9th Annual Sigma Xi Student Research Conference
Wednesday, April 17, 2002
Georgian Lounge, Commons
Best Undergraduate Paper: PreZent: A Hierarchical Presentation Program using a Zoomable Interface Congratulations to this years winners
J. Chris Turner, Computer Science Student
Eugene Wallingford, Computer ScienceBest Graduate Paper: Growth Suppression Induced by Atrazine on Human Cells
Michelle Manske, Environmental Programs Graduate Student
Kavita R. Dhanwada, Biology
All Titles and Participants
Undergraduate Papers
PreZent: A Hierarchical Presentation Program using a Zoomable Interface
J. Chris Turner, Computer Science Student
Eugene Wallingford, Computer ScienceTesting the Feasibility of a Constant Speed Brushless DC Motor Controller
Chad Wunderlich, Industrial Technology Student
John Higby, Industrial Technology Student
Recayi Pecen, Industrial TechnologyPersistent Array Implementation using Berkeley DB
Matthew Lockner, Computer Science Student
Kevin O'Kane, Computer ScienceRemote global database access in Mumps
Michael Janssen, Computer Science Student
Kevin O'Kane, Computer ScienceRole of Titanium Dioxide in a Photocatalytic Degradation Reaction and in a Dye-Metal Oxide Reversible Metachromatic Phenomenon
Patrick A. Gibney, Biology/Chemistry Student
Shoshanna R. Coon, ChemistryTemporal Analysis of Nitrate and Phosphorus in Two Iowa Lakes
Sarah Wickman, Biology Student
Maureen E. Clayton, BiologyPredicted Effects of Confinement on the Melting Transition in Krypton-Argon Adlayers
Karson Bader, Physics Student
Michael W. Roth, PhysicsComputer Simulations of Planet Collisions using a New Parallel Algorithm
Wes Even, Physics Student
Michael W. Roth, PhysicsHydrologic Contaminant Transport Modeling Suited for Undergraduates: A Novel Analytical and Computational Approach
Cody M. Wilson, Physics Student
Michael W. Roth, Physics
Mohammad Z. Iqbal, Earth ScienceComputational Modeling of Pool Games: Sensitivity of Outcomes to Initial Conditions
Christian Leerberg, Biology Student
Michael W. Roth, PhysicsVertical Distribution of Available Phosphorus in the Bottom Sediments of a Biologically Inactive Lake
Chad L. Fields, Earth Science Student
Arianna N. Houge, Biology Student
Heather J. Bailey, Earth Science Student
Mohammed Z. Iqbal, Earth Science
Edward J. Brown, BiologyCorrelations among nutrient levels, bacterial numbers, and other developmental factors with mosquito production from Iowa lakes: results of a three-year study
Sara L. Sheeley, Biology Student
Rhiannon L. Huffman, Biology Student
Brad M. Woodle, Biology Student
Sarah A. Hansvick, Biology Student
Christopher J. Dickerson, Biology Graduate Student
Holly T. Bignall, Biology Student
Melissa L. Stoll, Biology Student
David R. Mercer, BiologyNon-Contact Measurement of the Viscosity of Binary Fluids
Justin Smith, Physics Student
Fred Behroozi, PhysicsTolerance of summer nocturnal frost by leaves of Potentilla gracilis
Kerry Bohl, Biology Student
Virginia Berg, Biology
Robert Wise, University of Wisconsin - Oshkosh
Graduate Student Papers
Health Promotion Evaluation and Needs Assessment in the Transylvania Region of Romania
Bryan Byrd, Environmental Programs Graduate Student
Diane Depken, HPELS
Catherine Zeman, HPELSField Methodology for the Determination of the Prevalence of Giardia Cysts and Cryptosporidium Oocysts in Drinking Water and its Association to the Development of Diarrheal Disease in the Transylvania Region of Romania
Rick Bauer, Environmental Programs Graduate Student
Catherine Zeman, HPELS
Mariana Vlad, Institute of Public Health, Cluj-Napoca, RomaniaAlcohol-related Behavior in the Adult Population: A Daily Diary Approach
Danielle L. Johnson, Health Education Graduate Student
Joseph G. Grzywacy, HPELS
Amanda K. Hartwig, Health Promotion Student
David M. Almedia, Division of Child and Famiy Studies, University of ArizonaGrowth Suppression Induced by Atrazine on Human Cells
Michelle Manske, Environmental Programs Graduate Student
Kavita R. Dhanwada, BiologyRefactoring Software Using Patterns: An Approach to Improving the Quality of Software
Masatomo Noborikawa, Computer Science Graduate Student
Eugene Wallingford, Computer ScienceQuaternary Stratigraphy and Soil Geomorphology of the Lower Little Cedar River Valley, Northeast Iowa.
