Sub‐Micron Anisotropic InP‐based III–V Semiconductor Material Deep Etching for On‐Chip Laser Photonics Devices

Two InP‐based III–V semiconductor etching recipes are presented for fabrication of on‐chip laser photonic devices. Using inductively coupled plasma system with a methane free gas chemistry of chlorine and nitrogen at a high substrate temperature of 250 °C, high aspect ratio, anisotropic InP‐based nano‐structures are etched. Scanning electron microscopy images show vertical sidewall profile of 90° ± 3°, with aspect ratio as high as 10. Atomic Force microscopy measures a smooth sidewall roughness root‐mean‐square of 2.60 nm over a 3 × 3 μm scan area. The smallest feature size etched in this work is a nano‐ring with inner diameter of 240 nm. The etching recipe and critical factors such as chamber pressure and the carrier plate effect are discussed. The second recipe is of low temperature (?10 °C) using Cl₂ and BCl₃ chemistry. This recipe is useful for etching large areas of III–V to reveal the underlying substrate. The availability of these two recipes has created a flexible III–V etching platform for fabrication of on‐chip laser photonic devices. As an application example, anisotropic InP‐based waveguides of 3 μm width are fabricated using the Cl₂ and N₂ etch recipe and waveguide loss of 4.5 dB mm^?1 is obtained.

     

Nano-structured solid oxide fuel cell design with superior power output at high and intermediate operation temperatures

A solid oxide fuel cell (SOFC) with a thin-film yttria-stabilized zirconia (YSZ) electrolyte was developed and tested. This novel SOFC shows a similar multilayer set-up as other current anode-supported SOFCs and is composed of a Ni/8YSZ anode, a gas-tight 8YSZ electrolyte layer, a dense Sr-diffusion barrier layer and a LSCF cathode. To increase the power density and lower the SOFC operating temperature, the thickness of the electrolyte layer was reduced from around 10 μm in current cells to 1 μm, using a nanoparticle deposition method. By using the novel 1 μm electrolyte layer, the current density of our SOFC progressed to 2.7, 2.1 and 1.6 A/cm² at operation temperatures of 800, 700 and 650°C, respectively, and out-performs all similar cells reported to date in the literature. An important consideration is also that cost-effective dip-coating and spin-coating methods are applied for the fabrication of the thin-film electrolyte. Processing of 1 μm layers on the very porous anode substrate material was initially experienced as very difficult and therefore 8YSZ nanoparticle coatings were developed and optimized on porous 8YSZ model substrates and transferred afterwards to regular anode substrates. In this paper, the preparation of the novel SOFC is shown and its morphology is illustrated with high resolution SEM pictures. Further, the performance in a standard SOFC test is demonstrated.     

Asymmetric multivariate normal mixture GARCH

An asymmetric multivariate generalization of the recently proposed class of normal mixture GARCH models is developed. Issues of parametrization and estimation are discussed. Conditions for covariance stationarity and the existence of the fourth moment are derived, and expressions for the dynamic correlation structure of the process are provided. In an application to stock market returns, it is shown that the disaggregation of the conditional (co)variance process generated by the model provides substantial intuition. Moreover, the model exhibits a strong performance in calculating out-of-sample Value-at-Risk measures.     

Remotely sensed surface water extent as an indicator of short-term changes in ecohydrological processes in sub-Saharan Western Africa

The highly variable rainfall in the arid and semi-arid regions of sub-Saharan Western Africa drives both surface water availability and vegetation cover. Recent studies have established linkages between rainfall and vegetation cover at local to regional scales, but no study related yet remote sensing derived rainfall and vegetation cover to the available surface water. A new dataset based on SPOT VEGETATION (VGT) represents surface water bodies (SWB) in the arid and semi-arid regions of sub-Saharan Western Africa. Water bodies represent the integrated hydrological response of a catchment, and changes in their spatial extent involve complex interactions at the catchment scale. We analyzed time series of remotely sensed vegetation cover, rainfall and surface water extent for the period 1999–2008, and could detect and statistically demonstrate the links between these biophysical variables. Our findings for two regions in Mali and Burkina Faso suggest that vegetation cover is positively related to the amount of available surface water for those catchments that are mainly covered by annual plants. The observed relationships between remotely sensed variables allow developing ecological indicators that can indicate short-term changes in arid and semi-arid ecosystems at local to regional scales.     

Patient views of adverse events: comparisons of self-reported healthcare staff attitudes with disclosure of accident information

In the present paper, we report results of surveys in 2003 in Japan and Denmark about patients' views about adverse events, focusing on the actions of healthcare staff involved in a medical accident. Results show that patients were more likely to indicate negative expectations to a doctor's reactions after a medical accident when asked in general terms than when asked in relation to concrete case stories. When asked in general terms, 66% (47%) of Japanese (Danish) respondents expected that doctors sometimes hold back on providing information to patients about a medical accident, while 37% (7%) did so when asked about a concrete, mild-outcome case. We examine some possible reasons for the relatively high level of distrust of Japanese patients, and we discuss whether the seemingly lower level of disclosure in Japan than in Denmark and the negative stories in the Japanese press may have an impact. We also suggest some implications for introducing a patient-centred or customer-centred approach to risk management in healthcare and other domains.     

