Echo Traces Research Articles

Echocardiography in evaluation of mitral valve prostheses.

Thirty-three patients with mitral valve prostheses were studied with echocardiography in an effort to determine if this technique could be useful in detecting significant abnormalities. Recordings were obtained in the supine position with the transducer directed to record maximum excursion of the prosthesis. Echoes from the struts, poppet and sewing ring were readily recorded. Amplitude of excursion and opening and closing velocities of the poppet were measured. Fifty echocardiographic recordings were obtained from the 33 patients. Of the 33 patients studied, 22 were thought to have "normal" echo tracings while in 11, the tracings were considered "abnormal." Apparent abnormalities consisted of: 1) abnormal diastolic separation between the poppet and strut, 2) increased echoes near the poppet, strut or sewing ring and 3) a combination of both. There was only one instance of suspected "sticking" of the prosthesis. All patients who had "abnormal" studies except one developed complications associated with their prosthesis (90%) compared to only 36% in patients with "normal" tracings. Five patients in each group died. Autopsy studies are described and correlations with the echocardiographic findings are made. In low profile valves reduction in excursion of the disc may be an indication of malfunction. Echocardiography appears to be of value in the assessment of function of mitral valve prostheses.

Radio-Echo Sounding: Glaciological Interpretations and Applications

AbstractAfter a brief review of factors relevant to the propagation of radio waves in ice, problems of profiling the upper and bedrock surfaces of ice sheets are considered. These include deconvolution of echo traces and accurate navigation. Results already available not only provide knowledge of sub-ice geomorphology, but also confirm our general ideas on interaction of temperature and flow in large ice sheets. Difficulties encountered in the study of temperate glaciers appear to be due to irregular dielectric properties of the ice mass, which in turn suggest an irregular distribution of water. In the future, application of radio-echo methods should lead to more detailed knowledge of accumulation and ablation over ice masses, improve our understanding of temperatures at great depths in polar ice sheets, and give data on ice movement from central areas of ice sheets.

Radio-Echo Sounding: Glaciological Interpretations and Applications

AbstractAfter a brief review of factors relevant to the propagation of radio waves in ice, problems of profiling the upper and bedrock surfaces of ice sheets are considered. These include deconvolution of echo traces and accurate navigation. Results already available not only provide knowledge of sub-ice geomorphology, but also confirm our general ideas on interaction of temperature and flow in large ice sheets. Difficulties encountered in the study of temperate glaciers appear to be due to irregular dielectric properties of the ice mass, which in turn suggest an irregular distribution of water. In the future, application of radio-echo methods should lead to more detailed knowledge of accumulation and ablation over ice masses, improve our understanding of temperatures at great depths in polar ice sheets, and give data on ice movement from central areas of ice sheets.

Abyssal Furrows and Hyperbolic Echo Traces on the Bahama Outer Ridge

Near-bottom investigations with a deep-towed instrument package show that steep-sided, flat-floored furrows (1 to 100 m wide by 0.5 to 20 m deep) eroded into Holocene and Pleistocene hemipelagic mud are responsible for the characteristic hyperbolic echo traces on surface-ship echograms recorded over the Bahama Outer Ridge (water depth, 4 to 5 km). This echogram character, previously interpreted as being caused by side reflections from depositional wave forms, has been typically recorded in abyssal regions of contour-current activity. It is suggested that these remarkably straight longitudinal furrows are formed by secondary helical circulations in the bottom-boundary mixed layer.

The topography of the seafloor around Orkney and Shetland and in the northern North Sea

The construction of a bathymetric map of the continental shelf of the British Isles around Orkney and Shetland and extending east to the Norwegian Trench and as farsouth as Aberdeen is described. The map is based on echo traces made by a large number of ships in the course of their duties and also on all available published charts and much unpublished bathymetric data. The map is presented together with maps showing the nature of the bottom and the roughness of the bottom based on information obtained during the construction of the bathymetric map. The origins of the various features appearing in the maps are discussed. It is shown that in the Orkney and Shetland area broad flat bottomed deeps coincide with basins of young sediments (post-Devonian and probably Mesozoic or Tertiary) and are probably of glacial origin. In the North Sea deeps are mostly very narrow and elongate and these have been interpreted as tunnel-valleys formed beneath an ice front. They are arranged in an arcuate belt partly surrounding the deepest part of the North Sea where there is a patch of mud. This mud was probably deposited from the water flowing out from beneath the ice where it was formed into a lake. It is possible that a submarine canyon on the edge of the Norwegian Trench to the east of the mud patch is the overflow channel for this water.

Fish echoes on a long-range sonar display

The display of research echo-ranging equipment bottom-laid in shallow water has shown many echo traces. Returns from fish shoals and from areas of bottom roughness have both been seen out to ranges of a few tens of kilometres. The fish tracks or “wrigglers” are more common in the summer, show a tidal motion, and usually disappear at night when the shoals disband. Although many different types of pattern have been seen, it is possible to estimate that the typical shoal is 10–15 m across with about 3 × 104 pilchard in it. The work is useful in fish behaviour, geological and oceanographic studies.

