Aktivität, Populationsdynamik und Diversität Methan oxidierender Bakterien im Reisfeld

Die Methan oxidierenden Bakterien können durch die Umsetzung von Methan die Emission dieses Treibhausgases aus gefluteten Reisfeldern deutlich verringern. Um nähere Erkenntnisse über die Aktivität und Populationsstruktur der Methanotrophen im Reisfeld zu erhalten, wurden Mikrokosmos- und Feldexperimente durchgeführt. Die Ergebnisse dieser beiden Systeme waren qualitativ gut vergleichbar. Der positive Einfluss der Reiswurzel auf die Methanotrophen war durch die Kompartimentierung im Mikrokosmos deutlicher nachzuweisen als im Feld. Die in­situ Methanoxidation hatte sowohl im Feld als auch im Mikrokosmos nur während der ersten Wochen der Vegetationsperiode Einfluss auf die Methanemissionen. Dagegen blieben die Initialraten in Messungen der potentiellen Methanoxidation in Bodensuspensionen auch nach Abnahme der Aktivität in-situ anhaltend hoch. Dies wies auf eine in-situ Limitierung der Methan oxidierenden Bakterien hin, die auf einen Mangel an leichtverfügbaren Stickstoffverbindungen zurückgeführt werden konnte. Die Zellzahl der Methanotrophen nahm während des Wachstums der Reispflanze besonders in Rhizoplane und Homogenisat der Wurzel, aber auch im durchwurzelten Boden zu. Im Mikrokosmos konnte eine in-situ Dominanz der Typ II Methanotrophen in allen Kompartimenten und über die gesamte Vegetationsperiode nachgewiesen werden. Die Zahl der Typ I Methanotrophen erreichte nur in der Rhizoplane Anteile von bis zu 2/3 der Gesamtpopulation. Die Wurzel ist demnach nicht nur für den Erhalt der Grösse, sondern auch der Diversität der Population wichtig. Im Feldversuch wurden beide Familien in vergleichbaren Zellzahlen nachgewiesen. Die Populationsstruktur wies trotz des Wachstums der Methanotrophen keine ausgeprägten Änderungen auf. Für Typ II wurden beide Gattungen (Methylosinus und Methylocystis) nachgewiesen, während für Typ I nur zur Gattung Methylo-bacter ähnliche Sequenzen gefunden wurden. Die Dominanz von Methylobacter könnte auf einen Selektionsvorteil gegenüber anderen Typ I Gattungen zurück-zuführen sein. Da Reisfelder periodisch trocken gelegt werden, erhalten diejenigen Bodenbakterien einen Vorteil, die Trocknungsstress überstehen können. Methylo-bacter ist die einzige Typ I Gattung mit einem trocknungsresistenten Dauersta-dium und auch beide nachgewiesenen Typ II Gattungen bilden entsprechende Dauerstadien. Diese Fähigkeit ermöglichte es ihnen, im Reisfeld zu überdauern und verdeutlichte so die selektiven Auswirkungen der Physiologie auf die Populationsstruktur der Methan oxidierenden Bakterien

Nonmarine Ostracoda as proxies in (geo-)archaeology: a review

Abstract Ostracods as bioindicators are extremely useful for reconstructing palaeoenvironment and palaeoclimate and can also indicate the provenance of sediments and materials, for example, in studies on ancient commercial networks. Ostracods are small crustaceans that live in almost all aquatic habitats, both natural and man-made. Due to their calcitic carapace, they have high fossilization potential, and their use in geoarchaeology has been steadily increasing during the last decades. Their small size needs mean that only small volumes of sediment samples are needed, and species-specific ecological tolerances and preferences allow detailed palaeoenvironmental reconstructions. Typical methods of their application are palaeoecological analyses of associations based on ecological information and taphonomy, morphometric variability and stable isotope and chemistry analyses of their shells. The present paper aims to present an overview of applications of non-marine ostracods in (geo-)archaeological research, recommending sampling and analytical techniques for addressing archaeological research questions on palaeoclimate, habitat and landscape changes, water availability and quality, land use and other anthropogenic impacts, the provenance of materials and commercial networks to promote the application of Ostracoda in geoarchaeology/environmental archaeology.1 Introduction 2 Applications 2.1 short history of ostracod‐based palaeoenvironmental reconstructions 2.2 Palaeoclimate and palaeoenvironmental studies on continental archaeological sites 2.2.1 General palaeoenvironment/landscape reconstructions 2.2.2 Salinity 2.2.3 Temperature 2.2.4 Radiocarbon dating 2.3 Landscape changes by human activity 2.4 Water use and water works 2.5 Provenance studies 3 Methods for sampling and lab analyses 4 Conclusion

Two-component radiation model of the sonoluminescing bubble

Based on the experimental data from Weninger, Putterman & Barber, Phys. Rev. (E), 54, R2205 (1996), we offer an alternative interpretation of their experimetal results. A model of sonoluminescing bubble which proposes that the electromagnetic radiation originates from two sources: the isotropic black body or bramsstrahlung emitting core and dipole radiation-emitting shell of accelerated electrons driven by the liquid-bubble interface is outlined.Comment: 5 pages Revtex, submitted to Phys. Rev.

