Measurement of the t(t^-) cross-section at 7 TeV with 36 PB-1 of data in the electron+jets decay channel using the CMS detector

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.A measurement of the top-pair production cross-section at a centre-of-mass energy of 7 TeV using proton-proton collisions with 36 pb-1 of data collected by CMS at the Large Hadron Collider is presented. The analysis is performed using the nal state that consists of one isolated electron with jets, one of which is required to be identified as being consistent with including the decay of a B hadron. The measured cross-section with three or more selected jets is 169 +/- 13(stat:)+37 +32(sys:)+8 -7(lumi:) pb and 197 +/- 17(stat:)+38 -35(sys:)+9 -8(lumi:) pb for four or more jets. The results are consistent with NLO and approximate NNLO theoretical predictions.This study is supported by the Science and Technologies Funding Council

Reconstructing Antarctic sea ice from 130,000 years ago

Past warm periods serve as an analog for the impacts of future warming. Reconstructions of Antarctic sea ice from 130,000 years ago show a reduction in sea-ice extent relative to the present, with the patterns of retreat varying between regions of the Southern Ocean

V1: Targeting and Scaling Out

Numerous pilot studies and case studies in the Volta Basin have evaluated practices, methods, and tools that could prove beneficial to others, both within the basin and outside of it. However, the question whether an intervention successfully applied in one location has a reasonable chance of success at any other location remains extremely difficult to answer. A consistent finding in pilot studies is that detailed characteristics of the study location – economic, biophysical, institutional, and cultural – can all play an essential role in the eventual success, and failure of achieving a successful outcome. For out-scaling of initiatives it is impractical to collect detailed information at every potential site where an agricultural land and water management (AWM) intervention might be introduced. This project starts with the premise that, while certainty is unobtainable, degrees of certainty are both obtainable, using available information in a systematic way, and useful.The CPWF Project V1, “Targeting and Scaling Out”, proposal aims to develop an evidence and knowledge-based tool that will map the likelihood that a given intervention will be successful in given locations. The proposed V1 project will contribute to achieving the BDC challenge of improving rainwater and small reservoir management to contribute to poverty reduction and improved livelihoods resilience by producing a framework and web-based and electronic “decision support”, (or targeting and scaling out tool) that will identify likely sites to introduce AWM interventions for smallholder farming systems

The 2016 Reactivations of Main-Belt Comets 238P/Read and 288P/(300163) 2006 VW139

We report observations of the reactivations of main-belt comets 238P/Read and 288P/(300163) 2006 VW139, that also track the evolution of each object's activity over several months in 2016 and 2017. We additionally identify and analyze archival SDSS data showing 288P to be active in 2000, meaning that both 238P and 288P have now each been confirmed to be active near perihelion on three separate occasions. From data obtained of 288P from 2012-2015 when it appeared inactive, we find best-fit R-band H,G phase function parameters of H_R=16.80+/-0.12 mag and G_R=0.18+/-0.11, corresponding to effective component radii of r_c=0.80+/-0.04 km, assuming a binary system with equally-sized components. Fitting linear functions to ejected dust masses inferred for 238P and 288P soon after their observed reactivations in 2016, we find an initial average net dust production rate of 0.7+/-0.3 kg/s and a best-fit start date of 2016 March 11 (when the object was at a true anomaly of -63 deg) for 238P, and an initial average net dust production rate of 5.6+/-0.7 kg/s and a best-fit start date of 2016 August 5 (when the object was at a true anomaly of -27 deg) for 288P. Applying similar analyses to archival data, we find similar start points for previous active episodes for both objects, suggesting that minimal mantle growth or ice recession occurred between the active episodes in question. Some changes in dust production rates between active episodes are detected, however. More detailed dust modeling is suggested to further clarify the process of activity evolution in main-belt comets.Comment: 21 pages, 9 figures, accepted by A

Nano-scale reservoir computing

This work describes preliminary steps towards nano-scale reservoir computing using quantum dots. Our research has focused on the development of an accumulator-based sensing system that reacts to changes in the environment, as well as the development of a software simulation. The investigated systems generate nonlinear responses to inputs that make them suitable for a physical implementation of a neural network. This development will enable miniaturisation of the neurons to the molecular level, leading to a range of applications including monitoring of changes in materials or structures. The system is based around the optical properties of quantum dots. The paper will report on experimental work on systems using Cadmium Selenide (CdSe) quantum dots and on the various methods to render the systems sensitive to pH, redox potential or specific ion concentration. Once the quantum dot-based systems are rendered sensitive to these triggers they can provide a distributed array that can monitor and transmit information on changes within the material.Comment: 8 pages, 9 figures, accepted for publication in Nano Communication Networks, http://www.journals.elsevier.com/nano-communication-networks/. An earlier version was presented at the 3rd IEEE International Workshop on Molecular and Nanoscale Communications (IEEE MoNaCom 2013

