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Question: Is there a relationship between size and death in the Iona-lived, deep-rooted tree, Acacia erioloba, in a semi-arid savanna? What is the size-class distribution of A. erioloba mortality? Does the mortality distribution differ from total tree size distribution? Does A. erioloba mortality distribution match the mortality distributions recorded thus far in other environments? Location: Dronfield Ranch, near Kimberley, Kalahari, South Africa. Methods: A combination of aerial photographs and a satellite image covering 61 year was used to provide long-term spatial data on mortality. We used aerial photographs of the study area from 1940, 1964, 1984, 1993 and a satellite image from 2001 to follow three plots covering 510 ha. We were able to identify and individually follow ca. 3000 individual trees from 1940 till 2001. Results: The total number of trees increased over time. No relationship between total number of trees and mean tree size was detected. There were no trends over time in total number of deaths per plot or in size distributions of dead trees. Kolmogorov-Smirnov tests showed no differences in size class distributions for living trees through time. The size distribution of dead trees was significantly different from the size distribution of all trees present on the plots. Overall, the number of dead trees was low in small size classes, reached a peak value when canopy area was 20 - 30 m(2), and declined in lamer size-classes. Mortality as a ratio of dead vs. total trees peaked at intermediate canopy sizes too. Conclusion: A. erioloba mortality was size-dependent, peaking at intermediate sizes. The mortality distribution differs from all other tree mortality distributions recorded thus far. We suggest that a possible mechanism for this unusual mortality distribution is intraspecific competition for water in this semi-arid environment.
Female extra-pair mating, fitness and genetic diversity: Expression in socially monogamous Coal Tits
(2006)
Hypersubstitutions are mappings which map operation symbols to terms. Terms can be visualized by trees. Hypersubstitutions can be extended to mappings defined on sets of trees. The nodes of the trees, describing terms, are labelled by operation symbols and by colors, i.e. certain positive integers. We are interested in mappings which map differently-colored operation symbols to different terms. In this paper we extend the theory of hypersubstitutions and solid varieties to multi-hypersubstitutions and colored solid varieties. We develop the interconnections between such colored terms and multihypersubstitutions and the equational theory of Universal Algebra. The collection of all varieties of a given type forms a complete lattice which is very complex and difficult to study; multi-hypersubstitutions and colored solid varieties offer a new method to study complete sublattices of this lattice.
In his short paper of 1886, the neogrammarian linguist Delbruck sketches his views on normal language processing and their relevance for the interpretation of some of the symptoms of progressive anomic aphasia. In particular, he discusses proper name impairments, verb and abstract noun superiority and the predominance of semantically related errors. Furthermore, he suggests that part of speech, morphology and word order may be preserved in this condition. This historical document has been lost in oblivion but the original ideas and their relevance for contemporary discussions merit a revival.
Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of poly(butyl acrylate) as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block poly(dimethylacrylamide), the strongly hydrophilic poly(acryloyloxyethyl methylsulfoxide), and the thermally sensitive poly(N-acryloylpyrrolidine). Aqueous micellar solutions of the block copolymers were prepared and characterized by static and dynamic light scattering analysis (DLS and SLS). No critical micelle concentration could be detected. The micellization was thermodynamically favored, although kinetically slow, exhibiting a marked dependence on the preparation conditions. The polymers formed micelles with a hydrodynamic diameter from 20 to 100 nm, which were stable upon dilution. The micellar size was correlated with the composition of the block copolymers and their overall molar mass. The micelles formed with the two most hydrophilic blocks were particularly stable upon temperature cycles, whereas the thermally sensitive poly(N-acryloylpyrrolidine) block showed a temperature-induced precipitation. According to combined SLS and DLS analysis, the micelles exhibited an elongated shape such as rods or worms. It should be noted that the block copolymers with the most hydrophilic poly(sulfoxide) block formed inverse micelles in certain organic solvents.
Recurrence plot analyses suggest a novel reference system involved in newborn spontaneous movements
(2006)
The movements of newborns have been thoroughly studied in terms of reflexes, muscle synergies, leg coordination, and target-directed arm/hand movements. Since these approaches have concentrated mainly on separate accomplishments, there has remained a clear need for more integrated investigations. Here, we report an inquiry in which we explicitly concentrated on taking such a perspective and, additionally, were guided by the methodological concept of home base behavior, which Ilan Golard developed for studies of exploratory behavior in animals. Methods from nonlinear dynamics, such as symbolic dynamics and recurrence plot analyses of kinematic data received from audiovisual newborn recordings, yielded new insights into the spatial and temporal organization of limb movements. In the framework of home base behavior, our approach uncovered a novel reference system of spontaneous newborn movements.
