cases of cortical infarction after the 6th day of the ictus, and one patient with deep cerebral infarction at the 12th day of the ictus. Gd-DTPA enhanced MR imaging seems to detect gyral enhancement earlier compared with contrast CT, and depict intra-arterial sluggish flow which was not expected to see on contrast CT scans. (author).

  12. Slovene-English Contrastive Phraseology: Lexical Collocations

    Directory of Open Access Journals (Sweden)

    Primož Jurko

    2010-05-01

    Full Text Available Phraseology is seen as one of the key elements and arguably the most productive part of any language. %e paper is focused on collocations and separates them from other phraseological units, such as idioms or compounds. Highlighting the difference between a monolingual and a bilingual (i.e. contrastive approach to collocation, the article presents two distinct classes of collocations: grammatical and lexical. %e latter, treated contrastively, represent the focal point of the paper, since they are an unending source of translation errors to both students of translation and professional translators. %e author introduces a methodology of systematic classification of lexical collocations applied on the Slovene-English language pair and based on structural (lexical congruence and semantic (translational predictability criteria.

  13. Enhanced renal image contrast by ethanol fixation in phase-contrast X-ray computed tomography.

    Science.gov (United States)

    Shirai, Ryota; Kunii, Takuya; Yoneyama, Akio; Ooizumi, Takahito; Maruyama, Hiroko; Lwin, Thet Thet; Hyodo, Kazuyuki; Takeda, Tohoru

    2014-07-01

    Phase-contrast X-ray imaging using a crystal X-ray interferometer can depict the fine structures of biological objects without the use of a contrast agent. To obtain higher image contrast, fixation techniques have been examined with 100% ethanol and the commonly used 10% formalin, since ethanol causes increased density differences against background due to its physical properties and greater dehydration of soft tissue. Histological comparison was also performed. A phase-contrast X-ray system was used, fitted with a two-crystal X-ray interferometer at 35 keV X-ray energy. Fine structures, including cortex, tubules in the medulla, and the vessels of ethanol-fixed kidney could be visualized more clearly than that of formalin-fixed tissues. In the optical microscopic images, shrinkage of soft tissue and decreased luminal space were observed in ethanol-fixed kidney; and this change was significantly shown in the cortex and outer stripe of the outer medulla. The ethanol fixation technique enhances image contrast by approximately 2.7-3.2 times in the cortex and the outer stripe of the outer medulla; the effect of shrinkage and the physical effect of ethanol cause an increment of approximately 78% and 22%, respectively. Thus, the ethanol-fixation technique enables the image contrast to be enhanced in phase-contrast X-ray imaging.

  14. Evaluation of contrast media for bronchography

    International Nuclear Information System (INIS)

    Thompson, I.M.; Whittlesey, G.C.; Slovis, T.L.; Chang, C.H.; Cullen, M.L.; Philippart, A.I.; Stockmann, P.S.; Adkins, E.S.; Klein, M.D.

    1997-01-01

    Background. Bronchography is occasionally needed for the evaluation and management of some congenital pulmonary anomalies as well as some acquired diseases, usually of the tracheo- bronchial tree. There is currently no effective, approved contrast agent for this imaging tech- nique. Objective. We evaluated five agents (barium sulfate, iohexol, propyliodone oily, propyliodone aqueous, and perflubron) in terms of image quality, histologic changes, and effects on hemodynamics, blood gases, and standard laboratory tests in New Zealand White rabbits. Materials and methods. Animals were anesthetized and intubated. Each contrast agent (0.25 ml/kg) was administered intratracheally. Three animals in each group had intravenous lines placed for blood sampling and blood pressure monitoring and were sacrificed at 1 h. An additional three animals for each agent were sacrificed at 24 h and 1 week after imaging. Blood samples were taken immediately before contrast instillation and at 1 h postbronchography. Fluoroscopic images were recorded on standard VHS video tape and evaluated in blind fashion. Segments of lung tissue and bronchi were obtained for histologic examination. Results. Necrosis and/or inflammatory infiltrates were noted in 78 % of the bronchograms performed with propyliodone aqueous, 67 % with propyliodone oily, 55 % with perflubron, and 33 % with iohexol 120, 240 and 350. No histologic damage was observed with barium. The propyliodones gave the best-quality imaging results and the most histologic changes. Iohexol, in any concentration, gave the least acceptable images and a moderate number of histologic changes. Barium sulfate demonstrated acceptable images with virtually no histologic changes. Conclusion. From the histologic and imaging results, barium is the best available contrast material for bronchography. (orig.). With 6 figs., 4 tabs

  15. Double contrast arthrography of the shoulder

    International Nuclear Information System (INIS)

    Gasparini, D.

    1991-01-01

    From 1980 to 1989 the author performed 481 double-contrast arthrographic examinations of the shoulder (DCSA). A hundred and forty-two complete and 46 partial rotator cuff tears were demonstrated; 68 of them underwent surgical exploration. Results confirmed DCSA capabilities in detecting both their location (100%) and size (95%). Moreover, thickness (89%) and erosions (94%) in tendon edges and surfaces were demonstrated - that is, all the qualitative information needed to depict degenerative processes. Such evidence may also affect treatment planning

  16. Iodinated contrast agent-induced nephropathy

    International Nuclear Information System (INIS)

    Erley, C.

    2007-01-01

    Contrast-induced nephropathy (CIN) is a well-known complication of therapeutic and diagnostic procedures requiring contrast administration and accounts for 10% of acute renal failure in hospitalized patients. Although the incidence of this complication is relatively low, its consequences can be catastrophic. The development of CIN is associated with increased length of hospital stay, an increased requirement for acute dialysis, and an increased risk of death. Preexisting renal dysfunction, age, diabetes, congestive heart failure, and volume of administered contrast are all associated with a risk of developing CIN. Despite a large number of clinical trials that have evaluated prophylaxis strategies for CIN, no uniform strategies have been developed so far. The use of N-acetyl-L-cysteine (NAC) or theophylline in specific subgroups of patients has been shown to reduce dialysis requirement and mortality in patients undergoing angiographic procedures. Hemofiltration has also shown positive results. In this review we will discuss the epidemiology and the risk factors for CIN and the evidence for commonly employed prophylaxis strategies, and we will provide general recommendations with respect to CIN prevention and management. A practicable strategy to prevent CIN includes: correct identification of individuals at greatest risk, thorough evaluation of whether other diagnostic maneuvers could be employed instead (i.e., sonography), application of low-osmolar contrast media at the minimum acceptable dose, stopping potential nephrotoxic drugs (NSAID), hydration with sodium chloride 0.9% 1 ml/kg per h i.v. 12 h before and after CM application, administration of acetylcysteine 600 mg twice the day before and after (in cases of emergency investigation and high-risk patients 1200 mg i.v.), and theophylline (250-350 mg) the day before and the day after CM application (in cases of emergency investigation 5 mg/kg i.v.). (orig.) [de

  17. Contrast media properties in interventional radiology

    International Nuclear Information System (INIS)

    Laerum, F.; Enge, I.

    1989-01-01

    Potential hazards of the use of contrast media (CM) in interventional radiology are analyzed by looking into each procedure regarding interactions of CM with pharmaceutical additives, with technical equipment possibly affecting CM stability, and special local or systemic demands related to the procedure. Also the impact of these factors upon the physiological mechanisms are taken into account. (H.W.). 32 refs.; 4 figs.; 2 tabs

  18. High contrast laser marking of alumina

    International Nuclear Information System (INIS)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; Val, J. del; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-01-01

    Highlights: • Laser marking of alumina using near infrared (NIR) lasers was experimentally analyzed. • Color change produced by NIR lasers is due to thermally induced oxygen vacancies. • Laser marking results obtained using NIR lasers and green laser are compared. • High contrast marks on alumina were achieved. - Abstract: Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks

  19. High contrast computed tomography with synchrotron radiation

    Science.gov (United States)

    Itai, Yuji; Takeda, Tohoru; Akatsuka, Takao; Maeda, Tomokazu; Hyodo, Kazuyuki; Uchida, Akira; Yuasa, Tetsuya; Kazama, Masahiro; Wu, Jin; Ando, Masami

    1995-02-01

    This article describes a new monochromatic x-ray CT system using synchrotron radiation with applications in biomedical diagnosis which is currently under development. The system is designed to provide clear images and to detect contrast materials at low concentration for the quantitative functional evaluation of organs in correspondence with their anatomical structures. In this system, with x-ray energy changing from 30 to 52 keV, images can be obtained to detect various contrast materials (iodine, barium, and gadolinium), and K-edge energy subtraction is applied. Herein, the features of the new system designed to enhance the advantages of SR are reported. With the introduction of a double-crystal monochromator, the high-order x-ray contamination is eliminated. The newly designed CCD detector with a wide dynamic range of 60 000:1 has a spatial resolution of 200 μm. The resulting image quality, which is expected to show improved contrast and spatial resolution, is currently under investigation.

  20. V1 mechanisms underlying chromatic contrast detection

    Science.gov (United States)

    Hass, Charles A.

    2013-01-01

    To elucidate the cortical mechanisms of color vision, we recorded from individual primary visual cortex (V1) neurons in macaque monkeys performing a chromatic detection task. Roughly 30% of the neurons that we encountered were unresponsive at the monkeys' psychophysical detection threshold (PT). The other 70% were responsive at threshold but on average, were slightly less sensitive than the monkey. For these neurons, the relationship between neurometric threshold (NT) and PT was consistent across the four isoluminant color directions tested. A corollary of this result is that NTs were roughly four times lower for stimuli that modulated the long- and middle-wavelength sensitive cones out of phase. Nearly one-half of the neurons that responded to chromatic stimuli at the monkeys' detection threshold also responded to high-contrast luminance modulations, suggesting a role for neurons that are jointly tuned to color and luminance in chromatic detection. Analysis of neuronal contrast-response functions and signal-to-noise ratios yielded no evidence for a special set of “cardinal color directions,” for which V1 neurons are particularly sensitive. We conclude that at detection threshold—as shown previously with high-contrast stimuli—V1 neurons are tuned for a diverse set of color directions and do not segregate naturally into red–green and blue–yellow categories. PMID:23446689

  1. Contrast bolus technique with rapid CT scanning

    International Nuclear Information System (INIS)

    Arnold, H.; Kuehne, D.; Rohr, W.; Heller, M.

    1981-01-01

    Twenty-three patients complying with the clinical criteria for brain death were studied by contrast-enhanced CT. In all but one, the great intracranial vessels escaped visualization; accordingly, angiography demonstrated cerebral circulatory arrest. In the remaining case, faint enhancement of the circle of Willis corresponded to angiographic demonstration of the proximal segments of cerebral arteris. Neither in normal brain nor in dead brain did slow CT scanning disclose any postcontrast increase in parenchymal attenuation. An improved technique is proposed to demonstrate the transit of the contrast bolus by rapid CT with image splitting. If cerebral blood flow is preserved, the grey and white matter will enhance significantly following administration of contrast medium. Vice versa, the absence of enhancement confirms brain death, even in instances in which the great cerebral vessels are obscured by hemorrhage or other extensive lesions. Two additional cases of brain death were evaluated by rapid CT scanning. As to brain death, the technique obviates the need for angiography or radionuclide angiography, usually applied in prospective organ donors, because its informative content is superior to that of either method. The CT technique described affords a reliable and safe diagnosis of brain death, and can be interpreted easily. (orig.)

  2. Nephrotoxicity of cyclosporin A and contrast media

    International Nuclear Information System (INIS)

    Thomsen, H.S.; Larsen, S.; Skaarup, P.; Hemmingsen, L.; Dieperink, H.; Golman, K.; Herlev Hospital; Herlev Hospital; Centralsygehuset, Nykoebing Falster; Odense Sygehus; Malmoe Allmaenna Sjukhus

    1989-01-01

    Urine profiles (albumin, glucose, NAG, LDH, GGT and sodium) were followed for 22 h or 8 days after intravenous injection of diatrizoate, iohexol or saline in 30 adult Wistar rats in which nephrotoxicity was induced by daily peroral administration of 25 mg/kg body weight cyclosporin A over a 14-day period. Another 10 rats which had the vehicle of the cyclosporin A solution (placebo) and saline injected intravenously served as controls. The effect of iohexol and saline on the albumin excretion was similar, whereas diatrizoate increased it significantly. Both contrast media caused significantly increased excretion of all three enzymes. The contrast media had no effect on the excretion of glucose and sodium. Except for the fact that the excretion of NAG was significantly higher following iohexol than following diatrizoate 24 to 46 h after injection no significant differences between the two media were found from 24 h after injection among the rats given cyclosporin A. No contrast medium related changes were found by light microscopy of the kidneys. Neither iohexol nor diatrizoate potentiate acute cyclosporin A nephrotoxicity. (orig.)

  3. Radiologic findings of double contrast knee arthrography

    International Nuclear Information System (INIS)

    Choi, Hye Ran; Ahn, Byeong Yeob; Kim, Mi Young; Lee, So Hyun; Suh, Chang Hae; Chung, Won Kyun

    1990-01-01

    The double contrast arthrography of the knee is a highly accurate diagnostic modality in wide rage of the clinical disorders of the knee. It allows radiological assessment of the menisci, the articular cartilages, the synovium and the ligaments. The double contrast knee arthrography was performed in 356 cases at Inha hospital for about 3 years from June 1986 to June 1989. Among them, 115 cases were abnormal, and were analyzed clinically and radiologically with the back ground of the operative finding. The results were as follows ; 1. Of the 115 cases, male were 77 and female 38. Male exceeds female in the ratio of 2 : 1. 2. The age group of 20 - 39 years was commonly involved (60%). 3. The right knee was more commonly involved than the left and the medial meniscus tear was more common (61%). The posterior horn of the meniscus was more frequently torn than the other parts of the meniscus (42%). 4. The incidence of the bucket-handle tear was the most frequent (33%). 5. The cases of the popliteal cyst were 16 (13.9%), and the combined meniscus tears were in 4 cases (25%). 6. The numbers of the discoid meniscus were 9 (7.8%), and all were present in the lateral meniscus, and combined tears were in 4 cases (44.4%). 7. The diagnostic accuracy of the double contrast knee arthrogram was 82.7% compared with operative finding. The false positive examination were 17.3%

  4. Choice and technique of negative contrast in double contrast roentgenography of the stomach

    International Nuclear Information System (INIS)

    Pomakov, P.; Tomov, A.; Popsavov, P.; Tirolska, M.

    1993-01-01

    A comparative study of 8 negative contrast media is performed in 720 patients undergoing double-contrast abdominal biomedical radiography. The following preparations and methods are compared: Unibarit (Roelm, Pharma), CO 2 granulate (Nicholas), Sandosten Calcium + Calcium gluconicum (Sandoz, Pharmachim), Kalinor (Nordmark), dust variation of p. Rivieri, conducted aerophagy, stomach-tube, 'Echo'-lemonade. The average size of the gas bubble of the fornix (cm 2 ), the average volume of the gas collection (ml) and the relationship between the area of the negative contrast image (cm 2 ) and the volume of the gas (ml) is given. Some possibilities for production of domestic negative contrast media are also discussed. 2 tabs., 18 refs. (orig.)

  5. Spectral triangulation molecular contrast optical coherence tomography with indocyanine green as the contrast agent

    OpenAIRE

    Yang, Changhuei; McGuckin, Laura E. L.; Simon, John D.; Choma, Michael A.; Applegate, Brian E.; Izatt, Joseph A.

