1,180 research outputs found
Challenging Common Assumptions in the Unsupervised Learning of Disentangled Representations
The key idea behind the unsupervised learning of disentangled representations
is that real-world data is generated by a few explanatory factors of variation
which can be recovered by unsupervised learning algorithms. In this paper, we
provide a sober look at recent progress in the field and challenge some common
assumptions. We first theoretically show that the unsupervised learning of
disentangled representations is fundamentally impossible without inductive
biases on both the models and the data. Then, we train more than 12000 models
covering most prominent methods and evaluation metrics in a reproducible
large-scale experimental study on seven different data sets. We observe that
while the different methods successfully enforce properties ``encouraged'' by
the corresponding losses, well-disentangled models seemingly cannot be
identified without supervision. Furthermore, increased disentanglement does not
seem to lead to a decreased sample complexity of learning for downstream tasks.
Our results suggest that future work on disentanglement learning should be
explicit about the role of inductive biases and (implicit) supervision,
investigate concrete benefits of enforcing disentanglement of the learned
representations, and consider a reproducible experimental setup covering
several data sets
An evergreen mind and a heart for the colors of fall
With the finest biochemical and molecular approaches, convincing explorative strategies, and long-term vision, Stefan Hörtensteiner succeeded in elucidating the biochemical pathway responsible for chlorophyll degradation. After having contributed to the identification of key chlorophyll degradation products in the course of the past 25 years, he gradually identified and characterized most of the crucial players in the PAO/phyllobilin degradation pathway of chlorophyll. He was one of the brightest plant biochemists of his generation, and his work opened doors to a better understanding of plant senescence, tetrapyrrole homeostasis, and their complex regulation. He sadly passed away on 5 December 2020, aged 57
A Commentary on the Unsupervised Learning of Disentangled Representations
The goal of the unsupervised learning of disentangled representations is to
separate the independent explanatory factors of variation in the data without
access to supervision. In this paper, we summarize the results of Locatello et
al., 2019, and focus on their implications for practitioners. We discuss the
theoretical result showing that the unsupervised learning of disentangled
representations is fundamentally impossible without inductive biases and the
practical challenges it entails. Finally, we comment on our experimental
findings, highlighting the limitations of state-of-the-art approaches and
directions for future research
Integration Studies and Beam Physics for the Project of the NA60+ Heavy-Ion Experiment at CERN
NA60+ is a fixed target experiment proposed in the framework of the Physics Beyond Colliders programme at CERN. It aims to precisely measure the hard and electromagnetic probes in nuclear collisions. Initially proposed for the underground cavern ECN3 with very high beam intensities, the experiment now foresees a location in the EHN1 surface hall which was shown to have a limited impact on the physics performance in spite of a significant reduction of beam intensity and detector size. The potential installation and operation of the experiment with the ion beams from the Super Proton Synchrotron (SPS) has been examined regarding detector integration, beam physics, radiation protection and shielding requirements. The integration of the experiment is considered feasible and would require a significant reconfiguration of the zone in regard to shielding and layout. The first estimate for the integration cost is 1.4 MCHF
Extrusion-Based Ceramics Printing with Strictly-Continuous Deposition
International audienceWe propose a method for integrated tool path planning and support structuregeneration tailored to the specific constraints of extrusion-based ceramicsprinting. Existing path generation methods for thermoplastic materials relyon transfer moves to navigate between different print paths in a given layer.However, when printing with clay, these transfer moves can lead to severeartifacts and failure. Our method eliminates transfer moves altogether bygenerating deposition paths that are continuous within and across layers.Our algorithm is implemented as a sequential top-down pass through thelayer stack. In each layer, we detect points that require support, connectsupport points and model paths, and optimize the shape of the resultingcontinuous path with respect to length, smoothness, and distance to themodel. For each of these subproblems, we propose dedicated solutions thattake into account the fabrication constraints imposed by printable clay.We evaluate our method on a set of examples with multiple disconnectedcomponents and challenging support requirements. Comparisons to existingpath generation methods designed for thermoplastic materials show that ourmethod substantially improves print quality and often makes the differencebetween success and failure
