6,403 research outputs found
UMSL Bulletin 2023-2024
The 2023-2024 Bulletin and Course Catalog for the University of Missouri St. Louis.https://irl.umsl.edu/bulletin/1088/thumbnail.jp
Science and Innovations for Food Systems Transformation
This Open Access book compiles the findings of the Scientific Group of the United Nations Food Systems Summit 2021 and its research partners. The Scientific Group was an independent group of 28 food systems scientists from all over the world with a mandate from the Deputy Secretary-General of the United Nations. The chapters provide science- and research-based, state-of-the-art, solution-oriented knowledge and evidence to inform the transformation of contemporary food systems in order to achieve more sustainable, equitable and resilient systems
Improving low latency applications for reconfigurable devices
This thesis seeks to improve low latency application performance via architectural improvements in reconfigurable devices. This is achieved by improving resource utilisation and access, and by exploiting the different environments within which reconfigurable devices are deployed.
Our first contribution leverages devices deployed at the network level to enable the low latency processing of financial market data feeds. Financial exchanges transmit messages via two identical data feeds to reduce the chance of message loss. We present an approach to arbitrate these redundant feeds at the network level using a Field-Programmable Gate Array (FPGA). With support for any messaging protocol, we evaluate our design using the NASDAQ TotalView-ITCH, OPRA, and ARCA data feed protocols, and provide two simultaneous outputs: one prioritising low latency, and one prioritising high reliability with three dynamically configurable windowing methods.
Our second contribution is a new ring-based architecture for low latency, parallel access to FPGA memory. Traditional FPGA memory is formed by grouping block memories (BRAMs) together and accessing them as a single device. Our architecture accesses these BRAMs independently and in parallel. Targeting memory-based computing, which stores pre-computed function results in memory, we benefit low latency applications that rely on: highly-complex functions; iterative computation; or many parallel accesses to a shared resource. We assess square root, power, trigonometric, and hyperbolic functions within the FPGA, and provide a tool to convert Python functions to our new architecture.
Our third contribution extends the ring-based architecture to support any FPGA processing element. We unify E heterogeneous processing elements within compute pools, with each element implementing the same function, and the pool serving D parallel function calls. Our implementation-agnostic approach supports processing elements with different latencies, implementations, and pipeline lengths, as well as non-deterministic latencies. Compute pools evenly balance access to processing elements across the entire application, and are evaluated by implementing eight different neural network activation functions within an FPGA.Open Acces
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A review of natural language processing in contact centre automation
Contact centres have been highly valued by organizations for a long time. However, the COVID-19 pandemic has highlighted their critical importance in ensuring business continuity, economic activity, and quality customer support. The pandemic has led to an increase in customer inquiries related to payment extensions, cancellations, and stock inquiries, each with varying degrees of urgency. To address this challenge, organizations have taken the opportunity to re-evaluate the function of contact centres and explore innovative solutions. Next-generation platforms that incorporate machine learning techniques and natural language processing, such as self-service voice portals and chatbots, are being implemented to enhance customer service. These platforms offer robust features that equip customer agents with the necessary tools to provide exceptional customer support. Through an extensive review of existing literature, this paper aims to uncover research gaps and explore the advantages of transitioning to a contact centre that utilizes natural language solutions as the norm. Additionally, we will examine the major challenges faced by contact centre organizations and offer reco
Contribution of Pseudo-Focused Soft Protons to the Background of Athena
This PhD thesis explores the role of low energy protons, the so-called ‘soft protons', as a component of the background in view of the future ESA's X-ray mission Athena. As a matter of fact, a high level of soft proton flux at the focal plane of Athena can adversely affect the scientific goals of the mission. To prevent this, a correct estimate of the soft proton flux expected at the focal plane of the satellite is fundamental. Such an estimate can be achieved only if the reflectivity of soft protons from the optics is well understood, with efforts on both the experimental and the theoretical sides. To this aim, I applied the model of reflectivity of particles at grazing incidence proposed by Remizovich et al. (1980), under the non-elastic approximation, to the experimental measurements of proton scattering at low incident angles from XMM-Newton and eROSITA mirror samples. The mismatch between the model and the experimental data led me to create a new analytical semi-empirical model, where the parameter sigma enclosing the micro-physics of the interaction between the protons and the mirror lattice is directly derived by fitting the data. This new model gives a more accurate estimate of the scattering efficiency and energy loss distributions, but depends on the specific materials eROSITA and XMM-Newton are made of. For the model to be applied to Athena, new experimental data on Athena's optics, the Silicon Pore Optics (SPO), are necessary. These new data were acquired during dedicated experimental campaigns carried out by the Institut fur Astronomie und Astrophysik of the University of Tuebingen. The experiment consisted in measuring the scattering of low energy protons at grazing incidence from an Athena SPO sample, at two different incident energies, ~470 keV and ~170 keV, and at four different incident angles, 0.6 deg, 0.8 deg, 1.0 deg, and 1.2 deg. The new data are consistent, within the error bars, with the data from the eROSITA mirror sample, so that the same model can be used to estimate the scattering efficiency of SPO. A more accurate model can be built from a fit of the new data sets, provided that energy loss measurements are retrieved from the raw data. The new semi-empirical model can be implemented in a ray-tracing code to build a specific response matrix for protons. The construction of a proton response matrix is a 2-years project that falls within the AHEAD2020 activities, in view of the launch of Athena. The project foresees the construction of a proton response matrix for XMM-Newton as a reliable tool for the deconvolution of observed soft protons spectra. If the validation of this response matrix is successful, then the same procedure can be used to produce an analogous proton response matrix for Athena. In this framework, I performed a Geant4 simulation of the interaction of soft protons with the focal plane of XMM-Newton, consisting in a detailed representation of the 7 CCDs of the MOS camera, the filters, and the proton shields surrounding the focal plane assembly. The coupling of the Geant4 simulation with the output of the aforementioned ray-tracing will bring to the proton response matrix for XMM-Newton.
