A semi-implicit version of the MPAS-atmosphere dynamical core

An important question for atmospheric modeling is the viability of semi-implicit time integration schemes on massively parallel computing architectures. Semi-implicit schemes can provide increased stability and accuracy. However, they require the solution of an elliptic problem at each time step, creating concerns about their parallel efficiency and scalability. Here, a semi-implicit (SI) version of the Model for Prediction Across Scales (MPAS) is developed and compared with the original model version, which uses a split Runge-Kutta (SRK3) time integration scheme. The SI scheme is based on a quasi-Newton iteration toward a Crank-Nicolson scheme. Each Newton iteration requires the solution of a Helmholtz problem; here, the Helmholtz problem is derived, and its solution using a geometric multigrid method is described. On two standard test cases, a midlatitude baroclinic wave and a small-planet nonhydrostatic gravity wave, the SI and SRK3 versions produce almost identical results. On the baroclinic wave test, the SI version can use somewhat larger time steps (about 60%) than the SRK3 version before losing stability. The SI version costs 10%-20% more per step than the SRK3 version, and the weak and strong scalability characteristics of the two versions are very similar for the processor configurations the authors have been able to test (up to 1920 processors). Because of the spatial discretization of the pressure gradient in the lowest model layer, the SI version becomes unstable in the presence of realistic orography. Some further work will be needed to demonstrate the viability of the SI scheme in this case.UK Natural Environment Research Council as part of the G8 ICOMEX projec

Section on Prospects for Dark Matter Detection of the White Paper on the Status and Future of Ground-Based TeV Gamma-Ray Astronomy

This is a report on the findings of the dark matter science working group for the white paper on the status and future of TeV gamma-ray astronomy. The white paper was commissioned by the American Physical Society, and the full white paper can be found on astro-ph (arXiv:0810.0444). This detailed section discusses the prospects for dark matter detection with future gamma-ray experiments, and the complementarity of gamma-ray measurements with other indirect, direct or accelerator-based searches. We conclude that any comprehensive search for dark matter should include gamma-ray observations, both to identify the dark matter particle (through the charac- teristics of the gamma-ray spectrum) and to measure the distribution of dark matter in galactic halos.Comment: Report from the Dark Matter Science Working group of the APS commissioned White paper on ground-based TeV gamma ray astronomy (19 pages, 9 figures

Effect of superficial treatment with new natural antioxidant on salmon (Salmo salar) lipid oxidation

Lipid oxidation is one of the main factors responsible for the quality loss in refrigerated and frozen stored fish products. The aim of the study was to evaluate the effect of superficial treatment of Atlantic salmon (Salmo salar) with dihydroquercetin (DHQ) solutions on the hydrolytic and oxidative changes in fish lipids during refrigerated storage. It was found that treatment with DHQ solution (1.0 g l−1) reduced approximately twice the free fatty acids content of chilled stored salmon. After 11 days of storage at 1 °С, the contents of hydroperoxides (HPO) and 2-thiobarbituric acid reactive substances (TBARS) of these samples decreased with 45.00 and 0.91 mg MDA/kg, respectively. The share of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) in control and experimental samples did not differ significantly (P>0.05). Results obtained show that the superficial treatment of salmon with DHQ solution (1.0 g l−1) delayed the hydrolytic and oxidative changes in fish lipids significantly, thus preserving the salmon freshness up to 11 days of storage at 1 °С

Squeezed between shells? On the origin of the Lupus I molecular cloud. - II. APEX CO and GASS HI observations

