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

Investigating the variability of the 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 (AMOC) and the global circulation of heat, salt and freshwater, hence to the global climate. As observations of the leakage are scattered in time and space, ocean model outputs are unavoidable to describe its mechanisms of variability. However, the Agulhas leakage is part of a system that still represents a challenge to modellers, because of its degree of non-linearity. As a consequence, this thesis reports the study of the mechanisms of variability of the Agulhas leakage in six ocean model outputs of varying resolution, vertical discretization and boundary conditions. Inter-comparing several model outputs allow one to identify which characteristics of variability are robust. It also provides valuable information on the model speci_cs required to correctly represent the mechanisms of variability of the Agulhas leakage and hence its contribution to climate variability. The Agulhas leakage is estimated at the Good Hope line, a section through the centre of the Cape Basin, using a Eulerian threshold integration method based on the thermo- haline properties of water masses along the line. The threshold method also takes into account the thermohaline biases of each model. Other methods have been tested but the former was selected because it yields an Agulhas Leakage that represents 60% of the actual magnitude as determined by a passive tracer method (only available in one simulation) and captures nearly all of the temporal variability

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

Investigating the variability of the 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 (AMOC) and the global circulation of heat, salt and freshwater, hence to the global climate. As observations of the leakage are scattered in time and space, ocean model outputs are unavoidable to describe its mechanisms of variability. However, the Agulhas leakage is part of a system that still represents a challenge to modellers, because of its degree of non-linearity. As a consequence, this thesis reports the study of the mechanisms of variability of the Agulhas leakage in six ocean model outputs of varying resolution, vertical discretization and boundary conditions. Inter-comparing several model outputs allow one to identify which characteristics of variability are robust. It also provides valuable information on the model speci_cs required to correctly represent the mechanisms of variability of the Agulhas leakage and hence its contribution to climate variability. The Agulhas leakage is estimated at the Good Hope line, a section through the centre of the Cape Basin, using a Eulerian threshold integration method based on the thermo- haline properties of water masses along the line. The threshold method also takes into account the thermohaline biases of each model. Other methods have been tested but the former was selected because it yields an Agulhas Leakage that represents 60% of the actual magnitude as determined by a passive tracer method (only available in one simulation) and captures nearly all of the temporal variability

Implementing the Innovative On Tour STEAM Art Integration Curriculum Program in a Georgia Title l School with Amazing Results!

How did a Title l school located in a designated rural Georgia school district implement a Pilot On Tour STEAM Art Integration Curriculum Program to promote a balanced curriculum for Title I students? Findings and leadership practices from this study will be shared and presenters will be available during and after the conference along with supporting handouts

A Reply to My Critics: The Critical Spirit of Bourdieusian Language

Drawing on my article “Bourdieusian reflections on language: Unavoidable conditions of the real speech situation”, this paper provides a detailed response to the above commentaries by Lisa Adkins, Bridget Fowler, Michael Grenfell, David Inglis, Hans-Herbert Kögler, Steph Lawler, William Outhwaite, Derek Robbins and Bryan S. Turner. The main purpose of this “Reply to my critics” is to reflect upon the most important issues raised by these commentators and thereby contribute to a more nuanced understanding of key questions arising from Bourdieu’s analysis of language

The Antilles Current and wind-driven gyre circulation at 26oN

The Antilles Current is a narrow, northward flowing boundary current in the western Atlantic just east of the Bahamas. Its role in the larger scale circulation has been debated: alternately thought to be part of the western boundary closure of the gyre circulation or the northward flowing limb of the meridional overturning circulation (MOC). From 19 years of moored current meter observations (1987--1991, 2004--2018), we define the strength of the Antilles Current by the net transport between the Bahamas and 76.5°W (spanning about 45 km zonally) and in the thermocline (0–1000 m). We find a mean northward transport of 3.5 Sv, substantial interannual variability, and no discernable trend since 1987. The interannual variability of the AC transport is independent of the variability of the Florida Current (the Gulf Stream through the Florida Straits). Instead, the Antilles Current contributes to the interannual variability of the MOC at 26°N, while the trend in the strength of the gyre circulation (defined as the transbasin thermocline transport minus the AC) is responsible for the trend in the MOC. In particular, the 2009/10 slowdown of the MOC resulted from a weaker northward AC transport, rather than an intensified gyre transport. Using the recent 14 years of in situ transport records, we compare the interannual variability of the gyre circulation to that of wind stress curl forcing via a Sverdrup transport calculation, identifying a potential role for wind stress curl (WSC) forcing at 26°N with a ~2 year lag until 2016. From 2016, the predicted gyre circulation using WSC diverges from the measured gyre strength

A GH81-type β-glucan-binding protein facilitates colonization by mutualistic fungi in barley

Cell walls are important interfaces of plant-fungal interactions. Host cell walls act as robust physical and chemical barriers against fungal invaders, making them an essential line of defense. Upon fungal colonization, plants deposit phenolics and callose at the sites of fungal penetration to reinforce their walls and prevent further fungal progression. Alterations in the composition of plant cell walls significantly impact host susceptibility. Furthermore, plants and fungi secrete glycan hydrolases acting on each other's cell walls. These enzymes release a wide range of sugar oligomers into the apoplast, some of which trigger the activation of host immunity via host surface receptors. Recent characterization of cell walls from plant-colonizing fungi have emphasized the abundance of β-glucans in different cell wall layers, which makes them suitable targets for recognition. To characterize host components involved in immunity against fungi, we performed a protein pull-down with the biotinylated β-glucan laminarin. Thereby, we identified a glycoside hydrolase family 81-type glucan-binding protein (GBP) as the major β-glucan interactor. Mutation of GBP1 and its only paralogue GBP2 in barley led to decreased colonization by the beneficial root endophytes Serendipita indica and S. vermifera, as well as the arbuscular mycorrhizal fungus Rhizophagus irregularis. The reduction of symbiotic colonization was accompanied by enhanced responses at the host cell wall. Moreover, GBP mutation in barley also increased resistance to fungal infections in roots and leaves by the hemibiotrophic pathogen Bipolaris sorokiniana and the obligate biotrophic pathogen Blumeria graminis f. sp. hordei, respectively. These results indicate that GBP1 is involved in the establishment of symbiotic associations with beneficial fungi, a role that has potentially been appropriated by barley-adapted pathogens

A human domain antibody and Lewisb glycoconjugate that inhibit binding of helicobacter pylori to Lewisb receptor and adhesion to human gastric epithelium

Increasing antibiotic resistance has prompted development of alternative approaches to antimicrobial therapy, including blocking microbial adhesion to host receptors. The BabA adhesin of Helicobacter pylori binds to fucosylated blood group antigens, such as the Lewisb antigens in human primate gastric mucosa. We have isolated a human domain antibody specific for BabA that inhibits binding of BabA to Lewisb and prevents adhesion of H. pylori to human gastric epithelium. In addition, Lewisb oligosaccharides covalently linked to poly‐d‐lysine inhibited BabA binding to Leb. The poly‐d‐lysine‐Leb hexasaccharide and an Leb human serum albumin conjugate not only inhibited adherence of H. pylori to gastric epithelium but also displaced adherent bacteria when added to human stomach sections. Combinations of Leb and sialyl Lex or domain antibody 25 and sialyl Lex acted synergistically. Domain antibody 25 inhibitor may have potential for prophylactic use and, in combination with Leb glycoconjugates, therapeutic use in treatment of drug‐resistant H. pylori infection