4,060 research outputs found

    Investigation of the tetraquark candidate a0(980)a_0(980): technical aspects and preliminary results

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    We discuss technical aspects and first results of a lattice QCD study of the a0(980)a_0(980) state. We employ various interpolating operators of quark-antiquark, mesonic molecule, diquark-antidiquark and two-meson type. Both connected and disconnected contributions including diagrams with closed fermion loops are computed. To keep statistical errors small, it is essential to optimize the computation of these diagrams by choosing that combination of techniques most appropriate for each type of diagram from the correlation matrix of interpolating operators. We illustrate, how this can be done, by discussing certain diagrams in detail. We also present preliminary results corresponding to a 4×44\times 4 submatrix computed with 2+1 flavors of clover fermions.Comment: 13 pages, 9 figures, talks given at the 32nd International Symposium on Lattice Field Theory (Lattice 2014), 23-28 June 2014, Columbia University, New York, NY, US

    Computation of correlation matrices for tetraquark candidates with JP=0+J^P = 0^+ and flavor structure q1q2ˉq3qˉ3q_1 \bar{q_2} q_3 \bar{q}_3

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    The conjecture that several recently observed mesons have a structure, which is not dominated by an ordinary quark-antiquark pair, but by a four-quark structure, is being actively investigated both theoretical and experimentally. Such a state may be characterized as a mesonic molecule or as a diquark-antidiquark pair. Lattice QCD provides a theoretically sound framework to study such states. To quantitatively investigate the internal structure of such mesons, one needs to precisely compute correlation matrices containing several interpolating operators including two and four quarks. Here we discuss certain technical aspects of such correlation matrices suited to study tetraquark candidates with JP=0+J^P = 0^+ and flavor structure q1q2ˉq3qˉ3q_1 \bar{q_2} q_3 \bar{q}_3, e.g.\ the a0(980)a_0(980) meson, the Ds0D_{s0}^\ast meson and some of the charged ccˉc \bar{c} XX states. Some numerical results for the a0(980)a_0(980) meson are presented.Comment: 7 pages, 4 figures, talk given at the 33rd International Symposium on Lattice Field Theory (Lattice 2015), 14-18 July 2015, Kobe International Conference Center, Kobe, Japa

    Careful Whisper -- leveraging advances in automatic speech recognition for robust and interpretable aphasia subtype classification

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    This paper presents a fully automated approach for identifying speech anomalies from voice recordings to aid in the assessment of speech impairments. By combining Connectionist Temporal Classification (CTC) and encoder-decoder-based automatic speech recognition models, we generate rich acoustic and clean transcripts. We then apply several natural language processing methods to extract features from these transcripts to produce prototypes of healthy speech. Basic distance measures from these prototypes serve as input features for standard machine learning classifiers, yielding human-level accuracy for the distinction between recordings of people with aphasia and a healthy control group. Furthermore, the most frequently occurring aphasia types can be distinguished with 90% accuracy. The pipeline is directly applicable to other diseases and languages, showing promise for robustly extracting diagnostic speech biomarkers

    Neural Volumetric Blendshapes: Computationally Efficient Physics-Based Facial Blendshapes

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    Computationally weak systems and demanding graphical applications are still mostly dependent on linear blendshapes for facial animations. The accompanying artifacts such as self-intersections, loss of volume, or missing soft tissue elasticity can be avoided by using physics-based animation models. However, these are cumbersome to implement and require immense computational effort. We propose neural volumetric blendshapes, an approach that combines the advantages of physics-based simulations with realtime runtimes even on consumer-grade CPUs. To this end, we present a neural network that efficiently approximates the involved volumetric simulations and generalizes across human identities as well as facial expressions. Our approach can be used on top of any linear blendshape system and, hence, can be deployed straightforwardly. Furthermore, it only requires a single neutral face mesh as input in the minimal setting. Along with the design of the network, we introduce a pipeline for the challenging creation of anatomically and physically plausible training data. Part of the pipeline is a novel hybrid regressor that densely positions a skull within a skin surface while avoiding intersections. The fidelity of all parts of the data generation pipeline as well as the accuracy and efficiency of the network are evaluated in this work. Upon publication, the trained models and associated code will be released

    Lattice investigation of the tetraquark candidates a0(980) and kappa

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    It is a long discussed issue whether light scalar mesons have sizeable four-quark components. We present an exploratory study of this question using Nf = 2+1+1 twisted mass lattice QCD. A mixed action approach ignoring disconnected contributions is used to calculate correlatormatrices consisting of mesonic molecule, diquark-antidiquark and two-meson interpolating operators with quantum numbers of the scalar mesons a0(980) (1(0++)) and k (1/2(0+)). The correlation matrices are analyzed by solving the generalized eigenvalue problem. The theoretically expected free two-particle scattering states are identified, while no additional low lying states are observed. We do not observe indications for bound four-quark states in the channels investigated

    O MARKETING NO ENSINO SUPERIOR: COMPARATIVO BRASIL-PORTUGAL

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    Ao abordar o marketing aplicado ao ensino superior, este estudo tem como objectivos discutir os conceitos teóricos do marketing educacional e aplicá-los aos contextos brasileiro e português. Tendo em consideração que o marketing educacional tem a sua maior expressão nos E.U.A., a sua aplicação a diferentes realidades e culturas requer adaptações. Inicialmente, fez-se uma revisão dos conceitos tradicionais de marketing educacional, com ênfase no marketing-mix aplicado à educação. Posteriormente realizou-se uma caracterização dos contextos actuais do ensino superior no Brasil e em Portugal, e fez-se uma comparação da aplicação do marketing educacional nas realidades brasileira e portuguesa, focando as análises no marketing-mix educacional. Percebeu-se que o ensino superior no Brasil tem características muito diversas do ensino superior em Portugal e ambos divergem na aplicação dos conceitos mais tradicionais do marketing à educação. Desta forma, faz-se necessária a construção de abordagens teóricas específicas para a aplicação do marketing educacional a diferentes nações

    Portuguese state university performance according to students: an efficiency analysis

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    The objective of this research project is to evaluate the performance of Portuguese state universities in accordance with the expectations and satisfactions of their students and through recourse to the DEA methodology and thus representing one of the very few studies analysing university performance based upon student perceptions. According to an output oriented Variable Returns to Scale model, handling the responses returned by 1,669 students, the results demonstrate that faculties generally attain a good relationship between student expectations and their levels of satisfaction. We furthermore conclude that university scale does not guarantee efficiency. Hence, irrespective of size, universities are able to ensure the satisfaction of their students. Finally, the results show that satisfying only certain expectations related to specific aspects does not prove sufficient to guaranteeing overall student satisfaction. The analysis also correspondingly finds that while some decision making units prove efficient in satisfying expectations on specific aspects, they fail to attain such efficiency in the overall perspective of students
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