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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 2873-2885 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: All-electron partitioning of wavefunctions into products ΨcoreΨval of core and valence parts in orbital space results in the loss of core-valence antisymmetry, uncorrelation of motion of core and valence electrons, and core–valence overlap. These effects are studied with the variational Monte Carlo method using appropriately designed wavefunctions for the first-row atoms and cations. It is shown that the loss of antisymmetry with respect to an interchange of core and valence electrons is a dominant effect which increases rapidly through the row, while the effect of decorrelating the core and valence electrons is significantly smaller. Orthogonality of the core and valence parts partially substitutes the exclusion principle and is absolutely necessary for meaningful calculations with partitioned wavefunctions. Core–valence overlap may lead to nonsensical values of the total energy. Even relatively crude core–valence partitioned wavefunctions generally can estimate ionization potentials and electron affinities with better accuracy than that of the traditional, non-partitioned ones, provided that they achieve maximum separation (independence) of core and valence shells accompanied by high internal flexibility of Ψcore and Ψval. Our best core–valence partitioned wavefunction of that kind estimates the ionization potentials with an accuracy comparable to the most accurate theoretical determinations in the literature. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 2489-2495 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An improved density matrix functional (DMF) combining the properties of the "corrected Hartree" (CH) and "corrected Hartree–Fock" (CHF) approximations is proposed. Functionals of the CH/CHF type and the closely related natural orbital functional of Goedecker and Umrigar (GU) are tested in fully variational finite basis set calculations of light atoms, the lowest energy singlet methylene, and, for the first time, potential energy curves of diatomic molecules. Although CH/CHF-style DMFs may give reasonable energies for atoms and molecules near equilibrium geometries, they predict unrealistically shallow minima in the potential energy curves for diatomic molecules with more than two electrons. The calculated CH and CHF molecular dissociation curves exhibit the same patterns of over- and under-correlations as the corresponding correlation energy plots for the homogeneous electron gas undergoing a transition from high to low densities. In contrast, the GU functional yields not only accurate atomic and molecular energies but also plausible dissociation curves. The reasons behind the observed performance are analyzed. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1600-0560
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract:  Claudins are a family of transmembrane proteins involved in cell-to-cell adhesion and are believed to be the main component of tight junctions. Recent studies have suggested that some metastatic solid tumors lack claudin expression. It is unknown whether claudins play a role in cutaneous melanoma. Immunohistochemical studies were performed on tissue microarrays containing 19 benign melanocytic nevi (BN), 21 dysplastic nevi (DN), 23 primary malignant melanomas (MMs), and 31 metastatic melanomas (MMMs) using a polyclonal anti-claudin-1 antibody. Immunoreactivity in tumor cells and associated vessels was graded by intensity and by percentage of reactive cells. Normal epidermis served as internal control (3+ labeling). Cases with at least 2+ labeling in more than 25% of the cells were considered positive. Claudin-1 expression was present in 37% of BN, 24% of DN, 26% of MM, and 3.2% of MMM. Tumor-associated vessels showed the following results: 11 of 19 (58%) in BN, 14 of 21 (67%) in DN, 17 of 23 (74%) in MM, and 6 of 31 (19%) in MMM. A significant loss of expression was noted between MMM and all other lesions in tumor cells and associated vessels. There was no significant difference between BN, DN, and MM. Within primary melanomas, there was a significant correlation between expression of claudin in tumor cells and Clark level/Breslow thickness. Also significant was a decreased expression of claudin in tumor vessels of lesions with higher Breslow thickness or Clark level. These data suggest that loss of claudin-1 may play a significant role in the acquisition of metastatic phenotype in cutaneous melanoma.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Journal of cutaneous pathology 29 (2002), S. 0 
    ISSN: 1600-0560
