Experiments upon the heart of the dog with reference to the maximum volume of blood sent out by the left ventricle in a single beat, and the influence of variations in venous pressure, arterial pressure, and pulse rate upon the work done by the heart

1883 ◽  
Vol 35 (224-226) ◽  
pp. 271-274
Keyword(s):  
Left Ventricle ◽  
Axillary Artery ◽  
Venous Pressure ◽  
The Body ◽  
Whole Body ◽  
Average Weight ◽  
Mean Velocity ◽  
The Subject ◽  
The Mean ◽  
Work Done

Owing to the indirectness of the methods hitherto used for estimating the quantity of blood pumped out from the left ventricle at each systole, this important factor in all calculations of the work done by the heart has never been satisfactorily determined. Of the later physiologists who have investigated the subject, Volkmann and afterwards Vierordt, from calculations based upon the mean velocity of the stream of blood in the unbranched aorta, obtained the fraction 1/100 as representing the ratio of the average weight of blood ejected at each systole of the left ventricle to the weight of the whole body. Fick, from data obtained by placing the arm in a plethysmograph, and estimating the velocity of the stream of blood in the axillary artery from the increase in volume of the whole arm at each systole of the heart, arrived at a much smaller fraction, about 1/1000 for the ratio between the weight of blood thrown out at each systole and the body weight.

scholarly journals VI. Experiments upon the heart of the dog with reference to the maximum volume of blood sent out by the left ventricle in a single beat and the influence of variations in venous pressure, arterial pressure, and pulse-rate upon the work done by the heart

1884 ◽  
Vol 175 ◽  
pp. 139-160 ◽  
Keyword(s):  
Venous Pressure ◽  
Uncertain Data ◽  
Mean Velocity ◽  
Long Time ◽  
Cause Of Failure ◽  
The Mean ◽  
The Right ◽  
The University ◽  
Short Time ◽  
Work Done

The most important factor to be determined before calculating the work done by the heart is the quantity of blood forced from the ventricles at each systole. Most of the efforts to determine this quantity have been based either upon faulty observations upon the dead heart, or upon the uncertain data obtained by estimating the mean velocity of the stream of blood in the aorta. Professor Martin accordingly suggested to us that we should attempt to measure it directly on the isolated Dog’s heart. The work thus undertaken was carried on during the greater part of the university session, 1881-82, and the results obtained are given in the following pages. The method of isolating the heart was essentially that described in Professor Martin’s paper (Phil. Trans., 1883, p. 663). In the course of this work many unexpected difficulties arose, necessitating changes in the apparatus and the method of operating, and preventing us for a long time from obtaining any successful results. In our experiments it was necessary not only that the heart should live and beat, but that it should be in the best possible physiological condition, and any marked pulmonary œdema made an experiment nearly valueless. This most frequent cause of failure was mainly owing to the fact that, on account of the large quantity of blood required for an experiment, we were obliged to use Calf’s blood obtained from the butcher; very often this blood, as Professor Martin states in his paper, will bring about œdema of the lungs in a short time; large quantities of exuded serum pour out of the tracheal cannula, the air-passages in the lungs become choked up with liquid, and the circulation from the right to the left side of the heart is greatly impeded. We have succeeded, however, in making a considerable number of experiments in which all the conditions were favourable, the œdema of the lungs not occurring to any marked extent until after many observations had been made.

scholarly journals A Multi-Channel Uncertainty-Aware Multi-Resolution Network for MR to CT Synthesis

2021 ◽  
Vol 11 (4) ◽  
pp. 1667
Author(s):  
Kerstin Klaser ◽  
Pedro Borges ◽  
Richard Shaw ◽  
Marta Ranzini ◽  
Marc Modat ◽  
...  
Keyword(s):  
Medical Image Analysis ◽  
Absolute Error ◽  
Magnetic Resonance Images ◽  
The Body ◽  
Whole Body ◽  
Image Size ◽  
Body Images ◽  
Image Translation ◽  
The Mean ◽  
Synthetic Ct

Synthesising computed tomography (CT) images from magnetic resonance images (MRI) plays an important role in the field of medical image analysis, both for quantification and diagnostic purposes. Convolutional neural networks (CNNs) have achieved state-of-the-art results in image-to-image translation for brain applications. However, synthesising whole-body images remains largely uncharted territory, involving many challenges, including large image size and limited field of view, complex spatial context, and anatomical differences between images acquired at different times. We propose the use of an uncertainty-aware multi-channel multi-resolution 3D cascade network specifically aiming for whole-body MR to CT synthesis. The Mean Absolute Error on the synthetic CT generated with the MultiResunc network (73.90 HU) is compared to multiple baseline CNNs like 3D U-Net (92.89 HU), HighRes3DNet (89.05 HU) and deep boosted regression (77.58 HU) and shows superior synthesis performance. We ultimately exploit the extrapolation properties of the MultiRes networks on sub-regions of the body.

