523 research outputs found

    Researching PDS Initiatives to Promote Social Justice Across the Educational System

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    The examples and data shared in this chapter provide evidence that our comprehensive mission to understand and impact issues of social justice and equity within education is being achieved as the PDS Partnership continues to improve K-16 teaching and learning and enhance the teaching profession across all levels of education. The major implication of our findings is that systemic reform is achievable and the outcomes can be exceptionally rewarding. Of course, such initiatives require time, continuous effort, resources, broad-based participation of all stakeholders, and a sense of need for change. Developing human capital across the educational continuum requires a commitment to providing both support (professional development) and pressure (accountability) for all participants. Individual action plans (see appendix 1), documentation logs, and peer collaborative mentoring feedback reports indicate that participants at all levels of the educational system implemented new, effective, and equitable teaching strategies when provided with support and pressure to do so. Early partnership efforts to encourage faculty to embrace an equity agenda. in the late 1990s, fell short due to a lack of accountability. When given the opportunity to choose improvement strategies, faculty members tended to implement general teaching strategies that did not require them to step out of their comfort zones (e.g., using wait time or a ticket out strategy). Later partnership efforts, starting in 2004, placed emphasis on increasing the learning outcomes for culturally and linguistically diverse students, requiring participants to complete individual action plans annually. Participants used these action plans to identify and report on specific equitable teaching strategies they were implementing in their courses. These plans were then reviewed and assessed bi-annually to track progress towards meeting identified goals. The data we have considered here indicate that within this model of support and pressure, the partnership provided continuous professional development and collaboration, giving PDS participants the tools and support they need to effect change. At the same time, participants were held accountable for implementing and reporting on the new strategies and resulting impacts. This accountability augmented their increased awareness of the need for change, which led participants to invest the time and effort needed and to assume ownership of reform initiatives. Ultimately, the PDS model served as an ideal vehicle to implement systemic change to ensure a more just and equitable education system, across the K- 12 through college continuum. The highly collaborative nature of effective PDS partnerships allowed for powerful relationships to develop and authentic learning to occur. Once partners established a collective vision to address issues of inequality within their schools and teacher education programs, there were endless opportunities to utilize the expertise across the partnership and to leverage the momentum built as participants realized the impact of their actions

    Seasonal control of Petermann Gletscher ice-shelf melt by the ocean's response to sea-ice cover in Nares Strait

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    Petermann Gletscher drains ~4% of the Greenland ice sheet (GrIS) area, with ~80% of its mass loss occurring by basal melting of its ice shelf. We use a high-resolution coupled ocean and sea-ice model with a thermodynamic glacial ice shelf to diagnose ocean-controlled seasonality in basal melting of the Petermann ice shelf. Basal melt rates increase by ~20% in summer due to a seasonal shift in ocean circulation within Nares Strait that is associated with the transition from landfast sea ice to mobile sea ice. Under landfast ice, cold near-surface waters are maintained on the eastern side of the strait and within Petermann Fjord, reducing basal melt and insulating the ice shelf. Under mobile sea ice, warm waters are upwelled on the eastern side of the strait and, mediated by local instabilities and eddies, enter Petermann Fjord, enhancing basal melt down to depths of 200 m. The transition between these states occurs rapidly, and seasonal changes within Nares Strait are conveyed into the fjord within the same season. These results suggest that long-term changes in the length of the landfast sea-ice season will substantially alter the structure of Petermann ice shelf and its contribution to GrIS mass loss

    Distinct Frontal Ablation Processes Drive Heterogeneous Submarine Terminus Morphology

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    An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union.Calving and submarine melt drive frontal ablation and sculpt the ice face of marine‐terminating glaciers. However, there are sparse observations of submarine termini, which limit estimates of spatially varying submarine melt. Here we present a detailed survey of a west Greenland glacier to reveal heterogeneity in submarine terminus morphology. We find that the majority of the terminus (~77%) is undercut, driven by calving in the upper water column and submarine melting at depth. The remaining ~23% of the terminus is overcut, driven by calving alone. We use observations of six subglacial discharge outlets, combined with a plume model, to estimate spatially varying discharge fluxes. While small discharge fluxes (<43 m3/s) feed numerous, deeply undercut outlets with subsurface plumes, ~70% of the net subglacial flux emerges at the terminus center, producing a vigorous, surface‐reaching plume. This primary outlet drives large, localized seasonal retreat that exceeds calving rates at secondary outlets

    Seasonality and buoyancy suppression of turbulence in the Bay of Bengal

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    Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters, 46(8), (2019):4346-4355, doi:10.1029/2018GL081577.A yearlong record from moored current, temperature, conductivity, and four mixing meters (χpods) in the northernmost international waters of the Bay of Bengal quantifies upper‐ocean turbulent diffusivity of heat (Kt) and its response to the Indian monsoon. Data indicate (1) pronounced intermittency in turbulence at semidiurnal, diurnal, and near‐inertial timescales, (2) strong turbulence above 25‐m depth during the SW (summer) and NE (winter) monsoon relative to the transition periods (compare Kt > 10−4 m2/s to Kt  ∼ 10−5 m2/s, and (3) persistent suppression of turbulence (Kt < 10−5 m2/s) for 3 to 5 months in the latter half of the SW monsoon coincident with enhanced near‐surface stratification postarrival of low‐salinity water from the Brahmaputra‐Ganga‐Meghna delta and monsoonal precipitation. This suppression promotes maintenance of the low‐salinity surface waters within the interior of the bay preconditioning the upper northern Indian Ocean for the next year's monsoon.This work was supported by the U.S. Office of Naval Research (ONR) Grants N00014‐14‐1‐0236 and N00014‐17‐1‐2472, and the Ocean Mixing and Monsoon program of the Indian Ministry of Earth Sciences. The deployment of the Woods Hole Oceanographic Institution mooring and RW and JTF were supported by ONR Grant N00014‐13‐1‐0453. The deployment and recovery of the mooring were carried out by RV Sagar Nidhi and RV Sagar Kanya, respectively, with the help of the crew and science parties. Thanks to National Institute of Ocean Technology (India) for buoy support. The authors acknowledge invaluable discussions with Johannes Becherer, Deepak Cherian, and Sally Warner at CEOAS, OSU, and Dipanjan Chaudhuri, J Sree Lekha, and Debasis Sengupta at CAOS, IISc. The authors thank two anonymous reviewers for their detailed reviews, which have helped sharpen many aspects of this paper. Data can be accessed as described in section S2.2019-10-0

