The importance of ST elevation in V2-4 ECG leads in athletes.

BACKGROUND: Early repolarization in the anterior ECG leads (ERV2-4) is considered to be a sign of right ventricular (RV) remodeling, but its etiology and importance are unclear. METHODS: A total of 243 top-level endurance-trained athletes (ETA; 183 men and 60 women, weekly training hours: 15-20) and 120 leisure-time athletes (LTA; 71 men and 49 women, weekly training hours: 5-6) were investigated. The ERV2-4 sign was evaluated concerning type of sport, gender, transthoracic echocardiographic parameters, and ECG changes, which can indicate elevated RV systolic pressure [left atrium enlargement (LAE), right atrium enlargement (RAE), RV conduction defect (RVcd)]. RESULTS: Stroke volume and left ventricular mass were higher in ETAs vs. LTAs in both genders (p < 0.01). Prevalence of the ERV2-4 sign was significantly higher in men than in women [p = 0.000, odds ratio (OR) = 36.4] and in ETAs than in LTAs (p = 0.000). The highest ERV2-4 prevalence appeared in the most highly trained triathlonists and canoe and kayak paddlers (OR = 13.8 and 5.2, respectively). Within the ETA group, the post-exercise LAE, RAE, and RVcd changes developed more frequently in cases with than without ERV2-4 (LAE: men: p < 0.05, females: p < 0.005; RAE: men: p < 0.05, females: p < 0.005; RVcd: N.S.). These post-exercise appearing LAE, RAE, and RVcd are associated with the ERV2-4 sign (OR = 4.0, 3.7, and 3.8, respectively). CONCLUSIONS: According to these results, ERV2-4 develops mainly in male ETAs due to long-lasting and repeated endurance training. The ERV2-4 sign indicates RV's adaptation to maintain higher compensatory pulmonary pressure and flow during exercise but its danger regarding malignant arrhythmias is unclear.

10 W CEP-stable few-cycle source at 2 µm with 100 kHz repetition rate.

We developed a high repetition rate optical parametric chirped-pulse amplification (OPCPA) laser system based on fiber-laser-seeded Innoslab to generate few-cycle pulses around 2 µm with passively stable carrier-envelope phase (CEP) by difference frequency generation (DFG). Incorporating a piezo mirror before the DFG stage permits rapid CEP control. The OPCPA system is seeded by a stable supercontinuum generated in bulk material with the picosecond Innoslab pulses. Few-cycle pulses with durations of 17 fs and energies of over 100 µJ were produced in a single OPCPA stage. Three different nonlinear crystals: BBO, BiBO, and LNB were tested in the final parametric amplifier, and their average power related limitations are addressed.

Discrete dispersion scanning as a simple method for broadband femtosecond pulse characterization.

A simple and easy to implement technique for femtosecond pulse characterization is proposed and experimentally verified. It is based on the introduction of a known amount of dispersion (by controlling the number of passes through dispersive material) and subsequent recording of the spectral positions of second harmonic peaks obtained in a non-linear crystal. Such dependence allows for direct retrieval of the pulse spectral phase. The presented pulse characterization method is beneficial especially for broadband pulses, where the second harmonic spectrum exceeds the detection bandwidth of a single spectrometer.

Comparison of left and right ventricular adaptation in endurance-trained male athletes.

Characteristics of the athlete's heart have been investigated mostly in the left ventricle (LV); reports referring to the right ventricle (RV) have only appeared recently. The aim of the present study was to compare the training effects on RV and LV in elite male endurance athletes. To this end, echocardiography was conducted in 52 elite endurance athletes (A) and in 25 non-athletes (NA). Differences between A and NA in the morphology was more marked in the RV (body-size-matched (rel.)) long axis diastolic diameter (RVLADd): 63.4 ± 6.3 vs. 56.4 ± 6.3; rel. short axis diastolic diameter (RVSADd): 27.3 ± 3.6 vs. 23.6 ± 2.7 mm/m, RV diastolic area 28 ± 5.0 vs. 21.3 ± 4.3 cm2 in all cases, p < 0.001) than in the LV (rel. LVLADd: 63.8 mm/m ± 5.6 vs. 60.7 mm/m ± 6.6, p < 0.05, rel.LVSADd 37.8 ± 3.1 vs. 35.3 ± 2.4, no difference). In the athletes ratios of peak early to late diastolic filling velocity (2.07 ± 0.51 vs. 1.75 ± 0.36, p < 0.01), the TDI-determined E'/A' ratio in the septal (1.89 ± 0.55 vs. 1.62 ± 0.55, p < 0.05) and lateral (2.62 ± 0.72, vs. 2.18 ± 0.87, p < 0.001) walls were significantly higher than in NA only in the LV. Results indicate that in male endurance athletes morphologic adaptation is similar or slightly stronger in the RV than in the LV, functional adaptation seems to be stronger in the LV.

