Fast Component Research Articles

Low-Temperature Emission Dynamics of Methylammonium Lead Bromide Hybrid Perovskite Thin Films at the Sub-Micrometer Scale.

We study the low-temperature (T = 4.7 K) emission dynamics of a thin film of methylammonium lead bromide (MAPbBr3), prepared via the anti-solvent method. Using intensity-dependent (over 5 decades) hyperspectral microscopy under quasi-resonant (532 nm) continuous wave excitation, we revealed spatial inhomogeneities in the thin film emission. This was drastically different at the band-edge (∼550 nm, sharp peaks) than in the emission tail (∼568 nm, continuum of emission). We are able to observe regions of the film at the micrometer scale where emission is dominated by excitons, in between regions of trap emission. Varying the density of absorbed photons by the MAPbBr3 thin films, two-color fluorescence lifetime imaging microscopy unraveled the emission dynamics: a fast, resolution-limited (∼200 ps) monoexponential tangled with a stretched exponential decay. We associate the first to the relaxation of excitons and the latter to trap emission dynamics. The obtained stretching exponents can be interpreted as the result of a two-dimensional electron diffusion process: Förster resonant transfer mechanism. Furthermore, the non-vanishing fast monoexponential component even in the tail of the MAPbBr3 emission indicates the subsistence of localized excitons. Finally, we estimate the density of traps in MAPbBr3 thin films prepared using the anti-solvent method at n∼1017 cm-3.

Pyro-phototronic effect coupled in self-powered, fast and broadband photodetector based on CIS/CTS heterojunction

The pyro-phototronic effect has been demonstrated as a successful approach to optimize the performance of heterojunction-based photodetector (PD) devices. Beyond the conventional restriction imposed by materials with intrinsic symmetry, pyroelectricity can be induced from the symmetry modulated at the interface of centrosymmetric components. Here, a self-powered PD based on cost-effective and eco-friendly p-type CuInS2 (CIS)/p-type Cu2SnS3 (CTS) nanocrystals (NCs) layers heterostructure is fabricated. By introducing the pyro-phototronic effect derived from the built-in electric field at the CIS/CTS interface, the PD realizes broadband detection in the ultraviolent (UV) (390 nm) to near infrared (NIR) (950 nm) range. The maximum responsivity and detectivity reach 9.053 mA/W and 5.05 × 1010 Jones for 390 nm illumination, 18.8 mA/W and 1.49 × 1011 Jones for 750 nm illumination and 42.5 mA/W and 6.507 × 1011 Jones for 950 nm illumination, at zero bias. These results show a ∼ 6-fold improvement, compared with those only based on the photovoltaic effect-induced photo-response (for 950 nm illumination). Upon 950 nm illumination, PD exhibits a fast photo-response component with rise time and fall time of 49.6 ms and 34.7 ms, respectively. This work offers a simple and promising approach to develop high-performance self-powered and broad-spectrum isotype heterojunction-based PDs (UV–vis-NIR) using the photovoltaic–pyroelectric coupled effect, while are no restricted to non-centrosymmetric materials.

Photodegradation of Flutamide and Halogen Derivatives of Nitrobenzotrifluoride: The NO Release Channel.

The photodegradation of the nonsteroidal antiandrogen drug flutamide has been long linked to the photoisomerization involving the nitro group. In this work, the dynamics of NO photoelimination upon photolysis at 266 nm of flutamide, nitrobenzotrifluoride, and its halogen derivatives were investigated. Similar to nitrobenzene and its derivatives, a bimodal translational energy distribution was observed for the NO photofragment indicating the presence of two distinct elimination channels resulting in slow and fast components. The trends in the slow/fast branching ratio show that halogen substitution at the para position increases the triplet state yield due to the internal heavy-atom effect leading to enhancement of the fast component. Furthermore, the topology of the triplet state potential energy surface showed that the minimum energy path favors the oxaziridine ring-type intermediate over the NO2 roaming mechanism in all five molecules investigated. The steric interaction between the NO2 group and the CF3 group, which are placed in the ortho position, lowers the barrier for the formation of the oxaziridine transition state compared to that of nitrobenzene.

