Numerical Analysis of the Reuse of Piled Raft Foundations

This thesis considers the reuse and the optimum design of piled raft foundations using numerical analysis. The solution proposed for reusing foundations is the design of a piled raft foundation capable of supporting successive buildings. A raft foundation, with a limited number of piles located strategically beneath the raft and utilising a high proportion of the ultimate load capacity, is considered the most efficient design when the raft foundation alone provides sufficient load capacity, but at the same time settlements are excessive. This is the case in high plasticity stiff clays such as London Clay. When building on old piles, these piles had to sustain a certain load from the previous structure over a period of time, during which the soil is subjected to the time-related processes of consolidation and creep. A time dependent constitutive model, capable of reproducing several aspects of the time dependent behaviour of soils including creep and isotach viscosity, is employed in the finite element analyses. The model parameters are calibrated with the results of laboratory tests on London Clay, whose time dependent behaviour in its natural state is characterised by isotach viscosity, rate dependent peak strength and rate independent critical state line. Preliminary analyses of single piles indicate that the consolidation processes in the ground result in little gain in capacity in the long term, whereas creep results in increased capacity. A back-analysis of documented piled load tests in London Clay is performed, where the effects of pile installation are quantified. Numerical model calibration is performed with the documented observations of a well instrumented piled raft foundation at Stonebridge Park, London. 3D parametric analyses of piled raft foundations are then performed, in order to assess the appropriate location and dimensions of piles and raft thickness. The performance of piled raft foundations with time is assessed parametrically at different levels of preloading. Optimisation of the performance of the piled raft foundation at Stonebridge Park is attempted by examining several pile arrangements, where a central pile support with a limited number of piles is more cost-effective than the original design

Forecasting the Oil Volatility Index Using Factors of Uncertainty

The oil volatility index (OVX) has attracted the attention of investors, as oil prices have been subject to high degrees of variation in the last few decades, and investors would therefore benefit from obtaining accurate forecasts of OVX. In this paper, we aim to develop models that can accurately generate OVX forecasts. The contribution of our study to the literature lies in the incorporation of different factors that reflect uncertainty as potential drivers of OVX. For example, implied volatility (IV) indices, such as the VIX and GVZ are examined. Apart from the inclusion of IV indices, we investigate whether other uncertainty indicators play a significant role in generating OVX forecasts. Our results show that the predictive ability of the models is not enhanced by the inclusion of most of the aforementioned factors of uncertainty, with the single exception of the U.S. economic policy uncertainty index, which seems to improve the forecasting ability of a simple model that focuses on the OVX as a target variable

Ανάπτυξη Συστημάτων Διαδερμικής Χορήγησης Φαρμακολογικά Δραστικών Ουσιών με Ασθενώς Βασικό Χαρακτήρα

