282 research outputs found
Data Set of PLOS Computational Paper PCOMPBIOL-D-18-02181R1
No full textFigures Data of PLOS Computational paper:Modeling of the axon plasma membrane structure and its effects on protein diffusionAuthors: Yihao Zhang, Anastasios V. Tzingounis, and George LykotrafitisCorresponding Author: George Lykotrafitis, Ph.D.University of ConnecticutStorss, CT UNITED STATES</div
The state of modern Greek language as spoken in Victoria
No full textDeposited with permission of the author. © 1986 Dr. Anastasios TamisThis thesis reports a sociolinguistic study, carried out between 1981 and 1984, of the state of the Modern Greek (MG) language in Australia, as spoken by native-speaking first-generation Greek immigrants in Victoria. Particular emphasis is given to the analysis of those characteristics of the linguistic behaviour of these Greek Australians which can be attributed to the contact with English and to other environmental, social and linguistic influence. (For complete abstract open document
New historical evidence for Anastasios Emm. Papas
No full textNo AbstractThe author’s attention has been drawn to the existence of this historicalevidence in the National Archives of Vienna, by his friend the writer EteoclesGregoriadis together with the numbers of the relevant files. Most of the documents were written in the old German script. Thus the author asked for the help of his friend and former colleague at the University of Thessaloniki and director of the Goethe Institute, Graf Kurt v. Posadowsky, for reading andstudying those documents. Without his help this study would have been impossible. This new evidence concerns the sojourn of Anastasios Papas·—son of Emmanuel Papas, leading figure of the Greek Revolution—in Austria andGermany between the 3rd January and 11th March 1822. There is informationabout his short imprisonment in Trieste, after his arival from Vienna. He then visits various towns in Germany and after negotiations with the Philhellene professor Fr. Thiersch in Munich, he purchases large quantities of ammunition to be despatched to Greece. He finally arrives in Greece early in 1824, and takes part—together with his three brothers who were already fighting—in the struggle for the liberation of the common great fartheland
Dynamic system for modeling and computing the propagation of continuous and pulsed radiation in scattering media of arbitrary 3D geometry
No full textA new dynamic-system approach is presented in this thesis to the problem of radiative transfer within media that exhibit both scattering and absorption properties. This methodology is fundamentally grounded in first hand physical principles. This method, denoted as Dynamic Radiative Transfer System (DRTS), employs a dynamical system formalism to model the radiative transfer. Central to this methodology is the construction and use of a global sparse matrix. This matrix is designed to encapsulate and represent the various physical, optical, and geometrical characteristics that define the specific material-volume being analyzed. In this system, the creation of a new state is generated by this system time-independent matrix, using simple matrix-vector multiplication for each subsequent time