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Plant phytochromes are well-studied photoreceptors that sense red and far-red light, regulating photomorpho- genic development. Molecular signaling mechanisms of phytochrome A (phyA) and phyB largely overlap, especially in regulation of PHYTOCHROME-INTERACTING FACTORs (PIFs) and E3 ligase complexes composed of CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and SUPPRESSORs OF phyA-105 (SPAs). However, the differences in their molecular signaling mechanisms remain unclear. Constitutively active mutants of phyB (YVB) and NLS-fused phyA (YVA:NLS) mediate light-independent seedling development, leading to constitutive photomorphogenic (cop) phenotypes in their transgenic Arabidopsis plants. Interestingly, YVB interacted with PIF3 independently of light, but YVA showed little interaction. In this study, we investigated distinct signaling mechanisms underlying the similar cop phenotypes given by YVB and YVA:NLS. Our findings indicated that YVA efficiently inactivate the COP1/SPA complex, leading to accumulation of ELONGATED HYPOCOTYL 5 (HY5) and subsequent expression of its target genes HY5 and HYH. YVB induced light-independent PIF3 and PIF1 degra- dation, in addition to HY5 accumulation. Moreover, co-expression of PIF3 in the YVB plant significantly attenuated the cop phenotypes, but minimal effects were observed in the YVA:NLS plant. In particular, PIF3 negatively regulated the interaction between YVB and COP1, which decreased HY5 accumulation in the YVB plant co-expressing PIF3. Furthermore, when transferred from light to dark, PIF3 was highly accumulated in phyB-5, whereas HY5 is degraded faster in phyA-201 compared to that in Ler. Collectively, our results suggest HY5 accumulation as the molecular bases for the cop phenotypes and also indicate that phyB is more important for regulating PIF3, whereas phyA effectively inactivates the COP1/SPA complex relative to PIF3 degradation. 

Context. The dust observed in debris disks is the result of a collisional cascade initiated from approximately kilometer-sized parent bodies. Using near-infrared to submillimeter observations, we can probe particle sizes spanning 2-3 orders of magnitude, and with sufficient angular resolution we can follow the dynamics of these dust particles. Observations taken as part of the ALMA survey to Resolve exoKuiper belt Substructures (ARKS) program allowed for a detailed comparison with near-infrared scattered light observations, at an unprecedented resolution. Aims. The comparison between the two wavelength regimes reveals that for most gas-bearing debris disks, the distribution of small dust grains peaks outside the distribution of large dust grains. In this paper, we investigate whether gas-dust interactions can explain such radial offsets. Methods. We performed numerical simulations that account for the effects of radiation pressure, gas drag, and collisions, and computed surface brightness profiles at several wavelengths to assess which parameters drive these radial offsets. We explored several families of models, varying the gas mass, disk optical depth, dust size distribution, and radiation pressure strength. Results. We find that while higher gas masses lead to more efficient outward radial drift, the resulting radial offset strongly depends on the optical depth of the disk, as the drift efficiency directly competes with the particles’ collisional lifetime. We also find that increasing the relative number of micron-sized dust grains usually yields a larger radial offset between scattered light and millimeter observations. Finally, we show that mid-infrared observations can complement near-infrared and submillimeter images, and we discuss the formation of secondary rings at near-infrared wavelengths. Conclusions. The angular resolution achieved by the ARKS program has opened a new avenue for studying the dynamics of dust particles in debris disks, revealing unexpected differences between the appearance of the disks scattered light and thermal emission. We show that gas-dust interactions can explain the observed radial offsets and provide pointers as to which parameters have the most significant impact. 

