744 research outputs found

    On the Phase Transition of Conformal Field Theories with Holographic Duals

    Full text link
    We study the thermodynamic relations of conformal field theories (CFTs), which are holographically dual to anti-de Sitter-Schwarzschild bulk space-times. A Cardy-Verlinde formula is derived thermodynamically for CFTs living on S^n x R with S^n having an arbitrary radius. The Hawking-Page phase transition of the CFT is described using Landau's theory of phase transitions, and an alternative derivation of the Cardy-Verlinde formula is presented. The condensate in the high temperature phase is identified as being composed of radiational matter.Comment: 10 pages, final version to appear on PL

    Prescriptions for Off-Shell Bosonic String Amplitudes

    Get PDF
    We give, in the framework of the bosonic string theory, simple prescriptions for computing, at tree and one-loop levels, off-shell string amplitudes for open and closed string massless states. In particular we obtain a tree amplitude for three open strings that in the field theory limit coincides with the three-gluon vertex in the usual covariant gauge and two-string one-loop amplitudes satisfying the property of transversality.Comment: 11 pages, LaTeX, to appear in the proceedings of the workshop "Quantum Aspects of Gauge Theories, Supersymmetry and Unification", Corfu (Greece), 20-26 September 1998. Eq. (12) and numerical factors in eqs. (13) and (16) corrected; some minor changes and references adde

    Quality of Web Mashups: A Systematic Mapping Study

    Full text link
    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-04244-2_8Web mashups are a new generation of applications based on the composition of ready-to-use, heterogeneous components. They are gaining momentum thanks to their lightweight composition approach, which represents a new opportunity for companies to leverage on past investments in SOA, Web services, and public APIs. Although several studies are emerging in order to address mashup development, no systematic mapping studies have been reported on how quality issues are being addressed. This paper reports a systematic mapping study on which and how the quality of Web mashups has been addressed and how the product quality-aware approaches have been defined and validated. The aim of this study is to provide a background in which to appropriately develop future research activities. A total of 38 research papers have been included from an initial set of 187 papers. Our results provided some findings regarding how the most relevant product quality characteristics have been addressed in different artifacts and stages of the development process. They have also been useful to detect some research gaps, such as the need of more controlled experiments and more quality-aware mashup development proposals for other characteristics which being important for the Web domain have been neglected such as Usability and ReliabilityThis work is funded by the MULTIPLE project (TIN2009-13838), the Senescyt program (scholarships 2011), and the Erasmus Mundus Programme of the European Commission under the Transatlantic Partnership for Excellence in Engineering - TEE Project.Cedillo Orellana, IP.; Fernández Martínez, A.; Insfrán Pelozo, CE.; Abrahao Gonzales, SM. (2013). Quality of Web Mashups: A Systematic Mapping Study. En Current Trends in Web Engineering. Springer. 66-78. https://doi.org/10.1007/978-3-319-04244-2_8S6678Alkhalifa, E.: The Future of Enterprise Mashups. Business Insights. E-Strategies for Resource Management Systems (2009)Beemer, B., Gregg, D.: Mashups: A Literature Review and Classification Framework. Future Internet 1, 59–87 (2009)Cappiello, C., Daniel, F., Matera, M.: A Quality Model for Mashup Components. In: Gaedke, M., Grossniklaus, M., Díaz, O. (eds.) ICWE 2009. LNCS, vol. 5648, pp. 236–250. Springer, Heidelberg (2009)Cappiello, C., Daniel, F., Matera, M., Pautasso, C.: Information Quality in Mashups. IEEE Internet Computing 14(4), 32–40 (2010)Cappiello, C., Matera, M., Picozzi, M., Daniel, F., Fernandez, A.: Quality-Aware Mashup Composition: Issues, Techniques and Tools. In: 8th International Conference on the Quality of Information and Communications Technology (QUATIC 2012), pp. 10–19 (2012)Fenton, N.E., Pfleeger, S.L.: Software Metrics: A Rigorous and Practical Approach, 2nd edn. International Thompson 1996, pp. I–XII, 1–638 (1996) ISBN 978-1-85032-275-7Fernandez, A., Insfran, E., Abrahão, S.: Usability evaluation methods for the web: A systematic mapping study. Information and Software Technology 53(8), 789–817 (2011)Garousi, V., Mesbah, A., Betin-Can, A., Mirshokraie, S.: A systematic mapping study of web application testing. Information and Software Technology 55(8), 1374–1396 (2013)Grammel, L., Storey, M.-A.: A survey of mashup development environments. In: Chignell, M., Cordy, J., Ng, J., Yesha, Y. (eds.) The Smart Internet. LNCS, vol. 6400, pp. 137–151. Springer, Heidelberg (2010)Hoyer, V., Fischer, M.: Market Overview of Enterprise Mashup Tools. In: Bouguettaya, A., Krueger, I., Margaria, T. (eds.) ICSOC 2008. LNCS, vol. 5364, pp. 708–721. Springer, Heidelberg (2008)ISO/IEC: ISO/IEC 25010 Systems and software engineering. Systems and software Quality Requirements and Evaluation (SQuaRE). System and software quality models (2011)Kitchenham, B., Charters, S.: Guidelines for performing Systematic Literature Reviews in Software Engineering. Version 2.3, ESBE Technical Report, Keele University, UK (2007)Mendes, E.: A systematic review on the Web engineering research. In: International Symposium on Empirical Software Engineering (ISESE 2005), pp. 498–507 (2005)OrangeLabs: State of the Art in Mashup tools, SocEDA project, pp. 1–59 (2011)Petersen, K., Feldt, R., Mujtaba, S., Mattsson, M.: Systematic mapping studies in software engineering. In: 12th International Conference on Evaluation and Assessment in Software Engineering (EASE), pp. 68–77 (2008)Raza, M., Hussain, F.K., Chang, E.: A methodology for quality-based mashup of data sources. In: 10th International Conference on Information Integration and Web-based Applications & Services (iiWAS 2008), pp. 528–533 (2008)Saeed, A.: A Quality-based Framework for Leveraging the Process of Mashup Component Selection (2009), https://gupea.ub.gu.se/handle/2077/21953Sharma, A., Hellmann, T.D., Maurer, F.: Testing of Web Services - A Systematic Mapping. In: 8th World Congress on Services (SERVICES 2012), pp. 346–352 (2012

