471 research outputs found

    Wake Vortex Research in the USA (WakeNet-USA)

    Get PDF
    This viewgraph presentation reviews the cooperative work that FAA and NASA are engaged in to safely increase the capacity of the National Airspace System by studying the wake vortex operations. Wake vortex avoidance is a limiting factor in defining separation standards in the airport terminal area and could become a reducing separation standards in en route airspace

    Dealing with Sulfur Deficiency in Northeast Iowa Alfalfa Production

    Get PDF
    Historically, sulfur (S) deficiency has not been an issue for crop production in Iowa. Previous research documented sufficient plant available S for crop production on most soil associations (Alesii, 1982). Recent studies in corn and soybean production were consistent with results of previous research conducted across Iowa (Sawyer and Barker, 2002). The exception was a longstanding suggestion to apply S as commercial fertilizer or livestock manure for alfalfa production on sandy soils. However, over the past decade, alfalfa grown on some silt loam and loam soils in northeast Iowa has exhibited a slowly worsening problem with areas in fields of stunted growth and poor coloration. Recent investigations determined the growth problems were largely due to S deficiency. The following provides reasons for the developing problem, how to identify S deficiency, a summary of the research in northeast Iowa, and S fertilizer recommendations for alfalfa

    Comparing ASCAT and CYGNSS Winds near Tropical Convection

    Get PDF
    Gradient Features identified in ASCAT (Advanced Scatterometer) data correspond well to observed CYGNSS (Cyclone Global Navigation Satellite System) wind shifts: Comparing ASCAT and CYGNSS winds near tropical convection. Gradient wind magnitude in ASCAT observations has been recently shown to be a useful proxy for the presence of tropical convection cold pools. To help confirm this in the vicinity of precipitation we perform a comparison with the L-band CYGNSS wind dataset. Integrated Multi-satellite Retrievals for GPM (Global Precipitation Measurement)) IMERG

    The Meteorology of Storms that Produce Narrow Bipolar Events

    Get PDF
    Narrow Bipolar Event's (NBE) are compact ( 10 kW in VHF), and impulsive (approx 10 micro s) electrical discharges in thunderstorms, also known as compact intracloud discharges (CIDs). Can be either positive or negative polarity and have distinctive broadband waveform signatures sometimes confused for +CGs in the past by NLDN and other networks. NBEs are related to lightning but are likely optically "dark". As revealed by VHF sensors (both satellite and ground): (1) The most powerful lightning-related VHF sources observed (2) Tend to occur at the beginning of intracloud discharges (3) Difficult to estimate altitude properly due to receiver saturation

    Lessons from New York City’s Struggle Against Amazon HQ2 in Long Island City

    Full text link
    For three months between November 2018 and February 2019, the entire world, it seemed, was watching Long Island City, Queens. On November 12, 2018, nearly two years after Amazon announced that the company would be holding a contest for its second corporate headquarters (Amazon HQ2), New York City Mayor Bill de Blasio and New York State Governor Andrew Cuomo jointly announced that Amazon had selected Long Island City as one of its two HQ2 locations. The project, outlined in a Memorandum of Understanding (MOU) between Amazon and New York City and State, would provide up to 3billioninpublic(stateandcity)subsidiestoAmazoninexchangeforbuilding4–8millionsquarefeetofofficespaceontheEastRiverwaterfrontandcreating25,000jobsaveraging3 billion in public (state and city) subsidies to Amazon in exchange for building 4–8 million square feet of office space on the East River waterfront and creating 25,000 jobs averaging 150,000 per year (over ten years). However, fierce opposition to the plan quickly emerged. As the buzz (and controversy) concerning Amazon HQ2 continued to grow, the next two months witnessed a series of public events dedicated to the Amazon plan—including meetings, discussions, teach-ins, city council hearings, canvassing operations, Internet discussion forums, and protests. Then suddenly, on Valentine’s Day, in a tersely worded statement Amazon announced that it was no longer planning to build its second headquarters in Long Island City. The shock waves from this second surprise decision emerged immediately and continue to reverberate today. But while we may never know the true reason(s) for this decision, the struggle over the project and Amazon’s attempt to control and manage community engagement in the planning process are instructive in their own right. From the arguments that emerged both for and against the Amazon plan we can discern the contours of the emerging struggles over urban space between big tech, the state, and immigrant and working-class communities in global cities such as New York City. The Amazon experience in Long Island City also sheds light on the power of organizing across multiple issue areas in struggles against big tech’s designs on the contemporary city

    Portfolios, the Pied Piper of Teacher Certification Assessments: Legal and Psychometric Issues

    Get PDF
    Since about 90% of schools, colleges, and departments of education are currently using portfolios of one form or another as decision-making tools for standards-based decisions regarding certification or licensure (as well as NCATE accreditation), it is appropriate to explore the legal and psychometric aspects of this assessment device. The authors demonstrate that portfolios being used in a high-stakes context are technically testing devices and therefore need to meet psychometric standards of validity, reliability, fairness, and absence of bias. These standards, along with federal law, form the cornerstone for legal challenges to high-stakes decisions when students are denied a diploma or license based on the results of the assessment. The conclusion includes a list of requirements and caveats for using portfolios for graduation and certification decisions in a standards-based environment that help institutions reduce exposure to potential litigation
    • …
    corecore