4,773 research outputs found
Designing Usable and Secure Authentication Mechanisms for Public Spaces
Usable and secure authentication is a research field that approaches different challenges related to authentication, including security, from a human-computer interaction perspective. That is, work in this field tries to overcome security, memorability and performance problems that are related to the interaction with an authentication mechanism. More and more services that require authentication, like ticket vending machines or automated teller machines (ATMs), take place in a public setting, in which security threats are more inherent than in other settings. In this work, we approach the problem of usable and secure authentication for public spaces.
The key result of the work reported here is a set of well-founded criteria for the systematic evaluation of authentication mechanisms. These criteria are justified by two different types of investigation, which are on the one hand prototypical examples of authentication mechanisms with improved usability and security, and on the other hand empirical studies of security-related behavior in public spaces. So this work can be structured in three steps:
Firstly, we present five authentication mechanisms that were designed to overcome the main weaknesses of related work which we identified using a newly created categorization of authentication mechanisms for public spaces. The systems were evaluated in detail and showed encouraging results for future use. This and the negative sides and problems that we encountered with these systems helped us to gain diverse insights on the design and evaluation process of such systems in general. It showed that the development process of authentication mechanisms for public spaces needs to be improved to create better results. Along with this, it provided insights on why related work is difficult to compare to each other. Keeping this in mind, first criteria were identified that can fill these holes and improve design and evaluation of authentication mechanisms, with a focus on the public setting.
Furthermore, a series of work was performed to gain insights on factors influencing the quality of authentication mechanisms and to define a catalog of criteria that can be used to support creating such systems. It includes a long-term study of different PIN-entry systems as well as two field studies and field interviews on real world ATM-use. With this, we could refine the previous criteria and define additional criteria, many of them related to human factors. For instance, we showed that social issues, like trust, can highly affect the security of an authentication mechanism.
We used these results to define a catalog of seven criteria. Besides their definition, we provide information on how applying them influences the design, implementation and evaluation of a the development process, and more specifically, how adherence improves authentication in general. A comparison of two authentication mechanisms for public spaces shows that a system that fulfills the criteria outperforms a system with less compliance. We could also show that compliance not only improves the authentication mechanisms themselves, it also allows for detailed comparisons between different systems
GazeLockPatterns: Comparing Authentication Using Gaze and Touch for Entering Lock Patterns
In this work, we present a comparison between Android’s lock patterns for mobile devices (TouchLockPatterns) and an implementation of lock patterns that uses gaze input (GazeLockPatterns). We report on results of a between subjects study (N=40) to show that for the same layout of authentication interface, people employ comparable strategies for pattern composition. We discuss the pros and cons of adapting lock patterns to gaze-based user interfaces. We conclude by opportunities for future work, such as using data collected during authentication for calibrating eye trackers
Stabilization of the perovskite phase in the Y-Bi-O system by using a BaBiO buffer layer
A topological insulating phase has theoretically been predicted for the
thermodynamically unstable perovskite phase of YBiO. Here, it is shown
that the crystal structure of the Y-Bi-O system can be controlled by using a
BaBiO buffer layer. The BaBiO film overcomes the large lattice
mismatch of 12% with the SrTiO substrate by forming a rocksalt structure
in between the two perovskite structures. Depositing an YBiO film
directly on a SrTiO substrate gives a fluorite structure. However, when
the Y-Bi-O system is deposited on top of the buffer layer with the correct
crystal phase and comparable lattice constant, a single oriented perovskite
structure with the expected lattice constants is observed.Comment: 8 pages, 7 figures + 4 pages supporting informatio
The Three Hundred Project: Dynamical state of galaxy clusters and morphology from multi-wavelength synthetic maps
We study the connection between morphology and dynamical state of the
simulated galaxy clusters in from THE THREE HUNDRED Project. We
quantify cluster dynamical state using a combination of dynamical indicators
from theoretical measures and compare this combined parameter, , with the
results from morphological classifications. The dynamical state of the cluster
sample shows a continuous distribution from dynamically relaxed, more abundant
at lower redshift, to hybrid and disturbed. The dynamical state presents a
clear dependence on the radius, with internal regions more relaxed than
outskirts. The morphology from multi-wavelength mock observation of clusters in
X-ray, optical, and Sunyaev-Zel'dovich (SZ) effect images, is quantified by
-- a combination of six parameters for X-ray and SZ maps and the offsets
between the optical position of the Brightest Central Galaxy (BCG) and the
X-ray/SZ centroids. All the morphological parameters are highly correlated with
each other, while they show a moderately strong correlation with the dynamical
parameter. The X-ray or SZ peaks are less affected by the dynamical
state than centroids, which results in reliable tracers of the cluster density
peak. The principal source of contamination in the relaxed cluster fraction,
inferred from morphological parameters, is due to dynamically hybrid clusters.