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Fascin containing actin bundles provide mechanical support to cellular protrusions and stress fibers. In cancers, some malignant cells (e.g. subsets of breast and ovarian carcinomas) express fascin. In skin cancer, the role of fascin is unknown.Methods:  Cases of 61 keratocytic neoplasms, 35 melanocytic neoplasms, nine extramammary Paget's disease (four with adenocarcinoma) and five sarcomas (angiosarcoma and atypical fibroxanthoma) were examined by immunohistochemistry, using monoclonal antihuman fascin antibody, clone 55 k-2 (Dako Corporation, Carpinteria, CA, USA).Results:  Fascin labeled all sarcomas and all keratinocytic neoplasms except for pagetoid pattern Bowen's disease. The regions of most intense fascin labeling were seen in the basal cells of infiltrative tumor margins. A minority of Merkel cell carcinomas exhibited weak or absent immunoreactivity. All melanocytic nevi except for some junctional nests of dysplastic melanocytic nevi expressed fascin. However, pagetoid cells of melanoma in situ and epithelioid cells of invasive melanoma weakly expressed or did not express fascin, whereas melanoma cells exhibiting spindle cell morphologies labeled intensely with fascin. Lastly, all cells of extramammary Paget's disease and most associated adenocarcinomas cells did not or were faintly labeled by fascin antibodies. Decreased or absent fascin expression was significantly associated with skin cancers with a high risk for metastasis (e.g. melanoma) vs. those with a low risk (e.g. basal cell carcinoma) (24% vs. 100% with 〉 50% immunoreactivity; p = 0.0001, chi-squared test).Conclusion:  Fascin is expressed by skin tumors that locally infiltrate and replace surrounding tissues indicating a role for fascin in cell adhesion, cell motility and invasiveness. No or weak fascin expression is exhibited by cancers with pagetoid intraepidermal spread and by invasive tumors with a high risk of metastasis. Downregulation or loss of fascin's actin-bundling properties, probably associated with disorganization of cell–cell and cell–matrix contacts, may be a crucial step in the progression from locally invasive to widely disseminating cancers.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1939
    Keywords: Key words Prey profitability ; Predator size ; Foraging strategy ; Daphnia magna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Feeding rate and behaviour of juvenile roach in a non-depleting patch consisting of Daphnia magna of two size classes (optimal and much smaller) were studied in 20-min experiments. The medium size group (standard length 26–28 mm), large (28–32 mm), and small (24–26 mm) fish differed significantly in the proportion of small prey eaten. During a short initial period of burst feeding (1–5 min) only large prey were selected by all fish. The switch from large to small prey occurred much earlier in small than in large roach. During the initial period small fish had higher feeding rates. In small fish, small prey made up about 30% of the food biomass consumed during the whole 20-min feeding period, whereas in large fish small prey played a minor role (about 2%). Within the medium-sized group, one subgroup of fish, characterized by early switching to small prey, showed a feeding behaviour similar to small fish, whereas the other subgroup, which switched later, behaved like large fish. Neither the apparent prey size model nor optimal foraging theory, even in its dynamic version, were supported by the data. It is suggested that vigilance against predators changes the initial energy-maximizing strategy in hungry fish to a time-minimizing strategy in partially satiated fish. Intra-cohort variations in prey size selection might be related to social status of the fish. Social status may affect prey size selection and feeding rate, and thus result in different growth rates and size differentiation.
    Type of Medium: Electronic Resource
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  • 6
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    Berlin, etc. : Periodicals Archive Online (PAO)
    Philologus. 116:1 (1972) 139 
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  • 7
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    Berlin, etc. : Periodicals Archive Online (PAO)
    Philologus. 116:2 (1972) 167 
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  • 8
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    Unknown
    Berlin, etc. : Periodicals Archive Online (PAO)
    Philologus. 131:2 (1987) 165 
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  • 9
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    Unknown
    Berlin, etc. : Periodicals Archive Online (PAO)
    Philologus. 131:2 (1987) 309 
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  • 10
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    Unknown
    Berlin : Periodicals Archive Online (PAO)
    Klio. 64:2 (1982) 313 
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