Nigel D. Goldenfeld - US grants

Research will be conducted on mesoscopic descriptions of non- equilibrium phenomena associated with materials science. Models of non-equilibrium systems will be studied in terms of discrete space- time maps, which permit efficient computational tools to be developed. Using this approach dynamical scaling properties will be studied using both numerical and analytical techniques, including renormalization group techniques. Specific systems to be studied within the scope of the grant include: spinodal decomposition of polymeric systems, including hydrodynamics; dynamics of crystal surface reorganization; the effect of coexisting phase ordering on spinodal decomposition; polymer crystal growth; dynamical scaling at the onset of gelation; and, vulcanization.

9970690
Goldenfeld
This is an award for a theoretical investigation of a wide variety of systems of relevance to materials research. The research impacts systems far from equilibrium, biological materials, pattern formation processes during phase transitions, and aspects of high temperature superconductivity. In addition, there is special emphasis on the development of analytic renormalization group methods and novel simulation tools to bridge the gap between microscopic physics and macroscopic behavior. This project advances current understanding in the areas of materials processing and the behavior of complicated materials, and the methodology is broadly applicable to systems with a complex interplay of length- and time-scales. By working at the intersection of materials science, theoretical physics and applied mathematics, students and postdocs associated with this research receive a unique training in the applications of renormalization group theory and the development of novel computational algorithms.

This is an award for a theoretical investigation of a wide variety of systems of relevance to materials research. The research impacts systems far from equilibrium, biological materials, pattern formation processes during phase transitions, and aspects of high temperature superconductivity. In addition, there is special emphasis on the development of analytic renormalization group methods and novel simulation tools to bridge the gap between microscopic physics and macroscopic behavior. This project advances current understanding in the areas of materials processing and the behavior of complicated materials, and the methodology is broadly applicable to systems with a complex interplay of length- and time-scales. By working at the intersection of materials science, theoretical physics and applied mathematics, students and postdocs associated with this research receive a unique training in the applications of renormalization group theory and the development of novel computational algorithms.
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ABSTRACT

Objectives and Methods: The goal of this proposal is to determine how the biodiversity and activity of specific living microbes and/or microbial communities are required to create the terraced architectures universally observed in high-temperature and low-temperature carbonate spring deposits. Results will provide a fundamental knowledge of microbe-water-mineral interactions during carbonate precipitation that are needed to more accurately reconstruct the history of microbial life on earth and other planets. This project advances the field of biocomplexity by combining geological studies, microbial rDNA and gene analyses and quantitative modeling to provide a detailed geobiological account of carbonate terrace formation. The integrated multidisciplinary research and educational aspects of this project meet a national need to train personnel for future geobiology and biocomplexity studies.

The project is headed by a unique interdisciplinary research team with specific expertise in geology, microbiology, and physics. Project milestones include:1) performing in situ crystallization experiments to determine the form and chemistry of travertine deposited when the microbes have been UV-irradiated, a sterilization technique that will leave the other fundamental physical and chemical conditions of the spring drainage outflow relatively unchanged; 2) documenting associations between calcite crystal growth form, distribution and chemistry with microbial form, diversity and metabolic activity; and 3)quantitative modeling of carbonate terrace formation using stochastic differential equations to describe the combined effects of geological and biological processes.

Mammoth Hot Springs is the most appropriate natural laboratory in the world for conducting the proposed research. Although CO2 degassing and decreasing temperatures strongly influence the spring water chemistry, significant biological controls on travertine crystal form and isotope chemistry have recently been quantitatively documented.
Mammoth Hot Springs uniquely offers:1) precipitation rates as high as 5 mm/day that allow short-duration in situ crystallization experiments in a regime of coupled biological and physical influences;2) the full spectrum of high-to low-temperature carbonate precipitates at one site;3) long-term familiarity of the study site by the PI 's who have all required research permits in hand; and 4)the only easily accessible hot spring complex in the world protected in its natural state.

