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  • 1
    Electronic Resource
    Electronic Resource
    Untersuchungen über die Ermüdungen des Sehens an Gesunden und Nervenkranken (1937)
    Springer
    Journal of neurology 144 (1937), S. 141-159 
    Details
    ISSN: 1432-1459
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung 1. Es wird eine Versuchsanordnung beschrieben, mit der es gelingt, die Schwankungen der Lichtempfindlichkeit über längere Zeit im Dunkelversuch zu messen. 2. Es sind kurzfristige Versuche zur Erfassung der Änderung ungeeignet. Versuche über 1/2 Stunde mit minutlicher Ablesung sind am günstigsten. 3. Man findet normal eine geringe Schwankungsbreite der Empfindlichkeit. Sie beträgt in unseren Versuchen bis zum Doppelten der tiefsten Schwelle. 4. Bei körperlicher Ermüdung erhöht sich die Schwankungsbreite wenig. 5. Bei 30 untersuchten Nervenkranken findet sich teilweise eine viel stärkere Schwankung der Lichtempfindlichkeit. Sie kann bis zum 40fachen des tiefsten Punktes ansteigen. 6. Es gelingt mit dem Verfahren nicht, die Lokalisation der Ermüdung anzugeben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01761896
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Partial characterization of chitin degrading enzymes from two euphausiids, Euphausia superba and Meganyctiphanes norvegica (1988)
    Springer
    Polar biology 9 (1988), S. 115-122 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chitinase and N-acetyl-β-D-glucosaminidase have been demonstrated in Meganyctiphanes norvegica and in Euphausia superba and partly characterized. The enzymes from both species have broad pH-optima (maxima around pH 5.0) and temperature optima between 40 and 50°C. The enzymes are relatively stable; even at about 45°C half of the enzyme activity is retained after 30 min incubation. The presence of fluoride does not affeet enzymatic activity. Chitinase activity appears in three different molecular masses, N-acetyl-β-D-glucosaminidases in two different forms. pH and temperature optima, thermal stability and kinetic properties of the two enzymes are strikingly similar in the polar E. superba versus the boreal euphausiid M. norvegica. Enzyme activity in the lower temperature range is still high, whereas activation energies are low in both euphausiids. This suggests a functional adaptation to a low temperature range in seawater.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00442038
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Moult cycle and seasonal activities of chitinolytic enzymes in the integument and digestive tract of the Antarctic krill, Euphausia superba (1989)
    Springer
    Polar biology 9 (1989), S. 311-317 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chitinolytic activity was quantified in euphausiid integuments in relation to moulting. In Euphausia superba, shortly before moult the activity increased in chitinase and N-acetyl-β-D-glucosaminidase to pronounced maxima indicating the onset of massive resorption of cuticular material. Enzymatic activity of E. superba corresponded to values in Meganyctiphanes norvegica, a boreal euphausiid which was investigated for comparison, as well as in insecta. Antarctic krill from winter catches displayed activities comparable to summer material suggesting physiological preparation for moulting. Accordingly, moulting did not cease during winter. Both enzymes were also active in the digestive tract in summer as well as in winter krill: chitin containing food of phyto-and zooplankton origin is digestable. Seasonally stable activities did not point to changes in nutritional preference. In contrast to other crustacea, digestive enzyme activity was not reduced around moult, suggesting a high capacity to continuously utilize food sources including chitin. This property can be linked directly to the high energy need caused by the necessity of constant active swimming in both krill species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00287429
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A laboratory study on digestive processes in the Antarctic krill, Euphausia superba, with special regard to chitinolytic enzymes (1999)
    Springer
