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Sample records for binocular rivalry reveals

  1. Attentional Modulation of Binocular Rivalry

    OpenAIRE

    Chris ePaffen; David eAlais

    2011-01-01

    Ever since Wheatstone initiated the scientific study of binocular rivalry, it has been debated whether the phenomenon is under attentional control. In recent years, the issue of attentional modulation of binocular rivalry has seen a revival. Here we review the classical studies as well as recent advances in the study of attentional modulation of binocular rivalry. We show that (1) voluntary control over binocular rivalry is possible, yet limited, (2) both endogenous and exogenous attention in...

  2. Binocular rivalry from invisible patterns.

    Science.gov (United States)

    Zou, Jinyou; He, Sheng; Zhang, Peng

    2016-07-26

    Binocular rivalry arises when incompatible images are presented to the two eyes. If the two eyes' conflicting features are invisible, leading to identical perceptual interpretations, does rivalry competition still occur? Here we investigated whether binocular rivalry can be induced from conflicting but invisible spatial patterns. A chromatic grating counterphase flickering at 30 Hz appeared uniform, but produced significant tilt aftereffect and orientation-selective adaptation. The invisible pattern also generated significant BOLD activities in the early visual cortex, with minimal response in the parietal and frontal cortical areas. Compared with perceptually matched uniform stimuli, a monocularly presented invisible chromatic grating enhanced the rivalry competition with a low-contrast visible grating presented to the other eye. Furthermore, switching from a uniform field to a perceptually matched invisible chromatic grating produced interocular suppression at approximately 200 ms after onset of the invisible grating. Experiments using briefly presented monocular probes revealed evidence for sustained rivalry competition between two invisible gratings during continuous dichoptic presentations. These findings indicate that even without visible interocular conflict, and with minimal engagement of frontoparietal cortex and consciousness related top-down feedback, perceptually identical patterns with invisible conflict features produce rivalry competition in the early visual cortex. PMID:27354535

  3. Hierarchy of cortical responses underlying binocular rivalry

    OpenAIRE

    Lee, Sang-Hun; Blake, Randolph; Heeger, David J.

    2007-01-01

    During binocular rivalry, physical stimulation is dissociated from conscious visual awareness. Human brain imaging reveals a tight linkage between the neural events in human primary visual cortex (V1) and the dynamics of perceptual waves during transitions in dominance during binocular rivalry. Here, we report results from experiments in which observers’ attention was diverted from the rival stimuli, implying that: competition between two rival stimuli involves neural circuits in V1, and atte...

  4. Neurons that detect interocular conflict during binocular rivalry revealed with EEG.

    Science.gov (United States)

    Katyal, Sucharit; Engel, Stephen A; He, Bin; He, Sheng

    2016-01-01

    When the two eyes view incompatible images, perception alternates between them. What neural computations underlie this binocular rivalry? Perceptual alternations may simply reflect competition between the sets of monocular neurons that respond to each image, with the stronger driving perception. Here, we test an alternative hypothesis, that the computations that resolve rivalry make use of an active signal that reflects interocular conflict. Images presented to each eye were flickered at different frequencies while we measured steady-state visually evoked potentials (SSVEP). Signals at frequencies that are combinations of the two input frequencies can arise only from binocular neurons. In a first experiment, we measured energy at these "intermodulation" frequencies during binocular rivalry and found it to be highest immediately before rivalry restarted following a period of incomplete resolution of rivalry (a "mixed" percept). This suggests that the intermodulation signals may arise from neurons important for resolving the conflict between the two eyes' inputs. In a second experiment, we tested whether the intermodulation signal arose from neurons that measure interocular conflict by parametrically increasing conflict while simultaneously reducing image contrast. The activity of neurons that receive input from both eyes but are not sensitive to conflict should reduce monotonically as contrast decreases. The intermodulation response, however, peaked at intermediate levels of conflict, suggesting that it arises in part from neurons that respond to interocular conflict. Binocular rivalry appears to depend on an active mechanism that detects interocular conflict, whose levels of activity can be measured by the intermodulation frequencies of the SSVEP. PMID:26891825

  5. Binocular rivalry produced by temporal frequency differences

    OpenAIRE

    Alais, David; Parker, Amanda

    2012-01-01

    When the eyes view images that are sufficiently different to prevent binocular fusion, binocular rivalry occurs and the images are seen sequentially in a stochastic alternation. Here we examine whether temporal frequency differences will trigger binocular rivalry by presenting two dynamic random-pixel arrays that are spatially matched but which modulate temporally at two different rates. We found that binocular rivalry between the two temporal frequencies did indeed occur, provided the freque...

  6. When can attention influence binocular rivalry?

    Science.gov (United States)

    Dieter, Kevin C; Melnick, Michael D; Tadin, Duje

    2015-08-01

    Attentional influence over perception is particularly pronounced when sensory stimulation is ambiguous, where attention can reduce stimulus uncertainty and promote a stable interpretation of the world. However, binocular rivalry, an extensively studied visual ambiguity, has proved to be comparatively resistant to attentional modulation. We hypothesize that this apparent inconsistency reflects fluctuations in the degree of unresolved competition during binocular rivalry. Namely, attentional influence over rivalry dynamics should be limited to phases of relatively unresolved stimulus competition, such as ends of individual dominance periods. We found that transient, feature-based cues congruent with the dominant stimulus prolonged dominance durations, while cues matching the suppressed stimulus hastened its return to dominance. Notably, the effect of cues depended on when the cues are presented. Cues presented late, but not early, during a given episode of perceptual dominance influenced rivalry dynamics. This temporal pattern mirrors known changes in the relative competitive dynamics of rival stimuli, revealing that selective effects occur only during temporal windows containing weak resolution of visual competition. In conclusion, these findings reveal that unresolved competition, which gates attention across a variety of domains, is also crucial in determining the susceptibility of binocular rivalry to selective influences. PMID:25898898

  7. Interactions between binocular rivalry and Gestalt formation

    NARCIS (Netherlands)

    Weert, C.M.; Snoeren, P.R.; Koning, Arno

    2005-01-01

    A question raised a long time ago in binocular rivalry research is whether the phenomenon of binocular rivalry is purely determined by local stimulus properties or that global stimulus properties also play a role. More specifically: do coherent features in a stimulus influence rivalrous behavior? Af

  8. Binocular rivalry produced by temporal frequency differences

    OpenAIRE

    David eAlais; Parker, Amanda L.

    2012-01-01

    Binocular rivalry occurs when each eye views images that are markedly different. Rather than seeing a binocular fusion of the two, each image is seen exclusively in a stochastic alternation of the monocular images. Here we examine whether temporal frequency differences will trigger binocular rivalry by presenting two random dot arrays that are spatially matched but which modulate temporally at two different rates and contained no net translation. We found that a perceptual alternation between...

  9. Binocular rivalry produced by temporal frequency differences

    Directory of Open Access Journals (Sweden)

    David eAlais

    2012-07-01

    Full Text Available Binocular rivalry occurs when each eye views images that are markedly different. Rather than seeing a binocular fusion of the two, each image is seen exclusively in a stochastic alternation of the monocular images. Here we examine whether temporal frequency differences will trigger binocular rivalry by presenting two random dot arrays that are spatially matched but which modulate temporally at two different rates and contained no net translation. We found that a perceptual alternation between the two temporal frequencies did indeed occur, provided the frequencies were sufficiently different, indicating that temporal information can produce binocular rivalry in the absence of spatial conflict. This finding is discussed with regard to the dependence of rivalry on conflict between spatial and temporal channels.

  10. Insights from Intermittent Binocular Rivalry and EEG

    OpenAIRE

    Pitts, Michael A.; Juliane eBritz

    2011-01-01

    Novel stimulation and analytical approaches employed in EEG studies of ambiguous figures have recently been applied to binocular rivalry. The combination of intermittent stimulus presentation and EEG source imaging has begun to shed new light on the neural underpinnings of binocular rivalry. Here, we review the basics of the intermittent paradigm and highlight methodological issues important for interpreting previous results and designing future experiments. We then outline current analytical...

  11. What is Grouping during Binocular Rivalry?

    OpenAIRE

    Sjoerd Martin Stuit; Chris ePaffen; Maarten evan der Smagt; Frans eVerstraten

    2011-01-01

    During binocular rivalry, perception alternates between dissimilar images presented dichoptically. Although perception during rivalry is believed to originate from competition at a local level, different rivalry zones are not independent: rival targets that are spaced apart but have similar features tend to be dominant at the same time. We investigated grouping of spatially separated rival targets presented to the same or to different eyes and presented in the same or in different hemifields....

  12. Insights from intermittent binocular rivalry and EEG

    Directory of Open Access Journals (Sweden)

    Michael A Pitts

    2011-09-01

    Full Text Available Novel stimulation and analytical approaches employed in EEG studies of ambiguous figures have recently been applied to binocular rivalry. The combination of intermittent stimulus presentation and EEG source imaging has begun to shed new light on the neural underpinnings of binocular rivalry. Here, we review the basics of the intermittent paradigm and highlight methodological issues important for interpreting previous results and designing future experiments. We then outline current analytical approaches, including EEG microstates, event-related potentials, and statistically-based source estimation, and propose a spatio-temporal model that integrates findings from several studies. Finally, we discuss the advantages and limitations of using binocular rivalry as a tool to investigate the neural basis of perceptual awareness.

  13. Individual differences in the temporal dynamics of binocular rivalry and stimulus rivalry

    OpenAIRE

    Patel, Vaama; Stuit, Sjoerd; Blake, Randolph

    2015-01-01

    Binocular rivalry and stimulus rivalry are two forms of perceptual instability that arise when the visual system is confronted with conflicting stimulus information. In the case of binocular rivalry, dissimilar monocular stimuli are presented to the two eyes for an extended period of time, whereas for stimulus rivalry the dissimilar monocular stimuli are exchanged rapidly and repetitively between the eyes during extended viewing. With both forms of rivalry, one experiences extended durations ...

  14. Individual Differences in Temporal Dynamics of Binocular Rivalry and of Stimulus Rivalry

    OpenAIRE

    Patel, Vaama; Stuit, Sjoerd; Blake, Randolph

    2015-01-01

    Binocular rivalry and stimulus rivalry are two forms of perceptual instability that arise when the visual system is confronted with conflicting stimulus information. In the case of binocular rivalry, dissimilar monocular stimuli are presented to the two eyes for an extended period of time, whereas for stimulus rivalry the dissimilar monocular stimuli are exchanged rapidly and repetitively between the eyes during extended viewing. With both forms of rivalry, one experiences extended durations ...

  15. Understanding attentional modulation of binocular rivalry: a framework based on biased competition

    OpenAIRE

    Kevin Conrad Dieter; Duje eTadin

    2011-01-01

    Starting from early scientific explorations of binocular rivalry, researchers have wondered about the degree to which an observer can exert voluntary attentional control over rivalry dynamics. The answer to this question would not only reveal the extent to which we may determine our own conscious visual experience, but also advance our understanding of the neural mechanisms underlying binocular rivalry. Classic studies, intriguingly, reached contradictory conclusions, ranging from an absence ...

  16. Understanding Attentional Modulation of Binocular Rivalry: A Framework Based on Biased Competition

    OpenAIRE

    Dieter, Kevin Conrad; Tadin, Duje

    2011-01-01

    Starting from early scientific explorations of binocular rivalry, researchers have wondered about the degree to which an observer can exert voluntary attentional control over rivalry dynamics. The answer to this question would not only reveal the extent to which we may determine our own conscious visual experience, but also advance our understanding of the neural mechanisms underlying binocular rivalry. Classic studies, intriguingly, reached contradictory conclusions, ranging from an absence ...

  17. Quantum formalism to describe binocular rivalry.

    Science.gov (United States)

    Manousakis, Efstratios

    2009-11-01

    On the basis of the general character and operation of the process of perception, a formalism is sought to mathematically describe the subjective or abstract/mental process of perception. It is shown that the formalism of orthodox quantum theory of measurement, where the observer plays a key role, is a broader mathematical foundation which can be adopted to describe the dynamics of the subjective experience. The mathematical formalism describes the psychophysical dynamics of the subjective or cognitive experience as communicated to us by the subject. Subsequently, the formalism is used to describe simple perception processes and, in particular, to describe the probability distribution of dominance duration obtained from the testimony of subjects experiencing binocular rivalry. Using this theory and parameters based on known values of neuronal oscillation frequencies and firing rates, the calculated probability distribution of dominance duration of rival states in binocular rivalry under various conditions is found to be in good agreement with available experimental data. This theory naturally explains an observed marked increase in dominance duration in binocular rivalry upon periodic interruption of stimulus and yields testable predictions for the distribution of perceptual alteration in time. PMID:19520143

  18. Individual differences in the temporal dynamics of binocular rivalry and stimulus rivalry

    NARCIS (Netherlands)

    Patel, Vaama; Stuit, Sjoerd; Blake, Randolph

    2015-01-01

    Binocular rivalry and stimulus rivalry are two forms of perceptual instability that arise when the visual system is confronted with conflicting stimulus information. In the case of binocular rivalry, dissimilar monocular stimuli are presented to the two eyes for an extended period of time, whereas f

  19. Individual differences in the temporal dynamics of binocular rivalry and stimulus rivalry.

    Science.gov (United States)

    Patel, Vaama; Stuit, Sjoerd; Blake, Randolph

    2015-04-01

    Binocular rivalry and stimulus rivalry are two forms of perceptual instability that arise when the visual system is confronted with conflicting stimulus information. In the case of binocular rivalry, dissimilar monocular stimuli are presented to the two eyes for an extended period of time, whereas for stimulus rivalry the dissimilar monocular stimuli are exchanged rapidly and repetitively between the eyes during extended viewing. With both forms of rivalry, one experiences extended durations of exclusive perceptual dominance that fluctuate between the two stimuli. Whether these two forms of rivalry arise within different stages of visual processing has remained debatable. Using an individual-differences approach, we found that both stimulus rivalry and binocular rivalry exhibited same-shaped distributions of dominance durations among a sample of 30 observers and, moreover, that the dominance durations measured during binocular and stimulus rivalry were significantly correlated among our sample of observers. Furthermore, we found a significant, positive correlation between alternation rate in binocular rivalry and the incidence of stimulus rivalry. These results suggest that the two forms of rivalry may be tapping common neural mechanisms, or at least different mechanisms with comparable time constants. It remains to be learned just why the incidences of binocular rivalry and stimulus rivalry vary so greatly among people. PMID:25092387

  20. Removal of monocular interactions equates rivalry behavior for monocular, binocular, and stimulus rivalries

    OpenAIRE

    van Boxtel, J.J.A.; Knapen, T.H.J.; Erkelens, C. J.; Ee, R

    2008-01-01

    When the two eyes are presented with conflicting stimuli, perception starts to fluctuate over time (i.e., binocular rivalry). A similar fluctuation occurs when two patterns are presented to a single eye (i.e., monocular rivalry), or when they are swapped rapidly and repeatedly between the eyes (i.e., stimulus rivalry). Although all these cases lead to rivalry, in quantitative terms these modes of rivalry are generally found to differ significantly. We studied these different modes of rivalry ...

  1. Predictive Coding Explains Binocular Rivalry: An Epistemological Review

    Science.gov (United States)

    Hohwy, Jakob; Roepstorff, Andreas; Friston, Karl

    2008-01-01

    Binocular rivalry occurs when the eyes are presented with different stimuli and subjective perception alternates between them. Though recent years have seen a number of models of this phenomenon, the mechanisms behind binocular rivalry are still debated and we still lack a principled understanding of why a cognitive system such as the brain should…

  2. What causes alternations in dominance during binocular rivalry?

    OpenAIRE

    Kang, Min-Suk; Blake, Randolph

    2010-01-01

    Several mechanisms have been proposed to account for perceptual alterations during binocular rivalry, including neural adaptation and neural noise. However, the importance of neural adaptation for producing perceptual alterations has been challenged in several articles (Y.-J. Kim, Grabowecky, & Suzuki, 2006; Moreno-Bote, Rinzel, & Rubin, 2007). We devised an “online” adaptation procedure to reexamine the role of adaptation in binocular rivalry. Periods of adaptation inserted into rivalry obse...

  3. The Role of Temporally Coarse Form Processing during Binocular Rivalry

    OpenAIRE

    van Boxtel, Jeroen J. A.; David Alais; Erkelens, Casper J.; Raymond van Ee

    2008-01-01

    Presenting the eyes with spatially mismatched images causes a phenomenon known as binocular rivalry-a fluctuation of awareness whereby each eye's image alternately determines perception. Binocular rivalry is used to study interocular conflict resolution and the formation of conscious awareness from retinal images. Although the spatial determinants of rivalry have been well-characterized, the temporal determinants are still largely unstudied. We confirm a previous observation that conflicting ...

  4. Bistable Percepts in the Brain: fMRI Contrasts Monocular Pattern Rivalry and Binocular Rivalry

    OpenAIRE

    Athena Buckthought; Samuel Jessula; Mendola, Janine D.

    2011-01-01

    The neural correlates of binocular rivalry have been actively debated in recent years, and are of considerable interest as they may shed light on mechanisms of conscious awareness. In a related phenomenon, monocular rivalry, a composite image is shown to both eyes. The subject experiences perceptual alternations in which the two stimulus components alternate in clarity or salience. The experience is similar to perceptual alternations in binocular rivalry, although the reduction in visibility ...

  5. HIERARCHICAL SPATIO-TEMPORAL DYNAMICS OF A CHAOTIC NEURAL NETWORK FOR MULTISTABLE BINOCULAR RIVALRY

    OpenAIRE

    KAKIMOTO, YUTA; Aihara, Kazuyuki

    2009-01-01

    Binocular rivalry is perceptual alternation that occurs when different visual images are presented to each eye. Despite the intensive studies, the mechanism of binocular rivalry still remains unclear. In multistable binocular rivalry, which is a special case of binocular rivalry, it is known that the perceptual alternation between paired patterns is more frequent than that between unpaired patterns. This result suggests that perceptual transition in binocular rivalry is not a simple random pr...

  6. Bistable percepts in the brain: FMRI contrasts monocular pattern rivalry and binocular rivalry.

    Directory of Open Access Journals (Sweden)

    Athena Buckthought

    Full Text Available The neural correlates of binocular rivalry have been actively debated in recent years, and are of considerable interest as they may shed light on mechanisms of conscious awareness. In a related phenomenon, monocular rivalry, a composite image is shown to both eyes. The subject experiences perceptual alternations in which the two stimulus components alternate in clarity or salience. The experience is similar to perceptual alternations in binocular rivalry, although the reduction in visibility of the suppressed component is greater for binocular rivalry, especially at higher stimulus contrasts. We used fMRI at 3T to image activity in visual cortex while subjects perceived either monocular or binocular rivalry, or a matched non-rivalrous control condition. The stimulus patterns were left/right oblique gratings with the luminance contrast set at 9%, 18% or 36%. Compared to a blank screen, both binocular and monocular rivalry showed a U-shaped function of activation as a function of stimulus contrast, i.e. higher activity for most areas at 9% and 36%. The sites of cortical activation for monocular rivalry included occipital pole (V1, V2, V3, ventral temporal, and superior parietal cortex. The additional areas for binocular rivalry included lateral occipital regions, as well as inferior parietal cortex close to the temporoparietal junction (TPJ. In particular, higher-tier areas MT+ and V3A were more active for binocular than monocular rivalry for all contrasts. In comparison, activation in V2 and V3 was reduced for binocular compared to monocular rivalry at the higher contrasts that evoked stronger binocular perceptual suppression, indicating that the effects of suppression are not limited to interocular suppression in V1.

  7. A Model of Binocular Rivalry and Cross-orientation Suppression

    OpenAIRE

    Said, Christopher P.; Heeger, David J.

    2013-01-01

    Binocular rivalry and cross-orientation suppression are well-studied forms of competition in visual cortex, but models of these two types of competition are in tension with one another. Binocular rivalry occurs during the presentation of dichoptic grating stimuli, where two orthogonal gratings presented separately to the two eyes evoke strong alternations in perceptual dominance. Cross-orientation suppression occurs during the presentation of plaid stimuli, where the responses to a component ...

  8. Genetic contribution to individual variation in binocular rivalry rate

    OpenAIRE

    Miller, Steven M.; Hansell, Narelle K.; Ngo, Trung T.; Liu, Guang B.; Pettigrew, John D.; Martin, Nicholas G.; Wright, Margaret J.

    2010-01-01

    Binocular rivalry occurs when conflicting images are presented in corresponding locations of the two eyes. Perception alternates between the images at a rate that is relatively stable within individuals but that varies widely between individuals. The determinants of this variation are unknown. In addition, slow binocular rivalry has been demonstrated in bipolar disorder, a psychiatric condition with high heritability. The present study therefore examined whether there is a genetic contributio...

  9. An integrated framework of spatiotemporal dynamics of binocular rivalry

    OpenAIRE

    Min-Suk Kang; Randolph Blake

    2011-01-01

    Fluctuations in perceptual dominance during binocular rivalry exhibit several hallmark characteristics. First, dominance switches are not periodic but, instead, stochastic: perception changes unpredictably. Second, despite being stochastic, average durations of rivalry dominance vary dependent on the strength of the rival stimuli: variations in contrast, luminance or spatial frequency produce predictable changes in average dominance durations and, hence, in alternation rate. Third, perceptual...

  10. An Integrated Framework of Spatiotemporal Dynamics of Binocular Rivalry

    OpenAIRE

    Kang, Min-Suk; Blake, Randolph

    2011-01-01

    Fluctuations in perceptual dominance during binocular rivalry exhibit several hallmark characteristics. First, dominance switches are not periodic but, instead, stochastic: perception changes unpredictably. Second, despite being stochastic, average durations of rivalry dominance vary dependent on the strength of the rival stimuli: variations in contrast, luminance, or spatial frequency produce predictable changes in average dominance durations and, hence, in alternation rate. Third, perceptua...

  11. Acute Alcohol Drinking Promotes Piecemeal Percepts during Binocular Rivalry.

    Science.gov (United States)

    Cao, Dingcai; Zhuang, Xiaohua; Kang, Para; Hong, Sang W; King, Andrea C

    2016-01-01

    Binocular rivalry refers to perceptual alternation when two eyes view different images. One of the potential percepts during binocular rivalry is a spatial mosaic of left- and right-eye images, known as piecemeal percepts, which may result from localized rivalries between small regions in the left- and right-eye images. It is known that alcohol increases inhibitory neurotransmission, which may reduce the number of alternations during binocular rivalry. However, it is unclear whether alcohol affects rivalry dynamics in the same manner for both coherent percepts (i.e., percepts of complete left or right images) and piecemeal percepts. To address this question, the present study measured the dynamics of binocular rivalry before and after 15 moderate-to-heavy social drinkers consumed an intoxicating dose of alcohol versus a placebo beverage. Both simple rivalrous stimuli consisting of gratings with different orientations, and complex stimuli consisting of a face or a house were tested to examine alcohol effects on rivalry as a function of stimulus complexity. Results showed that for both simple and complex stimuli, alcohol affects coherent and piecemeal percepts differently. More specifically, alcohol reduced the number of coherent percepts but not the mean dominance duration of coherent percepts. In contrast, for piecemeal percepts, alcohol increased the mean dominance duration but not the number of piecemeal percepts. These results suggested that alcohol drinking may selectively affect the dynamics of transitional period of binocular rivalry by increasing the duration of piecemeal percepts, leading to a reduction in the number of coherent percepts. The differential effect of alcohol on the dynamics of coherent and piecemeal percepts cannot be accounted for by alcohol's effect on a common inhibitory mechanism. Other mechanisms, such as increasing neural noise, are needed to explain alcohol's effect on the dynamics of binocular rivalry. PMID:27092096

  12. Acute Alcohol Drinking Promotes Piecemeal Percepts during Binocular Rivalry

    Science.gov (United States)

    Cao, Dingcai; Zhuang, Xiaohua; Kang, Para; Hong, Sang W.; King, Andrea C.

    2016-01-01

    Binocular rivalry refers to perceptual alternation when two eyes view different images. One of the potential percepts during binocular rivalry is a spatial mosaic of left- and right-eye images, known as piecemeal percepts, which may result from localized rivalries between small regions in the left- and right-eye images. It is known that alcohol increases inhibitory neurotransmission, which may reduce the number of alternations during binocular rivalry. However, it is unclear whether alcohol affects rivalry dynamics in the same manner for both coherent percepts (i.e., percepts of complete left or right images) and piecemeal percepts. To address this question, the present study measured the dynamics of binocular rivalry before and after 15 moderate-to-heavy social drinkers consumed an intoxicating dose of alcohol versus a placebo beverage. Both simple rivalrous stimuli consisting of gratings with different orientations, and complex stimuli consisting of a face or a house were tested to examine alcohol effects on rivalry as a function of stimulus complexity. Results showed that for both simple and complex stimuli, alcohol affects coherent and piecemeal percepts differently. More specifically, alcohol reduced the number of coherent percepts but not the mean dominance duration of coherent percepts. In contrast, for piecemeal percepts, alcohol increased the mean dominance duration but not the number of piecemeal percepts. These results suggested that alcohol drinking may selectively affect the dynamics of transitional period of binocular rivalry by increasing the duration of piecemeal percepts, leading to a reduction in the number of coherent percepts. The differential effect of alcohol on the dynamics of coherent and piecemeal percepts cannot be accounted for by alcohol’s effect on a common inhibitory mechanism. Other mechanisms, such as increasing neural noise, are needed to explain alcohol’s effect on the dynamics of binocular rivalry. PMID:27092096

  13. On the role of attention in binocular rivalry: electrophysiological evidence.

    Directory of Open Access Journals (Sweden)

    Urte Roeber

    Full Text Available During binocular rivalry visual consciousness fluctuates between two dissimilar monocular images. We investigated the role of attention in this phenomenon by comparing event-related potentials (ERPs when binocular-rivalry stimuli were attended with when they were unattended. Stimuli were dichoptic, orthogonal gratings that yielded binocular rivalry and dioptic, identically oriented gratings that yielded binocular fusion. Events were all possible orthogonal changes in orientation of one or both gratings. We had two attention conditions: In the attend-to-grating condition, participants had to report changes in perceived orientation, focussing their attention on the gratings. In the attend-to-fixation condition participants had to report changes in a central fixation target, taking attention away from the gratings. We found, surprisingly, that attending to rival gratings yielded a smaller ERP component (the N1, from 160-210 ms than attending to the fixation target. To explain this paradoxical effect of attention, we propose that rivalry occurs in the attend-to-fixation condition (we found an ERP signature of rivalry in the form of a sustained negativity from 210-300 ms but that the mechanism processing the stimulus changes is more adapted in the attend-to-grating condition than in the attend-to-fixation condition. This is consistent with the theory that adaptation gives rise to changes of visual consciousness during binocular rivalry.

  14. Binocular Onset Rivalry at the Time of Saccades and Stimulus Jumps

    OpenAIRE

    Kalisvaart, Joke P.; Rampersad, Sumientra M.; Jeroen Goossens

    2011-01-01

    Recent studies suggest that binocular rivalry at stimulus onset, so called onset rivalry, differs from rivalry during sustained viewing. These observations raise the interesting question whether there is a relation between onset rivalry and rivalry in the presence of eye movements. We therefore studied binocular rivalry when stimuli jumped from one visual hemifield to the other, either through a saccade or through a passive stimulus displacement, and we compared rivalry after such displacemen...

  15. An integrated framework of spatiotemporal dynamics of binocular rivalry

    Directory of Open Access Journals (Sweden)

    Min-Suk Kang

    2011-08-01

    Full Text Available Fluctuations in perceptual dominance during binocular rivalry exhibit several hallmark characteristics. First, dominance switches are not periodic but, instead, stochastic: perception changes unpredictably. Second, despite being stochastic, average durations of rivalry dominance vary dependent on the strength of the rival stimuli: variations in contrast, luminance or spatial frequency produce predictable changes in average dominance durations and, hence, in alternation rate. Third, perceptual switches originate locally and spread globally over time, sometimes as traveling waves of dominance: rivalry transitions are spatio-temporal events. This essay 1 reviews recent advances in our understanding of the bases of these three hallmark characteristics of binocular rivalry dynamics and 2 provides an integrated framework to account for those dynamics using cooperative and competitive spatial interactions among local neural circuits distributed over the visual field’s retinotopic map. We close with speculations about how that framework might incorporate top-down influences on rivalry dynamics.

  16. Removal of monocular interactions equates rivalry behavior for monocular, binocular, and stimulus rivalries

    NARCIS (Netherlands)

    van Boxtel, J.J.A.; Knapen, T.H.J.; Erkelens, C.J.; van Ee, R.

    2008-01-01

    When the two eyes are presented with conflicting stimuli, perception starts to fluctuate over time (i.e., binocular rivalry). A similar fluctuation occurs when two patterns are presented to a single eye (i.e., monocular rivalry), or when they are swapped rapidly and repeatedly between the eyes (i.e.

  17. Retinotopic and non-retinotopic stimulus encoding in binocular rivalry and the involvement of feedback

    OpenAIRE

    van Boxtel, J.J.A.; Alais, D.; Ee, R

    2008-01-01

    Adaptation is one of the key constituents of the perceptual alternation process during binocular rivalry, as it has been shown that preadapting one of the rivaling pairs before rivalry onset biases perception away from the adapted stimulus during rivalry. We investigated the influence of retinotopic and spatiotopic preadaptation on binocular rivalry. We show that for grating stimuli, preadaptation only influences rivalry when adaptation and rivalry locations are retinotopically matched. With ...

  18. Binocular rivalry alternations and their relation to visual adaptation

    OpenAIRE

    Daphne eRoumani; Konstantinos eMoutoussis

    2012-01-01

    When different stimuli are presented dichoptically, perception alternates between the two in a stochastic manner. After a long-lasting and rigorous debate, there is growing consensus that this phenomenon, known as binocular rivalry, is the result of a dynamic competition occurring at multiple levels of the visual hierarchy. The role of low- and high-level adaptation mechanisms in controlling these perceptual alternations has been a key issue in the rivalry literature. Both types of adaptatio...

  19. Predictive context influences perceptual selection during binocular rivalry

    Directory of Open Access Journals (Sweden)

    Rachel N Denison

    2011-12-01

    Full Text Available Prediction may be a fundamental principle of sensory processing: it has been proposed that the brain continuously generates predictions about forthcoming sensory information. However, little is known about how prediction contributes to the selection of a conscious percept from among competing alternatives. Here, we used binocular rivalry to investigate the effects of prediction on perceptual selection. In binocular rivalry, incompatible images presented to the two eyes result in a perceptual alternation between the images, even though the visual stimuli remain constant. If predictive signals influence the competition between neural representations of rivalrous images, this influence should generate a bias in perceptual selection that depends on predictive context. To manipulate predictive context, we developed a novel binocular rivalry paradigm in which rivalrous test images were immediately preceded by a sequence of context images presented identically to the two eyes. One of the test images was consistent with the preceding image sequence (it was the expected next image in the series, and the other was inconsistent (non-predicted. We found that human observers were more likely to perceive the consistent image at the onset of rivalry, suggesting that predictive context biased selection in favor of the predicted percept. This prediction effect was distinct from the effects of adaptation to stimuli presented before the binocular rivalry test. In addition, perceptual reports were speeded for predicted percepts relative to non-predicted percepts. These results suggest that predictive signals related to visual stimulus history exist at neural sites that can bias conscious perception during binocular rivalry. Our paradigm provides a new way to study how prior information and incoming sensory information combine to generate visual percepts.

  20. Binocular onset rivalry at the time of saccades and stimulus jumps.

    NARCIS (Netherlands)

    Kalisvaart, J.P.; Rampersad, S.M.; Goossens, H.H.L.M.

    2011-01-01

    Recent studies suggest that binocular rivalry at stimulus onset, so called onset rivalry, differs from rivalry during sustained viewing. These observations raise the interesting question whether there is a relation between onset rivalry and rivalry in the presence of eye movements. We therefore stud

  1. The 'laws' of binocular rivalry: 50 years of Levelt's propositions.

    Science.gov (United States)

    Brascamp, J W; Klink, P C; Levelt, W J M

    2015-04-01

    It has been fifty years since Levelt's monograph On Binocular Rivalry (1965) was published, but its four propositions that describe the relation between stimulus strength and the phenomenology of binocular rivalry remain a benchmark for theorists and experimentalists even today. In this review, we will revisit the original conception of the four propositions and the scientific landscape in which this happened. We will also provide a brief update concerning distributions of dominance durations, another aspect of Levelt's monograph that has maintained a prominent presence in the field. In a critical evaluation of Levelt's propositions against current knowledge of binocular rivalry we will then demonstrate that the original propositions are not completely compatible with what is known today, but that they can, in a straightforward way, be modified to encapsulate the progress that has been made over the past fifty years. The resulting modified, propositions are shown to apply to a broad range of bistable perceptual phenomena, not just binocular rivalry, and they allow important inferences about the underlying neural systems. We argue that these inferences reflect canonical neural properties that play a role in visual perception in general, and we discuss ways in which future research can build on the work reviewed here to attain a better understanding of these properties. PMID:25749677

  2. Symbolic Magnitude Modulates Perceptual Strength in Binocular Rivalry

    Science.gov (United States)

    Paffen, Chris L. E.; Plukaard, Sarah; Kanai, Ryota

    2011-01-01

    Basic aspects of magnitude (such as luminance contrast) are directly represented by sensory representations in early visual areas. However, it is unclear how symbolic magnitudes (such as Arabic numerals) are represented in the brain. Here we show that symbolic magnitude affects binocular rivalry: perceptual dominance of numbers and objects of…

  3. Binocular Rivalry in a Competitive Neural Network with Synaptic Depression

    KAUST Repository

    Kilpatrick, Zachary P.

    2010-01-01

    We study binocular rivalry in a competitive neural network with synaptic depression. In particular, we consider two coupled hypercolums within primary visual cortex (V1), representing orientation selective cells responding to either left or right eye inputs. Coupling between hypercolumns is dominated by inhibition, especially for neurons with dissimilar orientation preferences. Within hypercolumns, recurrent connectivity is excitatory for similar orientations and inhibitory for different orientations. All synaptic connections are modifiable by local synaptic depression. When the hypercolumns are driven by orthogonal oriented stimuli, it is possible to induce oscillations that are representative of binocular rivalry. We first analyze the occurrence of oscillations in a space-clamped version of the model using a fast-slow analys is, taking advantage of the fact that depression evolves much slower than population activity. We th en analyze the onset of oscillations in the full spatially extended system by carrying out a piecewise smooth stability analysis of single (winner-take-all) and double (fusion) bumps within the network. Although our stability analysis takes into account only instabilities associated with real eigenvalues, it identifies points of instability that are consistent with what is found numerically. In particular, we show that, in regions of parameter space where double bumps are unstable and no single bumps exist, binocular rivalry can arise as a slow alternation between either population supporting a bump. © 2010 Society for Industrial and Applied Mathematics.

  4. Action imitation changes perceptual alternations in binocular rivalry.

    Directory of Open Access Journals (Sweden)

    Enrico Di Pace

    Full Text Available Binocular rivalry is a visual phenomenon in which perception alternates between two different monocular images presented to each of the two eyes. Here, we propose using this phenomenon as a method to study the relation between action execution and action perception. In our experiment, a simple background (a checkerboard was contrasted with a video representing a hand continuously grasping and releasing a ball. In Experiment 1, our subjects were asked to reproduce the perceived movement with their right hand whenever they became aware of it and to stop doing this when the checkerboard dominated. Our results revealed that motor imitation of the perceived action significantly increased the time spent perceiving the hand. Three control experiments showed that these effects were not due to a generic involvement of focused attention (Experiment 2 and 3, to a verbal description of the performed action (Experiment 3 or to the execution of an unrelated movement of the hand (Experiment 4. Although an intrinsic connection between action execution and attention cannot be excluded with certainty, and the boundary between action imitation and unrelated action execution may vary along various degrees of similarity, on the whole, the present results seem to suggest, at least on a preliminary basis, that action imitation do play a relevant role in the perception of action. We discuss these findings in the frame of current theories concerning the relation between perception and action.

  5. The future of binocular rivalry research: reaching through a window on consciousness

    NARCIS (Netherlands)

    Klink, P. Christiaan; Wezel, van Richard J.A.; Ee, van Raymond; Miller, Steven M.

    2013-01-01

    Binocular rivalry is often considered an experimental window on the neural processes of consciousness. We propose three distinct approaches to exploit this window. First, one may look through the window, using binocular rivalry as a passive tool to dissociate unaltered sensory input from wavering pe

  6. Retinotopic and non-retinotopic stimulus encoding in binocular rivalry and the involvement of feedback

    NARCIS (Netherlands)

    van Boxtel, J.J.A.; Alais, D.; van Ee, R.

    2008-01-01

    Adaptation is one of the key constituents of the perceptual alternation process during binocular rivalry, as it has been shown that preadapting one of the rivaling pairs before rivalry onset biases perception away from the adapted stimulus during rivalry. We investigated the influence of retinotopic

  7. Temporal patterns of saccadic eye movements predict individual variation in alternation rate during binocular rivalry

    OpenAIRE

    Hancock, Sarah; Gareze, Lynn; Findlay, John M; Andrews, Timothy J.

    2012-01-01

    Interindividual variation has been shown in the rates at which subjects alternate in perception during viewing of binocular rivalry and other ambiguous figures. A similar pattern of interindividual variation is evident in the rate of eye movements. The aim of this study was to determine whether individual differences in the rate of binocular rivalry predict individual differences in the rate of eye movements. First, participants reported changes in perception during contour rivalry. We found ...

  8. Motion dominance in binocular rivalry depends on extraretinal motions.

    Science.gov (United States)

    Nakayama, Ryohei; Motoyoshi, Isamu; Sato, Takao

    2016-01-01

    In binocular rivalry, moving stimulus is dominant over stationary stimulus. This is called motion dominance. The motion here is usually a motion defined on the retina (retinal motion). However, motion can be defined in several different coordinates. It can be defined with respect to objects in the background (object-based motion) or to observers' head or body (spatiotopic motion), as well as to the retinal coordinate. In this study, we examined the role of motions defined by these three coordinates. A dichoptic pair of gratings was presented to create a binocular rivalry, one of which was moving and the other stationary. A fixation point and a reference background were either moving with the grating or stationary, depending on the condition. Different combinations of the three types of motions were created by having the observer track the fixation point or the background when they are moving. It was found that the retinal motion does not necessarily yield motion dominance, and that the motion dominance is determined by the combination of motions defined by different coordinate systems. PMID:26943347

  9. Natural Tendency towards Beauty in Humans: Evidence from Binocular Rivalry.

    Science.gov (United States)

    Mo, Ce; Xia, Tiansheng; Qin, Kaixin; Mo, Lei

    2016-01-01

    Although human preference for beauty is common and compelling in daily life, it remains unknown whether such preference is essentially subserved by social cognitive demands or natural tendency towards beauty encoded in the human mind intrinsically. Here we demonstrate experimentally that humans automatically exhibit preference for visual and moral beauty without explicit cognitive efforts. Using a binocular rivalry paradigm, we identified enhanced gender-independent perceptual dominance for physically attractive persons, and the results suggested universal preference for visual beauty based on perceivable forms. Moreover, we also identified perceptual dominance enhancement for characters associated with virtuous descriptions after controlling for facial attractiveness and vigilance-related attention effects, which suggested a similar implicit preference for moral beauty conveyed in prosocial behaviours. Our findings show that behavioural preference for beauty is driven by an inherent natural tendency towards beauty in humans rather than explicit social cognitive processes. PMID:26930202

  10. Natural Tendency towards Beauty in Humans: Evidence from Binocular Rivalry.

    Directory of Open Access Journals (Sweden)

    Ce Mo

    Full Text Available Although human preference for beauty is common and compelling in daily life, it remains unknown whether such preference is essentially subserved by social cognitive demands or natural tendency towards beauty encoded in the human mind intrinsically. Here we demonstrate experimentally that humans automatically exhibit preference for visual and moral beauty without explicit cognitive efforts. Using a binocular rivalry paradigm, we identified enhanced gender-independent perceptual dominance for physically attractive persons, and the results suggested universal preference for visual beauty based on perceivable forms. Moreover, we also identified perceptual dominance enhancement for characters associated with virtuous descriptions after controlling for facial attractiveness and vigilance-related attention effects, which suggested a similar implicit preference for moral beauty conveyed in prosocial behaviours. Our findings show that behavioural preference for beauty is driven by an inherent natural tendency towards beauty in humans rather than explicit social cognitive processes.

  11. Natural Tendency towards Beauty in Humans: Evidence from Binocular Rivalry

    Science.gov (United States)

    Mo, Lei

    2016-01-01

    Although human preference for beauty is common and compelling in daily life, it remains unknown whether such preference is essentially subserved by social cognitive demands or natural tendency towards beauty encoded in the human mind intrinsically. Here we demonstrate experimentally that humans automatically exhibit preference for visual and moral beauty without explicit cognitive efforts. Using a binocular rivalry paradigm, we identified enhanced gender-independent perceptual dominance for physically attractive persons, and the results suggested universal preference for visual beauty based on perceivable forms. Moreover, we also identified perceptual dominance enhancement for characters associated with virtuous descriptions after controlling for facial attractiveness and vigilance-related attention effects, which suggested a similar implicit preference for moral beauty conveyed in prosocial behaviours. Our findings show that behavioural preference for beauty is driven by an inherent natural tendency towards beauty in humans rather than explicit social cognitive processes. PMID:26930202

  12. Travelling waves of activity in primary visual cortex during binocular rivalry

    OpenAIRE

    Lee, Sang-Hun; Blake, Randolph; Heeger, David J.

    2004-01-01

    When the two eyes view large dissimilar patterns that induce binocular rivalry, alternating waves of visibility are experienced, as one pattern sweeps the other out of conscious awareness. Here we show tight linkage between dynamics of perceptual waves during rivalry and neural events in human primary visual cortex (V1).

  13. Influence of retinal image shifts and extra-retinal eye movement signals on binocular rivalry alternations

    OpenAIRE

    Kalisvaart, Joke P.; Jeroen Goossens

    2013-01-01

    Previous studies have indicated that saccadic eye movements correlate positively with perceptual alternations in binocular rivalry, presumably because the foveal image changes resulting from saccades, rather than the eye movement themselves, cause switches in awareness. Recently, however, we found evidence that retinal image shifts elicit so-called onset rivalry and not percept switches as such. These findings raise the interesting question whether onset rivalry may account for correlations b...

  14. Stereopsis and binocular rivalry are based on perceived rather than physical orientations

    OpenAIRE

    Chopin, Adrien; Mamassian, Pascal; Blake, Randolph

    2012-01-01

    Binocular rivalry is an intriguing phenomenon: when different images are displayed to the two eyes, perception alternates between these two images. What determines whether two monocular images engage in fusion or in rivalry: the physical difference between these images or the difference between the percepts resulting from the images? We investigated that question by measuring the interocular difference of grid orientation needed to produce a transition from fusion to rivalry and by changing t...

  15. General Validity of Levelt's Propositions Reveals Common Computational Mechanisms for Visual Rivalry

    OpenAIRE

    P Christiaan Klink; Raymond van Ee; van Wezel, Richard J. A.

    2008-01-01

    The mechanisms underlying conscious visual perception are often studied with either binocular rivalry or perceptual rivalry stimuli. Despite existing research into both types of rivalry, it remains unclear to what extent their underlying mechanisms involve common computational rules. Computational models of binocular rivalry mechanisms are generally tested against Levelt's four propositions, describing the psychophysical relation between stimulus strength and alternation dynamics in binocular...

  16. Difference in the binocular rivalry rate between depressive episodes and remission.

    Science.gov (United States)

    Jia, Ting; Ye, Xing; Wei, Qiang; Xie, Wen; Cai, Chunlan; Mu, Jingjing; Dong, Yi; Hu, Panpan; Hu, Xinglong; Tian, Yanghua; Wang, Kai

    2015-11-01

    Binocular rivalry refers to a phenomenon in which, when different images are presented to each eye simultaneously, perception alternates spontaneously between monocular views rather than being a superposition of the two images. Recently, the involvement of serotonin systems has been reported to be related to the phenomenon. There is abundant evidence for abnormalities of the serotonin systems in depression and the antidepressants that enhance 5-HT transmission, which in turn improves mood and behavior. However, the available data with respect to rivalry rates in depression are less clear. Therefore, we aimed to explore whether perceptual rivalry was affected by a dysfunctional serotonin system in patients with depression and whether there was a rivalry rate difference between episode and remission states in depression patients. Twenty-eight patients with depression and 30 healthy controls were recruited in the study. We assessed the rivalry rate and the 17-item Hamilton Depression Rating Scale (HAMD) in patients with depression during clinical episode and remission states. The results suggested that alternation rates for patients during episodes were significantly slower than during remission and than in healthy controls. Also, alternation rates for patients during remission were slower than in healthy controls. These results may provide further clues to serotonergic neural systems contributing to the dynamics of perception rivalry and may foster enlightenment regarding the field of binocular rivalry in psychiatric disorders other than bipolar disorder. PMID:26247392

  17. Congruent tactile stimulation reduces the strength of visual suppression during binocular rivalry

    OpenAIRE

    Claudia Lunghi; David Alais

    2015-01-01

    Presenting different images to each eye triggers ‘binocular rivalry’ in which one image is visible and the other suppressed, with the visible image alternating every second or so. We previously showed that binocular rivalry between cross-oriented gratings is altered when the fingertip explores a grooved stimulus aligned with one of the rivaling gratings: the matching visual grating's dominance duration was lengthened and its suppression duration shortened. In a more robust test, we here measu...

  18. General validity of Levelt's propositions reveals common computational mechanisms for visual rivalry

    NARCIS (Netherlands)

    Klink, P.C.; van Ee, R.; van Wezel, R.J.A.

    2008-01-01

    The mechanisms underlying conscious visual perception are often studied with either binocular rivalry or perceptual rivalry stimuli. Despite existing research into both types of rivalry, it remains unclear to what extent their underlying mechanisms involve common computational rules. Computational m

  19. Training of binocular rivalry suppression suggests stimulus-specific plasticity in monocular and binocular visual areas.

    Science.gov (United States)

    Vergeer, Mark; Wagemans, Johan; van Ee, Raymond

    2016-01-01

    The plasticity of the human brain, as shown in perceptual learning, is generally reflected by improved task performance after training. Here, we show that perceptual suppression can be increased through training. In the first experiment, binocular rivalry suppression of a specific orientation was trained, leading to a relative reduction in sensitivity to the trained orientation. In a second experiment, two orthogonal orientations were suppressed in alternating training blocks, in the left and right eye, respectively. This double-training procedure lead to reduced sensitivity for the orientation that was suppression-trained in each specific eye, implying that training of feature suppression is specific for the eye in which the oriented grating was presented during training. Results of a control experiment indicate that the obtained effects are indeed due to suppression during training, instead of being merely due to the repetitive presentation of the oriented gratings. Visual plasticity is essential for a person's visual development. The finding that plasticity can result in increased perceptual suppression reported here may prove to be significant in understanding human visual development. It emphasizes that for stable vision, not only the enhancement of relevant signals is crucial, but also the reliable and stable suppression of (task) irrelevant signals. PMID:27160838

  20. Congruent tactile stimulation reduces the strength of visual suppression during binocular rivalry.

    Science.gov (United States)

    Lunghi, Claudia; Alais, David

    2015-01-01

    Presenting different images to each eye triggers 'binocular rivalry' in which one image is visible and the other suppressed, with the visible image alternating every second or so. We previously showed that binocular rivalry between cross-oriented gratings is altered when the fingertip explores a grooved stimulus aligned with one of the rivaling gratings: the matching visual grating's dominance duration was lengthened and its suppression duration shortened. In a more robust test, we here measure visual contrast sensitivity during rivalry dominance and suppression, with and without exploration of the grooved surface, to determine if rivalry suppression strength is modulated by touch. We find that a visual grating undergoes 45% less suppression when observers touch an aligned grating, compared to a cross-oriented one. Touching an aligned grating also improved visual detection thresholds for the 'invisible' suppressed grating by 2.4 dB, relative to a vision-only condition. These results show that congruent haptic stimulation prevents a visual stimulus from becoming deeply suppressed in binocular rivalry. Moreover, because congruent touch acted on the phenomenally invisible grating, this visuo-haptic interaction must precede awareness and likely occurs early in visual processing. PMID:25797534

  1. The Influence of Anxiety on the Initial Selection of Emotional Faces Presented in Binocular Rivalry

    Science.gov (United States)

    Gray, Katie L. H.; Adams, Wendy J.; Garner, Matthew

    2009-01-01

    Neurocognitive theories of anxiety predict that threat-related information can be evaluated before attentional selection, and can influence behaviour differentially in high anxious compared to low anxious individuals. We investigate this further by presenting emotional and neutral faces in an adapted binocular rivalry paradigm. We show that the…

  2. The impact of stimulus complexity and frequency swapping on stabilization of binocular rivalry

    DEFF Research Database (Denmark)

    Sandberg, Kristian; Bahrami, Bahador; Lindeløv, Jonas Kristoffer;

    2011-01-01

    Binocular rivalry occurs when an image is presented to one eye while at the same time another, incongruent, image is presented to the other eye in the corresponding retinotopic location and conscious perception alternates spontaneously between the two monocular views. If a short blank period is...

  3. A low-dimensional model of binocular rivalry using winnerless competition

    Science.gov (United States)

    Ashwin, Peter; Lavric, Aureliu

    2010-05-01

    We discuss a novel minimal model for binocular rivalry (and more generally perceptual dominance) effects. The model has only three state variables, but nonetheless exhibits a wide range of input and noise-dependent switching. The model has two reciprocally inhibiting input variables that represent perceptual processes active during the recognition of one of the two possible states and a third variable that represents the perceived output. Sensory inputs only affect the input variables. We observe, for rivalry-inducing inputs, the appearance of winnerless competition in the perceptual system. This gives rise to a behaviour that conforms to well-known principles describing binocular rivalry (the Levelt propositions, in particular proposition IV: monotonic response of residence time as a function of image contrast) down to very low levels of stimulus intensity.

  4. Image-based grouping during binocular rivalry is dictated by eye-of-origin.

    Directory of Open Access Journals (Sweden)

    Sjoerd M Stuit

    Full Text Available Prolonged viewing of dichoptically presented images with different content results in perceptual alternations known as binocular rivalry. This phenomenon is thought to be the result of competition at a local level, where local rivalry zones interact to give rise to a single, global dominant percept. Certain perceived combinations that result from this local competition are known to last longer than others, which is referred to as grouping during binocular rivalry. In recent years, the phenomenon has been suggested to be the result of competition at both eye- and image-based processing levels, although the exact contribution from each level remains elusive. Here we use a paradigm designed specifically to quantify the contribution of eye- and image-based processing to grouping during rivalry. In this paradigm we used sine-wave gratings as well as upright and inverted faces, with and without binocular disparity-based occlusion. These stimuli and conditions were used because they are known to result in processing at different stages throughout the visual processing hierarchy. Specifically, more complex images were included in order to maximize the potential contribution of image-based grouping. In spite of this, our results show that increasing image complexity did not lead to an increase in the contribution of image-based processing to grouping during rivalry. In fact, the results show that grouping was primarily affected by the eye-of-origin of the image parts, irrespective of stimulus type. We suggest that image content affects grouping during binocular rivalry at low-level processing stages, where it is intertwined with eye-of-origin information.

  5. 'Proto-rivalry': how the binocular brain identifies gloss.

    Science.gov (United States)

    Muryy, Alexander A; Fleming, Roland W; Welchman, Andrew E

    2016-05-11

    Visually identifying glossy surfaces can be crucial for survival (e.g. ice patches on a road), yet estimating gloss is computationally challenging for both human and machine vision. Here, we demonstrate that human gloss perception exploits some surprisingly simple binocular fusion signals, which are likely available early in the visual cortex. In particular, we show that the unusual disparity gradients and vertical offsets produced by reflections create distinctive 'proto-rivalrous' (barely fusible) image regions that are a critical indicator of gloss. We find that manipulating the gradients and vertical components of binocular disparities yields predictable changes in material appearance. Removing or occluding proto-rivalrous signals makes surfaces look matte, while artificially adding such signals to images makes them appear glossy. This suggests that the human visual system has internalized the idiosyncratic binocular fusion characteristics of glossy surfaces, providing a straightforward means of estimating surface attributes using low-level image signals. PMID:27170713

  6. MEG phase follows conscious perception during binocular rivalry induced by visual stream segregation

    OpenAIRE

    Petrovic, Sanja; Srinivasan, Ramesh

    2005-01-01

    We have investigated an unusual form of binocular rivalry between two images that are flickered one to each eye, but are never presented simultaneously to the observer. The images are presented in alternation, with a brief dark period between the images. When the flicker frequency was below 5 Hz, the subjects primarily experienced a unitary flicker that alternated between the two images. When the flicker frequency was above 5 Hz, the subjects primarily experienced two single-image flickers th...

  7. Touch interacts with vision during binocular rivalry with a tight orientation tuning.

    Directory of Open Access Journals (Sweden)

    Claudia Lunghi

    Full Text Available Multisensory integration is a common feature of the mammalian brain that allows it to deal more efficiently with the ambiguity of sensory input by combining complementary signals from several sensory sources. Growing evidence suggests that multisensory interactions can occur as early as primary sensory cortices. Here we present incompatible visual signals (orthogonal gratings to each eye to create visual competition between monocular inputs in primary visual cortex where binocular combination would normally take place. The incompatibility prevents binocular fusion and triggers an ambiguous perceptual response in which the two images are perceived one at a time in an irregular alternation. One key function of multisensory integration is to minimize perceptual ambiguity by exploiting cross-sensory congruence. We show that a haptic signal matching one of the visual alternatives helps disambiguate visual perception during binocular rivalry by both prolonging the dominance period of the congruent visual stimulus and by shortening its suppression period. Importantly, this interaction is strictly tuned for orientation, with a mismatch as small as 7.5° between visual and haptic orientations sufficient to annul the interaction. These results indicate important conclusions: first, that vision and touch interact at early levels of visual processing where interocular conflicts are first detected and orientation tunings are narrow, and second, that haptic input can influence visual signals outside of visual awareness, bringing a stimulus made invisible by binocular rivalry suppression back to awareness sooner than would occur without congruent haptic input.

  8. Surface area of early visual cortex predicts individual speed of traveling waves during binocular rivalry.

    Science.gov (United States)

    Genç, Erhan; Bergmann, Johanna; Singer, Wolf; Kohler, Axel

    2015-06-01

    Binocular rivalry ensues when different images are presented to the 2 eyes with conscious perception alternating between the possible interpretations. For large rivalry displays, perceptual transitions are initiated at one location and spread to other parts of the visual field, a phenomenon termed "traveling wave." Previous studies investigated the underlying neural mechanisms of the traveling wave and surmised that primary visual cortex might play an important role. We used magnetic resonance imaging and behavioral measures in humans to explore how interindividual differences in observers' subjective experience of the wave are related to anatomical characteristics of cortical regions. We measured wave speed in participants and confirmed the long-term stability of the individual values. Retinotopic mapping was employed to delineate borders of visual areas V1-V3 in order to determine surface area and cortical thickness in those regions. Only the surface areas of V1 and V2, but not V3 showed a correlation with wave speed. For individuals with larger V1/V2 area, the traveling wave needed longer to spread across the same distance in visual space. Our results highlight the role of early visual areas in mediating binocular rivalry and suggest possible mechanisms for the correlation between surface area and the traveling waves. PMID:24334918

  9. Very few exclusive percepts for contrast-modulated stimuli during binocular rivalry.

    Science.gov (United States)

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

    2016-04-01

    Binocular rivalry properties for contrast-modulated (CM) gratings were examined to gain insight into their locus of processing. Two orthogonally orientated gratings were presented, one to each eye. Perceptual change rates, proportions of exclusivity and mixed percepts, and mean durations were calculated. Stimuli were noiseless luminance-defined (L), luminance-modulated noise (LM) and contrast-modulated noise (CM) gratings with sizes of 1, 2 and 4deg and spatial frequencies of 4, 2 and 1c/deg, respectively. For the LM and CM gratings, binary noise was fully correlated between eyes. Maximum producible modulations were used (1.0 for CM, 0.78 for LM and 0.98 for L stimuli). In a control experiment, contrasts of LM gratings were reduced until the multiples over detection threshold were similar to those of CM stimuli. Trial durations of 120s were analyzed. Exclusive visibility decreased with increasing stimulus size regardless of the stimulus type. Even with visibilities at similar multiples above detection threshold, significantly lower proportions of exclusive percepts and perceptual changes were found for CM, compared to LM gratings. The results obtained with dichoptically presented orthogonal CM gratings are significantly different from those obtained for orthogonal gratings presented to one eye. CM stimuli therefore do engage in binocular rivalry but with different characteristics to those found for LM stimuli. These results suggest that CM stimuli are processed by a mechanism that promotes binocular combination rather than rivalry, and therefore may involve cells in a higher visual area than those that initially process LM information. PMID:26827700

  10. A binocular rivalry study of motion perception in the human brain.

    Science.gov (United States)

    Moutoussis, K; Keliris, G; Kourtzi, Z; Logothetis, N

    2005-08-01

    The relationship between brain activity and conscious visual experience is central to our understanding of the neural mechanisms underlying perception. Binocular rivalry, where monocular stimuli compete for perceptual dominance, has been previously used to dissociate the constant stimulus from the varying percept. We report here fMRI results from humans experiencing binocular rivalry under a dichoptic stimulation paradigm that consisted of two drifting random dot patterns with different motion coherence. Each pattern had also a different color, which both enhanced rivalry and was used for reporting which of the two patterns was visible at each time. As the perception of the subjects alternated between coherent motion and motion noise, we examined the effect that these alternations had on the strength of the MR signal throughout the brain. Our results demonstrate that motion perception is able to modulate the activity of several of the visual areas which are known to be involved in motion processing. More specifically, in addition to area V5 which showed the strongest modulation, a higher activity during the perception of motion than during the perception of noise was also clearly observed in areas V3A and LOC, and less so in area V3. In previous studies, these areas had been selectively activated by motion stimuli but whether their activity reflects motion perception or not remained unclear; here we show that they are involved in motion perception as well. The present findings therefore suggest a lack of a clear distinction between 'processing' versus 'perceptual' areas in the brain, but rather that the areas involved in the processing of a specific visual attribute are also part of the neuronal network that is collectively responsible for its perceptual representation. PMID:15924938

  11. Rivalries

    OpenAIRE

    Evan Osborne

    2008-01-01

    Rivalries are a key aspect of sports, but one with few counterparts elsewhere in economic theory. In this paper rivalries are modeled as a habitual good, and complementary in fan utility with other trade between residents of team locations. Some implications for optimal team investment in rivalry capital, for league investment in competitive balance, and for the fundamental differences between rivalries in team and individual sports are derived.

