461 research outputs found

    Electrochemical Synthesis of Thienoacene Derivatives: Transitionā€Metalā€Free Dehydrogenative Cāˆ’S Coupling Promoted by a Halogen Mediator

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    The first electrochemical dehydrogenative Cāˆ’S bond formation leading to thienoacene derivatives is described. Several thienoacene derivatives were synthesized by dehydrogenative Cāˆ’H/Sāˆ’H coupling. The addition of nBu4NBr, which catalytically promoted the reaction as a halogen mediator, was essential

    Entropy of Kaluza-Klein Black Hole from Kerr/CFT Correspondence

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    We extend the recently proposed Kerr/CFT correspondence to examine the dual conformal field theory of Kaluza-Klein black hole. For the extremal Kaluza-Klein black hole, the central charge and temperature of the dual conformal field are calculated, and the microscopic entropy calculated by using Cardy formula agrees with the Bekenstein-Hawking entropy of extremal Kaluza-Klein black hole. For the non-extremal case, we investigate the hidden conformal symmetry of Kaluza-Klein black hole by studying the near-region wave equation of a neutral massless scalar field, and find the left and right temperatures of dual conformal field theory. Furthermore, the entropy of non-extremal Kaluza-Klein black hole is reproduced by using Cardy formula.Comment: 13pages, no figure, published versio

    Holographic Dual of Linear Dilaton Black Hole in Einstein-Maxwell-Dilaton-Axion Gravity

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    Motivated by the recently proposed Kerr/CFT correspondence, we investigate the holographic dual of the extremal and non-extremal rotating linear dilaton black hole in Einstein-Maxwell-Dilaton-Axion Gravity. For the case of extremal black hole, by imposing the appropriate boundary condition at spatial infinity of the near horizon extremal geometry, the Virasoro algebra of conserved charges associated with the asymptotic symmetry group is obtained. It is shown that the microscopic entropy of the dual conformal field given by Cardy formula exactly agrees with Bekenstein-Hawking entropy of extremal black hole. Then, by rewriting the wave equation of massless scalar field with sufficient low energy as the SL(2, R)L_LƗ\timesSL(2, R)R_R Casimir operator, we find the hidden conformal symmetry of the non-extremal linear dilaton black hole, which implies that the non-extremal rotating linear dilaton black hole is holographically dual to a two dimensional conformal field theory with the non-zero left and right temperatures. Furthermore, it is shown that the entropy of non-extremal black hole can be reproduced by using Cardy formula.Comment: 15 pages, no figure, published versio

    A hierarchical and regional deep learning architecture for image description generation

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    This research proposes a distinctive deep learning network architecture for image captioning and description generation. Specifically, we propose a hierarchically trained deep network in order to increase the fluidity and descriptive nature of the generated image captions. The proposed deep network consists of initial regional proposal generation and two key stages for image description generation. The initial regional proposal generation is based upon the Region Proposal Network from the Faster R-CNN. This process generates regions of interest that are then used to annotate and classify human and object attributes. The first key stage of the proposed system conducts detailed label description generation for each region of interest. The second stage uses a Recurrent Neural Network (RNN)-based encoder-decoder structure to translate these regional descriptions into a full image description. Especially, the proposed deep network model can label scenes, objects, human and object attributes, simultaneously, which is achieved through multiple individually trained RNNs The empirical results indicate that our work is comparable to existing research and outperforms state-of-the-art existing methods considerably when evaluated with out-of-domain images from the IAPR TC-12 dataset, especially considering that our system is not trained on images from any of the image captioning datasets. When evaluated with several well-known evaluation metrics, the proposed system achieves an improvement of āˆ¼60% at BLEU-1 over existing methods on the IAPR TC-12 dataset. Moreover, compared with related methods, the proposed deep network requires substantially fewer data samples for training, leading to a much-reduced computational cost

    Two-dimensional universal conductance fluctuations and the electron-phonon interaction of topological surface states in Bi2Te2Se nanoribbons

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    The universal conductance fluctuations (UCFs), one of the most important manifestations of mesoscopic electronic interference, have not yet been demonstrated for the two-dimensional surface state of topological insulators (TIs). Even if one delicately suppresses the bulk conductance by improving the quality of TI crystals, the fluctuation of the bulk conductance still keeps competitive and difficult to be separated from the desired UCFs of surface carriers. Here we report on the experimental evidence of the UCFs of the two-dimensional surface state in the bulk insulating Bi2Te2Se nanoribbons. The solely-B\perp-dependent UCF is achieved and its temperature dependence is investigated. The surface transport is further revealed by weak antilocalizations. Such survived UCFs of the topological surface states result from the limited dephasing length of the bulk carriers in ternary crystals. The electron-phonon interaction is addressed as a secondary source of the surface state dephasing based on the temperature-dependent scaling behavior

