scholarly journals Violent expiratory events: on coughing and sneezing

2014 ◽  
Vol 745 ◽  
pp. 537-563 ◽  
Author(s):  
Lydia Bourouiba ◽  
Eline Dehandschoewercker ◽  
John W. M. Bush
Keyword(s):  
Fluid Dynamics ◽  
Theoretical Model ◽  
Respiratory Diseases ◽  
Theoretical Models ◽  
Respiratory Pathogens ◽  
Respiratory Events ◽  
Continuous Models ◽  
Analogue Experiments ◽  
Settling Speed ◽  
Turbulent Fluids

AbstractViolent respiratory events such as coughs and sneezes play a key role in transferring respiratory diseases between infectious and susceptible individuals. We present the results of a combined experimental and theoretical investigation of the fluid dynamics of such violent expiratory events. Direct observation of sneezing and coughing events reveals that such flows are multiphase turbulent buoyant clouds with suspended droplets of various sizes. Our observations guide the development of an accompanying theoretical model of pathogen-bearing droplets interacting with a turbulent buoyant momentum puff. We develop in turn discrete and continuous models of droplet fallout from the cloud in order to predict the range of pathogens. According to the discrete fallout model droplets remain suspended in the cloud until their settling speed matches that of the decelerating cloud. A continuous fallout model is developed by adapting models of sedimentation from turbulent fluids. The predictions of our theoretical models are tested against data gathered from a series of analogue experiments in which a particle-laden cloud is ejected into a relatively dense ambient. Our study highlights the importance of the multiphase nature of respiratory clouds, specifically the suspension of the smallest drops by circulation within the cloud, in extending the range of respiratory pathogens.

Investigation on penetration model of shaped charge jet in water

2016 ◽  
Vol 30 (02) ◽  
pp. 1550268 ◽  
Author(s):  
Jinwei Shi ◽  
Xingbai Luo ◽  
Jinming Li ◽  
Jianwei Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Model Simulation ◽  
Theoretical Models ◽  
Theoretical Research ◽  
Water Medium ◽  
Simulation Results ◽  
Jet Penetration ◽  
The Impact ◽  
Penetration Velocity

To analyze the process of jet penetration in water medium quantitatively, the properties of jet penetration spaced target with water interlayer were studied through test and numerical simulation. Two theoretical models of jet penetration in water were proposed. The theoretical model 1 was established considering the impact of the shock wave, combined with the shock equation Rankine–Hugoniot and the virtual origin calculation method. The theoretical model 2 was obtained by fitting theoretical analysis and numerical simulation results. The effectiveness and universality of the two theoretical models were compared through the numerical simulation results. Both the models can reflect the relationship between the penetration velocity and the penetration distance in water well, and both the deviation and stability of theoretical model 1 are better than 2, the lower penetration velocity, and the larger deviation of the theoretical model 2. Therefore, the theoretical model 1 can reflect the properties of jet penetration in water effectively, and provide the reference of model simulation and theoretical research.

Alveolar macrophages: novel therapeutic targets for respiratory diseases

2021 ◽  
Vol 23 ◽  
Author(s):  
Pamelia N. Lim ◽  
Maritza M. Cervantes ◽  
Linh K. Pham ◽  
Alissa C. Rothchild
Keyword(s):  
Alveolar Macrophages ◽  
Respiratory Diseases ◽  
Severe Disease ◽  
Pulmonary Inflammation ◽  
Therapeutic Targets ◽  
Therapeutic Strategies ◽  
Lung Damage ◽  
Respiratory Pathogens ◽  
Inhaled Antibiotics ◽  
Potential Risks

Abstract Alveolar macrophages (AMs) are lung-resident myeloid cells that sit at the interface of the airway and lung tissue. Under homeostatic conditions, their primary function is to clear debris, dead cells and excess surfactant from the airways. They also serve as innate pulmonary sentinels for respiratory pathogens and environmental airborne particles and as regulators of pulmonary inflammation. However, they have not typically been viewed as primary therapeutic targets for respiratory diseases. Here, we discuss the role of AMs in various lung diseases, explore the potential therapeutic strategies to target these innate cells and weigh the potential risks and challenges of such therapies. Additionally, in the context of the COVID-19 pandemic, we examine the role AMs play in severe disease and the therapeutic strategies that have been harnessed to modulate their function and protect against severe lung damage. There are many novel approaches in development to target AMs, such as inhaled antibiotics, liposomal and microparticle delivery systems, and host-directed therapies, which have the potential to provide critical treatment to patients suffering from severe respiratory diseases, yet there is still much work to be done to fully understand the possible benefits and risks of such approaches.

scholarly journals A relação entre ciência e tecnologia a partir de três modelos teóricos distintos

