Brian Mitchell - US grants

Several studies in recent years have confirmed that both the crust and upper mantle beneath oceanic regions are anisotropic in their elastic properties. We propose to study the nature of that anisotropy by comparisons of observed waveforms recorded at regional and near distances with those calculated for models of generalized anisotropy which can include up to 13 eleastic constants and which can vary from layer to layer in magnitude and direction. By restricting our observations to waves which have traveled short distances we will minimize any effects of lateral heterogeneity of velocity structure on wave forms, increase the likelihood that the orientation and magnitude of anisotropy is uniform along that path, and, if paths of different distances are available, may be able to separate the effects of varying anisotropic structure in the upper crust, lower crust, and upper mantle. In addition, since short paths are used, it will be possible to use small events which are numerous in many parts of the Pacific.

This research is to utilize the Saint Louis University seismometer network to study heterogeneities in the New Madrid intraplate earthquake zone. A new series expansion method will be use to develop path Green's functions on source locations from small, less than magnitude 2.5, earthquakes. Then, the Green's function method will be applied to larger earthquakes in the New Madrid region to study spatial/temporal variations in rupture properties. A second investigation will utilize the S-wave coda to map three-dimensional Q structure in the New Madrid seismic zone. These studies should provide insights on the nature of heterogeneities within and near the source zone of New Madrid earthquakes. This is important both for knowledge of earthquake processes in intraplate regions and for assessing earthquake hazard. This research is a component of the National Earthquake Hazard Reduction Program.

9706720 Mitchell This research involves the mapping of attenuative dispersion along paths through the source zone of New Madrid earthquakes as well as along paths outside of, but contiguous to, that zone. Both theoretical and observational research has shown that waves which have been attenuated by either intrinsic anelasticity or by scattering processes also exhibit dispersion. Attenuative dispersion associated with regional seismic phases has been found to be easily measurable in regions where those phases attenuate rapidly with distance. Abundant amounts of data obtained from PANDA stations, as well as from USNSN stations, in and surrounding the New Madrid seismic zone should be available for these studies. Relating the variation of Q to the properties of the crust may provide new information on earthquake processes in the New Madrid region. This research is a component of the National Earthquake Hazard Reduction Program. ***

9905328
Mitchell

This award provides funding for the construction and testing of a prototype beam-balance tiltmeter to be used in seismometer installations to remove noise in the seismic (ground motion) signal that is due to the effect of tilting of the ground at the observation point. Such a device will improve the signal-to-noise-ratio of modern broadband seismometry. The instrument development and construction will be carried out in the Department of Earth and Atmospheric Sciences at Saint Louis University.
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The goal of this research project is to produce a novel class of aluminum matrix nanocomposites with superior structural and corrosion-resistance properties that can be manufactured rapidly and uniformly. The nanocomposites are formed by first producing aluminum and mullite nanoparticles using high-energy ball milling (mechanical attrition). The nanocrystalline powders are then processed to near net-shape composites using Hot Isostatic Pressing (HIP). Further, the incorporation of design innovations to improve the speed and uniformity with which these nanocomposites are formed are being investigated. Specific tasks include the development and evaluation of a fluidized bed process for the continuous milling of nanocrystalline materials. Oxidative milling will be incorporated in the fluidized bed process in order to form intimate mixtures of nanocrystalline aluminum and ceramic, that can then be further processed via HIP.

Characterization of the interfacial, mechanical, and corrosion properties of nanocrystalline mullite-reinforced nanocrystalline aluminum matrix composites will be conducted. Mechanical properties are to be characterized using nanoindentation and traditional tensile testing. Corrosion studies will be carried out to determine the effects of nanocrystallinity on chemical resistance. The project will provide research experiences for undergraduates involved in the Louisiana Alliance for Minority Participation (LAMP). It is expected that LAMP students from Dillard, Southern and Xavier will participate and be encouraged to pursue advanced degrees.

0214259
Koper

This grant provides partial support for an upgrade of the high-performance computing environment for geophysicists at Saint Louis University. Research carried out by the group is wide-ranging and includes Earth structure studies, seismic source studies, seismic hazard analysis, application of space-based remote sensing data to tectonic problems, and development of freely distributed software. The grant will especially benefit three recently hired assistant professors (Koper, Kusky and Zhu) in establishing research programs.

