John P. Crimaldi - US grants

Engineering - Civil (54)

The project implements a sophisticated research technique, Planar Laser-Induced Florescence (PLIF), into a safe, versatile, and robust instructional tool at the University of Colorado. It adapts research and instructional implementations at Stanford University. The PLIF system is being incorporated into a dedicated teaching flume that students are using to visualize fluid flow and the effect of various interactions on the flow pattern. Five faculty members are incorporating the facility into their courses. Assessment tools include student surveys, open-ended interviews, written test, and course evaluations. The group is preparing a web site, a workshop, and engineering education publications describing the construction and implementation details along with assessment results.

This collaborative proposal describes research that links stream hydrodynamics, turbulent transport of odor signals, and the sensory ecology and behavior of the crayfish Orconectes rusticus. Crayfish use water-borne chemical signals ("odor plumes") as navigational cues for locating food, burrows, or mates, and for avoiding predators. The nature of the spatial and temporal variability ("structure") of the odor plumes depends on the hydrodynamic conditions, which, in turn, depends on the physical characteristics of the stream. The goal of the proposed research is to understand how crayfish use odor plumes to locate underwater objects. In particular, we plan to investigate how the crayfish navigational behavior varies under different hydrodynamic conditions (associated with different types of stream substrate materials). By focusing our attention to the changes in odorant structure and associated orientation behavior over different substrate types, we hope to gain insight into the specific algorithms and information cues used by the animals.

Ultimately, the knowledge gained from the proposed study could be used to design robotic vehicles to search for dangerous underwater objects, or to protect crayfish habitat in managed ecosystems. Environmentally, crayfish are keystone species for many stream habitats and understanding the physical, biological, and chemical factors that influence their behavior will lead to a broader understanding of stream ecology and the human impact on stream ecology. In particular, detailed knowledge of how stream habitats influence the distribution of chemicals will provide the information necessary to understand not only crayfish and stream ecology, but will help elucidate the physical mechanisms behind pollution transportation in streams and their possible impact on stream ecosystems.

The work outlined in this proposal is a collaborative effort between a biologist and engineer that will lead to cross-disciplinary training of both graduate and undergraduate students. In addition, new technical advances will be achieved through the development of high-speed and fine-scale three-dimensional measurements of chemical concentrations in different natural flow regimes. The development and quantification of these techniques will benefit a wide array of fields from oceanography to environmental engineering.

Discipline: Engineering-Other (59)

This project involves the development of a laminar flow facility to enhance conceptual understanding in the undergraduate fluid mechanics curriculum at the University of Colorado. The facility includes a laser-based flow visualization system, enabling students to directly visualize basic and complex flow phenomena that are typically difficult to observe. The flow facility and the visualization system are being adapted from facilities and techniques that were piloted as educational tools at Stanford University. Existing facilities in the PI's teaching laboratory enable students to study turbulent flow; the new flow facility is designed to produce laminar and transitional flows. Students can visualize and quantify aspects of laminar and transitional jets, boundary layers, and flows past obstacles (including unsteady wakes). An Engineering Assessment Specialist at the University of Colorado is involved with an assessment of the effectiveness of the facility as a learning tool. Assessment tools include surveys, open-ended interviews, written tests, and course evaluations. The equipment developed with this grant is being used to develop multi-media educational content for National dissemination in two NSF-sponsored activities: the TeachEngineering digital library (intended for K-12 education) and the Multi-Media Fluid Mechanics CD-ROM series (intended for undergraduate education).

