Comparison of computational pose estimation models for joint angles with 3D motion capture

Tools to calculate human movement patterns can benefit musculoskeletal clinicians and researchers for rehabilitation assessments. The research objective of this study was to compare two human pose estimation models (HRNet, MediaPipe) against the laboratory marker-based reference standard for joint angles and range of motion (ROM) for several movement parameters. Twenty-two healthy volunteers (Female n=16, Male n=6), participated to compare outputs for knee and elbow kinematics. Joint angles were calculated by selecting three marker points defining the joint and angle between them in Qualisys Track Manager software. Using predicted key points, pose estimation model calculations for the same musculoskeletal kinematic outputs were computed. Coefficient of Variation (CoV) was used as a variation statistic for joint angle during movements. All comparison results were under 10%, implying that both models compute reliable joint angle data during the five tested activities. When comparing ROM as a discrete parameter, CoV values remain low, though not all below 10%. Intra-class Correlation Coefficients were computed across the ROM data as a measure of statistical similarity. Each exercise displayed good-excellent and significant correlations for both models compared to Qualisys apart from left knee sit-to-stand. Exploration from this data sampling imply that flexion/extension exercises give stronger consistency results than full sit-to-stand movements when compared to 3D motion analysis, and there is little distinction between these two models. Finer tuning of models will give further reliability for in-depth analysis as these results are restricted, but valuable for a rehabilitative setting with limited objective analysis alternative

Characterization of Zahari Zograph's nave wall paintings in the church "The nativity of the virgin" of Rila Monastery (Bulgaria) by vibrational spectroscopy and SEM-EDX analysis

An analytical study on the nave mural paintings of the church “The Nativity of the Virgin” of Rila monastery, Bulgaria, painted by Zahari Zograph was carried out. Vibrational spectroscopy was applied to identify the pigments and organic materials used in the mural paintings. To complement the spectral information, elemental composition of the samples was determined by SEM-EDX. The data showed that smalt with carbohydrate binder was applied for the blue background, green colour was executed by green earths and red-orange colour – by red lead. Azurite is the pigment used to paint the blue colour of the saints’ hoods. The mordant for gilding was prepared of drying oil, resin and siccative metal oxides as evidenced by SEM-EDX, ATR-FTIR and pyrolysis GC-MS analysis. The use of azurite is related to Zahari Zograph’s works as it was not found in any of the previously studied murals in the church painted by other artists

Polished decorative fields in Thracian fresco tombs from the Hellenistic period - archaeometrical research

In order to gather information on the technological characteristics of the monochrome decorative wall plasters in some Thracian fresco tombs (4th -3rd centuries BC) found in South Bulgaria, several types of analyses have been carried out. Samples of red, yellow and white large wall-painted fields in different monuments, have been investigated using a combination of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Differential Scanning Calorimetry (DSC) to identify the organic components of the paint layer. The nature of the pigments has been determined both by X-ray diffraction (XRD) and ATR-FTIR. The obtained results point towards the recognition of final polishing processes performed on still wet plaster. This technique of creating polished wall painted surfaces in combination with organic coatings (known as stucco lustro) is traditionally associated with the Pompean frescoes and the work of roman painters. Based on the technical examination, it can be assumed that in pre-roman time, the Hellenistic paint-craftsmen in Thrace inland were also familiar to this technique

Structural diversity, but no polymorphism, in a homologous family of co-crystals of urea and α,ω-dihydroxyalkanes

A family of stoichiometric (2:1 molar ratio) co-crystals formed between urea and α,ω-dihydroxyalkanes of even chain length [HO(CH2)nOH, n = 2m, m = 3–8] is shown to exhibit three well-defined structure types, which are rationalized on the basis of specific hydrogen-bonding motifs. In spite of the structural diversity observed for different α,ω-dihydroxyalkane chain lengths, there is no evidence that any member of this family of co-crystals exhibits polymorphism (i.e. none of the α,ω-dihydroxyalkane/urea systems is observed to exist in more than one of the well-defined co-crystal structure types)