Past IMC Colloquium Abstracts
IMC Colloquium Series: "Simulation Model Calibration and Prediction Using Outputs From Multi-Fidelity Simulators"
Derek Bingham
Canada Research Chair - Industrial Statistics
Department of Statistics and Actuarial Science, Simon Fraser University
Date: Nov 30, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Computer simulators are used widely to describe physical processes in lieu of physical observations. In some cases, more than one computer code can be used to explore the same physical system - each with different degrees of fidelity. In this work, we combine field observations and model runs from deterministic multi-fidelity computer simulators to build a predictive model for the real process. The resulting model can be used to perform sensitivity analysis for the system and make predictions with associated measures of uncertainty. Our approach is Bayesian and will be illustrated through a simple example, as well as a real application in predictive science at the Center for Radiative Shock Hydrodynamics at the University of Michigan.
Video Archive
IMC Colloquium Series: "Portfolio Theory and Ecology?"
Kenneth Kasa
Professor
Department of Economics, Simon Fraser University
Date: Nov 16, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Biologists and economists have always borrowed from each other. Darwin famously credited Malthus for inspiration in The Origin of Species. Marshall argued persuasively that economists should strive to be more like biologists, and less like physicists. More recently, since the 1970s game theorists in both biology and economics have jointly developed many useful ideas and concepts.
This talk will discuss an even more recent example of cross-fertilization, namely, the application of ideas from portfolio theory to quantify the benefits of biodiversity. The analogies seem obvious - species can be viewed as "stocks", which yield a flow of "returns". Due to genetic, environmental, and climatic idiosyncrasies, these returns are imperfectly correlated, yielding potential gains from diversification, i.e., gains from biodiversity. Most of the talk will discuss the dangers of pushing this analogy too far, by highlighting some of the implicit assumptions in traditional portfolio theory that may be questionable in a biological context. However, the talk will conclude by discussing recent efforts by economists to formalize the concepts of ambiguity and robustness, which may lead to a more reasonable application of portfolio theory in biology.Video Archive
IMC Colloquium Series: "Linking freshwater biodiversity to ecosystem stability and function"
Jonathan W. Moore
Liber Ero Chair
Department of Biological Sciences, Simon Fraser University
Date: Nov 09, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
This talk will present two related research directions focused on quantifying the causes and consequences of freshwater biodiversity. First, I will examine how diversity contributes to stability using studies of Pacific salmon in large western North American watersheds, such as the Snake, Skeena, and Fraser. In theory, diversity can increase stability via the portfolio effect, whereby asynchronous dynamics of assets can buffer the aggregate. Financial portfolio theory can offer a quantitative framework to apply to ecological systems, such as salmon. Migratory salmon exhibit striking population diversity, with a diverse array of life-history adaptations. This salmon population diversity can lead to increased stability of catches that integrate across multiple populations. In the Snake River, a more impacted large watershed in the United States, our recent research uncovered insidious biodiversity loss, where salmon populations have not decreased in number, but have decreased in their response diversity, thereby compromising stability. Second, I will investigate how freshwater biodiversity contributes to key ecosystem processes such as the cycling of nutrients such as nitrogen or phosphorus. Through linking large datasets on fish and invertebrate communities with trait-datasets, my collaborator and I seek to map and illuminate patterns of biodiversity-ecosystem function. Together, this research provides insight into the importance of freshwater biodiversity.
Video Archive
IMC Colloquium Series: Factors Associated with Antiretroviral adherence among HIV and Adults in BC
Robert Hogg
Date: Oct 19, 2012
Time: 11:30 - 12:30
Room: ASB10900
Abstract
TBA
Video Archive
IMC Colloquium Series:"Oceans of loss or a sea of choice: transforming science into action"
Nicholas K. Dulvy
Canadian Research Chair in Marine Biodiversity and Conservation
Department of Biological Sciences, Simon Fraser University
Date: Oct 05, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
TBA
Video Archive
IMC Colloquium Series "Simplified Models of Locomotion: A little tells us a lot"
Shawn O'Connor
Department of Biomedical Physiology & Kinesiology
Date: Mar 23, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
To model human locomotion, the remarkable complexity of the neuromuscular system must be reduced down to a tractable level of study. Even among these "simplified" models, there is an enormous range of complexity, from models with only one parameter to those with several hundred. The simplest among these provide fundamental insight into how we move but often fail to reproduce realistic measurements made of human subjects or reproduced by the most complex models. Is complexity necessary for realism? I will first explore how key features of human gait may be reproduced even in a simple bipedal model when compliance is added to the legs. This model can walk, run, and even skip and this variety of gaits is produced by varying only two stiffness parameters and adjusting initial conditions. The compliant leg behavior essentially models work performed by muscle and tendon and predicts realistic energetic costs measured in human walking. I will then demonstrate how other simple models of locomotion may be used to generate testable hypotheses that are verified with human experiments. Simple three-dimensional walking models indicate that fore-aft walking dynamics may be self-stabilizing, whereas lateral motion is unstable and requires active control. These findings led us to predict that humans might rely less on vision for fore-aft balance than mediolateral. We tested whether humans exhibit such direction-dependent control by applying low-frequency perturbations to the visual field through virtual reality and measuring balance corrections during treadmill walking. We found walking balance to be nearly ten times more sensitive to mediolateral visual perturbations than fore-aft.
