VictorJuiz/thesis huggingface dataset:
Mixing time for the Ising model and random walks

In this thesis we study the mixing times of Markov chains, e.g., the/nrate of convergence of Markov chains to stationary measures. We/nfocus on Glauber dynamics for the (classical) Ising model as well as/nrandom walks on random graphs./nWe first provide a complete picture for the evolution of the mixing/ntimes and spectral gaps for the mean-field Ising model. In/nparticular, we pin down the scaling window, and prove a cutoff/nphenomenon at high temperatures, as well as confirm the power law at/ncriticality. We then move to the critical Ising model at Bethe/nlattice (regular trees), where the criticality corresponds to the/nreconstruction threshold. We establish that the mixing time and the/nspectral gap are polynomial in the surface area, which is the height/nof the tree in this special case. Afterwards, we show that the/nmixing time of Glauber dynamics for the (ferromagnetic) Ising model/non an arbitrary $n$-vertex graph at any temperature has a lower/nbound of $n \log n/4$, confirming a folklore theorem in the special/ncase of Ising model./nIn the second part, we study the random walk on the largest/ncomponent of the near-supcritical Erd\"os-R\'{e}nyi graph. Using a/ncomplete characterization of the structure for the/nnear-supercritical random graph, as well as various techniques to/nbound the mixing times in terms of spectral profile, we obtain the/ncorrect order for the mixing time in this regime, which demonstrates/na smooth interpolation between the critical and the supercritical/nregime.

Advisor: Peres, Yuval
Mossel, Elchanan
Encounters at tamál-húye: An Archaeology of Intercultural Engagement in Sixteenth-Century Northern California

This dissertation explores an intercultural engagement and its material aftermath, as well as larger processes of culture change and continuity in sixteenth-century northern California. The starting points for the research are cross-cultural encounters between Tamal hunter-gatherers and English voyagers under Sir Francis Drake in 1579 and the Spanish crew from the shipwrecked Manila galleon San Agustín in 1595, which occurred in tamál-húye, the Coast Miwok-language name for present-day Drakes Bay, California. Archaeological evidence from extensive excavations around tamál-húye during the 1940s-1970s indicates that Tamal villagers took advantage of the body of introduced material culture from the San Agustín shipwreck by salvaging objects and incorporating them into their cultural practices. I utilize this body of existing archaeological data, and a historical anthropological approach incorporating multiple lines of evidence, to address two primary questions about the cross-cultural encounters at tamál-húye that have not been addressed in detail by previous researchers./nFirst, I evaluate how the Tamal people incorporated material culture from the shipwreck into their cultural practices by analyzing museum collections, archival excavation records and original field notes, and published reports from the earlier investigations, and by incorporating additional data from ethnography, historical documents, and native oral traditions. I recreate the excavations in a Geographic Information System (GIS) to analyze intra-site artifact and feature patterning, and I examine the correlation between distributions of sixteenth-century introduced objects and indigenously-manufactured items. Second, using a framework based on an "event-oriented" archaeology, I assess whether this short-term, pre-colonial event, and the material culture introduced as a result, was a source of long-term Tamal culture change. I investigate whether Tamal salvage and reuse of the ship's cargo, and incorporation of the introduced material culture into their daily lives, resulted in transformations to Tamal cultural practices./nMy results suggest the Tamal people incorporated material culture from the San Agustin shipwreck in complex ways. Some porcelain fragments were modified into traditional artifacts such as bead blanks, pendants, bifaces, and other objects, while the large quantity of unmodified porcelain fragments may represent discarded by-products from the production of these and other objects. Overall, the ways in which the Tamal recontextualized sixteenth-century introduced objects were a complex combination of utilitarian and symbolic reuse.

Advisor: Lightfoot, Kent G.
Simulating the Effect of Microclimate on Human Behavior in Small Urban Spaces

