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Netzwerk Nagetier-übertragene Pathogene: Monitoring von Hantavirus-Infektionen in Deutschland
(2009)
Göbekli Tepe Newsletter 2014
(2015)
Selected allotropes of phosphorus are investigated
by different levels of density functional theory
(DFT) calculations to evaluate the relative stability orders with a special focus on the role of van der Waals interactions.Phosphorus is an excellent reference system with a large number of allotropes. Starting from low-dimensional molecular (0D, white P) and polymer structures (1D, P nanorods) to layered (2D, black P) and tubular structures (2D and 3D, crystalline forms of red P), covalent structure motifs are interconnected by van der Waals interactions. They are a key factor for the correct energetic description of all P allotropes. A comparative study is carried out within the local density approximation (LDA) and the generalized gradient approximation (GGA), with and without implementation of a dispersion correction by Grimme (GGA-D2). Our intention is to achieve a reasonable agreement of our calculations with experimental data, the plausibility of energy values, and the treatment of long-range interactions. The effect of van der Waals interactions is exemplified for the interlayer distances of black phosphorous and its electronic structure.
Phosphorus displays fascinating structural diversity and the discovery of new modifications continues to attract attention. In this work, a complete stability range of known and novel crystalline allotropes of phosphorus is described for the first time. This includes recently discovered tubular modifications and the prediction of not-yet-known crystal structures of [P12] nanorods and not-yet-isolated [P14] nanorods. Despite significant structural differences, all P allotropes consist of covalent substructures, which are held together by van der Waals interactions. Their correct reproduction by ab initio calculations is a core issue of current research. While some predictions with the established DFT functionals GGA and LDA differ significantly from experimental data in the description of the P allotropes, consistently excellent agreement with the GGA-D2 approach is used to predict the solid structures of the P nanorods.
Zinc oxide is a promising wide band gap semiconductor for future optoelectronic devices. Today ZnO bulk single crystals are grown by three different techniques: hydrothermally, from the melt, and by chemical vapor transport. For our studies, the authors employed in addition a simple and low cost vapor phase method which gives us good quality crystals and flexibility in crystal doping. The as-grown needle-shaped single crystals were characterized by resistivity measurements, scanning electron microscopy, electron backscatter diffraction, and low temperature photoluminescence spectroscopy.
Recently, it was shown that patients with Parkinson's disease (PD) who exhibit an “Alzheimer's disease (AD)-like” pattern of brain atrophy are at greater risk for future cognitive decline. This study aimed to investigate whether this association is domain-specific and whether atrophy associated with brain aging also relates to cognitive impairment in PD. SPARE-AD, an MRI index capturing AD-like atrophy, and atrophy-based estimates of brain age were computed from longitudinal structural imaging data of 178 PD patients and 84 healthy subjects from the LANDSCAPE cohort. All patients underwent an extensive neuropsychological test battery. Patients diagnosed with mild cognitive impairment or dementia were found to have higher SPARE-AD scores as compared to patients with normal cognition and healthy controls. All patient groups showed increased brain age. SPARE-AD predicted impairment in memory, language and executive functions, whereas advanced brain age was associated with deficits in attention and working memory. Data suggest that SPARE-AD and brain age are differentially related to domain-specific cognitive decline in PD. The underlying pathomechanisms remain to be determined.
Simulationsprogramme, wie z. B. die Methode der Finiten Elemente, gehören heute zu den Standardwerkzeugen in der Produktentwicklung. Mit diesen Systemen werden in vielen Bereichen technische und naturwissenschaftliche Probleme mathematisch abgebildet und deren Lösung grafisch aufbereitet. Den Entstehungsprozess des Produkts unterstützen diese Werkzeuge in hohem Maße, die fachlichen Entscheidungen allerdings trifft der Berechnungsingenieur. Dieser sollte für seine Tätigkeit über ein ausreichendes theoretisches und anwendungsspezifisches Fachwissen verfügen und somit auch Kenntnis über mögliche Fehlerquellen besitzen.
Da bis zum Ende des Projekts Fehler in der Analyse nicht ausgeschlossen werden können, verbleibt für den Projektingenieur ein erhebliches fachliches Risiko. Ein konsequentes Prozess- bzw. Qualitätsmanagement kann dazu beitragen, diese fachlichen Risiken zu verringern bzw. zu vermeiden. Mit den fachlichen Risiken verbunden sind stets auch Haftungsrisiken. Hier kann zwischen Ansprüchen aus Vertrag und solchen aus außervertraglicher Haftung unterschieden werden. Zu Letzterem zählen auch Ansprüche aus dem Produkthaftungsgesetz. Grundsätzlich ist das Risiko, für einen Produktfehler zur Verantwortung gezogen zu werden, umso größer, je mehr Verantwortung der Berechnungsingenieur innerhalb des Unternehmens besitzt.
Diese Ausarbeitung soll einen Überblick über das produktrechtliche Haftungsrisiko des Berechnungsingenieurs geben. Somit richtet sich die Thematik insbesondere an Unternehmen und Ingenieure, die Berechnungsdienstleistungen oder Berechnungsleistungen im Rahmen ihrer unternehmensinternen Produktentwicklung ausführen.
The Atacama Desert is well known for the high occurrence of large-scale fog (spatial extents: hundreds of kilometers) emerging as low stratus (LST) decks over the Pacific Ocean. By contrast, the small-scale and heterogeneous occurrence of small-scale fog (hundreds of meters) particularly during summers is widely unconsidered. However, these events are important for the local vegetation and particularly for the biological soil crusts (BSC) that are widely distributed in this extreme ecosystem. Consequently, a case study in a typical fog oasis in the Pan de Azúcar National Park was conducted to test the feasibility combining field measurements, drone profiling, remote sensing and numerical modeling (i) to investigate fog-type specific differences regarding dynamics, physical properties and formation, (ii) to test the applicability of remote sensing technology for fog monitoring based on existing low-resolution and a proposed new high-resolution product and (iii) to estimate the related fog water input to BSCs. Two types of fog were observed. The well-known fog/LST deck emerging from the Pacific Ocean with high water path and large spatial extent was the first type. Fog of the second type was patchier, small-scale and not necessarily connected to the LST over the ocean. Instead, fog formation of the second type was related to thermal breeze systems, which produced shallow clouds containing less water than those of type 1. In general, such small-scale fog events were not captured well by existing remote sensing products but could be detected with the proposed new high-resolution product which provided promising results. Both fog types were important water resources for the BSCs, with approximately 8% to 24% of the fog water flux available to the BSCs at the surface.
The results indicated the feasibility of the proposed methods’ pool to estimate the water budget of BSCs with a high spatial resolution in the future.
Development of a Method for Multiplex Real-Time Analysis of Enzymatic Activity on a Microbead-Chip
(2013)