Video Archive
IMC Colloquium Series "Modeling Electronic Dance Music: Intelligent Generation using Human Transcription and Analysis"
Arne Eigenfeldt
School for the Contemporary Arts
Date: Mar 09, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Artist Philip Galanter proposes that that generative art "refers to any art practice where the artist uses a system, such as a set of natural language rules, a computer program, a machine, or other procedural invention, which is set into motion with some degree of autonomy contributing to or resulting in a completed work of art." Placed within the paradigm of electroacoustic music, generative music is, therefore, music that either uses a computer to autonomously generate the resulting music, and/or electroacoustic means - such as a synthesizer or sampler - to realize its results. One important aspect of generative music is that it is based within composition, rather than improvisation; in fact, I have proposed the concept of real-time composition to further discriminate its compositional basis from the improvisational elements of live electroacoustic music.
When creating a generative system, rules are required to limit the possible choices; in most cases, these rules are used to generate new compositions in the style of the composer. One difficulty with generative systems is validating the success of the system - in other words, whether the system has interpreted the rules correctly, or whether the rules themselves accurately model the desired style. In the above mentioned system, it is really only the creator of the system that can make this judgement: listeners can reject the musical result, but the system's creator can argue that they are making aesthetic judgements of the music, rather than the system. However, if the aim of the system is to create music consistent within a given genre, it is possible to judge the success of the system - both artistically and practically - by the relationship of its output to the original corpus.
The Generative Electronica Research Project, part of ongoing research into musical metacreation - the potential of endowing machines with creative behavior - is pursuing the potential of creating software that generates electronic dance music in specific styles. We have selected 100 complete musical examples in the genres of Breakbeat, House, Drum & Bass, and Dubstep, and are using a combination of machine and human analysis of these works to derive rulesets, which, in turn, are used to generate new music consistent within the genres. Unlike the work of David Cope, who used a set corpus of existing music by composers such as Bach, Mozart, Beethoven, and Joplin to create new compositions through recombinance - stitching together music from given examples - we are using generative methods - including probabilistic methods and genetic algorithms - to create new music.
This presentation will discuss how our methods differ from other generative music systems, and other music information retrieval (MIR) programs, and present musical examples of our ongoing research.
BIO
Arne Eigenfeldt is a composer of live electroacoustic music, and a researcher into intelligent realtime music systems. His music has been performed around the world, and his collaborations range from Persian Tar masters to contemporary dance companies to musical robots. His research has been presented at conferences such as ICMC, NIME, SEAMUS, ISMIR, EMS, and SMC. He is an associate professor of music and technology at Simon Fraser University, Canada, and is the co-director of the MetaCreation research group (metacreation.net), which aims to endow computers with creative behaviour.
Video Archive
IMC Colloquium Series: "Understanding Type IV pilus structure"
Lisa Craig
Department of Molecular Biology and Biochemistry
Date: Feb 24, 2012
Time: 12:30 - 13:30
Room: ASB10900
WebSite: Click Here
Abstract
Type IV pili are hair-like filaments on the surfaces of a number of pathogenic bacteria. These pili mediate many critical functions in bacterial colonization and survival in the host and are thus key virulence factors. They are comprised of thousands of copies of a single subunit, pilin. We have used x-ray crystallography to obtain atomic resolution structures of the pilin subunits, and electron microscopy, deuterium exchange mass spectrometry and computational modeling to determine the structure of the pilus filaments and to predict the mechanism by which these pili are assembled. I will discuss this methodology and present our results for Type IV pili from several bacterial pathogens including Neisseria gonorrhoeae and Vibrio cholera.
Video Archive
IMC Colloquium Series: "Ferry Scheduling - Models and algorithms"
Abraham Punnen
Department of Mathematics
Date: Feb 10, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
We discuss new integer programming models for routing and scheduling of a heterogeneous fleet of ferries used in inter-island traffic. Also we report new heuristic approaches and results of a case study. Our models and algorithms resulted in superior outcomes in terms of solution quality and cost savings.
