Interatomic Coulombic electron capture (ICEC) is an environment-mediated process in which a free electron attaches to a species by transferring excess energy to a neighbor. While previous theoretical investigations assumed fixed nuclei, recent studies indicate that nuclear dynamics significantly influences the ICEC process. In this work, we incorporate the vibrational motion into an analytical model of the ICEC cross section, including both energy and electron transfer. To validate this approach, we compare the results to the adiabatic-nuclei approximation based on fixed-nuclei ab initio R-matrix calculations. We apply our theory to the helium-neon dimer, which is ideal for studying diverse dynamical effects. We show that while vibrational dynamics can slightly reduce ICEC efficiency, ICEC remains dominant over photorecombination and can trigger dimer dissociation. Accounting for the nuclear motion also enables to describe the broadening of the electron spectrum and enables evaluation of temperature-dependent cross sections-capabilities beyond the reach of fixed-nuclei approaches.

• Publikační typ
• časopisecké články MeSH

Independent walking is an important milestone in a child's development. The maturation of central nervous system, changes in body proportions, spatiotemporal parameters of gait and their variability change are dependent on age. The first aim of this study was to compare non-normalized and normalized spatiotemporal parameters and their variability in children. The second aim was to determine which spatiotemporal parameters are most affected by aging. Data from 64 typically developing children (age: 2.0-6.9 years), who walked at a self-selected speed along a 10m walkway, were collected with a motion capture system. Spatiotemporal parameters were normalized based on leg length. The main effect of the non-normalized walking speed revealed a moderate effect size (ES = 0.72) comparing 2- and 3-years-old, a large effect size comparing 2- and 6-years-old (ES = 1.77), and a large ES comparing 3- and 6-years-old (ES = 1.22). The normalized stride width parameter showed a statistically significant difference with large effect size between 2 vs 3 (ES = 1.00), 2 vs 6 (ES = 3.17), and 3 vs 6 (ES = 1.96). A statistically significant decrease in intra-individual gait variability with increasing age was observed in all parameters except for stride width. The variability of stride width may serve as a parameter in 2-year-olds to assess deviations from typically developing children. The assessment of effect size could be a useful indicator for clinical practice.

• MeSH
• chůze (způsob) * fyziologie   MeSH
• chůze * fyziologie   MeSH
• dítě MeSH
• lidé MeSH
• předškolní dítě MeSH
• rychlost chůze fyziologie   MeSH
• snímání pohybu MeSH
• stárnutí fyziologie   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• předškolní dítě MeSH
• Publikační typ
• časopisecké články MeSH

Functional connectivity analysis of resting-state fMRI data has recently become one of the most common approaches to characterizing individual brain function. It has been widely suggested that the functional connectivity matrix is a useful approximate representation of the brain's connectivity, potentially providing behaviorally or clinically relevant markers. However, functional connectivity estimates are known to be detrimentally affected by various artifacts, including those due to in-scanner head motion. Moreover, as individual functional connections generally covary only very weakly with head motion estimates, motion influence is difficult to quantify robustly, and prone to be neglected in practice. Although the use of individual estimates of head motion, or group-level correlation of motion and functional connectivity has been suggested, a sufficiently sensitive measure of individual functional connectivity quality has not yet been established. We propose a new intuitive summary index, Typicality of Functional Connectivity, to capture deviations from standard brain functional connectivity patterns. In a resting-state fMRI dataset of 245 healthy subjects, this measure was significantly correlated with individual head motion metrics. The results were further robustly reproduced across atlas granularity, preprocessing options, and other datasets, including 1,081 subjects from the Human Connectome Project. In principle, Typicality of Functional Connectivity should be sensitive also to other types of artifacts, processing errors, and possibly also brain pathology, allowing extensive use in data quality screening and quantification in functional connectivity studies as well as methodological investigations.

• Klíčová slova
• atlas, functional connectivity, motion, quality, rs-fMRI,
• MeSH
• artefakty MeSH
• atlasy jako téma * MeSH
• datové soubory jako téma * MeSH
• dospělí MeSH
• hlava - pohyby MeSH
• konektom * metody   normy   MeSH
• lidé MeSH
• magnetická rezonanční tomografie * metody   normy   MeSH
• mladý dospělý MeSH
• mozek diagnostické zobrazování   fyziologie   MeSH
• počítačové zpracování obrazu * metody   normy   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Translation accuracy is one of the most critical factors for protein synthesis. It is regulated by the ribosome and its dynamic behavior, along with translation factors that direct ribosome rearrangements to make translation a uniform process. Earlier structural studies of the ribosome complex with arrested translation factors laid the foundation for an understanding of ribosome dynamics and the translation process as such. Recent technological advances in time-resolved and ensemble cryo-EM have made it possible to study translation in real time at high resolution. These methods provided a detailed view of translation in bacteria for all three phases: initiation, elongation, and termination. In this review, we focus on translation factors (in some cases GTP activation) and their ability to monitor and respond to ribosome organization to enable efficient and accurate translation. This article is categorized under: Translation > Ribosome Structure/Function Translation > Mechanisms.

