Affine Versus Non-Affine Fibril Kinematics in Collagen Networks: Theoretical Studies of Network Behavior

2005 ◽  
Vol 128 (2) ◽  
pp. 259-270 ◽  
Author(s):  
Preethi L. Chandran ◽  
Victor H. Barocas
Keyword(s):  
Network Model ◽  
Constitutive Modeling ◽  
Load Transfer ◽  
Critical Role ◽  
Affine Model ◽  
Tissue Equivalents ◽  
Scale Models ◽  
Macroscopic Deformation ◽  
The Individual ◽  
Open Question

The microstructure of tissues and tissue equivalents (TEs) plays a critical role in determining the mechanical properties thereof. One of the key challenges in constitutive modeling of TEs is incorporating the kinematics at both the macroscopic and the microscopic scale. Models of fibrous microstructure commonly assume fibrils to move homogeneously, that is affine with the macroscopic deformation. While intuitive for situations of fibril-matrix load transfer, the relevance of the affine assumption is less clear when primary load transfer is from fibril to fibril. The microstructure of TEs is a hydrated network of collagen fibrils, making its microstructural kinematics an open question. Numerical simulation of uniaxial extensile behavior in planar TE networks was performed with fibril kinematics dictated by the network model and by the affine model. The average fibril orientation evolved similarly with strain for both models. The individual fibril kinematics, however, were markedly different. There was no correlation between fibril strain and orientation in the network model, and fibril strains were contained by extensive reorientation. As a result, the macroscopic stress given by the network model was roughly threefold lower than the affine model. Also, the network model showed a toe region, where fibril reorientation precluded the development of significant fibril strain. We conclude that network fibril kinematics are not governed by affine principles, an important consideration in the understanding of tissue and TE mechanics, especially when load bearing is primarily by an interconnected fibril network.

A Proxy Model for Predicting SAGD Production From Reservoirs Containing Shale Barriers

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Jingwen Zheng ◽  
Juliana Y. Leung ◽  
Ronald P. Sawatzky ◽  
Jose M. Alvarez
Keyword(s):  
Simulation Model ◽  
Network Model ◽  
Reservoir Simulation ◽  
Oil Sands ◽  
Training Set ◽  
Steam Assisted Gravity Drainage ◽  
Proxy Model ◽  
Reservoir Simulation Model ◽  
The Individual ◽  
Operational Constraints

Artificial intelligence (AI) tools are used to explore the influence of shale barriers on steam-assisted gravity drainage (SAGD) production. The data are derived from synthetic SAGD reservoir simulations based on petrophysical properties and operational constraints gathered from the Suncor's Firebag project, which is representative of Athabasca oil sands reservoirs. The underlying reservoir simulation model is homogeneous and two-dimensional. Reservoir heterogeneities are modeled by superimposing sets of idealized shale barrier configurations on this homogeneous reservoir model. The individual shale barriers are categorized by their location relative to the SAGD well pair and by their geometry. SAGD production for a training set of shale barrier configurations was simulated. A network model based on AI tools was constructed to match the output of the reservoir simulation for this training set of shale barrier configurations, with a focus on the production rate and the steam-oil ratio (SOR). Then the trained AI proxy model was used to predict SAGD production profiles for arbitrary configurations of shale barriers. The predicted results were consistent with the results of the SAGD simulation model with the same shale barrier configurations. The results of this work demonstrate the capability and flexibility of the AI-based network model, and of the parametrization technique for representing the characteristics of the shale barriers, in capturing the effects of complex heterogeneities on SAGD production. It offers the significant potential of providing an indirect method for inferring the presence and distribution of heterogeneous reservoir features from SAGD field production data.

scholarly journals Nonlinear visuoauditory integration in the mouse superior colliculus

2021 ◽  
Author(s):  
Shinya Ito ◽  
Yufei Si ◽  
Alan M. Litke ◽  
David A. Feldheim
Keyword(s):  
Superior Colliculus ◽  
Sensory Integration ◽  
Large Scale ◽  
Temporal Dynamics ◽  
Critical Role ◽  
Sensory Information ◽  
Population Level ◽  
Object Identification ◽  
Response Properties ◽  
The Individual

