Asymmetric Matching Research Articles

Electrochemiluminescence Sensor Based on CeO2 Nanocrystalline for Hg2+ Detection in Environmental Samples.

The excessive concentration of heavy-metal mercury ions (Hg2+) in the environment seriously affects the ecological environment and even threatens human health. Therefore, it is necessary to develop rapid and low-cost determination methods to achieve trace detection of Hg2+. In this paper, an Electrochemiluminescence (ECL) sensing platform using a functionalized rare-earth material (cerium oxide, CeO2) as the luminescent unit and an aptamer as a capture unit was designed and constructed. Using the specific asymmetric matching between Hg2+ and thymine (T) base pairs in the deoxyribonucleic acid (DNA) single strand, the "T-Hg-T" structure was formed to change the ECL signal, leading to a direct and sensitive response to Hg2+. The results show a good linear relationship between the concentration and the response signal within the range of 10 pM-100 µM for Hg2+, with a detection limit as low as 0.35 pM. In addition, the ECL probe exhibits a stable ECL performance and excellent specificity for identifying target Hg2+. It was then successfully used for spiked recovery tests of actual samples in the environment. The analytical method solves the problem of poor Hg2+ recognition specificity, provides a new idea for the efficient and low-cost detection of heavy-metal pollutant Hg2+ in the environment, and broadens the prospects for the development and application of rare-earth materials.

Revisiting the Asymmetric Matching Pennies Contradiction in China.

The asymmetric matching pennies contradiction posits that contrary to the prediction of mixed-strategy Nash equilibrium, experimental subjects' choices are, in practice, based heavily on the magnitudes of their own payoffs. Own-payoff effects are robustly confirmed in the literature. Closely following the experimental setups in the literature which support the contradiction, we conduct a series of asymmetric matching pennies games in China, hypothesizing play which is closer to equilibrium frequencies than previously found. Contrary to previous experiments which were conducted in the United States, we find that there are essentially no own-payoff effects among Row players who face large payoff asymmetry. In a Quantal Response Equilibrium framework allowing for altruism or spite, the behavior of our subjects corresponded to a positive spite parameter, whereas the results of previous studies corresponded to altruism. Our results may be consistent with recent psychology literature that finds people from collectivist cultures are substantially more adept at taking the perspective of others compared with people from individualist cultures, a feature of the reasoning needed to obtain mixed-strategy equilibrium.

Asymmetric matching of color and gloss across different lighting environments

Asymmetric matching of color and gloss across different lighting environments

A new corresponding color dataset covering a wide luminance range under high dynamic range viewing condition

An experiment was carried out to investigate the change of color appearance for 13 surface stimuli viewed under a wide range of illuminance levels (15-32000 lux) using asymmetrical matching method. Addition to the above, in the visual field, observers viewed colours in a dark (10 lux) and a bright (200000 lux) illuminance level at the same time to simulate HDR viewing condition. The results were used to understand the relationship between the color changes under HDR conditions, to generate a corresponding color dataset and to verify color appearance model, such as CIECAM16.

Dynamic asymmetric assignment problem in open multi-agent systems

The purpose of the work is to develop models and algorithms for optimizing matching in dynamically generated graphs of asymmetric relations in coordinated open systems of interacting agents with centralized and collective control. The dynamic asymmetric matching optimization problem arises here as a result of a compromise approximation of the mapping of the dynamic programming method onto a stream of known open assignment problems or several traveling salesmen. However, the branching alternatives presented in this way for independent tasks do not take into account the interdependence of real relationships between agents and their tasks, including their relationship to time. Ignoring the dependence of branching alternatives leads to a delay in the moment or to a loss in the quality of assignment of tasks to coordinated agents. The main idea of the proposed implementation of the principle known for effective control is to postpone the moment the final decision is made to the latest moment, taking into account the susceptibility of the system to local changes in state variables. The interdependence of states is revealed on the basis of the analysis of the correspondence of the graph of the current matching with the optimal solution on the subgraph of perfect matching. The transition between states is implemented by the incremental version of the reoptimization algorithm for solving linear problems of assigning the shortest replenishing path using the method. The space of search states is a dynamically generated bipartite sparse graph of alternatives for a combination of agents and tasks, represented by a list of arcs. To highlight the sets of changed arcs, it is proposed to supplement the weight of the arcs with the boundaries of the stability intervals of the solution, optionally formed in the background. By default, the weight of the modified arc matches the boundary of the stability interval. On each correction cycle of the lists of agents, tasks, and their associations, subsets of elements are selected for which reconsideration of matching is required. An enhanced condition for the selection of such elements is to go beyond the boundaries of the stability interval. In this case, the asymmetry of the assignment problem is taken into account by choosing the adjacency structure for the fraction of the graph with a minimum of vertices. As a result, the reaction time of procedures for solving the assignment problem is reduced by an order of magnitude.

