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  • 1
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    Spatial heterogeneity in species composition constrains plant community responses to herbivory and fertilisation (2018)
    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Ecology Letters, WILEY-BLACKWELL PUBLISHING, 21(9), pp. 1364-1371, ISSN: 1461-023X
    Details
    Publication Date: 2018-11-09
    Description: Environmental change can result in substantial shifts in community composition. The associated immigration and extinction events are likely constrained by the spatial distribution of species. Still, studies on environmental change typically quantify biotic responses at single spatial (time series within a single plot) or temporal (spatial beta diversity at single time points) scales, ignoring their potential interdependence. Here, we use data from a global network of grassland experiments to determine how turnover responses to two major forms of environmental change – fertilisation and herbivore loss – are affected by species pool size and spatial compositional heterogeneity. Fertilisation led to higher rates of local extinction, whereas turnover in herbivore exclusion plots was driven by species replacement. Overall, sites with more spatially heterogeneous composition showed significantly higher rates of annual turnover, independent of species pool size and treatment. Taking into account spatial biodiversity aspects will therefore improve our understanding of consequences of global and anthropogenic change on community dynamics.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 2
    Electronic Resource
    Electronic Resource
    The Absolute Configuration of trans-2,6-Dimethylpiperidine1 (1966)
    s.l. : American Chemical Society
    The @journal of organic chemistry 31 (1966), S. 3451-3452 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo01348a537
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  • 3
    Electronic Resource
    Electronic Resource
    Exploratory shock-wave study of thermal nitrogen trifluoride decomposition and reactions of nitrogen trifluoride and dinitrogen tetrafluoride with hydrogen (1973)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 77 (1973), S. 2823-2830 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100642a001
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Large-order dimensional perturbation theory for two-electron atoms (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 8481-8496 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An asymptotic expansion for the electronic energy of two-electron atoms is developed in powers of δ=1/D, the reciprocal of the Cartesian dimensionality of space. The expansion coefficients are calculated to high order (∼20 to 30) by an efficient recursive procedure. Analysis of the coefficients elucidates the singularity structure in the D→∞ limit, which exhibits aspects of both an essential singularity and a square-root branch point. Padé–Borel summation incorporating results of the singularity analysis yields highly accurate energies; the quality improves substantially with increase in either D or the nuclear charge Z. For He, we obtain 9 significant figures for the ground state and 11 for the 2p2 3Pe doubly excited state, which is isomorphic with the ground state at D=5 by virtue of interdimensional degeneracy. The maximum accuracy obtainable appears to be limited only by accumulation of roundoff error in the expansion coefficients. The method invites application to systems with many electrons or subject to external fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463419
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  • 5
    Electronic Resource
    Electronic Resource
    Rates of convergence of the partial-wave expansions of atomic correlation energies (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 4484-4508 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The coefficients of the leading terms of the partial-wave expansion of atomic correlation energies in powers of (l+1/2)−1 are derived for the second- and third-order perturbed energies in the 1/Z expansion for all possible states of two-electron atoms, and for second-order Møller–Plesset (many-body perturbation) theory for arbitrary n-electron atoms. The expressions for these coefficients given in Table I involve simple integrals over the zeroth-order wave functions (for the third order energies first-order wave functions are also involved). The leading term of E(2) goes as (l+1/2)−4 for natural parity singlet states, as (l+1/2)−6 for triplet states, and as (l+1/2)−8 for unnatural parity singlet states. There are no odd powers of (l+1/2)−1 present in E(2), and the coefficient of the (l+1/2)−6 term for natural parity singlet states of two-electron systems in the 1/Z expansion is generally −5/4 times the coefficient of the (l+1/2)−4 term. In E(3) there are terms that go as odd powers of (l+1/2)−1; the leading term is expressible in terms of the zeroth-order wave function and goes as (l+1/2)−5 for natural parity singlet states, as (l+1/2)−7 for triplet states, and as (l+1/2)−9 for unnatural parity singlet states. Numerical values of the coefficients for E(2) in two-electron atoms are given in Table II. The relation of our results to those obtained by Hill for variational calculations on the He ground state is discussed and generalizations of Hill's formulas are conjectured. The unexpected results for unnatural parity singlet states are traced back to the behavior of their wave functions at the point of coalescence of two electrons. In terms of the relative coordinate of the two electrons they represent d waves, in contrast to s waves for natural parity singlet states and p waves for triplet states of either parity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462811
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  • 6
    Electronic Resource
    Electronic Resource
    Comment on: Deuterium nuclear fusion at room temperature: A pertinent inequality on barrier penetration (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 6115-6117 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Gerald Rosen (Ref. 1) claims to justify the large value apparently observed by Fleischman and Pons and also by Jones et al., in their experiments on cold fusion. Rosen derives an inequality for the Coulomb barrier penetration factor. This comment points out a crucial error in his derivation. (AIP)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458981
