shape accuracy
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Aims: The accuracy of non-radiographic measurement of the spinal shape is infl uenced by postural sway (PS).The aim of this study was to determine whether certain examination postures prevent PS without changing key spinalcharacteristics. Methods: We tested 1) natural standing position (posture A), 2) fi xation postures standing with the support of theupper limbs against a wall (posture B) and 3) standing with the support of the head and chest against a wall (postureC). There were examined 60 subjects; the examination of each posture was repeated fi ve times in each individual byDTP-3 microcomputer position system. The spinal shape changes resulting from tested postures were assessed usingt-test. The role of PS was assessed using standard deviations, and the signifi cance of diff erences between the individualpostures was determined using the F-test. Results: Compared to posture A, the fi xation posture B did not have any signifi cant infl uence on the degree of PS,but it signifi cantly infl uenced the shift of the spine from the ideal vertical and its slope, although this did not result inspine curve deformation. The fi xation posture C signifi cantly reduced the PS compared to posture A; however, therewere signifi cant changes in the spinal shape. This fi xation posture shifted signifi cantly the spine from the ideal verticaland slope characteristics.Conclusion: PS plays a role in the examination of spinal shape. Positions B and C did not meet the required criteria.Therefore, it is necessary to search for another examination position.
- MeSH
- diagnostické techniky a postupy využití MeSH
- experimenty na lidech MeSH
- financování organizované MeSH
- lidé MeSH
- mikropočítače využití MeSH
- muskuloskeletální systém - fyziologické jevy MeSH
- postura těla fyziologie MeSH
- posturální rovnováha MeSH
- statistika jako téma MeSH
- zakřivení páteře diagnóza etiologie MeSH
- zobrazování trojrozměrné metody přístrojové vybavení využití MeSH
- Check Tag
- lidé MeSH
Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies.
PURPOSE OF STUDY Aseptic loosening of total joint replacement (TJR) due to wear of ultra-high molecular weight polyethylene (UHMWPE) is regarded as one of the major problems in the field of arthroplasty. This work describes a newly developed method, cal- led MORF, which completely describes the morphology of UHMWPE wear particles. The differences in wear particle mor - phology may help to elucidate individual differences in TJR failures. MATERIAL AND METHODS During the years 2002-2010, a set of 47 typical damaged periprosthetic tissues, coming from 16 TJR revisions, was col- lected. Isolated on polycarbonate (PC) filters were quantified. Quantification of the particles consisted in determination of their concentration and description of their morphology by means of the newly developed MORF method. Firstly, the mic- rographs of isolated UHMWPE particles were obtained with a scanning electron microscope (Quanta 200 FEG; FEI) at two magnifications: x1200 and x6000. Secondly, both high- and low-magnification micrographs were processed by a standard image analysis software (program NIS Elements; Laboratory Imaging) in order to obtain basic morphological descriptors. Finally, the results from image analysis of high- and low- magnification micrographs were combined by means of our own program MDISTR in order to obtain correct particle sizes and shapes. RESULTS In the first stage, the method was applied to 25 samples and yielded an average particle size of 0.51 µm. In the second stage, the method was further improved in order to calculate not only the size of particles but also the shape of descrip- tors. The improved method was applied to eight samples and gave an average size of particles (equivalent diameter, D) in the range of 0.27 - 0.60 µm, circularity (C) of 0.66-0.85 and elongation (E) of 1.75-1.79, suggesting that the great majori- ty of particles were approximately spherical. Finally, in the third stage, the MORF method was applied to two exceptional samples which contained extremely small wear particles (D = 18.5 nm and 21.2 nm). The shape of these small wear nano- particles (C = 0.97 and 0.93; E = 1.29 and 1.35) was even more spherical than that of wear microparticles described abo- ve. This was one of the first two studies which proved the presence of UHMWPE wear nanoparticles in vivo. DISCUSSION Our newly developed MORF method described in this contribution yields both size and shape descriptors of UHMWPE wear particles, with sizes from 0.1 to 10 µm, which are regarded as most biologically active. The main objective of the met- hod is to yield the highest accuracy. This is achieved by parallel analyses of high- and low-magnification micrographs taken of the same sample. In the end, the two analyses are combined together in order to obtain the correct and complete size and shape description of all particles in the sample. The morphology of UHMWPE wear particles influences TJR lifetime both directly (size and shape of the particles is related to their biological activity) and indirectly (for the given total volu- metric wear, size and shape of the particles influence their concentration, which is associated with the biological respon- se of the organism). CONCLUSION The authors have developed a new method which yields a complete description of the size and shape of UHMWPE wear particles in periprosthetic tissues. The method, which was called MORF, can be applied to studies of TJR failures and also used to evaluate the quality of different UHMWPE components of TJR. The method is quite universal and therefore can be used not only for analyses of wear particles, but also for other types of particles, such as microparticles in polymer blends or inorganic/metallic nanoparticles. Key words: UHMWPE, wear debris, total joint replacement, morphology of wear particles.