Is CIELAB one space or many?

AbstractModels in colour engineering can have implicit customary usage, outside of whose parameters one is not supposed to venture. CIELAB is one such model: although able to accommodate a prediction of asymmetric matches, CIELAB is used in practice to compare colours only for a given illuminant/observer condition. Should we therefore deem CIELAB to be an infinity of spaces, one for each illuminant/observer combination? This question has its roots in an oddity of CIELAB’s chromatic‐adaptation model. A chromatic‐adaptation oddity also entered CIE models that emerged after CIELAB, and leads to a similarly perplexing question.

Chromatic fading following complete adaptation to unique hues.

Profound vision loss occurs after prolonged exposure to an unchanging featureless visual environment. The effect is sometimes called visual fade. Here we investigate this phenomenon in the color domain using two different experiments. In the first experiment we determine the time needed for a colored background to appear achromatic. Four backgrounds were tested. Each represented the observers’ four unique hues. This adaptation time was compared with time to recover after adaptation Hue shifts at the end of the adaptation period were also measured. There were wide individual differences in adaptation times and recovery times. Overall recovery was faster than adaptation (p < 0.02). There were minimal shifts in hue. In the second experiment the changes in saturation (Munsell chroma) and lightness (Munsell value) of the background were monitored at six time intervals during the adapting process. Again asymmetric matching with Munsell samples was used. There were two distinct components to both the adaptation and recovery phases; one fast with time constant <1s, the other slow with time constant between 40 and 160s.The experiments show that the special case of visual fade involving color represents the sensory basis for many color-related effects involving adaptation.

Toward reliable measurements of perceptual scales in multiple contexts

A central question in psychophysical research is how perceptual differences between stimuli translate into physical differences and vice versa. Characterizing such a psychophysical scale would reveal how a stimulus is converted into a perceptual event, particularly under changes in viewing conditions (e.g., illumination). Various methods exist to derive perceptual scales, but in practice, scale estimation is often bypassed by assessing appearance matches. Matches, however, only reflect the underlying perceptual scales but do not reveal them directly. Two recently developed methods, MLDS (Maximum Likelihood Difference Scaling) and MLCM (Maximum Likelihood Conjoint Measurement), promise to reliably estimate perceptual scales. Here we compared both methods in their ability to estimate perceptual scales across context changes in the domain of lightness perception. In simulations, we adopted a lightness constant, a contrast, and a luminance-based observer model to generate differential patterns of perceptual scales. MLCM correctly recovered all models. MLDS correctly recovered only the lightness constant observer model. We also empirically probed both methods with two types of stimuli: (a) variegated checkerboards that support lightness constancy and (b) center-surround stimuli that do not support lightness constancy. Consistent with the simulations, MLDS and MLCM provided similar scale estimates in the first case and divergent estimates in the second. In addition, scales from MLCM–and not from MLDS–accurately predicted asymmetric matches for both types of stimuli. Taking experimental and simulation results together, MLCM seems more apt to provide a valid estimate of the perceptual scales underlying judgments of lightness across viewing conditions.

Color and brightness constancies depend reciprocally on saturation

Color and brightness constancies may not be independent, since increasing a sample saturation should decrease the demand on the color constancy and increase that on the brightness constancy [Color Res. Appl.43, 630 (2018)CREADU0361-231710.1002/col.22227]. We tested this claim using color and brightness constancy data from Foster et al. [Vis. Res.41, 285 (2001)VISRAM0042-698910.1016/S0042-6989(00)00239-X], whose observers made side-by-side and successive comparisons of central patches ("asymmetric matches") presented in pairs of identical Mondrian displays with simulated illuminants of 25000 K and 6700 K daylights. Saturations (CIE "chroma") of the central patches varied from 0.007 to 0.092. For most observers (as in a toy Gaussian model of the surface reflectance spectra), increasing saturation reduced color constancy and increased brightness constancy.

