Modelling understorey dynamics in temperate forests under global change : challenges and perspectives

The understorey harbours a substantial part of vascular plant diversity in temperate forests and plays an important functional role, affecting ecosystem processes such as nutrient cycling and overstorey regeneration. Global change, however, is putting these understorey communities on trajectories of change, potentially altering and reducing their functioning in the future. Developing mitigation strategies to safeguard the diversity and functioning of temperate forests in the future is challenging and requires improved predictive capacity. Process-based models that predict understorey community composition over time, based on first principles of ecology, have the potential to guide mitigation endeavours but such approaches are rare. Here, we review fourteen understorey modelling approaches that have been proposed during the last three decades. We evaluate their inclusion of mechanisms that are required to predict the impact of global change on understorey communities. We conclude that none of the currently existing models fully accounts for all processes that we deem important based on empirical and experimental evidence. Based on this review, we contend new models are needed to project the complex impacts of global change on forest understoreys. Plant functional traits should be central to such future model developments, as they drive community assembly processes and provide valuable information on the functioning of the understorey. Given the important role of the overstorey, a coupling of understorey models to overstorey models will be essential to predict the impact of global change on understorey composition and structure, and how it will affect the functioning of temperate forests in the future

Structure and Kinematics of the Vortex System in Axial Turbomachines

This investigation models the kinematics of the vortex system of an encased axial turbomachine at part load and overload applying analytical methods. So far, the influence of the casing and the tip clearance on the kinematics was solved separately. The vortex system is composed of a hub, bound and tip vortices. For the nominal operating point φ ≈ φ(opt) and negligible induction, the tip vortices transform into a screw. For part load operation φ → 0, the tip vortices wind up to a vortex ring, i.e. the pitch of the screw vanishes. For overload operation φ → ∞, the vortex system of the turbomachine forms a horseshoe, i.e. the pitch of the screw becomes infinite. Both, hub and tip vortices, are semi-infinite, straight vortex filaments

The Role of Universities Within the Qualification and Verification Process of EuP Requirements for Turbomachines using the Example of Rotodynamics Pumps

Besides general Energy using Products (EuP) related issues concerning the qualification approaches for rotodynamic pumps this paper demonstrates a practical example how universities are able to support the work of market surveillance by providing their neutral scientific expertise as well as their infrastructure in the frame of product verification. This example based on the work achieved within a small pilot project funded by the Ministry of Environment, Climate and Energy Economics of Baden-Württemberg respectively the affiliated market surveillance authority. The small project consists of a round robin test to verify the MEI (Minimum Efficiency Index) of a single stage end suction centrifugal pump

A newly described strain of Eimeria arloingi (strain A) belongs to the phylogenetic group of ruminant-infecting pathogenic species, which replicate in host endothelial cells in vivo

Coccidiosis caused by Eimeria species is an important disease worldwide, particularly in ruminants and poultry. Eimeria infection can result in significant economic losses due to costs associated with treatment and slower growth rates, or even with mortality of heavily infected individuals. In goat production, a growing industry due to increasing demand for caprine products worldwide, coccidiosis is caused by several Eimeria species with E. arloingi and E. ninakohlyakimovae the most pathogenic. The aims of this study were genetic characterization of a newly isolated European E. arloingi strain (A) and determination of phylogenetic relationships with Eimeria species from other ruminants. Therefore, a DNA sequence of E. arloingi strain (A) containing 2290 consensus nucleotides (the majority of 18S rDNA, complete ITS-1 and 5.8S sequences, and the partial ITS-2) was amplified and phylogenetic relationship determined with the most similar sequences available on GenBank. The phylogenetic tree presented a branch constituted by bovine Eimeria species plus E. arloingi, and another one exclusively populated by ovine Eimeria species. Moreover, E. arloingi, E. bovis and E. zuernii, which all replicate in host intestinal endothelial cells of the lacteals, were found within the same cluster. This study gives new insights into the evolutionary phylogenetic relationships of this newly described caprine Eimeria strain and confirmed its close relationship to other highly pathogenic ruminant Eimeria species characterized by macromeront formation in host endothelial cells of the central lymph capillaries of the small intestine

Impact of CYP2C19 variant genotypes on clinical efficacy of antiplatelet treatment with clopidogrel: systematic review and meta-analysis

Objective To evaluate the accumulated information from genetic association studies investigating the impact of variants of the cytochrome P450 (CYP) 2C19 genotype on the clinical efficacy of clopidogrel

Development of a Standardized Approach to Assess the Energy Efficiency of Booster Pump Units in the Sense of an Extended Product

