Dynamical behavior of cardiac conduction system under external disturbances: simulation based on microcontroller technology

The heart rhythm is one of the most interesting aspects of the dynamic behavior of biological systems. Understanding heart rhythms is essential in the dynamic analysis of the heart. Each type of dynamic behaviour can describe normal or pathological physiology. The heart is made up of nodes ranging from SA node (natural pacemaker) to Purkinje fibers. The electric current originates in the sinus node and travels through the heart until it reaches the Purkinje fibers, causing after its passage through each of the nodes a heartbeat thus constituting the electrocardiogram (ECG). Since the origin of the electric current is the sinus node, in this article we study numerically and experimentally by microcontroller the influence of the sinus node on the propagation of electric current through the heart. A study of the sinus node in its autonomous state shows us that in their coupled state, the nodes of the heart qualitatively reproduce the time series of the action potential of this latter, which leads to the recording of the ECG. A study when the sinus node is subjected to periodic pulsed excitation E 1(t) = kP(t), assumed to come from blood pressure, with P(t) the blood pressure, shows that for some selected frequencies, it is found that the nodes of the heart and the ECG exhibit responses having the same shape and the same frequencies as those of the pulsatile blood pressure. This suggests the possibility of using such a conversion and excitation mechanism to replicate the functioning of cardiac conduction system. The chaotic analysis of the sinus node subjected to a sinusoidal type disturbance (E 0sin(ωt)) is also presented, it shows that in its chaotic state, the nodes of the heart, as well as the ECG, provide very high frequency signals. This requires the control of the sinus node (natural pacemaker) in such a situation

The Law of Entropy Increase and the Meissner Effect

The law of entropy increase postulates the existence of irreversible processes in physics: the total entropy of an isolated system can increase, but cannot decrease. The annihilation of an electric current in normal metal with the generation of Joule heat because of a non-zero resistance is a well-known example of an irreversible process. The persistent current, an undamped electric current observed in a superconductor, annihilates after the transition into the normal state. Therefore, this transition was considered as an irreversible thermodynamic process before 1933. However, if this transition is irreversible, then the Meissner effect discovered in 1933 is experimental evidence of a process reverse to the irreversible process. Belief in the law of entropy increase forced physicists to change their understanding of the superconducting transition, which is considered a phase transition after 1933. This change has resulted to the internal inconsistency of the conventional theory of superconductivity, which is created within the framework of reversible thermodynamics, but predicts Joule heating. The persistent current annihilates after the transition into the normal state with the generation of Joule heat and reappears during the return to the superconducting state according to this theory and contrary to the law of entropy increase. The success of the conventional theory of superconductivity forces us to consider the validity of belief in the law of entropy increase.

Gradual Technology Development for Ethnic Groups

This chapter presents the application of the concept of gradual technology to improve and increase the productivity of a workshop for the manufacture of handcrafted furniture owned by a cooperative formed by members of the Guarijía ethnic group, located in San Bernardo, Alamos, Sonora. The production process of the rustic furniture called “stool” was systematized and equipment was designed taking into account basic ergonomic aspects. Production sub-processes of the workshop and equipment were improved, including machinery design, purchase of basic technology, adaptation of electric current, water, and air conditioning systems. The basic inputs for manufacturing the furniture, such as wood and cowhide, were studied to determine whether the production of the stool affected the environment. The operating personnel in charge of the cooperative were trained in the use of the equipment and in the visualization of the improved processes.

An Embedded Based Electric Shock Prevention for Human Safety

An electric shock is the effect of passing an electric current through the body. The minimum current a human can feel is thought to be about 1 milliampere (mA). The effect can range from minor tingling to muscle spasms, tissue damage, fibrillation of the heart, loss of consciousness, and even death. These effects depend on a variety of factors, including the strength of the current, duration of the current, the area of the body through which the current passes, and whether the person is grounded or insulated from the ground. Death caused by an electric shock is referred to as electrocution.

Piezoelectric Configuration for Generating Electricity Using Waves Power

This study is aimed at determining the piezoelectric configuration for generating electricity from wave power through the design of a prototype model named Cov-TOTal. The study was carried out in Tomini Bay, Lopo Village, Batudaa Pantai District, Gorontalo Regency, located at approximately ±50 meters from the shoreline, while the piezoelectric construction was arranged in parallel with varying numbers of 28, 70, and 90 pieces. The result showed that the amount of piezoelectric configuration affects the value of the voltage and electric current generated by the Cov-TOTal model. Furthermore, the average electric voltage values were 17.58, 20.76, and 29.85 volts, while the average current was 1.16, 1.73, and 2.01 mA for each piezoelectric amount. Therefore, the largest values of power and electrical energy for each piezoelectric are 16.65 mW and 0.56 joules, 31.82 mW and 1.20 joules, and 44.59 mW and 1.77 joules, respectively. This study concluded that the amount of piezoelectric configuration has a significant effect on the voltage, current, power, and electrical energy produced.