Search

Christian Doppler, an Austrian physicist, described in 1842 the apparent change in frequency of a wave when motion of the source or the observer is involved. Named after him, this change in observational frequencies is known as the Doppler Effect. The formula for calculating the frequency change is taught in universities, textbooks, Youtube, and on the internet. Understanding the Doppler effect is used in applications such as radar. Yet, the formula is wrong, yielding a different result when applying the same velocity, once to the source, then to the observer. This article will show the formula, the error, the correction to the formula, and how it disproves Einstein’s theories of special and general relativity.

While mechanics was developed under the idea of reciprocal action (interactions), electromagnetism, as we know it today, takes a form more akin to unilateral action. Interactions call for spatial relations, unilateral action calls for space, just one reference centre. In contrast, interactions are matters of relations that require at least two centres. The development of the relational electromagnetism encouraged by Gauss appears to stop around 1870 for reasons that are not completely clear but are certainly not solely scientific. By the same time, Maxwell recognised the equivalence in formulae of his electromagnetism and the one advocated by Gauss and called for an explanation of why such theories so differently conceived have such a large part in common. In this work we reconstruct and update the relational electromagnetism up to the contributions of Lorentz guided by the non-arbitrariness principle (NAP) that requests arbitrary choices to be accompanied by groups of symmetries. We show that a-priori there must be two more symmetries in electromagnetism, one related to the breaking (in the description) of the relation source/detector and one relating all the perceptions of the same source by detectors moving with different (constant) relative velocities. We show that the idea of electromagnetic waves put forward in concept by Lorenz (1861-1863) before Maxwell (1865) and in formulae (1867) just after Maxwell, together with the ``least action principle'' proposed by Lorentz are enough to derive Maxwell's equations, the continuity equation and the Lorentz' force, and that there is a dual formulation in terms of fields of the receiver (as opposed to fields of the source). While Galilean transformations are associated with removing the arbitrariness implied in the election of a reference space, they will not explicitly appear in a formulation based upon a relational space although we occasionally mention their usefulness. In contrast, Lorentz' transformations will emerge in this formulation involving the relations between the perceived fields of different receivers. Moreover, the role of the full Poincaré-Lorentz group as a group of transformations of the perceived actions is elucidated. In summary, we answer Maxwell's philosophical question showing how the same theory in formulae can be abduced using different inferred entities. Each form of abduction implies as well an interpretation and a facilitation of the theoretical construction. This work relies heavily on logical concepts as abduction put forward by C. Peirce, needed for the construction of theories.

Copyright of Summa, Animali da Compagnia is the property of Point Veterinaire Italie s.r.l. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During the last few years, technological improvements in Doppler sonography have transformed a primitive imaging technique in a sophisticated diagnostic tool. The complexity of the physical concept which is at the basis of technique, the different ways to use it and the results depending on either the equipment quality or the operator's skill, have produced confusion and doubts about the real value of Doppler sonography for assessing diseases of the kidney and urinary tract in infants and children. The purpose of this article is to review the basic concepts concerning the physics of Doppler effect, to describe the principal Doppler sonography instrumentation (continuous-wave, pulsed-wave, color Doppler and power Doppler equipment) and to discuss the diagnostic applications of renal Doppler in paediatric imaging.

The use of color-Doppler US equipment allows the clinician to evaluate, at the same time and within the same image, both shape and structure of the examined organs and the flow patterns in the vessels within them. Such information as direction and velocity of blood flow are displayed with a variety of intravascular colors, according to a conventional code. Moreover, this diagnostic method can provide physiological and anatomical pieces of information in the same image and is therefore widely used in medical imaging. However, the images obtained by means of color-Doppler units are not always easy to understand and diagnostic misinterpretations may occur. In this paper we will summarize the physical and technological principles on which such units are based. In the first half of paper, the problems relative to acquisition and construction of the images are presented, together with the different technical approaches used to obtain flow velocity information. Moreover, the relationships between the "black-and-white" and the "color" parts of the images are described. The principles according to which color is assigned to vessels are reported, together with the patterns exhibited by a vessel according to the type of transducer used to examine it. The non-linear correlation between the color scale and flow velocities is also discussed. The second half of the paper deals with technical parameters of color-Doppler scanning, discussing the criteria of choice of transducers, the determination of Doppler angle, the setting of both wall filters and scanning depth. The problem of pulse repetition frequency (PRF) setting is also addressed; this parameter is especially critical in color-Doppler studies. The authors believe that careful setting of all examination parameters and the good knowledge of the physical and technological factors underlying color-Doppler images are the basis for a correct and useful approach to this fascinating technique.

It is well known that artifacts can be observed during US examinations; the same is true also for Doppler and color-Doppler images of blood flow. Recognizing these artifacts is important to avoid image misinterpretations and, when possible, to overcome them by modifying either techniques or unit settings, or both. This work was aimed at presenting the several artifacts which can be observed during Doppler investigations, at classifying them, and trying to understand the physical and/or technical principles underlying their origin. Doppler and color-Doppler artifacts can be divided into four large groups: 1) artifacts regarding evaluation of the presence of flow; 2) artifacts regarding evaluation of the direction of flow; 3) artifacts regarding determination of the velocity of flow; 4) artifacts affecting spatial location, on the screen, of the examined vessel. Each of the above can cause severe diagnostic misinterpretations, if not correctly recognized and interpreted. It must be kept in mind that an accurate analysis of unit settings during scanning, and the meticulous evaluation of the obtained color images are of the utmost importance for the proper use of this valuable but difficult diagnostic technique.

