Attosecond nanoplasmonic streaking of localized fields near metal nanospheres

Collective electron dynamics in plasmonic nanosystems can unfold on timescales in the attosec- ond regime and the direct measurements of plasmonic near-field oscillations is highly desirable. We report on numerical studies on the application of attosecond nanoplasmonic streaking spectroscopy to the measurement of collective electron dynamics in isolated Au nanospheres. The plasmonic field oscillations are induced by a few-cycle NIR driving field and are mapped by the energy of photoemitted electrons using a synchronized, time-delayed attosecond XUV pulse. By a detailed analysis of the amplitudes and phase shifts, we identify the different regimes of nanoplasmonic streaking and study the dependence on particle size, XUV photoelectron energy and emission position. The simulations indicate that the near-fields around the nanoparticles can be spatio-temporally reconstructed and may give detailed insight into the build-up and decay of collective electron motion.Comment: Revised versio

Superstring BRST Cohomology

We first derive all world-sheet action functionals for NSR superstring models with (1,1) supersymmetry and any number of abelian gauge fields, for gauge transformations of the standard form. Then we prove for these models that the BRST cohomology groups $H^g(s)$, $g<4$ (with the antifields taken into account) are isomorphic to those of the corresponding bosonic string models, whose cohomology is fully known. This implies that the nontrivial global symmetries, Noether currents, background charges, consistent deformations and candidate gauge anomalies of an NSR (1,1) superstring model are in one-to-one correspondence with their bosonic counterparts.Comment: LaTeX2e, 44 pages, minor correction

Combined grazing incidence RBS and TEM analysis of luminescent nano-SiGe/SiO2 multilayers.

Multilayer structures with five periods of amorphous SiGe nanoparticles/SiO2 layers with different thickness were deposited by Low Pressure Chemical Vapor Deposition and annealed to crystallize the SiGe nanoparticles. The use of grazing incidence RBS was necessary to obtain sufficient depth resolution to separate the signals arising from the individual layers only a few nm thick. The average size and areal density of the embedded SiGe nanoparticles as well as the oxide interlayer thickness were determined from the RBS spectra. Details of eventual composition changes and diffusion processes caused by the annealing processes were also studied. Transmission Electron Microscopy was used to obtain complementary information on the structural parameters of the samples in order to check the information yielded by RBS. The study revealed that annealing at 900 °C for 60 s, enough to crystallize the SiGe nanoparticles, leaves the structure unaltered if the interlayer thickness is around 15 nm or higher

Vol. 17, No. 2

Contents: Coming Together to Address Student Aggression and School Safety, by William C. Kling Recent Developments, by the Student Editorial Board Further References, compiled by Margaret A. Chaplanhttps://scholarship.kentlaw.iit.edu/iperr/1063/thumbnail.jp

Vol. 17, No. 2

Contents: Coming Together to Address Student Aggression and School Safety, by William C. Kling Recent Developments, by the Student Editorial Board Further References, compiled by Margaret A. Chaplanhttps://scholarship.kentlaw.iit.edu/iperr/1063/thumbnail.jp

“DALSTON! WHO ASKED U?”: A Knowledge-Centred Perspective on the Mapping of Socio-Spatial Relations in East London

Since the turn of the millennium, Dalston in the London Borough of Hackney has experienced fundamental change through public and private investment in new infrastructure and processes of urban restructuring. This was paralleled by the reform of the national planning system, which aimed to devolve decision-making to the local level and increase the possibilities for residents and stakeholders to participate in planning processes. However, the difficulty of translating local needs and aspirations into policy goals and broadly accepted area action plans resulted in a crisis, which, in 2018, led to the introduction of the Dalston Conversation and subsequently the revision of planning goals. It is in this context that the Relational States of Dalston mapping project generated and assembled local knowledge about the web of socio-spatial relations between different local actors and in this way highlighted the significance and fragility of the communities’ networks and their spatial dimensions. The collection, ordering, integration, and production of knowledge can be seen as part of the core work in urban planning processes and policymaking. Which forms of knowledge are routinely used in planning contexts and define the relationship between planning action and urban transformation? To what extent could the mapping of local community relations add to this knowledge and help to improve decision-making processes in contested spaces of knowledge? In what ways could a relational understanding of space and architectural modes of research and representation contribute to the analysis, conceptualisation, and communication of local community relations? This article engages with these questions, using the mapping project in Dalston as a case study

A high-gain Quantum free-electron laser: emergence & exponential gain

We derive an effective Dicke model in momentum space to describe collective effects in the quantum regime of a free-electron laser (FEL). The resulting exponential gain from a single passage of electrons allows the operation of a Quantum FEL in the high-gain mode and avoids the experimental challenges of an X-ray FEL oscillator. Moreover, we study the intensity fluctuations of the emitted radiation which turn out to be super-Poissonian

Schattentolerante Grasgemenge für Agroforstsysteme in der Legehennen-Haltung

This field-study focuses on provision of ground vegetation in a silvopoultry system.Silvopoultry is an agroforestry system in which trees are integrated in the chicken run in order to support natural behavior of laying hens. The trial was conducted on an organic farm in Southern England by the Organic Research Centre and aimed to assess the performance of different sward mixtures under trees. The sward mixtures tested included (1) a commercially available “standard” sward, (2) a sward with especially shade tolerant grasses and (3) a diverse sward including legumes and forage herbs. It was found that all mixtures established well under trees and didn’t show significant differences in productivity after six weeks. The “standard” sward mixture showed slightly higher biomass production. Sowing any of the sward mixtures appeared to reduce weed abundance compared to the control

Interferometric measurement of resonance transition wavelengths in C IV, Si IV, Al III, Al II, and Si II

We have made the first interferomeric measurements of the wavelengths of the important ultraviolet diagnostic lines in the spectra \ion{C}{4} near 155 nm and \ion{Si}{4} near 139 nm with a vacuum ultraviolet Fourier transform spectrometer and high-current discharge sources. The wavelength uncertainties were reduced by one order of magnitude for the \ion{C}{4} lines and by two orders of magnitude for the \ion{Si}{4} lines. Our measurements also provide accurate wavelengths for resonance transitions in \ion{Al}{3}, \ion{Al}{2}, and \ion{Si}{2}.Comment: 6 pages, 2 figures, 1 tabl