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  • 1
    ISSN: 1432-0789
    Keywords: Key words Density ; Diversity ; Soil mites ; Agroforestry ; Community structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Populations of soil-dwelling mites were monitored in monoculture plots of four agroforestry tree species, Gliricidia sepium, Leucaena leucocephala, Dactyladenia barteri and Treculia africana, and compared to those in grass and secondary forest plots in the dry season (December 1993 to January 1994) and in the wet season (April to June 1994) in southwest Nigeria. Mite populations were very low in all plots during the dry season (500–3000 m–2), compared to those during the wet season (10 000–30 000 m–2). The highest mite population was observed in Gliricidia plots (3 044 m–2) for the dry season and Leucaena plots (30 240 m–2) for the wet season. Mite genera that were dominant in all the experimental plots were Annectacarus, Haplozetes, Machadobelba, Scheloribates and members of the Galumnidae, Dermanyssidae and Parasitidae. The community structure of mites was similar in the soil for Treculia and Gliricidia plots and for Leucaena and Dactyladenia plots. There were more taxonomic groups of mites under Leucaena than in the other agroforestry plots. Based on the density, diversity and complexity of the mite communities, Leucaena was considered to be better than other agroforestry species in encouraging the growth of mite populations.
    Type of Medium: Electronic Resource
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  • 2
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  83. Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie; 20120516-20120520; Mainz; DOC12hnod563 /20120404/
    Publication Date: 2012-04-05
    Keywords: ddc: 610
    Language: English
    Type: conferenceObject
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Mathematical Economics 23 (1994), S. 323-337 
    ISSN: 0304-4068
    Keywords: Incentives ; Informational efficiency ; Mechanism design ; Public goods ; [jel] C72 ; [jel] D61 ; [jel] D78
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mathematics , Economics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Games and Economic Behavior 7 (1994), S. 441-460 
    ISSN: 0899-8256
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mathematics , Economics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters A 178 (1993), S. 426-430 
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters A 192 (1994), S. 278-284 
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0789
    Keywords: Key words Collembola ; Agroforestry ; Prunings ; Grass ; Litter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The soil- and litter-dwelling Collembola under four agroforestry tree species (Treculia africana, Dactyladenia (Acioa) barteri, Gliricidia sepium and Leucaena leucocephala) were monitored monthly for a period of 12 months and results were compared with those of a secondary forest and a grass plot. Treculia and Dactyladenia produced lower quality litter, leading to lower soil temperature and higher soil moisture under those species, relative to Gliricidia and Leucaena. The agroforestry tree plots contained more soil- and litter-dwelling Collembola than the secondary forest and grass plots. The slowly decomposing litter under Treculia and Dactyladenia supported more litter Collembola than the quickly decomposing litter under Gliricidia and Leucaena. Soil moisture and temperature were, respectively, positively and negatively correlated with populations of soil Collembola. Based on the results of this study, it is suggested that the use of prunings of agroforestry tree species as mulch in agroecosystems would encourage the growth of Collembola populations and enhance their role in decomposition processes.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1106
    Keywords: Key words Respiration ; Cross-correlation ; Bötzinger-complex ; Expiratory neurons ; Decerebrate rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We examined the synaptic connections between pairs of Bötzinger-complex, bulbospinal expiratory neurons in decerebrate rats. All were antidromically activated from the spinal cord at the C2–C3 border. Cross-correlation histograms of 18 ipsilateral pairs showed troughs on both sides of time zero (8) and to one side of time zero (4); most (12) were accompanied by peaks at time zero. Similarly, cross-correlation histograms of the contralateral pairs (12) showed troughs on both sides of time zero (3) and to one side of time zero (3); few (2) were accompanied by peaks at time zero. We considered the troughs in these cross-correlation histograms to be evidence of inhibition between the neurons and sought confirmation of the inhibitory connection. First, using the antidromic activation stimulus, we computed post-stimulus histograms of the extracellularly recorded discharge for six neurons and found that three showed troughs. Then, we continued this approach, computing post-stimulus averages of the membrane potentials recorded intracellularly from these neurons after iontophoresis of chloride to reverse inhibitory synaptic potentials. Depolarising potentials were observed in 15 of 16 of these averages. We interpreted these as reversed inhibitory post-synaptic potentials and concluded that Bötzinger-complex, bulbospinal expiratory neurons inhibit one another in rats as they do in cats.
