2,302 research outputs found

    A Numerical Model Calculation of the Flow in DeSoto Canyon in Response to Northerly Wind Bursts in Winter

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    The continental shelf currents observed at the head of DeSoto Canyon offshore of Pensacola, FL, during Nov, 1997-Feb. 1998, are studied with the aid of a Bryan-Cox model of the entire Gulf of Mexico. The basic model circulation with no winds features a Loop Current and a weak flow in DeSoto Canyon. In contrast, the model response to northerly wind bursts produces strong canyon currents. Wind-driven southward currents on the West Florida Shelf (WFS) appear to pull a strong flow around DeSoto Canyon, giving rise to a strong up-canyon flow on the west flank The wind-enhanced flow in DeSoto Canyon is reproduced with a model run that incorporates wind stresses derived from the NCEP-NCAR reanalysis winds for March 1997-April 1998. The model flow for the winter period (Nov. 1997-Feb. 1998) is compared with observed currents at three canyon-head locations in 100 m of water available from a Science Applications International Corporation mooring experiment. Model and observed velocities in the general around-canyon direction track each other reasonably well, with peaks synchronized roughly with but lagging slightly northerly wind bursts. The lag time appears consistent with the generation at Key West of first-mode continental shelf waves responsible for wind-driven alongshore currents on the WFS. Pressure gradient slightly in excess of that necessary for a geostrophic balance with the (eastward) alongshore flow appears to generate onshore flows, giving rise to midshelf upwelling after northerly wind bursts

    Charmed Baryon Weak Decays with SU(3) Flavor Symmetry

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    We study the semileptonic and non-leptonic charmed baryon decays with SU(3)SU(3) flavor symmetry, where the charmed baryons can be Bc=(Ξc0,Ξc+,Λc+){\bf B}_{c}=(\Xi_c^0,\Xi_c^+,\Lambda_c^+), Bc′=(Σc(++,+,0),Ξc′(+,0),Ωc0){\bf B}'_{c}=(\Sigma_c^{(++,+,0)},\Xi_{c}^{\prime(+,0)},\Omega_c^0), Bcc=(Ξcc++,Ξcc+,Ωcc+){\bf B}_{cc}=(\Xi_{cc}^{++},\Xi_{cc}^+,\Omega_{cc}^+), or Bccc=Ωccc++{\bf B}_{ccc}=\Omega^{++}_{ccc}. With Bn(′){\bf B}_n^{(\prime)} denoted as the baryon octet (decuplet), we find that the Bc→Bn′ℓ+νℓ{\bf B}_{c}\to {\bf B}'_n\ell^+\nu_\ell decays are forbidden, while the Ωc0→Ω−ℓ+νℓ\Omega_c^0\to \Omega^-\ell^+\nu_\ell, Ωcc+→Ωc0ℓ+νℓ\Omega_{cc}^+\to\Omega_c^0\ell^+\nu_\ell, and Ωccc++→Ωcc+ℓ+νℓ\Omega_{ccc}^{++}\to \Omega_{cc}^+\ell^+\nu_\ell decays are the only existing Cabibbo-allowed modes for Bc′→Bn′ℓ+νℓ{\bf B}'_{c}\to {\bf B}'_n\ell^+\nu_\ell, Bcc→Bc′ℓ+νℓ{\bf B}_{cc}\to {\bf B}'_c\ell^+\nu_\ell, and Bccc→Bcc(′)ℓ+νℓ{\bf B}_{ccc}\to {\bf B}_{cc}^{(\prime)}\ell^+\nu_\ell, respectively. We predict the rarely studied Bc→Bn(′)M{\bf B}_{c}\to {\bf B}_n^{(\prime)}M decays, such as B(Ξc0→Λ0Kˉ0, Ξc+→Ξ0π+)=(8.3±0.9,8.0±4.1)×10−3{\cal B}(\Xi_c^0\to\Lambda^0\bar K^0,\,\Xi_c^+\to\Xi^0\pi^+)=(8.3\pm 0.9,8.0\pm 4.1)\times 10^{-3} and B(Λc+→Δ++π−, Ξc0→Ω−K+)=(5.5±1.3,4.8±0.5)×10−3{\cal B}(\Lambda_c^+\to \Delta^{++}\pi^-,\,\Xi_c^0\to\Omega^- K^+)=(5.5\pm 1.3,4.8\pm 0.5)\times 10^{-3}. For the observation, the doubly and triply charmed baryon decays of Ωcc+→Ξc+Kˉ0\Omega_{cc}^{+}\to \Xi_c^+\bar K^0, Ξcc++→(Ξc+π+\Xi_{cc}^{++}\to (\Xi_c^+\pi^+, Σc++Kˉ0)\Sigma_c^{++}\bar K^0), and Ωccc++→(Ξcc++Kˉ0,Ωcc+π+,Ξc+D+)\Omega_{ccc}^{++}\to (\Xi_{cc}^{++}\bar K^0,\Omega_{cc}^+\pi^+,\Xi_c^+ D^+) are the favored Cabibbo-allowed decays, which are accessible to the BESIII and LHCb experiments.Comment: 29 pages, no figure, a typo in the table correcte

    Interface-induced heavy-hole/light-hole splitting of acceptors in silicon

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    The energy spectrum of spin-orbit coupled states of individual sub-surface boron acceptor dopants in silicon have been investigated using scanning tunneling spectroscopy (STS) at cryogenic temperatures. The spatially resolved tunnel spectra show two resonances which we ascribe to the heavy- and light-hole Kramers doublets. This type of broken degeneracy has recently been argued to be advantageous for the lifetime of acceptor-based qubits [Phys. Rev. B 88 064308 (2013)]. The depth dependent energy splitting between the heavy- and light-hole Kramers doublets is consistent with tight binding calculations, and is in excess of 1 meV for all acceptors within the experimentally accessible depth range (< 2 nm from the surface). These results will aid the development of tunable acceptor-based qubits in silicon with long coherence times and the possibility for electrical manipulation

