Feasibility of breaking up sitting time in mainstream and special schools with a cognitively challenging motor task

Background: Children spend 70% of the school day sitting in class. Classroom-based active breaks can benefit children's physical health, but if the breaks are cognitively demanding(i.e., combine physical exertion and mental engagement), they may also improve focus and cognitive functions. Teachers and students play a crucial role in the successful implementation of active breaks, and their perspectives are critical to the feasibility of these strategies. The aim of this study was to assess the feasibility of implementing a cognitively challenging motor task as an active break in mainstream and special primary schools.Methods: A total of 5 teachers in 2 mainstream schools and 7 teachers in 1 special school(attended by children with neurodevelopmental disorders) attended a 20-min training on how to implement a 4-min cognitively challenging active break, before conducting a feasibility trial(twice a day for 1 week). To understand individual perceptions, one-on-one semistructured interviews were conducted before and after the trial with teachers, and focus group interviews were conducted with typically developing children after the trial. Questions were based on a predefined framework for feasibility studies. All interviews were audio recorded, transcribed and analyzed in NVivo 11 using a framework approach. A total of 12 teachers(11 females; 7 between 20 and 34 years old) and 34 children(16 girls; 9.3 § 1.7 years, mean § SD) participated in the interviews.Results: In mainstream schools, teachers viewed the cognitively challenging motor task as appropriate and potentially beneficial for children's health and focus. Children reported enjoying the active breaks. Teachers in special schools viewed the task as complex and potentially frustrating for children. In both school types, children's disruptive behavior and lack of time were seen as the main potential barriers to implementation. The use of music, videos, visual cards, and support staff were noted as potential facilitators.Conclusion: The cognitively challenging motor task was a feasible way to interrupt children's sitting time and promote physical activity in mainstream schools, but required changes in special schools. Further research could investigate the effectiveness of these types of task interruptions on children's physical and cognitive health.

Dynamic Response Behaviors of Upright Breakwaters Under Breaking Wave Impact

The dynamic response behaviors of upright breakwaters under broken wave impact are analysed based on the mass-damper-spring dynamic system model. The effects of the mass, damping, stiffness, natural period, and impulse duration (or oscillation period) on the translation, rotation, sliding force, overturning moment, and corresponding dynamic amplifying factors are studied. It is concluded that the ampli-ying factors only depend on the ratio of the system natural period to impulse duration (or oscillation period) under a certain damping ratio. Moreover, the equivalent static approach to breakwater design is also discussed.

Breaking seed dormancy in Cupressus atlantica Gaussen,an endemicand threatened coniferous tree in Morocco

Cupressus atlantica Gaussen （Cupressaceae） is an endemic and endangered coniferous tree geographically restricted to the N＇Fis valley in South-Western Morocco. Like many forest species, C. atlantica exhibits dormancy which delays and reduces germination. To improve seed germination, different pre-treatments were conducted on C. atlantica seeds after storage for different periods （one, two and five years） including： scarification with sandy paper; soaking seeds in hot distilled water at 60℃ and 80℃ for 15 min and soaking seeds for 48 h in a gibberellic acid （GA3） at 1,000 and 2,000 mg·L-1. Results showed that scarification with sandy paper increased the germination rate of Atlas cypress by up to 67%, indicating that the species possess essentially an exogenous dormancy （physical dormancy） due to the hard seed coat （hardseededness）. Exogenous application of gibberellic acid （GA3） at 1,000 mg.L-1 was also effective in breaking seed dormancy and germination induction. These two treatments induced faster speed germination expressed by low number of days to first germination （8-10 days） and low values of mean germination times （MGT）. However, germination rate, under any treatment, is greatly dependent on the year of seed collection. Seeds collected in year 2004 gave the highest value, suggesting that even after five years of storage, the germination capacity of C. atlantica seeds could remain high. This observation is very interesting in the ex-situ conservation of such endemic and endangered species where the production of seeds is irregular over the years.

