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2022 ◽  
Vol 183 (1-2) ◽  
pp. 97-123
Author(s):  
Didier Lime ◽  
Olivier H. Roux ◽  
Charlotte Seidner

We investigate the problem of parameter synthesis for time Petri nets with a cost variable that evolves both continuously with time, and discretely when firing transitions. More precisely, parameters are rational symbolic constants used for time constraints on the firing of transitions and we want to synthesise all their values such that some marking is reachable, with a cost that is either minimal or simply less than a given bound. We first prove that the mere existence of values for the parameters such that the latter property holds is undecidable. We nonetheless provide symbolic semi-algorithms for the two synthesis problems and we prove them both sound and complete when they terminate. We also show how to modify them for the case when parameter values are integers. Finally, we prove that these modified versions terminate if parameters are bounded. While this is to be expected since there are now only a finite number of possible parameter values, our algorithms are symbolic and thus avoid an explicit enumeration of all those values. Furthermore, the results are symbolic constraints representing finite unions of convex polyhedra that are easily amenable to further analysis through linear programming. We finally report on the implementation of the approach in Romeo, a software tool for the analysis of time Petri nets.


2021 ◽  
Vol 118 (49) ◽  
pp. e2113141118
Author(s):  
Chenghan Li ◽  
Gregory A. Voth

Water-assisted proton transport through confined spaces influences many phenomena in biomolecular and nanomaterial systems. In such cases, the water molecules that fluctuate in the confined pathways provide the environment and the medium for the hydrated excess proton migration via Grotthuss shuttling. However, a definitive collective variable (CV) that accurately couples the hydration and the connectivity of the proton wire with the proton translocation has remained elusive. To address this important challenge—and thus to define a quantitative paradigm for facile proton transport in confined spaces—a CV is derived in this work from graph theory, which is verified to accurately describe water wire formation and breakage coupled to the proton translocation in carbon nanotubes and the Cl−/H+ antiporter protein, ClC-ec1. Significant alterations in the conformations and thermodynamics of water wires are uncovered after introducing an excess proton into them. Large barriers in the proton translocation free-energy profiles are found when water wires are defined to be disconnected according to the new CV, even though the pertinent confined space is still reasonably well hydrated and—by the simple measure of the mere existence of a water structure—the proton transport would have been predicted to be facile via that oversimplified measure. In this paradigm, however, the simple presence of water is not sufficient for inferring proton translocation, since an excess proton itself is able to drive hydration, and additionally, the water molecules themselves must be adequately connected to facilitate any successful proton transport.


2021 ◽  
Vol 41 (3) ◽  
pp. 404-412
Author(s):  
Orit Bashkin

Abstract This essay considers accounts of the Dreyfus Affair published in the newspaper Thamarat al-Funun (founded 1875) during 1898 to demonstrate how Arab writers addressed the rights of minorities in Europe and examined failed emancipatory projects. Writing about the Dreyfus Affair allowed intellectuals in the Levant to reverse the power relationship between themselves and Europe and to comment on the kinds of politics that would ensure the equality before the law of the Jewish minority in Europe. These debates further illustrate that even before the shift to electoral politics in the Ottoman Empire (after 1908) and in postwar Arab nation-states, Arab writers were preoccupied with the relationship between statecraft and majority-minority relations. They argued that democratic institutions such as parliaments and courts of law were the best venues to safeguard the rights of religious communities whose mere existence was defined as a problem. Bashkin shows how Thamarat al-Funun pointed to phenomena that endangered religious communities, such as fanaticism, racism, abuse of power by the police and the military, and mob politics.


