Variability of Technical Action Coordination Structure in Boxing at Fatigue

One of the directions of research into movement variability studies it at changing external or internal conditions during motor task performance. The results of such investigations are ambivalent even when analysing movements with similar kinematic structure. The aim of the research was to study the variability of skeletal muscle bioelectric activity and space-time characteristics of various punches in boxing at fatigue. Six highly skilled boxers of different weight classes were involved. We analysed parameters of variation of muscle electromyographic activity, distance and speed of the anthropometric points of body segments, as well as joint movement amplitude under regular conditions and after an aerobic motor load. We found low amplitude variability in most of the skeletal muscles under study, both in regular conditions and after a motor load. At fatigue, amplitude variability of almost all muscles decreased. Under regular conditions, the movement amplitude of the shoulder, elbow and hip joints on the bodyʼs right side was more varied than that in the joints on the left. After a motor load, changes in the variability of joint movement amplitude during the performance of different punches were dissimilar. The most variable were changes in the angles of the right side of the body, especially the elbow and hip joints, when performing a direct punch. The least changes under the load were observed in the movement amplitude of the elbow and hip joints on the left side. Thus, variability changes in kinematic parameters caused by skeletal muscle activity are a mechanism for maintaining stability of motor task performance. Presumably, the central neural control of complex coordination movements in boxers when performing punches is carried out through the formation of kinematic and muscle synergies. More research is needed to clarify the mechanism of formation and functioning of kinematic synergies and their variability.

Conformities distribution contents diamond in kimberlites pipes Yakutian province

The relevance of the work is due to the importance industrial meaning deposits kimberlites type in the production jewelers and technical diamonds. Purpose of the work: study conformities of distribution concentrations diamonds in kimberlites pipes. Factual material: representative data on the sampling prospecting bores and mining excavations with determination contents diamonds in the samples kimberlites and their chemical composition (1911 analyses). Results research. Middle Paleozoic kimberlites pipes Yakutian province on the level contents diamonds subdivide on the three groups: highly productive (pipes Botuobinskaya, Nurbinskaya, Aikhal, Internatsionalnaya, Mir), middle productive (pipes Udachnaya-west, Udachnaya-east, Sytykanskaya, Jybileinaya) and low productive (pipe Komsomolskaya). For highly productive pipes characteristically predominance in percentage samples with very high and high contents diamonds, for middle productive pipes – prevalence samples with middle and low concentrations diamonds, for low productive Komsomolskaya pipe-predominace samples with low contents diamonds. In the kimberlites pipes grow amplitude variability from even to extremely uneven distribution concentrations diamonds on measure diminution their productivity. In the majority study kimberlites pipes with different on upper, middle and low horizons in the intervals of depth from 0 to 1260 metres settled conforming lowering middle concentrations diamonds on the more deep horizons deposits. Show in kimberlites pipes hydrothermal-metasomatic processes carbonatization and quartz influenced on distribution contents diamonds in their. In higly and middle productive pipes province as a result of development these processes marked conforming diminution middle concentrations diamonds in carbonatizated and quartz kimberlites in comparison with their contents in faintly altered kimberlites.

Subtle Oculomotor Difficulties and Their Relation to Motor Skill in Children with Autism Spectrum Disorder

Objectives Sensorimotor difficulties are often reported in autism spectrum disorders (ASD). Visual and motor skills are linked in that the processing of visual information can help in guiding motor movements. The present study investigated oculomotor skill and its relation to general motor skill in ASD by providing a comprehensive assessment of oculomotor control. Methods Fifty children (25 ASD; 25 typically developing [TD]), aged 7–10 years, completed a motor assessment (comprising fine and gross motor tasks) and oculomotor battery (comprising fixation, smooth pursuit, prosaccade and antisaccade tasks). Results No group differences were found for antisaccade errors, nor saccade latencies in prosaccade and antisaccade tasks, but increased saccade amplitude variability was observed in children with ASD, suggesting a reduced consistency in saccade accuracy. Children with ASD also demonstrated poorer fixation stability than their peers and spent less time in pursuit of a moving target. Motor skill was not correlated with saccade amplitude variability. However, regression analyses revealed that motor skill (and not diagnosis) accounted for variance in fixation performance and fast smooth pursuit. Conclusions The findings highlight the importance of considering oculomotor paradigms to inform the functional impact of neuropathologies in ASD and also assessing the presentation of co-occurring difficulties to further our understanding of ASD. Avenues for future research are suggested.

TESS photometry of helium-rich hot subdwarfs: r modes in BD+37°442 and BD+37°1977

ABSTRACT Transiting Exoplanet Survey Satellite photometry of the extremely helium-rich hot subdwarfs BD+37°442 and BD+37°1977 demonstrates multiperiodic low-amplitude variability with principal periods of 0.56 and 1.14 d, respectively, and with both first and second harmonics present. The light curves are not perfectly regular, implying additional periodic and/or non-periodic content. Possible causes are examined, including the binary hypothesis originally introduced to explain X-ray observations, differentially rotating surface inhomogeneities, and pulsations. If the principal photometric periods correspond to the rotation periods, the stars are rotating at approximately 0.7 and 0.3 × break-up, respectively. Surface Rossby waves (r modes) therefore provide the most likely solution.

Revisiting the pulsational characteristics of the exoplanet host star β Pictoris

Context. Exoplanet properties crucially depend on the parameters of their host stars: more accurate stellar parameters yield more accurate exoplanet characteristics. When the exoplanet host star shows pulsations, asteroseismology can be used for an improved description of the stellar parameters. Aims. We aim to revisit the pulsational properties of β Pic and identify its pulsation modes from normalized amplitudes in five different passbands. We also investigate the potential presence of a magnetic field. Methods. We conducted a frequency analysis using three seasons of BRITE-Constellation observations in the two BRITE filters, the about 620-day-long bRing light curve, and the nearly 8-year-long SMEI photometric time series. We calculated normalized amplitudes using all passbands and including previously published values obtained from ASTEP observations. We investigated the magnetic properties of β Pic using spectropolarimetric observations conducted with the HARPSpol instrument. Using 2D rotating models, we fit the normalized amplitudes and frequencies through Monte Carlo Markov chains. Results. We identify 15 pulsation frequencies in the range from 34 to 55 d−1, where two, F13 at 53.6917 d−1 and F11 at 50.4921 d−1, display clear amplitude variability. We use the normalized amplitudes in up to five passbands to identify the modes as three ℓ = 1, six ℓ = 2, and six ℓ = 3 modes. β Pic is shown to be non-magnetic with an upper limit of the possible undetected dipolar field of 300 Gauss. Conclusions. Multiple fits to the frequencies and normalized amplitudes are obtained, including one with a near equator-on inclination for β Pic, which corresponds to our expectations based on the orbital inclination of β Pic b and the orientation of the circumstellar disk. This solution leads to a rotation rate of 27% of the Keplerian breakup velocity, a radius of 1.497 ± 0.025 R⊙, and a mass of 1.797 ± 0.035 M⊙. The ∼2% errors in radius and mass do not account for uncertainties in the models and a potentially erroneous mode-identification.