Gernot Bauer

Falling asleep with Angry Birds, Facebook and Kindle: a large scale study on mobile application usage

While applications for mobile devices have become extremely important in the last few years, little public information exists on mobile application usage behavior. We describe a large-scale deployment-based research study that logged detailed application usage information from over 4,100 users of Android-powered mobile devices. We present two types of results from analyzing this data: basic descriptive statistics and contextual descriptive statistics. In the case of the former, we find that the average session with an application lasts less than a minute, even though users spend almost an hour a day using their phones. Our contextual findings include those related to time of day and location. For instance, we show that news applications are most popular in the morning and games are at night, but communication applications dominate through most of the day. We also find that despite the variety of apps available, communication applications are almost always the first used upon a devices waking from sleep. In addition, we discuss the notion of a virtual application sensor, which we used to collect the data.

Exploiting the icon arrangement on mobile devices as information source for context-awareness

The contextual relevance of a service can only be determined by the human himself. However, a measure for relevance is required for context-aware service delivery. In this paper, we draw attention to icon arrangement on mobile devices as a new source of information for adaptive menus. We conducted contextual inquiries to investigate how people arrange icons on a grid-based menu. Our results show that context has an impact on how users arrange their menus: during different activities they prefer different icons to be placed at specific positions. We discuss layout options for icon menus and argue how the relevance can be approximated by observing the icon arrangement. Our results informed the design of a context-aware client for mobile services, which is presented as a prototype.

On Irreversibility and Radiation in Classical Electrodynamics of Point Particles

The direct interaction theory of electromagnetism, also known as Wheeler-Feynman electrodynamics, is often misinterpreted and found unappealing because of its reference to the absorber and, more importantly, to the so-called absorber condition.Here we remark that the absorber condition is indeed questionable and presumably not relevant for the explanation of irreversible radiation phenomena in our universe. What is relevant and deserves further scrutiny is the emergent effective description of a source particle in an environment. We therefore rephrase what we consider the relevant calculation by Wheeler and Feynman and comment on the status of the theory.

The mighty un-touchables: creating playful engagement on media façades

In this paper we investigate interaction with a media façade that is out of reach for touch-based interaction. We describe four different applications that utilize mobile devices to enable passers-by to interact with the façade. Each application has been designed constrained by limitations given by formal regulations of an editorial board (e.g. to prevent traffic distractions) and with the aim to catch the attention of passers-by to achieve interaction and keep the users engaged. Besides the description of the design and implementation of the different application, we report on initial feedback of users after a first preliminary user test that informs further development and design.

Maxwell-Lorentz Dynamics of Rigid Charges

We establish global existence and uniqueness of the dynamics of classical electromagnetism with extended, rigid charges and fields which need not to be square integrable. We also consider a modified theory of electromagnetism where no self-interaction occurs. That theory and our results are crucial for approaching the as yet unsolved problem of the general existence of dynamics of Wheeler-Feynman electromagnetism, which we shall address in the follow up paper. We conclude by discussing the energy conservation without self-interaction.

Visual highlighting on public displays

Public displays are often used to broadcast large amounts of information to people who pass by the displays. Flight departure boards, stock market displays and information systems at large conferences are examples for this kind of pervasive displays. While such displays serve a large number of users, one key disadvantage for individual users results from the difficulty to pinpoint which of the many items shown is relevant to them. This paper introduces a novel method to address this problem through visual highlighting and compares it to existing approaches. In doing so, we propose a set of criteria, that can also be used by designers of public display systems to select the most well suited approach for a given application scenario. In addition, these criteria can contribute towards ensuring the comparability of future studies in public display systems.

Hiding the complexity of LBS

While the demand for Location-based Services (LBS) is strongly increasing, technical laymen are not yet able to build and provide location-aware applications. This paper presents a radical simplification of the lifecycle of LBSs. An authoring toolkit enables non-technicians to easily develop context-aware mobile applications. In addition, an adaptive user interface makes the consumption of LBSs easier. The platform we present, in covering the whole LBS supply chain, is hiding the complexity of providing and consuming LBSs from the end-users.

Using mobile devices to enable visual multiplexing on public displays: three approaches compared

Public displays have become ubiquitous in many places regularly visited by large numbers of people (e.g., traffic hubs or malls). In addition to advertising they often provide information related to the location (e.g., time tables). However, individuals can have difficulties to find information relevant to them -- either due to information overload or lack of personalization. Multiplexing, as defined in information theory, can help to address this issue by increasing the number of available channels. We propose three methods for visual multiplexing, and report on a controlled lab-based comparison study. Our results indicate that visual multiplexing via mobile devices can be a feasible solution to provide personalized multimedia content on public displays, and that the three methods tested differ in terms of performance. We found that the content type shown has an impact on which method works best, and that self-reported workload differed according to content type and multiplexing method.

LBS 2.0 - Enabling User-Driven Provision and Context-Aware Utilisation of Location-Based Services

This poster presents a novel idea of how to provide users with location-based services. The key issues lie in radically simplifying the provision and the utilisation of services. Therefore we introduce Mobile Geo Widgets. Our objective is to make it possible for non-technicians to compose these via a Web toolkit without the need for specialized knowledge, and to enable people to use them on their mobile phones in a context-aware manner without any installation effort.

Running with Technology: Evaluating the Impact of Interacting with Wearable Devices on Running Movement

The use of wearable devices during running has become commonplace. Although there is ongoing research on interaction techniques for use while running, the effects of the resulting interactions on the natural movement patterns have received little attention so far. While previous studies on pedestrians reported increased task load and reduced walking speed while interacting, running movement further restricts interaction and requires minimizing interferences, e.g. to avoid injuries and maximize comfort. In this paper, we aim to shed light on how interacting with wearable devices affects running movement. We present results from a motion-tracking study (N=12) evaluating changes in movement and task load when users interact with a smartphone, a smartwatch, or a pair of smartglasses while running. In our study, smartwatches required less effort than smartglasses when using swipe input, resulted in less interference with the running movement and were preferred overall. From our results, we infer a number of guidelines regarding interaction design targeting runners.