University of Hull

About: University of Hull is a education organization based out in Hull, Kingston upon Hull, United Kingdom. It is known for research contribution in the topics: Population & Liquid crystal. The organization has 9546 authors who have published 22062 publications receiving 648925 citations.

The role of oxygen limitation in the formation of poly-β-hydroxybutyrate during batch and continuous culture of Azotobacter beijerinckii

Abstract: Azotobacter beijerinckii was grown in ammonia-free glucose–mineral salts media in batch culture and in chemostat cultures limited by the supply of glucose, oxygen or molecular nitrogen. In batch culture poly-β-hydroxybutyrate was formed towards the end of exponential growth and accumulated to about 74% of the cell dry weight. In chemostat cultures little poly-β-hydroxybutyrate accumulated in organisms that were nitrogen-limited, but when oxygen limited a much increased yield of cells per mol of glucose was observed, and the organisms contained up to 50% of their dry weight of poly-β-hydroxybutyrate. In carbon-limited cultures (D, the dilution rate,=0.035–0.240h−1), the growth yield ranged from 13.1 to 19.8g/mol of glucose and the poly-β-hydroxybutyrate content did not exceed 3.0% of the dry weight. In oxygen-limited cultures (D=0.049–0.252h−1) the growth yield ranged from 48.4 to 70.1g/mol of glucose and the poly-β-hydroxybutyrate content was between 19.6 and 44.6% of dry weight. In nitrogen-limited cultures (D=0.053–0.255h−1) the growth yield ranged from 7.45 to 19.9g/mol of glucose and the poly-β-hydroxybutyrate content was less than 1.5% of dry weight. The sudden imposition of oxygen limitation on a nitrogen-limited chemostat culture produced a rapid increase in poly-β-hydroxybutyrate content and cell yield. Determinations on chemostat cultures revealed that during oxygen-limited steady states (D=0.1h−1) the oxygen uptake decreased to 100μl h−1 per mg dry wt. compared with 675 for a glucose-limited culture (D=0.1h−1). Nitrogen-limited cultures had CO2 production values in situ ranging from 660 to 1055μl h−1 per mg dry wt. at growth rates of 0.053–0.234h−1 and carbon-limited cultures exhibited a variation of CO2 production between 185 and 1328μl h−1 per mg dry wt. at growth rates between 0.035 and 0.240h−1. These findings are discussed in relation to poly-β-hydroxybutyrate formation, growth efficiency and growth yield during growth on glucose. We suggest that poly-β-hydroxybutyrate is produced in response to oxygen limitation and represents not only a store of carbon and energy but also an electron sink into which excess of reducing power can be channelled.

Integrating the LISFLOOD-FP 2D hydrodynamic model with the CAESAR model: implications for modelling landscape evolution

Abstract: Landscape evolution models (LEMs) simulate the geomorphic development of river basins over long time periods and large space scales (100s–1000s of years, 100s of km2). Due to these scales they have been developed with simple steady flow models that enable long time steps (e.g. years) to be modelled, but not shorter term hydrodynamic effects (e.g. the passage of a flood wave). Nonsteady flow models that incorporate these hydrodynamic effects typically require far shorter time steps (seconds or less) and use more expensive numerical solutions hindering their inclusion in LEMs. The recently developed LISFLOOD-FP simplified 2D flow model addresses this issue by solving a reduced form of the shallow water equations using a very simple numerical scheme, thus generating a significant increase in computational efficiency over previous hydrodynamic methods. This leads to potential convergence of computational cost between LEMs and hydrodynamic models, and presents an opportunity to combine such schemes. This paper outlines how two such models (the LEM CAESAR and the hydrodynamic model LISFLOOD-FP) were merged to create the new CAESAR-Lisflood model, and through a series of preliminary tests shows that using a hydrodynamic model to route flow in an LEM affords many advantages. The new model is fast, computationally efficient and has a stronger physical basis than a previous version of the CAESAR model. For the first time it allows hydrodynamic effects (tidal flows, lake filling, alluvial fans blocking valley floor) to be represented in an LEM, as well as producing noticeably different results to steady flow models. This suggests that the simplification of using steady flow in existing LEMs may bias their findings significantly.

British Society of Gastroenterology guidance for management of inflammatory bowel disease during the COVID-19 pandemic.

Abstract: The COVID-19 pandemic is putting unprecedented pressures on healthcare systems globally. Early insights have been made possible by rapid sharing of data from China and Italy. In the UK, we have rapidly mobilised inflammatory bowel disease (IBD) centres in order that preparations can be made to protect our patients and the clinical services they rely on. This is a novel coronavirus; much is unknown as to how it will affect people with IBD. We also lack information about the impact of different immunosuppressive medications. To address this uncertainty, the British Society of Gastroenterology (BSG) COVID-19 IBD Working Group has used the best available data and expert opinion to generate a risk grid that groups patients into highest, moderate and lowest risk categories. This grid allows patients to be instructed to follow the UK government's advice for shielding, stringent and standard advice regarding social distancing, respectively. Further considerations are given to service provision, medical and surgical therapy, endoscopy, imaging and clinical trials.

Analog and mixed-signal benchmark circuits-first release

Abstract: The IEEE Mixed-Signal Technical Activity Committee is developing a common set of benchmark circuits for use in researching and evaluating analog fault modeling, test generation, design-for-test, and built-in self-test methodologies. The first release circuits are based on MITEL Semiconductor's 1.5 /spl mu/m and 1.2 /spl mu/m CMOS technologies and they will allow engineers and researchers working in analog and mixed-signal testing to compare test results as is done in the digital domain. This paper presents a set of typical circuits described by netlists in HSPICE format. Schematic diagrams, simulation results and measured results, if available, are provided together with layout and a typical test environment. The full details are available on the web page dedicated to analog and mixed-signal benchmarks.

In Defence of Paradigm Incommensurability

Abstract: This paper presents a rigorous defence of paradigm incommensurability as con ceptualized by Burrell and Morgan, arguing that it is a necessary defence against scientistic authoritarianism. Two recent attacks on paradigm incommensurability are examined which, although emerging from different intellectual traditions, are both seen to imply the restoration of the authority of scientism characteristic of the postmodernism of reaction. Both critiques base their attack on the work of Kuhn but this basis is rejected on the grounds, inter alia, of a clear absence of isomorphism between the paradigmatic model of Kuhn and that of Burrell and Morgan. Finally, the paper considers the relevance of paradigm incommensur ability in the context of non-reactive postmodernism.