20 research outputs found
Learning Multi-Object Tracking and Segmentation from Automatic Annotations
In this work we contribute a novel pipeline to automatically generate
training data, and to improve over state-of-the-art multi-object tracking and
segmentation (MOTS) methods. Our proposed track mining algorithm turns raw
street-level videos into high-fidelity MOTS training data, is scalable and
overcomes the need of expensive and time-consuming manual annotation
approaches. We leverage state-of-the-art instance segmentation results in
combination with optical flow predictions, also trained on automatically
harvested training data. Our second major contribution is MOTSNet - a deep
learning, tracking-by-detection architecture for MOTS - deploying a novel
mask-pooling layer for improved object association over time. Training MOTSNet
with our automatically extracted data leads to significantly improved sMOTSA
scores on the novel KITTI MOTS dataset (+1.9%/+7.5% on cars/pedestrians), and
MOTSNet improves by +4.1% over previously best methods on the MOTSChallenge
dataset. Our most impressive finding is that we can improve over previous
best-performing works, even in complete absence of manually annotated MOTS
training data
2,4,5-Trihydroxy-3-methylacetophenone: A Cellulosic Chromophore as a Case Study of Aromaticity
The title compound
(2,4,5-trihydroxy-3-methylacetophenone, <b>1</b>) was isolated
as chromophore from aged cellulosic pulps.
The peculiar feature of the compound is its weak aromatic system that
can be converted into nonaromatic (quinoid or cyclic aliphatic) tautomers,
depending on the conditions and reaction partners. In alkaline media,
the participation of quinoid canonic forms weakens aromaticity, whereas
in neutral and acidic media, the strong hydrogen bond between the
2-hydroxyl group and the acetyl moiety plays an important role in
favoring quinoid tautomers. As a result, compound <b>1</b>,
with quinoid contributions being already âpresetâ, is
relatively stable toward oxidation and hardly undergoes alkylation
or nitration at CH-6, whereas the 2,4,5-trimethoxyderivative, being
âproperlyâ aromatic and even more sterically hindered,
is readily alkylated or nitrated. The lability of the aromatic system
is best demonstrated by the unusual reaction of <b>1</b> with
hydroxylamine, producing a tetroxime that is derived from its 2,4,5-triketo
tautomer. The high oxidative stability and low reactivity of the compound
hinder oxidative bleaching of this chromophore in cellulosic pulps
and detection reactions for analytical purposes
In Vitro Cytotoxicity of D18 and Y6 as Potential Organic Photovoltaic Materials for Retinal Prostheses
Millions of people worldwide are diagnosed with retinal dystrophies such as retinitis pigmentosa and age-related macular degeneration. A retinal prosthesis using organic photovoltaic (OPV) semiconductors is a promising therapeutic device to restore vision to patients at the late onset of the disease. However, an appropriate cytotoxicity approach has to be employed on the OPV materials before using them as retinal implants. In this study, we followed ISO standards to assess the cytotoxicity of D18, Y6, PFN-Br and PDIN individually, and as mixtures of D18/Y6, D18/Y6/PFN-Br and D18/Y6/PDIN. These materials were proven for their high performance as organic solar cells. Human RPE cells were put in direct and indirect contact with these materials to analyze their cytotoxicity by the MTT assay, apoptosis by flow cytometry, and measurements of cell morphology and proliferation by immunofluorescence. We also assessed electrophysiological recordings on mouse retinal explants via microelectrode arrays (MEAs) coated with D18/Y6. In contrast to PFN-Br and PDIN, all in vitro experiments show no cytotoxicity of D18 and Y6 alone or as a D18/Y6 mixture. We conclude that D18/Y6 is safe to be subsequently investigated as a retinal prosthesis
UDP-sulfoquinovose formation by Sulfolobus acidocaldarius
The UDP-sulfoquinovose synthase Agl3 from Sulfolobus acidocaldarius converts UDP-d-glucose and sulfite to UDP-sulfoquinovose, the activated form of sulfoquinovose required for its incorporation into glycoconjugates. Based on the amino acid sequence, Agl3 belongs to the short-chain dehydrogenase/reductase enzyme superfamily, together with SQD1 from Arabidopsis thaliana, the only UDP-sulfoquinovose synthase with known crystal structure. By comparison of sequence and structure of Agl3 and SQD1, putative catalytic amino acids of Agl3 were selected for mutational analysis. The obtained data suggest for Agl3 a modified dehydratase reaction mechanism. We propose that in vitro biosynthesis of UDP-sulfoquinovose occurs through an NAD+-dependent oxidation/dehydration/enolization/sulfite addition process. In the absence of a sulfur donor, UDP-d-glucose is converted via UDP-4-keto-d-glucose to UDP-d-glucose-5,6-ene, the structure of which was determined by 1H and 13C-NMR spectroscopy. During the redox reaction the cofactor remains tightly bound to Agl3 and participates in the reaction in a concentration-dependent manner. For the first time, the rapid initial electron transfer between UDP-d-glucose and NAD+ could be monitored in a UDP-sulfoquinovose synthase. Deuterium labeling confirmed that dehydration of UDP-d-glucose occurs only from the enol form of UDP-4-keto-glucose. The obtained functional data are compared with those from other UDP-sulfoquinovose synthases. A divergent evolution of Agl3 from S. acidocaldarius is suggested
Genome Analysis and Characterisation of the Exopolysaccharide Produced by Bifidobacterium longum subsp. longum 35624â˘.
The Bifibobacterium longum subsp. longum 35624⢠strain (formerly named Bifidobacterium longum subsp. infantis) is a well described probiotic with clinical efficacy in Irritable Bowel Syndrome clinical trials and induces immunoregulatory effects in mice and in humans. This paper presents (a) the genome sequence of the organism allowing the assignment to its correct subspeciation longum; (b) a comparative genome assessment with other B. longum strains and (c) the molecular structure of the 35624 exopolysaccharide (EPS624). Comparative genome analysis of the 35624 strain with other B. longum strains determined that the sub-speciation of the strain is longum and revealed the presence of a 35624-specific gene cluster, predicted to encode the biosynthetic machinery for EPS624. Following isolation and acid treatment of the EPS, its chemical structure was determined using gas and liquid chromatography for sugar constituent and linkage analysis, electrospray and matrix assisted laser desorption ionization mass spectrometry for sequencing and NMR. The EPS consists of a branched hexasaccharide repeating unit containing two galactose and two glucose moieties, galacturonic acid and the unusual sugar 6-deoxy-L-talose. These data demonstrate that the B. longum 35624 strain has specific genetic features, one of which leads to the generation of a characteristic exopolysaccharide
B. longum 35624 EPS characterization.
<p>(A) The 600 MHz <sup>1</sup>H NMR proton spectrum of the acid-treated <b>35624</b> EPS (D<sub>2</sub>O, 338 K) is illustrated. A part of the high-field region is displayed in the insert. <b>(B)</b> Expansion plot of the 150 MHz 13C NMR spectrum of the acid-treated <b>35624</b> exopolysaccharide. The anomeric signals on the left confirmed the presence of a hexasaccharide repeat unit.</p