Fractal Dimension Research Articles

Dynamic Changes of Air Particle Pollutants and Scale Regulation of Forest Landscape in a Typical High-Latitude City

Particulate pollutants, particularly PM2.5 and PM10, pose serious threats to human health and environmental quality. Therefore, effectively mitigating and reducing the concentrations of these pollutants is crucial for human survival and development. In this study, we analyzed the distribution characteristics of air particulate pollutants in a typical high-latitude city, extracted urban forest areas from high-resolution remote sensing images, and examined the changing characteristics of PM concentration and the relationship between landscape pattern indexes and PM at different scales. The results showed that the concentrations of PM2.5 and PM10 were highest in winter and lowest in summer. At the small scales of 0.5 km × 0.5 km to 1.5 km × 1.5 km, PM concentration decreased with the decrease in PARA (Perimeter–Area Ratio). At the mesoscales of 2 km × 2 km to 2.5 km × 2.5 km, both PARA and CIRCLE (Related Circumscribing Circle) were highly significant (p < 0.001) correlated with PM concentration. At the large scales of 3 km × 3 km to 4 km × 4 km, PARA and PAFRAC (Perimeter–Area Fractal Dimension) were positively correlated with PM concentration. Our study indicates that reducing the complexity of forest patches in small-scale planning can help mitigate particulate air pollution. In the medium scale of urban forest planning, the more regular the forest patch shape and the more similar the patch shape to the strip, the better PM can be alleviated, while in large-scale planning, increasing the forest area and making the patches more normalized and simplified can reduce PM concentration. Moreover, reducing the complexity of forest patches can significantly mitigate PM pollution at all scales. The results of this research provide theoretical support and guidance for improving air quality in urban forest planning at different scales.

Development of Imaging Complexity Biomarkers for Prediction of Symptomatic Radiation Pneumonitis in Patients with Non-Small Cell Lung Cancer, Focusing on Underlying Lung Disease

Objectives: We aimed to develop imaging biomarkers to predict radiation pneumonitis (RP) in non-small cell lung cancer (NSCLC) patients undergoing thoracic radiotherapy. We hypothesized that measuring morphometric complexity in the lung using simulation computed tomography may provide objective imaging biomarkers for lung parenchyma integrity, potentially forecasting the risk of RP. Materials and Methods: A retrospective study was performed on medical records of 175 patients diagnosed with NSCLC who had received thoracic radiotherapy. Three indices were utilized to measure the morphometric complexity of the lung parenchyma: box-counting fractal dimension, lacunarity, and minimum spanning tree (MST) fractal dimension. Patients were dichotomized into two groups at median values. Cox proportional hazard models were constructed to estimate the hazard ratios for grade ≥ 2 or grade ≥ 3 RP. Results and Conclusions: We found significant associations between lung parenchymal morphometric complexity and RP incidence. In univariate Cox-proportional hazard analysis, patients with a lower MST fractal dimension had a significantly higher hazard ratio of 2.296 (95% CI: 1.348–3.910) for grade ≥ 2 RP. When adjusted for age, sex, smoking status, category of the underlying lung disease, category of radiotherapy technique, clinical stage, histology, and DLCO, patients with a lower MST fractal dimension showed a significantly higher hazard ratio of 3.292 (95% CI: 1.722–6.294) for grade ≥ 2 RP and 7.952 (95% CI: 1.722 36.733) for grade ≥ 3 RP than those with a higher MST fractal dimension. Patients with lower lacunarity exhibited a significantly lower hazard ratio of 0.091 (95% CI: 0.015–0.573) for grade ≥ 3 RP in the adjusted model. We speculated that the lung tissue integrity is captured by morphometric complexity measures, particularly by the MST fractal dimension. We suggest the MST fractal dimension as an imaging biomarker for predicting the occurrence of symptomatic RP after thoracic radiotherapy.

How does the direction of region of interest selection affect the fractal dimension?

