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The stability of low-index platinum surfaces and their electronic properties is investigated with density functional theory, toward the goal of understanding the surface structure and electron emission, and identifying precursors to electrical breakdown, on nonideal platinum surfaces. Propensity for electron emission can be related to a local work function, which, in turn, is intimately dependent on the local surface structure. The $(1\ifmmode\times\else\texttimes\fi{}N)$ missing row reconstruction of the Pt(110) surface is systematically examined. The $(1\ifmmode\times\else\texttimes\fi{}3)$ missing row reconstruction is found to be the lowest in energy, with the $(1\ifmmode\times\else\texttimes\fi{}2)$ and $(1\ifmmode\times\else\texttimes\fi{}4)$ slightly less stable. In the limit of large $(1\ifmmode\times\else\texttimes\fi{}N)$ with wider (111) nanoterraces, the energy accurately approaches the asymptotic limit of the infinite Pt(111) surface. This suggests a local energetic stability of narrow (111) nanoterraces on free Pt surfaces that could be a common structural feature in the complex surface morphologies, leading to work functions consistent with those on thermally grown Pt substrates.

Background: Design-based research frameworks have become more widely embraced by education researchers since 2003. Ann Brown (1992) first suggested design-based research as a means to move research about learning from the laboratory to the classroom setting. Design-based research does not imply particular methods, but rather is an epistemological approach to carrying out research projects focused on the design of an innovation. This shift in epistemological outcome shifts how researchers consider evidence gathering and analysis. So how are engineering education researchers using and reporting on design-based research? Purpose: The design of educational innovations should be situated in context and balance both theory and practice. In this paper, we summarize research in engineering education that has used a design-based research approach. We first describe design-based research from a theoretical and epistemological perspective and then present its use thus far in engineering education settings. Our goal is to suggest it as a useful model for undertaking engineering education research that advances knowledge about the design of learning environments. Scope: Our analysis is situated in significant features of design-based research (Kelly, 2004; Sandoval, 2014). Our review process began with systematically searching for articles and then coding them for the features of design-based research. We have coded a set of engineering education and design-based research articles to summarize the contexts, conjectures, and design cycles. Discussion/Conclusions: We found articles across K–12 and higher education settings. The articles focused on designing models and tools for engineering education including curriculum, tasks, and frameworks. First, design-based research in engineering education includes conjectures about engineering disciplinary practices, problem-based learning, and affective aspects of students’ learning. Second, cycles of design inform improvement and theory development. Design-based research is still emerging in engineering education but has potential for building knowledge and developing resources grounded in practice.

Aims: Growth hormone (GH) therapy in heart failure (HF) is controversial. We investigated the cardiovascular effects of GH in patients with chronic HF due to ischemic heart disease. Methods: In a double-blind, placebo-controlled trial, we randomly assigned 37 patients (mean age 66 years; 95% male) with ischemic HF (ejection fraction [EF] < 40%) to a 9-month treatment with either recombinant human GH (1.4 mg every other day) or placebo, with subsequent 3-month treatment-free follow-up. The primary outcome was change in left ventricular (LV) end-systolic volume measured by cardiac magnetic resonance (CMR). Secondary outcomes comprised changes in cardiac structure and EF. Prespecified tertiary outcomes included changes in New York Heat Association (NYHA) functional class and quality of life (QoL), as well as levels of insulin-like growth factor-1 (IGF-1) and N-terminal pro-brain natriuretic peptide (NT-proBNP). Results: No changes in cardiac structure or systolic function were identified in either treatment group; nor did GH treatment affect QoL or functional class. In the GH group, circulating levels of IGF-1 doubled from baseline (+105%; p < 0.001) and NT-proBNP levels halved (−48%; p < 0.001) during the treatment period, with subsequently a partial return of both towards baseline levels. No changes in IGF-1 or NT-proBNP were observed in the placebo group at any time during the study. Conclusion: In patients with chronic ischemic HF, nine months of GH treatment was associated with significant increases in levels of IGF-1 and reductions in levels of NT-proBNP, but did not affect cardiac structure, systolic function or functional capacity.

Structural disorder causes materials’ surface electronic properties, e.g., work function ([Formula: see text]), to vary spatially, yet it is challenging to prove exact causal relationships to underlying ensemble disorder, e.g., roughness or granularity. For polycrystalline Pt, nanoscale resolution photoemission threshold mapping reveals a spatially varying [Formula: see text] eV over a distribution of (111) vicinal grain surfaces prepared by sputter deposition and annealing. With regard to field emission and related phenomena, e.g., vacuum arc initiation, a salient feature of the [Formula: see text] distribution is that it is skewed with a long tail to values down to 5.4 eV, i.e., far below the mean, which is exponentially impactful to field emission via the Fowler–Nordheim relation. We show that the [Formula: see text] spatial variation and distribution can be explained by ensemble variations of granular tilts and surface slopes via a Smoluchowski smoothing model wherein local [Formula: see text] variations result from spatially varying densities of electric dipole moments, intrinsic to atomic steps, that locally modify [Formula: see text]. Atomic step-terrace structure is confirmed with scanning tunneling microscopy (STM) at several locations on our surfaces, and prior works showed STM evidence for atomic step dipoles at various metal surfaces. From our model, we find an atomic step edge dipole [Formula: see text] D/edge atom, which is comparable to values reported in studies that utilized other methods and materials. Our results elucidate a connection between macroscopic [Formula: see text] and the nanostructure that may contribute to the spread of reported [Formula: see text] for Pt and other surfaces and may be useful toward more complete descriptions of polycrystalline metals in the models of field emission and other related vacuum electronics phenomena, e.g., arc initiation.

