Automatic maintenance of category hierarchy

Category hierarchy is an abstraction mechanism for efficiently managing large-scale resources. In an open environment, a category hierarchy will inevitably become inappropriate for managing resources that constantly change with unpredictable pattern. An inappropriate category hierarchy will mislead the management of resources. The increasing dynamicity and scale of online resources increase the requirement of automatically maintaining category hierarchy. Previous studies about category hierarchy mainly focus on either the generation of category hierarchy or the classification of resources under a pre-defined category hierarchy. The automatic maintenance of category hierarchy has been neglected. Making abstraction among categories and measuring the similarity between categories are two basic behaviours to generate a category hierarchy. Humans are good at making abstraction but limited in ability to calculate the similarities between large-scale resources. Computing models are good at calculating the similarities between large-scale resources but limited in ability to make abstraction. To take both advantages of human view and computing ability, this paper proposes a two-phase approach to automatically maintaining category hierarchy within two scales by detecting the internal pattern change of categories. The global phase clusters resources to generate a reference category hierarchy and gets similarity between categories to detect inappropriate categories in the initial category hierarchy. The accuracy of the clustering approaches in generating category hierarchy determines the rationality of the global maintenance. The local phase detects topical changes and then adjusts inappropriate categories with three local operations. The global phase can quickly target inappropriate categories top-down and carry out cross-branch adjustment, which can also accelerate the local-phase adjustments. The local phase detects and adjusts the local-range inappropriate categories that are not adjusted in the global phase. By incorporating the two complementary phase adjustments, the approach can significantly improve the topical cohesion and accuracy of category hierarchy. A new measure is proposed for evaluating category hierarchy considering not only the balance of the hierarchical structure but also the accuracy of classification. Experiments show that the proposed approach is feasible and effective to adjust inappropriate category hierarchy. The proposed approach can be used to maintain the category hierarchy for managing various resources in dynamic application environment. It also provides an approach to specialize the current online category hierarchy to organize resources with more specific categories.

Dosimetric Evaluation of Metal Artefact Reduction using Metal Artefact Reduction (MAR) Algorithm and Dual-energy Computed Tomography (CT) Method

Purpose: Computed Tomography (CT) is one of the standard diagnostic imaging modalities for the evaluation of a patient’s medical condition. In comparison to other imaging modalities such as Magnetic Resonance Imaging (MRI), CT is a fast acquisition imaging device with higher spatial resolution and higher contrast-to-noise ratio (CNR) for bony structures. CT images are presented through a gray scale of independent values in Hounsfield units (HU). High HU-valued materials represent higher density. High density materials, such as metal, tend to erroneously increase the HU values around it due to reconstruction software limitations. This problem of increased HU values due to metal presence is referred to as metal artefacts. Hip prostheses, dental fillings, aneurysm clips, and spinal clips are a few examples of metal objects that are of clinical relevance. These implants create artefacts such as beam hardening and photon starvation that distort CT images and degrade image quality. This is of great significance because the distortions may cause improper evaluation of images and inaccurate dose calculation in the treatment planning system. Different algorithms are being developed to reduce these artefacts for better image quality for both diagnostic and therapeutic purposes. However, very limited information is available about the effect of artefact correction on dose calculation accuracy. This research study evaluates the dosimetric effect of metal artefact reduction algorithms on severe artefacts on CT images. This study uses Gemstone Spectral Imaging (GSI)-based MAR algorithm, projection-based Metal Artefact Reduction (MAR) algorithm, and the Dual-Energy method.

Materials and Methods: The Gemstone Spectral Imaging (GSI)-based and SMART Metal Artefact Reduction (MAR) algorithms are metal artefact reduction protocols embedded in two different CT scanner models by General Electric (GE), and the Dual-Energy Imaging Method was developed at Duke University. All three approaches were applied in this research for dosimetric evaluation on CT images with severe metal artefacts. The first part of the research used a water phantom with four iodine syringes. Two sets of plans, multi-arc plans and single-arc plans, using the Volumetric Modulated Arc therapy (VMAT) technique were designed to avoid or minimize influences from high-density objects. The second part of the research used projection-based MAR Algorithm and the Dual-Energy Method. Calculated Doses (Mean, Minimum, and Maximum Doses) to the planning treatment volume (PTV) were compared and homogeneity index (HI) calculated.