step. One of the notable features of DRTS is its ability to compute with high accuracy the temporal evolution of photon propagation within media that are structurally complex and varied in shape. The flexibility of the DRTS is further evidenced by its capacity to seamlessly integrate multiple elements. These include time-dependent sources, various boundary conditions, diverse types of media and several optical phenomena like reflection and refraction, which are embedded in a unified and consistent way. Various examples of DRTS simulation results are presented ranging from the continuous down to the ultra-fast light pulse 3-D propagation. The results from these simulations are particularly noteworthy for significantly reduced computational demands and resource requirements, especially when compared with other existing methods in the field. By further applying simple intensity-normalization processing, clean images of the embedded objects can be extracted. The pulse evolution through the medium can be traced and displayed in time-frame sequence, depicting the gradual image formation and fading. Also, it is demonstrated that illumination from scattered photons in the medium is advantageous, yielding clean full-frame images, eliminating the need for traditional beam scanning techniques. Additionally, image retrieval is significantly enhanced by capturing photons that are directionally selected, thereby revealing three-dimensional objects that are embedded deeper within the medium. In contrast with the accepted notion that early photons are the only means for image formation, DRTS proves that there exists a capability for image formation using the scattered photons. The forward-problem simulation results have broad-ranging implications and potential applications across various scientific and technological domains.Στην παρούσα διατριβή παρουσιάζεται μια νέα προσέγγιση χρησιμοποιώντας ένα δυναμικό σύστημα για το πρόβλημα της μεταφοράς ακτινοβολίας εντός μέσων με ιδιότητες έντονης σκέδασης και απορρόφησης. Αυτή η μεθοδολογία βασίζεται σε πρωταρχικές αρχές της φυσικής. Η μέθοδος αυτή, εν ονόματι Δυναμικό Σύστημα Μεταφοράς Ακτινοβολίας (Dynamic Radiative Transfer System, DRTS), ενσωματώνει την έννοια του δυναμικού συστήματος για τη μοντελοποίηση της μεταφοράς ακτινοβολίας. Για την υλοποίηση της συγκεκριμένης μεθοδολογίας κατασκευάστηκε ένας γενικός αραιός πίνακας, ο οποίος σχεδιάστηκε για να ενσωματώνει και να αντιπροσωπεύει τις διάφορες φυσικές, οπτικές και γεωμετρικές ιδιότητες που καθορίζουν τον συγκεκριμένο όγκο υλικού που αναλύεται. Σε αυτό το σύστημα, κάθε νέα κατάσταση (state) παράγεται από αυτόν τον πίνακα του συστήματος που είναι ανεξάρτητος του χρόνου, χρησιμοποιώντας πολλαπλασιασμούς πίνακα-διανύσματος, για κάθε επόμενο βήμα χρόνου. Βασικό πλεονέκτημα της DRTS είναι η ικανότητά της να υπολογίζει με υψηλή ακρίβεια την χρονική εξέλιξη της διάδοσης φωτονίων εντός μέσων που χαρακτηρίζονται από δομική πολυπλοκότητα και ποικίλα σε σχήμα. Επιπροσθέτως, αποδεικνύεται ως μία ευέλικτη μέθοδος καθώς μπορεί να ενσωματώνει πολλαπλά στοιχεία. Σε αυτά περιλαμβάνονται πηγές εξαρτώμενες από το χρόνο, διάφορες συνοριακές συνθήκες, διαφορετικές μορφές μέσων και διάφορα οπτικά φαινόμενα όπως η ανάκλαση