Stable matchings in high dimensions via the Poisson-weighted infinite tree

Nous considérons l’appariement stable de deux processus de Poisson indépendants dans $\mathbb{R}^{d}$, sous une contrainte asymmetrique sur les couleurs. Un point bleu ne peut être apparié qu’à un point rouge, tandis qu’un point rouge peut être apparié soit à un point rouge soit à un point bleu. On ne sait pas s’il existe un choix d’intensités des processus bleu et rouge tel que tous les points sont appariés. Nous démontrons que pour toutes intensités fixes, il y a des points bleus non-appariés en dimension suffisamment elevée. En effet, si le rapport de l’intensité des points rouges à l’intensité des points bleus est $\rho $, l’intensité des points bleus non-appariés tend vers $e^{-\rho }/(1+\rho )$ quand $d\to \infty $. On établit aussi des résultats analogues pour certaines variantes à multiples couleurs. La preuve utilise un modèle d’appariement stable sur l’arbre infini pondéré de Poisson (PWIT), qui peut être analysé par des équations différentielles. Le PWIT a été utilisé dans de nombreux contextes comme limite d’échelle pour des modèles impliquant des graphes complets pondérés de variables aléatoires indépendants, mais à notre connaissance, celle-ci est la première présentation d’une application rigoureuse à l’espace euclidien en haute dimension. Finalement, on analyse le problème d’appariement asymétrique sous une métrique hiérarchique, et on démontre qu’il existe des points non-appariés pour tout choix d’intensités.

Discriminative Multi-view Privileged Information Learning for Image Re-ranking.

Conventional multi-view re-ranking methods usually perform asymmetrical matching between the region of interest (ROI) in the query image and the whole target image for similarity computation. Due to the inconsistency in the visual appearance, this practice tends to degrade the retrieval accuracy particularly when the image ROI, which is usually interpreted as the image objectness, accounts for a smaller region in the image. Since Privileged Information (PI), which can be viewed as the image prior, is able to characterize well the image objectness, we are aiming at leveraging PI for further improving the performance of multi-view re-ranking in this paper. Towards this end, we propose a discriminative multi-view re-ranking approach in which both the original global image visual contents and the local auxiliary PI features are simultaneously integrated into a unified training framework for generating the latent subspaces with sufficient discriminating power. For the on-the-fly re-ranking, since the multi-view PI features are unavailable, we only project the original multi-view image representations onto the latent subspace, and thus the re-ranking can be achieved by computing and sorting the distances from the multi-view embeddings to the separating hyperplane. Extensive experimental evaluations on the two public benchmarks, Oxford5k and Paris6k, reveal that our approach provides further performance boost for accurate image re-ranking, whilst the comparative study demonstrates the advantage of our method against other multi-view re-ranking methods.

A neural field model for color perception unifying assimilation and contrast.

We address the question of color-space interactions in the brain, by proposing a neural field model of color perception with spatial context for the visual area V1 of the cortex. Our framework reconciles two opposing perceptual phenomena, known as simultaneous contrast and chromatic assimilation. They have been previously shown to act synergistically, so that at some point in an image, the color seems perceptually more similar to that of adjacent neighbors, while being more dissimilar from that of remote ones. Thus, their combined effects are enhanced in the presence of a spatial pattern, and can be measured as larger shifts in color matching experiments. Our model supposes a hypercolumnar structure coding for colors in V1, and relies on the notion of color opponency introduced by Hering. The connectivity kernel of the neural field exploits the balance between attraction and repulsion in color and physical spaces, so as to reproduce the sign reversal in the influence of neighboring points. The color sensation at a point, defined from a steady state of the neural activities, is then extracted as a nonlinear percept conveyed by an assembly of neurons. It connects the cortical and perceptual levels, because we describe the search for a color match in asymmetric matching experiments as a mathematical projection on color sensations. We validate our color neural field alongside this color matching framework, by performing a multi-parameter regression to data produced by psychophysicists and ourselves. All the results show that we are able to explain the nonlinear behavior of shifts observed along one or two dimensions in color space, which cannot be done using a simple linear model.

Perceptual dimensions underlying lightness perception in homogeneous center-surround displays.