This dissertation describes a behavior simulation model which could reveal spatial usage pattern of small urban places in association with the tangible physical built environment and the intangible microclimatic conditions. The simulation model extends the existing environmental assessments which do not include human interactions and human behavior simulations which do not take into account microclimatic conditions. It addresses the problem of predicting and evaluating the impacts of microclimatic conditions on the spatial usage of its human inhabitants, which has been studied, but not successfully implemented in the past./nThe concept is to carry out a virtual post occupancy evaluation which virtual users would exhibit their spatial usage pattern according to the environmental conditions and physical environment so experienced. Evaluators then could see how virtual users perform under certain conditions and assess if the design intention is achieved./nThe simulation model is developed using Wei Yan's (Yan, 2005) urban simulation model as a base. In addition Yan's usability-based building model and agent-based behavior model, an environmental model is included. It manages environmental data from user input, database and other simulation programs. It records the shading and air speed profile onto the building model to affect individual user behavior, develops outdoor activity comfort maps which virtual users would use to develop activity option maps, and control collective usage pattern in terms of level of usage, activity type distribution and spatial distribution./nTo ensure quality results, the environmental model handles only relatively simple computation, like generating outdoor activity comfort maps. It does not handle assessments which require specialized algorithms and processes like air flow simulation and comfort evaluation. Rather, these assessments are handled by certified programs outside the system. The environmental model processes the result and distributes the information to the building model and the agent model to control the behavior of the virtual users at both collective and individual levels./nAt the collective level, the behavioral pattern is mainly governed by statistics obtained from a year round field study. At individual level, the behavior is based on well studied and defined behavioral rules which are derived from theoretical and practical environment-behavior studies./nThe simulation generates both graphical and textual outputs. The two dimensional graphical output offers views of paths of virtual users; the three dimensional output offers shows spatial usage as a whole; and textual output provide information of usage and thermal states./nIt is expected the result of this research to change how architects and environmental behavior experts will approach the design and evaluation of built environments.

Advisor: Kalay, Yehuda E
Rhodium Catalyzed C-H Bond Functionalization: Development of Methods and Applications in Organic Synthesis

Chapter 1. A sequence of research projects beginning with studies in diastereoselective C-H bond functionalization applied to the synthesis of (-)-incarvaillateine to the Rh(III) catalyzed arylation of imines, are described. Some theory and mechanistic considerations are discussed in relation to the genesis of these projects. Research directions are summarized and rationalized./nChapter 2. The synthesis of (-)-incarvillateine utilizing a key C-H bond alkylation step is described as a means to highlight the synthetic utility of a newly reported olefinic C-H bond functionalization methodology. Elements of diastereoselectivity are also explored in the key step which allows for the concise, stereoselective synthesis of the natural product. Progress in the area of enantioselective C-H alkylations are also summarized as it applies to the synthesis of other natural products./n/nChapter 3. A method for the enantioselective cyclization of N-allylimidazoles is developed. The reaction is thought to proceed via a novel, reactive N-heterocyclic carbene. High enantioselectivities are achieved, which is unusual in view of the elevated temperatures of the reaction./nChapter 4. The first general method for the oxidative coupling of unactivated alkenes via C-H bond functionalization is reported using a methyl oxime directing group. A silver abstractor is important to obtain reactivity. Several functional groups are compatible with the reaction and no precautions to exclude air are required./nChapter 5. A rare example of C-H activation and intermolecular coupling to N-protected-imines is achieved using a cationic Rh(III) catalyst. The reaction is directed by pyridines and related heterocycles and produces a variety of aryl-branched amines. The reaction accommodates several reactive functional groups and is mild enough to even couple with sensitive alkyl N-sulfonyl-imines.

Advisor: Bergman, Robert G
Changing the State's Story: Continuity and Change in Official Narratives of Dark Pasts

This theory-building dissertation investigates how states' narratives about dark pasts are shaped and contested over time, employing macro-historical analysis to trace the trajectories over the past several decades of Turkey's narrative of the Armenian Genocide and Japan's narrative of the Nanjing Massacre./nIn a time of unprecedented access to information and increased scrutiny of how the past is represented, how are some states able to maintain national narratives that are at odds with widely accepted versions of the underlying historical events? Why do some states attempt to come to terms with the past perpetration of genocide or mass killing, while others deny wrongdoing for decades? Despite dramatic increases in truth-telling, truth-seeking and state apologies for historic wrongs, there remains both a great deal of variation in how states deal with their own dark pasts and insufficient understanding of the sources of this variation. Given that narratives about past atrocities can increase threat perception between states, can be used by leaders to justify war to domestic audiences, and can create tensions and prejudices that contribute to future conflicts, there are compelling reasons to investigate the dynamics underlying this variation./nThe core question answered in this dissertation is: What are the sources of change and continuity in states' narratives of past crimes? Existing research tells us that domestic regime change, transnational activism and shifts in international alliances can bring about changes in states' narratives of dark pasts. Offering an integrating framework that incorporates the domestic and international spheres, I argue that while international pressures can increase the likelihood of change in official narratives of dark pasts, domestic actors largely determine the content of such change. Moreover, in contrast to observers who have warned that progressive changes in states' narratives threaten a backlash from the right, I argue that actors across the political spectrum contest and shape narratives of the past. My findings are based on more than eight months of fieldwork, including archival research in Turkey, and over seventy-five elite interviews conducted in Turkey, Japan and the United States./nBuilding on comparative research on institutional change and feedback effects, this research contributes to literature on the impact of international norms, institutions and law on states' behavior, to scholarship on the politics of memory and transitional justice, and to work at the intersection of Turkish studies and genocide studies. My research will also help policymakers better deal with controversies over the past, by revealing the sources of change and continuity in narratives of the past and the longer-term dynamics set off by pressures on and changes in official narratives.

