Instructional Practices for Addressing Computer Science Standards: Using Computer Kits in Preservice Teacher Education

This article examines the instructional practices used to teach the computer science (CS) standard of computer devices and systems to undergraduate preservice teachers (PSTs). With computer science education (CSE) gaining an international focus, there is a need to explore a variety of instructional practices used to teach these topics. This descriptive, exploratory case study presents an examination of the instructional practices used in a CSE licensure course. In this study, the instructor utilised two commercially available computer kits to provide hands-on, learner-centred learning experiences for PSTs. PSTs perceived these kits to be valuable for learning about computing devices and systems topics and for teaching these topics in their future classrooms. Additionally, results showed that PSTs considered the usability, grade level and ability of the kits to build interest in CS when reflecting on their future use. Limitations to the instructional practices included a lack of transfer to subject areas outside of CS and a lack of focus on the integration between hardware and software

Discovery of a Double Blue Straggler Sequence in M15: New Insight into the Core-collapse Process

In this paper we report the discovery of a double blue straggler star (BSS) sequence in the core of the core-collapsed cluster M15 (NGC 7078). We performed a detailed photometric analysis of the extremely dense core of the cluster using a set of images secured with the Advanced Camera for Survey in the High Resolution Channel mode on board the Hubble Space Telescope. The proper combination of the large number of single frames in the near-UV (F220W), and blue (F435W) filters allowed us to perform a superb modeling of the point-spread function and an accurate deblending procedure. The color–magnitude diagram revealed the presence of two distinct parallel sequences of blue stragglers. In particular, the blue BSS sequence is characterized by the intriguing presence of two different branches. The first branch appears extremely narrow, it extends up to 2.5 mag brighter than the cluster main-sequence turnoff (MS-TO) point, and it is nicely reproduced by a 2 Gyr old collisional isochrone. The second branch extends up to 1.5 mag from the MS-TO and it is reproduced by a 5.5 Gyr old collisional isochrone. Our observations suggest that each of these branches is mainly constituted by a population of nearly coeval collisional BSSs of different masses generated during two episodes of high collisional activity. We discuss the possibility that the oldest episode corresponds to the core-collapse (CC) event (occurred about 5.5 Gyr ago), while the most recent one (occurred about 2 Gyr ago) is associated with a core oscillation in the post-CC evolution. The discovery of these features provides further strong evidence in support of the connection between the BSS properties and globular cluster dynamical evolution, and it opens new perspectives on the study of CC and post-CC evolution

Key considerations when using health insurance claims data in advanced data analyses: An experience report

Health claims have become a popular source of data for healthcare analytics, with numerous applications ranging from disease burden estimation and policy evaluation to drug event detection and advanced predictive analytics. Independent of the application, a researcher utilizing claims information will likely encounter challenges in using the data, which include dealing with several coding systems and coding irregularities. We highlight some of these challenges and approaches for successful analysis that may reduce implementation time and help in avoiding common pitfalls. We describe the experiences of a group of academic researchers in using an extensive seven-year repository of US medical and pharmaceutical claims data in a research study, and it provides an overview of the challenges encountered with handling claims records for data analysis while sharing suggestions on how to address these challenges. To illustrate our experiences, we use the example of dening episodes of care for a bundled payment reimbursement system in the US context

A Family Picture: Tracing the Dynamical Path of the Structural Properties of Multiple Populations in Globular Clusters

We studied the spatial distributions of multiple stellar populations (MPs) in a sample of 20 globular clusters (GCs) spanning a broad range of dynamical ages. The differences between first-population (FP) and second-population (SP) stars were measured by means of the parameter A +, defined as the area enclosed between their cumulative radial distributions. We provide the first purely observational evidence of the dynamical path followed by MPs from initial conditions toward a complete FP–SP spatial mixing. Less dynamically evolved clusters have SP stars more centrally concentrated than FPs, while in more dynamically evolved systems the spatial differences between FP and SP stars decrease and eventually disappear. By means of an appropriate comparison with a set of numerical simulations, we show that these observational results are consistent with the evolutionary sequence expected by the long-term dynamical evolution of clusters forming with an initially more centrally concentrated SP subsystem. This result is further supported by the evidence of a trend between A + and the stage of GC dynamical evolution inferred by the ratio between the present-day and the initial mass of the cluster

Management and Effects of In-Store Promotional Displays

Problem denition: We examine a brick-and-mortar retailer's choice of which product to include in a promotional display (e.g., an \endcap" display). The display provides a visibility advantage to both the featured product and its category, but it also has consequences for customer trac and substitution. Academic / practical relevance: While there has been considerable academic interest in the assortment planning problem (which products to oer?) and in the shelf-space allocation problem (how much space to devote to each product?), little attention has been paid to the problem of where to place products in the store. Promotional display choice can serve as a powerful demand-shaping lever for retailers. A good understanding of this problem can also facilitate a retailer's negotiations with manufacturers. Methodology: We develop analytical insights using a problem formulation based on a nested multinomial logit (NMNL) model of customer choice. Results: When choosing a promotional product from a xed category, the only possible optimal choices for promotional display lie along an effecient set" drawn in terms of product popularities and margins. The optimal choice along the frontier depends on a quantity we call "aisle attractiveness" that depends on several category-level parameters. The value of the display to a category pivots on whether the display's role is primarily to expand demand for the category or to shape substitution within the category. Managerial implications: Our work provides guidance for how retailers can use and value promotional displays eectively. We highlight the importance of considering externalities of a display decision on store trac and demand for other products