    2004-01-01

    We report a new molecular contrast optical coherence tomography (MCOCT) implementation that profiles the contrast agent distribution in a sample by measuring the agent's spectral differential absorption. The method, spectra triangulation MCOCT, can effectively suppress contributions from spectrally dependent scatterings from the sample without a priori knowledge of the scattering properties. We demonstrate molecular imaging with this new MCOCT modality by mapping the distribution of indocyani...

  6. Comparative study of pneumocystography, positive contrast cystography and double contrast cystography in dogs

    International Nuclear Information System (INIS)

    Thibaut, J.; Parada, E.; Vargas, L.; Deppe, R.; Born, R.

    1997-01-01

    In order to compare three radiographic techniques: pneumocystography, positive contrast cystography and double contrast cystography, three series of 24 radiographs each in lateral and ventrodorsal projections were made. Six healthy adult male dogs with weight ranging between 7 and 16 kg were used. Food was withheld for 24 hours and two enemas were made before the series of radiographs were taken. Dogs were anaesthetized with sodium thiopental (20 mg/kg i.v.). The contrast medium was introduced through a urethral catheter. Pneumocystography was performed in the first series introducing air (10 ml/kg) in the bladder. Positive contrast cystography was performed in the second series introducing Hypaque M-60% diluted, contributing 100 mg of iodine per ml (10 ml/kg). In the double contrast cystography Hypaque M-60% diluted (10 ml) was introduced, in concentration of 150 mg of iodine per ml. Then air was introduced (10 ml/kg) through a catheter. Plates were taken in both projections at 1 and 10 minutes for each technique. The radiographic plates of each series were analized comparing the characteristics of radiographic density, outline and size. In neumocystography, positive contrast and double contrast cystography, the radiographic density was predominantly low, high and intermediate, respectively. The radiographic outline was mainly regular for the three techniques. With respect to bladder size, there was a decrease of height and an increase of length and width at 10 minutes. Comparing these three radiographic techniques, it can be concluded that the one that best outlines the bladder mucosa is double contrast. Pneumocystography provides the best image for opaque structures and cystography best shows the position of the urinary bladder [es

  7. The NOD2 p.Leu1007fsX1008 mutation (rs2066847 is a stronger predictor of the clinical course of Crohn's disease than the FOXO3A intron variant rs12212067.

    Directory of Open Access Journals (Sweden)

    Fabian Schnitzler

    Full Text Available Very recently, a sub-analysis of genome-wide association scans revealed that the non-coding single nucleotide polymorphism (SNP rs12212067 in the FOXO3A gene is associated with a milder course of Crohn's disease (CD (Cell 2013;155:57-69. The aim of our study was to evaluate the clinical value of the SNP rs12212067 in predicting the severity of CD by correlating CD patient genotype status with the most relevant complications of CD such as stenoses, fistulas, and CD-related surgery.We genotyped 550 CD patients for rs12212067 (FOXO3A and the three common CD-associated NOD2 mutations rs2066844, rs2066847, and rs2066847 and performed genotype-phenotype analyses.No significant phenotypic differences were found between the wild-type genotype TT of the FOXO3A SNP rs12212067 and the minor genotypes TG and GG independently from NOD2 variants. The allele frequency of the minor G allele was 12.7%. Age at diagnosis, disease duration, body mass index, surgery rate, stenoses, fistula, need for immunosuppressive therapy, and disease course were not significantly different. In contrast, the NOD2 mutant p.Leu1007fsX1008 (rs2066847 was highly associated with penetrating CD (p = 0.01, the development of fistulas (p = 0.01 and stenoses (p = 0.01, and ileal disease localization (p = 0.03. Importantly, the NOD2 SNP rs2066847 was a strong separator between an aggressive and a mild course of CD (p = 2.99×10(-5, while the FOXO3A SNP rs12212067 did not separate between mild and aggressive CD behavior in our cohort (p = 0.35. 96.2% of the homozygous NOD2 p.Leu1007fsX1008 carriers had an aggressive disease behavior compared to 69.3% of the patients with the NOD2 wild-type genotype (p = 0.007.In clinical practice, the NOD2 variant p.Leu1007fsX1008 (rs2066847, in particular in homozygous form, is a much stronger marker for a severe clinical phenotype than the FOXO3A rs12212067 SNP for a mild disease course on an individual patient level despite

  8. The NOD2 p.Leu1007fsX1008 mutation (rs2066847) is a stronger predictor of the clinical course of Crohn's disease than the FOXO3A intron variant rs12212067.

    Science.gov (United States)

    Schnitzler, Fabian; Friedrich, Matthias; Wolf, Christiane; Angelberger, Marianne; Diegelmann, Julia; Olszak, Torsten; Beigel, Florian; Tillack, Cornelia; Stallhofer, Johannes; Göke, Burkhard; Glas, Jürgen; Lohse, Peter; Brand, Stephan

    2014-01-01

    Very recently, a sub-analysis of genome-wide association scans revealed that the non-coding single nucleotide polymorphism (SNP) rs12212067 in the FOXO3A gene is associated with a milder course of Crohn's disease (CD) (Cell 2013;155:57-69). The aim of our study was to evaluate the clinical value of the SNP rs12212067 in predicting the severity of CD by correlating CD patient genotype status with the most relevant complications of CD such as stenoses, fistulas, and CD-related surgery. We genotyped 550 CD patients for rs12212067 (FOXO3A) and the three common CD-associated NOD2 mutations rs2066844, rs2066847, and rs2066847 and performed genotype-phenotype analyses. No significant phenotypic differences were found between the wild-type genotype TT of the FOXO3A SNP rs12212067 and the minor genotypes TG and GG independently from NOD2 variants. The allele frequency of the minor G allele was 12.7%. Age at diagnosis, disease duration, body mass index, surgery rate, stenoses, fistula, need for immunosuppressive therapy, and disease course were not significantly different. In contrast, the NOD2 mutant p.Leu1007fsX1008 (rs2066847) was highly associated with penetrating CD (p = 0.01), the development of fistulas (p = 0.01) and stenoses (p = 0.01), and ileal disease localization (p = 0.03). Importantly, the NOD2 SNP rs2066847 was a strong separator between an aggressive and a mild course of CD (p = 2.99×10(-5)), while the FOXO3A SNP rs12212067 did not separate between mild and aggressive CD behavior in our cohort (p = 0.35). 96.2% of the homozygous NOD2 p.Leu1007fsX1008 carriers had an aggressive disease behavior compared to 69.3% of the patients with the NOD2 wild-type genotype (p = 0.007). In clinical practice, the NOD2 variant p.Leu1007fsX1008 (rs2066847), in particular in homozygous form, is a much stronger marker for a severe clinical phenotype than the FOXO3A rs12212067 SNP for a mild disease course on an individual patient level despite its

  9. Fluorescence measurements show stronger cold inhibition of photosynthetic light reactions in Scots pine compared to Norway spruce as well as during spring compared to autumn.

    Science.gov (United States)

    Linkosalo, Tapio; Heikkinen, Juha; Pulkkinen, Pertti; Mäkipää, Raisa

    2014-01-01

    We studied the photosynthetic activity of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst) in relation to air temperature changes from March 2013 to February 2014. We measured the chlorophyll fluorescence of approximately 50 trees of each species growing in southern Finland. Fluorescence was measured 1-3 times per week. We began by measuring shoots present in late winter (i.e., March 2013) before including new shoots once they started to elongate in spring. By July, when the spring shoots had achieved similar fluorescence levels to the older ones, we proceeded to measure the new shoots only. We analyzed the data by fitting a sigmoidal model containing four parameters to link sliding averages of temperature and fluorescence. A parameter defining the temperature range over which predicted fluorescence increased most rapidly was the most informative with in describing temperature dependence of fluorescence. The model generated similar fluorescence patterns for both species, but differences were observed for critical temperature and needle age. Down regulation of the light reaction was stronger in spring than in autumn. Pine showed more conservative control of the photosynthetic light reactions, which were activated later in spring and more readily attenuated in autumn. Under the assumption of a close correlation of fluorescence and photosynthesis, spruce should therefore benefit more than pine from the increased photosynthetic potential during warmer springs, but be more likely to suffer frost damage with a sudden cooling following a warm period. The winter of 2013-2014 was unusually mild and similar to future conditions predicted by global climate models. During the mild winter, the activity of photosynthetic light reactions of both conifers, especially spruce, remained high. Because light levels during winter are too low for photosynthesis, this activity may translate to a net carbon loss due to respiration.

  10. Fluorescence measurements show stronger cold inhibition of photosynthetic light reactions in Scots pine compared to Norway spruce as well as during spring compared to autumn

    Directory of Open Access Journals (Sweden)

    Tapio eLinkosalo

    2014-06-01

    Full Text Available We studied the photosynthetic activity of Scots pine (Pinus sylvestris L. and Norway spruce (Picea abies [L.] Karst in relation to air temperature changes from March 2013 to February 2014. We measured the chlorophyll fluorescence of approximately 50 trees of each species growing in southern Finland. Fluorescence was measured 13 times per week. We began by measuring shoots present in late winter (i.e., March 2013 before including new shoots once they started to elongate in spring. By July, when the spring shoots had achieved similar fluorescence levels to the older ones, we proceeded to measure the new shoots only.We analysed the data by fitting a sigmoidal model containing four parameters to link sliding averages of temperature and fluorescence. A parameter defining the temperature range over which predicted fluorescence increased most rapidly was the most informative with in describing temperature dependence of fluorescence.The model generated similar fluorescence patterns for both species, but differences were observed for critical temperature and needle age. Down regulation of the light reaction was stronger in spring than in autumn. Pine showed more conservative control of the photosynthetic light reactions, which were activated later in spring and more readily attenuated in autumn. Under the assumption of a close correlation of fluorescence and photosynthesis, spruce should therefore benefit more than pine from the increased photosynthetic potential during warmer springs, but be more likely to suffer frost damage with a sudden cooling following a warm period. The winter of 20132014 was unusually mild and similar to future conditions predicted by global warming models. During the mild winter, the activity of photosynthetic light reactions of both conifers, especially spruce, remained high. Because light levels during winter are too low for photosynthesis, this activity may translate to a net carbon loss due to respiration.

  11. Stronger default mode network connectivity is associated with poorer clinical insight in youth at ultra high-risk for psychotic disorders.

    Science.gov (United States)

    Clark, Sarah V; Mittal, Vijay A; Bernard, Jessica A; Ahmadi, Aral; King, Tricia Z; Turner, Jessica A

    2018-03-01

    Impaired clinical insight (CI) is a common symptom of psychotic disorders and a promising treatment target. However, to date, our understanding of how variability in CI is tied to underlying brain dysfunction in the clinical high-risk period is limited. Developing a stronger conception of this link will be a vital first step for efforts to determine if CI can serve as a useful prognostic indicator. The current study investigated whether variability in CI is related to major brain networks in adolescents and young adults at ultra high-risk (UHR) of developing psychosis. Thirty-five UHR youth were administered structured clinical interviews as well as an assessment for CI and underwent resting-state magnetic resonance imaging scans. Functional connectivity was calculated in the default mode network (DMN) and fronto-parietal network (FPN), two major networks that are dysfunctional in psychosis and are hypothesized to affect insight. Greater DMN connectivity between the posterior cingulate/precuneus and ventromedial prefrontal cortex (DMN) was related to poorer CI (R 2 =0.399). There were no significant relationships between insight and the FPN. This is the first study to relate a major brain network to clinical insight before the onset of psychosis. Findings are consistent with evidence if a hyperconnected DMN in schizophrenia and UHR, and similar to a previous study of insight and connectivity in schizophrenia. Results suggest that a strongly connected DMN may be related to poor self-awareness of subthreshold psychotic symptoms in UHR adolescents and young adults. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Analogues of the Frog-skin Antimicrobial Peptide Temporin 1Tb Exhibit a Wider Spectrum of Activity and a Stronger Antibiofilm Potential as Compared to the Parental Peptide

    Science.gov (United States)

    Grassi, Lucia; Maisetta, Giuseppantonio; Maccari, Giuseppe; Esin, Semih; Batoni, Giovanna

    2017-04-01

    The frog skin-derived peptide Temporin 1Tb (TB) has gained increasing attention as novel antimicrobial agent for the treatment of antibiotic-resistant and/or biofilm-mediated infections. Nevertheless, such a peptide possesses a preferential spectrum of action against Gram-positive bacteria. In order to improve the therapeutic potential of TB, the present study evaluated the antibacterial and antibiofilm activities of two TB analogues against medically relevant bacterial species. Of the two analogues, TB_KKG6A has been previously described in the literature, while TB_L1FK is a new analogue designed by us through statistical-based computational strategies. Both TB analogues displayed a faster and stronger bactericidal activity than the parental peptide, especially against Gram-negative bacteria in planktonic form. Differently from the parental peptide, TB_KKG6A and TB_L1FK were able to inhibit the formation of Staphylococcus aureus biofilms by more than 50% at 12 μM, while only TB_KKG6A prevented the formation of Pseudomonas aeruginosa biofilms at 24 μM. A marked antibiofilm activity against preformed biofilms of both bacterial species was observed for the two TB analogues when used in combination with EDTA. Analysis of synergism at the cellular level suggested that the antibiofilm activity exerted by the peptide-EDTA combinations against mature biofilms might be due mainly to a disaggregating effect on the extracellular matrix in the case of S. aureus, and to a direct activity on biofilm-embedded cells in the case of P. aeruginosa. Both analogues displayed a low hemolytic effect at the active concentrations and, overall, TB_L1FK resulted less cytotoxic towards mammalian cells. Collectively, the results obtained demonstrated that subtle changes in the primary sequence of TB may provide TB analogues that, used alone or in combination with adjuvant molecules such as EDTA, exhibit promising features against both planktonic and biofilm cells of medically relevant

  13. The effect of transcranial direct current stimulation on contrast sensitivity and visual evoked potential amplitude in adults with amblyopia.

    Science.gov (United States)

    Ding, Zhaofeng; Li, Jinrong; Spiegel, Daniel P; Chen, Zidong; Chan, Lily; Luo, Guangwei; Yuan, Junpeng; Deng, Daming; Yu, Minbin; Thompson, Benjamin

    2016-01-14

    Amblyopia is a neurodevelopmental disorder of vision that occurs when the visual cortex receives decorrelated inputs from the two eyes during an early critical period of development. Amblyopic eyes are subject to suppression from the fellow eye, generate weaker visual evoked potentials (VEPs) than fellow eyes and have multiple visual deficits including impairments in visual acuity and contrast sensitivity. Primate models and human psychophysics indicate that stronger suppression is associated with greater deficits in amblyopic eye contrast sensitivity and visual acuity. We tested whether transcranial direct current stimulation (tDCS) of the visual cortex would modulate VEP amplitude and contrast sensitivity in adults with amblyopia. tDCS can transiently alter cortical excitability and may influence suppressive neural interactions. Twenty-one patients with amblyopia and twenty-seven controls completed separate sessions of anodal (a-), cathodal (c-) and sham (s-) visual cortex tDCS. A-tDCS transiently and significantly increased VEP amplitudes for amblyopic, fellow and control eyes and contrast sensitivity for amblyopic and control eyes. C-tDCS decreased VEP amplitude and contrast sensitivity and s-tDCS had no effect. These results suggest that tDCS can modulate visual cortex responses to information from adult amblyopic eyes and provide a foundation for future clinical studies of tDCS in adults with amblyopia.