This article brings together the results of a self-study conducted by two instructors of the same course for mathematics teacher leaders in a synchronous online learning environment using the videoconferencing tool Blackboard Collaborate. The combined self-study focused on the authors' instructional decision-making and on their use of scaffolded discourse to create a collaborative learning environment for teacher leaders in mathematics education. Findings indicate that two specific interactions were emphasized to highlight student engagement within the course: student-student interactions and student-content interactions. Results challenge the perception of participation as engagement and suggest the value of creating purposefully planned learning opportunities to engage students in online synchronous learning.

The Odin satellite is now into its twentieth year of operation, much surpassing its design life of two years. One of its major pursuits was the search for and study of H2O in the Solar System and the Milky Way galaxy. Herschel has observed the central region of NGC 1365 in two positions, and both its SPIRE and PACS observations are available in the Herschel Science Archive. Herschel PACS images have been produced of the 70 and 160 micron infrared emission from the whole galaxy, and also of the cold dust distribution as obtained from the ratio of the 160 to 70 micron images. The Herschel SPIRE observations have been used to produce maps of the 557 GHz o-H2O, 752 GHz p-H2O, 691 GHz CO(6-5), 1037 GHz CO(9-8), 537 GHz CH, 835 GHz CH+, and the 1461 GHz NII lines; however, these observations have no effective velocity resolution. Odin has recently observed the 557 GHz o-H2O ground state line in the central region with high (5 km/s) spectral resolution. The emission and absorption of H2O at 557 GHz, with a velocity resolution of 5 km/s, has been marginally detected in NGC 1365 with Odin. The H2O is predominantly located in a shocked 15" (1.3 kpc) region near some central compact radio sources and hot-spot HII regions, close to the northeast component of the molecular torus surrounding the nucleus. An analysis of the H2O line intensities and velocities indicates that a shock-region is located here. This is corroborated by a statistical image deconvolution of our SEST CO(3-2) observations, yielding 5" resolution, and a study of our VLA HI absorption observations. Additionally, an enticing 20" HI ridge is found to extend south-southeast from the nucleus, coinciding in position with the southern edge of an OIII outflow cone, emanating from the nucleus. The molecular chemistry of the shocked central region is analyzed with special emphasis on the CO, H2O and CH, CH+ results., Comment: 25 pages, 11 figures

In July 1994, comet Shoemaker-Levy 9 collided with Jupiter. This has introduced new chemical species into Jupiter’s atmosphere, notably H2O. We observed the disk-averaged emission H2O in Jupiter’s stratosphere at 556.936 GHz between 2002 and 2019 with the Odin space telescope with the initial goal of better constraining vertical eddy mixing (Kzz) in the layers probed by our observations (0.2-5 mbar). The Odin observations show a decrease of about 40% of the line emission from 2002 to 2019. We analyzed these observations by combining a 1D photochemical model with a radiative transfer model to constrain the vertical eddy diffusion Kzz in the stratosphere of Jupiter. We were able to reproduce this decrease by modifying a well-established Kzz profile, in the 0.2 mbar to 5 mbar pressure range. However, the Kzz obtained is incompatible with observations of the main hydrocarbons. We found that even if we increase locally the initial abundances of H2O and CO at impact, the photochemical conversion of H2O and CO to CO2 does not allow us to find the observed decrease of the H2O emission line over time, suggesting that there is another loss mechanism. We propose that auroral chemistry, not accounted for in our model, as a promising candidate to explain the loss of H2O seen by Odin. Modeling the temporal evolution of the chemical species deposited by comet SL9 in the atmosphere of Jupiter with a 2D photochemical model would be the next step in this study.

