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Investigations of semiconductor surfaces and interfaces by X-ray grazing incidence diffraction
(2000)
Rückständige Rentenanteil
(2000)
Verfasser erörtert das Urteil des BGH vom 2000, VI ZR 300/99, nach dem für Schadensersatzansprüche auf rückständige Rentenanteile, die den Mehrbedarf des Verletzten betreffen, ohne Rücksicht auf den Rechtsgrund der vierjährige Verjährungsfrist des $ 197 BGB gilt. Verfasser merkt an, dass der BGH mit dieser Entscheidung seine Rechtsprechung zu BG $$ 197 und 208 BGB bestätige und ihr sei im Ergebnis zuzustimmen. Die Anwendung des $ 197 BGB auf Schadensersatzrenten entspreche nicht nur der gängigen Rechtsprechung, sondern finde auch breite Unterstützung in der Literatur.
Simulacrum as sub-text : fiction writing in the face of media representations of american history
(2000)
Solid varieties of semirings
(2000)
The main intention of this contribution is to discuss different nonlinear approaches to heart rate and blood pressure variability analysis for a better understanding of the cardiovascular regulation. We investigate measures of complexity which are based on symbolic dynamics, renormalised entropy and the finite time growth rates. The dual sequence method to estimate the baroreflex sensitivity and the maximal correlation method to estimate the nonlinear coupling between time series are employed for analysing bivariate data. The latter appears to be a suitable method to estimate the strength of the nonlinear coupling and the coupling direction. Heart rate and blood pressure data from clinical pilot studies and from very large clinical studies are analysed. We demonstrate that parameters from nonlinear dynamics are useful for risk stratification after myocardial infarction, for the prediction of life-threatening cardiac events even in short time series, and for modelling the relationship between heart rate and blood pressure regulation. These findings could be of importance for clinical diagnostics, in algorithms for risk stratification, and for therapeutic and preventive tools of next generation implantable cardioverter defibrillators.
Mixotrophy is a widespread phenomenon among planktonic protists. It involves the combination of autotrophy and heterotrophy in varying degrees. Many phytoflagellate species ingest bacteria as a means of obtaining nutrients for photosynthesis or for supplementing their carbon budget under light limitation. Ciliates either sequester the plastids of their algal prey or harbour endosymbiotic algae. In the saline lakes of the Vestfold Hills and in Lakes Hoare and Fryxell in the McMurdo Dry Valleys the dominant phytoflagellates ingest bacteria, and there is evidence to suggest that during the winter months they lack chlorophyll and may become entirely heterotrophic. In Lake Fryxell phagotrophic pyhtoflagellates (cryptophytes) made a significant impact on bacterial production, removing up to 13% of the bacterial biomass day-1. These cryptophytes suffered predation from Plagiocampa (a ciliate), which appears to harbour them for a significant period before digesting them. We suspect that this may be equivalent to an intermediate stage in the evolution of mixotrophy. A significant number of the planktonic ciliates in Antarctic lakes were mixotrophic. The final evolutionary end point is the situation seen in Mesodinium rubrum, which now relies entirely on its cryptophycean endosymbiont and no longer ingests food. Mesodinium is the dominant ciliate in many of the saline lakes of the Vestfold Hills, which are of marine origin. It can reach abundances in excess of 60,000l-1 in Ace Lake, This ciliate is a ubiquitous member of the marine plankton worldwide and has successfully adapted to the lacustrine environment in Antarctica. The evidence suggests that among the survival strategies seen in Antarctic lake plankton, mixotrophy plays and important role among a number of the dominant protozoan species.
The growth rates of heterotrophic nanoflagellates (HNAN), mixotrophic cryptophytes, dinoflagellates and ciliates in field assemblages from Ace Lake in the Vestfold Hills (eastern Antarctica) and Lakes Fryxell and Hoare (McMurdo Dry Valleys, western Antarctica), were determined during the austral summers of 1996/1997 and 1997/1998. The response of the nanoflagellates to temperature differed between lakes in eastern and western Antarctica. In Ace Lake the available bacterial food resources had little impact on growth rate, while temperature imposed an impact, whereas in Lake Hoare increased bacterial food resources elicited an increase in growth rate. However, the incorporation of published data from across Antarctica showed that temperature had the greater effect, but that growth is probably controlled by a suite of factors not solely related to bacterial food resources and temperature. Dinoflagellates had relatively high specific growth rates (0.0057-0.384 h(-1)), which were comparable to Antarctic lake ciliates and to dinoflagellates from warmer, lower latitude locations. Temperature did not appear to impose any significant impact on growth rates. Mixotrophic cryptophytes in Lake Hoare had lower specific growth rates than HNAN (0.0029-0.0059 h(-1) and 0.0056-0.0127 h(-1), respectively). They showed a marked seasonal variation in growth rate, which was probably related to photosynthetically active radiation under the ice at different depths in the water column. Ciliates' growth rates showed no relationship between food supply and mean cell volume, but did show a response to temperature. Specific growth rates ranged between 0.0033 and 0.150 h(-1) for heterotrophic ciliates, 0.0143 h(-1) for a mixotrophic Plagiocampa species and 0.0075 h(-1) for the entirely autotrophic ciliate, Mesodinium rubrum. The data indicated that the scope for growth among planktonic Protozoa living in oligotrophic, cold extreme lake ecosystems is limited. These organisms are likely to suffer prolonged physiological stress, which may account for the highly variable growth rates seen within and between Antarctic lakes.