Context. Debris discs were long considered to be largely gas-free environments, where dynamical evolution is governed primarily by collisional fragmentation, gravitational stirring, and radiative forces. Recent detections of CO molecular line emission in debris discs demonstrate that gas is present, but its abundance and origin are still uncertain. TheALMA survey to Resolve exoKuiper belt Substructures (ARKS)observed both the gas and dust of several debris discs at high resolution and revealed a narrow ring of gas and dust in the disc HD 121617, with an asymmetric arc-like feature that is 40% brighter than the rest of the ring. Aims. An important open question is how representative the estimated CO masses are for the total gas mass in debris discs. We aim to constrain the total gas mass in HD 121617 using numerical models under the assumption that the dust arc is produced by hydrodynamical processes involving the gas. Methods. We used the hydrodynamical code Dusty FARGO-ADSG, in which dust is modelled as Lagrangian particles. We explored the effects of radiation pressure and dust feedback, as well as of varying the total gas mass on the dynamical evolution of the system. We compared these simulations with observations via radiative transfer calculations. Results. We find that an unstable gas ring can create a size-dependent radial and azimuthal dust trap. The total gas mass dictates the efficiency of particle trapping as a function of grain size. We find that two of our models,M_gas=50M_⊕andM_gas=5M_⊕, can simultaneously reproduce the observed arc in the ALMA band 7 continuum image and the radial outward offset of the VLT/SPHERE scattered light ring, driven by the combined effects of gas drag and radiation pressure. We further find a conservative lower limit ofM_gas>2.5M_⊕and a conservative upper limit ofM_gas<250M_⊕. Conclusions. If the ALMA band 7 asymmetry is caused by gas drag, reconciling the required gas mass with the observed¹²CO emission suggests the presence of significant amounts of H₂, consistent with the gas being primordial, that is, long-lived remnant material from the protoplanetary disc phase. In this scenario, HD 121617 would represent a hybrid disc, bridging the protoplanetary and debris disc stages. As an arc-shaped emission can alternatively be reproduced by a planet’s gravitational forcing, future observations are crucial to distinguish between these two scenarios. 

Context. Dusty discs detected around main-sequence stars are thought to be signs of planetesimal belts in which the dust distribution is shaped by collisional and dynamical processes, including interactions with gas if present. The debris disc around the young A-type star HD 131835 is composed of two dust rings at ∼65 au and ∼100 au, a third unconstrained innermost component, and a gaseous component centred at ∼65 au. New ALMA observations show that the inner of the two dust rings is brighter than the outer one, in contrast with previous observations in scattered light. Aims. We explore two scenarios that could explain these observations: the two dust rings might represent distinct planetesimal belts with different collisional properties, or only the inner ring might contain planetesimals while the outer ring consists entirely of dust that has migrated outwards due to gas drag. Methods. To explore the first scenario, we employed a state-of-the-art collisional evolution code. To test the second scenario, we used a simple dynamical model of dust grain evolution in an optically thin gaseous disc. In each case we identified the parameters of the planetesimal and the gaseous disc that best reproduce the observational constraints. Results. Collisional models of two planetesimal belts cannot fully reproduce the observations by only varying their dynamical excitation, and matching the data through a different material strength requires an extreme difference in dust composition. The gas-driven scenario can reproduce the location of the outer ring and the brightness ratio of the two rings from scattered light observations, but the resulting outer ring is too faint overall in both scattered light and sub-millimetre emission. Conclusions. The dust rings in HD 131835 could be produced from two planetesimal belts, although how these belts would attain the required extremely different properties needs to be explained. The dust-gas interaction is a plausible alternative explanation and deserves further study using a more comprehensive model. 

