925 research outputs found
Factors affecting trust and communication in global virtual teams
No full textAuthor Georgios GousiasMasterarbeit Universität Linz 2022Arbeit auf den öffentlichen PCs in den Bibliotheken der JKU+Medizin abrufba
Factors affecting trust and communication in global virtual teams
No full textAuthor Georgios GousiasMasterarbeit Universität Linz 2022Arbeit auf den öffentlichen PCs in den Bibliotheken der JKU+Medizin abrufba
Improving Round and Communication Metrics in Consensus
No full textByzantine Consensus protocols, aka Byzantine Agreement (BA), Byzantine Broadcast (BB), allow a set of n mutually distrusting parties to share input values and agree on the same output value. Notable practical applications of consensus in blockchains and MPC require efficient, practical implementations of consensus protocols. The rise of blockchain systems and the general trend towards decentralized services, which inherently utilize consensus, as well as the increased demand of consensus as a primitive for implementing other cryptographic protocols (e.g. in MPC), brought once again this topic in the forefront of research.
A recurring trilemma of consensus when utilized in practice is striking the balance in order to construct protocols that are: i) efficient, ii) resilient under harsh adversarial conditions, and iii) with minimal assumptions for the corresponding setting. These properties are usually negatively associated; efficient protocols often either require stronger assumptions, or are less resilient to strong adversaries.
In this dissertation we aim to improve the efficiency of consensus protocols under harsh adversarial conditions and weak assumptions. We explore directions towards improving the two major metrics of efficiency of such protocols; i.e. their communication and round complexities. We focus on protocols operating in a synchronous communication network, and show how to achieve efficiency of either rounds or communication under different assumptions, against weakly adaptive adversaries with high corruption threshold. We will construct i) (Parallel) Broadcast protocols with improved state of the art communication, ii) the first Broadcast protocol with sublinear rounds without trusted setup, and iii) the first Deterministic Byzantine Agreement protocol with adaptive O(n·f) communication
Der griechische Gelehrte Georgios Zachariadis und sein Beitrag zum slawischen Schrifttum im 19. Jahrhundert
No full textAmong the Greek scholars who lived during the 19th century in the north-eastern Balkans, and also in Central Europe, and by their work contributed to the spiritual development of the Balkan Slavs, pride of place must be given to Georgios Zachariadis. Unfortunately, however, no detailed monograph on Zachariadis exists. On this account the problems that arise concerning the life and activities of this Greek scholar are still many and varied. In his study the author tries to fill one part of this lacuna. At the beginning of the work the following are examined, on the basis of new historical evidence: the date and place of Georgios Zachariadis’ birth, his studies and tenure as teacher in the Greek school at Zemun, the Serbian school at Šabac, and the Greek school in Vienna. The author continues his study by analyzing the various works of Zachariadis, which are written on Old Church^Slavonic, and the translations this Greek scholar made from Greek into Old Church Slavonic. Finally, the extent of Georgios Zachariadis’ contribution to Slavonic letters is made clear
The political program of Hellenism in Turkey
No full textTitle: Tό πoλιτικόν πρόγραμμα τοῦ Έλληνισμοῦ έν Tουρκία (The political program of Hellenism in Turkey) Originally published: as a leaflet in Istanbul, 1912 Language: GreekThe excerpts used are from the original which can be found at the ‘Ion Dragoumis archive’ in the Gennadion Library in Athens, pp. 7–9, 11–13, 24–25. About the author Georgios Boussios [1876, Grevena (Ottoman Macedonia) – 1929, Athens]: activist, politician and journalist. He was born into a well-off family of merchants. He c..
Correction: Do chemistry and rheology follow the same laboratory ageing trends in bitumen?
No full text Correction to: Materials and Structures (2022) 55:146 https://doi.org/10.1617/s11527-022-01986-w The article “Do chemistry and rheology follow the same laboratory ageing trends in bitumen?”, written by Georgios Pipintakos, Caitlin Lommaert, Aikaterini Varveri and Wim Van den bergh, was originally published in volume 55, issue 5, ID 146 without open access. With the society's decision to grant Open Choice the copyright of the article changed in February 2023 to © The Author(s) 2022 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0. Open access funding enabled and organized by RILEM.Pavement Engineerin
Gossiping for Communication-Efficient Broadcast
No full textByzantine Broadcast is crucial for many cryptographic pro- tocols such as secret sharing, multiparty computation and blockchain consensus. In this paper we apply gossiping (propagating a message by sending to a few random parties who in turn do the same, until the mes- sage is delivered) and propose new communication-efficient protocols, under dishonest majority, for Single-Sender Broadcast (BC) and Parallel Broadcast (PBC), improving the state-of-the-art in several ways.
As our first warm-up result, we give a randomized protocol for BC which achieves O(n^2κ^2) communication complexity from plain public key setup assumptions. This is the first protocol with subcubic communication in this setting, but does so only against static adversaries.
