Human Eye Response to Thermal Disturbances

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Maryam Shafahi ◽  
Kambiz Vafai
Keyword(s):  
Thermal Response ◽  
The Body ◽  
Posterior Chamber ◽  
Ambient Conditions ◽  
Human Eye ◽  
Blood Temperature ◽  
Element Simulation ◽  
Porous Media Model ◽  
Dimensional Finite Element

Human eye is one of the most sensitive parts of the body when exposed to a thermal heat flux. Since there is no barrier (such as skin) to protect the eye against the absorption of an external thermal wave, the external flux can readily interact with cornea. The modeling of heat transport through the human eye has been the subject of interest for years, but the application of a porous media model in this field is new. In this study, a comprehensive thermal analysis has been performed on the eye. The iris/sclera section of the eye is modeled as a porous medium. The primary sections of the eye, i.e., cornea, anterior chamber, posterior chamber, iris/sclera, lens, and vitreous are considered in our analysis utilizing a two-dimensional finite element simulation. Four different models are utilized to evaluate the eye thermal response to external and internal disturbances. Results are shown in terms of temperature profiles along the pupillary axis. Effects of extreme ambient conditions, blood temperature, blood convection coefficient, ambient temperature, sclera porosity, and perfusion rate on different regions of the eye are investigated. Furthermore, the role of primary thermal transport mechanisms on the eye subject to different conditions is analyzed.

Influence of Exercise Condition on Tissue Blood Temperature Using Whole Body Model

2013 ◽  
Author(s):  
Swarup A. Zachariah ◽  
Anup K. Paul ◽  
Rupak K. Banerjee ◽  
Liang Zhu
Keyword(s):  
Human Body ◽  
Core Body Temperature ◽  
Thermal Response ◽  
The Body ◽  
Tissue Temperature ◽  
Whole Body ◽  
Transfer Model ◽  
Blood Temperature ◽  
Exercise Condition ◽  
Core Body

Predicting thermal responses of the human body accurately during different exercise conditions is of increasing importance. Computing changes in the core body temperature (T c) during exercise require detailed modeling of both the body tissue temperature and the time-dependent blood temperature. Predicting changes in T c is challenging because the model needs to respond effectively to the changes in perfusion or sweating. Our study was to demonstrate the ability of a recently developed whole body heat transfer model. It simulates the tissue-blood interaction to predict the thermal response of the human body under different exercise intensities. The cases simulated were of a human being walking on a treadmill at 0.9, 1.2 and 1.8 m/s for 30 minutes. It was shown that T c was effectively regulated within 0.17 °C of the steady state value of 37.23 °C for the three cases by means of adjusting the cardiac output; varying between 15 to 25 liters per minute.

Thermal Modeling of the Human Eye as a Porous Structure

2009 ◽  
Author(s):  
Maryam Shafahi ◽  
Kambiz Vafai
Keyword(s):  
Blood Flow ◽  
Thermal Equilibrium ◽  
Radiation Effects ◽  
Energy Transport ◽  
Thermal Modeling ◽  
The Body ◽  
Local Thermal Equilibrium ◽  
Posterior Chamber ◽  
Convection Coefficient ◽  
Human Eye

Human eye is one of the most sensitive parts of the body when exposed to radiation effects. Since there is no barrier (such as skin) to protect the eye against the absorption of the external thermal waves, radiation can readily interact with cornea. On the other hand, lack of blood flow in the interior part of the eye makes it more vulnerable compared to other organs even in the case of weak heat interaction. Further, blood flow circulation alone cannot establish thermal equilibrium between the eye and body organs effectively. There are limitations in measuring human eye temperature profile experimentally due to the required invasive procedures in monitoring the inner layers. Therefore, there is a need to develop an accurate model to represent the eye structure and energy transport through it. Thermal modeling of the eye is important to investigate the effect of external heat sources as well as in predicting the abnormalities within the eye. Modeling of heat transport through the human eye has been the subject of interest for years, but the application of porous media models in this field is new and will be one of the themes of this study. In this work, iris/sclear is considered as a porous medium and energy transport is modeled using the tissue local thermal equilibrium equations. The eye is assumed to include six different parts: cornea, anterior chamber, posterior chamber, iris/sclera, lens and vitreous. A two-dimensional finite element simulation will be performed. Results are shown in terms of transient corneal surface temperature, isothermal lines in different regions and local temperature of pupillary axis. Effects of external radiation sources, convection coefficient of the surrounding air, blood temperature, blood convection coefficient and ambient temperature on different regions of the eye are also investigated.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

The Role of Computer Modeling in Electrocardiography

1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom
Keyword(s):  
Electrical Activity ◽  
Computer Modeling ◽  
Body Surface ◽  
Electrical Current ◽  
The Body ◽  
Volume Conductor ◽  
Current Generator ◽  
Cardiac Electrical Activity ◽  
Source Models

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.