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  • 7
    Electronic Resource
    Electronic Resource
    Guiding-function optimization in biased-selection Monte Carlo calculations (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 8407-8414 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We show that the guiding function, which is used to generate the Monte Carlo integration points in a biased-selection calculation, can be optimized so as to minimize the statistical error of an expectation value. For excited states we introduce an orthogonalizing part into the minimization functional to prevent ground and excited states from mixing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463410
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  • 8
    Electronic Resource
    Electronic Resource
    The calculation of exchange forces: General results and specific models (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 2841-2854 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to clarify questions about the calculation of the exchange energy of a homonuclear molecular ion, an analysis is carried out of a model problem consisting of the one-dimensional limit of H2+. It is demonstrated that the use of the infinite polarization expansion for the localized wave function in the Holstein–Herring formula yields an approximate exchange energy which at large internuclear distances R has the correct leading behavior to O(e−R) and is close to but not equal to the exact exchange energy. The extension to the n-dimensional double-well problem is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465193
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  • 9
    Electronic Resource
    Electronic Resource
    Position Paper of the American Council on Science and Health on Risk Factors for Breast Cancer: Established, Speculated, and Unsupported (1998)
    Oxford, UK : Blackwell Science Inc
    The @breast journal 4 (1998), S. 0 
    Details
    ISSN: 1524-4741
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: This article provides the position of the American Council on Science and Health regarding how breast cancer is defined and classified; the magnitude of the public health problem of breast cancer among women; the implications of variation in incidence of breast cancer internationally and with migration; access to health care as a factor in slight differences in incidence and mortality rates among African-American and white women; and the evidence concerning various proposed human-breast-cancer risk factors. The article classifies risk factors as either established, speculated, or unsupported on the basis of available evidence.Specific genes have been identified that may explain as much as 5–10% of new breast cancer cases. Inherited predispositions may be characterized by family history of breast or ovarian cancer, young age at diagnosis, breast cancer diagnosed in both breasts, and male breast cancer. Benign breast disease (BBD), particularly the subtypes of BBD involving atypical hyperplasia, and exposure early in life to ionizing radiation is an established risk factor for breast cancer. Several reproductive characteristics are established as risk factors for breast cancer: early age at menarche, first full-term pregnancy after age 35 years of late age, and late age of menopause. Obesity and low physical activity are established as risk factors for breast cancer and are modifiable.Speculated risk factors for breast cancer that are gaining scientific support include nulliparity, oral contraceptive use, and postmenopausal estrogen replacement therapy. Speculated risk factors for which there is conflicting or preliminary support include not breast feeding, postmenopausal estrogen/progestogen replacement therapy, prescribed diethylstilbestrol, low consumption of phytoestrogens, specific dietary practices, alcohol consumption, not using nonsteroidal antinflammatory drugs, abortion, and breast augmentation. Unsupported risk factors include higher than average consumption of phytoestrogens, premenopausal obesity, electromagnetic fields, and low-dose ionizing radiation after 40 years of age. There is only limited support for xenoestrogens and large breast size as risk factors for breast cancer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1524-4741.1998.430177.x
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  • 10
    Electronic Resource
    Electronic Resource
    Radiofrequency Ablation of Idiopathic Left Ventricular Tachycardia at the Site of Earliest Activation as Determined by Noncontact Mapping (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 11 (2000), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Ablation of Idiopathic LV Tachycardia. Introduction. The most effective method for guiding radiofrequency (RF) ablation of idiopathic left ventricular tachycardia (ILVT) has yet to be determined. We investigated the use of noncontact mapping in five patients with this condition.Methods and Results. The multielectrode array was positioned in the left ventricular apex via the retrograde approach. Isopotential color maps of ILVT were examined to determine the site of earliest endocardial activation. The ablation catheter was steered to the target site using the locator signal. Pace mapping was performed and contact electrograms examined for diastolic potentials. RF energy was applied to the target site. Sustained ventricular tachycardia was induced in 2 patients and nonsustained ventricular tachycardia in 3. The site of earliest activation was at the apical Septum in 3. the inferior apex in I, and the base of the inferior wall in 1. Mean timing was 21 ± 10) msec before onset of the surface QRS. Diastolic activity was visualized with noncontact mapping at the base of the septum in 1 patient. A Purkinje potential was seen at the ablation site in only 1 patient. No diastolic activity was seen in the remaining 3 patients. Tachycardia was successfully terminated in all 5 patients with a median of four RF applications. No patient suffered a recurrence after 9.6 ± 4.7 months of follow-up.Conclusion. By identifying the precise site of earliest activation during ILVT, noncontact mapping has been shown to be an effective and safe method for guiding RF ablation. (J Cardiovasc Electrophysiol Vol. 11. pp 1094-1101. October 2000)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.2000.tb01754.x
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