Split Times Research Articles

Resisted sprint training with partner towing improves explosive force and sprint performance in young soccer players - a pilot study.

The purpose of this study was to examine the effects of non-resisted (NRS) and partner-towing resisted (RS) sprint training on legs explosive force, sprint performance and sprint kinematic parameters. Sixteen young elite soccer players (age 16.6 ± 0.2 years, height 175.6 ± 5.7 cm, and body mass 67.6 ± 8.2 kg) were randomly allocated to two training groups: resisted sprint RS (n = 7) and non-resisted sprint NRS (n = 9). The RS group followed a six-week sprint training programme consisting of two “sprint training sessions” per week in addition to their usual soccer training. The NRS group followed a similar sprint training programme, replicating the distances of sprints but without any added resistance. All players were assessed before and after training: vertical and horizontal jumping (countermovement jump (CMJ), squat jump (SJ), and 5-jump test (5JT)), 30 m sprint performance (5, 10, and 20 m split times), and running kinematics (stride length and frequency). In the RS group significant (p < 0.05) changes were: decreased sprint time for 0–5 m, 0–10 m and 0–30 m (-6.31, -5.73 and -2.00%; effect size (ES) = 0.70, 1.00 and 0.41, respectively); higher peak jumping height (4.23% and 3.59%; ES = 0.35 and 0.37, for SJ and CMJ respectively); and 5JT (3.10%; ES = 0.44); and increased stride frequency (3.96%; ES = 0.76). In the NRS group, significant (p < 0.05) changes were: decreased sprint time at 0–30 m (-1.34%, ES = 0.33) and increased stride length (1.21%; ES = 0.17). RS training (partner towing) for six weeks in young soccer players showed more effective performances in sprint, stride frequency and lower-limb explosive force, while NRS training improved sprint performance at 0–30 m and stride length. Consequently, coaches and physical trainers should consider including RS training as part of their sprint training to ensure optimal sprint performance.

Time splitting combined with exponential wave integrator Fourier pseudospectral method for quantum Zakharov system

&lt;p style='text-indent:20px;'&gt;In this paper we develop a time splitting combined with exponential wave integrator (EWI) Fourier pseudospectral (FP) method for the quantum Zakharov system (QZS), i.e. using the FP method for spatial derivatives, a time splitting technique and an EWI method for temporal derivatives in the Schrödinger-like equation and wave-type equations, respectively. The scheme is fully explicit and efficient due to fast Fourier transform. Numerical experiments for the QZS are presented to illustrate the accuracy and capability of the method, including accuracy tests, convergence of the QZS to the classical Zakharov system in the semi-classical limit, soliton-soliton collisions and pattern dynamics of the QZS in one-dimension, as well as the blow-up phenomena of QZS in two-dimension.&lt;/p&gt;

Simulação Numérica de Inundações em Casos de Rompimento de Barragem

Water is a fundamental resource for the development of society, attracting communities since the beginning of civilization. This proximity of civilizations to water resources has demanded strategies for better water management, such as the construction of dams, subjecting ecosystems to more serious problems. In this paper, the shallow water equations are solved numerically by the finite element method and the characteristic‐based split scheme, in space and time, respectively. The model’s used to simulate dam-break cases from literature, in wet bed without obstacles and with solid obstacles. The results obtained are in accordance with the publications, validating the adopted methodology. Finally, the numerical simulations make it possible to know the occurrence of dam-break flow, generating information about the occurrence of this kind of disastrous event.

Proactive Project Scheduling With Activity Splitting and Resource Transfer Times Under Uncertain Environments

Proactive project scheduling aims to generate robust baseline schedules that are protected against the potential schedule disruptions during project execution. In this paper, we propose a new problem named the proactive resource-constrained project scheduling problem with activity split-ting and resource transfer times, and try to investigate the trade-off between the benefits of activity splitting and the drawbacks of the resulting more resource transfer times. The proposed problem is formulated into an integer programming model with considering the constraints of a maximum allowed number of splitting and a minimum period of continuous execution. Since the problem is NP-hard in the strong sense, a genetic algorithm is then developed for problem solving. From the obtained results of a designed computational experiment, we prove that the developed genetic algorithm is effective in solving the defined problem, and the benefits of activity splitting to schedule robustness improvement can be weaken with the resulting more resource transfer times among the subactivities. Besides, with the increase of the maximum allowed number of activity splitting, the decrease of the minimum continuous execution time, the decrease of resource transfer times, and the extension of project deadlines, schedule robustness increases.

