418 research outputs found
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
Exoteric effects at nanoscopic interfaces - Uncommon negative compressibility of nanoporous materials and unexpected cavitation at liquid/liquid interfaces
This PhD thesis is devoted to the investigation of some peculiar effects happening at nanoscopic interfaces between immiscible liquids or liquids and solids via molecular dynamics simulations. The study of the properties of interfaces at a nanoscopic scale is driven by the promise of many interesting technological applications, including: a novel technology for developing both eco-friendly energy storage devices in the form of mechanical batteries, as well as energy dissipation systems and, in particular, shock absorbers for the automotive market; biomedical applications related to cavitation, such as High-Intensity Focused Ultrasound (HIFU) ablation of cancer tissues and localised drug delivery, and many more. The kinetics of phenomena taking places at these scales is typically determined by large free-energy barriers separating the initial and final states, and even intermediate metastable states, when they are present. Because of such barriers, the phenomena we are interested in are "rare events", i.e. the system attempts the crossing of the barrier(s) many times before finally succeeding when an energy fluctuation makes it possible. At the same time, the magnitude of the barrier is determined by the energetics and dynamics of atoms, which forces us to model the system by taking into account both the femtosecond atomistic timescale and the timescale of the relevant phenomena, typically exceeding the former by several orders of magnitude. These longer timescales are inaccessible to standard molecular dynamics, so, in order to tackle this issue, advanced MD techniques need to be employed.
The thesis is divided into two parts, corresponding to the main lines of research investigated, which are (I) the interfaces between water and complex nanoporous solids, and (II) planar solid-liquid and liquid-liquid interfaces. Anticipating some results, atomistic simulations helped uncovering the microscopic mechanism behind the (incredibly rare!) giant negative compressibility exhibited by the ZIF-8 metal organic framework (MOF) upon water intrusion. Molecular dynamics simulations also supported experimental results showing how it is possible to change the intermediate intrusion-extrusion performance of ZIF-8 by changing its grain morphology and arrangement, from a fine powder to compact monolith. Free-energy MD calculations allowed to explain the exceptional stability of surface nanobubbles in water, at undersaturated conditions, on a surprisingly wide variety of substrates, characterized by disparate hydrophobicities and gas affinities; and yet, how they catastrophically destabilize in organic solvents. Finally, through simulations, some light was shed upon the working mechanism behind the novelly discovered phenomenon of how the interface between two immiscible liquids can act as a nucleation site for cavitation
The European Experience: A Multi-Perspective History of Modern Europe, 1500–2000
The European Experience brings together the expertise of nearly a hundred historians from eight European universities to internationalise and diversify the study of modern European history, exploring a grand sweep of time from 1500 to 2000. Offering a valuable corrective to the Anglocentric narratives of previous English-language textbooks, scholars from all over Europe have pooled their knowledge on comparative themes such as identities, cultural encounters, power and citizenship, and economic development to reflect the complexity and heterogeneous nature of the European experience. Rather than another grand narrative, the international author teams offer a multifaceted and rich perspective on the history of the continent of the past 500 years. Each major theme is dissected through three chronological sub-chapters, revealing how major social, political and historical trends manifested themselves in different European settings during the early modern (1500–1800), modern (1800–1900) and contemporary period (1900–2000). This resource is of utmost relevance to today’s history students in the light of ongoing internationalisation strategies for higher education curricula, as it delivers one of the first multi-perspective and truly ‘European’ analyses of the continent’s past. Beyond the provision of historical content, this textbook equips students with the intellectual tools to interrogate prevailing accounts of European history, and enables them to seek out additional perspectives in a bid to further enrich the discipline
LIPIcs, Volume 261, ICALP 2023, Complete Volume
LIPIcs, Volume 261, ICALP 2023, Complete Volum
The Computational Power of Distributed Shared-Memory Models with Bounded-Size Registers
The celebrated Asynchronous Computability Theorem of Herlihy and Shavit (STOC
1993 and STOC 1994) provided a topological characterization of the tasks that
are solvable in a distributed system where processes are communicating by
writing and reading shared registers, and where any number of processes can
fail by crashing. However, this characterization assumes the use of
full-information protocols, that is, protocols in which each time any of the
processes writes in the shared memory, it communicates everything it learned
since the beginning of the execution. Thus, the characterization implicitly
assumes that each register in the shared memory is of unbounded size. Whether
unbounded size registers are unavoidable for the model of computation to be
universal is the central question studied in this paper. Specifically, is any
task that is solvable using unbounded registers solvable using registers of
bounded size? More generally, when at most processes can crash, is the
model with bounded size registers universal? These are the questions answered
in this paper
The Time Complexity of Consensus Under Oblivious Message Adversaries
We study the problem of solving consensus in synchronous directed dynamic networks, in which communication is controlled by an oblivious message adversary that picks the communication graph to be used in a round from a fixed set of graphs ? arbitrarily. In this fundamental model, determining consensus solvability and designing efficient consensus algorithms is surprisingly difficult. Enabled by a decision procedure that is derived from a well-established previous consensus solvability characterization for a given set ?, we study, for the first time, the time complexity of solving consensus in this model: We provide both upper and lower bounds for this time complexity, and also relate it to the number of iterations required by the decision procedure. Among other results, we find that reaching consensus under an oblivious message adversary can take exponentially longer than both deciding consensus solvability and broadcasting the input value of some unknown process to all other processes
Covid Conspiracy Theories in Global Perspective
Covid Conspiracy Theories in Global Perspective examines how conspiracy theories and related forms of misinformation and disinformation about the Covid-19 pandemic have circulated widely around the world.
