7,819 research outputs found
Recommended from our members
Effect of Tides and Currents on UAV-Based Detection of Giant Kelp Canopy
Satellite and aerial imagery have been used extensively for mapping the abundance and distribution of giant kelp (Macrocystis pyrifera) in southern California. While tides and currents have been shown to affect the amount of floating kelp canopy on the water surface, there have been no quantifications of how these processes can bias remotely sensed kelp estimates in this region. We used unmanned aerial vehicles (UAVs) to map fine-scale changes in canopy area due to tidal height and current speed at both Palos Verdes, CA and Santa Barbara, CA. Additionally, we collected a biweekly time series of kelp canopy area in Palos Verdes over the course of a year to monitor fine-scale, intra-seasonal changes in canopy coverage. Our automated method for detecting kelp canopy in color and multispectral UAV imagery was highly accurate (over 84% and 98%, respectively) in classifying exemplary kelp and water pixels across a range of weather, ocean, and illumination conditions. Increases in tidal height of 1 m reduced the amount of floating kelp canopy by 15% to 32%. Current speeds are generally low in southern California and had no statistically significant effect on apparent bed size. However, increases in current speeds of 0.1 m/s reduced the amount of floating kelp canopy by over 31%. Tidal height and current speed can introduce significant variability to estimates of kelp abundance, but the magnitude of this variability is region specific. The biweekly time series displayed intra-annual variability typical of giant kelp, with a relatively gradual decline in kelp canopy in late summer corresponding with high sea surface temperatures, a rapid decline in the winter associated with wave disturbance, and a gradual recovery in the spring of the following year. The time series was also able to capture intra-seasonal changes in kelp canopy area that would have gone undetected in an annual or quarterly dataset, namely an increase in area to about half of the maximum in the late fall before wave events began
Hyper (In)visibility: Trans-ing the Politics of Visibility
This project responds to an ongoing demand by the LGBTQ+ activist community to center the “on-the-ground” work of queer artists and activists of color in academic theoretical and political work. More specifically, I respond to this call by considering how the work of Alok Vaid-Menon and Travis Alabanza, trans-femme of color activists and artists, interrogates and contests mainstream visibility-based political praxis alongside canonical works of Black feminist thought, postcolonial theory, queer theory and critical race theory. I compile and analyze three archives of data in taking on this project: academic work on the politics of visibility since the liberation movements of the 1960s, public documents - such as online web pages, social media posts, and press releases - reflecting the political thought and praxis of mainstream progressive organizations since 2009, then works of Black and brown trans-femme artists and activists Alok Vaid-Menon and Travis Alabanza. By examining the relationships between these archives, I articulate in a historically and theoretically rigorous way the challenge posed by trans-femmes of the dominant political paradigm of visibility-as-justice, finding additionally how this challenge stands in relation to the recent history of institutionalized academic work on visibility
Study of active vibration isolation systems for severe ground transportation environments
Active vibration isolation systems for severe ground transportation loading environment
K-12 Mobile learning
Mobile devices have been the focus of a push in many nations and internationally as part of efforts to achieve greater literacy and numeracy among students. Research has shown a strong link between Internet usage, the spread of broadband in a country, and its GDP. Those coun - tries that are the highest performing educationally already integrate mobile devices in their education. This paper synthesizes empirical research on mobile devices from 2010 to 2013 in K-12 schools by focusing on studies that demonstrate emerging themes in this area. It is also clear that the pedagogy needed to be successful in creating positive outcomes in the use of technology has to be student-centered with the aim of personalizing the learning experience. Research found that students could become collaborators in designing their own learning process. As students become independent learners, they become more prepared in the skills needed for college and in their careers
Recommended from our members
Climate-driven regime shifts in a mangrove-salt marsh ecotone over the past 250 years.