και η διάθλαση, στοιχεία που εντάσσονται με ενιαίο και συνεκτικό τρόπο. Παρουσιάζονται διάφορα παραδείγματα αποτελεσμάτων προσομοιώσεων της DRTS που κυμαίνονται από συνεχή έως υπερ-ταχείας διάδοση παλμού φωτός στον τρισδιάστατο χώρο. Στα αποτελέσματα αναδεικνύεται η μειωμένη ανάγκη υπολογιστικών πόρων, συγκριτικά με άλλες υπάρχουσες μεθόδους. Με την περαιτέρω εφαρμογή απλής επεξεργασίας της κανονικοποιημένης έντασης, μπορούν να παραχθούν καθαρές εικόνες των εσωτερικών αντικειμένων. Η εξέλιξη του παλμικού σήματος μέσα στο μέσο προσομοιώνεται και απεικονίζεται με τη μορφή ακολουθίας στιγμιότυπων εικόνων, παρουσιάζοντας τη σταδιακή δημιουργία και εξασθένιση της εικόνας των όγκων. Επιπλέον, αποδεικνύεται ότι υπάρχουν σημαντικά πλεονεκτήματα από τον φωτισμό του μέσου από σκεδαζόμενα φωτόνια, αφού παρουσιάζονται καθαρές πλήρεις εικόνες, εξαλείφοντας την ανάγκη για παραδοσιακές τεχνικές σάρωσης του όγκου. Επιπλέον, η ανάκτηση εικόνας ενισχύεται σημαντικά με την καταγραφή φωτονίων που επιλέγονται με βάση συγκεκριμένες κατευθύνσεις, αποκαλύπτοντας τρισδιάστατα αντικείμενα που είναι βαθύτερα μέσα στο μέσο. Σε αντίθεση με την επικρατούσα αντίληψη ότι τα πρώιμα φωτόνια είναι η μόνη μέθοδος για τη δημιουργία εικόνας, η DRTS αποδεικνύει ότι υπάρχει δυνατότητα δημιουργίας εικόνας χρησιμοποιώντας τα σκεδαζόμενα φωτόνια. Τα αποτελέσματα των προσομοιώσεων για το ευθύ πρόβλημα της σκέδασης έχουν ευρύτατες συνέπειες και πιθανές εφαρμογές σε διάφορους επιστημονικούς και τεχνολογικούς τομείς
GLUCOCORTICOID RECEPTOR SYNERGISM WITH TRANSCRIPTION FACTORS IN RECEPTOR - REGULATED GENE EXPRESSION
No full textGLUCOCORTICOID HORMONES AND INSULIN REGULATE GENE EXPRESSION IN A COOPERATIVE MANNER. WE SHOW THAT IN RAT HEPATIC CELLS INSULIN ENHANCES SYNERGISTICALLY THEGLUCOCOTRICOID INDUCED EXPRESSION OF CAT. THE PRESENCE OF ACTIVE GLUCOCORTICOID RESPONSE ELEMENTS (GRES) ON CAT PROMOTER IS REQUIRED AND THE INDUCTION DEPENDS ON THE INSULIN CONCENTRATION AND ON THE PRESENCE OF ACTIVE GLUCOCORTICOID RECEPTOR (GR). INSULIN ALTERS NEITHER THE AFFINITY OF GR FOR ITS HORMONE NOR ITS AFFINITY FOR THE DNA. INSULIN ACTS IN A SEQUENCE SPECIFIC MANNER AND AT THE TRANSCRIPTIONAL LEVEL. IT DOES NOT ACT AT THE POST - TRANSCRIPTIONAL OR THEPOST - TRASLATIONAL LEVEL. WE ALSO SHOW THAT IN HUMAN HEPATOMA CELLS A SINGLE COPY OF A GRE ON CAT PROMOTER CAN MEDIATE THE INSULIN ENHANCEMENT OF GLUCOCORTICOID INDUCED CAT EXPRESSION. THE N' - TERMINAL AND THE C' - TERMINAL DOMAINS OF GR ARE NOT INVOLVED IN MEDIATING THE RESPONSE. INSULIN HAD NO EFFECT ONGR BINDING TO GRE AND IT DIDN'T CAUSE THE INTERACTION OF ANY OTHER TRANSCRIPTION FACTOR WITH THE GR ON THE GRE. FINALLY WE SHOW THAT INSULIN AFFECTS BOTH THE NUCLEAR LEVELS AND THE PHOSPHORYLATION STATE OF GR. THE COMBINATORIAL ACTION OF BOTH HORMONES KEEP NUCLEAR GR AT LOW LEVELS WHILE AT THE SAME TIME IT INDUCES THE PHOSPHORYLATION OF NUCLEAR GR. THE PHOSPHORYLATION IS AT SERINE/THEONINE RESIDUES SINCE AT THE SAME TIME WE OBSERVE A DRAMATIC DEPHOSPHORYLATIONAT TYROSINE RESIDUES. THE (ABSTRACT TRUNCATED)ΣΤΗΝ ΠΑΡΟΥΣΑ ΕΡΓΑΣΙΑ ΔΕΙΧΝΕΤΑΙ ΠΩΣ ΟΙ ΓΛΥΚΟΚΟΡΤΙΚΟΕΙΔΕΙΣ ΟΡΜΟΝΕΣ ΚΑΙ Η ΙΝΣΟΥΛΙΝΗ ΡΥΘΜΙΖΟΥΝ ΤΗ ΓΟΝΑΔΙΑΚΗ ΕΚΦΡΑΣΗ ΚΑΤΑ ΤΡΟΠΟ ΣΥΝΕΡΓΙΣΤΙΚΟ. ΠΑΡΑΤΗΡΟΥΜΕ ΠΩΣ ΣΕΚΥΤΤΑΡΑ ΗΠΑΤΟΣ ΑΡΟΥΡΑΙΟΥ Η ΙΝΣΟΥΛΙΝΗ ΑΥΞΑΝΕΙ ΣΥΝΕΡΓΙΣΤΙΚΑ ΜΕ ΤΗ ΔΕΞΑΜΕΘΑΖΟΝΗΤΗΝ ΕΚΦΡΑΣΗ ΤΟΥ ΓΟΝΙΔΙΟΥ ΤΗΣ ΑΚΕΤΥΛΟΤΡΑΝΣΦΕΡΑΣΗΣ ΤΗΣ ΧΛΩΡΑΜΦΑΙΝΙΚΟΛΗΣ (CAT).