Information Radiators (IRs) provide context-specific pieces of information in a semi-public place where a group of people can see it while working or passing-by. They can simplify information sharing “out-of-the-box”, foster awareness and socialization, create serendipity and enhance collaboration. Recent sociotechnical developments such as the establishment of permanent hybrid work settings as well as advances in the area of Human Computer Interaction (HCI) such as the emergence of Augmented Reality (AR) and Virtual Reality (VR) are likely to impact how IRs are being used – or even challenge their usefulness. In this article we discuss those developments and their possible implications for the design and use of IRs in the context of knowledge work in the next decades. We argue that IRs will probably remain an important part of future office environments providing awareness, supporting serendipity and building a situated social place for matchmaking as well as informal communication. Using new display and interaction technologies (such as AR) they might even grow in importance by enabling fluid work scenarios.

Colloidal semiconductor nanoplatelets are rectangular, quasi-two-dimensional crystallites that are only a few atomic layers thick. In the most heavily studied systems (such as CdE with E = S, Se, o...

We present a longitudinal case study of implementing interactive information radiators in a semi-public corporate context. Our insights include the importance of individually relevant and easily recognizable content with an aesthetic design suitable to be consumed peripherally and to entice multi-user interaction. Th e semi-public space poses special challenges for design and clearly shows the need for doing research through (longitudinal) deployment-based studies in the wild. On the other hand, the study outlines some challenges of doing longitudinal case studies of semi-public installations – particularly fi eld access and the availability of quantitative data.

In the synthesis of CdSe nanoplatelets, the selenium-to-selenide reduction pathway is unknown. We study solvent-free growth of CdSe nanoplatelets and identify bis(acyl) selenides as key reactive intermediates. Based on our findings, we prepare a series of bis(acyl) selenides that provide useful precursors with tailored reactivity for liquid-phase syntheses of nanoplatelets.

Ostwald ripening describes how the size distribution of colloidal particles evolves with time due to thermodynamic driving forces. Typically, small particles shrink and provide material to larger particles, which leads to size defocusing. Semiconductor nanoplatelets, thin quasi-two-dimensional (2D) particles with thicknesses of only a few atomic layers but larger lateral dimensions, offer a unique system to investigate this phenomenon. Experiments show that the distribution of nanoplatelet thicknesses does not defocus during ripening, but instead jumps sequentially from m to (m + 1) monolayers, allowing precise thickness control. We investigate how this counterintuitive process occurs in CdSe nanoplatelets. We develop a microscopic model that treats the kinetics and thermodynamics of attachment and detachment of monomers as a function of their concentration. We then simulate the growth process from nucleation through ripening. For a given thickness, we observe Ostwald ripening in the lateral direction, but none perpendicular. Thicker populations arise instead from nuclei that capture material from thinner nanoplatelets as they dissolve laterally. Optical experiments that attempt to track the thickness and lateral extent of nanoplatelets during ripening appear consistent with these conclusions. Understanding such effects can lead to better synthetic control, enabling further exploration of quasi-2D nanomaterials.

Colloidal nanoplatelets are atomically flat, quasi-two-dimensional sheets of semiconductor that can exhibit efficient, spectrally pure fluorescence. Despite intense interest in their properties, the mechanism behind their highly anisotropic shape and precise atomic-scale thickness remains unclear, and even counter-intuitive for commonly studied nanoplatelets that arise from isotropic crystal structures (such as zincblende CdSe and lead halide perovskites). Here we show that an intrinsic instability in growth kinetics can lead to such highly anisotropic shapes. By combining experimental results on the synthesis of CdSe nanoplatelets with theory predicting enhanced growth on narrow surface facets, we develop a model that explains nanoplatelet formation as well as observed dependencies on time and temperature. Based on standard concepts of volume, surface and edge energies, the resulting growth instability criterion can be directly applied to other crystalline materials. Thus, knowledge of this previously unknown mechanism for controlling shape at the nanoscale can lead to broader libraries of quasi-two-dimensional materials.

