40,761 research outputs found
Ultrafast dynamics of finite Hubbard clusters - a stochastic mean-field approach
Finite lattice models are a prototype for strongly correlated quantum systems
and capture essential properties of condensed matter systems. With the dramatic
progress in ultracold atoms in optical lattices, finite fermionic Hubbard
systems have become directly accessible in experiments, including their
ultrafast dynamics far from equilibrium. Here, we present a theoretical
approach that is able to treat these dynamics in any dimension and fully
includes inhomogeneity effects. The method consists in stochastic sampling of
mean-field trajectories and is found to be more accurate and efficient than
current nonequilibrium Green functions approaches. This is demonstrated for
Hubbard clusters with up to 512 particles in one, two and three dimensions
Acquired Elliptocytosis as a Manifestation of Myelodysplastic Syndrome with Ring Sideroblasts and Multilineage Dysplasia.
Acquired elliptocytosis is a known but rarely described abnormality in the myelodysplastic syndromes (MDS). Here we report the case of an elderly male who was admitted to the hospital with chest pain, dyspnea, and fatigue and was found to be anemic with an elliptocytosis that had only recently been noted on peripheral smears of his blood. After bone marrow biopsy he was diagnosed with MDS with ring sideroblasts and multilineage dysplasia and acquired elliptocytosis. Here we report a rare case of acquired elliptocytosis cooccurring with MDS with ring sideroblasts and multilineage dysplasia
Insights into Analogy Completion from the Biomedical Domain
Analogy completion has been a popular task in recent years for evaluating the
semantic properties of word embeddings, but the standard methodology makes a
number of assumptions about analogies that do not always hold, either in recent
benchmark datasets or when expanding into other domains. Through an analysis of
analogies in the biomedical domain, we identify three assumptions: that of a
Single Answer for any given analogy, that the pairs involved describe the Same
Relationship, and that each pair is Informative with respect to the other. We
propose modifying the standard methodology to relax these assumptions by
allowing for multiple correct answers, reporting MAP and MRR in addition to
accuracy, and using multiple example pairs. We further present BMASS, a novel
dataset for evaluating linguistic regularities in biomedical embeddings, and
demonstrate that the relationships described in the dataset pose significant
semantic challenges to current word embedding methods.Comment: Accepted to BioNLP 2017. (10 pages
Mode engineering with a one-dimensional superconducting metamaterial
We propose a way to control the Josephson energy of a single Josephson
junction embedded in one- dimensional superconducting metamaterial: an
inhomogeneous superconducting loop, made out of a superconducting nanowire or a
chain of Josephson junctions. The Josephson energy is renormalized by the
electromagnetic modes propagating along the loop. We study the behaviour of the
modes as well as of their frequency spectrum when the capacitance and the
inductance along the loop are spatially modulated. We show that, depending on
the amplitude of the modulation, the renormalized Josephson energy is either
larger or smaller than the one found for a homogeneous loop. Using typical
experimental parameters for Josepshon junction chains and superconducting
nanowires, we conclude that this mode-engineering can be achieved with
currently available metamaterials
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