  12. Reinforcement of perceptual inference: reward and punishment alter conscious visual perception during binocular rivalry

    Directory of Open Access Journals (Sweden)

    Gregor eWilbertz

    2014-12-01

    Full Text Available Perception is an inferential process, which becomes immediately evident when sensory information is conflicting or ambiguous and thus allows for more than one perceptual interpretation. Thinking the idea of perception as inference through to the end results in a blurring of boundaries between perception and action selection, as perceptual inference implies the construction of a percept as an active process. Here we therefore wondered whether perception shares a key characteristic of action selection, namely that it is shaped by reinforcement learning. In two behavioral experiments, we used binocular rivalry to examine whether perceptual inference can be influenced by the association of perceptual outcomes with reward or punishment, respectively, in analogy to instrumental conditioning. Binocular rivalry was evoked by two orthogonal grating stimuli presented to the two eyes, resulting in perceptual alternations between the two gratings. Perception was tracked indirectly and objectively through a target detection task, which allowed us to preclude potential reporting biases. Monetary rewards or punishments were given repeatedly during perception of only one of the two rivalling stimuli. We found an increase in dominance durations for the percept associated with reward, relative to the non-rewarded percept. In contrast, punishment led to an increase of the non-punished compared to a relative decrease of the punished percept. Our results show that perception shares key characteristics with action selection, in that it is influenced by reward and punishment in opposite directions, thus narrowing the gap between the conceptually separated domains of perception and action selection. We conclude that perceptual inference is an adaptive process that is shaped by its consequences.

  13. The effects of noise on binocular rivalry waves: a stochastic neural field model

    International Nuclear Information System (INIS)

    We analyze the effects of extrinsic noise on traveling waves of visual perception in a competitive neural field model of binocular rivalry. The model consists of two one-dimensional excitatory neural fields, whose activity variables represent the responses to left-eye and right-eye stimuli, respectively. The two networks mutually inhibit each other, and slow adaptation is incorporated into the model by taking the network connections to exhibit synaptic depression. We first show how, in the absence of any noise, the system supports a propagating composite wave consisting of an invading activity front in one network co-moving with a retreating front in the other network. Using a separation of time scales and perturbation methods previously developed for stochastic reaction–diffusion equations, we then show how extrinsic noise in the activity variables leads to a diffusive-like displacement (wandering) of the composite wave from its uniformly translating position at long time scales, and fluctuations in the wave profile around its instantaneous position at short time scales. We use our analysis to calculate the first-passage-time distribution for a stochastic rivalry wave to travel a fixed distance, which we find to be given by an inverse Gaussian. Finally, we investigate the effects of noise in the depression variables, which under an adiabatic approximation lead to quenched disorder in the neural fields during propagation of a wave. (paper)

  14. The effects of noise on binocular rivalry waves: a stochastic neural field model

    KAUST Repository

    Webber, Matthew A

    2013-03-12

    We analyze the effects of extrinsic noise on traveling waves of visual perception in a competitive neural field model of binocular rivalry. The model consists of two one-dimensional excitatory neural fields, whose activity variables represent the responses to left-eye and right-eye stimuli, respectively. The two networks mutually inhibit each other, and slow adaptation is incorporated into the model by taking the network connections to exhibit synaptic depression. We first show how, in the absence of any noise, the system supports a propagating composite wave consisting of an invading activity front in one network co-moving with a retreating front in the other network. Using a separation of time scales and perturbation methods previously developed for stochastic reaction-diffusion equations, we then show how extrinsic noise in the activity variables leads to a diffusive-like displacement (wandering) of the composite wave from its uniformly translating position at long time scales, and fluctuations in the wave profile around its instantaneous position at short time scales. We use our analysis to calculate the first-passage-time distribution for a stochastic rivalry wave to travel a fixed distance, which we find to be given by an inverse Gaussian. Finally, we investigate the effects of noise in the depression variables, which under an adiabatic approximation lead to quenched disorder in the neural fields during propagation of a wave. © 2013 IOP Publishing Ltd and SISSA Medialab srl.

  15. General validity of Levelt's propositions reveals common computational mechanisms for visual rivalry.

    Directory of Open Access Journals (Sweden)

    P Christiaan Klink

    Full Text Available The mechanisms underlying conscious visual perception are often studied with either binocular rivalry or perceptual rivalry stimuli. Despite existing research into both types of rivalry, it remains unclear to what extent their underlying mechanisms involve common computational rules. Computational models of binocular rivalry mechanisms are generally tested against Levelt's four propositions, describing the psychophysical relation between stimulus strength and alternation dynamics in binocular rivalry. Here we use a bistable rotating structure-from-motion sphere, a generally studied form of perceptual rivalry, to demonstrate that Levelt's propositions also apply to the alternation dynamics of perceptual rivalry. Importantly, these findings suggest that bistability in structure-from-motion results from active cross-inhibition between neural populations with computational principles similar to those present in binocular rivalry. Thus, although the neural input to the computational mechanism of rivalry may stem from different cortical neurons and different cognitive levels the computational principles just prior to the production of visual awareness appear to be common to the two types of rivalry.

  16. Cortical microcircuit dynamics mediating Binocular Rivalry: The role of adaptation in inhibition

    Directory of Open Access Journals (Sweden)

    Panagiota eTheodoni

    2011-11-01

    Full Text Available Perceptual bistability arises when two conflicting interpretations of an ambiguous stimulus or images in binocular rivalry (BR compete for perceptual dominance. From a computational point of view competition models based on cross-inhibition and adaptation have shown that noise is a crucial force for rivalry and operates in balance with adaptation in order to explain the observed alternations in perception. In particular, noise-driven transitions and adaptation-driven oscillations define two dynamical regimes and the system operates near its boundary. In order to gain insights into the microcircuit dynamics mediating spontaneous perceptual alternations we used a reduced recurrent attractor-based biophysically realistic spiking network well known for working memory, attention and decision-making, where a spike-frequency adaptation mechanism is implemented to account for perceptual bistability. We, thus, derived a consistently reduced four-variable population rate model using mean-field techniques and tested it on BR data collected from human subjects. Our model accounts for experimental data parameters such as time dominance, coefficient of variation and gamma distribution. In addition, we show that our model also operates on the boundary between noise and adaptation and agrees with Levelt’s second revised and fourth propositions. These results show for the first time that a consistent reduction of a biophysically realistic spiking network of integrate and fire neurons with spike frequency adaptation could account for BR. Moreover, we demonstrate that BR can be explained only through the dynamics of the competing neuronal pools, without taking into account the adaptation of inhibitory interneurons..However, adaptation of interneurons affects the optimal parametric space of the system, by decreasing the overall adaptation necessary for the bifurcation to occur.

  17. Why is binocular rivalry uncommon? Discrepant monocular images in the real world

    Directory of Open Access Journals (Sweden)

    Derek Henry Arnold

    2011-10-01

    Full Text Available When different images project to corresponding points in the two eyes they can instigate a phenomenon called binocular rivalry (BR, wherein each image seems to intermittently disappear such that only one of the two images is seen at a time. Cautious readers may have noted an important caveat in the opening sentence – this situation can instigate BR, but usually it doesn’t. Unmatched monocular images are frequently encountered in daily life due to either differential occlusions of the two eyes or because of selective obstructions of just one eye, but this does not tend to induce BR. Here I will explore the reasons for this and discuss implications for BR in general. It will be argued that BR is resolved in favour of the instantaneously stronger neural signal, and that this process is driven by an adaptation that enhances the visibility of distant fixated objects over that of more proximate obstructions of an eye. Accordingly, BR would reflect the dynamics of an inherently visual operation that usually deals with real-world constraints.

  18. Hearing (Rivaling Lips and Seeing Voices: How Audiovisual Interactions Modulate Perceptual Stabilization in Binocular Rivalry

    Directory of Open Access Journals (Sweden)

    Manuel eVidal

    2014-09-01

    Full Text Available In binocular rivalry (BR, sensory input remains the same yet subjective experience fluctuates irremediably between two mutually exclusive representations. We investigated the perceptual stabilization effect of an additional sound on the BR dynamics using speech stimuli known to involve robust audiovisual (AV interactions at several cortical levels. Subjects sensitive to the McGurk effect were presented looping videos of rivaling faces uttering /aba/ and /aga/ respectively, while synchronously hearing the voice /aba/. They reported continuously the dominant percept, either observing passively or trying actively to promote one of the faces. The few studies that investigated the influence of information from an external modality on perceptual competition reported results that seem at first sight inconsistent. Since these differences could stem from how well the modalities matched, we addressed this by comparing two levels of AV congruence: real (/aba/ viseme vs. illusory (/aga/ viseme producing the /ada/ McGurk fusion. First, adding the voice /aba/ stabilized both real and illusory congruent lips percept. Second, real congruence of the added voice improved volitional control whereas illusory congruence did not, suggesting a graded contribution to the top-down sensitivity control of selective attention. In conclusion, a congruent sound enhanced considerably attentional control over the perceptual outcome selection; however, differences between passive stabilization and active control according to AV congruency suggest these are governed by two distinct mechanisms. Based on existing theoretical models of BR, selective attention and AV interaction in speech perception, we provide a general interpretation of our findings.

  19. Callosal connections of primary visual cortex predict the spatial spreading of binocular rivalry across the visual hemifields

    Directory of Open Access Journals (Sweden)

    Erhan eGenc

    2011-12-01

    Full Text Available In binocular rivalry, presentation of different images to the separate eyes leads to conscious perception alternating between the two possible interpretations every few seconds. During perceptual transitions, a stimulus emerging into dominance can spread in a wave-like manner across the visual field. These traveling waves of rivalry dominance have been successfully related to the cortical magnification properties and functional activity of early visual areas, including the primary visual cortex (V1. Curiously however, these traveling waves undergo a delay when passing from one hemifield to another. In the current study, we used diffusion tensor imaging (DTI to investigate whether the strength of interhemispheric connections between the left and right visual cortex might be related to the delay of traveling waves across hemifields. We measured the delay in traveling-wave times (ΔTWT in nineteen participants and repeated this test 6 weeks later to evaluate the reliability of our behavioral measures. We found large interindividual variability but also good test-retest reliability for individual measures of ΔTWT. Using DTI in connection with fiber tractography, we identified parts of the corpus callosum connecting functionally defined visual areas V1-V3. We found that individual differences in ΔTWT was reliably predicted by the diffusion properties of transcallosal fibers connecting left and right V1, but observed no such effect for neighboring transcallosal visual fibers connecting V2 and V3. Our results demonstrate that the anatomical characteristics of topographically specific transcallosal connections predict the individual delay of interhemispheric traveling waves, providing further evidence that V1 is an important site for neural processes underlying binocular rivalry.

  20. Duality in binocular rivalry: distinct sensitivity of percept sequence and percept duration to imbalance between monocular stimuli.

    Directory of Open Access Journals (Sweden)

    Chen Song

    Full Text Available BACKGROUND: Visual perception is usually stable and accurate. However, when the two eyes are simultaneously presented with conflicting stimuli, perception falls into a sequence of spontaneous alternations, switching between one stimulus and the other every few seconds. Known as binocular rivalry, this visual illusion decouples subjective experience from physical stimulation and provides a unique opportunity to study the neural correlates of consciousness. The temporal properties of this alternating perception have been intensively investigated for decades, yet the relationship between two fundamental properties - the sequence of percepts and the duration of each percept - remains largely unexplored. METHODOLOGY/PRINCIPAL FINDINGS: Here we examine the relationship between the percept sequence and the percept duration by quantifying their sensitivity to the strength imbalance between two monocular stimuli. We found that the percept sequence is far more susceptible to the stimulus imbalance than does the percept duration. The percept sequence always begins with the stronger stimulus, even when the stimulus imbalance is too weak to cause a significant bias in the percept duration. Therefore, introducing a small stimulus imbalance affects the percept sequence, whereas increasing the imbalance affects the percept duration, but not vice versa. To investigate why the percept sequence is so vulnerable to the stimulus imbalance, we further measured the interval between the stimulus onset and the first percept, during which subjects experienced the fusion of two monocular stimuli. We found that this interval is dramatically shortened with increased stimulus imbalance. CONCLUSIONS/SIGNIFICANCE: Our study shows that in binocular rivalry, the strength imblanace between monocular stimuli has a much greater impact on the percept sequence than on the percept duration, and increasing this imbalance can accelerate the process responsible for the percept sequence.

  1. Neuromagnetic evidence that the right fusiform face area is essential for human face awareness: An intermittent binocular rivalry study.

    Science.gov (United States)

    Kume, Yuko; Maekawa, Toshihiko; Urakawa, Tomokazu; Hironaga, Naruhito; Ogata, Katsuya; Shigyo, Maki; Tobimatsu, Shozo

    2016-08-01

    When and where the awareness of faces is consciously initiated is unclear. We used magnetoencephalography to probe the brain responses associated with face awareness under intermittent pseudo-rivalry (PR) and binocular rivalry (BR) conditions. The stimuli comprised three pictures: a human face, a monkey face and a house. In the PR condition, we detected the M130 component, which has been minimally characterized in previous research. We obtained a clear recording of the M170 component in the fusiform face area (FFA), and found that this component had an earlier response time to faces compared with other objects. The M170 occurred predominantly in the right hemisphere in both conditions. In the BR condition, the amplitude of the M130 significantly increased in the right hemisphere irrespective of the physical characteristics of the visual stimuli. Conversely, we did not detect the M170 when the face image was suppressed in the BR condition, although this component was clearly present when awareness for the face was initiated. We also found a significant difference in the latency of the M170 (human

  2. The Quantum-Classical and Mind-Brain Linkages: The Quantum Zeno Effect in Binocular Rivalry

    CERN Document Server

    Stapp, Henry P

    2007-01-01

    A quantum mechanical theory of the relationship between perceptions and brain dynamics based on von Neumann's theory of measurments is applied to a recent quantum theoretical treatment of binocular rivaly that makes essential use of the quantum Zeno effect to give good fits to the complex available empirical data. The often-made claim that decoherence effects in the warm, wet, noisy brain must eliminate quantum effects at the macroscopic scale pertaining to perceptions is examined, and it is argued, on the basis of fundamental principles. that the usual decoherence effects will not upset the quantum Zeno effect that is being exploited in the cited work.

  3. Perceptual Rivalry: Reflexes Reveal the Gradual Nature of Visual Awareness

    OpenAIRE

    Marnix Naber; Stefan Frässle; Wolfgang Einhäuser

    2011-01-01

    Rivalry is a common tool to probe visual awareness: a constant physical stimulus evokes multiple, distinct perceptual interpretations ("percepts") that alternate over time. Percepts are typically described as mutually exclusive, suggesting that a discrete (all-or-none) process underlies changes in visual awareness. Here we follow two strategies to address whether rivalry is an all-or-none process: first, we introduce two reflexes as objective measures of rivalry, pupil dilation and optokineti...

  4. Temporal Analysis of Image-Rivalry Suppression

    OpenAIRE

    Rishi Bhardwaj; Robert P. O'shea

    2012-01-01

    During binocular rivalry, perception alternates between two different images presented one to each eye. At any moment, one image is visible, dominant, while the other is invisible, suppressed. Alternations in perception during rivalry could involve competition between eyes, eye-rivalry, or between images, image-rivalry, or both. We measured response criteria, sensitivities, and thresholds to brief contrast increments to one of the rival stimuli in conventional rivalry displays and in a displa...

  5. Unmixing binocular signals

    Directory of Open Access Journals (Sweden)

    Sidney R Lehky

    2011-08-01

    Full Text Available Incompatible images presented to the two eyes lead to perceptual oscillations in which one image at a time is visible. Early models portrayed this binocular rivalry as involving reciprocal inhibition between monocular representations of images, occurring at an early visual stage prior to binocular mixing. However, psychophysical experiments found conditions where rivalry could also occur at a higher, more abstract level of representation. In those cases, the rivalry was between image representations dissociated from eye-of-origin information, rather than between monocular representations from the two eyes. Moreover, neurophysiological recordings found the strongest rivalry correlate in inferotemporal cortex, a high-level, predominantly binocular visual area involved in object recognition, rather than early visual structures. An unresolved issue is how can the separate identities of the two images be maintained after binocular mixing in order for rivalry to be possible at higher levels? Here we demonstrate that after the two images are mixed, they can be unmixed at any subsequent stage using a physiologically plausible nonlinear signal-processing algorithm, non-negative matrix factorization, previously proposed for parsing object parts during object recognition. The possibility that unmixed left and right images can be regenerated at late stages within the visual system provides a mechanism for creating various binocular representations and interactions de novo in different cortical areas for different purposes, rather than inheriting then from early areas. This is a clear example how nonlinear algorithms can lead to highly non-intuitive behavior in neural information processing.

  6. Neuronal dynamics in the visual corticothalamic pathway revealed through binocular rivalry.

    Science.gov (United States)

    Varela, F J; Singer, W

    1987-01-01

    Single unit activity was recorded from principal cells in the A-laminae of the cat dorsal lateral geniculate nucleus (dLGN). A steady state pattern of afferent activation was induced by presenting a continuously drifting square wave grating of constant spatial frequency to the eye (the dominant eye) that provided the excitatory input to the recorded cell. Intermittently, a second grating stimulus was presented to the other, nondominant, eye. In most neurones nondominant eye stimulation led to inhibition of relay cell responses. The latency of this suppressive effect was unusually long (up to 1 s) and its intensity and duration depended critically on the similarity between the gratings that were presented to the two eyes. Typically suppression was strongest when the gratings differed in orientation, direction of movement and contrast and when the nondominant eye stimulus was moving rather than stationary. Ablation of visual cortex abolished these long latency and feature-dependent interferences. We conclude that the visual cortex and the corticothalamic projections are involved in the mediation of these interocular interactions. We interpret our results as support for the hypothesis that corticothalamic feedback modifies thalamic transmission as a function of the congruency between ongoing cortical activation patterns and afferent retinal signals. PMID:3582524

  7. Colour-grapheme synaesthesia affects binocular vision

    Directory of Open Access Journals (Sweden)

    Chris L.E. Paffen

    2011-11-01

    Full Text Available In colour-grapheme synaesthesia, non-coloured graphemes are perceived as being inherently coloured. In recent years, it has become evident that synaesthesia-inducing graphemes can affect visual processing in a manner comparable to real, physical colours. Here, we exploit the phenomenon of binocular rivalry in which incompatible images presented dichoptically compete for conscious expression. Importantly, the competition only arises if the two images are sufficiently different; if the difference between the images is small, the images will fuse into a single mixed percept. We show that achromatic graphemes that induce synaesthetic colour percepts evoke binocular rivalry, while without the synaesthetic percept, they do not. That is, compared to achromatically perceived graphemes, synaesthesia-inducing graphemes increase the predominance of binocular rivalry over binocular fusion. This finding shows that the synaesthetic colour experience can provide the conditions for evoking binocular rivalry, much like stimulus features that induce rivalry in normal vision.

  8. BINOCULAR RIVALRY AND NEURAL DYNAMICS*

    OpenAIRE

    Blake, Randolph; Lee, Sang-Hun; Heeger, David

    2008-01-01

    The Gestalt psychologists were fascinated with dynamics evident in visual perception, and they theorized that these dynamics were attributable to ever-changing electrical potentials within topographically organized brain fields. Dynamic field theory, as it was called, was subsequently discredited on grounds that the brain does not comprise a unitary electrical field but, instead, a richly interconnected network of discrete computing elements. Still, this modern conceptualization of brain func...

  9. Reduced Perceptual Exclusivity during Object and Grating Rivalry in Autism

    OpenAIRE

    Freyberg, J.; Robertson, C.E.; Baron-Cohen, S

    2015-01-01

    Background: The dynamics of binocular rivalry may be a behavioural footprint of excitatory and inhibitory neural transmission in visual cortex. Given the presence of atypical visual features in Autism Spectrum Conditions (ASC), and evidence in support of the idea of an imbalance in excitatory/inhibitory neural transmission in ASC, we hypothesized that binocular rivalry might prove a simple behavioural marker of such a transmission imbalance in the autistic brain. In support of this hypothesis...

  10. Attention modulation of stimulus rivalry under swapping paradigm

    OpenAIRE

    Doualot, Audrey; Simard, Mathieu; Saint-Amour, Dave

    2014-01-01

    Stimulus rivalry refers to the sustained periods of perceptual dominance that occur when different visual stimuli are swapped at a regular rate between eyes. This phenomenon is thought to involve mainly eye-independent mechanisms. Although several studies have reported that attention can increase image predominance in conventional binocular rivalry, it is unknown whether attention can specifically modulate stimulus rivalry. We addressed this question and manipulated the spatial characteristic...

  11. Onset rivalry: the initial dominance phase is independent of ongoing perceptual alternations

    OpenAIRE

    Jody eStanley; Jason eForte; Patrick eCavanagh; Olivia eCarter

    2011-01-01

    Binocular rivalry has been used to study a wide range of visual processes, from the integration of low-level features to the selection of signals that reach awareness. However, many of these studies do not distinguish between early and late phases of rivalry. There is clear evidence that the ‘onset’ stage of rivalry is characterized by stable, yet idiosyncratic biases that are independent of the subsequent alternations and perceptual biases experienced during sustained rivalry. Low-level stim...

  12. Nonlinear SSVEP responses are sensitive to the perceptual binding of visual hemifields during conventional ‘eye’ rivalry and interocular ‘percept’ rivalry

    OpenAIRE

    Sutoyo, David; Srinivasan, Ramesh

    2008-01-01

    We conducted behavioral and EEG experiments to identify physiological correlates of perceptual binding during two types of binocular rivalry: (1) conventional ‘eye’ rivalry where perception alternates between the two monocular images presented one to each eye and (2) interocular ‘percept’ rivalry, where perception alternates between percepts formed by grouping complementary hemifields one from each eye. We employed ‘frequency-tagging’ by flickering a grating in each hemifield of each eye at d...

  13. Quantum formalism to describe binocular rivalry

    OpenAIRE

    Manousakis, Efstratios

    2007-01-01

    On the basis of the general character and operation of the process of perception, a formalism is sought to mathematically describe the subjective or abstract/mental process of perception. It is shown that the formalism of orthodox quantum theory of measurement, where the observer plays a key role, is a broader mathematical foundation which can be adopted to describe the dynamics of the subjective experience. The mathematical formalism describes the psychophysical dynamics of the subjective or...

  14. Onset rivalry: the initial dominance phase is independent of ongoing perceptual alternations

    OpenAIRE

    Stanley, Jody; Forte, Jason D.; Cavanagh, Patrick; Carter, Olivia

    2011-01-01

    Binocular rivalry has been used to study a wide range of visual processes, from the integration of low-level features to the selection of signals that reach awareness. However, many of these studies do not distinguish between early and late phases of rivalry. There is clear evidence that the “onset” stage of rivalry is characterized by stable, yet idiosyncratic biases that are not evident in the average dominance of sustained rivalry viewing. Low-level stimulus features also have robust effec...

  15. Binocular astronomy

    CERN Document Server

    Tonkin, Stephen

    2014-01-01

    Binoculars have, for many, long been regarded as an “entry level” observational tool, and relatively few have used them as a serious observing instrument. This is changing! Many people appreciate the relative comfort of two-eyed observing, but those who use binoculars come to realize that they offer more than comfort. The view of the stars is more aesthetically pleasing and therefore binocular observers tend to observe more frequently and for longer periods. Binocular Astronomy, 2nd Edition, extends its coverage of small and medium binoculars to large and giant (i.e., up to 300mm aperture) binoculars and also binoviewers, which brings the work into the realm of serious observing instruments. Additionally, it goes far deeper into the varying optical characteristics of binoculars, giving newcomers and advanced astronomers the information needed to make informed choices on purchasing a pair. It also covers relevant aspects of the physiology of binocular (as in “both eyes”) observation. The first edition ...

  16. Analysis of the Difference between the Normal Vision and the Experiencing Cataract Vision on Binocular Color Fusion Limit

    Directory of Open Access Journals (Sweden)

    Shi Wang

    2015-10-01

    Full Text Available The optical instruments design for binocular vision has become an earnest demand towards the arrival of an ageing society. It is necessary to measure how color difference between left and right images by elderly people, which the color rivalry occurs. In this study, we measured the limit of binocular color fusion in the normal vision and the cataract experiencing vision which is aiming to simulate the elderly vision. The result shows that the color fusion limit curve in cataract experiencing vision are very similar with those in normal vision. Compared with the binocular color fusion limit in normal vision Δλdn, the binocular color fusion limit in cataract experiencing vision Δλdc is approximately 3~39nm increased on the central vision, 4~22nm on the retinal eccentricity of 3°, 5~23nm on the retinal eccentricity of 6°, and 5~24nm on the retinal eccentricity of 9°. The results also reveal that a similar limit is observed in the range of 520~560nm in both normal and cataract experiencing visions, which might give some potential evidences for designing 3D equipment. In addition, the minimum value of the binocular color fusion limit exists at 590nm either in the normal vision or the cataract experiencing vision during all retinal eccentricities

  17. Visual Rivalry Without Spatial Conflict

    OpenAIRE

    van Boxtel, Jeroen J. A.; Koch, Christof

    2012-01-01

    Visual rivalry has been extensively characterized in the literature. It is thought to require spatial conflict between overlapping visual presentations, even in studies that have found nonspatial (i.e. nonretinal) influences on rivalry. Unexpectedly, we identified visual rivalry in the complete absence of spatial conflict. Participants experienced visual rivalry when we placed a nonambiguous motion stimulus in a nonspatial (in our case, object-based) reference frame. Moreover, a stimulus that...

  18. A Sour Milk Rivalry

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A libel scandal involving Mengniu taints its image and deals a blow to China’s dairy industry Mengniu,with the 2008 milk contamination incident still fresh in people’s memories,has brought China’s dairy industry into the spotlight again-this time the attention focused on a bitter rivalry.

  19. Rivalry and innovation races

    OpenAIRE

    Kukuk, Martin; Stadler, Manfred

    2002-01-01

    Based on an extended game-theoretic innovation-race model, we derive some Schumpeterian hypotheses of the impact of technological rivalry, market power, technological opportunities and market size on the timing of product and process innovations. Using innovation data at the firm level in the German industrial sector, we estimate various versions of an econometric specification of the model with dichotomous innovation data by using a univariate binary probit model with qualitative regressor v...

  20. Canonical Cortical Circuit Model Explains Rivalry, Intermittent Rivalry, and Rivalry Memory

    OpenAIRE

    Shashaank Vattikuti; Phyllis Thangaraj; Hua W Xie; Gotts, Stephen J.; Alex Martin; Chow, Carson C.

    2016-01-01

    It has been shown that the same canonical cortical circuit model with mutual inhibition and a fatigue process can explain perceptual rivalry and other neurophysiological responses to a range of static stimuli. However, it has been proposed that this model cannot explain responses to dynamic inputs such as found in intermittent rivalry and rivalry memory, where maintenance of a percept when the stimulus is absent is required. This challenges the universality of the basic canonical cortical cir...

  1. Canonical Cortical Circuit Model Explains Rivalry, Intermittent Rivalry, and Rivalry Memory

    Science.gov (United States)

    Vattikuti, Shashaank; Xie, Hua W.; Gotts, Stephen J.; Martin, Alex; Chow, Carson C.

    2016-01-01

    It has been shown that the same canonical cortical circuit model with mutual inhibition and a fatigue process can explain perceptual rivalry and other neurophysiological responses to a range of static stimuli. However, it has been proposed that this model cannot explain responses to dynamic inputs such as found in intermittent rivalry and rivalry memory, where maintenance of a percept when the stimulus is absent is required. This challenges the universality of the basic canonical cortical circuit. Here, we show that by including an overlooked realistic small nonspecific background neural activity, the same basic model can reproduce intermittent rivalry and rivalry memory without compromising static rivalry and other cortical phenomena. The background activity induces a mutual-inhibition mechanism for short-term memory, which is robust to noise and where fine-tuning of recurrent excitation or inclusion of sub-threshold currents or synaptic facilitation is unnecessary. We prove existence conditions for the mechanism and show that it can explain experimental results from the quartet apparent motion illusion, which is a prototypical intermittent rivalry stimulus. PMID:27138214

  2. Canonical Cortical Circuit Model Explains Rivalry, Intermittent Rivalry, and Rivalry Memory.

    Directory of Open Access Journals (Sweden)

    Shashaank Vattikuti

    2016-05-01

    Full Text Available It has been shown that the same canonical cortical circuit model with mutual inhibition and a fatigue process can explain perceptual rivalry and other neurophysiological responses to a range of static stimuli. However, it has been proposed that this model cannot explain responses to dynamic inputs such as found in intermittent rivalry and rivalry memory, where maintenance of a percept when the stimulus is absent is required. This challenges the universality of the basic canonical cortical circuit. Here, we show that by including an overlooked realistic small nonspecific background neural activity, the same basic model can reproduce intermittent rivalry and rivalry memory without compromising static rivalry and other cortical phenomena. The background activity induces a mutual-inhibition mechanism for short-term memory, which is robust to noise and where fine-tuning of recurrent excitation or inclusion of sub-threshold currents or synaptic facilitation is unnecessary. We prove existence conditions for the mechanism and show that it can explain experimental results from the quartet apparent motion illusion, which is a prototypical intermittent rivalry stimulus.

  3. Canonical Cortical Circuit Model Explains Rivalry, Intermittent Rivalry, and Rivalry Memory.

    Science.gov (United States)

    Vattikuti, Shashaank; Thangaraj, Phyllis; Xie, Hua W; Gotts, Stephen J; Martin, Alex; Chow, Carson C

    2016-05-01

    It has been shown that the same canonical cortical circuit model with mutual inhibition and a fatigue process can explain perceptual rivalry and other neurophysiological responses to a range of static stimuli. However, it has been proposed that this model cannot explain responses to dynamic inputs such as found in intermittent rivalry and rivalry memory, where maintenance of a percept when the stimulus is absent is required. This challenges the universality of the basic canonical cortical circuit. Here, we show that by including an overlooked realistic small nonspecific background neural activity, the same basic model can reproduce intermittent rivalry and rivalry memory without compromising static rivalry and other cortical phenomena. The background activity induces a mutual-inhibition mechanism for short-term memory, which is robust to noise and where fine-tuning of recurrent excitation or inclusion of sub-threshold currents or synaptic facilitation is unnecessary. We prove existence conditions for the mechanism and show that it can explain experimental results from the quartet apparent motion illusion, which is a prototypical intermittent rivalry stimulus. PMID:27138214

  4. What is binocular disparity?

    OpenAIRE

    Lappin, Joseph S.

    2014-01-01

    What are the geometric primitives of binocular disparity? The Venetian blind effect and other converging lines of evidence indicate that stereoscopic depth perception derives from disparities of higher-order structure in images of surfaces. Image structure entails spatial variations of intensity, texture, and motion, jointly structured by observed surfaces. The spatial structure of binocular disparity corresponds to the spatial structure of surfaces. Independent spatial coordinates are not ne...

  5. What is Binocular Disparity?

    OpenAIRE

    Lappin, Joseph S.

    2014-01-01

    What are the geometric primitives of binocular disparity? The Venetian blind effect and other converging lines of evidence indicate that stereo-scopic depth perception derives from disparities of higher-order structure in images of surfaces. Image structure entails spatial variations of in-tensity, texture, and motion, jointly structured by observed surfaces. The spatial structure of bin-ocular disparity corresponds to the spatial struc-ture of surfaces. Independent spatial coordinates are no...

  6. Binocular advantages in reading.

    Science.gov (United States)

    Jainta, Stephanie; Blythe, Hazel I; Liversedge, Simon P

    2014-03-01

    Reading, an essential skill for successful function in today's society, is a complex psychological process involving vision, memory, and language comprehension. Variability in fixation durations during reading reflects the ease of text comprehension, and increased word frequency results in reduced fixation times. Critically, readers not only process the fixated foveal word but also preprocess the parafoveal word to its right, thereby facilitating subsequent foveal processing. Typically, text is presented binocularly, and the oculomotor control system precisely coordinates the two frontally positioned eyes online. Binocular, compared to monocular, visual processing typically leads to superior performance, termed the "binocular advantage"; few studies have investigated the binocular advantage in reading. We used saccade-contingent display change methodology to demonstrate the benefit of binocular relative to monocular text presentation for both parafoveal and foveal lexical processing during reading. Our results demonstrate that denial of a unified visual signal derived from binocular inputs provides a cost to the efficiency of reading, particularly in relation to high-frequency words. Our findings fit neatly with current computational models of eye movement control during reading, wherein successful word identification is a primary determinant of saccade initiation. PMID:24530062

  7. What is Binocular Disparity?

    Directory of Open Access Journals (Sweden)

    Joseph S Lappin

    2014-08-01

    Full Text Available What are the geometric primitives of binocular disparity? The Venetian blind effect and other converging lines of evidence indicate that stereo-scopic depth perception derives from disparities of higher-order structure in images of surfaces. Image structure entails spatial variations of in-tensity, texture, and motion, jointly structured by observed surfaces. The spatial structure of bin-ocular disparity corresponds to the spatial struc-ture of surfaces. Independent spatial coordinates are not necessary for stereoscopic vision. Stere-opsis is highly sensitive to structural disparities associated with local surface shape. Disparate positions on retinal anatomy are neither neces-sary nor sufficient for stereopsis.

  8. What is binocular disparity?

    Science.gov (United States)

    Lappin, Joseph S

    2014-01-01

    What are the geometric primitives of binocular disparity? The Venetian blind effect and other converging lines of evidence indicate that stereoscopic depth perception derives from disparities of higher-order structure in images of surfaces. Image structure entails spatial variations of intensity, texture, and motion, jointly structured by observed surfaces. The spatial structure of binocular disparity corresponds to the spatial structure of surfaces. Independent spatial coordinates are not necessary for stereoscopic vision. Stereopsis is highly sensitive to structural disparities associated with local surface shape. Disparate positions on retinal anatomy are neither necessary nor sufficient for stereopsis. PMID:25161634

  9. Sibling Rivalry: A Parent Education Perspective.

    Science.gov (United States)

    Calladine, Carole E.

    1983-01-01

    Identifies three styles of sibling rivalry and three parent leadership styles, discussing parental mediation of sibling disputes through contracting and providing examples of group discipline techniques that facilitate development of less negative forms of rivalry and that support positive sibling bonding. (RH)

  10. Octonions and Binocular Mobilevision

    OpenAIRE

    Juriev, Denis

    1994-01-01

    This paper is devoted to an interaction of 2 objects: the 1st of them is octonions, the classical structure of pure mathematics, the 2nd one is Mobilevision, the recently developped technique of computer graphics. Namely, it is shown that the binocular Mobilevision maybe elaborated by use of the octonionic colour space - the 7-dimensional extension of the classical one, which includes a strange overcolour besides two triples of ordinary ones (blue,green, red for left and right eyes). Contents...

  11. Binocular eye movements in health and disease

    Science.gov (United States)

    Tyler, Christopher W.

    2013-03-01

    Binocular eye movements form a finely-tuned system that requires accurate coordination of the oculomotor dynamics and supports the vergence movements for tracking the fine binocular disparities required for 3D vision, and are particularly susceptible to disruption by brain injury and other neural dysfunctions. Saccadic dynamics for a population of 84 diverse participants show tight coefficients of variation of 2-10% of the mean value of each parameter. Significantly slower dynamics were seen for vertical upward saccades. Binocular coordination of saccades was accurate to within 1-4%, implying the operation of brainstem coordination mechanisms rather than independent cortical control of the two eyes. A new principle of oculomotor control - reciprocal binocular inhibition - is introduced to complement Sherrington's and Hering's Laws. This new law accounts for the fact that symmetrical vergence responses are about five times slower than saccades of the same amplitude, although a comprehensive analysis of asymmetrical vergence responses revealed unexpected variety in vergence dynamics. This analysis of the variety of human vergence responses thus contributes substantially to the understanding of the oculomotor control mechanisms underlying the generation of vergence movements and of the deficits in the oculomotor control resulting from mild traumatic brain injury.

  12. MONOCULAR AND BINOCULAR VISION IN THE PERFORMANCE OF A COMPLEX SKILL

    Directory of Open Access Journals (Sweden)

    Thomas Heinen

    2011-09-01

    Full Text Available The goal of this study was to investigate the role of binocular and monocular vision in 16 gymnasts as they perform a handspring on vault. In particular we reasoned, if binocular visual information is eliminated while experts and apprentices perform a handspring on vault, and their performance level changes or is maintained, then such information must or must not be necessary for their best performance. If the elimination of binocular vision leads to differences in gaze behavior in either experts or apprentices, this would answer the question of an adaptive gaze behavior, and thus if this is a function of expertise level or not. Gaze behavior was measured using a portable and wireless eye-tracking system in combination with a movement-analysis system. Results revealed that gaze behavior differed between experts and apprentices in the binocular and monocular conditions. In particular, apprentices showed less fixations of longer duration in the monocular condition as compared to experts and the binocular condition. Apprentices showed longer blink duration than experts in both, the monocular and binocular conditions. Eliminating binocular vision led to a shorter repulsion phase and a longer second flight phase in apprentices. Experts exhibited no differences in phase durations between binocular and monocular conditions. Findings suggest, that experts may not rely on binocular vision when performing handsprings, and movement performance maybe influenced in apprentices when eliminating binocular vision. We conclude that knowledge about gaze-movement relationships may be beneficial for coaches when teaching the handspring on vault in gymnastics

  13. Glossiness representation using binocular color difference.

    Science.gov (United States)

    Jung, Woo-Soon; Moon, Young-Gyu; Park, Jae-Hyun; Song, Jang-Kun

    2013-07-15

    We demonstrate that a binocular color difference can be used to express the surface glossiness of an object on 3D display devices without being accompanied by a specular reflection pattern. A simple image with a binocular color difference provides a similar surface appearance impression to a real object that has the same binocular color difference. It is found that human binocular perception is likely to interpret binocular color difference as spectral reflectance rather than as transparency. Binocular glossiness is caused not only by a binocular lightness difference but also by a chromatic or hue difference. PMID:23939119

  14. Perceptual "blankout" of monocular homogeneous fields (Ganzfelder) is prevented with binocular viewing.

    Science.gov (United States)

    Bolanowski, S J; Doty, R W

    1987-01-01

    The loss of visual perception or "blankout" which occurs when a homogeneous field (Ganzfeld) is presented monocularly is prevented when the same field is viewed binocularly. Thus, blankout cannot be retinal; and contours or transients in time and space are unnecessary for the continuous maintenance of visual perception. Experiments are reported in which blankout ensues only if the two eyes receive luminance disparities ca 0.75 log I. Furthermore, blankout is only marginally affected by stimulus intensity, nor is it dependent on stimulus hue. However, equally luminant but disparate hues presented to the two eyes produce perceptions reminiscent of blankout, with the darkness of blankout replaced with that of color. It is hypothesized that the underlying mechanisms have a commonality in the phenomena of blankout and binocular rivalry but several noncongruent features require explanation. PMID:3660657

  15. Binocular indirect argon laser photocoagulator.

    OpenAIRE

    Mizuno, K

    1981-01-01

    The binocular indirect argon laser photocoagulator was newly designed to enable visualisation of the entire fundus during panretinal laser photocoagulation and to treat retinal tears immediately after buckling procedures of the sclera. The lamp housing of the binocular ophthalmoscope was remodelled and adjusted so that the laser beam and illuminating light are coaxial after leaving the ophthalmoscope. The blocking filter was permanently fixed in the eye-pieces to lighten the weight of the oph...

  16. Generic Rivalry Strategies in Business Networks: Towards a Conceptualization

    DEFF Research Database (Denmark)

    Andersen, Poul Houman

    2008-01-01

    This paper discusses rivalry as a process of occupying incompatible positions within business networks. Rivalry is linked to different forms of strategizing as they unfold in stable and dynamic business contexts and a framework of four different types of rivalry is suggested. Furthermore, proposi...

  17. Binocular Combination of Second-Order Stimuli

    OpenAIRE

    Zhou, Jiawei; Liu, Rong; Zhou, Yifeng; Hess, Robert F.

    2014-01-01

    Phase information is a fundamental aspect of visual stimuli. However, the nature of the binocular combination of stimuli defined by modulations in contrast, so-called second-order stimuli, is presently not clear. To address this issue, we measured binocular combination for first- (luminance modulated) and second-order (contrast modulated) stimuli using a binocular phase combination paradigm in seven normal adults. We found that the binocular perceived phase of second-order gratings depends on...

  18. Optimization Design for Digital Binoculars

    Institute of Scientific and Technical Information of China (English)

    CEN Jun-bo; CHEN Wei-min; LI Hui; HUANG Shang-lian

    2005-01-01

    In order to develop competitive and high performance/cost ratio of digital binoculars, design scheme should be optimized in term of technical capacity, economic benefit, product performance, risk management, etc. The common optimization method is limited in qualitative analysis, and the parameter optimization method is limited in obtaining optimal parameter only from technical side. Each method has its limitation. Based on the analysis of digital binoculars parameters, optional design schemes are laid down.Analytic hierarchy process combined the qualitative analysis with the quantitative analysis together. The design schemes are optimized, and result is worked out.

  19. Early Visual Responses Predict Conscious Face Perception within and between Subjects during Binocular Rivalry

    DEFF Research Database (Denmark)

    Sandberg, Kristian; Bahrami, Bahador; Kanai, Ryota;

    2013-01-01

    Previous studies indicate that conscious face perception may be related to neural activity in a large time window around 170–800 msec after stimulus presentation, yet in the majority of these studies changes in conscious experience are confounded with changes in physical stimulation. Using...... predict perception better than chance. In addition, source space analyses showed that sources in the early and late visual system predicted conscious perception more accurately than frontal and parietal sites, although conscious perception could also be decoded there. Finally, the patterns of neural...

  20. Reinforcement of perceptual inference: reward and punishment alter conscious visual perception during binocular rivalry

    OpenAIRE

    Wilbertz, Gregor; van Slooten, Joanne; Sterzer, Philipp

    2014-01-01

    Perception is an inferential process, which becomes immediately evident when sensory information is conflicting or ambiguous and thus allows for more than one perceptual interpretation. Thinking the idea of perception as inference through to the end results in a blurring of boundaries between perception and action selection, as perceptual inference implies the construction of a percept as an active process. Here we therefore wondered whether perception shares a key characteristic of action se...

  1. On the visual system's architecture underlying binocular rivalry and motion perception

    NARCIS (Netherlands)

    Boxtel, J.J.A. van

    2008-01-01

    Our everyday visual perception is supported by a complicated set of interactions between different brain areas. These areas often have a specific function. A lot of communication takes place between, and also within, these areas. The total set of interactions between and within the different brain a

  2. Sibling Rivalry in Educational Attainment: The German Case

    OpenAIRE

    Bauer, Thomas K.; Ira N. Gang

    2000-01-01

    Recent studies exploring sibling rivalry in the allocation of household resources in the U.S. produce conflicting results. We contribute to this discussion by addressing the role of sibling rivalry in educational attainment in Germany. Using the German Socioeconomic Panel (GSOEP) we are able to distinguish how the effects of sibling rivalry vary by cultural affiliation, i.e., among families of West German, East German and foreign origin. We also point out and correct for a reference group pro...

  3. Life history consequences of mammal sibling rivalry

    OpenAIRE

    Stockley, P; Parker, G.A.

    2002-01-01

    Mammal life history traits relating to growth and reproduction are extremely diverse. Sibling rivalry may contribute to selection pressures influencing this diversity, because individuals that are relatively large at birth typically have an advantage in competition for milk. However, selection for increased growth rate is likely to be constrained by kin selection and physiological costs. Here, we present and test a model examining the ESS (evolutionarily stable strategy) balance between these...

  4. A monocular contribution to stimulus rivalry

    OpenAIRE

    Brascamp, Jan; Sohn, Hansem; Lee, Sang-Hun; Blake, Randolph

    2013-01-01

    When corresponding areas of the two eyes view dissimilar images, stable perception gives way to visual competition wherein perceptual awareness alternates between those images. Moreover, a given image can remain visually dominant for several seconds at a time even when the competing images are swapped between the eyes multiple times each second. This perceptual stability across eye swaps has led to the widespread belief that this unique form of visual competition, dubbed stimulus rivalry, is ...

  5. Life history consequences of mammal sibling rivalry.

    Science.gov (United States)

    Stockley, P; Parker, G A

    2002-10-01

    Mammal life history traits relating to growth and reproduction are extremely diverse. Sibling rivalry may contribute to selection pressures influencing this diversity, because individuals that are relatively large at birth typically have an advantage in competition for milk. However, selection for increased growth rate is likely to be constrained by kin selection and physiological costs. Here, we present and test a model examining the ESS (evolutionarily stable strategy) balance between these constraints and advantages associated with increased prenatal growth in mammal sibling rivalry. Predictions of the model are supported by results of comparative analyses for the Carnivora and Insectivora, which demonstrate an increase in prenatal growth rate with increasing intensity of postnatal scramble competition, and a decrease in postnatal growth rate relative to size at birth. Because increased prenatal growth rates are predicted to select for reduced gestation length under certain conditions, our study also indicates that sibling rivalry may contribute to selection pressures influencing variation in altriciality and precociality among mammals. PMID:12237403

  6. Correcting intermittent central suppression improves binocular marksmanship.

    Science.gov (United States)

    Hussey, Eric S

    2007-04-01

    Intermittent central suppression (ICS) is a defect in normal binocular (two-eyed) vision that causes confusion in visual detail. ICS is a repetitive intermittent loss of visual sensation in the central area of vision. As the central vision of either eye "turns on and off", aiming errors in sight can occur that must be corrected when both eyes are seeing again. Any aiming errors in sight might be expected to interfere with marksmanship during two-eyed seeing. We compared monocular (one-eyed, patched) and binocular (two-eyed) marksmanship with pistol shooting with an Army ROTC cadet before and after successful therapy for diagnosed ICS. Pretreatment, monocular marksmanship was significantly better than binocular marksmanship, suggesting defective binocularity reduced accuracy. After treatment for ICS, binocular and monocular marksmanship were essentially the same. Results confirmed predictions that with increased visual stability from correcting the suppression, binocular and monocular marksmanship accuracies should merge. PMID:17484315

  7. On rivalry and goal pursuit: Shared competitive history, legacy concerns, and strategy selection.

    Science.gov (United States)

    Converse, Benjamin A; Reinhard, David A

    2016-02-01

    Seven studies converge to show that prompting people to think about a rival versus a nonrival competitor causes them to view current competitions as more connected to past ones, to be more concerned with long-term legacy, and to pursue personal goals in a more eager, less cautious manner. These results are consistent with a social-cognitive view of rivalry that defines it as a competitive relational schema. A preliminary analysis revealed that people were more likely to appeal to past competitions to explain the importance of current rivalry than nonrivalry contests. Experiment 1 showed that people view rivalry versus nonrivalry competitions as more embedded in an ongoing competitive narrative and that this perception increases legacy concerns. The next 2 experiments used a causal chain approach to examine the possibility of legacy concerns acting as a mediator between rivalry and eagerness. Experiment 2a demonstrated that longer (vs. shorter) competitive histories are associated with increased legacy concerns. Experiment 2b manipulated legacy concerns and found that this shifted regulatory focus toward eagerness. Finally, 3 experiments tested the direct effect of thinking about a rival on eager strategy selection: Thinking about rivals (vs. nonrivals) led people to be more interested in offensive than defensive strategies (Experiment 3), to initiate rather than delay their goal pursuit (Experiment 4), and to rely on spontaneous rather than deliberative reasoning (Experiment 5). We suggest that rivalries affect how people view their goals and the strategies they use for pursuing them, and that these effects are at least partially attributable to the shared history between individuals and their rivals. PMID:26479360

  8. Competitive and rivalry behaviors in international business exchanges

    DEFF Research Database (Denmark)

    Medlin, C. J.; Ellegaard, Chris

    primarily towards the customers or towards other firms. We explore the theoretical distinctions between non-competitive, competitive, and rivalry firm behavior through an analysis of wine exporters and importers of fine wine to Denmark from Southern Australia. We find examples of competitive and rivalry...

  9. India China Rivalry and Competition in Southeast Asia

    DEFF Research Database (Denmark)

    Schmidt, Johannes Dragsbæk

    2011-01-01

    . This struggle comes in different forms, sectors and countries and is in many cases intertwined geo-political and geo-economic rivalry. It is not always possible to distinguish between traditional security related rivalry or mere state based or private sector based competition. As this paper argues the...... rivalry which is unfolding in the Southeast Asian region is being played out in light of the wider global arena where also the interest and capabilities of the United States must be taken into consideration. The rivalry is manifold therefore the analysis must be based on an approach which seeks to explain...... historical and strategic relationship between India and China has been briefly outlined. Second section recaps the theoretical considerations while part three focuses on China and India’s encroachment into Southeast Asia. Part four gives examples of competition and rivalry in energy and related resources...

  10. The Sibling Relationship: Friendship or Rivalry?

    OpenAIRE

    Wallace, Edel

    2012-01-01

    The aim of this study is to examine the sibling relationship from the perspective of both siblings in order to add to the understanding of potentially one of the most important relationship of an individual’s life. In particular, questions were asked about how the relationship is affected in terms of warmth, conflict and rivalry by a number of variables; gender, level of contact and number of siblings in the family. This study also sought to determine if there is a gender divide in the type o...

  11. Binocular combination of second-order stimuli.

    Science.gov (United States)

    Zhou, Jiawei; Liu, Rong; Zhou, Yifeng; Hess, Robert F

    2014-01-01

    Phase information is a fundamental aspect of visual stimuli. However, the nature of the binocular combination of stimuli defined by modulations in contrast, so-called second-order stimuli, is presently not clear. To address this issue, we measured binocular combination for first- (luminance modulated) and second-order (contrast modulated) stimuli using a binocular phase combination paradigm in seven normal adults. We found that the binocular perceived phase of second-order gratings depends on the interocular signal ratio as has been previously shown for their first order counterparts; the interocular signal ratios when the two eyes were balanced was close to 1 in both first- and second-order phase combinations. However, second-order combination is more linear than previously found for first-order combination. Furthermore, binocular combination of second-order stimuli was similar regardless of whether the carriers in the two eyes were correlated, anti-correlated, or uncorrelated. This suggests that, in normal adults, the binocular phase combination of second-order stimuli occurs after the monocular extracting of the second-order modulations. The sensory balance associated with this second-order combination can be obtained from binocular phase combination measurements. PMID:24404180

  12. Binocular combination of second-order stimuli.

    Directory of Open Access Journals (Sweden)

    Jiawei Zhou

    Full Text Available Phase information is a fundamental aspect of visual stimuli. However, the nature of the binocular combination of stimuli defined by modulations in contrast, so-called second-order stimuli, is presently not clear. To address this issue, we measured binocular combination for first- (luminance modulated and second-order (contrast modulated stimuli using a binocular phase combination paradigm in seven normal adults. We found that the binocular perceived phase of second-order gratings depends on the interocular signal ratio as has been previously shown for their first order counterparts; the interocular signal ratios when the two eyes were balanced was close to 1 in both first- and second-order phase combinations. However, second-order combination is more linear than previously found for first-order combination. Furthermore, binocular combination of second-order stimuli was similar regardless of whether the carriers in the two eyes were correlated, anti-correlated, or uncorrelated. This suggests that, in normal adults, the binocular phase combination of second-order stimuli occurs after the monocular extracting of the second-order modulations. The sensory balance associated with this second-order combination can be obtained from binocular phase combination measurements.

  13. Simulating binocular vision for no-reference 3D visual quality measurement.

    Science.gov (United States)

    Zhou, Wu-Jie; Yu, Lu; Wu, Ming-Wei

    2015-09-01

    Perceptual quality measurement of three-dimensional (3D) visual signals has become a fundamental challenge in 3D imaging fields. This paper proposes a novel no-reference (NR) 3D visual quality measurement (VQM) metric that uses simulations of the primary visual cortex (V1) of binocular vision. As the major technical contribution of this study, perceptual properties of simple and complex cells are considered for NR 3D-VQM. More specifically, the metric simulates the receptive fields of simple cells (one class of V1 neurons) using Gaussian derivative functions, and the receptive fields of complex cells (the other class of V1 neurons) using disparity energy responses and binocular rivalry responses. Subsequently, various quality-aware features are extracted from the primary visual cortex; these will change in the presence of distortions. Finally, those features are mapped to the subjective quality score of the distorted 3D visual signal by using support vector regression (SVR). Experiments on two publicly available 3D databases confirm the effectiveness of our proposed metric, compared to the relevant full-reference (FR) and NR metrics. PMID:26368467

  14. Enhancement of bistable perception associated with visual stimulus rivalry

    OpenAIRE

    Kang, Min-Suk; Blake, Randolph

    2008-01-01

    Rapid, repetitive exchange of dissimilar, rival stimuli between the two eyes can produce slow alternations in perceptual dominance. This phenomenon, called stimulus rivalry, is potentially important for studying resolution of visual conflict associated with neural processing beyond the level of interocular competition. As previously implemented, however, stimulus rivalry can be difficult for some observers to experience, and it tends to occur within a relatively narrow range of contrasts and ...

  15. Evaluating relative accommodations in general binocular dysfunctions

    OpenAIRE

    García Muñoz, Ángel; Cacho Martínez, Pilar; Lara Lacarcel, Francisco

    2001-01-01

    Purpose. To examine the relationship between relative accommodation and general binocular disorders and to establish their importance in the diagnosis of these anomalies. Methods. We analyzed data of negative relative accommodation (NRA) and positive relative accommodation (PRA) in 69 patients with nonstrabismic binocular anomalies. Results. Statistical analysis showed that low values of NRA and PRA were not associated with any particular disorder. High values of PRA (>3.50 D) were related to...

  16. 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 (<4%), consistent with previous studies, and at high contrasts (≥34%), which has not been previously reported. However, control experiments showed no binocular advantage at high contrasts in the presence of a fixation point or for observers without accommodation. We evaluated two putative contrast-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

  17. Binocular form deprivation influences the visual cortex

    Institute of Scientific and Technical Information of China (English)

    Mingming Liu; Chuanhuang Weng; Hanping Xie; Wei Qin

    2012-01-01

    1a-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are considered to play a crucial role in synaptic plasticity in the developing visual cortex. In this study, we established a rat model of binocular form deprivation by suturing the rat binocular eyelids before eye-opening at postnatal day 14. During development, the decay time of excitatory postsynaptic currents mediated by 1a-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid receptors of normal rats became longer after eyeopening; however, the decay time did not change significantly in binocular form deprivation rats. The peak value in the normal group became gradually larger with age, but there was no significant change in the binocular form deprivation group. These findings indicate that binocular form deprivation influences the properties of excitatory postsynaptic currents mediated by β-amino-3- hydroxy-5-methyl-4-isoxazolepropionic acid receptors in the rat visual cortex around the end of the critical period, indicating that form stimulation is associated with the experience-dependent modification of neuronal synapses in the visual cortex.

  18. Book review: The great rivalry: Gladstone and Disraeli: a dual biography

    OpenAIRE

    Berry, Richard

    2013-01-01

    "The Great Rivalry: Gladstone and Disraeli: A Dual Biography." Dick Leonard. IB Tauris. June 2013. --- Benjamin Disraeli and William Ewart Gladstone are without doubt the two most iconic figures of Victorian politics, whose distinctly different personalities and policies led to 28 years of bitter political rivalry. In The Great Rivalry, Dick Leonard aims to provide the full story of their rivalry and its origins, comparing the upbringing, education and personalities of the two leaders, as wel...

  19. Domestic Rivalry and Export Performance: Theory and Evidence from International Airline Markets

    OpenAIRE

    Joseph A. Clougherty; Zang, Anming

    2008-01-01

    "The much-studied relationship between domestic rivalry and export performance consists of those supporting a national-champion rationale, and those supporting a rivalry rationale. While the empirical literature generally supports the positive effects of domestic rivalry, the national-champion rationale actually rests on firmer theoretical ground. We address this inconsistency by providing a theoretical framework that illustrates three paths via which domestic rivalry translates into enhanced...

  20. Competitive rivalry, social disposition, and subjective well-being: an experiment

    NARCIS (Netherlands)

    J. Brandts; A. Riedl; F. van Winden

    2009-01-01

    This paper experimentally studies the effects of competitive rivalry in a social dilemma where people's actions cannot be contractually fixed. We find that, in comparison with no rivalry, the presence of rivalry does neither increase efficiency nor does it yield any gains in earnings for the short s

  1. Binocular summation of contrast remains intact in strabismic amblyopia

    OpenAIRE

    Baker, Daniel H.; Meese, Tim S.; Mansouri, Behzad; Hess, Robert F.

    2007-01-01

    PURPOSE. Strabismic amblyopia is typically associated with several visual deficits, including loss of contrast sensitivity in the amblyopic eye and abnormal binocular vision. Binocular summation ratios (BSRs) are usually assessed by comparing contrast sensitivity for binocular stimuli (sensBIN) with that measured in the good eye alone (sensGOOD), giving BSR = sensBIN/sensGOOD. This calculation provides an operational index of clinical binocular function, but does not assess whether neuronal m...

  2. Onset rivalry: factors that succeed and fail to bias selection.

    Science.gov (United States)

    Attarha, Mouna; Moore, Cathleen M

    2015-02-01

    This project examined whether previous visual history can bias perceptual dominance during onset rivalry. A predictive sequence of non-rivalrous stimuli preceded dichoptically presented rivalrous displays. One of the dichoptic images was the implied next step of the preceding sequence while the other was not. Observers reported their initial dominant percept. Across five experiments, we found that motion sequences biased perceptual selection such that a rivalrous stimulus that continued a motion sequence tended to dominate one that did not. However, signals generated by complex pattern of motion information or verbal-semantic information had no influence on selection. These results are consistent with the view that onset rivalry is an early phase of rivalry that is likely insensitive to modulation by factors originating beyond the visual system. PMID:25384763

  3. ASEAN and Strategic Rivalry among the Great Powers in Asia

    Directory of Open Access Journals (Sweden)

    Fenna Egberink

    2010-01-01

    Full Text Available This paper looks at ASEAN’s role in the context of the three main bilateral relations among the great powers in Asia: China-US, China-Japan, and China-India. The authors argue that although ASEAN’s influence is limited in terms of geographical reach and its impact on actual security issues, Southeast Asia is potentially an important object of great power rivalry and thus the sub-region is highly relevant to Asian geopolitics. The key question with regard to geopolitical stability is how ASEAN will deal with increased great power rivalries in its own sub-region.