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  • 9
    ISSN: 1432-1106
    Keywords: Respiration ; Cross-correlation ; Upper cervical inspiratory neurons ; Phrenic and intercostal motoneurons ; Decerebration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We examined the synaptic connections from upper cervical inspiratory neurons to phrenic and intercostal motoneurons in decerebrate rats using cross-correlation. Upper cervical inspiratory neurons (n=79) were recorded from the C1 and C2 segments of the spinal cord in 38 vagotomized, paralyzed, ventilated, and decerebrate rats. The neurons were identified by their inspiratory firing pattern and antidromic activation from the ipsilateral spinal cord at C7. Whole-nerve recordings were made using bipolar electrodes from the central cut ends of the C5 phrenic nerve and the external and internal intercostal nerves at various thoracic levels. Cross-correlation histograms were computed between these recordings to detect short time-scale synchronizations indicative of synaptic connections. The 55 cross-correlation histograms computed between the upper cervical inspiratory neurons and the ipsilateral phrenic nerve showed seven (13%) narrow peaks (mean half-amplitude width±SD, 1.09±0.15 ms) at short latencies (mean latency±SD, 1.29±0.26 ms) suggestive of monosynaptic excitation, and four (7%) broader peaks (mean half-amplitude width±SD, 1.50±0.17 ms) at short latencies (mean latency±SD, 1.40±0.24 ms) suggestive of oligosynaptic excitation. Another 14 (25%) cross-correlation histograms displayed a central broad peak (mean half-amplitude width±SD, 1.59±0.23 ms) suggestive of common activation. The eight cross-correlation histograms computed between the upper cervical inspiratory neurons and the contralateral phrenic nerve were featureless. The 77 cross-correlation histograms computed between the upper cervical inspiratory neurons and the internal and external intercostal nerves at various thoracic levels (T2–8) showed no peaks suggestive of synaptic connections. We conclude that some upper cervical inspiratory neurons make monosynaptic and paucisynaptic connections to phrenic motoneurons but not to intercostal motoneurons.
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  • 10
    ISSN: 1432-1106
    Keywords: Key words Respiration ; Ventral-group ; bulbospinal inspiratory neurons ; Cross-correlation ; Spike-triggered averaging ; Decerebrate rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We examined the synaptic connections between ventral-group, bulbospinal inspiratory neurons in 27 vagotomized, paralyzed, ventilated, and decerebrated rats using cross-correlation and spike-triggered averaging of intracellular potentials. The neurons were recorded in the medulla about the level of the obex and identified by their inspiratory firing pattern and antidromic activation from the spinal cord at C7. Whole C5 phrenic nerve recordings were made using bipolar electrodes from the central cut ends of the nerve. Most (108/137, 79%) inspiratory neurons discharged only during inspiration but some (29/137, 21%) also discharged during early expiration. Their intracellular membrane potentials displayed a pattern of depolarization during inspiration, repolarization during early expiration, and hyperpolarization during late expiration. Intracellular chloride iontophoresis changed the inspiratory membrane potential trajectories from augmenting to decrementing in 11 of 19 neurons tested (58%), and demonstrated the presence of both early-decrementing and late-augmenting waves of inhibitory postsynaptic potentials during expiration in 11 of 19 neurons tested (58%). Cross-correlation histograms were computed between pairs of extracellularly recorded neurons to detect short time scale synchronizations indicative of synaptic connections (26 ipsilateral; 23 contralateral). While none of the cross-correlation histograms for contralateral pairs showed peaks, most (23, 88%) of those for ipsilateral pairs showed peaks (mean half-amplitude width ± SD = 1.3 ± 0.4 ms) at time zero suggestive of common activation. Some of the latter (6, 23%) showed troughs superimposed on the central peaks (mean half-amplitude width ± SD = 0.9 ± 0.2 ms) at short latencies (mean latency ± SD = 1.8 ± 1.9 ms) suggestive of inhibition; others (8, 31%) had asymmetrical central peaks and two had bilateral peaks suggesting more complex interconnections. Averages of intracellular membrane potentials of inspiratory neurons (n = 24), triggered by action potentials of a nearby extracellularly recorded inspiratory neuron, were computed to detect synchronized postsynaptic potentials. Over half (16, 67%) showed postsynaptic potentials (mean amplitude ± SD = 201 ± 176 μV; mean half-amplitude width ± SD = 2.3 ± 0.8 ms) confirming the cross-correlation findings of common excitation. We conclude that in decerebrated rats, ventral-group inspiratory neurons projecting to the C7 spinal segment share powerful, ipsilaterally distributed excitatory inputs which enhance their synchronous activity during inspiration. They also receive inhibition during inspiration and early-decrementing and late-augmenting inhibitory inputs during expiration.
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