Evolution of Sand Microstructure during Shear

Quantitative measurements of the local void ratio distribution are used to demonstrate how the microstructure throughout dilatant triaxial specimens of uniform fine quartz sand evolves during drained axial compression loading. Shear-induced increases in the mean of the local void ratio distribution initiate at the center of the specimen and migrate toward the ends of the specimen as axial strain increases. At any given strain, the mean of the local void ratio distribution is largest near the center of the specimen, reflecting the influence of end platen and membrane restraining effects. The results provide direct quantitative microstructure-based evidence that global or macro response, as conventionally used in interpreting specimen behavior, can be misleading as to the true material response. Implications of the test results on practical issues such as the location of local strain measurement systems are noted.     

Applying the value of equality unequally: Effects of value instantiations that vary in typicality.

Across 4 experiments, the authors investigated the role of value instantiation in bridging the gap between abstract social values and behavior in specific situations. They predicted and found that participants engaged in more egalitarian behavior (point allocation using the minimal group paradigm) after contemplating a typical instantiation of the value of equality compared to an atypical instantiation or a control condition that simply made the value salient. This effect occurred when participants generated reasons for valuing equality in the instantiation (Experiment 1) and when participants merely read about hypothetical examples of the instantiation context (Experiments 2, 3, and 4). Results across experiments indicated that the effect of prior instantiations was not mediated by changes in the abstract value; instead, the process of applying the abstract value was crucial (Experiment 4). Together, the experiments show that the process of applying an abstract value to a specific situation can be influenced by seemingly unrelated prior episodes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhodium Containing Magnetic Nanoparticles: Effective Catalysts for Hydrogenation and the 1,4-Addition of Boronic Acids

New efficient rhodium catalysts supported on superparamagnetic iron oxide nanoparticles (NPs) have been prepared using a novel method involving sulfonated triphenylphosphine ligands. They successfully promote the hydrogenation of olefins as well as the addition of arylboronic acids to dimethyl itaconate (ItMe₂) in water for up to 10 recycles. The catalysts were stable towards leaching of the metal complexes and were readily recovered by applying an external magnetic field.     

Using obstacle analysis to identify contingency requirements on an unpiloted aerial vehicle

This paper describes the use of Obstacle Analysis to identify anomaly handling requirements for a safety-critical, autonomous system. The software requirements for the system evolved during operations due to an on-going effort to increase the autonomous system’s robustness. The resulting increase in autonomy also increased system complexity. This investigation used Obstacle Analysis to identify and to reason incrementally about new requirements for handling failures and other anomalous events. Results reported in the paper show that Obstacle Analysis complemented standard safety-analysis techniques in identifying undesirable behaviors and ways to resolve them. The step-by-step use of Obstacle Analysis identified potential side effects and missing monitoring and control requirements. Adding an Availability Indicator and feature-interaction patterns proved useful for the analysis of obstacle resolutions. The paper discusses the consequences of these results in terms of the adoption of Obstacle Analysis to analyze anomaly handling requirements in evolving systems.     

Identity priming in English is compromised by phonological ambiguity.

If it takes longer to achieve a single phonological representation for inconsistent words (e.g., BOWL) than for consistent words (e.g., BENT), and if phonological coherence is pivotal to visual word recognition, then identity priming should depend on consistency. This hypothesis was evaluated in naming and lexical decision within a 4-field presentation sequence of mask-prime-mask-target. The prime-target stimulus onset asynchrony (SOA) was either 114 or 244 ms (with prime durations, respectively, of 43 and 129 ms). Four experiments compared identity primes such as BOWL and BENT, which were equated, on average, for total number of friendly and unfriendly neighbors, bigram frequency, and number of 1-letter-different neighbors. In both tasks, BENT primed itself better than BOWL primed itself, with the difference being larger at the shorter SOA. Word processing is constrained primarily by the rate of achieving a coherent phonological code. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance evaluation of TCP extensions on ATM over high bandwidthdelay product networks

Practical experiments in a satellite network environment assist in the design and understanding of future global networks. This article describes the practical experiences gained from TCP/IP on ATM networks over a high-speed satellite link and presents performance comparison studies of such networks with the same host/traffic configurations over local area and wide area networks. These comparison studies on the LAN, WAN, and satellite environments increase our understanding of the behavior of high-bandwidth networks. NASA's Advanced Communications Technology Satellite (ACTS), with its special characteristics and high data rate satellite channels, and the ACTS ATM Internetwork (AAI) were used in these experiments to deliver broadband traffic. Network performance tests were carried out using application-level software (Netspec) on SONET OC-3 (155.52 Mb/s) satellite links. Finally, we experimentally study the performance, efficiency, fairness, and aggressiveness of TCP Reno, TCP New Reno, and TCP SACK end hosts on ATM networks over high BDP networks     

Enhancement of a liquid-crystal modulator using an external-cavityVCSEL

We describe a vertical-cavity surface-emitting laser (VCSEL) and liquid-crystal modulator (LCM) system. The LCM controls external optical feedback into the VCSEL to produce a single switching element that has an enhanced contrast ratio compared to an LCM alone     

A Framework for Predictive Network Management of Predictive Mobile Networks

There is a trend toward the use of predictivesystems in communications networks. At the systems andnetwork management level predictive capabilities arefocused on anticipating network faults and performance degradation. Simultaneously, mobilecommunication networks are being developed withpredictive location and tracking mechanisms. Theinteractions and synergies between these systems presenta new set of problems. A new predictive network managementframework is developed and examined. The interactionbetween a predictive mobile network and the proposednetwork management system is discussed. The Rapidly Deployable Radio Network (RDRN) is used as aspecific example to illustrate theseinteractions.