  14. The contrasting roles of inflammasomes in cancer

    Science.gov (United States)

    He, Qin; Fu, Yu; Tian, Dean; Yan, Wei

    2018-01-01

    Chronic inflammation plays a decisive role at different stages of cancer development. Inflammasomes are oligomeric protein complexes activated in response to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). PAMPs and DAMPs are released from infected cells, tumors and damaged tissues. Inflammasomes activate and release inflammatory cytokines such as IL-1β and IL-18. The various inflammasomes and inflammatory cytokines and chemokines play contrasting roles in cancer development and progression. In this review, we describe the roles of different inflammasomes in lung, breast, gastric, liver, colon, and prostate cancers and in glioblastomas.

  15. Molecular imaging with targeted contrast ultrasound.

    Science.gov (United States)

    Piedra, Mark; Allroggen, Achim; Lindner, Jonathan R

    2009-01-01

    Molecular imaging with contrast-enhanced ultrasound uses targeted microbubbles that are retained in diseased tissue. The resonant properties of these microbubbles produce acoustic signals in an ultrasound field. The microbubbles are targeted to diseased tissue by using certain chemical constituents in the microbubble shell or by attaching disease-specific ligands such as antibodies to the microbubble. In this review, we discuss the applications of this technique to pathological states in the cerebrovascular system including atherosclerosis, tumor angiogenesis, ischemia, intravascular thrombus, and inflammation. Copyright 2009 S. Karger AG, Basel.

  16. Contrast enhanced cartilage imaging: Comparison of ionic and non-ionic contrast agents

    International Nuclear Information System (INIS)

    Wiener, Edzard; Woertler, Klaus; Weirich, Gregor; Rummeny, Ernst J.; Settles, Marcus

    2007-01-01

    Our objective was to compare relaxation effects, dynamics and spatial distributions of ionic and non-ionic contrast agents in articular cartilage at concentrations typically used for direct MR arthrography at 1.5 T. Dynamic MR-studies over 11 h were performed in 15 bovine patella specimens. For each of the contrast agents gadopentetate dimeglumine, gadobenate dimeglumine, gadoteridol and mangafodipir trinatrium three patellae were placed in 2.5 mmol/L contrast solution. Simultaneous measurements of T 1 and T 2 were performed every 30 min using a high-spatial-resolution 'MIX'-sequence. T 1 , T 2 and ΔR 1 , ΔR 2 profile plots across cartilage thickness were calculated to demonstrate the spatial and temporal distributions. The charge is one of the main factors which controls the amount of the contrast media diffusing into intact cartilage, but independent of the charge, the spatial distribution across cartilage thickness remains highly inhomogeneous even after 11 h of diffusion. The absolute ΔR 2 -effect in cartilage is at least as large as the ΔR 1 -effect for all contrast agents. Maximum changes were 5-12 s -1 for ΔR 1 and 8-15 s -1 for ΔR 2 . This study indicates that for morphologically intact cartilage only the amount of contrast agents within cartilage is determined by the charge but not the spatial distribution across cartilage thickness. In addition, ΔR 2 can be considered for quantification of contrast agent concentrations, since it is of the same magnitude and less time consuming to measure than ΔR 1

  17. High contrast laser marking of alumina

    Science.gov (United States)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; del Val, J.; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-05-01

    Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks.

  18. Osteoblastic Metastases Mimickers on Contrast Enhanced CT

    Directory of Open Access Journals (Sweden)

    Fahad Al-Lhedan

    2017-01-01

    Full Text Available Secondary osseous involvement in lymphoma is more common compared to primary bone lymphoma. The finding of osseous lesion can be incidentally discovered during the course of the disease. However, osseous metastases are infrequently silent. Detection of osseous metastases is crucial for accurate staging and optimal treatment planning of lymphoma. The aim of imaging is to identify the presence and extent of osseous disease and to assess for possible complications such as pathological fracture of the load-bearing bones and cord compression if the lesion is spinal. We are presenting two patients with treated lymphoma who were in complete remission. On routine follow-up contrast enhanced CT, there were new osteoblastic lesions in the spine worrisome for metastases. Additional studies were performed for further evaluation of both of them which did not demonstrate any corresponding suspicious osseous lesion. The patients have a prior history of chronic venous occlusive thrombosis that resulted in collaterals formation. Contrast enhancement of the vertebral body marrow secondary to collaterals formation and venous flow through the vertebral venous plexus can mimic the appearance of spinal osteoblastic metastases.

  19. Novel contrast agent for liver and spleen

    International Nuclear Information System (INIS)

    Seltzer, S.E.; Blau, M.; Adams, D.F.; Janoff, A.; Minchey, S.

    1991-01-01

    This paper determines whether the biodistribution and imaging characteristics of a liposome-encapsulated contrast agent, iotrolan-carrying interdigitation fusion (IF) vesicles, were acceptable for a liver-spleen CT contrast agent. IF vesicles with iotrolan in their aqueous phase were prepared by fusing small unilamellar liposomes into larger vesicles. The iodine-to-lipid ratio was 4.7. Biodistribution was measured with I-125 iotrolan-labeled IF vesicles in rats. CT imaging (Somatom Plus, Siemens Medical Systems) was performed in dogs. At the lowest dose (10 mg of iodine and 2.1 mg of lipid per kilogram) 72% of the ID was in the liver, 5% in spleen, and 1% in lungs at 1 hour. At the highest dose, (1,000 mg of iodine and 212 mg of lipid per kilogram), liver values were 68% ID, while spleen rose to 18%, lung 5%. Liver and spleen values stayed at peak for 24 hours then fell; the half-life was 6 days. In dogs, liver and spleen enhancement at 1 hour averaged 652 and 256 HU above baseline per gram of iodine per kilogram, respectively

  20. Magnetic resonance perfusion imaging without contrast media

    International Nuclear Information System (INIS)

    Martirosian, Petros; Graf, Hansjoerg; Schick, Fritz; Boss, Andreas; Schraml, Christina; Schwenzer, Nina F.; Claussen, Claus D.

    2010-01-01

    Principles of magnetic resonance imaging techniques providing perfusion-related contrast weighting without administration of contrast media are reported and analysed systematically. Especially common approaches to arterial spin labelling (ASL) perfusion imaging allowing quantitative assessment of specific perfusion rates are described in detail. The potential of ASL for perfusion imaging was tested in several types of tissue. After a systematic comparison of technical aspects of continuous and pulsed ASL techniques the standard kinetic model and tissue properties of influence to quantitative measurements of perfusion are reported. For the applications demonstrated in this paper a flow-sensitive alternating inversion recovery (FAIR) ASL perfusion preparation approach followed by true fast imaging with steady precession (true FISP) data recording was developed and implemented on whole-body scanners operating at 0.2, 1.5 and 3 T for quantitative perfusion measurement in various types of tissue. ASL imaging provides a non-invasive tool for assessment of tissue perfusion rates in vivo. Images recorded from kidney, lung, brain, salivary gland and thyroid gland provide a spatial resolution of a few millimetres and sufficient signal to noise ratio in perfusion maps after 2-5 min of examination time. Newly developed ASL techniques provide especially high image quality and quantitative perfusion maps in tissues with relatively high perfusion rates (as also present in many tumours). Averaging of acquisitions and image subtraction procedures are mandatory, leading to the necessity of synchronization of data recording to breathing in abdominal and thoracic organs. (orig.)

  1. Adaptive multiscale processing for contrast enhancement

    Science.gov (United States)

    Laine, Andrew F.; Song, Shuwu; Fan, Jian; Huda, Walter; Honeyman, Janice C.; Steinbach, Barbara G.

    1993-07-01

    This paper introduces a novel approach for accomplishing mammographic feature analysis through overcomplete multiresolution representations. We show that efficient representations may be identified from digital mammograms within a continuum of scale space and used to enhance features of importance to mammography. Choosing analyzing functions that are well localized in both space and frequency, results in a powerful methodology for image analysis. We describe methods of contrast enhancement based on two overcomplete (redundant) multiscale representations: (1) Dyadic wavelet transform (2) (phi) -transform. Mammograms are reconstructed from transform coefficients modified at one or more levels by non-linear, logarithmic and constant scale-space weight functions. Multiscale edges identified within distinct levels of transform space provide a local support for enhancement throughout each decomposition. We demonstrate that features extracted from wavelet spaces can provide an adaptive mechanism for accomplishing local contrast enhancement. We suggest that multiscale detection and local enhancement of singularities may be effectively employed for the visualization of breast pathology without excessive noise amplification.

  2. Contrast-induced nephropathy: risks, pathogenetic, prevention

    International Nuclear Information System (INIS)

    Paskalev, D.; Balev, B.

    2006-01-01

    Full text: The aim of the presentation is to review the contrast induced nephropathy ? nature, mechanisms of development, risk factors. Summary of the most important ways of prevention, diagnostics and treatment. The definition of CIN according the European Association of Urogenital Radiology is: 'A condition, in which renal function is impaired (elevation of serum creatinine with more than 25% or 44 μmol/l above the initial level) due to intravasal application of contrast media (CM) within 3 days following the application and when no other etiology factors are present'. We summarize the main risk factors of developing CIN - renal failure, diabetic nephropathy, dehydration, congestive heart failure, high blood pressure, age above 70 yrs, nephrotoxic medicines. The most effective ways of preventing CIN are the good hydratation of the patients and the usage of low-osmolar or iso-osmolar CM. Therapeutic treatment is with no proven preventive effect and currently is not routinely recommended. An early hem dialysis does not decrease the risk level of CIN development in patients with chronic renal failure (CRF). In such patients complete elimination of CM is achieved only after several hem dialyses. Hem filtration reliably decreases the risk of CIN in CRF patients, but is expensive and not widely available. We present a case from our hospital of a patient with diabetic nephropathy, who developed CIN following a coronary angiography

  3. Halftoning for high-contrast imaging

    Directory of Open Access Journals (Sweden)

    Kasper M.

    2011-07-01

    Full Text Available High-contrast instruments, such as SPHERE (upcoming planet finder instrument for the ESO-VLT, or EPICS (planet hunter project for the future E-ELT, will require customized components with spatially varying transmission (e.g. coronagraphs, optical components that reduce the contrast between a companion and its parent star. The goal of these sub-systems is to control the spatial transmission, either in a pupil plane (pupil apodization, or in a focal plane of the instrument (occulting mask, i.e. low-frequency filter. Reliably producing components with spatially varying transmission is not trivial, and different techniques have been already investigated for application to astronomy (e.g. metal deposition with spatially-varying thickness, or high-energy beam sensitive glass using e-beam lithography. We present some results related to the recent development of components with spatially varying transmission using a relatively simple technique analogous to the digital halftoning process used for printing applications.

  4. Quantitative contrast-enhanced optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Winetraub, Yonatan; SoRelle, Elliott D. [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Liba, Orly [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Zerda, Adam de la [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States)

    2016-01-11

    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.

  5. MRI contrast enhancement using Magnetic Carbon Nanoparticles

    Science.gov (United States)

    Chaudhary, Rakesh P.; Kangasniemi, Kim; Takahashi, Masaya; Mohanty, Samarendra K.; Koymen, Ali R.; Department of Physics, University of Texas at Arlington Team; University of Texas Southwestern Medical Center Team

    2014-03-01

    In recent years, nanotechnology has become one of the most exciting forefront fields in cancer diagnosis and therapeutics such as drug delivery, thermal therapy and detection of cancer. Here, we report development of core (Fe)-shell (carbon) nanoparticles with enhanced magnetic properties for contrast enhancement in MRI imaging. These new classes of magnetic carbon nanoparticles (MCNPs) are synthesized using a bottom-up approach in various organic solvents, using the electric plasma discharge generated in the cavitation field of an ultrasonic horn. Gradient echo MRI images of well-dispersed MCNP-solutions (in tube) were acquired. For T2 measurements, a multi echo spin echo sequence was performed. From the slope of the 1/T2 versus concentration plot, the R2 value for different CMCNP-samples was measured. Since MCNPs were found to be extremely non-reactive, and highly absorbing in NIR regime, development of carbon-based MRI contrast enhancement will allow its simultaneous use in biomedical applications. We aim to localize the MCNPs in targeted tissue regions by external DC magnetic field, followed by MRI imaging and subsequent photothermal therapy.

  6. A new double contrast barium enema

    International Nuclear Information System (INIS)

    Park, Jun Sang; Cho, Won Sik; Lee, Sung Woo; Lee, Mun Gyu; Jeon, Jeong Dong; Jaun, Woo Ki; Han, Chung Yul

    1987-01-01

    A new technic of the barium enema was proposed for the better colonic double contrast study with the average 204ml of 50w/v% barium, applied to 109 serial patients. The barium was introduced to sigmoid colon, and then pushed to a mid transverse colon by the air insufflation through an enema syringe, a new device. An advance to cecum is accomplished by the air insufflation and/or the position change of the patient. The barium transfer method was developed for the best spot film exposure, through colon, by the position change of the patient, the tilting of the x-ray table and the air insufflation with the enema syringe. The mean angle of the x-ray table tilted was -10 .deg. at the beginning the barium enema till the barium sent past the splenic flexure, -15 . deg. for the best lateral view of rectum and -18 .deg. for the bet prone PA view of rectosigmoid colon. This was a simple, better and economic double contrast barium enema for the cooperative patients

  7. Synthesis of Laboratory Ultrasound Contrast Agents

    Directory of Open Access Journals (Sweden)

    Jaemin Oh

    2013-10-01

    Full Text Available Ultrasound Contrast Agents (UCAs were developed to maximize reflection contrast so that organs can be seen clearly in ultrasound imaging. UCAs increase the signal to noise ratio (SNR by linear and non-linear mechanisms and thus help more accurately visualize the internal organs and blood vessels. However, the UCAs on the market are not only expensive, but are also not optimized for use in various therapeutic research applications such as ultrasound-aided drug delivery. The UCAs fabricated in this study utilize conventional lipid and albumin for shell formation and perfluorobutane as the internal gas. The shape and density of the UCA bubbles were verified by optical microscopy and Cryo SEM, and compared to those of the commercially available UCAs, Definity® and Sonovue®. The size distribution and characteristics of the reflected signal were also analyzed using a particle size analyzer and ultrasound imaging equipment. Our experiments indicate that UCAs composed of spherical microbubbles, the majority of which were smaller than 1 um, were successfully synthesized. Microbubbles 10 um or larger were also identified when different shell characteristics and filters were used. These laboratory UCAs can be used for research in both diagnoses and therapies.

  8. Development of organic MRI contrast agents

    International Nuclear Information System (INIS)

    Hayashi, Hiroyuki; Sato, Yuichiro; Karasawa, Satoru; Koga, Noboru

    2008-01-01

    Described are trends of the development in the title since those agents with target properties are awaited for specific organ and regional MRI. The contrast agents alter the relaxation time of water proton to yield the enhanced contrast between organs and tissues with different water volumes. Nowadays Gd-complexes and nano-particle of superparamagnetic iron oxide (Fe(III)) are widely used for enhancing in clinic. Among organic compounds with paramagnetic spin, those possessing nitroxide radical like TEMPO- and PROXYL-radicals have been subject to development by their derivatization. High spin molecules conceivably affect the relaxivity, which, however, is found smaller per spin of synthesized triplet complexes than doublet ones. This has lead to basic approach for molecules restricting water movement due to their hydrogen bond like DNA as a model, for introducing many radicals in high molecular weight compounds, and their polymer, as one of which authors have developed a derivative of hyperbranched polymer (HPS)-TEMPO having the similar relaxivity to gadolinium-diethylenetiamine pentaacetid acid (Gd-DTPA) (R.T.)

