Biography:

In the past Lei Liu has collaborated on articles with Christoph J. Feinauer and Jian Liang. One of their most recent publications is A polar coordinate system for describing binocular disparity. Which was published in journal Vision Research.

More information about Lei Liu research including statistics on their citations can be found on their Copernicus Academic profile page.

Lei Liu's Articles: (355)

A polar coordinate system for describing binocular disparity

AbstractWhen a meridional magnifier is introduced in front of one eye, a planar surface is perceived as slanted about a vertical axis. If the horizontal meridian is magnified, the perceived slant is away from the eye with the magnifier (geometric effect). If the vertical meridian is magnified, the slant is towards the eye with the magnifier (induced effect). While the geometric effect can be explained by the binocular horizontal disparities introduced by the horizontal magnifier, the induced effect has to be explained differently. Various models have been developed and the induced effect has generally been explained as a reinterpretation of horizontal disparity under a new reference of stereoscopic localization which is resultant from the vertical positional disparity introduced by the vertical magnifier. In this paper we describe binocular disparity in a polar coordinate system. Under this system, horizontal and vertical disparities are combined into a single stimulus variable, polar angle disparity. We show that the spatial distribution of polar angle disparity can faithfully describe the three-dimensional slant and inclination of a planar surface relative to the gaze normal plane. Both geometric and induced effects can be explained as direct responses to the polar angle disparity map distorted by the magnifier. Theoretical predictions based on the polar angle disparity are compared with experimental findings.

Chapter Three - Zinc Finger Proteins and the 3D Organization of Chromosomes

AbstractZinc finger domains are one of the most common structural motifs in eukaryotic cells, which employ the motif in some of their most important proteins (including TFIIIA, CTCF, and ZiF268). These DNA binding proteins contain up to 37 zinc finger domains connected by flexible linker regions. They have been shown to be important organizers of the 3D structure of chromosomes and as such are called the master weaver of the genome.Using NMR and numerical simulations, much progress has been made during the past few decades in understanding their various functions and their ways of binding to the DNA, but a large knowledge gap remains to be filled. One problem of the hitherto existing theoretical models of zinc finger protein DNA binding in this context is that they are aimed at describing specific binding. Furthermore, they exclusively focus on the microscopic details or approach the problem without considering such details at all. We present the Flexible Linker Model, which aims explicitly at describing nonspecific binding. It takes into account the most important effects of flexible linkers and allows a qualitative investigation of the effects of these linkers on the nonspecific binding affinity of zinc finger proteins to DNA.Our results indicate that the binding affinity is increased by the flexible linkers by several orders of magnitude. Moreover, they show that the binding map for proteins with more than one domain presents interesting structures, which have been neither observed nor described before, and can be interpreted to fit very well with existing theories of facilitated target location. The effect of the increased binding affinity is also in agreement with recent experiments that until now have lacked an explanation.We further explore the class of proteins with flexible linkers, which are unstructured until they bind. We have developed a methodology to characterize these flexible proteins. Employing the concept of barcodes, we propose a measure to compare such flexible proteins in terms of a similarity measure. This measure is validated by a comparison between a geometric similarity measure and the topological similarity measure that takes geometry as well as topology into account.

1 - Introduction

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6 - Case Study of a Piezoelectric Steering Platform

AbstractThe measurement and control strategy for a piezoelectric-based platform using strain gauge sensors and a robust composite controller is investigated in this chapter. First, we construct the experimental setup using a piezoelectric-based platform, strain gauge sensors, an AD5435 platform, and two voltage amplifiers. Then, we present the measurement strategy to measure accurately the tip/tilt angles on the order of subradians. Also, we present the comprehensive design of a composite control strategy to enhance the tracking accuracy with a novel driving principle. Finally, an experiment is presented to validate the measurement and control strategy. The experimental results demonstrate that the proposed measurement and control strategy provides accurate angle motion with a root mean square error of 0.21 rad that is approximately equal to the noise level.