Graded paraconsistency
(2000)
Im Artikel wird an die Konzeptionen von Roman Jakobson und Jan Mukarovsky angeknüpft. Untersucht werden die Beziehungen zwischen Form (Signifiant), Inhalt (Signifié) und Denotat auf der semiotischen Ebene des Textes, wobei symbolische, ikonische und indexikalische Zeichenbeziehungen und Probleme der Translation erörtert werden. Der Beitrag richtet sich sowohl an Sprach-, Literatur- wie Übersetzungswissenschaftler.
The spectra of 18 WN stars in the Large Magellanic Cloud (LMC) are quantitatively analyzed by means of "standard" Wolf-Rayet model atmospheres, using the helium and nitrogen lines as well as the spectral energy distribution. The hydrogen abundance is also determined. Carbon is included for a subset of 4 stars. The studied sample covers all spectral subtypes (WN2 ... WN9) and also includes one WN/WC transition object. The luminosities of the program stars span a wide range ( L/Lsun = 5.0 ... 6.5). Due to the given LMC membership, these results are free from uncertainties inferred from the distance. 50 % of the studied stars (both, late and early WN subtypes) have rather low luminosity (L/Lsun < 5.5). This puts tough constraints on their evolutionary formation. If coming from single stars, it provides evidence for strong internal mixing processes. The empirical mass-loss rates are scaled down by a factor of about two due to the impact of clumping, compared to previous studies adopting homogeneous winds. There is no obvious strong correlation between the mass-loss rates and other parameters like luminosity, temperature and composition. The stellar parameters for the present LMC sample are not systematically different from those of the Galactic WN stars studied previously with the same techniques, in contrast to the expected metallicity effects.
Significant inferences
(2000)
Climatic changes are of major importance in landslide generation in the Argentine Andes. Increased humidity as a potential influential factor was inferred from the temporal clustering of landslide deposits during a period of significantly wetter climate, 30,000 years ago. A change in seasonality was tested by comparing past (inferred from annual-layered lake deposits, 30,000 years old) and modern (present-day observations) precipitation changes. Quantitative analysis of cross recurrence plots were developed to compare the influence of the El Nino/Southern Oscillation (ENSO) on present and past rainfall variations. This analysis has shown the stronger influence of NE trades in the location of landslide deposits in the intra-andean basin and valleys, what caused a higher contrast between summer and winter rainfall and an increasing of precipitation in La Nina years. This is believed to reduce thresholds for landslide generation in the arid to semiarid intra-andean basins and valleys.
Population biologists have long been interested in the oscillations in population size displayed by many organisms in the field and Laboratory. A wide range of deterministic mathematical models predict that these fluctuations can be generated internally by nonlinear interactions among species and, if correct, would provide important insights for understanding and predicting the dynamics of interacting populations. We studied the dynamical behavior of a two- species aquatic Laboratory community encompassing the interactions between a demographically structured herbivore population, a primary producer, and a mineral resource, yet still amenable to description and parameterization using a mathematical model. The qualitative dynamical behavior of our experimental system, that is, cycles, equilibria, and extinction, is highly predictable by a simple nonlinear model.
Die vierte Dimension
(2000)
Existence and semiclassical analysis of the total scattering cross-section for atom-ion collisaions
(2000)
In-plane strain and shape analysis of Si/SiGe nanostructures by grazing incidence diffraction
(2000)
The effect of additive noise on transitions in nonlinear systems far from equilibrium is studied. It is shown that additive noise in itself can induce a hidden phase transition, which is similar to the transition induced by multiplicative noise in a nonlinear oscillator [P. Landa and A. Zaikin, Phys. Rev. E 54, 3535 (1996)]. Investigation of different nonlinear models that demonstrate phase transitions induced by multiplicative noise shows that the influence of additive noise upon such phase transitions can be crucial: additive noise can either blur such a transition or stabilize noise-induced oscillations.
A dust cloud around Ganymede Maintained by hypervelocity impacts of interplanetary micrometeoroids
(2000)
Doubly stochastic resonance
(2000)
We report the effect of doubly stochastic resonance which appears in nonlinear extended systems if the influence of noise is twofold: A multiplicative noise induces bimodality of the mean field of the coupled network and an independent additive noise governs the dynamic behavior in response to small periodic driving. For optimally selected values of the additive noise intensity stochastic resonance is observed, which is manifested by a maximal coherence between the dynamics of the mean field and the periodic input. Numerical simulations of the signal-to-noise ratio and theoretical results from an effective two state model are in good quantitative agreement.