Partially Implicit FDTD (PI-FDTD) Method for Lower Dispersion and Anisotropic Errors

A new partially implicit 3D FDTD (PI-FDTD) method is introduced. The method is not unconditionally stable, but its stability limit is 6 times higher than that of the classic Yee&#x2019;s FDTD method. The method has only one implicit update equation and uses four split time steps. A study has been carried out to compare the performances of the new method and the ADI-FDTD, LOD-FDTD, and HIE-FDTD methods. ADI-FDTD and LOD-FDTD methods are unconditionally stable and the HIE-FDTD method is conditionally stable with a stability limit of 3.46 times above the Yee&#x2019;s FDTD method. The dispersion and anisotropic errors of the PI-FDTD method are considerably lower than that of these methods and for small cell sizes, the new method is almost isotropic. For example at the stability limit of the PI-FDTD method with a uniform cell size of <inline-formula> <tex-math notation="LaTeX">$\lambda \mathord {\left /{ {{ {50}}} }\right. }$ </tex-math></inline-formula> the maximum dispersion errors and anisotropic errors are 0.15&#x0025; and 0.031&#x0025; for the new method and 1.66&#x0025; and 0.64&#x0025; for the ADI-FDTD and LOD-FDTD methods. At the stability limit of the HIE-FDTD method, the maximum dispersion errors and anisotropic errors of the PI-FDTD method are also less than HIE-FDTD, ADI-FDTD, and LOD-FDTD methods. The differences in errors are more pronounced for larger cell sizes. Although the new method uses a four time split step scheme and the ADI-FDTD and LOD-FDTD methods use a two time split step scheme, the computational time of the PI-FDTD method is less, as it uses an implicit scheme for only one of the field components when updating. The computational time of the PI-FDTD method is the same as that of the HIE-FDTD method. The study has revealed that the new method can be used over much wider frequency bandwidths.

Field Trial Assessing the Use of Sex-Sorted Semen in Beef Cattle

Objective: The objective was to evaluate the reproductive performance of sex-sorted semen on beef cows and heifers. Study Description: For this trial, 320 Angus and SimAngus cows and heifers from four groups were used. Group 1 yearling heifers (n = 101) were synchronized using the melengestrol acetate plus prostaglandin F2α (MGA-PGF2α) protocol and Groups 2, 3, and 4 cows (n = 219) were synchronized using the 7-Day CO-Synch + CIDR protocol. Insemination was done with semen from an Angus sire (Group 1 yearling heifers and Group 2 young cows) sorted to contain >90% X-bearing sperm, or a Charolais sire (Groups 3 and 4 mature cows) sorted to contain >90% Y-bearing sperm. Females were bred after visual estrus detection (Group 1 yearling heifers), fixed time artificial insemination (AI; Group 4 mature cows), or split time AI (Group 2 young cows and Group 3 mature cows). The Bottom Line: These results indicate that sex-sorted semen has potential in commercial beef cows and heifers. Increasing carcass weights in the beef industry has caused a greater price spread between steers and heifers. With increasing spread in value between heifer calves and steer calves, opportunity exists for economic gain with “bull” sexed semen, especially in terminal sire programs.

Human mitochondrial DNA diversity is compatible with the multiregional continuity theory of the origin of Homo sapiens

Confidence intervals for estimates of human mtDNA sequence diversity, chimpanzee-human mtDNA sequence divergence, and the time of splitting of the pongid-hominid lineages are presented. Consistent with all the data used in estimating the coalescence time for human mitochondrial lineages to a common ancestral mitochondrion is a range of dates from less than 79,000 years ago to more than 1,139,000 years ago. Consequently, the hypothesis that a migration of modern humans (Homo sapiens) out of Africa in the range of 140,000 to 280,000 years ago resulted in the complete replacement, without genetic interchange, of earlier Eurasian hominid populations (Homo erectus) is but one of several possible interpretations of the mtDNA data. The data are also compatible with the hypothesis, suggested earlier and supported by fossil evidence, of a single, more ancient expansion of the range of Homo erectus from Africa, followed by a gradual transition to Homo sapiens in Europe, Asia, and Africa.

