520 research outputs found

    The power inversion adaptive array

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    After the brief review on adaptive array processing, three fairly separate topics on the power inversion adaptive array are treated in this thesis. The first topic is the behaviour of a narrowband array using the stochastic gradient descent algorithm, with the environment assumed to rotate at constant velocity in the sine domain. Conditions for steady state weight deviations and output power deterioration from optimal values due to the nonstationary environment are derived and are then used to determine the maximum scan rate of a radar side-lobe canceller. The second topic is the jamming rejection capability of a broadband array using tapped delay line processing. The results obtained are used for designing the tap spacing and number of taps of the delay lines as well as assessing, in terms of the number of variable weights, the relative advantage of the alternative broadband processing method using several narrowband array processors. The frequency distortions at various directions introduced by rejecting the jammers are also studied qualitatively. The third topic is the convergence behaviour of the broadband array when the stochastic gradient descent algorithm is employed. Comparison with the alternative broadband processing method is again given. A simple transformation pre-processor, independent of the external environment and capable of improving the convergence behaviour of using tapped delay line processing, is also derived

    Inspiral and Plunging Orbits in Kerr-Newman Spacetimes

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    We present the analytical solutions for the trajectories that spiral and plunge inward the event horizon along the timelike geodesics of particles following general non-equatorial paths within Kerr-Newman spacetimes. Our studies encompass both bound and unbound motions. The solutions can be written in terms of the elliptical integrals and the Jacobian elliptic functions of manifestly real functions of the Mino time, and can respectively reduce to the Kerr, Reissner-Nordstro¨\ddot{o}m, and Schwarzschild black holes in certain limits of the spin and charge of the black holes. The results can be compared with some of the known ones restricted in the equatorial plane. These explicit solutions may find applications such as the black hole accretion.Comment: 28 pages, 9 figure

    Regge Closed String Scattering and its Implication on Fixed angle Closed String Scattering

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    We calculate the complete closed string high energy scattering amplitudes (HSA) in the Regge regime for arbitrary mass levels. As an application, we deduce the complete ratios among closed string HSA in the fixed angle regime by using Stirling number identities. These results are in contrast with the incomplete set of closed string HSA in the fixed angle regime calculated previously. The complete forms of the fixed angle amplitudes, and hence the ratios, were not calculable previously without the input of zero-norm state calculation. This is mainly due to the lack of saddle point in the fixed angle closed string calculation.Comment: 10 pages. v2: typos correcte

    Butylidenephthalide antagonizes cromakalim-induced systolic pressure reduction in conscious normotensive rats

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    Merged planning photographs of [284] southern pavilion rubble fill removed to reveal ditch fill and natural; facing west; linked as external references to excavation plan 'Thwing_4-2_excavation_plan.dwg

    Biochanin A, a Phytoestrogenic Isoflavone with Selective Inhibition of Phosphodiesterase 4, Suppresses Ovalbumin-Induced Airway Hyperresponsiveness

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    The present study investigated the potential of biochanin A, a phytoestrogenic isoflavone of red clover (Triflolium pratense), for use in treating asthma or chronic obstructive pulmonary disease (COPD). Biochanin A (100 μmol/kg, orally (p.o.)) significantly attenuated airway resistance (RL), enhanced pause (Penh), and increased lung dynamic compliance (Cdyn) values induced by methacholine (MCh) in sensitized and challenged mice. It also significantly suppressed an increase in the number of total inflammatory cells, neutrophils, and eosinophils, and levels of cytokines, including interleukin (IL)-2, IL-4, IL-5, and tumor necrosis factor (TNF)-α in bronchoalveolar lavage fluid (BALF) of the mice. However, it did not influence interferon (IFN)-γ levels. Biochanin A (100 μmol/kg, p.o.) also significantly suppressed the total and ovalbumin (OVA)-specific immunoglobulin E (IgE) levels in the serum and BALF, and enhanced the total IgG2a level in the serum of these mice. The PDE4H/PDE4L value of biochanin A was calculated as >35. Biochanin A did not influence xylazine/ketamine-induced anesthesia. Biochanin A (10~30 μM) significantly reduced cumulative OVA (10~100 μg/mL)-induced contractions in the isolated guinea pig trachealis, suggesting that it inhibits degranulation of mast cells. In conclusion, red clover containing biochanin A has the potential for treating allergic asthma and COPD

    Hesperetin, a Selective Phosphodiesterase 4 Inhibitor, Effectively Suppresses Ovalbumin-Induced Airway Hyperresponsiveness without Influencing Xylazine/Ketamine-Induced Anesthesia

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    Hesperetin, a selective phosphodiesterase (PDE)4 inhibitor, is present in the traditional Chinese medicine, “Chen Pi.” Therefore, we were interested in investigating its effects on ovalbumin- (OVA-) induced airway hyperresponsiveness, and clarifying its rationale for ameliorating asthma and chronic obstructive pulmonary disease (COPD). Hesperetin was revealed to have a therapeutic (PDE4H/PDE4L) ratio of >11. Hesperetin (10 ~ 30 μmol/kg, intraperitoneally (i.p.)) dose-dependently and significantly attenuated the airway hyperresponsiveness induced by methacholine. It also significantly suppressed the increases in total inflammatory cells, macrophages, lymphocytes, neutrophils, and eosinophils, and levels of cytokines, including interleukin (IL)-2, IL-4, IL-5, interferon-γ, and tumor necrosis factor-α in bronchoalveolar lavage fluid (BALF). It dose-dependently and significantly suppressed total and OVA-specific immunoglobulin E levels in the BALF and serum. However, hesperetin did not influence xylazine/ketamine-induced anesthesia, suggesting that hesperetin has few or no emetic effects. In conclusion, the rationales for ameliorating allergic asthma and COPD by hesperetin are anti-inflammation, immunoregulation, and bronchodilation
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