Video Archive
IMC Colloquium Series: "Applications for a 3-D, individual cell based model of cell movement and visualization in multicellular systems, fashioned on mechanical and chemical cell interactions"
Eirikur Palsson
Department of Biology
Date: Jan 27, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
A three-dimensional mathematical model was developed to explore by simulation and visualization how cell signaling, adhesion, motility, and stiffness affect cell movements and growth in multicellular systems. Here I show the ramifications of these interactions for a number of different biological systems and demonstrate that the emerging cell patterns in these multicellular systems are distinctively different from that of an individual cell. The building blocks of the model are individual deformable ellipsoidal cells, where the cell response, both mechanical and chemical, depends on its internal parameter state (cell adhesion and stiffness) and on external cues from the neighboring cells, extracellular matrix, and chemical signals. Cell movement and deformation is then calculated from the equations of motion using the total force acting on each cell, ensuring that forces are balanced. The model uses experimentally measured cellular characteristics, can simulate over 100,000 cells, and is adaptable to many different systems. I will show simulations of cell movements and cell signaling in Dictyostelium discoideum and explore cell sorting and chemotaxis. Simulations of paracrine signaling interactions between macrophages and tumor cells show how these interactions facilitate tumor cell invasion. Finally, I will show examples of how the model can be used to model tumor growth and cell metastasis.
Video Archive
IMC Colloquium Series: "Seismic Inversion with Multiply-Scattered Waves"
Alison Malcolm
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology
Date: Jan 06, 2012
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Seismic images are typically made using the single scattering assumption, which linearizes the inverse problem. I will discuss extensions to two seismic imaging methods to include multiply scattered waves. These methods use a series approach to solve a sequence of linear inverse problems to iteratively include waves with more reflections and thus improve the illumination of the image.
Video Archive
IMC Open Forum: IRMACS 2011 Thematic Year Showcasing Scientific Modelling at SFU Wrap-up
Date: Dec 02, 2011
Time: 11:30 - 13:00
Room: ASB10900
Abstract
TBA
Video Archive
IMC Colloquium Series: " 'Lassoing' a tree: Phylogenetic theory for sparse patterns of taxon coverage"
Mike Steel
University of Canterbury, Christchurch, New Zealand
Date: Nov 23, 2011
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Phylogenomic data often exhibit partial taxon coverage, whereby each loci is present or sequenced only for some corresponding subset of the species under study. This leads to some interesting mathematical and statistical questions as to whether a fully resolved underlying evolutionary tree for all the taxa can be reconstructed, given perfect phylogenetic estimates from each locus. We first describe the extent to which a pattern of taxon coverage can be 'phylogenetically decisive' in various senses, and provide some applications to data (joint work with Sanderson and McMahon). We then consider tree reconstruction from distance data, in settings where accurate estimates of evolutionary distance exist between only certain pairs of taxa: Does this partial information suffice to pin down - or, as we say, 'lasso' - the underlying phylogenetic tree? We describe a number of new combinatorial results concerning lassos (joint work with Dress and Huber). We conclude with some open problems.
About the speaker: Mike Steel directs the Biomathematics Research Centre, and is Professor in the Mathematics and Statistics Department of University of Canterbury, Christchurch, New Zealand. He is the deputy director (2009-), and a founding principal investigator of the Allan Wilson Centre for Molecular Ecology and Evolution. He is also an elected fellow of the Royal Society of New Zealand, and is an Associate Editor (2009-) of IEEE/ACM Transactions in Computational Biology and Bioinformatics, and is on the editorial boards of Journal of Computational Biology and Evolutionary Bioinformatics.Video Archive
IMC Colloquium Series: "A Neutral Model of Gang Territory Formation"
Jeffrey Brantingham
Anthropology, UCLA
Date: Sep 23, 2011
Time: 11:00 - 12:00
Room: ASB10900
WebSite: Click Here
Abstract
Many criminal street gangs are territorial in nature claiming compact geographic regions as their home turf. Gangs defend their territories both with the threat and use of violence. A neutral model based on spatial Lotka-Volterra competition equations shows that territories are strictly stable only where gangs are exactly symmetrical in all characteristics, which we interpret as a neutral condition. We test the model against data on violent crime involving thirteen street gangs in a region of Los Angeles. We find excellent agreement between model predictions and the observed spatial distribution of crime.
Video Archive
IMC Colloquium Series: "University 2.0: Next Generation University to offer free, world-class education with global partners to democratize health sciences knowledge"
Kate Tairyan, MD, MPH
Faculty of Health Sciences, Simon Fraser University
Date: Sep 09, 2011
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
The world is ready for University 2.0. We have been delivering 1.0 - traditional university education - for over one thousand years now. However, we are clearly failing to meet the need for adequately trained health workers, as we are lacking four million health workers according to World Health Organization globally, and over one million in Africa alone. Dr. Kate Tairyan, MD, MPH, Senior Lecturer at the Faculty of Health Sciences will present her work on NextGenU - the world's first free university. She will outline the transformative model of delivering high quality education with competency-based online curriculum plus community-based mentored and peer-to-peer activities. She will present the "four freedoms" that this new model of University 2.0 includes: a world-class education that is free of cost, barriers, advertisements and carbon emissions. One of the first programs that NextGenU will offer is the world's first free public health degree, a goal to be accomplished with the help of her recent Rising Stars in Global Health award from Grand Challenges Canada. Opportunities for partnerships with NextGenU initiatives will be presented, and individuals and organizations interested in joining the pioneering venture will be welcomed.