L1: Targeting and scaling out

Despite hosting some of the most developed sub Saharan countries, a majority of rural smallholder farmers in the Limpopo basin still live in poverty. The challenge of low and highly variable rainfall together with inadequate technology transfers, inadequate policy and investment context all act to disable successful transitions out of poverty. The CPWF Phase I identified several opportunities to manage rainfall in more efficient and productive manners at field to basin scales. The challenge of successful targeting and scaling out is still a key research and development area to contribute towards the Limpopo development challenges with opportunities to enable transformations of rural livelihoods at a greater scale. The project L1 ”Targeting and scaling out” aims to develop an evidence and knowledge-based tool that will map the likelihood that a given intervention will be successful in given locations. The tool would be intended for non-expert users and would be available via the World Wide Web. The proposed L1 project will contribute to achieving the BDC challenge of improving rainwater and small reservoir management to contribute to poverty reduction and improved livelihoods resilience. It will do this by producing a framework and web-based and electronic “decision support”, (or targeting and scaling out tool) that will identify likely sites to introduce AWM interventions for smallholder farming systems

3D Printing of Bone Spurs Before Surgical Removal

Project Background: In the US alone, total knee arthroplasty is the most common performed orthopedic surgery, with over 700,000 cases per year.1 Overall, 21-25% underwent revision due to instability.2 The stability of a TKA depends largely on soft tissue balance for proper alignment in flexion and extension. Soft tissue balancing in TKA depends on posterior femoral condylar osteophytes, which prevent full extension of the knee and increase tension posteriorly. Pre-operative soft tissue visualization is difficult and this leaves an increased chance for implant failure and revision surgery. Having a 3D model of the bone spur before and during the surgery may decrease risk of complication and enhance soft tissue modification for proper knee balancing post TKA. Proposed Methods: We will 3D print a knee via MRI or CT that has been de-identified and provided by our mentor. The orthopedic surgeon will use this print out before or during surgery to address any concerns they have during the surgery in terms of proper balancing of the soft tissue of the knee. After approximately 10 uses within the OR, we will interview the surgeons and patients for their feedback. Patients undergoing total knee arthroplasty using the 3D printed knee will be matched with historic records of those who had undergone TKA. Rates of revision, patient satisfaction, and OR time will be compared across groups using chi-square and t-tests where appropriate. Results: We anticipate reduced OR time, increased patient satisfaction and decreased rates of revision. Conclusions: Our study demonstrates an initial use for 3D models as an aid or guide for total knee arthroplasty. Using a 3D model for TKA helps the surgeon visualize osteophytes and reduces the need for revision surgery. A larger study will need to be conducted in order to test the feasibility and practicality of 3D printing for surgery

3D Printing of Knee Models to Decrease OR Time and Reduce Revisional Surgery in Total Knee Arthroplasty (TKA)

Project Background: Osteophytes are a common problem, affecting 2% of the United States population. For many elderly people, these osteophytes will cause them to seek medical attention. Due to the 2-D nature of MRIs and CT scans, it can be difficult to gain a complete understanding of the complicated soft tissue structures surrounding the joint when performing a Total Knee Arthroplasty(TKA). Without proper removal of osteophytes and correct soft tissue balancing, there is an increased rate of revisional surgery. By utilizing a 3-D model preoperatively and within the OR, surgeons can visualize various aspects of the knee to determine what may be contributing to a soft tissue imbalance. Proposed Methods: We plan to conduct a prospective cohort study at the Rothman Institute. We will use CT images to create 3-D printed models of knees complicated with osteophytes. The surgeon will have the model to reference both preoperatively and during the surgery. We will measure the effectiveness of model by collecting data on the total procedural time, the rate of revisional surgery within the next year, and through feedback from the surgeons. Results: Although we do not currently have any results, we anticipate approval for our project shortly. We hope to have data collected within the next few months supporting our hypothesis that 3-D models will decrease both OR time and revisional surgeries. Conclusions: While the literature shows that these 3-D models may help with OR time, we have been unable to verify this yet. Additionally, revisional surgery can happen months later, so this data may be more difficult to collect in our time frame. After the pilot study has been completed, if we have promising results we hope to expand the project to include other types of surgeries affected by soft tissue balancing