    Observations and modeling of a hydrothermal plume in Yellowstone Lake

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    Author Posting. © American Geophysical Union, 20XX. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 46(12), (2019): 6435-6442, doi:10.1029/2019GL082523.Acoustic Doppler current profiler and conductivity‐temperature‐depth data acquired in Yellowstone Lake reveal the presence of a buoyant plume above the “Deep Hole” hydrothermal system, located southeast of Stevenson Island. Distributed venting in the ~200 × 200‐m hydrothermal field creates a plume with vertical velocities of ~10 cm/s in the mid‐water column. Salinity profiles indicate that during the period of strong summer stratification the plume rises to a neutral buoyancy horizon at ~45‐m depth, corresponding to a ~70‐m rise height, where it generates an anomaly of ~5% (−0.0014 psu) relative to background lake water. We simulate the plume with a numerical model and find that a heat flux of 28 MW reproduces the salinity and vertical velocity observations, corresponding to a mass flux of 1.4 × 103 kg/s. When observational uncertainties are considered, the heat flux could range between 20 to 50 MW.The authors thank Yellowstone National Park Fisheries and Aquatic Sciences, The Global Foundation for Ocean Exploration, and Paul Fucile for logistical support. This research was supported by the National Science Foundation grants EAR‐1516361 to R. S., EAR‐1514865 to K. L., and EAR‐1515283 to R. H. and J. F. All work in Yellowstone National Park was completed under an authorized Yellowstone research permit (YELL‐2018‐SCI‐7018). CTD and ADCP profiles reported in this paper are available through the Marine Geoscience Data System (doi:10.1594/IEDA/324713 and doi:10.1594/IEDA/324712, accessed last on 17 April 2019, respectively).2019-11-0

    In Vivo Transplantation of Human Intestinal Organoids Enhances Select Tight Junction Gene Expression

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    BACKGROUND: Short bowel syndrome is a potentially fatal condition with inadequate management options. Tissue-engineered small intestine (TESI) is a promising solution, but confirmation of TESI function will be crucial before human application. We sought to define intestinal epithelial barrier function in human intestinal organoid (HIO)-derived TESI. MATERIALS AND METHODS: HIOs were generated in vitro from human embryonic stem cells. After 1 mo, HIOs were collected for analysis or transplanted into the kidney capsule of immunocompromised mice. Transplanted HIOs (tHIOs) were harvested for analysis at 4 or 8 wk. Reverse transcription quantitative polymerase chain reaction and immunofluorescent staining were performed for tight junction components: claudin 3 (CLDN3), claudin 15 (CLDN15), occludin (OCLN), and zonula occludens-1, or tight junction protein-1 (TJP1/ZO-1). RESULTS: Four-week-old tHIOs demonstrated significantly (P \u3c 0.05) higher levels of CLDN15 (6x), OCLN (4x), and TJP1/ZO-1 (3x) normalized to GAPDH than in vitro HIOs. Eight-week-old tHIOs demonstrated significantly (P \u3c 0.05) higher expression levels of CLDN3 (26x), CLDN15 (29x), OCLN (4x), and TJP1/ZO-1 (5x) than in vitro HIOs. There was no significant difference in expression of these tight junction components between 4- and 8-week-old tHIOs. Immunofluorescent staining revealed the presence of claudin 3, claudin 15, occludin, and zonula occludens-1 in both in vitro HIOs and tHIOs; however, the morphology appeared more mature in tHIOs. CONCLUSIONS: In vitro HIOs have lower levels of tight junction mRNA, and tight junction proteins appear morphologically immature. Transplantation facilitates maturation of the HIOs and enhances select tight junction gene expression

    Distributed subglacial discharge drives significant submarine melt at a Greenland tidewater glacier

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    Submarine melt can account for substantial mass loss at tidewater glacier termini. However, the processes controlling submarine melt are poorly understood due to limited observations of submarine termini. Here at a tidewater glacier in central West Greenland, we identify subglacial discharge outlets and infer submarine melt across the terminus using direct observations of the submarine terminus face. We find extensive melting associated with small discharge outlets. While the majority of discharge is routed to a single, large channel, outlets not fed by large tributaries drive submarine melt rates in excess of 3.0 m d−1 and account for 85% of total estimated melt across the terminus. Nearly the entire terminus is undercut, which may intersect surface crevasses and promote calving. Severe undercutting constricts buoyant outflow plumes and may amplify melt. The observed morphology and melt distribution motivate more realistic treatments of terminus shape and subglacial discharge in submarine melt models
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