204 research outputs found
Robust Outdoor Vehicle Visual Tracking Based on k-Sparse Stacked Denoising Auto-Encoder
Robust visual tracking for outdoor vehicle is still a challenging problem due to large object appearance variations caused by illumination variation, occlusion, and fast motion. In this chapter, k-sparse constraint is added to the encoder part of stacked auto-encoder network to learn more invariant feature of object appearance, and a stacked k-sparse-auto-encoder–based robust outdoor vehicle tracking method under particle filter inference is further proposed to solve the problem of appearance variance during the tracking. Firstly, a stacked denoising auto-encoder is pre-trained to learn the generic feature representation. Then, a k-sparse constraint is added to the stacked denoising auto-encoder, and the encoder of k-sparse stacked denoising auto-encoder is connected with a classification layer to construct a classification neural network. Finally, confidence of each particle is computed by the classification neural network and is used for online tracking under particle filter framework. Comprehensive tracking experiments are conducted on a challenging single-object tracking benchmark. Experimental results show that our tracker outperforms most state-of-the-art trackers
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The interplay between thermodynamics and kinetics in the solid-state synthesis of layered oxides.
In the synthesis of inorganic materials, reactions often yield non-equilibrium kinetic byproducts instead of the thermodynamic equilibrium phase. Understanding the competition between thermodynamics and kinetics is a fundamental step towards the rational synthesis of target materials. Here, we use in situ synchrotron X-ray diffraction to investigate the multistage crystallization pathways of the important two-layer (P2) sodium oxides Na0.67MO2 (M = Co, Mn). We observe a series of fast non-equilibrium phase transformations through metastable three-layer O3, O3' and P3 phases before formation of the equilibrium two-layer P2 polymorph. We present a theoretical framework to rationalize the observed phase progression, demonstrating that even though P2 is the equilibrium phase, compositionally unconstrained reactions between powder precursors favour the formation of non-equilibrium three-layered intermediates. These insights can guide the choice of precursors and parameters employed in the solid-state synthesis of ceramic materials, and constitutes a step forward in unravelling the complex interplay between thermodynamics and kinetics during materials synthesis
Nutrient co‐limitation in the subtropical Northwest Pacific
Nutrients limiting phytoplankton growth in the ocean are a critical control on ocean productivity and can underpin predicted responses to climate change. The extensive western subtropical North Pacific is assumed to be under strong nitrogen limitation, but this is not well supported by experimental evidence. Here, we report the results of 14 factorial nitrogen–phosphorus–iron addition experiments through the Philippine Sea, which demonstrate a gradient from nitrogen limitation in the north to nitrogen–iron co-limitation in the south. While nitrogen limited sites responded weakly to nutrient supply, co-limited sites bloomed with up to ~60-fold increases in chlorophyll a biomass that was dominated by initially undetectable diatoms. The transition in limiting nutrients and phytoplankton growth capacity was driven by a gradient in deep water nutrient supply, which was undetectable in surface concentration fields. We hypothesize that this large-scale phytoplankton response gradient is both climate sensitive and potentially important for regulating the distribution of predatory fish
Regulatory Feedback Loop of Two phz Gene Clusters through 5′-Untranslated Regions in Pseudomonas sp. M18
BACKGROUND: Phenazines are important compounds produced by pseudomonads and other bacteria. Two phz gene clusters called phzA1-G1 and phzA2-G2, respectively, were found in the genome of Pseudomonas sp. M18, an effective biocontrol agent, which is highly homologous to the opportunistic human pathogen P. aeruginosa PAO1, however little is known about the correlation between the expressions of two phz gene clusters. METHODOLOGY/PRINCIPAL FINDINGS: Two chromosomal insertion inactivated mutants for the two gene clusters were constructed respectively and the correlation between the expressions of two phz gene clusters was investigated in strain M18. Phenazine-1-carboxylic acid (PCA) molecules produced from phzA2-G2 gene cluster are