Introduction Fractal analysis (FA) is a computational method used to quantify the complex trabecular structure of bone. While FA has been widely applied in dentistry, there are challenges in standardizing the technique due to factors such as image resolution, region of interest (ROI) selection, and image processing. This study aimed to investigate the impact of the direction of ROI selection (DROIS) on fractal dimension (FD) calculations. Panoramic radiographs of 226 individuals aged 20-35 years were analyzed. ROIs were selected on the mandibular condyle, angular region, and mental region, and oriented at 0°, 22.5°, 45°, and 67.5° angles. FD was calculated using the box-counting method in ImageJ. The Friedman test and Wilcoxon signed-rank test were used for statistical analysis. The FD values differed significantly between the angled ROI groups in all three regions (Friedman test, p < 0.0001).Pairwise comparisons showed significant differences in FD between most ROI orientations, except between 22.5° and 67.5° in the angular region. DROIS is an important factor that should be considered in FA studies to ensure reliable and reproducible FD values. Appropriate methodological choices can help account for the influence of DROIS on FD calculations..

Mechanical properties and crack deflection mechanisms in 3D-Printed porous geopolymers with cellular structures

ABSTRACT This study focuses on using helical design patterns via 3D printing to create geopolymer with a highly porous structure in order to enhance their strength-density relationship and fracture properties. In this regard, to create porous structure, different pitch angles and infill densities were chosen, and mechanical and fracture properties were examined. The results of mechanical strength tests revealed that while the pitch angle does not significantly affect compressive strength, flexural strength is improved by implementing a low pitch angle helical structure, which leads to the strength-density relationship improvement. Additionally, the work of fracture results demonstrated an enhancement for samples with low pitch angles, such as α15° and α30°, compared to cast and non-directional printed samples. The digital image correlation and fracture surface analysis showed several fracture mechanisms, predominantly crack deflection and twisting, in samples with low pitch angles, which contributes to the observed improvements in the work of fracture.

Evaluating the Impact of Retinal Vessel Segmentation Metrics on Retest Reliability in a Clinical Setting: A Comparative Analysis Using AutoMorph.

Current research on artificial intelligence-based fundus photography biomarkers has demonstrated inconsistent results. Consequently, we aimed to evaluate and predict the test-retest reliability of retinal parameters extracted from fundus photography. Two groups of patients were recruited for the study: an intervisit group (n = 28) to assess retest reliability over a period of 1 to 14days and an intravisit group (n = 44) to evaluate retest reliability within a single session. Using AutoMorph, we generated test and retest vessel segmentation maps; measured segmentation map agreement via accuracy, sensitivity, F1 score and Jaccard index; and calculated 76 metrics from each fundus image. The retest reliability of each metric was analyzed in terms of the Spearman correlation coefficient, intraclass correlation coefficient (ICC), and relative percentage change. A linear model with the input variables contrast-to-noise-ratio and fractal dimension, chosen by a P-value-based backward selection process, was developed to predict the median percentage difference on retest per image based on image-quality metrics. This model was trained on the intravisit dataset and validated using the intervisit dataset. In the intervisit group, retest reliability varied between Spearman correlation coefficients of 0.34 and 0.99, ICC values of 0.31 to 0.99, and mean absolute percentage differences of 0.96% to 223.67%. Similarly, in the intravisit group, the retest reliability ranged from Spearman correlation coefficients of 0.55 and 0.96, ICC values of 0.40 to 0.97, and mean percentage differences of 0.49% to 371.23%. Segmentation map accuracy between test and retest never dropped below 97%; the mean F1 scores were 0.85 for the intravisit dataset and 0.82 for the intervisit dataset. The best retest was achieved with disc-width regarding the Spearman correlation coefficient in both datasets. In terms of the Spearman correlation coefficient, the worst retests of the intervisit and intravisit groups were tortuosity density and artery tortuosity density, respectively. The intravisit group exhibited better retest reliability than the intervisit group (P < 0.001). Our linear model, with the two independent variables contrast-to-noise ratio and fractal dimension predicted the median retest reliability per image on its validation dataset, the intervisit group, with an R2 of 0.53 (P < 0.001). Our findings highlight a considerable volatility in the reliability of some retinal biomarkers. Improving retest could allow disease progression modeling in smaller datasets or an individualized treatment approach. Image quality is moderately predictive of retest reliability, and further work is warranted to understand the reasons behind our observations better and thus ensure consistent retest results.

