Abstract: The number of biomedical studies where the observed effects are determined by the laws of quantum physics is constantly growing. These include respiration, vision, smell, photosynthesis, mutations, etc., united by name "quantum biology". The effect on organisms of magnetic fields, including those weakened in comparison with the geomagnetic field, is one of such studies. The magnetic field can act only on magnetic moments, the most important representative of which is the electron. The magnetic field changes the quantum dynamics of electrons in the body, which ultimately leads to the observed reactions at the biochemical and behavioral levels. Organisms on Earth have evolved in a geomagnetic field, which means that its absence can cause disturbances in the normal functioning of organisms. Indeed, there are more than two hundred scientific publications on this topic. Today, it has been reliably established that the hypomagnetic field can change the functioning of organisms from bacteria and fungi to mammals and humans. In deep space flight and in future missions to the Moon and Mars, astronauts will be in a hypomagnetic field, which is less than a natural geomagnetic field by more than a hundred times. Such a weakening of the magnetic field is associated with an additional risk. This mini review provides initial information about the levels of the magnetic field on Earth, in near and distant outer space, and on the surfaces of the Moon and Mars. Information is provided on the hypomagnetic field effects on the human body and about the mechanisms of such effects. It is reported about the features of research in magnetobiology that require special statistical methods for processing the results. The complexity of creating a hypomagnetic field in volumes sufficient to accommodate the human body is discussed. The primary tasks in this relatively new research field are formulated.

Keywords: animal magnetic navigation, radical pair mechanism, magnetobiology, organism, cosmos, interplanetary magnetic field, hypomagnetic field, geomagnetic field, human, magnetic biological effects

Abstract: The chemoreflex control of breathing plays a major role in human lung ventilation adjustment in response to metabolic demands and CO2, O2 partial pressure changes in the inhaled air. The extreme conditions, e.g. emergency work in mines or deep-sea diving, space flights, can change the respiratory system reaction to CO2 and O2. The study of the relevant respiratory system characteristics is an important fundamental and practical task. One of the convenient ways of research is mathematical simulation, which allows to reduce the number of experiments in extreme conditions or experiments for the personal protective equipment testing, as well as to forecast the estimated time of effective human work in such conditions. The model describes the dynamics of the gas content in the 3 compartments of the biological system and the external environment represented by the 4th compartment. The external environment can be limited by the volume of the device to which a person is connected, or by the volume of a closed hermetic object, or represented by a sufficiently large volume, conditionally being an atmosphere with appropriate parameters. A mathematical model of the breathing gas exchange with the external environment (the atmosphere or any other limited space) is presented. It is the first time, the simulation results of breathing at rest, during hyperventilation and rebreathing tests are presented, including gas dynamics in the pulmonary and tissue compartments, as well as in the brain compartment. Hypercapnia ventilation reaction during rebreathing tests with a hyperoxic - hypercapnic gas mixtures and different rebreathing bags in comparison with stationary methods of breathing control study. Verification of the model by simulation results with the literature data comparison showed the simulation model’s adequacy. A sensitivity table of the simulation model behavior in response to parameters changes is presented.

Keywords: breathing under loading stress, respiration during rest, carbon dioxide, oxygen, rebreathing, mathematical simulation, gas exchange, atmosphere, human physiology, differential equations

Abstract: The number of cancer cases will grow annually and according to WHO it will reach 25 million cases a year by 2035. Radiotherapy (RT) is a key element for the treatment of the 80 % of the cases [1-3] and its development and accessibility are the main routes for further improvement. At the current moment the large percentage of the negative outcomes of the cancer treatment is attributed to either lack of the RT machines or technical personal capable to maintain it. A modular approach to structure such an equipment is one of the ways to resolve the issues. The aim of the studies is to develop a conceptual design of a single module compact accelerator for medical applications and specifically RT of cancers. Development of such a machine is an important step to resolve the RT availability and challenging task from research and design point of view. The studies carried out using analytical and numerical (CST MW studio) approaches. In this paper the conceptual design of such a monobloc traveling wave (12 GHz) accelerator with the space charge limited electron beam current is presented and discussed. The accelerating section made of set of specially designed cell with average constant accelerating potential around 40 MV/m is demonstrated and its properties are discussed. It is shown that the low-relativistic electron beam can reach energy of 10 MeV on the length of the section less than 30 cm. It is shown that the electron beam capture, modulation and transportation takes place inside the accelerating section with the beam transportation efficiency above 80 %. It is illustrated that the main beam losses are taking place at the initial stage of beam formation and ways to optimise the system and minimise the beam losses are discussed. The results of the studies are compared and good agreement is demonstrated.

Keywords: non-uniform accelerating structure, virtual cathode, space charge, traveling wave, compact linear accelerator, oncology, radiotherapy, monobloc linear accelerator, constant acceleration potential, high-current accelerator