Collisional and thermal ionization of sodium Rydberg atoms I. Experiment for nS and nD atoms with n=8-20

Collisional and thermal ionization of sodium nS and nD Rydberg atoms with n=8-20 has been studied. The experiments were performed using a two-step pulsed laser excitation in an effusive atomic beam at atom density of about 2 10^{10} cm^{-3}. Molecular and atomic ions from associative, Penning, and thermal ionization processes were detected. It has been found that the atomic ions were created mainly due to photoionization of Rydberg atoms by photons of blackbody radiation at the ambient temperature of 300K. Blackbody ionization rates and effective lifetimes of Rydberg states of interest were determined. The molecular ions were found to be from associative ionization in Na(nL)+Na(3S) collisions. Rate constants of associative ionization have been measured using an original method based on relative measurements of Na_{2}^{+} and Na^{+} ion signals.Comment: 23 pages, 10 figure

The effect of acute caffeine ingestion on physical performance in elite European competitive soccer match-play

The present study examined the effect of acute caffeine ingestion (150 mg) on the physical performance of elite European soccer players during official competitive match-play. The current investigation was a parallel-group design that collated data from a cohort of 19 male outfield players from an elite European soccer team (mean ± SD, age 26 ± 4 years; weight 80.5 ± 8.1 kg; height 1.83 ± 0.07 m; body-fat 10.8 ± 0.7%). Players were classified and matched by position and grouped accordingly: centre defender (CD) n = 5, wide defender (WD) n = 3, centre midfield (CM) n = 7, wide forward (WF) n = 2, and centre forward (CF) n = 2. For all performance variables, the mean values were compared in caffeine consumers vs. non consumers using independent-sample t-tests, with significance set at p < .05. Cohen’s d was used to quantify the effect size, and was interpreted as trivial (<0.2), small (0.2-0.5), medium (0.5-0.8), and large (>0.8). For all examined variables, there were trivial or small non-significant (p > .05) trivial or small differences between caffeine consumers and non-consumers. The findings of the present research did not confirm the study hypothesis, once running and accelerometry-based variables did not improve with the caffeine ingestion of 150 mg. Therefore, the caffeine supplement used in this study is not suggested for improving performance in the variables analysed

The severity and dynamics of changes in the serum concentration of biochemical markers of muscle tissue damage in an experienced ultramarathon runner after overcoming a distance of 165 km against the background of continuing physical activity

Purpose: to determine the severity and dynamics of changes in the concentration of biochemical markers of muscle tissue damage in the blood serum of an experienced ultramarathon runner after overcoming a distance of 165 kilometers.Materials and methods: measurement of serum concentrations of markers of muscle tissue damage (aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), creatine kinase MB (CK-MB), myoglobin) in serum before and 16 and 144 hours after ultramarathon in an experienced runner (age 36, height 186 cm, weight 76 kg, body mass index 21.96).Results: 16 hours after the end of the race, extremely high levels of AST, ALT, CK, CK-MB and myoglobin were observed, the combination of which indicates severe rhabdomyolysis. After 144 hours, a decrease in the level of all markers of muscle tissue damage, including myoglobin, was noted, however, they continued to remain significantly higher than the reference values. At the same time, the athlete did not have any significant pathological symptoms, and he continued to train in the recovery mode.Conclusion: ultramarathon races lead to significant muscle damage, which can lead to rhabdomyolysis. Its severity may not correlate with any significant clinical manifestations

The impact of injury on match running performance following the return to competitive match-play over two consecutive seasons in elite European soccer players

Based on the assessment and diagnosis, the rest period following a moderate/severe injury may lead to deconditioning for the injured player and therefore an association with a prolonged rehabilitation, re-conditioning and return to sport is observed post-injury. The aim of the present study was to assess the impact of all injuries on match running performance following the return to competitive match-play over two consecutive seasons in elite European soccer players. A retrospective analysis was conducted utilizing data related to a player’s injury and match running performance. A club physiotherapist consistently recorded availability and injury data in a standardized format. Linear mixed modelling analysis revealed no difference between PRE and POST1, POST2, and POST3 for total distance, running distance, high-intensity distance, and sprint distance (all p >0.05). Although, maximum speed was significantly (p<0.05) lower in POST1 and POST2 when compared to PRE, in both cases with a large (ES = 1.88) effect. No significant difference was observed for maximum speed between PRE and POST3 (p=0.07). There were very low correlations between the number of days absent and changes in maximum speed between POST1 and PRE (r = 0.09, 95% CI -0.42 to 0.56), and POST2 and PRE (r = 0.10, 95% CI -0.42 to 0.57), respectively. In conclusion, no variation in distance variables were found regardless of one, two or three matches post-injury compared to pre-injury status. Moreover, maximum speed was lower during the first three matches post-injury, although the mean value was slightly lower. Finally, a low correlation between absent days and maximum speed loss between pre-injury and following one and two matches were foun

The assessment of the structure of anti-doping rules violation and the evaluation of anti-doping measures efficiency in Russian athletics during 2000–2020