Colloidal nanoplatelets - quasi-two-dimensional sheets of semiconductor exhibiting efficient, spectrally pure fluorescence - form when liquid-phase syntheses of spherical quantum dots are modified. Despite intense interest in their properties, the mechanism behind their anisotropic shape and precise atomic-scale thickness remains unclear, and even counterintuitive when their crystal structure is isotropic. One commonly accepted explanation is that nanoclusters nucleate within molecular templates and then fuse. Here, we test this mechanism for zincblende nanoplatelets and show that they form instead due to an intrinsic instability in growth kinetics. We synthesize CdSe and CdS1-xSex nanoplatelets in template- and solvent-free isotropic melts containing only cadmium carboxylate and chalcogen, a finding incompatible with previous explanations. Our model, based on theoretical results showing enhanced growth on narrow surface facets, rationalizes nanoplatelet formation and experimental dependencies on temperature, time, and carboxylate length. Such understanding should lead to improved syntheses, controlled growth on surfaces, and broader libraries of nanoplatelet materials.

The structure of CdSe nanocrystals doped with 0.2%-2.5% Ag corresponding to 1.1-13.6 Ag atoms per nanocrystal is studied in detail by a combination of X-ray diffraction (XRD) and X-ray absorption spectroscopy at the Ag-K, Cd-K, and Se-K edges. X-ray absorption near-edge structure (XANES) data are compared with ab initio multiple scattering simulations. Extended X-ray absorption fine structure (EXAFS) spectra are analyzed by reverse Monte Carlo (RMC) simulations. The XANES data provide evidence that Ag is located inside the CdSe nanocrystals, and the EXAFS spectra show that the local structure of Ag can be described by tetrahedral interstitial sites in either wurtzite or zinc blende lattices similar to the coordination of Ag in Ag2Se.

Innerhalb der letzten Jahre haben verschiedene CSCW-Konzepte aufgrund der Verfugbarkeit ubiquitarer Benutzerschnittstellen Eingang in den Arbeitsalltag gefunden. Trotz der neuen Unterstutzungsformen erfordern bestimmte Szenarien – darunter kreative Gruppenprozesse, wie sie u.a. in Innovationsworkshops stattfinden – agilere Losungen, die verschiedenen Gruppenkonstellationen sowie Ubergange zwischen physischen und digitalen Artefakten unterstutzen. Der vorliegende Beitrag adressiert diese Herausforderungen mit einem Entwurf eines erweiterten Blended Interaction Konzepts.

Die Bereitstellung von Information fur die Teilnehmer einer (wissenschaftlichen) Tagung wird heute immer noch vorranging uber handisch gepflegte Webseiten und Printmedien abgewickelt. Der Einsatz neuer Benutzungsschnittstellen und Bedienkonzepte (z.B. mobile Konferenzanwendungen oder statio-nare Kiosksysteme mit interaktiven Vortragsdaten) fur diese Konferenzinformationssysteme ist dabei meist nur mit grosem Aufwand moglich. In vorliegenden Beitrag wird die fur die Tagung Mensch und Computer 2014 konzipierte personenzentrische Integrationsplattform vorgestellt und beispielhaft be-schrieben, wie damit innovative Dienste fur die Tagung realisiert werden konnen.

Although poorly understood, cation-exchange reactions are increasingly used to dope or transform colloidal semiconductor nanocrystals (quantum dots). We use density-functional theory and kinetic Monte Carlo simulations to develop a microscopic theory that explains structural, optical, and electronic changes observed experimentally in Ag-cation-exchanged CdSe nanocrystals. We find that Coulomb interactions, both between ionized impurities and with the polarized nanocrystal surface, play a key role in cation exchange. Our theory also resolves several experimental puzzles related to photoluminescence and electrical behavior in CdSe nanocrystals doped with Ag.