Η διαδερμική χορήγηση φαρμακολογικά δραστικών ουσιών (ΦΔΟ), εάν είναι δυνατόν να επιτευχθεί, παρουσιάζει σημαντικά πλεονεκτήματα σε σύγκριση με τις συμβατικές οδούς χορήγησης, δηλαδή την από του στόματος και την ενδοφλέβια οδό, όπως αποφυγή του φαινομένου πρώτης διόδου, επίτευξη σταθερών επιπέδων στο πλάσμα και βελτίωση της συμμόρφωσης των ασθενών. Σκοπός λοιπόν της παρούσας μελέτης ήταν η in vitro αξιολόγηση της διαπερατότητας ΦΔΟ με ασθενώς βασικό χαρακτήρα, δραστική ουσία Α και δραστική ουσία Β, μέσω της επιδερμίδας ως πρώτο βήμα για την ανάπτυξη διαδερμικών θεραπευτικών συστημάτων (ΔΘΣ) με επιθυμητό ρυθμό αποδέσμευσης. Στο πλαίσιο αυτό μελετήθηκε η επίδραση ορισμένων παραγόντων, όπως η χημική μορφή των ΦΔΟ, η σύσταση του φορέα διαδερμικής χορήγησης καθώς και το δέρμα από διαφορετικούς δότες. Για τα in vitro πειράματα διαδερμικής διαπερατότητας χρησιμοποιήθηκαν τροποποιημένα, κάθετα κύτταρα διάχυσης τύπου Franz και ανθρώπινη επιδερμίδα από δέρμα διαφορετικών δοτών, θηλυκού φύλου. Οι συνθέσεις που περιείχαν τη δραστική ουσία Α με τη μορφή υδροχλωρικού άλατος (A-HCl) εμφάνισαν εξαιρετικά χαμηλές τιμές Q, ποσότητα δηλαδή της A-HCl που διαπερνούσε την επιδερμίδα ανά μονάδα επιφανείας σε μονάδες μg/cm2, στις 12, 24, 36 και 48 h από την έναρξη του πειράματος. Ούτε ο διαφορετικός οργανικός διαλύτης της σύνθεσης αλλά ούτε και το δέρμα από διαφορετικό δότη επηρέασαν στατιστικά σημαντικά την απορρόφησή της, με συνέπεια η ροή να χαρακτηρίζεται σε κάθε περίπτωση ανεπαρκής. Οι συνθέσεις που περιείχαν τη δραστική ουσία Α με τη μορφή ασθενούς βάσης εμφάνισαν μεγαλύτερες τιμές Q σε όλες τις χρονικές στιγμές δειγματοληψίας, επιτυγχάνοντας θεραπευτικά επίπεδα για περισσότερο από 48 h ύστερα από χορήγηση ΔΘΣ τύπου δεξαμενής με μέγεθος μικρότερο από 12 cm2. Όσον αφορά τα ΔΘΣ τύπου Drug-in-Adhesive (DIA), η κλασική μέθοδος (monolithic patches) δεν ήταν λειτουργική εξαιτίας της πτητικότητας της ΦΔΟ σε θερμοκρασίες μεγαλύτερες από 35ºC για αυτό και δοκιμάστηκε η τεχνική multilaminate – sandwich patches. Ωστόσο, παρόλο που το αρχικό πρόβλημα αντιμετωπίστηκε, παρατηρούνταν μεγάλη απόκλιση στη συγκέντρωση της δραστικής ουσίας Α από τη θεωρητική γεγονός που πιθανότατα οφείλεται είτε στη μεμβράνη υποστήριξης (backing membrane) είτε στο πιεσοευαίσθητο συγκολλητικό (pressure sensitive adhesive – PSA). Τέλος, σχετικά με τις συνθέσεις που περιείχαν την ασθενή βάση της δραστικής ουσίας Β, δεν εμφάνισαν επαρκείς τιμές Q ώστε να επιτυγχάνονται θεραπευτικά επίπεδα στο πλάσμα από ΔΘΣ αποδεκτού εμβαδού. Επιπλέον, η αυξανόμενη περιεκτικότητα σε αιθανόλη και η αντίστοιχη μεταβολή της συγκέντρωσης της ΦΔΟ δεν εμφάνισαν ανάλογα αποτέλεσμα στη ροή μέσω του δέρματος. Συμπεραίνεται λοιπόν πως τα επίπεδα των ΦΔΟ στο πλάσμα ύστερα από διαδερμική χορήγηση των ασθενών βάσεων είναι αρκετά υψηλότερα συγκριτικά με τη χορήγηση των αντίστοιχων αλάτων. Επιπλέον, η χορήγηση της δραστικής ουσίας Α είναι εφικτή από ΔΘΣ τύπου δεξαμενής ενώ η δραστική ουσία Β απαιτεί περαιτέρω μελέτη για αξιολόγηση της διαδερμικής διαπερατότητάς της.Transdermal administration of active pharmaceutical ingredients (APIs), if achievable, presents considerable advantages compared to conventional routes of administration, i.e. oral and intravenous routes, such as avoiding the first-pass metabolism, provide sustained and constant plasma levels and improving patient compliance. Aim of the present study was to assess the in vitro permeation of APIs with weakly basic character, active substance A and active substance B, through human cadaver epidermis as a preliminary step towards the development of transdermal therapeutic systems (TTSs) with desired release rate. In this context, the effect of some factors, specifically chemical form of APIs, composition of transdermal delivery vehicle and skin from different donors, has been studied. The in vitro transdermal permeation experiments were conducted using modified, vertical Franz type diffusion cells and human epidermis of different donors, female sex. Gels containing active substance A in the form of hydrochloric acid (A-HCl) showed extremely low Q values, the amount of A-HCl penetrating the epidermis per unit area in units of ug/cm2, at 12, 24, 36 and 48 h since the beginning of the experiment. Neither the different organic solvent of the delivery vehicle nor the skin from different donor affected statistically significant its absorption, with the consequence that the flow is in any case insufficient. Gels containing active substance in the form of weak base showed higher Q values at all sampling times, achieving therapeutic levels for more than 48 h following administration of a reservoir-type TTS of less than 12 cm2. Concerning Drug-in-Adhesive (DIA) type TTSs, monolithic patches were not functional due to the volatility of the API at temperature above 35ºC and that was the reason why multilaminate – sandwich patches were tested. However, although the original problem was encountered, there was large deviation in the concentration of active substance A from the theoretical value, possibly due to either the backing membrane or the pressure sensitive adhesive (PSA). Finally, regarding gels containing active substance B in the form of weak base, they did not show sufficient Q values to achieve therapeutic plasma levels from TTSs of acceptable area. In addition, the increasing ethanol content and the corresponding change in API concentration did not show similar effect on the flow rate through the skin. It is concluded, therefore, that plasma levels of APIs following transdermal administration of weak bases are significantly higher compared to the administration of corresponding salts. Furthermore, the administration of active substance A is feasible from reservoir-type TTSs whereas active substance B requires further study to assess its percutaneous permeation