Background: The biological interpretation of large-scale gene expression data is one of the paramount challenges in current bioinformatics. In particular, placing the results in the context of other available functional genomics data, such as existing bio-ontologies, has already provided substantial improvement for detecting and categorizing genes of interest. One common approach is to look for functional annotations that are significantly enriched within a group or cluster of genes, as compared to a reference group. Results: In this work, we suggest the information-theoretic concept of mutual information to investigate the relationship between groups of genes, as given by data-driven clustering, and their respective functional categories. Drawing upon related approaches (Gibbons and Roth, Genome Research 12: 1574-1581, 2002), we seek to quantify to what extent individual attributes are sufficient to characterize a given group or cluster of genes. Conclusion: We show that the mutual information provides a systematic framework to assess the relationship between groups or clusters of genes and their functional annotations in a quantitative way. Within this framework, the mutual information allows us to address and incorporate several important issues, such as the interdependence of functional annotations and combinatorial combinations of attributes. It thus supplements and extends the conventional search for overrepresented attributes within a group or cluster of genes. In particular taking combinations of attributes into account, the mutual information opens the way to uncover specific functional descriptions of a group of genes or clustering result. All datasets and functional annotations used in this study are publicly available. All scripts used in the analysis are provided as additional files.
We report quantum chemical calculations, mostly based on density functional theory, on azobenzene and substituted azobenzenes as neutral molecules or ions, in ground and excited states. Both the cis and trans configurations are computed as well as the activation energies to transform one isomer into the other and the possible reaction paths and reaction surfaces along the torsion and inversion modes. All calculations are done for the isolated species, but results are discussed in light of recent experiments aiming at the switching of surface mounted azobenzenes by scanning tunneling microscopes.
Dynamic service adaptation
(2006)
Change can be observed in our environment and in the technology we build. While changes in the environment happen continuously and implicitly, our technology has to be kept in sync with the changing world around it. Although we can prepare for some of the changes for most of them we cannot. This is especially true for next-generation mobile communication systems that are expected to support the creation of a ubiquitous society where virtually everything is connected and made available within an organic information network. Resources will frequently join or leave the network, new types of media or new combinations of existing types will be used to interact and cooperate, and services will be tailored to preferences and needs of individual customers to better meet their needs. This paper outlines our research in the area of dynamic service adaptation to provide concepts and technologies allowing for such environments. Copyright (C) 2006 John Wiley & Sons, Ltd.
We introduce a method for computing instantaneous-polarization attributes from multicomponent signals. This is an improvement on the standard covariance method (SCM) because it does not depend on the window size used to compute the standard covariance matrix. We overcome the window-size problem by deriving an approximate analytical formula for the cross-energy matrix in which we automatically and adaptively determine the time window. The proposed method uses polarization analysis as applied to multicomponent seismic by waveform separation and filtering.
Seasonal, host sex and age-related variations in helminth egg and coccidian oocyst counts were investigated in a naturally infected wild bushbuck (Tragelaphus scriptus) population in Queen Elizabeth National Park, western Uganda from April 2000 to February 2002. The prevalence and mean intensity quantified as the number of eggs and oocysts per gram of faeces were taken as a measure of parasite burdens. Host sex and age-related differences in prevalence values were not found but the overall prevalence of Eimeria sp. was significantly higher during the rainy season, and peak counts were recorded either during or soon after a peak rainfall. A similar trend was observed for Moniezia spp., although the results were marginally not significant. There were also no significant differences in mean intensity values, relative to host sex, age or season.
[ 1] In this paper, we discuss the origin of superswell volcanism on the basis of representation and analysis of recent gravity and magnetic satellite data with wavelets in spherical geometry. We computed a refined gravity field in the south central Pacific based on the GRACE satellite GGM02S global gravity field and the KMS02 altimetric grid, and a magnetic anomaly field based on CHAMP data. The magnetic anomalies are marked by the magnetic lineation of the seafloor spreading and by a strong anomaly in the Tuamotu region, which we interpret as evidence for crustal thickening. We interpret our gravity field through a continuous wavelet analysis that allows to get a first idea of the internal density distribution. We also compute the continuous wavelet analysis of the bathymetric contribution to discriminate between deep and superficial sources. According to the gravity signature of the different chains as revealed by our analysis, various processes are at the origin of the volcanism in French Polynesia. As evidence, we show a large-scale anomaly over the Society Islands that we interpret as the gravity signature of a deeply anchored mantle plume. The gravity signature of the Cook-Austral chain indicates a complex origin which may involve deep processes. Finally, we discuss the particular location of the Marquesas chain as suggesting that the origin of the volcanism may interfere with secondary convection rolls or may be controlled by lithospheric weakness due to the regional stress field, or else related to the presence of the nearby Tuamotu plateau.
Reliable information on small- and medium-sized enterprises (SMEs) is rare and costly for financial intermediaries. Therefore relationship banking is often considered as the appropriate lending technique. In this paper we offer a theoretical model to analyze relationship banking and the pricing behavior of banks in a Bertrand competition framework with monitoring costs. We show that the lack of reliable information leads to comparable high interest rates even if a long-term relationship between borrower and bank exists. The paper offers a theoretical explanation why SMEs often are faced with borrowing constraints.
