Effects of bioturbation in oxic and hypoxic conditions: a microcosm experiment with a North Sea sediment community

Sediment cores of 20 cm diameter contaning the natural benthic fauna were subjected to low oxygen conditions in a laboratory microcosm system. After several days of oxic conditions ('oxic stage') the oxygen content of the water was reduced to 25% saturation for 15 d ('hypoxic stage'), followed by a 'reoxygenation stage'. Effective solute transport rates were calculated using measurements with the conservative tracer ion bromide. Profiles of oxygen and ΣCO2 were measured and molecular diffusive as well as effective fluxes, account mg for effective solute exchange, were calculated. The overall response of the benthic community was to compensate for low oxygen content of the overlying water by increased pumping activity. On average, effective diffusion coefficients (Den} were 3 times higher in hypoxia than under oxic conditions. D eff reached 1.5 x 10^-4 cm2 s^-1, a value 30 times that of molecular diffusion. During hypoxia we observed low molecular diffusive O2 flux, higher effective O2 flux, as well as an increase in ΣCO2 within the sediment. We interpret this as a shift of transport away from diffusion within the bulk sediment interstices (oxic conditions) to the advective transport pathways along burrows during hypoxia. This facilitates fast transport of oxygen and bromide along burrows and contrasts with the slower transport of CO2 from the interstices governed by molecular diffusion. In this transient situation calulations based on gradients result in an unrealistic molar ratio of fluxes(CO2/O2)as high as 11

Specific wheat fractions influence hepatic fat metabolism in diet-induced obese mice

Low whole grain consumption is a risk factor for the development of non-communicable diseases such as type 2 diabetes. Dietary fiber and phytochemicals are bioactive grain compounds, which could be involved in mediating these beneficial effects. These compounds are not equally distributed in the wheat grain, but are enriched in the bran and aleurone fractions. As little is known on physiological effects of different wheat fractions, the aim of this study was to investigate this aspect in an obesity model. For twelve weeks, C57BL/6J mice were fed high-fat diets (HFD), supplemented with one of four wheat fractions: whole grain flour, refined white flour, bran, or aleurone. The different diets did not affect body weight, however bran and aleurone decreased liver triglyceride content, and increased hepatic n-3 polyunsaturated fatty acid (PUFA) concentrations. Furthermore, lipidomics analysis revealed increased PUFA concentration in the lipid classes of phosphatidylcholine (PC), PC-ether, and phosphatidylinositol in the plasma of mice fed whole grain, bran, and aleurone supplemented diets, compared to refined white flour. Furthermore, bran, aleurone, and whole grain supplemented diets increased microbial alpha-diversity, but only bran and aleurone increased the cecal concentrations of short-chain fatty acids. The effects on hepatic lipid metabolism might thus at least partially be mediated by microbiota-dependent mechanisms

Trial and Error

Als Edward III. im Jahre 1337 einen Krieg mit Frankreich begann, war er aus strategischen Gründen dazu gezwungen, eine Allianz mit dem Kaiser des Heiligen Römischen Reiches und mehreren deutschen Fürsten einzugehen. Deshalb war es nötig hohe Summen an Bestechungsgeld an diese Verbündeten zu bezahlen. Kampfhandlungen sowie Diplomatie an anderen Fronten kosteten ebenfalls sehr viel Geld. Um diese Summen aufzubringen, griff der englische König auf verschiedenste Finanzierungspläne zurück. Direkte Steuern waren die einfachste Methode, allerdings erforderten sie die Zustimmung des Parlaments. In dem untersuchten Zeitraum war Edward III deshalb sehr um ihr Wohlwollen bemüht und musste häufig politische Zugeständnisse an das Unterhaus machen. Er fand aber bald heraus, dass er diese Zugeständnisse später widerrufen konnte, ohne mit ernsten Konsequenzen rechnen zu müssen. Der etwas schwierigere Weg der Finanzierung waren Kredite. Diese konnte er nur bekommen, da England damals der wichtigste Wollexporteur Europas war und vor allem die Tuchindustrie Flanderns vollkommen abhängig von englischer Wolle war. Mehrere Arten der Manipulation des Wollhandels wurden versucht, wobei vor allem die englischen Wollhändler und allen voran William de la Pole eine wichtige Rolle spielten. Anfängliche Versuche scheiterten aber ab 1343 wurde ein Finanzierungssystem verwendet das funktionierte. Das Jahr 1340 sah einen Bankrott des englischen Königs, da dieser die Ressourcen Englands überschätzt und sich durch militärische Abenteuer in Frankreich finanziell übernommen hatte. Gleichzeitig standen Teile seines Königreiches durch die hohe Steuerbelastung kurz vor einer Revolte. Edward provozierte daraufhin eine konstitutionelle Krise, die er dazu nutzte, viele einflussreiche politische Posten mit ihm bedingungslos loyalen Untergebenen neu zu besetzen. Aus dieser Krise ging er, aufgrund eines hohen Maßes an Pragmatismus und Opportunismus, hervor ohne etwas von seine

Prostate lymphoscintigraphy and radio-guided surgery for sentinel lymph node identification in prostate cancer - Technique and results of the first 350 cases

Introduction: Having in mind the promising results of lymphoscintigraphy and intraoperative gamma probe application for the detection of sentinel lymph nodes (SLN) in malignant melanoma, breast and penis cancer, we tried to identify the SLN in prostate cancer by applying a comparable technique. Materials and Method. 350 patients with prostate cancer were examined after providing informed consent. The day before pelvic lymphadenectomy technetium-99m nanocolloid was transrectally injected into the prostate under ultrasound guidance. A single central application was done per prostate lobe in most cases. Activity attained 90400 MBq, and the total injected volume was about 2-3 ml. Hereafter, lymphoscintigraphy was carried out. Those lymph nodes having been identified as SLN by means of gamma probe detection and lymphoscintigraphy were removed intraoperatively. Later, most of the cases had different types of pelvic lymphadenectomy. SLN received serial sections and immunohistochemistry, non-SLN step sections. Results: 335 patients showed at least 1 SLN in lymphoscintigraphy. 24.7% had lymph node metastases. In 2 patients, metastases in non-SLN were found without at least one SLN being affected (false-negative patient). Conclusion:Our experience suggests that the SLN identification is not only feasible in breast cancer and malignant melanoma, but also in prostate cancer with a comparable technique. Copyright (C) 2003 S. Karger AG, Basel

Angular correlations of coincident electron-positron pairs produced in heavy-ion collisions with nuclear time delay

We calculate angular correlations between coincident electron-positron pairs emitted in heavy-ion collisions with nuclear time delay. Special attention is directed to a comparison of supercritical and subcritical systems, where angular correlations of pairs produced in collisions of bare U nuclei are found to alter their sign for nuclear delay times of the order of 2 × 10-21 s. This effect is shown to occur exclusively in supercritical systems, where spontaneous positron creation is active

Seebeck coefficients of half-metallic ferromagnets

In this report the Co2 based Heusler compounds are discussed as potential materials for spin voltage generation. The compounds were synthesized by arcmelting and consequent annealing. Band structure calculations were performed and revealed the compounds to be half-metallic ferromagnets. Magnetometry was performed on the samples and the Curie temperatures and the magnetic moments were determined. The Seebeck coefficients were measured from low to ambient temperatures for all compounds. For selected compounds high temperature measurements up to 900 K were performed.Comment: accepted contribution o the Special Issue "Spin Caloritronics" of Solid State Communication