Auburn University
  • Auburn, United States
Recent publications
Thirteen elements were measured in 76 surface grab sediment samples and 90 segments of four cores from Lakes Erie and Ontario. By combining the data obtained previously from Lakes Superior, Michigan, and Huron, the spatial distribution, temporal trends, major influencing factors, anthropogenic enrichments, categorization, and ecological risks of target metals in sediment were evaluated for the Great Lakes region. Regionwide, Lake Ontario had the highest median concentrations for Ag, As, Cd, Zn, and Pb, while the highest Cr concentrations were found in the Western Basin of Lake Erie. Within Lake Ontario, Ag concentration tended to be higher towards the east. Temporal trends of the net fluxes were described by pseudo first order kinetics for selected metals in Lake Ontario. It may take more than a hundred years for the surface fluxes to decrease to the background level. The highest enrichment factor was found in Lake Ontario for Ag; while for Pb, Lake Michigan was more enriched than the other lakes. Pearson correlation, principal component, and hierarchical clustering analyses were applied to the concentration data, and, for the first time, to the estimated enrichment factor to gain insight to the human impact. Results of risk quotient analysis showed high environmental risks in most cases. Overall, the highest risk was found for Lake Ontario, followed by Lakes Erie, Superior, Huron, and Michigan. The risk quotient was strongly correlated with the enrichment factor, implying that human activities could have unfavorably affected benthic biota in the sediment of the Great Lakes.
This study evaluated the effects of calcium butyrate (CB) and bacitracin methylene disalicylate 50 (BMD) combined with different phytase concentrations on broiler intestinal health and physiology. Day-old YPM x Ross 708 male broilers (2,880) were distributed in 72 floor pens and assigned to 1 of 9 treatments (8 replicates/treatment). This experiment was a factorial arrangement including 2 phytase concentrations (500 or 1,500 FTU/kg) and 4 microbiota modulating feed additive levels (MMFA; (1) none, (2) only CB (0.5 g/kg of diet), (3) only BMD (55 mg/kg of diet), or (4) both CB and BMD). Additionally, a negative control without phytase and MMFA was included. Intestinal permeability was assessed on d 27. Jejunum wall and cecal content samples were collected on d 28 and 42 to assess jejunum villus height (VH), crypt depth, tight-junction and mucin gene expression, cecal microbiome diversity, and predicted bacterial metabolic pathways. Phytase and MMFA did not influence intestinal permeability (P > 0.05). Combining both CB and BMD with 1,500 FTU/kg of phytase compared to 500 FTU/kg lowered d 28 VH (P ≤ 0.05). Jejunal expression of CL-1, CL-4, CL-5, and ZO-2 on d 28 as well as CL-2 on d 42 changed between MMFA when combined with 1,500 FTU/kg of phytase but not 500 FTU/kg (P ≤ 0.05). Day 42 Pielou's evenness increased when 1,500 FTU/kg of phytase was combined with both CB and BMD compared to no MMFA (P ≤ 0.05). The cecal microbial beta diversity was not influenced by phytase, MMFA, or their interaction (P > 0.05). Overall, broiler intestinal health and physiology were influenced by CB and BMD depending on phytase concentration, demonstrating the complex interactions between these feed additives.
Select electron-propagator (EP) methods agree as closely with experimental standards for molecular vertical ionization energies as they do with computational data of nearly full-configuration-interaction quality. Several EP methods consistently attain higher accuracy than alternatives with equal arithmetic bottlenecks expressed in terms of occupied (O) and virtual (V) orbital dimensions. The cubically scaling methods realize a mean absolute error (MAE) below 0.2 eV and are feasible whenever conventional self-consistent-field calculations are performed. O²V³-scaling EP self-energies achieve an MAE slightly above 0.1 eV and are as feasible as conventional second-order perturbative calculations of total energies. OV⁴ methods are more accurate (MAEs ∼0.075 eV) than ΔCCSD(T) and are more efficient than third-order total-energy calculations. An equally accurate generalization with full self-energy matrices and non-iterative O²V⁴ contractions produces Dyson orbitals in their most general form. Composite EP models that accurately estimate the effects of basis-set saturation drastically improve efficiency without sacrificing accuracy. No adjustable parameters are employed in the self-energy formulas or in the generation of reference-state orbitals. When Dyson-orbital probability factors indicate that Koopmans’s theorem is qualitatively valid, simple perturbative corrections suffice to approach chemical accuracy.
