The λΛ\lambda\Lambda interaction and the reaction Ξ−+d→n+Λ+Λ\Xi^- + d \to n + \Lambda + \Lambda

The $\Lambda\Lambda$ interaction resulting from the SU(3) rotation of the S-wave component of the Nijmegen OBE potential $D$ is used to calculate the binding energy of $^{ 6}_{\Lambda\Lambda}$He as a $\Lambda\Lambda\alpha$ three-body system, and the neutron differential energy spectrum for the reaction $\Xi^- + d \to n + \Lambda + \Lambda$.Comment: 5 pages and 9 eps file

Learning to breathe with Tai Chi online - qualitative data from a randomized controlled feasibility study of patients with cystic fibrosis

Introduction Tai Chi (TC), a gentle exercise, incorporates meditative movement and respiratory control. The high risk of cross infection for people with cystic fibrosis (CF) requires close management in healthcare settings, limiting group activities such as TC. A mixed-methods randomized controlled feasibility study compared teaching TC over the internet with in-person, face to face TC tuition provided to CF patients. This article explores qualitative data from patients and TC instructors on their attitudes, acceptability and engagement with the two modes of TC delivery. Methods Qualitative data from CF patients (>6 years) were collected using Skype interviews/focus groups and written feedback. TC instructors provided weekly written feedback, and took part in interviews/ focus groups at the end of the study. Patient and instructor interviews explored their experiences and engagement with TC online delivery and ability to practice. Results Irrespective of the type of TC delivery, all CF participants interviewed (n = 28) practiced between lessons and most wanted to continue TC. Teenagers were more likely to miss TC appointments. Internet delivery was well received by both patients and TC instructors. Two patients reported difficulties with screen size/camera and one with internet connectivity. Conclusion Both face-to-face and internet delivery of TC lessons were equally well received and perceived as beneficial. In the current COVID-19 pandemic, CF patients self-isolating could find this intervention provides important support, therefore the programme was made available on YouTube in April 2020 and linked to the websites of the CF charities funding the research

Children and Adults Tai Chi Study: a randomised feasibility study comparing internet delivered with face to face Tai Chi lessons in cystic fibrosis

Virtual health care is fast entering medical practice. Research into the feasibility of using it to teach treatment regimens such as exercise has not been explored. Maintaining an exercise regime can be difficult in cystic fibrosis: group classes risk potential infection yet motivation is hard to maintain when alone. Tai Chi is low impact and involves gentle, demanding movements. This study aimed to assess the feasibility, safety and acceptability of learning Tai Chi via an internet based approach and compared patient reported outcomes. Methods: Children and adults with cystic fibrosis were recruited to a randomised, comparative effectiveness trial. Participants learnt eight Tai Chi movements, teaching was delivered in eight lessons over 3 months: either internet delivered or face to face. Assessments were at three monthly intervals over nine-months. Outcomes included health status, quality of life, sleep, mindfulness and instructor-led questions. Results: Forty adults and children completed the eight sets of Tai Chi lessons. The median age was 22.8 years (range 6.1 to 51.5). Twenty-seven were female. Twenty-six adults (>16 years), six teenagers and eight <12 years. The groups were well matched. Feasibility and safety were demonstrated. Participants showed significant improvements in self-reported sleep, cough (both day and night time), stomach ache and breathing. No differences in lung function, health status, QoL, sleep or mindfulness was shown before or after completing the lessons. Conclusions: Tai Chi was safe well tolerated, it was feasible to deliver individual lessons via the internet reducing concerns regarding cross infection and appeared to improve self-reported symptoms. Copyright ©ERS 201