Lightness judgments of targets embedded in a homogeneous surround exhibit abrupt steps in perceived lightness at points at which the targets transition from being increments to decrements. This "crispening effect" and the general difficulty of matching low-contrast targets embedded in homogeneous surrounds suggest that a second perceptual dimension in addition to lightness may contribute to the appearance of test patches in these displays. The present study explicitly tested whether two dimensions (lightness and transmittance) could lead to more satisfactory matches than lightness alone in an asymmetric matching task. We also examined whether transmittance matches were more strongly associated with task instructions that had observers match perceived transparency or the perceived edge contrast of the target relative to the surround. We found that matching target lightness in a homogeneous display to that in a textured or rocky display required varying both lightness and transmittance of the test patch on the textured display to obtain the most satisfactory matches. However, observers primarily varied transmittance when instructed to match the perceived contrast of targets against homogeneous surrounds, but not when instructed to match the amount of transparency perceived in the displays. The results suggest that perceived target-surround edge contrast differs between homogeneous and textured displays. Varying the midlevel property of transparency in textured displays provides a natural means for equating both target lightness and the unique appearance of the edge contrast in homogeneous displays.

Evaluation of color prediction methods in terms of least-dissimilar asymmetric matching

The performance of Color Prediction Methods CAT02, KSM2, Waypoint, Best Linear, MMV center, and relit color signal are compared in terms of how well they explain Logvinenko &amp; Tokunaga [1] asymmetric color matching results. In their experiment, given a Munsell paper under a test illuminant, 4 observers were asked to determine (3 repeats) which of 22 other Munsell papers made the least-dissimilar match under a match illuminant. Given this data, we address the following four questions. Question 1: Are observers choosing the original Munsell paper under the match illuminant? If they are, then the average (12 matches) color signal (cone response triple or XYZ) made under a given illuminant condition should correspond to that of the Munsell paper's color signal under the match illuminant. Computation shows that in 274 of the 400 cases, the relit color signal is close to the mean color signal of the matches. Question 2: How do algorithm predictions compare to the average observer prediction of the actual color signal of the relit paper? The Wilcoxon signed-rank test shows that KSM2, Waypoint, and Best Linear perform equally, and that both slightly outperform the observer average, which, in turn, significantly outperforms CAT02, and MMV (metamer mismatch volume) center. Question 3: Which method most closely predicts the observer average? We found that the color signal of the relit reflectance is a better predictor of the average observer than Best Linear, which in turn is marginally better than Wpt and KSM2, both of which outperform CATO2 and MMV center. Question 4: Do the observers agree with one another? Using a leave-one-observer-out comparison shows that individual observers predict the average matches of the remaining observers somewhat better than the relit color signal, which in turn slightly outperforms Best Linear, Wpt and KSM2, which then all significantly outperform CATO2 and MMV center.

Uncertainty of sensory signal explains variation of color constancy.

Color constancy is the ability to recognize the color of an object (or more generally of a surface) under different illuminations. Without color constancy, surface color as a perceptual attribute would not be meaningful in the visual environment, where illumination changes all the time. Nevertheless, it is not obvious how color constancy is possible in the light of metamer mismatching. Surfaces that produce exactly the same sensory color signal under one illumination (metamerism) may produce utterly different sensory signals under another illumination (metamer mismatching). Here we show that this phenomenon explains to a large extent the variation of color constancy across different colors. For this purpose, color constancy was measured for different colors in an asymmetric matching task with photorealistic images. Color constancy performance was strongly correlated to the size of metamer mismatch volumes, which describe the uncertainty of the sensory signal due to metamer mismatching for a given color. The higher the uncertainty of the sensory signal, the lower the observers' color constancy. At the same time, sensory singularities, color categories, and cone ratios did not affect color constancy. The present findings do not only provide considerable insight into the determinants of color constancy, they also show that metamer mismatch volumes must be taken into account when investigating color as a perceptual property of objects and surfaces.

The nature of instructional effects in color constancy.

