7696 research outputs found
Sort by
Environmental and evolutionary controls in animal-sediment interactions at the onset of the Cambrian explosion
No full textThe Cambrian explosion was a time of groundbreaking ecological shifts related to the establishment of the Phanerozoic biosphere. Trace fossils, which are the products of animals interacting with their substrates, provide a key record of the diversification of the benthos and the evolution of behavioral complexity through this interval. The Chapel Island Formation of Newfoundland in Canada hosts the most extensive trace-fossil record from the latest Ediacaran to Cambrian Age 2, spanning about 20 million years continuously. To elucidate the relative roles of environmental changes as opposed to evolutionary trajectories, we gathered the largest trace-fossil dataset to date and designed fourteen high-resolution time-environment matrices on bioturbation intensity, burrow width and depth, tiering (i.e., the vertical partitioning of trace fossils within the substrate), ichnodiversity, ichnodisparity (i.e., the development of novel architectural designs in ichnotaxa), ecospace utilization (i.e., the development of ecological niches by benthic animals), and other trends related to specific trace-fossil types. Ecosystem engineering by early animals resulted in three stages identified in the Chapel Island Formation that are probably global—an Ediacaran matground ecology, a Fortunian matground/firmground ecology, and a latest Fortunian/Cambrian Age 2 mixground ecology. Time-environment matrices further imply that the lower offshore was the cradle of diversification for animal behavior, which later expanded inshore and led to a novelty evolutionary event, refining our understanding of the early stages of the Cambrian explosion
A Postmodern Historical Novel Reimagines 15th-century East-West Politics: Vera Mutafchieva\u27s \u3ci\u3eThe Case of Cem\u3c/i\u3e, tr. from Bulgarian by Angela Rodel
No full text
Rats and mice rapidly update timed behaviors
No full textKeeping track of time intervals is a crucial aspect of behavior and cognition. Many theoretical models of how the brain times behavior make predictions for steady-state performance of well-learned intervals, but the rate of learning intervals in these models varies greatly, ranging from one-shot learning to learning over thousands of trials. Here, we explored how quickly rats and mice adapt to changes in interval durations using a serial fixed-interval task. In the first experiment, animals experienced randomly selected fixed-intervals of 12, 24, 36, 48, or 60 s, for blocks ranging from 13 to 21 trials. Consistent with previous work, animals abruptly increased lever pressing as reward availability approached, and these \u27start times\u27 scaled with the interval duration for both species. We then quantified the rate of updating to new trial durations and found that rodents consistently updated their start times within 2-3 trials following a change in interval duration, before stabilizing their behavior by the third or fourth trial. To account for repeated exposures to fixed-interval durations, a second set of animals was tested with new fixed-intervals after being trained on the serial fixed-interval task described above. Next, a third group was trained on fixed-interval durations that were generated de novo in each day. In each of these contexts, rodents rapidly increased or decreased their start times to mirror new FI durations following exposure to 1-2 trials of new intervals following block transitions. This work adds to growing evidence for rapid duration learning across species, highlighting the need for timing models to be capable of rapid updating in dynamic temporal scenarios
Building Communities of Practice among Undergraduate STEM Departments to Foster Emergent Transformation: A Report on the Impact of Multiple-year Engagement within the PULSE Midwest and Great Plains Regional Network
No full textA vibrant ecosystem of innovation hinges on undergraduate science programs that inclusively deepen conceptual understanding, develop scientific competencies, and spark wonder and appreciation for science. To create this ecosystem, we need to influence multiple components of the system, including faculty as well as culture (i.e., rules, goals, and beliefs giving rise to them). Here we describe and evaluate a multi-institution community of practice focused on transforming undergraduate biology programs\u27 organizational practices, behaviors, and beliefs, as well as instilling a sense of agency in community participants. The approach drew on three change theories: Community of Practice, Participatory Organizational Change, and Organizational Justice. Via mixed methods, we found that participation in the community catalyzed the flow of tangible capital (knowledge resources), grew social capital (relationships and identity), and developed human capital (creative problem-solving and facilitative leadership skills; sense of agency). In participants\u27 home departments, application of knowledge capital was associated with increased implementation of the principles of the Vision and Change report. Departmental change was enhanced when coupled with use of capitals developed through a community of practice centered on creative problem-solving, facilitative leadership, conflict resolution, and organizational justice