Quantification of discrete pressure-temperature domains in deformed chlorite + white mica-bearing metapelites was undertaken on mineral compositions derived by two-dimensional microprobe compositional mapping of selected areas of rock thin sections. In order to achieve compositional information at sufficient analytical precision, spatial resolution and sample coverage within a typical analysis time of 1 day, an optimization of measurement methods was necessary. The method presented here allows collection of raw counts for eight different element concentrations at an analytical precision of similar to 1-2 wt%. X-ray intensity multiplane maps (one map per measured chemical element) are translated into concentration multiplane maps, utilizing selected conventionally measured spot analyses combined with the Castaing approximation for each mineral. As this step requires identification of the different minerals present in the mapped area, a statistical clustering technique to identify different groups of composition was developed, guided by simple petrographic inspection of the thin section, to delineate the important minerals in the mapped area. Finally, the compositions of each pixel are translated into a mineral structural formula thus yielding a new kind of image with a high content of petrological information. The reliability of the mineral composition images was emphasized by carrying out precision tests on the analytical data. The possible use of chemical maps to infer the P-T-deformation history of metamorphic rocks is illustrated with two samples from the Spitzbergen and the Sambagawa blueschist facies belts. In both samples, a strong correlation between structures and chemistry is observed. Qualitative estimates of P-T conditions from the Si-content of mica and chlorite are in good agreement with their location in microstructures that formed at different times. Therefore, the combination of chemical maps with microstructural observations is a very powerful approach to understand both the evolution of complex metamorphic rocks and the control by deformation of mineral reactivity.
Incremental Support Vector Machines (SVM) are instrumental in practical applications of online learning. This work focuses on the design and analysis of efficient incremental SVM learning, with the aim of providing a fast, numerically stable and robust implementation. A detailed analysis of convergence and of algorithmic complexity of incremental SVM learning is carried out. Based on this analysis, a new design of storage and numerical operations is proposed, which speeds up the training of an incremental SVM by a factor of 5 to 20. The performance of the new algorithm is demonstrated in two scenarios: learning with limited resources and active learning. Various applications of the algorithm, such as in drug discovery, online monitoring of industrial devices and and surveillance of network traffic, can be foreseen.
Successful pain treatment in arthropathic lower extremities by acupuncture in haemophilia patients
(2006)
Acupuncture is successfully used in the treatment of degenerative osteoarthritis. The treatment of haemophilic arthropathies can require strong painkillers with severe side-effects. Therefore, a special yet simple acupuncture technique was evaluated in the treatment of these joint problems. Twelve patients with a factor VIII activity < 1% and at least one painful arthropathy in both lower extremities were included in this single-blinded study. The non-treated side served as a control. Treatment was assessed by a visual analogue scale (VAS) and an orthopaedic clinical examination. Only one needle was inserted at the rear fontanelle once per week and in 15 cycles. Ten of 12 patients showed an improvement of their pain perception. The average VAS could be reduced from 6.8 to 5.0. The side not receiving treatment showed a reduction from 4.1 to 4.0. No side-effects were observed. Even though interpretation of our data are limited due to the small patient numbers, significant improvement of the VAS after treatment suggests that acupuncture has a measurable positive effect in pain management for haemophilic arthropathy of the lower extremities.
Plastidial phosphorylase is required for normal starch synthesis in Chlamydomonas reinhardtii
(2006)
Among the three distinct starch phosphorylase activities detected in Chlamydomonas reinhardtii, two distinct plastidial enzymes (PhoA and PhoB) are documented while a single extraplastidial form (PhoC) displays a higher affinity for glycogen as in vascular plants. The two plastidial phosphorylases are shown to function as homodimers containing two 91-kDa (PhoA) subunits and two 110-kDa (PhoB) subunits. Both lack the typical 80-amino-acid insertion found in the higher plant plastidial forms. PhoB is exquisitely sensitive to inhibition by ADP-glucose and has a low affinity for malto-oligosaccharides. PhoA is more similar to the higher plant plastidial phosphorylases: it is moderately sensitive to ADP-glucose inhibition and has a high affinity for unbranched malto-oligosaccharides. Molecular analysis establishes that STA4 encodes PhoB. Chlamydomonas reinhardtii strains carrying mutations at the STA4 locus display a significant decrease in amounts of starch during storage that correlates with the accumulation of abnormally shaped granules containing a modified amylopectin structure and a high amylose content. The wild-type phenotype could be rescued by reintroduction of the cloned wild-type genomic DNA, thereby demonstrating the involvement of phosphorylase in storage starch synthesis.
Experimental results show that the polymerization of pyrrole in the presence of beta-naphthalenesulfonic acid and different fluorosurfactants like perfluorooctanesulfonic acid, perfluorooctyldiethanolamide, and ammonium perfluorooctanoate leads to polypyrrole with special morphologies, such as rings or disks and rectangular frames or plates. The formation of these unusually shaped particles of polymer dispersions is explained by the chemical and colloidal peculiarities of the oxidative pyrrole polymerization with ammonium peroxodisulfate in aqueous medium.