Covid conspiracy theories have attracted considerable attention from researchers, journalists, and politicians, not least because conspiracy beliefs have the potential to negatively affect adherence to public health measures. While most of this focus has been on the United States and Western Europe, this collection provides a unique global perspective on the emergence and development of conspiracy theories through a series of case studies. The chapters have been commissioned by recognized experts on area studies and conspiracy theories.
The chapters present case studies on how Covid conspiracism has played out (some focused on a single country, others on regions), using a range of methods from a variety of disciplinary perspectives, including history, politics, sociology, anthropology, and psychology. Collectively, the authors reveal that, although there are many narratives that have spread virally, they have been adapted for different uses and take on different meanings in local contexts.
This volume makes an important contribution to the rapidly expanding field of academic conspiracy theory studies, as well as being of interest to those working in the media, regulatory agencies, and civil society organizations, who seek to better understand the problem of how and why conspiracy theories spread
Formal Methods for Autonomous Systems
Formal methods refer to rigorous, mathematical approaches to system
development and have played a key role in establishing the correctness of
safety-critical systems. The main building blocks of formal methods are models
and specifications, which are analogous to behaviors and requirements in system
design and give us the means to verify and synthesize system behaviors with
formal guarantees.
This monograph provides a survey of the current state of the art on
applications of formal methods in the autonomous systems domain. We consider
correct-by-construction synthesis under various formulations, including closed
systems, reactive, and probabilistic settings. Beyond synthesizing systems in
known environments, we address the concept of uncertainty and bound the
behavior of systems that employ learning using formal methods. Further, we
examine the synthesis of systems with monitoring, a mitigation technique for
ensuring that once a system deviates from expected behavior, it knows a way of
returning to normalcy. We also show how to overcome some limitations of formal
methods themselves with learning. We conclude with future directions for formal
methods in reinforcement learning, uncertainty, privacy, explainability of
formal methods, and regulation and certification
Fundamentals
Volume 1 establishes the foundations of this new field. It goes through all the steps from data collection, their summary and clustering, to different aspects of resource-aware learning, i.e., hardware, memory, energy, and communication awareness. Machine learning methods are inspected with respect to resource requirements and how to enhance scalability on diverse computing architectures ranging from embedded systems to large computing clusters
Towards Spatial Porosity: Revisiting the Contemporary American Campus Novel
Η παρούσα διατριβή αποτελεί μέρος ενός ανοιχτού διαλόγου στις Ανθρωπιστικές Επιστήμες για τη μελέτη του χώρου ως διεπιστημονικό ζήτημα. Συγκεκριμένα, το παρόν πόνημα ασχολείται με τη λογοτεχνική παρουσία του Αμερικανικού Ακαδημαϊκού Μυθιστορήματος στη σύγχρονη Αμερικανική Λογοτεχνία. Υποστηρίζω ότι η Αμερικανική Πανεπιστημιούπολη στα μυθιστορήματα που εξετάζω δε συνάδει με το στερεότυπο του αποκομμένου από την κοινωνική πραγματικότητα χώρου όπου η υψηλή διανόηση αρνείται να ανοίξει δίοδο επικοινωνίας με τον έξω κόσμο. Αντιθέτως, πιστεύω πως η Αμερικανική Πανεπιστημιούπολη παρουσιάζεται σαν ένα πορώδες οικοδόμημα το οποίο επιτρέπει την αλληλεπίδραση κοινωνίας-πανεπιστημίου και καταγράφει τις κοινωνικοπολιτικές εντάσεις κάθε ιστορικής