Formation Process of Intermittent Molten Bridge Between Au-Plated Contacts at Super Low Breaking Velocity

This paper presents the molten bridge behaviors of Au-plated material at super low breaking velocity conditions by introducing our new designed test rig. The typical waveforms of the contact voltage and contact force during breaking are investigated under the load of 5- 25 V/0.2-1 A and velocity of 25-150 nm/s. It is shown that the intermittent molten bridge is formed from the competition of multitude contact a-spots for current distribution and the solid- liquid mixing characteristics of a molten bridge. Also, it is proved that the bridge is not composed by the completed melted metal by using FEM thermal simulation and the voltage-temperature relation. The observed surface morphology reveals that the scattered and stacked melted regions are attributed to the intermittent bridge. Finally, the effects of breaking velocity and electrical load on bridge length and duration are also analyzed.

A swirling jet from a nozzle with tangential inlets and its characteristics in breaking-up rocks

In order to apply a swirling jet to a PDC drill bit, the nozzle performance influenced by nozzle inlet geometric parameters and rock breaking tests under submerged conditions were studied. Numerical simulation was used to study the influence of the nozzle structure on the swirling intensity and nozzle discharge coefficient. Simulation results indicate that spreading angle of the swirling jet is greater than that of＂ the non-swirling jet, and the swirling intensity of the jet is strongly influenced by the length of the nozzle body but weakly by the number of tangential inlets. Rock breaking tests were conducted to evaluate the performance of the swirling jet. It is found that the swirling jet shows a lower threshold pressure to break the rock samples and could break rock more efficiently compared with the non-swirling jet.

Numerical Study on Rock Breaking Mechanism of Supercritical CO_(2)Jet Based on Smoothed Particle Hydrodynamics

Supercritical carbon dioxide(Sc-CO_(2))jet rock breaking is a nonlinear impact dynamics problem involving many factors.Considering the complexity of the physical properties of the Sc-CO_(2)jet and the mesh distortion problem in dealing with large deformation problems using the finite element method,the smoothed particle hydrodynamics(SPH)method is used to simulate and analyze the rock breaking process by Sc-CO_(2)jet based on the derivation of the jet velocity-density evolution mathematical model.The results indicate that there exists an optimal rock breaking temperature by Sc-CO_(2).The volume and length of the rock fracture increase with the rising of the jet temperature but falls when the jet temperature exceeds 340 K.With more complicated perforation shapes and larger fracture volumes,the Sc-CO_(2)jet can yield a rock breaking more effectively than water jet,The stress analysis shows that the Sc-CO_(2)rock fracturing process could be reasonably divided into three stages,namely the fracture accumulation stage,the rapid failure stage,and the breaking stabilization stage.The high diffusivity of Sc-CO_(2)is identified as the primary cause of the stress fluctuation and W-shaped fracture morphology.The simulated and calculated results are generally in conformity with the published experimental data.This study provides theoretical guidance for further study on Sc-CO_(2)fracturing mechanism and rock breaking efficiency.

Solvent-Induced Symmetry-Breaking Charge Transfer in an Octupolar Triphenylamine Derivative Resolved with Transient Fluorescence Spectroscopy

The excited-state symmetry-breaking charge transfer (SBCT) dynamics in quadrupolar or octupolar molecules without clear infrared markers is usually hard to be tracked directly. In this work, on the basis of the evolution of instantaneous emission dipole moment obtained by femtosecond transient fluorescence spectroscopy, we presented a real-time characterization of the solvent-induced SBCT dynamics in an octupolar triphenylamine derivative. While the emission dipole moment of the octupolar trimer in weakly polar toluene changes little during the excited-state relaxation, it exhibits a fast reduction in a few picoseconds in strongly polar tetrahydrofuran. In comparison with the uorescence dynamics of dipolar monomer, we deduced that the emitting state of the octupolar trimer in strongly polar solvent, which undergoes solvent-induced structural uctuation, changes from exciton-coupled octupolar to excitation localized dipolar symmetry. In weakly polar solvent, the octupolar symmetry of the trimer is largely preserved during the solvation stabilization.

