Pressure Changes Induced by Whole Body Acceleration Shocks

1991 ◽  
Vol 113 (1) ◽  
pp. 27-29 ◽  
Author(s):  
E. Belardinelli ◽  
M. Ursino ◽  
G. Fabbri ◽  
A. Cevese ◽  
F. Schena
Keyword(s):  
Mathematical Model ◽  
Carotid Artery ◽  
Normal Pressure ◽  
Compressed Air ◽  
Whole Body ◽  
Body Acceleration ◽  
Vascular Bed ◽  
Pressure Changes ◽  
The Mathematical Model

In the present paper pressure changes induced by sudden body acceleration are studied “in vivo” on the dog and compared to the results obtainable with a recently developed mathematical model. A dog was fixed to a movable table, which was accelerated by a compressed air piston for less than 1 s. Acceleration was varied by changing the air pressure in the piston. Pressure was measured during the experiment at different points along the vascular bed. However, only data obtained in the carotid artery and abdominal aorta are presented here. The results demonstrated that impulse body accelerations cause significant pressure peaks in the vessel examined (about + 25 mmHg in the carotid artery with body acceleration of g/2). Moreover, pressure changes are rapidly damped, with a time constant of about 0.1s. From the present results it may be concluded that, according to the prediction of the mathematical model, body accelerations such as those occurring in normal life can induce pressure changes well beyond the normal pressure value.

scholarly journals Change of photosensitizer fluorescence at its diffusion in viscous liquid flow

2016 ◽  
Vol 09 (02) ◽  
pp. 1650005 ◽  
Author(s):  
Valeriya S. Maryakhina ◽  
Vyacheslav V. Gun’kov
Keyword(s):  
Mathematical Model ◽  
Viscous Liquid ◽  
Liquid Flow ◽  
Fluorescence Spectra ◽  
Inflection Point ◽  
Biological Tissues ◽  
Transparency Window ◽  
Biological Liquid ◽  
The Mathematical Model

In this paper, the mathematical model of distribution of the injected compound in biological liquid flow has been described. It is considered that biological liquid contains a few phases such as water, peptides and cells. The injected compound (for example, photosensitizer) can interact with peptides and cells. At the time, viscosity of the biological liquid depends on pathology present in organism. The obtained distribution of the compound connects on changes of its fluorescence spectra which are registered during fluorescent diagnostics of tumors. It is obtained that the curves do not have monotonic nature. There is a sharp curves decline in the first few seconds after injection. Intensivity of curves rises after decreasing. It is especially pronounced for wavelength 590[Formula: see text]nm and 580[Formula: see text]nm (near the “transparency window” of biological tissues). Time of inflection point shifts from 8.4[Formula: see text]s to 6.9[Formula: see text]s for longer wavelength. However, difference between curves is little for different viscosity means of the biological liquid. Thus, additional pathology present in organism does not impact to the results of in vivo biomedical investigations.

scholarly journals Modelling Methodology of Piston Pneumatic Air Engine Operation

2019 ◽  
Vol 13 (4) ◽  
pp. 271-278
Author(s):  
Dariusz Szpica ◽  
Michal Korbut
Keyword(s):  
Mathematical Model ◽  
Exhaust System ◽  
Compressed Air ◽  
System Control ◽  
Engine Operation ◽  
Air Supply ◽  
Mechanical Subsystem ◽  
Modelling Methodology ◽  
Lumped Elements ◽  
The Mathematical Model

Abstract The article presents a mathematical model describing the operation of a piston pneumatic air engine. Compressed air engines are an alternative to classic combustion solutions as they do not directly emit toxic exhaust components. In the study, a modified internal combustion piston engine was adopted as pneumatic engine. The mathematical model was divided on the two subsystems, that is, mechanical and pneumatic. The mechanical subsystem describes a transformation of compressed air supply process parameters to energy transferred to the piston and further the conversion of the translational to rotary motion; in turn, in the pneumatic part, the lumped elements method was used. Calculations were carried out using the Matlab-Simulink software, resulting in the characteristics of external and economic indicators. The presented mathematical model can be ultimately developed with additional elements, such as the intake or exhaust system, as well as timing system control.

scholarly journals In vivo imaging of the kinetics of microglial self-renewal and maturation in the adult visual cortex

2020 ◽  
Author(s):  
Monique S. Mendes ◽  
Jason Atlas ◽  
Zachary Brehm ◽  
Antonio Ladron-de-Guevara ◽  
Matthew N. McCall ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Visual Cortex ◽  
Adult Brain ◽  
Self Renewal ◽  
Two Photon ◽  
And Migration ◽  
The Mathematical Model ◽  
Kinetics Of ◽  
The Brain

