TY - JOUR A1 - Wessig, Pablo A1 - Matthes, Annika A1 - Pick, Charlotte T1 - The photo-dehydro-Diels-Alder (PDDA) reaction JF - Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry N2 - The photo-dehydro-Diels-Alder (PDDA) reaction is a valuable extension of the classical Diels-Alder (DA) reaction. The PDDA reaction differs from the DA reaction by the replacement of one of the C-C-double bonds of the diene moiety by a C-C triple bond and by the photochemical triggering of the reaction. This entails that, in contrast to the DA reaction, the PDDA reaction proceeds according to a multistage mechanism with biradicals and cycloallenes as intermediates. The PDDA reaction provides access to a considerable variety of compound classes. For example, 1-phenylnaphthlenes, 1,1'-binaphthyls, N-heterocyclic biaryls, and naphthalenophanes could be obtained by this reaction. Y1 - 2011 U6 - https://doi.org/10.1039/c1ob06066j SN - 1477-0520 VL - 9 IS - 22 SP - 7599 EP - 7605 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hölter, Frank T1 - Suzuki-Miyaura cross coupling reactions with Phenoldiazonium salts JF - Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry N2 - The Suzuki-Miyaura coupling of phenol diazonium salts and aryl trifluoroborates yields 4-hydroxybiaryls in a protecting group-free synthesis. Y1 - 2011 U6 - https://doi.org/10.1039/c1ob05256j SN - 1477-0520 VL - 9 IS - 13 SP - 4914 EP - 4920 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Laemmermann, Anica A1 - Kühn, Heiner T1 - The anisotropic effect of functional groups in H-1 NMR spectra is the molecular response property of spatial nucleus independent chemical shifts (NICS)-Conformational equilibria of exo/endo tetrahydrodicyclopentadiene derivatives JF - Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry N2 - The inversion of the flexible five-membered ring in tetrahydrodicyclopentadiene (TH-DCPD) derivatives remains fast on the NMR timescale even at 103 K. Since the intramolecular exchange process could not be sufficiently slowed for spectroscopic evaluation, the conformational equilibrium is thus inaccessible by dynamic NMR. Fortunately, the spatial magnetic properties of the aryl and carbonyl groups attached to the DCPD skeleton can be employed in order to evaluate the conformational state of the system. In this context, the anisotropic effects of the functional groups in the H-1 NMR spectra prove to be the molecular response property of spatial nucleus independent chemical shifts (NICS). Y1 - 2011 U6 - https://doi.org/10.1039/c0ob00356e SN - 1477-0520 VL - 9 IS - 4 SP - 1098 EP - 1111 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Buchmann, Carsten M. A1 - Schurr, Frank Martin A1 - Nathan, Ran A1 - Jeltsch, Florian T1 - An allometric model of home range formation explains the structuring of animal communities exploiting heterogeneous resources JF - Oikos N2 - Understanding and predicting the composition and spatial structure of communities is a central challenge in ecology. An important structural property of animal communities is the distribution of individual home ranges. Home range formation is controlled by resource heterogeneity, the physiology and behaviour of individual animals, and their intra- and interspecific interactions. However, a quantitative mechanistic understanding of how home range formation influences community composition is still lacking. To explore the link between home range formation and community composition in heterogeneous landscapes we combine allometric relationships for physiological properties with an algorithm that selects optimal home ranges given locomotion costs, resource depletion and competition in a spatially-explicit individual-based modelling framework. From a spatial distribution of resources and an input distribution of animal body mass, our model predicts the size and location of individual home ranges as well as the individual size distribution (ISD) in an animal community. For a broad range of body mass input distributions, including empirical body mass distributions of North American and Australian mammals, our model predictions agree with independent data on the body mass scaling of home range size and individual abundance in terrestrial mammals. Model predictions are also robust against variation in habitat productivity and landscape heterogeneity. The combination of allometric relationships for locomotion costs and resource needs with resource competition in an optimal foraging framework enables us to scale from individual properties to the structure of animal communities in heterogeneous landscapes. The proposed spatially-explicit modelling concept not only allows for detailed investigation of