Deep-Water Near-Bottom Turbulence in Lake Michigan: An Underwater Investigation

Motivated by a need to characterize near-bottom deep-water turbulence for an understanding of the filtration capabilities of invasive quagga mussels, an instrument tripod was deployed in Lake Michigan for six months in 60m of water to measure current velocities, with specific interest being paid to near-bottom (0.10 to 0.95 meters above bottom) velocities during the deployment. The deployment period (September 2012-April 2013) was characterized by very little stratification and a median temperature of about throughout the water column. A mean horizontal velocity of 3.6 cm/s with a standard deviation of 2 cm/s was also measured at 1 meter above the lake bed. In spite of the 60m depth of the measurement site, surface waves were found to influence near-bottom velocities for a significant fraction of the time, with periods between 6.5 and 12.5 seconds. Fluctuations in velocity were used to quantify turbulence through the use of turbulent kinetic energy (tke) calculations, while simple spectral analysis was used to verify tke levels and identify possible wave contamination. At distances greater than 500 z+ from the bed, turbulent kinetic energy levels follow canonical scaling with values of approximately 5. However, very near-bottom tke levels are greatly elevated relative to the expected values, which we speculate may be due to mussel-induced currents. These conclusions coupled with further modeling will allow for the development of mussel-influence models that will prove important to understanding the impact of these invasive species

Full-Water Column Turbulence Parameterization of Stratified Waters in Southern Lake Michigan

Full water column mean flow and turbulence structure was characterized at two stratified locations in Lake Michigan (a. Muskegon, MI; b. Michigan City, IN) in order to better understand the filtration potential of invasive quagga mussels. Invasive quagga mussels in Lake Michigan are filter feeders and can dramatically alter clarity as well as the biological/chemical characteristics of the water column. This filtering capacity is highly contingent on turbulence characteristics throughout the water column, which is poorly understood in the Great Lakes. Using velocity, temperature, and turbulence data collected from these locations, the structure of the water column turbulence was modeled for site (a) using data from 2011 and measured for site (b) in 2017. The data from 2017 was collected as a test run of a new acoustic Doppler current profiler, the Nortek Signature500, that will be utilized in future experiments on Lake Michigan. This data was analyzed to better characterize the turbulence structure of Lake Michigan and how it is affected by wind events and wave trends. Using power spectra and turbulence structure function, the turbulent kinetic energy dissipation of the full water column was analyzed from these two locations. This analysis provides insight into the turbulence structure of the full-water column in a stratified lake and will be utilized to prepare for the execution of future sampling events in Lake Michigan

Velocity Profiling, Turbulence, and Chlorophyll Concentrations in the Bottom Boundary Layer of Lake Michigan near Muskegon, Michigan

The characterization of water flow and turbulence near lake beds is important for modelling environmental and ecological effects throughout a lake. In Lake Michigan, where invasive filter-feeding Quagga mussels dominate the lake bed, turbulence plays an important role in determining how much of chlorophyll is mixed down to the Quagga Mussels. Deep in Lake Michigan (44m) near Muskegon, MI, a large tripod was deployed, attached with an Acoustic Doppler Velocimeter, a fluorometer to measure chlorophyll concentrations, and a temperature sensor. Measurements were recorded from late May until early August by sampling velocities every hour in ten-minute bursts at 4 Hz, and sampling temperature and concentration approximately every minute, continuously. Several important turbulent parameters were calculated using the data collected. Chlorophyll data from the site showed that the water column here displayed a Concentration Boundary Layer (CBL), in which the chlorophyll concentration increases as distance from the lake floor increases. The median speed (U = 2.85cm/s) and Turbulent Kinetic Energy (TKE = 2.1 x 10-5 m2/s2) were also calculated. All of these results have previously had very little documentation in such deep waters. The observation of a CBL shows that the invasive Quagga Mussels are able to drastically alter chlorophyll concentrations near the lake floor, an important result for future modeling efforts. The quantification of turbulence parameters will be useful in further studies to find causation between various turbulence levels and concentrations

Adventures in Paragraph Writing: The Development and Refinement of Scalable and Effective Writing Exercises for Large-enrollment Engineering Courses

Adventures in paragraph writing: the development and refinement of scalable and effective writing exercises for large enrollment engineering courses. The ability to communicate effectively is a highly desirable attribute for today’s graduating engineers. Additionally, the inclusion of communication components in technical courses has been shown to enhance learning of technical content and can be leveraged to satisfy non-technical learning outcomes. However, the incorporation of such components in undergraduate engineering curricula remains challenging due to resource limitations, credit hour crunches, and other issues. This paper presents the design considerations and preliminary results from our ongoing work to create an effective, transferrable, low-overhead approach to paragraph writing exercises suitable for inclusion in any large engineering course. Key considerations in the development of these exercises include: identification of the motivations and learning outcomes for each exercise; development and tailoring of writing prompts (questions) appropriate for these outcomes; and the development and implementation of an assessment and feedback strategy,including resource-efficient grading rubrics and techniques.Results are reported from the application of the paragraph writing exercise in a large civil engineering undergraduate fluid mechanics course (120 students; approximately 15 assignments). A primary focus of this first application centered on two key components that must be refined in order for the exercise to be effective and transferrable: (1) the selection of writing prompts, and (2) assessment and feedback. Analysis of student paragraphs highlights the importance of the writing prompts in the success of the exercise, indicating that specific word choice, question focus, and supplemental instruction greatly affected the level of writing students submitted. Some writing prompts were selected to address and enhance technical content in the course, while other writing prompts were developed to broaden student awareness of engineering in societal, environmental, and global contexts. In addition to developing productive writing prompts, the assessment and feedback strategies were evaluated using student surveys and feedback. While minimal marking and holistic rubric assessment methods proved effective from a grading resource standpoint, students were frustrated by the lack of feedback associated with these techniques and uncomfortable with the holistic grading rubric. Data from student surveys point to the importance of giving meaningful feedback to students, and providing them with opportunities to revise their written submissions. Student surveys also highlighted an unforeseen obstacle to the exercise: student resistance to writing in technical courses. We provide several suggestions for overcoming student resistance, as well as improved assessment and feedback strategies that better meet student needs while still not over-burdening instructors and teaching assistants

