No-Reference Quality Assessment for 3D Synthesized Images Based on Visual-Entropy-Guided Multi-Layer Features Analysis

Multiview video plus depth is one of the mainstream representations of 3D scenes in emerging free viewpoint video, which generates virtual 3D synthesized images through a depth-image-based-rendering (DIBR) technique. However, the inaccuracy of depth maps and imperfect DIBR techniques result in different geometric distortions that seriously deteriorate the users’ visual perception. An effective 3D synthesized image quality assessment (IQA) metric can simulate human visual perception and determine the application feasibility of the synthesized content. In this paper, a no-reference IQA metric based on visual-entropy-guided multi-layer features analysis for 3D synthesized images is proposed. According to the energy entropy, the geometric distortions are divided into two visual attention layers, namely, bottom-up layer and top-down layer. The feature of salient distortion is measured by regional proportion plus transition threshold on a bottom-up layer. In parallel, the key distribution regions of insignificant geometric distortion are extracted by a relative total variation model, and the features of these distortions are measured by the interaction of decentralized attention and concentrated attention on top-down layers. By integrating the features of both bottom-up and top-down layers, a more visually perceptive quality evaluation model is built. Experimental results show that the proposed method is superior to the state-of-the-art in assessing the quality of 3D synthesized images.     

Detectability of words and nonwords in two kinds of noise

Recent models of speech perception emphasize the possibility of interactions among different processing levels. There is evidence that the lexical status of an utterance (i.e., whether it is a meaningful word or not) may influence earlier stages of perceptual analysis. To test how far down such "top-down" influences might penetrate, an investigation was conducted to determine whether there is a difference in detectability of words and nonwords masked by amplitude-modulated or unmodulated broadband noise. The results were negative, suggesting either that the stages of perceptual analysis engaged in the detection task are impermeable to lexical top-down effects, or that the lexical level was not sufficiently activated to have any facilitative effect on perception.     

A micropatterned carbohydrate display for tissue engineering by self-assembly of heparin

A novel strategy to construct a fibroblast scaffold on substrates has been demonstrated via top-down photolithography and the subsequent bottom-up processes of molecular self-assembly and molecular recognition. 3-Aminopropyltrimethoxysilane (APS) self-assembled monolayer was micropatterned by photolithography. An anionic polysaccharide heparin was adsorbed selectively on the cationic APS region of the micropatterned substrate. Basic fibroblast growth factor (bFGF) was selectively bound to the displayed heparin region and then micropatterned cultivation of fibroblast cells was successful on the bFGF-heparin-APS substrate.     

Quantification of Gloss Perception as a Function of Stimulus Duration

The mechanism and temporal characteristics of gloss perception are not entirely clear. In addition, the formulation for predicting gloss perception from photometric values has not been established. In the present study, we conducted an experiment to measure several temporal characteristics of gloss perception in order to clarify the mechanism. All stimuli were rendered as computer graphics with Phong and Lambert models to provide gloss perception to human observers. We measured perceptual glossiness with a magnitude estimation method and perceptual diffuse/specular reflectance of test stimuli with a matching method under several stimulus conditions, such as reflectance coefficients and stimulus duration. The results showed that the perceptual specular component and perceptual glossiness increase with decreasing stimulus duration. Finally, we proposed a formulation to predict perceptual glossiness as a function of stimulus duration.     

Theoretical aspects of neutrino mass and lepton flavour violation

We consider lepton flavour violation (LFV) in the charged lepton sector both from the bottom-up effective Lagrangian approach and from the top-down approach via various case studies that have been analysed. The implications for LFV studies at the LHC is briefly discussed. Finally the nature of LFV in the neutrino sector is considered, paying particular regard to the implications of the recent measurements of ?? ₁₃.     

