School of Plant and Environmental Sciences
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SPES was formed in 2017 from three departments: Crop and Soil Environmental Sciences; Horticulture; and Plant Pathology, Physiology, and Weed Science.
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Browsing School of Plant and Environmental Sciences by Department "Biomedical Engineering and Mechanics"
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- Caging the blob: using a slime mold to teach concepts about barriers that constrain the movement of organismsBohland, Cynthia E.; Schmale, David G. III; Ross, Shane D. (University of California Press, 2011-11-01)Few laboratory exercises are designed to teach biology students about barriers that may constrain the movement of organisms. We describe a unique inquiry-based exercise involving Lego mazes (the barrier) and the plasmodial slime mold, Physarum polycephalum (the organism). During guided inquiry, students construct mazes using Lego brand building blocks and the slime mold is allowed to "navigate" through the maze and "respond" to the barrier. Students then generate and test hypotheses about the movement of the slime mold in response to different barriers in the open-inquiry phase of the investigation.
- Intercomparison of Small Unmanned Aircraft System (sUAS) Measurements for Atmospheric Science during the LAPSE-RATE CampaignBarbieri, Lindsay; Kral, Stephan T.; Bailey, Sean C. C.; Frazier, Amy E.; Jacob, Jamey D.; Reuder, Joachim; Brus, David; Chilson, Phillip B.; Crick, Christopher; Detweiler, Carrick; Doddi, Abhiram; Elston, Jack; Foroutan, Hosein; González-Rocha, Javier; Greene, Brian R.; Guzman, Marcelo I.; Houston, Adam L.; Islam, Ashraful; Kemppinen, Osku; Lawrence, Dale; Pillar-Little, Elizabeth A.; Ross, Shane D.; Sama, Michael P.; Schmale, David G. III; Schuyler, Travis J.; Shankar, Ajay; Smith, Suzanne W.; Waugh, Sean; Dixon, Cory; Borenstein, Steve; de Boer, Gijs (MDPI, 2019-05-10)Small unmanned aircraft systems (sUAS) are rapidly transforming atmospheric research. With the advancement of the development and application of these systems, improving knowledge of best practices for accurate measurement is critical for achieving scientific goals. We present results from an intercomparison of atmospheric measurement data from the Lower Atmospheric Process Studies at Elevation—a Remotely piloted Aircraft Team Experiment (LAPSE-RATE) field campaign. We evaluate a total of 38 individual sUAS with 23 unique sensor and platform configurations using a meteorological tower for reference measurements. We assess precision, bias, and time response of sUAS measurements of temperature, humidity, pressure, wind speed, and wind direction. Most sUAS measurements show broad agreement with the reference, particularly temperature and wind speed, with mean value differences of 1.6 ± 2.6 ∘ C and 0.22 ± 0.59 m/s for all sUAS, respectively. sUAS platform and sensor configurations were found to contribute significantly to measurement accuracy. Sensor configurations, which included proper aspiration and radiation shielding of sensors, were found to provide the most accurate thermodynamic measurements (temperature and relative humidity), whereas sonic anemometers on multirotor platforms provided the most accurate wind measurements (horizontal speed and direction). We contribute both a characterization and assessment of sUAS for measuring atmospheric parameters, and identify important challenges and opportunities for improving scientific measurements with sUAS.
- Lagrangian coherent structures are associated with fluctuations in airborne microbial populationsTallapragada, Phanindra; Ross, Shane D.; Schmale, David G. III (American Institute of Physics, 2011-09-01)Many microorganisms are advected in the lower atmosphere from one habitat to another with scales of motion being hundreds to thousands of kilometers. The concentration of these microbes in the lower atmosphere at a single geographic location can show rapid temporal changes. We used autonomous unmanned aerial vehicles equipped with microbe-sampling devices to collect fungi in the genus Fusarium 100 m above ground level at a single sampling location in Blacksburg, Virginia, USA. Some Fusarium species are important plant and animal pathogens, others saprophytes, and still others are producers of dangerous toxins. We correlated punctuated changes in the concentration of Fusarium to the movement of atmospheric transport barriers identified as finite-time Lyapunov exponent-based Lagrangian coherent structures (LCSs). An analysis of the finite-time Lyapunov exponent field for periods surrounding 73 individual flight collections of Fusarium showed a relationship between punctuated changes in concentrations of Fusarium and the passage times of LCSs, particularly repelling LCSs. This work has implications for understanding the atmospheric transport of invasive microbial species into previously unexposed regions and may contribute to information systems for pest management and disease control in the future.