The effect of single walled carbon nanotubes on conductivity and thermal properties of glass fiber reinforced composites

Abstract This paper reports on a comprehensive study of the effect of single-walled carbon nanotube (SWCNT) on the alternating current (AC) conductivity, thermal and morphological properties of the unsaturated polyester based glass fiber reinforced polymer composite (GFRPC). AC conductivity measurements were carried out using the impedance spectrum and thermal measurements were carried out using differential scanning calorimetry (DSC) at a temperature range of 24-900 °C and heating rates of 20 °C/min. Impedance results showed that the conductivity behavior in the nanotube-loaded composite laminate obeys a Jonscher-type mechanism. At low frequencies, the conductivity value remains almost constant for the doped material and takes the value of 10-5 S/cm. It is observed that the AC conductivity starts to increase after the critical frequency value of approximately 103 Hz and increases up to 10-2 S/cm due to hopping and tunneling mechanisms caused by space charge polarization accumulated in the local regions at high frequencies. The pure material with an insulating nature also exhibited a typical insulating behavior. Thermal testing showed that nanotube reinforcement increases thermal conductivity in three different directions. DSC thermocurves analysis also revealed that the addition of carbon nanotubes increased the glass transition temperature of the material from 180°C to 190°C. The scaling and fractal analysis methods were also applied to obtain hetero morphological structure of materials. The fractal analysis results indicated that carbon nanotube doping to the standard sample increases the coating rates, scalability and heterogeneity of the solid phase surface of the sample. The coating rates of composite surfaces were calculated as 45% and 36%, respectively. Morphology analysis revealed that the probability of finding surface particles for the nanotube-doped sample decreased compared to the undoped sample, but the fractal dimension value increased. While this value was 1.83 in the pure sample, it increased to 1.92 in the nanotube material.

Novel adaptive control approach to fractal fractional order deforestation model and its impact on soil erosion.

Deforestation exerts profound ramifications on soil quality and biodiversity, thereby exerting substantial economic repercussions. The depletion of organic matter and structural integrity of soil following tree removal for agricultural purposes underscores the severity of this issue. In elucidating the soil pollution stemming from deforestation, this research employs a sophisticated five-compartment SDIFR model integrating fractal dimension and fractional order dynamics. The rigorous analysis, including the application of Picard Lindelof's fixed point theorem, establishes the existence and uniqueness of explicit solutions. Furthermore, the examination of local and global stability sheds light on the system's behavior, delineating between pollution-free equilibrium and pollution-extinct equilibrium states. To regulate system behavior, an adaptive control framework grounded in fractal fractional order is proposed, leveraging the Adams-Bashforth numerical approximation scheme for implementation. Through numerical simulations, the study underscores the pivotal role of parameters, thus substantiating the significance of the proposed model in comprehensively addressing the complexities of soil pollution induced by deforestation.

AFM Nanoindentation of Stiff Inhomogeneous Layer onPolymeric Substrate.

Analysis of indentation data of heterogeneous material, in particular, layer on an elastic substrate requires information about the contact area that is essential for calculating mechanical properties. The actual shape of the AFM-tip is not described by simple body of revolution. In this work, the indentation of a stiff layer on a hyperelastic substrate by a truncated conical tip is studied using finite element methods. The size of the tip, elastic modulus, and thickness of the layer are varied. The obtained model dependences of loading and contact area versus the depth of indentation are used in analysis of the experimental data of AFM indentation of stiff inhomogeneous nanolayers of polyurethane surface. Thickness and elastic modulus of the layers, fracture properties of the surface are studied. The obtained results can find application in the study of mechanical properties and fracture toughness of thin flexible films on an elastic substrate.

