[Analysis of sudden cardiac death in competitive athletes, possibilities for reducing cases]. / Versenysportolók hirtelen szívhalálának elemzése, az esetszámok csökkentésének lehetoségei.

INTRODUCTION: Sudden cardiac death in athletes is rare (0.5 to 1 per 100 000 athlete years), but sudden cardiac death in known athletes causes general shock. OBJECTIVE: Our research aim was to collect and study as many sudden cardiac death cases as possible, judge the role of stress and look for ways to reduce fatal tragedies. METHOD: From registers and newspaper articles found on the Internet, we collected 360 (including 14 women) athletes' sudden cardiac death cases where the sport, age and place of death (during training/competition/after) could be determined. From these, a single database has been prepared in order of the year of death. The cases were grouped and analyzed by sports. Based on our results and literature data, we made recommendations to reduce fatalities. RESULTS AND CONCLUSION: There were more sudden cardiac deaths in competitions than in trainings (239 vs. 99), but tragedies also happened during warm-ups and chess without physical exertion, furthermore, there was no sudden cardiac death in the stakeless training of marathon/half marathon/triathlon athletes; all these prove the role of stress, so we recommend a psychological conversation before a high-stakes race. There were also a lot of sudden cardiac deaths (79/360) during team sports trainings, so we recommend reanimation readiness there as well. After training/competition, sudden cardiac death happened mainly in sports requiring high static effort, where post-competition monitoring is also recommended. Those who died in training were younger than those who died during the race (p<0.01), so young people should be monitored more closely for medical and (under)fitness. Marathon runners and triathletes were older than team athletes (p<0.005) and only died in competition, so for them a basic examination and an ECG within 1 month before competition are recommended. Conclusions drawn from literature data: sports medicine examination should be standardized and documented in an accessible way; since resuscitation started earlier and professionally is more effective, all competitors should receive reanimation training. Orv Hetil. 2023; 164(29): 1155-1163.

On-target temporal characterization of optical pulses at relativistic intensity.

High-field experiments are very sensitive to the exact value of the peak intensity of an optical pulse due to the nonlinearity of the underlying processes. Therefore, precise knowledge of the pulse intensity, which is mainly limited by the accuracy of the temporal characterization, is a key prerequisite for the correct interpretation of experimental data. While the detection of energy and spatial profile is well established, the unambiguous temporal characterization of intense optical pulses, another important parameter required for intensity evaluation, remains a challenge, especially at relativistic intensities and a few-cycle pulse duration. Here, we report on the progress in the temporal characterization of intense laser pulses and present the relativistic surface second harmonic generation dispersion scan (RSSHG-D-scan)-a new approach allowing direct on-target temporal characterization of high-energy, few-cycle optical pulses at relativistic intensity.

1 kW, 200 mJ picosecond thin-disk laser system.

We report on a laser system based on thin-disk technology and chirped pulse amplification, providing output pulse energies of 200 mJ at a 5 kHz repetition rate. The amplifier contains a ring-type cavity and two thin Yb:YAG disks, each pumped by diode laser systems providing up to 3.5 kW power at a 969 nm wavelength. The average output power of more than 1 kW is delivered in an excellent output beam characterized by M2=1.1. The output pulses are compressed to 1.1 ps at full power with a pair of dielectric gratings.

Direct regenerative amplification of femtosecond pulses to the multimillijoule level.

We present a compact femtosecond nonlinear Yb:YAG thin-disk regenerative amplifier delivering pulses carried at a wavelength of 1030 nm with an average power of >200 W at a repetition rate of 100 kHz and an energy noise value of 0.46% (rms) in a beam with a propagation factor of M2<1.4. The amplifier is seeded with bandwidth-limited subpicosecond pulses without temporal stretching. We give estimates for the nonlinear parameters influencing the system and show that chirped mirrors compress the 2 mJ pulses to a near-bandwidth-limited duration of 210 fs.

