Next-to-leading order predictions for WW+jet production

In this work we report on a next-to-leading order calculation of WW + jet production at hadron colliders, with subsequent leptonic decays of the W-bosons included. The calculation of the one-loop contributions is performed using generalized unitarity methods in order to derive analytic expressions for the relevant amplitudes. These amplitudes have been implemented in the parton-level Monte Carlo generator MCFM, which we use to provide a complete next-to-leading order calculation. Predictions for total cross-sections, as well as differential distributions for several key observables, are computed both for the LHC operating at 14 TeV as well as for a possible future 100 TeV proton-proton collider.Comment: 14 pages, 7 figures; v2: several references added, 2 typos corrected. Corresponds to published journal versio

Observing The Hidden Sector

We study the effects of renormalization due to hidden-sector dynamics on observable soft supersymmetry-breaking parameters in the minimal supersymmetric extension of the Standard Model (MSSM), under various hypotheses about their universality at a high input scale. We show that hidden-sector renormalization effects may induce the spurious appearance of unification of the scalar masses at some lower scale, as in mirage unification scenarios. We demonstrate in simple two-parameter models of the hidden-sector dynamics that the parameters may in principle be extracted from experimental measurements, rendering the hidden sector observable. We also discuss the ingredients that would be necessary to carry this programme out in practice.Comment: 38 pages, 13 figures, uses UApreprint.cls and subfigure.sty (included

Responding to a world of change

The BGS is proud of the central role our surveying has played in the development of geology as a science. We are equally proud of our contribution to the understanding of key issues such as the age and evolution of the Earth and life, the origin and classification of rocks, and the impact of humans on the earth system. With 175 years of dedicated surveying behind us, the UK is already better served with geological information than most other countries. However, in today’s rapidly evolving, knowledge-based economy, we must continually adapt our surveying to meet the changing needs of society

T cell activation in Theileria annulata infection: implications for immunity and pathogenesis

Theileria annulata is a protozoan parasite of cattle, causing the lymphoproliferative disease tropica] theileriosis. Ir susceptible animals, disease progresses rapidly, with the host apparently unable to mount an effective immune response. The parasite infects MHC class II+ monocytes and macrophages, during its pathogenic macroschizont stage. This leads to an augmentation of their antigen presenting capability in vitro - infected cells (IC) can induce proliferation of autologous resting T cells from naive animals. Preliminary studies showed that such altered APC function was a barrier to isolating Theileria specific T cells from immune animals. Infection of APC leading to a change in their function may provide T.annulata with a mechanism to evade the host immune response. This thesis sets out to understand interactions between T cells and T. annulata infected cells, both in vitro and in vivo and the consequences for the generation of immunity.In vitro stimulation of peripheral blood T cells from naive animals by IC caused the cells to proliferate, peaking 5 days post stimulation. Phenotypic analysis showed that CD25 and MHC class II were expressed upon the surface of all T cells (CD4.CD8 and 76T cells) within 24hrs of stimulation, reaching a peak at 48hrs and remaining stably expressed for up to 7 days post activation. The parasite infected cells could activate both "memory" and "naive" CD4 T cells, with little change in the CD45RB isoforms during activation. Activation of T cells was contact dependant. T.annulata infected cells can therefore cause the activation of the majority of T cells from naive animals irrespective of memory status and, presumably, antigen specificity.vation of the majority of T cells from naive animals irrespective of memory status and, presumably, antigen specificity. The cytokines produced by IC stimulated T cells 1-7 days post stimulation were assessed by reverse transcription polymerase chain reaction (RT-PCR) using primers for IL2, IL2 receptor (IL2R), IL4 and interferon gamma (IFNy). None of these cytokines were found to be expressed by 1C. T cells within PBM expressed mRNA for IL2, IL2R, IL4 and IFNy 24-48 hours post IC stimulation. IL2 and its receptor were still expressed at day 5 (peak proliferation), and waned by day 7. IFNy was expressed by all tested animals' cells at all timepoints, while IL4 was intermittently found at day 5 and was always absent at day 7. IL4 was only expressed by CD4 T cells, while lL2/IL2R/IFNy was expressed by all T cell types. The presence of CD4 cells was required for 1L2 and IL2R expression by non CD4 T cells.In vivo examination was of the draining lymph node (DLN) which is the principal site of parasite development, ideally placing the parasite to interfere with the induction of immunity. DLN exhibited radically altered distributions of T cells expressing activation markers from accepted steps in immune response development. Infected cells were first manifested as proliferating non T non B cells which disseminated throughout the node and which expressed monocyte surface markers. Medullary T cells (predominantly CD4) clustered around 1C and expressed CD25 within 2 days of infection. This pattern persisted 4 days post infection, but numbers of CD25 T cells subsequently declined and none were found in the node by 10 days post infection. Altered function of DLN T cells was most obvious in the destruction of DLN germinal centres (GC), particularly the T cell dependent light zones. Although T cell activation marker expression waned, CD3 cells were not depleted from GC light zones or from the node in general. This may suggest that soluble factors play a role in interfering with immunity. Cytokine analysis of DLN cells early in infection demonstrated that production of IL4 within the entire node ceased within 4 days of infection, while in contrast IFNy production remained and has been shown in other experiments to become elevated. The control of B cell proliferation and differentiation depends partially upon the balance between stimulatory IL4 and inhibitory IFNy. The dominant production of IFNy may be leading to the disruption observed in GC by both changing the IL4 production capabilities of GC T cells and directly inhibiting B cell differentiation.In summary, this thesis has shown that T.annulata infected cells posses an innate ability to activate naive T cells. Although all T cell types are activated in pbm, this is dependant upon cytokine release by CD4 cells, subsequently leading to a type I response. In vivo, a similar mechanism leads to activation of DLN T cells primarily by IC. Such interactions do not lead to the induction of an antigen specific immune response, but to the loss of GC and suppression of further T cell activation

