arXiv subjects

Charles Henderson

Publications and source records attributed to Charles Henderson.

At least 19 recordsLinked to original sources

arXiv2026

The meaning of closeness to women and/or LGBTQ+ physicists: a social network analysis

'Closeness' is well-defined as a quantitative measure of centrality in social network analysis (SNA), but it is not as well defined qualitatively as a description of social relationships. This paper presents a qualitative analysis of 'closeness' as it is defined both implicitly and explicitly in interviews with 100 women and/or LGBTQ+ PhD physicists. The interviews include a social network construction component, and we define a quantitative network parameter that serves as a proxy for closeness, which we examine in relation to attributes of network members. We find that physicists in this sample see trust, relaxed boundaries, reliance, and support as concepts that most directly define closeness in their relationships. Consistent interaction, positive affect, and commonalities are also often present in (and in some cases, defining of) these relationships. From the quantitative analysis, we find that these physicists tend to view family and partners, friends, and professional friends as comprising their closest relationships. These results are consistent with other studies which have sought to define closeness qualitatively, but the prevalence of trust in this dataset in particular suggests that these physicists see the ability to confide as uniquely important in their relationships. We make recommendations to institutions supporting and employing physicists on how to better support gender and sexual minority (GSM) physicists going forward, and we believe these results help us gain a better understanding of how GSM physicists find success in physics despite the barriers they face due to their identities.

physics.soc-ph↗

arXiv2025

Unique support from identity-based groups: Professional networks of women and LGBTQ+ physicists analyzed and compared by career sector

This paper presents a social network analysis of the professional support networks of 100 LGBTQ+ and/or women PhD physicists, comparing the networks based on the career sectors of academia, industry, and government/nonprofit. The methods for constructing and analyzing the ego networks, which are novel in many ways, are explained in greater detail in an earlier publication (Hatcher et. al., 2025). We describe the networks of the whole group and use statistical tests of independence to explore differences between sectors in terms of whole network metrics, network composition based on alter (network member) characteristics, and support. We find that alters associated with groups (like affinity groups and personal and professional interest groups) are more likely to provide identity-based and community building support, participants in Academia have fewer personal friends in their networks while those in Industry have more, participants in Government report less instrumental support, and those in Academia report less material support. These results and others lead to suggestions for employers in these sectors on how to better support these physicists, including continuing to promote participation in affinity and interest groups, providing more material support and/or personal time in the academic sector, and more instrumental support in the form of professional development or training in the government sector.

physics.ed-ph↗

arXiv2025

Egocentric Mixed-Methods SNA: Analyzing Interviews with Women and/or LGBTQ+ Ph.D. Physicists

Social network analysis (SNA) has been widely used in physics education research (PER) in recent years, but mostly in a limited range of the available modalities. This paper describes a unique approach to egocentric, mixed-methods SNA applied to qualitative network data obtained from 100 interviews with women and/or queer professional physicists. We focus on our methods for obtaining quantitative network data from these qualitative sources and present novel techniques for analysis of the networks. We also examine the ways in which egocentric and mixed-methods SNA techniques are aligned with critical methods and well-suited to the study of difference, non-normativity, and experiences of marginalization in physics spaces and communities. We explore the limitations and potential applications of these methods and situate this work in the larger context of our study of these interviews. This work bridges a methodological gap between SNA and qualitative work on identity in PER and begins to develop our understanding of the way gender and sexual minority physicists experience support.

physics.ed-ph↗

arXiv2024

Person-centered and qualitative approaches to network analysis in physics education research

Network analysis has become a well-recognized methodology in physics education research (PER), with study topics including student performance and persistence, faculty change, and the structure of conceptual networks. The social network analysis side of this work has focused on quantitative analysis of whole-network cases, such as the structure of networks in single classrooms. Egocentric or personal network approaches are largely unexplored, and qualitative methods are underdeveloped. In this paper, we outline theoretical and practical differences between two major network paradigms--whole-network and egocentric--and introduce theoretical frameworks and methodological considerations for egocentric studies. We also describe qualitative and mixed-methods approaches that are currently missing from the PER literature. We identify areas where these additional network methods may be of particular interest to physics education researchers, and end by discussing example cases and implications for new PER studies.

physics.ed-ph↗

arXiv2023

Knowledge Engineering for Wind Energy

With the rapid evolution of the wind energy sector, there is an ever-increasing need to create value from the vast amounts of data made available both from within the domain, as well as from other sectors. This article addresses the challenges faced by wind energy domain experts in converting data into domain knowledge, connecting and integrating it with other sources of knowledge, and making it available for use in next generation artificially intelligent systems. To this end, this article highlights the role that knowledge engineering can play in the process of digital transformation of the wind energy sector. It presents the main concepts underpinning Knowledge-Based Systems and summarises previous work in the areas of knowledge engineering and knowledge representation in a manner that is relevant and accessible to domain experts. A systematic analysis of the current state-of-the-art on knowledge engineering in the wind energy domain is performed, with available tools put into perspective by establishing the main domain actors and their needs and identifying key problematic areas. Finally, guidelines for further development and improvement are provided.

