61 research outputs found
Singlet Ground State of the Quantum Antiferromagnet Ba3CuSb2O9
We present local probe results on the honeycomb lattice antiferromagnet
Ba3CuSb2O9. Muon spin relaxation measurements in zero field down to 20 mK show
unequivocally that there is a total absence of spin freezing in the ground
state. Sb NMR measurements allow us to track the intrinsic susceptibility of
the lattice, which shows a maximum at around 55 K and drops to zero in the
low-temperature limit. The spin-lattice relaxation rate shows two
characteristic energy scales, including a field-dependent crossover to
exponential low-temperature behavior, implying gapped magnetic excitations.Comment: Accepted for publication in Physical Review Letter
Probabilistic Super-Resolution of Solar Magnetograms: Generating Many Explanations and Measuring Uncertainties
Machine learning techniques have been successfully applied to super-resolution tasks on natural images where visually pleasing results are sufficient. However in many scientific domains this is not adequate and estimations of errors and uncertainties are crucial. To address this issue we propose a Bayesian framework that decomposes uncertainties into epistemic and aleatoric uncertainties. We test the validity of our approach by super-resolving images of the Sun's magnetic field and by generating maps measuring the range of possible high resolution explanations compatible with a given low resolution magnetogram
Single-Frame Super-Resolution of Solar Magnetograms: Investigating Physics-Based Metrics \& Losses
Breakthroughs in our understanding of physical phenomena have traditionally followed improvements in instrumentation. Studies of the magnetic field of the Sun, and its influence on the solar dynamo and space weather events, have benefited from improvements in resolution and measurement frequency of new instruments. However, in order to fully understand the solar cycle, high-quality data across time-scales longer than the typical lifespan of a solar instrument are required. At the moment, discrepancies between measurement surveys prevent the combined use of all available data. In this work, we show that machine learning can help bridge the gap between measurement surveys by learning to \textbf{super-resolve} low-resolution magnetic field images and \textbf{translate} between characteristics of contemporary instruments in orbit. We also introduce the notion of physics-based metrics and losses for super-resolution to preserve underlying physics and constrain the solution space of possible super-resolution outputs
Deep Graph Matching via Blackbox Differentiation of Combinatorial Solvers
Building on recent progress at the intersection of combinatorial optimization
and deep learning, we propose an end-to-end trainable architecture for deep
graph matching that contains unmodified combinatorial solvers. Using the
presence of heavily optimized combinatorial solvers together with some
improvements in architecture design, we advance state-of-the-art on deep graph
matching benchmarks for keypoint correspondence. In addition, we highlight the
conceptual advantages of incorporating solvers into deep learning
architectures, such as the possibility of post-processing with a strong
multi-graph matching solver or the indifference to changes in the training
setting. Finally, we propose two new challenging experimental setups. The code
is available at https://github.com/martius-lab/blackbox-deep-graph-matchingComment: ECCV 2020 conference pape
Phase II, randomized, placebo-controlled study of dovitinib in combination with fulvestrant in postmenopausal patients with HR+, HER2â breast cancer that had progressed during or after prior endocrine therapy
Structural, morphological and electrical properties of Cu2ZnSn1-xSixS4 (x = 0.8, x = 1) for solar-cells applications
International audienc
Structure Flexibility of the Cu(2)ZnSnS(4) Absorber in Low-Cost Photovoltaic Cells: From the Stoichiometric to the Copper-Poor Compounds
International audienceHere we present for the very first time a single-crystal investigation of the Cu-poor Zn-rich derivative of Cu(2)ZnSnS(4). Nowadays, this composition is considered as the one that delivers the best photovoltaic performances in the specific domain of Cu(2)ZnSnS(4)-based thin-film solar cells. The existence of this nonstoichiometric phase is definitely demonstrated here in an explicit and unequivocal manner on the basis of powder and single-crystal X-ray diffraction analyses coupled with electron microprobe analyses. Crystals are tetragonal, space group I Ì
4, Z = 2, with a = 5.43440(15) Ă
and c = 10.8382(6) Ă
for Cu(2)ZnSnS(4) and a = 5.43006(5) Ă
and c = 10.8222(2) Ă
for Cu(1.71)Zn(1.18)Sn(0.99)S(4)
Bis(1-ethyl-3-methylimidazolium) 3,6-diselanylidene-1,2,4,5-tetraselena-3,6-diphosphacyclohexane-3,6-diselenolate
In the title compound, 2C6H11N2+·P2Se82− or [EMIM]2P2Se8 (EMIM = 1-ethyl-3-methylimidazolium), the anions, located about inversion centers between EMIM cations, exhibit a cyclohexane-like chair conformation. The cations are found in columns along the a axis, with centroid–centroid distances of 3.8399 (3) and 4.7530 (2) Å. The observed P—Se distances and Se—P—Se angles agree with other salts of this anion
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