Managerial Overconfidence and Corporate Policies

Miscalibration is a standard measure of overconfidence in both psychology and economics. Although it is often used in lab experiments, there is scarcity of evidence about its effects in practice. We test whether top corporate executives are miscalibrated, and whether their miscalibration impacts investment behavior. Over six years, we collect a unique panel of nearly 7,000 observations of probability distributions provided by top financial executives regarding the stock market. Financial executives are miscalibrated: realized market returns are within the executives' 80% confidence intervals only 38% of the time. We show that companies with overconfident CFOs use lower discount rates to value cash flows, and that they invest more, use more debt, are less likely to pay dividends, are more likely to repurchase shares, and they use proportionally more long-term, as opposed to short-term, debt. The pervasive effect of this miscalibration suggests that the effect of overconfidence should be explicitly modeled when analyzing corporate decision-making.

Beyond Mixing-length Theory: a step toward 321D

We examine the physical basis for algorithms to replace mixing-length theory (MLT) in stellar evolutionary computations. Our 321D procedure is based on numerical solutions of the Navier-Stokes equations. These implicit large eddy simulations (ILES) are three-dimensional (3D), time-dependent, and turbulent, including the Kolmogorov cascade. We use the Reynolds-averaged Navier-Stokes (RANS) formulation to make concise the 3D simulation data, and use the 3D simulations to give closure for the RANS equations. We further analyze this data set with a simple analytical model, which is non-local and time-dependent, and which contains both MLT and the Lorenz convective roll as particular subsets of solutions. A characteristic length (the damping length) again emerges in the simulations; it is determined by an observed balance between (1) the large-scale driving, and (2) small-scale damping. The nature of mixing and convective boundaries is analyzed, including dynamic, thermal and compositional effects, and compared to a simple model. We find that (1) braking regions (boundary layers in which mixing occurs) automatically appear {\it beyond} the edges of convection as defined by the Schwarzschild criterion, (2) dynamic (non-local) terms imply a non-zero turbulent kinetic energy flux (unlike MLT), (3) the effects of composition gradients on flow can be comparable to thermal effects, and (4) convective boundaries in neutrino-cooled stages differ in nature from those in photon-cooled stages (different P\'eclet numbers). The algorithms are based upon ILES solutions to the Navier-Stokes equations, so that, unlike MLT, they do not require any calibration to astronomical systems in order to predict stellar properties. Implications for solar abundances, helioseismology, asteroseismology, nucleosynthesis yields, supernova progenitors and core collapse are indicated.Comment: 22 pages, 4 figures, 2 tables; significantly re-written, critique of Pasetto, et al. model added, accepted for publication by Ap

A pragmatic multi-centre randomised controlled trial of fluid loading and level of dependency in high-risk surgical patients undergoing major elective surgery : trial protocol

Peer reviewedPublisher PD