  9. The Acquisition of Quantity Contrasts in Guina-ang Bontok

    Science.gov (United States)

    Aoyama, Katsura; Reid, Lawrence A.

    2016-01-01

    This study reports on the acquisition of quantity contrasts in Guina-ang Bontok, an indigenous language spoken in the Philippines. Four-year-old and 5-year-old children's perception and production of quantity contrasts were examined using a pair of names that contrast in the quantity of the medial nasal. Frequencies of the quantity contrast were…

  10. Generalized image contrast enhancement technique based on the Heinemann contrast discrimination model

    Science.gov (United States)

    Liu, Hong; Nodine, Calvin F.

    1996-07-01

    This paper presents a generalized image contrast enhancement technique, which equalizes the perceived brightness distribution based on the Heinemann contrast discrimination model. It is based on the mathematically proven existence of a unique solution to a nonlinear equation, and is formulated with easily tunable parameters. The model uses a two-step log-log representation of luminance contrast between targets and surround in a luminous background setting. The algorithm consists of two nonlinear gray scale mapping functions that have seven parameters, two of which are adjustable Heinemann constants. Another parameter is the background gray level. The remaining four parameters are nonlinear functions of the gray-level distribution of the given image, and can be uniquely determined once the previous three are set. Tests have been carried out to demonstrate the effectiveness of the algorithm for increasing the overall contrast of radiology images. The traditional histogram equalization can be reinterpreted as an image enhancement technique based on the knowledge of human contrast perception. In fact, it is a special case of the proposed algorithm.

  11. Generalized image contrast enhancement technique based on Heinemann contrast discrimination model

    Science.gov (United States)

    Liu, Hong; Nodine, Calvin F.

    1994-03-01

    This paper presents a generalized image contrast enhancement technique which equalizes perceived brightness based on the Heinemann contrast discrimination model. This is a modified algorithm which presents an improvement over the previous study by Mokrane in its mathematically proven existence of a unique solution and in its easily tunable parameterization. The model uses a log-log representation of contrast luminosity between targets and the surround in a fixed luminosity background setting. The algorithm consists of two nonlinear gray-scale mapping functions which have seven parameters, two of which are adjustable Heinemann constants. Another parameter is the background gray level. The remaining four parameters are nonlinear functions of gray scale distribution of the image, and can be uniquely determined once the previous three are given. Tests have been carried out to examine the effectiveness of the algorithm for increasing the overall contrast of images. It can be demonstrated that the generalized algorithm provides better contrast enhancement than histogram equalization. In fact, the histogram equalization technique is a special case of the proposed mapping.

  12. U-shape rotating anti-cathode compact X-ray generator: 20 times stronger than the commercially available X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Sakabe, N., E-mail: sakabe-dsb@sbsp.jp; Sakabe, K. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801 (Japan); Foundation for Advancement of International Science (FAIS), Kasuga 3-chome, Tsukuba, Ibaraki 305-0821 (Japan); Ohsawa, S.; Sakai, T.; Kobayakawa, H.; Sugimura, T.; Ikeda, M.; Tawada, M. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Watanabe, N.; Sasaki, K. [Nagoya University, Chikusa, Nagoya, Aichi 464-8603 (Japan); Wakatsuki, M. [National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8568 (Japan)

    2013-11-01

    stronger than that of the original commercially offered X-ray generator that we modified.

  13. Reorganization of a marine trophic network along an inshore-offshore gradient due to stronger pelagic-benthic coupling in coastal areas

    Science.gov (United States)

    Kopp, Dorothée; Lefebvre, Sébastien; Cachera, Marie; Villanueva, Maria Ching; Ernande, Bruno

    2015-01-01

    Recent theoretical considerations have highlighted the importance of the pelagic-benthic coupling in marine food webs. In continental shelf seas, it was hypothesized that the trophic network structure may change along an inshore-offshore gradient due to weakening of the pelagic-benthic coupling from coastal to offshore areas. We tested this assumption empirically using the eastern English Channel (EEC) as a case study. We sampled organisms from particulate organic matter to predatory fishes and used baseline-corrected carbon and nitrogen stable isotope ratios (δ13C and δ15N) to determine their trophic position. First, hierarchical clustering on δ13C and δ15N coupled to bootstrapping and estimates of the relative contribution of pelagic and benthic carbon sources to consumers' diet showed that, at mesoscale, the EEC food web forms a continuum of four trophic levels with trophic groups spread across a pelagic and a benthic trophic pathway. Second, based on the same methods, a discrete approach examined changes in the local food web structure across three depth strata in order to investigate the inshore-offshore gradient. It showed stronger pelagic-benthic coupling in shallow coastal areas mostly due to a reorganization of the upper consumers relative to the two trophic pathways, benthic carbon sources being available to pelagic consumers and, reciprocally, pelagic sources becoming accessible to benthic species. Third a continuous approach examined changes in the mean and variance of upper consumers' δ13C and δ15N with depth. It detected a significant decrease in δ13C variance and a significant increase in δ15N variance as depth increases. A theoretical two-source mixing model showed that an inshore-offshore decrease in the pelagic-benthic coupling was a sufficient condition to produce the δ13C variance pattern, thus supporting the conclusions of the discrete approach. These results suggest that environmental gradients such as the inshore-offshore one should

  14. Prolonged retainment of contrast media in renal tumours by oily X-ray contrast media

    International Nuclear Information System (INIS)

    Ryzkov, V.K.; Anisimov, V.N.

    1990-01-01

    In 194 patients with renal tumours an angiographic investigation with the oily X-ray contrast medium Iodolipol was carried out. A selective tropism of oily X-ray contrast media was found in the malignant zones only. The application of the preparation caused no complications. The oily X-ray contrast medium persisted in the tumours over several weeks or months. After embolization of the renal arteria a moderate size reduction of malign tumours in the first 10-14 d was seen. The ability of Iodolipol for a lasting retainment in malign tumour tissue allows a follow-up of the involution of the pathologic focus after arterial embolization of the tumour vessels. (author)

  15. Longitudinal multilevel models of the big-fish-little-pond effect on academic self-concept: counterbalancing contrast and reflected-glory effects in Hong Kong schools.

    Science.gov (United States)

    Marsh, H W; Kong, C K; Hau, K T

    2000-02-01

    Longitudinal multilevel path models (7,997 students, 44 high schools, 4 years) evaluated effects of school-average achievement and perceived school status on academic self-concept in Hong Kong, which has a collectivist culture with a highly achievement-segregated high school system. Consistent with a priori predictions based on the big-fish-little-pond effect (BFLPE), higher school-average achievements led to lower academic self-concepts (contrast effect), whereas higher perceived school status had a counterbalancing positive effect on self-concept (reflected-glory, assimilation effect). The negative BFLPE is the net effect of counterbalancing influences, stronger negative contrast effects, and weaker positive assimilation effects so that controlling perceived school status led to purer--and even more negative--contrast effects. Attending a school where school-average achievement is high simultaneously resulted in a more demanding basis of comparison for one's own accomplishments (the stronger negative contrast effect) and a source of pride (the weaker positive assimilation effect).

  16. Fast mutual-information-based contrast enhancement

    Science.gov (United States)

    Cao, Gang; Yu, Lifang; Tian, Huawei; Huang, Xianglin; Wang, Yongbin

    2017-07-01

    Recently, T. Celik proposed an effective image contrast enhancement (CE) method based on spatial mutual information and PageRank (SMIRANK). According to the state-of-the-art evaluation criteria, it achieves the best visual enhancement quality among existing global CE methods. However, SMIRANK runs much slower than the other counterparts, such as histogram equalization (HE) and adaptive gamma correction. Low computational complexity is also required for good CE algorithms. In this paper, we novelly propose a fast SMIRANK algorithm, called FastSMIRANK. It integrates both spatial and gray-level downsampling into the generation of pixel value mapping function. Moreover, the computation of rank vectors is speeded up by replacing PageRank with a simple yet efficient row-based operation of mutual information matrix. Extensive experimental results show that the proposed FastSMIRANK could accelerate the processing speed of SMIRANK by about 20 times, and is even faster than HE. Comparable enhancement quality is preserved simultaneously.

  17. Screened Poisson Equation for Image Contrast Enhancement

    Directory of Open Access Journals (Sweden)

    Jean-Michel Morel

    2014-03-01

    Full Text Available In this work we propose a discussion and detailed implementation of a very simple gradient domain method that tries to eliminate the effect of nonuniform illumination and at the same time preserves the images details. This model, which to the best of our knowledge has not been explored in spite of its simplicity, acts as a high pass filter. We show that with a single contrast parameter (which keeps the same value in most experiments, the model delivers state of the art results. They compare favorably to results obtained with more complex algorithms. Our algorithm is designed for all kinds of images, but with the special specification of making minimal image detail alteration thanks to a first order fidelity term, instead of the usual zero order term. Experiments on non-uniform medical images and on hazy images illustrate significant perception gain.

  18. Selective Contrast Adjustment by Poisson Equation

    Directory of Open Access Journals (Sweden)

    Ana-Belen Petro

    2013-09-01

    Full Text Available Poisson Image Editing is a new technique permitting to modify the gradient vector field of an image, and then to recover an image with a gradient approaching this modified gradient field. This amounts to solve a Poisson equation, an operation which can be efficiently performed by Fast Fourier Transform (FFT. This paper describes an algorithm applying this technique, with two different variants. The first variant enhances the contrast by increasing the gradient in the dark regions of the image. This method is well adapted to images with back light or strong shadows, and reveals details in the shadows. The second variant of the same Poisson technique enhances all small gradients in the image, thus also sometimes revealing details and texture.

  19. Contrast media in gall bladder diagnostics

    International Nuclear Information System (INIS)

    Schindler, G.; Frommhold, W.

    1982-01-01

    The justification of conventional X-ray diagnostic of bile ducts is repeatedly questioned by newer examination techniques like sonography and ERC. The indication for oral cholesgraphy is derived from its high-specifity of its statements for gall bladder diagnostic, that is as high as with sonography and does not depend on the experience of the investigator. The importance of the the void exposure is undoubted with correspondence of medicamentary litholysis for calcite identification. Furthermore, Choleocystic kineticals like Ceruletid let recognize better hyper plastic choleocysts like adenomyomatoses. The intravenous choleocyst-cholangiography posesses a clearly limited indication scheme even after introduction of sonography and ERC. The infusion method yields a better compatibility of the contrast medium with a simultaneous increased representation quality of the bile duct, that can be increased by a consequent application of the layer exposure technique. (orig.) [de

  20. CEST and PARACEST MR contrast agents

    International Nuclear Information System (INIS)

    Hancu, Ileana; Dixon, W. Thomas; Woods, Mark; Sherry, A. Dean; Vinogradov, Elena; Lenkinski, Robert E.

    2010-01-01

    In this review we describe the status of development for a new class of magnetic resonance (MR) contrast agents, based on chemical exchange saturation transfer (CEST). The mathematics and physics relevant to the description of the CEST effect in MR are presented in an appendix published in the online version only. We discuss the issues arising when translating in vitro results obtained with CEST agents to using these MR agents in in vivo model studies and in humans. Examples are given on how these agents are imaged in vivo. We summarize the status of development of these CEST agents, and speculate about the next steps that may be taken towards the demonstration of CEST MR imaging in clinical applications

  1. CONTRAST ENHANCED SPECTRAL MAMMOGRAPHY (CESM (REVIEW

    Directory of Open Access Journals (Sweden)

    N. I. Rozhkova

    2015-01-01

    Full Text Available The problem of early diagnosis of a breast cancer is extremely actual. Growth of incidence at women from 19 to 39 years increased for 34% over the last 10 years. It defines need of acceleration of development and deployment of the latest technologies of identification of the earliest symptoms of diseases. The x-ray mammography is the conducting method among of all radiological methods of diagnostics. Nevertheless a number of restrictions of method reduces its efficiency. The technologies increasing informational content of x-ray mammography – the leading method of screening – due to use of artificial contrasting and advantages of digital technologies are constantly developed. In this review it is described works, in which the authors having clinical experience of application of CESM – contrastenhanced spectral mammography on representative group of women. Positive sides and restrictions of new technology in comparison with mammography, ultrasonography and MRT are shown in this article.

  2. Gender Contrasts in Negotiation Impasse Rates

    Directory of Open Access Journals (Sweden)

    Michael J. Cotter

    2017-03-01

    Full Text Available This study contrasts the rate of impasse in genders in face-to-face negotiations for newly trained women and men. The empirical study analyzed negotiators’ negotiation impasse rates based on gender using a two-tailed t-test. The bargainers were involved in a series of ten high-stakes, zero-sum game negotiations. A total of 4,855 separate negotiations were examined. Overall, there were no statistically significant differences in the impasse rates of men and women The female rate of impasse was lower than the male rate of impasse, but without any significant differences, the results indicate that there are no gender differences in the abilities of negotiators to arrive at a deal.

  3. MRI contrast agents from molecules to particles

    CERN Document Server

    Laurent, Sophie; Stanicki, Dimitri; Boutry, Sébastien; Lipani, Estelle; Belaid, Sarah; Muller, Robert N; Vander Elst, Luce

    2017-01-01

    This book describes the multiple aspects of (i) preparation of the magnetic core, (ii) the stabilization with different coatings, (iii) the physico-chemical characterization and (iv) the vectorization to obtain specific nanosystems. Several bio-applications are also presented in this book. In the early days of Magnetic Resonance Imaging (MRI), paramagnetic ions were proposed as contrast agents to enhance the diagnostic quality of MR images. Since then, academic and industrial efforts have been devoted to the development of new and more efficient molecular, supramolecular and nanoparticular systems. Old concepts and theories, like paramagnetic relaxation, were revisited and exploited, leading to new scientific tracks. With their high relaxivity payload, the superparamagnetic nanoparticles are very appealing in the context of molecular imaging but challenges are still numerous: absence of toxicity, specificity, ability to cross the biological barriers, etc. .

  4. Process for preparation of MR contrast agents

    DEFF Research Database (Denmark)

    2002-01-01

    The present invention provides a process for the preparation of an MR contrast agent, said process comprising: i) obtaining a solution in a solvent of a hydrogenatable, unsaturated substrate compound and a catalyst for the hydrogenation of said substrate compound; ii) introducing said solution...... in droplet form into a chamber containing hydrogen gas (H2) enriched in para-hydrogen (p-1H2) and/or ortho-deuterium (o-2H2) whereby to hydrogenate said substrate to form a hydrogenated imaging agent; iii) optionally subjecting said hydrogenated imaging agent to a magnetic field having a field strength below...... earth's ambient field strength; iv) optionally dissolving said imaging agent in an aqueous medium; v) optionally separating said catalyst from the solution of said imaging agent in said aqueous medium; vi) optionally separating said solvent from the solution of said imaging agent in said aqueous medium...

  5. Contrastings views on bullying in Schools

    DEFF Research Database (Denmark)

    Hansen, Helle Rabøl

    Contrasting views on bullying in schools Which views on bullying influence teachers intervention strategies? This question is discussed  on the basis of the findings of my empirical study of that aspect of bullying that has to do with the position of the teacher (a quantitative survey...... of the teachers' staff room, observations, interviews and analysis of explicit ‘bullying-politics'). I found contradictions in teachers' definitions of the phenomenon of bullying, in how they describe causality and furthermore in how they would attempt to solve a specific and complicated bullying case....... The informants describe ‘bullying' in general terms that include group dynamic signs, when pressed for a causal explanation, or asked how they would handle a specific case. Most commonly, however, their focus is on the individual bully. In this, the teachers' positions seem to follow the commonplace conception...