Dale K. Splinter, Geography Graduate Student
Dennis E. Dahms, Geography
Dave W. May, GeographyEnvironmental Factors Affecting Arsenic Contamination of Ground Water in Bangladesh
Karla L. Suckling, Geography Graduate StudentDevelopment and validation of the Sport Toughness Scale
Susan E. Stoker, HPELS Graduate Student
Pedro A.M. Zogaib, HPELS Graduate Student
Health Promotion Evaluation and Needs Assessment in the Transylvania Region of Romania Abstracts
Bryan Byrd – Environmental Programs
Diane Depken – HPELS
Catherine Zeman -- HPELSSince the revolution of 1989, Romania has been undergoing wide-ranging changes affecting all aspects of the country including health promotion. As common to many newly independent states (NIS) the changes in socio-economics, on-going poverty, unemployment status, and the overall culture shock of political transition, has resulted in health characteristics and indicators improving in some areas but suffering in others. This project was initiated as a descriptive study of the health promotion practices of Transylvania, Romania. The goal of the research was to describe and discover the philosophical practices driving current Romanian health promotion practices, as well as to conduct a needs assessment. Thirty-eight health professionals were interviewed with a 35-question survey, then immediately followed up with focus group discussion. In addition to the health professional survey and discussion, villages across Transylvania were visited and 70 Romanian citizens were interviewed regarding their perceptions concerning the current health promotion practices. Knowledge and awareness concerning the topic of Methemoglobinemia was also of interest as some of the participants were identified, through a related study in this region, as having had experienced the disease. It was discovered that there are national programs established by law for health promotion in Romania, but allocation of funding for those programs is limited, resulting in many needs remaining unmet across the country. Insufficient labor and funding were found to be of highest concern to the health professionals surveyed. Also, difficulty in reaching rural populations was a problem.
Current health promotion activities practiced by local health professionals were discovered to focus on the individual as the instrument of responsibility in regards to health. Other implicating factors, at the societal, political, or ecological levels were not recognized by the Romanian health professionals and were not brought up during focus group sessions. It was concluded that the health promotion practices most resemble the constructs of the Health Belief Model, with an emphasis on the individual’s responsibility for their own health. For health promotion practices to improve, future expansion of focus to other factors impacting health is suggested. If programs and health behavior are to improve, consideration of influential factors that include the environment, interpersonal relationships, and community change is needed.
Field Methodology for the Determination of the Prevalence of Giardia Cysts and Cryptosporidium Oocysts in Drinking Water and its Association to the Development of Diarrheal Disease in the Transylvania Region of Romania
Rick Bauer, Environmental Programs
Catherine Zeman, HPELS
Mariana Vlad, Institute of Public Health, Cluj-Napoca, RomaniaThe purpose of this study was to analyze the drinking water of 69 individuals living in the Transylvania region of Romania for the presence of Giardia cysts and Cryptosporidium oocysts. The ultimate objective was to determine if a correlation exists between the presence and concentrations of these two protozoa and the reported frequency and average severity of diarrheal disease in the study group members.
