585 research outputs found
Reduzierte Bodenbearbeitung im Ăkologischen Landbau: Einfluss auf Leistung und Struktur der Bodenmikroorganismengemeinschaft
Problemstellung/Ziele: Im Projekt âĂkologische Bodenbewirtschaftungâ (PĂB) der Stiftung Ăkologie und Landbau, Bad DĂŒrckheim, wird seit 1995 am Standort Rommersheim, Rheinhessen, eine differenzierte Grundbodenbearbeitung mit den Varianten Pflug (P), Zweischichtenpflug (LP) und Schichtengrubber (LC) durchgefĂŒhrt. Ziel der Untersuchungen war es, vertiefende Einsichten in die Reaktion der mikrobiellen Biomasse auf die differenzierte Bodenbearbeitung unter den besonderen Bedingungen des Ăkologischen Landbaus zu erhalten.
Hypothesen: Eine reduzierte (LP) und konservierende (LC) Bodenbearbeitung fĂŒhrt im Vergleich zum Pflug (P) zu einer Anreicherung und Sequestrierung sowie einer qualitativen Modifikation von organischer Bodensubstanz und mikrobieller Biomasse. Die funktionelle und strukturelle DiversitĂ€t der Bodenmikroorganismen-Gemeinschaft wird hierdurch ebenfalls modifiziert.
Methoden: Im FrĂŒhjahr 2001 wurden Bodenproben aus GrĂŒnbrache-Parzellen in vierfacher Wiederholung je Bodenbearbeitungsvariante differenziert nach Ober- (0-15cm) und Unterkrume (15-25cm) entnommen und hinsichtlicher der Gehalte an organischer Substanz (trockene Veraschung), mikrobieller Biomasse (CFE-C) und AktivitĂ€t (Infrarotgasanalysator) sowie der funktionellen DiversitĂ€t (community level substrate utilization profiles â BIOLOG GN2) untersucht. Die strukturelle DiversitĂ€t wurde mittels Phospholipid-FettsĂ€ure (PLFA) und Phospholipid-Etherlipide (PLEL) âMuster analysiert. ErgĂ€nzend wurde die QualitĂ€t der organischen Bodensubstanz durch eine Kaltwasser-Extraktion und der spektroskopischen Eigenschaften untersucht.
Fazit: Reduzierte und konservierende Bodenbearbeitung modifiziert die Organische Bodensubstanz, die Leistung sowie die funktionelle und strukturelle DiversitÀt von Bodenmikroorganismen-Gemeinschaften
Bearing the Cost of Stored Carbon Leakage
Carbon capture and sequestration (CCS) is considered a key technology for stabilizing climate change. However, leakage of CO2 from stored carbon can potentially undermine the value of carbon storage as a mitigation option. Thus, monitoring and verifiability of CO2 storage should be encouraged through policy provisions such as accounting and pricing of leaked emissions. Here we assess different institutional and economic mechanisms for accounting for carbon leakage. Using an integrated assessment model we quantify the impacts on the climate, the economy and the mitigation strategies. Results show that carbon leakage can reduce the share of fossil based CCS by up to 35%, if it is controlled and correctly priced. Biomass based CCS is less affected. Accounting for leakage leads to an increase of climate policy costs of up to 0.4 percentage points due to increased emissions
Scaling theory of transport in complex networks
Transport is an important function in many network systems and understanding
its behavior on biological, social, and technological networks is crucial for a
wide range of applications. However, it is a property that is not
well-understood in these systems and this is probably due to the lack of a
general theoretical framework. Here, based on the finding that renormalization
can be applied to bio-networks, we develop a scaling theory of transport in
self-similar networks. We demonstrate the networks invariance under length
scale renormalization and we show that the problem of transport can be
characterized in terms of a set of critical exponents. The scaling theory
allows us to determine the influence of the modular structure on transport. We
also generalize our theory by presenting and verifying scaling arguments for
the dependence of transport on microscopic features, such as the degree of the
nodes and the distance between them. Using transport concepts such as diffusion
and resistance we exploit this invariance and we are able to explain, based on
the topology of the network, recent experimental results on the broad flow
distribution in metabolic networks.Comment: 8 pages, 6 figure
The Charging Structure for the Great Barrier Reef - A review of willingness to pay
The Great Barrier Reef Marine Park Authority (GBRMPA or the Reef Authority) is currently conducting a comprehensive review of the charging structure for the use of the Great Barrier Reef (GBR) Marine Park with a view to implement potential changes from 1 July 2023
<i>In situ</i> investigation of controlled polymorphism in mechanochemistry at elevated temperatureâ
