Role of the diaphragm in chest wall mechanics

1992 ◽  
Vol 72 (2) ◽  
pp. 568-574 ◽  
Author(s):  
O. Lichtenstein ◽  
S. A. Ben-Haim ◽  
G. M. Saidel ◽  
U. Dinnar
Keyword(s):  
Mathematical Model ◽  
Flat Surface ◽  
Abdominal Cavity ◽  
Gastric Distension ◽  
Rib Cage ◽  
Chest Wall Mechanics ◽  
Human Experiments ◽  
General Mathematical Model ◽  
Thoracic And Abdominal

We analyzed three different assumptions about diaphragm function that determine the thoracoabdominal interaction. In the simplest case, the diaphragm is assumed to be a completely flaccid membrane serving only to partition the thorax and the abdominal cavity. In the second case, it is assumed to have a finite tension but to maintain a relatively flat surface at the base of the rib cage (i.e., a negligible zone of apposition). In the general case, it is assumed that the diaphragm has finite tension and its position may vary (i.e., permitting a zone of apposition). These possible modes of behavior are incorporated into a mathematical model of ventilatory system mechanics that distinguishes the diaphragm, lung, abdomen, and rib cage. The significance of these modes is examined with respect to data from human experiments in which gas or liquid is introduced into the pleural or abdominal spaces, causing a volume change (Vep). We show that the Vep effect on the thoracic and abdominal volumes is sensitive to diaphragm mechanics and depends on the nature of the Vep: gastric distension (with water or air) or pneumothorax. Only the behavior of the general model is consistent with physiological observations, especially the distribution of Vep. Our general mathematical model can quantitatively predict this behavior.

The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

2020 ◽  
pp. 108-115 ◽  
Author(s):  
Vladimir P. Budak ◽  
Anton V. Grimaylo
Keyword(s):  
Mathematical Model ◽  
Light Field ◽  
Global Illumination ◽  
Multiple Reflections ◽  
Software Environment ◽  
The Monte Carlo Method ◽  
Mueller Matrices ◽  
Volume Integration ◽  
The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

The Role of Laparoscopic Technology in the Diagnosis and Treatment of Acute Surgical Pathologies of the Abdominal Cavity Organs

2018 ◽  
Vol 3 (2) ◽  
pp. 175-180
Author(s):  
F. G. Jamalov ◽  
◽  
M. M. Abdullaev ◽  
E. V. Nabieva ◽  
Т. P. Jamalova ◽  
...  
Keyword(s):  
Abdominal Cavity ◽  
Diagnosis And Treatment

The Generation Principle and Mathematical Models of Double-Enveloping Internal Gear Pairs

2015 ◽  
Author(s):  
Xuan Li ◽  
Bingkui Chen ◽  
Yawen Wang ◽  
Guohua Sun ◽  
Teik C. Lim
Keyword(s):  
Mathematical Model ◽  
Load Capacity ◽  
Geometrical Shape ◽  
Gear Pair ◽  
Numerical Examples ◽  
Proposed Model ◽  
General Mathematical Model ◽  
Meshing Characteristics ◽  
Internal Gear ◽  
Tooth Pair

In this paper, the planar double-enveloping method is presented for the generation of tooth profiles of the internal gear pair for various applications, such as gerotors and gear reducers. The main characteristic of this method is the existence of double contact between one tooth pair such that the sealing property, the load capacity and the transmission precision can be significantly improved as compared to the conventional configuration by the single-enveloping theory. Firstly, the generation principle of the planar double-enveloping method is introduced. Based on the coordinate transformation and the envelope theory, the general mathematical model of the double-enveloping internal gear pair is presented. By using this model, users can directly design different geometrical shape profiles to obtain a double-enveloping internal gear pair with better meshing characteristics. Secondly, to validate the effectiveness of the proposed model, specific mathematical formulations of three double-enveloping internal gear pairs which apply circular, parabolic and elliptical curves as the generating curves are given. The equations of tooth profiles and meshing are derived and the composition of tooth profiles is analyzed. Finally, numerical examples are provided for an illustration.

scholarly journals The Mathematical Model for Total Pubertal Growth in Idiopathic Growth Hormone (GH) Deficiency Suggests a Moderate Role of GH Dose

2003 ◽  
Vol 88 (10) ◽  
pp. 4748-4753 ◽  
Author(s):  
Michael B. Ranke ◽  
Anders Lindberg ◽  
David D. Martin ◽  
Bert Bakker ◽  
Patrick Wilton ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Growth Hormone ◽  
Gh Deficiency ◽  
Pubertal Growth ◽  
The Mathematical Model

scholarly journals A Control Based Mathematical Model for the Evaluation of Intervention Lines in COVID-19 Epidemic Spread: The Italian Case Study

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 890
Author(s):  
Paolo Di Giamberardino ◽  
Rita Caldarella ◽  
Daniela Iacoviello
Keyword(s):  
Mathematical Model ◽  
Equilibrium Points ◽  
Italian Case ◽  
Control Actions ◽  
Containment Measures ◽  
Asymptomatic Subjects ◽  
The Impact