scholarly journals Mechanotendography in Achillodynia shows reduced oscillation variability of pre-loaded Achilles tendon: a pilot study

2020 ◽  
Vol 30 (2) ◽  
pp. 247-257
Author(s):  
Laura Schaefer ◽  
Frank Bittmann
Keyword(s):  
Achilles Tendon ◽  
Rank Correlation ◽  
Achilles Tendinopathy ◽  
The Body ◽  
Mechanical Pressure ◽  
Mechanical Oscillations ◽  
Pressure Impact ◽  
The Subject ◽  
The Mean ◽  
Intrapersonal Variability

The present study focuses on an innovative approach in measuring the mechanical oscillations of pre-loaded Achilles tendon by using Mechanotendography (MTG) during application of a short yet powerful mechanical pressure impact. This was applied on the forefoot from the plantar side in direction of dorsiflexion, while the subject stood on the ball of the forefoot on one leg. Participants with Achilles tendinopathy (AT; n = 10) were compared to healthy controls (Con; n = 10). Five trials were performed on each side of the body. For evaluation, two intervals after the impulse began (0-100ms; 30-100ms) were cut from the MTG and pressure raw signals. The intrapersonal variability between the five trials in both intervals were evaluated using the arithmetic mean and coefficient of variation of the mean correlation (Spearman rank correlation) and the normalized averaged mean distances, respectively. The AT-group showed a significantly reduced variability in MTG compared to the Con-group (from p = 0.006 to p = 0.028 for different parameters). The 95% confidence intervals (CI) of MTG results were disjoint, whereas the 95% CIs of the pressure signals were similar (p = 0.192 to p = 0.601). We suggest from this work that the variability of mechanical tendon oscillations could be an indicative parameter of an altered Achilles tendon functionality.

scholarly journals Structural Organization of the Optic Lobe of Grey Breasted Helmeted Guinea Fowl (*Numida meleagris galeata*) at Pre-Hatch Study

2016 ◽  
Vol 7 (2) ◽  
pp. 26
Author(s):  
Wanmi Nathaniel ◽  
Onyeanusi I. Barth ◽  
Nzalak J. Oliver ◽  
Aluwong Tanang
Keyword(s):  
Body Weight ◽  
Structural Organization ◽  
Optic Lobe ◽  
Guinea Fowl ◽  
The Body ◽  
Whole Body ◽  
Steady Increase ◽  
Numida Meleagris ◽  
The Mean ◽  
Immature Cells

<p class="jbls-body"><span lang="EN-GB">A total of one hundred and seventy-three fertilized eggs were used for morphometry, gross and histological studies. At day 4 of incubation, the mean body weight of the helmeted guinea fowl embryo was 0.6401 ± 0.0211 g. It was at day 10 of incubation that there was an increase in the whole body weight of the embryo to be 0.8650 ± 0.676 g. The whole brain weight indicated relative increased at day 4 as compared to that of the whole body weight. Graphically, there were steady increase in the body, brain and optic lobe weights. Histologically, cells and neurones that make up the optic lobe is probably as a result of the migration of immature cells from the ventricular neuroepithelium. </span></p>

Measurements of Mean Velocity and Turbulent Statistics in a Centrifugal Blood Pump

2002 ◽  
Author(s):  
Steven W. Day ◽  
James C. McDaniel ◽  
Phillip P. Lemire ◽  
Houston G. Wood
Keyword(s):  
Blood Flow ◽  
Left Ventricle ◽  
Heart Transplantation ◽  
Mechanical Design ◽  
Left Ventricular ◽  
The Body ◽  
Western World ◽  
Mean Velocity ◽  
Centrifugal Blood Pump ◽  
Turbulent Statistics

