5,214 research outputs found
Beef Cattle Instance Segmentation Using Fully Convolutional Neural Network
In this paper we present a novel instance segmentation algorithm that extends a fully convolutional network to learn to label objects separately without prediction of regions of interest. We trained the new algorithm on a challenging CCTV recording of beef cattle, as well as benchmark MS COCO and Pascal VOC datasets. Extensive experimentation showed that our approach outperforms the state-of-the-art solutions by up to 8% on our data
Circlator: automated circularization of genome assemblies using long sequencing reads
The assembly of DNA sequence data is undergoing a renaissance thanks to emerging technologies capable of producing reads tens of kilobases long. Assembling complete bacterial and small eukaryotic genomes is now possible, but the final step of circularizing sequences remains unsolved. Here we present Circlator, the first tool to automate assembly circularization and produce accurate linear representations of circular sequences. Using Pacific Biosciences and Oxford Nanopore data, Circlator correctly circularized 26 of 27 circularizable sequences, comprising 11 chromosomes and 12 plasmids from bacteria, the apicoplast and mitochondrion of Plasmodium falciparum and a human mitochondrion. Circlator is available at http://sanger-pathogens.github.io/circlator/
A geometric proof of the Kochen-Specker no-go theorem
We give a short geometric proof of the Kochen-Specker no-go theorem for
non-contextual hidden variables models. Note added to this version: I
understand from Jan-Aake Larsson that the construction we give here actually
contains the original Kochen-Specker construction as well as many others (Bell,
Conway and Kochen, Schuette, perhaps also Peres).Comment: This paper appeared some years ago, before the author was aware of
quant-ph. It is relevant to recent developments concerning Kochen-Specker
theorem
Designing zeolite catalysts for shape-selective reactions: Chemical modification of surfaces for improved selectivity to dimethylamine in synthesis from methanol and ammonia
The relative contributions of external and intracrystalline acidic sites of small pore H-RHO zeolite for the selective synthesis of methylamines from methanol and ammonia have been studied. Nonselective surface reactions which produce predominantly trimethylamine can be eliminated by “capping” the external acidic sites with trimethylphosphite (TMP) and other reagents, thus improving the selectivity toward the formation of dimethylamine. For small pore zeolites, neither the zeolite pore size nor the internal acidic sites is significantly affected by this treatment. In situ infrared and MAS-NMR studies show that TMP reacts irreversibly with the zeolite acidic sites via a modified Arbusov rearrangement to form surface-bound dimethylmethylphosphonate
Are the distributions of Fast Radio Burst properties consistent with a cosmological population?
High time resolution radio surveys over the last few years have discovered a
population of millisecond-duration transient bursts called Fast Radio Bursts
(FRBs), which remain of unknown origin. FRBs exhibit dispersion consistent with
propagation through a cold plasma and dispersion measures indicative of an
origin at cosmological distances. In this paper we perform Monte Carlo
simulations of a cosmological population of FRBs, based on assumptions
consistent with observations of their energy distribution, their spatial
density as a function of redshift and the properties of the interstellar and
intergalactic media. We examine whether the dispersion measures, fluences,
inferred redshifts, signal-to-noises and effective widths of known FRBs are
consistent with a cosmological population. Statistical analyses indicate that
at least 50 events at Parkes are required to distinguish between a constant
co-moving FRB density, and a FRB density that evolves with redshift like the
cosmological star formation rate density.Comment: 11 pages, 7 figures, 3 table
Relativistic spin precession in the binary PSR J11416545
PSR J11416545 is a precessing binary pulsar that has the rare potential to
reveal the two-dimensional structure of a non-recycled pulsar emission cone. It
has undergone of relativistic spin precession in the
years since its discovery. In this paper, we present a detailed Bayesian
analysis of the precessional evolution of the width of the total intensity
profile, to understand the changes to the line-of-sight impact angle ()
of the pulsar using four different physically motivated prior distribution
models. Although we cannot statistically differentiate between the models with
confidence, the temporal evolution of the linear and circular polarisations
strongly argue that our line-of-sight crossed the magnetic pole around MJD
54000 and that only two models remain viable. For both these models, it appears
likely that the pulsar will precess out of our line-of-sight in the next
years, assuming a simple beam geometry. Marginalising over suggests
that the pulsar is a near-orthogonal rotator and provides the first
polarization-independent estimate of the scale factor () that
relates the pulsar beam opening angle () to its rotational period ()
as : we find it to be at 1.4
GHz with 99\% confidence. If all pulsars emit from opposite poles of a dipolar
magnetic field with comparable brightness, we might expect to see evidence of
an interpulse arising in PSR J11416545, unless the emission is patchy.Comment: Accepted for publication in Astrophysical Journal Letter
Kondo resonances and anomalous gate dependence of electronic conduction in single-molecule transistors
We report Kondo resonances in the conduction of single-molecule transistors
based on transition metal coordination complexes. We find Kondo temperatures in
excess of 50 K, comparable to those in purely metallic systems. The observed
gate dependence of the Kondo temperature is inconsistent with observations in
semiconductor quantum dots and a simple single-dot-level model. We discuss
possible explanations of this effect, in light of electronic structure
calculations.Comment: 5 pages, four figures. Supplementary material at
http://www.ruf.rice.edu/~natelson/publications.htm
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