454 research outputs found
A good balance of costs and benefits: convincing a university administration to support the installation of an interactive multi-application display system on campus
Interactive digital signage systems allow passers-by to take (temporary) control of a public display in order to select content and applications of interest, or even upload content of their own. Not surprisingly, display owners are hesitant to embrace such interactivity, given the uncertainty of what will be shown on their displays. In this paper we summarize our experience of deploying an interactive multi-application display system in the context of a university environment, and in particular our engagements with display owners (i.e., university administration) in order to convince them and get their support for the installation and deployment of such a system. We present the results of semi-structured interviews with display owners regarding their motivations, needs, and concerns with respect to the deployment of such a system at our university. While one cannot generalize from our results, we nevertheless believe that our experiences offer helpful advice to developers of such systems (and/or researchers interested in designing and studying them) in order to aid them in successfully gathering the support of these important stakeholders
Longitude : a privacy-preserving location sharing protocol for mobile applications
Location sharing services are becoming increasingly popular. Although many location sharing services allow users to set up privacy policies to control who can access their location, the use made by service providers remains a source of concern. Ideally, location sharing providers and middleware should not be able to access usersâ location data without their consent. In this paper, we propose a new location sharing protocol called Longitude that eases privacy concerns by making it possible to share a userâs location data blindly and allowing the user to control who can access her location, when and to what degree of precision. The underlying cryptographic algorithms are designed for GPS-enabled mobile phones. We describe and evaluate our implementation for the Nexus One Android mobile phone
Visual contrast response functions in Parkinson's disease: evidence from electroretinograms, visually evoked potentials and psychophysics
Objectives: Visual contrast detection thresholds and suprathreshold contrast discrimination thresholds were compared to luminance and flash/pattern electroretinograms (ERG) and visually evoked potentials (VEP) in patients with Parkinson's disease (n=31), patients with multiple system atrophy (n=6), patients with progressive supranuclear palsy (n=6) and control patients without central nervous disease (n=33).
Methods: The stimuli were luminance modulated full-field (flash) or horizontally oriented sinewave gratings (pattern), the latter having either a low (0.5 cycles/deg) or medium (4.0 cycles/deg) spatial frequency. Stimulus contrast ranged from 10 to 80% so that contrast response functions could be derived.
Results: Contrast thresholds were higher in the patients with Parkinson's disease than in the control patients. Contrast discrimination thresholds were also somewhat elevated in patients with Parkinson's disease. Pattern ERG amplitudes were significantly reduced in patients with Parkinson's disease for the medium spatial frequency stimulus, but less for the low spatial frequency and flash stimuli.
Conclusions: Our results suggest that Parkinsonâs disease impairs contrast processing in the retina. VEP amplitudes did not significantly differ between the groups for the conditions tested. Patients with progressive supranuclear palsy also showed impaired contrast perception and reduced ERG amplitudes, whereas patients with multiple system atrophy were less impaired
AN ENHANCED ALGORITHM FOR AUTOMATIC RADIOMETRIC HARMONIZATION OF HIGH-RESOLUTION OPTICAL SATELLITE IMAGERY USING PSEUDOINVARIANT FEATURES AND LINEAR REGRESSION
The growing number of available optical remote sensing data providing large spatial and temporal coverage enables the coherent and
gapless observation of the earthâs surface on the scale of whole countries or continents. To produce datasets of that size, individual
satellite scenes have to be stitched together forming so-called mosaics. Here the problem arises that the different images feature
varying radiometric properties depending on the momentary acquisition conditions. The interpretation of optical remote sensing data
is to a great extent based on the analysis of the spectral composition of an observed surface reflection. Therefore the normalization
of all images included in a large image mosaic is necessary to ensure consistent results concerning the application of procedures to
the whole dataset. In this work an algorithm is described which enables the automated spectral harmonization of satellite images to a
reference scene. As the stable and satisfying functionality of the proposed algorithm was already put to operational use to process a
high number of SPOT-4/-5, IRS LISS-III and Landsat-5 scenes in the frame of the European Environment Agency's
Copernicus/GMES Initial Operations (GIO) High-Resolution Layer (HRL) mapping of the HRL Forest for 20 Western, Central and
(South)Eastern European countries, it is further evaluated on its reliability concerning the application to newer Sentinel-2
multispectral imaging products. The results show that the algorithm is comparably efficient for the processing of satellite image data
from sources other than the sensor configurations it was originally designed for
SMILE CORRECTION IN THE ENMAP GROUND SEGMENT PROCESSOR: A QUALITATIVE ANALYSIS
The Environmental Mapping and Analysis Program (EnMAP) is an upcoming German hyperspectral satellite mission aiming to observe and characterize the Earthâs environment on a global scale. In course of a the development of the EnMAP ground segment processing chain, measures were taken to deal with probable spectral and spatial distortion effects of the sensor, that can only be addressed by post-processing once the satellite platform is launched into orbit. One of these effects is a pixel- and band-wise spectral distortion, the so called sensor smile effect. This paper describes the methods and performance of the smile correction process as implemented for the EnMAP ground segment processing chain, explaining design choices and difficulties currently encountered with the proposed approach and evaluating the results of the smile correction on basis of simulated EnMAP hyperspectral data
In-medium mass from the reaction
Data on the photoproduction of mesons on nuclei have been
re-analyzed in a search for in-medium modifications. The data were taken with
the Crystal Barrel(CB)/TAPS detector system at the ELSA accelerator facility in
Bonn. First results from the analysis of the data set were published by D.
