4,223 research outputs found

    S and U-duality Constraints on IIB S-matrices

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    S and U-duality dictate that graviton scattering amplitudes in IIB superstring theory be automorphic functions on the appropriate fundamental domain which describe the inequivalent vacua of (compactified) theories. A constrained functional form of graviton scattering is proposed using Eisenstein series and their generalizations compatible with: a) two-loop supergravity, b) genus one superstring theory, c) the perturbative coupling dependence of the superstring, and d) with the unitarity structure of the massless modes. The form has a perturbative truncation in the genus expansion at a given order in the derivative expansion. Comparisons between graviton scattering S-matrices and effective actions for the first quantized superstring are made at the quantum level. Possible extended finiteness properties of maximally extended quantum supergravity theories in different dimensions is implied by the perturbative truncation of the functional form of graviton scattering in IIB superstring theory.Comment: 36 pages, 5 figures, LaTeX, (minor) eq. corr., to appear in NP

    The Intermediate Coupling Regime in the AdS/CFT Correspondence

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    The correspondence between the 't Hooft limit of N=4 super Yang-Mills theory and tree-level IIB superstring theory on AdS(5)xS(5) in a Ramond-Ramond background at values of lambda=g^2 N ranging from infinity to zero is examined in the context of unitarity. A squaring relation for the imaginary part of the holographic scattering of identical string fields in the two-particle channels is found, and a mismatch between weak and strong 't Hooft coupling is pointed out within the correspondence. Several interpretations and implications are proposed.Comment: 10 pages, LaTeX, reference adde

    Superconformal hypermultiplets in superspace

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    We use the manifestly N=2 supersymmetric, off-shell, harmonic (or twistor) superspace approach to solve the constraints implied by four-dimensional N=2 superconformal symmetry on the N=2 non-linear sigma-model target space, known as the special hyper-K"ahler geometry. Our general solution is formulated in terms of a homogeneous (of degree two) function of unconstrained (analytic) Fayet-Sohnius hypermultiplet superfields. We also derive the improved (N=2 superconformal) actions for the off-shell (constrained) N=2 projective hypermultiplets, and relate them (via non-conformal deformations) to the asymptotically locally-flat (ALF) A_k and D_k series of the gravitational instantons. The same metrics describe Kaluza-Klein monopoles in M-theory, while they also arise in the quantum moduli spaces of N=4 supersymmetric gauge field theories with SU(2) gauge group and matter hypermultiplets in three spacetime dimensions. We comment on rotational isometries versus translational isometries in the context of N=2 NLSM in terms of projective hypermultiplets.Comment: 28 pages, LaTeX; minor improvements, to appear in Nucl. Phys.

    Inhaled liposomal ciprofloxacin in patients with non-cystic fibrosis bronchiectasis and chronic lung infection with Pseudomonas aeruginosa (ORBIT-3 and ORBIT-4):two phase 3, randomised controlled trials

