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  • 1
    Publikationsdatum: 2024-02-07
    Beschreibung: The effect of anthropogenic climate change in the ocean is challenging to project because atmosphere-ocean general circulation models (AOGCMs) respond differently to forcing. This study focuses on changes in the Atlantic Meridional Overturning Circulation (AMOC), ocean heat content (Δ OHC), and the spatial pattern of ocean dynamic sea level (Δ ζ). We analyse experiments following the FAFMIP protocol, in which AOGCMs are forced at the ocean surface with standardised heat, freshwater and momentum flux perturbations, typical of those produced by doubling CO 2. Using two new heat-flux-forced experiments, we find that the AMOC weakening is mainly caused by and linearly related to the North Atlantic heat flux perturbation, and further weakened by a positive coupled heat flux feedback. The quantitative relationships are model-dependent, but few models show significant AMOC change due to freshwater or momentum forcing, or to heat flux forcing outside the North Atlantic. AMOC decline causes warming at the South Atlantic-Southern Ocean interface. It does not strongly affect the global-mean vertical distribution of Δ OHC, which is dominated by the Southern Ocean. AMOC decline strongly affects Δ ζ in the North Atlantic, with smaller effects in the Southern Ocean and North Pacific. The ensemble-mean Δ ζ and Δ OHC patterns are mostly attributable to the heat added by the flux perturbation, with smaller effects from ocean heat and salinity redistribution. The ensemble spread, on the other hand, is largely due to redistribution, with pronounced disagreement among the AOGCMs.
    Materialart: Article , PeerReviewed
    Format: text
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  • 2
    ISSN: 1432-1351
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The compound eye of the crabHemigrapsus sanguineus undergoes daily changes in morphology as determined by light and electron microscopy, both in the quantity of chromophore substances studied by HPLC and in visual sensitivity as shown by electrophysiological techniques. 1. At a temperature of 20 °C, the rhabdom occupation ratio (ROR) of an ommatidial retinula was 11.6% (maximum) at midnight, 8.0 times larger than the minimum value at midday (1.4%) (Figs. 2, 6). 2. Observations by freeze-fracture revealed that the densities of intra-membranous particles (9–11 nm in diameter) of rhabdomeric membrane were ca. 2000/μm2 and ca. 3000/μm2 for night and daytime compound eyes, respectively (Fig. 3). 3. Screening pigment granules migrated longitudinally and aggregated at night, but dispersed during the day. Reflecting pigment granules migrate transversally in the proximal half of the retinula layer i.e. cytoplasmic extensions containing reflecting pigment granules squeeze between neighbouring retinula cells causing optical isolation (Fig. 4). Thus the screening pigment granules within the retinula cells show longitudinal migration and radial movement so that the daytime rhabdoms are closely surrounded by the pigment granules (Fig. 2). 4. At 20 °C, the total amount of chromophore of the visual pigment (11-cis and all-trans-retinal) was 1.4 times larger at night than during the day i.e. 46.6 pmol/eye at midnight and 33.2 pmol/eye at midday (Fig. 9). Calculations of the total surface area of rhabdomeric membrane, total number of intra-membranous particles in rhabdomeric membrane and the total number of chromophore molecules in a compound eye, indicate that a considerable amount of chromophore-protein complex exists outside the rhabdom during the day. 5. The change in rhabdom size and quantity of chromophore were highly dependent on temperature. At 10 °C both rhabdom size and amount of chromophore stayed close to daytime levels throughout the 24 hours (Figs. 6, 9). 6. The intracellularly determined relative sensitivity of the dark adapted night eye to a point source of light was about twice as high as the darkadapted day eye (Fig. 10). Most of the increase in the sensitivity is attributed primarily to the effect of reflecting pigment migration around the basement membrane (Fig. 4) and, secondarily, to the changes in the amount and properties of the photoreceptive membrane. The results form the basis of a detailed discussion as to how an apposition eye can function possibly as a night-eye.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 165 (1989), S. 589-604 
    ISSN: 1432-1351
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The intracellular distribution of visual pigments in the retinular cells of compound eyes of a butterfly (Papilio), a moth (Actias), a water scorpion (Ranatra), a dragonfly (Pantala), a crayfish (Procambarus), and a crab (Hemigrapsus) were investigated. The experiments measured the total surface area of rhabdom membrane in single compound eyes by light and electron microscopy, the densities of intramembrane particles in rhabdoms of compound eyes by freeze-fracture methods, and the quantities of chromophore molecules in compound eyes by high pressure liquid chromatography. Four species (moth, water scorpion, dragonfly, and crayfish) contain more than 75% of total chromophore probably as visual pigments in their rhabdoms, but the butterfly and the crab contain only 28.6% and 39.2%, respectively. The remainder of the chromophore molecules (Papilio 71.4%,Actias 5.7%,Ranatra 18.9%,Pantala 23.2%,Procambarus 24.3%, andHemigrapsus 60.8%) are supposed to exist mostly in the cytoplasm of the retinular cells. The localizing sites of such extrarhabdomeric chromophores are discussed in relation to the cytoplasmic membrane systems such as endoplasmic reticulum and lysosomal elements. In view of the results of the present experiment, it seems clear that the butterfly,Papilio, possesses a very large extra-rhabdomeric pool of chromophore that is available for rapid regeneration of visual pigment.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 46 (1998), S. 49-59 
