Studies on silica-scaled chrysophytes from Fujian Province, China

rmDUCTIONEXtensiveinvestigaionsonthemphicaldistributionofsilica-scaledchrysoPhytesinChinahaVebeeninprogresssincel988.Kristiansen(l989,199o),Kristiansen&TOng(l988,l989a,l989bandl99l)andWei&Kristiansen(1994)rePOrtedtheirre-sultsofstUdiesonsilica-scaledchrysoPhyteshantheeastem,northeasern,western,southwsternandcentndPaItsofChina(includingllprovinces).kltogether6ltaxawererecoIded,mostofthembelongingtothegenusMallomonas.Al993tol994simultaneousstirveyofthephytoplankonandstUdyofthesilica-sc…     

State-space representation of radiation forces in time-domain vessel models

The paper presents a method for generating a new and efficient time-domain formulation of the equations of motion for a vessel with frequency-dependent hydrodynamic coefficients. Previous work on this topic has relied on the use of convolution terms, whereas in this work state-space models are used. This leads to a model formulation that is well suited for controller design and simulation.     

A Younger Dryas Ash Bed in western Norway,and its possible correlations with tephra in cores from the Norwegian Sea and the North Atlantic

A bed of volcanic ash up to 23 cm thick is found in lacustrine and marine sediments in western Norway. It is formally mamed the Vedde Ash Bed, and its age is approximately 10,600 yr B.P., i.e., mid-Younger Dryas. The bed consits of pure glass having a bimodal basaltic and rhyolitic somposition. The geochemistry of the glass shards suggests an Icelandic source. By means of stratigraphic position and geochemistry, the ash is correlated with ash zones found in cores from the continental shelf, the Norwegian Sea, and the North Atlatic.     

Physiological effects of hypercapnia in the deep-sea bivalve Acesta excavata (Fabricius, 1779) (Bivalvia; Limidae)

The option of storing CO₂ in subsea rock formations to mitigate future increases in atmospheric CO₂ may induce problems for animals in the deep sea. In the present study the deep-sea bivalve Acesta excavata was subjected to environmental hypercapnia (pHSW 6.35, PCO₂ = 33,000 μatm) corresponding to conditions reported from natural CO₂ seeps. Effects on acid–base status and metabolic rate were related to time of exposure and subsequent recovery. During exposure there was an uncompensated drop in both hemolymph and intracellular pH. Intracellular pH returned to control values, while extracellular pH remained significantly lower during recovery. Intracellular non-bicarbonate buffering capacity of the posterior adductor muscle of hypercapnic animals was significantly lower than control values, but this was not the case for the remaining tissues analyzed. Oxygen consumption initially dropped by 60%, but then increased during the final stages of exposure, which may suggest a higher tolerance to hypercapnia than expected for a deep-living species.