- MeSH
- analýza selhání vybavení MeSH
- financování organizované MeSH
- kyčelní kloub patologie MeSH
- kyčelní protézy MeSH
- lidé MeSH
- mikroskopie elektronová rastrovací MeSH
- náhrada kyčelního kloubu MeSH
- nanočástice MeSH
- počítačové zpracování obrazu MeSH
- polyethyleny MeSH
- velikost částic MeSH
- Check Tag
- lidé MeSH
The aims of this study were to enable geometric morphometric sex classification using tibial proximal and distal sexual dimorphism and to evaluate the secular trend of tibial shape/form from the early 20th century to the present day. The study samples consisted of 61 adult tibias from an early 20th-century Czech population and 57 three-dimensional tibias from a 21st-century population. Discriminant function analysis with cross-validation was carried out to assess the accuracy of sex classification. Shape analysis revealed significant sex differences in both tibial extremities of the 21st-century sample and in the proximal tibia of the 20th-century population. Sex-based divergence varied between the analyzed samples, raising the issues of population specificity and diachronic change. Classification using tibial form was more successful than using tibial shape. The highest values of correct assignment (91.80% and 88.52%) were found using the form from the early 20th Czech population.
- MeSH
- analýza hlavních komponent MeSH
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- diskriminační analýza MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- počítačová rentgenová tomografie MeSH
- senioři MeSH
- soudní antropologie MeSH
- tibie anatomie a histologie radiografie MeSH
- určení pohlaví podle kostry metody MeSH
- zobrazování trojrozměrné MeSH
- Check Tag
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- historické články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
In order to improve the h-index in terms of its accuracy and sensitivity to the form of the citation distribution, we propose the new bibliometric index [symbol in text]. The basic idea is to define, for any author with a given number of citations, an "ideal" citation distribution which represents a benchmark in terms of number of papers and number of citations per publication, and to obtain an index which increases its value when the real citation distribution approaches its ideal form. The method is very general because the ideal distribution can be defined differently according to the main objective of the index. In this paper we propose to define it by a "squared-form" distribution: this is consistent with many popular bibliometric indices, which reach their maximum value when the distribution is basically a "square". This approach generally rewards the more regular and reliable researchers, and it seems to be especially suitable for dealing with common situations such as applications for academic positions. To show the advantages of the [symbol in text]-index some mathematical properties are proved and an application to real data is proposed.
BACKGROUND: Although the etiology of chronic lymphocytic leukemia (CLL), the most common type of adult leukemia, is still unclear, strong evidence implicates antigen involvement in disease ontogeny and evolution. Primary and 3D structure analysis has been utilised in order to discover indications of antigenic pressure. The latter has been mostly based on the 3D models of the clonotypic B cell receptor immunoglobulin (BcR IG) amino acid sequences. Therefore, their accuracy is directly dependent on the quality of the model construction algorithms and the specific methods used to compare the ensuing models. Thus far, reliable and robust methods that can group the IG 3D models based on their structural characteristics are missing. RESULTS: Here we propose a novel method for clustering a set of proteins based on their 3D structure focusing on 3D structures of BcR IG from a large series of patients with CLL. The method combines techniques from the areas of bioinformatics, 3D object recognition and machine learning. The clustering procedure is based on the extraction of 3D descriptors, encoding various properties of the local and global geometrical structure of the proteins. The descriptors are extracted from aligned pairs of proteins. A combination of individual 3D descriptors is also used as an additional method. The comparison of the automatically generated clusters to manual annotation by experts shows an increased accuracy when using the 3D descriptors compared to plain bioinformatics-based comparison. The accuracy is increased even more when using the combination of 3D descriptors. CONCLUSIONS: The experimental results verify that the use of 3D descriptors commonly used for 3D object recognition can be effectively applied to distinguishing structural differences of proteins. The proposed approach can be applied to provide hints for the existence of structural groups in a large set of unannotated BcR IG protein files in both CLL and, by logical extension, other contexts where it is relevant to characterize BcR IG structural similarity. The method does not present any limitations in application and can be extended to other types of proteins.
The greater sciatic notch (GSN) is one of the most important and frequently used characteristics for determining the sex of skeletons, but objective assessment of this characteristic is not without its difficulties. We tested the robustness of GSN sex classification on the basis of geometric morphometrics (GM) and support vector machines (SVM), using two different population samples. Using photographs, the shape of the GSN in 229 samples from two assemblages (documented collections of a Euroamerican population from the Maxwell Museum, University of New Mexico, and a Hispanic population from Universidad Nacional Autónoma de México, Mexico City) was segmented automatically and evaluated using six curve representations. The optimal dimensionality for each representation was determined by finding the best sex classification. The classification accuracy of the six curve representations in our study was similar but the highest and concurrently homologous cross-validated accuracy of 92% was achieved for a pooled sample using Fourier coefficient and Legendre polynomial methods. The success rate of our classification was influenced by the number of semilandmarks or coefficients and was only slightly affected by GSN marginal point positions. The intrapopulation variability of the female GSN shape was significantly lower compared with the male variability, possibly as a consequence of the intense selection pressure associated with reproduction. Males were misclassified more often than females. Our results show that by using a suitable GSN curve representation, a GM approach, and SVM analysis, it is possible to obtain a robust separation between the sexes that is stable for a multipopulation sample.