Borderlandia: The Art and Language of Chicanos as Exemplified in Enrique Chagoya’s Work
No full textMickey Mouse’s giant gloved hand hovers, poised to flick away a frightened young brown girl. In another piece, a Mexica-inspired deity stands face-to-face with the iconic Superman, dressed in recognizable pilgrim attire. These striking images are part of Enrique Chagoya’s Borderlandia exhibit. In Borderlands/La Frontera: The New Mestiza, Gloria Anzaldúa highlights the Chicano as a transformer of the Borderlands. Similarly, I explore the Chicano identity as a transformative force within the liminal space of Borderlandia. Because I was not introduced to English during my early developmental years, I—like many others—naturally blended my native language with English. However, I came to understand how this fusion, Spanglish, was denigrated—dismissed as “too ghetto,” uneducated, and a marker of poverty. My research examines how Spanglish and interconnected themes like Rasquachismo are visually represented in Chagoya’s work. Through his portrayal of Spanglish and the Borderlands, Chagoya juxtaposes symbols and imagery from both Mexican and American cultures, highlighting the multifaceted ways Chicanos navigate, express, and construct their identities. In this presentation, I analyze Chagoya’s accordion-style codex, drawing connections between Rasquachismo, Spanglish, and Anzaldúa’s theories. Through this exploration, I demonstrate how art and language function as powerful forms of resistance within the Borderlands, shaping and reclaiming Chicano cultural identity
Developing Scent Emitters to Investigate VOC-Mediated Insect Interactions
No full textVolatile organic compounds (VOCs) are molecules synthesized and emitted by plants into the nearby environment. They can serve as key signals in plant-plant communication, and as mediators for ecological interactions with pollinators and predators. The overall VOC scent profile of any plant is made up of a complex blend of dozens of VOCs, whose levels fluctuate with environmental stimuli. As a result, investigations into the role of any singular compound—whether it serves to attract pollinators, repel predators, recruit parasitoids of predators, or several of the above—have proven difficult.
Previous work in this lab has investigated the ecological importance of volatile organic compounds emitted by Castilleja sessiliflora, a hemiparasitic plant native to central and western North America that interacts with both predatory and pollinating insects. Using tobacco hornworms and adult hawkmoths (Manduca sexta) as a model, we seek to specifically examine the role of several ecologically important VOCs, such as the monoterpenoid linalool, in a lab setting. Currently, there is minimal published information on methods to artificially replicate plant-like VOC emission with singular, isolated compounds in vitro. Through the use of headspace VOC collection and GS-MS analysis, we are working to develop designs and protocols for VOC emission devices (“scent emitters”) that effectively mimic ecologically relevant emission patterns. These findings will help to lay foundations in methodology for future investigations into the role of VOCs in mediating insect interactions, both in a lab setting and as a resource for future field studies
Understanding the role of lactose, glucose, and galactose on the composition of E. coli extracellular polymeric substances and antibiotic sensitivity
No full textBiofilm is a complex matrix of bacterial cells and extracellular polymeric substances adopted by bacteria most commonly during periods of environmental stress. In this state, bacteria exhibit increased resistance to antibiotics. Documenting the influence of sugar metabolism on biofilm growth, composition, and antibiotic sensitivity provides useful insight into environmental conditions that exacerbate or prevent biofilm growth. Specifically, we focused on the impact of lactose, a non-phosphotransferase disaccharide which has a separate, controlled pathway for uptake into the bacterial cell, and its impacts on biofilm growth, composition, and antibiotic sensitivity in Escherichia coli (E. coli). Additionally, we investigated whether the two monosaccharide components of lactose, glucose and galactose, have similar impacts as lactose either collectively or independently. Crystal violet assays, staining of biofilm followed by confocal imaging, and growth of E. coli on agar plates followed by protein and carbohydrate assays allowed for biofilm growth and composition quantification. Additionally, disk diffusion and microbroth dilutions were carried out to determine the susceptibility of E. coli under differing growth conditions to several antibiotics. In the presence of lactose, and glucose and galactose, administered simultaneously and separately, E. coli susceptibility to multiple fluoroquinolones and macrolides decreased while susceptibility increased for an antimycobacterial agent. Ultimately, knowledge about the intersection and influence of sugar metabolism, biofilm formation and composition, and antibiotic susceptibility will lead to developments that disrupt biofilm formation or allow better control of biofilm-associated infections