Robust Weak Ergodicity And Stable Ergodicity

In this paper, we define robust weak ergodicity and study the relation between robust weak ergodicity and stable ergodicity for conservative partially hyperbolic systems. We prove that a C^r(r > 1) conservative partially hyperbolic diffeomorphism is stably ergodic if it is robustly weakly ergodic and has positive (or negative) central exponents on a positive measure set. Furthermore, if the condition of robust weak ergodicity is replaced by weak ergodicity, then the diffeomophism is an almost stably ergodic system. Additionally, we show in dimension three, a C^r(r > 1) conservative partially hyperbolic diffeomorphism can be approximated by stably ergodic systems if it is robustly weakly ergodic and robustly has non-zero central exponents.     

Beitrag zur elementaren Integration nichtlinearer Transportgleichungen in der Isotopentrennung,Teil I

Eine umfangreiche Klasse von Isotopentrenverfahren lāβ sich einheitlich durch die Cohenschen Tranportgleichungen beschreiben. Im einfachsten Fall handelt es sich um ein System von zwei partiellen Differentialgleichungen erster Ordnung vom hyperbolischen Typ. Dieses nichtlineare System wird durch geeignete Substitution auf eine lineare Differentialgleichung zweiter Ordnung zurāckgeführt. Im Anschluβ daran werden Problemstellungen abgegrenzt, bei denen nach Reduktion auβer der Differentialgleichung auch die Rand- und Anfangsbedingungen linear ausfallen.     

Erfahrungen bei der simultanen Bestimmung von Gesamtstickstoff und 15N durch Kopplung von “Dumas”-Stickstoffbestimmungsgeräten mit dem NOI-6

Ziel der Arbeiten war die Untersuchung von Systemvarianten zur simultanen Bestimmung von Gesamtstickstoff und ¹⁵N in organischem Probematerial für problemorientierte Anwendungen der ¹⁵N-Tracertchnik auf Gebieten der Landwirtschaftsforschung, Biologie, Medizin und Umweltforschung unter Benutzung des emissionsspektroskopischen Analysators NOI-6 zur ¹⁵N-Analyse. Von der Vielzahl der prinzipiell verfügbaren kommerziellen Stickstoffanalysatoren konnten folgende Geräte zur Kopplung mit dem NOI-6 eingesetzt werden:

• —FP 228 der Fa. LECO,

• —CHN 89.00 der Fa. DANI,

• —NA 1500 der Fa. Carlo Erba und

• —Roboprep von der Fa. Europa Scientific.

Obwohl das Grundprinzip aller kommerziellen “Dumas”-Stickstoffbestimmungsgeräte das gleiche ist, gibt es im Detail, der Konzeption und Ausführung der Geräte beachtliche Unterschiede. Zur simultanen Bestimmung von Gesamtstickstoff und ¹⁵N wurden die angegebenen Geräte – FP 228, CHN 89.00, NA 1500 und Roboprep mit dem NOI-6 gekoppelt. Es lassen sich prinzipiell alle getesteten Gerätevarianten für die simultane Bestimmung von Gesamtstickstoff und ¹⁵N verwenden. Wie Detailuntersuchungen, u.a. des Memory-Effektes oder die Einflüsse des Gesamtstickstoffs auf die Messung der ¹⁵N-Konzentration zeigen, sind in jedem Falle sorgfältige Kalibrierungen erforderlich.

Aim of the work was the examination of system-versions for the simultaneous determination of total Nitrogen and N15 in organic sample-material for problem orientated use of the N15 Tracertechnique in the fields of agricultural research, biology, medicine and environmental research by use of the emission spectroscopic NOI-6 Analyzer. There are a lot of commercially available Nitrogen-Analyzers. The following Nitrogen-Analyzers were tested and coupled with the NOI-6 N15 Analyzer-System:

• —FP 228 LECO,

• —CHN 89.00 DANI,

• —NA 1500 Carlo Erba and

• —Roboprep Europa Scientific.

The fundamental principle of all Nitrogen-Analyzers is the same. There are notable differences in details, conceptions and design of different devices. For the simultaneous determination of total nitrogen and N15 were coupled the pretended “Nitrogen Analyzers” FP 228, CHN 89.00, NA 1500 and Roboprep with the NOI-6 Analyzer. Generally it is possible to use all the tested equipment-versions for the simultaneous determination of total Nitrogen and N15. Extensive examinations -also of the “Memory-effect” and the influence of the total Nitrogen amount to the measurement of the N-15 concentration -show the necessity of a careful calibration in each case.     

Untersuchungen zur Isotopensignatur von Methan und Kohlendioxid aus biogenen Gasen unterschiedlicher Quellen

Abstract

The isotopic compositions of biogenic carbon dioxide and methane from different sites were investigated. The δ¹³C values of methane vary mainly between ?55‰ and ?75‰ whereas δ¹³C values of carbon dioxide were found from about + 11‰ to ?23‰. Especially the latter ones are not so typical for microbial gases. The different sites don't vary over the whole scales but form certain groups. Secondary effects like diffusion change the δ values of both components in an even more negative direction, while oxidation processes near the surface result in more positive δ¹³C values for methane and very negative δ¹³C values for carbon dioxide.     

Determination of the Parameter Ratio H0 2/K of Closed Thermal Diffusion Columns for Polynary Isotopic Mixtures

For the experimental determination of the H₀ ²/K ratio of the constants for prototype thermal diffusion columns from initial state mole fraction measurements there was a lack of sufficiently exact simple evaluation methods for polynary isotopic mixtures.