Fast response 4f15d1→4f2 emission and host-to-impurity energy transfer in Pr3+ doped Na3LuSi3O9 double salt silicate

Understanding of host-to-impurity energy transfer process is crucial for the development of efficient and fast response scintillator materials. In this work, Pr3+ doped Na3LuSi3O9 (NLS) double salt silicate has been successfully synthesized using a high temperature solid-state reaction method and further comprehensively characterized by means of XRD measurements, crystal structure refinement, luminescence spectroscopic and time-domain study upon VUV-UV and X-ray synchrotron excitation, and thermally stimulated luminescence (TSL) study. Based on these results a model of host to Pr3+ 4f15d1 and 4f2 has been proposed. It has been demonstrated that NLS:Pr3+ has a good potential for fast response scintillator applications due to the presence of an efficient energy transfer from host electronic excitations to Pr3+ 4f15d1 states. The Pr3+ 4f15d1→4f2 emission reveals a good thermal stability and is characterized by a lifetime of about 16 ns. Upon pulse X-ray excitation the main fast decay component is accompanied by slower one with lifetime of about 64 ns that is ascribed to the presence of shallow traps which retrap carriers and cause appearance of delayed recombination. Parameters for the corresponding traps have been calculated based on the TSL glow curve analysis.

Influence of the microenvironment dynamics of tryptophan on its fluorescence parameters at different temperatures

The temperature dependences of the fast and slow fluorescence decay components of aqueous solution of tryptophan molecules after freezing to -170°C - 20°C under actinic light and in the dark were investigated. A model of the direct and reverse electronic transitions from an excited state to the ground state and to the state with charge transfer for a tryptophan molecule was used to perform quantitative analysis. Three main spectral regions of tryptophan fluorescence are shown, they differ in the behavior of the temperature dependences depicted for the rates of transition from the excited state of tryptophan to the state with charge transfer. It has been shown that the dynamics of the hydrogen bonded system plays a key role in this transition. The system of hydrogen bonding determines the nonlinear nature in tryptophan fluorescence in the selected spectral regions. The non-linear behavior of the fluorescence lifetime and fluorescence spectra with temperature change is determined by the type of the interaction of tryptophan with water and ice. It has been found that temperature rearrangements play a critical role in hydrogen bonding structure of H2O 2 that surrounds a tryptophan molecule in the excited state.

Reduction of PSII photosynthetic performance by low temperature is the reason for the growing inhibition of Kobresia pygmaea Clarke

AbstractKobresia pygmaea Clarke is mainly distributed in the alpine region from 3800 to 4500 m elevation on the Qinghai-Tibet Plateau. It is excellent in low-temperature tolerance and trampling resistance and plays an important role in maintaining the stability of regional ecological environments. Mainly based on the chlorophyll fluorescence imaging technique, using grass sods blocks with a size of 20 × 20 cm2 collected from K. pygmaea forb meadow, simulated a low-temperature treatment in cultural room with 8 °C/4 °C (day/night) at diurnal photoperiod, we analyzed the effects of low temperature on PSII photochemical efficiency and non-photochemical quenching, as well as the interaction between low temperature and light intensity. The results showed that low temperature could significantly decrease the maximum quantum efficiency of PSII photochemistry (Fv/Fm) and inhibit the leaf growth of K. pygmaea. The light response curve of PSII relative linear electron transport rate was reduced by low temperature, while it recovered to almost normal level after two days of removing adversity. Further experiments under steady-state actinic light confirmed that light intensity was the main factor affecting the PSII photochemical efficiency, and its reduction caused by the low temperature showed a certain degree of reversibility. The non-photochemical quenching (NPQ) was significantly affected by light intensity, and its fast and slow components (NPQf and NPQs) in NPQ accounted for 36% and 64% of NPQ, respectively. The decrease in NPQf and corresponding increase in NPQs slowly recovered after relieving from low-temperature condition. The relative inhibition of photosynthesis (Pinh) was significantly enhanced by low temperature and reduced after removal of adversity. Strong light intensity could intensify the adverse effect of low temperature on PSII operating efficiency Fq′/Fm′ and efficiency factor Fq′/Fv′, as well as NPQ. In conclusion, low temperature was one of the main reasons limiting the photosynthetic performance of K. pygmaea on the Qinghai-Tibet Plateau and could aggravate photosynthetic photoinhibition. The adversity of low temperature frequently occurring in the plant growing season on the Qinghai-Tibet Plateau was constituted of the main factor of the low productivity level in alpine meadow.

