Radiation environment in high-altitude Antarctic plateau: Recent measurements and model studies

Polar regions are the most exposed to secondary particles and radiation produced by primary cosmic rays in the atmosphere, because naturally they are with marginal geomagnetic shielding. In addition, the secondary particle flux contributing to the complex radiation field is enhanced at high-mountain altitudes compared to sea level because of the reduced atmospheric attenuation. At present, there are very few systematic experimental measurements of environmental dose at high southern latitudes, specifically at high-altitude region. Here, we report a campaign of measurements with different devices, that is passive and Liulin-type dosimeters, of the radiation background at high-mountain Antarctic station Vostok (3488 m above sea level, 78° 27' S; 106° 50' E). We compare the measurements with a Monte Carlo-based model for the propagation of the cosmic rays through the atmosphere and assessment of the radiation field in the atmosphere. We employed the model to estimate the radiation dose at Vostok station during the ground-level enhancement at 28 October 2021. As in previous studies by other teams, we show that the annual dose equivalent at high-altitude Antarctic facilities can significantly exceed the limit of 1 mSv established for the general population by the ICRP.

[Obesity and penile morphology: is there a relationship? (Experimental study)]

INTRODUCTION

Erectile dysfunction (ED) is a condition characterized by the inability to achieve or maintain an erection sufficient for sexual intercourse. The prevalence of ED ranges from 6% to 64% depending on age. Obesity is one of the factors leading to ED, which is widespread in the world. Men with obesity are 30% more likely to develop ED compared with men with normal body weight.

AIM

The aim was to identify morphological changes in the cavernous tissue of the penis of patients with obesity using the biological model of laboratory rats as an example.

MATERIALS AND METHODS

In vivo modeling of diet-induced obesity was performed. A total of 22 laboratory sexually mature white rats weighing 140-160 g were included in the study. The animals were divided into two groups, the control group (n=10) and experimental group, which included rats with diet-induced obesity (n=12). After 12 weeks, the experiment was completed. All rats underwent: 1) calculation of the Lee index (body mass index in rats); 2) determination of blood glucose level; 3) determination of the level of total cholesterol and triglycerides in the blood; 4) sampling of the penis with fixation in 10% formalin; histological sections 6-8 m thick were stained with hematoxylin and eosin, and frozen sections were prepared with subsequent staining with Sudan 3 to identify adipose cells.

RESULTS

In the experimental group, alimentary obesity developed. There were no differences in glucose and total cholesterol levels between two groups. However, a significant difference was found in the serum triglycerides level (1.24+/-0.05 mmol/L in the control group vs. 1.6+/-0.1 mmol/L in the experimental group). In the control group, the average number of adipocytes was 10+/-5 per sample; in the experimental group, their number increased by 3 times (p<0.01). In obese rats, there was an increase not only in the number of adipose cells, but also in their area compared with the control group (17.7+/-7.5 m and 12.9+/-5.3 m, respectively, p<0.01).

CONCLUSION

In rats with alimentary obesity, deposition of adipose tissue is observed not only in the visceral and paratesticular regions, but also in the cavernous tissue of the penis, which can negatively affect erectile function.

[Characteristics of postural corrective responses before and after long-term spaceflight]

Balance function is dramatically deteriorated after exposure to microgravity. The purpose of the present study was to investigate the role and the contribution of different gravity sensory systems to the development of balance impairment after long-term spaceflights. Postural perturbations (pushes to the chest) of the threshold, medium, and sub-maximal intensities were produced in eight cosmonauts before, and on the day 3, 7, and 11 following spaceflight. Postural corrective responses were analyzed by anterior-posterior body sway fluctuation and electromyographic activity of leg muscles. The characteristics of the postural corrective responses changed significantly on the day 3 following spaceflight: the amplitude of posterior sway caused by perturbation of threshold intensity was increased reaching 135% ofpreflight value; the corrective responses lasted more than 6 s in 50% of all trials, while it did not last more than 4 s in 96% before spaceflight. The EMG responses were characterized by increased contribution of medium- and long-latency reactions. On the day 11 following spaceflight, most of the characteristics of postural corrective responses were close to preflight values. We assumed that the balance alterations after spaceflight are caused by changes in weightlessness of functions of two main gravity sensory systems, namely, weight-bearing and vestibular one. The deficit of weight-bearing afferentation triggers a decline of the extensors' muscle tone, while changes of vestibular function cause a decline of accuracy of postural corrections.

[Effect of immersion hypokinesia on kinematic and electromyographic parameters of human locomotion]

Kinematics and electromyographics of the normal walking pattern were studied in 6 volunteer (22-25 y.o.) before and after immersion. It was shown that 6-d support deprivation results in reduction of angular velocities in the knee and ankle joints and minor change in the amplitude of angular motions of the joints. However, the kinematic stereotype of locomotor motions was not changed considerably following 6-days in immersion. Increase of the electromyographic cost of shin locomotion points to shifts in the central and peripheral systems of the motor apparatus.

[Effects of mechanic stimulation of the foot support zones on locomotion kinematics during 7-day dry immersion]

The dry immersion experiment involved two groups of test volunteers. In one group, the volunteers were subjected to nothing else but immersion; in the other, foot support zones of the immersed volunteers were given daily mechanic stimulation. Evaluated were kinematics of normal locomotion during a series of test walks along rigid surface at a rate of 90 steps per a minute. The results of testing brought to the conclusion that the rates of mechanic foot stimulation applied in the experiment did not change energy expenditure in the joints; however, they moderated the amplitude of angular knee joint movements following 7 days in immersion.