able to auto-regulate expression itself and activate the expression of phzA1-G1 gene cluster in a circulated amplification pattern. However, the post-transcriptional expression of phzA1-G1 transcript was blocked principally through 5'-untranslated region (UTR). In contrast, the phzA2-G2 gene cluster was transcribed to a lesser extent and translated efficiently and was negatively regulated by the GacA signal transduction pathway, mainly at a post-transcriptional level. CONCLUSIONS/SIGNIFICANCE: A single molecule, PCA, produced in different quantities by the two phz gene clusters acted as the functional mediator and the two phz gene clusters developed a specific regulatory mechanism which acts through 5'-UTR to transfer a single, but complex bacterial signaling event in Pseudomonas sp. strain M18
Helicity amplitude analysis of
Using (447.9 2.3) million (3686) events collected with the BESIII
detector, the decays of (=0, 1, 2) have
been studied via the decay . The
branching fractions of the decays (=0, 1,
2) are determined to be ,
, and ,
respectively, which are the most precise measurements to date. From a helicity
amplitude analysis of the process , the polarization
parameters of the decays are determined for
the first time.Comment: 23 pages, 5 figure
Observation of the and evidence for a new vector charmonium-like state in
Cross sections for the process
at center-of-mass energies from to GeV are measured using data
samples with a total integrated luminosity of 21.2 fb collected by the
BESIII detector operating at the BEPCII storage ring. The state is
observed in the energy dependence of the cross section for the first time with a statistical significance of
26.0. In addition, an enhancement around GeV, called the
, is seen with a statistical significance of 4.2. There is no
clear structure around GeV. Using a fit with a coherent sum of three
Breit-Wigner functions, we determine the mass and width of the state
to be MeV/ and MeV,
respectively, and the mass and width of the state to be MeV/ and MeV, respectively,
where the first uncertainties are statistical and the second are systematic. In
addition, the average Born cross section ratio of to is measured to be
, or if
three-body phase space is considered.Comment: Update draft based the comments from PRD refere
Study of in decay
Using a sample of decays collected with
the BESIII detector, partial wave analyses of the decay are performed within the invariant mass region below 1.6 . The
covariant tensor amplitude method is used in both mass independent and mass
dependent approaches. Both analysis approaches exhibit dominant pseudoscalar
and axial vector components, and show good consistency for the other individual
components. Furthermore, the mass dependent analysis reveals that the
invariant mass spectrum for the pseudoscalar
component can be well described with two isoscalar resonant states, , the with a mass of
and a width of ,
and the with a mass of
and a width of .
The first and second uncertainties are statistical and systematic,
respectively. Alternate models for the pseudoscalar component are also tested,
but the description of the invariant mass spectrum
deteriorates significantly.Comment: 20 pages, 6 figures, 6 table
Precise Measurements of Decay Parameters and Asymmetry with Entangled Pairs
Based on 10 billion events collected at the BESIII experiment, a
search for violation in decay is performed in the difference
between -odd decay parameters for
and for by using the
process . With a
five-dimensional fit to the full angular distributions of the daughter baryon,
the most precise values for the decay parameters are determined to be
and , respectively. The and averaged
value of the decay parameter is extracted to be with unprecedented accuracy. The asymmetry
is determined to be
, which is one of the most precise measurements
in the baryon sector. The reported results for the decay parameter will play an
important role in the studies of the polarizations and violations for the
strange, charmed and beauty baryons
Observation of
By analyzing events collected with the
BESIII detector operating at the BEPCII collider, the decays of (, 1 and 2) are observed for the first time with
statistical significances of , , and ,
respectively. The product branching fractions of
and are measured. Dividing by the world
averages of the branching fractions of , the
branching fractions of decays are
determined to be ,
, and
for , 1 and 2, respectively, where the first uncertainties are statistical
and the second systematic.Comment: 9 pages, 4 figure
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