Partitioning Method for Emergent Behavior Systems Modeled by Agent-Based Simulations

Used to describe some interesting and usually unanticipated pattern or behavior, the term emergence is often associated with time-evolutionary systems comprised of relatively large numbers of interacting yet simple entities. A significant amount of previous research has recognized the emergence phenomena in many real-world applications such as collaborative robotics, supply chain analysis, social science, economics and ecology. As improvements in computational technologies combined with new modeling paradigms allow the simulation of ever more dynamic and complex systems, the generation of data from simulations of these systems can provide data to explore the phenomena of emergence. To explore some of the modeling implications of systems where emergent phenomena tend to dominate, this research examines three simulations based on familiar natural systems where each is readily recognized as exhibiting emergent phenomena. To facilitate this exploration, a taxonomy of Emergent Behavior Systems (EBS) is developed and a modeling formalism consisting of an EBS lexicon and a formal specification for models of EBS is synthesized from the long history of theories and observations concerning emergence. This modeling formalism is applied to each of the systems and then each is simulated using an agent-based modeling framework. To develop quantifiable measures, associations are asserted: 1) between agent-based models of EBS and graph-theoretical methods, 2) with respect to the formation of relationships between entities comprising a system and 3) concerning the change in uncertainty of organization as the system evolves. These associations form the basis for three measurements related to the information flow, entity complexity, and spatial entropy of the simulated systems. These measurements are used to: 1) detect the existence of emergence and 2) differentiate amongst the three systems. The results suggest that the taxonomy and formal specification developed provide a workable, simulation-centric definition of emergent behavior systems consistent with both historical concepts concerning the emergence phenomena and modern ideas in complexity science. Furthermore, the results support a structured approach to modeling these systems using agent-based methods and offers quantitative measures useful for characterizing the emergence phenomena in the simulations

NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 21: Technological innovation and technical communications: Their place in aerospace engineering curricula. A survey of European, Japanese, and US Aerospace Engineers and Scientists

Aerospace engineers and scientists from Western Europe, Japan, and the United States were surveyed as part of the NASA/DoD Aerospace Knowledge Diffusion Research Project. Questionnaires were used to solicit their opinions regarding the following: (1) the importance of technical communications to their profession; (2) the use and production of technical communications; and (3) their views about the appropriate content of an undergraduate course in technical communications. The ability to communicate technical information effectively was very important to the aerospace engineers and scientists who participated in the study. A considerable portion of their working week is devoted to using and producing technical information. The types of technical communications used and produced varied within and among the three groups. The type of technical communication product used and produced appears to be related to respondents' professional duties. Respondents from the three groups made similar recommendations regarding the principles, mechanics, and on-the-job communications to be included in an undergraduate technical communications course for aerospace majors

Self-help materials for smoking relapse prevention: a process evaluation of the SHARPISH randomized controlled trial

Background: UK Stop Smoking Services are effective at assisting smokers to quit. However, smoking relapse rates are high, representing a significant public health problem. No effective interventions are currently available. This embedded qualitative process evaluation, within a randomised controlled trial of a self-help smoking relapse prevention intervention, aimed to understand patient perspectives in explaining the null trial finding, and to make recommendations for intervention development. Methods: The intervention was a British version of the ‘Forever Free’ self help booklets (SHARPISH - ISRCTN 36980856). The qualitative evaluation purposefully sampled 43 interview participants, triangulated with the views of 10 participants and 12 health professionals in focus groups. Data were thematically analysed. Results: Analysis revealed important variation in individual engagement with the self help booklets. Variation was interpreted by the meta-themes of ‘motivation for cessation’, and ‘positioning on information provision’, interacting with the theme of ‘mechanisms for information provision’. Conclusions: Targeting self help information towards those most motivated to engage may be beneficial, considering the social and cultural realities of individual’s lives. Individual preferences for the mechanisms of information delivery should be appraised when designing future interventions. Long term personalised follow up may be a simple step in improving smoking relapse rates

Nonergodic Behavior of Interacting Bosons in Harmonic Traps

We study the time evolution of a system of interacting bosons in a harmonic trap. In the low-energy regime, the quantum system is not ergodic and displays rather large fluctuations of the ground state occupation number. In the high energy regime of classical physics we find nonergodic behavior for modest numbers of trapped particles. We give two conditions that assure the ergodic behavior of the quantum system even below the condensation temperature.Comment: 11 pages, 3 PS-figures, uses psfig.st

Investigation of land ice-ocean interaction with a fully coupled ice-ocean model, Part 1: Model description and behavior

Antarctic ice shelves interact closely with the ocean cavities beneath them, with ice shelf geometry influencing ocean cavity circulation, and heat from the ocean driving changes in the ice shelves, as well as the grounded ice streams that feed them. We present a new coupled model of an ice stream-ice shelf-ocean system that is used to study this interaction. The model is capable of representing a moving grounding line and dynamically responding ocean circulation within the ice shelf cavity. Idealized experiments designed to investigate the response of the coupled system to instantaneous increases in ocean temperature show ice-ocean system responses on multiple timescales. Melt rates and ice shelf basal slopes near the grounding line adjust in 12 years, and downstream advection of the resulting ice shelf thinning takes place on decadal timescales. Retreat of the grounding line and adjustment of grounded ice takes place on a much longer timescale, and the system takes several centuries to reach a new steady state. During this slow retreat, and in the absence of either an upward-or downward-sloping bed or long-term trends in ocean heat content, the ice shelf and melt rates maintain a characteristic pattern relative to the grounding line

Self-help educational booklets for the prevention of smoking relapse following smoking cessation treatment: a randomized controlled trial.

