4 research outputs found
Fluxes and Branes in Type II Vacua and M-theory Geometry with G(2) and Spin(7) Holonomy
We discuss fluxes of RR and NSNS background fields in type II string
compactifications on non-compact Calabi-Yau threefolds together with their dual
brane description which involves bound states of branes. Simultaneously turning
on RR and NSNS 2-form fluxes in an 1/2 supersymmetric way can be geometrically
described in M-theory by a SL(2,Z) family of metrics of G(2) holonomy. On the
other hand, if the flux configuration only preserves 1/4 of supersymmetries, we
postulate the existence of a new eight-dimensional manifold with spin(7)
holonomy, which does not seem to fit into the classes of known examples. The
latter situation is dual to a 1/4 supersymmetric web of branes on the deformed
conifold. In addition to the 2-form fluxes, we also present some considerations
on type IIA NSNS 4-form and 6-form fluxes.Comment: 34 pages, latex, no figures, changed appendix on Spin(7) metrics,
more references adde
Heterotic twistor-string theory
We reformulate twistor-string theory as a heterotic string based on a twisted
(0,2) model. The path integral localizes on holomorphic maps, while the (0,2)
moduli naturally correspond to the states of N=4 super Yang-Mills and conformal
supergravity under the Penrose transform. We show how the standard
twistor-string formulae of scattering amplitudes as integrals over the space of
curves in supertwistor space may be obtained from our model. The corresponding
string field theory gives rise to a twistor action for N=4 conformal
supergravity coupled to super Yang-Mills. The model helps to explain how the
twistor-strings of Witten and Berkovits are related and clarifies various
aspects of each of these models.Comment: 45 page
Four consecutive yearly point-prevalence studies in Wales indicate lack of improvement in sepsis care on the wards
The ‘Sepsis Six’ bundle was promoted as a deliverable tool outside of the critical care settings, but there is very little data available on the progress and change of sepsis care outside the critical care environment in the UK. Our aim was to compare the yearly prevalence, outcome and the Sepsis Six bundle compliance in patients at risk of mortality from sepsis in non-intensive care environments. Patients with a National Early Warning Score (NEWS) of 3 or above and suspected or proven infection were enrolled into four yearly 24-h point prevalence studies, carried out in fourteen hospitals across Wales from 2016 to 2019. We followed up patients to 30 days between 2016–2019 and to 90 days between 2017 and 2019. Out of the 26,947 patients screened 1651 fulfilled inclusion criteria and were recruited. The full ‘Sepsis Six’ care bundle was completed on 223 (14.0%) occasions, with no significant difference between the years. On 190 (11.5%) occasions none of the bundle elements were completed. There was no significant correlation between bundle element compliance, NEWS or year of study. One hundred and seventy (10.7%) patients were seen by critical care outreach; the ‘Sepsis Six’ bundle was completed significantly more often in this group (54/170, 32.0%) than for patients who were not reviewed by critical care outreach (168/1385, 11.6%; p < 0.0001). Overall survival to 30 days was 81.7% (1349/1651), with a mean survival time of 26.5 days (95% CI 26.1–26.9) with no difference between each year of study. 90-day survival for years 2017–2019 was 74.7% (949/1271), with no difference between the years. In multivariate regression we identified older age, heart failure, recent chemotherapy, higher frailty score and do not attempt cardiopulmonary resuscitation orders as significantly associated with increased 30-day mortality. Our data suggests that despite efforts to increase sepsis awareness within the NHS, there is poor compliance with the sepsis care bundles and no change in the high mortality over the study period. Further research is needed to determine which time-sensitive ward-based interventions can reduce mortality in patients with sepsis and how can these results be embedded to routine clinical practice