To accomplish this goal, a collection, emulsion, concentration, labeling, and identification method had to be developed that could operate effectively in an international field setting. The protocol selected included the collection of samples using a compressed foam filter cartridge, emulsion and concentration using a commercially supplied wash station, labeling of cysts and oocysts utilizing an indirect immunofluorescence assay, and inspection using an epifluorescent microscope. A questionnaire was administered to determine the frequency and severity of diarrheal disease in study group members.
Of those water sources tested, 27 (39%) were found to be positive for Cryptosporidium oocysts, and 30 (43%) positive for Giardia cysts, with seventeen wells (25%) testing positive for both. Statistical analysis indicates a correlation between the presence of Cryptosporidium oocysts and the frequency of diarrheal disease (Likelihood Ratio, ChiSquare = 14.301, p = 0.0064), and the presence of Giardia cysts and the severity of diarrheal disease (Likelihood Ratio, ChiSquare = 12.157, p = 0.0327). ANOVA analysis of the relationship between Cryptosporidium oocyst and Giardia cyst concentrations and the reported frequency of diarrheal disease indicates a significant correlation between the frequency of diarrheal disease and the concentration of Cryptosporidium oocysts (ANOVA, f-ratio = 4.3277, p = 0.0037) and Giardia cysts (ANOVA, f-ratio = 5.9876, p = 0.0004). A correlation between Cryptosporidium oocyst and Giardia cyst concentrations and average severity of diarrheal disease was also detected, Giardia cyst concentrations (ANOVA, f-ratio = 13.4211, p = 0.0005) and Cryptosporidium oocyst concentrations (ANOVA, f-ratio = 5.3926, p = 0.0233).
The prevalence of Cryptosporidium oocysts and Giardia cysts in the wells sampled in this study represents a potential health risk for the very young and immunosuppressed individuals living in the rural areas and small villages of the Transylvania region of Romania.
Alcohol-related Behavior in the Adult Population: A Daily Diary Approach
D.L. Johnson, Health Education, HPELS
J.G. Grzywacy, HPELS
A.K. Hartwig, Health Promotion, HPELS
D.M. Almedia- Division of Child and Famiy Studies, University of Arizona, Tucson, AZObjectives. Researchers are frequently concerned with the accuracy of retrospective reports of alcohol consumption, thus the purpose of this study was to examine the prevalence of several alcohol-related behaviors, including binge drinking, in the adult population using daily reports of consumption.
Methods. Any alcohol use, frequency of alcohol use, and incidence of binge drinking were constructed from daily reports of alcohol consumption obtained through daily telephone interviews as part of the National Study of Daily Experiences (NSDE; n= 1,031). Differences in the alcohol-related behaviors were examined by age, gender, race, education, income, marital status and parental status.
Results. 43.7% of adults drank during the interview period, and 11.8 % of adults binge drank one or more times. Male gender, along with a higher level of education and household earnings were associated with greater likelihood of drinking during the interview period. Age was the only demographic characteristic associated with binge drinking. A clear, inverse monotonic relationship was found between age and binge drinking (c2 = 16.3; df = 4; p < .01).
Conclusions. During any given week of the year one in ten adults engage in binge drinking, and age was the only demographic predictor of binge drinking. The absence of other differences in binge drinking by demographic characteristics suggests that common observations of difference may be attributed to inaccurate or biased recall.
Growth Suppression Induced by Atrazine on Human Cells
Michelle Manske, Environmental Programs
Kavita R. Dhanwada, Department of BiologyThere is increasing concern that certain chemicals in the environment can lead to contamination of ground water and soil. One commonly used chemical that raises environmental concern is the herbicide atrazine (2-chloro-4-ethylamine-6- isoprpylamino-S-triazine). Atrazine is a chlorinated triazine herbicide used to control annual grasses and broadleaf weeds in crops. Due to the widespread use of herbicides in agriculture in the Midwestern states, atrazine has entered surface and groundwater supplies. Because of the potential for human exposure, the EPA has established a maximum contaminant level (MCL) of 3 ug/L (3 ppb) for atrazine. However, recent studies of prolonged atrazine exposure in several cell types have shown that even levels below MCL amount can lead to increased cellular DNA damage, reproductive problems and cancer.