Trnka et al. in Phys. Rev. Lett 94 (2005) 192303 \cite{david}, claiming a
lowering of the mass in the nuclear medium by 14 at normal nuclear
matter density. The extracted line shape was found to be sensitive to
the background subtraction. For this reason a re-analysis of the same data set
has been initiated and a new method has been developed to reduce the background
and to determine the shape and absolute magnitude of the background directly
from the data. Details of the re-analysis and of the background determination
are described. The signal on the target, extracted in the
re-analysis, does not show a deviation from the corresponding line shape on a
target, measured as reference. The earlier claim of an in-medium mass
shift is thus not confirmed. The sensitivity of the line shape to
different in-medium modification scenarios is discussed.Comment: 13 pages and 11 figures, submitted for publicatio
In Vivo Diagnostic Imaging Using Micro-CT: Sequential and Comparative Evaluation of Rodent Models for Hepatic/Brain Ischemia and Stroke
BACKGROUND: There is an increasing need for animal disease models for pathophysiological research and efficient drug screening. However, one of the technical barriers to the effective use of the models is the difficulty of non-invasive and sequential monitoring of the same animals. Micro-CT is a powerful tool for serial diagnostic imaging of animal models. However, soft tissue contrast resolution, particularly in the brain, is insufficient for detailed analysis, unlike the current applications of CT in the clinical arena. We address the soft tissue contrast resolution issue in this report. METHODOLOGY: We performed contrast-enhanced CT (CECT) on mouse models of experimental cerebral infarction and hepatic ischemia. Pathological changes in each lesion were quantified for two weeks by measuring the lesion volume or the ratio of high attenuation area (%HAA), indicative of increased vascular permeability. We also compared brain images of stroke rats and ischemic mice acquired with micro-CT to those acquired with 11.7-T micro-MRI. Histopathological analysis was performed to confirm the diagnosis by CECT. PRINCIPAL FINDINGS: In the models of cerebral infarction, vascular permeability was increased from three days through one week after surgical initiation, which was also confirmed by Evans blue dye leakage. Measurement of volume and %HAA of the liver lesions demonstrated differences in the recovery process between mice with distinct genetic backgrounds. Comparison of CT and MR images acquired from the same stroke rats or ischemic mice indicated that accuracy of volumetric measurement, as well as spatial and contrast resolutions of CT images, was comparable to that obtained with MRI. The imaging results were also consistent with the histological data. CONCLUSIONS: This study demonstrates that the CECT scanning method is useful in rodents for both quantitative and qualitative evaluations of pathologic lesions in tissues/organs including the brain, and is also suitable for longitudinal observation of the same animals
Modification of the -Meson Lifetime in Nuclear Matter
The photo production of mesons on the nuclei C, Ca, Nb and Pb has
been measured using the Crystal Barrel/TAPS detector at the ELSA tagged photon
facility in Bonn. The dependence of the meson cross section on the
nuclear mass number has been compared with three different types of models, a
Glauber analysis, a BUU analysis of the Giessen theory group and a calculation
by the Valencia theory group. In all three cases, the inelastic width
is found to be at normal nuclear matter density for an
average 3-momentum of 1.1 GeV/c. In the restframe of the meson, this
inelastic width corresponds to a reduction of the lifetime by
a factor . For the first time, the momentum dependent N
cross section has been extracted from the experiment and is in the range of 70
mb.Comment: 5 pages, 4 figure
Quasi-free photoproduction of eta-mesons of the neutron
Quasi-free photoproduction of eta-mesons off nucleons bound in the deuteron
has been measured with the CBELSA/TAPS detector for incident photon energies up
to 2.5 GeV at the Bonn ELSA accelerator. The eta-mesons have been detected in
coincidence with recoil protons and recoil neutrons, which allows a detailed
comparison of the quasi-free n(gamma,eta)n and p(gamma,eta)p reactions. The
excitation function for eta-production off the neutron shows a pronounced
bump-like structure at W=1.68 GeV (E_g ~ 1 GeV), which is absent for the
proton.Comment: accepted for publication in Phys. Rev. Let
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