College of Liberal Arts and Sciences Chemistry

10564

Quantifying groundwater flow to a subtropical spring-fed river using automated Rn-222 measurement

In karst systems, groundwater and surface water are closely interconnected and are functionally inter-dependent. Intrusion of contaminated river water into the aquifer system may thus degrade groundwater quality, whereas discharge of nutrient-enriched groundwater into rivers may contribute to eutrophication, and general ecosystem deterioration. Understanding of linkage between surface water and groundwater is thus critical for effective land and water resource management. Management of water resources in karst terrains is particularly critical because they occupy about 25% of the land surface and provide potable water to around a quarter of the world’s population, and approximately 40% of the potable water in the United States. Development or contamination of one commonly alters quantity and quality of the other. We used a mass balance approach based on distributions of naturally occurring radon isotope (222Rn) activity to determine the direction and magnitude of river water and ground water exchanges and their variations in space and time in the spring-fed Ichetucknee River in north-central Florida. This technique is newly developed for streams and our results show that the Ichetucknee River is a gaining stream, with contributions of groundwater to the river about 25-30% of the total river flow. Spatially, the lower section of the river, where the floodplain is wider, gains less groundwater than upper section. Groundwater flow to the river increase following the rain events because aquifer recharge within the karst catchment causes rapid groundwater head rise relative to the river stage and consequently enhances groundwater flow towards the river. Findings of this study provide information that will aid in the protection and restoration of hydrologic function and ecosystem services in stream environments. (Flesh-Kincaid Grade Level: 18.7)

10563

Soil organic carbon stock changes in the contiguous United States from 1920s to 2010s

Soil is a critical component of the total earth system. Climate is one of the most important factors of soil forming. Considering global issues of significance, such as food security, land degradation and global climate change, more emphasis is needed on maintaining soil’s natural condition by minimizing human-induced impacts and disturbances. It has been estimated that the total global soil C pool including wetlands and permafrost (3,250 Pg C) is about five times the biotic pool (650 Pg C) and about four times the atmospheric pool. Research on soil C has mainly focused on regional and local scales, while continental scale studies at a spatial resolution that matches underlying soil C variability is lacking. Anthropogenic induced decline in soil health and of individual components of soil quality, are a pressing ecological concern. To respond to threatens emerged in agriculture intensification, climate change and food security, place-specific strategies for sustainable land use using a whole-landscape, multisector perspective are needed. It is an interdisciplinary issue caused by current land use, demographics, and other biophysical and socioeconomic characteristics. This study, used large size dataset in the continental scale in a long-term, tries to explain the change trend of SOC over the time. Also, the important socio-economic issues were taken into account, by testing their effects on SOC temporal change. Therefore, this research is a preliminary study on a large scale research project which had linked natural resource, climate change and sustainable management. (Flesh-Kincaid Grade Level: 16.1)

10517

Modeling the Response of Soil Organic Matter Decomposition to Warming: Effects of Dynamical Enzyme Productivity and Nuanced Representation of Respiration

In this paper I am investigating the role of microbial processes in the production of greenhouse gases (i.e. carbon di-oxide, CO2 and methane, CH4) and how these processes are influenced by warming (temperature increase). The paper addressed the dynamics of soil microorganisms and enzymes (which catalyze biological reactions) produced by soil microbes and how that feeds back to soil organic matter decomposition (process by which organic substances are broken down into simpler forms). I critically scrutinized the formulations of the existing microbial and enzyme based soil organic matter decomposition models, especially how they deal with microbial carbon use efficiency, i.e. CUE (measurement of the ratio of carbon uptake by microbes for their growth per unit carbon decomposed). An alternate formulation of microbial respiration was incorporated into these models to counter both growth respiration (the amount of carbon respired toward microbial growth per unit carbon decomposed) and maintenance respiration (the amount of carbon respired toward maintenance of microbial metabolism per unit microbial biomass). I worked on the analytical solutions for these models under particular circumstances, and therefore was able to detect limitation and to work on improvements. Among other findings, I discovered that enzyme activity plays an important role to decomposition if its production is proportional to microbial biomass. Model results indicated that under warming, the decomposition of soil organic matter was more sensitive when the metabolic cost of enzyme production was higher. The findings suggested that microbial carbon use efficiency and thus rate of organic matter decomposition under warming were determined by the distinction of growth and maintenance respiration in microbes. (Flesh-Kincaid Grade Level: 16.7)