  4. Night myopia is reduced in binocular vision.

    Science.gov (United States)

    Chirre, Emmanuel; Prieto, Pedro M; Schwarz, Christina; Artal, Pablo

    2016-06-01

    Night myopia, which is a shift in refraction with light level, has been widely studied but still lacks a complete understanding. We used a new infrared open-view binocular Hartmann-Shack wave front sensor to quantify night myopia under monocular and natural binocular viewing conditions. Both eyes' accommodative response, aberrations, pupil diameter, and convergence were simultaneously measured at light levels ranging from photopic to scotopic conditions to total darkness. For monocular vision, reducing the stimulus luminance resulted in a progression of the accommodative state that tends toward the subject's dark focus or tonic accommodation and a change in convergence following the induced accommodative error. Most subjects presented a myopic shift of accommodation that was mitigated in binocular vision. The impact of spherical aberration on the focus shift was relatively small. Our results in monocular conditions support the hypothesis that night myopia has an accommodative origin as the eye progressively changes its accommodation state with decreasing luminance toward its resting state in total darkness. On the other hand, binocularity restrains night myopia, possibly by using fusional convergence as an additional accommodative cue, thus reducing the potential impact of night myopia on vision at low light levels. PMID:27333457

  5. Brotherhood/Sisterhood Begin at Home: Notes on Sibling Rivalry.

    Science.gov (United States)

    Katz, Lilian G.

    Parents who are frequently frustrated and troubled by rivalry among their children may find the following suggestions helpful. If fighting between siblings is bothersome, stop it. Don't lecture, moralize or nag. Once the unpleasant behavior is stopped, look for possible causes and ways of dealing with it. Children's versions of disputes and other…

  6. Remote landslide mapping using a laser rangefinder binocular and GPS

    Directory of Open Access Journals (Sweden)

    M. Santangelo

    2010-12-01

    Full Text Available We tested a high-quality laser rangefinder binocular coupled with a GPS receiver connected to a Tablet PC running dedicated software to help recognize and map in the field recent rainfall-induced landslides. The system was tested in the period between March and April 2010, in the Monte Castello di Vibio area, Umbria, Central Italy. To test the equipment, we measured thirteen slope failures that were mapped previously during a visual reconnaissance field campaign conducted in February and March 2010. For reference, four slope failures were also mapped by walking the GPS receiver along the landslide perimeter. Comparison of the different mappings revealed that the geographical information obtained remotely for each landslide by the rangefinder binocular and GPS was comparable to the information obtained by walking the GPS around the landslide perimeter, and was superior to the information obtained through the visual reconnaissance mapping. Although our tests were not exhaustive, we maintain that the system is effective to map recent rainfall induced landslides in the field, and we foresee the possibility of using the same (or similar system to map landslides, and other geomorphological features, in other areas.

  7. Motion Parallax is Asymptotic to Binocular Disparity

    CERN Document Server

    Stroyan, Keith

    2010-01-01

    Researchers especially beginning with (Rogers & Graham, 1982) have noticed important psychophysical and experimental similarities between the neurologically different motion parallax and stereopsis cues. Their quantitative analysis relied primarily on the "disparity equivalence" approximation. In this article we show that retinal motion from lateral translation satisfies a strong ("asymptotic") approximation to binocular disparity. This precise mathematical similarity is also practical in the sense that it applies at normal viewing distances. The approximation is an extension to peripheral vision of (Cormac & Fox's 1985) well-known non-trig central vision approximation for binocular disparity. We hope our simple algebraic formula will be useful in analyzing experiments outside central vision where less precise approximations have led to a number of quantitative errors in the vision literature.

  8. Trinocular Calibration Method Based on Binocular Calibration

    OpenAIRE

    CAO Dan-Dan; Luo, Chun; GAO Shu-Yuan; Wang, Yun; Li, Wen-Bin; XU Zhen-Ying

    2012-01-01

    In order to solve the self-occlusion problem in plane-based multi-camera calibration system and expand the measurement range, a tri-camera vision system based on binocular calibration is proposed. The three cameras are grouped into two pairs, while the public camera is taken as the reference to build the global coordinate. By calibration of the measured absolute distance and the true absolute distance, global calibration is realized. The MRE (mean relative error) of the global calibration of ...

  9. Target Image Matching Algorithm Based on Binocular CCD Ranging

    Directory of Open Access Journals (Sweden)

    Dongming Li

    2014-01-01

    Full Text Available This paper proposed target image in a subpixel level matching algorithm for binocular CCD ranging, which is based on the principle of binocular CCD ranging. In the paper, firstly, we introduced the ranging principle of the binocular ranging system and deduced a binocular parallax formula. Secondly, we deduced the algorithm which was named improved cross-correlation matching algorithm and cubic surface fitting algorithm for target images matched, and it could achieve a subpixel level matching for binocular CCD ranging images. Lastly, through experiment we have analyzed and verified the actual CCD ranging images, then analyzed the errors of the experimental results and corrected the formula of calculating system errors. Experimental results showed that the actual measurement accuracy of a target within 3 km was higher than 0.52%, which meet the accuracy requirements of the high precision binocular ranging.

  10. Attentional switching in humans and flies: rivalry in large and miniature brains

    Directory of Open Access Journals (Sweden)

    Steven Mark Miller

    2012-01-01

    Full Text Available Human perception, and consequently behaviour, is driven by attention dynamics. In the special case of rivalry, where attention alternates between competing percepts, such dynamics can be measured and their determinants investigated. A recent study in the fruit fly, Drosophila melanogaster, now shows that the origins of attentional rivalry may be quite ancient. Furthermore, individual variation exists in the rate of attentional rivalry in both humans and flies, and in humans this is under substantial genetic influence. In the pathophysiological realm, slowing of rivalry rate is associated with the heritable psychiatric condition, bipolar disorder. Fly rivalry may therefore prove a powerful model to examine genetic and molecular influences on rivalry rate, and may even shed light on human cognitive and behavioural dysfunction.

  11. General binocular disorders: prevalence in a clinic population

    OpenAIRE

    Lara Lacarcel, Francisco; Cacho Martínez, Pilar; García Muñoz, Ángel; Megías, Ramón

    1999-01-01

    The purpose of this paper was to study the prevalence of nonstrabismic accommodative and binocular dysfunctions in a clinical population. We examined 265 symptomatic patients who were chosen from an optometric clinic. We performed several tests to diagnose any form of refractive, accommodative or binocular dysfunction. Of the 265 subjects examined, 59 patients (22.3%) had some form of accommodative or binocular dysfunction and required not just the correction of the refractive error but a spe...

  12. Randot stereoacuity at various binocular combinations of snellen acuity

    Directory of Open Access Journals (Sweden)

    Menon Vimala

    1997-01-01

    Full Text Available Binocular combinations of Snellen acuity were varied from 6/60 to 6/6 in standard steps in twenty normal adults and Randot stereoacuity was measured at each level. Using the 560 unique stereoacuity scores thus obtained, a nomogram was constructed which provides expected stereoacuity scores at all unique binocular combinations of Snellen acuity. It was seen that there is a linear correlation between binocular isoacuity (at level 6/36 or better and Randot stereoacuity.

  13. Binocular Vision Problems in Refractive Surgery Patients: Vision Therapy Case Reports

    Directory of Open Access Journals (Sweden)

    Gina Day, OD

    2015-02-01

    Full Text Available Background: Some post-LASIK patients complain of blurry distance vision months after refractive surgery, despite good corneal healing and negligible refractive error. We postulated that perceiving blur in the absence of refractive error or significant monocular aberrations might result from poor binocular control. Binocular vision testing in a series of such patients revealed convergence problems in 83% of cases. Case Reports: We report on 8 patients (average age 37.4 yrs who completed up to 40 sessions of vision therapy (VT, either completely via computer or in a combination of computer orthoptics and office vision therapy. Seven patients had received LASIK; one had PRK. Optometric measurements and symptoms were recorded before and after VT treatment, starting at least 3 months after refractive surgery. Near point of convergence improved in 7 cases following VT, and convergence break and/or recovery improved in 6 cases. Six cases reported symptom reduction, and pre-presbyopic cases tended to improve accommodative facility. The number of binocular functions showing improvement per case correlated with the number of VT sessions completed. Convergence changes were statistically significant when pre-/post-VT data were compared for these cases as a group. Conclusion: Patients complaining of distance blur following refractive surgery may have undiagnosed binocular vision problems. VT incorporating an internet orthoptics component improved convergence ability in the cases reported here, and most patients reported symptomatic relief.

  14. Geographical influences of an emerging network of gang rivalries

    Science.gov (United States)

    Hegemann, Rachel A.; Smith, Laura M.; Barbaro, Alethea B. T.; Bertozzi, Andrea L.; Reid, Shannon E.; Tita, George E.

    2011-10-01

    We propose an agent-based model to simulate the creation of street gang rivalries. The movement dynamics of agents are coupled to an evolving network of gang rivalries, which is determined by previous interactions among agents in the system. Basic gang data, geographic information, and behavioral dynamics suggested by the criminology literature are integrated into the model. The major highways, rivers, and the locations of gangs’ centers of activity influence the agents’ motion. We use a policing division of the Los Angeles Police Department as a case study to test our model. We apply common metrics from graph theory to analyze our model, comparing networks produced by our simulations and an instance of a Geographical Threshold Graph to the existing network from the criminology literature.

  15. Maintaining a suite of binocular facility instruments at the Large Binocular Telescope

    Science.gov (United States)

    Reynolds, Robert O.; Morris, John; Power, Jennifer; Howard, James; Riedl, James; Solheid, Elliott; Wagner, R. M.; Veillet, Christian

    2014-08-01

    Facility Instruments at the Large Binocular Telescope (LBT) include the Large Binocular Camera (LBC), a pair of wide-field imagers at the prime focus, the LUCIFER (or LUCI) near-infrared imager and spectrograph pair, and the Multi-Object Double Spectrograph (MODS), a pair of long-slit spectrographs. The disciplines involved in instrument support are reviewed, as well as scheduling of support personnel. A computerized system for instrument maintenance scheduling and spare parts inventory is described. Instrument problems are tracked via an online reporting system, and statistics on types of instrument problems are discussed, as well as applicability of the system to troubleshooting.

  16. The Effect of Competitive Rivalry on Internal Communication in Private Healthcare Organizations: Evidence from Istanbul, Turkey

    OpenAIRE

    Gültekin Altuntas; Fatih Semerciöz; Aral Noyan

    2014-01-01

    Both competitive rivalry and internal communication play a crucial role for a business to position itself in a favourable manner in order to succeed particularly in a hostile environment. While numerous studies present the importance of competitive rivalry and of communication, even internal communication separately, little is known about the specific linkage of how competitive rivalry affects communication in the literature. Within the framework of internal communication, this st...

  17. Attentional Switching in Humans and Flies: Rivalry in Large and Miniature Brains

    OpenAIRE

    Steven Mark Miller; Trung Thanh Ngo; Bruno evan Swinderen

    2012-01-01

    Human perception, and consequently behaviour, is driven by attention dynamics. In the special case of rivalry, where attention alternates between competing percepts, such dynamics can be measured and their determinants investigated. A recent study in the fruit fly, Drosophila melanogaster, now shows that the origins of attentional rivalry may be quite ancient. Furthermore, individual variation exists in the rate of attentional rivalry in both humans and flies, and in humans this is under subs...

  18. Team Learning: Through the Relational Dynamics of Co-operation and Rivalry in Team Communities

    OpenAIRE

    Lotz, Maja

    2008-01-01

    In this paper I explore the constructive links between co-operation, rivalry, and learning within the structure of team communities. Drawing upon social learning theory, the main purpose of this paper is to argue that both co-operation and rivalry are important triggers for mobilizing learning processes within and between teams. However, social learning theory tends to disregard the positive aspects of rivalry. Consequently, this paper will argue for the need to extend social learning theory ...

  19. Flexible Manufacturing Systems and the Effects to the Rivalry Power of the Companies.

    OpenAIRE

    SOBA, Mustafa

    2008-01-01

    In the rivalry conditions that change by means of globalization, it is needed that the companies have to perceive the changes rapidly and adapt with all of their functions. It is only possible by a flexible structure to perceive and adapt the change. Global developments have affected the rivalry components as rival, market, product, price etc. On the accounts of the companies and the concepts as market, rivalry, consumer, price, quality etc. have been transformed into global concepts from the...

  20. Ideal Binocular Disparity Detectors Learned Using Independent Subspace Analysis on Binocular Natural Image Pairs.

    Directory of Open Access Journals (Sweden)

    David W Hunter

    Full Text Available An influential theory of mammalian vision, known as the efficient coding hypothesis, holds that early stages in the visual cortex attempts to form an efficient coding of ecologically valid stimuli. Although numerous authors have successfully modelled some aspects of early vision mathematically, closer inspection has found substantial discrepancies between the predictions of some of these models and observations of neurons in the visual cortex. In particular analysis of linear-non-linear models of simple-cells using Independent Component Analysis has found a strong bias towards features on the horoptor. In order to investigate the link between the information content of binocular images, mathematical models of complex cells and physiological recordings, we applied Independent Subspace Analysis to binocular image patches in order to learn a set of complex-cell-like models. We found that these complex-cell-like models exhibited a wide range of binocular disparity-discriminability, although only a minority exhibited high binocular discrimination scores. However, in common with the linear-non-linear model case we found that feature detection was limited to the horoptor suggesting that current mathematical models are limited in their ability to explain the functionality of the visual cortex.

  1. Star formation: Sibling rivalry begins at birth

    Science.gov (United States)

    Kratter, Kaitlin M.

    2015-02-01

    High-resolution astronomical observations of a nearby molecular gas cloud have revealed a quadruplet of stars in the act of formation. The system is arguably the youngest multiple star system detected so far. See Letter p.213

  2. The Effects of Birth Order on Personality Traits and Feelings of Academic Sibling Rivalry

    Science.gov (United States)

    Badger, Julia; Reddy, Peter

    2009-01-01

    The influence of birth order on personality and sibling rivalry is controversial; little research has been conducted into academic sibling rivalry, and none into the connection with personality traits. This study considers the interaction of all three factors. Firstborns (N=22) and lastborns (N=24) completed online personality tests and an…

  3. Team Learning: Through the Relational Dynamics of Co-operation and Rivalry in Team Communities

    Science.gov (United States)

    Lotz, Maja

    2010-01-01

    This paper explores the constructive links between cooperation, rivalry, and learning within the structure of team communities. Drawing upon social learning theory and qualitative data from case studies conducted in Danish team-based firms, the main purpose is to argue that both cooperation and rivalry are important triggers for mobilizing…

  4. An analysis of intergroup rivalry using Ising model and reinforcement learning

    Science.gov (United States)

    Zhao, Feng-Fei; Qin, Zheng; Shao, Zhuo

    2014-01-01

    Modeling of intergroup rivalry can help us better understand economic competitions, political elections and other similar activities. The result of intergroup rivalry depends on the co-evolution of individual behavior within one group and the impact from the rival group. In this paper, we model the rivalry behavior using Ising model. Different from other simulation studies using Ising model, the evolution rules of each individual in our model are not static, but have the ability to learn from historical experience using reinforcement learning technique, which makes the simulation more close to real human behavior. We studied the phase transition in intergroup rivalry and focused on the impact of the degree of social freedom, the personality of group members and the social experience of individuals. The results of computer simulation show that a society with a low degree of social freedom and highly educated, experienced individuals is more likely to be one-sided in intergroup rivalry.

  5. Rivalry in the U.S. Airline Industry

    OpenAIRE

    Barla, Philippe

    1996-01-01

    In this paper, we use Market Share Instability (MSI) as a measure of the intensity of competition among airlines on a specific route. This measure is used to capture not only price competition but also non-price competition notably capacity competition. We test the effect of different variables (used in pricing studies) on MSI on a sample of 400 routes over the period 1987 to 1993. Most of the results found in pricing studies are confirmed using this measure of rivalry. For example the presen...

  6. Syria's predicament : state (de-) formation and international rivalries

    OpenAIRE

    Saouli, Adham

    2014-01-01

    Syria’s war raises important questions about the interaction between the domestic and external dimensions of the conflict. What are the main areas of contention, and how do they relate to regional and international dynamics? Why has the conflict developed into a regional and international battle, and who are the main actors in this rivalry? And, finally, what are the realistic options for ending the Syrian war? The aim of this paper is to answer these questions. In the first, the author exami...

  7. International R&D Rivalry with a Shipping Firm

    OpenAIRE

    Takauchi, Kazuhiro

    2012-01-01

    To examine the role of shipping firms in the international research and development (R&D) rivalry, we build a two-country (exporting and importing), two-firm (exporting and local) duopoly model with a shipping firm. The exporting firm competes with the local firm in the duopoly market of the local country but must pay a shipping fee to the shipping firm in order to sell its product in the local market. Similar to market competition, exporting and local firms engage in R&D competition. We comp...

  8. Sibling violence silenced: rivalry, competition, wrestling, playing, roughhousing, benign.

    Science.gov (United States)

    Phillips, Debby A; Phillips, Kate H; Grupp, Kitty; Trigg, Lisa J

    2009-01-01

    In this article, sibling violence and the silence surrounding it is explicated through professional literature and research findings, exemplars from clinical practice, and statistics. Theoretical positions and discourse analysis have been used to help explain how regular broken bones, bruises, lacerations, and verbal humiliation can be minimized as normal sibling rivalry or roughhousing, which does not cause serious consequences. Nursing should be on the front lines of ending practices of violence. Recognizing sibling violence as such is part of this work and is a social justice issue. PMID:19461218

  9. 3D Motion Parameters Determination Based on Binocular Sequence Images

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Exactly capturing three dimensional (3D) motion information of an object is an essential and important task in computer vision, and is also one of the most difficult problems. In this paper, a binocular vision system and a method for determining 3D motion parameters of an object from binocular sequence images are introduced. The main steps include camera calibration, the matching of motion and stereo images, 3D feature point correspondences and resolving the motion parameters. Finally, the experimental results of acquiring the motion parameters of the objects with uniform velocity and acceleration in the straight line based on the real binocular sequence images by the mentioned method are presented.

  10. Trinocular Calibration Method Based on Binocular Calibration

    Directory of Open Access Journals (Sweden)

    CAO Dan-Dan

    2012-10-01

    Full Text Available In order to solve the self-occlusion problem in plane-based multi-camera calibration system and expand the measurement range, a tri-camera vision system based on binocular calibration is proposed. The three cameras are grouped into two pairs, while the public camera is taken as the reference to build the global coordinate. By calibration of the measured absolute distance and the true absolute distance, global calibration is realized. The MRE (mean relative error of the global calibration of the two camera pairs in the experiments can be as low as 0.277% and 0.328% respectively. Experiment results show that this method is feasible, simple and effective, and has high precision.

  11. Future Hegemonic Rivalry Between China and the West?

    Directory of Open Access Journals (Sweden)

    Erich Weede

    1995-08-01

    Full Text Available Currently there is a unipolar distribution of power. The United States reigns supreme. Russia's economic power will remain insufficient to underwrite a renewed attempt to establish global leadership. While the European Community still commands sufficient resources for exercising global leadership, it lacks the political foundation for unitary action. Moreover, the European addiction to the welfare state undermines European competitiveness. Japan is too much of a "trading state" and unlikely to become a first-rate military power, before she is overtaken by China in economic size. So, count Russia, Europe and Japan out as conceivable challengers to United States hegemony. China is the only plausible candidate. Its economic growth rate is nothing less than spectacular. Moreover, the Chinese government seems capable of extracting the necessary resources for waging a hegemonic rivalry from a society that is likely to remain quite poor for at least another generation. There are a number of conceivable scenarios for the emerging American-Chinese relationship. The future will depend on the relative speed of the American decline and the rise of China as well as on the openness of the global economy. The more open the global economy, the better the prospects for rising per capita incomes in China become, the better the prospects for some mellowing or even democratization of the Chinese regime. Only if the West sticks together under American leadership and if creeping capitalism in China leads to creeping democratization later, is hegemonic rivalry likely to remain benign and peaceful.

  12. Practical considerations for pointing a binocular telescope

    Science.gov (United States)

    De La Peña, Michele D.; Terrett, David L.; Thompson, David; Biddick, Christopher J.

    2010-07-01

    The Large Binocular Telescope (LBT) consists of two 8.4-meter primary mirrors on a common mount. When the telescope is complete, to complement the two primaries there will be two 0.9-meter adaptive secondaries and two tertiary mirror flats that all work to support a variety of Gregorian focal stations, as well as prime focus. A fundamental goal of the telescope is to perform interferometric observations, and therefore, there is a critical need for the ability to co-point the individual telescopes to high precision. Further, a unique aspect of the LBT is the comparatively large range over which the optics can be adjusted which provides flexibility for the acquisition of targets. In the most general case, an observer could be performing an observation using different targets, within constraints, with different instruments on each of the two telescope sides, with different observing duty cycles. As a consequence of the binocular nature of the telescope and the number of possible observing combinations, there are unique requirements imposed on the Telescope Control System (TCS), and in particular, on the Pointing Control Subsystem (PCS). It is the responsibility of the PCS to arbitrate the pointing requests made on the two sides of the telescope by the observers, incorporate guide updates, and generate tracking trajectories for the mount and the rotators, in conjunction with providing tip/tilt demands on the subsystem controlling the optical elements, and ensure each target remains on the specified location (i.e., pointing origin) in the focal plane during an active observation. This paper describes the current design and implementation of the LBT PCS.

  13. THE TRIFID NEBULA: STELLAR SIBLING RIVALRY

    Science.gov (United States)

    2002-01-01

    This NASA Hubble Space Telescope image of the Trifid Nebula reveals a stellar nursery being torn apart by radiation from a nearby, massive star. The picture also provides a peek at embryonic stars forming within an ill-fated cloud of dust and gas, which is destined to be eaten away by the glare from the massive neighbor. This stellar activity is a beautiful example of how the life cycles of stars like our Sun is intimately connected with their more powerful siblings. The Hubble image shows a small part of a dense cloud of dust and gas, a stellar nursery full of embryonic stars. This cloud is about 8 light-years away from the nebula's central star, which is beyond the top of this picture. Located about 9,000 light-years from Earth, the Trifid resides in the constellation Sagittarius. A stellar jet [the thin, wispy object pointing to the upper left] protrudes from the head of a dense cloud and extends three-quarters of a light-year into the nebula. The jet's source is a very young stellar object that lies buried within the cloud. Jets such as this are the exhaust gases of star formation. Radiation from the massive star at the center of the nebula is making the gas in the jet glow, just as it causes the rest of the nebula to glow. The jet in the Trifid is a 'ticker tape,' telling the history of one particular young stellar object that is continuing to grow as its gravity draws in gas from its surroundings. But this particular ticker tape will not run for much longer. Within the next 10,000 years the glare from the central, massive star will continue to erode the nebula, overrunning the forming star, and bringing its growth to an abrupt and possibly premature end. Another nearby star may have already faced this fate. The Hubble picture shows a 'stalk' [the finger-like object] pointing from the head of the dense cloud directly toward the star that powers the Trifid. This stalk is a prominent example of the evaporating gaseous globules, or 'EGGs,' that were seen

  14. Symptomatology associated with accommodative and binocular vision anomalies

    OpenAIRE

    García Muñoz, Ángel; Carbonell-Bonete, Stela; Cacho Martínez, Pilar

    2014-01-01

    Purpose: To determine the symptoms associated with accommodative and non-strabismic binocular dysfunctions and to assess the methods used to obtain the subjects’ symptoms. Methods: We conducted a scoping review of articles published between 1988 and 2012 that analysed any aspect of the symptomatology associated with accommodative and non-strabismic binocular dysfunctions. The literature search was performed in Medline (PubMed), CINAHL, PsycINFO and FRANCIS. A total of 657 articles were identi...

  15. Perceptual constancy in judgments of egocentric distance: prevailing binocular information

    Directory of Open Access Journals (Sweden)

    Matsushima Elton H.

    2003-01-01

    Full Text Available Binocular cues were considered the prevailing information on specifying depth since the beginning of vision research. In the present study, two perceptual responses, the classical verbal report and a more recent method, open-loop walking, were used to assess the role of binocular information for egocentric distance perception. In two cue conditions environments, full- and reduced-cue, observers judged and walked egocentric distances of stimuli presented at eye-level, under binocular or monocular viewing. Results indicated perceptual constancy for open-loop walking and binocular responses, as well as poor performances under strong degradation on visual information (reduced-cue under monocular viewing, thus presenting evidence to support the fundamental role of binocular information on perception of egocentric distances. Besides that, visually directed actions could be adequate measures of perceived distance, with a better reliability than verbal report, since they were quite free of intrusion of inferential processes and perceptual tendencies. In addition, reduced head movements, side-to-side as well as back and forth deflexion movements, could have contributed to a near perfect coupling between binocular disparity information and open-loop walking responses.

  16. Effects of parietal TMS on somatosensory judgments challenge interhemispheric rivalry accounts

    OpenAIRE

    Eshel, N; Ruff, Christian C.; Spitzer, B; Blankenburg, F; Driver, J.

    2010-01-01

    Interplay between the cerebral hemispheres is vital for coordinating perception and behavior. One influential account holds that the hemispheres engage in rivalry, each inhibiting the other. In the somatosensory domain, a seminal paper claimed to demonstrate such interhemispheric rivalry, reporting improved tactile detection sensitivity on the right hand after transcranial magnetic stimulation (TMS) to the right parietal lobe (Seyal, Ro, & Rafal, 1995). Such improvement in tactile detection i...

  17. Barbara Fuchs & Emily Weissbourd (eds., Representing Imperial Rivalry in the Early Modern Mediterranean (Toronto: Toronto University Press, 2015

    Directory of Open Access Journals (Sweden)

    Viviana Tagliaferri

    2016-03-01

    Full Text Available Book review of: Barbara Fuchs, Emily Weissbourd (eds., Representing Imperial Rivalry in the Early Modern Mediterranean, (Toronto: Toronto University Press, 215, pp. 296, ISBN 9781442619272.

  18. ‘Proto-rivalry’: how the binocular brain identifies gloss

    Science.gov (United States)

    Muryy, Alexander A.; Welchman, Andrew E.

    2016-01-01

    Visually identifying glossy surfaces can be crucial for survival (e.g. ice patches on a road), yet estimating gloss is computationally challenging for both human and machine vision. Here, we demonstrate that human gloss perception exploits some surprisingly simple binocular fusion signals, which are likely available early in the visual cortex. In particular, we show that the unusual disparity gradients and vertical offsets produced by reflections create distinctive ‘proto-rivalrous’ (barely fusible) image regions that are a critical indicator of gloss. We find that manipulating the gradients and vertical components of binocular disparities yields predictable changes in material appearance. Removing or occluding proto-rivalrous signals makes surfaces look matte, while artificially adding such signals to images makes them appear glossy. This suggests that the human visual system has internalized the idiosyncratic binocular fusion characteristics of glossy surfaces, providing a straightforward means of estimating surface attributes using low-level image signals. PMID:27170713

  19. A new apparatus for visual field testing with binocular fixation

    Directory of Open Access Journals (Sweden)

    Hasegawa,Eiichi

    1978-07-01

    Full Text Available A new instrument for visual field examination with binocular fixation is described. The binocular vision was dissociated with polarizing plates. Only the point of fixation was visible to both eyes while the testing chart (Amsler chart was visible to one eye in the use of this apparatus. The examination was done with both the patient's eyes open. With the use of this apparatus, not only was the visual line fixed steadily in order to detect various changes of the central visual field due to maculopathy or optic neuropathy and these changes were detected accurately and quickly, but also suppression scotoma associated with amblyopia or squint could be detected quantitatively.

  20. Birth spacing, sibling rivalry and child mortality in India.

    Science.gov (United States)

    Whitworth, Alison; Stephenson, Rob

    2002-12-01

    The detrimental impact of short preceding birth intervals on infant and early childhood mortality is well documented in demographic literature, although the pathways of influence within the relationship remain an area of debate. This paper examines the impact of the length of the preceding birth interval on under-two mortality in India, and examines the pathways through which short preceding birth intervals may lead to an increased risk of mortality. Three mortality periods are examined: neonatal, early post neonatal and late post-neonatal and toddler, using the 1992 Indian National Family Health Survey. A multilevel modelling approach is used to account for the hierarchical nature of the data. The determinants of infants following a short or long birth interval are also examined. The results show that short preceding birth intervals (sibling rivalry is a pathway through which short birth intervals influence mortality, with the death of the previous sibling removing the competition for scarce resources, and resulting in lower risks of mortality than if the previous sibling was still alive. The greatest risks of an infant following a short birth interval are among those whose previous sibling died, high parities, those with young mothers, and those whose previous sibling was breastfed for a short duration. PMID:12409124

  1. Effects of parietal TMS on somatosensory judgments challenge interhemispheric rivalry accounts.

    Science.gov (United States)

    Eshel, Neir; Ruff, Christian C; Spitzer, Bernhard; Blankenburg, Felix; Driver, Jon

    2010-10-01

    Interplay between the cerebral hemispheres is vital for coordinating perception and behavior. One influential account holds that the hemispheres engage in rivalry, each inhibiting the other. In the somatosensory domain, a seminal paper claimed to demonstrate such interhemispheric rivalry, reporting improved tactile detection sensitivity on the right hand after transcranial magnetic stimulation (TMS) to the right parietal lobe (Seyal, Ro, & Rafal, 1995). Such improvement in tactile detection ipsilateral to TMS could follow from interhemispheric rivalry, if one assumes that TMS disrupted cortical processing under the coil and thereby released the other hemisphere from inhibition. Here we extended the study by Seyal et al. (1995) to determine the effects of right parietal TMS on tactile processing for either hand, rather than only the ipsilateral hand. We performed two experiments applying TMS in the context of median-nerve stimulation; one experiment required somatosensory detection, the second somatosensory intensity discrimination. We found different TMS effects on detection versus discrimination, but neither set of results followed the prediction from hemispheric rivalry that enhanced performance for one hand should invariably be associated with impaired performance for the other hand, and vice-versa. Our results argue against a strict rivalry interpretation, instead suggesting that parietal TMS can provide a pedestal-like increment in somatosensory response. PMID:20678510

  2. Sibling rivalry and the new baby: anticipatory guidance and management strategies.

    Science.gov (United States)

    Sawicki, J A

    1997-01-01

    Sibling rivalry can be found in many families and frequently creates a stressful and challenging situation for parents. The arrival of a new baby often causes older siblings to feel displaced, frustrated, angry, and even unloved. Age, gender, personality and temperament, and parental behavior are factors that appear to influence the degree to which sibling rivalry occurs. Common reactions of older siblings to the birth of a new baby include aggression toward the newborn, behavioral regression, and attention seeking behavior, as well as independence and maturity. Anticipatory guidance is recommended to help parents adequately prepare their older child for the arrival of a new sibling. Strategies for managing sibling rivalry include open parent-child communication, equal treatment of siblings, non-intervention in sibling conflicts, distraction, and separation. Parents can minimize feelings of jealousy between siblings by providing a supportive, nurturing environment that allows each child to feel secure and loved. PMID:9220807

  3. RIVALS OF A KIND: the Anglo-American Commercial Aviation Rivalry, 1939-45

    Directory of Open Access Journals (Sweden)

    Erik Benson

    2008-01-01

    Full Text Available Before World War II, the British and Americans had been fierce rivals in the international airline business. Their wartime alliance muted this rivalry, yet it still simmered, manifesting itself in a variety of global incidents and issues. As the war progressed, the Americans gained tremendous advantages in the field, raising British fears about American dominance of the world’s airways. In turn, American policymakers worried about British control of key areas of the world. The mutual suspicion grew, and the rivalry resurfaced in the last months of the war. The conflict had merely subsumed the differences, and made the two powers rivals of a kind.

  4. A deep Large Binocular Telescope view of the Canes Venatici I dwarf galaxy

    CERN Document Server

    Martin, Nicolas F; De Jong, Jelte T A; Rix, Hans-Walter; Bell, Eric F; Sand, David J; Hill, John M; Kochanek, Christopher S; Thompson, David; Burwitz, Vadim; Giallongo, Emanuele; Ragazzoni, Roberto; Diolaiti, Emiliano; Gasparo, Federico; Grazian, Andrea; Pedichini, Fernando; Bechtold, Jill

    2007-01-01

    We present the first deep color-magnitude diagram of the Canes Venatici I (CVnI) dwarf galaxy from observations with the wide field Large Binocular Camera of the Large Binocular Telescope. Reaching down to the main-sequence turnoff of the oldest stars, it reveals a dichotomy in the stellar populations of CVnI: it harbors an old (>~ 10 Gyr), metal-poor ([Fe/H] ~ -2.0) and spatially extended population along with a much younger (~1.4-2.0 Gyr), 0.5 dex more metal-rich, and spatially more concentrated population. These young stars are also offset by ~100 pc to the East of the center of the galaxy. The data suggest that this young population should be identified with the kinematically cold stellar component found by Ibata et al. (2006). CVnI therefore follows the behavior of the other remote MW dwarf spheroidals which all contain intermediate age and/or young populations: a complex star formation history is possible in extremely low-mass galaxies.

  5. Competition with and without priority control: linking rivalry to attention through winner-take-all networks with memory.

    Science.gov (United States)

    Marx, Svenja; Gruenhage, Gina; Walper, Daniel; Rutishauser, Ueli; Einhäuser, Wolfgang

    2015-03-01

    Competition is ubiquitous in perception. For example, items in the visual field compete for processing resources, and attention controls their priority (biased competition). The inevitable ambiguity in the interpretation of sensory signals yields another form of competition: distinct perceptual interpretations compete for access to awareness. Rivalry, where two equally likely percepts compete for dominance, explicates the latter form of competition. Building upon the similarity between attention and rivalry, we propose to model rivalry by a generic competitive circuit that is widely used in the attention literature-a winner-take-all (WTA) network. Specifically, we show that a network of two coupled WTA circuits replicates three common hallmarks of rivalry: the distribution of dominance durations, their dependence on input strength ("Levelt's propositions"), and the effects of stimulus removal (blanking). This model introduces a form of memory by forming discrete states and explains experimental data better than competitive models of rivalry without memory. This result supports the crucial role of memory in rivalry specifically and in competitive processes in general. Our approach unifies the seemingly distinct phenomena of rivalry, memory, and attention in a single model with competition as the common underlying principle. PMID:25581077

  6. Keeping School Sport Rivalries Respectful: In a Sports-Obsessed World

    Science.gov (United States)

    McCollum, Sean

    2012-01-01

    Great rivalries represent sports at their most dramatic. These contests and the histories behind them can inspire the best in athletes and bring together communities in shared enthusiasm like few other public events can. This is shown in venues large and small, from national pride during the Olympic Games to the community spirit on display when…

  7. Binocular disparity as an explanation for the moon illusion

    CERN Document Server

    Antonides, Joseph

    2013-01-01

    We present another explanation for the moon illusion, in which the moon looks larger near the horizon than near the zenith. In our model, the sky is considered a spatially contiguous and geometrically smooth surface. When an object (like the moon) breaks the contiguity of the surface, humans perceive an occlusion of the surface rather than an object appearing through a hole. Binocular vision dictates that the moon is distant, but this perception model dictates that the moon is closer than the sky. To solve the dilemma, the brain distorts the projections of the moon to increase the binocular disparity, which results in increase of the angular size of the moon. The degree of the distortion depends upon the apparent distance to the sky, which is influenced by the surrounding objects and the condition of the sky. The closer the sky appears, the stronger the illusion. At the zenith, few distance cues are present, causing difficulty with distance estimation and weakening the illusion.

  8. Standard Test Method for Measuring Binocular Disparity in Transparent Parts

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers the amount of binocular disparity that is induced by transparent parts such as aircraft windscreens, canopies, HUD combining glasses, visors, or goggles. This test method may be applied to parts of any size, shape, or thickness, individually or in combination, so as to determine the contribution of each transparent part to the overall binocular disparity present in the total “viewing system” being used by a human operator. 1.2 This test method represents one of several techniques that are available for measuring binocular disparity, but is the only technique that yields a quantitative figure of merit that can be related to operator visual performance. 1.3 This test method employs apparatus currently being used in the measurement of optical angular deviation under Method F 801. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not con...

  9. Binocular interactions underlying the classic optomotor responses of flying flies

    Directory of Open Access Journals (Sweden)

    Mark A Frye

    2012-02-01

    Full Text Available In response to imposed course deviations, the fast optomotor reactions of animals reduce motion blur and facilitate the maintenance of stable body posture. In flies, the monocular front-to-back (progressive and back-to-front (regressive visual motion components generated by horizontal rotation are selectively encoded, respectively, by homo and heterolateral motion sensitive circuits in the third optic ganglion, the lobula plate. To investigate the strength of such inter-ocular interactions and their role in compensatory sensory-motor transformations, we utilize a virtual reality flight simulator to record optomotor reactions by tethered flying flies in response to imposed binocular and monocular visual rotation. With stimulus parameters generating large contrast insensitive optomotor responses to binocular rotation, we find that responses to monocular progressive motion are larger than those to panoramic rotation but contrast sensitive. Conversely, responses to monocular regressive motion are slower than those to rotation and peak at the lowest tested contrast. Together our results suggest that contrast insensitive optomotor responses to binocular rotation result from the dynamic interplay of contralateral inhibitory as well as excitatory circuit interactions and serve to maintain a stable optomotor equilibrium across a range of visual contrasts.

  10. A Standardized Procedure and Normative Values for Measuring Binocular Dynamic Visual Acuity

    OpenAIRE

    Amanda Miskewicz-Zastrow, OD; Eric Bishop, OD; Alan Zastrow, OD; Dan Mark Cuevas, OD; Bill B. Rainey, OD, MS

    2015-01-01

    Background: Binocular dynamic visual acuity (BDVA) is the ability to differentiate fine details in a moving object such as seams on a pitched baseball or the rotation of a tennis ball, both of which can travel up to speeds exceeding 100 miles per hour. BDVA is one of many binocular visual measurements to examine binocular function. This study was designed to provide a standardized procedure for measuring BDVA and normal values for a sample population. Previous studies have used different t...

  11. Anomalies of binocular function in patients with longstanding asymmetric keratoconus

    OpenAIRE

    Sherafat, H; White, J; Pullum, K.; Adams, G; Sloper, J.

    2001-01-01

    AIMS—To study binocular function in patients with longstanding asymmetric keratoconus.
METHODS—In 20 adult patients with longstanding asymmetric keratoconus managed with a scleral contact lens a full clinical and orthoptic assessment was performed with and without the scleral contact lens in the poorer eye.
RESULTS—All 20 patients had a corrected acuity of at least 6/9 in their better eye. With the scleral lens in situ the acuity of the poorer eye ranged from 6/6 to 6/60 and without the lens ...

  12. An automated miniaturized Haploscope for testing binocular visual function

    Science.gov (United States)

    Decker, T. A.; Williams, R. E.; Kuether, C. L.; Wyman-Cornsweet, D.

    1976-01-01

    A computer-controlled binocular vision testing device has been developed as one part of a system designed for NASA to test the vision of astronauts during spaceflight. The device, called the Mark III Haploscope, utilizes semi-automated psychophysical test procedures to measure visual acuity, stereopsis, phorias, fixation disparity and accommodation/convergence relationships. All tests are self-administered, yield quantitative data and may be used repeatedly without subject memorization. Future applications of this programmable, compact device include its use as a clinical instrument to perform routine eye examinations or vision screening, and as a research tool to examine the effects of environment or work-cycle upon visual function.

  13. A Buyer's and User's Guide to Astronomical Telescopes and Binoculars

    Science.gov (United States)

    Mullaney, James

    This book is offered as a no-nonsense practical guide to the selection and use of telescopes and binoculars for stargazing. But these devices should not be looked upon as yet more gadgets to add to our collection of modern technical possessions. Rightly viewed, they are truly magical instruments, for they are literally "spaceships of the mind," "time machines," and "windows on creation" that allow their users to roam the universe in what is surely the next best thing to actually being there!

  14. RIVALS OF A KIND: the Anglo-American Commercial Aviation Rivalry, 1939-45

    OpenAIRE

    Erik Benson

    2008-01-01

    Before World War II, the British and Americans had been fierce rivals in the international airline business. Their wartime alliance muted this rivalry, yet it still simmered, manifesting itself in a variety of global incidents and issues. As the war progressed, the Americans gained tremendous advantages in the field, raising British fears about American dominance of the world’s airways. In turn, American policymakers worried about British control of key areas of the world. The mutual suspicio...

  15. Sibling rivalry and the gender gap: Evidence from child health outcomes in Ghana

    OpenAIRE

    Ashish Garg; Jonathan Morduch

    1998-01-01

    When capital and labor markets are imperfect, choice sets narrow, and parents must choose how to ration available funds and time between their children. One consequence is that children become rivals for household resources. In economies with pro-male bias, such rivalries can yield gains to having relatively more sisters than brothers. Using a rich household survey from Ghana, we find that on average if children had all sisters (and no brothers) they would do roughly 25-40% better on measured...

  16. Brand rivalry, market segmentation and the pricing of optional engine power on automobiles

    OpenAIRE

    Verboven, Frank

    1996-01-01

    This paper analyzes how the prices strategies for base automobile models may differ from those for premium models, sold with extra engine power. The popular monopoly model of market segmentation according to willingness to pay for quality is compared with two models of brand rivalry. In a first scenario, consumer are fully informed of all prices; in a second scenario, consumers are initially only informed about the prices of base models , due to selective price advertising strategies. Impli...

  17. Evaluation of Binocular Vision Therapy Efficacy by 3D Video-Oculography Measurement of Binocular Alignment and Motility

    OpenAIRE

    Laria Ochaíta, Carlos; Piñero Llorens, David Pablo

    2013-01-01

    Objective: To evaluate two cases of intermittent exotropia (IX(T)) treated by vision therapy the efficacy of the treatment by complementing the clinical examination with a 3-D video-oculography to register and to evidence the potential applicability of this technology for such purpose. Methods: We report the binocular alignment changes occurring after vision therapy in a woman of 36 years with an IX(T) of 25 prism diopters (Δ) at far and 18 Δ at near and a child of 10 years with 8 Δ of IX(T) ...

  18. Status and Plans for the Large Binocular Telescope

    Science.gov (United States)

    Green, R. F.

    2006-08-01

    The Large Binocular Telescope (LBT) is in commissioning, with the initiation of science operations planned for 2007. The telescope contains two 8.4-m diameter borosilicate honeycomb primary mirrors, supported actively to control bending modes. The secondary mirrors will provide adaptive optics correction through rapid modulation of the surface of a Zerodur face sheet 91 cm in diameter and 1.5 mm thick. The initial complement of facility instruments comprises capabilities used in pairs on common fields of view. The Large Binocular Cameras are wide-field 36 Mpix mosaics at prime focus optimized for blue and for red performance. The Multi-Object Double Spectrographs will be fed at straight-through Gregorian foci through custom cut focal plane masks. The ambitious LUCIFER near-IR spectrographs at bent Gregorian will have exchangeable cold focal plan masks. Ultimately, two instruments will combine the two beams through Fizeau interferometry. One, LBTI, is optimized for mid-IR, and will have a nulling capability for coronagraphic work. The other, LINC-NIRVANA, will employ three levels of adaptive correction to achieve interferometric resolution down to 1 micron. The 23-m tip-to-tip dimension affords resolution as good as 10 mas. LBTO is supported by a consortium of institutions from Arizona, Italy, Germany, and the U.S. It is truly an international project and the first of the next generation of large ground-based telescopes.

  19. The last will and testament in literature: rupture, rivalry, and sometimes rapprochement from Middlemarch to Lemony Snicket.

    Science.gov (United States)

    Stone, Elizabeth

    2008-12-01

    Although the psychological literature on the last will and testament is sparse, authors of fiction and memoir have filled the gap, writing in rich detail about the impact of wills on families. Henry James, George Eliot, J. R. Ackerley, and others reveal that a will is not only a legal document but a microcosm of family life: a coded and non-negotiable message from the will's writer to its intended readers, the heirs, delivered at a stressful time and driving home the truth that options for discussion between testator and heirs are now gone, all factors which may intensify the ambivalence of grief and stall its resolution. Among the problems the authors chronicle: reinvigorated sibling rivalries, vindictive testators, and the revelation of traumatic family secrets. Writers also demonstrate how contemporary social factors, such as divorce, second families, and geographic distance between family members, may complicate wills and ensuing family relations. Exemplary wills, or will-like documents, appear in fiction by Maria Katzenbach and Marilynne Robinson, allowing the living to make rapprochements with the dead, and pointing to testamentary strategies clinicians might develop to lead to a resolution of grief. The depth of these writers' accounts allows clinicians to imagine points at which they might productively intervene in matters pertaining to a will. PMID:19130785

  20. Uranium wars the scientific rivalry that created the nuclear age

    CERN Document Server

    Aczel, Amir D

    2009-01-01

    The author of Fermat's Last Theorem tackles the cause of the last century's most destructive event - the discovery of nuclear power. Aczel presents the fascinating story of the rival scientists who uncovered uranium's potential and reveals the ongoing tale of an element that is never far from today's headlines.

  1. A Novel Approach to Calibrating Multifunctional Binocular Stereovision Sensor

    International Nuclear Information System (INIS)

    We present a novel multifunctional binocular stereovision sensor for various threedimensional (3D) inspection tasks. It not only avoids the so-called correspondence problem of passive stereo vision, but also possesses the uniform mathematical model. We also propose a novel approach to estimating all the sensor parameters with free-position planar reference object. In this technique, the planar pattern can be moved freely by hand. All the camera intrinsic and extrinsic parameters with coefficient of lens radial and tangential distortion are estimated, and sensor parameters are calibrated based on the 3D measurement model and optimized with the feature point constraint algorithm using the same views in the camera calibration stage. The proposed approach greatly reduces the cost of the calibration equipment, and it is flexible and practical for the vision measurement. It shows that this method has high precision by experiment, and the sensor measured relative error of space length excels 0.3%

  2. Effect of firefighter masks on monocular and binocular peripheral vision.

    Science.gov (United States)

    Samo, Daniel G; Bahk, Jane K; Gerkin, Richard D

    2003-04-01

    Peripheral vision can impact essential job functions of firefighters and other workers who use Self-Contained Breathing Apparatus and other full face masks. It is important for physicians to know how these masks alter peripheral vision. Also, one must understand the effect of monocular vision on peripheral vision. Using the Goldman Perimeter Machine we measured peripheral vision in the monocular and binocular state, with and without two different types of masks. The results show that monocularity causes an average loss of 23 degrees in the nasal meridian. The use of the masks did not affect this difference. Also, the masks caused an average loss of 28 degrees of peripheral vision in the inferior meridian. How these losses affect the ability of the users of the masks to perform their essential job functions still needs to be researched. PMID:12708146

  3. Origins of strabismus and loss of binocular vision

    Directory of Open Access Journals (Sweden)

    Emmanuel Bui Quoc

    2014-09-01

    Full Text Available Strabismus is a frequent ocular disorder that develops early in life in humans. As a general rule, it is characterized by a misalignment of the visual axes which most often appears during the critical period of visual development. However other characteristics of strabismus may vary greatly among subjects, for example, being convergent or divergent, horizontal or vertical, with variable angles of deviation. Binocular vision may also vary greatly. Our main goal here is to develop the idea that such “polymorphy” reflects a wide variety in the possible origins of strabismus. We propose that strabismus must be considered as possibly resulting from abnormal genetic and/or acquired factors, anatomical and/or functional abnormalities, in the sensory and/or the motor systems, both peripherally and/or in the brain itself. We shall particularly develop the possible “central” origins of strabismus. Indeed, we are convinced that it is time now to open this “black box” in order to move forward. All of this will be developed on the basis of both presently available data in literature (including most recent data and our own experience. Both data in medicine and biology will be referred to. Our conclusions will hopefully help ophthalmologists to better understand strabismus and to develop new therapeutic strategies in the future. Presently, physicians eliminate or limit the negative effects of such pathology both on the development of the visual system and visual perception through the use of optical correction and, in some cases, extraocular muscle surgery. To better circumscribe the problem of the origins of strabismus, including at a cerebral level, may improve its management, in particular with respect to binocular vision, through innovating tools by treating the pathology at the source.

  4. Robust Active Binocular Vision through Intrinsically Motivated Learning

    Directory of Open Access Journals (Sweden)

    Luca eLonini

    2013-11-01

    Full Text Available The efficient coding hypothesis posits that sensory systems of animals strive to encode sensory signals efficiently by taking into account the redundancies in them. This principle has been very successful in explaining response properties of visual sensory neurons as adaptations to the statistics of natural images. Recently, we have begun to extend the efficient coding hypothesis to active perception through a form of intrinsically motivated learning: a sensory model learns an efficient code for the sensory signals while a reinforcement learner generates movements of the sense organs to improve the encoding of the signals. To this end, it receives an intrinsically generated reinforcement signal indicating how well the sensory model encodes the data. This approach has been tested in the context of binocular vison, leading to the autonomous development of disparity tuning and vergence control. Here we systematically investigate the robustness of the new approach in the context of a binocular vision system implemented on a robot. Robustness is an important aspect that reflects the ability of the system to deal with unmodeled disturbances or events, such as an insult to the system that displace the stereo cameras. To demonstrate the robustness of our method and its ability to self-calibrate, we introduce various perturbations and test if and how the system recovers from them. We find that 1 the system can fully recover from a perturbation that can be compensated through the system's motor degrees of freedom, 2 performance degrades gracefully if the system cannot use its motor degrees of freedom to compensate for the perturbation, and 3 recovery from a perturbation is improved if both the sensory encoding and the behavior policy can adapt to the perturbation. Overall, this work demonstrates that our intrinsically motivated learning approach for efficient coding in active perception gives rise to a self-calibrating perceptual system of high robustness.

  5. Robust active binocular vision through intrinsically motivated learning.

    Science.gov (United States)

    Lonini, Luca; Forestier, Sébastien; Teulière, Céline; Zhao, Yu; Shi, Bertram E; Triesch, Jochen

    2013-01-01

    The efficient coding hypothesis posits that sensory systems of animals strive to encode sensory signals efficiently by taking into account the redundancies in them. This principle has been very successful in explaining response properties of visual sensory neurons as adaptations to the statistics of natural images. Recently, we have begun to extend the efficient coding hypothesis to active perception through a form of intrinsically motivated learning: a sensory model learns an efficient code for the sensory signals while a reinforcement learner generates movements of the sense organs to improve the encoding of the signals. To this end, it receives an intrinsically generated reinforcement signal indicating how well the sensory model encodes the data. This approach has been tested in the context of binocular vison, leading to the autonomous development of disparity tuning and vergence control. Here we systematically investigate the robustness of the new approach in the context of a binocular vision system implemented on a robot. Robustness is an important aspect that reflects the ability of the system to deal with unmodeled disturbances or events, such as insults to the system that displace the stereo cameras. To demonstrate the robustness of our method and its ability to self-calibrate, we introduce various perturbations and test if and how the system recovers from them. We find that (1) the system can fully recover from a perturbation that can be compensated through the system's motor degrees of freedom, (2) performance degrades gracefully if the system cannot use its motor degrees of freedom to compensate for the perturbation, and (3) recovery from a perturbation is improved if both the sensory encoding and the behavior policy can adapt to the perturbation. Overall, this work demonstrates that our intrinsically motivated learning approach for efficient coding in active perception gives rise to a self-calibrating perceptual system of high robustness. PMID:24223552

  6. An overview of instrumentation for the Large Binocular Telescope

    Science.gov (United States)

    Wagner, R. Mark

    2010-07-01

    An overview of instrumentation for the Large Binocular Telescope is presented. Optical instrumentation includes the Large Binocular Camera (LBC), a pair of wide-field (27 × 27) mosaic CCD imagers at the prime focus, and the Multi-Object Double Spectrograph (MODS), a pair of dual-beam blue-red optimized long-slit spectrographs mounted at the straight-through F/15 Gregorian focus incorporating multiple slit masks for multi-object spectroscopy over a 6 field and spectral resolutions of up to 8000. Infrared instrumentation includes the LBT Near-IR Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research (LUCIFER), a modular near-infrared (0.9-2.5 μm) imager and spectrograph pair mounted at a bent interior focal station and designed for seeing-limited (FOV: 4 × 4) imaging, long-slit spectroscopy, and multi-object spectroscopy utilizing cooled slit masks and diffraction limited (FOV: 0.5 × 0.5) imaging and long-slit spectroscopy. Strategic instruments under development for the remaining two combined focal stations include an interferometric cryogenic beam combiner with near-infrared and thermal-infrared instruments for Fizeau imaging and nulling interferometry (LBTI) and an optical bench near-infrared beam combiner utilizing multi-conjugate adaptive optics for high angular resolution and sensitivity (LINC-NIRVANA). In addition, a fiber-fed bench spectrograph (PEPSI) capable of ultra high resolution spectroscopy and spectropolarimetry (R = 40,000-300,000) will be available as a principal investigator instrument. The availability of all these instruments mounted simultaneously on the LBT permits unique science, flexible scheduling, and improved operational support. Over the past two years the LBC and the first LUCIFER instrument have been brought into routine scientific operation and MODS1 commissioning is set to begin in the fall of 2010.

  7. Brood division in birds in relation to offspring size: sibling rivalry and parental control

    Science.gov (United States)

    Slagsvold

    1997-12-01

    In some altricial birds with biparental care, it is the female, and in others the male, that provides more food to the smallest offspring within the brood. Many hypotheses have been proposed to account for such puzzling patterns of parental care. A parsimonious explanation is that no difference exists between the parents in priority of care but that differences arise simply from sibling rivalry, with dominant chicks trying to position themselves closest to the parent that provides most care (the sibling rivalry hypothesis). A refinement of the idea is that parents use the way they approach the chicks to counter selfish offspring and in this way control allocation of care (the parental approaching hypothesis). A comparison across species suggested that female care of the smallest chick within a brood is the ancestral and most common pattern. However, strong variation exists within single populations. In one species, the American robin, Turdus migratorius the sibling rivalry hypothesis and the parental approaching hypothesis were both supported because in broods where males provided more care than females, the largest chick was predominantly fed by the male whereas the smallest chick was predominantly fed by the female. When the male provided less care than the female, an opposite result was found. The same patterns of allocation of care also seemed to exist when chicks were quite immobile just after having left the nest and when their positions were experimentally controlled, suggesting parental control.Copyright 1997 The Association for the Study of Animal BehaviourCopyright 1997The Association for the Study of Animal Behaviour. PMID:9521793

  8. Low-Cost Entry, Inter-Firm Rivalry, and Welfare Implications in US Large Air Markets

    OpenAIRE

    Hideki Murakami

    2009-01-01

    This paper empirically analyses the patterns of inter-firm rivalry between low-cost and full service carriers by carrier and airport bases, and demonstrate welfare implication of LCC, using 1163 US cross-sectional data of 1998 when LCCs were purely no-frilled carriers. Our main findings are: (1) that both LCC and full service carriers keep higher price-cost margins when LCCs enter in the secondary airport, while especially full service carriers suffer from low price-cost margin when LCCs ente...

  9. [Sibling relations from the family therapy perspective--support, attachment, rivalry and envy].

    Science.gov (United States)

    Cierpka, M

    2001-01-01

    In family therapy, during the last years more and more importance is attached to the dynamics of the sibling subsystem. In the present paper differences between them as well as similarities are discussed from the point of view of family theory. Relevant dimensions like support, attachment, rivalry and envy between brothers and sisters contribute essentially to the family dynamics. In this clinically orientated paper, we describe by means of a case example how the couple's conflicts after their separation is unconsciously repeated in the sibling subsystem. It is shown how the intergenerational dynamics can be interrupted by the initiative of the children and the initiated family therapy. PMID:11515394

  10. Sibling rivalry and the gender gap: evidence from child health outcomes in Ghana.

    Science.gov (United States)

    Garg, A; Morduch, J

    1998-01-01

    "When capital and labor markets are imperfect, choice sets narrow, and parents must choose how to ration available funds and time between their children. One consequence is that children become rivals for household resources. In economies with pro-male bias, such rivalries can yield gains to having relatively more sisters than brothers. Using a rich household survey from Ghana [the 1988-1989 Ghana Living Standards Survey], we find that on average if children had all sisters (and no brothers) they would do roughly 25-40% better on measured health indicators than if they had all brothers (and no sisters)." PMID:12294784

  11. UNFAIR COMPETITION? AMERICAN AND JAPANESE AIRLINES TRANSPACIFIC ROUTE RIVALRIES, 1946—1971

    Directory of Open Access Journals (Sweden)

    Douglas Karsner

    2007-01-01

    Full Text Available This article examines the changing nature of competition between American and Japanese airlines for transpacific passenger and cargo routes during the formative early postwar era. It focuses on the period from 1946, when the US government first certified Northwest and Pan American airlines to fly to Japan, to 1971, as the age of mass air travel took off amidst major economic changes such as the Nixon Shocks. Utilizing both American and Japanese sources, the author argues that a complex mixture of economic and diplomatic factors shaped American and Japanese airlines’ transpacific route rivalries.

  12. 'Indirect' symbolic violence and rivalry between equals in rural Punjab, Pakistan.

    OpenAIRE

    Lyon, S.M.

    2004-01-01

    This paper examines the social impact of the rice distribution ritual called a dég, in Punjab, Pakistan. This ritual exposes modes of dominance expressed or asserted by `symbolically' violent means. I focus on one dég which was significant by its excess, providing a clear example of the roles of the `giver', the `receiver' and the rivalries between collateral groups. Bourdieu's notions of symbolic violence provide one analytical social model of a mode of domination. This paper is not a refuta...

  13. The role of binocular disparity in rapid scene and pattern recognition

    OpenAIRE

    Valsecchi, M.; Caziot, B.; Backus, B. T.; Gegenfurtner, K. R.

    2013-01-01

    We investigated the contribution of binocular disparity to the rapid recognition of scenes and simpler spatial patterns using a paradigm combining backward masked stimulus presentation and short-term match-to-sample recognition. First, we showed that binocular disparity did not contribute significantly to the recognition of briefly presented natural and artificial scenes, even when the availability of monocular cues was reduced. Subsequently, using dense random dot stereograms as stimuli, we ...

  14. Rapid plasticity of binocular connections in developing monkey visual cortex (V1)

    OpenAIRE

    Zhang, Bin; Bi, Hua; Sakai, Eiichi; Maruko, Ichiro; Zheng, Jianghe; Smith, Earl L.; Chino, Yuzo M.

    2005-01-01

    The basic sets of cortical connections are present at birth in the primate visual system. The maintenance and refinement of these innate connections are highly dependent on normal visual experience, and prolonged exposure to binocularly uncorrelated signals early in life severely disrupts the normal development of binocular functions. However, very little is known about how rapidly these changes in the functional organization of primate visual cortex emerge or what are the sequence and the na...

  15. Effect of Near Work on Binocular Vision Measurements in Adults with Convergence Insufficiency

    OpenAIRE

    Yi Pang, OD, PhD; Helen Gabriel, OD; Kelly A. Frantz, OD

    2015-01-01

    Background: Convergence insufficiency (CI) is a common binocular vision disorder. A common characteristic of CI is that patients have more symptoms, such as eyestrain and headache, after close work. The purpose of this study was to determine whether 30 minutes of reading affects the binocular and accommodative measurements used in the diagnosis of CI. Methods: Eighteen normal adult subjects and eighteen adult CI subjects (symptomatic and asymptomatic) were recruited. None of the CI subjec...