Video Archive
IMC Colloquium Series: "Sources of bias for estimators of gene-by-environment interaction from case-parent trio data"
Brad McNeney
Department of Statistics and Actuarial Sciences, Simon Fraser University
Date: Apr 01, 2011
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
The case-parent trio design was popularized by the well-known transmission-disequilibrium test, which conditions on parental genotype information at a test locus to make inference about genetic association that is robust to population stratification. The TDT considers alleles transmitted to the affected offspring (case) as well as those not transmitted (pseudo-controls). The availability of pseudo-controls has lead to a popular belief that the case-parent design itself is robust to population stratification. While this may be true for tests of genetic main effects, some caution is required when extending to inference of gene-by-environment interaction. In this talk, we discuss examples of estimators of gene-by-environment interaction from case-parent trio data and scenarios under which they are biased because of population stratification.
This is joint work with J.-H. Shin and J. Graham.Video Archive
IMC Colloquium Series: "Are Stock Markets Beauty Contests?"
Kenneth Kasa
Department of Economics, Simon Fraser University
Date: Mar 18, 2011
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
In 1936, Keynes drew an analogy between investing in the stock market and predicting the winner of a beauty contest, where the winner is the contestant who is most often selected by others. Since everyone knows that everyone else is trying to predict average opinion, an infinite regress ensues. Keynes argued that markets are bound to be volatile when average opinion itself becomes the object of speculation.
Formalizing Keynes' metaphor has been difficult, as it leads to infinite dimensional fixed point problems. This talk will discuss how frequency domain methods can be used to solve these problems. Evidence is presented that higher-order belief dynamics play a significant role in observed asset markets.Video Archive
IMC Colloquium Series: "Modelling the Expansion of the Highly Active Anti-retroviral Therapy for HIV, within Risk Behaviour Environment"
Bojan Ramadanovic
Complex Systems Modelling Group, The IRMACS Centre, Simon Fraser University
Date: Mar 04, 2011
Time: 11:30 - 12:30
Room: ASB10900
Abstract
One of the key contributors to the spread of the HIV epidemic is the prevalence of risk behaviour, such as unprotected sexual contact and the sharing of infected hypodermic syringes, within the susceptible population. We assume that risk behaviour is a social phenomenon and that the propensity of any given individual to engage in such behaviour depends on the norms within their social environment. The likelihood of any given susceptible individual engaging in risky behaviour then becomes a function of the prevalence of risk behaviour in their immediate social group. In this view, behavioural interventions could target either the frequency and intensity of risk behaviour (harm reduction strategies) or the ability of those engaging in risk behaviour to recruit others (education and risk awareness campaigns).
Another important factor influencing HIV epidemics (particularly in rich countries) is the increased use of Highly Active Antiretroviral Therapy (HAART), which both prolongs the healthy life of the treated individual and dramatically reduces their infectiousness. Presence of HAART program can impact the risk-behavioural patterns in a variety of ways - not least by "normalizing" the risky behaviour by reducing apparent treat of HIV (in so-called "HAART optimism"). Our model studies the interplay between HAART and various behavioural interventions and their combined impact on the spread of HIV in the population.Video Archive
IMC Colloquium Series: "Modeling human expression and creativity using cognitive based artificial intelligence"
Steve DiPaola
School of Interactive Arts and Technology, Simon Fraser University
Date: Feb 11, 2011
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
By using parameterization techniques which model the knowledge space of a living or cognitive systems (eg. the behavior space of whales, the expression space of faces) it is possible to use Artificial Intelligence techniques such as Neural Networks and Genetic Programming to create new types of expression systems for use in communication, learning, interactive games and digital media systems. Steve DiPaola will discuss and demonstrate his work in this area (see ivizlab.sfu.ca). Best known for his expertise in AI based 3D facial and avatar systems, DiPaola will demonstrate iFace research which uses a parameterized approach to synthetic facial communication, and its applications in psychology, gaming and learning. He will show his lab's ongoing work with the Vancouver Aquarium to create an alife based Virtual Beluga Whale Interactive, where visitors can collaboratively interact with a simulated pod of wild beluga whales, as well as more experimental systems that explore expression and creativity models -- such as genetic programming techniques that create Persian rugs design and art paintings as a way to enhance automatic computer creativity.
