On the Efficiency of All-Pay Mechanisms.

We study the inefficiency of mixed equilibria, expressed as the price of anarchy, of all-pay auctions in three different environments: combinatorial, multi-unit and single-item auctions. First, we consider item-bidding combinatorial auctions where m all-pay auctions run in parallel, one for each good. For fractionally subadditive valuations, we strengthen the upper bound from 2 [22] to 1.82 by proving some struc- tural properties that characterize the mixed Nash equilibria of the game. Next, we design an all-pay mechanism with a randomized allocation rule for the multi-unit auction. We show that, for bidders with submodular valuations, the mechanism admits a unique, 75% efficient, pure Nash equilibrium. The efficiency of this mechanism outperforms all the known bounds on the price of anarchy of mechanisms used for multi-unit auc- tions. Finally, we analyze single-item all-pay auctions motivated by their connection to contests and show tight bounds on the price of anarchy of social welfare, revenue and maximum bid

Improving the Price of Anarchy for Selfish Routing via Coordination Mechanisms

We reconsider the well-studied Selfish Routing game with affine latency functions. The Price of Anarchy for this class of games takes maximum value 4/3; this maximum is attained already for a simple network of two parallel links, known as Pigou's network. We improve upon the value 4/3 by means of Coordination Mechanisms. We increase the latency functions of the edges in the network, i.e., if $\ell_e(x)$ is the latency function of an edge $e$, we replace it by $\hat{\ell}_e(x)$ with $\ell_e(x) \le \hat{\ell}_e(x)$ for all $x$. Then an adversary fixes a demand rate as input. The engineered Price of Anarchy of the mechanism is defined as the worst-case ratio of the Nash social cost in the modified network over the optimal social cost in the original network. Formally, if \CM(r) denotes the cost of the worst Nash flow in the modified network for rate $r$ and \Copt(r) denotes the cost of the optimal flow in the original network for the same rate then [\ePoA = \max_{r \ge 0} \frac{\CM(r)}{\Copt(r)}.] We first exhibit a simple coordination mechanism that achieves for any network of parallel links an engineered Price of Anarchy strictly less than 4/3. For the case of two parallel links our basic mechanism gives 5/4 = 1.25. Then, for the case of two parallel links, we describe an optimal mechanism; its engineered Price of Anarchy lies between 1.191 and 1.192.Comment: 17 pages, 2 figures, preliminary version appeared at ESA 201

Divergent Innate and Epithelial Functions of the RNA-Binding Protein HuR in Intestinal Inflammation

HuR is an abundant RNA-binding protein acting as a post-transcriptional regulator of many RNAs including mRNAs encoding inflammatory mediators, cytokines, death signalers and cell cycle regulators. In the context of intestinal pathologies, elevated HuR is considered to enhance the stability and the translation of pro-tumorigenic mRNAs providing the rationale for its pharmacological targeting. However, HuR also possesses specific regulatory functions for innate immunity and cytokine mRNA control which can oppose intestinal inflammation and tumor promotion. Here, we aim to identify contexts of intestinal inflammation where the innate immune and the epithelial functions of HuR converge or diverge. To address this, we use a disease-oriented phenotypic approach using mice lacking HuR either in intestinal epithelia or myeloid-derived immune compartments. These mice were compared for their responses to (a) Chemically induced Colitis; (b) Colitis- associated Cancer (CAC); (c) T-cell mediated enterotoxicity; (d) Citrobacter rodentium-induced colitis; and (e) TNF-driven inflammatory bowel disease. Convergent functions of epithelial and myeloid HuR included their requirement for suppressing inflammation in chemically induced colitis and their redundancies in chronic TNF-driven IBD and microbiota control. In the other contexts however, their functions diversified. Epithelial HuR was required to protect the epithelial barrier from acute inflammatory or infectious degeneration but also to promote tumor growth. In contrast, myeloid HuR was required to suppress the beneficial inflammation for pathogen clearance and tumor suppression. This cellular dichotomy in HuR's functions was validated further in mice engineered to express ubiquitously higher levels of HuR which displayed diminished pathologic and beneficial inflammatory responses, resistance to epithelial damage yet a heightened susceptibility to CAC. Our study demonstrates that epithelial and myeloid HuR affect different cellular dynamics in the intestine that need to be carefully considered for its pharmacological exploitation and points toward potential windows for harnessing HuR functions in intestinal inflammation

Προσδιορισμός των διαφορών μεταξύ του επιπέδου των ομάδων που συμμετέχουν στους ολυμπιακούς αγώνες και της τελικής τους κατάταξης

