Abstract
Music education majors report low exposure to creative musical activities (CMAs) despite increased discourse surrounding the inclusion of CMAs in standards, curricula, publications, and practice. The purpose of this study was to compare preservice music teachers’ (PMT) and music teacher educators’ (MTE) experiences with CMAs. We used an anonymous survey instrument to explore definitions, perceived importance and preparedness, and the incorporation of CMAs within undergraduate music education curricula. MTEs and PMTs valued the inclusion of CMAs in preK–12 curricula, PMTs felt most prepared to teach arranging and least prepared to teach composing with their future preK–12 students, and PMTs valued and desired more opportunities to practice CMAs in undergraduate curricula. MTEs should consider integrating these activities as regular components in undergraduate music curricula.
Keywords
The U.S. Department of Education et al. (2002) reported 34% of elementary music specialists gave moderate or major emphasis to improvising, and only 25% gave moderate or major emphasis to composing and arranging during the 1999-2000 school year (p. 82). Since then, policymakers have worked to revise national and state standards so that creative musical activities (CMAs)—arranging, composing, and improvising—are afforded greater status and all students are encouraged to “conceive and develop new artistic ideas and work” (National Coalition for Core Arts Standards, 2016, p. 13). While inservice music teachers generally perceive CMAs to be an important part of the curriculum (Fairfield, 2010; Koops, 2009; Snell, 2012), few regularly include CMAs in their instruction (Schopp, 2006; Strand, 2006), “citing lack of time, resources, and physical teaching space as significant challenges” (Fairfield, 2010, pp. v–vi).
A Historical Perspective
Allowing more opportunity for the individual to create and invent would bring theory and practice closer together, and would win over . . . many children and adolescents who are repelled by the monotony of run-of-the-mill technical and theoretical instruction. (Ferand, 1940, p. 125)
Creativity has remained a central focus of music education discourse throughout the 20th century. In the 1950s and 1960s, the Ford Foundation sponsored two major endeavors to promote creativity through music education. The first, the Young Composers Project, placed young composers in residencies at public schools (Mark et al., 1999); the second, known as the Contemporary Music Project for Creativity in Music Education, was a grant given to MENC (now the National Association for Music Education) designed to increase emphasis on the creative aspect of music in public schools (“Contemporary Music Project,” 1973). The Bennington Institute ventured to increase music teachers’ musicianship through composition in 1962 (Moon, 2006). In 1970, members of the Manhattanville Music Curriculum Project aspired to revitalize music education through professional development and by infusing student-centered creative activities into a spiral curriculum (Thomas, 1970). Authors of the Comprehensive Musicianship through Performance Project advanced a model for students to address the gap between technical ability and musical understanding by embedding CMAs in ensemble rehearsals (Wisconsin Music Educators Association, 2019). The following decade, attendees of the Ann Arbor Symposium explored the role of motivation and creativity in music education (Cox, 1983), and in 1994 the Consortium of National Arts published the National Standards for Music Education with improvising and composing/arranging listed as critical components of a well-rounded music education.
Following the creation of the national standards, many states published their own arts standards. In 2014, the National Core Arts Standards reimagined the 1994 national standards to focus on developing artistic literacy, which required students to “engage in artistic creation processes directly” (National Coalition for Core Arts Standards, 2016, p. 17). According to the four artistic processes of the National Core Arts Standards, students should: create; perform, present, and produce; respond; and connect. Around the same time as the revision of the national standards, Patricia Shehan Campbell, President of the College Music Society, appointed a national task force to consider what it means to be an educated musician in the 21st century and to make recommendations for progressive change in the undergraduate music major curriculum. The task force noted rapid progress in creative and expressive dimensions of music over the past several decades and recommended “three key pillars necessary to ensure the relevance and rigor of the undergraduate music curriculum” (Campbell et al., 2016, p. iii), including creativity, diversity, and integration.