Genetic Architecture of Soybean Yield and Agronomic Traits

Soybean is the world’s leading source of vegetable protein and demand for its seed continues to grow. Breeders have successfully increased soybean yield, but the genetic architecture of yield and key agronomic traits is poorly understood. We developed a 40-mating soybean nested association mapping (NAM) population of 5,600 inbred lines that were characterized by single nucleotide polymorphism (SNP) markers and six agronomic traits in field trials in 22 environments. Analysis of the yield, agronomic, and SNP data revealed 23 significant marker-trait associations for yield, 19 for maturity, 15 for plant height, 17 for plant lodging, and 29 for seed mass. A higher frequency of estimated positive yield alleles was evident from elite founder parents than from exotic founders, although unique desirable alleles from the exotic group were identified, demonstrating the value of expanding the genetic base of US soybean breeding

Deficient NRG1-ERBB signaling alters social approach: relevance to genetic mouse models of schizophrenia

Growth factor Neuregulin 1 (NRG1) plays an essential role in development and organization of the cerebral cortex. NRG1 and its receptors, ERBB3 and ERBB4, have been implicated in genetic susceptibility for schizophrenia. Disease symptoms include asociality and altered social interaction. To investigate the role of NRG1-ERBB signaling in social behavior, mice heterozygous for an Nrg1 null allele (Nrg1+/−), and mice with conditional ablation of Erbb3 or Erbb4 in the central nervous system, were evaluated for sociability and social novelty preference in a three-chambered choice task. Results showed that deficiencies in NRG1 or ERBB3 significantly enhanced sociability. All of the mutant groups demonstrated a lack of social novelty preference, in contrast to their respective wild-type controls. Effects of NRG1, ERBB3, or ERBB4 deficiency on social behavior could not be attributed to general changes in anxiety-like behavior, activity, or loss of olfactory ability. Nrg1+/− pups did not exhibit changes in isolation-induced ultrasonic vocalizations, a measure of emotional reactivity. Overall, these findings provide evidence that social behavior is mediated by NRG1-ERBB signaling

Virology under the microscope—a call for rational discourse

Viruses have brought humanity many challenges: respiratory infection, cancer, neurological impairment and immunosuppression to name a few. Virology research over the last 60+ years has responded to reduce this disease burden with vaccines and antivirals. Despite this long history, the COVID-19 pandemic has brought unprecedented attention to the field of virology. Some of this attention is focused on concern about the safe conduct of research with human pathogens. A small but vocal group of individuals has seized upon these concerns – conflating legitimate questions about safely conducting virus-related research with uncertainties over the origins of SARS-CoV-2. The result has fueled public confusion and, in many instances, ill-informed condemnation of virology. With this article, we seek to promote a return to rational discourse. We explain the use of gain-of-function approaches in science, discuss the possible origins of SARS-CoV-2 and outline current regulatory structures that provide oversight for virological research in the United States. By offering our expertise, we – a broad group of working virologists – seek to aid policy makers in navigating these controversial issues. Balanced, evidence-based discourse is essential to addressing public concern while maintaining and expanding much-needed research in virology

Temperature mooring data collected at Station AT55 in Lake Michigan from August 1, 2017 to April 20, 2018.

Dataset: Station AT55 Temperature mooring dataA fixed mooring was established to measure water column temperatures in Lake Michigan near Milwaukee, WI, from Aug 1 – Aug 17, 2017 at a 55 meters depth site and again during 2018 from April 5 – April 20, 2018. The mooring involved a large tripod to which a surface line was attached and along this line were temperature sensors at various depths. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/734541NSF Division of Ocean Sciences (NSF OCE) OCE-165839

Velocity observations from a mooring at Station AT55 in Lake Michigan from 2017-08-01 to 2017-08-16.

Dataset: ADCP Lake Michigan 2017A fixed mooring was established to measure water column velocities in Lake Michigan near Milwaukee (12 km northeast of Milwaukee Harbor), WI, during 2017 from Aug 1 – Aug 17, 2017 at a 55m depth site. The mooring involved a large tripod, upon which three velocimeters (Nortek Vector, Nortek Aquadopp HR profiler, Nortek Signature 500) were mounted to measure water column velocities between 13cm and 5139cm above the bed. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/856488NSF Division of Ocean Sciences (NSF OCE) OCE-165839