168 research outputs found

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

    Full text link
    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

    The effective string spectrum in the orthogonal gauge

    Full text link
    The low-energy effective action on long string-like objects in quantum field theory, such as confining strings, includes the Nambu-Goto action and then higher-derivative corrections. This action is diffeomorphism-invariant, and can be analyzed in various gauges. Polchinski and Strominger suggested a specific way to analyze this effective action in the orthogonal gauge, in which the induced metric on the worldsheet is conformally equivalent to a flat metric. Their suggestion leads to a specific term at the next order beyond the Nambu-Goto action. We compute the leading correction to the Nambu-Goto spectrum using the action that includes this term, and we show that it agrees with the leading correction previously computed in the static gauge. This gives a consistency check for the framework of Polchinski and Strominger, and helps to understand its relation to the theory in the static gauge.Comment: 21 page

    Efficacy and safety of moxifloxacin in hospitalized patients with secondary peritonitis : pooled analysis of four randomized phase III trials

    Get PDF
    Background: Secondary peritonitis is an advanced form of complicated intra-abdominal infection (cIAI) requiring hospitalization, surgical source control, and empiric antibiotic therapy against causative aerobic and anaerobic bacteria. Methods: This pooled analysis of four prospective, active-controlled randomized clinical trials compared the efficacy and safety of moxifloxacin with that of comparator antibiotics in patients with confirmed secondary peritonitis. The primary efficacy endpoint was clinical success rate at test-of-cure (TOC) between day 10 and 45 post-therapy in the per-protocol (PP) population. Safety and clinical efficacy were assessed also in the intent-to-treat population (ITT). Bacteriological success was assessed at TOC in the microbiologically-valid population as a secondary efficacy endpoint. Results: Overall clinical success rates at TOC were 85.3% (431 of 505 patients) in the moxifloxacin and 88.4% (459 of 519 patients) in the comparator treatment groups (PP population, point estimate for the difference in success rates: -3.0%; 95% CI -7.06%, 1.05%), respectively. Similar clinical success rates between moxifloxacin and comparators were observed by anatomical site of infection, and ranged from 80.6% to 100% for moxifloxacin and from 71.4% to 96.6% for comparators, respectively. Bacteriologic success rates were similar with moxifloxacin (82.4%) and comparators (86.8%), respectively. The proportion of patients experiencing any treatment-emergent adverse events was slightly higher with moxifloxacin (67.3%) versus comparators (59.8%). Rates of drug-related adverse events (20.9% versus 20.0%) and deaths (4.3% versus 3.4%) were similar in moxifloxacin and comparator groups; none of the deaths were drug-related. Conclusions: The data suggests that once-daily IV (or IV/PO) moxifloxacin has a comparable efficacy and safety profile to antibiotic regimens approved previously in the subgroup of patients with secondary peritonitis of mild-to-moderate severity

    Correlation functions in super Liouville theory

    Full text link
    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

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

    No full text
    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

    Constructing a logistics space: perspectives form the Gulf Cooperation Council

    Get PDF
    Development plans across the Gulf Cooperation Council emphasise logistical infrastructure as a driver of economic diversification. Investments in maritime ports, roads, rail, airports and logistics cities are transforming the economic geography of the region. This study aims to make visible this neglected aspect of the physical transformation of the Gulf Cooperation Council with a focus on the understudied maritime container ports in Oman and Qatar. Shifting the analysis to emergent maritime logistical infrastructure at a regional level gives insight into the uneven developments within the Gulf Cooperation Council’s integration project. Three key features emerge: (a) a large degree of duplication in maritime port infrastructure across Gulf Cooperation Council states; (b) a regional hierarchy among Gulf Cooperation Council states that are resource rich and those dependent on public–private partnerships and (c) increasing competition among internationally dominant port operators looking to gain access to the Gulf Cooperation Council maritime port market. These features both reflect and reinforce competitive tensions within the regional integration project

    Quark mass correction to the string potential

    Get PDF
    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

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

    Get PDF
    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

    Can holography reproduce the QCD Wilson line?

    Full text link
    Recently a remarkable agreement was found between lattice simulations of long Wilson lines and behavior of the Nambu Goto string in flat space-time. However, the latter fails to fit the short distance behavior since it admits a tachyonic mode for a string shorter than a critical length. In this paper we examine the question of whether a classical holographic Wilson line can reproduce the lattice results for Wilson lines of any length. We determine the condition on the the gravitational background to admit a Coulombic potential at short distances. We analyze the system using three different renormalization schemes. We perform an explicit best fit comparison of the lattice results with the holographic models based on near extremal D3 and D4 branes, non-critical near extremal AdS6 model and the Klebanov Strassler model. We find that all the holographic models examined admit after renormalization a constant term in the potential. We argue that the curves of the lattice simulation also have such a constant term and we discuss its physical interpretation
    corecore