Treatment of Hypertension: Favourable Effect of the Twice-Daily Compared to the Once-Daily (Evening) Administration of Perindopril and Losartan.

BACKGROUND/AIMS: Little is known about the effect of twice daily administration of same dose of ACE inhibitor and ARB on the diurnal/nocturnal blood pressure (BP) ratio. We aimed to assess the effect of two widely used long-acting drugs: perindopril and losartan in the treatment of hypertension comparing the once-daily (evening) vs. twice-daily (morning and evening) administration with the same daily doses. METHODS: Untreated primary hypertensive patients without complaints (a total of 164: 65 men, 99 women, 55.7 ± 13.7 years of age, 41-41 patients per treated groups) were selected with non-dipper phenomenon, estimated by diurnal index (DI) <10%. The effect of evening (8 mg perindopril or 100 mg losartan) vs morning and evening (4-4 mg perindopril or 50-50 mg losartan) administration was determined on a 14-day treatment by ABPM. RESULTS: The mean BP, the percent time elevation index, and the hyperbaric impact decreased in both drug groups. Significant difference was observed in the DI in the case of twice-daily administration vs once-daily evening dosing. CONCLUSIONS: The twice-daily administration with the same daily dose of perindopril or losartan seems to be more effective compared to the once daily evening administration in eliminating the non-dipper phenomenon. According to some authors the non-dipping phenomenon increases cardiovascular risk, while others are of the opinion that the association of non-dipping with cardiovascular events does not necessarily mean that selective treatment of non-dipping improves cardiovascular outcomes.

Left Ventricular Morphology in Different Periods of the Training Season in Elite Young Swimmers.

Training adaptation of the left ventricle (LV) and it's reversibility following the cessation of training in adults is well known and also studied in children. In the current study we describe the changes in the LV morphology in association with the training season during a 1.5 year follow-up period. 15 elite adolescent swimmers, seven girls and 8 boys with 6 years of swimming history and 20 hr per week training were observed. Their data were compared with 15 age and gender matched nonathletes. LV adaptation was measured with 2D-echocardiography at the baseline preseason and every 3 months, according to the macro cyclic periods of training. Nonathletes were observed at the first and fifth stage of the study. Remarkable LV morphological adaptation has been detected in the swimmers. The greatest LV muscle mass (LVMM: 228 ± 46g) and smallest end-diastolic diameter (LVIDd:44.9 ± 3.4mm) were observed at the end of the second general endurance preparation period (GEP2), but the LVMM/BSA (Rel.LVMM: 85 ± 10g/m) failed to change during the follow-up in athletes. On the basis of our results, we suggest comparing absolute LV dimensions only in studies made at the same training period to avoid bias due to alterations with the training season.

Pump-seed synchronization for MHz repetition rate, high-power optical parametric chirped pulse amplification.

We report on an active synchronization between two independent mode-locked lasers using a combined electronic-optical feedback. With this scheme, seed pulses at MHz repetition rate were amplified in a non-collinear optical parametric chirped pulse amplifier (OPCPA). The amplifier was seeded with stretched 1.5 nJ pulses from a femtosecond Ti:Sapphire oscillator, while pumped with the 1 ps, 2.9 µJ frequency-doubled output of an Yb:YAG thin-disk oscillator. The residual timing jitter between the two oscillators was suppressed to 120 fs (RMS), allowing for an efficient and broadband amplification at 11.5 MHz to a pulse energy of 700 nJ and an average power of 8 W. First compression experiment with 240 nJ amplified pulse energy resulted in a pulse duration of ~10 fs.

Experimental and theoretical investigation of timing jitter inside a stretcher-compressor setup.