World and European Rowing Medallists Pace With Smaller Variation Than Their Competitors.

Purpose: To establish the relation between pacing pattern and performance, within sex, and number of crew members, at the very highest performance level in World class rowing.Methods: Pacing profiles based on official 500 m split times in 106 A-finals with six contesting boat crews (n = 636 crews), in recent World (2017–2019) and European (2017–2021) championships, were analyzed. The coefficient of variation (CV) and sum of relative differences (SRD) of the split times, and normalized velocities in the four segments of the race, were compared between performance levels, that is, placement (1st–6th), and subgroups based on sex (female or male) and number of crew members (one, two, or four). Statistical tests and resulting p-values and effect sizes (Cohen's d) were used to assess differences between groups.Results: The pacing profiles of the medallists had smaller variation than those of the non-podium finishers (CV = 1.72% vs. CV = 2.00%; p = 4 × 10−7, d = 0.41). Compared to the non-podium finishers, the medallists had lower normalized velocities in the first and second segments of the race, slightly higher in the third segment and higher in the fourth segment. Female crews paced somewhat more evenly than male crews. No significant differences were found in the evenness of pacing profiles between singles, doubles/pairs and quads/fours. Analyses of SRD were overall consistent with analyses of CV.Conclusion: Medal winners in major rowing championships use a more even pacing strategy than their final competitors, which could imply that such a strategy is advantageous in rowing.

Ps-splitting analysis reveals differential crustal deformation beneath the Qinling Orogenic Belt and its surrounding areas

SUMMARYCrustal anisotropy parameters beneath the Qinling Orogenic Belt (QOB) and its surrounding areas (including the northeastern Tibetan Plateau) are investigated by harmonic fitting the arrival times of the P-to-S converted phase from the Moho and an intracrustal discontinuity. The measurements reveal strong and spatially varying crustal anisotropy beneath the study region, with an average splitting time of 0.50 ± 0.17 s. The eastern Kunlun Orogen (EKLO), western part of QOB (WWQL) and Longmenshan block (LMB) present relatively larger crustal anisotropy, and the fast orientations changed gradually from NWW–SEE in EKLO and WWQL to NEE–SWW in LMB. The crustal anisotropy measurements, combined with the results from ambient-noise tomography and gravity inversion, suggest that the middle-lower crustal flow induced by the inhomogeneous crustal thickening during the early stage of plateau growth exists beneath these areas. The fast orientations beneath the eastern part of the QOB are predominantly NNE–SSW, nearly orthogonal to that from local shear wave splitting and teleseismic XKS splitting. The crustal anisotropy measurements suggest a layered deformation beneath the eastern QOB. The upper crust retains the fossil deformation formed during the main orogeny, the middle-to-lower crust is dominated by the N–S oriented subduction, collision and continued convergence between the North China Block, South China Block and Qinling microblocks; the upper mantle is decoupled from the crust and mainly controlled by the mantle flow from the Tibetan Plateau.

Throughput performance for full-duplex DF relaying protocol in hybrid wireless power transfer systems

Most of the existing studies on energy harvesting (EH) cooperative relaying networks are conducted for the outdoor environments which are mainly characterized by Rayleigh fading channels. However, there are not as many studies that consider the indoor environments whereas the state-of-the-art internet of things (IoT) and smart city applications are built upon. Thus, in this paper, we analyze a namely hybrid time-power splitting relaying (HTPSR) protocol in a full-duplex (FD) decode-and-forward (DF) battery-energized relaying network in indoor scenarios modelled by the unpopular log-normal fading channels. Firstly, we formulate the analytical expression of the outage probability (OP) then the system throughput. Accordingly, we simulate the derived expressions with the Monte Carlo method. It is worth mentioning that in our work, the simulation and the theory agree well with each other. From the simulation results, we know how to compromise either the power splitting (PS) or the time splitting (TS) factors for optimizing the system performance.

