Environmental controls on the boron and strontium isotopic composition of aragonite shell material of cultured Arctica islandica

Ocean acidification, the decrease in ocean pH associated with increasing atmospheric CO2, is likely to impact marine organisms, particularly those that produce carbonate skeletons or shells. Therefore, it is important to investigate how environmental factors (seawater pH, temperature and salinity) influence the chemical compositions in biogenic carbonates. In this study we report the first high-resolution strontium (Sr-87 / Sr-86 and delta(88) / Sr-86) and boron (delta B-11) isotopic values in the aragonite shell of cultured Arctica islandica (A. islandica). The Sr-87/Sr-86 ratios from both tank water and shell samples show ratios nearly identical to the open ocean, which suggests that the shell material reflects ambient ocean chemistry without terrestrial influence. The Sr-84-Sr-87 double-spike-resolved shell delta(88) / Sr-86 and Sr concentration data show no resolvable change throughout the culture period and reflect no theoretical kinetic mass fractionation throughout the experiment despite a temperature change of more than 15 degrees C. The delta B-11 records from the experiment show at least a 5% increase through the 29-week culture season (January 2010-August 2010), with low values from the beginning to week 19 and higher values thereafter. The larger range in delta B-11 in this experiment compared to predictions based on other carbonate organisms (2-3 %) suggests that a species-specific fractionation factor may be required. A significant correlation between the Delta pH (pH(shell) - pH(sw)) and seawater pH (pH(sw)) was observed (R-2 = 0.35), where the pH(shell) is the calcification pH of the shell calculated from boron isotopic composition. This negative correlation suggests that A. islandica partly regulates the Delta pH of the extrapallial fluid. However, this proposed mechanism only explains approximately 35% of the variance in the delta B-11 data. Instead, a rapid rise in delta B-11 of the shell material after week 19, during the summer, suggests that the boron uptake changes when a thermal threshold of \u3e 13 degrees C is reached

Effect of microstructure and crystallography on sulfide stress cracking in API-5CT-C110 casing steel

Microstructure and crystallography have been characterized on an API-5CT-C110 casing steel. Regions near a crack, more distant from a crack, and from specimen with no cracks were analyzed through electron backscatter diffraction (EBSD). A higher proportion of low-angle grain boundaries appeared in the regions near the crack, while regions distant from cracks presented primarily high-angle grain boundaries. The high Kernel Average Misorientation value and more grains with higher Taylor factor emerged in areas beside cracks. The corrosion reactions observed in the cracks would be expected to promote crack growth

Effects of microstructure and crystallography on mechanical properties of cold-rolled SAE1078 pearlitic steel

The evolution of the microstructure and crystallography in SAE1078 pearlitic steel sheets under different cold-rolling reductions of up to 90% were quantified using transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). The mechanical properties were determined by tensile testing at room temperature. TEM analysis showed that the pearlite structure was obviously refined with the interlamellar spacing decreasing to about 57 nm at the rolling reduction of 90%. EBSD investigations indicated that the ferrite exhibited a {001}texture in the 90% cold-rolled pearlitic steel. The dislocations were mainly concentrated during cold rolling between the 10% and 70% reduction ratios as the average kernel average misorientation (KAM) angle increased from 0.75° to 1.20°. XRD examination revealed that a transformation from bcc to bct crystal structure of ferrite occurred at 90% rolling reduction due to the supersaturation of carbon. Significant augmentation in the ultimate tensile strength during cold rolling results from the boundary, dislocation, and solid solution strengthening mechanisms

