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Previous studies indicate that the hatching success of brine shrimp ( Artemia franciscana) cysts is surprisingly sensitive to ambient metal concentrations. These studies estimated median effective concentrations (EC50s) of 7, 5, and 28 μg l−1 for Cd, Cu, and Zn, suggesting that the hatching end point for A. franciscana is the most sensitive tested to date for Cd and Zn in saline environments and comparable in sensitivity with the most sensitive tested to date for Cu. Furthermore, these data suggest that brine shrimp are at significant risk from Cu and Zn in Great Salt Lake (GSL), UT, where ambient concentrations as high as 10 and 14 μg l−1, respectively, have been measured. Given that brine shrimp appear to be successfully reproducing in GSL, we hypothesized that these toxicity values were either biased low as a result of an artifact of the test method used or that site-specific water-quality conditions in the lake had decreased metal bioavailability such that brine shrimp could successfully reproduce. To test these hypotheses, we initiated a step-wise series of experiments. First we investigated the effects of pretreatment of brine shrimp cysts with antibiotics on brine shrimp sensitivity to metals because previous investigators as part of their test methods have used antibiotics. Next we considered the effect of ionic composition of the artificial test media on sensitivity. Finally, we evaluated the effects of the site-specific water quality of the GSL on metal bioavailability and toxicity. Results indicate that pretreatment of cysts with antibiotics had no effect on sensitivity. However, we were unable to repeat the previous values for Cd and Zn, obtaining EC50s of 11,859 and 289 μg l−1 for Cd and Zn, respectively. For Cu, however, we estimated an EC50 of 12 μg l−1, so we conducted further testing on the artificial media, adjusting the media composition to better reflect the Ca2+ and HCO concentration of normal seawater. This increased the EC50 to 28 μg l−1. Finally we evaluated the toxicity of Cu in GSL water and obtained an EC50 of 68 μg l−1, suggesting that the increased dissolved organic carbon in GSL has a significant protective effect. Overall, the results of this study suggest that brine shrimp hatching success is not particularly sensitive to Cd and Zn, but it is sensitive to Cu. However, site-specific water-quality conditions ensure that brine shrimp cyst hatching success is not significantly affected by any of these metals at the normal background concentrations that occur in GSL (<15 μg l−1). [ABSTRACT FROM AUTHOR]

The nature of the reduction trend and quasi-decadal oscillation in Northern Hemisphere sea-ice extent is investigated. The trend and oscillation that seem to be two separate phenomena have been found in data. This study examines a hypothesis that the Arctic sea-ice reduction trend in the last three decades amplified the quasi-decadal Arctic sea-ice oscillation (ASIO) due to a positive ice/ocean-albedo feedback, based on data analysis and a conceptual model proposed by Ikeda et al. The theoretical, conceptual model predicts that the quasi-decadal oscillation is amplified by the thinning sea-ice, leading to the ASIO, which is driven by the strong positive feedback between the atmosphere and ice-ocean systems. Such oscillation is predicted to be out-of-phase between the Arctic Basin and the Nordic Seas with a phase difference of 3p/4, with the Nordic Seas leading the Arctic. The wavelet analysis of the sea ice data reveals that the quasi-decadal ASIO occurred actively since the 1970s following the trend starting in the 1960s (i.e., as sea-ice became thinner and thinner), as the atmosphere experienced quasi-decadal oscillations during the last century. The wavelet analysis also confirms the prediction of such out-of-phase feature between these two basins, which varied from 0.62p in 1960 to 0.25p in 1995. Furthermore, a coupled ice-ocean general circulation model (GCM) was used to simulate two scenarios, one without the greenhouse gas warming and the other having realistic atmospheric forcing along with the warming that leads to sea-ice reduction trend. The quasi-decadal ASIO is excited in the latter case compared to the no-warming case. The wavelet analyses of the simulated ice volume were also conducted to derive decadal ASIO and similar phase relationship between the Arctic Ocean and the Nordic Seas. An independent data source was used to confirm such decadal oscillation in the upper layer (or freshwater) thickness, which is consistent with the model simulation. A modified feedback loop for the sea-ice trend and ASIO was proposed based on the previous one by Mysak and Venegas and the ice/albedo and cloud/albedo feedabcks, which are responsible for the sea ice reduction trend. [ABSTRACT FROM AUTHOR]

