133,646 research outputs found
Atomic diffusion in the atmosphere of Feige 86
We have revisited the ultraviolet and optical spectra of the blue horizontal
branch star Feige 86. The new analysis finds the star cooler and more compact
than previously determined. The IUE spectrum of Feige 86 holds numerous
unidentified spectral lines of heavy metals, indicating efficient atomic
diffusion in the atmosphere. Because diffusion plays a key role in the
atmospheres of hot subdwarfs as well, it is indispensable to a better
understanding of subdwarf pulsations and evolution. Feige 86 looks like an
ideal target to confront diffusion theory with observations and test
spectroscopic techniques. Therefore, to advance our general understanding of
diffusion in stellar atmospheres we urge for new ultraviolet spectroscopy of
Feige 86 at the highest possible resolution with HST/STIS.Comment: 5 pages, 4 figures, accepted for publication in Open Astronomy as
part of the conference proceedings for the Eighth Meeting on Hot Subdwarf
Stars and Related Objects (sdOB8, Krakow
Achieving Secure and Efficient Cloud Search Services: Cross-Lingual Multi-Keyword Rank Search over Encrypted Cloud Data
Multi-user multi-keyword ranked search scheme in arbitrary language is a
novel multi-keyword rank searchable encryption (MRSE) framework based on
Paillier Cryptosystem with Threshold Decryption (PCTD). Compared to previous
MRSE schemes constructed based on the k-nearest neighbor searcha-ble encryption
(KNN-SE) algorithm, it can mitigate some draw-backs and achieve better
performance in terms of functionality and efficiency. Additionally, it does not
require a predefined keyword set and support keywords in arbitrary languages.
However, due to the pattern of exact matching of keywords in the new MRSE
scheme, multilingual search is limited to each language and cannot be searched
across languages. In this pa-per, we propose a cross-lingual multi-keyword rank
search (CLRSE) scheme which eliminates the barrier of languages and achieves
semantic extension with using the Open Multilingual Wordnet. Our CLRSE scheme
also realizes intelligent and per-sonalized search through flexible keyword and
language prefer-ence settings. We evaluate the performance of our scheme in
terms of security, functionality, precision and efficiency, via extensive
experiments
Movement in cluttered virtual environments
Imagine walking around a cluttered room but then having little idea of where you have traveled. This frequently happens when people move around small virtual environments (VEs), searching for targets. In three experiments, participants searched small-scale VEs using different movement interfaces, collision response algorithms, and fields of view. Participants' searches were most efficient in terms of distance traveled, time taken, and path followed when the simplest form of movement (view direction) was used in conjunction with a response algorithm that guided ("slipped") them around obstacles when collisions occurred. Unexpectedly, and in both immersive and desktop VEs, participants often had great difficulty finding the targets, despite the fact that participants could see the whole VE if they stood in one place and turned around. Thus, the trivial real-world task used in the present study highlights a basic problem with current VE systems
Visual object tracking performance measures revisited
The problem of visual tracking evaluation is sporting a large variety of
performance measures, and largely suffers from lack of consensus about which
measures should be used in experiments. This makes the cross-paper tracker
comparison difficult. Furthermore, as some measures may be less effective than
others, the tracking results may be skewed or biased towards particular
tracking aspects. In this paper we revisit the popular performance measures and
tracker performance visualizations and analyze them theoretically and
experimentally. We show that several measures are equivalent from the point of
information they provide for tracker comparison and, crucially, that some are
more brittle than the others. Based on our analysis we narrow down the set of
potential measures to only two complementary ones, describing accuracy and
robustness, thus pushing towards homogenization of the tracker evaluation
methodology. These two measures can be intuitively interpreted and visualized
and have been employed by the recent Visual Object Tracking (VOT) challenges as
the foundation for the evaluation methodology
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