Association of RANTES G-403A gene polymorphism with increased risk of coronary arteriosclerosis
Aims Polymorphisms in the RANTES (G-403A), monocyte chemoattractant protein-1 (MCP-1; A-2518G), stromal cell-derived factor-1ÎČ (SDF-1ÎČ; G801A), and C-C chemokine receptor-5 (CCR5; Î32) genes have been associated with functional effects. These chemokines have been implicated in leucocyte recruitment to arterial lesions. In a case-control study, we explored relations between these polymorphisms and coronary artery disease (CAD), with respect to angiographic abnormalities and acute coronary syndromes (ACS). Methods and Results The LUdwigshafen Risk and Cardiovascular health (LURIC) cohort was genotyped by RFLP-PCR. Based on coronary angiography, individuals were sub-divided into CAD cases \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \end{document} and controls \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \end{document}. RANTES-403 genotype frequencies were significantly different in cases and controls \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \end{document}, as were A allele carrier frequencies (36.01% vs. 30.19%, OR=1.30 [95%-CI=1.06-1.60], \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \end{document}). By multivariate analysis, RANTES A-403 retained significant association with CAD \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \end{document}. RANTES A-403 was associated with increased ACS prevalence (OR=1.36 [95%-CI=1.08-1.71], \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \end{document}). MCP-1 G-2518, SDF-1ÎČ A801, and CCR5 Î32 were not associated with CAD. Conclusions RANTES A-403 was associated with CAD independently from conventional risk factors and CRP or fibrinogen as inflammatory biomarkers. The association was enhanced in smokers and ACS, conditions where platelet activation and inflammation predominate. RANTES A-403 may increase genetic susceptibility to CA
Use of (Q)SAR genotoxicity predictions and fuzzy multicriteria decision-making for priority ranking of ethoxyquin transformation products
Ethoxyquin (EQ; 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline) has been used as an antioxidant in feed for pets and food-producing animals, including farmed fish such as Atlantic salmon. In Europe, the authorization for use of EQ as a feed additive was suspended, due to knowledge gaps concerning the presence and toxicity of EQ transformation products (TPs). Recent analytical studies focusing on the detection of EQ TPs in farmed Atlantic salmon feed and fillets reported the detection of a total of 27 EQ TPs, comprising both known and previously not described EQ TPs. We devised and applied an in silico workflow to rank these EQ TPs according to their genotoxic potential and their occurrence data in Atlantic salmon feed and fillet. Ames genotoxicity predictions were obtained applying a suite of five (quantitative) structureâactivity relationship ((Q)SAR) tools, namely VEGA, TEST, LAZAR, Derek Nexus and Sarah Nexus. (Q)SAR Ames genotoxicity predictions were aggregated using fuzzy analytic hierarchy process (fAHP) multicriteria decision-making (MCDM). A priority ranking of EQ TPs was performed based on combining both fAHP ranked (Q)SAR predictions and analytical occurrence data. The applied workflow prioritized four newly identified EQ TPs for further investigation of genotoxicity. The fAHP-based prioritization strategy described here, can easily be applied to other toxicity endpoints and groups of chemicals for priority ranking of compounds of most concern for subsequent experimental and mechanistic toxicology analyses.publishedVersio
Star-Shaped Metrics for Mechanical Metamaterial Design
Special issue, SIGGRAPH 2019International audienceWe present a method for designing mechanical metamaterials based on the novel concept of Voronoi diagrams induced by star-shaped metrics. As one of its central advantages, our approach supports interpolation between arbitrary metrics. This capability opens up a rich space of structures with interesting aesthetics and a wide range of mechanical properties, including isotropic, tetragonal, orthotropic, as well as smoothly graded materials. We evaluate our method by creating large sets of example structures, provided as accompanying material. We validate the mechanical properties predicted by simulation through tensile tests on a set of physical prototypes
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