Granville, OH, United States
Granville, OH, United States

Denison University is a private, coeducational, and residential liberal arts college in Granville, Ohio, United States, about 30 miles east of Columbus, the state capital. Founded in 1831, it is Ohio's second-oldest liberal arts college. Denison is a member of the Five Colleges of Ohio and the Great Lakes Colleges Association, and competes in the North Coast Athletic Conference. Wikipedia.


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Motivated by recent observations that show increasing fractional linear polarization with increasing wavelength in a small number of optically thin jet features, i.e., "inverse depolarization," we present a physical model that can explain this effect and may provide a new and complementary probe of the low-energy particle population and possible helical magnetic fields in extragalactic radio jets. In our model, structural inhomogeneities in the jet magnetic field create cancellation of polarization along the line of sight. Internal Faraday rotation, which increases like wavelength squared, acts to align the polarization from the far and near sides of the jet, leading to increased polarization at longer wavelengths. Structural inhomogeneities of the right type are naturally produced in helical magnetic fields and will also appear in randomly tangled magnetic fields. We explore both alternatives and find that, for random fields, the length scale for tangling cannot be too small a fraction of the jet diameter and still be consistent with the relatively high levels of fractional polarization observed in these features. We also find that helical magnetic fields naturally produce transverse structure for inverse depolarization which may be observable even in partially resolved jets. © 2012. The American Astronomical Society. All rights reserved.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: AMO Experiment/Atomic, Molecul | Award Amount: 308.86K | Year: 2014

Non-technical description:
Lasers and other light sources will be used to measure the properties of negative ions, which are atoms and molecules that have an extra electron. High-precision measurements of how tightly the extra electron is bound will be useful for modeling chemical reactions and plasma interactions for such practical applications as the manufacturing of semiconductors for computers and other electronic devices. The detailed studies of negative ions will yield insights into dynamical many-body interactions which are central to understanding how collections of particles behave differently from what one would expect from the knowledge gained by studying single particles in isolation. These interactions are general phenomenon of interest for a broad range of fields in physics, chemistry, and materials science, including nanotechnology. The project will enhance the research and teaching infrastructure of Denison University, an undergraduate college. Students will participate in the experiments both on-campus and at the Lawrence Berkeley National Laboratory, providing important research experiences for young scientists including technical training in electronics, computers, lasers, and optics.

Technical description:
This project studies the interactions of photons with negative ions in two related series of experiments. The extra electron in a negative ion is bound predominantly by electron correlation effects and therefore negative ions provide a fertile testing ground for state-of-the-art atomic physics calculations regarding these multi-body interactions. In the first series of experiments, complex atomic negative ions are investigated on-campus at Denison University using tunable infrared laser light to detach outer-shell electrons. The ground and upper state photodetachment thresholds of several lanthanide and Group III negative ions (gallium and possibly thallium) will be measured in order to determine the electron affinities and energy levels. There is currently strong disagreement between theoretical predictions and experimental photoelectron spectroscopy results for these systems. The faculty and student researchers will also investigate resonances and bound excited states in lanthanide ions including bound-bound electric-dipole transitions that exist in the negative ions of cerium and lanthanum. The second series of complementary experiments will investigate inner-shell photodetachment from the negative ions of oxygen, hydrogen, and carbon chains of n numbers of carbon atoms (O-, H-, C_n-) and other atomic and molecular species using high energy (12-1000 eV) photons at the Advanced Light Source synchrotron. These experiments continue the PIs investigations into the effects of the outer-shell electrons on the detaching inner electrons wavefunction. The dynamic multi-electron interactions in the photoexcitation of the highly correlated cores of negative ions continue to challenge the fundamental understanding of atomic structure. Investigations into heavy negative ions and detection of the neutral decay products will test the latest theories describing inner-shell photodetachment.


Grant
Agency: NSF | Branch: Continuing grant | Program: | Phase: | Award Amount: 274.00K | Year: 2011

This project studies the interactions of photons with negative ions in two related series of experiments. The extra electron in a negative ion is bound predominantly by electron correlation effects and therefore negative ions provide a fertile testing ground for state-of-the-art atomic physics calculations regarding these multi-body interactions. In the first series of experiments, complex atomic negative ions are investigated on-campus at Denison University using tunable infrared laser light to detach outer-shell electrons. The ground state photodetachment thresholds of several lanthanide and Group III negative ions will be measured in order to determine the atomic electron affinities. There is currently strong disagreement between theoretical predictions and experimental photoelectron spectroscopy results for these systems. The faculty and student researchers will also investigate resonances and bound excited states in lanthanide ions including bound-bound electric-dipole transitions that appear to exist in the negative ions of Ce and La. The second series of complementary experiments will investigate inner-shell photodetachment from the negative ions of oxygen, C60 and other atomic and molecular species using high energy photons at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. These experiments continue a series of studies by the PIs to investigate the effects of the outer-shell electrons on the detaching inner electrons wavefunction. The dynamic multi-electron interactions in the photoexcitation of the highly correlated cores of negative ions continue to challenge the fundamental understanding of atomic structure. Investigations into heavy negative ions and detection of the neutral decay products will test the latest theories describing inner-shell photodetachment.