Decay behavior of Eu2+-Activated sulfide phosphors: The Pivotal role of unique activator sites

We present a systematic decay analysis of four sulfide phosphors, namely SrS:Eu2+, CaAl2S4:Eu2+, KGaS2:Eu2+, and NaBaAlS3:Eu2+. In SrS and NaBaAlS3, there is only one activator site, whereas KGaS2 has two, and CaAl2S4 has three. We confirm the typical concentration quenching behavior, where the decay rate increases with the Eu2+ activator concentration. The decay curve for these sulfide phosphors consists of two components. The fast decay component remains unaffected by the Eu2+ activator concentration, while the slow component exhibits the typical concentration quenching behavior. The initial sharp decline in the decay curve, which is concentration-independent, is associated with direct quenching occurring in close proximity to the excited activator before inter-activator energy transfer takes place. The subsequent concentration quenching results from active inter-activator energy transfer. An intriguing observation is termed “wavelength quenching”, where the decay rate increases as the emission probe wavelength decreases. This phenomenon is active for multi-site phosphors but inactive for single-site phosphors, which can be attributed to the active inter-activator energy transfer between distinct crystallographic sites within the host.

Balancing EC‐Earth3 Improving the Performance of EC‐Earth CMIP6 Configurations by Minimizing the Coupling Cost

AbstractEarth System Models (ESMs) are complex systems used in weather and climate studies generally built from different independent components responsible for simulating a specific realm (ocean, atmosphere, biosphere, etc.). To replicate the interactions between these processes, ESMs typically use coupling libraries that manage the synchronization and field exchanges between the individual components, which run in parallel as a Multi‐Program, Multiple‐Data application. As ESMs get more complex (increase in resolution, number of components, configurations, etc.), achieving the best performance when running in High‐performance Computing platforms has become increasingly challenging and of major concern. One of the critical bottlenecks is the load‐imbalance, where the fastest components will have to wait for the slower ones. Finding the optimal number of processing elements to assign to each of the multiple independent constituents to minimize the performance loss due to synchronizations and maximize the overall parallel efficiency is impossible without the right performance metrics, methodology, and tools. This paper presents the results of balancing multiple Coupled Model Intercomparison Project phase 6 configurations for the EC‐Earth3 ESM. We will show that intuitive approaches can lead to suboptimal resource allocations and propose new setups up to 25% fasters while reducing the computational cost by 72%. We prove that new methods are needed to deal with the load‐balance of ESMs and hope that our study will serve as a guide to optimize any other coupled system.

Control for a Class of Two-Time-Scale Cyber-Physical Systems: An Asynchronous Dynamic Event-Triggered Protocol.

In this article, the control problem is investigated for a class of two-time-scale cyber-physical systems (TTSCPSs). In order to reduce the network bandwidth occupation and lighten the computation burden, an asynchronous dynamic event-triggered protocol (ADETP) is designed to arrange the signal transmissions from sensors to the composite controllers, in which the triggering sequences of fast and slow system components are determined separately. A novel composite controller based on the proposed ADETP is designed dependent on the singular perturbation parameter (SPP) such that the closed-loop TTSCPS is asymptotically stable with meeting a required performance index when the SPP is no more than a given upper bound. Gain matrices of the desired composite controller are parameterized in terms of the solutions to certain matrix inequalities that are readily solvable. Finally, simulation results of a nuclear reactor are presented to verify the effectiveness of the proposed approach.

A numerical approach to model sound generation by ocean dynamical processes: The case of surface gravity waves.

The new generation of regional ocean models can provide the evolution of both the slow and fast components of pressure, consequently opening original opportunities to evaluate the acoustic signal generated by ocean slower dynamical processes. This capacity is evaluated in the case of surface waves, with a focus on the hydro-acoustic precursors and on the acoustic modes induced by supersonic surface wave groups. The consistency with theory confirms that such models are adapted to answer recent interrogations by Wunsch [(2022). J. Acoust. Soc. Am. 152(4), 2160-2168] about evaluating the noise of ocean processes.

Spectral and temporal properties of 5-phenyl-2-[4-(5-phenyl-1,3-oxazol-2-yl)phenyl]-1,3-oxazole (POPOP) multiphoton-excited luminescence

The results of a study of multiphoton-excited luminescence and Stimulated Raman scattering (SRS) of POPOP in a form of crystalline powder and toluene solution are presented. Two-photon and three-photon-excited luminescence in POPOP crystalline powder and toluene solution was registered under excitation by pico- and nanosecond laser pulses. Samples cooling to the temperature of liquid nitrogen leads to the appearance of an additional line in the luminescence spectrum at a wavelength of 447 nm, SRS lines intensity increasing accompanying two-photon luminescence process and changing temporal dynamics, a decrease in the contribution of the fast component in the decay time curve.