cs.AI↗

arXiv2022

Physics instructors knowledge and use of active learning has increased over the last decade but most still lecture too much

A survey of 722 physics faculty conducted in 2008 found that many physics instructors had knowledge of research-based instructional strategies (RBISs), were interested in using more, but often discontinued use after trying. Considerable effort has been made during the decade following 2008 to develop and disseminate RBISs in physics as well as change the culture within the physics community to value RBISs use and other forms of student-centered instruction. This paper uses data from a 2019 survey of 1176 physics instructors to understand the current state of RBIS use in college-level introductory physics, thus allowing us to better understand some of the impacts of these efforts on physics instruction. Results show that self-reported knowledge and use of RBISs has increased considerably and discontinuation is now relatively low. However, although the percentage of time lecturing is less than 10 years ago, many instructors still engage in substantial lecturing. Relatedly, we find that the majority of RBIS use centers on pedagogies designed to supplement traditional lecture rather than pedagogies designed to supplement an active learning classroom. This suggests that the PER community and beyond has done well promoting knowledge about RBISs and inspiring instructors to try RBISs in their courses. But, there is still room to improve. We recommend that change agents focus on supporting instructors to increase the percent of class time in active learning and to implement higher impact strategies.

physics.ed-ph↗

arXiv2022

Network analysis approach to Likert-style surveys

Likert-style surveys are a widely used research instrument to assess respondents' preferences, beliefs, or experiences. In this paper, we propose and demonstrate how network analysis (NA) can be employed to model and evaluate the interconnectedness of items in Likert-style surveys. We explore the advantages of this approach by applying the methodology to the aspects of student experience scale datasets and compare the results to the principal component analysis. We successfully create a meaningful network based on survey item response similarity and use modular analysis of the network to identify larger themes built from the connections of particular aspects. The modular NA of the network of survey items identifies important themes that highlight differences in students' overall experiences. Our network analysis for Likert-style surveys methodology is widely applicable and provides a new way to investigate phenomena assessed by Likert-style surveys.

physics.ed-ph↗

arXiv2021

The challenges of changing teaching assistants' grading practices: Requiring students to show evidence of understanding

Teaching assistants (TAs) are often responsible for grading in introductory physics courses at large research universities. Their grading practices can shape students' approaches to problem solving and learning. Physics education research recommends grading practices that encourage students to provide evidence of understanding via explication of the problem-solving process. However, TAs may not necessarily grade in a manner that encourages students to provide evidence of understanding in their solutions. Within the context of a semester-long TA professional development course, we investigated whether encouraging TAs to use a grading rubric that appropriately weights the problem-solving process and having them reflect upon the benefits of using such a rubric prompts TAs to require evidence of understanding in student solutions. We examined how the TAs graded realistic student solutions to introductory physics problems before they were provided a rubric, whether TAs used the rubric as intended, whether they were consistent in grading similar solutions, and how TAs' grading criteria changed after discussing the benefits of a well-designed rubric. We find that many TAs typically applied the rubric consistently when grading similar student solutions but did not require students to provide evidence of understanding. TAs' written responses, class discussions, and individual interviews suggest that the instructional activities involving the grading rubrics in this study were not sufficient to change their grading practices. Interviews and class discussions suggest that helping TAs value a rubric that appropriately weights the problem-solving process may be challenging partly due to the TAs past educational experiences and the departmental context.

physics.ed-ph↗

arXiv2019

WIRC+Pol: a low-resolution near-infrared spectropolarimeter

WIRC+Pol is a newly commissioned low-resolution (R~100), near-infrared (J and H band) spectropolarimetry mode of the Wide-field InfraRed Camera (WIRC) on the 200-inch Hale Telescope at Palomar Observatory. The instrument utilizes a novel polarimeter design based on a quarter-wave plate and a polarization grating (PG), which provides full linear polarization measurements (Stokes I, Q, and U) in one exposure. The PG also has high transmission across the J and H bands. The instrument is situated at the prime focus of an equatorially mounted telescope. As a result, the system only has one reflection in the light path, providing minimal telescope induced polarization. A data reduction pipeline has been developed for WIRC+Pol to produce linear polarization measurements from observations. WIRC+Pol has been on-sky since February 2017. Results from the first year commissioning data show that the instrument has a high dispersion efficiency as expected from the polarization grating. We demonstrate the polarimetric stability of the instrument with RMS variation at 0.2% level over 30 minutes for a bright standard star (J = 8.7). While the spectral extraction is photon noise limited, polarization calibration between sources remain limited by systematics, likely related to gravity dependent pointing effects. We discuss instrumental systematics we have uncovered in the data, their potential causes, along with calibrations that are necessary to eliminate them. We describe a modulator upgrade that will eliminate the slowly varying systematics and provide polarimetric accuracy better than 0.1%.

