Distribution and lipid composition of early life stages of the cranchiid squid Galiteuthis glacialis (Chun) in the Weddell Sea, Antarctica

The relatively small numbers of pelagic cephalopods caught in the RMT-8 samples (0–300 m) in February/March 1983 in the Weddell Sea were dominated by early life stages of the cranchiid squid Galiteuthis glacialis. A total of 48 specimens were caught with dorsal mantle length (ML) ranging from 4–36 mm. They occurred with a mean density of 0.15 ind. × 1000 m−3 and were present in 38% of 33 RMT-8 samples. G. glacialis was the only cranchiid squid found in the Weddell Sea between 66° and 74°S. Its early life stages were concentrated in the layers below the summer thermocline (>50 m) and body sizes appeared to increase towards deeper water layers. For biochemical analyses, nine specimens of G. glacialis (ML 6–18 mm) were sampled in the eastern Weddell Sea between 185–520 m water depth in January/February 1985. Total lipid contents ranged from 8%–11% dry weight (DW) with phospholipids being the main lipid component (43–56% of total lipid). Storage lipids (triacylglycerols) made up 18–26% of total lipid. The relatively low lipid contents may reflect the early development stage of the specimens examined. The data presented give the first information on geographical and vertical distribution patterns of early life stages of G. glacialis in the high-Antarctic Weddell Sea, as well as on their lipid content and composition

Seasonal lipid dynamics of the copepods Pseudocalanus minutus (Calanoida) and Oithona similis (Cyclopoida) in the Arctic Kongsfjorden (Svalbard)

Seasonal lipid dynamics of various developmental stages were investigated in Pseudocalanus minutus and Oithona similis. For P. minutus, the dominance of 16:1(n−7), 16:4(n−3) and 20:5(n−3) fatty acids indicated a diatom-based nutrition in spring, whereas 22:6(n−3), 16:0, 18:2(n−6) and 18:1(n−9) pointed to a flagellate-based diet during the rest of the year as well as omnivorous/carnivorous low-level feeding during winter. The shorter-chain fatty alcohols 14:0 and 16:0 prevailed, also reflecting biosynthetic processes typical of omnivores or carnivores. Altogether, the lipid signatures characterized P. minutus as an opportunistic feeder. In contrast, O. similis had consistently high amounts of the 18:1(n−9) fatty acid in all stages and during all seasons pointing to a generally omnivorous/carnivorous/detritivorous diet. Furthermore, the fatty alcohol 20:1(n−9) reached high percentages especially in adult females and males, and feeding on Calanus faecal pellets is suggested. Fatty alcohols, as wax ester moieties, revealed significant seasonal variations in O. similis and a seasonal trend towards wax ester accumulation in autumn in P. minutus. P. minutus utilized its lipid deposits for development in the copepodite stages III and IV and for gonad maturation in CV and females during the dark season. However, CVs and females depended on the spring phytoplankton bloom for final maturation processes and reproduction. O. similis fueled gonad maturation and egg production for reproduction in June by wax esters, whereas reproduction in August/September co-occurred with the accumulation of new depot lipids. Both species revealed significantly higher wax ester levels in deeper (>50 m) as compared to surface (0–50 m) dwelling individuals related to a descent prior to overwintering

A new model for quantum dot light emitting-absorbing devices

Motivated by the Jaynes-Cummings (JC) model, we consider here a quantum dot coupled simultaneously to a reservoir of photons and to two electric leads (free-fermion reservoirs). This Jaynes-Cummings-Leads (JCL) model makes possible that the fermion current through the dot creates a photon flux, which describes a light-emitting device. The same model is also describe a transformation of the photon flux into current of fermions, i.e. a quantum dot light-absorbing device. The key tool to obtain these results is an abstract Landauer-Büttiker formula