The objectives of our research are to look at the effects of low-level exposure of atrazine on normal human fibroblast cells in culture. We have seen that low-level short-term exposure of atrazine to the fibroblasts results in decreases cell proliferation. In saturation density studies, we have shown a decrease in the cell number in a dose dependent manner. We also see a decrease in cell proliferation by MTT (3-(4,5-dimthylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide dye) assays. Preliminary studies to look for apoptosis/DNA damage in cells exposed to atrazine using immunohistochemical analysis has shown that atrazine may contribute to DNA fragmentation. By examining cells exposed to environmentally relevant levels of atrazine, we hope to better understand the possible effects of atrazine on the cell cycle.
Refactoring Software Using Patterns: An Approach to Improving the Quality of Software
Masatomo Noborikawa, Department of Computer Science
Eugene Wallingford, Department of Computer ScienceDesigning a software system prior to implementation often results in designs that are incomplete or incorrect. Creating a good design is difficult because it is hard for the designer to know everything he needs to know about the solution before writing the program. Often, the programmer must correct mistakes in the design as he comes to understand the problem and solution better while writing the program.
Even when the programmer comes to know that something is not right in the design, it is often hard to know where or how to correct it. The process of "refactoring" guides the programmer as he identifies weaknesses in the design and code and methods to improve them. We are investigating the use of design patterns as a means to trigger modifications to designs and programs that preserve the functionality of the system while improving the quality of the software. This approach offers a powerful set of tools for programmers to use as they evolve their designs throughout the writing of a program.
PreZent: A Hierarchical Presentation Program using a Zoomable Interface
J. Chris Turner, Computer Science
Eugene Wallingford, Computer ScienceCommonly found presentation software use an inefficient linear method for conveying information. The audience is unnecessarily forced to group the data into logical segments when the software fails to provide the hierarchy required. Utilizing a zoomable interface, PreZent allows for hierarchical data visualization. This tool takes advantage of the brain's natural grouping of information to increase audience retention.
Testing he Feasibility of a Constant Speed Brushless DC Motor Controller
Chad Wunderlich, John Higby, Industrial Technology
Dr. Recayi Pecen, Industrial Technology
Sponsor: Viking Pump, IncDC brushless motors can be coupled to pumps directly to create a seal-less design. This setup is useful for transporting liquids that are difficult to contain with conventional seals or hazardous liquids. An inherent problem with this setup is maintaining a constant motor speed; brushless DC motors slow in speed at increasing loads. Because pump output is proportional to motor speed, changes in fluid viscosity and pressure result in changes in pump capacity. We will be designing and testing a motor controller consisting of a micro-controller, DC servo amplifier, and input and output interfacing circuit. One potential application for this new technology is to maintain a steady motor speed in a pump-motor combination. Our project is to test the feasibility of this controller using fractional horsepower motors and pumps. Results from the tests will be provided to Viking Pump as a starting point for future development.
Quaternary Stratigraphy and Soil Geomorphology of the Lower Little Cedar River Valley, Northeast Iowa.
D. K. Splinter, D. E. Dahms, & D. W. May, GeographyLittle information exists about the Late-Wisconsin and Holocene alluvial stratigraphy for the landform region known as the Iowan Surface. For this reason, we investigated the Late-Wisconsin and Holocene alluvial stratigraphy along the lower Little Cedar River in order to understand the ages and the geomorphic locations among the landforms within this valley of northeast Iowa at Nashua. We used terrace tread height above the Little Cedar River and relative soil development to distinguish among alluvial units.
At least two Pleistocene (Late-Wisconsin) alluvial surfaces are present in the valley. One of these is a footslope surface that interfingers with a Wisconsinan-aged alluvial fill. The other is a higher fill terrace. Holocene alluvial units present here include three terraces and the modern floodplain. Elsewhere in the Midwest, these units have been described as the DeForest Formation. This Formation contains the Camp Creek, Roberts Creek, and Gunder Members. An additional unit called the Late Roberts Creek was also identified in this study.
