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  • 1
    Electronic Resource
    Electronic Resource
    Nitric oxide synthase-containing projections to the ventrobasal thalamus in the rat (1999)
    Springer
    Anatomy and embryology 200 (1999), S. 265-281 
    Details
    ISSN: 1432-0568
    Keywords: Key words Retrograde axonal transport ; Somatosensory system ; Pedunculopontine nucleus ; Laterodorsal tegmental nucleus ; Cholinergic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Microiontophoretic studies of thalamic neurons suggests that nitric oxide (NO) plays an important role in mediating somatosensory transmission. The thalamus contains few nitric oxide synthase (NOS)-immunoreactive neurons; thus, the major source of thalamic NO is presumably from NOS-positive axons of extrathalamic origin. The cells of origin of these putative NOS-containing pathways to the ventrobasal thalamus were investigated in rats by combining retrograde tracing with immunocytochemistry for NOS. The location and morphology of double-labeled neurons was compared with that of single-labeled neurons. The most significant sources of NOS-containing afferents to the thalamus were found to be the pedunculopontine (PPN) and laterodorsal tegmental (LDT) nuclei. NOS-immunoreactive neurons in these cholinergic nuclei project bilaterally to the thalamus, most strongly ipsilaterally. The thalamus appears to be a major target of PPN, since even selective thalamic injections result in retrograde labeling of at least one third of its NOS-immunoreactive neurons. A significant number of NOS-negative neurons in both the PPN and LDT also project to the thalamus. Minor sources of NOS-containing thalamic afferents include the lateral hypothalamus, the dorsal, median and pontine raphe nuclei, the parabrachial nuclei, and the pontomedullary reticular formation. In all these structures, NOS-negative thalamopetal neurons greatly outnumber the NOS-positive ones. Ascending sensory pathways to the thalamus, including those from the sensory trigeminal nuclei, the dorsal column nuclei, and the spinal cord, as well as the auditory and vestibular centers, arise exclusively from NOS-negative neurons. The major NOS-positive projections are implicated in affective and alerting systems, supporting that NO may act to modulate attentiveness in thalamic relay nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050278
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  • 2
    Electronic Resource
    Electronic Resource
    Monte Carlo study of core–valence separation schemes (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 2873-2885 
    Details
    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
    URL: http://dx.doi.org/10.1063/1.475675
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  • 3
    Electronic Resource
    Electronic Resource
    Satiation-dependent, intra-cohort variations in prey size selection of young roach (Rutilus rutilus) (1999)
    Springer
    Oecologia 121 (1999), S. 499-505 
    Details
    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
    URL: http://dx.doi.org/10.1007/s004420050956
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    Paper (German National Licenses)
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