Hybrid routing in ad hoc networks with a dynamic virtual backbone

Virtual backbone routing (VBR) is a scalable hybrid routing framework for ad hoc networks, which combines local proactive and global reactive routing components over a variable-sized zone hierarchy. The zone hierarchy is maintained through a novel distributed virtual backbone maintenance scheme, termed the distributed database coverage heuristic (DDCH), also presented in this paper. Borrowing from the design philosophy of the zone routing protocol, VBR limits the proactive link information exchange to the local routing zones only. Furthermore, the reactive component of VBR restricts the route queries to within the virtual backbone only, thus improving the overall routing efficiency. Our numerical results suggest that the cost of the hybrid VBR scheme can be a small fraction of that of either one of the purely proactive or purely reactive protocols, with or without route caching. Since the data routes do not necessarily pass through the virtual backbone nodes, traffic congestion is considerably reduced. Yet, the average length of the VBR routes tends to be close to optimal. Compared with the traditional one-hop hierarchical protocols, our results indicate that, for a network of moderate to large size, VBR with an optimal zone radius larger than one can significantly reduce the routing traffic. Furthermore, we demonstrate VBR's improved scalability through analysis and simulations.     

Gossip-based ad hoc routing

Many ad hoc routing protocols are based on some variant of flooding. Despite various optimizations of flooding, many routing messages are propagated unnecessarily. We propose a gossiping-based approach, where each node forwards a message with some probability, to reduce the overhead of the routing protocols. Gossiping exhibits bimodal behavior in sufficiently large networks: in some executions, the gossip dies out quickly and hardly any node gets the message; in the remaining executions, a substantial fraction of the nodes gets the message. The fraction of executions in which most nodes get the message depends on the gossiping probability and the topology of the network. In the networks we have considered, using gossiping probability between 0.6 and 0.8 suffices to ensure that almost every node gets the message in almost every execution. For large networks, this simple gossiping protocol uses up to 35% fewer messages than flooding, with improved performance. Gossiping can also be combined with various optimizations of flooding to yield further benefits. Simulations show that adding gossiping to AODV results in significant performance improvement, even in networks as small as 150 nodes. Our results suggest that the improvement should be even more significant in larger networks.     

Considering Prework on Industrial Projects

Prefabrication, preassembly, modularization, and off-site fabrication, collectively termed as prework have become more viable with recent advances in design and information technologies. These construction methods offer a substantial opportunity to improve project performance when circumstances merit. Successful implementation of these methods on a particular project requires systematic analysis and early decision making based on specific factors of the project. This paper identifies those factors influencing decisions on the use of prework, and current industry practices for evaluating the applicability of prework on industrial projects. It then presents a decision framework to assist industry practitioners with evaluating the applicability of prework on their project, and describes a computerized tool to aid project teams in the decision-making process. The developed framework and tool are useful and effective in the decision-making process, and easy to use, as validated by practitioners in the industry.     

A Clinical Trial to Test the Feasibility of a Telehealth Psychoeducational Intervention for Persons With Schizophrenia and Their Families: Intervention and 3-Month Findings.

Objective: To evaluate the feasibility of a telehealth psychoeducation intervention for persons with schizophrenia and their family members. Study Design: Randomized controlled trial. Participants: 30 persons with schizophrenia and 21 family members or other informal support persons. Interventions: Web-based psychoeducation program that provided online group therapy and education. Main Outcome Measures: Measures for persons with schizophrenia included perceived stress and perceived social support; for family members, they included disease-related distress and perceived social support. Results: At 3 months, participants with schizophrenia in the intervention group reported lower perceived stress (p = .04) and showed a trend for a higher perceived level of social support (p = .06). Conclusions: The findings demonstrate the feasibility and impact of providing telehealth-based psychosocial treatments, including online therapy groups, to persons with schizophrenia and their families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automated Quality Assessment of Stone Aggregates Based on Laser Imaging and a Neural Network

An automated quality assessment technique is proposed for rapidly detecting excessive size variations during the production of stone aggregates. The system uses a laser profiler to scan collections of aggregate particles and obtain three-dimensional data points on the particle surfaces. For computational efficiency, the resulting data are converted into digital images. Wavelet transforms are then applied to the images to extract features indicative of the material gradation. These wavelet-based features are used as inputs to an artificial neural network, which is trained to classify the aggregate sample. Taken together, these components form a neural network-based classification system that can determine whether or not an aggregate product is in compliance with a given specification. Verification tests show that this approach could potentially help to determine, in an accurate and fast (real-time) manner, when adjustments or repairs to the production equipment are needed.