110 research outputs found
Registration Loss Learning for Deep Probabilistic Point Set Registration
Probabilistic methods for point set registration have interesting theoretical
properties, such as linear complexity in the number of used points, and they
easily generalize to joint registration of multiple point sets. In this work,
we improve their recognition performance to match state of the art. This is
done by incorporating learned features, by adding a von Mises-Fisher feature
model in each mixture component, and by using learned attention weights. We
learn these jointly using a registration loss learning strategy (RLL) that
directly uses the registration error as a loss, by back-propagating through the
registration iterations. This is possible as the probabilistic registration is
fully differentiable, and the result is a learning framework that is truly
end-to-end. We perform extensive experiments on the 3DMatch and Kitti datasets.
The experiments demonstrate that our approach benefits significantly from the
integration of the learned features and our learning strategy, outperforming
the state-of-the-art on Kitti. Code is available at
https://github.com/felja633/RLLReg.Comment: 3DV 202
Learning Fast and Robust Target Models for Video Object Segmentation
Video object segmentation (VOS) is a highly challenging problem since the
initial mask, defining the target object, is only given at test-time. The main
difficulty is to effectively handle appearance changes and similar background
objects, while maintaining accurate segmentation. Most previous approaches
fine-tune segmentation networks on the first frame, resulting in impractical
frame-rates and risk of overfitting. More recent methods integrate generative
target appearance models, but either achieve limited robustness or require
large amounts of training data.
We propose a novel VOS architecture consisting of two network components. The
target appearance model consists of a light-weight module, which is learned
during the inference stage using fast optimization techniques to predict a
coarse but robust target segmentation. The segmentation model is exclusively
trained offline, designed to process the coarse scores into high quality
segmentation masks. Our method is fast, easily trainable and remains highly
effective in cases of limited training data. We perform extensive experiments
on the challenging YouTube-VOS and DAVIS datasets. Our network achieves
favorable performance, while operating at higher frame-rates compared to
state-of-the-art. Code and trained models are available at
https://github.com/andr345/frtm-vos.Comment: CVPR 2020. arXiv admin note: substantial text overlap with
arXiv:1904.0863
Learning What to Learn for Video Object Segmentation
Video object segmentation (VOS) is a highly challenging problem, since the
target object is only defined during inference with a given first-frame
reference mask. The problem of how to capture and utilize this limited target
information remains a fundamental research question. We address this by
introducing an end-to-end trainable VOS architecture that integrates a
differentiable few-shot learning module. This internal learner is designed to
predict a powerful parametric model of the target by minimizing a segmentation
error in the first frame. We further go beyond standard few-shot learning
techniques by learning what the few-shot learner should learn. This allows us
to achieve a rich internal representation of the target in the current frame,
significantly increasing the segmentation accuracy of our approach. We perform
extensive experiments on multiple benchmarks. Our approach sets a new
state-of-the-art on the large-scale YouTube-VOS 2018 dataset by achieving an
overall score of 81.5, corresponding to a 2.6% relative improvement over the
previous best result.Comment: First two authors contributed equall
Cytochrome P450 2C19 Polymorphism is Associated with Reduced Clopidogrel Response in Cerebrovascular Disease
Swan foraging shapes spatial distribution of two submerged plants, favouring the preferred prey species
Compared to terrestrial environments, grazing intensity on belowground plant parts may be particularly strong in aquatic environments, which may have great effects on plant-community structure. We observed that the submerged macrophyte, Potamogeton pectinatus, which mainly reproduces with tubers, often grows at intermediate water depth and that P. perfoliatus, which mainly reproduces with rhizomes and turions, grows in either shallow or deep water. One mechanism behind this distributional pattern may be that swans prefer to feed on P. pectinatus tubers at intermediate water depths. We hypothesised that when swans feed on tubers in the sediment, P. perfoliatus rhizomes and turions may be damaged by the uprooting, whereas the small round tubers of P. pectinatus that escaped herbivory may be more tolerant to this bioturbation. In spring 2000, we transplanted P. perfoliatus rhizomes into a P. pectinatus stand and followed growth in plots protected and unprotected, respectively, from bird foraging. Although swan foraging reduced tuber biomass in unprotected plots, leading to lower P. pectinatus density in spring 2001, this species grew well both in protected and unprotected plots later that summer. In contrast, swan grazing had a dramatic negative effect on P. perfoliatus that persisted throughout the summer of 2001, with close to no plants in the unprotected plots and high densities in the protected plots. Our results demonstrate that herbivorous waterbirds may play a crucial role in the distribution and prevalence of specific plant species. Furthermore, since their grazing benefitted their preferred food source, the interaction between swans and P. pectinatus may be classified as ecologically mutualistic
Revealing the Appetite of the Marine Aquarium Fish Trade: The Volume and Biodiversity of Fish Imported into the United States
The aquarium trade and other wildlife consumers are at a crossroads forced by threats from global climate change and other anthropogenic stressors that have weakened coastal ecosystems. While the wildlife trade may put additional stress on coral reefs, it brings income into impoverished parts of the world and may stimulate interest in marine conservation. To better understand the influence of the trade, we must first be able to quantify coral reef fauna moving through it. Herein, we discuss the lack of a data system for monitoring the wildlife aquarium trade and analyze problems that arise when trying to monitor the trade using a system not specifically designed for this purpose. To do this, we examined an entire year of import records of marine tropical fish entering the United States in detail, and discuss the relationship between trade volume, biodiversity and introduction of non-native marine fishes. Our analyses showed that biodiversity levels are higher than previous estimates. Additionally, more than half of government importation forms have numerical or other reporting discrepancies resulting in the overestimation of trade volumes by 27%. While some commonly imported species have been introduced into the coastal waters of the USA (as expected), we also found that some uncommon species in the trade have also been introduced. This is the first study of aquarium trade imports to compare commercial invoices to government forms and provides a means to, routinely and in real time, examine the biodiversity of the trade in coral reef wildlife species
NETosis in Alzheimer's Disease
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the progressive deterioration of cognitive functions. Its neuropathological features include amyloid-\u3b2 (A\u3b2) accumulation, the formation of neurofibrillary tangles, and the loss of neurons and synapses. Neuroinflammation is a well-established feature of AD pathogenesis, and a better understanding of its mechanisms could facilitate the development of new therapeutic approaches. Recent studies in transgenic mouse models of AD have shown that neutrophils adhere to blood vessels and migrate inside the parenchyma. Moreover, studies in human AD subjects have also shown that neutrophils adhere and spread inside brain vessels and invade the parenchyma, suggesting these cells play a role in AD pathogenesis. Indeed, neutrophil depletion and the therapeutic inhibition of neutrophil trafficking, achieved by blocking LFA-1 integrin in AD mouse models, significantly reduced memory loss and the neuropathological features of AD. We observed that neutrophils release neutrophil extracellular traps (NETs) inside blood vessels and in the parenchyma of AD mice, potentially harming the blood-brain barrier and neural cells. Furthermore, confocal microscopy confirmed the presence of NETs inside the cortical vessels and parenchyma of subjects with AD, providing more evidence that neutrophils and NETs play a role in AD-related tissue destruction. The discovery of NETs inside the AD brain suggests that these formations may exacerbate neuro-inflammatory processes, promoting vascular and parenchymal damage during AD. The inhibition of NET formation has achieved therapeutic benefits in several models of chronic inflammatory diseases, including autoimmune diseases affecting the brain. Therefore, the targeting of NETs may delay AD pathogenesis and offer a novel approach for the treatment of this increasingly prevalent disease
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