The broader impacts of the program include contributions to the database of atomic properties, connections to other scientific fields, and the education of undergraduate students. The high-precision electron affinities measured in this project will be useful for modeling of chemical reactions and plasma interactions for such practical applications as semiconductor processing. The detailed studies of negative ions will yield insights into dynamical many-body interaction, which is a general phenomenon of interest for a broad range of fields in physics, chemistry, and materials science, including nanotechnology. The project will enhance the research and teaching infrastructure of Denison University, an undergraduate college. Students will participate in the experiments both on-campus and at the ALS, providing important research experiences for young scientists including technical training in electronics, computers, lasers, and optics. Additionally, both PIs and many of our Undergraduate students are also heavily involved with student-faculty collaborative public science outreach projects that present Physics and Astronomy programs to hundreds of people each year.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 105.30K | Year: 2015

This Major Research Instrumentation program (MRI) award will support the acquisition of a bench-top powder X-ray diffractometer (XRD) system at Denison University. This instrument will be used in the research of at least five faculty members at Denison. The breadth of the research includes development of new types of liquid crystals for use in organic electronics and solar cells, novel bio-sensors for disease detection, new catalysts for the generation of solar fuels, and understanding water transport in waxy layers related to hydration control in plants. Denison University is a primarily undergraduate institution, meaning that the research supported by the the new instrument is carried out exclusively with undergraduate researchers mentored directly by faculty. Undergraduate students will be trained as independent users of powder XRD, gaining significant hands-on experience and enhanced research training. In addition, the instrument will be incorporated into several classes in the science curriculum, including classes in general chemistry, inorganic chemistry, materials chemistry, and geoscience. The use of cutting edge equipment across Denisons curriculum promotes an increased student awareness of the critical role fundamental science plays in technological innovation and in finding solutions for many of the critical issues facing the Nation.

With a compact bench top design and advanced capabilities such as incorporation of the ALTK-450 variable temperature (VT) stage, the ADX-8000 powder XRD system will have significant and immediate impact on multiple ongoing research areas in the department in diverse areas of functional materials research. These include (1) research in novel columnar liquid crystalline materials with potential to serve as components in a range of organic electronic applications, including low-cost photovoltaics; (2) research on low-cost solar energy conversion, with the development of mixed metal-oxide nanomaterials; (3) research in well-ordered organo-silicate materials with the potential to serve as biochemically active materials and sensors; (4) research on the complex phase behavior of wax layers mimicking natural boundary layers.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 33.52K | Year: 2012

This proposal is to fund the Undergraduate Knot Theory Conference 2012 to bring together undergraduates and undergraduate faculty interested in knot theory, to be held at Denison University from July 15-18, 2012. Knot theory is a field very amenable to research by undergraduates. There are a variety of REU programs with a knot theory component. Moreover, there are many faculty members who would like to involve their students in undergraduate research in knot theory. This conference will bring together experts in knot theory with undergraduates who are either currently participating in knot theory REUs, undergraduates who have participated in knot theory research, current graduate students who participated as undergraduates in knot theory research, and perhaps most importantly, faculty who either have involved undergraduates in knot theory research or who would like to involve undergraduates.

As a centerpiece, we will have a collective problem session to give participants numerous ideas for future research directions. This conference will provide an opportunity for students to experience a mathematics research conference that is specifically designed and directed toward them. Moreover, the conference will establish a supportive network of students and faculty with an interest in knot theory research, thus furthering the involvement of students in the field of mathematics. The conference URL is www.denison.edu/unknot.


Grant
Agency: NSF | Branch: Continuing grant | Program: | Phase: | Award Amount: 200.00K | Year: 2012

The Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry supports Joseph J. Reczek of Denison University in this project to design, synthesize and characterize new donor-acceptor columnar liquid crystals as organic electronic materials. The approach involves development of synthetic methodologies for the generation of highly substituted aromatic compounds with the ability to self-assemble into a variety of ordered, functional materials. The optical and electrical properties of these fundamentally new materials will be investigated towards novel components for photovoltaics and other optoelectronic applications.