ΤΟ ΦΑΙΝΟΜΕΝΟ ΑΥΤΟ ΑΠΑΙΤΕΙ ΤΗΝ ΥΠΑΡΞΗ ΣΤΟΙΧΕΙΩΝ ΑΠΟΚΡΙΝΟΜΕΝΩΝ ΣΤΑ ΓΛΥΚΟΚΟΡΤΙΚΟΕΙΔΗ (GLUCOCORTICOID RESPONSE ELEMENT, GRE) ΣΤΟΝ ΥΠΟΚΙΝΗΤΗ ΤΗΣ CAT ΚΑΙ ΕΞΑΡΤΑΤΑΙ ΑΠΟ ΤΗ ΣΥΓΚΕΝΤΡΩΣΗ ΤΗΣ ΙΝΣΟΥΛΙΝΗΣ ΚΑΙ ΤΗΝ ΠΑΡΟΥΣΙΑ ΕΝΕΡΓΟΥ ΥΠΟΔΟΧΕΑ ΓΛΥΚΟΚΟΡΤΙΚΟΕΙΔΩΝ (GLUCOCORTICOID RECEPTOR, GR). Η ΙΝΣΟΥΛΙΝΗ ΔΕΝ ΕΠΙΔΡΑ ΣΤΗ ΣΥΓΓΕΝΕΙΑ ΤΟΥ GR ΓΙΑ ΤΗ ΔΕΞΑΜΕΘΑΖΟΝΗ ΟΥΤΕ ΣΤΗ ΣΥΓΓΕΝΕΙΑ ΤΟΥ GR ΓΙΑ ΤΟ DNA. Η ΡΥΘΜΙΣΗ ΤΗΣ ΕΚΦΡΑΣΗΣ ΤΗΣ CAT ΓΙΝΕΤΑΙ ΣΤΟ ΕΠΙΠΕΔΟ ΤΗΣ ΜΕΤΑΓΡΑΦΗΣ ΚΑΙ ΟΧΙ ΜΕΤΑ - ΜΕΤΑΓΡΑΦΙΚΑ Η ΜΕΤΑ - ΜΕΤΑΦΡΑΣΤΙΚΑ. ΕΝΑ ΚΑΙ ΜΟΝΟ ΣΤΟΙΧΕΙΟ ΑΠΟΚΡΙΣΗΣ ΣΤΑ ΓΛΥΚΟΚΟΡΤΙΚΟΕΙΔΗ (GRE) ΣΤΟΝ ΥΠΟΚΙΝΗΤΗ ΤΗΣ CAT ΕΙΝΑΙ ΙΚΑΝΟ ΚΑΙ ΑΝΑΓΚΑΙΟ ΓΙΑ ΤΗΝ ΣΥΝΕΡΓΙΣΤΙΚΗ ΑΥΞΗΣΗ ΤΗΣ ΕΚΦΡΑΣΗΣ ΤΗΣ CAT ΑΠΟ ΤΙΣ ΔΥΟ ΟΡΜΟΝΕΣ. ΕΠΙΣΗΣ ΣΤΟ ΣΥΝΕΡΓΙΣΜΟ ΔΕ ΣΥΜΜΕΤΕΧΟΥΝ ΤΟ ΑΜΙΝΟΤΕΛΙΚΟ ΚΑΙ ΤΟ ΚΑΡΒΟΞΥΤΕΛΙΚΟ ΤΜΗΜΑ ΤΟΥ ΜΟΡΙΟΥ GR. Η ΙΝΣΟΥΛΙΝΗ ΔΕΝ ΕΠΑΓΕΙ ΤΗΝ ΑΛΛΗΛΕΠΙΔΡΑΣΗ ΚΑΠΟΙΟΥ ΠΑΡΑΓΟΝΤΑ ΜΕ ΤΟΝ GR ΚΑΤΑ ΤΗ ΣΥΝΔΕΣΗ ΤΟΥΜΕ ΤΟ GRE, ΟΥΤΕ ΜΕΤΑΒΑΛΛΕΙ ΤΗ ΣΤΑΘΕΡΟΤΗΤΑ ΜΕ ΤΗΝ ΟΠΟΙΑ Ο GR ΣΥΝΔΕΕΤΑΙ ΣΤΟ GRE. ΤΕΛΟΣ ΠΑΡΑΤΗΡΟΥΜΕ ΠΩΣ Η ΣΥΝΔΥΑΣΜΕΝΗ ΔΡΑΣΗ ΤΩΝ ΔΥΟ ΟΡΜΟΝΩΝ ΚΡΑΤΑ ΜΕΓΑΛΟ ΜΕΡΟΣ ΤΟΥ GR ΕΞΩ ΑΠΟ ΤΟΝ ΠΥΡΗΝΑ, ΠΡΟΚΑΛΩΝΤΑΣ ΥΠΕΡΦΩΣΦΟΡΥΛΙΩΣΗ ΤΩΝ ΧΑΜΗΛΩΝ ΕΠΙΠΕΔΩΝΠΥΡΗΝΙΚΟΥ GR. ΤΑΥΤΟΧΡΟΝΑ ΠΡΟΚΑΛΕΙΤΑΙ ΑΠΟΦΩΣΦΟΡΥΛΙΩΣΗ ΚΑΤΑΛΟΙΠΩΝ ΤΥΡΟΣΙΝΗΣ, ΠΟΥ ΦΑΙΝΕΤΑΙ ΝΑ ΠΑΙΖΕΙ ΛΕΙΤΟΥΡΓΙΚΟ ΡΟΛΟ ΣΤΗΝ ΕΜΦΑΝΙΣΗ ΤΟΥ ΣΥΝΕΡΓΙΣΜΟΥ
Measurement of damage growth in ultrasonic spot welded joint
No full textUltrasonic spot welding is a joining technique for thermoplastic composites with great potential regarding processing speed and cost. To investigate the damage tolerance and possible inherent damage arresting behavior of multi-spot welded joints, a technique is necessary to measure damage growth in the joints under cyclic loading. Visual inspection is not possible because the damage is not located on the outside surface and conventional techniques such as C-scan are not practical during a fatigue test because the specimen would have to be removed from the setup. This paper details a methodology for quantifying damage growth rates in singlespot welded joints using surface strain measurements made by Digital Image Correlation. This represents the first step towards developing a methodology for quantifying damage progression behavior in complex multi-spot welded joints.Structural Integrity & CompositesAerospace Structures & Computational Mechanic
Development and characterization of hybrid thin-ply composite materials
No full textThin-ply composites are recognized as a key solution for the manufacturing of high-performance composite structures due to the unique mechanical properties and the increased design versatility that they offer. They are obtained with state-of-the-art fiber spreading methods where high-count (6-24K filaments) tows of technical fibers (carbon, glass) are thinned by spreading into flat unidirectional tapes which are then combined with a polymer matrix to create pre-impregnated (prepregs) tapes of reduced thickness. In recent years, the industrialization of fiber spreading and impregnation processes enabled the large-scale production of homogenous thin-ply prepregs with thicknesses down to about 15μm per ply, which attracted the interest of the research community. However, the high