An estimated 150,000 patients in the Western World require heart transplantation every year, while only 4,000 (2.5%) of them actually receive a donor heart [1]. This lack of available donors for heart transplantation has led to a large effort since the 1960s to develop an artificial mechanical heart as an alternative to heart transplant. Most end stage cardiac failures result from cardiac disease or tissue damage of the left ventricle. After this failure, the ventricle is not strong enough to deliver an adequate supply of oxygen to critical organs. A left ventricular assist device (LVAD) is a mechanical pump that does not replace the native heart, but rather works in concert with it. An LVAD can effectively relieve some strain from a native heart, which has been weakened by disease or damage, and increase blood flow supplied to the body to maintain normal physiologic function. The inlet to the LVAD is attached to the native left ventricle, and the output of the assist pump rejoins the output of the native heart at the aorta, as shown in Figure 1. Blood flow from both the aortic valve and the assist pump combine and flow through the body. The clinical effectiveness of LVADs has been demonstrated; however, all of the currently available pumps have a limited life because of either the damage that they cause to blood or their limited mechanical design life.

scholarly journals Morphometry of indian roofed turtle, Pangshura tecta (Gray 1831) in Bangladesh

2015 ◽  
Vol 41 (2) ◽  
pp. 207-215
Author(s):  
Md Lokman Hossain ◽  
Shorab Uddin Sarker ◽  
Noor Jahan Sarker
Keyword(s):  
Body Weight ◽  
Adult Male ◽  
The Body ◽  
Morphometric Study ◽  
Average Weight ◽  
The Mean

Morphometric study was conducted on Indian roofed turtle, Pangshura tecta, between January 1997 and December 2000 in several district of Bangladesh. The mean weight of adult male was 92.6 ± 13.3 g and of female 441.1 ± 185.4 g. The length and width of carapace as well as those of the plastron and the height of the shell varied with the body weight of the turtle. The percentage of hard parts of the body weight of P. tecta was 35.8 ± 2.5 %, whereas percentage of soft parts of the body weight was 64.2 ± 2.5 %. The average weight of the female P. tecta was 4.8 times higher than that of the male.Bangladesh J. Zool. 41(2): 207-215, 2013

XXI. The direct influence of gradual variations of temperature upon the rate of beat of the dog’s heart

1883 ◽  
Vol 174 ◽  
pp. 663-688 ◽  
Keyword(s):  
Arterial Pressure ◽  
Pulse Rate ◽  
Venous Pressure ◽  
Practical Importance ◽  
The Body ◽  
Full Account ◽  
Heart Beating ◽  
External Conditions ◽  
Work Done ◽  
Made In

In the year 1881 I briefly described (1) a method of experimenting by which the heart and lungs of a Dog or Cat could be completely isolated physiologically from the remainder of the body of the animal, and kept alive some hours for study in an apparently normal condition, the heart beating regularly and maintaining a good arterial pressure. Since then I have been at work investigating the influence of various conditions upon the pulse-rate of Dogs’ hearts so isolated; while under my supervision several of my pupils have been engaged in studying the work done in a unit of time by such hearts under different external conditions. As regards the effects of variations of arterial pressure upon the pulse-rate of the isolated Dog’s heart, my results have already been published (2); and detailed observations as to the influence of variations in venous pressure will shortly be printed. But in so far as the influence of temperature variations upon the cardiac rhythm is concerned, only a brief preliminary announcement (3) has been made. In the present paper I propose to give a full account of my experiments upon this subject, which is one that, apart from and in addition to its purely physiological interest, has considerable practical importance in connexion with inquiries as to the immediate cause of the quick pulse so constantly found in warm-blooded animals suffering from fever.

Axisymmetric laminar wake behind a slender body of revolution

1976 ◽  
Vol 76 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Francis R. Hama ◽  
Leigh F. Peterson
Keyword(s):  
Experimental Information ◽  
The Body ◽  
Body Of Revolution ◽  
Empirical Theory ◽  
Mean Velocity ◽  
Laminar Wake ◽  
Flow Field Characteristics ◽  
The Mean ◽  
Semi Empirical ◽  
Slender Body Of Revolution

At the body-diameter Reynolds number 2000, the axisymmetric wake behind a slender streamlined body of revolution remained laminar without any indication of breakup far beyond the five-body-lengths test section. The mean-velocity profiles were measured with close spacings in order to obtain experimental information on the transient process from boundary layer to fully developed wake. A semi-empirical theory was developed to describe the flow-field characteristics.