Sexual dimorphism is expressed as median of the female values in percent of the median of the male values, of 4 length measurements, 3 circumferences, and 5 measurements of corpulence respectively fat. Data were obtained from a cross-sectional sample of more than 41.000 German subjects, aged from birth to age 62. The pattern of sexual dimorphism is similar in the length measurements. Girls are shorter at birth, but they increase in length at higher rates than boys and even temporarily overgrow the boys up to age 12. Thereafter, males show an obvious growth advantage leading to some 6 to 9% more length in adult males. In contrast, female circumferences are always smaller, from birth to senescence. Though, the differences between the sexes are low in circumferences, up to age 13, sexual dimorphism increases to 17% in the thoracic circumference at adulthood. Sexual dimorphism in weight and BMI is comparably with that in length measurements while subcutaneous fat and total body fat content are always higher in females. The results highlight that sexual dimorphism develops at different pace in the various components of the body and that it associates with a sex specific growth tempo.
The efficient time integration of the dynamic core equations for numerical weather prediction (NWP) remains a key challenge. One of the most popular methods is currently provided by implementations of the semi-implicit semi-Lagrangian (SISL) method, originally proposed by Robert (J. Meteorol. Soc. Jpn., 1982). Practical implementations of the SISL method are, however, not without certain shortcomings with regard to accuracy, conservation properties and stability. Based on recent work by Gottwald, Frank and Reich (LNCSE, Springer, 2002), Frank, Reich, Staniforth, White and Wood (Atm. Sci. Lett., 2005) and Wood, Staniforth and Reich (Atm. Sci. Lett., 2006) we propose an alternative semi-Lagrangian implementation based on a set of regularized equations and the popular Stormer-Verlet time stepping method in the context of the shallow-water equations (SWEs). Ultimately, the goal is to develop practical implementations for the 3D Euler equations that overcome some or all shortcomings of current SISL implementations.
Glucan, water dikinase (GWD) and phosphoglucan, water dikinase (PWD) are required for normal starch metabolism. We analysed starch phosphorylation in Arabidopsis wildtype plants and mutants lacking either GWD or PWD using P-31 NMR. Phosphorylation at both C6- and C3-positions of glucose moieties in starch was drastically decreased in GWD-deficient mutants. In starch from PWD-deficient plants C3-bound phosphate was reduced to levels close to the detection limit. The latter result contrasts with previous reports according to which GWD phosphorylates both C6- and C3-positions. In these studies, phosphorylation had been analysed by HPLC of acid-hydrolysed glucans. We now show that maltose-6-phosphate, a product of incomplete starch hydrolysis, co-eluted with glucose-3-phosphate under the chromatographic conditions applied. Re-examination of the specificity of the dikinases using an improved method demonstrates that C6- and C3-phosphorylation is selectively catalysed by GWD and PWD, respectively.
The AtNFXL1 gene encodes a NF-X1 type zinc finger protein required for growth under salt stress
(2006)
The human NF-X1 protein and homologous proteins in eukaryotes represent a class of transcription factors which are characterised. by NF-X1 type zinc finger motifs. The Arabidopsis genome encodes two NF-X1 homologs, which we termed AtNFXL1 and AtNFXL2. Growth and survival was impaired in atnfxl1 knock-out mutants and AtNFXL1-antisense plants under salt stress in comparison to wild-type plants. In contrast, 35S: :AtNFXL1 plants showed higher survival rates. The AtNFXL2 protein potentially plays an antagonistic role. The Arabidopsis NF-X1 type zinc finger proteins likely are part of regulatory mechanisms, which protect major processes such as photosynthesis.
The fabrication of compartmented micellar systems is an exciting new area of research in the field of polymer self-assembly. Multicompartment micelles composed of a water-soluble shell and a segregated hydrophobic core can be obtained via direct aqueous self-assembly of preformed polymeric amphiphiles possessing one hydrophilic segment and two incompatible hydrophobic segments (e.g. hydrocarbon and fluorocarbon blocks). Such macromolecular building-blocks were prepared in the present work principally via reversible addition-fragmentation transfer polymerization (RAFT). Polysoaps or triblock macrosurfactants can be synthesized in high yields by RAFT under relatively straightforward experimental conditions.
