2,860 research outputs found

    Process for preparing phthalocyanine polymer from imide containing bisphthalonitrile

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    Imide-linked bisphthalonitrile compounds are prepared by combining a dicyano aromatic diamine and an organic dianhydride to produce an amic acid linked bisphthalonitrile compound. The amic acid linked bisphthalonitrile compound is dehydrocyclized to produce the imide-linked bisphthalonitrile compounds. The imide-linked bisphthalonitrile compounds may be polymerized to produce a phythalocyanine polymer by heating the imide-linked bisphthalonitrile compound, either alone or in the presence of a metal powder or a metal salt. These compounds are useful in the coating, laminating and molding arts. The polymers are useful in composite matrix resins where increased fire resistance, toughness and resistance to moisture are required, particularly as secondary structures in aircraft and spacecraft

    Understanding life together: A brief history of collaboration in biology

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    AbstractThe history of science shows a shift from single-investigator ‘little science’ to increasingly large, expensive, multinational, interdisciplinary and interdependent ‘big science’. In physics and allied fields this shift has been well documented, but the rise of collaboration in the life sciences and its effect on scientific work and knowledge has received little attention. Research in biology exhibits different historical trajectories and organisation of collaboration in field and laboratory – differences still visible in contemporary collaborations such as the Census of Marine Life and the Human Genome Project. We employ these case studies as strategic exemplars, supplemented with existing research on collaboration in biology, to expose the different motives, organisational forms and social dynamics underpinning contemporary large-scale collaborations in biology and their relations to historical patterns of collaboration in the life sciences. We find the interaction between research subject, research approach as well as research organisation influencing collaboration patterns and the work of scientists

    Signal Processing for the Multistate Myoelectric Channel

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    In the Multistate Myoelectric Channel, a Single Myoelectric Signal Source is Used to Control a Multifunction Powered Prosthesis. the Selection of a Prosthesis Auction Requires a Receiver to Process the Myoelectric Signal, Contaminated with Noise, and to Decide on the Basis of the Received Signal Which Function is Desired. Thus, the Channel Dearly Presents a Problem of Choice of Receiver and of Decision Strategy. Previous Solutions to This Problem Have Been Basically Empirical. in This Paper We Seek the Optimum Receiver Where Optimum is in the Minimum Probability of Error Sense. First a Model is Developed for the Bipolar Myoelectric Signal to Provide Information About the Relevant Signal Parameters and Statistics. using This Information, the Bayes Mini-Mum Probability of Error Receiver is Derived for an Arbitrary Signal Parameter Set. the Optimum Signal Parameter Set is Then Found for the Bayes Receiver, and the Receiver Performance Calculated. the Receiver Performance is Measured and Compared with the Calculated Performance. a Significant Performance Improvement is Seen in the Optimum Receiver over a More Conventional Receiver. Copyright © 1977 by the Institute of Electrical and Electronics Engineers, Inc

    Photometry of Kuiper belt object (486958) Arrokoth from New Horizons LORRI

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    On January 1st 2019, the New Horizons spacecraft flew by the classical Kuiper belt object (486958) Arrokoth (provisionally designated 2014 MU69), possibly the most primitive object ever explored by a spacecraft. The I/F of Arrokoth is analyzed and fit with a photometric function that is a linear combination of the Lommel-Seeliger (lunar) and Lambert photometric functions. Arrokoth has a geometric albedo of p_v = 0.21_(−0.04)^(+0.05) at a wavelength of 550 nm and ≈0.24 at 610 nm. Arrokoth's geometric albedo is greater than the median but consistent with a distribution of cold classical Kuiper belt objects whose geometric albedos were determined by fitting a thermal model to radiometric observations. Thus, Arrokoth's geometric albedo adds to the orbital and spectral evidence that it is a cold classical Kuiper belt object. Maps of the normal reflectance and hemispherical albedo of Arrokoth are presented. The normal reflectance of Arrokoth's surface varies with location, ranging from ≈0.10–0.40 at 610 nm with an approximately Gaussian distribution. Both Arrokoth's extrema dark and extrema bright surfaces are correlated to topographic depressions. Arrokoth has a bilobate shape and the two lobes have similar normal reflectance distributions: both are approximately Gaussian, peak at ≈0.25 at 610 nm, and range from ≈0.10–0.40, which is consistent with co-formation and co-evolution of the two lobes. The hemispherical albedo of Arrokoth varies substantially with both incidence angle and location, the average hemispherical albedo at 610 nm is 0.063 ± 0.015. The Bond albedo of Arrokoth at 610 nm is 0.062 ± 0.015
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