4,315 research outputs found

    Multidimensional optimal droop control for DC microgrids in military applications

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    Reliability is a key consideration when microgrid technology is implemented in military applications. Droop control provides a simple option without requiring communication between microgrid components, increasing the control system reliability. However, traditional droop control does not allow the microgrid to utilize much of the power available from a solar resource. This paper applies an optimal multidimensional droop control strategy for a solar resource connected in a microgrid at a military patrol base. Simulation and hardware-in-the-loop experiments of a sample microgrid show that much more power from the solar resource can be utilized, while maintaining the system’s bus voltage around a nominal value, and still avoiding the need for communication between the various components

    Constraints on Pluto’s H and CH₄ profiles from New Horizons Alice Lyα observations

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    The Alice spectrograph on New Horizons performed several far-ultraviolet (FUV) airglow observations during the July 2015 flyby of Pluto. One of these observations, named PColor2, was a short (226 s) scan across the dayside disk of Pluto from a range of ∼34,000 km, at about 40 minutes prior to closest approach. The brightest observed FUV airglow signal at Pluto is the Lyman alpha (Lyα) emission line of atomic hydrogen, which arises primarily through the resonant scattering of solar Lyα by H atoms in the upper atmosphere, with a brightness of about 30 Rayleighs. Pluto appears dark against the much brighter (∼100 Rayleigh) sky background; this sky background is likewise the result of resonantly scattered solar Lyα, in this case by H atoms in the interplanetary medium (IPM). Here we use an updated photochemical model and a resonance line radiative transfer model to perform detailed simulations of the Lyα emissions observed in the Alice PColor2 scan. The photochemical models show that H and CH₄ abundances in Pluto’s upper atmosphere are a very strong function of the near-surface mixing ratio of CH₄, and could provide a useful way to remotely monitor seasonal climate variations in Pluto’s lower atmosphere. The morphology of the PColor2 Lyα emissions provides constraints on the current abundance profiles of H atoms and CH₄ molecules in Pluto’s atmosphere, and indicate that the globally averaged near-surface mixing ratio of CH₄ is currently close to 0.4%. This new result thus provides independent confirmation of one of the primary results from the solar occultation, also observed with the New Horizons Alice ultraviolet spectrograph

    Unraveling the mysteries of dog evolution

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    The increased battery of molecular markers, derived from comparative genomics, is aiding our understanding of the genetics of domestication. The recent BMC Biology article pertaining to the evolution of small size in dogs is an example of how such methods can be used to study the origin and diversification of the domestic dog. We are still challenged, however, to appreciate the genetic mechanisms responsible for the phenotypic diversity seen in 'our best friend'

    Constraints on Pluto’s H and CH₄ profiles from New Horizons Alice Lyα observations

    Get PDF
    The Alice spectrograph on New Horizons performed several far-ultraviolet (FUV) airglow observations during the July 2015 flyby of Pluto. One of these observations, named PColor2, was a short (226 s) scan across the dayside disk of Pluto from a range of ∼34,000 km, at about 40 minutes prior to closest approach. The brightest observed FUV airglow signal at Pluto is the Lyman alpha (Lyα) emission line of atomic hydrogen, which arises primarily through the resonant scattering of solar Lyα by H atoms in the upper atmosphere, with a brightness of about 30 Rayleighs. Pluto appears dark against the much brighter (∼100 Rayleigh) sky background; this sky background is likewise the result of resonantly scattered solar Lyα, in this case by H atoms in the interplanetary medium (IPM). Here we use an updated photochemical model and a resonance line radiative transfer model to perform detailed simulations of the Lyα emissions observed in the Alice PColor2 scan. The photochemical models show that H and CH₄ abundances in Pluto’s upper atmosphere are a very strong function of the near-surface mixing ratio of CH₄, and could provide a useful way to remotely monitor seasonal climate variations in Pluto’s lower atmosphere. The morphology of the PColor2 Lyα emissions provides constraints on the current abundance profiles of H atoms and CH₄ molecules in Pluto’s atmosphere, and indicate that the globally averaged near-surface mixing ratio of CH₄ is currently close to 0.4%. This new result thus provides independent confirmation of one of the primary results from the solar occultation, also observed with the New Horizons Alice ultraviolet spectrograph

    MARS an improved de novo peptide candidate selection method for non-canonical antigen target discovery in cancer