[1] We document late Pleistocene - Holocene aggradation and incision processes at the mountain front of the Qilian Shan, an active intracontinental fold-and-thrust belt accommodating a significant portion of the India-Asia convergence. The Shiyou River cuts through a NNE vergent fault propagation fold with Miocene red beds in the core and Pliocene - Quaternary growth strata on the northern forelimb. South of the anticline, Miocene strata dip 20 degrees SSW, suggesting a similar orientation for the basal decollement. After aggradation of an similar to 150-m-thick, late Pleistocene valley fill, the Shiyou River formed three terraces. The highest terrace, located 170 m above the river, constitutes the top of the fill. The other terraces are fill cut terraces: their treads are located 130 - 105 m and 37 m above the river, respectively. The 10 Be exposure dating of the terraces suggests that river incision accelerated from 0.8 +/- 0.2 mm yr(-1) to similar to 10 mm yr(-1) at 10 - 15 kyr. We interpret fast Holocene river incision as largely unrelated to tectonic forcing. The late Pleistocene incision rate of 0.8 +/- 0.2 mm yr(-1) places an upper limit of 2.2 +/- 0.5 mm yr(-1) on the horizontal shortening rate, assuming that incision is solely caused by rock uplift above a decollement dipping 20 degrees. However, the actual shortening rate may lie between similar to 2.2 mm yr(-1) and zero because deformation of the terraces and the valley fill cannot be unequivocally demonstrated. Our estimate is consistent with the bulk shortening rate of similar to 5 - 10 mm yr(-1) across several faults in NE Tibet derived from neotectonic and GPS data, although in case of the Shiyou River, Holocene deformation is barely discernible owing to intense climate-induced river incision.
Many semi-arid regions are characterised by water scarcity and vulnerability of natural resources, pronounced climatic variability and social stress. Integrated studies including climatotogy, hydrology, and socio-econornic studies are required both for analysing the dynamic natural conditions and to assess possible strategies to make semi-arid regions Less vulnerable to the present and changing climate. The model introduced here dynamically describes the retationships between climate forcing, water availability, agriculture and selected societal processes. The model has been tailored to simulate the rather complex situation in the semi-and north-eastern Brazil in a quantitative manner including the sensitivity to external forcing, such as climate change. The selected results presented show the general functioning of the integrated model, with a primary focus on climate change impacts. It becomes evident that due to Large differences in regional climate scenarios, it is still impossible to give quantitative values for the most probable development, e.g., to assign probabilities to the simulated results. However, it becomes clear that water is a very crucial factor, and that an efficient and ecologically sound water management is a key question for the further development of that semi-arid region. The simulation results show that, independent of the differences in climate change scenarios, rain-fed farming is more vulnerable to drought impacts compared to irrigated farming. However, the capacity of irrigation and other water infrastructure systems to enhance resilience in respect to climatic fluctuations is significantly constrained given a significant negative precipitation trend. (c) 2005 Elsevier B.V. All rights reserved.
Simulation models that describe autonomous individual organisms (individual based models, IBM) or agents (agent-based models, ABM) have become a widely used tool, not only in ecology, but also in many other disciplines dealing with complex systems made up of autonomous entities. However, there is no standard protocol for describing such simulation models, which can make them difficult to understand and to duplicate. This paper presents a proposed standard protocol, ODD, for describing IBMs and ABMs, developed and tested by 28 modellers who cover a wide range of fields within ecology. This protocol consists of three blocks (Overview, Design concepts, and Details), which are subdivided into seven elements: Purpose, State variables and scales, Process overview and scheduling, Design concepts, Initialization, Input, and Submodels. We explain which aspects of a model should be described in each element, and we present an example to illustrate the protocol in use. In addition, 19 examples are available in an Online Appendix. We consider ODD as a first step for establishing a more detailed common format of the description of IBMs and ABMs. Once initiated, the protocol will hopefully evolve as it becomes used by a sufficiently large proportion of modellers. (c) 2006 Elsevier B.V. All rights reserved.
In this study we present iterative regularization methods using rational approximations, in particular, Pade approximants, which work well for ill-posed problems. We prove that the (k,j)-Pade method is a convergent and order optimal iterative regularization method in using the discrepancy principle of Morozov. Furthermore, we present a hybrid Pade method, compare it with other well-known methods and found that it is faster than the Landweber method. It is worth mentioning that this study is a completion of the paper [A. Kirsche, C. Bockmann, Rational approximations for ill-conditioned equation systems, Appl. Math. Comput. 171 (2005) 385-397] where this method was treated to solve ill-conditioned equation systems. (c) 2006 Elsevier Inc. All rights reserved.
Three methods for the determination of the surface tension of liquids based on force measurements namely, the vertical plate method of Wilhelmy, the frame method of Lenard and the ring method of du Nouy are compared and studied in respect of a common principle of correction. It is shown that these three most important force-based methods allow the determination of the surface tension under static conditions. The force components of the corresponding liquid column below the measuring wire obtained for the straight part of the withdrawal curve up to the transition in its curved part provides exact surface tension values. The experimentally accessible value of the force component describes the physical background of the measured value correction contrary to the approximate equations obtained by mathematical way. Usually the determination of surface tension of liquids is based merely at the vertical plate method on exact equations thermodynamically derived whereas in the case of the frame and ring methods correction factors in approximate equations are used. At usual application of the force-based methods under the non-static condition of the withdrawal of a liquid column, the force maximum measured at withdrawal of the measuring object (plate, frame, or ring) is the basis for the determination of surface tension. In these cases, the measured surface tension values are compensated by correction equations for the frame and ring methods which are based on an correction factor and correction tables empirically obtained. The surface tension values obtained in this usual way agree with those obtained by using the force component of the corresponding liquid column below the measuring wire for the straight part of the withdrawal curve up to the transition in its curved part. Problems arising at the force measurements with increasing thickness of the measuring wires inside and outside the rings are discussed.
