Aspects of Supersymmetric Gauge Theories in Two and Three Dimensions

In this thesis we study two- and three-dimensional supersymmetric gauge theories, in particular 2d $\mathcal{N}=(2,2)$ and 3d $\mathcal{N}=4$ theories. The techniques of supersymmetric localization and the Jeffrey-Kirwan residue are applied to compute correlation functions in these theories. Using the localization result for the correlation functions of 2d $\mathcal{N}=(2,2)$ Gauged Linear Sigma Models (GLSMs) on the Omega-deformed two-sphere, we examine the correlation functions of a GLSM describing a non-compact geometry. We investigate the ambiguity in the results for three-point correlators using twisted masses and the Omega deformation, and we compare with previous evaluations of these correlation functions in the literature. For 3d $\mathcal{N}=4$ $U(N)$ theories, by combining inputs from supersymmetric localization and brane constructions in type IIB string theory, we compute correlation functions of monopole operators that are inserted in an Omega background. We study various examples of correlators involving the product of monopoles of minimal positive and negative charges, and investigate the effects of monopole bubbling and wall-crossing phenomena. Our results are successfully tested using the non-commutative Moyal (star) product and the action of Parity-Time (PT) symmetry

Crowdfunding our health: economic risks and benefits

Crowdfunding is an expanding form of alternative financing that is gaining traction in the health sector. This article presents a typology for crowdfunded health projects and a review of the main economic benefits and risks of crowdfunding in the health market. We use evidence from a literature review, complimented by expert interviews, to extend the fundamental principles and established theories of crowdfunding to a health market context. Crowdfunded health projects can be classified into four types according to the venture's purpose and funding method. These are projects covering health expenses, fundraising health initiatives, supporting health research, or financing commercial health innovation. Crowdfunding could economically benefit the health sector by expanding market participation, drawing money and awareness to neglected health issues, improving access to funding, and fostering project accountability and social engagement. However, the economic risks of health-related crowdfunding include inefficient priority setting, heightened financial risk, inconsistent regulatory policies, intellectual property rights concerns, and fraud. Theorized crowdfunding behaviours such as signalling and herding can be observed in the market for health-related crowdfunding. Broader threats of market failure stemming from adverse selection and moral hazard also apply. Many of the discussed economic benefits and risks of crowdfunding health campaigns are shared more broadly with those of crowdfunding projects in other sectors. Where crowdfunding health care appears to diverge from theory is the negative externality inefficient priority setting may have towards achieving broader public health goals. Therefore, the market for crowdfunding health care must be economically stable, as well as designed to optimally and equitably improve public health

The UK’s referendum and post-fact politics: how can campaigners be held accountable for their claims?

Both sides of the UK’s EU referendum campaign were criticised for presenting misleading information to the public. Alan Renwick, Matthew Flinders and Will Jennings write that the referendum highlighted the inability of the British political system to enforce standards of factual accuracy in how politicians campaign. They argue that while legal or regulatory changes could alter this picture to some extent, the real issue is a cultural one

Quantized Coulomb Branches, Monopole Bubbling and Wall-Crossing Phenomena in 3d N=4 Theories

To study the quantized Coulomb branch of 3d N = 4 unitary SQCD theories, we propose a new method to compute correlators of monopole and Casimir operators that are inserted in the R×R2ε Omega background. This method combines results from supersymmetric localization with inputs from the brane realisation of the correlators in type IIB string theory. The main challenge is the computation of the partition functions of certain Super-Matrix-Models (SMMs), which appear in the contribution of monopole bubbling sectors and are realised as the theory living on the D1 strings in the brane construction. We find that the non-commutativity arising in the monopole operator insertions is related to a wall-crossing phenomenon in the FI parameter space of the SMM. We illustrate our method in various examples and we provide explicit results for arbitrary correlators of non-bubbling bare monopole operators. We also discuss the realisation of the non-commutative product as a Moyal (star) product and use it to successfully test our results

The radiology of the complications of warfarin therapy - a pictorial review

Summary This article aims to teach about the complications of warfarin therapy through radiological imaging and highlight the importance of radiology in diagnosing challenging cases. Relevance Warfarin is the most widely used anticoagulant worldwide and is vital in the treatment of many conditions. However, the use of warfarin increases one’s risk of bleeding which can have potentially fatal consequences. It is vital that the complications of warfarin use are considered as part of the differential diagnosis when a patient presents with unexplained symptoms, as quickly diagnosing an acute bleed will improve outcomes. Take Home Messages Complications of warfarin therapy can present in a variety of ways, not always associated with trauma, with potentially dangerous consequences. Radiological investigations are one of the best ways to confirm the diagnosis and so should always be considered to aid diagnosis and treatment