    Off-shell amplitudes for nonoriented closed strings

    Get PDF
    In the context of the bosonic closed string theory, by using the operatorial formalism, we give a simple expression of the off-shell amplitude with an arbitrary number of external massless states inserted on the Klein bottle

    Antipseudomonal and immunomodulatory properties of esc peptides: Promising features for treatment of chronic infectious diseases and inflammation

    Get PDF
    Persistent infections, such as those provoked by the Gram-negative bacterium Pseudomonas aeruginosa in the lungs of cystic fibrosis (CF) patients, can induce inflammation with lung tissue damage and progressive alteration of respiratory function. Therefore, compounds having both an-timicrobial and immunomodulatory activities are certainly of great advantage in fighting infectious diseases and chronic inflammation. We recently demonstrated the potent antipseudomonal efficacy of the antimicrobial peptide (AMP) Esc(1-21) and its diastereomer Esc(1-21)-1c, namely Esc peptides. Here, we confirmed this antimicrobial activity by reporting on the peptides’ ability to kill P. aeruginosa once internalized into alveolar epithelial cells. Furthermore, by means of enzyme-linked immunosor-bent assay and Western blot analyses, we investigated the peptides’ ability to detoxify the bacterial lipopolysaccharide (LPS) by studying their effects on the secretion of the pro-inflammatory cytokine IL-6 as well as on the expression of cyclooxygenase-2 from macrophages activated by P. aeruginosa LPS. In addition, by a modified scratch assay we showed that both AMPs are able to stimulate the closure of a gap produced in alveolar epithelial cells when cell migration is inhibited by concentrations of Pseudomonas LPS that mimic lung infection conditions, suggesting a peptide-induced airway wound repair. Overall, these results have highlighted the two Esc peptides as valuable candidates for the development of new multifunctional therapeutics for treatment of chronic infectious disease and inflammation, as found in CF patients

