Talk Abstract. Where do rebel organizations successfully control territory during insurgency? Under what conditions does community-level collective action influence rebel territorial control? Existing theories of rebel control have emphasized geography, natural resources and identity- or ideology-based affinity within the population, with mixed empirical support. This paper emphasizes non-combatants' political role in conflict processes: it argues that community collective action capacity, the ease with which communities facilitate collective action to pursue common interests, influences the distribution of territorial control during civil war. Communities with high collective action capacity deter rebels by raising the costs of controlling territory. Under certain conditions, collective action capacity also increased the expected benefits to rebels associated with controlling territory; in particular, where rebels seek population-dependent resources such as intelligence regarding counterinsurgent strategy, food/supplies, population concealment, or political legitimacy. I test the theory within a single case: the communist insurgency in the Philippines. I fit a linear multilevel model, regressing Armed Forces of the Philippines measures of village-level rebel influence on collective action capacity measured by summarizing village family network structure using data from a 2008-2010 Poverty Census. The results suggest the social structure in conflict-affected communities predict the level of rebel influence, consistent with the theory.
Are the ice sheets collapsing? (Quantitative Climate Change Series)
Talk Abstract. Human civilization has developed during a period of relatively stable sea level, preceded by rapid pulses of rising oceans during deglaciation. Will our warming atmosphere and oceans bring a return to the catastrophic conditions of the early Holocene, or worse? The concept that ice sheets can change substantially on timescales of centuries or less is new, and the past decade has brought radical changes in our understanding of their dynamics and how they react to changes at their air and ocean boundaries. Yet, our understanding is far from complete and predictions are still highly uncertain: current estimates of sea level rise for this century range from decimeters to over a meter. Starting from a basic global energy and mass balance perspective, we will review the mechanisms driving ice sheet response to climate and assess the potential for rapid, near-future sea level rise.
Evolutionary Population Dynamics (Quantitative Biology & Theoretical Biophysics Series)
Talk Abstract Why does evolution continually produce and maintain so much diversity? While a long standing puzzle for multicellular organisms, this is even more striking for bacteria which appear to exhibit diversity at every scale probed. This talk illustrated aspects of bacterial diversity from deep DNA sequencing in the laboratory and of natural populations, then explored potential steps towards understanding via crude abstract models of evolutionary dynamics that caricature the complexities of organisms, environments, and their interactions.
Expanding Governance as Development: Evidence on Child Nutrition in the Philippines (Special Lecture Series)
Tuesday Apr 5, 2016
Eli Berman, Department of Economics, University of California: San Diego
Talk Abstract.Worldwide, extreme poverty is often concentrated in spaces where people and property are not safe enough to sustain effective markets, and where development assistance is dangerous –and might even induce violence. Expanding governance by coercively taking control of territory may enable markets and development programs, but costs to local residents may exceed benefits, especially if that expansion is violent. We estimate for the first time whether a large counterinsurgency program improves welfare. We exploit the staggered roll-out of the Philippine “Peace and Development Teams” counterinsurgency program, which treated 12% of the population between 2002 and 2010. Though treatment temporarily increased violence, the program progressively reduced child malnutrition: by 10% in the first year, and by 30% from year three onwards. Improved nutritional status was not due to increased health and welfare expenditures, but instead to improved governance. Treatment effects are comparable to those of conventional child health interventions, though conventional programs are likely infeasible in this setting. Rebels apparently react to treatment by shifting to neighboring municipalities, as malnutrition worsens there –with statistically significant ‘treatment’ effects of similar size. Thus overall program effects are close to zero. These findings invite an evidence-based discussion of governance expansion, an extensive margin of development.
Parsimony and Chimpanzee Mind-reading (Visiting Fellows Speaker Series)
Talk Abstract. Are chimpanzees mind-readers? That is, besides forming beliefs about the physical objects in their environment, do they also form beliefs about the mental states of other chimpanzees? Psychologists have tried to answer this question by using Ockham's razor. In fact, two sorts of parsimony have been invoked -- phylogenetic parsimony and blackbox parsimony. Although it is generally conceded that phylogenetic parsimony is on the side of the mind-reading hypothesis, it is controversial what conclusion can be drawn from that fact. With respect to blackbox parsimony, some psychologists have argued that this consideration counts in favor of the mind-reading hypothesis while others contend that parsimony counts against the hypothesis. In my talk, I'll try to clarify both sorts of parsimony arguments.
