4,630 research outputs found

    String Representation of Quantum Loops

    Get PDF
    We recover a general representation for the quantum state of a relativistic closed line (loop) in terms of string degrees of freedom.The general form of the loop functional splits into the product of the Eguchi functional, encoding the holographic quantum dynamics, times the Polyakov path integral, taking into account the full Bulk dynamics, times a loop effective action, which is needed to renormalize boundary ultraviolet divergences. The Polyakov string action is derived as an effective actionfrom a phase space,covariant,Schild action, by functionally integrating out the world-sheet coordinates.The area coordinates description of the boundary quantum dynamics, is shown to be induced by the ``zero mode'' of the bulk quantum fluctuations. Finally, we briefly comment about a ``unified, fully covariant'' description of points, loops and strings in terms of Matrix Coordinates.Comment: 16 Pages, RevTeX, no figure

    On the large N limit, W_\infty Strings, Star products, AdS/CFT Duality, Nonlinear Sigma Models on AdS spaces and Chern-Simons p-branes

    Full text link
    It is shown that the large NN limit of SU(N) YM in curvedcurved mm-dim backgrounds can be subsumed by a higher m+nm+n dimensional gravitational theory which can be identified to an mm-dim generally invariant gauge theory of diffs NN, where NN is an nn-dim internal space (Cho, Sho, Park, Yoon). Based on these findings, a very plausible geometrical interpretation of the AdS/CFTAdS/CFT correspondence could be given. Conformally invariant sigma models in D=2nD=2n dimensions with target non-compact SO(2n,1) groups are reviewed. Despite the non-compact nature of the SO(2n,1), the classical action and Hamiltonian are positive definite. Instanton field configurations are found to correspond geometrically to conformal ``stereographic'' mappings of R2nR^{2n} into the Euclidean signature AdS2nAdS_{2n} spaces. The relation between Self Dual branes and Chern-Simons branes, High Dimensional Knots, follows. A detailed discussion on WW_\infty symmetry is given and we outline the Vasiliev procedure to construct an action involving higher spin massless fields in AdS4AdS_4. This AdS4AdS_4 spacetime higher spin theory should have a one-to-one correspondence to noncritical WW_\infty strings propagating on AdS4×S7AdS_4 \times S^7.Comment: 43 pages, Tex fil

    Thermoelectric Figure of Merit of Strongly Correlated Superlattice Semiconductors

    Full text link
    We solved the Anderson Lattice Hamiltonian to get the energy bands of a strongly correlated semiconductor by using slave boson mean field theory. The transport properties were calculated in the relaxation-time approximation,and the thermoelectric figure of merit was obtained for the strongly correlated semiconductor and its superlattice structures. We found that at room temperature ZTZT can reach nearly 2 for the quantum wire lattice structure.We believe that it is possible to find high values of thermoelectric figure of merit from strongly correlated semiconductor superlattice systems.Comment: 4 pages, 3 figure

    Optimization of a Multiple Injection System in a Marine Diesel Engine through a Multiple-Criteria Decision-Making Approach

    Get PDF
    [Abstract] In this work, a numerical model was developed to analyze the performance and emissions of a marine diesel engine, the Wärtsilä 6L 46. This model was validated using experimental measurements and was employed to analyze several pre-injection parameters such as pre-injection rate, duration, and starting instant. The modification of these parameters may lead to opposite effects on consumption and/or emissions of nitrogen oxides (NOₓ), carbon monoxide (CO), and hydrocarbons (HC). According to this, the main goal of the present work is to employ a multiple-criteria decision-making (MCDM) approach to characterize the most appropriate injection pattern. Since determining the criteria weights significantly influences the overall result of a MCDM problem, a subjective weighting method was compared with four objective weighting methods: entropy, CRITIC (CRiteria Importance Through Intercriteria Correlation), variance, and standard deviation. The results showed the importance of subjectivism over objectivism in MCDM analyses. The CRITIC, variance, and standard deviation methods assigned more importance to NOₓ emissions and provided similar results. Nevertheless, the entropy method assigned more importance to consumption and provided a different injection pattern

    Bronchial provocation tests using methacholine, cycle ergometer exercise and free running in children with intermittent asthma

