Health and Migration: Health Securitization and Policy-Making Perspectives in the Post-Pandemic Era

It is not to deny that the up-to-date literature has already discussed the emergence of forced human mobility due to the outbreak of health crises, owing to the latter’s adverse socio-political effects on the intrastate or regional systems. However, the ongoing COVID-19 pandemic has been playing a crucial role in enhancing the research upon health crises and health securitization, hence, further recognizing their multidimensional character. Under these circumstances, this text attempts to estimate whether and to what extent the states will reconsider their agendas –in the post-pandemic era– in terms of more successfully managing health crises and associated migration, so as to respectively reduce the potential negative consequences in their internal systems

Parametric Sensitivity Analysis for Biochemical Reaction Networks based on Pathwise Information Theory

Stochastic modeling and simulation provide powerful predictive methods for the intrinsic understanding of fundamental mechanisms in complex biochemical networks. Typically, such mathematical models involve networks of coupled jump stochastic processes with a large number of parameters that need to be suitably calibrated against experimental data. In this direction, the parameter sensitivity analysis of reaction networks is an essential mathematical and computational tool, yielding information regarding the robustness and the identifiability of model parameters. However, existing sensitivity analysis approaches such as variants of the finite difference method can have an overwhelming computational cost in models with a high-dimensional parameter space. We develop a sensitivity analysis methodology suitable for complex stochastic reaction networks with a large number of parameters. The proposed approach is based on Information Theory methods and relies on the quantification of information loss due to parameter perturbations between time-series distributions. For this reason, we need to work on path-space, i.e., the set consisting of all stochastic trajectories, hence the proposed approach is referred to as "pathwise". The pathwise sensitivity analysis method is realized by employing the rigorously-derived Relative Entropy Rate (RER), which is directly computable from the propensity functions. A key aspect of the method is that an associated pathwise Fisher Information Matrix (FIM) is defined, which in turn constitutes a gradient-free approach to quantifying parameter sensitivities. The structure of the FIM turns out to be block-diagonal, revealing hidden parameter dependencies and sensitivities in reaction networks

Focus on the Positives: Self-Supervised Learning for Biodiversity Monitoring

We address the problem of learning self-supervised representations from unlabeled image collections. Unlike existing approaches that attempt to learn useful features by maximizing similarity between augmented versions of each input image or by speculatively picking negative samples, we instead also make use of the natural variation that occurs in image collections that are captured using static monitoring cameras. To achieve this, we exploit readily available context data that encodes information such as the spatial and temporal relationships between the input images. We are able to learn representations that are surprisingly effective for downstream supervised classification, by first identifying high probability positive pairs at training time, i.e. those images that are likely to depict the same visual concept. For the critical task of global biodiversity monitoring, this results in image features that can be adapted to challenging visual species classification tasks with limited human supervision. We present results on four different camera trap image collections, across three different families of self-supervised learning methods, and show that careful image selection at training time results in superior performance compared to existing baselines such as conventional self-supervised training and transfer learning

Charging and Discharging Processes in AlN Dielectric Films Deposited by Plasma Assisted Molecular Beam Epitaxy

In the present work the electrical properties of AlN polycrystalline films deposited at low temperatures by plasma-assisted molecular beam epitaxy (PA-MBE) are investigated. The polarization build-up during constant current injection as well as the depolarization process after the current stress have been investigated through monitoring voltage transients in Metal – Insulator – Metal (MIM) capacitors, in temperature range from 300 K to 400 K. Moreover, current – voltage characteristics obtained at different temperatures revealed that charge collection at low fields in these films occurs through variable range hopping