Classical aspects of Hawking radiation verified in analogue gravity experiment

There is an analogy between the propagation of fields on a curved spacetime and shallow water waves in an open channel flow. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include wave horizons. Long (shallow water) waves propagating upstream towards this region are blocked and converted into short (deep water) waves. This is the analogue of the stimulated Hawking emission by a white hole (the time inverse of a black hole). The measurements of amplitudes of the converted waves demonstrate that they appear in pairs and are classically correlated; the spectra of the conversion process is described by a Boltzmann-distribution; and the Boltzmann-distribution is determined by the determined by the change in flow across the white hole horizon.Comment: 17 pages, 10 figures; draft of a chapter submitted to the proceedings of the IX'th SIGRAV graduate school: Analogue Gravity, Lake Como, Italy, May 201

Hawking radiation of nonsingular black holes in two dimensions

In this letter we study the process of Hawking radiation of a black hole assuming the existence of a limiting physical curvature scale. The particular model is constructed using the Limiting Curvature Hypothesis (LCH) and in the context of two-dimensional dilaton gravity. The black hole solution exhibits properties of the standard Schwarzschild solution at large values of the radial coordinate. However, near the center, the black hole is nonsingular and the metric becomes that of de Sitter spacetime. The Hawking temperature is calculated using the method of complex paths. We find that such black holes radiate eternally and never completely evaporate. The final state is an eternally radiating relic, near the fundamental scale, which should make a viable dark matter candidate. We briefly comment on the black hole information loss problem and the production of such black holes in collider experiments.Comment: 8 pages, 4 figures; minor revisions; references added; version to appear in JHE

Faddeev calculations for the A=5,6 Lambda-Lambda hypernuclei

Faddev calculations are reported for Lambda-Lambda-5H, Lambda-Lambda-5He and Lambda-Lambda-6He in terms of two Lambda hyperons plus the respective nuclear clusters, using Lambda-Lambda central potentials considered in past non-Faddeev calculations of Lambda-Lambda-6He. The convergence with respect to the partial-wave expansion is studied, and comparison is made with some of these Lambda-Lambda hypernuclear calculations. The Lambda-Lambda Xi-N mixing effect is briefly discussed.Comment: submitted for publicatio

Dynamics of a large extra dimension inspired hybrid inflation model

In low scale quantum gravity scenarios the fundamental scale of nature can be as low as TeV, in order to address the naturalness of the electroweak scale. A number of difficulties arise in constructing specific models; stabilisation of the radius of the extra dimensions, avoidance of overproduction of Kaluza Klein modes, achieving successful baryogenesis and production of a close to scale-invariant spectrum of density perturbations with the correct amplitude. We examine in detail the dynamics, including radion stabilisation, of a hybrid inflation model that has been proposed in order to address these difficulties, where the inflaton is a gauge singlet residing in the bulk. We find that for a low fundamental scale the phase transition, which in standard four dimensional hybrid models usually ends inflation, is slow and there is second phase of inflation lasting for a large number of e-foldings. The density perturbations on cosmologically interesting scales exit the Hubble radius during this second phase of inflation, and we find that their amplitude is far smaller than is required. We find that the duration of the second phase of inflation can be short, so that cosmologically interesting scales exit the Hubble radius prior to the phase transition, and the density perturbations have the correct amplitude, only if the fundamental scale takes an intermediate value. Finally we comment briefly on the implications of an intermediate fundamental scale for the production of primordial black holes and baryogenesis.Comment: 9 pages, 2 figures version to appear in Phys. Rev. D, additional references and minor changes to discussio

Carbon Nanotubes as Nanoelectromechanical Systems

We theoretically study the interplay between electrical and mechanical properties of suspended, doubly clamped carbon nanotubes in which charging effects dominate. In this geometry, the capacitance between the nanotube and the gate(s) depends on the distance between them. This dependence modifies the usual Coulomb models and we show that it needs to be incorporated to capture the physics of the problem correctly. We find that the tube position changes in discrete steps every time an electron tunnels onto it. Edges of Coulomb diamonds acquire a (small) curvature. We also show that bistability in the tube position occurs and that tunneling of an electron onto the tube drastically modifies the quantized eigenmodes of the tube. Experimental verification of these predictions is possible in suspended tubes of sub-micron length.Comment: 8 pages, 5 eps figures included. Major changes; new material adde