Relationship Between Salt Accumulation and Soil Structure Fractals in Cotton Fields in an Arid Inland Basin

The relationship between soil structure and salt accumulation is unclear; thus, experiments on salt accumulation under different soil structures were conducted in cotton fields in arid areas of northwest China. Thirty-nine sets of soil samples were collected from the 0 to 180 cm profile of three experimental areas. The total salt content of the soil extracts and the particle size distribution of the soil samples were determined using a JENCO TDS and a laser particle size analyzer, respectively, and the fractal dimension of the soil structure was obtained using fractal theory. Pearson’s correlation analysis and Tukey’s test (p &lt; 0.01) were used to analyze the correlation between soil salinity, soil particle size distribution, and fractal dimensions in the three profiles. The results showed soil salinity accumulation was affected mutually by soil texture and soil structure, and soil salinity tended to accumulate in fine-grained soil. The soil fractal dimension (D) could indicate soil texture and quantify soil salinity content. When the sand content was more than 50%, there was a significant positive correlation between the soil fractal dimension and soil salinity (correlation coefficient R = 0.943). The results provide valuable insights into cotton production in arid areas.

Pore-throat structure, fractal characteristics and permeability prediction of tight sandstone: the Yanchang Formation, Southeast Ordos Basin.

As a typical tight reservoir and an important site for unconventional hydrocarbon accumulation, the Chang 6 member of the Yanchang Formation is characterized by complex pore structures and strong heterogeneity. Analysing and characterizing the pore-throat structure is highly important for optimizing oil recovery processes. To clarify the nonhomogeneity and structural characteristics of the pore throats in the southeastern Ordos Basin, tight sandstone from the Chang 6 member was selected for analysis. Casting thin section (CTS), scanning electron microscopy (SEM), cathodoluminescence (CL), X-ray diffraction (XRD), and mercury intrusion capillary pressure (MICP) analyses were conducted. The results, revealed that intergranular pores, feldspar-dissolved pores, intergranular-dissolved pores, and microfractures were the predominant pore types found within the samples. By combining the results of MICP analysis with those of fractal theory, the pore-throat structure of each sample can be categorized into two types: large-scale and small-scale. Fractal theory was employed to characterize the complex and irregular pore-throat structure of the reservoir quantitatively. The average fractal dimension of large pores (D1) was 2.8094, whereas for small pores (D2), it was slightly lower than that of large pores, averaging 2.5325. These findings underscore that large-scale pore-throat structures are more complex and exhibit greater heterogeneity. Compared with those of large pores, the pore-throat structure parameters of small pores exhibit a more significant correlation with reservoir properties and fractal dimensions. Therefore, small pores are the primary contributors to the reservoir storage space and are key factors influencing the pore-throat structure of the Chang 6 tight sandstone. Based on the pore-throat radius and considering the influence of fractal characteristics on the pore structure, a nonlinear permeability prediction model was created using multiple regression analysis. Among these equations, the pore-throat radius corresponding to a mercury saturation of 40% (r40) emerged as the most effective predictor of permeability for tight sandstone. The investigation of micropore-throat structures in tight oil reservoirs holds practical significance for comprehending the distribution and accumulation of tight oil and guiding oil field development.