Research on Music Creativity in Education
Researchers have defined creativity as a process of thinking (Hickey & Webster, 2001; Snell, 2012), an original product (Csikszentmihalyi, 2014; Fairfield, 2010; Hickey, 2001), or the generation of unique ideas (Azzara, 2002; Biasutti, 2015). According to Running (2008), the majority of CMAs “are in the areas of improvisation and composition” (p. 43). Ideas for including arranging in music classes, often coupled with composing (Brame, 2005; Bush, 2007; Randles, 2009), rarely stand alone as a focus of scholarship. Music researchers have directed more attention to composition and improvisation, enough to warrant extensive literature reviews on composition (Henry, 1996; Viig, 2015) and improvisation (Azzara, 2002; Azzara & Snell, 2016; Grasso et al., 2019). Recent handbooks contain numerous curricular suggestions for the inclusion of composition (Kaschub & Smith, 2013; Kerchner & Strand, 2016; Randles & Stringham, 2013) and improvisation (Burton & Snell, 2018; Holt & Jordan, 2008; Stringham & Bernhard, 2019) in the classroom.
Obstacles and Barriers
Despite myriad resources available to music educators, many individuals report numerous obstacles that prevent them from including CMAs in the classroom to a greater extent. In a survey of 339 Indiana music teachers, Strand (2006) found that other learning activities, lack of access to technology, and lack of time were reasons for not including composition. Fairfield (2010) found similar results in a national survey of 283 elementary general music teachers, who indicated obstacles included lack of time, technology, and physical space resources. Lack of exposure and preparation at the undergraduate level may have also played an important role in determining whether teachers chose to include arranging, composing, and improvising in the curriculum (Menard, 2015). Snell (2012) surveyed 314 New York State music teachers, who reported feeling least prepared to address arranging, composing, and improvising when compared with other 1994 National Standards. Bernhard (2013) highlighted how instruction in improvisation is commonly relegated to the study of jazz, and posited preservice music teachers (PMTs) who do not play a typical jazz instrument may not have opportunities to improvise in their undergraduate experiences. These findings may help explain the lack of comfort expressed by preservice and inservice music teachers with regard to teaching improvising.
Perceptions of Preparation
In 2002, Brophy surveyed 237 music teachers representing 43 states, and revealed that only 1 out of 10 felt prepared to teach improvisation and composition as a result of their collegiate training. Similarly, Stringham et al. (2015) reported—in a national survey of 321 instrumental methods instructors—general support for improvisation and composition but low levels of prioritization in instrumental methods courses. Participants in a study specific to improvisation by Forsythe et al. (2007) rated improvisation the least learnable musical activity in music teacher training institutions. To address these deficiencies, Bernhard and Stringham (2016) encouraged more opportunities for “preservice candidates to experience and teach improvisation” (p. 388).
Need for Study
Because many researchers have primarily focused on composing or improvising, we identified the need for a study that also explores the process of arranging. With nearly 80 years of advocacy for creativity and for the inclusion of CMAs in schools, we wanted to know what prevents teachers from answering these calls for change. In what courses and in which spaces are undergraduates learning and engaging with CMAs? How prepared do they feel to include these activities in their future music classrooms? Is there an increased focus on CMAs in music teacher education programs, and if so, where is the disconnect between CMA representation within undergraduate coursework and the implementation of CMAs in preK–12 music curriculum and instruction? Answering these questions may help bridge the gap between practice and research and provide teachers with the confidence needed to incorporate more creative activities in the curriculum. Through a nationwide survey of PMTs and music teacher educators (MTEs), we obtained current information about their CMAs—their experiences, perceptions, and practices specific to arranging, composing, and improvising—and aimed to better understand why the potential benefits of engaging music teachers and students in CMAs may remain unrealized.
Purpose
We designed the present study to compare PMTs’ and MTEs’ self-reported experiences with CMAs, and the incorporation of CMAs as part of music teacher education curricula. Five research questions guided this inquiry:
Method
Research Design
This quantitative study for PMTs and MTEs from across the nation is an adaptation of a survey of New York State school music teachers (Piazza, 2018). Lines of inquiry from existing surveys (Fairfield, 2010; Menard, 2015; Schopp, 2006; Snell, 2012; Strand, 2006) guided the development of the questions. We piloted these prompts with undergraduate music education students at a liberal arts college in Pennsylvania; these students were excluded from participating in the present survey.
