Analysis of consolidation around driven piles in overconsolidated clay

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 161-169).The principal objective of this thesis is to assess the capabilities of an already established analytical framework for understanding and predicting the behavior of piles driven in highly overconsolidated clays (OCR24). The skin friction mobilized during pile loading to failure depends on the sequence of preceding events, i.e. pile installation and soil consolidation. This research utilizes the Strain Path Method (SPM) to simulate the disturbance caused by pile installation with a general effective stress soil model, MIT-Si, which is capable of modeling adequately the anisotropic stress-strain response of clays at large OCR. Following the pile installation, one-dimensional, non-linear, coupled consolidation analyses around the pile shaft are performed using the finite element code ABAQUS, simulating the earth and pore pressure equalization. The MIT-Si model has been integrated within the ABAQUS code. The MIT-SI model provides predictions of installation stresses that are generally consistent with prior work by using the MIT-E3 model. However, the research encountered several numerical problems during consolidation. Although some of these numerical issues have not been resolved, they do not appear to affect the current predictions of stresses at the pile shaft. The main contribution of this research is the extension of the capability offered by the aforementioned analytical framework to cover highly overconsolidated clays (OCR24). In general, the results show that the zone of disturbance in in terms of excess pore pressures around the pile generated by the MIT-SI model is much larger compared to MIT-E3 predictions. This discrepancy leads to different predictions between the two soil models particularly close to the pile shaft at the end of consolidation.by Dimitrios G. Niarchos.S.M

A DLT financial market infrastructure under the EU DLT Pilot Regime; a regulatory tug-of-war.

Ο ευρωπαϊκός νομοθέτης πρόσφατα εξέδωσε τον κανονισμό 2022/858 του Ευρωπαϊκού Κοινοβουλίου και του Συμβουλίου (DLTR), ο οποίος θεσπίζει το πιλοτικό καθεστώς για τις υποδομές της αγοράς που βασίζονται στην τεχνολογία κατανεμημένου καθολικού (TKK), και ειδικότερα σε ΠΜΔ-DLT ή ΚΑΤ-DLT, ή στην ενοποιημένη τους έκδοση, ως Σύστημα Διαπραγμάτευσης και Διακανονισμού DLT. Ο νέος κανονισμός τοποθετείται στην ατζέντα της ΕΕ για την προώθηση και την υιοθέτηση της ψηφιακής καινοτομίας, αν και με προσεκτική προσέγγιση λόγω των σχετικών κινδύνων. Ωστόσο, ορισμένες πτυχές της τεχνολογίας DLT που παρέχουν ευκαιρίες σημαντικής βελτίωσης της αποτελεσματικότητας της αγοράς, όπως η απο-διαμεσολάβηση και η ενοποίηση, μπορούν πλέον να εφαρμοστούν, μέσω ειδικών εξαιρέσεων από τους ισχύοντες κανόνες χάρη στις ρυθμίσεις του DLTR. Αυτή η καινοτόμος προσέγγιση του ευρωπαϊκού νομοθέτη της ΕΕ μοιάζει σε μεγάλο βαθμό με ένα «ρυθμιστικό (regulatory) sandbox», όπου οι συμμετέχοντες, τόσο οι εποπτικές αρχές όσο και οι παράγοντες της αγοράς, μπορούν να πειραματιστούν με την καινοτομία, προς όφελος ολόκληρης της χρηματοπιστωτικής αγοράς. Ωστόσο, η κίνηση αυτή συνοδεύεται, ταυτόχρονα, από εσωτερικούς περιορισμούς, οι οποίοι συνδέονται με τον βασικό στόχο της ΕΕ για διατήρηση της χρηματοπιστωτικής σταθερότητας. Σε τελική ανάλυση, ωστόσο, η πρωτοβουλία αυτή αποτελεί ένα βήμα προς τη σωστή κατεύθυνση, προς έναν φιλικότερο στην καινοτομία και ευέλικτο δημοσιονομικό κανονισμό της ΕΕ.The EU legislator has only recently adopted Regulation 2022/858 of the European Parliament and of the Council (DLTR), which introduces a Pilot Regime for market infrastructure based on DLT, more specifically a DLT-MTF or CSD, or in their consolidated version, as a DLT Trading and Settlement System. The new Regulation is inscribed in the EU agenda of promoting and adopting digital innovation, albeit with a cautious approach due to related risks. Nevertheless, certain aspects of DLT that provide opportunities of significant market efficiencies, such as disintermediation and consolidation, can now be implemented, through specific exemptions from standing rules, provided by DLTR. This innovative approach of the EU legislator heavily resembles a ‘regulatory sandbox’, where participants, both supervisors and market actors, can experiment with innovation, for the benefit of the whole financial market. However, this move is, at the same time, ridden with internal restrictions, linked to the EU’s longstanding objective of preserving financial stability. Ultimately, however, this initiative constitutes a step in the right direction, towards a more innovation-friendly and flexible EU Financial Regulation