To reach a round research profile, I also analysed observational X-ray data from two binary X-ray sources, which represent ideal cases to test to what extent soft protons can affect the quality of observational data. The low level of background required for Athena will improve the knowledge we have of these systems and will enhance advanced studies for a wider sample of X-ray binaries. The first source is a very-faint millisecond pulsar in the globular cluster M22, for which I conducted a multi-wavelength search for counterparts. The lack of any optical counterpart returned an upper limit on the mass of the companion, allowing for a classification of the system as a so-called black widow binary, i.e., a low-mass X-ray binary with a companion star of mass M << 0.1 Msun. The analysis of the X-ray spectra favoured an intra-binary shock scenario as mechanism responsible for the X-ray emission. The second source is the well-known high-mass X-ray binary Vela X-1, for which I performed a high-resolution spectroscopy study of a Chandra/HETGS archival data, taken when the line of sight is intersecting the photoionisation wake. Standard plasma diagnostic techniques and simulations with the photoionisation codes CLOUDY and PION (in SPEX) suggested the presence of a multi-component plasma, which is typical for high-mass X-ray binaries with clumpy winds
System-wide stress testing & systemic risk
The financial crisis of 2007-2009, which brought the entire system at the brink of collapse, renewed efforts to guard against financial instability. A key pillar of the post-crisis regulatory toolkit is "stress testing". Stress tests provide a forward-looking examination of firms’ potential losses during severely ad- verse conditions. And enable timely action to recapitalise those firms who experience capital shortfalls in such crisis scenarios. Today’s regulatory stress tests do not heed the key lesson of the financial crisis: amplifications in the networked financial system must be taken into account to be able to assess systemic risk. Because of this, these tests are unable to assess systemic risk and ergo to address it – defeating their raison d’ˆetre.
The overarching research question in this thesis is whether new building blocks – expressing the heterogeneity of institutions, contracts, markets, constraints and behaviour in the interconnected financial system – can be supplied for system-wide stress tests to better capture the endogenous amplification of shocks in order to improve the assessment of systemic risk and the evaluation of prudential policies to address financial fragility.
The cornerstone of my thesis is the development of a generic network-based method, comprised of these five building blocks (i.e. institutions, contracts, markets, constraints and behaviour), for system-wide stress testing – which has gained traction from leading central banks, including the Bank of England and the European Central Bank. Using this method, I implement two data-driven models to address some of the most salient financial stability questions of today. First, we ask how the regulatory buffer size and its usability under Basel III affect systemic risk? We find that financial resilience decreases if regulatory buffers are seen to be less usable by banks. If regulatory buffers are not treated as usable, then regulatory buffers de facto act as capital requirements. In such case, if an adverse shock threatens an institution to breach its capital buffers constraints, it is forced to delever, which tends to have a destabilising effect on the financial markets. We show that the size of usable regulatory buffers that is required to maintain stability is underestimated if the interaction between exposure loss contagion, funding contagion, overlapping portfolio contagion and margin call contagion is not taken into account. Second, we inquire what the systemic implications are of the bail-in design to resolve systemically important banks? First of all, we find that the bail-in design tremendously matters for whether bail-ins can be credibly executed in system-wide financial crises and cases of large systemically impor- tant bank failures, without significantly exacerbating financial distress. Our results demonstrate that an early bail-in, strong recapitalisation and fair distribution of equity compensation by means of debt-to-equity conversion rates makes bail-in a feasible option on the table for idiosyncratic cases of bank failure and limits – but not eliminates – contagion in cases of system-wide distress. We further show that excluding run-prone, short-term debt from the application of the bail-in tool, increasing the requirements on loss absorbing debt and providing investors with certainty about the bail-in design lowers contagion in system-wide crises to manageable levels. Our findings highlight that while well-designed bail-ins could be credibly administered in system-wide crises, it is not clear that the current bail-in design is in the regime of stability. Altogether, the methods and findings of this thesis emphasise the promise that system-wide stress tests hold for regulators to efficaciously assess systemic risk and calibrate prudential policies constituting the financial architecture
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