A 741-cm-long laminated sediment core, covering the last 10,800 years was collected from Lake Zigetang, central Tibetan Plateau (90.9 degrees E, 32.0 degrees N, 4560m a.s.l.), and analysed palynologically at 69 horizons. Biome reconstruction suggests a dominance of temperate steppe vegetation (mainly Artemisia and Poaceae) on the central Tibetan Plateau during the first half of the Holocene (10.8-4.4 cal. ka BP), while alpine steppes with desert elements (mainly Cyperaceae, Poaceae, Chenopodiaceae, and characteristic high-alpine herb families) tend to dominate the second half (4.4-0 cal. ka BP). The Artemisia/Cyperaceae ratio-a semi-quantitative measure for summer temperature-indicates a general cooling trend throughout the Holocene. Dense temperate steppe vegetation and maximum desert plant withdrawal, however, indicate that a suitable balance of wet and warm conditions for optimum vegetation growth likely occurred during the middle Holocene (7.3-4.4 cal. ka BP). Severe Early Holocene cold events have been reconstructed for 8.7-8.3 and similar to 7.4 cal. ka BP. (c) 2006 Elsevier Ltd and INQUA. All rights reserved.
A time-staggered semi-Lagrangian discretization of the rotating shallow-water equations is proposed and analysed. Application of regularization to the geopotential field used in the momentum equations leads to an unconditionally stable scheme. The analysis, together with a fully nonlinear example application, suggests that this approach is a promising, efficient, and accurate alternative to traditional schemes.
Between reasoning
(2006)
In two experiments we investigated three-term reasoning with spatial relational assertions using the preposition between as compared to projective prepositions (such as to the left of). For each kind of assertion we distinguish the referent expression (i.e., the grammatical subject) from the relatum expression (i.e., the internal argument of the preposition; e.g., [The hedgehog](referent)_(expression) is to the left of [the frog](relatum)_(expression); [the snake](referent)_(expression) is between [the donkey and the deer](relatum)_(expression)). Previous research has shown that integrating premises with projective prepositions is easier (a) when the relatum expression of the second premise denotes an element already given by the first premise (relatum = given), and (b) when the term denoting a given element precedes the term denoting a new element (given - new). Experiment 1 extended this finding to second premises with the preposition between. In Experiment 2, between figured in the first premise. In this case, participants built an initial preferred model already from the first premise, although such a premise is indeterminate with respect to the array that it describes. Since there is no need left for integrating the second premise, this premise is instead used to verify the initial model and to modify it when necessary. A further investigation of conclusion evaluation times showed that conclusions were evaluated faster when they first mentioned the element that was included most recently into the mental model of the premises. The use of premises with between permitted the separation of recency of model inclusion from recency of appearance of an element in a premise.
Introduction to special issue: Dynamics of seismicity patterns and earthquake triggering - Preface
(2006)
The velocity distribution function of granular gases in the homogeneous cooling state as well as some heated granular gases decays for large velocities as f proportional to exp(-const x nu). That is, its high-energy tail is overpopulated as compared with the Maxwell distribution. At the present time, there is no theory to describe the influence of the tail on the kinetic characteristics of granular gases. We develop an approach to quantify the overpopulated tail and analyze its impact on granular gas properties, in particular on the cooling coefficient. We observe and explain anomalously slow relaxation of the velocity distribution function to its steady state.
Fractional crystallization of peraluminous F- and H(2)O-rich granite magmas progressively enriches the remaining melt with volatiles. We show that, at saturation, the melt may separate into two immiscible conjugate melt fractions, one of the fractions shows increasing peraluminosity and the other increasing peralkalinity. These melt fractions also fractionate the incompatible elements to significantly different degrees. Coexisting melt fractions have differing chemical and physical properties and, due to their high density and viscosity contrasts, they will tend to separate readily from each other. Once separated, each melt fraction evolves independently in response to changing T/P/X conditions and further immiscibility events may occur, each generating its own conjugate pair of melt fractions. The strongly peralkaline melt fractions in particular are very reactive and commonly react until equilibrium is attained. Consequently, the peralkaline melt fraction is commonly preserved only in the isolated melt and mineral inclusions. We demonstrate that the differences between melt fractions that can be seen most clearly in differing melt inclusion compositions are also visible in the composition of the resulting ore-forming and accessory minerals, and are visible on scales from a few micrometers to hundreds of meters.