Novel magnetic nanostructures: nanopillars and patterned antidots

Resumen del trabajo presentado en el Simposio Nuevas fronteras y retos en Magnetismo de la XXXVIII Reunión Bienal de la Real Sociedad Española de Física, celebrada en Murcia (España), del 11 al 15 de julio de 2022Two different nanostructures are studied in this contribution: large-area nanopillar arrays fabricated by glancing angle deposition with magnetron sputtering (MS-GLAD) and magnetic thin films perforated with long-range order arrays of nanoholes prepared by focused ion beam (patterned antidots). MS-GLAD is an easy and versatile route to fabricate arrays of nanostructures in large areas in a single processing step. In our work, nanostructured films with vertical or tilted nanopillars composed by polycrystalline Fe and Fe2O3 have been fabricated depending on whether the substrate is kept rotating azimuthally during deposition or not, respectively [1]. The magnetic properties of these films can be tuned with the specific morphology. In particular, the growth performed through a collimator mask mounted onto a not rotating azimuthally substrate produces almost isolated well-defined tilted nanopillars that exhibit a magnetic hardening. The first-order reversal curves diagrams and micromagnetic simulations revealed that a growth-induced uniaxial anisotropy, associated with an anisotropic surface morphology produced by the GLAD in the direction perpendicular to the atomic flux, plays an important role in the observed magnetic signatures. Magnetic antidots are being studied for different applications, such as magnonic crystals for microwave devices, magnetically-active plasmonic media, magnetic biosensing, and magneto-resistance sensors. In our work, a top-down approach using focused ion beam has been employed to fabricate Co/Permalloy hard-soft bilayer antidot arrays [2]. The antidots have a 40 nm diameter and two symmetries are studied: square and hexagonal. A dependence of magnetic coercivity on the relative thicknesses of the magnetically hard (Co) and soft (Permalloy) layers is found; increasing Permalloy thickness results in lower magnetic coercivity. Furthermore, the long-range periodicity of these antidots results in higher magnetic coercivity and a stronger magnetic domain-wall pinning, compared to identical hard/soft bilayers of short-range order deposited on porous anodic alumina. Finally, magnetic force microscopy (MFM) imaging of the antidot arrays shows striking qualitative differences between the two symmetries: square symmetry arrays have inhomogeneous magnetic state and a high density of immobile super-domain walls, whereas hexagonal symmetry arrays show a homogeneous magnetic configuration.The service from the MiNa Laboratory at IMN. Funding from MINECO, Comunidad de Madrid, European Union, Fondecyt, Dicyt-Usach, São Paulo Research Foundation, Brazilian National Council for S., NSRF Greece-EU, NATO

