158 research outputs found

    Technical and Regulatory Factors of Adopting Electric Training Aircraft in a Collegiate Aviation Setting

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    Electric-powered aircraft have entered the market. The arrival of the Pipistrel Velis Electro and other developmental efforts by companies such as Bye Aerospace, Piper, and eViation, have signaled to the aviation community that more electric-powered aircraft can be expected in the coming years. But how useful are they for training pilots in a Federal Aviation Administration (FAA) approved Part 141 collegiate aviation environment? To identify candidate flight courses and lessons, the authors examine flight hour distributions of a one-year window of invoiced flights (N = 52,728), including flight hour data cut-points at 60 minutes (n = 6,050) and 90 minutes (n = 25,439). The data distribution suggests that approximately 11.5% of the candidate flights would fall within a 60-minute expected flight duration, whereas 48% of flights would fall within a 90-minute flight duration. These calculations provide realistic targets for designed minimum flight duration (plus the inclusion of required FAA reserve) in order to be determined a feasible trainer in many high-volume FAA Part 141 training environments. Detailed course-level analysis suggests the Instrument Flight Instructor (CFII) flight course as a potential launch point for electric flight due to the relatively lower flight hour per lesson. In addition to minimum flight duration, other feasibility questions are included in this analysis, such as regulatory requirements, battery duration, aircraft turnaround time, multiple charge-discharge cycles per day, environmental factors, airport charging infrastructure, and maintenance factors. Additional research will benefit this developing area of electric aircraft in flight training environments

    Sodium Atoms in the Lunar Exotail: Observed Velocity and Spatial Distributions

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    The lunar sodium tail extends long distances due to radiation pressure on sodium atoms in the lunar exosphere. Our earlier observations measured the average radial velocity of sodium atoms moving down the lunar tail beyond Earth (i.e., near the anti-lunar point) to be ~ 12.5 km/s. Here we use the Wisconsin H-alpha Mapper to obtain the first kinematically resolved maps of the intensity and velocity distribution of this emission over a 15 x 15 deg region on the sky near the anti-lunar point. We present both spatially and spectrally resolved observations obtained over four nights bracketing new Moon in October 2007. The spatial distribution of the sodium atoms is elongated along the ecliptic with the location of the peak intensity drifting 3 deg east along the ecliptic per night. Preliminary modeling results suggest the spatial and velocity distributions in the sodium exotail are sensitive to the near surface lunar sodium velocity distribution. Future observations of this sort along with detailed modeling offer new opportunities to describe the time history of lunar surface sputtering over several days

    The role of stress coping strategies for life impairments in ADHD

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    Attention-deficit/hyperactivity disorder (ADHD) is commonly accompanied by functional impairments within personal, professional, and social context as well as further psychological distress. The role of perceived stress has been examined in this regard, although little is known about the influence of stress coping strategies. We examined the dynamics between ADHD symptomatology, stress coping strategies, and life impairments in a sample of 230 clinical and non-clinical adult individuals. ADHD was associated with low probability of choosing adaptive but high probability of implementing maladaptive stress coping strategies as well as with increased life impairments. Adaptive stress coping showed little effects beyond the associations between ADHD and life impairments, whereas some maladaptive coping strategies increased current life impairments over and above the effects of ADHD and further psychological distress. The present findings emphasize the need of professional support in adults with ADHD and the necessity to include stress coping strategies in respective treatment approaches aimed at reducing life impairments

    Selection for Resistance to a Glyphosate-Containing Herbicide in Salmonella enterica Does Not Result in a Sustained Activation of the Tolerance Response or Increased Cross-Tolerance and Cross-Resistance to Clinically Important Antibiotics