DoisPontos ◽  
2015 ◽  
Vol 12 (1) ◽  
Author(s):  
Gilmar Evandro Szczepanik
Keyword(s):  
Theoretical Model ◽  
Science And Technology ◽  
Theoretical Models ◽  
The Third

resumo: Este artigo tem por objetivo explorar as possíveis relações estabelecidas entre ciência e a tecnologia a partir de três modelos teóricos distintos. O primeiro modelo teórico é chamado de hierárquico e pressupõe uma relação de subordinação entre ciência e a tecnologia. O segundo modelo é denominado de não hierárquico e sustenta que ciência e a tecnologia se encontram fundidas de tal modo que não faz mais sentido tentar entendê-las separadamente. Por fim, o terceiro modelo teórico designado de emancipatório explora alguns elementos que permitem compreender a ciência e a tecnologia ainda como atividades distintas, embora possam trabalhar conjuntamente algumas vezes.Abstract:  This paper aims to  understand the possible  relations between science and technology from three different theoretical models. The first theoretical model is called hierarchical and implies a subordinate relationship between science and technology. The second model  is  called non-hierarchical  and argues  that  science  and technology are fused so that it makes more sense to try to understand them separately. Finally, the third theoretical model is called emancipatory  and explores some elements that allow us to understand science and technology as separate activities, although they may sometimes work together. 

scholarly journals Rapid pivot feeding in pipefish: flow effects on prey and evaluation of simple dynamic modelling via computational fluid dynamics

2008 ◽  
Vol 5 (28) ◽  
pp. 1291-1301 ◽  
Author(s):  
Sam Van Wassenbergh ◽  
Peter Aerts
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Analytical Model ◽  
Dynamic Modelling ◽  
Head Rotation ◽  
Theoretical Models ◽  
Cfd Simulations ◽  
Deceleration Phase ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Effects

Most theoretical models of unsteady aquatic movement in organisms assume that including steady-state drag force and added mass approximates the hydrodynamic force exerted on an organism's body. However, animals often perform explosively quick movements where high accelerations are realized in a few milliseconds and are followed closely by rapid decelerations. For such highly unsteady movements, the accuracy of this modelling approach may be limited. This type of movement can be found during pivot feeding in pipefish that abruptly rotate their head and snout towards prey. We used computational fluid dynamics (CFD) to validate a simple analytical model of cranial rotation in pipefish. CFD simulations also allowed us to assess prey displacement by head rotation. CFD showed that the analytical model accurately calculates the forces exerted on the pipefish. Although the initial phase of acceleration changes the flow patterns during the subsequent deceleration phase, the accuracy of the analytical model was not reduced during this deceleration phase. Our analysis also showed that prey are left approximately stationary despite the quickly approaching pipefish snout. This suggests that pivot-feeding fish need little or no suction to compensate for the effects of the flow induced by cranial rotation.

scholarly journals Change in the Complexity of the Studied Concepts and Theoretical Models with the Age of the Student

2021 ◽  
pp. 132-136
Author(s):  
Robert V. Maier
Keyword(s):  
Theoretical Model ◽  
Theoretical Models ◽  
Dependency Graphs

The problem of the dependence of the didactic complexity of the studied concepts and theoretical models on the age of the student (schoolchild, student) is analysed. The complexity of a concept (term) can be characterized by the number of words from a fifth-grader’s thesaurus needed to explain its meaning. To find the complexity of a theoretical model of an object (for example, an atom), it is necessary to sum up the complexities of all the words that make up the description of the model and take into account the indicator of the variety of terms. Dependency graphs were built: 1) the complexity of the most difficult terms for understanding from the year of study; 2) the complexity of various theoretical models of the atom from the year of study at school and university. In both cases, the resulting curves are ascending, like a parabola, corresponding to an increase in complexity by almost a hundred times.

Acoustic invisibility in turbulent fluids by optimised cloaking

2014 ◽  
Vol 749 ◽  
pp. 460-477 ◽  
Author(s):  
Xun Huang ◽  
Siyang Zhong ◽  
Xin Liu
Keyword(s):  
Theoretical Model ◽  
Computational Methods ◽  
Physical Mechanism ◽  
Far Field ◽  
Turbulent Wakes ◽  
Scattered Fields ◽  
Turbulent Fluids

AbstractAcoustic invisibility of a cloaking system in turbulent fluids is poorly understood. Here we show that evident scattering would appear in turbulent wakes due to the submergence of a classical cloaking device. The inherent physical mechanism is explained using our theoretical model, which eventually inspires us to develop an optimised cloaking approach. Both the near- and far-field scattered fields are examined using computational methods. The remarkably low scattering demonstrates the effectiveness of the proposed approach, in particular for acoustic cloaking in turbulent fluids.

