174 research outputs found

    Particle-in-cell Simulations of Ion Dynamics in a Pinched-beam Diode

    Get PDF
    article-in-cell simulations of a 1.6 MV, 800 kA, and 50 ns pinched-beam diode have been completed with emphasis placed on the quality of the ion beams produced. Simulations show the formation of multiple regions in the electron beam flow characterized by locally high charge and current density (“hot spots”). As ions flow through the electron-space-charge cloud, these hot spots electrostatically attract ions to produce a non-uniform ion current distribution. The length of the cavity extending beyond the anode-to-cathode gap (i.e., behind the cathode tip) influences both the number and amplitude of hot spots. A longer cavity length increases the number of hot spots yet significantly reduces the amplitude producing a smoother, more uniform ion beam than for shorter cavities. The net current and the ion bending angles are also significantly smaller with long cavities

    Sustained Release Myofascial Release as Treatment for a Patient with Complications of Rheumatoid Arthritis and Collagenous Colitis: A Case Report

    Get PDF
    Background: Myofascial release (MFR) is a manual therapeutic technique used to release fascial restrictions, which may cause neuromusculoskeletal and systemic pathology. Purpose: This case report describes the use of sustained release MFR techniques in a patient with a primary diagnosis of rheumatoid arthritis (RA) and a secondary diagnosis of collagenous colitis. Changes in pain, cervical range of motion, fatigue, and gastrointestinal tract function, as well as the impact of RA on daily activities, were assessed. Methods: A 54-year-old white woman presented with signs and symptoms attributed to RA and collagenous colitis. Pre and post measurements were taken with each treatment and during the interim between the initial and final treatment series. The patient recorded changes in pain, fatigue, gastrointestinal tract function, and quality of life. Cervical range of motion was assessed. Six sustained release MFR treatment sessions were provided over a 2-week period. Following an 8-week interim, two more treatments were performed. Results: The patient showed improvements in pain, fatigue, gastrointestinal tract function, cervical range of motion, and quality of life following the initial treatment series of six sessions. The patient maintained positive gains for 5 weeks following the final treatment, after which her symptoms returned to near baseline measurements. Following two more treatments, positive gains were achieved once again. Conclusions: In a patient with RA and collagenous colitis, the application of sustained release MFR techniques in addition to standard medical treatment may provide short-term and long-term improvements in comorbid symptoms and overall quality of life

    Not all parents are equal for MO-CMA-ES

    Get PDF
    International audienceThe Steady State variants of the Multi-Objective Covariance Matrix Adaptation Evolution Strategy (SS-MO-CMA-ES) generate one offspring from a uniformly selected parent. Some other parental selection operators for SS-MO-CMA-ES are investigated in this paper. These operators involve the definition of multi-objective rewards, estimating the expectation of the offspring survival and its Hypervolume contribution. Two selection modes, respectively using tournament, and inspired from the Multi-Armed Bandit framework, are used on top of these rewards. Extensive experimental validation comparatively demonstrates the merits of these new selection operators on unimodal MO problems

    275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0-10

    Get PDF
    Since 2014, NASA's K2 mission has observed large portions of the ecliptic plane in search of transiting planets and has detected hundreds of planet candidates. With observations planned until at least early 2018, K2 will continue to identify more planet candidates. We present here 275 planet candidates observed during Campaigns 0-10 of the K2 mission that are orbiting stars brighter than 13 mag (in Kepler band) and for which we have obtained high-resolution spectra (R = 44,000). These candidates are analyzed using the VESPA package (Morton 2012, 2015b) in order to calculate their false-positive probabilities (FPP). We find that 149 candidates are validated with an FPP lower than 0.1%, 39 of which were previously only candidates and 56 of which were previously undetected. The processes of data reduction, candidate identification, and statistical validation are described, and the demographics of the candidates and newly validated planets are explored. We show tentative evidence of a gap in the planet radius distribution of our candidate sample. Comparing our sample to the Kepler candidate sample investigated by Fulton et al. (2017), we conclude that more planets are required to quantitatively confirm the gap with K2 candidates or validated planets. This work, in addition to increasing the population of validated K2 planets by nearly 50% and providing new targets for follow-up observations, will also serve as a framework for validating candidates from upcoming K2 campaigns and the Transiting Exoplanet Survey Satellite, expected to launch in 2018.Comment: Published in AJ, 47 pages, 18 figures, 7 tables, associated supplementary dataset available at https://zenodo.org/record/116479

