8,662 research outputs found
Lie groupoids and algebroids applied to the study of uniformity and homogeneity of material bodies
A Lie groupoid, called \textit{material Lie groupoid}, is associated in a
natural way to any elastic material. The corresponding Lie algebroid, called
\textit{material algebroid}, is used to characterize the uniformity and the
homogeneity properties of the material. The relation to previous results in
terms of structures is discussed in detail. An illustrative example is
presented as an application of the theory
Nuclear effects in neutrino and antineutrino CCQE scattering at MINERvA kinematics
We compare the charged-current quasielastic neutrino and antineutrino
observables obtained in two different nuclear models, the phenomenological
SuperScaling Approximation and the Relativistic Mean Field approach, with the
recent data published by the MINERvA Collaboration. Both models provide a good
description of the data without the need of an ad hoc increase in the mass
parameter in the axial-vector dipole form factor. Comparisons are also made
with the MiniBooNE results where different conclusions are reached.Comment: 6 pages, 7 figures, Accepted for publication in Physical Review
Impact of low-energy nuclear excitations on neutrino-nucleus scattering at MiniBooNE and T2K kinematics
[Background] Meticulous modeling of neutrino-nucleus interactions is
essential to achieve the unprecedented precision goals of present and future
accelerator-based neutrino-oscillation experiments. [Purpose] Confront our
calculations of charged-current quasielastic cross section with the
measurements of MiniBooNE and T2K, and to quantitatively investigate the role
of nuclear-structure effects, in particular, low-energy nuclear excitations in
forward muon scattering. [Method] The model takes the mean-field (MF) approach
as the starting point, and solves Hartree-Fock (HF) equations using a Skyrme
(SkE2) nucleon-nucleon interaction. Long-range nuclear correlations are taken
into account by means of the continuum random-phase approximation (CRPA)
framework. [Results] We present our calculations on flux-folded double
differential, and flux-unfolded total cross sections off C and compare
them with MiniBooNE and (off-axis) T2K measurements. We discuss the importance
of low-energy nuclear excitations for the forward bins. [Conclusions] The CRPA
predictions describe the gross features of the measured cross sections. They
underpredict the data (more in the neutrino than in the antineutrino case)
because of the absence of processes beyond pure quasielastic scattering in our
model. At very forward muon scattering, low-energy nuclear excitations ( 50 MeV) account for nearly 50% of the flux-folded cross section.Comment: 8 pages, 9 figures. Version published in Physical Review
Membrane protein Oca3 is essential to keep structural integrity of mitochondria and endoplasmic reticulum
Mitochondrial function is tightly conserved through evolution since it becomes essential for the fitness of any eukaryotic cell. Defective function of this organelle represents the cellular basis of some severe diseases in humans. Thus, the characterization of genes involved in the correct mitochondrial structure and function is critical to understand and treating these diseases. In our laboratory, using the fission yeast as a model, we are characterising the function of oca3 gene, the ortholog of EMC2 gene in human. This gene is predicted to be a member of the ER membrane protein complex involved in the mitochondrion-endoplasmic reticulum membrane tethering1. We find the protein in the non-aqueous phase in cell extracts and Oca3-mCherry tagging actually decorates most cell membranes. Oca3 over-expression cause lethality2 and the gene deletion becomes cold-sensitive. In both situations aberrant mitochondria aggregations are observed and endoplasmic reticulum seems disorganised. Interestingly, addition of Tween20 restores the viability of oca3 deletion at low temperature. This result suggests that Oca3 may have a role in membrane fluidity homeostasis. In addition to this, we will analyse different gene interaction between some of the EMC complex members to clarify both, the importance of Oca3 for the complex and the importance of the complex itself for the cell
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Tough Tables: Carefully Evaluating Entity Linking for Tabular Data
Table annotation is a key task to improve querying the Web and support the Knowledge Graph population from legacy sources (tables). Last year, the SemTab challenge was introduced to unify different efforts to evaluate table annotation algorithms by providing a common interface and several general-purpose datasets as a ground truth. The SemTab dataset is useful to have a general understanding of how these algorithms work, and the organizers of the challenge included some artificial noise to the data to make the annotation trickier. However, it is hard to analyze specific aspects in an automatic way. For example, the ambiguity of names at the entity-level can largely affect the quality of the annotation. In this paper, we propose a novel dataset to complement the datasets proposed by SemTab. The dataset consists of a set of high-quality manually-curated tables with non-obviously linkable cells, i.e., where values are ambiguous names, typos, and misspelled entity names not appearing in the current version of the SemTab dataset. These challenges are particularly relevant for the ingestion of structured legacy sources into existing knowledge graphs. Evaluations run on this dataset show that ambiguity is a key problem for entity linking algorithms and encourage a promising direction for future work in the field
Abundant Z-cyanomethanimine in the interstellar medium: paving the way to the synthesis of adenine
We report the first detection in the interstellar medium of the Z-isomer of
cyanomethanimine (HNCHCN), an HCN dimer proposed as precursor of adenine. We
identified six transitions of Z-cyanomethanimine, along with five transitions
of E-cyanomethanimine, using IRAM 30m observations towards the Galactic Center
quiescent molecular cloud G+0.693. The Z-isomer has a column density of
(2.00.6)10 cm and an abundance of
1.510. The relative abundance ratio between the isomers is
[Z/E]6. This value cannot be explained by the two chemical formation
routes previously proposed (gas-phase and grain surface), which predicts
abundances ratios between 0.9 and 1.5. The observed [Z/E] ratio is in good
agreement with thermodynamic equilibrium at the gas kinetic temperature
(130210 K). Since isomerization is not possible in the ISM, the two species
may be formed at high temperature. New chemical models, including surface
chemistry on dust grains and gas-phase reactions, should be explored to explain
our findings. Whatever the formation mechanism, the high abundance of Z-HNCHCN
shows that precursors of adenine are efficiently formed in the ISM.Comment: Accepted in Monthly Notices of the Royal Astronomical Society Letter
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