astro-ph.IM↗

arXiv2018

The Wide Integral Field Infrared Spectrograph: Commissioning Results and On-sky Performance

We have recently commissioned a novel infrared ($0.9-1.7$ $μ$m) integral field spectrograph (IFS) called the Wide Integral Field Infrared Spectrograph (WIFIS). WIFIS is a unique instrument that offers a very large field-of-view (50$^{\prime\prime}$ x 20$^{\prime\prime}$) on the 2.3-meter Bok telescope at Kitt Peak, USA for seeing-limited observations at moderate spectral resolving power. The measured spatial sampling scale is $\sim1\times1^{\prime\prime}$ and its spectral resolving power is $R\sim2,500$ and $3,000$ in the $zJ$ ($0.9-1.35$ $μ$m) and $H_{short}$ ($1.5-1.7$ $μ$m) modes, respectively. WIFIS's corresponding etendue is larger than existing near-infrared (NIR) IFSes, which are mostly designed to work with adaptive optics systems and therefore have very narrow fields. For this reason, this instrument is specifically suited for studying very extended objects in the near-infrared such as supernovae remnants, galactic star forming regions, and nearby galaxies, which are not easily accessible by other NIR IFSes. This enables scientific programs that were not originally possible, such as detailed surveys of a large number of nearby galaxies or a full accounting of nucleosynthetic yields of Milky Way supernova remnants. WIFIS is also designed to be easily adaptable to be used with larger telescopes. In this paper, we report on the overall performance characteristics of the instrument, which were measured during our commissioning runs in the second half of 2017. We present measurements of spectral resolving power, image quality, instrumental background, and overall efficiency and sensitivity of WIFIS and compare them with our design expectations. Finally, we present a few example observations that demonstrate WIFIS's full capability to carry out infrared imaging spectroscopy of extended objects, which is enabled by our custom data reduction pipeline.

astro-ph.IM↗

arXiv2017

Graduate teaching assistants use different criteria when grading introductory physics vs. quantum mechanics problems

Physics graduate teaching assistants (TAs) are often responsible for grading. Physics education research suggests that grading practices that place the burden of proof for explicating the problem solving process on students can help them develop problem solving skills and learn physics. However, TAs may not have developed effective grading practices and may grade student solutions in introductory and advanced courses differently. In the context of a TA professional development course, we asked TAs to grade student solutions to introductory physics and quantum mechanics problems and explain why their grading approaches were different or similar in the two contexts. TAs expected and rewarded reasoning more frequently in the QM context. Our findings suggest that these differences may at least partly be due to the TAs not realizing that grading can serve as a formative assessment tool and also not thinking about the difficulty of an introductory physics problem from an introductory physics student's perspective.

physics.ed-ph↗

arXiv2017

Physics graduate teaching assistants' beliefs about a grading rubric: Lessons learned

Explication and reflection on expert vs. novice considerations within the problem-solving process characterize a cognitive apprenticeship approach for the development of expert-like problem solving practices. In the context of grading, a cognitive apprenticeship approach requires that instructors place the burden of proof on students, namely, that they require explanations of reasoning and explication of problem-solving processes. However, prior research on instructors' considerations when grading revealed their reluctance to use such a grading approach, motivated by a perception of teaching that places the burden of proof on the instructor. This study focuses on physics graduate teaching assistants (TAs) who play a central role in grading. A short professional development activity was designed that involved eliciting TAs' perceptions regarding grading, presenting a cognitive apprenticeship-inspired grading rubric, followed by a discussion of the dilemma between placing the burden of proof on the instructor vs. the student. In this context, we examined TAs' grading considerations and approaches towards grading and the effect of the short professional development grading activity on them.

physics.ed-ph↗

arXiv2016

Teaching assistants' beliefs regarding example solutions in introductory physics

As part of a larger study to understand instructors' considerations regarding the learning and teaching of problem solving in an introductory physics course, we investigated beliefs of first-year graduate teaching assistants (TAs) regarding the use of example solutions in introductory physics. In particular, we examine how the goal of promoting expert-like problem solving is manifested in the considerations of graduate TAs choices of example solutions. Twenty-four first-year graduate TAs were asked to discuss their goals for presenting example solutions to students. They were also provided with different example solutions and asked to discuss their preferences for prominent solution features. TAs' awareness, preferences and actual practices related to solution features were examined in light of recommendations from the literature for the modeling of expert-like problem solving approaches. The study concludes that the goal of helping students develop an expert-like problem solving approach underlies many TAs' considerations for the use of example solutions. TAs, however, do not notice and do not use many features described in the research literature as supportive of this goal. A possible explanation for this gap between their belief and practices is that these features conflict with another powerful set of values concerned with keeping students engaged, setting adequate standards, as well as pragmatic considerations such as time requirements and the assignment of grades.

