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  • 1
    Electronic Resource
    Electronic Resource
    REPLY TO COMMENTS ON “THE RADIATION OF ACOUSTIC WAVES FROM AN AIR-GUN’ (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 26 (1978), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2478.1978.tb01606.x
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  • 2
    Electronic Resource
    Electronic Resource
    REPLY TO A. ZIOLKOWSKI'S COMMENTS (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 25 (1977), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2478.1977.tb01163.x
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  • 3
    Electronic Resource
    Electronic Resource
    ON THE MINIMIZATION OF THE DISTORTION CAUSED BY THE GEOPHONE-GROUND COUPLING (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 26 (1978), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: It is well known that the application of the “bright spot’ technique has been more successful in marine prospecting than in land prospecting. This is due partly to the problem of distortion of the seismic signal caused by the geophone-ground coupling, especially when carrying out high resolution, shallow seismic surveys in swampy terrain.The effect of geophone-ground coupling on the response of a single geophone to the incident compressional waves has been treated by several authors. However, they have always neglected the influence of mutual interaction between an array of geophones on the response of each geophone forming the array. We show that mutual interaction, which results from the re-radiation of the incident compressional waves by the geophones forming the array, can have considerable effect on the response of each geophone.The effect of the geophone-ground coupling on the response of a seismic channel is considered in the absence and presence of mutual interaction between a group of geophones for the case when the shear wave velocity of the soil varies by a factor of three.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2478.1978.tb01614.x
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  • 4
    Electronic Resource
    Electronic Resource
    THE RADIATION OF ACOUSTIC WAVES FROM AN AIR-GUN (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 24 (1976), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A theoretical model is developed for predicting three important parameters of the pressure pulse radiated by an air-gun, namely the rise time, the amplitude of the initial pulse, and the period of the bubble pulse. A knowledge of these three parameters is essential for the efficient design of air-guns arrays.The prediction of the amplitude of the initial pulse is based on the assumption that the initial pulse is radiated by a spherical source with surface area equal to that of the air-gun ports and not by a spherical source with initial volume equal to that of the air-gun chamber, as has been assumed previously.A simple equation is obtained for predicting the period of the bubble pulsation, taking into account the effect of the air-gun body, boundaries such as the sea-surface and seabed and the presence of a number of identical air-guns placed at the same depth and fired simultaneously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2478.1976.tb01571.x
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  • 5
    Electronic Resource
    Electronic Resource
    EFFICIENT DESIGN OF AIR-GUN ARRAYS (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 24 (1976), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A new technique is developed for shaping the pressure bubble pulse radiated by an array of air-guns. It involves the proper spacing of identical units. It is shown that considerable shortening of the pressure bubble pulse can be achieved provided there is sufficient mutual coupling between all the air-guns.The existing air-gun array technique for reducing the bubble pulse involves the redistribution of the energy of the bubble pulses which are produced by an array of variable sized air-guns such that no energy of the bubble pulses is radiated along the perpendicular to the array axis and only the sum of the initial pulses produced by the air-guns forming the array is radiated along that direction. However, the new air-guns array technique involves the damping of the bubble pulses which are produced by an array of identical air-guns by means of mutual interaction and the effective pressure pulse radiated by the array is given by the sum of the damped bubble pulses produced by the mutually coupled identical air-guns.Preliminary field trials gave results consistent with the theoretical predictions. A comparison between the waveforms of the pressure bubble pulses radiated by a single air-gun and by an array of four identical air-guns shows that, due to the presence of mutual coupling between the four air-guns, effective damping of the bubble pulse radiated by the array is about 50% greater than that of the bubble pulse radiated by the single air-gun.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2478.1976.tb01572.x
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  • 6
    Electronic Resource
    Electronic Resource
    CALIBRATION OF MARINE SEISMIC SOURCES USING A HYDROPHONE OF UNKNOWN SENSITIVITY (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 24 (1976), S. 0 
    Details