Effective disease and pest management in peanut (Arachis hypogea L.) requires adequate spray penetration within the canopy during pesticide applications. Field studies were conducted to assess spray deposition within the peanut canopy at three carrier volumes of 10, 15 and 20 gallons per acre (GPA), with each volume applied using three different nozzle types (extended range [XRC], air induction extended range [AIXR], and Turbo TeeJet Induction [TTI]). Spray deposition was assessed using water at various application timings (45, 60, 90, and 120 DAP) by placing water‐sensitive paper at upper, middle, and lower positions within the peanut canopy. Fungicide applications using different carrier volume and nozzle treatments were made at regular intervals throughout the season, and disease ratings along with peanut yield were recorded at harvest. The carrier volume of 20 GPA consistently provided the greatest deposition in the upper and middle canopy, followed by 15 and 10 GPA. The XRC nozzle exhibited the greatest deposition in the upper canopy, followed by the AIXR and TTI nozzles. Within the lower canopy, the effect of carrier volume and nozzle type on spray deposition varied among the application timings. For disease control, the lower carrier volume of 10 GPA and XRC nozzle showed an increased incidence of late leaf spot (Nothopassalora personata) and southern stem rot (Sclerotium rolfsii Sacc.) in one of the study years. Carrier volume and nozzle type did not affect peanut yield during both years. Overall, the findings suggest that spray deposition within the peanut canopy is influenced by carrier volume and nozzle type; however, it does not necessarily lead to reduced peanut yield, especially in most fields with low to moderate disease pressure.
Ecotourism promises to reconcile wildlife conservation and human development if negative impacts of human visitation and associated infrastructure can be minimized. Animal behavior studies can be used to identify individual and population responses to anthropogenic impacts before other fitness consequences are documented. With input from professionals in animal behavior and ecotourism, we identified key questions needed to better understand the impact of ecotourism on wildlife. Activity budgets, foraging, movement, stress, habituation, and reproduction were themes that emerged from our survey. We highlight promising research on these themes and identify remaining behavioral research questions about conserving wildlife in the context of ecotourism. Although ecotourism activities often have detrimental effects on animal behavior, we highlight research needs that can inform management and ecotourist education to improve human behavior to be more compatible with sustainable use of nature.
Plain Language Summary Precipitation loss plays a major role in removing ions from the ring current and is a key reason why the ring current decays quickly during geomagnetic storms. Understanding the evolution of proton precipitation loss is critical to better understanding the ring current dynamics. Recent observations show the development of a notable reduction in phase space density (PSD) radial profiles, called deepening PSD minima, indicating fast local precipitation loss potentially caused by wave‐induced scattering. In this study, we present a comprehensive analysis of the evolution of ring current protons in Earth's inner magnetosphere, specifically focusing on these deepening PSD minima. Using >6 years of observations from the Van Allen Probes, we show that the overall occurrence rates of proton deepening PSD minimum peaks at ∼3%, mainly located at ∼4.5–5.0 Earth radii. The occurrence rate increases with increasing levels of geomagnetic/solar wind conditions. Theoretical calculations indicate that these protons with deepening PSD minima can resonate with electromagnetic ion cyclotron (EMIC) waves, a major type of plasma waves in Earth's magnetosphere. As a result, our study suggests that EMIC waves are the likely cause of the deepening PSD minima and contribute to the fast local loss of ring current protons.