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    Evolution of bacterial tolerance to antimicrobials precedes evolution of resistance and may result in cross-tolerance, cross-resistance, or collateral sensitivity to other antibiotics. Transient exposure of gut bacteria to glyphosate, the world’s most widely used herbicide, has been linked to the activation of the stress response and changes in susceptibility to antibiotics. In this study, we investigated whether chronic exposure to a glyphosate-based herbicide (GBH) results in resistance, a constitutive activation of the tolerance and stress responses, and cross-tolerance or cross-resistance to antibiotics. Of the 10 farm animal-derived clinical isolates of Salmonella enterica subjected to experimental evolution in increasing concentrations of GBH, three isolates showed stable resistance with mutations associated with the glyphosate target gene aroA and no fitness costs. Global quantitative proteomics analysis demonstrated activation of the cellular tolerance and stress response during the transient exposure to GBH but not constitutively in the resistant mutants. Resistant mutants displayed no cross-resistance or cross-tolerance to antibiotics. These results suggest that while transient exposure to GBH triggers cellular tolerance response in Salmonella enterica, this response does not become genetically fixed after selection for resistance to GBH and does not result in increased cross-tolerance or cross-resistance to clinically important antibiotics under our experimental conditions

    Retrospective Analysis of Bacterial Cultures Sampled in German Chicken- Fattening Farms During the Years 2011–2012 Revealed Additional VIM-1 Carbapenemase-Producing Escherichia coli and a Serologically Rough Salmonella enterica Serovar Infantis

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    Carbapenems are last-resort antibiotics used in human medicine. The increased detection of carbapenem-resistant Enterobacteriaceae (CRE) is therefore worrying. In 2011 we reported the first livestock-associated VIM-1-producing Salmonella (S.) enterica serovar Infantis (R3) isolate from dust, sampled in a German chicken fattening farm. Due to this observation we retrospectively investigated more than 536 stored bacterial cultures, isolated from 45 chicken fattening farms during the years 2011 and 2012. After a non-selective overnight incubation, the bacteria were transferred to selective media. Escherichia (E.) coli and Salmonella growing on these media were further investigated, including antibiotic susceptibility testing, carbapenemase gene screening and whole genome sequencing (WGS). In total, four CRE were found in three out of 45 investigated farms: Besides R3, one additional Salmonella (G-336-1a) as well as two E. coli isolates (G-336-2, G-268-2). All but G-268-2 harbored the blaVIM-1 gene. Salmonella isolates R3 and G-336-1 were closely related although derived from two different farms. All three blaVIM-1-encoding isolates possessed identical plasmids and the blaVIM-1- containing transposon showed mobility at least in vitro. In isolate G-268-2, the AmpC beta-lactamase gene blaCMY-2 but no known carbapenemase gene was identified. However, a transfer of the phenotypic resistance was possible. Furthermore, G-268-2 contained the mcr-1 gene, combining phenotypical carbapenem- as well as colistin resistance in one isolate. Carbapenem-resistant Enterobacteriaceae have been found in three out of 45 investigated chicken flocks. This finding is alarming and emphasizes the importance of intervention strategies to contain the environmental spread of resistant bacteria in animals and humans

    Hyperspectral optical absorption closure experiment in complex coastal waters

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    Accurate measurements of absorption data are required for the development and validation of inversion algorithms for upcoming hyperspectral ocean color imaging sensors, such as the NASA Phytoplankton, Aerosol, Cloud, and ocean Ecosystem mission. This study aims to provide uncertainty estimates associated with leading approaches to measure hyperspectral absorption coefficients in complex coastal waters. Absorption spectra were collected at 12 different stations, all located in the Indian River Lagoon, Florida, USA, between 09 January 2017 and 13 January 2017. Measurements included spectral absorption coefficients in the visible range (400–700 nm) associated with dissolved, a CDOM, total particulate, a p, and total nonwater, a nw, fractions, and were made both in situ and from discrete samples. Discrete sample approaches included dual-beam spectrophotometer, liquid waveguide capillary cell, point-source integrating cavity absorption meter (PSICAM) for dissolved matter absorption samples, and quantitative filter technique ICAM measurements and the dual-beam spectrophotometer with center-mounted integrating sphere filter pad technique, while the Turner Designs ICAM, and WET Labs AC-s, and AC-9 instruments were used to determine absorption coefficients in situ. The Gershun approach, determining absorption from measurement of the irradiance quartet with respect to depth was also assessed in situ. Measurement uncertainties and relative accuracies were quantified for each of these approaches. Results showed generally strong agreements between different discrete sample methods, with average percent absolute error %δ abs < 7% for a CDOM and < 9% for a p. In situ approaches showed higher variability and reduced accuracy. For a nw, %δ abs deviation relative to PSICAM data was on average 12% to 20%. Results help identify remaining technological gaps and need for improvements in the different absorption measurement approaches