Magnetic properties of spinel-type oxides NiMn2-xMexO4

New materials, based on the well-known spinel compound NiMn2O4, have been synthesized and characterized from the magnetic point of view. The manganese cation was partially substituted in the general formula NiMn2-xMexO4 , by nonmagnetic and magnetic elements, such as Me = Ga, Zn, Ni and Cr (0 x 1). Prior to the determination of their magnetic properties, the non-substituted spinel NiMn2O4 was carefully characterized and studied as a function of the oxygen stoichiometry, based on the influence of the annealing atmosphere and quenching rate. The ferrimagnetic character was observed in all samples, with a paramagnetic-to-ferromagnetic transition temperature Tc stabilized at 110 K, and well defined long-range antiferromagnetic interactions at lower temperatures, which depend on the applied field and the substitute concentrationAuthors from Chile and O.P. thank projects Fondecyt-Chile 1020066, 7020066 and 1050178. Authors from France and Brazil thank project CAPES/COFECUB 416/03. Authors from France thank Région Bretagne for financial supportPeer reviewe

Gravity duals for the Coulomb branch of marginally deformed N=4 Yang-Mills

Supergravity backgrounds dual to a class of exactly marginal deformations of N supersymmetric Yang-Mills can be constructed through an SL(2,R) sequence of T-dualities and coordinate shifts. We apply this transformation to multicenter solutions and derive supergravity backgrounds describing the Coulomb branch of N=1 theories at strong 't Hooft coupling as marginal deformations of N=4 Yang-Mills. For concreteness we concentrate to cases with an SO(4)xSO(2) symmetry preserved by continuous distributions of D3-branes on a disc and on a three-dimensional spherical shell. We compute the expectation value of the Wilson loop operator and confirm the Coulombic behaviour of the heavy quark-antiquark potential in the conformal case. When the vev is turned on we find situations where a complete screening of the potential arises, as well as a confining regime where a linear or a logarithmic potential prevails depending on the ratio of the quark-antiquark separation to the typical vev scale. The spectra of massless excitations on these backgrounds are analyzed by turning the associated differential equations into Schrodinger problems. We find explicit solutions taking into account the entire tower of states related to the reduction of type-IIB supergravity to five dimensions, and hence we go beyond the s-wave approximation that has been considered before for the undeformed case. Arbitrary values of the deformation parameter give rise to the Heun differential equation and the related Inozemtsev integrable system, via a non-standard trigonometric limit as we explicitly demonstrate.Comment: 43 pages, Latex, 2 figures. v2: References added. v3: small typos corrected, published versio

Immunobiological study of the use of peptides and monoclonal antibodies in selective chemotherapy of cancer