Crimaldi - 0348855: CAREER: The role of turbulence structure in broadcast spawning: Exploring physical-biological relationships through an integrated research and education program.
This CAREER program is a combined educational and research project that is anchored by the PIs training in fluid mechanics, but whose application extends into interdisciplinary studies of benthic ecology. Both the educational and research aspects of the project are based on a foundation of three unifying objectives: (1) the study of physical-biological interactions, (2) the development of an integrated teaching and research laboratory, and (3) the use of visual laboratory techniques to promote learning and knowledge. The objective is to investigate how turbulence impacts the success of an external fertilization strategy commonly used by benthic invertebrates, while simultaneously promoting an approach to teaching fluid mechanics that emphasizes physical-biological relationships and makes use of visual-based research techniques as learning tools.
Many benthic invertebrates reproduce by separately extruding gametes into the flow. For fertilization to take place, individual gametes must subsequently come into contact. The local fertilization rate depends on the product of co-occurring gamete concentrations. Conventional thought has been that, since turbulence rapidly dilutes the concentrations, it might ultimately hinder fertilization. The central hypothesis in the proposed research is that turbulent stirring promotes local coalescence of gametes at intermediate timescales, thus enhancing fertilization rates. Several recent studies support this idea, but the problem has not been investigated from a process-level approach. To test the hypothesis, laboratory and numerical investigations will be performed. The laboratory experiments will utilize a state-of-the-art, dual-color laser-induced fluorescence technique to measure the instantaneous coalescence of gamete surrogates within a turbulent boundary layer in a flume. The numerical simulations will employ a particle-tracking algorithm to track several hundred thousand gametes through a pseudo-turbulent field. The two approaches are complimentary: the laboratory experiments use real turbulence, but the numerical simulations enable studies of the relative importance of various physical and biological processes not easily simulated in the flume experiments.
The research plan is in the context of a broader educational plan; the plans share concepts, infrastructure, and techniques. Extensive curriculum development will be performed, including the creation of three courses that constitute a new area of study in Environmental Fluid Mechanics, with an emphasis on dispersion processes in natural systems and physical-biological interactions. The curriculum development will be enhanced by dedicated teaching facilities in the proposed laboratory. A teaching flume that parallels the research facility will be incorporated as a central feature of undergraduate and graduate fluid mechanics courses. Finally, the laser-induced fluorescence flow visualization techniques that are used quantitatively in the research project will be adapted for both qualitative and quantitative use in the educational component. The visual techniques provide extraordinary insight into both basic fluid motion as well as the complex turbulent fluid processes that produce dispersion of contaminants (e.g. gametes, nutrients, toxins). The technique will be incorporated as an interactive feature on the teaching flume. The technique will also be used to produce studio-quality digital movies of fluid mechanics phenomena for inclusion in a NSF-sponsored Multi-Media Fluid Mechanics CD-ROM series (intended for undergraduate education), and the on-line TeachEngineering Digital Library (intended for K-12 education).
The foregoing activities will advance knowledge and understanding of fluid mechanics both within the field, and at interdisciplinary levels. Within fluid mechanics, the processes that govern stirring and mixing of multiple scalars are still poorly understood. The research will investigate stirring processes that are common to all turbulent flows. An understanding of the mixing and transport of contaminants is becoming a priority in a world that, increasingly, sees dispersive chemicals used as weapons. This program will have broad impacts through synergistic blending of sophisticated research techniques as effective visual learning tools, and a supportive combination of research and teaching facilities in an enhanced laboratory. The educational CD-ROM series and on-line Digital Library are both slated for national dissemination.
[edited 20 Jan 04, J. Pawlik]

