Altmann E.G.,Max Planck Institute for the Physics of Complex Systems |
Portela J.S.E.,Max Planck Institute for the Physics of Complex Systems |
Portela J.S.E.,Fraunhofer Institute for Industrial Mathematics |
Tel T.,Eotvos Lorand University
Reviews of Modern Physics | Year: 2013
There are numerous physical situations in which a hole or leak is introduced in an otherwise closed chaotic system. The leak can have a natural origin, it can mimic measurement devices, and it can also be used to reveal dynamical properties of the closed system. A unified treatment of leaking systems is provided and applications to different physical problems, in both the classical and quantum pictures, are reviewed. The treatment is based on the transient chaos theory of open systems, which is essential because real leaks have finite size and therefore estimations based on the closed system differ essentially from observations. The field of applications reviewed is very broad, ranging from planetary astronomy and hydrodynamical flows to plasma physics and quantum fidelity. The theory is expanded and adapted to the case of partial leaks (partial absorption and/or transmission) with applications to room acoustics and optical microcavities in mind. Simulations in the limaçon family of billiards illustrate the main text. Regarding billiard dynamics, it is emphasized that a correct discrete-time representation can be given only in terms of the so-called true-time maps, while traditional Poincaré maps lead to erroneous results. Perron-Frobenius-type operators are generalized so that they describe true-time maps with partial leaks. © 2013 American Physical Society.
Csaszar A.G.,Eotvos Lorand University
Wiley Interdisciplinary Reviews: Computational Molecular Science | Year: 2012
An anharmonic force field is defined as a higher-order Taylor-series expansion of the molecular potential energy surface (PES) around a reference geometry, usually chosen to be an equilibrium structure. Force field expansions provide excellent local approximations to PESs, one of the most important theoretical constructs of chemistry. This review deals principally with the definition and physical interpretation of anharmonic molecular force fields, their determination via techniques of electronic structure theory, their transformation among different rectilinear and curvilinear representations, and their utilization. Physical and technical factors leading to more precise and more accurate force fields are also discussed. © 2011 John Wiley & Sons, Ltd.
Miklosi A.,Eotvos Lorand University |
Miklosi A.,MTA ELTE Comparative Ethology Research Group |
Topal J.,Hungarian Academy of Sciences
Trends in Cognitive Sciences | Year: 2013
The traditional and relatively narrow-focused research on ape-human comparisons has recently been significantly extended by investigations of different clades of animals, including the domestic dog (Canis familiaris). Here, we provide a short overview of how the comparative investigation of canine social behaviour advances our understanding of the evolution of social skills and argue that a system-level approach to dog social cognition provides a broader view on the 'human-likeness' of canine social competence. We introduce the concept of evolutionary social competence as a collateral notion of developmental social competence. We argue that such an extended perspective on social competence provides a useful tool for conceptualising wolf-dog differences in socio-cognitive functioning, as well as for considering specific social skills not in isolation, but as a part of a system. © 2013 Elsevier Ltd.
Low P.,Eotvos Lorand University
General and Comparative Endocrinology | Year: 2011
Maintenance of cellular homeostasis influences ageing and it is determined by several factors, including efficient proteolysis of damaged proteins. The ubiquitin-proteasome system is the major protein degradation pathway in the cell. Specifically, the proteasome is responsible for clearance of abnormal, denatured or in general damaged proteins as well as for the regulated degradation of short-lived proteins. In this review the involvement of the ubiquitin-proteasome pathway in protein degradation at different levels of cellular life is discussed in relation with ageing. Though the exact underlying mechanism is unclear, an age-related decrease in proteasome activity weakens cellular capacity to remove oxidatively modified proteins and favours the development of diseases. Up-regulation of proteasome activity is characteristic of muscle wasting conditions, but may not be rate limiting. Meanwhile, enhanced presence of immunoproteasomes in ageing brain and muscle tissue could reflect a persistent inflammatory defence and anti-stress mechanism. Insulin/IGF-1 signalling regulates ageing in worms, flies and mammals. The insulin/IGF-1 receptor inhibits the forkhead transcription factor, FoxO through activating a cascade of conserved kinases. Longevity increases when FoxO becomes activated in response to reduced insulin/IGF-1 signalling. The ubiquitin-proteasome system plays a major role in signal transduction associated with stress and ageing. The understanding of specific proteolytic targeting paves the way for a new generation of active molecules that may control particular steps of normal and pathological ageing. © 2011 Elsevier Inc.
Szamado S.,Eotvos Lorand University
Animal Behaviour | Year: 2011
Honest signalling assumes a correlation between an observable signal and a nonobservable quality. There are many mutually nonexclusive mechanisms that can achieve such a correlation; however, for a long time the handicap principle has been identified as the main solution to this problem. In short, it claims that signals need to be costly to be honest and that honest signallers have to pay this extra cost at the equilibrium (i.e. signals have to be handicaps). Honesty, however, is not maintained by the realized cost paid by honest signallers at the equilibrium but by the potential cost of cheating. Whether this potential cost implies a realized cost for honest signallers depends on the biological details of the system and thus this cost cannot be predicted a priori without knowledge of these details. Accordingly, depending on these details, signals need not be costly to be honest, even under conflict of interest. In other words, handicapping equilibrium signals are not the only way to create a high potential cost of cheating. Here I first review the theoretical models supporting the above conclusion, and then I list mechanisms that can maintain a high potential cost of cheating without imposing extra realized cost (i.e. a handicap) on honest signallers at the equilibrium. Identifying and describing those constraints or the lack of them that might create a connection between these two types of cost should be a major research agenda. © 2010 The Association for the Study of Animal Behaviour.