The investigation of mole fraction changes at closed ends obtained by numerical integration of the corresponding system of second order partial differential equations resulted in a concept of approximation which allows to utilize approximative analytical solutions originally developed for binary isotopic mixtures.

In the approximation the initial mole fractions are indirectly represented by the mean mass number of the initial mixture.

Thus, the measured mole fraction changes can be attributed to the difference between the actual mass number of the components and the mean mass number of the enclosed mixture. By simple regression analysis a partial derivative can be obtained which can be attributed to the approximative analytical solutions for binary mixtures.     

Soil matrix tracer contamination and canopy recycling did not impair 13CO2 plant–soil pulse labelling experiments

When conducting ¹³CO₂ plant–soil pulse labelling experiments, tracer material might cause unwanted side effects which potentially affect δ¹³C measurements of soil respiration (δ¹³C_SR) and the subsequent data interpretation. First, when the soil matrix is not isolated from the atmosphere, contamination of the soil matrix with tracer material occurs leading to a physical back-diffusion from soil pores. Second, when using canopy chambers continuously, ¹³CO₂ is permanently re-introduced into the atmosphere due to leaf respiration which then aids re-assimilation of tracer material by the canopy. Accordingly, two climate chamber experiments on European beech saplings (Fagus sylvatica L.) were conducted to evaluate the influence of soil matrix ¹³CO₂ contamination and canopy recycling on soil ¹³CO₂ efflux during ¹³CO₂ plant–soil pulse labelling experiments. For this purpose, a combined soil/canopy chamber system was developed which separates soil and canopy compartments in order to (a) prevent diffusion of ¹³C tracer into the soil chamber during a ¹³CO₂ canopy pulse labelling and (b) study stable isotope processes in soil and canopy individually and independently. In combination with laser spectrometry measuring CO₂ isotopologue mixing ratios at a rate of 1 Hz, we were able to measure δ¹³C in canopy and soil at very high temporal resolution. For the soil matrix contamination experiment, ¹³CO₂ was applied to bare soil, canopy only or, simultaneously, to soil and canopy of the beech trees. The obtained δ¹³C_SR fluxes from the different treatments were then compared with respect to label re-appearance, first peak time and magnitude. By determining the δ¹³C_SR decay of physical ¹³CO₂ back-diffusion from bare soils (contamination), it was possible to separate biological and physical components in δ¹³C_SR of a combined flux of both. A second pulse labelling experiment, with chambers permanently enclosing the canopy, revealed that ¹³CO₂ recycling at canopy level had no effect on δ¹³C_SR dynamics.     

Stable isotopes determination in some Romanian fruit juices

The characterisation of 45 Romanian single-strength fruit juices (apples, pears, plums and grapes) collected from different Transylvanian areas by means of stable isotope approach are presented and discussed in this study. We measured ²H/¹H, ¹⁸O/¹⁶O ratios from water juice and ¹³C/¹²C from pulp and compared these results with those already reported in the literature for single-strength juices, in order to see how the geographical and climatic conditions of Transylvania and the meteorological peculiarities of the year 2010 influence the isotopic composition of the investigated fruit juices. The δ¹³C mean values that we found for apple pulp picked up from different Transylvanian areas show slight differences, probably due to the environmental conditions of the plants. No significant correlation either between the variety of apple or the geographical origin and δ¹³C value was established.     

Isotope variations of hydrogen,carbon and nitrogen in florae from the Schirmacher Oasis,East Antarctica

Comparative biochemical and isotope-chemical investigations of cosmopolitical plants open up ways of obtaining parameters from different parts of the Earth which are characterised by variations in the habitat due to different environments. As an Antarctic oasis, the Schirmacher Oasis disposes of adequate favourable ecological conditions for the growth of lower plants.

In the present paper, results of isotope studies of lichens, mosses and algae of the Schirmacher Oasis are given and peculiarities of the habitats which influence the isotope contents of the plants are discussed.     

The Impact of Ozone on the 15N Incorporation and Nitrogen Assimilation of Wheat and Maize

Abstract

Young wheat (C3) and maize (C4) plants were exposed to near-ambient concentrations of ozone in open-top chambers in order to investigate the possible effects of ozone on nitrogen metabolism. Nitrogen was supplied to the plants by adding ¹⁵N-labelled tracer substances via the soil substrate. Enzyme activities (NADH nitrate reductase, nitrite reductase, glutamine synthetase and NADH glutamate dehydrogenase) and the incorporation of ¹⁵N were determined.

The findings show that nitrogen metabolism was affected by O₃, however, there were distinct differences between the two species. In plants treated with O₃, NADH nitrate reductase activity in maize leaves was reduced, while NR activity in wheat leaves only slightly declined. Only minor changes were observed with respect to the activities of nitrite reductase, glutamine synthetase and NADH glutamate dehydrogenase.

Feeding experiments using ¹⁵NO₃ ^? showed that the incorporation of nitrate nitrogen in wheat plants exposed to ozone remains virtually unchanged, whereas in maize plants reduced incorporation rates were observed for nitrate nitrogen. The incorporation of ammonium nitrogen was distinctly increased in wheat and maize by the impact of ozone.

When investigating pigment contents, reduced levels of chlorophyll a and b and carotenoids were observed, whereas the pigment content of wheat leaves remained unchanged. These results indicate that young maize plants are more susceptible than wheat plants to short-term ozone exposure.