Mechanochemistry routinely provides solid forms (polymorphs) that are difficult to obtain by conventional solution-based methods, making it an exciting tool for crystal engineering. However, we are far from identifying the full scope of mechanochemical strategies available to access new and potentially useful solid forms. Using the model organic cocrystal system of nicotinamide (NA) and pimelic acid (PA), we demonstrate with variable temperature ball milling that ball milling seemingly decreases the temperature needed to induce polymorph conversion. Whereas Form I of the NA:PA cocrystal transforms into Form II at 90 °C under equilibrium conditions, the same transition occurs as low as 65 °C during ball milling: a ca 25 °C reduction of the transition temperature. Our results indicate that mechanical energy provides a powerful control parameter to access new solid forms under more readily accessible conditions. We expect this âthermo-mechanicalâ approach for driving polymorphic transformations to become an important tool for polymorph screening and manufacturing
Exotic magnetism in the alkali sesquoxides Rb4O6 and Cs4O6
Among the various alkali oxides the sesquioxides Rb4O6 and Cs4O6 are of
special interest. Electronic structure calculations using the local
spin-density approximation predicted that Rb4O6 should be a half-metallic
ferromagnet, which was later contradicted when an experimental investigation of
the temperature dependent magnetization of Rb4O6 showed a low-temperature
magnetic transition and differences between zero-field-cooled (ZFC) and
field-cooled (FC) measurements. Such behavior is known from spin glasses and
frustrated systems. Rb4O6 and Cs4O6 comprise two different types of dioxygen
anions, the hyperoxide and the peroxide anions. The nonmagnetic peroxide anions
do not contain unpaired electrons while the hyperoxide anions contain unpaired
electrons in antibonding pi*-orbitals. High electron localization (narrow
bands) suggests that electronic correlations are of major importance in these
open shell p-electron systems. Correlations and charge ordering due to the
mixed valency render p-electron-based anionogenic magnetic order possible in
the sesquioxides. In this work we present an experimental comparison of Rb4O6
and the related Cs4O6. The crystal structures are verified using powder x-ray
diffraction. The mixed valency of both compounds is confirmed using Raman
spectroscopy, and time-dependent magnetization experiments indicate that both
compounds show magnetic frustration, a feature only previously known from d-
and f-electron systems
Genomic analysis of dominance effects on milk production and conformation traits in Fleckvieh cattle
Background
Estimates of dominance variance in dairy cattle based on pedigree data vary considerably across traits and amount to up to 50% of the total genetic variance for conformation traits and up to 43% for milk production traits. Using bovine SNP (single nucleotide polymorphism) genotypes, dominance variance can be estimated both at the marker level and at the animal level using genomic dominance effect relationship matrices. Yield deviations of high-density genotyped Fleckvieh cows were used to assess cross-validation accuracy of genomic predictions with additive and dominance models. The potential use of dominance variance in planned matings was also investigated.
Results
Variance components of nine milk production and conformation traits were estimated with additive and dominance models using yield deviations of 1996 Fleckvieh cows and ranged from 3.3% to 50.5% of the total genetic variance. REML and Gibbs sampling estimates showed good concordance. Although standard errors of estimates of dominance variance were rather large, estimates of dominance variance for milk, fat and protein yields, somatic cell score and milkability were significantly different from 0. Cross-validation accuracy of predicted breeding values was higher with genomic models than with the pedigree model. Inclusion of dominance effects did not increase the accuracy of the predicted breeding and total genetic values. Additive and dominance SNP effects for milk yield and protein yield were estimated with a BLUP (best linear unbiased prediction) model and used to calculate expectations of breeding values and total genetic values for putative offspring. Selection on total genetic value instead of breeding value would result in a larger expected total genetic superiority in progeny, i.e. 14.8% for milk yield and 27.8% for protein yield and reduce the expected additive genetic gain only by 4.5% for milk yield and 2.6% for protein yield.
Conclusions
Estimated dominance variance was substantial for most of the analyzed traits. Due to small dominance effect relationships between cows, predictions of individual dominance deviations were very inaccurate and including dominance in the model did not improve prediction accuracy in the cross-validation study. Exploitation of dominance variance in assortative matings was promising and did not appear to severely compromise additive genetic gain
Cognitive predictors of reactive and proactive aggression in a forensic sample: A comparison with a non-clinical sample
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