Strain and damage monitoring in CFRP fuselage panels using fiber Bragg grating sensors. Part I: Design, manufacturing and impact testing

This is the first paper of a two-paper series describing design, implementation and validation of a strain and damage monitoring system for CFRP fuselage stiffened panels based on fiber optic Bragg grating sensors. The monitoring system was developed and tested on the basis of three load-scenarios: compression to failure of the undamaged panel, compression to failure of the impacted panel and compression to failure of the impacted and fatigued panel. This paper focuses on the design of the fuselage panel, the design of the monitoring system, the embedment of fiber sensors in the panel during manufacturing and the impact testing. The network of the sensors was designed based on a numerical buckling analysis from which the strain field of the panel was computed as a function of the applied compressive load. Embedment of fiber sensors in the panel was done so as to minimize risk of fiber breaking during manufacturing and impact testing and to effectively capture strains that are representative of damage developed in the panel due to compressive load. Barely visible and visible low velocity impact damage sites were created at different locations of the panel using a drop-weight impactor. The panels were inspected using C-scan just after manufacturing, to check quality of the material, and just after impact testing to detect impact damage at each location

Fairness Aware Counterfactuals for Subgroups

In this work, we present Fairness Aware Counterfactuals for Subgroups (FACTS), a framework for auditing subgroup fairness through counterfactual explanations. We start with revisiting (and generalizing) existing notions and introducing new, more refined notions of subgroup fairness. We aim to (a) formulate different aspects of the difficulty of individuals in certain subgroups to achieve recourse, i.e. receive the desired outcome, either at the micro level, considering members of the subgroup individually, or at the macro level, considering the subgroup as a whole, and (b) introduce notions of subgroup fairness that are robust, if not totally oblivious, to the cost of achieving recourse. We accompany these notions with an efficient, model-agnostic, highly parameterizable, and explainable framework for evaluating subgroup fairness. We demonstrate the advantages, the wide applicability, and the efficiency of our approach through a thorough experimental evaluation of different benchmark datasets

A Case of Meningococcal and HSV-2 Meningitis in a Patient Being Treated with Ustekinumab for Pityriasis Rubra Pilaris

Pityriasis rubra pilaris (PRP) is a rare chronic inflammatory papulosquamous dermatosis affecting both adults and children. Six subtypes of PRP have been described. Recently, the management of PRP with biologic immunosuppressive agents regularly used in psoriasis has been supported by several case reports and series. Ustekinumab is an anti-IL12/23 IgG1 kappa human monoclonal antibody. It has been approved for the treatment of Crohn’s disease, plaque psoriasis, psoriatic arthritis and ulcerative colitis. It has also been reported to be effective as an off-label treatment for PRP. Current data are equivocal regarding infectious disease risk with ustekinumab administration. We describe a case of meningococcal and HSV-2 infection of the central nervous system in a patient being treated with ustekinumab for PRP

A geophysical insight of the lithostratigraphic subsurface of Rodafnidia area (Lesbos Isl., Greece)

The study area of Rodafnidia on the island of Lesbos (Greece) is considered of archaeological interest, as Paleolithic stone tools have been recovered through excavation and collected from the ground surface in recent years. Geologically, the area is mostly covered by Quaternary post-alpine deposits and volcanic rocks. This paper presents the application of a local geophysical survey to determine the volume of the upper Quaternary deposits in which the Paleolithic artefacts can be found and the identification of their ignimbrite substrates. For this reason, the geoelectrical method was selected as the most appropriate for determining the lithostratigraphic subsurface layers. More specifically, a grid of twenty-one (21) Vertical Electrical Soundings (VES) along with an Electrical Resistivity Tomography (ERT) was carried out. The interpretation of the results of these surveys, in conjunction with the results of older excavation trenches, revealed that the Quaternary deposits have been investigated at depths ranging from 0.5 up to 28.5 meters. Furthermore, the lithological boundary of these post-alpine deposits and their underlying pyroclastic ignimbrite flow (with resistivity 24.0–58.0 Ohm.m) seem to dip to the north. The volume of the Quaternary layer is proposed as the maximum depth for archaeological investigation with high chances to recover more Paleolithic material

Intravenous thrombolysis for acute ischemic stroke in Greece: the Safe Implementation of Thrombolysis in Stroke registry 15-year experience