Results: (1) Without the GSI-based MAR application, a percent error between mean dose and the absolute dose ranging from 3.4-5.7% per fraction was observed. In contrast, the error was decreased to a range of 0.09-2.3% per fraction with the GSI-based MAR algorithm. There was a percent difference ranging from 1.7-4.2% per fraction between with and without using the GSI-based MAR algorithm. (2) A range of 0.1-3.2% difference was observed for the maximum dose values, 1.5-10.4% for minimum dose difference, and 1.4-1.7% difference on the mean doses. Homogeneity indexes (HI) ranging from 0.068-0.065 for dual-energy method and 0.063-0.141 with projection-based MAR algorithm were also calculated.

Conclusion: (1) Percent error without using the GSI-based MAR algorithm may deviate as high as 5.7%. This error invalidates the goal of Radiation Therapy to provide a more precise treatment. Thus, GSI-based MAR algorithm was desirable due to its better dose calculation accuracy. (2) Based on direct numerical observation, there was no apparent deviation between the mean doses of different techniques but deviation was evident on the maximum and minimum doses. The HI for the dual-energy method almost achieved the desirable null values. In conclusion, the Dual-Energy method gave better dose calculation accuracy to the planning treatment volume (PTV) for images with metal artefacts than with or without GE MAR Algorithm.

Fearonomics and the Role of Nigeria's Private Sector in the Nigerian Ebola Response

Background: Outbreaks of infectious diseases such as Ebola have dramatic economic impacts on affected nations due to significant direct costs and indirect costs, as well as increased expenditure by the government to meet the health and security crisis. Despite its dense population, Nigeria was able to contain the outbreak swiftly and was declared Ebola free on 13th October 2014. Although Nigeria’s Ebola containment success was multifaceted, the private sector played a key role in Nigeria’s fight against Ebola. An epidemic of a disease like Ebola, not only consumes health resources but also detrimentally disrupts trade and travel to impact both public and private sector resulting in the ‘fearonomic’ effect of the contagion. In this thesis, I have defined ‘fearonomics’ or the ‘fearonomic effects’ of a disease as the intangible and intangible economic effects of both informed and misinformed aversion behavior exhibited by individuals, organizations, or countries during an outbreak. During an infectious disease outbreak, there is a significant potential for public-private sector collaborations that can help offset some of the government’s cost of controlling the epidemic.

Objective: The main objective of this study is to understand the ‘fearonomics’ of Ebola in Nigeria and to evaluate the role of the key private sector stakeholders in Nigeria’s Ebola response.

Methods: This retrospective qualitative study was conducted in Nigeria and utilizes grounded theory to look across different economic sectors in Nigeria to understand the impact of Ebola on Nigeria’s private sector and how it dealt with the various challenges posed by the disease and its ‘fearonomic effects'.

Results: Due to swift containment of Ebola in Nigeria, the economic impact of the disease was limited especially in comparison to the other Ebola-infected countries such as Liberia, Sierra Leone, and Guinea. However, the 2014 Ebola outbreak had more than a just direct impact on the country’s economy and despite the swift containment, no economic sector was immune to the disease’s fearonomic impact. The potential scale of the fearonomic impact of a disease like Ebola was one of the key motivators for the private sector engagement in the Ebola response.

The private sector in Nigeria played an essential role in facilitating the country’s response to Ebola. The private sector not only provided in-cash donations but significant in-kind support to both the Federal and State governments during the outbreak. Swift establishment of an Ebola Emergency Operation Centre (EEOC) was essential to the country’s response and was greatly facilitated by the private sector, showcasing the crucial role of private sector in the initial phase of an outbreak. The private sector contributed to Nigeria’s fight against Ebola not only by donating material assets but by continuing operations and partaking in knowledge sharing and advocacy. Some sector such as the private health sector, telecom sector, financial sector, oil and gas sector played a unique role in orchestrating the Nigerian Ebola response and were among the first movers during the outbreak.