Tectonic structures such as wrinkle ridges, lobate scarps, small‐scale graben, and tectonic pits reveal the recent lunar activity and complex deformational processes. Despite numerous studies, the northeastern region of the Mare Serenitatis basin, including the Posidonius crater, has yet to be studied in detail. This research presents a comprehensive analysis of tectonic structures in this region, revealing ∼808 km of wrinkle ridges, ∼286 km of lobate scarps, ∼346 km of small‐scale graben, and ∼269 tectonic pits. We identified 412 craters deformed by wrinkle ridges, 55 craters by lobate scarps, and 108 craters by small‐scale graben, suggesting extensive recent deformation. Chronological analysis of wrinkle ridges and lobate scarps revealed young ages ranging from ∼29−9+10 299+10{\sim 29}_{-9}^{+10} Ma to ∼120 ± 30 Ma close to the crater, whereas Posidonius crater resurfaced floor age tend to ∼2.8−0.5+0.4 2.80.5+0.4{\sim} {2.8}_{-0.5}^{+0.4} Ga. Our study suggests that the blind thrust fault deformed the western floor of the Posidonius crater, with small‐scale graben with pits plausibly developed during the reactivation. Orthogonal transitions that occur between adjacent wrinkle ridges and lobate scarps in the study area could be a splay fault of the blind thrust fault and likely formed during the reactivation. This reactivation plausibly resulted from a combination of recession stresses, diurnal tidal stresses, and global contraction. Additionally, a combination of complex processes─intrusion, subsidence, and tectonics associated with the blind thrust fault plausibly influenced Rima Posidonius. Overall, this study suggests that the northeastern region of the Mare Serenitatis basin witnessed recent tectonic activity and could be a potential site for future exploration missions.
Oceanic plate seamounts are believed to play an important role in megathrust rupture at subduction zones, although consistent relationships between subducting seamounts and plate interface seismicity patterns are not found. While most studies focus on impacts linked to their topography, seamounts are also sites of heterogeneity in incoming plate sediments that may contribute to megathrust properties. Here, we characterize incoming plate sediments along the Cascadia subduction zone using new high‐resolution seismic images and compressional wave (Vp) models from the CASIE21 multi‐channel‐seismic experiment. Nine fully‐to‐partially buried seamounts are identified seaward of the deformation front within a region of thick Plio‐Pleistocene sediment where the Juan de Fuca plate is bending into the subduction zone. Anomalously high Vp sediment blankets two seamounts offshore Washington‐Central Oregon, with wavespeeds reaching 36% and 20% higher than adjacent sediment. Fluid seepage and temperatures warm enough for smectite diagenesis extending to shallow depths are inferred from heat flow studies and we attribute Vp anomalies to sediment cementation linked primarily to smectite dehydration. Signatures of fluid seepage above seamounts are also identified offshore Vancouver Island, but anomalously low Vp sediment below distinct reverse polarity reflections are found, indicating trapped fluids, and cooler basement temperatures are inferred. Landward of one seamount, a zone of enhanced sediment compaction is found, consistent with the predicted stress modulating effects of seamount subduction. These new findings of variations in sediment diagenesis and strength around seamounts prior to subduction may contribute to the diverse megathrust frictional properties and seismicity patterns evident at subducting seamounts.
The range and density of one of North America's most destructive and invasive mammalian species, wild pigs (Sus scrofa), has expanded rapidly over the past several decades. Alongside this growth, their fecal contamination of surface waters has impaired water quality through significantly increased levels of pathogenic bacteria, raising concerns over the potential for zoonotic disease transmission. Significant remediation of these water quality impacts has been shown as a result of reductions in wild pig populations due to control efforts; however, the duration of these remediation effects as populations rebound remains unclear. Our study sought to determine the longevity of water quality remediation resulting from wild pig population control efforts. We found that median concentrations of Escherichia coli and fecal coliform (CFU/100 mL) increased by 746% and 159% in the year following the conclusion of removal efforts, resulting in median concentrations of 79% and 159% greater than those observed prior. We also found increased public health risk, with samples exceeding E. coli and fecal coliform guidelines 10% and 12% more often than pre‐removal, respectively. While further research into wild pig population dynamics and fecal contamination is necessary, we conclude that ongoing population control efforts may be necessary to remediate water quality impacts and public health risks associated with invasive wild pigs.