Spectrum efficiency maximization for cooperative power beacon-enabled wireless powered communication networks

We consider a spectrum efficiency (SE) maximization problem for cooperative power beacon-enabled wireless powered communication networks (CPB-WPCNs), where each transmitter harvests energy from multi-antenna power beacons (PBs) and transmits data to the corresponding receiver. For data transmission, both orthogonal transmission, i.e., the time splitting (TS) mode, and non-orthogonal transmission, i.e., the interference channel (IC) mode, are considered. Aiming to improve the system SE, the energy beamformers of PBs, the transmit power, and the transmit time duration of transmitters are jointly optimized. For the TS mode, the original non-convex problem is transformed into a convex optimization problem by means of variable substitution and semidefinite relaxation (SDR). The rank-one nature of this SDR is proved, and then a Lagrange-dual based fast algorithm is proposed to obtain the optimal solution with much lower complexity. For the IC mode, to conquer the strong non-convexity of the problem, a branch-reduce-and-bound (BRB) monotonic optimization algorithm is designed as a benchmark. Furthermore, a low-complexity distributed successive convex approximation (SCA) algorithm is presented. Finally, simulation results validate the performance of the proposed algorithms, achieving optimality within only 1%∼2% computation time compared to the CVX solver in the TS mode and achieving 98% of the optimal performance in the IC mode.

Dual-Hop Underwater Optical Wireless Communication System With Simultaneous Lightwave Information and Power Transfer

The most significant challenge of underwater optical wireless communication (UOWC) system is to overcome its limited coverage. To expand the achievable communication range, we investigate the performance of the dual-hop UOWC system with simultaneous lightwave information and power transfer (SLIPT). The time splitting (TS) method is adopted for wireless power transfer in the proposed system, where the information and energy are transmitted in different phases. A suitable transmission strategy is designed for the model without additional power supply, which contains three phases, i.e. information transmission, energy transmission, and forwarding process. The expressions of the average bit error rate (BER) at the target node and the energy harvested by the relay node are derived over underwater attenuation channel. Then, the effects of the TS factor and the distances on the system performance are investigated in two sub-problems, which minimize the average BER while satisfying the energy harvesting and transmitting rate constraints. Numerical results indicate the performance improvement by adopting the relay node with SLIPT.

Mantle Structure and Flow Across the Continent‐Ocean Transition of the Eastern North American Margin: Anisotropic S‐Wave Tomography

AbstractLittle has been seismically imaged through the lithosphere and mantle at rifted margins across the continent‐ocean transition. A 2014–2015 community seismic experiment deployed broadband seismic instruments across the shoreline of the eastern North American rifted margin. Previous shear‐wave splitting along the margin shows several perplexing patterns of anisotropy, and by proxy, mantle flow. Neither margin parallel offshore fast azimuths nor null splitting on the continental coast obviously accord with absolute plate motion, paleo‐spreading, or rift‐induced anisotropy. Splitting measurements, however, offer no depth constraints on anisotropy. Additionally, mantle structure has not yet been imaged in detail across the continent‐ocean transition. We used teleseismic S, SKS, SKKS, and PKS splitting and differential travel times recorded on ocean‐bottom seismometers, regional seismic networks, and EarthScope Transportable Array stations to conduct joint isotropic/anisotropic tomography across the margin. The velocity model reveals a transition from fast, thick, continental keel to low velocity, thinned lithosphere eastward. Imaged short wavelength velocity anomalies can be largely explained by edge‐driven convection or shear‐driven upwelling. We also find that layered anisotropy is prevalent across the margin. The anisotropic fast polarization is parallel to the margin within the asthenosphere. This suggests margin parallel flow beneath the plate. The lower oceanic lithosphere preserves paleo‐spreading‐parallel anisotropy, while the continental lithosphere has complex anisotropy reflecting several Wilson cycles. These results demonstrate the complex and active nature of a margin which is traditionally considered tectonically inactive.