Accepted for publication in a future issue of Astronomy & Astrophysics. Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO.Context. The Lupus I cloud is found between the Upper-Scorpius (USco) and the Upper-Centaurus-Lupus (UCL) sub-groups of the Scorpius-Centaurus OB-association, where the expanding USco H I shell appears to interact with a bubble currently driven by the winds of the remaining B-stars of UCL. Aims. We investigate if the Lupus I molecular could have formed in a colliding flow, and in particular, how the kinematics of the cloud might have been influenced by the larger scale gas dynamics. Methods. We performed APEX 13CO(2–1) and C 18O(2–1) line observations of three distinct parts of Lupus I that provide kinematic information on the cloud at high angular and spectral resolution. We compare those results to the atomic hydrogen data from the GASS H i survey and our dust emission results presented in the previous paper. Based on the velocity information, we present a geometric model for the interaction zone between the USco shell and the UCL wind bubble. Results. We present evidence that the molecular gas of Lupus I is tightly linked to the atomic material of the USco shell. The CO emission in Lupus I is found mainly at velocities between vLSR = 3–6 km s−1 which is in the same range as the H i velocities. Thus, the molecular cloud is co-moving with the expanding USco atomic H i shell. The gas in the cloud shows a complex kinematic structure with several line-of-sight components that overlay each other. The non-thermal velocity dispersion is in the transonic regime in all parts of the cloud and could be injected by external compression. Our observations and the derived geometric model agree with a scenario where Lupus I is located in the interaction zone between the USco shell and the UCL wind bubble. Conclusions. The kinematics observations are consistent with a scenario where the Lupus I cloud formed via shell instabilities. The particular location of Lupus I between USco and UCL suggests that counter-pressure from the UCL wind bubble and pre-existing density enhancements, perhaps left over from the gas stream that formed the stellar subgroups, may have played a role in its formation.Peer reviewedFinal Accepted Versio

Research protocol: investigating the feasibility of a group self-management intervention for stroke (the GUSTO study)

Background: Life after stroke can be an ongoing struggle with over half of all survivors reporting unmet emotional and social needs. In the United Kingdom's (UK) national clinical guidelines for stroke, self-management is suggested as one approach which can support long-term needs. In the UK NHS, self-management interventions are delivered in various ways. Regardless of the delivery mechanism, a tailored approach and ways to integrate peer support are advocated. Group delivery offers a platform for peer support and has the potential to remain individualised. However, before the efficacy of a group self-management intervention can be tested, the feasibility must be explored. This research investigates the feasibility of a GroUp Self-management intervention for sTrOke (GUSTO). Methods: A randomised waitlist control design will be used to investigate the feasibility of a group self-management intervention adapted from an existing one-to-one intervention called Bridges. A mixed methods approach will be used. Qualitative work will capture participant experience, while quantitative work will allow preliminary comparison between the intervention and waitlist groups (between subjects) and pre-post intervention measures (within subjects). Interviews will be conducted with stroke survivors and focus groups with family and friends to assess acceptability of the intervention. Discussion: There is a growing interest in group-based self-management interventions for stroke as a method of supporting stroke survivors' ongoing unmet needs. This is an area with limited research to date. This study will inform design of a fully powered trial which would assess the efficacy of a group self-management intervention following stroke. Trial registration: ISRCTN19867168

Structural analysis of MDM2 RING separates degradation from regulation of p53 transcription activity

MDM2–MDMX complexes bind the p53 tumor-suppressor protein, inhibiting p53's transcriptional activity and targeting p53 for proteasomal degradation. Inhibitors that disrupt binding between p53 and MDM2 efficiently activate a p53 response, but their use in the treatment of cancers that retain wild-type p53 may be limited by on-target toxicities due to p53 activation in normal tissue. Guided by a novel crystal structure of the MDM2–MDMX–E2(UbcH5B)–ubiquitin complex, we designed MDM2 mutants that prevent E2–ubiquitin binding without altering the RING-domain structure. These mutants lack MDM2's E3 activity but retain the ability to limit p53′s transcriptional activity and allow cell proliferation. Cells expressing these mutants respond more quickly to cellular stress than cells expressing wild-type MDM2, but basal p53 control is maintained. Targeting the MDM2 E3-ligase activity could therefore widen the therapeutic window of p53 activation in tumors