Intermittency of Wind Wave Group Breaking

Knowledge on intermittency of wave breaking is so far limited to a few summary statistics, while the probability distribution of time interval between breaking events can provide a full view of intermittency. Based on a series of experiments on wind wave breaking, such probability distributions are investigated. Breaking waves within a wave group were taken as a single breaking event according to recent studies. Interval between successive wave groups with breaker is the focus of this paper. For intervals in our experiments with different fetch and wind conditions, their distributions are all skewed and weighted on small intervals. Results of Kolmogorov-Smirnov tests on time series of these intervals indicate that they all follow gamma distribution, and some are even exponential type. Average breaking-group-interval decreases with friction velocity and significant steepness until the wind is strong enough;most of them are more than 10 times the dominant wave period. Group breaking probability proposed by Babanin recently and the average number of breaking waves in wave groups are also discussed, and they are seemingly more reasonable and sensitive than traditional breaking probability defined in terms of single wave.

Investigation of hydroxyl-terminated polybutadiene propellant breaking characteristics and mechanism impacted by submerged cavitation water jet

A submerged cavitation water jet(SCWJ)is an effective method to recycle solid propellant from obsolete solid engines by the breaking method.Solid propellant's breaking modes and mechanical process under SCWJ impact are unclear.This study aims to understand those impact breaking mechanisms.The hydroxyl-terminated polybutadiene(HTPB)propellant was chosen as the research material,and a self-designed test system was used to conduct impact tests at four different working pressures.The high-speed camera characterized crack propagation,and the DIC method calculated strain change during the impact process.Besides,micro and macro fracture morphologies were characterized by scanning electron microscope(SEM)and computed tomography(CT)scanning.The results reveal that the compressive strain concentration region locates right below the nozzle,and the shear strain region distributes symmetrically with the jet axis,which increases to 4% at first 16th ms,the compressive strain rises to 2% and 6% in the axial and transverse direction,respectively.The two tensile cracks formed first at the compression strain concentrate region,and there generate many shear cracks around the tensile cracks,and those shear cracks that develop and aggregate cause the cracks to become wider and cut through the tensile cracks,forming the tensile-shear cracks and the impact parts eventually fail.The HTPB propellant forms a breaking hole shaped conical after impact 10 s.The mass loss increases by 17 times at maximum,with the working pressure increasing by three times.Meanwhile,the damage value of the breaking hole remaining on the surface increases by 7.8 times while 2.9 times in the depth of the breaking hole.The breaking efficiency is closely affected by working pressures.The failure modes of HTPB impacted by SCWJ are classified as tensile crack-dominated and tensile-shear crack-dominated damage mechanisms.

Study on the Set-up and Set-down Induced by Breaking Waves Over A Reef

This paper proposes an equation to calculate breaking wave induced wave set-up and set-down along reef flat. The mathematical equation was derived based on the theory of radiation stress and the conservation of wave energy. The equation is primarily determined by several physical variables including the breaking wave index, the stable wave index, the attenuation coefficient of wave energy flux, and the flow velocity in the re-stabilization zone. A series of laboratory experiments were carried out to calibrate the theoretical equations. Specifically, the breaking wave index,the stable wave index, and the velocity over the reef flat were measured in the laboratory. The attenuation coefficient of wave energy flux in our theoretical equation was determined by calibration by comparing with the laboratory measured wave height. Furthermore, it has been put forward that the velocity based on cnoidal wave theory could be used to determine the velocity over the reef flat if there is no velocity measurement available. Overall, the proposed equation can provide satisfactory prediction of wave set-up and set-down along the reef flat.