GTAs have significant teaching and learning responsibilities in many highly enrolled undergraduate STEM courses at Mason. They serve as recitation instructors, laboratory instructors, tutors (via office hours), and graders. In these roles, GTAs can have a significant impact on undergraduate students’ learning experience. Hence, mentoring GTAs as they develop and refine their teaching skills is critical to the success of our undergraduate STEM programs. That said, traditionally there has been little investment in formal GTA training beyond the department level at Mason. A variety of models for STEM GTA training have been described in existing literature. Proposed models often take the form of intensive summer institutes (e.g., Rivera, 2018; Dragisich, 2016) that are one to two weeks in length. A study of successful calculus programs noted that the most effective GTA training models associated with these programs included either a summer session with follow-up during the year or a semester-long course on teaching (Rasmussen, 2014), suggesting that ongoing teaching professional development is an important factor in successful GTA training. As part of an existing NSF-funded project we are working to increase the use of student-centered learning in highly enrolled courses. The first two departments engaged in this effort have initially focused on increasing student-centered learning in GTA-led aspects of the targeted courses, e.g. recitations and labs. Targeting GTA-led efforts has been viewed as easier because GTA training (which was not already in place) is fairly easy to create and because GTAs are viewed as more willing than their faculty counterparts to change the way they teach. Additionally, recitations and labs tend to occur in smaller groups, so they provide the opportunity for more hands-on engagement with course material and are natural places to begin a movement toward active learning. Hence, a first step toward transforming highly enrolled courses is providing the necessary professional development for GTAs. Physics and Math, the initial departments engaged in this project, have created and refined their own structures for ongoing GTA development, each catering to the culture and specific needs of their own department. Our goals for this roundtable discussion are: (1) to share GTA training models that have been adopted in several STEM departments at Mason, including curriculum for the professional development sessions, structure of sessions (GTA vs. faculty-led), mechanisms for GTA buy-in, and challenges encountered in developing these professional development opportunities including differing needs of new and experienced GTAs; and (2) to learn about other models of GTA training at Mason, identify the needs of departments and faculty in training their GTAs, and to identify elements of GTA professional development that can be shared across departments and potentially institutionalized., Innovations in Teaching & Learning Conference Proceedings, Vol. 12 (2020): Teaching Towards the Future

Want to talk about one of the On Demand pre-recorded sessions with the authors and other colleagues? Join us for this informal session in which the authors will play the pre-recorded video for everyone to watch together and then open the rest of the time up for discussion. This Watch Party is about Teaching Professional Development for STEM GTAs. GTAs have significant teaching and learning responsibilities in many highly enrolled undergraduate STEM courses at Mason. They serve as recitation instructors, laboratory instructors, tutors (via office hours), and graders. In these roles, GTAs can have a significant impact on undergraduate students’ learning experience. Hence, mentoring GTAs as they develop and refine their teaching skills is critical to the success of our undergraduate STEM programs. That said, traditionally there has been little investment in formal GTA training beyond the department level at Mason. A variety of models for STEM GTA training have been described in existing literature. Proposed models often take the form of intensive summer institutes (e.g., Rivera, 2018; Dragisich, 2016) that are one to two weeks in length. A study of successful calculus programs noted that the most effective GTA training models associated with these programs included either a summer session with follow-up during the year or a semester-long course on teaching (Rasmussen, 2014), suggesting that ongoing teaching professional development is an important factor in successful GTA training. As part of an existing NSF-funded project we are working to increase the use of student-centered learning in highly enrolled courses. The first two departments engaged in this effort have initially focused on increasing student-centered learning in GTA-led aspects of the targeted courses, e.g. recitations and labs. Targeting GTA-led efforts has been viewed as easier because GTA training (which was not already in place) is fairly easy to create and because GTAs are viewed as more willing than their faculty counterparts to change the way they teach. Additionally, recitations and labs tend to occur in smaller groups, so they provide the opportunity for more hands-on engagement with course material and are natural places to begin a movement toward active learning. Hence, a first step toward transforming highly enrolled courses is providing the necessary professional development for GTAs. Physics and Math, the initial departments engaged in this project, have created and refined their own structures for ongoing GTA development, each catering to the culture and specific needs of their own department. Our goals for this roundtable discussion are: (1) to share GTA training models that have been adopted in several STEM departments at Mason, including curriculum for the professional development sessions, structure of sessions (GTA vs. faculty-led), mechanisms for GTA buy-in, and challenges encountered in developing these professional development opportunities including differing needs of new and experienced GTAs; and (2) to learn about other models of GTA training at Mason, identify the needs of departments and faculty in training their GTAs, and to identify elements of GTA professional development that can be shared across departments and potentially institutionalized., Innovations in Teaching & Learning Conference Proceedings, Vol. 12 (2020): Teaching Towards the Future

Utilizing James C. Scott’s germinal concept of everyday resistance, we examine the subtle, daily acts of resistance carried out by Mexican and Jamaican migrant farmworkers in the Okanagan Valley, British Columbia. We argue that despite finding themselves in situations of formidable constraint, migrant farmworkers utilize a variety of “weapons of the weak” that undermine the strict regulation of their employment by employers and state authorities. We also argue that everyday forms of resistance are important political acts and as such, they warrant inclusion in scholarly examinations. Indeed, by reading these methods neither as “real” resistance nor as political, we risk reproducing the same systems of power that de-legitimize the actions, agency, and political consciousness of subaltern and oppressed peoples. After a brief discussion on the concept of everyday resistance, we provide an overview of Canada’s Seasonal Agricultural Worker Program (SAWP), establishing the conditions that drive migrant workers to resist and drawing connections between the regulatory framework of the SAWP, the informality of the agricultural sector, and migrant labor. Finally, we examine specific instances of resistance that we documented over 3 recent years through ethnographic fieldwork and as community organizers with a grassroots migrant justice organization. We assert the importance of situating migrants’ everyday acts of resistance at the center of conceptualizations of the broader movement for migrant justice in Canada and worldwide.