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: The absolute amplitude of the pressure pulse radiated by a marine seismic source is one of the prime criteria used in evaluating its performance. A technique for this measurement is proposed which is applicable to all sources which radiate a bubble pulse. The technique is described with reference to an air-gun array in which the pulse radiated from a single gun is compared with that radiated by the full array. The advantage of the method is that absolute values of pressure are obtained without any need for a calibrated hydrophone. In theory this may seem a trivial advantage but in practice sensitivity factors for the hydrophone channel cannot always be relied upon. The proposed technique is illustrated by an example.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2478.1976.tb00929.x
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  • 7
    Electronic Resource
    Electronic Resource
    Direct relationship between urinary prostaglandin E and sodium excretion in essential hypertensive patients (1976)
    Springer
    Cellular and molecular life sciences 32 (1976), S. 1280-1281 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Urinary prostaglandins (PGEs and PGFs), sodium and potassium were measured in 17 essentially hypertensive patients. Significant positive correlations were found between a) PGEs secreted in 24 h and sodium excreted in 24 h, b) the ratio PGEs/UNaV before and PGEs/UNaV after volume expansion and c) the ratio Na/K and urinary PGEs. It was suggested that renal PGEs, potent natriuretic and diuretic substances, play an important homeostatic role in the extracellular fluid regulation, and consequently in long-term control of the arterial blood pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01953093
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  • 8
    Electronic Resource
    Electronic Resource
    Deficiency in renomedullary prostaglandin synthesis related to the evolution of essential hypertension (1976)
    Springer
    Cellular and molecular life sciences 32 (1976), S. 1015-1017 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Continued PG synthesis in the early stages of essential hypertension might reflect an activation of the renal antihypertensive function in respect to neurogenic and/or hormonal pression stimuli, subsequently a deficiency of renal PG synthesis related to irreversible changes with the kidney would lead to the prepoderance of a pressure mechanism, resulting to a further increase of blood pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01933945
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  • 9
    Electronic Resource
    Electronic Resource
    Comparison of the pharmacokinetics of intravenous dl-propranolol in borderline and permanent hypertension (1976)
    Springer
    European journal of clinical pharmacology 10 (1976), S. 387-393 
    Details
    ISSN: 1432-1041
    Keywords: Pharmacokinetics ; dl-propranolol ; borderline hypertensives ; permanent hypertensives ; cardiac output
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In borderline and permanent hypertensives after rapid i.v. injection of dl-propranolol 0.2 mg/kg plasma levels were measured and were fitted to a two-compartment open-model. In borderline patients, characterized by a high basal cardiac output (CO), plasma levels were always lower than in permanent hypertensives. The biological half-life was reduced and the central volume of distribution, volume of distribution at pseudo-equilibrium and total clearance (TC) were markedly increased. In the overall population, there was a significant positive correlation between CO and TC. Rapid achievement of a predetermined plateau in each group constituted experimental proof of the validity of the two-compartment open-model for kinetic analysis of propranolol i.v. If kinetic parameters from permanent hypertensives were applied to borderline hypertensives a lower plateau was obtained. Thus, in so far as β-blockade is related to plasma level of propranolol, an increased intravenous dose may be required in patients with high CO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00563074
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of certain antiadrenergic agents on systolic time intervals in essential hypertension (1977)
    Springer
    European journal of clinical pharmacology 11 (1977), S. 423-427 
    Details
    ISSN: 1432-1041
    Keywords: Systolic time intervals ; propranolol ; clonidine ; methyldopa ; essential hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Systolic time intervals, including preejection period (PEP) and left ventricular ejecion time (LVET), were studied in patients with permanent essential hypertension before and after intra-venous administration of propranolol 0.2 mg/kg (11 patients), clonidine 0.002 mg/kg (10 patients) and methyldopa 2 mg/kg (12 patients). With propranolol, diastolic blood pressure was unchanged and the heart rate decreased, whilst PEP and LVET were significantly prolonged (P〈0.001). Clonidine caused a fall in blood pressure (P〈0.001), heart rate was slightly reduced, PEP was prolonged (P〈0.001) and there was a significant decrease in LVET at 5 min. With methyldopa, no significant effect was observed after intravenous injection, but 7 days oral administration produced the identical effect as clonidine. These observations suggest that certain antihypertensive drugs may impair left ventricular performance and depress myocardial contractility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00562932
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