Questions of identity and provenance of minerals that are parts of masterpieces in museums have become increasingly important in mineralogical and historical studies. Detailed investigations of valuable and unique objects require on-site, nondestructive and noninvasive methods because touching or removing them may cause irreparable damage. A mobile Raman-microprobe has been used to meet these demands for truly in situ mineralogical studies of the large collection of minerals and rocks of the Prussian kings in the Grotto Hall (Grottensaal) of the New Palace (Neues Palais), Park Sanssouci in Potsdam. Minerals on the walls of the Grotto Hall were analyzed to identify them and thereby to complete the data bank of the collection. Fluid and solid inclusions in the interior of a large quartz crystal have been studied to provide evidence of the provenance of the crystal. The fluid inclusions contain aqueous saline solutions, whereas the solid inclusions are needles of anhydrite with a length of about 1.5 mm. The quartz probably originated from an area in the eastern Alps, from the surroundings of Bad Gastein, Austria. This is the first on-site and in situ study of inclusions below the surface of a mineral with a mobile Raman-microprobe outside a laboratory.
This paper discusses translocation features of the 20S proteasome in order to explain typical proteasome length distributions. We assume that the protein transport depends significantly on the fragment length with some optimal length which is transported most efficiently. By means of a simple one-channel model, we show that this hypothesis can explain both the one- and the three-peak length distributions found in experiments. A possible mechanism of such translocation is provided by so-called fluctuation-driven transport.
A cysteine mutant of a monomeric human Cu, Zn-SOD (Glycine 61, Serine 142) has been immobilized directly on gold electrodes using the thiol groups introduced. The electrochemical behavior of the surface confined protein was studied in mixtures of aqueous buffer and DMSO up to an organic solvent content of 60%. The formal potential was found to be rather independent of the DMSO content. However, half peak width increased and the redoxactive amount clearly decreased with raising DMSO content. In addition, the kinetics of the heterogeneous electron transfer became slower; but still a quasireversible electrochemical conversion of the mutant SOD was feasible. Thus, the electrodes were applied for sensorial superoxide detection. At a potential of +220 mV vs. Ag/AgCl advantage was taken of the partial oxidation reaction of the enzyme. A defined superoxide signal was obtained in solutions up to 40% DMSO. The sensitivity of the mutant electrodes decreased linearly with the organic solvent content in solution but was still higher compared to conventional cyt.c based sensors. At DMSO concentrations higher than 40% no sensor response was detected.
Archival X-ray spectra of the four prominent single, non-magnetic O stars zeta Pup, zeta Ori, xi Per and zeta Oph, obtained in high resolution with Chandra HETGS/MEG have been studied. The resolved X-ray emission line profiles provide information about the shocked, hot gas which emits the X-radiation, and about the bulk of comparably cool stellar wind material which partly absorbs this radiation. In this paper, we synthesize X-ray line profiles with a model of a clumpy stellar wind. We find that the geometrical shape of the wind inhomogeneities is important: better agreement with the observations can be achieved with radially compressed clumps than with spherical clumps. The parameters of the model, i.e. chemical abundances, stellar radius, mass-loss rate and terminal wind velocity, are taken from existing analyses of UV and optical spectra of the programme stars. On this basis, we also calculate the continuum-absorption coefficient of the cool-wind material, using the Potsdam Wolf-Rayet (POWR) model atmosphere code. The radial location of X-ray emitting gas is restricted from analysing the FIR line ratios of helium-like ions. The only remaining free parameter of our model is the typical distance between the clumps; here, we assume that at any point in the wind there is one clump passing by per one dynamical time-scale of the wind. The total emission in a model line is scaled to the observation. There is a good agreement between synthetic and observed line profiles. We conclude that the X-ray emission line profiles in O stars can be explained by hot plasma embedded in a cool wind which is highly clumped in the form of radially compressed shell fragments.
Cave animals are widely recognised as model organisms to study regressive evolutionary processes like the reduction of eyes. In this paper, we report on the regressive evolution of species discrimination in the cave molly, Poecilia mexicana, which, unlike other cave fishes, still has functional eyes. This allowed us to examine the response to both visual and non-visual cues involved in species discrimination. When surface-dwelling females were given a chance to associate with either a conspecific or a swordtail (Xiphophorus hellerii) female, they strongly preferred the conspecific female both when multiple cues and when solely visual cues were available to the female. No association preference was observed when only non-visual cues were provided. In contrast, cave-dwelling females showed no preference under all testing conditions, suggesting that species recognition mechanisms have been reduced. We discuss the role of species discrimination in relation to habitat differences.