    Polar biology 21 (1999), S. 295-304 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding experiments of 9, 14 and 20 days duration were carried out on the Antarctic krill, Euphausia superba. Two groups were fed with the chitinous diatom Cyclotella cryptica and the non-chitinous green algae Dunaliella bioculata, respectively. A control group remained unfed. The time courses of the activities of endo- and exochitinase in the stomach and the midgut gland were compared with those of the digestive enzymes protease, cellulase (1,4-β-d-glucanase) and laminarinase (1,3-β-d-glucanase). Specific activities of all enzymes were higher in the stomach than in the midgut gland. Characteristic time courses of activity were evident after 4 days. In starved animals, enzyme activities decreased to a minimum after 4 days and recovered within 14 days to initial values. In the stomach, the activities of endo- and exochitinase increased when krill were fed on Cyclotella. For animals fed with Dunaliella, activities stayed constant or decreased slightly. The results confirm chitinases as digestive enzymes and, therefore, the capability of krill to utilize various food sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050365
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  • 5
    Electronic Resource
    Electronic Resource
    The physiological response of Northern krill (Meganyctiphanes norvegica) to temperature gradients in the Kattegat (2000)
    Springer
    Hydrobiologia 426 (2000), S. 157-160 
    Details
    ISSN: 1573-5117
    Keywords: Meganyctiphanes norvegica ; respiration ; temperature ; vertical migration ; Kattegat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Alkor-Deep (140 m), which forms part of a depression system in the northern Kattegat channel east of the island of Læsø (Denmark), is the location of a self sustaining population of Northern krill, Meganyctiphanes norvegica (Euphausiacea). This population is exposed to one of the most pronounced thermal gradients within the distributional range of this pelagic crustacean. During summer, the temperature of the water column ranges between 4 and 6 in the deep to 16 °C near the surface which results in the krill being exposed to temperature differences of 8–10 °C during diel vertical migration. Oxygen consumption rates were used to investigate the physiological adaptation of the animal to such gradients in temperature. The rates were found to increase exponentially from 31 μmol O2 h-1 gdw -1 at 4 °C to 72 μmol O2 h-1 gdw -1 at 16 °C, giving a Q 10-value of 2.0, and indicating that physiological adaptation to varying thermal conditions does not take place. Behavioural adaptations are discussed which may help the krill to cope with large temperature gradients in their environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003974613473
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  • 6
    Electronic Resource
    Electronic Resource
    Brain death: practicability of evoked potentials (1992)
    Springer
    Neurosurgical review 15 (1992), S. 249-254 
    Details
    ISSN: 1437-2320
    Keywords: Brain death ; evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Multimodally evoked potentials were registered in 85 patients who fulfilled the criteria for brain death. While samatosensory and visual evoked potentials have been found to be of limited value for the diagnosis of brain death, the stepwise abolition of brain stem auditory evoked potentials (BAEP) confirmed brain death in 26 out of 85 patients, i. e. 31%. Registration of the abolition of BAEP is concluded to be a safe and acceptable confirmatory test. It is, however, more feasible for institutions, in which BAEP are analysed routinely. In spite of all efforts sequential BAEP could not be used for the diagnosis of brain death in the majority of cases either because of absence of reproducible responses at the initial registration or because the patient was already apnoic at the time of the initial BAEP. Assuming that bilateral preservation of wave I has the same significance as the stepwise abolition of BAEP, since it also proves the integrity of the peripheral receptor, BAEP are relevant for the declaration of brain death in approximately 30% of patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00257800
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  • 7
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    Euphausiid respiration model revamped. Latitudinal and seasonal shaping effects on krill respiration rates (2014)
    ELSEVIER SCIENCE BV
    In:  EPIC3Ecological Modelling, ELSEVIER SCIENCE BV, 291, pp. 233-241, ISSN: 0304-3800
    Details
    Publication Date: 2018-02-05
