Particle dynamics in a class of 2-dimensional gravity theories

We provide a method to determine the motion of a classical massive particle in a background geometry of 2-dimensional gravity theories, for which the Birkhoff theorem holds. In particular, we get the particle trajectory in a continuous class of 2-dimensional dilaton gravity theories that includes the Callan-Giddings-Harvey-Strominger (CGHS) model, the Jackiw-Teitelboim (JT) model, and the $d$-dimensional $s$-wave Einstein gravity. The explicit trajectory expressions for these theories are given along with the discussions on the results.Comment: 15 pages, LaTeX. The deletion of the repeated portion of the abstract and the proper line wrapping of the tex file. No other change

Conserved Quasilocal Quantities and General Covariant Theories in Two Dimensions

General matterless--theories in 1+1 dimensions include dilaton gravity, Yang--Mills theory as well as non--Einsteinian gravity with dynamical torsion and higher power gravity, and even models of spherically symmetric d = 4 General Relativity. Their recent identification as special cases of 'Poisson--sigma--models' with simple general solution in an arbitrary gauge, allows a comprehensive discussion of the relation between the known absolutely conserved quantities in all those cases and Noether charges, resp. notions of quasilocal 'energy--momentum'. In contrast to Noether like quantities, quasilocal energy definitions require some sort of 'asymptotics' to allow an interpretation as a (gauge--independent) observable. Dilaton gravitation, although a little different in detail, shares this property with the other cases. We also present a simple generalization of the absolute conservation law for the case of interactions with matter of any type.Comment: 21 pages, LaTeX-fil

National identity predicts public health support during a global pandemic

Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = −0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics.publishedVersio

G-DPS:A Game-theoretical Decision-making Framework for Physical Surveillance Games

Critical infrastructure protection becomes increasingly a major concern in governments and industries. Besides the increasing rates of cyber-crime, recent terrorist attacks bring critical infrastructure into a severer environment. Many critical infrastructures, in particular those operating large industry complexes, incorporate some kind of physical surveillance technologies to secure their premises. Surveillance systems, such as access control and malicious behavior detection, have been long used for perimeter security as a first line of defense. Traditional perimeter security solutions typically monitor the outer boundary structures and lines, thus ignoring threats from the inside. Moreover, the deterrent effect of surveillance systems like Closed Circuit Television (CCTV) becomes considerably less important due to the inflexibility induced by their fixed installations. Hence, an infrastructure’s surveillance policy is more predictable and a potential adversary has a better opportunity to observe and bypass it subsequently. Therefore, it is important to maintain situational awareness within such environments so that potential intruders can still be detected. Regardless of whether personnel (e.g., security guards, etc.) or technical solutions (e.g., cameras, etc.) are applied, such surveillance systems have an imperfect detection rate, leaving an intruder with the potential to cause some damage to the infrastructure. Hence, the core problem is to find an optimal application of the surveillance technology at hand to minimize such a potential damage. This problem already has a natural reflection in game theory known as cops-and-robbers game but current models always assume a deterministic outcome of the gameplay. In this work, we present a decision-making framework, which assesses possible choices and alternatives towards finding an optimal surveillance configurations and hence minimizing addressed risks. The decision is made by means of a game-theoretic model for optimizing physical surveillance systems and minimizing the potential damage caused by an intruder with respect to the imperfect detection rates of surveillance technology. With our approach, we have the advantage of using categorical (or continuous) distributions instead of a single numerical value to capture the uncertainty in describing the potential damage of an intruder. This gives us the opportunity to model the imperfection of surveillance systems and to optimize over large collections of empirical or simulated data without losing valuable information during the process

The rise and decline of character: humoral psychology in ancient and early modern medical theory

Humoralism, the view that the human body is composed of a limited number of elementary fluids, is one of the most characteristic aspects of ancient medicine. The psychological dimension of humoral theory in the ancient world has thus far received a relatively small amount of scholarly attention. Medical psychology in the ancient world can only be correctly understood by relating it to psychological thought in other fields, such as ethics and rhetoric. The concept that ties these various domains together is character (êthos), which involves a view of human beings focused on clearly distinguishable psychological types that can be recognized on the basis of external signs. Psychological ideas based on humoral theory remained influential well into the early modern period. Yet, in 17th-century medicine and philosophy, humoral physiology and psychology started to lose ground to other theoretical perspectives on the mind and its relation to the body. This decline of humoralist medical psychology can be related to a broader reorientation of psychological thought in which the traditional concept of character lost its central position. Instead of the focus on types and stable character traits, a perspective emerged that was primarily concerned with individuality and transient passions