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  • 1
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    Antiproton-proton annihilation at rest into two-body final states (1993)
    Springer
    Details
    Publication Date: 1993-06-01
    Print ISSN: 0170-9739
    Electronic ISSN: 1431-5858
    Topics: Physics
    Published by Springer
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Ornibactins—a new family of siderophores from Pseudomonas (1993)
    Springer
    BioMetals 6 (1993), S. 93-100 
    Details
    ISSN: 1572-8773
    Keywords: iron ; ornibactin ; Pseudomonas ; pyoverdines ; siderophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Novel linear hydroxamate/hydroxycarboxylate siderophores from strains of Pseudomonas cepacia were isolated and named ornibactins. The ornibactins represent modified tetrapeptide siderophores, possessing the sequence l-Orn1(N δ-OH, N Δ-acyl)-d-threo-Asp(β-OH)-l-Ser-l-Orn4(N δ-OH, N δ-formyl)-1,4-diaminobutane. The N δ-acyl groups of Orn1(N δ-OH, N δ-acyl) may vary and represent the three acids 3-hydroxybutanoic acid, 3-hydroxyhexanoic acid and 3-hydroxyoctanoic acid, leading to a mixture of three different ornibactins, designated according to their acyl chain length as ornibactin-C4, ornibactin-C6 and ornibactin-C8. Each of the siderophores is accompanied by a small amount of a more hydrophilic component with a 16 a.m.u. higher mass. The structure elucidation was based on results from gas chromatography amino acid analysis, electrospray mass spectrometry, and one- and two-dimensional nuclear magnetic resonance techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00140109
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  • 3
    Electronic Resource
    Electronic Resource
    Spherical containment and the Minkowski dimension of partial orders (1993)
    Springer
    Order 10 (1993), S. 227-237 
    Details
    ISSN: 1572-9273
    Keywords: 06A06 ; 52A37 ; Causal order ; spherical (containment) order ; Minkowski dimension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The recent work on circle orders generalizes to higher dimensional spheres. As spherical containment is equivalent to causal precedence in Minkowski space, we define the Minkowski dimension of a poset to be the dimension of the minimal Minkowski space into which the poset can be embedded; this isd if the poset can be represented by containment with spheresS d−2 and of no lower dimension. Comparing this dimension with the standard dimension of partial orders we prove that they are identical in dimension two but not in higher dimensions, while their irreducible configurations are the same in dimensions two and three. Moreover, we show that there are irreducible configurations for arbitrarily large Minkowski dimension, thus providing a lower bound for the Minkowski dimension of partial orders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01110544
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  • 4
    Electronic Resource
    Electronic Resource
    Spectral responses, including a UV-sensitive cell type, in the eye of the isopodLigia exotica (1993)
    Springer
    Naturwissenschaften 80 (1993), S. 233-235 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01175741
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  • 5
    Electronic Resource
    Electronic Resource
    Seasonality of circadian locomotor activity in an insect (1993)
    Springer
    Journal of comparative physiology 171 (1993), S. 713-724 
    Details
    ISSN: 1432-1351
    Keywords: Circadian rhythms ; Seasonality ; Locomotor activity ; Carabid beetles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Daily periodic locomotor activity of Carabus auronitens was recorded in a climate-constant laboratory with the animals exposed to naturally changing photoperiods. Most actograms exhibit directed seasonal variations of duration and phase position of daily activity. Seasonal locomotor activity starts in early spring (following dormancy) on a low daily level, first being confined to a short time span around dusk (and even shorter around dawn). In the course of season, the daily onsets of activity become closely related with sunset and the duration of daily activity is steadily extended with both parts of the bimodal phase fusing to a common, unimodal activity band by late spring. Subsequently, it is further extended into forenoon, until in summer (shortly before aestivation), spontaneous phase inversion turns activity periodicity from nocturnality into diurnality within 1 day. Such seasonal variations are paralleled by changes in the precision of synchronization of the individuals' activity rhythms to the entraining light/dark cycle. No geographical differences were detected. The results support the idea of the circadian clock as a system of two dynamically coupled physiological oscillators that invert their phase relation as soon as the natural dark phase falls short of some minimum-tolerable night length.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213068
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  • 6
    Electronic Resource
    Electronic Resource
    Functional and morphological regeneration of olfactory tracts and subtracts in goldfish (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 91-99 
    Details
    ISSN: 1432-1351
    Keywords: Regeneration ; Olfactory tract ; Behaviour ; Morphology ; Goldfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Goldfish are ideal vertebrates for the study of regeneration within the central nervous system. The present behavioural and neuroanatomical investigations after bilateral transection of the entire olfactory tracts of either lateral or medial subtracts have been designed (1) to examine the relationship between morphological changes and changes in the perception of spontaneously preferred chemosensory stimuli, (2) to investigate the animals' ability to qualitatively discriminate amino acids in olfactory concentrations (below taste threshold, 10-6–10-8 M), one of which had been rewarded preoperatively (“specific” regeneration), and (3) to examine the discriminative ability for amino acids at concentrations above taste threshold (〉 10-5 M) in intact sham-operated, and in operated specimens at various time intervals before functional regeneration. Within 10–14 days after bilateral transection of the lateral olfactory tracts, specific regeneration was observed. After bilateral transection of the medial olfactory tracts, no immediate behavioural change was recorded for 1 week. Thereafter, goldfish behaviour became unstable and dropped to the chance level for 3–4 weeks. Subsequent to this time the goldfish returned to the preoperative level. Following bilateral crushing of the olfactory tracts and after total tractotomy, a specific regeneration was observed after 4 weeks and 6–8 weeks, respectively, post op. HRP studies showed that after bilateral lesioning a qualitative reinnervation of the respective nuclei within the forebrain by the medial and lateral olfactory subtracts was evident.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214718