Preface

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Preface

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Regular articleVascular biology, atherosclerosis, and endothelium biologyTLR9 Agonist Regulates Angiogenesis and Inhibits Corneal Neovascularization

Myeloid cells are highly adaptable and may positively or negatively regulate angiogenesis dependent on the cognate and soluble signals they receive. Toll-like receptors (TLRs) initiate immune responses, orchestrate adaptive immune responses, and regulate vascular endothelial growth factor (VEGF)–mediated angiogenesis during wound healing. We investigated the possible role of TLR ligands in attenuation of new vessel growth via regulation of expression of VEGF or soluble fms-like tyrosine kinase-1 (sFlt-1) in both an aortic ring assay and a model of suture-induced corneal angiogenesis. The TLR3 ligand [poly(I:C)] markedly suppressed VEGF secretion and stimulated sFlt-1 release from macrophages. The aortic ring assay demonstrated that new vessels were promoted by the TLR2 ligand (heat killed Listeria monocytogenes) and the TLR4 ligand (lipopolysaccharide), concomitant with increased VEGF and matrix metalloproteinase 9 secretion. In contrast, the TLR9 ligand [oligodeoxynucleotide (ODN)1826] stimulated sFlt-1 secretion from macrophages and reduced the number of aortic ring vessel sprouts. ODN1826 also significantly reduced the length and volume of both hemangiogenesis and lymphangiogenesis in the suture-induced corneal angiogenesis model. Furthermore, 53 angiogenic factors were examined via protein array and compared between ODN1826- and water-treated corneas to interrogate the pathway of ODN1826 inhibition, demonstrating an up-regulation of Serpin E1 signal. Further clinical and IHC analyses of the aortic ring assay indicated that TLR9 suppressed tip cell migration and recruitment of mural cells and adventitial macrophages.

Dexamethasone rapidly inhibits glucose uptake via non-genomic mechanisms in contracting myotubes

Highlights•Dexamethasone rapidly suppresses contraction-stimulated glucose uptake in C2C12 myotubes.•AMPK, CaMKII, and Glut4 are involved in the signaling pathways of dexamethasone.•The inhibitory effects of GC on glucose uptake are mediated by non-genomic mechanisms.

Effects of γ-secretase inhibition on the proliferation and vitamin D3 induced osteogenesis in adipose derived stem cells

AbstractAs a γ-secretase inhibitor, DAPT has been widely used to evaluate the biological behaviors and Notch signaling pathway in various cells. This study was aimed to examine the effects of DAPT on the growth and vitamin D3 induced osteogenesis in adipose derived stem cells (ASCs). The cells were treated with or without DAPT and induced to osteoblastic lineage in the presence of vitamin D3. Alizarin red staining and real-time PCR results indicated that the addition of DAPT to vitamin D3 treatments enhanced osteogenesis in ASCs. According to the fold increase and colony-forming unit assay results, the cells cultured in DAPT exhibited lower proliferation rate than those cultured in control medium. Hey1, expressed in the nucleus of ASCs to act as a transcriptional repressor, was downregulated when Notch signaling was inhibited by DAPT. Whereas the expression of Runx2 increased in the nucleus of osteogenic induced ASCs after DAPT treatment. This study demonstrated that DAPT reduced the proliferation and enhanced the osteogenesis in ASCs via regulation of Notch and Runx2 expression.

Inhibition of COX-2 and 5-LOX regulates the progression of colorectal cancer by promoting PTEN and suppressing PI3K/AKT pathway

Highlights•Inhibitors of COX-2 and 5-LOX can suppress the invasion, proliferation and decrease the content of ROS in colorectal cancer cells.•COX-2 and 5-LOX knockout can reduce the tumorigenesis in ApcMin/+ mice.•The mechanism may be associated with activating PTEN and further suppressing PI3K/AKT pathway.

Circular RNA circMTO1 suppresses bladder cancer metastasis by sponging miR-221 and inhibiting epithelial-to-mesenchymal transition

Highlights•Lower circMTO1 levels were positively correlated with bladder cancer patients' metastasis and poorer survival.•Ectopic expression of circMTO1 in bladder cancer cells inhibited cell's EMT and metastasis.•CircMTO1 negatively regulated the EMT pathway by competing for miR-221.

Regular ArticleA Neurohormone Regulating both Methyl Farnesoate Synthesis and Glucose Metabolism in a Crustacean☆

AbstractMethyl farnesoate (MF) has been identified as a juvenile hormone-like compound in crustacea which has central roles in the regulation of development and reproduction. To study the regulation of MF synthesis, we isolated a neuropeptide which inhibits MF synthesis from the neurohemal organ--sinus gland X-organ complex of the spider crabLibinia emarginata.The primary structure of this neuropeptide has been determined. It has 72 amino acid residues (deduced molecular mass 8490.5 Da) with pyroglutamic acid at the N-terminus and NH2at the C-terminus. It shares a high percentage of sequence identity with other sinus gland neuropeptids which form the unique family of CHH neuropeptides of crustacea. Activity studies showed that this neurohormone has dual effects: it inhibited MF synthesisin vitroand had hyperglycemic activity when injected into crabs.