The Hippocampus: from Memory into Space and Back (Quantitative Biology & Theoretical Biophysics Series)
Talk AbstractIn this seminar, the speaker contrasts the spatial and memory narratives that have dominated these last few decades of hippocampal research, leading to the somersault caused by the discovery of grid cells. Besides yielding a Nobel prize for Edvard and May-Brit Moser, grid cells have paradoxically refocused attention on the dentate gyrus, as one of two key innovations introduced in the mammalian nervous system some 250 million years ago.
Talk Abstract. Many scientists believe that the search for simple theories is not optional; rather, it is a requirement of the scientific enterprise. When theories get too complex, scientists reach for Ockham’s razor, the principle of parsimony, to do the trimming. This principle says that a theory that postulates fewer entities, processes, or causes is better than a theory that postulates more, so long as the simpler theory is compatible with what we observe. Ockham’s razor presents a puzzle. It is obvious that simple theories may be beautiful and easy to remember and understand. The hard problem is to explain why the fact that one theory is simpler than another tells you anything about the way the world is. In my lecture, I’ll describe two solutions.
Models for melt drainage in ice sheet dynamics (Quantitative Climate Change Series)
Talk Abstract. This lecture begins with a brief introduction to basic ice sheet dynamics, focusing on a handful of processes that play a dominant role in determining steady state configurations of a simplified ice sheet and their stability. Recent developments in modelling subglacial drainage will then be discussed including, our current understanding about how water drains along glacier beds us based on ideas that were mostly developed in the 1970s and 1980s, and how we have only recently succeeded in drawing these ideas together in spatially extended two-dimensional models. Reviewed will be the basic physics involved, and show how this dictates the rich dynamical structure of the model - where we have a channelizing instability that differs from that for hillslope stream formation, and the possiblity of oscillatory behaviour in the form of subglacial outburst floods. Much of the talk will be motivated by the application of drainage models to seasonal variations in ice flow in Greenland, where time-varying water supply causes summer-time speed- ups and slow-downs in ice flow by changing the lubrication of the glacier bed.
The stabilized supralinear network: A simple "balanced network mechanism explaining nonlinear cortical integration (Quantitative Biology & Theoretical Biophysics Series)
Wednesday Mar 2, 2016
Ken Miller, Departments of Neuroscience and Physiology & Cellular Biophysics at Columbia University
Talk Abstract. This talk will include key aspects of (i) the science of climate change, (ii) why international agreement on climate change policy has proven particularly difficult, and (iii) what the Paris agreement on climate change is achieving and could achieve in the future. Manmade greenhouse gases are slowly forcing the climate system to change. Carbon dioxide emissions from fossil fuel burning are the dominant cause of climate change. Some of today's carbon emissions will still affect the atmosphere in a thousand years and beyond, leading to a very long 'commitment' to future climate change. Increases in carbon dioxide arise from a mix of different countries,both developed and developing, with different current emissions, infrastructure capabilities, and past commitments, and these human factors shape global policy discussions. Comparisons will be briefly drawn between the success of policy on ozone depletion (Montreal Protocol) and the prospects for success of the Paris agreement, adopted by nearly 200 countries in December, 2015.