  6. Contrast media and pain during peripheral arteriography

    International Nuclear Information System (INIS)

    Hagen, B.; Clauss, W.

    1982-01-01

    Some contrast media (CM) were for inducing pain and heat by an intraindividual comparison in 60 patients with occlusive peripheral arterial disease. A dolorimeter and calorimeter (graduated scales) were employed to register and differentiate the subjective sensations experienced by the patient, while objective reactions (peripheral motoric reactions, circulatory parameters) were recorded by the trialist at the same time. Ioxaglate, an ionic dimer, was distinctly superior to Ioglicinate, an ionic CM. However, the differences were less marked in the comparison with a Ioglicinate-Lidocaine-mixture. Emphasis is given to the fact osmolality is the most important parameter in the development of pain. Potential points at which the intraarterially administered local anaesthetic could attack are discussed. The clinical conclusions include consideration of the cost-effectivity ratios of the tested CM's and a discussion of whether or not modern stanards still justify general anaesthesia for peripheral angiography. (orig.)

  7. Patterns and contrasts in ophthalmic investigation.

    Science.gov (United States)

    Drasdo, N

    1988-01-01

    The Snellen test has been the most popular clinical measurement of spatial vision for over a century, but it does not fully express the visual ability of an individual. For more analytical purposes the information capacity of the visual system may be assessed by tests of contrast sensitivity and peripheral vision. The visual system selectively reduces the spatial information content of the visual field to avoid overloading the limited capacity for perception and decision making in the brain. The ways in which this reduction occurs and the processing of spatial information is of interest in many disciplines, and theoretical knowledge has been accelerated by the study of artificial intelligence. These processes may be investigated in human subjects by psychophysical and electrophysiological techniques. This provides additional information for diagnostic purposes and will form the basis of new systems of clinical investigation.

  8. Contrasts and synergies in different biofuel reports.

    Science.gov (United States)

    Michalopoulos, A; Landeweerd, L; Van der Werf-Kulichova, Z; Puylaert, P G B; Osseweijer, P

    2011-04-06

    The societal debate on biofuels is characterised by increased complexity. This can hinder the effective governance of the field. This paper attempts a quantitative bird's eye meta-analysis of this complexity by mapping different stakeholder perspectives and expected outcomes as seen in the secondary literature on biofuels, along the lines of the People-Planet-Profit framework. Our analysis illustrates the tension between stated and actual drivers of large scale biofuel development, especially for first generation biofuels. Although environmental (Planet) aspects have dominated the biofuel debate, their overall assessment is mostly negative with regard to first generation biofuels. By contrast, economic (Profit) aspects are the only ones that are assessed positively with regard to first generation biofuels. Furthermore, positive and negative assessments of biofuel development are strongly influenced by the differences in focus between different stakeholder clusters. Stakeholders who appear generally supportive to biofuel development (industry) focus relatively more on aspects that are generally assessed as positive (Profit). By contrast, non-supportive stakeholders (NGO's) tend to focus mainly on aspects that are generally assessed as negative (Planet). Moreover, our analysis of reference lists revealed few citations of primary scientific data, and also that intergovernmental organizations produce the most influential publications in the debate. The surprising lack of listed references to scientific (primary) data reveals a need to assess in which arena the transition of scientific data towards secondary publications takes place, and how one can measure its quality. This work should be understood as a first effort to take some control over a complex and contradictory number of publications, and to allow the effective governance of the field through the identification of areas of overlapping consensus and persisting controversy, without reverting to claims on

  9. Ocularity Feature Contrast Attracts Attention Exogenously

    Directory of Open Access Journals (Sweden)

    Li Zhaoping

    2018-02-01

    Full Text Available An eye-of-origin singleton, e.g., a bar shown to the left eye among many other bars shown to the right eye, can capture attention and gaze exogenously or reflexively, even when it appears identical to other visual input items in the scene and when the eye-of-origin feature is irrelevant to the observer’s task. Defining saliency as the strength of exogenous attraction to attention, we say that this eye-of-origin singleton, or its visual location, is salient. Defining the ocularity of a visual input item as the relative difference between its left-eye input and its right-eye input, this paper shows the general case that an ocularity singleton is also salient. For example, a binocular input item among monocular input items is salient, so is a left-eye-dominant input item (e.g., a bar with a higher input contrast to the left eye than to the right eye among right-eye-dominant items. Saliency by unique input ocularity is analogous to saliency by unique input colour (e.g., a red item among green ones, as colour is determined by the relative difference(s between visual inputs to different photoreceptor cones. Just as a smaller colour difference between a colour singleton and background items makes this singleton less salient, so does a smaller ocularity difference between an ocularity singleton and background items. While a salient colour difference is highly visible, a salient ocularity difference is often perceptually invisible in some cases and discouraging gaze shifts towards it in other cases, making its behavioural manifestation not as apparent. Saliency by ocularity contrast provides another support to the idea that the primary visual cortex creates a bottom-up saliency map to guide attention exogenously.

  10. Contrast optimization in multiphase arterial spin labeling; Otimizacao do contraste em ASL multi-fase

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Fernando F.; Paschoal, Andre M., E-mail: paiva@ifsc.usp.br [Universidade de Sao Paulo (CIERMag/USP), Sao Carlos, SP (Brazil). Instituto de Fisica; Foerster, Bernd U. [Philips Medical Systems LatAm, Sao Paulo, SP (Brazil); Tovar-Moll, Fernanda; Moll, Jorge [Instituto D' Or de Pesquisa e Ensino, Rio de Janeiro, RJ (Brazil)

    2013-08-15

    Multiphase ASL is an effective way to overcome the regional variation of the transit time that difficult the estimation of perfusion values. However, with conventional multiple phases ASL techniques, the ASL contrast at later phases is impaired due to repeated application of excitation pulses and longitudinal relaxation making it difficult to evaluate the tissue perfusion in regions where the transit time is longer. In the present study, we show an improvement of the acquisition scheme by exploring a modulation on the flip angle of the MR acquisition to keep the ASL contrast constant over multiple phases. (author)

  11. Contrasting water strategies of two Mediterranean shrubs of limited distribution: uncertain future under a drier climate.

    Science.gov (United States)

    Lázaro-Nogal, Ana; Forner, Alicia; Traveset, Anna; Valladares, Fernando

    2013-12-01

    Plants have evolved different strategies to cope with drought, involving alternative ecophysiologies and different levels of plasticity. These strategies are critical for species of limited distribution, which are especially vulnerable to the current rates of rapid environmental change. The aim of this study was to assess the water strategy of two species with limited distribution, Cneorum tricoccon L. and Rhamnus ludovici-salvatoris Chodat., and evaluate their interpopulation variability along an aridity gradient to estimate their vulnerability to a drier climate. We measured different ecophysiological traits influenced by drought--stomatal conductance, maximum photochemical efficiency of photosynthesis II, carbon isotope ratio and chlorophyll concentration--in two climatically contrasting years, before and during summer drought. Both species were vulnerable to drought at the aridity limit of the gradient, but showed contrasting water strategies: while C. tricoccon was consistent in its water conservation strategy across the aridity gradient, R. ludovici-salvatoris was not, displaying higher and more variable stomatal conductances and being able to increase water-use efficiency at the most xeric sites. Changes in length and intensity of drought events may favor one species' strategy to the detriment of the other: C. tricoccon is more vulnerable to chronic and prolonged droughts, whereas short but acute droughts might have a stronger effect on R. ludovici-salvatoris. In those communities where these two species coexist, such different strategies might lead to changes in community structure under climate change scenarios, with unknown cascade effects on ecosystem functioning.

  12. Contrasting burnout, turnover intention, control, value congruence and knowledge sharing between Baby Boomers and Generation X.

    Science.gov (United States)

    Leiter, Michael P; Jackson, Nicole J; Shaughnessy, Krystelle

    2009-01-01

    This paper examines the contrasting role of work values for nurses from two generations: Baby Boomers and Generation X. Differences among nurses regarding core values pertaining to their work has a potential to influence the quality of their work life. These differences may have implications for their vulnerability to job burnout. The analysis is based upon questionnaire surveys of nurses representing Generation X (n = 255) and Baby Boomers (n = 193) that contrasted their responses on job burnout, areas of work life, knowledge transfer and intention to quit. The analysis identified a greater person/organization value mismatch for Generation X nurses than for Baby Boomer nurses. Their greater value mismatch was associated with a greater susceptibility to burnout and a stronger intention to quit for Generation X nurses. The article notes the influence of Baby Boomer nurses in the structure of work and the application of new knowledge in health care work settings. Implications for recruitment and retention are discussed with a focus on knowledge transfer activities associated with distinct learning styles. Understanding value differences between generations will help nursing managers to develop more responsive work settings for nurses of all ages.

  13. Anaphylactic reaction to iodinated contrast media. Review the relevant loterature

    International Nuclear Information System (INIS)

    Kuwashima, Shigeko; Kitajima, Kazuhiro; Kohno, Tatsuo; Kaji, Yasushi; Takahashi, Tetuya; Seki, Masaya; Sakamoto, Tomoyuki

    2007-01-01

    Recently, iodinated contrast media are necessary for CT examinations and they occupy an important position in the radiological diagnosis. Nonionic contrast media significantly reduce the prevalence of all degree of adverse reaction to contrast media rather than ionic contrast media. So, generally, iodinated contrast media are safe and widely used, but adverse reaction after intravenous iodinated contrast media are not uncommon. Severe and potentially life-threatening reaction occur by using the iodinated contrast media practically. Patients at risk must be identified before the contrast media study, and all possible measures must be taken to deal effectively with spontaneous anaphylactic reactions. We report three cases of anaphylactic reactions by iodinated contrast media on CT. (author)

  14. L'analyse contrastive: histoire et situation actuelle (Contrastive Analysis: History and Current Situation).

    Science.gov (United States)

    Py, Bernard

    1984-01-01

    It is suggested that it is not between two languages that transfers and interference occur, but within the learner. The learner mediates and constructs this relationship according to acquisition operations, processes, strategies, and stages that contrastive analysis, despite its utility, can neither account for nor predict. (MSE)

  15. High Contrast Vacuum Nuller Testbed (VNT) Contrast, Performance and Null Control

    Science.gov (United States)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

    2012-01-01

    Herein we report on our Visible Nulling Coronagraph high-contrast result of 109 contrast averaged over a focal planeregion extending from 14 D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. TheVNC is a hybrid interferometriccoronagraphic approach for exoplanet science. It operates with high Lyot stopefficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential futureNASA flight telescopes. NASAGoddard Space Flight Center (GSFC) has a well-established effort to develop the VNCand its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and itsenabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry tounprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a W configurationto accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters.We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, criticaltechnologies and null sensing and control.

  16. Contrast-induced acute kidney injury: how much contrast is safe?

    LENUS (Irish Health Repository)

    Keaney, John J

    2013-02-14

    Iodinated contrast media (CM) are used in many investigations that a patient may undergo during the course of an in-patient stay. For the vast majority of patients, exposure to CM has no sequelae; however, in a small percentage, it can result in a worsening in renal function termed contrast-induced acute kidney injury (CI-AKI). CI-AKI is one of the leading causes of in-hospital renal dysfunction. It is associated with a significant increase in morbidity and mortality as well as an increased length of hospital stay and costs. Unfortunately, the results of extensive research into pharmacological inventions to prevent CI-AKI remain disappointing. In this article, we briefly outline the pathophysiological mechanisms by which iodinated CM may cause CI-AKI and discuss the evidence for reducing CI-AKI by limiting contrast volumes. In particular, we review the data surrounding the use of contrast volume to glomerular filtration rate ratios, which can be used by clinicians to effectively lower the incidence of CI-AKI in their patients.

  17. Variational contrast enhancement guided by global and local contrast measurements for single-image defogging

    Science.gov (United States)

    Zhou, Li; Bi, Du-Yan; He, Lin-Yuan

    2015-01-01

    The visibility of images captured in foggy conditions is impaired severely by a decrease in the contrasts of objects and veiling with a characteristic gray hue, which may limit the performance of visual applications out of doors. Contrast enhancement together with color restoration is a challenging mission for conventional fog-removal methods, as the degrading effect of fog is largely dependent on scene depth information. Nowadays, people change their minds by establishing a variational framework for contrast enhancement based on a physically based analytical model, unexpectedly resulting in color distortion, dark-patch distortion, or fuzzy features of local regions. Unlike previous work, our method treats an atmospheric veil as a scattering disturbance and formulates a foggy image as an energy functional minimization to estimate direct attenuation, originating from the work of image denoising. In addition to a global contrast measurement based on a total variation norm, an additional local measurement is designed in that optimal problem for the purpose of digging out more local details as well as suppressing dark-patch distortion. Moreover, we estimate the airlight precisely by maximization with a geometric constraint and a natural image prior in order to protect the faithfulness of the scene color. With the estimated direct attenuation and airlight, the fog-free image can be restored. Finally, our method is tested on several benchmark and realistic images evaluated by two assessment approaches. The experimental results imply that our proposed method works well compared with the state-of-the-art defogging methods.

  18. Moderate contrast in the evaluation of paintings is liked more but remembered less than high contrast

    NARCIS (Netherlands)

    K. Dijkstra (Katinka); van Dongen, N.N.N. (Noah N.N.)

    2017-01-01

    textabstractMany visual aspects of paintings, as well as exposure to art and cultural norms, contribute to the aesthetic evaluation of paintings. The current study looked at heightened visual contrast as an important factor in the appreciation of paintings. Participants evaluated abstract digitized

  19. High contrast vacuum nuller testbed (VNT) contrast, performance, and null control

    Science.gov (United States)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

    2012-09-01

    Herein we report on our Visible Nulling Coronagraph high-contrast result of 109 contrast averaged over a focal plane region extending from 1 - 4 λ/D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. The VNC is a hybrid interferometric/coronagraphic approach for exoplanet science. It operates with high Lyot stop efficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential future NASA flight telescopes. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop the VNC and its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and its enabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry to unprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a “W” configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, critical technologies and null sensing and control.

  20. Investigation of Pockels Cells Crystal Contrast Ratio Distribution

    Directory of Open Access Journals (Sweden)

    Giedrius Sinkevičius

    2017-07-01

    Full Text Available The BBO Pockel’s cell has been investigated. The investigation results of optimal operating area on the surface of the crystal dependent of intrinsic contrast ratio (ICR and voltage contrast ratio (VCR for Pockel’s cell are presented. The block diagram of Pockel’s cells contrast measurement stand and measurement methodology are introduced and discussed. The graphs of intrinsic contrast ratio distribution on crystal surface, contrast ratio with voltage dependency and voltage contrast ratio distribution on crystal surface with half-wave voltage are presented.

  1. Colorectal liver metastases: contrast agent diffusion coefficient for quantification of contrast enhancement heterogeneity at MR imaging.

