Sparse representation based stereoscopic image quality assessment accounting for perceptual cognitive process

In this paper, we propose a sparse representation based Reduced-Reference Image Quality Assessment (RR-IQA) index for stereoscopic images from the following two perspectives: 1) Human visual system (HVS) always tries to infer the meaningful information and reduces uncertainty from the visual stimuli, and the entropy of primitive (EoP) can well describe this visual cognitive progress when perceiving natural images. 2) Ocular dominance (also known as binocularity) which represents the interaction between two eyes is quantified by the sparse representation coefficients. Inspired by previous research, the perception and understanding of an image is considered as an active inference process determined by the level of “surprise”, which can be described by EoP. Therefore, the primitives learnt from natural images can be utilized to evaluate the visual information by computing entropy. Meanwhile, considering the binocularity in stereo image quality assessment, a feasible way is proposed to characterize this binocular process according to the sparse representation coefficients of each view. Experimental results on LIVE 3D image databases and MCL database further demonstrate that the proposed algorithm achieves high consistency with subjective evaluation

Quality assessment metric of stereo images considering cyclopean integration and visual saliency

In recent years, there has been great progress in the wider use of three-dimensional (3D) technologies. With increasing sources of 3D content, a useful tool is needed to evaluate the perceived quality of the 3D videos/images. This paper puts forward a framework to evaluate the quality of stereoscopic images contaminated by possible symmetric or asymmetric distortions. Human visual system (HVS) studies reveal that binocular combination models and visual saliency are the two key factors for the stereoscopic image quality assessment (SIQA) metric. Therefore inspired by such findings in HVS, this paper proposes a novel saliency map in SIQA metric for the cyclopean image called “cyclopean saliency”, which avoids complex calculations and produces good results in detecting saliency regions. Moreover, experimental results show that our metric significantly outperforms conventional 2D quality metrics and yields higher correlations with human subjective judgment than the state-of-art SIQA metrics. 3D saliency performance is also compared with “cyclopean saliency” in SIQA. It is noticed that the proposed metric is applicable to both symmetric and asymmetric distortions. It can thus be concluded that the proposed SIQA metric can provide an effective evaluation tool to assess stereoscopic image quality

Mapping Hydration Dynamics around a β‑Barrel Protein

Protein surface hydration is fundamental to its structure, flexibility, dynamics, and function, but it has been challenging to disentangle their ultimate relationships. Here, we report our systematic characterization of hydration dynamics around a β-barrel protein, rat liver fatty acid-binding protein (rLFABP), to reveal the effect of different protein secondary structures on hydration water. We employed a tryptophan scan to the protein surface one at a time and examined a total of 17 different sites. We observed three types of hydration water relaxation with distinct time scales, from hundreds of femtoseconds to a hundred picoseconds. We also examined the anisotropy dynamics of the corresponding tryptophan side chains and observed two distinct relaxations from tens to hundreds of picoseconds. Integrating our previous findings on α-helical proteins, we conclude the following: (1) The hydration dynamics is highly heterogeneous around the protein surface of both α-helical and β-sheet proteins. The outer-layer water of the hydration shell behave like a bulk and relaxes in hundreds of femtoseconds. The inner-layer water collectively relaxes in two time scales, reorientation motions in a few picoseconds and network restructuring in tens to a hundred picoseconds. (2) The hydration dynamics are always faster than local protein relaxations and in fact drive the protein fluctuations on the picosecond time scale. (3) The hydration dynamics in general are more retarded around β-sheet structures than α-helical motifs. A thicker hydration shell and a more rigid interfacial hydration network are observed in the β-sheet protein. Overall, these findings elucidate the intimate relationship between water–protein interactions and dynamics on the ultrafast time scale

The role of MALAT-1 in the invasion and metastasis of gastric cancer

<p><b>Objectives:</b> The long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT-1) has been reported to be over-expressed in several cancer types. However, its role in gastric cancer (GC) remains unclear. In the present study, we examined the expression of MALAT-1 in GC cells and tissues and explored its role in GC cell migration and invasion.</p> <p><b>Materials and methods:</b> Real-time quantitative polymerase chain reaction (qRT-PCR) was used to analyze the expression level of MALAT-1 in six GC cell lines and 20 gastric tissues (20 GC and 20 adjacent normal mucosa). Functional characterization for the role of MALAT-1 in GC was performed by small interfering RNA (siRNA) knockdown, followed by series of <i>in vitro</i> and <i>in vivo</i> experiments.</p> <p><b>Results:</b> MALAT-1 was upregulated in GC cell lines and tissues compared with the immortalized gastric epithelial cell line GES and adjacent normal tissues, respectively. Moreover, MALAT-1 expression was higher in the high-metastatic-potential GC cell line SGC7901M than in the low-metastatic-potential GC cell line SGC7901NM. <i>In vitro</i> and <i>in vivo</i> assays showed that siRNA-mediated silencing of MALAT-1 inhibited GC cell migration and invasion. In addition, suppressing MALAT-1 expression resulted in a decrease in the expression of the Epithelial-mesenchymal transition (EMT)-associated marker vimentin and an increase in the expression of E-cadherin at both the mRNA and protein levels.</p> <p><b>Conclusions:</b> MALAT-1 may promote the migration and invasion of GC cells in part by regulating EMT.</p