1,010 research outputs found

    T-Duality of Green-Schwarz Superstrings on AdS(d) x S(d) x M(10-2d)

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    We verify the self-duality of Green-Schwarz supercoset sigma models on AdSd×Sd_d \times S^d backgrounds (d=2,3,5) under combined bosonic and fermionic T-dualities without gauge fixing kappa symmetry. We also prove this property for superstrings on AdSd×Sd×Sd_d \times S^d \times S^d (d=2,3) described by supercoset sigma models with the isometries governed by the exceptional Lie supergroups D(2,1;α)D(2,1;\alpha) (d=2) and D(2,1;α)×D(2,1;α)D(2,1;\alpha)\times D(2,1;\alpha) (d=3), which requires an additional T-dualisation along one of the spheres. Then, by taking into account the contribution of non-supercoset fermionic modes (up to the second order), we provide evidence for the T-self-duality of the complete type IIA and IIB Green-Schwarz superstring theory on AdSd×Sd×T102d_d\times S^d \times T^{10-2d} (d=2,3) backgrounds with Ramond-Ramond fluxes. Finally, applying the Buscher-like rules to T-dualising supergravity fields, we prove the T-self-duality of the whole class of the AdSd×Sd×M102d_d\times S^d \times M^{10-2d} superbackgrounds with Ramond-Ramond fluxes in the context of supergravity.Comment: v2: 57 pages, 1 figure, typos fixed and clarifications added, version to appear in JHE

    The nexus of nursing leadership and a culture of safer patient care

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    Aims and objectives: To explore the connection between +6 nursing leadership and enhanced patient safety. Background: Critical reports from the Institute of Medicine in 1999 and Francis QC report of 2013 indicate that healthcare organisations, inclusive of nursing leadership, were remiss or inconsistent in fostering a culture of safety. The factors required to foster organisational safety culture include supportive leadership, effective communication, an orientation programme and ongoing training, appropriate staffing, open communication regarding errors, compliance to policy and procedure, and environmental safety and security. As nurses have the highest patient interaction, and leadership is discernible at all levels of nursing, nurse leaders are the nexus to influencing organisational culture towards safer practices. Design: The position of this article was to explore the need to form a nexus between safety culture and leadership for the provision of safe care. Conclusions: Safety is crucial in health care for patient safety and patient outcomes. A culture of safety has been exposed as a major influence on patient safety practices, heavily influenced by leadership behaviours. The relationship between leadership and safety plays a pivotal role in creating positive safety outcomes for patient care. A safe culture is one nurtured by effective leadership. Relevance to practice: Patient safety is the responsibility of all healthcare workers, from the highest executive to the bedside nurse, thus effective leadership throughout all levels is essential in engaging staff to provide high quality care for the best possible patient outcome

    Scattering in AdS2/CFT1 and the BES phase

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    We study worldsheet scattering for the type IIA superstring in AdS 2 ×S 2 ×T 6. Using the Green-Schwarz action to quartic order in fermions we take the near-BMN limit, where as in the AdS3/CFT2 case there are both massive and massless excitations. For the massive excitations we compute all possible tree-level processes, and show that these agree with a truncated version of the exact AdS 5 × S 5 S-matrix. We also compute several S-matrix elements involving massless excitations. At one loop we find that the dressing phase is the same Hernándes-López phase appearing in AdS5/CFT4. We see the same phase when calculating this by semiclassical means using the PSU(1, 1 2)/U(1)2 coset sigma model, for which we can also study the scattering of fermions. This supports the conjecture that the all-loop dressing phase is again the BES phase, rather than a new phase like that seen in AdS3/CFT2

    Supervisor trainees' and their supervisors' perceptions of attainment of knowledge and skills. An empirical evaluation of a psychotherapy supervisor training programme

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    Objectives. This study aimed to evaluate the success of a two-year, part-time training programme for psychotherapy supervisors. A second aim was to examine factors that might contribute to perceived knowledge and skills attainment during the training course. Design. This is a naturalistic, longitudinal study where several measures are used to examine group process and outcome. Methods. Supervisor trainees’ (n=21) and their facilitators’ (n=6) ratings of learning (knowledge and skills), relations to the supervisor and supervision group, usage of the group, and supervisor style were completed at three time points. Results. The findings suggested that both trainees and their supervisors perceived that the trainees attained a substantial amount of knowledge and skills during the course. In accordance with the literature and expectations, the regression analysis suggested a strong negative association between a strong focus on group processes in the initial and middle phases of the training and perceived knowledge and skills attainment in the final phase of the training. The expected, positive role of relations among trainees in the supervision group in the first half of the training and perceived knowledge and skills attainment in the final part of the training was obtained, whilst the hypothesized significance of the relationship between trainee and supervisor did not receive support. Conclusions The supervisory course seemed to provide a training that allowed trainees to attain knowledge and skills that are necessary for psychotherapy supervisors. The results of this pilot study also emphasize the need of more research on learning in the context of group supervision in psychotherapy

