We report on the construction and characterization of a low-cost Mach–Zehnder optical interferometer in which quadrature signal detection is achieved by means of polarization control. The device incorporates a generic green laser pointer, home-built photodetectors, 3D-printed optical mounts, a circular polarizer extracted from a pair of 3D movie glasses, and a python-enabled microcontroller for analog-to-digital data acquisition. Components fit inside of a [Formula: see text] space and can be assembled on a budget of less than US$500. The device has the potential to make quadrature interferometry accessible and affordable for instructors, students, and enthusiasts alike.
more »
« less
Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher.
Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
-
-
more » « less
Abstract This exploratory paper highlights how problem‐based learning (PBL) provided the pedagogical framework used to design and interpret learning analytics from C
rystal Island: EcoJourneys , a collaborative game‐based learning environment centred on supporting science inquiry. In Crystal Island: EcoJourneys , students work in teams of four, investigate the problem individually and then utilize a brainstorming board, an in‐game PBL whiteboard that structured the collaborative inquiry process. The paper addresses a central question: how can PBL support the interpretation of the observed patterns in individual actions and collaborative interactions in the collaborative game‐based learning environment? Drawing on a mixed method approach, we first analyzed students' pre‐ and post‐test results to determine if there were learning gains. We then used principal component analysis (PCA) to describe the patterns in game interaction data and clustered students based on the PCA. Based on the pre‐ and post‐test results and PCA clusters, we used interaction analysis to understand how collaborative interactions unfolded across selected groups. Results showed that students learned the targeted content after engaging with the game‐based learning environment. Clusters based on the PCA revealed four main ways of engaging in the game‐based learning environment: students engaged in low to moderate self‐directed actions with (1) high and (2) moderate collaborative sense‐making actions, (3) low self‐directed with low collaborative sense‐making actions and (4) high self‐directed actions with low collaborative sense‐making actions. Qualitative interaction analysis revealed that a key difference among four groups in each cluster was the nature of verbal student discourse: students in the low to moderate self‐directed and high collaborative sense‐making cluster actively initiated discussions and integrated information they learned to the problem, whereas students in the other clusters required more support. These findings have implications for designing adaptive support that responds to students' interactions with in‐game activities.Practitioner notes What is already known about this topic
Learning analytic methods have been effective for understanding student learning interactions for the purposes of assessment, profiling student behaviour and the effectiveness of interventions.
However, the interpretation of analytics from these diverse data sets are not always grounded in theory and challenges of interpreting student data are further compounded in collaborative inquiry settings, where students work in groups to solve a problem.
What this paper adds
Problem‐based learning as a pedagogical framework allowed for the design to focus on individual and collaborative actions in a game‐based learning environment and, in turn, informed the interpretation of game‐based analytics as it relates to student's self‐directed learning in their individual investigations and collaborative inquiry discussions.
The combination of principal component analysis and qualitative interaction analysis was critical in understanding the nuances of student collaborative inquiry.
Implications for practice and/or policy
Self‐directed actions in individual investigations are critical steps to collaborative inquiry. However, students may need to be encouraged to engage in these actions.
Clustering student data can inform which scaffolds can be delivered to support both self‐directed learning and collaborative inquiry interactions.
All students can engage in knowledge‐integration discourse, but some students may need more direct support from teachers to achieve this.
-
Subcritical hydrothermal liquefaction uses high temperatures (270-350°C) and high pressures (80-173 bar) to produce bio-crude oils that can be upgraded to liquid transportation fuels. In this study, two strains of Galdieria sulphuraria, an acidophilic, mixotrophic red microalgae, were cultivated on effluent from primary settling tanks at a municipal wastewater treatment plant. Samples were concentrated to 5 and 10 wt.% slurries after harvest and converted by hydrothermal liquefaction in a 1.8 L batch reactor. Reaction conditions included temperatures of 310, 330 and 350°C, and hold times of 5, 30 and 60 minutes. Yields and product properties were compared to those of hydrothermal liquefaction of Galdieria sulphuraria grown on media. Total oil yields were low (11-18 wt.%) and char yields were high (28-36 wt.%) compared to those from HTL of the algae grown on media (27-35 wt.% oil and 10-13 wt.% char), likely due to the higher ash content and lower lipid content of the algae grown on wastewater. The bio-crude oil, char, and aqueous phase samples were characterized to complete mass, energy and nutrient balances to characterize the tradeoffs in the algae growth and conversion systems for energy and nutrient recovery.more » « less
-
more » « less
Abstract We provide a functional characterization of transcription factor NF-κB in protists and provide information about the evolution and diversification of this biologically important protein. We characterized NF-κB in two protists using phylogenetic, cellular, and biochemical techniques. NF-κB of the holozoan
Capsaspora owczarzaki (Co ) has an N-terminal DNA-binding domain and a C-terminal Ankyrin repeat (ANK) domain, and its DNA-binding specificity is more similar to metazoan NF-κB proteins than to Rel proteins. Removal of the ANK domain allowsCo -NF-κB to enter the nucleus, bind DNA, and activate transcription. However, C-terminal processing ofCo -NF-κB is not induced by IκB kinases in human cells. OverexpressedCo -NF-κB localizes to the cytoplasm inCo cells.Co -NF-κB mRNA and DNA-binding levels differ across threeCapsaspora life stages. RNA-sequencing and GO analyses identify possible gene targets ofCo -NF-κB. Three NF-κB-like proteins from the choanoflagellateAcanthoeca spectabilis (As ) contain conserved Rel Homology domain sequences, but lack C-terminal ANK repeats. All threeAs -NF-κB proteins constitutively enter the nucleus of cells, but differ in their DNA-binding abilities, transcriptional activation activities, and dimerization properties. These results provide a basis for understanding the evolutionary origins of this key transcription factor and could have implications for the origins of regulated immunity in higher taxa.
