17 research outputs found
Mechanisms for leveraging models at runtime in self-adaptive software
Modern software systems are often required to adapt their behavior at runtime in order to maintain or enhance their utility in dynamic environments. Models at runtime research aims to provide suitable abstractions, techniques, and tools to manage the complexity of adapting software systems at runtime. In this chapter, we discuss challenges associated with developing mechanisms that leverage models at runtime to support runtime software adaptation. Specifically, we discuss challenges associated with developing effective mechanisms for supervising running systems, reasoning about and planning adaptations, maintaining consistency among multiple runtime models, and maintaining fidelity of runtime models with respect to the running system and its environment. We discuss related problems and state-of-the-art mechanisms, and identify open research challenges
Perfect quantum excitation energy transport via single edge perturbation in a complete network
The final publication is available at Springer via http://dx.doi.org/10.1140/epjb/e2017-80048-1We consider quantum excitation energy transport (EET) in a network of two-state nodes in the Markovian approximation by employing the Lindblad formulation. We find that EET from an initial site, where the excitation is inserted to the sink, is generally inefficient due to the inhibition of transport by localization of the excitation wave packet in a symmetric, fully-connected network. We demonstrate that the EET efficiency can be significantly increased up to ≈100% by perturbing hopping transport between the initial node and the one connected directly to the sink, while the rate of energy transport is highest at a finite value of the hopping parameter. We also show that prohibiting hopping between the other nodes which are not directly linked to the sink does not improve the efficiency. We show that external dephasing
noise in the network plays a constructive role for EET in the presence of localization in the network, while in the absence of localization it reduces the efficiency of EET. We also consider the influence of off-diagonal disorder in the hopping parameters of the network
Antarctic marine chemical ecology: what is next?
71 páginas, 1 tabla, 3 figuras.Antarctic ecosystems are exposed to unique environmental characteristics
resulting in communities structured both by biotic interactions such as
predation and competition, as well as abiotic factors such as seasonality and
ice-scouring. It is important to understand how ecological factors may trigger
chemical mechanisms in marine Antarctic organisms as a response for survival.
However, very little is known yet about the evolution of chemical compounds
in Antarctic organisms. Investigations in chemical ecology have demonstrated
over the last several years that defensive metabolites have evolved in numerous
representative Antarctic species. This contradicts earlier theories concerning
biogeographic variation in predation and chemical defenses. As reviewed here,
a number of interesting natural products have been isolated from Antarctic
organisms. However, we believe many more are still to be discovered. Currently, many groups such as microorganisms, planktonic organisms and deepsea fauna remain almost totally unknown regarding their natural products.
Furthermore, for many described compounds, ecological roles have yet to be
evaluated. In fact, much of the research carried out to date has been conducted
in the laboratory, and only in a few cases in an ecologically relevant context.
Therefore, there is a need to extend the experiments to the field, as done in
tropical and temperate marine ecosystems, or at least, to test the activity of the
chemicals in natural conditions and ecologically meaningful interactions.
Defense against predators is always one of the main topics when talking about
the roles of natural products in species interactions, but many other interesting
aspects, such as competition, chemoattraction, fouling avoidance and ultraviolet (UV) protection, also deserve further attention. In our opinion, challenging
future developments are to be expected for Antarctic marine chemical ecology
in the years to come.This work would not have been possible without the financial support of the Ministry of
Science and Education of Spain through different
grants along recent years in the general frame of
our ECOQUIM projects (ANT97-1590-E, ANT97-0273,
REN2002-12006-E ⁄ANT, REN2003-00545 and CGL2004-
03356 ⁄ANT).Peer reviewe