Context. Very massive stars pass through the Wolf-Rayet (WR) stage before they finally explode. Details of their evolution have not yet been safely established, and their physics are not well understood. Their spectral analysis requires adequate model atmospheres, which have been developed step by step during the past decades and account in their recent version for line blanketing by the millions of lines from iron and iron-group elements. However, only very few WN stars have been re-analyzed by means of line-blanketed models yet. Aims. The quantitative spectral analysis of a large sample of Galactic WN stars with the most advanced generation of model atmospheres should provide an empirical basis for various studies about the origin, evolution, and physics of the Wolf-Rayet stars and their powerful winds. Methods. We analyze a large sample of Galactic WN stars by means of the Potsdam Wolf-Rayet (PoWR) model atmospheres, which account for iron line blanketing and clumping. The results are compared with a synthetic population, generated from the Geneva tracks for massive star evolution. Results. We obtain a homogeneous set of stellar and atmospheric parameters for the GalacticWN stars, partly revising earlier results. Conclusions. Comparing the results of our spectral analyses of the Galactic WN stars with the predictions of the Geneva evolutionary calculations, we conclude that there is rough qualitative agreement. However, the quantitative discrepancies are still severe, and there is no preference for the tracks that account for the effects of rotation. It seems that the evolution of massive stars is still not satisfactorily understood.
Great apes are the closest living relatives of humans. Physiological similarities between great apes and humans provide clues to identify which biological features in humans are primitive or derived from great apes. Vitamin A (VA) and carotenoid metabolism have been only partially studied in great apes, and comparisons between great apes and humans are not available. We aimed to investigate VA and carotenoid intake and plasma concentrations in great apes living in captivity, and to compare them to healthy humans. Dietary intakes of humans (n = 20) and, among the great apes, chimpanzees (n = 15) and orangutans (n = 5) were calculated. Plasma retinol (ROH), retinol-binding protein (RBP), retinyl esters, and major carotenoids were analyzed. The great ape diet was higher in VA than in humans, due to high intake of provitamin A carotenoids. Plasma ROH concentrations in great apes were similar to those in humans, but retinyl esters were higher in great apes than in humans. Differences in plasma carotenoid concentrations were observed between great apes and humans. Lutein was the main carotenoid in great apes, while P-carotene was the main carotenoid for humans. RBP concentrations did not differ between great apes and humans. The molar ratio of ROH to RBP was close to 1.0 in both great apes and humans. In conclusion, great apes show homeostatic ROH regulation, with high but physiological retinyl esters circulating in plasma. Furthermore, great apes show great selectivity in their plasmatic carotenoid concentration, which is not explained by dietary intake.
Lago Laja is a late Quaternary volcanic‐dammed lake located near the drainage divide of the south central Andes. Field observations, lake reflection seismic profiles, bathymetry, and remote sensing data reveal an active fault system that runs parallel to the volcanic arc along the axis of the Main Cordillera, the Lago Laja fault system (LLFS). Normal faults of this extensional system cut late Pleistocene volcanics, <7.1 ka still water lacustrine sediments, 6.3 ka pyroclastic deposits, and Holocene alluvial fans. We divide the LLFS in three segments on the basis of fault geometry, width, and slip magnitude. The underwater faults of the central segment in the lake's deepest part have the maximum Holocene vertical slip rate of >2.7 mm/yr. Since 7.1 ka, the LLFS accounts for ∼0.7% of arc‐normal extension at an average minimum rate of 1.2 mm/yr and strain rate of ∼10−14 s−1. Seismites and surface ruptures evidence M>6 paleoearthquakes. The Main Cordillera at ∼37°S is a large‐scale pop‐up structure uplifted by thrusting along its foothills. In this light, we interpret extension in the axial and highest part of the Andes as incipient synorogenic gravitational collapse in response to uplift and crustal thickening. Thermal weakening due to elevated heat flow and postglacial lithospheric rebound and unbending have probably contributed to the arc‐limited collapse and Holocene acceleration of deformation rates. The lack of significant strike‐slip offsets along the LLFS as well as along both foothills‐thrust systems at 37°S contrasts with the intra‐arc dextral fault zone south of 38°S. Regional structural data indicates that north of 38°S, diffusely distributed strain reflects low partitioning of oblique subduction, while to the south deformation is localized in a discrete strike‐slip fault zone along the volcanic arc, reflecting a higher degree of partitioning. We relate this strain partitioning gradient to favorable fault orientations in the fore arc north of the Arauco Peninsula, a major seismotectonic boundary.
The influence of branched poly(ethyleneimine) on the phase behavior of the system sodium dodecylsulfate/toluene-pentanol (1:1)/water has been studied. The isotropic microemulsions still exist when water is replaced with aqueous solutions of PEI (up to 30% in weight), but their stability is significantly influenced. From a polymer concentration of 20 wt%, the polymer enhances the solubilization of water in oil, changes the sign of the spontaneous curvature of the surfactant film, and induces an inversion of the microemulsion type from water-in-oil (L-2) to oil-in-water (L-1), by the formation of a bicontinuous channel. Further investigations show that the addition of polymer in the L-2 phase changes the droplet-droplet interactions as the conductivity drops and the percolation disappears. In the bicontinuous channel, higher viscosities can be detected, as well as a weak percolation followed by a steep increase of the conductivity, which can be related to evident structural changes in the system. DSC measurements allow then to follow the changes of the water properties in the system, from interfacial-water in the L-2 phase to free-water in the sponge-like phase. Finally, all the measurements performed permit to characterize the structural transitions in the system and to understand the role of the added polymer.