AbstractSensory information from different modalities is processed in parallel, and then integrated in associative brain areas to improve object identification and the interpretation of sensory experiences. The Superior Colliculus (SC) is a midbrain structure that plays a critical role in integrating visual, auditory, and somatosensory input to assess saliency and promote action. Although the response properties of the individual SC neurons to visuoauditory stimuli have been characterized, little is known about the spatial and temporal dynamics of the integration at the population level. Here we recorded the response properties of SC neurons to spatially restricted visual and auditory stimuli using large-scale electrophysiology. We then created a general, population-level model that explains the spatial, temporal, and intensity requirements of stimuli needed for sensory integration. We found that the mouse SC contains topographically organized visual and auditory neurons that exhibit nonlinear multisensory integration. We show that nonlinear integration depends on properties of auditory but not visual stimuli. We also find that a heuristically derived nonlinear modulation function reveals conditions required for sensory integration that are consistent with previously proposed models of sensory integration such as spatial matching and the principle of inverse effectiveness.

scholarly journals Emerging, crystalizing, and changing psychological contracts over time: Introducing the iPC-network model

2019 ◽  
Author(s):  
Tim Vantilborgh
Keyword(s):  
Network Model ◽  
Psychological Contract ◽  
Dynamic Network ◽  
Network Models ◽  
Psychological Contracts ◽  
Exchange Relationships ◽  
Contract Breach ◽  
Alternative Approach ◽  
The Individual ◽  
Over Time

This chapter introduces the individual Psychological Contract (iPC) network model as an alternative approach to study psychological contracts. This model departs from the basic idea that a psychological contract forms a mental schema containing obligated inducements and contributions, which are exchanged for each other. This mental schema is captured by a dynamic network, in which the nodes represent the inducements and contributions and the ties represent the exchanges. Building on dynamic systems theory, I propose that these networks evolve over time towards attractor states, both at the level of the network structure and at the level of the nodes (i.e., breach and fulfilment attractor states). I highlight how the iPC-network model integrates recent theoretical developments in the psychological contract literature and explain how it may advance scholars understanding of exchange relationships. In particular, I illustrate how iPC-network models allow researchers to study the actual exchanges in the psychological contract over time, while acknowledging its idiosyncratic nature. This would allow for more precise predictions of psychological contract breach and fulfilment consequences and explains how content and process of the psychological contract continuously influence each other.

Potential Role of Darvyadi Kwatha in the Management of Diabetes

The Healer ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 80-86
Author(s):  
Shankar Gautam ◽  
Abhishek Upadhyay ◽  
Rashmi Mutha ◽  
BINOD KUMAR SINGH ◽  
Ram Kishor Joshi
Keyword(s):  
Causes Of Death ◽  
Potential Role ◽  
Critical Role ◽  
Animal Experiments ◽  
Safety Evaluation ◽  
New Drugs ◽  
Effective Management ◽  
The Individual ◽  
Glucose 6 Phosphate Dehydrogenase

Diabetes is a clinical condition characterized by a spike in blood glucose in plasma. It is one of the 21st century's greatest public health crises and is among the top 10 causes of death worldwide. Although new drugs and therapeutics are emerging for its management but the prevalence is increasing at an alarming pace; thus, every system must contribute for effective management. An effort is made to review the efficacy and safety evaluation of the individual herbs of Darvyadi Kwatha (DK), an Ayurvedic formulation mentioned in Charaka Samhita. The constituents of the DK has some strong efficient antidiabetic/hypoglycaemic chemical principle having insulin-triggering and insulin-like behaviors which increases the activity of glucose-6-phosphate dehydrogenase (G6PD) and glucokinase and decreases glucose-6-phosphatase activity, reduce oxidative stress and prevention of glutathione reductase, superoxide dismutase, and catalase activity play a critical role in glucose homeostasis. DK also improve biochemical parameters such as SGPT, SGOT, cholesterol and triglycerides and is found to be safe in animal experiments. The various evidences clearly indicates that DK has definite hypoglycemic potential as well as anti-diabetic activity.

Cochlear Implants and Mobile Wireless Connectivity

2016 ◽  
pp. 65-80
Author(s):  
Panteleimon Chriskos ◽  
Orfeas Tsartsianidis
Keyword(s):  
Cochlear Implants ◽  
Critical Role ◽  
Sensory Systems ◽  
Human Communication ◽  
Mobile Wireless ◽  
The Individual ◽  
Significant Distance ◽  
Wireless Connectivity

Human senses enable humans to perceive and interact with their environment, through a set of sensory systems or organs which are mainly dedicated to each sense. From the five main senses in humans hearing plays a critical role in many aspects of our lives. Hearing allows the perception not only of the immediate visible environment but also parts of the environment that are obstructed from view and/or that are a significant distance from the individual. One of the most important and sometimes overlooked aspects of hearing is communication, since most human communication is accomplished through speech and hearing. Hearing does not only convey speech but also conveys more complex messages in the form of music, singing and storytelling.

