95 research outputs found
A Deep Moving-camera Background Model
In video analysis, background models have many applications such as
background/foreground separation, change detection, anomaly detection,
tracking, and more. However, while learning such a model in a video captured by
a static camera is a fairly-solved task, in the case of a Moving-camera
Background Model (MCBM), the success has been far more modest due to
algorithmic and scalability challenges that arise due to the camera motion.
Thus, existing MCBMs are limited in their scope and their supported
camera-motion types. These hurdles also impeded the employment, in this
unsupervised task, of end-to-end solutions based on deep learning (DL).
Moreover, existing MCBMs usually model the background either on the domain of a
typically-large panoramic image or in an online fashion. Unfortunately, the
former creates several problems, including poor scalability, while the latter
prevents the recognition and leveraging of cases where the camera revisits
previously-seen parts of the scene. This paper proposes a new method, called
DeepMCBM, that eliminates all the aforementioned issues and achieves
state-of-the-art results. Concretely, first we identify the difficulties
associated with joint alignment of video frames in general and in a DL setting
in particular. Next, we propose a new strategy for joint alignment that lets us
use a spatial transformer net with neither a regularization nor any form of
specialized (and non-differentiable) initialization. Coupled with an
autoencoder conditioned on unwarped robust central moments (obtained from the
joint alignment), this yields an end-to-end regularization-free MCBM that
supports a broad range of camera motions and scales gracefully. We demonstrate
DeepMCBM's utility on a variety of videos, including ones beyond the scope of
other methods. Our code is available at https://github.com/BGU-CS-VIL/DeepMCBM .Comment: 26 paged, 5 figures. To be published in ECCV 202
Non-Markovian control of qubit thermodynamics by frequent quantum measurements
We explore the effects of frequent, impulsive quantum nondemolition
measurements of the energy of two-level systems (TLS), alias qubits, in contact
with a thermal bath. The resulting entropy and temperature of both the system
and the bath are found to be completely determined by the measurement rate, and
unrelated to what is expected by standard thermodynamical rules that hold for
Markovian baths. These anomalies allow for very fast control of heating,
cooling and state-purification (entropy reduction) of qubits, much sooner than
their thermal equilibration time.Comment: 8 pages, 9 figure
Formation of microtubule-based traps controls the sorting and concentration of vesicles to restricted sites of regenerating neurons after axotomy
Transformation of a transected axonal tip into a growth cone (GC) is a critical step in the cascade leading to neuronal regeneration. Critical to the regrowth is the supply and concentration of vesicles at restricted sites along the cut axon. The mechanisms underlying these processes are largely unknown. Using online confocal imaging of transected, cultured Aplysia californica neurons, we report that axotomy leads to reorientation of the microtubule (MT) polarities and formation of two distinct MT-based vesicle traps at the cut axonal end. Approximately 100 Ī¼m proximal to the cut end, a selective trap for anterogradely transported vesicles is formed, which is the plus end trap. Distally, a minus end trap is formed that exclusively captures retrogradely transported vesicles. The concentration of anterogradely transported vesicles in the former trap optimizes the formation of a GC after axotomy
The ConSurf-DB: pre-calculated evolutionary conservation profiles of protein structures
ConSurf-DB is a repository for evolutionary conservation analysis of the proteins of known structures in the Protein Data Bank (PDB). Sequence homologues of each of the PDB entries were collected and aligned using standard methods. The evolutionary conservation of each amino acid position in the alignment was calculated using the Rate4Site algorithm, implemented in the ConSurf web server. The algorithm takes into account the phylogenetic relations between the aligned proteins and the stochastic nature of the evolutionary process explicitly. Rate4Site assigns a conservation level for each position in the multiple sequence alignment using an empirical Bayesian inference. Visual inspection of the conservation patterns on the 3D structure often enables the identification of key residues that comprise the functionally important regions of the protein. The repository is updated with the latest PDB entries on a monthly basis and will be rebuilt annually. ConSurf-DB is available online at http://consurfdb.tau.ac.il
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