Enhanced electromagnetic wave absorption of nanoporous Fe3O4 @ carbon composites derived from metal-organic frameworks

AbstractElectromagnetic wave absorbing materials have been widely applied in the wireless communication, electronic devices, and radar technology. In this work, metal-organic frameworks derived nanoporous Fe3O4 @ carbon ([email protected]) composites were successfully obtained by a simple method. Electromagnetic wave absorbing performances were significantly enhanced due to the optimal impedance matching and strong attenuation via the synergy between the dielectric loss and the magnetic loss. As a result, the [email protected] composites exhibited excellent electromagnetic wave absorbing properties, in which a strong reflection loss (RL) of −65.5 dB at 9.8 GHz as well as a wide absorbing bandwidth of 4.5 GHz (RL  <  −10 dB) with a matching thickness of 3.0 mm were achieved. Therefore, the present work can provide a new paradigm for the design and synthesis of electromagnetic wave absorbing materials possessing a promising application potential.

Manifestation of aromaticity and its effects on the electronic structure of finite single-wall carbon nanotubes

AbstractFinite single-wall carbon nanotubes (p,q), characterized by p=n+l+1, q=n−l, 0⩽l⩽n, and n=1,2,…, consisting of even nanotube (NT) sections may be viewed as a chain of aromatic `molecules' with each `molecular-unit' consisting of two NT sections of 4n+2 sp2-bonded carbon atoms. Such (group II) NTs, have large energy gaps for short tubes, whereas for tubes of intermediate lengths, the energy gap decreases monotonically as a function of NT length. The energy gap behaviors are totally different from the previously studied group I NTs with p=n+l and q=n−l, which exhibited oscillatory characteristics.

A temperature-regulated molecular redox fluorescence switch based on a triad bearing tetrathiafulvalene, maleimide and pyrene moieties

AbstractTriad 1 consisting of TTF, maleimide and pyrene units acts as a temperature-regulated molecular redox fluorescence switch by combining features of the three moieties. Our results show that the fluorescence modulation by redox reaction of TTF unit in triad 1 is controlled by the ‘status’ of the maleimide unit which is involved in the reversible temperature-dependent Diels–Alder reaction with furan. Thus, a resettable temperature-regulated molecular redox fluorescence switch is successfully realized with triad 1.

Salinomycin suppresses cancer cell stemness and attenuates TGF-β-induced epithelial-mesenchymal transition of renal cell carcinoma cells

Highlights•Salinomycin inhibits the proliferation of RCC cells.•Salinomycin reduces the stemness of RCC cells.•Salinomycin attenuates the TGF-β induced EMT of RCC cells.•Salinomycin suppresses the activity of Hedgehog signaling pathway.

Effects of 72 hours total sleep deprivation on male astronauts' executive functions and emotion

AbstractBackgroundTo provide evidence for better understanding stressful situations, the present study was designed to investigate the specific physiological and psychological responses under stressful situations like social isolation and sleep deprivation.MethodsTwelve healthy male adults (age: 18–30 years old) who participated in our study were randomized to the 72 hours of social isolation and 72 hours of sleep deprivation experimental conditions. Performances (event-related potentials and physiological activities) on the Go/Nogo task which reflected the executive functions were accessed at baseline (pretest) and after 72-hour of the experiment (posttest).ResultsThe results showed that compared to the social isolation, the participants got strengthened heart rate (HR), weakened HR variability and smaller amplitude of the P300 under the sleep deprivation condition; moreover, they had lower positive emotion and higher negative mood in the posttest.ConclusionsThe present study indicated that sleep deprivation specifically influenced the intensity of task-relevant information processing, mood and vagal tone.

Ablation in different heat fluxes of C/C composites modified by ZrB2–ZrC and ZrB2–ZrC–SiC particles

Highlights•Two heat fluxes were used to evaluate the ablation of modified C/C composites.•C/C–ZrB2–ZrC–SiC has the lowest ablation rate under a heat flux of 2.38 MW/m2.•Ablation rates of C/C shows the smallest increase with increase in heat flux.•Thermal mismatch and evaporation of SiO2 dominate variations in the ablation behavior.

Effect of SiC/ZrC ratio on the mechanical and ablation properties of C/C–SiC–ZrC composites

Highlights•C/C composites modified by SiC nanowires reinforced SiC–ZrC ceramics were prepared.•Composites with SiC/ZrC ratio of 1:1.5 exhibit a good mechanical performance.•ZrO2–SiO2 controlled by SiC/ZrC ratio plays a key role in ablation behavior.•The SiC/ZrC ratio has a similar effect on mechanical and ablation behavior.

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