800-fs, 330-µJ pulses from a 100-W regenerative Yb:YAG thin-disk amplifier at 300 kHz and THz generation in LiNbO3.

Yb:YAG thin-disk lasers offer extraordinary output power, but systems delivering femtosecond pulses at a repetition rate of hundreds of kilohertz are scarce, even though this regime is ideal for ultrafast electron diffraction, coincidence imaging, attosecond science, and terahertz (THz) spectroscopy. Here we describe a regenerative Yb:YAG amplifier based on thin-disk technology, producing 800-fs pulses at a repetition rate adjustable between 50 and 400 kHz. The key design elements are a short regenerative cavity and fast-switching Pockels cell. The average output power is 130 W before the compressor and 100 W after compression, which at 300 kHz corresponds to pulse energies of 430 and 330 µJ, respectively. This is sufficient for a wide range of nonlinear conversions and broadening/compression schemes. As a first application, we use optical rectification in LiNbO3 to produce 30-nJ single-cycle THz pulses with 6 W pump power. The electric field exceeds 10 kV/cm at a central frequency of 0.3 THz, suitable for driving structural dynamics or controlling electron beams.

Pulse compression to subcycle field waveforms with split-dispersion cascaded hollow fibers.

Carefully dispersion- and nonlinearity-managed cascades of gas-filled hollow-core fibers enable, as our theoretical analysis shows, efficient pulse compression with ultrahigh compression ratios. With dispersion and nonlinearity of individual fibers in such cascades optimized toward distinctly different goal functions, millijoule picosecond laser pulses can be compressed to sub-100-GW subcycle field waveforms.

The athlete's heart. Part II: influencing factors on the athlete's heart: types of sports and age (review).

In our previous review characteristics of the athlete's heart were divided into three groups: morphologic (left ventricular (LV) hypertrophy, improved coronary circulation), functional (better diastolic function) and regulatory (lower heart rate (HR)) features. In the present review, the influences of the types of sports and the age on the athlete's heart are discussed. Studies using echocardiographic, Doppler-echocardiographic, tissue Doppler imaging (TDI) and magnetic resonance imaging (MRI) results are mostly involved. The coronary circulation was investigated overwhelmingly in animal experiments. In the LV hypertrophy a major contributor is the increase of the LV wall thickness (WT) than that of the LV internal diameter (ID). A right ventricular (RV) hypertrophy can also be seen in athletes. Athletic features are induced mostly by endurance training. Approximately two years regular physical training is needed to develop characteristics of the athlete's heart, hence, in the young children they are less marked. LV hypertrophy and lower HR are characteristic in young and adult athletes, but they are less marked in older ones. A richer coronary capillary network can develop mostly at a young age.

Relationship between the heart rate and E/A ratio in athletic and non-athletic males.

UNLABELLED: To clarify whether the higher E/A quotient of male athletes is a favourable change in the intrinsic relaxation properties of the left ventricle. METHODS: Peak early (E) and atrial blood flow velocities (A) were assessed by Doppler echocardiography at rest in 1237 males (939 athletes) in Hungary. Data were collected between 1993 ­ 2009. Relationship between E/A and resting heart rate (HR), was determined by linear regression analysis. RESULTS: The E/A decreased with age, the rate of decrease was slower in the physically trained subjects, except in children. In children, adolescent-young and young adult subjects E/A against HR equations of the athletic and nonathletic groups were similar, differences between the means were only due to the differences of the HR. In the 31 ­ 44 yr old males, the intercepts of the athletes' regression lines were higher. The oldest (>44 yr) active subjects showed a significant regression while sedentary males did not. CONCLUSIONS: The HR-independent beneficial effect of regular physical training on the diastolic function manifests itself at the older ages. The impact of resting HR should always be taken into consideration when assessing intergroup differences in the E/A ratio, especially when studying the effect of exercise training upon cardiac function.

The athlete's heart Part I (Review).

Importance of the athlete's heart has been arisen in the last decades.