Using some ideas from our BC protocol, we then move to our central con- tribution and present two protocols for PBC that are secure against adap- tive adversaries. To the best of our knowledge we are the first to study PBC specifically: All previous approaches for parallel BC (PBC) naively run n instances of single-sender Broadcast, increasing the communication complexity by an undesirable factor of n. Our insight of avoiding black- box invocations of BC is particularly crucial for achieving our asymptotic improvements. In particular:
1. Our first PBC protocol achieves O(n^3κ^2) communication complexity and relies only on plain public key setup assumptions.
2. Our second PBC protocol uses trusted setup and achieves nearly optimal communication complexity O(n^2κ^4).
Both PBC protocols yield an almost linear improvement over the best known solutions involving n parallel invocations of the respective BC protocols such as those of Dolev and Strong (SIAM Journal on Comput- ing, 1983) and Chan et al. (Public Key Cryptography, 2020). Central to our PBC protocols is a new problem that we define and solve, that we call “Converge”. In Converge, parties must run an adaptively-secure and efficient protocol such that by the end of the protocol, the honest parties that remain possess a superset of the union of the inputs of the initial honest parties
The evaluation of the effect of PAMAM dendrimers in the solubility of lmiquimod
No full textCharles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Consultant: Eleni Panoutsopoulou Author: Mgr. Thu Thao Truongová Title of the thesis: The evaluation of the effect of PAMAM dendrimers in the solubility of Imiquimod Dendrimers are highly branched polymeric compounds with defined properties. They are used as a nanoparticle delivery system, however concurrently they have significant potential in enhancing the solubility of poorly water soluble drugs. Dendrimers work as drug carriers either by encapsulating the drug in their branched internal structure or they create interactions with the drug in the outer layer via terminal functional groups. The aim of this work was to evaluate the effect of polyamidoamine (PAMAM) dendrimers on the solubility of the hydrophobic drug imiquimod. Solutions of zero, first, second and third generation dendrimers were prepared at six different concentrations. During the experiment, the pH of the solutions was measured before and after addition of excess amount of imiquimod. Subsequently, analysis was performed by high-performance liquid chromatography. The measured results show that the first generation of PAMAM dendrimers is able to increase the solubility of imiquimod in...C2-Internal Abstrakt Univerzita Karlova, Farmaceutická fakulta v Hradci Králové Katedra Farmaceutické technologie Školitel: Dr. Georgios Paraskevopoulos, Ph.D. Konzultant: Eleni Panoutsopoulou Autor: Mgr. Thu Thao Truongová Název rigorózní práce: Hodnocení účinku PAMAM dendrimerů na rozpustnost imiquimodu Dendrimery jsou velmi rozvětvené polymerické sloučeniny s definovanými vlastnostmi. Používají se jako nanočásticový distribuční systém, zároveň však mají významný potenciál v oblasti zvyšování rozpustnosti ve vodě špatně rozpustných léčiv. Dendrimery fungují jako nosiče léčiva buď na principu enkapsulace molekuly léčiva ve své rozvětvené vnitřní struktuře nebo vytvářejí interakce s léčivem ve vnější vrstvě skrze terminální funkční skupiny. Cílem této práce bylo zhodnotit účinek polyamidoaminových (PAMAM) dendrimerů na rozpustnost hydrofobního léčiva imiquimod. Postupně byly připraveny roztoky dendrimerů nulté, první, druhé a třetí generace v šesti různých koncentracích. Během experimentu se měřilo pH roztoků před a po přidání nadbytečného množství imiquimodu. Následně byla provedena analýza vysokoúčinnou kapalinovou chromatografií. Z naměřených výsledků použitých generací PAMAM dendrimerů vyplývá, že první generace těchto dendrimerů dokázala nejvíce zvýšit rozpustnost imiquimodu ve vodném prostředí. Do...Department of Pharmaceutical TechnologyKatedra farmaceutické technologieFaculty of Pharmacy in Hradec KrálovéFarmaceutická fakulta v Hradci Králov
Effect of PAMAM dendrimers on the solubility and the skin permeation of flufenamic acid