The proposed research tests the hypothesis that sediment transport dynamics play a role in
controlling the topographic patterning that is crucial to the ecology of the ridge and slough landscape in
the Florida Everglades. Namely, under historical flow conditions, it is hypothesized that sediment
redistribution from open-water slough to vegetated ridge regulated ridge width but that, with drainage and
compartmentalization of the Everglades, the magnitude of redistribution has decreased, permitting
expansion of ridges into open-water sloughs and loss of topographic heterogeneity.
Project hypotheses will be tested through a combination of field and laboratory experimentation
and numerical modeling of the mass and momentum balance equations governing flocculent sediment
transport dynamics and flow in vegetated environments. Experimental analysis of floc transport
mechanics will describe the critical shear stresses and turbulence intensities that entrain size classes of
floc in a deposited bed, equilibrium aggregate size distributions and concentrations resulting from flow
with different shear parameters, aggregate settling velocities, and changes in turbulence and flow profiles
that occur across a ridge/slough cross-section as a result of vegetation and microtopography. To this end,
flow monitoring and a series of transport experiments and tracer tests using natural floc will be performed
in laboratory and field flumes. Funds will also sponsor the execution of complementary science fair
projects by Forest Hill High School environmental science magnet program students, which will focus on
using a rapid-assessment optical technique for developing an organic matter mixing model across a
ridge/slough transect (which can be used as a validation measure for the sediment transport model) and on
elucidating the effects of ambient water quality on flocculent organic sediment transport properties.
Intellectual merit. The proposed research builds upon previous research showing the existence of
sediment redistribution from open-water channels to vegetated environments by producing a model to
predict the magnitude and spatial distribution of sedimentation as a function of flow velocity and water
level. In the Everglades, sediment occurs primarily in the form of organic floccules, the mechanics of
which are not well understood. Similarly, although flocculation plays a dominant role in the suspended
sediment dynamics of rivers, wetlands, and estuaries throughout the world, studies on the impacts of flow
through vegetated environments on sedimentation and transport of floccules and predictive models of floc
dynamics on landscape morphology and evolution are nonexistent. This research develops a set of
laboratory and field experiments designed to address the critical questions about floc transport mechanics
required for model development and an original model of how these mechanics influence landscape
evolution. Thus, the proposed research will set a precedent for improved predictions of sediment
transport and landscape dynamics that will have implications for estuarine science, fluvial
geomorphology, wetlands science, and contaminant transport.
Broader impacts - Results of this project will be broadly disseminated to (1) researchers in the field,
through organization of a special session at an ASLO meeting on implications of flocculant sediment
transport for landscape dynamics and subsequent publication of a special journal issue, to (2) policy
makers involved in implementation of the Comprehensive Everglades Restoration Plan through regular
participation of the PIs in Landscape Subteam meetings and the Greater Everglades Ecosystem
Restoration conference, and to (3) the general public, through publication of a popular science article on
Everglades landscape dynamics. Further, model results will impact policy and society by leading to
improved recommendations of flow velocities and hydroperiods that should be implemented to restore the
ridge and slough landscape. Enhanced infrastructure resulting from the purchase of a laser diffraction
particle size analyzer will benefit classroom demonstrations, laboratory, and field research at the K-12,
undergraduate, and graduate levels. Research efforts will also enhance collaborative efforts between the
USGS, University of Colorado, and K-12 education and will synergistically complement an existing
USGS project on biogeochemical feedback mechanisms and nutrient transport within the ridge and slough
landscape. Finally, this research enhances the knowledge transfer to future generations of scientists
through a committed partnership with the environmental science magnet program at Forest Hill High
School in West Palm Beach, Florida and by providing research support to a current Ph.D student.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

The goal of this research is to determine the role of key biological and physical factors on fertilization rates in broadcast spawning, the reproductive strategy used by many benthic invertebrates. The objectives are to quantify the effect of gamete traits, instantaneous turbulence structure, and unsteady flow phenomena on subsequent gamete coalescence processes and fertilization rates. Fertilization is typically modeled as a bimolecular reaction, with the fertilization rate proportional to concentrations of gametes. Conventional thought has been that since turbulence produces efficient dilution of gamete concentrations, it hinders fertilization success. However, this conclusion is based on consideration of average turbulent dispersion. Recent work has provided evidence that instantaneous turbulence structure promotes local coalescence at shorter timescales, before dilution takes place, thus enhancing fertilization rates. This work will extend idealized numerical and laboratory studies to include ecologically relevant factors specific to the broadcast spawning process. It integrates numerical simulations and laboratory experiments to investigate process-level effects of individual biological and physical factors. The numerical simulations will consider the effects of gamete viscosity, rheology, and taxis, for 2D pseudo-turbulent flow, unsteady obstacle wakes, and 3D chaotic mixing scenarios. The laboratory experiments will model the effects of gamete viscosity, rheology, morphology, and buoyancy, using 3D boundary layer turbulence, obstacle wakes, and surface waves. A novel two-color planar laser-induced fluorescence system will be used to quantify concentrations of gamete surrogates, including those regions where they overlap. Surrogates made using dyed solutions of glycerol and a biopolymer will model the viscosity and rheology of sea urchin gametes, and fluorescent particles will be used to investigate size and inertial effects. Floating particles will be used to study the effect of convergence zones in free-surface turbulence on fertilization rates for species with buoyant gametes.