    RIOJA. Complex Dusty Starbursts in a Major Merger B14-65666 at z=7.15

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    We present JWST NIRCam imaging of B14-65666 ("Big Three Dragons"), a bright Lyman-break galaxy system (MUV=āˆ’22.5M_\text{UV}=-22.5 mag) at z=7.15z=7.15. The high angular resolution of NIRCam reveals the complex morphology of two galaxy components: galaxy E has a compact core (E-core), surrounded by diffuse, extended, rest-frame optical emission, which is likely to be tidal tails; and galaxy W has a clumpy and elongated morphology with a blue UV slope (Ī²UV=āˆ’2.2Ā±0.1\beta_\text{UV}=-2.2\pm0.1). The flux excess, F356Wāˆ’-F444W, peaks at the E-core (1.05āˆ’0.09+0.081.05^{+0.08}_{-0.09} mag), tracing the presence of strong [OIII] 4960,5008 \r{A} emission. ALMA archival data show that the bluer galaxy W is brighter in dust continua than the redder galaxy E, while the tails are bright in [OIII] 88 Ī¼m\mathrm{\mu m}. The UV/optical and sub-mm SED fitting confirms that B14-65666 is a major merger in a starburst phase as derived from the stellar mass ratio (3:1 to 2:1) and the star-formation rate, ā‰ƒ1\simeq1 dex higher than the star-formation main sequence at the same redshift. The galaxy E is a dusty (AV=1.2Ā±0.1A_\text{V}=1.2\pm0.1 mag) starburst with a possible high dust temperature (ā‰„63\ge63-6868 K). The galaxy W would have a low dust temperature (ā‰¤27\le27-3333 K) or patchy stellar-and-dust geometry, as suggested from the infrared excess (IRX) and Ī²UV\beta_\text{UV} diagram. The high optical-to-FIR [OIII] line ratio of the E-core shows its lower gas-phase metallicity (ā‰ƒ0.2\simeq0.2 ZāŠ™_{\odot}) than the galaxy W. These results agree with a scenario where major mergers disturb morphology and induce nuclear dusty starbursts triggered by less-enriched inflows. B14-65666 shows a picture of complex stellar buildup processes during major mergers in the epoch of reionization.Comment: 18 pages, 6 figures, 4 tables. Submitted to Ap

    Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

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    We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

    Updated Measurements of [O iii] 88 Ī¼m, [C ii] 158 Ī¼m, and Dust Continuum Emission from a z = 7.2 Galaxy

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    We present updated measurements of the [O iii] 88 Ī¼m, [C ii] 158 Ī¼m, and dust continuum emission from a star-forming galaxy at z = 7.212, SXDF-NB1006-2, by utilizing Atacama Large Millimeter/submillimeter Array (ALMA) archival data sets analysed in previous studies and data sets that have not been analysed before. The follow-up ALMA observations with higher angular resolution and sensitivity reveal a clumpy structure of the [O iii] emission on a scale of 0.32-0.85 kpc. We also combined all the ALMA [O iii] ([C ii]) data sets and updated the [O iii] ([C ii]) detection to 5.9Ļƒ (3.6Ļƒ-4.5Ļƒ). The non-detection of [C ii] with data from the REBELS large program implies the incompleteness of spectral-scan surveys using [C ii] to detect galaxies with high star formation rates (SFRs) but marginal [C ii] emission at high-z. The dust continuum at 90 and 160 Ī¼m remains undetected, indicating little dust content of <3.9 Ɨ 106 M āŠ™ (3Ļƒ), and we obtained a more stringent constraint on the total infrared luminosity. We updated the [O iii]/[C ii] luminosity ratios to 10.2 Ā± 4.7 (6.1 Ā± 3.5) and 20 Ā± 12 (9.6 Ā± 6.1) for the 4.5Ļƒ and 3.6Ļƒ [C ii] detections, respectively, where the ratios in the parentheses are corrected for the surface brightness dimming effect on the extended [C ii] emission. We also found a strong [C ii] deficit (0.6-1.3 dex) between SXDF-NB1006-2 and the mean L [C II]āˆ’SFR relation of galaxies at 0 < z < 9

    O-GlcNAcylation and oxidation of proteins: is signalling in the cardiovascular system becoming sweeter?

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    O-GlcNAcylation is an unusual form of protein glycosylation, where a single-sugar [GlcNAc (N-acetylglucosamine)] is added (via Ī²-attachment) to the hydroxyl moiety of serine and threonine residues of nuclear and cytoplasmic proteins. A complex and extensive interplay exists between O-GlcNAcylation and phosphorylation. Many phosphorylation sites are also known glycosylation sites, and this reciprocal occupancy may produce different activities or alter the stability in a target protein. The interplay between these two post-translational modifications is not always reciprocal, as some proteins can be concomitantly phosphorylated and O-GlcNAcylated, and the adjacent phosphorylation or O-GlcNAcylation can regulate the addition of either moiety. Increased cardiovascular production of ROS (reactive oxygen species), termed oxidative stress, has been consistently reported in various chronic diseases and in conditions where O-GlcNAcylation has been implicated as a contributing mechanism for the associated organ injury/protection (for example, diabetes, Alzheimer's disease, arterial hypertension, aging and ischaemia). In the present review, we will briefly comment on general aspects of O-GlcNAcylation and provide an overview of what has been reported for this post-translational modification in the cardiovascular system. We will then specifically address whether signalling molecules involved in redox signalling can be modified by O-GlcNAc (O-linked GlcNAc) and will discuss the critical interplay between O-GlcNAcylation and ROS generation. Experimental evidence indicates that the interactions between O-GlcNAcylation and oxidation of proteins are important not only for cell regulation in physiological conditions, but also under pathological states where the interplay may become dysfunctional and thereby exacerbate cellular injury
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