Sampling and Data Collection
We identified 537 out of 643 total accredited institutions on the National Association of Schools of Music website that offered undergraduate degrees in music education, and procured e-mail addresses for coordinators or department chairs at each institution. We also invited faculty known to us or from non-accredited institutions to participate in our study, and encouraged them to forward the survey link to (a) anyone involved in teaching undergraduate music education courses and (b) undergraduate students in the music education program at their institution. We also identified eight Facebook groups known for their focus in music teacher education, creativity, and research, then posted a link to the survey in each group. This sampling method resulted in a total of 331 survey responses from 34 states, including 236 PMTs and 95 MTEs. Of the 331 total participants, 292 responded to the e-mail invitations and 39 responded to the social media posts. We kept the survey active for 4 months.
Survey Instrument
We designed an anonymous, split-form questionnaire (see online supplemental file) with multiple sections that used survey logic to allow for the concurrent administration to both PMTs enrolled as undergraduate music education majors and MTEs. We asked all participants to select, from a list of six choices, the best definition of CMAs. We included definitions of creativity found both within and outside of the music education field (see Table 1 in the online supplemental file). We also asked all participants to rank the importance of including arranging, composing, and improvising in undergraduate and preK–12 music curricula. We used the following definitions: arranging—the manipulation of preexisting musical ideas to create an original work; composing—the creation and preservation (with or without notation) of original ideas; improvising—the spontaneous creation of original musical ideas (without revision).
Undergraduate student participants responded to 5-point Likert-type scales to report their comfort with, preparedness for, and likelihood of emphasizing CMAs in their future work with preK–12 students. Using the same scale type, MTEs indicated how comfortable and prepared their undergraduate students were to include CMAs with future preK–12 students. We explored the incorporation of arranging, composing, and improvising within undergraduate curricula. We asked PMTs to identify the classes (i.e., theory, history/musicology, applied lessons, performance ensembles, general music methods, instrumental/choral methods, voice technique, piano technique, instrumental technique, and student teaching) in which they were required to arrange, compose, or improvise. Using a free-response option, we also prompted undergraduates to describe a project they did, or a class in which they felt they could be particularly creative.
Data Analysis Procedures
Quantitative survey data were imported to SPSS and we collaborated on this analysis phase. All open-ended responses were compiled into Google Sheets, and we independently coded those responses using in vivo and concept codes (Saldaña, 2016). We then discussed themes that emerged from the coding process and formed consensus on thematic codes. As this was an anonymous survey, we could not contact participants for member checking. As a preliminary analysis procedure, and to check for potential sampling bias, we ran a series of chi-square independence tests for recruitment modality (e-mail or Facebook group) crossed with major survey variables (e.g., CMA definitions; comfort, importance, and preparedness perceptions; course requirements). There were no significant associations between recruitment modality and participant responses.
Results
Definitions of Creative Musical Activities
The three most commonly selected definitions of CMAs were (a) taking musical risks (Hickey & Webster, 2001); (b) a blend of generating and composing (Snell, 2012); and (c) producing a product that is new for the creator (Webster, 2013). Of the six provided definitions of creativity, these three accounted for 81.3% of total responses (n = 269). There was a significant difference in distribution of definitions for CMAs based on the type of respondent (MTE or PMT), χ2(5, n = 331) = 14.901, p < .05; MTEs were significantly more likely to define CMAs as “generating a musical product that is novel or unique” than were PMTs.
Types of Creative Musical Activities in Undergraduate Curricula
PMTs indicated whether arranging, composing, and improvising were included in their undergraduate classes. Due to the different numbers of students who had taken each course, statistics are reported as percentages of students who answered “Yes” or “No”; students who selected “Have not taken course” are not included in the reported percentages. PMTs most frequently identified theory as the course in which arranging (n = 163, 69.4%) and composing (n = 214, 91.1%) were included, and applied lessons as the course in which improvising (n = 127, 55.0%) was included. Following this primary analysis, we calculated new composite variables representing the percentage of students who indicated they experienced all three CMAs for each of the given courses. PMTs most frequently identified theory (n = 69, 29.4%), general music methods (n = 44, 26.5%) and instrumental/choral methods (n = 35, 20.3%) as the courses in which arranging, composing, and improvising were included as a part of the curriculum. We created three new composite variables representing the percentage of courses in which each student experienced (a) arranging, (b) composing, and (c) improvising. Pearson correlations, with pairwise deletion, showed moderate, significant relationships between all three CMAs as experienced by each PMT. PMTs who experienced arranging in a greater percentage of their undergraduate classes were more likely to also experience composing (r = .59, p < .01) and improvising (r = .52, p < .01) in a greater percentage of their undergraduate curricula. PMTs who composed in a greater percentage of their undergraduate courses were more likely to also improvise (r = .52, p < .01) in a greater percentage of courses.