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    In patients with non-cystic fibrosis bronchiectasis, lung infection with Pseudomonas aeruginosa is associated with frequent pulmonary exacerbations and admission to hospital for treatment, reduced quality of life, and increased mortality. Although inhaled antibiotics are conditionally recommended for long-term management of non-cystic fibrosis bronchiectasis with frequent exacerbations, there is no approved therapy. We investigated the safety and efficacy of inhaled liposomal ciprofloxacin (ARD-3150) in two phase 3 trials. ORBIT-3 and ORBIT-4 were international, randomised, double-blind, placebo-controlled, phase 3 trials run concurrently in similar geographical regions. Eligible patients had non-cystic fibrosis bronchiectasis, had had at least two pulmonary exacerbations treated with antibiotics in the previous 12 months, and had a history of chronic P aeruginosa lung infection. Patients were randomly assigned (2:1) to receive either ARD-3150 or placebo. ARD-3150 (3 mL liposome encapsulated ciprofloxacin 135 mg and 3 mL free ciprofloxacin 54 mg) or 6 mL placebo (3 mL dilute empty liposomes mixed with 3 mL of saline) was self-administered once daily for six 56-day treatment cycles, for 48 weeks. The primary endpoint was time to first pulmonary exacerbation from the date of randomisation to week 48. We did primary and secondary efficacy, safety, and microbiology analyses on the full analysis population, which comprised all randomised patients who received at least one dose of study drug. ORBIT-3 and ORBIT-4 are registered with ClinicalTrials.gov, numbers NCT01515007 and NCT02104245, respectively. Between March 31, 2014, and Aug 19, 2015, we screened 514 patients in ORBIT-3 and 533 patients in ORBIT-4. The full analysis populations consisted of 278 patients in ORBIT-3 (183 patients received at least one dose of ARD-3150 and 95 received placebo) and 304 patients in ORBIT-4 (206 patients received at least one dose of ARD-3150 and 98 received placebo). In ORBIT-4, the median time to first pulmonary exacerbation was 230 days in the ARD-3150 group compared with 158 days in the placebo group, a statistically significant difference of 72 days (hazard ratio [HR] 0·72 [95% CI 0·53-0·97], p=0·032). In ORBIT-3, the median time to first pulmonary exacerbation was 214 days in the ARD-3150 group and 136 days in the placebo group, a non-statistically significant difference of 78 days (HR 0·99 [95% CI 0·71-1·38], p=0·97). In a pooled analysis of data from both ORBIT-3 and ORBIT-4, the median time to first pulmonary exacerbation was 222 days in the ARD-3150 group and 157 days in the placebo group, a non-statistically significant difference of 65 days (0·82 [0·65-1·02], p=0·074). The numbers of adverse events and serious adverse events were similar in both groups in ORBIT-3 and ORBIT-4. In patients with non-cystic fibrosis bronchiectasis and chronic P aeruginosa lung infection requiring antibiotic therapy in the preceding year, ARD-3150 led to a significantly longer median time to first pulmonary exacerbation compared with placebo in ORBIT-4, but not in ORBIT-3 or the pooled analysis. Inconsistency between the trials suggests further research is needed into the heterogeneity of non-cystic fibrosis bronchiectasis and optimal outcome measures for inhaled antibiotics. Aradigm Corporation

    The appeal of the Functional Fitness MOT to older adults and health professionals in an outpatient setting: a mixed-method feasibility study

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    Purpose: To understand the views and perceptions regarding the Functional Fitness MOT (FFMOT), a battery of functional tests followed by a brief motivational interview, of both the older people undergoing it and the health professionals delivering it. Patients and methods: Physically inactive older adults (n=29) underwent the FFMOT and subsequently attended focus groups to share their perceptions of it and to discuss the barriers, motivators, health behavior change, and scope to improve physical activity (PA) levels. PA levels were recorded at baseline and again at 12 weeks together with a post-intervention questionnaire concerning behavior change. Participating physiotherapists and technical instructors were interviewed. Results: Most participants felt they had learned about their abilities and comparisons with their peers, had a change in perception about the importance of good balance and strength, and felt the FFMOT helped raise their awareness of local and self-directed physical activity opportunities. Most felt their awareness of the need for PA had not changed, but 25% of participants started a new organized PA opportunity. The health professionals perceived the FFMOT as being easy to administer, educating, and motivating for participants to increase their PA. Space, time, finances, and insecurity about having the necessary skills to conduct the FFMOTs were seen as barriers in implementing the FFMOT in daily practice. Conclusion: Over half of those offered the FFMOT accepted it, suggesting it is appealing. However, most participants felt they were already active enough and that their awareness of the need for PA had not changed. There were positive perceptions of the FFMOT from both professionals and older people, but both felt the FFMOT could be held in a community venue. The overall findings suggest that the FFMOT is feasible in the clinical setting, but its effectiveness has yet to be determined

    On the nonlinear KK reductions on spheres of supergravity theories

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    We address some issues related to the construction of general Kaluza-Klein (KK) ans\"atze for the compactification of a supergravity (sugra) theory on a sphere SmS_m. We first reproduce various ans\"atze for compactification to 7d from the ansatz for the full nonlinear KK reduction of 11d sugra on AdS7×S4AdS_7\times S_4. As a side result, we obtain a lagrangian formulation of 7d N=2{\cal N}=2 gauged sugra, which so far had only a on-shell formulation, through field equations and constraints. The AdS7×S4AdS_7\times S_4 ansatz generalizes therefore all previous sphere compactifications to 7d. Then we consider the case when the scalars in the lower dimensional theory are in a coset Sl(m+1)/SO(m+1)Sl(m+1)/SO(m+1), and we keep the maximal gauge group SO(m+1)SO(m+1). The 11-dimensional sugra truncated on S4S_4 fits precisely the case under consideration, and serves as a model for our construction. We find that the metric ansatz has a universal expression, with the internal space deformed by the scalar fluctuations to a conformally rescaled ellipsoid. We also find the ansatz for the dependence of the antisymmetric tensor on the scalars. We comment on the fermionic ansatz, which will contain a matrix UU interpolating between the spinorial SO(m+1)SO(m+1) indices of the spherical harmonics and the RR-symmetry indices of the fermionic fields in the lower dimensional sugra theory. We derive general conditions which the matrix UU has to satisfy and we give a formula for the vielbein in terms of UU. As an application of our methods we obtain the full ansatz for the metric and vielbein for 10d sugra on AdS5×S5AdS_5\times S_5 (with no restriction on any fields).Comment: 26 pages, latex, no figures, references added, typos correcte