The educational and outreach goals are to integrate research methods into the PI's teaching curriculum as an effective tool for learning fluid mechanics, and to use the topic of broadcast spawning to get K-16 students interested in engineering and science. A numerical simulation platform will be integrated into a course; students will use the simulation environment and their knowledge of the Navier-Stokes equation to model an unsteady cylinder wake. Likewise, a simplified version of the obstacle wake experiment will be developed as a teaching tool. The PI will also develop an interactive laboratory demonstration to use with visiting groups. The demonstration will include a removable benthic seascape for the bed of the teaching flume, complete with sea urchin mimics that spawn viscous gamete surrogates. Visitors will be able to experiment with hands-on props such as flow obstacles and a removable bed-roughness section. Several permanent posters and a short video about broadcast spawning in nature will enhance the demonstration. Finally, the PLIF system will be used to make educational movies for dissemination via a digital library of the American Physical Society.

In this project the Principle Investigator will determine how the physics of free-surface oceanic turbulence impacts the success of a reproductive strategy (broadcast spawning) used by corals and other marine invertebrates. The timeliness of the research is punctuated by the worldwide demise of coral reefs. The goals are to use a physics-based investigation to learn about reproduction in the living system and to see how evolutionary adaptations to complex turbulent physics shed light on subtleties of the physics themselves. Broadcast-spawning adult males and females simultaneously extrude sperm and ova into the surrounding flow. Subsequent fertilization relies primarily on turbulent stirring to mix the gametes. Most reef-building corals release buoyant gametes that rise to the free surface, where they are stirred by the free-surface turbulent flow. Buoyant particle paths in free-surface turbulence are compressible, even when the underlying 3D flow is incompressible. This results in regions of buoyant particle coalescence and divergence (corresponding to upwelling). This physical phenomena plays a role in the structure of floating and near-surface particles in the ocean, including foam streaks, oil spills, and the infamous garbage patch in the Pacific, but its effect on fertilization success is unknown. This research program will integrates laboratory experiments and numerical simulations to study the effect of free-surface turbulence on coalescence of initially distant buoyant scalars, and to predict fertilization rates for broadcast spawning corals. The Principle Investigator will integrate research methods into the teaching curriculum as an effective tool for learning fluid mechanics, and use the topic of broadcast spawning as a vehicle for getting K-16 students interested in engineering and science. A hands-on interactive module demonstrating the role of surface turbulence on the spreading and aggregation of buoyant scalars will be developed and used as part of the on-going effort to integrate research topics into outreach activities, many of which directly target women and other underrepresented K-16 students.

The inhalant siphon flows produced by benthic invertebrates such as clams through suspension feeding and respiration can directly affect a wide range of physical and chemical processes in benthic marine ecosystems. This process is energetically costly and influences the feeding and reproductive biology of the individual. Moreover, understanding siphon flows at multiple scales are widely used not only to address questions of flow fields for other aquatic organisms and exchange processes, but have direct impacts on a variety of engineering problems such as designing sewers. Despite the importance of these flow fields in biology, relatively little research has been conducted on this topic. For this study, the PIs have modeled the flow outside the siphon entrance of several important benthic marine and have found radically different results from those commonly assumed. Given these findings, the PIs propose to test the results of their numerical simulation on inanimate physical models, and then verify their accuracy using live organisms.