The instructions subjects receive can have a large effect on experimentally measured color constancy, but the nature of these effects and how their existence should inform our understanding of color perception remains unclear. We used a factorial design to measure how instructional effects on constancy vary with experimental task and stimulus set. In each of 2 experiments, we employed both a classic adjustment-based asymmetric matching task and a novel color selection task. Four groups of naive subjects were instructed to make adjustments/selections based on (a) color (neutral instructions); (b) the light reaching the eye (physical spectrum instructions); (c) the actual surface reflectance of an object (objective reflectance instructions); or (d) the apparent surface reflectance of an object (apparent reflectance instructions). Across the 2 experiments we varied the naturalness of the stimuli. We find clear interactions between instructions, task, and stimuli. With simplified stimuli (Experiment 1), instructional effects were large and the data revealed 2 instruction-dependent patterns. In 1 (neutral and physical spectrum instructions) constancy was low, intersubject variability was also low, and adjustment-based and selection-based constancy were in agreement. In the other (reflectance instructions) constancy was high, intersubject variability was large, adjustment-based constancy deviated from selection-based constancy and for some subjects selection-based constancy increased across sessions. Similar patterns held for naturalistic stimuli (Experiment 2), although instructional effects were smaller. We interpret these 2 patterns as signatures of distinct task strategies-1 is perceptual, with judgments based primarily on the perceptual representation of color; the other involves explicit instruction-driven reasoning. (PsycINFO Database Record

Stimulus size dependence of hue changes induced by chromatic surrounds.

A chromatic surround induces a change in the perceived hue of a stimulus. This shift in hue depends on the chromatic difference between the stimulus and the surround. We investigated how chromatic induction varies with stimulus size and whether the size dependence depends on the surround hue. Subjects performed asymmetric matching of color stimuli with different sizes in surrounds of different chromaticities. Generally, induced hue shifts decreased with increasing stimulus size. This decrease was quantitatively different for different surround hues. However, when size effects were normalized to an overall induction strength, the chromatic specificity was largely reduced. The separability of inducer chromaticity and stimulus size suggests that these effects are mediated by different neural mechanisms.

Changes in unique hues induced by chromatic surrounds.

A chromatic surround can have a strong influence on the perceived hue of a stimulus. We investigated whether chromatic induction has similar effects on the perception of colors that appear pure and unmixed (unique red, green, blue, and yellow) as on other colors. Subjects performed unique hue settings of stimuli in isoluminant surrounds of different chromaticities. Compared with the settings in a neutral gray surround, unique hue settings altered systematically with chromatic surrounds. The amount of induced hue shift depended on the difference between stimulus and surround hues, and was similar for unique hue settings as for settings of nonunique hues. Intraindividual variability in unique hue settings was roughly twice as high as for settings obtained in asymmetric matching experiments, which may reflect the presence of a reference stimulus in the matching task. Variabilities were also larger with chromatic surrounds than with neutral gray surrounds, for both unique hue settings and matching of nonunique hues. The results suggest that the neural representations underlying unique hue percepts are influenced by the same neural processing mechanisms as the percepts of other colors.

Contrast adaptation to luminance and brightness modulations.

Perceptual brightness and color contrast decrease after seeing a light temporally modulating along a certain direction in a color space, a phenomenon known as contrast adaptation. We investigated whether contrast adaptation along the luminance direction arises from modulation of luminance signals or apparent brightness signals. The stimulus consisted of two circles on a gray background presented on a CRT monitor. In the adaptation phase, the luminance and chromaticity of one circle were temporally modulated, while the other circle was kept at a constant luminance and color metameric with an equal-energy white. We employed two types of temporal modulations, namely, in luminance and brightness. Chromaticity was sinusoidally modulated along the L-M axis, leading to dissociation between luminance and brightness (the Helmholtz-Kohlrausch effect). In addition, luminance modulation was minimized in the brightness modulation, while brightness modulation was minimized in the luminance modulation. In the test phase, an asymmetric matching method was used to measure the magnitude of contrast adaptation for both modulations. Our results showed that, although contrast adaptation along the luminance direction occurred for both modulations, contrast adaptation for luminance modulation was significantly stronger than that for the brightness modulation regardless of the temporal frequency of the adaptation modulation. These results suggest that luminance modulation is more influential in contrast adaptation than brightness modulation.

Graphene Transistor-Based Active Balun Architectures

While different RF functionalities, such as an amplifier or a mixer, have been designed using the graphene FET (GFET) devices, the balun circuit has not been explored. In this paper, two innovative active balun architectures are presented taking advantage of the GFET’s unique symmetrical and ambipolar behavior, respectively. The symmetry-based active balun circuit is realized using an advanced SiC-based GFET RF technology. After circuit design and optimization using a large signal GFET compact model, the circuit has been fabricated and characterized. Measurement results confirm its excellent functionality. Circuit simulation shows that the second architecture exploring the GFETs ambipolar behavior gives equivalent results compared with the first architecture. Both topologies avoid asymmetric impedance matching and result in the accurate amplitude and phase balance of the balun.