A Theoretical Analysis of One-Dimensional Nonsteady Muscular Contraction

1974 ◽  
Vol 41 (2) ◽  
pp. 327-331 ◽  
Author(s):  
John A. Steen ◽  
H. H. Chiu ◽  
Augusto H. Moreno
Keyword(s):  
Three Dimensional ◽  
Muscular Contraction ◽  
Irreversible Thermodynamics ◽  
Physical Parameters ◽  
Specific Information ◽  
Contractile State ◽  
One Dimensional ◽  
Internal Function ◽  
Dimensional Element ◽  
General Physical

Most of the existing theories of muscle contraction rely primarily on specific information of the internal function of the system. These theories are generally based on mechanics or chemical kinetics models. We have previously proposed a general theory based on the laws of irreversible thermodynamics that requires only a general knowledge of the physical system. The theory has been derived in a form that is applicable to the three-dimensional, nonuniform, unsteady contraction of muscle. With a knowledge of the general physical parameters of the system, the solution of the equations would specify the force and shortening at each point in the muscle as a function of space and time. So far, we have solved the specific problem of the overall contraction of a uniform element of contractile material constrained to contract isometrically [1]. Presented herein is the response within a one-dimensional element of muscle rigidly attached at one end and acted upon by a sinusoidal force at the other end. The solution indicates that force and shortening within the muscle are composed mathematically of two sinusoidal waves moving in opposite directions. It is also seen that the maximum absolute value of the transfer function (from force to shortening) corresponds to an optimum physiological condition, where the passive elastic and active contractile responses combine to produce maximum work output. This suggests that a muscle at its optimum contractile state will shorten, against the same external force, a greater amount than when it was at a different contractile state. Application of the scheme of analysis to general nonsteady contractions of muscle, including the myocardium, is also indicated.

Transport Processes in Magnetosolidmechanics

1966 ◽  
Vol 33 (4) ◽  
pp. 770-776 ◽  
Author(s):  
M. R. El-Saden ◽  
O. A. Arnas
Keyword(s):  
Three Dimensional ◽  
Second Law Of Thermodynamics ◽  
Irreversible Thermodynamics ◽  
Transport Processes ◽  
Governing Equations ◽  
Electrical Currents ◽  
One Dimensional ◽  
Current Densities ◽  
Galvanomagnetic Effects ◽  
State Case

Consideration is given to the problem of a solid conducting heat and electrical currents in the presence of externally applied magnetic fields. Interactions due to the thermoelectric, thermomagnetic, and galvanomagnetic effects are taken into consideration. The general three-dimensional governing equations are established. The generalized Ohm’s law and Fourier’s law of heat conduction as formulated by the methods of nonequilibrium (irreversible) thermodynamics are employed. The governing equations are used for the analysis of a one-dimensional steady-state case, assuming constant thermophysical properties. The variations of temperature, electric field, magnetic field, and electric and thermal current densities are presented analytically and graphically. The second law of thermodynamics imposes certain limitations on the validity of the results. These limitations are discussed in detail.

Conformation Control of DNA Molecules by Means Geometric and Physical Parameters

2019 ◽  
Vol 20 (9) ◽  
pp. 550-559
Author(s):  
A. A. Ilyukhin ◽  
D. V. Timoshenko
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Interatomic Interaction ◽  
Theory Of Elasticity ◽  
Physical Parameters ◽  
Dimensional Problem ◽  
Dna Molecules ◽  
Conceptual Approach ◽  
Deformable Solid ◽  
One Dimensional

A conceptual approach to the problem of managing spatial configurations of DNA molecules is considered. The work is problematic in nature and is a synthesis of the authors’ research in the field of modeling the behavior and structure of DNA by the methods of the mechanics of a deformable solid. The subject of research in this paper is the question of the applicability of methods of control theory to a living object by the example of a DNA molecule. The paper considers both issues of controllability on examples of the influence of the parameters of a molecule on its configuration, and questions of observability and identification of parameters of a molecule, based on the visible configuration in the natural environment. A brief review of the authors’ results in terms of adaptation to the objects of research of existing and development of new mathematical models of deformable elastic objects with regard to their internal structure is given. The proposed approach is based on the concept of transition using known methods of molecular dynamics from a multi-element discrete medium to a continuum containing momentary stresses. To this end, in previous works, the authors obtained the dependence of the components of the strain tensors, force and moment stresses on various types of interatomic interaction potentials (LennardJones potential, Born-Meyer potential, etc.). The need to choose as the base model of a continuum containing momentary stresses is dictated by the peculiarities of the main object of study - nucleic acid molecules and biopolymers - which have several degrees of freedom of rotational motions. Also, as an example, we consider the case for which the reduction from the three-dimensional problem of the asymmetric theory of elasticity to a one-dimensional one was carried out by splitting the three-dimensional problem into a set of two-dimensional and one-dimensional problems. The kinematic parameters that are necessary to attract in order to obtain a closed system of equations of the one-dimensional moment theory of rods with the system of Kirchhoff’s differential equations are indicated. The remaining geometrical values are found from the relations defining them. The proposed approach is consistent with current trends in the field of molecular modeling in biophysics and physico-chemical biology, and it seems promising in solving the problems of controlling genetic and biochemical processes involving DNA.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Electron Microscopy in the Study of Natural Phytoplankton Assemblages

1985 ◽  
Vol 43 ◽  
pp. 620-623
Author(s):  
Linda Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Aquatic Environment ◽  
Size Range ◽  
Physical Parameters ◽  
Specific Information ◽  
Phytoplankton Assemblages ◽  
Phytoplankton Productivity ◽  
Ecosystem Effects ◽  
Time Of Year ◽  
Species Specific

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

scholarly journals Elastic transformation of histological slices allows precise co-registration with microCT data sets for a refined virtual histology approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jonas Albers ◽  
Angelika Svetlove ◽  
Justus Alves ◽  
Alexander Kraupner ◽  
Francesca di Lillo ◽  
...  
Keyword(s):  
Three Dimensional ◽  
High Specificity ◽  
Histopathological Analysis ◽  
Specific Information ◽  
Data Sets ◽  
Virtual Histology ◽  
Novel Approach ◽  
Cell Tissue ◽  
Immuno Histochemistry ◽  
3D Information

AbstractAlthough X-ray based 3D virtual histology is an emerging tool for the analysis of biological tissue, it falls short in terms of specificity when compared to conventional histology. Thus, the aim was to establish a novel approach that combines 3D information provided by microCT with high specificity that only (immuno-)histochemistry can offer. For this purpose, we developed a software frontend, which utilises an elastic transformation technique to accurately co-register various histological and immunohistochemical stainings with free propagation phase contrast synchrotron radiation microCT. We demonstrate that the precision of the overlay of both imaging modalities is significantly improved by performing our elastic registration workflow, as evidenced by calculation of the displacement index. To illustrate the need for an elastic co-registration approach we examined specimens from a mouse model of breast cancer with injected metal-based nanoparticles. Using the elastic transformation pipeline, we were able to co-localise the nanoparticles to specifically stained cells or tissue structures into their three-dimensional anatomical context. Additionally, we performed a semi-automated tissue structure and cell classification. This workflow provides new insights on histopathological analysis by combining CT specific three-dimensional information with cell/tissue specific information provided by classical histology.

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