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0217493
Mitchell

Description:
This award is for support of a joint research project by Dr. Brian Mitchell, Dr. Lupei Zhu, both at the Department of Earth and Atmospheric Sciences at Saint Louis University, Saint Louis, Missouri and Dr. Nihal Akyol, Department of Geophysical Engineering at Dokuz Eylul University, Izmir, Turkey. They plan to conduct a seismological study of the western part of Turkey using groups of both high-frequency (2 Hz) and broadband seismographs. They plan to use data from the high-frequency linear array to obtain a two-dimensional structural model of the grabens and underlying rock by using teleseismsic receiver functions and employing a stacking procedure recently developed by Dr. Zhu. They will use both the linear array and regional array recordings of local earthquakes to perform a combined inversion for precise event location and a tomographic velocity model of the region, and will use data from the broadband instruments for several additional studies. Objectives of this project are to obtain models for velocity structure, including possible anisotropy, for the region, to ascertain the degree of agreement or disagreement among crust/upper mantle models of anisotropy obtained in different locations and by different methods, to infer from those models the directions and consistency of mantle flow and orientation of the crustal stress fields, and to determine the best methods for obtaining information on anisotropic structure in a region of complex structure and tectonics.

Scope:
The selected sites of this study are particularly suitable for the proposed research. Western Turkey is one of the most seismically active continental regions in the world, and much of it is undergoing extensive north-south extensional deformation. Because the region experiences a large number of low to medium-magnitude earthquakes it is particularly suitable for a seismological study of the continental crust in Eurasia. The region's high attenuation values have been attributed to fluid-filled cracks, which tend to cause the crust to be anisotropic. The project will lead to a better understanding of the tectonics of Western Anatolia, which comprises a portion of the Tethysides orogenic belt. The project will enhance international collaborations between scientists in the U.S. and in Turkey. It will involve a recent PhD (Zhu), as well as collaboration with and training of a female seismologist from Turkey.

Many important composite materials are made by melt infiltration, in which polymers or metals are infiltrated into fibrous preforms. To minimize post-processing and machining, it is desirable to create parts directly from the impregnation step, a procedure called net-shape fabrication. While numerical simulation is a crucial part of process design, standard models operate at the continuum scale (i.e., the underlying fiber matrix is viewed as a continuum phase). This approach is necessary for practical reasons, but it requires significant empiricism to generate spatially averaged constitutive equations and parameters. Furthermore, current empirical techniques do not effectively account for important microcscale phenomena such as fiber anisotropy, wetting effects, and void formation during impregnation.

In this collaborative research project conducted by researchers at Louisiana State University and Tulane University, state-of-the-art microscale modeling techniques will be applied to the impregnation process, which will allow analyses to be performed using first principles. Experiments will be performed to aid in the model development and to validate its quantitative capabilities. In a second phase of the research, results from the microscale simulations will be scaled up and transferred to continuum-scale models for net-shape fabrication. The ultimate goal is for this multiple-scale approach to replace much of the empiricism associated with current methods, thereby improving fabrication techniques. The collaborative nature of this project will provide unique learning opportunities for undergraduate and graduate students, with graduate students from LSU participating in experimental aspects of the research at Tulane, and undergraduates from both institutions being included in research meetings at LSU. In addition, active participation in the Louisiana Alliance for Minority Participation is planed to provide summer research opportunities for students from under-represented groups.

The scanning electron microscope system will be used to carry out a wide range of innovative research projects ranging from the understanding of nanomaterials to the fine structures inherent in biological systems. In the nanomaterials research, the instrument will be used to examine the structure of thin films and extended hierarchical structures. These studies will lead to the development of new catalysts and membranes, photovoltaic and thermoelectric devices, and in the development of lightweight composite structures. The studies will also lead to new avenues to manufacture nanostructured materials. In biology, the research will help define the fine structures of freshwater fishes, such as tail neuromasts in darters and lip-surface anatomy in suckers, in order to refine their taxonomy and systematics. This work will lead to a better understanding of freshwater fish biodiversity in North America.

The proposed instrument acquisition will greatly improve the infrastructure for research and education at Tulane University. It will be housed in the Coordinated Instrumentation Facility (CIF) at Tulane, which is a facility that operates and maintains university-wide shared instrumentation. The instrument will be available to the entire university community and will enhance excellence in graduate and undergraduate education at Tulane. The proposed instrument will be used in training and class demonstrations and will provide research opportunities for both undergraduate and graduate students. This acquisition will play an important role in encouraging the participation of underrepresented groups in the areas of science and engineering, through such existing programs as the Louisiana Alliance for Minority Participation (LAMP), the Tulane/Xavier combined degree program, and the Graduate Alliance Program (GAELA). In addition, this acquisition will help to attract high-quality students and faculty to Tulane University.