περιόδου. Η αμερικανική πανεπιστημιούπολη, στα μυθιστορήματα αυτά, βρίσκεται σε συνεχή διαπραγμάτευση με τον κόσμο που βρίσκεται πέρα από τα τείχη της ακαδημαϊκής κοινότητας και χρησιμεύει ως φωλιά για νέες ιδέες που βρίσκουν το δρόμο τους πίσω στην κοινωνία. Η αναπαράσταση της αμερικανικής πανεπιστημιούπολης στη λογοτεχνία υπογραμμίζει το γεγονός ότι παρόλο που οι χωρικές πρακτικές της πανεπιστημιούπολης εμποτίζονται από την κυρίαρχη ιδεολογία, οι χαρακτήρες που κινούνται σε αυτόν τον χώρο γράφουν τις δικές τους ιστορίες στο χώρο, επιτρέποντας έτσι μια επανεξέταση της ακαδημαϊκής κοινότητας που απομακρύνεται από την στερεοτυπική της εικόνα. Αυτή η συνεχής αλληλεπίδραση του πανεπιστημιακού χώρου με την κοινωνία καθίσταται εφικτή μέσω της διαπερατότητας των πανεπιστημιακών τειχών, η οποία αναλύεται στην παρούσα διατριβή μέσω της αναλογίας της με τη διαπερατότητα της κυτταρικής μεμβράνης, μία αναλογία που ακολουθεί ο Richard Sennett για να μιλήσει για την ανοιχτή, πορώδη πόλη. Μεθοδολογικά η διατριβή κινείται στο χώρο της Λογοτεχνίας αλλά και της Αρχιτεκτονικής Θεωρίας. Ειδικότερα, εκτός από τη θεωρία του Sennett για την πορώδη πόλη μεταξύ άλλων χρησιμοποιώ τη θεωρία των Michel Foucault, Michel de Certeau και Gaston Bachelard. Ο διεπιστημονικός χαρακτήρας αυτής της έρευνας υπογραμμίζει τη σχέση μεταξύ της λογοτεχνικής παραγωγής του Ακαδημαϊκού Μυθιστορήματος και ζητημάτων χωροταξίας και εξουσίας σε αυτό το εξαιρετικά ξεχωριστό αμερικανικό μέρος, την Πανεπιστημιούπολη.This dissertation joins a vibrant conversation in the humanities concerning the study of space as an interdisciplinary endeavor. In particular, my work explores the literary presence of the American University Campus in contemporary American literature. Collectively, the novels in this study articulate the fact that the American Campus—its space, its architecture, the relationships developed within it but also those with the surrounding community—not only registers but also produces social dynamics. I contend that the American Campus in the novels examined is not an Ivory Tower that stands aside from society but a porous space that allows interaction with society and promptly registers the tensions that affect each era. In literature and architecture porosity in space has been likened to porosity in nature with many sociologists and architects borrowing from Biology and contending that porosity is a critical feature for the viability of an organism since it functions at once as a boundary that keeps the identity of the organism and as a sieve that helps in the interaction with the surrounding environment. Expanding on this analogy I will be analyzing the porous quality of campus space as it is represented in the contemporary American campus novel. The American campus is in constant negotiation with the world that lies beyond the walls of academia, and it serves as a nest for new ideas that find their way back to society. The representation of the American Campus in literature underlines the fact that even though campus spatial practices are imbued by the dominant ideology, the characters moving in this space write their own spatial stories, thus allowing for a reconsideration of academia that moves away from its traditional image of the unyielding Ivory Tower. Methodologically, Towards the Porous Campus: The Contemporary American Campus Novel moves through socio-spatial situations and fictional Campuses in an interdisciplinary manner borrowing from architecture and theories of space. More specifically among others I am using Michel Foucault, Michel de Certeau, Gaston Bachelard and Richard Sennett’s theory of the porous city. The interdisciplinary nature of this inquiry highlights the interrelationship between the literary production of the Campus Novel and issues of spatiality and power in this highly distinctive American place, the Campus
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