Wakes behind two-dimensional surface obstacles in turbulent boundary layers

1974 ◽  
Vol 64 (3) ◽  
pp. 529-564 ◽  
Author(s):  
J. Counihan ◽  
J. C. R. Hunt ◽  
P. S. Jackson
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Turbulent Boundary Layer ◽  
The Body ◽  
Wake Flow ◽  
Two Dimensional ◽  
Mean Velocity ◽  
Velocity Deficit ◽  
Wind Tunnel Measurements ◽  
The Mean

By making simple assumptions, an analytical theory is deduced for the mean velocity behind a two-dimensional obstacle (of heighth) placed on a rigid plane over which flows a turbulent boundary layer (of thickness δ). It is assumed thath[Gt ] δ, and that the wake can be divided into three regions. The velocity deficit −uis greatest in the two regions in which the change in shear stress is important, a wall region (W) close to the wall and a mixing region (M) spreading from the top of the obstacle. Above these is the external region (E) in which the velocity field is an inviscid perturbation on the incident boundary-layer velocity, which is taken to have a power-law profileU(y) =U∞(y−y1)n/δn, wheren[Gt ] 1. In (M), assuming that an eddy viscosity (=KhU(h)) can be defined for the perturbed flow in terms of the incident boundary-layer flow and that the velocity is self-preserving, it is found thatu(x,y) has the form$\frac{u}{U(h)} = \frac{ C }{Kh^2U^2(h)} \frac{f(n)}{x/h},\;\;\;\; {\rm where}\;\;\;\; \eta = (y/h)/[Kx/h]^{1/(n+2)}$, and the constant which defines the strength of the wake is$C = \int^\infty_0 y^U(y)(u-u_E)dy$, whereu=uE(x, y) asy→ 0 in region (E).In region (W),u(y) is proportional to Iny.By considering a large control surface enclosing the obstacle it is shown that the constant of the wake flow is not simply related to the drag of the obstacle, but is equal to the sum of the couple on the obstacle and an integral of the pressure field on the surface near the body.New wind-tunnel measurements of mean and turbulent velocities and Reynolds stresses in the wake behind a two-dimensional rectangular block on a roughened surface are presented. The turbulent boundary layer is artificially developed by well-established methods (Counihan 1969) in such a way that δ = 8h. These measurements are compared with the theory, with other wind-tunnel measurements and also with full-scale measurements of the wind behind windbreaks.It is found that the theory describes the distribution of mean velocity reasonably well, in particular the (x/h)−1decay law is well confirmed. The theory gives the correct self-preserving form for the distribution of Reynolds stress and the maximum increase of the mean-square turbulent velocity is found to decay downstream approximately as$ (\frac{x}{h})^{- \frac{3}{2}} $in accordance with the theory. The theory also suggests that the velocity deficit is affected by the roughness of the terrain (as measured by the roughness lengthy0) in proportion to In (h/y0), and there seems to be some experimental support for this hypothesis.

Mobility of Normal Observers under Conditions of Reduced Visual Input

Perception ◽  
1992 ◽  
Vol 21 (6) ◽  
pp. 813-823 ◽  
Author(s):  
Margo Eyeson-Annan ◽  
Brian Brown
Keyword(s):  
Visual Information ◽  
Motion Parallax ◽  
Reference Points ◽  
Local Motion ◽  
Mean Velocity ◽  
Light Emitting ◽  
Mobility Performance ◽  
Darkened Room ◽  
The Subject ◽  
The Mean

The importance in mobility performance of the rate of presentation of visual information, binocular versus monocular vision, the use of multiple rather than single reference points, and local motion parallax was investigated in two experiments. In each experiment ten subjects walked a triangular mobility course in a totally darkened room; the only visible targets were light emitting diodes (LEDs), mounted on poles, at the apices of the triangle. The LEDs were mounted so that one or two could be used in a trial; if two were used the distance between them was varied horizontally (in experiment 1) and vertically (in experiment 2). The subjects walked around the course under a range of conditions, including two ‘optimal trials’ in full light. The LEDs were flashed for 1 ms at frequencies of 0.5, 1 and 5 Hz in experiment 1 and at 1 and 5 Hz in experiment 2. Mobility was measured with the use of an ultrasonic locator system which measured the subject's position on the course 10 times per second. The mean velocity of the subject in traversing the course was significantly reduced when the flash rate was slower, when the subject had one eye occluded, or when there was only one LED on the pole; when the spacing between the LEDs was varied, either vertically or horizontally performance was unaffected. These results imply that the frequency of updating of visual information is important in determining mobility performance, as are binocular cues, but that local motion parallax is not important. The number of LEDs on each pole had a significant effect on mobility performance: an ‘object’ (two lights) gave more information than a point reference.

Sign in / Sign up

Export Citation Format

Share Document