The proposed numerical modeling will examine and predict effects of several parameters including inhalant siphon wall thickness, siphon height, disturbances caused by exhalant flows, and sensitivity to ambient flows. Predictions will be initially tested by using inanimate analog models. To provide a broad ecological framework, the PIs will then focus on five model suspension feeders, each of which have been extensively studied, and include a species of benthic shrimp, a tunicate, a soft shelled clam, the parchment worm, and a tube dwelling amphipod. This suite species will provide a broad description of the intake flow as each feeding system span nearly all the range of Reynolds numbers observed in animals that produce siphon flows. The results of this study will improve our current understanding the effects of organismal intake flows on near bed processes such as vertical fluxes of organic and inorganic nutrients, an important aspect of benthic ecology. Direct deliverables will include verified quantitative models of inhalant flows of marine benthos, connecting form and function and detailing fluid mechanical costs of operation.

The PIs will partner with the staff of Centers for Ocean Sciences Education Excellence (COSEE) to produce a pair of educational webinars on fluid flows. This series of webinars are targeted toward high school teachers and university professors, and will use concept maps to demonstrate how mathematics, biology, and fluid dynamics can be integrated to answer broad oceanographic questions. Both PIs will continue graduate training in interdisciplinary science and will incorporate examples of the proposed work in their undergraduate and graduate teaching.

One method for remediating contaminated groundwater is to introduce a chemical solution that will react with and degrade the contaminant. This remediation method is most successful if the introduced chemical solution is spread throughout the contaminated area. The porous materials through which groundwater flows are naturally heterogeneous, meaning that water flows more easily through some parts and less easily through others. This heterogeneity naturally causes some spreading, called passive spreading, of the chemical solution into the contaminated groundwater. Additional spreading, called active spreading, can occur by inducing certain time-varying patterns of groundwater flow in the contaminated area. Certain time-varying flows, classified as chaotic advection, are known to substantially enhance active spreading.

Both passive and active spreading lead to enhanced degradation of the contaminant; however, the combined effect of active and passive spreading is not well understood. In this project, a suite of laboratory experiments and numerical simulations will be used (1) to investigate the interplay between passive and active spreading and the role that each plays in enhancing degradation, and (2) to develop strategies for designing chaotic advection patterns for different patterns of heterogeneity. The laboratory experiments will be conducted using novel laser-based optical techniques to visualize and quantify the combined effects of passive and active spreading on contaminant degradation.

Activities such as remediation of contaminated groundwater, extraction of geothermal energy, and certain types of mining of metals all rely on spreading of chemical solutions in porous geological materials. Because of the natural heterogeneity of geological materials, an understanding of the relationship between heterogeneity and chaotic advection and their effects on spreading is critical to the success of these applications. This project will also develop new laboratory techniques that could provide a breakthrough in measurement of reactive transport in porous media.

This project was developed at an NSF Ideas Lab on "Cracking the Olfactory Code" and is jointly funded by the Physics of Living Systems program in the Physics Division, the Mathematical Biology program in the Division of Mathematical Sciences, the Chemistry of Life Processes program in the Chemistry Division, and the Neural Systems Cluster in the Division of Integrative Organismal Systems. The project is a synergistic combination of laboratory experiments and computer modeling that will lead to better understanding of how animals use the sense of smell to navigate in the real world. Almost universally, from flies to mice to dogs, animals use odors to find critical resources, such as food, shelter, and mates. To date, no engineered device can replicate this function and understanding the code used by the brain will lead to many novel applications. Cracking codes, from neural codes to the Enigma code of WWII, is aided by a deep understanding of the content of messages that are being transmitted and how they will be used by their intended receivers. To crack the olfactory code, the team will focus on how odors move in landscapes, how animals extract spatial and temporal cues from odor landscapes, and how they use movement for enhancing these cues while progressing towards their targets. The proposed work encompasses physical measurement of odor plumes, behavioral measurement of animals' paths through olfactory environments, electrophysiological and optical measurement of neural activity during olfactory navigation, perturbations of the environment via virtual reality and of neuronal hardware via genetics, and multilevel mathematical modeling. The PIs will teach and work with undergraduate, graduate and postdoctoral students and especially recruit students from underrepresented groups in science. The project's results may lead to improved methods for the detection of explosives, new olfactory robots to replace trained animals, and new theoretically-grounded advances in robotic control. The project will inform the development of technologies that interfere with the ability of flying insects (including disease vectors and crop pests) to locate their odor target, thus opening a new door for developing 'green' technologies to solve problems that are of global economic and humanitarian importance.