    Science.gov (United States)

    Jia, Guang; O'Dell, Craig; Heverhagen, Johannes T; Yang, Xiangyu; Liang, Jiachao; Jacko, Richard V; Sammet, Steffen; Pellas, Theodore; Cole, Patricia; Knopp, Michael V

    2008-09-01

    To describe and determine the reproducibility of a simplified model to quantitatively measure heterogeneous intralesion contrast agent diffusion in colorectal liver metastases. This HIPAA-compliant retrospective study received institutional review board approval, and written informed consent was obtained from 14 patients (mean age, 61 years +/- 9 [standard deviation]; range, 41-78 years), including 10 men (mean age, 65 years +/- 8; range, 47-78 years) and four women (mean age, 54 years +/- 9; range, 41-59 years), with colorectal liver metastases. Magnetic resonance (MR) imaging was performed twice (first baseline MR image [B(1)] and second baseline MR image [B(2)]) in a single target lesion prior to therapy. Dynamic contrast material-enhanced MR imaging was performed by using a saturation-recovery fast gradient-echo sequence. A simplified contrast agent diffusion model was proposed, and a contrast agent diffusion coefficient (CDC) was calculated. The reproducibility of the CDC measurement was evaluated by using the Bland-Altman plot and a linear regression model. The mean CDC was 0.22 mm(2)/sec (range, 0.01-0.73 mm(2)/sec) on B(1) and 0.24 mm(2)/sec (range, 0.01-0.71 mm(2)/sec) on B(2), with an intraclass correlation coefficient of 0.91 (P < .0001). Bland-Altman plot showed good agreement, with a mean difference in measurement pairs of 0.017 mm(2)/sec +/- 0.096. The slope from the linear regression model was 0.89 (95% confidence interval: 0.63, 1.15) and the intercept was 0.01 (95% confidence interval: -0.08, 0.09). The CDC enables a quantitative description of contrast enhancement heterogeneity in lesions. Given the high reproducibility of the CDC metric, CDC appears promising for further qualification as an imaging biomarker of change measurement in response assessment. http://radiology.rsnajnls.org/cgi/content/full/248/3/901/DC1. RSNA, 2008

  2. NON-CONTRAST MAGNETIC RESONANCE UROGRAPHY

    Directory of Open Access Journals (Sweden)

    Arpita C

    2016-07-01

    Full Text Available BACKGROUND AND PURPOSE Magnetic Resonance (MR urography with its optimal contrast resolution and lack of ionizing radiation provides a comprehensive examination of the entire urinary tract noninvasively. MR urography is clinically useful in the evaluation of suspected urinary tract obstruction, haematuria, congenital anomalies, and surgically altered anatomy. It is particularly useful in cases of where there is contraindication of ionizing radiation and in paediatric and pregnant patients. The common MR urographic techniques are: Static-fluid MR urography and excretory MR urography. Static-fluid MR urography uses of heavily T2-weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (Cine MR urography to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenoses. Excretory MR urography is performed during the excretory phase of enhancement after the intravenous administration of gadolinium-based contrast material; thus, the patient must have sufficient renal function to allow the excretion. Static-fluid and excretory MR urography can be combined with conventional MR imaging for comprehensive evaluation of the urinary tract. The limitations are limited availability, high cost, relatively long examination time, low spatial resolution compared to IVU (Intravenous Urogram and CT Urography; sensitivity to motion (breathing and ureteral peristalsis inherent contraindications like patients with pacemakers, claustrophobia, and relative insensitivity for calcification and ureteric calculi. In this article, an attempt has been made to demonstrate the potential of static-fluid MRU to demonstrate a spectrum of urologic pathology involving the kidneys, ureters, and bladder while discussing the limitations. METHODS Thirty patients with urinary tract abnormalities were evaluated with MR urography performed between May 2014 to April 2016 using routine MR sequences and

  3. Dynamic contrast enhanced MRI in prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Alonzi, Roberto [Marie Curie Research Wing, Mount Vernon Cancer Centre, Rickmansworth Road, Northwood, Middlesex, HA6 2RN (United Kingdom)], E-mail: robertoalonzi@btinternet.com; Padhani, Anwar R. [Paul Strickland Scanner Centre, Mount Vernon Cancer Centre, Rickmansworth Road, Northwood, Middlesex, HA6 2RN (United Kingdom); Synarc Inc. 575 Market Street, San Francisco, CA 94105 (United States)], E-mail: anwar.padhani@paulstrickland-scannercentre.org.uk; Allen, Clare [Department of Imaging, University College Hospital, London, 235 Euston Road, NW1 2BU (United Kingdom)], E-mail: clare.allen@uclh.nhs.uk

    2007-09-15

    Angiogenesis is an integral part of benign prostatic hyperplasia (BPH), is associated with prostatic intraepithelial neoplasia (PIN) and is key to the growth and for metastasis of prostate cancer. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) using small molecular weight gadolinium chelates enables non-invasive imaging characterization of tissue vascularity. Depending on the technique used, data reflecting tissue perfusion, microvessel permeability surface area product, and extracellular leakage space can be obtained. Two dynamic MRI techniques (T{sub 2}*-weighted or susceptibility based and T{sub 1}-weighted or relaxivity enhanced methods) for prostate gland evaluations are discussed in this review with reference to biological basis of observations, data acquisition and analysis methods, technical limitations and validation. Established clinical roles of T{sub 1}-weighted imaging evaluations will be discussed including lesion detection and localisation, for tumour staging and for the detection of suspected tumour recurrence. Limitations include inadequate lesion characterisation particularly differentiating prostatitis from cancer, and in distinguishing between BPH and central gland tumours.

  4. Diffraction contrast imaging using virtual apertures

    International Nuclear Information System (INIS)

    Gammer, Christoph; Burak Ozdol, V.; Liebscher, Christian H.; Minor, Andrew M.

    2015-01-01

    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. - Highlights: • A dataset containing all structural information of a given position is recorded. • The dataset allows reconstruction of virtual diffraction patterns or images. • Specific virtual apertures are designed to image precipitates in a complex alloy. • Virtual diffraction patterns from arbitrarily small regions can be established. • Using STEM diffraction to record the dataset is more efficient than TEM dark-field

  5. Topical contrast-enhanced magnetic resonance dacryocystography

    International Nuclear Information System (INIS)

    Yoshikawa, Takeshi; Sugimura, Kazuro; Hirota, Shozo

    2000-01-01

    The purpose of this study was to evaluate the usefulness of magnetic resonance dacryocystography (MRD) with topical administration of normal saline solution and diluted Gd-DTPA solution for the assessment of lacrimal outflow disorders. Two T2-weighted sequences and two T1-weighted sequences were evaluated in this study. The 1:100 diluted Gd solution was prepared by diluting Gd-DTPA (Magnevist) with normal saline solution. A phantom study using tube phantoms of various diameters filled with normal saline solution and 1:100 diluted Gd solution was performed. A preliminary study was performed in ten normal volunteers Eighteen patients with lacrimal outflow disorders underwent clinical MRD, and 14 also underwent conventional dacryocystography (CDG). MRD images were evaluated and compared with clinical symptoms and CDG images. In all sequences, MRD could visualize the full length of 0.7 to 1.7 mm diameter tube phantoms and could show all of the normal lacrimal sacs and nasolacrimal ducts. In the clinical study, MRD findings were compatible with the symptoms in 14 patients but were not compatible with CDG findings in half of the cases. Topical contrast-enhanced MRD provided a simple, non-invasive means of obtaining detailed morphological and functional information on the lacrimal drainage apparatus. (author)

  6. Monitoring stem cells in phase contrast imaging

    Science.gov (United States)

    Lam, K. P.; Dempsey, K. P.; Collins, D. J.; Richardson, J. B.

    2016-04-01

    Understanding the mechanisms behind the proliferation of Mesenchymal Stem cells (MSCs) can offer a greater insight into the behaviour of these cells throughout their life cycles. Traditional methods of determining the rate of MSC differentiation rely on population based studies over an extended time period. However, such methods can be inadequate as they are unable to track cells as they interact; for example, in autologous cell therapies for osteoarthritis, the development of biological assays that could predict in vivo functional activity and biological action are particularly challenging. Here further research is required to determine non-histochemical biomarkers which provide correlations between cell survival and predictive functional outcome. This paper proposes using a (previously developed) advanced texture-based analysis algorithm to facilitate in vitro cells tracking using time-lapsed microscopy. The technique was adopted to monitor stem cells in the context of unlabelled, phase contrast imaging, with the goal of examining the cell to cell interactions in both monoculture and co-culture systems. The results obtained are analysed using established exploratory procedures developed for time series data and compared with the typical fluorescent-based approach of cell labelling. A review of the progress and the lessons learned are also presented.

  7. Smart Contrast Agents for Magnetic Resonance Imaging.

    Science.gov (United States)

    Bonnet, Célia S; Tóth, Éva

    2016-01-01

    By visualizing bioactive molecules or biological parameters in vivo, molecular imaging is searching for information at the molecular level in living organisms. In addition to contributing to earlier and more personalized diagnosis in medicine, it also helps understand and rationalize the molecular factors underlying physiological and pathological processes. In magnetic resonance imaging (MRI), complexes of paramagnetic metal ions, mostly lanthanides, are commonly used to enhance the intrinsic image contrast. They rely either on the relaxation effect of these metal chelates (T(1) agents), or on the phenomenon of paramagnetic chemical exchange saturation transfer (PARACEST agents). In both cases, responsive molecular magnetic resonance imaging probes can be designed to report on various biomarkers of biological interest. In this context, we review recent work in the literature and from our group on responsive T(1) and PARACEST MRI agents for the detection of biogenic metal ions (such as calcium or zinc), enzymatic activities, or neurotransmitter release. These examples illustrate the general strategies that can be applied to create molecular imaging agents with an MRI detectable response to biologically relevant parameters.

  8. Simultaneous brightness contrast of foraging Papilio butterflies

    Science.gov (United States)

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-01-01

    This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast. PMID:22179808

  9. Gadolinium-conjugated PLA-PEG nanoparticles as liver targeted molecular MRI contrast agent.

    Science.gov (United States)

    Chen, Zhijin; Yu, Dexin; Liu, Chunxi; Yang, Xiaoyan; Zhang, Na; Ma, Chunhong; Song, Jibin; Lu, Zaijun

    2011-09-01

    A nanoparticle magnetic resonance imaging (MRI) contrast agent targeted to liver was developed by conjugation of gadolinium (Gd) chelate groups onto the biocompatible poly(l-lactide)-block-poly (ethylene glycol) (PLA-PEG) nanoparticles. PLA-PEG conjugated with diethylenetriaminopentaacetic acid (DTPA) was used to formulate PLA-PEG-DTPA nanoparticles by solvent diffusion method, and then Gd was loaded onto the nanoparticles by chelated with the unfolding DTPA on the surface of the PLA-PEG-DTPA nanoparticles. The mean size of the nanoparticles was 265.9 ± 6.7 nm. The relaxivity of the Gd-labeled nanoparticles was measured, and the distribution in vivo was evaluated in rats. Compared with conventional contrast agent (Magnevist), the Gd-labeled PLA-PEG nanoparticles showed significant enhancement both on liver targeting ability and imaging signal intensity. The T(1) and T(2) relaxivities per [Gd] of the Gd-labeled nanoparticles was 18.865 mM(-1) s(-1) and 24.863 mM(-1) s(-1) at 3 T, respectively. In addition, the signal intensity in vivo was stronger comparing with the Gd-DTPA and the T(1) weight time was lasting for 4.5 h. The liver targeting efficiency of the Gd-labeled PLA-PEG nanoparticles in rats was 14.57 comparing with Magnevist injection. Therefore, the Gd-labeled nanoparticles showed the potential as targeting molecular MRI contrast agent for further clinical utilization.

  10. Improve identification of details in double-contrast examination of the stomach by means of a new contrast medium mixture

    International Nuclear Information System (INIS)

    Tenner, R.

    1984-01-01

    In a contrast medium study, 100 patients were employed for a comparison between the contrast medium Mikropaque liquid and a mixture of Mikropaque HD and Mikropaque liquid in double-contrast examination of the stomach. The special feature of this method was that one and the same stomach was examined in each case with both contrast media. The new contrast media mixture with Mikropaque HD represents a step forward; the contrast could be enhanced in 80% of the cases, and the finely contoured relief became visible in two-thirds of the cases, compared with one-third of the examined patients before this method was introduced. (orig.) [de

  11. Enhancing contrast of magnetic resonance imaging in patients with ...

    African Journals Online (AJOL)

    DTPA), a recent magnetic resonance imaging (MRI) contrast agent, in hepatobiliary system of patients with liver cirrhosis. Methods: Liver cirrhosis patients that underwent contrast MRI examination at Renai Hospital, Taipei City, Taiwan were ...

  12. Method and apparatus to characterize ultrasonically reflective contrast agents

    Science.gov (United States)

    Pretlow, Robert A., III (Inventor)

    1993-01-01

    A method and apparatus for characterizing the time and frequency response of an ultrasonically reflective contrast agent is disclosed. An ultrasonically reflective contrast agent is injected, under constant pressure, into a fluid flowing through a pump flow circuit. The fluid and the ultrasonically reflective contrast agent are uniformly mixed in a mixing chamber, and the uniform mixture is passed through a contrast agent chamber. The contrast agent chamber is acoustically and axially interposed between an ultrasonic transducer chamber and an acoustic isolation chamber. A pulse of ultrasonic energy is transmitted into the contrast agent chamber from the ultrasonic transducer chamber. An echo waveform is received from the ultrasonically reflective contrast agent, and it is analyzed to determine the time and frequency response of the ultrasonically reflective contrast agent.

  13. Positive behavioral contrast across food and alcohol reinforcers.

    OpenAIRE

    McSweeney, F K; Melville, C L; Higa, J

    1988-01-01

    The present study examined behavioral contrast during concurrent and multiple schedules that provided food and alcohol reinforcers. Concurrent-schedule contrast occurred in the responding reinforced by food when alcohol reinforcers were removed. It also occurred in the responding reinforced by alcohol when food was removed. Multiple-schedule contrast appeared for food when alcohol reinforcers were removed, but not for alcohol when food was removed. These results show that behavioral contrast ...

  14. Contrast characteristics of barium preparations and the timing of exposure

    OpenAIRE

    渋谷, 光一; 中桐, 義忠; 東, 義晴; 杉田, 勝彦; 小橋, 高郎; 大倉, 保彦; 丹谷, 延義; 三上, 泰隆; 平木, 祥夫

    1995-01-01

    We studied the relationship between the contrast characteristics of barium suspension and timing of exposure. We poured several kinds of barium preparations on the phantom manufactured by ourselves, and took X-ray pictures continuously by a DSA system. We analyzed each of the characteris-tics of the contrast. The time which was reguired for the contrast to reach the peak (Contrast Peak Time ; CPT) was unrelated with the kind of barium preparations used. It depended on the viscosity of the con...

