Steady state analysis of balanced-allocation routing

We compare the long-term, steady-state performance of a variant of the standard Dynamic Alternative Routing (DAR) technique commonly used in telephone and ATM networks, to the performance of a path-selection algorithm based on the "balanced-allocation" principle; we refer to this new algorithm as the Balanced Dynamic Alternative Routing (BDAR) algorithm. While DAR checks alternative routes sequentially until available bandwidth is found, the BDAR algorithm compares and chooses the best among a small number of alternatives. We show that, at the expense of a minor increase in routing overhead, the BDAR algorithm gives a substantial improvement in network performance, in terms both of network congestion and of bandwidth requirement.Comment: 22 pages, 1 figur

New Balkan records of Bombus subterraneus (Linnaeus 1758) and Bombus cryptarum (Fabricius 1775) from Greece

Από τη μελέτη των βομβίνων της Ελλάδος, έχουν δημοσιευθεί από το 1995 και μετά καταστάσεις των ειδών οι οποίες είχαν βασιστεί για τη σύνταξη τους σε δημοσιευμένες καταγραφές των εντόμων αλλά και σε πρωτογενή συλλεγμένο υλικό. Η καταγραφή πληροφοριών σχετικά με τους βομβίνους στην Ελλάδα, εκτός των άλλων, εστιάζεται και στον εντοπισμό των καταγραμμένων μοναχά στη βιβλιογραφία ειδών για την επιβεβαίωση της ύπαρξης τους με νέες πλέον καταγραφές. Στην προσπάθεια αυτή, πολλοί βομβίνοι συλλέχθηκαν και εξετάστηκαν και σε ορισμένες περιπτώσεις καταγράφηκαν νέα για την Ελλάδα είδη Bombus. Υπάρχουν όμως είδη, κυρίως από παλιές βιβλιογραφικές πηγές, που δεν έχουν ξαναβρεθεί γεγονός που καθιστά την ύπαρξη τους ή μη στην σύγχρονη Ελλάδα ένα υπό έρευνα αντικείμενο. Με την εξέταση βομβίνων που συλλέχτηκαν κατά τα έτη 2006 και 2007 στον νομό της Φλώρινας προέκυψαν πρόσφατα πρωτογενής πληροφορίες για δύο είδη «βιβλιογραφικών» βομβίνων, τα Bombus subterraneus (Linnaeus 1758) και Bombus cryptarum (Fabricius 1775). Βασίλισσα του B. subterraneus (που συλλέχτηκε 40°47´38N, 21°26´10E επί Vicia cracca) αναγνωρίστηκε χρησιμοποιώντας μορφολογικά χαρακτηριστικά και εργάτρια του B. cryptarum (που συλλέχτηκε 40°41´58,7N, 21°28´18,5E επί Echium spp) καθορίστηκε με μιτοχονδριακό DNA RFLP ανάλυση του CO1 γονιδίου. Οι νέες αυτές καταγραφές βομβίνων από την περιοχή του νομού Φλώρινας επιβεβαιώνουν τη παρουσία των δύο ειδών Bombus στην Ελλάδα μετά από περίπου 40 χρόνια και παρουσιάζονται στην παρούσα εργασία με σχετικά σχόλια.From the study of the Greek bumblebee fauna (Hymenoptera: Apidae, Bombini), species lists have been published based on both literature records and original data from collected bees. Since 1995 a special effort to confirm with newly collected bees all bumblebee species reported in literature records for Greece has been in progress. Although numerous specimens have been collected and examined and in some instances yielding new Bombus species for the Greek insect fauna, some species, mainly those reported in older references, have not yet been found. Recently, identification of bumblebees collected in the Florina Prefecture - Northwest Macedonia, during the years 2006 and 2007 yielded information for two “literature cited” species, Bombus subterraneus (Linnaeus 1758) and Bombus cryptarum (Fabricius 1775). A B. subterraneus queen (collected at 40°47´38N, 21°26´10E on Vicia cracca) was distinguished by morphological characteristics and a worker B. cryptarum (collected at 40°41´58,7N, 21°28´18,5E on Echium spp) was revealed using mitochondrial DNA RFLP analysis of the CO1 gene. These new records from Florina are provided with comments, confirming the species presence in Greece for the first time after approximately 40 years

Low-Quality Dimension Reduction and High-Dimensional Approximate Nearest Neighbor

The approximate nearest neighbor problem (epsilon-ANN) in Euclidean settings is a fundamental question, which has been addressed by two main approaches: Data-dependent space partitioning techniques perform well when the dimension is relatively low, but are affected by the curse of dimensionality. On the other hand, locality sensitive hashing has polynomial dependence in the dimension, sublinear query time with an exponent inversely proportional to (1+epsilon)^2, and subquadratic space requirement. We generalize the Johnson-Lindenstrauss Lemma to define "low-quality" mappings to a Euclidean space of significantly lower dimension, such that they satisfy a requirement weaker than approximately preserving all distances or even preserving the nearest neighbor. This mapping guarantees, with high probability, that an approximate nearest neighbor lies among the k approximate nearest neighbors in the projected space. These can be efficiently retrieved while using only linear storage by a data structure, such as BBD-trees. Our overall algorithm, given n points in dimension d, achieves space usage in O(dn), preprocessing time in O(dn log n), and query time in O(d n^{rho} log n), where rho is proportional to 1 - 1/loglog n, for fixed epsilon in (0, 1). The dimension reduction is larger if one assumes that point sets possess some structure, namely bounded expansion rate. We implement our method and present experimental results in up to 500 dimensions and 10^6 points, which show that the practical performance is better than predicted by the theoretical analysis. In addition, we compare our approach with E2LSH

Fintech and regtech : impact on regulators and banks

The last crisis has exposed significant failures of regulation and supervision, making the Financial Market Law and Compliance a key topic on the agenda. Great changes and challenges lie ahead of us soon to be realized. The preparedness of the regulators to instil culture change and harmonise technological advancements with regulation as the financial services industry evolves would likely ensure its orderly growth, systemic stability, trust in the financial system and thereby would also help to address various political, social and economic issues for a variety of stakeholders. This paper specifies theoretical and practical guidelines. These should be of interest to regulatory standard setters, global investors, international organizations and other academics who are researching regulatory and competition issues and their manifestation within the financial and social contexts. The study has the potential of welfare outcomes for consumers, regulatory and supervisory gains and reputational gains for the financial services industry. Our interpretative results have implications for both research and practice. Disruptive change seems to be important in investigating regulatory compliance followed by change; we contribute to the current literature review on financial and digital innovation by new entrants where this has also practical implications. As a perspective on a social construct, this study appeals to regulators and law makers, entrepreneurs and investors who participate in technology applied within the innovative financial services domain and bankers that might consider FinTech and strategic partnerships as potential future strategic direction. The difficulties arising from extensive regulation suggest a more liberal and principled approach to financial regulation. This paper is also an updated review of the current regulatory issues addressing the contextual root causes of disruption within the financial services context aiming to assist market participants to improve effectiveness and collaboration