1,853 research outputs found

    Numerical Methods for Uncertainty Quantification in Gas Network Simulation

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    When modeling the gas flow through a network, some elements such as pressure control valves can cause kinks in the solution. In this thesis we modify the method of simplex stochastic collocation such that it is applicable to functions with kinks. First, we derive a system of partial differential and algebraic equations describing the gas flow through different elements of a network. Restricting the gas flow to an isothermal and stationary one, the solution can be determined analytically. After introducing some common methods for the forward propagation of uncertainty, we present the method of simplex stochastic collocation to approximate functions of uncertain parameters. By utilizing the information whether a pressure regulator is active or not in the current simulation, we improve the method such that we can prove algebraic convergence rates for functions with kinks. Moreover, we derive two new error estimators for an adaptive refinement and show that multiple refinements are possible. Conclusively, several numerical results for a real gas network are presented and compared with standard methods to demonstrate the significantly better convergence results

    Modulation of asthma and allergy by addressing toll-like receptor 2

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    Toll-like receptors play an important role in innate and adaptive immunity and in balancing immune responses with tolerance. TLR2 is related to protection against allergies and allergic asthma by sensing pathogen associated patterns as lipoproteins and lipopeptides. A constant Th1 triggering is thought to prevent Th2 related disorders

    Impact of soil management practices on soil fertility and disease suppressiveness

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    Soil management practices are targeted to provide adequate crop nutrition and to ensure durable soil fertility and to avoid negative environmental impacts. Soil management also aims to reduce pest and disease pressure on crops. Organic farming is believed to increase soil suppressiveness towards soil-borne diseases as well aerial diseases. In this paper we will discuss the potential of soil manage-ment as a tool to improve disease suppressiveness in practice

    Die Erstellung von Erklärvideos als Prüfungsformat in der Wahrnehmung von Grundschullehramtsstudierenden

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    Als zentraler Bestandteil der universitären Ausbildung werden zahlreiche Erwartungen an den Einsatz von Prüfungen gestellt: Sie sollen Studierenden Rückmeldung zu ihren Lernprozessen geben und sie dazu motivieren, sich vertieft mit den Inhalten auseinanderzusetzen. Inwiefern alternative Prüfungsformate wie die Erstellung von Erklärvideos aus Sicht von Grundschullehramtsstudierenden solche Funktionen erfüllen, wird im Folgenden untersucht. (DIPF/Orig.

    Organic Acid Excretion in Penicillium ochrochloron Increases with Ambient pH

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    Despite being of high biotechnological relevance, many aspects of organic acid excretion in filamentous fungi like the influence of ambient pH are still insufficiently understood. While the excretion of an individual organic acid may peak at a certain pH value, the few available studies investigating a broader range of organic acids indicate that total organic acid excretion rises with increasing external pH. We hypothesized that this phenomenon might be a general response of filamentous fungi to increased ambient pH. If this is the case, the observation should be widely independent of the organism, growth conditions, or experimental design and might therefore be a crucial key point in understanding the function and mechanisms of organic acid excretion in filamentous fungi. In this study we explored this hypothesis using ammonium-limited chemostat cultivations (pH 2–7), and ammonium or phosphate-limited bioreactor batch cultivations (pH 5 and 7). Two strains of Penicillium ochrochloron were investigated differing in the spectrum of excreted organic acids. Confirming our hypothesis, the main result demonstrated that organic acid excretion in P. ochrochloron was enhanced at high external pH levels compared to low pH levels independent of the tested strain, nutrient limitation, and cultivation method. We discuss these findings against the background of three hypotheses explaining organic acid excretion in filamentous fungi, i.e., overflow metabolism, charge balance, and aggressive acidification hypothesis

    Empirical insights into the benefit from implementing smart contracts

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    Smart contracts are highly relevant due to their support for new decentralized business models and processes. We empirically investigate the benefit of implementing smart contracts. Our approach measures the benefit by capturing the impact of implementing smart contracts on processes directly. Thus, our research supersedes previous research that uses deductive approaches for deriving beneficial effects from technical and architectural properties of smart contracts and blockchains. We conduct a systematic approach using the aspects cost, quality, time and flexibility, and their impact on the four process phases interest, agreement, fulfillment, and assessment. Our research enables decision-makers to make decisions on implementing smart contracts more precisely. Furthermore, decision-makers become able to develop more target-oriented initiatives

    Identifizierung und Charakterisierung der krankheitsunterdrückenden Mikroorganismen beim Komposteinsatz

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    Einleitung • Bodenbürtige Krankheiten verursachen grosse Schäden und sind schwierig zu kontrollieren. • Kompost-Zugabe kann Druck durch bodenbürtige Krankheitserreger reduzieren • ABER: Nicht jeder Komposteinsatz ist erfolgreich. • Möglicher Grund ist die sich während des Kompost-Reifeprozesses laufend ändernde mikrobielle Zusammensetzung. • Es ist weitgehend noch unbekannt, welche mikrobiellen Konsortien wichtig für die suppressive Wirkung von Komposten sind

    Wolf Responses to Experimental Human Approaches Using High-Resolution Positioning Data

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    Humans pose a major mortality risk to wolves. Hence, similar to how prey respond to predators, wolves can be expected to show anti-predator responses to humans. When exposed to a threat, animals may show a fight, flight, freeze or hide response. The type of response and the circumstances (e.g., distance and speed) at which the animal flees are useful parameters to describe the responses of wild animals to approaching humans. Increasing knowledge about behavioral responses of wolves toward humans might improve appropriate management and decrease conflicts related to fear of wolves. We did a pilot study by conducting 21 approach trials on seven GPS-collared wolves in four territories to investigate their responses to experimental human approaches. We found that wolves predominantly showed a flight response (N = 18), in a few cases the wolf did not flee (N = 3), but no wolves were seen or heard during trials. When wolves were downwind of the observer the flight initiation distance was significantly larger than when upwind, consistent with the hypothesis that conditions facilitating early detection would result in an earlier flight. Our hypothesis that early detection would result in less intense flights was not supported, as we found no correlation between flight initiation distances and speed, distance or straightness of the flight. Wolves in more concealed habitat had a shorter flight initiation distance or did not flee at all, suggesting that perceived risk might have been affected by horizontal visibility. Contrary to our expectation, resettling positions were less concealed (larger horizontal visibility) than the wolves' initial site. Although our small number of study animals and trials does not allow for generalizations, this pilot study illustrates how standardized human approach trials with high-resolution GPS-data can be used to describe wolf responses at a local scale. In continuation, this method can be applied at larger spatial scales to compare wolf flight responses within and between populations and across anthropogenic gradients, thus increasing the knowledge of wolf behavior toward humans, and potentially improving coexistence with wolves across their range
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