Validating soil denitrification models based on laboratory N2 and N2O fluxes and underlying processes derived by stable isotope approaches: concept, methods and regulation of measured fluxes

Robust denitrification data suitable to validate soil N2 fluxes in denitrification models are scarce due to methodical limitations and the extreme spatio-temporal heterogeneity of denitrification in soils. Numerical models have become essential tools to predict denitrification at different scales. Model performance could either be tested for total gaseous flux (NO + N2O + N2), individual denitrification products (e.g. N2O and/or NO) or for the effect of denitrification factors (e.g. C-availability, respiration, diffusivity, anaerobic volume, etc.). While there are numerous examples for validating N2O fluxes, there are neither robust field data of N2 fluxes nor sufficiently resolved measurements of control factors used as state variables in the models. Here we present the concept, methods and first results of collecting model validation data. This is part of the coordinated research unit “Denitrification in Agricultural Soils: Integrated Control and Modelling at Various Scales” (DASIM). Novel approaches are used including analysis of stable isotopes, microbial communities, pore structure and organic matter fractions to provide denitrification data sets comprising as much detail on activity and regulation as possible. This will be the basis to validate existing and calibrate new denitrification models that are applied and/or developed by DASIM subprojects. To allow model testing in a wide range of conditions, denitrification control factors are varied in the initial settings (pore volume, plant residues, mineral N, pH) but also over time, where moisture, temperature, and mineral N are manipulated according to typical time patterns in the field. This is realized by including precipitation events, fertilization (via irrigation), drainage (via water potential) and temperature in the course of incubations. Moreover, oxygen concentration is varied to simulate anaerobic events. The 15N gas flux method is employed to quantify N2 and N2O emissions from various pools and processes

Fitting the Professional to the Job: Idealism and Realism

This article examines a number of factors related to job satisfaction among financial aid professionals. How well the job matches the individual\u27s expectations of employment, regardless of intrinsic or extrinsic job orientation, accounts for the greater proportion of explained job satisfaction. The implications of these findings for management of financial aid offices are discussed. An earlier version of this paper was presented to the Southwestern Sociological Association

Cultivated ties and strategic communication: Do international environmental secretariats tailor information to increase their bureaucratic reputation?

The past few years have witnessed a growing interest among scholars and policy-makers in the interplay of international bureaucracies with civil society organizations, other non-profit entities, and the private sector. This article extends the state of research by investigating whether and how secretariats try to strengthen their reputation within their respective policy regimes through information provision and alliance building. Based on reputation theory, the article argues that ties cultivated with stakeholders as well as appearance and presentation of information are decisive in this regard. Methodologically, the study implements a mixed-methods design that combines a quantitative survey with social network analysis and qualitative content analysis of interviews with stakeholders within the climate and biodiversity regime. We show that the secretariats of the Convention on Biological Diversity (CBD) and the United Nations Framework Convention on Climate Change (UNFCCC) maintain relationships with a wide range of state and non-state actors to enhance their reputation. Moreover, different types of actors receive different types of information from the two secretariats studied. Our findings reveal that both secretariats use their limited resources for investing strategically into networks with different types of actors (in the broader transnational policy network), either via the tailored provision of information or through strategic networking with multipliers. They also indicate that reputation does not simply depend on characteristics of bureaucracies, but also on framework conditions and different communication strategies.info:eu-repo/semantics/acceptedVersio

Brokering climate action: the UNFCCC secretariat between parties and non-party stakeholders

Our article aims to better understand the role of the secretariat of the United Nations Framework Convention on Climate Change (UNFCCC) in the increasingly complex global climate governance structure. We employ an innovative approach to addressing this issue by systematically examining the climate secretariat’s relations with the main groups of actors involved in this policy domain, in particular with nonparty actors. In a first step, we use social network analysis (SNA) to examine the secretariat’s relations with nonparty and state stakeholders and to identify its position in the UNFCCC policy network. An understanding of where the climate secretariat stands in the global climate governance network and which actors it interacts with most allows us to draw preliminary conclusions about the ways in which it connects with other stakeholders to influence global climate policy outputs. In a second step, we conduct thirty-three semistructured interviews to corroborate the results of the SNA. Our findings lend support to the argument that the climate secretariat may gradually be moving from a rather neutral and instrumental stance to playing a proactive and influential role in international climate governance. It aims to increase its political influence by establishing strategic links to actors other than the formal negotiation parties.info:eu-repo/semantics/acceptedVersio

