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Application of metabolomics to plant genotype discrimination using statistics and machine learning
(2003)
Stomatal cell biology
(2003)
Offenlandmanagement durch kontrolliertes Brennen : ein Beitrag aus sozioökonomischer Perspektive
(2003)
We study numerically the behavior of the autocorrelation function (ACF) and the power spectrum of spiral attractors without and in the presence of noise. It is shown that the ACF decays exponentially and has two different time scales. The rate of the ACF decrease is defined by the amplitude fluctuations on small time intervals, i.e., when tau < tau(cor), and by the effective diffusion coefficient of the instantantaneous phase on large time intervals. it is also demonstrated that the ACF in the Poincare map also decreases according to the exponential law exp(-lambda(+)k), where lambda(+) is the positive Lyapunov exponent. The obtained results are compared with the theory of fluctuations for the Van der Pol oscillator
The aim of this study was to establish a long-term culture. system for rat colon epithelia isolaled by incubating a 4-cm-long rat colon segment cut longitudinally with all ethylenediaminetetraacetic acid [disodium salt]- containing buffer, taken up in conditioned medium from the normal rat kidney fibroblast cell line NRK (i.e., the supernatant Of pure NRK cultures), directly plated on mitomycin C-treated NRK cells and subcultured with conditioned medium from NRK cells. Cells started to migrate out of the crypts shortly after plating them on NRK feeder layers. Some of the crypts fell apart during the isolation procedure. whereas the vast majority of them did it within I to 2 Ill after plating. The cells proliferated extremely slowly but continuously over a period of 4 mo and were epithelial because they expressed cytokeratin 19 and were stained by crystal violet at pH 2.8. In conclusion, the experimental system described ill this study allows to maintain rat colon epithelial cells for up to 4 mo in culture and can be used to Study the effects of a variety of tumor-modulating factors on growth and gene expression of normal colon epithelial cells in vitro
Folgt man der geläufigen "Individualisierungsthese" und ihrer jugendspezifischen Wendung, dann müssten die in dieser These unterstellten Individualisierungsprozesse auch in der Beteiligung der Jugendlichen am vereinsorganisierten Sport in Erscheinung treten. Vier Annahmen lassen sich plausibel begründen: (1) Jugendlichen ziehen sich auch Sportvereinen und ihren Mitgliedschaftsverbindlichkeiten zunehmend zurück. (2) Anstelle dauerhafter kommen nur noch kurzfristige, explorative Vereinsmitgliedschaften zustande. (3) Mitgliederbindungen erodieren. (4) Jugendliche engagieren sich in Sportvereinen kaum mehr freiwillig. Die in dem Betrag referierten empirischen Befunde können alllerdings keine dieser Annahmen stützen. Die einfache Gleichung, wonach eine fortschreitende Individualisierung zu einer Erosion von Mitgliedschaftsbeziehungen und freiwilligem Engagement führe, scheint zumindest für die Beziehungen der Jugendlichen zu sportverinen nicht aufzugehen.
Wieder zu lesen
(2003)
Sportpsychologie
(2003)
The unification of X-ray and radio selected BL Lacs has been an outstanding problem in the blazar research in the past years. Recent investigations have shown that the gap between the two classes can be filled with intermediate objects and that apparently all differences can be explained by mutual shifts of the peak frequencies of the synchrotron and inverse Compton component of the emission. We study the consequences of this scheme using a new sample of X-ray selected BL Lac objects comprising 104 objects with z<0.9 and a mean redshift bar {z} = 0.34. 77 BL Lacs, of which the redshift could be determined for 64 (83%) objects, form a complete sample. The new data could not confirm our earlier result, drawn from a subsample, that the negative evolution vanishes below a synchrotron peak frequency log nupeak = 16.5. The complete sample shows negative evolution at the 2sigma level (< Ve/Va > = 0.42 +/- 0.04). We conclude that the observed properties of the HRX BL Lac sample show typical behaviour for X-ray selected BL Lacs. They support an evolutionary model, in which flat-spectrum radio quasars (FSRQ) with high energetic jets evolve towards low frequency peaked (mostly radio-selected) BL Lac objects and later on to high frequency peaked (mostly X-ray selected) BL Lacs.
