Hydrogen sulphide regulates inward-rectifying K+ channels in conjunction with stomatal closure

Hydrogen sulphide (H2S) is the third biological gasotransmitter and, in animals, affects many physiological processes by modulating ion channels. H2S has been reported to protect plants from oxidative stress in diverse physiological responses. H2S closes stomata, but the underlying mechanism remains elusive. Here we report the selective inactivation of current carried by inward-rectifying K+ channels (IKIN) of tobacco guard cells and demonstrate its close parallel with stomatal closure evoked by submicromolar concentrations of H2S. Experiments to scavenge H2S suggested an effect that is separable from that of abscisic acid, which is associated with water stress. Thus, H2S appears to associate with a new and as yet unresolved signalling pathway that selectively targets IKIN

Multifractality of quantum wave functions in the presence of perturbations

We present a comprehensive study of the destruction of quantum multifractality in the presence of perturbations. We study diverse representative models displaying multifractality, including a pseudointegrable system, the Anderson model and a random matrix model. We apply several types of natural perturbations which can be relevant for experimental implementations. We construct an analytical theory for certain cases, and perform extensive large-scale numerical simulations in other cases. The data are analyzed through refined methods including double scaling analysis. Our results confirm the recent conjecture that multifractality breaks down following two scenarios. In the first one, multifractality is preserved unchanged below a certain characteristic length which decreases with perturbation strength. In the second one, multifractality is affected at all scales and disappears uniformly for a strong enough perturbation. Our refined analysis shows that subtle variants of these scenarios can be present in certain cases. This study could guide experimental implementations in order to observe quantum multifractality in real systems.Comment: 20 pages, 27 figure

Two scenarios for quantum multifractality breakdown

We expose two scenarios for the breakdown of quantum multifractality under the effect of perturbations. In the first scenario, multifractality survives below a certain scale of the quantum fluctuations. In the other one, the fluctuations of the wave functions are changed at every scale and each multifractal dimension smoothly goes to the ergodic value. We use as generic examples a one-dimensional dynamical system and the three-dimensional Anderson model at the metal-insulator transition. Based on our results, we conjecture that the sensitivity of quantum multifractality to perturbation is universal in the sense that it follows one of these two scenarios depending on the perturbation. We also discuss the experimental implications.Comment: 5 pages, 4 figures, minor modifications, published versio

On the semantic representation of risk

What are the defining features of lay people’s semantic representation of risk? We contribute to mapping the semantics of risk based on word associations to provide insight into both universal and individual differences in the representation of risk. Specifically, we introduce a mini-snowball word association paradigm and use the tools of network and sentiment analysis to characterize the semantics of risk. We find that association-based representations not only corroborate but also extend those extracted from past survey- and text-based approaches. Crucially, we find that the semantics of risk show universal properties and individual and group differences. Most notably, while semantic clusters generalize across languages, their frequency varies systematically across demographic groups, with older and female respondents showing more negative connotations and mentioning more often certain types of activities (e.g., recreational activities) relative to younger adults and males, respectively. Our work has general implications for the measurement of risk-related constructs by suggesting that “risk” can mean different things to different individuals

Semiclassical approach to fidelity amplitude

The fidelity amplitude is a quantity of paramount importance in echo type experiments. We use semiclassical theory to study the average fidelity amplitude for quantum chaotic systems under external perturbation. We explain analytically two extreme cases: the random dynamics limit --attained approximately by strongly chaotic systems-- and the random perturbation limit, which shows a Lyapunov decay. Numerical simulations help us bridge the gap between both extreme cases.Comment: 10 pages, 9 figures. Version closest to published versio

Soft Mobility Towards Ecological Sustainability in Lisbon Metropolitan Area – case study of Almada Municipality

Automobile traffic congestion and air pollution in the Lisbon Metropolitan Area (LMA), an area with close to 2.8 million people, has increased dramatically in the last 30 years as a result of suburban sprawl. The sheer size peri-urban areas have reached lends itself to urban politics and subsidized rents, an issue that has not yet been resolved due to lack of political will. This has driven down rental prices of old leases, accompanied by the degradation of buildings located in the city’s historic centre, and has also resulted in very high pricing of current leases inaccessible to most citizens. This is the way in which the peri-urban areas have grown, much like in many Western cities that have absorbed the rural exodus. Peri-urban areas also offer lower rents and housing prices than what historic centres offer. However, this growth has not been accompanied by a plan that accounts for the supply of transportation infrastructure and other public facilities or by relevant policies for the decentralization of employment. The relocation of various services, in addition to office locations, from the inner city to periurban areas increased inefficiency in regards to transportation and automobile use with serious consequences for public transportation. For example, in 1998 LMA residents completed 4.9 million daily commutes to or from Lisbon of which 24% were on foot and 76% by motorized transportation. Of the motorized commutes, 57% were Individual Transports (IT); 36% were Collective Transports (CT); while 7% were a combination of both (DGTT, 2000). Of the European Union-15 group members (the number of EU members prior to 2004), Portugal has the fastest-growing greenhouse emissions, with 40.5% in 2002 and 49% in 2010, rather than 27% mandated by the Kyoto Protocol. As a consequence, Portugal is facing a punitive fine in excess of 1.5 thousand million Euros for not complying with the emissions quota (REA, 2005). In October of 2012, the European Union Court of Justice declared that from 2005 to 2007, the Portuguese Republic did not meet the limit values established in Article 13 of Directive 2008/50/CE of the European Parliament and of the Council on the 21st of May, 2008 regarding the quality of ambient air and cleaner air in Europe. All these factors have resulted in suburbs where individuals are responsible for their own transportation, spending much of their time commuting to and from work and home, in addition to household budgets with a high incident of transportation costs. Europe has already proved that augmenting road and highway infrastructures only leads to more automobile traffic congestion, thereby demonstrating the need to find new models of mobility (Export Group on the Urban Environment, 1996) Containing clearly demarcated urban areas is one of the processes used to reduce traffic congestion and air pollution, among other benefits. Another process is the development of a multi-modal transportation system in which Soft Mobility plays an important role. It is implicit that transport actors include all means of transportation, not excluding the pedestrian and the bicyclist. Cycling is the fastest mode of transportation in short distances up to 3 kilometres (Dekoster and Schollaert, 2000), which means greater adjustability when connecting to public transportation interfaces. The current lack of accessibility to transportation interfaces is considered to be a factor in the decision individuals make to use automobiles (Lowe, 1990). Addressing this particular aspect calls for the creation of more cycling paths linked to public transportation systems, in addition to improving the security and comfort of bicycle parking facilities. As much as possible, cycling paths should be integrated with ecological structures, thereby raising the standard of environmental quality. This concept is true at local and municipal levels and on a regional scale. This article addresses this concept, showing the overall planning of projects with different types of Soft Mobility structures in various situations, from the restoration of old railroad lines to urban cycling networks with the underlying assumption of a mutually advantageous association between both mobility and ecological structures