Diversification Across Mining Pools: Optimal Mining Strategies under PoW

Mining is a central operation of all proof-of-work (PoW) based cryptocurrencies. The vast majority of miners today participate in "mining pools" instead of "solo mining" in order to lower risk and achieve a more steady income. However, this rise of participation in mining pools negatively affects the decentralization levels of most cryptocurrencies. In this work, we look into mining pools from the point of view of a miner: We present an analytical model and implement a computational tool that allows miners to optimally distribute their computational power over multiple pools and PoW cryptocurrencies (i.e. build a mining portfolio), taking into account their risk aversion levels. Our tool allows miners to maximize their risk-adjusted earnings by diversifying across multiple mining pools which enhances PoW decentralization. Finally, we run an experiment in Bitcoin historical data and demonstrate that a miner diversifying over multiple pools, as instructed by our model/tool, receives a higher overall Sharpe ratio (i.e. average excess reward over its standard deviation/volatility).Comment: 13 pages, 16 figures. Presented at WEIS 201

Aural evolutions: intersections of sound with the physical space

This is a practice-based research project situated at an intersection between the fields of electroacoustic composition, experimental composition, and sound art. The general research context for this project is a territory that engages with sound as a physical medium, and is concerned with the representation of acoustic phenomena through sound art and experimental composition. Practitioners in this territory include Alvin Lucier, Sato Minoru and Carsten Nicolai. The present study extends this territory in order to focus on the representation of mechanisms that affect the evolution of a sound from the moment it is produced and until it reaches our perception. Each work presented in this thesis deals with the representation of specific elements of an acoustic phenomenon that are capable of shaping the form of a sound. In doing so, this research project contributes with an original portfolio of works that explore the representation of elements such as the relationship of the size of a space with the frequency of a sound that is produced inside this space. As a result from this process, this study exposes intersections and analogies between the material and the energetic space as they are manifested by the evolution of sound as a physical phenomenon, and engages the audience in experiencing the meeting points of these two spaces

PHYSIOLOGICAL CHARACTERISTICS OF GREEK SOCCER REFEREES OF PROFESSIONAL AND AMATEUR CATEGORIES

Aim: The aim of this study was to examine the physiological characteristics of Greek soccer referees in professional and amateur categories. Material and methods: Twenty Greek soccer referees (10 amateur, 10 professional level) underwent laboratory evaluation to determine anthropometrical characteristics, cardiorespiratory endurance parameters, anaerobic alactic power, maximal power for the knee extensors and flexors, leg explosive power and optical stimulus reaction time. Results: Mean values of body weight (78,22 ± 6.87 v 90,5 ± 15,66), relative lower limb power (10,3 ± 0,85 v 9,47 ± 1), peak oxygen intake (54,96 ± 4,88 v 45,79 ± 4,58), speed of peak oxygen intake (16,54 ± 0,88 v 14,06 ± 1,55), speed of anaerobic threshold (12,4 ± 0,81 v 10,6 ± 1,13), maximum power of right leg knee extensors (356,2 ± 62,7 v 421,3 ± 84,4)  and left leg knee flexors were different (276,8 ± 39,48 v 308,1 ± 37,51) (p < 0.05) between professional and amateur referees. No significant differences (p > 0.05) were observed for mean age (31,4 ± 3,66 26,7 ± 6,11), height (179,8 ± 4,96 v 181,00 ± 4,50),  % fat (17,51 ± 2,36 v 20,39 ± 5,4), flexibility (18,6 ± 5,82 v 13,4 ± 9,96), anaerobic alactic power (804,8 ± 93,4 v 846 ± 97,8), maximal leg frequency (181,3 ± 20,65 v 180,7 ± 11,59), leg explosive force (31,4 ± 4,33 v 30,48 ± 2,68), reaction time (0,24 ± 0,03 v 0,24 ± 0,03), maximum heart rate (184,4 ± 11,44 v 188,2 ± 10,11) maximal blood lactate concentration (9,62 ± 2,71 v 9,47 ± 2,65) maximum left leg knee extending power (369,3 ± 74,34 v 422,7 ± 97,24) as well as right leg flexors (274,9 ± 26,13 v 298,1 ± 51) and the relative power of left and right lower limb extensors and flexors(4,55 ± 0,70 v 4,66 ± 0,63), (4,73 ± 0,84 v 4,67 ± 0,77), (3,52 ± 0,29 v 3,32 ± 0,48), (3,55 ± 0,49 v 3,47 ± 0,53) respectively. Conclusions: Professional-level referees compared to referees who manage games in amateur categories, mainly present increased cardiorespiratory endurance parameters. This difference can be attributed to the long-term systematic preparation and their frequent periodic fitness level examinations by the federation with fitness tests that are also a criterion of failure from this level of refereeing.  Article visualizations