Asymptotic behavior of multiscale stochastic partial differential equations with Hölder coefficients

In this paper, we establish a quantified asymptotic analysis for a semi-linear slow-fast stochastic partial differential equation with Hölder coefficients. By studying the Poisson equation in Hilbert space, we first prove the strong convergence in the averaging principle, which is viewed as a functional law of large numbers. Then we study the stochastic fluctuations between the original system and its averaged equation. We show that the normalized difference converges weakly to an Ornstein-Uhlenbeck type process, which is viewed as a functional central limit theorem. Rates of convergence both for the strong convergence and the normal deviation are obtained, and these convergences are shown not to depend on the regularity of the coefficients in the equation for the fast variable, which coincides with the intuition, since in the limit systems the fast component has been totally averaged or homogenized out.

Low Complex CORDIC-based Hand Movement Recognition Design Methodology for Rehabilitation and Prosthetic Applications.

Hand movement recognition using Electromyography (EMG) signals have gained much significance lately and is extensively used for rehabilitation and prosthetic applications including stroke-driven disability and other neuromuscular disorders. Herein, quantitative analysis of EMG signals is very crucial. However, such applications are constrained by power consumption limitations due to the battery backup necessitating low-complex system design and the on-chip area requirement. Existing hand movement recognition methodologies using single-channel EMG signal involve computationally intensive stages, including Ensemble Empirical Mode Decomposition (EEMD), Fast Independent Component Analysis (FastICA), feature extraction, and Linear Discriminant Analysis (LDA) classification, which can not be mapped onto the low-complex architecture directly from the algorithmic level. The high computational complexity of LDA classification makes it difficult to be used for low-complex applications. In this paper, we introduce a low-complex CORDIC-based hand movement recognition design methodology targeting resource-constrained rehabilitation applications. This work explores replacing LDA classification with K-Means clustering due to its reduced complexity and efficient clustering algorithm. CORDIC-based K-Means clustering is used to further reduce the overall computational complexity of the system. The proposed low complex, K-Means clustering-based hand movement recognition for classifying seven hand movements using single-channel EMG data is found to be 99.77 % less complex and 1.28% more accurate than the conventional LDA-based classification.

Hydrothermal crystal growth of tetralithium octafluoridozirconate (Li4ZrF8) and its physicochemical properties

A single crystal of tetralithium octafluridozirconate (Li4ZrF8) has been obtained by using a hydrothermal process. The crystal phase was analyzed using a powder X-ray diffraction pattern and matched with standard reference data. The high-resolution X-ray diffraction curve indicates that the crystal has good crystalline perfection. The thermal behavior of the crystal sample was investigated by TGA/DSC analysis. The optical bandgap of the crystal sample was calculated from the Tauc plot and found to be 5.8 eV. The crystal sample exhibits intrinsic X-ray excited luminescence with a peak maximum of 265 nm. The thermoluminescence measurement shows two peaks, one is at the high-temperature region of 545 K and another one is at the low-temperature region at 383 K. TL kinetic parameters such as activation energy (E) and frequency factor (s) for the peak at 545 K was estimated as 1.20 eV and 2.06 × 10−10 respectively. The sample has good TL sensitivity to the neutron dose in the order of µsv. The low-temperature thermoluminescence measurements were carried out to study the trap levels and found two major glow peaks at 108 and 130 K. Scintillation properties were analyzed under α-rays from a 241Am source. The decay time profile was well fitted with three components and the fitted values show the fast component of 500 ns (9 %), the medium component of 2.4 μs (24 %), and a slow component of 12.8 μs (67 %).