Personalized PageRank Clustering: A graph clustering algorithm based on random walks

Graph clustering has been an essential part in many methods and thus its accuracy has a significant effect on many applications. In addition, exponential growth of real-world graphs such as social networks, biological networks and electrical circuits demands clustering algorithms with nearly-linear time and space complexity. In this paper we propose Personalized PageRank Clustering (PPC) that employs the inherent cluster exploratory property of random walks to reveal the clusters of a given graph. We combine random walks and modularity to precisely and efficiently reveal the clusters of a graph. PPC is a top-down algorithm so it can reveal inherent clusters of a graph more accurately than other nearly-linear approaches that are mainly bottom-up. It also gives a hierarchy of clusters that is useful in many applications. PPC has a linear time and space complexity and has been superior to most of the available clustering algorithms on many datasets. Furthermore, its top-down approach makes it a flexible solution for clustering problems with different requirements.     

Percept-related activity in the human somatosensory system: functional magnetic resonance imaging studies

In this paper, we review blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) studies addressing the neural correlates of touch, thermosensation, pain and the mechanisms of their cognitive modulation in healthy human subjects. There is evidence that fMRI signal changes can be elicited in the parietal cortex by stimulation of single mechanoceptive afferent fibers at suprathreshold intensities for conscious perception. Positive linear relationships between the amplitude or the spatial extents of BOLD fMRI signal changes, stimulus intensity and the perceived touch or pain intensity have been described in different brain areas. Some recent fMRI studies addressed the role of cortical areas in somatosensory perception by comparing the time course of cortical activity evoked by different kinds of stimuli with the temporal features of touch, heat or pain perception. Moreover, parametric single-trial functional MRI designs have been adopted in order to disentangle subprocesses within the nociceptive system.

Available evidence suggest that studies that combine fMRI with psychophysical methods may provide a valuable approach for understanding complex perceptual mechanisms and top-down modulation of the somatosensory system by cognitive factors specifically related to selective attention and to anticipation. The brain networks underlying somatosensory perception are complex and highly distributed. A deeper understanding of perceptual-related brain mechanisms therefore requires new approaches suited to investigate the spatial and temporal dynamics of activation in different brain regions and their functional interaction.     

Self-assembling of Mn12 molecular nanomagnets on FIB-patterned Au dot matrix

We have developed a novel strategy to build arrays of magnetic nanodots on the 100 nm scale, which exploits the potentialities of both bottom-up and top-down approaches, by self-assembling sulfur-functionalized Mn12 single molecule magnets (SMMs) on patterned Au dot matrices nanofabricated by FIB (focus ion beam). In this way, we demonstrate the capability to assemble SMMs in ordered arrays, where the magnetic information can be easily addressed, being the single bit represented by a 2D distribution of few hundred Mn12 clusters, grafted on top of each 100 × 100 nm² Au dot. Moreover, the chosen Mn12 functionalization is expected to favour a preferential orientation of the grafted molecule with the easy magnetization axis normal to the surface.     

Perceptual similarity of regional dialects of American English

Previous research on the perception of dialect variation has measured the perceptual similarity of talkers based on regional dialect using only indirect methods. In the present study, a paired comparison similarity ratings task was used to obtain direct measures of perceptual similarity. Naive listeners were asked to make explicit judgments about the similarity of a set of talkers based on regional dialect. The talkers represented four regional varieties of American English and both genders. Results revealed an additive effect of gender and dialect on mean similarity ratings and two primary dimensions of perceptual dialect similarity: geography (northern versus southern varieties) and dialect markedness (many versus few characteristic properties). The present findings are consistent with earlier research on the perception of dialect variation, as well as recent speech perception studies which demonstrate the integral role of talker gender in speech perception.     

Luminance and Chromaticity Conditions of a Bichromatic Cross Pattern for Chromatically-Uniform Transparency

We can perceive a surface through another surface. This perception is called transparency. It is known that transparency can be perceived even if the stimulus conditions are not consistent with physical conditions for a real transparent surface. In this study, we measured the ranges of luminance and chromaticity of the overlapping area of two crossed layers at which a surface was perceived as chromatically-uniform transparent. As the results, the luminance range of the overlapping area existed around or near the luminance of the inducing area. The upper and lower limits of the luminance range were higher for the dark background than for the light background. Moreover, the chromatic range existed around the additive colormixture line between two chromaticities of the inducing areas for both dark and light backgrounds. This indicates that the perceptual transparency mechanism would divide the color of an additive color mixture into the original colors that exist in the inducing areas. We noticed that the perceptual appearance of the stimulus changed greatly depending on the luminances of the overlapping area and the background. These differences in perceptual appearance would be a factor explaining individual difference and deciding the luminance conditions for transparency.     