Interfaces of the two-dimensional voter model in the context of SLE

Abstract This paper investigates various geometrical properties of interfaces of the two-dimensional voter model. Despite its simplicity, the model exhibits dual characteristics, resembling both a critical system with long-range correlations, while also showing a tendency towards order similar to the Ising–Glauber model at zero temperature. This duality is reflected in the geometrical properties of its interfaces, which are examined here from the perspective of Schramm–Loewner evolution. Recent studies have delved into the geometrical properties of these interfaces within different lattice geometries and boundary conditions. We revisit these findings, focusing on a system within a box of linear size L with Dobrushin boundary conditions, where values of the spins are fixed to either +1 or −1 on two distinct halves of the boundary, in order to enforce the presence of a pinned interface with fixed endpoints (or chordal interface). We also expand the study to compare the geometrical properties of the interfaces of the voter model with those of the critical Ising model and other related models. Scaling arguments and numerical studies suggest that, while locally the chordal interface of the voter model has fractal dimension d f = 3 / 2 , corresponding to a parameter κ = 4, it becomes straight at large scales, confirming a conjecture made by Holmes et al (2015 J. Stat. Phys. 159 937–57), and ruling out the possibility of describing the chordal interface of the voter model by SLE κ , for any non-zero value of κ. This contrasts with the critical Ising model, which is described by SLE3, and whose interface fluctuations remain of order L, and more generally with related critical models, which are in the same universality class.

Effects of different sand fixation plantations on soil properties in the Hunshandake Sandy Land, Eastern Inner Mongolia, China.

Planting forests is an effective way to improve desertification. In order to elucidate the impacts of different vegetation types on soil development and restoration of degraded lands, we compared the properties of soils at different depths in three plantation forests in the Hunsandak Sandy Land in the Chinese agro-pastoral ecotone (Ulmus pumila, Pinus sylvestris var. mongolica, and Populus simonii). The results show that all three plantation forests were able to significantly improve the soil properties, and they resulted in soil nutrient enrichment in the surface layer. As the soil depth increased, the soil became progressively poorer in nutrients, the fine particle content decreased, and the bulk density and water content increased. The orders of the fractal dimension characterization and soil improvement effects of the different tree species were as follows: U. pumila > P. sylvestris var. mongolica > P. simonii. Compared with the bare sand, the soil bulk density under the U. pumila plantation was 19% lower; the soil water content was 74% higher; the soil organic matter, total N, P, and K were 336%, 207%, 106%, and 31% higher; the available N, P, and K were 41%, 125%, and 21% higher; and the clay and silt contents were 498% and 387% higher, respectively. The ranges of the soil fractal dimension were 1.67-2.08 for the bare sandy land and 2.14-2.32 for the planted forests. The soil fractal dimension was strongly correlated with the soil physicochemical properties, especially with the soil nutrients and fine particle content, which exhibited highly significant correlations (p < 0.01), and the correlation coefficients were all greater than 0.8. Therefore, we believe that U. pumila is a suitable sand-fixing plant species in this area. In addition, the soil fractal dimension can be used as an important reference index for characterizing soil properties in sandy areas.

Computational model for fractal dimension of anisotropic gear surfaces based on improved structure function method

Computational model for fractal dimension of anisotropic gear surfaces based on improved structure function method

Abstract 4113951: Calcification Alters Luminal Surface Complexity in Cadaveric Left Anterior Descending Arteries

