694 research outputs found

    Topological beaming of light

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    Nanophotonic light emitters are key components in numerous application areas because of their compactness and versatility. Here, we propose a topological beam emitter structure that takes advantage of submicrometer footprint size, small divergence angle, high efficiency, and adaptable beam shaping capability. The proposed structure consists of a topological junction of two guided-mode resonance gratings inducing a leaky Jackiw-Rebbi state resonance. The leaky Jackiw-Rebbi state leads to in-plane optical confinement with funnel-like energy flow and enhanced emission probability, resulting in highly efficient optical beam emission. In addition, the structure allows adaptable beam shaping for any desired positive definite profiles by means of Dirac mass distribution control, which can be directly encoded in lattice geometry parameters. Therefore, the proposed approach provides highly desirable properties for efficient micro–light emitters and detectors in various applications including display, solid-state light detection and ranging, laser machining, label-free sensors, optical interconnects, and telecommunications

    Betacellulin-Induced Beta Cell Proliferation and Regeneration Is Mediated by Activation of ErbB-1 and ErbB-2 Receptors

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    BACKGROUND: Betacellulin (BTC), a member of the epidermal growth factor family, is known to play an important role in regulating growth and differentiation of pancreatic beta cells. Growth-promoting actions of BTC are mediated by epidermal growth factor receptors (ErbBs), namely ErbB-1, ErbB-2, ErbB-3 and ErbB-4; however, the exact mechanism for beta cell proliferation has not been elucidated. Therefore, we investigated which ErbBs are involved and some molecular mechanisms by which BTC regulates beta cell proliferation. METHODOLOGY/PRINCIPAL FINDINGS: The expression of ErbB-1, ErbB-2, ErbB-3, and ErbB-4 mRNA was detected by RT-PCR in both a beta cell line (MIN-6 cells) and C57BL/6 mouse islets. Immunoprecipitation and western blotting analysis showed that BTC treatment of MIN-6 cells induced phosphorylation of only ErbB-1 and ErbB-2 among the four EGF receptors. BTC treatment resulted in DNA synthetic activity, cell cycle progression, and bromodeoxyuridine (BrdU)-positive staining. The proliferative effect was blocked by treatment with AG1478 or AG825, specific tyrosine kinase inhibitors of ErbB-1 and ErbB-2, respectively. BTC treatment increased mRNA and protein levels of insulin receptor substrate-2 (IRS-2), and this was blocked by the ErbB-1 and ErbB-2 inhibitors. Inhibition of IRS-2 by siRNA blocked cell cycle progression induced by BTC treatment. Streptozotocin-induced diabetic mice injected with a recombinant adenovirus expressing BTC and treated with AG1478 or AG825 showed reduced islet size, reduced numbers of BrdU-positive cells in the islets, and did not attain BTC-mediated remission of diabetes. CONCLUSIONS/SIGNIFICANCE: These results suggest that BTC exerts proliferative activity on beta cells through the activation of ErbB-1 and ErbB-2 receptors, which may increase IRS-2 expression, contributing to the regeneration of beta cells

    High-throughput peptide quantification using mTRAQ reagent triplex

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    <p>Abstract</p> <p>Background</p> <p>Protein quantification is an essential step in many proteomics experiments. A number of labeling approaches have been proposed and adopted in mass spectrometry (MS) based relative quantification. The mTRAQ, one of the stable isotope labeling methods, is amine-specific and available in triplex format, so that the sample throughput could be doubled when compared with duplex reagents.</p> <p>Methods and results</p> <p>Here we propose a novel data analysis algorithm for peptide quantification in triplex mTRAQ experiments. It improved the accuracy of quantification in two features. First, it identified and separated triplex isotopic clusters of a peptide in each full MS scan. We designed a schematic model of triplex overlapping isotopic clusters, and separated triplex isotopic clusters by solving cubic equations, which are deduced from the schematic model. Second, it automatically determined the elution areas of peptides. Some peptides have similar atomic masses and elution times, so their elution areas can have overlaps. Our algorithm successfully identified the overlaps and found accurate elution areas. We validated our algorithm using standard protein mixture experiments.</p> <p>Conclusions</p> <p>We showed that our algorithm was able to accurately quantify peptides in triplex mTRAQ experiments. Its software implementation is compatible with Trans-Proteomic Pipeline (TPP), and thus enables high-throughput analysis of proteomics data.</p

