Strain controllable band alignment and the interfacial and optical properties of tellurene/GaAs van der Waals heterostructures.

By using first principles calculations, we theoretically investigate the electronic structures and the interfacial and optical properties of the two-dimensional tellurene (Te)-gallium arsenide (GaAs) van der Waals heterostructures (vdWHs), i.e., α-Te/GaAs and γ-Te/GaAs, formed using Te and GaAs monolayers. It has been demonstrated that, the semiconductor-semiconductor contacted α-Te/GaAs vdWH exhibits a type-II band alignment with a direct band gap of 0.28 eV while the metal-semiconductor contacted γ-Te/GaAs vdWH has a p-type Schottky contact with a Schottky barrier height (SBH) of 0.36 eV at the interface. The transition from type-II to type-III band alignment is observed firstly in the α-Te/GaAs vdWH when the in-plane biaxial strain is less than -5.2% and larger than 4.4%, meanwhile, the p-type Schottky contact to Ohmic contact transition may be realized in the γ-Te/GaAs vdWH when the in-plane biaxial strain is less than -2.4%. Finally, the maximum optical absorption coefficients of the α- and γ-Te/GaAs vdWHs have been found to be up to 31% and 29%, respectively, and may be modulated effectively by applying in-plane biaxial strain. The obtained results may be of importance in the design of nanoelectronic devices based on the proposed tellurene/GaAs vdWHs.

The Effects of Physical Activity Interventions on Children's Perception: A Systematic Review and Meta-Analysis.

Perception is an essential component of children's psychological development, which is foundational to children's ability to understand and adapt to their external environment. Perception is also a crucial tool for understand and navigating one's surroundings, enabling children to identify objects and react appropriately to settings or situations. Substantial evidence indicates that engaging in physical activity is beneficial for the development of children's perceptual abilities, as the two are closely intertwined. Still, more research is necessary to gain a full understanding of the impact of physical activity on children's perception. To further identify and quantify the effects of physical activity on a number of specific perceptions in children. Systematic review and meta-analysis. Searches were performed using five online databases (i.e., PubMed, SPORTDiscus, PsycINFO, Web of Science, and Cochrane Library) for articles published up to and including June 2023 to identify eligible citations. A total of 12 randomized controlled trials, encompassing 1,761 children under the age of 12, were analyzed. Overall, physical activity as an intervention showed a notable effect on the development of children's perceptions. The meta-analysis indicated that participating in physical activity for 30 minutes around, daily, had a greater impact on children's visual perception and executive functioning than on their motor perception, body perception, and global self-worth (SMD = 1.33, 95% CI: 0.75, 1.91, p < 0.001). The effects of physical activity on children's perception performance varied by participant characteristics, with physical activity having better effects on body perception and overall self-worth in children who were obese or overweight. Furthermore, physical activity can also enhance executive function and attention in children with developmental coordination disorders. The effects of physical activity on children's perception performance varied according to the intervention time, with different activity durations resulting in different perception performances. Therefore, parents and educators must prioritize an appropriate length of physical activity time for children to ensure their optimal growth and development. Registration and protocol CRD42023441119.

Simplified independent triple-sideband signal generation and transmission scheme based on one I/Q modulator at 0.3-THz.

To meet the ultra-bandwidth high-capacity communication, improve spectral efficiency and reduce the complexity of system structure, we have proposed the independent triple-sideband signal transmission system based on photonics-aided terahertz-wave (THz-wave). In this paper, we demonstrate up to 16-Gbaud independent triple-sideband 16-ary quadrature amplitude modulation (16QAM) signal transmission over 20 km standard single mode fiber (SSMF) at 0.3 THz. At the transmitter, independent triple-sideband 16QAM signals are modulated by an in-phase/quadrature (I/Q) modulator. Carrying independent triple-sideband signals optical carrier coupled with another laser to generate independent triple-sideband terahertz optical signals with a carrier frequency interval of 0.3THz. While at the receiver side, enabled by a photodetector (PD) conversion, we successfully obtain independent triple-sideband terahertz signals with a frequency of 0.3THz. Then we employ a local oscillator (LO) to drive mixer to generate intermediate frequency (IF) signal, and only one ADC is used to sample independent triple-sideband signals, digital signal processing (DSP) is finally performed to obtain independent triple-sideband signals. In this scheme, independent triple-sideband 16QAM signals is delivered over 20 km SSMF under the bit error ratio (BER) of 7% hard-decision forward-error-correction (HD-FEC) threshold of 3.8 × 10-3. Our simulation results show that the independent triple-sideband signal can further improve THz system transmission capacity and spectral efficiency. Our simplified independent triple-sideband THz system has a simple structure, high spectral efficiency, and reduced bandwidth requirements for DAC and ADC, which is a promising solution for future high-speed optical communications.

Experimental demonstration of 16QAM/QPSK OFDM-NOMA VLC with LDPC codes and analog pre-equalization.