AbstractMicroglia are the resident immune cells in the brain with the capacity to autonomously self-renew. Under basal conditions, microglial self-renewal appears to be slow and stochastic, although microglia have the ability to proliferate very rapidly following depletion or in response to injury. Because microglial self-renewal has largely been studied using static tools, the mechanisms and kinetics by which microglia renew and acquire mature characteristics in the adult brain are not well understood. Using chronic in vivo two-photon imaging in awake mice and PLX5622 (Colony stimulating factor 1 receptor (CSF1R) inhibitor) to deplete microglia, we set out to understand the dynamic self-organization and maturation of microglia following depletion in the visual cortex. We confirm that under basal conditions, cortical microglia show limited turnover and migration. Following depletion, however, microglial repopulation is remarkably rapid and is sustained by the dynamic division of the remaining microglia in a manner that is largely independent of signaling through the P2Y12 receptor. Mathematical modeling of microglial division demonstrates that the observed division rates can account for the rapid repopulation observed in vivo. Additionally, newly-born microglia resemble mature microglia, in terms of their morphology, dynamics and ability to respond to injury, within days of repopulation. Our work suggests that microglia rapidly self-renew locally, without the involvement of a special progenitor cell, and that newly born microglia do not recapitulate a slow developmental maturation but instead quickly take on mature roles in the nervous system.Graphical Abstract(a) Microglial dynamics during control condition. Cartoon depiction of the heterogenous microglia in the visual cortex equally spaced. (b) During the early stages of repopulation, microglia are irregularly spaced and sparse. (c) During the later stages of repopulation, the number of microglia and the spatial distribution return to baseline. (d-f) We then created and ran a mathematical model that sampled the number of microglia, (d) the persistent doublets, (e) the rapid divisions of microglia and (f) the secondary divisions of microglia during the peak of repopulation day 2-day 3. The mathematical model suggested that residual microglia can account for the rapid repopulation we observed in vivo.

scholarly journals Working Characteristics of Variable Intake Valve in Compressed Air Engine

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Qihui Yu ◽  
Yan Shi ◽  
Maolin Cai
Keyword(s):  
Mathematical Model ◽  
Energy Utilization ◽  
Utilization Efficiency ◽  
Compressed Air ◽  
Maximum Output ◽  
Output Torque ◽  
Good Consistency ◽  
Intake Pressure ◽  
Set Up ◽  
The Mathematical Model

A new camless compressed air engine is proposed, which can make the compressed air energy reasonably distributed. Through analysis of the camless compressed air engine, a mathematical model of the working processes was set up. Using the software MATLAB/Simulink for simulation, the pressure, temperature, and air mass of the cylinder were obtained. In order to verify the accuracy of the mathematical model, the experiments were conducted. Moreover, performance analysis was introduced to design compressed air engine. Results show that, firstly, the simulation results have good consistency with the experimental results. Secondly, under different intake pressures, the highest output power is obtained when the crank speed reaches 500 rpm, which also provides the maximum output torque. Finally, higher energy utilization efficiency can be obtained at the lower speed, intake pressure, and valve duration angle. This research can refer to the design of the camless valve of compressed air engine.

scholarly journals Correlation between Animal and Mathematical Models for Prostate Cancer Progression

2009 ◽  
Vol 10 (4) ◽  
pp. 241-252 ◽  
Author(s):  
Z. Jackiewicz ◽  
C. L. Jorcyk ◽  
M. Kolev ◽  
B. Zubik-Kowal
Keyword(s):  
Mathematical Model ◽  
Cancer Progression ◽  
Growth Rates ◽  
Numerical Solutions ◽  
Initial Conditions ◽  
Tumour Progression ◽  
Prostate Cancer Progression ◽  
The Mathematical Model

This work demonstrates that prostate tumour progressionin vivocan be analysed by using solutions of a mathematical model supplemented by initial conditions chosen according to growth rates of cell linesin vitro. The mathematical model is investigated and solved numerically. Its numerical solutions are compared with experimental data from animal models. The numerical results confirm the experimental results with the growth ratesin vivo.

Cerebral hemodynamics during arterial and CO2 pressure changes: in vivo prediction by a mathematical model

2000 ◽  
Vol 279 (5) ◽  
pp. H2439-H2455 ◽  
Author(s):  
M. Ursino ◽  
A. Ter Minassian ◽  
C. A. Lodi ◽  
L. Beydon
Keyword(s):  
Mathematical Model ◽  
Clinical Investigation ◽  
Systemic Arterial Pressure ◽  
Cerebral Hemodynamics ◽  
Individual Identification ◽  
Doppler Velocity ◽  
Parameter Estimates ◽  
Measured Time ◽  
Pressure Changes

The aim of this work was to analyze changes in cerebral hemodynamics and intracranial pressure (ICP) evoked by mean systemic arterial pressure (SAP) and arterial CO2 pressure (PaCO2 ) challenges in patients with acute brain damage. The study was performed by means of a new simple mathematical model of intracranial hemodynamics, particularly aimed at routine clinical investigation. The model was validated by comparing its results with data from transcranial Doppler velocity in the middle cerebral artery ( V MCA) and ICP measured in 44 tracings on 13 different patients during mean SAP and PaCO2 challenges. The validation consisted of individual identification of 6 parameters in all 44 tracings by means of a best fitting algorithm. The parameters chosen for the identification summarize the main aspects of intracranial dynamics, i.e., cerebrospinal fluid circulation, intracranial elastance, and cerebrovascular control. The results suggest that the model is able to reproduce the measured time patterns of V MCA and ICP in all 44 tracings by using values for the parameters that lie within the ranges reported in the pathophysiological literature. The meaning of parameter estimates is discussed, and comments on the main virtues and limitations of the present approach are offered.

