Metastable Flux Configurations and de Sitter Spaces

We derive stability conditions for the critical points of the no-scale scalar potential governing the dynamics of the complex structure moduli and the axio-dilaton in compactifications of type IIB string theory on Calabi-Yau three-folds. We discuss a concrete example of a T^6 orientifold. We then consider the four-dimensional theory obtained from compactifications of type IIB string theory on non-geometric backgrounds which are mirror to rigid Calabi-Yau manifolds and show that the complex structure moduli fields can be stabilized in terms of H_{RR} only, i.e. with no need of orientifold projection. The stabilization of all the fields at weak coupling, including the axio-dilaton, may require to break supersymmetry in the presence of H_{NS} flux or corrections to the scalar potential.Comment: 24 page

First principles electronic and elastic properties of fresnoite Ba2TiSi2O8 (article)

This is the final version of the article. Available from IOP Publishing via the DOI in this record.The research materials supporting this publication can be accessed in ORE at http://hdl.handle.net/10871/30403Electronic, structural and elastic properties of fresnoite, Ba2TiSi2O8 (BTSO), are obtained via first principles calculations. The electronic properties having been comparatively analysed using both the generalised gradient approximation and the hybrid functional method. The indirect band gap of BTSO is found to change significantly through the choice of functional; it shows an increase from 3.79 eV to 5.72 eV. A small indirect gap of 0.33 eV is also present directly above the conduction band edge, which allows for small optical transitions similar to that of defect transitions. The titanium orbitals are dominant near the conduction band edge, with oxygen orbitals being the main contributor to the valence band edge. Dielectric and elastic properties of the material are also obtained, with the bulk modulus being 131.73 GPa and the elastic moduli along the [1 0 0] and [0 0 1] directions being 180.57 GPa and 102.56 GPa, respectively. Theoretical values for Raman frequencies are reported for BTSO. Finally, Bader charge analysis reveals the barium and titanium atoms in BTSO are comparable to their charges in BaTiO3. However, due to the presence of the Si–O bonds, oxygen exhibits a significant charge redistribution. Through the choice of functional, charge can become more localised on the oxygen atoms.Via our membership of the UK's HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service (www.archer.ac.uk). We acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom, via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1)

Ultra-fast sampling of terahertz pulses from a quantum cascade laser using superconducting antenna-coupled NbN and YBCO detectors

We demonstrate the ultra-fast detection of terahertz pulses from a quantum cascade laser (QCL) using superconducting NbN and YBCO detectors. This has enabled both the intrapulse and interpulse dynamics of a THz QCL to be measured directly, including interpulse heating effects on sub-μs timescales

Determinants of Perinatal Outcomes in Dialyzed and Transplanted Women in Australia.

Introduction: Drivers of adverse perinatal outcomes in pregnancies of women receiving chronic kidney replacement therapy (KRT) remain poorly understood. Methods: Births ≥ 20 weeks of gestation in Australian women receiving KRT were analyzed for perinatal outcomes stratified by maternal KRT exposure (dialysis or transplant, analyzed separately), by linking the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) and perinatal data sets (1991-2013). Results: Of 2,948,084 babies (1,628,181 mothers), 248 were born to mothers receiving KRT (transplant, n = 211; dialysis, n = 37), with live birth rates ≥ 94%. The perinatal death rate was 162, 62, and 9 per 1000 births in the dialysis, transplant, and non-KRT cohorts, respectively. Babies exposed to KRT had increased odds of prematurity, small-for-gestational age (SGA), poor birth condition, resuscitation, intensive care admission, and longer hospitalization, with the dialysis cohort having worse outcomes. Preterm babies of dialyzed and transplanted mothers (compared with preterm babies with no KRT exposure) experienced 1.6- to 2.7-fold higher odds for all adverse outcomes, except birthweight 10-fold higher odds of preterm birth and low birthweight and 1.8- to 4.6-fold increased odds of other adverse outcomes. In transplanted women, mediation analysis revealed that pregnancy-induced hypertension contributed only a modest proportional effect (2.5%-11.2%) on adverse outcomes. Conclusion: Maternal dialysis and transplantation conferred excess perinatal morbidity, particularly for preterm babies, and even in women with good preconception allograft function. Pregnancy-induced hypertension is not the predominant determinant of perinatal morbidity. Preconception counseling of women with kidney disease should encompass discussion of perinatal complications

In-home dementia caregiving is associated with greater psychological burden and poorer mental health than out-of-home caregiving: a cross-sectional study

Introduction: Caregivers who live with a person with dementia who receives care, compared with those who live elsewhere, are often considered to experience greater levels of psychological and affective burden. The evidence for this is, however, only limited to studies employing small sample sizes and that failed to examine caregivers’ psychological wellbeing. We address these issues in a large cohort of dementia caregivers. // Methods: We conducted a cross-sectional study comparing caregivers living with a dementia care recipient (n = 240) to caregivers living elsewhere (n = 255) on caregivers’ burden, anxiety, and depression. // Results: We found that caregivers living with the care recipient relative to those living elsewhere showed significantly greater burden and depression, but we found no group difference in anxiety. // Conclusions: Our study adds to the evidence by showing that cohabiting with a care recipient with dementia is associated with greater burden and poorer psychological wellbeing. Strategies aiming to improve caregivers’ burden and psychological wellbeing should take account of caregivers’ living arrangements

How to select varieties for organic farming: science and practice

Selection of cereal varieties suited to organic farming requires a different, butcomplementary, approach to that used when developing cereals for conventional high input systems. Selection is based on the interaction between a series of desirable plant and crop characteristics, in particular competitive ability against weeds. Certain key characteristics that are generically desirable for organic cereal varieties include: (1) good establishment ability, (2) high tillering ability, (3) increasing plant height, (4) planophile leaf habit, (5) high leaf index and (6) robustnesses in yield performance across sites.Our data strongly suggest that high crop ground cover is the most important feature for creating a highly competitive crop that also has consistency in yield. Individual plant or crop traits in (1) to (5) can be used to define plant growth habits. A scheme for assessing growth habits in new varieties is presented