This paper utilizes the lessons from Nigeria’s containment of Ebola to highlight the potential of public-private partnerships in preparedness, response, and recovery during an outbreak.

Using GIS and Remote Sensing Technologies to Identify Environmental Variables of Malaria Vector Breeding Sites in Western Kenya

This study used Landsat 8 satellite imagery to identify environmental variables of households with malaria vector breeding sites in a malaria endemic rural district in Western Kenya. Understanding the influence of environmental variables on the distribution of malaria has been critical in the strengthening of malaria control programs. Using remote sensing and GIS technologies, this study performed a land classification, NDVI, Tasseled Cap Wetness Index, and derived land surface temperature values of the study area and examined the significance of each variable in predicting the probability of a household with a mosquito breeding site with and without larvae. The findings of this study revealed that households with any potential breeding sites were characterized by higher moisture, higher vegetation density (NDVI) and in urban areas or roads. The results of this study also confirmed that land surface temperature was significant in explaining the presence of active mosquito breeding sites (P< 0.000). The present study showed that freely available Landsat 8 imagery has limited use in deriving environmental characteristics of malaria vector habitats at the scale of the Bungoma East District in Western Kenya.

Experiences of Internalized and Enacted Stigma among Women with Obstetric Fistula in Tanzania

Background: Obstetric fistula is the development of a necrosis between the bladder and the vagina and/or the bladder and the rectum as a result of prolonged obstructed labor, resulting in urinary or fecal incontinence. In Tanzania surgical repair for obstetric fistula is provided freely by the government but it is estimated that there are over 25,000 women living with an untreated fistula. These women experience high degrees of psycho-social stresses exacerbated by the stigma surrounding their condition. There is a dire need to explore stigma within this population in order to better understand its impact, as stigma affects both treatment seeking behavior as well as long term recovery of those who access surgical repair.

Study Aims: This study aims to understand the experiences of stigma among women with obstetric fistulas by examining both internalized and enacted stigma, and by identifying pertinent correlates of internalized stigma.

Methods: This mixed-methods study utilized both quantitative and qualitative data collected in two related studies at a single hospital in Moshi, Tanzania. All study participants were women receiving surgical repair for an obstetric fistula. In the quantitative portion, cross-sectional survey data were collected from 52 patients. The primary outcome was fistula-related stigma, measured using an adaptation of the HASI-P stigma scale, which included constructs of both internalized and enacted stigma. In the qualitative portion, 45 patients participated in a semi-structured in-depth interview, which explored topics such as stressors caused by the fistula, coping mechanisms, and available support. The transcripts were analyzed using analytic memos and an iterative process of thematic coding using the framework of content analysis.

Results: Expressions of internalized stigma were common in the sample, with a median score of 2.1 on a scale of 0 – 3. Internalized was significantly correlated with negative religious coping, social participation, impact of incontinence and enacted stigma. Qualitative analysis was consistent and demonstrated widespread themes of shame and embarrassment. Experiences of enacted stigma were not as common (median score of 0), although some items, like those pertaining to mockery and blame, were endorsed by up to 25% of the study sample. Themes of anticipated stigma (isolation and non-disclosure due to the possibility of stigmatization) were also evident in the qualitative sample and may explain the low enacted stigma scores observed.

Conclusion: In this sample of women receiving surgical repair for an obstetric fistula, stigma was evident, with internalized stigma resulting in psychological impacts for patients. Experiences of both anticipated and enacted stigma were also observed. There is a need to explore interventions that would decrease stigma while also increasing support for these women, as stigma may be a barrier towards accessing surgical repair and reintegration following surgery.