Topological Comparison of Some Dimension Reduction Methods Using Persistent Homology on EEG Data

In this paper, we explore how to use topological tools to compare dimension reduction methods. We first make a brief overview of some of the methods often used in dimension reduction such as isometric feature mapping, Laplacian Eigenmaps, fast independent component analysis, kernel ridge regression, and t-distributed stochastic neighbor embedding. We then give a brief overview of some of the topological notions used in topological data analysis, such as barcodes, persistent homology, and Wasserstein distance. Theoretically, when these methods are applied on a data set, they can be interpreted differently. From EEG data embedded into a manifold of high dimension, we discuss these methods and we compare them across persistent homologies of dimensions 0, 1, and 2, that is, across connected components, tunnels and holes, shells around voids, or cavities. We find that from three dimension clouds of points, it is not clear how distinct from each other the methods are, but Wasserstein and Bottleneck distances, topological tests of hypothesis, and various methods show that the methods qualitatively and significantly differ across homologies. We can infer from this analysis that topological persistent homologies do change dramatically at seizure, a finding already obtained in previous analyses. This suggests that looking at changes in homology landscapes could be a predictor of seizure.

White‐light emission and red scintillation from Mn2+ ions single‐doped aluminum‐silicate glasses

AbstractA series of Mn2+ single‐doped 0.2Gd2O3‐0.2Al2O3‐0.6SiO2 (GAS: xMn2+) glasses with Si3N4 as reducing agent were prepared. The presence of [SiO4‐x] defects and Mn2+ ions was determined from the absorption and excitation spectra of the glasses. With the increase of Mn2+ concentration, the intensity of blue emission decreases, while the intensity of red emission increases. The color coordinate of GAS: 6Mn2+ glass is (0.264, 0.226). The lifetime of the glasses was tested. Under the monitoring of 440 nm, the fast components (τf) are between 17 and 85 μs, and the slow components (τs) are between 200–650 μs. The former belongs to [SiO4‐x] defects, and the latter is [4E(G), 4A1(G)]→6A1(S) transition of Mn2+ ions. Under the monitoring at 630 nm, the τf are between 110 and 300 μs, and the τs are between 680 and 1220 μs, which are due to 4T1(G)→6A1(S) transition of Mn2+ ions and Mn2+ pairs, respectively. The energy transfer mechanism of [SiO4‐x] defect→Mn2+ ions are explained. The efficient [SiO4‐x] defect →Mn2+ ions energy transfer process was demonstrated by time‐resolved photoluminescence, and the energy transfer efficiency is over 85%. The maximum photoluminescence quantum yield (PL QY) of the glasses can reach 15.87%. The thermal activation energy of the glasses was calculated. In addition, X‐ray excited red luminescence spectra and the mechanism of the glasses were investigated.

Steady-state and dynamic characteristics of deep UV luminescence in rock salt-structured MgxZn1−xO

Temperature-dependent cathodoluminescence spectra were measured for rock salt-structured MgxZn1−xO films with x = 0.95–0.61. The Mg0.95Zn0.05O film exhibited the shortest deep UV peak wavelength of 199 nm (6.24 eV) at 6 K. Relatively high equivalent internal quantum efficiencies of 0.9%–11% were obtained. The Tauc plots, which were obtained from temperature-dependent optical transmittance measurements, exhibited large Stokes-like shifts of 0.7–0.9 eV at 6–300 K. Time-resolved photoluminescence (PL) signals at 7 K exhibited fast and slow decay components. The fast decay component had PL lifetimes of 2.59–3.08 ns, and the slow decay component far exceeded the measurement time range of 12.5 ns. The fast decay constant reflected the transfer lifetime of the photoexcited carriers to certain trapping centers. These centers were tentatively ascribed to Zn-related isoelectronic trapped-hole centers and may be a cause of the large Stokes-like shifts. The signals at 300 K exhibited very short PL lifetimes of 120–180 ps. The PL lifetimes were mainly attributed to the nonradiative recombination lifetime. Simultaneous decreases in the Zn-related isoelectronic trapped-hole centers and the nonradiative recombination centers were found to be necessary to improve the DUV emission properties of RS-MgxZn1−xO films.