Questions on the role of biofilms for the adaptation of microorganisms to unfavorable environmental factors by the example of P. aeruginosa

2020 ◽  
Vol 99 (4) ◽  
pp. 379-383
Author(s):  
Vasily N. Afonyushkin ◽  
N. A. Donchenko ◽  
Ju. N. Kozlova ◽  
N. A. Davidova ◽  
V. Yu. Koptev ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Environmental Factors ◽  
Barrier Function ◽  
Infectious Agent ◽  
Antagonistic Activity ◽  
The Body ◽  
Main Function ◽  
Pathogenic Potential ◽  
The Face

Pseudomonas aeruginosa is a widely represented species of bacteria possessing of a pathogenic potential. This infectious agent is causing wound infections, fibrotic cystitis, fibrosing pneumonia, bacterial sepsis, etc. The microorganism is highly resistant to antiseptics, disinfectants, immune system responses of the body. The responses of a quorum sense of this kind of bacteria ensure the inclusion of many pathogenicity factors. The analysis of the scientific literature made it possible to formulate four questions concerning the role of biofilms for the adaptation of P. aeruginosa to adverse environmental factors: Is another person appears to be predominantly of a source an etiological agent or the source of P. aeruginosa infection in the environment? Does the formation of biofilms influence on the antibiotic resistance? How the antagonistic activity of microorganisms is realized in biofilm form? What is the main function of biofilms in the functioning of bacteria? A hypothesis has been put forward the effect of biofilms on the increase of antibiotic resistance of bacteria and, in particular, P. aeruginosa to be secondary in charcter. It is more likely a biofilmboth to fulfill the function of storing nutrients and provide topical competition in the face of food scarcity. In connection with the incompatibility of the molecular radii of most antibiotics and pores in biofilm, biofilm is doubtful to be capable of performing a barrier function for protecting against antibiotics. However, with respect to antibodies and immunocompetent cells, the barrier function is beyond doubt. The biofilm is more likely to fulfill the function of storing nutrients and providing topical competition in conditions of scarcity of food resources.

Receptions of the Past: Commemoration, Racism, Desire

Somatechnics ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 288-303
Author(s):  
Michael Connors Jackman
Keyword(s):  
Critical Point ◽  
Social Relations ◽  
White Privilege ◽  
Body Politic ◽  
The Body ◽  
Race And Racism ◽  
Lesbian And Gay ◽  
The Past ◽  
History Of

This article investigates the ways in which the work of The Body Politic (TBP), the first major lesbian and gay newspaper in Canada, comes to be commemorated in queer publics and how it figures in the memories of those who were involved in producing the paper. In revisiting a critical point in the history of TBP from 1985 when controversy erupted over race and racism within the editorial collective, this discussion considers the role of memory in the reproduction of whiteness and in the rupture of standard narratives about the past. As the controversy continues to haunt contemporary queer activism in Canada, the productive work of memory must be considered an essential aspect of how, when and for what reasons the work of TBP comes to be commemorated. By revisiting the events of 1985 and by sifting through interviews with individuals who contributed to the work of TBP, this article complicates the narrative of TBP as a bluntly racist endeavour whilst questioning the white privilege and racially-charged demands that undergird its commemoration. The work of producing and preserving queer history is a vital means of challenging the intentional and strategic erasure of queer existence, but those who engage in such efforts must remain attentive to the unequal terrain of social relations within which remembering forms its objects.

A Good Sentencing Precedent is Hard to Find

2020 ◽  
Vol 32 (3) ◽  
pp. 138-144
Author(s):  
Brian A. Jacobs
Keyword(s):  
United States ◽  
Significant Role ◽  
College Admissions ◽  
The Body ◽  
Federal Law ◽  
Criminal Cases ◽  
Federal Sentencing

In federal criminal cases, federal law requires that judges consider the sentences other courts have imposed in factually similar matters. Courts and parties, however, face significant challenges in finding applicable sentencing precedents because judges do not typically issue written sentencing opinions, and transcripts of sentencings are not readily available in advanced searchable databases. At the same time, particularly since the Supreme Court’s 2005 decision in United States v. Booker, sentencing precedent has come to play a significant role in federal sentencing proceedings. By way of example, this article discusses recent cases involving defendants with gambling addictions, and recent cases involving college admissions or testing fraud. The article explores the ways the parties in those cases have used sentencing precedent in their advocacy, as well as the ways the courts involved have used sentencing precedent to justify their decisions. Given the important role of sentencing precedent in federal criminal cases, the article finally looks at ways in which the body of sentencing law could be made more readily available to parties and courts alike.

