scholarly journals Effects of Maximal Sodium and Potassium Conductance on the Stability of Hodgkin-Huxley Model

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yue Zhang ◽  
Kuanquan Wang ◽  
Yongfeng Yuan ◽  
Dong Sui ◽  
Henggui Zhang

Hodgkin-Huxley (HH) equation is the first cell computing model in the world and pioneered the use of model to study electrophysiological problems. The model consists of four differential equations which are based on the experimental data of ion channels. Maximal conductance is an important characteristic of different channels. In this study, mathematical method is used to investigate the importance of maximal sodium conductanceg-Naand maximal potassium conductanceg-K. Applying stability theory, and takingg-Naandg-Kas variables, we analyze the stability and bifurcations of the model. Bifurcations are found when the variables change, and bifurcation points and boundary are also calculated. There is only one bifurcation point wheng-Nais the variable, while there are two points wheng-Kis variable. The (g-Na,  g-K) plane is partitioned into two regions and the upper bifurcation boundary is similar to a line when bothg-Naandg-Kare variables. Numerical simulations illustrate the validity of the analysis. The results obtained could be helpful in studying relevant diseases caused by maximal conductance anomaly.

2019 ◽  
Vol 10 (1) ◽  
pp. 119-124
Author(s):  
Olatunji Abdul Shobande ◽  
Kingsley Chinonso Mark

Abstract The quest for urgent solution to resolve the world liquidity problem has continued to generate enthusiastic debates among political economists, policy makers and the academia. The argument has focused on whether the World Bank Group was established to enhance the stability of international financial system or meant to enrich the developed nations. This study argues that the existing political interest of the World Bank Group in Africa may serve as lesson learned to other ambitious African Monetary Union.


Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 8
Author(s):  
Pyrrhon Amathes ◽  
Paul Christodoulides

Photography can be used for pleasure and art but can also be used in many disciplines of science, because it captures the details of the moment and can serve as a proving tool due to the information it preserves. During the period of the Apollo program (1969 to 1972), the National Aeronautics and Space Administration (NASA) successfully landed humans on the Moon and showed hundreds of photos to the world presenting the travel and landings. This paper uses computer simulations and geometry to examine the authenticity of one such photo, namely Apollo 17 photo GPN-2000-00113. In addition, a novel approach is employed by creating an experimental scene to illustrate details and provide measurements. The crucial factors on which the geometrical analysis relies are locked in the photograph and are: (a) the apparent position of the Earth relative to the illustrated flag and (b) the point to which the shadow of the astronaut taking the photo reaches, in relation to the flagpole. The analysis and experimental data show geometrical and time mismatches, proving that the photo is a composite.


2021 ◽  
pp. 1-25
Author(s):  
Jorg Kustermans ◽  
Rikkert Horemans

Abstract There is increasing agreement that states and other political actors on the world stage sometimes achieve international authority. However, there is less agreement about the nature and functioning of international authority relations. What determines whether an actor will be recognized as an authoritative actor? And what are the effects thereof? In this essay, we identify four distinct conceptions of authority in the study of international relations: authority as contract, authority as domination, authority as impression, and authority as consecration. Consideration of the typology leads to two important insights. First, the phenomenon of authority has an essentially experiential dimension. Subordinate actors’ emotional experience of authority determines their response to authority and thus also has a fundamental impact on the stability of authority. Second, the emergence of forms of international authority does not entail, at least not necessarily, the weakening of the sovereignty of states, but can equally be argued to strengthen it.


Author(s):  
Denis R Jury ◽  
Donald J Mikkelsen ◽  
Deborah Glen ◽  
Peter J. Dunn

We have evaluated a semi-quantitative dry immunochemical screening method (Micral-Test) for the detection of low concentrations of albumin in urine. The stability of Micral-Test strips on storage was good, especially with regard to temperature, light and humidity. Changes in urine osmolality (urea and creatinine concentration), pH and sodium and potassium concentration did not have a significant analytical effect on the Micral-Test measurement; extremes of temperature altered the rate of colour development. The depth of dipping the strip into the sample and the timing of reading colour development were critical. We measured the albumin concentration in 184 urine samples from diabetic outpatients by the Micral-Test and by our in-house immunoturbidimetric method; a Micral-Test result of 20 mg/L had a sensitivity of 91% and specificity of 97% to predict a discriminating urine albumin concentration > 30 mg/L by the in house method. The Micral-Test is suitable for use by non-laboratory personnel and is capable of producing analytically acceptable results for use in diabetes clinics and by general practitioners.


1975 ◽  
Vol 42 (3) ◽  
pp. 552-556 ◽  
Author(s):  
A. J. Padgaonkar ◽  
K. W. Krieger ◽  
A. I. King

The computation of angular acceleration of a rigid body from measured linear accelerations is a simple procedure, based on well-known kinematic principles. It can be shown that, in theory, a minimum of six linear accelerometers are required for a complete definition of the kinematics of a rigid body. However, recent attempts in impact biomechanics to determine general three-dimensional motion of body segments were unsuccessful when only six accelerometers were used. This paper demonstrates the cause for this inconsistency between theory and practice and specifies the conditions under which the method fails. In addition, an alternate method based on a special nine-accelerometer configuration is proposed. The stability and superiority of this approach are shown by the use of hypothetical as well as experimental data.


Author(s):  
Rafail R. Mukhametzyanov ◽  
◽  
Nikolay G. Platonovskiy ◽  
Akhmed M. Khezhev ◽  
Tatiyana V. Ostapchuk ◽  
...  