The Mechanical Engineering Department at a private, mid-sized university was awarded the National Science Foundation (NSF) Revolutionizing Engineering and Computer Science Departments (RED) grant in July 2017 to supports the development of a program that fosters students’ engineering identities in a culture of doing engineering with industry engineers. With a theme of strong connection to industry, through changes in four essential areas, a shared department vision, faculty, curriculum, and supportive policies, this culture of “engineering with engineers” is being cultivated. Many actions have taken to develop this culture. This paper reports our continued efforts in changes of these four areas: Shared department vision: The department worked together to revise the department mission to reflect the goal of fostering engineering identity. From this shared vision, the department updated the advising procedure and began addressing the challenge of diversity and inclusion faced in engineering. A diversity and inclusion statement was discussed by all faculty and included in all syllabi offered by the department to emphasize the importance of an inclusive culture. Faculty: The pandemic prompted faculty to think differently on how they deliver their courses and interact with students. Many faculty members adapted inverted classroom pedagogy and implemented remote laboratories to continue the emphasis of “doing engineering”. The industry adviser holds weekly virtual office hours to continue to provide industry contacts for students. Although faculty summer immersion this past year was postponed due to pandemic, interactions with industry were continued in various courses. Curriculum: A new mechanical engineering curriculum rolled out in the 2019-20 academic year. Although changes have to be made due to the pandemic but the focus of “engineering with engineers” remained. An example would be the Vertical Integrated Design Projects (VIDP) courses offered in Spring 2020. Utilizing virtual communication tools such as Microsoft Teams, student teams in the VIDP courses could still interact with industry advisors on a regular basis and learned from their experiences. Supportive policies: The department has worked closely with other departments, the college and the university to develop supportive policies. Recently, the college recommended the diversity and inclusion statement developed by the department to all senior design courses offered in the college. The university was aware of the goal of this project in fostering students’ engineering identities, which in term can promote the retention of URMs. The department’s effort is aligned with the new initiative the university launched to build an inclusive environment. More details of the action items in each area of change that the department has taken to build this culture of engineering with engineers will be shared in the full-length paper. This project was funded by the Division of Undergraduate Education (DUE) IUSE/PFE: RED grant through NSF. 

Finding tangible ways to incorporate inclusion into classroom environments remains a daunting task for many educators. The engineering education literature provides examples of activities to try and practices to incorporate, but applying the literature in a manner appropriately nuanced to an educator’s specific situated context takes time and effort. There are also many unknown factors educators cannot prepare for. In this narrative study, we present the story of an instructor who takes incremental steps to build an inclusive environment in a senior capstone course in order to promote her student’s understanding of the importance of having an inclusive environment. This paper highlights how one new tool, the Inclusivity Meter (IM), produces insights for the department as it continues its Revolutionizing Engineering Departments (RED) grant. Despite various changes incorporated in the senior design and the department as a whole, students continued to bring up feelings of exclusion in departmental and college wide surveys, which warranted further attention. This study documents one quarter, Fall of 2020, as the school continues with virtual learning during the COVID-19 pandemic. The tool, the “Inclusivity Meter,” is a weekly reflection activity that asks students to answer two questions: “How included did you feel?” and “Are there any additional comments you would like to add?”. Each senior design team was required to formulate team norms and a team agreement to scaffold the conversations of inclusion. The instructor herself then reflected on these weekly enactments of the tool and becomes more aware of inclusion in her classroom and what conversations seem to bubble up around the Inclusivity Meter.She also reflects on how this practice communicates to her students her commitment to inclusion and how it has helped her encourage students to speak up about issues around inclusion. Here, we monitor this practice through a series of reflective conversations between the educator and the other two authors and present a narrative based on themes from these conversations. This study provides new engineering educators an insight into what it looks like to incorporate a specific inclusive practice, how we might start thinking differently about what works and for whom in enacting inclusive practices, and how educators can continue to develop their “integrity of practice” around inclusion. 