Der vergessene Nestor
(2003)
Mixotrophy in the Antarctic phytoflagellate, Pyramimonas gelidicola (Chlorophyta: Prasinophyta)
(2003)
Grazing by the planktonic, phytoflagellate, Pyramimonas gelidicola McFadden (Chlorophyta: Prasinophyta), and heterotrophic nanoflagellates (HNAN) in meromictic, saline Ace Lake in the Vestfold Hills, Eastern Antarctica, was investigated in the austral summers of 1997 and 1999. Up to 47% of the P. gelidicola population ingested fluorescently labelled prey (FLP). Ingestion rates varied with depth. In January 1997 and November 1999, maximum P. gelidicola ingestion rates of 6.95 and 0.79 FLP;cell-1;h-1, respectively, were measured at the chemocline (6-8 m) where a deep chlorophyll maximum composed of phototrophic nanoflagellates (PNAN DCM), predominantly P. gelidicola, persisted all year. During the summers of 1997 and 1999, the grazing P. gelidicola community removed between 0.4 and approximately 16% of in situ bacterial biomass, equivalent to between 4 and >100% of in situ bacterial production. Due to their higher abundance, the community clearance rates of HNAN in Ace Lake generally exceeded those of P. gelidicola but HNAN removed approximately only 3 to 4% of bacterial biomass, equivalent to between 28 and 32% of bacterial production. P. gelidicola growth rates were highest at the PNAN DCM concomitant with the highest ingestion rates. It is estimated that during the summer P. gelidicola can derive up to 30% of their daily carbon requirements from bacterivory at the PNAN DCM. This study confirms mixotrophy as an important strategy by which planktonic organisms can survive in extreme, polar, lacustrine ecosystems.
South Africa's endemic Knysna seahorse, Hippocampus capensis Boulenger 1900, is a rare example of a marine fish listed as Endangered by the IUCN because of its limited range and habitat vulnerability. It is restricted to four estuaries on the southern coast of South Africa. This study reports on its biology in the Knysna and Swartvlei estuaries, both of which are experiencing heavy coastal development. We found that H. capensis was distributed heterogeneously throughout the Knysna Estuary, with a mean density of 0.0089 m-2 and an estimated total population of 89 000 seahorses (95% confidence interval: 30 000 to 148 000). H. capensis was found most frequently in low density vegetation stands ( 20% cover) and grasping Zostera capensis. Seahorse density was not otherwise correlated with habitat type or depth. The size of the area in which any particular seahorse was resighted did not differ between males and females. Adult sex ratios were skewed in most transects, with more males than females, but were even on a 10 m by 10 m focal study grid. Only three juveniles were sighted during the study. Both sexes were reproductively active but no greeting or courtship behaviours were observed. Males on the focal study grid were longer than females, and had shorter heads and longer tails, but were similar in colouration and skin filamentation. The level of threat to H. capensis and our limited knowledge of its biology mean that further scientific study is urgently needed to assist in developing sound management practices.
In recent years most studies of the benthic microbial food web have either been descriptive or were restricted to the measurement of within sediment process rates. Little is known about benthic-pelagic coupling processes such as recruitment. We, therefore, developed an ex situ core incubation procedure to quantify the potential for microbial recruitment from the benthos to the pelagic in an acidic mining lake, Mining Lake 111 (ML 111; pH 2.6), in eastern Germany. Our data suggest that considerable zooplankton recruitment from the benthos takes place. Heliozoan and rhizopod recruitment in both summer and winter sediment cores was highest when they were incubated at 20°C. Maximum heliozoan recruitment was 23 (± 9 s.e.) individuals cm-2 d-1 (40% initial standing stock daily) in the winter 20°C incubation. Maximum rhizopod recruitment was 6 (± 2 s.e.) individuals cm-2 d-1 in the summer 20°C incubation. Little or no recruitment was apparent for either taxa when winter cores were incubated at 5°C, implying a temperature cue. Conversely, the rotifer, Cephalodella hoodi, exhibited a maximum recruitment of 6 (± 2 s.e.) individuals cm-2 d-1 during the winter 5°C incubation, representing 30% of initial standing stock daily, but little recruitment when incubated at 20°C. Cephalodella may have responded to an increased winter benthic food supply; in situ winter Chl a concentrations in the benthos were 3.4 times higher than those in the summer. The importance of this was reinforced by the poor pelagic food supply available in ML 111. In situ, Heliozoa, rhizopods and Cephalodella were first observed in the epilimnion of ML 111 in spring or early summer, suggesting active or passive recruitment following lateral transport from littoral sediments. Benthic-pelagic coupling via recruitment is potentially important in understanding the pelagic food web in ML 111 and warrants further investigation in this and other aquatic environments.
Streik in der Diakonie ?
