149 research outputs found

    Importance of the logistics performance index in international trade

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    This is an author's accepted manuscript of an article published in: “Applied Economics"; Volume 46, Issue 24, 2014; copyright Taylor & Francis; available online at: http://dx.doi.org/10.1080/00036846.2014.916394Logistics and transport increasingly play a pivotal role in international trade relations. The Logistics Performance Index (LPI) analyses differences between countries in terms of customs procedures, logistics costs and the quality of the infrastructure for overland and maritime transport. The aim of this article is to analyse the impact that each of these components has on trade in emerging economies using a gravity model. Furthermore, the study also attempts to detect possible advances in logistics in developing countries, which are grouped into five regions (Africa, South America, Far East, Middle East and Eastern Europe) by comparing the first LPI data published in 2007 with the most recent data, released in 2012. The results obtained reveal that improvements in any of the components of the LPI can lead to significant growth in a country’s trade flows. Specifically, LPI components are becoming increasingly important for international trade in many countries in Africa, South America and Eastern Europe.Martí Selva, ML.; Puertas Medina, RM.; García, L. (2014). Importance of the logistics performance index in international trade. Applied Economics. 46(24):2982-2992. doi:10.1080/00036846.2014.916394S298229924624Anderson, J. E., & van Wincoop, E. (2003). Gravity with Gravitas: A Solution to the Border Puzzle. American Economic Review, 93(1), 170-192. doi:10.1257/000282803321455214Bergstrand, J. H. (1985). The Gravity Equation in International Trade: Some Microeconomic Foundations and Empirical Evidence. The Review of Economics and Statistics, 67(3), 474. doi:10.2307/1925976Bergstrand, J. H. (1989). The Generalized Gravity Equation, Monopolistic Competition, and the Factor-Proportions Theory in International Trade. The Review of Economics and Statistics, 71(1), 143. doi:10.2307/1928061De Souza, R., Goh, M., Gupta, S.et al.(2007) An investigation into the measures affecting the integration of ASEAN’s priority sectors: phase 2: the case of logistics.REPSF ProjectNo. 06/001d Regional Economic Policy Support Facility, Association of Southeast Asian Nations, Manila.Heckman, J. J. (1979). Sample Selection Bias as a Specification Error. Econometrica, 47(1), 153. doi:10.2307/1912352Hoekman, B., & Nicita, A. (2010). Assessing the Doha Round: Market access, transactions costs and aid for trade facilitation. The Journal of International Trade & Economic Development, 19(1), 65-79. doi:10.1080/09638190903327476Iwanow, T., & Kirkpatrick, C. (2009). Trade Facilitation and Manufactured Exports: Is Africa Different? World Development, 37(6), 1039-1050. doi:10.1016/j.worlddev.2008.09.014Marti, L., Puertas, R., & García, L. (2012). Relevance of trade facilitation in emerging countries’ exports. The Journal of International Trade & Economic Development, 23(2), 202-222. doi:10.1080/09638199.2012.698639Martínez-Zarzoso, I., & Suárez-Burguet, C. (2000). The determinants of trade performance: influence of R&D on export flows. Applied Economics, 32(15), 1939-1946. doi:10.1080/00036840050155869Mustra, M. A. (2011) Logistic Performance Index, connecting to compete 2010, inUNESCAP Regional Forum and Chief Executives Meeting, The World Bank, Cairo

    Corrections to Nambu-Goto energy levels from the effective string action

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    The effective action on long strings, such as confining strings in pure Yang-Mills theories, is well-approximated by the Nambu-Goto action, but this action cannot be exact. The leading possible corrections to this action (in a long string expansion in the static gauge), allowed by Lorentz invariance, were recently identified, both for closed strings and for open strings. In this paper we compute explicitly in a Hamiltonian formalism the leading corrections to the lowest-lying Nambu-Goto energy levels in both cases, and verify that they are consistent with the previously computed effective string partition functions. For open strings of length R the leading correction is of order 1/R^4, for excited closed strings of length R in D>3 space-time dimensions it is of order 1/R^5, while for the ground state of the closed string in any dimension it is of order 1/R^7. We attempt to match our closed string corrections to lattice results, but the latter are still mostly outside the range of convergence of the 1/R expansion that we use.Comment: 18 pages, 1 figure, JHEP format. v2: added remark on 1/R^7 corrections to ground state energ

    Use of archival versus newly collected tumor samples for assessing PD-L1 expression and overall survival : an updated analysis of KEYNOTE-010 trial

