Quantum simulation of topological Majorana bound states and their universal quantum operations using charge-qubit arrays

Majorana bound states have been a focus of condensed matter research for their potential applications in topological quantum computation. Here we utilize two charge-qubit arrays to explicitly simulate a DIII class one-dimensional superconductor model where Majorana end states can appear. Combined with one braiding operation, universal single-qubit operations on a Majorana-based qubit can be implemented by a controllable inductive coupling between two charge qubits at the ends of the arrays. We further show that in a similar way, a controlled-NOT gate for two topological qubits can be simulated in four charge-qubit arrays. Although the current scheme may not truly realize topological quantum operations, we elaborate that the operations in charge-qubit arrays are indeed robust against certain local perturbations.Comment: 5 pages, 3 figure

On the boundary of the numerical range of a matrix

AbstractA characterization of real matrices is given for which a diagonal entry of a matrix is a boundary point of its numerical range

Joint numerical range and its generating hypersurface

AbstractIn this paper, we study the joint numerical range of m-tuples of Hermitian matrices via their generating hypersurfaces. An example is presented which shows the invalidity of an analogous Kippenhahn theorem for the joint numerical range of three Hermitian matrices

Positive surface charge of GluN1 N-terminus mediates the direct interaction with EphB2 and NMDAR mobility.

Localization of the N-methyl-D-aspartate type glutamate receptor (NMDAR) to dendritic spines is essential for excitatory synaptic transmission and plasticity. Rather than remaining trapped at synaptic sites, NMDA receptors undergo constant cycling into and out of the postsynaptic density. Receptor movement is constrained by protein-protein interactions with both the intracellular and extracellular domains of the NMDAR. The role of extracellular interactions on the mobility of the NMDAR is poorly understood. Here we demonstrate that the positive surface charge of the hinge region of the N-terminal domain in the GluN1 subunit of the NMDAR is required to maintain NMDARs at dendritic spine synapses and mediates the direct extracellular interaction with a negatively charged phospho-tyrosine on the receptor tyrosine kinase EphB2. Loss of the EphB-NMDAR interaction by either mutating GluN1 or knocking down endogenous EphB2 increases NMDAR mobility. These findings begin to define a mechanism for extracellular interactions mediated by charged domains

Selecting additional tag SNPs for tolerating missing data in genotyping

BACKGROUND: Recent studies have shown that the patterns of linkage disequilibrium observed in human populations have a block-like structure, and a small subset of SNPs (called tag SNPs) is sufficient to distinguish each pair of haplotype patterns in the block. In reality, some tag SNPs may be missing, and we may fail to distinguish two distinct haplotypes due to the ambiguity caused by missing data. RESULTS: We show there exists a subset of SNPs (referred to as robust tag SNPs) which can still distinguish all distinct haplotypes even when some SNPs are missing. The problem of finding minimum robust tag SNPs is shown to be NP-hard. To find robust tag SNPs efficiently, we propose two greedy algorithms and one linear programming relaxation algorithm. The experimental results indicate that (1) the solutions found by these algorithms are quite close to the optimal solution; (2) the genotyping cost saved by using tag SNPs can be as high as 80%; and (3) genotyping additional tag SNPs for tolerating missing data is still cost-effective. CONCLUSION: Genotyping robust tag SNPs is more practical than just genotyping the minimum tag SNPs if we can not avoid the occurrence of missing data. Our theoretical analysis and experimental results show that the performance of our algorithms is not only efficient but the solution found is also close to the optimal solution

Controlled Levofloxacin Release and Antibacterial Properties of β-Cyclodextrins-Grafted Polypropylene Mesh Devices for Hernia Repair.

Mesh infection is a major complication of hernia repair. After knitted mesh implantation, bacteria can grow within textile structures causing infection. In this work, polypropylene (PP) mesh devices were two-step grafted with hexamethylene diisocyanate (HDI) and β⁻cyclodexrins (CD) and then loaded with suitable antimicrobial levofloxacin HCL for hernia mesh-infection prevention. First, oxygen plasma was able to create surface roughness, then HDI was successfully grafted onto PP fiber surfaces. Afterwards, CD was covalently grafted onto the HDI treated PP meshes, and levofloxacin HCL (LVFX) was loaded into the CD cavity of the modified meshes. The modified devices were evaluated for sustained antibiotic properties and drug-release profiles in a phosphate buffer, and sustained drug release was observed between interfaces of meshes and aqueous environment. The antibiotic-loaded PP mesh samples demonstrated sustained antibacterial properties for 7 and 10 days, respectively, against both Gram-negative and Gram-positive bacteria. The CD-captured levofloxacin HCL showed burst release after 6 h but later exhibited sustained release for the next 48 h. Among all samples, the modified mesh LVFX-6 was more stable and showed more sustained drug release and could be employed in future clinical applications

Situational Context and Marked Code-Switching

Based on Halliday’s theory of register, this paper concerns about marked code-switching from the perspective of sociolinguistic situational context. Marked code-switching does not happen at random, but a kind of rational behavior. The data are gathered from utterances occurred in different situational contexts, by which and based on the field, tenor and mode of register, this research has made a deep analysis on marked code-switch, its socio-pragmatic functions and psychological motivations as well. It does have some research value either in theory and application since there is seldom research done about the marked code-switching phenomenon from the perspective of register theory. Keywords: register theory; marked code-switching; socio-pragmatic functions Résumé: Sur la base de la théorie de registre de Halliday, cet article s’intéresse sur le code-switching marqué à partir de la perspective du contexte situationnel sociolinguistique. Le Code-switching marqué ne se fait pas au hasard. C’est une sorte de procédé rationnel. Les données sont recueillies à partir des énoncés produits dans de différents contextes situationnels et la recherche a fait une analyse profonde sur le code-switching marqué, ses fonctions socio-pragmatiques et aussi les motivations psychologiques. Elle possède une certaine valeur de recherche dans la théorie et dans l'application, car les recherches sur le phénomène de code-switching marqué sont rarement faites dans la perspective de la théorie de registre. Mots-clés: la théorie de register; le code-switching marqué; les fonctions socio-pragmatiques 摘 要：本文從社會語言學的情景語境角度，借助Halliday的語域理論探討在語言的使用中有標記語碼轉換現象。 有標記語碼轉換不是盲目隨意的，而是一種理性行為。本文以一些生活中的情景語境片段為語料，從語域理論的語場、語勢和語式三維變項角度分析了有標記語碼轉換現象、有標記語碼轉換的社會語用和心理動機。將語域理論用於研究有標記語碼轉換的研究不甚多見，因此本研究具有一定的理論和應用價值。 關鍵詞：語域理論；有標記語碼轉換；社會語用功

Visible-light promoted atom transfer radical addition-elimination (ATRE) reaction for the synthesis of fluoroalkylated alkenes using DMA as electron-donor

Here, we describe a mild, catalyst-free and operationally-simple strategy for the direct fluoroalkylation of olefins driven by the photochemical activity of an electron donor-acceptor (EDA) complex between DMA and fluoroalkyl iodides. The significant advantages of this photochemical transformation are high efficiency, excellent functional group tolerance, and synthetic simplicity, thus providing a facile route for further application in pharmaceuticals and life sciences