半导体纳米激光

半导体纳米激光的研究是目前纳米技术（或纳米光子学）和半导体激光交汇产生的研究前沿。本文将综述这一领域最近一些最激动人心的进展。我们将集中讨论两种半导体纳米结构的纳米激光：自下而上生长而成的纳米线和自上而下刻蚀制成的纳米柱状结构。本文将综述这些纳米激光器的特殊特征,特别是利用表面等离子效应而成制成的金属{半导体等离子体激光,即目前世界上最小激光器的最新进展。由于这些纳米激光器的微小的尺寸以及对光在空间限制增强,我们必须重新检验半导体激光器中某些熟悉的概念在纳米尺度上的正确性和含义,例如模式增益和光限制因子（CF）的概念。本文将从统一的观点解释光限制因子在电介质和等离子体纳米激光器中的某些似乎反常的行为。在本文的通篇论述中,我们将尝试回答究竟激光器的尺寸能够小到什么程度,或者激光器的尺寸是否存在一个最小极限等基本问题。     

Objective Indices of Perceived Vocal Strain

BackgroundA limited number of experiments have investigated the perception of strain compared to the voice qualities of breathiness and roughness despite its widespread occurrence in patients who have hyperfunctional voice disorders, adductor spasmodic dysphonia, and vocal fold paralysis among others.ObjectiveThe purpose of this study is to determine the perceptual basis of strain through identification and exploration of acoustic and psychoacoustic measures.MethodsTwelve listeners evaluated the degree of strain for 28 dysphonic phonation samples on a five-point rating scale task. Computational estimates based on cepstrum, sharpness, and spectral moments (linear and transformed with auditory processing front-end) were correlated to the perceptual ratings.ResultsPerceived strain was strongly correlated with cepstral peak prominence, sharpness, and a subset of the spectral metrics. Spectral energy distribution measures from the output of an auditory processing front-end (ie, excitation pattern and specific loudness pattern) accounted for 77–79% of the model variance for strained voices in combination with the cepstral measure.ConclusionsModeling the perception of strain using an auditory front-end prior to acoustic analysis provides better characterization of the perceptual ratings of strain, similar to our prior work on breathiness and roughness. Results also provide evidence that the sharpness model of Fastl and Zwicker (2007) is one of the strong predictors of strain perception.     

Electroless formation of silver nanoaggregates: an experimental and molecular dynamics approach

The ability to manipulate matter to create non-conventional structures is one of the key issues of material science. The understanding of assembling mechanism at the nanoscale allows us to engineer new nanomaterials, with physical properties intimately depending on their structure.

This paper describes new strategies to obtain and characterise metal nanostructures via the combination of a top-down method, such as electron beam lithography, and a bottom-up technique, such as the chemical electroless deposition. We realised silver nanoparticle aggregates within well-defined patterned holes created by electron beam lithography on silicon substrates. The quality characteristics of the nanoaggregates were verified by using scanning electron microscopy and atomic force microscopy imaging. Moreover, we compared the experimental findings to molecular dynamics simulations of nanoparticles growth. We observed a very high dependence of the structure characteristics on the pattern nanowell aspect ratio. We found that high-quality metal nanostructures may be obtained in patterns with well aspect ratio close to one, corresponding to a maximum diameter of 50 nm, a limit above which the fabricated structures become less regular and discontinuous. When regular shapes and sizes are necessary, as in nanophotonics, these results suggest the pattern characteristics to obtain isolated, uniform and reproducible metal nanospheres.     