Soil textures throughout the Little Cedar River Valley range from clay loam and loam to sandy loam. Late-Wisconsin soil profiles consist of A/Bt/C or A/Bw/C horizon sequences. Evidence for major period(s) of erosion is present within late-Wisconsin deposits in the Lower Little Cedar River Valley. These include stone lines overlying different sedimentological deposits, which are found at different heights in the valley. These stratigraphic indicators are used to support the possibility of two separate periods of erosion prior to the Holocene.
The most developed Holocene alluvial soils are found within the Gunder Member. Profiles include either A/Bt/C or A/Bw/C horizonation. Soils in Roberts Creek alluvium are not as developed as those in the Gunder Member. These profiles are predominately A/Bw/C. A radiocarbon age of 460 ± 50 on an Elm log in the youngest Roberts Creek Member supports the soil development of this unit. Soil development within Camp Creek alluvium is minimal and soils consists of A/C profiles.
Environmental Factors Affecting Arsenic Contamination of Ground Water in Bangladesh
Karla L. Suckling, GeographyBangladesh has the world’s most severe groundwater contamination problem involving arsenic. The arsenic that is contaminating tube-wells across Bangladesh is naturally occurring and its concentration varies drastically over short distances. The World Health Organization advises that arsenic levels in drinking water be maintained below 10 parts per billion and the national recommendations (standards have yet to be established) for Bangladesh are less than 50 parts per billion. Samples collected by the British Geological Survey have shown many arsenic levels at more than 50 parts per billion. The sampling covers approximately 129,000 km2 out of the 152,000 km2 of land in Bangladesh. According to various sources an estimated 16 to 70 million people may be at risk of drinking arsenic contaminated water. The purpose of this research is to describe areas with groundwater high in arsenic content and to associate arsenic concentrations with different environmental variables. The environmental variables include tube-well depth, physiography, and flood land type. Data for this study has been acquired from the British Geological Survey and a geographic information system database that was created using a variety of socio-environmental sources. The results of this analysis will include identifying specific tube-well depths, physiographic units, and flood type levels that correlate with ground water arsenic levels above 50 parts per billion.
Persistent Array Implementation using Berkeley DB
Matthew Lockner, Computer Science
Kevin C. O'Kane, Computer SciencePersistent arrays, that is, arrays that retain their contents between program invocations, can be viewed as an abstract data type intuitively implemented into a programming language using a simple database facility and secondary storage. Mumps is a simple language with a BASIC-like, line-oriented syntax, used in the computer science department's information storage and retrieval classes. The Mumps language has an intrinsic persistent ("global") array data type whose usage is similar to an ordinary array reference in common programming languages. This feature proves useful in creating large-scale document processing applications, and any application requiring data persistence with intermittent computation upon or update of that data. Moving the feature into the language level makes the design of such applications shorter and more succinct than the equivalent in most mainstream languages.
This presentation discusses the implementation of the Mumps global array type in a free multiplatform compiler, using the open source database product Berkeley DB to support the implementation of the global array operations. Berkeley DB is a robust, non-relational database layer whose functionality matches very well with our intended array implementation. The end product is an agent serving as an intermediary, translating requests for Mumps global array services into requests for Berkeley DB services. We discuss design and implementation issues, and an evaluation of the software versus the previous implementation within the compiler. Presentation of relevant applications currently in use will be included, and the types of general problems well suited toward solution using these techniques. We include ideas for future work and possible improvements upon the existing work.
Remote global database access in Mumps
Michael Janssen, Computer Science
Kevin O'Kane, Computer ScienceAccess to global data in applications has been a focus of computer science for years and has developed into a new field of study. Mumps is a language which smoothly and seamlessly integrates global database accesses into it's syntax. Using a global database which was not located locally was previously not an available non-commercially. Multiple possible implementations that would facilitate accessing a Mumps global database over a network are discussed, along with advantages and disadvantages of each. One complete implementation is presented, and the implementation's structure and protocol are discussed. Issues of security of data while in transmission as well as reliability and speed are addressed. Future goals, including replication of databases to multiple machines and possible changes to the protocol for more efficient operation are also discussed.