landscape effects on animal communities, but also provides novel insights into the mechanisms by which resource competition in space shapes animal communities. Y1 - 2011 U6 - https://doi.org/10.1111/j.1600-0706.2010.18556.x SN - 0030-1299 VL - 120 IS - 1 SP - 106 EP - 118 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Rocha, Marcia R. A1 - Vasseur, David A. A1 - Hayn, Michael A1 - Holschneider, Matthias A1 - Gaedke, Ursula T1 - Variability patterns differ between standing stock and process rates JF - Oikos N2 - Standing stocks are typically easier to measure than process rates such as production. Hence, stocks are often used as indicators of ecosystem functions although the latter are generally more strongly related to rates than to stocks. The regulation of stocks and rates and thus their variability over time may differ, as stocks constitute the net result of production and losses. Based on long-term high frequency measurements in a large, deep lake we explore the variability patterns in primary and bacterial production and relate them to those of the corresponding standing stocks, i.e. chlorophyll concentration, phytoplankton and bacterial biomass. We employ different methods (coefficient of variation, spline fitting and spectral analysis) which complement each other for assessing the variability present in the plankton data, at different temporal scales. In phytoplankton, we found that the overall variability of primary production is dominated by fluctuations at low frequencies, such as the annual, whereas in stocks and chlorophyll in particular, higher frequencies contribute substantially to the overall variance. This suggests that using standing stocks instead of rate measures leads to an under- or overestimation of food shortage for consumers during distinct periods of the year. The range of annual variation in bacterial production is 8 times greater than biomass, showing that the variability of bacterial activity (e.g. oxygen consumption, remineralisation) would be underestimated if biomass is used. The P/B ratios were variable and although clear trends are present in both bacteria and phytoplankton, no systematic relationship between stock and rate measures were found for the two groups. Hence, standing stock and process rate measures exhibit different variability patterns and care is needed when interpreting the mechanisms and implications of the variability encountered. Y1 - 2011 U6 - https://doi.org/10.1111/j.1600-0706.2010.18786.x SN - 0030-1299 VL - 120 IS - 1 SP - 17 EP - 25 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Donges, Jonathan A1 - Donner, Reik Volker A1 - Rehfeld, Kira A1 - Marwan, Norbert A1 - Trauth, Martin H. A1 - Kurths, Jürgen T1 - Identification of dynamical transitions in marine palaeoclimate records by recurrence network analysis JF - Nonlinear processes in geophysics N2 - The analysis of palaeoclimate time series is usually affected by severe methodological problems, resulting primarily from non-equidistant sampling and uncertain age models. As an alternative to existing methods of time series analysis, in this paper we argue that the statistical properties of recurrence networks - a recently developed approach - are promising candidates for characterising the system's nonlinear dynamics and quantifying structural changes in its reconstructed phase space as time evolves. In a first order approximation, the results of recurrence network analysis are invariant to changes in the age model and are not directly affected by non-equidistant sampling of the data. Specifically, we investigate the behaviour of recurrence network measures for both paradigmatic model systems with non-stationary parameters and four marine records of long-term palaeoclimate variations. We show that the obtained results are qualitatively robust under changes of the relevant parameters of our method, including detrending, size of the running window used for analysis, and embedding delay. We demonstrate that recurrence network analysis is able to detect relevant regime shifts in synthetic data as well as in problematic geoscientific time series. This suggests its application as a general exploratory tool of time series analysis complementing existing methods. Y1 - 2011 U6 - https://doi.org/10.5194/npg-18-545-2011 SN - 1023-5809 VL - 18 IS - 5 SP - 545 EP - 562 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Benmehdi, Sabah A1 - Makarava, Natallia A1 - Benhamidouche, N. A1 - Holschneider, Matthias T1 - Bayesian estimation of the self-similarity exponent of the Nile River fluctuation JF - Nonlinear processes in geophysics N2 - The aim of this paper is to estimate the Hurst parameter of Fractional Gaussian