Keywords: Tanzania, obstetric fistula, stigma, maternal health

Calcium/Calmodulin-Dependent Protein Kinase II Serves as a Biochemical Integrator of Calcium Signals for the Induction of Synaptic Plasticity

Repetitive Ca2+ transients in dendritic spines induce various forms of synaptic plasticity by transmitting information encoded in their frequency and amplitude. CaMKII plays a critical role in decoding these Ca2+ signals to initiate long-lasting synaptic plasticity. However, the properties of CaMKII that mediate Ca2+ decoding in spines remain elusive. Here, I measured CaMKII activity in spines using fast-framing two-photon fluorescence lifetime imaging. Following each repetitive Ca2+ elevations, CaMKII activity increased in a stepwise manner. This signal integration, at the time scale of seconds, critically depended on Thr286 phosphorylation. In the absence of Thr286 phosphorylation, only by increasing the frequency of repetitive Ca2+ elevations could high peak CaMKII activity or plasticity be induced. In addition, I measured the association between CaMKII and Ca2+/CaM during spine plasticity induction. Unlike CaMKII activity, association of Ca2+/CaM to CaMKII plateaued at the first Ca2+ elevation event. This result indicated that integration of Ca2+ signals was initiated by the binding of Ca2+/CaM and amplified by the subsequent increases in Thr286-phosphorylated form of CaMKII. Together, these findings demonstrate that CaMKII functions as a leaky integrator of repetitive Ca2+ signals during the induction of synaptic plasticity, and that Thr286 phosphorylation is critical for defining the frequencies of such integration.

The geographies of encounter: investigating the spatiality and construction of 'meaningful' encounters with difference through the experiences of international students at University College Cork, Ireland

The purpose of this research is to investigate how international students negotiate encounters with Irish students and construct ‘meaning’ from those encounters in the spaces of the university and city. As cities are increasingly characterised by a multiplexity of diversity, the issue of living with difference is becoming more and more pertinent. In the wake of escalating socio-spatial polarisation, inter-cultural tension, racism, and xenophobia, the geographies of encounter seek to untangle the interactions that occur in the quotidian activities and spaces of everyday life to determine whether such encounters might reduce prejudice, antipathy and indifference and establish common social bonds (Amin 2002; Valentine 2008). Thus far, the literature has investigated a number of sites of encounter; public space, the home, neighbourhoods, schools, sports clubs, public transport, cafes and libraries (Wilson 2011; Schuermans 2013; Hemming 2011; Neal and Vincent 2011; Mayblin, Valentine and Anderrson 2015; Laurier and Philo 2006; Valentine and Sadgrove 2013; Harris, Valentine and Piekut 2014; Fincher and Iveson 2008). While these spaces produce a range of outcomes, the literature remains frustrated by a lack of clarity of what constitutes a ‘meaningful’ encounter and how such encounters might be planned for. Drawing on survey and interview data with full-time international students at University College Cork, Ireland, this study contributes to understanding how encounters are shaped by the construction and reproduction of particular identities in particular spaces, imbuing spaces with uneven power frameworks that produce diverse outcomes. Rather than identifying a singular ‘meaningful’ outcome of encounter as a potential panacea to the issues of exclusion and oppression, the contention here is to recognise a range of outcomes that are created by individuals in a range of ways. To define one outcome of encounter as ‘meaningful’ is to overlook the scale of intensity of diverse interactions and the multiplicity of ways in which people learn to live with difference.

(Table S1) Trace element and isotopic compositions of anhydrites sampled in the Manus Basin, Papua New Guinea

