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FLOW OF ENERGY AND MATTER IN ECOSYSTEMS: THE ROOTS OF A MISCONCEPTION
No full textThis paper reveals the roots of one of the most persistent science misconceptions regarding the flow of energy and matter in ecosystems. The misconception that the O2 released during photosynthesis originates from the CO2 absorbed is rooted in the intuitive beliefs of R. Feynman, a Nobel Prize laureate. Feynman (1988) stated that, the sun is doing the work of separating the oxygen away from the carbon, and pushing the oxygen away from the carbon. The scientific consensus is that during photosynthesis, the oxygen released is actually derived from the water molecules, not the carbon dioxide. Feynman\u27s Nobel Prize led some media outlets to erroneously conflate his authority in physics with expertise in science education teaching and promoted the misconception via supporting Feynman\u27s statements that amount to pseudoscience. Consequently, the misconception was implemented as a benchmark in Atlas, Project 2061, a trusted national educational resource (AAAS, 2001). Said and Martin-Hansen (2019) presented evidence that the 9-12 benchmark, Plants alter earth\u27s atmosphere by removing carbon dioxide from it, using the carbon to make sugars and releasing oxygen hamper students\u27 understanding of the flow of oxygen and carbon dioxide in ecosystems. Currently, the Atlas\u27 benchmarks are adopted in many educational districts, and are taught in many high schools nationwide. As the 9-12 misconceptions are left unchallenged, they\u27re carried onwards to universities, to those who pursue science education and become pre-service, and graduate as science teachers themselves. This paper attempts to disrupt this cycle, suggesting simple, clear, and correct K-12 lesson plans to clarify the flow of energy and matter during photosynthesis. The paper suggests that teaching the history of the misconception is used as a vehicle for overcoming such pseudoscience and encouraging the role of students as active participants in the learning process
MODELING THE ORBITAL DYNAMICS OF SUPER EARTH KEPLER-62F
No full textNASA\u27s Kepler mission to survey a portion of the Milky Way Galaxy for exoplanets was a resounding success, giving us over 2,600 exoplanets to study. Kepler-62f is one planet discovered from this mission on a shortlist for possible habitability, as it orbits within the habitable zone of its host star. Therefore, there is a possibility for water to exist on the surface of the planet. We have simulated the orbital dynamics of Kepler-62f around its host star using Jupyter notebook and Rebound. Rebound offers visualization capabilities for simulation results, making it easier to evaluate complex orbital dynamics. Data gathered and assumptions made on the Kepler-62 system from previous studies and our created simulations may give us further insight into the orbital nature and possible habitability of the system. The result of this study was visual data of the star system\u27s state after a couple hundred thousand years, with the effects of Kepler-62f\u27s orbit on the other planetary bodies in the system and vice versa. Studying and simulating the orbital dynamics of Kepler-62f could help us understand how other possibly habitable exoplanets orbit around their stars. Further studies of this and other star systems may lead to insights on how orbital dynamics of exoplanets affect climate and potential habitability
MASS DERIVATION OF PLANETS K2-21B AND K2-21C FROM TRANSIT TIMING VARIATIONS
No full textThe Kepler Space Telescope uncovered thousands of exoplanet candidates before the failure of its second reaction wheel. The redesigned Kepler mission (K2) went on to discover thousands more candidates along the ecliptic. We investigate the K2-21 system, which consists of two close-in exoplanets with orbital periods of ~9.32 and 15.5 days. The ratio of the orbital period is near 5:3, but the resonant angle is not librating over the timescale of observation indicating that the planets are not in a mean motion resonance. The proximity between these exoplanets can force strong transit timing variations (TTVs) with an amplitude of ~30 minutes (early or late) through their gravitational interactions. From the measured TTVs, we estimate the mass of each planet as 1.58 and 3.88 times larger than Earth’s mass and both planets exist on low-eccentricity orbits (e \u3c 0.1). As a result, K2-21b and K2-21c are similar to Neptune with respect to their bulk composition and likely have atmospheres dominated by hydrogen and/or helium. These planets add to the large population of sub-Neptunian worlds discovered using the method of TTVs
