Rezente submarine Barytbildung im Derugin Becken (Ochotskisches Meer): geochemische Prozesse an aktiven Fluidaustrittsstellen

In dieser Arbeit werden Untersuchungen an Cold Vent-beeinflussten Sedimenten, Porenwässern und Mineralpräzipitaten des Derugin Beckens vorgestellt, einer 1500–1800 m tiefen Depression im Ochotskischen Meer. Die Fluidaustrittsstellen befinden sich in etwa 1500 m Wassertiefe, entlang einer E-W verlaufenden morphologischen Erhebung, und sind charakterisiert durch beeindruckende, groß-flächige Barytablagerungen (BaSO4) in Assoziation mit chemoautothrophen Lebensgemeinschaften (z. B. Calyptogena sp. und Acharax sp.), die auf eine rezente Aktivität der Quellen hinweisen

Heuristic-based information acquisition and decision-making among pilots

Objective: This research was designed to examine the impact of heuristic-based approaches to the acquisition of task-related information on the selection of an optimal alternative during simulated in-flight decision making. Background: The work integrated features of naturalistic and normative decision making and strategies of information acquisition within a computer-based, decision support framework. Method: The study comprised two phases, the first of which involved familiarizing pilots with three different heuristic-based strategies of information acquisition: frequency, elimination by aspects, and majority of confirming decisions. The second stage enabled participants to choose one of the three strategies of information acquisition to resolve a fourth (choice) scenario. Results: The results indicated that task-oriented experience, rather than the information acquisition strategies, predicted the selection of the optimal alternative. It was also evident that of the three strategies available, the elimination by aspects information acquisition strategy was preferred by most participants. Conclusion: It was concluded that task-oriented experience, rather than the process of information acquisition, predicted task accuracy during the decision-making task. It was also concluded that pilots have a preference for one particular approach to information acquisition. Application: Applications of outcomes of this research include the development of decision support systems that adapt to the information-processing capabilities and preferences of users.13 page(s

Heuristic-based information acquistion and decision making among pilots

Objective: This research was designed to examine the impact of heuristic-based approaches to the acquisition of task-related information on the selection of an optimal alternative during simulated in-flight decision making. Background: The work integrated features of naturalistic and normative decision making and strategies of information acquisition within a computer-based, decision support framework. Method: The study comprised two phases, the first of which involved familiarizing pilots with three different heuristic-based strategies of information acquisition: frequency, elimination by aspects, and majority of confirming decisions. The second stage enabled participants to choose one of the three strategies of information acquisition to resolve a fourth (choice) scenario. Results: The results indicated that task-oriented experience, rather than the information acquisition strategies, predicted the selection of the optimal alternative. It was also evident that of the three strategies available, the elimination by aspects information acquisition strategy was preferred by most participants. Conclusion: It was concluded that task-oriented experience, rather than the process of information acquisition, predicted task accuracy during the decision-making task. It was also concluded that pilots have a preference for one particular approach to information acquisition. Application: Applications of outcomes of this research include the development of decision support systems that adapt to the information-processing capabilities and preferences of users

Spreading of sediment due to underwater blasting and dredging:Field observations from quay Construction in Sisimiut, Greenland

The primary objectives of this study were to quantify the spreading of suspended sediment from underwater blasting and subsequent dredging of bedrock and to understand the physical processes governing the spreading of suspended sediment due to underwater blasting. The investigations were carried out in connection with the construction of a new quay at the existing harbour of Sisimiut, Greenland. Subsequent to the largest of a series of underwater blasts, the distribution of suspended sediment in the water column at and around the construction site was observed using a CTD (Conductivity, Temperature, Depth) equipped with a turbidity meter. The observations show that sediment was brought into suspension near the surface and at internal density gradients in the water column, where it became subject to prevailing flow conditions. The observations further show what was probably a turbidity current, flowing down the steeply sloping seabed away from the construction site. The spreading of sediment due to this turbidity current could not be assessed, but could have been considerable. Observations made using sediment traps over much of the period of construction show that the total spreading of sediment was roughly the same for blasting of bedrock and dredging of the blasted material and that much of the sediment that was brought into suspension settled near the construction site. Furthermore, these observations indicate that blasting leads to a wider spreading of sediment, but that dredging leads to a wider spreading of the organic part of the sediment. Almost all material less than 2 μm, including surficial clay minerals and much organic material, was transported away from the construction site and its vicinity, which could imply mobilization and export of pollutants. Environmental impacts of suspended sediment from underwater blasting, which could include coverage of the benthos or increased turbidity, can be managed by timing the blast favourably relative to currents, waves and stratification. It is argued that the environmental impact of blasting can be minimized by decreasing or maybe even increasing the spreading of sediment, depending on, e.g., the resilience of the flora and fauna and the surficial sediment and the pollution therein. Highlights • Sediment suspended near surface and internal density gradients in the water column. • Sediment transported by turbidity current down steeply sloping seabed. • Total spreading of sediment roughly the same for blasting and dredging. • Blasting leads to wider spreading of sediment. • Dredging leads to wider spreading of organic matter