    “A very orderly retreat”: Democratic transition in East Germany, 1989-90

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    East Germany's 1989-90 democratisation is among the best known of East European transitions, but does not lend itself to comparative analysis, due to the singular way in which political reform and democratic consolidation were subsumed by Germany's unification process. Yet aspects of East Germany's democratisation have proved amenable to comparative approaches. This article reviews the comparative literature that refers to East Germany, and finds a schism between those who designate East Germany's transition “regime collapse” and others who contend that it exemplifies “transition through extrication”. It inquires into the merits of each position and finds in favour of the latter. Drawing on primary and secondary literature, as well as archival and interview sources, it portrays a communist elite that was, to a large extent, prepared to adapt to changing circumstances and capable of learning from “reference states” such as Poland. Although East Germany was the Soviet state in which the positions of existing elites were most threatened by democratic transition, here too a surprising number succeeded in maintaining their position while filing across the bridge to market society. A concluding section outlines the alchemy through which their bureaucratic power was transmuted into property and influence in the “new Germany”

    An Overview of Approaches and Challenges for Retrieving Marine Inherent Optical Properties from Ocean Color Remote Sensing

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    Ocean color measured from satellites provides daily global, synoptic views of spectral water-leaving reflectances that can be used to generate estimates of marine inherent optical properties (IOPs). These reflectances, namely the ratio of spectral upwelled radiances to spectral downwelled irradiances, describe the light exiting a water mass that defines its color. IOPs are the spectral absorption and scattering characteristics of ocean water and its dissolved and particulate constituents. Because of their dependence on the concentration and composition of marine constituents, IOPs can be used to describe the contents of the upper ocean mixed layer. This information is critical to further our scientific understanding of biogeochemical oceanic processes, such as organic carbon production and export, phytoplankton dynamics, and responses to climatic disturbances. Given their importance, the international ocean color community has invested significant effort in improving the quality of satellite-derived IOP products, both regionally and globally. Recognizing the current influx of data products into the community and the need to improve current algorithms in anticipation of new satellite instruments (e.g., the global, hyperspectral spectroradiometer of the NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission), we present a synopsis of the current state of the art in the retrieval of these core optical properties. Contemporary approaches for obtaining IOPs from satellite ocean color are reviewed and, for clarity, separated based their inversion methodology or the type of IOPs sought. Summaries of known uncertainties associated with each approach are provided, as well as common performance metrics used to evaluate them. We discuss current knowledge gaps and make recommendations for future investment for upcoming missions whose instrument characteristics diverge sufficiently from heritage and existing sensors to warrant reassessing current approaches

    Rethinking Sustainability to Meet the Climate Change Challenge

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    A group of environmental law professors formed the Environmental Law Collaborative with the goal of engaging environmental law scholars in the thorny issues of the day. The members of the Collaborative gathered in the summer of 2012 to produce an intensive and collective assessment of sustainability in the age of climate change. Their writings examine the process of adapting the principles and application of sustainability to the demands of climate change, including framing the term sustainability in climate change discussions; coordinating sustainable practices across disciplines such as law, economics, ethics, and the hard sciences; and conceptualizing the role of sustainability in formulating adaptation and resiliency strategies. Their work also contemplates the role of law and legal systems in crafting effective climate change adaptation strategies and considers feasible strategies in the context of specific examples
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