    Generating Abstractive Summaries from Meeting Transcripts

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    Summaries of meetings are very important as they convey the essential content of discussions in a concise form. Generally, it is time consuming to read and understand the whole documents. Therefore, summaries play an important role as the readers are interested in only the important context of discussions. In this work, we address the task of meeting document summarization. Automatic summarization systems on meeting conversations developed so far have been primarily extractive, resulting in unacceptable summaries that are hard to read. The extracted utterances contain disfluencies that affect the quality of the extractive summaries. To make summaries much more readable, we propose an approach to generating abstractive summaries by fusing important content from several utterances. We first separate meeting transcripts into various topic segments, and then identify the important utterances in each segment using a supervised learning approach. The important utterances are then combined together to generate a one-sentence summary. In the text generation step, the dependency parses of the utterances in each segment are combined together to create a directed graph. The most informative and well-formed sub-graph obtained by integer linear programming (ILP) is selected to generate a one-sentence summary for each topic segment. The ILP formulation reduces disfluencies by leveraging grammatical relations that are more prominent in non-conversational style of text, and therefore generates summaries that is comparable to human-written abstractive summaries. Experimental results show that our method can generate more informative summaries than the baselines. In addition, readability assessments by human judges as well as log-likelihood estimates obtained from the dependency parser show that our generated summaries are significantly readable and well-formed.Comment: 10 pages, Proceedings of the 2015 ACM Symposium on Document Engineering, DocEng' 201

    Key Factors in the Medical Examination Product Design and Development Using Human Cell Image Totems

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    The industry of cultural creativity has a significant influence on the overall economy of a country. The development and application of cultural and creative products in different fields are growing more diverse. In the field of medicine, cultural and creative products can deliver more than aesthetic functions. They can bring healing benefits for patients with different symptoms in different age groups. Creative product designs that combine medicine and cultural/artistic creativity can make medical products warmer and friendlier to users. Focusing on the creative design of medical examination products, this study aims to provide references for more creative and friendly design of medical examination products to help reduce the fear and anxiety of patients when using such products. In this study, micro images of human cells are converted into totems as design elements for the design and development of cultural and creative products. These image totems not only represent the lively cellular world inside human body but also add aesthetics to the product design and make the products look warmer and friendlier to users. The research methods of literature survey, expert interview survey, and analytic hierarchy process (AHP) to first find out the factors in the medical product design using image totems of human cell mutation and reproduction and then measure the relative weight of each factor. Hopefully, the findings of this study can provide references for the creative design and development of medical examination products and help to enhance the design effectiveness. &nbsp; &nbsp; Keywords: cultural creativity industry, medical examination, products with healing effects, expert interview, analytic hierarchy process (AHP

    A Study on Tourism Development Strategy of Kaohsiung City in Taiwan after Urban Style Regeneration

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    Urban tourism has gradually been emphasized in past years; especially, it is regarded as a savior of urban regeneration in old industrial cities. When losing the competitive advantages and getting declined, old industrial cities are facing the challenge of transformation. The development of urban tourism is considered as the opportunity of industrial cities in dark recession that they start to involve in the development of tourism. Analytic Hierarchy Process (AHP) is applied in this study to evaluate key success factors in the tourism development strategy of Kaohsiung City after the urban style regeneration. AHP is used for confirming the levels of various evaluation factors. The first hierarchy contains four evaluation dimensions, and 14 evaluation standards are covered in the second hierarchy. The results reveal the important sequence of four evaluation factors in the second hierarchy as (1) marketing activity, (2) management strategy, (3) recreational environment, and (4) infrastructure, where the importance of evaluation factors in the third hierarchy is sequenced as (1) urban attraction, (2) environmental facility maintenance, (3) celebrations, (4) local characteristics, and (5) natural landscape. The research results and suggestions in this study are expected to enhance the tourism development of Kaohsiung City in Taiwan after the urban style regeneration. &nbsp; &nbsp; Keywords: urban style, tourism development strategy, key success factors, Delphi method, AH

    A Microcantilever-based Gas Flow Sensor for Flow Rate and Direction Detection

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    The purpose of this paper is to apply characteristics of residual stress that causes cantilever beams to bend for manufacturing a micro-structured gas flow sensor. This study uses a silicon wafer deposited silicon nitride layers, reassembled the gas flow sensor with four cantilever beams that perpendicular to each other and manufactured piezoresistive structure on each micro-cantilever by MEMS technologies, respectively. When the cantilever beams are formed after etching the silicon wafer, it bends up a little due to the released residual stress induced in the previous fabrication process. As air flows through the sensor upstream and downstream beam deformation was made, thus the airflow direction can be determined through comparing the resistance variation between different cantilever beams. The flow rate can also be measured by calculating the total resistance variations on the four cantilevers.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

    R-Curve Response Of Silicon Carbide Whisker-Reinforced Alumina: Microstructural Influence

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    Rising fracture resistance with crack extension (R-curve response) can lead to improvements in the mechanical reliability of ceramics. To understand how microstructures influence the R-curve behavior, direct observations of crack interactions with microstructural features were conducted on SiC whisker-reinforced alumina. The contribution of the dominant toughening mechanisms to the R-curve behavior of these composites is discussed using experimental and theoretical studies
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