2021 ◽  
Author(s):  
Kelvin K. F. Law ◽  
Lillian Mills

Users of Exhibit 21 cannot tell whether a tax haven subsidiary is actively operating or a dormant shell company.  In this paper, we develop a new set of parsimonious measures to highlight the distinct mechanisms and tax effects of offshore sales to, as opposed to purchases from, tax haven countries, offering insights on the effects of certain types of offshoring activities on firms’ tax burdens.  Our main measure has about three times the effect of the mere existence of a haven subsidiary in explaining firms’ effective tax rates.  We detail the processes to predict the offshore activities in tax haven countries for firms without an Exhibit 21 and firms reporting no subsidiary operations in a tax haven country.  Relative to the mere mention of a tax haven subsidiary in Exhibit 21, our new measures provide a richer information set to capture different types of economic activities in tax haven countries.


2021 ◽  
Author(s):  
John R Kerr ◽  
Anne Marthe van der Bles ◽  
Claudia Schneider ◽  
Sarah Dryhurst ◽  
Vivien Chopurian ◽  
...  

A growing body of research indicates that transparent communication of statistical uncertainty around facts and figures does not undermine credibility. However, the extent to which these findings apply in the context of the COVID-19 pandemic--rife with uncertainties--is unclear. In a large international survey experiment, (Study 1; N = 10,519) we report that communicating uncertainty around COVID-19 statistics in the form of a numeric range (vs. no uncertainty) may lead to slightly lower trust in the number presented but has no impact on trust in the source of the information. We also report the minimal impact of numeric uncertainty on trust is consistent across estimates of current or future COVID-19 statistics (Study 2) and figures relating to environmental or economic research, rather than the pandemic (Study 3). Conversely, we find imprecise statements about the mere existence of uncertainty without quantification can undermine both trust in the numbers and their source--though effects vary across countries and contexts. Communicators can be transparent about statistical uncertainty without concerns about undermining perceptions of their trustworthiness, but ideally should aim to use numerical ranges rather than verbal statements.


Author(s):  
Antje Otto ◽  
Christian Göpfert ◽  
Annegret H. Thieken

AbstractCities can be severely affected by climate change. Hence, many of them have started to develop climate adaptation strategies or implement measures to help prepare for the challenges it will present. This study aims to provide an overview of climate adaptation in 104 German cities. While existing studies on adaptation tracking rely heavily on self-reported data or the mere existence of adaptation plans, we applied the broader concept of adaptation readiness, considering five factors and a total of twelve different indicators, when making our assessments. We clustered the cities depending on the contribution of these factors to the overall adaptation readiness index and grouped them according to their total score and cluster affiliations. This resulted in us identifying four groups of cities. First, a pioneering group comprises twelve (mainly big) cities with more than 500,000 inhabitants, which showed high scores for all five factors of adaptation readiness. Second, a set of 36 active cities, which follow different strategies on how to deal with climate adaptation. Third, a group of 28 cities showed considerably less activity toward climate adaptation, while a fourth set of 28 mostly small cities (with between 50,000 and 99,999 inhabitants) scored the lowest. We consider this final group to be pursuing a ‘wait-and-see’ approach. Since the city size correlates with the adaptation readiness index, we recommend policymakers introduce funding schemes that focus on supporting small cities, to help them prepare for the impact of a changing climate.


2021 ◽  
pp. 46-53
Author(s):  
Bhavya Walia ◽  
Siddhant Saggar

A medium to facilitate the exchange of value has been the sole necessity for the mere existence of currency. As the civilization moved from using metals, paper, and plastic to facilitate exchange, our requirements from a currency became refined. Some of those requirements were the prevention of counterfeiting and accountability. As the human civilization moves forward, the solution to some of the problems faced by us are discovered by humans. Cryptocurrency is a decentralized form of currency mined by computers by solving complex equations in exchange for a reward of the very same commodity. This article aims to study the major cryptocurrencies and the concept of blockchain, how they operate, how it will be affecting India, and what are the consequences of banning this form of currency. This research is carried out by evaluating white papers of Bitcoin and Ethereum (the two main cryptocurrencies of present time) along with research papers and news articles found with the help of search engines and online discussion threads.


GigaScience ◽  
2021 ◽  
Vol 10 (8) ◽  
Author(s):  
Elizabeth Levitis ◽  
Cassandra D Gould van Praag ◽  
Rémi Gau ◽  
Stephan Heunis ◽  
Elizabeth DuPre ◽  
...  