  15. Contrasting Specific English Corpora: Language Variation

    Directory of Open Access Journals (Sweden)

    María Luisa Carrió Pastor

    2009-12-01

    Full Text Available The scientific community has traditionally considered technical English as neutral and objective, able to transmit ideas and research in simple sentences and specialized vocabulary. Nevertheless, global communication and intense information delivery have produced a range of different ways of knowledge transmission. Although technical English is considered an objective way to transmit science, writers of academic papers use some words or structures with different frequency in the same genre. As a consequence of this, contrastive studies about the use of second languages have been increasingly attracting scholarly attention. In this research, we evidence that variation in language production is a reality and can be proved contrasting corpora written by native writers of English and by non-native writers of English. The objectives of this paper are first to detect language variation in a technical English corpus; second, to demonstrate that this finding evidences the parts of the sentence that are more sensitive to variation; finally, it also evidences the non-standardisation of technical English. In order to fulfil these objectives, we analysed a corpus of fifty scientific articles written by native speakers of English and fifty scientific articles written by non-native speakers of English. The occurrences were classified and counted in order to detect the most common variations. Further analysis indicated that the variations were caused by mother tongue interference in virtually all cases, although meaning was only very rarely obscured. These findings suggest that the use of certain patterns and expressions originating from L1 interference should be considered as correct as standard English.La comunidad científica considera al inglés técnico como un tipo de lenguaje neutral y objetivo, capaz de transmitir ideas y hallazgos en frases simples y vocabulario reconocido por los especialistas de ese campo. Sin embargo, la comunicación global y el

  16. Contrast to Noise Ratio and Contrast Detail Analysis in Mammography:A Monte Carlo Study

    International Nuclear Information System (INIS)

    Metaxas, V; Delis, H; Panayiotakis, G; Kalogeropoulou, C; Zampakis, P

    2015-01-01

    The mammographic spectrum is one of the major factors affecting image quality in mammography. In this study, a Monte Carlo (MC) simulation model was used to evaluate image quality characteristics of various mammographic spectra. The anode/filter combinations evaluated, were those traditionally used in mammography, for tube voltages between 26 and 30 kVp. The imaging performance was investigated in terms of Contrast to Noise Ratio (CNR) and Contrast Detail (CD) analysis, by involving human observers, utilizing a mathematical CD phantom. Soft spectra provided the best characteristics in terms of both CNR and CD scores, while tube voltage had a limited effect. W-anode spectra filtered with k-edge filters demonstrated an improved performance, that sometimes was better compared to softer x-ray spectra, produced by Mo or Rh anode. Regarding the filter material, k-edge filters showed superior performance compared to Al filters. (paper)

  17. Contrast enhanced ultrasound of splenic lymphoma involvement

    International Nuclear Information System (INIS)

    Goerg, Christian; Faoro, Charis; Bert, Tillmann; Tebbe, Johannes; Neesse, Albrecht; Wilhelm, Christian

    2011-01-01

    Objective: The aim of this study was to compare the value of contrast-enhanced ultrasonography (CEUS) with standard B-mode ultrasound (US) for diagnosis of splenic lymphoma involvement. Methods: From 04/2005 to 10/2008 n = 250 lymphoma patients were investigated by standard B-mode US. A homogeneous splenic echotexture was found in 199 patients (79%). To clarify the benefit of CEUS in this group a pilot series was performed with 16 of the 199 lymphoma patients. All patients with an abnormal splenic echotexture on standard B-Mode US (n = 51) including focal hypoechoic splenic lesions (n = 41) and an inhomogeneous splenic texture (n = 10) were studied by CEUS. CEUS data were retrospectively evaluated. The diagnoses included indolent lymphoma (n = 27), aggressive lymphoma (n = 14), and Hodgkin's disease (n = 10). Number and size of lesions were determined by B-mode US and CEUS. The visualisation of splenic lymphoma involvement by CEUS in comparison to B-mode US was classified as worse, equal, or better. Results: All patients with a homogeneous spleen on B-mode US (n = 16) had no visible focal lesions on CEUS. Study patients with focal lesions (n = 41) had a hypoechoic (n = 22) or isoechoic (n = 19) enhancement during the arterial phase, and a hypoechoic enhancement during the parenchymal phase (n = 41). The visualisation of focal splenic lymphoma was equal (n = 32), better (n = 6), or worse (n = 3). In all study patients with an inhomogeneous spleen on B-mode US (n = 10) no focal lesions were found by CEUS and the value of CEUS therefore was classified as worse. Conclusion: CEUS has no clear advantage for diagnosis of splenic lymphoma involvement.

  18. Contrast enhanced ultrasound of splenic lymphoma involvement

    Energy Technology Data Exchange (ETDEWEB)

    Goerg, Christian, E-mail: goergc@med.uni-marburg.de [Medizinische Universitaetsklinik, Baldingerstrasse, 35033 Marburg/Lahn (Germany); Faoro, Charis [Medizinische Universitaetsklinik, Baldingerstrasse, 35033 Marburg/Lahn (Germany); Bert, Tillmann [Zentralklinik Bad Berka GmbH, Robert-Koch-Allee 9, 99437 Bad Berka (Germany); Tebbe, Johannes [Klinikum Lippe-Detmold, Roentgenstrasse 18, 32756 Detmold (Germany); Neesse, Albrecht; Wilhelm, Christian [Medizinische Universitaetsklinik, Baldingerstrasse, 35033 Marburg/Lahn (Germany)

    2011-11-15

    Objective: The aim of this study was to compare the value of contrast-enhanced ultrasonography (CEUS) with standard B-mode ultrasound (US) for diagnosis of splenic lymphoma involvement. Methods: From 04/2005 to 10/2008 n = 250 lymphoma patients were investigated by standard B-mode US. A homogeneous splenic echotexture was found in 199 patients (79%). To clarify the benefit of CEUS in this group a pilot series was performed with 16 of the 199 lymphoma patients. All patients with an abnormal splenic echotexture on standard B-Mode US (n = 51) including focal hypoechoic splenic lesions (n = 41) and an inhomogeneous splenic texture (n = 10) were studied by CEUS. CEUS data were retrospectively evaluated. The diagnoses included indolent lymphoma (n = 27), aggressive lymphoma (n = 14), and Hodgkin's disease (n = 10). Number and size of lesions were determined by B-mode US and CEUS. The visualisation of splenic lymphoma involvement by CEUS in comparison to B-mode US was classified as worse, equal, or better. Results: All patients with a homogeneous spleen on B-mode US (n = 16) had no visible focal lesions on CEUS. Study patients with focal lesions (n = 41) had a hypoechoic (n = 22) or isoechoic (n = 19) enhancement during the arterial phase, and a hypoechoic enhancement during the parenchymal phase (n = 41). The visualisation of focal splenic lymphoma was equal (n = 32), better (n = 6), or worse (n = 3). In all study patients with an inhomogeneous spleen on B-mode US (n = 10) no focal lesions were found by CEUS and the value of CEUS therefore was classified as worse. Conclusion: CEUS has no clear advantage for diagnosis of splenic lymphoma involvement.

  19. Females engage in stronger relationships: positive and negative effects of shrubs are more intense for Poa ligularis females than for males.

    Science.gov (United States)

    Graff, Pamela; Aguiar, Martin R; Almeida, Rocio J

    2018-05-22

    Dioecious plants are of particular concern in view of global environmental changes because reproductive females are more sensitive to abiotic stresses, thus compromising population viability. Positive interactions with other plants may counteract the direct effects of any abiotic environmental stress, allowing them to thrive and maintain a viable population in suboptimal habitats, although this process has not been tested for dioecious species. Furthermore, almost no data are available on the outcome of such species interactions and their link with local spatial patterns and sex ratios. We set up a field experiment with Poa ligularis, a dioecious native grass from the arid grasslands of South America. We studied the interaction of male and female plants with cushion shrubs of contrasting ecological strategies. We experimentally limited direct shrub-grass competition for soil moisture and transplanted plants to evaluate the amelioration of abiotic stress by shrub canopies (i.e. sun and wind) on grasses. We also studied the distribution of naturally established female and male plants to infer process-pattern relationships. Positive canopy effects as well as negative below-ground effects were more intense for females than for males. Deep-rooted Mulinum spinosum shrubs strongly facilitated survival, growth and reproduction of P. ligularis females. Naturally established female plants tended to distribute more closely to Mulinum than co-occurring males. Female growth suffered intensive negative root competition from the shallow-rooted Senecio filaginoides shrub. Interactions with other plants may reduce or enhance the effect of abiotic stresses on the seemingly maladapted sex to arid environments. We found that these biased interactions are evident in the current organization of sexes in the field, confirming our experimental findings. Therefore, indirect effects of climate change on population sex ratios may be expected if benefactor species abundances are

  20. Patient safety and adverse events in contrast medium examinations

    International Nuclear Information System (INIS)

    Enge, I.; Edgren, J.

    1989-01-01

    This volume contains six contributions dealing with the properties, safety and economic aspects (lower risks but higher costs of new low-osmonality contrast media compared to the older high-osmonality, ionic ones) of contrast media used in radiology, and risks involved in procedures for administering of radiologic contrast media. (H.W.). refs.; figs.; tabs

  1. Non-ionic contrast media: are they obligatory?

    International Nuclear Information System (INIS)

    Halva, S.R.

    1993-01-01

    Author presents recommendations for nonionic contrast media application. They are more expensive but less toxic than ionic ones. In order to avoid side effects in many radiological examinations (phlebography, arteriography, coronarography, ventriculography) one should use nonionic contrast media. Another reason for application of nonionic contrast agents is young age of patient or his state of health

  2. Iodine-based contrast media, multiple myeloma and monoclonal gammopathies

    DEFF Research Database (Denmark)

    Stacul, Fulvio; Bertolotto, Michele; Thomsen, Henrik S

    2018-01-01

    OBJECTIVES: Many radiologists and clinicians still consider multiple myeloma (MM) and monoclonal gammopathies (MG) a contraindication for using iodine-based contrast media. The ESUR Contrast Media Safety Committee performed a systematic review of the incidence of post-contrast acute kidney injury...

  3. The effect of defocus on edge contrast sensitivity

    NARCIS (Netherlands)

    Jansonius, NM; Kooijman, AC

    The effect of optical blur (defocus) on edge contrast sensitivity was studied. Edge contrast sensitivity detoriates with fairly small amounts of blur (similar to 0.5 D) and is roughly reduced by half for each dioptre of blur. The effect of blur on edge contrast sensitivity equals the effect of blur

  4. Contrast as denial in multi-dimensional semantics

    NARCIS (Netherlands)

    Spenader, Jennifer; Maier, Emar

    We argue that contrastive statements have the same underlying semantics and affect the context in the same way as denials. We substantiate this claim by giving a unified account of the two phenomena that treats contrast as a subtype of denial. We argue that earlier work on contrast-denial obscured

  5. Contrast-enhanced spectral mammography (CESM) and contrast enhanced MRI (CEMRI): Patient preferences and tolerance.

    Science.gov (United States)

    Hobbs, Max M; Taylor, Donna B; Buzynski, Sebastian; Peake, Rachel E

    2015-06-01

    Contrast-enhanced spectral mammography (CESM) may have similar diagnostic performance to Contrast-enhanced MRI (CEMRI) in the diagnosis and staging of breast cancer. To date, research has focused exclusively on diagnostic performance when comparing these two techniques. Patient experience is also an important factor when comparing and deciding on which of these modalities is preferable. The aim of this study is to compare patient experience of CESM against CEMRI during preoperative breast cancer staging. Forty-nine participants who underwent both CESM and CEMRI, as part of a larger trial, completed a Likert questionnaire about their preference for each modality according to the following criteria: comfort of breast compression, comfort of intravenous (IV) contrast injection, anxiety and overall preference. Participants also reported reasons for preferring one modality to the other. Quantitative data were analysed using a Wilcoxon sign-rank test and chi-squared test. Qualitative data are reported descriptively. A significantly higher overall preference towards CESM was demonstrated (n = 49, P < 0.001), with faster procedure time, greater comfort and lower noise level cited as the commonest reasons. Participants also reported significantly lower rates of anxiety during CESM compared with CEMRI (n = 36, P = 0.009). A significantly higher rate of comfort was reported during CEMRI for measures of breast compression (n = 49, P = 0.001) and the sensation of IV contrast injection (n = 49, P = 0.003). Our data suggest that overall, patients prefer the experience of CESM to CEMRI, adding support for the role of CESM as a possible alternative to CEMRI for breast cancer staging. © 2015 The Royal Australian and New Zealand College of Radiologists.

  6. Contrast-enhanced spectral mammography (CESM) and contrast enhanced MRI (CEMRI): Patient preferences and tolerance

    International Nuclear Information System (INIS)

    Hobbs, Max; Buzynski, Sebastian; Taylor, Donna B.; Peake, Rachel E.

    2015-01-01

    Contrast-enhanced spectral mammography (CESM) may have similar diagnostic performance to Contrast-enhanced MRI (CEMRI) in the diagnosis and staging of breast cancer. To date, research has focused exclusively on diagnostic performance when comparing these two techniques. Patient experience is also an important factor when comparing and deciding on which of these modalities is preferable. The aim of this study is to compare patient experience of CESM against CEMRI during preoperative breast cancer staging. Forty-nine participants who underwent both CESM and CEMRI, as part of a larger trial, completed a Likert questionnaire about their preference for each modality according to the following criteria: comfort of breast compression, comfort of intravenous (IV) contrast injection, anxiety and overall preference. Participants also reported reasons for preferring one modality to the other. Quantitative data were analysed using a Wilcoxon sign-rank test and chi-squared test. Qualitative data are reported descriptively. A significantly higher overall preference towards CESM was demonstrated (n = 49, P < 0.001), with faster procedure time, greater comfort and lower noise level cited as the commonest reasons. Participants also reported significantly lower rates of anxiety during CESM compared with CEMRI (n = 36, P = 0.009). A significantly higher rate of comfort was reported during CEMRI for measures of breast compression (n = 49, P = 0.001) and the sensation of IV contrast injection (n = 49, P = 0.003). Our data suggest that overall, patients prefer the experience of CESM to CEMRI, adding support for the role of CESM as a possible alternative to CEMRI for breast cancer staging.

  7. Computer-aided diagnosis in contrast-enhanced CT colonography: an approach based on contrast

    International Nuclear Information System (INIS)

    Luboldt, Wolfgang; Kroll, Manuela; Vogl, Thomas J.; Mann, Carolin; Vonthein, Reinhard; Stueker, Dietmar; Luz, Oliver; Claussen, Claus D.; Tryon, Cathy L.

    2002-01-01

    Automation in colorectal mass detection is achieved as soon as the voxels representing colorectal masses can be automatically segmented. We tested the Hounsfield (HU) value in intensely contrast enhanced high-resolution CT colonography for automated segmentation of colorectal masses in 18 patients with 35 polyps (28<10 mm, 7 ≥10 mm) and 7 carcinomas. Mean HU values of the colonic wall and masses were determined to deduce a gradient threshold for a segmentation process, which encodes the voxels bordering the colonic lumen with a colour ranging in intensity from 0 to 100% according to the selected gradient threshold range in the volume rendering. The results of the automated segmentation process were superimposed on a virtual double contrast and endoscopic display and validated through correlation with morphology. Mean HU values and their standard deviations for the colonic wall, polyps <10 mm, polyps ≥10 mm and carcinomas were 63±24, 154±38, 116±41 and 108±29 HU, respectively. A gradient threshold ranging from 90 to 160 HU resulted in colour pools in 6 of 7 of polyps ≥10 mm, and 6 of 7 carcinomas that were significant enough to prospectively guide the reader's attention to these masses. Due to the superposition of ''false-positive'' voxels in the projection view, the virtual endoscopic perspective was superior to the virtual double contrast display for controlling the segmentation results. The HU value is promising for automated segmentation of colorectal masses but needs to be combined with morphological parameters to render automated colorectal mass detection more accurate. Further refinements of the method with subsequent analysis of its accuracy, as well as analogue studies with contrast-enhanced MRI, appear warranted. More information at http://www.multiorganscreening.org (orig.)

