Reflectance measurement of two-dimensional photonic crystal nanocavities with embedded quantum dots

The spectra of two-dimensional photonic crystal slab nanocavities with embedded InAs quantum dots are measured by photoluminescence and reflectance. In comparing the spectra taken by these two different methods, consistency with the nanocavities' resonant wavelengths is found. Furthermore, it is shown that the reflectance method can measure both active and passive cavities. Q-factors of nanocavities, whose resonant wavelengths range from 1280 to 1620 nm, are measured by the reflectance method in cross polarization. Experimentally, Q-factors decrease for longer wavelengths and the intensity, reflected by the nanocavities on resonance, becomes minimal around 1370 nm. The trend of the Q-factors is explained by the change of the slab thickness relative to the resonant wavelength, showing a good agreement between theory and experiment. The trend of reflected intensity by the nanocavities on resonance can be understood as effects that originate from the PC slab and the underlying air cladding thickness. In addition to three dimensional finite-difference time-domain calculations, an analytical model is introduced that is able to reproduce the wavelength dependence of the reflected intensity observed in the experiment.Comment: 24 pages, 7 figures, corrected+full versio

The use of provenance in information retrieval

The volume of electronic information that users accumulate is steadily rising. A recent study [2] found that there were on average 32,000 pieces of information (e-mails, web pages, documents, etc.) for each user. The problem of organizin

People-Powered Music: Using User-Generated Tags and Structure in Recommendations

Music recommenders often rely on experts to classify song facets like genre and mood, but user-generated folksonomies hold some advantages over expert classifications—folksonomies can reflect the same real-world vocabularies and categorizations that end users employ. We present an approach for using crowd-sourced common sense knowledge to structure user-generated music tags into a folksonomy, and describe how to use this approach to make music recommendations. We then empirically evaluate our “people-powered” structured content recommender against a more traditional recommender. Our results show that participants slightly preferred the unstructured recommender, rating more of its recommendations as “perfect” than they did for our approach. An exploration of the reasons behind participants’ ratings revealed that users behaved differently when tagging songs than when evaluating recommendations, and we discuss the implications of our results for future tagging and recommendation approaches

Annual Report 2010 - Institute for Nuclear Waste Disposal (KIT Scientific Reports ; 7600)

Contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2009. The structure of the report follows widely the organization of the institute according to research topics: Basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions

End-user experiences of visual and textual programming environments for Arduino

Arduino is an open source electronics platform aimed at hobbyists, artists, and other people who want to make things but do not necessarily have a background in electronics or programming. We report the results of an exploratory empirical study that investigated the potential for a visual programming environment to provide benefits with respect to efficacy and user experience to end-user programmers of Arduino as an alternative to traditional text-based coding. We also investigated learning barriers that participants encountered in order to inform future programming environment design. Our study provides a first step in exploring end-user programming environments for open source electronics platforms

Annual Report 2009 - Institute for Nuclear Waste Disposal (KIT Scientific Reports ; 7559)

Contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2009. The structure of the report follows widely the organization of the institute according to research topics: Basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions

Co-Created Personas: Engaging and Empowering Users with Diverse Needs Within the Design Process

Personas are powerful tools for designing technology and envisioning its usage. They are widely used to imagine archetypal users around whom to orient design work. We have been exploring co-created personas as a technique to use in co-design with users who have diverse needs. Our vision was that this would broaden the demographic and liberate co-designers of their personal relationship with a health condition. This paper reports three studies where we investigated using co-created personas with people who had Parkinson’s disease, dementia or aphasia. Observational data of co-design sessions were collected and analysed. Findings revealed that the co-created personas encouraged users with diverse needs to engage with co-designing. Importantly, they also aforded additional benefts including empowering users within a more accessible design process. Refecting on the outcomes from the diferent user groups, we conclude with a discussion of the potential for co-created personas to be applied more broadly

Finite-temperature hole dynamics in the t-J model: Exact results for high dimensions

We discuss the dynamics of a single hole in the t-J model at finite temperature, in the limit of large spatial dimensions. The problem is shown to yield a simple and physically transparent solution, that exemplifies the continuous thermal evolution of the underlying string picture from the T=0 string-pinned limit through to the paramagnetic phase.Comment: 6 pages, including 2 figure

Shielding effectiveness of original and modified building materials

This contribution deals with the determination of the shielding effectiveness of building materials used for office, factory and government buildings. Besides the examination of standard materials, measurements were also performed on modified materials, e.g. ferro concrete with enhanced shielding effectiveness due to a changed mixture or structure of the reinforcement. The measurements of original and modified materials were carried out in a fully anechoic room (FAR) according to IEEE 299-1997 from 80 MHz up to 10 GHz

Local bifurcations in differential equations with state-dependent delay

This is the author accepted manuscript. The final version is available from AIP Publishing via the DOI in this record.A common task when analysing dynamical systems is the determination of normal forms near local bifurcations of equilibria. As most of these normal forms have been classified and analysed, finding which particular class of normal form one encounters in a numerical bifurcation study guides follow-up computations. This paper builds on normal form algorithms for equilibria of delay differential equations with constant delay that were developed and implemented in DDE-Biftool recently. We show how one can extend these methods to delay-differential equations with state-dependent delay (sd-DDEs). Since higher degrees of regularity of local center manifolds are still open for sd-DDEs, we give an independent (still only partial) argument which phenomena from the truncated normal must persist in the full sd-DDE. In particular, we show that all invariant manifolds with a sufficient degree of normal hyperbolicity predicted by the normal form exist also in the full sd-DDEJ.S. gratefully acknowledges the financial support of the EPSRC via grants EP/N023544/1 and EP/N014391/1. J.S. has also received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement number 643073