Non-orthogonal multiple access (NOMA) via power domain multiplexing is widely deployed in bandwidth-limited light-emitting-diode-based visible-light-communication (VLC) systems due to its excellent spectral efficiency. However, quadrature phase-shift keying (QPSK) or even lower-order modulation formats are dominant; therefore, the spectral efficiency can be further improved with the higher-order quadrature amplitude modulation (QAM) modulation. Besides, error propagation (EP) deteriorates the system performance of lower power users during demodulation with imperfect successive interference cancellation. In this paper, we experimentally demonstrate a low-density parity-check (LDPC) codes-enabled 16QAM/QPSK modulation scheme for the orthogonal frequency-division multiplexing-based NOMA-VLC transmission system. Moreover, the analog pre-equalization technique is employed to enhance the modulation bandwidth. The experimental results exhibit that the EP can be significantly mitigated, and the bit error rate performance of lower power users can be improved by up to about 2 orders of magnitude by using LDPC codes and an analog pre-equalization technique.

Hardware-efficient implementation and experimental demonstration of Hermitian-symmetric IFFT for optical DMT transmitter.

Optical discrete multi-tone (DMT) is one type of direct-detection optical orthogonal frequency-division multiplexing (DDO-OFDM), and it is more suitable for cost-sensitive access networks and optical interconnections due to its simple structure. In DMT transmitter, inverse fast Fourier transform (IFFT) is an essential function for achieving OFDM modulation, and its input data are constrained to have Hermitian symmetry (HS). To support high-speed DMT signal generation, a fully-parallel implementation of IFFT is preferable. However, the hardware implementation of the conventional complex-valued IFFT (CC-IFFT) requires large area and has high power consumption. Based on the nature of HS, we design and implement a fully-parallel pipelined 128-point radix-2 decimation-in-time Hermitian-symmetric IFFT (HS-IFFT) by using a single field programmable gate array (FPGA) chip. On-chip resource utilization is analyzed for both the proposed HS-IFFT and CC-IFFT. It exhibits that the HS-IFFT can save up to 35% multipliers, 49% registers and 43% look-up tables (LUTs) compared to the CC-IFFT. Also, by using the HS-IFFT and CC-IFFT, two FPGA-based real-time baseband DMT transmitters are implemented and power consumption is estimated. More than 32% of on-chip power is saved by using the HS-IFFT. Moreover, the two DMT transmitters are also experimentally demonstrated in a short-reach directly-modulated laser (DML)-based optical DMT system. The experimental results show that the HS-IFFT-DMT has the same bit error rate (BER) and error vector magnitude (EVM) performances as the CC-IFFT-DMT in both electrical/optical back-to-back cases (EB2B/OB2B) and post 20-km single-mode fiber (SMF) transmission.

Differences and relationships between talent detection, identification, development and selection in sport: A systematic review.

Although there are numerous studies on talent, especially talent identification, development, and selection, both on influencing factors and model construction or talent prediction, they have relatively independently explored some of its stages. Undeniably, talent development is continuous and phased, with specific tasks to be completed at each step, and these steps have certain differences and relationships. The aim of this review is to provide a clear distinction between the entire talent cultivation process, with the purpose of having better methods and measures for each stage to minimize the turnover rate and ensure the integrity of the talent development process. Through searching the Web of Science ™ database, this review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Selected were original articles in English containing data or models related to talent detection/identification/development/selection in sports. A total of 16 articles were included in the study by reviewing the literature. This overview presents the differences and relationships between the four stages of talent cultivation, where these different aspects are aim, purpose, approach, and emphasis. The relationship is characterized by continuity, progressive, complementary, and mutually. This finding shows that each stage is not developed independently, but is an integral part of the talent training process. Additionally, better differentiation and strengthening of the links between the various talent cultivation stages are considered to contribute to elite athlete development. This review highlights the differences and relationships that exist at each stage of talent cultivation. Meanwhile, some measures are also proposed to strengthen the connection of these phases and how to reduce the turnover rate of talent, which can provide theoretical references for coaches or stakeholders. Based on the results of the review, it is also recommended that future research on talent cultivation could take into account the intrinsic linkages between the various stages and develop talent training programs in a multidimensional way.

Exploring the Multidisciplinary Factors Affecting Sports Talent Identification.

Talent is one of the most significant factors to promote the development of sports undertakings. The present study aimed to explore the factors affecting the identification of sports talents in China's physical education curriculum. Based on the literature review, this study puts forward a model to examine the influencing factors of sports talent identification in China's physical education curriculum using structural equation modeling and uses the structural equation modeling and factor analysis method to verify the hypothesis combined with the results of 310 effective questionnaires. The article summarizes influencing factors from four aspects, namely, physical, psychological, coach, and environmental factors. On the basis of relevant literature, the hypothesis model was established by structural equation modeling. The results show that the main factors affecting the identification of sports talents in the physical education curriculum are personal physical quality performance, psychological quality, coach's knowledge, and the identification policies of schools to sports talents. The conclusion of this study can provide guidance for the reform of the physical education curriculum, the growth of sports talents, and the development of sports talents in China.