49 research outputs found

    Listeria pathogenesis and molecular virulence determinants

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    The gram-positive bacterium Listeria monocytogenes is the causative agent of listeriosis, a highly fatal opportunistic foodborne infection. Pregnant women, neonates, the elderly, and debilitated or immunocompromised patients in general are predominantly affected, although the disease can also develop in normal individuals. Clinical manifestations of invasive listeriosis are usually severe and include abortion, sepsis, and meningoencephalitis. Listeriosis can also manifest as a febrile gastroenteritis syndrome. In addition to humans, L. monocytogenes affects many vertebrate species, including birds. Listeria ivanovii, a second pathogenic species of the genus, is specific for ruminants. Our current view of the pathophysiology of listeriosis derives largely from studies with the mouse infection model. Pathogenic listeriae enter the host primarily through the intestine. The liver is thought to be their first target organ after intestinal translocation. In the liver, listeriae actively multiply until the infection is controlled by a cell-mediated immune response. This initial, subclinical step of listeriosis is thought to be common due to the frequent presence of pathogenic L. monocytogenes in food. In normal indivuals, the continual exposure to listerial antigens probably contributes to the maintenance of anti-Listeria memory T cells. However, in debilitated and immunocompromised patients, the unrestricted proliferation of listeriae in the liver may result in prolonged low-level bacteremia, leading to invasion of the preferred secondary target organs (the brain and the gravid uterus) and to overt clinical disease. L. monocytogenes and L. ivanovii are facultative intracellular parasites able to survive in macrophages and to invade a variety of normally nonphagocytic cells, such as epithelial cells, hepatocytes, and endothelial cells. In all these cell types, pathogenic listeriae go through an intracellular life cycle involving early escape from the phagocytic vacuole, rapid intracytoplasmic multiplication, bacterially induced actin-based motility, and direct spread to neighboring cells, in which they reinitiate the cycle. In this way, listeriae disseminate in host tissues sheltered from the humoral arm of the immune system. Over the last 15 years, a number of virulence factors involved in key steps of this intracellular life cycle have been identified. This review describes in detail the molecular determinants of Listeria virulence and their mechanism of action and summarizes the current knowledge on the pathophysiology of listeriosis and the cell biology and host cell responses to Listeria infection. This article provides an updated perspective of the development of our understanding of Listeria pathogenesis from the first molecular genetic analyses of virulence mechanisms reported in 1985 until the start of the genomic era of Listeria research

    Forschungsbericht – Solarthermie 2000 Teilprogramm 3 – Solar unterstützte Nahwärmeversorgung Pilotanlage Solaris Chemnitz

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    Im Forschungs- und Demonstrationsprogramm Solarthermie 2000, Teilprogramm 3 wurden von 1993 bis 2002 solar unterstützte Nahwärmesysteme konzipiert, errichtet und vermessen. Wesentliche Ziele dieses Programms waren die Demonstration der Durchführbarkeit, der Nachweis der Kostenreduktion bei großen Systemen und die Weiterentwicklung sowie Untersuchung dieser Technik. Das in diesem Bericht dokumentierte Forschungsvorhaben ist ein Projekt in oben genanntem Vorhaben und zeichnet sich durch folgende Parameter aus: - Energiequelle: Kollektorfelder mit einer Absorberfläche von 538,5 m² (Vakuum-Röhrenkollektoren) und BHKW, - saisonaler Speicher: 8000 m³ Kies-Wasser-Speicher, - Verbraucher: Heizung eines Bürogebäudes Das Vorhaben wurde durch die Autoren wissenschaftlich-technisch betreut. Die Erkenntnisse von der Konzeption bis zur funktionstüchtigen Anlage werden im Bericht erläutert. Auf Grund der meßtechnischen Untersuchung liegen detaillierte Ergebnisse zum Systemverhalten, zur Effizienz der Bauteile und des Systems vor

    Advanced concepts for renewable energy supply of data centres

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    The rapid increase of cloud computing, high performance computing (HPC) and the vast growth in Internet and Social Media use have aroused the interest in energy consumption and the carbon footprint of Data Centres. Data Centres primarily contain electronic equipment used for data processing (servers), data storage (storage equipment), and communications (network equipment). Collectively, this equipment processes, stores, and transmits digital information and is known as information technology (IT) equipment. Advanced Concepts for Renewable Energy Supply of Data Centres introduces a number of technical solutions for the supply of power and cooling energy into Data Centres with enhanced utilisation of renewable energy sources in order to achieve low energy Data Centres. Because of the high energy density nature of these unique infrastructures, it is essential to implement energy efficiency measures and reduce consumption before introducing any renewable energy source. A holistic approach is used with the objective of integrating many technical solutions such as management of the IT (Information Technology) load, efficient electrical supply to the IT systems, Low-Ex air-conditioning systems, interaction with district heating and cooling networks, re-use of heat, free cooling (air, seawater, groundwater), optimal use of heat and cold storage, electrical storage and integration in smart grids. This book is therefore a catalogue of advanced technical concepts that could be integrated into Data Centres portfolio in order to increase the overall efficiency and the share of renewable energies in power and cooling supply. Based on dynamic energy models implemented in TRNSYS some concepts are deeply evaluated through yearly simulations. The results of the simulation are illustrated with Sankey charts, where the energy flows per year within the subsystems of each concept for a selected scenario are shown, and graphs showing the results of parametric analysis. A set of environmental metrics (as the non-renewable primary energy) and financial metrics (CAPEX and OPEX) as well of energy efficiency metrics like the well-known PUE, are described and used to evaluate the different technical concepts.Note.- EUR 6,000 BPC fee funded by the EC FP7 Post-Grant Open Access Pilo

    Bautechnik-Forum Chemnitz 2004

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    Inhalt: Nachhaltiger Stadtumbau und Erneuerbare Energien - Ansatz und Konzepte einer ökologischen Stadtentwicklung Wohnprojekt Dresden Pillnitz - Innovatives Energiekonzept für zwei Mehrfamilienhäuser in Passivhausbauweise Tiefbautechnik in der Praxis - Die spektakuläre Gablenzbach-Sanierung Mauern für die Ewigkeit - Rekonstruktion, Sanierung und Neubau von Mauerwerksbauten Wärmebrückenbeheizung - Ein Widerspruch? Solares Heizen mit Großanlagen - Chancen und Perspektiven Bauphysikalische Wertung von belüfteten und nicht belüfteten Dächern Kritische Aspekte zum sommerlichen Wärmeschutz \u96 Vorbemessun

    Optimizing industrial robot arms

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