    Get PDF
    OBJECTIVE: To compare airway responsiveness to methacholine, cycle ergometer exercise and free running in children with intermittent asthma. METHODS: A randomized study was conducted with 30 children of both genders with intermittent asthma. Each child was submitted to challenge testing on three separate days, in random order: a) Methacholine challenge using a dosimeter; b) Exercise challenge testing - free running along a 50-meter-long corridor; c) Dry-air exercise challenge on a cycle ergometer. Target heart rate during exercise was 80 to 90% of the maximum predicted value. Spirometry was performed 3, 6,10,15,20 and 30 minutes after exercise. Exercise-induced bronchospasm was defined as a decrease in FEV1 of >10% in comparison to pretest values. RESULTS: Mean age was 11±3 years. FEV1 and FEV1/FVC ratios were normal and similar before all provocation tests. The maximum heart rate was 178±7 bpm during cycling and 181±6 bpm during the free running test (p > 0.05). Significant bronchospasm was observed with methacholine in 23 cases, after free running in 19 and after cycling in 14 children (p 10% em relação aos valores pré-teste. RESULTADOS: A média de idade foi 11±3 anos. O VEF1 e VEF1/CVF (capacidade vital forçada) foram normais e similares antes dos três testes de broncoprovocação. A freqüência cardíaca máxima foi de 178±7 bpm durante o exercício na bicicleta e 181±6 bpm na corrida livre (p > 0,05). Broncoespasmo significante foi visto em 23 crianças após o teste com metacolina, em 19 após a corrida livre e em 14 crianças após exercício em bicicleta (p < 0,05, metacolina versus testes de exercício). Levando-se em conta todas as medidas de VEF1 após o exercício, a corrida livre resultou em maior broncoespasmo em relação à bicicleta ergométrica (p = 0,003, chi2 = 8,948). Houve significante porém fraca correlação entre a queda máxima de VEF1 após a corrida livre e bicicleta (r = 0,46, p < 0,01). CONCLUSÕES: A broncoprovocação com metacolina identifica um maior número de asmáticos quando comparada aos testes de exercício. Quando a broncoprovocação com metacolina não estiver disponível, a corrida livre deve ser o teste de escolha, devido à sua simplicidade e maior capacidade de induzir broncoespasmo.Hospital do Servidor Público Estadual Francisco Morato de OliveiraUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP, EPMSciEL

    Panel Flutter Analysis and Optimization of Composite Tow Steered Plates

    Full text link
    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143015/1/6.2017-1118.pd

    Prothymosin α is phosphorylated by casein kinase-2

    Get PDF
    AbstractProthymosin α (ProTα) is a 12.5 kDa acidic polypeptide that is considered to have a nuclear function related to cell proliferation. Inspection of its amino acid sequence revealed the presence of sequences that may serve as targets for phosphorylation by casein kinase-2 (CK-2). ProTα isolated from calf thymocytes was phosphorylated in vitro by CK-2. The phosphorylation sites are Ser and Thr residues located among the first 14 amino acid residues in the ProTα sequence. Another site that is theoretically suitable for phosphorylation by CK-2, at the C-terminus of the polypeptide, is not, in fact, phosphorylated. Thymosin α1 (Tα1), a peptide whose sequence corresponds to the first 28 amino acids of ProTα, is also phosphorylated by CK-2 at the same phosphorylation sites as ProTα. In cultured splenic lymphocytes ProTα was phosphorylated at Thr residues located at positions 7, 12 and/or 13. Based on these observations we conclude that CK-2, or another cellular kinase with similar sequence specifity, is responsible for phosphorylation of ProTα in vivo

    Data Processing on Large Interdependent Networks: An Application for Infrastructure Preparedness, and Restoration

    Get PDF
    This paper presents a method for validating and transforming data for use in interdependent infrastructure network analysis. Critical infrastructure are interdependent on each other for delivery of services and execution of restoration activities.  These interdependencies make infrastructure systems vulnerable to extreme events and highlights the needs for preparedness and response plans.  Optimization models have been used to create effective plans using interdependent infrastructure networks.  These models require accurate input data.  However, many data sources have inconsistencies or errors which inhibit the ability to use such optimization models.   This work identifies common errors in input network data and provides a method for processing and correcting these errors.  We demonstrate the effectiveness of this method on data representing the transportation network in Juan Diaz town, in Panama. Keywords: Data processing, network, infrastructure, interdependence
    corecore