Symmetry breaking in the opinion dynamics of a multi-group project organization

A bounded confidence model of opinion dynamics in multi-group projects is presented in which each group＇s opinion evolution is driven by two types of forces：（i） the group＇s cohesive force which tends to restore the opinion back towards the initial status because of its company culture;and（ii） nonlinear coupling forces with other groups which attempt to bring opinions closer due to collaboration willingness.Bifurcation analysis for the case of a two-group project shows a cusp catastrophe phenomenon and three distinctive evolutionary regimes,i.e.,a deadlock regime,a convergence regime,and a bifurcation regime in opinion dynamics.The critical value of initial discord between the two groups is derived to discriminate which regime the opinion evolution belongs to.In the case of a three-group project with a symmetric social network,both bifurcation analysis and simulation results demonstrate that if each pair has a high initial discord,instead of symmetrically converging to consensus with the increase of coupling scale as expected by Gabbay＇s result（Physica A 378（2007） p.125 Fig.5）,project organization（PO） may be split into two distinct clusters because of the symmetry breaking phenomenon caused by pitchfork bifurcations,which urges that apart from divergence in participants＇ interests,nonlinear interaction can also make conflict inevitable in the PO.The effects of two asymmetric level parameters are tested in order to explore the ways of inducing dominant opinion in the whole PO.It is found that the strong influence imposed by a leader group with firm faith on the flexible and open minded follower groups can promote the formation of a positive dominant opinion in the PO.

VIBRATING-UPLIFT ROCKING MOTION OF CAISSONBREAKWATERS UNDER VARIOUS BREAKINGWAVE IMPACT FORCES

Overturning is one of principal failure types of caisson breakwaters and is an essential content of stability examination in caisson breakwater design. The mass-spring-dashpot model of caisson-foundation system is used to simulate the vibrating-uplift rocking motion of caisson under various types of breaking wave impact forces, i.e., single peak impact force, double peak impact force, and shock-damping oscillation impact force. The effects of various breaking wave types and the uplift rocking motion on dynamic response behaviors of caisson breakwaters are investigated. It is shown that the dynamic responses of a caisson are significantly different under different types of breaking wave impact forces even when the amplitudes of impact forces are equal. Though the rotation of a caisson is larger due to the uplift rocking motion, the displacement, the sliding force and the overturning moment of the caisson are significantly reduced. It provides the theoretical base for the design idea that the uplift rocking motion of caisson is allowed in design.

Time-Reversal Symmetry Breaking: an Evidence for Spin Pairing in High-T_(c) Superconductors

Effective spin coupling leads to local triplet pairing in the antiferromagnetically ordered CuO2 plane as shown by the K-J model[Guo et al.Chin.Phys.Lett.18(2001)103].The precession of the spin triplet(S=1,Sz=0)in the CuO2 plane does not hold time-reversal invariance due to the dimpled CuO structure,which not only modifies the gap function but also contributes to the asymmetry of the high-Tc tunneling conductance.In principle,the effect of time-reversal symmetry breaking can be manifested by the variation of the conductance asymmetry by applying a magnetic field at superconductor-insulator-normal metal junction,which should provide a direct evidence for triplet pairing in the high-Tc superconductors.

Superconducting Properties and Absence of Time Reversal Symmetry Breaking in the Noncentrosymmetric Superconducting Compounds Ta_(x)Re_(1-x)(0.1≤x≤0.25)

Unconventional superconductivity,in particular,in noncentrosymmetric systems,has been a long-sought topic in condensed matter physics.Recently,Re-based superconductors have attracted great attention owing to the potential time-reversal symmetry breaking in their superconducting states.We report the superconducting properties of noncentrosymmetric compounds Ta_(x)Re_(1-x) with 0.1 ≤x≤0.25,and find that the superconducting transition temperature reaches a maximum of ~8 K at the optimal level x=0.15.Nevertheless,muon-spin rotation and relaxation measurements reveal no time-reversal symmetry breaking existing in its superconducting state,which is in sharp contrast to both centrosymmetric Re metal and many other noncentrosymmetric Re-based superconductors.

Spontaneous U(1) Symmetry Breaking in Coupled Bose System

Adding a U（1） symmetry breaking term √V（λ1a0 ＋ λ1＊a0） ＋ √V（λ2b0 ＋ λ2＊b0） to Bogoliubov＇s truncated Hamiltonian HB for a weakly interacting coupled Bose system, by using the mean-field approximation rather than the c-number approximation, we And that, via a Feshbach resonance at zero temperature, the states of the coupled Bose system are generalized SU（1,1） SU（1,1） coherent states. The Bose-Einstein condensation occurs in response to the spontaneous U（1） symmetry breaking.

