Effects of experimental CO2 leakage on solubility and transport of seven trace metals in seawater and sediment

The impact of CO₂ leakage on solubility and distribution of trace metals in seawater and sediment has been studied in lab scale chambers. Seven metals (Al, Cr, Ni, Pb, Cd, Cu, and Zn) were investigated in membrane-filtered seawater samples, and DGT samplers were deployed in water and sediment during the experiment. During the first phase (16 days), “dissolved” (< 0.2 µm) concentrations of all elements increased substantially in the water. The increase in dissolved fractions of Al, Cr, Ni, Cu, Zn, Cd and Pb in the CO₂ seepage chamber was respectively 5.1, 3.8, 4.5, 3.2, 1.4, 2.3 and 1.3 times higher than the dissolved concentrations of these metals in the control. During the second phase of the experiment (10 days) with the same sediment but replenished seawater, the dissolved fractions of Al, Cr, Cd, and Zn were partly removed from the water column in the CO₂ chamber. DNi and DCu still increased but at reduced rates, while DPb increased faster than that was observed during the first phase. DGT-labile fractions (Me_DGT) of all metals increased substantially during the first phase of CO₂ seepage. DGT-labile fractions of Al, Cr, Ni, Cu, Zn, Cd and Pb were respectively 7.9, 2.0, 3.6, 1.7, 2.1, 1.9 and 2.3 times higher in the CO₂ chamber than that of in the control chamber. Al_DGT, Cr_DGT, Ni_DGT, and Pb_DGT continued to increase during the second phase of the experiment. There was no change in Cd_DGT during the second phase, while Cu_DGT and Zn_DGT decreased by 30% and 25%, respectively in the CO₂ chamber. In the sediment pore water, DGT labile fractions of all the seven elements increased substantially in the CO₂ chamber. Our results show that CO₂ leakage affected the solubility, particle reactivity and transformation rates of the studied metals in sediment and at the sediment-water interface. The metal species released due to CO₂ acidification may have sufficiently long residence time in the seawater to affect bioavailability and toxicity of the metals to biota.     

Fatigue model for elastic bars in turbulent wind

Accumulated fatigue damage of an elastic structural bar vibrating in natural turbulent wind may be a primary cause of structural failure. Clumps of strong lateral oscillations may occur randomly with time. These oscillations are due to resonance between the vortex shedding frequency and the natural frequency of the bar. The so-called “lock in” phenomenon apparently extends resonance from a point of coincidence to an interval. An idealized stochastic model is set up on the basis of the empirically observed existence of a critical interval of undisturbed wind velocities upwind of the bar. The upwind velocities are modeled as realizations of a specific stochastic process. A clump of strong lateral, damped harmonic oscillations occurs during any uninterrupted “visit” of the velocity to the critical interval. For velocities outside the critical interval only insignificant lateral oscillations occur. The fatigue damage is assumed to be linearly accumulated according to the Palmgren—Miner rule within each clump and from clump to clump. The goal is to evaluate the structural reliability for any specified period of time. It is expressed in terms of a reliability index.     

Repertoire Contraction

The basic assumption of repertoire contraction is that only some of the logically closed subsets of the original belief set are viable as contraction outcomes. Contraction takes the form of choosing directly among these viable outcomes, rather than among cognitively more far-fetched objects such as possible worlds or maximal consistent subsets of the original belief set. In this first investigation of repertoire contraction, postulates for various variants of the operation are introduced. Necessary and sufficient conditions are given for when repertoire contraction coincides with AGM contraction or with operations generated by AGM-style contraction on a belief base. A close connection is shown to hold between repertoire contraction and specified meet contraction.     

Two-level approach to efficient visualization of protein dynamics

Proteins are highly flexible and large amplitude deformations of their structure, also called slow dynamics, are often decisive to their function. We present a two-level rendering approach that enables visualization of slow dynamics of large protein assemblies. Our approach is aligned with a hierarchical model of large scale molecules. Instead of constantly updating positions of large amounts of atoms, we update the position and rotation of residues, i.e., higher level building blocks of a protein. Residues are represented by one vertex only indicating its position and additional information defining the rotation. The atoms in the residues are generated on-the-fly on the GPU, exploiting the new graphics hardware geometry shader capabilities. Moreover, we represent the atoms by billboards instead of tessellated spheres. Our representation is then significantly faster and pixel precise. We demonstrate the usefulness of our new approach in the context of our collaborative bioinformatics project.     

Properties of Calanus finmarchicus biomass during frozen storage after heat inactivation of autolytic enzymes

Calanus finmarchicus is a marine zooplankton of interest for the aquaculture industry, as well as for nutraceuticals and the cosmetic industry. The chemical composition of C. finmarchicus rapidly changes postmortem due to autolytic processes; in particular phospholipids rapidly degrade to give free fatty acids. The aim of this study was to inactivate autolytic enzymes in C. finmarchicus by applying heat (72 °C, 5-30 min) through mixing with boiling, fresh water, and further to explore the effects of heat (70 °C, 15 min) combined with long time storage (−20 °C, 12 months) of treated and untreated material. Heat treatment (5 min) inactivated all tested enzymes and maintained the initial amount of phospholipids, total lipids and crude protein. Storage of untreated material led to complete degradation of all phospholipids, whereas heat treatment resulted in a stable product containing the initial amount of phospholipids and astaxanthin.     

Phonemic fluency deficits in asymptomatic gene carriers for Huntington's disease.

The aim of the present study was to investigate verbal fluency in preclinical Huntington's disease (HD). Phonemic and semantic fluency and the rate of word production over time were assessed for 29 asymptomatic gene carriers and 34 noncarriers of HD. The relationship between fluency tasks and other cognitive domains was investigated. Compared to noncarriers, carriers produced fewer words and produced them more slowly in the phonemic fluency task but not in the semantic fluency task. When the carrier group was divided on the basis of Predicted-Years-To-Onset (PYTO), only carriers with     

Video-based Vibration Analysis by Modulated Projected Gratings

Abstract

We describe a time-averaging method for vibration analysis using white-light moiré technique and video recording. Phase modulation is used to obtain information on both the vibration amplitude and the vibration phase. The vibration fringe function is discussed for projection gratings. A method which makes it possible to reveal the amplitude and phase distribution by use of a digital image-processing system and phase-stepping technique is described. The results of implementing the method are shown.