Microchemical analyses of rare earth element (REE) concentrations and Sr and S isotope ratios of anhydrite are used to identify sub-seafloor processes governing the formation of hydrothermal fluids in the convergent margin Manus Basin, Papua New Guinea. Samples comprise drill-core vein anhydrite and seafloor massive anhydrite from the PACMANUS (Roman Ruins, Snowcap and Fenway) and SuSu Knolls (North Su) active hydrothermal fields. Chondrite-normalized REE patterns in anhydrite show remarkable heterogeneity on the scale of individual grains, different from the near uniform REEN patterns measured in anhydrite from mid-ocean ridge deposits. The REEN patterns in anhydrite are correlated with REE distributions measured in hydrothermal fluids venting at the seafloor at these vent fields and are interpreted to record episodes of hydrothermal fluid formation affected by magmatic volatile degassing. 87Sr/86Sr ratios vary dramatically within individual grains between that of contemporary seawater and that of endmember hydrothermal fluid. Anhydrite was precipitated from a highly variable mixture of the two. The intra-grain heterogeneity implies that anhydrite preserves periods of contrasting hydrothermal versus seawater dominant near-seafloor fluid circulation. Most sulfate d34S values of anhydrite cluster around that of contemporary seawater, consistent with anhydrite precipitating from hydrothermal fluid mixed with locally entrained seawater. Sulfate d34S isotope ratios in some anhydrites are, however, lighter than that of seawater, which are interpreted as recording a source of sulfate derived from magmatic SO2 degassed from underlying felsic magmas in the Manus Basin. The range of elemental and isotopic signatures observed in anhydrite records a range of sub-seafloor processes including high-temperature hydrothermal fluid circulation, varying extents of magmatic volatile degassing, seawater entrainment and fluid mixing. The chemical and isotopic heterogeneity recorded in anhydrite at the inter- and intra-grain scale captures the dynamics of hydrothermal fluid formation and sub-seafloor circulation that is highly variable both spatially and temporally on timescales over which hydrothermal deposits are formed. Microchemical analysis of hydrothermal minerals can provide information about the temporal history of submarine hydrothermal systems that are variable over time and cannot necessarily be inferred only from the study of vent fluids.

Geochemistry and geomicrobiology profiles of ferruginous sediment, Lake Towuti, Indonesia

Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through weathering and deliver abundant iron (oxy)hydroxides but very little sulfate to the lake and its sediment. To characterize the sediment biogeochemistry, we collected cores at three sites with increasing water depth and decreasing bottom water oxygen concentrations. Microbial cell densities were highest at the shallow site - a feature we attribute to the availability of labile organic matter and the higher abundance of electron acceptors due to oxic bottom water conditions. At the two other sites, OM degradation and reduction processes below the oxycline led to partial electron acceptor depletion. Genetic information preserved in the sediment as extracellular DNA provides information on aerobic and anaerobic heterotrophs related to Actinobacteria, Nitrospirae, Chloroflexi and Thermoplasmatales. These taxa apparently played a significant role in the degradation of sinking organic matter. However, extracellular DNA concentrations rapidly decrease with core depth. Despite very low sulfate concentrations, sulfate-reducing bacteria were present and viable in sediments at all three sites, as confirmed by measurement of potential sulfate reduction rates. Microbial community fingerprinting supported the presence of taxa related to Deltaproteobacteria and Firmicutes with demonstrated capacity for iron and sulfate reduction. Concomitantly, sequences of Ruminococcaceae, Clostridiales and Methanomicrobiales indicated potential for fermentative hydrogen and methane production. Such first insights into ferruginous sediments show that microbial populations perform successive metabolisms related to sulfur, iron and methane. In theory, iron reduction could reoxidize reduced sulfur compounds and desorb OM from iron minerals to allow remineralization to methane. Overall, we found that biogeochemical processes in the sediments can be linked to redox differences in the bottom waters of the three sites, like oxidant concentrations and the supply of labile OM. At the scale of the lacustrine record, our geomicrobiological study should provide a means to link the extant subsurface biosphere to past environments.