Current Barriers in Robotic Surgery Training for General Surgery Residents

To assess the current barriers in robotic surgery training for general surgery residents. Multi-institutional web-based survey. 9 academic medical centers with a general surgery residency. General surgery residents of at least PGY-3 training level. 163 general surgery residents were contacted with 80 responses (49.1%). The most common responders were PGY-3s (38.8%) followed by PGY-5s (27.5%). The Northeast represented 42.5% of responses. Colorectal cases were the most common robotic case residents were involved in (51.3%). Residents' typical roles were assisting at the bedside (31.3%) and splitting time between assisting at the bedside and operating at the surgeon console (31.3%). 43% report to be either extremely or somewhat dissatisfied with their robotic surgery experience. 62.5% report they do not intend to integrate robotic surgery into their future practice. 93.8% of residents have a standardized robotic curriculum. 47.5% report using the simulator only during required didactic time with 52.5% having the robotic simulator conveniently located. The majority of residents report that the presence of dual consoles and first-assists in robotic cases enhance their robotic training (93% - 62%, respectively). 72.5% felt like they had more autonomy during laparoscopic cases and 96.8% of residents felt that an attendings' lack of experience impacted their time operating at the surgeon console. General surgery residents report lack of effective OR teaching, real clinical experience, and simulated experience as main barriers in their robotic surgery training. Dual consoles and first-assistants are favorably looked upon. Lack of attending experience and comfort were universally negatively associated with resident participation. For residents interested in robotic surgery, advocating for more robust investment in dual consoles, first-assistants, and faculty development would likely improve their robotic surgery training experience. However, residency programs should consider whether robotic surgery should be a core competency of an already time restricted training paradigm.

The Association Between Force-Velocity Relationship in Countermovement Jump and Sprint With Approach Jump, Linear Acceleration and Change of Direction Ability in Volleyball Players.

The force-velocity (FV) relationship allows the identification of the mechanical capabilities of musculoskeletal system to produce force, power and velocity. The aim of this study was to assess the associations of the mechanical variables derived from the FV relationship with approach jump, linear sprint and change of direction (CoD) ability in young male volleyball players. Thirty-seven participants performed countermovement jumps with incremental loads from bodyweight to 50–100 kg (depending on the individual capabilities), 25-m sprint with split times being recorded for the purpose of FV relationship calculation, two CoD tests (505 test and modified T-test) and approach jump. Results in this study show that approach jump performance seems to be influenced by maximal power output (r = 0.53) and horizontal force production (r = 0.51) in sprinting, as well as force capacity in jumping (r = 0.45). Only the FV variables obtained from sprinting alone contributed to explaining linear sprinting and CoD ability (r = 0.35–0.93). An interesting finding is that sprinting FV variables have similar and some even stronger correlation with approach jump performance than jumping FV variables, which needs to be considered for volleyball training optimization. Based on the results of this study it seems that parameters that refer to horizontal movement capacity are important for volleyball athletic performance. Further interventional studies are needed to check how to implement specific FV-profile-based training programs to improve specific mechanical capabilities that determine volleyball athletic performance and influence the specific physical performance of volleyball players.

Effective light trapping in c-Si thin-film solar cells with a dual-layer split grating.

We propose a dual-layer split nanograting structure in crystalline silicon thin-film solar cells (TFSCs). The split nanograting is designed by introducing two partitioning factors and split times. By employing the finite-difference time-domain method, the light trapping performance and relevant parameters of TFSCs are analyzed and optimized. Numerical computation of optical and electrical simulation shows that the optimal dual-layer split nanograting structure has demonstrated great enhanced light absorption compared with the planar structure. Enhancement of the light trapping effect is associated with light coupling to waveguide modes. The short-circuit current density is reached at 21.66mA/cm2 with an improvement of 54.6% over the planar structure. All results provide a parting thought for the design of TFSC grating structures.

Characterization of strong NV− gradient in the e-beam irradiated diamond sample

We report on studies of a diamond sample with a strong gradient of NV− concentration (between 4 and 36 ppm over 1.5 mm) created by inhomogeneous irradiation with an electron beam. The sample was characterized by spatially resolved luminescence and ODMR spectra and spatial distributions of NV− concentration, strain splitting, and relaxation times T1, T2. Such inhomogeneous sample may find applications in designing optimum conditions for numerous applications in spectroscopy and sensorics.