  16. The relationship between binocular vision symptoms and near point of convergence

    OpenAIRE

    Momeni-Moghaddam Hamed; A Goss David; Ehsani Marzieh

    2013-01-01

    Aim and Background: Due to the relatively high prevalence of binocular vision anomalies, a regular examination including tests for assessment and determination of these anomalies is necessary. The aim of this study was to assess the relationship between near point of convergence (NPC) and near binocular vision symptoms and finding of an NPC cutoff point for symptoms in university students. Materials and Methods: In this cross-sectional study, 124 students of different majors of Zahedan Univer...

  17. Problems with balance and binocular visual dysfunction are associated with post-stroke fatigue

    DEFF Research Database (Denmark)

    Schow, Trine; Teasdale, Thomas William; Jensen Quas, Kirsten;

    2016-01-01

    Trine Schow, Thomas William Teasdale, Kirsten Jensen Quas& Morten Arendt Rasmussen (2016): Problems with balance and binocular visual dysfunction are associated with post-stroke fatigue, Topics in Stroke Rehabilitation, DOI: 10.1080/10749357.2016.1188475......Trine Schow, Thomas William Teasdale, Kirsten Jensen Quas& Morten Arendt Rasmussen (2016): Problems with balance and binocular visual dysfunction are associated with post-stroke fatigue, Topics in Stroke Rehabilitation, DOI: 10.1080/10749357.2016.1188475...

  18. Attachment and sibling rivalry in Little Hans: the fantasy of the two giraffes revisited.

    Science.gov (United States)

    Wakefield, Jerome C

    2007-01-01

    Freud's interpretation of Little Hans's "phantasy of the two giraffes" is pivotal to his oedipal analysis that Hans has inchoate desires for sexual intercourse with his mother. Bowlby argued that Freud's focus on his oedipal theory led him to ignore preoedipal attachment-related factors that have equal plausibility in explaining the clinical data. However, Bowlby did not attempt to apply the attachment perspective to the interpretation of Hans's fantasies that form the core of the case material. A microanalysis of Hans's giraffe fantasy and the evidence used to support Freud's claims about it yields an attachment-based sibling rivalry account arguably of greater explanatory power than the oedipal account. Consistent with Bowlby's hypothesis, the evidence suggests that Hans's giraffe fantasy is about the sibling rivalry triangle involved in caregiver attachment access, rather than (or in addition to) the oedipal triangle. The issue of multiple levels of meaning and the methodological challenges raised by multiple determination is also considered. The giraffe fantasy's attachment-theoretic explanation encourages a rethinking of this classic case and strengthens Bowlby's claim that the case is fruitfully viewed from an attachment perspective. PMID:17915649

  19. Three Logics of "Major Power Rivalry" in the World-System: A Footnote to a Pentagon study

    Directory of Open Access Journals (Sweden)

    Tieting Su

    1995-08-01

    Full Text Available A vast body of social science literature on long waves and major power wars has greatly enriched our knowledge about the rhythms and violent transitions of the modern world-system. The correlations between long waves and major power clashes in the past has been established. What are the structural causal mechanisms between these two historical and cyclical movements? Using trade network patterns as an indicator of a deep structure, this article summarizes a longitudinial study attempted to construct one of the missing links between the two historical cycles. Based on a structural analysis of world trade networks in 1938, 1950, and 1990, and a quantitative study of U.S.--Japanese commercial rivalry in the Asia-Pacific region, this study considers three logics of "major power rivalry" in the past and its implication for the future: (1 the logic of rivalry over "life spaces"; (2 the logic of rivalry for global domination; and (3 the logic of imperial intervention. I contend that these three logics are related, and that changes in one logic result in changes in others.

  20. EXO-ZODI MODELING FOR THE LARGE BINOCULAR TELESCOPE INTERFEROMETER

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, Grant M.; Wyatt, Mark C.; Panić, Olja; Shannon, Andrew [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Bailey, Vanessa; Defrère, Denis; Hinz, Philip M.; Rieke, George H.; Skemer, Andrew J.; Su, Katherine Y. L. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Bryden, Geoffrey; Mennesson, Bertrand; Morales, Farisa; Serabyn, Eugene [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Danchi, William C.; Roberge, Aki; Stapelfeldt, Karl R. [NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics, Code 667, Greenbelt, MD 20771 (United States); Haniff, Chris [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Lebreton, Jérémy [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Millan-Gabet, Rafael [NASA Exoplanet Science Institute, California Institute of Technology, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); and others

    2015-02-01

    Habitable zone dust levels are a key unknown that must be understood to ensure the success of future space missions to image Earth analogs around nearby stars. Current detection limits are several orders of magnitude above the level of the solar system's zodiacal cloud, so characterization of the brightness distribution of exo-zodi down to much fainter levels is needed. To this end, the Large Binocular Telescope Interferometer (LBTI) will detect thermal emission from habitable zone exo-zodi a few times brighter than solar system levels. Here we present a modeling framework for interpreting LBTI observations, which yields dust levels from detections and upper limits that are then converted into predictions and upper limits for the scattered light surface brightness. We apply this model to the HOSTS survey sample of nearby stars; assuming a null depth uncertainty of 10{sup –4} the LBTI will be sensitive to dust a few times above the solar system level around Sun-like stars, and to even lower dust levels for more massive stars.

  1. A buyer's and user's guide to astronomical telescopes and binoculars

    CERN Document Server

    Mullaney, James

    2014-01-01

    Amateur astronomers of all skill levels are always contemplating their next telescope, and this book points the way to the most suitable instruments. Similarly, those who are buying their first telescopes – and these days not necessarily a low-cost one – will be able to compare and contrast different types and manufacturers. This revised new guide provides an extensive overview of binoculars and telescopes. It includes detailed up-to-date information on sources, selection and use of virtually every major type, brand, and model on today’s market, a truly invaluable treasure-trove of information and helpful advice for all amateur astronomers. Originally written in 2006, much of the first edition is inevitably now out of date, as equipment advances and manufacturers come and go. This second edition not only updates all the existing sections but adds two new ones: Astro-imaging and Professional-Amateur collaboration. Thanks to the rapid and amazing developments that have been made in digital cameras it is...

  2. EXO-ZODI MODELING FOR THE LARGE BINOCULAR TELESCOPE INTERFEROMETER

    International Nuclear Information System (INIS)

    Habitable zone dust levels are a key unknown that must be understood to ensure the success of future space missions to image Earth analogs around nearby stars. Current detection limits are several orders of magnitude above the level of the solar system's zodiacal cloud, so characterization of the brightness distribution of exo-zodi down to much fainter levels is needed. To this end, the Large Binocular Telescope Interferometer (LBTI) will detect thermal emission from habitable zone exo-zodi a few times brighter than solar system levels. Here we present a modeling framework for interpreting LBTI observations, which yields dust levels from detections and upper limits that are then converted into predictions and upper limits for the scattered light surface brightness. We apply this model to the HOSTS survey sample of nearby stars; assuming a null depth uncertainty of 10–4 the LBTI will be sensitive to dust a few times above the solar system level around Sun-like stars, and to even lower dust levels for more massive stars

  3. Sinusoidal calibration technique for Large Binocular Telescope system

    Science.gov (United States)

    Pieralli, F.; Puglisi, A.; Quiros Pacheco, F.; Esposito, S.

    2008-07-01

    Telescopes of 8 meter class, like Large Binocular Telescope (LBT), are based on the concept of Deformable Secondary Mirror (DSM); in order to calculate the best DSM shape that correct the measured aberrations we need to calibrate the AO system, so we need a correlation between the DSM and the wave front sensor (WFS), i.e. we need the Interaction Matrix (IM). Usually we obtain the IM in laboratory or at the telescope using as source a reference fiber that illuminates both the deformable mirror and wave front sensor. But in case of LBT and all large telescopes, this technique can be very difficult or sometimes impossible, and calibration may be required to be performed on sky. So we need new calibration techniques, and we investigate about sinusoidal modulation one for LBT case. In the Arcetri solar tower (inside Arcetri Observatory) we recreated a set up environment similar to the telescope, and thanks to that we can test the calibration system in the same condition of the LBT. In preparation for the test some simulations of this sinusoidal modulation technique were needed, in order to choose the best parameters that increased SNR and reduced integration time. The paper will detail the simulation results of the calibration LBT system made with this new technique, and these results will be used to drive our tests in the tower.

  4. Sibling rivalry

    OpenAIRE

    Mark Miodownik

    2005-01-01

    The developments being made on varius uses of the titanium and titania are discussed. It can be used in jet engines because of its steel like strength and immunity towards environmental attacks. It can be used in world's most avante-garde buildings and is ideal for body piercing due to its corrosion resistance properties. A new titanium extraction process invented by the University of Cambridge for the production of oxygen on the moon surface is also discussed.

  5. [Binocular photometer for measuring light perception in diseases of the visual pathway].

    Science.gov (United States)

    Stave, J; Guthoff, R

    1995-04-01

    In patients with a reduction in visual function because of optic nerve neuritis, light sensitivity is tested to detect differences between the right and left eye in combination with the swinging flashlight test and visual evoked potential (VEP). A binocular Zeiss microscope was modified to use integrated photometer-controlled binocular stimulus fields and a central light system for fixation and variation of the contrast (background illumination). For exact binocular measurements of light sensitivity on both eyes, electronically controlled test fields (visual angle 5 degrees-20 degrees) guarantees only macular or overfoveolar stimulation. In addition, splitting the light for each stimulus field from only one halogen lamp guarantees wave-length-independent testing. Patients with various retinal diseases and neuritis nervi optici pathology were examined using pattern VEP, testing of the absolute lower threshold of light sensitivity, and binocular comparison over the range of luminous density. This binocular optical photometer system allowed minimal differences to be identified in the present visual function and after the eye had recovered from optic nerve neuritis. PMID:7780279

  6. The research on binocular stereo video imaging and display system based on low-light CMOS

    Science.gov (United States)

    Xie, Ruobing; Li, Li; Jin, Weiqi; Guo, Hong

    2015-10-01

    It is prevalent for the low-light night-vision helmet to equip the binocular viewer with image intensifiers. Such equipment can not only acquire night vision ability, but also obtain the sense of stereo vision to achieve better perception and understanding of the visual field. However, since the image intensifier is for direct-observation, it is difficult to apply the modern image processing technology. As a result, developing digital video technology in night vision is of great significance. In this paper, we design a low-light night-vision helmet with digital imaging device. It consists of three parts: a set of two low-illumination CMOS cameras, a binocular OLED micro display and an image processing PCB. Stereopsis is achieved through the binocular OLED micro display. We choose Speed-Up Robust Feature (SURF) algorithm for image registration. Based on the image matching information and the cameras' calibration parameters, disparity can be calculated in real-time. We then elaborately derive the constraints of binocular stereo display. The sense of stereo vision can be obtained by dynamically adjusting the content of the binocular OLED micro display. There is sufficient space for function extensions in our system. The performance of this low-light night-vision helmet can be further enhanced in combination with The HDR technology and image fusion technology, etc.

  7. Binocular Visual Navigation and Obstacle Avoidance of Mobile Robots Based on Speeded-Up Robust Features

    Institute of Scientific and Technical Information of China (English)

    WANG Meng-di; HAN Bao-ling; LUO Qing-sheng

    2013-01-01

    This article presents a good robust and real-time system scheme of the mobile robot obstacle detection and navigation, which principle of work is based on the feature descriptor SURF. In this scheme, firstly, the image information of the mobile robot path was captured by the binocular camera; then the feature points were extracted and corresponding matched using SURF to the binocular images as the undetected obstacles;finally fixed the position of the objective by the parallax between the matching points combining with the binocular vision calibration model. Theoretical derivation and experimental results show that this scheme is more accurate for the detection and navigation of the interest points. It has fast matching speed and high accuracy and low error. So, it has certain practical effect and popularizing value for the mobile robot real-time obstacle avoidance and navigation.

  8. Binocular fusion in Panum's limiting case of stereopsis obeys the uniqueness constraint

    Institute of Scientific and Technical Information of China (English)

    WANG; Zhihong; (王志宏); WU; Xinnian; (吴新年); NI; Rui; (倪睿); WANG; Yunjiu; (汪云九)

    2001-01-01

    In the information processing procedure of stereo vision, the uniqueness constraint has been used as one of the constraints to solve the "correspondence problem". While the uniqueness constraint is valid in most cases, whether it is still valid in some particular stimulus configuration (such as Panum's limiting case) has been a problem of widespread debate for a long time. To investigate the problem, we adopted the Panum's limiting case as its basic stimulus configuration, and delved into the phenomenon of binocular fusion from two distinct aspects: visual direction and orientation disparity. The results show that in Panum's limiting case binocular fusion does not comply with the rules governing regular binocular fusion as far as visual direction and orientation disparity are concerned. This indicates that double fusion does not happen in Panum's limiting case and that the uniqueness constraint is still valid.

  9. Binocular fusion in Panum's limiting case of stereopsisobeys the uniqueness constraint

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the information processing procedure of stereo vision, theuniqueness constraint has been used as one of the constraints to solve the "correspondence problem". While the uniqueness constraint is valid in most cases, whether it is still valid in some particular stimulus configuration (such as Panum's limiting case) has been a problem of widespread debate for a long time. To investigate the problem, we adopted the Panum's limiting case as its basic stimulus configuration, and delved into the phenomenon of binocular fusion from two distinct aspects: visual direction and orientation disparity. The results show that in Panum's limiting case binocular fusion does not comply with the rules governing regular binocular fusion as far as visual direction and orientation disparity are concerned. This indicates that double fusion does not happen in Panum's limiting case and that the uniqueness constraint is still valid.

  10. No-reference stereoscopic image quality measurement based on generalized local ternary patterns of binocular energy response

    Science.gov (United States)

    Zhou, Wujie; Yu, Lu

    2015-09-01

    Perceptual no-reference (NR) quality measurement of stereoscopic images has become a challenging issue in three-dimensional (3D) imaging fields. In this article, we propose an efficient binocular quality-aware features extraction scheme, namely generalized local ternary patterns (GLTP) of binocular energy response, for general-purpose NR stereoscopic image quality measurement (SIQM). More specifically, we first construct the binocular energy response of a distorted stereoscopic image with different stimuli of amplitude and phase shifts. Then, the binocular quality-aware features are generated from the GLTP of the binocular energy response. Finally, these features are mapped to the subjective quality score of the distorted stereoscopic image by using support vector regression. Experiments on two publicly available 3D databases confirm the effectiveness of the proposed metric compared with the state-of-the-art full reference and NR metrics.

  11. Effect of cover adjustment on binocular vision function in children with anisometropic amblyopia

    OpenAIRE

    Kai Zhu

    2016-01-01

    AIM:To explore and study the effect of cover adjustment on binocular visual function in children with anisometropic amblyopia.METHODS: Forty-five children with anisometropic amblyopia of our hospital from July 2014 to April 2015 were as the study group, and treated by cover adjustment. Then 40 cases of healthy volunteers were selected as the blank control group. The binocular visual function of the subjects was observed.RESULTS: Before treatments, at 1 and 3mo after treatments, the positive r...

  12. Development of monocular and binocular multi-focus 3D display systems using LEDs

    Science.gov (United States)

    Kim, Sung-Kyu; Kim, Dong-Wook; Son, Jung-Young; Kwon, Yong-Moo

    2008-04-01

    Multi-focus 3D display systems are developed and a possibility about satisfaction of eye accommodation is tested. The multi-focus means the ability of monocular depth cue to various depth levels. By achieving the multi-focus function, we developed 3D display systems for one eye and both eyes, which can satisfy accommodation to displayed virtual objects within defined depth. The monocular accommodation and the binocular convergence 3D effect of the system are tested and a proof of the satisfaction of the accommodation and experimental result of the binocular 3D fusion are given as results by using the proposed 3D display systems.

  13. Experimental platform for moving double-camera system based on binocular vergence eye movements

    Institute of Scientific and Technical Information of China (English)

    LI Heng-yu; LUO Jun; XIE Shao-rong; LI Lei; LI Qing-mei

    2009-01-01

    A control model of binocular vergence eye movements is presented. The control model can reduce blind areas caused by the double cameras in motion platform. In order to validate the model performance, an experimental platform and its control system based on TMS320LF2407 are designed. The control system has its compacted configuration and high reliability. The simulation and experimental results show that the control system can realize binocular vergence movements. Compared with the conventional moving double cameras system, this new system can considerably reduce blind areas.

  14. Altruism, Rivalry and Crowding-Out in the Nonprofit Firm's Supply of Charity Services: The Case of Hospitals

    OpenAIRE

    Frank, Richard G.; David S. Salkever

    1988-01-01

    This paper extends previous research on Individuals' supply of charitable donations to the behavior of nonprofit firms. Specifically, we study provision of charity care by private, nonprofit hospitals. We demonstrate that In the absence of large positive income effects on charity care supply, convex preferences for the nonprofit hospital imply crowding out by other private or government hospitals. Extending our model to include patient heterogeneity and impure altruism (rivalry) provides a po...

  15. Competition with and without priority control: linking rivalry to attention through winner-take-all networks with memory

    OpenAIRE

    Marx, Svenja; Gruenhage, Gina; Walper, Daniel; Rutishauser, Ueli; Einhäuser, Wolfgang

    2015-01-01

    Competition is ubiquitous in perception. For example, items in the visual field compete for processing resources, and attention controls their priority (biased competition). The inevitable ambiguity in the interpretation of sensory signals yields another form of competition: distinct perceptual interpretations compete for access to awareness. Rivalry, where two equally likely percepts compete for dominance, explicates the latter form of competition. Building upon the similarity between attent...

  16. Pengetahuan Dan Sikap Ibu Tentang Sibling Rivalry Di klinik Bersalin Hanafi Kel. Tanjung Gusta Kec. Medan-Helvetia Tahun 2012

    OpenAIRE

    Siregar, Dedi Kurnia

    2012-01-01

    Pengetahuan merupakan hasil dari tahu setelah orang melakukan suatu tindakan, sedangkan sikap merupakan suatu reaksi atau respons setelah orang melakukan suatu tindakan atau aktivitas. Sibling rivalry merupakan adanya rasa persaingan saudara kandung terhadap kelahiran adiknya untuk memperebutkan kasih sayang. berdasarkan wawancara yang telah dilakukan oleh peneliti kepada beberapa ibu – ibu di kelurahan Tanjung Gusta ternyata masih banyak ibu-ibu di daerah ini yang memperlakukan anak-anaknya...

  17. REGIONAL CENTERS OF POWER AND THEIR EURASIAN POLITICS ( RIVALRY IN THE ISLAMIC EAST—THE TURKISH VECTOR)

    OpenAIRE

    Varbanets, Pavel

    2008-01-01

    In the last twenty years, the international relations system has undergone major changes, however, contrary to America’s expectations, the bipolar world order that disappeared together with the Soviet Union and the end of the Cold War was not replaced with a unipolar world. Today, international processes are somewhat chaotic, which explains the appearance of several poles of power—the United States, EU, Russia, Southeast Asia, and the Islamic world. While in the West the rivalry over spheres ...

  18. A binocular pupil model for simulation of relative afferent pupil defect, RAPD.

    Science.gov (United States)

    Privitera, Claudio M; Stark, Lawrence W

    2004-01-01

    The human pupil is an important element studied in many clinical procedures. The binocular pupil model presented has a topology encompassing much of the complexity of the pupil system neurophysiology. The dynamic parameters of the model were matched against pupil experiments under multiple conditions. It simulates responses to the swinging flashlight test for different degrees of relative afferent pupil defects, RAPD. PMID:17271776

  19. Binocular self-calibration performed via adaptive genetic algorithm based on laser line imaging

    Science.gov (United States)

    Apolinar Muñoz Rodríguez, J.; Mejía Alanís, Francisco Carlos

    2016-07-01

    An accurate technique to perform binocular self-calibration by means of an adaptive genetic algorithm based on a laser line is presented. In this calibration, the genetic algorithm computes the vision parameters through simulated binary crossover (SBX). To carry it out, the genetic algorithm constructs an objective function from the binocular geometry of the laser line projection. Then, the SBX minimizes the objective function via chromosomes recombination. In this algorithm, the adaptive procedure determines the search space via line position to obtain the minimum convergence. Thus, the chromosomes of vision parameters provide the minimization. The approach of the proposed adaptive genetic algorithm is to calibrate and recalibrate the binocular setup without references and physical measurements. This procedure leads to improve the traditional genetic algorithms, which calibrate the vision parameters by means of references and an unknown search space. It is because the proposed adaptive algorithm avoids errors produced by the missing of references. Additionally, the three-dimensional vision is carried out based on the laser line position and vision parameters. The contribution of the proposed algorithm is corroborated by an evaluation of accuracy of binocular calibration, which is performed via traditional genetic algorithms.

  20. The Effects of Sports Vision Training on Binocular Vision Function in Female University Athletes

    Science.gov (United States)

    Zwierko, Teresa; Puchalska-Niedbał, Lidia; Krzepota, Justyna; Markiewicz, Mikołaj; Woźniak, Jarosław; Lubiński, Wojciech

    2015-01-01

    Binocular vision is the most important visual cue for spatial orientation in many sports. In this study, we investigated how binocular vision was influenced by an eye training program that may be used to improve individual's oculomotor function. The experiment involved twenty-four female student athletes from team ball sports (soccer, basketball, handball). After an initial testing session, 12 participants were randomly allocated to the experimental group. Optometric investigation which included synoptophore testing and a test of dissociated horizontal phoria based on the Maddox method was performed three times: before the experiment, after eight weeks of eye training (3 times a week for 20 minutes), and four weeks after the experiment was terminated. Eye exercise methodology was based on orthoptic, sport and psychological aspects of performance. The phoria screening examination showed that exophoria was the most frequent disorder of binocular vision. Low fusional vergence range was also observed. Following the training period, 3 of the 6 oculomotor variables improved. The greatest effect was observed in near dissociated phoria (χ2 =14.56, p=0.001 for the right eye; χ2 =14.757, p=0.001 for the left eye) and fusional convergence (χ2 =8.522, p=0.014). The results of the retention test conducted four weeks after the experiment confirmed the effectiveness of the vision training program. The results of the study suggest that binocular functions are trainable and can be improved by means of appropriate visual training. PMID:26925183

  1. Graphical and Normative Analysis of Binocular Vision by Mini Computer: A Teaching Aid and Clinical Tool.

    Science.gov (United States)

    Kees, Martin; Schor, Clifton

    1981-01-01

    An inexpensive computer graphics systems (Commodore PET), used as a video aid for teaching students advanced case analysis, is described. The course provides students with the analytical tools for evaluating with graphical and statistical techniques and treating with lenses, prisms, and orthoptics various anomalies of binocular vision. (MLW)

  2. The Effects of Sports Vision Training on Binocular Vision Function in Female University Athletes.

    Science.gov (United States)

    Zwierko, Teresa; Puchalska-Niedbał, Lidia; Krzepota, Justyna; Markiewicz, Mikołaj; Woźniak, Jarosław; Lubiński, Wojciech

    2015-12-22

    Binocular vision is the most important visual cue for spatial orientation in many sports. In this study, we investigated how binocular vision was influenced by an eye training program that may be used to improve individual's oculomotor function. The experiment involved twenty-four female student athletes from team ball sports (soccer, basketball, handball). After an initial testing session, 12 participants were randomly allocated to the experimental group. Optometric investigation which included synoptophore testing and a test of dissociated horizontal phoria based on the Maddox method was performed three times: before the experiment, after eight weeks of eye training (3 times a week for 20 minutes), and four weeks after the experiment was terminated. Eye exercise methodology was based on orthoptic, sport and psychological aspects of performance. The phoria screening examination showed that exophoria was the most frequent disorder of binocular vision. Low fusional vergence range was also observed. Following the training period, 3 of the 6 oculomotor variables improved. The greatest effect was observed in near dissociated phoria (χ(2) =14.56, p=0.001 for the right eye; χ(2) =14.757, p=0.001 for the left eye) and fusional convergence (χ(2) =8.522, p=0.014). The results of the retention test conducted four weeks after the experiment confirmed the effectiveness of the vision training program. The results of the study suggest that binocular functions are trainable and can be improved by means of appropriate visual training. PMID:26925183

  3. Project Report: Reducing Color Rivalry in Imagery for Conjugated Multiple Bandpass Filter Based Stereo Endoscopy

    Science.gov (United States)

    Ream, Allen

    2011-01-01

    A pair of conjugated multiple bandpass filters (CMBF) can be used to create spatially separated pupils in a traditional lens and imaging sensor system allowing for the passive capture of stereo video. This method is especially useful for surgical endoscopy where smaller cameras are needed to provide ample room for manipulating tools while also granting improved visualizations of scene depth. The significant issue in this process is that, due to the complimentary nature of the filters, the colors seen through each filter do not match each other, and also differ from colors as seen under a white illumination source. A color correction model was implemented that included optimized filter selection, such that the degree of necessary post-processing correction was minimized, and a chromatic adaptation transformation that attempted to fix the imaged colors tristimulus indices based on the principle of color constancy. Due to fabrication constraints, only dual bandpass filters were feasible. The theoretical average color error after correction between these filters was still above the fusion limit meaning that rivalry conditions are possible during viewing. This error can be minimized further by designing the filters for a subset of colors corresponding to specific working environments.

  4. Cataract surgery: emotional reactions of patients with monocular versus binocular vision Cirurgia de catarata: aspectos emocionais de pacientes com visão monocular versus binocular

    Directory of Open Access Journals (Sweden)

    Roberta Ferrari Marback

    2012-12-01

    Full Text Available PURPOSE: To analyze emotional reactions related to cataract surgery in two groups of patients (monocular vision - Group 1; binocular vision - Group 2. METHODS: A transversal comparative study was performed using a structured questionnaire from a previous exploratory study before cataract surgery. RESULTS: 206 patients were enrolled in the study, 96 individuals in Group 1 (69.3 ± 10.4 years and 110 in Group 2 (68.2 ± 10.2 years. Most patients in group 1 (40.6% and 22.7% of group 2, reported fear of surgery (pOBJETIVO: Verificar reações emocionais relacionadas à cirurgia de catarata entre pacientes com visão monocular (Grupo 1 e binocular (Grupo 2. MÉTODOS: Foi realizado um estudo tranversal, comparativo por meio de um questionário estruturado respondido por pacientes antes da cirurgia de catarata. RESULTADOS: A amostra foi composta de 96 pacientes no Grupo 1 (69.3 ± 10.4 anos e 110 no Grupo 2 (68.2 ± 10.2 anos. Consideravam apresentar medo da cirugia 40.6% do Grupo 1 e 22.7% do Grupo 2 (p<0.001 e entre as principais causas do medo, a possibilidade de perda da visão, complicações cirúrgicas e a morte durante o procedimento foram apontadas. Os sentimentos mais comuns entre os dois grupos foram dúvidas a cerca dos resultados da cirurgia e o nervosismo diante do procedimento. CONCLUSÃO: Pacientes com visão monocular apresentaram mais medo e dúvidas relacionadas à cirurgia de catarata comparados com aqueles com visão binocular. Portanto, é necessário que os médicos considerem estas reações emocionais e invistam mais tempo para esclarecer os riscos e benefícios da cirurgia de catarata.

  5. Binocular eyelid closure promotes anatomical but not behavioral recovery from monocular deprivation.

    Science.gov (United States)

    Duffy, Kevin R; Bukhamseen, Dalia H; Smithen, Matthew J; Mitchell, Donald E

    2015-09-01

    Deprivation of patterned vision of frontal eyed mammals early in postnatal life alters structural and functional attributes of neurones in the central visual pathways, and can produce severe impairments of the vision of the deprived eye that resemble the visual loss observed in human amblyopia. A traditional approach to treatment of amblyopia has been the occlusion of the stronger fellow eye in order to force use of the weaker eye and thereby strengthen its connections in the visual cortex. Although this monocular treatment strategy can be effective at promoting recovery of visual acuity of the amblyopic eye, such binocular visual functions as stereoscopic vision often remain impaired due in part to the lack of concordant vision during the period of unilateral occlusion. The recent development of binocular approaches for treatment of amblyopia that improve the possibility for binocular interaction have achieved success in promoting visual recovery. The full and rapid recovery of visual acuity observed in amblyopic kittens placed in complete darkness is an example of a binocular treatment whose success may in part derive from a restored balance of visually-driven neural activity. In the current study we examined as an alternative to dark rearing the efficacy of binocular lid suture (BLS) to stimulate anatomical and visual recovery from a preceding amblyogenic period of monocular deprivation. In the dorsal lateral geniculate nucleus (dLGN) of monocularly deprived kittens, darkness or BLS for 10days produced a complete recovery of neurone soma size within initially deprived layers. The growth of neurone somata within initially deprived dLGN layers after darkness or BLS was accompanied by an increase in neurotrophin-4/5 labeling within these layers. Although anatomical recovery was observed in both recovery conditions, BLS failed to promote any improvement of the visual acuity of the deprived eye no matter whether it followed immediately or was delayed with respect to

  6. Is there any evidence for the validity of diagnostic criteria used for accommodative and nonstrabismic binocular dysfunctions?

    OpenAIRE

    Cacho Martínez, Pilar; García Muñoz, Ángel; Ruiz Cantero, María Teresa

    2014-01-01

    Purpose: To analyze the diagnostic criteria used in the scientific literature published in the past 25 years for accommodative and nonstrabismic binocular dysfunctions and to explore if the epidemiological analysis of diagnostic validity has been used to propose which clinical criteria should be used for diagnostic purposes. Methods: We carried out a systematic review of papers on accommodative and non-strabic binocular disorders published from 1986 to 2012 analysing the MEDLINE, CINAHL, Psyc...

  7. Underwater binocular imaging of aerial objects versus the position of eyes relative to the flat water surface.

    Science.gov (United States)

    Barta, András; Horváth, Gábor

    2003-12-01

    The apparent position, size, and shape of aerial objects viewed binocularly from water change as a result of the refraction of light at the water surface. Earlier studies of the refraction-distorted structure of the aerial binocular visual field of underwater observers were restricted to either vertically or horizontally oriented eyes. Here we calculate the position of the binocular image point of an aerial object point viewed by two arbitrarily positioned underwater eyes when the water surface is flat. Assuming that binocular image fusion is performed by appropriate vergent eye movements to bring the object's image onto the foveae, the structure of the aerial binocular visual field is computed and visualized as a function of the relative positions of the eyes. We also analyze two erroneous representations of the underwater imaging of aerial objects that have occurred in the literature. It is demonstrated that the structure of the aerial binocular visual field of underwater observers distorted by refraction is more complex than has been thought previously. PMID:14686517

  8. Looking into the water with oblique head tilting: revision of the aerial binocular imaging of underwater objects.

    Science.gov (United States)

    Horváth, Gábor; Buchta, Krisztián; Varjú, Dezsö

    2003-06-01

    It is a well-known phenomenon that when we look into the water with two aerial eyes, both the apparent position and the apparent shape of underwater objects are different from the real ones because of refraction at the water surface. Earlier studies of the refraction-distorted structure of the underwater binocular visual field of aerial observers were restricted to either vertically or horizontally oriented eyes. We investigate a generalized version of this problem: We calculate the position of the binocular image point of an underwater object point viewed by two arbitrarily positioned aerial eyes, including oblique orientations of the eyes relative to the flat water surface. Assuming that binocular image fusion is performed by appropriate vergent eye movements to bring the object's image onto the foveas, the structure of the underwater binocular visual field is computed and visualized in different ways as a function of the relative positions of the eyes. We show that a revision of certain earlier treatments of the aerial imaging of underwater objects is necessary. We analyze and correct some widespread erroneous or incomplete representations of this classical geometric optical problem that occur in different textbooks. Improving the theory of aerial binocular imaging of underwater objects, we demonstrate that the structure of the underwater binocular visual field of aerial observers distorted by refraction is more complex than has been thought previously. PMID:12801180

  9. VLSI design of 3D display processing chip for binocular stereo displays

    Institute of Scientific and Technical Information of China (English)

    Ge Chenyang; Zheng Nanning

    2010-01-01

    In order to develop the core chip supporting binocular stereo displays for head mounted display(HMD)and glasses-TV,a very large scale integrated(VLSI)design scheme is proposed by using a pipeline architecture for 3D display processing chip(HMD100).Some key techniques including stereo display processing and high precision video scaling based bicubic interpolation,and their hardware implementations which improve the image quality are presented.The proposed HMD100 chip is verified by the field-programmable gate array(FPGA).As one of innovative and high integration SoC chips,HMD100 is designed by a digital and analog mixed circuit.It can support binocular stereo display,has better scaling effect and integration.Hence it is applicable in virtual reality(VR),3D games and other microdisplay domains.

  10. Evaluation of Binocular Eye Trackers and Algorithms for 3D Gaze Interaction in Virtual Reality Environments

    Directory of Open Access Journals (Sweden)

    Thies Pfeiffer

    2009-03-01

    Full Text Available Tracking user's visual attention is a fundamental aspect in novel human-computer interaction paradigms found in Virtual Reality. For example, multimodal interfaces or dialogue-based communications with virtual and real agents greatly benefit from the analysis of the user's visual attention as a vital source for deictic references or turn-taking signals. Current approaches to determine visual attention rely primarily on monocular eye trackers. Hence they are restricted to the interpretation of two-dimensional fixations relative to a defined area of projection.The study presented in this article compares precision, accuracy and application performance of two binocular eye tracking devices. Two algorithms are compared which derive depth information as required for visual attention-based 3D interfaces. This information is further applied to an improved VR selection task in which a binocular eye tracker and an adaptive neural network algorithm is used during the disambiguation of partly occluded objects.

  11. On the contribution of binocular disparity to the long-term memory for natural scenes.

    Directory of Open Access Journals (Sweden)

    Matteo Valsecchi

    Full Text Available Binocular disparity is a fundamental dimension defining the input we receive from the visual world, along with luminance and chromaticity. In a memory task involving images of natural scenes we investigate whether binocular disparity enhances long-term visual memory. We found that forest images studied in the presence of disparity for relatively long times (7s were remembered better as compared to 2D presentation. This enhancement was not evident for other categories of pictures, such as images containing cars and houses, which are mostly identified by the presence of distinctive artifacts rather than by their spatial layout. Evidence from a further experiment indicates that observers do not retain a trace of stereo presentation in long-term memory.

  12. Research on Extraction of Bottom of Shoe Pattern Based on Binocular Stereo Vision

    Institute of Scientific and Technical Information of China (English)

    MA Xin-wu; GAN Yi; SUN Fu-jia

    2016-01-01

    In order to quickly and efficiently get the information of the bottom of the shoe pattern and spraying trajectory, the paper proposes a method based on binocular stereo vision .After acquiring target image , edge detection based on the canny algorithm , the paper begins stereo matching based on area and characteristics of algorithm.To eliminate false matching points , the paper uses the principle of polar geometry in computer vision . For the purpose of gaining the 3D point cloud of spraying curve , the paper adopts the principle of binocular stereo vision 3D measurement , and then carries on cubic spline curve fitting .By HALCON image processing software programming , it proves the feasibility and effectiveness of the method .

  13. Camera calibration method of binocular stereo vision based on OpenCV

    Science.gov (United States)

    Zhong, Wanzhen; Dong, Xiaona

    2015-10-01

    Camera calibration, an important part of the binocular stereo vision research, is the essential foundation of 3D reconstruction of the spatial object. In this paper, the camera calibration method based on OpenCV (open source computer vision library) is submitted to make the process better as a result of obtaining higher precision and efficiency. First, the camera model in OpenCV and an algorithm of camera calibration are presented, especially considering the influence of camera lens radial distortion and decentering distortion. Then, camera calibration procedure is designed to compute those parameters of camera and calculate calibration errors. High-accurate profile extraction algorithm and a checkboard with 48 corners have also been used in this part. Finally, results of calibration program are presented, demonstrating the high efficiency and accuracy of the proposed approach. The results can reach the requirement of robot binocular stereo vision.

  14. Acceptance of different multifocal contact lenses depending on the binocular findings.

    Science.gov (United States)

    Cagnolati, W

    1993-04-01

    In a clinical study the subjective acceptance as well as the quality of different visual functions was examined during the wearing of three multifocal lenses (Ciba Spectrum Bifocal, Allergan Echelon, and Essilor Variations). Ten subjects wore each of the 3 contact lens types for a period of 12 to 21 days after the binocular finding (bicentral or disparate vision within the Panum's area); further functions such as contrast or scotopic vision were qualified and/or quantified in a basic examination. All subjects (N = 5) with the binocular finding orthophoria/motorcompensated heterophoria preferred the Ciba Spectrum Bifocal. Furthermore, all visual functions of the 10 test persons were clearly reduced with all 3 multifocal contact lenses. A correlation between the "preferred contact lens and the detailed subjective acceptance" and/or the "subjective acceptance and the functional measurements" could not be proven as statistically significant. PMID:8502460

  15. Operation of the adaptive optics system at the Large Binocular Telescope Observatory

    Science.gov (United States)

    Miller, Douglas L.; Guerra, Juan Carlos; Boutsia, Konstantina; Fini, Luca; Argomedo, Javier; Biddick, Chris; Agapito, Guido; Arcidiacono, Carmelo; Briguglio, Runa; Brusa, Guido; Busoni, Lorenzo; Esposito, Simone; Hill, John; Kulesa, Craig; McCarthy, Don; Pinna, Enrico; Puglisi, Alfio T.; Quiros-Pacheco, Fernando; Riccardi, Armando; Xompero, Marco

    2012-07-01

    The Adaptive Optics System at the Large Binocular Telescope Observatory consists of two Adaptive Secondary (ASM) mirrors and two Pyramid Wavefront sensors. The first ASM/Pyramid pair has been commissioned and is being used for science operation using the NIR camera PISCES on the right side of the binocular telescope. The left side ASM/Pyramid system is currently being commissioned, with completion scheduled for the Fall of 2012. We will discuss the operation of the first Adaptive Optics System at the LBT Observatory including interactions of the AO system with the telescope and its TCS, observational modes, user interfaces, observational scripting language, time requirement for closed loop and offsets and observing efficiency.

  16. Egg size and asymmetric sibling rivalry in red-winged blackbirds.

    Science.gov (United States)

    Forbes, Scott; Wiebe, Mark

    2010-06-01

    How big to make an egg is a life history decision that in birds is made coincident with a series of other similar decisions (how many eggs to have, whether to fortify them with maternally derived hormones or immune system boosters, whether to hatch the eggs synchronously or asynchronously). Though within-population variation in egg size in birds has been well studied, its adaptive significance, if any, is unclear. Here we examine within-population variation in egg size in relation to asymmetric sibling rivalry in a 17-year study of red-winged blackbirds (Agelaius phoeniceus), an altricial songbird. Egg mass showed a twofold range of variation, with roughly 80% of the variation occurring across clutches. By commencing incubation before the clutch is complete, mothers create advantaged core and disadvantaged marginal elements within their brood. Previous work on this system has shown that sibling competition is asymmetric, and that core offspring enjoy priority access to food, and as a consequence show higher growth and lower mortality than marginal offspring. Here we examine the effect of initial egg size on nestling growth and survival in relation to these competitive asymmetries. Egg mass was strongly linked to hatchling mass, and remained significantly related to the mass of both core and marginal nestlings; the effect of egg size was stronger for core offspring early in the nestling period, but the disparity between core and marginal nestlings narrowed as they approached fledging age, and slower growing marginals fell victim to brood reduction. The effect of egg mass on survival differed dramatically between core and marginal nestlings. Egg mass was significantly related to the survival of marginal but not core nestlings: below average egg mass was associated primarily with very early mortality. Asymmetric sibling competition is clearly a strong determinant of the consequences of egg size variation. PMID:20401493

  17. Rivalry of homeostatic and sensory-evoked emotions: Dehydration attenuates olfactory disgust and its neural correlates.

    Science.gov (United States)

    Meier, Lea; Friedrich, Hergen; Federspiel, Andrea; Jann, Kay; Morishima, Yosuke; Landis, Basile Nicolas; Wiest, Roland; Strik, Werner; Dierks, Thomas

    2015-07-01

    Neural correlates have been described for emotions evoked by states of homeostatic imbalance (e.g. thirst, hunger, and breathlessness) and for emotions induced by external sensory stimulation (such as fear and disgust). However, the neurobiological mechanisms of their interaction, when they are experienced simultaneously, are still unknown. We investigated the interaction on the neurobiological and the perceptional level using subjective ratings, serum parameters, and functional magnetic resonance imaging (fMRI) in a situation of emotional rivalry, when both a homeostatic and a sensory-evoked emotion were experienced at the same time. Twenty highly dehydrated male subjects rated a disgusting odor as significantly less repulsive when they were thirsty. On the neurobiological level, we found that this reduction in subjective disgust during thirst was accompanied by a significantly reduced neural activity in the insular cortex, a brain area known to be considerably involved in processing of disgust. Furthermore, during the experience of disgust in the satiated condition, we observed a significant functional connectivity between brain areas responding to the disgusting odor, which was absent during the stimulation in the thirsty condition. These results suggest interference of conflicting emotions: an acute homeostatic imbalance can attenuate the experience of another emotion evoked by the sensory perception of a potentially harmful external agent. This finding offers novel insights with regard to the behavioral relevance of biologically different types of emotions, indicating that some types of emotions are more imperative for behavior than others. As a general principle, this modulatory effect during the conflict of homeostatic and sensory-evoked emotions may function to safeguard survival. PMID:25818686

  18. Devil aka Satan: An enemy or fiend? On the rivalry between the familiar and the foreign in early English

    OpenAIRE

    Esquibel, Joanna; Wojtyś, Anna

    2012-01-01

    The present paper discusses the distribution of the two most common Mediaeval English euphemisms of Satan, i.e. fiend and enemy, in religious prose. We focus on the rivalry between the foreign word and the native word, comparing the contexts in which the two words tended to occur, and attempting to determine the semantic status of the French word enemy in relation to the sense originally denoted by fiend. The data come from the Middle English period, when French loanwords began to compete sem...

  19. The Search for Failed Supernovae with The Large Binocular Telescope: First Candidates

    CERN Document Server

    Gerke, J R; Stanek, K Z

    2014-01-01

    We are monitoring 27 galaxies within 10 Mpc using the Large Binocular Telescope to search for failed supernovae (SNe), massive stars that collapse to form a black hole without a SN explosion. This sample yielded 3 successful SNe during the 4 year survey period. We search for stars that have "vanished" over the course of our survey, by examining all stars showing a decrease in luminosity of $\\Delta \

  20. Camera Calibration Method of Medical Robot Positioning System Based on Binocular Vision

    OpenAIRE

    Dong Feng; Sun Li-Ning; Ru Chang-Hai

    2013-01-01

    The medical robot positioning system plays an important role in the precise radiotherapy, so the study proposes the measure system based binocular vision to reduce the patient=s setup errors for the initial positioning rapidly and accurately. In order to get higher positioning accuracy, the study proposes a new non-contact camera calibration method based on planar and 3D checkerboard calibration templates. The experimental results show that camera calibrati...

  1. Do we really know the prevalence of accomodative and nonstrabismic binocular dysfunctions?

    OpenAIRE

    Cacho Martínez, Pilar; García Muñoz, Ángel; Ruiz Cantero, María Teresa

    2011-01-01

    Purpose: To determine the scientific evidence about the prevalence of accommodative and nonstrabismic binocular anomalies. Methods: We carried out a systematic review of studies published between 1986 and 2009, analysing the MEDLINE, CINAHL, FRANCIS and PsycINFO databases. We considered admitting those papers related to prevalence in paediatric and adult populations. We identified 660 articles and 10 papers met the inclusion criteria. Results: There is a wide range of prevalence, particularly...

  2. Prevalence of Accommodative and Non-Strabismic Binocular Anomalies in a Puerto Rican Pediatric Population

    OpenAIRE

    Stefania M. Paniccia, OD, MS; Angel Romero Ayala, OD

    2015-01-01

    Background: There exists a considerable void in the literature of studies that examine the prevalence of non-strabismic binocular and accommodative disorders in the pediatric population of Puerto Rico. The purpose of this retrospective study was to fill this void by performing a comprehensive record review of the pediatric clinical population of the InterAmerican University College of Optometry satellite clinics. Methods: This study was performed using a random selection of 593 existing h...

  3. The wavelet transform and the suppression theory of binocular vision for stereo image compression

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, W.D. Jr [Argonne National Lab., IL (United States); Kenyon, R.V. [Illinois Univ., Chicago, IL (United States)

    1996-08-01

    In this paper a method for compression of stereo images. The proposed scheme is a frequency domain approach based on the suppression theory of binocular vision. By using the information in the frequency domain, complex disparity estimation techniques can be avoided. The wavelet transform is used to obtain a multiresolution analysis of the stereo pair by which the subbands convey the necessary frequency domain information.

  4. Synchronizing retinal activity in both eyes disrupts binocular map development in the optic tectum

    OpenAIRE

    Brickley, S.; Dawes, E.; Keating, M; Grant, S

    1998-01-01

    Spatiotemporal correlations in the pattern of spontaneous and evoked retinal ganglion cell (RGC) activity are believed to influence the topographic organization of connections throughout the developing visual system. We have tested this hypothesis by examining the effects of interfering with these potential activity cues during development on the functional organization of binocular maps in the Xenopus frog optic tectum. Paired recordings combined with cross-correlation analyses demonstrated ...

  5. Voluntary binocular gaze-shifts in the plane of regard: Dynamics of version and vergence

    OpenAIRE

    Collewijn, Han; Erkelens, Dirk Willem; Steinman, Robert

    1995-01-01

    textabstractWe studied the dynamics of voluntary, horizontal, binocular gaze-shifts between pairs of continuously visible, real three-dimensional targets. Subjects were stabilized on a biteboard to allow full control of target angles, which were made to differ only in distance (pure vergence), only in direction (pure version; conjugate saccades) or in both distance and direction (disjunctive saccades). A wide range of changes in vergence (0-25 deg) and version (0-65 deg) was recorded to study...

  6. Disparity vergence responses before versus after repetitive vergence therapy in binocularly normal controls.

    Science.gov (United States)

    Talasan, Henry; Scheiman, Mitchell; Li, Xiaobo; Alvarez, Tara L

    2016-01-01

    This study sought to determine whether significant changes would be observed between vergence eye movements before and after 12 hr of repetitive vergence therapy (1 hr per day on different days) in subjects with normal binocular vision compared to controls. Disparity vergence responses from 23 subjects were studied. An assessment protocol that minimized the influence of the near dissociated phoria on the disparity vergence system was designed. The following parameters were quantified for the responses: latency, time to peak velocity, settling time, peak velocity, and accuracy (difference between the response and stimulus amplitudes). The following outcomes were observed when comparing the results after vergence therapy to the baseline measurements: (a) near point of convergence and near dissociated phoria did not significantly change (p > 0.15); (b) latency, time to peak velocity, and settling time significantly decreased (p ≤ 0.01); and (c) accuracy significantly improved (p eye movement responses from subjects with normal binocular vision can be improved after vergence therapy. These methods can be utilized within future studies to quantitatively assess vergence therapy techniques for patients with binocular dysfunction. PMID:26762276

  7. Ecomorphology of orbit orientation and the adaptive significance of binocular vision in primates and other mammals.

    Science.gov (United States)

    Heesy, Christopher P

    2008-01-01

    Primates are characterized by forward-facing, or convergent, orbits and associated binocular field overlap. Hypotheses explaining the adaptive significance of these traits often relate to ecological factors, such as arboreality, nocturnal visual predation, or saltatory locomotion in a complex nocturnal, arboreal environment. This study re-examines the ecological factors that are associated with high orbit convergence in mammals. Orbit orientation data were collected for 321 extant taxa from sixteen orders of metatherian (marsupial) and eutherian mammals. These taxa were coded for activity pattern, degree of faunivory, and substrate preference. Results demonstrate that nocturnal and cathemeral mammals have significantly more convergent orbits than diurnal taxa, both within and across orders. Faunivorous eutherians (both nocturnal and diurnal) have higher mean orbit convergence than opportunistically foraging or non-faunivorous taxa. However, substrate preference is not associated with higher orbit convergence and, by extension, greater binocular visual field overlap. These results are consistent with the hypothesis that mammalian predators evolved higher orbit convergence, binocular vision, and stereopsis to counter camouflage in prey inhabiting a nocturnal environment. Strepsirhine primates have a range of orbit convergence values similar to nocturnal or cathemeral predatory non-primate mammals. These data are entirely consistent with the nocturnal visual predation hypothesis of primate origins. PMID:17878718

  8. Comparison of binocular through-focus visual acuity with monovision and a small aperture inlay.

    Science.gov (United States)

    Schwarz, Christina; Manzanera, Silvestre; Prieto, Pedro M; Fernández, Enrique J; Artal, Pablo

    2014-10-01

    Corneal small aperture inlays provide extended depth of focus as a solution to presbyopia. As this procedure is becoming more popular, it is interesting to compare its performance with traditional approaches, such as monovision. Here, binocular visual acuity was measured as a function of object vergence in three subjects by using a binocular adaptive optics vision analyzer. Visual acuity was measured at two luminance levels (photopic and mesopic) under several optical conditions: 1) natural vision (4 mm pupils, best corrected distance vision), 2) pure-defocus monovision ( + 1.25 D add in the nondominant eye), 3) small aperture monovision (1.6 mm pupil in the nondominant eye), and 4) combined small aperture and defocus monovision (1.6 mm pupil and a + 0.75 D add in the nondominant eye). Visual simulations of a small aperture corneal inlay suggest that the device extends DOF as effectively as traditional monovision in photopic light, in both cases at the cost of binocular summation. However, individual factors, such as aperture centration or sensitivity to mesopic conditions should be considered to assure adequate visual outcomes. PMID:25360355

  9. Loss of binocular vision as direct cause for misrouting of temporal retinal fibers in albinism.

    Science.gov (United States)

    Banihani, Saleh M

    2015-10-01

    In humans, the nasal retina projects to the contralateral hemisphere, whereas the temporal retina projects ipsilaterally. The nasotemporal line that divides the retina into crossed and uncrossed parts coincides with the vertical meridian through the fovea. This normal projection of the retina is severely altered in albinism, in which the nasotemporal line shifted into the temporal retina with temporal retinal fibers cross the midline at the optic chiasm. This study proposes the loss of binocular vision as direct cause for misrouting of temporal retinal fibers and shifting of the nasotemporal line temporally in albinism. It is supported by many observations that clearly indicate that loss of binocular vision causes uncrossed retinal fibers to cross the midline. This hypothesis may alert scientists and clinicians to find ways to prevent or minimize the loss of binocular vision that may occur in some diseases such as albinism and early squint. Hopefully, this will minimize the misrouting of temporal fibers and improve vision in such diseases. PMID:26163060

  10. Corneal Transplantation in Disease Affecting Only One Eye: Does It Make a Difference to Habitual Binocular Viewing?

    Directory of Open Access Journals (Sweden)

    Praveen K Bandela

    Full Text Available Clarity of the transplanted tissue and restoration of visual acuity are the two primary metrics for evaluating the success of corneal transplantation. Participation of the transplanted eye in habitual binocular viewing is seldom evaluated post-operatively. In unilateral corneal disease, the transplanted eye may remain functionally inactive during binocular viewing due to its suboptimal visual acuity and poor image quality, vis-à-vis the healthy fellow eye.This study prospectively quantified the contribution of the transplanted eye towards habitual binocular viewing in 25 cases with unilateral transplants [40yrs (IQR: 32-42yrs and 25 age-matched controls [30yrs (25-37yrs]. Binocular functions including visual field extent, high-contrast logMAR acuity, suppression threshold and stereoacuity were assessed using standard psychophysical paradigms. Optical quality of all eyes was determined from wavefront aberrometry measurements. Binocular visual field expanded by a median 21% (IQR: 18-29% compared to the monocular field of cases and controls (p = 0.63. Binocular logMAR acuity [0.0 (0.0-0.0] almost always followed the fellow eye's acuity [0.00 (0.00 --0.02] (r = 0.82, independent of the transplanted eye's acuity [0.34 (0.2-0.5] (r = 0.04. Suppression threshold and stereoacuity were poorer in cases [30.1% (13.5-44.3%; 620.8arc sec (370.3-988.2arc sec] than in controls [79% (63.5-100%; 16.3arc sec (10.6-25.5arc sec] (p<0.001. Higher-order wavefront aberrations of the transplanted eye [0.34μ (0.21-0.51μ] were higher than the fellow eye [0.07μ (0.05-0.11μ] (p<0.001 and their reduction with RGP contact lenses [0.09μ (0.08-0.12μ] significantly improved the suppression threshold [65% (50-72%] and stereoacuity [56.6arc sec (47.7-181.6arc sec] (p<0.001.In unilateral corneal disease, the transplanted eye does participate in gross binocular viewing but offers limited support to fine levels of binocularity. Improvement in the transplanted eye's optics

  11. Corneal Transplantation in Disease Affecting Only One Eye: Does It Make a Difference to Habitual Binocular Viewing?

    Science.gov (United States)

    Bandela, Praveen K.; Satgunam, PremNandhini; Garg, Prashant; Bharadwaj, Shrikant R.

    2016-01-01

    Background Clarity of the transplanted tissue and restoration of visual acuity are the two primary metrics for evaluating the success of corneal transplantation. Participation of the transplanted eye in habitual binocular viewing is seldom evaluated post-operatively. In unilateral corneal disease, the transplanted eye may remain functionally inactive during binocular viewing due to its suboptimal visual acuity and poor image quality, vis-à-vis the healthy fellow eye. Methods and Findings This study prospectively quantified the contribution of the transplanted eye towards habitual binocular viewing in 25 cases with unilateral transplants [40yrs (IQR: 32–42yrs) and 25 age-matched controls [30yrs (25–37yrs)]. Binocular functions including visual field extent, high-contrast logMAR acuity, suppression threshold and stereoacuity were assessed using standard psychophysical paradigms. Optical quality of all eyes was determined from wavefront aberrometry measurements. Binocular visual field expanded by a median 21% (IQR: 18–29%) compared to the monocular field of cases and controls (p = 0.63). Binocular logMAR acuity [0.0 (0.0–0.0)] almost always followed the fellow eye’s acuity [0.00 (0.00 –-0.02)] (r = 0.82), independent of the transplanted eye’s acuity [0.34 (0.2–0.5)] (r = 0.04). Suppression threshold and stereoacuity were poorer in cases [30.1% (13.5–44.3%); 620.8arc sec (370.3–988.2arc sec)] than in controls [79% (63.5–100%); 16.3arc sec (10.6–25.5arc sec)] (p<0.001). Higher-order wavefront aberrations of the transplanted eye [0.34μ (0.21–0.51μ)] were higher than the fellow eye [0.07μ (0.05–0.11μ)] (p<0.001) and their reduction with RGP contact lenses [0.09μ (0.08–0.12μ)] significantly improved the suppression threshold [65% (50–72%)] and stereoacuity [56.6arc sec (47.7–181.6arc sec)] (p<0.001). Conclusions In unilateral corneal disease, the transplanted eye does participate in gross binocular viewing but offers limited support

  12. Binocular summation and other forms of non-dominant eye contribution in individuals with strabismic amblyopia during habitual viewing.

    Directory of Open Access Journals (Sweden)

    Brendan T Barrett

    Full Text Available BACKGROUND: Adults with amblyopia ('lazy eye', long-standing strabismus (ocular misalignment or both typically do not experience visual symptoms because the signal from weaker eye is given less weight than the signal from its fellow. Here we examine the contribution of the weaker eye of individuals with strabismus and amblyopia with both eyes open and with the deviating eye in its anomalous motor position. METHODOLOGY/RESULTS: The task consisted of a blue-on-yellow detection task along a horizontal line across the central 50 degrees of the visual field. We compare the results obtained in ten individuals with strabismic amblyopia with ten visual normals. At each field location in each participant, we examined how the sensitivity exhibited under binocular conditions compared with sensitivity from four predictions, (i a model of binocular summation, (ii the average of the monocular sensitivities, (iii dominant-eye sensitivity or (iv non-dominant-eye sensitivity. The proportion of field locations for which the binocular summation model provided the best description of binocular sensitivity was similar in normals (50.6% and amblyopes (48.2%. Average monocular sensitivity matched binocular sensitivity in 14.1% of amblyopes' field locations compared to 8.8% of normals'. Dominant-eye sensitivity explained sensitivity at 27.1% of field locations in amblyopes but 21.2% in normals. Non-dominant-eye sensitivity explained sensitivity at 10.6% of field locations in amblyopes but 19.4% in normals. Binocular summation provided the best description of the sensitivity profile in 6/10 amblyopes compared to 7/10 of normals. In three amblyopes, dominant-eye sensitivity most closely reflected binocular sensitivity (compared to two normals and in the remaining amblyope, binocular sensitivity approximated to an average of the monocular sensitivities. CONCLUSIONS: Our results suggest a strong positive contribution in habitual viewing from the non-dominant eye in

  13. Effect of Near Work on Binocular Vision Measurements in Adults with Convergence Insufficiency

    Directory of Open Access Journals (Sweden)

    Yi Pang, OD, PhD

    2015-02-01

    Full Text Available Background: Convergence insufficiency (CI is a common binocular vision disorder. A common characteristic of CI is that patients have more symptoms, such as eyestrain and headache, after close work. The purpose of this study was to determine whether 30 minutes of reading affects the binocular and accommodative measurements used in the diagnosis of CI. Methods: Eighteen normal adult subjects and eighteen adult CI subjects (symptomatic and asymptomatic were recruited. None of the CI subjects had accommodative insufficiency. The following measurements were made: distance and near cover test, near point of convergence (NPC with accommodative target (AT, NPC with transilluminator and red lens (RL, near positive fusional vergence (PFV, and accommodative amplitude. Subjects were then asked to read a book for 30 minutes, immediately followed by repeated administration of the above tests by the same examiner. Statistical analysis was performed using a Student’s paired t-test to compare the measurements before and after reading. Results: In the CI group, the mean phoria at near changed from 7.06Δ exophoria to 6.56Δ exophoria after reading for 30 minutes. Mean NPC break with AT changed from 9.58 cm to 11.25 cm. With RL, an average increase from 12.56 cm to 13.93 cm occurred for NPC break. Mean PFV break decreased from 17.22Δ to 15.56Δ . Mean amplitude of accommodation (OD changed from 7.46 to 7.56 diopters. Only the change in NPC break with AT after reading was statistically significant (P = 0.007. There were minimal changes in clinical measurements after reading in the normal subjects. Conclusion: Half an hour of reading had a statistically significant effect on the NPC break with AT but not on other binocular vision measurements in subjects with CI. It is unknown whether a longer period of reading would have a greater effect.