This project will engage a cohort of undergraduate students in interdisciplinary research at Denison University, a primarily undergraduate institution. These students will be trained in cutting-edge techniques and instrumentation related to several branches of chemistry, including organic synthesis, molecular self-assembly, materials chemistry, and device fabrication. Students will gain experience in teamwork, leadership, and project management, as well as giving scientific presentations in the local community and at national conferences. New instrumentation supported will broadly affect research and teaching at Denison. The proposed work could significantly impact the fields of self-assembly, organic electronic materials, and photovoltaics, while training undergraduate students for success in scientific careers and post-graduate education as well as raising awareness of alternative energy research in the community.


Grant
Agency: NSF | Branch: Continuing grant | Program: | Phase: Physiolg Mechansms&Biomechancs | Award Amount: 92.07K | Year: 2015

The sliding filament theory is widely accepted as a useful model of muscle contraction in isolated preparations. However, the theory fails to account for critically important characteristics of muscle function. Despite decades of work, a predictive model of muscle force during natural movements remains elusive. The researchers will test the hypothesis that important properties of muscle can be explained by the winding filament hypothesis. The proposed work has significant potential to inform our understanding of how neural activation and applied forces together determine in vivo muscle force. Results from the research will be integrated into graduate and/or undergraduate courses at Denison University (RUI-eligible), Northwestern University, and Northern Arizona University. In addition, the research team will leverage programs at Denison University and Northern Arizona University for recruiting under-represented participants in research. Results will be disseminated to broad audiences through standard mechanisms of publication and diverse public media, as well as participation in interdisciplinary conferences in the areas of engineering, biomechanics, and physiology.

The researchers will use the mdm mouse to test predictions of the winding filament hypothesis. The winding hypothesis claims that, in addition to the thin filaments, titin is activated by Ca2+, and that cross-bridges not only translate but also rotate the thin filaments, storing elastic energy in PEVK titin during isometric force development. Due to constraints of sarcomere geometry on titin activation and winding, the hypothesis makes unique quantitative predictions about the effects of stimulation and length changes on muscle force. By including different muscles in the proposed studies, the researchers can determine whether naturally occurring variation in titin structure and function contributes to activation- and length-dependent muscle properties (e.g., doublet potentiation and force depression/enhancement). The experiments will test whether titin activation and winding, alone or in combination, can account for observed muscle forces by comparing experimental results to model predictions.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 39.35K | Year: 2016

This proposal is to fund the Undergraduate Knot Theory Conference 2016 to bring together undergraduates and undergraduate faculty interested in knot theory, to be held at Denison University from July 31 to August 2, 2016 as a satellite conference to 2016 MathFest which will take place in Columbus, OH. Knot theory is a field very amenable to research by undergraduates. There are a variety of REU programs with a knot theory component. Moreover, there are many faculty members who would like to involve their students in undergraduate research in knot theory. This conference will bring together experts in knot theory with undergraduates who are either currently participating in knot theory REUs, undergraduates who have participated in knot theory research, current graduate students who participated as undergraduates in knot theory research, and perhaps most importantly, faculty who either have involved undergraduates in knot theory research or who would like to involve undergraduates.

As a centerpiece, the organizers plan to have a collective problem session to give participants numerous ideas for future research directions. This conference will provide an opportunity for students to experience a mathematics research conference that is specifically designed and directed toward them. Moreover, the conference will establish a supportive network of students and faculty with an interest in knot theory research, thus furthering the involvement of students in the field of mathematics. The conference URL is www.denison.edu/unknot.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: PETROLOGY AND GEOCHEMISTRY | Award Amount: 50.64K | Year: 2013