About the speaker: Steve DiPaola, active as an artist and a scientist, is Director of the Cognitive Science Program at Simon Fraser University, and leads the iVizLab (ivizlab.sfu.ca), a research lab that strives to make computational systems bend more to the human experience by incorporating biological, cognitive and behavior knowledge models. Much of the labs work is creating computation models of very human ideals such as expression, emotion, behavior and creativity. He is most known for his AI based computational creativity (darwinsgaze.com) and 3D facial expression systems. He came to SFU from Stanford University and before that NYIT Computer Graphics Lab, an early pioneering lab in high-end graphics techniques. He has held leadership positions at Electronic Arts, Saatchi Innovation and consulted for HP, Macromedia and the Institute for the Future. His computer based art has been exhibited internationally including the AIR and Tibor de Nagy galleries in NYC, Tenderpixel Gallery in London and Cambridge University's Kings Art Centre. The work has also been exhibited in major museums, including the Whitney Museum, the MIT Museum, and the Smithsonian. His science work has been published in over 50 peer reviewed science publications and showcased in the journal Nature.Video Archive
IMC Colloquium Series: "Analyzing illegal drug supply chains as two-mode social networks"
Martin Bouchard
School of Criminology, Simon Fraser University
Date: Jan 21, 2011
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
A promising avenue for law enforcement agencies to have an impact on drug trafficking networks is to focus on the most important actor, the one that is least likely to be in abundant supply: the "key player". It is the one that, if removed, will produce the most destabilizing impact in a trafficking network. Identifying this key player is a challenge in itself. In this paper, the key player is defined as one of the many positions that illegal drug market participants may occupy, from importer to retailer. The individual drug trafficking networks of 187 incarcerated drug market participants active at different positions in are brought together in order to reconstitute the full drug supply chain. Drawing on two-mode social network analysis where the relations are defined between individuals and the positions with which they interact, we examine the relative power and centrality of 14 distinct positions in the chain. The findings show that the middle market distributors hold the most central position in the chain. Rarely the focus of empirical research or of police investigations, these distributors are the only ones having access to the full supply chain. The policy and research implications of these findings will be discussed.
Video Archive
IMC Colloquium Series: "Distributions matter: variability in the numbers and types of sexual partners of female sex workers and the HIV epidemic in south India"
Kathleen Deering
BC Centre for Excellence in HIV/AIDS
Date: Dec 03, 2010
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
The current study investigates the features of the population-level sexual structure of female sex workers (FSWs) in three districts in south India and their sexual partners, including distributions of FSWs' numbers of sexual partners and sexual partnership patterns. Using a deterministic mathematical modelling approach and empirical data, this study demonstrates how population-level sexual structure influences HIV prevalence, as well as the effectiveness of HIV prevention interventions among FSWs and their partners.
Video Archive
IMC Colloquium Series: "GeoSimulation Approach for Modeling Human Disease Dynamics"
Suzana Dragićević
Department of Geography, SFU
Date: Nov 19, 2010
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Human infectious diseases are emerging with increasing frequency and intensity. Some examples are recent outbreaks of H1N1 influenza, severe acute respiratory syndrome (SARS), measles, vector-borne malaria, avian flu or legionnaire's disease among others. These diseases impose serious concerns for public health professionals. The evolution of human infectious disease outbreaks depends on many factors such as population, their movements and interactions, transportation, water quality and availability, climate and land-use/land-cover change. The relationship among factors is often complex making it difficult to predict, localize and control the disease spread. Complex system theory and its application within a geospatial and temporal context provide an effective means to address and model some of these infectious diseases. A geosimulation approach for modeling the dynamics of a human infectious disease spread in an urban environment will be presented as a pilot study developed within the Spatial Analysis and Modeling (SAM) Lab of the Geography Department, SFU.
About the speaker: Dr. Suzana Dragićević is a Professor at the Department of Geography and director of the Spatial Analysis and Modeling (SAM) Research Laboratory at SFU. Her research program is related to the integration of complexity theory, geographic information systems (GIS) and soft computing for multi-scale spatial modeling and decision-making. Applications areas include land-use/land-cover change, urban growth, geography, forestry, landscape ecology and epidemiology. She has published over 60 peer-reviewed papers and book chapters, conference papers, book reviews and a co-edited book. Dr. Dragićević has served on many local and international conference program committees, is a co-editor of the Springer book series on ``Advances in Geographic Information Science"; editor for GIScience, The Canadian Geographer journal; associate editor for Modeling and Decisions Support Systems, Geomatica journal; and a member of the editorial boards for several international journals.Video Archive
IMC Colloquium Series: "Reclamation: Experiments in Homelessness and Crime"
Julian Somers
Faculty of Health Sciences, SFU
Date: Nov 05, 2010
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
The most precious and powerful resources of any society are its' peoples. The social exclusion of large numbers of citizens creates unsustainable costs and simultaneously threatens the integrity and security of society. This talk focuses on recent initiatives designed to reduce social exclusion among identified sub-populations: the homeless; drug addicted offenders; and those who commit a high number of crimes in their communities. Current projects in British Columbia highlight innovative experiments in public policy, and incorporate a variety of empirical methods, including randomized controlled trials and population-evel data linkages. These ongoing studies are producing new insights into the characteristics and needs of marginalized members of society. This research is also developing new knowledge concerning the effectiveness of public initiatives that are intended to reduce the human and financial costs associated with social exclusion.