This proposal is a synergistic combination of laboratory experiments and computational modeling that will probe how animals use olfaction to navigate in their environment. Specifically, this effort seeks to solve the difficult problem of olfactory navigation through the following aims: (i) Generate and quantify standardized, naturalistic odor environments that can be used to perform empirical and theoretical tests of navigation strategies; (ii) Determine phenomenological algorithms for odor-guided navigation through behavioral experiments in diverse animal species; (iii) Determine how odor cues for navigation are encoded and used in the nervous system by recording neuronal data and simulating putative neural circuits that implement these processes; (iv) Manipulate olfactory environments and neural circuitry, to evaluate model robustness. In contrast to previous attempts to understand olfactory navigation, the present strategy emphasizes mechanisms that are biologically feasible and explores the wide range of temporal and spatial scales in which animals successfully navigate. The project will generate datasets of immediate use and importance to scientists in theoretical biology and mathematics, engineering (fluid mechanics, electronic olfaction, and robotics) and biology (neuroscience, ecology and evolution).

Animals have a keen ability to find odor sources such as food, partners, pups and predators through the sense of smell in a manner that cannot be replicated by machines. How brains mediate navigation of the environment (the odor plume) through smell is an important unsolved problem. Indeed there are many instances where using machines to navigate an odor landscape is an unmet need to society. For example, even though their training requires lengthy one on one interaction with a trainer, dogs are still used to find explosives in airports and in the battlefield. Our multidisciplinary Odor Plume Neurophotonics (OPeN) team will tackle understanding the brain circuits mediating odor plume navigation. This is a daunting task because it involves characterizing how odors diffuse in the air (environmental engineering), developing advanced miniature microscopes to record from the brain of freely moving animals (electrical and mechanical engineering), recording from brain regions processing odor plume information in real time (systems neuroscience and integrative neurophotonics), and developing mathematical procedures to quantify how the information necessary for successful odor plume navigation is represented in the brain (applied mathematics). Our team will engineer a novel miniature microscope to record activity as mice navigate the odor plume and will assess how the activity of these neurons result in successful odor plume navigation. Furthermore, the team members of OPeN are thoroughly committed to foster advancement of women, underrepresented minorities, veterans and disabled individuals in science and participate in various programs to promote science diversity. Additionally, the team members have a track record of disseminating their work and have an established partnership with a local small business, Intelligent Imaging Innovation, Inc. with world headquarters located in Denver. We will continue our commercial dissemination efforts of the technology developed in this project. Finally, we will endeavor to communicate science to the broader audience through venues such as Scientific American, Public Broadcasting Service and outreach through the Denver Museum of Nature and Science.

Members of our OPeN interdisciplinary team developed a novel two photon fiber-coupled microscope for 3D imaging of brain activity in the freely moving mouse and generated and quantified realistic odor environments in the laboratory to explore algorithms used for odor-guided navigation. In this project we leverage the extensive expertise and achievements of the team to crack the circuit basis for odor plume navigation. We will develop a low-weight, miniature 3-photon fiber coupled microscope (3P-FCM) to record neuronal activity simultaneously in one brain area in two planes of view. In addition, OPeN will develop a portable photoionization (PID) sensor to detect the odorant concentration at the nostril as the animal navigates the odor plume. Members of the OPeN team will record neural activity in the hippocampus and cerebellum of animals navigating the odor plume and will develop a Bayesian analysis method to decode odor plume navigation from neural activity. This multidisciplinary approach will result in understanding of the brain mechanisms of odor plume navigation.