  14. A Standardized Procedure and Normative Values for Measuring Binocular Dynamic Visual Acuity

    Directory of Open Access Journals (Sweden)

    Amanda Miskewicz-Zastrow, OD

    2015-04-01

    Full Text Available Background: Binocular dynamic visual acuity (BDVA is the ability to differentiate fine details in a moving object such as seams on a pitched baseball or the rotation of a tennis ball, both of which can travel up to speeds exceeding 100 miles per hour. BDVA is one of many binocular visual measurements to examine binocular function. This study was designed to provide a standardized procedure for measuring BDVA and normal values for a sample population. Previous studies have used different techniques for measurement, and thus have no normative data for comparison. Methods: The BCVA attachment to the Bernell Rotation Trainer was used to measure BDVA in 22 subjects (10 females and 12 males between the ages of 23 and 30. Only subjects with a refractive error between +1.00 D and -7.00 D (spherical equivalent and with best corrected visual acuity of 20/20 or better were able to participate in the study. BDVA was recorded at three different rotation speeds (29 RPM, 24 RPM, and 16 RPM. At each RPM, accuracy and the time to completion of all nine lines were measured. The subjects were also asked to complete a questionnaire designed to evaluate factors that may influence the BDVA results. Results: A decrease in RPM resulted in a corresponding decrease in the subject’s completion time and an increase in accuracy. The same trend was seen when comparing males and females; however, the females’ accuracy was lower and the time was greater when compared to the males, but these were not statistically significant. Conclusions: This was the first study designed to use the Bernell Rotation Trainer to quantitatively measure BDVA in a standardized way. Our results showed similar trends in both males and females. In addition, this study provides a strong foundation for future research, such as comparing BDVA of athletes and non-athletes, or comparing athletes with different skill levels, or comparing athletes who participate in different sports.

  15. Neuronal convergence in early contrast vision: Binocular summation is followed by response nonlinearity and area summation

    OpenAIRE

    Meese, Tim S.; Summers, Robert J.

    2009-01-01

    We assessed summation of contrast across eyes and area at detection threshold (Ct). Stimuli were sine-wave gratings (2.5 c/deg) spatially modulated by cosine- and anticosine-phase raised plaids (0.5 c/deg components oriented at ±45°). When presented dichoptically the signal regions were interdigitated across eyes but produced a smooth continuous grating following their linear binocular sum. The average summation ratio (Ct1/([Ct1+2]) for this stimulus pair was 1.64 (4.3 dB). This was only slig...

  16. Secondary imprinting in the domestic chick: Binocular and lateralized monocular performance

    OpenAIRE

    Vallortigara, Giorgio; Regolin, Lucia; Zucca, Paolo

    2000-01-01

    Newly-hatched chicks were reared with a coloured imprinting object on day 1 of life (primary imprinting) and then with an object of a different colour (secondary imprinting) on day 2. They were then tested on day 3 for preferences between the primary and the secondary imprinting object in binocular and in monocular conditions. The main results were that (1) left-eyed chicks usually showed clearer choice than right-eyed chicks; (2) there were colour preferences that appeared to affect choice d...

  17. Monocular and binocular steady-state flicker VEPs: frequency-response functions to sinusoidal and square-wave luminance modulation.

    Science.gov (United States)

    Nicol, David S; Hamilton, Ruth; Shahani, Uma; McCulloch, Daphne L

    2011-02-01

    Steady-state VEPs to full-field flicker (FFF) using sinusoidally modulated light were compared with those elicited by square-wave modulated light across a wide range of stimulus frequencies with monocular and binocular FFF stimulation. Binocular and monocular VEPs were elicited in 12 adult volunteers to FFF with two modes of temporal modulation: sinusoidal or square-wave (abrupt onset and offset, 50% duty cycle) at ten temporal frequencies ranging from 2.83 to 58.8 Hz. All stimuli had a mean luminance of 100 cd/m(2) with an 80% modulation depth (20-180 cd/m(2)). Response magnitudes at the stimulus frequency (F1) and at the double and triple harmonics (F2 and F3) were compared. For both sinusoidal and square-wave flicker, the FFF-VEP magnitudes at F1 were maximal for 7.52 Hz flicker. F2 was maximal for 5.29 Hz flicker, and F3 magnitudes are largest for flicker stimulation from 3.75 to 7.52 Hz. Square-wave flicker produced significantly larger F1 and F2 magnitudes for slow flicker rates (up to 5.29 Hz for F1; at 2.83 and 3.75 Hz for F2). The F3 magnitudes were larger overall for square-wave flicker. Binocular FFF-VEP magnitudes are larger than those of monocular FFF-VEPs, and the amount of this binocular enhancement is not dependant on the mode of flicker stimulation (mean binocular: monocular ratio 1.41, 95% CI: 1.2-1.6). Binocular enhancement of F1 for 21.3 Hz flicker was increased to a factor of 2.5 (95% CI: 1.8-3.5). In the healthy adult visual system, FFF-VEP magnitudes can be characterized by the frequency-response functions of F1, F2 and F3. Low-frequency roll-off in the FFF-VEP magnitudes is greater for sinusoidal flicker than for square-wave flicker for rates ≤ 5.29 Hz; magnitudes for higher-frequency flicker are similar for the two types of flicker. Binocular FFF-VEPs are larger overall than those recorded monocularly, and this binocular summation is enhanced at 21.3 Hz in the mid-frequency range. PMID:21279419

  18. Evaluation of a four month rehabilitation program for stroke patients with balance problems and binocular visual dysfunction

    DEFF Research Database (Denmark)

    Schow, Trine; Harris, Paul; Teasdale, Thomas William;

    2016-01-01

    Trine Schow, Paul Harris, Thomas William Teasdale, Morten Arendt Rasmussen. Evaluation of a four month rehabilitation program for stroke patients with balance problems and binocular visual dysfunction. NeuroRehabilitation. 2016 Apr 6;38(4):331-41. doi: 10.3233/NRE-161324.......Trine Schow, Paul Harris, Thomas William Teasdale, Morten Arendt Rasmussen. Evaluation of a four month rehabilitation program for stroke patients with balance problems and binocular visual dysfunction. NeuroRehabilitation. 2016 Apr 6;38(4):331-41. doi: 10.3233/NRE-161324....

  19. Measurement error analysis of three dimensional coordinates of tomatoes acquired using the binocular stereo vision

    Science.gov (United States)

    Xiang, Rong

    2014-09-01

    This study analyzes the measurement errors of three dimensional coordinates of binocular stereo vision for tomatoes based on three stereo matching methods, centroid-based matching, area-based matching, and combination matching to improve the localization accuracy of the binocular stereo vision system of tomato harvesting robots. Centroid-based matching was realized through the matching of the feature points of centroids of tomato regions. Area-based matching was realized based on the gray similarity between two neighborhoods of two pixels to be matched in stereo images. Combination matching was realized using the rough disparity acquired through centroid-based matching as the center of the dynamic disparity range which was used in area-based matching. After stereo matching, three dimensional coordinates of tomatoes were acquired using the triangle range finding principle. Test results based on 225 stereo images captured at the distances from 300 to 1000 mm of 3 tomatoes showed that the measurement errors of x coordinates were small, and can meet the need of harvesting robots. However, the measurement biases of y coordinates and depth values were large, and the measurement variation of depth values was also large. Therefore, the measurement biases of y coordinates and depth values, and the measurement variation of depth values should be corrected in the future researches.

  20. Current Status of the Facility Instrumentation Suite at The Large Binocular Telescope Observatory

    CERN Document Server

    Rothberg, Barry; Edwards, Michelle L; Hill, John M; Thompson, David; Veillet, Christian; Wagner, R Mark

    2016-01-01

    We review the current status of the facility instrumentation for the Large Binocular Telescope (LBT). The LBT has 2x 8.4m primary mirrors on a single mount with an effective collecting area of 11.8m or 23m when interferometrically combined. The facility instruments are: 1) the Large Binocular Cameras (LBCs), each with a 23'x25' field of view (FOV). The blue and red optimized optical LBCs are mounted at the prime focus of the left and right primary mirrors, respectively. The filter suite of the two LBCs covers 0.3-1.1{\\mu}m, including the new TiO (0.78{\\mu}m) and CN (0.82{\\mu}m) filters; 2) the Multi-Object Double Spectrograph (MODS), two identical optical spectrographs each mounted at a straight through f/15 Gregorian mount. MODS-1 & -2 can do imaging with Sloan filters and medium resolution (R~2000) spectroscopy, each with 24 interchangeable masks (multi-object or longslit) over a 6'x6' FOV. Each MODS is capable of blue (0.32-0.6{\\mu}m) and red (0.5-1.05{\\mu}m) wavelength only coverage or, using a dichro...

  1. Enhancement display of veins distribution based on binocular vision and image fusion technology

    Science.gov (United States)

    Liu, Peng; Di, Si; Jin, Jian; Bai, Liping

    2014-11-01

    The capture and display of veins distribution is an important issue for some applications, such as medical diagnosis and identification. Therefore, it has become a popular topic in the field of biomedical imaging. Usually, people capture the veins distribution by infrared imaging, but the display result is similar with that of a gray picture and the color and details of skin cannot be remained. To some degree, it is unreal for doctors. In this paper, we develop a binocular vision system to carry out the enhancement display of veins under the condition of keeping actual skin color. The binocular system is consisted of two adjacent cameras. A visible band filter and an infrared band filter are placed in front of the two lenses, respectively. Therefore, the pictures of visible band and infrared band can be captured simultaneously. After that, a new fusion process is applied to the two pictures, which related to histogram mapping, principal component analysis (PCA) and modified bilateral filter fusion. The final results show that both the veins distribution and the actual skin color of the back of the hand can be clearly displayed. Besides, correlation coefficient, average gradient and average distortion are selected as the parameters to evaluate the image quality. By comparing the parameters, it is evident that our novel fusion method is prior to some popular fusion methods such as Gauss filter fusion, Intensity-hue-saturation (HIS) fusion and bilateral filter fusion.

  2. The relationship between binocular vision symptoms and near point of convergence

    Directory of Open Access Journals (Sweden)

    Momeni-Moghaddam Hamed

    2013-01-01

    Full Text Available Aim and Background: Due to the relatively high prevalence of binocular vision anomalies, a regular examination including tests for assessment and determination of these anomalies is necessary. The aim of this study was to assess the relationship between near point of convergence (NPC and near binocular vision symptoms and finding of an NPC cutoff point for symptoms in university students. Materials and Methods: In this cross-sectional study, 124 students of different majors of Zahedan University of Medical Sciences were randomly selected. If they met the inclusion criteria, they were divided into two groups (symptomatic and asymptomatic according to the convergence insufficiency symptom survey questionnaire. For NPC measurement, a small isolated letter "E" of approximately 20/30 size on a metal rod was used. After data collection, data were analyzed in SPSS.17 software (SPSS for Windows, SPSS Inc., Chicago, IL using descriptive and analytical statistics, including Mann-Whitney U test and receiver operating characteristic (ROC curve. Results: The mean NPC findings in the symptomatic and asymptomatic groups were 11.7 ± 5.0 and 8.4 ± 3.4 cm, respectively, with a significant difference between the two groups (P < 0.001. The ROC curve suggests an NPC cutoff point of 9.5 cm for the presence of symptoms with the testing procedures used in this study. Conclusion : The determination of NPC is helpful in the differentiation of symptomatic from asymptomatic subjects.

  3. On-sky single-mode fiber coupling measurements at the Large Binocular Telescope

    CERN Document Server

    Bechter, Andrew; Ketterer, Ryan; Crepp, Justin R; Reynolds, Robert O; Bechter, Eric; Hinz, Philip; Pedichini, Fernando; Foley, Michael; Runburg, Elliott; Onuma, Eleanya; Gaudi, Scott; Micela, Giuseppina; Pagano, Isabella; Woodward, Charles E

    2016-01-01

    The demonstration of efficient single-mode fiber (SMF) coupling is a key requirement for the development of a compact, ultra-precise radial velocity (RV) spectrograph. iLocater is a next generation instrument for the Large Binocular Telescope (LBT) that uses adaptive optics (AO) to inject starlight into a SMF. In preparation for commissioning iLocater, a prototype SMF injection system was installed and tested at the LBT in the Y-band (0.970-1.065 $\\mu$m). This system was designed to verify the capability of the LBT AO system as well as characterize on-sky SMF coupling efficiencies. SMF coupling was measured on stars with variable airmasses, apparent magnitudes, and seeing conditions for six half-nights using the Large Binocular Telescope Interferometer. We present the overall optical and mechanical performance of the SMF injection system, including details of the installation and alignment procedure. A particular emphasis is placed on analyzing the instrument's performance as a function of telescope elevation...

  4. Toward a Blind Deep Quality Evaluator for Stereoscopic Images Based on Monocular and Binocular Interactions.

    Science.gov (United States)

    Shao, Feng; Tian, Weijun; Lin, Weisi; Jiang, Gangyi; Dai, Qionghai

    2016-05-01

    During recent years, blind image quality assessment (BIQA) has been intensively studied with different machine learning tools. Existing BIQA metrics, however, do not design for stereoscopic images. We believe this problem can be resolved by separating 3D images and capturing the essential attributes of images via deep neural network. In this paper, we propose a blind deep quality evaluator (DQE) for stereoscopic images (denoted by 3D-DQE) based on monocular and binocular interactions. The key technical steps in the proposed 3D-DQE are to train two separate 2D deep neural networks (2D-DNNs) from 2D monocular images and cyclopean images to model the process of monocular and binocular quality predictions, and combine the measured 2D monocular and cyclopean quality scores using different weighting schemes. Experimental results on four public 3D image quality assessment databases demonstrate that in comparison with the existing methods, the devised algorithm achieves high consistent alignment with subjective assessment. PMID:26960225

  5. Flight testing of a binocular bisensor HMD for helicopter: some human factors aspects

    Science.gov (United States)

    Leger, Alain; Roumes, Corinne; Bergeaud, J. M.; Dareoux, P.; Gardelle, C.

    1998-08-01

    The need for night vision system in military helicopter has been recognized for many years now. Besides fixed FLIR and night vision goggles, helmet-mounted systems coupled with head-slaved IR sensor have been introduced during the last decade in modern attack helicopters. Monocular HMDs have been fielded on the AH-64 and used in operation. Human factors aspects pertaining to such night vision devices has been extensively reviewed and published. Though, full scale flight tests of binocular HMDs with integrated I2 and head coupled IR sensors have rarely been reported. A binocular helmet, with a 40 degree full overlap FOV has been developed under a contract of the French DGA. Two image intensifiers tubes located on each side of the head are integrated on the helmet, which also has full raster and stroke capacity. Both images are projected on the visor of the helmet and collimated to infinity. IR sensor imagery and navigation system are coupled to the helmet using an electro-magnetic head-tracker. Test flight of the helmet have been conducted by the French Flight Test Center on specially equipped Puma test-bed aircraft. Approximately 150 flight hours have been devoted to testing of the helmet, either with I2 and IR sensors.

  6. A high precision instrument to measure angular and binocular deviation introduced by aircraft windscreens by using a shadow casting technique

    International Nuclear Information System (INIS)

    Objects viewed through transparent sheets with residual non-parallelism and irregularity appear shifted and distorted. This distortion is measured in terms of angular and binocular deviation of an object viewed through the transparent sheet. The angular and binocular deviations introduced are particularly important in the context of aircraft windscreens and canopies as they can interfere with decision making of pilots especially while landing, leading to accidents. In this work, we have developed an instrument to measure both the angular and binocular deviations introduced by transparent sheets. This instrument is especially useful in the qualification of aircraft windscreens and canopies. It measures the deviation in the geometrical shadow cast by a periodic dot pattern trans-illuminated by the distorted light beam from the transparent test specimen compared to the reference pattern. Accurate quantification of the shift in the pattern is obtained by cross-correlating the reference shadow pattern with the specimen shadow pattern and measuring the location of the correlation peak. The developed instrument is handy to use and computes both angular and binocular deviation with an accuracy of less than ±0.1 mrad (≈0.036 mrad) and has an excellent repeatability with an error of less than 2%.

  7. FPGA Based High Accuracy Synchronous Acquisition Design for Binocular Vision System

    Directory of Open Access Journals (Sweden)

    Lili Lin

    2011-06-01

    Full Text Available This paper proposes a coarse-to-fine two-level synchronous data acquisition and transmission system for binocular stereo vision, which satisfies strict synchronous requirement of stereo vision. Specifically, this synchronization system design contains: coarse level synchronous based on hardware circuit design and the fine level synchronous based on hardware description language (HDL design. The former includes the synchronization design of clock and external trigger. The latter utilizes a multi-level synchronous control strategy from field-level to pixel-level, which consists of field-synchronous acquisition of the two-channel video inputs, two-channel Ping-pong buffers switch control module, and pixel-synchronous bit-splicing and PCI transmission module. The experiments of synchronous acquisition and display demonstrate the high reliability and great performance of this synchronous system.

  8. An Active System for Visually-Guided Reaching in 3D across Binocular Fixations

    Directory of Open Access Journals (Sweden)

    Ester Martinez-Martin

    2014-01-01

    Full Text Available Based on the importance of relative disparity between objects for accurate hand-eye coordination, this paper presents a biological approach inspired by the cortical neural architecture. So, the motor information is coded in egocentric coordinates obtained from the allocentric representation of the space (in terms of disparity generated from the egocentric representation of the visual information (image coordinates. In that way, the different aspects of the visuomotor coordination are integrated: an active vision system, composed of two vergent cameras; a module for the 2D binocular disparity estimation based on a local estimation of phase differences performed through a bank of Gabor filters; and a robotic actuator to perform the corresponding tasks (visually-guided reaching. The approach’s performance is evaluated through experiments on both simulated and real data.

  9. An active system for visually-guided reaching in 3D across binocular fixations.

    Science.gov (United States)

    Martinez-Martin, Ester; del Pobil, Angel P; Chessa, Manuela; Solari, Fabio; Sabatini, Silvio P

    2014-01-01

    Based on the importance of relative disparity between objects for accurate hand-eye coordination, this paper presents a biological approach inspired by the cortical neural architecture. So, the motor information is coded in egocentric coordinates obtained from the allocentric representation of the space (in terms of disparity) generated from the egocentric representation of the visual information (image coordinates). In that way, the different aspects of the visuomotor coordination are integrated: an active vision system, composed of two vergent cameras; a module for the 2D binocular disparity estimation based on a local estimation of phase differences performed through a bank of Gabor filters; and a robotic actuator to perform the corresponding tasks (visually-guided reaching). The approach's performance is evaluated through experiments on both simulated and real data. PMID:24672295

  10. A binocular pupil model for simulation of relative afferent pupil defects and the swinging flashlight test.

    Science.gov (United States)

    Privitera, Claudio M; Stark, Lawrence W

    2006-03-01

    Many important intracranial neural pathways are involved in the control of the two muscles of the human pupil and the observation and analysis of pupil responses to light or other stimuli is of great interest in many clinical procedures. The binocular pupil model presented in this document has a topology encompassing much of the complexity of the pupil system neurophysiology. The dynamic parameters of the model were matched against pupil experiments under multiple conditions. It is employed here to simulate responses to the swinging flashlight test, a procedure which is routinely practiced in ophthalmology to diagnose different degrees of relative afferent pupil defects often a consequence of severe optic nerve diseases or retinal dysfunctions. Other, not light-dependent, pupil stimuli are briefly discussed. PMID:16404612

  11. Perceptual grouping via binocular disparity: The impact of stereoscopic good continuation.

    Science.gov (United States)

    Deas, Lesley M; Wilcox, Laurie M

    2015-08-01

    Stereoscopic contextual effects are widely reported but are generally discussed in terms of 2-D Gestalt grouping principles, e.g., good continuation or closure. We propose that there are disparity-based grouping operations that are separable from 2-D grouping and instead depend on the distribution of binocular disparity information. Two experiments assess the impact of perceptual grouping via good disparity continuation. First, perceived depth magnitude is reduced for a multidot contour with a smooth disparity gradient compared to the end points in isolation. This reduction is eliminated when disparity jitter is introduced to the intermediate dots. Second, observers showed more efficient visual search for the continuous contour versus the discontinuous version. Therefore, when there is spatial support for interpretation of a slanted object, quantitative depth is reduced, but is rapidly detected in visual search. These results reflect the operation of disparity-based grouping, extending the 2-D principle of good continuation into the third dimension. PMID:26275212

  12. Co-Phasing the Large Binocular Telescope:. [Status and Performance of LBTI-PHASECam

    Science.gov (United States)

    Defrere, D.; Hinz, P.; Downey, E.; Ashby, D.; Bailey, V.; Brusa, G.; Christou, J.; Danchi, W. C.; Grenz, P.; Hill, J. M.; Hoffmann, W. F.; Leisenring, J.; Lozi, J.; McMahon, T.; Mennesson, B.; Millan-Gabet, R.; Montoya, M.; Powell, K.; Skemer, A.; Vaitheeswaran, V.; Vaz, A.; Veillet, C.

    2014-01-01

    The Large Binocular Telescope Interferometer is a NASA-funded nulling and imaging instrument designed to coherently combine the two 8.4-m primary mirrors of the LBT for high-sensitivity, high-contrast, and high-resolution infrared imaging (1.5-13 micrometer). PHASECam is LBTI's near-infrared camera used to measure tip-tilt and phase variations between the two AO-corrected apertures and provide high-angular resolution observations. We report on the status of the system and describe its on-sky performance measured during the first semester of 2014. With a spatial resolution equivalent to that of a 22.8-meter telescope and the light-gathering power of single 11.8-meter mirror, the co-phased LBT can be considered to be a forerunner of the next-generation extremely large telescopes (ELT).

  13. Prevalence of Accommodative and Non-Strabismic Binocular Anomalies in a Puerto Rican Pediatric Population

    Directory of Open Access Journals (Sweden)

    Stefania M. Paniccia, OD, MS

    2015-06-01

    Full Text Available Background: There exists a considerable void in the literature of studies that examine the prevalence of non-strabismic binocular and accommodative disorders in the pediatric population of Puerto Rico. The purpose of this retrospective study was to fill this void by performing a comprehensive record review of the pediatric clinical population of the InterAmerican University College of Optometry satellite clinics. Methods: This study was performed using a random selection of 593 existing health records of patients between the ages of 5 and 20 years. Patients had participated in a complete optometric assessment between the years 2004 and 2012. The criteria for selection were the absence of strabismus, amblyopia, nystagmus, vertical deviation, corneal pathology, retinal pathology, lens pathology, or any other parameter outside of population requirements. Results: Statistical analysis was performed using the IBM SPSS program. Results of this study indicate that the most common non-strabismic and accommodative anomalies in the studied population are accommodative insufficiency (39.0%, convergence insufficiency (12.6%, convergence excess (9.1%, and accommodative infacility (7.6%. Conclusions: Accommodative and non-strabismic binocular vision problems are prevalent in the pediatric population of the InterAmerican satellite clinics. This is the first epidemiologic study about the prevalence of these conditions in Puerto Rico. Due to the possibility of these non-strabismic and accommodative anomalies resulting in a reduced quality of life for children and affecting school performance, sports performance, and play activities, an appropriate vision evaluation, diagnosis, and treatment is important. Lastly, further comprehensive studies should be conducted in Puerto Rico using this study as a base for data collection and analysis.

  14. REDES DE RIVALIDADES Y ALIANZAS ENTRE GRUPOS DE SIMPATIZANTES EN ARGENTINA / Rivalries and alliances networks among supporter’s groups in Argentina.

    Directory of Open Access Journals (Sweden)

    Javier Sebastian Bundio

    2014-12-01

    Full Text Available Con el objetivo de evaluar la influencia de factores tales como la frecuencia de partidos y la cercanía geográfica de instituciones deportivas en el establecimiento de rivalidades y alianzas entre sus grupos de simpatizantes, llevé adelante un Análisis de Redes Sociales a partir de datos para 186 hinchadas argentinas. El conjunto de datos analizados incluye las redes de enemistades (rivalidades mutuamente reconocidas, amistades (afinidades y alianzas mutuamente reconocidas e interacción (cantidad de partidos jugados en los últimos 40 años, y los atributos de pertenencia  provincial y municipal (localización de los estadios. Los resultados obtenidos muestran que la organización regional-nacional de la competencia deportiva, en sus 5 niveles competitivos (Primera A, Nacional B, Primera B, Primera C, Primera D, Argentino A, Argentino B y Argentino C afecta la estructura de las redes de rivalidades y alianzas entre adherentes a equipos de fútbol argentinos. Además detecté una presencia significativa, aunque menor, de tríadas balanceadas de 2 enemistades y 1 amistad lo que permite identificar una “lógica del enemigo común”.   Palabras Claves: fútbol, rivalidad deportiva, alianzas, simpatizantes, análisis de redes sociales.     Abstract In order to evaluate the influence of factors such as frequency of matches played and the geographic proximity of sports institutions in the establishment of rivalries and alliances between soccer supporters, I developed a social network analysis using a dataset for 186 Argentinian hinchadas . The data set includes rivalry's network (rivalries mutually recognized, alliance's network (mutually recognized affinities and alliances and interaction's network (amount of matches played in the last 40 years, and provincial and municipal adscription attributes  (location of stadium. The results show that the regional-national organization of sports competition, in its 5 competitive levels (First A

  15. Psychophysical "blinding" methods reveal a functional hierarchy of unconscious visual processing.

    Science.gov (United States)

    Breitmeyer, Bruno G

    2015-09-01

    Numerous non-invasive experimental "blinding" methods exist for suppressing the phenomenal awareness of visual stimuli. Not all of these suppressive methods occur at, and thus index, the same level of unconscious visual processing. This suggests that a functional hierarchy of unconscious visual processing can in principle be established. The empirical results of extant studies that have used a number of different methods and additional reasonable theoretical considerations suggest the following tentative hierarchy. At the highest levels in this hierarchy is unconscious processing indexed by object-substitution masking. The functional levels indexed by crowding, the attentional blink (and other attentional blinding methods), backward pattern masking, metacontrast masking, continuous flash suppression, sandwich masking, and single-flash interocular suppression, fall at progressively lower levels, while unconscious processing at the lowest levels is indexed by eye-based binocular-rivalry suppression. Although unconscious processing levels indexed by additional blinding methods is yet to be determined, a tentative placement at lower levels in the hierarchy is also given for unconscious processing indexed by Troxler fading and adaptation-induced blindness, and at higher levels in the hierarchy indexed by attentional blinding effects in addition to the level indexed by the attentional blink. The full mapping of levels in the functional hierarchy onto cortical activation sites and levels is yet to be determined. The existence of such a hierarchy bears importantly on the search for, and the distinctions between, neural correlates of conscious and unconscious vision. PMID:25704454

  16. Binocular vision in a virtual world: visual deficits following the wearing of a head-mounted display.

    Science.gov (United States)

    Mon-Williams, M; Wann, J P; Rushton, S

    1993-10-01

    The short-term effects on binocular stability of wearing a conventional head-mounted display (HMD) to explore a virtual reality environment were examined. Twenty adult subjects (aged 19-29 years) wore a commercially available HMD for 10 min while cycling around a computer generated 3-D world. The twin screen presentations were set to suit the average interpupillary distance of our subject population, to mimic the conditions of public access virtual reality systems. Subjects were examined before and after exposure to the HMD and there were clear signs of induced binocular stress for a number of the subjects. The implications of introducing such HMDs into the workplace and entertainment environments are discussed. PMID:8278192

  17. Measuring perceived depth in natural images and study of its relation with monocular and binocular depth cues

    OpenAIRE

    Lebreton, Pierre; Raake, Alexander; Barkowsky, Marcus; Le Callet, Patrick

    2014-01-01

    The perception of depth in images and video sequences is based on different depth cues. Studies have considered depth perception threshold as a function of viewing distance (Cutting & Vishton,1995), the combination of different monocular depth cues and their quantitative relation with binocular depth cues and their different possible type of interactions (Landy,1995). But these studies only consider artificial stimuli and none of them attempts to provide a quantitative contribution of monocular a...

  18. Quantitative visual field assessment of squinting eye under binocular conditions in ten patients with microstrabismus. Preliminary report.

    OpenAIRE

    Joosse, Maurits; Minderhout, H.M. van; Simonsz, Huib; Jong, Paulus

    1994-01-01

    textabstractIntroduction: It is still not exactly known how strabismic patients perceive the surrounding world. It is commonly believed that patients with early onset convergent strabismus and microstrabismus do not suffer from diplopia because of two mechanisms: suppression and anomalous retinal correspondence (ARC). Suppression only occurs under binocular viewing conditions and concerns the central part of the visual field of the strabismic eye. Suppression is associated with a decrease of ...

  19. Measuring perceived depth in natural images and study of its relation with monocular and binocular depth cues

    Science.gov (United States)

    Lebreton, Pierre; Raake, Alexander; Barkowsky, Marcus; Le Callet, Patrick

    2014-03-01

    The perception of depth in images and video sequences is based on different depth cues. Studies have considered depth perception threshold as a function of viewing distance (Cutting and Vishton, 1995), the combination of different monocular depth cues and their quantitative relation with binocular depth cues and their different possible type of interactions (Landy, l995). But these studies only consider artificial stimuli and none of them attempts to provide a quantitative contribution of monocular and binocular depth cues compared to each other in the specific context of natural images. This study targets this particular application case. The evaluation of the strength of different depth cues compared to each other using a carefully designed image database to cover as much as possible different combinations of monocular (linear perspective, texture gradient, relative size and defocus blur) and binocular depth cues. The 200 images were evaluated in two distinct subjective experiments to evaluate separately perceived depth and different monocular depth cues. The methodology and the description of the definition of the different scales will be detailed. The image database (DC3Dimg) is also released for the scientific community.

  20. HIF1α and HIF2α: sibling rivalry in hypoxic tumor growth and progression

    OpenAIRE

    Keith, Brian; Johnson, Randall S; Simon, M. Celeste

    2011-01-01

    Hypoxia inducible factors (HIFs) are broadly expressed in human cancers, and HIF1α and HIF2α were previously suspected of promoting tumor progression through largely overlapping functions. However, this relatively simple model has now been challenged in light of recent data from genome-wide analyses of human tumors, genetically engineered mouse models of cancer, and systems biology approaches that reveal unique and sometimes opposing HIFa activities in both normal physiology and disease. Thes...

  1. PEPSI: The high-resolution echelle spectrograph and polarimeter for the Large Binocular Telescope

    CERN Document Server

    Strassmeier, K G; Järvinen, A; Weber, M; Woche, M; Barnes, S I; Bauer, S -M; Beckert, E; Bittner, W; Bredthauer, R; Carroll, T A; Denker, C; Dionies, F; DiVarano, I; Döscher, D; Fechner, T; Feuerstein, D; Granzer, T; Hahn, T; Harnisch, G; Hofmann, A; Lesser, M; Paschke, J; Pankratow, S; Plank, V; Plüschke, D; Popow, E; Sablowski, D; Storm, J

    2015-01-01

    PEPSI is the bench-mounted, two-arm, fibre-fed and stabilized Potsdam Echelle Polarimetric and Spectroscopic Instrument for the 2x8.4 m Large Binocular Telescope (LBT). Three spectral resolutions of either 43 000, 120 000 or 270 000 can cover the entire optical/red wavelength range from 383 to 907 nm in three exposures. Two 10.3kx10.3k CCDs with 9-{\\mu}m pixels and peak quantum efficiencies of 96 % record a total of 92 echelle orders. We introduce a new variant of a wave-guide image slicer with 3, 5, and 7 slices and peak efficiencies between 96 %. A total of six cross dispersers cover the six wavelength settings of the spectrograph, two of them always simultaneously. These are made of a VPH-grating sandwiched by two prisms. The peak efficiency of the system, including the telescope, is 15% at 650 nm, and still 11% and 10% at 390 nm and 900 nm, respectively. In combination with the 110 m2 light-collecting capability of the LBT, we expect a limiting magnitude of 20th mag in V in the low-resolution mode. The R=...

  2. Precise positioning method for multi-process connecting based on binocular vision

    Science.gov (United States)

    Liu, Wei; Ding, Lichao; Zhao, Kai; Li, Xiao; Wang, Ling; Jia, Zhenyuan

    2016-01-01

    With the rapid development of aviation and aerospace, the demand for metal coating parts such as antenna reflector, eddy-current sensor and signal transmitter, etc. is more and more urgent. Such parts with varied feature dimensions, complex three-dimensional structures, and high geometric accuracy are generally fabricated by the combination of different manufacturing technology. However, it is difficult to ensure the machining precision because of the connection error between different processing methods. Therefore, a precise positioning method is proposed based on binocular micro stereo vision in this paper. Firstly, a novel and efficient camera calibration method for stereoscopic microscope is presented to solve the problems of narrow view field, small depth of focus and too many nonlinear distortions. Secondly, the extraction algorithms for law curve and free curve are given, and the spatial position relationship between the micro vision system and the machining system is determined accurately. Thirdly, a precise positioning system based on micro stereovision is set up and then embedded in a CNC machining experiment platform. Finally, the verification experiment of the positioning accuracy is conducted and the experimental results indicated that the average errors of the proposed method in the X and Y directions are 2.250 μm and 1.777 μm, respectively.

  3. A Real-time Range Finding System with Binocular Stereo Vision

    Directory of Open Access Journals (Sweden)

    Xiao-bo Lai

    2012-05-01

    Full Text Available To acquire range information for mobile robots, a TMS320DM642 DSP‐based range finding system with binocular stereo vision is proposed. Firstly, paired images of the target are captured and a Gaussian filter, as well as improved Sobel kernels, are achieved. Secondly, a feature‐based local stereo matching algorithm is performed so that the space location of the target can be determined. Finally, in order to improve the reliability and robustness of the stereo matching algorithm under complex conditions, the confidence filter and the left‐right consistency filter are investigated to eliminate the mismatching points. In addition, the range finding algorithm is implemented in the DSP/BIOS operating system to gain real‐time control. Experimental results show that the average accuracy of range finding is more than 99% for measuring single‐point distances equal to 120cm in the simple scenario and the algorithm takes about 39ms for ranging a time in a complex scenario. The effectivity, as well as the feasibility, of the proposed range finding system are verified.

  4. Binocular visual tracking and grasping of a moving object with a 3D trajectory predictor

    Directory of Open Access Journals (Sweden)

    J. Fuentes‐Pacheco

    2009-12-01

    Full Text Available This paper presents a binocular eye‐to‐hand visual servoing system that is able to track and grasp a moving object in real time.Linear predictors are employed to estimate the object trajectory in three dimensions and are capable of predicting futurepositions even if the object is temporarily occluded. For its development we have used a CRS T475 manipulator robot with sixdegrees of freedom and two fixed cameras in a stereo pair configuration. The system has a client‐server architecture and iscomposed of two main parts: the vision system and the control system. The vision system uses color detection to extract theobject from the background and a tracking technique based on search windows and object moments. The control system usesthe RobWork library to generate the movement instructions and to send them to a C550 controller by means of the serial port.Experimental results are presented to verify the validity and the efficacy of the proposed visual servoing system.

  5. Large Binocular Telescope Interferometer Adaptive Optics: On-sky performance and lessons learned

    CERN Document Server

    Bailey, Vanessa P; Puglisi, Alfio T; Esposito, Simone; Vaitheeswaran, Vidhya; Skemer, Andrew J; Defrere, Denis; Vaz, Amali; Leisenring, Jarron M

    2014-01-01

    The Large Binocular Telescope Interferometer is a high contrast imager and interferometer that sits at the combined bent Gregorian focus of the LBT's dual 8.4~m apertures. The interferometric science drivers dictate 0.1'' resolution with $10^3-10^4$ contrast at $10~\\mu m$, while the $4~\\mu m$ imaging science drivers require even greater contrasts, but at scales $>$0.2''. In imaging mode, LBTI's Adaptive Optics system is already delivering $4~\\mu m$ contrast of $10^4-10^5$ at $0.3''-0.75''$ in good conditions. Even in poor seeing, it can deliver up to 90\\% Strehl Ratio at this wavelength. However, the performance could be further improved by mitigating Non-Common Path Aberrations. Any NCPA remedy must be feasible using only the current hardware: the science camera, the wavefront sensor, and the adaptive secondary mirror. In preliminary testing, we have implemented an ``eye doctor'' grid search approach for astigmatism and trefoil, achieving 5\\% improvement in Strehl Ratio at $4~\\mu m$, with future plans to tes...

  6. Effects of quantum noise and binocular summation on dose requirements in stereoradiography

    International Nuclear Information System (INIS)

    In the case of a quantum-noise limited detector, signal detection theory suggests that stereoradiographic images can be acquired with one half of the per-image dose needed for a standard radiographic projection, as information from the two stereo images can be combined. Previously, film-screen stereoradiography has been performed using the same per-image dose as in projection radiography, i.e., doubling the total dose. In this paper, the assumption of a possible decrease in dose for stereoradiography was tested by a series of contrast-detail experiments, using phantom images acquired over a range of exposures. The number of visible details, the effective reduction of the dose, and the effective decrease in the threshold signal-to-noise ratio were determined using human observers under several display and viewing conditions. These results were averaged over five observers and compared with multiple readings by a single observer and with the results of an additional observer with limited stereoscopic acuity. Experimental results show that the total dose needed to produce a stereoradiographic image pair is approximately 1.1 times the dose needed for a single projection in standard radiography, indicating that under these conditions the human visual system demonstrates almost ideal binocular summation

  7. Three-dimensional infrared imaging method based on binocular stereo vision

    Science.gov (United States)

    Sun, Junhua; Ma, Haining; Zeng, Debing

    2015-10-01

    The infrared imaging technique is characterized as high-precision and noncontact and provides the temperature information of the object, leading to its broad application in civil and military fields. Currently, the research on infrared thermography is mainly focused on two-dimensional images, lacking the information in depth orientation. To extend the range of application and provide spatial information, a three-dimensional (3-D) infrared imaging system based on binocular stereo vision is presented. The system is composed of two visible-light cameras, an infrared camera, and a digital projector. The proposed system fuses the metric information and the infrared information to acquire the 3-D surface temperature distribution by combining the 3-D reconstruction technique with infrared thermography. The registration of the metric information and the infrared image is accomplished according to the properties of three-view geometry. Experiments have been undertaken with a storage box, a rudder model, and a person's stretching arm, respectively, and the results demonstrated the good performance of the proposed method.

  8. Nulling Data Reduction and On-Sky Performance of the Large Binocular Telescope Interferometer

    CERN Document Server

    Defrère, D; Mennesson, B; Hoffmann, W F; Millan-Gabet, R; Skemer, A J; Bailey, V; Danchi, W C; Downey, E C; Durney, O; Grenz, P; Hill, J M; McMahon, T J; Montoya, M; Spalding, E; Vaz, A; Absil, O; Arbo, P; Bailey, H; Brusa, G; Bryden, G; Esposito, S; Gaspar, A; Haniff, C A; Kennedy, G M; Leisenring, J M; Marion, L; Nowak, M; Pinna, E; Powell, K; Puglisi, A; Rieke, G; Roberge, A; Serabyn, E; Sosa, R; Stapeldfeldt, K; Su, K; Weinberger, A J; Wyatt, M C

    2016-01-01

    The Large Binocular Telescope Interferometer (LBTI) is a versatile instrument designed for high-angular resolution and high-contrast infrared imaging (1.5-13 microns). In this paper, we focus on the mid-infrared (8-13 microns) nulling mode and present its theory of operation, data reduction, and on-sky performance as of the end of the commissioning phase in March 2015. With an interferometric baseline of 14.4 meters, the LBTI nuller is specifically tuned to resolve the habitable zone of nearby main-sequence stars, where warm exozodiacal dust emission peaks. Measuring the exozodi luminosity function of nearby main-sequence stars is a key milestone to prepare for future exoEarth direct imaging instruments. Thanks to recent progress in wavefront control and phase stabilization, as well as in data reduction techniques, the LBTI demonstrated in February 2015 a calibrated null accuracy of 0.05% over a three-hour long observing sequence on the bright nearby A3V star beta Leo. This is equivalent to an exozodiacal dis...

  9. Eyepiece-type full-color electro-holographic display for binocular vision

    Science.gov (United States)

    Yoneyama, Takuo; Yang, Chanyoung; Sakamoto, Yuji; Okuyama, Fumio

    2013-03-01

    Head-mounted type 3-D displays are expected to be useful with Augmented Reality techniques to provide visual information. However, because these displays use the stereoscopic method to provide 3-D vision, observers tend to experience eye discomfort when viewing 3-D images due to the disparity between accommodation and convergence. Electro-holography is a rival technique that displays holograms on electrical devices such as a spatial light modulator and enables observers to view ideal 3-D images in comfort for many hours. In the current study, we applied the holography technique to an eyepiece-type display in order to solve the disparity problem. Our system can represent 3-D images at arbitrary depths and displays large reconstructed images by using a Fourier transform optical system. We also adopted the time division color method to reconstruct full-color images. In computer generated holography, holograms for each color are calculated considering with the distance between their wavelength. In this paper, we describe our calculation algorithm and report the fabrication of an eyepiecetype full color electro-holographic display for binocular vision. To confirm the effectiveness of the proposed system, the reconstructed images were evaluated both objectively and subjectively. Results of experiments show that reconstructed full-color images are located at the correct depth.

  10. A wearable infrared video pupillography with multi-stimulation of consistent illumination for binocular pupil response

    Science.gov (United States)

    Mang, Ou-Yang; Ko, Mei Lan; Tsai, Yi-Chun; Chiou, Jin-Chern; Huang, Ting-Wei

    2016-03-01

    The pupil response to light can reflect various kinds of diseases which are related to physiological health. Pupillary abnormalities may be influenced on people by autonomic neuropathy, glaucoma, diabetes, genetic diseases, and high myopia. In the early stage of neuropathy, it is often asymptomatic and difficulty detectable by ophthalmologists. In addition, the position of injured nerve can lead to unsynchronized pupil response for human eyes. In our study, we design the pupilometer to measure the binocular pupil response simultaneously. It uses the different wavelength of LEDs such as white, red, green and blue light to stimulate the pupil and record the process. Therefore, the pupilometer mainly contains two systems. One is the image acquisition system, it use the two cameras modules with the same external triggered signal to capture the images of the pupil simultaneously. The other one is the illumination system. It use the boost converter ICs and LED driver ICs to supply the constant current for LED to maintain the consistent luminance in each experiments for reduced experimental error. Furthermore, the four infrared LEDs are arranged nearby the stimulating LEDs to illuminate eyes and increase contrast of image for image processing. In our design, we success to implement the function of synchronized image acquisition with the sample speed in 30 fps and the stable illumination system for precise measurement of experiment.

  11. Investigating binocular summation in human vision using complementary fused external noise

    Science.gov (United States)

    Howell, Christopher L.; Olson, Jeffrey T.

    2016-05-01

    The impact noise has on the processing of visual information at various stages within the human visual system (HVS) is still an open research area. To gain additional insight, twelve experiments were administered to human observers using sine wave targets to determine their contrast thresholds. A single frame of additive white Gaussian noise (AWGN) and its complement were used to investigate the effect of noise on the summation of visual information within the HVS. A standard contrast threshold experiment served as the baseline for comparisons. In the standard experiment, a range of sine wave targets are shown to the observers and their ability to detect the targets at varying contrast levels were recorded. The remaining experiments added some form of noise (noise image or its complement) and/or an additional sine wave target separated between one to three octaves to the test target. All of these experiments were tested using either a single monitor for viewing the targets or with a dual monitor presentation method for comparison. In the dual monitor experiments, a ninety degree mirror was used to direct each target to a different eye, allowing for the information to be fused binocularly. The experiments in this study present different approaches for delivering external noise to the HVS, and should allow for an improved understanding regarding how noise enters the HVS and what impact noise has on the processing of visual information.

  12. Structural Parameters Calibration for Binocular Stereo Vision Sensors Using a Double-Sphere Target.

    Science.gov (United States)

    Wei, Zhenzhong; Zhao, Kai

    2016-01-01

    Structural parameter calibration for the binocular stereo vision sensor (BSVS) is an important guarantee for high-precision measurements. We propose a method to calibrate the structural parameters of BSVS based on a double-sphere target. The target, consisting of two identical spheres with a known fixed distance, is freely placed in different positions and orientations. Any three non-collinear sphere centres determine a spatial plane whose normal vector under the two camera-coordinate-frames is obtained by means of an intermediate parallel plane calculated by the image points of sphere centres and the depth-scale factors. Hence, the rotation matrix R is solved. The translation vector T is determined using a linear method derived from the epipolar geometry. Furthermore, R and T are refined by nonlinear optimization. We also provide theoretical analysis on the error propagation related to the positional deviation of the sphere image and an approach to mitigate its effect. Computer simulations are conducted to test the performance of the proposed method with respect to the image noise level, target placement times and the depth-scale factor. Experimental results on real data show that the accuracy of measurement is higher than 0.9‰, with a distance of 800 mm and a view field of 250 × 200 mm². PMID:27420063

  13. Differences of accommodative responses between two eyes under binocular viewing condition mediated by polarizing glasses

    Directory of Open Access Journals (Sweden)

    Rui-Qing Wang

    2016-04-01

    Full Text Available AIM:To study the differences of accommodative responses between the two eyes under 3 different polarized viewing conditions. METHODS:Fifteen volunteers with emmetrope were recruited into this study(aged 18~38, 6 males and 9 females. Three different viewing conditions were set up by using polarizing glasses and liquid crystal display:(1right eye could see the visual target on the screen, but left eye cannot see it;(2left eye could see the visual target on the screen, but right eye cannot see it;(3both eyes could see the target. Accommodative responses were measured by infrared auto-refractor when fixating at the target at 5, 2, 1, 0.5 and 0.33m under the above 3 viewing conditions. The differences of accommodative responses under different viewing conditions were compared by using variance analysis of repeated measuring and t test. RESULTS:Significant differences of accommodative responses between the two eyes were found under condition(1and(2at all the fixating distance. The accommodative responses in used eyes which can see the visual target were higher than in non-used eyes which cannot see the visual target(PP>0.05. CONCLUSION:Ciliary muscles in the used eyes were more relatively tonic than non-used eyes under binocular open viewing condition. The imbalance of accommodative responses between two eyes may be one of the risk factors resulting into the occurrence of myopia.

  14. Large Binocular Telescope Adaptive Optics System: New achievements and perspectives in adaptive optics

    CERN Document Server

    Esposito, Simone; Pinna, Enrico; Puglisi, Alfio; Quirós-Pacheco, Fernando; Arcidiacono, Carmelo; Xompero, Marco; Briguglio, Runa; Agapito, Guido; Busoni, Lorenzo; Fini, Luca; Argomedo, Javier; Gherardi, Alessandro; Brusa, Guido; Miller, Douglas; Guerra, Juan Carlos; Stefanini, Paolo; Salinari, Piero; 10.1117/12.898641

    2012-01-01

    The Large Binocular Telescope (LBT) is a unique telescope featuring two co-mounted optical trains with 8.4m primary mirrors. The telescope Adaptive Optics (AO) system uses two innovative key components, namely an adaptive secondary mirror with 672 actuators and a high-order pyramid wave-front sensor. During the on-sky commissioning such a system reached performances never achieved before on large ground-based optical telescopes. Images with 40mas resolution and Strehl Ratios higher than 80% have been acquired in H band (1.6 micron). Such images showed a contrast as high as 10e-4. Based on these results, we compare the performances offered by a Natural Guide Star (NGS) system upgraded with the state-of-the-art technology and those delivered by existing Laser Guide Star (LGS) systems. The comparison, in terms of sky coverage and performances, suggests rethinking the current role ascribed to NGS and LGS in the next generation of AO systems for the 8-10 meter class telescopes and Extremely Large Telescopes (ELTs)...

  15. Calibração binocular com gabaritos 1D sem restrição demovimentos Binocular calibration with 1D parttern without movements restriction

    Directory of Open Access Journals (Sweden)

    José Alexandre de França

    2011-06-01

    Full Text Available Na visão computacional, a calibração de câmeras é um processo necessário quando deseja-se recuperar informações como, por exemplo, ângulos e distâncias. O presente trabalho trata do problema de calibração de câmeras com gabaritos de uma única dimensão. Atualmente, tal problema só tem solução se forem impostas restrições ao movimento do gabarito ou se alguns parâmetros das câmeras já sejam previamente conhecidos. Contudo, demonstra-se que uma abordagem diferente pode ser aplicada se, ao invés de uma única câmera, um conjunto binocular for considerado. Nesse caso, a calibração é possível com um gabarito 1D que realiza um deslocamento desconhecido e sem restrições, mesmo sem nenhuma informação prévia a respeito das câmeras. Tal método baseia-se na estimação de uma transformação que, após a estimação da matriz fundamental do sistema, permite atualizar uma calibração projetiva para uma calibração euclidiana. Experimentos em imagens reais e sintéticas validam o novo método e mostram que a sua exatidão é comparável a de outros métodos clássicos de calibração, já bem conhecidos na literatura.In computer vision, the camera calibration is a process needed when the recovery of some information, such as angles and distances, is desired. The present work deals with the problem of camera calibration using one-dimensional patterns. Nowadays, this problem only has a solution if some restrictions to the pattern's movement are imposed or if some angles of the cameras are known in advance. However, a different approach can be applied if, instead of only one camera, a stereo system is considered. In that case, the calibration is possible with a one-dimensional pattern that executes an unknown and unrestricted movement, even without any previous information concerning the cameras. Such method is based on the estimation of a transform which, after the estimation of the system's fundamental matrix, allows

  16. HIF1α and HIF2α: sibling rivalry in hypoxic tumour growth and progression.

    Science.gov (United States)

    Keith, Brian; Johnson, Randall S; Simon, M Celeste

    2012-01-01

    Hypoxia-inducible factors (HIFs) are broadly expressed in human cancers, and HIF1α and HIF2α were previously suspected to promote tumour progression through largely overlapping functions. However, this relatively simple model has now been challenged in light of recent data from various approaches that reveal unique and sometimes opposing activities of these HIFα isoforms in both normal physiology and disease. These effects are mediated in part through the regulation of unique target genes, as well as through direct and indirect interactions with important oncoproteins and tumour suppressors, including MYC and p53. As HIF inhibitors are currently undergoing clinical evaluation as cancer therapeutics, a more thorough understanding of the unique roles performed by HIF1α and HIF2α in human neoplasia is warranted. PMID:22169972

  17. Binocular vision and abnormal head posture in children when watching television

    Science.gov (United States)

    Zhang, Di; Zhang, Wei-Hong; Dai, Shu-Zhen; Peng, Hai-Ying; Wang, Li-Ya

    2016-01-01

    AIM To determine the association between the binocular vision and an abnormal head posture (AHP) when watching television (TV) in children 7-14y of age. METHODS Fifty normal children in the normal group and 52 children with an AHP when watching TV in the AHP group were tested for spherical equivalents, far and near fusional convergence (FC) and fusional divergence (FD) amplitudes, near point of convergence, far and near heterophoria, accommodative convergence/ accommodation ratio and stereoacuity. The values of these tests were compared between the two groups. The independent t test was applied at a confidence level of 95%. RESULTS The far and near FC amplitudes and far FD amplitudes were lower in the AHP group (the far FC amplitudes: break point 13.6±5.4Δ, recovery point 8.7±5.4Δ. The near FC amplitudes: break point 14.5±7.3Δ, recovery point 10.3±5.1Δ. The far FD amplitudes: break point 3.9±2.7Δ, recovery point 2.6±2.3Δ) compared with those in the normal group (the far FC amplitudes: break point 19.1±6.2Δ, recovery point 12.4±4.5Δ. The near FC amplitudes: break point 22.3±8.0Δ, recovery point 16.1±5.7Δ. The far FD amplitudes: break point 7.0±2.1Δ, recovery point 4.6±1.9Δ). Other tests presented no statistically significant differences. CONCLUSION An association between the reduced FC and FD amplitudes and the AHP in children when watching TV is proposed in the study. This kind of AHP is considered to be an anomalous manifestation which appears in a part of puerile patients of fusional vergence dysfunction. PMID:27275434

  18. Computer-enhanced stereoscopic vision in a head-mounted operating binocular

    International Nuclear Information System (INIS)

    Based on the Varioscope, a commercially available head-mounted operating binocular, we have developed the Varioscope AR, a see through head-mounted display (HMD) for augmented reality visualization that seamlessly fits into the infrastructure of a surgical navigation system. We have assessed the extent to which stereoscopic visualization improves target localization in computer-aided surgery in a phantom study. In order to quantify the depth perception of a user aiming at a given target, we have designed a phantom simulating typical clinical situations in skull base surgery. Sixteen steel spheres were fixed at the base of a bony skull, and several typical craniotomies were applied. After having taken CT scans, the skull was filled with opaque jelly in order to simulate brain tissue. The positions of the spheres were registered using VISIT, a system for computer-aided surgical navigation. Then attempts were made to locate the steel spheres with a bayonet probe through the craniotomies using VISIT and the Varioscope AR as a stereoscopic display device. Localization of targets 4 mm in diameter using stereoscopic vision and additional visual cues indicating target proximity had a success rate (defined as a first-trial hit rate) of 87.5%. Using monoscopic vision and target proximity indication, the success rate was found to be 66.6%. Omission of visual hints on reaching a target yielded a success rate of 79.2% in the stereo case and 56.25% with monoscopic vision. Time requirements for localizing all 16 targets ranged from 7.5 min (stereo, with proximity cues) to 10 min (mono, without proximity cues). Navigation error is primarily governed by the accuracy of registration in the navigation system, whereas the HMD does not appear to influence localization significantly. We conclude that stereo vision is a valuable tool in augmented reality guided interventions. (note)

  19. Multi-laser-guided adaptive optics for the Large Binocular Telescope

    Science.gov (United States)

    Lloyd-Hart, M.; Angel, R.; Green, R.; Stalcup, T.; Milton, N. M.; Powell, K.

    2007-09-01

    We describe the conceptual design of an advanced laser guide star facility (LGSF) for the Large Binocular Telescope (LBT), to be built in collaboration with the LBT's international partners. The highest priority goal for the facility is the correction of ground-layer turbulence, providing partial seeing compensation in the near IR bands over a 4' field. In the H band, GLAO is projected to improve the median seeing from 0.55" to 0.2". The new facility will build on the LBT's natural guide star AO system, integrated into the telescope with correction by adaptive secondary mirrors, and will draw on Arizona's experience in the construction of the first multi-laser adaptive optics (AO) system at the 6.5 m MMT. The LGSF will use four Rayleigh beacons at 532 nm, projected to an altitude of 25 km, on each of the two 8.4 m component telescopes. Initial use of the system for ground layer correction will deliver image quality well matched to the LBT's two LUCIFER near IR instruments. They will be used for direct imaging over a 4'×4' field and will offer a unique capability in high resolution multi-object spectroscopy. The LGSF is designed to include long-term upgrade paths. Coherent imaging at the combined focus of the two apertures will be exploited by the LBT Interferometer in the thermal IR. Using the same launch optics, an axial sodium or Rayleigh beacon can be added to each constellation, for tomographic wavefront reconstruction and diffraction limited imaging over the usual isoplanatic patch. In the longer term, a second DM conjugated to high altitude is foreseen for the LBT's LINC-NIRVANA instrument, which would extend the coherent diffraction-limited field to an arcminute in diameter with multi-conjugate AO.

  20. Are the neural correlates of conscious contents stable or plastic?

    DEFF Research Database (Denmark)

    Sandberg, Kristian; Overgaard, Morten; Rees, Geraint

    2012-01-01

    examine the second assumption. We recorded the magnetoencephalographic (MEG) signal from healthy human participants while they viewed an intermittently presented binocular rivalry stimulus consisting of a face and a grating. During binocular rivalry, the stimulus is kept constant, but the conscious...

  1. Near Point of Convergence Break for Different Age Groups in Turkish Population with Normal Binocular Vision: Normative Data

    Directory of Open Access Journals (Sweden)

    Nihat Sayın

    2013-12-01

    Full Text Available Purpose: The purpose of this study was to evaluate the near point of convergence break in Turkish population with normal binocular vision and to obtain the normative data for the near point of convergence break in different age groups. Such database has not been previously reported. Material and Method: In this prospective study, 329 subjects with normal binocular vision (age range, 3-72 years were evaluated. The near point of convergence break was measured 4 times repeatedly with an accommodative target. Mean values of near point of convergence break were provided for these age groups (≤10, 11-20, 21-30, 31-40, 41-50, 51-60, and >60 years old. A statistical comparison (one-way ANOVA and post-hoc test of these values between age groups was performed. A correlation between the near point of convergence break and age was evaluated by Pearson’s correlation test. Results: The mean value for near point of convergence break was 2.46±1.88 (0.5-14 cm. Specifically, 95% of measurements in all subjects were 60 year-old age groups in the near point of convergence break values (p=0.0001, p=0.0001, p=0.006, p=0.001, p= 0.004. A mild positive correlation was observed between the increase in near point of convergence break and increase of age (r=0.355 (p<0.001. Discussion: The values derived from a relatively large study population to establish a normative database for the near point of convergence break in the Turkish population with normal binocular vision are in relevance with age. This database has not been previously reported. (Turk J Ophthalmol 2013; 43: 402-6

  2. Metabolic changes in the visual cortex of binocular blindness macaque monkeys: a proton magnetic resonance spectroscopy study.

    Directory of Open Access Journals (Sweden)

    Lingjie Wu

    Full Text Available PURPOSE: To evaluate proton magnetic resonance spectroscopy ((1H-MRS in a study of cross-modal plasticity in the visual cortex of binocular blindness macaque monkeys. MATERIALS AND METHODS: Four healthy neonatal macaque monkeys were randomly divided into 2 groups, with 2 in each group. Optic nerve transection was performed in both monkeys in the experimental group (group B to obtain binocular blindness. Two healthy macaque monkeys served as a control group (group A. After sixteen months post-procedure, (1H-MRS was performed in the visual cortex of all monkeys. We compared the peak areas of NAA, Cr, Cho, Glx and Ins and the ratios of NAA/Cr, Cho/Cr, Glx/Cr and Ins/Cr of each monkey in group B with group A. RESULTS: The peak area of NAA and the NAA/Cr ratio in the visual cortex of monkey 4 in group B were found to be dramatically decreased, the peak area of NAA slightly decreased and the NAA/Cr ratio clearly decreased in visual cortex of monkey 3 in group B than those in group A. The peak area of Ins and the Ins/Cr ratio in the visual cortex of monkey 4 in group B slightly increased. The peak area of Cho and the Cho/Cr ratio in the visual cortex of all monkeys in group B dramatically increased compared with group A. The peak area of Glx in the visual cortex of all monkeys in group B slightly increased compared with group A. CONCLUSIONS: (1H-MRS could detect biochemical and metabolic changes in the visual cortex and therefore this technique can be used to provide valuable information for investigating the mechanisms of cross-modal plasticity of binocular blindness in a macaque monkey model.

