Dynamic grid adaption using the LPE equation

This thesis describes the development and implementation of a dynamic adaptive grid method for general two and three dimensional static and transient fluid flow problems solved over structured grids. The technique automatically manipulates the location of grid points within the domain of interest to concentrate cells in regions of high solution activity, thus aiming to improve the accuracy of the overall simulation for a given number of initial grid cells. To achieve this aim the Laplace Poisson Equidistribution equation is used. Furthermore, the work also covers different types and treatment of weight functions needed to represent areas of high solution activity and a range of techniques necessary to make the use of adaptive grids practical, including geometry modelling and grid quality control. The technique is implemented on simple functions and within the commercial CFD code PHOENICS, on fluid flow problems ranging from convection driven flows to shock capturing. The ability of the technique to be used for general grid manipulation is demonstrated by using it to couple PHOENICS with a stress code in the simulation of a deflecting beam in a uniform flow. In addition, a novel technique to adapt grids to solution phenomena using neural nets is demonstrated

Observations on the ex situ perfusion of livers for transplantation.

Normothermic ex situ liver perfusion might allow viability assessment of livers before transplantation. Perfusion characteristics were studied in 47 liver perfusions, of which 22 resulted in transplants. Hepatocellular damage was reflected in the perfusate transaminase concentrations, which correlated with posttransplant peak transaminase levels. Lactate clearance occurred within 3 hours in 46 of 47 perfusions, and glucose rose initially during perfusion in 44. Three livers required higher levels of bicarbonate support to maintain physiological pH, including one developing primary nonfunction. Bile production did not correlate with viability or cholangiopathy, but bile pH, measured in 16 of the 22 transplanted livers, identified three livers that developed cholangiopathy (peak pH 7.5). In the 11 research livers where it could be studied, bile pH > 7.5 discriminated between the 6 livers exhibiting >50% circumferential stromal necrosis of septal bile ducts and 4 without necrosis; one liver with 25-50% necrosis had a maximum pH 7.46. Liver viability during normothermic perfusion can be assessed using a combination of transaminase release, glucose metabolism, lactate clearance, and maintenance of acid-base balance. Evaluation of bile pH may offer a valuable insight into bile duct integrity and risk of posttransplant ischemic cholangiopathy

Variation in Establishment Success for American Mistletoe [\u3ci\u3ePhoradendron leucarpum\u3c/i\u3e (Raf.) Reveal & M.C. Johnst. (Viscaceae)] Appears Most Likely to Predict its Distribution in Virginia and North Carolina, United States

Dispersal limitation and variation in habitat suitability may determine an association of American mistletoe [Phoradendron leucarpum (Raf.) Reveal & M.C. Johnst. (Viscaceae)] with forested wetlands in Virginia and North Carolina, United States. Here, we first tested the alternative hypothesis that variation in host availability drives this habitat relationship. We used a generalized linear model to show a positive effect of forested wetland habitat on American mistletoe occurrence after accounting for both variation in host availability and differences among regions in host use. We then used seed sowing experiments to quantify how light availability and flood regime determine the viability of American mistletoe, allowing us to evaluate the potential for establishment limitation to determine this habitat relationship. Light availability predicted establishment rates but % canopy openness did not predict seed germination rates. Thus, variation in the ability for American mistletoe to establish across forested habitat types with different local light availabilities is a potentially important mechanism in determining its distribution

26-hour Storage of a Declined Liver Before Successful Transplantation Using Ex Vivo Normothermic Perfusion.

This is the author accepted manuscript. The final version is available at http://dx.doi.org/10.1097/SLA.000000000000183

Normothermic perfusion in the assessment and preservation of declined livers prior to transplantation: hyperoxia and vasoplegia - important lessons from the first 12 cases.

BACKGROUND: A programme of normothermic ex situ liver perfusion (NESLiP) was developed to facilitate better assessment and use of marginal livers, while minimising cold ischaemia. METHODS: Declined marginal livers and those offered for research were evaluated. NESLiP was performed using an erythrocyte-based perfusate. Viability was assessed with reference to biochemical changes in the perfusate. RESULTS: 12 livers (9 from circulatory death (DCD) and 3 from brain-dead donors), median Donor Risk Index 2.15, were subjected to NESLiP for a median 284 minutes (range 122-530) after an initial cold storage period of 427 minutes (range 222-877). The first 6 livers were perfused at high perfusate oxygen tensions, and the subsequent 6 at near-physiologic oxygen tensions. After transplantation, 5 of the first 6 recipients developed postreperfusion syndrome and 4 had sustained vasoplegia; 1 recipient experienced primary nonfunction in conjunction with a difficult explant. The subsequent 6 liver transplants, with livers perfused at lower oxygen tensions, reperfused uneventfully. Three DCD liver recipients developed cholangiopathy, and this was associated with an inability to produce an alkali bile during NESLiP. CONCLUSIONS: NESLiP enabled assessment and transplantation of 12 livers that may otherwise not have been used. Avoidance of hyperoxia during perfusion may prevent postreperfusion syndrome and vasoplegia, and monitoring biliary pH, rather than absolute bile production, may be important in determining the likelihood of posttransplant cholangiopathy. NESLiP has the potential to increase liver utilization, but more work is required to define factors predicting good outcomes.This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

Measurements of the pp → ZZ production cross section and the Z → 4ℓ branching fraction, and constraints on anomalous triple gauge couplings at √s = 13 TeV

Four-lepton production in proton-proton collisions, pp -> (Z/gamma*)(Z/gamma*) -> 4l, where l = e or mu, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb(-1). The ZZ production cross section, sigma(pp -> ZZ) = 17.2 +/- 0.5 (stat) +/- 0.7 (syst) +/- 0.4 (theo) +/- 0.4 (lumi) pb, measured using events with two opposite-sign, same-flavor lepton pairs produced in the mass region 60 4l) = 4.83(-0.22)(+0.23) (stat)(-0.29)(+0.32) (syst) +/- 0.08 (theo) +/- 0.12(lumi) x 10(-6) for events with a four-lepton invariant mass in the range 80 4GeV for all opposite-sign, same-flavor lepton pairs. The results agree with standard model predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZ. couplings at 95% confidence level: -0.0012 < f(4)(Z) < 0.0010, -0.0010 < f(5)(Z) < 0.0013, -0.0012 < f(4)(gamma) < 0.0013, -0.0012 < f(5)(gamma) < 0.0013

Search for the production of dark matter in association with top-quark pairs in the single-lepton final state in proton-proton collisions at √s=8 TeV

Peer reviewe

Searches for supersymmetry using the M-T2 variable in hadronic events produced in pp collisions at 8 TeV

Peer reviewe