XML-Verarbeitung auf Grafikkarten

Die Extensible Markup Language (XML) ist ein weit verbreitetes, strukturiertes Format zur Datenspeicherung und zum Datenaustausch. Die Komplexität und die Menge der zu verarbeitenden XML-Daten hat in den vergangenen Jahren erheblich zugenommen, und sowohl in der Wissenschaft wie auch in der Wirtschaft wird an Verfahren zur schnellen Verarbeitung von XML gearbeitet. In einigen Arbeiten werden auch Verfahren zur parallelen Verarbeitung von XML mittels üblicher Mehrkern-CPUs entwickelt. Seit einigen Jahren gewinnt die parallele Verarbeitung allgemeiner Probleme mittels Grafikprozessoren (GPUs) an Bedeutung. GPUs ähneln in ihrer Architektur und Arbeitsweise dem bekannten Single Instruction Multiple Data-Prinzip. Daher sind GPUs besonders gut geeignet für die Verarbeitung massiv-datenparalleler Probleme wie etwa der Matrixmultiplikation oder der Bildverarbeitung. XML-Dokumente bzw. XML-Datenmodelle haben eine baumartige Struktur und folglich basieren viele der Verfahren zur Verarbeitung von XML auf dieser Baumstruktur. Solche Strukturen und Verfahren können jedoch wegen der Architektur von GPUs nicht trivial von CPUs auf GPUs übertragen werden, selbst wenn es sich um Verfahren zur parallelen Verarbeitung mittels Mehrkern-CPUs handelt. Daher existieren bisher kaum Arbeiten, die die parallele Verarbeitung von XML mittels GPUs untersuchen. In der vorliegenden Arbeit wird anhand einer konkreten XML-Anwendung, der Transformation von XML-Dokumenten mit XSLT, untersucht, inwieweit die Verarbeitung von XML an die massiv-parallele Architektur von GPUs angepasst werden kann. Dazu wird zunächst ein Konzept zur XSLT-Verarbeitung durch GPUs entworfen und danach werden die vier wichtigsten in diesem Konzept eingesetzten neuen Verfahren vorgestellt: ein schnelles Sortierverfahren für GPUs, ein Verfahren um GPUs als asynchrone Koprozessoren für die CPU einsetzen zu können, ein Verfahren um XPath-Ausdrücke parallel auszuwerten und schließlich ein Verfahren zur XSLT-Verarbeitung mittels GPUs. In umfangreichen Tests wird gezeigt, dass mit den hier dargelegten Verfahren die Nutzung von GPUs für die XPath- und XSLT-Verarbeitung in vielen Fällen zu einer Leistungssteigerung gegenüber der Verarbeitung durch Mehrkern-CPUs führt. Es ist demnach möglich, GPUs auch zur Verarbeitung von XML gewinnbringend einzusetzen

Molecular aspects of lipid metabolism in the midgut gland of the brown shrimp Crangon crangon

The brown shrimp, Crangon crangon, is well adapted to the variable environmental conditions in the southern North Sea. It is very abundant, has high reproduction rates, and holds a key position in coastal ecosystems. This species has very low lipid deposits in the midgut gland, suggesting that the main function of the midgut gland is metabolic turnover rather than energy storage. Based on seasonal gene expression studies and established transcriptome data, we investigated key components of lipid metabolic pathways. Gene expression of triacylglycerol lipase, phospholipase, and fatty acid desaturase were analyzed and compared with that of other digestive enzymes involved in lipid, carbohydrate, and protein catabolism. Our results suggest that gene expression of digestive enzymes involved in lipid metabolism is modulated by the lipid content in the midgut gland and is related to food availability. Brown shrimp seem to be capable of using cellular phospholipids during periods of food paucity but high energetic (lipid) requirements. Two of three isoforms of fatty acid binding proteins (FABPs) from the midgut gland involved in fatty acid transport showed specific mutations of the binding site. We hypothesize that the mutations in FABPs and deficiencies in anabolic pathways limit lipid storage capacities in the midgut gland of C. crangon. In turn, food utilization, including lipid catabolism, has to be efficient to fulfill the energetic requirements of brown shrimp

A new model for quantum dot light emitting-absorbing devices : dedicated to the memory of Pierre Duclos

Motivated by the Jaynes-Cummings (JC) model, we consider here a quantum dot coupled simultaneously to a reservoir of photons and to two electric leads (free-fermion reservoirs). This Jaynes-Cummings-Leads (JCL) model makes possible that the fermion current through the dot creates a photon flux, which describes a light-emitting device. The same model also describes a transformation of the photon flux into a fermion current, i.e. a quantum dot light-absorbing device. The key tool to obtain these results is an abstract Landauer-Büttiker formula

The Role of Zooplankton Grazing and Nutrient Recycling for Global Ocean Biogeochemistry and Phytoplankton Phenology

Zooplankton plays a notable role in ocean biogeochemical cycles. However, it is often simulated as one generic group and top closure term in ocean biogeochemical models. This study presents the description of three zooplankton functional types (zPFTs, micro-, meso- and macrozooplankton) in the ocean biogeochemical model FESOM-REcoM. In the presented model, microzooplankton is a fast-growing herbivore group, mesozooplankton is another major consumer of phytoplankton, and macrozooplankton is a slow-growing group with a low temperature optimum. Meso- and macrozooplankton produce fast-sinking fecal pellets. With three zPFTs, the annual mean zooplankton biomass increases threefold to 210 Tg C. The new food web structure leads to a 25% increase in net primary production and a 10% decrease in export production globally. Consequently, the export ratio decreases from 17% to 12% in the model. The description of three zPFTs reduces model mismatches with observed dissolved inorganic nitrogen and chlorophyll concentrations in the South Pacific and the Arctic Ocean, respectively. Representation of three zPFTs also strongly affects phytoplankton phenology: Fast nutrient recycling by zooplankton sustains higher chlorophyll concentrations in summer and autumn. Additional zooplankton grazing delays the start of the phytoplankton bloom by 3 weeks and controls the magnitude of the bloom peak in the Southern Ocean. As a result, the system switches from a light-controlled Sverdrup system to a dilution-controlled Behrenfeld system. Overall, the results suggest that representation of multiple zPFTs is important to capture underlying processes that may shape the response of ecosystems and ecosystem services to on-going and future environmental change in model projections