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  • 7
    Electronic Resource
    Electronic Resource
    Feeding effects on daily locomotor activity in Carabus auronitens (1993)
    Springer
    Journal of comparative physiology 173 (1993), S. 49-55 
    Details
    ISSN: 1432-1351
    Keywords: Circadian rhythms ; Feeding effects ; Locomotor activity ; Ground beetles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Effects of food supply on daily periodic locomotor activity in the ground beetle Carabus auronitens were recorded in the laboratory with the animals exposed to natural daylight and photoperiod. Inspection of individual actograms exhibits that in most cases feeding leads to strongly reduced and more or less irregularly distributed activity for a period of up to 4 days. In terms of quantitative parameters, the animals respond to food supply by an immediate reduction of mean amounts of daily activity. This is achieved through the reduction of duration (as a consequence of reduced burstlengths instead of burstnumber) and, less distinctly, the reduction of intensity. The initial levels of parameters are reattained after 4 days. Direct comparison by means of standardized (i.e. level-independent) relative parameter functions demonstrates close concordance between the amount and duration of daily activity; however, distinct synchronous change of intensity is apparent as a consequence of food supply only. This means that any variation of activity amounts is due to changing duration rather than to intensity variation. In analogy to the feeding-dependent parameter dynamics, also the proportion of animals with strong synchronization to the natural light/dark cycle is considerably reduced by food supply. The feeding-dependent reduction of activity is paralleled by temporarily reduced activity of proteolytic enzymes in the beetles. It is argued that, for the purpose of energy saving, the animals will remain inactive as long as reduced enzyme activity inhibits further consumption and digestion of food.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209617
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  • 8
    Electronic Resource
    Electronic Resource
    Rhythmicity of chromophore turnover of visual pigment in the Antarctic amphipod Orchomene plebs (Crustacea; Amphipoda) (1993)
    Springer
    Journal of comparative physiology 173 (1993), S. 615-619 
    Details
    ISSN: 1432-1351
    Keywords: Photoreception ; Circadian rhythms ; Visual pigment ; Antarctica ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. Relative retinal amounts in the compound eye of the Antarctic amphipod Orchomene plebs were assessed during conditions of continuous summer daylight every 3 h over a period of 48 h. The habitat of the experimental animal is the bottom of the Ross Sea (78°S; 166°E) down to depths of at least 400 m; water temperature is a constant — 1.8° C. A periodicity of 12 h was detected with relative amounts of 11-cis retinal exhibiting peaks at midday and at midnight and troughs at 7.00 h and 19.00 h. 2. The result that 90% of retinoid were insoluble in n-hexane suggests that at least 90% of the measured retinoid were attached to membrane-bound proteins such as opsin. 3. Selective light adaptation showed that the visual pigments were thermostable and photoregenerable. The main absorbance peak of rhodopsin, compared with metarhodopsin, seems to be in the longer wavelengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197769
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  • 9
    Electronic Resource
    Electronic Resource
    A convenient semisynthetic route to hypericin (1993)
    Springer
    Monatshefte für Chemie 124 (1993), S. 339-341 
    Details
    ISSN: 1434-4475
    Keywords: Emodin ; Emodin anthrone ; Hypericin ; Cortex frangulae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine semisynthetische Route zur Darstellung von Hypericin unter Verwendung vonCortex frangulae als Ausgangsmaterial wurde erarbeitet. Das daraus einfach und in guten Ausbeuten isolierte Emodin wurde mit Hilfe von SnCl2 zu Emodinanthron reduziert. Letzteres wurde dann über eine bekannte oxidative Dimerisierung und Photocyclisierung zu Hypericin umgesetzt.
    Notes: Summary A semisynthetic route to produce hypericin was established usingCortex frangulae as the starting point. The emodin isolated from it easily and in good yield was reduced to emodin anthrone by means of SnCl2. The latter was reacted via a known oxidative dimerization and photocyclization reaction into hypericin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810594
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  • 10
    Electronic Resource
    Electronic Resource
    Longitudinal patterns of dissolved organic carbon concentration and suspended bacterial density along a blackwater river (1993)
    Springer
    Biodegradation 21 (1993), S. 73-93 
    Details
    ISSN: 1572-9729
    Keywords: blackwater rivers ; DOC ; molecular weight fractions ; floodplains ; humic rivers ; longitudinal changes ; suspended bacterial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dissolved organic carbon (DOC) is the dominant form of carbon in transport in blackwater rivers, and bacteria are the major biological agents of its utilization. This study describes longitudinal patterns in DOC concentration and relates them to suspended bacterial populations in the channel. Concentrations of total DOC, three molecular weight fractions, and bacterial numbers were determined at 12 sites along the Ogeechee River in 1985–1986 and 1989 during periods of low and high discharge. Suspended bacterial populations were compared with DOC concentrations to determine if differences in bacterial abundance were related to longitudinal patterns of DOC concentration. Three distinct longitudinal patterns were observed: (1) The longitudinal pattern followed by both total and intermediate molecular weight DOC concentrations was a linear function of the geographic distance along the river. (2) During low flow conditions, there was a high degree of correspondence between patterns of bacterial numbers and low MW DOC (〈 1000 apparent MW). (3) During periods of high discharge, the proportion of high (〉 10,000) and intermediate (1000–10,000) MW fractions increased, and there was no longer a clear relationship between bacterial cells and low MW DOC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00000872
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