1,699 research outputs found

    Borrowed alleles and convergence in serpentine adaptation

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    ACKNOWLEDGMENTS. We thank members of the L.Y. and K.B. laboratories for helpful discussions. This work was supported through the European Research Council Grant StG CA629F04E (to L.Y.); a Harvard University Milton Fund Award (to K.B.); Ruth L. Kirschstein National Research Service Award 1 F32 GM096699 from the NIH (to L.Y.); National Science Foundation Grant IOS-1146465 (to K.B.); NIH National Institute of General Medical Sciences Grant 2R01GM078536 (to D.E.S.); and Biotechnology and Biological Sciences Research Council Grant BB/L000113/1 (to D.E.S.)Peer reviewedPublisher PD

    Extended performance solar electric propulsion thrust system study. Volume 4: Thruster technology evaluation

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    Several thrust system design concepts were evaluated and compared using the specifications of the most advanced 30 cm engineering model thruster as the technology base. Emphasis was placed on relatively high power missions (60 to 100 kW) such as a Halley's comet rendezvous. The extensions in thruster performance required for the Halley's comet mission were defined and alternative thrust system concepts were designed in sufficient detail for comparing mass, efficiency, reliability, structure, and thermal characteristics. Confirmation testing and analysis of thruster and power processing components were performed, and the feasibility of satisfying extended performance requirements was verified. A baseline design was selected from the alternatives considered, and the design analysis and documentation were refined. The baseline thrust system design features modular construction, conventional power processing, and a concentrator solar array concept and is designed to interface with the Space Shuttle

    A Modeling Study on the Sensitivities of Atmospheric Charge Separation According to the Relative Diffusional Growth Rate Theory to Nonspherical Hydrometeors and Cloud Microphysics

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    Collisional charge transfer between graupel and ice crystals in the presence of cloud droplets is considered the dominant mechanism for charge separation in thunderclouds. According to the relative diffusional growth rate (RDGR) theory, the hydrometeor with the faster diffusional radius growth is charged positively in such collisions. We explore sensitivities of the RDGR theory to nonspherical hydrometeors and six parameters (pressure, temperature, liquid water content, sizes of ice crystals, graupel, and cloud droplets). Idealized simulations of a thundercloud with two‐moment cloud microphysics provide a realistic sampling of the parameter space. Nonsphericity and anisotropic diffusional growth strongly control the extent of positive graupel charging. We suggest a tuning parameter to account for anisotropic effects not represented in bulk microphysics schemes. In a susceptibility analysis that uses automated differentiation, we identify ice crystal size as most important RDGR parameter, followed by graupel size. Simulated average ice crystal size varies with temperature due to ice multiplication and heterogeneous freezing of droplets. Cloud microphysics and ice crystal size thus indirectly determine the structure of charge reversal lines in the traditional temperature‐water‐content representation. Accounting for the variability of ice crystal size and potentially habit with temperature may help to explain laboratory results and seems crucial for RDGR parameterizations in numerical models. We find that the contribution of local water vapor from evaporating rime droplets to diffusional graupel growth is only important for high effective water content. In this regime, droplet size and pressure are the dominant RDGR parameters. Otherwise, the effect of local graupel growth is masked by small ice crystal sizes that result from ice multiplication

    Radiation measurements in the new tandem accelerator FEL

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    The measurements of both spontaneous and stimulated emissions of radiation in the newly configured Israeli EA-FEL are made for the first time. The radiation at the W-band was measured and characterized. The results match the predictions of our earlier theoretical modeling and calculations.Comment: 4 pages, 3 figures, FEL 2003 Conference repor

    Method for separating single-wall carbon nanotubes and compositions thereof

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    The invention relates to a process for sorting and separating a mixture of (n, m) type single-wall carbon nanotubes according to (n, m) type. A mixture of (n, m) type single-wall carbon nanotubes is suspended such that the single-wall carbon nanotubes are individually dispersed. The nanotube suspension can be done in a surfactant-water solution and the surfactant surrounding the nanotubes keeps the nanotube isolated and from aggregating with other nanotubes. The nanotube suspension is acidified to protonate a fraction of the nanotubes. An electric field is applied and the protonated nanotubes migrate in the electric fields at different rates dependent on their (n, m) type. Fractions of nanotubes are collected at different fractionation times. The process of protonation, applying an electric field, and fractionation is repeated at increasingly higher pH to separated the (n, m) nanotube mixture into individual (n, m) nanotube fractions. The separation enables new electronic devices requiring selected (n, m) nanotube types

    The utility of MRI in predicting radiographic erosions in the metatarsophalangeal joints of the rheumatoid foot: a prospective longitudinal cohort study