Incorporation of Creative Musical Activities in Undergraduate Curricula
We prompted PMT participants to describe a project they did, or a class in which they felt they could be particularly creative. We also asked them if they had experienced a particular emphasis (or lack thereof) on arranging, composing, or improvising activities as an undergraduate student. Of the 236 PMTs who responded to the survey, 167 (70.8%) volunteered a free response. After coding open-ended responses of the PMTs, we identified three themes: (a) PMTs value CMAs and often seek opportunities to arrange, compose, or improvise outside the curriculum; (b) PMTs desire more opportunities to arrange, compose, and improvise; and (c) when CMAs are incorporated, they are often centered on project-based learning connected to a Western historical period and practice.
Student-Initiated Opportunities
Students reported initiating opportunities to experience CMAs at their undergraduate institutions. They indicated that without actively seeking out opportunities on their own, they would not have been exposed to arranging, composing, and improvising as an embedded part of the curriculum. One student reported “I am enrolled in an arranging class. I also have taken a few semesters of improv. I went out of my way for both of these experiences.” Another wrote “As someone who loves to compose and improvise . . . I have to look to my own free time to pursue those creative musical aspects.” Unexpectedly, we discovered that the importance of CMAs prior to undergraduate study was a reportedly powerful experience. Though we prompted PMTs to respond based on undergraduate classes, many referenced high school experiences. One representative quote stands out: “Most of the time that I was able to be creative was back in high school with jazz band.”
Desire for More Opportunities
Many students were infrequently asked to arrange, compose, or perform in their undergraduate courses: “There were some opportunities where I had the chance to do so, but these opportunities were scarce.” Many students indicated they desired more frequency in the inclusion of CMAs in their undergraduate curriculum. One student responded “We have one class based on arranging, but it doesn’t help me or my peers be creative. I’ve done no composing in college so far and little improvising.” Another student desired more opportunities, simultaneously expressing the perceived importance of improvising: “I definitely won’t have enough skill leaving these classes to teach my students how to improvise, which I think is the most important part of being a musician.” One student indicated an embedded approach to CMAs in their curriculum: “All types of creative music experiences have been woven throughout other coursework (other than a required arranging course), with a heavy focus on composition.”
Project-Based Creative Musical Activities
Students who shared specific activities often referenced projects that focused on Western historical period music. From students’ perspectives, learning served to advance a particular way of knowing music, rather than as an outlet for creative expression. Students reported assignments that required them to compose “a piece that would sound similar to Erlkönig,” “a sentence and a period that would later be used to create a motet and a sonata,” or “an isorhythmic motet, as well as a Romantic-style lied.” One student described a project for which they had to “arrange madrigals in Music History.” One student felt the most musically creative project was in “orchestration class where [they] arranged Debussy, Bach, Bolero, Mozart, and the Final Countdown for various ensembles.”
Perception of Preparedness
We asked PMTs to identify how important it was to include CMAs in their future work with preK–12 students, and how prepared they felt to do so. Similarly, MTEs reported their perceptions of importance and how prepared they believed their PMTs were to incorporate CMAs when teaching music. Nearly all respondents felt it was either “Important” or “Very Important” to foster the development of creative musicians (PMT: n = 226, 95.8%; MTE: n = 90, 94.7%). Arranging, composing, and improvising activities were considered “Important” or “Very Important” by a larger proportion of MTEs than PMTs (arranging PMT: n = 141, 59.7%, MTE: n = 72, 75.8%; composing PMT: n = 169, 71.7%, MTE: n = 78, 82.1%; improvising PMT: n = 207, 87.7%, MTE: n = 86, 90.5%). PMTs felt slightly less prepared to teach composing (M = 2.28, SD = 1.11) than either arranging (M = 2.33, SD = 1.13) or improvising (M = 2.32, SD = 1.20). MTEs’ perceptions of their students’ levels of preparation were similar (composing, M = 2.24, SD = 0.94; arranging, M = 2.42, SD = 0.92; and improvising, M = 2.34, SD = 0.96).