production cost due to the complexity of the manufacturing methods and the inherent brittleness of thin-ply composites limit their wider adoption by the composites industry[1]. Fiber hybridization (i.e combining at least two types of fibers in a common matrix) is emerging as a promising approach for alleviating these drawbacks towards laminates with balanced characteristics in terms of mechanical properties and cost-efficiency. Currently, most studies on thin-ply hybrids employ simple interlayer (ply-by-ply) configurations mainly due to difficulties in manufacturing of more complex hybrid architectures[2]. However, simulation tools predict that notable improvements can be obtained from more complex intralayer (tow-by-tow) and intrayarn (fiber-by-fiber) hybrid architectures[3]. This work focuses on the study of existing fiber spreading methodologies, the development of equipment, and the optimization of composite processing at North Thin Ply Technology (NTPT) Renens, Switzerland, that allowed the manufacturing of hybrid composites with a high degree of fiber dispersion and controlled microstructure. Hybrid prepregs were produced by combining various ratios of dissimilar fibers following different processing routes. Composite laminates were manufactured and a versatile microstructural analysis tool was developed that enabled correlations between the manufacturing route, the resulting microstructural features describing the degree of co-dispersion, and the mechanical performance of the final part. Acknowledgments The research leading to these results has been performed within the framework of the HyFiSyn project and has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 765881. Delamination growth in fibre reinforced polymer composites is generally evaluated with experiments that have been standardized for quasi-static load conditions. These tests characterize unidirectional delamination growth in mode I (DCB), mode II (ELS or ENF) of mixed mode conditions (MMB). However, little attention is paid in literature to the applicability of these tests to in-service delamination problems that are generally characterized by planar delamination growth. In this study, the relation between planar delamination growth, induced by transverse quasi-static indentation loading, and these unidirectional delamination tests was investigated. To that aim, prior planar delamination growth tests reported in literature, performed at EPFL, were analysed to identify up to what extent this planar growth could be correlated to the concepts of strain energy release and strain energy density. Once this appeared to successful, an experimental setup was designed to measure the delamination boundary during the transverse indentation loading of planar delamination specimens made of nontransparent carbon fibre reinforced polymer composites. With that set-up, quasi-static and fatigue planar delamination growth experiments were performed, and delamination contours could be successfully captured. While the quasi-static tests revealed limited growth, evaluation with numerical simulations revealed that the indentation force required to extend the delamination quasi-statically would cause damage to the specimen. This is