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  • 1
    Electronic Resource
    Electronic Resource
    INCREASED HARASSMENT OF RIGHT WHALES (EUBALAENA AUSTRALIS) BY KELP GULLS (LARUS DOMINICANUS) AT PENÍNSULA VALDÉS, ARGENTINA (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 14 (1998), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Kelp gulls at Península Valdés, Argentina, have recently developed the habit of feeding on pieces of skin and blubber that they gouge from the backs of southern right whales. In response, the whales flinch violently, submerge, and swim rapidly away underwater. The level of harassment in 1995 was almost five times higher than when first studied in 1984 by Thomas (1988). In 1995, 67% of attacks were aimed at large white lesions on the whales' backs. The proportion of whales with lesions increased from 0.01 in 1974 to 0.32 in 1990. Mother-calf pairs that were attacked traveled at medium and fast speeds for 3.1 h per day, compared to 0.8 h for undisturbed pairs. Mother-calf pairs are estimated to spend approximately 24% of their daylight hours in states of gullinduced disturbance. Little food is available at Península Valdés, so mothers must rely on blubber reserves to support their calves' growth, behavioral development, and migration to the feeding grounds. Even when undisturbed by gulls, mothers often curtail their calves' play and nursing bouts, suggesting that their energy reserves are limited. Increasingly intense harassment by gulls may therefore compromise calf development and might even induce right whales to abandon Península Valdés for other calving grounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.1998.tb00693.x
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  • 2
    Electronic Resource
    Electronic Resource
    A new variational coupled-electron pair approach to the intermolecular interaction calculation in the framework of the valence bond theory: The case of the water dimer system (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 6204-6210 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A general nonorthogonal coupled-electron pair approach based on the intermediate optimization of virtual orbitals is presented. The resulting procedure, similar to the independent electron pair approximation scheme, is developed in the framework of the valence bond (VB) theory, where the effect of the overlap is directly taken into account. Nonorthogonal virtual orbitals optimal for intermolecular correlation effects were determined starting from the self-consistent field for molecular interaction wave function. These were used in the context of a general ab initio variational multistructure VB wave function consisting of double excitations arising from simultaneous single excitations localized on each monomer. The basis set superposition error is excluded in an a priori fashion and geometry relaxation effects are naturally taken into account. As an application example, the equilibrium structure and binding energy of the water dimer system were determined. The equilibrium oxygen–oxygen distance results to be 2.954 Å, in good agreement with the experimental values (2.946 or 2.952 Å) corrected for anharmonicity of the dimer vibrations. The estimated equilibrium interaction energy is −5.02 kcal/mol, thus comparing favorably with the experimental value of −5.44±0.7 kcal/mol. Taking zero-point vibrational effects into account, the calculated binding enthalpy is −3.22 kcal/mol, in accordance with the experimental estimate of −3.59±0.5 kcal/mol, determined from measures of thermal conductivity of the vapor. The importance of employing basis sets that include diffuse polarization functions in correlated calculations on hydrogen-bonded systems is confirmed. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479925
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  • 3
    Electronic Resource
    Electronic Resource
    A cytologic, immunocytochemical and ultrastructural study of a malignant parotid gland myoepithelioma (1997)
    Oxford, UK : Blackwell Science Ltd
    Cytopathology 8 (1997), S. 0 
    Details
    ISSN: 1365-2303
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2303.1997.41275412.x
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  • 4
    Electronic Resource
    Electronic Resource
    Modification of Guest and Saunders open shell SCF equations to exclude BSSE from molecular interaction calculations (1998)
    Springer
    Theoretical chemistry accounts 99 (1998), S. 358-365 
    Details
    ISSN: 1432-2234
    Keywords: Key words: Basis set superposition error ; Intermolecular interactions ; Restricted open shell Hartree-Fock ; Self-consistent field for molecular interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract. The self-consistent field (SCF) for molecularinteractions algorithm, particularly devised to compute intermolecular interactions, is extended to the case in which one of the two interacting fragments is an open shell system. The method excludes the basis set superposition error in an a priori fashion. To preserve the simplicity of the standard SCF procedure, Guest and Saunders equations concerning the open shell fragment are modified at the cost of a negligible complication with respect to the usual algorithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002140050348
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  • 5
    Electronic Resource
    Electronic Resource
    Epixenosomes, peculiar epibionts of the ciliated protozoonEuplotidium itoi: what kind of organisms are they? (1998)
    Springer
    Protoplasma 201 (1998), S. 38-44 
    Details
    ISSN: 1615-6102
    Keywords: Cellular evolution ; Epixenosomes ; Eukaryotes ; Prokaryotes ; Symbiosis ; In situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Epixenosomes live on the dorsal surface of their ciliate host,Euplotidium itoi. They lack a nuclear envelope and divide like prokaryotes. On the other hand they have a morphological and functional cell compartmentalization and possess tubules that are sensible to tubulin inhibitors and positively react with different antitubulin antibodies. In the present paper, as a first step to investigate their real nature, the in situ hybridization technique was applied at the ultrastructural level. Different prokaryotic and eukaryotic probes suitable for detecting rRNA genes were used. An additional test was performed with the gene encoding for β tubulin in the ciliateEuplotes crassus. Positive results, evidenced by a precise localization of gold particles, were obtained with all the eukaryotic probes used. These probes were obtained from organisms belonging to three different kingdoms (Protista, Animalia, Plantae). On the contrary, no hybridization was obtained with prokaryotic probes, not even when the probe used was an oligonucleotide complementary to all bacterial 16S rRNA so far sequenced. On the basis of these results and of the other observations so far accumulated, the possible eukaryotic nature of epixenosomes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280709
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  • 6
    Electronic Resource
    Electronic Resource
    Implementation of gradient-optimization algorithms and force constant computations in BSSE-free direct and conventional SCF approaches (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 69 (1998), S. 151-158 
    Details
    ISSN: 0020-7608
    Keywords: BSSE ; SCF-MI ; intermolecular interactions ; analytic gradient Hessian ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modification of the Roothaan equations was described in a previous work, which aimed to avoid the BSSE at the Hartree-Fock level of theory. The resulting scheme was called the self-consistent field for molecular interactions (SCF-MI) to underline its special usefulness in the computation of intermolecular interactions. The method provides a complete a priori elimination of the BSSE, while taking into account the natural nonorthogonality of the MOs of the two interacting fragments. Compatibility with the usual formulation of the analytic derivatives of the SCF energy is also guaranteed. This allowed the implementation of gradient-optimization algorithms and force constant matrix computations in both the direct and conventional SCF approaches. The SCF-MI method has been incorporated into the GAMESS-US package. Tests have been performed at the Department of Chemistry of the Iowa State University. Increases in the complication and computation time are minimal if compared to standard SCF codes and the method shows much less basis-set dependence in the predicted molecular properties.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 151-158, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Optimized spin-coupled virtual orbitals (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 225-233 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The goal of obtaining accurate potential energy surfaces for the study of intermolecular forces is of fundamental importance. In this article, we propose a new method to generate a set of virtual orbitals optimized in such a way to give very compact valence bond (VB) wave functions with the same accuracy of very large VB calculations. These optimized virtual orbitals, completely free from BSSE, are developed in the framework of spin coupled theory. Test calculations on the He ··· LiH system are presented together with a comparison with previous studies. © 1996 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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