Do human fertility declines result from stopping or slowing? A novel mixture model for estimating two pathways to the fertility transition. (Special Lecture Series)
Wednesday Feb 17, 2016
Daniel Hruschka, School of Human Evolution & Social Change, Arizona State University
This workshop is designed to provide attendees with a basic introduction to text analysis — computational techniques for studying the content of text — for social science applications. It will feature applications to social media analysis (Twitter). No prior experience working with text data is needed. Basic knowledge of R is helpful but not required. The workshop will include three mini-units: (1) collecting and structuring raw text for analysis; (2) cleaning and manipulating text to prepare it for analysis; and (3) describing and analyzing text for social science applications. The workshop was sponsored by QTM. Led by Joshua Fjelstul
Earth System Stability through Geologic Time (Quantitative Climate Change Series)
Talk Abstract. The five great mass extinctions of the last 500 million years are each associated with significant perturbations of Earth's carbon cycle. But there are also many such environmental events not associated with mass extinction. What makes them different? We show that natural perturbations of the carbon cycle exhibit a critical rate of change resulting from a transient balance between the photosynthetic uptake and respiratory return of CO2. The critical rate is also the fastest rate at which the resulting excess CO2 can be produced in a sustained steady state. We identify the critical rate with marginal stability, and find that four of the five great mass extinctions occur on the fast, unstable side of the stability boundary. Moreover, many severe yet relatively benign events occur close to the boundary. These results suggest that major environmental change is characterized by common mechanisms of Earth-system instability. The most rapid instabilities result in mass extinction.
Data Visualizations: Drawing Actionable Insights from Data (Annual Theme Series)
Talk Abstract. In an age of information overload, the ability to make sense of vast amounts of data and to render insightful visualizations is as important as the ability to read and write. This talk explains and exemplifies the power of visualizations not only to help locate us in physical space but also to help us understand the extent and structure of our collective knowledge, to identify bursts of activity, pathways of ideas, and borders that beg to be crossed. It introduces a theoretical visualization framework meant to empower anyone to systematically render data into insights together with tools that support temporal, geospatial, topical, and network analyses and visualizations. Materials from the Information Visualization MOOC and maps from the Places & Spaces: Mapping Science exhibit will be used to illustrate key concepts and to inspire participants to visualize their very own data.
Emerging hierarchies in biological distribution networks (Quantitative Biology & Theoretical Biophysics Series)
Talk Abstract. Biological transport webs, such as the blood circulatory system in the brain and other animal organs, or the slime mold Physarum polycephalum, are frequently dominated by dense sets of nested cycles. The architecture of these networks, as defined by the topology and edge weights, determines how efficiently the networks perform their function. In this talk we present some general models regarding the emergence and extraction of hierarchical nestedness in biological transport networks. In particular, we discuss how a hierarchically organized vascular system is optimal under conditions of variable, time-dependent flow, but also how it emerges naturally from a set of simple local feedback rules. To characterize the topology of these weighted cycle-rich network architectures, we develop an algorithmic framework that analyzes how the cycles are nested. Finally, using this algorithmic framework and an extensive dataset of more than 180 leaves and leaflets, we show how the hierarchical organization of the nested architecture is in fact a distinct phenotypic trait, akin to a fingerprint, that characterizes the vascular systems of plants and can be used to assist species identification from leaf fragments.
Near Miss: The Importance of the natural atmospheric CO2 concentration to human historical evolution (Quantitative Climate Change Series)
Talk Abstract. When fossil fuel energy was discovered, the timing and intensity of the resulting climate impacts depended on what the natural CO2 concentration in the atmosphere was at that time. The natural CO2 concentration is thought to be controlled by complex, slow-acting natural feedback mechanisms, and could easily have been different than it turned out to be. If the natural concentration had been a factor of two or more lower, the climate impacts of fossil fuel CO2 release would have occurred about 50 or more years sooner, making it much more challenging for the developing human society to scientifically understand the phenomenon of anthropogenic climate change in time to prevent it.
The learnability of critical distributions (Quantitative Biology & Theoretical Biophysics Series)
Talk Abstract.Many biological systems, including some neural population codes, have been shown empirically to sit near a critical point. While many detailed discussions about the origins of these phenomena have been had in recent years, less is known about the utility of such behavior for the biological system. Here we demonstrate a potentially useful feature of such codes. We construct networks of interacting binary neurons with random, sparse interactions (i.e. an Erdos-Renyi graph) of uniform strength. We then characterize the discriminability of those interactions from samples by performing a direct coupling analysis and thresholding the direct information between each pair of neurons to predict the presence or absence of an interaction. By sweeping through threshold values, we compute the area under the ROC curve as a measure of discriminability of the interactions. We show that this resulting discriminability is maximized when the original distribution is at its critical point. This behavior may be useful for efficient communication between brain areas.
