Automorphisms of Algebraic Curves

Στην παρούσα διατριβή μελετώνται οι αυτομορφισμοί αλγεβρικών καμπυλών επί σωμάτων θετικής χαρακτηριστικής. Μετά από μια σύντομη περιγραφή μιας κλάσης καμπυλών γνωστών ως καμπύλες Harbater-Katz-Gabber αποδεικνύεται μια σειρά νέων αποτελεσμάτων για αυτές τις καμπύλες. Στη συνέχεια υπολογίζεται το κανονικό ιδεώδες μιας τέτοια καμπύλης. Στις τελευταίες παράγραφους δίνονται αποτελέσματα που αφορούν γενικές αλγεβρικές καμπύλες και σχετίζονται με το κανονικό ιδεώδες και με τη θεωρία των συζυγιών.In this dissertation automorphisms of algebraic curves in positive characteristic are studied. After a brief outline of a class of curves known as Harbater-Katz-Gabber curves, some new results regarding these curves are proven. After that the canonical ideal of such a curve is calculated. In the last paragraphs we present results concerning general algebraic curves and are related to the canonical ideal and the theory of syzygies

Notch Signaling Pathway in Tooth Shape Variations throughout Evolution

Evolutionary changes in vertebrates are linked to genetic alterations that often affect tooth crown shape, which is a criterion of speciation events. The Notch pathway is highly conserved between species and controls morphogenetic processes in most developing organs, including teeth. Epithelial loss of the Notch-ligand Jagged1 in developing mouse molars affects the location, size and interconnections of their cusps that lead to minor tooth crown shape modifications convergent to those observed along Muridae evolution. RNA sequencing analysis revealed that these alterations are due to the modulation of more than 2000 genes and that Notch signaling is a hub for significant morphogenetic networks, such as Wnts and Fibroblast Growth Factors. The modeling of these tooth crown changes in mutant mice, via a three-dimensional metamorphosis approach, allowed prediction of how Jagged1-associated mutations in humans could affect the morphology of their teeth. These results shed new light on Notch/Jagged1-mediated signaling as one of the crucial components for dental variations in evolution

The Effect of Body Mass on the Shoe-Athlete Interaction

Long-distance running is known to induce joint overloading and elevate cytokine levels, which are the hallmarks for a variety of running-related injuries. To address this, footwear systems incorporate cushioning midsoles to mitigate injurious mechanical loading. The aim of this study was to evaluate the effect of athlete body mass on the cushioning capacity of technical footwear. An artificial heel was prototyped to fit the impact pattern of a heel-strike runner and used to measure shock attenuation by an automated drop test. Impact mass and velocity were modulated to simulate runners of various body mass and speeds. The investigation provided refined insight on running-induced impact transmission to the human body. The examined midsole system was optimized around anthropometric data corresponding to an average (normal) body mass. The results suggest that although modern footwear is capable of attenuating the shock waves occurring during foot strike, improper shoe selection could expose an athlete to high levels of peak stress that could provoke an abnormal cartilage response. The selection of a weight-specific cushioning system could provide optimum protection and could thus prolong the duration of physical exercise beneficial to maintaining a simulated immune system

Применение сверточной нейронной сети U-Net для сегментации текстовых областей на изображениях реальных сцен

Micro-blasting on PVD films has been documented, among others, as an efficient method for inducing compressive stresses, thus for increasing the coating hardness and potentially tool life of coated tools. Since contradictory results have been registered concerning the efficiency of wet micro-blasting on coated tools for improving the wear behaviour, the paper aims at explaining how this process can be successfully applied for post-treatment of PVD films. In this context, the employed conditions such as pressure and grain size affect significantly the wear resistance of the micro-blasted coated tools.In the described investigations, TiAlN coatings were post-treated through wet micro-blasting by Al2O3 abrasives of various grains' diameter. Abrasion mechanisms after micro-blasting were investigated by roughness measurements. Nanoindentations on micro-blasted film surfaces at various pressures revealed the influence of this process on coating superficial hardness. The relat ed residual stress changes were estimated considering the film yield stress alterations, which were analytically determined, based on nanoindentation results. Nano-impact tests were conducted for investigating the effect of the developed film compressive stresses at certain micro-blasting pressures and grain sizes on the film's brittleness. To monitor film thickness and cutting edge radius changes of coatings subjected to micro-blasting, ball cratering tests and white light scans were carried out respectively. In this way, micro-blasting conditions for improving the film hardness, without revealing the substrate in the cutting edge region, were detected. Finally, the wear behaviour of coated and variously wet micro-blasted tools was investigated in milling of hardened steel

A sensitivity study of human mandibular biting simulations using finite element analysis

The form of human mandible reflects both genetic history and loading. In the context of archaeology, it has been used to retrodict loading history as a means of inferring subsistence strategy and paramasticatory use of the dentition. Rather than relying on form to retrodict function, an alternative is to simulate function and compare performance. Finite element analysis (FEA) offers the prospect of predicting and comparing the performance of mandibles under specific loading scenarios, for instance, simulated biting. However, its application depends on the sensitivity of the approach to variation and error in the initial and boundary conditions such as size and shape of the mandible, material properties of the bone tissue, muscle load vectors and the spatial constraints of the model. In the present paper we investigate the sensitivity of an FE model of a modern human mandible to simplifications in material properties and variations in boundary conditions. A medical CT scan of a living patient is used to create a range of FE digital models with different combinations of material properties, spatial constraints and muscle vectors. We then use ten individual CT scans of human mandibles to create simplified FE models all constrained and loaded in a standard way. We compare the development of von Mises strains over the surface of the mandibles, the output forces at the bite points and the modes and magnitudes global of deformations. Our results suggest that potential errors in segmentation, muscle force vectors, and constraints can have an appreciable effect on predictions of performance from FE analysis. Therefore, prediction of absolute strain magnitudes is uncertain. However, the errors are not large compared to the differences we find among the sample of mandibles, and FE analysis performs robustly in predicting relative, if not absolute, strains over the surface of a model. We suggest that a sensible approach in future comparative studies is to identically constrain and load ‘solid models’ comprising one homogenous material (e.g. with the properties of cortical bone). This limits studies to comparison of the effects of varying mandibular external form but such models reasonably predict relative strains, modes of global deformation and bite forces and so allow comparisons of these limited aspects of performance