Reduction of the auto seismic component of error of a ballistic laser gravimeter by excitation of an induction-dynamic catapult from an AC voltage source

The purpose of the study is to analyse the influence of the excitation of an induction-dynamic catapult of a ballistic laser gravimeter from an AC voltage source at different frequencies on electromechanical indicators that provide a reduced value of the auto seismic component of error in measuring the gravitational acceleration g due to a decrease in the recoil force. A mathematical model of the gravimeter catapult when excited from an AC voltage source is proposed, taking into account the interrelated electrical, magnetic and mechanical processes. The nature of the electromechanical processes in the catapult of the gravimeter with such excitation has been established. It is shown that a phase shift occurs between the currents in active elements, as a result of which positive (repulsive) pulses of the electrodynamic force alternate with negative (attractive) pulses of force. A criterion for the efficiency of the gravimeter catapult has been introduced, taking into account the maximum value of push of the test body at the smallest values of the electrodynamic force and current of the inductor winding. It was found that the highest efficiency of the gravimeter catapult is provided at a frequency of 250 Hz, at which the catapult efficiency is 3.5 times higher than at a frequency of 50 Hz. It is shown that the transition from the method of excitation of an induction-dynamic catapult with one short pulse to excitation from an AC voltage source makes it possible to reduce the uncertainty in measuring the gravitational acceleration.

High-Intensity Functional Training Guided by Individualized Heart Rate Variability Results in Similar Health and Fitness Improvements as Predetermined Training with Less Effort

Heart rate variability (HRV) may be useful for prescribing high-intensity functional training (HIFT) exercise programs. This study aimed to compare effects of HRV-guided and predetermined HIFT on cardiovascular function, body composition, and performance. Methods: Recreationally-active adults (n = 55) were randomly assigned to predetermined HIFT (n = 29, age = 24.1 ± 4.1 years) or HRV-guided HIFT (n = 26, age = 23.7 ± 4.5) groups. Both groups completed 11 weeks of daily HRV recordings, 6 weeks of HIFT (5 d·week-1), and pre- and post-test body composition and fitness assessments. Meaningful changes in resting HRV were used to modulate (i.e., reduce) HRV-guided participants’ exercise intensity. Linear mixed models were used with Bonferroni post hoc adjustment for analysis. Results: All participants significantly improved resting heart rate, lean mass, fat mass, strength, and work capacity. However, no significant between-groups differences were observed for cardiovascular function, body composition, or fitness changes. The HRV-guided group spent significantly fewer training days at high intensity (mean difference = −13.56 ± 0.83 days; p < 0.001). Conclusion: HRV-guided HIFT produced similar improvements in cardiovascular function, body composition, and fitness as predetermined HIFT, despite fewer days at high intensity. HRV shows promise for prescribing individualized exercise intensity during HIFT.

Prediction method of Ultra-wideband electromagnetic pulse coupling in slotted cavity

With the develofpment of UWB electromagnetic pulse radiation systems, people are paying more and more attention to its serious threat to electronic equipment. The effect of UWB electromagnetic pulse has also become an important content in the field of electromagnetic compatibility. In an UWB radiation system, the distance between the device under test and the transmitting antenna is different, and the radiation field received is also different. Therefore, in actual tests, the test body is often placed at different distances from the antenna to perform multiple measurements to obtain test data as required. Based on this, this article takes the cavity as an example, and proposes a method of using the system transfer function to predict the response of the impulse field inside the cavity to simplify the test and quickly obtain the test data. Firstly, the impulse field response of a certain point with and without a cavity is measured respectively, and then the time domain response is inversely Fourier transformed to obtain the frequency domain transfer function of the test body. Finally, using the transfer function to convolute with the field to be measured, the response of the impulse field inside the cavity can be predicted under the condition of the field to be measured. It is verified by experiments that this method can better predict the response of the impulse field inside the cavity under different distance conditions, and has the characteristics of simple calculation and good prediction effect. At the same time, the transfer function obtained by this method can be used to predict the arbitrary impulse field response of the cavity in its frequency range.