Rigid vs non-rigid face and head motion in phone and tone perception

There is recent evidence that the visual concomitants, not only of the articulation of phones (consonants & vowels), but also of tones (fundamental frequency variations that signal lexical meaning in tone languages) facilitate speech perception. Analysis of speech production data from a Cantonese speaker suggests that the source of this perceptual information for tones involve rigid motion of the head rather than non-rigid face motion. A perceptual discrimination study was conducted using OPTOTRAK output in which rigid or non-rigid motion of the head could be presented independently, using two conditions: one in which words to be discriminated only differed in tone, and another in which they only differed in phone. The results suggest that non-rigid motion is the critical determinant for successful discrimination of phones, whereas both non-rigid and rigid motion are required for the discrimination of tones

The effect of dissolved barium on biogeochemical processes at cold seeps

A numerical model was applied to investigate and quantify the biogeochemical processes fueled by the expulsion of barium and methane-rich fluids in the sediments of a giant cold-seep area in the Derugin Basin (Sea of Okhotsk). Geochemical profiles of dissolved Ba2+, Sr2+, Ca2+, SO42−, HS−, DIC, I− and of calcium carbonate (CaCO3) were fitted numerically to constrain the transport processes and the kinetics of biogeochemical reactions. The model results indicate that the anaerobic oxidation of methane (AOM) is the major process proceeding at a depth-integrated rate of 4.9 μmol cm−2 a−1, followed by calcium carbonate and strontian barite precipitation/dissolution processes having a total depth-integrated rate of 2.1 μmol cm−2 a−1. At the low seepage rate prevailing at our study site (0.14 cm a−1) all of the rising barium is consumed by precipitation of barite in the sedimentary column and no benthic barium flux is produced. Numerical experiments were run to investigate the response of this diagenetic environment to variations of hydrological and biogeochemical conditions. Our results show that relatively low rates of fluid flow (<∼5 cm a−1) promote the dispersed precipitation of up to 26 wt% of barite and calcium carbonate throughout the uppermost few meters of the sedimentary column. Distinct and persistent events (several hundreds of years long) of more vigorous fluid flow (from 20–110 cm a−1), instead, result in the formation of barite-carbonate crusts near the sediment surface. Competition between barium and methane for sulfate controls the mineralogy of these sediment precipitates such that at low dissolved methane/barium ratios (<4–11) barite precipitation dominates, while at higher methane/barium ratios sulfate availability is limited by AOM and calcium carbonate prevails. When seepage rates exceed 110 cm a−1, barite precipitation occurs at the seafloor and is so rapid that barite chimneys form in the water column. In the Derugin Basin, spectacular barite constructions up to 20 m high, which cover an area of roughly 22 km2 and contain in excess of 5 million tons of barite, are built through this process. In these conditions, our model calculates a flux of barium to the water column of at least 20 μmol cm−2 a−1. We estimate that a minimum of 0.44 × 106 mol a−1 are added to the bottom waters of the Derugin Basin by cold seep processes, likely affecting the barium cycle in the Sea of Okhotsk

The perception and production of phones and tones: The role of rigid and non-rigid face and head motion

There is evidence, mostly with phones (consonants & vowels), that visual concomitants of articulation facilitate speech perception. Here the visual concomitants of lexical tone are considered. In tone languages fundamental frequency variations signal lexical meaning. In a word identification experiment with auditory-visual words differing only in tone, Cantonese perceivers performed above chance in a Visual Only condition. A subsequent study showed augmentation of word pair discrimination in noise in an Auditory-Visual compared to an Auditory Only condition for Cantonese, tonal Thai speakers, and even non-tone Australian speakers). The source of this perceptual information was sought in an OPTOTRAK production study of a Cantonese speaker. Functional Data Analysis (FDA) and Principal Component (PC) extraction suggests that the salient PCs to distinguish tones involve rigid motion of the head rather than non-rigid face motion. Results of a final perception study using OPTOTRAK output in which rigid or non-rigid motion could be presented independently in tone differing or phone differing conditions, suggests that non-rigid motion is most useful for the discrimination of phones, whereas rigid motion is most useful for the discrimination of tones