Intellectual Merit: The main question addressed is whether the presence of terraced carbonate architecture is prima facie evidence for the presence of microbial activity. Results from this study will permit the identification of microbiologically influenced crystallization in other modern and ancient high-temperature and low-temperature terraced carbonate spring deposits. The techniques employed in the quantitative modeling provide a first principles understanding of significant geological features from a physical and biological perspective. Of equal importance, the results from this study will establish a systematic and quantitative toolkit to identify microbial influence during carbonate deposition that can be used in a wide variety of other important terrestrial, marine, and burial environments on earth and other planets.
Broader Impacts: This systems-level understanding of the interaction between biological and geological processes and resultant conceptual approaches will provide learning opportunities at all levels from postgraduate to K-12, as well as to the general public. The program to train personnel in biocomplexity studies will include undergraduates, graduate students, and postdocs, international student exchange with the University of Siena in Italy, web-based curriculum development for Geobiology courses, and the development of a formal Geobiology program at Illinois. This project enhances public awareness of the need for biocomplexity studies through museum displays, brochures, and interpretive trail signs for the Canyon and Mammoth Hot Springs Visitor Centers in Yellowstone National Park, which will be seen and used by over 3 million park visitors each year.

Non-technical
Consider a turbulent fluid such as oil pumped through a pipeline with a rough interior wall, a river flowing between its irregular banks, or a weather front crossing mountainous terrain. For economic reasons, for storm prediction, and for public safety it is important to understand how turbulent friction converts some of the flow energy into heat. This project is aimed at understanding this phenomenon. Turbulence is also a fertile ground of understanding chaotic behavior. The laws of chaos govern fluctuations in fluid flow, stock market gyrations, and irregularities of the heart and the brain. In one set of proposed experiments, chaos and disorder are investigated in turbulent flows. The project has a strong educational element. A sizeable group of undergraduates receive lectures in fluid dynamics as they work in the laboratory during the summer. It has also proved possible to introduce ideas of chaos into the Pittsburgh school system.

Technical
Fluid flowing through smooth or roughened pipes exert stress on the on the wall. The resulting frictional loss is a non-monotonic function of the Reynolds number (Re) and the pipe roughness. Drawing on ideas from critical phenomena and scaling, Nigel Goldenfeld has shown that all known measurements can be mapped into a single curve. Goldenfeld's approach will be put to an experimental test for a two-dimensional system, namely the flow of a soap film between two parallel, roughened vertical wires. Measurements are also made of the motion of particles that float on a strongly turbulent tank of water. These floaters sample the underlying flow at the surface. One can relate the velocity divergence of the floaters to the entropy S, or rather its rate dS/dt. This rate is a random variable and not identically zero as in the bulk. The results will be compared with computer simulations and with the "fluctuation theorem", which is an extension of the fluctuation-dissipation theorem, applicable only to systems near thermal equilibrium. The experiments provide a good training ground for both undergraduates and graduate students.

NON-TECHNICAL ABSTRACT: Turbulent flows past a wall experience frictional drag, the property of a flow that sets the cost of pumping oil through a pipeline, the draining capacity of a river in flood, and other quantities of practical interest. Much is known about the frictional drag, mostly from extensive experiments in which the frictional drag was measured in pipes or open channels, yet, there has been no known link between the frictional drag and the statistics of the turbulent eddies in the flow. The project' goal is to test experimentally a recently proposed theory that will allow us to predict the frictional drag from a knowledge of the statistics of the turbulent eddies. This will be achieved through measurements in a type of two-dimensional turbulent flow that may be realized in very thin soap films, where it is possible to create flows with different types of statistics. If confirmed, the theory could provide the key to understanding the drag-altering effects of polymeric additives used in oil pipelines, particulate suspensions found in rivers in flood, entrained bubbles found in water-treatment plants, and other agents known to affect the statistics of the flow. At Illinois and Pittsburgh, graduate and undergraduate students will be trained with a multidisciplinary focus encompassing engineering and fundamental condensed matter physics, introducing undergraduates and women to research in turbulence. The PIs will collaborate on outreach to grades 6-12, work with an all-girl's middle school to devise a unit on soap film physics, turbulence, chaos and optics, and participate in a teacher's workshop.

TECHNICAL ABSTRACT: Turbulent flows past a wall experience frictional drag, the property of a flow that sets the cost of pumping oil through a pipeline, the draining capacity of a river in flood, and other quantities of practical interest. While much is known about the frictional drag, there has been no known link between the frictional drag and the turbulent spectrum (i.e., the statistics of turbulent fluctuations in the flow). The goal of this project is to test experimentally a recently proposed theory that would provide the missing "spectral link". If confirmed, the theory could prove key to understanding the drag-altering effects of polymeric additives used in oil pipelines, particulate suspensions found in rivers in flood, entrained bubbles found in water-treatment plants, and other agents known to affect the spectrum. The theory has been tested in two-dimensional soap-film turbulent flows with the type of spectrum known as the enstrophy cascade, but so far it has not been possible to create similar flows with the type of spectrum known as the inverse energy cascade. A method to create soap-film flows with the inverse energy cascade will be developed; it will then be used to measure the frictional drag of inverse cascade dominated 2D turbulence, completing the experimental verification of the spectral link. At Illinois and Pittsburgh, the PIs will train graduate and undergraduate students with a multidisciplinary focus encompassing engineering and fundamental condensed matter physics, introducing undergraduates and women to research in turbulence. The PIs will collaborate on outreach to grades 6-12, working with an all-girl's middle school to devise a unit on soap film physics, turbulence, chaos and optics, and participating in a teacher's workshop.

