Assessing scanning strategies with all-digital phased array weather radars for characterization and detection of microbursts

Microbursts are a rapidly evolving, vertically oriented meteorological phenomena that can be extremely hazardous to aviation, and other human activities, if left undetected. The temporal resolution and vertical sampling of the current operational weather radar network (NEXRAD) is too coarse to properly observe the evolution of microbursts and their precursor signatures. However, a potential polarimetric phased array weather radar (PAR) should be able to improve both temporal resolution and spatial sampling of the atmosphere to provide better observation of rapidly evolving hazards such as microbursts. All-digital PAR technology is extremely flexible as a wide array of scanning techniques are available to use; however, this flexibility is not without trade-offs, and these trade-offs are important for understanding how a potential PAR network would operate. This thesis will lay out a framework and tool set for the study of microbursts and their precursor signatures with varying PAR scanning strategies. This project is the first of its kind to investigate the question of what trade-offs are associated with different scanning strategies when using a planar, mechanically rotating, all-digital PAR to observe and detect microbursts and their precursor signatures, including dual-polarization variables. The scanning strategies analyzed include a traditional volume coverage pattern (VCP) 212, a true range-height indicator (RHI) scan, and imaging at three different spoiled beamwidths in elevation. VCP 212 represents the current operational capacity for microburst observation and detection. True RHI scanning and imaging are more feasible on a PAR system, and they can provide faster temporal resolution and finer vertical sampling. The framework and tools developed herein are tested in a proof-of-concept analysis by looking at a single wet microburst producing storm generated within a numerical weather prediction (NWP) simulation. Using this NWP simulation data, scanning strategies are implemented through the use of a radar emulator, RSim. These emulations are then analyzed both qualitatively and quantitatively to compare the size, shape, and intensity observations of different microburst precursor signatures: descending reflectivity columns (DRCs), specific differential phase (KDP) cores, and mid-level convergence. Because of the use of NWP simulations, error analysis is also performed to characterize the impact of estimation errors. The results of this test case analysis of one wet microburst imply that, when utilizing imaging, there is a limit to the benefits provided by increased temporal resolution. This limit occurs at temporal resolutions equal to 30 s and an imaging spoil factor of 5 degrees. When utilizing any spoil factor larger than 5 degrees , the effects of data degradation become too great for the scanning strategy to overcome, the representativeness of the model environment is degraded, and estimation errors become large. However, these results can only be considered preliminary because the analysis only serves as a proof-of-concept

Differential Resistance of Borrelia burgdorferi Clones to Human Serum-Mediated Killing Does Not Correspond to Their Predicted Invasiveness

Reservoir host associations have been observed among and within Borrelia genospecies, and host complement-mediated killing is a major determinant in these interactions. In North America, only a subset of Borrelia burgdorferi lineages cause the majority of disseminated infections in humans. We hypothesize that differential resistance to human complement-mediated killing may be a major phenotypic determinant of whether a lineage can establish systemic infection. As a corollary, we hypothesize that borreliacidal action may differ among human subjects. To test these hypotheses, we isolated primary B. burgdorferi clones from field-collected ticks and determined whether the killing effects of human serum differed among those clones in vitro and/or whether these effects were consistent among human sera. Clones associated with human invasiveness did not show higher survival in human serum compared to noninvasive clones. These results indicate that differential complement-mediated killing of B. burgdorferi lineages is not a determinant of invasiveness in humans. Only one significant difference in the survivorship of individual clones incubated in different human sera was detected, suggesting that complement-mediated killing of B. burgdorferi is usually similar among humans. Mechanisms other than differential human complement-mediated killing of B. burgdorferi lineages likely explain why only certain lineages cause the majority of disseminated human infections

Social infrastructures for the post-Covid recovery in the UK

The central conflict facing policymakers, the voluntary sector, and communities during the Covid-19 pandemic has been keeping safe from a virus that is transmitted interpersonally while also providing vital support to those in need. The report presents the findings from 12 months of ethnographic, participatory, and quantitative research, which has revealed that people have fallen back on their families, neighbourhoods and communities in order to navigate new challenges and burden. We call these networks of kinship and care within and between families, friends, and communities “social infrastructures” and argue that economic life and pandemic recovery relies on the strength of these foundational relations. In the UK, local and rapid response initiatives saved lives as voluntary sector, religious organisations, and Community Champions built on these relations of care to encourage vaccine uptake. These innovative social projects also helped people to grieve and recover from losses of life and livelihoods. We argue that both short- and long-term investment in these integrated social infrastructures is crucial for the post-Covid recovery in the UK

A cross-sectional study of vascular risk factors in a rural South African population : data from the Southern African Stroke Prevention Initiative (SASPI)