Background: Understanding the intricacies of luminal surface topographic changes in pathologic coronary arteries may yield insight not only on the efficacy of existing clinical interventions (e.g. impact of surface changes on stent anchoring), but also on the subsequent hemodynamic changes and pathophysiology of thrombus formation. In this study, we aim to detect and quantify luminal surface alterations induced by the presence of calcification in cadaveric left anterior descending arteries (LADs) using a novel approach–surface metrology. Methods: LADs (n=10) were harvested from cadaveric hearts using a systematic dissection approach, scanned using the Bruker Skyscan 1173 microCT scanner, and then underwent threshold-based image segmentation on Dragonfly by Object Research Systems to quantify the total calcium volume present throughout the vessel. Each specimen was then splayed open and up to 15 scans were performed at 20X magnification using the Sensofar S Neox optical profiler. Each scan subsequently underwent surface metrologic scale-sensitive fractal analyses in SensoMap 10. Results: Extent of calcification was standardized and expressed using the following ratio: total calcium volume by total vessel length (TC/VL). We considered a TC/VL ratio of 0-0.25 as low calcification and 0.26-0.5 as high calcification. Interestingly, our findings demonstrated statistically significant increases in smooth-rough crossover (SRC) and scale of maximum complexity (Smfc) with positive correlation, but reductions in fractal complexity (Lsfc) and fractal dimension (Dls) with negative correlation, in highly calcified compared to lowly calcified LADs. Conclusions: Our data suggests that the presence of calcium in the walls of LADs may translate to increased roughness in luminal surfaces generally, but smoothness over calcified plaques, locally. Our proposed mechanism is increased endothelial tension directly over areas of calcification, thus reducing surface complexity. Future studies will involve modeling blood flow using smooth particle hemodynamics (SPH) based on complete luminal and surface topographical geometries to evaluate the impact of these surface changes on hemodynamics.

Fractal dimensions of fractal transformations and quantization dimensions for bi-Lipschitz mappings

In this paper, we study the fractal dimension of the graph of a fractal transformation and also determine the quantization dimension of a probability measure supported on the graph of the fractal transformation. Moreover, we estimate the quantization dimension of the invariant measure corresponding to a weighted iterated function system consisting of bi-Lipschitz mappings under the strong open set condition.

Fractal dimension, lacunarity, and bone area fraction analysis of peri-implant trabecular bone after prosthodontic loading.

To assess the structural alterations in peri-implant bone occurring 5years after prosthodontic loading in panoramic radiography (PR). PR images of 44 mandibular and 33 maxillary implants along with 42 healthy control teeth taken before and 5years after prosthodontic loading were included. Two regions-of-interest (ROI) were selected from mesial and distal surrounding bone of each implant and tooth. Then, the selected ROIs were divided to obtain three sub-ROIs (coronal, middle, and apical) on each side. A total of eight ROIs and sub-ROIs from each implant and control tooth were used for the calculations of fractal dimension (FD), lacunarity, and bone area fraction (BA/TA). The paired-sample t test was used to compare measurements before and 5years after loading (p = 0.05). Overall evaluation of 77 implants showed that FD decreased at the middle and apical peri-implant bone levels 5years after loading (p < 0.05). In mandibular implants, BA/TA decreased after loading (p < 0.05). While FD decreased at the coronal level (p = 0.022), lacunarity increased at the middle level of mandibular implants (p < 0.05). In maxillary implants, FD decreased at the middle and BA/TA decreased at the coronal level (p < 0.05). On the other hand, BA/TA increased at the apical level of maxillary implants (p = 0.016) after loading. None of the parameters revealed any difference in the control group (p > 0.05). FD and BA/TA can be used to analyze structural changes in peri-implant bone after prosthodontic loading. Additionally, FD, lacunarity and BA/TA may provide useful information about changes occurring at different levels of peri-implant bone.

A Novel Approach for Time-Local Fractional Solutions of Certain Nonlinear Partial Differential Equations in Fractal Dimension

Time-local fractional approaches for nonlinear partial differential equations in fractal dimensions are essential for capturing the complex, irregular behaviors found in fractal systems. In this paper, a new modification of the local fractional Laplace variational iteration method (MLFLVIM) for obtaining analytical approximate solutions to the fractional gas dynamics equation, fractional Stefan equation, and fractional Newell-Whitehead-Segel equation within the context of fractal time space is presented. The proposed method (MLFLVIM) elegantly combines the local fractional Laplace transform (LFLT) with modified variational iteration method. Specifically, we first apply the (LFLT) to the given local fractional PDEs, yielding a transformed system of equations. We then apply modified variational iteration to this system. Finally, we use the inverse of (LFLT) to obtain the desired solution. To demonstrate the effectiveness of this approach, we implement it on three numerical physical problems. The results show that the (MLFLVIM) can successfully handle these nonlinear LFPDEs and provide accurate analytical approximation solutions.

