Integration over the quantum diagonal subgroup and associated Fourier-like algebras

By analogy with the classical construction due to Forrest, Samei and Spronk we associate to every compact quantum group $\mathbb{G}$ a completely contractive Banach algebra $A_\Delta(\mathbb{G})$, which can be viewed as a deformed Fourier algebra of $\mathbb{G}$. To motivate the construction we first analyse in detail the quantum version of the integration over the diagonal subgroup, showing that although the quantum diagonal subgroups in fact never exist, as noted earlier by Kasprzak and So{\l}tan, the corresponding integration represented by a certain idempotent state on $C(\mathbb{G})$ makes sense as long as $\mathbb{G}$ is of Kac type. Finally we analyse as an explicit example the algebras $A_\Delta(O_N^+)$, $N\ge 2$, associated to Wang's free orthogonal groups, and show that they are not operator weakly amenable.Comment: Minor updates; Remark 5.7 has been added; 31 page

Novel types of anti-ecloud surfaces

In high power RF devices for space, secondary electron emission appears as the main parameter governing the multipactor effect and as well as the e-cloud in large accelerators. Critical experimental activities included development of coatings with low secondary electron emission yield (SEY) for steel (large accelerators) and aluminium (space applications). Coatings with surface roughness of high aspect ratio producing the so-call secondary emission suppression effect appear as the selected strategy. In this work a detailed study of the SEY of these technological coatings and also the experimental deposition methods (PVD and electrochemical) are presented. The coating-design approach selected for new low SEY coatings include rough metals (Ag, Au, Al), rough alloys (NEG), particulated and magnetized surfaces, and also graphene like coatings. It was found that surface roughness also mitigate the SEY deterioration due to aging processes.Comment: 4 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba, Italy; CERN Yellow Report CERN-2013-002, pp.153-15

Longitudinal coupled-bunch instability around 1 GHZ at the CERN PS booster

The fast-growing "Ring 4" instability occurring at intensities above 6.5 1012 protons in the top one of the four rings of the CERN PS Booster (PSB) is finally explained by an asymmetry in the 40 vacuum pump manifolds common to all rings. Impedance measurements (by wire method) and numerical calculations show a sharp resonant peak (Q~2000) at 1100 MHz and shunt impedances two times higher for the Ring 4 ports as compared to the other rings. This factor is sufficient to explain that the threshold of the instability falls below the maximum intensity only in Ring 4. A final, but labor-intensive and expensive, cure consists of inserting short-circuiting sleeves into all 160 beam ports. Results of beam and impedance measurements and the planned cure will be presented and discusse

“A right to ‘read’ for machines: Assessing a black-box analysis exception for data mining”

This panel looks into the impact of the current copyright framework in the European Union on text and data mining (TDM) and discusses the impact of introducing a TDM exception in EU copyright law. A design of this exception is proposed for the panel, and is partially based on findings in the Horizon 2020 FutureTDM project. This project aims to improve uptake of text and data mining (TDM) in the EU and, in that regard, has studied the legal barriers to TDM and will be developing and recommending a policy framework in the future. Part of this policy framework will consist of possible actions to be undertaken by the -European and national – legislators.A TDM exception is considered to include in the recommendations and we therefore broach the topic to discuss the possible legal, economic and practical impact of such an exception with experts from the field. The TDM exception, as proposed for this panel, is inspired by the “black-box analysis” exception from the Software Directive, which allows lawful users of a program to perform any of the acts of loading, displaying, running, transmitting or storing the program to “determine the ideas and principles” underlying it. The authors of the panel believe that this underlines the general principle of copyright law: namely, that ideas and facts are not protected. Therefore, proposition to be discussed is that a similar exception should be introduced for copyright law in general, that would allow reproductions to be made of works for the sole purpose of extracting facts and ideas underlying them. This would allow TDM activities, where machines ‘read’ lawfully accessed works just as the human reading of works does not require further authorization from the copyright holder

Raman spectroscopy of human teeth using integrated optical spectrometers

We have designed an arrayed-waveguide grating in silicon oxynitride technology for the detection of Raman signals from tooth enamel in the spectral region between 890 nm and 912 nm. The detected signals for both parallel and cross polarizations are used to distinguish between healthy and carious regions on the tooth surface of extracted human teeth. Our experimental results are in very good agreement with those achieved using conventional Raman spectrometers. Our results represent a step toward the realization of compact, hand-held, integrated spectrometers