It is widely accepted that repetitive chorus waves are responsible for the internal modulation of pulsating auroras. Recent studies have indicated that the repetitive nature of chorus waves stems from continuous electron injection. By employing a one-dimensional general curvilinear plasma simulation code, we introduce periodic electron injection into the simulation system. This generates repetitive rising-tone chorus waves, subsequently resulting in periodic electron precipitation, which potentially contributes to the formation of pulsating auroras. There is a distinct one-to-one correlation between each chorus element and the prompt electron precipitation. Moreover, we find that such electron precipitations are primarily driven by nonlinear interactions with chorus elements via nonlinear interactions, specifically phase bunching. Our work suggests that electron injection can modulate the electron precipitation by controlling the repetition period of chorus waves, thereby potentially influencing the period of internal modulation of pulsating auroras.
A new approach that allows for the calculation of interaction-induced properties exclusively from the properties of monomers is presented. The method is derived in the spirit of the symmetry-adapted perturbation theory (SAPT). The interaction-induced property is presented in the first order of the molecular interaction operator, including the exchange effects. Test calculations of the interaction induced dipole moment were carried out for a number of small nonpolar and polar atomic and molecular dimers. The numerical results show that the analytical first-order corrections proposed in this paper reproduce the finite-field treatment of the first-order corrections of SAPT. Compared to supermolecular approaches, the performance of the finite-field SAPT (up to the second order) constitutes an insightful alternative for calculations of interaction-induced properties.
MagNetUS is a network of scientists and research groups that coordinates and advocates for fundamental magnetized plasma research in the USA. Its primary goal is to bring together a broad community of researchers and the experimental and numerical tools they use in order to facilitate the sharing of ideas, resources and common tasks. Discussed here are the motivation and goals for this network and details of its formation, history and structure. An overview of associated experimental facilities and numerical projects is provided, along with examples of scientific topics investigated therein. Finally, a vision for the future of the organization is given.
The synonymies of the echinochasmid genera Mesorchis Dietz, 1909 and Monilifer Dietz, 1909 with Stephanoprora Odhner, 1902 remain contentious and unresolved with morphology. To explore the matter, we herein provide a supplemental description of the type species of Stephanoprora, Stephanoprora ornata Odhner, 1902, based on specimens we collected from the intestine of a Nile crocodile Crocodylus niloticus Laurenti, 1768 (Crocodylia: Crocodylidae) captured in the Kavango River, Namibia. No nucleotide information was available previously for S. ornata. Morphology plus 28S and ITS2 phylogenetic analyses suggested Stephanoprora is a monotypic genus that can be differentiated from other genera by having 26 collar spines. Stephanoprora differs from Mesorchis by the number and distribution of collar spines (26 [2 dorsal spines, 12 lateral spines, 12 corner spines] vs. 22 [2 dorsal spines, 12 lateral spines, 8 corner spines] in Mesorchis), length of the pre-pharyngeal oesophagus, pharynx position posterior to collar (vs. pre-pharyngeal oesophagus short, pharynx anterior to or at level of corner spines), and testes shape (elongate-ovoid, irregular in outline vs. ovoid, atypically elongated). Our 28S and ITS2 phylogenies recovered the new sequence of S. ornata (having 26 collar spines) sister to all remaining echinochasmid sequences, representing species that have 20–24 collar spines. Echinochasmus Dietz, 1909 and Mesorchis were recovered as paraphyletic. We retain Monilifer as a junior subjective synonym of Echinochasmus based a suite of morphological features related to body shape and genitalia and because the designated type for Monilifer was reassigned to Echinochasmus. We accept 25 species of Mesorchis.
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9,237 members
Anh Nguyen
  • Department of Computer Science & Software Engineering
Vitaly Vodyanoy
  • Department of Anatomy, Physiology and Pharmacology
Hulya Kirkici
  • Department of Electrical & Computer Engineering
V. Mulabagal
  • Samuel Ginn College of EngineeringDepartment of Civil Engineering
Wendy Hood
  • Department of Biological Sciences
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Auburn, United States
Head of institution
Dr. Mario Eden