Validating soil denitrification models based on laboratory N2 and N2O fluxes and underlying processes: evaluation of DailyDayCent and COUP models

Denitrification is an anaerobic key process by microbes where the NO3- is step-by-step reduced and emitted as NO, N2O and finally N2 gas from the soil. Accurate knowledge on denitrification dynamics is important because the N2O is further reduced to N2 and constitutes the main emission source of this greenhouse gas from agricultural soils. Hence, our understanding and ability to quantify soil denitrification is crucial for mitigating nitrogen fertilizer loss as well as for reducing N2O emissions. Models can be an important tool to predict mitigation effects and help to develop climate smart mitigation strategies. Ideally, commonly used biogeochemical models could provide adequate predictions of denitrification processes of agricultural soils but often simplified process descriptions and inadequate model parameters prevent models from simulating adequate fluxes of N2 and N2O on field scale. Model development and parametrization often suffers from limited availability of empirical data describing denitrification processes in agricultural soils. While in many studies N2O emissions are used to develop and train models, detailed measurements on NO, N2O, N2 fluxes and concentrations and related soil conditions are necessary to develop and test adequate model algorithms. To address this issue the coordinated research unit „Denitrification in Agricultural Soils: Integrated Control and Modelling at Various Scales (DASIM)” was initiated to more closely investigate N-fluxes caused by denitrification in response to environmental effects, soil properties and microbial communities. Here, we present how we will use these data to evaluate common biogeochemical process models (DailyDayCent, Coup) with respect to modeled NO, N2O and N2 fluxes from denitrification. The models are used with different settings. The first approximation is the basic “factory” setting of the models. The next step would show the precision in the results of the modeling after adjusting the appropriate parameters from the result of the measurement values and the “factory” results. The better adjustment and the well-controlled input and output measured parameters could provide a better understanding of the probable scantiness of the tested models which will be a basis for future model improvement

Information Flow and Staff Contact: A Quick Evaluation of Financial Aid

The authors examine the relationship between financial aid staff and students and attempt to analyze how the experience at one institution might provide some insight. The problem is viewed from the client perspective based upon day to day contact with various services provided to students by the financial aid office

Crystal Growth with Oxygen Partial Pressure of the BaCuSi2O6 and Ba1-xSrxCuSi2O6 Spin Dimer Compounds

BaCuSi2O6 is a quasi-two-dimensional spin dimer system and a model material for studying Bose-Einstein condensation (BEC) of magnons in high magnetic fields. The new Bai(1-x)Sr(x)CuSi(2)O(6) mixed system, which can be grown with x <= 0.3, and BaCuSi2O6, both grown by using a crystal growth method with enhanced oxygen partial pressure, have the same tetragonal structure (I4(1)/acd) at room temperature. The mixed system shows no structural phase transition so that the tetragonal structure is stable down to low temperatures. The oxygen partial pressure acts as a control parameter for the growth process. A detailed understanding of the crystal structure depending on the oxygen content will enable the study of the spin dynamics of field-induced order states in this model magnetic compound of high current interest with only one type of dimer layers, which shows the same distance between the Cu atoms, in the structure

Sound-propagation gap in fluid mixtures

We discuss the behavior of the extended sound modes of a dense binary hard-sphere mixture. In a dense simple hard-sphere fluid the Enskog theory predicts a gap in the sound propagation at large wave vectors. In a binary mixture the gap is only present for low concentrations of one of the two species. At intermediate concentrations sound modes are always propagating. This behavior is not affected by the mass difference of the two species, but it only depends on the packing fractions. The gap is absent when the packing fractions are comparable and the mixture structurally resembles a metallic glass.Comment: Published; withdrawn since ordering in archive gives misleading impression of new publicatio