We offered MTEs the option to provide additional information regarding the inclusion of CMAs at the end of the survey; of the 95 MTEs who completed the survey, 25 (26.3%) responded. In open-responses, MTEs consistently validated the importance of incorporating CMAs within undergraduate curricula. One remarked, “it is IMPERATIVE that CREATING be at the forefront of music education.” Another MTE wrote, I emphatically believe that the inclusion of these activities and a strong level of comfort in these skills, coupled with an equally strong philosophy of Music Education that drives future teachers to ensure these activities are regularly made available to music students, are all critical to the future success and health of our profession.
MTEs indicated CMAs are involved in many classes, but “are a drop in the bucket on the other performative-based courses and ensembles that take up student attention.”
Discussion
There is a far greater joy in enabling a child to create something than in creating it one’s self, for then one has the gratification of feeling a constructive power in the mental development of human beings rather than power over mere materials. (Coleman, 1922, p. 208)
For decades, music educators have been advocating for revisions to music curricula that engage students more with the creative processes of music. Most MTEs claim to value CMAs (Forsythe et al., 2007; Stringham et al., 2015), but few fully embed these activities throughout undergraduate music education curricula (Bernhard & Stringham, 2016). Beyond the music education curriculum, music school faculty commonly focus on the development of technical musicianship skills that center around analyzing and recreating “masterworks” of Western European and American composers (Campbell et al., 2016). This focus not only overlooks the diversity of identities, cultures, abilities, interests, and ways of musicking in our communities, but diminishes opportunities for creativity and the development of skills necessary for becoming fully facile musicians—ones who can fluidly analyze, interpret, perform, and create music.
Curricular Inclusion
Based on data from this study, we identified curricular spaces that support and embed CMAs within music teacher education. However, we also believe there is a need for more openings for creativity, diversity, and integration in music curricula (Campbell et al., 2016), echoing calls from other researchers who suggest there is still more work to be done (Bernhard & Stringham, 2016; Brophy, 2002; Stringham et al., 2015). When PMTs experience arranging, composing, or improvising, it is typically within music theory or music education methods courses, applied lessons, and ensembles. Interestingly, composing and arranging are experienced by PMTs in similar classes (e.g., theory, general music methods, instrumental/choral methods, and student teaching), whereas improvising is often experienced as a separate facet of their music education (e.g., applied lessons and performance ensembles).
Within individual courses, PMTs typically experience CMAs through projects centered on music from Western historical periods (e.g., motets, sonatas, madrigals, and lieder), rather than through diverse musical styles, forms, and genres. In many programs across the country, music faculty ask PMTs to compose and arrange in specific styles in their theory and orchestration courses—styles that emulate techniques, as one participant described, used by Western composers such as “Debussy, Bach, or Mozart.” Though most PMTs reported that CMAs are relegated to specific courses, a more integrated approach to music curriculum exists—one where creative activities are, as one participant wrote, “woven throughout coursework.” Such integrated approaches are not limited by size nor type of institution and exist in private and public institutions, as well as those ranging from very small to very large.
Implications for Music Teacher Education
We learned both PMTs and MTEs value arranging, composing, and improvising, echoing and extending findings from Stringham et al. (2015). Similar to studies of inservice teachers (Piazza, 2018; Fairfield, 2010), we discovered a perceived lack of time remains a real concern among PMTs and MTEs. Relegating aspects of music creativity to individual courses puts the burden of responsibility on one MTE. Consistent integration of CMAs may (a) increase confidence among PMTs and MTEs to generate new musical products, (b) provide additional opportunities for culturally responsive and inclusive teaching practices, and (c) allow MTEs to share accountability for integrating CMAs across the curriculum.
As one MTE indicated, “Creative musical work is extremely important for those entering the teaching profession.” Not surprisingly, PMTs desire more opportunities to arrange, compose, and improvise both inside and outside the undergraduate music education curriculum. When CMAs were rarely included in (or omitted from) curricula, determined PMTs often looked for opportunities to arrange, compose, and improvise. Accordingly, MTEs can promote learner agency by challenging PMTs to seek out opportunities to arrange, compose, and improvise.
MTEs and PMTs were uncertain whether undergraduate institutions adequately prepared music education majors to incorporate CMAs in their future teaching. Rather than relying on varied or uncoordinated experiences to provide PMTs with the skills needed to arrange, compose, and improvise, MTEs might consider embedding more opportunities for CMAs throughout the curriculum or even requiring that PMTs complete one or more dedicated courses in creative musicianship. MTEs might also discuss with PMTs opportunities for creative experiences, and together uncover ways to fully embed these ideas through their curriculum.
