3,702 research outputs found

    Thermoelastic analysis of solar cell arrays and their material properties

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    Announced report discusses experimental test program in which five different solar cell array designs were evaluated by subjecting them to 60 thermal cycles from minus 190 deg to 0.0 deg. Results indicate that solder-coated cells combined with Kovar n-interconnectors and p-interconnectors are more durable under thermal loading than other configurations

    Influence of analysis and design models on minimum weight design

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    The results of numerical experiments designed to illustrate how the minimum weight design, accuracy, and cost can be influenced by: (1) refinement of the finite element analysis model and associated load path problems, and (2) refinement of the design variable linking model are examined. The numerical experiments range from simple structures where the modelling decisions are relatively obvious and less costly to the more complex structures where such decisions are less obvious and more costly. All numerical experiments used employ the dual formulation in ACCESS-3 computer program. Guidelines are suggested for creating analysis and design models that predict a minimum weight structure with greater accuracy and less cost. These guidelines can be useful in an interactive optimization environment and in the design of heuristic rules for the development of knowledge-based expert optimization systems

    The Performance of the Robo-AO Laser Guide Star Adaptive Optics System at the Kitt Peak 2.1-m Telescope

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    Robo-AO is an autonomous laser guide star adaptive optics system recently commissioned at the Kitt Peak 2.1-m telescope. Now operating every clear night, Robo-AO at the 2.1-m telescope is the first dedicated adaptive optics observatory. This paper presents the imaging performance of the adaptive optics system in its first eighteen months of operations. For a median seeing value of 1.31′′1.31^{\prime\prime}, the average Strehl ratio is 4\% in the i′i^\prime band and 29\% in the J band. After post-processing, the contrast ratio under sub-arcsecond seeing for a 2≤i′≤162\leq i^{\prime} \leq 16 primary star is five and seven magnitudes at radial offsets of 0.5′′0.5^{\prime\prime} and 1.0′′1.0^{\prime\prime}, respectively. The data processing and archiving pipelines run automatically at the end of each night. The first stage of the processing pipeline shifts and adds the data using techniques alternately optimized for stars with high and low SNRs. The second "high contrast" stage of the pipeline is eponymously well suited to finding faint stellar companions.Comment: 12 pages, 16 figures, to be submitted to PAS

    FCER2 (Fc fragment of IgE, low affinity II, receptor for (CD23))

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    Review on FCER2 (Fc fragment of IgE, low affinity II, receptor for (CD23)), with data on DNA, on the protein encoded, and where the gene is implicated

    Stress corrosion in titanium alloys and other metallic materials

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    Multiple physical and chemical techniques including mass spectroscopy, atomic absorption spectroscopy, gas chromatography, electron microscopy, optical microscopy, electronic spectroscopy for chemical analysis (ESCA), infrared spectroscopy, nuclear magnetic resonance (NMR), X-ray analysis, conductivity, and isotopic labeling were used in investigating the atomic interactions between organic environments and titanium and titanium oxide surfaces. Key anhydrous environments studied included alcohols, which contain hydrogen; carbon tetrachloride, which does not contain hydrogen; and mixtures of alcohols and halocarbons. Effects of dissolved salts in alcohols were also studied. This program emphasized experiments designed to delineate the conditions necessary rather than sufficient for initiation processes and for propagation processes in Ti SCC

    Robo-AO Kepler Survey IV: the effect of nearby stars on 3857 planetary candidate systems

