6,017 research outputs found
Controlled Experimentation in Naturalistic Mobile Settings
Performing controlled user experiments on small devices in naturalistic
mobile settings has always proved to be a difficult undertaking for many Human
Factors researchers. Difficulties exist, not least, because mimicking natural
small device usage suffers from a lack of unobtrusive data to guide
experimental design, and then validate that the experiment is proceeding
naturally.Here we use observational data to derive a set of protocols and a
simple checklist of validations which can be built into the design of any
controlled experiment focused on the user interface of a small device. These,
have been used within a series of experimental designs to measure the utility
and application of experimental software. The key-point is the validation
checks -- based on the observed behaviour of 400 mobile users -- to ratify that
a controlled experiment is being perceived as natural by the user. While the
design of the experimental route which the user follows is a major factor in
the experimental setup, without check validations based on unobtrusive observed
data there can be no certainty that an experiment designed to be natural is
actually progressing as the design implies.Comment: 12 pages, 3 table
Fractional Chern Insulators in Bands with Zero Berry Curvature
Even if a noninteracting system has zero Berry curvature everywhere in the
Brillouin zone, it is possible to introduce interactions that stabilise a
fractional Chern insulator. These interactions necessarily break time-reversal
symmetry (either spontaneously or explicitly) and have the effect of altering
the underlying band structure. We outline a number of ways in which this may be
achieved, and show how similar interactions may also be used to create a
(time-reversal symmetric) fractional topological insulator. While our approach
is rigorous in the limit of long range interactions, we show numerically that
even for short range interactions a fractional Chern insulator can be
stabilised in a band with zero Berry curvature.Comment: 7 pages, 2 figures; Published versio
Perturbative Approach to Flat Chern Bands in the Hofstadter Model
We present a perturbative approach to the study of the Hofstadter model for
when the amount of flux per plaquette is close to a rational fraction. Within
this approximation certain eigenstates of the system are shown to be
multi-component wavefunctions that connect smoothly to the Landau levels of the
continuum. The perturbative corrections to these are higher Landau level
contributions that break rotational invariance and allow the perturbed states
to adopt the symmetry of the lattice. In the presence of interactions, this
approach allows for the calculation of generalised Haldane pseudopotentials,
and in turn, the many-body properties of the system. The method is sufficiently
general that it can apply to a wide variety of lattices, interactions and
magnetic field strengths.Comment: 40 pages, 15 figures; v2 includes minor changes, additional
references and an expanded background sectio
Modelling the spinning dust emission from LDN 1780
We study the anomalous microwave emission (AME) in the Lynds Dark Nebula
(LDN) 1780 on two angular scales. Using available ancillary data at an angular
resolution of 1 degree, we construct an SED between 0.408 GHz to 2997 GHz. We
show that there is a significant amount of AME at these angular scales and the
excess is compatible with a physical spinning dust model. We find that LDN 1780
is one of the clearest examples of AME on 1 degree scales. We detected AME with
a significance > 20. We also find at these angular scales that the
location of the peak of the emission at frequencies between 23-70 GHz differs
from the one on the 90-3000 GHz map. In order to investigate the origin of the
AME in this cloud, we use data obtained with the Combined Array for Research in
Millimeter-wave Astronomy (CARMA) that provides 2 arcmin resolution at 30 GHz.
We study the connection between the radio and IR emissions using morphological
correlations. The best correlation is found to be with MIPS 70m, which
traces warm dust (T50K). Finally, we study the difference in radio
emissivity between two locations within the cloud. We measured a factor
of difference in 30 GHz emissivity. We show that this variation can
be explained, using the spinning dust model, by a variation on the dust grain
size distribution across the cloud, particularly changing the carbon fraction
and hence the amount of PAHs.Comment: 14 pages, 11 figures, submitted to MNRA
Less users more confidence: How AOIs don’t affect scanpath trend analysis
User studies are typically difficult, recruiting enough users is often problematic and each experiment takes a considerable amount of time to be completed. In these studies, eye tracking is increasingly used which often increases time, therefore, the lower the number of users required for these studies the better for making these kinds of studies more practical in terms of economics and time expended. The possibility of achieving almost the same results with fewer users has already been raised. Specifically, the possibility of achieving 75% similarity to the results of 65 users with 27 users for searching tasks and 34 users for browsing tasks has been observed in scanpath trend analysis which discovers the most commonly followed path on a particular web page in terms of its visual elements or areas of interest (AOIs). Different approaches are available to segment or divide web pages into their visual elements or AOIs. In this paper, we investigate whether the possibility raised by the previous work is restricted to a particular page segmentation approach by replicating the experiments with two other segmentation approaches. The results are consistent with ~5% difference for the searching tasks and ~10% difference for the browsing tasks
Eye tracking scanpath analysis techniques on web pages: A survey, evaluation and comparison
Eye tracking has commonly been used to investigate how users interact with web pages, with the goal of improving their usability. This article comprehensively revisits the techniques that could be applicable to eye tracking data for analysing user scanpaths on web pages. It also uses a third-party eye tracking study to compare these techniques. This allows researchers to recognise existing techniques for their goals, understand how they work and know their strengths and limitations so that they can make an efficient choice for their studies. These techniques can mainly be used for calculating similarities/dissimilarities between scanpaths, computing transition probabilities between web page elements, detecting patterns in scanpaths and identifying common scanpaths. The scanpath analysis techniques are classified into four groups by their goals so that researchers can directly focus on the appropriate techniques for a sequential analysis of user scanpaths on web pages. This article also suggests dealing with the limitations of these techniques by pre-processing eye tracking data, considering cognitive processing and addressing their reductionist approach
Predicting whether users view dynamic content on the world wide web
Dynamic micro-content—interactive or updating widgets and features—is now widely used on the Web, but there is little understanding of how people allocate attention to it. In this paper we present the results of an eye tracking investigation examining how the nature of dynamic micro-content influences whether or not the user views it. We propose and validate the Dynamic Update Viewing-likelihood (DUV) model, a Chi-Squared Automatic Interaction Detector (CHAID) model that predicts with around 80 % accuracy whether users view dynamic updates as a function of how they are initiated, their size and their duration. The model is constructed with data from live websites and does not rely on knowledge of the user’s task to make its predictions, giving it a high-level of external validity. We discuss one example of its application: informing how dynamic content should be presented in audio via assistive technology for people with visual impairments
- …