Role of Titanium Dioxide in a Photocatalytic Degradation Reaction and in a Dye-Metal Oxide Reversible Metachromatic Phenomenon
Patrick A. Gibney, Chemistry
Shoshanna R. Coon, ChemistryThe goal of this research was to study the role of titanium dioxide, a semiconductor metal oxide, in two types of reactions. In photocatalytic degradation of Crystal Violet, it was already known that titanium dioxide acts as a photocatalyst. We focused our interest on the possibility of intermediates or products of the photodegradation reaction being either in solution or adsorbed onto the titanium dioxide. We found that the Crystal Violet was completely degraded, according to UV-Vis spectra, after approximately 1 hour in direct sunlight. We also found that there is a possible intermediate or product that adsorbs onto the titanium dioxide surface that absorbs light in the visible light region. Interestingly, an unknown and irreversible reaction between titanium dioxide and water was discovered to form a product that adsorbed onto the titanium dioxide.
In a metachromatic phenomenon involving an Azure B/Titanium dioxide slurry, the titanium dioxide surface adsorbs varying amounts of water, which causes dye monomers, dimers, and other aggregates to form. These aggregates have different absorbance spectra, and therefore cause color changes. In addition, other metal oxides showed some ability to act as a substrate for reversible metachromasy of Azure B as well.
Temporal Analysis of Nitrate and Phosphorus in Two Iowa Lakes
Sarah Wickman, Biology
Maureen E. Clayton, BiologySilver Lake, a small Iowa impoundment lake, does not currently meet the designated uses of recreational fishing and swimming. One potential cause of noncompliance is eutrophication. Healthy lakes are dependent upon moderate inputs from surrounding watersheds; however, excessive nutrients upset the balance between production and decomposition of biomass. Agricultural lands are often highly erodible, and are major sources of sediment, fertilizers, and pesticides to receiving water bodies, including lakes. Excessive production of biomass due to increased nutrient inputs overwhelms the capacity of the lake to process dead biomass into harmless degradation products, and leads to oxygen depletion in lakewater. In severe cases, such as that of Silver Lake, fish and other desired species die, and are replaced by harmful algae and bacteria, insects, and other plants and animals adapted to surviving in waters with low oxygen and high turbidity. Nitrate and phosphorus levels were monitored in Silver Lake and the control site, Casey Lake, over 3 years to determine the temporal trends of nutrient enrichment in these watersheds.
Development and validation of the Sport Toughness Scale
Susan E. Stoker, HPELS
Pedro A.M. Zogaib, HPELSThe purpose of the present study was to construct and validate the Sport Toughness Scale; an instrument designed to measure the mental, emotional, and physical toughness skills of athletes. Based on a review of literature, 85 items were constructed to measure 6 different conceptual constructs of toughness concentration, ideal performance state, rebounding ability, self-control, coping with pressure, and self-directed). Preliminary data was obtained from a sample of 39 students enrolled in a physical education college course. Item-total analyses indicated that 20 items should be removed. Exploratory factor analysis of the remaining 65 items revealed 18 components accounting for 87.3% of the total variance. In summary, preliminary data is positive and suggests that additional research is warranted.
Predicted Effects of Confinement on the Melting Transition in Krypton-Argon Adlayers
K. Bader, Physics
M.W. Roth, PhysicsWe report the results of (N,rho,T) Molecular-Dynamics computer simulations of krypton-argon mixtures physisorbed between two graphite sheets. Three novel aspects of the system's behavior emerge from this study. To begin with, new high-temperature commensurate solid phases for both argon and krypton as a result of confinement are predicted, as well as a family of confinement-induced solid-liquid phase transitions. In addition, we observe that the melting temperature of the system can be adjusted within a given range by the graphite sheet spacing. Finally, in the case of argon-krypton mixtures, certain temperatures and sheet spacings result in almost complete impurity extraction.