• Klíčová slova
• cryoelectron microscopy, structural biology, translation,
• MeSH
• elektronová kryomikroskopie metody   MeSH
• ribozomy * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

PURPOSE: The optimal motion management strategy for patients receiving stereotactic arrhythmia radioablation (STAR) for the treatment of ventricular tachycardia (VT) is not fully known. We developed a framework using a digital phantom to simulate cardiorespiratory motion in combination with different motion management strategies to gain insight into the effect of cardiorespiratory motion on STAR. METHODS AND MATERIALS: The 4-dimensional (4D) extended cardiac-torso (XCAT) phantom was expanded with the 17-segment left ventricular (LV) model, which allowed placement of STAR targets in standardized ventricular regions. Cardiac- and respiratory-binned 4D computed tomography (CT) scans were simulated for free-breathing, reduced free-breathing, respiratory-gating, and breath-hold scenarios. Respiratory motion of the heart was set to population-averaged values of patients with VT: 6, 2, and 1 mm in the superior-inferior, posterior-anterior, and left-right direction, respectively. Cardiac contraction was adjusted by reducing LV ejection fraction to 35%. Target displacement was evaluated for all segments using envelopes encompassing the cardiorespiratory motion. Envelopes incorporating only the diastole plus respiratory motion were created to simulate the scenario where cardiac motion is not fully captured on 4D respiratory CT scans used for radiation therapy planning. RESULTS: The average volume of the 17 segments was 6 cm3 (1-9 cm3). Cardiac contraction-relaxation resulted in maximum segment (centroid) motion of 4, 6, and 3.5 mm in the superior-inferior, posterior-anterior, and left-right direction, respectively. Cardiac contraction-relaxation resulted in a motion envelope increase of 49% (24%-79%) compared with individual segment volumes, whereas envelopes increased by 126% (79%-167%) if respiratory motion also was considered. Envelopes incorporating only the diastole and respiration motion covered on average 68% to 75% of the motion envelope. CONCLUSIONS: The developed LV-segmental XCAT framework showed that free-wall regions display the most cardiorespiratory displacement. Our framework supports the optimization of STAR by evaluating the effect of (cardio)respiratory motion and motion management strategies for patients with VT.

• MeSH
• čtyřrozměrná počítačová tomografie MeSH
• dýchání * MeSH
• fantomy radiodiagnostické MeSH
• lidé MeSH
• pohyb těles MeSH
• srdce * diagnostické zobrazování   účinky záření   MeSH
• srdeční arytmie MeSH
• srdeční komory diagnostické zobrazování   účinky záření   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

The temporomandibular joint (TMJ) is typically involved in 45-87% of children with Juvenile Idiopathic Arthritis (JIA). Accurate diagnosis of JIA is difficult as various clinical tests, including MRI, disagree. The purpose of this study is to optimize the methodological aspects of Dynamic Contrast Enhanced (DCE) MRI of the TMJ in children. In this cross-sectional study, including data from 73 JIA affected children, aged 6-15 years, effects of motion correction, sampling rate and parametric modelling on DCE-MRI data is investigated. Consensus among three radiologists determined the regions of interest. Quantitative perfusion parameters were estimated using four perfusion models; the Adiabatic Approximation to Tissue Homogeneity (AATH), Distributed Capillary Adiabatic Tissue Homogeneity (DCATH), Gamma Capillary Transit Time (GCTT) and Two Compartment Exchange (2CXM) models. Effects of motion correction were evaluated by a sum of least squares between corrected raw data and the GCTT model. The effect of systematically down sampling the raw data was tested. The sum of least squares was computed across all pharmacokinetic models. Relative difference perfusion parameters between the left and right TMJ were used for an unsupervised k-means based stratification of the data based on a principal component analysis, as well as for a supervised random forest classification. Diagnostic sensitivity and specificity were computed relative to structural image scorings. Paired sample t-tests, as well as ANOVA tests, were used (significant threshold: p < 0.05) with Tukeys post hoc test. High-level elastic motion correction provides the best least square fit to the GCTT model (percental improvement: 72-84%). A 4 s sampling rate captures more of the potentially disease relevant signal variations. The various parametric models all leave comparable residues (relative standard deviation: 3.4%). In further evaluation of DCE-MRI as a potential diagnostic tool for JIA a high-level elastic motion correction scheme should be adopted, with a sampling rate of at least 4 s. Results suggest that DCE-MRI data can be a valuable part in JIA diagnostics in the TMJ.

