167,042 research outputs found
Aperture Supervision for Monocular Depth Estimation
We present a novel method to train machine learning algorithms to estimate
scene depths from a single image, by using the information provided by a
camera's aperture as supervision. Prior works use a depth sensor's outputs or
images of the same scene from alternate viewpoints as supervision, while our
method instead uses images from the same viewpoint taken with a varying camera
aperture. To enable learning algorithms to use aperture effects as supervision,
we introduce two differentiable aperture rendering functions that use the input
image and predicted depths to simulate the depth-of-field effects caused by
real camera apertures. We train a monocular depth estimation network end-to-end
to predict the scene depths that best explain these finite aperture images as
defocus-blurred renderings of the input all-in-focus image.Comment: To appear at CVPR 2018 (updated to camera ready version
Parallel algorithm with spectral convergence for nonlinear integro-differential equations
We discuss a numerical algorithm for solving nonlinear integro-differential
equations, and illustrate our findings for the particular case of Volterra type
equations. The algorithm combines a perturbation approach meant to render a
linearized version of the problem and a spectral method where unknown functions
are expanded in terms of Chebyshev polynomials (El-gendi's method). This
approach is shown to be suitable for the calculation of two-point Green
functions required in next to leading order studies of time-dependent quantum
field theory.Comment: 15 pages, 9 figure
Modulated Reheating and Large Non-Gaussianity in String Cosmology
A generic feature of the known string inflationary models is that the same
physics that makes the inflaton lighter than the Hubble scale during inflation
often also makes other scalars this light. These scalars can acquire
isocurvature fluctuations during inflation, and given that their VEVs determine
the mass spectrum and the coupling constants of the effective low-energy field
theory, these fluctuations give rise to couplings and masses that are modulated
from one Hubble patch to another. These seem just what is required to obtain
primordial adiabatic fluctuations through conversion into density perturbations
through the `modulation mechanism', wherein reheating takes place with
different efficiency in different regions of our Universe. Fluctuations
generated in this way can generically produce non-gaussianity larger than
obtained in single-field slow-roll inflation; potentially observable in the
near future. We provide here the first explicit example of the modulation
mechanism at work in string cosmology, within the framework of LARGE Volume
Type-IIB string flux compactifications. The inflationary dynamics involves two
light Kaehler moduli: a fibre divisor plays the role of the inflaton whose
decay rate to visible sector degrees of freedom is modulated by the primordial
fluctuations of a blow-up mode (which is made light by the use of
poly-instanton corrections). We find the challenges of embedding the mechanism
into a concrete UV completion constrains the properties of the non-gaussianity
that is found, since for generic values of the underlying parameters, the model
predicts a local bi-spectrum with fNL of order `a few'. However, a moderate
tuning of the parameters gives also rise to explicit examples with fNL O(20)
potentially observable by the Planck satellite.Comment: 42 pages, 2 figure
Volume visualization of time-varying data using parallel, multiresolution and adaptive-resolution techniques
This paper presents a parallel rendering approach that allows high-quality visualization of large time-varying volume datasets. Multiresolution and adaptive-resolution techniques are also incorporated to improve the efficiency of the rendering. Three basic steps are needed to implement this kind of an application. First we divide the task through decomposition of data. This decomposition can be either temporal or spatial or a mix of both. After data has been divided, each of the data portions is rendered by a separate processor to create sub-images or frames. Finally these sub-images or frames are assembled together into a final image or animation. After developing this application, several experiments were performed to show that this approach indeed saves time when a reasonable number of processors are used. Also, we conclude that the optimal number of processors is dependent on the size of the dataset used
Effective Lagrangians in Dimensions
The failure of the the loop expansion and effective lagrangians in two
dimensions, which traditionally hinges on a power counting argument is
considered. We establish that the book keeping device for the loop expansion, a
role played by (the reciprocal of) the pion-decay constant itself vanishes for
, thereby going beyond the power counting argument. We point the
connection of our results to the distinct phases of the candidate for the
effective lagrangians, the non-linear sigma model, in , and
eventually for . In light of our results, we recall some of the relavant
features of the multi-flavor Schwinger and large as candidates
for the underlying theory in .Comment: 13 pages plain LaTeX, to be run twice. Replaced with expanded and
corrected version. One footnote adde
Vzpostavitev socialnega svetovalnega dela v avstrijskih solah - od projekta do redne ponudbe
The contribution introduces the present situation and the basic challenges of school social work in Austria. Starting with the perception of a developing “knowledge society” (Höhne, 2004), school is seen as a life place at which social subjects and problems occur and are made manifest. The analyses are based in particular on empirical studies by the University of Klagenfurt (Sting & Leitner, 2011) and the University of Graz (Gspurning, Heimgartner, Pieber, & Sing, 2011), which were carried out in school social work facilities of Carinthia and Styria, but they also include Austrian-wide research projects. A methodical view is presented along the main target groups “pupils”, “teachers” and “parents”, and the basic orientations are discussed. The thematic analysis characterizes school social work as a multi-thematic service (e.g., conflicts, love, problems at school, problems of the family) that needs to oppose the reduction to single problem areas such as drug abuse or violence. The structural analyses render visible the meaning of spatial conditions, personnel competence and the social-spatial network. Finally, the possibilities of a lasting implementation of empirical research in school social work are discussed. (DIPF/Orig.
Effective Lagrangians in bound state calculations
In order to investigate specific aspects of bound state calculations in a
non-relativistic framework, we consider the energy-levels of a massive scalar
particle, which moves in an external field and interacts in addition with a
massless scalar particle. The discussion includes the following topics:
dimensionally regularized bound-state calculations, ultraviolet finiteness of
bound-state observables and their independence of the off-mass-shell behavior
of Green functions, non-renormalizable interactions, structure of the
non-relativistic two-point function, power counting and matching.Comment: 45 pages, 8 postscript figures, RevTeX styl
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