Computer Simulations of Planet Collisions using a New Parallel Algorithm
W. Even, Physics
M.W. Roth, PhysicsWe report the results of new deterministic computer simulations of planets colliding. We find that for various initial conditions the system may clump together forming a new object or may rotate, causing ejecta to leave the primary mass in a pattern sustaining only a short number of orbits, but promising of satellite formation. The results of collisions between planets of various construction are discussed . We also mention the results of a rudimentary scaling study when the code is parallelized using a force-decomposition scheme and we make recommendations for future work.
Hydrologic Contaminant Transport Modeling Suited for Undergraduates: A Novel Analytical and Computational Approach
C.M. Wilson, Physics
M.W. Roth, Physics
M.Z. Iqbal, Earth ScienceWe have developed a method for modeling contaminant transport in aquifers with rectangular boundaries utilizing an analytical solution to the porous medium flow equation and a finite difference solution to the advection-dispersion equation. Any number of wells may be placed within the aquifer, as well as any number of non-interacting contaminants. Constant head boundaries which simulate rivers may be included by means of a source term. With realistic parameters we are able to successfully model and predict contamination transport in an on-campus well site used for both undergraduate pedagogy and research.
Computational Modeling of Pool Games: Sensitivity of Outcomes to Initial Conditions
Christian Leerberg, Physics
M.W. Roth, PhysicsThe focus of this study is to learn about the sensitivity of outcomes of a pool break based on very small changes in the initial conditions prior to the break. Variables include cue ball initial velocity and position on the “table”. Also, the trajectory of a single ball was examined while it moved through the table space. We find scale invariance over a wide range of parameters. In addition we find that a single ball may be locked in repeating four- or two-cycles which experience large sensitivity to initial conditions.
Vertical Distribution of Available Phosphorus in the Bottom Sediments of a Biologically Inactive Lake
Chad L. Fields, Earth Science
Arianna N. Houge, Biology
Heather J. Bailey, Earth Science
Mohammed Z. Iqbal, Earth Science
Edward J. Brown, BiologyLake watersheds often play a crucial role in phosphorous (P) cycling between the biosphere and the hydrosphere. P arrives in natural aquatic ecosystems as a consequence of agricultural land use. Soil runoff P does not have an escape route to the atmosphere. It accumulates and stays in the bottom sediments, thereby damaging the ecosystem.
In June 2001, sediment cores were taken from 15 spots in Silver Lake of northeast Iowa. Unwanted algal bloom characterizes the lake in late summer, which lowers the dissolved oxygen content in water (< 2.0 mg/L). Currently, the lake does not support its designated uses for recreational purpose. The average P concentration in the top 2 inches of sediment is 630 mg/gm (range: 11 mg/gm to 1.3 mg/gm). In 10 of these spots (66%), P concentration exceeds 600 mg/gm. In 11 of these cores (73%), a strong concentration gradient is observed with P decreasing vertically downward. At these 11 spots, average P concentrations are 848 mg/gm at 0-2 inch, 666 mg/gm at 4-6 inch, and 420 mg/gm at 8-10 inch. Further examining 8 deep cores, the average P concentration at 12-14 inch depth was calculated as 293 mg/gm. It is evident from the above results that sediments in Silver Lake are heavily contaminated with soil runoff P. The vertical gradient indicates that sediment contamination has increased in recent years, which dramatically restricted biological activities in the lake. It seems that any strategy for restoring Silver Lake should include dredging the sediments.
Correlations among nutrient levels, bacterial numbers, and other developmental factors with mosquito production from Iowa lakes: results of a three-year study
Sara L. Sheeley, Biology
Rhiannon L. Huffman, Biology
Brad M. Woodle, Biology
Sarah A. Hansvick, Biology
Christopher J. Dickerson, Biology
Holly T. Bignall, Biology
Melissa L. Stoll, Biology
David R. Mercer, BiologyNutrient inputs into a lake may influence mosquito production. Both types and numbers of mosquitoes produced from a lake may influence local mosquito-borne disease transmission. During three summers (1999-2001), mosquito abundances and possible developmental factors were measured in nutrient-impacted Silver Lake (Delaware County) and in relatively unpolluted Casey Lake (Tama County) to investigate whether nutrient inputs influenced mosquito production from these lakes.