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.

The Odor2Action network consists of 16 investigators from 16 research institutions in the United States, the United Kingdom, and Canada. The composition and scientific goals of the effort are designed to leverage prior investments in neurotechnologies funded by the BRAIN Initiative, other domestic agencies and international partners. Specifically, Odor2Action will address a central question of neuroscience: How do animals use information from odor stimuli in their environment to guide natural behaviors? To synergistically study this problem, the network is subdivided into three interdisciplinary research groups (IRGs); each IRG contains experts in a wide range of experimental and theoretical approaches, and investigates how similar problems are solved by nervous systems in phylogenetically diverse species. IRG1 will test a novel framework for organizing olfactory stimulus space and olfactory codes around the statistical relationships among natural odors. IRG2 will work to understand how neural circuits translate odor signals into dynamic and adaptive behaviors, a critical component of our overall network goal of understanding how natural odors trigger natural behaviors. IRG3 will investigate the physical structure of odor environments and how animal motion and sensory capabilities interact with those environments to detect, discriminate and localize odor objects. Collectively, the network will determine how neural representations of odor are generated, how they are progressively reformatted across successive circuit layers, and how they support useful behaviors. While focusing on olfaction, this project will provide broad and fundamental insights into brain function. This compact circuit architecture associated with olfaction offers unique opportunities to achieve an end-to-end understanding of the core computational logic by which various brains organize and read out such high-dimensional, discrete variables to generate adaptive behaviors. This coordinated project on the neuroscience of olfaction across species will have important societal impacts in science, technology, health, and policy. Given the complexity and high dimensionality of chemical space and its primacy in driving behavior among most species, studying how odor leads to action promises to provide insight into optimal biological solutions for encoding complex information about the external world. Elucidating biological solutions to olfaction can inform the development of algorithms and engineered devices for detection and identification of chemicals in applications that span the range from homeland security to food safety.

The Odor2Action network will address a central question of neuroscience: How do animals use information from odor stimuli in their environment to guide natural behaviors? The network will approach this problem in the context of olfactory-guided behavior as an instance of a much more general problem of many complex brain systems - how are high-dimensional, discrete, and combinatorial variables that are not simply ordered along easily discernible axes represented in brain circuits and mapped to actions? The compact olfactory circuit architecture offers unique opportunities to achieve an end-to-end understanding of the core computational logic by which brains organize and read out such high-dimensional, discrete variables to generate adaptive behaviors. This network will study olfactory systems of mammals and insects, which have independently evolved common structural elements at successive levels of olfactory processing in their central nervous systems. These common elements possibly reflect convergent evolution towards a set of similar solutions to shared olfactory problems. The network comprises three interdisciplinary research groups (IRGs) that are designed around specific elements of an end-to-end investigation of olfaction. IRG1 aims to understand the first stages of how neural representations of odor are generated, and how they are progressively reformatted across successive circuit layers to support meaningful behaviors. IRG2 aims to understand how neural circuits translate odor signals into dynamic and adaptive behaviors, a critical component of our overall network goal of understanding how natural odors trigger natural behaviors. IRG3 will investigate the physical structure of odor environments and how animal motion and sensory capabilities interact with those environments to detect, discriminate and localize odor objects. Each IRG integrates theory and experimental approaches in two or more species in ways that produce complementary, synergistic interactions across levels of biological analysis.

This Neuronex award is co-funded by the Division of Emerging Frontiers and the Behavioral Systems Cluster within the Directorate for Biological Sciences, the Office of Advanced Cyberinfrastructure within the Directorate for Computer and Information Sciences, the Mathematical Biology Program and the Physics of Living Systems Program within the Directorate for Mathematical and Physical Sciences, as part of the BRAIN Initiative and NSF's Understanding the Brain activities.

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.