    ISSN: 1573-0530
    Schlagwort(e): nonlinear sigma models ; conserved currents.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract In this Letter, we treat nonlinear sigma models such as the C P1-model, Q P1-model, etc. in 1+2 dimensions. For submodels of such models, we definitely construct an infinite number of nontrivial conserved currents. Our result is a generalization of Alvarez, Ferreira and Guillen.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Letters in mathematical physics 47 (1999), S. 159-171 
    ISSN: 1573-0530
    Schlagwort(e): Born–Infeld action ; Schur polynomials.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract In this Letter we introduce the (n+2)-dimensional Born–Infeld action with a dual field strength $$\tilde H$$ . We compute the field equation by using Schur polynomials and give a soliton solution.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    ISSN: 1436-2813
    Schlagwort(e): in vitro chemosensitivity test ; antitumor effect ; gastrointestinal and lung cancers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The results of two types of in vitro chemosensitivity tests, namely, the human tumor clonogenic assay (HTCA) and the succinic dehydrogenase inhibition assay (SDIA), for solid tumors, including stomach, colorectal and lung cancers, were analyzed and their correlation with clinical effects evaluated. The anticancer agents employed were mitomycin C (MMC), 5-fluorouracil (5-FU), adriamycin (ADM) and cisplatin (DDP). The evaluability rates of the assays were 54.5% for HTCA and 89.0% for SDIA. Among the 29 cases with evaluable lesions subjected to HTCA, there were 4 true positives, 9 false positives, and 16 true negatives, whereas among the 32 cases subjected to SDIA, the corresponding numbers were 2, 6, and 24, respectively. There were no false negatives for either assay, the accuracy of prediction for HTCA being 69.0% and for SDIA, 81.3%. The true positives of both assays included one complete response (CR) and five partial responses (PR), although the eventual outcome was cancer death in all cases. Interestingly, in five out of the six true positive cases, the agent involved was either ADM or DDP, both the which are usually regarded as “second line” anticancer agents for gastrointestinal carcinomas.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    ISSN: 1573-6903
    Schlagwort(e): Kinase C substrate ; 17K Mr protein ; myelin basic protein ; cytoskeleton ; synapse
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Cytoskeletal preparation obtained from synaptosome fractions of rat cerebrum contained the activity of kinase C, which phosphorylated 17K Mr protein endogenous to the preparation. The kinase C activity associated with the synaptosome cytoskeletons is greater in the cerebellum and hippocampus than in the cerebrum. The enhancement rates of phosphorylation of the 17K Mr protein were 293%, 544%, and 526% in the Triton X-100-insoluble fractions of synaptosomes prepared from cerebral cortex, hippocampus, and cerebellum, respectively. The 17K Mr protein was distinct from myelin basic protein (MBP) for the following reasons: 1) The electrophoretic mobility of the protein was slightly smaller than that of major MBP of rat in the polyacrylamide gel of 10–20% linear gradient, and the protein was not contained in the purified rat myelin. 2) The isoelectric point of the protein was in neutral range, whereas that of MBP was in alkaline one. 3) The 17K Mr protein did not cross-react with anti-MBP antibody. The protein was shown to be a major substrate contained in the cytoskeletal preparation of synaptosome obtained from cerebrum except for contaminating MBP. Only serine residue of the 17K Mr protein was phosphorylated by the kinase C endogenous to the preparation. The results suggest strongly that the synaptic role of protein kinase C through phosphorylation of the 17K Mr protein.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Neurochemical research 11 (1986), S. 543-555 
    ISSN: 1573-6903