Abstract As the global health crisis unfolded, many academic conferences moved online in 2020. This move has been hailed as a positive step towards inclusivity in its attenuation of economic, physical, and legal barriers and effectively enabled many individuals from groups that have traditionally been underrepresented to join and participate. A number of studies have outlined how moving online made it possible to gather a more global community and has increased opportunities for individuals with various constraints, e.g., caregiving responsibilities. Yet, the mere existence of online conferences is no guarantee that everyone can attend and participate meaningfully. In fact, many elements of an online conference are still significant barriers to truly diverse participation: the tools used can be inaccessible for some individuals; the scheduling choices can favour some geographical locations; the set-up of the conference can provide more visibility to well-established researchers and reduce opportunities for early-career researchers. While acknowledging the benefits of an online setting, especially for individuals who have traditionally been underrepresented or excluded, we recognize that fostering social justice requires inclusivity to actively be centered in every aspect of online conference design. Here, we draw from the literature and from our own experiences to identify practices that purposefully encourage a diverse community to attend, participate in, and lead online conferences. Reflecting on how to design more inclusive online events is especially important as multiple scientific organizations have announced that they will continue offering an online version of their event when in-person conferences can resume.


2021 ◽  
Vol 1 ◽  
pp. 147
Author(s):  
Danielle Dionne ◽  
Elizabeth Coppock

This paper addresses the question of how to predict which alternatives are active in scalar implicature calculation, and the nature of this activation. It has been observed that finger implicates 'not thumb', and a Manner-based explanation for this has been proposed, predicting that if English had the simplex Latin word pollex meaning 'thumb or big toe', then finger would cease to have the implicature 'not thumb' that it has. It has also been suggested that this hypothetical pollex would have to be sufficiently colloquial in order to figure in scalar implicature calculation. This paper makes this thought experiment into a real one by using a language that behaves in exactly this way: Spanish has pulgar 'thumb' (< pollex), a non-colloquial form. We first use a fill-in-the-blank production task with both English and Spanish speakers to guage the likelihood with which a speaker will produce a given form as a way of describing a given digit. Production frequency does not perfectly track complexity, so we can then ask whether comprehension follows production frequency or complexity. We do so using a forced choice comprehension task, which reveals cross-linguistic differences in comprehension tracking production probabilities. A comparison between two RSA models -- one in which the speaker perfectly replicates our production data and a standard one in which the speaker chooses based on a standard cost/accuracy trade-off -- illustrates the fact that comprehension is much more closely tied to production probability than to the mere existence of sufficiently simple alternatives.


2021 ◽  
Author(s):  
Chenghan Li ◽  
Gregory A. Voth

Water assisted proton transport through confined spaces influences many phenomena in biomolecular and nanomaterial systems. In such cases, the water molecules that fluctuate in the confined pathways provide the environment and the medium for the hydrated excess proton migration via Grotthuss shuttling. However, a definitive collective variable (CV) that accurately couples the hydration and the connectivity of the proton wire with the proton translocation has remained elusive. To address this important challenge-and thus to define a new quantitative paradigm for facile proton transport in confined spaces-a CV is derived in this work from graph theory, which is verified to accurately describe water wire formation and breakage coupled to the proton translocation in carbon nanotubes and the Cl-/H+ antiporter protein, ClC-ec1. Significant alterations in the conformations and thermodynamics of water wires are uncovered after introducing an excess proton into them. Large barriers in the proton translocation free energy profiles are found when water wires are defined to be disconnected according to the new CV, even though the pertinent confined space is still reasonably well hydrated and-by the simple measure of the mere existence of a water structure-the proton transport would have been predicted to be facile via that oversimplified measure. In this new paradigm, however, the simple presence of water is not sufficient for inferring proton translocation since an excess proton itself is able to drive hydration and, additionally, the water molecules themselves must be adequately connected to facilitate any successful proton transport.


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