Robust Adaptive Control of a Class of Nonlinear Strict-feedback Discrete-time Systems with Exact Output Tracking

10.1016/j.automatica.2009.07.025Automatica45112537-2545ATCA

Impact of image-based motion correction on dopamine D3/D2 receptor occupancy-comparison of groupwise and frame-by-frame registration approaches

© 2015, Jiao et al.Background: Image registration algorithms are frequently used to align the reconstructed brain PET frames to remove subject head motion. However, in occupancy studies, this is a challenging task where competitive binding of a drug can further reduce the available signal for registration. The purpose of this study is to evaluate two kinds of algorithms—a conventional frame-by-frame (FBF) registration and a recently introduced groupwise image registration (GIR), for motion correction of a dopamine D3/D2 receptor occupancy study. Methods: The FBF method co-registers all the PET frames to a common reference based on normalised mutual information as the spatial similarity. The GIR method incorporates a pharmacokinetic model and conducts motion correction by maximising a likelihood function iteratively on tracer kinetics and subject motion. Data from eight healthy volunteers scanned with [11C]-(+)-PHNO pre- and post-administration of a range of doses of the D3 antagonist GSK618334 were used to compare the motion correction performance. Results: The groupwise registration achieved improved motion correction results, both by visual inspection of the dynamic PET data and by the reduction of the variability in the outcome measures, and required no additional steps to exclude unsuccessfully realigned PET data for occupancy modelling as compared to frame-by-frame registration. Furthermore, for the groupwise method, the resultant binding potential estimates had reduced variation and bias for individual scans and improved half maximal effective concentration (EC50) estimates were obtained for the study as a whole. Conclusions: These results indicate that the groupwise registration approach can provide improved motion correction of dynamic brain PET data as compared to frame-by-frame registration approaches for receptor occupancy studies

1-[4-(2-Chloro­eth­oxy)-2-hy­droxy­phen­yl]ethanone

In the title compound, C10H11ClO3, obtained by the reaction of 2,4-dihy­droxy­acetophenone, potassium carbonate and 1-bromo-2-chloro­ethane, an intra­molecular O—H⋯O hydrogen bond occurs

Alignment layer effects on thin liquid crystal cells

Factors affecting the thin cell performance of a liquid crystal cell are analyzed. Examples based on vertically aligned thin cells are given to illustrate these effects. When the cell gap is below similar to 2 mu m, the liquid crystal alignment material, layer thickness, and anchoring energy all play important roles. The first two factors affect the threshold and on-state voltage, while the last one affects the operating voltage and response time. Three reflective liquid crystal cells are studied experimentally. Good agreement between experiment and theory is obtained. (c) 2008 American Institute of Physics

Vibrational Properties of One-Dimensional Disordered Hyperuniform Atomic Chains

Disorder hyperuniformity (DHU) is a recently discovered exotic state of many-body systems that possess a hidden order in between that of a perfect crystal and a completely disordered system. Recently, this novel DHU state has been observed in a number of quantum materials including amorphous 2D graphene and silica, which are endowed with unexpected electronic transport properties. Here, we numerically investigate 1D atomic chain models, including perfect crystalline, disordered hyperuniform as well as randomly perturbed atom packing configurations to obtain a quantitative understanding of how the unique DHU disorder affects the vibrational properties of these low-dimensional materials. We find that the DHU chains possess lower cohesive energies compared to the randomly perturbed chains, implying their potential reliability in experiments. Our inverse partition ratio (IPR) calculations indicate that the DHU chains can support fully delocalized states just like perfect crystalline chains over a wide range of frequencies, i.e., $\omega \in (0, 100)$ cm$^{-1}$, suggesting superior phonon transport behaviors within these frequencies, which was traditionally considered impossible in disordered systems. Interestingly, we observe the emergence of a group of highly localized states associated with $\omega \sim 200$ cm$^{-1}$, which is characterized by a significant peak in the IPR and a peak in phonon density of states at the corresponding frequency, and is potentially useful for decoupling electron and phonon degrees of freedom. These unique properties of DHU chains have implications in the design and engineering of novel DHU quantum materials for thermal and phononic applications.Comment: 6 pages, 3 figure

Planar Cell Polarity Signaling Pathway in Congenital Heart Diseases

Congenital heart disease (CHD) is a common cardiac disorder in humans. Despite many advances in the understanding of CHD and the identification of many associated genes, the fundamental etiology for the majority of cases remains unclear. The planar cell polarity (PCP) signaling pathway, responsible for tissue polarity in Drosophila and gastrulation movements and cardiogenesis in vertebrates, has been shown to play multiple roles during cardiac differentiation and development. The disrupted function of PCP signaling is connected to some CHDs. Here, we summarize our current understanding of how PCP factors affect the pathogenesis of CHD

Electro-optics of polymer-stabilized blue phase liquid crystal displays

Electro-optics of polymer-stabilized blue phase liquid crystal displays (BP LCDs) is analyzed and validated experimentally. A numerical model for characterizing and optimizing the electro-optical and display properties of BP LCDs in in-plane switching and fringe field switching cells is developed. The simulated voltage-dependent transmittance curves agree well with the measured results. To lower the operating voltage while keeping a high transmittance, both electrode width and gap, and large Kerr constant make important contributions. A wide-view BP LCD using a single biaxial compensation film is simulated

Stone-Wales Defects Preserve Hyperuniformity in Amorphous Two-Dimensional Materials

Crystalline two-dimensional (2D) materials such as graphene possess unique physical properties absent in their bulk form, enabling many novel device applications. Yet, little is known about their amorphous counterparts, which can be obtained by introducing the Stone-Wales (SW) topological defects via proton radiation. Here we provide strong numerical evidence that SW defects preserve hyperuniformity in hexagonal 2D materials, a recently discovered new state of matter characterized by vanishing normalized infinite-wavelength density fluctuations, which implies that all amorphous states of these materials are hyperuniform. Specifically, the static structure factor S(k) of these materials possesses the scaling S(k) ~ k^{\alpha} for small wave number k, where 1<=\alpha(p)<=2 is monotonically decreasing as the SW defect concentration p increases, indicating a transition from type-I to type-II hyperuniformity at p ~= 0.12 induced by the saturation of the SW defects. This hyperuniformity transition marks a structural transition from perturbed lattice structures to truly amorphous structures, and underlies the onset of strong correlation among the SW defects as well as a transition between distinct electronic transport mechanisms associated with different hyperuniformity classes

Palladium-Catalyzed Cascade Carbonylation to α,β-Unsaturated Piperidones via Selective Cleavage of Carbon-Carbon Triple Bonds

A direct and selective synthesis of α,β-unsaturated piperidones by a new palladium-catalyzed cascade carbonylation is described. In the presented protocol, easily available propargylic alcohols react with aliphatic amines to provide a broad variety of interesting heterocycles. Key to the success of this transformation is a remarkable catalytic cleavage of the present carbon–carbon triple bond by using a specific catalyst with 2-diphenylphosphinopyridine as ligand and appropriate reaction conditions. Mechanistic studies and control experiments revealed branched unsaturated acid 11 as crucial intermediate. © 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH Gmb

Birman-Wenzl-Murakami Algebra and the Topological Basis

In this paper, we use entangled states to construct 9x9-matrix representations of Temperley-Lieb algebra (TLA), then a family of 9x9-matrix representations of Birman-Wenzl-Murakami algebra (BWMA) have been presented. Based on which, three topological basis states have been found. And we apply topological basis states to recast nine-dimensional BWMA into its three-dimensional counterpart. Finally, we find the topological basis states are spin singlet states in special case.Comment: 11pages, 1 figur