SUSTAINABLE DESIGN IN PROJECT DELIVERY: A DISCUSSION ON CURRENT AND FUTURE TRENDS

2016 ◽  
Vol 11 (2) ◽  
pp. 39-56 ◽  
Author(s):  
Karno Widjaja
Keyword(s):  
Construction Projects ◽  
Sustainable Design ◽  
Current System ◽  
Critical Role ◽  
Project Delivery ◽  
Starting Point ◽  
New Construction ◽  
Communication And Coordination ◽  
The Individual ◽  
Sustainability Principles

INTRODUCTION Sustainability principles have become an integral part of the design and construction process for many new construction projects. The selection of the project delivery method (PDM) is extremely important in the effective execution of the project, and plays a critical role in establishing communication and coordination between the key entities: owner, architect, and contractor. The goal of this paper is to hopefully serve as a starting point for further discussion to improve on the AEC industry's current integration of sustainability principles in PDMs. The first step consists of an assessment of current project delivery systems from a sustainable design perspective. This is followed by a determination of the current limitations, and examination of the various disruptions in the industry. Various literature sources are analyzed to form a framework to discuss improvements and optimization strategies beyond the current system. Thereafter, proposed solutions are introduced at both stakeholders, as well as PDM scales. In this paper, the focus for the conducted analysis and proposed methodologies is predicated on new construction projects instead of retrofits due to the resources available. However, the principles can similarly be applied to retrofit scenarios as well, depending on the specific requirements of the individual project at play.

Testing mate recognition through reciprocal crosses of two native populations of the whitefly Bemisia tabaci (Gennadius) in Australia

2019 ◽  
Vol 110 (3) ◽  
pp. 328-339 ◽  
Author(s):  
W. Wongnikong ◽  
S. L. van Brunschot ◽  
J. P. Hereward ◽  
P. J. De Barro ◽  
G. H. Walter
Keyword(s):  
Bemisia Tabaci ◽  
Critical Role ◽  
Mate Recognition ◽  
Distinct Species ◽  
Species Status ◽  
Female Progeny ◽  
Native Populations ◽  
Different Populations ◽  
The Individual ◽  
Mating Tests

AbstractBemisia tabaci (Gennadius) represents a relatively large cryptic species complex. Australia has at least two native populations of B. tabaci sensu lato and these were first found on different host plants in different parts of Australia. The species status of these populations has not been resolved, although their mitochondrial sequences differ by 3.82–4.20%. We addressed the question of whether these AUSI and AUSII B. tabaci populations are distinct species. We used reciprocal cross-mating tests to establish whether the insects from these different populations recognize one another as potential mating partners. The results show that the two native Australian populations of B. tabaci have a mating sequence with four phases, each of which is described. Not all pairs in the control crosses mated and the frequency of mating differed across them. Some pairs in the AUSI-M × AUSII-F did mate (15%) and did produce female progeny, but the frequency was extremely low relative to controls. Microsatellite genotyping of the female progeny produced in the crosses showed these matings were successful. None of the AUSII-M × AUSI-F crosses mated although some of the males did search for females. These results demonstrate the critical role of the mate recognition process and the need to assess this directly in cross-mating tests if the species status of different populations is to be tested realistically. In short, AUSI and AUSII B. tabaci populations are distinct species because the individual males and females do not recognize individuals of the alternative population as potential mating partners.

scholarly journals N-Cadherin Is Critical for the Survival of Germ Cells, the Formation of Steroidogenic Cells, and the Architecture of Developing Mouse Gonads

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1610 ◽  
Author(s):  
Rafal P. Piprek ◽  
Michal Kolasa ◽  
Dagmara Podkowa ◽  
Malgorzata Kloc ◽  
Jacek Z. Kubiak
Keyword(s):  
Germ Cells ◽  
Hormonal Regulation ◽  
Critical Role ◽  
Somatic Cells ◽  
Gonad Development ◽  
Knock Out ◽  
Gonad Differentiation ◽  
Steroidogenic Cells ◽  
The Individual ◽  
And Function

