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ECOLOGY OF SUBAERIAL ALGAE: PHOTOSYNTHETIC CAPACITY AS A FUNCTION OF RELATIVE HUMIDITY IN A NATURALLY- OCCURRING ASSOCIATION
No full textSubaerial algae are defined by their ability to grow on surfaces exposed directly to the air. We are currently investigating the nature of the adaptations that allow these unicellular microorganisms to form rich growths in an environment subjected to repeated and prolonged periods without liquid water. It is well known from laboratory studies that at least some members of the group are able to sustain metabolic activity using water vapor at high relative humidity. However, data concerning the significance of this ability in natural populations are almost completely lacking. To help fill in this gap, we tracked the photosynthetic capacity of a naturally-occurring association of subaerial algae over a period of 7 months using pulse-amplitude-modulated (PAM) fluorometry. The association formed a green film covering an area approximately 65 cm x 65 cm on a tiled porch on the campus of Valdosta State University. 20 measuring sites were selected, typically at the center of individual tiles. Baseline fluorescence (F’0), maximum fluorescence (F’m) and quantum yield (Y’) were measured at each site at 1 to 3 day intervals during the study period. A single measurement of relative humidity and air temperature about 1 cm above the surface was also made. Both F’0 and quantum yield showed a strong dependence on relative humidity. Below 70% RH, the value of F’0 remained low, typically less than 10% of the highest values recorded at each site, indicating the presence of photoprotective mechanisms activated in response to desiccation. Quantum yield was near background levels in this range. Above 70%, both F’0 and quantum yield increased with increasing RH. Linear regression of quantum yield vs. RH in this range suggests that significant photosynthetic activity begins at about 70% RH. The relative humidity met or exceeded this value at least 65 times during the study period
EFFECT OF TREMATODE METACERCARIAL INFECTION ON LOCOMOTION BY LARVAL SALAMANDERS IN NORTHEAST GEORGIA
No full textBecause many amphibians have suffered precipitous declines in recent decades, a great deal of research has been focused on the effects of emerging fungal and viral pathogens. However, relatively little attention has been given to the effects of macroparasites including trematodes, especially trematodes that do not produce obvious morphological abnormalities in their hosts. In the southern Appalachian Mountains of the US, a trematode currently assigned to the species Metagonimoides oregonensis, commonly utilizes lungless salamanders (Caudata: Plethodontidae) as second intermediate hosts, where metacercariae encyst within the musculature. The effects of this parasite have been presumed to be neutral because heavily infected salamanders survive. However, subtle impacts can be consequential to long-term physiological performance and survival. Metacercarial infections of the musculature in fish have been reported to negatively affect swimming performance; therefore, we tested the hypothesis that infection by this trematode species affects locomotor performance in aquatic larvae of the trematode’s primary second intermediate host, the Southern Black-bellied Salamander, Desmognathus amphileucus. We compared locomotion of a series of infected larvae, whose metacercarial cysts are easily seen through the translucent ventral wall of the trunk, with uninfected larvae by placing them in 1-m troughs of water and allowing them to move freely until they stopped. Our measured variable was time spent walking. Using non-parametric (Kaplan-Meier) survival analysis, we determined that infected salamanders stopped significantly sooner than uninfected ones (χ2 = 4.715, P = 0.299). Because infected salamanders move less, the presence of this parasite may contribute to genetic divergence in these salamanders by slowing dispersal and concomitant gene flow. Our results suggest that macroparasites can potentially have significant impacts on host biology even in the absence of such obvious effects as morphological abnormalities
NEAR INFRARED STUDY OF HYDRATION OF AQUEOUS HYDROXIDE **
No full textThe near infrared (NIR) and visible spectrum of the hydroxide anion (OH-) has been measured in aqueous solutions. We observe broad spectroscopic bands due to hydrogen-bonded water along with relatively narrow transitions due to hydroxide. All of the observed spectroscopic transitions are due to excitation of multiple quanta of O-H stretching vibrations. We have observed hydroxide stretching vibration transitions from 0 - 3 up to 0 - 6. Including data from previous infrared and Raman experiments yields the first determination of the spectroscopic constants, we, wexe and weye wfor the aqueous OH- anion. In careful measurements in the region of the 0-3 transition of aqueous OH-, we observe a new spectral transition that we attribute to the overtone spectrum of water molecules that are strongly hydrogen-bonded to the OH- anion. In further experiments, we have observed changes in this spectrum as a function of the OH- concentration, and we attribute the change in the spectrum to be due to changes in the number of water molecules that hydrogen bond to OH-, suggesting that the hydration number (n) of OH⁻(H₂O)ₙ is not constant but concentration-dependent. These results indicate that the hydration of OH⁻ ions in aqueous solutions are more complex than previously assumed, with implications for understanding solvation and ion-water interactions
