Southern Annular Mode response to volcanic eruptions: implications for ice core proxies

Large tropical volcanic eruptions have been observed to have a significant influence on the large-scale circulation patterns of the Northern Hemisphere, through mechanisms related to the radiative effects of the sulfate aerosols resulting from the volcanic injection of sulfur dioxide into the stratosphere. While no such volcanically induced anomalies in Southern Hemisphere circulation have yet been observed, we find that in general circulation model simulations, eruptions with sulfur dioxide injections larger than that of the 1991 Mt. Pinatubo eruption do result in significant circulation changes in the SH, specifically an enhanced positive phase of the Southern Annular Mode (SAM). We explore the mechanisms for such a SAM response, as well as the corresponding changes in SH temperature, sea ice and precipitation. We also explore how the anomalously strong zonal winds characteristic of the positive SAM regime affect the rate of sulfate deposition to the Antarctic ice-sheet. We suggest that the use of ice-core sulfate records as a proxy for past volcanic activity may benefit from including knowledge of, or better assumptions regarding the changes in large scale atmospheric circulation after large tropical eruptions

Functional dissection of translocon proteins of the Salmonella Pathogenicity Island 2-encoded type III secretion system

<p>Abstract</p> <p>Background</p> <p>Type III secretion systems (T3SS) are essential virulence factors of most Gram-negative bacterial pathogens. T3SS deliver effector proteins directly into the cytoplasm of eukaryotic target cells and for this function, the insertion of a subset of T3SS proteins into the target cell membrane is important. These proteins form hetero-oligomeric pores acting as translocon for the delivery of effector proteins. <it>Salmonella enterica </it>is a facultative intracellular pathogen that uses the <it>Salmonella </it>Pathogenicity Island 2 (SPI2)-encoded T3SS to manipulate host cells in order to survive and proliferate within the <it>Salmonella</it>-containing vacuole of host cells. Previous work showed that SPI2-encoded SseB, SseC and SseD act to form the translocon of the SPI2-T3SS.</p> <p>Results</p> <p>Here we investigated the structural requirements of SseB and SseD to form a functional translocon. Based on bioinformatic predictions, deletional analyses of SseB and SseD were performed and the effect on secretion by the T3SS, formation of a translocon, translocation of effector proteins and intracellular replication was investigated. Our data showed that both SseB and SseD are very sensitive towards alterations of the primary structure of the proteins. Although proteins encoded by mutant alleles were still secreted, we observed that all mutations resulted in a loss of function of the SPI2-T3SS.</p> <p>Conclusion</p> <p>These observations indicate that translocon proteins of the SPI2-T3SS are highly evolved towards the formation of multi-subunit complex in the host cell membrane. Structural alterations are not tolerated and abrogate translocon function.</p

The University Münster model surgery system for Orthognathic surgery. Part I – The idea behind

Background: We describe a procedure for diagnosis and planning for orthognatic surgery based on international standards. A special 2D planning based on lateral cephalograms (Axis Orbital Marker Lines System) realize a transmission to the SAM 2P articulator (3D) by means of the Axis Orbital Plane. Methods: Former intraoperative measurement of the average height of the LeFort I osteotomy plane relative to the molar occlusal plane allow to construct a virtual osteotomy plane in the lateral cephalogram. This is the basis for the development of the Axis Orbital Marker Lines System (AO-MLS). Results: The AO-MLS is presented graphically, and in detail, with construction guidelines. The system could be integrated into various lateral cephalometric analysis- and surgical prediction schemes. It forms the basis for a standardized transfer of the 2D planning to the 3D planning in the articulator, and vice versa. This procedure makes it possible to generate surgical planning protocols based on the model surgery, which represent the dislocations in the proximity of the real osteotomy planes. Conclusions: The Axis Orbital Marker Lines System (software component) in conjunction with the University Münster Model Surgery System (hardware system) increases the predictability of model operations in orthognathic surgery

Validity of Landauer's principle in the quantum regime

We demonstrate the validity of Landauer's erasure principle in the strong coupling quantum regime by treating the system-reservoir interaction in a consistent way. We show that the initial coupling to the reservoir modifies both energy and entropy of the system and provide explicit expressions for the latter in the case of a damped quantum harmonic oscillator. These contributions are related to the Hamiltonian of mean force and dominate in the strong damping limit. They need therefore to be fully taken into account in any low-temperature thermodynamic analysis of quantum systems.Comment: 4 pages, 2 figure

Nonsteroidal Anti-Inflammatory Drugs and Ectodomain Shedding of the Amyloid Precursor Protein

Background: Epidemiological studies have suggested that long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced incidence of Alzheimer's disease (AD). Several mechanisms have been proposed to explain these findings including increased shedding of the soluble ectodomain of the amyloid precursor protein (sAPP), which functions as a neurotrophic and neuroprotective factor in vitro and in vivo. Objective: To clarify whether NSAIDs consistently stimulate sAPP secretion. Methods: 293-EBNA cells with stable overexpression of an APP-alkaline phosphatase fusion protein (APP-AP), SH-SY5Y and PC12 cells or primary telencephalic chicken neurons were treated with ibuprofen or indomethacin. APP shedding was then determined by measuring AP activity in conditioned media, Western blot analysis with antibodies against total sAPP or specific for sAPP-alpha, or in a pulse-chase paradigm. Results: AP activity in conditioned media was not increased after NSAID treatment of 293-EBNA cells whereas it was elevated by phorbol ester. Surprisingly, ibuprofen or indomethacin treatment of SH-SY5Y and PC12 cells expressing endogenous APP did not cause changes in sAPP or sAPP-alpha secretion or downregulation of cellular APP. These findings were further corroborated in primary chicken neuronal cultures. Conclusions: Using various experimental settings, we were unable to confirm sAPP or sAPP-alpha stimulation with the NSAIDs ibuprofen and indomethacin in transfected and nontransfected cells of neuronal and nonneuronal origin. Importantly, these findings seem to rule out chronic sAPP stimulation as an alternative mechanism of NSAID action in AD. Copyright (C) 2008 S. Karger AG, Base