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    Understanding the nature and extent of non-canonical human leukocyte antigen (HLA) presentation in tumour cells is a priority for target antigen discovery for the development of next generation immunotherapies in cancer. We here employ a de novo mass spectrometric sequencing approach with a refined, MHC-centric analysis strategy to detect non-canonical MHC-associated peptides specific to cancer without any prior knowledge of the target sequence from genomic or RNA sequencing data. Our strategy integrates MHC binding rank, Average local confidence scores, and peptide Retention time prediction for improved de novo candidate Selection; culminating in the machine learning model MARS. We benchmark our model on a large synthetic peptide library dataset and reanalysis of a published dataset of high-quality non-canonical MHC-associated peptide identifications in human cancer. We achieve almost 2-fold improvement for high quality spectral assignments in comparison to de novo sequencing alone with an estimated accuracy of above 85.7% when integrated with a stepwise peptide sequence mapping strategy. Finally, we utilize MARS to detect and validate lncRNA-derived peptides in human cervical tumour resections, demonstrating its suitability to discover novel, immunogenic, non-canonical peptide sequences in primary tumour tissue

    Ultraviolet Spectroscopy of Asteroid (4) Vesta

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    We report a comprehensive review of the UV-visible spectrum and rotational lightcurve of Vesta combining new observations by Hubble Space Telescope and Swift Gamma-ray Burst Observatory with archival International Ultraviolet Explorer observations. The geometric albedos of Vesta from 220 nm to 953 nm are derived by carefully comparing these observations from various instruments at different times and observing geometries. Vesta has a rotationally averaged geometric albedo of 0.09 at 250 nm, 0.14 at 300 nm, 0.26 at 373 nm, 0.38 at 673 nm, and 0.30 at 950 nm. The linear spectral slope as measured between 240 and 320 nm in the ultraviolet displays a sharp minimum near a sub-Earth longitude of 20^{\circ}, and maximum in the eastern hemisphere. This is consistent with the longitudinal distribution of the spectral slope in the visible wavelength. The photometric uncertainty in the ultraviolet is ~20%, and in the visible wavelengths it is better than 10%. The amplitude of Vesta's rotational lightcurves is ~10% throughout the range of wavelengths we observed, but is smaller at 950 nm (~6%) near the 1-\mum band center. Contrary to earlier reports, we found no evidence for any difference between the phasing of the ultraviolet and visible/near-infrared lightcurves with respect to sub-Earth longitude. Vesta's average spectrum between 220 and 950 nm can well be described by measured reflectance spectra of fine particle howardite-like materials of basaltic achondrite meteorites. Combining this with the in-phase behavior of the ultraviolet, visible, and near-infrared lightcurves, and the spectral slopes with respect to the rotational phase, we conclude that there is no global ultraviolet/visible reversal on Vesta. Consequently, this implies a lack of global space weathering on Vesta, as previously inferred from visible-near-infrared data.Comment: 44 pages, 5 figures, 1 tabl

    Factors Predicting Late Recurrence for Estrogen Receptor-Positive Breast Cancer

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    This is a pre-copy-editing, author-produced PDF of an article accepted for publication in JNCI: Journal of the National Cancer Institute following peer review. The definitive publisher-authenticated version of 'Sestak, Ivana, et al. "Factors Predicting late recurrence for estrogen receptor–Positive Breast cancer." Journal of the National Cancer Institute (2013): djt244' is available online at: http://dx.doi.org/10.1093/jnci/djt24

    Impact of facial conformation on canine health: Brachycephalic Obstructive Airway Syndrome

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    The domestic dog may be the most morphologically diverse terrestrial mammalian species known to man; pedigree dogs are artificially selected for extreme aesthetics dictated by formal Breed Standards, and breed-related disorders linked to conformation are ubiquitous and diverse. Brachycephaly–foreshortening of the facial skeleton–is a discrete mutation that has been selected for in many popular dog breeds e.g. the Bulldog, Pug, and French Bulldog. A chronic, debilitating respiratory syndrome, whereby soft tissue blocks the airways, predominantly affects dogs with this conformation, and thus is labelled Brachycephalic Obstructive Airway Syndrome (BOAS). Despite the name of the syndrome, scientific evidence quantitatively linking brachycephaly with BOAS is lacking, but it could aid efforts to select for healthier conformations. Here we show, in (1) an exploratory study of 700 dogs of diverse breeds and conformations, and (2) a confirmatory study of 154 brachycephalic dogs, that BOAS risk increases sharply in a non-linear manner as relative muzzle length shortens. BOAS only occurred in dogs whose muzzles comprised less than half their cranial lengths. Thicker neck girths also increased BOAS risk in both populations: a risk factor for human sleep apnoea and not previously realised in dogs; and obesity was found to further increase BOAS risk. This study provides evidence that breeding for brachycephaly leads to an increased risk of BOAS in dogs, with risk increasing as the morphology becomes more exaggerated. As such, dog breeders and buyers should be aware of this risk when selecting dogs, and breeding organisations should actively discourage exaggeration of this high-risk conformation in breed standards and the show ring
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