Background: Rural sub-Saharan Africa is at an early stage of economic and health transition. It is predicted that the 21st century will see a serious added economic burden from non-communicable disease including vascular disease in low-income countries as they progress through the transition. The stage of vascular disease in a population is thought to result from the prevalence of vascular risk factors. Already hypertension and stroke are common in adults in sub-Saharan Africa. Using a multidisciplinary approach we aimed to assess the prevalence of several vascular risk factors in Agincourt, a rural demographic surveillance site in South Africa. Methods: We performed a cross sectional random sample survey of adults aged over 35 in Agincourt (population ≈ 70 000). Participants were visited at home by a trained nurse who administered a questionnaire, carried out clinical measurements and took a blood sample. From this we assessed participants' history of vascular risk, blood pressure using an OMRON 705 CP monitor, waist circumference, body mass index (BMI), ankle brachial index (ABI), and total and HDL cholesterol. Results: 402 people (24% men) participated. There was a high prevalence of smoking in men, but the number of cigarettes smoked was small. There was a striking difference in mean BMI between men and women (22.8 kg/m2 versus 27.2 kg/m2), but levels of blood pressure were very similar. 43% of participants had a blood pressure greater than 140/90 or were on anti-hypertensive treatment and 37% of participants identified with measured high blood pressure were on pharmacological treatment. 12% of participants had an ABI of < 0.9, sugesting the presence of sub-clinical atheroma. 25.6% of participants had a total cholesterol level > 5 mmol/l. Conclusion: We found a high prevalence of hypertension, obesity in women, and a suggestion of subclinical atheroma despite relatively favourable cholesterol levels in a rural South African population. South Africa is facing the challenge of an emerging epidemic of vascular disease. Research to establish the social determinates of these risk factors and interventions to reduce both individual and population risk are required

A right to care: the social foundations of recovery from Covid-19

This report presents key findings from a 6-month ethnographic study on the impact of the Covid-19 pandemic on disadvantaged households and communities across the UK conducted by anthropologists from the London School of Economics, and associates. This research involved in-depth interviews and multiple surveys with people across communities in the UK, with particular focus on a number of case studies of intersecting disadvantage. Crucially, our research has found that Government policy can improve adherence to restrictions and reduce the negative impacts of the pandemic on disadvantaged communities by placing central importance on communities, social networks and households to the economy and social life. This would be the most effective way to increase public trust and adherence to Covid-19 measures, because it would recognise the suffering that communities have experienced and would build policy on the basis of what is most important to people - the thriving of their families and communities

Recent advances in hedge funds' performance attribution:performance persistence and fundamental factors

We survey articles on hedge funds' performance persistence and fundamental factors from the mid-1990s to the present. For performance persistence, we present some pioneering studies that contradict previous findings that hedge funds' performance is a short term matter. We discuss recent innovative studies that examine the size, age, performance fees and other factors to give a 360° view of hedge funds' performance attribution. Small funds, younger funds and funds with high performance fees all outperform the opposite. Long lockup period funds tend to outperform short lockups and domiciled funds tend to outperform offshore funds. This is the first survey of recent innovative and challenging studies into hedge funds' performance attribution, and it should be particularly useful to investors trying to choose between hedge funds

Recent Applications of Acyclic (Diene)iron Complexes and (Dienyl)iron Cations in Organic Synthesis

Complexation of (tricarbonyl)iron to an acyclic diene serves to protect the ligand against oxidation, reduction, and cycloaddition reactions, whereas the steric bulk of this adjunct serves to direct the approaches of reagents to unsaturated groups attached to the diene onto the face opposite to iron. Furthermore, the Fe(CO)3 moiety can serve to stabilize carbocation centers adjacent to the diene (i.e. pentadienyl-iron cations). Recent applications of these reactivities to the synthesis of polyene-, cyclopropane-, cycloheptadiene-, and cyclohexenone-containing natural products or analogues are presented

Match-fixing: working towards an ethical framework

How does match-fixing, or other unfair manipulation of matches, that involves under-performance by players, or refereeing and umpiring that prevents fair competition, be thought of in ethical terms? In this article, I outline the different forms that match-fixing can take and seek to comprehend these disparate scenarios within Kantian, Hegelian and contractualist ethical frameworks. I tentatively suggest that, by developing an ethical opposition to match-fixing in sport, we can give much greater substance to popular phrases such as ‘respect for the game’, encompassing the value of sport itself and respect for other players, fans, sponsors and organisers. Arguing that match-fixing denies recognition to these ‘others’ demonstrates how fundamentally match-fixing ‘hollows out’ sport because a fixed match is of no worth: the whole value of the game has literally been evacuated