High variability of plasmid uptake rates in Escherichia coli isolated from sewage and river sediments

The horizontal transfer of plasmids is a key mechanism behind the spread of antibiotic resistance in bacteria. So far, transfer rate constants were measured for a variety of plasmids, donors and recipients. The employed strains typically had a long history in laboratories. Existing data are, therefore, not necessarily representative for real-world environments. Moreover, information on the inter-strain variability of plasmid transfer rates is scarce. Using a high-throughput approach, we studied the uptake of RP4 by various Escherichia coli recipients using Serratia marcescens as the donor. The recipient strains were isolated from human-borne sewage and river sediments. The rate constants of plasmid transfer generally followed a log-normal distribution with considerable variance. The rate constants for good and poor recipients (95 and 5% quantile) differed by more than three orders of magnitude. Specifically, the inter-strain variability of the rate constant was large in comparison to alterations induced by low-level antibiotic exposure. We did not find evidence for diverging efficiencies of plasmid uptake between E. coli recipients of different origin. On average, strains isolated from river bottom sediments were equally efficient in the acquisition of RP4 as isolates extracted from sewage. We conclude that E. coli strains persisting in the aquatic environment and those of direct human origin share a similar intrinsic potential for the conjugative uptake of certain plasmids. In view of the large inter-strain variability, we propose to work towards probabilistic modeling of the environmental spread of antibiotic resistance.Peer reviewe

Altered processing of food stimuli in adolescents with loss of control eating

Loss of control eating (LOC) constitutes a common eating pathology in childhood and adolescence. Models developed for adult patients stress a biased processing of food-related stimuli as an important maintaining factor. To our knowledge, however, no EEG study to date investigated the processing of visual food stimuli in children or adolescents with LOC. Adolescents with at least one self-reported episode of LOC in the last four weeks and a matched control group completed a modified Go/NoGo task, with a numerical target or non-target stimulus being presented on one side of the screen and an irrelevant high-calorie food or neutral stimulus being presented on the opposite side. Mean P3 amplitudes were analyzed. In Go trials, the LOC group’s mean P3 amplitudes were comparable irrespective of distractor category, while for NoGo trials, mean P3 amplitudes were significantly higher when the distractor was a high-calorie food stimulus. This pattern was reversed in the control group. Results are interpreted in light of Gray’s reinforcement sensitivity theory. They might reflect altered processes of behavioral inhibition in adolescents with LOC upon confrontation with visual food stimuli

Telomerverkürzung in der humanen Leberzirrhose sowie Einfluss von Telomerverkürzung im Rahmen chronischer Leberschädigung auf das Überleben, die Organhomeostase und die Entwicklung von hepatozellulären Karzinomen im Mausmodell

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Die Corporate Identity einer Universität als Mittel Ihrer strategischen Positionierung : Erkenntnisse gewonnen aus einem deutsch-amerikanischen Vergleich

Nordamerikanische Universitäten handeln im Hinblick auf die Präsentation ihrer Leistungen konsequent nach marketingstrategischen Vorgaben, was nicht zuletzt durch das universitäre System bedingt ist. Deutsche Universitäten verfolgen im Allgemeinen keine strategisch orientierte Ausrichtung ihrer marketingpolitischen Aktivitäten. Der Grund ist in der universitären Organisation zu suchen, die trotz einer immer weiter steigenden Zahl von Studienanfängern (vgl. Statistisches Bundesamt Deutschland 2002) mit dem Fehlen von Studiengebühren und der Zuweisung der Studienplätze nach Sozial- und erst in zweiter Linie Leistungskriterien konfrontiert ist. Der marketingpolitische Spielraum im Bereich des Preis- und Distributionsmanagements ist daher weitestgehend begrenzt. Die vorliegende Studie zeigt durch die Betrachtung der Marketing-Aktivitäten nordamerikanischer Universitäten Möglichkeiten für deutsche Hochschulen auf, durch strategische Maßnahmen im Bereich der Produkt- und Kommunikationspolitik eine herausragende Stellung gegenüber ihren Wettbewerbern auf dem nationalen und internationalen Bildungsparkett einzunehmen. Um die Gegenüberstellung strukturell vergleichbarerer Einheiten zu gewährleisten, wurde nicht die Gesamtheit der Universitäten betrachtet, sondern lediglich die marketingpolitischen Maßnahmen der von der AACSB akkreditierten US-amerikanischen Business Schools im Vergleich zu denen der deutschen wirtschaftswissenschaftlichen Fakultäten analysiert. Neben der Ableitung von Handlungsempfehlungen durch einen deutsch-amerikanischen Vergleich bestand ein zweites Untersuchungsziel in der Übertragung des Corporate Identity-Konzepts auf Universitäten. Das Konstrukt der Corporate Identity (CI) konkretisiert durch den CI-Mix – Corporate Communication, Corporate Behavior, Corporate Design und Corporate Culture – stellt einen konzeptionellen Rahmen für die Übertragung strategischer produkt- und kommunikationspolitischer Aktivitäten auf die Universität zur Verfügung