The geothermal occurrence of Kapistri, Ierapetra area, Crete

Η γεωθερμική εμφάνιση εντοπίζεται κοντά στο χωριό Καπίστρι, στην ευρύτερη περιοχή της πόλης της Ιεράπετρας στο νομό Λασηθίου της Κρήτης. Σε μερικές υδρογεωτρήσεις μετρήθηκαν θερμοκρασίες περί τους 25οC σε βάθος 100 – 150 μ. από την επιφάνεια. Η γεωθερμική βαθμίδα που υπολογίστηκε είναι διπλάσια της κανονικής.H Περιοχή καλύπτεται από πλακώδεις ασβεστολίθους της αυτόχθονης σειράς της Κρήτης πάνω στην οποία είναι επωθημένες μονάδες της φυλλιτικής – χαλαζιτικής σειράς και των ζωνών Πίνδου και Τριπόλεως. Εντός των ασβεστολίθων έχουν διεισδύσει μαγματικά πετρώματα (γρανιτοειδή) που έχουν προκαλέσει μεταμόρφωση επαφής και ρηγμάτωση κοντά στο Καπίστρι. Έντονη τεκτονική δραστηριότητα παρατηρείται στην ευρύτερη λεκάνη Ιεράπετρας με κύριες διευθύνσεις των ρηγμάτων Β – Ν, Α – Δ, ΒΔ – ΝΑ και ΒΑ – ΝΔ.Η αυξημένη γεωθερμική βαθμίδα, η έντονη ρηγμάτωση της περιοχής και η γεωχημική ένδειξη για την παρουσία νερού που κυκλoφορεί σε μεγάλο βάθος δείχνουν την πιθανή ανάπτυξη ενός βαθύτερου γεωθερμικού πεδίου.The geothermal occurence is located close to the Kapistri village, Ierapetra town, prefecture of Lassithi. In some water wells temperature of about 25oC in a depth of 100 - 150 m below surface, were measured. The calculated geothermal gradient is thus double in size compared to normal gradient.The geological environment is composed of platy limestones of the autochthonous series of Crete on which units of phyllite – quartzite series as well as Pindos and Tripoli zones are overthrusted. Granite intrusion occurs in the carbonates with distinct contact metamorphism, in the Kapistri area. Intense tectonic activity is observed in the wider area of the Ierapetra graben with main fault direction N – S, E –W, NW – SE, and NE – SW.The elevated geothermal gradient, the intense faulting of the area and the existence of deep circulated water indicates the development of a deeper geothermal field

A METHOD AND SYSTEM TO IMPLEMENT ADAPTIVE TRAINING ALGORITHM: ADAM Q

The present disclosure relates to providing a method and system for training neural networks. It discloses an adaptive training algorithm Adam Q to overcome the challenges associated with its predecessors. It proposes a look-up table to be fused with the existing Adam algorithm such that Adam Q may not need to run all the computational operations while determining the updated weights and instead may directly see the results from the fused look-up table. It further goes on to propose a quantization technique where the received inputs from the previous iterations are first quantized and then taken as an input for the provided look-up table to make the proposed algorithm more efficient. Thus, by subjecting the inputs to quantization and fusing the look-up table, Adam Q aims to provide a more computationally efficient and financially sustainable way while ensuring data privacy