    Effects of D-instantons in string amplitudes

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    We investigate the different energy regimes in the conjectured SL(2,Z) invariant four graviton scattering amplitude that incorporates D-instanton contributions in 10d type IIB superstring theory. We show that the infinite product over SL(2,Z) rotations is convergent in the whole complex plane s,t. For high energies s>> 1, fixed scattering angle, and very weak coupling g<< 1/s, the four-graviton amplitude exhibits the usual exponential suppression. As the energy approaches 1/g, the suppression gradually diminishes until there appears a strong amplification near a new pole coming from the exchange of a (p,q) string. At energies s<< 1/\sqrt{g}, the pure D instanton contribution to the scattering amplitude is found to produce a factor A4Dinstexp(cg3/2e2πgs3)A_4^{Dinst}\cong \exp (c g^{3/2}e^{-{2\pi\over g}} s^3). At energies 1/g<<s<<1/g1/\sqrt{g} << s<< 1/g , the D-instanton factor becomes A4Dinstexp(2e2πgs+πgss2)A_4^{Dinst}\cong \exp (2 e^{-{2\pi\over g_s}+\pi g_s s^2}). At higher energies s>> 1/g the D-instanton contribution becomes very important, and one finds an oscillatory behavior which alternates suppression and amplification. This suggests that non-perturbative effects can lead to a high-energy behavior which is significantly different from the perturbative string behavior.Comment: 11 pages, 3 figure

    The European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC):experiences from a successful ERS Clinical Research Collaboration

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    In contrast to airway diseases like chronic obstructive pulmonary disease or asthma, and rare diseases such as cystic fibrosis, there has been little research and few clinical trials in bronchiectasis. Guidelines are primarily based on expert opinion and treatment is challenging because of the heterogeneous nature of the disease. In an effort to address decades of underinvestment in bronchiectasis research, education and clinical care, the European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC) was established in 2012 as a collaborative pan-European network to bring together bronchiectasis researchers. The European Respiratory Society officially funded EMBARC in 2013 as a Clinical Research Collaboration, providing support and infrastructure to allow the project to grow. EMBARC has now established an international bronchiectasis registry that is active in more than 30 countries both within and outside Europe. Beyond the registry, the network participates in designing and facilitating clinical trials, has set international research priorities, promotes education and has participated in producing the first international bronchiectasis guidelines. This manuscript article the development, structure and achievements of EMBARC from 2012 to 2017. EDUCATIONAL AIMS: To understand the role of Clinical Research Collaborations as the major way in which the European Respiratory Society can stimulate clinical research in different disease areasTo understand some of the key features of successful disease registriesTo review key epidemiological, clinical and translational studies of bronchiectasis contributed by the European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC) project in the past 5 yearsTo understand the key research priorities identified by EMBARC for the next 5 years

    Bronchiectasis:an emerging global epidemic

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    Abstract Bronchiectasis has an increasing profile within respiratory medicine. This chronic and irreversible airways disease is common but suffers from a lack of evidenced based therapy for patients and, a lack of understanding of its inherent heterogeneity. Research focused on bronchiectasis must therefore be prioritized if we are to adequately address this evolving clinical problem. This special issue on bronchiectasis focuses on its clinical, microbiological and therapeutic aspects. By bringing together a unique collection of original research and review articles, we hope this issue will showcase international research efforts, encourage future research collaborations and stimulate debate. In doing so, we hope to bring greater attention to the urgent need for sustained investment into focused, dedicated and collaborative research platforms in bronchiectasis, an emerging “global epidemic”
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