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  1. ABSTRACT We conducted a drift-scan observation campaign using the 305-m Arecibo telescope in 2020 January and March when the observatory was temporarily closed during the intense earthquakes and the initial outbreak of the COVID-19 pandemic, respectively. The primary objective of the survey was to search for fast radio transients, including fast radio bursts (FRBs) and rotating radio transients (RRATs). We used the seven-beam ALFA receiver to observe different sections of the sky within the declination region ∼(10°–20°) on 23 nights and collected 160 h of data in total. We searched our data for single-pulse transients, of covering up to a maximummore »dispersion measure of 11 000 pc cm−3 at which the dispersion delay across the entire bandwidth is equal to the 13-s transit length of our observations. The analysis produced more than 18 million candidates. Machine learning techniques sorted the radio frequency interference and possibly astrophysical candidates, allowing us to visually inspect and confirm the candidate transients. We found no evidence for new astrophysical transients in our data. We also searched for emission from repeated transient signals, but found no evidence for such sources. We detected single pulses from two known pulsars in our observations and their measured flux densities are consistent with the expected values. Based on our observations and sensitivity, we estimated the upper limit for the FRB rate to be <2.8 × 105 sky−1 d−1 above a fluence of 0.16 Jy ms at 1.4 GHz, which is consistent with the rates from other telescopes and surveys.« less
    Free, publicly-accessible full text available November 17, 2022
  2. Free, publicly-accessible full text available September 28, 2022
  3. null (Ed.)
    Free, publicly-accessible full text available October 1, 2022
  4. Elementary school teachers are increasingly looking to incorporate computational thinking (CT) into their practice. Unlike middle and high school where CT is often integrated into a single subject, elementary school teachers have the unique opportunity to integrate CT across multiple content areas. However, there is little research on the in-platform supports elementary teachers need to accomplish this integration successfully. To investigate this integration, we are iteratively developing a narrative-centered learning environment to facilitate learning outcomes in physical science via the creation of digital narratives that elicit CT. The learning environment enables students to use their science understanding to propose amore »solution to a problem through story creation using custom narrative-centered programming blocks that set a story’s scene, selects characters, and controls the story’s unfolding dialogue and actions. We have engaged with four upper elementary teachers to gather their perspectives on the usability of the learning environment and input on future design iterations. In this paper, we report results from a focus group study with the teachers that examines their perceptions on whether and how the learning environment facilitates story creation and if the learning environment provides learning supports for integrated science, language arts, and CT. Initial results suggest that teachers found the environment to be engaging and supportive of students’ creativity.« less
  5. This method for separating coral tissues from algal endosymbiont (Symbiodiniaceae) for stable isotope analysis is modified from previously published methods (Hughes et al. 2010). There are three parts to preparing coral samples for stable carbon and nitrogen isotope analysis: 1) airbrush to remove coral tissue and algal cells from skeleton and store at -80 °C until ready to separate, 2) separate the coral tissue from the algal cells through centrifugation and filtering, and 3) dry and pack separated tissues into tin capsules for analysis in a stable isotope ratio mass spectrometer. This method was modified from Hughes et al. (2010)more »by James Price with the assistance of Alex Smith and Kerri Dobson and with the guidance of Andréa Grottoli at The Ohio State University.« less
  6. Existing three-dimensional (3D) culture techniques are limited by trade-offs between throughput, capacity for high-resolution imaging in living state, and geometric control. Here, we introduce a modular microscale hanging drop culture where simple design elements allow high replicates for drug screening, direct on-chip real-time or high-resolution confocal microscopy, and geometric control in 3D. Thousands of spheroids can be formed on our microchip in a single step and without any selective pressure from specific matrices. Microchip cultures from human LN229 glioblastoma and patient-derived mouse xenograft cells retained genomic alterations of originating tumors based on mate pair sequencing. We measured response to drugsmore »over time with real-time microscopy on-chip. Last, by engineering droplets to form predetermined geometric shapes, we were able to manipulate the geometry of cultured cell masses. These outcomes can enable broad applications in advancing personalized medicine for cancer and drug discovery, tissue engineering, and stem cell research.« less
  7. Free, publicly-accessible full text available March 1, 2023
  8. In an effort to infuse computational thinking practices in upper elementary science, and to promote positive student dispositions toward STEM, this project investigates a new narrative-centered maker environment involving: 1) problem-based learning research and modeling of physical science concepts, 2) application of learned concepts to original digital stories created using block-based programming, and 3) further communication of science understanding through play with fabricated story sets and characters reflective of narratives.
  9. Abstract We report TeV gamma-ray observations of the ultra-high-energy source MGRO J1908+06 using data from the High Altitude Water Cherenkov Observatory. This source is one of the highest-energy known gamma-ray sources, with emission extending past 200 TeV. Modeling suggests that the bulk of the TeV gamma-ray emission is leptonic in nature, driven by the energetic radio-faint pulsar PSR J1907+0602. Depending on what assumptions are included in the model, a hadronic component may also be allowed. Using the results of the modeling, we discuss implications for detection prospects by multi-messenger campaigns.
    Free, publicly-accessible full text available March 31, 2023