Public Lecture Series: Digital Mapping and the Humanities (QTM-Sponsored Series)
Throughout Spring 2016
According to the Digital Mapping & the Humanities webpage, Digital mapping "offers scholars fresh tools to develop research questions, analyze data, and publish findings. [...] [H]umanists at the forefront of this innovative approach to the study of art and history employ maps to provide refreshed looks at photography, soundscapes, cities, and developments in the art market. Cutting-edge projects featured in the series offer the Emory community and people across Atlanta an opportunity to consider a variety of approaches to the joining of geo-spatial analysis and humanistic inquiry." This series was co-sponsored by QTM.
The Institute for Quantitative Theory and Methods (QTM), Department of Economics, and Department of Health Policy and Management hosted the 2015 Georgia Health Economics Research Day. The purpose of the conference was to promote active discussion and exchange of current research in health economics and health policy, with a focus on researchers in the Atlanta area and surrounding academic communities.
Workshop: Atlanta Computational Social Science Workshop (QTM Sponsored)
Friday Dec 4, 2015
As computing grows ever more embedded into daily life, computational techniques can now be applied to shed insight on basic social science questions. At the same time, the increasingly social aspect of computing means that technologists must wrestle with and understand social science principles. The emerging cross-disciplinary field of computational social science addresses these challenges and opportunities, combining computational methods with social science theory and research. Georgia State University hosted the third annual workshop for exchanging research ideas in this growing research area. The workshop was sponsored in part by QTM.
Talk Abstract.Recognition of pathogens relies on the diversity of immune receptor proteins. Recent experiments that sequence the entire immune cell repertoires provide a new opportunity for quantitative insight into naturally occurring diversity and how it is generated. I will describe how we can use statistical inference to quantify the origins of diversity in these sequence and characterize selection in the somatic evolutionary process that leads to the observed receptor diversity. A well-adapted repertoire should be tuned to the pathogenic environment to reduce the cost of infections. I will finish by discussing the form of the optimal repertoire that minimizes the cost of infections contracted from a given distribution of pathogens.
Historical data visualization and presenting rich data archives (Annual Theme Series)
Talk Abstract.In the contemporary humanities, datasets are not just evidence but archives, demanding reinterpretation; visualization provides one of the richest and most widespread ways facilitating this. This talk will describe the reception and remarkable misrepresentations of the most influential single data visualization in the historical profession, the US Census's maps of the frontier line from the late 19th century; and then describe an agenda of web-based data visualizations using D3 geared towards exploratory analysis that can allow freer exploration of data archives as evidence. These platforms-for exploring census data, historical shipping routes, and text collections with metadata-embody an approach towards humanities data visualization not simply as presenting single views, but as creating weak domain-specific-languages for sharing data archives with scholars and a wider public.
Similarity Matching: A New Principle of Neural Computation (Quantitative Biology & Theoretical Biophysics Series)
Talk Abstract. Inspired by experimental neuroscience results we developed a family of online algorithms that reduce dimensionality, cluster and discover features in streaming data. The novelty of our approach is in starting with similarity matching objective functions used offline in Multidimensional Scaling and Symmetric Nonnegative Matrix Factorization. During this seminar, I discuss how we derived online distributed algorithms that can be implemented by biological neural networks resembling brain circuits. I will also cover how such algorithms may also be used for Big Data applications.
