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Lifelong learning plays an important role in achieving success in one’s professional life. Engaging students in metacognition assists in the development of their lifelong learning abilities. Instructors can integrate reflection activities in their courses to provide multiple opportunities to students for metacognitive engagement. During reflection, students regulate their cognition by engaging themselves in three dimensions of metacognition: Planning, Monitoring, and Evaluating. Reflection is a complex process, and it takes time to reach the level of critical reflection. The purpose of the study was to investigate the change in students' level of engagement in three dimensions of metacognition when reflecting on the third and tenth-week assignments of the environmental engineering course. Data collection took place in the Fall of 2023 at a large Midwest University. Students’ responses to the assigned reflection prompts for each dimension were coded for their level of engagement in each element of the three dimensions using a revised prior coding scheme. Results showed that for both assignments, students' responses were mainly at the vague level for all elements of the three dimensions, indicating students' superficial engagement in the reflection activity. Recommendations for instructors are provided to improve students' understanding of the reflection activity and their level of engagement in the three dimensions of metacognition. 

Wireless links at sub-THz bands require low-SWaP SDR modems. We report early design experimentation of an SDR operating in the 130–150 GHz band, with ASK/BPSK/QPSK modulation on I/Q channels, at a maximum data rate of 128 Mbps. The design utilizes 110–170 GHz front-ends from Virginia Diodes, and Xilinx RF-SoC ZCU-111 for DSP operations. A 1 GHz baseband example at 145.5 GHz is provided. The experiment uses horn antennas with 21 dB gain. The SNR is about 40 dB without cross correlation gain in the detector which provides an additional 15 dB in link margin. Real-time bit rate of 128 Mbps is achieved. Example applications include vehicle-to-vehicle, vehicle-to-infrastructure, backhaul, device-to-aerostat. This paper provides a platform from which further design work will lead to increased data rate and/or range, and enhance security through encryption. Future designs will facilitate digital interfaces, such as, ethernet, AXI, PCIe and USB-C. 

Self-regulation, a skillset involving taking charge of one’s own learning processes, is crucial for workplace success. Learners develop self-regulation skills through reflection where they recognize weaknesses and strengths by employing metacognitive strategies: planning, monitoring, and evaluating. Use of anchors assists learners’ engagement in reflection. The purpose of this work was to gain insight into students’ use of anchors when reflecting on their learning. The two research questions were: (1) To what extent do students link their self-evaluation and learning objective (LO) self-ratings to their reflections? and (2) What dimensions and level of metacognitive strategies do students use in their self-evaluation of and reflections on weekly problem-solving assignments? Data were upper-division engineering students’ anchors (self- evaluations, LO self-ratings) and reflection responses for one assignment. Self-evaluations and reflections were analyzed for the presence of references to LOs. The number of students who linked the anchors to their reflection were tabulated. Additionally, a revised a priori coding scheme was applied to students’ written work to determine type and level of metacognitive strategies employed. Few students linked both anchors to their reflections. Students employed low to medium levels of the metacognitive strategies in their self-evaluations and reflections, even when they linked their anchors and reflections. The evaluating strategy dominated in the self- evaluations, while planning and monitoring dominated in the reflections. Students have limited understanding of the use of anchors to guide their reflection responses. Students overall level of engagement in the metacognitive strategies indicates a need for formal instruction on reflection. 

The red hypergiant VY CMa is famous for its very visible record of high-mass-loss events. Recent CO observations with the Atacama Large Millimeter/submillimeter Array (ALMA) revealed three previously unknown large-scale outflows (Singh et al). In this paper, we use the CO maps to investigate the motions of a cluster of four clumps close to the star, not visible in the optical or infrared images. We present their proper motions measured from two epochs of ALMA images and determine the line-of-sight velocities of the gas in emission at the clumps. We estimate their masses and ages, or time since ejection, and conclude that all four were ejected during VY CMa’s active period in the early 20th century. Together with two additional knots observed with the Hubble Space Telescope, VY CMa experienced at least six massive outflows during a 30 yr period, with a total mass lost ≥0.07M_⊙. The position–velocity map of the¹²CO emission reveals previously unnoticed attributes of the older outer ejecta. In a very narrow range of Doppler velocities,¹²CO absorption and emission causes some of this outer material to be quite opaque. At those frequencies the inner structure is hidden and we see only emission from an extended outer region. This fact produces a conspicuous but illusory dark spot if one attempts to subtract the continuum in a normal way.