Supply Current Diagnosis in VLSI

This paper presents a technique based upon the power supply current signature (cd) which allows for the testing of mixed-signal systems, in situ. Through experiments with a microprocessor, the cd is shown to contain important information concerning the operational status of the system which may be easily extracted using approaches based on statistical signal detection theory. The fault-detection performance of these techniques is compared to that achieved through auto-regressive modeling of the cd

Nonradiative Electronic Deexcitation Time Scales in Metal Clusters

The life-times due to Auger-electron emission for a hole on a deep electronic shell of neutral and charged sodium clusters are studied for different sizes. We consider spherical clusters and calculate the Auger-transition probabilities using the energy levels and wave functions calculated in the Local-Density-Approximation (LDA). We obtain that Auger emission processes are energetically not allowed for neutral and positively charged sodium clusters. In general, the Auger probabilities in small Na$_N^-$ clusters are remarkably different from the atomic ones and exhibit a rich size dependence. The Auger decay times of most of the cluster sizes studied are orders of magnitude larger than in atoms and might be comparable with typical fragmentation times.Comment: 11 pages, 4 figures. Accepted for publication in Phys. Rev.

СУТНІСТЬ ТА ПРОЦЕС ФОРМУВАННЯ ІНТЕГРОВАНИХ МАРКЕТИНГОВИХ КОМУНІКАЦІЙ

Проаналізовано сутність, характеристика, принципи інтегрованих комунікацій та розкрито особливості процесу їх формування на підприємствах України.; The essence, characteristics and principles of integrated communications are analyzed. The peculiarities of the process of their formation on the enterprises are discovered

Gauge Theories with Cayley-Klein SO(2;j)SO(2;j) and SO(3;j)SO(3;j) Gauge Groups

Gauge theories with the orthogonal Cayley-Klein gauge groups $SO(2;j)$ and $SO(3;{\bf j})$ are regarded. For nilpotent values of the contraction parameters ${\bf j}$ these groups are isomorphic to the non-semisimple Euclid, Newton, Galilei groups and corresponding matter spaces are fiber spaces with degenerate metrics. It is shown that the contracted gauge field theories describe the same set of fields and particle mass as $SO(2), SO(3)$ gauge theories, if Lagrangians in the base and in the fibers all are taken into account. Such theories based on non-semisimple contracted group provide more simple field interactions as compared with the initial ones.Comment: 14 pages, 5 figure

Mechanisms for Stable Sonoluminescence

A gas bubble trapped in water by an oscillating acoustic field is expected to either shrink or grow on a diffusive timescale, depending on the forcing strength and the bubble size. At high ambient gas concentration this has long been observed in experiments. However, recent sonoluminescence experiments show that in certain circumstances when the ambient gas concentration is low the bubble can be stable for days. This paper presents mechanisms leading to stability which predict parameter dependences in agreement with the sonoluminescence experiments.Comment: 4 pages, 3 figures on request (2 as .ps files

Stress-induced activation of the proline biosynthetic pathway in Bacillus subtilis:A population-wide and single-cell study of the osmotically controlled proHJ promoter

Bacillus subtilis, in its natural habitat, is regularly exposed to rapid changes in the osmolarity of its surrounding. As its primary survival strategy, it accumulates large amounts of the compatible solute proline by activating the de novo proline biosynthesis pathway and exploiting the glutamate pools. This osmotically-induced biosynthesis requires activation of a SigA-type promoter that drives the expression of the proHJ operon. Population-wide studies have shown that the activity of the proHJ promoter correlates with the increased osmotic pressure of the environment. Therefore, the activation of the proHJ transcription should be an adequate measure of the adaptation to osmotic stress through proline synthesis in the absence of other osmoprotectants. In this study, we investigate the kinetics of the proHJ promoter activation and the early adaptation to mild osmotic upshift at the single-cell level. Under these conditions, we observed a switching point and heterogeneous proline biosynthesis gene expression, where the subpopulation of cells showing active proHJ transcription is able to continuously divide, and those unresponsive to osmotic stress remain dormant. Additionally, we demonstrate that bactericidal antibiotics significantly upregulate proHJ transcription in the absence of externally imposed osmotic pressure, suggesting that the osmotically-controlled proline biosynthesis pathway is also involved in the antibiotic-mediated stress response