Background: Intravenous thrombolysis (IVT) remains the only approved systemic reperfusion treatment for acute ischemic stroke (AIS), however there are scarce data regarding outcomes and complications of IVT in Greece. We evaluated safety and efficacy outcomes of IVT for AIS in Greece using the Safe Implementation of Thrombolysis in Stroke: International Stroke Thrombolysis Register (SITS-ISTR) dataset. Methods: All AIS patients treated with IVT in Greece between December 2002 and July 2017 and recorded in the SITS-ISTR were evaluated. Demographics, risk factors, baseline stroke severity [defined using National Institutes of Health Stroke Scale (NIHSS)], and onset-to-treatment time (OTT) were recorded. Safety outcomes included symptomatic intracranial hemorrhage (sICH) and 3-month mortality rates. The efficacy outcomes evaluated a reduction in baseline NIHSS score at 2 and 24 h following IVT onset, 3-month favorable functional outcome [FFO; modified Rankin scale (mRS) scores of 0-1] and 3-month functional independence (FI; mRS-scores of 0-2). The safety and efficacy outcomes were assessed comparatively with previously published data from SITS national and international registries. Results: A total of 523 AIS patients were treated with IVT in 12 Greek centers participating in the SITS-ISTR during the study period (mean age 62.4 ± 12.7; 34.6% women; median baseline NIHSS score: 11 points; median OTT: 150 min). The rates of sICH were 1.4%, 2.3%, and 3.8% according to the SIST-MOST, ECASS II, and NINDS criteria respectively. The median reduction in NIHSS score at 2 and 24 h was 3 [interquartile range (IQR): 1-5] and 5 (IQR: 2-8) points respectively. The 3-month FI, FFO and mortality were 66.5%, 55.6% and 7.9%. All safety and efficacy outcomes were comparable with available data from SITS-ISTR in other European countries. Conclusions: Our study underscores the safety and efficacy of IVT for AIS in Greece. Additional action is necessary in order to increase the availability of IVT in the Greek population and to include more centers in the SITS-ISTR

Clinical validation of an algorithm for rapid and accurate automated segmentation of intracoronary optical coherence tomography images

Objectives: The analysis of intracoronary optical coherence tomography (OCT) images is based on manual identification of the lumen contours and relevant structures. However, manual image segmentation is a cumbersome and time-consuming process, subject to significant intra- and inter-observer variability. This study aims to present and validate a fully-automated method for segmentation of intracoronary OCT images. Methods: We studied 20 coronary arteries (mean length = 39.7 ± 10.0 mm) from 20 patients who underwent a clinically-indicated cardiac catheterization. The OCT images (n = 1812) were segmented manually, as well as with a fully-automated approach. A semi-automated variation of the fully-automated algorithm was also applied. Using certain lumen size and lumen shape characteristics, the fully- and semi-automated segmentation algorithms were validated over manual segmentation, which was considered as the gold standard. Results: Linear regression and Bland–Altman analysis demonstrated that both the fully-automated and semiautomated segmentation had a very high agreement with the manual segmentation, with the semi-automated approach being slightly more accurate than the fully-automated method. The fully-automated and semiautomated OCT segmentation reduced the analysis time by more than 97% and 86%, respectively, compared to manual segmentation. Conclusions: In the current work we validated a fully-automated OCT segmentation algorithm, as well as a semiautomated variation of it in an extensive “real-life” dataset of OCT images. The study showed that our algorithm can perform rapid and reliable segmentation of OCT images

Splenic rupture as the presenting manifestation of primary splenic angiosarcoma in a teenage woman: a case report

<p>Abstract</p> <p>Introduction</p> <p>Primary splenic angiosarcoma is a rare neoplasm of vascular origin carrying a very poor prognosis, partly due to its high metastatic potential. This disease presents frequently with splenic rupture and hemorrhage. We report the case of a 17-year-old woman who presented with rupture of a primary splenic angiosarcoma.</p> <p>Case presentation</p> <p>The patient presented with diffuse abdominal pain and distention. Clinical examination revealed severe tenderness in the left upper abdominal quadrant, a palpable abdominal mass, and hemodynamic instability with a systolic arterial blood pressure of 75 mmHg and heart rate of 135 beats per minute. Blood tests revealed anemia (hemoglobin 7.0 g/dl) and thrombocytopenia (platelets 70 × 10⁹/liter). After initial fluid resuscitation and stabilization, abdominal ultrasound and computed tomography were performed, revealing a large quantity of intraperitoneal free fluid, an enlarged spleen, and a heterogeneous low-density signal within the splenic parenchyma, which showed varying degrees of contrast enhancement. At laparotomy a huge (weight 1530 g, diameter 19 cm) actively bleeding spleen was identified and splenectomy was performed. Histopathology showed a primary splenic angiosarcoma. After an uneventful recovery, the patient was discharged on the sixth postoperative day.</p> <p>Conclusion</p> <p>Primary splenic angiosarcoma is rare. Although this malignancy is usually encountered in advanced age, there have been a few reported cases among younger patients. The case reported here presented with splenic rupture, was treated by laparotomy and splenectomy, and the patient is disease free 16 months after surgery.</p