8,799 research outputs found
Miniaturized Circular-Waveguide Probe Antennas Using Metamaterial Liners
This work presents the radiation performance of open-ended circular-waveguide
probe antennas that have been miniaturized by the introduction of thin
metamaterial liners. The liners introduce an HE mode well below the
natural cutoff frequency, which provides substantial gain improvements over a
similarly sized waveguide probe. A new feeding arrangement employing a
shielded-loop source embedded inside the miniaturized waveguide is developed to
efficiently excite the HE mode and avoid the excitation of other modes
across the frequency reduced band while maintaining the antenna's compactness.
A metamaterial-lined circular-waveguide probe antenna operating over 42% below
its natural cutoff frequency is designed to provide a radiation efficiency of
up to 28.8%. A simple, printed-circuit implementation of the metamaterial liner
based on inductively loaded wires is proposed and its dispersion features are
discussed.Comment: The manuscript has been revised for publication as a 6 page
communication in the IEEE Transactions on Antennas and Propagation. This
included a reduction of material in the theory section, removal of all
discussion on anisotropic theory, and introduction of a novel excitation
sourc
Assessing the Effectiveness of a Computer Simulation in Introductory Undergraduate Environments
We present studies documenting the effectiveness of using a computer simulation, specifically the Circuit Construction Kit (CCK) developed as part of the Physics Education Technology Project (PhET) [1, 2], in two environments: an interactive college lecture and an inquiry-based laboratory. In the first study conducted in lecture, we compared students viewing CCK to viewing a traditional demonstration during Peer Instruction [3]. Students viewing CCK had a 47% larger relative gain (11% absolute gain) on measures of conceptual understanding compared to traditional demonstrations. These results led us to study the impact of the simulation's explicit representation for visualizing current flow in a laboratory environment, where we removed this feature for a subset of students. Students using CCK with or without the explicit visualization of current performed similarly to each other on common exam questions. Although the majority of students in both groups favored the use of CCK over real circuit equipment, the students who used CCK without the explicit current model favored the simulation more than the other grou
Correlating Student Beliefs With Student Learning Using The Colorado Learning Attitudes about Science Survey
A number of instruments have been designed to probe the variety of attitudes, beliefs, expectations, and epistemological frames taught in our introductory physics courses. Using a newly developed instrument -- the Colorado Learning Attitudes about Science Survey (CLASS)[1] -- we examine the relationship between students' beliefs about physics and other educational outcomes, such as conceptual learning and student retention. We report results from surveys of over 750 students in a variety of courses, including several courses modified to promote favorable beliefs about physics. We find positive correlations between particular student beliefs and conceptual learning gains, and between student retention and favorable beliefs in select categories. We also note the influence of teaching practices on student beliefs
Are all things created equal? The incidental in archaeology
Archaeologists evince a strong tendency to impute significance to the material traces they study, a propensity that has been especially marked since the post-processual emphasis on meaning and that has taken on renewed vigour with the turn to materiality. But are there not situations in which things are rather incidental or insignificant? This set of essays emerged from a workshop held in Berlin in April 2018, in which a group of scholars was invited to discuss the place of the incidental in social life in general and in archaeology in particular. Rather than lengthy formal papers, we offer an introduction that presents a general set of reflections on the issue of the incidentalness of things, followed by essays that pursue particular directions raised by that introduction as well as our discussions in Berlin. It is our hope that these brief forays into a complex topic will stimulate further work on this subject
International Symposium White Paper: Principal Workālife Balance and Well-being Matters