Crustal structure and deformation in southeastern China revealed by receiver functions

• A V-shaped zone with high Vp/Vs ratio and thin crust observed by receiver functions. • Most stations located near the V-shaped zone exhibit significant crustal anisotropy. • Hot fingers grow from the mantle corner flow and result in Moho uplift in SE China. • Mantle corner flow might be a main reason for crustal thinning in the V-shaped zone. The subduction of the Paleo-Pacific and Philippine plates generates large-scale magmatism and crustal thinning in southeastern (SE) China. However, the dynamic process for crustal thinning in this region is still not well understood. In this study, a large number of receiver function data were used to investigate the crustal thickness and Vp/Vs ratio beneath SE China by the H-κ stacking technique. We also apply a comprehensive analysis method on the Moho Ps converted wave in radial and transverse receiver functions to calculate crustal seismic anisotropy with fast polarization direction and splitting time. The measured results show that the high Vp/Vs ratio (∼1.85) was mainly spread around two areas, forming a “V-shaped” zone. The western branch of the “V-shaped” zone was NS-oriented with a thin crustal thickness of ∼29.1 km beneath the Nanxiang-Jianghan basin. The eastern branch extended along the Tanlu fault with a thin crustal thickness of ∼28.8 km. Moreover, the measured crustal seismic anisotropy also shows that most stations located near the “V-shaped” zone exhibit significant crustal anisotropy with splitting times of 0.20–0.72 s. The fast directions of these stations are parallel to the direction of the V-shaped extension. Combining the geological data, we propose that the “hot fingers” may grow from mantle corner flow in the southern part of the V-shaped zone associated with the collision of the Pacific and Philippine plates. We deduce that the V-shaped crustal thinning and Moho uplift in SE China might be attributed to this mantle corner flow.

Simultaneous Transmission and Reflection Reconfigurable Intelligent Surface Assisted Secrecy MISO Networks

This work exploits the potential of a novel simultaneous transmission and reflection reconfigurable intelligent surface (STAR-RIS) in improving the security in a multiple-input single-output (MISO) network, where three transmission protocols, namely, energy splitting (ES), mode selection (MS), and time splitting (TS), are studied. The objective is to maximize the weighted sum secrecy rate (WSSR) by jointly designing the beamforming (BF) and the transmitting and reflecting coefficients (TARCs). A path-following based technique is first developed to covert the non-convex problem and design the BF and the TARCs in an alternating manner. Then, for the ES scheme, the TARCs are solved by a penalty concave convex procedure (PCCP) method. Besides, the proposed method is extended to the MS by solving a mixed-integer problem. While for the TS scheme, a two-layer optimization method is proposed. Finally, the simulation results validate the superiority of STAR-RIS.

Dynamical Splitting of Spot-producing Magnetic Rings in a Nonlinear Shallow-water Model

Abstract We explore the fundamental physics of narrow toroidal rings during their nonlinear magnetohydrodynamic evolution at tachocline depths. Using a shallow-water model, we simulate the nonlinear evolution of spot-producing toroidal rings of 6° latitudinal width and a peak field of 15 kG. We find that the rings split; the split time depends on the latitude of each ring. Ring splitting occurs fastest, within a few weeks, at latitudes 20°–25°. Rossby waves work as perturbations to drive the instability of spot-producing toroidal rings; the ring split is caused by the “mixed stress” or cross-correlations of perturbation velocities and magnetic fields, which carry magnetic energy and flux from the ring peak to its shoulders, leading to the ring split. The two split rings migrate away from each other, the high-latitude counterpart slipping poleward faster due to migrating mixed stress and magnetic curvature stress. Broader toroidal bands do not split. Much stronger rings, despite being narrow, do not split due to rigidity from stronger magnetic fields within the ring. Magnetogram analysis indicates the emergence of active regions sometimes at the same longitudes but separated in latitude by 20° or more, which could be evidence of active regions emerging from split rings, which consistently contribute to observed high-latitude excursions of butterfly wings during the ascending, peak, and descending phases of a solar cycle. Observational studies in the future can determine how often new spots are found at higher latitudes than their lower-latitude counterparts and how the combinations influence solar eruptions and space weather events.