Standard time and frequency parameters of heart rate variability (HRV) describe only linear and periodic behaviour, whereas more complex relationships cannot be recognised. A method that may be capable of assessing more complex properties is the non-linear measure of 'renormalised entropy.' A new concept of the method, RE(AR), has been developed, based on a non-linear renormalisation of autoregressive spectral distributions. To test the hypothesis that renormalised entropy may improve the result of high-risk stratification after myocardial infarction, it is applied to a clinical pilot study (41 subjects) and to prospective data of the St George's Hospital post- infarction database (572 patients). The study shows that the new RE(AR) method is more reproducible and more stable in time than a previously introduced method (p<0.001). Moreover, the results of the study confirm the hypothesis that on average, the survivors have negative values of RE(AR) (-0.11+/-0.18), whereas the non-survivors have positive values (0.03+/-0.22, p<0.01). Further, the study shows that the combination of an HRV triangular index and RE(AR) leads to a better prediction of sudden arrhythmic death than standard measurements of HRV. In summary, the new RE(AR) method is an independent measure in HRV analysis that may be suitable for risk stratification in patients after myocardial infarction.
Quantum games
(2000)
In these lecture notes we investigate the implications of the identification of strategies with quantum operations in game theory beyond the results presented in [J. Eisert, M. Wilkens, and M. Lewenstein, Phys. Rev. Lett. 83, 3077 (1999)]. After introducing a general framework, we study quantum games with a classical analogue in order to flesh out the peculiarities of game theoretical settings in the quantum domain. Special emphasis is given to a detailed investigation of different sets of quantum strategies.
We analyze the variability in the x-ray lightcurves of the black hole candidate Cygnus X-1 by linear and nonlinear time series analysis methods. While a linear model describes the overall second order properties of the observed data well, surrogate data analysis reveals a significant deviation from linearity. We discuss the relation between shot noise models usually applied to analyze these data and linear stochastic autoregressive models. We debate statistical and interpretational issues of surrogate data testing for the present context. Finally, we suggest a combination of tools from linear and nonlinear time series analysis methods as a procedure to test the predictions of astrophysical models on observed data.
An unresolved discussion in contemporary ecology deals with the relative importance of competition along environmental gradients. In deserts, local-scale differences in environmental productivity may be caused by the presence of shrubs, which represent a favorable habitat for annual populations within a nutrient-poor matrix. In this study, we attempted to test the hypothesis that facilitation of desert annuals by shrubs increase the intensity of competition among the annual plants. Such negative indirect effects have so far been ignored in studies about plant-plant interactions. We tested our hypothesis by measuring seedling survival and fecundity of four abundant annual plant species with and without neighbors in open areas and under shrub canopies in a sandy desert area. Our findings did not indicate indirect negative effects of shrubs on their understory annuals. Sensitivity to the presence of neighbors varied between species and surprisingly, the species with the smallest seeds was the only one which was not negatively affected by the presence of neighbors. In contrast to our hypothesis, there was no difference between the habitat types shrubs and openings in absolute and relative competition intensity. Our overall results suggest that negative indirect effects of shrubs are unimportant in determining demographic response of understory annual plants.
Recently, numerous studies have pointed to the importance of positive interactions in natural communities. There is now a broad consensus that the balance between negative and positive interactions should shift along environmental gradients, with competition prevailing under environmentally benign conditions and positive interactions dominating under harsh conditions. A commonly cited example of the importance of facilitation in harsh environments is the preference of desert annual plants for the areas under the canopy of shrubs. The recognition of apparently positive effects of desert shrubs on annuals, however, has been mostly based on density measurements, while fitness parameters of the understory plants have been ignored. Also, the temporal consistency of such effects has not been previously tested. Based on conceptual ideas about the balance between interference and facilitation, we predicted that positive effects of the shrubs on the understory should dominate in dry years, while in favorable years, negative effects would be stronger. We tested our hypothesis by measuring the direction and magnitude of the shrub effect on demographic responses of four desert annual plant species during four consecutive seasons of differing rainfall. The results contradicted our initial hypothesis. Depending on the species, the effect of the shrubs shifted from either negative to neutral or from neutral to positive with increasing annual rainfall. However, this trend was stronger for the effect of shrubs on plant reproductive success than on their densities. Our data highlight the importance of measuring fitness parameters in studies of plant-plant interactions. We suggest that the negative effects of shrubs on plant fitness were due to rainfall interception, while positive effects were related to increased nutrient availability beneath shrubs. However, the mechanisms by which the shrubs and annuals interact can only be resolved using an experimental approach. Our results contradict previous hypotheses about the relative importance of positive and negative interactions along environmental gradients. A simple conceptual model summarizing the proposed role of rainfall in determining the direction of shrub effects on their understory annuals is presented.