Putting the Madhyamaka Trick in Context: A Contextualist Reading of Huntington’s Interpretation of Madhyamaka

2014 ◽  
Vol 31 (1) ◽  
pp. 91-124
Author(s):  
Michael Dorfman
Keyword(s):  
Fifteenth Century ◽  
Common Ground ◽  
Correspondence Theory ◽  
The Body ◽  
Rational Analysis ◽  
At Command ◽  
Rational Argumentation ◽  
Logical Fallacies ◽  
Key Terms

In a series of works published over a period of twenty five years, C.W. Huntington, Jr. has developed a provocative and radical reading of Madhyamaka (particularly Early Indian Madhyamaka) inspired by ‘the insights of post- Wittgensteinian pragmatism and deconstruction’ (1993, 9). This article examines the body of Huntington’s work through the filter of his seminal 2007 publication, ‘The Nature of the M?dhyamika Trick’, a polemic aimed at a quartet of other recent commentators on Madhyamaka (Robinson, Hayes, Tillemans and Garfield) who attempt ‘to read N?g?rjuna through the lens of modern symbolic logic’ (2007, 103), a project which is the ‘end result of a long and complex scholastic enterprise … [which] can be traced backwards from contemporary academic discourse to fifteenth century Tibet, and from there into India’ (2007, 111) and which Huntington sees as distorting the Madhyamaka project which was not aimed at ‘command[ing] assent to a set of rationally grounded doctrines, tenets, or true conclusions’ (2007, 129). This article begins by explicating some disparate strands found in Huntington’s work, which I connect under a radicalized notion of ‘context’. These strands consist of a contextualist/pragmatic theory of truth (as opposed to a correspondence theory of truth), a contextualist epistemology (as opposed to one relying on foundationalist epistemic warrants), and a contextualist ontology where entities are viewed as necessarily relational (as opposed to possessing a context-independent essence.) I then use these linked theories to find fault with Huntington’s own readings of Candrak?rti and N?g?rjuna, arguing that Huntington misreads the semantic context of certain key terms (tarka, d???i, pak?a and pratijñ?) and fails to follow the implications of N?g?rjuna and Candrak?rti’s reliance on the role of the pram??as in constituting conventional reality. Thus, I find that Huntington’s imputation of a rejection of logic and rational argumentation to N?g?rjuna and Candrak?rti is unwarranted. Finally, I offer alternate readings of the four contemporary commentators selected by Huntington, using the conceptual apparatus developed earlier to dismiss Robinson’s and Hayes’s view of N?g?rjuna as a charlatan relying on logical fallacies, and to find common ground between Huntington’s project and the view of N?g?rjuna developed by Tillemans and Garfield as a thinker committed using reason to reach, through rational analysis, ‘the limits of thought.’

Ghrelin and Obesity-An Update

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Gandhi M. ◽  
Swaminathan S.
Keyword(s):  
Diabetes Mellitus ◽  
Cardiac Output ◽  
Energy Balance ◽  
Vascular Resistance ◽  
The Body ◽  
Ghrelin Receptor ◽  
Type2 Diabetes ◽  
Type2 Diabetes Mellitus ◽  
Natural Hormones

Ghrelin as human natural hormones is involved in fundamental regulatory process of eating and energy balance. It is a stomach derived hormone that acts as at the ghrelin receptor in multiple tissues throughout to the body. Its properties includes increasing appetite, decreasing systemic inflammation, decreasing vascular resistance ,increasing cardiac output, increasing glucose and IGF-1 levels, Hence it may play a significant role in Diabetes mellitus. Many studies have linked ghrelin to obesity and this paper is an attempt to bring out recent findings on the role of ghrelin in Diabetes Mellitus, particularly type2 Diabetes mellitus.

Effectiveness Of Toilet Training Education On Mother's Behavior And Toddler Age Toilet Training Ability (18-36 Months)

2020 ◽  
Vol 5 (2) ◽  
pp. 49-55
Author(s):  
Hafiko Andresni ◽  
Zahtamal Zahtamal ◽  
Winda Septiani ◽  
Mitra Mitra ◽  
Lita Lita
Keyword(s):  
Sampling Technique ◽  
T Test ◽  
The Body ◽  
Toilet Training ◽  
Wilcoxon Test ◽  
Control Group ◽  
Maternal Knowledge ◽  
Control Group Design ◽  
Significant Difference

ABSTRACT Toilet training is an effort to train children to be able to control and urinate (BAK) and defecate (BAB). Toilet training is one of the main tasks of children at toddler age. Toilet training is one of the main tasks of children in toddler age which is very important to be done to create independence in children in controlling BAK and BAB and children know the parts of the body and their functions. Data in 2012 shows that ± 60% of parents do not teach toilet training to children from an early age. The aim of the study was to find out the effectiveness of toilet training education on maternal behavior and toilet skills in toddler age training (18-36 months). The study was conducted in July-August 2018. This type of quantitative research used the design of the Quasy pretest and posttest experiment with non-equivalent control group design. Samples were 36 mothers and 36 children with purposive sampling technique. Data analysis used Paired t test, Wilcoxon test, Man-Whitney test an Independent t test. The results showed that toilet training education through lecture methods, modules and maze games was more effective than toilet training education through lecture and leaflet methods on children's knowledge and abilities. Conversely, for the role of mothers in supervision there is no significant difference in effectiveness. Health education is recommended in health promotion programs to increase maternal knowledge, the role of mothers and the ability of toilet training children independently. Keywords: Toilet training, Lecture method, Module, Maze game, Leaflet, Knowledge, Role of mother, Children's ability.

Sign in / Sign up

Export Citation Format

Share Document