91 research outputs found
Practical Approximation Algorithms for -Regularized Sparse Rank- Approximation to Higher-Order Tensors
Two approximation algorithms are proposed for -regularized sparse
rank-1 approximation to higher-order tensors. The algorithms are based on
multilinear relaxation and sparsification, which are easily implemented and
well scalable. In particular, the second one scales linearly with the size of
the input tensor. Based on a careful estimation of the -regularized
sparsification, theoretical approximation lower bounds are derived. Our
theoretical results also suggest an explicit way of choosing the regularization
parameters. Numerical examples are provided to verify the proposed algorithms
Approximation Algorithms for Sparse Best Rank-1 Approximation to Higher-Order Tensors
Sparse tensor best rank-1 approximation (BR1Approx), which is a sparsity
generalization of the dense tensor BR1Approx, and is a higher-order extension
of the sparse matrix BR1Approx, is one of the most important problems in sparse
tensor decomposition and related problems arising from statistics and machine
learning. By exploiting the multilinearity as well as the sparsity structure of
the problem, four approximation algorithms are proposed, which are easily
implemented, of low computational complexity, and can serve as initial
procedures for iterative algorithms. In addition, theoretically guaranteed
worst-case approximation lower bounds are proved for all the algorithms. We
provide numerical experiments on synthetic and real data to illustrate the
effectiveness of the proposed algorithms
A RUNX2 stabilization pathway mediates physiologic and pathologic bone formation
The osteoblast differentiation capacity of skeletal stem cells (SSCs) must be tightly regulated, as inadequate bone formation results in low bone mass and skeletal fragility, and over-exuberant osteogenesis results in heterotopic ossification (HO) of soft tissues. RUNX2 is essential for tuning this balance, but the mechanisms of posttranslational control of RUNX2 remain to be fully elucidated. Here, we identify that a CK2/HAUSP pathway is a key regulator of RUNX2 stability, as Casein kinase 2 (CK2) phosphorylates RUNX2, recruiting the deubiquitinase herpesvirus-associated ubiquitin-specific protease (HAUSP), which stabilizes RUNX2 by diverting it away from ubiquitin-dependent proteasomal degradation. This pathway is important for both the commitment of SSCs to osteoprogenitors and their subsequent maturation. This CK2/HAUSP/RUNX2 pathway is also necessary for HO, as its inhibition blocked HO in multiple models. Collectively, active deubiquitination of RUNX2 is required for bone formation and this CK2/HAUSP deubiquitination pathway offers therapeutic opportunities for disorders of inappropriate mineralization
Large and tunable magnetoresistance in van der Waals ferromagnet/semiconductor junctions
Magnetic tunnel junctions (MTJs) with conventional bulk ferromagnets separated by a nonmagnetic insulating layer are key building blocks in spintronics for magnetic sensors and memory. A radically different approach of using atomically-thin van der Waals (vdW) materials in MTJs is expected to boost their figure of merit, the tunneling magnetoresistance (TMR), while relaxing the lattice-matching requirements from the epitaxial growth and supporting high-quality integration of dissimilar materials with atomically-sharp interfaces. We report TMR up to 192% at 10 K in all-vdW Fe3GeTe2/GaSe/Fe3GeTe2 MTJs. Remarkably, instead of the usual insulating spacer, this large TMR is realized with a vdW semiconductor GaSe. Integration of semiconductors into the MTJs offers energy-band-tunability, bias dependence, magnetic proximity effects, and spin-dependent optical-selection rules. We demonstrate that not only the magnitude of the TMR is tuned by the semiconductor thickness but also the TMR sign can be reversed by varying the bias voltages, enabling modulation of highly spin-polarized carriers in vdW semiconductors
Large and tunable magnetoresistance in van der Waals Ferromagnet/Semiconductor junctions
Magnetic tunnel junctions (MTJs) with conventional bulk ferromagnets
separated by a nonmagnetic insulating layer are key building blocks in
spintronics for magnetic sensors and memory. A radically different approach of
using atomically-thin van der Waals (vdW) materials in MTJs is expected to
boost their figure of merit, the tunneling magnetoresistance (TMR), while
relaxing the lattice-matching requirements from the epitaxial growth and
supporting high-quality integration of dissimilar materials with
atomically-sharp interfaces. We report TMR up to 192% at 10 K in all-vdW
Fe3GeTe2/GaSe/Fe3GeTe2 MTJs. Remarkably, instead of the usual insulating
spacer, this large TMR is realized with a vdW semiconductor GaSe. Integration
of two-dimensional ferromagnets in semiconductor-based vdW junctions offers
gate-tunability, bias dependence, magnetic proximity effects, and
spin-dependent optical-selection rules. We demonstrate that not just the
magnitude, but also the TMR sign is tuned by the applied bias or the
semiconductor thickness, enabling modulation of highly spin-polarized carriers
in vdW semiconductors
セルロースナノファイバーを用いた高強度複合ゲルとその界面デザイン
京都大学0048新制・課程博士博士(農学)甲第22497号農博第2401号新制||農||1077(附属図書館)学位論文||R2||N5277(農学部図書室)京都大学大学院農学研究科森林科学専攻(主査)教授 矢野 浩之, 教授 和田 昌久, 教授 辻井 敬亘学位規則第4条第1項該当Doctor of Agricultural ScienceKyoto UniversityDFA
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