    The low-energy limit of AdS(3)/CFT2 and its TBA

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    We investigate low-energy string excitations in AdS3 × S3 × T4. When the worldsheet is decompactified, the theory has gapless modes whose spectrum at low energies is determined by massless relativistic integrable S matrices of the type introduced by Al. B. Zamolodchikov. The S matrices are non-trivial only for excitations with identical worldsheet chirality, indicating that the low-energy theory is a CFT2. We construct a Thermodynamic Bethe Ansatz (TBA) for these excitations and show how the massless modes’ wrapping effects may be incorporated into the AdS3 spectral problem. Using the TBA and its associated Y-system, we determine the central charge of the low-energy CFT2 to be c = 6 from calculating the vacuum energy for antiperiodic fermions — with the vacuum energy being zero for periodic fermions in agreement with a supersymmetric theory — and find the energies of some excited states

    Classical integrability and quantum aspects of the AdS(3) x S(3) x S(3) x S(1) superstring

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    In this paper we continue the investigation of aspects of integrability of the type IIA AdS(3) x S(3) x S(3) x S(1) and AdS(3) x S(3) x T(4) superstrings. By constructing a one parameter family of flat connections we prove that the Green-Schwarz string is classically integrable, at least to quadratic order in fermions, without fixing the kappa-symmetry. We then compare the quantum dispersion relation, fixed by integrability up to an unknown interpolating function h(lambda), to explicit one-loop calculations on the string worldsheet. For AdS(3) x S(3) x S(3) x S(1) the spectrum contains heavy, as well as light and massless modes, and we find that the one-loop contribution differs depending on how we treat these modes showing that similar regularization ambiguities as appeared in AdS(4)/CFT(3) occur also here.Comment: 29 pages; v2: updated references and acknowledgmen

    On the worldsheet theory of the type IIA AdS(4) x CP(3) superstring

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    We perform a detailed study of the type IIA superstring in AdS(4) x CP(3). After introducing suitable bosonic light-cone and fermionic kappa worldsheet gauges we derive the pure boson and fermion SU(2|2) x U(1) covariant light-cone Hamiltonian up to quartic order in fields. As a first application of our derivation we calculate energy shifts for string configurations in a closed fermionic subsector and successfully match these with a set of light-cone Bethe equations. We then turn to investigate the mismatch between the degrees of freedom of scattering states and oscillatory string modes. Since only light string modes appear as fundamental Bethe roots in the scattering theory, the physical role of the remaining 4F+4B4_F+4_B massive oscillators is rather unclear. By continuing a line of research initiated by Zarembo, we shed light on this question by calculating quantum corrections for the propagators of the bosonic massive fields. We show that, once loop corrections are incorporated, the massive coordinates dissolve in a continuum state of two light particles.Comment: 40 pages, 2 figures. v3: Minor clarifications made and reference list updated. Published version

    Factorized Tree-level Scattering in AdS_4 x CP^3

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    AdS_4/CFT_3 duality relating IIA string theory on AdS_4 x CP^3 to N=6 superconformal Chern-Simons theory provides an arena for studying aspects of integrability in a new potentially exactly solvable system. In this paper we explore the tree-level worldsheet scattering for strings on AdS_4 x CP^3. We compute all bosonic four-, five- and six-point amplitudes in the gauge-fixed action and demonstrate the absence of particle production.Comment: 23 pages, v2. references adde

    Weakly coupled N=4 Super Yang-Mills and N=6 Chern-Simons theories from u(2|2) Yangian symmetry

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    In this paper we derive the universal R-matrix for the Yangian Y(u(2|2)), which is an abstract algebraic object leading to rational solutions of the Yang-Baxter equation on representations. We find that on the fundamental representation the universal R-matrix reduces to the standard rational R-matrix R = R_0(1 + P/u), where the scalar prefactor is surprisingly simple compared to prefactors one finds e.g. for sl(n) R-matrices. This leads precisely to the S-matrix giving the Bethe Ansatz of one-loop N = 4 Super Yang-Mills theory and two-loop N = 6 Chern-Simons theory.Comment: 16 page
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