Cellulose oligomer's obtained by a new degradation method (pivaloylysis) are used as starting materials in organic synthesis. On the one hand these oligomer's are functionalized to potent glycolyl donors, on the other hand several methods are shown to generate different types of hydroxy compounds (glycolyl acceptors). Glycosidation reactions performed with these two types of building blocks allow an access to linear products (unidisperse celluloses) as well as to new branched cellulose units. [ABSTRACT FROM AUTHOR]

Freshening of high latitude surface waters can change the large-scale oceanic transport of heat and salt. Consequently, atmospheric and sea ice perturbations over the deep water production sites excite a large-scale response establishing an oceanic "teleconnection" with time scales of years to centuries. To study these feedbacks, a coupled atmosphere-ocean-sea ice model consisting of a two dimensional atmospheric energy and moisture balance model (EMBM) coupled to a thermodynamic sea ice model and an ocean general circulation model is utilised. The coupled model reproduces many aspects of the present oceanic circulation. We also investigate the climate impact of changes in fresh water balance during an ice age initiation. In this experiment part of the precipitation over continents is stored within continental ice sheets. During the buildup of ice sheets the oceanic stratification in the North Atlantic is weakened by a reduced continental run-off leading to an enhanced thermohaline circulation. Under these conditions salinity is redistributed such that deep water is more saline than under present conditions. Once the ice sheets built up, we simulate an ice age climate without net fresh water storage on the continents. In this case the coupled model reproduces the shallow and weak overturning cell, an ice edge advance insulating the upper ocean, and many other aspects of the glacial circulation. [ABSTRACT FROM AUTHOR]

We investigate the dependence of surface fresh water fluxes in the Gulf Stream and North Atlantic Current (NAC) area on the position of the stream axis which is not well represented in most ocean models. To correct this shortcoming, strong unrealistic surface fresh water fluxes have to be applied that lead to an incorrect salt balance of the current system. The unrealistic surface fluxes required by the oceanic component may force flux adjustments and may cause fictitious long-term variability in coupled climate models. To identify the important points in the correct representation of the salt balance of the Gulf Stream a regional model of the northwestern part of the subtropical gyre has been set up. Sensitivity studies are made where the westward flow north of the Gulf Stream and its properties are varied. Increasing westward volume transport leads to a southward migration of the Gulf Stream separation point along the American coast. The salinity of the inflow is essential for realistic surface fresh water fluxes and the water mass distribution. The subpolar–subtropical connection is important in two ways: The deep dense flow from the deep water mass formation areas sets up the cyclonic circulation cell north of the Gulf Stream. The surface and mid depth flow of fresh water collected at high northern latitudes is mixed into the Gulf Stream and compensates for the net evaporation at the surface. [ABSTRACT FROM AUTHOR]

This paper presents a vision system that provides a robust identification and localization of 2-D objects in industrial scenes. A symbolic image description based on the polygonal approximation of the object silhouette is extracted in video real time by the use of dedicated hardware. A two-stage matching algorithm is proposed. At the first stage hypotheses for assignments of image to model polygons are generated together with hypotheses for the object's pose. Corresponding continuous measures of similarity are derived from the turning functions of the curves. At the second stage compatible matches of polygons are collected by using a voting scheme in transformation space. Experimental results reveal the fault tolerance of the vision system with regard to noisy and broken image contours, as well as partial occlusion of objects. The robustness and easy adaptability of the vision system make it well suited for a wide variety of applications. [ABSTRACT FROM AUTHOR]

Processes on the microscale determine the macroscopic behaviour of metallic materials and should therefore be considered during the development of constitutive macroscopic equations used for engineering calculations. The article reviews the mathematical formulation of the most significant of these processes, such as dislocation motion due to thermal and mechanical activation and the development of internal structures during plastic deformation. It describes the consideration of these relations in a stochastic model for the inelastic behaviour of metals and shows the comparison between predictions of this model and experimental findings. [ABSTRACT FROM AUTHOR]