Ο σκοπός της παρούσας έρευνας ήταν να εξετάσει κατα πόσο υπάρχουν στατιστικώς σημαντικές διαφορές μεταξύ του επιπέδου των ομάδων που συμμετέχουν στους Ολυμπιακούς αγώνες και της τελικής τους κατάταξης, καθώς και η σύγκριση των 4 τελευταίων Ολυμπιάδων (Ρίο 2016, Λονδίνο 2012, Πεκίνο 2008 και Αθήνα 2004). Χρησιμοποιήθηκαν τα επίσημα στατιστικά αποτελέσματα της Διεθνούς Ομοσπονδίας Χειροσφαίρισης (IHF) τόσο για την καταγραφή της απόδοσης των ομάδων, όσο και για την καταγραφή της απόδοσης των τερματοφυλάκων. Σε πρώτη φάση εξετάστηκαν οι διαφορές που υπάρχουν μεταξύ του επιπέδου των ομάδων και της τελικής τους θέσης στην κατάταξη, και σε δεύτερη οι διαφορές στις παραμέτρους των ομάδων ανα Ολυμπιάδα. Τα αποτελέσματα έδειξαν ότι το υψηλό ποσοστό ευστοχίας απο τα εξτρέμ είναι πολύ σημαντική παράμετρος και μπορεί να ανεβάσει το επίπεδο μιάς ομάδας που συμμετέχει στους Ολυμπιακούς Αγώνες σύμφωνα με τον συντελεστή σημαντικότητας (p < .05). Τα στατιστικά των λαθών δε φαίνεται να επηρεάζουν την τελική κατάταξη ενώ όσο μεγαλύτερος είναι ο αριθμός στις ασσίστ, τόσο πιο ψηλό φαίνεται να είναι το επίπεδο μιάς ομάδας. Η αποτελεσματικότητα των τερματοφυλάκων στις επεμβάσεις τους στα σούτ που τους γίνονται και ιδιαίτερα στα σούτ απο τα 9 μέτρα είναι πολύ σημαντικός παράγοντας στην έκβαση ενός αγώνα και παίζει σημαντικό ρόλο στο επίπεδο μεταξύ των ομάδων. Αξιοσημείωτες ήταν και οι διαφορές μεταξύ των ομάδων που συμμετέχουν ανα ολυμπιάδα. Στην τελευταία Ολυμπιάδα που έγινε στο Ρίο το καλοκαίρι του 2016, οι ομάδες που συμμετείχαν επιχείρησαν να σκοράρουν περισσότερο απο τα 6 μέτρα και λιγότερο απο τα 9 μέτρα σε σχέση με τις προηγούμενες Ολυμπιάδες. Αυτό σημαίνει ότι οι προπονητές αφιέρωσαν περισσότερο χρόνο στο γύρισμα της μπάλας ψάχνοντας άλλες λύσεις όπως η αποτελεσματικότητα στους αιφνιδιασμούς. Οι προπονητές στην τελευταία Ολυμπιάδα κατάφεραν να μειώσουν τα λάθη σε σχέση με άλλες Ολυμπιαδες, παρολαυτά τα κλεψίματα και τα μπλόκ κρατήθηκαν σε πολύ χαμηλότερα επίπεδα συγκριτικά με τις προηγούμενες. Τέλος, οι τερματοφύλακες δεν παρουσιάζουν στατιστικώς σημαντικές διαφορές μέσα απο τις ομάδες που συμμετέχουν στις 4 τελευταίες Ολυμπιάδες. Τα αποτελέσματα αυτά παρουσιάζουν σημαντικές πληροφορίες στους προπονητές χειροσφαίρισης των γυναικείων ομάδων και αποτελούν μιά καλή βάση για περαιτέρω έρευνα.οχ

Submicron aerosol pollution in Greater Cairo (Egypt): A new type of urban haze?

International audienc

Genomic Epidemiology of the SARS-CoV-2 Epidemic in Cyprus from November 2020 to October 2021: The Passage of Waves of Alpha and Delta Variants of Concern

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in December 2019 resulted in the coronavirus disease 2019 (COVID-19) pandemic, which has had devastating repercussions for public health. Over the course of this pandemic, the virus has continuously been evolving, resulting in new, more infectious variants that have frequently led to surges of new SARS-CoV-2 infections. In the present study, we performed detailed genetic, phylogenetic, phylodynamic and phylogeographic analyses to examine the SARS-CoV-2 epidemic in Cyprus using 2352 SARS-CoV-2 sequences from infected individuals in Cyprus during November 2020 to October 2021. During this period, a total of 61 different lineages and sublineages were identified, with most falling into three groups: B.1.258 & sublineages, Alpha (B.1.1.7 & Q. sublineages), and Delta (B.1.617.2 & AY. sublineages), each encompassing a set of S gene mutations that primarily confer increased transmissibility as well as immune evasion. Specifically, these lineages were coupled with surges of new infections in Cyprus, resulting in the following: the second wave of SARS-CoV-2 infections in Cyprus, comprising B.1.258 & sublineages, during late autumn 2020/beginning of winter 2021; the third wave, comprising Alpha (B.1.1.7 & Q. sublineages), during spring 2021; and the fourth wave, comprising Delta (B.1.617.2 & AY. sublineages) during summer 2021. Additionally, it was identified that these lineages were primarily imported from and exported to the UK, Greece, and Sweden; many other migration links were also identified, including Switzerland, Denmark, Russia, and Germany. Taken together, the results of this study indicate that the SARS-CoV-2 epidemic in Cyprus was characterized by successive introduction of new lineages from a plethora of countries, resulting in the generation of waves of infection. Overall, this study highlights the importance of investigating the spatiotemporal evolution of the SARS-CoV-2 epidemic in the context of Cyprus, as well as the impact of protective measures placed to mitigate transmission of the virus, providing necessary information to safeguard public health

Remote sensing of environment - integrated approaches

This book covers the latest developments in remote sensing theory and applications by numerous researchers, experts and collaborators of the Remote Sensing and Geo-Environment Lab of the Department of Civil Engineering and Geomatics of the Cyprus University of Technology. The main highlight of this book is combination of several techniques such as satellite remote sensing, field spectroscopy, smart sensors, ground techniques for achieving an integrated method for the systematic monitoring of the environment