Climate change is driving the tropicalization of temperate ecosystems by shifting the range edges of numerous species poleward. Over the past few decades, mangroves have rapidly displaced salt marshes near multiple poleward mangrove range limits, including in northeast Florida. It is uncertain whether such mangrove expansions are due to anthropogenic climate change or natural climate variability. We combined historical accounts from books, personal journals, scientific articles, logbooks, photographs, and maps with climate data to show that the current ecotone between mangroves and salt marshes in northeast Florida has shifted between mangrove and salt marsh dominance at least 6 times between the late 1700s and 2017 due to decadal-scale fluctuations in the frequency and intensity of extreme cold events. Model projections of daily minimum temperature from 2000 through 2100 indicate an increase in annual minimum temperature by 0.5 °C/decade. Thus, although recent mangrove range expansion should indeed be placed into a broader historical context of an oscillating system, climate projections suggest that the recent trend may represent a more permanent regime shift due to the effects of climate change
Automated satellite remote sensing of giant kelp at the Falkland Islands (Islas Malvinas)
© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Houskeeper, H. F., Rosenthal, I. S., Cavanaugh, K. C., Pawlak, C., Trouille, L., Byrnes, J. E. K., Bell, T. W., & Cavanaugh, K. C. Automated satellite remote sensing of giant kelp at the Falkland Islands (Islas Malvinas). Plos One, 17(1), (2022): e0257933, https://doi.org/10.1371/journal.pone.0257933.Giant kelp populations that support productive and diverse coastal ecosystems at temperate and subpolar latitudes of both hemispheres are vulnerable to changing climate conditions as well as direct human impacts. Observations of giant kelp forests are spatially and temporally uneven, with disproportionate coverage in the northern hemisphere, despite the size and comparable density of southern hemisphere kelp forests. Satellite imagery enables the mapping of existing and historical giant kelp populations in understudied regions, but automating the detection of giant kelp using satellite imagery requires approaches that are robust to the optical complexity of the shallow, nearshore environment. We present and compare two approaches for automating the detection of giant kelp in satellite datasets: one based on crowd sourcing of satellite imagery classifications and another based on a decision tree paired with a spectral unmixing algorithm (automated using Google Earth Engine). Both approaches are applied to satellite imagery (Landsat) of the Falkland Islands or Islas Malvinas (FLK), an archipelago in the southern Atlantic Ocean that supports expansive giant kelp ecosystems. The performance of each method is evaluated by comparing the automated classifications with a subset of expert-annotated imagery (8 images spanning the majority of our continuous timeseries, cumulatively covering over 2,700 km of coastline, and including all relevant sensors). Using the remote sensing approaches evaluated herein, we present the first continuous timeseries of giant kelp observations in the FLK region using Landsat imagery spanning over three decades. We do not detect evidence of long-term change in the FLK region, although we observe a recent decline in total canopy area from 2017–2021. Using a nitrate model based on nearby ocean state measurements obtained from ships and incorporating satellite sea surface temperature products, we find that the area of giant kelp forests in the FLK region is positively correlated with the nitrate content observed during the prior year. Our results indicate that giant kelp classifications using citizen science are approximately consistent with classifications based on a state-of-the-art automated spectral approach. Despite differences in accuracy and sensitivity, both approaches find high interannual variability that impedes the detection of potential long-term changes in giant kelp canopy area, although recent canopy area declines are notable and should continue to be monitored carefully.This work was funded by the National Aeronautics and Space Administration as part of the Citizen Science for Earth Systems Program (https://earthdata.nasa.gov/esds/competitive-programs/csesp) with grant #80NSSC18M0103 (awarded to JEKB), which also provided salary to HFH, and by the National Science Foundation through the Santa Barbara Coastal Long-Term Environmental Research (https://sbclter.msi.ucsb.edu) program with grants #OCE 0620276 and 1232779. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Coupled impacts of the diurnal cycle of sea surface temperature on the Madden–Julian oscillation
Author Posting. © American Meteorological Society, 2014. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 27 (2014): 8422–8443, doi:10.1175/JCLI-D-14-00141.1.This study quantifies, from a systematic set of regional ocean–atmosphere coupled model simulations employing various coupling intervals, the effect of subdaily sea surface temperature (SST) variability on the onset and intensity of Madden–Julian oscillation (MJO) convection in the Indian Ocean. The primary effect of diurnal SST variation (dSST) is to raise time-mean SST and latent heat flux (LH) prior to deep convection. Diurnal SST variation also strengthens the diurnal moistening of the troposphere by collocating the diurnal peak in LH with those of SST. Both effects enhance the convection such that the total precipitation amount scales quasi-linearly with preconvection dSST and time-mean SST. A column-integrated moist static energy (MSE) budget analysis confirms the critical role of diurnal SST variability in the buildup of column MSE and the strength of MJO convection via stronger time-mean LH and diurnal moistening. Two complementary atmosphere-only simulations further elucidate the role of SST conditions in the predictive skill of MJO. The atmospheric model forced with the persistent initial SST, lacking enhanced preconvection warming and moistening, produces a weaker and delayed convection than the diurnally coupled run. The atmospheric model with prescribed daily-mean SST from the coupled run, while eliminating the delayed peak, continues to exhibit weaker convection due to the lack of strong moistening on a diurnal basis. The fact that time-evolving SST with a diurnal cycle strongly influences the onset and intensity of MJO convection is consistent with previous studies that identified an improved representation of diurnal SST as a potential source of MJO predictability.The authors gratefully acknowledge
support from the Office of Naval Research
(N00014-13-1-0133 and N00014-13-1-0139) and National
Science Foundation EaSM-3 (OCE-1419235). HS especially
thanks the Penzance Endowed Fund for their support
of Assistant Scientists at WHOI.2015-05-1
Fed up, desperate and daring enough to unionize
This is a long-form story that outlines the hazards of restaurant work that predated the pandemic, among them wage theft, racism and sexual harassment. The story focuses on three restaurant workers pushed to unionize after Covid-19 worsened working conditions by cutting take-home pay and creating new safety hazards for employees. Legislation and employer resistance are stacked against them, but for many workers organization is the only solution.
Link to Capstone: http://fedup.tilda.ws
R2: RISK FACTORS FOR SHORT-TERM DIABETES COMPLICATIONS: AN ANALYSIS OF LINKED ADMINISTRATIVE CLAIMS AND CLINICAL LABORATORY DATA
- …