physics.ed-ph↗

arXiv2016

Instructional Goals and Grading Practices of Graduate Students after One Semester of Teaching Experience

Teaching assistants (TAs) are often responsible for grading student solutions. Since grading communicates instructors' expectations, TAs' grading decisions play a crucial role in forming students' approaches to problem solving (PS) in physics. We investigated the change in grading practices and considerations of 18 first-year graduate students participating in a TA professional development (PD) course. The TAs were asked to state their beliefs about the purpose of grading, to grade a set of specially designed student solutions, and to explain their grading decisions. We found that after one semester of teaching experience and participation in PD, TAs did not significantly change their goals for grading (i.e., a learning opportunity for both the student and the instructor) or their grading practice. In addition, TAs' grading practice frequently did not align with their goals. However, some TAs' perceptions of the level of explication required in a student solution did change. Our findings suggest that in order for PD to help TAs better coordinate their goals with appropriate grading practices, PD should focus on TAs' perception of sufficient reasoning in student solutions.

physics.ed-ph↗

arXiv2014

Educational trajectories of graduate students in physics education research

Physics education research (PER) is a rapidly growing area of PhD specialization. In this article we examine the trajectories that led respondents into a PER graduate program as well as their expected future trajectories. Data were collected in the form of an online survey sent to graduate students in PER. Our findings show a lack of visibility of PER as a field of study, a dominance of work at the undergraduate level, and a mismatch of future desires and expectations. We suggest that greater exposure is needed so PER is known as a field of inquiry for graduates, that more emphasis should be placed on research beyond the undergraduate level, and that there needs to be stronger communication to graduate students about potential careers.

physics.ed-ph↗

arXiv2007

TEDI: the TripleSpec Exoplanet Discovery Instrument

The TEDI (TripleSpec - Exoplanet Discovery Instrument) will be the first instrument fielded specifically for finding low-mass stellar companions. The instrument is a near infra-red interferometric spectrometer used as a radial velocimeter. TEDI joins Externally Dispersed Interferometery (EDI) with an efficient, medium-resolution, near IR (0.9 - 2.4 micron) echelle spectrometer, TripleSpec, at the Palomar 200" telescope. We describe the instrument and its radial velocimetry demonstration program to observe cool stars.

astro-ph↗

arXiv2006

Promoting Instructional Change via Co-Teaching

Physics Education Research (PER) has made significant progress in developing knowledge about teaching and learning as well as effective instructional strategies based on this knowledge. Disseminating knowledge and strategies to other faculty, however, has proven difficult. Coteaching is a promising and cost-effective alternative to traditional professional development that may be applicable in many situations. In this article, we discuss the theoretical background of co-teaching and describe our initial experience with co-teaching. A new instructor (MF) cotaught with an instructor experienced in PER-based reforms (CH). The pair worked within the scaffolding of the course structure typically used by the experienced instructor and met regularly to discuss instructional decisions. An outsider (AB) conducted separate interviews with each instructor at the beginning, middle, and end of the semester and observed several class sessions. Classroom observations show an immediate use of PER-based instructional practices by the new instructor. Interviews show a significant shift in the new instructor's beliefs about teaching and intentions towards future use of the PER-based instructional approaches.

physics.ed-ph↗

arXiv2006

Physics Faculty and Educational Researchers: Divergent Expectations as Barriers to the Diffusion of Innovations

Physics Education Research (PER) practitioners have engaged in substantial curriculum development and dissemination work in recent years. Yet, it appears that this work has had minimal influence on the fundamental teaching practices of typical physics faculty. To better understand this situation interviews were conducted with 5 likely users of physics education research. All reported making changes in their instructional practices and all were influenced, to some extent, by educational research. Yet, none made full use of educational research and most had complaints about their interactions with educational researchers. In this paper we examine how these instructors used educational research in making instructional decisions and identify divergent expectations about how researchers and faculty can work together to improve student learning. Although different instructors emphasized different aspects of this discrepancy between expectations, we believe that they are all related to a single underlying issue: the typical dissemination model is to disseminate curricular innovations and have faculty adopt them with minimal changes while faculty expect researchers to work with them to incorporate research-based knowledge and materials into their unique instructional situations. Implications and recommendations are discussed.

physics.ed-ph↗