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effect of synaptic junction (SJ) on microtubule assembly was examined. After preincubation with ATP at 37°C, rat SJ decreased the initial velocity and the extent of the porcine brain microtubule assembly (initiated by the addition of GTP) in a Ca2+/calmodulin (CaM)-dependent manner. The degree of the inhibition reached 35% of the control assembly (0-min preincubation) after 20-min preincubation with ATP. There was no inhibition either with heat-treated SJ, at 0°C, or in the presence of EGTA or W-7 (CaM antagonist). The inhibition was due neither to protease(s) nor CaM contaminating the preparations. Free Ca2+ concentration level required for the inhibition of microtubule assembly was 10−6 M. Phosphorylation of microtubule proteins was inhibited by SJ in a Ca2+/CaM-dependent manner, and the inhibition occurred in a physiological increase range of intracellular Ca2+ concentration (10−6M) The heat-treated SJ caused no inhibition. The result suggested that the microtubule assembly in the postsynaptic region was regulated by a Ca2+/CaM-dependent protein kinase associated with SJ; i. e., major postsynaptic density protein.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    ISSN: 1741-0444
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Beschreibung / Inhaltsverzeichnis: Sommaire Au cours des dernières années le nombre de personnes tuées dans les accidents de circulation s’est considérablement accru au Japon: il est considéré que la moitié des victimes aurait pû être sauvée par des interventions effectuées d’urgence. En vue de ce fait, les auteurs ont construit un nouveau type d’encéphalographe à echo, avec transistor, portatif, comportant le bloc principal et un indicateur, pesant 6 Kg. chacun. L’appareil utilise une combinaison de méthodes de transmission et de réflection, la première servant à déterminer si les rayons de son, projetés à travers les régions temporales à partir de chaque côté de la tête, sont co-linéaires. La marge de sécurité de l’irradiation a été déterminée par les auteurs après des expériences faites sur des chiens, comportant une analyse quantitative de la transaminase glutamique oxalacétique et de la transaminase glutamique pyruvique dans le serum et le liquide encéphalorachidien de ces animaux. Aucun effect nocif n’a été constaté à condition que l’irradiation soit brève.
    Kurzfassung: Zusammenfassung Die Anzahl der Verkehrstoten in Japan ist in den letzten Jahren erheblich gestiegen: die Hälfte dieser Personen hätte gerettet werden können, wenn die Möglichkeit zur Durchführung von Behelfsoperationen bestanden hätte. Die Autoren haben deshalb einen neuen tragbaren Echo-Enzephalographen mit Transistoren entwickelt, der aus einem Hauptteil und einem Anzeigegerät besteht. Jedes Teil wiegt 6 kg. Der Apparat arbeitet mit einer Kombination von Transmissions-und Reflexionsmethoden, erstere um festzustellen, ob Schallstrahlen, die von jeder Kopfseite aus durch die Schläfenpartien projeziert werden, kolineär sind. Die Verfasser haben den Sicherheitsbereich für Bestrahlung experimentell an Hunden ermittelt, und zwar durch quantitative Analyse der Glutamin-Oxalessig-Transaminase und der Glutamin-Pyrotraubensäure-Transaminase im Serum und in der Cerebrospinalflüssigkeit. Es schienen keine schädlichen Wirkungen aufzutreten, vorausgesetzt die Bestrahlung bleibt kurz.
    Notizen: Abstract In recent years, the number of persons killed in traffic accidents has risen trementdously in Japan; it is considered that half of these could have been saved if emergency operations had been performed. In consequence, the authors have made a new type of portable, transistorized, echo-encephalograph, comprising a main part and an indicator; the weight of each is 6 Kg. The apparatus uses a combination of the transmission and reflection methods, the former to detect when sound beams, projected through the temporal regions from each side of the head, are colinear. The authors carried out an experiment to decide a safe range of irradiation, by quantitative analysis of the glutamic oxalacetic transaminase and the glutamic pyruvic transaminase in the serum and cerebrospinal fluid of dogs. There seemed to be no harmful effects, provided irradiation is brief.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of oceanography 56 (2000), S. 485-494 
    ISSN: 1573-868X
    Schlagwort(e): Intraseasonal variation ; ENSO ; zonal wind ; warm water pool ; equatorial Pacific ; GCM
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract The effects of intra-seasonal wind forcing on the mean field of the tropical Pacific Ocean has been studied using an ocean general circulation model (GCM). Idealized intra-seasonal zonal wind forcing with zero mean, which propagates eastward, induces net eastward jets at the equator that shift the warm water pool to the east. The mean temperature of the upper 200 m of the ocean increases off the equator and decreases at the equator. The change is independent of the propagation speed of the intra-seasonal wind forcing. The magnitude of the change depends on the amplitude and the period of the forcing, and the ocean structure, while the spatial pattern is independent of these parameters. A simple shallow water model is used to explain these changes. It is found that the term responsible for the enhanced eastward Equatorial jet is the Reynolds stress term, which arises from a phase shift of the zonal current due to friction. The resultant convergence of eastward momentum on the equator and geostrophic adjustment of the interface to the change of zonal current brings about the thermal redistribution of the upper ocean seen in the GCM.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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