• Klíčová slova
• DCE MRI, JIA, Motion correction, Sampling rate, TMJ,
• MeSH
• artefakty MeSH
• dítě MeSH
• juvenilní artritida diagnostické zobrazování   MeSH
• lidé MeSH
• magnetická rezonanční tomografie * MeSH
• mladiství MeSH
• počítačové zpracování obrazu * MeSH
• pohyb * MeSH
• předškolní dítě MeSH
• průřezové studie MeSH
• senzitivita a specificita MeSH
• statistické modely * MeSH
• temporomandibulární kloub diagnostické zobrazování   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Motion Capture (MoCap) is rapidly growing in the sports, biomechanics, healthcare, and medicine segments, where accuracy is crucial. Current research studies are concurrently confirming that the accuracy can be determined only for the specific analyzed configuration and thus recommending performing your own accuracy verification on your specific setup. However, it is often hard to perform since it requires significant effort, time, knowledge of statistical data analysis and often equipment and tools that are not commonly available. This paper deals with this by creating a standardized setup with carefully evaluated accuracy, substituting the on-site validation process (in case of using such a setup) or providing the worst-case accuracy (when a more advanced setup is used). The setup is designed to be low-cost, easily reproducible and cover a wide range of applications - thus VICON setup with five VERO v1.3 cameras is used. The accuracy was evaluated using the robotic manipulator EPSON C3, determining that the absolute positioning accuracy of such a standardized setup is 0.65 mm on average (SD = 0.48, with maximal error of 2.47 mm) and rotation accuracy 0.40° (SD = 0.35, with maximal error of 2.0°), which is negligible considering the experimental diameter of 1.4 m and full angular span. The major source of error was specific to particular spatial and rotational positions; other systematic and other random errors were noticeably smaller. If the standardized setup is used and all its requirements are met, a similar accuracy as validated above can be expected without the need to explicitly validate the specific configuration, which is time-consuming and resource-intensive.

• Klíčová slova
• Accuracy assessment, Motion capture, Standardization, VICON, Validation,
• Publikační typ
• časopisecké články MeSH

AIMS: The main purpose of this study was to determine the changes in kinematic parameters of ischemic stroke affected upper limbs, during simple functional activity, to determine the most relevant changes. METHODS: The OptiTrack system was used for motion capture. To determine upper extremity function in Activities of Daily Living (ADL) tasks. During particular phases, the following matrices were chosen: mean and peak speed, normalized movement unit, normalized jerk and phase movement time. The chosen matrices represent the speed and smoothness profile of end-point data. The the arm-trunk compensation was also taken into consideration. Twenty stroke patients, in early (G1 from 1 to 3 months after stroke) and chronic stage (G2 from 6 months to 1 year), were studied. The large and small cylinder forward and back transporting phases were evaluated. RESULTS: The most significant differences between groups G1 and G2 were in mean and peak speed of the forward transport of the large and small cylinders for the paretic limb. Significant differences were also found for the smoothness (measured by movement unit, mean and peak speed and jerk) where the G2 group had a rougher motion. There were also differences in arm-trunk compensation in the frontal plane. CONCLUSION: The variables used in the study showed applicability in assessing kinematic parameters in both the early and chronic period after stroke.

• Publikační typ
• časopisecké články MeSH

In taekwondo, there is a lack of consensus about how the kick sequence occurs. The aim of this study was to analyse the peak velocity (resultant and value in each plane) of lower limb segments (thigh, shank and foot), and the time to reach this peak velocity in the kicking lower limb during the execution of the roundhouse kick technique. Ten experienced taekwondo athletes (five males and five females; mean age of 25.3 ±5.1 years; mean experience of 12.9 ±5.3 years) participated voluntarily in this study performing consecutive kicking trials to a target located at their sternum height. Measurements for the kinematic analysis were performed using two 3D force plates and an eight camera motion capture system. The results showed that the proximal segment reached a lower peak velocity (resultant and in each plane) than distal segments (except the peak velocity in the frontal plane where the thigh and shank presented similar values), with the distal segment taking the longest to reach this peak velocity (p < 0.01). Also, at the instant every segment reached the peak velocity, the velocity of the distal segment was higher than the proximal one (p < 0.01). It provides evidence about the sequential movement of the kicking lower limb segments. In conclusion, during the roundhouse kick in taekwondo inter-segment motion seems to be based on a proximo-distal pattern.

• Klíčová slova
• biomechanics, combat sports, execution technique, kinetic link, pattern,
• Publikační typ
• časopisecké články MeSH

Rapidly rotating bodies moving in curved space-time experience the so-called spin-curvature force, which becomes important for the motion of compact objects in gravitational-wave inspirals. As a first approximation, this effect is captured in the motion of a spinning test particle. We solve the equations motion of a spinning particle to leading order in spin in arbitrary static and spherically symmetric space-times in terms of one-dimensional closed-form integrals. This solves the problem and proves its integrability in a wide range of modified gravities and near exotic compact objects. Then, by specializing to the case of bound orbits in Schwarzschild space-time, we demonstrate how to express the solution in the form of Jacobi elliptic functions.

• Publikační typ
• časopisecké články MeSH