 

TheJ= 2 → 1 transition of CO near 230 GHz and theJ= 3 → 2 line of HCN at 265 GHz have been imaged in the envelope of the red hypergiant star, VY Canis Majoris (VY CMa), using the Atacama Large Millimeter Array (ALMA) with angular resolutions 0.″2–1.″5; single-dish data were added to provide sensitivity up to 30″. These images reveal a far more complex envelope, with previously unseen outflows extending 4″–9″ from the star. These new structures include an arc-like outflow with an angular separation of ∼9″ northeast from the stellar position (“NE Arc”), twin fingerlike features approximately 4″ to the north/northeast (“NE Extension”), and a roughly spherical region observed ∼7″ E of the star (“E Bubble”). The NE Arc appears to be decelerating from base (V_LSR∼ 7 km s⁻¹) to tip (V_LSR∼ 18 km s⁻¹), while the NE Extension is blueshifted withV_LSR∼ −7 km s⁻¹. Among the new features, HCN is only detected in the NE Arc. In addition, known structures Arc 1, Arc 2, and NW Arc, as well as other features closer to the star, are closely replicated in CO, suggesting that the gas and dust are well mixed. The CO spectra are consistent with the kinematic picture of VY CMa derived from HST data. Arc 2, however, has added complexity. Preliminary results from CO suggest¹²C/¹³C ∼ 22–38 across the envelope. The additional presence of at least three major episodic mass ejection events significantly broadens the current perspective of the envelope structure and mass-loss history of VY CMa.

 

Boron carbide (B4C) has been well studied both theoretically and experimentally in its bulk form due to its exceptional hardness and use as a high-temperature thermoelectric. However, the properties of its two-dimensional nanosheets are not well established. In this paper, using van der Waals-corrected density-functional theory simulations, we show that bulk B4C can be cleaved along different directions to form B4C nanosheets with low formation energies. We find that there is minimal dependence of formation energies on cleavage planes and surface terminations, even though the bulk is not van der Waals layered. This anomalous stability of B4C nanosheets is found to be a result of surface reconstructions that are unique to B-rich systems. While the density of states of the bulk B4C indicate that it is a semiconductor, the B4C nanosheets are found to be predominantly metallic. We attribute this metallic behavior to a redistribution of charges on the surface bonds of the films. The Seebeck coefficients of the B4C films remain comparable to those of the bulk and are nearly constant as a function of temperature. Our results provide guidance for experimental synthesis efforts and future application of B4C nanosheets in nanoelectronic and thermoelectric applications.

 

A sensitive (1σrms ≤ 3 mK; 2 MHz resolution) 1 mm spectral survey (214.5–285.5 GHz) of the envelope of the oxygen-rich supergiant star NML Cygni (NML Cyg) has been conducted using the 10 m Submillimeter Telescope of the Arizona Radio Observatory. These data represent the first spectral line survey of NML Cyg and are complementary to a previous 1 mm survey of the envelope of a similar hypergiant, VY Canis Majoris (VY CMa). The complete NML Cyg data set is presented here. In the survey, 104 emission lines were observed, arising from 17 different molecules and 4 unidentified features. Many of the observed features have complex line profiles, arising from asymmetric outflows characteristic of hypergiant stars. While most of the lines in the survey arise from SiO, SO, SO₂, and SiS, CO had the strongest emission. Five other C-bearing species are identified in the survey (HCN, CN, HCO⁺, CS, and HNC), demonstrating an active carbon chemistry despite the O-rich environment. Moreover, NS was observed, but not NO, although favorable transitions of both molecules lie in the surveyed region. Sulfur chemistry appears to be prominent in NML Cyg and plays an important role in the collimated outflows. The refractory species observed, NaCl and AlO, have narrow emission lines, indicating that these molecules do not reach the terminal expansion velocity. NaCl and AlO likely condense into dust grains at r < 50R_*. From NaCl, the chlorine isotope ratio was determined to be³⁵Cl/³⁷Cl = 3.85 ± 0.30.

 

The millimeter-wave spectrum of the SiP radical (X²Π_i) has been measured in the laboratory for the first time using direct-absorption methods. SiP was created by the reaction of phosphorus vapor and SiH₄in argon in an AC discharge. Fifteen rotational transitions (J+ 1 ←J) were measured for SiP in the Ω = 3/2 ladder in the frequency range 151–533 GHz, and rotational, lambda doubling, and phosphorus hyperfine constants determined. Based on the laboratory measurements, SiP was detected in the circumstellar shell of IRC+10216, using the Submillimeter Telescope and the 12 m antenna of the Arizona Radio Observatory at 1 mm and 2 mm, respectively. Eight transitions of SiP were searched: four were completely obscured by stronger features, two were uncontaminated (J= 13.5 → 12.5 and 16.5 → 15.5), and two were partially blended with other lines (J= 8.5 → 7.5 and 17.5 → 16.5). The SiP line profiles were broader than expected for IRC+10216, consistent with the hyperfine splitting. From non-LTE radiative transfer modeling, SiP was found to have a shell distribution with a radius ∼300R_*, and an abundance, relative to H₂, off∼ 2 × 10⁻⁹. From additional modeling, abundances of 7 × 10⁻⁹and 9 × 10⁻¹⁰were determined for CP and PN, respectively, both located in shells at 550–650R_*. SiP may be formed from grain destruction, which liberates both phosphorus and silicon into the gas phase, and then is channeled into other P-bearing molecules such as PN and CP.