Advisor: Hassner, Ron E.
Silverstein, Gordon
TRISO Fuel Performance: Modeling, Integration into Mainstream Design Studies, and Application to a Thorium-fueled Fusion-Fission Hybrid Blanket

This study focused on creating a new tristructural isotropic (TRISO) coated particle fuel performance model and demonstrating the integration of this model into an existing system of neutronics and heat transfer codes, creating a user-friendly option for including fuel performance analysis within system design optimization and system-level trade-off studies. The end product enables both a deeper understanding and better overall system performance of nuclear energy systems limited or greatly impacted by TRISO fuel performance. A thorium-fueled hybrid fusion-fission Laser Inertial Fusion Energy (LIFE) blanket design was used for illustrating the application of this new capability and demonstrated both the importance of integrating fuel performance calculations into mainstream design studies and the impact that this new integrated analysis had on system-level design decisions./nA new TRISO fuel performance model named TRIUNE was developed and verified and validated during this work with a novel methodology established for simulating the actual lifetime of a TRISO particle during repeated passes through a pebble bed. In addition, integrated self-consistent calculations were performed for neutronics depletion analysis, heat transfer calculations, and then fuel performance modeling for a full parametric study that encompassed over 80 different design options that went through all three phases of analysis. Lastly, side studies were performed that included a comparison of thorium and depleted uranium (DU) LIFE blankets as well as some uncertainty quantification work to help guide future experimental work by assessing what material properties in TRISO fuel performance modeling are most in need of improvement./nA recommended thorium-fueled hybrid LIFE engine design was identified with an initial fuel load of 20MT of thorium, 15% TRISO packing within the graphite fuel pebbles, and a 20cm neutron multiplier layer with beryllium pebbles in flibe molten salt coolant. It operated at a system power level of 2000 MWth, took about 3.5 years to reach full plateau power, and was capable of an End of Plateau burnup of 38.7 %FIMA if considering just the neutronic constraints in the system design; however, fuel performance constraints led to a maximum credible burnup of 12.1 %FIMA due to a combination of internal gas pressure and irradiation effects on the TRISO materials (especially PyC) leading to SiC pressure vessel failures. The optimal neutron spectrum for the thorium-fueled blanket options evaluated seemed to favor a hard spectrum (low but non-zero neutron multiplier thicknesses and high TRISO packing fractions) in terms of neutronic performance but the fuel performance constraints demonstrated that a significantly softer spectrum would be needed to decrease the rate of accumulation of fast neutron fluence in order to improve the maximum credible burnup the system could achieve.

Advisor: Greenspan, Ehud
Investigating the Role of Lipid Anchors in Live Cell Membrane Organization Using Fluorescence Fluctuation Spectroscopy

The cellular plasma membrane is a heterogeneous and dynamic two-dimensional fluid. It has long been considered the necessary boundary between the internal components of a cell and the surrounding environment. The organization of membrane proteins, originally thought to freely and randomly diffuse throughout the plasma membrane, has been recognized as essential to the proper functioning of a cell. Evidence from detergent extraction of membranes, model membranes, and nanometer resolution microscopy techniques requiring cell fixation have supported the idea that the membrane, through lipid-lipid and lipid-protein interactions, plays an active role in membrane protein organization. Advanced fluorescence microscopy and spectroscopy techniques offering subdiffraction resolution have added to the evidence and knowledge of heterogeneity in the membrane lipid bilayer of live cells, but have led to mixed results on the exact role that lipid-lipid and lipid-protein interactions play in lateral membrane organization./nHere we employ pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS) to study the co-diffusion of lipid anchors in live cell membranes. Lipid anchors are lipid moieties often found attached to membrane proteins. They function to tether proteins to membranes, and we ask if they also play a larger role in lateral membrane organization. We use fusions of fluorescent proteins and lipid anchors that participate in only lipid-lipid and lipid-peptide interactions without any direct protein-protein interactions. PIE-FCCS allows us to observe the co-diffusion of two different colored species while completely removing cross-talk due to spectral bleed-through and simultaneously measuring the fluorescence lifetimes to monitor energy transfer. We find a highly specific organizing scheme wherein different anchors partition into distinct domains, and we see no evidence of Förster resonance energy transfer through fluorescence lifetimes indicating the absence of tight anchor interactions.