Compared to individual parameters, which consider only one aspect of cluster
property (e.g. only clumping or asymmetry), the combined morphological and
dynamical parameters ( and ) collect more information and provide a
single and more accurate estimation of the cluster dynamical state.Comment: 18 pages, 12 figures. Accepted for publication in MNRA
Spectro-temporal shaping of seeded free-electron laser pulses
We demonstrate the ability to control and shape the spectro-temporal content
of extreme-ultraviolet (XUV) pulses produced by a seeded free-electron laser
(FEL). The control over the spectro-temporal properties of XUV light was
achieved by precisely manipulating the linear frequency chirp of the seed
laser. Our results agree with existing theory, which allows retrieving the
temporal properties (amplitude and phase) of the FEL pulse from measurements of
the spectra as a function of the FEL operating parameters. Furthermore, we show
the first direct evidence of the full temporal coherence of FEL light and
generate Fourier limited pulses by fine-tuning the FEL temporal phase. The
possibility to tailor the spectro-temporal content of intense short-wavelength
pulses represents the first step towards efficient nonlinear optics in the XUV
to X-ray spectral region and will enable precise manipulation of core-electron
excitations using the methods of coherent quantum control.Comment: 5 pages, 3 figure
On the sensitivity of the diffusion MRI signal to brain activity in response to a motor cortex paradigm
Diffusion functional MRI (dfMRI) is a promising technique to map functional
activations by acquiring diffusion-weighed spin-echo images. In previous
studies, dfMRI showed higher spatial accuracy at activation mapping compared to
classic functional MRI approaches. However, it remains unclear whether dfMRI
measures result from changes in the intra-/extracellular environment, perfusion
and/or T2 values. We designed an acquisition/quantification scheme to
disentangle such effects in the motor cortex during a finger tapping paradigm.
dfMRI was acquired at specific diffusion weightings to selectively suppress
perfusion and free-water diffusion, then times series of the apparent diffusion
coefficient (ADC-fMRI) and of the perfusion signal fraction (IVIM-fMRI) were
derived. ADC-fMRI provided ADC estimates sensitive to changes in perfusion and
free-water volume, but not to T2/T2* values. With IVIM-fMRI we isolated the
perfusion contribution to ADC, while suppressing T2 effects. Compared to
conventional gradient-echo BOLD fMRI, activation maps obtained with dfMRI and
ADC-fMRI had smaller clusters, and the spatial overlap between the three
techniques was below 50%. Increases of perfusion fractions were observed during
task in both dfMRI and ADC-fMRI activations. Perfusion effects were more
prominent with ADC-fMRI than with dfMRI but were significant in less than 25%
of activation ROIs. Taken together, our results suggest that the sensitivity to
task of dfMRI derives from a decrease of hindered diffusion and an increase of
the pseudo-diffusion signal fraction, leading to different, more confined
spatial activation patterns compared to classic functional MRI.Comment: Submitted to peer-reviewed journa
Cell Synchronization Enhances Nuclear Transformation and Genome Editing via Cas9 Enabling Homologous Recombination in Chlamydomonas reinhardtii
In Chlamydomonas reinhardtii, the model organism for eukaryotic green algae and plants, the processes of nuclear transformation and genome editing in particular are still marked by a low level of efficiency, and so intensive work is required in order to create and identify mutants for the investigation of basic physiological processes, as well as the implementation of biotechnological applications. In this work, we show that cell synchronization during the stages of the cell cycle, obtained from long-term cultivation under specific growth conditions, greatly enhances the efficiency of transformation and allows the identification of DNA repair mechanisms that occur preferentially at different stages of the cell cycle. We demonstrate that the transformation of synchronized cells at different times was differentially associated with nonhomologous end joining (NHEJ) and/or homologous recombination (FIR), and makes it possible to knock-in specific foreign DNA at the genomic nuclear location desired by exploiting HR This optimization greatly reduces the overall complexity of the genome editing procedure and creates new opportunities for altering genes and their products
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