About the speaker: Dr. Julian Somers is an Associate Professor in SFU's Faculty of Health Sciences. His research focuses on the integration of services and information in order to reduce substance use problems and improve mental health in the population. Julian (MSc, PhD, RPsych) completed his doctorate under G. Alan Marlatt in the area of addictions, and has collaborated extensively with branches of government on initiatives involving substance use and mental health. He has led Provincial and multi-jurisdictional projects in the areas of telehealth, primary healthcare reform, housing, and the corrections system. Dr. Somers has held a number of academic and professional leadership positions, including Director of the UBC Psychology Clinic, President of the BC Psychological Association, and Director of the Centre for Applied Research in Mental Health and Addiction.Video Archive
IMC Colloquium Series: "Cellular Automata, a tool in pure and applied mathematics"
Vahid Dabbaghian
The MoCSSy Program, The IRMACS Centre, SFU
Date: Oct 22, 2010
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
A cellular automata (CA) is a discrete mathematical model of spatial interactions of particular states, which changes stepwise according to specific rules conditioned on the states of neighboring cells. CA model has several applications in mathematics, physics, theoretical biology and microstructure modelling. In this talk we first review its recent application for modeling complex social systems such as, modeling HIV spread through sexual contact, modeling residential migration in response to neighborhood social dynamics, and modeling crime and the impact of liquor licensed establishment density. Then we show how linear cellular automata yields interesting patterns on elements of permutation groups, when elements are ordered by lexicographic ordering.
Video Archive
IMC Colloquium Series: "The Risky Business of Modeling Impacts of Climate Change on Groundwater Systems"
Diana M. Allen
Department of Earth Sciences, SFU
Date: Sep 24, 2010
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Groundwater constitutes the main potable water supply source for human consumption and irrigation of agriculture worldwide. Groundwater also sustains streams, lakes and wetlands during baseflow periods and supports aquatic habitat. Climate change is anticipated to result in impacts on hydrological systems, including groundwater systems; however, determining the range of possible impacts can be quite challenging. In this presentation, basic hydrogeological concepts are introduced to provide context for understanding the complex dynamics of groundwater systems in mountain regions. For climate change impacts assessment, the challenges arising from downscaling, recharge modeling, groundwater-surface water interactions, and global climate model uncertainty, along with the associated risks for groundwater management, are discussed using examples from two case study areas in British Columbia. Some thoughts on risk assessment approaches are offered as a means to manage groundwater given the degree of uncertainty in climate change predictions.
Video Archive
IMC Colloquium Special Presentation: "Statistical Modeling of Complex Agroecosystems in a Changing Climate"
Nathaniel K. Newlands
Research Scientist, Agriculture and Agri-Food Canada, Research Centre, Lethbridge, Alberta
Adjunct Professor, Department of Statistics , University of British Columbia
Date: Sep 21, 2010
Time: 13:30 - 14:30
Room: ASB10900
Abstract
Natural resource problems typically must be modeled using data that is often incomplete, asynchronous and collected at different spatial and temporal scales with differing levels of measurement uncertainty. Both deterministic and stochastic models are widely applied in assessing environmental impacts, identifying risks and informing resource management decision-making for agricultural systems. However, existing models are high-dimensional, requiring extensive site-specific calibration, thereby limiting their spatial application. Likewise, simpler models, inevitably, must be combined to aid in more robust, integrative regional management or national policy-relevant decision-support. Using variable- and model-selection statistical techniques, one can identify models of intermediate complexity that can achieve appreciable reductions in parameter and structural uncertainty. In this way, such models may offer more reliable support to address a range of applications/problems and to identify critical thresholds and allocation trade-offs. My talk will discuss several collaborative, inter-disciplinary projects that are investigating ways to improve the prediction and forecasting of crop production for food and energy in relation to water-use efficiency and climate variability across Canada. I will highlight the use of wireless sensor monitoring network and satellite remote-sensing data. The talk will also showcase several national-scale, web-based decision-support systems currently in development. Here, the ability to refine and adapt models to take into account spatial and temporal-type operational constraints is of vital importance.