  3. Infrared Narrowband Tomography of the Local Starburst NGC 1569 with the Large Binocular Telescope/LUCIFER

    Science.gov (United States)

    Pasquali, A.; Bik, A.; Zibetti, S.; Ageorges, N.; Seifert, W.; Brandner, W.; Rix, H.-W.; Jütte, M.; Knierim, V.; Buschkamp, P.; Feiz, C.; Gemperlein, H.; Germeroth, A.; Hofmann, R.; Laun, W.; Lederer, R.; Lehmitz, M.; Lenzen, R.; Mall, U.; Mandel, H.; Müller, P.; Naranjo, V.; Polsterer, K.; Quirrenbach, A.; Schäffner, L.; Storz, C.; Weiser, P.

    2011-04-01

    We used the near-IR imager/spectrograph LUCIFER mounted on the Large Binocular Telescope to image, with subarcsecond seeing, the local dwarf starburst NGC 1569 in the JHK bands and He I 1.08 μm, [Fe II] 1.64 μm, and Brγ narrowband filters. We obtained high-quality spatial maps of He I 1.08 μm, [Fe II] 1.64 μm, and Brγ emission across the galaxy, and used them together with Hubble Space Telescope/Advanced Camera for Surveys images of NGC 1569 in the Hα filter to derive the two-dimensional spatial map of the dust extinction and surface star formation rate (SFR) density. We show that dust extinction (as derived from the Hα/Brγ flux ratio) is rather patchy and, on average, higher in the northwest (NW) portion of the galaxy (E g(B - V) ~= 0.71 mag) than in the southeast (E g(B - V) ~= 0.57 mag). Similarly, the surface density of SFR (computed from either the dereddened Hα or dereddened Brγ image) peaks in the NW region of NGC 1569, reaching a value of about 4 × 10-6 M sun yr-1 pc-2. The total SFR as estimated from the integrated, dereddened Hα (or, alternatively, Brγ) luminosity is about 0.4 M sun yr-1, and the total supernova rate from the integrated, dereddened [Fe II] 1.64 μm luminosity is about 0.005 yr-1 (assuming a distance of 3.36 Mpc). The azimuthally averaged [Fe II] 1.64 μm/Brγ flux ratio is larger at the edges of the central, gas-deficient cavities (encompassing the superstar clusters A and B) and in the galaxy outskirts. If we interpret this line ratio as the ratio between the average past star formation (as traced by supernovae) and ongoing activity (represented by OB stars able to ionize the interstellar medium), it would then indicate that star formation has been quenched within the central cavities and lately triggered in a ring around them. The number of ionizing hydrogen and helium photons as computed from the integrated, dereddened Hα and He I 1.08 μm luminosities suggests that the latest burst of star formation occurred about 4 Myr

  4. INFRARED NARROWBAND TOMOGRAPHY OF THE LOCAL STARBURST NGC 1569 WITH THE LARGE BINOCULAR TELESCOPE/LUCIFER

    International Nuclear Information System (INIS)

    We used the near-IR imager/spectrograph LUCIFER mounted on the Large Binocular Telescope to image, with subarcsecond seeing, the local dwarf starburst NGC 1569 in the JHK bands and He I 1.08 μm, [Fe II] 1.64 μm, and Brγ narrowband filters. We obtained high-quality spatial maps of He I 1.08 μm, [Fe II] 1.64 μm, and Brγ emission across the galaxy, and used them together with Hubble Space Telescope/Advanced Camera for Surveys images of NGC 1569 in the Hα filter to derive the two-dimensional spatial map of the dust extinction and surface star formation rate (SFR) density. We show that dust extinction (as derived from the Hα/Brγ flux ratio) is rather patchy and, on average, higher in the northwest (NW) portion of the galaxy (Eg(B - V) ≅ 0.71 mag) than in the southeast (Eg(B - V) ≅ 0.57 mag). Similarly, the surface density of SFR (computed from either the dereddened Hα or dereddened Brγ image) peaks in the NW region of NGC 1569, reaching a value of about 4 x 10-6 Msun yr-1 pc-2. The total SFR as estimated from the integrated, dereddened Hα (or, alternatively, Brγ) luminosity is about 0.4 Msun yr-1, and the total supernova rate from the integrated, dereddened [Fe II] 1.64 μm luminosity is about 0.005 yr-1 (assuming a distance of 3.36 Mpc). The azimuthally averaged [Fe II] 1.64 μm/Brγ flux ratio is larger at the edges of the central, gas-deficient cavities (encompassing the superstar clusters A and B) and in the galaxy outskirts. If we interpret this line ratio as the ratio between the average past star formation (as traced by supernovae) and ongoing activity (represented by OB stars able to ionize the interstellar medium), it would then indicate that star formation has been quenched within the central cavities and lately triggered in a ring around them. The number of ionizing hydrogen and helium photons as computed from the integrated, dereddened Hα and He I 1.08 μm luminosities suggests that the latest burst of star formation occurred about 4 Myr

  5. Altered GABAergic markers, increased binocularity and reduced plasticity in the visual cortex of Engrailed-2 knockout mice

    Directory of Open Access Journals (Sweden)

    Manuela Allegra

    2014-06-01

    Here we studied GABAergic markers and cortical function in En2-/- mice, by exploiting the well-known anatomical and functional features of the mouse visual system. En2 is expressed in the visual cortex at postnatal day 30 and during adulthood. When compared to age-matched En2+/+ controls, En2-/- mice showed an increased number of parvalbumin (PV+, somatostatin (SOM+ and neuropeptide Y (NPY+ positive interneurons in the visual cortex at P30, and a decreased number of SOM+ and NPY+ interneurons in the adult. At both ages, the differences in distinct interneuron populations observed between En2+/+ and En2-/- mice were layer-specific. Adult En2-/- mice displayed a normal eye-specific segregation in the retino-geniculate pathway, and in vivo electrophysiological recordings showed a normal development of basic functional properties (acuity, response latency, receptive field size of the En2-/- primary visual cortex. However, a significant increase of binocularity was found in P30 and adult En2-/- mice, as compared to age-matched controls. Differently from what observed in En2+/+ mice, the En2-/- primary visual cortex did not respond to a brief monocular deprivation performed between P26 and P29, during the so-called “critical period”. These data suggest that altered GABAergic circuits impact baseline binocularity and plasticity in En2-/- mice, while leaving other visual functional properties unaffected.

  6. Functional MRI activity in the thalamus and occipital cortex of anesthetized dogs induced by monocular and binocular stimulation.

    Science.gov (United States)

    Willis, C K; Quinn, R P; McDonell, W M; Gati, J; Partlow, G; Vilis, T

    2001-07-01

    The neuroanatomy of the mammalian visual system has received considerable attention through electrophysiological study of cats and non-human primates, and through neuroimaging of humans. Canine neuroanatomy, however, has received much less attention, limiting our understanding of canine vision and visual pathways. As an early step in applying blood oxygenation level dependant (BOLD) functional magnetic resonance imaging (fMRI) for veterinary use, we compared visual activity in the thalamus and occipital cortex of anesthetized dogs presented with binocular and monocular visual stimuli. Activity in the left and right thalamus and occipital cortex during monocular stimulation was also compared. Six beagles were presented with a vertical grating visual stimulus and scanned at 4 Tesla. Each dog was scanned twice under each of 3 anesthetic protocols (isoflurane, propofol, and fentanyl/midazolam). We found: 1) significant BOLD activation in the lateral geniculate nucleus (LGN) of the thalamus and the occipital cortex; 2) a significantly larger area of activation in the LGN during monocular stimulation than during binocular stimulation; and 3) that activity in the hemisphere contralateral to the stimulus was not significantly greater than that ipsilateral to it. PMID:11480525

  7. Sibling Rivalry (For Parents)

    Science.gov (United States)

    ... a child's special needs due to illness or learning/emotional issues may require more parental time. Other kids ... again. If you want to make this a learning experience, wait until the emotions have died down. Don't put too much ...

  8. Cooperation or Silent Rivalry?

    DEFF Research Database (Denmark)

    Zank, Wolfgang

    2010-01-01

    on an increasingly institutionalized basis. In terms of military cooperation the US is still the partner for Egypt. But outside the military sphere institutionalized cooperation is comparatively week. In particular the failure of the US to conclude a free-trade agreement has been crucial. But it...

  9. 基于 OpenCV 的双目摄像机标定技术研究%Binocular Camera Calibration Technique Based on OpenCV

    Institute of Scientific and Technical Information of China (English)

    王长元; 邢世蒙

    2014-01-01

    摄像机标定技术作为双目立体视觉领域的一个基础性研究课题,具有很大的理论研究价值和实际应用价值。论文围绕双目立体视觉中的双目摄像机标定技术,分析基于OpenCV的双目摄像机标定的方法。基于OpenCV的双目摄像机标定比传统的定标技术更为灵活,并且具有不错的定标精度。%As a foundational research in the field of binocular stereo vision ,camera calibration technique has great theo‐retical value and practical value .This paper focuses on the binocular stereo vision camera calibration technique to analyze the binocular camera calibration method based on OpenCV .OpenCV camera calibration based on binocular is more flexible than traditional scaling techniques ,and has a good calibration accuracy .

  10. 基于 OpenCV 的双目摄像机标定技术研究%Binocular Camera Calibration Technique Based on OpenCV

    Institute of Scientific and Technical Information of China (English)

    王长元; 邢世蒙

    2014-01-01

    As a foundational research in the field of binocular stereo vision ,camera calibration technique has great theo‐retical value and practical value .This paper focuses on the binocular stereo vision camera calibration technique to analyze the binocular camera calibration method based on OpenCV .OpenCV camera calibration based on binocular is more flexible than traditional scaling techniques ,and has a good calibration accuracy .%摄像机标定技术作为双目立体视觉领域的一个基础性研究课题,具有很大的理论研究价值和实际应用价值。论文围绕双目立体视觉中的双目摄像机标定技术,分析基于OpenCV的双目摄像机标定的方法。基于OpenCV的双目摄像机标定比传统的定标技术更为灵活,并且具有不错的定标精度。

  11. 双目视觉的立体标定方法%Stereo calibration method of binocular vision

    Institute of Scientific and Technical Information of China (English)

    刘俸材; 谢明红; 王伟

    2011-01-01

    为实现双目视觉系统的立体标定,分析了摄像机成像模型,并充分考虑了透镜的径向畸变和切向畸变,提出了一种新的立体标定算法.该算法利用张正友的灵活标定算法,初步求取摄像机的内参数,结合Brown算法并提取图像中角点的子像素级坐标,精确求取摄像机内参数和畸变向量.为方便后续的图像校正,基于前面的单个摄像机标定,通过计算空间中的景物点在左右摄像机成像平面上盼位置关系,计算出双目视觉系统中两个摄像机之间的旋转矩阵R和平移向量T,从而实现了立体标定.实验结果表明,该算法能取得较高的精度,可以应用于双目视觉系统.%In order to realize stereo calibration for binocular vision system, firstly, the image model of camera with a full consideration of radial distortion and tangential distortion of lens is analyzed, and a new method of stereo calibration is proposed. The flexible calibration method of Zhang Zhengyou is used to achieve the initial value of the camera's intrinsic parameters, and combined with the arithmetic of Brown, sub-pixel coordinates of images' comer point are extracted. Through this method, it calculates the intrinsic parameters and distortion vector accurately. Hereafter, based on the single camera calibration aforementioned and calculation of the position relationship of spatial point projected to the left and right cameras' imaging planes which helps to work out the rotation matrix R and translation vector T between the two cameras of the binocular stereo vision system, finally the stereo calibration is achieved. All experimental results show that this calculation method acquires higher precision, and can be applied to binocular system.

  12. Phase-Based Binocular Perception of Motion in Depth: Cortical-Like Operators and Analog VLSI Architectures

    Directory of Open Access Journals (Sweden)

    Silvio P. Sabatini

    2003-06-01

    Full Text Available We present a cortical-like strategy to obtain reliable estimates of the motions of objects in a scene toward/away from the observer (motion in depth, from local measurements of binocular parameters derived from direct comparison of the results of monocular spatiotemporal filtering operations performed on stereo image pairs. This approach is suitable for a hardware implementation, in which such parameters can be gained via a feedforward computation (i.e., collection, comparison, and punctual operations on the outputs of the nodes of recurrent VLSI lattice networks, performing local computations. These networks act as efficient computational structures for embedded analog filtering operations in smart vision sensors. Extensive simulations on both synthetic and real-world image sequences prove the validity of the approach that allows to gain high-level information about the 3D structure of the scene, directly from sensorial data, without resorting to explicit scene reconstruction.

  13. Performance and results from the commissioning of the first acquisition, guiding, and wavefront sensing units for the Large Binocular Telescope

    Science.gov (United States)

    Storm, Jesper; Hill, John; Miller, Douglas; Rakich, Andrew; Thompson, David; Brynnel, Joar; Hahn, Thomas; Heidt, Jochen; Popow, Emil

    2010-07-01

    We present the results from the commisioning of the first three off-axis Acquisition, Guiding and Wavefront Sensing Units on the Large Binocular Telescope. In particular we report on the performance of the units with respect to image quality, optical efficiency and scattered light. We also present the procedure for calibrating the stage coordinate system astrometrically to the focal plane coordinates of the telescope as well as the positional performance of the system. The first of a total of four units was mounted on the telescope in October 2007 and in the mean time three units have been mounted on the telescope. The units have been used for commisioning of the focal stations as well as for scientific observations since the end of 2008 with LUCIFER-I, the near-IR images and MOS spectrograph

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Binocular stereo vision navigation for electric VTOL aircraft%电动VTOL飞行器双目立体视觉导航方法

    Institute of Scientific and Technical Information of China (English)

    张博翰; 蔡志浩; 王英勋

    2011-01-01

    A stereo vision-based navigation method for the electric vertical take-off and landing(VTOL) aircraft to wander safely through an unknown dynamic indoor corridor was researched.The aircraft uses two cameras to obtain images from different locations,and then the theory of binocular stereo vision was used to restore the 3-D coordinates of the feature points in front of the aircraft.Corner matching method was applied to calculate the disparity of the detected corners on the wall.Thus,the horizontal position of unmanned aerial vehicle(UAV) in the corridor was revealed.The area-based stereo matching algorithm was presented to get the dense disparity map of the original image pair,then obstacles were extracted from the disparity map and the navigation points were generated for the UAV to avoid obstacles.Preliminary experiment shows that the method is feasible and can be used as a basis for further research.%研究了在未知的、动态的室内走廊环境中,采用双目立体视觉引导电动VTOL(Vertical Take-Off and Landing)飞行器安全飞行的方法.使用安装在飞机上的两个微型摄像头从不同的位置获取图像,由双目立体视觉理论恢复其周围环境特征点的三维坐标.采用角点匹配方法计算视差,实现无人机在走廊中的横向坐标定位.采用区域灰度相关算法进行立体匹配获取视差图,从视差图上检测出障碍物,并给出避障导航点.初步实验验证表明,该方法可行性较高,可以作为进一步研究的基础.

  16. Disfunciones visuo-perceptivas, oculomotoras, acomodativas y binoculares en niños con trastornos por déficit de atención e hiperactividad

    OpenAIRE

    Pardo Pérez, María Carmen

    2009-01-01

    1) Determinar el grado de desarrollo de las habilidades visuoperceptivas, oculomotoras, acomodativas y binoculares en estudiantes con TDAH. 2) Comparar las habilidades visuales y visuoperceptivas entre un grupo de estudiantes con TDAH y otro que no presenta este trastorno. 3) Analizar qué habilidades visuoperceptivas (discriminación, memoria visual, figura-fondo, integración visual…) y oculomotoras presentan unos valores más deteriorados en el grupo de estudiantes que presentan...

  17. Binocular Lens Treatment in Tree Shrews: Effect of Age and Comparison of Plus Lens Wear with Recovery from Minus Lens-induced Myopia

    OpenAIRE

    Siegwart, John T.; Norton, Thomas T.

    2010-01-01

    We examined normal emmetropization and the refractive responses to binocular plus or minus lenses in young (late infantile) and juvenile tree shrews. In addition, recovery from lens-induced myopia was compared with the response to a similar amount of myopia produced with plus lenses in age-matched juvenile animals. Normal emmetropization was examined with daily noncycloplegic autorefractor measures from 11 days after natural eye-opening (days of visual experience [VE]) when the eyes were in t...

  18. A Technique for Binocular Stereo Vision System Calibration by the Nonlinear Optimization and Calibration Points with Accurate Coordinates

    International Nuclear Information System (INIS)

    With the increasing need for higher accuracy measurement in computer vision, the precision of camera calibration is a more important factor. The objective of stereo camera calibration is to estimate the intrinsic and extrinsic parameters of each camera. We presented a high-accurate technique to calibrate binocular stereo vision system having been mounted the locations and attitudes, which was realized by combining nonlinear optimization method with accurate calibration points. The calibration points with accurate coordinates, were formed by an infrared LED moved with three-dimensional coordinate measurement machine, which can ensure indeterminacy of measurement is 1/30000. By using bilinear interpolation square-gray weighted centroid location algorithm, the imaging centers of the calibration points can be accurately determined. The accuracy of the calibration is measured in terms of the accuracy in the reconstructing calibration points through triangulation, the mean distance between reconstructing point and given calibration point is 0.039mm. The technique can satisfy the goals of measurement and camera accurate calibration

  19. A temperature inversion in WASP-33b? Large Binocular Telescope occultation data confirm significant thermal flux at short wavelengths

    CERN Document Server

    von Essen, C; Albrecht, S; Antoci, V; Smith, A M S; Dreizler, S; Strassmeier, K G

    2015-01-01

    We observed a secondary eclipse of WASP-33b quasi-simultaneously in the optical (~0.55 {\\mu}m) and the near-infrared (~1.05 {\\mu}m) using the 2x8.4 m Large Binocular Telescope. WASP-33 is a {\\delta} Scuti star pulsating with periods comparable to the eclipse duration, making the determination of the eclipse depth challenging. We use previously determined oscillation frequencies to model and remove the pulsation signal from the light curves, isolating the secondary eclipse. The determined eclipse depth is dF = 1.03 +/- 0.34 parts per thousand, corresponding to a brightness temperature of Tb = 3398 +/- 302 K. Combining previously published data with our new measurement we find the equilibrium temperature of WASP-33b to be Tb = 3358 +/- 165 K. We compare all existing eclipse data to a blackbody spectrum, to a carbon-rich non-inverted model and to a solar composition model with an inverted temperature structure. We find that current available data on WASP-33b's atmosphere can be best represented by a simple black...

  20. The Cepheid distance to the maser-host galaxy NGC 4258: Studying systematics with the Large Binocular Telescope

    CERN Document Server

    Fausnaugh, M M; Gerke, J R; Macri, L M; Riess, A G; Stanek, K Z

    2014-01-01

    We identify and phase a sample of 81 Cepheids in the maser-host galaxy NGC 4258 using the Large Binocular Telescope (LBT), and obtain calibrated mean magnitudes in up to 4 filters for a subset of 43 Cepheids using archival HST data. We employ 3 models to study the systematic effects of extinction, the assumed extinction law, and metallicity on the Cepheid distance to NGC 4258. We find a correction to the Cepheid colors consistent with a grayer extinction law in NGC 4258 compared to the Milky Way ($R_V =4.9$), although we believe this is indicative of other systematic effects. If we combine our Cepheid sample with previously known Cepheids, we find a significant metallicity adjustment to the distance modulus of $\\gamma_1 = -0.60 \\pm 0.21$ mag/dex, for the Zaritsky et al. (1994) metallicity scale, as well as a weak trend of Cepheid colors with metallicity. Conclusions about the absolute effect of metallicity on Cepheid mean magnitudes appear to be limited by the available data on the metallicity gradient in NGC...

  1. Simultaneous Water Vapor and Dry Air Optical Path Length Measurements and Compensation with the Large Binocular Telescope Interferometer

    CERN Document Server

    Defrère, D; Downey, E; Böhm, M; Danchi, W C; Durney, O; Ertel, S; Hill, J M; Hoffmann, W F; Mennesson, B; Millan-Gabet, R; Montoya, M; Pott, J -U; Skemer, A; Spalding, E; Stone, J; Vaz, A

    2016-01-01

    The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 $\\mu$m). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current performance of the system for dry air seeing compensation, we present simultaneous H-, K-, and N-band observations that illus...

  2. The adaptive secondary mirror for the Large Binocular Telescope: optical acceptance test and preliminary on-sky commissioning results

    Science.gov (United States)

    Riccardi, Armando; Xompero, Marco; Briguglio, Runa; Quirós-Pacheco, Fernando; Busoni, Lorenzo; Fini, Luca; Puglisi, Alfio; Esposito, Simone; Arcidiacono, Carmelo; Pinna, Enrico; Ranfagni, Piero; Salinari, Piero; Brusa, Guido; Demers, Richard; Biasi, Roberto; Gallieni, Daniele

    2010-07-01

    The Large Binocular Telescope (LBT) has two adaptive secondary mirrors based on 672 voice-coil force actuators. The shape of the mirror is controlled using internal metrology based on co-located capacitive sensors. The first mirror unit is currently mounted on LBT for on-sky commissioning as part of the First Light Adaptive Optics System (FLAO). During spring-time 2009 the optical acceptance test was performed using the 14-m optical test tower at the Osservatorio Astrofisico di Arcetri (INAF) showing the capability of flattening the shell at the level of 14nm rms residual surface error. This paper reports the optical layout, calibration procedures and results of the optical acceptance test. Moreover we report the first results obtained during the early runs of FLAO commissioning showing the ability of the mirror to compensate for atmospheric turbulence with extremely high Strehl ratio values (better than 80% in H-band) as permitted by the largest number of correcting degrees of freedom currently available on-sky for astronomical telescopes.

  3. Mathematics revealed

    CERN Document Server

    Berman, Elizabeth

    1979-01-01

    Mathematics Revealed focuses on the principles, processes, operations, and exercises in mathematics.The book first offers information on whole numbers, fractions, and decimals and percents. Discussions focus on measuring length, percent, decimals, numbers as products, addition and subtraction of fractions, mixed numbers and ratios, division of fractions, addition, subtraction, multiplication, and division. The text then examines positive and negative numbers and powers and computation. Topics include division and averages, multiplication, ratios, and measurements, scientific notation and estim

  4. Revealed Attention

    OpenAIRE

    Masatlioglu, Yusufcan; NAKAJIMA, Daisuke; Ozbay, Erkut Y

    2012-01-01

    The standard revealed preference argument relies on an implicit assumption that a decision maker considers all feasible alternatives. The marketing and psychology literatures, however, provide wellestablished evidence that consumers do not consider all brands in a given market before making a purchase (Limited Attention). In this paper, we illustrate how one can deduce both the decision maker's preference and the alternatives to which she pays attention and inattention from the observed behav...

  5. Revealed Attention

    OpenAIRE

    Yusufcan Masatlioglu; Daisuke Nakajima; Ozbay, Erkut Y

    2012-01-01

    The standard revealed preference argument relies on an implicit assumption that a decision maker considers all feasible alternatives. The marketing and psychology literatures, however, provide well-established evidence that consumers do not consider all brands in a given market before making a purchase (Limited Attention). In this paper, we illustrate how one can deduce both the decision maker's preference and the alternatives to which she pays attention and inattention from the observed beha...

  6. Obstacles to School Progression in Rural Pakistan: An Analysis of Gender and Sibling Rivalry Using Field Survey Data

    OpenAIRE

    Sawada, Yasuyuki; Lokshin, Michael

    2009-01-01

    This paper aims to identify the obstacles to school progression by using field surveys that were conducted in twenty-five Pakistani villages. The full-information maximum likelihood (FIML) estimation of the sequential schooling decision model reveals important dynamics of the gender difference in educational attainment, intrahousehold resource-allocation patterns, and transitory income and wealth effects. In the descriptive statistics as well as the econometric analyses, we find a high educat...

  7. "Obstacles to School Progression in Rural Pakistan: An Analysis of Gender and Sibling Rivalry Using Field Survey Data"

    OpenAIRE

    Yasuyuki Sawada; Michael Lokshin

    2007-01-01

    This paper aims to identify the obstacles to school progression by integrating field surveys conducted in twenty-five Pakistani villages, using economic theory and econometric analysis. The full-information maximum likelihood (FIML) estimation of the sequential schooling decision model reveals important dynamics of the gender difference in educational attainment, intrahousehold resource-allocation patterns, and transitory income and wealth effects. We find a high educational retention rate an...

  8. Embedded Binocular Stereo Vision Ranging System%嵌入式双目立体视觉测距系统

    Institute of Scientific and Technical Information of China (English)

    文成维; 陈文建; 詹泳

    2012-01-01

    设计和研究了一种基于S3C2440硬件平台和嵌入式Linux双目立体视觉测距系统.该系统通过使用两个USB摄像头同步采集图像数据,并利用OpenCV对采集的两幅图像的数据进行处理,计算目标物在两幅图像中的像素偏差,进而算出目标物到摄像头平面的距离,在论文中以车牌作为目标物.同时该系统用Qt/Embedded实现LED实时显示图像和数据.整个系统建立在嵌入式架构上,能独立完成图像采集,数据处理,实时显示等功能.只要改变定位算法,则能测出任意目标物的距离.%The paper designs and researches a binocular stereo measuring system based on S3C2440 hardware platform and embedded Linux. The system captures images data in synchronization by using 2 USB cameras, and then processes the images data in OpenCV Lib. Finally, calculate the pixel deviation of the target in two images, and then calculate the distance from the target to camera plane, license plate be seen as the target in the paper. At the same time, the system displays the images and dates on LED with Qt/Embedded GUI in real time. The whole system is built on an embedded architecture, able to capture images and process data and real-time display data independently. When change location algorithm, we can calculate the distance of any targets.

  9. Screening for retinopathy of prematurity-a comparison between binocular indirect ophthalmoscopy and RetCam 120

    Directory of Open Access Journals (Sweden)

    Shah Parag

    2006-01-01

    Full Text Available Aim: To compare the photographic screening for retinopathy of prematurity (ROP using RetCam 120 with binocular indirect ophthalmoscope (BIO, which is the current gold standard. Setting and Design: Prospective, comparative study. Materials and Methods: A total of 87 RetCam examinations were performed on 27 premature babies. They were stored in a separate file after deleting the identifying information. At the same visit using the BIO with scleral depression, an experienced vitreoretinal surgeon evaluated the fundus in detail. A masked examiner then evaluated the RetCam photographs for presence or absence of ROP, the stage and zone of the disease, and the presence or absence of plus disease. These data were then compared with the BIO findings to determine the sensitivity, specificity, and the positive and negative predictive values of the method. Results: ROP was detected in 63 of 87 examinations by BIO and in 56 of 87 RetCam examinations. Nine RetCam examinations were false-negative and two were false-positive. Sensitivity of RetCam was 85.71% (54/63 and specificity was 91.66% (22/24. The positive and negative predictive values were 96.43% and 70.97% respectively. Conclusion: Nine cases having ROP were missed by the RetCam. All these cases were either in zone 3 or the outer part of zone 2, which later regressed. These were missed mostly because of the restricted mobility of the camera head caused by its size and the barrier caused by the lid speculum arms. No case of threshold ROP was missed. RetCam may replace BIO for screening of ROP.

  10. Large Binocular Telescope/LUCIFER spectroscopy: kinematics of a compact early-type galaxy at z ≃ 1.4

    Science.gov (United States)

    Longhetti, M.; Saracco, P.; Gargiulo, A.; Tamburri, S.; Lonoce, I.

    2014-04-01

    We present a high signal-to-noise ratio (S/N > 10) medium-resolution (R = 2000) Large Binocular Telescope/LUCIFER spectrum of the early-type galaxy (ETG) S2F1-142 at z ≃ 1.4. By means of the CaT line at 8662 Å, we measured its redshift z = 1.386 ± 0.001 and we estimated its velocity dispersion σ v=340^{-60}_{+120} km s-1. Its corresponding virial mass is 3.9 × 1011 M⊙, compatible with the stellar mass estimates obtained assuming initial mass functions (IMFs) less dwarf rich than the Salpeter one. S2F1-142 is a compact galaxy with Re = 3.1 ± 0.2 kpc, i.e. an effective radius more than three times smaller than the average Re of ETGs with the same mass in the local Universe. At the same time, we found local and high-redshift galaxies with a similar mass content and similar effective radius confirming that it is fully consistent with the already available measures of Re and σv both in the local and in the distant Universe. Considering the distribution of Re and σv as a function of the stellar mass content of ETGs, both in the local and in the distant Universe, we noticed that the measured velocity dispersions of the more compact galaxies are on average slightly lower than expected on the basis of their compactness and the virial theorem, suggesting that (i) their dark matter content is lower than in the more diffuse galaxies and/or (ii) their luminosity profiles are steeper than in the more diffuse galaxies and/or (iii) their larger compactness is an apparent effect caused by the overestimate of their stellar mass content (due to bottom lighter IMF and/or systematic affecting the stellar mass estimates).

  11. 3D-MAD: A Full Reference Stereoscopic Image Quality Estimator Based on Binocular Lightness and Contrast Perception.

    Science.gov (United States)

    Zhang, Yi; Chandler, Damon M

    2015-11-01

    Algorithms for a stereoscopic image quality assessment (IQA) aim to estimate the qualities of 3D images in a manner that agrees with human judgments. The modern stereoscopic IQA algorithms often apply 2D IQA algorithms on stereoscopic views, disparity maps, and/or cyclopean images, to yield an overall quality estimate based on the properties of the human visual system. This paper presents an extension of our previous 2D most apparent distortion (MAD) algorithm to a 3D version (3D-MAD) to evaluate 3D image quality. The 3D-MAD operates via two main stages, which estimate perceived quality degradation due to 1) distortion of the monocular views and 2) distortion of the cyclopean view. In the first stage, the conventional MAD algorithm is applied on the two monocular views, and then the combined binocular quality is estimated via a weighted sum of the two estimates, where the weights are determined based on a block-based contrast measure. In the second stage, intermediate maps corresponding to the lightness distance and the pixel-based contrast are generated based on a multipathway contrast gain-control model. Then, the cyclopean view quality is estimated by measuring the statistical-difference-based features obtained from the reference stereopair and the distorted stereopair, respectively. Finally, the estimates obtained from the two stages are combined to yield an overall quality score of the stereoscopic image. Tests on various 3D image quality databases demonstrate that our algorithm significantly improves upon many other state-of-the-art 2D/3D IQA algorithms. PMID:26186775

  12. Revealing Rembrandt

    Directory of Open Access Journals (Sweden)

    Andrew J Parker

    2014-04-01

    Full Text Available The power and significance of artwork in shaping human cognition is self-evident. The starting point for our empirical investigations is the view that the task of neuroscience is to integrate itself with other forms of knowledge, rather than to seek to supplant them. In our recent work, we examined a particular aspect of the appreciation of artwork using present-day functional magnetic resonance imaging (fMRI. Our results emphasised the continuity between viewing artwork and other human cognitive activities. We also showed that appreciation of a particular aspect of artwork, namely authenticity, depends upon the co-ordinated activity between the brain regions involved in multiple decision making and those responsible for processing visual information. The findings about brain function probably have no specific consequences for understanding how people respond to the art of Rembrandt in comparison with their response to other artworks. However, the use of images of Rembrandt’s portraits, his most intimate and personal works, clearly had a significant impact upon our viewers, even though they have been spatially confined to the interior of an MRI scanner at the time of viewing. Neuroscientific studies of humans viewing artwork have the capacity to reveal the diversity of human cognitive responses that may be induced by external advice or context as people view artwork in a variety of frameworks and settings.

  13. Imaging with LINC-NIRVANA, the Fizeau interferometer of the Large Binocular Telescope: state of the art and open problems

    International Nuclear Information System (INIS)

    LINC-NIRVANA (LN) is the Fizeau interferometer of the Large Binocular Telescope which consists of two 8.4 m mirrors with a center-to-center distance of 14.4 m, hence providing a maximum path of 22.8 m in the direction of the baseline joining the two centers. LN is a true imager since interference occurs in the focal plane and not in the aperture plane as with essentially all the existing interferometers. However, an LN image is characterized by an anisotropic resolution: that of a 22.8 m mirror in the direction of the baseline and that of a 8.4 m mirror in the orthogonal direction. In order to obtain a unique image with a high and isotropic resolution, several images must be detected with different orientations of the baseline and suitably processed. Therefore, the instrument will routinely require the use of image reconstruction methods for providing astronomical images with unprecedented resolution, in principle ten times the resolution of the Hubble Space Telescope. This review concerns the image reconstruction problem for LN and is based essentially on our work. After a description of the main features of the telescope and of the interferometer, it contains a discussion of the problem and of the approximations introduced in its formulation. In short, it is reduced to multiple-image deconvolution with Poisson data. Similarity with the image reconstruction problem in emission tomography is stressed and utilized for introducing suitable iterative reconstruction methods. These methods are extended to regularized versions of the problem. Efficiency is another important issue because the size of LN images is of the order of 4.2 megapixels; therefore, acceleration methods are also discussed. All methods are tested on synthetic images because, even if the instrument is in an advanced stage of realization, it will be presumably operative in 2014. The algorithms of the proposed image reconstruction methods are implemented in the Software Package AIRY (astronomical image

  14. Amblyopia and Binocular Vision

    OpenAIRE

    Birch, Eileen E.

    2012-01-01

    Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3% to 3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of bin...

  15. Driving with binocular visual field loss? A study on a supervised on-road parcours with simultaneous eye and head tracking.

    Directory of Open Access Journals (Sweden)

    Enkelejda Kasneci

    Full Text Available Post-chiasmal visual pathway lesions and glaucomatous optic neuropathy cause binocular visual field defects (VFDs that may critically interfere with quality of life and driving licensure. The aims of this study were (i to assess the on-road driving performance of patients suffering from binocular visual field loss using a dual-brake vehicle, and (ii to investigate the related compensatory mechanisms. A driving instructor, blinded to the participants' diagnosis, rated the driving performance (passed/failed of ten patients with homonymous visual field defects (HP, including four patients with right (HR and six patients with left homonymous visual field defects (HL, ten glaucoma patients (GP, and twenty age and gender-related ophthalmologically healthy control subjects (C during a 40-minute driving task on a pre-specified public on-road parcours. In order to investigate the subjects' visual exploration ability, eye movements were recorded by means of a mobile eye tracker. Two additional cameras were used to monitor the driving scene and record head and shoulder movements. Thus this study is novel as a quantitative assessment of eye movements and an additional evaluation of head and shoulder was performed. Six out of ten HP and four out of ten GP were rated as fit to drive by the driving instructor, despite their binocular visual field loss. Three out of 20 control subjects failed the on-road assessment. The extent of the visual field defect was of minor importance with regard to the driving performance. The site of the homonymous visual field defect (HVFD critically interfered with the driving ability: all failed HP subjects suffered from left homonymous visual field loss (HL due to right hemispheric lesions. Patients who failed the driving assessment had mainly difficulties with lane keeping and gap judgment ability. Patients who passed the test displayed different exploration patterns than those who failed. Patients who passed focused longer on

  16. Pakistan: Regional rivalries, local impacts

    OpenAIRE

    Sheikh, Mona Kanwal; Shaikh, Farzana; Price, Gareth

    2012-01-01

    What connects Chinas to the challenges of separatism in Balochistan? Why is India important when it comes to water shortages in Pakistan? How does jihadism in Punjab an Sindh differ from religious militancy in the Federally Administered Tribal Areas (FATA)? Why do Iran and Saudi Arabia matter for the challenges faced by Pakistan in Gilgit-Baltistan? These are some of the questions that are raised and discussed in the analytical contribution of this report. Overall, the present report aims to ...

  17. An investigation on binocular summation response of visual evoked potential in children with hyperopia amblyopia%弱视儿童双眼总和视觉诱发电位变化的研究

    Institute of Scientific and Technical Information of China (English)

    于春红; 廖瑜俊; 杨洋; 邓燕; 彭小维; 鄢涛; 殷小龙

    2009-01-01

    Objective Conventional examination for vision function adopts subjective psychophysics methods.Pattern visual evoked potential (P-VEP) binocular summation response is a new objective way for the test of vision function.But its clinical value in evaluating vision function of amblyopia children is still in controversy.This study was to explore the binocular vision and the feature of P-VEP binocular summation in children with amblyopia and evaluate the significance of P-VEP binocular summation in binocular vision.MethodsThis is a case-controlled study.P-VEP binocular summation response and single ocular P-VEP response was respectively recorded in 151 hyperopia amblyopia children and 80 age- and gender-matched normal children.P-VEP response from children with hyperopia amblyopia was recorded under the corrected vision.The hyperopia amblyopia was diagnosed based on the standard of National Children Amblyopia and Strabismus Prevention and Treatment Working Group.The feature of P-VEP binocular summation was further analyzed and compared with monocular VEP response.Informed consent was obtained from each subject or custodian prior to the trail.ResultsNo significant difference was found in latency between P-VEP binocular summation response and monocular P-VEP response whether amblyopia children or normal children(P>0.05).Binocular response/monocular response value in amblyopia children was lower than that in normal children(P<0.05).Binocular response/monocular response value in mild or moderate amblyopia children was higher than that in severe amblyopia children(P<0.05).Binocular response/monocular response value was significantly reduced in the children with binocular vision than in the children without binocular vision (P<0.05).ConclusionP-VEP binocular vision,acting as an evaluation factor,could impartially reflect the function of binocular vision of amblyopia children.%目的 探讨弱视儿童双眼视功能及总和图形视觉诱发电位(P-VEP)反应的特

  18. 基于投影直方图匹配的双目视觉跟踪算法%Binocular object tracking method using projection histogram matching

    Institute of Scientific and Technical Information of China (English)

    王杰; 蒋明敏; 花晓慧; 鲁守银; 李金屏

    2015-01-01

    An effective object location and tracking method is proposed for a robot manipulator's binocular visual servo system by utilizing projection histogram matching and the epipolar geometric constraint. The object is selected manually in the two vision systems, then the horizontal and vertical projection histograms, in multiple color spaces of the selected object, are extracted as matching templates for these two vision systems. The object in one vision system can be tracked by making use of the principle of moving continuity and the matching templates of the projec-tion histograms in multiple color spaces. In the other vision system, the object is located roughly based on epipolar geometric constraint, and then it can be tracked accurately using the same method which is used in the first vision. The proposed method describes the object's structural information by using horizontal and vertical projection histo-grams, and realizes the function of object tracking and registration in the binocular visual system, which is helpful in the precise location and visual measurement of the tracked object. The experiment results indicate that this meth-od can realize the binocular object tracking with high efficiency and strong robustness.%为了在机器人机械手双目视觉伺服系统中跟踪并精确定位目标的空间位置,提出了一种利用投影直方图匹配和极线几何约束的目标跟踪方法. 分别在2个视觉中人工标定目标,并提取目标在多颜色空间的水平、垂直投影直方图作为匹配模板;在一个视觉中利用目标的运动一致性原则和投影直方图匹配搜索并跟踪目标;在另一个视觉中依据双目视觉系统的极线几何原理限定目标搜索范围,搜索并定位目标. 该方法利用水平、垂直投影直方图描述目标的结构信息,同时完成了双目视觉系统中的目标跟踪与配准功能,有利于目标的精确定位和视觉测量. 实验结果表明,该方法可在双目视

  19. Autonomous Mapping for Robot Using a Combination of Binocular Stereo Vision and GSOM Algorithm%双目立体视觉和GSOM相结合的机器自主地图构建方法

    Institute of Scientific and Technical Information of China (English)

    于乃功; 王丽

    2011-01-01

    双目立体视觉和自组织可增长特征映射图GSOM (Growing Self-organizing Map)相结合的机器人地图构建方法首先利用双目立体摄像机采集图像,借助双目立体视觉处理技术,将采集到的图像信息转化成神经网络的训练样本;然后利用GSOM的地图绘制算法,通过不断增加新的神经元实现网络规模的增长,用441个SOM神经元便表示了2000个样本点的环境特征信息的拓扑地图,体现了对输入样本分布的逼近特性;实验结果表明双目立体视觉和GSOM相结合的机器人自主地图构建方法可行,并表现出类似生物的自主智能行为.%Autonomous mapping for robot using a combination of binocular stereo vision and GSOM (Growing Self-organizing Map) Algorithm collects images using a binocular stereo camera. After treatment of binocular stereo vision technology, image information generates neural network training samples. Appling GSOM algorithm by continuously increasing new neurons in the growth of network scale, the algorithm uses 441 SOM neurons generate a topologic map which describes 2000 sample' s environmental information and reflects the approximation characteristics of input data distribution. Through testing GSOM mapping algorithm, the experimental results show that autonomous mapping for robot using a combination of binocular stereo vision and GSOM algorithm is feasible; and the system shows similar biological behaviours of autonomous intelligence.

  20. 基于双目视觉的机器人自定位方法研究%Robot autonmouls localization method study based on binocular vision

    Institute of Scientific and Technical Information of China (English)

    张华; 夏菠

    2015-01-01

    研究了一种利用双目立体视觉的机器人自定位方法。首先提取双目图像序列的 Harris 角点特征,并计算其水平与垂直方向上的 Sobel 响应,基于此响应,采用绝对误差累计的最小窗口查找(SAD)原理进行立体匹配。将改进的 RANSAC 算法用于特征匹配点优化中,利用高斯牛顿迭代法求解机器人位姿,实现了机器人的自定位。室内、外实验,及与 BoofCV 视觉库中的立体视觉定位算法的对比分析,证明该方法在运算速度、定位精度和稳定性等方面均能满足实际应用需求。%A robot autonomous localization method based on binocular vision image sequences was studied.Harris corner features were extracted with the binocular vision image sequence and Sobel fil-ter responses of horizontal and vertical was simply compared to each other by using sum of absolute differences error metric,and matching feature points based on the responses value.The improved RANSAC algorithm was used for feature matching optimization.Finally the gauss-newton iterative method was used for solving over determined nonlinear equations of robot pose estimation,and the o-rientation of the robot was realized.Through indoor and outdoor scene experiments,as well as com-paring with the stereo visual odometry algorithm in BoofCV visual library,experiments show that the proposed approach can meet the application requirements in terms of accuracy,stability and run-time.

  1. 基于双目视觉的机器人自定位方法研究%Robot autonmouls localization method study based on binocular vision

    Institute of Scientific and Technical Information of China (English)

    张华; 夏菠

    2015-01-01

    A robot autonomous localization method based on binocular vision image sequences was studied.Harris corner features were extracted with the binocular vision image sequence and Sobel fil-ter responses of horizontal and vertical was simply compared to each other by using sum of absolute differences error metric,and matching feature points based on the responses value.The improved RANSAC algorithm was used for feature matching optimization.Finally the gauss-newton iterative method was used for solving over determined nonlinear equations of robot pose estimation,and the o-rientation of the robot was realized.Through indoor and outdoor scene experiments,as well as com-paring with the stereo visual odometry algorithm in BoofCV visual library,experiments show that the proposed approach can meet the application requirements in terms of accuracy,stability and run-time.%研究了一种利用双目立体视觉的机器人自定位方法。首先提取双目图像序列的 Harris 角点特征,并计算其水平与垂直方向上的 Sobel 响应,基于此响应,采用绝对误差累计的最小窗口查找(SAD)原理进行立体匹配。将改进的 RANSAC 算法用于特征匹配点优化中,利用高斯牛顿迭代法求解机器人位姿,实现了机器人的自定位。室内、外实验,及与 BoofCV 视觉库中的立体视觉定位算法的对比分析,证明该方法在运算速度、定位精度和稳定性等方面均能满足实际应用需求。

  2. Large Binocular Telescope and Sptizer Spectroscopy of Star-forming Galaxies at 1 < z < 3: Extinction and Star Formation Rate Indicators

    Science.gov (United States)

    Rujopakarn, W.; Rieke, G. H.; Papovich, C. J.; Weiner, B. J.; Rigby, Jane; Rex, M.; Bian, F.; Kuhn, O. P.; Thompson, D.

    2012-01-01

    We present spectroscopic observations in the rest-frame optical and near- to mid-infrared wavelengths of four gravitationally lensed infrared (IR) luminous star-forming galaxies at redshift 1 LUCIFER instrument on the Large Binocular Telescope and the Infrared Spectrograph on Spitzer. The sample was selected to represent pure, actively star-forming systems, absent of active galactic nuclei. The large lensing magnifications result in high signal-to-noise spectra that can probe faint IR recombination lines, including Paa and Bra at high redshifts. The sample was augmented by three lensed galaxies with similar suites of unpublished data and observations from the literature, resulting in the final sample of seven galaxies. We use the IR recombination lines in conjunction with Ha observations to probe the extinction, Av, of these systems, as well as testing star formation rate (SFR) indicators against the SFR measured by fitting spectral energy distributions to far-IR photometry. Our galaxies occupy a range of Av from 0 to 5.9 mag, larger than previously known for a similar range of IR luminosities at these redshifts. Thus, estimates of SFR even at z 2 must take careful count of extinction in the most IR luminous galaxies.We also measure extinction by comparing SFR estimates from optical emission lines with those from far- IR measurements. The comparison of results from these two independent methods indicates a large variety of dust distribution scenarios at 1 < z < 3. Without correcting for dust extinction, the Ha SFR indicator underestimates the SFR; the size of the necessary correction depends on the IR luminosity and dust distribution scenario. Individual SFR estimates based on the 6.2µm polycyclic aromatic hydrocarbon emission line luminosity do not show a systematic discrepancy with extinction, although a considerable, 0.2 dex, scatter is observed.

  3. 双目视觉的台球桌面的三维重构%3D Reconstruction of Desktop of Table Tennis Based on the Binocular Vision

    Institute of Scientific and Technical Information of China (English)

    张旭飞; 王朝立; 袁伟

    2013-01-01

    At present, with the rapid development of the computer technologies which has grown dramatically, and there are more and more sports competition where some high and new technologies are emploited as the electronic referee to assist referee to do the decisions, in order to achieve the spirit of fair play which respected by Olympic. During this process, the camera plays an important role in computer vision. 3D reconstruction is a process based on a single view or multi-view images to obtain the 3D information in the field of computer vision. In this paper, in order to complete a task about three-dimensional reconstruction of desktop of Table tennis, we take 3D reconstruction technologies in computer vision as the mainly research object, including specific details about the theoretical knowledge on the binocular vision and the reconstruction algorithm provided by the computer vision library OpenCV. The 3D reconstruction of billiards desktop have strong practical significance, which laid a good foundation for the electronic referee to work in the billiards competition.%  随着计算机技术的迅猛发展,在越来越多的体育比赛中纷纷出现了电子裁判来辅助裁判进行判罚工作,以实现奥林匹克的公平竞赛精神。而在实现这种数字化裁判的过程中,摄像机在计算机视觉中起着重要的作用,三维重构就是根据单视图或者多视图的图像重建三维信息的过程。主要以计算机视觉中的三维重构技术作为研究对象,具体详述了有关双目视觉的一些理论知识,充分利用计算机视觉库OpenCV提供的重建算法,来完成对台球桌面的三维重构工作。台球桌面的三维重构具有很强的现实意义,为电子裁判进入桌球比赛打下了良好的基础。

  4. 3D Reconstruction of Desktop of Table Tennis Based on the Binocular Vision%双目视觉的台球桌面的三维重构

    Institute of Scientific and Technical Information of China (English)

    张旭飞; 王朝立; 袁伟

    2013-01-01

    At present, with the rapid development of the computer technologies which has grown dramatically, and there are more and more sports competition where some high and new technologies are emploited as the electronic referee to assist referee to do the decisions, in order to achieve the spirit of fair play which respected by Olympic. During this process, the camera plays an important role in computer vision. 3D reconstruction is a process based on a single view or multi-view images to obtain the 3D information in the field of computer vision. In this paper, in order to complete a task about three-dimensional reconstruction of desktop of Table tennis, we take 3D reconstruction technologies in computer vision as the mainly research object, including specific details about the theoretical knowledge on the binocular vision and the reconstruction algorithm provided by the computer vision library OpenCV. The 3D reconstruction of billiards desktop have strong practical significance, which laid a good foundation for the electronic referee to work in the billiards competition.%  随着计算机技术的迅猛发展,在越来越多的体育比赛中纷纷出现了电子裁判来辅助裁判进行判罚工作,以实现奥林匹克的公平竞赛精神。而在实现这种数字化裁判的过程中,摄像机在计算机视觉中起着重要的作用,三维重构就是根据单视图或者多视图的图像重建三维信息的过程。主要以计算机视觉中的三维重构技术作为研究对象,具体详述了有关双目视觉的一些理论知识,充分利用计算机视觉库OpenCV提供的重建算法,来完成对台球桌面的三维重构工作。台球桌面的三维重构具有很强的现实意义,为电子裁判进入桌球比赛打下了良好的基础。

  5. Large Binocular Telescope and Spitzer Spectroscopy of Star-forming Galaxies at 1

    Science.gov (United States)

    Rujopakarn, W.; Rieke, G. H.; Papovich, C. J.; Weiner, B. J.; Rigby, J. R.; Rex, M.; Bian, F.; Kuhn, O. P.; Thompson, D.

    2012-08-01

    We present spectroscopic observations in the rest-frame optical and near- to mid-infrared wavelengths of four gravitationally lensed infrared (IR) luminous star-forming galaxies at redshift 1 LUCIFER instrument on the Large Binocular Telescope and the Infrared Spectrograph on Spitzer. The sample was selected to represent pure, actively star-forming systems, absent of active galactic nuclei. The large lensing magnifications result in high signal-to-noise spectra that can probe faint IR recombination lines, including Paα and Brα at high redshifts. The sample was augmented by three lensed galaxies with similar suites of unpublished data and observations from the literature, resulting in the final sample of seven galaxies. We use the IR recombination lines in conjunction with Hα observations to probe the extinction, Av , of these systems, as well as testing star formation rate (SFR) indicators against the SFR measured by fitting spectral energy distributions to far-IR photometry. Our galaxies occupy a range of Av from ~0 to 5.9 mag, larger than previously known for a similar range of IR luminosities at these redshifts. Thus, estimates of SFR even at z ~ 2 must take careful count of extinction in the most IR luminous galaxies. We also measure extinction by comparing SFR estimates from optical emission lines with those from far-IR measurements. The comparison of results from these two independent methods indicates a large variety of dust distribution scenarios at 1 < z < 3. Without correcting for dust extinction, the Hα SFR indicator underestimates the SFR; the size of the necessary correction depends on the IR luminosity and dust distribution scenario. Individual SFR estimates based on the 6.2 μm polycyclic aromatic hydrocarbon emission line luminosity do not show a systematic discrepancy with extinction, although a considerable, ~ 0.2 dex, scatter is observed. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT

  6. Dynamic Obstacle Avoidance Based on Binocular Vision for AS-R Mobile Robots%AS-R 移动机器人基于双目视觉的动态避障

    Institute of Scientific and Technical Information of China (English)

    张寒; 张冰蔚

    2016-01-01

    针对移动机器人的动态避障问题,以AS-R移动机器人为平台,设计了一种基于双目视觉的动态避障方法。从双目视觉系统出发,介绍了AS-R机器人的视觉系统,研究了AS-R机器人的运动原理,探讨了图像信息处理的过程;最后设计了两种简单环境下机器人的动态避障,并验证了所提方法的有效性。%Aiming at the problem of obstacle avoidance for mobile robot ,with the platform of AS-R mobile robot ,a novel approach based on binocular vision for dynamic obstacle avoidance was put forward .Starting from binocular vision system ,the paper intro-duced the AS-R robot vision system ,studied the principles of AS-R robot movement ,and discussed the processing of image informa-tion .Experiments based on both simulation platform and ASR robot verified the effectiveness of the proposed approach .

  7. Resultados do implante bilateral de lente intra-ocular multifocal SA-40N no Hospital de Olhos de Minas Gerais Visual outcome with binocular implantation of SA-40N multifocal intraocular lens at "Hospital de Olhos de Minas Gerais"

    Directory of Open Access Journals (Sweden)

    Cristina Moreira Salera

    2005-02-01

    Full Text Available OBJETIVOS: Avaliar os resultados da facoemulsificação com implante bilateral da lente intra-ocular multifocal modelo SA-40N no Hospital de Olhos de Minas Gerais. MÉTODOS: Foram analisados retrospectivamente os prontuários de 58 pacientes (116 olhos submetidos à cirurgia de facoemulsificação com implante binocular de lente intra-ocular multifocal modelo SA-40N. RESULTADOS: O equivalente esférico médio pré-operatório foi +1,55 dioptrias (variando de -4,25 a +6,25 D e no pós-operatório foi -0,59 dioptrias (variando de -2,25 a +1,25 D. No trigésimo dia de pós-operatório 94 olhos (81% apresentavam visão para longe igual a 20/20 com correção. Para a visão de perto binocular 29 (50% pacientes eram capazes de ler J1 sem correção e 25 pacientes (43,1%, J2 sem correção. Comparando-se as acuidades visuais com correção (AVCC antes e após a cirurgia observamos que em 68 olhos (58,6% a AVCC foi mantida, em 33 olhos (28,4% houve ganho de linhas de visão e em 15 olhos (12,9% houve perda de linhas de visão. Quanto às complicações 19 pacientes (32,7% queixavam-se de halos, em três olhos (2,6% ocorreu edema macular cistóide e em cinco olhos (4,3% ocorreu opacificação de cápsula posterior. Em 36 pacientes (62,1% não foi necessária a prescrição de óculos no pós-operatório. CONCLUSÃO: Os resultados deste estudo indicam que a lente intra-ocular multifocal promove redução na dependência do uso dos óculos e grande satisfação do paciente apesar da ocorrência de halos.PURPOSE: To evaluate the outcomes of phacoemulsification with binocular implantation of SA-40N multifocal intraocular lens at the "Hospital de Olhos de Minas Gerais". METHODS: The charts of 58 patients (116 eyes who were submitted to phacoemulsification with binocular implantation of SA-40N multifocal intraocular lens were retrospectively analyzed. RESULTS: The mean preoperative spherical equivalent was +1.55D (ranging from -4.25 to +6.25D and after surgery

  8. Large Binocular Telescope - Teilprojekt Lucifer

    OpenAIRE

    Jäger, Klaus; Mandel, Holger

    2010-01-01

    An Lucifer arbeiten die Mannheimer Fachhochschule für Technik und Gestaltung und die Landessternwarte Heidelberg eng zusammen. Das Projekt ist der deutsche Beitrag für ein neues Riesenteleskop in Arizona, USA. Es handelt sich um einen Spektrographen für den nahen Infrarotbereich, der auch als Kamera genutzt werden kann. Seine Besonderheit: Er kann das ferne Weltall erforschen, denn dort haben sich durch den Urknall viele uralte Spektren im Infrarotbereich ergeben, denen Lucifer auf die Spur k...

  9. Viewing the Constellations with Binoculars

    CERN Document Server

    Kambic, Bojan

    2010-01-01

    A guide to practical astronomy. It introduces the reader to some basic (and some not-so-basic) astronomical concepts, and discusses the stars and their evolution, the planets, nebulae, and distant galaxies

  10. Negative “gossip” stimuli modulate left-lateralized P1 component while viewing neutral faces

    DEFF Research Database (Denmark)

    Weed, Ethan; Allen, Micah Galen; Gramm, Daniel

    Language allows us to operate more efficiently in the world. By hearing about others’ experiences, we are able to orient toward things that could be beneficial to us, and avoid hazards. This sharing of experiences is particularly prominent in the social realm. Using a binocular rivalry paradigm......, Anderson et al. (2011) showed that short “gossip” phrases modulated the length of time faces remained perceptually dominant. However, binocular rivalry is measured by self-report. We used EEG to investigate the timing of gossip’s early effect on face perception. Gossip stimuli were those used by Anderson...

  11. 基于OpenCV的双目立体视觉监控跟踪系统%A Binocular Stereo Vision Surveillance Tracking System which Based on Computer Vision Library OpenCV

    Institute of Scientific and Technical Information of China (English)

    万智萍; 叶仕通

    2013-01-01

    Monitoring equipment of the present stage cannot independently obtain the distance information of the target region, and when it is at outside of a certain range, which due to a deeper level of image blur can not identify a specific individual.For the above problems, designing and development of a binocular stereo vision surveillance tracking system which based on computer vision library OpenCV, and combined with self-developed to binocular stereovision ranging Improvement Act and contour search method, which distance measurements and contour recognition can be achieved on the objects within the monitored region.Experimental results show that based binocular stereo vision OpenCV monitoring tracking system is reliable and stable, within a certain range which can to achieve the experimental requirements.%现阶段的监控设备无法自主获取目标区域的距离信息,而且在一定范围之外,由于图像模糊程度加深而无法对特定个体进行识别确认.针对以上存在的问题,设计并开发了基于计算机视觉库OpenCV(IntelOpen Source Computer Vision Library)的双目立体视觉监控跟踪系统.利用OpenCV强大的计算机视觉和图像处理能力,结合自行研究的双目立体视觉测距改进法和轮廓搜索法,能实现对监控区域内的物体进行距离测量和轮廓识别.通过实验结果表明,基于OpenCV的双目立体视觉监控跟踪系统运行可靠稳定,在一定范围内达到了实验要求.

  12. Predicting the conscious experience of other people

    DEFF Research Database (Denmark)

    Sandberg, Kristian; Bahrami, Bahador; Kanai, Ryota;

    consciousness, and to test whether such correlates generalized reliably across individuals. We used a 274 channel MEG system to record signals from 8 healthy participants while they viewed an intermittently presented binocular rivalry stimulus consisting of a face and a grating. Using a leave-one-out cross......-validation procedure, we trained support vector machines on the MEG signals to decode the rivalry percept. Decoding was significantly better than chance in all participants. We then tested whether a support vector machine trained on MEG signals from one participant could successfully decode the rivalry percept of...

  13. Proverbs Reveal Culture Diversity

    OpenAIRE

    Hou, Rong

    2013-01-01

    Through the analysis of property of culture and proverb, it can be known that proverb can help one to understand a culture. The way proverb reveals culture diversity can be connected with the patterns of value dimension, which conveys the information of a culture’s deep meaning. From the perspective of uncertainty-avoidance, it can be seen that although Ireland and America both are low-uncertainty-avoidance cultures, they mainly have different life attitudes, because that Americans put more e...

