Emergent Collective Dynamics with Applications in Bridge Engineering and Social Networks

This thesis presents several novel results on the nonlinear and emergent collective dynamics of crowds and populations in complex systems. Though, historically, the list of suspension bridges destabilized by pedestrian collective motion is long, the phenomenon still needs to be fully understood, especially regarding the effect of human-to-human interactions on the structure, and often incorrectly explained using synchronization theory. We present a simple general formula that quantifies the effect of pedestrian effective damping of a suspension bridge and illustrate it by simulating three mathematical models, including one with a strong propensity for synchronization. Despite the subtle effects of gait strategies in determining precise instability thresholds, our results show that average negative damping is always the trigger of pedestrian-induced high-amplitude lateral vibration of suspension bridges. Furthermore, we show that human-to-human interactions of heterogeneous pedestrians can trigger the instability of a bridge more effectively than crowds of identical pedestrians. We will also discuss the role of crowd heterogeneity in possible phase pulling between pedestrians and bridge motion. We also develop a model for the evolution of toxic memes on 4chan and report a significant influence on Twitter’s anti-vaccine conspiracy discourse over a nine-year period. We show that 4chan topics evolve according to an emergent process mathematically similar to classic reinforcement learning methods, tending to maximize the expected toxicity of future discourse. We demonstrate that these topics can invade Twitter and persist in an endemic state corresponding to the associated spreading rate and initial distribution of post rates and coexisting with a higher-traffic regime of dynamics. We discuss the implication of this result for preventing large-scale disinformation campaigns

Complementary Effect of Electrical and Inhibitory Coupling in Bursting Synchronization

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Developing a monitoring and verification plan with reference to the Australian Otway CO2 pilot project

The Australian Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) is currently injecting 100,000 tons of CO{sub 2} in a large-scale test of storage technology in a pilot project in southeastern Australia called the CO2CRC Otway Project. The Otway Basin, with its natural CO{sub 2} accumulations and many depleted gas fields, offers an appropriate site for such a pilot project. An 80% CO{sub 2} stream is produced from a well (Buttress) near the depleted gas reservoir (Naylor) used for storage (Figure 1). The goal of this project is to demonstrate that CO{sub 2} can be safely transported, stored underground, and its behavior tracked and monitored. The monitoring and verification framework has been developed to monitor for the presence and behavior of CO{sub 2} in the subsurface reservoir, near surface, and atmosphere. This monitoring framework addresses areas, identified by a rigorous risk assessment, to verify conformance to clearly identifiable performance criteria. These criteria have been agreed with the regulatory authorities to manage the project through all phases addressing responsibilities, liabilities, and to assure the public of safe storage

Evaluation of Visible Diffuse Reflectance Spectroscopy in Liver Tissue: Validation of Tissue Saturations Using Extracorporeal Circulation

Significance: Real-time information about oxygen delivery to the hepatic graft is important to direct care and diagnose vascular compromise in the immediate post-transplant period. Aim: The current study was designed to determine the utility of visible diffuse reflectance spectroscopy (vis-DRS) for measuring liver tissue saturation in vivo. Approach: A custom-built vis-DRS probe was calibrated using phantoms with hemoglobin (Hb) and polystyrene microspheres. Ex vivo (extracorporeal circulation) and in vivo protocols were used in a swine model (n=15) with validation via blood gas analysis. Results: In vivo absorption and scattering measured by vis-DRS with and without biliverdin correction correlated closely between analyses. Lin’s concordance correlation coefficients are 0.991 for μa and 0.959 for μs\u27. Hb measured by blood test and vis-DRS with (R2=0.81) and without (R2=0.85) biliverdin correction were compared. Vis-DRS data obtained from the ex vivo protocol plotted against the PO2 derived from blood gas analysis showed a good fit for a Hill coefficient of 1.67 and P50=34  mmHg (R2=0.81). A conversion formula was developed to account for the systematic deviation, which resulted in a goodness-of-fit (R2=0.76) with the expected oxygen dissociation curve. Conclusions: We show that vis-DRS allows for real-time measurement of liver tissue saturation, an indicator for liver perfusion and oxygen delivery