Developmental factors included water pH, temperature, electrical conductivity (EC), total alkalinity, insect predators, and rainfall within the watershed. Concentrations of nitrate, nitrite, phosphorus, protein, and bacteria were also estimated. Insects were counted weekly in five 375 mL dip samples at each of 33 (Casey Lake) and 27 (Silver Lake) sites around the lakes’ perimeters. Temperature, EC and pH were measured with portable meters 4 cm below the water surface, and nitrate, nitrate, total alkalinity and phosphorus were measured with chemical test strips. Water samples were retained from each site for protein and total plate count agar bacterial estimates. Rainfall data were obtained from the State Climatologist Office, monthly Iowa Climate Review. For each factor investigated, weekly means were calculated for each lake and used to determine which developmental factors correlated significantly with mosquito production.
Many significant correlations were found among factors at each lake, but few patterns were consistent throughout the three-year study. In Casey Lake, predator numbers increased during each summer, and for 1999 and 2001, predator numbers also correlated significantly with pH. In Silver Lake, predators increased during 1999 and 2000, but not in 2001. During 2000, mosquito numbers increased over time and were positively correlated with total alkalinity and bacteria, but also with predator numbers. Furthermore, in 2001, Silver Lake mosquitoes were positively correlated with nitrite, and bacteria decreased with time. We investigated a multiple regression model of mosquito production using these developmental factors in an attempt to estimate variation in mosquito production.
Non-Contact Measurement of the Viscosity of Binary Fluids
Justin Smith, Physics
Fred Behroozi, PhysicsWe have measured the kinematic viscosity of a binary mixture using a novel technique based on laser interferometry and the attenuation of capillary-gravity waves. This method provides a non-contact method for measuring the viscosity of fluids. We present data on the glycerol-water binary system as a test case, with glycerol concentrations ranging from 5%-80%, at controlled temperatures. The results are compared to published data obtained through traditional flow viscometry.
Tolerance of Summer Nocturnal Frost by Leaves of Potentilla gracilis
Kerry Bohl, Biology
Virginia Berg, Biology
Robert Wise, University of Wisconsin - OshkoshPlants in temperate alpine zones can experience large diurnal changes in temperature, ranging between -5°C and 25°C at 3000 m in the mountains of Wyoming, USA. Leaves of several species become brittle and coated with ice crystals at night throughout the growing season. We determined the role of chilling in acclimation to frost, and the changes in cell shape associated with lethal and sublethal frost. In the laboratory, excised leaves of growing plants were subjected to temperatures from 0 to -15°C for 10h. Control plants were compared with plants chilled at 4°C for at least 3 nights prior to cold treatment, and damage was assessed based on leaf appearance. Water uptake through the petiole was compared for plants exposed to cold temperatures (-4 to -8°C) and controls held at 20°C. Changes in cell shape and intercellular spaces among control plants, plants that recovered from the frost treatment, and those that did not survive were determined using scanning electron microscopy of liquid N2-frozen fresh samples. All leaves survived at 0°C and died at -15°C, indicating that even prechilled plants had limited cold tolerance. Leaves below approx. -4°C were brittle. Prechilling conferred approximately 4°C of additional frost tolerance (LT50=-8.5°C for prechilled plants). Leaves at room and freezing temperatures did not differ in water uptake. Mesophyll cells exhibited reduced volume following freezing treatment. Cells shrank substantially at temperatures near -10°C, which is colder than field temperatures; these leaves died upon rewarming. At higher temperatures (near -5°C), cells shrank slightly, then regained volume the next day, recovering fully. Chilling temperatures experienced nightly by these plants confers the freezing tolerance necessary to survive the coldest nights, near -5 °C.