PQS Signaling for More than a Quorum: the Collective Stress Response Protects Healthy Pseudomonas aeruginosa Populations

In this issue, Bru et al. connect Pseudomonas aeruginosa PQS signaling secretion during stress response to swarming behavior (J.-L. Bru, B. Rawson, C. Trinh, K. Whiteson, et al., J Bacteriol 201:e00383-19, 2019, https://doi.org/10.1128/JB.00383-19). Phage-infected or antibiotic-treated bacterial cells secrete PQS to repel healthy, unexposed cells away from the source of the stress. Thus, the collective stress response mechanism driven by PQS signaling influences spatial organization and population dynamics in P. aeruginosa that may provide competitive advantages in certain niches

Evidence for a GPR18 Role in Chemotaxis, Proliferation, and the Course of Wound Closure in the Cornea

PURPOSE: We previously showed that cannabinoid-related GPR18 receptors are present in murine corneal epithelium but their function remains unknown. The related CB1 receptors regulate corneal healing, possibly via chemotaxis. We therefore examined a potential role for GPR18 in corneal epithelial chemotaxis and wound healing. METHODS: We examined GPR18 mRNA and protein expression in cornea. We additionally examined the GPR18 action in cultured bovine corneal epithelial cells (bCECs) using Boyden and tracking assays, as well as proliferation and signaling. Finally, we examined wound closure in murine corneal explants. RESULTS: GPR18 mRNA was upregulated with injury in mouse cornea. GPR18 protein was present in basal epithelial cells of the mouse and cow, and redistributed to the wound site upon injury. GPR18 ligand N-arachidonoylglycine (NAGly) induced bCEC chemotaxis. The endocannabinoid arachidonoylethanolamine (AEA) also induced chemotaxis via fatty acid amide hydrolase (FAAH) mediated metabolism to NAGly. GPR18 receptor activation additionally induced bCEC proliferation. In an explant model, the GPR18 antagonist O1918 slowed corneal epithelial cell migration and the rate of corneal wound closure. CONCLUSIONS: Corneal GPR18 activation induced both chemotaxis and proliferation in CECs in vitro, and impacted wound healing. GPR18 may contribute to the maintenance of corneal integrity

Spatially Variable Increase in Rock Uplift in the Northern U.S. Cordillera Recorded in the Distribution of River Knickpoints and Incision Depths

Landscape evolution is driven by factors like tectonics and climate, and unraveling such factors can reveal the history recorded in landscape morphology. The northern U.S. Cordillera features many potential drivers, such as the Yellowstone plume, the extrusion of a large igneous province, and the drainage of large lakes. Among this complex geologic history, the drivers of transient incision in the Clearwater and Salmon watersheds of central Idaho are not well understood. To constrain the pattern of regional incision, we analyze the morphologies of 80 individual tributaries underlain by single lithologies. From north to south across our study area, knickpoint elevations increase from about 800 to 2,200 m, and incision depths increase from about 300 to 1,200 m. We use both numerical and analytical models to demonstrate that such a gradient could represent spatial variations in rock uplift. These findings suggest that transience is driven by a spatially variable increase in rock uplift that has disrupted a low‐relief paleolandscape, and the high steepness values of main drainages suggest that high rock‐uplift rates are still maintained to the present. Changes in rock uplift may be related to interactions between the Yellowstone plume and the lithosphere, although base level fall from the drainage of the Lake Idaho down the proto‐Snake River may be superimposed over these patterns in rock uplift. We show that careful, quantitative analyses of river profiles in geologically complex regions can differentiate between the influences of rock uplift and far‐field base level changes

Using Inclusive Sport for Social Change in Malawi, Africa

This report draws upon the first year of the Youth Enrichment through Sports (YES)-Africa cooperative agreement focused on sport for social change involving five sub-Saharan African countries. The YES-Africa program, funded by the U.S. Department of State, is designed to enhance cross-cultural understanding and collaboration between individuals and nations. The YESAfrica Malawi exchange builds capacity for sport leaders in Malawi to implement inclusive sport and recreation for youth with disabilities. This case study employs a content analysis of international and national legislative and policy agendas addressing inclusion of youth with disabilities within the context of sport, and explores barriers to policy implementation through interviews with seven key stakeholders and a review of structured field notes. Findings suggest that while Malawi’s legislative and policy landscape appears to adequately address the needs of youth with disabilities broadly, implementation is limited by social, physical, and socio-environmental barriers. We explore contributions of TR professionals in addressing key policy priorities in developing countries

First constraint on coherent elastic neutrino-nucleus scattering in argon

Coherent elastic neutrino-nucleus scattering (CEvNS) is calculated to be the dominant neutrino scattering channel for neutrinos of energy $E_ν$ < 100 MeV . We report a limit for this process from data collected in an engineering run of the 29 kg CENNS-10 liquid argon detector located 27.5 m from the pion decay-at-rest neutrino source at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) with 4.2 × 10$^{22}$ protons on target. The dataset provided constraints on beam-related backgrounds critical for future measurements and yielded < 7.4 candidate CEvNS events which implies a cross section for the process, averaged over the SNS pion decay-at-rest flux, of < 3.4 × 10$^{−39}$ cm$^2$ , a limit within twice the Standard Model prediction. This is the first limit on CEvNS from an argon nucleus and confirms the earlier CsI[Na] nonstandard neutrino interaction constraints from the collaboration. This run demonstrated the feasibility of the ongoing experimental effort to detect CEvNS with liquid argon