A geometrical instability for ultra-light fields during inflation?

Westudythebehaviourofisocurvatureperturbationsinnon-linearsigmamodels which naturally emerge in supergravity and string inflationary scenarios. We focus on the case of negatively curved field manifolds which can potentially lead to a geometrical destabilisation of isocurvature modes. We find however that heavy fields are stable when their effective mass is computed on the attractor background solution. On the other hand, we show that ultra-light fields can potentially suffer from a geometrical instability when the background trajectory is a geodesic in field space. In this case a full understanding of the system is likely to require the use of non-perturbative methods.Comment: Matches published version, 5 pages, 2 figure

Supporting children and young people to assume responsibility from their parents for the self-management of their long-term condition: An integrative review

© 2019 John Wiley & Sons Ltd Background: Children and young people with long-term conditions (LTCs) are usually dependent on, or share management with, their families and are expected to develop self-management skills as they mature. However, during adolescence, young people can find it challenging to follow prescribed treatment regimens resulting in poor clinical outcomes. Though reviews have looked at children's and parents' experiences of self-management, none have explicitly examined the parent-to-child transfer of self-management responsibility. Methods: An integrative review was conducted with the aim of exploring the parent-to-child transfer of LTC self-management responsibility, through addressing two questions: (a) How do children assume responsibility from their parents for self-management of their LTC? (b) What influences the parent-to-child transfer of this responsibility? Eight databases were searched for papers published from 1995 to 2017. Methodological quality was assessed; included papers were synthesized to identify themes. Results: Twenty-nine papers were identified. Most papers used qualitative designs and focused on children with diabetes. Participants were predominantly children and/or parents; only two studies included health professionals. Assuming self-management responsibility was viewed as part of normal development but was rarely explored within the context of the child gaining independence in other areas of their life. Children and parents adopted strategies to help the transfer, but there was limited evidence around health professionals' roles and ambivalence around what was helpful. There was a lack of clarity over whether children and parents were aiming for shared management, or self-management, and whether this was a realistic or desired goal for families. Multiple factors such as the child, family, social networks, health professional, and LTC influenced how a child assumed responsibility. Conclusions: Evidence suggests that the parent-to-child transfer of self-management responsibility is a complex, individualized process. Further research across childhood LTCs is needed to explore children's, parents', and professionals' views on this process and what support families require as responsibilities change

Acute- and late-phase matrix metalloproteinase (MMP)-9 activity is comparable in female and male rats after peripheral nerve injury.

BACKGROUND:In the peripheral nerve, pro-inflammatory matrix metalloproteinase (MMP)-9 performs essential functions in the acute response to injury. Whether MMP-9 activity contributes to late-phase injury or whether MMP-9 expression or activity after nerve injury is sexually dimorphic remains unknown. METHODS:Patterns of MMP-9 expression, activity and excretion were assessed in a model of painful peripheral neuropathy, sciatic nerve chronic constriction injury (CCI), in female and male rats. Real-time Taqman RT-PCR for MMP-9 and its endogenous inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1) of nerve samples over a 2-month time course of CCI was followed by gelatin zymography of crude nerve extracts and purified MMP-9 from the extracts using gelatin Sepharose-beads. MMP excretion was determined using protease activity assay of urine in female and male rats with CCI. RESULTS:The initial upsurge in nerve MMP-9 expression at day 1 post-CCI was superseded more than 100-fold at day 28 post-CCI. The high level of MMP-9 expression in late-phase nerve injury was accompanied by the reduction in TIMP-1 level. The absence of MMP-9 in the normal nerve and the presence of multiple MMP-9 species (the proenzyme, mature enzyme, homodimers, and heterodimers) was observed at day 1 and day 28 post-CCI. The MMP-9 proenzyme and mature enzyme species dominated in the early- and late-phase nerve injury, consistent with the high and low level of TIMP-1 expression, respectively. The elevated nerve MMP-9 levels corresponded to the elevated urinary MMP excretion post-CCI. All of these findings were comparable in female and male rodents. CONCLUSION:The present study offers the first evidence for the excessive, uninhibited proteolytic MMP-9 activity during late-phase painful peripheral neuropathy and suggests that the pattern of MMP-9 expression, activity, and excretion after peripheral nerve injury is universal in both sexes

Entanglement transfer from electron spins to photons in spin light-emitting diodes containing quantum dots

We show that electron recombination using positively charged excitons in single quantum dots provides an efficient method to transfer entanglement from electron spins onto photon polarizations. We propose a scheme for the production of entangled four-photon states of GHZ type. From the GHZ state, two fully entangled photons can be obtained by a measurement of two photons in the linear polarization basis, even for quantum dots with observable fine structure splitting for neutral excitons and significant exciton spin decoherence. Because of the interplay of quantum mechanical selection rules and interference, maximally entangled electron pairs are converted into maximally entangled photon pairs with unity fidelity for a continuous set of observation directions. We describe the dynamics of the conversion process using a master-equation approach and show that the implementation of our scheme is feasible with current experimental techniques.Comment: 5 pages, 2 figures. v2: Extended scheme, revised version. v3: Minor additions and extended title, published versio