The SSERC Primary Cluster Programme in Science and Technology – impact on teaching and learning

This paper considers the findings of a recent multi-method research project that assessed the impact of a national Career Long Professional Learning (CLPL) programme, which suggest that teacher CLPL, particular in science and technology education, is particularly effective when it adopts a collaborative mentoring approach deployed across school clusters. This model is underpinned by collaborative professional dialogue, action research and a focus on promoting teachers' confidence and expertise in science and technology using practical skills as a vehicle. We examine the model adopted by the programme, drawing on research evidence in the literature on effective professional learning for teachers and, in particular, apply Desimone’s (2009) conceptual framework. The paper identifies key components of the programme responsible for its effectiveness and concludes by reflecting on the implications of the findings for tackling the challenge of promoting science literacy and attainment. Surveys of >12000 pupils have shown, inter alia, that the programme encourages the preservation of positive pupil attitudes towards science

Chemical Reaction Dynamics at Surfaces

Contains reports on two research projects with publication lists in each section.Joint Services Electronics Program Contract DAAL03-89-C-0001MIT Energy Laboratory Synthetic Fuels CenterNational Science Foundation Grant CHE 85-08734Petroleum Research Fund Contract 19014-AC

Emergence of the London Millennium Bridge instability without synchronisation.

The pedestrian-induced instability of the London Millennium Bridge is a widely used example of Kuramoto synchronisation. Yet, reviewing observational, experimental, and modelling evidence, we argue that increased coherence of pedestrians' foot placement is a consequence of, not a cause of the instability. Instead, uncorrelated pedestrians produce positive feedback, through negative damping on average, that can initiate significant lateral bridge vibration over a wide range of natural frequencies. We present a simple general formula that quantifies this effect, and illustrate it through simulation of three mathematical models, including one with strong propensity for synchronisation. Despite subtle effects of gait strategies in determining precise instability thresholds, our results show that average negative damping is always the trigger. More broadly, we describe an alternative to Kuramoto theory for emergence of coherent oscillations in nature; collective contributions from incoherent agents need not cancel, but can provide positive feedback on average, leading to global limit-cycle motion

The Grizzly, October 28, 1996

Alice Parker Conducts College Choir • A Question on Diversity • Security Flash • New Curriculum for Comm. Arts • Opinions: More on the Gun Control Debate; The Debates of Nothingness; How Open Are You? Voting for Dole in \u2796; I\u27m Voting for Dennis Miller • Letters from Ireland • University of Pennsylvania Anthropologist to Speak on Maya and Aztecs • Spotlight: Karl Yergey • Plugging-In to the Benefits of E-mail • Looking for a few Good Dangerous Minds: Education Club Re-activates • Field Hockey Drops One To American • Women\u27s Soccer Nets First Conference Win • Volleyball Loses Two • Men\u27s Soccer Defeats Dickinson 2-0 • Kings Point Trips Up Ursinushttps://digitalcommons.ursinus.edu/grizzlynews/1389/thumbnail.jp

Development of Drugs for Nontuberculous Mycobacterial Disease:Clinicians’ Interpretation of a US Food and Drug Administration Workshop

The US Food and Drug Administration convened a workshop to discuss clinical trial design challenges and considerations related to the treatment of nontuberculous mycobacterial pulmonary disease, to include topics such as clinical trial end points, duration, and populations. The clinicians participating in the meeting provide here their interpretation of the discussion, which included US Food and Drug Administration and industry representatives. The treatment of nontuberculous mycobacterial pulmonary disease typically includes multiple antibiotics for a prolonged period and can be difficult to tolerate; there is a great need for new treatment options. Most individuals have a microbiologic response to therapy, but data correlating decreasing bacillary load with patient-reported outcomes or measured functional improvement are lacking. Accordingly, trial designs for new therapeutic agents should incorporate both microbiologic and clinical outcome measures and select appropriate study candidates with capacity for measurable change of such outcome measures. The need for shorter study designs, early primary end points, and placebo control arms was highlighted during the workshop