Bioinspired tactile perception platform with information encryption function

Mimicking tactile perception is critical to the development of advanced interactive neuromorphic platforms. Inspired by cutaneous perceptual functions, a bionic tactile perceptual platform is proposed. PDMS-based tactile sensors act as bionic skin touch receptors. Flexible indium tin oxide neuromorphic transistors fabricated with a single-step mask processing act as artificial synapses. Thus, the tactile perceptual platform possesses the ability of information processing. Interestingly, the flexible tactile perception platform can find applications in information encryption and decryption. With adoption of cipher, signal transmitted by the perception platform is encrypted. Thus, the security of information transmission is effectively improved. The flexible tactile perceptual platform would have potentials in cognitive wearable devices, advanced human-machine interaction system, and intelligent bionic robots.     

Dynamics of excited states in nanoscale materials

This tutorial provides a broad perspective on the synthesis, characterization, and size-dependent dynamics of nanoscale materials. Synthetic strategies include bottom-up, top-down, and hybrid strategies in gas and condensed phases. Advances in imaging and structure analysis provide the spatial information to correlate dynamic phenomena to structure in complex nanocomposites. Excited-state dynamics can change with material dimensions due to changes in the properties of the host and due to unique nanoscale phenomena such as plasmon resonance in metals and quantum confinement in semiconductors.     

On the matching of top-down knowledge with sensory input in the perception of ambiguous speech

Background

How does the brain repair obliterated speech and cope with acoustically ambivalent situations? A widely discussed possibility is to use top-down information for solving the ambiguity problem. In the case of speech, this may lead to a match of bottom-up sensory input with lexical expectations resulting in resonant states which are reflected in the induced gamma-band activity (GBA).

Methods

In the present EEG study, we compared the subject's pre-attentive GBA responses to obliterated speech segments presented after a series of correct words. The words were a minimal pair in German and differed with respect to the degree of specificity of segmental phonological information.

Results

The induced GBA was larger when the expected lexical information was phonologically fully specified compared to the underspecified condition. Thus, the degree of specificity of phonological information in the mental lexicon correlates with the intensity of the matching process of bottom-up sensory input with lexical information.

Conclusions

These results together with those of a behavioural control experiment support the notion of multi-level mechanisms involved in the repair of deficient speech. The delineated alignment of pre-existing knowledge with sensory input is in accordance with recent ideas about the role of internal forward models in speech perception.

     

Chinese characters reveal impacts of prior experience on very early stages of perception

Background  

Visual perception is strongly determined by accumulated experience with the world, which has been shown for shape, color, and position perception, in the field of visuomotor learning, and in neural computation. In addition, visual perception is tuned to statistics of natural scenes. Such prior experience is modulated by neuronal top-down control the temporal properties of which had been subject to recent studies. Here, we deal with these temporal properties and address the question how early in time accumulated past experience can modulate visual perception.     

Perceptual differences between vowels located in a limited phonetic space

The perception of subphonemic differences between vowels was investigated using multidimensional scaling techniques. Three experiments were conducted with natural-sounding synthetic stimuli generated by linear predictive coding (LPC) formant synthesizers. In the first experiment, vowel sets near the pairs (i-I), (epsilon-ae), or (u-U) were synthesized containing 11 vowels each. Listeners judged the dissimilarities between all pairs of vowels within a set several times. These perceptual differences were mapped into distances between the vowels in an n-dimensional space using two-way multidimensional scaling. Results for each vowel set showed that the physical stimulus space, which was specified by the two parameters F1 and F2, was always mapped into a two-dimensional perceptual space. The best metric for modeling the perceptual distances was the Euclidean distance between F1 and F2 in barks. The second experiment investigated the perception of the same vowels from the first experiment, but embedded in a consonantal context. Following the same procedures as experiment 1, listeners' perception of the (bv) dissimilarities was not different from their perception of the isolated vowel dissimilarities. The third experiment investigated dissimilarity judgments for the three vowels (ae-alpha-lambda) located symmetrically in the F1 X F2 vowel space. While the perceptual space was again two dimensional, the influence of phonetic identity on vowel difference judgments was observed. Implications for determining metrics for subphonemic vowel differences using multidimensional scaling are discussed.