  8. Chromatic and achromatic monocular deprivation produce separable changes of eye dominance in adults.

    Science.gov (United States)

    Zhou, Jiawei; Reynaud, Alexandre; Kim, Yeon Jin; Mullen, Kathy T; Hess, Robert F

    2017-11-29

    Temporarily depriving one eye of its input, in whole or in part, results in a transient shift in eye dominance in human adults, with the patched eye becoming stronger and the unpatched eye weaker. However, little is known about the role of colour contrast in these behavioural changes. Here, we first show that the changes in eye dominance and contrast sensitivity induced by monocular eye patching affect colour and achromatic contrast sensitivity equally. We next use dichoptic movies, customized and filtered to stimulate the two eyes differentially. We show that a strong imbalance in achromatic contrast between the eyes, with no colour content, also produces similar, unselective shifts in eye dominance for both colour and achromatic contrast sensitivity. Interestingly, if this achromatic imbalance is paired with similar colour contrast in both eyes, the shift in eye dominance is selective, affecting achromatic but not chromatic contrast sensitivity and revealing a dissociation in eye dominance for colour and achromatic image content. On the other hand, a strong imbalance in chromatic contrast between the eyes, with no achromatic content, produces small, unselective changes in eye dominance, but if paired with similar achromatic contrast in both eyes, no changes occur. We conclude that perceptual changes in eye dominance are strongly driven by interocular imbalances in achromatic contrast, with colour contrast having a significant counter balancing effect. In the short term, eyes can have different dominances for achromatic and chromatic contrast, suggesting separate pathways at the site of these neuroplastic changes. © 2017 The Author(s).

  9. Effect of static scatterers in laser speckle contrast imaging: an experimental study on correlation and contrast

    Science.gov (United States)

    Vaz, Pedro G.; Humeau-Heurtier, Anne; Figueiras, Edite; Correia, Carlos; Cardoso, João

    2018-01-01

    Laser speckle contrast imaging (LSCI) is a non-invasive microvascular blood flow assessment technique with good temporal and spatial resolution. Most LSCI systems, including commercial devices, can perform only qualitative blood flow evaluation, which is a major limitation of this technique. There are several factors that prevent the utilization of LSCI as a quantitative technique. Among these factors, we can highlight the effect of static scatterers. The goal of this work was to study the influence of differences in static and dynamic scatterer concentration on laser speckle correlation and contrast. In order to achieve this, a laser speckle prototype was developed and tested using an optical phantom with various concentrations of static and dynamic scatterers. It was found that the laser speckle correlation could be used to estimate the relative concentration of static/dynamic scatterers within a sample. Moreover, the speckle correlation proved to be independent of the dynamic scatterer velocity, which is a fundamental characteristic to be used in contrast correction.

  10. Contrast between hypervascularized liver lesions and hepatic parenchyma. Early dynamic PET versus contrast-enhanced CT

    International Nuclear Information System (INIS)

    Freesmeyer, M.; Winkens, T.; Schierz, J.-H.

    2014-01-01

    To detect hypervascularized liver lesions, early dynamic (ED) 18 F-FDG PET may be an alternative when contrast-enhanced (CE) imaging is infeasible. This retrospective pilot analysis compared contrast between such lesions and liver parenchyma, an important objective image quality variable, in ED PET versus CE CT. Twenty-eight hypervascularized liver lesions detected by CE CT [21 (75%) hepatocellular carcinomas; mean (range) diameter 4.9 ± 3.5 (1-14) cm] in 20 patients were scanned with ED PET. Using regions of interest, maximum and mean lesional and parenchymal signals at baseline, arterial and venous phases were calculated for ED PET and CE CT. Lesional/parenchymal signal ratio was significantly higher (P < 0.005) with ED PET versus CE CT at the arterial phase and similar between the methods at the venous phase. In liver imaging, ED PET generates greater lesional-parenchymal contrast during the arterial phase than does CE CT; these observations should be formally, prospectively evaluated. (author)

  11. Comparison of excretory urographic contrast effects of dimeric and monomeric non-ionic iodinated contrast media in dogs

    International Nuclear Information System (INIS)

    Kishimoto, M.; Yamada, K.; Watanabe, A.; Miyamoto, K.; Iwasaki, T.; Miyake, Y.

    2007-01-01

    In excretory urography, the osmolarity of contrast media has rarely been treated as important in veterinary medicine. In this study, the contrast effect of two contrast media (monomeric iohexol and dimeric iodixanol) in the renal cortex and aorta were compared using computed tomography (CT). Five beagle dogs were used and the study employed a cross-over method for each contrast media. The results showed that there was no difference between the media in the aorta, but iodixanol showed higher CT value and a longer contrast effect than iohexol in the renal cortex, in spite of having the same iodine dosage. It is believed that iodixanol, with its low osmolarity, is diluted less by osmotic diuresis than monomeric iohexol. It is important to consider the osmolarity of the contrast media when evaluating the contrast effect, and it is essential to use the same contrast media for each examination, or the renal excretory speed will be under/overestimated

  12. Gadolinium-based contrast agents in pediatric magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gale, Eric M.; Caravan, Peter [Massachusetts General Hospital, Harvard Medical School, Department of Radiology, The Martinos Center for Biomedical Imaging, Boston, MA (United States); Rao, Anil G. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); McDonald, Robert J. [College of Medicine, Mayo Clinic, Department of Radiology, Rochester, MN (United States); Winfeld, Matthew [University of Pennsylvania Perelman School of Medicine, Philadelphia, PA (United States); Fleck, Robert J. [Cincinnati Children' s Hospital Medical Center, Department of Pediatric Radiology, Cincinnati, OH (United States); Gee, Michael S. [MassGeneral Hospital for Children, Harvard Medical School, Division of Pediatric Imaging, Department of Radiology, Boston, MA (United States)

    2017-05-15

    Gadolinium-based contrast agents can increase the accuracy and expediency of an MRI examination. However the benefits of a contrast-enhanced scan must be carefully weighed against the well-documented risks associated with administration of exogenous contrast media. The purpose of this review is to discuss commercially available gadolinium-based contrast agents (GBCAs) in the context of pediatric radiology. We discuss the chemistry, regulatory status, safety and clinical applications, with particular emphasis on imaging of the blood vessels, heart, hepatobiliary tree and central nervous system. We also discuss non-GBCA MRI contrast agents that are less frequently used or not commercially available. (orig.)

  13. The use of new contrast media agents in radiology

    International Nuclear Information System (INIS)

    Zerbe, M.

    1992-01-01

    The purpose of the document is to present the importance of different categories of contrast media in radiography. Ionic and non-ionic contrast media are presented. Pharmacology and pathophysiology of Iodine contrast media with their effects on special organs of the body like the heart, vessels, lungs and nervous systems are explained. Paramagnetic contrast media used in NMR imaging are presented too. Emphasis is made on contrast media based on Gadolinium like Gd-DTPA, Gd-CL3, Gd-EDTA. Actions of Gd-DTPA applied to images in urography are pointed out

  14. The use of contrast media in computer tomography

    International Nuclear Information System (INIS)

    Galanski, M.; Cramer, B.M.; Drewes, G.

    1980-01-01

    There are a variety of applications for contrast media in CT. They can be used for better anatomic demonstration or for showing pathological processes. Nearly all available contrast media may be found useful. Intravenously injected renographic contrast media are most commonly employed. In addition to their inherent contrast, specific pharmaco-kinetic changes may be of diagnostic value. This adds some knowledge of function to the purely morphological information obtained by computer tomography. For this purpose, contrast has to be injected rapidly and a fast scanner must be used (so-called angio-CT). (orig.) [de

  15. JUST Revisited: Panchronic and Contrastive Insights

    Directory of Open Access Journals (Sweden)

    Manuela Romano

    2012-06-01

    Full Text Available Contrastive studies of cognate pragmatic markers involving modality have become increasingly salient in recent times. In describing semantic and discursive differences in different languages and language families, these studies are paving the way for a better understanding of grammaticalization, pragmaticalization and (intersubjectification paths. The present paper aims at contributing to the discussion by means of providing a synchronic and diachronic account of the marker JUST that combines semasiological and onomasiological insights. As thoroughly described in previous studies, JUST is a complex polycentric category in which overlapping nuances have been activated over time. In English and in other languages, the diachronic evolution of JUST involves an increasing semantic expansion from scalar to subjectified meanings and an increasing restriction in grammatical flexibility. However, polysemization and the emergence of grammaticalized readings seem to have gone further in English than in other languages. The present study, situated within the emerging field of panchronic cross-linguistic research on discourse markers, aims at ascertaining why.El estudio contrastivo de los marcadores pragmáticos de modalidad ocupa una posición central en el campo de la gramaticalización, la pragmaticalización y la (intersubjetivización, ya que permite trazar rutas de cambio a través de la descripción de peculiaridades semánticas y discursivas en distintas lenguas y familias lingüísticas. Este trabajo contribuye al debate ofreciendo un análisis semasiológico y onomasiológico del marcador JUST en sincronía y diacronía. Se trata de una categoría policéntrica en la que se han ido activando lecturas cruzadas a lo largo del tiempo. Su evolución está marcada, tanto en inglés como en otras lenguas, por una expansión semántica cada vez mayor, transitando desde lecturas escalares hacia lecturas subjetivizadas, y por una flexibilidad gramatical

  16. Intra-specific variations in expression of stress-related genes in beech progenies are stronger than drought-induced responses.

    Science.gov (United States)

    Carsjens, Caroline; Nguyen Ngoc, Quynh; Guzy, Jonas; Knutzen, Florian; Meier, Ina Christin; Müller, Markus; Finkeldey, Reiner; Leuschner, Christoph; Polle, Andrea

    2014-12-01

    Rapidly decreasing water availability as a consequence of climate change is likely to endanger the range of long-lived tree species. A pressing question is, therefore, whether adaptation to drought exists in important temperate tree species like European beech (Fagus sylvatica L.), a wide-spread, dominant forest tree in Central Europe. Here, five beech stands were selected along a precipitation gradient from moist to dry conditions. Neutral genetic markers revealed strong variation within and little differentiation between the populations. Natural regeneration from these stands was transferred to a common garden and used to investigate the expression of genes for abscisic acid (ABA)-related drought signaling [9-cis-epoxy-dioxygenase (NCED), protein phosphatase 2C (PP2C), early responsive to dehydration (ERD)] and stress protection [ascorbate peroxidase (APX), superoxide dismutase (SOD), aldehyde dehydrogenase (ALDH), glutamine amidotransferase (GAT)] that are involved in drought acclimation. We hypothesized that progenies from dry sites exhibit constitutively higher expression levels of ABA- and stress-related genes and are less drought responsive than progenies from moist sites. Transcript levels and stress responses (leaf area loss, membrane integrity) of well-irrigated and drought-stressed plants were measured during the early, mid- and late growing season. Principal component (PC) analysis ordered the beech progenies according to the mean annual precipitation at tree origin by the transcript levels of SOD, ALDH, GAT and ERD as major loadings along PC1. PC2 separated moist and drought treatments with PP2C levels as important loading. These results suggest that phosphatase-mediated signaling is flexibly acclimated to the current requirements, whereas stress compensatory measures exhibited genotypic variation, apparently underlying climate selection. In contrast to expectation, the drought responses were less pronounced than the progeny-related differences and the

  17. A survey of contrast media used in coronary angiograph

    International Nuclear Information System (INIS)

    Weikl, A.; Hubmann, M.

    1982-01-01

    In recent years, various contrast media have been developed for use in coronary angiography. These contrast media may be divided into ionic contrast media of high osmolality, those of low osmolality, and nonionic contrast materials. We conducted our own clinical studies with 40 patients. In random succession a standard contrast medium (ionic, of high osmolality) and a new-generation contrast medium (either nonionic or ionic with low osmolality) were injected into the right and left coronary arteries. After each injection we measured the systolic and diastolic blood pressure using a liquid-filled coronary catheter. In addition, the change in the length of the cardiac cycle was registered in terms of the R-R interval (in ms) and at the same time, leads I, II, and III of the ECG were recorded. We studied the influence of the various contrast media on the activity of ATPase in in vitro experiments, using Lasser and Lang's. When ionic contrast media of low osmolality and nonionic contrast media were utilized the heart rate showed no change. Disturbances of rhythm such as ventricular tachycardia or fibrillation were not observed. All of the contrast media used produced the same ECG changes. These changes can be ascribed to the inhibition of ATPase. The arterial blood pressure was lowered significantly only by ionic contrast media of high osmolality only. (orig.)

  18. Fundamental study of DSA images using gadolinium contrast agent

    International Nuclear Information System (INIS)

    Nagashima, Hiroyuki; Shiraishi, Akihisa; Igarashi, Hitoshi; Sakamoto, Hajime; Sano, Yoshitomo

    2002-01-01

    Most contrast agents used in digital subtraction angiography (DSA) are non-ionic iodinated contrast agents, which can cause severe side effects in patients with contraindications for iodine or allergic reactions to iodine. Therefore, DSA examinations using carbon dioxide gas or examinations done by magnetic resonance imaging (MRI) and ultrasound (US) were carried out in these patients. However, none of these examinations provided mages as clear as those of DSA with an iodinated contrast agent. We experienced DSA examination using a gadolinium contrast agent in a patient contraindicated for iodine. The patient had undergone MRI examination with a gadolinium contrast agent previously without side effects. The characteristics of gadolinium and the iodinated contrast agent were compared, and the DSA images obtained clinically using these media were also evaluated. The signal-to-noise (SN) ratio of the gadolinium contrast agent was the highest at tube voltages of 70 to 80 kilovolts and improved slightly when the image intensifier (I.I.) entrance dose was greater than 300 μR (77.4 nC/kg). The dilution ratios of five iodinated contrast agents showed the same S/N value as the undiluted gadolinium contrast agent. Clinically, the images obtained showed a slight decrease in contrast but provided the data necessary to make a diagnosis and made it possible to obtain interventional radiology (IVR) without any side effects. DSA examinations using a gadolinium contrast agent have some benefit with low risk and are thought to be useful for patients contraindicated for iodine. (author)

  19. Spatiotemporal Characteristics for the Depth from Luminance Contrast

    Directory of Open Access Journals (Sweden)

    Kazuya Matsubara

    2011-05-01

    Full Text Available Images with higher luminance contrast tend to be perceived closer in depth. To investigate a spatiotemporal characteristic of this effect, we evaluated subjective depth of a test stimulus with various spatial and temporal frequencies. For the purpose, the depth of a reference stimulus was matched to that of the test stimulus by changing the binocular disparity. The results showed that the test stimulus was perceived closer with higher luminance contrast for all conditions. Contrast efficiency was obtained from the contrast that provided the subjective depth for each spatiotemporal frequency. The shape of the contrast efficiency function was spatially low-pass and temporally band-pass. This characteristic is different from the one measure for a detection task. This suggests that only subset of contrast signals are used for depth from contrast.

  20. MRI and CT contrast media extravasation: A systematic review.

    Science.gov (United States)

    Heshmatzadeh Behzadi, Ashkan; Farooq, Zerwa; Newhouse, Jeffery H; Prince, Martin R

    2018-03-01

    This systematic review combines data from multiple papers on contrast media extravasation to identify factors contributing to increased extravasation risk. Data were extracted from 17 papers reporting 2191 extravasations in 1,104,872 patients (0.2%) undergoing computed tomography (CT) or magnetic resonance imaging (MRI). Extravasation rates were 0.045% for gadolinium-based contrast agents (GBCA) and nearly 6-fold higher, 0.26% for iodinated contrast agents. Factors associated with increased contrast media extravasations included: older age, female gender, using an existing intravenous (IV) instead of placing a new IV in radiology, in-patient status, use of automated power injection, high injection rates, catheter location, and failing to warm up the more viscous contrast media to body temperature. Contrast media extravasation is infrequent but nearly 6 times less frequent with GBCA for MRI compared with iodinated contrast used in CT.