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    We present the overall statistical results from the Robo-AO Kepler planetary candidate survey, comprising of 3857 high-angular resolution observations of planetary candidate systems with Robo-AO, an automated laser adaptive optics system. These observations reveal previously unknown nearby stars blended with the planetary candidate host star which alter the derived planetary radii or may be the source of an astrophysical false positive transit signal. In the first three papers in the survey, we detected 440 nearby stars around 3313 planetary candidate host stars. In this paper, we present observations of 532 planetary candidate host stars, detecting 94 companions around 88 stars; 84 of these companions have not previously been observed in high-resolution. We also report 50 more-widely-separated companions near 715 targets previously observed by Robo-AO. We derive corrected planetary radius estimates for the 814 planetary candidates in systems with a detected nearby star. If planetary candidates are equally likely to orbit the primary or secondary star, the radius estimates for planetary candidates in systems with likely bound nearby stars increase by a factor of 1.54, on average. We find that 35 previously-believed rocky planet candidates are likely not rocky due to the presence of nearby stars. From the combined data sets from the complete Robo-AO KOI survey, we find that 14.5\pm0.5% of planetary candidate hosts have a nearby star with 4", while 1.2% have two nearby stars and 0.08% have three. We find that 16% of Earth-sized, 13% of Neptune-sized, 14% of Saturn-sized, and 19% of Jupiter-sized planet candidates have detected nearby stars.Comment: Accepted to the Astronomical Journa

    Effective treatment with rituximab for the maintenance of remission in frequently relapsing minimal change disease

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    AIM: Treatment of frequently relapsing or steroid-dependent minimal change disease (MCD) in children and adults remains challenging. Glucocorticoids and/or other immunosuppressive agents are the mainstay of treatment, but patients often experience toxicity from prolonged exposure and may either become treatment dependent and/or resistant. Increasing evidence suggests that rituximab (RTX) can be a useful alternative to standard immunosuppression and allow withdrawal of maintenance immunosuppressants; however, data on optimal treatment regimens, long-term efficacy and safety are still limited. METHODS: We undertook a prospective study of RTX to allow immunosuppression minimization in 15 young adults with frequently relapsing or steroid-dependent, biopsy-proven MCD. All patients were in remission at the start of treatment and on a calcineurin inhibitor. Two doses of RTX (1 gr) were given 6 months apart. A subset of patients also received an additional dose 12 months later, in order to examine the benefit of re-treatment. Biochemical and clinical parameters were monitored over an extended follow-up period of up to 43 months. RESULTS: Median steroid-free survival after RTX was 25 months (range 4-34). Mean relapse frequency decreased from 2.60 ± 0.28 to 0.4 ± 0.19 (P < 0.001) after RTX. Seven relapses occurred, five of which (71%) when CD19 counts were greater than 100 µ. Immunoglobulin levels remained unchanged, and no major side effects were observed throughout the follow-up period. CONCLUSIONS: Rituximab therapy is effective at maintaining prolonged steroid-free remission and reducing relapse frequency in this group of patients. Our study lends further support for the role of RTX in the treatment of patients with frequently relapsing or steroid-dependent MCD

    Robo-AO Kepler Survey V: The effect of physically associated stellar companions on planetary systems

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    The Kepler light curves used to detect thousands of planetary candidates are susceptible to dilution due to blending with previously unknown nearby stars. With the automated laser adaptive optics instrument, Robo-AO, we have observed 620 nearby stars around 3857 planetary candidates host stars. Many of the nearby stars, however, are not bound to the KOI. In this paper, we quantify the association probability between each KOI and detected nearby stars through several methods. Galactic stellar models and the observed stellar density are used to estimate the number and properties of unbound stars. We estimate the spectral type and distance to 145 KOIs with nearby stars using multi-band observations from Robo-AO and Keck-AO. We find most nearby stars within 1" of a Kepler planetary candidate are likely bound, in agreement with past studies. We use likely bound stars as well as the precise stellar parameters from the California Kepler Survey to search for correlations between stellar binarity and planetary properties. No significant difference between the binarity fraction of single and multiple planet systems is found, and planet hosting stars follow similar binarity trends as field stars, many of which likely host their own non-aligned planets. We find that hot Jupiters are ~4x more likely than other planets to reside in a binary star system. We correct the radius estimates of the planet candidates in characterized systems and find that for likely bound systems, the estimated planetary candidate radii will increase on average by a factor of 1.77, if either star is equally likely to host the planet. We find that the planetary radius gap is robust to the impact of dilution, and find an intriguing 95%-confidence discrepancy between the radius distribution of small planets in single and binary systems.Comment: 19 pages, 12 figures, submitted to AAS Journal
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