The Correlation Between the 2-Minute Step Test and Body Mass Index in Thai Community-Dwelling Older Adults

Objective: To determine and compare the 2-minute step test (2MST) scores among different body mass index (BMI) of elderly subjects and to predict the cardiorespiratory performance in community-dwelling older adults. Materials and Methods: Ninety subjects, aged 60 or older were assigned for cardiorespiratory performance using the 2MST. Results: There were significant differences in the 2MST scores among normal weight, overweight, and obese elders. The lowest score of the 2MST was found in obese elders when compared with normal weight and overweight elders. Moreover, BMI was negatively correlated with the 2MST (r=–0.83, p<0.05). Conclusion: Community-dwelling obese elders had decreased cardiorespiratory performance, and BMI was negatively correlated with cardiorespiratory performance in obese elders. Keywords: 2-minute step test; Body mass index; Elderly; Cardiorespiratory performance; Physical therapy

Freeze tolerance in neotropical frogs: an intrageneric comparison using Pristimantis species of high elevation and medium elevation

Paramos are high-elevation tropical Andean ecosystems above the tree line that display variable temperature and frequent freezing spells. Because a significant anuran community lives in this environment, physiological protection against freezing must characterise individuals in this community. Antifreeze protection has been studied in amphibians from other communities, and it is likely that Paramo anurans rely on the same underlying molecules that convey such protection to Nearctic species. However, given the pervasive presence of freezing spells in the Paramos year-round, the processes of activating protection mechanisms may differ from that of seasonal counterparts. Accordingly, this study investigated cryoprotection strategies in high-elevation tropical frogs, using as a model the terrestrial and nocturnal genus Pristimantis, specifically P. bogotensis, P. elegans and P. nervicus from Paramos, and the warm ecosystem counterparts P. insignitus, P. megalops and P. sanctaemartae. We focused on freeze tolerance and its relationship with glucose accumulation and ice formation. Under field conditions, the highest elevation P. nervicus exhibited higher glucose concentration at dawn compared to noon (1.7 ± 0.6 mmol/L versus 3.5 ± 1.32 mmol/L). Under experimental thermal freeze exposure for 2 hours between −2 and −4 ºC, the glucose concentration of the three Paramo species increased but physiological diversity was evident (P. nervicus 126%; P. bogotensis 100%; and P. elegans 55%). During this test, body ice formation was assessed calorimetrically. The species with the highest body ice formation was P. bogotensis (17% ± 5.37; maximum value: 63%; n = 8), followed by P. nervicus (5% ± 3.27; maximum value: 11%; n = 5) and P. elegans (0.34% ± 0.09; maximum value: 1%; n = 4). The study shows physiological diversity both within a genus and across the amphibian community around the freezing contour. Overall, Paramo species differ in freezing physiology from their low-elevation counterparts. Thus, climate shifts increasing freezing spells may affect the structure of communities in this zone.

Obesity and Asthma: An Intriguing Link in Childhood and Adolescence

<b><i>Background:</i></b> Asthma is a chronic disease characterized by airway inflammation. Obesity is common and may be associated with asthma. <b><i>Objective:</i></b> The objective of this study is to investigate the possible relationship between asthma control and obesity in children. <b><i>Methods:</i></b> A nationwide study included 462 children and adolescents, 319 (69%) males, mean age 11.3 years. Asthma control grade, asthma control test, body mass index calculated as percentiles, and lung function were evaluated. <b><i>Results:</i></b> Obesity affected 64 (13.9%) children with asthma. This outcome underlined the high prevalence of obesity in children and adolescents with asthma. On the other hand, obesity did not affect the asthma control as well as lung function. <b><i>Conclusion:</i></b> This study showed that body weight did not affect asthma control and lung function in a large population of children and adolescents with asthma followed in Italian tertiary allergy/asthma centers and adequately managed.

TO THE QUESTION OF THE CALCULATING OF THE SPECIAL DEVICES CHARACTERISTICS WITH A MAGNETIC SYSTEM BASED ON THE PERMANENT MAGNETS

The creation of modern computer-aided design systems for devices and electrical machines of new generation, built on the basis of permanent magnets, necessitates the development of new mathematical models and effective computational algorithms. Based on mathematical models and using IT technologies, it is possible to develop both separate functional CAD blocks and an integrated system for calculating device parameters and modeling its characteristics. The paper considers a typical design of an electromechanical device with permanent magnets, which create a field with specified characteristics in the working area. At the first stage of the study, the heterogeneity of the environment was not taken into account. To calculate the strength of the magnetic field created by rectangular magnets, two mathematical models were obtained. This approach made it possible, first, to check the results of calculations and, secondly, to use mathematical models for comparative analysis when performing numerical modeling of the magnetic field characteristics for a system built, for example, using cylindrical magnets. On the foundation of developed mathematical model, an algorithm for analyzing the initial characteristics of a special device with permanent magnets is proposed. Devices of this type can be used to register small displacements. At the same time, the very scheme of the magnetic system and mathematical models describing the properties of the magnetic field can be used in the development of other types of electrical devices built using permanent magnets. A number of experiments on numerical simulation of the magnetic field pattern in the working area of the device were performed in the work. The results of the sensor signal simulation during the movement of the test body are also presented.