No full textUniverzita Karlova, Farmaceutická fakulta v Hradci Králové Katedra Farmaceutické technologie Školitel: Dr. Georgios Paraskevopoulos, Ph.D. Autor: Lenka Novotná Název diplomové práce: Vliv PAMAM dendrimerů na rozpustnost a kožní permeaci kyseliny flufenamové Kyselinu flufenamovou (FFA) patří do skupiny nesteroidních antiflogistik. Léčiva ze skupiny nesteroidních antiflogistik jsou nejhojněji užívané léky na celém světě. Škála použití je velmi rozsáhlá. Účinek léčiv je protizánětlivý, proti bolesti a teplotě. Problém jejich použití, zejména perorálně, tkví ve velkém množství nežádoucích účinků. Pro snížení výskytu nežádoucích účinků lze FFA podávat v lokální formě. Přestup látek přes kožní bariéru je obtížný. Látky musí splňovat určitá kritéria, aby molekuly byly schopné penetrovat přes hydrofilní a zároveň hydrofóbní část lamelární lipidové multivrstvy obsažené v části epidermis. Pro zlepšení rozpustnosti FFA ve vodě bylo využito výhodných vlastností poly(amidoaminových) (PAMAM) dendrimerů. PAMAM dendrimery jsou sférické makromolekuly s velmi dobře organizovanou strukturou. Fungují i jako akceleranty kožní permeace neboli kožní enhancery. Skupina těchto pomocných látek přechodně snižuje propustnost kožní bariéry a usnadňuje transdermální podání léčiv. Mezi další výhodné vlastnosti patří výborná...Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Author: Lenka Novotná Title of the thesis: Flufenamic acid (FFA) belongs to the group of non-steroidal anti-inflammatory drugs. Medicines from the group of non-steroidal anti-inflammatory drugs are the most widely used drugs worldwide. The range of uses is very extensive. The effect of the drugs is anti- inflammatory, they also serve against pain and fever. The problem with their use, especially orally, lies in the large number of side effects. To reduce the incidence of adverse effects, FFA can be administered topically. The transfer of substances through the skin barrier is demanding. The substances must meet certain criteria so that the molecules are able to penetrate through the hydrophilic and at the same time hydrophobic part of the lamellar lipid multilayer contained in the epidermis. To improve the solubility of FFA in water, we used the advantageous properties of poly(amidoamine) (PAMAM) dendrimers. PAMAM dendrimers are spherical macromolecules with a very well-organized structure. They work well as skin permeation accelerators or skin enhancers. A group of these excipients temporarily reduces the skin barrier and facilitates the transdermal...Department of Pharmaceutical TechnologyKatedra farmaceutické technologieFarmaceutická fakulta v Hradci KrálovéFaculty of Pharmacy in Hradec Králov
Effect of selected imidazolium ionic liquids on the permeability of human skin during their co-application with model compounds
No full textUniverzita Karlova, Farmaceutická fakulta v Hradci Králové Katedra Farmaceutické technologie Školitel: Dr. Georgios Paraskevopoulos, Ph.D. Autor: Denisa Trávníčková Název diplomové práce: Vliv vybraných imidazoliových iontových kapalin na permeabilitu lidské kůže při jejich ko-aplikaci s modelovými sloučeninami Transdermální aplikace je vzhledem ke snadné aplikaci, vyhnutí se first - pass efektu a velkému povrchu kůže vhodná cesta podání léčivé látky. Hlavní bariérou, která omezuje přístup většiny látek do hlubších vrstev kůže a do systémové cirkulace je stratum corneum. Permeaci léčiv kůži navíc ovlivňuje řada faktorů, zejména fyzikálně-chemické vlastnosti látky. Struktura a funkce SC je zásadní pro udržení kožní bariéry a nalézt způsob k překonání bariérových vlastností kůže, který by nepoškodil kůži, je obtížné. Použití iontových kapalin jako enhancerů kožní penetrace představuje nový směr ve vývoji dermatologických a farmaceutických přípravků. Struktura iontových kapalin umožňuje nespočetnou kombinaci kationtů a aniontů, které by teoreticky mohly vést k syntéze iontových kapalin s požadovanou vlastností či aplikací. Tato práce přispívá k pochopení vlivu dvou imidazolových iontových kapalin na permeační profil modelových látek - theofylinu a sodné soli diklofenaku, při aplikaci na lidskou kůži...Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Supervisor: Dr. Georgios Paraskevopoulos, Ph.D. Author: Denisa Trávníčková Title of the thesis: Effect of selected imidazolium ionic liquids on the permeability of human skin during their co-application with model compounds Transdermal application is due to the ease of application, avoiding the first-pass effect and the large surface area of the skin make it a suitable route of administration. The stratum corneum is the main barrier that limits the access of most substances to the deeper layers of the skin and to the systemic circulation. In addition, the permeation of drugs through the skin is influenced by a number of factors, particularly the physicochemical properties of the substance. The structure and function of the SC is critical to the maintenance of the skin barrier, and finding a way to overcome the barrier properties of the skin that does not damage the skin is difficult. The use of ionic liquids as skin penetration enhancers represents a new direction in the development of dermatological and pharmaceutical products. The structure of ionic liquids allows for a myriad of combinations of cations and anions that could theoretically lead to the synthesis of ionic liquids with desired properties...Department of Pharmaceutical TechnologyKatedra farmaceutické technologieFarmaceutická fakulta v Hradci KrálovéFaculty of Pharmacy in Hradec Králov
- …