In November 2016, delegates from over 32 school leader associations (SLAs) from across the globe participated in the third Annual International Symposium on the Role of Professional Associations for School Leaders held in Toronto, Ontario. The symposium explored research on work intensification, generational theory and its influence on principal work and aspirations, and work-life balance and well- being. This White Paper draws on the work of the symposium and the wider evidence base to argue that we currently face a crisis in principal well-being on a global scale that, without urgent policy and practice intervention, will impact school- and system-level outcomes for generations. We argue for the importance of national and local recognition and understanding of the current status of principal well-being and work-life balance, highlight the factors and conditions that impact the work of principals with implications for well- being and work-life balance in the role, and proffer strategies and interventions that SLAs can undertake to enhance and promote principal well-being....a crisis in principal well-being on a global scale. School leaders have an influential and essential role in securing student academic and personal success, creating the conditions required for school improvement by acting as ālead learnersā, focusing intently on the quality of teaching and learning. Yet there is growing evidence of a global transformation in the roles and nature of principal work (UNESCO 2009; OECD 2003, 2008) shaped by global patterns of educational reform over the last decade (Fullan 2008; Evans 2016; Edge 2016), the rapidity of innovation in information and communication technology (ICT) and its integration into the work and personal lives of educators and students (Dibbon & Pollock 2007; Gurr 2004, 2000: Pollock & Hauseman 2017; Pollock 2015; Carroll 2010), and the growing diversity (and growing awareness of diversity) of student populations and student needs (Ryan 2006; Briscoe & Pollock 2017; ATA 2014; Pollock, Wang & Hauseman 2015). The resulting escalation in workload brought about by these shifts has been described as āprincipal work intensificationā ā a phenomenon defined by an increasing volume and complexity of school leadersā work, roles and responsibilities (Pollock 2014, 2015, 2016; Pollock, Wang & Hauseman 2015). Principals in several jurisdictions are reporting term-time work hours between 50 and 65 hours a week (Riley 2013, 2014, 2015; Bristow, Ireson & Coleman 2007; Alberta Teachersā Association 2014). In a 2012 MetLife Foundation principal survey ā75 percent of the respondents said that the job had become too complex,ā creating undue stress (Pollock et al 2012, p. 3). Work intensification hinders the development and sustainable healthy work-life balance, with significant implications for principal well-being (La Placa et al 2013) and subsequently the well-being of schools and school systems. ...intended and unintended consequences. Globalization, demographic changes, growing global awareness of social equity and human rights issues, and rapid technological innovation create a demand and pressure on public education systems to respond and adapt. Over the last decade, educational change in many jurisdictions has been characterized by a rapid flow of initiatives designed to improve student outcomes. These shifts are occurring against a backdrop of structural and funding pressures that demand increased flexibility and creativity from school leaders, without a concomitant increase in, and at times a reduction of committed resources (Auerbach 2012; Barr & Saltamrsh 2014; Ontario Ministry of Education 2010; People for Education 2012; Sanders 2014; Wallace Foundation 2013). The constant pressure to adopt new programs, a lack of alignment between reforms, and competing accountability systems for different initiatives all contribute to work intensification and negative well-being outcomes for school leaders. Under these conditions, the increasing challenges to principal work-life balance and well-being are creating multifaceted implications for schools and school systems. The principalship is an increasingly undesirable position for prospective and current administrators, creating issues of both recruitment and retention across systems (Leithwood & Azah 2014a, b). Simultaneously, current school leaders find themselves pulled away from instructional leadership, with time increasingly co-opted by operational, accountability and administrative demands created by misaligned system-level priorities (SPEF 2015; The Human Cost 2014; Riley 2014). ...support and advocacy, practice and decision-making. SLAs play an important role in addressing these pressures, acting as knowledge brokers, advocates and policy activists for the well-being of their constituents. Globally, SLAs are developing strategies to support their membersā well-being and advocate for better approaches to work-life balance. Building on the current best practices and experience of symposium participants, this White Paper makes several recommendations for areas of advocacy and operational support that address the unintended consequences arising from the pace and scale of education reform, the growing centrality of ICT, and the changing nature of the principalsā role. These recommendations fall into four key categories: ā¢ Jurisdictional policy advocacy ā¢ Redefining the principals role ā¢ Advocacy for school- and system-level support and ā¢ Delivery of support and development opportunities. The applicability of specific recommendations depends on local and national context, SLA jurisdiction, mandate and membership structure. Importantly, while SLAs can act as advocates for policy change, work to share resources, and offer continued professional learning, coaching and mentoring for their members, the challenge of addressing principal well-being and work-life balance extends beyond principals and their professional associations: it rests in the hands of policy makers and school systems
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