In the present thesis, a 10-amino acid sequence, namely BagP, located within BAG-1 protein and which is rich in arginine and lysine residues was tested for its ability to act as a macromolecular carrier translocating cellular membranes. BagP was found to be a successful cell penetrating peptide (CPP), transferring high molecular weight cargo intracellularly in a vast range of cell types, albeit variably, with normal cells demonstrating a less permeable target for BagP, in contrast to the universal uptake of other peptides observed. The penetrating phenomenon of BagP was found to be both time- and concentration-dependent. In addition, the translocating ability of the peptide was found to be energy-reliant. Furthermore, the overall positive charge of BagP, as well as its initial interaction with heparin sulfate proteoglycans of the cellular membrane were found to be important parameters for its mechanism of translocation. The N-terminal of Bag-1 is known to play a key part in the protein’s anti-apoptotic role. Since BagP originates from the N-terminal of Bag-1, the peptide was tested for its ability to act antagonistically to several pathways that this terminal is known to be involved in. Hence, the antagonistic action of BagP in cells expressing Bag-1 would cause increased apoptosis. It was found that BagP at a concentration of 0,5 mM was able to induce increased apoptosis of the T cell lymphoma cell lines ALC (murine) and KARPAS-299 (human). The rest of the cell lines tested remained unaffected, whereas smaller BagP concentrations had no biological effect in all the cell lines tested. It is well documented that resting Natural Killer (NK) cells express the common β and γ subunits of interleukin (IL)-2 and IL-15 receptors, and that NK proliferation increases in the presence of IL-2 or IL-15, whilst IL-2 increases Bag-1 concentration. Therefore, it was tested whether incubation of resting NK cells with BagP would antagonize the increase of Bag-1 concentration due to the presence of IL-15. Similarly, only 0,5 mM of Bag-1 concentration was found to increase the percentage of apoptotic cells. Moreover, since Bag-1 inhibits the action of glucocorticoid receptor, if BagP would act as a Bag-1 antagonist, it would interrupt such an inhibition, leading to cellular death. Indeed, BagP at 0,5 mM, was found to lead to significant reduction of NK cell proliferation. Finally, we examined the ability of the BagP peptide to transfer intracellularly biologically active macromolecules. Initially, BagP was conjugated to an antisense oligonucleotide sequence (antimyc-aug) that is known to inhibit the expression of c-myc gene. The conjugate was found to be intracellularly transferred and to cause a reduction of the proliferation rate, without affecting cellular viability, while it was found to reduce the concentration of c-MYC protein. In addition, BagP was complexed to monoclonal antibody Trastuzumab (Herceptin). The purpose of this experimental approach was to check if the intracellular localization of the antibody in cells expressing the antibody’s targeting protein, HER2/neu, would prevent its expression on the cell membrane, thus reducing the cells’ ability to proliferate. The outcome of the experimental procedures was neither clear nor conclusive and further investigation is required.