This project will produce advances in pure science with broader impacts in public safety and education. The Lassen volcanic center had its last major eruption in 1915 at Lassen Peak, and it is located beneath many of the flight paths of airlines that connect cities in the western U.S. An understanding of how and why volcanic eruptions are triggered at Lassen Peak thus will play a key role in future hazards assessments. Our study brings together researchers with a wide variety of expertise to examine several processes operating prior to eruption, including eruption triggers and magma storage. For example, prior work shows several mechanisms by which an eruption even may be triggered. One line of thought is that eruptions are triggered soon after new magma is introduced into a magma reservoir beneath a volcano, as new magmas mix with magmas already present in a shallow chamber. Alternatively, new magma inputs may need to cool, and partially crystallize before an eruption occurs. This cooling drives water into the remaining uncrystallized magma, which increases pressure within the magmatic system if enough water is concentrated into the magma to form a vapor phase. Expansion of the vapor phase may crack the overlying rock and allow an eruption to occur. Lassen provides an important testing ground for these ideas because the two most recent eruptive episodes (1915 at Lassen Peak, and the earlier eruption at approximately 1144 AD at Chaos Crags) both show evidence for pre-eruption magma inputs, but those fresh inputs acted very differently in the two cases. Thus a comparison of the two eruptions will provide insight into the importance of different triggering mechanisms in the Lassen magma system. This study will bring together researchers and students across the spectrum of universities, with representatives from major research institutions, state service universities and a liberal arts college. This will enhance the education of many students, as it provides valuable opportunities to support under-represented groups (Hispanics and women) at both the undergraduate and graduate level, to work in laboratories and with researchers across the globe. In addition, many undergraduates at CSU Fresno will participate in the research as research projects are routinely integrated into the laboratory requirements for core courses.

To attack the research problems outlined above, we will perform a collaborative study of the relationships between magma recharge (fresh inputs of magma), magma mixing and eruption, in the Chaos Crags and 1915 eruptions of the Lassen Volcanic Center, California. The study will use a combination of textural studies to assess crystallization processes, U-series (radiometric) and diffusion profile methods for age dating, and mineral-melt and fluid inclusion studies to delimit pressures and temperatures of magma storage. The specific targets of investigation are the 6 domes of Chaos Crags (denoted as A to F), and the more well-mixed 1915 eruptive products at Lassen Peak. At Lassen Peak, magmas mixed intimately prior to eruption, while at Chaos Crags, mixing was for some reason inhibited. Does this contrast reflect (a) the timing between fresh magma inputs and eruption; (b) contrasts in temperatures and depths of magma storage/interaction or; (c) the relative amounts of hot fresh magma inputs compared to the cooler magmas that already inhabit the chamber (left-over from some prior magmatic episode)? The Chaos Crags units are of special interest because Dome A shows little evidence of mixing?and so yields the most extreme felsic and mafic compositions; all other domes, and the 1915 lavas, fall between these extremes. Dome A thus provides access to end-member magmas. The Chaos Crags and Lassen Peak suites also expose interesting textural contrasts as the Chaos Crags rocks are more crystalline, and their enclaves show a greater variety of quenching textures, which suggests a relationship between mixing and recharge. Key questions include: (1) Does recharge of a chamber with mafic magma trigger mixing (and eventually, eruption), or is there a time lag between recharge and mixing? (2) What effect does a time lag between the initial intrusion of felsic magma and the later intrusion of mafic recharge magma have on the efficacy of mixing and the time scale of eruption? (3) Does the ratio of mafic recharge/resident felsic magma affect mixing and/or the timing of eruption? (4) Do the depths and temperatures of magma storage affect the mixing/eruption process?


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 43.70K | Year: 2012

Troubleshooting undesirable network events, such as poor connectivity or performance, is difficult at best. The high-speed link techniques that work on LANs, such as dumping packets and analyzing the detailed traffic, are impossible due to massive data volume. This project will explore mathematical techniques and network tools that will reduce the amount of data that has to be captured and stored while still allowing network operators to troubleshoot their networks. The projects objective is to extract from high-speed packet streams on individual network links an approximate and highly compressed representation of the link traffic that is orders of magnitude smaller in size than the raw traffic stream but which permits almost the same degree of troubleshooting as the raw data. The project will develop the algorithms and mathematical theory needed to design intelligent sampling algorithms for compressing network traffic. Specific areas to be studied for purposes of developing sampling techniques include identifying what constitutes the representative flows for troubleshooting purposes and investigating how to best encode and decode the sampled data, and how the samples can be gracefully shrunk over time so as to reclaim space for new data as they arrive.

Broader Impact:
The project will provide research experience for undergraduates. Undergraduates at Georgia Tech, Denison and other institutions will be recruited via undergraduate workshops and research symposiums. Additionally, the project will integrate education and research via inclusion of the research into courses. In addition to publishing in appropriate scientific venues, the PIs will expand the Wikipedia entries on topics related to data streaming algorithms as part of the process of disseminating general information about the topic area to the scientific community. In terms of commercial impact, the project will lead to better methods for the diagnosis of large-scale networks, thereby reducing the cost to maintain and operate them. As part of the transfer of research findings into commercial practice the PIs will collaborate with members of AT&Ts Network Management and Engineering Department.

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