attributed to the increasing length of the delamination contour when delaminations expand, which is not the case with standard unidirectional specimen. With the fatigue tests, however, delamination growth was achieved, but interestingly enough two phases were observed; first the delamination propagated in a planar fashion, while at some point in time work did not exceed an apparent threshold. Instead of no growth, however, the delamination still increased but then in a transverse manner. What makes this study of particular interest, is that the strain energy density as criterion could capture the strain energy offered (work) along the entire delamination contour, while the strain energy release rate described the resistance to delamination growth. This latter observation is in agreement with the original concept employed by Griffith when he formulated the basis of linear elastic fracture mechanics. This presentation present the experiments performed, the analysis of results, and will conclude with a proposal how to relate standard unidirectional tests to planar growth, considering that these standard tests contain little to no information on transverse phenomena with respect to strain energy density (work) and strain energy release (dissipation).Aerospace Manufacturing Technologie
The role of matrix boundary in the microstructure of unidirectional composites
No full textFinding new ways to evaluate the variability of microstructures, and its effect on macroscopic properties such as permeability and mechanical performance [1,2] is of increasing interest in the composite field. The variability of microstructural features at a three-dimensional level is not fully understood and its effect on macroscale properties is not well established, and mostly analyzed at a phenomenological level [3]. We introduced in recent work a method based on X-ray Computed Tomography for the threedimensional reconstruction of the fibrous microstructure of unidirectional tapes at a single fibre resolution [4]. A schematic of the workflow is represented in Figure 1. Three descriptors are introduced in the work to describe increasing level of complexity in the microstructural organization, from a single fiber path level with differential tortuosity, to group behavior with collective motion, to fibre network connectivity with length of contact. These descriptors and their interdependence highlight local effects like edge-core segregation in microstructural characteristics. However, in order to achieve a more complete definition of the unidirectional tape domain, understanding of matrix-based features and its interrelation with fiber architecture descriptors is needed. In this work, we expand the methodology of Gomarasca et al. [4], to account for matrix-based phenomena such as tape boundary variability, and void formation and morphology. This will be showcased on a unidirectional composite tape including both fiber-based and matrix-based analysis. These methods enable advanced characterization and modelling of microstructural formation and evolution during composite manufacturing.Aerospace Manufacturing TechnologiesAerospace Structures & Computational Mechanic
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