AIMS: Most people who quit smoking for a short term will return to smoking again in 12 months. We tested whether self-help booklets can reduce relapse in short-term quitters after receiving behavioural and pharmacological cessation treatment. DESIGN: A parallel-arm, pragmatic individually randomized controlled trial. SETTING: Smoking cessation clinics in England. Participants People who stopped smoking for 4 weeks after receiving cessation treatment in stop smoking clinics. INTERVENTION: Participants in the experimental group (n=703) were mailed eight booklets, each of which taught readers how to resist urges to smoke. Participants in the control group (n=704) received a leaflet currently used in practice. MEASUREMENTS: The primary outcome was prolonged, carbon monoxide-verified abstinence from months 4 to 12. The secondary outcomes included 7-day self-reported abstinence at 3 and 12 months. Mixed-effects logistic regression was used to estimate treatment effects and to investigate possible effect modifying variables. FINDINGS: There were no statistically significant differences between the groups in prolonged abstinence from months 4 to 12 (36.9% versus 38.6%; odds ratio 0.93, 95% confidence interval 0.75-1.16; P=0.524). In addition, there were no significant differences between the groups in any secondary outcomes. However, people who reported knowing risky situations for relapse and using strategies to handle urges to smoke were less likely to relapse. CONCLUSIONS: In people who stop smoking successfully with behavioural support, a comprehensive self-help educational programme to teach people skills to identify and respond to high-risk situations for return to smoking did not reduce relapse

The Effects of Damage on Hydrogen-Implant-Induced Thin-Film Separation from Bulk Silicon Carbide

Exfoliation of Sic by hydrogen implantation and subsequent annealing forms the basis for a thin-film separation process which, when combined with hydrophilic wafer bonding, can be exploited to produce silicon-carbide-on-insulator, SiCOI. Sic thin films produced by this process exhibit unacceptably high resistivity because defects generated by the implant neutralize electrical carriers. Separation occurs because of chemical interaction of hydrogen with dangling bonds within microvoids created by the implant, and physical stresses due to gas-pressure effects during post-implant anneal. Experimental results show that exfoliation of Sic is dependent upon the concentration of implanted hydrogen, but the damage generated by the implant approaches a point when exfoliation is, in fact, retarded. This is attributed to excessive damage at the projected range of the implant which inhibits physical processes of implant-induced cleaving. Damage is controlled independently of hydrogen dosage by elevating the temperature of the SiC during implant in order to promote dynamic annealing. The resulting decrease in damage is thought to promote growth of micro-cracks which form a continuous cleave. Channeled H{sup +} implantation enhances the cleaving process while simultaneously minimizing residual damage within the separated film. It is shown that high-temperature irradiation and channeling each reduces the hydrogen fluence required to affect separation of a thin film and results in a lower concentration of defects. This increases the potential for producing SiC01 which is sufficiently free of defects and, thus, more easily electrically activated

Three Gravitationally Lensed Supernovae Behind CLASH Galaxy Clusters

We report observations of three gravitationally lensed supernovae (SNe) in the Cluster Lensing And Supernova survey with Hubble (CLASH) Multi-Cycle Treasury program. These objects, SN CLO12Car (z = 1.28), SN CLN12Did (z = 0.85), and SN CLA11Tib (z = 1.14), are located behind three different clusters, MACSJ1720.2+3536 (z = 0.391), RXJ1532.9+3021 (z = 0.345), and Abell 383 (z = 0.187), respectively. Each SN was detected in Hubble Space Telescope (HST) optical and infrared images. Based on photometric classification, we find that SNe CLO12Car and CLN12Did are likely to be Type Ia supernovae (SNe Ia), while the classification of SN CLA11Tib is inconclusive. Using multi-color light-curve fits to determine a standardized SN Ia luminosity distance, we infer that SN CLO12Car was approximately 1.0 +/- 0.2 mag brighter than field SNe Ia at a similar redshift and ascribe this to gravitational lens magnification. Similarly, SN CLN12Did is approximately 0.2 +/- 0.2 mag brighter than field SNe Ia. We derive independent estimates of the predicted magnification from CLASH strong+weak lensing maps of the clusters: 0.83 +/- 0.16 mag for SN CLO12Car, 0.28 +/- 0.08 mag for SN CLN12Did, and 0.43 +/- 0.11 mag for SN CLA11Tib. The two SNe Ia provide a new test of the cluster lens model predictions: we find that the magnifications based on the SN Ia brightness and those predicted by the lens maps are consistent. Our results herald the promise of future observations of samples of cluster-lensed SNe Ia (from the ground or space) to help illuminate the dark-matter distribution in clusters of galaxies, through the direct determination of absolute magnifications.Comment: ApJ in pres

Investigation of land ice-ocean interaction with a fully coupled ice-ocean model: Part 2. Sensitivity to external forcings

A coupled ice stream-ice shelf-ocean cavity model is used to assess the sensitivity of the coupled system to far-field ocean temperatures, varying from 0.0 to 1.8C, as well as sensitivity to the parameters controlling grounded ice flow. A response to warming is seen in grounding line retreat and grounded ice loss that cannot be inferred from the response of integrated melt rates alone. This is due to concentrated thinning at the ice shelf lateral margin, and to processes that contribute to this thinning. Parameters controlling the flow of grounded ice have a strong influence on the response to sub-ice shelf melting, but this influence is not seen until several years after an initial perturbation in temperatures. The simulated melt rates are on the order of that observed for Pine Island Glacier in the 1990s. However, retreat rates are much slower, possibly due to unrepresented bedrock features