External respiration and gas exchange in conditions of maximum load at different levels of the body's aerobic capacity

The study of the characteristics of the reactions of the links of external respiration and gas exchange at various stages of performing a step-increasing load and at maximum load with various aerobic capabilities of the body was carried out. The data obtained indicate that the level of aerobic capabilities of the body determines the characteristics of the reactions of the links of external respiration and gas exchange at various stages of performing a step-increasing load and at maximum load. Key words: functional reserves of organism, gas transportation system, maximum oxygen consumption, aerobic capacity of organism, gas exchange.

Development of the Architecture of the System of High-Load Testing

Testing system performance and its importance at the same time is difficult to overestimate or underestimate. It would be much more correct to talk about the timeliness of this activity. Virtually any digital sys- tem built on modern approaches and technologies can work without any critical problems with its own performance. At the same time, for any system, especially when it becomes popular, it is very likely that there will be a time when it will not be able to cope with the ever-increasing load and become unstable. However, most companies that develop and maintain their own digital solutions – from websites to any other digital systems – often focus primarily on the functionality of the system and its compliance, rather than on the performance of the system as a whole. Such intentions are quite natural, because the system must properly perform the functions expected of it. When companies start to face performance problems, they try not to optimize the software as soon as possible, but to add more capacity – vertical and horizontal scaling. This strategy works, but it has limitations. After all, the addition of additional resources cannot be endless and sooner or later rests either on the architecture of the system, or in the capabilities of the company itself, and so on.Therefore it is recommended to carry out stress testing in advance, plan time and resources to have enough time to correct errors, and generally understand the boundaries of the system. At the same time, in order to organize full-fledged stress testing, trained specialists, tools and infrastructure are needed, especially when we are talking about heavy workload.As part of this work, an analysis of various tools for the implementation of stress testing and performance testing, scaling of such tests and centralized reporting of metrics. As a result, approaches and principles for the construction of a modern architecture for the implementation of the load testing subsystem in the continuous supply of code were proposed.

Energy characteristics of acoustic emission under various modes of uniaxial loading

Acoustic emissions were recorded in the process of uniaxial compression of samples of various geomaterials. The experiments were carried out on a low-noise lever setup with water leakage; the maximum load on the sample did not exceed 250 kN. Some of the samples were tested at a continuously increasing load, the other at its stepwise change. The energy distribution of acoustic emission signals was investigated. The energy characteristic of acoustic emission was the square of the maximum signal amplitude. The flow of AE events is considered from the standpoint of nonequilibrium thermodynamics and Tsallis statistics. A decrease in the steepness of the linear part of the repeatability plots for a particular geomaterial was revealed when changing the loading mode from linear to stepwise, which means an increase in the proportion of higher-energy events with a stepwise change in load.

Measurement analysis of braking forces and braking coefficient at different loads of a passenger vehicle

This paper presented an analysis of the braking force efficiency, i.e. its intensity in the case. It presented an analysis of the efficiency of braking forces, i.e. their intensity in the case when the load of a passenger vehicle was gradually changing. The change in the load of the vehicle was done by varying the number of passengers in it from one to five which is a feature of a higher number of M1 category vehicle. By increasing in the number of passengers the weight of the vehicle varied by approximately 75kg per passenger. The experimental test was performed in the technical inspection station, i.e. on standard rollers for the brake system testing. The test results shown that the relative difference of braking forces occurred on the front axle during intensive braking and that the braking coefficient was the lowest of about 69.94% in the case when only the driver was in the vehicle. It increased with increasing load, i.e. the number of passengers in the vehicle up to 85.91% and then dropped by increasing the rear passenger behind the driver and front passenger to 80.43% which can affect the stability of the vehicle when braking in the event of a dangerous traffic situation.

The Effect of Cognitive Load on the Retrieval of Long-Term Memory: An fMRI Study

One of the less well-understood aspects of memory function is the mechanism by which the brain responds to an increasing load of memory, either during encoding or retrieval. Identifying the brain structures which manage this increasing cognitive demand would enhance our knowledge of human memory. Despite numerous studies about the effect of cognitive loads on working memory processes, whether these can be applied to long-term memory processes is unclear. We asked 32 healthy young volunteers to memorize all possible details of 24 images over a 12-day period ending 2 days before the fMRI scan. The images were of 12 categories relevant to daily events, with each category including a high and a low load image. Behavioral assessments on a separate group of participants (#22) provided the average loads of the images. The participants had to retrieve these previously memorized images during the fMRI scan in 15 s, with their eyes closed. We observed seven brain structures showing the highest activation with increasing load of the retrieved images, viz. parahippocampus, cerebellum, superior lateral occipital, fusiform and lingual gyri, precuneus, and posterior cingulate gyrus. Some structures showed reduced activation when retrieving higher load images, such as the anterior cingulate, insula, and supramarginal and postcentral gyri. The findings of this study revealed that the mechanism by which a difficult-to-retrieve memory is handled is mainly by elevating the activation of the responsible brain areas and not by getting other brain regions involved, which is a help to better understand the LTM retrieval process in the human brain.