Background. While educational change often involves bold talk about disruptive ideas that eventually need to be institutionalized, a critical but often less visible element of sustaining change is work such as maintaining a shared vision, onboarding new people, negotiating small issues in light of department culture, and coordinating big changes with existing efforts. While knowledge about these forms of invisible work exist in other disciplines, these issues seem understudied in engineering education. This work approaches this issue of invisible knowledge with a design orientation, and specifically draws on the field of design-based research. Increasingly, design is recognized as a knowledge producing activity, resulting in insights into generative ways of defining problems, frameworks for generating solutions to problems, examples of what it looks like to connect theory to specific problems. Purpose: As a design effort, this work asks: How might a specific department create a sustainable practice to support the invisible work of coordinating and sustaining change? As a scholarly effort, this instance of design can result in a culminating problem definition, a solution framework, and examples of theory use that represent knowledge contributions. Approach: A mechanical engineering department in a small, private educational institution worked for four months to develop a sustainable practice to support invisible work of coordinating and sustaining change. Following an initial commitment of 60 minutes once every three weeks and 3-hour retreat to explore possibilities, the department then iteratively designed and then carried out sample conversations. Each iteration involved specifying the goals of the conversation, how to have the conversation (the design) and the rationale for connecting the design to the goals. Traces from the process represent the data for this work. Results. Over time, the conversations came to be designed along four dimensions: topic, time allocation, turn-taking, and traces. We have learned that topics that are of immediate relevance to everyone are particularly powerful (initial topics included "being back on campus" and "navigating in-person"). We are currently leveraging a time allocation that devotes the most time to hearing from each participant on the topic, then time for the group to cautiously explore synthesis, and finally time for the group to weigh in on future conversation topics. Approaches to turn-taking have involved decentralization (e.g., each current speaker invites the next speaker) and respect (speakers have a chance to "pass" and then choose the next speaker). Finally, we are experimenting with how to balance the creation of traces as a natural part of the process, such as through real-time transcription in the chat feature of zoom. Undergirding each of these dimensions are connections to the intended goals, connections to relevant theory, and connections to the long-term goal of sustainability. In presenting these ideas, we will focus on how the information being offered connects to the current body of knowledge in engineering education. Conclusion. It is promising to treat the work of department culture as a design problem. The ideas in this framework may serve as inspiration to others seeking to create their own sustainable mechanisms but with different conditions. During the winter and spring of 2022, the approach will be additionally tested via six deployments, and insights will be shared in subsequent publications. 

The Mechanical Engineering Department at a private, mid-sized university was awarded the National Science Foundation (NSF) Revolutionizing Engineering and Computer Science Departments (RED) grant in July 2017 to support the development of a program that fosters students’ engineering identities in a culture of doing engineering with industry engineers. The Department is cultivating this culture of “engineering with engineers” through a strong connection to industry, and through changes in the four essential areas of, a shared department vision, faculty, curriculum and supportive policies. This paper reports our continued efforts in these four areas and our measurement of their impact. Shared department vision: During the first year of the project, the department worked together to revise its mission to reflect the goal of fostering engineering identity. From this shared vision, the department aims to build a culture to promote inclusive practices. In the past year during the COVID-19 pandemic, this shared vision continued to guide many acts of care and community building for the department. Faculty: The pandemic prompted faculty to reflect on how they delivered their courses and cared for students. To promote inclusive practice, faculty utilized recorded lectures, online collaboration tools and instant messaging apps to provide multiple ways of communication for students. Although faculty summer immersion had to be postponed due to pandemic, interactions with industry continued in design courses, and via virtual seminars and socials. Efforts were also extended to strengthen connections between the department and recent graduates who just began working in industry and could become mentors for current students. Curriculum: A new curriculum to support the goals of this project was rolled out in the 2019-20 academic year. The pandemic hit right in the middle of the initial implementation of this new curriculum. Therefore, to maintain the essence of the new curriculum that emphasizes hands-on, doing engineering and experiential learning in the remote setting, many adjustments and modifications were made. Although initial evidence indicates the effectiveness of the new courses/curriculum even under remote teaching and learning, there are also many lessons-learned that can be examined for future implementations and modifications of the curriculum. Supportive policies: The department agreed to celebrate various acts of care for students and cares for teaching and learning in Annual Performance Reviews. Faculty also worked with other departments, the college, and the university to develop supportive policies beyond the department. For example, based on the recommendation from the department, the college set up a Student Advocate role who would assist students navigate through any incident that make they feel excluded. The new university tenure and promotion guidelines have just been approved with the support from the faculty in the department. Additionally, the department’s effort of building an inclusive culture is aligned with the university initiative for a reform to emphasize anti-racism curriculum. Details of the action items in each area of change that the department has taken to build this inclusive culture to foster engineering identity are shared in this paper. In addition, research gauging the impact of our efforts are discussed. This project was funded by the Division of Undergraduate Education (DUE) IUSE/PFE: RED grant through NSF.