10431

Electronic Markets and Geographic Competition among Small, Local Firms

We study the impact of the Internet on small, boutique firms selling presence goods or services – goods or services which must be consumed in a specific location (for instance, a meal at a restaurant). These firms have recently begun to engage in electronic commerce, enabled by technologies and services such as location-aware advertising through mobile devices and local daily deal sites, such as Groupon and Living Social. Previous research regarding the interplay of local and Internet commerce has focused on larger companies selling similar products, such as Amazon competing with Barnes and Noble or Wal-Mart selling books or compact discs. We combine novel "big" data sets from Groupon, Flickr, Google Maps, and UrbanSpoon to examine the effects of lowered consumer search costs through brick-and-mortar vendors’ participation in electronic markets on local competition among restaurants and spas. We find that as vendors in a particular area participate in electronic markets (for instance, by offering a daily deal through Groupon), local competition increases and other vendors join the electronic market in response. This effect diminishes with distance. Further, we find that the impact on competition is moderated by the amount of differentiation of cuisine types and prices in a local area, with those areas having lower differentiation experiencing a higher competitive effect. Our findings validate theory in existing literature, and have implications for firms and daily deal platforms. (Flesh-Kincaid Grade Level: 18.2)

10421

Geochemistry and petrology of andesites from the north rift zone of Axial Seamount, Juan de Fuca Ridge

The majority of the earth's surface is covered by oceanic crust. Oceanic crust is generally composed of basalt, a volcanic rock type classified by its low silica (SiO2) content. A few locations on mid-ocean ridges, where oceanic crust is created, have rocks with higher silica compositions than basalts: how these high-silica volcanic rocks form at mid-ocean ridges is unknown and they are very rare. Last year, we sampled one of the largest exposures of high-silica rocks on a mid-ocean ridge. We collected andesites (a volcanic rock type with higher silica content than basalts) from a 4-km-long, 300-m-high cliff along the Juan de Fuca Ridge, a mid-ocean ridge in the Pacific Ocean off the coast of Oregon and Washington. We analyzed the chemical composition of the andesites and found they had also had high chlorine and water contents. The high chlorine and water contents are consistent with the composition of andesites collected from another mid-ocean ridge. Other geologists have recently proposed that oceanic crust can be altered by the hydrothermal system at a mid-ocean ridge, increasing the crust's chlorine and water contents and lowering its melting temperature, allowing the crust to melt and mix into an underlying magma chamber. That magma then erupts as lava flows on the sea floor, cooling to form the andesites we collected. We also analyzed the age of sediment samples we collected from near the rocks we sampled: we found the sediments, and thus the underlying rocks, were much younger than the age we predicted the crust should be in that location (<1,500 years old vs. >50,000 years old). Older crust is colder than younger crust so when the lavas erupted through older crust, the lavas cooled at greater rates than usual, which can increase their silica content. (Flesh-Kincaid Grade Level: 14.1)

10407

Communication Sciences and Disorders The ASHA Convention is the leading conference and meeting of scientists and professionals involved in speech, language, and hearing sciences. This annual event brings together over 12,000 attendees and presenters from across the world and offers more than 2,200 oral seminars and poster presentations. Within our Communication Sciences Masters Program at UF, we are encouraged to attend conferences and seminars to stay current with research so that we may better serve our patients with evidence-based practice and cutting edge procedures and interventions. Many of our faculty will be presenting oral and poster sessions. It is important to show my support as a current student who is involved in the research and work that we are doing here on campus, as well as a member of the UF community. In addition to attending the presentations of my colleagues and faculty, I am also interested in acquiring knowledge from experts of other topics and fields. I plan to network and create a dialogue with those who share my interests (e.g., dysphagia and aphasia) so that I may participate in intellectually stimulating conversations to increase my knowledge set while also promoting the research in which I am involved here at the University of Florida. The ASHA Convention is certain to be a rewarding experience and great aid in my professional development as I expand on my current knowledge and apply the lessons and recommendations that I gain to my future practice in this field.

My attendance to the 2014 ASHA Convention will benefit the student body and the greater UF community. The presence and visibility of UF faculty and students past and present is important in promoting our name and the involvement of the Gator Nation in speech and hearing sciences. This fits in well with our mission For the Gator Good. It is important to band together as the Gator Nation and demonstrate to others across the nation and world that we are determined to tackle tough issues and better our world. Being a research institution, this is especially important at research conferences and conventions. As a Gator involved in speech science research, I promise to promote our mission and research, participate in conversations, share treatment outcomes, and to open and join in dialogues about what else needs to be accomplished. My commitment to research in speech science and to the Gator Nation will be present and apparent when I attend the 2014 ASHA Convention and I hope to have the GSC's support.