TROJAN PLANET PACKING WITHIN THE HABITABLE ZONE OF ALPHA CENTAURI
No full textThe Kepler Mission uncovered a multitude of exoplanet candidates, where astronomers identified two new classes of planet not found in our Solar System (e.g., Super-Earths and Mini-Neptunes). Some researchers proposed that Kepler could also discover planetary systems with Trojan planets, where two planets orbit the star at the same semimajor axis but separated by 60 degrees in orbital phase. The method of transit timing variations was responsible for two new classes, but the detection of a pair of Trojan planets remained elusive. We are motivated to investigate the possibility of Trojan planets in Alpha Centauri AB, given the tentative detection of a Trojan planet in PDS 70 using observations from ALMA (Balsalobre-Ruza et al. 2023). We simulate Trojan planets orbiting Alpha Cen A using the n-body simulation code rebound, which allows us to evaluate the stability of Trojan systems under the strong perturbation of a stellar companion (Alpha Cen B). We find that a pair of Trojan planets can orbit Alpha Cen A for ~50 kyr without significant changes in the planetary semimajor axes, which indicates that long-term stability is possible despite perturbations from the stellar companion. Our preliminary result suggests that Trojan planets in binaries are possible, which may double the prospects for habitable planets if such worlds are Earth-like
DAISYWORLD REVISITED: APPLICATIONS TO KEPLER-62F
No full textPlanetary habitability is typically defined by whether an Earth-sized planet resides within the habitable zone (i.e., region where liquid surface water is possible). However, the ubiquity of lifeforms on Earth’s surface additionally depends on the distribution of light reaching the surface. We explore this dependence on Kepler-62f using a classic toy model called DaisyWorld, which couples the physical properties of two theoretical species of daisy with the surface temperature. Our modeled surface temperatures vary with latitude and are derived from a 1D energy balance climate model assuming an Earth-like obliquity. We find that our more realistic model introduces a seasonal dependence on the daisy population with the dark colored daisies dominating higher latitudes. Temperature-dependent extremophiles are a prime suspect for the last common universal ancestor of life on Earth, which makes our results using a temperature dependent daisy an important stepping-stone to broader investigations for life beyond our Solar System
Preliminary checklist of amphipod crustaceans from Sapelo Island, GA
Get PDFAmphipods belonging to the subphylum Crustacea inhabit many aquatic habitats, and they can often inform scientists and researchers about various environmental conditions, acting as biological indicators, yet documentation of amphipod species is lacking in the state of Georgia. During this study amphipods were collected from around Sapelo Island, GA, imaged, and identified. A preliminary checklist and identification key to Sapelo Island amphipods is provided. This checklist and key will be useful for researchers and citizen scientists alike, for monitoring the health of the environment, surveying biodiversity, and for use in other applied studies
BROAD SCALE PHYLOGEOGRAPHY OF THE BANDED WATER SNAKE, NERODIA FASCIATA**
No full textGeographic barriers to dispersal are a major cause of reproductive isolation, which can lead to divergence and speciation. However, the interaction of different taxa with these barriers varies across taxonomic and geographic scales. In the southeastern coastal plain, several phylogeographic patterns have emerged in response to shared landscapes. For instance, during the last glacial maximum, many species were restricted to “refugia” in the southern U.S. Isolation is thought to have persisted during interglacial periods by major rivers made wider by melting glacier water allowing for expansion north and south but restricting gene flow east and west. There is also evidence that during interglacial periods some species were isolated to peninsular Florida which had been rendered an island by high sea levels, causing deep divergences between these populations and the rest of their species. Herein, we test these hypotheses in the banded water snake (Nerodia fasciata), whose range spans several such potential biogeographic barriers. We will use both nuclear and mtDNA to test for phylogeographic structure and evaluate the impact of geographic barriers (i.e., major drainage systems and glacial refugia) on diversification of this group. This study will test the validity of three named subspecies of N. fasciata and determine if peninsular Florida and the Mississippi and Apalachicola Rivers have acted as biogeographic barriers for this species and how glacial refugia played a role in their evolution. Quantifying diversification across landscapes will promote the understanding of broad scale evolutionary processes