    Generating Functional for Strong and Nonleptonic Weak Interactions

    Full text link
    The generating functional for Green functions of quark currents is given in closed form to next-to-leading order in the low-energy expansion for chiral SU(3), including one-loop amplitudes with up to three meson propagators. Matrix elements and form factors for strong and nonleptonic weak processes with at most six external states can be extracted from this functional by performing three-dimensional flavour traces. To implement this procedure, a Mathematica program is provided that evaluates amplitudes with at most six external mesons, photons (real or virtual) and virtual W (semileptonic form factors). The program is illustrated with several examples that can be compared with existing calculations.Comment: 26 pages; references added, comparison with other programs added, small changes in the text, version to appear in JHE

    The Gabor wave front set of compactly supported distributions

    Full text link
    We show that the Gabor wave front set of a compactly supported distribution equals zero times the projection on the second variable of the classical wave front set

    A holographic approach to low-energy weak interactions of hadrons

    Full text link
    We apply the double-trace formalism to incorporate nonleptonic weak interactions of hadrons into holographic models of the strong interactions. We focus our attention upon ΔS=1\Delta S=1 nonleptonic kaon decays. By working with a Yang-Mills--Chern-Simons 5-dimensional action, we explicitly show how, at low energies, one recovers the ΔS=1\Delta S=1 weak chiral Lagrangian for both the anomalous and nonanomalous sectors. We provide definite predictions for the low energy coefficients in terms of the AdS metric and argue that the double-trace formalism is a 5-dimensional avatar of the Weak Deformation Model introduced long ago by Ecker et al. As a significant phenomenological application, we reassess the K→3πK\to 3\pi decays in the light of the holographic model. Previous models found a fine-tuned cancellation of resonance exchange in these decays, which was both conceptually puzzling and quantitatively in disagreement with experimental results. The holographic model we build is an illustrative counterexample showing that the cancellation encountered in the literature is not generic but a model-dependent statement and that agreement with experiment can be obtained.Comment: 20 page

    The antimicrobial peptide temporin G: Anti-biofilm, anti-persister activities, and potentiator effect of tobramycin efficacy against Staphylococcus aureus

    Get PDF
    Bacterial biofilms are a serious threat for human health, and the Gram-positive bacterium Staphylococcus aureus is one of the microorganisms that can easily switch from a planktonic to a sessile lifestyle, providing protection from a large variety of adverse environmental conditions. Dormant non-dividing cells with low metabolic activity, named persisters, are tolerant to antibiotic treatment and are the principal cause of recalcitrant and resistant infections, including skin infections. Antimicrobial peptides (AMPs) hold promise as new anti-infective agents to treat such infections. Here for the first time, we investigated the activity of the frog-skin AMP temporin G (TG) against preformed S. aureus biofilm including persisters, as well as its efficacy in combination with tobramycin, in inhibiting S. aureus growth. TG was found to provoke ~50 to 100% reduction of biofilm viability in the concentration range from 12.5 to 100 µM vs ATCC and clinical isolates and to be active against persister cells (about 70–80% killing at 50–100 µM). Notably, sub-inhibitory concentrations of TG in combination with tobramycin were able to significantly reduce S. aureus growth, potentiating the antibiotic power. No critical cytotoxicity was detected when TG was tested in vitro up to 100 µM against human keratinocytes, confirming its safety profile for the development of a new potential anti-infective drug, especially for treatment of bacterial skin infections

    Vector-meson contributions do not explain the rate and spectrum in K_L -> pi0 gamma gamma

    Full text link
    We analyze the recent NA48 data for the reaction K_L -> pi0 gamma gamma with and without the assumption of vector meson dominance (VMD). We find that the data is well described by a three-parameter expression inspired by O(p^6) chiral perturbation theory. We also find that it is impossible to fit the shape of the decay distribution and the overall rate simultaneously if one imposes the VMD constraints on the three parameters. We comment on the different fits and their implications for the CP-conserving component of the decay K_L -> pi0 e+ e-.Comment: Version accepted for publication on Phys. Rev. D. 19 pages, LaTeX, 8 figures, uses epsf.st
    • …
    corecore