(2003)
We modeled the two most extreme highstands of Lake Naivasha during the last 175 k.y. to estimate potential precipitation/ evaporation changes in this basin. In a first step, the bathymetry of the paleolakes at f135 and 9 k.y. BP was reconstructed from sediment cores and surface outcrops. Second, we modeled the paleohydrologic budget during the highstands using a simplified coupled energy mass-balance model. Our results show that the hydrologic and hence the climate conditions at f135 and 9 k.y. BP were similar, but significantly different from today. The main difference is a f15% higher value in precipitation compared to the present. An adaptation and migration of vegetation in the cause of climate changes would result in a f30% increase in precipitation. The most likely cause for such a wetter climate at f135 and 9 k.y. BP is a more intense intertropical convergence and increased precipitation in East Africa.
"Sammelgebiet DDR"
(2003)
Summary Using five different steps, ;-Galactosidase has been purified from kidney beans to apparent electrophoretic homogeniety with approximately 90-fold purificationwith a specific activity of 281 units mg;1 protein. A single bandwas observed in native PAGE. Activity staining of the native gel with 5-bromo4-chloro 3-indoxyl ;-D-galactopyranoside (X-Gal) at pH 4.0 also produceda single band. Analytical gel filtration in Superdex G-75 revealed the molecularmass of the native protein to be approximately 75 kD. 10 percnt; SDS-PAGE under reducingconditions showed two subunits of molecular masses, 45 and 30 kD, respectively.Hence, ;-galactosidase from kidney beans is a heterodimer. A typical proteinprofile with ;max at 280 nm was observed and A280/A260ratio was 1.52. The N-terminal sequence of the 45 kD band showed 86 percnt; sequencehomology with an Arabidopsis thaliana and 85 percnt; with Lycopersiconesculentum putative ;-galactosidase sequences. The Electrospray MassSpectrometric analysis of this band also revealed a peptide fragment that had90 percnt; sequence homology with an Arabidopsis thaliana putative ;- galactosidasesequence. The N-terminal sequencing of the 30 kD band as well as mass spectrometricanalysis both by MALDI- TOF and ES MS revealed certain sequences that matchedwith phytohemagglutinin of kidney beans. The optimum pH of the enzyme was 4.0and it hydrolysed o- and p-nitrophenyl ;-D galactopyranosidewith a Km value of 0.63 mmol/L and 0.74 mmol/L, respectively.The energy of activation calculated from the Arrhenius equation was 14.8 kcal/molenzyme site. The enzyme was found to be comparatively thermostable showing maximumactivity at 67 °C. Thermal denaturation of the enzyme at 65 °C obeyssingle exponential decay with first order-rate constant 0.105 min;1.Galactose, a hydrolytic product of this enzyme was a competitive inhibitor witha Ki of 2.7 mmol/L.
Literaten und Soldaten
(2003)
Naturschutzplanung
(2003)
Zwischen Gemeinschaftsorientierung und Selbstverwirklichung : Motive zu freiwilligem Engagement
(2003)
Neue alte Weltordnung
(2003)
Stemming the torrent : expression and control in Victorian discourses on emotion, 1830 - 1872
(2003)
Becketts Fußzeug
(2003)
Rivers form the most important natural corridors through the landscape. Certain plant species grow mainly or exclusively in these corridors as it has been observed for about 150 years in Central European lowlands. However, these species do not form a homogenous group in terms of biogeography, site requirements, life form, or any other feature this distribution pattern. Accordingly, first, we give a review of the various hypotheses which have been proposed to explain the river corridor distribution pattern. This includes (1) river corridors acting as routes of migration or invasion, (2) floodplain-specific disturbance providing open sites, (3) temporary anoxic conditions during floods, (4) deviating meso-climatic conditions, (5) specific substrate and nutrient supply, and (6) water supply. In particular, the above hypotheses (2-5) imply that river corridor plants may be well-adapted to specific stress and regeneration conditions in floodplains while other species may be not. This may lead to reduced competition in river corridors. We suggest this mechanism to constitute actual benefits for river corridor plants. Secondly, we present a simple model of multi-species population dynamics to show, that our competition-related framework is, in principle, able to explain river corridor plant species distribution patterns. As, however, none of the above hypotheses (1-6) have been tested experimentally we thirdly present a currently running experimental study on the river corridor plant Juncus atratus (black rush) in north- eastern Germany. We emphasize that much more experimental evidence must be gained on population ecology and meta- population dynamics to understand the distribution patterns of river corridor plants.