String Propagation through a Big Crunch/Big Bang Transition

We consider the propagation of classical and quantum strings on cosmological space-times which interpolate from a collapsing phase to an expanding phase. We begin by considering the classical propagation of strings on space-times with isotropic and anisotropic cosmological singularities. We find that cosmological singularities fall into two classes, in the first class the string evolution is well behaved all the way up to the singularity, whilst in the second class it becomes ill-defined. Then assuming the singularities are regulated by string scale corrections, we consider the implications of the propagation through a `bounce'. It is known that as we evolve through a bounce, quantum strings will become excited giving rise to `particle transmutation'. We reconsider this effect, giving qualitative arguments for the amount of excitation for each class. We find that strings whose physical wavelength at the bounce is less that $\sqrt{\alpha'}$ inevitably emerge in highly excited states, and that in this regime there is an interesting correspondence between strings on anisotropic cosmological space-times and plane waves. We argue that long wavelength modes, such as those describing cosmological perturbations, will also emerge in mildly excited string scale mass states. Finally we discuss the relevance of this to the propagation of cosmological perturbations in models such as the ekpyrotic/cyclic universe.Comment: 15 page

Digital literacy education for UK undergraduate pharmacy students: A mixed-methods study

\ua9 2024 The Author(s). Objectives: Digital literacy is increasingly crucial in pharmacy practice, and relevant education and training are required to prepare the future workforce. This study aims to explore the current and planned inclusion of digital literacy education in the undergraduate curricula of UK pharmacy schools. Methods: A mixed-methods approach was conducted with two phases. The first involved a content analysis of published curricula from all 30 UK pharmacy schools. The second phase included a survey based on the Health Education England Digital Capabilities Framework, distributed to academic staff across all pharmacy schools. Key findings: Data from 14 pharmacy schools\u27 curricula were included in the analysis, with 10 reporting digital literacy education. Key themes identified from the analysed documents included understanding of health informatics, applied informatics, information technology skills, and the emerging digital health technology. Nineteen respondents from 16 schools participated in the survey; digital literacy inclusion was reported by 18 participants. There was variable alignment of digital literacy competencies with the Health Education England framework. Digital literacy was mainly integrated into existing teaching sessions, predominantly through self-learning (n = 12). Electronic Health Records and remote counselling were the main focus areas within the curricula. Challenges in implementing digital literacy include a lack of expertise (n = 13), and time constraints (n = 10). Conclusions: The trend towards embedding digital literacy in UK pharmacy curricula is clear, but disparities suggest the need for a more unified strategy. Recommendations include establishing a specific digital literacy framework aligned with professional needs, improving accessibility and transparency in curricula documents, and investing in faculty development

Scaling Solutions to 6D Gauged Chiral Supergravity

We construct explicitly time-dependent exact solutions to the field equations of 6D gauged chiral supergravity, compactified to 4D in the presence of up to two 3-branes situated within the extra dimensions. The solutions we find are scaling solutions, and are plausibly attractors which represent the late-time evolution of a broad class of initial conditions. By matching their near-brane boundary conditions to physical brane properties we argue that these solutions (together with the known maximally-symmetric solutions and a new class of non-Lorentz-invariant static solutions, which we also present here) describe the bulk geometry between a pair of 3-branes with non-trivial on-brane equations of state.Comment: Contribution to the New Journal of Physics focus issue on Dark Energy; 28 page

The cosmic gravitational wave background in a cyclic universe

Inflation predicts a primordial gravitational wave spectrum that is slightly ``red,'' i.e., nearly scale-invariant with slowly increasing power at longer wavelengths. In this paper, we compute both the amplitude and spectral form of the primordial tensor spectrum predicted by cyclic/ekpyrotic models. The spectrum is blue and exponentially suppressed compared to inflation on long wavelengths. The strongest observational constraint emerges from the requirement that the energy density in gravitational waves should not exceed around 10 per cent of the energy density at the time of nucleosynthesis.Comment: 4 pages, 3 figuer

Flux compactifications and supersymmetry breaking in 6D gauged supergravity

We review on a recent construction of the on-shell supersymmetric brane action for the codimension-two branes with nonzero tension in the flux compactification of a 6D chiral gauged supergravity. On dimesionally reducing on 4D gauged supergravity for a new supersymmetric unwarped background with conical branes, we consider the modulus stabilization for determining the soft masses of the scalars localized on the branes and show that the bulk U(1)_R provides a new mechanism for mediating the SUSY breaking.Comment: 12 pages, no figures, Invited review for Modern Physics Letters A, Published versio

Supersymmetric codimension-two branes in six-dimensional gauged supergravity

We consider the six-dimensional Salam-Sezgin supergravity in the presence of codimension-2 branes. In the case that the branes carry only tension, we provide a way to supersymmetrise them by adding appropriate localised Fayet-Iliopoulos terms and localised corrections to the Chern-Simons term and modifying accordingly the fermionic supersymmetry transformations. The resulting brane action has N=1 supersymmetry (SUSY). We find the axisymmetric vacua of the system and show that one has unwarped background solutions with "football"-shaped extra dimensions which always respect N=1 SUSY for any value of the equal brane tensions, in contrast with the non-supersymmetric brane action background. Finally, we generically find multiple zero modes of the gravitino in this background and discuss how one could obtain a single chiral zero mode present in the low energy spectrum.Comment: 21 pages, no figures, A sign error in the gauge potential at the lower brane corrected and its consequent effect discusse