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A simple method for reducing the linewidth of a diode laser while maintaining high output power is described. It is based on a dispersive prism and a thin etalon for retroreflective feedback. The etalon creates two weak external cavities that provide spectral selectivity that is periodic with a period equal to the etalon’s free spectral range. The method was applied to a multimode blue laser diode, which in the absence of feedback features a linewidth of several nanometers. The spectral properties of the laser were investigated for different etalon thicknesses and operating currents and tested in the presence of temperature fluctuations. With a SF11 equilateral uncoated prism near Brewster’s angle and a 0.3 mm-thick uncoated fused silica etalon, the linewidth was reduced 20-fold to 70 pm (3.6 cm−1) with an output power of 3 W at a current of 2.15 A. The largest diode current probed was 2.75 A, which resulted in a linewidth of 100 pm (5.1 cm−1) and an output power of 4 W. In contrast to the use of, for example, a volume Bragg grating, a high degree of flexibility is afforded as the same prism–etalon pair can be used across the visible and near infrared. 

ABSTRACT Localization of fast radio bursts (FRBs) to arcsecond and subarcsecond precision maximizes their potential as cosmological probes. To that end, FRB detection instruments are deploying triggered complex-voltage capture systems to localize FRBs, identify their host galaxy, and measure a redshift. Here, we report the discovery and localization of two FRBs (20220717A and 20220905A) that were captured by the transient buffer system deployed by the MeerTRAP instrument at the MeerKAT telescope in South Africa. We were able to localize the FRBs to precision of $$\sim$$1 arcsecond that allowed us to unambiguously identify the host galaxy for FRB 20220717A (posterior probability $$\sim$$0.97). FRB 20220905A lies in a crowded region of the sky with a tentative identification of a host galaxy but the faintness and the difficulty in obtaining an optical spectrum preclude a conclusive association. The bursts show low linear polarization fractions (10–17 per cent) that conform to the large diversity in the polarization fraction observed in apparently non-repeating FRBs akin to single pulses from neutron stars. We also show that the host galaxy of FRB 20220717A contributes roughly 15 per cent of the total dispersion measure (DM), indicating that it is located in a plasma-rich part of the host galaxy which can explain the large rotation measure. The scattering in FRB 20220717A can be mostly attributed to the host galaxy and the intervening medium and is consistent with what is seen in the wider FRB population. 

As the world becomes increasingly complex, students will be faced with problems that require outside-of-the-box thinking. The complexity of these problems is compounded when considering the needs of people and their impacts on the environment. The Next Generation Science Standards (NGSS) incorporate engineering design to develop students’ skills at defining and delimiting problems, designing solutions to problems, and optimizing the design solutions—all while maximizing benefit and minimizing risk (NGSS Lead States 2013). Design thinking furthers the engineering design process by acknowledging that solutions to engineering design problems may differ depending on the community the solution serves and the environment for which the solution is designed (Brown 2008). For example, if the challenge is to “build a strong building,” students located in Florida would consider whether the building could handle the strong winds and rains of a hurricane, while students located in California, where earthquakes are common, may view strong buildings as those that can withstand earthquakes. 

Learner-centered interactions, whether in formal or informal settings, are by their nature unscripted and require both the educator and learner to improvise. In fact, improvisation skills have been recognized as beneficial and applied in a variety of professional development training programs (including science communication, organizational development in university administration, teambuilding and leadership in business, and communication skills in medical education); yet, their inclusion in educator training has been limited. MOXI and UCSB partnered with a professional actor and theater instructor (third author of this paper) to implement applied improvisation training to support informal educators' skills development. After four years of incorporating applied improvisation training in our facilitation training program, we have found that the basic skills of listening, observing, and responding that are critical in learner-centered education are taught effectively through the well-developed, practical, and fun exercises of improvisational theater. In this article, we describe our applied improvisation training and how it builds skills pertinent to implementing learner-centered facilitation, how graduates of our training program connected applied improvisation training to their facilitation, and how other institutions can incorporate it into preparing educators for working in either informal or formal settings. 

Communication of ideas involves the simultaneous efforts of verbal, physical and neurological processes (Sherr, 2008). In elementary classrooms where young students are in the process of developing their verbal capacities, gestures from both the teacher and students serve as a key component of communication of new ideas and the processing of social information (Foglia & Wilson, 2013). Thus far, research efforts to understand how students utilize gestures in the communication and understanding of ideas have focused primarily on mathematics and the physical sciences (see Nemirovsky & Ferrara, 2009; Nuñez, Edwards & Matos, 1999; Shapiro, 2014; Sherr, 2008). With the introduction of the Next Generation Science Standards (NGSS Lead States, 2013), students engineering is now included in K-12 instruction. Engineering education centers around designing and optimizing solutions to engineering challenges. The creation of a design solution differentiates engineering education from other classroom subject areas. Current work in engineering education focuses mostly on students’ words or drawings, leaving out gestures as an important component of students' communication of engineering designs. This study aimed to contribute to the general understanding of students’ use of gestures and manipulatives when discussing their engineering design solutions and is part of a larger NSF-funded project. Students participated in pre- and post-field trip classroom activities that extended learning done on an engineering-focused field trip to the local science center into the classroom. For this study, we focused on a module that challenged students to design a craft that either slowed the fall of a penny (classroom engineering design challenge) or hovered in a column of upward moving air (field trip engineering design challenge). We analyzed six videos (3 from the classroom and 3 from the field trip) of first-grade student explanations of their crafts to identify their use of gestures and prototyped craft design solutions in communicating. In this paper, we explore how student use of gestures and use of prototyped design solutions overlap and differentiate to understand how student sense-making can be understood through each. 

We present design principles for leveraging the affordances of schools and an interactive physical science museum to design curriculum modules that result in students learning physics through the practices of science and engineering. The modules include a field trip program and pre and post activities implemented in elementary school classrooms. The design principles are the result of research conducted during the first two years of a three-year design-based implementation research (DBIR) project and conducted through a long term Research-Practice Partnership (RPP) and on iterative development and testing the field trips and activities with 18 classrooms ranging from grades 1 through 6 and representing a range of demographics.