LOCATING EXOPLANETS USING LIGHTKURVE**
No full textLightkurve software facilitates the analysis of time-series data of planets, stars, and galaxies collected by the Kepler and TESS space telescopes. Through the use of this software, as well as Python code, we can identify potential planetary transits from periodic dips in the brightness of stars. These periodic dips can be further refined and analyzed to determine other characteristics of the system such as the time of transit and approximate size of the planet. Data is gathered from the TESS space telescope using the MAST archive, and our research focuses on data from stars within about 20 lightyears from Earth. A variety of refinement techniques in Python are used to interpret and analyze this raw data. The lightkurve software and research like this expands our understanding of distant solar systems and provides an intuitive and user-friendly method of locating unidentified exoplanets. The specific star that I am analyzing is called TIC 283722336 and has about 0.8 times the mass of the Sun, located about 6.5 parsecs from Earth
IMPACT OF URBANIZATION, HABITAT STRUCTURE, AND FUNCTIONAL CONNECTIVITY ON SCAVENGER BEHAVIOR IN MOBILE COUNTY, ALABAMA AND CENTRAL GEORGIA**
No full textScavengers play a crucial role in ecosystems and urbanization introduces complex gradients in landscapes and their food availability. Our study explored scavenger behavior along a rural-to-urban gradient in Mobile County, Alabama and Central Georgia (CG) using trail cameras at bait stations. Data from Mobile County, collected from 2015-2017, served as pilot and comparison data for CG, which included counties south of Interstate 20 and north of Highway 280. We also evaluated how habitat structure, including the arrangement of plant communities and other physical features that affect habitat suitability, can impact scavenger behavior. Additionally, we examined how functional connectivity, which encompasses environmental elements like storm water systems and greenspaces that influence a population\u27s ability to move through the landscape to find food, shelter, and mates, affects scavenger behavior within levels of urbanization. We hypothesized that urbanization would affect scavenger behavior by: 1) Increasing the diversity of species acting as scavengers from rural to urban areas; 2) Changing the succession of species at bait sites across urban, suburban, and rural areas based, in part, on habitat structure; and 3) Influencing species composition based on functional connectivity within levels of urbanization. Preliminary data from Mobile County indicated that while species diversity was not significantly impacted, the succession of species at bait stations was. Avian scavengers (e.g., turkey vultures) arrived first in rural areas where habitat structures were more open, whereas small mammals (e.g., opossums, raccoons, domestic cats) arrived first in urban sites with less open spaces. Further investigation across more diverse sites is necessary. Geographic Information Systems (GIS) analyses were conducted to confirm urbanization levels and examine land connectivity. This research sought to deepen our understanding of ecosystem health and guide future studies on animal behavior and cognition
DATA AND DEBATES: LEGACY RADIOCARBON DATA IN SOUTH ASIA
No full textArchaeologists have long drawn on legacy radiocarbon data to develop chronologies and address research questions. However, this data is often dispersed across site reports, edited volumes, and journals from various countries, which makes it difficult for researchers to track down dates from older excavations. Moreover, legacy dates published before international standards were established sometimes lack complete contextual information including exact provenience, sample material, or processing techniques. As a result, using legacy data in archaeological research can be challenging. This paper presents the latest results of an ongoing and expanding legacy radiocarbon data project that examines patterns in radiocarbon dating over the past 70 years. The analysis reviews date densities in one region in South Asia and also assesses the contextual information published with those radiocarbon dates. The results demonstrate why some archaeological debates continue to be unresolved and they show which regions and time periods need more attention from archaeologists interested in radiocarbon dating. The analysis also enumerates the limits of the data and demonstrate why legacy radiocarbon data must be used carefully
UNIFIED STUDY OF THE CLASSICAL HALL EFFECT