In the context of the modern global financial world order, an important element of the stability of the national monetary unit of the overwhelming majority of countries in the world, especially developing countries, is foreign exchange earnings. For some countries with favorable natural and climatic conditions, the production, processing and export of agricultural products plays a significant role in the overall structure of foreign exchange earnings in the country. The constantly increasing demand from consumers for fruits, berries, nuts and their processed products allows economic entities of national fruit and berry subcomplexes to increase the volume of growing and exporting these types of products. This study analyzes the change in the volume of exports and imports of fruit and berry products in value terms for the period 2010-2019. It is revealed that some states, being the largest exporters of fruits, berries, nuts and products of their processing, occupy significant positions in the import of these types of products from abroad. Based on the author’s calculations, the top 30 countries of the world have been compiled in terms of net foreign exchange earnings from international trade in this type of product. According to this indicator, the first line with a level of $ 7.506 billion was occupied by Spain, while it increased it by $ 1.675 billion over 10 years. As for Russia, despite the counter-sanctions against the countries of the European Union and some other countries of the world, as well as the ongoing policy of import substitution, including in domestic gardening, it continues to be one of the main importers of fruits, berries, nuts and their processing products in the world. Thus, our country supports both foreign producers and other commercial structures that carry out the processes of commodity circulation of fruit and berry products, and the receipt of foreign exchange earnings in these powers.


2020 ◽  
Vol 2 (2) ◽  
pp. 84-89
Author(s):  
Tati Maryati

The Corona virus or Covid-19 which is unexpected will come to us, has an impact on health, economy and also humanity throughout the world and is able to fundamentally change the world. Supplements are disrupted because production is stopped, retail stores close, causing consumers to change their behavior, which had previously gone offline shopping. Not just shopping, when a pandemic, the way of thinking becomes different. Consumers around the world are looking for products and brands through new ways and new habits are formed. Online transactions focus more on basic products to make ends meet. The fact that Covid-19's anti-virus has not been found raises concerns about disrupted health and the Government's regulation to work and stay at home also raises concerns about disrupted businesses. Differences from habits and interests or preferences that are different for each person, provide different responses to the problems faced and solutions for the future. The habit of shopping offline has a tendency to continue for complementary products while food products are more directed towards offline. The rest eating habits at home can be continued because it provides more hygiene guarantees. The new habit of holding online meetings with distant relatives or colleagues will be increasingly considered given the many more positive things that can be obtained. Likewise with work problems, working from home is more interesting to consider because it is more efficient and effective and the results can be more productive. This new consumer behavior is adjusted to provide satisfaction for many parties, with the assistance of institutions or governments that oversee the security of supply and demand and maintain the stability of both. 


2016 ◽  
Vol 8 (3) ◽  
pp. 5
Author(s):  
Jirí Stavek

<p class="1Body">An attempt is presented for the description of the spectral colors using the standard trigonometric tools in order to extract more information about photons. We have arranged the spectral colors on an arc of the circle with the radius R = 1 and the central angle θ = π/3 when we have defined cos (θ) = λ<sub>380</sub>/λ<sub>760</sub> = 0.5. Several trigonometric operations were applied in order to find the gravity centers for the scotopic, photopic, and mesopic visions. The concept of the center of gravity of colors introduced Isaac Newton. We have postulated properties of the long-lived photons with the new interpretation of the Hubble (Zwicky-Nernst) constant H<sub>0</sub> = 2.748… * 10<sup>-18</sup> kg kg<sup>-1 </sup>s<sup>-1</sup>, the specific mass evaporation rate (SMER) of gravitons from the source mass. The stability of international prototypes of kilogram has been regularly checked. We predict that those standard kilograms due to the evaporation of gravitons lost 8.67 μg kg<sup>-1</sup> century<sup>-1</sup>. The energy of long-lived photons was trigonometrically decomposed into three parts that could be experimentally tested: longitudinal energy, transverse energy and energy of evaporated gravitons. We tested the properties of the long-lived photons with the experimental data published for the best available standard candles: supernovae Type Ia. There was found a surprising match of those experimental data with the model of the long-lived photons. Finally, we have proposed a possible decomposition of the big G (Newtonian gravitational constant) and the small kappa κ (Einsteinian gravitational constant) in order to get a new insight into the mysterious gravitational force and/or the curvature concept.</p>


2016 ◽  
Vol 858 ◽  
pp. 300-304
Author(s):  
Zhen Fu Chen ◽  
Dan Wu ◽  
Qiu Wang Tao ◽  
Yuan Chu Gan

The high temperature stability of AC-16, AC-13, AC-20 under specimen thickness of 5cm and 6cm is studied through indoor asphalt mixture high rutting test, Through comparison and analysis about experimental data, it is found that the stability of AC-16, AC-13, AC-20 asphalt mixture at high- temperature decreases in turn. It is shown that thickness changes did not affect the change trend of the high temperature stability under gradation change, and the stability of AC-16 at high-temperature is the best, the AC-13 is second and the AC-20 is less.


2009 ◽  
Vol 23 (11) ◽  
pp. 2503-2509 ◽  
Author(s):  
S. K. SHARMA

The present paper proposes a computing model for temperature dependence of volume thermal expansivity, volume expansion ratio and second order temperature derivative of volume based on the assumption that the product αKT remains constant at high temperatures and zero pressure. We have taken NaCl and KCl to testify the validity of the present model. A fairly close agreement between the calculated results and experimental data strongly supports the present model.


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