Στην παρούσα διατριβή μια αλληλουχία 10 αμινοξέων, πλούσια σε κατάλοιπα αργινίνης και λυσίνης, το πεπτίδιο BagP, που εντοπίζεται στην πρωτεΐνη BAG-1, εξετάστηκε για την ικανότητά του να λειτουργεί ως μακρομοριακός μεταφορέας ικανός να μεταφέρει το προσδεδεμένο του φορτίο διαμέσου κυτταρικών μεμβρανών. Το πεπτίδιο BagP βρέθηκε να δρα επιτυχώς ως κυτταροδιεισδυτικό πεπτίδιο (CPP), μεταφέροντας φορτία μεγάλου μοριακού βάρους ενδοκυτταρικά σε μεγάλο εύρος κυτταρικών τύπων. Σε αντίθεση όμως με τα μέχρι σήμερα γνωστά CPP, το BagP μετατοπίζεται σε διαφορετικό βαθμό στο εσωτερικό διαφόρων κυττάρων. Η μετατοπιστική αυτή ικανότητα του BagP εξαρτάται τόσο από τη διάρκεια της επώασης, όσο και από τη συγκέντρωση του πεπτιδίου. Επιπλέον φαίνεται ότι η διείσδυση του BagP γίνεται μέσω ενός ενεργειακά εξαρτώμενου μοντέλου. Φαίνεται ακόμα ότι το συνολικό θετικό φορτίο του BagP καθώς και η πρόσδεσή του στις θειικές ηπαρανικές πρωτεογλυκάνες της κυτταρικής μεμβράνης είναι σημαντικές παράμετροι για την ενδοκυτταρική του μετατόπιση. Δεδομένης της προέλευσης του πεπτιδίου BagP από το αμινοτελικό άκρο της πρωτεΐνης BAG-1, το πεπτίδιο εξετάστηκε για την πιθανή ανταγωνιστική του δράση σε αρκετά σηματοδοτικά μονοπάτια στα οποία συμμετέχει το αμινοτελικό άκρο της BAG-1. Η τυχόν ανταγωνιστική δράση του πεπτιδίου BagP θα προκαλούσε αυξημένα ποσοστά απόπτωσης στα κύτταρα που εκφράζουν την πρωτεΐνη BAG-1. Διαπιστώθηκε ότι συγκέντρωση του BagP της τάξης του 0,5 mM είναι ικανή να επάγει αυξημένα ποσοστά απόπτωσης στις κυτταρικές σειρές T-λεμφώματος ALC (ποντικού) και KARPAS-299 (ανθρώπου). Άλλες κυτταρικές σειρές δεν βρέθηκαν να επηρεάζονται, ενώ μικρότερες συγκεντρώσεις του πεπτιδίου δεν έδειξαν ανιχνεύσιμη βιολογική επίδραση ούτε στις δύο αυτές κυτταρικές σειρές. Είναι γνωστό ότι τα μη ενεργοποιημένα φυσικά φονικά (ΝΚ) κύτταρα εκφράζουν τις κοινές για τις κυτταροκίνες ιντερλευκίνη (IL)-2 και IL-15, β και γ υπομονάδες των υποδοχέων τους και ότι ο πολλαπλασιασμός τους αυξάνεται παρουσία IL-2 ή IL-15, ενώ η IL-2 προκαλεί επιπλέον αύξηση της συγκέντρωσης της πρωτεΐνης BAG-1. Συνεπώς, μελετήθηκε αν η επώαση μη ενεργοποιημένων NK κυττάρων με το BagP θα ανταγωνιζόταν την αύξηση της BAG-1 λόγω της παρουσίας IL-15. Και σε αυτή την περίπτωση, μόνο συγκέντρωση του BagP της τάξης του 0,5 mM βρέθηκε να αυξάνει τα ποσοστά απόπτωσης των κυττάρων αυτών. Επιπρόσθετα, καθώς η BAG-1 αναστέλλει τη δράση του υποδοχέα γλυκοκορτικοειδών, μελετήθηκε αν το BagP, ως ανταγωνιστής της πρωτεΐνης, θα ανέκοπτε την αναστολή των υποδοχέων αυτών, προκαλώντας κυτταρικό θάνατο. Πράγματι, σε συγκέντρωση 0,5 mM BagP παρατηρήθηκε έντονη μείωση του πολλαπλασιασμού των ΝΚ κυττάρων. Τέλος, μελετήθηκε η ικανότητα του BagP να μεταφέρει ενδοκυτταρικά βιολογικά ενεργά μακρομόρια. Αρχικά στο BagP συζεύχθηκε αντινοηματική αλληλουχία ολιγονουκλεοτιδίου (antimyc-aug) που αναστέλλει την έκφραση του c-myc γονιδίου. Το σύζευγμα αυτό διαπιστώθηκε να μεταφέρεται ενδοκυτταρικά και να προκαλεί μείωση του πολλαπλασιασμού, αφήνοντας ανεπηρέαστη για το αντίστοιχο χρονικό διάστημα την κυτταρική βιωσιμότητα, ενώ παράλληλα βρέθηκε να μειώνει και τη συγκέντρωση της πρωτεΐνης c-MYC

NATO Advanced Training Course on Spintronics Radar Detectors

Magnetic and spintronic materials are ubiquitous in modern technological applications, e.g. in electric motors, power generators, sensors and actuators, not to mention information storage and processing. Medical technology has also greatly benefited from magnetic materials – especially magnetic nanoparticles – for therapy and diagnostics methods. All of the above-mentioned applications rely on the properties of the materials used. These properties in turn depend on intrinsic and extrinsic material parameters. The former are related to the actual elements used and their properties, e.g. atomic magnetic moment and exchange interaction between atoms; the latter are related to the structural and microstructural properties of the materials used, e.g. their crystal structure, grain size, and grain boundary phases. Focusing on state-of-the-art magnetic and spintronic materials, this book will introduce readers to a range of related topics in Physics and Materials Science. Phenomena and processes at the nanoscale

Structural and magnetic properties of L10 FePt/Interlayer/L10 FePt trilayers

Trabajo presentado en el 8th Joint European Magnetic Symposia JEMS, celebrado en Glasgow (Reino Unido), del 21 al 26 de agosto de 2016Peer reviewe