Unrecognized Exodus, Unaccepted Accountability : The Looming Shortage of Principals and Vice Principals in Ontario Public School Boards (Working Paper 24)

To the apparent surprise of policy makers at the provincial and school board levels, Ontario’s public schools are about to experience a massive exodus of principals and vice principals. This report, funded by a grant from the Ontario Principals’ Council, details the scale of the retirement wave currently hitting Ontario’s public school boards. Data collected from 946 practicing school administrators suggest that the retirement rates will be almost 20 per cent higher than provincial estimates. Anecdotal evidence suggests that the pool of qualified candidates for these positions is also shrinking. Already, fewer individuals are applying for each available vacancy. The study examines the major dissatisfiers in the current role of school principal as experienced by incumbents. Interviews were also conducted with 92 individuals identified as exceptional candidates for the principalship who had opted not to follow that career path in order to determine what factors they found most important in their decision making. The report concludes with recommendations for the province, school boards and principals' organizations.

Financial media, globalisation, and China’s economic integration: comparing narrative construction of the Economist and Caijing

In June 2015, legal frameworks of the Asian Infrastructural Investment Bank were signed by its 57 founding members. Proposed and initiated by China, this multilateral development bank is considered to be an Asian counterpart to break the monopoly of the World Bank and the International Monetary Fund. In October 2015, China’s Central Bank announced a benchmark interest rate cut to combat the economic slowdown. The easing policy coincides with the European Central Bank’s announcement of doubts over US Fed’s commitment to raise interest rates. Global stock markets responded positively to China’s move, with the exception of the indexes from Wall Street (Bland, 2015; Elliott, 2015). In the meantime, China’s ‘One Belt, One Road’ (or New Silk Road Economic Belt) became atopic of discourse in relation to its growing global economy, as China pledged $40 billion to trade and infrastructure projects (Bermingham, 2015). The foreign policy aims to reinforce the economic belt from western China through Central Asia towards Europe, as well as to construct maritime trading routes from coastal China through the South China Sea (Summers, 2015). In 2012, The Economist launched a new China section, to reveal the complexity of the‘meteoric rise’ of China. John Micklethwait, who was then the chief editor of the magazine, said that China’s emergence as a global power justified giving it a section of its own(Roush, 2012). In July 2015, Hu Shuli, the former chief editor of Caijing, announced the launch of a think tank and financial data service division called Caixin Insight Group, which encompasses the new Caixin China Purchasing Managers Index (PMI). Incooperation with with Markit Group, a principal global provider of PMI, the index soon became a widely cited economic indicator. One anecdote from November’s Caixin shows how much has changed: in a high-profile dialogue between Hu Shuli and Kevin Rudd, Hu insisted on asking questions in English; interestingly, the former Prime Minister of Australia insisted on replying in Chinese. These recent developments point to one thing: the economic ascent of China and its increasing influence on the power play between economics and politics in world markets. China has begun to take a more active role in rule making and enforcement under neoliberal frameworks. However, due to the country’s size and the scale of its economy in comparison to other countries, China’s version of globalisation has unique characteristics. The ‘Capitalist-socialist’ paradox is vital to China’s market-oriented transformation. In order to comprehend how such unique features are articulated and understood, there are several questions worth investigating in the realms of media and communication studies,such as how China’s neoliberal restructuring is portrayed and perceived by different types of interested parties, and how these portrayals are de-contextualised and re-contextualised in global or Anglo-American narratives. Therefore, based on a combination of the themes of globalisation, financial media and China’s economic integration, this thesis attempts to explore how financial media construct the narratives of China’s economic globalisation through the deployment of comparative and multi-disciplinary approaches. Two outstanding elite financial magazines, Britain’s The Economist, which has a global readership and influence, and Caijing, China’s leading financial magazine, are chosen as case studies to exemplify differing media discourses, representing, respectively, Anglo-American and Chinese socio-economic and political backgrounds, as well as their own journalistic cultures. This thesis tries to answer the questions of how and why China’s neoliberal restructuring is constructed from a globally-oriented perspective. The construction primarily involves people who are influential in business and policymaking. Hence, the analysis falls into the paradigm of elite-elite communication, which is an important but relatively less developed perspective in studying China and its globalisation. The comparing of characteristics of narrative construction are the result of the textual analysis of articles published over a ten-year period (mid-1998 to mid-2008). The corpus of samples come from the two media outlets’ coverage of three selected events:China becoming a member of the World Trade Organization, its outward direct investment, and the listing of stocks of Chinese companies in overseas exchanges, which are mutually exclusive in sample collection and collectively exhaustive in the inclusion of articles regarding China’s economic globalisation. The findings help to understand that, despite language, socio-economic and political differences, elite financial media with globally-oriented readerships share similar methods of and approaches to agenda setting, the evaluation of news prominence, the selection of frame, and the advocacy of deeply rooted neoliberal ideas. The comparison of their distinctive features reflects the different phases of building up the sense of identity in their readers as global elites, as well as the different economic interests that are aligned with the corresponding readerships. However, textual analysis is only relevant in terms of exploring how the narratives are constructed and the elements they include; textual analysis alone prevents us from seeing the obstacles and the constrains of the journalistic practices of construction. Therefore, this thesis provides a brief discussion of interviews with practitioners from the two media, in order to understand how similar or different narratives are manifested and perceived, how the concept of neoliberalism deviates from and is justified in the Chinese context, and how and for what purpose deviations arise from Western to Chinese contexts. The thesis also contributes to defining financial media in the domain of elite communication. The relevant and closely interlocking concepts of globalisation, elitism and neoliberalism are discussed, and are used as a theoretical bedrock in the analysis of texts and contexts. It is important to address the agenda-setting and ideological role of elite financial media, because of its narrative formula of infusing business facts with opinions,which is important in constructing the global elite identity as well as influencing neoliberal policy-making. On the other hand, ‘journalistic professionalism’ has been redefined, in that the elite identity is shared by the content producer, reader and the actors in the news stories emerging from the much-compressed news cycle. The professionalism of elite financial media requires a dual definition, that of being professional in the understanding of business facts and statistics, and that of being professional in the making sense of stories by deploying economic logic.

