78 research outputs found

    Distributed microprocessors in a tactical universal modem

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    The distributed microprocessor system associated with a wideband signal conversion unit (WBSCU) is described. Multiple embedded 8086 and 2901 microprocessors, supported by dedicated hardware modules, perform the required real time operations for both transmit and receive functions. Commands from a host computer determine the configuration of the WBSCU via the IEEE 488 bus. Each of the four WBSCU channels is assigned to process a specified IF waveform; each channel configures its own resources and, in some cases, borrows resources from other channels. The processed waveform data is communicated from individual channels to redundant global memories. Data flow between the user community and global memories occurs via redundant 1553 buses through intelligent Bus Interface Units. Each WBSCU channel contains one 2901 bit slice machine and one 8086 microprocessor. The 2901 provides high speed processing capability for the most time critical operations. The 8086 is used for lower speed processing tasks where its high level language capability can be better exploited. Each 8086 has a global bus for wideband interprocessor communication, and a local bus for 8086/2901, master/slave communication. Software architecture consists of a control and communications structure governing mode dependent signal processing tasks

    A Synthesis of Some α, γ, δ, &ksi;-Tettaketones Polyoxo Compounds. IV

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    A description is given of the preparation of the tetraketones Ia-f, which were characterized as quinoxaHne derivatives

    Age-Related Skeletal Muscle Atrophy in Humans: An Immunohistochemical and Morphometric Study

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    The aim of this study was to determine age-related changes in three human muscles with different function and location in the body. The cross sectional area and the percentage of fibers type I, type IIA and type IIX were studied in vastus lateralis, deltoideus and external intercostal muscle. Muscle samples were obtained from 30 male subjects, aged 20–80 years. Fiber types were defined immunohistochemically, using monoclonal antibodies specific for type I, type IIA and type IIX fibers. Cross sectional area of muscle fibers was analyzed morphometrically by computerized image analysis. All muscle fiber types (I, IIA, IIX) showed the reduction in the fiber size in all three examined muscles. In all muscles the proportion of type I and type IIA was changed, but not in type IIX. With increasing age results showed the increase in proportion of type I, while proportion of type IIA fibers decreased, with vastus lateralis muscle being the most affected. These results suggest that age-related muscle atrophy is not a general phenomenon, and does not affect all muscles equally

    Application of Consensus Scoring and Principal Component Analysis for Virtual Screening against β-Secretase (BACE-1)

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    BACKGROUND: In order to identify novel chemical classes of β-secretase (BACE-1) inhibitors, an alternative scoring protocol, Principal Component Analysis (PCA), was proposed to summarize most of the information from the original scoring functions and re-rank the results from the virtual screening against BACE-1. METHOD: Given a training set (50 BACE-1 inhibitors and 9950 inactive diverse compounds), three rank-based virtual screening methods, individual scoring, conventional consensus scoring and PCA, were judged by the hit number in the top 1% of the ranked list. The docking poses were generated by Surflex, five scoring functions (Surflex_Score, D_Score, G_Score, ChemScore, and PMF_Score) were used for pose extraction. For each pose group, twelve scoring functions (Surflex_Score, D_Score, G_Score, ChemScore, PMF_Score, LigScore1, LigScore2, PLP1, PLP2, jain, Ludi_1, and Ludi_2) were used for the pose rank. For a test set, 113,228 chemical compounds (Sigma-Aldrich® corporate chemical directory) were docked by Surflex, then ranked by the same three ranking methods motioned above to select the potential active compounds for experimental test. RESULTS: For the training set, the PCA approach yielded consistently superior rankings compared to conventional consensus scoring and single scoring. For the test set, the top 20 compounds according to conventional consensus scoring were experimentally tested, no inhibitor was found. Then, we relied on PCA scoring protocol to test another different top 20 compounds and two low micromolar inhibitors (S450588 and 276065) were emerged through the BACE-1 fluorescence resonance energy transfer (FRET) assay. CONCLUSION: The PCA method extends the conventional consensus scoring in a quantitative statistical manner and would appear to have considerable potential for chemical screening applications

    A cross-terms geometry based method for components instantaneous frequency estimation using the Cross Wigner-Ville distribution

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    A novel method for the signal components instantaneous frequency (IF) estimation based on the CrossWigner-Ville distribution (XWVD) is presented. The cross-terms in the XWVD are deliberately formed between the analyzed signal and a reference signal. The proposed method yields a scaled and time shifted image that closely resembles the instantaneous frequency laws of the components present in the signal. As the interferences location follow geometrical rules, and by using a reference signal well localized in time and frequency, the time-frequency coordinates of the analyzed signal components IF can be calculated by an automatic procedure described below. The performance of the method is tested on both synthetic and real-life signals, showing improvements over another recently proposed components extraction method.Scopu

    1H-N. M. R. study of the syn! anti ratio of oximes and 2,4- dinitrophenyl hydrazones determined by ASIS and LIS methods

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    Starting from 1-chloro-butane-2-one (I) and 3-chloro-butane- 2-one (II), oximes Illa, b and IV as well as 2,4-dinitrophenyl hydrazones Va, b and VI were prepared. 'H-nmr spectra show that I gives a mixture of isomeric oximes Illa and IIIb (21 : 79) and 2,4-dinitrophenyl hydrazones Va and Vb (20 : 80). From ketone II only anti isomers IV and VI were obtained. Signals were assigned using ASIS method. From paramagnetic shifts obtained by LIS method it was concluded that unshared pair of nitrogen electrons participates in complex formation with rare earth atom
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