    Killer whale genomes reveal a complex history of recurrent admixture and vicariance

    Get PDF
    Reconstruction of the demographic and evolutionary history of populations assuming a consensus tree‐like relationship can mask more complex scenarios, which are prevalent in nature. An emerging genomic toolset, which has been most comprehensively harnessed in the reconstruction of human evolutionary history, enables molecular ecologists to elucidate complex population histories. Killer whales have limited extrinsic barriers to dispersal and have radiated globally, and are therefore a good candidate model for the application of such tools. Here, we analyse a global data set of killer whale genomes in a rare attempt to elucidate global population structure in a nonhuman species. We identify a pattern of genetic homogenisation at lower latitudes and the greatest differentiation at high latitudes, even between currently sympatric lineages. The processes underlying the major axis of structure include high drift at the edge of species' range, likely associated with founder effects and allelic surfing during postglacial range expansion. Divergence between Antarctic and non‐Antarctic lineages is further driven by ancestry segments with up to fourfold older coalescence time than the genome‐wide average; relicts of a previous vicariance during an earlier glacial cycle. Our study further underpins that episodic gene flow is ubiquitous in natural populations, and can occur across great distances and after substantial periods of isolation between populations. Thus, understanding the evolutionary history of a species requires comprehensive geographic sampling and genome‐wide data to sample the variation in ancestry within individuals

    The genome-wide dynamics of purging during selfing in maize

    Get PDF
    Self-fertilization (also known as selfing) is an important reproductive strategy in plants and a widely applied tool for plant genetics and plant breeding. Selfing can lead to inbreeding depression by uncovering recessive deleterious variants, unless these variants are purged by selection. Here we investigated the dynamics of purging in a set of eleven maize lines that were selfed for six generations. We show that heterozygous, putatively deleterious single nucleotide polymorphisms are preferentially lost from the genome during selfing. Deleterious single nucleotide polymorphisms were lost more rapidly in regions of high recombination, presumably because recombination increases the efficacy of selection by uncoupling linked variants. Overall, heterozygosity decreased more slowly than expected, by an estimated 35% to 40% per generation instead of the expected 50%, perhaps reflecting pervasive associative overdominance. Finally, three lines exhibited marked decreases in genome size due to the purging of transposable elements. Genome loss was more likely to occur for lineages that began with larger genomes with more transposable elements and chromosomal knobs. These three lines purged an average of 398 Mb from their genomes, an amount equivalent to three Arabidopsis thaliana genomes per lineage, in only a few generations

    Oseltamivir-Resistant Pandemic A/H1N1 Virus Is as Virulent as Its Wild-Type Counterpart in Mice and Ferrets

    Get PDF
    The neuraminidase inhibitor oseltamivir is currently used for treatment of patients infected with the pandemic A/H1N1 (pH1N1) influenza virus, although drug-resistant mutants can emerge rapidly and possibly be transmitted. We describe the characteristics of a pair of oseltamivir-resistant and oseltamivir-susceptible pH1N1 clinical isolates that differed by a single change (H274Y) in the neuraminidase protein. Viral fitness of pH1N1 isolates was assessed in vitro by determining replication kinetics in MDCK α2,6 cells and in vivo by performing experimental infections of BALB/c mice and ferrets. Despite slightly reduced propagation of the mutant isolate in vitro during the first 24 h, the wild-type (WT) and mutant resistant viruses induced similar maximum weight loss in mice and ferrets with an identical pyrexic response in ferrets (AUC of 233.9 and 233.2, P = 0.5156). Similarly, comparable titers were obtained for the WT and the mutant strains on days 1, 3, 6 and 9 post-infection in mouse lungs and on days 1–7 in ferret nasal washes. A more important perivascular (day 6) and pleural (days 6 and 12) inflammation was noted in the lungs of mice infected with the H274Y mutant, which correlated with increased pulmonary levels of IL-6 and KC. Such increased levels of IL-6 were also observed in lymph nodes of ferrets infected with the mutant strain. Furthermore, the H274Y mutant strain was transmitted to ferrets. In conclusion, viral fitness of the H274Y pH1N1 isolate is not substantially altered and has the potential to induce severe disease and to disseminate
    corecore