Static and dynamic slope analysis with finite element method

180 σ.Η μέθοδος των Πεπερασμένων Στοιχείων αποτελεί ένα ισχυρό εργαλείο για κάθε μηχανικό. Με την ανάπτυξη των τεχνολογιών και της υπολογιστικής ισχύς η μέθοδος έγινε πιο γρήγορη, πιο ακριβής και το φάσμα χρήσης της πιο ευρύ. Υπό αυτό το πρίσμα κάθε γεωτεχνικό πρόβλημα μπορεί να επιλυθεί με την μέθοδο των Πεπερασμένων Στοιχείων. Άλλωστε οι ιδιαιτερότητες που παρουσιάζουν τα γεωτεχνικά προβλήματα είναι τέτοιες που οι υπολογισμοί τους πρέπει να αναπαριστούν πλήρως την πραγματικότητα και να προβλέπουν με ακρίβεια τις επιπτώσεις κάθε μελέτης. Το αντικείμενο της παρούσας διπλωματικής εργασίας αποτελεί την ανάλυση της συμπεριφοράς διαφόρων πρανών υπολογισμένα με την μέθοδο των Πεπερασμένων Στοιχείων (ΜΠΣ), με το πρόγραμμα PLAXIS v.9 να χρησιμοποιείται ως εργαλείο για την πραγματοποίηση της μεθόδου. Όλα τα πρανή που αναλύονται είχαν επιλυθεί αρχικά με άλλες μεθόδους, είτε αριθμητικές είτε εργαστηριακές. Σκοπός, ήταν η σύγκριση αυτών των μεθόδων, έτσι ώστε να ελεγχτεί η ακρίβεια της μεθόδου αλλά και να επιβεβαιωθούν και οι προηγούμενες μελέτες. Κύριος τρόπος σύγκρισης των μεθόδων αυτών ήταν μέσω των Συντελεστών Ασφαλείας και της επιφάνειας αστοχίας του κάθε πρανούς. Τα αποτελέσματα ήταν εντυπωσιακά καθώς όλες οι επιλύσεις με την ΜΠΣ συμφώνησαν με τις υπάρχουσες μελέτες. Περαιτέρω αναλύσεις διεξήχθησαν στην επίλυση αυτών των πρανών. Συγκεκριμένα μελετήθηκε η ευστάθεια τους υπό συνθήκες σεισμού. Η εισαγωγή του σεισμού έγινε με δύο τρόπους. Αρχικά, έγινε ψευδοστατικά με την εφαρμογή στο μοντέλο σεισμικής επιτάχυνσης εδάφους, όπως αυτή ορίζεται από τον ΕΑΚ 2000 στις Ζώνες Σεισμικής Επικινδυνότητας. Δευτερευόντως, με δυναμική ανάλυση μέσω της εισαγωγής σεισμικής διέγερσης ενός πραγματικού σεισμού, που ενεργοποιήθηκε στις 28/2/1990 στην Νότια Καλιφόρνια. Η εισαγωγή της έγινε μέσω ενός επιταχυνσιογραφήματος και μελετήθηκε για διάρκεια σεισμού 10 sec και 23,5 sec αντίστοιχα. Σκοπός ήταν η μελέτη συμπεριφοράς των πρανών υπό αυτές τις συνθήκες, ενώ έγινε και σύγκριση των αποτελεσμάτων μεταξύ των δύο μεθόδων σε ορισμένα από αυτά τα πρανή. Βάση των εξαγόμενων αποτελεσμάτων οι δύο μέθοδοι παρουσιάζουν διαφορές ως προς το αποτέλεσμα, καθώς η δυναμική μέθοδος θα μπορούσε να χαρακτηριστεί πιο ακριβής για την μελέτη συμπεριφοράς ενός ήδη γνωστού σεισμού. Αντιθέτως, η ψευδοστατική είναι πιο γενική και συντηρητική μέθοδος, που για αυτό τον λόγο όμως την κάνει πιο εύχρηστη. Τέλος, σε μερικά πρανή υπολογίστηκε η ευστάθεια τους και σε υπό συνθήκες εξωγενής φόρτισης στην επιφάνεια τους πέρα από την επίδραση του εδαφικού βάρους. Κατ΄αυτό τον τρόπο εισήχθησαν στα μοντέλα γραμμικά φορτία, πλάκες και ολόκληρα κτήρια. Η σύγκριση της ευστάθειας για όλες αυτές τις περιπτώσεις επέφερε σημαντικά αποτελέσματα αποδεικνύοντας ότι επιπλέον φορτίσεις στην επιφάνεια του πρανούς είτε αυτό είναι ένα κτήριο είτε οποιασδήποτε άλλης μορφής προκαλούν μείωση της ευστάθειας του, η οποία βεβαίως εξαρτάται σε ποιο σημείο εφαρμόζεται και αν βρίσκεται κοντά ή όχι στην στέψη του πρανούς.The Finite Element Method is a powerful tool for every engineer. Due to the technology evolution and computing power the method has become faster, more accurate and the use range more wide. Under these circumstances every geotechnical problem can resolve with Finite Element Method. Besides, much specificity is presented in geotechnical problems and the calculations should totally represent the reality and predict with accuracy the consequences of every study. The main subject of the present Diploma Thesis is the behavior analysis of different slopes calculated with the Finite Element Method (FEM), where the calculation program PLAXIS v.9 is used as tool to carry out the method. All the analyzed slopes have been solved with other methods, numerical or on lavatory. The purpose is to compare those methods, in order to check the accuracy of FEM and to confirm the previous studies. Main comparison way is through the Safety Factors and the failure surface of every slope. The results were impressive, thus all the solutions with Finite Element Method were the same with the existing studies. Further analysis contacted to solve these slopes. Specifically, slope stability was studied under seismic conditions. Initially, it was conducted a pseudo-static by inputting seismic soil acceleration, as it is defined in the Hellenic Seismic Code 2000 for every Zone of Seismic Risk. Secondly, a dynamic analysis was conducted through a seismic stimulation of a real earthquake; this took place in 28/2/1990 in Southern California. The input of the earthquake was realized using an acceleration graphic and the duration of the earthquake was 10 seconds and 23.5 seconds. The purpose was the study of the slope behavior under those circumstances, while a result comparison was made between those two methods. Based on the output results the two methods have result differences. While the dynamic analysis could be described as more accurate for a study of a known earthquake, the pseudo-static is more generalized and conservative and that is why is more useful. Finally, some slopes were calculated for their stability under an extrinsic charging in their surface, besides the effects of the soil weight. By those linear charges, plates and building were inputted. The stability comparison for all these cases bought significant results, proving that those additional charges provoke stability reduction, which of course depends in which point is applied and if it near in slope’s coronation.Ευάγγελος Γ. Πανταζή