Automatic summarization of rushes video using bipartite graphs

In this paper we present a new approach for automatic summarization of rushes, or unstructured video. Our approach is composed of three major steps. First, based on shot and sub-shot segmentations, we filter sub-shots with low information content not likely to be useful in a summary. Second, a method using maximal matching in a bipartite graph is adapted to measure similarity between the remaining shots and to minimize inter-shot redundancy by removing repetitive retake shots common in rushes video. Finally, the presence of faces and motion intensity are characterised in each sub-shot. A measure of how representative the sub-shot is in the context of the overall video is then proposed. Video summaries composed of keyframe slideshows are then generated. In order to evaluate the effectiveness of this approach we re-run the evaluation carried out by TRECVid, using the same dataset and evaluation metrics used in the TRECVid video summarization task in 2007 but with our own assessors. Results show that our approach leads to a significant improvement on our own work in terms of the fraction of the TRECVid summary ground truth included and is competitive with the best of other approaches in TRECVid 2007

Optically pumped 1.3 μm room-temperature InAs quantum-dot micro-disk lasers directly grown on (001) silicon

Direct integration of high-performance laser diodes on silicon will dramatically transform the world of photonics, expediting the progress toward low-cost and compact photonic integrated circuits (PICs) on the mainstream silicon platform. Here, we report, to the best of our knowledge, the first 1.3 μm room-temperature continuous-wave InAs quantum-dot micro-disk lasers epitaxially grown on industrial-compatible Si (001) substrates without offcut. The lasing threshold is as low as hundreds of microwatts, similar to the thresholds of identical lasers grown on a GaAs substrate. The heteroepitaxial structure employed here does not require the use of an absorptive germanium buffer and/or dislocation filter layers, both of which impede the efficient coupling of light from the laser active regions to silicon waveguides. This allows for full compatibility with the extensive silicon-on-insulator (SOI) technology. The large-area virtual GaAs (on Si) substrates can be directly adopted in various mature in-plane laser configurations, both optically and electrically. Thus, this demonstration represents a major advancement toward the commercial success of fully integrated silicon photonics

1.3-μm InAs quantum-dot micro-disk lasers on V-groove patterned and unpatterned (001) silicon

We report comparison of lasing dynamics in InAs quantum dot (QD) micro-disk lasers (MDLs) monolithically grown on V-groove patterned and planar Si (001) substrates. TEM characterizations reveal abrupt interfaces and reduced threading dislocations in the QD active regions when using the GaAs-on-V-grooved-Si template. The improved crystalline quality translates into lower threshold power in the optically pumped continuous-wave MDLs. Concurrent evaluations were also made with devices fabricated simultaneously on lattice-matched GaAs substrates. Lasing behaviors from 10 K up to room temperature have been studied systematically. The analyses spotlight insights into the optimal epitaxial scheme to achieve low-threshold lasing in telecommunication wavelengths on exact Si (001) substrates

The flow of information in trading: an entropy approach to market regimes

In this study, we use entropy-based measures to identify different types of trading behaviors.1We detect the return-driven trading using the conditional block entropy that dynamically reflects the “self-causality' of market return flows. Then we use the transfer entropy to identify the news-driven3trading activity that is revealed by the information flows from news sentiment to market returns. We argue that when certain trading behaviour becomes dominant or jointly dominant, the market will form a specific regime, namely return-, news- or mixed regime. Based on 11 years of news and market data, we find that the evolution of financial market regimes in terms of adaptive trading activities over the 2008 liquidity and euro-zone debt crises can be explicitly explained by the information flows. The proposed method can be expanded to make “causal' inferences on other types of economic phenomena

Applications of multi-variate Hawkes process to joint modelling of sentiment and market return events

To investigate the complex interactions between market events and investor sentiment, we employ a multivariate Hawkes process to evaluate dynamic effects among four types of distinct events: positive returns, negative returns, positive sentiment and negative sentiment. Using both intraday S&P 500 return data and Thomson Reuters News sentiment data from 2008 to 2014, we find: a) self-excitation is strong for all four types of events at 15 minutes time scale; b) there is a significant mutual-excitation between positive returns and positive sentiment, and negative returns and negative sentiment; c) decay of return events is almost twice as fast as sentiment events, which means market prices move faster than investor sentiment changes; d) positive sentiment shocks tend to generate negative price jumps; and e) the cross- excitation between positive and negative sentiments is stronger than their self-excitation. These findings provide further understanding of investor sentiment and its intricate interactions with market returns