    Description: Euphausiids constitute a major biomass component in shelf ecosystems and play a fundamental role in the rapid vertical transport of carbon from the ocean surface to the deeper layers during their daily vertical migration (DVM). DVM depth and migration patterns depend on oceanographic conditions with respect to temperature, light and oxygen availability at depth, factors that are highly dependent on season in most marine regions. Here we introduce a global krill respiration ANN (artificial neural network) model including the effect of latitude (LAT), the day of the year (DoY), and the number of daylight hours (DLh), in addition to the basal variables that determine ectothermal oxygen consumption (temperature, body mass and depth). The newly implemented parameters link space and time in terms of season and photoperiod to krill respiration. The ANN model showed a better fit (r2 = 0.780) when DLh and LAT were included, indicating a decrease in respiration with increasing LAT and decreasing DLh. We therefore propose DLh as a potential variable to consider when building physiological models for both hemispheres. For single Euphausiid species investigated in a large range of DLh and DoY, we also tested the standard respiration rate for seasonality with Multiple Linear Regression (MLR) and General Additive model (GAM). GAM successfully integrated DLh (r2 = 0.563) and DoY (r2 = 0.572) effects on respiration rates of the Antarctic krill, Euphausia superba, yielding the minimum metabolic activity in mid-June and the maximum at the end of December. We could not detect DLh or DoY effects in the North Pacific krill Euphausia pacifica, and our findings for the North Atlantic krill Meganyctiphanes norvegica remained inconclusive because of insufficient seasonal data coverage. We strongly encourage comparative respiration measurements of worldwide Euphausiid key species at different seasons to improve accuracy in ecosystem modeling.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
    Format: application/pdf
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  • 8
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    Euphausiid respiration model revamped: latitudinal and seasonal shaping effects on krill respiration rates (2014)
    ELSEVIER SCIENCE BV
    In:  EPIC3Ecological Modelling, ELSEVIER SCIENCE BV, 291, pp. 233-241, ISSN: 0304-3800
    Details
    Publication Date: 2019-07-16
    Description: Euphausiids constitute a major biomass component in shelf ecosystems and play a fundamental role in the rapid vertical transport of carbon from the ocean surface to the deeper layers during their daily vertical migration (DVM). DVM depth and migration patterns depend on oceanographic conditions with respect to temperature, light and oxygen availability at depth, factors that are highly dependent on season in most marine regions. Here we introduce a global krill respiration ANN (Artificial Neural Network) model including the effect of latitude (LAT), the day of the year (DoY), and the number of daylight hours (DLh), in addition to the basal variables that determine ectothermal oxygen consumption (temperature, body mass and depth). The newly implemented parameters link space and time in terms of season and photoperiod to krill respiration. The ANN model showed a better fit (r2=0.780) when DLh and LAT were included, indicating a decrease in respiration with increasing LAT and decreasing DLh. We therefore propose DLh as a potential variable to consider when building physiological models for both hemispheres. For single Euphausiid species investigated in a large range of DLh and DoY, we also tested the standard respiration rate for seasonality with Multiple Linear Regression (MLR) and General Additive model (GAM). GAM successfully integrated DLh (r2= 0.563) and DoY (r2= 0.572) effects on respiration rates of the Antarctic krill, Euphausia superba, yielding the minimum metabolic activity in mid-June and the maximum at the end of December. We could not detect DLh or DoY effects in the North Pacific krill Euphausia pacifica, and our findings for the North Atlantic krill Meganyctiphanes norvegica remained inconclusive because of insufficient seasonal data coverage. We strongly encourage comparative respiration measurements of worldwide Euphausiid key species at different seasons to improve accuracy in ecosystem modelling.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 9
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    Balance of production and respiration in German Bight planktonic communities (1997)
    In:  EPIC3KUSTOS - TRANSWATT Meeting, Hamburg, 1997
    Details
    Publication Date: 2017-02-13
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 10
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    Physical controls on the dynamics of phytoplankton biomass, carbon flux and trophic interactions in the NorthAtlantic during the transition from regimes of winter convection to spring stratification - Cruise No.M87/1 – March 19 – May 02, 2012 – Lisbon (Portugal) – Reykjavik (Iceland). (2014)
    DFG-Senatskommission für Ozeanographie
    In:  EPIC3METEOR-Berichte,M87/1, DFG-Senatskommission für Ozeanographie, M87/1, 56 p.
    Details
    Publication Date: 2016-12-15
    Repository Name: EPIC Alfred Wegener Institut
    Type: Miscellaneous , notRev
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