Fast Ce,Ca:LuAG scintillation ceramics for HEP: Fabrication, characterization, and computation

AbstractHigh‐energy physics community is looking for a hard, fast, and low‐cost scintillation material, and Ce:Lu3Al5O12 (Ce:LuAG) ceramic is one of the competitive candidates. This work presents Ce,Ca:LuAG scintillation ceramics with good optical quality, and the influence of Ce and Ca concentrations on optical and scintillation properties was fully analyzed. At relatively low level of Ce concentration, the less Ca2+ content is needed to achieve a significant intensity increase in fast scintillation component while maintaining a relatively high light yield (LY). The introduction of only 0.1 at% Ca2+ could increase the LY0.5 μs/LY3.0 μs from 79.9% to 96.1% in Ce,Ca:LuAG ceramics of 0.1 at% Ce. First‐principles investigations are further performed to reveal the tuning mechanisms of the scintillation properties of LuAG by Ce and Ca codoping. We show that the Fermi level shifts down with Ca codoping, which increases the Ce4+ content and decreases the depth of the electron traps (VO), resulting to a faster decay. Moreover, the formation preference of Ca‐VO complexes over Ce‐VO leads to the suppression of the non‐radiative decay of Ce via VO. In summary, our study demonstrates the realization of the performance tuning of LuAG via Ce and Ca codoping.

An Energy Budget Framework to Understand Mechanisms of Land–Ocean Warming Contrast Induced by Increasing Greenhouse Gases. Part II: Transient Climate State

Abstract We investigate the land–ocean warming contrast mechanisms, ϕ, defined as the land-mean surface air temperature (SAT) change divided by the ocean-mean SAT change, in a transient climate response (TCR) obtained from the Coupled Model Intercomparison Project phase 6 (CMIP6) 1% per year CO2 increase experiments (1pctCO2). The energy budget framework devised in Part I is applied to 15 CMIP6 1pctCO2 simulations, and the climate response in year 140 when the CO2 concentration was quadrupled was compared with a near-equilibrium climate response (NEQ), defined as the last 30-yr mean in the abrupt CO2 quadrupling (abrupt4×CO2) experiments. It is shown that ϕ is larger in TCR than in NEQ by approximately 4%, although the difference is not statistically significant. In TCR, effective radiative forcing is large over land compared to the ocean, and this is the main contributor to ϕ as in NEQ. The time evolution of ϕ in 1pctCO2 can be reconstructed by means of the fast and slow components of climate response in abrupt4×CO2, indicating that the essential mechanism for the land–ocean warming contrast shown in Part I applies to TCR. Furthermore, our analyses reveal a compensation between land-to-ocean atmospheric energy transport that decreases ϕ and ocean heat uptake that increases ϕ. Regardless of the time scale of the response, these two processes are linked by the change in atmospheric circulation, leading to the small combined effect. As a result, the multimodel mean ϕ in 1pctCO2 is roughly time invariant at approximately 1.5 despite the continuous increase in CO2. Significance Statement The land–ocean warming contrast, which indicates large land surface warming compared to ocean surface warming in response to an increase in atmospheric CO2 concentration, is a striking feature of human-induced global warming. This study focuses on temporal changes in the magnitude of the land–ocean warming contrast in transient climate change simulations and shows that the magnitude of the land–ocean warming contrast is nearly constant over time, maintaining a ratio of approximately 1.5, between land and ocean surface warming. This small temporal change is explained mainly by a compensation between land-to-ocean energy transport and ocean heat uptake, because both act in opposite directions to the land–ocean warming contrast.

Physiological and Energetic Demands During Still-Rings Routines of Elite Artistic Gymnasts.

The aim of the study was to analyze physiological and energetic demands of elite gymnasts during still-rings routines (SRRs). Eleven male gymnasts (mean [SD] 23.6 [3.9]y, 65.9 [5.6]kg, 171.1 [6.7]cm) performed a maximal graded exercise test and an individual SRR, during which respiratory gas and heart rate (HR) were measured using a mobile spiroergometer and a paired HR sensor. Metabolic energy and the energy contribution in terms of aerobic, anaerobic lactic, and anaerobic alactic were determined by oxygen uptake (VO2) during exercise, net lactate production, and the fast component of postexercise VO2 kinetics. Mean routine duration of the SRRs was 48.3 (4.5)seconds. VO2 and HR during SRRs were shown to be 86.9% (5.9%) and 91.0% (3.3%), respectively, of the maximal values measured during the graded exercise test. The anaerobic alactic, aerobic, and anaerobic lactic systems provided 50.9% (6.6%), 28.6% (4.8%), and 20.5% (5.2%), respectively, of the total energy required during SRRs. The energy contribution of the anaerobic lactic system correlated negatively with individual anaerobic threshold (r = -.715) and maximal VO2 (r = -.682). The anaerobic alactic system is the predominant energy source for ATP resynthesis during SRRs. The high relative VO2 and HR values reached during SRRs showthat these routines strongly stress the cardiovascular system.