? DESCRIPTION (provided by applicant): Social experiences impact nearly every facet of human behavior, and social adversity can have devastating and long-lasting health effects on mental and emotional health. A comprehensive framework of how social interactions are processed at the molecular, individual behavioral and societal levels is thus essential to fully understand both healthy and impaired social behavior. Plasticity in transcriptional regulatory networks plays a crucial and deeply conserved role in body plan development, and we hypothesize that it also underlies social behavior (another highly plastic property of an organism's biology). To test this hypothesis, we will use an established model of social behavior (the honey bee) to explore the bidirectional flow of information between three levels of biological organization: 1) brain neurogenomic state, 2) individual behavior, and 3) emergent properties of the society. Aim 1 will examine reciprocal feedback between behavioral state and the regulatory functions of two transcription factors (TFs) predicted in previous systems biology studies to play prominent roles in brain gene expression networks regulating social behavior. RNA interference will be used to knock down expression of these TFs and neuroendocrine-mediated manipulation of behavioral state, and to thereby test the hypothesis that social behavior is controlled by context-dependent rewiring of brain transcriptional regulatory networks. Aim 2 will use a novel technology to automatically monitor the social interactions of every bee in the colony, in order to characterize how alterations in the neurogenomic and behavioral state of a set of focal bees (as done in Aim 1) influence the social interactions and brain gene expression of untreated individuals. Aim 3 will then generate novel algorithms to describe the emergent properties of the social network as a whole, and use them to construct a simulation of how the proportion of individuals in a particular behavioral or neurogenomic state influences the global properties of the social network. These analyses will allow us to identify mechanisms of information flow from the transcriptome to the social network, as well as determine how a social network responds to changes in social group composition. The outcome of this research will be a multi-level model of the reciprocal relationships between brain transcriptional regulatory networks, individual behavior, and societal function. This model will provide new insights into how genes influence social behavior and how an individual's neurogenomic and behavioral states influence social groups, with important implications for our understanding of how healthy and pathological behavior influence societal function.

Group testing is a screening technique that relies on careful combinatorial mixing and testing of batches of samples. By using group testing instead of individual testing, for most problem settings of practical interest, one is guaranteed significant savings in the number of tests performed and consequently, significant reductions in reporting delays and experimental costs. Group testing is especially desirable when monitoring the spread of infectious diseases such as Covid-19, which requires frequent examinations of massive populations. Although many ad-hoc approaches to group testing for infectious diseases have been put forward, little work has addressed the problem of end-to-end group-testing protocol design, which includes the selection of genetic regions for viral/bacterial identification, mathematical modeling and analysis of the test results and the development of guiding protocols for communal testing strategies. The overarching goals of the project are to determine which group-testing methods can actually mitigate the spread of Covid-19 and other diseases and to what extent, to estimate the reduction in the number of infected individuals achievable through the use of pooled real-time polymerase chain reaction (RT-PCR) tests, and to aid in the employment of Mobile Testing Units that can reach geographically remote regions. Other broader societal impacts include increased readiness for fighting future pandemics and training a new cohort of young researchers on interdisciplinary topics involving machine learning, coding theory and bioinformatics.

The project aims to develop specialized machine-learning, combinatorial and information-theoretic methods for (a) identifying genomic regions with predictably low-mutation rates that may be used as amplification primers for gold-standard real-time polymerase chain reactions (RT-PCR) and determining best mixing strategies based on the likelihood of infection; (b) developing adequate models for amplification curves generated by RT-PCR and corresponding test-errors; (c) formulating experimental-protocol-specific non-adaptive and adaptive semiquantitative group testing schemes that account for nonbinary test outcomes; (d) addressing the testing issues associated with high-viral load subjects and heavy-hitter communities; and (e) integrating the mathematical techniques developed into an agent-based model for disease spreading and control in order to assess the potential impact of group testing and recommend effective test-quarantine-retest strategies.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.