About the speaker: Dr. Nathaniel Newlands is a Research Scientist in Agriculture and Agri-Food Canada and an Adjunct Professor in the Department of Statistics at the University of British Columbia, Vancouver, Canada. He is an active member of the International Association of Ecology and the International Environmetrics Society. He completed a Honours B.Sc. in Physics and Mathematics (Univ. of Guelph), a M.Sc. in Astrophysics (Univ. of Calgary), and Ph.D. in Environmental Modeling (Univ. British Columbia). He is a participating member of the Agro-climate Research Board within the Canadian Program for Complex Data Structures, and a coordinating partner in the development of an operational regional crop yield forecasting system being by the Canadian Agroclimate Information Service.IMC Colloquium Series: "Jump Detection with Wavelets for High-Frequency Financial Time Series"
Ramazan Gençay
Department Of Economics, Simon Fraser University
Date: Apr 16, 2010
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
This paper introduces a new nonparametric test based on wavelets to detect jump arrival times in high frequency financial time series data. The asymptotic distribution of the test is derived. We demonstrate that the test is robust for different specifications of price processes and the presence of the microstructure noise. A Monte Carlo simulation is conducted to show that the test has good power and size. Further, we examine the multi-scale jump dynamics in U.S. equity markets. The main findings are as follows. First, the jump dynamics of equities are entirely different across different time scales, suggesting that choosing a proper sampling frequency is important to extract full jump dynamics. Second, although arrival densities of positive jumps and negative jumps are symmetric across different time scales, the magnitude of jumps is distributed asymmetrically at high frequencies. Third, only twenty percent of jumps occur in the trading session from 9:30AM to 4:00PM, suggesting that jumps are largely determined by news rather than liquidity shocks.
Video Archive
IMC Colloquium Series: "Modeling to Estimate Weight Gain from Energy Imbalances"
Diane Finegood and Penny Deck
Department of Biomedical Physiology and Kinesiology, Simon Fraser University
Date: Mar 19, 2010
Time: 10:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Several model based approaches have been used to estimate the energy imbalance that accounts for population weight gain in recent decades. These estimates suggest that differences of as little as 50 to 100 calories excess energy intake over expenditure accounts for the rising prevalence of obesity. These estimates have led to the suggestion that small decreases in energy balance should accordingly result in weight loss. We will explore this concept and what population level and individual level models suggest are appropriate strategies to reverse the epidemic of obesity.
Video Archive
IMC Colloquium Series: "From the Unbounded to the (Artificially) Bounded"
Nilima Nigam
SFU Department of Mathematics
Date: Mar 05, 2010
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
The study of wave interactions with obstacles has a rich mathematical history. Interesting and challenging issues arise when we numerically simulate these phenomena. For example, we can only discretize a bounded region, so one method is to introduce an artificial surface enclosing the obstacle. Instead of allowing waves to scatter off bounded obstacles in free space, we now have to study their action inside this computational box. What effect does the truncation have on the original model problem, which is posed in all of space? What further effects do discretization errors bring? We quickly survey some techniques for describing the so-called non-reflecting boundary conditions, and present some new work on the construction of exact Dirichlet-to-Neumann maps. Along the way, we need tools from functional analysis, PDE theory, numerical analysis and asymptotics.
IMC Colloquium Series: "Geographic Injury Surveillance"
Nadine Schuurman
Department of Geography, Simon Fraser University
Date: Feb 05, 2010
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Each year, 5 million people die from injuries sustained from road traffic collisions, as a result of falls, on the, job, or due to violence. Another 100 million people are severely injured or permanently disabled by these mechanisms. Together, these events, which are often preventable, are a leading cause of potential years of life lost, lost productivity, and inestimable hardships for individuals, families and society. In British Columbia, more than 400,000 are injured each year. Of these, 26,000 require hospitalization, over 9,000 are left with permanent disabilities, and 1600 die, resulting in the loss of over 37,000 potential years of life. In Canada and around the world, injury is increasingly recognized as an important public health issue requiring investment in research, thoughtful analysis and vigorous action. A public health approach - based on identifying and reducing risk - to injury control is considered to be most effective method of reducing the burden of injury. This talk focuses on way that geographic information science, spatial analysis and cartography can be used to identify clusters of injury, correlates with socio-economic status, impediments to access, as well as the role of enhanced data collection in resource poor environments. The role of GIS in understanding and mitigating injury will be illustrated by reviewing multiple injury surveillance projects in British Columbia, Canada and South Africa.
Video Archive
IMC Colloquium Series: "Engineering Security: A Formal Approach"
Uwe Glasser
SFU IRMACS Centre and School of Computing Science
Date: Jan 22, 2010
Time: 12:30 - 13:30
Room: ASB10900
WebSite: Click Here
Abstract
Security builds on abstractions that call for accurate models to be analyzed and validated so as to ensure they serve their purpose. Abstract operational security requirements can naturally be described in terms of discrete mathematics and computational logic. Mathematical precision is essential for reasoning about critical properties and to uncover and eliminate design flaws and weaknesses that often go unnoticed otherwise; it is also a prerequisite for using computational methods and tools, for instance, in experimental studies by means of computer simulation as a feasible alternative to performing real world experiments. We illustrate the approach by presenting our experience with various collaborative R&D projects, with government agencies and industrial partners, on computational criminology, decision support for coastal surveillance, identity management, and situation analysis.