- Quantification of zearalenone and α-zearalenol in swine liver and reproductive tissues using GC-MSPack, Erica; Stewart, Jacob; Rhoads, Michelle; Knight, James W.; De Vita, Raffaella; Clark-Deener, Sherrie; Schmale, David G. III (Elsevier, 2020-12-01)The mycotoxin zearalenone (ZEN) is a common contaminant of swine feed which has been related to a wide range of reproductive anomalies in swine, such as pelvic organ prolapse, anestrous, and pseudopregnancy. New information is needed to understand how ZEN and related metabolites accumulate in swine reproductive tissues. We conducted a feeding study to track ZEN and the metabolite α-zearalenol (α-ZEL) in swine liver and reproductive tissues. Thirty pubertal gilts were randomly assigned one of three treatments, with ten pigs in each treatment group: (1) base feed with solvent for 21 days, (2) ZEN-spiked feed for seven days followed by base feed with solvent for 14 days, and (3) ZEN-spiked feed for 21 days. At the end of the trial, liver, anterior vagina, posterior vagina, cervix, uterus, ovaries, and broad ligament were collected from pigs. ZEN was found in the anterior vagina, posterior vagina, cervix, and ovaries, with significantly higher concentrations in the cervix relative to other reproductive tissues. ZEN and α-ZEL were found in liver tissue from pigs in each treatment group. Our results show that ZEN accumulates more in the cervix than other reproductive tissues. The presence of ZEN in reproductive tissues may be indicative of ZEN-related reproductive symptoms. Future work could examine how ZEN concentrations vary in reproductive tissues as a factor of the pigs age, weight, sex, or parity, to establish parameters that make pig more sensitive to ZEN.
- Vortex-induced dispersal of a plant pathogen by raindrop impactKim, Seungho; Park, Hyunggon; Gruszewski, Hope A.; Schmale, David G. III; Jung, Sunghwan (NAS, 2019)Raindrop impact on infected plants can disperse micron-sized propagules of plant pathogens (e.g., spores of fungi). Little is known about the mechanism of how plant pathogens are liberated and transported due to raindrop impact.We used high-speed photography to observe thousands of dry-dispersed spores of the rust fungus Puccinia triticina being liberated from infected wheat plants following the impact of a single raindrop.We revealed that an air vortex ring was formed during the raindrop impact and carried the dry-dispersed spores away from the surface of the host plant. The maximum height and travel distance of the airborne spores increased with the aid of the air vortex. This unique mechanism of vortex-induced dispersal dynamics was characterized to predict trajectories of spores. Finally, we found that the spores transported by the air vortex can reach beyond the laminar boundary layer of leaves, which would enable the long-distance transport of plant pathogens through the atmosphere.
- Wind-driven spume droplet production and the transport of Pseudomonas syringae from aquatic environmentsPietsch, Renee B.; Grothe, Hinrich; Hanlon, Regina; Powers, Craig W.; Jung, Sunghwan; Ross, Shane D.; Schmale, David G. III (PeerJ, 2018-09-26)Natural aquatic environments such as oceans, lakes, and rivers are home to a tremendous diversity of microorganisms. Some may cross the air-water interface within droplets and become airborne, with the potential to impact the Earth’s radiation budget, precipitation processes, and spread of disease. Larger droplets are likely to return to the water or adjacent land, but smaller droplets may be suspended in the atmosphere for transport over long distances. Here, we report on a series of controlled laboratory experiments to quantify wind-driven droplet production from a freshwater source for low wind speeds. The rate of droplet production increased quadratically with wind speed above a critical value (10-m equivalent 5.7 m/s) where droplet production initiated. Droplet diameter and ejection speeds were fit by a gamma distribution. The droplet mass flux and momentum flux increased with wind speed. Two mechanisms of droplet production, bubble bursting and fragmentation, yielded different distributions for diameter, speed, and angle. At a wind speed of about 3.5 m/s, aqueous suspensions of the ice-nucleating bacterium Pseudomonas syringae were collected at rates of 283 cells m−2 s−1 at 5 cm above the water surface, and at 14 cells m−2 s−1 at 10 cm above the water surface. At a wind speed of about 4.0 m/s, aqueous suspensions of P. syringae were collected at rates of 509 cells m−2 s−1 at 5 cm above the water surface, and at 81 cells m−2 s−1 at 10 cm above the water surface. The potential for microbial flux into the atmosphere from aquatic environments was calculated using known concentrations of bacteria in natural freshwater systems. Up to 3.1 × 104 cells m−2 s−1 of water surface were estimated to leave the water in potentially suspended droplets (diameters <100 µm). Understanding the sources and mechanisms for bacteria to aerosolize from freshwater aquatic sources may aid in designing management strategies for pathogenic bacteria, and could shed light on how bacteria are involved in mesoscale atmospheric processes.