Default Invariance: Naïve Category of Law and Finance

Default invariance is the idea that default does not change at any scale of law and finance. Default is a conserved quantity in a universe where fundamental principles of law and finance operate. It exists at the micro-level as part of the fundamental structure of every financial transaction, and at the macro- level, as a fixed critical point within the relatively stable phases of the law and finance cycle. A key point is that default is equivalent to maximizing uncertainty at the micro-level and at the macro-level, is equivalent to the phase transition where unbearable fluctuations occur in all forms of risk transformation, including maturity, liquidity and credit. As such, default invariance is the glue that links the micro and macro structures of law and finance. In this essay, we apply naïve category theory (NCT), a type of mapping logic, to these types of phenomena. The purpose of using NCT is to introduce a rigorous (but simple) mathematical methodology to law and finance discourse and to show that these types of structural considerations are of prime practical importance and significance to law and finance practitioners. These mappings imply a number of novel areas of investigation. From the micro- structure, three macro-approximations are implied. These approximations form the core analytical framework which we will use to examine the phenomena and hypothesize rules governing law and finance. Our observations from these approximations are grouped into five findings. While the entirety of the five findings can be encapsulated by the three approximations, since the intended audience of this paper is the non-specialist in law, finance and category theory, for ease of access we will illustrate the use of the mappings with relatively common concepts drawn from law and finance, focusing especially on financial contracts, derivatives, Shadow Banking, credit rating agencies and credit crises.

Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study

Investigating the variability of Agulhas leakage, the volume transport of water from the Indian Ocean to the South Atlantic Ocean, is highly relevant due to its potential contribution to the Atlantic Meridional Overturning Circulation as well as the global circulation of heat and salt and hence global climate. Quantifying Agulhas leakage is challenging due to the non-linear nature of this process; current observations are insufficient to estimate its variability and ocean models all have biases in this region, even at high resolution . An Eulerian threshold integration method is developed to examine the mechanisms of Agulhas leakage variability in six ocean model simulations of varying resolution. This intercomparison, based on the circulation and thermo- haline structure at the Good Hope line, a transect to the south west of the southern tip of Africa, is used to identify features that are robust regardless of the model used and takes into account the thermohaline biases of each model. When determined by a passive tracer method, 60 % of the magnitude of Agulhas leakage is captured and more than 80 % of its temporal fluctuations, suggesting that the method is appropriate for investigating the variability of Agulhas leakage. In all simulations but one, the major driver of variability is associated with mesoscale features passing through the section. High resolution (<1/10 deg.) hindcast models agree on the temporal (2–4 cycles per year) and spatial (300–500 km) scales of these features corresponding to observed Agulhas Rings. Coarser resolution models (<1/4 deg.) reproduce similar time scale of variability of Agulhas leakage in spite of their difficulties in representing the Agulhas rings properties. A coarser resolution climate model (2 deg.) does not resolve the spatio-temporal mechanism of variability of Agulhas leakage. Hence it is expected to underestimate the contribution of Agulhas Current System to climate variability.

Spatio-temporal characteristics of Agulhas leakage: a model inter-comparison study

Investigating the variability of Agulhas leakage, the volume transport of water from the Indian Ocean to the South Atlantic Ocean, is highly relevant due to its potential contribution to the Atlantic Meridional Overturning Circulation as well as the global circulation of heat and salt and hence global climate. Quantifying Agulhas leakage is challenging due to the non-linear nature of this process; current observations are insufficient to estimate its variability and ocean models all have biases in this region, even at high resolution . An Eulerian threshold integration method is developed to examine the mechanisms of Agulhas leakage variability in six ocean model simulations of varying resolution. This intercomparison, based on the circulation and thermo- haline structure at the Good Hope line, a transect to the south west of the southern tip of Africa, is used to identify features that are robust regardless of the model used and takes into account the thermohaline biases of each model. When determined by a passive tracer method, 60 % of the magnitude of Agulhas leakage is captured and more than 80 % of its temporal fluctuations, suggesting that the method is appropriate for investigating the variability of Agulhas leakage. In all simulations but one, the major driver of variability is associated with mesoscale features passing through the section. High resolution (<1/10 deg.) hindcast models agree on the temporal (2–4 cycles per year) and spatial (300–500 km) scales of these features corresponding to observed Agulhas Rings. Coarser resolution models (<1/4 deg.) reproduce similar time scale of variability of Agulhas leakage in spite of their difficulties in representing the Agulhas rings properties. A coarser resolution climate model (2 deg.) does not resolve the spatio-temporal mechanism of variability of Agulhas leakage. Hence it is expected to underestimate the contribution of Agulhas Current System to climate variability.

The crowded magnetosphere of the post-common-envelope binary QS Virginis

We present high-speed photometry and high-resolution spectroscopy of the eclipsing post-common-envelope binary QS Virginis (QS Vir). Our Ultraviolet and Visual Echelle Spectrograph (UVES) spectra span multiple orbits over more than a year and reveal the presence of several large prominences passing in front of both the M star and its white dwarf companion, allowing us to triangulate their positions. Despite showing small variations on a time-scale of days, they persist for more than a year and may last decades. One large prominence extends almost three stellar radii from the M star. Roche tomography reveals that the M star is heavily spotted and that these spots are long-lived and in relatively fixed locations, preferentially found on the hemisphere facing the white dwarf. We also determine precise binary and physical parameters for the system. We find that the 14 220 ± 350 K white dwarf is relatively massive, 0.782 ± 0.013 M⊙, and has a radius of 0.010 68 ± 0.000 07 R⊙, consistent with evolutionary models. The tidally distorted M star has a mass of 0.382 ± 0.006 M⊙ and a radius of 0.381 ± 0.003 R⊙, also consistent with evolutionary models. We find that the magnesium absorption line from the white dwarf is broader than expected. This could be due to rotation (implying a spin period of only ˜700 s), or due to a weak (˜100 kG) magnetic field, we favour the latter interpretation. Since the M star's radius is still within its Roche lobe and there is no evidence that it is overinflated, we conclude that QS Vir is most likely a pre-cataclysmic binary just about to become semidetached.