Get PDFGermanium (Ge) samples with different doping types, acceptors (p-type) and donors (n-type), were studied to investigate charge carrier behavior. Carrier concentrations were found to be 1.16×10^21 m^(-3) for the p-type sample and 7.337×10^20 m^(-3) for the n-type sample. These experiments were conducted for the standard Hall effect (Hall voltage versus low magnetic field (B) values) as well as conductivity and Hall voltage versus temperature for different B-fields. The measurements versus temperature at zero-field allow us to obtain band gap ( Eg). While we investigate the conductivities for n-type and p-type doped samples, we also study the conductivity of an undoped Ge sample from which we obtained an energy gap of Eg=0.651eV which compares well with the known value of 0.67eV at room temperature. While it is commonly known that the classical Hall voltage is linear with B-fields, not so common is the behavior of the classical Hall voltage with temperature, especially for both n-type and p-type samples. Thus, we derive a general Hall voltage formula for semiconductors that unifies the understanding of both n-type and p-type carriers. Our experimental results are analyzed with the unified theory using MATLAB. An example MATLAB program is also included to perform calculations with our unified Hall voltage expression
BEHAVIORAL ECOLOGY AND DIETARY PREFERENCES OF GAMBUSIA AFFINIS IN A LABORATORY SETTING
No full textGambusia affinis, or mosquitofish, is an adaptable species found in freshwater and brackish environments, playing an important role in controlling mosquito larvae populations that transmit diseases. Parasitized mosquitofish with trematode infestations show visible dark spots, allowing us to categorize them as parasitized. These parasitized fish can have reproductive issues and altered mating behaviors making it crucial to investigate differences compared to healthy fish. Understanding the dietary preferences and behaviors of G. affinis is essential for its management as an environmental health indicator. Following the collection of mosquitofish from their natural habitats, experiments were conducted in a controlled laboratory setting to assess food preferences and behavioral differences in visually parasitized and non-parasitized G. affinis. The first study examined the food preferences of non-parasitized males, gravid non-parasitized females, and gravid parasitized females (n=10) across three food types: artificial pellets, live brine shrimp, and seaweed. Results showed a strong preference for live brine shrimp among all groups (p\u3c0.05). Secondly, we investigated how behaviors, such as swimming, freezing, thrashing, hiding, and eating, varied under different light conditions, such as daytime and nighttime simulations. Parasitized females (n=15) exhibited around 10.2 (±0.6) behaviors per minute during the day in white light, compared to 9.1 (±0.5) in red light simulating night. Non-parasitized females (n=15) under white light displayed about 7.3 (±0.6) behaviors per minute, while in red light they displayed 8.1 (±0.7). There was no statistical difference in behaviors across the red versus white light treatments for all female fish. These findings improve our understanding of the behavioral ecology of G. affinis and provide insights into their dietary preferences. As there are limited studies investigating mosquitofish, these results can later be compared to climate change models to determine if climate change is affecting mosquitofish populations
CONSTRUCTING A HANGING DROP OSMOMETER**
No full textWe designed an osmometer based on a hanging drop design by Weatherley (1960) for measuring osmolarities of small volume, botanical samples. An osmometer measures solute concentrations and can be used to indirectly quantify interactions between solutes. We constructed an osmometer prototype that we are displaying by the poster. It is constructed from gas-tight syringes, capillary tubing, and 3D printed supports. Changes in solution volume will be measured with a cell phone camera, magnifying lenses, and image analysis software. We are working to generate calibration curves for solutions of known osmolarity. Upon successful calibration of the osmometer, we will be able to measure interactions between osmolytes and native proteins and nucleic acids. Equivalent measurements have been limited in solute choice and concentration and temperature ranges by the constraints of commercially available osmometers. This instrument has the potential to permit measurements over a range of temperatures (through submerging the apparatus in a water bath or temperature-controlled chamber) and between solutes like osmolytes and lipid membranes—all things that are impossible with current, commercial instruments. These measurements of interactions between biological molecules will extend the power of predictive and analytical models used to help answer many biochemical questions
EXAMINING THE CRYSTALLINE STRUCTURE OF NANOCERIA
No full textMixed-valence cerium oxide nanoparticles (nanoceria) have gained significant attention due to their strong redox properties, which make them useful in a wide range of biomedical and industrial applications. However, the process of controlling the ratio of Ce3+ to Ce4+ in nanoceria, which is critical for many applications, is not well understood. In this ongoing study, nanoceria with specific Ce3+/Ce4+ ratios were created and extracted from a soluble borate glass by adjusting glass-melting parameters. The glass was heat treated to grow these nanocrystals and observe the crystalline structure. The extracted nanoceria were analyzed through XRD to determine the crystalline structures. Fourier Transform Infrared and Raman spectroscopies were used to observe the structure of both the nanoceria and nanoceria-embedded glass. Further, the Transmission Electron Spectroscopy was used to observe the lattice structures of the nanoceria with coexisting valence states