Retrieval of Bio-Geophysical Parameters from Remotely Sensing Data by Using Bayesian Methodology

2007 ◽  
pp. 222-252
Author(s):  
C. Notarnicola
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Theoretical Models ◽  
Data Sets ◽  
Model Errors ◽  
Sources Of Information ◽  
Remotely Sensed Data ◽  
Bayesian Methodology ◽  
Information Models ◽  
Bayesian Methodologies

This chapter introduces the use of Bayesian methodology for inversion purposes: the extraction of bio-geophysical parameters from remotely sensed data. Multisources information, such as different polarizations, frequencies, and sensors are fundamental to the development of operationally useful inversion systems. In this context, Bayesian methodologies offer a convenient tool of combining two or more disparate sources of information, models, and data. The chapter describes the development of a general model starting from a theoretical model, including the sensor noise and the model errors, by using a Bayesian approach. Furthermore, the developed procedure is applied to some experimental data sets. The author hopes that considering theoretical models and experimental data in many different configurations can give an idea of the versatility and robustness of the Bayesian framework.

Design and Compiling of Laser Propagation Simulation Software in Atmospheric Environment

2012 ◽  
Vol 490-495 ◽  
pp. 2136-2140
Author(s):  
Tong Gang Zhao ◽  
Zhi Qiang Zhang
Keyword(s):  
Theoretical Model ◽  
Rayleigh Scattering ◽  
Hot Spot ◽  
Theoretical Models ◽  
Mie Scattering ◽  
Simulation System ◽  
Simulation Software ◽  
Atmospheric Environment ◽  
Laser Propagation ◽  
Atmospheric Propagation

As development of laser technology, the characteristic of laser atmospheric propagation is always hot spot in laser domain. Using theoretical models of laser atmospheric propagation, a simulation system is researched by implementing a scientific method of software development. This simulation system can simulate the radiate property of laser propagation in atmosphere, and demonstrate the course of laser propagation. This theoretical model of atmospheric propagation is based on Lambert-Beer law, combined with other classic theoretical model such as Rayleigh scattering and Mie scattering. Multiple scattering theories are used when simulating the laser propagation in smoke or fog. In calculation, the atmosphere is divided into layer. An appropriate model will be selected for calculation in each layer in order to enhance the stimulation precision. Lastly, the figure of light spot is drawn along with transmission space. Laser atmospheric propagation is demonstrated.

scholarly journals Monitoring the Quality of Services in Electronic Banking

2016 ◽  
Vol 5 (3) ◽  
pp. 99-119 ◽  
Author(s):  
Radislav Jovovic ◽  
Elvis Lekic ◽  
Miroslav Jovovic
Keyword(s):  
Theoretical Model ◽  
Quantitative Research ◽  
Theoretical Models ◽  
Quality Of Services ◽  
Electronic Banking ◽  
Significant Information ◽  
Time Activity ◽  
Banking Services ◽  
Quantitative Research Methods

Abstract Successful development of electronic banking is in direct correlation with the quality of services in electronic banking. Therefore, it is necessary that the banks are familiar with the attributes of electronic services on which clients assess the bank’s quality and client’s satisfaction with them, in order to be able to monitor, correct and improve the performance of electronic banking. We start from the hypothesis that there are already developed theoretical models for measuring the quality of e-banking services but they must be adjusted to the specific environment that is analysed in order to obtain reliable and quality information. The qualitative and quantitative research methods are applied in this paper in order to a get adjusted theoretical model (instrument) for measuring the quality of electronic banking services. As a result of the conducted analysis, the initial theoretical model has been modified, so that the final version of the model (instrument) for measuring quality of online banking allows obtaining reliable data, and information in the particular environment. And the results are: significant information about the quality of e-banking, modified theoretical model, information about the dimensions of quality of e-banking, customer satisfaction, and pathways and guidelines for the improvement of e-banking. The measuring of quality of electronic banking services in not one time activity but repeated one, as permanent monitoring strategy. This research is widely applicable even though it was conducted in the context of Montenegrin e-banking, since most of the banks in Montenegro are owned by well-known European banks, and it is expected that the obtained knowledge and information can be generalized.

The Arithmetic of Navigation Position Errors

1982 ◽  
Vol 35 (1) ◽  
pp. 28-38
Author(s):  
J. B. Parker
Keyword(s):  
Theoretical Model ◽  
Probability Density ◽  
Goodness Of Fit ◽  
Theoretical Models ◽  
Double Exponential Distribution ◽  
Position Errors ◽  
Double Exponential ◽  
The Family ◽  
Exponential Power ◽  
Image Position

In a notable series of articles, Hsu advances theoretical models which are used to graduate 7582 observations of aircraft lateral deviations. The goodness of fit of these models, as judged by the χ2 test, is satisfactory. Hsu's main theoretical model is the Double Double Exponential distribution (DDE), a three parameter model whose probability density function is given byOther model types are also considered, such as the family of exponential power distributions whose probability density is cited by Hsu insection 9. This leads to a four-parameter model, and the fit is (not surprisingly) better even than that of the DDE.

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