- MeSH
- analýza hlavních komponent MeSH
- antropologie fyzická metody MeSH
- lidé MeSH
- pánevní kosti anatomie a histologie MeSH
- pohlavní dimorfismus MeSH
- reprodukovatelnost výsledků MeSH
- support vector machine MeSH
- určení pohlaví podle kostry metody MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Previous studies have shown that homosexual men differ from heterosexual men in several somatic traits and lay people accurately attribute sexual orientation based on facial images. Thus, we may predict that morphological differences between faces of homosexual and heterosexual individuals can cue to sexual orientation. The main aim of this study was to test for possible differences in facial shape between heterosexual and homosexual men. Further, we tested whether self-reported sexual orientation correlated with sexual orientation and masculinity-femininity attributed from facial images by independent raters. In Study 1, we used geometric morphometrics to test for differences in facial shape between homosexual and heterosexual men. The analysis revealed significant shape differences in faces of heterosexual and homosexual men. Homosexual men showed relatively wider and shorter faces, smaller and shorter noses, and rather massive and more rounded jaws, resulting in a mosaic of both feminine and masculine features. In Study 2, we tested the accuracy of sexual orientation judgment from standardized facial photos which were assessed by 80 independent raters. Binary logistic regression showed no effect of attributed sexual orientation on self-reported sexual orientation. However, homosexual men were rated as more masculine than heterosexual men, which may explain the misjudgment of sexual orientation. Thus, our results showed that differences in facial morphology of homosexual and heterosexual men do not simply mirror variation in femininity, and the stereotypic association of feminine looking men as homosexual may confound judgments of sexual orientation.
- MeSH
- dospělí MeSH
- heterosexualita * MeSH
- homosexualita mužská * MeSH
- lidé MeSH
- mínění MeSH
- mužskost MeSH
- obličej * MeSH
- obličejové kosti anatomie a histologie MeSH
- pohlavní dimorfismus * MeSH
- sexuální chování MeSH
- ženskost MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The aim of the work was to analyze the influence of process parameters of high shear granulation on the process yield and on the morphology of granules on the basis of dynamic image analysis. The amount of added granulation liquid had a significant effect on all monitored granulometric parameters and caused significant changes in the yield of the process. In regard of the shape, the most spherical granules with the smoothest surface were formed at a liquid to solid ratio of ≈1. The smallest granules were formed at an impeller speed of 700 rpm, but the granules formed at 500 rpm showed both the most desirable shape and the highest process yield. Variation in the shape factors relied not only on the process parameters, but also on the area equivalent diameter of the individual granules in the batch. A linear relationship was found between the amount of granulation liquid and the compressibility of the granules. Using response surface methodology, models for predicting the size of granules and process yield related to the amount of added liquid and the impeller speed were generated, on the basis of which the size of granules and yield can be determined with great accuracy.
- Publikační typ
- časopisecké články MeSH
Reputational peer nominations are a common method for measuring involvement in aggression-related behaviors, encompassing the roles of aggressor, victim, and defender, but may be influenced by students' affective (dis)liking relationships. This social network study investigated whether dyad- and group-level (dis)liking relationships affect perceptions of classmates' involvement in physical aggression and explored the moderating roles of classroom moral disengagement and defending norms. The study employed a longitudinal design with two time points 6 months apart, encompassing 27 classrooms and 632 early adolescents. Using multiplex stochastic actor-oriented modeling, we found that liking, but not disliking, significantly influenced perceptions. Liking a classmate increased the likelihood of perceiving them as a defender. Moreover, students' own perceptions (aggressor, victim, and defender nominations) were shaped by the perceptions of classmates they liked, while classroom moral disengagement reduced this influence for defender nominations. Results on classroom defending norms were mixed. Our findings underscore the importance of accounting for students' liking relationships and classroom-level norms to reduce bias in peer nominations and improve the accuracy of assessments of aggression-related behaviors.
- MeSH
- afekt MeSH
- agrese * psychologie MeSH
- chování mladistvých psychologie MeSH
- dítě MeSH
- interpersonální vztahy * MeSH
- lidé MeSH
- longitudinální studie MeSH
- mladiství MeSH
- oběti zločinu * psychologie MeSH
- školy MeSH
- sociální normy MeSH
- sociální percepce * MeSH
- studenti psychologie MeSH
- vyrovnaná skupina * MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