Inhibition of angiogenesis- and inflammation-inducing factors in human colon cancer cells in vitro and in ovo by free and nanoparticle-encapsulated redox dye, DCPIP

<p>Abstract</p> <p>Background</p> <p>The redox dye, DCPIP, has recently shown to exhibit anti-melanoma activity <it>in vitro </it>and <it>in vivo</it>. On the other hand, there is increasing evidence that synthetic nanoparticles can serve as highly efficient carriers of drugs and vaccines for treatment of various diseases. These nanoparticles have shown to serve as potent tools that can increase the bioavailability of the drug/vaccine by facilitating absorption or conferring sustained and improved release. Here, we describe results on the effects of free- and nanoparticle-enclosed DCPIP as anti-angiogenesis and anti-inflammation agents in a human colon cancer HCT116 cell line <it>in vitro</it>, and in induced angiogenesis <it>in ovo</it>.</p> <p>Results</p> <p>The studies described in this report indicate that (a) DCPIP inhibits proliferation of HCT116 cells <it>in vitro</it>; (b) DCPIP can selectively downregulate expression of the pro-angiogenesis growth factor, VEGF; (c) DCPIP inhibits activation of the transcriptional nuclear factor, NF-κB; (d) DCPIP can attenuate or completely inhibit VEGF-induced angiogenesis in the chick chorioallantoic membrane; (e) DCPIP at concentrations higher than 6 μg/ml induces apoptosis in HCT116 cells as confirmed by detection of caspase-3 and PARP degradation; and (f) DCPIP encapsulated in nanoparticles is equally or more effective than free DCPIP in exhibiting the aforementioned properties (a-e) in addition to reducing the expression of COX-2, and pro-inflammatory proteins IL-6 and IL-8.</p> <p>Conclusions</p> <p>We propose that, DCPIP may serve as a potent tool to prevent or disrupt the processes of cell proliferation, tissue angiogenesis and inflammation by directly or indirectly targeting expression of specific cellular factors. We also propose that the activities of DCPIP may be long-lasting and/or enhanced if it is delivered enclosed in specific nanoparticles.</p