Effects of aerobic and anaerobic conditions on P, N, Fe, Mn, and Hg accumulation in waters overlaying profundal sediments of an oligo-mesotrophic lake

Concentrations of key nutrients and metals in water overlaying profundal sediments were evaluated in replicate experimental chambers containing undisturbed sediment-water interface samples from Deer Lake, an oligo-mesotrophic lake in eastern Washington. Chambers were incubated under three sequential phases: aerobic (21d), anaerobic (27d), and second aerobic (14d). In general, nutrients and metals in chamber water were lower under aerobic versus anaerobic conditions. However, in some cases compounds anticipated to appear only under anaerobic conditions, including ammonia, phosphate, and manganese, were observed during aerobic conditions. Correlation analysis elucidated a number of interactions between compounds. Phosphate correlated significantly (p<0.05) with iron during all incubation phases, suggesting that phosphorus cycling was controlled by iron. Cycling of nitrate and ammonia was tightly and significantly coupled under aerobic conditions. During both aerobic phases, nitrate increased while ammonia decreased, likely as a result of biological nitrification. Finally, mercury appeared during mildly reducing conditions and showed a significant correlation with manganese during the anaerobic phase, suggesting that Mn oxide reduction was the source of Hg in chamber water.     

Thoughtful brute-force attack of the RERS 2012 and 2013 Challenges

The Rigorous Examination of Reactive Systems’ (rers) Challenges provide a forum for experimental evaluation based on specifically synthesized benchmark suites. In this paper, we report on our ‘brute-force attack’ of the rers 2012 and 2013 Challenges. We connected the rers problems to two state-of-the-art explicit state model checkers: LTSmin and Spin. Apart from an effective compression of the state vector, we did not analyze the source code of the problems. Our brute-force approach was successful: it won both editions of the rers Challenge.     

Advanced data processing in KRISYS: modeling concepts, implementation techniques, and client/server issues

The increasing power of modern computers is steadily opening up new application domains for advanced data processing such as engineering and knowledge-based applications. To meet their requirements, concepts for advanced data management have been investigated during the last decade, especially in the field of object orientation. Over the last couple of years, the database group at the University of Kaiserslautern has been developing such an advanced database system, the KRISYS prototype. In this article, we report on the results and experiences obtained in the course of this project. The primary objective for the first version of KRISYS was to provide semantic features, such as an expressive data model, a set-oriented query language, deductive as well as active capabilities. The first KRISYS prototype became completely operational in 1989. To evaluate its features and to stabilize its functionality, we started to develop several applications with the system. These experiences marked the starting point for an overall redesign of KRISYS. Major goals were to tune KRISYS and its query-processing facilities to a suitable client/server environment, as well as to provide elaborate mechanisms for consistency control comprising semantic integrity constraints, multi-user synchronization, and failure recovery. The essential aspects of the resulting client/server architecture are embodied by the client-side data management needed to effectively support advanced applications and to gain the required system performance for interactive work. The project stages of KRISYS properly reflect the essential developments that have taken place in the research on advanced database systems over the last years. Hence, the subsequent discussions will bring up a number of important aspects with regard to advanced data processing that are of significant general importance, as well as of general applicability to database systems. Received June 18, 1996 / Accepted November 11, 1997     

Analyzing a self-managed CHP system for greenhouse cultivation as a profitable way to reduce CO2-emissions

To counter global warming, a transition to a low-carbon economy is needed. The greenhouse sector can contribute by installing Combined Heat and Power (CHP) systems, known for their excellent energy efficiency. Due to the recent European liberalization of the energy market, glass horticulturists have the opportunity to sell excess electricity to the market and by tailored policy and support measures, regional governments can fill the lack of technical and economic knowledge, causing initial resistance. This research investigates the economic and environmental opportunities using two detailed cases applying a self managed cogeneration system. The Net Present Value is calculated to investigate the economic feasibility. The Primary Energy Saving, the CO₂ Emission Reduction indicator and an Emission Balance are applied to quantify the environmental impact. The results demonstrate that a self-managed CHP system is economic viable and that CO₂ emissions are reduced.     

Ramping down a clinical 3 T scanner: a journey into MRI and MRS at 0.75 T

Object

Lower-field MR is reemerging as a viable, potentially cost-effective alternative to high-field MR, thanks to advances in hardware, sequence design, and reconstruction over the past decades. Evaluation of lower field strengths, however, is limited by the availability of lower-field systems on the market and their considerable procurement costs. In this work, we demonstrate a low-cost, temporary alternative to purchasing a dedicated lower-field MR system.

Materials and Methods

By ramping down an existing clinical 3 T MRI system to 0.75 T, proton signals can be acquired using repurposed ¹³C transmit/receive hardware and the multi-nuclei spectrometer interface. We describe the ramp-down procedure and necessary software and hardware changes to the system.

Results

Apart from presenting system characterization results, we show in vivo examples of cardiac cine imaging, abdominal two- and three-point Dixon-type water/fat separation, water/fat-separated MR Fingerprinting, and point-resolved spectroscopy. In addition, the ramp-down approach allows unique comparisons of, e.g., gradient fidelity of the same MR system operated at different field strengths using the same receive chain, gradient coils, and amplifiers.

Discussion

Ramping down an existing MR system may be seen as a viable alternative for lower-field MR research in groups that already own multi-nuclei hardware and can also serve as a testing platform for custom-made multi-nuclei transmit/receive coils.

     

Access to High-Purity 7mG-cap RNA in Substantial Quantities by a Convenient All-Chemical Solid-Phase Method

Given the importance of mRNA with 5’-cap, easy access to RNA substrates with different ^7mG caps, of high quality and in large quantities is essential to elucidate the roles of RNA and the regulation of underlying processes. In addition to existing synthetic routes to 5’-cap RNA based on enzymatic, chemical or chemo-enzymatic methods, we present here an all-chemical method for synthetic RNA capping. The novelty of this study lies in the fact that the capping reaction is performed on solid-support after automated RNA assembly using commercial 2’-O-propionyloxymethyl ribonucleoside phosphoramidites, which enable final RNA deprotection under mild conditions while preserving both ^7mG-cap and RNA integrity. The capping reaction is efficiently carried out between a 5’-phosphoroimidazolide RNA anchored on the support and ^7mGDP in DMF in the presence of zinc chloride. Substantial amounts of ^7mG-cap RNA (from 1 to 28 nucleotides in length and of any sequence with or without internal methylations) containing various cap structures (^7mGpppA, ^7mGpppA_m, ^7mGppp^m6A, ^7mGppp^m6A_m, ^7mGpppG, ^7mGpppG_m) were obtained with high purity after IEX-HPLC purification. This capping method using solid-phase chemistry is convenient to perform and provides access to valuable RNA substrates as useful research tools to unravel specific issues regarding cap-related processes.