Normal gonad development assures the fertility of the individual. The properly functioning gonads must contain a sufficient number of the viable germ cells, possess a correct architecture and tissue structure, and assure the proper hormonal regulation. This is achieved by the interplay between the germ cells and different types of somatic cells. N-cadherin coded by the Cdh2 gene plays a critical role in this interplay. To gain an insight into the role of N-cadherin in the development of mouse gonads, we used the Cre-loxP system to knock out N-cadherin separately in two cell lines: the SF1+ somatic cells and the OCT4+ germ cells. We observed that N-cadherin plays a key role in the survival of both female and male germ cells. However, the N-cadherin is not necessary for the differentiation of the Sertoli cells or the initiation of the formation of testis cords or ovigerous cords. In the later stages of gonad development, N-cadherin is important for the maintenance of testis cord structure and is required for the formation of steroidogenic cells. In the ovaries, N-cadherin is necessary for the formation of the ovarian follicles. These results indicate that N-cadherin plays a major role in gonad differentiation, structuralization, and function.

scholarly journals Problems of modeling of complex technological systems of greenhouse production

2018 ◽  
Vol 226 ◽  
pp. 02020 ◽  
Author(s):  
Evgeniya P. Klyuchka ◽  
Viktor V. Radin ◽  
Leonid M. Groshev ◽  
Sergey I. Kambulov
Keyword(s):  
Energy Efficiency ◽  
Comparative Analysis ◽  
Optimal Solution ◽  
Technological Systems ◽  
Greenhouse Production ◽  
Technological Paradigm ◽  
Scale Models ◽  
Methodological Approaches ◽  
The Individual ◽  
High Level

The main problems connected with modelling of complex technological systems of greenhouse production are considered. The methodological approaches used at present on the basis of classical comparative analysis with subsequent heuristic conclusions are analysed. Based on the study of this issue, it was concluded that the development and implementation of innovative technologies that affect the individual subsystems of the greenhouse complex do not provide the optimal solution to improve the energy efficiency of the system as a whole. There is a need to create a new synergistic technological paradigm for abandoning costly full-scale models and developing models with a high level of adequacy of real technological processes.

scholarly journals The Pseudomonas aeruginosa PrrF Small RNAs Regulate Iron Homeostasis during Acute Murine Lung Infection

2017 ◽  
Vol 85 (5) ◽  
Author(s):  
Alexandria A. Reinhart ◽  
Angela T. Nguyen ◽  
Luke K. Brewer ◽  
Justin Bevere ◽  
Jace W. Jones ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Small Rnas ◽  
Iron Homeostasis ◽  
Critical Role ◽  
Opportunistic Pathogen ◽  
Lung Infection ◽  
Content Type ◽  
The Individual

ABSTRACT Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that requires iron for virulence. Iron homeostasis is maintained in part by the PrrF1 and PrrF2 small RNAs (sRNAs), which block the expression of iron-containing proteins under iron-depleted conditions. The PrrF sRNAs also promote the production of the Pseudomonas quinolone signal (PQS), a quorum sensing molecule that activates the expression of several virulence genes. The tandem arrangement of the prrF genes allows for expression of a third sRNA, PrrH, which is predicted to regulate gene expression through its unique sequence derived from the prrF1-prrF2 intergenic (IG) sequence (the PrrHIG sequence). Previous studies showed that the prrF locus is required for acute lung infection. However, the individual functions of the PrrF and PrrH sRNAs were not determined. Here, we describe a system for differentiating PrrF and PrrH functions by deleting the PrrHIG sequence [prrF(ΔHIG)]. Our analyses of this construct indicate that the PrrF sRNAs, but not PrrH, are required for acute lung infection by P. aeruginosa. Moreover, we show that the virulence defect of the ΔprrF1-prrF2 mutant is due to decreased bacterial burden during acute lung infection. In vivo analysis of gene expression in lung homogenates shows that PrrF-mediated regulation of genes for iron-containing proteins is disrupted in the ΔprrF1-prrF2 mutant during infection, while the expression of genes that mediate PrrF-regulated PQS production are not affected by prrF deletion in vivo. Combined, these studies demonstrate that regulation of iron utilization plays a critical role in P. aeruginosa's ability to survive during infection.

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