Super-large Gas Storage Found in Central Sichuan Longwangmiao Formation:a Record-breaking New Discovery

Before the founding of New China,when exploring the Sichuan Basin,some geologists found a giant paleouplift with a height of about 2000-3000 meters in the long strip irregular region underground starting from Suining(Longnvsi)in the east,connecting Ya'an in the west,reaching Zizhong(Leshan)in the south and Mianyang in the north and named it Leshan-Longnvsi Paleouplift.

Cavitation cloud impingement and scattering motion of jet in rock breaking process

The cavitation cloud impingement of the jet in the rock breaking process was experimentally investigated to reveal the jet erosion mechanism in drilling of petroleum exploitation. Serial erosion tests and flow visualization were performed, where the cavitation cloud motion in the erosion crater was obtained with the designed transparent specimen. Various erosion patterns were identified in the whole erosion process based on the eroded specimen topography. The shallow eroded crater with a shrinking erosion area is generated by the combination of impinging and scattering cavitation clouds. The increase of l_(d) promotes the development of cavitation cloud σ_(c) but reduces the impingement frequency f_(d), suggesting that the jet aggressive ability is enhanced when the balance between σ_(c) and f_(d) is reached. The cavitation cloud motion in the erosion crater was investigated with the transparent specimen. The erosion in the crater at shorter exposure periods T_(e) is generated by the combination of impingement and restricted scattering of cavitation clouds. With the continuous development of the erosion damage, the jet's aggressive ability is diminished due to the erosion expansion on sandstone, where the cavitation clouds impinge on the target and then collapse and vanish without restricted scattering.

Parity-Time symmetry helps breaking a new limit

Parity-Time(PT)symmetry is an emerging concept in quantum mechanics where non-Hermitian Hamiltonians can exhibit real eigenvalues.Now,PT symmetric optical microresonators have been demonstrated to break the bandwidth-efficiency limit for nonlinear optical signal processing.

Two-fold symmetry of the in-plane resistance in kagome superconductor Cs(V_(1-x)Ta_(x))_(3)Sb_(5) with enhanced superconductivity

The kagome superconductor CsV_(3)Sb_(5) has attracted widespread attention due to its rich correlated electron states including superconductivity, charge density wave(CDW), nematicity, and pair density wave. Notably, the modulation of the intertwined electronic orders by the chemical doping is significant to illuminate the cooperation/competition between multiple phases in kagome superconductors. In this study, we have synthesized a series of tantalum-substituted Cs(V_(1-x)Ta_(x))_(3)Sb_(5) by a modified self-flux method. Electrical transport measurements reveal that CDW is suppressed gradually and becomes undetectable as the doping content of x is over 0.07. Concurrently, the superconductivity is enhanced monotonically from T_(c) ~ 2.8 K at x = 0 to 5.2 K at x = 0.12. Intriguingly, in the absence of CDW, Cs(V_(1-x)Ta_(x))_(3)Sb_(5)(x = 0.12) crystals exhibit a pronounced two-fold symmetry of the in-plane angular-dependent magnetoresistance(AMR) in the superconducting state, indicating the anisotropic superconducting properties in the Cs(V_(1-x)Ta_(x))_(3)Sb_(5). Our findings demonstrate that Cs(V_(1-x)Ta_(x))_(3)Sb_(5) with the non-trivial band topology is an excellent platform to explore the superconductivity mechanism and intertwined electronic orders in quantum materials.

Pursuing Excellence in the Biomedical Field:The Inspiring Story of Prof.Dr.Mike Chan——An Interview with Prof.Dr.Mike Chan,Scientist,Author and Founder of European Wellness Biomedical Group

From humble beginnings to global influence,Prof.Dr.Mike K.S.Chan's story is a remarkable tale of passion,perseverance,and groundbreaking innovation in the biomedical field.As the co-owner and founder of the European Wellness Biomedical Group,he has dedicated his life to advancing biotechnology,stem cell research,and regenerative medicine,profoundly impacting lives across the globe.