1,940 research outputs found
Spectral Invariance of Non-Smooth Pseudodifferential Operators
In this paper we discuss some spectral invariance results for non-smooth
pseudodifferential operators with coefficients in H\"older spaces. In analogy
to the proof in the smooth case of Beals and Ueberberg, we use the
characterization of non-smooth pseudodifferential operators to get such a
result. The main new difficulties are the limited mapping properties of
pseudodifferential operators with non-smooth symbols and the fact, that in
general the composition of two non-smooth pseudodifferential operators is not a
pseudodifferential operator.
In order to improve these spectral invariance results for certain subsets of
non-smooth pseudodifferential operators with coefficients in H\"older spaces,
we improve the characterization of non-smooth pseudodifferential operators in a
previous work by the authors.Comment: 43 page
Stress Testing German Industry Sectors: Results from a Vine Copula Based Quantile Regression
Measuring interdependence between probabilities of default (PDs) in different
industry sectors of an economy plays a crucial role in financial stress
testing. Thereby, regression approaches may be employed to model the impact of
stressed industry sectors as covariates on other response sectors. We identify
vine copula based quantile regression as an eligible tool for conducting such
stress tests as this method has good robustness properties, takes into account
potential nonlinearities of conditional quantile functions and ensures that no
quantile crossing effects occur. We illustrate its performance by a data set of
sector specific PDs for the German economy. Empirical results are provided for
a rough and a fine-grained industry sector classification scheme. Amongst
others, we confirm that a stressed automobile industry has a severe impact on
the German economy as a whole at different quantile levels whereas e.g., for a
stressed financial sector the impact is rather moderate. Moreover, the vine
copula based quantile regression approach is benchmarked against both classical
linear quantile regression and expectile regression in order to illustrate its
methodological effectiveness in the scenarios evaluated.Comment: 12 page
High-field MRS
What is a high magnetic field? For in vivo MR systems using small animals like mice or rats, magnets of field-strengths as high as 11.7T/31cm (500 MHz) are available. For research in humans the highest field currently available is 9.4T/65cm (400 MHz), while in the clinic the highest field is 3-4T/95cm (130-170MHz). MR spectroscopy evolved rapidly over the last decades, and it is now an important tool in chemical and biological research focused on molecular composition, structure, and dynamics. Experiments initially conducted in cells and cell extracts, are now carried out in living animals and humans. Similarly, MRS applications in clinical diagnosis are growing steadily. The importance of field strength in such applications cannot be overemphasized. The several fold improved sensitivity at high fields enables the detailed quantitative study of both metabolic and neural signaling processes, as well as of their perturbations during disease
Soft-gluon Resummation for High-pT Inclusive-Hadron Production at COMPASS
We study the cross section for the photoproduction reaction gamma N -> h X in
fixed-target scattering at COMPASS, where the hadron h is produced at large
transverse momentum. We investigate the role played by higher-order QCD
corrections to the cross section. In particular we address large logarithmic
"threshold" corrections to the rapidity dependent partonic cross sections,
which we resum to all orders at next-to-leading accuracy. In our comparison to
the experimental data we find that the threshold contributions are large and
improve the agreement between data and theoretical predictions significantly.Comment: 13 pages, 7 figures, journal versio
Design Principles & Issues for Gaze and Pinch Interaction
With the imminent release of the Apple Vision Pro, a wave of innovative
technology will be going to get into people's hands. The "eyes and hands"
interface mixes up interaction design, indicating a need for principles,
frameworks, and standards. This article highlights 5 design principles and 5
issues for designing eyes & hands interfaces, drawing insights from both my
personal experience and scientific articles in the area of human-computer
interaction. Whether you're interested in design, tech, or research in this
evolving space, the article provides valuable perspectives to enhance your
understanding
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