サケ・マス魚探技術の若干の問題点について-III

This paper presents results of experiments on the practical use of the horizontal fish finder in the salmon fishing grounds in the North Pacific Ocean. The tests were made in July, 1968. On the ship we mounted two fish finders, each of which had a transducer with a 50 KHz supersonic. We kept these transducers 1 meter deep. The dip angles of the transducers were changed with the state of the sea. These echo patterns were made on the occasion of the voyage of the research ship “WAKASHIO MARU” (153 tons) for fishery investigations. Recordings by the fish finder were made as long as possible while the ship was floating by the set-nets. One of the characteristics of the echo patterns of the horizontal fish finder was that the echo of sawtooth recorded on the paper was cleared away almost completely. Because of the use of T. V. G circuit a relation was found between wind direction and the transducers. The echo patterns of the horizontal fish finder given showed salmon echoes quite clearly. We set salmon gillnets of 55 tans and hauled the nets the next morning. Considering the catches of salmon, we found that the catch of salmon was in proportion to the numbers of echo traces of salmon on the patterns.

Ultrasonic evaluation of prosthetic valve motion.

1. Ultrasound echo tracing is a simple, atraumatic method for examining prosthetic valve function. 2. In vitro experiments have elucidated the meaning of traces obtained from various types of caged balls. 3. By the use of this method ball diameter, poppet excursion, and opening and closing velocities can be measured in patients. 4. Both in vitro and in vivo experience has demonstrated that the measurements obtained are accurate and reproducible.

Conjugate echoes in Alouette-2 topside-sounder data

Three types of ionograms containing symmetric conjugate echo traces which appear frequently in the Alouette-2 satellite topside-sounder data are presented and explained in terms of multiple reflections between conjugate points of the field line passing through the satellite. Such symmetric traces have not been previously reported in the literature. The high intensity of these traces gives credence to the existence of magnetospheric waveguides along which signals can propagate with very little attenuation.

Ionospheric Electron‐Density Profiles With Continuous Gradients and Underlying Ionization Corrections. III. Practical Procedures and Some Instructive Examples

A description is given of procedures developed at the Institute for Telecommunication Sciences and Aeronomy (ITSA) to permit accurate extraction of virtual‐height data from ionograms in a form easily usable by digital computers. Criteria are described for identification of the significant interval limits along ionogram echo traces.

Quiet and disturbed structure and variations of the nighttimeEregion

The maximum electron concentration of the nighttime E layer, the valley above it, and the appearance of the intermediate layer are described in detail from analyses of the low-frequency ionograms (50–2000 khz) obtained at Boulder for three nights of quiet, moderate, and severe geomagnetic activity. Electron concentration profiles are obtained from the ionograms by a method giving some information about the width and depth of valley minimums in the nighttime E region. These parameters are obtained by analysis of parts of the ordinary and extraordinary radio echo traces, and then cross-checked by a ray-tracing process from which the complete ordinary and extraordinary ray curves (including the extraordinary ray below the gyrofrequency) are calculated for comparison. The profiles consistently show a deep, wide valley on magnetically quiet nights, and are filled in with increasing ionization as magnetic disturbance becomes more severe. An intermediate layer develops during strong disturbances. The latitude variation of nocturnal ionization in the intermediate region is shown. Possible causes of the nighttime E layer are discussed in connection with the results obtained.

Further evidence of contour currents in the Western North Atlantic

A study of compass-oriented sea-floor photographs, echograms and sediment cores on the Atlantic continental margin of North America has been made in order to evaluate the role of deep-sea contour currents in the shaping of the continental rise. The sediments on the upper continental rise consist of lutites which are being deposited on the sea floor in an environment devoid of strong bottom currents. Below an abrupt change in regional slope, that marks the boundary between the upper and lower continental rise, a swift bottom current is observed which flows to the southwest parallel to the contours. Beneath this current the surface sediments are distinctly coarser grained and long cores show many quartz silt laminations in the sedimentary column. Further downslope on the lower continental rise the currents are variable in direction and weaker. Measurements of northerly directions indicate that at certain locations the Gulf Stream may intermittently scour the sea floor. In the area of the Lower Continental Rise Hill a swift southwesterly current is again observed. Hyperbolic echo traces on echograms, prolonged multiple echo sequences, and wedging of sub-bottom reflecting interfaces can be mapped as distinct zones. These zones of sea floor micromorphology parallel the regional contours of the continental rise, and are produced by erosional and depositional processes of bottom currents. We conclude that the continental rise is a large sediment wedge which owes its shape to deep geostrophic contour currents.