Silicon nanoparticles with alkyl-functionalized surfaces formed by mechanochemical methods are the focus of these investigations. In the mechanochemical process, silicon is comminuted in size using mechanical attrition in the presence of a reactive organic liquid. As fresh surface silicon atoms are exposed in the comminution process, they react with the organic medium to create functionalized nanoparticles. The scientific merit of the research lies in three specific goals: 1) to extend the concept to new chemistries including alkynes, alkenes, and dienes and their heteroatom anologues; 2) to evaluate process innovations that lead to the rapid production of uniform-sized functionalized nanoparticles via mechanochemical synthesis; and 3) to model the solubility and phase behavior of surface functionalized nanoparticles. The use of "click" chemistry will be explored as a way of increasing the complexity of the silicon surface and to create a functional architecture. New functionalized nanoparticles will be characterized primarily for their optoelectronic properties. Molecular dynamics simulations will be used to elucidate the effect of surface chain length on phase behavior and interparticle forces the lead to phase separation. Process innovations will be achieved through the study of multi-phase mechanochemical synthesis which will open new avenues to nanoparticle functionalization, separation, and production.

Broader impacts include the potential applications for functionalized silicon nanoparticles in the areas of fluorescent biological staining labels, nanoparticle lasers, and solar energy. Educational and outreach activities include research experiences for undergraduates, minority participation in research projects, and international research opportunities through the German Academic Exchange Program.

Abstract


Principal Investigator: Randolph S. Duran

Proposal: EPS-1047309

Institution: Louisiana State University

Title: Exploring a Louisiana Academy of NSF CAREER Awardees, LANCA

This proposers seek to seed the collaborative engagement of Louisiana?s NSF Faculty Early Career Development (CAREER) awardees (collectively defined as Presidential Young Investigators (PYIs), NSF Young Investigators (NYIs), and CAREER awardees) and establish a mechanism to assess and evaluate the impact of this group?s collaborative efforts on the science and education enterprise within in the state. In addition, the proposers will explore seeding similar collaborative efforts in nine other EPSCoR jurisdictions. The proposers envision a two-day conference that will include participants from twenty-two of Louisiana?s institutions that provide baccalaureate or higher degrees, including four Historically Black Colleges and Universities (HBCUs). The targeted institutions represent a broad range - public, private, regional, minority serving, research intensive, and primarily undergraduate. Invited participants from other EPSCoR jurisdictions will have a role in evaluating the workshop?s effectiveness and in seeding collaborations of CAREER awardees within their respective jurisdictions.

Intellectual Merit: The intellectual merit centers on establishing an eminent community of CAREER awardees whose collaborations could significantly strengthen the STEM research and education enterprise of several EPSCoR jurisdictions located primarily in the southeastern United States. The intellectual merit is associated with seeding the proposed organization of a ?Louisiana Academy of NSF CAREER Awardees? (LANCA) which could be adapted and/or adopted by other jurisdictions. The resulting ?academies? would seek to: (i) enhance continued career development of awardees, (ii) coordinate and strengthen educational/outreach activities within the jurisdictions, (iii) systematically identify, encourage and mentor potential future CAREER awardees, and (iv) undertake additional scientific, policy, and service activities determined collectively by the participants, and (v) serve as a resource to stimulate collaborations across the jurisdictions and to assist young faculty in applying for CAREER awards.
Broader Impacts: The potential broader impacts of a cohesive, highly motivated group of ?young? investigators who are committed to STEM research and education for the benefit of next generation scientists and engineers could have a transformative impact on the STEM research and education enterprise of Louisiana. Additional broader impacts of the proposed work lie in the use of outcomes from the evaluation and assessment of the group?s efforts and the dissemination of that information to other EPSCoR jurisdictions for their use in initiating similar partnerships. Assessment categories will include the impact of the NSF funding on the awardees via trends in retention, longitudinal grant and professional success, and other indicators.

Project Summary: The directed beating of motile cilia is a critical aspect of tissue function in a variety of developmental and physiological contexts including proper neural development, egg migration through the oviduct and mucus clearance in the respiratory tract. The loss of cilia motility results in a wide range of phenotypes including hydrocephaly, infertility, situs inversus, and respiratory dysfunction. We have developed the ciliated epithelium of Xenopus larval skin as a model system to ask: How do ciliated cells generate, maintain and ultimately destroy hundreds of cilia and how do they orient those cilia in an organized way? We have developed numerous light microscopic methods for visualizing specific aspects of ciliated cells in the developing skin of Xenopus embryos. Specific to this application we have implemented the use of LITE sheet microscopy. These methods will allow us to visualize the massive centriole duplication required to generate the approximately 150 basal bodies that nucleate the cilia with significantly improved temporal resolution. Additionally, we can visualize and accurately quantify the cytoskeletal interactions that facilitate the establishment of cilia orientation. Using these methods we will address: (1.) Regulation of cytoskeletal dynamics during the polarization of ciliated epithelia, (2.) The regulation of centriole amplification, and (3.) The transdifferentiation of MCCs. Our results will provide an important link between polarity cues, hydrodynamic forces and the regulation of cytoskeletal dynamics during cellular polarization. Additionally, we will continue our efforts to understand the regulation of centriole biogenesis but expand this work to include the scaling mechanism that regulate centriole number. Finally, we will develop the MCCs of Xenopus as a novel model to understand the molecular regulation of transdifferentiation. While our work is focused on ciliated epithelia, the cell and developmental mechanisms we discover will be broadly applicable. The connection between cytoskeletal dynamics and cell polarity is widely accepted in numerous developmental and disease contexts, and our experiments will likely uncover both MCC specific and more general mechanistic features of this connection. Additionally, defects in centriole duplication highly correlate with late stage cancer progression, indicating an uncoupling of duplication from normal cell cycle progression. The cellular process of transdifferentiation is important during regeneration and cancer progression. Our experiments will provide important developmental control over this process allowing us to uncover novel aspects of coupling transcriptional regulation and autophagocytic recycling.