  14. 基于MATLAB与OpenCV相结合的双目立体视觉测距系统%Binocular stereo vision distance measurement system based on a combination of Matlab and OpenCV

    Institute of Scientific and Technical Information of China (English)

    汪珍珍; 赵连玉; 刘振忠

    2013-01-01

    Binocular stereo vision distance measuring technology is a hot research topic in the field of machine vision. This paper focuses on a binocular stereo vision distance measurement system based on a combination of MATLAB and OpenCV, U-sing MATLAB camera calibration, and then import the results to OpenCV for subsequent image processing and stereo matching. Camera calibration via MATLAB Calibration Toolbox has better robustness and higher precision than in the artificial calibration and OpenCV calibration. The stereo matching adopt the SAD match which is a relatively rapid and real-time regional match and able to be better applied to actual projects.%双目立体视觉测距技术是当前机器视觉领域中的一个主要研究内容.本文设计了基于MATLABatlab与OpenCV相结合的双目立体视觉测距系统,利用MATLAB进行摄像机标定后将结果导入到OpenCV进行后续的图像处理与立体匹配.摄像机标定通过MATLAB标定工具箱来完成,较于人工标定和OpenCV标定具有更好的鲁棒性和较高的精确性.立体匹配采用区域匹配中相对快速实时的SAD匹配,能够更好的被应用于工程实际.

  15. 基于双目立体视觉的西瓜子三维形态检测%Detection of Watermelon Seed Three-dimensional Shape Based on Binocular Stereo Vision

    Institute of Scientific and Technical Information of China (English)

    王士鑫; 孙涌; 余建飞; 张刚

    2012-01-01

    To improve the watermelon seed automated screening system performance, this paper presents a method of watermelon seed combination parallel binocular stereo vision and bone line to use in measurement and process the warping degree of watermeldn seed. This method uses binocular stereo vision technique for the reconstruction of three-dimensional object's surface information. The three-dimensional information is projected in space rectangular coordinates, it can obtain the seed profile in the front view and side view. The combination of Curvature Scale Space(CSS) and bone line is used in feature extraction of the side view profile of the watermelon seed. Experimental results show that the method has high recognition accuracy for warped seed.%为提高西瓜子自动筛选系统的性能,提出一种用于度量和处理西瓜子弯翘度的方法.把双目平行立体视觉与骨骼线相结合,利用双目立体视觉技术重建物体表面的三维信息.将该信息进行正交投影,分别得到西瓜子在前视图和侧视图的轮廓.利用曲率尺度空间与骨骼线相结合的方法对侧视图的瓜子轮廓进行特征提取.实验结果表明,该方法对弯翘瓜子有较高的识别精度.

  16. Organizational Design and the Intensity of Rivalry

    OpenAIRE

    Govert Vroom

    2006-01-01

    We analyze the effect of managerial compensation schemes and organizational structure on competitive behavior in imperfectly competitive product markets. Previous research suggests that in cases of strategic substitutability, firms tend to choose organizational structures and compensation systems that commit the firm to behaving aggressively in the product market, reducing firm and industry profits. In contrast, we show that while compensation and structure in isolation lead to excessive aggr...

  17. The Trifid Nebula: Stellar Sibling Rivalry

    Science.gov (United States)

    2001-01-01

    A zoom into the Trifid Nebula starts with ground-based observations and ends with a Hubble Space Telescope (HST) image. Another HST image shows star formation in the nebula and the video concludes with a ground-based image of the Trifid Nebula.

  18. Sibling Rivalry: A Six Country Comparison

    OpenAIRE

    Wolter, Stefan C.

    2003-01-01

    In this paper we analyse with the PISA data on literacy achievement of fifteen-year-old pupils in six member countries of the OECD, whether the fact of having many siblings affects the individual educational outcome. The hypothesis that we test is whether parents? resources matter for educational outcome. If they do and parents are constraint in their budgets, siblings will rival for the limited parental resources and thereby negatively affect educational outcome. The hypothesis is tested by ...

  19. Private Labels, Price Rivalry, and Public Policy

    OpenAIRE

    Gabrielsen, Tommy Staahl; Sørgard, Lars

    2000-01-01

    The article examines how the existence of a retailer owned brand, private label, aspects the price setting of a national brand. We …nd that the potential for a private label introduction may lead to price concessions from the national brand producer, but that actual private label introduction as such may very well lead to higher retail prices on national brands. We argue that this may have important implications for the interpretation of empirical results and the public policy towards natio...

  20. Revealing the programming process

    DEFF Research Database (Denmark)

    Bennedsen, Jens; Caspersen, Michael Edelgaard

    2005-01-01

    One of the most important goals of an introductory programming course is that the students learn a systematic approach to the development of computer programs. Revealing the programming process is an important part of this; however, textbooks do not address the issue -- probably because...... the textbook medium is static and therefore ill-suited to expose the process of programming. We have found that process recordings in the form of captured narrated programming sessions are a simple, cheap, and efficient way of providing the revelation.We identify seven different elements of the programming...

  1. TypeScript revealed

    CERN Document Server

    Maharry, Dan

    2013-01-01

    TypeScript Revealed is a quick 100-page guide to Anders Hejlsberg's new take on JavaScript. With this brief, fast-paced introduction to TypeScript, .NET, Web and Windows 8 application developers who are already familiar with JavaScript will easily get up to speed with TypeScript and decide whether or not to start incorporating it into their own development. TypeScript is 'JavaScript for Application-scale development'; a superset of JavaScript that brings to it an additional object-oriented-like syntax familiar to .NET programmers that compiles down into simple, clean JavaScript that any browse

  2. Android Emotions Revealed

    DEFF Research Database (Denmark)

    Vlachos, Evgenios; Schärfe, Henrik

    2012-01-01

    This work presents a method for designing facial interfaces for sociable android robots with respect to the fundamental rules of human affect expression. Extending the work of Paul Ekman towards a robotic direction, we follow the judgment-based approach for evaluating facial expressions to test in...... which case an android robot like the Geminoid|DK –a duplicate of an Original person- reveals emotions convincingly; when following an empirical perspective, or when following a theoretical one. The methodology includes the processes of acquiring the empirical data, and gathering feedback on them. Our...... findings are based on the results derived from a number of judgments, and suggest that before programming the facial expressions of a Geminoid, the Original should pass through the proposed procedure. According to our recommendations, the facial expressions of an android should be tested by judges, even in...

  3. Chemistry of plutonium revealed

    International Nuclear Information System (INIS)

    In 1941 one goal of the Manhattan Project was to unravel the chemistry of the synthetic element plutonium as rapidly as possible. In this paper the work carried out at Berkeley from the spring of 1942 to the summer of 1945 is described briefly. The aqueous chemistry of plutonium is quite remarkable. Important insights were obtained from tracer experiments, but the full complexity was not revealed until macroscopic amounts (milligrams) became available. Because processes for separation from fission products were based on aqueous solutions, such solution chemistry was emphasized, particularly precipitation and oxidation-reduction behavior. The latter turned out to be unusually intricate when it was discovered that two more oxidation states existed in aqueous solution than had previously been suspected. Further, an equilibrium was rapidly established among the four aqueous oxidation states, while at the same time any three were not in equilibrium. These and other observations made while doing a crash study of a previously unknown element are reported

  4. Revealing Cosmic Rotation

    CERN Document Server

    Yadav, Amit P S; Keating, Brian G

    2012-01-01

    Cosmological Birefringence (CB), a rotation of the polarization plane of radiation coming to us from distant astrophysical sources, may reveal parity violation in either the electromagnetic or gravitational sectors of the fundamental interactions in nature. Until only recently this phenomenon could be probed with only radio observations or observations at UV wavelengths. Recently, there is a substantial effort to constrain such non-standard models using observations of the rotation of the polarization plane of cosmic microwave background (CMB) radiation. This can be done via measurements of the $B$-modes of the CMB or by measuring its TB and EB correlations which vanish in the standard model. In this paper we show that $EB$ correlations-based estimator is the best for upcoming polarization experiments. The $EB$ based estimator surpasses other estimators because it has the smallest noise and of all the estimators is least affected by systematics. Current polarimeters are optimized for the detection of $B$-mode...

  5. Clinal effects of LASIK on binocular vision in myopic anisometropia%近视性屈光参差患者LASIK术后双眼视功能评估

    Institute of Scientific and Technical Information of China (English)

    杨亮; 胡琦; 康杨; 黄磊; 王珂萌

    2012-01-01

    目的 观察近视性屈光参差患者接受准分子激光原位角膜磨镶术( LASIK)后双眼视功能的变化,探讨LASIK手术矫治近视性屈光参差对三级视功能的影响,从双眼视觉的变化评价其临床应用价值.设计前瞻性病例系列.研究对象36例(72眼)行LASIK手术的近视性屈光参差患者(双眼屈光参差≥2.50 D).方法 对36例行LASIK手术的近视性屈光参差患者分别于手术前和手术后3个月进行裸眼视力、最佳矫正视力、屈光状态和同视机双眼视功能的检测,并对双眼视功能的变化进行随访研究.主要指标手术前后裸眼视力、最佳矫正视力、屈光度、同时视、融合功能、远立体视和近立体视.结果 术前72眼的裸跟视力在0.01-0.2之间,术后3个月时均达到1.0.双跟屈光参差由术前的(5.01±1.96)D( 2.50~9.00 D),降低到术后3个月的( 0.28±0.22 )D(0.00~0.75 D).手术前后的屈光参差度的改变,差异均有显著统计学意义(P<0.01).26例屈光参差量≥2.50 D且≤6.00 D的高度屈光参差者术前戴框架眼镜下近立体视正常的12例,术后3个月增至22例,差异有统计学意义(P<0.05);16例屈光参差量>6.0D的重度屈光参差者手术前后均没有正常近立体视.术前戴框架眼镜下三级视功能(同时视、融合功能、远立体视)正常的分别为33例、18例、13例,LASIK术后3个月三级视功能正常的分别为34例、33例、23例,手术后获得融合功能和远立体视者较术前明显增加(P均<0.05).结论 LASIK矫治近视性屈光参差,不仅可提高患者裸眼视力,而且可通过减小患者双眼间的屈光差异,增加双眼物像的融合,改善立体视功能.%Objective To analyze the clinical effects on binocular vision after LASIK for myopic anisomelropia, and evaluate its clinical value in the view of vision quality. Design Prospective case series. Participants 36 cases (72 eyes) with myopic anisometropia who received

  6. Pattern adaptation of relay cells in the lateral geniculate nucleus of binocular and monocular vision-deprived cats%双眼和单眼视觉剥夺猫外膝体细胞的图形适应

    Institute of Scientific and Technical Information of China (English)

    王伟; 寿天德

    2000-01-01

    为测定丘脑外膝体细胞的图形适应是否依赖于早期视觉经验, 在细胞外记录了双眼和单眼缝合的猫外膝体中继细胞对长时间运动光栅刺激的反应. 在双眼剥夺猫,占68%的记录到的细胞在30 s内反应下降到稳定值,其平均反应值下降33%,适应程度较正常猫显著.在单眼剥夺猫,记录到的剥夺眼驱动的和非剥夺眼驱动的细胞中,分别有占53%和44%的细胞显示图形适应, 两者差别不大.研究表明, 早期视剥夺能增强或保持图形适应, 提示图形适应是外膝体细胞常见的固有性质,可能主要由遗传因素所决定.%To test whether the pattern adaptation in thalamus is dependent upon postnatal visual experience during early life, the responses of relay cells to prolonged drifting grating stimulation were recorded extracellularly from the dorsal lateral geniculate nucleus (dLGN) of cats reared with binocular and monocular lid suture. In binocular vision-deprived cats, 68% of cells recorded showed significant adaptation to prolonged grating stimuli within 30 s, with a mean response decrease of 33%, and then stabilized gradually. This adaptation was stronger than that of relay cells in normal cats. In monocular vision-deprived cats, 53% of the cells driven by the deprived eye showed similar adaptation as did 44% of the cells driven by the non-deprived eye. These results indicate that pattern adaptation could be maintained or even enhanced after visual deprivation in early life. It is suggested that pattern adaptation is a general and intrinsic property of the dLGN cells, which may be mainly determined by genetic factors.

  7. Diffuse optical intracluster light as a measure of stellar tidal stripping: The cluster CL0024+17 at z ∼ 0.4 observed at the large binocular telescope

    Energy Technology Data Exchange (ETDEWEB)

    Giallongo, E.; Menci, N.; Grazian, A.; Gallozzi, S.; Castellano, M.; Fiore, F.; Fontana, A.; Pentericci, L.; Boutsia, K.; Paris, D.; Speziali, R.; Testa, V. [INAF—Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio (Italy)

    2014-01-20

    We have evaluated the diffuse intracluster light (ICL) in the central core of the galaxy cluster CL0024+17 at z ∼ 0.4 observed with the prime focus camera (Large Binocular Camera) at the Large Binocular Telescope. The measure required an accurate removal of the galaxies' light within ∼200 kpc from the center. The residual background intensity has then been integrated in circular apertures to derive the average ICL intensity profile. The latter shows an approximate exponential decline as expected from theoretical cold dark matter models where the ICL is due to the integrated contribution of light from stars that are tidally stripped from the halo of their host galaxies due to encounters with other galaxies in the cluster cold dark matter (CDM) potential. The radial profile of the ICL over the galaxies intensity ratio (ICL fraction) is increasing with decreasing radius, but near the cluster center it starts to bend and then decreases where the overlap of the halos of the brightest cluster galaxies becomes dominant. Theoretical expectations in a simplified CDM scenario show that the ICL fraction profile can be estimated from the stripped over galaxy stellar mass ratio in the cluster. It is possible to show that the latter quantity is almost independent of the properties of the individual host galaxies but mainly depends on the average cluster properties. The predicted ICL fraction profile is thus very sensitive to the assumed CDM profile, total mass, and concentration parameter of the cluster. Adopting values very similar to those derived from the most recent lensing analysis in CL0024+17, we find a good agreement with the observed ICL fraction profile. The galaxy counts in the cluster core have then been compared with that derived from composite cluster samples in larger volumes, up to the clusters virial radius. The galaxy counts in the CL0024+17 core appear flatter and the amount of bending with respect to the average cluster galaxy counts imply a loss of

  8. Diffuse optical intracluster light as a measure of stellar tidal stripping: The cluster CL0024+17 at z ∼ 0.4 observed at the large binocular telescope

    International Nuclear Information System (INIS)

    We have evaluated the diffuse intracluster light (ICL) in the central core of the galaxy cluster CL0024+17 at z ∼ 0.4 observed with the prime focus camera (Large Binocular Camera) at the Large Binocular Telescope. The measure required an accurate removal of the galaxies' light within ∼200 kpc from the center. The residual background intensity has then been integrated in circular apertures to derive the average ICL intensity profile. The latter shows an approximate exponential decline as expected from theoretical cold dark matter models where the ICL is due to the integrated contribution of light from stars that are tidally stripped from the halo of their host galaxies due to encounters with other galaxies in the cluster cold dark matter (CDM) potential. The radial profile of the ICL over the galaxies intensity ratio (ICL fraction) is increasing with decreasing radius, but near the cluster center it starts to bend and then decreases where the overlap of the halos of the brightest cluster galaxies becomes dominant. Theoretical expectations in a simplified CDM scenario show that the ICL fraction profile can be estimated from the stripped over galaxy stellar mass ratio in the cluster. It is possible to show that the latter quantity is almost independent of the properties of the individual host galaxies but mainly depends on the average cluster properties. The predicted ICL fraction profile is thus very sensitive to the assumed CDM profile, total mass, and concentration parameter of the cluster. Adopting values very similar to those derived from the most recent lensing analysis in CL0024+17, we find a good agreement with the observed ICL fraction profile. The galaxy counts in the cluster core have then been compared with that derived from composite cluster samples in larger volumes, up to the clusters virial radius. The galaxy counts in the CL0024+17 core appear flatter and the amount of bending with respect to the average cluster galaxy counts imply a loss of

  9. 基于双目视觉的关键点的检测方法及定位研究%Study on Key Point Detection and Localization Based on Binocular Vision

    Institute of Scientific and Technical Information of China (English)

    于乃功; 马春燕; 林佳

    2011-01-01

    以双目立体视觉测量为背景,以显著性标志物中的关键点为目标,提出了基于颜色阈值分割的关键点的实时检测和定位方法;关键点的检测和定位主要分为3个过程,一是图像的预处理部分,为后续的检测和定化提供基础;二是对预处理后的图像进行关键点检测,检测的方法首先分别通过颜色阈值分割、轮廓提取、多边形逼近以及设置矩形轮廓提取出关键点所在的显著性标志物,其次根据该显著性标志物的特点,采用hough变换提取线段,并通过最小二乘法进行直线拟合,求出关键点的精确的像素坐标; 三是利用立体视觉三角测量原理,对求取的关键点进行精确的位姿计算;该方法实时性好、精度高,为后续的机器人视觉避障提供了一定的理论依据.%With the background of binocular stereo vision measurement and aiming at key point of obvious marker, a method based on color segmentation for key point detection and localization is presented. The detection and localization of key point includes three parts. The first part is image preprocessing for the following detection and localization. The second is key point detection, the detection method is through color segmentation, contour extraction, polygonal approximation, setting rectangular boundary and find the obvious marker. Then according to the feature of the obvious marker, we adopt Hough line segment detection, then fits the edge points by Lease Square Error (LSE) method, The coordinates of the key points are calculated by the equations of lines. Finally, the distance and orientation from camera to the key point is acquired accurately based on triangulation of binocular vision. The experiment result shows that the method greatly improves accuracy and real -time performance. It provides foundation for obstacle-avoidance of mobile robot .

  10. Brain networks underlying bistable perception.

    Science.gov (United States)

    Baker, Daniel H; Karapanagiotidis, Theodoros; Coggan, David D; Wailes-Newson, Kirstie; Smallwood, Jonathan

    2015-10-01

    Bistable stimuli, such as the Necker Cube, demonstrate that experience can change in the absence of changes in the environment. Such phenomena can be used to assess stimulus-independent aspects of conscious experience. The current study used resting state functional magnetic resonance imaging (rs-fMRI) to index stimulus-independent changes in neural activity to understand the neural architecture that determines dominance durations during bistable perception (using binocular rivalry and Necker cube stimuli). Anterior regions of the Superior Parietal Lobule (SPL) exhibited robust connectivity with regions of primary sensorimotor cortex. The strength of this region's connectivity with the striatum predicted shorter dominance durations during binocular rivalry, whereas its connectivity to pre-motor cortex predicted longer dominance durations for the Necker Cube. Posterior regions of the SPL, on the other hand, were coupled to associative cortex in the temporal and frontal lobes. The posterior SPL's connectivity to the temporal lobe predicted longer dominance during binocular rivalry. In conjunction with prior work, these data suggest that the anterior SPL contributes to perceptual rivalry through the inhibition of incongruent bottom up information, whereas the posterior SPL influences rivalry by supporting the current interpretation of a bistable stimulus. Our data suggests that the functional connectivity of the SPL with regions of sensory, motor, and associative cortex allows it to regulate the interpretation of the environment that forms the focus of conscious attention at a specific moment in time. PMID:26123379

  11. Is Quantum Mechanics needed to explain consciousness ?

    CERN Document Server

    Thomsen, Knud

    2007-01-01

    In this short comment to a recent contribution by E. Manousakis [1] it is argued that the reported agreement between the measured time evolution of conscious states during binocular rivalry and predictions derived from quantum mechanical formalisms does not require any direct effect of QM. The recursive consumption analysis process in the Ouroboros Model can yield the same behavior.

  12. Puerto Rico Revealed Preference data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Revealed preference models provide insights into recreational angler behavior and the economic value of recreational fishing trips. Revealed preference data is...

  13. Revealed Cores: Characterizations and Structure

    OpenAIRE

    Stefano Vannucci

    2010-01-01

    Characterizations of the choice functions that select the cores or the externally stable cores induced by an underlying revealed dominance digraph are provided. Relying on such characterizations, the basic order-theoretic structure of the corresponding sets of revealed cores is also analyzed

  14. APPLICATION OF BINOCULAR VISION TECHNOLOGY IN STRUCTURAL PARTS SIZE MEASUREMENT%双目视觉技术在结构件尺寸测量中的应用

    Institute of Scientific and Technical Information of China (English)

    侯跃谦; 李冠楠; 谭庆昌

    2013-01-01

    In this paper, we discuss the engineering applications and the detection model of structural parts measurement using machine vi -sion, and propose a method to detect the size of the structural parts based on binocular vision .We use the improved solution of cameras ’ in-ternal and external parameters to calibrate the effective focal length of the single camera , and estimate the fundamental matrix by using an op-timised method in which the distance between the pixel coordinate and the corresponding epipolar line is the objective function .Through the singular value decomposition of essential matrix , rotation matrix and translation vector between two cameras are obtained .Under laboratory conditions , the space distance between two adjacent cams on same camshaft of a light vehicle is conducted practical measurement .The results show that the measurement method is able to achieve the accuracy requirement of monitoring the cam spacing in composite camshaft .%对结构件视觉测量的工程应用、检测模型进行讨论,提出一种双目视觉检测结构件空间尺寸的方法。应用改进的求解摄像机内外参数的方法对单摄像机有效焦距进行标定,应用以像素坐标到对应的极线距离为目标函数的优化方法对基本矩阵进行了估算,通过对本质矩阵的奇异值分解得到两个摄像机之间的旋转矩阵和平移向量。实验室条件下对轻型车凸轮轴凸轮间距空间尺寸进行了实际测量,结果表明,测量方法能够达到监测组合式凸轮轴凸轮间距的要求。

  15. Interocular conflict attracts attention.

    Science.gov (United States)

    Paffen, Chris L E; Hessels, Roy S; Van der Stigchel, Stefan

    2012-02-01

    During binocular rivalry, perception alternates.between dissimilar images presented dichoptically. Since.its discovery, researchers have debated whether the phenomenon is subject to attentional control. While it is now clear that attentional control over binocular rivalry is possible, the opposite is less evident: Is interocular conflict (i.e., the situation leading to binocular rivalry) able to attract attention?In order to answer this question, we used a change blindness paradigm in which observers looked for salient changes in two alternating frames depicting natural scenes. Each frame contained two images: one for the left and one for the right eye. Changes occurring in a single image (monocular) were detected faster than those occurring in both images (binocular). In addition,monocular change detection was also faster than detection in fused versions of the changed and unchanged regions. These results show that interocular conflict is capable of attracting attention, since it guides visual attention toward salient changes that otherwise would remain unnoticed for longer. The results of a second experiment indicated that interocular conflict attracts attention during the first phase of presentation, a phase during which the stimulus is abnormally fused [added]. PMID:22167536

  16. Urticarial vasculitis reveals unsuspected thyroiditis.

    Science.gov (United States)

    Ferreira, Olga; Mota, Alberto; Baudrier, Teresa; Azevedo, Filomena

    2012-01-01

    A 38-year-old woman presented with erythematous, violaceous plaques with a serpiginous and unusual appearance located on the left shoulder, left thigh, and right buttock, evolving for 5 days, which eventually became generalized. A skin biopsy revealed leukocytoclastic vasculitis and a diagnosis of urticarial vasculitis was made. The complete blood count, biochemistry, complement levels, and other immunological test results were unremarkable. However, antithyroid antibody titers were increased. Despite having normal thyroid function tests and an absence of specific symptoms, the patient underwent a thyroid ultrasound, which revealed features of thyroiditis, and was subsequently referred to an endocrinologist. Several diseases can be associated with urticarial vasculitis, namely infections and autoimmune connective-tissue disorders such as systemic lupus erythematosus and Sjögren syndrome. Thyroiditis is an uncommon association. PMID:23000939

  17. Decision Making and Revealed Preference

    DEFF Research Database (Denmark)

    de la Rosa, Leonidas Enrique

    If our decision-making processes are to some extent shaped by evolutionary pressures and our environment is different from that to which we adapted, some of our choices will not be in our best interest. But revealed preference is the only tool that we have so far to conduct a normative analysis. ....... Given advances in evolutionary psychology and neuroscience, I propose one way to model those evolutionary pressures that will hopefully prove useful in expanding normative economics.......If our decision-making processes are to some extent shaped by evolutionary pressures and our environment is different from that to which we adapted, some of our choices will not be in our best interest. But revealed preference is the only tool that we have so far to conduct a normative analysis...

  18. Lipid sorting revealed by SANS

    International Nuclear Information System (INIS)

    We have investigated the lipid sorting in a binary small unilamellar vesicle (SUV) composed of cone-shaped (1,2-dihexanoyl-sn-glycero-3-phosphocholine: DHPC) and cylinder-shaped (1,2-dipalmitoyl-sn-glycero-3-phosphocholine: DPPC) lipids. In order to reveal the lipid sorting we adopted a contrast matching technique of small angle neutron scattering (SANS), which extracts the distribution of deuterated lipids in the bilayer quantitatively. The SANS profile of deuterated SUVs at the contrast matching condition showed a characteristic scattering profile, indicating an asymmetric distribution of cone-shaped lipids in the bilayer. The fitting of the observed SANS profile revealed that most DHPC molecules are localized in the outer leaflet, which supports that the shape of the lipid is strongly coupled with the membrane curvature. We compared the obtained asymmetric distribution of the cone-shaped lipids in the bilayer with the theoretical prediction based on the curvature energy model. (author)

  19. Revealing and Concealing in Antiquity

    DEFF Research Database (Denmark)

    Secrecy and the act of concealing and revealing knowledge effectually segregate the initiated and the uninitiated. The act of sharing or hiding knowledge plays a central role in all human relations private or public, political or religious. This volume explores the concept of secrecy and its impl...... the concept of secrecy and its potential for illuminating the agendas behind identity constructions, political propaganda, literary works, religous practices and shared history....

  20. Binocular depth perception in the pigeon.

    OpenAIRE

    McFadden, S A; Wild, J. M.

    1986-01-01

    By means of a discrete-trial simultaneous discrimination procedure, pigeons were trained to respond differentially to visual arrays that were identical except that one of them contained a circle displaced in depth when viewed stereoscopically. Performance was severely disrupted when one eye was occluded. The monocular deficit was peculiar to the depth task, inasmuch as no such decrement was seen on a pattern discrimination. The results imply that presence of the displaced circle was discrimin...

  1. Enclosure rotation on the Large Binocular Telescope

    Science.gov (United States)

    Howard, James; Meeks, Robert; Ashby, David; Davison, Warren; Wiese, James; Urban, Jeff; Hansen, Rick; Schuh, Jared

    2012-09-01

    After several years of operation the enclosure rotation system of the LBT is exhibiting wear and other performance issues that may impact operations. This paper reviews the system design and assumptions used, describes the current performance and observed symptoms, and discusses recent improvements made to improve performance and reliability. The rotating enclosure of the LBT is a 2200 ton structure riding on four bogies with a total of 20 wheels. Identified deficiencies include wheel bearing capacities, bogie misalignment, and rail loading. These are partially due to excess enclosure weight, which was supposed to be 1600 tons, but also due to design errors. The most serious problem was the failure of several wheel bearings. The bearings were not designed for field serviceability, so a crash program began to determine how to replace them. This got us back on sky quickly, but a review of the engineering calculations identified an error which led to the use of undersized bearings. A method of installing a larger bearing was found, and these have been installed. One set of bogie wheels are misaligned so severely the structure makes loud popping and banging noises when the direction of building rotation changes. The bogie needs to be rotated about its vertical axis, but there was no provision in the design for this. The circular rail the bogies roll on is wearing faster than expected. The rails are extremely difficult to replace, so the short term plan is to study the problem.

  2. Transparency masters for mathematics revealed

    CERN Document Server

    Berman, Elizabeth

    1980-01-01

    Transparency Masters for Mathematics Revealed focuses on master diagrams that can be used for transparencies for an overhead projector or duplicator masters for worksheets. The book offers information on a compilation of master diagrams prepared by John R. Stafford, Jr., audiovisual supervisor at the University of Missouri at Kansas City. Some of the transparencies are designed to be shown horizontally. The initial three masters are number lines and grids that can be used in a mathematics course, while the others are adaptations of text figures which are slightly altered in some instances. The

  3. Numerical Simulation Which is Single Particle in the Flow of Binoculars Suffered Difference Rotational Inertia Force%双筒水流中单颗粒差异旋转惯性力的数值模拟

    Institute of Scientific and Technical Information of China (English)

    张雪宁; 牧振伟

    2015-01-01

    On the basis of the physical model experiment,using DPM model to simulate the Taylor vortex cell experiments and using Moving Mesh in binoculars and concentric rotating flow simulation,the paper discussed the motion characteristics and force law of single particles. Simulation results show that a)in the rotation system,the smaller the flow rate is,the more obvious trend of single particles centrifugal movement will be;b)When the continuous rotation of the inner cylinder,the outer cylinder is stationary,difference rotational inertia force is less than centrifugal force in numerical,but they belong to the same orders of magnitude and in the same direction,single particle do centrif-ugal movement,when the continuous rotation of the inner cylinder and then still and outer cylinder is stationary,differences in rotational iner-tia force and the centrifugal force are in the opposite direction,differences in rotational inertia force is greater than centrifugal force,both dif-fer an order of magnitude,single particle do centripetal movement;c)Whether the inner cylinder is continuous rotation or stationary after the first rotation,Reynolds gradually decrease and the radial force affects the single particle state of motion.%在实体模型试验的基础上,采用 DPM多相流模型模拟泰勒窝胞试验,并将滑移网格运用于同心双筒旋转水流模拟,对水流中单颗粒的运动进行了数值模拟,探讨了单颗粒的运动特性与受力规律。模拟结果表明:①旋转水流体系中水流速度越小,单颗粒发生离心运动的趋势越明显;②当内筒持续旋转、外筒静止时,差异旋转惯性力在数值上小于离心力,但二者属于同一个数量级且方向相同,单颗粒做离心运动,当内筒持续旋转再静止、外筒静止时,差异旋转惯性力与离心力方向相反,在数值上差异旋转惯性力大于离心力,单颗粒做向心运动;③无论内筒是持续旋转还是先旋转

  4. Características estruturais maculares de olhos de pré-escolares nascidos prematuros: análise por tomografia de coerência óptica e oftalmoscopia binocular indireta

    Directory of Open Access Journals (Sweden)

    Lígia Beatriz Bonotto

    2013-04-01

    Full Text Available OBJETIVO: Comparar a estrutura retiniana da mácula e fóvea entre prematuros com retinopatia da prematuridade (ROP estágios II e III pós-tratamento, com ROP estágios II e III regredida espontaneamente e sem ROP, através de exames de tomografia de coerência óptica (OCT e da oftalmoscopia binocular indireta (OBI. MÉTODOS: Estudo do tipo transversal, observacional e não cego. Foram incluídas crianças prematuras nascidas entre 06/1992 e 06/2006 e examinadas entre 06/2009 e 12/2010; idade gestacional menor ou igual a 32 semanas e peso ao nascer menor ou igual a 1.599 g; com mínimo de três consultas durante o período de seleção; sem retinopatia da prematuridade ou com diagnóstico de ROP estágios II ou III em pelo menos um dos olhos com regressão espontânea ou após tratamento; máximo de seis meses de idade cronológica para o primeiro exame no serviço; idade cronológica mínima de quatro anos no período da reavaliação. Foram excluídas crianças prematuras que não compareceram ou que não tinham condições clínicas para a realização dos exames de reavaliação. Os prematuros foram divididos em três grupos: G1- com ROP pós-tratamento; G2- com ROP pós-regressão espontânea; e G3- sem ROP. Os exames realizados foram OBI e OCT. RESULTADOS: Vinte e quatro prematuros (48 olhos apresentaram os critérios exigidos para a pesquisa, com idade média cronológica entre 5 e 6 anos. À OBI, houve diferença estatística significativa para a presença de alterações na retina dos prematuros do grupo G1. No entanto estas alterações corresponderam às lesões cicatriciais deixadas pelo tratamento da ROP, sem comprometimento visível da região macular. À OCT houve diferença estatística significativa para a maior espessura foveal para os prematuros do grupo G1. Considerando-se o olho esquerdo, não houve diferença estatística significativa relacionada à espessura da fóvea entre G1 e G3. Não houve diferença entre os tr

  5. 近视眼不同矫正方式的双眼视功能研究%Study of binocular function between spectacle and soft contact lens correction on myope

    Institute of Scientific and Technical Information of China (English)

    鲁智莉; 王岳秀; 于芳蕾; 殷路; 孔繁学

    2012-01-01

    [目的]探讨近视眼戴框架眼镜和角膜接触镜矫正的双眼视功能及其区别.[方法]选取近视眼63例,按习惯矫正方式分为框架眼镜矫正和角膜接触镜矫正两组,Von Graefe法测量每位近视的远、近距离水平隐斜,梯度性AC/A比率,远、近距离正、负融像性聚散,比较两组各参数差异.[结果]戴框架眼镜和角膜接触镜两组的近距离水平隐斜分别为(-7.33 ±3.67)△、(-4.12±3.35)△,AC/A比率分别为(2.69±1.78)△/D、(4.34±1.68)△/D,两组差异均有显著性意义(P<0.05),戴角膜接触镜近距离水平隐斜、AC/A比率更接近正常水平.戴角膜接触镜近距离负融像性聚散(21.32±5.12)△较戴框架眼镜组(17.14±6.03)△增大,两组差异有显著性意义(P<0.05);远距离水平隐斜,远距离正、负融像性聚散、近距离正融像性聚散两组比较差异无显著性意义(P>0.05).[结论]近视戴角膜接触镜矫正,近距离水平隐斜、AC/A比率较戴框架眼镜更接近正常值.%[ Objective ] To study the binocular function of myope with spectacle and soft contact lens and the difference between them. [Methods] Sixty -three myopes were selected in the study and divided into two groups according to the conventional correction way. Distance and near horizontal phoria, AC/A ratio, distance and near fusional vergence were measured in all subjects. [Results] Near horizontal phoria and near negative fusional vergence were ( - 7. 33 ±3. 67) , (17. 14 ±6.03)△ wearing spectacle. Those were(-4. 12 ±3. 35)△ , (21. 32 ±5. 12) △with soft contact lens , respectively. AC/A ratio were (2. 69 ± 1. 78) △/D, (4. 34 ± 1. 68) △/D in the two groups. Statistically significant differences were found with soft contact lens correction in comparison to spectacle in near horizontal phoria, AC/A ratio and near negative fusional vergence(P0. 05). [Conclusion] Soft contact lens correction in myope reduces near exophoria, increases AC/A ratio and

  6. Plan competitions reveal entrepreneurial talent

    Energy Technology Data Exchange (ETDEWEB)

    Madison, Alison L.

    2011-05-15

    Monthly economic diversity column for Tri-City Herald business section. Excerpt below: There’s something to be said for gaining valuable real-world experience in a structured, nurturing environment. Take for instance learning to scuba dive in the comfort of my resort pool rather than immediately hanging out with sharks while I figure out little things like oxygen tanks and avoiding underwater panic attacks. Likewise, graduate students are getting some excellent, supportive real-world training through university business plan competitions. These competitions are places where smart minds, new technologies, months of preparation and coaching, and some healthy pre-presentation jitters collide to reveal not only solid new business ideas, but also some promising entrepreneurial talent. In fact, professionals from around our region descend upon college campuses every spring to judge these events, which help to bridge the gap between academics and the real technology and business-driven economy.

  7. The chemistry of plutonium revealed

    International Nuclear Information System (INIS)

    In 1941 one goal of the Manhattan Project was to unravel the chemistry of the synthetic element plutonium as rapidly as possible. Important insights were obtained from tracer experiments, but the full complexity of plutonium chemistry was not revealed until macroscopic amounts (milligrams) became available. Because processes for separation from fission products were aqueous solution based, such solution chemistry was emphasized, particularly precipitation and oxidation-reduction behavior. The latter turned out to be unusually intricate when it was discovered that two more oxidation states existed in aqueous solution than had previously been suspected. Further, it was found that an equilibrium was rapidly established among the four aqueous oxidation states while at the same time any three were not in equilibrium. These and other observations made while doing a crash study of a previously unknown element will be reported

  8. Archimedes: Accelerator Reveals Ancient Text

    International Nuclear Information System (INIS)

    Archimedes (287-212 BC), who is famous for shouting 'Eureka' (I found it) is considered one of the most brilliant thinkers of all times. The 10th-century parchment document known as the 'Archimedes Palimpsest' is the unique source for two of the great Greek's treatises. Some of the writings, hidden under gold forgeries, have recently been revealed at the Stanford Synchrotron Radiation Laboratory at SLAC. An intense x-ray beam produced in a particle accelerator causes the iron in original ink, which has been partly erased and covered, to send out a fluorescence glow. A detector records the signal and a digital image showing the ancient writings is produced. Please join us in this fascinating journey of a 1,000-year-old parchment from its origin in the Mediterranean city of Constantinople to a particle accelerator in Menlo Park.

  9. Reveal for Salmonella test system.

    Science.gov (United States)

    Bird, C B; Miller, R L; Miller, B M

    1999-01-01

    The Reveal for Salmonella (RSS) test system is a presumptive qualitative test that detects the presence of Salmonella organisms in foods within 21 h total testing time, allowing the user to release negative products 24 h earlier than when using other rapid test kits. Foods are enriched with a proprietary resuscitation medium called Revive and then selectively enriched with either Selenite Cystine or Rappaport-Vassiliadis selective media. The enriched culture is used to inoculate the RSS detection device, which initiates a lateral flow through a reagent zone containing anti-Salmonella antibodies conjugated to colloidal gold particles that capture antigens present in the culture. The antigen-antibody complex migrates farther and is captured by an additional anti-Salmonella antibody, causing the colloidal gold to precipitate and form a visual line, indicating a positive result. A procedural control line also will form regardless of the presence of Salmonella organisms to indicate the test is working properly. Existing AOAC Official Methods for Salmonella organisms require a 48 h enrichment before testing. Hence, a food product has to be held before release, adding extra cost to the company and the consumer. The RSS test system was evaluated by quantitative spiking studies. Although AOAC encourages inclusion of naturally contaminated foods, almost all microbiological AOAC validation studies have been performed with artificially contaminated foods for absolute control over the study. The RSS test system is designed to test many food types for Salmonella organisms and has a limit of detection of 5-10 colony-forming units (cfu)/25 g with a false-negative rate of < 1% and a false-positive rate of < 5.0%. It showed an 81% overall agreement with the traditional procedure of the U.S. Department of Agriculture's Food Safety Inspection Service. PMID:10367381

  10. Focus groups reveal consumer ambivalence.

    Science.gov (United States)

    1983-01-01

    According to qualitative research, Salvadoreans are ambivalent about the use of contraceptives. Since complete responsibility for management of the CSM project was accepted by the Association Demografica Salvadorena (ADS), the agency which operates the contraceptive social marketing project in El Salvador, in November 1980, the need for decisions in such areas as product price increases, introduction of new condom brands, promotion of the vaginal foaming tablet, and assessment of product sales performance had arisen. The ICSMP funded market research, completed during 1983, was intended to provide the data on which such decisions by ADS could be based. The qualitative research involved 8 focus groups, comprised of men and women, aged 18-45, contraceptive users and nonusers, from the middle and lower socioeconomic strata of the city of San Salvador and other suburban areas. In each group a moderator led discussion of family planning and probed respondents for specific attitudes, knowledge, and behavior regarding the use of contraceptives. To assess attitudes at a more emotional level, moderators asked respondents to "draw" their ideas on certain issues. A marked discrepancy was revealed between respondents' intellectual responses to the issues raised in group discussion, as opposed to their feelings expressed in the drawings. Intellectually, participants responded very positively to family planning practice, but when they were asked to draw their perceptions, ambivalent feelings emerged. Drawings of both the user and the nonuser convey primarily negative aspects for either choice. The user is tense and moody toward her children; the nonuser loses her attractiveness and "dies." Figures also show drawings of some of the attitudes of single and married male participants. 1 drawing shows an incomplete and a complete circle, symbolizing a sterilized man (incomplete) and a nonsterilized man (complete). Another picture depicts a chained man who has lost his freedom

  11. How Much of the Unconscious Is Just Pre - Threshold?

    Directory of Open Access Journals (Sweden)

    Manfred Wilhem Fahle

    2011-10-01

    Full Text Available Visual awareness is a specific form of consciousness. Binocular rivalry, the alternation of visual consciousness resulting when the two eyes view differing stimuli, allows one to experimentally investigate visual awareness. Observers usually indicate the gradual changes of conscious perception in binocular rivalry by a binary measure: pressing a button. However, in our experiments, gradual measures such as pupil and joystick movements start around 590 ms before observers press a button, apparently accessing even pre-conscious processes. Our gradual measures permit monitoring the built-up, over time, of decision processes and that should not be considered as abrupt events. Changes in analogue measures occurring before button presses signalling decisions do not prove these decisions are taken subconsciously – eliminating free will - but just prepared pre-thresholdly.

  12. Differences of accommodative responses between two eyes under binocular viewing condition mediated by polarizing glasses%偏光镜介导的双眼注视状态下调节反应差异性研究

    Institute of Scientific and Technical Information of China (English)

    王瑞卿; 张妍; 胡娱新; 何宇茜; 纪冬梅; 王淑荣

    2016-01-01

    variance analysis of repeated measuring and t test.RESULTS:Significant differences of accommodative responses between the two eyes were found under condition ( 1 ) and ( 2 ) at all the fixating distance. The accommodative responses in used eyes which can see the visual target were higher than in non-used eyes which cannot see the visual target ( P 0. 05).CONCLUSlON:Ciliary muscles in the used eyes were more relatively tonic than non - used eyes under binocular open viewing condition. The imbalance of accommodative responses between two eyes may be one of the risk factors resulting into the occurrence of myopia.

  13. Continuous flash suppression reduces negative afterimages

    OpenAIRE

    Tsuchiya, Naotsugu; Koch, Christof

    2005-01-01

    Illusions that produce perceptual suppression despite constant retinal input are used to manipulate visual consciousness. Here we report on a powerful variant of existing techniques, continuous flash suppression. Distinct images flashed successively at approx10 Hz into one eye reliably suppress an image presented to the other eye. The duration of perceptual suppression is at least ten times greater than that produced by binocular rivalry. Using this tool we show that the strength of the negat...

  14. Conscious experience of a face without face-specific neural activity

    OpenAIRE

    Leon Deouell; Shlomo Bentin

    2008-01-01

    Understanding how conscious coherent percepts are formed from the sensory input is one of the most important goals of neuroscience. However, as frequently illustrated by visual illusions, conscious perception is not a direct reflection of the sensory input, and major parts of the input may evade conscious awareness. A dramatic demonstration of dissociation between sensory input and conscious perception occurs in binocular rivalry (BR): when each eye is presented with a different input, the tw...

  15. Breaking Continuous Flash Suppression: A New Measure of Unconscious Processing during Interocular Suppression?

    OpenAIRE

    Stein, Timo; Hebart, Martin N; Sterzer, Philipp

    2011-01-01

    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 continuous flash suppression” (b-CFS) p...

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

    OpenAIRE

    Timo eStein; Hebart, Martin N; Philipp eSterzer

    2011-01-01

    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 uncon...

  17. Fear modulates visual awareness similarly for facial and bodily expressions

    OpenAIRE

    Stienen, Bernard M. C.; Beatrice ede Gelder

    2011-01-01

    BackgroundSocial interaction depends on a multitude of signals carrying information about the emotional state of others. Past research has focused on the perception of facial expressions while perception of whole body signals has only been studied recently. The relative importance of facial and bodily signals is still poorly understood. In order to better understand the relative contribution of affective signals from the face only or from the rest of the body we used a binocular rivalry exper...

  18. Reduced GABAergic Action in the Autistic Brain.

    Science.gov (United States)

    Robertson, Caroline E; Ratai, Eva-Maria; Kanwisher, Nancy

    2016-01-11

    An imbalance between excitatory/inhibitory neurotransmission has been posited as a central characteristic of the neurobiology of autism [1], inspired in part by the striking prevalence of seizures among individuals with the disorder [2]. Evidence supporting this hypothesis has specifically implicated the signaling pathway of the inhibitory neurotransmitter, γ-aminobutyric acid (GABA), in this putative imbalance: GABA receptor genes have been associated with autism in linkage and copy number variation studies [3-7], fewer GABA receptor subunits have been observed in the post-mortem tissue of autistic individuals [8, 9], and GABAergic signaling is disrupted across heterogeneous mouse models of autism [10]. Yet, empirical evidence supporting this hypothesis in humans is lacking, leaving a gulf between animal and human studies of the condition. Here, we present a direct link between GABA signaling and autistic perceptual symptomatology. We first demonstrate a robust, replicated autistic deficit in binocular rivalry [11], a basic visual function that is thought to rely on the balance of excitation/inhibition in visual cortex [12-15]. Then, using magnetic resonance spectroscopy, we demonstrate a tight linkage between binocular rivalry dynamics in typical participants and both GABA and glutamate levels in the visual cortex. Finally, we show that the link between GABA and binocular rivalry dynamics is completely and specifically absent in autism. These results suggest a disruption in inhibitory signaling in the autistic brain and forge a translational path between animal and human models of the condition. PMID:26711497

  19. North-South competition, policy rivalry and profitability

    OpenAIRE

    Satya P. Das; Subhadip Ghosh

    2003-01-01

    In the strategic trade policy literature, the firms typically make positive profits at equilibrium policy levels. We show that this is not always true when firms from the developed (North) and developing (South) countries compete in the Northern market. In particular, the South firm may be pushed out of the Northern market. On the other hand, the Northern firm always maintains a market share in the South market in policy equilibrium. The critical assumption is that the Northern firms produce ...

  20. On merger profitability and the intensity of rivalry

    OpenAIRE

    Escrihuela-Villar, Marc

    2015-01-01

    This paper considers a general symmetric quantity-setting oligopoly where the "coefficient of cooperation" defined by Cyert and DeGroot (An Analysis of Cooperation and Learning in a Duopoly Context, 1973) is interpreted as the parameter indicating severity of competition. It is obtained that horizontal mergers are more likely to be profitable in a more competitive market structure. Consequently, the results by Salant, Switzer and Reynolds (The Effects of an Exogenous Change in Industry Struct...

  1. [Henry Toussaint and Louis Pasteur. Rivalry over a vaccine].

    Science.gov (United States)

    Chevallier-Jussiau, Nadine

    2010-01-01

    Henry Toussaint (1847-1890) is a veterinary who studied in Veterinary School of Lyon with his great master Auguste Chauveau the famous physiologist. This place is the First School founded in Europe at the end of the XVIIIth century and has opened a way of thinking. His carrer brilliant and rich begins first in Lyon and then when he is named Professor of Anatomy and Physiology at the Veterinary School of Toulouse. Doctor of Science and Doctor of Medecine Toussaint applies "the experimental method" to his research in his laboratory and makes a lot of publications. He starts with Anatomy, then Physiology and soon he prioritizes his research to infestious diseases which cause serious damage to cattle in this time. He developes his own methods about anthrax an its "bacteridie", its nature, its way of culture and especially he studies the physiopathology of this disease. Pasteur is a renowned scientist who does study Microbiology at the same time in his laboratory in Paris, and precisely anthrax. He has explained his theories about "microbes" and has predominant advice. Toussaint admires Pasteur; in the year 1879 he finds first and isolates the microbe of "cholera des poules" (now Pasteurella) and gives Pasteur this new germ which will be used by Pasteur for his particular works about reducing of virulence by successive subcultures. In 1880 with his publishing on July 12 at the Academy of Science, Toussaint presents his successful result with an attenuated vaccine against anthrax: he has got protection against anthrax for dogs and sheep by using a vaccine which he has reduced off virulence by chemical manner. Academy congratulates him. Pasteur jealous of one's reputation contests the demonstration of Toussaint because he does not believe in the chemical method too different from his tests but will make use of this method for an experience open to the public in Pouilly-le-Fort in 1881. After this promotional event Pasteur will product and sell vaccines maked in his laboratory in Paris with the first chemical method of Toussaint. Pasteur gets glory and money. In the following time Toussaint tries another research on tuberculosis but soon he feels the first attacks of a neurologic illness and inescapably his mind declines until the death in 1890. PMID:20527335

  2. Are differences between twins a result of mutual rivalry?

    Science.gov (United States)

    Borg, J G

    1997-01-01

    The sexual index included in the Szondi test makes it possible to define the domains of an individual's "internal sex" or gender-especially the degree of the subject's bisexuality. This index was employed in a comparison between partners reared together in 62 monozygotic and 23 dizygotic pairs of twins. The observed incongruence in 1/3 MZ pairs would not appear to derive totally from errors of measurement. In most of these pairs it is competition which underlies the incongruence seen on the sexual index. It was further observed that the congruence here as in general in female pairs is clearly more marked than in males. A hypothesis was proposed, whereby competition for dominance is a distinctively major-tonality (masculinity) characteristic. The incongruence is more conspicuous among males because males are in general more markedly major-toned than females. This hypothesis was borne out. It is thus necessary here as in general to adopt two sex variables in parallel: external (i.e. matricular) sex and internal sex (gender). It is due to the presence of these competitive pairs that the means and especially deviations of twins' test results will consistently diverge from those in the population at large. PMID:9298156

  3. Sibling rivalry in the E2F family.

    Science.gov (United States)

    Trimarchi, Jeffrey M; Lees, Jacqueline A

    2002-01-01

    The E2F transcription factor family determines whether or not a cell will divide by controlling the expression of key cell-cycle regulators. The individual E2Fs can be divided into distinct subgroups that act in direct opposition to one another to promote either cellular proliferation or cell-cycle exit and terminal differentiation. What is the underlying molecular basis of this 'push-me-pull-you' regulation, and what are its biological consequences? PMID:11823794

  4. Sibling rivalry among paralogs promotes evolution of the human brain

    OpenAIRE

    Tyler-Smith, Chris; Xue, Yali

    2012-01-01

    Geneticists have long sought to identify the genetic changes that made us human, but pinpointing the functional-relevant changes has been challenging. Two papers in this issue suggest that partial duplication of SRGAP2, producing an incomplete protein that antagonizes the original, contributed to human brain evolution.

  5. Sibling rivalry among paralogs promotes evolution of the human brain.

    Science.gov (United States)

    Tyler-Smith, Chris; Xue, Yali

    2012-05-11

    Geneticists have long sought to identify the genetic changes that made us human, but pinpointing the functionally relevant changes has been challenging. Two papers in this issue suggest that partial duplication of SRGAP2, producing an incomplete protein that antagonizes the original, contributed to human brain evolution. PMID:22579279

  6. Sibling rivalry: training effects, emergence of dominance and incomplete control

    OpenAIRE

    Benhaiem, S.; Hofer, H; Kramer-Schadt, S.; Brunner, E.; East, M.L.

    2012-01-01

    Within-brood or -litter dominance provides fitness-related benefits if dominant siblings selfishly skew access to food provided by parents in their favour. Models of facultative siblicide assume that dominants exert complete control over their subordinate sibling’s access to food and that control is maintained, irrespective of the subordinate’s hunger level. By contrast, a recent functional hypothesis suggests that subordinates should contest access to food when the cost of not do...

  7. Sibling rivalry: training effects, emergence of dominance and incomplete control.

    Science.gov (United States)

    Benhaiem, Sarah; Hofer, Heribert; Kramer-Schadt, Stephanie; Brunner, Edgar; East, Marion L

    2012-09-22

    Within-brood or -litter dominance provides fitness-related benefits if dominant siblings selfishly skew access to food provided by parents in their favour. Models of facultative siblicide assume that dominants exert complete control over their subordinate sibling's access to food and that control is maintained, irrespective of the subordinate's hunger level. By contrast, a recent functional hypothesis suggests that subordinates should contest access to food when the cost of not doing so is high. Here, we show that within spotted hyena (Crocuta crocuta) twin litters, dominants most effectively skew access to maternal milk in their favour when their aggression prompts a highly submissive response. When hungry, subordinates were less submissive in response to aggression, thereby decreasing lost suckling time and increasing suckling time lost by dominants. In a species where adult females socially dominate adult males, juvenile females were more often dominant than males in mixed-sex litters, and subordinate sisters used more effective counter-tactics against dominant brothers than subordinate brothers against dominant sisters. Our results provide, to our knowledge, the first evidence in a mammal that dominant offspring in twin litters do not exert complete control over their sibling's access to resources (milk), and that sibling dominance relationships are influenced by sibling sex and training effects. PMID:22719032

  8. English Language Cultures in Bulgaria: A Linguistic Sibling Rivalry?

    Science.gov (United States)

    O'Reilly, Laurie M.

    1998-01-01

    In Bulgaria, a complex matrix of power relations governs English language education, and a triangle of international and intercultural relations between Bulgaria, United States, and United Kingdom. In the context of the changing economic and political milieu of central and eastern Europe, a study examines how Bulgaria fits into the emerging…

  9. Sibling Rivalry: A Look at Switzerland with PISA Data

    OpenAIRE

    Wolter, Stefan C.; Coradi Vellacott, Maja

    2002-01-01

    In this paper we analyse the sibling size and birth-order effect on educational achievement in Switzerland on the basis of PISA data. We find an overall modest size and birth-order effect. The sibling size effect, however, is a product of a substantial and significant negative size effect for families with lower socio-economic status and foreign origin and a positive sibling size effect in small, native families with a high socio-economic status compared to singlechild families with the same ...

  10. Is sibling rivalry fatal?: siblings and mortality clustering.

    Science.gov (United States)

    Kippen, Rebecca; Walters, Sarah

    2012-01-01

    Evidence drawn from nineteenth-century Belgian population registers shows that the presence of similarly aged siblings competing for resources within a household increases the probability of death for children younger than five, even when controlling for the preceding birth interval and multiple births. Furthermore, in this period of Belgian history, such mortality tended to cluster in certain families. The findings suggest the importance of segmenting the mortality of siblings younger than five by age group, of considering the presence of siblings as a time-varying covariate, and of factoring mortality clustering into analyses. PMID:22530254

  11. SiblingRivalry: Online Autotuning Through Local Competitions

    OpenAIRE

    Ansel, Jason Andrew; Pacula, Maciej; Wong, Yee Lok; Chan, CY; Olszewski, Marek; O'Reilly, Una-May; Amarasinghe, Saman P.

    2012-01-01

    Modern high performance libraries, such as ATLAS and FFTW, and programming languages, such as PetaBricks, have shown that autotuning computer programs can lead to significant speedups. However, autotuning can be burdensome to the deployment of a program, since the tuning process can take a long time and should be re-run whenever the program, microarchitecture, execution environment, or tool chain changes. Failure to re-autotune programs often leads to widespread use of sub-optimal algorithms....

  12. Cell cycle sibling rivalry: Cdc2 vs. Cdk2.

    Science.gov (United States)

    Kaldis, Philipp; Aleem, Eiman

    2005-11-01

    It has been long believed that the cyclin-dependent kinase 2 (Cdk2) binds to cyclin E or cyclin A and exclusively promotes the G1/S phase transition and that Cdc2/cyclin B complexes play a major role in mitosis. We now provide evidence that Cdc2 binds to cyclin E (in addition to cyclin A and B) and is able to promote the G1/S transition. This new concept indicates that both Cdk2 and/or Cdc2 can drive cells through G1/S phase in parallel. In this review we discuss the classic cell cycle model and how results from knockout mice provide new evidence that refute this model. We focus on the roles of Cdc2 and p27 in regulating the mammalian cell cycle and propose a new model for cell cycle regulation that accommodates these novel findings. PMID:16258277

  13. Russian-Swedish Maritime Rivalry in XVIII cen.

    Directory of Open Access Journals (Sweden)

    Sergey A. Kolotov

    2014-03-01

    Full Text Available The paper analyzes the military-technical aspect of Russian-Swedish confrontation of the XVIII cen. Given short chronology of hostilities and influence the characteristics of the ships on the results of campaigns.

  14. Elusive Rivalry? Conceptions of the Philosophy of Education

    Science.gov (United States)

    White, John

    2010-01-01

    What is analytical philosophy of education (APE)? And what has been its place in the history of the subject over the past 50 years? In a recent essay in "Ethics and Education" (Vol. 2, No. 2, October 2007) on 'Rival conceptions of the philosophy of education', Paul Standish described a number of features of APE. Relying on both historical and…

  15. US-Soviet Global Rivalry: Norms of Competition

    OpenAIRE

    Alexander L. George

    1986-01-01

    This paper examines alternative approaches for developing norms of competition that might help to avoid war-threatening confrontations between the superpowers. Analysis of the abortive Nixon-Brezh nev experiment with 'general principles' and of subsequent efforts to devise general 'codes of conduct' to regulate the US-Soviet global competition suggests that such approaches are not workable. The paper argues that more attention should be given by the superpowers to a 'case-by-case' approach th...

  16. The 'revealed preferences' theory: Assumptions and conjectures

    International Nuclear Information System (INIS)

    Being kind of intuitive psychology the 'Revealed-Preferences'- theory based approaches towards determining the acceptable risks are a useful method for the generation of hypotheses. In view of the fact that reliability engineering develops faster than methods for the determination of reliability aims the Revealed-Preferences approach is a necessary preliminary help. Some of the assumptions on which the 'Revealed-Preferences' theory is based will be identified and analysed and afterwards compared with experimentally obtained results. (orig./DG)

  17. Revealing advantage in a quantum network

    Science.gov (United States)

    Mukherjee, Kaushiki; Paul, Biswajit; Sarkar, Debasis

    2016-07-01

    The assumption of source independence was used to reveal nonlocal (apart from standard Bell-CHSH scenario) nature of correlations generated in entanglement swapping experiments. In this work, we have discussed the various utilities of this assumption to reveal nonlocality (via generation of nonbilocal correlations) and thereby exploiting quantumness under lesser requirements compared to some standard means of doing the same. We have also provided with a set of sufficient criteria, imposed on the states (produced by the sources) under which source independence can reveal nonbilocal nature of correlations in a quantum network.

  18. Saturn's Rings Reveal Unexpected Phenomena

    Institute of Scientific and Technical Information of China (English)

    李颖

    2004-01-01

    Safely in orbit around Saturn, NASA's Cassini spacecraft sent back its first close-up images of the massive planet's rings on July 1, revealing an unexpectedly varied terrain featuring surprisingly sharp edges, braids and delicate ridges.

  19. Do markets reveal preferences or shape them?

    OpenAIRE

    Isoni, Andrea; Brooks, Peter; Loomes, Graham; Sugden, Robert

    2016-01-01

    We contrast the proposition that markets reveal independently-existing preferences with the alternative possibility that they may help to shape them. Using demand-revealing experimental market institutions, we separate the shaping effects of price cues from the effects of market discipline. We find that individual valuations and prevailing prices are systematically affected by both exogenous manipulations of price expectations and endogenous but divergent price feedback. These effects persist...

  20. Spinal Cord Compression Revealing an Intraosseous Schwannoma

    OpenAIRE

    Leila Metoui; Faïda Ajili; Mouna Maiza; Mehdi Ben Ammar; Imen Gharsallah; Issam M'sakni; Bassem Louzir; Salah Othmani

    2013-01-01

    A 68-year-old female presented with inflammatory lumbalgia and cruralgia. Physical examination revealed a lumbar stiffness without neurological deficit. Secondarily, paraplegia and urinary retention appeared. Magnetic resonance imaging showed a vertebral compaction of L3 vertebra with medullar compression. Emergent surgery revealed an epidural tumor involving largely the L3 vertebral body. Histology found schwannoma with positive protein S100 on the immunohistochemical study. Metastasis scree...