Re-envisioning the Culture of Creative Musical Activities
Music educators need to re-envision the culture of CMAs. This may require a level of vulnerability and recognition of insecurities among practicing teachers at all levels. Farrell (2018) highlights “the importance of teachers being vulnerable in front of their students” (p. 168). MTEs who feel uncomfortable with CMAs might model vulnerability by arranging, composing, and improvising together with PMTs. In this way, PMTs who feel insecure with their own creative abilities may feel more comfortable modeling this approach with their future students. MTEs should consider requiring PMTs to include CMAs in existing assignments and lesson plans (e.g., arranging a simple folk melody by changing the mode, meter, or texture). Additionally, we urge MTEs to interrogate their own curricula for opportunities to embed more CMAs, and to teach PMTs how to teach their students to arrange, compose, and improvise.
When MTEs advance historical practices, they perpetuate a cycle of canon and epistemologies that extend our historical legacies and the dominant collective identity, elevating certain practices while excluding others. Questions of “Who can be a teacher?” may be addressed by creating classroom sites and situations that allow and embrace the creation of new ideas. When teachers and students learn beside one another and create music together, they are “shaped by histories that are contingent rather than inevitable” (Talbot, 2013), honoring the diversity each student brings to the classroom.
Regarding one MTE’s comment about becoming “victims of institutional inertia,” teachers may be more free than they realize to resist the homogenization of practice commonly found among institutions. By including more CMAs, in both vulnerable and co-constructive ways, students and teachers become free to explore new ways of knowing and making music together. As another MTE suggested, providing PMTs with more contemporary experiences may better represent “the context of small, democratic ensembles (jazz combos, rock bands) rather than the traditional large ensembles of the ‘composer/arranger’ of historic lore.”
Suggestions for Future Research
It is important to articulate the limitations we encountered in designing, distributing, and collecting our data. This survey was likely distributed by MTEs who were interested in creativity research. Therefore, results may unequally represent programs that prioritize CMAs, and may not be generalized to the national population of MTEs and PMTs. Responses may also reflect pockets of the population in which the researchers had close associations.
This study adds to the mounting body of research in which scholars call for a pedagogical shift toward increased CMAs in music education curricula. Researchers could use longitudinal studies to examine how PMTs feelings of preparedness might change when they become inservice teachers. Researchers might adapt study designs from other disciplines to better understand what motivates music teachers to change their practices.
Questions still remain that warrant further exploration. With nearly 80 years of worth of scholarship and symposia promoting the inclusion of CMAs in schools, what is still preventing teachers from answering these calls for change? What motivates certain music teachers to include CMAs in light of perceived challenges? How can MTEs learn from and/or assist teachers who regularly include CMAs?
Conclusion
Listening to the voices of the PMTs and MTEs may provide openings for more creative, relevant, and responsive teaching. We believe teaching practices primarily focused on responding to, analyzing, or recreating performance pieces limit the potential for students to become musically fluent beings. Instead, we advocate for teaching practices that embed a variety of CMAs across music curricula. MTEs and music teachers must critically reflect on their own practices, celebrate and advance existing models that foster creative musical environments, and actively seek to address the needs of all students. When MTEs respond to and support undergraduate students’ voices and their musical development, PMTs may become the kind of preK–12 music teachers who offer students opportunities to both create and recreate musical ideas. In turn, those students gain the freedom to respond to and express their lived experiences through arranging, composing, and improvising.
Supplemental Material
JMTE_Table_1 – Supplemental material for Creative Musical Activities in Undergraduate Music Education Curricula
Supplemental material, JMTE_Table_1 for Creative Musical Activities in Undergraduate Music Education Curricula by Erik S. Piazza and Brent C. Talbot in Journal of Music Teacher Education
Supplemental Material
Survey_Instrument_with_consent – Supplemental material for Creative Musical Activities in Undergraduate Music Education Curricula
Supplemental material, Survey_Instrument_with_consent for Creative Musical Activities in Undergraduate Music Education Curricula by Erik S. Piazza and Brent C. Talbot in Journal of Music Teacher Education
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Supplemental Material
Supplemental material for this article is available online.
References
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