Noise (FGN) using Bayesian inference. We propose an estimation technique that takes into account the full correlation structure of this process. Instead of using the integrated time series and then applying an estimator for its Hurst exponent, we propose to use the noise signal directly. As an application we analyze the time series of the Nile River, where we find a posterior distribution which is compatible with previous findings. In addition, our technique provides natural error bars for the Hurst exponent. Y1 - 2011 U6 - https://doi.org/10.5194/npg-18-441-2011 SN - 1023-5809 VL - 18 IS - 3 SP - 441 EP - 446 PB - Copernicus CY - Göttingen ER - TY - GEN A1 - Nikoloski, Zoran A1 - van Dongen, Joost T. T1 - Modeling alternatives for interpreting the change in oxygen-consumption rates during hypoxic conditions T2 - New phytologist : international journal of plant science KW - hypoxia KW - modeling KW - regulation KW - respiration KW - roots Y1 - 2011 U6 - https://doi.org/10.1111/j.1469-8137.2011.03674.x SN - 0028-646X VL - 190 IS - 2 SP - 273 EP - 276 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Arvidsson, Samuel Janne A1 - Perez-Rodriguez, Paulino A1 - Müller-Röber, Bernd T1 - A growth phenotyping pipeline for Arabidopsis thaliana integrating image analysis and rosette area modeling for robust quantification of genotype effects JF - New phytologist : international journal of plant science N2 - To gain a deeper understanding of the mechanisms behind biomass accumulation, it is important to study plant growth behavior. Manually phenotyping large sets of plants requires important human resources and expertise and is typically not feasible for detection of weak growth phenotypes. Here, we established an automated growth phenotyping pipeline for Arabidopsis thaliana to aid researchers in comparing growth behaviors of different genotypes. The analysis pipeline includes automated image analysis of two-dimensional digital plant images and evaluation of manually annotated information of growth stages. It employs linear mixed-effects models to quantify genotype effects on total rosette area and relative leaf growth rate (RLGR) and ANOVAs to quantify effects on developmental times. Using the system, a single researcher can phenotype up to 7000 plants d(-1). Technical variance is very low (typically < 2%). We show quantitative results for the growth-impaired starch-excessmutant sex4-3 and the growth-enhancedmutant grf9. We show that recordings of environmental and developmental variables reduce noise levels in the phenotyping datasets significantly and that careful examination of predictor variables (such as d after sowing or germination) is crucial to avoid exaggerations of recorded phenotypes and thus biased conclusions. KW - development KW - growth KW - leaf area KW - modeling KW - phenotyping Y1 - 2011 U6 - https://doi.org/10.1111/j.1469-8137.2011.03756.x SN - 0028-646X VL - 191 IS - 3 SP - 895 EP - 907 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Johnson, Kim L. A1 - Lenhard, Michael T1 - Genetic control of plant organ growth JF - New phytologist : international journal of plant science N2 - The growth of plant organs is under genetic control. Work in model species has identified a considerable number of genes that regulate different aspects of organ growth. This has led to an increasingly detailed knowledge about how the basic cellular processes underlying organ growth are controlled, and which factors determine when proliferation gives way to expansion, with this transition emerging as a critical decision point during primordium growth. Progress has been made in elucidating the genetic basis of allometric growth and the role of tissue polarity in shaping organs. We are also beginning to understand how the mechanisms that determine organ identity influence local growth behaviour to generate organs with characteristic sizes and shapes. Lastly, growth needs to be coordinated at several levels, for example between different cell layers and different regions within one organ, and the genetic basis for such coordination is being elucidated. However, despite these impressive advances, a number of basic questions are still not fully answered, for example, whether and how a growing primordium keeps track of its size. Answering these questions will likely depend on including additional approaches that are gaining in power and popularity, such as combined live imaging and modelling. KW - growth coordination KW - organ growth KW - organ identity KW - organ shape KW - organ size Y1 - 2011 U6 - https://doi.org/10.1111/j.1469-8137.2011.03737.x SN - 0028-646X VL - 191 IS - 2 SP - 319 EP - 333 PB - Wiley-Blackwell CY - Malden ER -