Population trapping in bound states during IR-assisted ultrafast photoionization of Ne+

We have investigated the photoionization of Ne+ in the combined field of a short infrared laser pulse and a delayed ultrashort pulse of the infrared laser's 23rd harmonic. We observe an ionization yield compatible with a picture in which one electron gets excited into Rydberg states by the harmonic laser field and is subsequently removed by the infrared laser field. Modulations are seen in the ionization yield as a function of time delay. These modulations originate from the trapping of population in low members of the Rydberg series with different states being populated at different ranges of delay times. The calculations further demonstrate that single-threshold calculations cannot reproduce the Ne+ photoionization yields obtained in multithreshold calculations.

Limitations of a measurement-assisted optomechanical route to quantum macroscopicity of superposition states

Optomechanics is currently believed to provide a promising route towards the achievement of genuine quantum effects at the large, massive-system scale. By using a recently proposed figure of merit that is well suited to address continuous-variable systems, in this paper we analyze the requirements needed for the state of a mechanical mode (embodied by an end-cavity cantilever or a membrane placed within an optical cavity) to be qualified as macroscopic. We show that, according to the phase space-based criterion that we have chosen for our quantitative analysis, the state achieved through strong single-photon radiation-pressure coupling to a quantized field of light and conditioned by measurements operated on the latter might be interpreted as macroscopically quantum. In general, though, genuine macroscopic quantum superpositions appear to be possible only under quite demanding experimental conditions

A box in the field: modernity and the barn in twentieth-century Ireland

This paper argues that the modern barn in Ireland is a complex social and architectural phenomena that is without, or has yet to find, a satisfactory discourse. Emerging in the middle third of the twentieth century, the modern barn – replete with corrugated iron and I-sections – continues to represent a presence in the Irish landscape whose ubiquity is as emphatic as its flexibility. It is, however, its universal properties that begin to suggest connections with wider narratives. The modernising aspects of the barn that appear in the 1920s and 30s begin to conflate with a rhetoric of architectural modernism which was simultaneously appearing across Europe. But while the relationship between high modernism’s critique of what it divined as the inspirational qualities of utilitarian buildings – Walter Gropius on grain silos, Le Corbusier on aircraft hangers etc. – has been well-documented, in Ireland this relationship perhaps contains another layer of complexity.
The barn’s consolidation as a modern type coincided with the search for a nation’s cultural identity after centuries of colonial rule. This tended to be an introspective vision that prioritised rural space over urban space, agriculture over industry, and imagined the small farm as a central tenet in the construction of a new State. This paper suggests that the twentieth-century barn – as a product of the mechanisation of agriculture promoted by the new administrations – is an iconic structure, emblematic of attempts to reconcile the contradictory forces and imagery of modernity with the mores of a traditional society. Moreover, given a cultural purview that was often ambivalent or even hostile to the ideologies and forms of modernity, the barn in Ireland is, perhaps, not so much the inspiration but the realisation of an architectural modernism in that country at its most pervasive, enduring and unself-conscious.

Rydberg structure associated with core-excited autoionizing states of the LiH radical

We have investigated inner-shell excitation of the LiH + molecular ion by electron impact within several different collision models to delineate Rydberg autoionizing resonance structure associated with the LiH + (1σ2σ 2 2 Σ + ) core-excited threshold. The minimal representation requires only the retention of the 1σ and 2σ molecular orbitals, in which the core-excited state involves the promotion of a single electron into the 2σ orbital. This model is extended to include two further representations, in which both the 3σ and 4σ orbitals obtained from a self-consistent field calculation improve target representation, correlation and support additional autoionization channels. This affects the autoionization widths and to a lesser degree the positions of the LiH (1σ2σ 2 n s, n p 1,3 Σ + ) resonance series. Comparing our work with calculations on the counterpart atomic Be system assists in the assignment of the core-excited molecular resonance states. The results from our investigation provide helpful insights into the study of inner-shell transitions produced by electron or photon impact in more complex diatomic molecules.

Trends in Approval Times for Genetically Engineered Crops in the United States and the European Union

Genetically engineered (GE) crops are subject to regulatory oversight to ensure their safety for humans and the environment. Their approval in the European Union (EU) starts with an application in a given Member State followed by a scientific step (risk assessment), and ends with a political decision-making step (risk management); and in the United States (US) it starts with a scientific (field trial) step and ends with a ‘bureaucratic’ decision-making step. We investigated trends for the time taken for these steps and the overall time taken for approving GE crops in the US and the EU (traders in these commodities). Results show that from 1996-2015 the overall time trend for approval in the EU decreased and then flattened off, with an overall mean completion-time of 1,763 days. In the US in 1998 there was a break in the trend of the overall approval time: Initially, from 1988 until 1997 the trend decreased with a mean approval time of 1,321 days; from 1998-2015, the trend almost stagnated with a mean approval time of 2,467 days.