10404

Error augmentation in chronic stroke: behavioral and neural correlates

After a person suffers a stroke, they have many deficits, including variability in force production. What our research aims to do is make people’s movement better following stroke. It has been shown that healthy people can improve movements when their error is exacerbated. For instance, a person can put thread in a needle easier if it is behind a magnifying glass. What is unknown is if post stroke individuals can alter movement with this method. To answer this question, we created an experiment in which a stroke individual was to produce force on a handle, and a cursor on a visual display would move according to the amount of force produced. We had “low” gains in which the cursor was very hard to move, and “high” gains in which the cursor would move greatly with small fluctuations in force. We found that stroke participants were able to perform better at the high gain compared to the low gain, agreeing with previous research in healthy controls. Additionally, we correlated the performance of each person’s performance with the integrity of regions in their brain. Regions that were correlated to performance were those that have previously been reported to be correlated with performance on motor tasks. At the high gain, where stroke participants performed best, a region named the PTR was found to be most strongly correlated. A complex analysis revealed that the PTR connects to essential vision and motor areas. As a result of this research, clinicians will be able use high gains in stroke participants to optimize performance in a motor task. Additionally, treatments can be focused on regions in the brain, such as the PTR. (Flesh-Kincaid Grade Level: 11.7)

10392

"APHA is a conference held annually in different cities within the United States to bring Public Health professionals as well as students together to share innovative research and findings within the public health arena. It is also a time in which students can gain an understanding of the profession and learn about new opportunities that are available for internship and life after graduation.

My attendance to the conference will aid me in fine tuning my ultimate goals after graduation. While my interest lies in vector-borne diseases and risk assessment there are times my concentration, environmental health, is hard to find relatable internship positions and studies in which to get involved with around campus. The conference will allow me to explore other ventures that are relatable in studying human health in relation to the natural and built environment.

During the conference I plan to attend the poster presentations relating to the environmental and global health concentrations. Specifically the talks on, “Environmental Justice: How health disparities are measured and addressed,” “Climate change vulnerabilities and impacts on human health,” and “The diverse issues of environmental health.” Other topics that are of interest to me are: “Why Neighborhood Matters in Assessing Environmental Health Risks, Public Health Intervention and Response to Improving Air and Water Quality, and Built environment: where you live, work and play affects your health.” I intend to speak with experts currently working for the federal government who are working at the Centers for Disease prevention and Control (CDC) in at the Environmental Protection Agency, in addition to those who are academically involved in research. I would like to get a first-hand account of the skills required to work in such institutions, in addition to measuring the skills I have obtained in the program and from my previous employment with the Department of Environmental Protection.

" The mission of the American Public Health Association is: “Improve the health of the public and achieve equity in health status.” As a master’s student, learning about the several components of public health, this conference will bring a collective understanding of the vastness and opportunities available to part-take in for internship and/or after graduation. As an officer of the Public Health Student Association here at UF, my travel will enable me to bring back valuable information to those who are unable to attend the conference. Additionally I will be able to disseminate information through my available outlets about opportunities that exist for students who are unsure about the future and what to do career wise in the coming years. Equally my involvement will provide me with a greater understanding and appreciation for the field, in turn making me a more efficient public health practitioner.

10390

3-D Crustal Velocity Structure of Central Idaho/ Eastern Oregon from Joint Inversion of Rayleigh Wave Group and Phase Velocities Derived from Ambient Seismic Noise: Newest Results from the IDOR Project