Topside Refractive Irregularities and Travelling Ionospheric Disturbances

Munro (1950) deduced from ground-based observations that traveling ionospheric disturbances (T.LD.'s) are large-scale distortions of the electron density contours, which travel through the ionosphere, and Calvert and Schmid (1964) attributed extra traces and distortions of the main echo traces, which occur near the critical frequency of topside ionograms, to refractive effects associated with large-scale irregularities. In an examination of topside and sub-peak ionograms recorded close in position and time, it was found that on a number of occasions refractive effects occurred on topside ionograms, when manifestations of T.LD.'s were observed on sub-peak ionograms (Dyson 1967b).

Obliquez-mode echoes in the topside ionosphere

On the topside sounder records an echo trace is observed that lies between the plasma and upper hybrid frequencies and is not predicted for vertical propagation. It is shown by numerical ray tracing that these are z-mode echoes by oblique propagation between the satellite and the ordinary (X = 1) reflection level.

The Diurnal Variations in Depth and Quantity of Echo Traces and their Distribution in Area in the Southern Bight of the North Sea

The Diurnal Variations in Depth and Quantity of Echo Traces and their Distribution in Area in the Southern Bight of the North Sea

Coastal and submarine features around the Shetland islands

For some time Shetland has been recognised as an area of recent submergence. A detailed examination of the coastline reveals that in sheltered places, especially in drowned valleys, the drowning was so recent that there was insufficient time for the peat to be eroded. On exposed coasts there are many cliffs which can be explained only as a consequence of long-continued retreat. However, these cliffs have no wave-cut platforms at their feet. A study of echo traces and very detailed charts shows that the sea floor dips relatively steeply away from the feet of these cliffs in a smooth concave upward slope, and in many places the sea floor flattens out only at a depth of forty fathoms or more. This smooth slope is interpreted as a wave-cut surface formed by cliff retreat during a continuously rising sea-level. On exposed coasts the cliffs retreated continuously in front of the advancing sea, leaving the inclined wave-cut surface as the sea floor, while in sheltered drowned valleys the sea rose up the hillsides with few erosive effects. The wave-cut surface is interrupted in places by shelves which in places have an uneven topography but always dip much more gently seaward than the wave-cut surface. The most prominent shelf is at about forty-five fathoms below the present sea-level. Other features described include two landlocked deeps, the Firth and the St. Magnus deep, which were formed by glacial overdeepening. A north-south submarine valley with its bottom at about eighty fathoms lies some ten miles east of Shetland.

The Effect of Tidal Streams on the Presence of an Extensive Layer of Midwater Echo Traces

The Effect of Tidal Streams on the Presence of an Extensive Layer of Midwater Echo Traces

魚群探知機による魚群構造の調査-I

By use of fish finder (24 kc) carried by the Toko-maru, the inspection vessel of the Fishery Agency, trial observations of hair-tail shoal were done at the central part of the East China Sea on February 19th and 20th, 1959. The admissible conclusions derived from these resear-ches are reported as follows. 1) Each shoal restored from echo traces formed an ellipse in shape, about 4 to 5.5 miles along the transverse axis and 3 to 4 miles along the conjugate one, with its depth measuring 10 meters or so. 2) In the observed area covering about 170 square miles, more than three masses of fish were found to be arranged in succession from east to west or northwest, the distance between centers of such neighbouring masses beeing about 5 miles. 3) Hair-tail of this area distributed along sea bottom from after the sun-rise till sometime before the sun-set, while swam in middle layer of water by night. 4) The volume of fish contained in a single mass described above was estimated at about 1, 550 tons, being about 11, 000 times of the catch taken by 1 mile hauling through such mass.

Underwater television and research in marine biology, bottom topography and geology

1. A discussion of the general performance of the underwater television equipment previously described is given; electronically and mechanically it has been satisfactory; certain minor modifications are noted, some proposed changes are given. 2. An estimation of sizes and numbers of organisms can be made; the greatest difficulty is the estimation of numbers per unit volume of free-living organisms and this has been attempted by counting the animals in a depth of focus, arbitrary and subjectively determined. 3. The advantages and disadvantages of the method both in relation to conventional methods and with respect to remotely controlled underwater camera work are discussed. 4. An account of some observations in various types of problems is given. These include: a. The observation of bottom fauna: Estimation of population density, numbers and distribution; observations on animal behaviour. Attention is drawn to the problem of recognition. b. Problems of an experimental nature: The behaviour of animals towards traps and bait. c. Problems of bottom topography and geology: Examination of the nature of superficial bottom deposits and surface markings such as ripple marks and animal tracks. d. The observation of instruments: The apparatus may find some use in specialised problems and possibly for determining the behaviour of new equipment. e. Plankton: A rather different set up is described. Experiments on the estimation of the numbers of some larger planktonic organisms are described. f. Fish studies: The difficulties of examining fish are stressed; an account of work in which recognition by television was used in a series of echo-surveys is given. Some fish were recognised when the apparatus was lowered into a well marked echo trace and their numbers and sizes were estimated. A vertical view, although making recognition by standard features more difficult, was found best. Success depends upon the behaviour of the fish.