SPECIES DISCRIMINATION OF VIBRIO HARVEY CLADE PRIMERS, AND THE FIRST REPORT ON V. HARVEYI AND V. CAMPBELLII IN SOUTHEASTERN U.S.A. WATERS**
No full textIn our recent study, a wide array of virulence genes carried by Vibrio Harveyi clade pathogens has been detected in Georgia aquaculture waters and sediments. Identification of their carriers was attempted with qPCR and a set of previously published species-specific primers. Based on their described selectivity, the following primers were selected and used. Vibrio alginolyticus was targeted with gyrB gene set of primers, and V. parahaemolyticus was targeted with toxR gene set of primers. Due to a lack of primers distinguishing between Vibrio harveyi and Vibrio campbellii, both species were targeted simultaneously with rpoA gene set of primers. Related to the clade Vibrio splendidus was targeted with 16S rRNA gene set of primers. The set of primers for V. splendidus strongly cross-reacted with all species. The set of primers for V. parahaemolyticus cross-reacted with V. alginolyticus and V. campbellii. Previously, these primers have been reported as discriminating between species of Harveyi clade. Our results call for more careful testing of published species-specific primers and qPCR parameters; and possibly for re-evaluation of published data obtained with the above primers by purchasing new primers. The set of primers for gyrB in V. alginolyticus, and for rpoA gene in V. harveyi and V. campbellii exhibited clear discrimination between Vibrio Harvey clade species. No cross-reactions with any other Harveyi clade species or negative control were observed. With the rpoA set of primers, V. harveyi and V.campbelli were detected in water and sediments collected from clams (Mercenaria mercenaria) aquaculture and reefs of wild eastern oysters (Crassostrea virginica). Either one or both of these Vibrio species were detected from June through October with much higher concentrations in sediments. This is the first report on V. harveyi and V. campbellii pathogens in Southeastern USA waters which indicates that Vibrio species are expanding to new territories
ANALYSIS OF ANTIBACTERIAL PROPERTIES IN ESSENTIAL OILS
No full textAntibiotic resistance is an increasing crisis within the healthcare industry. Antibiotics used to eliminate bacterial infections in humans are often in the form of synthetic chemicals. When a new antibiotic is introduced to humans, it takes an average of three years for bacteria to become resistant to the antibiotic, due to improper use of antibiotics. Essential oils are naturally occurring organic compounds that are extracted from plants and have been recognized by the homeopathic community as potential alternatives for pharmaceutical treatment. Several essential oils exhibit similar properties to antibiotics in that they are able to prevent the further growth of bacteria. Using the Kirby-Bauer Disk Diffusion Susceptibility Test Protocol, three essential oils were tested for their ability to prevent bacterial growth. Essential oils tested included lavender (Lavandula angustifolia), oregano (Origanum vulgare) and lemongrass (Cymbopogon citratus). Each essential oil was tested with a Gram-negative bacterium (Escherichia coli) and a Gram-positive bacteria (Staphylococcus epidermidis). The antibiotic amoxicillin was used as a positive control to compare the effectiveness of essential oils. Each experiment was completed with five replicates per treatment group. The results for the ANOVA (SPSS version 27) showed a significant difference in the average zone of inhibitions for each essential oil (F=66.844, sig.=0.000). Lemongrass essential oil was excluded from the ANOVA as it promoted growth. A Tukey post-hoc test was completed and revealed that lavender and amoxicillin performed similarly, while oregano performed more effectively than both lavender and amoxicillin. This experiment demonstrates that essential oils can just as effective or more effective than antibiotics for both Gram-positive and Gram-negative bacteria. Further research is needed to determine which organic compound is responsible for the antibiotic properties of essential oils as there are multiple compounds in essential oils. Once these compounds have been identified and isolated, their use in pharmaceutical applications can further researched