The Authors evaluate the Doppler ultrasonic detection in the assessment of lower limbs arterial occlusive disease, particularly concerning the haemodynamic pattern of those patients undergoing a surgical treatment. The research is accomplished on a group consisting in hundred not selected patients, all subjected to aortography. A comparative study was undertaken between angiographic findings and ankle sistolic pressure measurement together with flow velocity profile. Reduction of ankle sistolic pressure and appearance of flow velocity profile changes, resulted highly correlated with clinical stage and angiographic alterations. The Authors consider therefore the Doppler ultrasound assessment as being able to give, together with the always necessary angiographic study, more accurate informations either on the run-off and the haemodynamic consequences of a stenosis, or on the overall evaluation of multisegmental lesions.

The Authors present 38 cases of surgical revascularization for arteriosclerosis obliterans of the lower extremities, operated in Clinica Chirurgica of Ancona during the space of three Years, from 1974-1977. The morphological profile of the sphygmic wave and pressures of occlusion or Travis Winsor's index were studied pre and postoperatively with Doppler ultrasonic flowmeter. The patency of vascular grafts and after thromboendarterectomy was shown by T.W.'s index. With this method, besides establishing a program for postoperative arteriography, a lesser use of the latter was shown.

Two patients with an atypical and particularly troubled history, due to numerous direct and indirect interventions of vascular surgery, have been monitored in haemodynamic investigation using only Doppler velocimetry. The use of angiography would have necessitated other general anaesthesiae which would have further compromised the already critical conditions of the patients. Doppler velocimetry proved suitable for surgical indication in emergency situations. The value of an arteriograph under general anaesthesia is, however, unquestionable in cases of choice surgery.

The present study offers the possibility of individuating the genesis of innocent murmurs. 30 patients between 5 and 20 years, showing at the phonocardiogram a train of oscillations in a proto-mesosistolic or mesosistolic phase with characteristics that testify an innocent murmur, have been examined. The routine examinations and cardiac cateterism to exclude congenital or acquired heart diseases have been done to all the patients. The echocardiographic examination has shown a characteristic floating of the interventricular septum, that, producing a variable mutability of the dimensions of the right ventricular cavities, determines, particularly in the tract of the right ventriculae efflux, a hematic turbolent flow well visible with the Doppler effect. The genesis of the innocent murmurs must be referred to such a turbolence, secondary to the floating of the septum, and this accords with Feruglio, who asserts he has always found, with the endocavitary phonocardiography, innocent murmurs only in the infundibulum of the pulmonary.

Ten patients, 3 males and 7 females, aging less then 50 years (M: 37), suffering from at least one year for a Raynaud's phenomenon surely not due to a costo-clavicular syndrome, were studied. A Doppler ultrasound evaluation was first done recording the pressure and the speed at the omeral, radial, ulnar, and digital arteries. The patients were then submitted to an angiography in general anaesthesia through puncture of the omeral artery and to screening tests to detect possible associated immunopathological diseases. In the patients affected by Raynaud's phenomenon the vascular lesions are generally distal to the omeral artery; the only surgical indication is a thoracic gangliectomy. Our experience shows that the Doppler velocimetry gives all the data necessary to check the efficacy of a pharmacological treatment and to state a correct surgical indication.

Doppler echocardiography has been applied in a study of the tricuspid and central venous blood velocity curves in a number of cases, including eleven cases of insufficiency, six cases of stenosis, five cases of steno-insufficiency of the tricuspid valve and one case of Ebstein's disease. The tracings were compared to normal reports and to those appartaining to a few patients with right ventricular failure from different causes. For six patients the venous blood velocity curve was recorded contemporaneously with the right atrioventricular pressure curves. Doppler echocardiography has proved that it can offer useful indications on tricuspid anomalies. The analysis of the central venous and tricuspid blood velocity curve allows us to detect hemodynamic alterations characteristic of this valvular disease.

The AA. studied 96 subjects: 74 normals, 15 patients with pulmonary stenosis, 6 with pulmonary regurgitation and 1 with combined stenosis and pulmonary regurgitation, by using pulsed Doppler echocardiography. This technique, which supplements M-mode echocardiography with Doppler flow detection, allowed determination of direction and quality--laminar or turbolent--of flow through pulmonary valve. In our experience, pulsed Doppler echocardiography is a sensitive and specific method for detection of pulmonary stenosis and regurgitation and extends ultrasound diagnosis beyond the capabilities of M-mode echocardiography.

The authors have executed an investigation on the functional evaluation of the valvular prosthesis, availing themselves of the use of the Echocardiography complete of Doppler effect and executing echocardiography tracings not according to the standard position, but putting the sound in correspondence with the cardiac apex. This method has been considered valid to obtain olways images of the movable element for all the types of the prosthesis and for amy situation of theirs. Furthermore the classic position of the sound can't be respected either for the eventual cardiomegaly, either for the manipulations that the heart undergoes inevitable during the operation, either for the pleurapericardic adhesions, alla factors that induce a change of the anatomic focuses.