73,211 research outputs found
Experiments in apply morphological analysis in speech recognition and their cognitive explanation
May 200
The role of nonthermal electrons in the optical continuum of stellar flares
We explore the possibility that the continuum emission in stellar flares is
powered by nonthermal electrons accelerated during the flares. We compute the
continuum spectra from an atmospheric model for a dMe star, AD Leo, at its
quiescent state, when considering the nonthermal excitation and ionisation
effects by precipitating electron beams. The results show that if the electron
beam has an energy flux large enough, the U band brightening and, in
particular, the U-B colour are roughly comparable with observed values for a
typical large flare. Moreover, for electron beams with a moderate energy flux,
a decrease of the emission at the Paschen continuum appears. This can explain
at least partly the continuum dimming observed in some stellar flares. Adopting
an atmospheric model for the flaring state can further raise the continuum flux
but it yields a spectral colour incomparable with observations. This implies
that the nonthermal effects may play the chief role in powering the continuum
emission in some stellar flares.Comment: 6 pages, 4 figures, LaTeX (psfigs.sty), to appear in MNRA
Is the Pedestrian going to Cross? Answering by 2D Pose Estimation
Our recent work suggests that, thanks to nowadays powerful CNNs, image-based
2D pose estimation is a promising cue for determining pedestrian intentions
such as crossing the road in the path of the ego-vehicle, stopping before
entering the road, and starting to walk or bending towards the road. This
statement is based on the results obtained on non-naturalistic sequences
(Daimler dataset), i.e. in sequences choreographed specifically for performing
the study. Fortunately, a new publicly available dataset (JAAD) has appeared
recently to allow developing methods for detecting pedestrian intentions in
naturalistic driving conditions; more specifically, for addressing the relevant
question is the pedestrian going to cross? Accordingly, in this paper we use
JAAD to assess the usefulness of 2D pose estimation for answering such a
question. We combine CNN-based pedestrian detection, tracking and pose
estimation to predict the crossing action from monocular images. Overall, the
proposed pipeline provides new state-of-the-art results.Comment: This is a paper presented in IEEE Intelligent Vehicles Symposium
(IEEE IV 2018
Dust Evolution and the Formation of Planetesimals
The solid content of circumstellar disks is inherited from the interstellar
medium: dust particles of at most a micrometer in size. Protoplanetary disks
are the environment where these dust grains need to grow at least 13 orders of
magnitude in size. Our understanding of this growth process is far from
complete, with different physics seemingly posing obstacles to this growth at
various stages. Yet, the ubiquity of planets in our galaxy suggests that planet
formation is a robust mechanism. This chapter focuses on the earliest stages of
planet formation, the growth of small dust grains towards the gravitationally
bound "planetesimals", the building blocks of planets. We will introduce some
of the key physics involved in the growth processes and discuss how they are
expected to shape the global behavior of the solid content of disks. We will
consider possible pathways towards the formation of larger bodies and conclude
by reviewing some of the recent observational advances in the field.Comment: 43 pages, 6 figures. Chapter in International Space Science Institute
(ISSI) Book on "The Disk in Relation to the Formation of Planets and their
Proto-atmospheres", published in Space Science Reviews by Springe
The Flatness of Mass-to-Light Ratio on Large Scales
It has been suggested that the mass-to-light () ratio of gravitationally
clustering objects is scale-independent on scales beyond galaxy clusters, and
may also be independent of the mass of the objects. In this paper, we show that
the scale behavior of ratio is closely related to the scaling of cosmic
structures larger than clusters. The scale dependence of the ratio can be
determined by comparing the observed scaling of richness function (RF) of
multi-scale identified objects with the model-predicted scaling of mass
function (MF) of large scale structures. Using the multi-scale identified
clusters from IRAS 1.2 Jy galaxy survey, we have made comparisons of the
observed RF scaling of IRAS -clusters with the MF scalings given by
simulations of three popular models SCDM, LCDM and OCDM. We find that, the M/L
ratio basically is scale-independent from the Abell radius up to about 24
Mpc, while it seems to show a slight, but systematical, increase over
this scale range. This result is weakly dependent on the cosmological
parameters.Comment: AAS Latex file, 8 pages+ 4 figures, accepted for publication in ApJ
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