Dimensionless Study on Efficiency and Speed Characteristics of a Compressed Air Engine

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Qihui Yu ◽  
Maolin Cai ◽  
Yan Shi ◽  
Chi Yuan
Keyword(s):  
Mathematical Model ◽  
Reference Values ◽  
Engine Performance ◽  
Power Source ◽  
Compressed Air ◽  
Working Process ◽  
Ic Engine ◽  
Rotating Speed ◽  
Inertia Parameter ◽  
The Mathematical Model

To eliminate the pollutants exhausting, this paper presents an idea of using compressed air as the power source for engines. Instead of an internal combustion (IC) engine, this automobile is equipped with a compressed air engines (CAEs), which transforms the energy of the compressed air into mechanical kinematic energy. Through analysis of the working process of a CAE, the mathematical model is setup. Experiments are carried out to verify the engine performance and the basic model’s validity. By selecting the appropriate reference values, the mathematical model is transformed to a dimensionless expression. The dimensionless speed and efficiency characteristics of the CAE are obtained. Through analysis, it can be obtained that the dimensionless average rotating speed is mainly determined by the intake duration angle, the dimensionless inertia parameter, the dimensionless exhaust pressure, and the scale factor of exhaust valve. Moreover, the efficiency of the CAE is mainly determined by the dimensionless exhaust pressure, the intake duration angle and the dimensionless cylinder clearance. This research can be referred to in the design of CAE and the study on optimization of the CAE.

An Experimental Study of Package Cushioning for the Human Head

1976 ◽  
Vol 43 (3) ◽  
pp. 469-474
Author(s):  
Y. King Liu ◽  
K. B. Chandran
Keyword(s):  
Mathematical Model ◽  
Animal Experiments ◽  
Human Head ◽  
Head Impacts ◽  
Closed Head ◽  
The Mathematical Model ◽  
Experimental Pressure ◽  
The Brain ◽  
Good Agreement

An experiment was performed to determine the container acceleration and pressure distribution in a Plexiglass cylinder, filled either with water or 3 percent set-gelatin, and impacted against a wall. This experiment serves to quantitatively validate a theoretical model simulating an one-dimensional closed-head impact given earlier. The experiments showed important differences between the theoretical and experimental pressure measurements. When the medium contained within the cylinder was water the coup pressure as found by experiment, was higher than the mathematical model prediction while the contrecoup pressure was in good agreement. When the container was filled with a set gel, the coup pressure was in agreement with the mathematical model but the contrecoup pressure is considerably lower than the calculated result. Since the brain is neither water nor gel, in vivo animal experiments are needed to obtain meaningful tolerance limits for injury due to cavitation at the contrecoup region in closed-head impacts.

scholarly journals Experimental and mathematical modelling of magnetically labelled mesenchymal stromal cell delivery

2021 ◽  
Vol 18 (175) ◽  
pp. 20200558
Author(s):  
E. F. Yeo ◽  
H. Markides ◽  
A. T. Schade ◽  
A. J. Studd ◽  
J. M. Oliver ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Magnetic Nanoparticles ◽  
Mathematical Modelling ◽  
Magnetic Targeting ◽  
Cell Capture ◽  
Cell Therapies ◽  
External Magnet ◽  
The Mathematical Model

A key challenge for stem cell therapies is the delivery of therapeutic cells to the repair site. Magnetic targeting has been proposed as a platform for defining clinical sites of delivery more effectively. In this paper, we use a combined in vitro experimental and mathematical modelling approach to explore the magnetic targeting of mesenchymal stromal cells (MSCs) labelled with magnetic nanoparticles using an external magnet. This study aims to (i) demonstrate the potential of magnetic tagging for MSC delivery, (ii) examine the effect of red blood cells (RBCs) on MSC capture efficacy and (iii) highlight how mathematical models can provide both insight into mechanics of therapy and predictions about cell targeting in vivo. In vitro MSCs are cultured with magnetic nanoparticles and circulated with RBCs over an external magnet. Cell capture efficacy is measured for varying magnetic field strengths and RBC percentages. We use a 2D continuum mathematical model to represent the flow of magnetically tagged MSCs with RBCs. Numerical simulations demonstrate qualitative agreement with experimental results showing better capture with stronger magnetic fields and lower levels of RBCs. We additionally exploit the mathematical model to make hypotheses about the role of extravasation and identify future in vitro experiments to quantify this effect.

Sign in / Sign up

Export Citation Format

Share Document