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    Background: In KEYNOTE-010, pembrolizumab versus docetaxel improved overall survival (OS) in patients with programmed death-1 protein (PD)-L1-positive advanced non-small-cell lung cancer (NSCLC). A prespecified exploratory analysis compared outcomes in patients based on PD-L1 expression in archival versus newly collected tumor samples using recently updated survival data. Patients and methods: PD-L1 was assessed centrally by immunohistochemistry (22C3 antibody) in archival or newly collected tumor samples. Patients received pembrolizumab 2 or 10 mg/kg Q3W or docetaxel 75 mg/m2 Q3W for 24 months or until progression/intolerable toxicity/other reason. Response was assessed by RECIST v1.1 every 9 weeks, survival every 2 months. Primary end points were OS and progression-free survival (PFS) in tumor proportion score (TPS) 50% and 1%; pembrolizumab doses were pooled in this analysis. Results: At date cut-off of 24 March 2017, median follow-up was 31 months (range 23-41) representing 18 additional months of follow-up from the primary analysis. Pembrolizumab versus docetaxel continued to improve OS in patients with previously treated, PD-L1-expressing advanced NSCLC; hazard ratio (HR) was 0.66 [95% confidence interval (CI): 0.57, 0.77]. Of 1033 patients analyzed, 455(44%) were enrolled based on archival samples and 578 (56%) on newly collected tumor samples. Approximately 40% of archival samples and 45% of newly collected tumor samples were PD-L1 TPS 50%. For TPS 50%, the OS HRs were 0.64 (95% CI: 0.45, 0.91) and 0.40 (95% CI: 0.28, 0.56) for archival and newly collected samples, respectively. In patients with TPS 1%, OS HRs were 0.74 (95% CI: 0.59, 0.93) and 0.59 (95% CI: 0.48, 0.73) for archival and newly collected samples, respectively. In TPS 50%, PFS HRs were similar across archival [0.63 (95% CI: 0.45, 0.89)] and newly collected samples [0.53 (95% CI: 0.38, 0.72)]. In patients with TPS 1%, PFS HRs were similar across archival [0.82 (95% CI: 0.66, 1.02)] and newly collected samples [0.83 (95% CI: 0.68, 1.02)]. Conclusion: Pembrolizumab continued to improve OS over docetaxel in intention to treat population and in subsets of patients with newly collected and archival samples

    Correlation functions in super Liouville theory

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    We calculate three- and four-point functions in super Liouville theory coupled to super Coulomb gas on world sheets with spherical topology. We first integrate over the zero mode and assume that a parameter takes an integer value. After calculating the amplitudes, we formally continue the parameter to an arbitrary real number. Remarkably the result is completely parallel to the bosonic case, the amplitudes being of the same form as those of the bosonic case.Comment: 11 page

    Polyakov loop correlators from D0-brane interactions in bosonic string theory

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    In this paper we re-derive the effective Nambu-Goto theory result for the Polyakov loop correlator, starting from the free bosonic string and using a covariant quantization. The boundary conditions are those of an open string attached to two D0-branes at spatial distance R, in a target space with compact euclidean time. The one-loop free energy contains topologically distinct sectors corresponding to multiple covers of the cylinder in target space bordered by the Polyakov loops. The sector that winds once reproduces exactly the Nambu-Goto partition function. In our approach, the world-sheet duality between the open and closed channel is most evident and allows for an explicit interpretation of the free energy in terms of tree level exchange of closed strings between boundary states. Our treatment is fully consistent only in d=26; extension to generic d may be justified for large R, and is supported by Montecarlo data. At shorter scales, consistency and Montecarlo data seem to suggest the necessity of taking into account the Liouville mode of Polyakov's formulation.Comment: 17 pages, 4 figures, minor corrections, a few references added, version accepted for publication in JHE

    Quark mass correction to the string potential

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    A consistent method for calculating the interquark potential generated by the relativistic string with massive ends is proposed. In this approach the interquark potential in the model of the Nambu--Goto string with point--like masses at its ends is calculated. At first the calculation is done in the one--loop approximation and then the variational estimation is performed. The quark mass correction results in decreasing the critical distance (deconfinement radius). When quark mass decreases the critical distance also decreases. For obtaining a finite result under summation over eigenfrequencies of the Nambu--Goto string with massive ends a suitable mode--by--mode subtraction is proposed. This renormalization procedure proves to be completely unique. In the framework of the developed approach the one--loop interquark potential in the model of the relativistic string with rigidity is also calculated.Comment: 34 pages, LATE
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