Video Archive
IMC Colloquium Series: "A Particle Filter Approach to Identification of Discrete Stochastic Nonlinear Processes Under Missing Observations"
Bhushan Gopaluni
Department Of Chemical & Biological Engineering, University Of British Columbia
Date: Nov 27, 2009
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
A novel maximum likelihood solution to the problem of identifying parameters of a nonlinear model under missing observations will be presented. If the observations are missing, then it is difficult to build a partial likelihood function consisting of only the available observations. Hence, a variant of expectation maximization (EM) algorithm, which uses the expected value of the complete log-likelihood function including the missing observations, is developed. The expected value of the complete log-likelihood (E-step) in the EM algorithm is approximated using particle filters and smoothers. New expressions for particle filters and smoothers under missing observations are derived. In order to reduce the variance on the smoothed states, a point-wise (as opposed to path- based) state estimation procedure is used. The maximization step (M-step) in the EM algorithm is performed using standard optimization routines. The proposed nonlinear identification approach is illustrated through numerical and industrial examples.
Video Archive
IMC Colloquium Series: "Measuring Social Influences on Health"
Brian Krauth
Department of Economics, SFU
Date: Nov 13, 2009
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Conventional wisdom and substantial evidence suggest that a person's social environment affects both health behavior and health outcomes. However, obtaining credible measurements of these effects runs into the problem that social environment is at least partly chosen. As a result, the set of likely omitted/confounding variables is virtually unlimited. My talk will describe a research program that aims to quantify the uncertainty associated with effect measurements in this context. The unifying idea is to characterize the importance of omitted variables relative to included control variables. I will also describe applications to the measurement of peer effects in youth smoking, and of the effect of income inequality on health.
Video Archive
IMC Colloquium Series: "Recent Advances in Medical Imaging"
Joe Qranfal
Department of Mathematics, SFU
Date: Oct 30, 2009
Time: 11:30 - 12:30
Room: ASB10900
Abstract
Images and visualization have become increasingly important in many areas of science and technology. Advances in hardware and software have allowed computerized image processing to become a standard tool in many scientific applications, including medical imaging. In this talk, we see how we model and solve the inverse problem of reconstructing a dynamic medical image where the signal strength changes substantially over the time required for data acquisition. We use a stochastic approach based on a Markov process to model the problem. We introduce a novel proximal approach and apply it during the Kalman filter algorithm to ensure positivity and spatial regularization. We test our method for the case of image reconstruction in time-dependent single photon emission computed tomography (SPECT). Numerical results corroborate the effectiveness of our approach.
Video Archive
IMC Colloquium Series: "Simple questions with difficult answers: Modelling the HIV epidemic in BC"
Robert Hogg
Faculty of Health Sciences, SFU
Date: Oct 16, 2009
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
TBA
Video Archive
IMC Colloquium Series: "The Arithmetic of Sentencing"
Pierre Tremblay
School of Criminology, University Of Montreal
Date: Oct 02, 2009
Time: 11:30 - 12:30
Room: ASB10900
Abstract
I will talk about scaling of severity of various penalties (fine, probation, prison)our ability to establish reasonable severity equivalencies. The main subject matter of the talk will be to ask if lawyers and judges have a more cogent understand of penal metrics than the general public.
Video Archive
IMC Colloquium Series: "Systems Thinking for Health Systems Renewal"
Allan Best
Centre for Clinical Epidemiology and Evaluation, Vancouver General Hospital
Date: Sep 18, 2009
Time: 11:30 - 12:30
Room: ASB10900
WebSite: Click Here
Abstract
Health policy and health organisation leaders are emphasizing the importance of evidence when searching for new ways to tackle complex public health issues (such as obesity and health inequalities) and address enduring organisational challenges (such as safety, efficiency and patient-centredness). Yet, how we think about the challenge of moving from evidence to policy, or from evidence to organisational change, profoundly shapes the ways we work and the results that we get. Today, our ways of thinking are changing fundamentally, as we come to understand that our health systems are complex systems, demanding fresh conceptual models, more integrative research methodology, and organizational forms that nurture and support evidence-informed decision making. We need more interdisciplinarity, more systems thinking, more problem-based research, and some serious restructuring of the ways in which universities, research funders, and health service organizations are designed. If this systemic change is stifled, we risk never realizing our potential for creating and using knowledge in a collaborative way, and we commit an injustice to the populations we serve. Imagine a system in which researchers, decision makers and practitioners work collaboratively throughout the full knowledge creation, synthesis, and application process. Think about how tenure and promotion policies might change if contributions to social good were valued as much as contributions to knowledge. Reflect on how knowledge from randomization and experimental control might be balanced by real-world data and learning from practice. Ask what it will take to develop new analytic methods that capture the dynamic, multilevel nature of change as health systems work to continuously improve.