In an optically synchronized short-pulse optical-parametric chirped-pulse amplification (OPCPA) system, we observe a few-100 fs-scale timing jitter. With an active timing stabilization system slow fluctuations are removed and the timing jitter can be reduced to 100 fs standard deviation (Std). As the main source for the timing fluctuations we could identify air turbulence in the stretcher-compressor setup inside the chirped pulse amplification (CPA) pump chain. This observation is supported by theoretical investigation of group delay changes for angular deviations occurring between the parallel gratings of a compressor or stretcher, as they can be introduced by air turbulence.

Broadband amplification by picosecond OPCPA in DKDP pumped at 515 nm.

On the quest towards reaching petawatt-scale peak power light pulses with few-cycle duration, optical parametric chirped pulse amplification (OPCPA) pumped on a time scale of a few picoseconds represents a very promising route. Here we present an experimental demonstration of few-ps OPCPA in DKDP, in order to experimentally verify the feasibility of the scheme. Broadband amplification was observed in the wavelength range of 830-1310 nm. The amplified spectrum supports two optical cycle pulses, at a central wavelength of ~920 nm, with a pulse duration of 6.1 fs (FWHM). The comparison of the experimental results with our numerical calculations of the OPCPA process showed good agreement. These findings confirm the reliability of our theoretical modelling, in particular with respect to the design for further amplification stages, scaling the output peak powers to the petawatt scale.

Resting blood pressure values of adult athletes.

BACKGROUND: Regular physical activity has a favorable effect upon the prevention and treatment of hypertension. Various movements in sports, however, affect blood pressure (BP) differently. METHODS: In the present study, the resting BP data of a large number (3,697) of young men and women (age: 19-40 years) who participated in sports medical examinations were compared according to their sport. Athletes were arranged into definite subgroups based on their different sport activities, i.e. if their movement pattern characteristics were similar and no significant intergroup differences were seen in BP values. RESULTS: BP values were lower in the dynamic type athletes (speed, endurance sports and ball games) than in the static type. Out of the endurance athletes, BP values were not lower in cycle racers, kayakers/canoeists and rowers. In water athletes, BP values were higher than in corresponding dry-land athletes. There was a quite large significant difference between the BP values of athletes involved in static muscular activity (power athletes) and dynamic-type strength athletes (combat competitors). CONCLUSIONS: Although cycling, kayaking/canoeing and competitive water sports increase BP, as leisure time activities they more than likely do not elevate BP.

High energy picosecond Yb:YAG CPA system at 10 Hz repetition rate for pumping optical parametric amplifiers.

We present a chirped pulse amplification (CPA) system based on diode-pumped Yb:YAG. The stretched ns-pulses are amplified and have been compressed to less than 900 fs with an energy of 200 mJ and a repetition rate of 10 Hz. This system is optically synchronized with a broadband seed laser and therefore ideally suited for pumping optical parametric chirped pulse amplification (OPCPA) stages on a ps-timescale.

Simulations of petawatt-class few-cycle optical-parametric chirped-pulse amplification, including nonlinear refractive index effects.

We present three-dimensional simulations of optical-parametric chirped-pulse amplification stages for a few-cycle petawatt-class laser. The simulations take into account the effects of depletion, diffraction, walk-off, quantum noise, and the nonlinear refractive index (n(2)). In the absence of n(2) effects, we show these stages can generate 3.67J pulses supporting 4fs transform-limited pulse durations. Adding the nonlinear refractive index to the simulation, the energy output is reduced by ~11% and the bandwidth narrows by ~129nm, increasing the Fourier limit by ~17.5%.

Generation of 220 mJ nanosecond pulses at a 10 Hz repetition rate with excellent beam quality in a diode-pumped Yb:YAG MOPA system.

A novel all-diode-pumped master oscillator power amplifier system based on Yb:YAG crystal rods has been developed. It consists of a Q-switched oscillator delivering 3 mJ, 6.4 ns pulses at a 10 Hz repetition rate and an additional four-pass amplifier, which boosts the output energy to 220 mJ, while a close to TEM(00) beam quality could be observed. Additionally a simulation of the amplification was written that allows for further scaling considerations.