This paper addresses the problem of describing the spread of COVID-19 by a mathematical model introducing all the possible control actions as prevention (informative campaign, use of masks, social distancing, vaccination) and medication. The model adopted is similar to SEIQR, with the infected patients split into groups of asymptomatic subjects and isolated ones. This distinction is particularly important in the current pandemic, due to the fundamental the role of asymptomatic subjects in the virus diffusion. The influence of the control actions is considered in analysing the model, from the calculus of the equilibrium points to the determination of the reproduction number. This choice is motivated by the fact that the available organised data have been collected since from the end of February 2020, and almost simultaneously containment measures, increasing in typology and effectiveness, have been applied. The characteristics of COVID-19, not fully understood yet, suggest an asymmetric diffusion among countries and among categories of subjects. Referring to the Italian situation, the containment measures, as applied by the population, have been identified, showing their relation with the government's decisions; this allows the study of possible scenarios, comparing the impact of different possible choices.

Abstract P432: Higher Muscle-to-Abdominal Cavity Ratio is Associated with Lower Odds of Type II Diabetes in Older Women

Circulation ◽  
2013 ◽  
Vol 127 (suppl_12) ◽  
Author(s):  
Britta Larsen ◽  
Matthew Allison ◽  
Eugene Kang ◽  
Sarah Saad ◽  
Gail A Laughlin ◽  
...  
Keyword(s):  
Type Ii Diabetes ◽  
Abdominal Cavity ◽  
Abdominal Muscle ◽  
Normal Weight ◽  
Area Ratio ◽  
Type Ii ◽  
Obese Women ◽  
Abdominal Adipose Tissue ◽  
Race Ethnicity

Background: Excess abdominal adipose tissue has been identified as an important factor in the development of type II diabetes. Lean muscle tissue also plays an important role in glucose regulation, yet research on the role of muscle in diabetes etiology is limited. Abdominal muscle mass could be particularly relevant for normal weight diabetics, for whom excessive abdominal adipose tissue may play less of a role. Objective: To explore the association between muscle-to-abdominal cavity area ratio and prevalent diabetes in older community-dwelling women in the Rancho Bernardo Study, UCSD Filipino Women’s Health Study, and the Health Assessment Study of African-American Women. Methods: Participants were 421 women (40% Caucasian, 28% Filipina, 32% African American) with a mean age of 64 (6.9) years. Abdominal muscle and fat areas were measured using computed tomography (CT) scans, and were used to compute a muscle-to-abdominal cavity area ratio (MACR). Based on body mass index (BMI), participants were classified as normal weight (18-24.9 kg/m2), overweight (25-29.9), or obese (30+). Prevalent diabetes was defined as self-report of physician diagnosis, anti-diabetes medication use, fasting morning glucose ≥ 126 mg/dL or 2 hour glucose ≥ 200mg/dL. MACR was modeled per standard deviation (SD) and logistic regression was used to examine the association with diabetes while adjusting for relevant covariates. Results: Prevalent diabetes was seen in 12.8% of the sample (54 of 421). In age and race/ethnicity adjusted models, each SD increase in MACR was associated with significant reduced odds of diabetes (OR = 0.62, CI: 0.43-0.89, p = 0.01), which remained significant after further adjustment for BMI category, smoking, physical activity, hypertension, anti-hypertensive drugs, and estrogen use (OR = 0.64, CI: 0.41-0.98, p = .041). The association was modestly attenuated after further adjusting for visceral fat area (OR = 0.70, CI: 0.44-1.10, p = 0.12). Normal weight women with diabetes had significantly less total muscle (p = 0.045) and smaller MACR’s (p = 0.001) than those without diabetes, while this was not seen for overweight or obese women with diabetes. Stratified by BMI category, MACR was significantly associated with lower odds of diabetes for normal weight women across all three models (fully adjusted OR = 0.37, CI: 0.15-0.90, p =.03), yet was not associated with diabetes in any models for women who were overweight or obese (all p > 0.50). Interactions of MACR with race/ethnicity were not significant. Conclusions: Muscle-to-abdominal cavity ratio is associated with reduced likelihood of type II diabetes in women. This association differs by BMI category, with muscle showing the greatest protection in normal weight women, and no effect in overweight or obese women. This highlights the potential role of low muscle mass as a risk factor for diabetes, particularly in women who may appear to be at low risk.

Nitric oxide: a new role in intensive care

2020 ◽  
Vol 22 (1) ◽  
pp. 72-79
Author(s):  
Alexandra Lee ◽  
◽  
Warwick Butt ◽  
◽  
◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Potential Role ◽  
Nitric Oxide Donors ◽  
Ischaemia Reperfusion Injury ◽  
Surface Receptors ◽  
The Past ◽  
Ischaemia Reperfusion ◽  
Human Experiments ◽  
Endogenous Nitric Oxide

Inhaled nitric oxide has been used for 30 years to improve oxygenation and decrease pulmonary vascular resistance. In the past 15 years, there has been increased understanding of the role of endogenous nitric oxide on cell surface receptors, mitochondria, and intracellular processes involving calcium and superoxide radicals. This has led to several animal and human experiments revealing a potential role for administered nitric oxide or nitric oxide donors in patients with systemic inflammatory response syndrome or ischaemia–reperfusion injury, and in patients for whom exposure of blood to artificial surfaces has occurred.

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