The assessment of the structure and trends of doping perpetrations among athletes with a proven high prevalence of doping use might be of great practical interest. Non-compliance with the zero-tolerance policy towards anti-doping rules violators among sports communities with a high prevalence of doping offenses is the main cause of the ineffective fight against doping.Objective: to analyze the structure of anti-doping rule violations and evaluate the effectiveness of measures to counter the spread of doping in Russian athletics in 2000–2020.Materials and methods: to form an objective picture, a database was collected on all anti-doping rule violators in Russian athletics from 2000 to June 01, 2020 from open sources. Retrospective analysis of the protocols of all official competitions held in Russia since 2000 and included in the RUSAF Unified Schedule was performed.Results: 381 cases of anti-doping rule violation committed during 2000–2020 period by 355 athletes were registered. 25 athletes committed 2 doping offenses and 1 athlete 3 ones. Women perpetrated more offenses than men.Conclusions: our study objectified the doping issue in Russian athletics and evaluated the effectiveness of anti-doping measures. The study indicates the need to stop ignoring zero-tolerance policy principles towards doping offenders among the athletic community and creates an incentive to develop functional mechanisms to combat doping

Application of isokinetic extremity system in sport medicine and rehab practice

The literature review discusses current trends in the isokinetic machines (IM) use for both training and diagnostic purposes. The review dwells upon a wide range of IM applications, testing and training results, and demonstrates the applied nature of the IM use. The review addresses the issues IM use in professional sports. We come to the conclusion about a wide range of IM applications in both research and clinical practice. Despite IM disadvantages (high cost, necessity of special staff training, test results variability depending on an IM model), IM is a powerful tool in a health care professional’s arsenal which provides a qualitative improvement of clinical practice

Broadening and intensity redistribution in the Na(3p3p) hyperfine excitation spectra due to optical pumping in the weak excitation limit

Detailed analysis of spectral line broadening and variations in relative intensities of hyperfine spectral components due to optical pumping is presented. Hyperfine levels of sodium $3p_{1/2}$ and $3p_{3/2}$ levels are selectively excited in a supersonic beam at various laser intensities under the conditions when optical pumping time is shorter than transit time of atoms through the laser beam. The excitation spectra exhibit significant line broadening at laser intensities well below the saturation intensity, and redistribution of intensities of hyperfine spectral components is observed, which in some cases is contradicting with intuitive expectations. Theoretical analysis of the dynamics of optical pumping shows that spectral line broadening depends sensitively on branching coefficient of the laser-driven transition. Analytical expressions for branching ratio dependent critical Rabi frequency and critical laser intensity are derived, which give the threshold for onset of noticeable line broadening by optical pumping. Transitions with larger and smaller branching coefficients are relatively less affected. The theoretical excitation spectra were calculated numerically by solving density matrix equations of motion using the split propagation technique, and they well reproduce the observed effects of line broadening and peak intensity variations. The calculations also show that presence of dark (i.e., not laser- coupled) Zeeeman sublevels in the lower state results in effective branching coefficients which vary with laser intensity and differ from those implied by the sum rules, and this can lead to peculiar changes in peak ratios of hyperfine components of the spectra.Comment: 12 pages, 10 figure

The effect of acute caffeine ingestion on physical performance in elite European competitive soccer match-play

The present study examined the effect of acute caffeine ingestion (150mg) on the physical performance of elite European soccer players during official competitive match-play. The current investigation was a parallel-group design that collated data from a cohort of 19 male outfield players from an elite European soccer team (mean ± SD, age 26 ± 4 years; weight 80.5 ± 8.1kg; height 1.83 ± 0.07m; body-fat 10.8 ± 0.7%). Players were classified and matched by position and grouped accordingly: center defender (CD) n = 5, wide defender (WD) n = 3, center midfield (CM) n = 7, wide forward (WF) n = 2, and center forward (CF) n = 2. For all performance variables, the mean values were compared in caffeine consumers vs. non consumers using independent-sample t-tests, with significance set at p0.8). For all examined variables, there were trivial or small non-significant (p>0.05) trivial or small differences between caffeine consumers and non-consumers. The findings of the present research did not confirm the study hypothesis, once running and accelerometry-based variables did not improve with the caffeine ingestion of 150mg. Therefore, the caffeine supplement used in this study is not suggested for improving performance in the variables analysed

Effect of photoions on the line shapes of the F\"orster resonance and microwave transitions in cold rubidium Rydberg atoms

Experiments on the spectroscopy of the F\"orster resonance Rb(37P)+Rb(37P) -> Rb(37S)+Rb(38S) and microwave transitions nP -> n'S, n'D between Rydberg states of cold Rb atoms in a magneto-optical trap have been performed. Under ordinary conditions, all spectra exhibited a 2-3 MHz line width independently of the interaction time of atoms with each other or with microwave radiation, although the ultimate resonance width should be defined by the inverse interaction time. Analysis of the experimental conditions has shown that the main source of the line broadening was the inhomogeneous electric field of cold photoions appeared at the excitation of initial Rydberg nP states by broadband pulsed laser radiation. Using an additional pulse of the electric field, which rapidly removed the photoions after the laser pulse, lead to a substantial narrowing of the microwave and F\"orster resonances. An analysis of various sources of the line broadening in cold Rydberg atoms has been conducted.Comment: 10 pages, 6 figure