Fractal Geometry in Vertebrate Respiratory Systems: A Comparative Analysis of Branching Patterns Across Species

This study investigates the application of fractal geometry to the analysis of vertebrate respiratory systems, focusing on the branching patterns of the bronchial tree across diverse species. Using a combination of mathematical modeling and computational visualization, we explore how fractal dimensions and branching characteristics reflect evolutionary adaptations to various habitats and physiological demands. The research encompasses a range of vertebrates, including humans, horses, dolphins, chickens, iguanas, and bullfrogs, representing diverse taxonomic groups and ecological niches. Our analysis reveals a clear gradient of complexity in respiratory structures, correlating strongly with metabolic rates and environmental adaptations. Mammals, particularly those adapted for high‐performance activities like horses, demonstrate the most complex fractal patterns, indicating highly efficient gas exchange systems. In contrast, ectothermic species such as iguanas and bullfrogs exhibit simpler structures, reflecting their lower metabolic demands and alternative respiratory strategies. The study employs fractal dimension calculations, L‐system modeling, and lacunarity analysis to quantify and visualize these differences. Our findings suggest that fractal analysis provides valuable insights into the relationship between form and function in vertebrate respiratory systems, offering a novel perspective on comparative physiology and evolutionary biology. This research not only enhances our understanding of respiratory system evolution but also has potential applications in biomimetic design, medical diagnostics, and ecological physiology. It demonstrates the power of interdisciplinary approaches, combining advanced mathematics with biological principles to uncover fundamental patterns in nature.

Research on mechanical properties and pore structure evolution process of steam cured high strength concrete under freeze thaw cycles.

With the widespread use of high-strength concrete structures (HC), the impact of pore structure on their performance has become a current research focus. The mechanism by which different curing conditions and freeze-thaw cycles influence the evolution of pore structure remains unclear. Therefore, this study systematically investigated the frost resistance of high-strength concrete under different curing conditions, measured the mass loss rate, compressive strength, and relative dynamic elastic modulus of concrete under freeze-thaw cycles. Utilizing low-field nuclear magnetic resonance (NMR) technology, this study analyzed the evolution of pore structure in HC under freeze-thaw cycles. Additionally, the fractal dimension was used to evaluate the change of concrete internal pore structure, so as to reflect the influence of pore structure on the mechanical properties of concrete subjected to freeze-thaw cycles, and then evaluated the freeze-thaw damage of HC. The experimental results indicated that the steam curing regimes led to an increase in the porosity of HC, thereby influencing its frost resistance. Steam-cured high-strength concrete (SMHC) exhibited a higher degradation rate under freeze-thaw cycles, resulting in a greater level of deterioration compared to standard curing high-strength concrete (SDHC), even under the same number of freeze-thaw cycles.

The impact of the type of playful massage movements on the perception of tactile stimulation in children: EEG study

Tactile play and playful massage are a normal interaction between adults and children in many cultures. Experimental data show that activation of the C-tactile system during such playful touches contributes to children’s socialization and the establishment of psychoemotional bonds in the parent-child dyad. However, comprehensive studies of the effects of different types of touch on perception of tactile stimulation in children have not been conducted before. Twenty-three children participated in the present study: 10 in the preschool age group and 13 in the elementary school age group. Children in both groups received play massage containing different types of touch with simultaneous recording of electroencephalogram (EEG) and heart rate. EEG processing included determination of spectral power, alpha rhythm peak frequency and fractal dimension. Analysis of the results showed that the relaxing effect of the procedure was more pronounced in children of primary school age, which can be explained both by the greater maturity of the CNS and the greater need for tactile contact, which is not realized in the school environment.