The epidermis is composed of multiple layers of keratinocytes that are tightly anchored to one another by intercellular junctional complexes. These adhesive junctions maintain tissue integrity and help create a physical barrier with the outside world limiting both water loss and the influx of allergens and infectious material. Consequently, defects in adhesion lead to skin fragility and blistering diseases and have been associated with the development of inflammatory skin diseases. Importantly, intercellular junctions and their associated cytoskeleton are not static structures. Certain cells, such as melanocytes, lymphocytes and dendritic cells, must have the ability to temporarily break these junctions as they migrate into the epidermis or send out processes between neighboring keratinocytes. Very little is known about how keratinocytes reorganize their cell-cell contacts in response to invading cells.

Project Summary: The ability of cells to migrate in a directed manner is critical to a variety of biological processes including morphogenesis, would repair, immunological response and cancer progression. A key feature of migration in an in vivo setting is the ability to break through junctional barriers as a cell migrates across tissue boundaries. This ability requires a distinct set of molecular regulators and requires manipulation of cytoskeletal dynamics. We have developed the migration and radial intercalation of multi-ciliated cells (MCCs) and ionocytes (ICs) in the skin of Xenopus embryos as an experimentally pliable model system for addressing the molecular mechanisms involved as these cells break through the epithelium. Our data indicates that diverse regulators of microtubule (MT) stability have profound effects on the ability of these cells to break through junctional barriers. We have developed the molecular tools and imaging techniques to manipulate, visualize and quantifiably score the ability of MCCs and ICs to migrate towards the apical surface and intercalate into the outer epithelium. We will use these methods to address: (1) Establishment of stabilized MTs along the axis of migration, (2) Junctional remodeling during intercalation, (3) Small GTPase regulation of intercalation. The results from these experiments will provide a detailed molecular mechanism for the complex regulation of MT dynamics during migration and intercalation. While many of these experiments build on migration studies in cell culture, our preliminary data indicates that the in vivo 3 dimensional aspect of our proposed experiments will provide a novel paradigm for understanding this important biological problem. The ability to block cells from traversing junctional barriers could have a significant impact on human health as the ability of metastatic cancers cells to migrate through tissue barriers is a critical step in cancer progression. The unique ability to address the issue of intercalation in distinct cells types will allow us to identify core components of the process. Additionally, the profound reproducibility of intercalation during a discreet developmental window will allow us to identify subtle phenotypes in a quantifiably robust manner that would not be feasible in many other experimental systems.

The development of global competencies in advanced degreed holders in STEM fields is critical to innovation, competitiveness, and economic development in the increasingly international marketplace of science and engineering. This workshop brings together experts from different types of organizations (universities, non-profit entities, funding agencies, private sector) that participate, engage in, or have significant roles in STEM graduate education/training programs to formulate a series of recommendations on how best to structure programs that provide international experiences for graduate students. The goal would be to identify the most efficient ways to support graduate students in their development of global competencies that will not increase time-to-degree or detract from their technical contributions. The workshop also explores related topics such as how to provide international research experiences to students from under-represented groups and those who are economically disadvantaged. This event addresses concerns common to international research experiences for graduate students across all STEM disciplines. Attendees/participants include representatives from the natural sciences, biological sciences, physical sciences, engineering, and social sciences; experts in educational psychology, program evaluation, and international relations add to the breadth of the conversation.

The main goals of the workshop are to address the following topical research questions;
-- What is the appropriate role of the student's faculty research advisor (research mentor) in identifying, defining, permitting, and evaluating the advisee's international research activity?
-- What are the appropriate timing and duration for introductory, follow-on, and subsequent international research experiences during a STEM PhD student's education/training? What about a STEM master's student?
-- What are the appropriate entities/metrics for assessing the international research activity experiences, defining the appropriate assessment tools, collecting and archiving data, and conducting longitudinal studies on international research experiences?

Presenters/attendees are selected by the organizing committee to reflect as broad a view as possible, including those calling for major changes in how international research activities are structured and funded. The outcomes of the workshop will be a publicly-accessible report with recommendations to the higher education, industry, non-profit, and governmental agency communities on how to improve global skills development in STEM advanced degree holders through effective international research 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.