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    INTRODUCTION: Magnetic resonance imaging (MRI) may reveal rheumatoid arthritis (RA) changes in the feet when hands are normal. The purpose of this study was to determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a metatarsophalangeal (MTP) erosion on MRI to predict a subsequent radiographic erosion in the same joint. Similar analyses were performed for bone marrow edema, predicting a subsequent MRI erosion. Descriptive results of other lesions are reported. METHODS: Fifty patients with RA of less than 5 years' duration who were rheumatoid factor-positive and/or anti-cyclic citrullinated peptide-positive were recruited. Patients on anti-tumor necrosis factor (TNF) therapy were excluded. Anti-TNF therapy could begin after enrollment. MRI and radiographs of the 3rd, 4th, and 5th MTP joints bilaterally were taken at baseline and at 6, 12, and 24 months. Clinical data were collected. RESULTS: Fifty patients were recruited; 46 patients had suitable data. Results for MRI erosions predicting subsequent radiographic erosions for 6, 12, and 24 months, respectively, were as follows: sensitivity 0.75, 0.60, 0.75; specificity 0.93, 0.94, 0.94; PPV 0.086, 0.10, 0.17; NPV 0.998, 0.995, 0.995. Results for MRI bone marrow edema predicting MRI erosions at 6 and 12 months, respectively, revealed sensitivity 0.50, 0.67; specificity 0.97, 0.97; PPV 0.25, 0.50; NPV 0.99, 0.99. Synovitis was the most common finding and, when present in isolation, resolved on 67.3% of subsequent studies. MRI erosions persisted on subsequent studies with one exception. Forty-six percent of the cohort was on anti-TNF therapy after study inception. CONCLUSIONS: The PPV of MRI erosions to predict subsequent radiographic erosions was low. Similarly, the PPV of bone marrow edema to predict a later MRI erosion was low. Alternatively, the NPV of the absence of an MRI erosion or bone marrow edema predicts that a later radiographic erosion or MRI erosion will likely not develop. Anti-TNF therapies may have resulted in the lower-than-anticipated PPVs. MRI descriptions of bone edema may represent a more critical time to treat in order to avoid damage, whereas an MRI erosion represents more permanent damage. This study suggests that imaging modalities more sensitive than radiographs are necessary to monitor disease in the biologic era

    What Does Weight Have to Do with It? Parent Perceptions of Weight and Pain in a Pediatric Chronic Pain Population

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    Tailored pain management strategies are urgently needed for youth with co-occurring chronic pain and obesity; however, prior to developing such strategies, we need to understand parent perspectives on weight in the context of pediatric chronic pain. Participants in this study included 233 parents of patients presenting to a multidisciplinary pediatric chronic pain clinic. Parents completed a brief survey prior to their child\u27s initial appointment; questions addressed parents\u27 perceptions of their child\u27s weight, and their perceptions of multiple aspects of the relationship between their child\u27s weight and chronic pain. The majority (64%) of parents of youth with obesity accurately rated their child\u27s weight; this group of parents was also more concerned (p \u3c 0.05) about their child\u27s weight than parents of youth with a healthy weight. However, the majority of parents of youth with obesity did not think their child\u27s weight contributed to his/her pain, or that weight was relevant to their child\u27s pain or pain treatment. Overall, only half of all parents saw discussions of weight, nutrition, and physical activity as important to treating their child\u27s pain. Results support the need for addressing parents\u27 perceptions of their child\u27s weight status, and educating parents about the relationship between excessive weight and chronic pain

    Correction to : Efficacy and Safety of Switching to Ixekizumab in Etanercept Non-Responders: A Subanalysis from Two Phase III Randomized Clinical Trials in Moderate-to-Severe Plaque Psoriasis (UNCOVER-2 and -3)

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    Altres ajuts: NCT01597245 and NCT01646177 and the post hoc analyses of these studies presented in this manuscript were funded by Eli Lilly and Company.Patients with psoriasis who have an inadequate response to one biologic may benefit from switching to a new biologic, such as ixekizumab, a high affinity monoclonal antibody that selectively targets interleukin (IL)-17A. Our aim was to assess the response to ixekizumab in patients with moderate-to-severe plaque psoriasis who did not respond adequately to etanercept using a post-hoc analysis in two phase III studies. For the subanalyses in two phase III trials (UNCOVER-2 and -3), non-response was defined by either failure to have a static physician global assessment (sPGA) of 0/1 in UNCOVER-2 or failure to have at least 75% improvement in psoriasis area and severity index (PASI 75) in UNCOVER-3 at Week 12 of each study. Non-responders treated with twice-weekly etanercept 50 mg in the first 12 weeks received two injections of placebo at Week 12 (4-week wash-out period), followed by ixekizumab every 4 weeks (Q4W) for Weeks 16-60. Non-responders to placebo in the first 12 weeks were administered ixekizumab 160 mg at Week 12, followed by ixekizumab Q4W for Weeks 16-60. After switching to ixekizumab Q4W, a substantial proportion of patients with moderate-to-severe psoriasis who did not respond to etanercept experienced rapid and durable improvement in all efficacy evaluations. Among sPGA 0/1 (UNCOVER-2) and PASI 75 (UNCOVER-3) non-responders to etanercept, 73.0% achieved sPGA 0/1 and 78.2% achieved PASI 75, respectively, after 12 weeks of ixekizumab treatment. Safety profiles in patients switched from etanercept to ixekizumab were similar to those in patients switched from placebo to ixekizumab. Patients who were non-responders to etanercept after 12 weeks, as defined by failure to meet sPGA 0/1 (UNCOVER-2) or PASI 75 (UNCOVER-3), achieved high levels of response 12 weeks after switching to ixekizumab. Studies are registered with ClinicalTrials.gov (NCT01597245 and NCT01646177)
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