2,554 research outputs found

    A Kosloff/Basal method, 3D migration program implemented on the CYBER 205 supercomputer

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    Conventional finite difference migration has relied on approximations to the acoustic wave equation which allow energy to propagate only downwards. Although generally reliable, such approaches usually do not yield an accurate migration for geological structures with strong lateral velocity variations or with steeply dipping reflectors. An earlier study by D. Kosloff and E. Baysal (Migration with the Full Acoustic Wave Equation) examined an alternative approach based on the full acoustic wave equation. The 2D, Fourier type algorithm which was developed was tested by Kosloff and Baysal against synthetic data and against physical model data. The results indicated that such a scheme gives accurate migration for complicated structures. This paper describes the development and testing of a vectorized, 3D migration program for the CYBER 205 using the Kosloff/Baysal method. The program can accept as many as 65,536 zero offset (stacked) traces

    Flight determined lift and drag characteristics of an F-8 airplane modified with a supercritical wing with comparison to wind-tunnel results

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    Flight measurements obtained with a TF-8A airplane modified with a supercritical wing are presented for altitudes from 7.6 kilometers (25,000 feet) to 13.7 kilometers (45,000 feet), Mach numbers from 0.6 to 1.2, and Reynolds numbers from 0.8 x 10 to the 7th power to 2.3 x 10 to the 7th power. Flight results for the airplane with and without area-rule fuselage fairings are compared. The techniques used to determine the lift and drag characteristics of the airplane are discussed. Flight data are compared with wind-tunnel model results, where applicable

    A two-dimensional model of the quasi biennial oscillation of ozone

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    The largest amplitudes of the observed Quasi Biennial Oscillation (QBO) in column ozone are found in high latitudes and this must be taken into account in any explanation of the increased depletion of ozone in the southern polar spring during the 1980's. A QBO in zonal wind, temperature and column ozone has been successfully modelled in a two-dimensional dynamical/chemical model by the introduction of a parameterization scheme to model the transfer of momentum to the zonal flow associated with the damping of vertically propagating Kelvin and Rossby-Gravity waves. The largest anomalies in column ozone of approximately 20 DU are present at high latitudes. The equatorial ozone QBO is out of phase with the mid- and high-latitude ozone QBO, in good agreement with observations

    Trumpetcreeper response to selected herbicides

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    Field studies were conducted to; (1) attempt trumpetcreeper [Campsis radicans (L.) Seem.] control with preemergence and foliar postemergence herbicides labelled for use in no-till soybeans [Glycine max (L.) Merr.], (2) determine the effect of repeated paraquat (1,1\u27-dimethyl-4,4\u27-bipyridinium ion) applications and, (3) attempt trumpetcreeper control in non-cropped areas. Trumpetcreeper was not controlled by preemergence herbicides labelled for use in soybeans. Foliar postemergence herbicides were applied when trumpetcreeper shoots were approximately 1 meter long. Glyphosate [N-(phosphonomethyl)glycine] gave the most complete control of trumpetcreeper of the postemergence herbicides labelled for use in soybeans. Acifluorfen [5-(2-chloro-4-(trifluoromethyl)phenoxy)-2- nitrobenzoic acid], and dinoseb (2-sec-butyl-4,6-dinitrophenol) alone or in combination with naptalam ([N-1-naphthylphthalamic acid) or alachlor [2-chloro-2\u27 ,6\u27-diethyl-N-(methoxymethyl)acetanilide], gave initial trumpetcreeper control, but regrowth occurred quickly. Repeated paraquat applications did not control trumpetcreeper. Regrowth occurred when paraquat was applied at 4 or 2 week intervals; however, total shoot necrosis was observed after the third treatment, regardless of the application interval. Applications at 2 week intervals prevented the formation of leaves. Repeated paraquat applications did not appear to reduce trumpet creeper stands the season following applications. Several herbicides were evaluated for trumpetcreeper control in non-cropped areas. Dicamba (3,6-dichloro-o-anisic acid), 2,4-D [(2,4-dichlorophenoxy)acetic acid], glyphosate, SC-0224 (chemistry not released), 2,4,5-T[(2,4,5-trichlorophenoxy)acetic acid], and XRM-4660 (chemistry not released) gave near complete control during the season of application. Dicamba, fosamine [ethyl hydrogen (aminocarbonyl)phosphonate],glyphosate, and SC-0224 gave near complete control the season following applications with no regrowth

    The Effect of Adding Small Percentages of Finely Ground Metals to Enamels

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    The object of this thesis was an attempt to prevent the formation of pin holes in the process of enamelling on steel

    Cardiac Tamponade During Catheterization of a Dog with Congenital Heart Disease

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    Perforation of the heart, which was confirmed by contrast radiography, occurred during venous cardiac catheterization of a dog. As tamponade developed within the next hour, changing physical signs (progressive muffling of heart sounds and murmur, disappearance of a precordial thrill, fall in blood pressure, and increase in heart rate with a weakening pulse) indicated the need for surgical relief in spite of insignificant fluoroscopic evidence. Treatment by thoracotomy, pericardiotomy, and blood replacement was successful. Evidence of a bidirectional ventricular septal defect and probable pulmonic stenosis was observed in angiocardiograms made an hour after the thoracotomy. The dog was discharged in good condition 12 days later. Examination 3 months later revealed no after effects of the cardiac catheterization and thoracotomy

    Increasing β-catenin/Wnt3A activity levels drive mechanical strain-induced cell cycle progression through mitosis.

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    Mechanical force and Wnt signaling activate β-catenin-mediated transcription to promote proliferation and tissue expansion. However, it is unknown whether mechanical force and Wnt signaling act independently or synergize to activate β-catenin signaling and cell division. We show that mechanical strain induced Src-dependent phosphorylation of Y654 β-catenin and increased β-catenin-mediated transcription in mammalian MDCK epithelial cells. Under these conditions, cells accumulated in S/G2 (independent of DNA damage) but did not divide. Activating β-catenin through Casein Kinase I inhibition or Wnt3A addition increased β-catenin-mediated transcription and strain-induced accumulation of cells in S/G2. Significantly, only the combination of mechanical strain and Wnt/β-catenin activation triggered cells in S/G2 to divide. These results indicate that strain-induced Src phosphorylation of β-catenin and Wnt-dependent β-catenin stabilization synergize to increase β-catenin-mediated transcription to levels required for mitosis. Thus, local Wnt signaling may fine-tune the effects of global mechanical strain to restrict cell divisions during tissue development and homeostasis
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