MiniLedger: Compact-sized Anonymous and Auditable Distributed Payments

While privacy preserving distributed payment schemes manage to drastically improve user privacy, they come at the cost of generating new regulatory concerns: in a private ledger the transactions cannot be subject to any level of auditing, and thus are not compatible with tracing illegal behaviors. In this work we present MiniLedger, a distributed payment system which not only guarantees the privacy of transactions, but also offers built-in functionalities for various types of audits by any external authority. MiniLedger is the first private and auditable payment system with storage costs independent of the number of transactions. To achieve such a storage improvement, we introduce pruning functionalities for the transaction history while maintaining integrity and auditing. We provide formal security definitions and a number of extensions for various auditing levels. Our evaluation results show that MiniLedger is practical in terms of storage requiring as low as 70KB per participant for 128 bits of security, and depending on the implementation choices, can prune 1 million transactions in less than a second

CORPORATE STRATEGIC CHANGE IN SMALL BUSINESS: AN APPLICATION OF ACTION RESEARCH FOR THE DEVELOPMENT OF INTERNAL MARKETING DURING STRATEGIC CHANGE

For this action research study, the researcher studied a small business services firm in the United States of America, as they embarked on a strategic change to develop their structure, processes, and internal communication strategy. The author aimed to develop proposals for the company's business owners to evaluate more pluralistic methods for developing and communicating business change using internal marketing and their employees’ participation. This academic inquiry evaluated, within the context of the presented literature, the actions taken by the firm's business owners in their approach to reform the company and how their strategy was received and affected their employees. Specifically, the researcher studied and analyzed the employees’ views regarding the firm’s strategic planning, internal communication, and participative management processes during the strategic change to assess why the studied organization’s current practices did not adequately communicate the change objectives to reduce employee confusion and business disruption

A Study of Common Denominators of Management: Transferable Attributes of Management from the Military to the Civilian Environment

Management research has long been the focus of researchers and academics who strive to identify and suggest qualities that enable the former along with management practitioners and public and private institutions to achieve maximum stakeholder return. The writer aimed to suggest common attributes of management that can be practiced and developed between the military and civilian environments. In pursuing this research, the author chose to conduct an in-depth analysis of a variety of competencies that are developed in the two environments and how they can be applied to the aforesaid frameworks. To achieve the latter, the researcher chose to employ the qualitative research method as it is linked mainly with the investigations of human relations and corporate and public management structures. By utilizing qualitative research techniques, the writer capitalized upon prior debates surrounding the focus of the study and current research data. A range of relationships were examined in connection with the management discipline such as academic background of the executives, previous experiences of the latter, their influence in new managerial positions, military history, the relationship between leadership and management and weaknesses and strengths of the military and civilian organizations. The complexities that were revealed were analyzed and weaknesses regarding research were identified and accounted for. Further research opportunities were flagged for supplementary investigation by combining additional frameworks of the management art and by employing comprehensive triangulation research methods

Base64 Malleability in Practice

Base64 encoding has been a popular method to encode binary data into printable ASCII characters. It is commonly used in several serialization protocols, web, and logging applications, while it is oftentimes the preferred method for human-readable database fields. However, while convenient and with a better compression rate than hex-encoding, the large number of base64 variants in related standards and proposed padding-mode optionality have been proven problematic in terms of security and cross-platform compatibility. This paper addresses a potential attack vector in the base64 decoding phase, where multiple different encodings can successfully decode into the same data, effectively breaking string uniqueness guarantees. The latter might result to log mismatches, denial of service attacks and duplicated database entries, among the others. Apart from documenting why canonicity can be broken by a malleable encoder, we also present an unexpected result, where most of today\u27s base64 decoder libraries are not 100% compatible in their default settings. Some surprising results include the non-compatible behavior of major Rust base64 crates and between popular Javascript and NodeJS base64 implementations. Finally, we propose ways and test vectors for mitigating these issues until a more permanent solution is widely adopted