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Abstract We present 0.″4 resolution imaging polarimetry at 8.7, 10.3, and 12.5 μ m, obtained with CanariCam at the Gran Telescopio Canarias, of the central 0.11 pc × 0.28 pc (4.″2 × 10.″8) region of W51 IRS2. The polarization, as high as ∼14%, arises from silicate particles aligned by the interstellar magnetic field ( B -field). We separate, or unfold, the polarization of each sightline into emission and absorption components, from which we infer the morphologies of the corresponding projected B -fields that thread the emitting- and foreground-absorbing regions. We conclude that the projected B -field in the foreground material is part of the larger-scale ambient field. The morphology of the projected B -field in the mid-infrared (mid-IR) emitting region spanning the cometary H ii region W51 IRS2W is similar to that in the absorbing region. Elsewhere, the two B -fields differ significantly with no clear relationship between them. The B -field across the W51 IRS2W cometary core appears to be an integral part of a champagne outflow of gas originating in the core and dominating the energetics there. The bipolar outflow, W51north jet, that appears to originate at or near SMA1/N1 coincides almost exactly with a clearly demarcated north–south swath of lower polarization. While speculative, comparison of mid-IR and submillimeter polarimetry on two different scales may support a picture in which SMA1/N1 plays a major role in the B -field structure across W51 IRS2. 

We present the first mid-IR detection of the linear polarization toward the star CygOB2-12, a luminous blue hypergiant that, withA_V≈ 10 mag of foreground extinction, is a benchmark in the study of the properties of dust in the diffuse interstellar medium. The 8–13μm spectropolarimetry, obtained with the CanariCam multimode camera at the Gran Telescopio CANARIAS shows clear trends with wavelength characteristic of silicate grains aligned in the interstellar magnetic field. The maximum polarization, detected with 7.8σstatistical significance near 10.2μm, is (1.24 ± 0.28)% with position angle 126° ± 8°. We comment on these measurements in the context of recent models for the dust composition in the diffuse interstellar medium.

 

Purpose The purpose of this paper is to explore the designed cultural ecology of a hip-hop and computational science, technology, engineering, and mathematics (STEM) camp and the ways in which that ecology contributed to culturally sustaining learning experiences for middle school youth. In using the principles of hip-hop as a CSP for design, the authors question how and what practices were supported or emerged and how they became resources for youth engagement in the space. Design/methodology/approach The overall methodology was design research. Through interpretive analysis, it uses an example of four Black girls participating in the camp as they build a computer-controlled DJ battle station. Findings Through a close examination of youth interactions in the designed environment – looking at their communication, spatial arrangements, choices and uses of materials and tools during collaborative project work – the authors show how a learning ecology, designed based on hip-hop and computational practices and shaped by the history and practices of the dance center where the program was held, provided access to ideational, relational, spatial and material resources that became relevant to learning through computational making. The authors also show how youth engagement in the hip-hop computational making learning ecology allowed practices to emerge that led to expansive learning experiences that redefine what it means to engage in computing. Research limitations/implications Implications include how such ecologies might arrange relations of ideas, tools, materials, space and people to support learning and positive identity development. Originality/value Supporting culturally sustaining computational STEM pedagogies, the article argues two original points in informal youth learning 1) an expanded definition of computing based on making grammars and the cultural practices of hip-hop, and 2) attention to cultural ecologies in designing and understanding computational STEM learning environments. 

Black males are often underrepresented in postsecondary education settings and frequently encounter many barriers in getting to college. Our aim in this qualitative investigation was to understand the precollege and college experiences of Black males who successfully enrolled in a postsecondary institution. Through a focus group interview, seven Black males in a living and learning community shared their experiences prior to and during enrollment at a highly selective, predominantly White institution. We used the grounded theory approach ( Strauss & Corbin, 1998 ) to analyze the focus group data and pinpoint thematic explanations of precollegiate and collegiate experiences of Black males. Based on the thematic findings, we offer specific recommendations on how school counselors can help Black males prepare and eventually matriculate in higher education. 

Remarkable advancements in high-throughput gene sequencing technologies have led to an exponential growth in the number of sequenced genomes. However, unavailability of highly parallel and scalablede novoassembly algorithms have hindered biologists attempting to swiftly assemble high-quality complex genomes. Popularde Bruijngraph assemblers, such as IDBA-UD, generate high-quality assemblies by iterating over a set ofk-values used in the construction of de Bruijn graphs (DBG). However, this process ofsequentiallyiterating from small to largek-values slows down the process of assembly. In this paper, we propose ScalaDBG, which metamorphoses this sequential process, building DBGs for each distinctk-value in parallel. We develop an innovative mechanism to “patch” a higherk-valued graph with contigs generated from a lowerk-valued graph. Moreover, ScalaDBG leverages multi-level parallelism, by both scaling up on all cores of a node, and scaling out to multiple nodessimultaneously. We demonstrate that ScalaDBG completes assembling the genome faster than IDBA-UD, but with similar accuracy on a variety of datasets (6.8X faster for one of the most complex genome in our dataset).

 

A key feature of engineering design is collaborative, deliberate decision making that takes into account information about design options. K‐12 students need opportunities for this kind of decision making if they are to meet the learning standards for engineering set out in the Next Generation Science Standards.

This qualitative study sought to propose and operationalize a definition of reflective decision‐making among elementary students. We investigated how urban elementary students enact reflective decision‐making in a formal engineering design curriculum.

We used naturalistic inquiry methodology and video recorded seven Engineering is Elementary design challenges in four classrooms. Students worked in small teams, and we focused on their planning and redesign phases. Maximum variation sampling, constant comparative analysis, and microethnographic accounts demonstrated the diversity of resources students utilized in their decision making.

In student discourse, we found evidence for six reflective decision‐making elements: articulating multiple solutions, evaluating pros and cons, intentionally selecting a solution, retelling the performance of a solution, analyzing a solution according to evidence, and purposefully choosing improvements. The discourse patterns used to enact these elements both supported and interfered with students' achievement of design goals.

Our results suggest that during engineering design tasks, young learners working in small teams can respond productively to opportunities to engage in sophisticated discourse. However, further work is needed on tools and strategies that support reflective decision‐making by all students during engineering design in elementary school.