Inability of the entropy vector method to certify nonclassicality in linelike causal structures

Bell's theorem shows that our intuitive understanding of causation must be overturned in light of quantum correlations. Nevertheless, quantum mechanics does not permit signalling and hence a notion of cause remains. Understanding this notion is not only important at a fundamental level, but also for technological applications such as key distribution and randomness expansion. It has recently been shown that a useful way to decide which classical causal structures could give rise to a given set of correlations is to use entropy vectors. These are vectors whose components are the entropies of all subsets of the observed variables in the causal structure. The entropy vector method employs causal relationships among the variables to restrict the set of possible entropy vectors. Here, we consider whether the same approach can lead to useful certificates of non-classicality within a given causal structure. Surprisingly, we find that for a family of causal structures that include the usual bipartite Bell structure they do not. For all members of this family, no function of the entropies of the observed variables gives such a certificate, in spite of the existence of nonclassical correlations. It is therefore necessary to look beyond entropy vectors to understand cause from a quantum perspective.Comment: 5 pages + appendix, v2: added references, v3: new title, added journal referenc

Secondary user relations in emerging mobile computing environments

Mobile technologies are enabling access to information in diverse environ.ments, and are exposing a wider group of individuals to said technology. Therefore, this paper proposes that a wider view of user relations than is usually considered in information systems research is required. Specifically, we examine the potential effects of emerging mobile technologies on end-­‐user relations with a focus on the ‘secondary user’, those who are not intended to interact directly with the technology but are intended consumers of the technology’s output. For illustration, we draw on a study of a U.K. regional Fire and Rescue Service and deconstruct mobile technology use at Fire Service incidents. Our findings provide insights, which suggest that, because of the nature of mobile technologies and their context of use, secondary user relations in such emerging mobile environments are important and need further exploration

Axiomatic relation between thermodynamic and information-theoretic entropies

Thermodynamic entropy, as defined by Clausius, characterizes macroscopic observations of a system based on phenomenological quantities such as temperature and heat. In contrast, information-theoretic entropy, introduced by Shannon, is a measure of uncertainty. In this Letter, we connect these two notions of entropy, using an axiomatic framework for thermodynamics [Lieb, Yngvason, Proc. Roy. Soc.(2013)]. In particular, we obtain a direct relation between the Clausius entropy and the Shannon entropy, or its generalisation to quantum systems, the von Neumann entropy. More generally, we find that entropy measures relevant in non-equilibrium thermodynamics correspond to entropies used in one-shot information theory

Smooth Entropy in Axiomatic Thermodynamics

Thermodynamics can be formulated in either of two approaches, the phenomenological approach, which refers to the macroscopic properties of systems, and the statistical approach, which describes systems in terms of their microscopic constituents. We establish a connection between these two approaches by means of a new axiomatic framework that can take errors and imprecisions into account. This link extends to systems of arbitrary sizes including very small systems, for which the treatment of imprecisions is pertinent to any realistic situation. Based on this, we identify the quantities that characterise whether certain thermodynamic processes are possible with entropy measures from information theory. In the error-tolerant case, these entropies are so-called smooth min and max entropies. Our considerations further show that in an appropriate macroscopic limit there is a single entropy measure that characterises which state transformations are possible. In the case of many independent copies of a system (the so-called i.i.d. regime), the relevant quantity is the von Neumann entropy. Transformations among microcanonical states are characterised by the Boltzmann entropy

Locative Media and Sociability:Using Location-Based Social Networks to Coordinate Everyday Life

Foursquare was a mobile social networking application that enabled people to share location with friends in the form of “check-ins.” The visualization of surrounding known social connections as well as unknown others has the potential to impact how people coordinate social encounters and forge new social ties. While many studies have explored mobile phones and sociability, there is a lack of empirical research examining location-based social network’s (LSBNs) from a sociability perspective. Drawing on a dataset of original qualitative research with a range of Foursquare users, the paper examines the application in the context of social coordination and sociability in three ways. First, the paper explores if Foursquare is used to organize certain social encounters, and if so, why. Second, the paper examines the visualization of surrounding social connections and whether this leads to “serendipitous encounters.” Lastly, the paper examines whether the use of Foursquare can produce new social relationships

Management of Lost Atherectomy Devices in the Coronary Arteries

\ua9 2025 The Author(s). Catheterization and Cardiovascular Interventions published by Wiley Periodicals LLC. Rotational and orbital atherectomy are important tools to treat calcific coronary disease. Entrapment of an atherectomy device, that is, rotational atherectomy burr or orbital atherectomy crown, is a serious complication during atherectomy. Loss of an atherectomy device is a more challenging complication that usually follows device entrapment. Although uncommon, given the increased adoption of atherectomy, it is important for interventional cardiologist to understand the mechanisms and principles for prevention and management of lost atherectomy devices. Given the paucity of reported cases, there is no clear consensus or defined approach as to how this complication is best managed. The current recommendations for burr/crown entrapment are generally to remove everything from the coronary vasculature and range from different percutaneous strategies and ultimately cardiac surgery. Conservative treatment with leaving the burr within the coronary vasculature has not been recommended. This article serves to review and provide a contemporary update on the management of lost atherectomy devices in the coronary arteries. We review the management and techniques centered around cases of lost atherectomy devices including a unique cohort of patients with lost burrs/crowns that were left in the coronary arteries. Finally, we provide an algorithmic approach to the contemporary management of lost atherectomy devices, incorporating a conservative strategy arm, and discuss situations where this may be considered

Influencia de los cambios redox del receptor de rianodina (RyR2) sobre las arritmias cardíacas de reperfusión

El funcionamiento anormal del canal liberador de Ca2+, del retículo sarcoplasmático cardíaco o receptor de rianodina (RyR2), es reconocido como un factor importante en la patogénesis de las arritmias cardíacas. Cuando el miocardio es sometido a un período breve de isquemia seguido de reperfusión, se produce una alteración en la homeostasis del Ca2+ intracelular y un aumento del estrés oxidativo, que coinciden temporalmente con la aparición de arritmias.Facultad de Ciencias Médica

Influencia de los cambios redox del receptor de rianodina (RyR2) sobre las arritmias cardíacas de reperfusión

El funcionamiento anormal del canal liberador de Ca2+, del retículo sarcoplasmático cardíaco o receptor de rianodina (RyR2), es reconocido como un factor importante en la patogénesis de las arritmias cardíacas. Cuando el miocardio es sometido a un período breve de isquemia seguido de reperfusión, se produce una alteración en la homeostasis del Ca2+ intracelular y un aumento del estrés oxidativo, que coinciden temporalmente con la aparición de arritmias.Facultad de Ciencias Médica