Cost-effectiveness of cancer drugs: comparative analysis of the United States and England

Background England's National Institute for Health and Care Excellence (NICE) and the US’ Institute for Clinical and Economic Review (ICER) both conduct cost-effectiveness evaluations for new cancer drugs to help payers make drug coverage decisions. However, NICE and ICER assessments have been noted to reach different conclusions. We aim to better understand the degree to which their recommendations diverge and what drives these apparent differences. Methods We compared the methods and results of publicly available cost-effectiveness evaluations performed by ICER and NICE of similarly assessed cancer drugs. Assessments were compared based on incremental cost-effectiveness ratio, comparator treatment, price, recommendation, and the design of the economic evaluation. Findings Among 11 commonly assessed cancer drugs, ICER and NICE were in concordance for 7 evaluations and in discordance on the cost-effectiveness and coverage decisions for 4 drugs. Most new cancer drugs were not cost-effective in either the US (7/11) or England (7/11). Furthermore, NICE's capacity to negotiate price discounts and access schemes result in much lower cost per QALY valuations and more favourable recommendations than those of ICER for similarly assessed cancer drugs. Interpretations NICE and ICER employ similar health technology assessment (HTA) methodologies and were aligned with most recommendations, finding that many new and expensive cancer drugs are cost ineffective. Growing use of ICER assessments will continue to send stronger price signals to manufacturers that cancer drugs with low value for money will be viewed less favourably by private insurers. NICE provides an important reminder of how much lower other countries pay for drugs when comparative effectiveness and value-based pricing are integrated into public drug coverage decisions

Structural equation model for estimating risk factors in type 2 diabetes mellitus in a Middle Eastern setting: evidence from the STEPS Qatar.

AIMS: Understanding type 2 diabetes mellitus is critical for designing effective diabetes prevention policies in Qatar and the Middle East. METHODS: Using the Qatar 2012 WHO STEPwise approach to surveillance survey, a subsample of 1224 Qatari participants aged 18-64 years was selected. Subjects had their fasting blood glucose levels tested, had not been diagnosed with or treated for diabetes, had a fasting time >12 hours and were not pregnant. We applied a hypothesized structural equation model (SEM) to assess sociodemographic, behavioral, anthropometric and metabolic variables affecting persons with type 2 diabetes mellitus. RESULTS: There is a direct effect of triglyceride levels (0.336) and body mass index (BMI) (0.164) on diabetes status. We also found that physical activity levels negatively affect BMI (-0.148) and positively affect high-density lipoprotein (HDL) (0.106); sociodemographic background negatively affects diet (-0.522) and BMI (-0.352); HDL positively affects total cholesterol (0.230) and has a negative effect on BMI (-0.108), triglycerides (-0.128) and waist circumference (-0.104). Diet has a positive effect on triglycerides (0.281) while family history of diabetes negatively affects total cholesterol (-0.104). BMI has a positive effect on waist circumference (0.788) and mediates the effects of physical activity over diabetes status (-0.028). BMI also mediates the effects that sociodemographic factors (-0.058) and physical activity (-0.024) have on diabetes status. BMI and HDL (-0.002) together mediate the effect of physical activity on diabetes status and similarly HDL and tryglycerides (-0.005) also mediate the effect of physical activity on diabetes status. Finally diet and tryglycerides mediate the effects that sociodemographic factors have on diabetes status (-0.049). CONCLUSIONS: This study's main finding is that triglyceride levels and BMI are the main variables directly affecting diabetes status in the Qatari population

Long-Term Crop Rotation Diversification Enhances Maize Drought Resistance Through Soil Organic Matter

Climate change adaptation requires building agricultural system resilience to warmer, drier climates. Increasing temporal plant diversity through crop rotation diversification increases yields of some crops under drought, but its potential to enhance crop drought resistance and the underlying mechanisms remain unclear. We conducted a drought manipulation experiment using rainout shelters embedded within a 36-year crop rotation diversity and no-till experiment in a temperate climate and measured a suite of soil and crop developmental and eco-physiological traits in the field and laboratory. We show that diversifying maize-soybean rotations with small grain cereals and cover crops mitigated maize water stress at the leaf and canopy scales and reduced yield losses to drought by 17.1 ± 6.1%, while no-till did not affect maize drought resistance. Path analysis showed a strong correlation between soil organic matter and lower maize water stress despite no significant differences in soil organic matter between rotations or tillage treatments. This positive relationship between soil organic matter and maize water status was not mediated by higher soil water retention or infiltration as often hypothesized, nor differential depth of root water uptake as measured with stable isotopes, suggesting that other mechanisms are at play. Crop rotation diversification is an underappreciated drought management tool to adapt crop production to climate change through managing for soil organic matter