Intact soil core experiments reveal that temperature and depth influence microbial community function and impact the fate of nitrogenous fertilizer amendments

The application of nitrogenous fertilizer to agricultural soil has potentially large impacts on environmental quality, including large scale emission of the potent greenhouse gas nitrous oxide and runoff of nitrates. Through their metabolic activities, including nitrification, denitrification and dissimilatory nitrate reduction to ammonium (DNRA), soil microbial communities play an active role in determining the fate of nitrogenous species, thus thorough knowledge of microbial community structure and function is important to understanding ecosystem scale N-fluxes. While much work has been done to understand the role of microbes in soil N-cycling, rarely are such communities studied in ecological context of depth and temperature combined and we hypothesize that diurnal temperature variation, large in surface soils and more narrow at depth, will result in a differential response to N-input. To investigate both the fate of exogenous N-inputs and microbial community and functional response, intact soil cores (0-10 cm and 10-30 cm depth) taken from an agricultural field site in Havana, IL were imbibed with 15N labelled NH4Cl and KNO3 to simulate fertilizer input. The unsaturated cores were then incubated under a summer diurnal temperature regime reflective of natural temperature profiles observed at specified depths (20-35°C shallow, 22-24°C deep). At nine time points over 21 days, replicate cores were deconstructively sampled for pH, NO3-, NH4+, and 15N isotopic analyses. Stable isotope pool dilution was used to calculate gross transformation rates and microbial community structure and function were assessed by T-RFLP and qPCR, respectively. Comparison of 16S rRNA based T-RFLP total community profiles revealed a distinct temporal succession across soil depths, with shifts in community structure corresponding to changes in soil NO3- and NH4+ concentration. While no significant difference in 16 rRNA based communities was evident between depths, a large temporal shift in nitrous oxide reductase gene (nosZ) based denitrifier community structure of was evident after 7 days, resulting in denitrifier communities that were significantly distinct. Additionally, qPCR analysis of relevant functional gene transcripts reveals differential trends in gene expression between depths. These results suggest that while diurnal temperature variation and depth may not significantly alter overall community structure, the functional response of community members to N-input is a function of temperature and these functional differences between soil communities has a direct impact on not only rates of transformation, but also for the timing and magnitude of N2O fluxes

Dynamic Thermal Analysis of a Power Amplifier

This paper presents dynamic thermal analyses of a power amplifier. All the investigations are based on the transient junction temperature measurements performed during the circuit cooling process. The presented results include the cooling curves, the structure functions, the thermal time constant distribution and the Nyquist plot of the thermal impedance. The experiments carried out demonstrated the influence of the contact resistance and the position of the entire cooling assembly on the obtained results.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Distributed Radiation Monitoring System for Linear Accelerators based on CAN Bus

Abstract—Gamma and neutron radiation is produced during the normal operation of linear accelerators like Free-Electron Laser in Hamburg (FLASH) or X-ray Free Electron Laser (X-FEL). Gamma radiation cause general degeneration of electronics devices and neutron fluence can be a reason of soft error in memories and microcontrollers. X-FEL accelerator will be built only in one tunnel, therefore most of electronic control systems will be placed in radiation environment. Exposing control systems to radiation may lead to many errors and unexpected failure of the whole accelerator system. Thus, the radiation monitoring system able to monitor radiation doses produced near controlling systems is crucial. Knowledge of produced radiation doses allows to detect errors caused by radiation, make plans of essential exchange of control systems and prevent accelerator from serious damages. The paper presents the project of radiation monitoring system able to monitor radiation environment in real time

Diagnostic Application for Development of Custom ATCA Carrier Board for LLRF

The Advanced Telecommunications Computing Architecture (ATCA) standard describes a powerful and efficient platform. With multiple integrated solutions like redundancies and intelligent control mechanisms this technology is characterized with reliability estimated at the level of 99.99999 percent. These features make the standard perfect for use in projects like the Free Electron Laser in Hamburg (FLASH) and the X-ray Free Electron Laser (X-FEL) in order to help them meet the requirements of high availability and reliability. The ATCA standard incorporates advanced control systems defined in the Intelligent Platform Management Interface (IPMI) specification as one of the key elements. The entire ATCA implementation retains its functionality as long as the IPMI remains operational. The complexity level of the application increases, which results in preparing it to run and debugging being more difficult to perform. At the same time, only scrupulous elimination of any kind of possible deficiencies can enable the ATCA implementation to offer the desired level of reliability. Thus, diagnostics become crucial, which creates a need for additional tools performing these tasks during the preparations of both hardware and software for the ATCA application. The paper presents application aiding in development of the prototype Carrier Board by enabling the user of external PC station to perform diagnostic and control activities over the Board. It helps in examining all its components at the stage of running the Board, as well as in further operation analysis