Film thickness in elastohydrodynamically lubricated slender elliptic contacts: Part I – numerical studies of central film thickness

In this paper, analytical equations for the central film thickness in slender elliptic contacts are investigated. A comparison of state-of-the-art formulas with simulation results of a multilevel elastohydrodynamic lubrication solver is conducted and shows considerable deviation. Therefore, a new film thickness formula for slender elliptic contacts with variable ellipticity is derived. It incorporates asymptotic solutions, which results in validity over a large parameter domain. It captures the behaviour of increasing film thickness with increasing load for specific very slender contacts. The new formula proves to be significantly more accurate than current equations. Experimental studies and discussions on minimum film thickness will be presented in a subsequent publication.

Condensin compacts DNA in 15 nm steps and requires FACT for extrusion on chromatin

Condensin plays a central role in the organisation of chromosomes by compacting chromatin into loops during mitosis. Condensin achieves this through a loop extrusion mechanism that remains poorly understood. To identify the molecular steps of yeast condensin during loop formation, we used optical tweezers with fluorescence detection. We find that single yeast condensin complexes use ATP to extrude DNA through distinct 15 nm steps, thus advancing ~45 base pairs (bp) per step. Under increasing load, the condensin step size remains constant while step-dwell times increase, and stalls at forces >1 pN. We also show that nucleosome arrays hinder processive condensin extrusion and demonstrate that the histone chaperone FACT is required for compaction of nucleosomal arrays by condensin. Importantly, FACT-assisted compaction on nucleosomes also occurs through distinct 15 nm steps. Finally, we show that FACT is required for correct condensin localisation in vivo. Our results establish that loop extrusion by yeast condensin involves a 45 bp stroke that requires FACT for condensin function on chromatin.

Condensin compacts DNA in 15 nm steps and requires FACT for extrusion on chromatin

Condensin plays a central role in the organisation of chromosomes by compacting chromatin into loops during mitosis. Condensin achieves this through a loop extrusion mechanism that remains poorly understood. To identify the molecular steps of yeast condensin during loop formation, we used optical tweezers with fluorescence detection. We find that single yeast condensin complexes use ATP to extrude DNA through distinct 15 nm steps, thus advancing ~45 base pairs (bp) per step. Under increasing load, the condensin step size remains constant while step-dwell times increase, and stalls at forces >1 pN. We also show that nucleosome arrays hinder processive condensin extrusion and demonstrate that the histone chaperone FACT is required for compaction of nucleosomal arrays by condensin. Importantly, FACT-assisted compaction on nucleosomes also occurs through distinct 15 nm steps. Finally, we show that FACT is required for correct condensin localisation in vivo. Our results establish that loop extrusion by yeast condensin involves a 45 bp stroke that requires FACT for condensin function on chromatin

Effect of artificial aging on the tribological properties of an Al-25Zn-1Mg alloy

The tribological properties of aluminum based Al-25Zn-1Mg alloy was experimentally investigated in an MSc thesis, and the results are presented in this study. To this purpose, Al-25Zn-1Mg was commercially produced by casting. The prepared samples were divided into seven groups: no-process, solution treatment, and artificial aging for 1, 3, 6, 12 and 24 hours. Aged and untreated samples were subjected to tribological experiments under conditions of dry friction under 5 N and 10 N loads at speed of 200 rpm, 400 rpm and 800 rpm for a distance of 500 m. As a result of the tests, it was found that hardness increases in all samples depending on the aging process. It was also found that when the test speed was kept constant, the coefficient of friction increased with increasing load.

Predictive Estimation of Sliding Bearing Load-Carrying Capacity and Tribological Durability

A computational method is presented as a method for solving a plane contact problem of the theory of elasticity to determine the contact strength and tribological durability of sliding bearings. The effect of load and radial clearance on the initial contact pressures and their reduction due to wear is studied. The durability of the bearing is estimated. Qualitative and quantitative regularities of changes in contact parameters and durability from the factors under study are established. In particular, it has been shown that both contact angles and maximum contact pressures are approximately linearly dependent on the load, and the durability decreases nonlinearly with increasing load.