Centralizers of the infinite symmetric group

We review and introduce several approaches to the study of centralizer algebras of the infinite symmetric group $S_\infty$. Our study is led by the double commutant relationships between finite symmetric groups and partition algebras; each approach produces a centralizer algebra that is contained in a partition algebra. Our goal is to incorporate invariants of $S_\infty$, which ties our work to the study of symmetric functions in non-commuting variables. We resultantly explore sequence spaces as permutation modules, which yields families of non-unitary representations of $S_\infty$

PUTATIVE ROLES OF CD200 IN THE LEUKEMOGENESIS AND IMMUNE EVASION OF LEUKEMIA STEM CELLS

Acute myeloid leukemia (AML) stem cells (LSC) are capable of surviving current standard chemotherapy and are the likely source of deadly, relapsed disease. While stem cell transplant serves as proof-of-principle that AML LSCs can be eliminated by the immune system, the translation of existing immunotherapies to AML have been met with limited success. Consequently, understanding and exploiting the unique immune mechanisms of AML LSCs is critical. To identify novel immunotherapeutic targets, we sourced multiple large, publicly available datasets and identified CD200 as a potential stem-cell specific immune checkpoint in AML. We hypothesized that CD200 was a stem-cell specific mechanism of evading immune detection and destruction and that anti-CD200 antibody therapy could effectively eliminate AML LSCs by engaging the patient’s immune system. To study the functional role of CD200 in AML, we established and characterized two isogenic cell line models of CD200 expression. Utilizing these cells, we investigated the effects of CD200+ leukemia on the effector functions of isolated T cells, NK cells, and macrophages in vitro. To study CD200 in a physiological setting, we established a PBMC-humanized mouse model, in which we could characterize progression of CD200+ and CD200- AML in the presence of an activate human immune response. Further, we used this model to compare the effects of CD200+ AML on the transcriptional activity and functional capacity of the human T cells. To therapeutically target CD200+ leukemia, we developed a novel, humanized CD200-IgG1 antibody. We investigated the potential of this antibody to both inhibit the immunosuppressive signaling through the CD200 receptor and initiate an antibody-mediated response. By comparing the therapeutic efficacy in both immunocompromised and PBMC-humanized mice, we confirmed that CD200-IgG1 could effectively eliminate CD200+ AML only in the presence of T cell-mediated response. Taken together, we conclude that CD200 is a marker of functional AML stem cells that aids in the escape of immune detection and destruction. Furthermore, these studies lay the groundwork for CD200-targeted therapeutic strategies to specifically eliminate LSCs and prevent relapse of AML

SO208 PLUMEFLUX: Ausbreitung von Galápagosplumematerial im äquatorialem Ostpazifik

The main objective of this Dissertation is the investigation of the distribution of Galápagos plume material in the equatorial East Pacific. It provides a more detailed view on the Galápagos plume and the adjacent Galápagos Spreading Center (GSC; also known as Cocos-Nazca-Spreading Center (CNS)) and contributes to further our understanding of plume-ridge interaction and mantle material transport within the earth upper mantle. Of special interest in this context is the far-field lateral transport of plume material (subproject 1) and the temporal evolution of plume-ridge interaction at the Galápagos plume-Galápagos Spreading Center system (sub-project 2). The necessary sample material in order to address these questions was recovered during the cruise SO208 with the German research vessel R/V Sonne in July/August 2010.Gegenstand der vorliegenden Dissertation ist die Untersuchung der Verbreitung von Galápagosplumematerial im äquatorialen Ostpazifik. Am Beispiel des Galápagosplume in Verbindung mit dem benachbarten Galápagosspreizungzentrum (GSC; auch als Cocos-Nazca-Spreizungszentrum (CNS) bezeichnet) soll diese Arbeit zu einem besseren Verständnis von Plume-Rücken-Wechselwirkungen und Materialtransport im oberen Mantel beitragen. Der Schwerpunkt wurde dabei auf die räumliche Ausdehnung von Galápagosplumematerial im äquatorialen Ostpazifik (Teilprojekt 1) und die zeitliche Entwicklung des Galápagosplume-Galápagosspreizungszentrum-Systems (Teilprojekt 2) gelegt. Die dafür analysierten Proben wurden während der Forschungsfahrt SO208 mit dem deutschen Forschungsschiff Sonne im Juli/August 2010 gewonnen

Temporal variations in Galápagos plume-ridge interaction at the Cocos-Nazca spreading center

The major goals of cruise SO208 with the German research vessel Sonne were to investigate 1) plume-ridge interaction through time at the Cocos-Nazca spreading center (CNS) north of the Galápagos Islands by sampling across axis profiles of the seafloor and 2) off axis volcanism at the East Pacific Rise (EPR) versus far field effects of the Galápagos hotspot documented in seamounts off the coast of N Costa Rica and Nicaragua. Overall the nature of material transfer from the plume to the ridge and its large scale distribution throughout the Eastern Pacific is being investigated by means of major and trace element and Sr-Nd-Pb (double spike) isotope data. The seamounts on the EPR generated part of the Cocos plate appear to originate on one hand from a depleted MORBlike source consistent with their formation near the EPR axis, while other seamounts formed through lower degrees melting of an enriched OIB source either more distant from the EPR or by intraplate volcanism. Geochemical profiles across the Western and Eastern CNS indicate the participation of two different Galápagos plume components with a change in the amount this material entering the CNS with time. While at the western profile element ratios of more to less incompatible elements show an overall decrease of a plume component, Wolf-Darwin or Northern domain [1], with increasing age, the opposite is observed at the eastern profile. The Central domain component [1] increases with increasing age of the crust in this area. These observations indicate variable flux of specific Galápagos plume components to the CNS over the past 800 000 years. Sr-Nd-Pb isotope data to verify these observations are currently being generated and will be presented at the conference. [1] Hoernle et al. (2000) Geology 28, 435–43