Community support is gaining more and more importance, especially in areas where peer-peer communication is a critical success factor. One important issue concerning community support is making the activities of the community visible to its members. Knowing better what other community members know and do can help to improve information supply by making information that is usually "hidden" inside of today's information systems available to the community and to outsiders. In this chapter, we present an approach that helps to make community awareness information visible in a sociotechnically integrated, interactive way. The concept is based on large touch screens or interactive projections in semipublic places such as lobbies or break rooms that help people to see, touch, and experience digital content, and to find contextual and timely information easily without having to look for it explicitly. Intuitive presentation and interaction possibilities on these sociotechnical systems, called CommunityMirrors, improve the visibility of information and awareness of what is happening in the underlying systems and corresponding communities, and they generate appreciation for information providers. In addition, through integration into the social context, CommunityMirrors support interpersonal communication between users standing in front of the screens and enhance the motivation of information providers to generate new content.

In diesem Beitrag stellen wir den MeetingMirror vor – ein auf grosen interaktiven Wandbildschirmen beruhende Losung zur Verbesserung der Informationsversorgung auf Tagungen. Basierend auf dem CommunityMirror-Prinzip halboffentlicher Informationsstrahler prasentieren wir kurz die Idee hinter dieser Losung sowie die fur die Tagung Mensch und Computer 2014 umgesetzte Funktionalitat. Der Schwerpunkt unseres Beitrags liegt dabei auf interessante Fragestellungen, die sich bei der Umsetzung ergeben haben und unsere zukunftige Entwicklungsagenda bestimmen werden.

Based on the success of social software, modern information and communication systems are continuously moving from an information-centric data perspective to a more person-centric view. Easy access to federated activity streams of colleagues and other awareness information that is aggregated from different distributed intra- and extra-organizational systems become more and more important for the daily knowledge work. The increasing number of platforms every person uses requires a flexible data integration solution that keeps track of the connections between the pieces of information and the persons involved in their creation in order to create a unified and aggregated view for work groups, teams and communities. This unified data collection is especially important for social network analysis and data mining as individual profiles and activities are meanwhile typically distributed over various source systems. In this paper we present the CommunityMashup, a person-centric multi-user data integration solution for social software and similar systems that facilitates data aggregation and filtering while retaining the link to the pieces of information in the source systems. To support continuous evolution and flexible integration of frequently changing heterogeneous APIs and interfaces, we apply a model-driven development approach based on a therefore created person-centric data model. In addition to the conceptual design of the CommunityMashup, we present a reference implementation based upon open source components. Our overall goal is to build a multi-user mashup middleware for social software that offers an universal entry point in combination with unified data access for different client devices and can be used in various application scenarios with regard to individually specified service levels, e.g. continuous availability.

Driven by the success of Social Software in private and enterprise settings (Web 2.0 / Enterprise 2.0) a lot of specialized services have moved mainstream over the last few years. Thus, the number of services one single person uses in cooperative settings for different dedicated purposes, e.g. joint document editing, group calendars, microblogs or Social Networking Services (SNS) has highly increased. One problem of that development is that the distribution of digital activities over different platforms and services makes it hard to stay informed about the activities of others because of their technical separation. As exactly this kind of awareness information is one of the key features of Social Software, because it allows implicit coordination for cooperative work settings this leads to the demand of a flexible data integration solution for social services. In this paper we describe our person-centric data integration approach that is aligned to the special characteristics of data from Social Software. It is inspired by the way humans are collaborating in the social web and therefore called “Wisdom of the Crowd Pattern”. This approach is technically implemented and integrated in the CommunityMashup.

Our daily work in the information society relies on creating, editing and collecting different information objects. Without additional presentation mechanisms these activities of particular knowledge workers remain hidden in the underlying IT systems. The resulting lack of awareness can lead to inefficient coordination as well as to the duplication of work in the worst case. Activity streams from Social Software offer new ways to increase the awareness, but the desktop-based user interfaces in typical organizational settings currently only utilize a small portion of their full sociotechnical potential. In this paper we present CommunityMirrors as one potential solution to this problem.