Electron bunch length measurements from laser-accelerated electrons using single-shot THz time-domain interferometry.

Laser-plasma wakefield-based electron accelerators are expected to deliver ultrashort electron bunches with unprecedented peak currents. However, their actual pulse duration has never been directly measured in a single-shot experiment. We present measurements of the ultrashort duration of such electron bunches by means of THz time-domain interferometry. With data obtained using a 0.5 J, 45 fs, 800 nm laser and a ZnTe-based electro-optical setup, we demonstrate the duration of laser-accelerated, quasimonoenergetic electron bunches [best fit of 32 fs (FWHM) with a 90% upper confidence level of 38 fs] to be shorter than the drive laser pulse, but similar to the plasma period.

All-optical steering of laser-wakefield-accelerated electron beams.

We investigate the influence of a tilted laser-pulse-intensity front on laser-wakefield acceleration. Such asymmetric light pulses may be exploited to obtain control over the electron-bunch-pointing direction and in our case allowed for reproducible electron-beam steering in an all-optical way within an 8 mrad opening window with respect to the initial laser axis. We also discovered evidence of collective electron-betatron oscillations due to off-axis electron injection into the wakefield induced by a pulse-front tilt. These findings are supported by 3D particle-in-cell simulations.

Laser-driven shock acceleration of ion beams from spherical mass-limited targets.

We report on experimental studies of ion acceleration from spherical targets of diameter 15 microm irradiated by ultraintense (1x10(20) W/cm2) pulses from a 20-TW Ti:sapphire laser system. A highly directed proton beam with plateau-shaped spectrum extending to energies up to 8 MeV is observed in the laser propagation direction. This beam arises from acceleration in a converging shock launched by the laser, which is confirmed by 3-dimensional particle-in-cell simulations. The temporal evolution of the shock-front curvature shows excellent agreement with a two-dimensional radiation pressure model.

Chirped-pulse amplification of laser pulses with dispersive mirrors.

We report a novel implementation of chirped-pulse amplification (CPA) by dominantly using dispersive multilayer mirrors for chirp control. Our prototyp dispersive-mirror (DMC) compressor has been designed for a kHz Ti:sapphire amplifier and yielded--in a proof-of-concept study--millijoule-energy, sub-20-fs, 790-nm laser pulses with an overall throughput of approximately 90% and unprecedented spatio-temporal quality. Dispersive-mirror-based CPA permits a dramatic simplification of high-power lasers and affords promise for their advancement to shorter pulse durations, higher peak powers, and higher average powers with user-friendly systems.

Generation of stable, low-divergence electron beams by laser-wakefield acceleration in a steady-state-flow gas cell.

Laser-driven, quasimonoenergetic electron beams of up to approximately 200 MeV in energy have been observed from steady-state-flow gas cells. These beams emitted within a low-divergence cone of 2.1+/-0.5 mrad FWHM display unprecedented shot-to-shot stability in energy (2.5% rms), pointing (1.4 mrad rms), and charge (16% rms) owing to a highly reproducible gas-density profile within the interaction volume. Laser-wakefield acceleration in gas cells of this type provides a simple and reliable source of relativistic electrons suitable for applications such as the production of extreme-ultraviolet undulator radiation.

Observation of a strongly nested Fermi surface in the shape-memory alloy Ni0.62Al0.38.

The Fermi surface topology of the shape-memory alloy Ni0.62Al0.38 has been determined using Compton scattering. A large area of this Fermi surface can be made to nest with other areas by translation through a vector of approximately 0.18[1,1,0](2pi/a), which corresponds to the wave vector associated with martensitic precursor phenomena such as phonon softening and diffuse streaking in electron diffraction patterns. This observation is compelling evidence that these phenomena are driven by the enhanced electron-lattice coupling due to the Fermi surface nesting.

Direct observation of the multisheet Fermi surface in the strongly correlated transition metal compound ZrZn2.

The existence of flat areas of a Fermi surface (FS), predicted by electronic structure calculations and used in models of both magnetically mediated and phonon-mediated Fulde-Ferrell-Larkin-Ovchinnikov superconducting states, is reported in the paramagnetic phase of the ferromagnetic superconductor ZrZn2 using positron annihilation. The strongly mass-renormalized FS sheet, dominating the Fermi level density of states, is seen for the first time. The delocalization of the magnetization is studied using measured and calculated magnetic Compton profiles.