    Electro-optical sampling of single-cycle Thz fields with single-photon detectors

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    Electro-optical sampling of Terahertz fields with ultrashort pulsed probes is a well-established approach for directly measuring the electric field of THz radiation. This technique usually relies on balanced detection to record the optical phase shift brought by THz-induced birefringence. The sensitivity of electro-optical sampling is, therefore, limited by the shot noise of the probe pulse, and improvements could be achieved using quantum metrology approaches using, e.g., NOON states for Heisenberg-limited phase estimation. We report on our experiments on THz electro-optical sampling using single-photon detectors and a weak squeezed vacuum field as the optical probe. Our approach achieves field sensitivity limited by the probe state statistical properties using phase-locked single-photon detectors and paves the way for further studies targeting quantum-enhanced THz sensing

    Observation of tW production in the single-lepton channel in pp collisions at root s=13 TeV

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    A measurement of the cross section of the associated production of a single top quark and a W boson in final states with a muon or electron and jets in proton-proton collisions at root s = 13 TeV is presented. The data correspond to an integrated luminosity of 36 fb(-1) collected with the CMS detector at the CERN LHC in 2016. A boosted decision tree is used to separate the tW signal from the dominant t (t) over bar background, whilst the subleading W+jets and multijet backgrounds are constrained using data-based estimates. This result is the first observation of the tW process in final states containing a muon or electron and jets, with a significance exceeding 5 standard deviations. The cross section is determined to be 89 +/- 4 (stat) +/- 12 (syst) pb, consistent with the standard model.Peer reviewe

    Numerical Investigation on the Effects of Baffles with Various Thermal and Geometrical Conditions on Thermo-Fluid Dynamics and Kinetic Power of a Solar Updraft Tower

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    Solar updraft towers (SUTs) are used for renewable power generation, taking advantage of the thermal updraft air flow caused by solar energy. Aerodynamic devices have been applied to SUTs to improve their performance and the baffle is one such device. Here, we investigate the effect of baffle installation on the thermo-fluid dynamic phenomena in the collector of an SUT and how it enhances the overall SUT performance using computational fluid dynamics analysis. Two geometric parameters (height and width of baffle) and two thermal boundary conditions of the baffle (adiabatic condition and heat flux condition) were tested through simulations with 10 different models. The vortex generated by the baffle has a positive effect on the delivery of heat energy from the ground to the main flow; however, one disadvantage is that the baffle inherently increases the resistance of the main flow. Over 3% higher kinetic power was achieved with some of the simulated baffle models. Therefore, an optimum design for baffle installation can be achieved by considering the positive and negative thermo-fluid dynamics of baffles

    The complete chloroplast genome of the moss, Myurella julacea (Schwägr.) Schimp. (Bryidae, Pterigynandraceae)

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    Here, we report the complete chloroplast (cp) genome of the moss Myurella julacea (Schwägr.) Schimp. We found that the total length of the M. julacea complete cp genome was 124,457 base pairs (bp) long, comprising 82 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. The genome had a typical quadripartite structure, and consisted of a large single-copy region (LSC) of 86,607 bp, a small single-copy region (SSC) of 18,508 bp, and a pair of inverted repeats with a length of 9671 bp each. The base composition of the cp DNA was 26.0% A, 29.4% T, 24.5% C, and 20.1% G with an overall GC content of 44.6%. Phylogenetic analysis revealed that M. julacea clustered into a clade with other Hypnales groups with high bootstrap support. The complete cp genome presented here will provide useful information for phylogenetic and evolutionary studies of endangered Bryophyte species

    The complete chloroplast genome of a moss Korea Bartramia pomiformis Hedw.

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    The complete chloroplast genome sequence of Bartramia pomiformis, a species of moss in the Bartramiaceae family, was determined using Illumina HiSeq paired-end sequencing data. The total size of the chloroplast genome of this species was 125,866 bp, and it contained a large single-copy (LSC) region of 87,214 bp, a small single-copy (SSC) region of 18,651 bp, and a pair of identical inverted repeat regions (IRs) of 10,014 bp. The genome contained 82 protein-coding genes, 36 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. The information of the B. pomiformis chloroplast genome will be valuable for evolutionary studies of the Bartramiaceae
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