With regard to the so called extended product approach (EPA), an appropriate methodology to qualify respectively verify these extended products has been successfully developed at the Institute for Fluid Systems of Technische Universität Darmstadt – supported by Europump – for single pump units. The EPA is a measure to meet the energy related products (ErP) and energy using products (EuP) requirements of the European Commission. Based on the experience of this work Europump decided to expand the EPA also to booster pump units, which normally consist of multiple pumps as well as further hydraulic and electric components to ensure the specific demands of pressure boosting within buildings. A characteristic rating is needed to compare and quantify the energy efficiency of booster pump units in a standardized way. The development of a draft standard proposal for further regulation is the final objective of this work. As a result the energy efficiency index (EEI) as a normalized weighted average of the electrical input power for a booster pump unit operating at different duty points at part load is introduced. A standardized load-time profile and a pressure control curve are defined in order to compare lifetime efficiency and part load behaviour. The EEI will be determined using both an experimental and semi-analytical approach. Main task of the experimental work is the development of a measurement procedure for the EEI determination, which can be summarized as a realization of sensitivity studies in order to deduce all major effects on the EEI for a subsequent standard elaboration. This includes the definition of needed accuracy and acceptable tolerances of flow-adjustment and used sensors as well as the examination of parameters affecting the power consumption of the booster pump unit. Besides, steady state operation for each duty point has to be guaranteed. A method for non-adjustable duty points within the given constraints has to be implemented which is attended by the exertion of penalties in EEI for overshooting. The tasks of the Institute for Fluid Systems of Technische Universität Darmstadt are the development and neutral assessment of all required measurement procedures. Besides the experimental work, a semi-analytical approach is developed which allows calculating the electrical input power and thus the EEI with reduced experimental effort in future. The resulting semi-analytical model (SAM) is based on empirical data for frequency converters, motors and pumps as well as analytical laws describing the physics of booster system behaviour. A further advantage of SAM is the possibility of systematic determination of EEI values for booster units consisting of components delivered by different manufacturers

Effects of Silver Nanoparticles on Primary Mixed Neural Cell Cultures: Uptake, Oxidative Stress and Acute Calcium Responses

In the body, nanoparticles can be systemically distributed and then may affect secondary target organs, such as the central nervous system (CNS). Putative adverse effects on the CNS are rarely investigated to date. Here, we used a mixed primary cell model consisting mainly of neurons and astrocytes and a minor proportion of oligodendrocytes to analyze the effects of well-characterized 20 and 40 nm silver nanoparticles (SNP). Similar gold nanoparticles served as control and proved inert for all endpoints tested. SNP induced a strong size-dependent cytotoxicity. Additionally, in the low concentration range (up to 10 μg/ml of SNP), the further differentiated cultures were more sensitive to SNP treatment. For detailed studies, we used low/medium dose concentrations (up to 20 μg/ml) and found strong oxidative stress responses. Reactive oxygen species (ROS) were detected along with the formation of protein carbonyls and the induction of heme oxygenase-1. We observed an acute calcium response, which clearly preceded oxidative stress responses. ROS formation was reduced by antioxidants, whereas the calcium response could not be alleviated by antioxidants. Finally, we looked into the responses of neurons and astrocytes separately. Astrocytes were much more vulnerable to SNP treatment compared with neurons. Consistently, SNP were mainly taken up by astrocytes and not by neurons. Immunofluorescence studies of mixed cell cultures indicated stronger effects on astrocyte morphology. Altogether, we can demonstrate strong effects of SNP associated with calcium dysregulation and ROS formation in primary neural cells, which were detectable already at moderate dosage

uptake, intracellular distribution and cellular responses

Silver nanoparticles (SNP) are among the most commercialized nanoparticles worldwide. They can be found in many diverse products, mostly because of their antibacterial properties. Despite its widespread use only little data on possible adverse health effects exist. It is difficult to compare biological data from different studies due to the great variety in sizes, coatings or shapes of the particles. Here, we applied a novel synthesis approach to obtain SNP, which are covalently stabilized by a small peptide. This enables a tight control of both size and shape. We applied these SNP in two different sizes of 20 or 40 nm (Ag20Pep and Ag40Pep) and analyzed responses of THP-1-derived human macrophages. Similar gold nanoparticles with the same coating (Au20Pep) were used for comparison and found to be non-toxic. We assessed the cytotoxicity of particles and confirmed their cellular uptake via transmission electron microscopy and confocal Raman microscopy. Importantly a majority of the SNP could be detected as individual particles spread throughout the cells. Furthermore we studied several types of oxidative stress related responses such as induction of heme oxygenase I or formation of protein carbonyls. In summary, our data demonstrate that even low doses of SNP exerted adverse effects in human macrophages