Catching Bad Guys with Visualization and Data Mining (Annual Theme Series)
Talk Abstract.Big data has redefined crime. We now see new breeds of crime where technologically savvy criminals cover their tracks with the large amount of data generated, and obfuscate law enforcement with multiple fake virtual identities. I will describe major data mining and visualization projects from my group that combat malicious behaviors by untangling sophisticated schemes crafted by criminals. 1) The Polonium malware detection technology that unearth malware from 37 billion machine-file relationships. Deployed by Symantec, Polonium protects 120 million machines worldwide. Our next generation Aesop technology pushes the detection rate to over 99%. 2) The NetProbe system detects auction fraud on eBay and fingers bad guys by identifying their networks of suspicious transactions. 3) Mixed-initiative graph sensemaking, such as the Apolo system and the MAGE system that combines machine inference and visualization to guide the user to interactively explore large graphs.
QSS Major Event: Networking Night 2015
Thursday Oct 8, 2015
QTM & the Career Services office put on a great event in the Fall for students to hear directly from the experts how quantitative training is changing their field. Students had an opportunity to chat with guests from academia, business, the non-profit sector and government during our 2015 Networking Night.
Clifford Carrubba (Professor, Department of Political Science and Institute for Quantitative Theory & Methods, Emory University)
Speaker: Nicole Miller (Manager, Quantitative Economics & Statistics (QUEST), Ernst & Young)
L-3 Data Tactics
Speaker: Nathan Danneman (Data Scientist, L-3 Data Tactics, Federal Contractor)
Excellence in Education
Speaker: Dana Rickman (Policy & Research Director, GA Partnership for Excellence in Education, Non-profit)
Biostatistics & Bioinformatics
Speaker:Howard Chang (Assistant Professor, Department of Biostatistics & Bioinformatics, Emory University)
Q & A Session
Panelists:Nicole Miller, Nathan Danneman, Howard Chang, Dana Rickman
The Value of Visualization for Exploring and Understanding Data (Annual Theme Series)
Talk Abstract. Investigators have an ever-growing suite of tools available for analyzing and understanding data. While techniques such as statistical analysis, machine learning, and data mining all have value, visualization provides an additional unique set of beneficial capabilities. In this talk I identify the particular advantages that visualization brings to data analysis beyond other techniques, and I describe the situations in which it can be most beneficial. Additionally, I identify three key tenets for success in data visualization: understanding purpose, embracing interaction, and identifying value. To help support these arguments, I will draw upon and illustrate a number of current research projects from my lab. One particular system demonstrates how visualization can facilitate exploration and knowledge acquisition from a collection of thousands of narrative text documents.
Emergent Physical Phenomena: from Biomolecules to Living Cells (Quantitative Biology & Theoretical Biophysics Series)
Talk Abstract. The internal microenvironment of a cell comprises an intricate choreography of molecules that must be transported from one location to another, elastic forces that must be overcome or harnessed into useful work, and molecular interactions whose rates must be carefully controlled. Using multi-scale models grounded in statistical physics and continuum mechanics, we study how collective physical phenomena arise from biomolecular constituents and how they impact biological function. From individual DNA-protein interactions to dynamic whole-cell deformations, this talk highlighted the importance of large-scale physical phenomena in the structure and function of living cells.
Legislative Effectiveness in the United States Congress (Special Lecture Series)
Talk Abstract. Starting with the premise that some members of Congress are more effective as lawmakers than are others, we develop Legislative Effectiveness Scores for each member of the U.S. House from the early 1970s through the present. We explore how this measure, and the study of effective lawmaking more generally, sheds new light on the most important topics of legislative politics, including: how parties influence legislative policymaking, the strategies that women and African Americans adopt in Congress to promote their policy goals, and how entrepreneurial lawmakers can develop issue expertise to overcome party polarization and policy gridlock. We also focus attention on the twenty most effective representatives of the past 40 years, and identify a collection of strategies and habits that legislators can use to become effective lawmakers.
Learning About the Vocal World: Deciphering the Statistics of Communication
Wednesday May 20, 2015
This interdisciplinary symposium brought together Emory faculty and internationally-recognized scholars from around the country, spanning fields as diverse as psychology, neuroscience, physics, and medicine, to share how they are using computational and quantitative methods to study the production and perception of vocal communication signals. The event was sponsored by Emory Conference Subvention Fund, the Institute for Quantitative Theory and Methods, the Center for Mind, Brain and Culture.