Advisor: Groves, Jay T
Citizenship Begins at Home: How Families Shape Immigrant Incorporation

German citizenship law was reformed in the year 2000 in an attempt to incorporate millions of long-term foreign residents. Yet rather than increasing, the numbers applying for German citizenship have been falling ever since the reform. This dissertation offers an explanation of this puzzling development. In so doing it suggests a new answer to the question of why some foreign residents take the citizenship of their country of residence, while others do not./nI argue that the decision to apply for citizenship is typically made along with other family members. In many cases, applying for citizenship together with others in the family allows the benefits of acquiring citizenship to be multiplied and the costs to be split. The benefits of citizenship include increased security, the right to political participation, easier travel and full access to the labor market. Foreign residents place greater value on many of these benefits if they are shared with others in the family. Parents are especially likely to apply if they can thereby acquire citizenship for their children. The financial, cognitive and social costs of changing citizenship can also be reduced by spreading them across the family./nAlthough the German reform of 2000 eased key criteria for becoming a citizen, it decreased the numbers applying together with other family members. The country introduced birthright citizenship for children whose parents had lived in the country for a number of years, but this has the effect of removing a key reason for many parents to apply for citizenship. The reform of 2000 also brought new tests of individual integration, especially language skills. The focus on the individual is having perverse collective effects. Although most foreign residents satisfy the criteria, many live with someone who doesn't, and the prospect of leaving this person out can discourage the entire family from applying./nThe evidence for the argument advanced in this dissertation is drawn from over 100 in-depth interviews as well as statistical analysis of census data. The dissertation makes a novel methodological contribution by using information on other household members to study the dynamics of the decision over citizenship. This reveals not only that citizenship status is clustered by household, but also that people living together commonly apply for citizenship at the same time.

Advisor: Lee, Taeku
Levy, Jonah
Interdomain Multipath Routing

While astonishingly successful, Internet is still less reliable than the phone system and supports very limited user choice and control. As many researchers observed, multipath routing is a promising paradigm to address these issues. In this thesis, we argue that multipath routing can indeed go a long way towards these goals as well as lead to a more scalable, extensible, and evolvable Internet./nWe begin by describing Yet Another Multipath Routing (YAMR) protocol that provably constructs a set of paths resilient to any one interdomain link failure. YAMR uses an efficient scheme to construct the paths and a novel failure hiding technique to further reduce the control plane overhead./nNext, we describe Pathlet Routing, a protocol that departs from the path-vector paradigm. Pathlet routing allows ASes to advertise policy-compliant path segments called pathlets, and allows users to stitch them together, thus forming a complete path suitable for the user's particular needs. Pathlet routing greatly reduces the forwarding table size, can efficiently express a wide class of routing policies, and provide an exponential number of paths to the users. Finally, we investigate how pathlet routing can be a basis for an evolvable Internet architecture.

Advisor: Shenker, Scott
Making Race in the New South: Mexican Migration and Race Relations in Winston-Salem, North Carolina

In this dissertation, I investigate how race is produced by looking at the reception experiences of Afro and Mestizo Mexican migrants to the New South. Despite the fact that Afro and Mestizo Mexicans are both phenotypically and culturally distinct from one another, they now assert a shared racial identity as minorities and as Latinos. Based on ethnographic field work in Winston-Salem, North Carolina, I argue that pervasive discrimination due to status drives Mexicans to assert a minority identity that is shaped by their understanding of African-American experiences, and that Mexicans as a whole in this context find themselves increasingly distanced from whites./nThe literature on intergroup relations argues that racial and ethnic relations, particularly between minority groups, are rife with conflict and competition. Moreover, the immigration literature suggests that relations with African-Americans are particularly poor in part because upward mobility is achieved by avoiding associations with Blacks, and aspiring toward whiteness. However, in the case of contemporary Mexican migrants in Winston-Salem, I find the opposite processes emerging. Rather than a sense of closeness with whites, Mexicans express a sense of closeness with Blacks, increasingly viewing themselves as minorities and as similar to Blacks. I describe these positive interminority relations as emerging in three ways- through contact and social closeness; solidarity and a sense of shared discrimination; and an emerging sense of linked fate. Using a 12-month ethnographic case study of Winston-Salem, I seek to explain this counterintuitive outcome. My study shows that these positive relations are facilitated by their sense of shared status with African-Americans, an absence of resource competition, sustained positive contact with Blacks, and identifying a common enemy in whites. The implications of these findings for other U.S. communities are considered.

Advisor: Smith, Sandra S