  1. REVEAL: Software Documentation and Platform Migration

    Science.gov (United States)

    Wilson, Michael A.; Veibell, Victoir T.

    2011-01-01

    The Research Environment for Vehicle Embedded Analysis on Linux (REVEAL) is reconfigurable data acquisition software designed for network-distributed test and measurement applications. In development since 2001, it has been successfully demonstrated in support of a number of actual missions within NASA's Suborbital Science Program. Improvements to software configuration control were needed to properly support both an ongoing transition to operational status and continued evolution of REVEAL capabilities. For this reason the project described in this report targets REVEAL software source documentation and deployment of the software on a small set of hardware platforms different from what is currently used in the baseline system implementation. This presentation specifically describes the actions taken over a ten week period by two undergraduate student interns and serves as an overview of the content of the final report for that internship.

  2. Cardiac hydatid cyst revealed by ventricular tachycardia

    OpenAIRE

    Ibn Elhadj, Zied; Boukhris, Marouane; Kammoun, Ikram; Halima, Afef Ben; Addad, Faouzi; Kachboura, Salem

    2013-01-01

    Hydatid disease is a human parasitic infestation caused by the larval stage of Echinococcus Granulosus. The liver and the lungs are the most common locations. Cardiac involvement is rare and accounts for 0.5–2% of all hydatid disease. We report an unusual presentation of cardiac hydatid cyst revealed by ventricular tachycardia in a patient with a history of cerebral hydatid cyst.

  3. Consumer choice and revealed bounded rationality

    OpenAIRE

    Manzini, Paola; Mariotti, Marco

    2006-01-01

    We study two boundedly rational procedures in consumer behavior. We show that these procedures can be detected by conditions on observable demand data of the same type as standard revealed preference axioms. This provides the basis for a non-parametric analysis of boundedly rational consumer behavior mirroring the classical one for utility maximization.

  4. Eye Movements Reveal Dynamics of Task Control

    Science.gov (United States)

    Mayr, Ulrich; Kuhns, David; Rieter, Miranda

    2013-01-01

    With the goal to determine the cognitive architecture that underlies flexible changes of control settings, we assessed within-trial and across-trial dynamics of attentional selection by tracking of eye movements in the context of a cued task-switching paradigm. Within-trial dynamics revealed a switch-induced, discrete delay in onset of…

  5. Motion-induced blindness and Troxler fading: common and different mechanisms.

    Directory of Open Access Journals (Sweden)

    Yoram S Bonneh

    Full Text Available Extended stabilization of gaze leads to disappearance of dim visual targets presented peripherally. This phenomenon, known as Troxler fading, is thought to result from neuronal adaptation. Intense targets also disappear intermittently when surrounded by a moving pattern (the "mask", a phenomenon known as motion-induced blindness (MIB. The similar phenomenology and dynamics of these disappearances may suggest that also MIB is, likewise, solely due to adaptation, which may be amplified by the presence of the mask. Here we directly compared the dependence of both phenomena on target contrast. Observers reported the disappearance and reappearance of a target of varying intensity (contrast levels: 8%-80%. MIB was induced by adding a mask that moved at one of various different speeds. The results revealed a lawful effect of contrast in both MIB and Troxler fading, but with opposite trends. Increasing target contrast increased (doubled the rate of disappearance events for MIB, but decreased the disappearance rate to half in Troxler fading. The target mean invisible period decreased equally strongly with target contrast in MIB and in Troxler fading. The results suggest that both MIB and Troxler are equally affected by contrast adaptation, but that the rate of MIB is governed by an additional mechanism, possibly involving antagonistic processes between neuronal populations processing target and mask. Our results link MIB to other bi-stable visual phenomena that involve neuronal competition (such as binocular rivalry, which exhibit an analogous dependency on the strength of the competing stimulus components.

  6. Motion-induced blindness and Troxler fading: common and different mechanisms.

    Science.gov (United States)

    Bonneh, Yoram S; Donner, Tobias H; Cooperman, Alexander; Heeger, David J; Sagi, Dov

    2014-01-01

    Extended stabilization of gaze leads to disappearance of dim visual targets presented peripherally. This phenomenon, known as Troxler fading, is thought to result from neuronal adaptation. Intense targets also disappear intermittently when surrounded by a moving pattern (the "mask"), a phenomenon known as motion-induced blindness (MIB). The similar phenomenology and dynamics of these disappearances may suggest that also MIB is, likewise, solely due to adaptation, which may be amplified by the presence of the mask. Here we directly compared the dependence of both phenomena on target contrast. Observers reported the disappearance and reappearance of a target of varying intensity (contrast levels: 8%-80%). MIB was induced by adding a mask that moved at one of various different speeds. The results revealed a lawful effect of contrast in both MIB and Troxler fading, but with opposite trends. Increasing target contrast increased (doubled) the rate of disappearance events for MIB, but decreased the disappearance rate to half in Troxler fading. The target mean invisible period decreased equally strongly with target contrast in MIB and in Troxler fading. The results suggest that both MIB and Troxler are equally affected by contrast adaptation, but that the rate of MIB is governed by an additional mechanism, possibly involving antagonistic processes between neuronal populations processing target and mask. Our results link MIB to other bi-stable visual phenomena that involve neuronal competition (such as binocular rivalry), which exhibit an analogous dependency on the strength of the competing stimulus components. PMID:24658600

  7. Orbital tumor revealing a systemic sarcoidosis.

    Directory of Open Access Journals (Sweden)

    Samia Hannanachi Sassi

    2015-03-01

    Full Text Available Ocular involvement is seen in approximately 25% of patients with sarcoidosis. Uveitis is the most common ocular manifestation, but sarcoidosis may involve any part of the eye. Orbital manifestations of sarcoidosis are uncommon with few series in the literature. A 65-year-old woman presented with redness of the right eye and painless, unilateral eyelid swelling. Orbital scanning revealed mass infiltrating the soft tissue of the inferior right orbital quadrant. Biopsy results showed nodular, noncaseating granulomas consistent with sarcoidosis. The complete systemic workup revealed systemic manifestations of sarcoidosis at the time of examination with hilar and mediastinal lymphadenopathies noted on CT scan. The orbital surgical treatment was followed by systemic prednisone therapy with good response. Although rare, orbital sarcoidosis must be considered in the evaluation of orbital tumors in elderly patients. A search for systemic findings should be undertaken and appropriate therapy should be instituted.

  8. Orbital tumor revealing a systemic sarcoidosis.

    Science.gov (United States)

    Hannanachi Sassi, Samia; Dhouib, Rim; Kanchal, Fatma; Doghri, Raoudha; Boujelbene, Nadia; Bouguila, Hedi; Mrad, Karima

    2015-01-01

    Ocular involvement is seen in approximately 25% of patients with sarcoidosis. Uveitis is the most common ocular manifestation, but sarcoidosis may involve any part of the eye. Orbital manifestations of sarcoidosis are uncommon with few series in the literature. A 65-year-old woman presented with redness of the right eye and painless, unilateral eyelid swelling. Orbital scanning revealed mass infiltrating the soft tissue of the inferior right orbital quadrant. Biopsy results showed nodular, noncaseating granulomas consistent with sarcoidosis. The complete systemic workup revealed systemic manifestations of sarcoidosis at the time of examination with hilar and mediastinal lymphadenopathies noted on CT scan. The orbital surgical treatment was followed by systemic prednisone therapy with good response. Although rare, orbital sarcoidosis must be considered in the evaluation of orbital tumors in elderly patients. A search for systemic findings should be undertaken and appropriate therapy should be instituted. PMID:25796029

  9. Botswana’s revealed comparative advantage

    OpenAIRE

    Makochekanwa, Albert

    2007-01-01

    Analysis of Botswana’s competitiveness in world trade has been presented based on indices of revealed comparative advantage (RCA) calculated for the period 1999 and 2004. Results show that Botswana has RCA in diamonds, copper matte, and meat of bovine animals, among other products. Changes in values of RCA over time reinforce the dynamic nature of comparative advantage. The study established that the country gained comparative specialization in the following products: sugar products; copper o...

  10. Mammalian phylogeny reveals recent diversification rate shifts

    OpenAIRE

    Stadler, Tanja

    2011-01-01

    Phylogenetic trees of present-day species allow investigation of the rate of evolution that led to the present-day diversity. A recent analysis of the mammalian phylogeny challenged the view of explosive mammalian evolution after the Cretaceous–Tertiary (K/T) boundary (65 Mya). However, due to lack of appropriate methods, the diversification (speciation minus extinction) rates in the more recent past of mammalian evolution could not be determined. In this paper, I provide a method that reveal...

  11. Orbital tumor revealing a systemic sarcoidosis.

    OpenAIRE

    Samia Hannanachi Sassi; Rim Dhouib; Fatma Kanchal; Raoudha Doghri; Nadia Boujelbene; Hedi Bouguila; Karima Mrad

    2015-01-01

    Ocular involvement is seen in approximately 25% of patients with sarcoidosis. Uveitis is the most common ocular manifestation, but sarcoidosis may involve any part of the eye. Orbital manifestations of sarcoidosis are uncommon with few series in the literature. A 65-year-old woman presented with redness of the right eye and painless, unilateral eyelid swelling. Orbital scanning revealed mass infiltrating the soft tissue of the inferior right orbital quadrant. Biopsy results showed nodular, no...

  12. Driven Rydberg atoms reveal quartic level repulsion

    OpenAIRE

    Sacha, Krzysztof; Zakrzewski, Jakub

    2001-01-01

    The dynamics of Rydberg states of a hydrogen atom subject simultaneously to uniform static electric field and two microwave fields with commensurate frequencies is considered in the range of small fields amplitudes. In the certain range of the parameters of the system the classical secular motion of the electronic ellipse reveals chaotic behavior. Quantum mechanically, when the fine structure of the atom is taken into account, the energy level statistics obey predictions appropriate for the s...

  13. Driven Rydberg atoms reveal quartic level repulsion

    CERN Document Server

    Sacha, K; Sacha, Krzysztof; Zakrzewski, Jakub

    2001-01-01

    The dynamics of Rydberg states of a hydrogen atom subject simultaneously to uniform static electric field and two microwave fields with commensurate frequencies is considered in the range of small fields amplitudes. In the certain range of the parameters of the system the classical secular motion of the electronic ellipse reveals chaotic behavior. Quantum mechanically, when the fine structure of the atom is taken into account, the energy level statistics obey predictions appropriate for the symplectic Gaussian random matrix ensemble.

  14. Mediastinal Mature Teratoma Revealed by Empyema

    Directory of Open Access Journals (Sweden)

    Mohammed Raoufi

    2016-01-01

    Full Text Available Teratomas are germ cell tumors, manifested with a great variety of clinical features; the most common extragonadal site is the anterior mediastinum. In this case, we report the patient with a large mature mediastinal teratoma with several components of ectodermal and endothermal epithelium. A 24-year-old female patient presented with history of persistent chest pain and progressively aggravating dyspnea for the previous 3 months. A chest X-ray showed a large opacity of the entire left hemithorax. Transcutaneous needle aspiration revealed a purulent fluid. The tube thoracostomy was introduced and the effusion was evacuated. Some weeks later, patient was seen in emergency for persistent cough and lateral chest pain. CT scan revealed a mass of the left hemithorax. The mass showed heterogeneous density, without compressing mediastinum great vessels and left hilar structures. Lipase value was elevated in needle aspiration. The patient underwent a total resection of the mediastinum mass via a left posterolateral thoracotomy. Microscopy revealed a mature teratoma with cystic structures. The patient subsequently made a full recovery. This case provide benign mediastinal teratoma with total atelectasis of left lung and elevated lipase value in needle transcutaneous aspiration; this event is explained by pancreatic component in the cystic tumor. Total removal of the tumor is adequate treatment for this type of teratoma and the prognosis is excellent.

  15. Mediastinal Mature Teratoma Revealed by Empyema.

    Science.gov (United States)

    Raoufi, Mohammed; Herrak, Laila; Benali, Anas; Achaachi, Leila; El Ftouh, Mustapha; Bellarbi, Salma; Tilfine, Charaf; Taouarsa, Firdaous

    2016-01-01

    Teratomas are germ cell tumors, manifested with a great variety of clinical features; the most common extragonadal site is the anterior mediastinum. In this case, we report the patient with a large mature mediastinal teratoma with several components of ectodermal and endothermal epithelium. A 24-year-old female patient presented with history of persistent chest pain and progressively aggravating dyspnea for the previous 3 months. A chest X-ray showed a large opacity of the entire left hemithorax. Transcutaneous needle aspiration revealed a purulent fluid. The tube thoracostomy was introduced and the effusion was evacuated. Some weeks later, patient was seen in emergency for persistent cough and lateral chest pain. CT scan revealed a mass of the left hemithorax. The mass showed heterogeneous density, without compressing mediastinum great vessels and left hilar structures. Lipase value was elevated in needle aspiration. The patient underwent a total resection of the mediastinum mass via a left posterolateral thoracotomy. Microscopy revealed a mature teratoma with cystic structures. The patient subsequently made a full recovery. This case provide benign mediastinal teratoma with total atelectasis of left lung and elevated lipase value in needle transcutaneous aspiration; this event is explained by pancreatic component in the cystic tumor. Total removal of the tumor is adequate treatment for this type of teratoma and the prognosis is excellent. PMID:27144046

  16. Midface swelling reveals nasofrontal dermal sinus

    International Nuclear Information System (INIS)

    Nasofrontal dermal sinuses are very rare and generally occur in children. This congenital malformation can be revealed by midface swelling, which can be complicated by local infection or neuromeningitis. Such complications make the dermal sinus a life-threatening disease. Two cases of nasofrontal dermal sinuses are reported in this work. The first case is an 11-month-old girl who presented with left orbitonasal soft tissue swelling accompanied by inflammation. Physical examination found fever, left orbitonasal thickening, and a puncture hole letting out pus. Computed tomography revealed microabscesses located at the left orbitonasal soft tissues, a frontal bone defect, and an intracranial cyst. Magnetic resonance imaging showed the transosseous tract between the glabella and the brain and affirmed the epidermoid nature of the intracranial cyst. The second case is a 7-year-old girl who presented with a nasofrontal non-progressive mass that intermittently secreted a yellow liquid through an external orifice located at the glabella. MRI revealed a cystic mass located in the deep layer of the glabellar skin related to an epidermoid cyst with a nasofrontal dermal sinus tract. In both cases, surgical excision was performed, and pathological confirmation was made for the diagnoses of dermal sinuses. The postoperative course was favorable. Through these cases, the authors stress the role of imaging methods in confirming the diagnosis and looking for associated cysts (dermoid and epidermoid) to improve recognition of this rare disease. Knowledge of the typical clinical presentations, imaging manifestations, and most common sites of occurrence of this malformation are needed to formulate a differential diagnosis.

  17. Revealing digital documents. Concealed structures in data

    CERN Document Server

    Voß, Jakob

    2011-01-01

    This short paper gives an introduction to a research project to analyze how digital documents are structured and described. Using a phenomenological approach, this research will reveal common patterns that are used in data, independent from the particular technology in which the data is available. The ability to identify these patterns, on different levels of description, is important for several applications in digital libraries. A better understanding of data structuring will not only help to better capture singular characteristics of data by metadata, but will also recover intended structures of digital objects, beyond long term preservation.

  18. Interior Evolution of Ceres Revealed by Dawn

    Science.gov (United States)

    Raymond, Carol A.; Park, Ryan S.; Konopliv, Alex S.; Bland, Michael T.; Marchi, Simone; Castillo-Rogez, Julie C.; McCord, Thomas B.; Jaumann, Ralf; Russell, Christopher T.; Prettyman, Thomas H.

    2015-11-01

    Dawn's exploration of Ceres has revealed its geophysical characteristics, informing the processes that have shaped it. Dawn has determined the average diameter of Ceres to be 940 km, smaller than the previously estimated 975 km [1]. This implies a density of 2160 kg/m3, indicating that Ceres is less differentiated than predicted [2]. The low-degree gravity field is consistent with the body being in hydrostatic equilibrium and the magnitude of J2 implies some central condensation. Ceres' entire surface is cratered, implying the lack of a thick (10's of km) water ice layer at the surface. Variability in Ceres' crater morphology indicates that the near-surface layer has variable strength and rheology, likely due to heterogeneity in the near-surface mixture of rock, ice and salt. The lack of a number of expected large impact basins on Ceres can be interpreted to be the result of viscous relaxation, resurfacing or a combination of both. These data provide insights into Ceres' thermal evolution and mechanical properties, which appear to be unique to this warm, icy body.[1] Thomas, P. C., et al., Differentiation of the asteroid Ceres as revealed by its shape, Nature, 437, 224-226, 2005; [2] McCord et al., Ceres: Its Origin, Evolution and Structure and Dawn's Potential Contribution, Space Sci Rev DOI 10.1007/s11214-010-9729-9, 2011.

  19. Narratives and Emotions: Revealing and Concealing Laughter

    Directory of Open Access Journals (Sweden)

    Lena Marander-Eklund

    2008-08-01

    Full Text Available My paper deals with laughter as an expression of emotions in stories.I study laughter both as a communicative factor in fieldwork and as a stylistic device in narratives. When is laughter used as an effect in storytelling and what does this laughter mean? Is laughter always an expression of humour and comics? What else can it be an expression of? The stories that I use for analysing laughter are personal experience stories of giving birth. In these stories women use laughter in many ways, both in contact with me as an interviewer, together with me, and as a way of marking the meaning of the story. The women often laugh when they talk about corporeality, pain and difficulties during labour, but also when they perform a self-presentation with elements that “almost” happened during birth. What do they reveal or conceal with laughter in narratives and what can the laughter reveal about the point of their narration?

  20. North Korea's nuclear power programme revealed

    International Nuclear Information System (INIS)

    The extent of the nuclear programme in the Democratic People's Republic of Korea (DPRK) was revealed in May 1992: reports on the country's facilities were handed to the International Atomic Energy Agency and an Agency group visited Korea on a ''familiarisation visit''. DPRK's nuclear programme had been the subject of speculation for some time. While the country had signed the Non-Proliferation Treaty and two facilities were already under IAEA safeguards - a research reactor and a critical facility, both at the Institute of Nuclear Physics - there were a number of indicators that DPRK was pursuing a nuclear programme aimed at military use. The new openness was prompted by a number of factors including discussions on closer relations with South Korea. DPRK signed a comprehensive Safeguards Agreement on 30 January 1992. On the familiarisation visit by the IAEA director general in May the DPRK revealed nuclear facilities in operation or under construction at five sites. At Pakchon and Pyongsan: each site housed a uranium mine and uranium-ore concentration plant. At Pyongyang: the two facilities already under safeguards at the Institute of Nuclear Physics; and a sub critical facility at Kim Il Sung university. At Nyongbyon: a fuel fabrication plant; an 5MWe experimental power reactor, in operation; a 50MWe prototype power reactor under construction; and a facility ultimately intended as a reprocessing plant, but described by North Korea, because of its unfinished state, as a laboratory. At Taechon: a 200MWe power reactor under construction. (author)

  1. Transcriptome classification reveals molecular subtypes in psoriasis

    Directory of Open Access Journals (Sweden)

    Ainali Chrysanthi

    2012-09-01

    Full Text Available Abstract Background Psoriasis is an immune-mediated disease characterised by chronically elevated pro-inflammatory cytokine levels, leading to aberrant keratinocyte proliferation and differentiation. Although certain clinical phenotypes, such as plaque psoriasis, are well defined, it is currently unclear whether there are molecular subtypes that might impact on prognosis or treatment outcomes. Results We present a pipeline for patient stratification through a comprehensive analysis of gene expression in paired lesional and non-lesional psoriatic tissue samples, compared with controls, to establish differences in RNA expression patterns across all tissue types. Ensembles of decision tree predictors were employed to cluster psoriatic samples on the basis of gene expression patterns and reveal gene expression signatures that best discriminate molecular disease subtypes. This multi-stage procedure was applied to several published psoriasis studies and a comparison of gene expression patterns across datasets was performed. Conclusion Overall, classification of psoriasis gene expression patterns revealed distinct molecular sub-groups within the clinical phenotype of plaque psoriasis. Enrichment for TGFb and ErbB signaling pathways, noted in one of the two psoriasis subgroups, suggested that this group may be more amenable to therapies targeting these pathways. Our study highlights the potential biological relevance of using ensemble decision tree predictors to determine molecular disease subtypes, in what may initially appear to be a homogenous clinical group. The R code used in this paper is available upon request.

  2. Revealing effective classifiers through network comparison

    CERN Document Server

    Gallos, Lazaros K

    2014-01-01

    The ability to compare complex systems can provide new insight into the fundamental nature of the processes captured in ways that are otherwise inaccessible to observation. Here, we introduce the $n$-tangle method to directly compare two networks for structural similarity, based on the distribution of edge density in network subgraphs. We demonstrate that this method can efficiently introduce comparative analysis into network science and opens the road for many new applications. For example, we show how the construction of a phylogenetic tree across animal taxa according to their social structure can reveal commonalities in the behavioral ecology of the populations, or how students create similar networks according to the University size. Our method can be expanded to study a multitude of additional properties, such as network classification, changes during time evolution, convergence of growth models, and detection of structural changes during damage.

  3. Revealing effective classifiers through network comparison

    Science.gov (United States)

    Gallos, Lazaros K.; Fefferman, Nina H.

    2014-11-01

    The ability to compare complex systems can provide new insight into the fundamental nature of the processes captured, in ways that are otherwise inaccessible to observation. Here, we introduce the n-tangle method to directly compare two networks for structural similarity, based on the distribution of edge density in network subgraphs. We demonstrate that this method can efficiently introduce comparative analysis into network science and opens the road for many new applications. For example, we show how the construction of a “phylogenetic tree” across animal taxa according to their social structure can reveal commonalities in the behavioral ecology of the populations, or how students create similar networks according to the University size. Our method can be expanded to study many additional properties, such as network classification, changes during time evolution, convergence of growth models, and detection of structural changes during damage.

  4. Chemotaxis: new role for Ras revealed

    Institute of Scientific and Technical Information of China (English)

    Jianshe Yan; Dale Hereld; Tian Jin

    2010-01-01

    @@ A recent study of chemotaxis revealed a new role for the proto-oncogene Ras in the social ameba Dictyostelium discoideum.Chemotaxis,the directional movement of cells toward chemokines and other chemoattractants,plays critical roles in diverse physiological processes,such as mobilization of immune cells to fight invading microorganisms,targeting of metastatic cancer cells to specific tissues,and guidance of sperm cells to ova during fertilization.This work,published in the July 26 issue of The Journal of Cell Biology,was conducted in Dr.Devreotes' lab at John Hopkins University and Dr.Parent's lab at National Cancer Institute.This research team demonstrated that RasC functions as an upstream regulator of TORC2 and thereby governs the effects of TORC2-PKB signaling on the cytoskeleton and cell migration.

  5. Revealed Quantum Information in Weak Interaction Processes

    CERN Document Server

    Hiesmayr, B C

    2014-01-01

    We analyze the achievable limits of the quantum information processing of the weak interaction revealed by hyperons with spin. We find that the weak decay process corresponds to an interferometric device with a fixed visibility and fixed phase difference for each hyperon. Nature chooses rather low visibilities expressing a preference to parity conserving or violating processes (except for the decay $\\Sigma^+\\longrightarrow p \\pi^0$). The decay process can be considered as an open quantum channel that carries the information of the hyperon spin to the angular distribution of the momentum of the daughter particles. We find a simple geometrical information theoretic interpretation of this process: two quantization axes are chosen spontaneously with probabilities $\\frac{1\\pm\\alpha}{2}$ where $\\alpha$ is proportional to the visibility times the real part of the phase shift. Differently stated the weak interaction process corresponds to spin measurements with an imperfect Stern-Gerlach apparatus. Equipped with this...

  6. Social patterns revealed through random matrix theory

    Science.gov (United States)

    Sarkar, Camellia; Jalan, Sarika

    2014-11-01

    Despite the tremendous advancements in the field of network theory, very few studies have taken weights in the interactions into consideration that emerge naturally in all real-world systems. Using random matrix analysis of a weighted social network, we demonstrate the profound impact of weights in interactions on emerging structural properties. The analysis reveals that randomness existing in particular time frame affects the decisions of individuals rendering them more freedom of choice in situations of financial security. While the structural organization of networks remains the same throughout all datasets, random matrix theory provides insight into the interaction pattern of individuals of the society in situations of crisis. It has also been contemplated that individual accountability in terms of weighted interactions remains as a key to success unless segregation of tasks comes into play.

  7. Neutron Imaging Reveals Internal Plant Hydraulic Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Jeffrey [ORNL; Bilheux, Hassina Z [ORNL; Kang, Misun [ORNL; Voisin, Sophie [ORNL; Cheng, Chu-Lin [ORNL; Horita, Jusuke [ORNL; Perfect, Edmund [ORNL

    2013-01-01

    Many terrestrial ecosystem processes are constrained by water availability and transport within the soil. Knowledge of plant water fluxes is thus critical for assessing mechanistic processes linked to biogeochemical cycles, yet resolution of root structure and xylem water transport dynamics has been a particularly daunting task for the ecologist. Through neutron imaging, we demonstrate the ability to non-invasively monitor individual root functionality and water fluxes within Zea mays L. (maize) and Panicum virgatum L. (switchgrass) seedlings growing in a sandy medium. Root structure and growth were readily imaged by neutron radiography and neutron computed tomography. Seedlings were irrigated with water or deuterium oxide and imaged through time as a growth lamp was cycled on to alter leaf demand for water. Sub-millimeter scale resolution reveals timing and magnitudes of root water uptake, redistribution within the roots, and root-shoot hydraulic linkages, relationships not well characterized by other techniques.

  8. Ceres Revealed in a Grain of Salt

    Science.gov (United States)

    Zolensky, M. E.; Bodnar, R. J.; Chan, Q. H.-S.; Hagiya, K.; Komatsu, M.; Steele, A.; Fries, M.; Kebukawa, Y.; Mikouchi, T.; Ohsumi, K.

    2016-01-01

    Introduction: Zag and Monahans (1998) are H chondrite regolith breccias containing 4.5 giga-year-old halite crystals which contain abundant inclusions of aqueous fluids, solids and organics. These all originated on a cryo-volcanically-active C class asteroid, probably 1 Ceres; the halite was transported to the regolith of the H chondrite parent asteroid, potentially 6 Hebe. Detailed analysis of these solids will thus potentially reveal the mineralogy of Ceres. Mineralogy of solids in the Monahans Halite Solid grains are present in the halites, which were entrained within the mother brines during eruption, including material from the interior and surface of the erupting body. The solids include abundant, widely variable organics that could not have been significantly heated (which would have resulted in the loss of fluids from the halite). Our analyses by Raman microprobe, SEM/EDX, synchrotron X-ray diffraction, UPLC-FD/QToF-MS, C-XANES and TEM reveal that these trapped grains include macromolecular carbon (MMC) similar in structure to CV3 chondrite matrix carbon, aliphatic carbon compounds, olivine (Fo99-59), high- and low-Ca pyroxene, feldspars, phyllosilicates, magnetite, sulfides, metal, lepidocrocite, carbonates, diamond, apatite and zeolites. Conclusions: The halite in Monahans and Zag derive from a water and carbon-rich object that was cryo-volcanically active in the early solar system, probably Ceres. The Dawn spacecraft found that Ceres includes C chondrite materials. Our samples include both protolith and aqueously-altered samples of the body, permitting understanding of alteration conditions. Whatever the halite parent body, it was rich in a wide variety of organics and warm, liquid water at the solar system's dawn.

  9. Revealing source signatures in ambient BTEX concentrations

    International Nuclear Information System (INIS)

    Management of ambient concentrations of Volatile Organic Compounds (VOCs) is essential for maintaining low ozone levels in urban areas where its formation is under a VOC-limited regime. The significant decrease in traffic-induced VOC emissions in many developed countries resulted in relatively comparable shares of traffic and non-traffic VOC emissions in urban airsheds. A key step for urban air quality management is allocating ambient VOC concentrations to their pertinent sources. This study presents an approach that can aid in identifying sources that contribute to observed BTEX concentrations in areas characterized by low BTEX concentrations, where traditional source apportionment techniques are not useful. Analysis of seasonal and diurnal variations of ambient BTEX concentrations from two monitoring stations located in distinct areas reveal the possibility to identify source categories. Specifically, the varying oxidation rates of airborne BTEX compounds are used to allocate contributions of traffic emissions and evaporative sources to observed BTEX concentrations. - BTEX sources are identified from temporal variations of ambient concentration

  10. Revealing the values behind convenience food consumption.

    Science.gov (United States)

    Botonaki, Anna; Mattas, Konstadinos

    2010-12-01

    The increasing importance of convenience in consumer food choices has attracted researchers' interest. In the effort to understand how convenience affects consumers' food preferences, values are believed to play an important role. The present study attempts to examine the way personal values suggested by Schwartz (1992) are associated with behaviour and attitudes regarding convenience food. A number of constructs describing food related attitudes and behaviours were developed and their relationship with personal values was analyzed following the methodology proposed by Brunsø, Scholderer, and Grunert (2004). Data were collected through a questionnaire survey from a random sample of consumers in Thessaloniki city, Greece. The results reveal that convenience food consumption and convenience orientation in the food domain are mainly connected with values that motivate people to seek new experiences, act independently and enhance their own personal interests, while are in conflict with values of conservation and self-transcendence. The opposite holds for other food related attitudes and behaviours like involvement with cooking and variety in diet. The findings seem to be of particular interest not only for marketers of food products, but also for food policy makers. PMID:20875475

  11. ERYTHEMA NODOSUM REVEALING ACUTE MYELOID LEUKEMIA

    Directory of Open Access Journals (Sweden)

    Chebbi Wafa

    2013-07-01

    Full Text Available Introduction: Erythema nodosum (EN is the most common type of panniculitis. It may be idiopathic or secondary to various etiologies. However, the occurrence of erythema nodosum in malignant hemopathy had rarely been reported. Case report: A 42 year-old woman presented with a four week history of recurrent multiple painful erythematous nodules developed on the lower limbs associated with arthralgia of the ankles and fever. The clinical features of skin lesions with contusiform color evolution allowed establishing the diagnosis of EN. No underlying cause was found. The skin lesions were improved with non-steroidal anti-inflammatory drugs and colchicine. Three months later, the patient consulted for recurrence of EN associated with fever, inflammatory polyarthralgia and hepatosplenomegaly. The peripheral blood count revealed pancytopenia. A bone marrow examination confirmed the diagnosis of acute myeloid leukemia type 2. Initiation of chemotherapy was followed by the complete disappearance of skin lesions of EN. Conclusion: Paraneoplastic erythema nodosum is a rare entity. In the literature, a few cases of association with leukemia have been reported. Exploration for solid neoplasms or hemopathy in case of recurrent EN or resistance to conventional treatment should be systematic

  12. VISTA Reveals the Secret of the Unicorn

    Science.gov (United States)

    2010-10-01

    A new infrared image from ESO's VISTA survey telescope reveals an extraordinary landscape of glowing tendrils of gas, dark clouds and young stars within the constellation of Monoceros (the Unicorn). This star-forming region, known as Monoceros R2, is embedded within a huge dark cloud. The region is almost completely obscured by interstellar dust when viewed in visible light, but is spectacular in the infrared. An active stellar nursery lies hidden inside a massive dark cloud rich in molecules and dust in the constellation of Monoceros. Although it appears close in the sky to the more familiar Orion Nebula it is actually almost twice as far from Earth, at a distance of about 2700 light-years. In visible light a grouping of massive hot stars creates a beautiful collection of reflection nebulae where the bluish starlight is scattered from parts of the dark, foggy outer layers of the molecular cloud. However, most of the new-born massive stars remain hidden as the thick interstellar dust strongly absorbs their ultraviolet and visible light. In this gorgeous infrared image taken from ESO's Paranal Observatory in northern Chile, the Visible and Infrared Survey Telescope for Astronomy (VISTA [1], eso0949) penetrates the dark curtain of cosmic dust and reveals in astonishing detail the folds, loops and filaments sculpted from the dusty interstellar matter by intense particle winds and the radiation emitted by hot young stars. "When I first saw this image I just said 'Wow!' I was amazed to see all the dust streamers so clearly around the Monoceros R2 cluster, as well as the jets from highly embedded young stellar objects. There is such a great wealth of exciting detail revealed in these VISTA images," says Jim Emerson, of Queen Mary, University of London and leader of the VISTA consortium. With its huge field of view, large mirror and sensitive camera, VISTA is ideal for obtaining deep, high quality infrared images of large areas of the sky, such as the Monoceros R2 region

  13. NASA's Hyperwall Revealing the Big Picture

    Science.gov (United States)

    Sellers, Piers

    2011-01-01

    NASA:s hyperwall is a sophisticated visualization tool used to display large datasets. The hyperwall, or video wall, is capable of displaying multiple high-definition data visualizations and/or images simultaneously across an arrangement of screens. Functioning as a key component at many NASA exhibits, the hyperwall is used to help explain phenomena, ideas, or examples of world change. The traveling version of the hyperwall is typically comprised of nine 42-50" flat-screen monitors arranged in a 3x3 array (as depicted below). However, it is not limited to monitor size or number; screen sizes can be as large as 52" and the arrangement of screens can include more than nine monitors. Generally, NASA satellite and model data are used to highlight particular themes in atmospheric, land, and ocean science. Many of the existing hyperwall stories reveal change across space and time, while others display large-scale still-images accompanied by descriptive, story-telling captions. Hyperwall content on a variety of Earth Science topics already exists and is made available to the public at: eospso.gsfc.nasa.gov/hyperwall. Keynote and PowerPoint presentations as well as Summary of Story files are available for download on each existing topic. New hyperwall content and accompanying files will continue being developed to promote scientific literacy across a diverse group of audience members. NASA invites the use of content accessible through this website but requests the user to acknowledge any and all data sources referenced in the content being used.

  14. Saturn Probe: Revealing Solar System Origins

    Science.gov (United States)

    Spilker, T. R.

    2015-12-01

    Comparative studies of the gas giant and ice giant planets are needed to reliably discriminate among competing theories of the origin and evolution of giant planets and the solar system, but we lack critical measurements. A Saturn atmospheric entry probe mission would fill a vital part of that gap, allowing comparative studies of Jupiter and Saturn, providing the basis for later comparisons with the ice giants Uranus and Neptune, and informing studies of extrasolar planetary systems now being characterized. The Galileo Probe mission provided the first in situ studies of Jupiter's atmosphere. Similar measurements at Saturn, Uranus and Neptune would provide an important comparative planetology context for the Galileo results. Cassini's "Proximal Orbits" in 2017 will reveal Saturn's internal structure to complement the Juno mission's similar measurements at Jupiter. A Saturn entry probe, complementing the Galileo Probe investigations at Jupiter, would complete a solid basis for improved understanding of both Jupiter and Saturn, an important stepping stone to understanding Uranus and Neptune and solar system formation and evolution. The 2012 Decadal Survey ("DS") added Saturn Probe science objectives to NASA's New Frontiers Program: highest-priority Tier 1 objectives any New Frontiers implementation must achieve, and Tier 2, high priority but lower than Tier 1. A DS mission concept study using extremely conservative assumptions concluded that a Saturn Probe project could fit within New Frontiers resource constraints, giving a PI confidence that they could pursue some Tier 2 objectives, customizing for the proper balance of science return, science team composition, procured or contributed instruments, etc. Contributed instruments could significantly enhance the payload and the science team for greater science return. They also provide international collaboration opportunities, with science benefits well demonstrated by missions such as Cassini-Huygens and Rosetta.

  15. Application of binocular vision system in nuclear power plant

    International Nuclear Information System (INIS)

    Based on stereo disparity, a vision system of locating three-dimensional position is described. The input device of the vision system is a digital camera. And special targets are used to improve the efficiency and accuracy of computer analysis. It provides a reliable and practical computer locating system for equipment maintenance in nuclear power plant

  16. On binocular vision: The geometric horopter and Cyclopean eye.

    Science.gov (United States)

    Turski, Jacek

    2016-02-01

    We study geometric properties of horopters defined by the criterion of equality of angle. Our primary goal is to derive the precise geometry for anatomically correct horopters. When eyes fixate on points along a curve in the horizontal visual plane for which the vergence remains constant, this curve is the larger arc of a circle connecting the eyes' rotation centers. This isovergence circle is known as the Vieth-Müller circle. We show that, along the isovergence circular arc, there is an infinite family of horizontal horopters formed by circular arcs connecting the nodal points. These horopters intersect at the point of symmetric convergence. We prove that the family of 3D geometric horopters consists of two perpendicular components. The first component consists of the horizontal horopters parametrized by vergence, the point of the isovergence circle, and the choice of the nodal point location. The second component is formed by straight lines parametrized by vergence. Each of these straight lines is perpendicular to the visual plane and passes through the point of symmetric convergence. Finally, we evaluate the difference between the geometric horopter and the Vieth-Müller circle for typical near fixation distances and discuss its possible significance for depth discrimination and other related functions of vision that make use of disparity processing. PMID:26548811

  17. Exploring the Moon through binoculars and small telescopes

    CERN Document Server

    Cherrington, Ernest H

    1984-01-01

    Informative, profusely illustrated guide to locating and identifying craters, rills, seas, mountains, other lunar features. Newly revised and updated with special section of new photos. Over 100 photos and diagrams. ""Extraordinary delight awaits the amateur astronomer or teacher who opens this book."" - The Science Teacher.

  18. Moirés maintained internally by binocular vision.

    Science.gov (United States)

    Piggins, D

    1978-01-01

    Moiré patterns in depth are reported when spatially periodic stimuli are viewed stereoscopically. Near-vertical square-wave gratings with horizontal disparity effected by orientation difference produce a 'venetian blind' effect. A single grating is observed divided into horizontal layers, the number of layers being a direct function of orientation difference. Lines within each layer are slanted with respect to the frontoparallel plane, becoming more so with increasing orientation difference. Subjects with stereo deficits report a decreased effect. Quantitative reports implicate stereoscopic mechanisms responsible for this unique, internal preservation of moiré patterns. PMID:740508

  19. Passive seismology reveals biannual calving periodicity

    Science.gov (United States)

    Bartholomaus, T. C.; Larsen, C. F.; West, M. E.; Oneel, S.

    2013-12-01

    Iceberg calving is a large and variable component of the total mass loss from marine-terminating glaciers worldwide. However, the processes that control the size and variability of calving fluxes are poorly understood. Even more basic descriptions of iceberg calving, such as its seasonality, are uncertain. Here, we present nearly two years of automatically-estimated calving fluxes at Yahtse Glacier, a tidewater glacier whose terminus flows at ~7 km/yr towards the Gulf of Alaska. At the terminus, ice losses to calving and submarine melt total approximately 1.5 km^3/yr. In order to identify temporal variability in this mean rate, we develop a statistical model of calving size based on characteristics of calving-generated icequakes. These characteristics include 4 amplitude-based variables and 5 variables related to the shape of the icequake envelope. We build our model by combining automatically-detected icequakes (O'Neel et al., 2007) located at the terminus of Yahtse Glacier (Jones et al., 2013) with a training set of 1400 icequakes produced by visually-observed calving events (Bartholomaus et al., 2012). In each of the models tested (regression trees, multinomial logistic regression and multiple linear regession), icequake duration emerges as the single best predictor of iceberg size, consistent with past studies (Qamar, 1988; O'Neel et al., 2007). Additional predictors, such as the mean icequake amplitude and the kurtosis of the icequake envelope improve the predictive capability of the model and reduce the mean squared error to well-within the error of the in-person classification. Once validated, we apply our model to ~ 400,000 icequakes produced by calving events at Yahtse Glacier between June 2009 and September 2011. These results reveal fluctuations in calving rate at a range of timescales, including twice per year. We suggest that the roughly 50%, biannual variation in calving rate is the result of the trade-off between two competing processes at the

  20. Microradiometers Reveal Ocean Health, Climate Change

    Science.gov (United States)

    2013-01-01

    When NASA researcher Stanford Hooker is in the field, he pays close attention to color. For Hooker, being in the field means being at sea. On one such research trip to the frigid waters of the Arctic, with a Coast Guard icebreaker looming nearby and the snow-crusted ice shelf a few feet away, Hooker leaned over the edge of his small boat and lowered a tethered device into the bright turquoise water, a new product devised by a NASA partner and enabled by a promising technology for oceanographers and atmospheric scientists alike. Color is a function of light. Pure water is clear, but the variation in color observed during a visit to the beach or a flight along a coastline depends on the water s depth and the constituents in it, how far down the light penetrates and how it is absorbed and scattered by dissolved and suspended material. Hooker cares about ocean color because of what it can reveal about the health of the ocean, and in turn, the health of our planet. "The main thing we are interested in is the productivity of the water," Hooker says. The seawater contains phytoplankton, microscopic plants, which are the food base for the ocean s ecosystems. Changes in the water s properties, whether due to natural seasonal effects or human influence, can lead to problems for delicate ecosystems such as coral reefs. Ocean color can inform researchers about the quantities and distribution of phytoplankton and other materials, providing clues as to how the world ocean is changing. NASA s Coastal Zone Color Scanner, launched in 1978, was the first ocean color instrument flown on a spacecraft. Since then, the Agency s ocean color research capabilities have become increasingly sophisticated with the launch of the SeaWiFS instrument in 1997 and the twin MODIS instruments carried into orbit on NASA s Terra (1999) and Aqua (2002) satellites. The technology provides sweeping, global information on ocean color on a scale unattainable by any other means. One issue that arises from

  1. Abrasive supply for ancient Egypt revealed

    International Nuclear Information System (INIS)

    In the framework of the major research scheme 'Synchronization of Civilizations in the Eastern Mediterranean Region in the 2nd Millennium B.C' instrumental neutron activation analysis (INAA) was used to determine 30 elements in pumice from archaeological excavations to reveal their specific volcanic origin. In ancient time, the widespread pumiceous products of several eruptions in the Aegean region have been used as abrasive tools and were therefore popular trade objects. The correlation of such archaeological findings to a specific eruption of known age would therefore allow to certify a maximum age of the respective stratum ('dating by first appearance'). Pumices from the Aegean region can easily be distinguished by their trace element distribution patterns. This has been shown by previous studies of the group. The elements Al, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mn, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, Ti, U, V, Yb, Zr and Zn were determined in 16 samples of pumice lumps from excavations in Tell-el-Dab'a and Tell-el-Herr (Egypt). Two irradiation cycles and five measurement runs were applied. To show the accuracy of the results obtained, typical samples of the most important pumice sources in the Aegean region, particularly from Milos, Nisyros, Kos and Thera were analyzed together with the Egyptian samples of unknown origin. A reliable identification of the samples is achieved by comparing these results to the database compiled in previous studies. The geographical positions of these islands are shown. Within the error range, most of the elements determined in typical representatives of Milos, Nisyros, Kos and Santorini were in perfect agreement with values from the literature. On the basis of the Cluster graphics presented, it is possible to relate unknown pumice to its primary source, just by comparing the relation of a few elements, like Ta-Eu and Th-Hf. One concludes that all samples except one can be related to the Minoan eruption of Thera

  2. Chandra Data Reveal Rapidly Whirling Black Holes

    Science.gov (United States)

    2008-01-01

    A new study using results from NASA's Chandra X-ray Observatory provides one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly. The whirling of these giant black holes drives powerful jets that pump huge amounts of energy into their environment and affects galaxy growth. A team of scientists compared leading theories of jets produced by rotating supermassive black holes with Chandra data. A sampling of nine giant galaxies that exhibit large disturbances in their gaseous atmospheres showed that the central black holes in these galaxies must be spinning at near their maximum rates. People Who Read This Also Read... NASA’s Swift Satellite Catches First Supernova in The Act of Exploding Black Holes Have Simple Feeding Habits Jet Power and Black Hole Assortment Revealed in New Chandra Image Erratic Black Hole Regulates Itself "We think these monster black holes are spinning close to the limit set by Einstein's theory of relativity, which means that they can drag material around them at close to the speed of light," said Rodrigo Nemmen, a visiting graduate student at Penn State University, and lead author of a paper on the new results presented at American Astronomical Society in Austin, Texas. The research reinforces other, less direct methods previously used which have indicated that some stellar and supermassive black holes are spinning rapidly. According to Einstein's theory, a rapidly spinning black hole makes space itself rotate. This effect, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic, high-speed jet. Computer simulations by other authors have suggested that black holes may acquire their rapid spins when galaxies merge, and through the accretion of gas from their surroundings. "Extremely fast spin might be very common for large

  3. Note on generated choice and axioms of revealed preference

    OpenAIRE

    Magyarkuti, Gyula

    2000-01-01

    In this article, we study the axiomatic foundations of revealed preference theory. Let P denote the strict and R the weak revealed preference, respectively. The purpose of the paper is to show that weak, strong, and Hansson's axioms of revealed preference can be given as identities using the generated choices with respect to P and R in terms of maximality and in terms of greatestness.

  4. Revealed Preference Tests using Supermarket Data: the Money Pump

    OpenAIRE

    Echenique, Federico; Lee, Sangmok; Shum, Matthew

    2010-01-01

    We use a money pump argument to measure deviations from the revealed preference axioms. Using a panel data set of food expenditures, we find a large number of violations of the weak axiom of revealed preference. The money pump costs are small, which indicate that the violations of revealed preference are not severe. While most households' behavior deviates from rationality, by our measure they are close to being rational.

  5. Genome-Wide Scan Reveals Mutation Associated with Melanoma

    Science.gov (United States)

    ... 1999 Spotlight on Research 2012 July 2012 (historical) Genome-Wide Scan Reveals Mutation Associated with Melanoma A ... out to see if a technology called whole genome sequencing would help them find other genetic risk ...

  6. [An original revealing mode of sarcoidosis: Sweet's syndrome].

    Science.gov (United States)

    Bricha, Myriem; Sqalli, Fatimazzahra; Hammi, Sanae; Bourkadi, Jamal Eddine

    2016-01-01

    Sweet's syndrome is a neutrophilic dermatosis which usually presents as an idiopathic disorder. The combination of Sweet's syndrome and sarcoidosis is rare. We report the clinical case of a Sweet's syndrome revealing sarcoidosis. PMID:27279949

  7. Revealing ecological networks using Bayesian network inference algorithms.

    Science.gov (United States)

    Milns, Isobel; Beale, Colin M; Smith, V Anne

    2010-07-01

    Understanding functional relationships within ecological networks can help reveal keys to ecosystem stability or fragility. Revealing these relationships is complicated by the difficulties of isolating variables or performing experimental manipulations within a natural ecosystem, and thus inferences are often made by matching models to observational data. Such models, however, require assumptions-or detailed measurements-of parameters such as birth and death rate, encounter frequency, territorial exclusion, and predation success. Here, we evaluate the use of a Bayesian network inference algorithm, which can reveal ecological networks based upon species and habitat abundance alone. We test the algorithm's performance and applicability on observational data of avian communities and habitat in the Peak District National Park, United Kingdom. The resulting networks correctly reveal known relationships among habitat types and known interspecific relationships. In addition, the networks produced novel insights into ecosystem structure and identified key species with high connectivity. Thus, Bayesian networks show potential for becoming a valuable tool in ecosystem analysis. PMID:20715607

  8. Facial cellulitis revealing choreo-acanthocytosis: a case report

    OpenAIRE

    Samia, Younes; Yosra, Cherif; Foued, Bellazreg; Mouna, Aissi; Olfa, Berriche; Jihed, Souissi; Hammadi, Braham; Mahbouba, Frih-Ayed; Amel, Letaief; Habib, Sfar Mohamed

    2014-01-01

    We report a 62 year-old-man with facial cellulitis revealing choreo-acanthocytosis (ChAc). He showed chorea that started 20 years ago. The orofacial dyskinisia with tongue and cheek biting resulted in facial cellulitis. The peripheral blood smear revealed acanthocytosis of 25%. The overall of chorea, orofacial dyskinetic disorder, peripheral neuropathy, disturbed behavior, acanthocytosis and the atrophy of caudate nuclei was suggestive of a diagnosis of ChAc. To our knowledge no similar cases...

  9. The Microbiome of Brazilian Mangrove Sediments as Revealed by Metagenomics

    OpenAIRE

    Fernando Dini Andreote; Diego Javier Jiménez; Diego Chaves; Armando Cavalcante Franco Dias; Danice Mazzer Luvizotto; Francisco Dini-Andreote; Cristiane Cipola Fasanella; Maryeimy Varon Lopez; Sandra Baena; Rodrigo Gouvêa Taketani; Itamar Soares de Melo

    2012-01-01

    Here we embark in a deep metagenomic survey that revealed the taxonomic and potential metabolic pathways aspects of mangrove sediment microbiology. The extraction of DNA from sediment samples and the direct application of pyrosequencing resulted in approximately 215 Mb of data from four distinct mangrove areas (BrMgv01 to 04) in Brazil. The taxonomic approaches applied revealed the dominance of Deltaproteobacteria and Gammaproteobacteria in the samples. Paired statistical analysis showed high...

  10. Opposite influence of perceptual memory on initial and prolonged perception of sensory ambiguity.

    Directory of Open Access Journals (Sweden)

    Maartje Cathelijne de Jong

    Full Text Available Observers continually make unconscious inferences about the state of the world based on ambiguous sensory information. This process of perceptual decision-making may be optimized by learning from experience. We investigated the influence of previous perceptual experience on the interpretation of ambiguous visual information. Observers were pre-exposed to a perceptually stabilized sequence of an ambiguous structure-from-motion stimulus by means of intermittent presentation. At the subsequent re-appearance of the same ambiguous stimulus perception was initially biased toward the previously stabilized perceptual interpretation. However, prolonged viewing revealed a bias toward the alternative perceptual interpretation. The prevalence of the alternative percept during ongoing viewing was largely due to increased durations of this percept, as there was no reliable decrease in the durations of the pre-exposed percept. Moreover, the duration of the alternative percept was modulated by the specific characteristics of the pre-exposure, whereas the durations of the pre-exposed percept were not. The increase in duration of the alternative percept was larger when the pre-exposure had lasted longer and was larger after ambiguous pre-exposure than after unambiguous pre-exposure. Using a binocular rivalry stimulus we found analogous perceptual biases, while pre-exposure did not affect eye-bias. We conclude that previously perceived interpretations dominate at the onset of ambiguous sensory information, whereas alternative interpretations dominate prolonged viewing. Thus, at first instance ambiguous information seems to be judged using familiar percepts, while re-evaluation later on allows for alternative interpretations.

  11. 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.

  12. Learning of monocular information facilitates breakthrough to awareness during interocular suppression.

    Science.gov (United States)

    Mastropasqua, Tommaso; Tse, Peter U; Turatto, Massimo

    2015-04-01

    Continuous flash suppression (CFS) is a potent method of inducing binocular rivalry, wherein a rapid succession of high-contrast images presented to one eye effectively blocks from awareness a low-contrast image presented to the other eye. Here we addressed whether the contents of the suppressed image can break through to awareness with extended CFS exposure. On 2/3 of the trials, we presented a faint bar (the target) to the nondominant eye while a high-contrast flickering Mondrian (the mask) was displayed to the dominant eye. Participants were first asked to report whether the target had broken through the CFS mask. Furthermore, on target-present trials, the participants were then asked to guess whether the target had appeared above or below the fixation point. In Experiment 1, the target was presented with a fixed orientation for four blocks of trials, whereas in the fifth block, the target could also have the orthogonal orientation. In Experiment 2, the target was always presented with a fixed orientation, but in the fifth block, unbeknownst to participants, the target and the mask were swapped across the eyes. We found that awareness of the target rapidly improved with training in both experiments. However, whereas Experiment 1 revealed that the improvement largely generalized across stimulus orientations, Experiment 2 showed that the effect of practice was eye-specific. The results suggest that increased breakthrough with training was due to a monocular form of learning. Finally, a control experiment was conducted to exclude the possibility that the monocular learning we reported could have been due to sensory adaptation caused by the masks. PMID:25720759

  13. Serial order learning of subliminal visual stimuli: evidence of multistage learning

    Directory of Open Access Journals (Sweden)

    Kaede eKido

    2015-02-01

    Full Text Available It is well-known that statistical learning of visual symbol sequences occurs implicitly (Kim et al., 2009. Here, we examined whether people can learn the serial order of the visual symbols when they cannot perceive them. During the familiarization phase, triplets or quadruplets of novel symbols were presented to one of the eyes under continuous flash suppression (CFS. Perception of the symbols was completely suppressed by the flash patterns presented to the other eye (binocular rivalry. In the test phase, the detection latency was faster for the symbols located later in the triplets or the quadruplets. These results indicate that serial order learning occurs even when the participants cannot perceive the stimuli. We also found that the detection became slower for the last item of the triplets or the quadruplets. This phenomenon occurred only when the participants were familiarized to the symbols under CFS, suggesting that the following symbols interfered with the processing for the target symbol when conscious perception was suppressed. We further examined the nature of the interference, and found that the interference occurred only when the following symbol was not fixed. This result suggests that serial order learning under binocular rivalry is restricted to the fixed order sequence. Statistical learning for the transition probability of the symbols might not occur when participants cannot perceive the symbols. We confirmed this hypothesis by conducting another experiment in which transition probability of the symbol sequence was manipulated.

  14. [Ovarian torsion revealing an ovarian cavernous hemangioma in a child].

    Science.gov (United States)

    M'pemba Loufoua-Lemay, A-B; Peko, J-F; Mbongo, J-A; Mokoko, J-C; Nzingoula, S

    2003-11-01

    The authors report one case of cavernous hemangioma of the left ovary, which was revealed by ovarian torsion. Such benign tumors of the blood vessels are rare in ovaries during childhood. This hemangioma was observed in a 13-year-old patient, who presented with abdominal and pelvic pain and vomiting. The pelvic mass was noted and sonography revealed a cystic tumor. An annexectomia was realized. Histology showed narcotized ovary cells, with an increased number of vascular channels composed of thin walled vessels, whose wall consisted of an endothelium. This aspect evoked a cavernous hemangioma of the ovary. PMID:14613693

  15. Adaptation to High Ethanol Reveals Complex Evolutionary Pathways

    Science.gov (United States)

    Das, Anupam; Espinosa-Cantú, Adriana; De Maeyer, Dries; Arslan, Ahmed; Van Pee, Michiel; van der Zande, Elisa; Meert, Wim; Yang, Yudi; Zhu, Bo; Marchal, Kathleen; DeLuna, Alexander; Van Noort, Vera; Jelier, Rob; Verstrepen, Kevin J.

    2015-01-01

    Tolerance to high levels of ethanol is an ecologically and industrially relevant phenotype of microbes, but the molecular mechanisms underlying this complex trait remain largely unknown. Here, we use long-term experimental evolution of isogenic yeast populations of different initial ploidy to study adaptation to increasing levels of ethanol. Whole-genome sequencing of more than 30 evolved populations and over 100 adapted clones isolated throughout this two-year evolution experiment revealed how a complex interplay of de novo single nucleotide mutations, copy number variation, ploidy changes, mutator phenotypes, and clonal interference led to a significant increase in ethanol tolerance. Although the specific mutations differ between different evolved lineages, application of a novel computational pipeline, PheNetic, revealed that many mutations target functional modules involved in stress response, cell cycle regulation, DNA repair and respiration. Measuring the fitness effects of selected mutations introduced in non-evolved ethanol-sensitive cells revealed several adaptive mutations that had previously not been implicated in ethanol tolerance, including mutations in PRT1, VPS70 and MEX67. Interestingly, variation in VPS70 was recently identified as a QTL for ethanol tolerance in an industrial bio-ethanol strain. Taken together, our results show how, in contrast to adaptation to some other stresses, adaptation to a continuous complex and severe stress involves interplay of different evolutionary mechanisms. In addition, our study reveals functional modules involved in ethanol resistance and identifies several mutations that could help to improve the ethanol tolerance of industrial yeasts. PMID:26545090

  16. Goodness-of-Fit for Revealed Preference Tests

    OpenAIRE

    Hal R. Varian

    1994-01-01

    I describe a goodness-of-fit measure for revealed preference tests. This index can be used to measure the degree to which an economic agent violates the model of utility maximization. I calculate the violation indices for a 38 consumers and find that the observed choice behavior is very close to optimizing behavior.

  17. When Values and Behaviors Conflict: Immigrant BSW Students' Experiences Revealed

    Science.gov (United States)

    Calderwood, Kimberly; Harper, Kim; Ball, Kellie; Liang, David

    2009-01-01

    This qualitative study reveals the discomfort seven immigrant bachelor of social work students reported experiencing when the behaviors expected of them as Canadian social workers conflicted with their fundamental family values. Behaviorally, participants had assimilated to Canadian and to social work cultures; however, the values they held from…

  18. [Ulcerated duodenitis revealing Henoch-Schönlein purpura].

    Science.gov (United States)

    Marting, A; Defrance, P; Wain, E; Van Severen, M; Deflandre, J

    2015-01-01

    Inflammation and duodenal ulcers can meet many etiologies. We report the case of a young adult with an ulcerated duodenitis revealing Henoch-Schönlein purpura. The abdominal symptoms preceded the emergence of the classical cutaneous signs of the disease. PMID:26376566

  19. MRI reveals reversible lesions resembling posterior reversible encephalopathy in porphyria

    International Nuclear Information System (INIS)

    We report a 20-year-old woman who had an attack of acute intermittent porphyria with seizures, hallucinations, autonomic and somatic neuropathy. T2-weighted MRI revealed multiple lesions which were no longer visible 3 months later. We suggest a similar mechanism to posterior reversible encephalopathy underlying cerebral symptoms in porphyria. (orig.)

  20. MRI reveals reversible lesions resembling posterior reversible encephalopathy in porphyria

    Energy Technology Data Exchange (ETDEWEB)

    Celik, M. [Huesrev Gerede c, 128/4 Tesvikiye, 80690 Istanbul (Turkey); Department of Neurology, Sisli Etfal Education and Research Hospital, Sisli Etfal S., Sisli, Istanbul (Turkey); Forta, H.; Babacan, G. [Department of Neurology, Sisli Etfal Education and Research Hospital, Sisli Etfal S., Sisli, Istanbul (Turkey); Dalkilic, Tuerker [Department of Neurosurgery, Sisli Etfal Education and Research Hospital, Sisli Etfal S., Sisli, Istanbul (Turkey)

    2002-10-01

    We report a 20-year-old woman who had an attack of acute intermittent porphyria with seizures, hallucinations, autonomic and somatic neuropathy. T2-weighted MRI revealed multiple lesions which were no longer visible 3 months later. We suggest a similar mechanism to posterior reversible encephalopathy underlying cerebral symptoms in porphyria. (orig.)