This research aims to provide the larger Geologic community with the seismic velocity structure (patterns of how fast seismic waves travel through earth material) of the sub-surface of the central Idaho and eastern Oregon region. I will present the latest velocity models at this meeting, which consist of 3-D color-coded velocity maps of the region's crust from the surface down to 50km depth. The data for these maps comes from 86 seismic sensors that myself and others deployed in this region between May 2011 and July 2013. I first processed the data by matching the signal pattern of a 24-hr period of seismic signal for a pair of sensor stations, and then averaging all available 24-hr periods of matched signals, or "stack", of that pair of stations in order to strengthen the signal-to-noise ratio. I made measurements on the "stacks" of how long Rayleigh waves (seismic surface waves) took to travel from the first to the second seismic sensor of each station pair in multiple frequencies of the seismic signal. I solved for 2-D velocity structure (how velocity changes horizontally, but not with depth) for each frequency that signal travel-times were measured. These maps were then processed to solve for the 3-D velocity structure (how velocity changes horizontally and with depth) of this approximately 200km north-south by 500km east-west region from the surface to about 50km depth (bottom of the Earth's crust in this region). Resolution tests of the resultant 3-D velocity structure show reliable horizontal resolution of changes in velocity of structures as small as 40km. Preliminary results show expected velocity structure based on the geology seen on the surface in the study region. We find higher seismic velocity in the western portion of the study region, and lower velocities in the deeper portions of the eastern end. (Flesh-Kincaid Grade Level: 15.8)

10383

Paper: Deficits in Executive Function as a predictor of lifetime drug use among African American women. Poster: The influence of illicit drug use on prosocial economic behaviors: implications for treatment.

"Paper:

African American female drug users are more likely than their male counterparts to exhibit problem solving difficulties. The present study investigates whether African American female drug users who have difficulties with problem solving have a higher risk of lifetime drug use.

Poster:

Participants whom self-reported the use of an illicit substance (confirmed by urinalysis) were recruited through street outreach and administered a standardized Behavior Interview.

Females were one as likely to be engaged in prosocial economic behaviors and almost twice as likely to be engaged in adverse economic behaviors illicit drug use mediates the relation between gender and adverse economic behaviors. Findings indicate that community residing female drug users may be at greater risk for adverse outcomes due to a greater engagement in inauspicious economic activities. Addressing ways in which individuals sustain themselves economically may improve treatment outcomes and it is necessary to attend to differential needs by gender.

(Flesh-Kincaid Grade Level: 16.7)"

10382

The mysteries of the super-generalist bark beetles (Scolytinae: Cryphalini: Hypothenemus).

The pygmy borers are tiny bark beetles which are found almost everywhere, living in the bark of trees, rotten twigs, living seeds, leaf stalks and vines of many different plants. Usually, one species feeds on one or just a few plant species. One group of bark beetles, Hypothenemus, is exceptional. Many of the species in the genus each feed on an extraordinary range of plants and plant materials. There are also some species which specialize on seeds, the most well-known being the coffee berry borer, which causes half a billion dollars worth of damage each year. There are even some species which have evolved farming fungi on wood for nutrition. Our preliminary analysis with the beetles morphology, which is now being coupled with large scale genetic information, suggests that the super generalist habit is old and probably coincided with the evolution their mating system. The fungus farming habit is likely to have evolved subsequently, and on multiple occasions within Hypothenemus. Another group within the genus specializes on heavily decayed tissue with a clear, but not understood, interaction with fungi. The diversity within Hypothenemus and other related bark beetles offer a unique opportunity in studying the shifts in ecological habits, and will unravel the secrets of some of the most widespread and abundant beetles in the world. (Flesh-Kincaid Grade Level: 14.2)

10379

From pavement to population genetics: Using citizen science data and ddRADseq to characterize the long-established pavement ant, Tetramorium caespitum, in North America

Pavement ants are the most commonly encountered ants in most cities in the Northern United States, yet we know little about their biology in urban environments or their introduction history. They are thought to have been introduced to North America in the early-to-mid-1800s and have since spread with humans as we’ve urbanized the continent. Because of this, they can serve as a model to understand how urbanization has spread introduced species in the past and how it influences relationships among populations today. Conveniently, pavement ants are also the most commonly collected species from the School of Ants citizen science project, and hundreds of collections of this species are available from all around the United States. So far, work I have done on this species utilizing citizen science collections has shown that they are found in more states than previously thought, that all are a single species originally from Europe, and that the protocol for the citizen science project – mailing us ants in a zip-lock bag that were frozen overnight – preserves DNA that is of sufficient quality for genetic work. By using a cutting-edge population genetic technique, I can answer a variety of questions about this species including: the number of mates a queen ant has to establish her colony, the number of times this species has been introduced to the United States, and whether populations in cities far away from one another in the U.S. are isolated or interacting with one another. These findings can help us better understand introduced species, ant biology, and the impacts of urbanization, and were made possible because of hundreds of people across the country interested in contributing to science. (Flesh-Kincaid Grade Level: 17.5)